1457c8996SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 21da177e4SLinus Torvalds /* 3c54fce6eSTejun Heo * kernel/workqueue.c - generic async execution with shared worker pool 41da177e4SLinus Torvalds * 5c54fce6eSTejun Heo * Copyright (C) 2002 Ingo Molnar 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Derived from the taskqueue/keventd code by: 81da177e4SLinus Torvalds * David Woodhouse <dwmw2@infradead.org> 9e1f8e874SFrancois Cami * Andrew Morton 101da177e4SLinus Torvalds * Kai Petzke <wpp@marie.physik.tu-berlin.de> 111da177e4SLinus Torvalds * Theodore Ts'o <tytso@mit.edu> 1289ada679SChristoph Lameter * 13cde53535SChristoph Lameter * Made to use alloc_percpu by Christoph Lameter. 14c54fce6eSTejun Heo * 15c54fce6eSTejun Heo * Copyright (C) 2010 SUSE Linux Products GmbH 16c54fce6eSTejun Heo * Copyright (C) 2010 Tejun Heo <tj@kernel.org> 17c54fce6eSTejun Heo * 18c54fce6eSTejun Heo * This is the generic async execution mechanism. Work items as are 19c54fce6eSTejun Heo * executed in process context. The worker pool is shared and 20b11895c4SLibin * automatically managed. There are two worker pools for each CPU (one for 21b11895c4SLibin * normal work items and the other for high priority ones) and some extra 22b11895c4SLibin * pools for workqueues which are not bound to any specific CPU - the 23b11895c4SLibin * number of these backing pools is dynamic. 24c54fce6eSTejun Heo * 259a261491SBenjamin Peterson * Please read Documentation/core-api/workqueue.rst for details. 261da177e4SLinus Torvalds */ 271da177e4SLinus Torvalds 289984de1aSPaul Gortmaker #include <linux/export.h> 291da177e4SLinus Torvalds #include <linux/kernel.h> 301da177e4SLinus Torvalds #include <linux/sched.h> 311da177e4SLinus Torvalds #include <linux/init.h> 321da177e4SLinus Torvalds #include <linux/signal.h> 331da177e4SLinus Torvalds #include <linux/completion.h> 341da177e4SLinus Torvalds #include <linux/workqueue.h> 351da177e4SLinus Torvalds #include <linux/slab.h> 361da177e4SLinus Torvalds #include <linux/cpu.h> 371da177e4SLinus Torvalds #include <linux/notifier.h> 381da177e4SLinus Torvalds #include <linux/kthread.h> 391fa44ecaSJames Bottomley #include <linux/hardirq.h> 4046934023SChristoph Lameter #include <linux/mempolicy.h> 41341a5958SRafael J. Wysocki #include <linux/freezer.h> 42d5abe669SPeter Zijlstra #include <linux/debug_locks.h> 434e6045f1SJohannes Berg #include <linux/lockdep.h> 44c34056a3STejun Heo #include <linux/idr.h> 4529c91e99STejun Heo #include <linux/jhash.h> 4642f8570fSSasha Levin #include <linux/hashtable.h> 4776af4d93STejun Heo #include <linux/rculist.h> 48bce90380STejun Heo #include <linux/nodemask.h> 494c16bd32STejun Heo #include <linux/moduleparam.h> 503d1cb205STejun Heo #include <linux/uaccess.h> 51c98a9805STal Shorer #include <linux/sched/isolation.h> 52cd2440d6SPetr Mladek #include <linux/sched/debug.h> 5362635ea8SSergey Senozhatsky #include <linux/nmi.h> 54940d71c6SSergey Senozhatsky #include <linux/kvm_para.h> 55aa6fde93STejun Heo #include <linux/delay.h> 56e22bee78STejun Heo 57ea138446STejun Heo #include "workqueue_internal.h" 581da177e4SLinus Torvalds 59c8e55f36STejun Heo enum { 60bc2ae0f5STejun Heo /* 6124647570STejun Heo * worker_pool flags 62bc2ae0f5STejun Heo * 6324647570STejun Heo * A bound pool is either associated or disassociated with its CPU. 64bc2ae0f5STejun Heo * While associated (!DISASSOCIATED), all workers are bound to the 65bc2ae0f5STejun Heo * CPU and none has %WORKER_UNBOUND set and concurrency management 66bc2ae0f5STejun Heo * is in effect. 67bc2ae0f5STejun Heo * 68bc2ae0f5STejun Heo * While DISASSOCIATED, the cpu may be offline and all workers have 69bc2ae0f5STejun Heo * %WORKER_UNBOUND set and concurrency management disabled, and may 7024647570STejun Heo * be executing on any CPU. The pool behaves as an unbound one. 71bc2ae0f5STejun Heo * 72bc3a1afcSTejun Heo * Note that DISASSOCIATED should be flipped only while holding 731258fae7STejun Heo * wq_pool_attach_mutex to avoid changing binding state while 744736cbf7SLai Jiangshan * worker_attach_to_pool() is in progress. 75bc2ae0f5STejun Heo */ 76692b4825STejun Heo POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */ 7724647570STejun Heo POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 78db7bccf4STejun Heo 79c8e55f36STejun Heo /* worker flags */ 80c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 81c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 82e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 83fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 84f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 85a9ab775bSTejun Heo WORKER_REBOUND = 1 << 8, /* worker was rebound */ 86e22bee78STejun Heo 87a9ab775bSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | 88a9ab775bSTejun Heo WORKER_UNBOUND | WORKER_REBOUND, 89db7bccf4STejun Heo 90e34cdddbSTejun Heo NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ 914ce62e9eSTejun Heo 9229c91e99STejun Heo UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ 93c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 94db7bccf4STejun Heo 95e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 96e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 97e22bee78STejun Heo 983233cdbdSTejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, 993233cdbdSTejun Heo /* call for help after 10ms 1003233cdbdSTejun Heo (min two ticks) */ 101e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 102e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 1031da177e4SLinus Torvalds 1041da177e4SLinus Torvalds /* 105e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 1068698a745SDongsheng Yang * all cpus. Give MIN_NICE. 107e22bee78STejun Heo */ 1088698a745SDongsheng Yang RESCUER_NICE_LEVEL = MIN_NICE, 1098698a745SDongsheng Yang HIGHPRI_NICE_LEVEL = MIN_NICE, 110ecf6881fSTejun Heo 111ecf6881fSTejun Heo WQ_NAME_LEN = 24, 112c8e55f36STejun Heo }; 113c8e55f36STejun Heo 1141da177e4SLinus Torvalds /* 1154690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 1164690c4abSTejun Heo * 117e41e704bSTejun Heo * I: Modifiable by initialization/destruction paths and read-only for 118e41e704bSTejun Heo * everyone else. 1194690c4abSTejun Heo * 120e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 121e22bee78STejun Heo * only be modified and accessed from the local cpu. 122e22bee78STejun Heo * 123d565ed63STejun Heo * L: pool->lock protected. Access with pool->lock held. 1244690c4abSTejun Heo * 125bdf8b9bfSTejun Heo * K: Only modified by worker while holding pool->lock. Can be safely read by 126bdf8b9bfSTejun Heo * self, while holding pool->lock or from IRQ context if %current is the 127bdf8b9bfSTejun Heo * kworker. 128bdf8b9bfSTejun Heo * 129bdf8b9bfSTejun Heo * S: Only modified by worker self. 130bdf8b9bfSTejun Heo * 1311258fae7STejun Heo * A: wq_pool_attach_mutex protected. 132822d8405STejun Heo * 13368e13a67SLai Jiangshan * PL: wq_pool_mutex protected. 13476af4d93STejun Heo * 13524acfb71SThomas Gleixner * PR: wq_pool_mutex protected for writes. RCU protected for reads. 1365bcab335STejun Heo * 1375b95e1afSLai Jiangshan * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. 1385b95e1afSLai Jiangshan * 1395b95e1afSLai Jiangshan * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or 14024acfb71SThomas Gleixner * RCU for reads. 1415b95e1afSLai Jiangshan * 1423c25a55dSLai Jiangshan * WQ: wq->mutex protected. 1433c25a55dSLai Jiangshan * 14424acfb71SThomas Gleixner * WR: wq->mutex protected for writes. RCU protected for reads. 1452e109a28STejun Heo * 1462e109a28STejun Heo * MD: wq_mayday_lock protected. 147cd2440d6SPetr Mladek * 148cd2440d6SPetr Mladek * WD: Used internally by the watchdog. 1494690c4abSTejun Heo */ 1504690c4abSTejun Heo 1512eaebdb3STejun Heo /* struct worker is defined in workqueue_internal.h */ 152c34056a3STejun Heo 153bd7bdd43STejun Heo struct worker_pool { 154a9b8a985SSebastian Andrzej Siewior raw_spinlock_t lock; /* the pool lock */ 155d84ff051STejun Heo int cpu; /* I: the associated cpu */ 156f3f90ad4STejun Heo int node; /* I: the associated node ID */ 1579daf9e67STejun Heo int id; /* I: pool ID */ 158bc8b50c2STejun Heo unsigned int flags; /* L: flags */ 159bd7bdd43STejun Heo 16082607adcSTejun Heo unsigned long watchdog_ts; /* L: watchdog timestamp */ 161cd2440d6SPetr Mladek bool cpu_stall; /* WD: stalled cpu bound pool */ 16282607adcSTejun Heo 163bc35f7efSLai Jiangshan /* 164bc35f7efSLai Jiangshan * The counter is incremented in a process context on the associated CPU 165bc35f7efSLai Jiangshan * w/ preemption disabled, and decremented or reset in the same context 166bc35f7efSLai Jiangshan * but w/ pool->lock held. The readers grab pool->lock and are 167bc35f7efSLai Jiangshan * guaranteed to see if the counter reached zero. 168bc35f7efSLai Jiangshan */ 169bc35f7efSLai Jiangshan int nr_running; 17084f91c62SLai Jiangshan 171bd7bdd43STejun Heo struct list_head worklist; /* L: list of pending works */ 172ea1abd61SLai Jiangshan 1735826cc8fSLai Jiangshan int nr_workers; /* L: total number of workers */ 1745826cc8fSLai Jiangshan int nr_idle; /* L: currently idle workers */ 175bd7bdd43STejun Heo 1762c1f1a91SLai Jiangshan struct list_head idle_list; /* L: list of idle workers */ 177bd7bdd43STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 1783f959aa3SValentin Schneider struct work_struct idle_cull_work; /* L: worker idle cleanup */ 1793f959aa3SValentin Schneider 180bd7bdd43STejun Heo struct timer_list mayday_timer; /* L: SOS timer for workers */ 181bd7bdd43STejun Heo 182c5aa87bbSTejun Heo /* a workers is either on busy_hash or idle_list, or the manager */ 183c9e7cf27STejun Heo DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); 184c9e7cf27STejun Heo /* L: hash of busy workers */ 185c9e7cf27STejun Heo 1862607d7a6STejun Heo struct worker *manager; /* L: purely informational */ 18792f9c5c4SLai Jiangshan struct list_head workers; /* A: attached workers */ 188e02b9312SValentin Schneider struct list_head dying_workers; /* A: workers about to die */ 18960f5a4bcSLai Jiangshan struct completion *detach_completion; /* all workers detached */ 190e19e397aSTejun Heo 1917cda9aaeSLai Jiangshan struct ida worker_ida; /* worker IDs for task name */ 192e19e397aSTejun Heo 1937a4e344cSTejun Heo struct workqueue_attrs *attrs; /* I: worker attributes */ 19468e13a67SLai Jiangshan struct hlist_node hash_node; /* PL: unbound_pool_hash node */ 19568e13a67SLai Jiangshan int refcnt; /* PL: refcnt for unbound pools */ 1967a4e344cSTejun Heo 197e19e397aSTejun Heo /* 19824acfb71SThomas Gleixner * Destruction of pool is RCU protected to allow dereferences 19929c91e99STejun Heo * from get_work_pool(). 20029c91e99STejun Heo */ 20129c91e99STejun Heo struct rcu_head rcu; 20284f91c62SLai Jiangshan }; 2038b03ae3cSTejun Heo 2048b03ae3cSTejun Heo /* 205725e8ec5STejun Heo * Per-pool_workqueue statistics. These can be monitored using 206725e8ec5STejun Heo * tools/workqueue/wq_monitor.py. 207725e8ec5STejun Heo */ 208725e8ec5STejun Heo enum pool_workqueue_stats { 209725e8ec5STejun Heo PWQ_STAT_STARTED, /* work items started execution */ 210725e8ec5STejun Heo PWQ_STAT_COMPLETED, /* work items completed execution */ 2118a1dd1e5STejun Heo PWQ_STAT_CPU_TIME, /* total CPU time consumed */ 212616db877STejun Heo PWQ_STAT_CPU_INTENSIVE, /* wq_cpu_intensive_thresh_us violations */ 213725e8ec5STejun Heo PWQ_STAT_CM_WAKEUP, /* concurrency-management worker wakeups */ 2148639ecebSTejun Heo PWQ_STAT_REPATRIATED, /* unbound workers brought back into scope */ 215725e8ec5STejun Heo PWQ_STAT_MAYDAY, /* maydays to rescuer */ 216725e8ec5STejun Heo PWQ_STAT_RESCUED, /* linked work items executed by rescuer */ 217725e8ec5STejun Heo 218725e8ec5STejun Heo PWQ_NR_STATS, 219725e8ec5STejun Heo }; 220725e8ec5STejun Heo 221725e8ec5STejun Heo /* 222112202d9STejun Heo * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS 223112202d9STejun Heo * of work_struct->data are used for flags and the remaining high bits 224112202d9STejun Heo * point to the pwq; thus, pwqs need to be aligned at two's power of the 225112202d9STejun Heo * number of flag bits. 2261da177e4SLinus Torvalds */ 227112202d9STejun Heo struct pool_workqueue { 228bd7bdd43STejun Heo struct worker_pool *pool; /* I: the associated pool */ 2294690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 23073f53c4aSTejun Heo int work_color; /* L: current color */ 23173f53c4aSTejun Heo int flush_color; /* L: flushing color */ 2328864b4e5STejun Heo int refcnt; /* L: reference count */ 23373f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 23473f53c4aSTejun Heo /* L: nr of in_flight works */ 235018f3a13SLai Jiangshan 236018f3a13SLai Jiangshan /* 237018f3a13SLai Jiangshan * nr_active management and WORK_STRUCT_INACTIVE: 238018f3a13SLai Jiangshan * 239018f3a13SLai Jiangshan * When pwq->nr_active >= max_active, new work item is queued to 240018f3a13SLai Jiangshan * pwq->inactive_works instead of pool->worklist and marked with 241018f3a13SLai Jiangshan * WORK_STRUCT_INACTIVE. 242018f3a13SLai Jiangshan * 243018f3a13SLai Jiangshan * All work items marked with WORK_STRUCT_INACTIVE do not participate 244018f3a13SLai Jiangshan * in pwq->nr_active and all work items in pwq->inactive_works are 245018f3a13SLai Jiangshan * marked with WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE 246018f3a13SLai Jiangshan * work items are in pwq->inactive_works. Some of them are ready to 247018f3a13SLai Jiangshan * run in pool->worklist or worker->scheduled. Those work itmes are 248018f3a13SLai Jiangshan * only struct wq_barrier which is used for flush_work() and should 249018f3a13SLai Jiangshan * not participate in pwq->nr_active. For non-barrier work item, it 250018f3a13SLai Jiangshan * is marked with WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. 251018f3a13SLai Jiangshan */ 2521e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 253a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 254f97a4a1aSLai Jiangshan struct list_head inactive_works; /* L: inactive works */ 2553c25a55dSLai Jiangshan struct list_head pwqs_node; /* WR: node on wq->pwqs */ 2562e109a28STejun Heo struct list_head mayday_node; /* MD: node on wq->maydays */ 2578864b4e5STejun Heo 258725e8ec5STejun Heo u64 stats[PWQ_NR_STATS]; 259725e8ec5STejun Heo 2608864b4e5STejun Heo /* 261967b494eSTejun Heo * Release of unbound pwq is punted to a kthread_worker. See put_pwq() 262687a9aa5STejun Heo * and pwq_release_workfn() for details. pool_workqueue itself is also 263687a9aa5STejun Heo * RCU protected so that the first pwq can be determined without 264967b494eSTejun Heo * grabbing wq->mutex. 2658864b4e5STejun Heo */ 266687a9aa5STejun Heo struct kthread_work release_work; 2678864b4e5STejun Heo struct rcu_head rcu; 268e904e6c2STejun Heo } __aligned(1 << WORK_STRUCT_FLAG_BITS); 2691da177e4SLinus Torvalds 2701da177e4SLinus Torvalds /* 27173f53c4aSTejun Heo * Structure used to wait for workqueue flush. 27273f53c4aSTejun Heo */ 27373f53c4aSTejun Heo struct wq_flusher { 2743c25a55dSLai Jiangshan struct list_head list; /* WQ: list of flushers */ 2753c25a55dSLai Jiangshan int flush_color; /* WQ: flush color waiting for */ 27673f53c4aSTejun Heo struct completion done; /* flush completion */ 27773f53c4aSTejun Heo }; 2781da177e4SLinus Torvalds 279226223abSTejun Heo struct wq_device; 280226223abSTejun Heo 28173f53c4aSTejun Heo /* 282c5aa87bbSTejun Heo * The externally visible workqueue. It relays the issued work items to 283c5aa87bbSTejun Heo * the appropriate worker_pool through its pool_workqueues. 2841da177e4SLinus Torvalds */ 2851da177e4SLinus Torvalds struct workqueue_struct { 2863c25a55dSLai Jiangshan struct list_head pwqs; /* WR: all pwqs of this wq */ 287e2dca7adSTejun Heo struct list_head list; /* PR: list of all workqueues */ 28873f53c4aSTejun Heo 2893c25a55dSLai Jiangshan struct mutex mutex; /* protects this wq */ 2903c25a55dSLai Jiangshan int work_color; /* WQ: current work color */ 2913c25a55dSLai Jiangshan int flush_color; /* WQ: current flush color */ 292112202d9STejun Heo atomic_t nr_pwqs_to_flush; /* flush in progress */ 2933c25a55dSLai Jiangshan struct wq_flusher *first_flusher; /* WQ: first flusher */ 2943c25a55dSLai Jiangshan struct list_head flusher_queue; /* WQ: flush waiters */ 2953c25a55dSLai Jiangshan struct list_head flusher_overflow; /* WQ: flush overflow list */ 29673f53c4aSTejun Heo 2972e109a28STejun Heo struct list_head maydays; /* MD: pwqs requesting rescue */ 29830ae2fc0STejun Heo struct worker *rescuer; /* MD: rescue worker */ 299e22bee78STejun Heo 30087fc741eSLai Jiangshan int nr_drainers; /* WQ: drain in progress */ 301a357fc03SLai Jiangshan int saved_max_active; /* WQ: saved pwq max_active */ 302226223abSTejun Heo 3035b95e1afSLai Jiangshan struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ 3045b95e1afSLai Jiangshan struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */ 3056029a918STejun Heo 306226223abSTejun Heo #ifdef CONFIG_SYSFS 307226223abSTejun Heo struct wq_device *wq_dev; /* I: for sysfs interface */ 308226223abSTejun Heo #endif 3094e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 310669de8bdSBart Van Assche char *lock_name; 311669de8bdSBart Van Assche struct lock_class_key key; 3124e6045f1SJohannes Berg struct lockdep_map lockdep_map; 3134e6045f1SJohannes Berg #endif 314ecf6881fSTejun Heo char name[WQ_NAME_LEN]; /* I: workqueue name */ 3152728fd2fSTejun Heo 316e2dca7adSTejun Heo /* 31724acfb71SThomas Gleixner * Destruction of workqueue_struct is RCU protected to allow walking 31824acfb71SThomas Gleixner * the workqueues list without grabbing wq_pool_mutex. 319e2dca7adSTejun Heo * This is used to dump all workqueues from sysrq. 320e2dca7adSTejun Heo */ 321e2dca7adSTejun Heo struct rcu_head rcu; 322e2dca7adSTejun Heo 3232728fd2fSTejun Heo /* hot fields used during command issue, aligned to cacheline */ 3242728fd2fSTejun Heo unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ 325636b927eSTejun Heo struct pool_workqueue __percpu __rcu **cpu_pwq; /* I: per-cpu pwqs */ 3261da177e4SLinus Torvalds }; 3271da177e4SLinus Torvalds 328e904e6c2STejun Heo static struct kmem_cache *pwq_cache; 329e904e6c2STejun Heo 33084193c07STejun Heo /* 33184193c07STejun Heo * Each pod type describes how CPUs should be grouped for unbound workqueues. 33284193c07STejun Heo * See the comment above workqueue_attrs->affn_scope. 33384193c07STejun Heo */ 33484193c07STejun Heo struct wq_pod_type { 33584193c07STejun Heo int nr_pods; /* number of pods */ 33684193c07STejun Heo cpumask_var_t *pod_cpus; /* pod -> cpus */ 33784193c07STejun Heo int *pod_node; /* pod -> node */ 33884193c07STejun Heo int *cpu_pod; /* cpu -> pod */ 33984193c07STejun Heo }; 34084193c07STejun Heo 34184193c07STejun Heo static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES]; 342523a301eSTejun Heo static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE; 34363c5484eSTejun Heo 34463c5484eSTejun Heo static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = { 345523a301eSTejun Heo [WQ_AFFN_DFL] = "default", 34663c5484eSTejun Heo [WQ_AFFN_CPU] = "cpu", 34763c5484eSTejun Heo [WQ_AFFN_SMT] = "smt", 34863c5484eSTejun Heo [WQ_AFFN_CACHE] = "cache", 34963c5484eSTejun Heo [WQ_AFFN_NUMA] = "numa", 35063c5484eSTejun Heo [WQ_AFFN_SYSTEM] = "system", 35163c5484eSTejun Heo }; 352bce90380STejun Heo 353616db877STejun Heo /* 354616db877STejun Heo * Per-cpu work items which run for longer than the following threshold are 355616db877STejun Heo * automatically considered CPU intensive and excluded from concurrency 356616db877STejun Heo * management to prevent them from noticeably delaying other per-cpu work items. 357aa6fde93STejun Heo * ULONG_MAX indicates that the user hasn't overridden it with a boot parameter. 358aa6fde93STejun Heo * The actual value is initialized in wq_cpu_intensive_thresh_init(). 359616db877STejun Heo */ 360aa6fde93STejun Heo static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX; 361616db877STejun Heo module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644); 362616db877STejun Heo 363cee22a15SViresh Kumar /* see the comment above the definition of WQ_POWER_EFFICIENT */ 364552f530cSLuis R. Rodriguez static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); 365cee22a15SViresh Kumar module_param_named(power_efficient, wq_power_efficient, bool, 0444); 366cee22a15SViresh Kumar 367863b710bSTejun Heo static bool wq_online; /* can kworkers be created yet? */ 3683347fa09STejun Heo 369fef59c9cSTejun Heo /* buf for wq_update_unbound_pod_attrs(), protected by CPU hotplug exclusion */ 370fef59c9cSTejun Heo static struct workqueue_attrs *wq_update_pod_attrs_buf; 3714c16bd32STejun Heo 37268e13a67SLai Jiangshan static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ 3731258fae7STejun Heo static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ 374a9b8a985SSebastian Andrzej Siewior static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ 375d8bb65abSSebastian Andrzej Siewior /* wait for manager to go away */ 376d8bb65abSSebastian Andrzej Siewior static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait); 3775bcab335STejun Heo 378e2dca7adSTejun Heo static LIST_HEAD(workqueues); /* PR: list of all workqueues */ 37968e13a67SLai Jiangshan static bool workqueue_freezing; /* PL: have wqs started freezing? */ 3807d19c5ceSTejun Heo 38199c621efSLai Jiangshan /* PL&A: allowable cpus for unbound wqs and work items */ 382ef557180SMike Galbraith static cpumask_var_t wq_unbound_cpumask; 383ef557180SMike Galbraith 384ace3c549Stiozhang /* for further constrain wq_unbound_cpumask by cmdline parameter*/ 385ace3c549Stiozhang static struct cpumask wq_cmdline_cpumask __initdata; 386ace3c549Stiozhang 387ef557180SMike Galbraith /* CPU where unbound work was last round robin scheduled from this CPU */ 388ef557180SMike Galbraith static DEFINE_PER_CPU(int, wq_rr_cpu_last); 389b05a7928SFrederic Weisbecker 390f303fccbSTejun Heo /* 391f303fccbSTejun Heo * Local execution of unbound work items is no longer guaranteed. The 392f303fccbSTejun Heo * following always forces round-robin CPU selection on unbound work items 393f303fccbSTejun Heo * to uncover usages which depend on it. 394f303fccbSTejun Heo */ 395f303fccbSTejun Heo #ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU 396f303fccbSTejun Heo static bool wq_debug_force_rr_cpu = true; 397f303fccbSTejun Heo #else 398f303fccbSTejun Heo static bool wq_debug_force_rr_cpu = false; 399f303fccbSTejun Heo #endif 400f303fccbSTejun Heo module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); 401f303fccbSTejun Heo 4027d19c5ceSTejun Heo /* the per-cpu worker pools */ 40325528213SPeter Zijlstra static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); 4047d19c5ceSTejun Heo 40568e13a67SLai Jiangshan static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ 4067d19c5ceSTejun Heo 40768e13a67SLai Jiangshan /* PL: hash of all unbound pools keyed by pool->attrs */ 40829c91e99STejun Heo static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); 40929c91e99STejun Heo 410c5aa87bbSTejun Heo /* I: attributes used when instantiating standard unbound pools on demand */ 41129c91e99STejun Heo static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; 41229c91e99STejun Heo 4138a2b7538STejun Heo /* I: attributes used when instantiating ordered pools on demand */ 4148a2b7538STejun Heo static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; 4158a2b7538STejun Heo 416967b494eSTejun Heo /* 417967b494eSTejun Heo * I: kthread_worker to release pwq's. pwq release needs to be bounced to a 418967b494eSTejun Heo * process context while holding a pool lock. Bounce to a dedicated kthread 419967b494eSTejun Heo * worker to avoid A-A deadlocks. 420967b494eSTejun Heo */ 421967b494eSTejun Heo static struct kthread_worker *pwq_release_worker; 422967b494eSTejun Heo 423d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 424ad7b1f84SMarc Dionne EXPORT_SYMBOL(system_wq); 425044c782cSValentin Ilie struct workqueue_struct *system_highpri_wq __read_mostly; 4261aabe902SJoonsoo Kim EXPORT_SYMBOL_GPL(system_highpri_wq); 427044c782cSValentin Ilie struct workqueue_struct *system_long_wq __read_mostly; 428d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 429044c782cSValentin Ilie struct workqueue_struct *system_unbound_wq __read_mostly; 430f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 431044c782cSValentin Ilie struct workqueue_struct *system_freezable_wq __read_mostly; 43224d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 4330668106cSViresh Kumar struct workqueue_struct *system_power_efficient_wq __read_mostly; 4340668106cSViresh Kumar EXPORT_SYMBOL_GPL(system_power_efficient_wq); 4350668106cSViresh Kumar struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; 4360668106cSViresh Kumar EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); 437d320c038STejun Heo 4387d19c5ceSTejun Heo static int worker_thread(void *__worker); 4396ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq); 440c29eb853STejun Heo static void show_pwq(struct pool_workqueue *pwq); 44155df0933SImran Khan static void show_one_worker_pool(struct worker_pool *pool); 4427d19c5ceSTejun Heo 44397bd2347STejun Heo #define CREATE_TRACE_POINTS 44497bd2347STejun Heo #include <trace/events/workqueue.h> 44597bd2347STejun Heo 44668e13a67SLai Jiangshan #define assert_rcu_or_pool_mutex() \ 44724acfb71SThomas Gleixner RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ 448f78f5b90SPaul E. McKenney !lockdep_is_held(&wq_pool_mutex), \ 44924acfb71SThomas Gleixner "RCU or wq_pool_mutex should be held") 4505bcab335STejun Heo 4515b95e1afSLai Jiangshan #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \ 45224acfb71SThomas Gleixner RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ 453f78f5b90SPaul E. McKenney !lockdep_is_held(&wq->mutex) && \ 454f78f5b90SPaul E. McKenney !lockdep_is_held(&wq_pool_mutex), \ 45524acfb71SThomas Gleixner "RCU, wq->mutex or wq_pool_mutex should be held") 4565b95e1afSLai Jiangshan 457f02ae73aSTejun Heo #define for_each_cpu_worker_pool(pool, cpu) \ 458f02ae73aSTejun Heo for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ 459f02ae73aSTejun Heo (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ 4607a62c2c8STejun Heo (pool)++) 4614ce62e9eSTejun Heo 46249e3cf44STejun Heo /** 46317116969STejun Heo * for_each_pool - iterate through all worker_pools in the system 46417116969STejun Heo * @pool: iteration cursor 465611c92a0STejun Heo * @pi: integer used for iteration 466fa1b54e6STejun Heo * 46724acfb71SThomas Gleixner * This must be called either with wq_pool_mutex held or RCU read 46868e13a67SLai Jiangshan * locked. If the pool needs to be used beyond the locking in effect, the 46968e13a67SLai Jiangshan * caller is responsible for guaranteeing that the pool stays online. 470fa1b54e6STejun Heo * 471fa1b54e6STejun Heo * The if/else clause exists only for the lockdep assertion and can be 472fa1b54e6STejun Heo * ignored. 47317116969STejun Heo */ 474611c92a0STejun Heo #define for_each_pool(pool, pi) \ 475611c92a0STejun Heo idr_for_each_entry(&worker_pool_idr, pool, pi) \ 47668e13a67SLai Jiangshan if (({ assert_rcu_or_pool_mutex(); false; })) { } \ 477fa1b54e6STejun Heo else 47817116969STejun Heo 47917116969STejun Heo /** 480822d8405STejun Heo * for_each_pool_worker - iterate through all workers of a worker_pool 481822d8405STejun Heo * @worker: iteration cursor 482822d8405STejun Heo * @pool: worker_pool to iterate workers of 483822d8405STejun Heo * 4841258fae7STejun Heo * This must be called with wq_pool_attach_mutex. 485822d8405STejun Heo * 486822d8405STejun Heo * The if/else clause exists only for the lockdep assertion and can be 487822d8405STejun Heo * ignored. 488822d8405STejun Heo */ 489da028469SLai Jiangshan #define for_each_pool_worker(worker, pool) \ 490da028469SLai Jiangshan list_for_each_entry((worker), &(pool)->workers, node) \ 4911258fae7STejun Heo if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \ 492822d8405STejun Heo else 493822d8405STejun Heo 494822d8405STejun Heo /** 49549e3cf44STejun Heo * for_each_pwq - iterate through all pool_workqueues of the specified workqueue 49649e3cf44STejun Heo * @pwq: iteration cursor 49749e3cf44STejun Heo * @wq: the target workqueue 49876af4d93STejun Heo * 49924acfb71SThomas Gleixner * This must be called either with wq->mutex held or RCU read locked. 500794b18bcSTejun Heo * If the pwq needs to be used beyond the locking in effect, the caller is 501794b18bcSTejun Heo * responsible for guaranteeing that the pwq stays online. 50276af4d93STejun Heo * 50376af4d93STejun Heo * The if/else clause exists only for the lockdep assertion and can be 50476af4d93STejun Heo * ignored. 50549e3cf44STejun Heo */ 50649e3cf44STejun Heo #define for_each_pwq(pwq, wq) \ 50749e9d1a9SSebastian Andrzej Siewior list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \ 5085a644662SJoel Fernandes (Google) lockdep_is_held(&(wq->mutex))) 509f3421797STejun Heo 510dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 511dc186ad7SThomas Gleixner 512f9e62f31SStephen Boyd static const struct debug_obj_descr work_debug_descr; 513dc186ad7SThomas Gleixner 51499777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 51599777288SStanislaw Gruszka { 51699777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 51799777288SStanislaw Gruszka } 51899777288SStanislaw Gruszka 519b9fdac7fSDu, Changbin static bool work_is_static_object(void *addr) 520b9fdac7fSDu, Changbin { 521b9fdac7fSDu, Changbin struct work_struct *work = addr; 522b9fdac7fSDu, Changbin 523b9fdac7fSDu, Changbin return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work)); 524b9fdac7fSDu, Changbin } 525b9fdac7fSDu, Changbin 526dc186ad7SThomas Gleixner /* 527dc186ad7SThomas Gleixner * fixup_init is called when: 528dc186ad7SThomas Gleixner * - an active object is initialized 529dc186ad7SThomas Gleixner */ 53002a982a6SDu, Changbin static bool work_fixup_init(void *addr, enum debug_obj_state state) 531dc186ad7SThomas Gleixner { 532dc186ad7SThomas Gleixner struct work_struct *work = addr; 533dc186ad7SThomas Gleixner 534dc186ad7SThomas Gleixner switch (state) { 535dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 536dc186ad7SThomas Gleixner cancel_work_sync(work); 537dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 53802a982a6SDu, Changbin return true; 539dc186ad7SThomas Gleixner default: 54002a982a6SDu, Changbin return false; 541dc186ad7SThomas Gleixner } 542dc186ad7SThomas Gleixner } 543dc186ad7SThomas Gleixner 544dc186ad7SThomas Gleixner /* 545dc186ad7SThomas Gleixner * fixup_free is called when: 546dc186ad7SThomas Gleixner * - an active object is freed 547dc186ad7SThomas Gleixner */ 54802a982a6SDu, Changbin static bool work_fixup_free(void *addr, enum debug_obj_state state) 549dc186ad7SThomas Gleixner { 550dc186ad7SThomas Gleixner struct work_struct *work = addr; 551dc186ad7SThomas Gleixner 552dc186ad7SThomas Gleixner switch (state) { 553dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 554dc186ad7SThomas Gleixner cancel_work_sync(work); 555dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 55602a982a6SDu, Changbin return true; 557dc186ad7SThomas Gleixner default: 55802a982a6SDu, Changbin return false; 559dc186ad7SThomas Gleixner } 560dc186ad7SThomas Gleixner } 561dc186ad7SThomas Gleixner 562f9e62f31SStephen Boyd static const struct debug_obj_descr work_debug_descr = { 563dc186ad7SThomas Gleixner .name = "work_struct", 56499777288SStanislaw Gruszka .debug_hint = work_debug_hint, 565b9fdac7fSDu, Changbin .is_static_object = work_is_static_object, 566dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 567dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 568dc186ad7SThomas Gleixner }; 569dc186ad7SThomas Gleixner 570dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 571dc186ad7SThomas Gleixner { 572dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 573dc186ad7SThomas Gleixner } 574dc186ad7SThomas Gleixner 575dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 576dc186ad7SThomas Gleixner { 577dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 578dc186ad7SThomas Gleixner } 579dc186ad7SThomas Gleixner 580dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 581dc186ad7SThomas Gleixner { 582dc186ad7SThomas Gleixner if (onstack) 583dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 584dc186ad7SThomas Gleixner else 585dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 586dc186ad7SThomas Gleixner } 587dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 588dc186ad7SThomas Gleixner 589dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 590dc186ad7SThomas Gleixner { 591dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 592dc186ad7SThomas Gleixner } 593dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 594dc186ad7SThomas Gleixner 595ea2e64f2SThomas Gleixner void destroy_delayed_work_on_stack(struct delayed_work *work) 596ea2e64f2SThomas Gleixner { 597ea2e64f2SThomas Gleixner destroy_timer_on_stack(&work->timer); 598ea2e64f2SThomas Gleixner debug_object_free(&work->work, &work_debug_descr); 599ea2e64f2SThomas Gleixner } 600ea2e64f2SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); 601ea2e64f2SThomas Gleixner 602dc186ad7SThomas Gleixner #else 603dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 604dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 605dc186ad7SThomas Gleixner #endif 606dc186ad7SThomas Gleixner 6074e8b22bdSLi Bin /** 60867dc8325SCai Huoqing * worker_pool_assign_id - allocate ID and assign it to @pool 6094e8b22bdSLi Bin * @pool: the pool pointer of interest 6104e8b22bdSLi Bin * 6114e8b22bdSLi Bin * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned 6124e8b22bdSLi Bin * successfully, -errno on failure. 6134e8b22bdSLi Bin */ 6149daf9e67STejun Heo static int worker_pool_assign_id(struct worker_pool *pool) 6159daf9e67STejun Heo { 6169daf9e67STejun Heo int ret; 6179daf9e67STejun Heo 61868e13a67SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 6195bcab335STejun Heo 6204e8b22bdSLi Bin ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, 6214e8b22bdSLi Bin GFP_KERNEL); 622229641a6STejun Heo if (ret >= 0) { 623e68035fbSTejun Heo pool->id = ret; 624229641a6STejun Heo return 0; 625229641a6STejun Heo } 6269daf9e67STejun Heo return ret; 6279daf9e67STejun Heo } 6289daf9e67STejun Heo 62973f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 63073f53c4aSTejun Heo { 63173f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 63273f53c4aSTejun Heo } 63373f53c4aSTejun Heo 634c4560c2cSLai Jiangshan static int get_work_color(unsigned long work_data) 63573f53c4aSTejun Heo { 636c4560c2cSLai Jiangshan return (work_data >> WORK_STRUCT_COLOR_SHIFT) & 63773f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 63873f53c4aSTejun Heo } 63973f53c4aSTejun Heo 64073f53c4aSTejun Heo static int work_next_color(int color) 64173f53c4aSTejun Heo { 64273f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 643a848e3b6SOleg Nesterov } 644a848e3b6SOleg Nesterov 6454594bf15SDavid Howells /* 646112202d9STejun Heo * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data 647112202d9STejun Heo * contain the pointer to the queued pwq. Once execution starts, the flag 6487c3eed5cSTejun Heo * is cleared and the high bits contain OFFQ flags and pool ID. 6497a22ad75STejun Heo * 650112202d9STejun Heo * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() 651112202d9STejun Heo * and clear_work_data() can be used to set the pwq, pool or clear 652bbb68dfaSTejun Heo * work->data. These functions should only be called while the work is 653bbb68dfaSTejun Heo * owned - ie. while the PENDING bit is set. 6547a22ad75STejun Heo * 655112202d9STejun Heo * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq 6567c3eed5cSTejun Heo * corresponding to a work. Pool is available once the work has been 657112202d9STejun Heo * queued anywhere after initialization until it is sync canceled. pwq is 6587c3eed5cSTejun Heo * available only while the work item is queued. 659bbb68dfaSTejun Heo * 660bbb68dfaSTejun Heo * %WORK_OFFQ_CANCELING is used to mark a work item which is being 661bbb68dfaSTejun Heo * canceled. While being canceled, a work item may have its PENDING set 662bbb68dfaSTejun Heo * but stay off timer and worklist for arbitrarily long and nobody should 663bbb68dfaSTejun Heo * try to steal the PENDING bit. 6644594bf15SDavid Howells */ 6657a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 6667a22ad75STejun Heo unsigned long flags) 6677a22ad75STejun Heo { 6686183c009STejun Heo WARN_ON_ONCE(!work_pending(work)); 6697a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 6707a22ad75STejun Heo } 6717a22ad75STejun Heo 672112202d9STejun Heo static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, 6734690c4abSTejun Heo unsigned long extra_flags) 674365970a1SDavid Howells { 675112202d9STejun Heo set_work_data(work, (unsigned long)pwq, 676112202d9STejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); 677365970a1SDavid Howells } 678365970a1SDavid Howells 6794468a00fSLai Jiangshan static void set_work_pool_and_keep_pending(struct work_struct *work, 6804468a00fSLai Jiangshan int pool_id) 6814468a00fSLai Jiangshan { 6824468a00fSLai Jiangshan set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 6834468a00fSLai Jiangshan WORK_STRUCT_PENDING); 6844468a00fSLai Jiangshan } 6854468a00fSLai Jiangshan 6867c3eed5cSTejun Heo static void set_work_pool_and_clear_pending(struct work_struct *work, 6877c3eed5cSTejun Heo int pool_id) 6884d707b9fSOleg Nesterov { 68923657bb1STejun Heo /* 69023657bb1STejun Heo * The following wmb is paired with the implied mb in 69123657bb1STejun Heo * test_and_set_bit(PENDING) and ensures all updates to @work made 69223657bb1STejun Heo * here are visible to and precede any updates by the next PENDING 69323657bb1STejun Heo * owner. 69423657bb1STejun Heo */ 69523657bb1STejun Heo smp_wmb(); 6967c3eed5cSTejun Heo set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); 697346c09f8SRoman Pen /* 698346c09f8SRoman Pen * The following mb guarantees that previous clear of a PENDING bit 699346c09f8SRoman Pen * will not be reordered with any speculative LOADS or STORES from 700346c09f8SRoman Pen * work->current_func, which is executed afterwards. This possible 7018bdc6201SLiu Song * reordering can lead to a missed execution on attempt to queue 702346c09f8SRoman Pen * the same @work. E.g. consider this case: 703346c09f8SRoman Pen * 704346c09f8SRoman Pen * CPU#0 CPU#1 705346c09f8SRoman Pen * ---------------------------- -------------------------------- 706346c09f8SRoman Pen * 707346c09f8SRoman Pen * 1 STORE event_indicated 708346c09f8SRoman Pen * 2 queue_work_on() { 709346c09f8SRoman Pen * 3 test_and_set_bit(PENDING) 710346c09f8SRoman Pen * 4 } set_..._and_clear_pending() { 711346c09f8SRoman Pen * 5 set_work_data() # clear bit 712346c09f8SRoman Pen * 6 smp_mb() 713346c09f8SRoman Pen * 7 work->current_func() { 714346c09f8SRoman Pen * 8 LOAD event_indicated 715346c09f8SRoman Pen * } 716346c09f8SRoman Pen * 717346c09f8SRoman Pen * Without an explicit full barrier speculative LOAD on line 8 can 718346c09f8SRoman Pen * be executed before CPU#0 does STORE on line 1. If that happens, 719346c09f8SRoman Pen * CPU#0 observes the PENDING bit is still set and new execution of 720346c09f8SRoman Pen * a @work is not queued in a hope, that CPU#1 will eventually 721346c09f8SRoman Pen * finish the queued @work. Meanwhile CPU#1 does not see 722346c09f8SRoman Pen * event_indicated is set, because speculative LOAD was executed 723346c09f8SRoman Pen * before actual STORE. 724346c09f8SRoman Pen */ 725346c09f8SRoman Pen smp_mb(); 7264d707b9fSOleg Nesterov } 7274d707b9fSOleg Nesterov 7287a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 729365970a1SDavid Howells { 7307c3eed5cSTejun Heo smp_wmb(); /* see set_work_pool_and_clear_pending() */ 7317c3eed5cSTejun Heo set_work_data(work, WORK_STRUCT_NO_POOL, 0); 7327a22ad75STejun Heo } 7337a22ad75STejun Heo 734afa4bb77SLinus Torvalds static inline struct pool_workqueue *work_struct_pwq(unsigned long data) 735afa4bb77SLinus Torvalds { 736afa4bb77SLinus Torvalds return (struct pool_workqueue *)(data & WORK_STRUCT_WQ_DATA_MASK); 737afa4bb77SLinus Torvalds } 738afa4bb77SLinus Torvalds 739112202d9STejun Heo static struct pool_workqueue *get_work_pwq(struct work_struct *work) 7407a22ad75STejun Heo { 741e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 7427a22ad75STejun Heo 743112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 744afa4bb77SLinus Torvalds return work_struct_pwq(data); 745e120153dSTejun Heo else 746e120153dSTejun Heo return NULL; 7477a22ad75STejun Heo } 7487a22ad75STejun Heo 7497c3eed5cSTejun Heo /** 7507c3eed5cSTejun Heo * get_work_pool - return the worker_pool a given work was associated with 7517c3eed5cSTejun Heo * @work: the work item of interest 7527c3eed5cSTejun Heo * 75368e13a67SLai Jiangshan * Pools are created and destroyed under wq_pool_mutex, and allows read 75424acfb71SThomas Gleixner * access under RCU read lock. As such, this function should be 75524acfb71SThomas Gleixner * called under wq_pool_mutex or inside of a rcu_read_lock() region. 756fa1b54e6STejun Heo * 757fa1b54e6STejun Heo * All fields of the returned pool are accessible as long as the above 758fa1b54e6STejun Heo * mentioned locking is in effect. If the returned pool needs to be used 759fa1b54e6STejun Heo * beyond the critical section, the caller is responsible for ensuring the 760fa1b54e6STejun Heo * returned pool is and stays online. 761d185af30SYacine Belkadi * 762d185af30SYacine Belkadi * Return: The worker_pool @work was last associated with. %NULL if none. 7637c3eed5cSTejun Heo */ 7647c3eed5cSTejun Heo static struct worker_pool *get_work_pool(struct work_struct *work) 7657a22ad75STejun Heo { 766e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 7677c3eed5cSTejun Heo int pool_id; 7687a22ad75STejun Heo 76968e13a67SLai Jiangshan assert_rcu_or_pool_mutex(); 770fa1b54e6STejun Heo 771112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 772afa4bb77SLinus Torvalds return work_struct_pwq(data)->pool; 7737a22ad75STejun Heo 7747c3eed5cSTejun Heo pool_id = data >> WORK_OFFQ_POOL_SHIFT; 7757c3eed5cSTejun Heo if (pool_id == WORK_OFFQ_POOL_NONE) 7767a22ad75STejun Heo return NULL; 7777a22ad75STejun Heo 778fa1b54e6STejun Heo return idr_find(&worker_pool_idr, pool_id); 7797c3eed5cSTejun Heo } 7807c3eed5cSTejun Heo 7817c3eed5cSTejun Heo /** 7827c3eed5cSTejun Heo * get_work_pool_id - return the worker pool ID a given work is associated with 7837c3eed5cSTejun Heo * @work: the work item of interest 7847c3eed5cSTejun Heo * 785d185af30SYacine Belkadi * Return: The worker_pool ID @work was last associated with. 7867c3eed5cSTejun Heo * %WORK_OFFQ_POOL_NONE if none. 7877c3eed5cSTejun Heo */ 7887c3eed5cSTejun Heo static int get_work_pool_id(struct work_struct *work) 7897c3eed5cSTejun Heo { 79054d5b7d0SLai Jiangshan unsigned long data = atomic_long_read(&work->data); 7917c3eed5cSTejun Heo 792112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 793afa4bb77SLinus Torvalds return work_struct_pwq(data)->pool->id; 79454d5b7d0SLai Jiangshan 79554d5b7d0SLai Jiangshan return data >> WORK_OFFQ_POOL_SHIFT; 7967c3eed5cSTejun Heo } 7977c3eed5cSTejun Heo 798bbb68dfaSTejun Heo static void mark_work_canceling(struct work_struct *work) 799bbb68dfaSTejun Heo { 8007c3eed5cSTejun Heo unsigned long pool_id = get_work_pool_id(work); 801bbb68dfaSTejun Heo 8027c3eed5cSTejun Heo pool_id <<= WORK_OFFQ_POOL_SHIFT; 8037c3eed5cSTejun Heo set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); 804bbb68dfaSTejun Heo } 805bbb68dfaSTejun Heo 806bbb68dfaSTejun Heo static bool work_is_canceling(struct work_struct *work) 807bbb68dfaSTejun Heo { 808bbb68dfaSTejun Heo unsigned long data = atomic_long_read(&work->data); 809bbb68dfaSTejun Heo 810112202d9STejun Heo return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); 811bbb68dfaSTejun Heo } 812bbb68dfaSTejun Heo 813e22bee78STejun Heo /* 8143270476aSTejun Heo * Policy functions. These define the policies on how the global worker 8153270476aSTejun Heo * pools are managed. Unless noted otherwise, these functions assume that 816d565ed63STejun Heo * they're being called with pool->lock held. 817e22bee78STejun Heo */ 818e22bee78STejun Heo 819e22bee78STejun Heo /* 820e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 821e22bee78STejun Heo * running workers. 