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> 55e22bee78STejun Heo 56ea138446STejun Heo #include "workqueue_internal.h" 571da177e4SLinus Torvalds 58c8e55f36STejun Heo enum { 59bc2ae0f5STejun Heo /* 6024647570STejun Heo * worker_pool flags 61bc2ae0f5STejun Heo * 6224647570STejun Heo * A bound pool is either associated or disassociated with its CPU. 63bc2ae0f5STejun Heo * While associated (!DISASSOCIATED), all workers are bound to the 64bc2ae0f5STejun Heo * CPU and none has %WORKER_UNBOUND set and concurrency management 65bc2ae0f5STejun Heo * is in effect. 66bc2ae0f5STejun Heo * 67bc2ae0f5STejun Heo * While DISASSOCIATED, the cpu may be offline and all workers have 68bc2ae0f5STejun Heo * %WORKER_UNBOUND set and concurrency management disabled, and may 6924647570STejun Heo * be executing on any CPU. The pool behaves as an unbound one. 70bc2ae0f5STejun Heo * 71bc3a1afcSTejun Heo * Note that DISASSOCIATED should be flipped only while holding 721258fae7STejun Heo * wq_pool_attach_mutex to avoid changing binding state while 734736cbf7SLai Jiangshan * worker_attach_to_pool() is in progress. 74bc2ae0f5STejun Heo */ 75692b4825STejun Heo POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */ 7624647570STejun Heo POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 77db7bccf4STejun Heo 78c8e55f36STejun Heo /* worker flags */ 79c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 80c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 81e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 82fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 83f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 84a9ab775bSTejun Heo WORKER_REBOUND = 1 << 8, /* worker was rebound */ 85e22bee78STejun Heo 86a9ab775bSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | 87a9ab775bSTejun Heo WORKER_UNBOUND | WORKER_REBOUND, 88db7bccf4STejun Heo 89e34cdddbSTejun Heo NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ 904ce62e9eSTejun Heo 9129c91e99STejun Heo UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ 92c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 93db7bccf4STejun Heo 94e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 95e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 96e22bee78STejun Heo 973233cdbdSTejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, 983233cdbdSTejun Heo /* call for help after 10ms 993233cdbdSTejun Heo (min two ticks) */ 100e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 101e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 1021da177e4SLinus Torvalds 1031da177e4SLinus Torvalds /* 104e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 1058698a745SDongsheng Yang * all cpus. Give MIN_NICE. 106e22bee78STejun Heo */ 1078698a745SDongsheng Yang RESCUER_NICE_LEVEL = MIN_NICE, 1088698a745SDongsheng Yang HIGHPRI_NICE_LEVEL = MIN_NICE, 109ecf6881fSTejun Heo 110ecf6881fSTejun Heo WQ_NAME_LEN = 24, 111c8e55f36STejun Heo }; 112c8e55f36STejun Heo 1131da177e4SLinus Torvalds /* 1144690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 1154690c4abSTejun Heo * 116e41e704bSTejun Heo * I: Modifiable by initialization/destruction paths and read-only for 117e41e704bSTejun Heo * everyone else. 1184690c4abSTejun Heo * 119e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 120e22bee78STejun Heo * only be modified and accessed from the local cpu. 121e22bee78STejun Heo * 122d565ed63STejun Heo * L: pool->lock protected. Access with pool->lock held. 1234690c4abSTejun Heo * 124d565ed63STejun Heo * X: During normal operation, modification requires pool->lock and should 125d565ed63STejun Heo * be done only from local cpu. Either disabling preemption on local 126d565ed63STejun Heo * cpu or grabbing pool->lock is enough for read access. If 127d565ed63STejun Heo * POOL_DISASSOCIATED is set, it's identical to L. 128e22bee78STejun Heo * 1291258fae7STejun Heo * A: wq_pool_attach_mutex protected. 130822d8405STejun Heo * 13168e13a67SLai Jiangshan * PL: wq_pool_mutex protected. 13276af4d93STejun Heo * 13324acfb71SThomas Gleixner * PR: wq_pool_mutex protected for writes. RCU protected for reads. 1345bcab335STejun Heo * 1355b95e1afSLai Jiangshan * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. 1365b95e1afSLai Jiangshan * 1375b95e1afSLai Jiangshan * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or 13824acfb71SThomas Gleixner * RCU for reads. 1395b95e1afSLai Jiangshan * 1403c25a55dSLai Jiangshan * WQ: wq->mutex protected. 1413c25a55dSLai Jiangshan * 14224acfb71SThomas Gleixner * WR: wq->mutex protected for writes. RCU protected for reads. 1432e109a28STejun Heo * 1442e109a28STejun Heo * MD: wq_mayday_lock protected. 145cd2440d6SPetr Mladek * 146cd2440d6SPetr Mladek * WD: Used internally by the watchdog. 1474690c4abSTejun Heo */ 1484690c4abSTejun Heo 1492eaebdb3STejun Heo /* struct worker is defined in workqueue_internal.h */ 150c34056a3STejun Heo 151bd7bdd43STejun Heo struct worker_pool { 152a9b8a985SSebastian Andrzej Siewior raw_spinlock_t lock; /* the pool lock */ 153d84ff051STejun Heo int cpu; /* I: the associated cpu */ 154f3f90ad4STejun Heo int node; /* I: the associated node ID */ 1559daf9e67STejun Heo int id; /* I: pool ID */ 15611ebea50STejun Heo unsigned int flags; /* X: flags */ 157bd7bdd43STejun Heo 15882607adcSTejun Heo unsigned long watchdog_ts; /* L: watchdog timestamp */ 159cd2440d6SPetr Mladek bool cpu_stall; /* WD: stalled cpu bound pool */ 16082607adcSTejun Heo 161bc35f7efSLai Jiangshan /* 162bc35f7efSLai Jiangshan * The counter is incremented in a process context on the associated CPU 163bc35f7efSLai Jiangshan * w/ preemption disabled, and decremented or reset in the same context 164bc35f7efSLai Jiangshan * but w/ pool->lock held. The readers grab pool->lock and are 165bc35f7efSLai Jiangshan * guaranteed to see if the counter reached zero. 166bc35f7efSLai Jiangshan */ 167bc35f7efSLai Jiangshan int nr_running; 16884f91c62SLai Jiangshan 169bd7bdd43STejun Heo struct list_head worklist; /* L: list of pending works */ 170ea1abd61SLai Jiangshan 1715826cc8fSLai Jiangshan int nr_workers; /* L: total number of workers */ 1725826cc8fSLai Jiangshan int nr_idle; /* L: currently idle workers */ 173bd7bdd43STejun Heo 1742c1f1a91SLai Jiangshan struct list_head idle_list; /* L: list of idle workers */ 175bd7bdd43STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 1763f959aa3SValentin Schneider struct work_struct idle_cull_work; /* L: worker idle cleanup */ 1773f959aa3SValentin Schneider 178bd7bdd43STejun Heo struct timer_list mayday_timer; /* L: SOS timer for workers */ 179bd7bdd43STejun Heo 180c5aa87bbSTejun Heo /* a workers is either on busy_hash or idle_list, or the manager */ 181c9e7cf27STejun Heo DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); 182c9e7cf27STejun Heo /* L: hash of busy workers */ 183c9e7cf27STejun Heo 1842607d7a6STejun Heo struct worker *manager; /* L: purely informational */ 18592f9c5c4SLai Jiangshan struct list_head workers; /* A: attached workers */ 186e02b9312SValentin Schneider struct list_head dying_workers; /* A: workers about to die */ 18760f5a4bcSLai Jiangshan struct completion *detach_completion; /* all workers detached */ 188e19e397aSTejun Heo 1897cda9aaeSLai Jiangshan struct ida worker_ida; /* worker IDs for task name */ 190e19e397aSTejun Heo 1917a4e344cSTejun Heo struct workqueue_attrs *attrs; /* I: worker attributes */ 19268e13a67SLai Jiangshan struct hlist_node hash_node; /* PL: unbound_pool_hash node */ 19368e13a67SLai Jiangshan int refcnt; /* PL: refcnt for unbound pools */ 1947a4e344cSTejun Heo 195e19e397aSTejun Heo /* 19624acfb71SThomas Gleixner * Destruction of pool is RCU protected to allow dereferences 19729c91e99STejun Heo * from get_work_pool(). 19829c91e99STejun Heo */ 19929c91e99STejun Heo struct rcu_head rcu; 20084f91c62SLai Jiangshan }; 2018b03ae3cSTejun Heo 2028b03ae3cSTejun Heo /* 203112202d9STejun Heo * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS 204112202d9STejun Heo * of work_struct->data are used for flags and the remaining high bits 205112202d9STejun Heo * point to the pwq; thus, pwqs need to be aligned at two's power of the 206112202d9STejun Heo * number of flag bits. 2071da177e4SLinus Torvalds */ 208112202d9STejun Heo struct pool_workqueue { 209bd7bdd43STejun Heo struct worker_pool *pool; /* I: the associated pool */ 2104690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 21173f53c4aSTejun Heo int work_color; /* L: current color */ 21273f53c4aSTejun Heo int flush_color; /* L: flushing color */ 2138864b4e5STejun Heo int refcnt; /* L: reference count */ 21473f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 21573f53c4aSTejun Heo /* L: nr of in_flight works */ 216018f3a13SLai Jiangshan 217018f3a13SLai Jiangshan /* 218018f3a13SLai Jiangshan * nr_active management and WORK_STRUCT_INACTIVE: 219018f3a13SLai Jiangshan * 220018f3a13SLai Jiangshan * When pwq->nr_active >= max_active, new work item is queued to 221018f3a13SLai Jiangshan * pwq->inactive_works instead of pool->worklist and marked with 222018f3a13SLai Jiangshan * WORK_STRUCT_INACTIVE. 223018f3a13SLai Jiangshan * 224018f3a13SLai Jiangshan * All work items marked with WORK_STRUCT_INACTIVE do not participate 225018f3a13SLai Jiangshan * in pwq->nr_active and all work items in pwq->inactive_works are 226018f3a13SLai Jiangshan * marked with WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE 227018f3a13SLai Jiangshan * work items are in pwq->inactive_works. Some of them are ready to 228018f3a13SLai Jiangshan * run in pool->worklist or worker->scheduled. Those work itmes are 229018f3a13SLai Jiangshan * only struct wq_barrier which is used for flush_work() and should 230018f3a13SLai Jiangshan * not participate in pwq->nr_active. For non-barrier work item, it 231018f3a13SLai Jiangshan * is marked with WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works. 232018f3a13SLai Jiangshan */ 2331e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 234a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 235f97a4a1aSLai Jiangshan struct list_head inactive_works; /* L: inactive works */ 2363c25a55dSLai Jiangshan struct list_head pwqs_node; /* WR: node on wq->pwqs */ 2372e109a28STejun Heo struct list_head mayday_node; /* MD: node on wq->maydays */ 2388864b4e5STejun Heo 2398864b4e5STejun Heo /* 2408864b4e5STejun Heo * Release of unbound pwq is punted to system_wq. See put_pwq() 2418864b4e5STejun Heo * and pwq_unbound_release_workfn() for details. pool_workqueue 24224acfb71SThomas Gleixner * itself is also RCU protected so that the first pwq can be 243b09f4fd3SLai Jiangshan * determined without grabbing wq->mutex. 2448864b4e5STejun Heo */ 2458864b4e5STejun Heo struct work_struct unbound_release_work; 2468864b4e5STejun Heo struct rcu_head rcu; 247e904e6c2STejun Heo } __aligned(1 << WORK_STRUCT_FLAG_BITS); 2481da177e4SLinus Torvalds 2491da177e4SLinus Torvalds /* 25073f53c4aSTejun Heo * Structure used to wait for workqueue flush. 25173f53c4aSTejun Heo */ 25273f53c4aSTejun Heo struct wq_flusher { 2533c25a55dSLai Jiangshan struct list_head list; /* WQ: list of flushers */ 2543c25a55dSLai Jiangshan int flush_color; /* WQ: flush color waiting for */ 25573f53c4aSTejun Heo struct completion done; /* flush completion */ 25673f53c4aSTejun Heo }; 2571da177e4SLinus Torvalds 258226223abSTejun Heo struct wq_device; 259226223abSTejun Heo 26073f53c4aSTejun Heo /* 261c5aa87bbSTejun Heo * The externally visible workqueue. It relays the issued work items to 262c5aa87bbSTejun Heo * the appropriate worker_pool through its pool_workqueues. 2631da177e4SLinus Torvalds */ 2641da177e4SLinus Torvalds struct workqueue_struct { 2653c25a55dSLai Jiangshan struct list_head pwqs; /* WR: all pwqs of this wq */ 266e2dca7adSTejun Heo struct list_head list; /* PR: list of all workqueues */ 26773f53c4aSTejun Heo 2683c25a55dSLai Jiangshan struct mutex mutex; /* protects this wq */ 2693c25a55dSLai Jiangshan int work_color; /* WQ: current work color */ 2703c25a55dSLai Jiangshan int flush_color; /* WQ: current flush color */ 271112202d9STejun Heo atomic_t nr_pwqs_to_flush; /* flush in progress */ 2723c25a55dSLai Jiangshan struct wq_flusher *first_flusher; /* WQ: first flusher */ 2733c25a55dSLai Jiangshan struct list_head flusher_queue; /* WQ: flush waiters */ 2743c25a55dSLai Jiangshan struct list_head flusher_overflow; /* WQ: flush overflow list */ 27573f53c4aSTejun Heo 2762e109a28STejun Heo struct list_head maydays; /* MD: pwqs requesting rescue */ 27730ae2fc0STejun Heo struct worker *rescuer; /* MD: rescue worker */ 278e22bee78STejun Heo 27987fc741eSLai Jiangshan int nr_drainers; /* WQ: drain in progress */ 280a357fc03SLai Jiangshan int saved_max_active; /* WQ: saved pwq max_active */ 281226223abSTejun Heo 2825b95e1afSLai Jiangshan struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ 2835b95e1afSLai Jiangshan struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */ 2846029a918STejun Heo 285226223abSTejun Heo #ifdef CONFIG_SYSFS 286226223abSTejun Heo struct wq_device *wq_dev; /* I: for sysfs interface */ 287226223abSTejun Heo #endif 2884e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 289669de8bdSBart Van Assche char *lock_name; 290669de8bdSBart Van Assche struct lock_class_key key; 2914e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2924e6045f1SJohannes Berg #endif 293ecf6881fSTejun Heo char name[WQ_NAME_LEN]; /* I: workqueue name */ 2942728fd2fSTejun Heo 295e2dca7adSTejun Heo /* 29624acfb71SThomas Gleixner * Destruction of workqueue_struct is RCU protected to allow walking 29724acfb71SThomas Gleixner * the workqueues list without grabbing wq_pool_mutex. 298e2dca7adSTejun Heo * This is used to dump all workqueues from sysrq. 299e2dca7adSTejun Heo */ 300e2dca7adSTejun Heo struct rcu_head rcu; 301e2dca7adSTejun Heo 3022728fd2fSTejun Heo /* hot fields used during command issue, aligned to cacheline */ 3032728fd2fSTejun Heo unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ 3042728fd2fSTejun Heo struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ 3055b95e1afSLai Jiangshan struct pool_workqueue __rcu *numa_pwq_tbl[]; /* PWR: unbound pwqs indexed by node */ 3061da177e4SLinus Torvalds }; 3071da177e4SLinus Torvalds 308e904e6c2STejun Heo static struct kmem_cache *pwq_cache; 309e904e6c2STejun Heo 310bce90380STejun Heo static cpumask_var_t *wq_numa_possible_cpumask; 311bce90380STejun Heo /* possible CPUs of each node */ 312bce90380STejun Heo 313d55262c4STejun Heo static bool wq_disable_numa; 314d55262c4STejun Heo module_param_named(disable_numa, wq_disable_numa, bool, 0444); 315d55262c4STejun Heo 316cee22a15SViresh Kumar /* see the comment above the definition of WQ_POWER_EFFICIENT */ 317552f530cSLuis R. Rodriguez static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); 318cee22a15SViresh Kumar module_param_named(power_efficient, wq_power_efficient, bool, 0444); 319cee22a15SViresh Kumar 320863b710bSTejun Heo static bool wq_online; /* can kworkers be created yet? */ 3213347fa09STejun Heo 322bce90380STejun Heo static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ 323bce90380STejun Heo 3244c16bd32STejun Heo /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ 3254c16bd32STejun Heo static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; 3264c16bd32STejun Heo 32768e13a67SLai Jiangshan static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ 3281258fae7STejun Heo static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ 329a9b8a985SSebastian Andrzej Siewior static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ 330d8bb65abSSebastian Andrzej Siewior /* wait for manager to go away */ 331d8bb65abSSebastian Andrzej Siewior static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait); 3325bcab335STejun Heo 333e2dca7adSTejun Heo static LIST_HEAD(workqueues); /* PR: list of all workqueues */ 33468e13a67SLai Jiangshan static bool workqueue_freezing; /* PL: have wqs started freezing? */ 3357d19c5ceSTejun Heo 33699c621efSLai Jiangshan /* PL&A: allowable cpus for unbound wqs and work items */ 337ef557180SMike Galbraith static cpumask_var_t wq_unbound_cpumask; 338ef557180SMike Galbraith 339ef557180SMike Galbraith /* CPU where unbound work was last round robin scheduled from this CPU */ 340ef557180SMike Galbraith static DEFINE_PER_CPU(int, wq_rr_cpu_last); 341b05a7928SFrederic Weisbecker 342f303fccbSTejun Heo /* 343f303fccbSTejun Heo * Local execution of unbound work items is no longer guaranteed. The 344f303fccbSTejun Heo * following always forces round-robin CPU selection on unbound work items 345f303fccbSTejun Heo * to uncover usages which depend on it. 346f303fccbSTejun Heo */ 347f303fccbSTejun Heo #ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU 348f303fccbSTejun Heo static bool wq_debug_force_rr_cpu = true; 349f303fccbSTejun Heo #else 350f303fccbSTejun Heo static bool wq_debug_force_rr_cpu = false; 351f303fccbSTejun Heo #endif 352f303fccbSTejun Heo module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); 353f303fccbSTejun Heo 3547d19c5ceSTejun Heo /* the per-cpu worker pools */ 35525528213SPeter Zijlstra static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); 3567d19c5ceSTejun Heo 35768e13a67SLai Jiangshan static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ 3587d19c5ceSTejun Heo 35968e13a67SLai Jiangshan /* PL: hash of all unbound pools keyed by pool->attrs */ 36029c91e99STejun Heo static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); 36129c91e99STejun Heo 362c5aa87bbSTejun Heo /* I: attributes used when instantiating standard unbound pools on demand */ 36329c91e99STejun Heo static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; 36429c91e99STejun Heo 3658a2b7538STejun Heo /* I: attributes used when instantiating ordered pools on demand */ 3668a2b7538STejun Heo static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; 3678a2b7538STejun Heo 368d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 369ad7b1f84SMarc Dionne EXPORT_SYMBOL(system_wq); 370044c782cSValentin Ilie struct workqueue_struct *system_highpri_wq __read_mostly; 3711aabe902SJoonsoo Kim EXPORT_SYMBOL_GPL(system_highpri_wq); 372044c782cSValentin Ilie struct workqueue_struct *system_long_wq __read_mostly; 373d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 374044c782cSValentin Ilie struct workqueue_struct *system_unbound_wq __read_mostly; 375f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 376044c782cSValentin Ilie struct workqueue_struct *system_freezable_wq __read_mostly; 37724d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 3780668106cSViresh Kumar struct workqueue_struct *system_power_efficient_wq __read_mostly; 3790668106cSViresh Kumar EXPORT_SYMBOL_GPL(system_power_efficient_wq); 3800668106cSViresh Kumar struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; 3810668106cSViresh Kumar EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); 382d320c038STejun Heo 3837d19c5ceSTejun Heo static int worker_thread(void *__worker); 3846ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq); 385c29eb853STejun Heo static void show_pwq(struct pool_workqueue *pwq); 38655df0933SImran Khan static void show_one_worker_pool(struct worker_pool *pool); 3877d19c5ceSTejun Heo 38897bd2347STejun Heo #define CREATE_TRACE_POINTS 38997bd2347STejun Heo #include <trace/events/workqueue.h> 39097bd2347STejun Heo 39168e13a67SLai Jiangshan #define assert_rcu_or_pool_mutex() \ 39224acfb71SThomas Gleixner RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ 393f78f5b90SPaul E. McKenney !lockdep_is_held(&wq_pool_mutex), \ 39424acfb71SThomas Gleixner "RCU or wq_pool_mutex should be held") 3955bcab335STejun Heo 3965b95e1afSLai Jiangshan #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \ 39724acfb71SThomas Gleixner RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ 398f78f5b90SPaul E. McKenney !lockdep_is_held(&wq->mutex) && \ 399f78f5b90SPaul E. McKenney !lockdep_is_held(&wq_pool_mutex), \ 40024acfb71SThomas Gleixner "RCU, wq->mutex or wq_pool_mutex should be held") 4015b95e1afSLai Jiangshan 402f02ae73aSTejun Heo #define for_each_cpu_worker_pool(pool, cpu) \ 403f02ae73aSTejun Heo for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ 404f02ae73aSTejun Heo (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ 4057a62c2c8STejun Heo (pool)++) 4064ce62e9eSTejun Heo 40749e3cf44STejun Heo /** 40817116969STejun Heo * for_each_pool - iterate through all worker_pools in the system 40917116969STejun Heo * @pool: iteration cursor 410611c92a0STejun Heo * @pi: integer used for iteration 411fa1b54e6STejun Heo * 41224acfb71SThomas Gleixner * This must be called either with wq_pool_mutex held or RCU read 41368e13a67SLai Jiangshan * locked. If the pool needs to be used beyond the locking in effect, the 41468e13a67SLai Jiangshan * caller is responsible for guaranteeing that the pool stays online. 415fa1b54e6STejun Heo * 416fa1b54e6STejun Heo * The if/else clause exists only for the lockdep assertion and can be 417fa1b54e6STejun Heo * ignored. 41817116969STejun Heo */ 419611c92a0STejun Heo #define for_each_pool(pool, pi) \ 420611c92a0STejun Heo idr_for_each_entry(&worker_pool_idr, pool, pi) \ 42168e13a67SLai Jiangshan if (({ assert_rcu_or_pool_mutex(); false; })) { } \ 422fa1b54e6STejun Heo else 42317116969STejun Heo 42417116969STejun Heo /** 425822d8405STejun Heo * for_each_pool_worker - iterate through all workers of a worker_pool 426822d8405STejun Heo * @worker: iteration cursor 427822d8405STejun Heo * @pool: worker_pool to iterate workers of 428822d8405STejun Heo * 4291258fae7STejun Heo * This must be called with wq_pool_attach_mutex. 430822d8405STejun Heo * 431822d8405STejun Heo * The if/else clause exists only for the lockdep assertion and can be 432822d8405STejun Heo * ignored. 433822d8405STejun Heo */ 434da028469SLai Jiangshan #define for_each_pool_worker(worker, pool) \ 435da028469SLai Jiangshan list_for_each_entry((worker), &(pool)->workers, node) \ 4361258fae7STejun Heo if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \ 437822d8405STejun Heo else 438822d8405STejun Heo 439822d8405STejun Heo /** 44049e3cf44STejun Heo * for_each_pwq - iterate through all pool_workqueues of the specified workqueue 44149e3cf44STejun Heo * @pwq: iteration cursor 44249e3cf44STejun Heo * @wq: the target workqueue 44376af4d93STejun Heo * 44424acfb71SThomas Gleixner * This must be called either with wq->mutex held or RCU read locked. 445794b18bcSTejun Heo * If the pwq needs to be used beyond the locking in effect, the caller is 446794b18bcSTejun Heo * responsible for guaranteeing that the pwq stays online. 44776af4d93STejun Heo * 44876af4d93STejun Heo * The if/else clause exists only for the lockdep assertion and can be 44976af4d93STejun Heo * ignored. 45049e3cf44STejun Heo */ 45149e3cf44STejun Heo #define for_each_pwq(pwq, wq) \ 45249e9d1a9SSebastian Andrzej Siewior list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \ 4535a644662SJoel Fernandes (Google) lockdep_is_held(&(wq->mutex))) 454f3421797STejun Heo 455dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 456dc186ad7SThomas Gleixner 457f9e62f31SStephen Boyd static const struct debug_obj_descr work_debug_descr; 458dc186ad7SThomas Gleixner 45999777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 46099777288SStanislaw Gruszka { 46199777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 46299777288SStanislaw Gruszka } 46399777288SStanislaw Gruszka 464b9fdac7fSDu, Changbin static bool work_is_static_object(void *addr) 465b9fdac7fSDu, Changbin { 466b9fdac7fSDu, Changbin struct work_struct *work = addr; 467b9fdac7fSDu, Changbin 468b9fdac7fSDu, Changbin return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work)); 469b9fdac7fSDu, Changbin } 470b9fdac7fSDu, Changbin 471dc186ad7SThomas Gleixner /* 472dc186ad7SThomas Gleixner * fixup_init is called when: 473dc186ad7SThomas Gleixner * - an active object is initialized 474dc186ad7SThomas Gleixner */ 47502a982a6SDu, Changbin static bool work_fixup_init(void *addr, enum debug_obj_state state) 476dc186ad7SThomas Gleixner { 477dc186ad7SThomas Gleixner struct work_struct *work = addr; 478dc186ad7SThomas Gleixner 479dc186ad7SThomas Gleixner switch (state) { 480dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 481dc186ad7SThomas Gleixner cancel_work_sync(work); 482dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 48302a982a6SDu, Changbin return true; 484dc186ad7SThomas Gleixner default: 48502a982a6SDu, Changbin return false; 486dc186ad7SThomas Gleixner } 487dc186ad7SThomas Gleixner } 488dc186ad7SThomas Gleixner 489dc186ad7SThomas Gleixner /* 490dc186ad7SThomas Gleixner * fixup_free is called when: 491dc186ad7SThomas Gleixner * - an active object is freed 492dc186ad7SThomas Gleixner */ 49302a982a6SDu, Changbin static bool work_fixup_free(void *addr, enum debug_obj_state state) 494dc186ad7SThomas Gleixner { 495dc186ad7SThomas Gleixner struct work_struct *work = addr; 496dc186ad7SThomas Gleixner 497dc186ad7SThomas Gleixner switch (state) { 498dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 499dc186ad7SThomas Gleixner cancel_work_sync(work); 500dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 50102a982a6SDu, Changbin return true; 502dc186ad7SThomas Gleixner default: 50302a982a6SDu, Changbin return false; 504dc186ad7SThomas Gleixner } 505dc186ad7SThomas Gleixner } 506dc186ad7SThomas Gleixner 507f9e62f31SStephen Boyd static const struct debug_obj_descr work_debug_descr = { 508dc186ad7SThomas Gleixner .name = "work_struct", 50999777288SStanislaw Gruszka .debug_hint = work_debug_hint, 510b9fdac7fSDu, Changbin .is_static_object = work_is_static_object, 511dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 512dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 513dc186ad7SThomas Gleixner }; 514dc186ad7SThomas Gleixner 515dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 516dc186ad7SThomas Gleixner { 517dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 518dc186ad7SThomas Gleixner } 519dc186ad7SThomas Gleixner 520dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 521dc186ad7SThomas Gleixner { 522dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 523dc186ad7SThomas Gleixner } 524dc186ad7SThomas Gleixner 525dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 526dc186ad7SThomas Gleixner { 527dc186ad7SThomas Gleixner if (onstack) 528dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 529dc186ad7SThomas Gleixner else 530dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 531dc186ad7SThomas Gleixner } 532dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 533dc186ad7SThomas Gleixner 534dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 535dc186ad7SThomas Gleixner { 536dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 537dc186ad7SThomas Gleixner } 538dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 539dc186ad7SThomas Gleixner 540ea2e64f2SThomas Gleixner void destroy_delayed_work_on_stack(struct delayed_work *work) 541ea2e64f2SThomas Gleixner { 542ea2e64f2SThomas Gleixner destroy_timer_on_stack(&work->timer); 543ea2e64f2SThomas Gleixner debug_object_free(&work->work, &work_debug_descr); 544ea2e64f2SThomas Gleixner } 545ea2e64f2SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); 546ea2e64f2SThomas Gleixner 547dc186ad7SThomas Gleixner #else 548dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 549dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 550dc186ad7SThomas Gleixner #endif 551dc186ad7SThomas Gleixner 5524e8b22bdSLi Bin /** 55367dc8325SCai Huoqing * worker_pool_assign_id - allocate ID and assign it to @pool 5544e8b22bdSLi Bin * @pool: the pool pointer of interest 5554e8b22bdSLi Bin * 5564e8b22bdSLi Bin * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned 5574e8b22bdSLi Bin * successfully, -errno on failure. 5584e8b22bdSLi Bin */ 5599daf9e67STejun Heo static int worker_pool_assign_id(struct worker_pool *pool) 5609daf9e67STejun Heo { 5619daf9e67STejun Heo int ret; 5629daf9e67STejun Heo 56368e13a67SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 5645bcab335STejun Heo 5654e8b22bdSLi Bin ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, 5664e8b22bdSLi Bin GFP_KERNEL); 567229641a6STejun Heo if (ret >= 0) { 568e68035fbSTejun Heo pool->id = ret; 569229641a6STejun Heo return 0; 570229641a6STejun Heo } 5719daf9e67STejun Heo return ret; 5729daf9e67STejun Heo } 5739daf9e67STejun Heo 57476af4d93STejun Heo /** 575df2d5ae4STejun Heo * unbound_pwq_by_node - return the unbound pool_workqueue for the given node 576df2d5ae4STejun Heo * @wq: the target workqueue 577df2d5ae4STejun Heo * @node: the node ID 578df2d5ae4STejun Heo * 57924acfb71SThomas Gleixner * This must be called with any of wq_pool_mutex, wq->mutex or RCU 5805b95e1afSLai Jiangshan * read locked. 581df2d5ae4STejun Heo * If the pwq needs to be used beyond the locking in effect, the caller is 582df2d5ae4STejun Heo * responsible for guaranteeing that the pwq stays online. 583d185af30SYacine Belkadi * 584d185af30SYacine Belkadi * Return: The unbound pool_workqueue for @node. 585df2d5ae4STejun Heo */ 586df2d5ae4STejun Heo static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, 587df2d5ae4STejun Heo int node) 588df2d5ae4STejun Heo { 5895b95e1afSLai Jiangshan assert_rcu_or_wq_mutex_or_pool_mutex(wq); 590d6e022f1STejun Heo 591d6e022f1STejun Heo /* 592d6e022f1STejun Heo * XXX: @node can be NUMA_NO_NODE if CPU goes offline while a 593d6e022f1STejun Heo * delayed item is pending. The plan is to keep CPU -> NODE 594d6e022f1STejun Heo * mapping valid and stable across CPU on/offlines. Once that 595d6e022f1STejun Heo * happens, this workaround can be removed. 596d6e022f1STejun Heo */ 597d6e022f1STejun Heo if (unlikely(node == NUMA_NO_NODE)) 598d6e022f1STejun Heo return wq->dfl_pwq; 599d6e022f1STejun Heo 600df2d5ae4STejun Heo return rcu_dereference_raw(wq->numa_pwq_tbl[node]); 601df2d5ae4STejun Heo } 602df2d5ae4STejun Heo 60373f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 60473f53c4aSTejun Heo { 60573f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 60673f53c4aSTejun Heo } 60773f53c4aSTejun Heo 608c4560c2cSLai Jiangshan static int get_work_color(unsigned long work_data) 60973f53c4aSTejun Heo { 610c4560c2cSLai Jiangshan return (work_data >> WORK_STRUCT_COLOR_SHIFT) & 61173f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 61273f53c4aSTejun Heo } 61373f53c4aSTejun Heo 61473f53c4aSTejun Heo static int work_next_color(int color) 61573f53c4aSTejun Heo { 61673f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 617a848e3b6SOleg Nesterov } 618a848e3b6SOleg Nesterov 6194594bf15SDavid Howells /* 620112202d9STejun Heo * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data 621112202d9STejun Heo * contain the pointer to the queued pwq. Once execution starts, the flag 6227c3eed5cSTejun Heo * is cleared and the high bits contain OFFQ flags and pool ID. 6237a22ad75STejun Heo * 624112202d9STejun Heo * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() 625112202d9STejun Heo * and clear_work_data() can be used to set the pwq, pool or clear 626bbb68dfaSTejun Heo * work->data. These functions should only be called while the work is 627bbb68dfaSTejun Heo * owned - ie. while the PENDING bit is set. 6287a22ad75STejun Heo * 629112202d9STejun Heo * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq 6307c3eed5cSTejun Heo * corresponding to a work. Pool is available once the work has been 631112202d9STejun Heo * queued anywhere after initialization until it is sync canceled. pwq is 6327c3eed5cSTejun Heo * available only while the work item is queued. 633bbb68dfaSTejun Heo * 634bbb68dfaSTejun Heo * %WORK_OFFQ_CANCELING is used to mark a work item which is being 635bbb68dfaSTejun Heo * canceled. While being canceled, a work item may have its PENDING set 636bbb68dfaSTejun Heo * but stay off timer and worklist for arbitrarily long and nobody should 637bbb68dfaSTejun Heo * try to steal the PENDING bit. 6384594bf15SDavid Howells */ 6397a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 6407a22ad75STejun Heo unsigned long flags) 6417a22ad75STejun Heo { 6426183c009STejun Heo WARN_ON_ONCE(!work_pending(work)); 6437a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 6447a22ad75STejun Heo } 6457a22ad75STejun Heo 646112202d9STejun Heo static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, 6474690c4abSTejun Heo unsigned long extra_flags) 648365970a1SDavid Howells { 649112202d9STejun Heo set_work_data(work, (unsigned long)pwq, 650112202d9STejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); 651365970a1SDavid Howells } 652365970a1SDavid Howells 6534468a00fSLai Jiangshan static void set_work_pool_and_keep_pending(struct work_struct *work, 6544468a00fSLai Jiangshan int pool_id) 6554468a00fSLai Jiangshan { 6564468a00fSLai Jiangshan set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 6574468a00fSLai Jiangshan WORK_STRUCT_PENDING); 6584468a00fSLai Jiangshan } 6594468a00fSLai Jiangshan 6607c3eed5cSTejun Heo static void set_work_pool_and_clear_pending(struct work_struct *work, 6617c3eed5cSTejun Heo int pool_id) 6624d707b9fSOleg Nesterov { 66323657bb1STejun Heo /* 66423657bb1STejun Heo * The following wmb is paired with the implied mb in 66523657bb1STejun Heo * test_and_set_bit(PENDING) and ensures all updates to @work made 66623657bb1STejun Heo * here are visible to and precede any updates by the next PENDING 66723657bb1STejun Heo * owner. 66823657bb1STejun Heo */ 66923657bb1STejun Heo smp_wmb(); 6707c3eed5cSTejun Heo set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); 671346c09f8SRoman Pen /* 672346c09f8SRoman Pen * The following mb guarantees that previous clear of a PENDING bit 673346c09f8SRoman Pen * will not be reordered with any speculative LOADS or STORES from 674346c09f8SRoman Pen * work->current_func, which is executed afterwards. This possible 6758bdc6201SLiu Song * reordering can lead to a missed execution on attempt to queue 676346c09f8SRoman Pen * the same @work. E.g. consider this case: 677346c09f8SRoman Pen * 678346c09f8SRoman Pen * CPU#0 CPU#1 679346c09f8SRoman Pen * ---------------------------- -------------------------------- 680346c09f8SRoman Pen * 681346c09f8SRoman Pen * 1 STORE event_indicated 682346c09f8SRoman Pen * 2 queue_work_on() { 683346c09f8SRoman Pen * 3 test_and_set_bit(PENDING) 684346c09f8SRoman Pen * 4 } set_..._and_clear_pending() { 685346c09f8SRoman Pen * 5 set_work_data() # clear bit 686346c09f8SRoman Pen * 6 smp_mb() 687346c09f8SRoman Pen * 7 work->current_func() { 688346c09f8SRoman Pen * 8 LOAD event_indicated 689346c09f8SRoman Pen * } 690346c09f8SRoman Pen * 691346c09f8SRoman Pen * Without an explicit full barrier speculative LOAD on line 8 can 692346c09f8SRoman Pen * be executed before CPU#0 does STORE on line 1. If that happens, 693346c09f8SRoman Pen * CPU#0 observes the PENDING bit is still set and new execution of 694346c09f8SRoman Pen * a @work is not queued in a hope, that CPU#1 will eventually 695346c09f8SRoman Pen * finish the queued @work. Meanwhile CPU#1 does not see 696346c09f8SRoman Pen * event_indicated is set, because speculative LOAD was executed 697346c09f8SRoman Pen * before actual STORE. 698346c09f8SRoman Pen */ 699346c09f8SRoman Pen smp_mb(); 7004d707b9fSOleg Nesterov } 7014d707b9fSOleg Nesterov 7027a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 703365970a1SDavid Howells { 7047c3eed5cSTejun Heo smp_wmb(); /* see set_work_pool_and_clear_pending() */ 7057c3eed5cSTejun Heo set_work_data(work, WORK_STRUCT_NO_POOL, 0); 7067a22ad75STejun Heo } 7077a22ad75STejun Heo 708112202d9STejun Heo static struct pool_workqueue *get_work_pwq(struct work_struct *work) 7097a22ad75STejun Heo { 710e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 7117a22ad75STejun Heo 712112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 713e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 714e120153dSTejun Heo else 715e120153dSTejun Heo return NULL; 7167a22ad75STejun Heo } 7177a22ad75STejun Heo 7187c3eed5cSTejun Heo /** 7197c3eed5cSTejun Heo * get_work_pool - return the worker_pool a given work was associated with 7207c3eed5cSTejun Heo * @work: the work item of interest 7217c3eed5cSTejun Heo * 72268e13a67SLai Jiangshan * Pools are created and destroyed under wq_pool_mutex, and allows read 72324acfb71SThomas Gleixner * access under RCU read lock. As such, this function should be 72424acfb71SThomas Gleixner * called under wq_pool_mutex or inside of a rcu_read_lock() region. 725fa1b54e6STejun Heo * 726fa1b54e6STejun Heo * All fields of the returned pool are accessible as long as the above 727fa1b54e6STejun Heo * mentioned locking is in effect. If the returned pool needs to be used 728fa1b54e6STejun Heo * beyond the critical section, the caller is responsible for ensuring the 729fa1b54e6STejun Heo * returned pool is and stays online. 730d185af30SYacine Belkadi * 731d185af30SYacine Belkadi * Return: The worker_pool @work was last associated with. %NULL if none. 7327c3eed5cSTejun Heo */ 7337c3eed5cSTejun Heo static struct worker_pool *get_work_pool(struct work_struct *work) 7347a22ad75STejun Heo { 735e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 7367c3eed5cSTejun Heo int pool_id; 7377a22ad75STejun Heo 73868e13a67SLai Jiangshan assert_rcu_or_pool_mutex(); 739fa1b54e6STejun Heo 740112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 741112202d9STejun Heo return ((struct pool_workqueue *) 7427c3eed5cSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->pool; 7437a22ad75STejun Heo 7447c3eed5cSTejun Heo pool_id = data >> WORK_OFFQ_POOL_SHIFT; 7457c3eed5cSTejun Heo if (pool_id == WORK_OFFQ_POOL_NONE) 7467a22ad75STejun Heo return NULL; 7477a22ad75STejun Heo 748fa1b54e6STejun Heo return idr_find(&worker_pool_idr, pool_id); 7497c3eed5cSTejun Heo } 7507c3eed5cSTejun Heo 7517c3eed5cSTejun Heo /** 7527c3eed5cSTejun Heo * get_work_pool_id - return the worker pool ID a given work is associated with 7537c3eed5cSTejun Heo * @work: the work item of interest 7547c3eed5cSTejun Heo * 755d185af30SYacine Belkadi * Return: The worker_pool ID @work was last associated with. 7567c3eed5cSTejun Heo * %WORK_OFFQ_POOL_NONE if none. 7577c3eed5cSTejun Heo */ 7587c3eed5cSTejun Heo static int get_work_pool_id(struct work_struct *work) 7597c3eed5cSTejun Heo { 76054d5b7d0SLai Jiangshan unsigned long data = atomic_long_read(&work->data); 7617c3eed5cSTejun Heo 762112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 763112202d9STejun Heo return ((struct pool_workqueue *) 76454d5b7d0SLai Jiangshan (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; 76554d5b7d0SLai Jiangshan 76654d5b7d0SLai Jiangshan return data >> WORK_OFFQ_POOL_SHIFT; 7677c3eed5cSTejun Heo } 7687c3eed5cSTejun Heo 769bbb68dfaSTejun Heo static void mark_work_canceling(struct work_struct *work) 770bbb68dfaSTejun Heo { 7717c3eed5cSTejun Heo unsigned long pool_id = get_work_pool_id(work); 772bbb68dfaSTejun Heo 7737c3eed5cSTejun Heo pool_id <<= WORK_OFFQ_POOL_SHIFT; 7747c3eed5cSTejun Heo set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); 775bbb68dfaSTejun Heo } 776bbb68dfaSTejun Heo 777bbb68dfaSTejun Heo static bool work_is_canceling(struct work_struct *work) 778bbb68dfaSTejun Heo { 779bbb68dfaSTejun Heo unsigned long data = atomic_long_read(&work->data); 780bbb68dfaSTejun Heo 781112202d9STejun Heo return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); 782bbb68dfaSTejun Heo } 783bbb68dfaSTejun Heo 784e22bee78STejun Heo /* 7853270476aSTejun Heo * Policy functions. These define the policies on how the global worker 7863270476aSTejun Heo * pools are managed. Unless noted otherwise, these functions assume that 787d565ed63STejun Heo * they're being called with pool->lock held. 788e22bee78STejun Heo */ 789e22bee78STejun Heo 79063d95a91STejun Heo static bool __need_more_worker(struct worker_pool *pool) 791649027d7STejun Heo { 792bc35f7efSLai Jiangshan return !pool->nr_running; 793649027d7STejun Heo } 794649027d7STejun Heo 795e22bee78STejun Heo /* 796e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 797e22bee78STejun Heo * running workers. 