822974271c4STejun Heo * 823974271c4STejun Heo * Note that, because unbound workers never contribute to nr_running, this 824706026c2STejun Heo * function will always return %true for unbound pools as long as the 825974271c4STejun Heo * worklist isn't empty. 826e22bee78STejun Heo */ 82763d95a91STejun Heo static bool need_more_worker(struct worker_pool *pool) 828e22bee78STejun Heo { 8290219a352STejun Heo return !list_empty(&pool->worklist) && !pool->nr_running; 830e22bee78STejun Heo } 831e22bee78STejun Heo 832e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 83363d95a91STejun Heo static bool may_start_working(struct worker_pool *pool) 834e22bee78STejun Heo { 83563d95a91STejun Heo return pool->nr_idle; 836e22bee78STejun Heo } 837e22bee78STejun Heo 838e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 83963d95a91STejun Heo static bool keep_working(struct worker_pool *pool) 840e22bee78STejun Heo { 841bc35f7efSLai Jiangshan return !list_empty(&pool->worklist) && (pool->nr_running <= 1); 842e22bee78STejun Heo } 843e22bee78STejun Heo 844e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 84563d95a91STejun Heo static bool need_to_create_worker(struct worker_pool *pool) 846e22bee78STejun Heo { 84763d95a91STejun Heo return need_more_worker(pool) && !may_start_working(pool); 848e22bee78STejun Heo } 849e22bee78STejun Heo 850e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 85163d95a91STejun Heo static bool too_many_workers(struct worker_pool *pool) 852e22bee78STejun Heo { 853692b4825STejun Heo bool managing = pool->flags & POOL_MANAGER_ACTIVE; 85463d95a91STejun Heo int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 85563d95a91STejun Heo int nr_busy = pool->nr_workers - nr_idle; 856e22bee78STejun Heo 857e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 858e22bee78STejun Heo } 859e22bee78STejun Heo 8604690c4abSTejun Heo /** 861e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 862cb444766STejun Heo * @worker: self 863d302f017STejun Heo * @flags: flags to set 864d302f017STejun Heo * 865228f1d00SLai Jiangshan * Set @flags in @worker->flags and adjust nr_running accordingly. 866d302f017STejun Heo */ 867228f1d00SLai Jiangshan static inline void worker_set_flags(struct worker *worker, unsigned int flags) 868d302f017STejun Heo { 869bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 870e22bee78STejun Heo 871bc8b50c2STejun Heo lockdep_assert_held(&pool->lock); 872cb444766STejun Heo 873228f1d00SLai Jiangshan /* If transitioning into NOT_RUNNING, adjust nr_running. */ 874e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 875e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 876bc35f7efSLai Jiangshan pool->nr_running--; 877e22bee78STejun Heo } 878e22bee78STejun Heo 879d302f017STejun Heo worker->flags |= flags; 880d302f017STejun Heo } 881d302f017STejun Heo 882d302f017STejun Heo /** 883e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 884cb444766STejun Heo * @worker: self 885d302f017STejun Heo * @flags: flags to clear 886d302f017STejun Heo * 887e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 888d302f017STejun Heo */ 889d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 890d302f017STejun Heo { 89163d95a91STejun Heo struct worker_pool *pool = worker->pool; 892e22bee78STejun Heo unsigned int oflags = worker->flags; 893e22bee78STejun Heo 894bc8b50c2STejun Heo lockdep_assert_held(&pool->lock); 895cb444766STejun Heo 896d302f017STejun Heo worker->flags &= ~flags; 897e22bee78STejun Heo 89842c025f3STejun Heo /* 89942c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 90042c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 90142c025f3STejun Heo * of multiple flags, not a single flag. 90242c025f3STejun Heo */ 903e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 904e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 905bc35f7efSLai Jiangshan pool->nr_running++; 906d302f017STejun Heo } 907d302f017STejun Heo 908797e8345STejun Heo /* Return the first idle worker. Called with pool->lock held. */ 909797e8345STejun Heo static struct worker *first_idle_worker(struct worker_pool *pool) 910797e8345STejun Heo { 911797e8345STejun Heo if (unlikely(list_empty(&pool->idle_list))) 912797e8345STejun Heo return NULL; 913797e8345STejun Heo 914797e8345STejun Heo return list_first_entry(&pool->idle_list, struct worker, entry); 915797e8345STejun Heo } 916797e8345STejun Heo 917797e8345STejun Heo /** 918797e8345STejun Heo * worker_enter_idle - enter idle state 919797e8345STejun Heo * @worker: worker which is entering idle state 920797e8345STejun Heo * 921797e8345STejun Heo * @worker is entering idle state. Update stats and idle timer if 922797e8345STejun Heo * necessary. 923797e8345STejun Heo * 924797e8345STejun Heo * LOCKING: 925797e8345STejun Heo * raw_spin_lock_irq(pool->lock). 926797e8345STejun Heo */ 927797e8345STejun Heo static void worker_enter_idle(struct worker *worker) 928797e8345STejun Heo { 929797e8345STejun Heo struct worker_pool *pool = worker->pool; 930797e8345STejun Heo 931797e8345STejun Heo if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || 932797e8345STejun Heo WARN_ON_ONCE(!list_empty(&worker->entry) && 933797e8345STejun Heo (worker->hentry.next || worker->hentry.pprev))) 934797e8345STejun Heo return; 935797e8345STejun Heo 936797e8345STejun Heo /* can't use worker_set_flags(), also called from create_worker() */ 937797e8345STejun Heo worker->flags |= WORKER_IDLE; 938797e8345STejun Heo pool->nr_idle++; 939797e8345STejun Heo worker->last_active = jiffies; 940797e8345STejun Heo 941797e8345STejun Heo /* idle_list is LIFO */ 942797e8345STejun Heo list_add(&worker->entry, &pool->idle_list); 943797e8345STejun Heo 944797e8345STejun Heo if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 945797e8345STejun Heo mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 946797e8345STejun Heo 947797e8345STejun Heo /* Sanity check nr_running. */ 948797e8345STejun Heo WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running); 949797e8345STejun Heo } 950797e8345STejun Heo 951797e8345STejun Heo /** 952797e8345STejun Heo * worker_leave_idle - leave idle state 953797e8345STejun Heo * @worker: worker which is leaving idle state 954797e8345STejun Heo * 955797e8345STejun Heo * @worker is leaving idle state. Update stats. 956797e8345STejun Heo * 957797e8345STejun Heo * LOCKING: 958797e8345STejun Heo * raw_spin_lock_irq(pool->lock). 959797e8345STejun Heo */ 960797e8345STejun Heo static void worker_leave_idle(struct worker *worker) 961797e8345STejun Heo { 962797e8345STejun Heo struct worker_pool *pool = worker->pool; 963797e8345STejun Heo 964797e8345STejun Heo if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) 965797e8345STejun Heo return; 966797e8345STejun Heo worker_clr_flags(worker, WORKER_IDLE); 967797e8345STejun Heo pool->nr_idle--; 968797e8345STejun Heo list_del_init(&worker->entry); 969797e8345STejun Heo } 970797e8345STejun Heo 971797e8345STejun Heo /** 972797e8345STejun Heo * find_worker_executing_work - find worker which is executing a work 973797e8345STejun Heo * @pool: pool of interest 974797e8345STejun Heo * @work: work to find worker for 975797e8345STejun Heo * 976797e8345STejun Heo * Find a worker which is executing @work on @pool by searching 977797e8345STejun Heo * @pool->busy_hash which is keyed by the address of @work. For a worker 978797e8345STejun Heo * to match, its current execution should match the address of @work and 979797e8345STejun Heo * its work function. This is to avoid unwanted dependency between 980797e8345STejun Heo * unrelated work executions through a work item being recycled while still 981797e8345STejun Heo * being executed. 982797e8345STejun Heo * 983797e8345STejun Heo * This is a bit tricky. A work item may be freed once its execution 984797e8345STejun Heo * starts and nothing prevents the freed area from being recycled for 985797e8345STejun Heo * another work item. If the same work item address ends up being reused 986797e8345STejun Heo * before the original execution finishes, workqueue will identify the 987797e8345STejun Heo * recycled work item as currently executing and make it wait until the 988797e8345STejun Heo * current execution finishes, introducing an unwanted dependency. 989797e8345STejun Heo * 990797e8345STejun Heo * This function checks the work item address and work function to avoid 991797e8345STejun Heo * false positives. Note that this isn't complete as one may construct a 992797e8345STejun Heo * work function which can introduce dependency onto itself through a 993797e8345STejun Heo * recycled work item. Well, if somebody wants to shoot oneself in the 994797e8345STejun Heo * foot that badly, there's only so much we can do, and if such deadlock 995797e8345STejun Heo * actually occurs, it should be easy to locate the culprit work function. 996797e8345STejun Heo * 997797e8345STejun Heo * CONTEXT: 998797e8345STejun Heo * raw_spin_lock_irq(pool->lock). 999797e8345STejun Heo * 1000797e8345STejun Heo * Return: 1001797e8345STejun Heo * Pointer to worker which is executing @work if found, %NULL 1002797e8345STejun Heo * otherwise. 1003797e8345STejun Heo */ 1004797e8345STejun Heo static struct worker *find_worker_executing_work(struct worker_pool *pool, 1005797e8345STejun Heo struct work_struct *work) 1006797e8345STejun Heo { 1007797e8345STejun Heo struct worker *worker; 1008797e8345STejun Heo 1009797e8345STejun Heo hash_for_each_possible(pool->busy_hash, worker, hentry, 1010797e8345STejun Heo (unsigned long)work) 1011797e8345STejun Heo if (worker->current_work == work && 1012797e8345STejun Heo worker->current_func == work->func) 1013797e8345STejun Heo return worker; 1014797e8345STejun Heo 1015797e8345STejun Heo return NULL; 1016797e8345STejun Heo } 1017797e8345STejun Heo 1018797e8345STejun Heo /** 1019797e8345STejun Heo * move_linked_works - move linked works to a list 1020797e8345STejun Heo * @work: start of series of works to be scheduled 1021797e8345STejun Heo * @head: target list to append @work to 1022797e8345STejun Heo * @nextp: out parameter for nested worklist walking 1023797e8345STejun Heo * 1024873eaca6STejun Heo * Schedule linked works starting from @work to @head. Work series to be 1025873eaca6STejun Heo * scheduled starts at @work and includes any consecutive work with 1026873eaca6STejun Heo * WORK_STRUCT_LINKED set in its predecessor. See assign_work() for details on 1027873eaca6STejun Heo * @nextp. 1028797e8345STejun Heo * 1029797e8345STejun Heo * CONTEXT: 1030797e8345STejun Heo * raw_spin_lock_irq(pool->lock). 1031797e8345STejun Heo */ 1032797e8345STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1033797e8345STejun Heo struct work_struct **nextp) 1034797e8345STejun Heo { 1035797e8345STejun Heo struct work_struct *n; 1036797e8345STejun Heo 1037797e8345STejun Heo /* 1038797e8345STejun Heo * Linked worklist will always end before the end of the list, 1039797e8345STejun Heo * use NULL for list head. 1040797e8345STejun Heo */ 1041797e8345STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1042797e8345STejun Heo list_move_tail(&work->entry, head); 1043797e8345STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1044797e8345STejun Heo break; 1045797e8345STejun Heo } 1046797e8345STejun Heo 1047797e8345STejun Heo /* 1048797e8345STejun Heo * If we're already inside safe list traversal and have moved 1049797e8345STejun Heo * multiple works to the scheduled queue, the next position 1050797e8345STejun Heo * needs to be updated. 1051797e8345STejun Heo */ 1052797e8345STejun Heo if (nextp) 1053797e8345STejun Heo *nextp = n; 1054797e8345STejun Heo } 1055797e8345STejun Heo 1056797e8345STejun Heo /** 1057873eaca6STejun Heo * assign_work - assign a work item and its linked work items to a worker 1058873eaca6STejun Heo * @work: work to assign 1059873eaca6STejun Heo * @worker: worker to assign to 1060873eaca6STejun Heo * @nextp: out parameter for nested worklist walking 1061873eaca6STejun Heo * 1062873eaca6STejun Heo * Assign @work and its linked work items to @worker. If @work is already being 1063873eaca6STejun Heo * executed by another worker in the same pool, it'll be punted there. 1064873eaca6STejun Heo * 1065873eaca6STejun Heo * If @nextp is not NULL, it's updated to point to the next work of the last 1066873eaca6STejun Heo * scheduled work. This allows assign_work() to be nested inside 1067873eaca6STejun Heo * list_for_each_entry_safe(). 1068873eaca6STejun Heo * 1069873eaca6STejun Heo * Returns %true if @work was successfully assigned to @worker. %false if @work 1070873eaca6STejun Heo * was punted to another worker already executing it. 1071873eaca6STejun Heo */ 1072873eaca6STejun Heo static bool assign_work(struct work_struct *work, struct worker *worker, 1073873eaca6STejun Heo struct work_struct **nextp) 1074873eaca6STejun Heo { 1075873eaca6STejun Heo struct worker_pool *pool = worker->pool; 1076873eaca6STejun Heo struct worker *collision; 1077873eaca6STejun Heo 1078873eaca6STejun Heo lockdep_assert_held(&pool->lock); 1079873eaca6STejun Heo 1080873eaca6STejun Heo /* 1081873eaca6STejun Heo * A single work shouldn't be executed concurrently by multiple workers. 1082873eaca6STejun Heo * __queue_work() ensures that @work doesn't jump to a different pool 1083873eaca6STejun Heo * while still running in the previous pool. Here, we should ensure that 1084873eaca6STejun Heo * @work is not executed concurrently by multiple workers from the same 1085873eaca6STejun Heo * pool. Check whether anyone is already processing the work. If so, 1086873eaca6STejun Heo * defer the work to the currently executing one. 1087873eaca6STejun Heo */ 1088873eaca6STejun Heo collision = find_worker_executing_work(pool, work); 1089873eaca6STejun Heo if (unlikely(collision)) { 1090873eaca6STejun Heo move_linked_works(work, &collision->scheduled, nextp); 1091873eaca6STejun Heo return false; 1092873eaca6STejun Heo } 1093873eaca6STejun Heo 1094873eaca6STejun Heo move_linked_works(work, &worker->scheduled, nextp); 1095873eaca6STejun Heo return true; 1096873eaca6STejun Heo } 1097873eaca6STejun Heo 1098873eaca6STejun Heo /** 10990219a352STejun Heo * kick_pool - wake up an idle worker if necessary 11000219a352STejun Heo * @pool: pool to kick 1101797e8345STejun Heo * 11020219a352STejun Heo * @pool may have pending work items. Wake up worker if necessary. Returns 11030219a352STejun Heo * whether a worker was woken up. 1104797e8345STejun Heo */ 11050219a352STejun Heo static bool kick_pool(struct worker_pool *pool) 1106797e8345STejun Heo { 1107797e8345STejun Heo struct worker *worker = first_idle_worker(pool); 11088639ecebSTejun Heo struct task_struct *p; 1109797e8345STejun Heo 11100219a352STejun Heo lockdep_assert_held(&pool->lock); 11110219a352STejun Heo 11120219a352STejun Heo if (!need_more_worker(pool) || !worker) 11130219a352STejun Heo return false; 11140219a352STejun Heo 11158639ecebSTejun Heo p = worker->task; 11168639ecebSTejun Heo 11178639ecebSTejun Heo #ifdef CONFIG_SMP 11188639ecebSTejun Heo /* 11198639ecebSTejun Heo * Idle @worker is about to execute @work and waking up provides an 11208639ecebSTejun Heo * opportunity to migrate @worker at a lower cost by setting the task's 11218639ecebSTejun Heo * wake_cpu field. Let's see if we want to move @worker to improve 11228639ecebSTejun Heo * execution locality. 11238639ecebSTejun Heo * 11248639ecebSTejun Heo * We're waking the worker that went idle the latest and there's some 11258639ecebSTejun Heo * chance that @worker is marked idle but hasn't gone off CPU yet. If 11268639ecebSTejun Heo * so, setting the wake_cpu won't do anything. As this is a best-effort 11278639ecebSTejun Heo * optimization and the race window is narrow, let's leave as-is for 11288639ecebSTejun Heo * now. If this becomes pronounced, we can skip over workers which are 11298639ecebSTejun Heo * still on cpu when picking an idle worker. 11308639ecebSTejun Heo * 11318639ecebSTejun Heo * If @pool has non-strict affinity, @worker might have ended up outside 11328639ecebSTejun Heo * its affinity scope. Repatriate. 11338639ecebSTejun Heo */ 11348639ecebSTejun Heo if (!pool->attrs->affn_strict && 11358639ecebSTejun Heo !cpumask_test_cpu(p->wake_cpu, pool->attrs->__pod_cpumask)) { 11368639ecebSTejun Heo struct work_struct *work = list_first_entry(&pool->worklist, 11378639ecebSTejun Heo struct work_struct, entry); 11388639ecebSTejun Heo p->wake_cpu = cpumask_any_distribute(pool->attrs->__pod_cpumask); 11398639ecebSTejun Heo get_work_pwq(work)->stats[PWQ_STAT_REPATRIATED]++; 11408639ecebSTejun Heo } 11418639ecebSTejun Heo #endif 11428639ecebSTejun Heo wake_up_process(p); 11430219a352STejun Heo return true; 1144797e8345STejun Heo } 1145797e8345STejun Heo 114663638450STejun Heo #ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT 114763638450STejun Heo 114863638450STejun Heo /* 114963638450STejun Heo * Concurrency-managed per-cpu work items that hog CPU for longer than 115063638450STejun Heo * wq_cpu_intensive_thresh_us trigger the automatic CPU_INTENSIVE mechanism, 115163638450STejun Heo * which prevents them from stalling other concurrency-managed work items. If a 115263638450STejun Heo * work function keeps triggering this mechanism, it's likely that the work item 115363638450STejun Heo * should be using an unbound workqueue instead. 115463638450STejun Heo * 115563638450STejun Heo * wq_cpu_intensive_report() tracks work functions which trigger such conditions 115663638450STejun Heo * and report them so that they can be examined and converted to use unbound 115763638450STejun Heo * workqueues as appropriate. To avoid flooding the console, each violating work 115863638450STejun Heo * function is tracked and reported with exponential backoff. 115963638450STejun Heo */ 116063638450STejun Heo #define WCI_MAX_ENTS 128 116163638450STejun Heo 116263638450STejun Heo struct wci_ent { 116363638450STejun Heo work_func_t func; 116463638450STejun Heo atomic64_t cnt; 116563638450STejun Heo struct hlist_node hash_node; 116663638450STejun Heo }; 116763638450STejun Heo 116863638450STejun Heo static struct wci_ent wci_ents[WCI_MAX_ENTS]; 116963638450STejun Heo static int wci_nr_ents; 117063638450STejun Heo static DEFINE_RAW_SPINLOCK(wci_lock); 117163638450STejun Heo static DEFINE_HASHTABLE(wci_hash, ilog2(WCI_MAX_ENTS)); 117263638450STejun Heo 117363638450STejun Heo static struct wci_ent *wci_find_ent(work_func_t func) 117463638450STejun Heo { 117563638450STejun Heo struct wci_ent *ent; 117663638450STejun Heo 117763638450STejun Heo hash_for_each_possible_rcu(wci_hash, ent, hash_node, 117863638450STejun Heo (unsigned long)func) { 117963638450STejun Heo if (ent->func == func) 118063638450STejun Heo return ent; 118163638450STejun Heo } 118263638450STejun Heo return NULL; 118363638450STejun Heo } 118463638450STejun Heo 118563638450STejun Heo static void wq_cpu_intensive_report(work_func_t func) 118663638450STejun Heo { 118763638450STejun Heo struct wci_ent *ent; 118863638450STejun Heo 118963638450STejun Heo restart: 119063638450STejun Heo ent = wci_find_ent(func); 119163638450STejun Heo if (ent) { 119263638450STejun Heo u64 cnt; 119363638450STejun Heo 119463638450STejun Heo /* 119563638450STejun Heo * Start reporting from the fourth time and back off 119663638450STejun Heo * exponentially. 119763638450STejun Heo */ 119863638450STejun Heo cnt = atomic64_inc_return_relaxed(&ent->cnt); 119963638450STejun Heo if (cnt >= 4 && is_power_of_2(cnt)) 120063638450STejun Heo printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching to WQ_UNBOUND\n", 120163638450STejun Heo ent->func, wq_cpu_intensive_thresh_us, 120263638450STejun Heo atomic64_read(&ent->cnt)); 120363638450STejun Heo return; 120463638450STejun Heo } 120563638450STejun Heo 120663638450STejun Heo /* 120763638450STejun Heo * @func is a new violation. Allocate a new entry for it. If wcn_ents[] 120863638450STejun Heo * is exhausted, something went really wrong and we probably made enough 120963638450STejun Heo * noise already. 121063638450STejun Heo */ 121163638450STejun Heo if (wci_nr_ents >= WCI_MAX_ENTS) 121263638450STejun Heo return; 121363638450STejun Heo 121463638450STejun Heo raw_spin_lock(&wci_lock); 121563638450STejun Heo 121663638450STejun Heo if (wci_nr_ents >= WCI_MAX_ENTS) { 121763638450STejun Heo raw_spin_unlock(&wci_lock); 121863638450STejun Heo return; 121963638450STejun Heo } 122063638450STejun Heo 122163638450STejun Heo if (wci_find_ent(func)) { 122263638450STejun Heo raw_spin_unlock(&wci_lock); 122363638450STejun Heo goto restart; 122463638450STejun Heo } 122563638450STejun Heo 122663638450STejun Heo ent = &wci_ents[wci_nr_ents++]; 122763638450STejun Heo ent->func = func; 122863638450STejun Heo atomic64_set(&ent->cnt, 1); 122963638450STejun Heo hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func); 123063638450STejun Heo 123163638450STejun Heo raw_spin_unlock(&wci_lock); 123263638450STejun Heo } 123363638450STejun Heo 123463638450STejun Heo #else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ 123563638450STejun Heo static void wq_cpu_intensive_report(work_func_t func) {} 123663638450STejun Heo #endif /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ 123763638450STejun Heo 1238c54d5046STejun Heo /** 12391da177e4SLinus Torvalds * wq_worker_running - a worker is running again 12401da177e4SLinus Torvalds * @task: task waking up 12411da177e4SLinus Torvalds * 12421da177e4SLinus Torvalds * This function is called when a worker returns from schedule() 12431da177e4SLinus Torvalds */ 12441da177e4SLinus Torvalds void wq_worker_running(struct task_struct *task) 12451da177e4SLinus Torvalds { 12461da177e4SLinus Torvalds struct worker *worker = kthread_data(task); 12471da177e4SLinus Torvalds 1248c8f6219bSZqiang if (!READ_ONCE(worker->sleeping)) 12491da177e4SLinus Torvalds return; 12501da177e4SLinus Torvalds 12511da177e4SLinus Torvalds /* 12521da177e4SLinus Torvalds * If preempted by unbind_workers() between the WORKER_NOT_RUNNING check 12531da177e4SLinus Torvalds * and the nr_running increment below, we may ruin the nr_running reset 12541da177e4SLinus Torvalds * and leave with an unexpected pool->nr_running == 1 on the newly unbound 12551da177e4SLinus Torvalds * pool. Protect against such race. 12561da177e4SLinus Torvalds */ 12571da177e4SLinus Torvalds preempt_disable(); 12581da177e4SLinus Torvalds if (!(worker->flags & WORKER_NOT_RUNNING)) 12591da177e4SLinus Torvalds worker->pool->nr_running++; 12601da177e4SLinus Torvalds preempt_enable(); 1261616db877STejun Heo 1262616db877STejun Heo /* 1263616db877STejun Heo * CPU intensive auto-detection cares about how long a work item hogged 1264616db877STejun Heo * CPU without sleeping. Reset the starting timestamp on wakeup. 1265616db877STejun Heo */ 1266616db877STejun Heo worker->current_at = worker->task->se.sum_exec_runtime; 1267616db877STejun Heo 1268c8f6219bSZqiang WRITE_ONCE(worker->sleeping, 0); 12691da177e4SLinus Torvalds } 12701da177e4SLinus Torvalds 12711da177e4SLinus Torvalds /** 12721da177e4SLinus Torvalds * wq_worker_sleeping - a worker is going to sleep 12731da177e4SLinus Torvalds * @task: task going to sleep 12741da177e4SLinus Torvalds * 12751da177e4SLinus Torvalds * This function is called from schedule() when a busy worker is 12761da177e4SLinus Torvalds * going to sleep. 12771da177e4SLinus Torvalds */ 12781da177e4SLinus Torvalds void wq_worker_sleeping(struct task_struct *task) 12791da177e4SLinus Torvalds { 12801da177e4SLinus Torvalds struct worker *worker = kthread_data(task); 12811da177e4SLinus Torvalds struct worker_pool *pool; 12821da177e4SLinus Torvalds 12831da177e4SLinus Torvalds /* 12841da177e4SLinus Torvalds * Rescuers, which may not have all the fields set up like normal 12851da177e4SLinus Torvalds * workers, also reach here, let's not access anything before 12861da177e4SLinus Torvalds * checking NOT_RUNNING. 12871da177e4SLinus Torvalds */ 12881da177e4SLinus Torvalds if (worker->flags & WORKER_NOT_RUNNING) 12891da177e4SLinus Torvalds return; 12901da177e4SLinus Torvalds 12911da177e4SLinus Torvalds pool = worker->pool; 12921da177e4SLinus Torvalds 12931da177e4SLinus Torvalds /* Return if preempted before wq_worker_running() was reached */ 1294c8f6219bSZqiang if (READ_ONCE(worker->sleeping)) 12951da177e4SLinus Torvalds return; 12961da177e4SLinus Torvalds 1297c8f6219bSZqiang WRITE_ONCE(worker->sleeping, 1); 12981da177e4SLinus Torvalds raw_spin_lock_irq(&pool->lock); 12991da177e4SLinus Torvalds 13001da177e4SLinus Torvalds /* 13011da177e4SLinus Torvalds * Recheck in case unbind_workers() preempted us. We don't 13021da177e4SLinus Torvalds * want to decrement nr_running after the worker is unbound 13031da177e4SLinus Torvalds * and nr_running has been reset. 13041da177e4SLinus Torvalds */ 13051da177e4SLinus Torvalds if (worker->flags & WORKER_NOT_RUNNING) { 13061da177e4SLinus Torvalds raw_spin_unlock_irq(&pool->lock); 13071da177e4SLinus Torvalds return; 13081da177e4SLinus Torvalds } 13091da177e4SLinus Torvalds 13101da177e4SLinus Torvalds pool->nr_running--; 13110219a352STejun Heo if (kick_pool(pool)) 1312725e8ec5STejun Heo worker->current_pwq->stats[PWQ_STAT_CM_WAKEUP]++; 13130219a352STejun Heo 13141da177e4SLinus Torvalds raw_spin_unlock_irq(&pool->lock); 13151da177e4SLinus Torvalds } 13161da177e4SLinus Torvalds 13171da177e4SLinus Torvalds /** 1318616db877STejun Heo * wq_worker_tick - a scheduler tick occurred while a kworker is running 1319616db877STejun Heo * @task: task currently running 1320616db877STejun Heo * 1321616db877STejun Heo * Called from scheduler_tick(). We're in the IRQ context and the current 1322616db877STejun Heo * worker's fields which follow the 'K' locking rule can be accessed safely. 1323616db877STejun Heo */ 1324616db877STejun Heo void wq_worker_tick(struct task_struct *task) 1325616db877STejun Heo { 1326616db877STejun Heo struct worker *worker = kthread_data(task); 1327616db877STejun Heo struct pool_workqueue *pwq = worker->current_pwq; 1328616db877STejun Heo struct worker_pool *pool = worker->pool; 1329616db877STejun Heo 1330616db877STejun Heo if (!pwq) 1331616db877STejun Heo return; 1332616db877STejun Heo 13338a1dd1e5STejun Heo pwq->stats[PWQ_STAT_CPU_TIME] += TICK_USEC; 13348a1dd1e5STejun Heo 133518c8ae81SZqiang if (!wq_cpu_intensive_thresh_us) 133618c8ae81SZqiang return; 133718c8ae81SZqiang 1338616db877STejun Heo /* 1339616db877STejun Heo * If the current worker is concurrency managed and hogged the CPU for 1340616db877STejun Heo * longer than wq_cpu_intensive_thresh_us, it's automatically marked 1341616db877STejun Heo * CPU_INTENSIVE to avoid stalling other concurrency-managed work items. 1342c8f6219bSZqiang * 1343c8f6219bSZqiang * Set @worker->sleeping means that @worker is in the process of 1344c8f6219bSZqiang * switching out voluntarily and won't be contributing to 1345c8f6219bSZqiang * @pool->nr_running until it wakes up. As wq_worker_sleeping() also 1346c8f6219bSZqiang * decrements ->nr_running, setting CPU_INTENSIVE here can lead to 1347c8f6219bSZqiang * double decrements. The task is releasing the CPU anyway. Let's skip. 1348c8f6219bSZqiang * We probably want to make this prettier in the future. 1349616db877STejun Heo */ 1350c8f6219bSZqiang if ((worker->flags & WORKER_NOT_RUNNING) || READ_ONCE(worker->sleeping) || 1351616db877STejun Heo worker->task->se.sum_exec_runtime - worker->current_at < 1352616db877STejun Heo wq_cpu_intensive_thresh_us * NSEC_PER_USEC) 1353616db877STejun Heo return; 1354616db877STejun Heo 1355616db877STejun Heo raw_spin_lock(&pool->lock); 1356616db877STejun Heo 1357616db877STejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE); 135863638450STejun Heo wq_cpu_intensive_report(worker->current_func); 1359616db877STejun Heo pwq->stats[PWQ_STAT_CPU_INTENSIVE]++; 1360616db877STejun Heo 13610219a352STejun Heo if (kick_pool(pool)) 1362616db877STejun Heo pwq->stats[PWQ_STAT_CM_WAKEUP]++; 1363616db877STejun Heo 1364616db877STejun Heo raw_spin_unlock(&pool->lock); 1365616db877STejun Heo } 1366616db877STejun Heo 1367616db877STejun Heo /** 13681da177e4SLinus Torvalds * wq_worker_last_func - retrieve worker's last work function 13691da177e4SLinus Torvalds * @task: Task to retrieve last work function of. 13701da177e4SLinus Torvalds * 13711da177e4SLinus Torvalds * Determine the last function a worker executed. This is called from 13721da177e4SLinus Torvalds * the scheduler to get a worker's last known identity. 13731da177e4SLinus Torvalds * 13741da177e4SLinus Torvalds * CONTEXT: 13759b41ea72SAndrew Morton * raw_spin_lock_irq(rq->lock) 13761da177e4SLinus Torvalds * 13771da177e4SLinus Torvalds * This function is called during schedule() when a kworker is going 1378f756d5e2SNathan Lynch * to sleep. It's used by psi to identify aggregation workers during 1379f756d5e2SNathan Lynch * dequeuing, to allow periodic aggregation to shut-off when that 13801da177e4SLinus Torvalds * worker is the last task in the system or cgroup to go to sleep. 13811da177e4SLinus Torvalds * 13821da177e4SLinus Torvalds * As this function doesn't involve any workqueue-related locking, it 13831da177e4SLinus Torvalds * only returns stable values when called from inside the scheduler's 13841da177e4SLinus Torvalds * queuing and dequeuing paths, when @task, which must be a kworker, 13851da177e4SLinus Torvalds * is guaranteed to not be processing any works. 1386365970a1SDavid Howells * 1387365970a1SDavid Howells * Return: 1388365970a1SDavid Howells * The last work function %current executed as a worker, NULL if it 1389365970a1SDavid Howells * hasn't executed any work yet. 1390365970a1SDavid Howells */ 1391365970a1SDavid Howells work_func_t wq_worker_last_func(struct task_struct *task) 1392365970a1SDavid Howells { 1393365970a1SDavid Howells struct worker *worker = kthread_data(task); 1394365970a1SDavid Howells 1395365970a1SDavid Howells return worker->last_func; 1396365970a1SDavid Howells } 1397365970a1SDavid Howells 1398d302f017STejun Heo /** 13998864b4e5STejun Heo * get_pwq - get an extra reference on the specified pool_workqueue 14008864b4e5STejun Heo * @pwq: pool_workqueue to get 14018864b4e5STejun Heo * 14028864b4e5STejun Heo * Obtain an extra reference on @pwq. The caller should guarantee that 14038864b4e5STejun Heo * @pwq has positive refcnt and be holding the matching pool->lock. 14048864b4e5STejun Heo */ 14058864b4e5STejun Heo static void get_pwq(struct pool_workqueue *pwq) 14068864b4e5STejun Heo { 14078864b4e5STejun Heo lockdep_assert_held(&pwq->pool->lock); 14088864b4e5STejun Heo WARN_ON_ONCE(pwq->refcnt <= 0); 14098864b4e5STejun Heo pwq->refcnt++; 14108864b4e5STejun Heo } 14118864b4e5STejun Heo 14128864b4e5STejun Heo /** 14138864b4e5STejun Heo * put_pwq - put a pool_workqueue reference 14148864b4e5STejun Heo * @pwq: pool_workqueue to put 14158864b4e5STejun Heo * 14168864b4e5STejun Heo * Drop a reference of @pwq. If its refcnt reaches zero, schedule its 14178864b4e5STejun Heo * destruction. The caller should be holding the matching pool->lock. 14188864b4e5STejun Heo */ 14198864b4e5STejun Heo static void put_pwq(struct pool_workqueue *pwq) 14208864b4e5STejun Heo { 14218864b4e5STejun Heo lockdep_assert_held(&pwq->pool->lock); 14228864b4e5STejun Heo if (likely(--pwq->refcnt)) 14238864b4e5STejun Heo return; 14248864b4e5STejun Heo /* 1425967b494eSTejun Heo * @pwq can't be released under pool->lock, bounce to a dedicated 1426967b494eSTejun Heo * kthread_worker to avoid A-A deadlocks. 14278864b4e5STejun Heo */ 1428687a9aa5STejun Heo kthread_queue_work(pwq_release_worker, &pwq->release_work); 14298864b4e5STejun Heo } 14308864b4e5STejun Heo 1431dce90d47STejun Heo /** 1432dce90d47STejun Heo * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock 1433dce90d47STejun Heo * @pwq: pool_workqueue to put (can be %NULL) 1434dce90d47STejun Heo * 1435dce90d47STejun Heo * put_pwq() with locking. This function also allows %NULL @pwq. 1436dce90d47STejun Heo */ 1437dce90d47STejun Heo static void put_pwq_unlocked(struct pool_workqueue *pwq) 1438dce90d47STejun Heo { 1439dce90d47STejun Heo if (pwq) { 1440dce90d47STejun Heo /* 144124acfb71SThomas Gleixner * As both pwqs and pools are RCU protected, the 1442dce90d47STejun Heo * following lock operations are safe. 1443dce90d47STejun Heo */ 1444a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pwq->pool->lock); 1445dce90d47STejun Heo put_pwq(pwq); 1446a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pwq->pool->lock); 1447dce90d47STejun Heo } 1448dce90d47STejun Heo } 1449dce90d47STejun Heo 1450f97a4a1aSLai Jiangshan static void pwq_activate_inactive_work(struct work_struct *work) 1451bf4ede01STejun Heo { 1452112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 1453bf4ede01STejun Heo 1454bf4ede01STejun Heo trace_workqueue_activate_work(work); 145582607adcSTejun Heo if (list_empty(&pwq->pool->worklist)) 145682607adcSTejun Heo pwq->pool->watchdog_ts = jiffies; 1457112202d9STejun Heo move_linked_works(work, &pwq->pool->worklist, NULL); 1458f97a4a1aSLai Jiangshan __clear_bit(WORK_STRUCT_INACTIVE_BIT, work_data_bits(work)); 1459112202d9STejun Heo pwq->nr_active++; 1460bf4ede01STejun Heo } 1461bf4ede01STejun Heo 1462f97a4a1aSLai Jiangshan static void pwq_activate_first_inactive(struct pool_workqueue *pwq) 14633aa62497SLai Jiangshan { 1464f97a4a1aSLai Jiangshan struct work_struct *work = list_first_entry(&pwq->inactive_works, 14653aa62497SLai Jiangshan struct work_struct, entry); 14663aa62497SLai Jiangshan 1467f97a4a1aSLai Jiangshan pwq_activate_inactive_work(work); 14683aa62497SLai Jiangshan } 14693aa62497SLai Jiangshan 1470bf4ede01STejun Heo /** 1471112202d9STejun Heo * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight 1472112202d9STejun Heo * @pwq: pwq of interest 1473c4560c2cSLai Jiangshan * @work_data: work_data of work which left the queue 1474bf4ede01STejun Heo * 1475bf4ede01STejun Heo * A work either has completed or is removed from pending queue, 1476112202d9STejun Heo * decrement nr_in_flight of its pwq and handle workqueue flushing. 1477bf4ede01STejun Heo * 1478bf4ede01STejun Heo * CONTEXT: 1479a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 1480bf4ede01STejun Heo */ 1481c4560c2cSLai Jiangshan static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data) 1482bf4ede01STejun Heo { 1483c4560c2cSLai Jiangshan int color = get_work_color(work_data); 1484c4560c2cSLai Jiangshan 1485018f3a13SLai Jiangshan if (!(work_data & WORK_STRUCT_INACTIVE)) { 1486112202d9STejun Heo pwq->nr_active--; 1487f97a4a1aSLai Jiangshan if (!list_empty(&pwq->inactive_works)) { 1488f97a4a1aSLai Jiangshan /* one down, submit an inactive one */ 1489112202d9STejun Heo if (pwq->nr_active < pwq->max_active) 1490f97a4a1aSLai Jiangshan pwq_activate_first_inactive(pwq); 1491bf4ede01STejun Heo } 1492018f3a13SLai Jiangshan } 1493018f3a13SLai Jiangshan 1494018f3a13SLai Jiangshan pwq->nr_in_flight[color]--; 1495bf4ede01STejun Heo 1496bf4ede01STejun Heo /* is flush in progress and are we at the flushing tip? */ 1497112202d9STejun Heo if (likely(pwq->flush_color != color)) 14988864b4e5STejun Heo goto out_put; 1499bf4ede01STejun Heo 1500bf4ede01STejun Heo /* are there still in-flight works? */ 1501112202d9STejun Heo if (pwq->nr_in_flight[color]) 15028864b4e5STejun Heo goto out_put; 1503bf4ede01STejun Heo 1504112202d9STejun Heo /* this pwq is done, clear flush_color */ 1505112202d9STejun Heo pwq->flush_color = -1; 1506bf4ede01STejun Heo 1507bf4ede01STejun Heo /* 1508112202d9STejun Heo * If this was the last pwq, wake up the first flusher. It 1509bf4ede01STejun Heo * will handle the rest. 1510bf4ede01STejun Heo */ 1511112202d9STejun Heo if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) 1512112202d9STejun Heo complete(&pwq->wq->first_flusher->done); 15138864b4e5STejun Heo out_put: 15148864b4e5STejun Heo put_pwq(pwq); 1515bf4ede01STejun Heo } 1516bf4ede01STejun Heo 151736e227d2STejun Heo /** 1518bbb68dfaSTejun Heo * try_to_grab_pending - steal work item from worklist and disable irq 151936e227d2STejun Heo * @work: work item to steal 152036e227d2STejun Heo * @is_dwork: @work is a delayed_work 1521bbb68dfaSTejun Heo * @flags: place to store irq state 152236e227d2STejun Heo * 152336e227d2STejun Heo * Try to grab PENDING bit of @work. This function can handle @work in any 1524d185af30SYacine Belkadi * stable state - idle, on timer or on worklist. 152536e227d2STejun Heo * 1526d185af30SYacine Belkadi * Return: 15273eb6b31bSMauro Carvalho Chehab * 15283eb6b31bSMauro Carvalho Chehab * ======== ================================================================ 152936e227d2STejun Heo * 1 if @work was pending and we successfully stole PENDING 153036e227d2STejun Heo * 0 if @work was idle and we claimed PENDING 153136e227d2STejun Heo * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 1532bbb68dfaSTejun Heo * -ENOENT if someone else is canceling @work, this state may persist 1533bbb68dfaSTejun Heo * for arbitrarily long 15343eb6b31bSMauro Carvalho Chehab * ======== ================================================================ 153536e227d2STejun Heo * 1536d185af30SYacine Belkadi * Note: 1537bbb68dfaSTejun Heo * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 1538e0aecdd8STejun Heo * interrupted while holding PENDING and @work off queue, irq must be 1539e0aecdd8STejun Heo * disabled on entry. This, combined with delayed_work->timer being 1540e0aecdd8STejun Heo * irqsafe, ensures that we return -EAGAIN for finite short period of time. 1541bbb68dfaSTejun Heo * 1542bbb68dfaSTejun Heo * On successful return, >= 0, irq is disabled and the caller is 1543bbb68dfaSTejun Heo * responsible for releasing it using local_irq_restore(*@flags). 1544bbb68dfaSTejun Heo * 1545e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 1546bf4ede01STejun Heo */ 1547bbb68dfaSTejun Heo static int try_to_grab_pending(struct work_struct *work, bool is_dwork, 1548bbb68dfaSTejun Heo unsigned long *flags) 1549bf4ede01STejun Heo { 1550d565ed63STejun Heo struct worker_pool *pool; 1551112202d9STejun Heo struct pool_workqueue *pwq; 1552bf4ede01STejun Heo 1553bbb68dfaSTejun Heo local_irq_save(*flags); 1554bbb68dfaSTejun Heo 155536e227d2STejun Heo /* try to steal the timer if it exists */ 155636e227d2STejun Heo if (is_dwork) { 155736e227d2STejun Heo struct delayed_work *dwork = to_delayed_work(work); 155836e227d2STejun Heo 1559e0aecdd8STejun Heo /* 1560e0aecdd8STejun Heo * dwork->timer is irqsafe. If del_timer() fails, it's 1561e0aecdd8STejun Heo * guaranteed that the timer is not queued anywhere and not 1562e0aecdd8STejun Heo * running on the local CPU. 1563e0aecdd8STejun Heo */ 156436e227d2STejun Heo if (likely(del_timer(&dwork->timer))) 156536e227d2STejun Heo return 1; 156636e227d2STejun Heo } 156736e227d2STejun Heo 156836e227d2STejun Heo /* try to claim PENDING the normal way */ 1569bf4ede01STejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 1570bf4ede01STejun Heo return 0; 1571bf4ede01STejun Heo 157224acfb71SThomas Gleixner rcu_read_lock(); 1573bf4ede01STejun Heo /* 1574bf4ede01STejun Heo * The queueing is in progress, or it is already queued. Try to 1575bf4ede01STejun Heo * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 1576bf4ede01STejun Heo */ 1577d565ed63STejun Heo pool = get_work_pool(work); 1578d565ed63STejun Heo if (!pool) 1579bbb68dfaSTejun Heo goto fail; 1580bf4ede01STejun Heo 1581a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&pool->lock); 1582bf4ede01STejun Heo /* 1583112202d9STejun Heo * work->data is guaranteed to point to pwq only while the work 1584112202d9STejun Heo * item is queued on pwq->wq, and both updating work->data to point 1585112202d9STejun Heo * to pwq on queueing and to pool on dequeueing are done under 1586112202d9STejun Heo * pwq->pool->lock. This in turn guarantees that, if work->data 1587112202d9STejun Heo * points to pwq which is associated with a locked pool, the work 15880b3dae68SLai Jiangshan * item is currently queued on that pool. 1589bf4ede01STejun Heo */ 1590112202d9STejun Heo pwq = get_work_pwq(work); 1591112202d9STejun Heo if (pwq && pwq->pool == pool) { 1592bf4ede01STejun Heo debug_work_deactivate(work); 15933aa62497SLai Jiangshan 15943aa62497SLai Jiangshan /* 1595018f3a13SLai Jiangshan * A cancelable inactive work item must be in the 1596018f3a13SLai Jiangshan * pwq->inactive_works since a queued barrier can't be 1597018f3a13SLai Jiangshan * canceled (see the comments in insert_wq_barrier()). 1598018f3a13SLai Jiangshan * 1599f97a4a1aSLai Jiangshan * An inactive work item cannot be grabbed directly because 1600d812796eSLai Jiangshan * it might have linked barrier work items which, if left 1601f97a4a1aSLai Jiangshan * on the inactive_works list, will confuse pwq->nr_active 160216062836STejun Heo * management later on and cause stall. Make sure the work 160316062836STejun Heo * item is activated before grabbing. 16043aa62497SLai Jiangshan */ 1605f97a4a1aSLai Jiangshan if (*work_data_bits(work) & WORK_STRUCT_INACTIVE) 1606f97a4a1aSLai Jiangshan pwq_activate_inactive_work(work); 16073aa62497SLai Jiangshan 1608bf4ede01STejun Heo list_del_init(&work->entry); 1609c4560c2cSLai Jiangshan pwq_dec_nr_in_flight(pwq, *work_data_bits(work)); 161036e227d2STejun Heo 1611112202d9STejun Heo /* work->data points to pwq iff queued, point to pool */ 16124468a00fSLai Jiangshan set_work_pool_and_keep_pending(work, pool->id); 16134468a00fSLai Jiangshan 1614a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&pool->lock); 161524acfb71SThomas Gleixner rcu_read_unlock(); 161636e227d2STejun Heo return 1; 1617bf4ede01STejun Heo } 1618a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&pool->lock); 1619bbb68dfaSTejun Heo fail: 162024acfb71SThomas Gleixner rcu_read_unlock(); 1621bbb68dfaSTejun Heo local_irq_restore(*flags); 1622bbb68dfaSTejun Heo if (work_is_canceling(work)) 1623bbb68dfaSTejun Heo return -ENOENT; 1624bbb68dfaSTejun Heo cpu_relax(); 162536e227d2STejun Heo return -EAGAIN; 1626bf4ede01STejun Heo } 1627bf4ede01STejun Heo 1628bf4ede01STejun Heo /** 1629706026c2STejun Heo * insert_work - insert a work into a pool 1630112202d9STejun Heo * @pwq: pwq @work belongs to 16314690c4abSTejun Heo * @work: work to insert 16324690c4abSTejun Heo * @head: insertion point 16334690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 16344690c4abSTejun Heo * 1635112202d9STejun Heo * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to 1636706026c2STejun Heo * work_struct flags. 