798974271c4STejun Heo * 799974271c4STejun Heo * Note that, because unbound workers never contribute to nr_running, this 800706026c2STejun Heo * function will always return %true for unbound pools as long as the 801974271c4STejun Heo * worklist isn't empty. 802e22bee78STejun Heo */ 80363d95a91STejun Heo static bool need_more_worker(struct worker_pool *pool) 804e22bee78STejun Heo { 80563d95a91STejun Heo return !list_empty(&pool->worklist) && __need_more_worker(pool); 806e22bee78STejun Heo } 807e22bee78STejun Heo 808e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 80963d95a91STejun Heo static bool may_start_working(struct worker_pool *pool) 810e22bee78STejun Heo { 81163d95a91STejun Heo return pool->nr_idle; 812e22bee78STejun Heo } 813e22bee78STejun Heo 814e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 81563d95a91STejun Heo static bool keep_working(struct worker_pool *pool) 816e22bee78STejun Heo { 817bc35f7efSLai Jiangshan return !list_empty(&pool->worklist) && (pool->nr_running <= 1); 818e22bee78STejun Heo } 819e22bee78STejun Heo 820e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 82163d95a91STejun Heo static bool need_to_create_worker(struct worker_pool *pool) 822e22bee78STejun Heo { 82363d95a91STejun Heo return need_more_worker(pool) && !may_start_working(pool); 824e22bee78STejun Heo } 825e22bee78STejun Heo 826e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 82763d95a91STejun Heo static bool too_many_workers(struct worker_pool *pool) 828e22bee78STejun Heo { 829692b4825STejun Heo bool managing = pool->flags & POOL_MANAGER_ACTIVE; 83063d95a91STejun Heo int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 83163d95a91STejun Heo int nr_busy = pool->nr_workers - nr_idle; 832e22bee78STejun Heo 833e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 834e22bee78STejun Heo } 835e22bee78STejun Heo 836e22bee78STejun Heo /* 837e22bee78STejun Heo * Wake up functions. 838e22bee78STejun Heo */ 839e22bee78STejun Heo 8402c1f1a91SLai Jiangshan /* Return the first idle worker. Called with pool->lock held. */ 8411037de36SLai Jiangshan static struct worker *first_idle_worker(struct worker_pool *pool) 8427e11629dSTejun Heo { 84363d95a91STejun Heo if (unlikely(list_empty(&pool->idle_list))) 8447e11629dSTejun Heo return NULL; 8457e11629dSTejun Heo 84663d95a91STejun Heo return list_first_entry(&pool->idle_list, struct worker, entry); 8477e11629dSTejun Heo } 8487e11629dSTejun Heo 8497e11629dSTejun Heo /** 8507e11629dSTejun Heo * wake_up_worker - wake up an idle worker 85163d95a91STejun Heo * @pool: worker pool to wake worker from 8527e11629dSTejun Heo * 85363d95a91STejun Heo * Wake up the first idle worker of @pool. 8547e11629dSTejun Heo * 8557e11629dSTejun Heo * CONTEXT: 856a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 8577e11629dSTejun Heo */ 85863d95a91STejun Heo static void wake_up_worker(struct worker_pool *pool) 8597e11629dSTejun Heo { 8601037de36SLai Jiangshan struct worker *worker = first_idle_worker(pool); 8617e11629dSTejun Heo 8627e11629dSTejun Heo if (likely(worker)) 8637e11629dSTejun Heo wake_up_process(worker->task); 8647e11629dSTejun Heo } 8657e11629dSTejun Heo 8664690c4abSTejun Heo /** 8676d25be57SThomas Gleixner * wq_worker_running - a worker is running again 868e22bee78STejun Heo * @task: task waking up 869e22bee78STejun Heo * 8706d25be57SThomas Gleixner * This function is called when a worker returns from schedule() 871e22bee78STejun Heo */ 8726d25be57SThomas Gleixner void wq_worker_running(struct task_struct *task) 873e22bee78STejun Heo { 874e22bee78STejun Heo struct worker *worker = kthread_data(task); 875e22bee78STejun Heo 8766d25be57SThomas Gleixner if (!worker->sleeping) 8776d25be57SThomas Gleixner return; 87807edfeceSFrederic Weisbecker 87907edfeceSFrederic Weisbecker /* 88007edfeceSFrederic Weisbecker * If preempted by unbind_workers() between the WORKER_NOT_RUNNING check 88107edfeceSFrederic Weisbecker * and the nr_running increment below, we may ruin the nr_running reset 88207edfeceSFrederic Weisbecker * and leave with an unexpected pool->nr_running == 1 on the newly unbound 88307edfeceSFrederic Weisbecker * pool. Protect against such race. 88407edfeceSFrederic Weisbecker */ 88507edfeceSFrederic Weisbecker preempt_disable(); 8866d25be57SThomas Gleixner if (!(worker->flags & WORKER_NOT_RUNNING)) 887bc35f7efSLai Jiangshan worker->pool->nr_running++; 88807edfeceSFrederic Weisbecker preempt_enable(); 8896d25be57SThomas Gleixner worker->sleeping = 0; 89036576000SJoonsoo Kim } 891e22bee78STejun Heo 892e22bee78STejun Heo /** 893e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 894e22bee78STejun Heo * @task: task going to sleep 895e22bee78STejun Heo * 8966d25be57SThomas Gleixner * This function is called from schedule() when a busy worker is 897ccf45156SLai Jiangshan * going to sleep. 898e22bee78STejun Heo */ 8996d25be57SThomas Gleixner void wq_worker_sleeping(struct task_struct *task) 900e22bee78STejun Heo { 901cc5bff38SLai Jiangshan struct worker *worker = kthread_data(task); 902111c225aSTejun Heo struct worker_pool *pool; 903e22bee78STejun Heo 904111c225aSTejun Heo /* 905111c225aSTejun Heo * Rescuers, which may not have all the fields set up like normal 906111c225aSTejun Heo * workers, also reach here, let's not access anything before 907111c225aSTejun Heo * checking NOT_RUNNING. 908111c225aSTejun Heo */ 9092d64672eSSteven Rostedt if (worker->flags & WORKER_NOT_RUNNING) 9106d25be57SThomas Gleixner return; 911e22bee78STejun Heo 912111c225aSTejun Heo pool = worker->pool; 913111c225aSTejun Heo 91462849a96SSebastian Andrzej Siewior /* Return if preempted before wq_worker_running() was reached */ 91562849a96SSebastian Andrzej Siewior if (worker->sleeping) 9166d25be57SThomas Gleixner return; 9176d25be57SThomas Gleixner 9186d25be57SThomas Gleixner worker->sleeping = 1; 919a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 920e22bee78STejun Heo 921e22bee78STejun Heo /* 92245c753f5SFrederic Weisbecker * Recheck in case unbind_workers() preempted us. We don't 92345c753f5SFrederic Weisbecker * want to decrement nr_running after the worker is unbound 92445c753f5SFrederic Weisbecker * and nr_running has been reset. 92545c753f5SFrederic Weisbecker */ 92645c753f5SFrederic Weisbecker if (worker->flags & WORKER_NOT_RUNNING) { 92745c753f5SFrederic Weisbecker raw_spin_unlock_irq(&pool->lock); 92845c753f5SFrederic Weisbecker return; 92945c753f5SFrederic Weisbecker } 93045c753f5SFrederic Weisbecker 931bc35f7efSLai Jiangshan pool->nr_running--; 932bc35f7efSLai Jiangshan if (need_more_worker(pool)) 933cc5bff38SLai Jiangshan wake_up_worker(pool); 934a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 935e22bee78STejun Heo } 936e22bee78STejun Heo 937e22bee78STejun Heo /** 9381b69ac6bSJohannes Weiner * wq_worker_last_func - retrieve worker's last work function 9398194fe94SBart Van Assche * @task: Task to retrieve last work function of. 9401b69ac6bSJohannes Weiner * 9411b69ac6bSJohannes Weiner * Determine the last function a worker executed. This is called from 9421b69ac6bSJohannes Weiner * the scheduler to get a worker's last known identity. 9431b69ac6bSJohannes Weiner * 9441b69ac6bSJohannes Weiner * CONTEXT: 945a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(rq->lock) 9461b69ac6bSJohannes Weiner * 9474b047002SJohannes Weiner * This function is called during schedule() when a kworker is going 9484b047002SJohannes Weiner * to sleep. It's used by psi to identify aggregation workers during 9494b047002SJohannes Weiner * dequeuing, to allow periodic aggregation to shut-off when that 9504b047002SJohannes Weiner * worker is the last task in the system or cgroup to go to sleep. 9514b047002SJohannes Weiner * 9524b047002SJohannes Weiner * As this function doesn't involve any workqueue-related locking, it 9534b047002SJohannes Weiner * only returns stable values when called from inside the scheduler's 9544b047002SJohannes Weiner * queuing and dequeuing paths, when @task, which must be a kworker, 9554b047002SJohannes Weiner * is guaranteed to not be processing any works. 9564b047002SJohannes Weiner * 9571b69ac6bSJohannes Weiner * Return: 9581b69ac6bSJohannes Weiner * The last work function %current executed as a worker, NULL if it 9591b69ac6bSJohannes Weiner * hasn't executed any work yet. 9601b69ac6bSJohannes Weiner */ 9611b69ac6bSJohannes Weiner work_func_t wq_worker_last_func(struct task_struct *task) 9621b69ac6bSJohannes Weiner { 9631b69ac6bSJohannes Weiner struct worker *worker = kthread_data(task); 9641b69ac6bSJohannes Weiner 9651b69ac6bSJohannes Weiner return worker->last_func; 9661b69ac6bSJohannes Weiner } 9671b69ac6bSJohannes Weiner 9681b69ac6bSJohannes Weiner /** 969e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 970cb444766STejun Heo * @worker: self 971d302f017STejun Heo * @flags: flags to set 972d302f017STejun Heo * 973228f1d00SLai Jiangshan * Set @flags in @worker->flags and adjust nr_running accordingly. 974d302f017STejun Heo * 975cb444766STejun Heo * CONTEXT: 976a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) 977d302f017STejun Heo */ 978228f1d00SLai Jiangshan static inline void worker_set_flags(struct worker *worker, unsigned int flags) 979d302f017STejun Heo { 980bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 981e22bee78STejun Heo 982cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 983cb444766STejun Heo 984228f1d00SLai Jiangshan /* If transitioning into NOT_RUNNING, adjust nr_running. */ 985e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 986e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 987bc35f7efSLai Jiangshan pool->nr_running--; 988e22bee78STejun Heo } 989e22bee78STejun Heo 990d302f017STejun Heo worker->flags |= flags; 991d302f017STejun Heo } 992d302f017STejun Heo 993d302f017STejun Heo /** 994e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 995cb444766STejun Heo * @worker: self 996d302f017STejun Heo * @flags: flags to clear 997d302f017STejun Heo * 998e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 999d302f017STejun Heo * 1000cb444766STejun Heo * CONTEXT: 1001a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) 1002d302f017STejun Heo */ 1003d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 1004d302f017STejun Heo { 100563d95a91STejun Heo struct worker_pool *pool = worker->pool; 1006e22bee78STejun Heo unsigned int oflags = worker->flags; 1007e22bee78STejun Heo 1008cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 1009cb444766STejun Heo 1010d302f017STejun Heo worker->flags &= ~flags; 1011e22bee78STejun Heo 101242c025f3STejun Heo /* 101342c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 101442c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 101542c025f3STejun Heo * of multiple flags, not a single flag. 101642c025f3STejun Heo */ 1017e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 1018e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 1019bc35f7efSLai Jiangshan pool->nr_running++; 1020d302f017STejun Heo } 1021d302f017STejun Heo 1022d302f017STejun Heo /** 10238cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 1024c9e7cf27STejun Heo * @pool: pool of interest 10258cca0eeaSTejun Heo * @work: work to find worker for 10268cca0eeaSTejun Heo * 1027c9e7cf27STejun Heo * Find a worker which is executing @work on @pool by searching 1028c9e7cf27STejun Heo * @pool->busy_hash which is keyed by the address of @work. For a worker 1029a2c1c57bSTejun Heo * to match, its current execution should match the address of @work and 1030a2c1c57bSTejun Heo * its work function. This is to avoid unwanted dependency between 1031a2c1c57bSTejun Heo * unrelated work executions through a work item being recycled while still 1032a2c1c57bSTejun Heo * being executed. 1033a2c1c57bSTejun Heo * 1034a2c1c57bSTejun Heo * This is a bit tricky. A work item may be freed once its execution 1035a2c1c57bSTejun Heo * starts and nothing prevents the freed area from being recycled for 1036a2c1c57bSTejun Heo * another work item. If the same work item address ends up being reused 1037a2c1c57bSTejun Heo * before the original execution finishes, workqueue will identify the 1038a2c1c57bSTejun Heo * recycled work item as currently executing and make it wait until the 1039a2c1c57bSTejun Heo * current execution finishes, introducing an unwanted dependency. 1040a2c1c57bSTejun Heo * 1041c5aa87bbSTejun Heo * This function checks the work item address and work function to avoid 1042c5aa87bbSTejun Heo * false positives. Note that this isn't complete as one may construct a 1043c5aa87bbSTejun Heo * work function which can introduce dependency onto itself through a 1044c5aa87bbSTejun Heo * recycled work item. Well, if somebody wants to shoot oneself in the 1045c5aa87bbSTejun Heo * foot that badly, there's only so much we can do, and if such deadlock 1046c5aa87bbSTejun Heo * actually occurs, it should be easy to locate the culprit work function. 10478cca0eeaSTejun Heo * 10488cca0eeaSTejun Heo * CONTEXT: 1049a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 10508cca0eeaSTejun Heo * 1051d185af30SYacine Belkadi * Return: 1052d185af30SYacine Belkadi * Pointer to worker which is executing @work if found, %NULL 10538cca0eeaSTejun Heo * otherwise. 10548cca0eeaSTejun Heo */ 1055c9e7cf27STejun Heo static struct worker *find_worker_executing_work(struct worker_pool *pool, 10568cca0eeaSTejun Heo struct work_struct *work) 10578cca0eeaSTejun Heo { 105842f8570fSSasha Levin struct worker *worker; 105942f8570fSSasha Levin 1060b67bfe0dSSasha Levin hash_for_each_possible(pool->busy_hash, worker, hentry, 1061a2c1c57bSTejun Heo (unsigned long)work) 1062a2c1c57bSTejun Heo if (worker->current_work == work && 1063a2c1c57bSTejun Heo worker->current_func == work->func) 106442f8570fSSasha Levin return worker; 106542f8570fSSasha Levin 106642f8570fSSasha Levin return NULL; 10678cca0eeaSTejun Heo } 10688cca0eeaSTejun Heo 10698cca0eeaSTejun Heo /** 1070bf4ede01STejun Heo * move_linked_works - move linked works to a list 1071bf4ede01STejun Heo * @work: start of series of works to be scheduled 1072bf4ede01STejun Heo * @head: target list to append @work to 1073402dd89dSShailendra Verma * @nextp: out parameter for nested worklist walking 1074bf4ede01STejun Heo * 1075bf4ede01STejun Heo * Schedule linked works starting from @work to @head. Work series to 1076bf4ede01STejun Heo * be scheduled starts at @work and includes any consecutive work with 1077bf4ede01STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 1078bf4ede01STejun Heo * 1079bf4ede01STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 1080bf4ede01STejun Heo * the last scheduled work. This allows move_linked_works() to be 1081bf4ede01STejun Heo * nested inside outer list_for_each_entry_safe(). 1082bf4ede01STejun Heo * 1083bf4ede01STejun Heo * CONTEXT: 1084a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 1085bf4ede01STejun Heo */ 1086bf4ede01STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1087bf4ede01STejun Heo struct work_struct **nextp) 1088bf4ede01STejun Heo { 1089bf4ede01STejun Heo struct work_struct *n; 1090bf4ede01STejun Heo 1091bf4ede01STejun Heo /* 1092bf4ede01STejun Heo * Linked worklist will always end before the end of the list, 1093bf4ede01STejun Heo * use NULL for list head. 1094bf4ede01STejun Heo */ 1095bf4ede01STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1096bf4ede01STejun Heo list_move_tail(&work->entry, head); 1097bf4ede01STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1098bf4ede01STejun Heo break; 1099bf4ede01STejun Heo } 1100bf4ede01STejun Heo 1101bf4ede01STejun Heo /* 1102bf4ede01STejun Heo * If we're already inside safe list traversal and have moved 1103bf4ede01STejun Heo * multiple works to the scheduled queue, the next position 1104bf4ede01STejun Heo * needs to be updated. 1105bf4ede01STejun Heo */ 1106bf4ede01STejun Heo if (nextp) 1107bf4ede01STejun Heo *nextp = n; 1108bf4ede01STejun Heo } 1109bf4ede01STejun Heo 11108864b4e5STejun Heo /** 11118864b4e5STejun Heo * get_pwq - get an extra reference on the specified pool_workqueue 11128864b4e5STejun Heo * @pwq: pool_workqueue to get 11138864b4e5STejun Heo * 11148864b4e5STejun Heo * Obtain an extra reference on @pwq. The caller should guarantee that 11158864b4e5STejun Heo * @pwq has positive refcnt and be holding the matching pool->lock. 11168864b4e5STejun Heo */ 11178864b4e5STejun Heo static void get_pwq(struct pool_workqueue *pwq) 11188864b4e5STejun Heo { 11198864b4e5STejun Heo lockdep_assert_held(&pwq->pool->lock); 11208864b4e5STejun Heo WARN_ON_ONCE(pwq->refcnt <= 0); 11218864b4e5STejun Heo pwq->refcnt++; 11228864b4e5STejun Heo } 11238864b4e5STejun Heo 11248864b4e5STejun Heo /** 11258864b4e5STejun Heo * put_pwq - put a pool_workqueue reference 11268864b4e5STejun Heo * @pwq: pool_workqueue to put 11278864b4e5STejun Heo * 11288864b4e5STejun Heo * Drop a reference of @pwq. If its refcnt reaches zero, schedule its 11298864b4e5STejun Heo * destruction. The caller should be holding the matching pool->lock. 11308864b4e5STejun Heo */ 11318864b4e5STejun Heo static void put_pwq(struct pool_workqueue *pwq) 11328864b4e5STejun Heo { 11338864b4e5STejun Heo lockdep_assert_held(&pwq->pool->lock); 11348864b4e5STejun Heo if (likely(--pwq->refcnt)) 11358864b4e5STejun Heo return; 11368864b4e5STejun Heo if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) 11378864b4e5STejun Heo return; 11388864b4e5STejun Heo /* 11398864b4e5STejun Heo * @pwq can't be released under pool->lock, bounce to 11408864b4e5STejun Heo * pwq_unbound_release_workfn(). This never recurses on the same 11418864b4e5STejun Heo * pool->lock as this path is taken only for unbound workqueues and 11428864b4e5STejun Heo * the release work item is scheduled on a per-cpu workqueue. To 11438864b4e5STejun Heo * avoid lockdep warning, unbound pool->locks are given lockdep 11448864b4e5STejun Heo * subclass of 1 in get_unbound_pool(). 11458864b4e5STejun Heo */ 11468864b4e5STejun Heo schedule_work(&pwq->unbound_release_work); 11478864b4e5STejun Heo } 11488864b4e5STejun Heo 1149dce90d47STejun Heo /** 1150dce90d47STejun Heo * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock 1151dce90d47STejun Heo * @pwq: pool_workqueue to put (can be %NULL) 1152dce90d47STejun Heo * 1153dce90d47STejun Heo * put_pwq() with locking. This function also allows %NULL @pwq. 1154dce90d47STejun Heo */ 1155dce90d47STejun Heo static void put_pwq_unlocked(struct pool_workqueue *pwq) 1156dce90d47STejun Heo { 1157dce90d47STejun Heo if (pwq) { 1158dce90d47STejun Heo /* 115924acfb71SThomas Gleixner * As both pwqs and pools are RCU protected, the 1160dce90d47STejun Heo * following lock operations are safe. 1161dce90d47STejun Heo */ 1162a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pwq->pool->lock); 1163dce90d47STejun Heo put_pwq(pwq); 1164a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pwq->pool->lock); 1165dce90d47STejun Heo } 1166dce90d47STejun Heo } 1167dce90d47STejun Heo 1168f97a4a1aSLai Jiangshan static void pwq_activate_inactive_work(struct work_struct *work) 1169bf4ede01STejun Heo { 1170112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 1171bf4ede01STejun Heo 1172bf4ede01STejun Heo trace_workqueue_activate_work(work); 117382607adcSTejun Heo if (list_empty(&pwq->pool->worklist)) 117482607adcSTejun Heo pwq->pool->watchdog_ts = jiffies; 1175112202d9STejun Heo move_linked_works(work, &pwq->pool->worklist, NULL); 1176f97a4a1aSLai Jiangshan __clear_bit(WORK_STRUCT_INACTIVE_BIT, work_data_bits(work)); 1177112202d9STejun Heo pwq->nr_active++; 1178bf4ede01STejun Heo } 1179bf4ede01STejun Heo 1180f97a4a1aSLai Jiangshan static void pwq_activate_first_inactive(struct pool_workqueue *pwq) 11813aa62497SLai Jiangshan { 1182f97a4a1aSLai Jiangshan struct work_struct *work = list_first_entry(&pwq->inactive_works, 11833aa62497SLai Jiangshan struct work_struct, entry); 11843aa62497SLai Jiangshan 1185f97a4a1aSLai Jiangshan pwq_activate_inactive_work(work); 11863aa62497SLai Jiangshan } 11873aa62497SLai Jiangshan 1188bf4ede01STejun Heo /** 1189112202d9STejun Heo * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight 1190112202d9STejun Heo * @pwq: pwq of interest 1191c4560c2cSLai Jiangshan * @work_data: work_data of work which left the queue 1192bf4ede01STejun Heo * 1193bf4ede01STejun Heo * A work either has completed or is removed from pending queue, 1194112202d9STejun Heo * decrement nr_in_flight of its pwq and handle workqueue flushing. 1195bf4ede01STejun Heo * 1196bf4ede01STejun Heo * CONTEXT: 1197a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 1198bf4ede01STejun Heo */ 1199c4560c2cSLai Jiangshan static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data) 1200bf4ede01STejun Heo { 1201c4560c2cSLai Jiangshan int color = get_work_color(work_data); 1202c4560c2cSLai Jiangshan 1203018f3a13SLai Jiangshan if (!(work_data & WORK_STRUCT_INACTIVE)) { 1204112202d9STejun Heo pwq->nr_active--; 1205f97a4a1aSLai Jiangshan if (!list_empty(&pwq->inactive_works)) { 1206f97a4a1aSLai Jiangshan /* one down, submit an inactive one */ 1207112202d9STejun Heo if (pwq->nr_active < pwq->max_active) 1208f97a4a1aSLai Jiangshan pwq_activate_first_inactive(pwq); 1209bf4ede01STejun Heo } 1210018f3a13SLai Jiangshan } 1211018f3a13SLai Jiangshan 1212018f3a13SLai Jiangshan pwq->nr_in_flight[color]--; 1213bf4ede01STejun Heo 1214bf4ede01STejun Heo /* is flush in progress and are we at the flushing tip? */ 1215112202d9STejun Heo if (likely(pwq->flush_color != color)) 12168864b4e5STejun Heo goto out_put; 1217bf4ede01STejun Heo 1218bf4ede01STejun Heo /* are there still in-flight works? */ 1219112202d9STejun Heo if (pwq->nr_in_flight[color]) 12208864b4e5STejun Heo goto out_put; 1221bf4ede01STejun Heo 1222112202d9STejun Heo /* this pwq is done, clear flush_color */ 1223112202d9STejun Heo pwq->flush_color = -1; 1224bf4ede01STejun Heo 1225bf4ede01STejun Heo /* 1226112202d9STejun Heo * If this was the last pwq, wake up the first flusher. It 1227bf4ede01STejun Heo * will handle the rest. 1228bf4ede01STejun Heo */ 1229112202d9STejun Heo if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) 1230112202d9STejun Heo complete(&pwq->wq->first_flusher->done); 12318864b4e5STejun Heo out_put: 12328864b4e5STejun Heo put_pwq(pwq); 1233bf4ede01STejun Heo } 1234bf4ede01STejun Heo 123536e227d2STejun Heo /** 1236bbb68dfaSTejun Heo * try_to_grab_pending - steal work item from worklist and disable irq 123736e227d2STejun Heo * @work: work item to steal 123836e227d2STejun Heo * @is_dwork: @work is a delayed_work 1239bbb68dfaSTejun Heo * @flags: place to store irq state 124036e227d2STejun Heo * 124136e227d2STejun Heo * Try to grab PENDING bit of @work. This function can handle @work in any 1242d185af30SYacine Belkadi * stable state - idle, on timer or on worklist. 124336e227d2STejun Heo * 1244d185af30SYacine Belkadi * Return: 12453eb6b31bSMauro Carvalho Chehab * 12463eb6b31bSMauro Carvalho Chehab * ======== ================================================================ 124736e227d2STejun Heo * 1 if @work was pending and we successfully stole PENDING 124836e227d2STejun Heo * 0 if @work was idle and we claimed PENDING 124936e227d2STejun Heo * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 1250bbb68dfaSTejun Heo * -ENOENT if someone else is canceling @work, this state may persist 1251bbb68dfaSTejun Heo * for arbitrarily long 12523eb6b31bSMauro Carvalho Chehab * ======== ================================================================ 125336e227d2STejun Heo * 1254d185af30SYacine Belkadi * Note: 1255bbb68dfaSTejun Heo * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 1256e0aecdd8STejun Heo * interrupted while holding PENDING and @work off queue, irq must be 1257e0aecdd8STejun Heo * disabled on entry. This, combined with delayed_work->timer being 1258e0aecdd8STejun Heo * irqsafe, ensures that we return -EAGAIN for finite short period of time. 1259bbb68dfaSTejun Heo * 1260bbb68dfaSTejun Heo * On successful return, >= 0, irq is disabled and the caller is 1261bbb68dfaSTejun Heo * responsible for releasing it using local_irq_restore(*@flags). 1262bbb68dfaSTejun Heo * 1263e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 1264bf4ede01STejun Heo */ 1265bbb68dfaSTejun Heo static int try_to_grab_pending(struct work_struct *work, bool is_dwork, 1266bbb68dfaSTejun Heo unsigned long *flags) 1267bf4ede01STejun Heo { 1268d565ed63STejun Heo struct worker_pool *pool; 1269112202d9STejun Heo struct pool_workqueue *pwq; 1270bf4ede01STejun Heo 1271bbb68dfaSTejun Heo local_irq_save(*flags); 1272bbb68dfaSTejun Heo 127336e227d2STejun Heo /* try to steal the timer if it exists */ 127436e227d2STejun Heo if (is_dwork) { 127536e227d2STejun Heo struct delayed_work *dwork = to_delayed_work(work); 127636e227d2STejun Heo 1277e0aecdd8STejun Heo /* 1278e0aecdd8STejun Heo * dwork->timer is irqsafe. If del_timer() fails, it's 1279e0aecdd8STejun Heo * guaranteed that the timer is not queued anywhere and not 1280e0aecdd8STejun Heo * running on the local CPU. 1281e0aecdd8STejun Heo */ 128236e227d2STejun Heo if (likely(del_timer(&dwork->timer))) 128336e227d2STejun Heo return 1; 128436e227d2STejun Heo } 128536e227d2STejun Heo 128636e227d2STejun Heo /* try to claim PENDING the normal way */ 1287bf4ede01STejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 1288bf4ede01STejun Heo return 0; 1289bf4ede01STejun Heo 129024acfb71SThomas Gleixner rcu_read_lock(); 1291bf4ede01STejun Heo /* 1292bf4ede01STejun Heo * The queueing is in progress, or it is already queued. Try to 1293bf4ede01STejun Heo * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 1294bf4ede01STejun Heo */ 1295d565ed63STejun Heo pool = get_work_pool(work); 1296d565ed63STejun Heo if (!pool) 1297bbb68dfaSTejun Heo goto fail; 1298bf4ede01STejun Heo 1299a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&pool->lock); 1300bf4ede01STejun Heo /* 1301112202d9STejun Heo * work->data is guaranteed to point to pwq only while the work 1302112202d9STejun Heo * item is queued on pwq->wq, and both updating work->data to point 1303112202d9STejun Heo * to pwq on queueing and to pool on dequeueing are done under 1304112202d9STejun Heo * pwq->pool->lock. This in turn guarantees that, if work->data 1305112202d9STejun Heo * points to pwq which is associated with a locked pool, the work 13060b3dae68SLai Jiangshan * item is currently queued on that pool. 1307bf4ede01STejun Heo */ 1308112202d9STejun Heo pwq = get_work_pwq(work); 1309112202d9STejun Heo if (pwq && pwq->pool == pool) { 1310bf4ede01STejun Heo debug_work_deactivate(work); 13113aa62497SLai Jiangshan 13123aa62497SLai Jiangshan /* 1313018f3a13SLai Jiangshan * A cancelable inactive work item must be in the 1314018f3a13SLai Jiangshan * pwq->inactive_works since a queued barrier can't be 1315018f3a13SLai Jiangshan * canceled (see the comments in insert_wq_barrier()). 1316018f3a13SLai Jiangshan * 1317f97a4a1aSLai Jiangshan * An inactive work item cannot be grabbed directly because 1318d812796eSLai Jiangshan * it might have linked barrier work items which, if left 1319f97a4a1aSLai Jiangshan * on the inactive_works list, will confuse pwq->nr_active 132016062836STejun Heo * management later on and cause stall. Make sure the work 132116062836STejun Heo * item is activated before grabbing. 13223aa62497SLai Jiangshan */ 1323f97a4a1aSLai Jiangshan if (*work_data_bits(work) & WORK_STRUCT_INACTIVE) 1324f97a4a1aSLai Jiangshan pwq_activate_inactive_work(work); 13253aa62497SLai Jiangshan 1326bf4ede01STejun Heo list_del_init(&work->entry); 1327c4560c2cSLai Jiangshan pwq_dec_nr_in_flight(pwq, *work_data_bits(work)); 132836e227d2STejun Heo 1329112202d9STejun Heo /* work->data points to pwq iff queued, point to pool */ 13304468a00fSLai Jiangshan set_work_pool_and_keep_pending(work, pool->id); 13314468a00fSLai Jiangshan 1332a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&pool->lock); 133324acfb71SThomas Gleixner rcu_read_unlock(); 133436e227d2STejun Heo return 1; 1335bf4ede01STejun Heo } 1336a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&pool->lock); 1337bbb68dfaSTejun Heo fail: 133824acfb71SThomas Gleixner rcu_read_unlock(); 1339bbb68dfaSTejun Heo local_irq_restore(*flags); 1340bbb68dfaSTejun Heo if (work_is_canceling(work)) 1341bbb68dfaSTejun Heo return -ENOENT; 1342bbb68dfaSTejun Heo cpu_relax(); 134336e227d2STejun Heo return -EAGAIN; 1344bf4ede01STejun Heo } 1345bf4ede01STejun Heo 1346bf4ede01STejun Heo /** 1347706026c2STejun Heo * insert_work - insert a work into a pool 1348112202d9STejun Heo * @pwq: pwq @work belongs to 13494690c4abSTejun Heo * @work: work to insert 13504690c4abSTejun Heo * @head: insertion point 13514690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 13524690c4abSTejun Heo * 1353112202d9STejun Heo * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to 1354706026c2STejun Heo * work_struct flags. 13554690c4abSTejun Heo * 13564690c4abSTejun Heo * CONTEXT: 1357a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 1358365970a1SDavid Howells */ 1359112202d9STejun Heo static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, 1360112202d9STejun Heo struct list_head *head, unsigned int extra_flags) 1361b89deed3SOleg Nesterov { 1362112202d9STejun Heo struct worker_pool *pool = pwq->pool; 1363e1d8aa9fSFrederic Weisbecker 1364e89a85d6SWalter Wu /* record the work call stack in order to print it in KASAN reports */ 1365f70da745SMarco Elver kasan_record_aux_stack_noalloc(work); 1366e89a85d6SWalter Wu 13674690c4abSTejun Heo /* we own @work, set data and link */ 1368112202d9STejun Heo set_work_pwq(work, pwq, extra_flags); 13691a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 13708864b4e5STejun Heo get_pwq(pwq); 1371e22bee78STejun Heo 137263d95a91STejun Heo if (__need_more_worker(pool)) 137363d95a91STejun Heo wake_up_worker(pool); 1374b89deed3SOleg Nesterov } 1375b89deed3SOleg Nesterov 1376c8efcc25STejun Heo /* 1377c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 13788d03ecfeSTejun Heo * same workqueue. 1379c8efcc25STejun Heo */ 1380c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 1381c8efcc25STejun Heo { 1382c8efcc25STejun Heo struct worker *worker; 1383c8efcc25STejun Heo 13848d03ecfeSTejun Heo worker = current_wq_worker(); 1385c8efcc25STejun Heo /* 1386bf393fd4SBart Van Assche * Return %true iff I'm a worker executing a work item on @wq. If 13878d03ecfeSTejun Heo * I'm @worker, it's safe to dereference it without locking. 1388c8efcc25STejun Heo */ 1389112202d9STejun Heo return worker && worker->current_pwq->wq == wq; 1390c8efcc25STejun Heo } 1391c8efcc25STejun Heo 1392ef557180SMike Galbraith /* 1393ef557180SMike Galbraith * When queueing an unbound work item to a wq, prefer local CPU if allowed 1394ef557180SMike Galbraith * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to 1395ef557180SMike Galbraith * avoid perturbing sensitive tasks. 1396ef557180SMike Galbraith */ 1397ef557180SMike Galbraith static int wq_select_unbound_cpu(int cpu) 1398ef557180SMike Galbraith { 1399ef557180SMike Galbraith int new_cpu; 1400ef557180SMike Galbraith 1401f303fccbSTejun Heo if (likely(!wq_debug_force_rr_cpu)) { 1402ef557180SMike Galbraith if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) 1403ef557180SMike Galbraith return cpu; 1404a8ec5880SAmmar Faizi } else { 1405a8ec5880SAmmar Faizi pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n"); 1406f303fccbSTejun Heo } 1407f303fccbSTejun Heo 1408ef557180SMike Galbraith if (cpumask_empty(wq_unbound_cpumask)) 1409ef557180SMike Galbraith return cpu; 1410ef557180SMike Galbraith 1411ef557180SMike Galbraith new_cpu = __this_cpu_read(wq_rr_cpu_last); 1412ef557180SMike Galbraith new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask); 1413ef557180SMike Galbraith if (unlikely(new_cpu >= nr_cpu_ids)) { 1414ef557180SMike Galbraith new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask); 1415ef557180SMike Galbraith if (unlikely(new_cpu >= nr_cpu_ids)) 1416ef557180SMike Galbraith return cpu; 1417ef557180SMike Galbraith } 1418ef557180SMike Galbraith __this_cpu_write(wq_rr_cpu_last, new_cpu); 1419ef557180SMike Galbraith 1420ef557180SMike Galbraith return new_cpu; 1421ef557180SMike Galbraith } 1422ef557180SMike Galbraith 1423d84ff051STejun Heo static void __queue_work(int cpu, struct workqueue_struct *wq, 14241da177e4SLinus Torvalds struct work_struct *work) 14251da177e4SLinus Torvalds { 1426112202d9STejun Heo struct pool_workqueue *pwq; 1427c9178087STejun Heo struct worker_pool *last_pool; 14281e19ffc6STejun Heo struct list_head *worklist; 14298a2e8e5dSTejun Heo unsigned int work_flags; 1430b75cac93SJoonsoo Kim unsigned int req_cpu = cpu; 14318930cabaSTejun Heo 14328930cabaSTejun Heo /* 14338930cabaSTejun Heo * While a work item is PENDING && off queue, a task trying to 14348930cabaSTejun Heo * steal the PENDING will busy-loop waiting for it to either get 14358930cabaSTejun Heo * queued or lose PENDING. Grabbing PENDING and queueing should 14368930cabaSTejun Heo * happen with IRQ disabled. 14378930cabaSTejun Heo */ 14388e8eb730SFrederic Weisbecker lockdep_assert_irqs_disabled(); 14391da177e4SLinus Torvalds 14401e19ffc6STejun Heo 144133e3f0a3SRichard Clark /* 144233e3f0a3SRichard Clark * For a draining wq, only works from the same workqueue are 144333e3f0a3SRichard Clark * allowed. The __WQ_DESTROYING helps to spot the issue that 144433e3f0a3SRichard Clark * queues a new work item to a wq after destroy_workqueue(wq). 144533e3f0a3SRichard Clark */ 144633e3f0a3SRichard Clark if (unlikely(wq->flags & (__WQ_DESTROYING | __WQ_DRAINING) && 144733e3f0a3SRichard Clark WARN_ON_ONCE(!is_chained_work(wq)))) 1448e41e704bSTejun Heo return; 144924acfb71SThomas Gleixner rcu_read_lock(); 14509e8cd2f5STejun Heo retry: 1451aa202f1fSHillf Danton /* pwq which will be used unless @work is executing elsewhere */ 1452aa202f1fSHillf Danton if (wq->flags & WQ_UNBOUND) { 1453df2d5ae4STejun Heo if (req_cpu == WORK_CPU_UNBOUND) 1454ef557180SMike Galbraith cpu = wq_select_unbound_cpu(raw_smp_processor_id()); 1455df2d5ae4STejun Heo pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); 1456aa202f1fSHillf Danton } else { 1457aa202f1fSHillf Danton if (req_cpu == WORK_CPU_UNBOUND) 1458aa202f1fSHillf Danton cpu = raw_smp_processor_id(); 1459aa202f1fSHillf Danton pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); 1460aa202f1fSHillf Danton } 1461f3421797STejun Heo 146218aa9effSTejun Heo /* 1463c9178087STejun Heo * If @work was previously on a different pool, it might still be 1464c9178087STejun Heo * running there, in which case the work needs to be queued on that 1465c9178087STejun Heo * pool to guarantee non-reentrancy. 146618aa9effSTejun Heo */ 1467c9e7cf27STejun Heo last_pool = get_work_pool(work); 1468112202d9STejun Heo if (last_pool && last_pool != pwq->pool) { 146918aa9effSTejun Heo struct worker *worker; 147018aa9effSTejun Heo 1471a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&last_pool->lock); 147218aa9effSTejun Heo 1473c9e7cf27STejun Heo worker = find_worker_executing_work(last_pool, work); 147418aa9effSTejun Heo 1475112202d9STejun Heo if (worker && worker->current_pwq->wq == wq) { 1476c9178087STejun Heo pwq = worker->current_pwq; 14778594fadeSLai Jiangshan } else { 147818aa9effSTejun Heo /* meh... not running there, queue here */ 1479a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&last_pool->lock); 1480a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&pwq->pool->lock); 148118aa9effSTejun Heo } 14828930cabaSTejun Heo } else { 1483a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&pwq->pool->lock); 14848930cabaSTejun Heo } 1485502ca9d8STejun Heo 14869e8cd2f5STejun Heo /* 14879e8cd2f5STejun Heo * pwq is determined and locked. For unbound pools, we could have 14889e8cd2f5STejun Heo * raced with pwq release and it could already be dead. If its 14899e8cd2f5STejun Heo * refcnt is zero, repeat pwq selection. Note that pwqs never die 1490df2d5ae4STejun Heo * without another pwq replacing it in the numa_pwq_tbl or while 1491df2d5ae4STejun Heo * work items are executing on it, so the retrying is guaranteed to 14929e8cd2f5STejun Heo * make forward-progress. 