16374690c4abSTejun Heo * 16384690c4abSTejun Heo * CONTEXT: 1639a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 1640365970a1SDavid Howells */ 1641112202d9STejun Heo static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, 1642112202d9STejun Heo struct list_head *head, unsigned int extra_flags) 1643b89deed3SOleg Nesterov { 1644fe089f87STejun Heo debug_work_activate(work); 1645e1d8aa9fSFrederic Weisbecker 1646e89a85d6SWalter Wu /* record the work call stack in order to print it in KASAN reports */ 1647f70da745SMarco Elver kasan_record_aux_stack_noalloc(work); 1648e89a85d6SWalter Wu 16494690c4abSTejun Heo /* we own @work, set data and link */ 1650112202d9STejun Heo set_work_pwq(work, pwq, extra_flags); 16511a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 16528864b4e5STejun Heo get_pwq(pwq); 1653b89deed3SOleg Nesterov } 1654b89deed3SOleg Nesterov 1655c8efcc25STejun Heo /* 1656c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 16578d03ecfeSTejun Heo * same workqueue. 1658c8efcc25STejun Heo */ 1659c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 1660c8efcc25STejun Heo { 1661c8efcc25STejun Heo struct worker *worker; 1662c8efcc25STejun Heo 16638d03ecfeSTejun Heo worker = current_wq_worker(); 1664c8efcc25STejun Heo /* 1665bf393fd4SBart Van Assche * Return %true iff I'm a worker executing a work item on @wq. If 16668d03ecfeSTejun Heo * I'm @worker, it's safe to dereference it without locking. 1667c8efcc25STejun Heo */ 1668112202d9STejun Heo return worker && worker->current_pwq->wq == wq; 1669c8efcc25STejun Heo } 1670c8efcc25STejun Heo 1671ef557180SMike Galbraith /* 1672ef557180SMike Galbraith * When queueing an unbound work item to a wq, prefer local CPU if allowed 1673ef557180SMike Galbraith * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to 1674ef557180SMike Galbraith * avoid perturbing sensitive tasks. 1675ef557180SMike Galbraith */ 1676ef557180SMike Galbraith static int wq_select_unbound_cpu(int cpu) 1677ef557180SMike Galbraith { 1678ef557180SMike Galbraith int new_cpu; 1679ef557180SMike Galbraith 1680f303fccbSTejun Heo if (likely(!wq_debug_force_rr_cpu)) { 1681ef557180SMike Galbraith if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) 1682ef557180SMike Galbraith return cpu; 1683a8ec5880SAmmar Faizi } else { 1684a8ec5880SAmmar Faizi pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n"); 1685f303fccbSTejun Heo } 1686f303fccbSTejun Heo 1687ef557180SMike Galbraith new_cpu = __this_cpu_read(wq_rr_cpu_last); 1688ef557180SMike Galbraith new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask); 1689ef557180SMike Galbraith if (unlikely(new_cpu >= nr_cpu_ids)) { 1690ef557180SMike Galbraith new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask); 1691ef557180SMike Galbraith if (unlikely(new_cpu >= nr_cpu_ids)) 1692ef557180SMike Galbraith return cpu; 1693ef557180SMike Galbraith } 1694ef557180SMike Galbraith __this_cpu_write(wq_rr_cpu_last, new_cpu); 1695ef557180SMike Galbraith 1696ef557180SMike Galbraith return new_cpu; 1697ef557180SMike Galbraith } 1698ef557180SMike Galbraith 1699d84ff051STejun Heo static void __queue_work(int cpu, struct workqueue_struct *wq, 17001da177e4SLinus Torvalds struct work_struct *work) 17011da177e4SLinus Torvalds { 1702112202d9STejun Heo struct pool_workqueue *pwq; 1703fe089f87STejun Heo struct worker_pool *last_pool, *pool; 17048a2e8e5dSTejun Heo unsigned int work_flags; 1705b75cac93SJoonsoo Kim unsigned int req_cpu = cpu; 17068930cabaSTejun Heo 17078930cabaSTejun Heo /* 17088930cabaSTejun Heo * While a work item is PENDING && off queue, a task trying to 17098930cabaSTejun Heo * steal the PENDING will busy-loop waiting for it to either get 17108930cabaSTejun Heo * queued or lose PENDING. Grabbing PENDING and queueing should 17118930cabaSTejun Heo * happen with IRQ disabled. 17128930cabaSTejun Heo */ 17138e8eb730SFrederic Weisbecker lockdep_assert_irqs_disabled(); 17141da177e4SLinus Torvalds 17151e19ffc6STejun Heo 171633e3f0a3SRichard Clark /* 171733e3f0a3SRichard Clark * For a draining wq, only works from the same workqueue are 171833e3f0a3SRichard Clark * allowed. The __WQ_DESTROYING helps to spot the issue that 171933e3f0a3SRichard Clark * queues a new work item to a wq after destroy_workqueue(wq). 172033e3f0a3SRichard Clark */ 172133e3f0a3SRichard Clark if (unlikely(wq->flags & (__WQ_DESTROYING | __WQ_DRAINING) && 172233e3f0a3SRichard Clark WARN_ON_ONCE(!is_chained_work(wq)))) 1723e41e704bSTejun Heo return; 172424acfb71SThomas Gleixner rcu_read_lock(); 17259e8cd2f5STejun Heo retry: 1726aa202f1fSHillf Danton /* pwq which will be used unless @work is executing elsewhere */ 1727636b927eSTejun Heo if (req_cpu == WORK_CPU_UNBOUND) { 1728636b927eSTejun Heo if (wq->flags & WQ_UNBOUND) 1729ef557180SMike Galbraith cpu = wq_select_unbound_cpu(raw_smp_processor_id()); 1730636b927eSTejun Heo else 1731aa202f1fSHillf Danton cpu = raw_smp_processor_id(); 1732aa202f1fSHillf Danton } 1733f3421797STejun Heo 1734636b927eSTejun Heo pwq = rcu_dereference(*per_cpu_ptr(wq->cpu_pwq, cpu)); 1735fe089f87STejun Heo pool = pwq->pool; 1736fe089f87STejun Heo 173718aa9effSTejun Heo /* 1738c9178087STejun Heo * If @work was previously on a different pool, it might still be 1739c9178087STejun Heo * running there, in which case the work needs to be queued on that 1740c9178087STejun Heo * pool to guarantee non-reentrancy. 174118aa9effSTejun Heo */ 1742c9e7cf27STejun Heo last_pool = get_work_pool(work); 1743fe089f87STejun Heo if (last_pool && last_pool != pool) { 174418aa9effSTejun Heo struct worker *worker; 174518aa9effSTejun Heo 1746a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&last_pool->lock); 174718aa9effSTejun Heo 1748c9e7cf27STejun Heo worker = find_worker_executing_work(last_pool, work); 174918aa9effSTejun Heo 1750112202d9STejun Heo if (worker && worker->current_pwq->wq == wq) { 1751c9178087STejun Heo pwq = worker->current_pwq; 1752fe089f87STejun Heo pool = pwq->pool; 1753fe089f87STejun Heo WARN_ON_ONCE(pool != last_pool); 17548594fadeSLai Jiangshan } else { 175518aa9effSTejun Heo /* meh... not running there, queue here */ 1756a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&last_pool->lock); 1757fe089f87STejun Heo raw_spin_lock(&pool->lock); 175818aa9effSTejun Heo } 17598930cabaSTejun Heo } else { 1760fe089f87STejun Heo raw_spin_lock(&pool->lock); 17618930cabaSTejun Heo } 1762502ca9d8STejun Heo 17639e8cd2f5STejun Heo /* 1764636b927eSTejun Heo * pwq is determined and locked. For unbound pools, we could have raced 1765636b927eSTejun Heo * with pwq release and it could already be dead. If its refcnt is zero, 1766636b927eSTejun Heo * repeat pwq selection. Note that unbound pwqs never die without 1767636b927eSTejun Heo * another pwq replacing it in cpu_pwq or while work items are executing 1768636b927eSTejun Heo * on it, so the retrying is guaranteed to make forward-progress. 17699e8cd2f5STejun Heo */ 17709e8cd2f5STejun Heo if (unlikely(!pwq->refcnt)) { 17719e8cd2f5STejun Heo if (wq->flags & WQ_UNBOUND) { 1772fe089f87STejun Heo raw_spin_unlock(&pool->lock); 17739e8cd2f5STejun Heo cpu_relax(); 17749e8cd2f5STejun Heo goto retry; 17759e8cd2f5STejun Heo } 17769e8cd2f5STejun Heo /* oops */ 17779e8cd2f5STejun Heo WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", 17789e8cd2f5STejun Heo wq->name, cpu); 17799e8cd2f5STejun Heo } 17809e8cd2f5STejun Heo 1781112202d9STejun Heo /* pwq determined, queue */ 1782112202d9STejun Heo trace_workqueue_queue_work(req_cpu, pwq, work); 1783502ca9d8STejun Heo 178424acfb71SThomas Gleixner if (WARN_ON(!list_empty(&work->entry))) 178524acfb71SThomas Gleixner goto out; 17861e19ffc6STejun Heo 1787112202d9STejun Heo pwq->nr_in_flight[pwq->work_color]++; 1788112202d9STejun Heo work_flags = work_color_to_flags(pwq->work_color); 17891e19ffc6STejun Heo 1790112202d9STejun Heo if (likely(pwq->nr_active < pwq->max_active)) { 1791fe089f87STejun Heo if (list_empty(&pool->worklist)) 1792fe089f87STejun Heo pool->watchdog_ts = jiffies; 1793fe089f87STejun Heo 1794cdadf009STejun Heo trace_workqueue_activate_work(work); 1795112202d9STejun Heo pwq->nr_active++; 1796fe089f87STejun Heo insert_work(pwq, work, &pool->worklist, work_flags); 17970219a352STejun Heo kick_pool(pool); 17988a2e8e5dSTejun Heo } else { 1799f97a4a1aSLai Jiangshan work_flags |= WORK_STRUCT_INACTIVE; 1800fe089f87STejun Heo insert_work(pwq, work, &pwq->inactive_works, work_flags); 18018a2e8e5dSTejun Heo } 18021e19ffc6STejun Heo 180324acfb71SThomas Gleixner out: 1804fe089f87STejun Heo raw_spin_unlock(&pool->lock); 180524acfb71SThomas Gleixner rcu_read_unlock(); 18061da177e4SLinus Torvalds } 18071da177e4SLinus Torvalds 18080fcb78c2SRolf Eike Beer /** 1809c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1810c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1811c1a220e7SZhang Rui * @wq: workqueue to use 1812c1a220e7SZhang Rui * @work: work to queue 1813c1a220e7SZhang Rui * 1814c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1815443378f0SPaul E. McKenney * can't go away. Callers that fail to ensure that the specified 1816443378f0SPaul E. McKenney * CPU cannot go away will execute on a randomly chosen CPU. 1817854f5cc5SPaul E. McKenney * But note well that callers specifying a CPU that never has been 1818854f5cc5SPaul E. McKenney * online will get a splat. 1819d185af30SYacine Belkadi * 1820d185af30SYacine Belkadi * Return: %false if @work was already on a queue, %true otherwise. 1821c1a220e7SZhang Rui */ 1822d4283e93STejun Heo bool queue_work_on(int cpu, struct workqueue_struct *wq, 1823d4283e93STejun Heo struct work_struct *work) 1824c1a220e7SZhang Rui { 1825d4283e93STejun Heo bool ret = false; 18268930cabaSTejun Heo unsigned long flags; 18278930cabaSTejun Heo 18288930cabaSTejun Heo local_irq_save(flags); 1829c1a220e7SZhang Rui 183022df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 18314690c4abSTejun Heo __queue_work(cpu, wq, work); 1832d4283e93STejun Heo ret = true; 1833c1a220e7SZhang Rui } 18348930cabaSTejun Heo 18358930cabaSTejun Heo local_irq_restore(flags); 1836c1a220e7SZhang Rui return ret; 1837c1a220e7SZhang Rui } 1838ad7b1f84SMarc Dionne EXPORT_SYMBOL(queue_work_on); 1839c1a220e7SZhang Rui 18408204e0c1SAlexander Duyck /** 1841fef59c9cSTejun Heo * select_numa_node_cpu - Select a CPU based on NUMA node 18428204e0c1SAlexander Duyck * @node: NUMA node ID that we want to select a CPU from 18438204e0c1SAlexander Duyck * 18448204e0c1SAlexander Duyck * This function will attempt to find a "random" cpu available on a given 18458204e0c1SAlexander Duyck * node. If there are no CPUs available on the given node it will return 18468204e0c1SAlexander Duyck * WORK_CPU_UNBOUND indicating that we should just schedule to any 18478204e0c1SAlexander Duyck * available CPU if we need to schedule this work. 18488204e0c1SAlexander Duyck */ 1849fef59c9cSTejun Heo static int select_numa_node_cpu(int node) 18508204e0c1SAlexander Duyck { 18518204e0c1SAlexander Duyck int cpu; 18528204e0c1SAlexander Duyck 18538204e0c1SAlexander Duyck /* Delay binding to CPU if node is not valid or online */ 18548204e0c1SAlexander Duyck if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) 18558204e0c1SAlexander Duyck return WORK_CPU_UNBOUND; 18568204e0c1SAlexander Duyck 18578204e0c1SAlexander Duyck /* Use local node/cpu if we are already there */ 18588204e0c1SAlexander Duyck cpu = raw_smp_processor_id(); 18598204e0c1SAlexander Duyck if (node == cpu_to_node(cpu)) 18608204e0c1SAlexander Duyck return cpu; 18618204e0c1SAlexander Duyck 18628204e0c1SAlexander Duyck /* Use "random" otherwise know as "first" online CPU of node */ 18638204e0c1SAlexander Duyck cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); 18648204e0c1SAlexander Duyck 18658204e0c1SAlexander Duyck /* If CPU is valid return that, otherwise just defer */ 18668204e0c1SAlexander Duyck return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND; 18678204e0c1SAlexander Duyck } 18688204e0c1SAlexander Duyck 18698204e0c1SAlexander Duyck /** 18708204e0c1SAlexander Duyck * queue_work_node - queue work on a "random" cpu for a given NUMA node 18718204e0c1SAlexander Duyck * @node: NUMA node that we are targeting the work for 18728204e0c1SAlexander Duyck * @wq: workqueue to use 18738204e0c1SAlexander Duyck * @work: work to queue 18748204e0c1SAlexander Duyck * 18758204e0c1SAlexander Duyck * We queue the work to a "random" CPU within a given NUMA node. The basic 18768204e0c1SAlexander Duyck * idea here is to provide a way to somehow associate work with a given 18778204e0c1SAlexander Duyck * NUMA node. 18788204e0c1SAlexander Duyck * 18798204e0c1SAlexander Duyck * This function will only make a best effort attempt at getting this onto 18808204e0c1SAlexander Duyck * the right NUMA node. If no node is requested or the requested node is 18818204e0c1SAlexander Duyck * offline then we just fall back to standard queue_work behavior. 18828204e0c1SAlexander Duyck * 18838204e0c1SAlexander Duyck * Currently the "random" CPU ends up being the first available CPU in the 18848204e0c1SAlexander Duyck * intersection of cpu_online_mask and the cpumask of the node, unless we 18858204e0c1SAlexander Duyck * are running on the node. In that case we just use the current CPU. 18868204e0c1SAlexander Duyck * 18878204e0c1SAlexander Duyck * Return: %false if @work was already on a queue, %true otherwise. 18888204e0c1SAlexander Duyck */ 18898204e0c1SAlexander Duyck bool queue_work_node(int node, struct workqueue_struct *wq, 18908204e0c1SAlexander Duyck struct work_struct *work) 18918204e0c1SAlexander Duyck { 18928204e0c1SAlexander Duyck unsigned long flags; 18938204e0c1SAlexander Duyck bool ret = false; 18948204e0c1SAlexander Duyck 18958204e0c1SAlexander Duyck /* 18968204e0c1SAlexander Duyck * This current implementation is specific to unbound workqueues. 18978204e0c1SAlexander Duyck * Specifically we only return the first available CPU for a given 18988204e0c1SAlexander Duyck * node instead of cycling through individual CPUs within the node. 18998204e0c1SAlexander Duyck * 19008204e0c1SAlexander Duyck * If this is used with a per-cpu workqueue then the logic in 19018204e0c1SAlexander Duyck * workqueue_select_cpu_near would need to be updated to allow for 19028204e0c1SAlexander Duyck * some round robin type logic. 19038204e0c1SAlexander Duyck */ 19048204e0c1SAlexander Duyck WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)); 19058204e0c1SAlexander Duyck 19068204e0c1SAlexander Duyck local_irq_save(flags); 19078204e0c1SAlexander Duyck 19088204e0c1SAlexander Duyck if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 1909fef59c9cSTejun Heo int cpu = select_numa_node_cpu(node); 19108204e0c1SAlexander Duyck 19118204e0c1SAlexander Duyck __queue_work(cpu, wq, work); 19128204e0c1SAlexander Duyck ret = true; 19138204e0c1SAlexander Duyck } 19148204e0c1SAlexander Duyck 19158204e0c1SAlexander Duyck local_irq_restore(flags); 19168204e0c1SAlexander Duyck return ret; 19178204e0c1SAlexander Duyck } 19188204e0c1SAlexander Duyck EXPORT_SYMBOL_GPL(queue_work_node); 19198204e0c1SAlexander Duyck 19208c20feb6SKees Cook void delayed_work_timer_fn(struct timer_list *t) 19211da177e4SLinus Torvalds { 19228c20feb6SKees Cook struct delayed_work *dwork = from_timer(dwork, t, timer); 19231da177e4SLinus Torvalds 1924e0aecdd8STejun Heo /* should have been called from irqsafe timer with irq already off */ 192560c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 19261da177e4SLinus Torvalds } 19271438ade5SKonstantin Khlebnikov EXPORT_SYMBOL(delayed_work_timer_fn); 19281da177e4SLinus Torvalds 19297beb2edfSTejun Heo static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 193052bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 19311da177e4SLinus Torvalds { 19327beb2edfSTejun Heo struct timer_list *timer = &dwork->timer; 19337beb2edfSTejun Heo struct work_struct *work = &dwork->work; 19341da177e4SLinus Torvalds 1935637fdbaeSTejun Heo WARN_ON_ONCE(!wq); 19364b243563SSami Tolvanen WARN_ON_ONCE(timer->function != delayed_work_timer_fn); 1937fc4b514fSTejun Heo WARN_ON_ONCE(timer_pending(timer)); 1938fc4b514fSTejun Heo WARN_ON_ONCE(!list_empty(&work->entry)); 19397beb2edfSTejun Heo 19408852aac2STejun Heo /* 19418852aac2STejun Heo * If @delay is 0, queue @dwork->work immediately. This is for 19428852aac2STejun Heo * both optimization and correctness. The earliest @timer can 19438852aac2STejun Heo * expire is on the closest next tick and delayed_work users depend 19448852aac2STejun Heo * on that there's no such delay when @delay is 0. 19458852aac2STejun Heo */ 19468852aac2STejun Heo if (!delay) { 19478852aac2STejun Heo __queue_work(cpu, wq, &dwork->work); 19488852aac2STejun Heo return; 19498852aac2STejun Heo } 19508852aac2STejun Heo 195160c057bcSLai Jiangshan dwork->wq = wq; 19521265057fSTejun Heo dwork->cpu = cpu; 19537beb2edfSTejun Heo timer->expires = jiffies + delay; 19547beb2edfSTejun Heo 1955041bd12eSTejun Heo if (unlikely(cpu != WORK_CPU_UNBOUND)) 19567beb2edfSTejun Heo add_timer_on(timer, cpu); 1957041bd12eSTejun Heo else 1958041bd12eSTejun Heo add_timer(timer); 19597beb2edfSTejun Heo } 19601da177e4SLinus Torvalds 19610fcb78c2SRolf Eike Beer /** 19620fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 19630fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 19640fcb78c2SRolf Eike Beer * @wq: workqueue to use 1965af9997e4SRandy Dunlap * @dwork: work to queue 19660fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 19670fcb78c2SRolf Eike Beer * 1968d185af30SYacine Belkadi * Return: %false if @work was already on a queue, %true otherwise. If 1969715f1300STejun Heo * @delay is zero and @dwork is idle, it will be scheduled for immediate 1970715f1300STejun Heo * execution. 19710fcb78c2SRolf Eike Beer */ 1972d4283e93STejun Heo bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 197352bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 19747a6bc1cdSVenkatesh Pallipadi { 197552bad64dSDavid Howells struct work_struct *work = &dwork->work; 1976d4283e93STejun Heo bool ret = false; 19778930cabaSTejun Heo unsigned long flags; 19788930cabaSTejun Heo 19798930cabaSTejun Heo /* read the comment in __queue_work() */ 19808930cabaSTejun Heo local_irq_save(flags); 19817a6bc1cdSVenkatesh Pallipadi 198222df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 19837beb2edfSTejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 1984d4283e93STejun Heo ret = true; 19857a6bc1cdSVenkatesh Pallipadi } 19868930cabaSTejun Heo 19878930cabaSTejun Heo local_irq_restore(flags); 19887a6bc1cdSVenkatesh Pallipadi return ret; 19897a6bc1cdSVenkatesh Pallipadi } 1990ad7b1f84SMarc Dionne EXPORT_SYMBOL(queue_delayed_work_on); 19911da177e4SLinus Torvalds 1992c8e55f36STejun Heo /** 19938376fe22STejun Heo * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 19948376fe22STejun Heo * @cpu: CPU number to execute work on 19958376fe22STejun Heo * @wq: workqueue to use 19968376fe22STejun Heo * @dwork: work to queue 19978376fe22STejun Heo * @delay: number of jiffies to wait before queueing 19988376fe22STejun Heo * 19998376fe22STejun Heo * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 20008376fe22STejun Heo * modify @dwork's timer so that it expires after @delay. If @delay is 20018376fe22STejun Heo * zero, @work is guaranteed to be scheduled immediately regardless of its 20028376fe22STejun Heo * current state. 20038376fe22STejun Heo * 2004d185af30SYacine Belkadi * Return: %false if @dwork was idle and queued, %true if @dwork was 20058376fe22STejun Heo * pending and its timer was modified. 20068376fe22STejun Heo * 2007e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 20088376fe22STejun Heo * See try_to_grab_pending() for details. 20098376fe22STejun Heo */ 20108376fe22STejun Heo bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 20118376fe22STejun Heo struct delayed_work *dwork, unsigned long delay) 20128376fe22STejun Heo { 20138376fe22STejun Heo unsigned long flags; 20148376fe22STejun Heo int ret; 20158376fe22STejun Heo 20168376fe22STejun Heo do { 20178376fe22STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 20188376fe22STejun Heo } while (unlikely(ret == -EAGAIN)); 20198376fe22STejun Heo 20208376fe22STejun Heo if (likely(ret >= 0)) { 20218376fe22STejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 20228376fe22STejun Heo local_irq_restore(flags); 20238376fe22STejun Heo } 20248376fe22STejun Heo 20258376fe22STejun Heo /* -ENOENT from try_to_grab_pending() becomes %true */ 20268376fe22STejun Heo return ret; 20278376fe22STejun Heo } 20288376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work_on); 20298376fe22STejun Heo 203005f0fe6bSTejun Heo static void rcu_work_rcufn(struct rcu_head *rcu) 203105f0fe6bSTejun Heo { 203205f0fe6bSTejun Heo struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu); 203305f0fe6bSTejun Heo 203405f0fe6bSTejun Heo /* read the comment in __queue_work() */ 203505f0fe6bSTejun Heo local_irq_disable(); 203605f0fe6bSTejun Heo __queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work); 203705f0fe6bSTejun Heo local_irq_enable(); 203805f0fe6bSTejun Heo } 203905f0fe6bSTejun Heo 204005f0fe6bSTejun Heo /** 204105f0fe6bSTejun Heo * queue_rcu_work - queue work after a RCU grace period 204205f0fe6bSTejun Heo * @wq: workqueue to use 204305f0fe6bSTejun Heo * @rwork: work to queue 204405f0fe6bSTejun Heo * 204505f0fe6bSTejun Heo * Return: %false if @rwork was already pending, %true otherwise. Note 204605f0fe6bSTejun Heo * that a full RCU grace period is guaranteed only after a %true return. 2047bf393fd4SBart Van Assche * While @rwork is guaranteed to be executed after a %false return, the 204805f0fe6bSTejun Heo * execution may happen before a full RCU grace period has passed. 204905f0fe6bSTejun Heo */ 205005f0fe6bSTejun Heo bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) 205105f0fe6bSTejun Heo { 205205f0fe6bSTejun Heo struct work_struct *work = &rwork->work; 205305f0fe6bSTejun Heo 205405f0fe6bSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 205505f0fe6bSTejun Heo rwork->wq = wq; 2056a7e30c0eSUladzislau Rezki call_rcu_hurry(&rwork->rcu, rcu_work_rcufn); 205705f0fe6bSTejun Heo return true; 205805f0fe6bSTejun Heo } 205905f0fe6bSTejun Heo 206005f0fe6bSTejun Heo return false; 206105f0fe6bSTejun Heo } 206205f0fe6bSTejun Heo EXPORT_SYMBOL(queue_rcu_work); 206305f0fe6bSTejun Heo 2064f7537df5SLai Jiangshan static struct worker *alloc_worker(int node) 2065c34056a3STejun Heo { 2066c34056a3STejun Heo struct worker *worker; 2067c34056a3STejun Heo 2068f7537df5SLai Jiangshan worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); 2069c8e55f36STejun Heo if (worker) { 2070c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 2071affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 2072da028469SLai Jiangshan INIT_LIST_HEAD(&worker->node); 2073e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 2074e22bee78STejun Heo worker->flags = WORKER_PREP; 2075c8e55f36STejun Heo } 2076c34056a3STejun Heo return worker; 2077c34056a3STejun Heo } 2078c34056a3STejun Heo 20799546b29eSTejun Heo static cpumask_t *pool_allowed_cpus(struct worker_pool *pool) 20809546b29eSTejun Heo { 20818639ecebSTejun Heo if (pool->cpu < 0 && pool->attrs->affn_strict) 20829546b29eSTejun Heo return pool->attrs->__pod_cpumask; 20838639ecebSTejun Heo else 20848639ecebSTejun Heo return pool->attrs->cpumask; 20859546b29eSTejun Heo } 20869546b29eSTejun Heo 2087c34056a3STejun Heo /** 20884736cbf7SLai Jiangshan * worker_attach_to_pool() - attach a worker to a pool 20894736cbf7SLai Jiangshan * @worker: worker to be attached 20904736cbf7SLai Jiangshan * @pool: the target pool 20914736cbf7SLai Jiangshan * 20924736cbf7SLai Jiangshan * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and 20934736cbf7SLai Jiangshan * cpu-binding of @worker are kept coordinated with the pool across 20944736cbf7SLai Jiangshan * cpu-[un]hotplugs. 20954736cbf7SLai Jiangshan */ 20964736cbf7SLai Jiangshan static void worker_attach_to_pool(struct worker *worker, 20974736cbf7SLai Jiangshan struct worker_pool *pool) 20984736cbf7SLai Jiangshan { 20991258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 21004736cbf7SLai Jiangshan 21014736cbf7SLai Jiangshan /* 21021258fae7STejun Heo * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains 21031258fae7STejun Heo * stable across this function. See the comments above the flag 21041258fae7STejun Heo * definition for details. 21054736cbf7SLai Jiangshan */ 21064736cbf7SLai Jiangshan if (pool->flags & POOL_DISASSOCIATED) 21074736cbf7SLai Jiangshan worker->flags |= WORKER_UNBOUND; 21085c25b5ffSPeter Zijlstra else 21095c25b5ffSPeter Zijlstra kthread_set_per_cpu(worker->task, pool->cpu); 21104736cbf7SLai Jiangshan 2111640f17c8SPeter Zijlstra if (worker->rescue_wq) 21129546b29eSTejun Heo set_cpus_allowed_ptr(worker->task, pool_allowed_cpus(pool)); 2113640f17c8SPeter Zijlstra 21144736cbf7SLai Jiangshan list_add_tail(&worker->node, &pool->workers); 2115a2d812a2STejun Heo worker->pool = pool; 21164736cbf7SLai Jiangshan 21171258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 21184736cbf7SLai Jiangshan } 21194736cbf7SLai Jiangshan 21204736cbf7SLai Jiangshan /** 212160f5a4bcSLai Jiangshan * worker_detach_from_pool() - detach a worker from its pool 212260f5a4bcSLai Jiangshan * @worker: worker which is attached to its pool 212360f5a4bcSLai Jiangshan * 21244736cbf7SLai Jiangshan * Undo the attaching which had been done in worker_attach_to_pool(). The 21254736cbf7SLai Jiangshan * caller worker shouldn't access to the pool after detached except it has 21264736cbf7SLai Jiangshan * other reference to the pool. 212760f5a4bcSLai Jiangshan */ 2128a2d812a2STejun Heo static void worker_detach_from_pool(struct worker *worker) 212960f5a4bcSLai Jiangshan { 2130a2d812a2STejun Heo struct worker_pool *pool = worker->pool; 213160f5a4bcSLai Jiangshan struct completion *detach_completion = NULL; 213260f5a4bcSLai Jiangshan 21331258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 2134a2d812a2STejun Heo 21355c25b5ffSPeter Zijlstra kthread_set_per_cpu(worker->task, -1); 2136da028469SLai Jiangshan list_del(&worker->node); 2137a2d812a2STejun Heo worker->pool = NULL; 2138a2d812a2STejun Heo 2139e02b9312SValentin Schneider if (list_empty(&pool->workers) && list_empty(&pool->dying_workers)) 214060f5a4bcSLai Jiangshan detach_completion = pool->detach_completion; 21411258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 214260f5a4bcSLai Jiangshan 2143b62c0751SLai Jiangshan /* clear leftover flags without pool->lock after it is detached */ 2144b62c0751SLai Jiangshan worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); 2145b62c0751SLai Jiangshan 214660f5a4bcSLai Jiangshan if (detach_completion) 214760f5a4bcSLai Jiangshan complete(detach_completion); 214860f5a4bcSLai Jiangshan } 214960f5a4bcSLai Jiangshan 215060f5a4bcSLai Jiangshan /** 2151c34056a3STejun Heo * create_worker - create a new workqueue worker 215263d95a91STejun Heo * @pool: pool the new worker will belong to 2153c34056a3STejun Heo * 2154051e1850SLai Jiangshan * Create and start a new worker which is attached to @pool. 2155c34056a3STejun Heo * 2156c34056a3STejun Heo * CONTEXT: 2157c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 2158c34056a3STejun Heo * 2159d185af30SYacine Belkadi * Return: 2160c34056a3STejun Heo * Pointer to the newly created worker. 2161c34056a3STejun Heo */ 2162bc2ae0f5STejun Heo static struct worker *create_worker(struct worker_pool *pool) 2163c34056a3STejun Heo { 2164e441b56fSZhen Lei struct worker *worker; 2165e441b56fSZhen Lei int id; 21665d9c7a1eSLucy Mielke char id_buf[23]; 2167c34056a3STejun Heo 21687cda9aaeSLai Jiangshan /* ID is needed to determine kthread name */ 2169e441b56fSZhen Lei id = ida_alloc(&pool->worker_ida, GFP_KERNEL); 21703f0ea0b8SPetr Mladek if (id < 0) { 21713f0ea0b8SPetr Mladek pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n", 21723f0ea0b8SPetr Mladek ERR_PTR(id)); 2173e441b56fSZhen Lei return NULL; 21743f0ea0b8SPetr Mladek } 2175c34056a3STejun Heo 2176f7537df5SLai Jiangshan worker = alloc_worker(pool->node); 21773f0ea0b8SPetr Mladek if (!worker) { 21783f0ea0b8SPetr Mladek pr_err_once("workqueue: Failed to allocate a worker\n"); 2179c34056a3STejun Heo goto fail; 21803f0ea0b8SPetr Mladek } 2181c34056a3STejun Heo 2182c34056a3STejun Heo worker->id = id; 2183c34056a3STejun Heo 218429c91e99STejun Heo if (pool->cpu >= 0) 2185e3c916a4STejun Heo snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, 2186e3c916a4STejun Heo pool->attrs->nice < 0 ? "H" : ""); 2187f3421797STejun Heo else 2188e3c916a4STejun Heo snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); 2189e3c916a4STejun Heo 2190f3f90ad4STejun Heo worker->task = kthread_create_on_node(worker_thread, worker, pool->node, 2191e3c916a4STejun Heo "kworker/%s", id_buf); 21923f0ea0b8SPetr Mladek if (IS_ERR(worker->task)) { 219360f54038SPetr Mladek if (PTR_ERR(worker->task) == -EINTR) { 219460f54038SPetr Mladek pr_err("workqueue: Interrupted when creating a worker thread \"kworker/%s\"\n", 219560f54038SPetr Mladek id_buf); 219660f54038SPetr Mladek } else { 21973f0ea0b8SPetr Mladek pr_err_once("workqueue: Failed to create a worker thread: %pe", 21983f0ea0b8SPetr Mladek worker->task); 219960f54038SPetr Mladek } 2200c34056a3STejun Heo goto fail; 22013f0ea0b8SPetr Mladek } 2202c34056a3STejun Heo 220391151228SOleg Nesterov set_user_nice(worker->task, pool->attrs->nice); 22049546b29eSTejun Heo kthread_bind_mask(worker->task, pool_allowed_cpus(pool)); 220591151228SOleg Nesterov 2206da028469SLai Jiangshan /* successful, attach the worker to the pool */ 22074736cbf7SLai Jiangshan worker_attach_to_pool(worker, pool); 2208822d8405STejun Heo 2209051e1850SLai Jiangshan /* start the newly created worker */ 2210a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 22110219a352STejun Heo 2212051e1850SLai Jiangshan worker->pool->nr_workers++; 2213051e1850SLai Jiangshan worker_enter_idle(worker); 22140219a352STejun Heo kick_pool(pool); 22150219a352STejun Heo 22160219a352STejun Heo /* 22170219a352STejun Heo * @worker is waiting on a completion in kthread() and will trigger hung 22180219a352STejun Heo * check if not woken up soon. As kick_pool() might not have waken it 22190219a352STejun Heo * up, wake it up explicitly once more. 22200219a352STejun Heo */ 2221051e1850SLai Jiangshan wake_up_process(worker->task); 22220219a352STejun Heo 2223a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2224051e1850SLai Jiangshan 2225c34056a3STejun Heo return worker; 2226822d8405STejun Heo 2227c34056a3STejun Heo fail: 2228e441b56fSZhen Lei ida_free(&pool->worker_ida, id); 2229c34056a3STejun Heo kfree(worker); 2230c34056a3STejun Heo return NULL; 2231c34056a3STejun Heo } 2232c34056a3STejun Heo 2233793777bcSValentin Schneider static void unbind_worker(struct worker *worker) 2234793777bcSValentin Schneider { 2235793777bcSValentin Schneider lockdep_assert_held(&wq_pool_attach_mutex); 2236793777bcSValentin Schneider 2237793777bcSValentin Schneider kthread_set_per_cpu(worker->task, -1); 2238793777bcSValentin Schneider if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) 2239793777bcSValentin Schneider WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0); 2240793777bcSValentin Schneider else 2241793777bcSValentin Schneider WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); 2242793777bcSValentin Schneider } 2243793777bcSValentin Schneider 2244e02b9312SValentin Schneider static void wake_dying_workers(struct list_head *cull_list) 2245e02b9312SValentin Schneider { 2246e02b9312SValentin Schneider struct worker *worker, *tmp; 2247e02b9312SValentin Schneider 2248e02b9312SValentin Schneider list_for_each_entry_safe(worker, tmp, cull_list, entry) { 2249e02b9312SValentin Schneider list_del_init(&worker->entry); 2250e02b9312SValentin Schneider unbind_worker(worker); 2251e02b9312SValentin Schneider /* 2252e02b9312SValentin Schneider * If the worker was somehow already running, then it had to be 2253e02b9312SValentin Schneider * in pool->idle_list when set_worker_dying() happened or we 2254e02b9312SValentin Schneider * wouldn't have gotten here. 2255c34056a3STejun Heo * 2256e02b9312SValentin Schneider * Thus, the worker must either have observed the WORKER_DIE 2257e02b9312SValentin Schneider * flag, or have set its state to TASK_IDLE. Either way, the 2258e02b9312SValentin Schneider * below will be observed by the worker and is safe to do 2259e02b9312SValentin Schneider * outside of pool->lock. 2260e02b9312SValentin Schneider */ 2261e02b9312SValentin Schneider wake_up_process(worker->task); 2262e02b9312SValentin Schneider } 2263e02b9312SValentin Schneider } 2264e02b9312SValentin Schneider 2265e02b9312SValentin Schneider /** 2266e02b9312SValentin Schneider * set_worker_dying - Tag a worker for destruction 2267e02b9312SValentin Schneider * @worker: worker to be destroyed 2268e02b9312SValentin Schneider * @list: transfer worker away from its pool->idle_list and into list 2269e02b9312SValentin Schneider * 2270e02b9312SValentin Schneider * Tag @worker for destruction and adjust @pool stats accordingly. The worker 2271e02b9312SValentin Schneider * should be idle. 2272c8e55f36STejun Heo * 2273c8e55f36STejun Heo * CONTEXT: 2274a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 2275c34056a3STejun Heo */ 2276e02b9312SValentin Schneider static void set_worker_dying(struct worker *worker, struct list_head *list) 2277c34056a3STejun Heo { 2278bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2279c34056a3STejun Heo 2280cd549687STejun Heo lockdep_assert_held(&pool->lock); 2281e02b9312SValentin Schneider lockdep_assert_held(&wq_pool_attach_mutex); 2282cd549687STejun Heo 2283c34056a3STejun Heo /* sanity check frenzy */ 22846183c009STejun Heo if (WARN_ON(worker->current_work) || 228573eb7fe7SLai Jiangshan WARN_ON(!list_empty(&worker->scheduled)) || 228673eb7fe7SLai Jiangshan WARN_ON(!(worker->flags & WORKER_IDLE))) 22876183c009STejun Heo return; 2288c34056a3STejun Heo 2289bd7bdd43STejun Heo pool->nr_workers--; 2290bd7bdd43STejun Heo pool->nr_idle--; 2291c8e55f36STejun Heo 2292cb444766STejun Heo worker->flags |= WORKER_DIE; 2293e02b9312SValentin Schneider 2294e02b9312SValentin Schneider list_move(&worker->entry, list); 2295e02b9312SValentin Schneider list_move(&worker->node, &pool->dying_workers); 2296c34056a3STejun Heo } 2297c34056a3STejun Heo 22983f959aa3SValentin Schneider /** 22993f959aa3SValentin Schneider * idle_worker_timeout - check if some idle workers can now be deleted. 23003f959aa3SValentin Schneider * @t: The pool's idle_timer that just expired 23013f959aa3SValentin Schneider * 23023f959aa3SValentin Schneider * The timer is armed in worker_enter_idle(). Note that it isn't disarmed in 23033f959aa3SValentin Schneider * worker_leave_idle(), as a worker flicking between idle and active while its 23043f959aa3SValentin Schneider * pool is at the too_many_workers() tipping point would cause too much timer 23053f959aa3SValentin Schneider * housekeeping overhead. Since IDLE_WORKER_TIMEOUT is long enough, we just let 23063f959aa3SValentin Schneider * it expire and re-evaluate things from there. 23073f959aa3SValentin Schneider */ 230832a6c723SKees Cook static void idle_worker_timeout(struct timer_list *t) 2309e22bee78STejun Heo { 231032a6c723SKees Cook struct worker_pool *pool = from_timer(pool, t, idle_timer); 23113f959aa3SValentin Schneider bool do_cull = false; 23123f959aa3SValentin Schneider 23133f959aa3SValentin Schneider if (work_pending(&pool->idle_cull_work)) 23143f959aa3SValentin Schneider return; 23153f959aa3SValentin Schneider 23163f959aa3SValentin Schneider raw_spin_lock_irq(&pool->lock); 23173f959aa3SValentin Schneider 23183f959aa3SValentin Schneider if (too_many_workers(pool)) { 23193f959aa3SValentin Schneider struct worker *worker; 23203f959aa3SValentin Schneider unsigned long expires; 23213f959aa3SValentin Schneider 23223f959aa3SValentin Schneider /* idle_list is kept in LIFO order, check the last one */ 23233f959aa3SValentin Schneider worker = list_entry(pool->idle_list.prev, struct worker, entry); 23243f959aa3SValentin Schneider expires = worker->last_active + IDLE_WORKER_TIMEOUT; 23253f959aa3SValentin Schneider do_cull = !time_before(jiffies, expires); 23263f959aa3SValentin Schneider 23273f959aa3SValentin Schneider if (!do_cull) 23283f959aa3SValentin Schneider mod_timer(&pool->idle_timer, expires); 23293f959aa3SValentin Schneider } 23303f959aa3SValentin Schneider raw_spin_unlock_irq(&pool->lock); 23313f959aa3SValentin Schneider 23323f959aa3SValentin Schneider if (do_cull) 23333f959aa3SValentin Schneider queue_work(system_unbound_wq, &pool->idle_cull_work); 23343f959aa3SValentin Schneider } 23353f959aa3SValentin Schneider 23363f959aa3SValentin Schneider /** 23373f959aa3SValentin Schneider * idle_cull_fn - cull workers that have been idle for too long. 23383f959aa3SValentin Schneider * @work: the pool's work for handling these idle workers 23393f959aa3SValentin Schneider * 23403f959aa3SValentin Schneider * This goes through a pool's idle workers and gets rid of those that have been 23413f959aa3SValentin Schneider * idle for at least IDLE_WORKER_TIMEOUT seconds. 2342e02b9312SValentin Schneider * 2343e02b9312SValentin Schneider * We don't want to disturb isolated CPUs because of a pcpu kworker being 2344e02b9312SValentin Schneider * culled, so this also resets worker affinity. This requires a sleepable 2345e02b9312SValentin Schneider * context, hence the split between timer callback and work item. 23463f959aa3SValentin Schneider */ 23473f959aa3SValentin Schneider static void idle_cull_fn(struct work_struct *work) 23483f959aa3SValentin Schneider { 23493f959aa3SValentin Schneider struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work); 23509680540cSYang Yingliang LIST_HEAD(cull_list); 2351e22bee78STejun Heo 2352e02b9312SValentin Schneider /* 2353e02b9312SValentin Schneider * Grabbing wq_pool_attach_mutex here ensures an already-running worker 2354e02b9312SValentin Schneider * cannot proceed beyong worker_detach_from_pool() in its self-destruct 2355e02b9312SValentin Schneider * path. This is required as a previously-preempted worker could run after 2356e02b9312SValentin Schneider * set_worker_dying() has happened but before wake_dying_workers() did. 2357e02b9312SValentin Schneider */ 2358e02b9312SValentin Schneider mutex_lock(&wq_pool_attach_mutex); 2359a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2360e22bee78STejun Heo 23613347fc9fSLai Jiangshan while (too_many_workers(pool)) { 2362e22bee78STejun Heo struct worker *worker; 2363e22bee78STejun Heo unsigned long expires; 2364e22bee78STejun Heo 236563d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 2366e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 2367e22bee78STejun Heo 23683347fc9fSLai Jiangshan if (time_before(jiffies, expires)) { 236963d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 23703347fc9fSLai Jiangshan break; 2371e22bee78STejun Heo } 23723347fc9fSLai Jiangshan 2373e02b9312SValentin Schneider set_worker_dying(worker, &cull_list); 2374e22bee78STejun Heo } 2375e22bee78STejun Heo 2376a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2377e02b9312SValentin Schneider wake_dying_workers(&cull_list); 2378e02b9312SValentin Schneider mutex_unlock(&wq_pool_attach_mutex); 2379e22bee78STejun Heo } 2380e22bee78STejun Heo 2381493a1724STejun Heo static void send_mayday(struct work_struct *work) 2382e22bee78STejun Heo { 2383112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2384112202d9STejun Heo struct workqueue_struct *wq = pwq->wq; 2385493a1724STejun Heo 23862e109a28STejun Heo lockdep_assert_held(&wq_mayday_lock); 2387e22bee78STejun Heo 2388493008a8STejun Heo if (!wq->rescuer) 2389493a1724STejun Heo return; 2390e22bee78STejun Heo 2391e22bee78STejun Heo /* mayday mayday mayday */ 2392493a1724STejun Heo if (list_empty(&pwq->mayday_node)) { 239377668c8bSLai Jiangshan /* 239477668c8bSLai Jiangshan * If @pwq is for an unbound wq, its base ref may be put at 239577668c8bSLai Jiangshan * any time due to an attribute change. Pin @pwq until the 239677668c8bSLai Jiangshan * rescuer is done with it. 239777668c8bSLai Jiangshan */ 239877668c8bSLai Jiangshan get_pwq(pwq); 2399493a1724STejun Heo list_add_tail(&pwq->mayday_node, &wq->maydays); 2400e22bee78STejun Heo wake_up_process(wq->rescuer->task); 2401725e8ec5STejun Heo pwq->stats[PWQ_STAT_MAYDAY]++; 2402493a1724STejun Heo } 2403e22bee78STejun Heo } 2404e22bee78STejun Heo 240532a6c723SKees Cook static void pool_mayday_timeout(struct timer_list *t) 2406e22bee78STejun Heo { 240732a6c723SKees Cook struct worker_pool *pool = from_timer(pool, t, mayday_timer); 2408e22bee78STejun Heo struct work_struct *work; 2409e22bee78STejun Heo 2410a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2411a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */ 2412e22bee78STejun Heo 241363d95a91STejun Heo if (need_to_create_worker(pool)) { 2414e22bee78STejun Heo /* 2415e22bee78STejun Heo * We've been trying to create a new worker but 2416e22bee78STejun Heo * haven't been successful. We might be hitting an 2417e22bee78STejun Heo * allocation deadlock. Send distress signals to 2418e22bee78STejun Heo * rescuers. 2419e22bee78STejun Heo */ 242063d95a91STejun Heo list_for_each_entry(work, &pool->worklist, entry) 2421e22bee78STejun Heo send_mayday(work); 2422e22bee78STejun Heo } 2423e22bee78STejun Heo 2424a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&wq_mayday_lock); 2425a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2426e22bee78STejun Heo 242763d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 2428e22bee78STejun Heo } 2429e22bee78STejun Heo 2430e22bee78STejun Heo /** 2431e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 243263d95a91STejun Heo * @pool: pool to create a new worker for 2433e22bee78STejun Heo * 243463d95a91STejun Heo * Create a new worker for @pool if necessary. @pool is guaranteed to 2435e22bee78STejun Heo * have at least one idle worker on return from this function. If 2436e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 243763d95a91STejun Heo * sent to all rescuers with works scheduled on @pool to resolve 2438e22bee78STejun Heo * possible allocation deadlock. 2439e22bee78STejun Heo * 2440c5aa87bbSTejun Heo * On return, need_to_create_worker() is guaranteed to be %false and 2441c5aa87bbSTejun Heo * may_start_working() %true. 2442e22bee78STejun Heo * 2443e22bee78STejun Heo * LOCKING: 2444a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 2445e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 2446e22bee78STejun Heo * manager. 2447e22bee78STejun Heo */ 244829187a9eSTejun Heo static void maybe_create_worker(struct worker_pool *pool) 2449d565ed63STejun Heo __releases(&pool->lock) 2450d565ed63STejun Heo __acquires(&pool->lock) 2451e22bee78STejun Heo { 2452e22bee78STejun Heo restart: 2453a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 24549f9c2364STejun Heo 2455e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 245663d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 2457e22bee78STejun Heo 2458e22bee78STejun Heo while (true) { 2459051e1850SLai Jiangshan if (create_worker(pool) || !need_to_create_worker(pool)) 2460e22bee78STejun Heo break; 2461e22bee78STejun Heo 2462e212f361SLai Jiangshan schedule_timeout_interruptible(CREATE_COOLDOWN); 24639f9c2364STejun Heo 246463d95a91STejun Heo if (!need_to_create_worker(pool)) 2465e22bee78STejun Heo break; 2466e22bee78STejun Heo } 2467e22bee78STejun Heo 246863d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 2469a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2470051e1850SLai Jiangshan /* 2471051e1850SLai Jiangshan * This is necessary even after a new worker was just successfully 2472051e1850SLai Jiangshan * created as @pool->lock was dropped and the new worker might have 2473051e1850SLai Jiangshan * already become busy. 2474051e1850SLai Jiangshan */ 247563d95a91STejun Heo if (need_to_create_worker(pool)) 2476e22bee78STejun Heo goto restart; 2477e22bee78STejun Heo } 2478e22bee78STejun Heo 2479e22bee78STejun Heo /** 2480e22bee78STejun Heo * manage_workers - manage worker pool 2481e22bee78STejun Heo * @worker: self 2482e22bee78STejun Heo * 2483706026c2STejun Heo * Assume the manager role and manage the worker pool @worker belongs 2484e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 2485706026c2STejun Heo * pool. The exclusion is handled automatically by this function. 2486e22bee78STejun Heo * 2487e22bee78STejun Heo * The caller can safely start processing works on false return. On 2488e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 2489e22bee78STejun Heo * and may_start_working() is true. 2490e22bee78STejun Heo * 2491e22bee78STejun Heo * CONTEXT: 2492a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 2493e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 2494e22bee78STejun Heo * 2495d185af30SYacine Belkadi * Return: 249629187a9eSTejun Heo * %false if the pool doesn't need management and the caller can safely 249729187a9eSTejun Heo * start processing works, %true if management function was performed and 249829187a9eSTejun Heo * the conditions that the caller verified before calling the function may 249929187a9eSTejun Heo * no longer be true. 2500e22bee78STejun Heo */ 2501e22bee78STejun Heo static bool manage_workers(struct worker *worker) 2502e22bee78STejun Heo { 250363d95a91STejun Heo struct worker_pool *pool = worker->pool; 2504e22bee78STejun Heo 2505692b4825STejun Heo if (pool->flags & POOL_MANAGER_ACTIVE) 250629187a9eSTejun Heo return false; 2507692b4825STejun Heo 2508692b4825STejun Heo pool->flags |= POOL_MANAGER_ACTIVE; 25092607d7a6STejun Heo pool->manager = worker; 2510e22bee78STejun Heo 251129187a9eSTejun Heo maybe_create_worker(pool); 2512e22bee78STejun Heo 25132607d7a6STejun Heo pool->manager = NULL; 2514692b4825STejun Heo pool->flags &= ~POOL_MANAGER_ACTIVE; 2515d8bb65abSSebastian Andrzej Siewior rcuwait_wake_up(&manager_wait); 251629187a9eSTejun Heo return true; 2517e22bee78STejun Heo } 2518e22bee78STejun Heo 2519a62428c0STejun Heo /** 2520a62428c0STejun Heo * process_one_work - process single work 2521c34056a3STejun Heo * @worker: self 2522a62428c0STejun Heo * @work: work to process 2523a62428c0STejun Heo * 2524a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 2525a62428c0STejun Heo * process a single work including synchronization against and 2526a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 2527a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 2528a62428c0STejun Heo * call this function to process a work. 2529a62428c0STejun Heo * 2530a62428c0STejun Heo * CONTEXT: 2531a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) which is released and regrabbed. 2532a62428c0STejun Heo */ 2533c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 2534d565ed63STejun Heo __releases(&pool->lock) 2535d565ed63STejun Heo __acquires(&pool->lock) 25361da177e4SLinus Torvalds { 2537112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2538bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2539c4560c2cSLai Jiangshan unsigned long work_data; 25404e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 25414e6045f1SJohannes Berg /* 2542a62428c0STejun Heo * It is permissible to free the struct work_struct from 2543a62428c0STejun Heo * inside the function that is called from it, this we need to 2544a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 2545a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 2546a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 25474e6045f1SJohannes Berg */ 25484d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 25494d82a1deSPeter Zijlstra 25504d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 25514e6045f1SJohannes Berg #endif 2552807407c0SLai Jiangshan /* ensure we're on the correct CPU */ 255385327af6SLai Jiangshan WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 2554ec22ca5eSTejun Heo raw_smp_processor_id() != pool->cpu); 255525511a47STejun Heo 25568930cabaSTejun Heo /* claim and dequeue */ 2557dc186ad7SThomas Gleixner debug_work_deactivate(work); 2558c9e7cf27STejun Heo hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); 2559c34056a3STejun Heo worker->current_work = work; 2560a2c1c57bSTejun Heo worker->current_func = work->func; 2561112202d9STejun Heo worker->current_pwq = pwq; 2562616db877STejun Heo worker->current_at = worker->task->se.sum_exec_runtime; 2563c4560c2cSLai Jiangshan work_data = *work_data_bits(work); 2564d812796eSLai Jiangshan worker->current_color = get_work_color(work_data); 25657a22ad75STejun Heo 25668bf89593STejun Heo /* 25678bf89593STejun Heo * Record wq name for cmdline and debug reporting, may get 25688bf89593STejun Heo * overridden through set_worker_desc(). 25698bf89593STejun Heo */ 25708bf89593STejun Heo strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN); 25718bf89593STejun Heo 2572a62428c0STejun Heo list_del_init(&work->entry); 2573a62428c0STejun Heo 2574649027d7STejun Heo /* 2575228f1d00SLai Jiangshan * CPU intensive works don't participate in concurrency management. 2576228f1d00SLai Jiangshan * They're the scheduler's responsibility. This takes @worker out 2577228f1d00SLai Jiangshan * of concurrency management and the next code block will chain 2578228f1d00SLai Jiangshan * execution of the pending work items. 2579fb0e7bebSTejun Heo */ 2580616db877STejun Heo if (unlikely(pwq->wq->flags & WQ_CPU_INTENSIVE)) 2581228f1d00SLai Jiangshan worker_set_flags(worker, WORKER_CPU_INTENSIVE); 2582fb0e7bebSTejun Heo 2583974271c4STejun Heo /* 25840219a352STejun Heo * Kick @pool if necessary. It's always noop for per-cpu worker pools 25850219a352STejun Heo * since nr_running would always be >= 1 at this point. This is used to 25860219a352STejun Heo * chain execution of the pending work items for WORKER_NOT_RUNNING 25870219a352STejun Heo * workers such as the UNBOUND and CPU_INTENSIVE ones. 2588974271c4STejun Heo */ 25890219a352STejun Heo kick_pool(pool); 2590974271c4STejun Heo 25918930cabaSTejun Heo /* 25927c3eed5cSTejun Heo * Record the last pool and clear PENDING which should be the last 2593d565ed63STejun Heo * update to @work. Also, do this inside @pool->lock so that 259423657bb1STejun Heo * PENDING and queued state changes happen together while IRQ is 259523657bb1STejun Heo * disabled. 25968930cabaSTejun Heo */ 25977c3eed5cSTejun Heo set_work_pool_and_clear_pending(work, pool->id); 25981da177e4SLinus Torvalds 2599fe48ba7dSMirsad Goran Todorovac pwq->stats[PWQ_STAT_STARTED]++; 2600a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2601365970a1SDavid Howells 2602a1d14934SPeter Zijlstra lock_map_acquire(&pwq->wq->lockdep_map); 26033295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 2604e6f3faa7SPeter Zijlstra /* 2605f52be570SPeter Zijlstra * Strictly speaking we should mark the invariant state without holding 2606f52be570SPeter Zijlstra * any locks, that is, before these two lock_map_acquire()'s. 2607e6f3faa7SPeter Zijlstra * 2608e6f3faa7SPeter Zijlstra * However, that would result in: 2609e6f3faa7SPeter Zijlstra * 2610e6f3faa7SPeter Zijlstra * A(W1) 2611e6f3faa7SPeter Zijlstra * WFC(C) 2612e6f3faa7SPeter Zijlstra * A(W1) 2613e6f3faa7SPeter Zijlstra * C(C) 2614e6f3faa7SPeter Zijlstra * 2615e6f3faa7SPeter Zijlstra * Which would create W1->C->W1 dependencies, even though there is no 2616e6f3faa7SPeter Zijlstra * actual deadlock possible. There are two solutions, using a 2617e6f3faa7SPeter Zijlstra * read-recursive acquire on the work(queue) 'locks', but this will then 2618f52be570SPeter Zijlstra * hit the lockdep limitation on recursive locks, or simply discard 2619e6f3faa7SPeter Zijlstra * these locks. 2620e6f3faa7SPeter Zijlstra * 2621e6f3faa7SPeter Zijlstra * AFAICT there is no possible deadlock scenario between the 2622e6f3faa7SPeter Zijlstra * flush_work() and complete() primitives (except for single-threaded 2623e6f3faa7SPeter Zijlstra * workqueues), so hiding them isn't a problem. 2624e6f3faa7SPeter Zijlstra */ 2625f52be570SPeter Zijlstra lockdep_invariant_state(true); 2626e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 2627a2c1c57bSTejun Heo worker->current_func(work); 2628e36c886aSArjan van de Ven /* 2629e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 2630e36c886aSArjan van de Ven * point will only record its address. 2631e36c886aSArjan van de Ven */ 26321c5da0ecSDaniel Jordan trace_workqueue_execute_end(work, worker->current_func); 2633725e8ec5STejun Heo pwq->stats[PWQ_STAT_COMPLETED]++; 26343295f0efSIngo Molnar lock_map_release(&lockdep_map); 2635112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 26361da177e4SLinus Torvalds 2637d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 2638044c782cSValentin Ilie pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" 2639d75f773cSSakari Ailus " last function: %ps\n", 2640a2c1c57bSTejun Heo current->comm, preempt_count(), task_pid_nr(current), 2641a2c1c57bSTejun Heo worker->current_func); 2642d5abe669SPeter Zijlstra debug_show_held_locks(current); 2643d5abe669SPeter Zijlstra dump_stack(); 2644d5abe669SPeter Zijlstra } 2645d5abe669SPeter Zijlstra 2646b22ce278STejun Heo /* 2647025f50f3SSebastian Andrzej Siewior * The following prevents a kworker from hogging CPU on !PREEMPTION 2648b22ce278STejun Heo * kernels, where a requeueing work item waiting for something to 2649b22ce278STejun Heo * happen could deadlock with stop_machine as such work item could 2650b22ce278STejun Heo * indefinitely requeue itself while all other CPUs are trapped in 2651789cbbecSJoe Lawrence * stop_machine. At the same time, report a quiescent RCU state so 2652789cbbecSJoe Lawrence * the same condition doesn't freeze RCU. 2653b22ce278STejun Heo */ 2654a7e6425eSPaul E. McKenney cond_resched(); 2655b22ce278STejun Heo 2656a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2657a62428c0STejun Heo 2658616db877STejun Heo /* 2659616db877STejun Heo * In addition to %WQ_CPU_INTENSIVE, @worker may also have been marked 2660616db877STejun Heo * CPU intensive by wq_worker_tick() if @work hogged CPU longer than 2661616db877STejun Heo * wq_cpu_intensive_thresh_us. Clear it. 2662616db877STejun Heo */ 2663fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 2664fb0e7bebSTejun Heo 26651b69ac6bSJohannes Weiner /* tag the worker for identification in schedule() */ 26661b69ac6bSJohannes Weiner worker->last_func = worker->current_func; 26671b69ac6bSJohannes Weiner 2668a62428c0STejun Heo /* we're done with it, release */ 266942f8570fSSasha Levin hash_del(&worker->hentry); 2670c34056a3STejun Heo worker->current_work = NULL; 2671a2c1c57bSTejun Heo worker->current_func = NULL; 2672112202d9STejun Heo worker->current_pwq = NULL; 2673d812796eSLai Jiangshan worker->current_color = INT_MAX; 2674c4560c2cSLai Jiangshan pwq_dec_nr_in_flight(pwq, work_data); 26751da177e4SLinus Torvalds } 26761da177e4SLinus Torvalds 2677affee4b2STejun Heo /** 2678affee4b2STejun Heo * process_scheduled_works - process scheduled works 2679affee4b2STejun Heo * @worker: self 2680affee4b2STejun Heo * 2681affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 2682affee4b2STejun Heo * may change while processing a work, so this function repeatedly 2683affee4b2STejun Heo * fetches a work from the top and executes it. 2684affee4b2STejun Heo * 2685affee4b2STejun Heo * CONTEXT: 2686a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 2687affee4b2STejun Heo * multiple times. 2688affee4b2STejun Heo */ 2689affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 26901da177e4SLinus Torvalds { 2691c0ab017dSTejun Heo struct work_struct *work; 2692c0ab017dSTejun Heo bool first = true; 2693c0ab017dSTejun Heo 2694c0ab017dSTejun Heo while ((work = list_first_entry_or_null(&worker->scheduled, 2695c0ab017dSTejun Heo struct work_struct, entry))) { 2696c0ab017dSTejun Heo if (first) { 2697c0ab017dSTejun Heo worker->pool->watchdog_ts = jiffies; 2698c0ab017dSTejun Heo first = false; 2699c0ab017dSTejun Heo } 2700c34056a3STejun Heo process_one_work(worker, work); 2701a62428c0STejun Heo } 27021da177e4SLinus Torvalds } 27031da177e4SLinus Torvalds 2704197f6accSTejun Heo static void set_pf_worker(bool val) 2705197f6accSTejun Heo { 2706197f6accSTejun Heo mutex_lock(&wq_pool_attach_mutex); 2707197f6accSTejun Heo if (val) 2708197f6accSTejun Heo current->flags |= PF_WQ_WORKER; 2709197f6accSTejun Heo else 2710197f6accSTejun Heo current->flags &= ~PF_WQ_WORKER; 2711197f6accSTejun Heo mutex_unlock(&wq_pool_attach_mutex); 2712197f6accSTejun Heo } 2713197f6accSTejun Heo 27144690c4abSTejun Heo /** 27154690c4abSTejun Heo * worker_thread - the worker thread function 2716c34056a3STejun Heo * @__worker: self 27174690c4abSTejun Heo * 2718c5aa87bbSTejun Heo * The worker thread function. All workers belong to a worker_pool - 2719c5aa87bbSTejun Heo * either a per-cpu one or dynamic unbound one. These workers process all 2720c5aa87bbSTejun Heo * work items regardless of their specific target workqueue. The only 2721c5aa87bbSTejun Heo * exception is work items which belong to workqueues with a rescuer which 2722c5aa87bbSTejun Heo * will be explained in rescuer_thread(). 2723d185af30SYacine Belkadi * 2724d185af30SYacine Belkadi * Return: 0 27254690c4abSTejun Heo */ 2726c34056a3STejun Heo static int worker_thread(void *__worker) 27271da177e4SLinus Torvalds { 2728c34056a3STejun Heo struct worker *worker = __worker; 2729bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 27301da177e4SLinus Torvalds 2731e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 2732197f6accSTejun Heo set_pf_worker(true); 2733c8e55f36STejun Heo woke_up: 2734a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2735affee4b2STejun Heo 2736a9ab775bSTejun Heo /* am I supposed to die? */ 2737a9ab775bSTejun Heo if (unlikely(worker->flags & WORKER_DIE)) { 2738a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2739197f6accSTejun Heo set_pf_worker(false); 274060f5a4bcSLai Jiangshan 274160f5a4bcSLai Jiangshan set_task_comm(worker->task, "kworker/dying"); 2742e441b56fSZhen Lei ida_free(&pool->worker_ida, worker->id); 2743a2d812a2STejun Heo worker_detach_from_pool(worker); 2744e02b9312SValentin Schneider WARN_ON_ONCE(!list_empty(&worker->entry)); 274560f5a4bcSLai Jiangshan kfree(worker); 2746c8e55f36STejun Heo return 0; 2747c8e55f36STejun Heo } 2748c8e55f36STejun Heo 2749c8e55f36STejun Heo worker_leave_idle(worker); 2750db7bccf4STejun Heo recheck: 2751e22bee78STejun Heo /* no more worker necessary? */ 275263d95a91STejun Heo if (!need_more_worker(pool)) 2753e22bee78STejun Heo goto sleep; 2754e22bee78STejun Heo 2755e22bee78STejun Heo /* do we need to manage? */ 275663d95a91STejun Heo if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 2757e22bee78STejun Heo goto recheck; 2758e22bee78STejun Heo 2759c8e55f36STejun Heo /* 2760c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 2761c8e55f36STejun Heo * preparing to process a work or actually processing it. 2762c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 2763c8e55f36STejun Heo */ 27646183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->scheduled)); 2765c8e55f36STejun Heo 2766e22bee78STejun Heo /* 2767a9ab775bSTejun Heo * Finish PREP stage. We're guaranteed to have at least one idle 2768a9ab775bSTejun Heo * worker or that someone else has already assumed the manager 2769a9ab775bSTejun Heo * role. This is where @worker starts participating in concurrency 2770a9ab775bSTejun Heo * management if applicable and concurrency management is restored 2771a9ab775bSTejun Heo * after being rebound. See rebind_workers() for details. 2772e22bee78STejun Heo */ 2773a9ab775bSTejun Heo worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); 2774e22bee78STejun Heo 2775e22bee78STejun Heo do { 2776affee4b2STejun Heo struct work_struct *work = 2777bd7bdd43STejun Heo list_first_entry(&pool->worklist, 2778affee4b2STejun Heo struct work_struct, entry); 2779affee4b2STejun Heo 2780873eaca6STejun Heo if (assign_work(work, worker, NULL)) 2781affee4b2STejun Heo process_scheduled_works(worker); 278263d95a91STejun Heo } while (keep_working(pool)); 2783affee4b2STejun Heo 2784228f1d00SLai Jiangshan worker_set_flags(worker, WORKER_PREP); 2785d313dd85STejun Heo sleep: 2786c8e55f36STejun Heo /* 2787d565ed63STejun Heo * pool->lock is held and there's no work to process and no need to 2788d565ed63STejun Heo * manage, sleep. Workers are woken up only while holding 2789d565ed63STejun Heo * pool->lock or from local cpu, so setting the current state 2790d565ed63STejun Heo * before releasing pool->lock is enough to prevent losing any 2791d565ed63STejun Heo * event. 2792c8e55f36STejun Heo */ 2793c8e55f36STejun Heo worker_enter_idle(worker); 2794c5a94a61SPeter Zijlstra __set_current_state(TASK_IDLE); 2795a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 27961da177e4SLinus Torvalds schedule(); 2797c8e55f36STejun Heo goto woke_up; 27981da177e4SLinus Torvalds } 27991da177e4SLinus Torvalds 2800e22bee78STejun Heo /** 2801e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2802111c225aSTejun Heo * @__rescuer: self 2803e22bee78STejun Heo * 2804e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2805493008a8STejun Heo * workqueue which has WQ_MEM_RECLAIM set. 2806e22bee78STejun Heo * 2807706026c2STejun Heo * Regular work processing on a pool may block trying to create a new 2808e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2809e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2810e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2811e22bee78STejun Heo * the problem rescuer solves. 2812e22bee78STejun Heo * 2813706026c2STejun Heo * When such condition is possible, the pool summons rescuers of all 2814706026c2STejun Heo * workqueues which have works queued on the pool and let them process 2815e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2816e22bee78STejun Heo * 2817e22bee78STejun Heo * This should happen rarely. 2818d185af30SYacine Belkadi * 2819d185af30SYacine Belkadi * Return: 0 2820e22bee78STejun Heo */ 2821111c225aSTejun Heo static int rescuer_thread(void *__rescuer) 2822e22bee78STejun Heo { 2823111c225aSTejun Heo struct worker *rescuer = __rescuer; 2824111c225aSTejun Heo struct workqueue_struct *wq = rescuer->rescue_wq; 28254d595b86SLai Jiangshan bool should_stop; 2826e22bee78STejun Heo 2827e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2828111c225aSTejun Heo 2829111c225aSTejun Heo /* 2830111c225aSTejun Heo * Mark rescuer as worker too. As WORKER_PREP is never cleared, it 2831111c225aSTejun Heo * doesn't participate in concurrency management. 2832111c225aSTejun Heo */ 2833197f6accSTejun Heo set_pf_worker(true); 2834e22bee78STejun Heo repeat: 2835c5a94a61SPeter Zijlstra set_current_state(TASK_IDLE); 28361da177e4SLinus Torvalds 28374d595b86SLai Jiangshan /* 28384d595b86SLai Jiangshan * By the time the rescuer is requested to stop, the workqueue 28394d595b86SLai Jiangshan * shouldn't have any work pending, but @wq->maydays may still have 28404d595b86SLai Jiangshan * pwq(s) queued. This can happen by non-rescuer workers consuming 28414d595b86SLai Jiangshan * all the work items before the rescuer got to them. Go through 28424d595b86SLai Jiangshan * @wq->maydays processing before acting on should_stop so that the 28434d595b86SLai Jiangshan * list is always empty on exit. 28444d595b86SLai Jiangshan */ 28454d595b86SLai Jiangshan should_stop = kthread_should_stop(); 28461da177e4SLinus Torvalds 2847493a1724STejun Heo /* see whether any pwq is asking for help */ 2848a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&wq_mayday_lock); 2849493a1724STejun Heo 2850493a1724STejun Heo while (!list_empty(&wq->maydays)) { 2851493a1724STejun Heo struct pool_workqueue *pwq = list_first_entry(&wq->maydays, 2852493a1724STejun Heo struct pool_workqueue, mayday_node); 2853112202d9STejun Heo struct worker_pool *pool = pwq->pool; 2854e22bee78STejun Heo struct work_struct *work, *n; 2855e22bee78STejun Heo 2856e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2857493a1724STejun Heo list_del_init(&pwq->mayday_node); 2858493a1724STejun Heo 2859a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&wq_mayday_lock); 2860e22bee78STejun Heo 286151697d39SLai Jiangshan worker_attach_to_pool(rescuer, pool); 286251697d39SLai Jiangshan 2863a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2864e22bee78STejun Heo 2865e22bee78STejun Heo /* 2866e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2867e22bee78STejun Heo * process'em. 2868e22bee78STejun Heo */ 2869873eaca6STejun Heo WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); 287082607adcSTejun Heo list_for_each_entry_safe(work, n, &pool->worklist, entry) { 2871873eaca6STejun Heo if (get_work_pwq(work) == pwq && 2872873eaca6STejun Heo assign_work(work, rescuer, &n)) 2873725e8ec5STejun Heo pwq->stats[PWQ_STAT_RESCUED]++; 287482607adcSTejun Heo } 2875e22bee78STejun Heo 2876873eaca6STejun Heo if (!list_empty(&rescuer->scheduled)) { 2877e22bee78STejun Heo process_scheduled_works(rescuer); 28787576958aSTejun Heo 28797576958aSTejun Heo /* 2880008847f6SNeilBrown * The above execution of rescued work items could 2881008847f6SNeilBrown * have created more to rescue through 2882f97a4a1aSLai Jiangshan * pwq_activate_first_inactive() or chained 2883008847f6SNeilBrown * queueing. Let's put @pwq back on mayday list so 2884008847f6SNeilBrown * that such back-to-back work items, which may be 2885008847f6SNeilBrown * being used to relieve memory pressure, don't 2886008847f6SNeilBrown * incur MAYDAY_INTERVAL delay inbetween. 2887008847f6SNeilBrown */ 28884f3f4cf3SLai Jiangshan if (pwq->nr_active && need_to_create_worker(pool)) { 2889a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&wq_mayday_lock); 2890e66b39afSTejun Heo /* 2891e66b39afSTejun Heo * Queue iff we aren't racing destruction 2892e66b39afSTejun Heo * and somebody else hasn't queued it already. 2893e66b39afSTejun Heo */ 2894e66b39afSTejun Heo if (wq->rescuer && list_empty(&pwq->mayday_node)) { 2895008847f6SNeilBrown get_pwq(pwq); 2896e66b39afSTejun Heo list_add_tail(&pwq->mayday_node, &wq->maydays); 2897e66b39afSTejun Heo } 2898a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&wq_mayday_lock); 2899008847f6SNeilBrown } 2900008847f6SNeilBrown } 2901008847f6SNeilBrown 2902008847f6SNeilBrown /* 290377668c8bSLai Jiangshan * Put the reference grabbed by send_mayday(). @pool won't 290413b1d625SLai Jiangshan * go away while we're still attached to it. 290577668c8bSLai Jiangshan */ 290677668c8bSLai Jiangshan put_pwq(pwq); 290777668c8bSLai Jiangshan 290877668c8bSLai Jiangshan /* 29090219a352STejun Heo * Leave this pool. Notify regular workers; otherwise, we end up 29100219a352STejun Heo * with 0 concurrency and stalling the execution. 29117576958aSTejun Heo */ 29120219a352STejun Heo kick_pool(pool); 29137576958aSTejun Heo 2914a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 291513b1d625SLai Jiangshan 2916a2d812a2STejun Heo worker_detach_from_pool(rescuer); 291713b1d625SLai Jiangshan 2918a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&wq_mayday_lock); 29191da177e4SLinus Torvalds } 29201da177e4SLinus Torvalds 2921a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&wq_mayday_lock); 2922493a1724STejun Heo 29234d595b86SLai Jiangshan if (should_stop) { 29244d595b86SLai Jiangshan __set_current_state(TASK_RUNNING); 2925197f6accSTejun Heo set_pf_worker(false); 29264d595b86SLai Jiangshan return 0; 29274d595b86SLai Jiangshan } 29284d595b86SLai Jiangshan 2929111c225aSTejun Heo /* rescuers should never participate in concurrency management */ 2930111c225aSTejun Heo WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); 2931e22bee78STejun Heo schedule(); 2932e22bee78STejun Heo goto repeat; 29331da177e4SLinus Torvalds } 29341da177e4SLinus Torvalds 2935fca839c0STejun Heo /** 2936fca839c0STejun Heo * check_flush_dependency - check for flush dependency sanity 2937fca839c0STejun Heo * @target_wq: workqueue being flushed 2938fca839c0STejun Heo * @target_work: work item being flushed (NULL for workqueue flushes) 2939fca839c0STejun Heo * 2940fca839c0STejun Heo * %current is trying to flush the whole @target_wq or @target_work on it. 2941fca839c0STejun Heo * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not 2942fca839c0STejun Heo * reclaiming memory or running on a workqueue which doesn't have 2943fca839c0STejun Heo * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to 2944fca839c0STejun Heo * a deadlock. 2945fca839c0STejun Heo */ 2946fca839c0STejun Heo static void check_flush_dependency(struct workqueue_struct *target_wq, 2947fca839c0STejun Heo struct work_struct *target_work) 2948fca839c0STejun Heo { 2949fca839c0STejun Heo work_func_t target_func = target_work ? target_work->func : NULL; 2950fca839c0STejun Heo struct worker *worker; 2951fca839c0STejun Heo 2952fca839c0STejun Heo if (target_wq->flags & WQ_MEM_RECLAIM) 2953fca839c0STejun Heo return; 2954fca839c0STejun Heo 2955fca839c0STejun Heo worker = current_wq_worker(); 2956fca839c0STejun Heo 2957fca839c0STejun Heo WARN_ONCE(current->flags & PF_MEMALLOC, 2958d75f773cSSakari Ailus "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", 2959fca839c0STejun Heo current->pid, current->comm, target_wq->name, target_func); 296023d11a58STejun Heo WARN_ONCE(worker && ((worker->current_pwq->wq->flags & 296123d11a58STejun Heo (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), 2962d75f773cSSakari Ailus "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps", 2963fca839c0STejun Heo worker->current_pwq->wq->name, worker->current_func, 2964fca839c0STejun Heo target_wq->name, target_func); 2965fca839c0STejun Heo } 2966fca839c0STejun Heo 2967fc2e4d70SOleg Nesterov struct wq_barrier { 2968fc2e4d70SOleg Nesterov struct work_struct work; 2969fc2e4d70SOleg Nesterov struct completion done; 29702607d7a6STejun Heo struct task_struct *task; /* purely informational */ 2971fc2e4d70SOleg Nesterov }; 2972fc2e4d70SOleg Nesterov 2973fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2974fc2e4d70SOleg Nesterov { 2975fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2976fc2e4d70SOleg Nesterov complete(&barr->done); 2977fc2e4d70SOleg Nesterov } 2978fc2e4d70SOleg Nesterov 29794690c4abSTejun Heo /** 29804690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 2981112202d9STejun Heo * @pwq: pwq to insert barrier into 29824690c4abSTejun Heo * @barr: wq_barrier to insert 2983affee4b2STejun Heo * @target: target work to attach @barr to 2984affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 29854690c4abSTejun Heo * 2986affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2987affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2988affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2989affee4b2STejun Heo * cpu. 2990affee4b2STejun Heo * 2991affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2992affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2993affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2994affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2995affee4b2STejun Heo * after a work with LINKED flag set. 2996affee4b2STejun Heo * 2997affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2998112202d9STejun Heo * underneath us, so we can't reliably determine pwq from @target. 29994690c4abSTejun Heo * 30004690c4abSTejun Heo * CONTEXT: 3001a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 30024690c4abSTejun Heo */ 3003112202d9STejun Heo static void insert_wq_barrier(struct pool_workqueue *pwq, 3004affee4b2STejun Heo struct wq_barrier *barr, 3005affee4b2STejun Heo struct work_struct *target, struct worker *worker) 3006fc2e4d70SOleg Nesterov { 3007d812796eSLai Jiangshan unsigned int work_flags = 0; 3008d812796eSLai Jiangshan unsigned int work_color; 3009affee4b2STejun Heo struct list_head *head; 3010affee4b2STejun Heo 3011dc186ad7SThomas Gleixner /* 3012d565ed63STejun Heo * debugobject calls are safe here even with pool->lock locked 3013dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 3014dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 3015dc186ad7SThomas Gleixner * might deadlock. 3016dc186ad7SThomas Gleixner */ 3017ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 301822df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 301952fa5bc5SBoqun Feng 3020fd1a5b04SByungchul Park init_completion_map(&barr->done, &target->lockdep_map); 3021fd1a5b04SByungchul Park 30222607d7a6STejun Heo barr->task = current; 302383c22520SOleg Nesterov 3024018f3a13SLai Jiangshan /* The barrier work item does not participate in pwq->nr_active. */ 3025018f3a13SLai Jiangshan work_flags |= WORK_STRUCT_INACTIVE; 3026018f3a13SLai Jiangshan 3027affee4b2STejun Heo /* 3028affee4b2STejun Heo * If @target is currently being executed, schedule the 3029affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 3030affee4b2STejun Heo */ 3031d812796eSLai Jiangshan if (worker) { 3032affee4b2STejun Heo head = worker->scheduled.next; 3033d812796eSLai Jiangshan work_color = worker->current_color; 3034d812796eSLai Jiangshan } else { 3035affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 3036affee4b2STejun Heo 3037affee4b2STejun Heo head = target->entry.next; 3038affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 3039d21cece0SLai Jiangshan work_flags |= *bits & WORK_STRUCT_LINKED; 3040d812796eSLai Jiangshan work_color = get_work_color(*bits); 3041affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 3042affee4b2STejun Heo } 3043affee4b2STejun Heo 3044d812796eSLai Jiangshan pwq->nr_in_flight[work_color]++; 3045d812796eSLai Jiangshan work_flags |= work_color_to_flags(work_color); 3046d812796eSLai Jiangshan 3047d21cece0SLai Jiangshan insert_work(pwq, &barr->work, head, work_flags); 3048fc2e4d70SOleg Nesterov } 3049fc2e4d70SOleg Nesterov 305073f53c4aSTejun Heo /** 3051112202d9STejun Heo * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing 305273f53c4aSTejun Heo * @wq: workqueue being flushed 305373f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 305473f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 305573f53c4aSTejun Heo * 3056112202d9STejun Heo * Prepare pwqs for workqueue flushing. 305773f53c4aSTejun Heo * 3058112202d9STejun Heo * If @flush_color is non-negative, flush_color on all pwqs should be 3059112202d9STejun Heo * -1. If no pwq has in-flight commands at the specified color, all 3060112202d9STejun Heo * pwq->flush_color's stay at -1 and %false is returned. If any pwq 3061112202d9STejun Heo * has in flight commands, its pwq->flush_color is set to 3062112202d9STejun Heo * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq 306373f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 306473f53c4aSTejun Heo * 306573f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 306673f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 306773f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 306873f53c4aSTejun Heo * is returned. 306973f53c4aSTejun Heo * 3070112202d9STejun Heo * If @work_color is non-negative, all pwqs should have the same 307173f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 307273f53c4aSTejun Heo * advanced to @work_color. 307373f53c4aSTejun Heo * 307473f53c4aSTejun Heo * CONTEXT: 30753c25a55dSLai Jiangshan * mutex_lock(wq->mutex). 307673f53c4aSTejun Heo * 3077d185af30SYacine Belkadi * Return: 307873f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 307973f53c4aSTejun Heo * otherwise. 308073f53c4aSTejun Heo */ 3081112202d9STejun Heo static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, 308273f53c4aSTejun Heo int flush_color, int work_color) 30831da177e4SLinus Torvalds { 308473f53c4aSTejun Heo bool wait = false; 308549e3cf44STejun Heo struct pool_workqueue *pwq; 30861da177e4SLinus Torvalds 308773f53c4aSTejun Heo if (flush_color >= 0) { 30886183c009STejun Heo WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); 3089112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 1); 3090dc186ad7SThomas Gleixner } 309114441960SOleg Nesterov 309249e3cf44STejun Heo for_each_pwq(pwq, wq) { 3093112202d9STejun Heo struct worker_pool *pool = pwq->pool; 30941da177e4SLinus Torvalds 3095a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 309673f53c4aSTejun Heo 309773f53c4aSTejun Heo if (flush_color >= 0) { 30986183c009STejun Heo WARN_ON_ONCE(pwq->flush_color != -1); 309973f53c4aSTejun Heo 3100112202d9STejun Heo if (pwq->nr_in_flight[flush_color]) { 3101112202d9STejun Heo pwq->flush_color = flush_color; 3102112202d9STejun Heo atomic_inc(&wq->nr_pwqs_to_flush); 310373f53c4aSTejun Heo wait = true; 31041da177e4SLinus Torvalds } 310573f53c4aSTejun Heo } 310673f53c4aSTejun Heo 310773f53c4aSTejun Heo if (work_color >= 0) { 31086183c009STejun Heo WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); 3109112202d9STejun Heo pwq->work_color = work_color; 311073f53c4aSTejun Heo } 311173f53c4aSTejun Heo 3112a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 31131da177e4SLinus Torvalds } 31141da177e4SLinus Torvalds 3115112202d9STejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) 311673f53c4aSTejun Heo complete(&wq->first_flusher->done); 311773f53c4aSTejun Heo 311873f53c4aSTejun Heo return wait; 311983c22520SOleg Nesterov } 31201da177e4SLinus Torvalds 31210fcb78c2SRolf Eike Beer /** 3122c4f135d6STetsuo Handa * __flush_workqueue - ensure that any scheduled work has run to completion. 31230fcb78c2SRolf Eike Beer * @wq: workqueue to flush 31241da177e4SLinus Torvalds * 3125c5aa87bbSTejun Heo * This function sleeps until all work items which were queued on entry 3126c5aa87bbSTejun Heo * have finished execution, but it is not livelocked by new incoming ones. 31271da177e4SLinus Torvalds */ 3128c4f135d6STetsuo Handa void __flush_workqueue(struct workqueue_struct *wq) 31291da177e4SLinus Torvalds { 313073f53c4aSTejun Heo struct wq_flusher this_flusher = { 313173f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 313273f53c4aSTejun Heo .flush_color = -1, 3133fd1a5b04SByungchul Park .done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map), 313473f53c4aSTejun Heo }; 313573f53c4aSTejun Heo int next_color; 3136b1f4ec17SOleg Nesterov 31373347fa09STejun Heo if (WARN_ON(!wq_online)) 31383347fa09STejun Heo return; 31393347fa09STejun Heo 314087915adcSJohannes Berg lock_map_acquire(&wq->lockdep_map); 314187915adcSJohannes Berg lock_map_release(&wq->lockdep_map); 314287915adcSJohannes Berg 31433c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 314473f53c4aSTejun Heo 314573f53c4aSTejun Heo /* 314673f53c4aSTejun Heo * Start-to-wait phase 314773f53c4aSTejun Heo */ 314873f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 314973f53c4aSTejun Heo 315073f53c4aSTejun Heo if (next_color != wq->flush_color) { 315173f53c4aSTejun Heo /* 315273f53c4aSTejun Heo * Color space is not full. The current work_color 315373f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 315473f53c4aSTejun Heo * by one. 315573f53c4aSTejun Heo */ 31566183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); 315773f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 315873f53c4aSTejun Heo wq->work_color = next_color; 315973f53c4aSTejun Heo 316073f53c4aSTejun Heo if (!wq->first_flusher) { 316173f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 31626183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 316373f53c4aSTejun Heo 316473f53c4aSTejun Heo wq->first_flusher = &this_flusher; 316573f53c4aSTejun Heo 3166112202d9STejun Heo if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, 316773f53c4aSTejun Heo wq->work_color)) { 316873f53c4aSTejun Heo /* nothing to flush, done */ 316973f53c4aSTejun Heo wq->flush_color = next_color; 317073f53c4aSTejun Heo wq->first_flusher = NULL; 317173f53c4aSTejun Heo goto out_unlock; 317273f53c4aSTejun Heo } 317373f53c4aSTejun Heo } else { 317473f53c4aSTejun Heo /* wait in queue */ 31756183c009STejun Heo WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); 317673f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 3177112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 317873f53c4aSTejun Heo } 317973f53c4aSTejun Heo } else { 318073f53c4aSTejun Heo /* 318173f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 318273f53c4aSTejun Heo * The next flush completion will assign us 318373f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 318473f53c4aSTejun Heo */ 318573f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 318673f53c4aSTejun Heo } 318773f53c4aSTejun Heo 3188fca839c0STejun Heo check_flush_dependency(wq, NULL); 3189fca839c0STejun Heo 31903c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 319173f53c4aSTejun Heo 319273f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 319373f53c4aSTejun Heo 319473f53c4aSTejun Heo /* 319573f53c4aSTejun Heo * Wake-up-and-cascade phase 319673f53c4aSTejun Heo * 319773f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 319873f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 319973f53c4aSTejun Heo */ 320000d5d15bSChris Wilson if (READ_ONCE(wq->first_flusher) != &this_flusher) 320173f53c4aSTejun Heo return; 320273f53c4aSTejun Heo 32033c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 320473f53c4aSTejun Heo 32054ce48b37STejun Heo /* we might have raced, check again with mutex held */ 32064ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 32074ce48b37STejun Heo goto out_unlock; 32084ce48b37STejun Heo 320900d5d15bSChris Wilson WRITE_ONCE(wq->first_flusher, NULL); 321073f53c4aSTejun Heo 32116183c009STejun Heo WARN_ON_ONCE(!list_empty(&this_flusher.list)); 32126183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 321373f53c4aSTejun Heo 321473f53c4aSTejun Heo while (true) { 321573f53c4aSTejun Heo struct wq_flusher *next, *tmp; 321673f53c4aSTejun Heo 321773f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 321873f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 321973f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 322073f53c4aSTejun Heo break; 322173f53c4aSTejun Heo list_del_init(&next->list); 322273f53c4aSTejun Heo complete(&next->done); 322373f53c4aSTejun Heo } 322473f53c4aSTejun Heo 32256183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && 322673f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 322773f53c4aSTejun Heo 322873f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 322973f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 323073f53c4aSTejun Heo 323173f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 323273f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 323373f53c4aSTejun Heo /* 323473f53c4aSTejun Heo * Assign the same color to all overflowed 323573f53c4aSTejun Heo * flushers, advance work_color and append to 323673f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 323773f53c4aSTejun Heo * phase for these overflowed flushers. 323873f53c4aSTejun Heo */ 323973f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 324073f53c4aSTejun Heo tmp->flush_color = wq->work_color; 324173f53c4aSTejun Heo 324273f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 324373f53c4aSTejun Heo 324473f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 324573f53c4aSTejun Heo &wq->flusher_queue); 3246112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 324773f53c4aSTejun Heo } 324873f53c4aSTejun Heo 324973f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 32506183c009STejun Heo WARN_ON_ONCE(wq->flush_color != wq->work_color); 325173f53c4aSTejun Heo break; 325273f53c4aSTejun Heo } 325373f53c4aSTejun Heo 325473f53c4aSTejun Heo /* 325573f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 3256112202d9STejun Heo * the new first flusher and arm pwqs. 325773f53c4aSTejun Heo */ 32586183c009STejun Heo WARN_ON_ONCE(wq->flush_color == wq->work_color); 32596183c009STejun Heo WARN_ON_ONCE(wq->flush_color != next->flush_color); 326073f53c4aSTejun Heo 326173f53c4aSTejun Heo list_del_init(&next->list); 326273f53c4aSTejun Heo wq->first_flusher = next; 326373f53c4aSTejun Heo 3264112202d9STejun Heo if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) 326573f53c4aSTejun Heo break; 326673f53c4aSTejun Heo 326773f53c4aSTejun Heo /* 326873f53c4aSTejun Heo * Meh... this color is already done, clear first 326973f53c4aSTejun Heo * flusher and repeat cascading. 327073f53c4aSTejun Heo */ 327173f53c4aSTejun Heo wq->first_flusher = NULL; 327273f53c4aSTejun Heo } 327373f53c4aSTejun Heo 327473f53c4aSTejun Heo out_unlock: 32753c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 32761da177e4SLinus Torvalds } 3277c4f135d6STetsuo Handa EXPORT_SYMBOL(__flush_workqueue); 32781da177e4SLinus Torvalds 32799c5a2ba7STejun Heo /** 32809c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 32819c5a2ba7STejun Heo * @wq: workqueue to drain 32829c5a2ba7STejun Heo * 32839c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 32849c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 32859c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 3286b749b1b6SChen Hanxiao * repeatedly until it becomes empty. The number of flushing is determined 32879c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 32889c5a2ba7STejun Heo * takes too long. 32899c5a2ba7STejun Heo */ 32909c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 32919c5a2ba7STejun Heo { 32929c5a2ba7STejun Heo unsigned int flush_cnt = 0; 329349e3cf44STejun Heo struct pool_workqueue *pwq; 32949c5a2ba7STejun Heo 32959c5a2ba7STejun Heo /* 32969c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 32979c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 3298618b01ebSTejun Heo * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. 32999c5a2ba7STejun Heo */ 330087fc741eSLai Jiangshan mutex_lock(&wq->mutex); 33019c5a2ba7STejun Heo if (!wq->nr_drainers++) 3302618b01ebSTejun Heo wq->flags |= __WQ_DRAINING; 330387fc741eSLai Jiangshan mutex_unlock(&wq->mutex); 33049c5a2ba7STejun Heo reflush: 3305c4f135d6STetsuo Handa __flush_workqueue(wq); 33069c5a2ba7STejun Heo 3307b09f4fd3SLai Jiangshan mutex_lock(&wq->mutex); 330876af4d93STejun Heo 330949e3cf44STejun Heo for_each_pwq(pwq, wq) { 3310fa2563e4SThomas Tuttle bool drained; 33119c5a2ba7STejun Heo 3312a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pwq->pool->lock); 3313f97a4a1aSLai Jiangshan drained = !pwq->nr_active && list_empty(&pwq->inactive_works); 3314a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pwq->pool->lock); 3315fa2563e4SThomas Tuttle 3316fa2563e4SThomas Tuttle if (drained) 33179c5a2ba7STejun Heo continue; 33189c5a2ba7STejun Heo 33199c5a2ba7STejun Heo if (++flush_cnt == 10 || 33209c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 3321e9ad2eb3SStephen Zhang pr_warn("workqueue %s: %s() isn't complete after %u tries\n", 3322e9ad2eb3SStephen Zhang wq->name, __func__, flush_cnt); 332376af4d93STejun Heo 3324b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 33259c5a2ba7STejun Heo goto reflush; 33269c5a2ba7STejun Heo } 33279c5a2ba7STejun Heo 33289c5a2ba7STejun Heo if (!