14939e8cd2f5STejun Heo */ 14949e8cd2f5STejun Heo if (unlikely(!pwq->refcnt)) { 14959e8cd2f5STejun Heo if (wq->flags & WQ_UNBOUND) { 1496a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&pwq->pool->lock); 14979e8cd2f5STejun Heo cpu_relax(); 14989e8cd2f5STejun Heo goto retry; 14999e8cd2f5STejun Heo } 15009e8cd2f5STejun Heo /* oops */ 15019e8cd2f5STejun Heo WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", 15029e8cd2f5STejun Heo wq->name, cpu); 15039e8cd2f5STejun Heo } 15049e8cd2f5STejun Heo 1505112202d9STejun Heo /* pwq determined, queue */ 1506112202d9STejun Heo trace_workqueue_queue_work(req_cpu, pwq, work); 1507502ca9d8STejun Heo 150824acfb71SThomas Gleixner if (WARN_ON(!list_empty(&work->entry))) 150924acfb71SThomas Gleixner goto out; 15101e19ffc6STejun Heo 1511112202d9STejun Heo pwq->nr_in_flight[pwq->work_color]++; 1512112202d9STejun Heo work_flags = work_color_to_flags(pwq->work_color); 15131e19ffc6STejun Heo 1514112202d9STejun Heo if (likely(pwq->nr_active < pwq->max_active)) { 1515cdadf009STejun Heo trace_workqueue_activate_work(work); 1516112202d9STejun Heo pwq->nr_active++; 1517112202d9STejun Heo worklist = &pwq->pool->worklist; 151882607adcSTejun Heo if (list_empty(worklist)) 151982607adcSTejun Heo pwq->pool->watchdog_ts = jiffies; 15208a2e8e5dSTejun Heo } else { 1521f97a4a1aSLai Jiangshan work_flags |= WORK_STRUCT_INACTIVE; 1522f97a4a1aSLai Jiangshan worklist = &pwq->inactive_works; 15238a2e8e5dSTejun Heo } 15241e19ffc6STejun Heo 15250687c66bSZqiang debug_work_activate(work); 1526112202d9STejun Heo insert_work(pwq, work, worklist, work_flags); 15271e19ffc6STejun Heo 152824acfb71SThomas Gleixner out: 1529a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&pwq->pool->lock); 153024acfb71SThomas Gleixner rcu_read_unlock(); 15311da177e4SLinus Torvalds } 15321da177e4SLinus Torvalds 15330fcb78c2SRolf Eike Beer /** 1534c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1535c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1536c1a220e7SZhang Rui * @wq: workqueue to use 1537c1a220e7SZhang Rui * @work: work to queue 1538c1a220e7SZhang Rui * 1539c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1540443378f0SPaul E. McKenney * can't go away. Callers that fail to ensure that the specified 1541443378f0SPaul E. McKenney * CPU cannot go away will execute on a randomly chosen CPU. 1542*854f5cc5SPaul E. McKenney * But note well that callers specifying a CPU that never has been 1543*854f5cc5SPaul E. McKenney * online will get a splat. 1544d185af30SYacine Belkadi * 1545d185af30SYacine Belkadi * Return: %false if @work was already on a queue, %true otherwise. 1546c1a220e7SZhang Rui */ 1547d4283e93STejun Heo bool queue_work_on(int cpu, struct workqueue_struct *wq, 1548d4283e93STejun Heo struct work_struct *work) 1549c1a220e7SZhang Rui { 1550d4283e93STejun Heo bool ret = false; 15518930cabaSTejun Heo unsigned long flags; 15528930cabaSTejun Heo 15538930cabaSTejun Heo local_irq_save(flags); 1554c1a220e7SZhang Rui 155522df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 15564690c4abSTejun Heo __queue_work(cpu, wq, work); 1557d4283e93STejun Heo ret = true; 1558c1a220e7SZhang Rui } 15598930cabaSTejun Heo 15608930cabaSTejun Heo local_irq_restore(flags); 1561c1a220e7SZhang Rui return ret; 1562c1a220e7SZhang Rui } 1563ad7b1f84SMarc Dionne EXPORT_SYMBOL(queue_work_on); 1564c1a220e7SZhang Rui 15658204e0c1SAlexander Duyck /** 15668204e0c1SAlexander Duyck * workqueue_select_cpu_near - Select a CPU based on NUMA node 15678204e0c1SAlexander Duyck * @node: NUMA node ID that we want to select a CPU from 15688204e0c1SAlexander Duyck * 15698204e0c1SAlexander Duyck * This function will attempt to find a "random" cpu available on a given 15708204e0c1SAlexander Duyck * node. If there are no CPUs available on the given node it will return 15718204e0c1SAlexander Duyck * WORK_CPU_UNBOUND indicating that we should just schedule to any 15728204e0c1SAlexander Duyck * available CPU if we need to schedule this work. 15738204e0c1SAlexander Duyck */ 15748204e0c1SAlexander Duyck static int workqueue_select_cpu_near(int node) 15758204e0c1SAlexander Duyck { 15768204e0c1SAlexander Duyck int cpu; 15778204e0c1SAlexander Duyck 15788204e0c1SAlexander Duyck /* No point in doing this if NUMA isn't enabled for workqueues */ 15798204e0c1SAlexander Duyck if (!wq_numa_enabled) 15808204e0c1SAlexander Duyck return WORK_CPU_UNBOUND; 15818204e0c1SAlexander Duyck 15828204e0c1SAlexander Duyck /* Delay binding to CPU if node is not valid or online */ 15838204e0c1SAlexander Duyck if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) 15848204e0c1SAlexander Duyck return WORK_CPU_UNBOUND; 15858204e0c1SAlexander Duyck 15868204e0c1SAlexander Duyck /* Use local node/cpu if we are already there */ 15878204e0c1SAlexander Duyck cpu = raw_smp_processor_id(); 15888204e0c1SAlexander Duyck if (node == cpu_to_node(cpu)) 15898204e0c1SAlexander Duyck return cpu; 15908204e0c1SAlexander Duyck 15918204e0c1SAlexander Duyck /* Use "random" otherwise know as "first" online CPU of node */ 15928204e0c1SAlexander Duyck cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); 15938204e0c1SAlexander Duyck 15948204e0c1SAlexander Duyck /* If CPU is valid return that, otherwise just defer */ 15958204e0c1SAlexander Duyck return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND; 15968204e0c1SAlexander Duyck } 15978204e0c1SAlexander Duyck 15988204e0c1SAlexander Duyck /** 15998204e0c1SAlexander Duyck * queue_work_node - queue work on a "random" cpu for a given NUMA node 16008204e0c1SAlexander Duyck * @node: NUMA node that we are targeting the work for 16018204e0c1SAlexander Duyck * @wq: workqueue to use 16028204e0c1SAlexander Duyck * @work: work to queue 16038204e0c1SAlexander Duyck * 16048204e0c1SAlexander Duyck * We queue the work to a "random" CPU within a given NUMA node. The basic 16058204e0c1SAlexander Duyck * idea here is to provide a way to somehow associate work with a given 16068204e0c1SAlexander Duyck * NUMA node. 16078204e0c1SAlexander Duyck * 16088204e0c1SAlexander Duyck * This function will only make a best effort attempt at getting this onto 16098204e0c1SAlexander Duyck * the right NUMA node. If no node is requested or the requested node is 16108204e0c1SAlexander Duyck * offline then we just fall back to standard queue_work behavior. 16118204e0c1SAlexander Duyck * 16128204e0c1SAlexander Duyck * Currently the "random" CPU ends up being the first available CPU in the 16138204e0c1SAlexander Duyck * intersection of cpu_online_mask and the cpumask of the node, unless we 16148204e0c1SAlexander Duyck * are running on the node. In that case we just use the current CPU. 16158204e0c1SAlexander Duyck * 16168204e0c1SAlexander Duyck * Return: %false if @work was already on a queue, %true otherwise. 16178204e0c1SAlexander Duyck */ 16188204e0c1SAlexander Duyck bool queue_work_node(int node, struct workqueue_struct *wq, 16198204e0c1SAlexander Duyck struct work_struct *work) 16208204e0c1SAlexander Duyck { 16218204e0c1SAlexander Duyck unsigned long flags; 16228204e0c1SAlexander Duyck bool ret = false; 16238204e0c1SAlexander Duyck 16248204e0c1SAlexander Duyck /* 16258204e0c1SAlexander Duyck * This current implementation is specific to unbound workqueues. 16268204e0c1SAlexander Duyck * Specifically we only return the first available CPU for a given 16278204e0c1SAlexander Duyck * node instead of cycling through individual CPUs within the node. 16288204e0c1SAlexander Duyck * 16298204e0c1SAlexander Duyck * If this is used with a per-cpu workqueue then the logic in 16308204e0c1SAlexander Duyck * workqueue_select_cpu_near would need to be updated to allow for 16318204e0c1SAlexander Duyck * some round robin type logic. 16328204e0c1SAlexander Duyck */ 16338204e0c1SAlexander Duyck WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)); 16348204e0c1SAlexander Duyck 16358204e0c1SAlexander Duyck local_irq_save(flags); 16368204e0c1SAlexander Duyck 16378204e0c1SAlexander Duyck if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 16388204e0c1SAlexander Duyck int cpu = workqueue_select_cpu_near(node); 16398204e0c1SAlexander Duyck 16408204e0c1SAlexander Duyck __queue_work(cpu, wq, work); 16418204e0c1SAlexander Duyck ret = true; 16428204e0c1SAlexander Duyck } 16438204e0c1SAlexander Duyck 16448204e0c1SAlexander Duyck local_irq_restore(flags); 16458204e0c1SAlexander Duyck return ret; 16468204e0c1SAlexander Duyck } 16478204e0c1SAlexander Duyck EXPORT_SYMBOL_GPL(queue_work_node); 16488204e0c1SAlexander Duyck 16498c20feb6SKees Cook void delayed_work_timer_fn(struct timer_list *t) 16501da177e4SLinus Torvalds { 16518c20feb6SKees Cook struct delayed_work *dwork = from_timer(dwork, t, timer); 16521da177e4SLinus Torvalds 1653e0aecdd8STejun Heo /* should have been called from irqsafe timer with irq already off */ 165460c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 16551da177e4SLinus Torvalds } 16561438ade5SKonstantin Khlebnikov EXPORT_SYMBOL(delayed_work_timer_fn); 16571da177e4SLinus Torvalds 16587beb2edfSTejun Heo static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 165952bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 16601da177e4SLinus Torvalds { 16617beb2edfSTejun Heo struct timer_list *timer = &dwork->timer; 16627beb2edfSTejun Heo struct work_struct *work = &dwork->work; 16631da177e4SLinus Torvalds 1664637fdbaeSTejun Heo WARN_ON_ONCE(!wq); 16654b243563SSami Tolvanen WARN_ON_ONCE(timer->function != delayed_work_timer_fn); 1666fc4b514fSTejun Heo WARN_ON_ONCE(timer_pending(timer)); 1667fc4b514fSTejun Heo WARN_ON_ONCE(!list_empty(&work->entry)); 16687beb2edfSTejun Heo 16698852aac2STejun Heo /* 16708852aac2STejun Heo * If @delay is 0, queue @dwork->work immediately. This is for 16718852aac2STejun Heo * both optimization and correctness. The earliest @timer can 16728852aac2STejun Heo * expire is on the closest next tick and delayed_work users depend 16738852aac2STejun Heo * on that there's no such delay when @delay is 0. 16748852aac2STejun Heo */ 16758852aac2STejun Heo if (!delay) { 16768852aac2STejun Heo __queue_work(cpu, wq, &dwork->work); 16778852aac2STejun Heo return; 16788852aac2STejun Heo } 16798852aac2STejun Heo 168060c057bcSLai Jiangshan dwork->wq = wq; 16811265057fSTejun Heo dwork->cpu = cpu; 16827beb2edfSTejun Heo timer->expires = jiffies + delay; 16837beb2edfSTejun Heo 1684041bd12eSTejun Heo if (unlikely(cpu != WORK_CPU_UNBOUND)) 16857beb2edfSTejun Heo add_timer_on(timer, cpu); 1686041bd12eSTejun Heo else 1687041bd12eSTejun Heo add_timer(timer); 16887beb2edfSTejun Heo } 16891da177e4SLinus Torvalds 16900fcb78c2SRolf Eike Beer /** 16910fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 16920fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 16930fcb78c2SRolf Eike Beer * @wq: workqueue to use 1694af9997e4SRandy Dunlap * @dwork: work to queue 16950fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 16960fcb78c2SRolf Eike Beer * 1697d185af30SYacine Belkadi * Return: %false if @work was already on a queue, %true otherwise. If 1698715f1300STejun Heo * @delay is zero and @dwork is idle, it will be scheduled for immediate 1699715f1300STejun Heo * execution. 17000fcb78c2SRolf Eike Beer */ 1701d4283e93STejun Heo bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 170252bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 17037a6bc1cdSVenkatesh Pallipadi { 170452bad64dSDavid Howells struct work_struct *work = &dwork->work; 1705d4283e93STejun Heo bool ret = false; 17068930cabaSTejun Heo unsigned long flags; 17078930cabaSTejun Heo 17088930cabaSTejun Heo /* read the comment in __queue_work() */ 17098930cabaSTejun Heo local_irq_save(flags); 17107a6bc1cdSVenkatesh Pallipadi 171122df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 17127beb2edfSTejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 1713d4283e93STejun Heo ret = true; 17147a6bc1cdSVenkatesh Pallipadi } 17158930cabaSTejun Heo 17168930cabaSTejun Heo local_irq_restore(flags); 17177a6bc1cdSVenkatesh Pallipadi return ret; 17187a6bc1cdSVenkatesh Pallipadi } 1719ad7b1f84SMarc Dionne EXPORT_SYMBOL(queue_delayed_work_on); 17201da177e4SLinus Torvalds 1721c8e55f36STejun Heo /** 17228376fe22STejun Heo * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 17238376fe22STejun Heo * @cpu: CPU number to execute work on 17248376fe22STejun Heo * @wq: workqueue to use 17258376fe22STejun Heo * @dwork: work to queue 17268376fe22STejun Heo * @delay: number of jiffies to wait before queueing 17278376fe22STejun Heo * 17288376fe22STejun Heo * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 17298376fe22STejun Heo * modify @dwork's timer so that it expires after @delay. If @delay is 17308376fe22STejun Heo * zero, @work is guaranteed to be scheduled immediately regardless of its 17318376fe22STejun Heo * current state. 17328376fe22STejun Heo * 1733d185af30SYacine Belkadi * Return: %false if @dwork was idle and queued, %true if @dwork was 17348376fe22STejun Heo * pending and its timer was modified. 17358376fe22STejun Heo * 1736e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 17378376fe22STejun Heo * See try_to_grab_pending() for details. 17388376fe22STejun Heo */ 17398376fe22STejun Heo bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 17408376fe22STejun Heo struct delayed_work *dwork, unsigned long delay) 17418376fe22STejun Heo { 17428376fe22STejun Heo unsigned long flags; 17438376fe22STejun Heo int ret; 17448376fe22STejun Heo 17458376fe22STejun Heo do { 17468376fe22STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 17478376fe22STejun Heo } while (unlikely(ret == -EAGAIN)); 17488376fe22STejun Heo 17498376fe22STejun Heo if (likely(ret >= 0)) { 17508376fe22STejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 17518376fe22STejun Heo local_irq_restore(flags); 17528376fe22STejun Heo } 17538376fe22STejun Heo 17548376fe22STejun Heo /* -ENOENT from try_to_grab_pending() becomes %true */ 17558376fe22STejun Heo return ret; 17568376fe22STejun Heo } 17578376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work_on); 17588376fe22STejun Heo 175905f0fe6bSTejun Heo static void rcu_work_rcufn(struct rcu_head *rcu) 176005f0fe6bSTejun Heo { 176105f0fe6bSTejun Heo struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu); 176205f0fe6bSTejun Heo 176305f0fe6bSTejun Heo /* read the comment in __queue_work() */ 176405f0fe6bSTejun Heo local_irq_disable(); 176505f0fe6bSTejun Heo __queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work); 176605f0fe6bSTejun Heo local_irq_enable(); 176705f0fe6bSTejun Heo } 176805f0fe6bSTejun Heo 176905f0fe6bSTejun Heo /** 177005f0fe6bSTejun Heo * queue_rcu_work - queue work after a RCU grace period 177105f0fe6bSTejun Heo * @wq: workqueue to use 177205f0fe6bSTejun Heo * @rwork: work to queue 177305f0fe6bSTejun Heo * 177405f0fe6bSTejun Heo * Return: %false if @rwork was already pending, %true otherwise. Note 177505f0fe6bSTejun Heo * that a full RCU grace period is guaranteed only after a %true return. 1776bf393fd4SBart Van Assche * While @rwork is guaranteed to be executed after a %false return, the 177705f0fe6bSTejun Heo * execution may happen before a full RCU grace period has passed. 177805f0fe6bSTejun Heo */ 177905f0fe6bSTejun Heo bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) 178005f0fe6bSTejun Heo { 178105f0fe6bSTejun Heo struct work_struct *work = &rwork->work; 178205f0fe6bSTejun Heo 178305f0fe6bSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 178405f0fe6bSTejun Heo rwork->wq = wq; 1785a7e30c0eSUladzislau Rezki call_rcu_hurry(&rwork->rcu, rcu_work_rcufn); 178605f0fe6bSTejun Heo return true; 178705f0fe6bSTejun Heo } 178805f0fe6bSTejun Heo 178905f0fe6bSTejun Heo return false; 179005f0fe6bSTejun Heo } 179105f0fe6bSTejun Heo EXPORT_SYMBOL(queue_rcu_work); 179205f0fe6bSTejun Heo 17938376fe22STejun Heo /** 1794c8e55f36STejun Heo * worker_enter_idle - enter idle state 1795c8e55f36STejun Heo * @worker: worker which is entering idle state 1796c8e55f36STejun Heo * 1797c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1798c8e55f36STejun Heo * necessary. 1799c8e55f36STejun Heo * 1800c8e55f36STejun Heo * LOCKING: 1801a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 1802c8e55f36STejun Heo */ 1803c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 18041da177e4SLinus Torvalds { 1805bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1806c8e55f36STejun Heo 18076183c009STejun Heo if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || 18086183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->entry) && 18096183c009STejun Heo (worker->hentry.next || worker->hentry.pprev))) 18106183c009STejun Heo return; 1811c8e55f36STejun Heo 1812051e1850SLai Jiangshan /* can't use worker_set_flags(), also called from create_worker() */ 1813cb444766STejun Heo worker->flags |= WORKER_IDLE; 1814bd7bdd43STejun Heo pool->nr_idle++; 1815e22bee78STejun Heo worker->last_active = jiffies; 1816c8e55f36STejun Heo 1817c8e55f36STejun Heo /* idle_list is LIFO */ 1818bd7bdd43STejun Heo list_add(&worker->entry, &pool->idle_list); 1819db7bccf4STejun Heo 182063d95a91STejun Heo if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 1821628c78e7STejun Heo mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 1822cb444766STejun Heo 1823989442d7SLai Jiangshan /* Sanity check nr_running. */ 1824bc35f7efSLai Jiangshan WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running); 1825c8e55f36STejun Heo } 1826c8e55f36STejun Heo 1827c8e55f36STejun Heo /** 1828c8e55f36STejun Heo * worker_leave_idle - leave idle state 1829c8e55f36STejun Heo * @worker: worker which is leaving idle state 1830c8e55f36STejun Heo * 1831c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1832c8e55f36STejun Heo * 1833c8e55f36STejun Heo * LOCKING: 1834a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 1835c8e55f36STejun Heo */ 1836c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1837c8e55f36STejun Heo { 1838bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1839c8e55f36STejun Heo 18406183c009STejun Heo if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) 18416183c009STejun Heo return; 1842d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1843bd7bdd43STejun Heo pool->nr_idle--; 1844c8e55f36STejun Heo list_del_init(&worker->entry); 1845c8e55f36STejun Heo } 1846c8e55f36STejun Heo 1847f7537df5SLai Jiangshan static struct worker *alloc_worker(int node) 1848c34056a3STejun Heo { 1849c34056a3STejun Heo struct worker *worker; 1850c34056a3STejun Heo 1851f7537df5SLai Jiangshan worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); 1852c8e55f36STejun Heo if (worker) { 1853c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1854affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1855da028469SLai Jiangshan INIT_LIST_HEAD(&worker->node); 1856e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1857e22bee78STejun Heo worker->flags = WORKER_PREP; 1858c8e55f36STejun Heo } 1859c34056a3STejun Heo return worker; 1860c34056a3STejun Heo } 1861c34056a3STejun Heo 1862c34056a3STejun Heo /** 18634736cbf7SLai Jiangshan * worker_attach_to_pool() - attach a worker to a pool 18644736cbf7SLai Jiangshan * @worker: worker to be attached 18654736cbf7SLai Jiangshan * @pool: the target pool 18664736cbf7SLai Jiangshan * 18674736cbf7SLai Jiangshan * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and 18684736cbf7SLai Jiangshan * cpu-binding of @worker are kept coordinated with the pool across 18694736cbf7SLai Jiangshan * cpu-[un]hotplugs. 18704736cbf7SLai Jiangshan */ 18714736cbf7SLai Jiangshan static void worker_attach_to_pool(struct worker *worker, 18724736cbf7SLai Jiangshan struct worker_pool *pool) 18734736cbf7SLai Jiangshan { 18741258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 18754736cbf7SLai Jiangshan 18764736cbf7SLai Jiangshan /* 18771258fae7STejun Heo * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains 18781258fae7STejun Heo * stable across this function. See the comments above the flag 18791258fae7STejun Heo * definition for details. 18804736cbf7SLai Jiangshan */ 18814736cbf7SLai Jiangshan if (pool->flags & POOL_DISASSOCIATED) 18824736cbf7SLai Jiangshan worker->flags |= WORKER_UNBOUND; 18835c25b5ffSPeter Zijlstra else 18845c25b5ffSPeter Zijlstra kthread_set_per_cpu(worker->task, pool->cpu); 18854736cbf7SLai Jiangshan 1886640f17c8SPeter Zijlstra if (worker->rescue_wq) 1887640f17c8SPeter Zijlstra set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); 1888640f17c8SPeter Zijlstra 18894736cbf7SLai Jiangshan list_add_tail(&worker->node, &pool->workers); 1890a2d812a2STejun Heo worker->pool = pool; 18914736cbf7SLai Jiangshan 18921258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 18934736cbf7SLai Jiangshan } 18944736cbf7SLai Jiangshan 18954736cbf7SLai Jiangshan /** 189660f5a4bcSLai Jiangshan * worker_detach_from_pool() - detach a worker from its pool 189760f5a4bcSLai Jiangshan * @worker: worker which is attached to its pool 189860f5a4bcSLai Jiangshan * 18994736cbf7SLai Jiangshan * Undo the attaching which had been done in worker_attach_to_pool(). The 19004736cbf7SLai Jiangshan * caller worker shouldn't access to the pool after detached except it has 19014736cbf7SLai Jiangshan * other reference to the pool. 190260f5a4bcSLai Jiangshan */ 1903a2d812a2STejun Heo static void worker_detach_from_pool(struct worker *worker) 190460f5a4bcSLai Jiangshan { 1905a2d812a2STejun Heo struct worker_pool *pool = worker->pool; 190660f5a4bcSLai Jiangshan struct completion *detach_completion = NULL; 190760f5a4bcSLai Jiangshan 19081258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 1909a2d812a2STejun Heo 19105c25b5ffSPeter Zijlstra kthread_set_per_cpu(worker->task, -1); 1911da028469SLai Jiangshan list_del(&worker->node); 1912a2d812a2STejun Heo worker->pool = NULL; 1913a2d812a2STejun Heo 1914e02b9312SValentin Schneider if (list_empty(&pool->workers) && list_empty(&pool->dying_workers)) 191560f5a4bcSLai Jiangshan detach_completion = pool->detach_completion; 19161258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 191760f5a4bcSLai Jiangshan 1918b62c0751SLai Jiangshan /* clear leftover flags without pool->lock after it is detached */ 1919b62c0751SLai Jiangshan worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); 1920b62c0751SLai Jiangshan 192160f5a4bcSLai Jiangshan if (detach_completion) 192260f5a4bcSLai Jiangshan complete(detach_completion); 192360f5a4bcSLai Jiangshan } 192460f5a4bcSLai Jiangshan 192560f5a4bcSLai Jiangshan /** 1926c34056a3STejun Heo * create_worker - create a new workqueue worker 192763d95a91STejun Heo * @pool: pool the new worker will belong to 1928c34056a3STejun Heo * 1929051e1850SLai Jiangshan * Create and start a new worker which is attached to @pool. 1930c34056a3STejun Heo * 1931c34056a3STejun Heo * CONTEXT: 1932c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1933c34056a3STejun Heo * 1934d185af30SYacine Belkadi * Return: 1935c34056a3STejun Heo * Pointer to the newly created worker. 1936c34056a3STejun Heo */ 1937bc2ae0f5STejun Heo static struct worker *create_worker(struct worker_pool *pool) 1938c34056a3STejun Heo { 1939e441b56fSZhen Lei struct worker *worker; 1940e441b56fSZhen Lei int id; 1941e3c916a4STejun Heo char id_buf[16]; 1942c34056a3STejun Heo 19437cda9aaeSLai Jiangshan /* ID is needed to determine kthread name */ 1944e441b56fSZhen Lei id = ida_alloc(&pool->worker_ida, GFP_KERNEL); 19453f0ea0b8SPetr Mladek if (id < 0) { 19463f0ea0b8SPetr Mladek pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n", 19473f0ea0b8SPetr Mladek ERR_PTR(id)); 1948e441b56fSZhen Lei return NULL; 19493f0ea0b8SPetr Mladek } 1950c34056a3STejun Heo 1951f7537df5SLai Jiangshan worker = alloc_worker(pool->node); 19523f0ea0b8SPetr Mladek if (!worker) { 19533f0ea0b8SPetr Mladek pr_err_once("workqueue: Failed to allocate a worker\n"); 1954c34056a3STejun Heo goto fail; 19553f0ea0b8SPetr Mladek } 1956c34056a3STejun Heo 1957c34056a3STejun Heo worker->id = id; 1958c34056a3STejun Heo 195929c91e99STejun Heo if (pool->cpu >= 0) 1960e3c916a4STejun Heo snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, 1961e3c916a4STejun Heo pool->attrs->nice < 0 ? "H" : ""); 1962f3421797STejun Heo else 1963e3c916a4STejun Heo snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); 1964e3c916a4STejun Heo 1965f3f90ad4STejun Heo worker->task = kthread_create_on_node(worker_thread, worker, pool->node, 1966e3c916a4STejun Heo "kworker/%s", id_buf); 19673f0ea0b8SPetr Mladek if (IS_ERR(worker->task)) { 196860f54038SPetr Mladek if (PTR_ERR(worker->task) == -EINTR) { 196960f54038SPetr Mladek pr_err("workqueue: Interrupted when creating a worker thread \"kworker/%s\"\n", 197060f54038SPetr Mladek id_buf); 197160f54038SPetr Mladek } else { 19723f0ea0b8SPetr Mladek pr_err_once("workqueue: Failed to create a worker thread: %pe", 19733f0ea0b8SPetr Mladek worker->task); 197460f54038SPetr Mladek } 1975c34056a3STejun Heo goto fail; 19763f0ea0b8SPetr Mladek } 1977c34056a3STejun Heo 197891151228SOleg Nesterov set_user_nice(worker->task, pool->attrs->nice); 197925834c73SPeter Zijlstra kthread_bind_mask(worker->task, pool->attrs->cpumask); 198091151228SOleg Nesterov 1981da028469SLai Jiangshan /* successful, attach the worker to the pool */ 19824736cbf7SLai Jiangshan worker_attach_to_pool(worker, pool); 1983822d8405STejun Heo 1984051e1850SLai Jiangshan /* start the newly created worker */ 1985a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 1986051e1850SLai Jiangshan worker->pool->nr_workers++; 1987051e1850SLai Jiangshan worker_enter_idle(worker); 1988051e1850SLai Jiangshan wake_up_process(worker->task); 1989a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 1990051e1850SLai Jiangshan 1991c34056a3STejun Heo return worker; 1992822d8405STejun Heo 1993c34056a3STejun Heo fail: 1994e441b56fSZhen Lei ida_free(&pool->worker_ida, id); 1995c34056a3STejun Heo kfree(worker); 1996c34056a3STejun Heo return NULL; 1997c34056a3STejun Heo } 1998c34056a3STejun Heo 1999793777bcSValentin Schneider static void unbind_worker(struct worker *worker) 2000793777bcSValentin Schneider { 2001793777bcSValentin Schneider lockdep_assert_held(&wq_pool_attach_mutex); 2002793777bcSValentin Schneider 2003793777bcSValentin Schneider kthread_set_per_cpu(worker->task, -1); 2004793777bcSValentin Schneider if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) 2005793777bcSValentin Schneider WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0); 2006793777bcSValentin Schneider else 2007793777bcSValentin Schneider WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); 2008793777bcSValentin Schneider } 2009793777bcSValentin Schneider 2010e02b9312SValentin Schneider static void wake_dying_workers(struct list_head *cull_list) 2011e02b9312SValentin Schneider { 2012e02b9312SValentin Schneider struct worker *worker, *tmp; 2013e02b9312SValentin Schneider 2014e02b9312SValentin Schneider list_for_each_entry_safe(worker, tmp, cull_list, entry) { 2015e02b9312SValentin Schneider list_del_init(&worker->entry); 2016e02b9312SValentin Schneider unbind_worker(worker); 2017e02b9312SValentin Schneider /* 2018e02b9312SValentin Schneider * If the worker was somehow already running, then it had to be 2019e02b9312SValentin Schneider * in pool->idle_list when set_worker_dying() happened or we 2020e02b9312SValentin Schneider * wouldn't have gotten here. 2021c34056a3STejun Heo * 2022e02b9312SValentin Schneider * Thus, the worker must either have observed the WORKER_DIE 2023e02b9312SValentin Schneider * flag, or have set its state to TASK_IDLE. Either way, the 2024e02b9312SValentin Schneider * below will be observed by the worker and is safe to do 2025e02b9312SValentin Schneider * outside of pool->lock. 2026e02b9312SValentin Schneider */ 2027e02b9312SValentin Schneider wake_up_process(worker->task); 2028e02b9312SValentin Schneider } 2029e02b9312SValentin Schneider } 2030e02b9312SValentin Schneider 2031e02b9312SValentin Schneider /** 2032e02b9312SValentin Schneider * set_worker_dying - Tag a worker for destruction 2033e02b9312SValentin Schneider * @worker: worker to be destroyed 2034e02b9312SValentin Schneider * @list: transfer worker away from its pool->idle_list and into list 2035e02b9312SValentin Schneider * 2036e02b9312SValentin Schneider * Tag @worker for destruction and adjust @pool stats accordingly. The worker 2037e02b9312SValentin Schneider * should be idle. 2038c8e55f36STejun Heo * 2039c8e55f36STejun Heo * CONTEXT: 2040a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 2041c34056a3STejun Heo */ 2042e02b9312SValentin Schneider static void set_worker_dying(struct worker *worker, struct list_head *list) 2043c34056a3STejun Heo { 2044bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2045c34056a3STejun Heo 2046cd549687STejun Heo lockdep_assert_held(&pool->lock); 2047e02b9312SValentin Schneider lockdep_assert_held(&wq_pool_attach_mutex); 2048cd549687STejun Heo 2049c34056a3STejun Heo /* sanity check frenzy */ 20506183c009STejun Heo if (WARN_ON(worker->current_work) || 205173eb7fe7SLai Jiangshan WARN_ON(!list_empty(&worker->scheduled)) || 205273eb7fe7SLai Jiangshan WARN_ON(!(worker->flags & WORKER_IDLE))) 20536183c009STejun Heo return; 2054c34056a3STejun Heo 2055bd7bdd43STejun Heo pool->nr_workers--; 2056bd7bdd43STejun Heo pool->nr_idle--; 2057c8e55f36STejun Heo 2058cb444766STejun Heo worker->flags |= WORKER_DIE; 2059e02b9312SValentin Schneider 2060e02b9312SValentin Schneider list_move(&worker->entry, list); 2061e02b9312SValentin Schneider list_move(&worker->node, &pool->dying_workers); 2062c34056a3STejun Heo } 2063c34056a3STejun Heo 20643f959aa3SValentin Schneider /** 20653f959aa3SValentin Schneider * idle_worker_timeout - check if some idle workers can now be deleted. 20663f959aa3SValentin Schneider * @t: The pool's idle_timer that just expired 20673f959aa3SValentin Schneider * 20683f959aa3SValentin Schneider * The timer is armed in worker_enter_idle(). Note that it isn't disarmed in 20693f959aa3SValentin Schneider * worker_leave_idle(), as a worker flicking between idle and active while its 20703f959aa3SValentin Schneider * pool is at the too_many_workers() tipping point would cause too much timer 20713f959aa3SValentin Schneider * housekeeping overhead. Since IDLE_WORKER_TIMEOUT is long enough, we just let 20723f959aa3SValentin Schneider * it expire and re-evaluate things from there. 20733f959aa3SValentin Schneider */ 207432a6c723SKees Cook static void idle_worker_timeout(struct timer_list *t) 2075e22bee78STejun Heo { 207632a6c723SKees Cook struct worker_pool *pool = from_timer(pool, t, idle_timer); 20773f959aa3SValentin Schneider bool do_cull = false; 20783f959aa3SValentin Schneider 20793f959aa3SValentin Schneider if (work_pending(&pool->idle_cull_work)) 20803f959aa3SValentin Schneider return; 20813f959aa3SValentin Schneider 20823f959aa3SValentin Schneider raw_spin_lock_irq(&pool->lock); 20833f959aa3SValentin Schneider 20843f959aa3SValentin Schneider if (too_many_workers(pool)) { 20853f959aa3SValentin Schneider struct worker *worker; 20863f959aa3SValentin Schneider unsigned long expires; 20873f959aa3SValentin Schneider 20883f959aa3SValentin Schneider /* idle_list is kept in LIFO order, check the last one */ 20893f959aa3SValentin Schneider worker = list_entry(pool->idle_list.prev, struct worker, entry); 20903f959aa3SValentin Schneider expires = worker->last_active + IDLE_WORKER_TIMEOUT; 20913f959aa3SValentin Schneider do_cull = !time_before(jiffies, expires); 20923f959aa3SValentin Schneider 20933f959aa3SValentin Schneider if (!do_cull) 20943f959aa3SValentin Schneider mod_timer(&pool->idle_timer, expires); 20953f959aa3SValentin Schneider } 20963f959aa3SValentin Schneider raw_spin_unlock_irq(&pool->lock); 20973f959aa3SValentin Schneider 20983f959aa3SValentin Schneider if (do_cull) 20993f959aa3SValentin Schneider queue_work(system_unbound_wq, &pool->idle_cull_work); 21003f959aa3SValentin Schneider } 21013f959aa3SValentin Schneider 21023f959aa3SValentin Schneider /** 21033f959aa3SValentin Schneider * idle_cull_fn - cull workers that have been idle for too long. 21043f959aa3SValentin Schneider * @work: the pool's work for handling these idle workers 21053f959aa3SValentin Schneider * 21063f959aa3SValentin Schneider * This goes through a pool's idle workers and gets rid of those that have been 21073f959aa3SValentin Schneider * idle for at least IDLE_WORKER_TIMEOUT seconds. 2108e02b9312SValentin Schneider * 2109e02b9312SValentin Schneider * We don't want to disturb isolated CPUs because of a pcpu kworker being 2110e02b9312SValentin Schneider * culled, so this also resets worker affinity. This requires a sleepable 2111e02b9312SValentin Schneider * context, hence the split between timer callback and work item. 21123f959aa3SValentin Schneider */ 21133f959aa3SValentin Schneider static void idle_cull_fn(struct work_struct *work) 21143f959aa3SValentin Schneider { 21153f959aa3SValentin Schneider struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work); 2116e02b9312SValentin Schneider struct list_head cull_list; 2117e22bee78STejun Heo 2118e02b9312SValentin Schneider INIT_LIST_HEAD(&cull_list); 2119e02b9312SValentin Schneider /* 2120e02b9312SValentin Schneider * Grabbing wq_pool_attach_mutex here ensures an already-running worker 2121e02b9312SValentin Schneider * cannot proceed beyong worker_detach_from_pool() in its self-destruct 2122e02b9312SValentin Schneider * path. This is required as a previously-preempted worker could run after 2123e02b9312SValentin Schneider * set_worker_dying() has happened but before wake_dying_workers() did. 2124e02b9312SValentin Schneider */ 2125e02b9312SValentin Schneider mutex_lock(&wq_pool_attach_mutex); 2126a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2127e22bee78STejun Heo 21283347fc9fSLai Jiangshan while (too_many_workers(pool)) { 2129e22bee78STejun Heo struct worker *worker; 2130e22bee78STejun Heo unsigned long expires; 2131e22bee78STejun Heo 213263d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 2133e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 2134e22bee78STejun Heo 21353347fc9fSLai Jiangshan if (time_before(jiffies, expires)) { 213663d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 21373347fc9fSLai Jiangshan break; 2138e22bee78STejun Heo } 21393347fc9fSLai Jiangshan 2140e02b9312SValentin Schneider set_worker_dying(worker, &cull_list); 2141e22bee78STejun Heo } 2142e22bee78STejun Heo 2143a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2144e02b9312SValentin Schneider wake_dying_workers(&cull_list); 2145e02b9312SValentin Schneider mutex_unlock(&wq_pool_attach_mutex); 2146e22bee78STejun Heo } 2147e22bee78STejun Heo 2148493a1724STejun Heo static void send_mayday(struct work_struct *work) 2149e22bee78STejun Heo { 2150112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2151112202d9STejun Heo struct workqueue_struct *wq = pwq->wq; 2152493a1724STejun Heo 21532e109a28STejun Heo lockdep_assert_held(&wq_mayday_lock); 2154e22bee78STejun Heo 2155493008a8STejun Heo if (!wq->rescuer) 2156493a1724STejun Heo return; 2157e22bee78STejun Heo 2158e22bee78STejun Heo /* mayday mayday mayday */ 2159493a1724STejun Heo if (list_empty(&pwq->mayday_node)) { 216077668c8bSLai Jiangshan /* 216177668c8bSLai Jiangshan * If @pwq is for an unbound wq, its base ref may be put at 216277668c8bSLai Jiangshan * any time due to an attribute change. Pin @pwq until the 216377668c8bSLai Jiangshan * rescuer is done with it. 216477668c8bSLai Jiangshan */ 216577668c8bSLai Jiangshan get_pwq(pwq); 2166493a1724STejun Heo list_add_tail(&pwq->mayday_node, &wq->maydays); 2167e22bee78STejun Heo wake_up_process(wq->rescuer->task); 2168493a1724STejun Heo } 2169e22bee78STejun Heo } 2170e22bee78STejun Heo 217132a6c723SKees Cook static void pool_mayday_timeout(struct timer_list *t) 2172e22bee78STejun Heo { 217332a6c723SKees Cook struct worker_pool *pool = from_timer(pool, t, mayday_timer); 2174e22bee78STejun Heo struct work_struct *work; 2175e22bee78STejun Heo 2176a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2177a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */ 2178e22bee78STejun Heo 217963d95a91STejun Heo if (need_to_create_worker(pool)) { 2180e22bee78STejun Heo /* 2181e22bee78STejun Heo * We've been trying to create a new worker but 2182e22bee78STejun Heo * haven't been successful. We might be hitting an 2183e22bee78STejun Heo * allocation deadlock. Send distress signals to 2184e22bee78STejun Heo * rescuers. 2185e22bee78STejun Heo */ 218663d95a91STejun Heo list_for_each_entry(work, &pool->worklist, entry) 2187e22bee78STejun Heo send_mayday(work); 2188e22bee78STejun Heo } 2189e22bee78STejun Heo 2190a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&wq_mayday_lock); 2191a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2192e22bee78STejun Heo 219363d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 2194e22bee78STejun Heo } 2195e22bee78STejun Heo 2196e22bee78STejun Heo /** 2197e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 219863d95a91STejun Heo * @pool: pool to create a new worker for 2199e22bee78STejun Heo * 220063d95a91STejun Heo * Create a new worker for @pool if necessary. @pool is guaranteed to 2201e22bee78STejun Heo * have at least one idle worker on return from this function. If 2202e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 220363d95a91STejun Heo * sent to all rescuers with works scheduled on @pool to resolve 2204e22bee78STejun Heo * possible allocation deadlock. 2205e22bee78STejun Heo * 2206c5aa87bbSTejun Heo * On return, need_to_create_worker() is guaranteed to be %false and 2207c5aa87bbSTejun Heo * may_start_working() %true. 2208e22bee78STejun Heo * 2209e22bee78STejun Heo * LOCKING: 2210a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 2211e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 2212e22bee78STejun Heo * manager. 2213e22bee78STejun Heo */ 221429187a9eSTejun Heo static void maybe_create_worker(struct worker_pool *pool) 2215d565ed63STejun Heo __releases(&pool->lock) 2216d565ed63STejun Heo __acquires(&pool->lock) 2217e22bee78STejun Heo { 2218e22bee78STejun Heo restart: 2219a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 22209f9c2364STejun Heo 2221e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 222263d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 2223e22bee78STejun Heo 2224e22bee78STejun Heo while (true) { 2225051e1850SLai Jiangshan if (create_worker(pool) || !need_to_create_worker(pool)) 2226e22bee78STejun Heo break; 2227e22bee78STejun Heo 2228e212f361SLai Jiangshan schedule_timeout_interruptible(CREATE_COOLDOWN); 22299f9c2364STejun Heo 223063d95a91STejun Heo if (!need_to_create_worker(pool)) 2231e22bee78STejun Heo break; 2232e22bee78STejun Heo } 2233e22bee78STejun Heo 223463d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 2235a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2236051e1850SLai Jiangshan /* 2237051e1850SLai Jiangshan * This is necessary even after a new worker was just successfully 2238051e1850SLai Jiangshan * created as @pool->lock was dropped and the new worker might have 2239051e1850SLai Jiangshan * already become busy. 2240051e1850SLai Jiangshan */ 224163d95a91STejun Heo if (need_to_create_worker(pool)) 2242e22bee78STejun Heo goto restart; 2243e22bee78STejun Heo } 2244e22bee78STejun Heo 2245e22bee78STejun Heo /** 2246e22bee78STejun Heo * manage_workers - manage worker pool 2247e22bee78STejun Heo * @worker: self 2248e22bee78STejun Heo * 2249706026c2STejun Heo * Assume the manager role and manage the worker pool @worker belongs 2250e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 2251706026c2STejun Heo * pool. The exclusion is handled automatically by this function. 