--wq->nr_drainers) 3329618b01ebSTejun Heo wq->flags &= ~__WQ_DRAINING; 333087fc741eSLai Jiangshan mutex_unlock(&wq->mutex); 33319c5a2ba7STejun Heo } 33329c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 33339c5a2ba7STejun Heo 3334d6e89786SJohannes Berg static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, 3335d6e89786SJohannes Berg bool from_cancel) 3336baf59022STejun Heo { 3337baf59022STejun Heo struct worker *worker = NULL; 3338c9e7cf27STejun Heo struct worker_pool *pool; 3339112202d9STejun Heo struct pool_workqueue *pwq; 3340baf59022STejun Heo 3341baf59022STejun Heo might_sleep(); 3342baf59022STejun Heo 334324acfb71SThomas Gleixner rcu_read_lock(); 3344fa1b54e6STejun Heo pool = get_work_pool(work); 3345fa1b54e6STejun Heo if (!pool) { 334624acfb71SThomas Gleixner rcu_read_unlock(); 3347fa1b54e6STejun Heo return false; 3348fa1b54e6STejun Heo } 3349fa1b54e6STejun Heo 3350a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 33510b3dae68SLai Jiangshan /* see the comment in try_to_grab_pending() with the same code */ 3352112202d9STejun Heo pwq = get_work_pwq(work); 3353112202d9STejun Heo if (pwq) { 3354112202d9STejun Heo if (unlikely(pwq->pool != pool)) 3355baf59022STejun Heo goto already_gone; 3356606a5020STejun Heo } else { 3357c9e7cf27STejun Heo worker = find_worker_executing_work(pool, work); 3358baf59022STejun Heo if (!worker) 3359baf59022STejun Heo goto already_gone; 3360112202d9STejun Heo pwq = worker->current_pwq; 3361606a5020STejun Heo } 3362baf59022STejun Heo 3363fca839c0STejun Heo check_flush_dependency(pwq->wq, work); 3364fca839c0STejun Heo 3365112202d9STejun Heo insert_wq_barrier(pwq, barr, work, worker); 3366a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 3367baf59022STejun Heo 3368e159489bSTejun Heo /* 3369a1d14934SPeter Zijlstra * Force a lock recursion deadlock when using flush_work() inside a 3370a1d14934SPeter Zijlstra * single-threaded or rescuer equipped workqueue. 3371a1d14934SPeter Zijlstra * 3372a1d14934SPeter Zijlstra * For single threaded workqueues the deadlock happens when the work 3373a1d14934SPeter Zijlstra * is after the work issuing the flush_work(). For rescuer equipped 3374a1d14934SPeter Zijlstra * workqueues the deadlock happens when the rescuer stalls, blocking 3375a1d14934SPeter Zijlstra * forward progress. 3376e159489bSTejun Heo */ 3377d6e89786SJohannes Berg if (!from_cancel && 3378d6e89786SJohannes Berg (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)) { 3379112202d9STejun Heo lock_map_acquire(&pwq->wq->lockdep_map); 3380112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 3381a1d14934SPeter Zijlstra } 338224acfb71SThomas Gleixner rcu_read_unlock(); 3383baf59022STejun Heo return true; 3384baf59022STejun Heo already_gone: 3385a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 338624acfb71SThomas Gleixner rcu_read_unlock(); 3387baf59022STejun Heo return false; 3388baf59022STejun Heo } 3389baf59022STejun Heo 3390d6e89786SJohannes Berg static bool __flush_work(struct work_struct *work, bool from_cancel) 3391d6e89786SJohannes Berg { 3392d6e89786SJohannes Berg struct wq_barrier barr; 3393d6e89786SJohannes Berg 3394d6e89786SJohannes Berg if (WARN_ON(!wq_online)) 3395d6e89786SJohannes Berg return false; 3396d6e89786SJohannes Berg 33974d43d395STetsuo Handa if (WARN_ON(!work->func)) 33984d43d395STetsuo Handa return false; 33994d43d395STetsuo Handa 340087915adcSJohannes Berg lock_map_acquire(&work->lockdep_map); 340187915adcSJohannes Berg lock_map_release(&work->lockdep_map); 340287915adcSJohannes Berg 3403d6e89786SJohannes Berg if (start_flush_work(work, &barr, from_cancel)) { 3404d6e89786SJohannes Berg wait_for_completion(&barr.done); 3405d6e89786SJohannes Berg destroy_work_on_stack(&barr.work); 3406d6e89786SJohannes Berg return true; 3407d6e89786SJohannes Berg } else { 3408d6e89786SJohannes Berg return false; 3409d6e89786SJohannes Berg } 3410d6e89786SJohannes Berg } 3411d6e89786SJohannes Berg 3412db700897SOleg Nesterov /** 3413401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 3414401a8d04STejun Heo * @work: the work to flush 3415db700897SOleg Nesterov * 3416606a5020STejun Heo * Wait until @work has finished execution. @work is guaranteed to be idle 3417606a5020STejun Heo * on return if it hasn't been requeued since flush started. 3418401a8d04STejun Heo * 3419d185af30SYacine Belkadi * Return: 3420401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 3421401a8d04STejun Heo * %false if it was already idle. 3422db700897SOleg Nesterov */ 3423401a8d04STejun Heo bool flush_work(struct work_struct *work) 3424db700897SOleg Nesterov { 3425d6e89786SJohannes Berg return __flush_work(work, false); 3426606a5020STejun Heo } 3427db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 3428db700897SOleg Nesterov 34298603e1b3STejun Heo struct cwt_wait { 3430ac6424b9SIngo Molnar wait_queue_entry_t wait; 34318603e1b3STejun Heo struct work_struct *work; 34328603e1b3STejun Heo }; 34338603e1b3STejun Heo 3434ac6424b9SIngo Molnar static int cwt_wakefn(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) 34358603e1b3STejun Heo { 34368603e1b3STejun Heo struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait); 34378603e1b3STejun Heo 34388603e1b3STejun Heo if (cwait->work != key) 34398603e1b3STejun Heo return 0; 34408603e1b3STejun Heo return autoremove_wake_function(wait, mode, sync, key); 34418603e1b3STejun Heo } 34428603e1b3STejun Heo 344336e227d2STejun Heo static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 3444401a8d04STejun Heo { 34458603e1b3STejun Heo static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq); 3446bbb68dfaSTejun Heo unsigned long flags; 34471f1f642eSOleg Nesterov int ret; 34481f1f642eSOleg Nesterov 34491f1f642eSOleg Nesterov do { 3450bbb68dfaSTejun Heo ret = try_to_grab_pending(work, is_dwork, &flags); 3451bbb68dfaSTejun Heo /* 34528603e1b3STejun Heo * If someone else is already canceling, wait for it to 34538603e1b3STejun Heo * finish. flush_work() doesn't work for PREEMPT_NONE 34548603e1b3STejun Heo * because we may get scheduled between @work's completion 34558603e1b3STejun Heo * and the other canceling task resuming and clearing 34568603e1b3STejun Heo * CANCELING - flush_work() will return false immediately 34578603e1b3STejun Heo * as @work is no longer busy, try_to_grab_pending() will 34588603e1b3STejun Heo * return -ENOENT as @work is still being canceled and the 34598603e1b3STejun Heo * other canceling task won't be able to clear CANCELING as 34608603e1b3STejun Heo * we're hogging the CPU. 34618603e1b3STejun Heo * 34628603e1b3STejun Heo * Let's wait for completion using a waitqueue. As this 34638603e1b3STejun Heo * may lead to the thundering herd problem, use a custom 34648603e1b3STejun Heo * wake function which matches @work along with exclusive 34658603e1b3STejun Heo * wait and wakeup. 3466bbb68dfaSTejun Heo */ 34678603e1b3STejun Heo if (unlikely(ret == -ENOENT)) { 34688603e1b3STejun Heo struct cwt_wait cwait; 34698603e1b3STejun Heo 34708603e1b3STejun Heo init_wait(&cwait.wait); 34718603e1b3STejun Heo cwait.wait.func = cwt_wakefn; 34728603e1b3STejun Heo cwait.work = work; 34738603e1b3STejun Heo 34748603e1b3STejun Heo prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait, 34758603e1b3STejun Heo TASK_UNINTERRUPTIBLE); 34768603e1b3STejun Heo if (work_is_canceling(work)) 34778603e1b3STejun Heo schedule(); 34788603e1b3STejun Heo finish_wait(&cancel_waitq, &cwait.wait); 34798603e1b3STejun Heo } 34801f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 34811f1f642eSOleg Nesterov 3482bbb68dfaSTejun Heo /* tell other tasks trying to grab @work to back off */ 3483bbb68dfaSTejun Heo mark_work_canceling(work); 3484bbb68dfaSTejun Heo local_irq_restore(flags); 3485bbb68dfaSTejun Heo 34863347fa09STejun Heo /* 34873347fa09STejun Heo * This allows canceling during early boot. We know that @work 34883347fa09STejun Heo * isn't executing. 34893347fa09STejun Heo */ 34903347fa09STejun Heo if (wq_online) 3491d6e89786SJohannes Berg __flush_work(work, true); 34923347fa09STejun Heo 34937a22ad75STejun Heo clear_work_data(work); 34948603e1b3STejun Heo 34958603e1b3STejun Heo /* 34968603e1b3STejun Heo * Paired with prepare_to_wait() above so that either 34978603e1b3STejun Heo * waitqueue_active() is visible here or !work_is_canceling() is 34988603e1b3STejun Heo * visible there. 34998603e1b3STejun Heo */ 35008603e1b3STejun Heo smp_mb(); 35018603e1b3STejun Heo if (waitqueue_active(&cancel_waitq)) 35028603e1b3STejun Heo __wake_up(&cancel_waitq, TASK_NORMAL, 1, work); 35038603e1b3STejun Heo 35041f1f642eSOleg Nesterov return ret; 35051f1f642eSOleg Nesterov } 35061f1f642eSOleg Nesterov 35076e84d644SOleg Nesterov /** 3508401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 3509401a8d04STejun Heo * @work: the work to cancel 35106e84d644SOleg Nesterov * 3511401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 3512401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 3513401a8d04STejun Heo * another workqueue. On return from this function, @work is 3514401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 35151f1f642eSOleg Nesterov * 3516401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 3517401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 35186e84d644SOleg Nesterov * 3519401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 35206e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 3521401a8d04STejun Heo * 3522d185af30SYacine Belkadi * Return: 3523401a8d04STejun Heo * %true if @work was pending, %false otherwise. 35246e84d644SOleg Nesterov */ 3525401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 35266e84d644SOleg Nesterov { 352736e227d2STejun Heo return __cancel_work_timer(work, false); 3528b89deed3SOleg Nesterov } 352928e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 3530b89deed3SOleg Nesterov 35316e84d644SOleg Nesterov /** 3532401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 3533401a8d04STejun Heo * @dwork: the delayed work to flush 35346e84d644SOleg Nesterov * 3535401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 3536401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 3537401a8d04STejun Heo * considers the last queueing instance of @dwork. 35381f1f642eSOleg Nesterov * 3539d185af30SYacine Belkadi * Return: 3540401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 3541401a8d04STejun Heo * %false if it was already idle. 35426e84d644SOleg Nesterov */ 3543401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 3544401a8d04STejun Heo { 35458930cabaSTejun Heo local_irq_disable(); 3546401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 354760c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 35488930cabaSTejun Heo local_irq_enable(); 3549401a8d04STejun Heo return flush_work(&dwork->work); 3550401a8d04STejun Heo } 3551401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 3552401a8d04STejun Heo 355305f0fe6bSTejun Heo /** 355405f0fe6bSTejun Heo * flush_rcu_work - wait for a rwork to finish executing the last queueing 355505f0fe6bSTejun Heo * @rwork: the rcu work to flush 355605f0fe6bSTejun Heo * 355705f0fe6bSTejun Heo * Return: 355805f0fe6bSTejun Heo * %true if flush_rcu_work() waited for the work to finish execution, 355905f0fe6bSTejun Heo * %false if it was already idle. 356005f0fe6bSTejun Heo */ 356105f0fe6bSTejun Heo bool flush_rcu_work(struct rcu_work *rwork) 356205f0fe6bSTejun Heo { 356305f0fe6bSTejun Heo if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) { 356405f0fe6bSTejun Heo rcu_barrier(); 356505f0fe6bSTejun Heo flush_work(&rwork->work); 356605f0fe6bSTejun Heo return true; 356705f0fe6bSTejun Heo } else { 356805f0fe6bSTejun Heo return flush_work(&rwork->work); 356905f0fe6bSTejun Heo } 357005f0fe6bSTejun Heo } 357105f0fe6bSTejun Heo EXPORT_SYMBOL(flush_rcu_work); 357205f0fe6bSTejun Heo 3573f72b8792SJens Axboe static bool __cancel_work(struct work_struct *work, bool is_dwork) 3574f72b8792SJens Axboe { 3575f72b8792SJens Axboe unsigned long flags; 3576f72b8792SJens Axboe int ret; 3577f72b8792SJens Axboe 3578f72b8792SJens Axboe do { 3579f72b8792SJens Axboe ret = try_to_grab_pending(work, is_dwork, &flags); 3580f72b8792SJens Axboe } while (unlikely(ret == -EAGAIN)); 3581f72b8792SJens Axboe 3582f72b8792SJens Axboe if (unlikely(ret < 0)) 3583f72b8792SJens Axboe return false; 3584f72b8792SJens Axboe 3585f72b8792SJens Axboe set_work_pool_and_clear_pending(work, get_work_pool_id(work)); 3586f72b8792SJens Axboe local_irq_restore(flags); 3587f72b8792SJens Axboe return ret; 3588f72b8792SJens Axboe } 3589f72b8792SJens Axboe 359073b4b532SAndrey Grodzovsky /* 359173b4b532SAndrey Grodzovsky * See cancel_delayed_work() 359273b4b532SAndrey Grodzovsky */ 359373b4b532SAndrey Grodzovsky bool cancel_work(struct work_struct *work) 359473b4b532SAndrey Grodzovsky { 359573b4b532SAndrey Grodzovsky return __cancel_work(work, false); 359673b4b532SAndrey Grodzovsky } 359773b4b532SAndrey Grodzovsky EXPORT_SYMBOL(cancel_work); 359873b4b532SAndrey Grodzovsky 3599401a8d04STejun Heo /** 360057b30ae7STejun Heo * cancel_delayed_work - cancel a delayed work 360157b30ae7STejun Heo * @dwork: delayed_work to cancel 360209383498STejun Heo * 3603d185af30SYacine Belkadi * Kill off a pending delayed_work. 3604d185af30SYacine Belkadi * 3605d185af30SYacine Belkadi * Return: %true if @dwork was pending and canceled; %false if it wasn't 3606d185af30SYacine Belkadi * pending. 3607d185af30SYacine Belkadi * 3608d185af30SYacine Belkadi * Note: 3609d185af30SYacine Belkadi * The work callback function may still be running on return, unless 3610d185af30SYacine Belkadi * it returns %true and the work doesn't re-arm itself. Explicitly flush or 3611d185af30SYacine Belkadi * use cancel_delayed_work_sync() to wait on it. 361209383498STejun Heo * 361357b30ae7STejun Heo * This function is safe to call from any context including IRQ handler. 361409383498STejun Heo */ 361557b30ae7STejun Heo bool cancel_delayed_work(struct delayed_work *dwork) 361609383498STejun Heo { 3617f72b8792SJens Axboe return __cancel_work(&dwork->work, true); 361809383498STejun Heo } 361957b30ae7STejun Heo EXPORT_SYMBOL(cancel_delayed_work); 362009383498STejun Heo 362109383498STejun Heo /** 3622401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 3623401a8d04STejun Heo * @dwork: the delayed work cancel 3624401a8d04STejun Heo * 3625401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 3626401a8d04STejun Heo * 3627d185af30SYacine Belkadi * Return: 3628401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 3629401a8d04STejun Heo */ 3630401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 36316e84d644SOleg Nesterov { 363236e227d2STejun Heo return __cancel_work_timer(&dwork->work, true); 36336e84d644SOleg Nesterov } 3634f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 36351da177e4SLinus Torvalds 36360fcb78c2SRolf Eike Beer /** 363731ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 3638b6136773SAndrew Morton * @func: the function to call 3639b6136773SAndrew Morton * 364031ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 364131ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 3642b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 364331ddd871STejun Heo * 3644d185af30SYacine Belkadi * Return: 364531ddd871STejun Heo * 0 on success, -errno on failure. 3646b6136773SAndrew Morton */ 364765f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 364815316ba8SChristoph Lameter { 364915316ba8SChristoph Lameter int cpu; 365038f51568SNamhyung Kim struct work_struct __percpu *works; 365115316ba8SChristoph Lameter 3652b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 3653b6136773SAndrew Morton if (!works) 365415316ba8SChristoph Lameter return -ENOMEM; 3655b6136773SAndrew Morton 3656ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 365793981800STejun Heo 365815316ba8SChristoph Lameter for_each_online_cpu(cpu) { 36599bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 36609bfb1839SIngo Molnar 36619bfb1839SIngo Molnar INIT_WORK(work, func); 36628de6d308SOleg Nesterov schedule_work_on(cpu, work); 366315316ba8SChristoph Lameter } 366493981800STejun Heo 366593981800STejun Heo for_each_online_cpu(cpu) 36668616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 366793981800STejun Heo 3668ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 3669b6136773SAndrew Morton free_percpu(works); 367015316ba8SChristoph Lameter return 0; 367115316ba8SChristoph Lameter } 367215316ba8SChristoph Lameter 3673eef6a7d5SAlan Stern /** 36741fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 36751fa44ecaSJames Bottomley * @fn: the function to execute 36761fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 36771fa44ecaSJames Bottomley * be available when the work executes) 36781fa44ecaSJames Bottomley * 36791fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 36801fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 36811fa44ecaSJames Bottomley * 3682d185af30SYacine Belkadi * Return: 0 - function was executed 36831fa44ecaSJames Bottomley * 1 - function was scheduled for execution 36841fa44ecaSJames Bottomley */ 368565f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 36861fa44ecaSJames Bottomley { 36871fa44ecaSJames Bottomley if (!in_interrupt()) { 368865f27f38SDavid Howells fn(&ew->work); 36891fa44ecaSJames Bottomley return 0; 36901fa44ecaSJames Bottomley } 36911fa44ecaSJames Bottomley 369265f27f38SDavid Howells INIT_WORK(&ew->work, fn); 36931fa44ecaSJames Bottomley schedule_work(&ew->work); 36941fa44ecaSJames Bottomley 36951fa44ecaSJames Bottomley return 1; 36961fa44ecaSJames Bottomley } 36971fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 36981fa44ecaSJames Bottomley 36997a4e344cSTejun Heo /** 37007a4e344cSTejun Heo * free_workqueue_attrs - free a workqueue_attrs 37017a4e344cSTejun Heo * @attrs: workqueue_attrs to free 37027a4e344cSTejun Heo * 37037a4e344cSTejun Heo * Undo alloc_workqueue_attrs(). 37047a4e344cSTejun Heo */ 3705513c98d0SDaniel Jordan void free_workqueue_attrs(struct workqueue_attrs *attrs) 37067a4e344cSTejun Heo { 37077a4e344cSTejun Heo if (attrs) { 37087a4e344cSTejun Heo free_cpumask_var(attrs->cpumask); 37099546b29eSTejun Heo free_cpumask_var(attrs->__pod_cpumask); 37107a4e344cSTejun Heo kfree(attrs); 37117a4e344cSTejun Heo } 37127a4e344cSTejun Heo } 37137a4e344cSTejun Heo 37147a4e344cSTejun Heo /** 37157a4e344cSTejun Heo * alloc_workqueue_attrs - allocate a workqueue_attrs 37167a4e344cSTejun Heo * 37177a4e344cSTejun Heo * Allocate a new workqueue_attrs, initialize with default settings and 3718d185af30SYacine Belkadi * return it. 3719d185af30SYacine Belkadi * 3720d185af30SYacine Belkadi * Return: The allocated new workqueue_attr on success. %NULL on failure. 37217a4e344cSTejun Heo */ 3722513c98d0SDaniel Jordan struct workqueue_attrs *alloc_workqueue_attrs(void) 37237a4e344cSTejun Heo { 37247a4e344cSTejun Heo struct workqueue_attrs *attrs; 37257a4e344cSTejun Heo 3726be69d00dSThomas Gleixner attrs = kzalloc(sizeof(*attrs), GFP_KERNEL); 37277a4e344cSTejun Heo if (!attrs) 37287a4e344cSTejun Heo goto fail; 3729be69d00dSThomas Gleixner if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL)) 37307a4e344cSTejun Heo goto fail; 37319546b29eSTejun Heo if (!alloc_cpumask_var(&attrs->__pod_cpumask, GFP_KERNEL)) 37329546b29eSTejun Heo goto fail; 37337a4e344cSTejun Heo 373413e2e556STejun Heo cpumask_copy(attrs->cpumask, cpu_possible_mask); 3735523a301eSTejun Heo attrs->affn_scope = WQ_AFFN_DFL; 37367a4e344cSTejun Heo return attrs; 37377a4e344cSTejun Heo fail: 37387a4e344cSTejun Heo free_workqueue_attrs(attrs); 37397a4e344cSTejun Heo return NULL; 37407a4e344cSTejun Heo } 37417a4e344cSTejun Heo 374229c91e99STejun Heo static void copy_workqueue_attrs(struct workqueue_attrs *to, 374329c91e99STejun Heo const struct workqueue_attrs *from) 374429c91e99STejun Heo { 374529c91e99STejun Heo to->nice = from->nice; 374629c91e99STejun Heo cpumask_copy(to->cpumask, from->cpumask); 37479546b29eSTejun Heo cpumask_copy(to->__pod_cpumask, from->__pod_cpumask); 37488639ecebSTejun Heo to->affn_strict = from->affn_strict; 374984193c07STejun Heo 37502865a8fbSShaohua Li /* 375184193c07STejun Heo * Unlike hash and equality test, copying shouldn't ignore wq-only 375284193c07STejun Heo * fields as copying is used for both pool and wq attrs. Instead, 375384193c07STejun Heo * get_unbound_pool() explicitly clears the fields. 37542865a8fbSShaohua Li */ 375584193c07STejun Heo to->affn_scope = from->affn_scope; 3756af73f5c9STejun Heo to->ordered = from->ordered; 375729c91e99STejun Heo } 375829c91e99STejun Heo 37595de7a03cSTejun Heo /* 37605de7a03cSTejun Heo * Some attrs fields are workqueue-only. Clear them for worker_pool's. See the 37615de7a03cSTejun Heo * comments in 'struct workqueue_attrs' definition. 37625de7a03cSTejun Heo */ 37635de7a03cSTejun Heo static void wqattrs_clear_for_pool(struct workqueue_attrs *attrs) 37645de7a03cSTejun Heo { 376584193c07STejun Heo attrs->affn_scope = WQ_AFFN_NR_TYPES; 37665de7a03cSTejun Heo attrs->ordered = false; 37675de7a03cSTejun Heo } 37685de7a03cSTejun Heo 376929c91e99STejun Heo /* hash value of the content of @attr */ 377029c91e99STejun Heo static u32 wqattrs_hash(const struct workqueue_attrs *attrs) 377129c91e99STejun Heo { 377229c91e99STejun Heo u32 hash = 0; 377329c91e99STejun Heo 377429c91e99STejun Heo hash = jhash_1word(attrs->nice, hash); 377513e2e556STejun Heo hash = jhash(cpumask_bits(attrs->cpumask), 377613e2e556STejun Heo BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); 37779546b29eSTejun Heo hash = jhash(cpumask_bits(attrs->__pod_cpumask), 37789546b29eSTejun Heo BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); 37798639ecebSTejun Heo hash = jhash_1word(attrs->affn_strict, hash); 378029c91e99STejun Heo return hash; 378129c91e99STejun Heo } 378229c91e99STejun Heo 378329c91e99STejun Heo /* content equality test */ 378429c91e99STejun Heo static bool wqattrs_equal(const struct workqueue_attrs *a, 378529c91e99STejun Heo const struct workqueue_attrs *b) 378629c91e99STejun Heo { 378729c91e99STejun Heo if (a->nice != b->nice) 378829c91e99STejun Heo return false; 378929c91e99STejun Heo if (!cpumask_equal(a->cpumask, b->cpumask)) 379029c91e99STejun Heo return false; 37919546b29eSTejun Heo if (!cpumask_equal(a->__pod_cpumask, b->__pod_cpumask)) 37929546b29eSTejun Heo return false; 37938639ecebSTejun Heo if (a->affn_strict != b->affn_strict) 37948639ecebSTejun Heo return false; 379529c91e99STejun Heo return true; 379629c91e99STejun Heo } 379729c91e99STejun Heo 37980f36ee24STejun Heo /* Update @attrs with actually available CPUs */ 37990f36ee24STejun Heo static void wqattrs_actualize_cpumask(struct workqueue_attrs *attrs, 38000f36ee24STejun Heo const cpumask_t *unbound_cpumask) 38010f36ee24STejun Heo { 38020f36ee24STejun Heo /* 38030f36ee24STejun Heo * Calculate the effective CPU mask of @attrs given @unbound_cpumask. If 38040f36ee24STejun Heo * @attrs->cpumask doesn't overlap with @unbound_cpumask, we fallback to 38050f36ee24STejun Heo * @unbound_cpumask. 38060f36ee24STejun Heo */ 38070f36ee24STejun Heo cpumask_and(attrs->cpumask, attrs->cpumask, unbound_cpumask); 38080f36ee24STejun Heo if (unlikely(cpumask_empty(attrs->cpumask))) 38090f36ee24STejun Heo cpumask_copy(attrs->cpumask, unbound_cpumask); 38100f36ee24STejun Heo } 38110f36ee24STejun Heo 381284193c07STejun Heo /* find wq_pod_type to use for @attrs */ 381384193c07STejun Heo static const struct wq_pod_type * 381484193c07STejun Heo wqattrs_pod_type(const struct workqueue_attrs *attrs) 381584193c07STejun Heo { 3816523a301eSTejun Heo enum wq_affn_scope scope; 3817523a301eSTejun Heo struct wq_pod_type *pt; 3818523a301eSTejun Heo 3819523a301eSTejun Heo /* to synchronize access to wq_affn_dfl */ 3820523a301eSTejun Heo lockdep_assert_held(&wq_pool_mutex); 3821523a301eSTejun Heo 3822523a301eSTejun Heo if (attrs->affn_scope == WQ_AFFN_DFL) 3823523a301eSTejun Heo scope = wq_affn_dfl; 3824523a301eSTejun Heo else 3825523a301eSTejun Heo scope = attrs->affn_scope; 3826523a301eSTejun Heo 3827523a301eSTejun Heo pt = &wq_pod_types[scope]; 382884193c07STejun Heo 382984193c07STejun Heo if (!WARN_ON_ONCE(attrs->affn_scope == WQ_AFFN_NR_TYPES) && 383084193c07STejun Heo likely(pt->nr_pods)) 383184193c07STejun Heo return pt; 383284193c07STejun Heo 383384193c07STejun Heo /* 383484193c07STejun Heo * Before workqueue_init_topology(), only SYSTEM is available which is 383584193c07STejun Heo * initialized in workqueue_init_early(). 383684193c07STejun Heo */ 383784193c07STejun Heo pt = &wq_pod_types[WQ_AFFN_SYSTEM]; 383884193c07STejun Heo BUG_ON(!pt->nr_pods); 383984193c07STejun Heo return pt; 384084193c07STejun Heo } 384184193c07STejun Heo 38427a4e344cSTejun Heo /** 38437a4e344cSTejun Heo * init_worker_pool - initialize a newly zalloc'd worker_pool 38447a4e344cSTejun Heo * @pool: worker_pool to initialize 38457a4e344cSTejun Heo * 3846402dd89dSShailendra Verma * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. 3847d185af30SYacine Belkadi * 3848d185af30SYacine Belkadi * Return: 0 on success, -errno on failure. Even on failure, all fields 384929c91e99STejun Heo * inside @pool proper are initialized and put_unbound_pool() can be called 385029c91e99STejun Heo * on @pool safely to release it. 38517a4e344cSTejun Heo */ 38527a4e344cSTejun Heo static int init_worker_pool(struct worker_pool *pool) 38534e1a1f9aSTejun Heo { 3854a9b8a985SSebastian Andrzej Siewior raw_spin_lock_init(&pool->lock); 385529c91e99STejun Heo pool->id = -1; 385629c91e99STejun Heo pool->cpu = -1; 3857f3f90ad4STejun Heo pool->node = NUMA_NO_NODE; 38584e1a1f9aSTejun Heo pool->flags |= POOL_DISASSOCIATED; 385982607adcSTejun Heo pool->watchdog_ts = jiffies; 38604e1a1f9aSTejun Heo INIT_LIST_HEAD(&pool->worklist); 38614e1a1f9aSTejun Heo INIT_LIST_HEAD(&pool->idle_list); 38624e1a1f9aSTejun Heo hash_init(pool->busy_hash); 38634e1a1f9aSTejun Heo 386432a6c723SKees Cook timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE); 38653f959aa3SValentin Schneider INIT_WORK(&pool->idle_cull_work, idle_cull_fn); 38664e1a1f9aSTejun Heo 386732a6c723SKees Cook timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0); 38684e1a1f9aSTejun Heo 3869da028469SLai Jiangshan INIT_LIST_HEAD(&pool->workers); 3870e02b9312SValentin Schneider INIT_LIST_HEAD(&pool->dying_workers); 38717a4e344cSTejun Heo 38727cda9aaeSLai Jiangshan ida_init(&pool->worker_ida); 387329c91e99STejun Heo INIT_HLIST_NODE(&pool->hash_node); 387429c91e99STejun Heo pool->refcnt = 1; 387529c91e99STejun Heo 387629c91e99STejun Heo /* shouldn't fail above this point */ 3877be69d00dSThomas Gleixner pool->attrs = alloc_workqueue_attrs(); 38787a4e344cSTejun Heo if (!pool->attrs) 38797a4e344cSTejun Heo return -ENOMEM; 38805de7a03cSTejun Heo 38815de7a03cSTejun Heo wqattrs_clear_for_pool(pool->attrs); 38825de7a03cSTejun Heo 38837a4e344cSTejun Heo return 0; 38844e1a1f9aSTejun Heo } 38854e1a1f9aSTejun Heo 3886669de8bdSBart Van Assche #ifdef CONFIG_LOCKDEP 3887669de8bdSBart Van Assche static void wq_init_lockdep(struct workqueue_struct *wq) 3888669de8bdSBart Van Assche { 3889669de8bdSBart Van Assche char *lock_name; 3890669de8bdSBart Van Assche 3891669de8bdSBart Van Assche lockdep_register_key(&wq->key); 3892669de8bdSBart Van Assche lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name); 3893669de8bdSBart Van Assche if (!lock_name) 3894669de8bdSBart Van Assche lock_name = wq->name; 389569a106c0SQian Cai 389669a106c0SQian Cai wq->lock_name = lock_name; 3897669de8bdSBart Van Assche lockdep_init_map(&wq->lockdep_map, lock_name, &wq->key, 0); 3898669de8bdSBart Van Assche } 3899669de8bdSBart Van Assche 3900669de8bdSBart Van Assche static void wq_unregister_lockdep(struct workqueue_struct *wq) 3901669de8bdSBart Van Assche { 3902669de8bdSBart Van Assche lockdep_unregister_key(&wq->key); 3903669de8bdSBart Van Assche } 3904669de8bdSBart Van Assche 3905669de8bdSBart Van Assche static void wq_free_lockdep(struct workqueue_struct *wq) 3906669de8bdSBart Van Assche { 3907669de8bdSBart Van Assche if (wq->lock_name != wq->name) 3908669de8bdSBart Van Assche kfree(wq->lock_name); 3909669de8bdSBart Van Assche } 3910669de8bdSBart Van Assche #else 3911669de8bdSBart Van Assche static void wq_init_lockdep(struct workqueue_struct *wq) 3912669de8bdSBart Van Assche { 3913669de8bdSBart Van Assche } 3914669de8bdSBart Van Assche 3915669de8bdSBart Van Assche static void wq_unregister_lockdep(struct workqueue_struct *wq) 3916669de8bdSBart Van Assche { 3917669de8bdSBart Van Assche } 3918669de8bdSBart Van Assche 3919669de8bdSBart Van Assche static void wq_free_lockdep(struct workqueue_struct *wq) 3920669de8bdSBart Van Assche { 3921669de8bdSBart Van Assche } 3922669de8bdSBart Van Assche #endif 3923669de8bdSBart Van Assche 3924e2dca7adSTejun Heo static void rcu_free_wq(struct rcu_head *rcu) 3925e2dca7adSTejun Heo { 3926e2dca7adSTejun Heo struct workqueue_struct *wq = 3927e2dca7adSTejun Heo container_of(rcu, struct workqueue_struct, rcu); 3928e2dca7adSTejun Heo 3929669de8bdSBart Van Assche wq_free_lockdep(wq); 3930ee1ceef7STejun Heo free_percpu(wq->cpu_pwq); 3931e2dca7adSTejun Heo free_workqueue_attrs(wq->unbound_attrs); 3932e2dca7adSTejun Heo kfree(wq); 3933e2dca7adSTejun Heo } 3934e2dca7adSTejun Heo 393529c91e99STejun Heo static void rcu_free_pool(struct rcu_head *rcu) 393629c91e99STejun Heo { 393729c91e99STejun Heo struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); 393829c91e99STejun Heo 39397cda9aaeSLai Jiangshan ida_destroy(&pool->worker_ida); 394029c91e99STejun Heo free_workqueue_attrs(pool->attrs); 394129c91e99STejun Heo kfree(pool); 394229c91e99STejun Heo } 394329c91e99STejun Heo 394429c91e99STejun Heo /** 394529c91e99STejun Heo * put_unbound_pool - put a worker_pool 394629c91e99STejun Heo * @pool: worker_pool to put 394729c91e99STejun Heo * 394824acfb71SThomas Gleixner * Put @pool. If its refcnt reaches zero, it gets destroyed in RCU 3949c5aa87bbSTejun Heo * safe manner. get_unbound_pool() calls this function on its failure path 3950c5aa87bbSTejun Heo * and this function should be able to release pools which went through, 3951c5aa87bbSTejun Heo * successfully or not, init_worker_pool(). 3952a892caccSTejun Heo * 3953a892caccSTejun Heo * Should be called with wq_pool_mutex held. 395429c91e99STejun Heo */ 395529c91e99STejun Heo static void put_unbound_pool(struct worker_pool *pool) 395629c91e99STejun Heo { 395760f5a4bcSLai Jiangshan DECLARE_COMPLETION_ONSTACK(detach_completion); 395829c91e99STejun Heo struct worker *worker; 39599680540cSYang Yingliang LIST_HEAD(cull_list); 3960e02b9312SValentin Schneider 3961a892caccSTejun Heo lockdep_assert_held(&wq_pool_mutex); 3962a892caccSTejun Heo 3963a892caccSTejun Heo if (--pool->refcnt) 396429c91e99STejun Heo return; 396529c91e99STejun Heo 396629c91e99STejun Heo /* sanity checks */ 396761d0fbb4SLai Jiangshan if (WARN_ON(!(pool->cpu < 0)) || 3968a892caccSTejun Heo WARN_ON(!list_empty(&pool->worklist))) 396929c91e99STejun Heo return; 397029c91e99STejun Heo 397129c91e99STejun Heo /* release id and unhash */ 397229c91e99STejun Heo if (pool->id >= 0) 397329c91e99STejun Heo idr_remove(&worker_pool_idr, pool->id); 397429c91e99STejun Heo hash_del(&pool->hash_node); 397529c91e99STejun Heo 3976c5aa87bbSTejun Heo /* 3977692b4825STejun Heo * Become the manager and destroy all workers. This prevents 3978692b4825STejun Heo * @pool's workers from blocking on attach_mutex. We're the last 3979692b4825STejun Heo * manager and @pool gets freed with the flag set. 39809ab03be4SValentin Schneider * 39819ab03be4SValentin Schneider * Having a concurrent manager is quite unlikely to happen as we can 39829ab03be4SValentin Schneider * only get here with 39839ab03be4SValentin Schneider * pwq->refcnt == pool->refcnt == 0 39849ab03be4SValentin Schneider * which implies no work queued to the pool, which implies no worker can 39859ab03be4SValentin Schneider * become the manager. However a worker could have taken the role of 39869ab03be4SValentin Schneider * manager before the refcnts dropped to 0, since maybe_create_worker() 39879ab03be4SValentin Schneider * drops pool->lock 3988c5aa87bbSTejun Heo */ 39899ab03be4SValentin Schneider while (true) { 39909ab03be4SValentin Schneider rcuwait_wait_event(&manager_wait, 39919ab03be4SValentin Schneider !(pool->flags & POOL_MANAGER_ACTIVE), 3992d8bb65abSSebastian Andrzej Siewior TASK_UNINTERRUPTIBLE); 3993e02b9312SValentin Schneider 3994e02b9312SValentin Schneider mutex_lock(&wq_pool_attach_mutex); 39959ab03be4SValentin Schneider raw_spin_lock_irq(&pool->lock); 39969ab03be4SValentin Schneider if (!(pool->flags & POOL_MANAGER_ACTIVE)) { 3997692b4825STejun Heo pool->flags |= POOL_MANAGER_ACTIVE; 39989ab03be4SValentin Schneider break; 39999ab03be4SValentin Schneider } 40009ab03be4SValentin Schneider raw_spin_unlock_irq(&pool->lock); 4001e02b9312SValentin Schneider mutex_unlock(&wq_pool_attach_mutex); 40029ab03be4SValentin Schneider } 4003692b4825STejun Heo 40041037de36SLai Jiangshan while ((worker = first_idle_worker(pool))) 4005e02b9312SValentin Schneider set_worker_dying(worker, &cull_list); 400629c91e99STejun Heo WARN_ON(pool->nr_workers || pool->nr_idle); 4007a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 400860f5a4bcSLai Jiangshan 4009e02b9312SValentin Schneider wake_dying_workers(&cull_list); 4010e02b9312SValentin Schneider 4011e02b9312SValentin Schneider if (!list_empty(&pool->workers) || !list_empty(&pool->dying_workers)) 401260f5a4bcSLai Jiangshan pool->detach_completion = &detach_completion; 40131258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 401460f5a4bcSLai Jiangshan 401560f5a4bcSLai Jiangshan if (pool->detach_completion) 401660f5a4bcSLai Jiangshan wait_for_completion(pool->detach_completion); 401760f5a4bcSLai Jiangshan 401829c91e99STejun Heo /* shut down the timers */ 401929c91e99STejun Heo del_timer_sync(&pool->idle_timer); 40203f959aa3SValentin Schneider cancel_work_sync(&pool->idle_cull_work); 402129c91e99STejun Heo del_timer_sync(&pool->mayday_timer); 402229c91e99STejun Heo 402324acfb71SThomas Gleixner /* RCU protected to allow dereferences from get_work_pool() */ 402425b00775SPaul E. McKenney call_rcu(&pool->rcu, rcu_free_pool); 402529c91e99STejun Heo } 402629c91e99STejun Heo 402729c91e99STejun Heo /** 402829c91e99STejun Heo * get_unbound_pool - get a worker_pool with the specified attributes 402929c91e99STejun Heo * @attrs: the attributes of the worker_pool to get 403029c91e99STejun Heo * 403129c91e99STejun Heo * Obtain a worker_pool which has the same attributes as @attrs, bump the 403229c91e99STejun Heo * reference count and return it. If there already is a matching 403329c91e99STejun Heo * worker_pool, it will be used; otherwise, this function attempts to 4034d185af30SYacine Belkadi * create a new one. 4035a892caccSTejun Heo * 4036a892caccSTejun Heo * Should be called with wq_pool_mutex held. 4037d185af30SYacine Belkadi * 4038d185af30SYacine Belkadi * Return: On success, a worker_pool with the same attributes as @attrs. 4039d185af30SYacine Belkadi * On failure, %NULL. 404029c91e99STejun Heo */ 404129c91e99STejun Heo static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) 404229c91e99STejun Heo { 404384193c07STejun Heo struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_NUMA]; 404429c91e99STejun Heo u32 hash = wqattrs_hash(attrs); 404529c91e99STejun Heo struct worker_pool *pool; 404684193c07STejun Heo int pod, node = NUMA_NO_NODE; 404729c91e99STejun Heo 4048a892caccSTejun Heo lockdep_assert_held(&wq_pool_mutex); 404929c91e99STejun Heo 405029c91e99STejun Heo /* do we already have a matching pool? */ 405129c91e99STejun Heo hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { 405229c91e99STejun Heo if (wqattrs_equal(pool->attrs, attrs)) { 405329c91e99STejun Heo pool->refcnt++; 40543fb1823cSLai Jiangshan return pool; 405529c91e99STejun Heo } 405629c91e99STejun Heo } 405729c91e99STejun Heo 40589546b29eSTejun Heo /* If __pod_cpumask is contained inside a NUMA pod, that's our node */ 405984193c07STejun Heo for (pod = 0; pod < pt->nr_pods; pod++) { 40609546b29eSTejun Heo if (cpumask_subset(attrs->__pod_cpumask, pt->pod_cpus[pod])) { 406184193c07STejun Heo node = pt->pod_node[pod]; 4062e2273584SXunlei Pang break; 4063e2273584SXunlei Pang } 4064e2273584SXunlei Pang } 4065e2273584SXunlei Pang 406629c91e99STejun Heo /* nope, create a new one */ 406784193c07STejun Heo pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, node); 406829c91e99STejun Heo if (!pool || init_worker_pool(pool) < 0) 406929c91e99STejun Heo goto fail; 407029c91e99STejun Heo 407184193c07STejun Heo pool->node = node; 40725de7a03cSTejun Heo copy_workqueue_attrs(pool->attrs, attrs); 40735de7a03cSTejun Heo wqattrs_clear_for_pool(pool->attrs); 40742865a8fbSShaohua Li 407529c91e99STejun Heo if (worker_pool_assign_id(pool) < 0) 407629c91e99STejun Heo goto fail; 407729c91e99STejun Heo 407829c91e99STejun Heo /* create and start the initial worker */ 40793347fa09STejun Heo if (wq_online && !create_worker(pool)) 408029c91e99STejun Heo goto fail; 408129c91e99STejun Heo 408229c91e99STejun Heo /* install */ 408329c91e99STejun Heo hash_add(unbound_pool_hash, &pool->hash_node, hash); 40843fb1823cSLai Jiangshan 408529c91e99STejun Heo return pool; 408629c91e99STejun Heo fail: 408729c91e99STejun Heo if (pool) 408829c91e99STejun Heo put_unbound_pool(pool); 408929c91e99STejun Heo return NULL; 409029c91e99STejun Heo } 409129c91e99STejun Heo 40928864b4e5STejun Heo static void rcu_free_pwq(struct rcu_head *rcu) 40938864b4e5STejun Heo { 40948864b4e5STejun Heo kmem_cache_free(pwq_cache, 40958864b4e5STejun Heo container_of(rcu, struct pool_workqueue, rcu)); 40968864b4e5STejun Heo } 40978864b4e5STejun Heo 40988864b4e5STejun Heo /* 4099967b494eSTejun Heo * Scheduled on pwq_release_worker by put_pwq() when an unbound pwq hits zero 4100967b494eSTejun Heo * refcnt and needs to be destroyed. 41018864b4e5STejun Heo */ 4102687a9aa5STejun Heo static void pwq_release_workfn(struct kthread_work *work) 41038864b4e5STejun Heo { 41048864b4e5STejun Heo struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, 4105687a9aa5STejun Heo release_work); 41068864b4e5STejun Heo struct workqueue_struct *wq = pwq->wq; 41078864b4e5STejun Heo struct worker_pool *pool = pwq->pool; 4108b42b0bddSYang Yingliang bool is_last = false; 41098864b4e5STejun Heo 4110b42b0bddSYang Yingliang /* 4111687a9aa5STejun Heo * When @pwq is not linked, it doesn't hold any reference to the 4112b42b0bddSYang Yingliang * @wq, and @wq is invalid to access. 4113b42b0bddSYang Yingliang */ 4114b42b0bddSYang Yingliang if (!list_empty(&pwq->pwqs_node)) { 41153c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 41168864b4e5STejun Heo list_del_rcu(&pwq->pwqs_node); 4117bc0caf09STejun Heo is_last = list_empty(&wq->pwqs); 41183c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 4119b42b0bddSYang Yingliang } 41208864b4e5STejun Heo 4121687a9aa5STejun Heo if (wq->flags & WQ_UNBOUND) { 4122a892caccSTejun Heo mutex_lock(&wq_pool_mutex); 41238864b4e5STejun Heo put_unbound_pool(pool); 4124a892caccSTejun Heo mutex_unlock(&wq_pool_mutex); 4125687a9aa5STejun Heo } 4126a892caccSTejun Heo 412725b00775SPaul E. McKenney call_rcu(&pwq->rcu, rcu_free_pwq); 41288864b4e5STejun Heo 41298864b4e5STejun Heo /* 41308864b4e5STejun Heo * If we're the last pwq going away, @wq is already dead and no one 4131e2dca7adSTejun Heo * is gonna access it anymore. Schedule RCU free. 41328864b4e5STejun Heo */ 4133669de8bdSBart Van Assche if (is_last) { 4134669de8bdSBart Van Assche wq_unregister_lockdep(wq); 413525b00775SPaul E. McKenney call_rcu(&wq->rcu, rcu_free_wq); 41366029a918STejun Heo } 4137669de8bdSBart Van Assche } 41388864b4e5STejun Heo 41390fbd95aaSTejun Heo /** 4140699ce097STejun Heo * pwq_adjust_max_active - update a pwq's max_active to the current setting 41410fbd95aaSTejun Heo * @pwq: target pool_workqueue 41420fbd95aaSTejun Heo * 4143699ce097STejun Heo * If @pwq isn't freezing, set @pwq->max_active to the associated 4144f97a4a1aSLai Jiangshan * workqueue's saved_max_active and activate inactive work items 4145699ce097STejun Heo * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. 41460fbd95aaSTejun Heo */ 4147699ce097STejun Heo static void pwq_adjust_max_active(struct pool_workqueue *pwq) 41480fbd95aaSTejun Heo { 4149699ce097STejun Heo struct workqueue_struct *wq = pwq->wq; 4150699ce097STejun Heo bool freezable = wq->flags & WQ_FREEZABLE; 41513347fa09STejun Heo unsigned long flags; 4152699ce097STejun Heo 4153699ce097STejun Heo /* for @wq->saved_max_active */ 4154a357fc03SLai Jiangshan lockdep_assert_held(&wq->mutex); 4155699ce097STejun Heo 4156699ce097STejun Heo /* fast exit for non-freezable wqs */ 4157699ce097STejun Heo if (!freezable && pwq->max_active == wq->saved_max_active) 4158699ce097STejun Heo return; 4159699ce097STejun Heo 41603347fa09STejun Heo /* this function can be called during early boot w/ irq disabled */ 4161a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irqsave(&pwq->pool->lock, flags); 4162699ce097STejun Heo 416374b414eaSLai Jiangshan /* 416474b414eaSLai Jiangshan * During [un]freezing, the caller is responsible for ensuring that 416574b414eaSLai Jiangshan * this function is called at least once after @workqueue_freezing 416674b414eaSLai Jiangshan * is updated and visible. 416774b414eaSLai Jiangshan */ 416874b414eaSLai Jiangshan if (!freezable || !workqueue_freezing) { 4169699ce097STejun Heo pwq->max_active = wq->saved_max_active; 41700fbd95aaSTejun Heo 4171f97a4a1aSLai Jiangshan while (!list_empty(&pwq->inactive_works) && 41720219a352STejun Heo pwq->nr_active < pwq->max_active) 4173f97a4a1aSLai Jiangshan pwq_activate_first_inactive(pwq); 4174951a078aSLai Jiangshan 41750219a352STejun Heo kick_pool(pwq->pool); 4176699ce097STejun Heo } else { 4177699ce097STejun Heo pwq->max_active = 0; 4178699ce097STejun Heo } 4179699ce097STejun Heo 4180a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); 41810fbd95aaSTejun Heo } 41820fbd95aaSTejun Heo 418367dc8325SCai Huoqing /* initialize newly allocated @pwq which is associated with @wq and @pool */ 4184f147f29eSTejun Heo static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, 4185f147f29eSTejun Heo struct worker_pool *pool) 4186d2c1d404STejun Heo { 4187d2c1d404STejun Heo BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); 4188d2c1d404STejun Heo 4189e50aba9aSTejun Heo memset(pwq, 0, sizeof(*pwq)); 4190e50aba9aSTejun Heo 4191d2c1d404STejun Heo pwq->pool = pool; 4192d2c1d404STejun Heo pwq->wq = wq; 4193d2c1d404STejun Heo pwq->flush_color = -1; 41948864b4e5STejun Heo pwq->refcnt = 1; 4195f97a4a1aSLai Jiangshan INIT_LIST_HEAD(&pwq->inactive_works); 41961befcf30STejun Heo INIT_LIST_HEAD(&pwq->pwqs_node); 4197d2c1d404STejun Heo INIT_LIST_HEAD(&pwq->mayday_node); 4198687a9aa5STejun Heo kthread_init_work(&pwq->release_work, pwq_release_workfn); 4199f147f29eSTejun Heo } 4200d2c1d404STejun Heo 4201f147f29eSTejun Heo /* sync @pwq with the current state of its associated wq and link it */ 42021befcf30STejun Heo static void link_pwq(struct pool_workqueue *pwq) 4203f147f29eSTejun Heo { 4204f147f29eSTejun Heo struct workqueue_struct *wq = pwq->wq; 4205f147f29eSTejun Heo 4206f147f29eSTejun Heo lockdep_assert_held(&wq->mutex); 420775ccf595STejun Heo 42081befcf30STejun Heo /* may be called multiple times, ignore if already linked */ 42091befcf30STejun Heo if (!list_empty(&pwq->pwqs_node)) 42101befcf30STejun Heo return; 42111befcf30STejun Heo 421229b1cb41SLai Jiangshan /* set the matching work_color */ 421375ccf595STejun Heo pwq->work_color = wq->work_color; 4214983ca25eSTejun Heo 4215983ca25eSTejun Heo /* sync max_active to the current setting */ 4216983ca25eSTejun Heo pwq_adjust_max_active(pwq); 4217983ca25eSTejun Heo 4218983ca25eSTejun Heo /* link in @pwq */ 42199e8cd2f5STejun Heo list_add_rcu(&pwq->pwqs_node, &wq->pwqs); 4220df2d5ae4STejun Heo } 42216029a918STejun Heo 4222f147f29eSTejun Heo /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ 4223f147f29eSTejun Heo static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, 4224f147f29eSTejun Heo const struct workqueue_attrs *attrs) 4225f147f29eSTejun Heo { 4226f147f29eSTejun Heo struct worker_pool *pool; 4227f147f29eSTejun Heo struct pool_workqueue *pwq; 4228f147f29eSTejun Heo 4229f147f29eSTejun Heo lockdep_assert_held(&wq_pool_mutex); 4230f147f29eSTejun Heo 4231f147f29eSTejun Heo pool = get_unbound_pool(attrs); 4232f147f29eSTejun Heo if (!pool) 4233f147f29eSTejun Heo return NULL; 4234f147f29eSTejun Heo 4235e50aba9aSTejun Heo pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); 4236f147f29eSTejun Heo if (!pwq) { 4237f147f29eSTejun Heo put_unbound_pool(pool); 4238f147f29eSTejun Heo return NULL; 4239f147f29eSTejun Heo } 4240f147f29eSTejun Heo 4241f147f29eSTejun Heo init_pwq(pwq, wq, pool); 4242f147f29eSTejun Heo return pwq; 4243d2c1d404STejun Heo } 4244d2c1d404STejun Heo 42454c16bd32STejun Heo /** 4246fef59c9cSTejun Heo * wq_calc_pod_cpumask - calculate a wq_attrs' cpumask for a pod 4247042f7df1SLai Jiangshan * @attrs: the wq_attrs of the default pwq of the target workqueue 424884193c07STejun Heo * @cpu: the target CPU 42494c16bd32STejun Heo * @cpu_going_down: if >= 0, the CPU to consider as offline 42504c16bd32STejun Heo * 4251fef59c9cSTejun Heo * Calculate the cpumask a workqueue with @attrs should use on @pod. If 4252fef59c9cSTejun Heo * @cpu_going_down is >= 0, that cpu is considered offline during calculation. 