2252e22bee78STejun Heo * 2253e22bee78STejun Heo * The caller can safely start processing works on false return. On 2254e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 2255e22bee78STejun Heo * and may_start_working() is true. 2256e22bee78STejun Heo * 2257e22bee78STejun Heo * CONTEXT: 2258a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 2259e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 2260e22bee78STejun Heo * 2261d185af30SYacine Belkadi * Return: 226229187a9eSTejun Heo * %false if the pool doesn't need management and the caller can safely 226329187a9eSTejun Heo * start processing works, %true if management function was performed and 226429187a9eSTejun Heo * the conditions that the caller verified before calling the function may 226529187a9eSTejun Heo * no longer be true. 2266e22bee78STejun Heo */ 2267e22bee78STejun Heo static bool manage_workers(struct worker *worker) 2268e22bee78STejun Heo { 226963d95a91STejun Heo struct worker_pool *pool = worker->pool; 2270e22bee78STejun Heo 2271692b4825STejun Heo if (pool->flags & POOL_MANAGER_ACTIVE) 227229187a9eSTejun Heo return false; 2273692b4825STejun Heo 2274692b4825STejun Heo pool->flags |= POOL_MANAGER_ACTIVE; 22752607d7a6STejun Heo pool->manager = worker; 2276e22bee78STejun Heo 227729187a9eSTejun Heo maybe_create_worker(pool); 2278e22bee78STejun Heo 22792607d7a6STejun Heo pool->manager = NULL; 2280692b4825STejun Heo pool->flags &= ~POOL_MANAGER_ACTIVE; 2281d8bb65abSSebastian Andrzej Siewior rcuwait_wake_up(&manager_wait); 228229187a9eSTejun Heo return true; 2283e22bee78STejun Heo } 2284e22bee78STejun Heo 2285a62428c0STejun Heo /** 2286a62428c0STejun Heo * process_one_work - process single work 2287c34056a3STejun Heo * @worker: self 2288a62428c0STejun Heo * @work: work to process 2289a62428c0STejun Heo * 2290a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 2291a62428c0STejun Heo * process a single work including synchronization against and 2292a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 2293a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 2294a62428c0STejun Heo * call this function to process a work. 2295a62428c0STejun Heo * 2296a62428c0STejun Heo * CONTEXT: 2297a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) which is released and regrabbed. 2298a62428c0STejun Heo */ 2299c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 2300d565ed63STejun Heo __releases(&pool->lock) 2301d565ed63STejun Heo __acquires(&pool->lock) 23021da177e4SLinus Torvalds { 2303112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2304bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2305112202d9STejun Heo bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; 2306c4560c2cSLai Jiangshan unsigned long work_data; 23077e11629dSTejun Heo struct worker *collision; 23084e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 23094e6045f1SJohannes Berg /* 2310a62428c0STejun Heo * It is permissible to free the struct work_struct from 2311a62428c0STejun Heo * inside the function that is called from it, this we need to 2312a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 2313a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 2314a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 23154e6045f1SJohannes Berg */ 23164d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 23174d82a1deSPeter Zijlstra 23184d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 23194e6045f1SJohannes Berg #endif 2320807407c0SLai Jiangshan /* ensure we're on the correct CPU */ 232185327af6SLai Jiangshan WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 2322ec22ca5eSTejun Heo raw_smp_processor_id() != pool->cpu); 232325511a47STejun Heo 23247e11629dSTejun Heo /* 23257e11629dSTejun Heo * A single work shouldn't be executed concurrently by 23267e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 23277e11629dSTejun Heo * already processing the work. If so, defer the work to the 23287e11629dSTejun Heo * currently executing one. 23297e11629dSTejun Heo */ 2330c9e7cf27STejun Heo collision = find_worker_executing_work(pool, work); 23317e11629dSTejun Heo if (unlikely(collision)) { 23327e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 23337e11629dSTejun Heo return; 23347e11629dSTejun Heo } 23351da177e4SLinus Torvalds 23368930cabaSTejun Heo /* claim and dequeue */ 23371da177e4SLinus Torvalds debug_work_deactivate(work); 2338c9e7cf27STejun Heo hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); 2339c34056a3STejun Heo worker->current_work = work; 2340a2c1c57bSTejun Heo worker->current_func = work->func; 2341112202d9STejun Heo worker->current_pwq = pwq; 2342c4560c2cSLai Jiangshan work_data = *work_data_bits(work); 2343d812796eSLai Jiangshan worker->current_color = get_work_color(work_data); 23447a22ad75STejun Heo 23458bf89593STejun Heo /* 23468bf89593STejun Heo * Record wq name for cmdline and debug reporting, may get 23478bf89593STejun Heo * overridden through set_worker_desc(). 23488bf89593STejun Heo */ 23498bf89593STejun Heo strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN); 23508bf89593STejun Heo 2351a62428c0STejun Heo list_del_init(&work->entry); 2352a62428c0STejun Heo 2353649027d7STejun Heo /* 2354228f1d00SLai Jiangshan * CPU intensive works don't participate in concurrency management. 2355228f1d00SLai Jiangshan * They're the scheduler's responsibility. This takes @worker out 2356228f1d00SLai Jiangshan * of concurrency management and the next code block will chain 2357228f1d00SLai Jiangshan * execution of the pending work items. 2358fb0e7bebSTejun Heo */ 2359fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2360228f1d00SLai Jiangshan worker_set_flags(worker, WORKER_CPU_INTENSIVE); 2361fb0e7bebSTejun Heo 2362974271c4STejun Heo /* 2363a489a03eSLai Jiangshan * Wake up another worker if necessary. The condition is always 2364a489a03eSLai Jiangshan * false for normal per-cpu workers since nr_running would always 2365a489a03eSLai Jiangshan * be >= 1 at this point. This is used to chain execution of the 2366a489a03eSLai Jiangshan * pending work items for WORKER_NOT_RUNNING workers such as the 2367228f1d00SLai Jiangshan * UNBOUND and CPU_INTENSIVE ones. 2368974271c4STejun Heo */ 2369a489a03eSLai Jiangshan if (need_more_worker(pool)) 237063d95a91STejun Heo wake_up_worker(pool); 2371974271c4STejun Heo 23728930cabaSTejun Heo /* 23737c3eed5cSTejun Heo * Record the last pool and clear PENDING which should be the last 2374d565ed63STejun Heo * update to @work. Also, do this inside @pool->lock so that 237523657bb1STejun Heo * PENDING and queued state changes happen together while IRQ is 237623657bb1STejun Heo * disabled. 23778930cabaSTejun Heo */ 23787c3eed5cSTejun Heo set_work_pool_and_clear_pending(work, pool->id); 23791da177e4SLinus Torvalds 2380a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2381365970a1SDavid Howells 2382a1d14934SPeter Zijlstra lock_map_acquire(&pwq->wq->lockdep_map); 23833295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 2384e6f3faa7SPeter Zijlstra /* 2385f52be570SPeter Zijlstra * Strictly speaking we should mark the invariant state without holding 2386f52be570SPeter Zijlstra * any locks, that is, before these two lock_map_acquire()'s. 2387e6f3faa7SPeter Zijlstra * 2388e6f3faa7SPeter Zijlstra * However, that would result in: 2389e6f3faa7SPeter Zijlstra * 2390e6f3faa7SPeter Zijlstra * A(W1) 2391e6f3faa7SPeter Zijlstra * WFC(C) 2392e6f3faa7SPeter Zijlstra * A(W1) 2393e6f3faa7SPeter Zijlstra * C(C) 2394e6f3faa7SPeter Zijlstra * 2395e6f3faa7SPeter Zijlstra * Which would create W1->C->W1 dependencies, even though there is no 2396e6f3faa7SPeter Zijlstra * actual deadlock possible. There are two solutions, using a 2397e6f3faa7SPeter Zijlstra * read-recursive acquire on the work(queue) 'locks', but this will then 2398f52be570SPeter Zijlstra * hit the lockdep limitation on recursive locks, or simply discard 2399e6f3faa7SPeter Zijlstra * these locks. 2400e6f3faa7SPeter Zijlstra * 2401e6f3faa7SPeter Zijlstra * AFAICT there is no possible deadlock scenario between the 2402e6f3faa7SPeter Zijlstra * flush_work() and complete() primitives (except for single-threaded 2403e6f3faa7SPeter Zijlstra * workqueues), so hiding them isn't a problem. 2404e6f3faa7SPeter Zijlstra */ 2405f52be570SPeter Zijlstra lockdep_invariant_state(true); 2406e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 2407a2c1c57bSTejun Heo worker->current_func(work); 2408e36c886aSArjan van de Ven /* 2409e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 2410e36c886aSArjan van de Ven * point will only record its address. 2411e36c886aSArjan van de Ven */ 24121c5da0ecSDaniel Jordan trace_workqueue_execute_end(work, worker->current_func); 24133295f0efSIngo Molnar lock_map_release(&lockdep_map); 2414112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 24151da177e4SLinus Torvalds 2416d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 2417044c782cSValentin Ilie pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" 2418d75f773cSSakari Ailus " last function: %ps\n", 2419a2c1c57bSTejun Heo current->comm, preempt_count(), task_pid_nr(current), 2420a2c1c57bSTejun Heo worker->current_func); 2421d5abe669SPeter Zijlstra debug_show_held_locks(current); 2422d5abe669SPeter Zijlstra dump_stack(); 2423d5abe669SPeter Zijlstra } 2424d5abe669SPeter Zijlstra 2425b22ce278STejun Heo /* 2426025f50f3SSebastian Andrzej Siewior * The following prevents a kworker from hogging CPU on !PREEMPTION 2427b22ce278STejun Heo * kernels, where a requeueing work item waiting for something to 2428b22ce278STejun Heo * happen could deadlock with stop_machine as such work item could 2429b22ce278STejun Heo * indefinitely requeue itself while all other CPUs are trapped in 2430789cbbecSJoe Lawrence * stop_machine. At the same time, report a quiescent RCU state so 2431789cbbecSJoe Lawrence * the same condition doesn't freeze RCU. 2432b22ce278STejun Heo */ 2433a7e6425eSPaul E. McKenney cond_resched(); 2434b22ce278STejun Heo 2435a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2436a62428c0STejun Heo 2437fb0e7bebSTejun Heo /* clear cpu intensive status */ 2438fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2439fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 2440fb0e7bebSTejun Heo 24411b69ac6bSJohannes Weiner /* tag the worker for identification in schedule() */ 24421b69ac6bSJohannes Weiner worker->last_func = worker->current_func; 24431b69ac6bSJohannes Weiner 2444a62428c0STejun Heo /* we're done with it, release */ 244542f8570fSSasha Levin hash_del(&worker->hentry); 2446c34056a3STejun Heo worker->current_work = NULL; 2447a2c1c57bSTejun Heo worker->current_func = NULL; 2448112202d9STejun Heo worker->current_pwq = NULL; 2449d812796eSLai Jiangshan worker->current_color = INT_MAX; 2450c4560c2cSLai Jiangshan pwq_dec_nr_in_flight(pwq, work_data); 24511da177e4SLinus Torvalds } 24521da177e4SLinus Torvalds 2453affee4b2STejun Heo /** 2454affee4b2STejun Heo * process_scheduled_works - process scheduled works 2455affee4b2STejun Heo * @worker: self 2456affee4b2STejun Heo * 2457affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 2458affee4b2STejun Heo * may change while processing a work, so this function repeatedly 2459affee4b2STejun Heo * fetches a work from the top and executes it. 2460affee4b2STejun Heo * 2461affee4b2STejun Heo * CONTEXT: 2462a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock) which may be released and regrabbed 2463affee4b2STejun Heo * multiple times. 2464affee4b2STejun Heo */ 2465affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 24661da177e4SLinus Torvalds { 2467affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 2468affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 2469a62428c0STejun Heo struct work_struct, entry); 2470c34056a3STejun Heo process_one_work(worker, work); 2471a62428c0STejun Heo } 24721da177e4SLinus Torvalds } 24731da177e4SLinus Torvalds 2474197f6accSTejun Heo static void set_pf_worker(bool val) 2475197f6accSTejun Heo { 2476197f6accSTejun Heo mutex_lock(&wq_pool_attach_mutex); 2477197f6accSTejun Heo if (val) 2478197f6accSTejun Heo current->flags |= PF_WQ_WORKER; 2479197f6accSTejun Heo else 2480197f6accSTejun Heo current->flags &= ~PF_WQ_WORKER; 2481197f6accSTejun Heo mutex_unlock(&wq_pool_attach_mutex); 2482197f6accSTejun Heo } 2483197f6accSTejun Heo 24844690c4abSTejun Heo /** 24854690c4abSTejun Heo * worker_thread - the worker thread function 2486c34056a3STejun Heo * @__worker: self 24874690c4abSTejun Heo * 2488c5aa87bbSTejun Heo * The worker thread function. All workers belong to a worker_pool - 2489c5aa87bbSTejun Heo * either a per-cpu one or dynamic unbound one. These workers process all 2490c5aa87bbSTejun Heo * work items regardless of their specific target workqueue. The only 2491c5aa87bbSTejun Heo * exception is work items which belong to workqueues with a rescuer which 2492c5aa87bbSTejun Heo * will be explained in rescuer_thread(). 2493d185af30SYacine Belkadi * 2494d185af30SYacine Belkadi * Return: 0 24954690c4abSTejun Heo */ 2496c34056a3STejun Heo static int worker_thread(void *__worker) 24971da177e4SLinus Torvalds { 2498c34056a3STejun Heo struct worker *worker = __worker; 2499bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 25001da177e4SLinus Torvalds 2501e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 2502197f6accSTejun Heo set_pf_worker(true); 2503c8e55f36STejun Heo woke_up: 2504a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2505affee4b2STejun Heo 2506a9ab775bSTejun Heo /* am I supposed to die? */ 2507a9ab775bSTejun Heo if (unlikely(worker->flags & WORKER_DIE)) { 2508a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 2509197f6accSTejun Heo set_pf_worker(false); 251060f5a4bcSLai Jiangshan 251160f5a4bcSLai Jiangshan set_task_comm(worker->task, "kworker/dying"); 2512e441b56fSZhen Lei ida_free(&pool->worker_ida, worker->id); 2513a2d812a2STejun Heo worker_detach_from_pool(worker); 2514e02b9312SValentin Schneider WARN_ON_ONCE(!list_empty(&worker->entry)); 251560f5a4bcSLai Jiangshan kfree(worker); 2516c8e55f36STejun Heo return 0; 2517c8e55f36STejun Heo } 2518c8e55f36STejun Heo 2519c8e55f36STejun Heo worker_leave_idle(worker); 2520db7bccf4STejun Heo recheck: 2521e22bee78STejun Heo /* no more worker necessary? */ 252263d95a91STejun Heo if (!need_more_worker(pool)) 2523e22bee78STejun Heo goto sleep; 2524e22bee78STejun Heo 2525e22bee78STejun Heo /* do we need to manage? */ 252663d95a91STejun Heo if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 2527e22bee78STejun Heo goto recheck; 2528e22bee78STejun Heo 2529c8e55f36STejun Heo /* 2530c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 2531c8e55f36STejun Heo * preparing to process a work or actually processing it. 2532c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 2533c8e55f36STejun Heo */ 25346183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->scheduled)); 2535c8e55f36STejun Heo 2536e22bee78STejun Heo /* 2537a9ab775bSTejun Heo * Finish PREP stage. We're guaranteed to have at least one idle 2538a9ab775bSTejun Heo * worker or that someone else has already assumed the manager 2539a9ab775bSTejun Heo * role. This is where @worker starts participating in concurrency 2540a9ab775bSTejun Heo * management if applicable and concurrency management is restored 2541a9ab775bSTejun Heo * after being rebound. See rebind_workers() for details. 2542e22bee78STejun Heo */ 2543a9ab775bSTejun Heo worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); 2544e22bee78STejun Heo 2545e22bee78STejun Heo do { 2546affee4b2STejun Heo struct work_struct *work = 2547bd7bdd43STejun Heo list_first_entry(&pool->worklist, 2548affee4b2STejun Heo struct work_struct, entry); 2549affee4b2STejun Heo 255082607adcSTejun Heo pool->watchdog_ts = jiffies; 255182607adcSTejun Heo 2552c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 2553affee4b2STejun Heo /* optimization path, not strictly necessary */ 2554affee4b2STejun Heo process_one_work(worker, work); 2555affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 2556affee4b2STejun Heo process_scheduled_works(worker); 2557affee4b2STejun Heo } else { 2558c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 2559affee4b2STejun Heo process_scheduled_works(worker); 2560affee4b2STejun Heo } 256163d95a91STejun Heo } while (keep_working(pool)); 2562affee4b2STejun Heo 2563228f1d00SLai Jiangshan worker_set_flags(worker, WORKER_PREP); 2564d313dd85STejun Heo sleep: 2565c8e55f36STejun Heo /* 2566d565ed63STejun Heo * pool->lock is held and there's no work to process and no need to 2567d565ed63STejun Heo * manage, sleep. Workers are woken up only while holding 2568d565ed63STejun Heo * pool->lock or from local cpu, so setting the current state 2569d565ed63STejun Heo * before releasing pool->lock is enough to prevent losing any 2570d565ed63STejun Heo * event. 2571c8e55f36STejun Heo */ 2572c8e55f36STejun Heo worker_enter_idle(worker); 2573c5a94a61SPeter Zijlstra __set_current_state(TASK_IDLE); 2574a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 25751da177e4SLinus Torvalds schedule(); 2576c8e55f36STejun Heo goto woke_up; 25771da177e4SLinus Torvalds } 25781da177e4SLinus Torvalds 2579e22bee78STejun Heo /** 2580e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2581111c225aSTejun Heo * @__rescuer: self 2582e22bee78STejun Heo * 2583e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2584493008a8STejun Heo * workqueue which has WQ_MEM_RECLAIM set. 2585e22bee78STejun Heo * 2586706026c2STejun Heo * Regular work processing on a pool may block trying to create a new 2587e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2588e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2589e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2590e22bee78STejun Heo * the problem rescuer solves. 2591e22bee78STejun Heo * 2592706026c2STejun Heo * When such condition is possible, the pool summons rescuers of all 2593706026c2STejun Heo * workqueues which have works queued on the pool and let them process 2594e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2595e22bee78STejun Heo * 2596e22bee78STejun Heo * This should happen rarely. 2597d185af30SYacine Belkadi * 2598d185af30SYacine Belkadi * Return: 0 2599e22bee78STejun Heo */ 2600111c225aSTejun Heo static int rescuer_thread(void *__rescuer) 2601e22bee78STejun Heo { 2602111c225aSTejun Heo struct worker *rescuer = __rescuer; 2603111c225aSTejun Heo struct workqueue_struct *wq = rescuer->rescue_wq; 2604e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 26054d595b86SLai Jiangshan bool should_stop; 2606e22bee78STejun Heo 2607e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2608111c225aSTejun Heo 2609111c225aSTejun Heo /* 2610111c225aSTejun Heo * Mark rescuer as worker too. As WORKER_PREP is never cleared, it 2611111c225aSTejun Heo * doesn't participate in concurrency management. 2612111c225aSTejun Heo */ 2613197f6accSTejun Heo set_pf_worker(true); 2614e22bee78STejun Heo repeat: 2615c5a94a61SPeter Zijlstra set_current_state(TASK_IDLE); 26161da177e4SLinus Torvalds 26174d595b86SLai Jiangshan /* 26184d595b86SLai Jiangshan * By the time the rescuer is requested to stop, the workqueue 26194d595b86SLai Jiangshan * shouldn't have any work pending, but @wq->maydays may still have 26204d595b86SLai Jiangshan * pwq(s) queued. This can happen by non-rescuer workers consuming 26214d595b86SLai Jiangshan * all the work items before the rescuer got to them. Go through 26224d595b86SLai Jiangshan * @wq->maydays processing before acting on should_stop so that the 26234d595b86SLai Jiangshan * list is always empty on exit. 26244d595b86SLai Jiangshan */ 26254d595b86SLai Jiangshan should_stop = kthread_should_stop(); 26261da177e4SLinus Torvalds 2627493a1724STejun Heo /* see whether any pwq is asking for help */ 2628a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&wq_mayday_lock); 2629493a1724STejun Heo 2630493a1724STejun Heo while (!list_empty(&wq->maydays)) { 2631493a1724STejun Heo struct pool_workqueue *pwq = list_first_entry(&wq->maydays, 2632493a1724STejun Heo struct pool_workqueue, mayday_node); 2633112202d9STejun Heo struct worker_pool *pool = pwq->pool; 2634e22bee78STejun Heo struct work_struct *work, *n; 263582607adcSTejun Heo bool first = true; 2636e22bee78STejun Heo 2637e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2638493a1724STejun Heo list_del_init(&pwq->mayday_node); 2639493a1724STejun Heo 2640a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&wq_mayday_lock); 2641e22bee78STejun Heo 264251697d39SLai Jiangshan worker_attach_to_pool(rescuer, pool); 264351697d39SLai Jiangshan 2644a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 2645e22bee78STejun Heo 2646e22bee78STejun Heo /* 2647e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2648e22bee78STejun Heo * process'em. 2649e22bee78STejun Heo */ 26500479c8c5STejun Heo WARN_ON_ONCE(!list_empty(scheduled)); 265182607adcSTejun Heo list_for_each_entry_safe(work, n, &pool->worklist, entry) { 265282607adcSTejun Heo if (get_work_pwq(work) == pwq) { 265382607adcSTejun Heo if (first) 265482607adcSTejun Heo pool->watchdog_ts = jiffies; 2655e22bee78STejun Heo move_linked_works(work, scheduled, &n); 265682607adcSTejun Heo } 265782607adcSTejun Heo first = false; 265882607adcSTejun Heo } 2659e22bee78STejun Heo 2660008847f6SNeilBrown if (!list_empty(scheduled)) { 2661e22bee78STejun Heo process_scheduled_works(rescuer); 26627576958aSTejun Heo 26637576958aSTejun Heo /* 2664008847f6SNeilBrown * The above execution of rescued work items could 2665008847f6SNeilBrown * have created more to rescue through 2666f97a4a1aSLai Jiangshan * pwq_activate_first_inactive() or chained 2667008847f6SNeilBrown * queueing. Let's put @pwq back on mayday list so 2668008847f6SNeilBrown * that such back-to-back work items, which may be 2669008847f6SNeilBrown * being used to relieve memory pressure, don't 2670008847f6SNeilBrown * incur MAYDAY_INTERVAL delay inbetween. 2671008847f6SNeilBrown */ 26724f3f4cf3SLai Jiangshan if (pwq->nr_active && need_to_create_worker(pool)) { 2673a9b8a985SSebastian Andrzej Siewior raw_spin_lock(&wq_mayday_lock); 2674e66b39afSTejun Heo /* 2675e66b39afSTejun Heo * Queue iff we aren't racing destruction 2676e66b39afSTejun Heo * and somebody else hasn't queued it already. 2677e66b39afSTejun Heo */ 2678e66b39afSTejun Heo if (wq->rescuer && list_empty(&pwq->mayday_node)) { 2679008847f6SNeilBrown get_pwq(pwq); 2680e66b39afSTejun Heo list_add_tail(&pwq->mayday_node, &wq->maydays); 2681e66b39afSTejun Heo } 2682a9b8a985SSebastian Andrzej Siewior raw_spin_unlock(&wq_mayday_lock); 2683008847f6SNeilBrown } 2684008847f6SNeilBrown } 2685008847f6SNeilBrown 2686008847f6SNeilBrown /* 268777668c8bSLai Jiangshan * Put the reference grabbed by send_mayday(). @pool won't 268813b1d625SLai Jiangshan * go away while we're still attached to it. 268977668c8bSLai Jiangshan */ 269077668c8bSLai Jiangshan put_pwq(pwq); 269177668c8bSLai Jiangshan 269277668c8bSLai Jiangshan /* 2693d8ca83e6SLai Jiangshan * Leave this pool. If need_more_worker() is %true, notify a 26947576958aSTejun Heo * regular worker; otherwise, we end up with 0 concurrency 26957576958aSTejun Heo * and stalling the execution. 26967576958aSTejun Heo */ 2697d8ca83e6SLai Jiangshan if (need_more_worker(pool)) 269863d95a91STejun Heo wake_up_worker(pool); 26997576958aSTejun Heo 2700a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 270113b1d625SLai Jiangshan 2702a2d812a2STejun Heo worker_detach_from_pool(rescuer); 270313b1d625SLai Jiangshan 2704a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&wq_mayday_lock); 27051da177e4SLinus Torvalds } 27061da177e4SLinus Torvalds 2707a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&wq_mayday_lock); 2708493a1724STejun Heo 27094d595b86SLai Jiangshan if (should_stop) { 27104d595b86SLai Jiangshan __set_current_state(TASK_RUNNING); 2711197f6accSTejun Heo set_pf_worker(false); 27124d595b86SLai Jiangshan return 0; 27134d595b86SLai Jiangshan } 27144d595b86SLai Jiangshan 2715111c225aSTejun Heo /* rescuers should never participate in concurrency management */ 2716111c225aSTejun Heo WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); 2717e22bee78STejun Heo schedule(); 2718e22bee78STejun Heo goto repeat; 27191da177e4SLinus Torvalds } 27201da177e4SLinus Torvalds 2721fca839c0STejun Heo /** 2722fca839c0STejun Heo * check_flush_dependency - check for flush dependency sanity 2723fca839c0STejun Heo * @target_wq: workqueue being flushed 2724fca839c0STejun Heo * @target_work: work item being flushed (NULL for workqueue flushes) 2725fca839c0STejun Heo * 2726fca839c0STejun Heo * %current is trying to flush the whole @target_wq or @target_work on it. 2727fca839c0STejun Heo * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not 2728fca839c0STejun Heo * reclaiming memory or running on a workqueue which doesn't have 2729fca839c0STejun Heo * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to 2730fca839c0STejun Heo * a deadlock. 2731fca839c0STejun Heo */ 2732fca839c0STejun Heo static void check_flush_dependency(struct workqueue_struct *target_wq, 2733fca839c0STejun Heo struct work_struct *target_work) 2734fca839c0STejun Heo { 2735fca839c0STejun Heo work_func_t target_func = target_work ? target_work->func : NULL; 2736fca839c0STejun Heo struct worker *worker; 2737fca839c0STejun Heo 2738fca839c0STejun Heo if (target_wq->flags & WQ_MEM_RECLAIM) 2739fca839c0STejun Heo return; 2740fca839c0STejun Heo 2741fca839c0STejun Heo worker = current_wq_worker(); 2742fca839c0STejun Heo 2743fca839c0STejun Heo WARN_ONCE(current->flags & PF_MEMALLOC, 2744d75f773cSSakari Ailus "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", 2745fca839c0STejun Heo current->pid, current->comm, target_wq->name, target_func); 274623d11a58STejun Heo WARN_ONCE(worker && ((worker->current_pwq->wq->flags & 274723d11a58STejun Heo (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), 2748d75f773cSSakari Ailus "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps", 2749fca839c0STejun Heo worker->current_pwq->wq->name, worker->current_func, 2750fca839c0STejun Heo target_wq->name, target_func); 2751fca839c0STejun Heo } 2752fca839c0STejun Heo 2753fc2e4d70SOleg Nesterov struct wq_barrier { 2754fc2e4d70SOleg Nesterov struct work_struct work; 2755fc2e4d70SOleg Nesterov struct completion done; 27562607d7a6STejun Heo struct task_struct *task; /* purely informational */ 2757fc2e4d70SOleg Nesterov }; 2758fc2e4d70SOleg Nesterov 2759fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2760fc2e4d70SOleg Nesterov { 2761fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2762fc2e4d70SOleg Nesterov complete(&barr->done); 2763fc2e4d70SOleg Nesterov } 2764fc2e4d70SOleg Nesterov 27654690c4abSTejun Heo /** 27664690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 2767112202d9STejun Heo * @pwq: pwq to insert barrier into 27684690c4abSTejun Heo * @barr: wq_barrier to insert 2769affee4b2STejun Heo * @target: target work to attach @barr to 2770affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 27714690c4abSTejun Heo * 2772affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2773affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2774affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2775affee4b2STejun Heo * cpu. 2776affee4b2STejun Heo * 2777affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2778affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2779affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2780affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2781affee4b2STejun Heo * after a work with LINKED flag set. 2782affee4b2STejun Heo * 2783affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2784112202d9STejun Heo * underneath us, so we can't reliably determine pwq from @target. 27854690c4abSTejun Heo * 27864690c4abSTejun Heo * CONTEXT: 2787a9b8a985SSebastian Andrzej Siewior * raw_spin_lock_irq(pool->lock). 27884690c4abSTejun Heo */ 2789112202d9STejun Heo static void insert_wq_barrier(struct pool_workqueue *pwq, 2790affee4b2STejun Heo struct wq_barrier *barr, 2791affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2792fc2e4d70SOleg Nesterov { 2793d812796eSLai Jiangshan unsigned int work_flags = 0; 2794d812796eSLai Jiangshan unsigned int work_color; 2795affee4b2STejun Heo struct list_head *head; 2796affee4b2STejun Heo 2797dc186ad7SThomas Gleixner /* 2798d565ed63STejun Heo * debugobject calls are safe here even with pool->lock locked 2799dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2800dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2801dc186ad7SThomas Gleixner * might deadlock. 2802dc186ad7SThomas Gleixner */ 2803ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 280422df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 280552fa5bc5SBoqun Feng 2806fd1a5b04SByungchul Park init_completion_map(&barr->done, &target->lockdep_map); 2807fd1a5b04SByungchul Park 28082607d7a6STejun Heo barr->task = current; 280983c22520SOleg Nesterov 2810018f3a13SLai Jiangshan /* The barrier work item does not participate in pwq->nr_active. */ 2811018f3a13SLai Jiangshan work_flags |= WORK_STRUCT_INACTIVE; 2812018f3a13SLai Jiangshan 2813affee4b2STejun Heo /* 2814affee4b2STejun Heo * If @target is currently being executed, schedule the 2815affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2816affee4b2STejun Heo */ 2817d812796eSLai Jiangshan if (worker) { 2818affee4b2STejun Heo head = worker->scheduled.next; 2819d812796eSLai Jiangshan work_color = worker->current_color; 2820d812796eSLai Jiangshan } else { 2821affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2822affee4b2STejun Heo 2823affee4b2STejun Heo head = target->entry.next; 2824affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2825d21cece0SLai Jiangshan work_flags |= *bits & WORK_STRUCT_LINKED; 2826d812796eSLai Jiangshan work_color = get_work_color(*bits); 2827affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2828affee4b2STejun Heo } 2829affee4b2STejun Heo 2830d812796eSLai Jiangshan pwq->nr_in_flight[work_color]++; 2831d812796eSLai Jiangshan work_flags |= work_color_to_flags(work_color); 2832d812796eSLai Jiangshan 2833dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2834d21cece0SLai Jiangshan insert_work(pwq, &barr->work, head, work_flags); 2835fc2e4d70SOleg Nesterov } 2836fc2e4d70SOleg Nesterov 283773f53c4aSTejun Heo /** 2838112202d9STejun Heo * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing 283973f53c4aSTejun Heo * @wq: workqueue being flushed 284073f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 284173f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 284273f53c4aSTejun Heo * 2843112202d9STejun Heo * Prepare pwqs for workqueue flushing. 284473f53c4aSTejun Heo * 2845112202d9STejun Heo * If @flush_color is non-negative, flush_color on all pwqs should be 2846112202d9STejun Heo * -1. If no pwq has in-flight commands at the specified color, all 2847112202d9STejun Heo * pwq->flush_color's stay at -1 and %false is returned. If any pwq 2848112202d9STejun Heo * has in flight commands, its pwq->flush_color is set to 2849112202d9STejun Heo * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq 285073f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 285173f53c4aSTejun Heo * 285273f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 285373f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 285473f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 285573f53c4aSTejun Heo * is returned. 285673f53c4aSTejun Heo * 2857112202d9STejun Heo * If @work_color is non-negative, all pwqs should have the same 285873f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 285973f53c4aSTejun Heo * advanced to @work_color. 286073f53c4aSTejun Heo * 286173f53c4aSTejun Heo * CONTEXT: 28623c25a55dSLai Jiangshan * mutex_lock(wq->mutex). 286373f53c4aSTejun Heo * 2864d185af30SYacine Belkadi * Return: 286573f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 286673f53c4aSTejun Heo * otherwise. 286773f53c4aSTejun Heo */ 2868112202d9STejun Heo static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, 286973f53c4aSTejun Heo int flush_color, int work_color) 28701da177e4SLinus Torvalds { 287173f53c4aSTejun Heo bool wait = false; 287249e3cf44STejun Heo struct pool_workqueue *pwq; 28731da177e4SLinus Torvalds 287473f53c4aSTejun Heo if (flush_color >= 0) { 28756183c009STejun Heo WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); 2876112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 1); 2877dc186ad7SThomas Gleixner } 287814441960SOleg Nesterov 287949e3cf44STejun Heo for_each_pwq(pwq, wq) { 2880112202d9STejun Heo struct worker_pool *pool = pwq->pool; 28811da177e4SLinus Torvalds 2882a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 288373f53c4aSTejun Heo 288473f53c4aSTejun Heo if (flush_color >= 0) { 28856183c009STejun Heo WARN_ON_ONCE(pwq->flush_color != -1); 288673f53c4aSTejun Heo 2887112202d9STejun Heo if (pwq->nr_in_flight[flush_color]) { 2888112202d9STejun Heo pwq->flush_color = flush_color; 2889112202d9STejun Heo atomic_inc(&wq->nr_pwqs_to_flush); 289073f53c4aSTejun Heo wait = true; 28911da177e4SLinus Torvalds } 289273f53c4aSTejun Heo } 289373f53c4aSTejun Heo 289473f53c4aSTejun Heo if (work_color >= 0) { 28956183c009STejun Heo WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); 2896112202d9STejun Heo pwq->work_color = work_color; 289773f53c4aSTejun Heo } 289873f53c4aSTejun Heo 2899a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 29001da177e4SLinus Torvalds } 29011da177e4SLinus Torvalds 2902112202d9STejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) 290373f53c4aSTejun Heo complete(&wq->first_flusher->done); 290473f53c4aSTejun Heo 290573f53c4aSTejun Heo return wait; 290683c22520SOleg Nesterov } 29071da177e4SLinus Torvalds 29080fcb78c2SRolf Eike Beer /** 2909c4f135d6STetsuo Handa * __flush_workqueue - ensure that any scheduled work has run to completion. 29100fcb78c2SRolf Eike Beer * @wq: workqueue to flush 29111da177e4SLinus Torvalds * 2912c5aa87bbSTejun Heo * This function sleeps until all work items which were queued on entry 2913c5aa87bbSTejun Heo * have finished execution, but it is not livelocked by new incoming ones. 29141da177e4SLinus Torvalds */ 2915c4f135d6STetsuo Handa void __flush_workqueue(struct workqueue_struct *wq) 29161da177e4SLinus Torvalds { 291773f53c4aSTejun Heo struct wq_flusher this_flusher = { 291873f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 291973f53c4aSTejun Heo .flush_color = -1, 2920fd1a5b04SByungchul Park .done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map), 292173f53c4aSTejun Heo }; 292273f53c4aSTejun Heo int next_color; 2923b1f4ec17SOleg Nesterov 29243347fa09STejun Heo if (WARN_ON(!wq_online)) 29253347fa09STejun Heo return; 29263347fa09STejun Heo 292787915adcSJohannes Berg lock_map_acquire(&wq->lockdep_map); 292887915adcSJohannes Berg lock_map_release(&wq->lockdep_map); 292987915adcSJohannes Berg 29303c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 293173f53c4aSTejun Heo 293273f53c4aSTejun Heo /* 293373f53c4aSTejun Heo * Start-to-wait phase 293473f53c4aSTejun Heo */ 293573f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 293673f53c4aSTejun Heo 293773f53c4aSTejun Heo if (next_color != wq->flush_color) { 293873f53c4aSTejun Heo /* 293973f53c4aSTejun Heo * Color space is not full. The current work_color 294073f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 294173f53c4aSTejun Heo * by one. 294273f53c4aSTejun Heo */ 29436183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); 294473f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 294573f53c4aSTejun Heo wq->work_color = next_color; 294673f53c4aSTejun Heo 294773f53c4aSTejun Heo if (!wq->first_flusher) { 294873f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 29496183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 295073f53c4aSTejun Heo 295173f53c4aSTejun Heo wq->first_flusher = &this_flusher; 295273f53c4aSTejun Heo 2953112202d9STejun Heo if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, 295473f53c4aSTejun Heo wq->work_color)) { 295573f53c4aSTejun Heo /* nothing to flush, done */ 295673f53c4aSTejun Heo wq->flush_color = next_color; 295773f53c4aSTejun Heo wq->first_flusher = NULL; 295873f53c4aSTejun Heo goto out_unlock; 295973f53c4aSTejun Heo } 296073f53c4aSTejun Heo } else { 296173f53c4aSTejun Heo /* wait in queue */ 29626183c009STejun Heo WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); 296373f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 2964112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 296573f53c4aSTejun Heo } 296673f53c4aSTejun Heo } else { 296773f53c4aSTejun Heo /* 296873f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 296973f53c4aSTejun Heo * The next flush completion will assign us 297073f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 297173f53c4aSTejun Heo */ 297273f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 297373f53c4aSTejun Heo } 297473f53c4aSTejun Heo 2975fca839c0STejun Heo check_flush_dependency(wq, NULL); 2976fca839c0STejun Heo 29773c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 297873f53c4aSTejun Heo 297973f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 298073f53c4aSTejun Heo 298173f53c4aSTejun Heo /* 298273f53c4aSTejun Heo * Wake-up-and-cascade phase 298373f53c4aSTejun Heo * 298473f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 298573f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 298673f53c4aSTejun Heo */ 298700d5d15bSChris Wilson if (READ_ONCE(wq->first_flusher) != &this_flusher) 298873f53c4aSTejun Heo return; 298973f53c4aSTejun Heo 29903c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 299173f53c4aSTejun Heo 29924ce48b37STejun Heo /* we might have raced, check again with mutex held */ 29934ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 29944ce48b37STejun Heo goto out_unlock; 29954ce48b37STejun Heo 299600d5d15bSChris Wilson WRITE_ONCE(wq->first_flusher, NULL); 299773f53c4aSTejun Heo 29986183c009STejun Heo WARN_ON_ONCE(!list_empty(&this_flusher.list)); 29996183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 300073f53c4aSTejun Heo 300173f53c4aSTejun Heo while (true) { 300273f53c4aSTejun Heo struct wq_flusher *next, *tmp; 300373f53c4aSTejun Heo 300473f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 300573f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 300673f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 300773f53c4aSTejun Heo break; 300873f53c4aSTejun Heo list_del_init(&next->list); 300973f53c4aSTejun Heo complete(&next->done); 301073f53c4aSTejun Heo } 301173f53c4aSTejun Heo 30126183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && 301373f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 301473f53c4aSTejun Heo 301573f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 301673f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 301773f53c4aSTejun Heo 301873f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 301973f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 302073f53c4aSTejun Heo /* 302173f53c4aSTejun Heo * Assign the same color to all overflowed 302273f53c4aSTejun Heo * flushers, advance work_color and append to 302373f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 302473f53c4aSTejun Heo * phase for these overflowed flushers. 