42539546b29eSTejun Heo * The result is stored in @attrs->__pod_cpumask. 42544c16bd32STejun Heo * 4255fef59c9cSTejun Heo * If pod affinity is not enabled, @attrs->cpumask is always used. If enabled 4256fef59c9cSTejun Heo * and @pod has online CPUs requested by @attrs, the returned cpumask is the 4257fef59c9cSTejun Heo * intersection of the possible CPUs of @pod and @attrs->cpumask. 42584c16bd32STejun Heo * 4259fef59c9cSTejun Heo * The caller is responsible for ensuring that the cpumask of @pod stays stable. 42604c16bd32STejun Heo */ 42619546b29eSTejun Heo static void wq_calc_pod_cpumask(struct workqueue_attrs *attrs, int cpu, 42629546b29eSTejun Heo int cpu_going_down) 42634c16bd32STejun Heo { 426484193c07STejun Heo const struct wq_pod_type *pt = wqattrs_pod_type(attrs); 426584193c07STejun Heo int pod = pt->cpu_pod[cpu]; 42664c16bd32STejun Heo 4267fef59c9cSTejun Heo /* does @pod have any online CPUs @attrs wants? */ 42689546b29eSTejun Heo cpumask_and(attrs->__pod_cpumask, pt->pod_cpus[pod], attrs->cpumask); 42699546b29eSTejun Heo cpumask_and(attrs->__pod_cpumask, attrs->__pod_cpumask, cpu_online_mask); 42704c16bd32STejun Heo if (cpu_going_down >= 0) 42719546b29eSTejun Heo cpumask_clear_cpu(cpu_going_down, attrs->__pod_cpumask); 42724c16bd32STejun Heo 42739546b29eSTejun Heo if (cpumask_empty(attrs->__pod_cpumask)) { 42749546b29eSTejun Heo cpumask_copy(attrs->__pod_cpumask, attrs->cpumask); 427584193c07STejun Heo return; 427684193c07STejun Heo } 42774c16bd32STejun Heo 4278fef59c9cSTejun Heo /* yeap, return possible CPUs in @pod that @attrs wants */ 42799546b29eSTejun Heo cpumask_and(attrs->__pod_cpumask, attrs->cpumask, pt->pod_cpus[pod]); 42801ad0f0a7SMichael Bringmann 42819546b29eSTejun Heo if (cpumask_empty(attrs->__pod_cpumask)) 42821ad0f0a7SMichael Bringmann pr_warn_once("WARNING: workqueue cpumask: online intersect > " 42831ad0f0a7SMichael Bringmann "possible intersect\n"); 42844c16bd32STejun Heo } 42854c16bd32STejun Heo 4286636b927eSTejun Heo /* install @pwq into @wq's cpu_pwq and return the old pwq */ 4287636b927eSTejun Heo static struct pool_workqueue *install_unbound_pwq(struct workqueue_struct *wq, 4288636b927eSTejun Heo int cpu, struct pool_workqueue *pwq) 42891befcf30STejun Heo { 42901befcf30STejun Heo struct pool_workqueue *old_pwq; 42911befcf30STejun Heo 42925b95e1afSLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 42931befcf30STejun Heo lockdep_assert_held(&wq->mutex); 42941befcf30STejun Heo 42951befcf30STejun Heo /* link_pwq() can handle duplicate calls */ 42961befcf30STejun Heo link_pwq(pwq); 42971befcf30STejun Heo 4298636b927eSTejun Heo old_pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu)); 4299636b927eSTejun Heo rcu_assign_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu), pwq); 43001befcf30STejun Heo return old_pwq; 43011befcf30STejun Heo } 43021befcf30STejun Heo 43032d5f0764SLai Jiangshan /* context to store the prepared attrs & pwqs before applying */ 43042d5f0764SLai Jiangshan struct apply_wqattrs_ctx { 43052d5f0764SLai Jiangshan struct workqueue_struct *wq; /* target workqueue */ 43062d5f0764SLai Jiangshan struct workqueue_attrs *attrs; /* attrs to apply */ 4307042f7df1SLai Jiangshan struct list_head list; /* queued for batching commit */ 43082d5f0764SLai Jiangshan struct pool_workqueue *dfl_pwq; 43092d5f0764SLai Jiangshan struct pool_workqueue *pwq_tbl[]; 43102d5f0764SLai Jiangshan }; 43112d5f0764SLai Jiangshan 43122d5f0764SLai Jiangshan /* free the resources after success or abort */ 43132d5f0764SLai Jiangshan static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) 43142d5f0764SLai Jiangshan { 43152d5f0764SLai Jiangshan if (ctx) { 4316636b927eSTejun Heo int cpu; 43172d5f0764SLai Jiangshan 4318636b927eSTejun Heo for_each_possible_cpu(cpu) 4319636b927eSTejun Heo put_pwq_unlocked(ctx->pwq_tbl[cpu]); 43202d5f0764SLai Jiangshan put_pwq_unlocked(ctx->dfl_pwq); 43212d5f0764SLai Jiangshan 43222d5f0764SLai Jiangshan free_workqueue_attrs(ctx->attrs); 43232d5f0764SLai Jiangshan 43242d5f0764SLai Jiangshan kfree(ctx); 43252d5f0764SLai Jiangshan } 43262d5f0764SLai Jiangshan } 43272d5f0764SLai Jiangshan 43282d5f0764SLai Jiangshan /* allocate the attrs and pwqs for later installation */ 43292d5f0764SLai Jiangshan static struct apply_wqattrs_ctx * 43302d5f0764SLai Jiangshan apply_wqattrs_prepare(struct workqueue_struct *wq, 433199c621efSLai Jiangshan const struct workqueue_attrs *attrs, 433299c621efSLai Jiangshan const cpumask_var_t unbound_cpumask) 43332d5f0764SLai Jiangshan { 43342d5f0764SLai Jiangshan struct apply_wqattrs_ctx *ctx; 43359546b29eSTejun Heo struct workqueue_attrs *new_attrs; 4336636b927eSTejun Heo int cpu; 43372d5f0764SLai Jiangshan 43382d5f0764SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 43392d5f0764SLai Jiangshan 434084193c07STejun Heo if (WARN_ON(attrs->affn_scope < 0 || 434184193c07STejun Heo attrs->affn_scope >= WQ_AFFN_NR_TYPES)) 434284193c07STejun Heo return ERR_PTR(-EINVAL); 434384193c07STejun Heo 4344636b927eSTejun Heo ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_cpu_ids), GFP_KERNEL); 43452d5f0764SLai Jiangshan 4346be69d00dSThomas Gleixner new_attrs = alloc_workqueue_attrs(); 43479546b29eSTejun Heo if (!ctx || !new_attrs) 43482d5f0764SLai Jiangshan goto out_free; 43492d5f0764SLai Jiangshan 4350042f7df1SLai Jiangshan /* 43512d5f0764SLai Jiangshan * If something goes wrong during CPU up/down, we'll fall back to 43522d5f0764SLai Jiangshan * the default pwq covering whole @attrs->cpumask. Always create 43532d5f0764SLai Jiangshan * it even if we don't use it immediately. 43542d5f0764SLai Jiangshan */ 43550f36ee24STejun Heo copy_workqueue_attrs(new_attrs, attrs); 43560f36ee24STejun Heo wqattrs_actualize_cpumask(new_attrs, unbound_cpumask); 43579546b29eSTejun Heo cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask); 43582d5f0764SLai Jiangshan ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs); 43592d5f0764SLai Jiangshan if (!ctx->dfl_pwq) 43602d5f0764SLai Jiangshan goto out_free; 43612d5f0764SLai Jiangshan 4362636b927eSTejun Heo for_each_possible_cpu(cpu) { 4363af73f5c9STejun Heo if (new_attrs->ordered) { 43642d5f0764SLai Jiangshan ctx->dfl_pwq->refcnt++; 4365636b927eSTejun Heo ctx->pwq_tbl[cpu] = ctx->dfl_pwq; 4366636b927eSTejun Heo } else { 43679546b29eSTejun Heo wq_calc_pod_cpumask(new_attrs, cpu, -1); 43689546b29eSTejun Heo ctx->pwq_tbl[cpu] = alloc_unbound_pwq(wq, new_attrs); 4369636b927eSTejun Heo if (!ctx->pwq_tbl[cpu]) 4370636b927eSTejun Heo goto out_free; 43712d5f0764SLai Jiangshan } 43722d5f0764SLai Jiangshan } 43732d5f0764SLai Jiangshan 4374042f7df1SLai Jiangshan /* save the user configured attrs and sanitize it. */ 4375042f7df1SLai Jiangshan copy_workqueue_attrs(new_attrs, attrs); 4376042f7df1SLai Jiangshan cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); 43779546b29eSTejun Heo cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask); 43782d5f0764SLai Jiangshan ctx->attrs = new_attrs; 4379042f7df1SLai Jiangshan 43802d5f0764SLai Jiangshan ctx->wq = wq; 43812d5f0764SLai Jiangshan return ctx; 43822d5f0764SLai Jiangshan 43832d5f0764SLai Jiangshan out_free: 43842d5f0764SLai Jiangshan free_workqueue_attrs(new_attrs); 43852d5f0764SLai Jiangshan apply_wqattrs_cleanup(ctx); 438684193c07STejun Heo return ERR_PTR(-ENOMEM); 43872d5f0764SLai Jiangshan } 43882d5f0764SLai Jiangshan 43892d5f0764SLai Jiangshan /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ 43902d5f0764SLai Jiangshan static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) 43912d5f0764SLai Jiangshan { 4392636b927eSTejun Heo int cpu; 43932d5f0764SLai Jiangshan 43942d5f0764SLai Jiangshan /* all pwqs have been created successfully, let's install'em */ 43952d5f0764SLai Jiangshan mutex_lock(&ctx->wq->mutex); 43962d5f0764SLai Jiangshan 43972d5f0764SLai Jiangshan copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs); 43982d5f0764SLai Jiangshan 43992d5f0764SLai Jiangshan /* save the previous pwq and install the new one */ 4400636b927eSTejun Heo for_each_possible_cpu(cpu) 4401636b927eSTejun Heo ctx->pwq_tbl[cpu] = install_unbound_pwq(ctx->wq, cpu, 4402636b927eSTejun Heo ctx->pwq_tbl[cpu]); 44032d5f0764SLai Jiangshan 44042d5f0764SLai Jiangshan /* @dfl_pwq might not have been used, ensure it's linked */ 44052d5f0764SLai Jiangshan link_pwq(ctx->dfl_pwq); 44062d5f0764SLai Jiangshan swap(ctx->wq->dfl_pwq, ctx->dfl_pwq); 44072d5f0764SLai Jiangshan 44082d5f0764SLai Jiangshan mutex_unlock(&ctx->wq->mutex); 44092d5f0764SLai Jiangshan } 44102d5f0764SLai Jiangshan 4411a0111cf6SLai Jiangshan static void apply_wqattrs_lock(void) 4412a0111cf6SLai Jiangshan { 4413a0111cf6SLai Jiangshan /* CPUs should stay stable across pwq creations and installations */ 4414ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 4415a0111cf6SLai Jiangshan mutex_lock(&wq_pool_mutex); 4416a0111cf6SLai Jiangshan } 4417a0111cf6SLai Jiangshan 4418a0111cf6SLai Jiangshan static void apply_wqattrs_unlock(void) 4419a0111cf6SLai Jiangshan { 4420a0111cf6SLai Jiangshan mutex_unlock(&wq_pool_mutex); 4421ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 4422a0111cf6SLai Jiangshan } 4423a0111cf6SLai Jiangshan 4424a0111cf6SLai Jiangshan static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, 4425a0111cf6SLai Jiangshan const struct workqueue_attrs *attrs) 4426a0111cf6SLai Jiangshan { 4427a0111cf6SLai Jiangshan struct apply_wqattrs_ctx *ctx; 4428a0111cf6SLai Jiangshan 4429a0111cf6SLai Jiangshan /* only unbound workqueues can change attributes */ 4430a0111cf6SLai Jiangshan if (WARN_ON(!(wq->flags & WQ_UNBOUND))) 4431a0111cf6SLai Jiangshan return -EINVAL; 4432a0111cf6SLai Jiangshan 4433a0111cf6SLai Jiangshan /* creating multiple pwqs breaks ordering guarantee */ 44340a94efb5STejun Heo if (!list_empty(&wq->pwqs)) { 44350a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 4436a0111cf6SLai Jiangshan return -EINVAL; 4437a0111cf6SLai Jiangshan 44380a94efb5STejun Heo wq->flags &= ~__WQ_ORDERED; 44390a94efb5STejun Heo } 44400a94efb5STejun Heo 444199c621efSLai Jiangshan ctx = apply_wqattrs_prepare(wq, attrs, wq_unbound_cpumask); 444284193c07STejun Heo if (IS_ERR(ctx)) 444384193c07STejun Heo return PTR_ERR(ctx); 4444a0111cf6SLai Jiangshan 4445a0111cf6SLai Jiangshan /* the ctx has been prepared successfully, let's commit it */ 4446a0111cf6SLai Jiangshan apply_wqattrs_commit(ctx); 4447a0111cf6SLai Jiangshan apply_wqattrs_cleanup(ctx); 4448a0111cf6SLai Jiangshan 44496201171eSwanghaibin return 0; 4450a0111cf6SLai Jiangshan } 4451a0111cf6SLai Jiangshan 44529e8cd2f5STejun Heo /** 44539e8cd2f5STejun Heo * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue 44549e8cd2f5STejun Heo * @wq: the target workqueue 44559e8cd2f5STejun Heo * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() 44569e8cd2f5STejun Heo * 4457fef59c9cSTejun Heo * Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps 4458fef59c9cSTejun Heo * a separate pwq to each CPU pod with possibles CPUs in @attrs->cpumask so that 4459fef59c9cSTejun Heo * work items are affine to the pod it was issued on. Older pwqs are released as 4460fef59c9cSTejun Heo * in-flight work items finish. Note that a work item which repeatedly requeues 4461fef59c9cSTejun Heo * itself back-to-back will stay on its current pwq. 44629e8cd2f5STejun Heo * 4463d185af30SYacine Belkadi * Performs GFP_KERNEL allocations. 4464d185af30SYacine Belkadi * 4465ffd8bea8SSebastian Andrzej Siewior * Assumes caller has CPU hotplug read exclusion, i.e. cpus_read_lock(). 4466509b3204SDaniel Jordan * 4467d185af30SYacine Belkadi * Return: 0 on success and -errno on failure. 44689e8cd2f5STejun Heo */ 4469513c98d0SDaniel Jordan int apply_workqueue_attrs(struct workqueue_struct *wq, 44709e8cd2f5STejun Heo const struct workqueue_attrs *attrs) 44719e8cd2f5STejun Heo { 4472a0111cf6SLai Jiangshan int ret; 44739e8cd2f5STejun Heo 4474509b3204SDaniel Jordan lockdep_assert_cpus_held(); 4475509b3204SDaniel Jordan 4476509b3204SDaniel Jordan mutex_lock(&wq_pool_mutex); 4477a0111cf6SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 4478509b3204SDaniel Jordan mutex_unlock(&wq_pool_mutex); 44792d5f0764SLai Jiangshan 44802d5f0764SLai Jiangshan return ret; 44819e8cd2f5STejun Heo } 44829e8cd2f5STejun Heo 44834c16bd32STejun Heo /** 4484fef59c9cSTejun Heo * wq_update_pod - update pod affinity of a wq for CPU hot[un]plug 44854c16bd32STejun Heo * @wq: the target workqueue 44864cbfd3deSTejun Heo * @cpu: the CPU to update pool association for 44874cbfd3deSTejun Heo * @hotplug_cpu: the CPU coming up or going down 44884c16bd32STejun Heo * @online: whether @cpu is coming up or going down 44894c16bd32STejun Heo * 44904c16bd32STejun Heo * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and 4491fef59c9cSTejun Heo * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update pod affinity of 44924c16bd32STejun Heo * @wq accordingly. 44934c16bd32STejun Heo * 44944c16bd32STejun Heo * 4495fef59c9cSTejun Heo * If pod affinity can't be adjusted due to memory allocation failure, it falls 4496fef59c9cSTejun Heo * back to @wq->dfl_pwq which may not be optimal but is always correct. 4497fef59c9cSTejun Heo * 4498fef59c9cSTejun Heo * Note that when the last allowed CPU of a pod goes offline for a workqueue 4499fef59c9cSTejun Heo * with a cpumask spanning multiple pods, the workers which were already 4500fef59c9cSTejun Heo * executing the work items for the workqueue will lose their CPU affinity and 4501fef59c9cSTejun Heo * may execute on any CPU. This is similar to how per-cpu workqueues behave on 4502fef59c9cSTejun Heo * CPU_DOWN. If a workqueue user wants strict affinity, it's the user's 4503fef59c9cSTejun Heo * responsibility to flush the work item from CPU_DOWN_PREPARE. 45044c16bd32STejun Heo */ 4505fef59c9cSTejun Heo static void wq_update_pod(struct workqueue_struct *wq, int cpu, 45064cbfd3deSTejun Heo int hotplug_cpu, bool online) 45074c16bd32STejun Heo { 45084cbfd3deSTejun Heo int off_cpu = online ? -1 : hotplug_cpu; 45094c16bd32STejun Heo struct pool_workqueue *old_pwq = NULL, *pwq; 45104c16bd32STejun Heo struct workqueue_attrs *target_attrs; 45114c16bd32STejun Heo 45124c16bd32STejun Heo lockdep_assert_held(&wq_pool_mutex); 45134c16bd32STejun Heo 451484193c07STejun Heo if (!(wq->flags & WQ_UNBOUND) || wq->unbound_attrs->ordered) 45154c16bd32STejun Heo return; 45164c16bd32STejun Heo 45174c16bd32STejun Heo /* 45184c16bd32STejun Heo * We don't wanna alloc/free wq_attrs for each wq for each CPU. 45194c16bd32STejun Heo * Let's use a preallocated one. The following buf is protected by 45204c16bd32STejun Heo * CPU hotplug exclusion. 45214c16bd32STejun Heo */ 4522fef59c9cSTejun Heo target_attrs = wq_update_pod_attrs_buf; 45234c16bd32STejun Heo 45244c16bd32STejun Heo copy_workqueue_attrs(target_attrs, wq->unbound_attrs); 45250f36ee24STejun Heo wqattrs_actualize_cpumask(target_attrs, wq_unbound_cpumask); 45264c16bd32STejun Heo 4527636b927eSTejun Heo /* nothing to do if the target cpumask matches the current pwq */ 45289546b29eSTejun Heo wq_calc_pod_cpumask(target_attrs, cpu, off_cpu); 4529636b927eSTejun Heo pwq = rcu_dereference_protected(*per_cpu_ptr(wq->cpu_pwq, cpu), 4530636b927eSTejun Heo lockdep_is_held(&wq_pool_mutex)); 45319546b29eSTejun Heo if (wqattrs_equal(target_attrs, pwq->pool->attrs)) 4532f7142ed4SLai Jiangshan return; 45334c16bd32STejun Heo 45344c16bd32STejun Heo /* create a new pwq */ 45354c16bd32STejun Heo pwq = alloc_unbound_pwq(wq, target_attrs); 45364c16bd32STejun Heo if (!pwq) { 4537fef59c9cSTejun Heo pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n", 45384c16bd32STejun Heo wq->name); 453977f300b1SDaeseok Youn goto use_dfl_pwq; 45404c16bd32STejun Heo } 45414c16bd32STejun Heo 4542f7142ed4SLai Jiangshan /* Install the new pwq. */ 45434c16bd32STejun Heo mutex_lock(&wq->mutex); 4544636b927eSTejun Heo old_pwq = install_unbound_pwq(wq, cpu, pwq); 45454c16bd32STejun Heo goto out_unlock; 45464c16bd32STejun Heo 45474c16bd32STejun Heo use_dfl_pwq: 4548f7142ed4SLai Jiangshan mutex_lock(&wq->mutex); 4549a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&wq->dfl_pwq->pool->lock); 45504c16bd32STejun Heo get_pwq(wq->dfl_pwq); 4551a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&wq->dfl_pwq->pool->lock); 4552636b927eSTejun Heo old_pwq = install_unbound_pwq(wq, cpu, wq->dfl_pwq); 45534c16bd32STejun Heo out_unlock: 45544c16bd32STejun Heo mutex_unlock(&wq->mutex); 45554c16bd32STejun Heo put_pwq_unlocked(old_pwq); 45564c16bd32STejun Heo } 45574c16bd32STejun Heo 455830cdf249STejun Heo static int alloc_and_link_pwqs(struct workqueue_struct *wq) 45591da177e4SLinus Torvalds { 456049e3cf44STejun Heo bool highpri = wq->flags & WQ_HIGHPRI; 45618a2b7538STejun Heo int cpu, ret; 4562e1d8aa9fSFrederic Weisbecker 4563687a9aa5STejun Heo wq->cpu_pwq = alloc_percpu(struct pool_workqueue *); 4564ee1ceef7STejun Heo if (!wq->cpu_pwq) 4565687a9aa5STejun Heo goto enomem; 456630cdf249STejun Heo 4567636b927eSTejun Heo if (!(wq->flags & WQ_UNBOUND)) { 456830cdf249STejun Heo for_each_possible_cpu(cpu) { 4569687a9aa5STejun Heo struct pool_workqueue **pwq_p = 4570ee1ceef7STejun Heo per_cpu_ptr(wq->cpu_pwq, cpu); 4571687a9aa5STejun Heo struct worker_pool *pool = 4572687a9aa5STejun Heo &(per_cpu_ptr(cpu_worker_pools, cpu)[highpri]); 457330cdf249STejun Heo 4574687a9aa5STejun Heo *pwq_p = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, 4575687a9aa5STejun Heo pool->node); 4576687a9aa5STejun Heo if (!*pwq_p) 4577687a9aa5STejun Heo goto enomem; 4578687a9aa5STejun Heo 4579687a9aa5STejun Heo init_pwq(*pwq_p, wq, pool); 4580f147f29eSTejun Heo 4581f147f29eSTejun Heo mutex_lock(&wq->mutex); 4582687a9aa5STejun Heo link_pwq(*pwq_p); 4583f147f29eSTejun Heo mutex_unlock(&wq->mutex); 458430cdf249STejun Heo } 458530cdf249STejun Heo return 0; 4586509b3204SDaniel Jordan } 4587509b3204SDaniel Jordan 4588ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 4589509b3204SDaniel Jordan if (wq->flags & __WQ_ORDERED) { 45908a2b7538STejun Heo ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); 45918a2b7538STejun Heo /* there should only be single pwq for ordering guarantee */ 45928a2b7538STejun Heo WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || 45938a2b7538STejun Heo wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), 45948a2b7538STejun Heo "ordering guarantee broken for workqueue %s\n", wq->name); 45959e8cd2f5STejun Heo } else { 4596509b3204SDaniel Jordan ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); 45979e8cd2f5STejun Heo } 4598ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 4599509b3204SDaniel Jordan 460064344553SZqiang /* for unbound pwq, flush the pwq_release_worker ensures that the 460164344553SZqiang * pwq_release_workfn() completes before calling kfree(wq). 460264344553SZqiang */ 460364344553SZqiang if (ret) 460464344553SZqiang kthread_flush_worker(pwq_release_worker); 460564344553SZqiang 4606509b3204SDaniel Jordan return ret; 4607687a9aa5STejun Heo 4608687a9aa5STejun Heo enomem: 4609687a9aa5STejun Heo if (wq->cpu_pwq) { 46107b42f401SZqiang for_each_possible_cpu(cpu) { 46117b42f401SZqiang struct pool_workqueue *pwq = *per_cpu_ptr(wq->cpu_pwq, cpu); 46127b42f401SZqiang 46137b42f401SZqiang if (pwq) 46147b42f401SZqiang kmem_cache_free(pwq_cache, pwq); 46157b42f401SZqiang } 4616687a9aa5STejun Heo free_percpu(wq->cpu_pwq); 4617687a9aa5STejun Heo wq->cpu_pwq = NULL; 4618687a9aa5STejun Heo } 4619687a9aa5STejun Heo return -ENOMEM; 46200f900049STejun Heo } 46210f900049STejun Heo 4622f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 4623f3421797STejun Heo const char *name) 4624b71ab8c2STejun Heo { 4625636b927eSTejun Heo if (max_active < 1 || max_active > WQ_MAX_ACTIVE) 4626044c782cSValentin Ilie pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 4627636b927eSTejun Heo max_active, name, 1, WQ_MAX_ACTIVE); 4628b71ab8c2STejun Heo 4629636b927eSTejun Heo return clamp_val(max_active, 1, WQ_MAX_ACTIVE); 4630b71ab8c2STejun Heo } 4631b71ab8c2STejun Heo 4632983c7515STejun Heo /* 4633983c7515STejun Heo * Workqueues which may be used during memory reclaim should have a rescuer 4634983c7515STejun Heo * to guarantee forward progress. 4635983c7515STejun Heo */ 4636983c7515STejun Heo static int init_rescuer(struct workqueue_struct *wq) 4637983c7515STejun Heo { 4638983c7515STejun Heo struct worker *rescuer; 4639b92b36eaSDan Carpenter int ret; 4640983c7515STejun Heo 4641983c7515STejun Heo if (!(wq->flags & WQ_MEM_RECLAIM)) 4642983c7515STejun Heo return 0; 4643983c7515STejun Heo 4644983c7515STejun Heo rescuer = alloc_worker(NUMA_NO_NODE); 46454c0736a7SPetr Mladek if (!rescuer) { 46464c0736a7SPetr Mladek pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n", 46474c0736a7SPetr Mladek wq->name); 4648983c7515STejun Heo return -ENOMEM; 46494c0736a7SPetr Mladek } 4650983c7515STejun Heo 4651983c7515STejun Heo rescuer->rescue_wq = wq; 4652b6a46f72SAaron Tomlin rescuer->task = kthread_create(rescuer_thread, rescuer, "kworker/R-%s", wq->name); 4653f187b697SSean Fu if (IS_ERR(rescuer->task)) { 4654b92b36eaSDan Carpenter ret = PTR_ERR(rescuer->task); 46554c0736a7SPetr Mladek pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe", 46564c0736a7SPetr Mladek wq->name, ERR_PTR(ret)); 4657983c7515STejun Heo kfree(rescuer); 4658b92b36eaSDan Carpenter return ret; 4659983c7515STejun Heo } 4660983c7515STejun Heo 4661983c7515STejun Heo wq->rescuer = rescuer; 4662983c7515STejun Heo kthread_bind_mask(rescuer->task, cpu_possible_mask); 4663983c7515STejun Heo wake_up_process(rescuer->task); 4664983c7515STejun Heo 4665983c7515STejun Heo return 0; 4666983c7515STejun Heo } 4667983c7515STejun Heo 4668a2775bbcSMathieu Malaterre __printf(1, 4) 4669669de8bdSBart Van Assche struct workqueue_struct *alloc_workqueue(const char *fmt, 467097e37d7bSTejun Heo unsigned int flags, 4671669de8bdSBart Van Assche int max_active, ...) 46723af24433SOleg Nesterov { 4673ecf6881fSTejun Heo va_list args; 46743af24433SOleg Nesterov struct workqueue_struct *wq; 467549e3cf44STejun Heo struct pool_workqueue *pwq; 4676b196be89STejun Heo 46775c0338c6STejun Heo /* 4678fef59c9cSTejun Heo * Unbound && max_active == 1 used to imply ordered, which is no longer 4679fef59c9cSTejun Heo * the case on many machines due to per-pod pools. While 46805c0338c6STejun Heo * alloc_ordered_workqueue() is the right way to create an ordered 4681fef59c9cSTejun Heo * workqueue, keep the previous behavior to avoid subtle breakages. 46825c0338c6STejun Heo */ 46835c0338c6STejun Heo if ((flags & WQ_UNBOUND) && max_active == 1) 46845c0338c6STejun Heo flags |= __WQ_ORDERED; 46855c0338c6STejun Heo 4686cee22a15SViresh Kumar /* see the comment above the definition of WQ_POWER_EFFICIENT */ 4687cee22a15SViresh Kumar if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) 4688cee22a15SViresh Kumar flags |= WQ_UNBOUND; 4689cee22a15SViresh Kumar 4690ecf6881fSTejun Heo /* allocate wq and format name */ 4691636b927eSTejun Heo wq = kzalloc(sizeof(*wq), GFP_KERNEL); 4692b196be89STejun Heo if (!wq) 4693d2c1d404STejun Heo return NULL; 4694b196be89STejun Heo 46956029a918STejun Heo if (flags & WQ_UNBOUND) { 4696be69d00dSThomas Gleixner wq->unbound_attrs = alloc_workqueue_attrs(); 46976029a918STejun Heo if (!wq->unbound_attrs) 46986029a918STejun Heo goto err_free_wq; 46996029a918STejun Heo } 47006029a918STejun Heo 4701669de8bdSBart Van Assche va_start(args, max_active); 4702ecf6881fSTejun Heo vsnprintf(wq->name, sizeof(wq->name), fmt, args); 4703b196be89STejun Heo va_end(args); 47043af24433SOleg Nesterov 4705d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 4706b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 47073af24433SOleg Nesterov 4708b196be89STejun Heo /* init wq */ 470997e37d7bSTejun Heo wq->flags = flags; 4710a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 47113c25a55dSLai Jiangshan mutex_init(&wq->mutex); 4712112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 0); 471330cdf249STejun Heo INIT_LIST_HEAD(&wq->pwqs); 471473f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 471573f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 4716493a1724STejun Heo INIT_LIST_HEAD(&wq->maydays); 47173af24433SOleg Nesterov 4718669de8bdSBart Van Assche wq_init_lockdep(wq); 4719cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 47203af24433SOleg Nesterov 472130cdf249STejun Heo if (alloc_and_link_pwqs(wq) < 0) 472282efcab3SBart Van Assche goto err_unreg_lockdep; 47231537663fSTejun Heo 472440c17f75STejun Heo if (wq_online && init_rescuer(wq) < 0) 4725d2c1d404STejun Heo goto err_destroy; 4726e22bee78STejun Heo 4727226223abSTejun Heo if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) 4728226223abSTejun Heo goto err_destroy; 4729226223abSTejun Heo 47306af8bf3dSOleg Nesterov /* 473168e13a67SLai Jiangshan * wq_pool_mutex protects global freeze state and workqueues list. 473268e13a67SLai Jiangshan * Grab it, adjust max_active and add the new @wq to workqueues 473368e13a67SLai Jiangshan * list. 47346af8bf3dSOleg Nesterov */ 473568e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4736a0a1a5fdSTejun Heo 4737a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 473849e3cf44STejun Heo for_each_pwq(pwq, wq) 4739699ce097STejun Heo pwq_adjust_max_active(pwq); 4740a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4741a0a1a5fdSTejun Heo 4742e2dca7adSTejun Heo list_add_tail_rcu(&wq->list, &workqueues); 4743a0a1a5fdSTejun Heo 474468e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 47453af24433SOleg Nesterov 47463af24433SOleg Nesterov return wq; 4747d2c1d404STejun Heo 474882efcab3SBart Van Assche err_unreg_lockdep: 4749009bb421SBart Van Assche wq_unregister_lockdep(wq); 4750009bb421SBart Van Assche wq_free_lockdep(wq); 475182efcab3SBart Van Assche err_free_wq: 47526029a918STejun Heo free_workqueue_attrs(wq->unbound_attrs); 47534690c4abSTejun Heo kfree(wq); 4754d2c1d404STejun Heo return NULL; 4755d2c1d404STejun Heo err_destroy: 4756d2c1d404STejun Heo destroy_workqueue(wq); 47574690c4abSTejun Heo return NULL; 47581da177e4SLinus Torvalds } 4759669de8bdSBart Van Assche EXPORT_SYMBOL_GPL(alloc_workqueue); 47601da177e4SLinus Torvalds 4761c29eb853STejun Heo static bool pwq_busy(struct pool_workqueue *pwq) 4762c29eb853STejun Heo { 4763c29eb853STejun Heo int i; 4764c29eb853STejun Heo 4765c29eb853STejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 4766c29eb853STejun Heo if (pwq->nr_in_flight[i]) 4767c29eb853STejun Heo return true; 4768c29eb853STejun Heo 4769c29eb853STejun Heo if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1)) 4770c29eb853STejun Heo return true; 4771f97a4a1aSLai Jiangshan if (pwq->nr_active || !list_empty(&pwq->inactive_works)) 4772c29eb853STejun Heo return true; 4773c29eb853STejun Heo 4774c29eb853STejun Heo return false; 4775c29eb853STejun Heo } 4776c29eb853STejun Heo 47773af24433SOleg Nesterov /** 47783af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 47793af24433SOleg Nesterov * @wq: target workqueue 47803af24433SOleg Nesterov * 47813af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 47823af24433SOleg Nesterov */ 47833af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 47843af24433SOleg Nesterov { 478549e3cf44STejun Heo struct pool_workqueue *pwq; 4786636b927eSTejun Heo int cpu; 47873af24433SOleg Nesterov 4788def98c84STejun Heo /* 4789def98c84STejun Heo * Remove it from sysfs first so that sanity check failure doesn't 4790def98c84STejun Heo * lead to sysfs name conflicts. 4791def98c84STejun Heo */ 4792def98c84STejun Heo workqueue_sysfs_unregister(wq); 4793def98c84STejun Heo 479433e3f0a3SRichard Clark /* mark the workqueue destruction is in progress */ 479533e3f0a3SRichard Clark mutex_lock(&wq->mutex); 479633e3f0a3SRichard Clark wq->flags |= __WQ_DESTROYING; 479733e3f0a3SRichard Clark mutex_unlock(&wq->mutex); 479833e3f0a3SRichard Clark 47999c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 48009c5a2ba7STejun Heo drain_workqueue(wq); 4801c8efcc25STejun Heo 4802def98c84STejun Heo /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ 4803def98c84STejun Heo if (wq->rescuer) { 4804def98c84STejun Heo struct worker *rescuer = wq->rescuer; 4805def98c84STejun Heo 4806def98c84STejun Heo /* this prevents new queueing */ 4807a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&wq_mayday_lock); 4808def98c84STejun Heo wq->rescuer = NULL; 4809a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&wq_mayday_lock); 4810def98c84STejun Heo 4811def98c84STejun Heo /* rescuer will empty maydays list before exiting */ 4812def98c84STejun Heo kthread_stop(rescuer->task); 48138efe1223STejun Heo kfree(rescuer); 4814def98c84STejun Heo } 4815def98c84STejun Heo 4816c29eb853STejun Heo /* 4817c29eb853STejun Heo * Sanity checks - grab all the locks so that we wait for all 4818c29eb853STejun Heo * in-flight operations which may do put_pwq(). 4819c29eb853STejun Heo */ 4820c29eb853STejun Heo mutex_lock(&wq_pool_mutex); 4821b09f4fd3SLai Jiangshan mutex_lock(&wq->mutex); 482249e3cf44STejun Heo for_each_pwq(pwq, wq) { 4823a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pwq->pool->lock); 4824c29eb853STejun Heo if (WARN_ON(pwq_busy(pwq))) { 48251d9a6159SKefeng Wang pr_warn("%s: %s has the following busy pwq\n", 4826e66b39afSTejun Heo __func__, wq->name); 4827c29eb853STejun Heo show_pwq(pwq); 4828a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pwq->pool->lock); 4829b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 4830c29eb853STejun Heo mutex_unlock(&wq_pool_mutex); 483155df0933SImran Khan show_one_workqueue(wq); 48326183c009STejun Heo return; 483376af4d93STejun Heo } 4834a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pwq->pool->lock); 483576af4d93STejun Heo } 4836b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 48376183c009STejun Heo 4838a0a1a5fdSTejun Heo /* 4839a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 4840a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 4841a0a1a5fdSTejun Heo */ 4842e2dca7adSTejun Heo list_del_rcu(&wq->list); 484368e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 48443af24433SOleg Nesterov 48458864b4e5STejun Heo /* 4846636b927eSTejun Heo * We're the sole accessor of @wq. Directly access cpu_pwq and dfl_pwq 4847636b927eSTejun Heo * to put the base refs. @wq will be auto-destroyed from the last 4848636b927eSTejun Heo * pwq_put. RCU read lock prevents @wq from going away from under us. 48498864b4e5STejun Heo */ 4850636b927eSTejun Heo rcu_read_lock(); 4851636b927eSTejun Heo 4852636b927eSTejun Heo for_each_possible_cpu(cpu) { 4853636b927eSTejun Heo pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu)); 4854636b927eSTejun Heo RCU_INIT_POINTER(*per_cpu_ptr(wq->cpu_pwq, cpu), NULL); 48554c16bd32STejun Heo put_pwq_unlocked(pwq); 48564c16bd32STejun Heo } 48574c16bd32STejun Heo 4858636b927eSTejun Heo put_pwq_unlocked(wq->dfl_pwq); 48594c16bd32STejun Heo wq->dfl_pwq = NULL; 4860636b927eSTejun Heo 4861636b927eSTejun Heo rcu_read_unlock(); 48623af24433SOleg Nesterov } 48633af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 48643af24433SOleg Nesterov 4865dcd989cbSTejun Heo /** 4866dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 4867dcd989cbSTejun Heo * @wq: target workqueue 4868dcd989cbSTejun Heo * @max_active: new max_active value. 4869dcd989cbSTejun Heo * 4870dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 4871dcd989cbSTejun Heo * 4872dcd989cbSTejun Heo * CONTEXT: 4873dcd989cbSTejun Heo * Don't call from IRQ context. 4874dcd989cbSTejun Heo */ 4875dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 4876dcd989cbSTejun Heo { 487749e3cf44STejun Heo struct pool_workqueue *pwq; 4878dcd989cbSTejun Heo 48798719dceaSTejun Heo /* disallow meddling with max_active for ordered workqueues */ 48800a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 48818719dceaSTejun Heo return; 48828719dceaSTejun Heo 4883f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 4884dcd989cbSTejun Heo 4885a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 4886dcd989cbSTejun Heo 48870a94efb5STejun Heo wq->flags &= ~__WQ_ORDERED; 4888dcd989cbSTejun Heo wq->saved_max_active = max_active; 4889dcd989cbSTejun Heo 4890699ce097STejun Heo for_each_pwq(pwq, wq) 4891699ce097STejun Heo pwq_adjust_max_active(pwq); 4892dcd989cbSTejun Heo 4893a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4894dcd989cbSTejun Heo } 4895dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 4896dcd989cbSTejun Heo 4897dcd989cbSTejun Heo /** 489827d4ee03SLukas Wunner * current_work - retrieve %current task's work struct 489927d4ee03SLukas Wunner * 490027d4ee03SLukas Wunner * Determine if %current task is a workqueue worker and what it's working on. 490127d4ee03SLukas Wunner * Useful to find out the context that the %current task is running in. 490227d4ee03SLukas Wunner * 490327d4ee03SLukas Wunner * Return: work struct if %current task is a workqueue worker, %NULL otherwise. 490427d4ee03SLukas Wunner */ 490527d4ee03SLukas Wunner struct work_struct *current_work(void) 490627d4ee03SLukas Wunner { 490727d4ee03SLukas Wunner struct worker *worker = current_wq_worker(); 490827d4ee03SLukas Wunner 490927d4ee03SLukas Wunner return worker ? worker->current_work : NULL; 491027d4ee03SLukas Wunner } 491127d4ee03SLukas Wunner EXPORT_SYMBOL(current_work); 491227d4ee03SLukas Wunner 491327d4ee03SLukas Wunner /** 4914e6267616STejun Heo * current_is_workqueue_rescuer - is %current workqueue rescuer? 4915e6267616STejun Heo * 4916e6267616STejun Heo * Determine whether %current is a workqueue rescuer. Can be used from 4917e6267616STejun Heo * work functions to determine whether it's being run off the rescuer task. 4918d185af30SYacine Belkadi * 4919d185af30SYacine Belkadi * Return: %true if %current is a workqueue rescuer. %false otherwise. 4920e6267616STejun Heo */ 4921e6267616STejun Heo bool current_is_workqueue_rescuer(void) 4922e6267616STejun Heo { 4923e6267616STejun Heo struct worker *worker = current_wq_worker(); 4924e6267616STejun Heo 49256a092dfdSLai Jiangshan return worker && worker->rescue_wq; 4926e6267616STejun Heo } 4927e6267616STejun Heo 4928e6267616STejun Heo /** 4929dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 4930dcd989cbSTejun Heo * @cpu: CPU in question 4931dcd989cbSTejun Heo * @wq: target workqueue 4932dcd989cbSTejun Heo * 4933dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 4934dcd989cbSTejun Heo * no synchronization around this function and the test result is 4935dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 4936dcd989cbSTejun Heo * 4937d3251859STejun Heo * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. 4938636b927eSTejun Heo * 4939636b927eSTejun Heo * With the exception of ordered workqueues, all workqueues have per-cpu 4940636b927eSTejun Heo * pool_workqueues, each with its own congested state. A workqueue being 4941636b927eSTejun Heo * congested on one CPU doesn't mean that the workqueue is contested on any 4942636b927eSTejun Heo * other CPUs. 4943d3251859STejun Heo * 4944d185af30SYacine Belkadi * Return: 4945dcd989cbSTejun Heo * %true if congested, %false otherwise. 4946dcd989cbSTejun Heo */ 4947d84ff051STejun Heo bool workqueue_congested(int cpu, struct workqueue_struct *wq) 4948dcd989cbSTejun Heo { 49497fb98ea7STejun Heo struct pool_workqueue *pwq; 495076af4d93STejun Heo bool ret; 495176af4d93STejun Heo 495224acfb71SThomas Gleixner rcu_read_lock(); 495324acfb71SThomas Gleixner preempt_disable(); 49547fb98ea7STejun Heo 4955d3251859STejun Heo if (cpu == WORK_CPU_UNBOUND) 4956d3251859STejun Heo cpu = smp_processor_id(); 4957d3251859STejun Heo 4958687a9aa5STejun Heo pwq = *per_cpu_ptr(wq->cpu_pwq, cpu); 4959f97a4a1aSLai Jiangshan ret = !list_empty(&pwq->inactive_works); 4960636b927eSTejun Heo 496124acfb71SThomas Gleixner preempt_enable(); 496224acfb71SThomas Gleixner rcu_read_unlock(); 496376af4d93STejun Heo 496476af4d93STejun Heo return ret; 4965dcd989cbSTejun Heo } 4966dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 4967dcd989cbSTejun Heo 4968dcd989cbSTejun Heo /** 4969dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 4970dcd989cbSTejun Heo * @work: the work to be tested 4971dcd989cbSTejun Heo * 4972dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 4973dcd989cbSTejun Heo * synchronization around this function and the test result is 4974dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 4975dcd989cbSTejun Heo * 4976d185af30SYacine Belkadi * Return: 4977dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 4978dcd989cbSTejun Heo */ 4979dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 4980dcd989cbSTejun Heo { 4981fa1b54e6STejun Heo struct worker_pool *pool; 4982dcd989cbSTejun Heo unsigned long flags; 4983dcd989cbSTejun Heo unsigned int ret = 0; 4984dcd989cbSTejun Heo 4985dcd989cbSTejun Heo if (work_pending(work)) 4986dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 4987038366c5SLai Jiangshan 498824acfb71SThomas Gleixner rcu_read_lock(); 4989fa1b54e6STejun Heo pool = get_work_pool(work); 4990038366c5SLai Jiangshan if (pool) { 4991a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irqsave(&pool->lock, flags); 4992c9e7cf27STejun Heo if (find_worker_executing_work(pool, work)) 4993dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 4994a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irqrestore(&pool->lock, flags); 4995038366c5SLai Jiangshan } 499624acfb71SThomas Gleixner rcu_read_unlock(); 4997dcd989cbSTejun Heo 4998dcd989cbSTejun Heo return ret; 4999dcd989cbSTejun Heo } 5000dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 5001dcd989cbSTejun Heo 50023d1cb205STejun Heo /** 50033d1cb205STejun Heo * set_worker_desc - set description for the current work item 50043d1cb205STejun Heo * @fmt: printf-style format string 50053d1cb205STejun Heo * @...: arguments for the format string 50063d1cb205STejun Heo * 50073d1cb205STejun Heo * This function can be called by a running work function to describe what 50083d1cb205STejun Heo * the work item is about. If the worker task gets dumped, this 50093d1cb205STejun Heo * information will be printed out together to help debugging. The 50103d1cb205STejun Heo * description can be at most WORKER_DESC_LEN including the trailing '\0'. 50113d1cb205STejun Heo */ 50123d1cb205STejun Heo void set_worker_desc(const char *fmt, ...) 50133d1cb205STejun Heo { 50143d1cb205STejun Heo struct worker *worker = current_wq_worker(); 50153d1cb205STejun Heo va_list args; 50163d1cb205STejun Heo 50173d1cb205STejun Heo if (worker) { 50183d1cb205STejun Heo va_start(args, fmt); 50193d1cb205STejun Heo vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); 50203d1cb205STejun Heo va_end(args); 50213d1cb205STejun Heo } 50223d1cb205STejun Heo } 50235c750d58SSteffen Maier EXPORT_SYMBOL_GPL(set_worker_desc); 50243d1cb205STejun Heo 50253d1cb205STejun Heo /** 50263d1cb205STejun Heo * print_worker_info - print out worker information and description 50273d1cb205STejun Heo * @log_lvl: the log level to use when printing 50283d1cb205STejun Heo * @task: target task 50293d1cb205STejun Heo * 50303d1cb205STejun Heo * If @task is a worker and currently executing a work item, print out the 50313d1cb205STejun Heo * name of the workqueue being serviced and worker description set with 50323d1cb205STejun Heo * set_worker_desc() by the currently executing work item. 50333d1cb205STejun Heo * 50343d1cb205STejun Heo * This function can be safely called on any task as long as the 50353d1cb205STejun Heo * task_struct itself is accessible. While safe, this function isn't 50363d1cb205STejun Heo * synchronized and may print out mixups or garbages of limited length. 50373d1cb205STejun Heo */ 50383d1cb205STejun Heo void print_worker_info(const char *log_lvl, struct task_struct *task) 50393d1cb205STejun Heo { 50403d1cb205STejun Heo work_func_t *fn = NULL; 50413d1cb205STejun Heo char name[WQ_NAME_LEN] = { }; 50423d1cb205STejun Heo char desc[WORKER_DESC_LEN] = { }; 50433d1cb205STejun Heo struct pool_workqueue *pwq = NULL; 50443d1cb205STejun Heo struct workqueue_struct *wq = NULL; 50453d1cb205STejun Heo struct worker *worker; 50463d1cb205STejun Heo 50473d1cb205STejun Heo if (!(task->flags & PF_WQ_WORKER)) 50483d1cb205STejun Heo return; 50493d1cb205STejun Heo 50503d1cb205STejun Heo /* 50513d1cb205STejun Heo * This function is called without any synchronization and @task 50523d1cb205STejun Heo * could be in any state. Be careful with dereferences. 50533d1cb205STejun Heo */ 5054e700591aSPetr Mladek worker = kthread_probe_data(task); 50553d1cb205STejun Heo 50563d1cb205STejun Heo /* 50578bf89593STejun Heo * Carefully copy the associated workqueue's workfn, name and desc. 50588bf89593STejun Heo * Keep the original last '\0' in case the original is garbage. 50593d1cb205STejun Heo */ 5060fe557319SChristoph Hellwig copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn)); 5061fe557319SChristoph Hellwig copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq)); 5062fe557319SChristoph Hellwig copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq)); 5063fe557319SChristoph Hellwig copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1); 5064fe557319SChristoph Hellwig copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1); 50653d1cb205STejun Heo 50663d1cb205STejun Heo if (fn || name[0] || desc[0]) { 5067d75f773cSSakari Ailus printk("%sWorkqueue: %s %ps", log_lvl, name, fn); 50688bf89593STejun Heo if (strcmp(name, desc)) 50693d1cb205STejun Heo pr_cont(" (%s)", desc); 50703d1cb205STejun Heo pr_cont("\n"); 50713d1cb205STejun Heo } 50723d1cb205STejun Heo } 50733d1cb205STejun Heo 50743494fc30STejun Heo static void pr_cont_pool_info(struct worker_pool *pool) 50753494fc30STejun Heo { 50763494fc30STejun Heo pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask); 50773494fc30STejun Heo if (pool->node != NUMA_NO_NODE) 50783494fc30STejun Heo pr_cont(" node=%d", pool->node); 50793494fc30STejun Heo pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice); 50803494fc30STejun Heo } 50813494fc30STejun Heo 5082c76feb0dSPaul E. McKenney struct pr_cont_work_struct { 5083c76feb0dSPaul E. McKenney bool comma; 5084c76feb0dSPaul E. McKenney work_func_t func; 5085c76feb0dSPaul E. McKenney long ctr; 5086c76feb0dSPaul E. McKenney }; 5087c76feb0dSPaul E. McKenney 5088c76feb0dSPaul E. McKenney static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp) 5089c76feb0dSPaul E. McKenney { 5090c76feb0dSPaul E. McKenney if (!pcwsp->ctr) 5091c76feb0dSPaul E. McKenney goto out_record; 5092c76feb0dSPaul E. McKenney if (func == pcwsp->func) { 5093c76feb0dSPaul E. McKenney pcwsp->ctr++; 5094c76feb0dSPaul E. McKenney return; 5095c76feb0dSPaul E. McKenney } 5096c76feb0dSPaul E. McKenney if (pcwsp->ctr == 1) 5097c76feb0dSPaul E. McKenney pr_cont("%s %ps", pcwsp->comma ? "," : "", pcwsp->func); 5098c76feb0dSPaul E. McKenney else 5099c76feb0dSPaul E. McKenney pr_cont("%s %ld*%ps", pcwsp->comma ? "," : "", pcwsp->ctr, pcwsp->func); 5100c76feb0dSPaul E. McKenney pcwsp->ctr = 0; 5101c76feb0dSPaul E. McKenney out_record: 5102c76feb0dSPaul E. McKenney if ((long)func == -1L) 5103c76feb0dSPaul E. McKenney return; 5104c76feb0dSPaul E. McKenney pcwsp->comma = comma; 5105c76feb0dSPaul E. McKenney pcwsp->func = func; 5106c76feb0dSPaul E. McKenney pcwsp->ctr = 1; 5107c76feb0dSPaul E. McKenney } 5108c76feb0dSPaul E. McKenney 5109c76feb0dSPaul E. McKenney static void pr_cont_work(bool comma, struct work_struct *work, struct pr_cont_work_struct *pcwsp) 51103494fc30STejun Heo { 51113494fc30STejun Heo if (work->func == wq_barrier_func) { 51123494fc30STejun Heo struct wq_barrier *barr; 51133494fc30STejun Heo 51143494fc30STejun Heo barr = container_of(work, struct wq_barrier, work); 51153494fc30STejun Heo 5116c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); 51173494fc30STejun Heo pr_cont("%s BAR(%d)", comma ? "," : "", 51183494fc30STejun Heo task_pid_nr(barr->task)); 51193494fc30STejun Heo } else { 5120c76feb0dSPaul E. McKenney if (!comma) 5121c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); 5122c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, work->func, pcwsp); 51233494fc30STejun Heo } 51243494fc30STejun Heo } 51253494fc30STejun Heo 51263494fc30STejun Heo static void show_pwq(struct pool_workqueue *pwq) 51273494fc30STejun Heo { 5128c76feb0dSPaul E. McKenney struct pr_cont_work_struct pcws = { .ctr = 0, }; 51293494fc30STejun Heo struct worker_pool *pool = pwq->pool; 51303494fc30STejun Heo struct work_struct *work; 51313494fc30STejun Heo struct worker *worker; 51323494fc30STejun Heo bool has_in_flight = false, has_pending = false; 51333494fc30STejun Heo int bkt; 51343494fc30STejun Heo 51353494fc30STejun Heo pr_info(" pwq %d:", pool->id); 51363494fc30STejun Heo pr_cont_pool_info(pool); 51373494fc30STejun Heo 5138e66b39afSTejun Heo pr_cont(" active=%d/%d refcnt=%d%s\n", 5139e66b39afSTejun Heo pwq->nr_active, pwq->max_active, pwq->refcnt, 51403494fc30STejun Heo !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); 51413494fc30STejun Heo 51423494fc30STejun Heo hash_for_each(pool->busy_hash, bkt, worker, hentry) { 51433494fc30STejun Heo if (worker->current_pwq == pwq) { 51443494fc30STejun Heo has_in_flight = true; 51453494fc30STejun Heo break; 51463494fc30STejun Heo } 51473494fc30STejun Heo } 51483494fc30STejun Heo if (has_in_flight) { 51493494fc30STejun Heo bool comma = false; 51503494fc30STejun Heo 51513494fc30STejun Heo pr_info(" in-flight:"); 51523494fc30STejun Heo hash_for_each(pool->busy_hash, bkt, worker, hentry) { 51533494fc30STejun Heo if (worker->current_pwq != pwq) 51543494fc30STejun Heo continue; 51553494fc30STejun Heo 5156d75f773cSSakari Ailus pr_cont("%s %d%s:%ps", comma ? "," : "", 51573494fc30STejun Heo task_pid_nr(worker->task), 515830ae2fc0STejun Heo worker->rescue_wq ? "(RESCUER)" : "", 51593494fc30STejun Heo worker->current_func); 51603494fc30STejun Heo list_for_each_entry(work, &worker->scheduled, entry) 5161c76feb0dSPaul E. McKenney pr_cont_work(false, work, &pcws); 5162c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 51633494fc30STejun Heo comma = true; 51643494fc30STejun Heo } 51653494fc30STejun Heo pr_cont("\n"); 51663494fc30STejun Heo } 51673494fc30STejun Heo 51683494fc30STejun Heo list_for_each_entry(work, &pool->worklist, entry) { 51693494fc30STejun Heo if (get_work_pwq(work) == pwq) { 51703494fc30STejun Heo has_pending = true; 51713494fc30STejun Heo break; 51723494fc30STejun Heo } 51733494fc30STejun Heo } 51743494fc30STejun Heo if (has_pending) { 51753494fc30STejun Heo bool comma = false; 51763494fc30STejun Heo 51773494fc30STejun Heo pr_info(" pending:"); 51783494fc30STejun Heo list_for_each_entry(work, &pool->worklist, entry) { 51793494fc30STejun Heo if (get_work_pwq(work) != pwq) 51803494fc30STejun Heo continue; 51813494fc30STejun Heo 5182c76feb0dSPaul E. McKenney pr_cont_work(comma, work, &pcws); 51833494fc30STejun Heo comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); 51843494fc30STejun Heo } 5185c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 51863494fc30STejun Heo pr_cont("\n"); 51873494fc30STejun Heo } 51883494fc30STejun Heo 5189f97a4a1aSLai Jiangshan if (!list_empty(&pwq->inactive_works)) { 51903494fc30STejun Heo bool comma = false; 51913494fc30STejun Heo 5192f97a4a1aSLai Jiangshan pr_info(" inactive:"); 5193f97a4a1aSLai Jiangshan list_for_each_entry(work, &pwq->inactive_works, entry) { 5194c76feb0dSPaul E. McKenney pr_cont_work(comma, work, &pcws); 51953494fc30STejun Heo comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); 51963494fc30STejun Heo } 5197c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 51983494fc30STejun Heo pr_cont("\n"); 51993494fc30STejun Heo } 52003494fc30STejun Heo } 52013494fc30STejun Heo 52023494fc30STejun Heo /** 520355df0933SImran Khan * show_one_workqueue - dump state of specified workqueue 520455df0933SImran Khan * @wq: workqueue whose state will be printed 52053494fc30STejun Heo */ 520655df0933SImran Khan void show_one_workqueue(struct workqueue_struct *wq) 52073494fc30STejun Heo { 52083494fc30STejun Heo struct pool_workqueue *pwq; 52093494fc30STejun Heo bool idle = true; 521055df0933SImran Khan unsigned long flags; 52113494fc30STejun Heo 52123494fc30STejun Heo for_each_pwq(pwq, wq) { 5213f97a4a1aSLai Jiangshan if (pwq->nr_active || !list_empty(&pwq->inactive_works)) { 52143494fc30STejun Heo idle = false; 52153494fc30STejun Heo break; 52163494fc30STejun Heo } 52173494fc30STejun Heo } 521855df0933SImran Khan if (idle) /* Nothing to print for idle workqueue */ 521955df0933SImran Khan return; 52203494fc30STejun Heo 52213494fc30STejun Heo pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags); 52223494fc30STejun Heo 52233494fc30STejun Heo for_each_pwq(pwq, wq) { 5224a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irqsave(&pwq->pool->lock, flags); 522557116ce1SJohan Hovold if (pwq->nr_active || !list_empty(&pwq->inactive_works)) { 522657116ce1SJohan Hovold /* 522757116ce1SJohan Hovold * Defer printing to avoid deadlocks in console 522857116ce1SJohan Hovold * drivers that queue work while holding locks 522957116ce1SJohan Hovold * also taken in their write paths. 523057116ce1SJohan Hovold */ 523157116ce1SJohan Hovold printk_deferred_enter(); 52323494fc30STejun Heo show_pwq(pwq); 523357116ce1SJohan Hovold printk_deferred_exit(); 523457116ce1SJohan Hovold } 5235a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); 523662635ea8SSergey Senozhatsky /* 523762635ea8SSergey Senozhatsky * We could be printing a lot from atomic context, e.g. 523855df0933SImran Khan * sysrq-t -> show_all_workqueues(). Avoid triggering 523962635ea8SSergey Senozhatsky * hard lockup. 524062635ea8SSergey Senozhatsky */ 524162635ea8SSergey Senozhatsky touch_nmi_watchdog(); 52423494fc30STejun Heo } 524355df0933SImran Khan 52443494fc30STejun Heo } 52453494fc30STejun Heo 524655df0933SImran Khan /** 524755df0933SImran Khan * show_one_worker_pool - dump state of specified worker pool 524855df0933SImran Khan * @pool: worker pool whose state will be printed 524955df0933SImran Khan */ 525055df0933SImran Khan static void show_one_worker_pool(struct worker_pool *pool) 525155df0933SImran Khan { 52523494fc30STejun Heo struct worker *worker; 52533494fc30STejun Heo bool first = true; 525455df0933SImran Khan unsigned long flags; 5255335a42ebSPetr Mladek unsigned long hung = 0; 52563494fc30STejun Heo 5257a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irqsave(&pool->lock, flags); 52583494fc30STejun Heo if (pool->nr_workers == pool->nr_idle) 52593494fc30STejun Heo goto next_pool; 5260335a42ebSPetr Mladek 5261335a42ebSPetr Mladek /* How long the first pending work is waiting for a worker. */ 5262335a42ebSPetr Mladek if (!list_empty(&pool->worklist)) 5263335a42ebSPetr Mladek hung = jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000; 5264335a42ebSPetr Mladek 526557116ce1SJohan Hovold /* 526657116ce1SJohan Hovold * Defer printing to avoid deadlocks in console drivers that 526757116ce1SJohan Hovold * queue work while holding locks also taken in their write 526857116ce1SJohan Hovold * paths. 526957116ce1SJohan Hovold */ 527057116ce1SJohan Hovold printk_deferred_enter(); 52713494fc30STejun Heo pr_info("pool %d:", pool->id); 52723494fc30STejun Heo pr_cont_pool_info(pool); 5273335a42ebSPetr Mladek pr_cont(" hung=%lus workers=%d", hung, pool->nr_workers); 52743494fc30STejun Heo if (pool->manager) 52753494fc30STejun Heo pr_cont(" manager: %d", 52763494fc30STejun Heo task_pid_nr(pool->manager->task)); 52773494fc30STejun Heo list_for_each_entry(worker, &pool->idle_list, entry) { 52783494fc30STejun Heo pr_cont(" %s%d", first ? "idle: " : "", 52793494fc30STejun Heo task_pid_nr(worker->task)); 52803494fc30STejun Heo first = false; 52813494fc30STejun Heo } 52823494fc30STejun Heo pr_cont("\n"); 528357116ce1SJohan Hovold printk_deferred_exit(); 52843494fc30STejun Heo next_pool: 5285a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irqrestore(&pool->lock, flags); 528662635ea8SSergey Senozhatsky /* 528762635ea8SSergey Senozhatsky * We could be printing a lot from atomic context, e.g. 528855df0933SImran Khan * sysrq-t -> show_all_workqueues(). Avoid triggering 528962635ea8SSergey Senozhatsky * hard lockup. 529062635ea8SSergey Senozhatsky */ 529162635ea8SSergey Senozhatsky touch_nmi_watchdog(); 529255df0933SImran Khan 52933494fc30STejun Heo } 52943494fc30STejun Heo 529555df0933SImran Khan /** 529655df0933SImran Khan * show_all_workqueues - dump workqueue state 529755df0933SImran Khan * 5298704bc669SJungseung Lee * Called from a sysrq handler and prints out all busy workqueues and pools. 529955df0933SImran Khan */ 530055df0933SImran Khan void show_all_workqueues(void) 530155df0933SImran Khan { 530255df0933SImran Khan struct workqueue_struct *wq; 530355df0933SImran Khan struct worker_pool *pool; 530455df0933SImran Khan int pi; 530555df0933SImran Khan 530655df0933SImran Khan rcu_read_lock(); 530755df0933SImran Khan 530855df0933SImran Khan pr_info("Showing busy workqueues and worker pools:\n"); 530955df0933SImran Khan 531055df0933SImran Khan list_for_each_entry_rcu(wq, &workqueues, list) 531155df0933SImran Khan show_one_workqueue(wq); 531255df0933SImran Khan 531355df0933SImran Khan for_each_pool(pool, pi) 531455df0933SImran Khan show_one_worker_pool(pool); 531555df0933SImran Khan 531624acfb71SThomas Gleixner rcu_read_unlock(); 53173494fc30STejun Heo } 53183494fc30STejun Heo 5319704bc669SJungseung Lee /** 5320704bc669SJungseung Lee * show_freezable_workqueues - dump freezable workqueue state 5321704bc669SJungseung Lee * 5322704bc669SJungseung Lee * Called from try_to_freeze_tasks() and prints out all freezable workqueues 5323704bc669SJungseung Lee * still busy. 5324704bc669SJungseung Lee */ 5325704bc669SJungseung Lee void show_freezable_workqueues(void) 5326704bc669SJungseung Lee { 5327704bc669SJungseung Lee struct workqueue_struct *wq; 5328704bc669SJungseung Lee 5329704bc669SJungseung Lee rcu_read_lock(); 5330704bc669SJungseung Lee 5331704bc669SJungseung Lee pr_info("Showing freezable workqueues that are still busy:\n"); 5332704bc669SJungseung Lee 5333704bc669SJungseung Lee list_for_each_entry_rcu(wq, &workqueues, list) { 5334704bc669SJungseung Lee if (!(wq->flags & WQ_FREEZABLE)) 5335704bc669SJungseung Lee continue; 5336704bc669SJungseung Lee show_one_workqueue(wq); 5337704bc669SJungseung Lee } 5338704bc669SJungseung Lee 5339704bc669SJungseung Lee rcu_read_unlock(); 5340704bc669SJungseung Lee } 5341704bc669SJungseung Lee 53426b59808bSTejun Heo /* used to show worker information through /proc/PID/{comm,stat,status} */ 53436b59808bSTejun Heo void wq_worker_comm(char *buf, size_t size, struct task_struct *task) 53446b59808bSTejun Heo { 53456b59808bSTejun Heo int off; 53466b59808bSTejun Heo 53476b59808bSTejun Heo /* always show the actual comm */ 53486b59808bSTejun Heo off = strscpy(buf, task->comm, size); 53496b59808bSTejun Heo if (off < 0) 53506b59808bSTejun Heo return; 53516b59808bSTejun Heo 5352197f6accSTejun Heo /* stabilize PF_WQ_WORKER and worker pool association */ 53536b59808bSTejun Heo mutex_lock(&wq_pool_attach_mutex); 53546b59808bSTejun Heo 5355197f6accSTejun Heo if (task->flags & PF_WQ_WORKER) { 5356197f6accSTejun Heo struct worker *worker = kthread_data(task); 5357197f6accSTejun Heo struct worker_pool *pool = worker->pool; 53586b59808bSTejun Heo 53596b59808bSTejun Heo if (pool) { 5360a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 53616b59808bSTejun Heo /* 5362197f6accSTejun Heo * ->desc tracks information (wq name or 5363197f6accSTejun Heo * set_worker_desc()) for the latest execution. If 5364197f6accSTejun Heo * current, prepend '+', otherwise '-'. 53656b59808bSTejun Heo */ 53666b59808bSTejun Heo if (worker->desc[0] != '\0') { 53676b59808bSTejun Heo if (worker->current_work) 53686b59808bSTejun Heo scnprintf(buf + off, size - off, "+%s", 53696b59808bSTejun Heo worker->desc); 53706b59808bSTejun Heo else 53716b59808bSTejun Heo scnprintf(buf + off, size - off, "-%s", 53726b59808bSTejun Heo worker->desc); 53736b59808bSTejun Heo } 5374a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 53756b59808bSTejun Heo } 5376197f6accSTejun Heo } 53776b59808bSTejun Heo 53786b59808bSTejun Heo mutex_unlock(&wq_pool_attach_mutex); 53796b59808bSTejun Heo } 53806b59808bSTejun Heo 538166448bc2SMathieu Malaterre #ifdef CONFIG_SMP 538266448bc2SMathieu Malaterre 5383db7bccf4STejun Heo /* 5384db7bccf4STejun Heo * CPU hotplug. 5385db7bccf4STejun Heo * 5386e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 5387112202d9STejun Heo * are a lot of assumptions on strong associations among work, pwq and 5388706026c2STejun Heo * pool which make migrating pending and scheduled works very 5389e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 539094cf58bbSTejun Heo * worker pools serve mix of short, long and very long running works making 5391e22bee78STejun Heo * blocked draining impractical. 5392e22bee78STejun Heo * 539324647570STejun Heo * This is solved by allowing the pools to be disassociated from the CPU 5394628c78e7STejun Heo * running as an unbound one and allowing it to be reattached later if the 5395628c78e7STejun Heo * cpu comes back online. 5396db7bccf4STejun Heo */ 5397db7bccf4STejun Heo 5398e8b3f8dbSLai Jiangshan static void unbind_workers(int cpu) 5399db7bccf4STejun Heo { 54004ce62e9eSTejun Heo struct worker_pool *pool; 5401db7bccf4STejun Heo struct worker *worker; 5402db7bccf4STejun Heo 5403f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 54041258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 5405a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 5406e22bee78STejun Heo 5407f2d5a0eeSTejun Heo /* 540892f9c5c4SLai Jiangshan * We've blocked all attach/detach operations. Make all workers 540994cf58bbSTejun Heo * unbound and set DISASSOCIATED. Before this, all workers 541011b45b0bSLai Jiangshan * must be on the cpu. After this, they may become diasporas. 5411b4ac9384SLai Jiangshan * And the preemption disabled section in their sched callbacks 5412b4ac9384SLai Jiangshan * are guaranteed to see WORKER_UNBOUND since the code here 5413b4ac9384SLai Jiangshan * is on the same cpu. 5414f2d5a0eeSTejun Heo */ 5415da028469SLai Jiangshan for_each_pool_worker(worker, pool) 5416403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 5417db7bccf4STejun Heo 541824647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 5419f2d5a0eeSTejun Heo 5420e22bee78STejun Heo /* 5421989442d7SLai Jiangshan * The handling of nr_running in sched callbacks are disabled 5422989442d7SLai Jiangshan * now. Zap nr_running. After this, nr_running stays zero and 5423989442d7SLai Jiangshan * need_more_worker() and keep_working() are always true as 5424989442d7SLai Jiangshan * long as the worklist is not empty. This pool now behaves as 5425989442d7SLai Jiangshan * an unbound (in terms of concurrency management) pool which 5426eb283428SLai Jiangshan * are served by workers tied to the pool. 5427e22bee78STejun Heo */ 5428bc35f7efSLai Jiangshan pool->nr_running = 0; 5429eb283428SLai Jiangshan 5430eb283428SLai Jiangshan /* 5431eb283428SLai Jiangshan * With concurrency management just turned off, a busy 5432eb283428SLai Jiangshan * worker blocking could lead to lengthy stalls. Kick off 5433eb283428SLai Jiangshan * unbound chain execution of currently pending work items. 5434eb283428SLai Jiangshan */ 54350219a352STejun Heo kick_pool(pool); 5436989442d7SLai Jiangshan 5437a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 5438989442d7SLai Jiangshan 5439793777bcSValentin Schneider for_each_pool_worker(worker, pool) 5440793777bcSValentin Schneider unbind_worker(worker); 5441989442d7SLai Jiangshan 5442989442d7SLai Jiangshan mutex_unlock(&wq_pool_attach_mutex); 5443eb283428SLai Jiangshan } 5444db7bccf4STejun Heo } 5445db7bccf4STejun Heo 5446bd7c089eSTejun Heo /** 5447bd7c089eSTejun Heo * rebind_workers - rebind all workers of a pool to the associated CPU 5448bd7c089eSTejun Heo * @pool: pool of interest 5449bd7c089eSTejun Heo * 5450a9ab775bSTejun Heo * @pool->cpu is coming online. Rebind all workers to the CPU. 5451bd7c089eSTejun Heo */ 5452bd7c089eSTejun Heo static void rebind_workers(struct worker_pool *pool) 5453bd7c089eSTejun Heo { 5454a9ab775bSTejun Heo struct worker *worker; 5455bd7c089eSTejun Heo 54561258fae7STejun Heo lockdep_assert_held(&wq_pool_attach_mutex); 5457bd7c089eSTejun Heo 5458bd7c089eSTejun Heo /* 5459a9ab775bSTejun Heo * Restore CPU affinity of all workers. As all idle workers should 5460a9ab775bSTejun Heo * be on the run-queue of the associated CPU before any local 5461402dd89dSShailendra Verma * wake-ups for concurrency management happen, restore CPU affinity 5462a9ab775bSTejun Heo * of all workers first and then clear UNBOUND. As we're called 5463a9ab775bSTejun Heo * from CPU_ONLINE, the following shouldn't fail. 5464bd7c089eSTejun Heo */ 5465c63a2e52SValentin Schneider for_each_pool_worker(worker, pool) { 5466c63a2e52SValentin Schneider kthread_set_per_cpu(worker->task, pool->cpu); 5467c63a2e52SValentin Schneider WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, 54689546b29eSTejun Heo pool_allowed_cpus(pool)) < 0); 5469c63a2e52SValentin Schneider } 5470a9ab775bSTejun Heo 5471a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 5472f7c17d26SWanpeng Li 54733de5e884SLai Jiangshan pool->flags &= ~POOL_DISASSOCIATED; 5474a9ab775bSTejun Heo 5475da028469SLai Jiangshan for_each_pool_worker(worker, pool) { 5476a9ab775bSTejun Heo unsigned int worker_flags = worker->flags; 5477a9ab775bSTejun Heo 5478a9ab775bSTejun Heo /* 5479a9ab775bSTejun Heo * We want to clear UNBOUND but can't directly call 5480a9ab775bSTejun Heo * worker_clr_flags() or adjust nr_running. Atomically 5481a9ab775bSTejun Heo * replace UNBOUND with another NOT_RUNNING flag REBOUND. 5482a9ab775bSTejun Heo * @worker will clear REBOUND using worker_clr_flags() when 5483a9ab775bSTejun Heo * it initiates the next execution cycle thus restoring 5484a9ab775bSTejun Heo * concurrency management. Note that when or whether 5485a9ab775bSTejun Heo * @worker clears REBOUND doesn't affect correctness. 5486a9ab775bSTejun Heo * 5487c95491edSMark Rutland * WRITE_ONCE() is necessary because @worker->flags may be 5488a9ab775bSTejun Heo * tested without holding any lock in 54896d25be57SThomas Gleixner * wq_worker_running(). Without it, NOT_RUNNING test may 5490a9ab775bSTejun Heo * fail incorrectly leading to premature concurrency 5491a9ab775bSTejun Heo * management operations. 5492bd7c089eSTejun Heo */ 5493a9ab775bSTejun Heo WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); 5494a9ab775bSTejun Heo worker_flags |= WORKER_REBOUND; 5495a9ab775bSTejun Heo worker_flags &= ~WORKER_UNBOUND; 5496c95491edSMark Rutland WRITE_ONCE(worker->flags, worker_flags); 5497bd7c089eSTejun Heo } 5498a9ab775bSTejun Heo 5499a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 5500bd7c089eSTejun Heo } 5501bd7c089eSTejun Heo 55027dbc725eSTejun Heo /** 55037dbc725eSTejun Heo * restore_unbound_workers_cpumask - restore cpumask of unbound workers 55047dbc725eSTejun Heo * @pool: unbound pool of interest 55057dbc725eSTejun Heo * @cpu: the CPU which is coming up 55067dbc725eSTejun Heo * 55077dbc725eSTejun Heo * An unbound pool may end up with a cpumask which doesn't have any online 55087dbc725eSTejun Heo * CPUs. When a worker of such pool get scheduled, the scheduler resets 55097dbc725eSTejun Heo * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any 55107dbc725eSTejun Heo * online CPU before, cpus_allowed of all its workers should be restored. 55117dbc725eSTejun Heo */ 55127dbc725eSTejun Heo static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) 55137dbc725eSTejun Heo { 55147dbc725eSTejun Heo static cpumask_t cpumask; 55157dbc725eSTejun Heo struct worker *worker; 55167dbc725eSTejun Heo 55171258fae7STejun Heo lockdep_assert_held(&wq_pool_attach_mutex); 55187dbc725eSTejun Heo 55197dbc725eSTejun Heo /* is @cpu allowed for @pool? */ 55207dbc725eSTejun Heo if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) 55217dbc725eSTejun Heo return; 55227dbc725eSTejun Heo 55237dbc725eSTejun Heo cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); 55247dbc725eSTejun Heo 55257dbc725eSTejun Heo /* as we're called from CPU_ONLINE, the following shouldn't fail */ 5526da028469SLai Jiangshan for_each_pool_worker(worker, pool) 5527d945b5e9SPeter Zijlstra WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0); 55287dbc725eSTejun Heo } 55297dbc725eSTejun Heo 55307ee681b2SThomas Gleixner int workqueue_prepare_cpu(unsigned int cpu) 55311da177e4SLinus Torvalds { 55324ce62e9eSTejun Heo struct worker_pool *pool; 55331da177e4SLinus Torvalds 5534f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 55353ce63377STejun Heo if (pool->nr_workers) 55363ce63377STejun Heo continue; 5537051e1850SLai Jiangshan if (!create_worker(pool)) 55387ee681b2SThomas Gleixner return -ENOMEM; 55393af24433SOleg Nesterov } 55407ee681b2SThomas Gleixner return 0; 55417ee681b2SThomas Gleixner } 55421da177e4SLinus Torvalds 55437ee681b2SThomas Gleixner int workqueue_online_cpu(unsigned int cpu) 55447ee681b2SThomas Gleixner { 55457ee681b2SThomas Gleixner struct worker_pool *pool; 55467ee681b2SThomas Gleixner struct workqueue_struct *wq; 55477ee681b2SThomas Gleixner int pi; 55487ee681b2SThomas Gleixner 554968e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 55507dbc725eSTejun Heo 55517dbc725eSTejun Heo for_each_pool(pool, pi) { 55521258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 555394cf58bbSTejun Heo 5554f05b558dSLai Jiangshan if (pool->cpu == cpu) 555594cf58bbSTejun Heo rebind_workers(pool); 5556f05b558dSLai Jiangshan else if (pool->cpu < 0) 55577dbc725eSTejun Heo restore_unbound_workers_cpumask(pool, cpu); 555894cf58bbSTejun Heo 55591258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 556094cf58bbSTejun Heo } 55617dbc725eSTejun Heo 5562fef59c9cSTejun Heo /* update pod affinity of unbound workqueues */ 55634cbfd3deSTejun Heo list_for_each_entry(wq, &workqueues, list) { 556484193c07STejun Heo struct workqueue_attrs *attrs = wq->unbound_attrs; 556584193c07STejun Heo 556684193c07STejun Heo if (attrs) { 556784193c07STejun Heo const struct wq_pod_type *pt = wqattrs_pod_type(attrs); 55684cbfd3deSTejun Heo int tcpu; 55694cbfd3deSTejun Heo 557084193c07STejun Heo for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) 5571fef59c9cSTejun Heo wq_update_pod(wq, tcpu, cpu, true); 55724cbfd3deSTejun Heo } 55734cbfd3deSTejun Heo } 55744c16bd32STejun Heo 557568e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 55767ee681b2SThomas Gleixner return 0; 557765758202STejun Heo } 557865758202STejun Heo 55797ee681b2SThomas Gleixner int workqueue_offline_cpu(unsigned int cpu) 558065758202STejun Heo { 55814c16bd32STejun Heo struct workqueue_struct *wq; 55828db25e78STejun Heo 55834c16bd32STejun Heo /* unbinding per-cpu workers should happen on the local CPU */ 5584e8b3f8dbSLai Jiangshan if (WARN_ON(cpu != smp_processor_id())) 5585e8b3f8dbSLai Jiangshan return -1; 5586e8b3f8dbSLai Jiangshan 5587e8b3f8dbSLai Jiangshan unbind_workers(cpu); 55884c16bd32STejun Heo 5589fef59c9cSTejun Heo /* update pod affinity of unbound workqueues */ 55904c16bd32STejun Heo mutex_lock(&wq_pool_mutex); 55914cbfd3deSTejun Heo list_for_each_entry(wq, &workqueues, list) { 559284193c07STejun Heo struct workqueue_attrs *attrs = wq->unbound_attrs; 559384193c07STejun Heo 559484193c07STejun Heo if (attrs) { 559584193c07STejun Heo const struct wq_pod_type *pt = wqattrs_pod_type(attrs); 55964cbfd3deSTejun Heo int tcpu; 55974cbfd3deSTejun Heo 559884193c07STejun Heo for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]]) 5599fef59c9cSTejun Heo wq_update_pod(wq, tcpu, cpu, false); 56004cbfd3deSTejun Heo } 56014cbfd3deSTejun Heo } 56024c16bd32STejun Heo mutex_unlock(&wq_pool_mutex); 56034c16bd32STejun Heo 56047ee681b2SThomas Gleixner return 0; 560565758202STejun Heo } 560665758202STejun Heo 56072d3854a3SRusty Russell struct work_for_cpu { 5608ed48ece2STejun Heo struct work_struct work; 56092d3854a3SRusty Russell long (*fn)(void *); 56102d3854a3SRusty Russell void *arg; 56112d3854a3SRusty Russell long ret; 56122d3854a3SRusty Russell }; 56132d3854a3SRusty Russell 5614ed48ece2STejun Heo static void work_for_cpu_fn(struct work_struct *work) 56152d3854a3SRusty Russell { 5616ed48ece2STejun Heo struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); 5617ed48ece2STejun Heo 56182d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 56192d3854a3SRusty Russell } 56202d3854a3SRusty Russell 56212d3854a3SRusty Russell /** 5622be2355b7SFrederic Weisbecker * work_on_cpu_key - run a function in thread context on a particular cpu 56232d3854a3SRusty Russell * @cpu: the cpu to run on 56242d3854a3SRusty Russell * @fn: the function to run 56252d3854a3SRusty Russell * @arg: the function arg 5626be2355b7SFrederic Weisbecker * @key: The lock class key for lock debugging purposes 56272d3854a3SRusty Russell * 562831ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 56296b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 5630d185af30SYacine Belkadi * 5631d185af30SYacine Belkadi * Return: The value @fn returns. 56322d3854a3SRusty Russell */ 5633be2355b7SFrederic Weisbecker long work_on_cpu_key(int cpu, long (*fn)(void *), 5634be2355b7SFrederic Weisbecker void *arg, struct lock_class_key *key) 56352d3854a3SRusty Russell { 5636ed48ece2STejun Heo struct work_for_cpu wfc = { .fn = fn, .arg = arg }; 56372d3854a3SRusty Russell 5638be2355b7SFrederic Weisbecker INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key); 5639ed48ece2STejun Heo schedule_work_on(cpu, &wfc.work); 564012997d1aSBjorn Helgaas flush_work(&wfc.work); 5641440a1136SChuansheng Liu destroy_work_on_stack(&wfc.work); 56422d3854a3SRusty Russell return wfc.ret; 56432d3854a3SRusty Russell } 5644be2355b7SFrederic Weisbecker EXPORT_SYMBOL_GPL(work_on_cpu_key); 56450e8d6a93SThomas Gleixner 56460e8d6a93SThomas Gleixner /** 5647be2355b7SFrederic Weisbecker * work_on_cpu_safe_key - run a function in thread context on a particular cpu 56480e8d6a93SThomas Gleixner * @cpu: the cpu to run on 56490e8d6a93SThomas Gleixner * @fn: the function to run 56500e8d6a93SThomas Gleixner * @arg: the function argument 5651be2355b7SFrederic Weisbecker * @key: The lock class key for lock debugging purposes 56520e8d6a93SThomas Gleixner * 56530e8d6a93SThomas Gleixner * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold 56540e8d6a93SThomas Gleixner * any locks which would prevent @fn from completing. 56550e8d6a93SThomas Gleixner * 56560e8d6a93SThomas Gleixner * Return: The value @fn returns. 56570e8d6a93SThomas Gleixner */ 5658be2355b7SFrederic Weisbecker long work_on_cpu_safe_key(int cpu, long (*fn)(void *), 5659be2355b7SFrederic Weisbecker void *arg, struct lock_class_key *key) 56600e8d6a93SThomas Gleixner { 56610e8d6a93SThomas Gleixner long ret = -ENODEV; 56620e8d6a93SThomas Gleixner 5663ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 56640e8d6a93SThomas Gleixner if (cpu_online(cpu)) 5665be2355b7SFrederic Weisbecker ret = work_on_cpu_key(cpu, fn, arg, key); 5666ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 56670e8d6a93SThomas Gleixner return ret; 56680e8d6a93SThomas Gleixner } 5669be2355b7SFrederic Weisbecker EXPORT_SYMBOL_GPL(work_on_cpu_safe_key); 56702d3854a3SRusty Russell #endif /* CONFIG_SMP */ 56712d3854a3SRusty Russell 5672a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 5673e7577c50SRusty Russell 5674a0a1a5fdSTejun Heo /** 5675a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 5676a0a1a5fdSTejun Heo * 567758a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 5678f97a4a1aSLai Jiangshan * workqueues will queue new works to their inactive_works list instead of 5679706026c2STejun Heo * pool->worklist. 5680a0a1a5fdSTejun Heo * 5681a0a1a5fdSTejun Heo * CONTEXT: 5682a357fc03SLai Jiangshan * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 5683a0a1a5fdSTejun Heo */ 5684a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 5685a0a1a5fdSTejun Heo { 568624b8a847STejun Heo struct workqueue_struct *wq; 568724b8a847STejun Heo struct pool_workqueue *pwq; 5688a0a1a5fdSTejun Heo 568968e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5690a0a1a5fdSTejun Heo 56916183c009STejun Heo WARN_ON_ONCE(workqueue_freezing); 5692a0a1a5fdSTejun Heo workqueue_freezing = true; 5693a0a1a5fdSTejun Heo 569424b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 5695a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 5696699ce097STejun Heo for_each_pwq(pwq, wq) 5697699ce097STejun Heo pwq_adjust_max_active(pwq); 5698a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 5699a1056305STejun Heo } 57005bcab335STejun Heo 570168e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5702a0a1a5fdSTejun Heo } 5703a0a1a5fdSTejun Heo 5704a0a1a5fdSTejun Heo /** 570558a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 5706a0a1a5fdSTejun Heo * 5707a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 5708a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 5709a0a1a5fdSTejun Heo * 5710a0a1a5fdSTejun Heo * CONTEXT: 571168e13a67SLai Jiangshan * Grabs and releases wq_pool_mutex. 5712a0a1a5fdSTejun Heo * 5713d185af30SYacine Belkadi * Return: 571458a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 571558a69cb4STejun Heo * is complete. 5716a0a1a5fdSTejun Heo */ 5717a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 5718a0a1a5fdSTejun Heo { 5719a0a1a5fdSTejun Heo bool busy = false; 572024b8a847STejun Heo struct workqueue_struct *wq; 572124b8a847STejun Heo struct pool_workqueue *pwq; 5722a0a1a5fdSTejun Heo 572368e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5724a0a1a5fdSTejun Heo 57256183c009STejun Heo WARN_ON_ONCE(!workqueue_freezing); 5726a0a1a5fdSTejun Heo 572724b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 572824b8a847STejun Heo if (!(wq->flags & WQ_FREEZABLE)) 572924b8a847STejun Heo continue; 5730a0a1a5fdSTejun Heo /* 5731a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 5732a0a1a5fdSTejun Heo * to peek without lock. 5733a0a1a5fdSTejun Heo */ 573424acfb71SThomas Gleixner rcu_read_lock(); 573524b8a847STejun Heo for_each_pwq(pwq, wq) { 57366183c009STejun Heo WARN_ON_ONCE(pwq->nr_active < 0); 5737112202d9STejun Heo if (pwq->nr_active) { 5738a0a1a5fdSTejun Heo busy = true; 573924acfb71SThomas Gleixner rcu_read_unlock(); 5740a0a1a5fdSTejun Heo goto out_unlock; 5741a0a1a5fdSTejun Heo } 5742a0a1a5fdSTejun Heo } 574324acfb71SThomas Gleixner rcu_read_unlock(); 5744a0a1a5fdSTejun Heo } 5745a0a1a5fdSTejun Heo out_unlock: 574668e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5747a0a1a5fdSTejun Heo return busy; 5748a0a1a5fdSTejun Heo } 5749a0a1a5fdSTejun Heo 5750a0a1a5fdSTejun Heo /** 5751a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 5752a0a1a5fdSTejun Heo * 5753a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 5754706026c2STejun Heo * frozen works are transferred to their respective pool worklists. 5755a0a1a5fdSTejun Heo * 5756a0a1a5fdSTejun Heo * CONTEXT: 5757a357fc03SLai Jiangshan * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 5758a0a1a5fdSTejun Heo */ 5759a0a1a5fdSTejun Heo void thaw_workqueues(void) 5760a0a1a5fdSTejun Heo { 576124b8a847STejun Heo struct workqueue_struct *wq; 576224b8a847STejun Heo struct pool_workqueue *pwq; 5763a0a1a5fdSTejun Heo 576468e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5765a0a1a5fdSTejun Heo 5766a0a1a5fdSTejun Heo if (!workqueue_freezing) 5767a0a1a5fdSTejun Heo goto out_unlock; 5768a0a1a5fdSTejun Heo 576974b414eaSLai Jiangshan workqueue_freezing = false; 577024b8a847STejun Heo 577124b8a847STejun Heo /* restore max_active and repopulate worklist */ 577224b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 5773a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 5774699ce097STejun Heo for_each_pwq(pwq, wq) 5775699ce097STejun Heo pwq_adjust_max_active(pwq); 5776a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 577724b8a847STejun Heo } 577824b8a847STejun Heo 5779a0a1a5fdSTejun Heo out_unlock: 578068e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5781a0a1a5fdSTejun Heo } 5782a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 5783a0a1a5fdSTejun Heo 578499c621efSLai Jiangshan static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask) 5785042f7df1SLai Jiangshan { 5786042f7df1SLai Jiangshan LIST_HEAD(ctxs); 5787042f7df1SLai Jiangshan int ret = 0; 5788042f7df1SLai Jiangshan struct workqueue_struct *wq; 5789042f7df1SLai Jiangshan struct apply_wqattrs_ctx *ctx, *n; 5790042f7df1SLai Jiangshan 5791042f7df1SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 5792042f7df1SLai Jiangshan 5793042f7df1SLai Jiangshan list_for_each_entry(wq, &workqueues, list) { 5794042f7df1SLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 5795042f7df1SLai Jiangshan continue; 5796ca10d851SWaiman Long 5797042f7df1SLai Jiangshan /* creating multiple pwqs breaks ordering guarantee */ 5798ca10d851SWaiman Long if (!list_empty(&wq->pwqs)) { 5799ca10d851SWaiman Long if (wq->flags & __WQ_ORDERED_EXPLICIT) 5800042f7df1SLai Jiangshan continue; 5801ca10d851SWaiman Long wq->flags &= ~__WQ_ORDERED; 5802ca10d851SWaiman Long } 5803042f7df1SLai Jiangshan 580499c621efSLai Jiangshan ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs, unbound_cpumask); 580584193c07STejun Heo if (IS_ERR(ctx)) { 580684193c07STejun Heo ret = PTR_ERR(ctx); 5807042f7df1SLai Jiangshan break; 5808042f7df1SLai Jiangshan } 5809042f7df1SLai Jiangshan 5810042f7df1SLai Jiangshan list_add_tail(&ctx->list, &ctxs); 5811042f7df1SLai Jiangshan } 5812042f7df1SLai Jiangshan 5813042f7df1SLai Jiangshan list_for_each_entry_safe(ctx, n, &ctxs, list) { 5814042f7df1SLai Jiangshan if (!ret) 5815042f7df1SLai Jiangshan apply_wqattrs_commit(ctx); 5816042f7df1SLai Jiangshan apply_wqattrs_cleanup(ctx); 5817042f7df1SLai Jiangshan } 5818042f7df1SLai Jiangshan 581999c621efSLai Jiangshan if (!ret) { 582099c621efSLai Jiangshan mutex_lock(&wq_pool_attach_mutex); 582199c621efSLai Jiangshan cpumask_copy(wq_unbound_cpumask, unbound_cpumask); 582299c621efSLai Jiangshan mutex_unlock(&wq_pool_attach_mutex); 582399c621efSLai Jiangshan } 5824042f7df1SLai Jiangshan return ret; 5825042f7df1SLai Jiangshan } 5826042f7df1SLai Jiangshan 5827042f7df1SLai Jiangshan /** 5828042f7df1SLai Jiangshan * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask 5829042f7df1SLai Jiangshan * @cpumask: the cpumask to set 5830042f7df1SLai Jiangshan * 5831042f7df1SLai Jiangshan * The low-level workqueues cpumask is a global cpumask that limits 5832042f7df1SLai Jiangshan * the affinity of all unbound workqueues. This function check the @cpumask 5833042f7df1SLai Jiangshan * and apply it to all unbound workqueues and updates all pwqs of them. 5834042f7df1SLai Jiangshan * 583567dc8325SCai Huoqing * Return: 0 - Success 5836042f7df1SLai Jiangshan * -EINVAL - Invalid @cpumask 5837042f7df1SLai Jiangshan * -ENOMEM - Failed to allocate memory for attrs or pwqs. 5838042f7df1SLai Jiangshan */ 5839042f7df1SLai Jiangshan int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) 5840042f7df1SLai Jiangshan { 5841042f7df1SLai Jiangshan int ret = -EINVAL; 5842042f7df1SLai Jiangshan 5843c98a9805STal Shorer /* 5844c98a9805STal Shorer * Not excluding isolated cpus on purpose. 5845c98a9805STal Shorer * If the user wishes to include them, we allow that. 5846c98a9805STal Shorer */ 5847042f7df1SLai Jiangshan cpumask_and(cpumask, cpumask, cpu_possible_mask); 5848042f7df1SLai Jiangshan if (!cpumask_empty(cpumask)) { 5849a0111cf6SLai Jiangshan apply_wqattrs_lock(); 5850d25302e4SMenglong Dong if (cpumask_equal(cpumask, wq_unbound_cpumask)) { 5851d25302e4SMenglong Dong ret = 0; 5852d25302e4SMenglong Dong goto out_unlock; 5853d25302e4SMenglong Dong } 5854d25302e4SMenglong Dong 585599c621efSLai Jiangshan ret = workqueue_apply_unbound_cpumask(cpumask); 5856042f7df1SLai Jiangshan 5857d25302e4SMenglong Dong out_unlock: 5858a0111cf6SLai Jiangshan apply_wqattrs_unlock(); 5859042f7df1SLai Jiangshan } 5860042f7df1SLai Jiangshan 5861042f7df1SLai Jiangshan return ret; 5862042f7df1SLai Jiangshan } 5863042f7df1SLai Jiangshan 586463c5484eSTejun Heo static int parse_affn_scope(const char *val) 586563c5484eSTejun Heo { 586663c5484eSTejun Heo int i; 586763c5484eSTejun Heo 586863c5484eSTejun Heo for (i = 0; i < ARRAY_SIZE(wq_affn_names); i++) { 586963c5484eSTejun Heo if (!strncasecmp(val, wq_affn_names[i], strlen(wq_affn_names[i]))) 587063c5484eSTejun Heo return i; 587163c5484eSTejun Heo } 587263c5484eSTejun Heo return -EINVAL; 587363c5484eSTejun Heo } 587463c5484eSTejun Heo 587563c5484eSTejun Heo static int wq_affn_dfl_set(const char *val, const struct kernel_param *kp) 587663c5484eSTejun Heo { 5877523a301eSTejun Heo struct workqueue_struct *wq; 5878523a301eSTejun Heo int affn, cpu; 587963c5484eSTejun Heo 588063c5484eSTejun Heo affn = parse_affn_scope(val); 588163c5484eSTejun Heo if (affn < 0) 588263c5484eSTejun Heo return affn; 5883523a301eSTejun Heo if (affn == WQ_AFFN_DFL) 5884523a301eSTejun Heo return -EINVAL; 5885523a301eSTejun Heo 5886523a301eSTejun Heo cpus_read_lock(); 5887523a301eSTejun Heo mutex_lock(&wq_pool_mutex); 588863c5484eSTejun Heo 588963c5484eSTejun Heo wq_affn_dfl = affn; 5890523a301eSTejun Heo 5891523a301eSTejun Heo list_for_each_entry(wq, &workqueues, list) { 5892523a301eSTejun Heo for_each_online_cpu(cpu) { 5893523a301eSTejun Heo wq_update_pod(wq, cpu, cpu, true); 5894523a301eSTejun Heo } 5895523a301eSTejun Heo } 5896523a301eSTejun Heo 5897523a301eSTejun Heo mutex_unlock(&wq_pool_mutex); 5898523a301eSTejun Heo cpus_read_unlock(); 5899523a301eSTejun Heo 590063c5484eSTejun Heo return 0; 590163c5484eSTejun Heo } 590263c5484eSTejun Heo 590363c5484eSTejun Heo static int wq_affn_dfl_get(char *buffer, const struct kernel_param *kp) 590463c5484eSTejun Heo { 590563c5484eSTejun Heo return scnprintf(buffer, PAGE_SIZE, "%s\n", wq_affn_names[wq_affn_dfl]); 590663c5484eSTejun Heo } 590763c5484eSTejun Heo 590863c5484eSTejun Heo static const struct kernel_param_ops wq_affn_dfl_ops = { 590963c5484eSTejun Heo .set = wq_affn_dfl_set, 591063c5484eSTejun Heo .get = wq_affn_dfl_get, 591163c5484eSTejun Heo }; 591263c5484eSTejun Heo 591363c5484eSTejun Heo module_param_cb(default_affinity_scope, &wq_affn_dfl_ops, NULL, 0644); 591463c5484eSTejun Heo 59156ba94429SFrederic Weisbecker #ifdef CONFIG_SYSFS 59166ba94429SFrederic Weisbecker /* 59176ba94429SFrederic Weisbecker * Workqueues with WQ_SYSFS flag set is visible to userland via 59186ba94429SFrederic Weisbecker * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the 59196ba94429SFrederic Weisbecker * following attributes. 59206ba94429SFrederic Weisbecker * 59216ba94429SFrederic Weisbecker * per_cpu RO bool : whether the workqueue is per-cpu or unbound 59226ba94429SFrederic Weisbecker * max_active RW int : maximum number of in-flight work items 59236ba94429SFrederic Weisbecker * 59246ba94429SFrederic Weisbecker * Unbound workqueues have the following extra attributes. 