302573f53c4aSTejun Heo */ 302673f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 302773f53c4aSTejun Heo tmp->flush_color = wq->work_color; 302873f53c4aSTejun Heo 302973f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 303073f53c4aSTejun Heo 303173f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 303273f53c4aSTejun Heo &wq->flusher_queue); 3033112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 303473f53c4aSTejun Heo } 303573f53c4aSTejun Heo 303673f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 30376183c009STejun Heo WARN_ON_ONCE(wq->flush_color != wq->work_color); 303873f53c4aSTejun Heo break; 303973f53c4aSTejun Heo } 304073f53c4aSTejun Heo 304173f53c4aSTejun Heo /* 304273f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 3043112202d9STejun Heo * the new first flusher and arm pwqs. 304473f53c4aSTejun Heo */ 30456183c009STejun Heo WARN_ON_ONCE(wq->flush_color == wq->work_color); 30466183c009STejun Heo WARN_ON_ONCE(wq->flush_color != next->flush_color); 304773f53c4aSTejun Heo 304873f53c4aSTejun Heo list_del_init(&next->list); 304973f53c4aSTejun Heo wq->first_flusher = next; 305073f53c4aSTejun Heo 3051112202d9STejun Heo if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) 305273f53c4aSTejun Heo break; 305373f53c4aSTejun Heo 305473f53c4aSTejun Heo /* 305573f53c4aSTejun Heo * Meh... this color is already done, clear first 305673f53c4aSTejun Heo * flusher and repeat cascading. 305773f53c4aSTejun Heo */ 305873f53c4aSTejun Heo wq->first_flusher = NULL; 305973f53c4aSTejun Heo } 306073f53c4aSTejun Heo 306173f53c4aSTejun Heo out_unlock: 30623c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 30631da177e4SLinus Torvalds } 3064c4f135d6STetsuo Handa EXPORT_SYMBOL(__flush_workqueue); 30651da177e4SLinus Torvalds 30669c5a2ba7STejun Heo /** 30679c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 30689c5a2ba7STejun Heo * @wq: workqueue to drain 30699c5a2ba7STejun Heo * 30709c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 30719c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 30729c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 3073b749b1b6SChen Hanxiao * repeatedly until it becomes empty. The number of flushing is determined 30749c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 30759c5a2ba7STejun Heo * takes too long. 30769c5a2ba7STejun Heo */ 30779c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 30789c5a2ba7STejun Heo { 30799c5a2ba7STejun Heo unsigned int flush_cnt = 0; 308049e3cf44STejun Heo struct pool_workqueue *pwq; 30819c5a2ba7STejun Heo 30829c5a2ba7STejun Heo /* 30839c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 30849c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 3085618b01ebSTejun Heo * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. 30869c5a2ba7STejun Heo */ 308787fc741eSLai Jiangshan mutex_lock(&wq->mutex); 30889c5a2ba7STejun Heo if (!wq->nr_drainers++) 3089618b01ebSTejun Heo wq->flags |= __WQ_DRAINING; 309087fc741eSLai Jiangshan mutex_unlock(&wq->mutex); 30919c5a2ba7STejun Heo reflush: 3092c4f135d6STetsuo Handa __flush_workqueue(wq); 30939c5a2ba7STejun Heo 3094b09f4fd3SLai Jiangshan mutex_lock(&wq->mutex); 309576af4d93STejun Heo 309649e3cf44STejun Heo for_each_pwq(pwq, wq) { 3097fa2563e4SThomas Tuttle bool drained; 30989c5a2ba7STejun Heo 3099a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pwq->pool->lock); 3100f97a4a1aSLai Jiangshan drained = !pwq->nr_active && list_empty(&pwq->inactive_works); 3101a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pwq->pool->lock); 3102fa2563e4SThomas Tuttle 3103fa2563e4SThomas Tuttle if (drained) 31049c5a2ba7STejun Heo continue; 31059c5a2ba7STejun Heo 31069c5a2ba7STejun Heo if (++flush_cnt == 10 || 31079c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 3108e9ad2eb3SStephen Zhang pr_warn("workqueue %s: %s() isn't complete after %u tries\n", 3109e9ad2eb3SStephen Zhang wq->name, __func__, flush_cnt); 311076af4d93STejun Heo 3111b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 31129c5a2ba7STejun Heo goto reflush; 31139c5a2ba7STejun Heo } 31149c5a2ba7STejun Heo 31159c5a2ba7STejun Heo if (!--wq->nr_drainers) 3116618b01ebSTejun Heo wq->flags &= ~__WQ_DRAINING; 311787fc741eSLai Jiangshan mutex_unlock(&wq->mutex); 31189c5a2ba7STejun Heo } 31199c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 31209c5a2ba7STejun Heo 3121d6e89786SJohannes Berg static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, 3122d6e89786SJohannes Berg bool from_cancel) 3123baf59022STejun Heo { 3124baf59022STejun Heo struct worker *worker = NULL; 3125c9e7cf27STejun Heo struct worker_pool *pool; 3126112202d9STejun Heo struct pool_workqueue *pwq; 3127baf59022STejun Heo 3128baf59022STejun Heo might_sleep(); 3129baf59022STejun Heo 313024acfb71SThomas Gleixner rcu_read_lock(); 3131fa1b54e6STejun Heo pool = get_work_pool(work); 3132fa1b54e6STejun Heo if (!pool) { 313324acfb71SThomas Gleixner rcu_read_unlock(); 3134fa1b54e6STejun Heo return false; 3135fa1b54e6STejun Heo } 3136fa1b54e6STejun Heo 3137a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 31380b3dae68SLai Jiangshan /* see the comment in try_to_grab_pending() with the same code */ 3139112202d9STejun Heo pwq = get_work_pwq(work); 3140112202d9STejun Heo if (pwq) { 3141112202d9STejun Heo if (unlikely(pwq->pool != pool)) 3142baf59022STejun Heo goto already_gone; 3143606a5020STejun Heo } else { 3144c9e7cf27STejun Heo worker = find_worker_executing_work(pool, work); 3145baf59022STejun Heo if (!worker) 3146baf59022STejun Heo goto already_gone; 3147112202d9STejun Heo pwq = worker->current_pwq; 3148606a5020STejun Heo } 3149baf59022STejun Heo 3150fca839c0STejun Heo check_flush_dependency(pwq->wq, work); 3151fca839c0STejun Heo 3152112202d9STejun Heo insert_wq_barrier(pwq, barr, work, worker); 3153a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 3154baf59022STejun Heo 3155e159489bSTejun Heo /* 3156a1d14934SPeter Zijlstra * Force a lock recursion deadlock when using flush_work() inside a 3157a1d14934SPeter Zijlstra * single-threaded or rescuer equipped workqueue. 3158a1d14934SPeter Zijlstra * 3159a1d14934SPeter Zijlstra * For single threaded workqueues the deadlock happens when the work 3160a1d14934SPeter Zijlstra * is after the work issuing the flush_work(). For rescuer equipped 3161a1d14934SPeter Zijlstra * workqueues the deadlock happens when the rescuer stalls, blocking 3162a1d14934SPeter Zijlstra * forward progress. 3163e159489bSTejun Heo */ 3164d6e89786SJohannes Berg if (!from_cancel && 3165d6e89786SJohannes Berg (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)) { 3166112202d9STejun Heo lock_map_acquire(&pwq->wq->lockdep_map); 3167112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 3168a1d14934SPeter Zijlstra } 316924acfb71SThomas Gleixner rcu_read_unlock(); 3170baf59022STejun Heo return true; 3171baf59022STejun Heo already_gone: 3172a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 317324acfb71SThomas Gleixner rcu_read_unlock(); 3174baf59022STejun Heo return false; 3175baf59022STejun Heo } 3176baf59022STejun Heo 3177d6e89786SJohannes Berg static bool __flush_work(struct work_struct *work, bool from_cancel) 3178d6e89786SJohannes Berg { 3179d6e89786SJohannes Berg struct wq_barrier barr; 3180d6e89786SJohannes Berg 3181d6e89786SJohannes Berg if (WARN_ON(!wq_online)) 3182d6e89786SJohannes Berg return false; 3183d6e89786SJohannes Berg 31844d43d395STetsuo Handa if (WARN_ON(!work->func)) 31854d43d395STetsuo Handa return false; 31864d43d395STetsuo Handa 318787915adcSJohannes Berg lock_map_acquire(&work->lockdep_map); 318887915adcSJohannes Berg lock_map_release(&work->lockdep_map); 318987915adcSJohannes Berg 3190d6e89786SJohannes Berg if (start_flush_work(work, &barr, from_cancel)) { 3191d6e89786SJohannes Berg wait_for_completion(&barr.done); 3192d6e89786SJohannes Berg destroy_work_on_stack(&barr.work); 3193d6e89786SJohannes Berg return true; 3194d6e89786SJohannes Berg } else { 3195d6e89786SJohannes Berg return false; 3196d6e89786SJohannes Berg } 3197d6e89786SJohannes Berg } 3198d6e89786SJohannes Berg 3199db700897SOleg Nesterov /** 3200401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 3201401a8d04STejun Heo * @work: the work to flush 3202db700897SOleg Nesterov * 3203606a5020STejun Heo * Wait until @work has finished execution. @work is guaranteed to be idle 3204606a5020STejun Heo * on return if it hasn't been requeued since flush started. 3205401a8d04STejun Heo * 3206d185af30SYacine Belkadi * Return: 3207401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 3208401a8d04STejun Heo * %false if it was already idle. 3209db700897SOleg Nesterov */ 3210401a8d04STejun Heo bool flush_work(struct work_struct *work) 3211db700897SOleg Nesterov { 3212d6e89786SJohannes Berg return __flush_work(work, false); 3213606a5020STejun Heo } 3214db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 3215db700897SOleg Nesterov 32168603e1b3STejun Heo struct cwt_wait { 3217ac6424b9SIngo Molnar wait_queue_entry_t wait; 32188603e1b3STejun Heo struct work_struct *work; 32198603e1b3STejun Heo }; 32208603e1b3STejun Heo 3221ac6424b9SIngo Molnar static int cwt_wakefn(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) 32228603e1b3STejun Heo { 32238603e1b3STejun Heo struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait); 32248603e1b3STejun Heo 32258603e1b3STejun Heo if (cwait->work != key) 32268603e1b3STejun Heo return 0; 32278603e1b3STejun Heo return autoremove_wake_function(wait, mode, sync, key); 32288603e1b3STejun Heo } 32298603e1b3STejun Heo 323036e227d2STejun Heo static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 3231401a8d04STejun Heo { 32328603e1b3STejun Heo static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq); 3233bbb68dfaSTejun Heo unsigned long flags; 32341f1f642eSOleg Nesterov int ret; 32351f1f642eSOleg Nesterov 32361f1f642eSOleg Nesterov do { 3237bbb68dfaSTejun Heo ret = try_to_grab_pending(work, is_dwork, &flags); 3238bbb68dfaSTejun Heo /* 32398603e1b3STejun Heo * If someone else is already canceling, wait for it to 32408603e1b3STejun Heo * finish. flush_work() doesn't work for PREEMPT_NONE 32418603e1b3STejun Heo * because we may get scheduled between @work's completion 32428603e1b3STejun Heo * and the other canceling task resuming and clearing 32438603e1b3STejun Heo * CANCELING - flush_work() will return false immediately 32448603e1b3STejun Heo * as @work is no longer busy, try_to_grab_pending() will 32458603e1b3STejun Heo * return -ENOENT as @work is still being canceled and the 32468603e1b3STejun Heo * other canceling task won't be able to clear CANCELING as 32478603e1b3STejun Heo * we're hogging the CPU. 32488603e1b3STejun Heo * 32498603e1b3STejun Heo * Let's wait for completion using a waitqueue. As this 32508603e1b3STejun Heo * may lead to the thundering herd problem, use a custom 32518603e1b3STejun Heo * wake function which matches @work along with exclusive 32528603e1b3STejun Heo * wait and wakeup. 3253bbb68dfaSTejun Heo */ 32548603e1b3STejun Heo if (unlikely(ret == -ENOENT)) { 32558603e1b3STejun Heo struct cwt_wait cwait; 32568603e1b3STejun Heo 32578603e1b3STejun Heo init_wait(&cwait.wait); 32588603e1b3STejun Heo cwait.wait.func = cwt_wakefn; 32598603e1b3STejun Heo cwait.work = work; 32608603e1b3STejun Heo 32618603e1b3STejun Heo prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait, 32628603e1b3STejun Heo TASK_UNINTERRUPTIBLE); 32638603e1b3STejun Heo if (work_is_canceling(work)) 32648603e1b3STejun Heo schedule(); 32658603e1b3STejun Heo finish_wait(&cancel_waitq, &cwait.wait); 32668603e1b3STejun Heo } 32671f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 32681f1f642eSOleg Nesterov 3269bbb68dfaSTejun Heo /* tell other tasks trying to grab @work to back off */ 3270bbb68dfaSTejun Heo mark_work_canceling(work); 3271bbb68dfaSTejun Heo local_irq_restore(flags); 3272bbb68dfaSTejun Heo 32733347fa09STejun Heo /* 32743347fa09STejun Heo * This allows canceling during early boot. We know that @work 32753347fa09STejun Heo * isn't executing. 32763347fa09STejun Heo */ 32773347fa09STejun Heo if (wq_online) 3278d6e89786SJohannes Berg __flush_work(work, true); 32793347fa09STejun Heo 32807a22ad75STejun Heo clear_work_data(work); 32818603e1b3STejun Heo 32828603e1b3STejun Heo /* 32838603e1b3STejun Heo * Paired with prepare_to_wait() above so that either 32848603e1b3STejun Heo * waitqueue_active() is visible here or !work_is_canceling() is 32858603e1b3STejun Heo * visible there. 32868603e1b3STejun Heo */ 32878603e1b3STejun Heo smp_mb(); 32888603e1b3STejun Heo if (waitqueue_active(&cancel_waitq)) 32898603e1b3STejun Heo __wake_up(&cancel_waitq, TASK_NORMAL, 1, work); 32908603e1b3STejun Heo 32911f1f642eSOleg Nesterov return ret; 32921f1f642eSOleg Nesterov } 32931f1f642eSOleg Nesterov 32946e84d644SOleg Nesterov /** 3295401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 3296401a8d04STejun Heo * @work: the work to cancel 32976e84d644SOleg Nesterov * 3298401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 3299401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 3300401a8d04STejun Heo * another workqueue. On return from this function, @work is 3301401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 33021f1f642eSOleg Nesterov * 3303401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 3304401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 33056e84d644SOleg Nesterov * 3306401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 33076e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 3308401a8d04STejun Heo * 3309d185af30SYacine Belkadi * Return: 3310401a8d04STejun Heo * %true if @work was pending, %false otherwise. 33116e84d644SOleg Nesterov */ 3312401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 33136e84d644SOleg Nesterov { 331436e227d2STejun Heo return __cancel_work_timer(work, false); 3315b89deed3SOleg Nesterov } 331628e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 3317b89deed3SOleg Nesterov 33186e84d644SOleg Nesterov /** 3319401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 3320401a8d04STejun Heo * @dwork: the delayed work to flush 33216e84d644SOleg Nesterov * 3322401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 3323401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 3324401a8d04STejun Heo * considers the last queueing instance of @dwork. 33251f1f642eSOleg Nesterov * 3326d185af30SYacine Belkadi * Return: 3327401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 3328401a8d04STejun Heo * %false if it was already idle. 33296e84d644SOleg Nesterov */ 3330401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 3331401a8d04STejun Heo { 33328930cabaSTejun Heo local_irq_disable(); 3333401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 333460c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 33358930cabaSTejun Heo local_irq_enable(); 3336401a8d04STejun Heo return flush_work(&dwork->work); 3337401a8d04STejun Heo } 3338401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 3339401a8d04STejun Heo 334005f0fe6bSTejun Heo /** 334105f0fe6bSTejun Heo * flush_rcu_work - wait for a rwork to finish executing the last queueing 334205f0fe6bSTejun Heo * @rwork: the rcu work to flush 334305f0fe6bSTejun Heo * 334405f0fe6bSTejun Heo * Return: 334505f0fe6bSTejun Heo * %true if flush_rcu_work() waited for the work to finish execution, 334605f0fe6bSTejun Heo * %false if it was already idle. 334705f0fe6bSTejun Heo */ 334805f0fe6bSTejun Heo bool flush_rcu_work(struct rcu_work *rwork) 334905f0fe6bSTejun Heo { 335005f0fe6bSTejun Heo if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) { 335105f0fe6bSTejun Heo rcu_barrier(); 335205f0fe6bSTejun Heo flush_work(&rwork->work); 335305f0fe6bSTejun Heo return true; 335405f0fe6bSTejun Heo } else { 335505f0fe6bSTejun Heo return flush_work(&rwork->work); 335605f0fe6bSTejun Heo } 335705f0fe6bSTejun Heo } 335805f0fe6bSTejun Heo EXPORT_SYMBOL(flush_rcu_work); 335905f0fe6bSTejun Heo 3360f72b8792SJens Axboe static bool __cancel_work(struct work_struct *work, bool is_dwork) 3361f72b8792SJens Axboe { 3362f72b8792SJens Axboe unsigned long flags; 3363f72b8792SJens Axboe int ret; 3364f72b8792SJens Axboe 3365f72b8792SJens Axboe do { 3366f72b8792SJens Axboe ret = try_to_grab_pending(work, is_dwork, &flags); 3367f72b8792SJens Axboe } while (unlikely(ret == -EAGAIN)); 3368f72b8792SJens Axboe 3369f72b8792SJens Axboe if (unlikely(ret < 0)) 3370f72b8792SJens Axboe return false; 3371f72b8792SJens Axboe 3372f72b8792SJens Axboe set_work_pool_and_clear_pending(work, get_work_pool_id(work)); 3373f72b8792SJens Axboe local_irq_restore(flags); 3374f72b8792SJens Axboe return ret; 3375f72b8792SJens Axboe } 3376f72b8792SJens Axboe 337773b4b532SAndrey Grodzovsky /* 337873b4b532SAndrey Grodzovsky * See cancel_delayed_work() 337973b4b532SAndrey Grodzovsky */ 338073b4b532SAndrey Grodzovsky bool cancel_work(struct work_struct *work) 338173b4b532SAndrey Grodzovsky { 338273b4b532SAndrey Grodzovsky return __cancel_work(work, false); 338373b4b532SAndrey Grodzovsky } 338473b4b532SAndrey Grodzovsky EXPORT_SYMBOL(cancel_work); 338573b4b532SAndrey Grodzovsky 3386401a8d04STejun Heo /** 338757b30ae7STejun Heo * cancel_delayed_work - cancel a delayed work 338857b30ae7STejun Heo * @dwork: delayed_work to cancel 338909383498STejun Heo * 3390d185af30SYacine Belkadi * Kill off a pending delayed_work. 3391d185af30SYacine Belkadi * 3392d185af30SYacine Belkadi * Return: %true if @dwork was pending and canceled; %false if it wasn't 3393d185af30SYacine Belkadi * pending. 3394d185af30SYacine Belkadi * 3395d185af30SYacine Belkadi * Note: 3396d185af30SYacine Belkadi * The work callback function may still be running on return, unless 3397d185af30SYacine Belkadi * it returns %true and the work doesn't re-arm itself. Explicitly flush or 3398d185af30SYacine Belkadi * use cancel_delayed_work_sync() to wait on it. 339909383498STejun Heo * 340057b30ae7STejun Heo * This function is safe to call from any context including IRQ handler. 340109383498STejun Heo */ 340257b30ae7STejun Heo bool cancel_delayed_work(struct delayed_work *dwork) 340309383498STejun Heo { 3404f72b8792SJens Axboe return __cancel_work(&dwork->work, true); 340509383498STejun Heo } 340657b30ae7STejun Heo EXPORT_SYMBOL(cancel_delayed_work); 340709383498STejun Heo 340809383498STejun Heo /** 3409401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 3410401a8d04STejun Heo * @dwork: the delayed work cancel 3411401a8d04STejun Heo * 3412401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 3413401a8d04STejun Heo * 3414d185af30SYacine Belkadi * Return: 3415401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 3416401a8d04STejun Heo */ 3417401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 34186e84d644SOleg Nesterov { 341936e227d2STejun Heo return __cancel_work_timer(&dwork->work, true); 34206e84d644SOleg Nesterov } 3421f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 34221da177e4SLinus Torvalds 34230fcb78c2SRolf Eike Beer /** 342431ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 3425b6136773SAndrew Morton * @func: the function to call 3426b6136773SAndrew Morton * 342731ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 342831ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 3429b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 343031ddd871STejun Heo * 3431d185af30SYacine Belkadi * Return: 343231ddd871STejun Heo * 0 on success, -errno on failure. 3433b6136773SAndrew Morton */ 343465f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 343515316ba8SChristoph Lameter { 343615316ba8SChristoph Lameter int cpu; 343738f51568SNamhyung Kim struct work_struct __percpu *works; 343815316ba8SChristoph Lameter 3439b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 3440b6136773SAndrew Morton if (!works) 344115316ba8SChristoph Lameter return -ENOMEM; 3442b6136773SAndrew Morton 3443ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 344493981800STejun Heo 344515316ba8SChristoph Lameter for_each_online_cpu(cpu) { 34469bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 34479bfb1839SIngo Molnar 34489bfb1839SIngo Molnar INIT_WORK(work, func); 34498de6d308SOleg Nesterov schedule_work_on(cpu, work); 345015316ba8SChristoph Lameter } 345193981800STejun Heo 345293981800STejun Heo for_each_online_cpu(cpu) 34538616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 345493981800STejun Heo 3455ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 3456b6136773SAndrew Morton free_percpu(works); 345715316ba8SChristoph Lameter return 0; 345815316ba8SChristoph Lameter } 345915316ba8SChristoph Lameter 3460eef6a7d5SAlan Stern /** 34611fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 34621fa44ecaSJames Bottomley * @fn: the function to execute 34631fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 34641fa44ecaSJames Bottomley * be available when the work executes) 34651fa44ecaSJames Bottomley * 34661fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 34671fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 34681fa44ecaSJames Bottomley * 3469d185af30SYacine Belkadi * Return: 0 - function was executed 34701fa44ecaSJames Bottomley * 1 - function was scheduled for execution 34711fa44ecaSJames Bottomley */ 347265f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 34731fa44ecaSJames Bottomley { 34741fa44ecaSJames Bottomley if (!in_interrupt()) { 347565f27f38SDavid Howells fn(&ew->work); 34761fa44ecaSJames Bottomley return 0; 34771fa44ecaSJames Bottomley } 34781fa44ecaSJames Bottomley 347965f27f38SDavid Howells INIT_WORK(&ew->work, fn); 34801fa44ecaSJames Bottomley schedule_work(&ew->work); 34811fa44ecaSJames Bottomley 34821fa44ecaSJames Bottomley return 1; 34831fa44ecaSJames Bottomley } 34841fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 34851fa44ecaSJames Bottomley 34867a4e344cSTejun Heo /** 34877a4e344cSTejun Heo * free_workqueue_attrs - free a workqueue_attrs 34887a4e344cSTejun Heo * @attrs: workqueue_attrs to free 34897a4e344cSTejun Heo * 34907a4e344cSTejun Heo * Undo alloc_workqueue_attrs(). 34917a4e344cSTejun Heo */ 3492513c98d0SDaniel Jordan void free_workqueue_attrs(struct workqueue_attrs *attrs) 34937a4e344cSTejun Heo { 34947a4e344cSTejun Heo if (attrs) { 34957a4e344cSTejun Heo free_cpumask_var(attrs->cpumask); 34967a4e344cSTejun Heo kfree(attrs); 34977a4e344cSTejun Heo } 34987a4e344cSTejun Heo } 34997a4e344cSTejun Heo 35007a4e344cSTejun Heo /** 35017a4e344cSTejun Heo * alloc_workqueue_attrs - allocate a workqueue_attrs 35027a4e344cSTejun Heo * 35037a4e344cSTejun Heo * Allocate a new workqueue_attrs, initialize with default settings and 3504d185af30SYacine Belkadi * return it. 3505d185af30SYacine Belkadi * 3506d185af30SYacine Belkadi * Return: The allocated new workqueue_attr on success. %NULL on failure. 35077a4e344cSTejun Heo */ 3508513c98d0SDaniel Jordan struct workqueue_attrs *alloc_workqueue_attrs(void) 35097a4e344cSTejun Heo { 35107a4e344cSTejun Heo struct workqueue_attrs *attrs; 35117a4e344cSTejun Heo 3512be69d00dSThomas Gleixner attrs = kzalloc(sizeof(*attrs), GFP_KERNEL); 35137a4e344cSTejun Heo if (!attrs) 35147a4e344cSTejun Heo goto fail; 3515be69d00dSThomas Gleixner if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL)) 35167a4e344cSTejun Heo goto fail; 35177a4e344cSTejun Heo 351813e2e556STejun Heo cpumask_copy(attrs->cpumask, cpu_possible_mask); 35197a4e344cSTejun Heo return attrs; 35207a4e344cSTejun Heo fail: 35217a4e344cSTejun Heo free_workqueue_attrs(attrs); 35227a4e344cSTejun Heo return NULL; 35237a4e344cSTejun Heo } 35247a4e344cSTejun Heo 352529c91e99STejun Heo static void copy_workqueue_attrs(struct workqueue_attrs *to, 352629c91e99STejun Heo const struct workqueue_attrs *from) 352729c91e99STejun Heo { 352829c91e99STejun Heo to->nice = from->nice; 352929c91e99STejun Heo cpumask_copy(to->cpumask, from->cpumask); 35302865a8fbSShaohua Li /* 35312865a8fbSShaohua Li * Unlike hash and equality test, this function doesn't ignore 35322865a8fbSShaohua Li * ->no_numa as it is used for both pool and wq attrs. Instead, 35332865a8fbSShaohua Li * get_unbound_pool() explicitly clears ->no_numa after copying. 35342865a8fbSShaohua Li */ 35352865a8fbSShaohua Li to->no_numa = from->no_numa; 353629c91e99STejun Heo } 353729c91e99STejun Heo 353829c91e99STejun Heo /* hash value of the content of @attr */ 353929c91e99STejun Heo static u32 wqattrs_hash(const struct workqueue_attrs *attrs) 354029c91e99STejun Heo { 354129c91e99STejun Heo u32 hash = 0; 354229c91e99STejun Heo 354329c91e99STejun Heo hash = jhash_1word(attrs->nice, hash); 354413e2e556STejun Heo hash = jhash(cpumask_bits(attrs->cpumask), 354513e2e556STejun Heo BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); 354629c91e99STejun Heo return hash; 354729c91e99STejun Heo } 354829c91e99STejun Heo 354929c91e99STejun Heo /* content equality test */ 355029c91e99STejun Heo static bool wqattrs_equal(const struct workqueue_attrs *a, 355129c91e99STejun Heo const struct workqueue_attrs *b) 355229c91e99STejun Heo { 355329c91e99STejun Heo if (a->nice != b->nice) 355429c91e99STejun Heo return false; 355529c91e99STejun Heo if (!cpumask_equal(a->cpumask, b->cpumask)) 355629c91e99STejun Heo return false; 355729c91e99STejun Heo return true; 355829c91e99STejun Heo } 355929c91e99STejun Heo 35607a4e344cSTejun Heo /** 35617a4e344cSTejun Heo * init_worker_pool - initialize a newly zalloc'd worker_pool 35627a4e344cSTejun Heo * @pool: worker_pool to initialize 35637a4e344cSTejun Heo * 3564402dd89dSShailendra Verma * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. 3565d185af30SYacine Belkadi * 3566d185af30SYacine Belkadi * Return: 0 on success, -errno on failure. Even on failure, all fields 356729c91e99STejun Heo * inside @pool proper are initialized and put_unbound_pool() can be called 356829c91e99STejun Heo * on @pool safely to release it. 35697a4e344cSTejun Heo */ 35707a4e344cSTejun Heo static int init_worker_pool(struct worker_pool *pool) 35714e1a1f9aSTejun Heo { 3572a9b8a985SSebastian Andrzej Siewior raw_spin_lock_init(&pool->lock); 357329c91e99STejun Heo pool->id = -1; 357429c91e99STejun Heo pool->cpu = -1; 3575f3f90ad4STejun Heo pool->node = NUMA_NO_NODE; 35764e1a1f9aSTejun Heo pool->flags |= POOL_DISASSOCIATED; 357782607adcSTejun Heo pool->watchdog_ts = jiffies; 35784e1a1f9aSTejun Heo INIT_LIST_HEAD(&pool->worklist); 35794e1a1f9aSTejun Heo INIT_LIST_HEAD(&pool->idle_list); 35804e1a1f9aSTejun Heo hash_init(pool->busy_hash); 35814e1a1f9aSTejun Heo 358232a6c723SKees Cook timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE); 35833f959aa3SValentin Schneider INIT_WORK(&pool->idle_cull_work, idle_cull_fn); 35844e1a1f9aSTejun Heo 358532a6c723SKees Cook timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0); 35864e1a1f9aSTejun Heo 3587da028469SLai Jiangshan INIT_LIST_HEAD(&pool->workers); 3588e02b9312SValentin Schneider INIT_LIST_HEAD(&pool->dying_workers); 35897a4e344cSTejun Heo 35907cda9aaeSLai Jiangshan ida_init(&pool->worker_ida); 359129c91e99STejun Heo INIT_HLIST_NODE(&pool->hash_node); 359229c91e99STejun Heo pool->refcnt = 1; 359329c91e99STejun Heo 359429c91e99STejun Heo /* shouldn't fail above this point */ 3595be69d00dSThomas Gleixner pool->attrs = alloc_workqueue_attrs(); 35967a4e344cSTejun Heo if (!pool->attrs) 35977a4e344cSTejun Heo return -ENOMEM; 35987a4e344cSTejun Heo return 0; 35994e1a1f9aSTejun Heo } 36004e1a1f9aSTejun Heo 3601669de8bdSBart Van Assche #ifdef CONFIG_LOCKDEP 3602669de8bdSBart Van Assche static void wq_init_lockdep(struct workqueue_struct *wq) 3603669de8bdSBart Van Assche { 3604669de8bdSBart Van Assche char *lock_name; 3605669de8bdSBart Van Assche 3606669de8bdSBart Van Assche lockdep_register_key(&wq->key); 3607669de8bdSBart Van Assche lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name); 3608669de8bdSBart Van Assche if (!lock_name) 3609669de8bdSBart Van Assche lock_name = wq->name; 361069a106c0SQian Cai 361169a106c0SQian Cai wq->lock_name = lock_name; 3612669de8bdSBart Van Assche lockdep_init_map(&wq->lockdep_map, lock_name, &wq->key, 0); 3613669de8bdSBart Van Assche } 3614669de8bdSBart Van Assche 3615669de8bdSBart Van Assche static void wq_unregister_lockdep(struct workqueue_struct *wq) 3616669de8bdSBart Van Assche { 3617669de8bdSBart Van Assche lockdep_unregister_key(&wq->key); 3618669de8bdSBart Van Assche } 3619669de8bdSBart Van Assche 3620669de8bdSBart Van Assche static void wq_free_lockdep(struct workqueue_struct *wq) 3621669de8bdSBart Van Assche { 3622669de8bdSBart Van Assche if (wq->lock_name != wq->name) 3623669de8bdSBart Van Assche kfree(wq->lock_name); 3624669de8bdSBart Van Assche } 3625669de8bdSBart Van Assche #else 3626669de8bdSBart Van Assche static void wq_init_lockdep(struct workqueue_struct *wq) 3627669de8bdSBart Van Assche { 3628669de8bdSBart Van Assche } 3629669de8bdSBart Van Assche 3630669de8bdSBart Van Assche static void wq_unregister_lockdep(struct workqueue_struct *wq) 3631669de8bdSBart Van Assche { 3632669de8bdSBart Van Assche } 3633669de8bdSBart Van Assche 3634669de8bdSBart Van Assche static void wq_free_lockdep(struct workqueue_struct *wq) 3635669de8bdSBart Van Assche { 3636669de8bdSBart Van Assche } 3637669de8bdSBart Van Assche #endif 3638669de8bdSBart Van Assche 3639e2dca7adSTejun Heo static void rcu_free_wq(struct rcu_head *rcu) 3640e2dca7adSTejun Heo { 3641e2dca7adSTejun Heo struct workqueue_struct *wq = 3642e2dca7adSTejun Heo container_of(rcu, struct workqueue_struct, rcu); 3643e2dca7adSTejun Heo 3644669de8bdSBart Van Assche wq_free_lockdep(wq); 3645669de8bdSBart Van Assche 3646e2dca7adSTejun Heo if (!(wq->flags & WQ_UNBOUND)) 3647e2dca7adSTejun Heo free_percpu(wq->cpu_pwqs); 3648e2dca7adSTejun Heo else 3649e2dca7adSTejun Heo free_workqueue_attrs(wq->unbound_attrs); 3650e2dca7adSTejun Heo 3651e2dca7adSTejun Heo kfree(wq); 3652e2dca7adSTejun Heo } 3653e2dca7adSTejun Heo 365429c91e99STejun Heo static void rcu_free_pool(struct rcu_head *rcu) 365529c91e99STejun Heo { 365629c91e99STejun Heo struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); 365729c91e99STejun Heo 36587cda9aaeSLai Jiangshan ida_destroy(&pool->worker_ida); 365929c91e99STejun Heo free_workqueue_attrs(pool->attrs); 366029c91e99STejun Heo kfree(pool); 366129c91e99STejun Heo } 366229c91e99STejun Heo 366329c91e99STejun Heo /** 366429c91e99STejun Heo * put_unbound_pool - put a worker_pool 366529c91e99STejun Heo * @pool: worker_pool to put 366629c91e99STejun Heo * 366724acfb71SThomas Gleixner * Put @pool. If its refcnt reaches zero, it gets destroyed in RCU 3668c5aa87bbSTejun Heo * safe manner. get_unbound_pool() calls this function on its failure path 3669c5aa87bbSTejun Heo * and this function should be able to release pools which went through, 3670c5aa87bbSTejun Heo * successfully or not, init_worker_pool(). 3671a892caccSTejun Heo * 3672a892caccSTejun Heo * Should be called with wq_pool_mutex held. 367329c91e99STejun Heo */ 367429c91e99STejun Heo static void put_unbound_pool(struct worker_pool *pool) 367529c91e99STejun Heo { 367660f5a4bcSLai Jiangshan DECLARE_COMPLETION_ONSTACK(detach_completion); 3677e02b9312SValentin Schneider struct list_head cull_list; 367829c91e99STejun Heo struct worker *worker; 367929c91e99STejun Heo 3680e02b9312SValentin Schneider INIT_LIST_HEAD(&cull_list); 3681e02b9312SValentin Schneider 3682a892caccSTejun Heo lockdep_assert_held(&wq_pool_mutex); 3683a892caccSTejun Heo 3684a892caccSTejun Heo if (--pool->refcnt) 368529c91e99STejun Heo return; 368629c91e99STejun Heo 368729c91e99STejun Heo /* sanity checks */ 368861d0fbb4SLai Jiangshan if (WARN_ON(!(pool->cpu < 0)) || 3689a892caccSTejun Heo WARN_ON(!list_empty(&pool->worklist))) 369029c91e99STejun Heo return; 369129c91e99STejun Heo 369229c91e99STejun Heo /* release id and unhash */ 369329c91e99STejun Heo if (pool->id >= 0) 369429c91e99STejun Heo idr_remove(&worker_pool_idr, pool->id); 369529c91e99STejun Heo hash_del(&pool->hash_node); 369629c91e99STejun Heo 3697c5aa87bbSTejun Heo /* 3698692b4825STejun Heo * Become the manager and destroy all workers. This prevents 3699692b4825STejun Heo * @pool's workers from blocking on attach_mutex. We're the last 3700692b4825STejun Heo * manager and @pool gets freed with the flag set. 37019ab03be4SValentin Schneider * 37029ab03be4SValentin Schneider * Having a concurrent manager is quite unlikely to happen as we can 37039ab03be4SValentin Schneider * only get here with 37049ab03be4SValentin Schneider * pwq->refcnt == pool->refcnt == 0 37059ab03be4SValentin Schneider * which implies no work queued to the pool, which implies no worker can 37069ab03be4SValentin Schneider * become the manager. However a worker could have taken the role of 37079ab03be4SValentin Schneider * manager before the refcnts dropped to 0, since maybe_create_worker() 37089ab03be4SValentin Schneider * drops pool->lock 3709c5aa87bbSTejun Heo */ 37109ab03be4SValentin Schneider while (true) { 37119ab03be4SValentin Schneider rcuwait_wait_event(&manager_wait, 37129ab03be4SValentin Schneider !(pool->flags & POOL_MANAGER_ACTIVE), 3713d8bb65abSSebastian Andrzej Siewior TASK_UNINTERRUPTIBLE); 3714e02b9312SValentin Schneider 3715e02b9312SValentin Schneider mutex_lock(&wq_pool_attach_mutex); 37169ab03be4SValentin Schneider raw_spin_lock_irq(&pool->lock); 37179ab03be4SValentin Schneider if (!(pool->flags & POOL_MANAGER_ACTIVE)) { 3718692b4825STejun Heo pool->flags |= POOL_MANAGER_ACTIVE; 37199ab03be4SValentin Schneider break; 37209ab03be4SValentin Schneider } 37219ab03be4SValentin Schneider raw_spin_unlock_irq(&pool->lock); 3722e02b9312SValentin Schneider mutex_unlock(&wq_pool_attach_mutex); 37239ab03be4SValentin Schneider } 3724692b4825STejun Heo 37251037de36SLai Jiangshan while ((worker = first_idle_worker(pool))) 3726e02b9312SValentin Schneider set_worker_dying(worker, &cull_list); 372729c91e99STejun Heo WARN_ON(pool->nr_workers || pool->nr_idle); 3728a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 372960f5a4bcSLai Jiangshan 3730e02b9312SValentin Schneider wake_dying_workers(&cull_list); 3731e02b9312SValentin Schneider 3732e02b9312SValentin Schneider if (!list_empty(&pool->workers) || !list_empty(&pool->dying_workers)) 373360f5a4bcSLai Jiangshan pool->detach_completion = &detach_completion; 37341258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 373560f5a4bcSLai Jiangshan 373660f5a4bcSLai Jiangshan if (pool->detach_completion) 373760f5a4bcSLai Jiangshan wait_for_completion(pool->detach_completion); 373860f5a4bcSLai Jiangshan 373929c91e99STejun Heo /* shut down the timers */ 374029c91e99STejun Heo del_timer_sync(&pool->idle_timer); 37413f959aa3SValentin Schneider cancel_work_sync(&pool->idle_cull_work); 374229c91e99STejun Heo del_timer_sync(&pool->mayday_timer); 374329c91e99STejun Heo 374424acfb71SThomas Gleixner /* RCU protected to allow dereferences from get_work_pool() */ 374525b00775SPaul E. McKenney call_rcu(&pool->rcu, rcu_free_pool); 374629c91e99STejun Heo } 374729c91e99STejun Heo 374829c91e99STejun Heo /** 374929c91e99STejun Heo * get_unbound_pool - get a worker_pool with the specified attributes 375029c91e99STejun Heo * @attrs: the attributes of the worker_pool to get 375129c91e99STejun Heo * 375229c91e99STejun Heo * Obtain a worker_pool which has the same attributes as @attrs, bump the 375329c91e99STejun Heo * reference count and return it. If there already is a matching 375429c91e99STejun Heo * worker_pool, it will be used; otherwise, this function attempts to 3755d185af30SYacine Belkadi * create a new one. 3756a892caccSTejun Heo * 3757a892caccSTejun Heo * Should be called with wq_pool_mutex held. 3758d185af30SYacine Belkadi * 3759d185af30SYacine Belkadi * Return: On success, a worker_pool with the same attributes as @attrs. 3760d185af30SYacine Belkadi * On failure, %NULL. 376129c91e99STejun Heo */ 376229c91e99STejun Heo static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) 376329c91e99STejun Heo { 376429c91e99STejun Heo u32 hash = wqattrs_hash(attrs); 376529c91e99STejun Heo struct worker_pool *pool; 3766f3f90ad4STejun Heo int node; 3767e2273584SXunlei Pang int target_node = NUMA_NO_NODE; 376829c91e99STejun Heo 3769a892caccSTejun Heo lockdep_assert_held(&wq_pool_mutex); 377029c91e99STejun Heo 377129c91e99STejun Heo /* do we already have a matching pool? */ 377229c91e99STejun Heo hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { 377329c91e99STejun Heo if (wqattrs_equal(pool->attrs, attrs)) { 377429c91e99STejun Heo pool->refcnt++; 37753fb1823cSLai Jiangshan return pool; 377629c91e99STejun Heo } 377729c91e99STejun Heo } 377829c91e99STejun Heo 3779e2273584SXunlei Pang /* if cpumask is contained inside a NUMA node, we belong to that node */ 3780e2273584SXunlei Pang if (wq_numa_enabled) { 3781e2273584SXunlei Pang for_each_node(node) { 3782e2273584SXunlei Pang if (cpumask_subset(attrs->cpumask, 3783e2273584SXunlei Pang wq_numa_possible_cpumask[node])) { 3784e2273584SXunlei Pang target_node = node; 3785e2273584SXunlei Pang break; 3786e2273584SXunlei Pang } 3787e2273584SXunlei Pang } 3788e2273584SXunlei Pang } 3789e2273584SXunlei Pang 379029c91e99STejun Heo /* nope, create a new one */ 3791e2273584SXunlei Pang pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, target_node); 379229c91e99STejun Heo if (!pool || init_worker_pool(pool) < 0) 379329c91e99STejun Heo goto fail; 379429c91e99STejun Heo 37958864b4e5STejun Heo lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ 379629c91e99STejun Heo copy_workqueue_attrs(pool->attrs, attrs); 3797e2273584SXunlei Pang pool->node = target_node; 379829c91e99STejun Heo 37992865a8fbSShaohua Li /* 38002865a8fbSShaohua Li * no_numa isn't a worker_pool attribute, always clear it. See 38012865a8fbSShaohua Li * 'struct workqueue_attrs' comments for detail. 