59256ba94429SFrederic Weisbecker * 59266ba94429SFrederic Weisbecker * nice RW int : nice value of the workers 59276ba94429SFrederic Weisbecker * cpumask RW mask : bitmask of allowed CPUs for the workers 592863c5484eSTejun Heo * affinity_scope RW str : worker CPU affinity scope (cache, numa, none) 59298639ecebSTejun Heo * affinity_strict RW bool : worker CPU affinity is strict 59306ba94429SFrederic Weisbecker */ 59316ba94429SFrederic Weisbecker struct wq_device { 59326ba94429SFrederic Weisbecker struct workqueue_struct *wq; 59336ba94429SFrederic Weisbecker struct device dev; 59346ba94429SFrederic Weisbecker }; 59356ba94429SFrederic Weisbecker 59366ba94429SFrederic Weisbecker static struct workqueue_struct *dev_to_wq(struct device *dev) 59376ba94429SFrederic Weisbecker { 59386ba94429SFrederic Weisbecker struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 59396ba94429SFrederic Weisbecker 59406ba94429SFrederic Weisbecker return wq_dev->wq; 59416ba94429SFrederic Weisbecker } 59426ba94429SFrederic Weisbecker 59436ba94429SFrederic Weisbecker static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, 59446ba94429SFrederic Weisbecker char *buf) 59456ba94429SFrederic Weisbecker { 59466ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 59476ba94429SFrederic Weisbecker 59486ba94429SFrederic Weisbecker return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); 59496ba94429SFrederic Weisbecker } 59506ba94429SFrederic Weisbecker static DEVICE_ATTR_RO(per_cpu); 59516ba94429SFrederic Weisbecker 59526ba94429SFrederic Weisbecker static ssize_t max_active_show(struct device *dev, 59536ba94429SFrederic Weisbecker struct device_attribute *attr, char *buf) 59546ba94429SFrederic Weisbecker { 59556ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 59566ba94429SFrederic Weisbecker 59576ba94429SFrederic Weisbecker return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); 59586ba94429SFrederic Weisbecker } 59596ba94429SFrederic Weisbecker 59606ba94429SFrederic Weisbecker static ssize_t max_active_store(struct device *dev, 59616ba94429SFrederic Weisbecker struct device_attribute *attr, const char *buf, 59626ba94429SFrederic Weisbecker size_t count) 59636ba94429SFrederic Weisbecker { 59646ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 59656ba94429SFrederic Weisbecker int val; 59666ba94429SFrederic Weisbecker 59676ba94429SFrederic Weisbecker if (sscanf(buf, "%d", &val) != 1 || val <= 0) 59686ba94429SFrederic Weisbecker return -EINVAL; 59696ba94429SFrederic Weisbecker 59706ba94429SFrederic Weisbecker workqueue_set_max_active(wq, val); 59716ba94429SFrederic Weisbecker return count; 59726ba94429SFrederic Weisbecker } 59736ba94429SFrederic Weisbecker static DEVICE_ATTR_RW(max_active); 59746ba94429SFrederic Weisbecker 59756ba94429SFrederic Weisbecker static struct attribute *wq_sysfs_attrs[] = { 59766ba94429SFrederic Weisbecker &dev_attr_per_cpu.attr, 59776ba94429SFrederic Weisbecker &dev_attr_max_active.attr, 59786ba94429SFrederic Weisbecker NULL, 59796ba94429SFrederic Weisbecker }; 59806ba94429SFrederic Weisbecker ATTRIBUTE_GROUPS(wq_sysfs); 59816ba94429SFrederic Weisbecker 59826ba94429SFrederic Weisbecker static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, 59836ba94429SFrederic Weisbecker char *buf) 59846ba94429SFrederic Weisbecker { 59856ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 59866ba94429SFrederic Weisbecker int written; 59876ba94429SFrederic Weisbecker 59886ba94429SFrederic Weisbecker mutex_lock(&wq->mutex); 59896ba94429SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); 59906ba94429SFrederic Weisbecker mutex_unlock(&wq->mutex); 59916ba94429SFrederic Weisbecker 59926ba94429SFrederic Weisbecker return written; 59936ba94429SFrederic Weisbecker } 59946ba94429SFrederic Weisbecker 59956ba94429SFrederic Weisbecker /* prepare workqueue_attrs for sysfs store operations */ 59966ba94429SFrederic Weisbecker static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) 59976ba94429SFrederic Weisbecker { 59986ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 59996ba94429SFrederic Weisbecker 6000899a94feSLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 6001899a94feSLai Jiangshan 6002be69d00dSThomas Gleixner attrs = alloc_workqueue_attrs(); 60036ba94429SFrederic Weisbecker if (!attrs) 60046ba94429SFrederic Weisbecker return NULL; 60056ba94429SFrederic Weisbecker 60066ba94429SFrederic Weisbecker copy_workqueue_attrs(attrs, wq->unbound_attrs); 60076ba94429SFrederic Weisbecker return attrs; 60086ba94429SFrederic Weisbecker } 60096ba94429SFrederic Weisbecker 60106ba94429SFrederic Weisbecker static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, 60116ba94429SFrederic Weisbecker const char *buf, size_t count) 60126ba94429SFrederic Weisbecker { 60136ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 60146ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 6015d4d3e257SLai Jiangshan int ret = -ENOMEM; 6016d4d3e257SLai Jiangshan 6017d4d3e257SLai Jiangshan apply_wqattrs_lock(); 60186ba94429SFrederic Weisbecker 60196ba94429SFrederic Weisbecker attrs = wq_sysfs_prep_attrs(wq); 60206ba94429SFrederic Weisbecker if (!attrs) 6021d4d3e257SLai Jiangshan goto out_unlock; 60226ba94429SFrederic Weisbecker 60236ba94429SFrederic Weisbecker if (sscanf(buf, "%d", &attrs->nice) == 1 && 60246ba94429SFrederic Weisbecker attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) 6025d4d3e257SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 60266ba94429SFrederic Weisbecker else 60276ba94429SFrederic Weisbecker ret = -EINVAL; 60286ba94429SFrederic Weisbecker 6029d4d3e257SLai Jiangshan out_unlock: 6030d4d3e257SLai Jiangshan apply_wqattrs_unlock(); 60316ba94429SFrederic Weisbecker free_workqueue_attrs(attrs); 60326ba94429SFrederic Weisbecker return ret ?: count; 60336ba94429SFrederic Weisbecker } 60346ba94429SFrederic Weisbecker 60356ba94429SFrederic Weisbecker static ssize_t wq_cpumask_show(struct device *dev, 60366ba94429SFrederic Weisbecker struct device_attribute *attr, char *buf) 60376ba94429SFrederic Weisbecker { 60386ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 60396ba94429SFrederic Weisbecker int written; 60406ba94429SFrederic Weisbecker 60416ba94429SFrederic Weisbecker mutex_lock(&wq->mutex); 60426ba94429SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%*pb\n", 60436ba94429SFrederic Weisbecker cpumask_pr_args(wq->unbound_attrs->cpumask)); 60446ba94429SFrederic Weisbecker mutex_unlock(&wq->mutex); 60456ba94429SFrederic Weisbecker return written; 60466ba94429SFrederic Weisbecker } 60476ba94429SFrederic Weisbecker 60486ba94429SFrederic Weisbecker static ssize_t wq_cpumask_store(struct device *dev, 60496ba94429SFrederic Weisbecker struct device_attribute *attr, 60506ba94429SFrederic Weisbecker const char *buf, size_t count) 60516ba94429SFrederic Weisbecker { 60526ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 60536ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 6054d4d3e257SLai Jiangshan int ret = -ENOMEM; 6055d4d3e257SLai Jiangshan 6056d4d3e257SLai Jiangshan apply_wqattrs_lock(); 60576ba94429SFrederic Weisbecker 60586ba94429SFrederic Weisbecker attrs = wq_sysfs_prep_attrs(wq); 60596ba94429SFrederic Weisbecker if (!attrs) 6060d4d3e257SLai Jiangshan goto out_unlock; 60616ba94429SFrederic Weisbecker 60626ba94429SFrederic Weisbecker ret = cpumask_parse(buf, attrs->cpumask); 60636ba94429SFrederic Weisbecker if (!ret) 6064d4d3e257SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 60656ba94429SFrederic Weisbecker 6066d4d3e257SLai Jiangshan out_unlock: 6067d4d3e257SLai Jiangshan apply_wqattrs_unlock(); 60686ba94429SFrederic Weisbecker free_workqueue_attrs(attrs); 60696ba94429SFrederic Weisbecker return ret ?: count; 60706ba94429SFrederic Weisbecker } 60716ba94429SFrederic Weisbecker 607263c5484eSTejun Heo static ssize_t wq_affn_scope_show(struct device *dev, 607363c5484eSTejun Heo struct device_attribute *attr, char *buf) 607463c5484eSTejun Heo { 607563c5484eSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 607663c5484eSTejun Heo int written; 607763c5484eSTejun Heo 607863c5484eSTejun Heo mutex_lock(&wq->mutex); 6079523a301eSTejun Heo if (wq->unbound_attrs->affn_scope == WQ_AFFN_DFL) 6080523a301eSTejun Heo written = scnprintf(buf, PAGE_SIZE, "%s (%s)\n", 6081523a301eSTejun Heo wq_affn_names[WQ_AFFN_DFL], 6082523a301eSTejun Heo wq_affn_names[wq_affn_dfl]); 6083523a301eSTejun Heo else 608463c5484eSTejun Heo written = scnprintf(buf, PAGE_SIZE, "%s\n", 608563c5484eSTejun Heo wq_affn_names[wq->unbound_attrs->affn_scope]); 608663c5484eSTejun Heo mutex_unlock(&wq->mutex); 608763c5484eSTejun Heo 608863c5484eSTejun Heo return written; 608963c5484eSTejun Heo } 609063c5484eSTejun Heo 609163c5484eSTejun Heo static ssize_t wq_affn_scope_store(struct device *dev, 609263c5484eSTejun Heo struct device_attribute *attr, 609363c5484eSTejun Heo const char *buf, size_t count) 609463c5484eSTejun Heo { 609563c5484eSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 609663c5484eSTejun Heo struct workqueue_attrs *attrs; 609763c5484eSTejun Heo int affn, ret = -ENOMEM; 609863c5484eSTejun Heo 609963c5484eSTejun Heo affn = parse_affn_scope(buf); 610063c5484eSTejun Heo if (affn < 0) 610163c5484eSTejun Heo return affn; 610263c5484eSTejun Heo 610363c5484eSTejun Heo apply_wqattrs_lock(); 610463c5484eSTejun Heo attrs = wq_sysfs_prep_attrs(wq); 610563c5484eSTejun Heo if (attrs) { 610663c5484eSTejun Heo attrs->affn_scope = affn; 610763c5484eSTejun Heo ret = apply_workqueue_attrs_locked(wq, attrs); 610863c5484eSTejun Heo } 610963c5484eSTejun Heo apply_wqattrs_unlock(); 611063c5484eSTejun Heo free_workqueue_attrs(attrs); 611163c5484eSTejun Heo return ret ?: count; 611263c5484eSTejun Heo } 611363c5484eSTejun Heo 61148639ecebSTejun Heo static ssize_t wq_affinity_strict_show(struct device *dev, 61158639ecebSTejun Heo struct device_attribute *attr, char *buf) 61168639ecebSTejun Heo { 61178639ecebSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 61188639ecebSTejun Heo 61198639ecebSTejun Heo return scnprintf(buf, PAGE_SIZE, "%d\n", 61208639ecebSTejun Heo wq->unbound_attrs->affn_strict); 61218639ecebSTejun Heo } 61228639ecebSTejun Heo 61238639ecebSTejun Heo static ssize_t wq_affinity_strict_store(struct device *dev, 61248639ecebSTejun Heo struct device_attribute *attr, 61258639ecebSTejun Heo const char *buf, size_t count) 61268639ecebSTejun Heo { 61278639ecebSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 61288639ecebSTejun Heo struct workqueue_attrs *attrs; 61298639ecebSTejun Heo int v, ret = -ENOMEM; 61308639ecebSTejun Heo 61318639ecebSTejun Heo if (sscanf(buf, "%d", &v) != 1) 61328639ecebSTejun Heo return -EINVAL; 61338639ecebSTejun Heo 61348639ecebSTejun Heo apply_wqattrs_lock(); 61358639ecebSTejun Heo attrs = wq_sysfs_prep_attrs(wq); 61368639ecebSTejun Heo if (attrs) { 61378639ecebSTejun Heo attrs->affn_strict = (bool)v; 61388639ecebSTejun Heo ret = apply_workqueue_attrs_locked(wq, attrs); 61398639ecebSTejun Heo } 61408639ecebSTejun Heo apply_wqattrs_unlock(); 61418639ecebSTejun Heo free_workqueue_attrs(attrs); 61428639ecebSTejun Heo return ret ?: count; 61438639ecebSTejun Heo } 61448639ecebSTejun Heo 61456ba94429SFrederic Weisbecker static struct device_attribute wq_sysfs_unbound_attrs[] = { 61466ba94429SFrederic Weisbecker __ATTR(nice, 0644, wq_nice_show, wq_nice_store), 61476ba94429SFrederic Weisbecker __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), 614863c5484eSTejun Heo __ATTR(affinity_scope, 0644, wq_affn_scope_show, wq_affn_scope_store), 61498639ecebSTejun Heo __ATTR(affinity_strict, 0644, wq_affinity_strict_show, wq_affinity_strict_store), 61506ba94429SFrederic Weisbecker __ATTR_NULL, 61516ba94429SFrederic Weisbecker }; 61526ba94429SFrederic Weisbecker 61536ba94429SFrederic Weisbecker static struct bus_type wq_subsys = { 61546ba94429SFrederic Weisbecker .name = "workqueue", 61556ba94429SFrederic Weisbecker .dev_groups = wq_sysfs_groups, 61566ba94429SFrederic Weisbecker }; 61576ba94429SFrederic Weisbecker 6158b05a7928SFrederic Weisbecker static ssize_t wq_unbound_cpumask_show(struct device *dev, 6159b05a7928SFrederic Weisbecker struct device_attribute *attr, char *buf) 6160b05a7928SFrederic Weisbecker { 6161b05a7928SFrederic Weisbecker int written; 6162b05a7928SFrederic Weisbecker 6163042f7df1SLai Jiangshan mutex_lock(&wq_pool_mutex); 6164b05a7928SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%*pb\n", 6165b05a7928SFrederic Weisbecker cpumask_pr_args(wq_unbound_cpumask)); 6166042f7df1SLai Jiangshan mutex_unlock(&wq_pool_mutex); 6167b05a7928SFrederic Weisbecker 6168b05a7928SFrederic Weisbecker return written; 6169b05a7928SFrederic Weisbecker } 6170b05a7928SFrederic Weisbecker 6171042f7df1SLai Jiangshan static ssize_t wq_unbound_cpumask_store(struct device *dev, 6172042f7df1SLai Jiangshan struct device_attribute *attr, const char *buf, size_t count) 6173042f7df1SLai Jiangshan { 6174042f7df1SLai Jiangshan cpumask_var_t cpumask; 6175042f7df1SLai Jiangshan int ret; 6176042f7df1SLai Jiangshan 6177042f7df1SLai Jiangshan if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) 6178042f7df1SLai Jiangshan return -ENOMEM; 6179042f7df1SLai Jiangshan 6180042f7df1SLai Jiangshan ret = cpumask_parse(buf, cpumask); 6181042f7df1SLai Jiangshan if (!ret) 6182042f7df1SLai Jiangshan ret = workqueue_set_unbound_cpumask(cpumask); 6183042f7df1SLai Jiangshan 6184042f7df1SLai Jiangshan free_cpumask_var(cpumask); 6185042f7df1SLai Jiangshan return ret ? ret : count; 6186042f7df1SLai Jiangshan } 6187042f7df1SLai Jiangshan 6188b05a7928SFrederic Weisbecker static struct device_attribute wq_sysfs_cpumask_attr = 6189042f7df1SLai Jiangshan __ATTR(cpumask, 0644, wq_unbound_cpumask_show, 6190042f7df1SLai Jiangshan wq_unbound_cpumask_store); 6191b05a7928SFrederic Weisbecker 61926ba94429SFrederic Weisbecker static int __init wq_sysfs_init(void) 61936ba94429SFrederic Weisbecker { 6194686f6697SGreg Kroah-Hartman struct device *dev_root; 6195b05a7928SFrederic Weisbecker int err; 6196b05a7928SFrederic Weisbecker 6197b05a7928SFrederic Weisbecker err = subsys_virtual_register(&wq_subsys, NULL); 6198b05a7928SFrederic Weisbecker if (err) 6199b05a7928SFrederic Weisbecker return err; 6200b05a7928SFrederic Weisbecker 6201686f6697SGreg Kroah-Hartman dev_root = bus_get_dev_root(&wq_subsys); 6202686f6697SGreg Kroah-Hartman if (dev_root) { 6203686f6697SGreg Kroah-Hartman err = device_create_file(dev_root, &wq_sysfs_cpumask_attr); 6204686f6697SGreg Kroah-Hartman put_device(dev_root); 6205686f6697SGreg Kroah-Hartman } 6206686f6697SGreg Kroah-Hartman return err; 62076ba94429SFrederic Weisbecker } 62086ba94429SFrederic Weisbecker core_initcall(wq_sysfs_init); 62096ba94429SFrederic Weisbecker 62106ba94429SFrederic Weisbecker static void wq_device_release(struct device *dev) 62116ba94429SFrederic Weisbecker { 62126ba94429SFrederic Weisbecker struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 62136ba94429SFrederic Weisbecker 62146ba94429SFrederic Weisbecker kfree(wq_dev); 62156ba94429SFrederic Weisbecker } 62166ba94429SFrederic Weisbecker 62176ba94429SFrederic Weisbecker /** 62186ba94429SFrederic Weisbecker * workqueue_sysfs_register - make a workqueue visible in sysfs 62196ba94429SFrederic Weisbecker * @wq: the workqueue to register 62206ba94429SFrederic Weisbecker * 62216ba94429SFrederic Weisbecker * Expose @wq in sysfs under /sys/bus/workqueue/devices. 62226ba94429SFrederic Weisbecker * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set 62236ba94429SFrederic Weisbecker * which is the preferred method. 62246ba94429SFrederic Weisbecker * 62256ba94429SFrederic Weisbecker * Workqueue user should use this function directly iff it wants to apply 62266ba94429SFrederic Weisbecker * workqueue_attrs before making the workqueue visible in sysfs; otherwise, 62276ba94429SFrederic Weisbecker * apply_workqueue_attrs() may race against userland updating the 62286ba94429SFrederic Weisbecker * attributes. 62296ba94429SFrederic Weisbecker * 62306ba94429SFrederic Weisbecker * Return: 0 on success, -errno on failure. 62316ba94429SFrederic Weisbecker */ 62326ba94429SFrederic Weisbecker int workqueue_sysfs_register(struct workqueue_struct *wq) 62336ba94429SFrederic Weisbecker { 62346ba94429SFrederic Weisbecker struct wq_device *wq_dev; 62356ba94429SFrederic Weisbecker int ret; 62366ba94429SFrederic Weisbecker 62376ba94429SFrederic Weisbecker /* 6238402dd89dSShailendra Verma * Adjusting max_active or creating new pwqs by applying 62396ba94429SFrederic Weisbecker * attributes breaks ordering guarantee. Disallow exposing ordered 62406ba94429SFrederic Weisbecker * workqueues. 62416ba94429SFrederic Weisbecker */ 62420a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 62436ba94429SFrederic Weisbecker return -EINVAL; 62446ba94429SFrederic Weisbecker 62456ba94429SFrederic Weisbecker wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); 62466ba94429SFrederic Weisbecker if (!wq_dev) 62476ba94429SFrederic Weisbecker return -ENOMEM; 62486ba94429SFrederic Weisbecker 62496ba94429SFrederic Weisbecker wq_dev->wq = wq; 62506ba94429SFrederic Weisbecker wq_dev->dev.bus = &wq_subsys; 62516ba94429SFrederic Weisbecker wq_dev->dev.release = wq_device_release; 625223217b44SLars-Peter Clausen dev_set_name(&wq_dev->dev, "%s", wq->name); 62536ba94429SFrederic Weisbecker 62546ba94429SFrederic Weisbecker /* 62556ba94429SFrederic Weisbecker * unbound_attrs are created separately. Suppress uevent until 62566ba94429SFrederic Weisbecker * everything is ready. 62576ba94429SFrederic Weisbecker */ 62586ba94429SFrederic Weisbecker dev_set_uevent_suppress(&wq_dev->dev, true); 62596ba94429SFrederic Weisbecker 62606ba94429SFrederic Weisbecker ret = device_register(&wq_dev->dev); 62616ba94429SFrederic Weisbecker if (ret) { 6262537f4146SArvind Yadav put_device(&wq_dev->dev); 62636ba94429SFrederic Weisbecker wq->wq_dev = NULL; 62646ba94429SFrederic Weisbecker return ret; 62656ba94429SFrederic Weisbecker } 62666ba94429SFrederic Weisbecker 62676ba94429SFrederic Weisbecker if (wq->flags & WQ_UNBOUND) { 62686ba94429SFrederic Weisbecker struct device_attribute *attr; 62696ba94429SFrederic Weisbecker 62706ba94429SFrederic Weisbecker for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { 62716ba94429SFrederic Weisbecker ret = device_create_file(&wq_dev->dev, attr); 62726ba94429SFrederic Weisbecker if (ret) { 62736ba94429SFrederic Weisbecker device_unregister(&wq_dev->dev); 62746ba94429SFrederic Weisbecker wq->wq_dev = NULL; 62756ba94429SFrederic Weisbecker return ret; 62766ba94429SFrederic Weisbecker } 62776ba94429SFrederic Weisbecker } 62786ba94429SFrederic Weisbecker } 62796ba94429SFrederic Weisbecker 62806ba94429SFrederic Weisbecker dev_set_uevent_suppress(&wq_dev->dev, false); 62816ba94429SFrederic Weisbecker kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); 62826ba94429SFrederic Weisbecker return 0; 62836ba94429SFrederic Weisbecker } 62846ba94429SFrederic Weisbecker 62856ba94429SFrederic Weisbecker /** 62866ba94429SFrederic Weisbecker * workqueue_sysfs_unregister - undo workqueue_sysfs_register() 62876ba94429SFrederic Weisbecker * @wq: the workqueue to unregister 62886ba94429SFrederic Weisbecker * 62896ba94429SFrederic Weisbecker * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. 62906ba94429SFrederic Weisbecker */ 62916ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq) 62926ba94429SFrederic Weisbecker { 62936ba94429SFrederic Weisbecker struct wq_device *wq_dev = wq->wq_dev; 62946ba94429SFrederic Weisbecker 62956ba94429SFrederic Weisbecker if (!wq->wq_dev) 62966ba94429SFrederic Weisbecker return; 62976ba94429SFrederic Weisbecker 62986ba94429SFrederic Weisbecker wq->wq_dev = NULL; 62996ba94429SFrederic Weisbecker device_unregister(&wq_dev->dev); 63006ba94429SFrederic Weisbecker } 63016ba94429SFrederic Weisbecker #else /* CONFIG_SYSFS */ 63026ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } 63036ba94429SFrederic Weisbecker #endif /* CONFIG_SYSFS */ 63046ba94429SFrederic Weisbecker 630582607adcSTejun Heo /* 630682607adcSTejun Heo * Workqueue watchdog. 630782607adcSTejun Heo * 630882607adcSTejun Heo * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal 630982607adcSTejun Heo * flush dependency, a concurrency managed work item which stays RUNNING 631082607adcSTejun Heo * indefinitely. Workqueue stalls can be very difficult to debug as the 631182607adcSTejun Heo * usual warning mechanisms don't trigger and internal workqueue state is 631282607adcSTejun Heo * largely opaque. 631382607adcSTejun Heo * 631482607adcSTejun Heo * Workqueue watchdog monitors all worker pools periodically and dumps 631582607adcSTejun Heo * state if some pools failed to make forward progress for a while where 631682607adcSTejun Heo * forward progress is defined as the first item on ->worklist changing. 631782607adcSTejun Heo * 631882607adcSTejun Heo * This mechanism is controlled through the kernel parameter 631982607adcSTejun Heo * "workqueue.watchdog_thresh" which can be updated at runtime through the 632082607adcSTejun Heo * corresponding sysfs parameter file. 632182607adcSTejun Heo */ 632282607adcSTejun Heo #ifdef CONFIG_WQ_WATCHDOG 632382607adcSTejun Heo 632482607adcSTejun Heo static unsigned long wq_watchdog_thresh = 30; 63255cd79d6aSKees Cook static struct timer_list wq_watchdog_timer; 632682607adcSTejun Heo 632782607adcSTejun Heo static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; 632882607adcSTejun Heo static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; 632982607adcSTejun Heo 6330cd2440d6SPetr Mladek /* 6331cd2440d6SPetr Mladek * Show workers that might prevent the processing of pending work items. 6332cd2440d6SPetr Mladek * The only candidates are CPU-bound workers in the running state. 6333cd2440d6SPetr Mladek * Pending work items should be handled by another idle worker 6334cd2440d6SPetr Mladek * in all other situations. 6335cd2440d6SPetr Mladek */ 6336cd2440d6SPetr Mladek static void show_cpu_pool_hog(struct worker_pool *pool) 6337cd2440d6SPetr Mladek { 6338cd2440d6SPetr Mladek struct worker *worker; 6339cd2440d6SPetr Mladek unsigned long flags; 6340cd2440d6SPetr Mladek int bkt; 6341cd2440d6SPetr Mladek 6342cd2440d6SPetr Mladek raw_spin_lock_irqsave(&pool->lock, flags); 6343cd2440d6SPetr Mladek 6344cd2440d6SPetr Mladek hash_for_each(pool->busy_hash, bkt, worker, hentry) { 6345cd2440d6SPetr Mladek if (task_is_running(worker->task)) { 6346cd2440d6SPetr Mladek /* 6347cd2440d6SPetr Mladek * Defer printing to avoid deadlocks in console 6348cd2440d6SPetr Mladek * drivers that queue work while holding locks 6349cd2440d6SPetr Mladek * also taken in their write paths. 6350cd2440d6SPetr Mladek */ 6351cd2440d6SPetr Mladek printk_deferred_enter(); 6352cd2440d6SPetr Mladek 6353cd2440d6SPetr Mladek pr_info("pool %d:\n", pool->id); 6354cd2440d6SPetr Mladek sched_show_task(worker->task); 6355cd2440d6SPetr Mladek 6356cd2440d6SPetr Mladek printk_deferred_exit(); 6357cd2440d6SPetr Mladek } 6358cd2440d6SPetr Mladek } 6359cd2440d6SPetr Mladek 6360cd2440d6SPetr Mladek raw_spin_unlock_irqrestore(&pool->lock, flags); 6361cd2440d6SPetr Mladek } 6362cd2440d6SPetr Mladek 6363cd2440d6SPetr Mladek static void show_cpu_pools_hogs(void) 6364cd2440d6SPetr Mladek { 6365cd2440d6SPetr Mladek struct worker_pool *pool; 6366cd2440d6SPetr Mladek int pi; 6367cd2440d6SPetr Mladek 6368cd2440d6SPetr Mladek pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n"); 6369cd2440d6SPetr Mladek 6370cd2440d6SPetr Mladek rcu_read_lock(); 6371cd2440d6SPetr Mladek 6372cd2440d6SPetr Mladek for_each_pool(pool, pi) { 6373cd2440d6SPetr Mladek if (pool->cpu_stall) 6374cd2440d6SPetr Mladek show_cpu_pool_hog(pool); 6375cd2440d6SPetr Mladek 6376cd2440d6SPetr Mladek } 6377cd2440d6SPetr Mladek 6378cd2440d6SPetr Mladek rcu_read_unlock(); 6379cd2440d6SPetr Mladek } 6380cd2440d6SPetr Mladek 638182607adcSTejun Heo static void wq_watchdog_reset_touched(void) 638282607adcSTejun Heo { 638382607adcSTejun Heo int cpu; 638482607adcSTejun Heo 638582607adcSTejun Heo wq_watchdog_touched = jiffies; 638682607adcSTejun Heo for_each_possible_cpu(cpu) 638782607adcSTejun Heo per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; 638882607adcSTejun Heo } 638982607adcSTejun Heo 63905cd79d6aSKees Cook static void wq_watchdog_timer_fn(struct timer_list *unused) 639182607adcSTejun Heo { 639282607adcSTejun Heo unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; 639382607adcSTejun Heo bool lockup_detected = false; 6394cd2440d6SPetr Mladek bool cpu_pool_stall = false; 6395940d71c6SSergey Senozhatsky unsigned long now = jiffies; 639682607adcSTejun Heo struct worker_pool *pool; 639782607adcSTejun Heo int pi; 639882607adcSTejun Heo 639982607adcSTejun Heo if (!thresh) 640082607adcSTejun Heo return; 640182607adcSTejun Heo 640282607adcSTejun Heo rcu_read_lock(); 640382607adcSTejun Heo 640482607adcSTejun Heo for_each_pool(pool, pi) { 640582607adcSTejun Heo unsigned long pool_ts, touched, ts; 640682607adcSTejun Heo 6407cd2440d6SPetr Mladek pool->cpu_stall = false; 640882607adcSTejun Heo if (list_empty(&pool->worklist)) 640982607adcSTejun Heo continue; 641082607adcSTejun Heo 6411940d71c6SSergey Senozhatsky /* 6412940d71c6SSergey Senozhatsky * If a virtual machine is stopped by the host it can look to 6413940d71c6SSergey Senozhatsky * the watchdog like a stall. 6414940d71c6SSergey Senozhatsky */ 6415940d71c6SSergey Senozhatsky kvm_check_and_clear_guest_paused(); 6416940d71c6SSergey Senozhatsky 641782607adcSTejun Heo /* get the latest of pool and touched timestamps */ 641889e28ce6SWang Qing if (pool->cpu >= 0) 641989e28ce6SWang Qing touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu)); 642089e28ce6SWang Qing else 642182607adcSTejun Heo touched = READ_ONCE(wq_watchdog_touched); 642289e28ce6SWang Qing pool_ts = READ_ONCE(pool->watchdog_ts); 642382607adcSTejun Heo 642482607adcSTejun Heo if (time_after(pool_ts, touched)) 642582607adcSTejun Heo ts = pool_ts; 642682607adcSTejun Heo else 642782607adcSTejun Heo ts = touched; 642882607adcSTejun Heo 642982607adcSTejun Heo /* did we stall? */ 6430940d71c6SSergey Senozhatsky if (time_after(now, ts + thresh)) { 643182607adcSTejun Heo lockup_detected = true; 6432cd2440d6SPetr Mladek if (pool->cpu >= 0) { 6433cd2440d6SPetr Mladek pool->cpu_stall = true; 6434cd2440d6SPetr Mladek cpu_pool_stall = true; 6435cd2440d6SPetr Mladek } 643682607adcSTejun Heo pr_emerg("BUG: workqueue lockup - pool"); 643782607adcSTejun Heo pr_cont_pool_info(pool); 643882607adcSTejun Heo pr_cont(" stuck for %us!\n", 6439940d71c6SSergey Senozhatsky jiffies_to_msecs(now - pool_ts) / 1000); 644082607adcSTejun Heo } 6441cd2440d6SPetr Mladek 6442cd2440d6SPetr Mladek 644382607adcSTejun Heo } 644482607adcSTejun Heo 644582607adcSTejun Heo rcu_read_unlock(); 644682607adcSTejun Heo 644782607adcSTejun Heo if (lockup_detected) 644855df0933SImran Khan show_all_workqueues(); 644982607adcSTejun Heo 6450cd2440d6SPetr Mladek if (cpu_pool_stall) 6451cd2440d6SPetr Mladek show_cpu_pools_hogs(); 6452cd2440d6SPetr Mladek 645382607adcSTejun Heo wq_watchdog_reset_touched(); 645482607adcSTejun Heo mod_timer(&wq_watchdog_timer, jiffies + thresh); 645582607adcSTejun Heo } 645682607adcSTejun Heo 6457cb9d7fd5SVincent Whitchurch notrace void wq_watchdog_touch(int cpu) 645882607adcSTejun Heo { 645982607adcSTejun Heo if (cpu >= 0) 646082607adcSTejun Heo per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; 646189e28ce6SWang Qing 646282607adcSTejun Heo wq_watchdog_touched = jiffies; 646382607adcSTejun Heo } 646482607adcSTejun Heo 646582607adcSTejun Heo static void wq_watchdog_set_thresh(unsigned long thresh) 646682607adcSTejun Heo { 646782607adcSTejun Heo wq_watchdog_thresh = 0; 646882607adcSTejun Heo del_timer_sync(&wq_watchdog_timer); 646982607adcSTejun Heo 647082607adcSTejun Heo if (thresh) { 647182607adcSTejun Heo wq_watchdog_thresh = thresh; 647282607adcSTejun Heo wq_watchdog_reset_touched(); 647382607adcSTejun Heo mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ); 647482607adcSTejun Heo } 647582607adcSTejun Heo } 647682607adcSTejun Heo 647782607adcSTejun Heo static int wq_watchdog_param_set_thresh(const char *val, 647882607adcSTejun Heo const struct kernel_param *kp) 647982607adcSTejun Heo { 648082607adcSTejun Heo unsigned long thresh; 648182607adcSTejun Heo int ret; 648282607adcSTejun Heo 648382607adcSTejun Heo ret = kstrtoul(val, 0, &thresh); 648482607adcSTejun Heo if (ret) 648582607adcSTejun Heo return ret; 648682607adcSTejun Heo 648782607adcSTejun Heo if (system_wq) 648882607adcSTejun Heo wq_watchdog_set_thresh(thresh); 648982607adcSTejun Heo else 649082607adcSTejun Heo wq_watchdog_thresh = thresh; 649182607adcSTejun Heo 649282607adcSTejun Heo return 0; 649382607adcSTejun Heo } 649482607adcSTejun Heo 649582607adcSTejun Heo static const struct kernel_param_ops wq_watchdog_thresh_ops = { 649682607adcSTejun Heo .set = wq_watchdog_param_set_thresh, 649782607adcSTejun Heo .get = param_get_ulong, 649882607adcSTejun Heo }; 649982607adcSTejun Heo 650082607adcSTejun Heo module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, 650182607adcSTejun Heo 0644); 650282607adcSTejun Heo 650382607adcSTejun Heo static void wq_watchdog_init(void) 650482607adcSTejun Heo { 65055cd79d6aSKees Cook timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE); 650682607adcSTejun Heo wq_watchdog_set_thresh(wq_watchdog_thresh); 650782607adcSTejun Heo } 650882607adcSTejun Heo 650982607adcSTejun Heo #else /* CONFIG_WQ_WATCHDOG */ 651082607adcSTejun Heo 651182607adcSTejun Heo static inline void wq_watchdog_init(void) { } 651282607adcSTejun Heo 651382607adcSTejun Heo #endif /* CONFIG_WQ_WATCHDOG */ 651482607adcSTejun Heo 6515*b2c562a7STejun Heo static void __init restrict_unbound_cpumask(const char *name, const struct cpumask *mask) 6516*b2c562a7STejun Heo { 6517*b2c562a7STejun Heo if (!cpumask_intersects(wq_unbound_cpumask, mask)) { 6518*b2c562a7STejun Heo pr_warn("workqueue: Restricting unbound_cpumask (%*pb) with %s (%*pb) leaves no CPU, ignoring\n", 6519*b2c562a7STejun Heo cpumask_pr_args(wq_unbound_cpumask), name, cpumask_pr_args(mask)); 6520*b2c562a7STejun Heo return; 6521*b2c562a7STejun Heo } 6522*b2c562a7STejun Heo 6523*b2c562a7STejun Heo cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, mask); 6524*b2c562a7STejun Heo } 6525*b2c562a7STejun Heo 65263347fa09STejun Heo /** 65273347fa09STejun Heo * workqueue_init_early - early init for workqueue subsystem 65283347fa09STejun Heo * 65292930155bSTejun Heo * This is the first step of three-staged workqueue subsystem initialization and 65302930155bSTejun Heo * invoked as soon as the bare basics - memory allocation, cpumasks and idr are 65312930155bSTejun Heo * up. It sets up all the data structures and system workqueues and allows early 65322930155bSTejun Heo * boot code to create workqueues and queue/cancel work items. Actual work item 65332930155bSTejun Heo * execution starts only after kthreads can be created and scheduled right 65342930155bSTejun Heo * before early initcalls. 65353347fa09STejun Heo */ 65362333e829SYu Chen void __init workqueue_init_early(void) 65371da177e4SLinus Torvalds { 653884193c07STejun Heo struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_SYSTEM]; 65397a4e344cSTejun Heo int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; 65407a4e344cSTejun Heo int i, cpu; 6541c34056a3STejun Heo 654210cdb157SLai Jiangshan BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); 6543e904e6c2STejun Heo 6544b05a7928SFrederic Weisbecker BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); 6545*b2c562a7STejun Heo cpumask_copy(wq_unbound_cpumask, cpu_possible_mask); 6546*b2c562a7STejun Heo restrict_unbound_cpumask("HK_TYPE_WQ", housekeeping_cpumask(HK_TYPE_WQ)); 6547*b2c562a7STejun Heo restrict_unbound_cpumask("HK_TYPE_DOMAIN", housekeeping_cpumask(HK_TYPE_DOMAIN)); 6548ace3c549Stiozhang if (!cpumask_empty(&wq_cmdline_cpumask)) 6549*b2c562a7STejun Heo restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask); 6550ace3c549Stiozhang 6551e904e6c2STejun Heo pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); 6552e904e6c2STejun Heo 65532930155bSTejun Heo wq_update_pod_attrs_buf = alloc_workqueue_attrs(); 65542930155bSTejun Heo BUG_ON(!wq_update_pod_attrs_buf); 65552930155bSTejun Heo 655684193c07STejun Heo /* initialize WQ_AFFN_SYSTEM pods */ 655784193c07STejun Heo pt->pod_cpus = kcalloc(1, sizeof(pt->pod_cpus[0]), GFP_KERNEL); 655884193c07STejun Heo pt->pod_node = kcalloc(1, sizeof(pt->pod_node[0]), GFP_KERNEL); 655984193c07STejun Heo pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL); 656084193c07STejun Heo BUG_ON(!pt->pod_cpus || !pt->pod_node || !pt->cpu_pod); 656184193c07STejun Heo 656284193c07STejun Heo BUG_ON(!zalloc_cpumask_var_node(&pt->pod_cpus[0], GFP_KERNEL, NUMA_NO_NODE)); 656384193c07STejun Heo 656484193c07STejun Heo pt->nr_pods = 1; 656584193c07STejun Heo cpumask_copy(pt->pod_cpus[0], cpu_possible_mask); 656684193c07STejun Heo pt->pod_node[0] = NUMA_NO_NODE; 656784193c07STejun Heo pt->cpu_pod[0] = 0; 656884193c07STejun Heo 6569706026c2STejun Heo /* initialize CPU pools */ 657029c91e99STejun Heo for_each_possible_cpu(cpu) { 65714ce62e9eSTejun Heo struct worker_pool *pool; 65728b03ae3cSTejun Heo 65737a4e344cSTejun Heo i = 0; 6574f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 65757a4e344cSTejun Heo BUG_ON(init_worker_pool(pool)); 6576ec22ca5eSTejun Heo pool->cpu = cpu; 65777a4e344cSTejun Heo cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); 65789546b29eSTejun Heo cpumask_copy(pool->attrs->__pod_cpumask, cpumask_of(cpu)); 65797a4e344cSTejun Heo pool->attrs->nice = std_nice[i++]; 65808639ecebSTejun Heo pool->attrs->affn_strict = true; 6581f3f90ad4STejun Heo pool->node = cpu_to_node(cpu); 65827a4e344cSTejun Heo 65839daf9e67STejun Heo /* alloc pool ID */ 658468e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 65859daf9e67STejun Heo BUG_ON(worker_pool_assign_id(pool)); 658668e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 65874ce62e9eSTejun Heo } 65888b03ae3cSTejun Heo } 65898b03ae3cSTejun Heo 65908a2b7538STejun Heo /* create default unbound and ordered wq attrs */ 659129c91e99STejun Heo for (i = 0; i < NR_STD_WORKER_POOLS; i++) { 659229c91e99STejun Heo struct workqueue_attrs *attrs; 659329c91e99STejun Heo 6594be69d00dSThomas Gleixner BUG_ON(!(attrs = alloc_workqueue_attrs())); 659529c91e99STejun Heo attrs->nice = std_nice[i]; 659629c91e99STejun Heo unbound_std_wq_attrs[i] = attrs; 65978a2b7538STejun Heo 65988a2b7538STejun Heo /* 65998a2b7538STejun Heo * An ordered wq should have only one pwq as ordering is 66008a2b7538STejun Heo * guaranteed by max_active which is enforced by pwqs. 66018a2b7538STejun Heo */ 6602be69d00dSThomas Gleixner BUG_ON(!(attrs = alloc_workqueue_attrs())); 66038a2b7538STejun Heo attrs->nice = std_nice[i]; 6604af73f5c9STejun Heo attrs->ordered = true; 66058a2b7538STejun Heo ordered_wq_attrs[i] = attrs; 660629c91e99STejun Heo } 660729c91e99STejun Heo 6608d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 66091aabe902SJoonsoo Kim system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 6610d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 6611f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 6612636b927eSTejun Heo WQ_MAX_ACTIVE); 661324d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 661424d51addSTejun Heo WQ_FREEZABLE, 0); 66150668106cSViresh Kumar system_power_efficient_wq = alloc_workqueue("events_power_efficient", 66160668106cSViresh Kumar WQ_POWER_EFFICIENT, 0); 66170668106cSViresh Kumar system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", 66180668106cSViresh Kumar WQ_FREEZABLE | WQ_POWER_EFFICIENT, 66190668106cSViresh Kumar 0); 66201aabe902SJoonsoo Kim BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 66210668106cSViresh Kumar !system_unbound_wq || !system_freezable_wq || 66220668106cSViresh Kumar !system_power_efficient_wq || 66230668106cSViresh Kumar !system_freezable_power_efficient_wq); 66243347fa09STejun Heo } 66253347fa09STejun Heo 6626aa6fde93STejun Heo static void __init wq_cpu_intensive_thresh_init(void) 6627aa6fde93STejun Heo { 6628aa6fde93STejun Heo unsigned long thresh; 6629aa6fde93STejun Heo unsigned long bogo; 6630aa6fde93STejun Heo 6631dd64c873SZqiang pwq_release_worker = kthread_create_worker(0, "pool_workqueue_release"); 6632dd64c873SZqiang BUG_ON(IS_ERR(pwq_release_worker)); 6633dd64c873SZqiang 6634aa6fde93STejun Heo /* if the user set it to a specific value, keep it */ 6635aa6fde93STejun Heo if (wq_cpu_intensive_thresh_us != ULONG_MAX) 6636aa6fde93STejun Heo return; 6637aa6fde93STejun Heo 6638aa6fde93STejun Heo /* 6639aa6fde93STejun Heo * The default of 10ms is derived from the fact that most modern (as of 6640aa6fde93STejun Heo * 2023) processors can do a lot in 10ms and that it's just below what 6641aa6fde93STejun Heo * most consider human-perceivable. However, the kernel also runs on a 6642aa6fde93STejun Heo * lot slower CPUs including microcontrollers where the threshold is way 6643aa6fde93STejun Heo * too low. 6644aa6fde93STejun Heo * 6645aa6fde93STejun Heo * Let's scale up the threshold upto 1 second if BogoMips is below 4000. 6646aa6fde93STejun Heo * This is by no means accurate but it doesn't have to be. The mechanism 6647aa6fde93STejun Heo * is still useful even when the threshold is fully scaled up. Also, as 6648aa6fde93STejun Heo * the reports would usually be applicable to everyone, some machines 6649aa6fde93STejun Heo * operating on longer thresholds won't significantly diminish their 6650aa6fde93STejun Heo * usefulness. 6651aa6fde93STejun Heo */ 6652aa6fde93STejun Heo thresh = 10 * USEC_PER_MSEC; 6653aa6fde93STejun Heo 6654aa6fde93STejun Heo /* see init/calibrate.c for lpj -> BogoMIPS calculation */ 6655aa6fde93STejun Heo bogo = max_t(unsigned long, loops_per_jiffy / 500000 * HZ, 1); 6656aa6fde93STejun Heo if (bogo < 4000) 6657aa6fde93STejun Heo thresh = min_t(unsigned long, thresh * 4000 / bogo, USEC_PER_SEC); 6658aa6fde93STejun Heo 6659aa6fde93STejun Heo pr_debug("wq_cpu_intensive_thresh: lpj=%lu BogoMIPS=%lu thresh_us=%lu\n", 6660aa6fde93STejun Heo loops_per_jiffy, bogo, thresh); 6661aa6fde93STejun Heo 6662aa6fde93STejun Heo wq_cpu_intensive_thresh_us = thresh; 6663aa6fde93STejun Heo } 6664aa6fde93STejun Heo 66653347fa09STejun Heo /** 66663347fa09STejun Heo * workqueue_init - bring workqueue subsystem fully online 66673347fa09STejun Heo * 66682930155bSTejun Heo * This is the second step of three-staged workqueue subsystem initialization 66692930155bSTejun Heo * and invoked as soon as kthreads can be created and scheduled. Workqueues have 66702930155bSTejun Heo * been created and work items queued on them, but there are no kworkers 66712930155bSTejun Heo * executing the work items yet. Populate the worker pools with the initial 66722930155bSTejun Heo * workers and enable future kworker creations. 66733347fa09STejun Heo */ 66742333e829SYu Chen void __init workqueue_init(void) 66753347fa09STejun Heo { 66762186d9f9STejun Heo struct workqueue_struct *wq; 66773347fa09STejun Heo struct worker_pool *pool; 66783347fa09STejun Heo int cpu, bkt; 66793347fa09STejun Heo 6680aa6fde93STejun Heo wq_cpu_intensive_thresh_init(); 6681aa6fde93STejun Heo 66822186d9f9STejun Heo mutex_lock(&wq_pool_mutex); 66832186d9f9STejun Heo 66842930155bSTejun Heo /* 66852930155bSTejun Heo * Per-cpu pools created earlier could be missing node hint. Fix them 66862930155bSTejun Heo * up. Also, create a rescuer for workqueues that requested it. 66872930155bSTejun Heo */ 66882186d9f9STejun Heo for_each_possible_cpu(cpu) { 66892186d9f9STejun Heo for_each_cpu_worker_pool(pool, cpu) { 66902186d9f9STejun Heo pool->node = cpu_to_node(cpu); 66912186d9f9STejun Heo } 66922186d9f9STejun Heo } 66932186d9f9STejun Heo 669440c17f75STejun Heo list_for_each_entry(wq, &workqueues, list) { 669540c17f75STejun Heo WARN(init_rescuer(wq), 669640c17f75STejun Heo "workqueue: failed to create early rescuer for %s", 669740c17f75STejun Heo wq->name); 669840c17f75STejun Heo } 66992186d9f9STejun Heo 67002186d9f9STejun Heo mutex_unlock(&wq_pool_mutex); 67012186d9f9STejun Heo 67023347fa09STejun Heo /* create the initial workers */ 67033347fa09STejun Heo for_each_online_cpu(cpu) { 67043347fa09STejun Heo for_each_cpu_worker_pool(pool, cpu) { 67053347fa09STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 67063347fa09STejun Heo BUG_ON(!create_worker(pool)); 67073347fa09STejun Heo } 67083347fa09STejun Heo } 67093347fa09STejun Heo 67103347fa09STejun Heo hash_for_each(unbound_pool_hash, bkt, pool, hash_node) 67113347fa09STejun Heo BUG_ON(!create_worker(pool)); 67123347fa09STejun Heo 67133347fa09STejun Heo wq_online = true; 671482607adcSTejun Heo wq_watchdog_init(); 67151da177e4SLinus Torvalds } 6716c4f135d6STetsuo Handa 6717025e1684STejun Heo /* 6718025e1684STejun Heo * Initialize @pt by first initializing @pt->cpu_pod[] with pod IDs according to 6719025e1684STejun Heo * @cpu_shares_pod(). Each subset of CPUs that share a pod is assigned a unique 6720025e1684STejun Heo * and consecutive pod ID. The rest of @pt is initialized accordingly. 6721025e1684STejun Heo */ 6722025e1684STejun Heo static void __init init_pod_type(struct wq_pod_type *pt, 6723025e1684STejun Heo bool (*cpus_share_pod)(int, int)) 6724025e1684STejun Heo { 6725025e1684STejun Heo int cur, pre, cpu, pod; 6726025e1684STejun Heo 6727025e1684STejun Heo pt->nr_pods = 0; 6728025e1684STejun Heo 6729025e1684STejun Heo /* init @pt->cpu_pod[] according to @cpus_share_pod() */ 6730025e1684STejun Heo pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL); 6731025e1684STejun Heo BUG_ON(!pt->cpu_pod); 6732025e1684STejun Heo 6733025e1684STejun Heo for_each_possible_cpu(cur) { 6734025e1684STejun Heo for_each_possible_cpu(pre) { 6735025e1684STejun Heo if (pre >= cur) { 6736025e1684STejun Heo pt->cpu_pod[cur] = pt->nr_pods++; 6737025e1684STejun Heo break; 6738025e1684STejun Heo } 6739025e1684STejun Heo if (cpus_share_pod(cur, pre)) { 6740025e1684STejun Heo pt->cpu_pod[cur] = pt->cpu_pod[pre]; 6741025e1684STejun Heo break; 6742025e1684STejun Heo } 6743025e1684STejun Heo } 6744025e1684STejun Heo } 6745025e1684STejun Heo 6746025e1684STejun Heo /* init the rest to match @pt->cpu_pod[] */ 6747025e1684STejun Heo pt->pod_cpus = kcalloc(pt->nr_pods, sizeof(pt->pod_cpus[0]), GFP_KERNEL); 6748025e1684STejun Heo pt->pod_node = kcalloc(pt->nr_pods, sizeof(pt->pod_node[0]), GFP_KERNEL); 6749025e1684STejun Heo BUG_ON(!pt->pod_cpus || !pt->pod_node); 6750025e1684STejun Heo 6751025e1684STejun Heo for (pod = 0; pod < pt->nr_pods; pod++) 6752025e1684STejun Heo BUG_ON(!zalloc_cpumask_var(&pt->pod_cpus[pod], GFP_KERNEL)); 6753025e1684STejun Heo 6754025e1684STejun Heo for_each_possible_cpu(cpu) { 6755025e1684STejun Heo cpumask_set_cpu(cpu, pt->pod_cpus[pt->cpu_pod[cpu]]); 6756025e1684STejun Heo pt->pod_node[pt->cpu_pod[cpu]] = cpu_to_node(cpu); 6757025e1684STejun Heo } 6758025e1684STejun Heo } 6759025e1684STejun Heo 676063c5484eSTejun Heo static bool __init cpus_dont_share(int cpu0, int cpu1) 676163c5484eSTejun Heo { 676263c5484eSTejun Heo return false; 676363c5484eSTejun Heo } 676463c5484eSTejun Heo 676563c5484eSTejun Heo static bool __init cpus_share_smt(int cpu0, int cpu1) 676663c5484eSTejun Heo { 676763c5484eSTejun Heo #ifdef CONFIG_SCHED_SMT 676863c5484eSTejun Heo return cpumask_test_cpu(cpu0, cpu_smt_mask(cpu1)); 676963c5484eSTejun Heo #else 677063c5484eSTejun Heo return false; 677163c5484eSTejun Heo #endif 677263c5484eSTejun Heo } 677363c5484eSTejun Heo 6774025e1684STejun Heo static bool __init cpus_share_numa(int cpu0, int cpu1) 6775025e1684STejun Heo { 6776025e1684STejun Heo return cpu_to_node(cpu0) == cpu_to_node(cpu1); 6777025e1684STejun Heo } 6778025e1684STejun Heo 67792930155bSTejun Heo /** 67802930155bSTejun Heo * workqueue_init_topology - initialize CPU pods for unbound workqueues 67812930155bSTejun Heo * 67822930155bSTejun Heo * This is the third step of there-staged workqueue subsystem initialization and 67832930155bSTejun Heo * invoked after SMP and topology information are fully initialized. It 67842930155bSTejun Heo * initializes the unbound CPU pods accordingly. 67852930155bSTejun Heo */ 67862930155bSTejun Heo void __init workqueue_init_topology(void) 6787a86feae6STejun Heo { 67882930155bSTejun Heo struct workqueue_struct *wq; 6789025e1684STejun Heo int cpu; 6790a86feae6STejun Heo 679163c5484eSTejun Heo init_pod_type(&wq_pod_types[WQ_AFFN_CPU], cpus_dont_share); 679263c5484eSTejun Heo init_pod_type(&wq_pod_types[WQ_AFFN_SMT], cpus_share_smt); 679363c5484eSTejun Heo init_pod_type(&wq_pod_types[WQ_AFFN_CACHE], cpus_share_cache); 6794025e1684STejun Heo init_pod_type(&wq_pod_types[WQ_AFFN_NUMA], cpus_share_numa); 6795a86feae6STejun Heo 67962930155bSTejun Heo mutex_lock(&wq_pool_mutex); 6797a86feae6STejun Heo 6798a86feae6STejun Heo /* 67992930155bSTejun Heo * Workqueues allocated earlier would have all CPUs sharing the default 68002930155bSTejun Heo * worker pool. Explicitly call wq_update_pod() on all workqueue and CPU 68012930155bSTejun Heo * combinations to apply per-pod sharing. 68022930155bSTejun Heo */ 68032930155bSTejun Heo list_for_each_entry(wq, &workqueues, list) { 68042930155bSTejun Heo for_each_online_cpu(cpu) { 68052930155bSTejun Heo wq_update_pod(wq, cpu, cpu, true); 68062930155bSTejun Heo } 68072930155bSTejun Heo } 68082930155bSTejun Heo 68092930155bSTejun Heo mutex_unlock(&wq_pool_mutex); 6810a86feae6STejun Heo } 6811a86feae6STejun Heo 681220bdedafSTetsuo Handa void __warn_flushing_systemwide_wq(void) 681320bdedafSTetsuo Handa { 681420bdedafSTetsuo Handa pr_warn("WARNING: Flushing system-wide workqueues will be prohibited in near future.\n"); 681520bdedafSTetsuo Handa dump_stack(); 681620bdedafSTetsuo Handa } 6817c4f135d6STetsuo Handa EXPORT_SYMBOL(__warn_flushing_systemwide_wq); 6818ace3c549Stiozhang 6819ace3c549Stiozhang static int __init workqueue_unbound_cpus_setup(char *str) 6820ace3c549Stiozhang { 6821ace3c549Stiozhang if (cpulist_parse(str, &wq_cmdline_cpumask) < 0) { 6822ace3c549Stiozhang cpumask_clear(&wq_cmdline_cpumask); 6823ace3c549Stiozhang pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n"); 6824ace3c549Stiozhang } 6825ace3c549Stiozhang 6826ace3c549Stiozhang return 1; 6827ace3c549Stiozhang } 6828ace3c549Stiozhang __setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup); 6829