38022865a8fbSShaohua Li */ 38032865a8fbSShaohua Li pool->attrs->no_numa = false; 38042865a8fbSShaohua Li 380529c91e99STejun Heo if (worker_pool_assign_id(pool) < 0) 380629c91e99STejun Heo goto fail; 380729c91e99STejun Heo 380829c91e99STejun Heo /* create and start the initial worker */ 38093347fa09STejun Heo if (wq_online && !create_worker(pool)) 381029c91e99STejun Heo goto fail; 381129c91e99STejun Heo 381229c91e99STejun Heo /* install */ 381329c91e99STejun Heo hash_add(unbound_pool_hash, &pool->hash_node, hash); 38143fb1823cSLai Jiangshan 381529c91e99STejun Heo return pool; 381629c91e99STejun Heo fail: 381729c91e99STejun Heo if (pool) 381829c91e99STejun Heo put_unbound_pool(pool); 381929c91e99STejun Heo return NULL; 382029c91e99STejun Heo } 382129c91e99STejun Heo 38228864b4e5STejun Heo static void rcu_free_pwq(struct rcu_head *rcu) 38238864b4e5STejun Heo { 38248864b4e5STejun Heo kmem_cache_free(pwq_cache, 38258864b4e5STejun Heo container_of(rcu, struct pool_workqueue, rcu)); 38268864b4e5STejun Heo } 38278864b4e5STejun Heo 38288864b4e5STejun Heo /* 38298864b4e5STejun Heo * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt 38308864b4e5STejun Heo * and needs to be destroyed. 38318864b4e5STejun Heo */ 38328864b4e5STejun Heo static void pwq_unbound_release_workfn(struct work_struct *work) 38338864b4e5STejun Heo { 38348864b4e5STejun Heo struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, 38358864b4e5STejun Heo unbound_release_work); 38368864b4e5STejun Heo struct workqueue_struct *wq = pwq->wq; 38378864b4e5STejun Heo struct worker_pool *pool = pwq->pool; 3838b42b0bddSYang Yingliang bool is_last = false; 38398864b4e5STejun Heo 3840b42b0bddSYang Yingliang /* 3841b42b0bddSYang Yingliang * when @pwq is not linked, it doesn't hold any reference to the 3842b42b0bddSYang Yingliang * @wq, and @wq is invalid to access. 3843b42b0bddSYang Yingliang */ 3844b42b0bddSYang Yingliang if (!list_empty(&pwq->pwqs_node)) { 38458864b4e5STejun Heo if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) 38468864b4e5STejun Heo return; 38478864b4e5STejun Heo 38483c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 38498864b4e5STejun Heo list_del_rcu(&pwq->pwqs_node); 3850bc0caf09STejun Heo is_last = list_empty(&wq->pwqs); 38513c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 3852b42b0bddSYang Yingliang } 38538864b4e5STejun Heo 3854a892caccSTejun Heo mutex_lock(&wq_pool_mutex); 38558864b4e5STejun Heo put_unbound_pool(pool); 3856a892caccSTejun Heo mutex_unlock(&wq_pool_mutex); 3857a892caccSTejun Heo 385825b00775SPaul E. McKenney call_rcu(&pwq->rcu, rcu_free_pwq); 38598864b4e5STejun Heo 38608864b4e5STejun Heo /* 38618864b4e5STejun Heo * If we're the last pwq going away, @wq is already dead and no one 3862e2dca7adSTejun Heo * is gonna access it anymore. Schedule RCU free. 38638864b4e5STejun Heo */ 3864669de8bdSBart Van Assche if (is_last) { 3865669de8bdSBart Van Assche wq_unregister_lockdep(wq); 386625b00775SPaul E. McKenney call_rcu(&wq->rcu, rcu_free_wq); 38676029a918STejun Heo } 3868669de8bdSBart Van Assche } 38698864b4e5STejun Heo 38700fbd95aaSTejun Heo /** 3871699ce097STejun Heo * pwq_adjust_max_active - update a pwq's max_active to the current setting 38720fbd95aaSTejun Heo * @pwq: target pool_workqueue 38730fbd95aaSTejun Heo * 3874699ce097STejun Heo * If @pwq isn't freezing, set @pwq->max_active to the associated 3875f97a4a1aSLai Jiangshan * workqueue's saved_max_active and activate inactive work items 3876699ce097STejun Heo * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. 38770fbd95aaSTejun Heo */ 3878699ce097STejun Heo static void pwq_adjust_max_active(struct pool_workqueue *pwq) 38790fbd95aaSTejun Heo { 3880699ce097STejun Heo struct workqueue_struct *wq = pwq->wq; 3881699ce097STejun Heo bool freezable = wq->flags & WQ_FREEZABLE; 38823347fa09STejun Heo unsigned long flags; 3883699ce097STejun Heo 3884699ce097STejun Heo /* for @wq->saved_max_active */ 3885a357fc03SLai Jiangshan lockdep_assert_held(&wq->mutex); 3886699ce097STejun Heo 3887699ce097STejun Heo /* fast exit for non-freezable wqs */ 3888699ce097STejun Heo if (!freezable && pwq->max_active == wq->saved_max_active) 3889699ce097STejun Heo return; 3890699ce097STejun Heo 38913347fa09STejun Heo /* this function can be called during early boot w/ irq disabled */ 3892a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irqsave(&pwq->pool->lock, flags); 3893699ce097STejun Heo 389474b414eaSLai Jiangshan /* 389574b414eaSLai Jiangshan * During [un]freezing, the caller is responsible for ensuring that 389674b414eaSLai Jiangshan * this function is called at least once after @workqueue_freezing 389774b414eaSLai Jiangshan * is updated and visible. 389874b414eaSLai Jiangshan */ 389974b414eaSLai Jiangshan if (!freezable || !workqueue_freezing) { 390001341fbdSYunfeng Ye bool kick = false; 390101341fbdSYunfeng Ye 3902699ce097STejun Heo pwq->max_active = wq->saved_max_active; 39030fbd95aaSTejun Heo 3904f97a4a1aSLai Jiangshan while (!list_empty(&pwq->inactive_works) && 390501341fbdSYunfeng Ye pwq->nr_active < pwq->max_active) { 3906f97a4a1aSLai Jiangshan pwq_activate_first_inactive(pwq); 390701341fbdSYunfeng Ye kick = true; 390801341fbdSYunfeng Ye } 3909951a078aSLai Jiangshan 3910951a078aSLai Jiangshan /* 3911951a078aSLai Jiangshan * Need to kick a worker after thawed or an unbound wq's 391201341fbdSYunfeng Ye * max_active is bumped. In realtime scenarios, always kicking a 391301341fbdSYunfeng Ye * worker will cause interference on the isolated cpu cores, so 391401341fbdSYunfeng Ye * let's kick iff work items were activated. 3915951a078aSLai Jiangshan */ 391601341fbdSYunfeng Ye if (kick) 3917951a078aSLai Jiangshan wake_up_worker(pwq->pool); 3918699ce097STejun Heo } else { 3919699ce097STejun Heo pwq->max_active = 0; 3920699ce097STejun Heo } 3921699ce097STejun Heo 3922a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); 39230fbd95aaSTejun Heo } 39240fbd95aaSTejun Heo 392567dc8325SCai Huoqing /* initialize newly allocated @pwq which is associated with @wq and @pool */ 3926f147f29eSTejun Heo static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, 3927f147f29eSTejun Heo struct worker_pool *pool) 3928d2c1d404STejun Heo { 3929d2c1d404STejun Heo BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); 3930d2c1d404STejun Heo 3931e50aba9aSTejun Heo memset(pwq, 0, sizeof(*pwq)); 3932e50aba9aSTejun Heo 3933d2c1d404STejun Heo pwq->pool = pool; 3934d2c1d404STejun Heo pwq->wq = wq; 3935d2c1d404STejun Heo pwq->flush_color = -1; 39368864b4e5STejun Heo pwq->refcnt = 1; 3937f97a4a1aSLai Jiangshan INIT_LIST_HEAD(&pwq->inactive_works); 39381befcf30STejun Heo INIT_LIST_HEAD(&pwq->pwqs_node); 3939d2c1d404STejun Heo INIT_LIST_HEAD(&pwq->mayday_node); 39408864b4e5STejun Heo INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); 3941f147f29eSTejun Heo } 3942d2c1d404STejun Heo 3943f147f29eSTejun Heo /* sync @pwq with the current state of its associated wq and link it */ 39441befcf30STejun Heo static void link_pwq(struct pool_workqueue *pwq) 3945f147f29eSTejun Heo { 3946f147f29eSTejun Heo struct workqueue_struct *wq = pwq->wq; 3947f147f29eSTejun Heo 3948f147f29eSTejun Heo lockdep_assert_held(&wq->mutex); 394975ccf595STejun Heo 39501befcf30STejun Heo /* may be called multiple times, ignore if already linked */ 39511befcf30STejun Heo if (!list_empty(&pwq->pwqs_node)) 39521befcf30STejun Heo return; 39531befcf30STejun Heo 395429b1cb41SLai Jiangshan /* set the matching work_color */ 395575ccf595STejun Heo pwq->work_color = wq->work_color; 3956983ca25eSTejun Heo 3957983ca25eSTejun Heo /* sync max_active to the current setting */ 3958983ca25eSTejun Heo pwq_adjust_max_active(pwq); 3959983ca25eSTejun Heo 3960983ca25eSTejun Heo /* link in @pwq */ 39619e8cd2f5STejun Heo list_add_rcu(&pwq->pwqs_node, &wq->pwqs); 3962df2d5ae4STejun Heo } 39636029a918STejun Heo 3964f147f29eSTejun Heo /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ 3965f147f29eSTejun Heo static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, 3966f147f29eSTejun Heo const struct workqueue_attrs *attrs) 3967f147f29eSTejun Heo { 3968f147f29eSTejun Heo struct worker_pool *pool; 3969f147f29eSTejun Heo struct pool_workqueue *pwq; 3970f147f29eSTejun Heo 3971f147f29eSTejun Heo lockdep_assert_held(&wq_pool_mutex); 3972f147f29eSTejun Heo 3973f147f29eSTejun Heo pool = get_unbound_pool(attrs); 3974f147f29eSTejun Heo if (!pool) 3975f147f29eSTejun Heo return NULL; 3976f147f29eSTejun Heo 3977e50aba9aSTejun Heo pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); 3978f147f29eSTejun Heo if (!pwq) { 3979f147f29eSTejun Heo put_unbound_pool(pool); 3980f147f29eSTejun Heo return NULL; 3981f147f29eSTejun Heo } 3982f147f29eSTejun Heo 3983f147f29eSTejun Heo init_pwq(pwq, wq, pool); 3984f147f29eSTejun Heo return pwq; 3985d2c1d404STejun Heo } 3986d2c1d404STejun Heo 39874c16bd32STejun Heo /** 398830186c6fSGong Zhaogang * wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node 3989042f7df1SLai Jiangshan * @attrs: the wq_attrs of the default pwq of the target workqueue 39904c16bd32STejun Heo * @node: the target NUMA node 39914c16bd32STejun Heo * @cpu_going_down: if >= 0, the CPU to consider as offline 39924c16bd32STejun Heo * @cpumask: outarg, the resulting cpumask 39934c16bd32STejun Heo * 39944c16bd32STejun Heo * Calculate the cpumask a workqueue with @attrs should use on @node. If 39954c16bd32STejun Heo * @cpu_going_down is >= 0, that cpu is considered offline during 3996d185af30SYacine Belkadi * calculation. The result is stored in @cpumask. 39974c16bd32STejun Heo * 39984c16bd32STejun Heo * If NUMA affinity is not enabled, @attrs->cpumask is always used. If 39994c16bd32STejun Heo * enabled and @node has online CPUs requested by @attrs, the returned 40004c16bd32STejun Heo * cpumask is the intersection of the possible CPUs of @node and 40014c16bd32STejun Heo * @attrs->cpumask. 40024c16bd32STejun Heo * 40034c16bd32STejun Heo * The caller is responsible for ensuring that the cpumask of @node stays 40044c16bd32STejun Heo * stable. 4005d185af30SYacine Belkadi * 4006d185af30SYacine Belkadi * Return: %true if the resulting @cpumask is different from @attrs->cpumask, 4007d185af30SYacine Belkadi * %false if equal. 40084c16bd32STejun Heo */ 40094c16bd32STejun Heo static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, 40104c16bd32STejun Heo int cpu_going_down, cpumask_t *cpumask) 40114c16bd32STejun Heo { 4012d55262c4STejun Heo if (!wq_numa_enabled || attrs->no_numa) 40134c16bd32STejun Heo goto use_dfl; 40144c16bd32STejun Heo 40154c16bd32STejun Heo /* does @node have any online CPUs @attrs wants? */ 40164c16bd32STejun Heo cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); 40174c16bd32STejun Heo if (cpu_going_down >= 0) 40184c16bd32STejun Heo cpumask_clear_cpu(cpu_going_down, cpumask); 40194c16bd32STejun Heo 40204c16bd32STejun Heo if (cpumask_empty(cpumask)) 40214c16bd32STejun Heo goto use_dfl; 40224c16bd32STejun Heo 40234c16bd32STejun Heo /* yeap, return possible CPUs in @node that @attrs wants */ 40244c16bd32STejun Heo cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); 40251ad0f0a7SMichael Bringmann 40261ad0f0a7SMichael Bringmann if (cpumask_empty(cpumask)) { 40271ad0f0a7SMichael Bringmann pr_warn_once("WARNING: workqueue cpumask: online intersect > " 40281ad0f0a7SMichael Bringmann "possible intersect\n"); 40291ad0f0a7SMichael Bringmann return false; 40301ad0f0a7SMichael Bringmann } 40311ad0f0a7SMichael Bringmann 40324c16bd32STejun Heo return !cpumask_equal(cpumask, attrs->cpumask); 40334c16bd32STejun Heo 40344c16bd32STejun Heo use_dfl: 40354c16bd32STejun Heo cpumask_copy(cpumask, attrs->cpumask); 40364c16bd32STejun Heo return false; 40374c16bd32STejun Heo } 40384c16bd32STejun Heo 40391befcf30STejun Heo /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ 40401befcf30STejun Heo static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, 40411befcf30STejun Heo int node, 40421befcf30STejun Heo struct pool_workqueue *pwq) 40431befcf30STejun Heo { 40441befcf30STejun Heo struct pool_workqueue *old_pwq; 40451befcf30STejun Heo 40465b95e1afSLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 40471befcf30STejun Heo lockdep_assert_held(&wq->mutex); 40481befcf30STejun Heo 40491befcf30STejun Heo /* link_pwq() can handle duplicate calls */ 40501befcf30STejun Heo link_pwq(pwq); 40511befcf30STejun Heo 40521befcf30STejun Heo old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); 40531befcf30STejun Heo rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); 40541befcf30STejun Heo return old_pwq; 40551befcf30STejun Heo } 40561befcf30STejun Heo 40572d5f0764SLai Jiangshan /* context to store the prepared attrs & pwqs before applying */ 40582d5f0764SLai Jiangshan struct apply_wqattrs_ctx { 40592d5f0764SLai Jiangshan struct workqueue_struct *wq; /* target workqueue */ 40602d5f0764SLai Jiangshan struct workqueue_attrs *attrs; /* attrs to apply */ 4061042f7df1SLai Jiangshan struct list_head list; /* queued for batching commit */ 40622d5f0764SLai Jiangshan struct pool_workqueue *dfl_pwq; 40632d5f0764SLai Jiangshan struct pool_workqueue *pwq_tbl[]; 40642d5f0764SLai Jiangshan }; 40652d5f0764SLai Jiangshan 40662d5f0764SLai Jiangshan /* free the resources after success or abort */ 40672d5f0764SLai Jiangshan static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) 40682d5f0764SLai Jiangshan { 40692d5f0764SLai Jiangshan if (ctx) { 40702d5f0764SLai Jiangshan int node; 40712d5f0764SLai Jiangshan 40722d5f0764SLai Jiangshan for_each_node(node) 40732d5f0764SLai Jiangshan put_pwq_unlocked(ctx->pwq_tbl[node]); 40742d5f0764SLai Jiangshan put_pwq_unlocked(ctx->dfl_pwq); 40752d5f0764SLai Jiangshan 40762d5f0764SLai Jiangshan free_workqueue_attrs(ctx->attrs); 40772d5f0764SLai Jiangshan 40782d5f0764SLai Jiangshan kfree(ctx); 40792d5f0764SLai Jiangshan } 40802d5f0764SLai Jiangshan } 40812d5f0764SLai Jiangshan 40822d5f0764SLai Jiangshan /* allocate the attrs and pwqs for later installation */ 40832d5f0764SLai Jiangshan static struct apply_wqattrs_ctx * 40842d5f0764SLai Jiangshan apply_wqattrs_prepare(struct workqueue_struct *wq, 408599c621efSLai Jiangshan const struct workqueue_attrs *attrs, 408699c621efSLai Jiangshan const cpumask_var_t unbound_cpumask) 40872d5f0764SLai Jiangshan { 40882d5f0764SLai Jiangshan struct apply_wqattrs_ctx *ctx; 40892d5f0764SLai Jiangshan struct workqueue_attrs *new_attrs, *tmp_attrs; 40902d5f0764SLai Jiangshan int node; 40912d5f0764SLai Jiangshan 40922d5f0764SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 40932d5f0764SLai Jiangshan 4094acafe7e3SKees Cook ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_node_ids), GFP_KERNEL); 40952d5f0764SLai Jiangshan 4096be69d00dSThomas Gleixner new_attrs = alloc_workqueue_attrs(); 4097be69d00dSThomas Gleixner tmp_attrs = alloc_workqueue_attrs(); 40982d5f0764SLai Jiangshan if (!ctx || !new_attrs || !tmp_attrs) 40992d5f0764SLai Jiangshan goto out_free; 41002d5f0764SLai Jiangshan 4101042f7df1SLai Jiangshan /* 410299c621efSLai Jiangshan * Calculate the attrs of the default pwq with unbound_cpumask 410399c621efSLai Jiangshan * which is wq_unbound_cpumask or to set to wq_unbound_cpumask. 4104042f7df1SLai Jiangshan * If the user configured cpumask doesn't overlap with the 4105042f7df1SLai Jiangshan * wq_unbound_cpumask, we fallback to the wq_unbound_cpumask. 4106042f7df1SLai Jiangshan */ 41072d5f0764SLai Jiangshan copy_workqueue_attrs(new_attrs, attrs); 410899c621efSLai Jiangshan cpumask_and(new_attrs->cpumask, new_attrs->cpumask, unbound_cpumask); 4109042f7df1SLai Jiangshan if (unlikely(cpumask_empty(new_attrs->cpumask))) 411099c621efSLai Jiangshan cpumask_copy(new_attrs->cpumask, unbound_cpumask); 41112d5f0764SLai Jiangshan 41122d5f0764SLai Jiangshan /* 41132d5f0764SLai Jiangshan * We may create multiple pwqs with differing cpumasks. Make a 41142d5f0764SLai Jiangshan * copy of @new_attrs which will be modified and used to obtain 41152d5f0764SLai Jiangshan * pools. 41162d5f0764SLai Jiangshan */ 41172d5f0764SLai Jiangshan copy_workqueue_attrs(tmp_attrs, new_attrs); 41182d5f0764SLai Jiangshan 41192d5f0764SLai Jiangshan /* 41202d5f0764SLai Jiangshan * If something goes wrong during CPU up/down, we'll fall back to 41212d5f0764SLai Jiangshan * the default pwq covering whole @attrs->cpumask. Always create 41222d5f0764SLai Jiangshan * it even if we don't use it immediately. 41232d5f0764SLai Jiangshan */ 41242d5f0764SLai Jiangshan ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs); 41252d5f0764SLai Jiangshan if (!ctx->dfl_pwq) 41262d5f0764SLai Jiangshan goto out_free; 41272d5f0764SLai Jiangshan 41282d5f0764SLai Jiangshan for_each_node(node) { 4129042f7df1SLai Jiangshan if (wq_calc_node_cpumask(new_attrs, node, -1, tmp_attrs->cpumask)) { 41302d5f0764SLai Jiangshan ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); 41312d5f0764SLai Jiangshan if (!ctx->pwq_tbl[node]) 41322d5f0764SLai Jiangshan goto out_free; 41332d5f0764SLai Jiangshan } else { 41342d5f0764SLai Jiangshan ctx->dfl_pwq->refcnt++; 41352d5f0764SLai Jiangshan ctx->pwq_tbl[node] = ctx->dfl_pwq; 41362d5f0764SLai Jiangshan } 41372d5f0764SLai Jiangshan } 41382d5f0764SLai Jiangshan 4139042f7df1SLai Jiangshan /* save the user configured attrs and sanitize it. */ 4140042f7df1SLai Jiangshan copy_workqueue_attrs(new_attrs, attrs); 4141042f7df1SLai Jiangshan cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); 41422d5f0764SLai Jiangshan ctx->attrs = new_attrs; 4143042f7df1SLai Jiangshan 41442d5f0764SLai Jiangshan ctx->wq = wq; 41452d5f0764SLai Jiangshan free_workqueue_attrs(tmp_attrs); 41462d5f0764SLai Jiangshan return ctx; 41472d5f0764SLai Jiangshan 41482d5f0764SLai Jiangshan out_free: 41492d5f0764SLai Jiangshan free_workqueue_attrs(tmp_attrs); 41502d5f0764SLai Jiangshan free_workqueue_attrs(new_attrs); 41512d5f0764SLai Jiangshan apply_wqattrs_cleanup(ctx); 41522d5f0764SLai Jiangshan return NULL; 41532d5f0764SLai Jiangshan } 41542d5f0764SLai Jiangshan 41552d5f0764SLai Jiangshan /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ 41562d5f0764SLai Jiangshan static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) 41572d5f0764SLai Jiangshan { 41582d5f0764SLai Jiangshan int node; 41592d5f0764SLai Jiangshan 41602d5f0764SLai Jiangshan /* all pwqs have been created successfully, let's install'em */ 41612d5f0764SLai Jiangshan mutex_lock(&ctx->wq->mutex); 41622d5f0764SLai Jiangshan 41632d5f0764SLai Jiangshan copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs); 41642d5f0764SLai Jiangshan 41652d5f0764SLai Jiangshan /* save the previous pwq and install the new one */ 41662d5f0764SLai Jiangshan for_each_node(node) 41672d5f0764SLai Jiangshan ctx->pwq_tbl[node] = numa_pwq_tbl_install(ctx->wq, node, 41682d5f0764SLai Jiangshan ctx->pwq_tbl[node]); 41692d5f0764SLai Jiangshan 41702d5f0764SLai Jiangshan /* @dfl_pwq might not have been used, ensure it's linked */ 41712d5f0764SLai Jiangshan link_pwq(ctx->dfl_pwq); 41722d5f0764SLai Jiangshan swap(ctx->wq->dfl_pwq, ctx->dfl_pwq); 41732d5f0764SLai Jiangshan 41742d5f0764SLai Jiangshan mutex_unlock(&ctx->wq->mutex); 41752d5f0764SLai Jiangshan } 41762d5f0764SLai Jiangshan 4177a0111cf6SLai Jiangshan static void apply_wqattrs_lock(void) 4178a0111cf6SLai Jiangshan { 4179a0111cf6SLai Jiangshan /* CPUs should stay stable across pwq creations and installations */ 4180ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 4181a0111cf6SLai Jiangshan mutex_lock(&wq_pool_mutex); 4182a0111cf6SLai Jiangshan } 4183a0111cf6SLai Jiangshan 4184a0111cf6SLai Jiangshan static void apply_wqattrs_unlock(void) 4185a0111cf6SLai Jiangshan { 4186a0111cf6SLai Jiangshan mutex_unlock(&wq_pool_mutex); 4187ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 4188a0111cf6SLai Jiangshan } 4189a0111cf6SLai Jiangshan 4190a0111cf6SLai Jiangshan static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, 4191a0111cf6SLai Jiangshan const struct workqueue_attrs *attrs) 4192a0111cf6SLai Jiangshan { 4193a0111cf6SLai Jiangshan struct apply_wqattrs_ctx *ctx; 4194a0111cf6SLai Jiangshan 4195a0111cf6SLai Jiangshan /* only unbound workqueues can change attributes */ 4196a0111cf6SLai Jiangshan if (WARN_ON(!(wq->flags & WQ_UNBOUND))) 4197a0111cf6SLai Jiangshan return -EINVAL; 4198a0111cf6SLai Jiangshan 4199a0111cf6SLai Jiangshan /* creating multiple pwqs breaks ordering guarantee */ 42000a94efb5STejun Heo if (!list_empty(&wq->pwqs)) { 42010a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 4202a0111cf6SLai Jiangshan return -EINVAL; 4203a0111cf6SLai Jiangshan 42040a94efb5STejun Heo wq->flags &= ~__WQ_ORDERED; 42050a94efb5STejun Heo } 42060a94efb5STejun Heo 420799c621efSLai Jiangshan ctx = apply_wqattrs_prepare(wq, attrs, wq_unbound_cpumask); 42086201171eSwanghaibin if (!ctx) 42096201171eSwanghaibin return -ENOMEM; 4210a0111cf6SLai Jiangshan 4211a0111cf6SLai Jiangshan /* the ctx has been prepared successfully, let's commit it */ 4212a0111cf6SLai Jiangshan apply_wqattrs_commit(ctx); 4213a0111cf6SLai Jiangshan apply_wqattrs_cleanup(ctx); 4214a0111cf6SLai Jiangshan 42156201171eSwanghaibin return 0; 4216a0111cf6SLai Jiangshan } 4217a0111cf6SLai Jiangshan 42189e8cd2f5STejun Heo /** 42199e8cd2f5STejun Heo * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue 42209e8cd2f5STejun Heo * @wq: the target workqueue 42219e8cd2f5STejun Heo * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() 42229e8cd2f5STejun Heo * 42234c16bd32STejun Heo * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA 42244c16bd32STejun Heo * machines, this function maps a separate pwq to each NUMA node with 42254c16bd32STejun Heo * possibles CPUs in @attrs->cpumask so that work items are affine to the 42264c16bd32STejun Heo * NUMA node it was issued on. Older pwqs are released as in-flight work 42274c16bd32STejun Heo * items finish. Note that a work item which repeatedly requeues itself 42284c16bd32STejun Heo * back-to-back will stay on its current pwq. 42299e8cd2f5STejun Heo * 4230d185af30SYacine Belkadi * Performs GFP_KERNEL allocations. 4231d185af30SYacine Belkadi * 4232ffd8bea8SSebastian Andrzej Siewior * Assumes caller has CPU hotplug read exclusion, i.e. cpus_read_lock(). 4233509b3204SDaniel Jordan * 4234d185af30SYacine Belkadi * Return: 0 on success and -errno on failure. 42359e8cd2f5STejun Heo */ 4236513c98d0SDaniel Jordan int apply_workqueue_attrs(struct workqueue_struct *wq, 42379e8cd2f5STejun Heo const struct workqueue_attrs *attrs) 42389e8cd2f5STejun Heo { 4239a0111cf6SLai Jiangshan int ret; 42409e8cd2f5STejun Heo 4241509b3204SDaniel Jordan lockdep_assert_cpus_held(); 4242509b3204SDaniel Jordan 4243509b3204SDaniel Jordan mutex_lock(&wq_pool_mutex); 4244a0111cf6SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 4245509b3204SDaniel Jordan mutex_unlock(&wq_pool_mutex); 42462d5f0764SLai Jiangshan 42472d5f0764SLai Jiangshan return ret; 42489e8cd2f5STejun Heo } 42499e8cd2f5STejun Heo 42504c16bd32STejun Heo /** 42514c16bd32STejun Heo * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug 42524c16bd32STejun Heo * @wq: the target workqueue 42534c16bd32STejun Heo * @cpu: the CPU coming up or going down 42544c16bd32STejun Heo * @online: whether @cpu is coming up or going down 42554c16bd32STejun Heo * 42564c16bd32STejun Heo * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and 42574c16bd32STejun Heo * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of 42584c16bd32STejun Heo * @wq accordingly. 42594c16bd32STejun Heo * 42604c16bd32STejun Heo * If NUMA affinity can't be adjusted due to memory allocation failure, it 42614c16bd32STejun Heo * falls back to @wq->dfl_pwq which may not be optimal but is always 42624c16bd32STejun Heo * correct. 42634c16bd32STejun Heo * 42644c16bd32STejun Heo * Note that when the last allowed CPU of a NUMA node goes offline for a 42654c16bd32STejun Heo * workqueue with a cpumask spanning multiple nodes, the workers which were 42664c16bd32STejun Heo * already executing the work items for the workqueue will lose their CPU 42674c16bd32STejun Heo * affinity and may execute on any CPU. This is similar to how per-cpu 42684c16bd32STejun Heo * workqueues behave on CPU_DOWN. If a workqueue user wants strict 42694c16bd32STejun Heo * affinity, it's the user's responsibility to flush the work item from 42704c16bd32STejun Heo * CPU_DOWN_PREPARE. 42714c16bd32STejun Heo */ 42724c16bd32STejun Heo static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, 42734c16bd32STejun Heo bool online) 42744c16bd32STejun Heo { 42754c16bd32STejun Heo int node = cpu_to_node(cpu); 42764c16bd32STejun Heo int cpu_off = online ? -1 : cpu; 42774c16bd32STejun Heo struct pool_workqueue *old_pwq = NULL, *pwq; 42784c16bd32STejun Heo struct workqueue_attrs *target_attrs; 42794c16bd32STejun Heo cpumask_t *cpumask; 42804c16bd32STejun Heo 42814c16bd32STejun Heo lockdep_assert_held(&wq_pool_mutex); 42824c16bd32STejun Heo 4283f7142ed4SLai Jiangshan if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND) || 4284f7142ed4SLai Jiangshan wq->unbound_attrs->no_numa) 42854c16bd32STejun Heo return; 42864c16bd32STejun Heo 42874c16bd32STejun Heo /* 42884c16bd32STejun Heo * We don't wanna alloc/free wq_attrs for each wq for each CPU. 42894c16bd32STejun Heo * Let's use a preallocated one. The following buf is protected by 42904c16bd32STejun Heo * CPU hotplug exclusion. 42914c16bd32STejun Heo */ 42924c16bd32STejun Heo target_attrs = wq_update_unbound_numa_attrs_buf; 42934c16bd32STejun Heo cpumask = target_attrs->cpumask; 42944c16bd32STejun Heo 42954c16bd32STejun Heo copy_workqueue_attrs(target_attrs, wq->unbound_attrs); 42964c16bd32STejun Heo pwq = unbound_pwq_by_node(wq, node); 42974c16bd32STejun Heo 42984c16bd32STejun Heo /* 42994c16bd32STejun Heo * Let's determine what needs to be done. If the target cpumask is 4300042f7df1SLai Jiangshan * different from the default pwq's, we need to compare it to @pwq's 4301042f7df1SLai Jiangshan * and create a new one if they don't match. If the target cpumask 4302042f7df1SLai Jiangshan * equals the default pwq's, the default pwq should be used. 43034c16bd32STejun Heo */ 4304042f7df1SLai Jiangshan if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) { 43054c16bd32STejun Heo if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) 4306f7142ed4SLai Jiangshan return; 43074c16bd32STejun Heo } else { 43084c16bd32STejun Heo goto use_dfl_pwq; 43094c16bd32STejun Heo } 43104c16bd32STejun Heo 43114c16bd32STejun Heo /* create a new pwq */ 43124c16bd32STejun Heo pwq = alloc_unbound_pwq(wq, target_attrs); 43134c16bd32STejun Heo if (!pwq) { 43142d916033SFabian Frederick pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", 43154c16bd32STejun Heo wq->name); 431677f300b1SDaeseok Youn goto use_dfl_pwq; 43174c16bd32STejun Heo } 43184c16bd32STejun Heo 4319f7142ed4SLai Jiangshan /* Install the new pwq. */ 43204c16bd32STejun Heo mutex_lock(&wq->mutex); 43214c16bd32STejun Heo old_pwq = numa_pwq_tbl_install(wq, node, pwq); 43224c16bd32STejun Heo goto out_unlock; 43234c16bd32STejun Heo 43244c16bd32STejun Heo use_dfl_pwq: 4325f7142ed4SLai Jiangshan mutex_lock(&wq->mutex); 4326a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&wq->dfl_pwq->pool->lock); 43274c16bd32STejun Heo get_pwq(wq->dfl_pwq); 4328a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&wq->dfl_pwq->pool->lock); 43294c16bd32STejun Heo old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); 43304c16bd32STejun Heo out_unlock: 43314c16bd32STejun Heo mutex_unlock(&wq->mutex); 43324c16bd32STejun Heo put_pwq_unlocked(old_pwq); 43334c16bd32STejun Heo } 43344c16bd32STejun Heo 433530cdf249STejun Heo static int alloc_and_link_pwqs(struct workqueue_struct *wq) 43361da177e4SLinus Torvalds { 433749e3cf44STejun Heo bool highpri = wq->flags & WQ_HIGHPRI; 43388a2b7538STejun Heo int cpu, ret; 4339e1d8aa9fSFrederic Weisbecker 434030cdf249STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 4341420c0ddbSTejun Heo wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); 4342420c0ddbSTejun Heo if (!wq->cpu_pwqs) 434330cdf249STejun Heo return -ENOMEM; 434430cdf249STejun Heo 434530cdf249STejun Heo for_each_possible_cpu(cpu) { 43467fb98ea7STejun Heo struct pool_workqueue *pwq = 43477fb98ea7STejun Heo per_cpu_ptr(wq->cpu_pwqs, cpu); 43487a62c2c8STejun Heo struct worker_pool *cpu_pools = 4349f02ae73aSTejun Heo per_cpu(cpu_worker_pools, cpu); 435030cdf249STejun Heo 4351f147f29eSTejun Heo init_pwq(pwq, wq, &cpu_pools[highpri]); 4352f147f29eSTejun Heo 4353f147f29eSTejun Heo mutex_lock(&wq->mutex); 43541befcf30STejun Heo link_pwq(pwq); 4355f147f29eSTejun Heo mutex_unlock(&wq->mutex); 435630cdf249STejun Heo } 435730cdf249STejun Heo return 0; 4358509b3204SDaniel Jordan } 4359509b3204SDaniel Jordan 4360ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 4361509b3204SDaniel Jordan if (wq->flags & __WQ_ORDERED) { 43628a2b7538STejun Heo ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); 43638a2b7538STejun Heo /* there should only be single pwq for ordering guarantee */ 43648a2b7538STejun Heo WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || 43658a2b7538STejun Heo wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), 43668a2b7538STejun Heo "ordering guarantee broken for workqueue %s\n", wq->name); 43679e8cd2f5STejun Heo } else { 4368509b3204SDaniel Jordan ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); 43699e8cd2f5STejun Heo } 4370ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 4371509b3204SDaniel Jordan 4372509b3204SDaniel Jordan return ret; 43730f900049STejun Heo } 43740f900049STejun Heo 4375f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 4376f3421797STejun Heo const char *name) 4377b71ab8c2STejun Heo { 4378f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 4379f3421797STejun Heo 4380f3421797STejun Heo if (max_active < 1 || max_active > lim) 4381044c782cSValentin Ilie pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 4382f3421797STejun Heo max_active, name, 1, lim); 4383b71ab8c2STejun Heo 4384f3421797STejun Heo return clamp_val(max_active, 1, lim); 4385b71ab8c2STejun Heo } 4386b71ab8c2STejun Heo 4387983c7515STejun Heo /* 4388983c7515STejun Heo * Workqueues which may be used during memory reclaim should have a rescuer 4389983c7515STejun Heo * to guarantee forward progress. 4390983c7515STejun Heo */ 4391983c7515STejun Heo static int init_rescuer(struct workqueue_struct *wq) 4392983c7515STejun Heo { 4393983c7515STejun Heo struct worker *rescuer; 4394b92b36eaSDan Carpenter int ret; 4395983c7515STejun Heo 4396983c7515STejun Heo if (!(wq->flags & WQ_MEM_RECLAIM)) 4397983c7515STejun Heo return 0; 4398983c7515STejun Heo 4399983c7515STejun Heo rescuer = alloc_worker(NUMA_NO_NODE); 44004c0736a7SPetr Mladek if (!rescuer) { 44014c0736a7SPetr Mladek pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n", 44024c0736a7SPetr Mladek wq->name); 4403983c7515STejun Heo return -ENOMEM; 44044c0736a7SPetr Mladek } 4405983c7515STejun Heo 4406983c7515STejun Heo rescuer->rescue_wq = wq; 4407983c7515STejun Heo rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name); 4408f187b697SSean Fu if (IS_ERR(rescuer->task)) { 4409b92b36eaSDan Carpenter ret = PTR_ERR(rescuer->task); 44104c0736a7SPetr Mladek pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe", 44114c0736a7SPetr Mladek wq->name, ERR_PTR(ret)); 4412983c7515STejun Heo kfree(rescuer); 4413b92b36eaSDan Carpenter return ret; 4414983c7515STejun Heo } 4415983c7515STejun Heo 4416983c7515STejun Heo wq->rescuer = rescuer; 4417983c7515STejun Heo kthread_bind_mask(rescuer->task, cpu_possible_mask); 4418983c7515STejun Heo wake_up_process(rescuer->task); 4419983c7515STejun Heo 4420983c7515STejun Heo return 0; 4421983c7515STejun Heo } 4422983c7515STejun Heo 4423a2775bbcSMathieu Malaterre __printf(1, 4) 4424669de8bdSBart Van Assche struct workqueue_struct *alloc_workqueue(const char *fmt, 442597e37d7bSTejun Heo unsigned int flags, 4426669de8bdSBart Van Assche int max_active, ...) 44273af24433SOleg Nesterov { 4428df2d5ae4STejun Heo size_t tbl_size = 0; 4429ecf6881fSTejun Heo va_list args; 44303af24433SOleg Nesterov struct workqueue_struct *wq; 443149e3cf44STejun Heo struct pool_workqueue *pwq; 4432b196be89STejun Heo 44335c0338c6STejun Heo /* 44345c0338c6STejun Heo * Unbound && max_active == 1 used to imply ordered, which is no 44355c0338c6STejun Heo * longer the case on NUMA machines due to per-node pools. While 44365c0338c6STejun Heo * alloc_ordered_workqueue() is the right way to create an ordered 44375c0338c6STejun Heo * workqueue, keep the previous behavior to avoid subtle breakages 44385c0338c6STejun Heo * on NUMA. 44395c0338c6STejun Heo */ 44405c0338c6STejun Heo if ((flags & WQ_UNBOUND) && max_active == 1) 44415c0338c6STejun Heo flags |= __WQ_ORDERED; 44425c0338c6STejun Heo 4443cee22a15SViresh Kumar /* see the comment above the definition of WQ_POWER_EFFICIENT */ 4444cee22a15SViresh Kumar if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) 4445cee22a15SViresh Kumar flags |= WQ_UNBOUND; 4446cee22a15SViresh Kumar 4447ecf6881fSTejun Heo /* allocate wq and format name */ 4448df2d5ae4STejun Heo if (flags & WQ_UNBOUND) 4449ddcb57e2SLai Jiangshan tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]); 4450df2d5ae4STejun Heo 4451df2d5ae4STejun Heo wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); 4452b196be89STejun Heo if (!wq) 4453d2c1d404STejun Heo return NULL; 4454b196be89STejun Heo 44556029a918STejun Heo if (flags & WQ_UNBOUND) { 4456be69d00dSThomas Gleixner wq->unbound_attrs = alloc_workqueue_attrs(); 44576029a918STejun Heo if (!wq->unbound_attrs) 44586029a918STejun Heo goto err_free_wq; 44596029a918STejun Heo } 44606029a918STejun Heo 4461669de8bdSBart Van Assche va_start(args, max_active); 4462ecf6881fSTejun Heo vsnprintf(wq->name, sizeof(wq->name), fmt, args); 4463b196be89STejun Heo va_end(args); 44643af24433SOleg Nesterov 4465d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 4466b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 44673af24433SOleg Nesterov 4468b196be89STejun Heo /* init wq */ 446997e37d7bSTejun Heo wq->flags = flags; 4470a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 44713c25a55dSLai Jiangshan mutex_init(&wq->mutex); 4472112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 0); 447330cdf249STejun Heo INIT_LIST_HEAD(&wq->pwqs); 447473f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 447573f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 4476493a1724STejun Heo INIT_LIST_HEAD(&wq->maydays); 44773af24433SOleg Nesterov 4478669de8bdSBart Van Assche wq_init_lockdep(wq); 4479cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 44803af24433SOleg Nesterov 448130cdf249STejun Heo if (alloc_and_link_pwqs(wq) < 0) 448282efcab3SBart Van Assche goto err_unreg_lockdep; 44831537663fSTejun Heo 448440c17f75STejun Heo if (wq_online && init_rescuer(wq) < 0) 4485d2c1d404STejun Heo goto err_destroy; 4486e22bee78STejun Heo 4487226223abSTejun Heo if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) 4488226223abSTejun Heo goto err_destroy; 4489226223abSTejun Heo 44906af8bf3dSOleg Nesterov /* 449168e13a67SLai Jiangshan * wq_pool_mutex protects global freeze state and workqueues list. 449268e13a67SLai Jiangshan * Grab it, adjust max_active and add the new @wq to workqueues 449368e13a67SLai Jiangshan * list. 44946af8bf3dSOleg Nesterov */ 449568e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4496a0a1a5fdSTejun Heo 4497a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 449849e3cf44STejun Heo for_each_pwq(pwq, wq) 4499699ce097STejun Heo pwq_adjust_max_active(pwq); 4500a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4501a0a1a5fdSTejun Heo 4502e2dca7adSTejun Heo list_add_tail_rcu(&wq->list, &workqueues); 4503a0a1a5fdSTejun Heo 450468e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 45053af24433SOleg Nesterov 45063af24433SOleg Nesterov return wq; 4507d2c1d404STejun Heo 450882efcab3SBart Van Assche err_unreg_lockdep: 4509009bb421SBart Van Assche wq_unregister_lockdep(wq); 4510009bb421SBart Van Assche wq_free_lockdep(wq); 451182efcab3SBart Van Assche err_free_wq: 45126029a918STejun Heo free_workqueue_attrs(wq->unbound_attrs); 45134690c4abSTejun Heo kfree(wq); 4514d2c1d404STejun Heo return NULL; 4515d2c1d404STejun Heo err_destroy: 4516d2c1d404STejun Heo destroy_workqueue(wq); 45174690c4abSTejun Heo return NULL; 45181da177e4SLinus Torvalds } 4519669de8bdSBart Van Assche EXPORT_SYMBOL_GPL(alloc_workqueue); 45201da177e4SLinus Torvalds 4521c29eb853STejun Heo static bool pwq_busy(struct pool_workqueue *pwq) 4522c29eb853STejun Heo { 4523c29eb853STejun Heo int i; 4524c29eb853STejun Heo 4525c29eb853STejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 4526c29eb853STejun Heo if (pwq->nr_in_flight[i]) 4527c29eb853STejun Heo return true; 4528c29eb853STejun Heo 4529c29eb853STejun Heo if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1)) 4530c29eb853STejun Heo return true; 4531f97a4a1aSLai Jiangshan if (pwq->nr_active || !list_empty(&pwq->inactive_works)) 4532c29eb853STejun Heo return true; 4533c29eb853STejun Heo 4534c29eb853STejun Heo return false; 4535c29eb853STejun Heo } 4536c29eb853STejun Heo 45373af24433SOleg Nesterov /** 45383af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 45393af24433SOleg Nesterov * @wq: target workqueue 45403af24433SOleg Nesterov * 45413af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 45423af24433SOleg Nesterov */ 45433af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 45443af24433SOleg Nesterov { 454549e3cf44STejun Heo struct pool_workqueue *pwq; 45464c16bd32STejun Heo int node; 45473af24433SOleg Nesterov 4548def98c84STejun Heo /* 4549def98c84STejun Heo * Remove it from sysfs first so that sanity check failure doesn't 4550def98c84STejun Heo * lead to sysfs name conflicts. 4551def98c84STejun Heo */ 4552def98c84STejun Heo workqueue_sysfs_unregister(wq); 4553def98c84STejun Heo 455433e3f0a3SRichard Clark /* mark the workqueue destruction is in progress */ 455533e3f0a3SRichard Clark mutex_lock(&wq->mutex); 455633e3f0a3SRichard Clark wq->flags |= __WQ_DESTROYING; 455733e3f0a3SRichard Clark mutex_unlock(&wq->mutex); 455833e3f0a3SRichard Clark 45599c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 45609c5a2ba7STejun Heo drain_workqueue(wq); 4561c8efcc25STejun Heo 4562def98c84STejun Heo /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ 4563def98c84STejun Heo if (wq->rescuer) { 4564def98c84STejun Heo struct worker *rescuer = wq->rescuer; 4565def98c84STejun Heo 4566def98c84STejun Heo /* this prevents new queueing */ 4567a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&wq_mayday_lock); 4568def98c84STejun Heo wq->rescuer = NULL; 4569a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&wq_mayday_lock); 4570def98c84STejun Heo 4571def98c84STejun Heo /* rescuer will empty maydays list before exiting */ 4572def98c84STejun Heo kthread_stop(rescuer->task); 45738efe1223STejun Heo kfree(rescuer); 4574def98c84STejun Heo } 4575def98c84STejun Heo 4576c29eb853STejun Heo /* 4577c29eb853STejun Heo * Sanity checks - grab all the locks so that we wait for all 4578c29eb853STejun Heo * in-flight operations which may do put_pwq(). 4579c29eb853STejun Heo */ 4580c29eb853STejun Heo mutex_lock(&wq_pool_mutex); 4581b09f4fd3SLai Jiangshan mutex_lock(&wq->mutex); 458249e3cf44STejun Heo for_each_pwq(pwq, wq) { 4583a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pwq->pool->lock); 4584c29eb853STejun Heo if (WARN_ON(pwq_busy(pwq))) { 45851d9a6159SKefeng Wang pr_warn("%s: %s has the following busy pwq\n", 4586e66b39afSTejun Heo __func__, wq->name); 4587c29eb853STejun Heo show_pwq(pwq); 4588a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pwq->pool->lock); 4589b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 4590c29eb853STejun Heo mutex_unlock(&wq_pool_mutex); 459155df0933SImran Khan show_one_workqueue(wq); 45926183c009STejun Heo return; 459376af4d93STejun Heo } 4594a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pwq->pool->lock); 459576af4d93STejun Heo } 4596b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 45976183c009STejun Heo 4598a0a1a5fdSTejun Heo /* 4599a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 4600a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 4601a0a1a5fdSTejun Heo */ 4602e2dca7adSTejun Heo list_del_rcu(&wq->list); 460368e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 46043af24433SOleg Nesterov 46058864b4e5STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 4606669de8bdSBart Van Assche wq_unregister_lockdep(wq); 460729c91e99STejun Heo /* 46088864b4e5STejun Heo * The base ref is never dropped on per-cpu pwqs. Directly 4609e2dca7adSTejun Heo * schedule RCU free. 461029c91e99STejun Heo */ 461125b00775SPaul E. McKenney call_rcu(&wq->rcu, rcu_free_wq); 46128864b4e5STejun Heo } else { 46138864b4e5STejun Heo /* 46148864b4e5STejun Heo * We're the sole accessor of @wq at this point. Directly 46154c16bd32STejun Heo * access numa_pwq_tbl[] and dfl_pwq to put the base refs. 46164c16bd32STejun Heo * @wq will be freed when the last pwq is released. 46178864b4e5STejun Heo */ 46184c16bd32STejun Heo for_each_node(node) { 46194c16bd32STejun Heo pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); 46204c16bd32STejun Heo RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); 46214c16bd32STejun Heo put_pwq_unlocked(pwq); 46224c16bd32STejun Heo } 46234c16bd32STejun Heo 46244c16bd32STejun Heo /* 46254c16bd32STejun Heo * Put dfl_pwq. @wq may be freed any time after dfl_pwq is 46264c16bd32STejun Heo * put. Don't access it afterwards. 46274c16bd32STejun Heo */ 46284c16bd32STejun Heo pwq = wq->dfl_pwq; 46294c16bd32STejun Heo wq->dfl_pwq = NULL; 4630dce90d47STejun Heo put_pwq_unlocked(pwq); 463129c91e99STejun Heo } 46323af24433SOleg Nesterov } 46333af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 46343af24433SOleg Nesterov 4635dcd989cbSTejun Heo /** 4636dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 4637dcd989cbSTejun Heo * @wq: target workqueue 4638dcd989cbSTejun Heo * @max_active: new max_active value. 4639dcd989cbSTejun Heo * 4640dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 4641dcd989cbSTejun Heo * 4642dcd989cbSTejun Heo * CONTEXT: 4643dcd989cbSTejun Heo * Don't call from IRQ context. 4644dcd989cbSTejun Heo */ 4645dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 4646dcd989cbSTejun Heo { 464749e3cf44STejun Heo struct pool_workqueue *pwq; 4648dcd989cbSTejun Heo 46498719dceaSTejun Heo /* disallow meddling with max_active for ordered workqueues */ 46500a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 46518719dceaSTejun Heo return; 46528719dceaSTejun Heo 4653f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 4654dcd989cbSTejun Heo 4655a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 4656dcd989cbSTejun Heo 46570a94efb5STejun Heo wq->flags &= ~__WQ_ORDERED; 4658dcd989cbSTejun Heo wq->saved_max_active = max_active; 4659dcd989cbSTejun Heo 4660699ce097STejun Heo for_each_pwq(pwq, wq) 4661699ce097STejun Heo pwq_adjust_max_active(pwq); 4662dcd989cbSTejun Heo 4663a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4664dcd989cbSTejun Heo } 4665dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 4666dcd989cbSTejun Heo 4667dcd989cbSTejun Heo /** 466827d4ee03SLukas Wunner * current_work - retrieve %current task's work struct 466927d4ee03SLukas Wunner * 467027d4ee03SLukas Wunner * Determine if %current task is a workqueue worker and what it's working on. 467127d4ee03SLukas Wunner * Useful to find out the context that the %current task is running in. 467227d4ee03SLukas Wunner * 467327d4ee03SLukas Wunner * Return: work struct if %current task is a workqueue worker, %NULL otherwise. 467427d4ee03SLukas Wunner */ 467527d4ee03SLukas Wunner struct work_struct *current_work(void) 467627d4ee03SLukas Wunner { 467727d4ee03SLukas Wunner struct worker *worker = current_wq_worker(); 467827d4ee03SLukas Wunner 467927d4ee03SLukas Wunner return worker ? worker->current_work : NULL; 468027d4ee03SLukas Wunner } 468127d4ee03SLukas Wunner EXPORT_SYMBOL(current_work); 468227d4ee03SLukas Wunner 468327d4ee03SLukas Wunner /** 4684e6267616STejun Heo * current_is_workqueue_rescuer - is %current workqueue rescuer? 4685e6267616STejun Heo * 4686e6267616STejun Heo * Determine whether %current is a workqueue rescuer. Can be used from 4687e6267616STejun Heo * work functions to determine whether it's being run off the rescuer task. 4688d185af30SYacine Belkadi * 4689d185af30SYacine Belkadi * Return: %true if %current is a workqueue rescuer. %false otherwise. 4690e6267616STejun Heo */ 4691e6267616STejun Heo bool current_is_workqueue_rescuer(void) 4692e6267616STejun Heo { 4693e6267616STejun Heo struct worker *worker = current_wq_worker(); 4694e6267616STejun Heo 46956a092dfdSLai Jiangshan return worker && worker->rescue_wq; 4696e6267616STejun Heo } 4697e6267616STejun Heo 4698e6267616STejun Heo /** 4699dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 4700dcd989cbSTejun Heo * @cpu: CPU in question 4701dcd989cbSTejun Heo * @wq: target workqueue 4702dcd989cbSTejun Heo * 4703dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 4704dcd989cbSTejun Heo * no synchronization around this function and the test result is 4705dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 4706dcd989cbSTejun Heo * 4707d3251859STejun Heo * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. 4708d3251859STejun Heo * Note that both per-cpu and unbound workqueues may be associated with 4709d3251859STejun Heo * multiple pool_workqueues which have separate congested states. A 4710d3251859STejun Heo * workqueue being congested on one CPU doesn't mean the workqueue is also 4711d3251859STejun Heo * contested on other CPUs / NUMA nodes. 4712d3251859STejun Heo * 4713d185af30SYacine Belkadi * Return: 4714dcd989cbSTejun Heo * %true if congested, %false otherwise. 4715dcd989cbSTejun Heo */ 4716d84ff051STejun Heo bool workqueue_congested(int cpu, struct workqueue_struct *wq) 4717dcd989cbSTejun Heo { 47187fb98ea7STejun Heo struct pool_workqueue *pwq; 471976af4d93STejun Heo bool ret; 472076af4d93STejun Heo 472124acfb71SThomas Gleixner rcu_read_lock(); 472224acfb71SThomas Gleixner preempt_disable(); 47237fb98ea7STejun Heo 4724d3251859STejun Heo if (cpu == WORK_CPU_UNBOUND) 4725d3251859STejun Heo cpu = smp_processor_id(); 4726d3251859STejun Heo 47277fb98ea7STejun Heo if (!(wq->flags & WQ_UNBOUND)) 47287fb98ea7STejun Heo pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); 47297fb98ea7STejun Heo else 4730df2d5ae4STejun Heo pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); 4731dcd989cbSTejun Heo 4732f97a4a1aSLai Jiangshan ret = !list_empty(&pwq->inactive_works); 473324acfb71SThomas Gleixner preempt_enable(); 473424acfb71SThomas Gleixner rcu_read_unlock(); 473576af4d93STejun Heo 473676af4d93STejun Heo return ret; 4737dcd989cbSTejun Heo } 4738dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 4739dcd989cbSTejun Heo 4740dcd989cbSTejun Heo /** 4741dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 4742dcd989cbSTejun Heo * @work: the work to be tested 4743dcd989cbSTejun Heo * 4744dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 4745dcd989cbSTejun Heo * synchronization around this function and the test result is 4746dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 4747dcd989cbSTejun Heo * 4748d185af30SYacine Belkadi * Return: 4749dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 4750dcd989cbSTejun Heo */ 4751dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 4752dcd989cbSTejun Heo { 4753fa1b54e6STejun Heo struct worker_pool *pool; 4754dcd989cbSTejun Heo unsigned long flags; 4755dcd989cbSTejun Heo unsigned int ret = 0; 4756dcd989cbSTejun Heo 4757dcd989cbSTejun Heo if (work_pending(work)) 4758dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 4759038366c5SLai Jiangshan 476024acfb71SThomas Gleixner rcu_read_lock(); 4761fa1b54e6STejun Heo pool = get_work_pool(work); 4762038366c5SLai Jiangshan if (pool) { 4763a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irqsave(&pool->lock, flags); 4764c9e7cf27STejun Heo if (find_worker_executing_work(pool, work)) 4765dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 4766a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irqrestore(&pool->lock, flags); 4767038366c5SLai Jiangshan } 476824acfb71SThomas Gleixner rcu_read_unlock(); 4769dcd989cbSTejun Heo 4770dcd989cbSTejun Heo return ret; 4771dcd989cbSTejun Heo } 4772dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 4773dcd989cbSTejun Heo 47743d1cb205STejun Heo /** 47753d1cb205STejun Heo * set_worker_desc - set description for the current work item 47763d1cb205STejun Heo * @fmt: printf-style format string 47773d1cb205STejun Heo * @...: arguments for the format string 47783d1cb205STejun Heo * 47793d1cb205STejun Heo * This function can be called by a running work function to describe what 47803d1cb205STejun Heo * the work item is about. If the worker task gets dumped, this 47813d1cb205STejun Heo * information will be printed out together to help debugging. The 47823d1cb205STejun Heo * description can be at most WORKER_DESC_LEN including the trailing '\0'. 47833d1cb205STejun Heo */ 47843d1cb205STejun Heo void set_worker_desc(const char *fmt, ...) 47853d1cb205STejun Heo { 47863d1cb205STejun Heo struct worker *worker = current_wq_worker(); 47873d1cb205STejun Heo va_list args; 47883d1cb205STejun Heo 47893d1cb205STejun Heo if (worker) { 47903d1cb205STejun Heo va_start(args, fmt); 47913d1cb205STejun Heo vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); 47923d1cb205STejun Heo va_end(args); 47933d1cb205STejun Heo } 47943d1cb205STejun Heo } 47955c750d58SSteffen Maier EXPORT_SYMBOL_GPL(set_worker_desc); 47963d1cb205STejun Heo 47973d1cb205STejun Heo /** 47983d1cb205STejun Heo * print_worker_info - print out worker information and description 47993d1cb205STejun Heo * @log_lvl: the log level to use when printing 48003d1cb205STejun Heo * @task: target task 48013d1cb205STejun Heo * 48023d1cb205STejun Heo * If @task is a worker and currently executing a work item, print out the 48033d1cb205STejun Heo * name of the workqueue being serviced and worker description set with 48043d1cb205STejun Heo * set_worker_desc() by the currently executing work item. 48053d1cb205STejun Heo * 48063d1cb205STejun Heo * This function can be safely called on any task as long as the 48073d1cb205STejun Heo * task_struct itself is accessible. While safe, this function isn't 48083d1cb205STejun Heo * synchronized and may print out mixups or garbages of limited length. 48093d1cb205STejun Heo */ 48103d1cb205STejun Heo void print_worker_info(const char *log_lvl, struct task_struct *task) 48113d1cb205STejun Heo { 48123d1cb205STejun Heo work_func_t *fn = NULL; 48133d1cb205STejun Heo char name[WQ_NAME_LEN] = { }; 48143d1cb205STejun Heo char desc[WORKER_DESC_LEN] = { }; 48153d1cb205STejun Heo struct pool_workqueue *pwq = NULL; 48163d1cb205STejun Heo struct workqueue_struct *wq = NULL; 48173d1cb205STejun Heo struct worker *worker; 48183d1cb205STejun Heo 48193d1cb205STejun Heo if (!(task->flags & PF_WQ_WORKER)) 48203d1cb205STejun Heo return; 48213d1cb205STejun Heo 48223d1cb205STejun Heo /* 48233d1cb205STejun Heo * This function is called without any synchronization and @task 48243d1cb205STejun Heo * could be in any state. Be careful with dereferences. 48253d1cb205STejun Heo */ 4826e700591aSPetr Mladek worker = kthread_probe_data(task); 48273d1cb205STejun Heo 48283d1cb205STejun Heo /* 48298bf89593STejun Heo * Carefully copy the associated workqueue's workfn, name and desc. 48308bf89593STejun Heo * Keep the original last '\0' in case the original is garbage. 48313d1cb205STejun Heo */ 4832fe557319SChristoph Hellwig copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn)); 4833fe557319SChristoph Hellwig copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq)); 4834fe557319SChristoph Hellwig copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq)); 4835fe557319SChristoph Hellwig copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1); 4836fe557319SChristoph Hellwig copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1); 48373d1cb205STejun Heo 48383d1cb205STejun Heo if (fn || name[0] || desc[0]) { 4839d75f773cSSakari Ailus printk("%sWorkqueue: %s %ps", log_lvl, name, fn); 48408bf89593STejun Heo if (strcmp(name, desc)) 48413d1cb205STejun Heo pr_cont(" (%s)", desc); 48423d1cb205STejun Heo pr_cont("\n"); 48433d1cb205STejun Heo } 48443d1cb205STejun Heo } 48453d1cb205STejun Heo 48463494fc30STejun Heo static void pr_cont_pool_info(struct worker_pool *pool) 48473494fc30STejun Heo { 48483494fc30STejun Heo pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask); 48493494fc30STejun Heo if (pool->node != NUMA_NO_NODE) 48503494fc30STejun Heo pr_cont(" node=%d", pool->node); 48513494fc30STejun Heo pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice); 48523494fc30STejun Heo } 48533494fc30STejun Heo 4854c76feb0dSPaul E. McKenney struct pr_cont_work_struct { 4855c76feb0dSPaul E. McKenney bool comma; 4856c76feb0dSPaul E. McKenney work_func_t func; 4857c76feb0dSPaul E. McKenney long ctr; 4858c76feb0dSPaul E. McKenney }; 4859c76feb0dSPaul E. McKenney 4860c76feb0dSPaul E. McKenney static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp) 4861c76feb0dSPaul E. McKenney { 4862c76feb0dSPaul E. McKenney if (!pcwsp->ctr) 4863c76feb0dSPaul E. McKenney goto out_record; 4864c76feb0dSPaul E. McKenney if (func == pcwsp->func) { 4865c76feb0dSPaul E. McKenney pcwsp->ctr++; 4866c76feb0dSPaul E. McKenney return; 4867c76feb0dSPaul E. McKenney } 4868c76feb0dSPaul E. McKenney if (pcwsp->ctr == 1) 4869c76feb0dSPaul E. McKenney pr_cont("%s %ps", pcwsp->comma ? "," : "", pcwsp->func); 4870c76feb0dSPaul E. McKenney else 4871c76feb0dSPaul E. McKenney pr_cont("%s %ld*%ps", pcwsp->comma ? "," : "", pcwsp->ctr, pcwsp->func); 4872c76feb0dSPaul E. McKenney pcwsp->ctr = 0; 4873c76feb0dSPaul E. McKenney out_record: 4874c76feb0dSPaul E. McKenney if ((long)func == -1L) 4875c76feb0dSPaul E. McKenney return; 4876c76feb0dSPaul E. McKenney pcwsp->comma = comma; 4877c76feb0dSPaul E. McKenney pcwsp->func = func; 4878c76feb0dSPaul E. McKenney pcwsp->ctr = 1; 4879c76feb0dSPaul E. McKenney } 4880c76feb0dSPaul E. McKenney 4881c76feb0dSPaul E. McKenney static void pr_cont_work(bool comma, struct work_struct *work, struct pr_cont_work_struct *pcwsp) 48823494fc30STejun Heo { 48833494fc30STejun Heo if (work->func == wq_barrier_func) { 48843494fc30STejun Heo struct wq_barrier *barr; 48853494fc30STejun Heo 48863494fc30STejun Heo barr = container_of(work, struct wq_barrier, work); 48873494fc30STejun Heo 4888c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); 48893494fc30STejun Heo pr_cont("%s BAR(%d)", comma ? "," : "", 48903494fc30STejun Heo task_pid_nr(barr->task)); 48913494fc30STejun Heo } else { 4892c76feb0dSPaul E. McKenney if (!comma) 4893c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); 4894c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, work->func, pcwsp); 48953494fc30STejun Heo } 48963494fc30STejun Heo } 48973494fc30STejun Heo 48983494fc30STejun Heo static void show_pwq(struct pool_workqueue *pwq) 48993494fc30STejun Heo { 4900c76feb0dSPaul E. McKenney struct pr_cont_work_struct pcws = { .ctr = 0, }; 49013494fc30STejun Heo struct worker_pool *pool = pwq->pool; 49023494fc30STejun Heo struct work_struct *work; 49033494fc30STejun Heo struct worker *worker; 49043494fc30STejun Heo bool has_in_flight = false, has_pending = false; 49053494fc30STejun Heo int bkt; 49063494fc30STejun Heo 49073494fc30STejun Heo pr_info(" pwq %d:", pool->id); 49083494fc30STejun Heo pr_cont_pool_info(pool); 49093494fc30STejun Heo 4910e66b39afSTejun Heo pr_cont(" active=%d/%d refcnt=%d%s\n", 4911e66b39afSTejun Heo pwq->nr_active, pwq->max_active, pwq->refcnt, 49123494fc30STejun Heo !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); 49133494fc30STejun Heo 49143494fc30STejun Heo hash_for_each(pool->busy_hash, bkt, worker, hentry) { 49153494fc30STejun Heo if (worker->current_pwq == pwq) { 49163494fc30STejun Heo has_in_flight = true; 49173494fc30STejun Heo break; 49183494fc30STejun Heo } 49193494fc30STejun Heo } 49203494fc30STejun Heo if (has_in_flight) { 49213494fc30STejun Heo bool comma = false; 49223494fc30STejun Heo 49233494fc30STejun Heo pr_info(" in-flight:"); 49243494fc30STejun Heo hash_for_each(pool->busy_hash, bkt, worker, hentry) { 49253494fc30STejun Heo if (worker->current_pwq != pwq) 49263494fc30STejun Heo continue; 49273494fc30STejun Heo 4928d75f773cSSakari Ailus pr_cont("%s %d%s:%ps", comma ? "," : "", 49293494fc30STejun Heo task_pid_nr(worker->task), 493030ae2fc0STejun Heo worker->rescue_wq ? "(RESCUER)" : "", 49313494fc30STejun Heo worker->current_func); 49323494fc30STejun Heo list_for_each_entry(work, &worker->scheduled, entry) 4933c76feb0dSPaul E. McKenney pr_cont_work(false, work, &pcws); 4934c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 49353494fc30STejun Heo comma = true; 49363494fc30STejun Heo } 49373494fc30STejun Heo pr_cont("\n"); 49383494fc30STejun Heo } 49393494fc30STejun Heo 49403494fc30STejun Heo list_for_each_entry(work, &pool->worklist, entry) { 49413494fc30STejun Heo if (get_work_pwq(work) == pwq) { 49423494fc30STejun Heo has_pending = true; 49433494fc30STejun Heo break; 49443494fc30STejun Heo } 49453494fc30STejun Heo } 49463494fc30STejun Heo if (has_pending) { 49473494fc30STejun Heo bool comma = false; 49483494fc30STejun Heo 49493494fc30STejun Heo pr_info(" pending:"); 49503494fc30STejun Heo list_for_each_entry(work, &pool->worklist, entry) { 49513494fc30STejun Heo if (get_work_pwq(work) != pwq) 49523494fc30STejun Heo continue; 49533494fc30STejun Heo 4954c76feb0dSPaul E. McKenney pr_cont_work(comma, work, &pcws); 49553494fc30STejun Heo comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); 49563494fc30STejun Heo } 4957c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 49583494fc30STejun Heo pr_cont("\n"); 49593494fc30STejun Heo } 49603494fc30STejun Heo 4961f97a4a1aSLai Jiangshan if (!list_empty(&pwq->inactive_works)) { 49623494fc30STejun Heo bool comma = false; 49633494fc30STejun Heo 4964f97a4a1aSLai Jiangshan pr_info(" inactive:"); 4965f97a4a1aSLai Jiangshan list_for_each_entry(work, &pwq->inactive_works, entry) { 4966c76feb0dSPaul E. McKenney pr_cont_work(comma, work, &pcws); 49673494fc30STejun Heo comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); 49683494fc30STejun Heo } 4969c76feb0dSPaul E. McKenney pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); 49703494fc30STejun Heo pr_cont("\n"); 49713494fc30STejun Heo } 49723494fc30STejun Heo } 49733494fc30STejun Heo 49743494fc30STejun Heo /** 497555df0933SImran Khan * show_one_workqueue - dump state of specified workqueue 497655df0933SImran Khan * @wq: workqueue whose state will be printed 49773494fc30STejun Heo */ 497855df0933SImran Khan void show_one_workqueue(struct workqueue_struct *wq) 49793494fc30STejun Heo { 49803494fc30STejun Heo struct pool_workqueue *pwq; 49813494fc30STejun Heo bool idle = true; 498255df0933SImran Khan unsigned long flags; 49833494fc30STejun Heo 49843494fc30STejun Heo for_each_pwq(pwq, wq) { 4985f97a4a1aSLai Jiangshan if (pwq->nr_active || !list_empty(&pwq->inactive_works)) { 49863494fc30STejun Heo idle = false; 49873494fc30STejun Heo break; 49883494fc30STejun Heo } 49893494fc30STejun Heo } 499055df0933SImran Khan if (idle) /* Nothing to print for idle workqueue */ 499155df0933SImran Khan return; 49923494fc30STejun Heo 49933494fc30STejun Heo pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags); 49943494fc30STejun Heo 49953494fc30STejun Heo for_each_pwq(pwq, wq) { 4996a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irqsave(&pwq->pool->lock, flags); 499757116ce1SJohan Hovold if (pwq->nr_active || !list_empty(&pwq->inactive_works)) { 499857116ce1SJohan Hovold /* 499957116ce1SJohan Hovold * Defer printing to avoid deadlocks in console 500057116ce1SJohan Hovold * drivers that queue work while holding locks 500157116ce1SJohan Hovold * also taken in their write paths. 500257116ce1SJohan Hovold */ 500357116ce1SJohan Hovold printk_deferred_enter(); 50043494fc30STejun Heo show_pwq(pwq); 500557116ce1SJohan Hovold printk_deferred_exit(); 500657116ce1SJohan Hovold } 5007a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); 500862635ea8SSergey Senozhatsky /* 500962635ea8SSergey Senozhatsky * We could be printing a lot from atomic context, e.g. 501055df0933SImran Khan * sysrq-t -> show_all_workqueues(). Avoid triggering 501162635ea8SSergey Senozhatsky * hard lockup. 501262635ea8SSergey Senozhatsky */ 501362635ea8SSergey Senozhatsky touch_nmi_watchdog(); 50143494fc30STejun Heo } 501555df0933SImran Khan 50163494fc30STejun Heo } 50173494fc30STejun Heo 501855df0933SImran Khan /** 501955df0933SImran Khan * show_one_worker_pool - dump state of specified worker pool 502055df0933SImran Khan * @pool: worker pool whose state will be printed 502155df0933SImran Khan */ 502255df0933SImran Khan static void show_one_worker_pool(struct worker_pool *pool) 502355df0933SImran Khan { 50243494fc30STejun Heo struct worker *worker; 50253494fc30STejun Heo bool first = true; 502655df0933SImran Khan unsigned long flags; 5027335a42ebSPetr Mladek unsigned long hung = 0; 50283494fc30STejun Heo 5029a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irqsave(&pool->lock, flags); 50303494fc30STejun Heo if (pool->nr_workers == pool->nr_idle) 50313494fc30STejun Heo goto next_pool; 5032335a42ebSPetr Mladek 5033335a42ebSPetr Mladek /* How long the first pending work is waiting for a worker. */ 5034335a42ebSPetr Mladek if (!list_empty(&pool->worklist)) 5035335a42ebSPetr Mladek hung = jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000; 5036335a42ebSPetr Mladek 503757116ce1SJohan Hovold /* 503857116ce1SJohan Hovold * Defer printing to avoid deadlocks in console drivers that 503957116ce1SJohan Hovold * queue work while holding locks also taken in their write 504057116ce1SJohan Hovold * paths. 504157116ce1SJohan Hovold */ 504257116ce1SJohan Hovold printk_deferred_enter(); 50433494fc30STejun Heo pr_info("pool %d:", pool->id); 50443494fc30STejun Heo pr_cont_pool_info(pool); 5045335a42ebSPetr Mladek pr_cont(" hung=%lus workers=%d", hung, pool->nr_workers); 50463494fc30STejun Heo if (pool->manager) 50473494fc30STejun Heo pr_cont(" manager: %d", 50483494fc30STejun Heo task_pid_nr(pool->manager->task)); 50493494fc30STejun Heo list_for_each_entry(worker, &pool->idle_list, entry) { 50503494fc30STejun Heo pr_cont(" %s%d", first ? "idle: " : "", 50513494fc30STejun Heo task_pid_nr(worker->task)); 50523494fc30STejun Heo first = false; 50533494fc30STejun Heo } 50543494fc30STejun Heo pr_cont("\n"); 505557116ce1SJohan Hovold printk_deferred_exit(); 50563494fc30STejun Heo next_pool: 5057a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irqrestore(&pool->lock, flags); 505862635ea8SSergey Senozhatsky /* 505962635ea8SSergey Senozhatsky * We could be printing a lot from atomic context, e.g. 506055df0933SImran Khan * sysrq-t -> show_all_workqueues(). Avoid triggering 506162635ea8SSergey Senozhatsky * hard lockup. 506262635ea8SSergey Senozhatsky */ 506362635ea8SSergey Senozhatsky touch_nmi_watchdog(); 506455df0933SImran Khan 50653494fc30STejun Heo } 50663494fc30STejun Heo 506755df0933SImran Khan /** 506855df0933SImran Khan * show_all_workqueues - dump workqueue state 506955df0933SImran Khan * 5070704bc669SJungseung Lee * Called from a sysrq handler and prints out all busy workqueues and pools. 507155df0933SImran Khan */ 507255df0933SImran Khan void show_all_workqueues(void) 507355df0933SImran Khan { 507455df0933SImran Khan struct workqueue_struct *wq; 507555df0933SImran Khan struct worker_pool *pool; 507655df0933SImran Khan int pi; 507755df0933SImran Khan 507855df0933SImran Khan rcu_read_lock(); 507955df0933SImran Khan 508055df0933SImran Khan pr_info("Showing busy workqueues and worker pools:\n"); 508155df0933SImran Khan 508255df0933SImran Khan list_for_each_entry_rcu(wq, &workqueues, list) 508355df0933SImran Khan show_one_workqueue(wq); 508455df0933SImran Khan 508555df0933SImran Khan for_each_pool(pool, pi) 508655df0933SImran Khan show_one_worker_pool(pool); 508755df0933SImran Khan 508824acfb71SThomas Gleixner rcu_read_unlock(); 50893494fc30STejun Heo } 50903494fc30STejun Heo 5091704bc669SJungseung Lee /** 5092704bc669SJungseung Lee * show_freezable_workqueues - dump freezable workqueue state 5093704bc669SJungseung Lee * 5094704bc669SJungseung Lee * Called from try_to_freeze_tasks() and prints out all freezable workqueues 5095704bc669SJungseung Lee * still busy. 5096704bc669SJungseung Lee */ 5097704bc669SJungseung Lee void show_freezable_workqueues(void) 5098704bc669SJungseung Lee { 5099704bc669SJungseung Lee struct workqueue_struct *wq; 5100704bc669SJungseung Lee 5101704bc669SJungseung Lee rcu_read_lock(); 5102704bc669SJungseung Lee 5103704bc669SJungseung Lee pr_info("Showing freezable workqueues that are still busy:\n"); 5104704bc669SJungseung Lee 5105704bc669SJungseung Lee list_for_each_entry_rcu(wq, &workqueues, list) { 5106704bc669SJungseung Lee if (!(wq->flags & WQ_FREEZABLE)) 5107704bc669SJungseung Lee continue; 5108704bc669SJungseung Lee show_one_workqueue(wq); 5109704bc669SJungseung Lee } 5110704bc669SJungseung Lee 5111704bc669SJungseung Lee rcu_read_unlock(); 5112704bc669SJungseung Lee } 5113704bc669SJungseung Lee 51146b59808bSTejun Heo /* used to show worker information through /proc/PID/{comm,stat,status} */ 51156b59808bSTejun Heo void wq_worker_comm(char *buf, size_t size, struct task_struct *task) 51166b59808bSTejun Heo { 51176b59808bSTejun Heo int off; 51186b59808bSTejun Heo 51196b59808bSTejun Heo /* always show the actual comm */ 51206b59808bSTejun Heo off = strscpy(buf, task->comm, size); 51216b59808bSTejun Heo if (off < 0) 51226b59808bSTejun Heo return; 51236b59808bSTejun Heo 5124197f6accSTejun Heo /* stabilize PF_WQ_WORKER and worker pool association */ 51256b59808bSTejun Heo mutex_lock(&wq_pool_attach_mutex); 51266b59808bSTejun Heo 5127197f6accSTejun Heo if (task->flags & PF_WQ_WORKER) { 5128197f6accSTejun Heo struct worker *worker = kthread_data(task); 5129197f6accSTejun Heo struct worker_pool *pool = worker->pool; 51306b59808bSTejun Heo 51316b59808bSTejun Heo if (pool) { 5132a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 51336b59808bSTejun Heo /* 5134197f6accSTejun Heo * ->desc tracks information (wq name or 5135197f6accSTejun Heo * set_worker_desc()) for the latest execution. If 5136197f6accSTejun Heo * current, prepend '+', otherwise '-'. 51376b59808bSTejun Heo */ 51386b59808bSTejun Heo if (worker->desc[0] != '\0') { 51396b59808bSTejun Heo if (worker->current_work) 51406b59808bSTejun Heo scnprintf(buf + off, size - off, "+%s", 51416b59808bSTejun Heo worker->desc); 51426b59808bSTejun Heo else 51436b59808bSTejun Heo scnprintf(buf + off, size - off, "-%s", 51446b59808bSTejun Heo worker->desc); 51456b59808bSTejun Heo } 5146a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 51476b59808bSTejun Heo } 5148197f6accSTejun Heo } 51496b59808bSTejun Heo 51506b59808bSTejun Heo mutex_unlock(&wq_pool_attach_mutex); 51516b59808bSTejun Heo } 51526b59808bSTejun Heo 515366448bc2SMathieu Malaterre #ifdef CONFIG_SMP 515466448bc2SMathieu Malaterre 5155db7bccf4STejun Heo /* 5156db7bccf4STejun Heo * CPU hotplug. 5157db7bccf4STejun Heo * 5158e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 5159112202d9STejun Heo * are a lot of assumptions on strong associations among work, pwq and 5160706026c2STejun Heo * pool which make migrating pending and scheduled works very 5161e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 516294cf58bbSTejun Heo * worker pools serve mix of short, long and very long running works making 5163e22bee78STejun Heo * blocked draining impractical. 5164e22bee78STejun Heo * 516524647570STejun Heo * This is solved by allowing the pools to be disassociated from the CPU 5166628c78e7STejun Heo * running as an unbound one and allowing it to be reattached later if the 5167628c78e7STejun Heo * cpu comes back online. 5168db7bccf4STejun Heo */ 5169db7bccf4STejun Heo 5170e8b3f8dbSLai Jiangshan static void unbind_workers(int cpu) 5171db7bccf4STejun Heo { 51724ce62e9eSTejun Heo struct worker_pool *pool; 5173db7bccf4STejun Heo struct worker *worker; 5174db7bccf4STejun Heo 5175f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 51761258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 5177a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 5178e22bee78STejun Heo 5179f2d5a0eeSTejun Heo /* 518092f9c5c4SLai Jiangshan * We've blocked all attach/detach operations. Make all workers 518194cf58bbSTejun Heo * unbound and set DISASSOCIATED. Before this, all workers 518211b45b0bSLai Jiangshan * must be on the cpu. After this, they may become diasporas. 5183b4ac9384SLai Jiangshan * And the preemption disabled section in their sched callbacks 5184b4ac9384SLai Jiangshan * are guaranteed to see WORKER_UNBOUND since the code here 5185b4ac9384SLai Jiangshan * is on the same cpu. 5186f2d5a0eeSTejun Heo */ 5187da028469SLai Jiangshan for_each_pool_worker(worker, pool) 5188403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 5189db7bccf4STejun Heo 519024647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 5191f2d5a0eeSTejun Heo 5192e22bee78STejun Heo /* 5193989442d7SLai Jiangshan * The handling of nr_running in sched callbacks are disabled 5194989442d7SLai Jiangshan * now. Zap nr_running. After this, nr_running stays zero and 5195989442d7SLai Jiangshan * need_more_worker() and keep_working() are always true as 5196989442d7SLai Jiangshan * long as the worklist is not empty. This pool now behaves as 5197989442d7SLai Jiangshan * an unbound (in terms of concurrency management) pool which 5198eb283428SLai Jiangshan * are served by workers tied to the pool. 5199e22bee78STejun Heo */ 5200bc35f7efSLai Jiangshan pool->nr_running = 0; 5201eb283428SLai Jiangshan 5202eb283428SLai Jiangshan /* 5203eb283428SLai Jiangshan * With concurrency management just turned off, a busy 5204eb283428SLai Jiangshan * worker blocking could lead to lengthy stalls. Kick off 5205eb283428SLai Jiangshan * unbound chain execution of currently pending work items. 5206eb283428SLai Jiangshan */ 5207eb283428SLai Jiangshan wake_up_worker(pool); 5208989442d7SLai Jiangshan 5209a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 5210989442d7SLai Jiangshan 5211793777bcSValentin Schneider for_each_pool_worker(worker, pool) 5212793777bcSValentin Schneider unbind_worker(worker); 5213989442d7SLai Jiangshan 5214989442d7SLai Jiangshan mutex_unlock(&wq_pool_attach_mutex); 5215eb283428SLai Jiangshan } 5216db7bccf4STejun Heo } 5217db7bccf4STejun Heo 5218bd7c089eSTejun Heo /** 5219bd7c089eSTejun Heo * rebind_workers - rebind all workers of a pool to the associated CPU 5220bd7c089eSTejun Heo * @pool: pool of interest 5221bd7c089eSTejun Heo * 5222a9ab775bSTejun Heo * @pool->cpu is coming online. Rebind all workers to the CPU. 5223bd7c089eSTejun Heo */ 5224bd7c089eSTejun Heo static void rebind_workers(struct worker_pool *pool) 5225bd7c089eSTejun Heo { 5226a9ab775bSTejun Heo struct worker *worker; 5227bd7c089eSTejun Heo 52281258fae7STejun Heo lockdep_assert_held(&wq_pool_attach_mutex); 5229bd7c089eSTejun Heo 5230bd7c089eSTejun Heo /* 5231a9ab775bSTejun Heo * Restore CPU affinity of all workers. As all idle workers should 5232a9ab775bSTejun Heo * be on the run-queue of the associated CPU before any local 5233402dd89dSShailendra Verma * wake-ups for concurrency management happen, restore CPU affinity 5234a9ab775bSTejun Heo * of all workers first and then clear UNBOUND. As we're called 5235a9ab775bSTejun Heo * from CPU_ONLINE, the following shouldn't fail. 5236bd7c089eSTejun Heo */ 5237c63a2e52SValentin Schneider for_each_pool_worker(worker, pool) { 5238c63a2e52SValentin Schneider kthread_set_per_cpu(worker->task, pool->cpu); 5239c63a2e52SValentin Schneider WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, 5240c63a2e52SValentin Schneider pool->attrs->cpumask) < 0); 5241c63a2e52SValentin Schneider } 5242a9ab775bSTejun Heo 5243a9b8a985SSebastian Andrzej Siewior raw_spin_lock_irq(&pool->lock); 5244f7c17d26SWanpeng Li 52453de5e884SLai Jiangshan pool->flags &= ~POOL_DISASSOCIATED; 5246a9ab775bSTejun Heo 5247da028469SLai Jiangshan for_each_pool_worker(worker, pool) { 5248a9ab775bSTejun Heo unsigned int worker_flags = worker->flags; 5249a9ab775bSTejun Heo 5250a9ab775bSTejun Heo /* 5251a9ab775bSTejun Heo * We want to clear UNBOUND but can't directly call 5252a9ab775bSTejun Heo * worker_clr_flags() or adjust nr_running. Atomically 5253a9ab775bSTejun Heo * replace UNBOUND with another NOT_RUNNING flag REBOUND. 5254a9ab775bSTejun Heo * @worker will clear REBOUND using worker_clr_flags() when 5255a9ab775bSTejun Heo * it initiates the next execution cycle thus restoring 5256a9ab775bSTejun Heo * concurrency management. Note that when or whether 5257a9ab775bSTejun Heo * @worker clears REBOUND doesn't affect correctness. 5258a9ab775bSTejun Heo * 5259c95491edSMark Rutland * WRITE_ONCE() is necessary because @worker->flags may be 5260a9ab775bSTejun Heo * tested without holding any lock in 52616d25be57SThomas Gleixner * wq_worker_running(). Without it, NOT_RUNNING test may 5262a9ab775bSTejun Heo * fail incorrectly leading to premature concurrency 5263a9ab775bSTejun Heo * management operations. 5264bd7c089eSTejun Heo */ 5265a9ab775bSTejun Heo WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); 5266a9ab775bSTejun Heo worker_flags |= WORKER_REBOUND; 5267a9ab775bSTejun Heo worker_flags &= ~WORKER_UNBOUND; 5268c95491edSMark Rutland WRITE_ONCE(worker->flags, worker_flags); 5269bd7c089eSTejun Heo } 5270a9ab775bSTejun Heo 5271a9b8a985SSebastian Andrzej Siewior raw_spin_unlock_irq(&pool->lock); 5272bd7c089eSTejun Heo } 5273bd7c089eSTejun Heo 52747dbc725eSTejun Heo /** 52757dbc725eSTejun Heo * restore_unbound_workers_cpumask - restore cpumask of unbound workers 52767dbc725eSTejun Heo * @pool: unbound pool of interest 52777dbc725eSTejun Heo * @cpu: the CPU which is coming up 52787dbc725eSTejun Heo * 52797dbc725eSTejun Heo * An unbound pool may end up with a cpumask which doesn't have any online 52807dbc725eSTejun Heo * CPUs. When a worker of such pool get scheduled, the scheduler resets 52817dbc725eSTejun Heo * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any 52827dbc725eSTejun Heo * online CPU before, cpus_allowed of all its workers should be restored. 52837dbc725eSTejun Heo */ 52847dbc725eSTejun Heo static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) 52857dbc725eSTejun Heo { 52867dbc725eSTejun Heo static cpumask_t cpumask; 52877dbc725eSTejun Heo struct worker *worker; 52887dbc725eSTejun Heo 52891258fae7STejun Heo lockdep_assert_held(&wq_pool_attach_mutex); 52907dbc725eSTejun Heo 52917dbc725eSTejun Heo /* is @cpu allowed for @pool? */ 52927dbc725eSTejun Heo if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) 52937dbc725eSTejun Heo return; 52947dbc725eSTejun Heo 52957dbc725eSTejun Heo cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); 52967dbc725eSTejun Heo 52977dbc725eSTejun Heo /* as we're called from CPU_ONLINE, the following shouldn't fail */ 5298da028469SLai Jiangshan for_each_pool_worker(worker, pool) 5299d945b5e9SPeter Zijlstra WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0); 53007dbc725eSTejun Heo } 53017dbc725eSTejun Heo 53027ee681b2SThomas Gleixner int workqueue_prepare_cpu(unsigned int cpu) 53031da177e4SLinus Torvalds { 53044ce62e9eSTejun Heo struct worker_pool *pool; 53051da177e4SLinus Torvalds 5306f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 53073ce63377STejun Heo if (pool->nr_workers) 53083ce63377STejun Heo continue; 5309051e1850SLai Jiangshan if (!create_worker(pool)) 53107ee681b2SThomas Gleixner return -ENOMEM; 53113af24433SOleg Nesterov } 53127ee681b2SThomas Gleixner return 0; 53137ee681b2SThomas Gleixner } 53141da177e4SLinus Torvalds 53157ee681b2SThomas Gleixner int workqueue_online_cpu(unsigned int cpu) 53167ee681b2SThomas Gleixner { 53177ee681b2SThomas Gleixner struct worker_pool *pool; 53187ee681b2SThomas Gleixner struct workqueue_struct *wq; 53197ee681b2SThomas Gleixner int pi; 53207ee681b2SThomas Gleixner 532168e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 53227dbc725eSTejun Heo 53237dbc725eSTejun Heo for_each_pool(pool, pi) { 53241258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 532594cf58bbSTejun Heo 5326f05b558dSLai Jiangshan if (pool->cpu == cpu) 532794cf58bbSTejun Heo rebind_workers(pool); 5328f05b558dSLai Jiangshan else if (pool->cpu < 0) 53297dbc725eSTejun Heo restore_unbound_workers_cpumask(pool, cpu); 533094cf58bbSTejun Heo 53311258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 533294cf58bbSTejun Heo } 53337dbc725eSTejun Heo 53344c16bd32STejun Heo /* update NUMA affinity of unbound workqueues */ 53354c16bd32STejun Heo list_for_each_entry(wq, &workqueues, list) 53364c16bd32STejun Heo wq_update_unbound_numa(wq, cpu, true); 53374c16bd32STejun Heo 533868e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 53397ee681b2SThomas Gleixner return 0; 534065758202STejun Heo } 534165758202STejun Heo 53427ee681b2SThomas Gleixner int workqueue_offline_cpu(unsigned int cpu) 534365758202STejun Heo { 53444c16bd32STejun Heo struct workqueue_struct *wq; 53458db25e78STejun Heo 53464c16bd32STejun Heo /* unbinding per-cpu workers should happen on the local CPU */ 5347e8b3f8dbSLai Jiangshan if (WARN_ON(cpu != smp_processor_id())) 5348e8b3f8dbSLai Jiangshan return -1; 5349e8b3f8dbSLai Jiangshan 5350e8b3f8dbSLai Jiangshan unbind_workers(cpu); 53514c16bd32STejun Heo 53524c16bd32STejun Heo /* update NUMA affinity of unbound workqueues */ 53534c16bd32STejun Heo mutex_lock(&wq_pool_mutex); 53544c16bd32STejun Heo list_for_each_entry(wq, &workqueues, list) 53554c16bd32STejun Heo wq_update_unbound_numa(wq, cpu, false); 53564c16bd32STejun Heo mutex_unlock(&wq_pool_mutex); 53574c16bd32STejun Heo 53587ee681b2SThomas Gleixner return 0; 535965758202STejun Heo } 536065758202STejun Heo 53612d3854a3SRusty Russell struct work_for_cpu { 5362ed48ece2STejun Heo struct work_struct work; 53632d3854a3SRusty Russell long (*fn)(void *); 53642d3854a3SRusty Russell void *arg; 53652d3854a3SRusty Russell long ret; 53662d3854a3SRusty Russell }; 53672d3854a3SRusty Russell 5368ed48ece2STejun Heo static void work_for_cpu_fn(struct work_struct *work) 53692d3854a3SRusty Russell { 5370ed48ece2STejun Heo struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); 5371ed48ece2STejun Heo 53722d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 53732d3854a3SRusty Russell } 53742d3854a3SRusty Russell 53752d3854a3SRusty Russell /** 537622aceb31SAnna-Maria Gleixner * work_on_cpu - run a function in thread context on a particular cpu 53772d3854a3SRusty Russell * @cpu: the cpu to run on 53782d3854a3SRusty Russell * @fn: the function to run 53792d3854a3SRusty Russell * @arg: the function arg 53802d3854a3SRusty Russell * 538131ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 53826b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 5383d185af30SYacine Belkadi * 5384d185af30SYacine Belkadi * Return: The value @fn returns. 53852d3854a3SRusty Russell */ 5386d84ff051STejun Heo long work_on_cpu(int cpu, long (*fn)(void *), void *arg) 53872d3854a3SRusty Russell { 5388ed48ece2STejun Heo struct work_for_cpu wfc = { .fn = fn, .arg = arg }; 53892d3854a3SRusty Russell 5390ed48ece2STejun Heo INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); 5391ed48ece2STejun Heo schedule_work_on(cpu, &wfc.work); 539212997d1aSBjorn Helgaas flush_work(&wfc.work); 5393440a1136SChuansheng Liu destroy_work_on_stack(&wfc.work); 53942d3854a3SRusty Russell return wfc.ret; 53952d3854a3SRusty Russell } 53962d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 53970e8d6a93SThomas Gleixner 53980e8d6a93SThomas Gleixner /** 53990e8d6a93SThomas Gleixner * work_on_cpu_safe - run a function in thread context on a particular cpu 54000e8d6a93SThomas Gleixner * @cpu: the cpu to run on 54010e8d6a93SThomas Gleixner * @fn: the function to run 54020e8d6a93SThomas Gleixner * @arg: the function argument 54030e8d6a93SThomas Gleixner * 54040e8d6a93SThomas Gleixner * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold 54050e8d6a93SThomas Gleixner * any locks which would prevent @fn from completing. 54060e8d6a93SThomas Gleixner * 54070e8d6a93SThomas Gleixner * Return: The value @fn returns. 54080e8d6a93SThomas Gleixner */ 54090e8d6a93SThomas Gleixner long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg) 54100e8d6a93SThomas Gleixner { 54110e8d6a93SThomas Gleixner long ret = -ENODEV; 54120e8d6a93SThomas Gleixner 5413ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 54140e8d6a93SThomas Gleixner if (cpu_online(cpu)) 54150e8d6a93SThomas Gleixner ret = work_on_cpu(cpu, fn, arg); 5416ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 54170e8d6a93SThomas Gleixner return ret; 54180e8d6a93SThomas Gleixner } 54190e8d6a93SThomas Gleixner EXPORT_SYMBOL_GPL(work_on_cpu_safe); 54202d3854a3SRusty Russell #endif /* CONFIG_SMP */ 54212d3854a3SRusty Russell 5422a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 5423e7577c50SRusty Russell 5424a0a1a5fdSTejun Heo /** 5425a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 5426a0a1a5fdSTejun Heo * 542758a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 5428f97a4a1aSLai Jiangshan * workqueues will queue new works to their inactive_works list instead of 5429706026c2STejun Heo * pool->worklist. 5430a0a1a5fdSTejun Heo * 5431a0a1a5fdSTejun Heo * CONTEXT: 5432a357fc03SLai Jiangshan * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 5433a0a1a5fdSTejun Heo */ 5434a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 5435a0a1a5fdSTejun Heo { 543624b8a847STejun Heo struct workqueue_struct *wq; 543724b8a847STejun Heo struct pool_workqueue *pwq; 5438a0a1a5fdSTejun Heo 543968e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5440a0a1a5fdSTejun Heo 54416183c009STejun Heo WARN_ON_ONCE(workqueue_freezing); 5442a0a1a5fdSTejun Heo workqueue_freezing = true; 5443a0a1a5fdSTejun Heo 544424b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 5445a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 5446699ce097STejun Heo for_each_pwq(pwq, wq) 5447699ce097STejun Heo pwq_adjust_max_active(pwq); 5448a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 5449a1056305STejun Heo } 54505bcab335STejun Heo 545168e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5452a0a1a5fdSTejun Heo } 5453a0a1a5fdSTejun Heo 5454a0a1a5fdSTejun Heo /** 545558a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 5456a0a1a5fdSTejun Heo * 5457a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 5458a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 5459a0a1a5fdSTejun Heo * 5460a0a1a5fdSTejun Heo * CONTEXT: 546168e13a67SLai Jiangshan * Grabs and releases wq_pool_mutex. 5462a0a1a5fdSTejun Heo * 5463d185af30SYacine Belkadi * Return: 546458a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 546558a69cb4STejun Heo * is complete. 5466a0a1a5fdSTejun Heo */ 5467a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 5468a0a1a5fdSTejun Heo { 5469a0a1a5fdSTejun Heo bool busy = false; 547024b8a847STejun Heo struct workqueue_struct *wq; 547124b8a847STejun Heo struct pool_workqueue *pwq; 5472a0a1a5fdSTejun Heo 547368e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5474a0a1a5fdSTejun Heo 54756183c009STejun Heo WARN_ON_ONCE(!workqueue_freezing); 5476a0a1a5fdSTejun Heo 547724b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 547824b8a847STejun Heo if (!(wq->flags & WQ_FREEZABLE)) 547924b8a847STejun Heo continue; 5480a0a1a5fdSTejun Heo /* 5481a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 5482a0a1a5fdSTejun Heo * to peek without lock. 5483a0a1a5fdSTejun Heo */ 548424acfb71SThomas Gleixner rcu_read_lock(); 548524b8a847STejun Heo for_each_pwq(pwq, wq) { 54866183c009STejun Heo WARN_ON_ONCE(pwq->nr_active < 0); 5487112202d9STejun Heo if (pwq->nr_active) { 5488a0a1a5fdSTejun Heo busy = true; 548924acfb71SThomas Gleixner rcu_read_unlock(); 5490a0a1a5fdSTejun Heo goto out_unlock; 5491a0a1a5fdSTejun Heo } 5492a0a1a5fdSTejun Heo } 549324acfb71SThomas Gleixner rcu_read_unlock(); 5494a0a1a5fdSTejun Heo } 5495a0a1a5fdSTejun Heo out_unlock: 549668e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5497a0a1a5fdSTejun Heo return busy; 5498a0a1a5fdSTejun Heo } 5499a0a1a5fdSTejun Heo 5500a0a1a5fdSTejun Heo /** 5501a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 5502a0a1a5fdSTejun Heo * 5503a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 5504706026c2STejun Heo * frozen works are transferred to their respective pool worklists. 5505a0a1a5fdSTejun Heo * 5506a0a1a5fdSTejun Heo * CONTEXT: 5507a357fc03SLai Jiangshan * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 5508a0a1a5fdSTejun Heo */ 5509a0a1a5fdSTejun Heo void thaw_workqueues(void) 5510a0a1a5fdSTejun Heo { 551124b8a847STejun Heo struct workqueue_struct *wq; 551224b8a847STejun Heo struct pool_workqueue *pwq; 5513a0a1a5fdSTejun Heo 551468e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5515a0a1a5fdSTejun Heo 5516a0a1a5fdSTejun Heo if (!workqueue_freezing) 5517a0a1a5fdSTejun Heo goto out_unlock; 5518a0a1a5fdSTejun Heo 551974b414eaSLai Jiangshan workqueue_freezing = false; 552024b8a847STejun Heo 552124b8a847STejun Heo /* restore max_active and repopulate worklist */ 552224b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 5523a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 5524699ce097STejun Heo for_each_pwq(pwq, wq) 5525699ce097STejun Heo pwq_adjust_max_active(pwq); 5526a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 552724b8a847STejun Heo } 552824b8a847STejun Heo 5529a0a1a5fdSTejun Heo out_unlock: 553068e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5531a0a1a5fdSTejun Heo } 5532a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 5533a0a1a5fdSTejun Heo 553499c621efSLai Jiangshan static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask) 5535042f7df1SLai Jiangshan { 5536042f7df1SLai Jiangshan LIST_HEAD(ctxs); 5537042f7df1SLai Jiangshan int ret = 0; 5538042f7df1SLai Jiangshan struct workqueue_struct *wq; 5539042f7df1SLai Jiangshan struct apply_wqattrs_ctx *ctx, *n; 5540042f7df1SLai Jiangshan 5541042f7df1SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 5542042f7df1SLai Jiangshan 5543042f7df1SLai Jiangshan list_for_each_entry(wq, &workqueues, list) { 5544042f7df1SLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 5545042f7df1SLai Jiangshan continue; 5546042f7df1SLai Jiangshan /* creating multiple pwqs breaks ordering guarantee */ 5547042f7df1SLai Jiangshan if (wq->flags & __WQ_ORDERED) 5548042f7df1SLai Jiangshan continue; 5549042f7df1SLai Jiangshan 555099c621efSLai Jiangshan ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs, unbound_cpumask); 5551042f7df1SLai Jiangshan if (!ctx) { 5552042f7df1SLai Jiangshan ret = -ENOMEM; 5553042f7df1SLai Jiangshan break; 5554042f7df1SLai Jiangshan } 5555042f7df1SLai Jiangshan 5556042f7df1SLai Jiangshan list_add_tail(&ctx->list, &ctxs); 5557042f7df1SLai Jiangshan } 5558042f7df1SLai Jiangshan 5559042f7df1SLai Jiangshan list_for_each_entry_safe(ctx, n, &ctxs, list) { 5560042f7df1SLai Jiangshan if (!ret) 5561042f7df1SLai Jiangshan apply_wqattrs_commit(ctx); 5562042f7df1SLai Jiangshan apply_wqattrs_cleanup(ctx); 5563042f7df1SLai Jiangshan } 5564042f7df1SLai Jiangshan 556599c621efSLai Jiangshan if (!ret) { 556699c621efSLai Jiangshan mutex_lock(&wq_pool_attach_mutex); 556799c621efSLai Jiangshan cpumask_copy(wq_unbound_cpumask, unbound_cpumask); 556899c621efSLai Jiangshan mutex_unlock(&wq_pool_attach_mutex); 556999c621efSLai Jiangshan } 5570042f7df1SLai Jiangshan return ret; 5571042f7df1SLai Jiangshan } 5572042f7df1SLai Jiangshan 5573042f7df1SLai Jiangshan /** 5574042f7df1SLai Jiangshan * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask 5575042f7df1SLai Jiangshan * @cpumask: the cpumask to set 5576042f7df1SLai Jiangshan * 5577042f7df1SLai Jiangshan * The low-level workqueues cpumask is a global cpumask that limits 5578042f7df1SLai Jiangshan * the affinity of all unbound workqueues. This function check the @cpumask 5579042f7df1SLai Jiangshan * and apply it to all unbound workqueues and updates all pwqs of them. 5580042f7df1SLai Jiangshan * 558167dc8325SCai Huoqing * Return: 0 - Success 5582042f7df1SLai Jiangshan * -EINVAL - Invalid @cpumask 5583042f7df1SLai Jiangshan * -ENOMEM - Failed to allocate memory for attrs or pwqs. 5584042f7df1SLai Jiangshan */ 5585042f7df1SLai Jiangshan int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) 5586042f7df1SLai Jiangshan { 5587042f7df1SLai Jiangshan int ret = -EINVAL; 5588042f7df1SLai Jiangshan 5589c98a9805STal Shorer /* 5590c98a9805STal Shorer * Not excluding isolated cpus on purpose. 5591c98a9805STal Shorer * If the user wishes to include them, we allow that. 5592c98a9805STal Shorer */ 5593042f7df1SLai Jiangshan cpumask_and(cpumask, cpumask, cpu_possible_mask); 5594042f7df1SLai Jiangshan if (!cpumask_empty(cpumask)) { 5595a0111cf6SLai Jiangshan apply_wqattrs_lock(); 5596d25302e4SMenglong Dong if (cpumask_equal(cpumask, wq_unbound_cpumask)) { 5597d25302e4SMenglong Dong ret = 0; 5598d25302e4SMenglong Dong goto out_unlock; 5599d25302e4SMenglong Dong } 5600d25302e4SMenglong Dong 560199c621efSLai Jiangshan ret = workqueue_apply_unbound_cpumask(cpumask); 5602042f7df1SLai Jiangshan 5603d25302e4SMenglong Dong out_unlock: 5604a0111cf6SLai Jiangshan apply_wqattrs_unlock(); 5605042f7df1SLai Jiangshan } 5606042f7df1SLai Jiangshan 5607042f7df1SLai Jiangshan return ret; 5608042f7df1SLai Jiangshan } 5609042f7df1SLai Jiangshan 56106ba94429SFrederic Weisbecker #ifdef CONFIG_SYSFS 56116ba94429SFrederic Weisbecker /* 56126ba94429SFrederic Weisbecker * Workqueues with WQ_SYSFS flag set is visible to userland via 56136ba94429SFrederic Weisbecker * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the 56146ba94429SFrederic Weisbecker * following attributes. 56156ba94429SFrederic Weisbecker * 56166ba94429SFrederic Weisbecker * per_cpu RO bool : whether the workqueue is per-cpu or unbound 56176ba94429SFrederic Weisbecker * max_active RW int : maximum number of in-flight work items 56186ba94429SFrederic Weisbecker * 56196ba94429SFrederic Weisbecker * Unbound workqueues have the following extra attributes. 56206ba94429SFrederic Weisbecker * 56219a19b463SWang Long * pool_ids RO int : the associated pool IDs for each node 56226ba94429SFrederic Weisbecker * nice RW int : nice value of the workers 56236ba94429SFrederic Weisbecker * cpumask RW mask : bitmask of allowed CPUs for the workers 56249a19b463SWang Long * numa RW bool : whether enable NUMA affinity 56256ba94429SFrederic Weisbecker */ 56266ba94429SFrederic Weisbecker struct wq_device { 56276ba94429SFrederic Weisbecker struct workqueue_struct *wq; 56286ba94429SFrederic Weisbecker struct device dev; 56296ba94429SFrederic Weisbecker }; 56306ba94429SFrederic Weisbecker 56316ba94429SFrederic Weisbecker static struct workqueue_struct *dev_to_wq(struct device *dev) 56326ba94429SFrederic Weisbecker { 56336ba94429SFrederic Weisbecker struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 56346ba94429SFrederic Weisbecker 56356ba94429SFrederic Weisbecker return wq_dev->wq; 56366ba94429SFrederic Weisbecker } 56376ba94429SFrederic Weisbecker 56386ba94429SFrederic Weisbecker static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, 56396ba94429SFrederic Weisbecker char *buf) 56406ba94429SFrederic Weisbecker { 56416ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 56426ba94429SFrederic Weisbecker 56436ba94429SFrederic Weisbecker return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); 56446ba94429SFrederic Weisbecker } 56456ba94429SFrederic Weisbecker static DEVICE_ATTR_RO(per_cpu); 56466ba94429SFrederic Weisbecker 56476ba94429SFrederic Weisbecker static ssize_t max_active_show(struct device *dev, 56486ba94429SFrederic Weisbecker struct device_attribute *attr, char *buf) 56496ba94429SFrederic Weisbecker { 56506ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 56516ba94429SFrederic Weisbecker 56526ba94429SFrederic Weisbecker return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); 56536ba94429SFrederic Weisbecker } 56546ba94429SFrederic Weisbecker 56556ba94429SFrederic Weisbecker static ssize_t max_active_store(struct device *dev, 56566ba94429SFrederic Weisbecker struct device_attribute *attr, const char *buf, 56576ba94429SFrederic Weisbecker size_t count) 56586ba94429SFrederic Weisbecker { 56596ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 56606ba94429SFrederic Weisbecker int val; 56616ba94429SFrederic Weisbecker 56626ba94429SFrederic Weisbecker if (sscanf(buf, "%d", &val) != 1 || val <= 0) 56636ba94429SFrederic Weisbecker return -EINVAL; 56646ba94429SFrederic Weisbecker 56656ba94429SFrederic Weisbecker workqueue_set_max_active(wq, val); 56666ba94429SFrederic Weisbecker return count; 56676ba94429SFrederic Weisbecker } 56686ba94429SFrederic Weisbecker static DEVICE_ATTR_RW(max_active); 56696ba94429SFrederic Weisbecker 56706ba94429SFrederic Weisbecker static struct attribute *wq_sysfs_attrs[] = { 56716ba94429SFrederic Weisbecker &dev_attr_per_cpu.attr, 56726ba94429SFrederic Weisbecker &dev_attr_max_active.attr, 56736ba94429SFrederic Weisbecker NULL, 56746ba94429SFrederic Weisbecker }; 56756ba94429SFrederic Weisbecker ATTRIBUTE_GROUPS(wq_sysfs); 56766ba94429SFrederic Weisbecker 56776ba94429SFrederic Weisbecker static ssize_t wq_pool_ids_show(struct device *dev, 56786ba94429SFrederic Weisbecker struct device_attribute *attr, char *buf) 56796ba94429SFrederic Weisbecker { 56806ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 56816ba94429SFrederic Weisbecker const char *delim = ""; 56826ba94429SFrederic Weisbecker int node, written = 0; 56836ba94429SFrederic Weisbecker 5684ffd8bea8SSebastian Andrzej Siewior cpus_read_lock(); 568524acfb71SThomas Gleixner rcu_read_lock(); 56866ba94429SFrederic Weisbecker for_each_node(node) { 56876ba94429SFrederic Weisbecker written += scnprintf(buf + written, PAGE_SIZE - written, 56886ba94429SFrederic Weisbecker "%s%d:%d", delim, node, 56896ba94429SFrederic Weisbecker unbound_pwq_by_node(wq, node)->pool->id); 56906ba94429SFrederic Weisbecker delim = " "; 56916ba94429SFrederic Weisbecker } 56926ba94429SFrederic Weisbecker written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); 569324acfb71SThomas Gleixner rcu_read_unlock(); 5694ffd8bea8SSebastian Andrzej Siewior cpus_read_unlock(); 56956ba94429SFrederic Weisbecker 56966ba94429SFrederic Weisbecker return written; 56976ba94429SFrederic Weisbecker } 56986ba94429SFrederic Weisbecker 56996ba94429SFrederic Weisbecker static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, 57006ba94429SFrederic Weisbecker char *buf) 57016ba94429SFrederic Weisbecker { 57026ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 57036ba94429SFrederic Weisbecker int written; 57046ba94429SFrederic Weisbecker 57056ba94429SFrederic Weisbecker mutex_lock(&wq->mutex); 57066ba94429SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); 57076ba94429SFrederic Weisbecker mutex_unlock(&wq->mutex); 57086ba94429SFrederic Weisbecker 57096ba94429SFrederic Weisbecker return written; 57106ba94429SFrederic Weisbecker } 57116ba94429SFrederic Weisbecker 57126ba94429SFrederic Weisbecker /* prepare workqueue_attrs for sysfs store operations */ 57136ba94429SFrederic Weisbecker static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) 57146ba94429SFrederic Weisbecker { 57156ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 57166ba94429SFrederic Weisbecker 5717899a94feSLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 5718899a94feSLai Jiangshan 5719be69d00dSThomas Gleixner attrs = alloc_workqueue_attrs(); 57206ba94429SFrederic Weisbecker if (!attrs) 57216ba94429SFrederic Weisbecker return NULL; 57226ba94429SFrederic Weisbecker 57236ba94429SFrederic Weisbecker copy_workqueue_attrs(attrs, wq->unbound_attrs); 57246ba94429SFrederic Weisbecker return attrs; 57256ba94429SFrederic Weisbecker } 57266ba94429SFrederic Weisbecker 57276ba94429SFrederic Weisbecker static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, 57286ba94429SFrederic Weisbecker const char *buf, size_t count) 57296ba94429SFrederic Weisbecker { 57306ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 57316ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 5732d4d3e257SLai Jiangshan int ret = -ENOMEM; 5733d4d3e257SLai Jiangshan 5734d4d3e257SLai Jiangshan apply_wqattrs_lock(); 57356ba94429SFrederic Weisbecker 57366ba94429SFrederic Weisbecker attrs = wq_sysfs_prep_attrs(wq); 57376ba94429SFrederic Weisbecker if (!attrs) 5738d4d3e257SLai Jiangshan goto out_unlock; 57396ba94429SFrederic Weisbecker 57406ba94429SFrederic Weisbecker if (sscanf(buf, "%d", &attrs->nice) == 1 && 57416ba94429SFrederic Weisbecker attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) 5742d4d3e257SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 57436ba94429SFrederic Weisbecker else 57446ba94429SFrederic Weisbecker ret = -EINVAL; 57456ba94429SFrederic Weisbecker 5746d4d3e257SLai Jiangshan out_unlock: 5747d4d3e257SLai Jiangshan apply_wqattrs_unlock(); 57486ba94429SFrederic Weisbecker free_workqueue_attrs(attrs); 57496ba94429SFrederic Weisbecker return ret ?: count; 57506ba94429SFrederic Weisbecker } 57516ba94429SFrederic Weisbecker 57526ba94429SFrederic Weisbecker static ssize_t wq_cpumask_show(struct device *dev, 57536ba94429SFrederic Weisbecker struct device_attribute *attr, char *buf) 57546ba94429SFrederic Weisbecker { 57556ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 57566ba94429SFrederic Weisbecker int written; 57576ba94429SFrederic Weisbecker 57586ba94429SFrederic Weisbecker mutex_lock(&wq->mutex); 57596ba94429SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%*pb\n", 57606ba94429SFrederic Weisbecker cpumask_pr_args(wq->unbound_attrs->cpumask)); 57616ba94429SFrederic Weisbecker mutex_unlock(&wq->mutex); 57626ba94429SFrederic Weisbecker return written; 57636ba94429SFrederic Weisbecker } 57646ba94429SFrederic Weisbecker 57656ba94429SFrederic Weisbecker static ssize_t wq_cpumask_store(struct device *dev, 57666ba94429SFrederic Weisbecker struct device_attribute *attr, 57676ba94429SFrederic Weisbecker const char *buf, size_t count) 57686ba94429SFrederic Weisbecker { 57696ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 57706ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 5771d4d3e257SLai Jiangshan int ret = -ENOMEM; 5772d4d3e257SLai Jiangshan 5773d4d3e257SLai Jiangshan apply_wqattrs_lock(); 57746ba94429SFrederic Weisbecker 57756ba94429SFrederic Weisbecker attrs = wq_sysfs_prep_attrs(wq); 57766ba94429SFrederic Weisbecker if (!attrs) 5777d4d3e257SLai Jiangshan goto out_unlock; 57786ba94429SFrederic Weisbecker 57796ba94429SFrederic Weisbecker ret = cpumask_parse(buf, attrs->cpumask); 57806ba94429SFrederic Weisbecker if (!ret) 5781d4d3e257SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 57826ba94429SFrederic Weisbecker 5783d4d3e257SLai Jiangshan out_unlock: 5784d4d3e257SLai Jiangshan apply_wqattrs_unlock(); 57856ba94429SFrederic Weisbecker free_workqueue_attrs(attrs); 57866ba94429SFrederic Weisbecker return ret ?: count; 57876ba94429SFrederic Weisbecker } 57886ba94429SFrederic Weisbecker 57896ba94429SFrederic Weisbecker static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, 57906ba94429SFrederic Weisbecker char *buf) 57916ba94429SFrederic Weisbecker { 57926ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 57936ba94429SFrederic Weisbecker int written; 57946ba94429SFrederic Weisbecker 57956ba94429SFrederic Weisbecker mutex_lock(&wq->mutex); 57966ba94429SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%d\n", 57976ba94429SFrederic Weisbecker !wq->unbound_attrs->no_numa); 57986ba94429SFrederic Weisbecker mutex_unlock(&wq->mutex); 57996ba94429SFrederic Weisbecker 58006ba94429SFrederic Weisbecker return written; 58016ba94429SFrederic Weisbecker } 58026ba94429SFrederic Weisbecker 58036ba94429SFrederic Weisbecker static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, 58046ba94429SFrederic Weisbecker const char *buf, size_t count) 58056ba94429SFrederic Weisbecker { 58066ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 58076ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 5808d4d3e257SLai Jiangshan int v, ret = -ENOMEM; 5809d4d3e257SLai Jiangshan 5810d4d3e257SLai Jiangshan apply_wqattrs_lock(); 58116ba94429SFrederic Weisbecker 58126ba94429SFrederic Weisbecker attrs = wq_sysfs_prep_attrs(wq); 58136ba94429SFrederic Weisbecker if (!attrs) 5814d4d3e257SLai Jiangshan goto out_unlock; 58156ba94429SFrederic Weisbecker 58166ba94429SFrederic Weisbecker ret = -EINVAL; 58176ba94429SFrederic Weisbecker if (sscanf(buf, "%d", &v) == 1) { 58186ba94429SFrederic Weisbecker attrs->no_numa = !v; 5819d4d3e257SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 58206ba94429SFrederic Weisbecker } 58216ba94429SFrederic Weisbecker 5822d4d3e257SLai Jiangshan out_unlock: 5823d4d3e257SLai Jiangshan apply_wqattrs_unlock(); 58246ba94429SFrederic Weisbecker free_workqueue_attrs(attrs); 58256ba94429SFrederic Weisbecker return ret ?: count; 58266ba94429SFrederic Weisbecker } 58276ba94429SFrederic Weisbecker 58286ba94429SFrederic Weisbecker static struct device_attribute wq_sysfs_unbound_attrs[] = { 58296ba94429SFrederic Weisbecker __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), 58306ba94429SFrederic Weisbecker __ATTR(nice, 0644, wq_nice_show, wq_nice_store), 58316ba94429SFrederic Weisbecker __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), 58326ba94429SFrederic Weisbecker __ATTR(numa, 0644, wq_numa_show, wq_numa_store), 58336ba94429SFrederic Weisbecker __ATTR_NULL, 58346ba94429SFrederic Weisbecker }; 58356ba94429SFrederic Weisbecker 58366ba94429SFrederic Weisbecker static struct bus_type wq_subsys = { 58376ba94429SFrederic Weisbecker .name = "workqueue", 58386ba94429SFrederic Weisbecker .dev_groups = wq_sysfs_groups, 58396ba94429SFrederic Weisbecker }; 58406ba94429SFrederic Weisbecker 5841b05a7928SFrederic Weisbecker static ssize_t wq_unbound_cpumask_show(struct device *dev, 5842b05a7928SFrederic Weisbecker struct device_attribute *attr, char *buf) 5843b05a7928SFrederic Weisbecker { 5844b05a7928SFrederic Weisbecker int written; 5845b05a7928SFrederic Weisbecker 5846042f7df1SLai Jiangshan mutex_lock(&wq_pool_mutex); 5847b05a7928SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%*pb\n", 5848b05a7928SFrederic Weisbecker cpumask_pr_args(wq_unbound_cpumask)); 5849042f7df1SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5850b05a7928SFrederic Weisbecker 5851b05a7928SFrederic Weisbecker return written; 5852b05a7928SFrederic Weisbecker } 5853b05a7928SFrederic Weisbecker 5854042f7df1SLai Jiangshan static ssize_t wq_unbound_cpumask_store(struct device *dev, 5855042f7df1SLai Jiangshan struct device_attribute *attr, const char *buf, size_t count) 5856042f7df1SLai Jiangshan { 5857042f7df1SLai Jiangshan cpumask_var_t cpumask; 5858042f7df1SLai Jiangshan int ret; 5859042f7df1SLai Jiangshan 5860042f7df1SLai Jiangshan if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) 5861042f7df1SLai Jiangshan return -ENOMEM; 5862042f7df1SLai Jiangshan 5863042f7df1SLai Jiangshan ret = cpumask_parse(buf, cpumask); 5864042f7df1SLai Jiangshan if (!ret) 5865042f7df1SLai Jiangshan ret = workqueue_set_unbound_cpumask(cpumask); 5866042f7df1SLai Jiangshan 5867042f7df1SLai Jiangshan free_cpumask_var(cpumask); 5868042f7df1SLai Jiangshan return ret ? ret : count; 5869042f7df1SLai Jiangshan } 5870042f7df1SLai Jiangshan 5871b05a7928SFrederic Weisbecker static struct device_attribute wq_sysfs_cpumask_attr = 5872042f7df1SLai Jiangshan __ATTR(cpumask, 0644, wq_unbound_cpumask_show, 5873042f7df1SLai Jiangshan wq_unbound_cpumask_store); 5874b05a7928SFrederic Weisbecker 58756ba94429SFrederic Weisbecker static int __init wq_sysfs_init(void) 58766ba94429SFrederic Weisbecker { 5877686f6697SGreg Kroah-Hartman struct device *dev_root; 5878b05a7928SFrederic Weisbecker int err; 5879b05a7928SFrederic Weisbecker 5880b05a7928SFrederic Weisbecker err = subsys_virtual_register(&wq_subsys, NULL); 5881b05a7928SFrederic Weisbecker if (err) 5882b05a7928SFrederic Weisbecker return err; 5883b05a7928SFrederic Weisbecker 5884686f6697SGreg Kroah-Hartman dev_root = bus_get_dev_root(&wq_subsys); 5885686f6697SGreg Kroah-Hartman if (dev_root) { 5886686f6697SGreg Kroah-Hartman err = device_create_file(dev_root, &wq_sysfs_cpumask_attr); 5887686f6697SGreg Kroah-Hartman put_device(dev_root); 5888686f6697SGreg Kroah-Hartman } 5889686f6697SGreg Kroah-Hartman return err; 58906ba94429SFrederic Weisbecker } 58916ba94429SFrederic Weisbecker core_initcall(wq_sysfs_init); 58926ba94429SFrederic Weisbecker 58936ba94429SFrederic Weisbecker static void wq_device_release(struct device *dev) 58946ba94429SFrederic Weisbecker { 58956ba94429SFrederic Weisbecker struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 58966ba94429SFrederic Weisbecker 58976ba94429SFrederic Weisbecker kfree(wq_dev); 58986ba94429SFrederic Weisbecker } 58996ba94429SFrederic Weisbecker 59006ba94429SFrederic Weisbecker /** 59016ba94429SFrederic Weisbecker * workqueue_sysfs_register - make a workqueue visible in sysfs 59026ba94429SFrederic Weisbecker * @wq: the workqueue to register 59036ba94429SFrederic Weisbecker * 59046ba94429SFrederic Weisbecker * Expose @wq in sysfs under /sys/bus/workqueue/devices. 59056ba94429SFrederic Weisbecker * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set 59066ba94429SFrederic Weisbecker * which is the preferred method. 59076ba94429SFrederic Weisbecker * 59086ba94429SFrederic Weisbecker * Workqueue user should use this function directly iff it wants to apply 59096ba94429SFrederic Weisbecker * workqueue_attrs before making the workqueue visible in sysfs; otherwise, 59106ba94429SFrederic Weisbecker * apply_workqueue_attrs() may race against userland updating the 59116ba94429SFrederic Weisbecker * attributes. 59126ba94429SFrederic Weisbecker * 59136ba94429SFrederic Weisbecker * Return: 0 on success, -errno on failure. 59146ba94429SFrederic Weisbecker */ 59156ba94429SFrederic Weisbecker int workqueue_sysfs_register(struct workqueue_struct *wq) 59166ba94429SFrederic Weisbecker { 59176ba94429SFrederic Weisbecker struct wq_device *wq_dev; 59186ba94429SFrederic Weisbecker int ret; 59196ba94429SFrederic Weisbecker 59206ba94429SFrederic Weisbecker /* 5921402dd89dSShailendra Verma * Adjusting max_active or creating new pwqs by applying 59226ba94429SFrederic Weisbecker * attributes breaks ordering guarantee. Disallow exposing ordered 59236ba94429SFrederic Weisbecker * workqueues. 59246ba94429SFrederic Weisbecker */ 59250a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 59266ba94429SFrederic Weisbecker return -EINVAL; 59276ba94429SFrederic Weisbecker 59286ba94429SFrederic Weisbecker wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); 59296ba94429SFrederic Weisbecker if (!wq_dev) 59306ba94429SFrederic Weisbecker return -ENOMEM; 59316ba94429SFrederic Weisbecker 59326ba94429SFrederic Weisbecker wq_dev->wq = wq; 59336ba94429SFrederic Weisbecker wq_dev->dev.bus = &wq_subsys; 59346ba94429SFrederic Weisbecker wq_dev->dev.release = wq_device_release; 593523217b44SLars-Peter Clausen dev_set_name(&wq_dev->dev, "%s", wq->name); 59366ba94429SFrederic Weisbecker 59376ba94429SFrederic Weisbecker /* 59386ba94429SFrederic Weisbecker * unbound_attrs are created separately. Suppress uevent until 59396ba94429SFrederic Weisbecker * everything is ready. 59406ba94429SFrederic Weisbecker */ 59416ba94429SFrederic Weisbecker dev_set_uevent_suppress(&wq_dev->dev, true); 59426ba94429SFrederic Weisbecker 59436ba94429SFrederic Weisbecker ret = device_register(&wq_dev->dev); 59446ba94429SFrederic Weisbecker if (ret) { 5945537f4146SArvind Yadav put_device(&wq_dev->dev); 59466ba94429SFrederic Weisbecker wq->wq_dev = NULL; 59476ba94429SFrederic Weisbecker return ret; 59486ba94429SFrederic Weisbecker } 59496ba94429SFrederic Weisbecker 59506ba94429SFrederic Weisbecker if (wq->flags & WQ_UNBOUND) { 59516ba94429SFrederic Weisbecker struct device_attribute *attr; 59526ba94429SFrederic Weisbecker 59536ba94429SFrederic Weisbecker for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { 59546ba94429SFrederic Weisbecker ret = device_create_file(&wq_dev->dev, attr); 59556ba94429SFrederic Weisbecker if (ret) { 59566ba94429SFrederic Weisbecker device_unregister(&wq_dev->dev); 59576ba94429SFrederic Weisbecker wq->wq_dev = NULL; 59586ba94429SFrederic Weisbecker return ret; 59596ba94429SFrederic Weisbecker } 59606ba94429SFrederic Weisbecker } 59616ba94429SFrederic Weisbecker } 59626ba94429SFrederic Weisbecker 59636ba94429SFrederic Weisbecker dev_set_uevent_suppress(&wq_dev->dev, false); 59646ba94429SFrederic Weisbecker kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); 59656ba94429SFrederic Weisbecker return 0; 59666ba94429SFrederic Weisbecker } 59676ba94429SFrederic Weisbecker 59686ba94429SFrederic Weisbecker /** 59696ba94429SFrederic Weisbecker * workqueue_sysfs_unregister - undo workqueue_sysfs_register() 59706ba94429SFrederic Weisbecker * @wq: the workqueue to unregister 59716ba94429SFrederic Weisbecker * 59726ba94429SFrederic Weisbecker * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. 59736ba94429SFrederic Weisbecker */ 59746ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq) 59756ba94429SFrederic Weisbecker { 59766ba94429SFrederic Weisbecker struct wq_device *wq_dev = wq->wq_dev; 59776ba94429SFrederic Weisbecker 59786ba94429SFrederic Weisbecker if (!wq->wq_dev) 59796ba94429SFrederic Weisbecker return; 59806ba94429SFrederic Weisbecker 59816ba94429SFrederic Weisbecker wq->wq_dev = NULL; 59826ba94429SFrederic Weisbecker device_unregister(&wq_dev->dev); 59836ba94429SFrederic Weisbecker } 59846ba94429SFrederic Weisbecker #else /* CONFIG_SYSFS */ 59856ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } 59866ba94429SFrederic Weisbecker #endif /* CONFIG_SYSFS */ 59876ba94429SFrederic Weisbecker 598882607adcSTejun Heo /* 598982607adcSTejun Heo * Workqueue watchdog. 599082607adcSTejun Heo * 599182607adcSTejun Heo * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal 599282607adcSTejun Heo * flush dependency, a concurrency managed work item which stays RUNNING 599382607adcSTejun Heo * indefinitely. Workqueue stalls can be very difficult to debug as the 599482607adcSTejun Heo * usual warning mechanisms don't trigger and internal workqueue state is 599582607adcSTejun Heo * largely opaque. 599682607adcSTejun Heo * 599782607adcSTejun Heo * Workqueue watchdog monitors all worker pools periodically and dumps 599882607adcSTejun Heo * state if some pools failed to make forward progress for a while where 599982607adcSTejun Heo * forward progress is defined as the first item on ->worklist changing. 600082607adcSTejun Heo * 600182607adcSTejun Heo * This mechanism is controlled through the kernel parameter 600282607adcSTejun Heo * "workqueue.watchdog_thresh" which can be updated at runtime through the 600382607adcSTejun Heo * corresponding sysfs parameter file. 600482607adcSTejun Heo */ 600582607adcSTejun Heo #ifdef CONFIG_WQ_WATCHDOG 600682607adcSTejun Heo 600782607adcSTejun Heo static unsigned long wq_watchdog_thresh = 30; 60085cd79d6aSKees Cook static struct timer_list wq_watchdog_timer; 600982607adcSTejun Heo 601082607adcSTejun Heo static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; 601182607adcSTejun Heo static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; 601282607adcSTejun Heo 6013cd2440d6SPetr Mladek /* 6014cd2440d6SPetr Mladek * Show workers that might prevent the processing of pending work items. 6015cd2440d6SPetr Mladek * The only candidates are CPU-bound workers in the running state. 6016cd2440d6SPetr Mladek * Pending work items should be handled by another idle worker 6017cd2440d6SPetr Mladek * in all other situations. 6018cd2440d6SPetr Mladek */ 6019cd2440d6SPetr Mladek static void show_cpu_pool_hog(struct worker_pool *pool) 6020cd2440d6SPetr Mladek { 6021cd2440d6SPetr Mladek struct worker *worker; 6022cd2440d6SPetr Mladek unsigned long flags; 6023cd2440d6SPetr Mladek int bkt; 6024cd2440d6SPetr Mladek 6025cd2440d6SPetr Mladek raw_spin_lock_irqsave(&pool->lock, flags); 6026cd2440d6SPetr Mladek 6027cd2440d6SPetr Mladek hash_for_each(pool->busy_hash, bkt, worker, hentry) { 6028cd2440d6SPetr Mladek if (task_is_running(worker->task)) { 6029cd2440d6SPetr Mladek /* 6030cd2440d6SPetr Mladek * Defer printing to avoid deadlocks in console 6031cd2440d6SPetr Mladek * drivers that queue work while holding locks 6032cd2440d6SPetr Mladek * also taken in their write paths. 6033cd2440d6SPetr Mladek */ 6034cd2440d6SPetr Mladek printk_deferred_enter(); 6035cd2440d6SPetr Mladek 6036cd2440d6SPetr Mladek pr_info("pool %d:\n", pool->id); 6037cd2440d6SPetr Mladek sched_show_task(worker->task); 6038cd2440d6SPetr Mladek 6039cd2440d6SPetr Mladek printk_deferred_exit(); 6040cd2440d6SPetr Mladek } 6041cd2440d6SPetr Mladek } 6042cd2440d6SPetr Mladek 6043cd2440d6SPetr Mladek raw_spin_unlock_irqrestore(&pool->lock, flags); 6044cd2440d6SPetr Mladek } 6045cd2440d6SPetr Mladek 6046cd2440d6SPetr Mladek static void show_cpu_pools_hogs(void) 6047cd2440d6SPetr Mladek { 6048cd2440d6SPetr Mladek struct worker_pool *pool; 6049cd2440d6SPetr Mladek int pi; 6050cd2440d6SPetr Mladek 6051cd2440d6SPetr Mladek pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n"); 6052cd2440d6SPetr Mladek 6053cd2440d6SPetr Mladek rcu_read_lock(); 6054cd2440d6SPetr Mladek 6055cd2440d6SPetr Mladek for_each_pool(pool, pi) { 6056cd2440d6SPetr Mladek if (pool->cpu_stall) 6057cd2440d6SPetr Mladek show_cpu_pool_hog(pool); 6058cd2440d6SPetr Mladek 6059cd2440d6SPetr Mladek } 6060cd2440d6SPetr Mladek 6061cd2440d6SPetr Mladek rcu_read_unlock(); 6062cd2440d6SPetr Mladek } 6063cd2440d6SPetr Mladek 606482607adcSTejun Heo static void wq_watchdog_reset_touched(void) 606582607adcSTejun Heo { 606682607adcSTejun Heo int cpu; 606782607adcSTejun Heo 606882607adcSTejun Heo wq_watchdog_touched = jiffies; 606982607adcSTejun Heo for_each_possible_cpu(cpu) 607082607adcSTejun Heo per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; 607182607adcSTejun Heo } 607282607adcSTejun Heo 60735cd79d6aSKees Cook static void wq_watchdog_timer_fn(struct timer_list *unused) 607482607adcSTejun Heo { 607582607adcSTejun Heo unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; 607682607adcSTejun Heo bool lockup_detected = false; 6077cd2440d6SPetr Mladek bool cpu_pool_stall = false; 6078940d71c6SSergey Senozhatsky unsigned long now = jiffies; 607982607adcSTejun Heo struct worker_pool *pool; 608082607adcSTejun Heo int pi; 608182607adcSTejun Heo 608282607adcSTejun Heo if (!thresh) 608382607adcSTejun Heo return; 608482607adcSTejun Heo 608582607adcSTejun Heo rcu_read_lock(); 608682607adcSTejun Heo 608782607adcSTejun Heo for_each_pool(pool, pi) { 608882607adcSTejun Heo unsigned long pool_ts, touched, ts; 608982607adcSTejun Heo 6090cd2440d6SPetr Mladek pool->cpu_stall = false; 609182607adcSTejun Heo if (list_empty(&pool->worklist)) 609282607adcSTejun Heo continue; 609382607adcSTejun Heo 6094940d71c6SSergey Senozhatsky /* 6095940d71c6SSergey Senozhatsky * If a virtual machine is stopped by the host it can look to 6096940d71c6SSergey Senozhatsky * the watchdog like a stall. 6097940d71c6SSergey Senozhatsky */ 6098940d71c6SSergey Senozhatsky kvm_check_and_clear_guest_paused(); 6099940d71c6SSergey Senozhatsky 610082607adcSTejun Heo /* get the latest of pool and touched timestamps */ 610189e28ce6SWang Qing if (pool->cpu >= 0) 610289e28ce6SWang Qing touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu)); 610389e28ce6SWang Qing else 610482607adcSTejun Heo touched = READ_ONCE(wq_watchdog_touched); 610589e28ce6SWang Qing pool_ts = READ_ONCE(pool->watchdog_ts); 610682607adcSTejun Heo 610782607adcSTejun Heo if (time_after(pool_ts, touched)) 610882607adcSTejun Heo ts = pool_ts; 610982607adcSTejun Heo else 611082607adcSTejun Heo ts = touched; 611182607adcSTejun Heo 611282607adcSTejun Heo /* did we stall? */ 6113940d71c6SSergey Senozhatsky if (time_after(now, ts + thresh)) { 611482607adcSTejun Heo lockup_detected = true; 6115cd2440d6SPetr Mladek if (pool->cpu >= 0) { 6116cd2440d6SPetr Mladek pool->cpu_stall = true; 6117cd2440d6SPetr Mladek cpu_pool_stall = true; 6118cd2440d6SPetr Mladek } 611982607adcSTejun Heo pr_emerg("BUG: workqueue lockup - pool"); 612082607adcSTejun Heo pr_cont_pool_info(pool); 612182607adcSTejun Heo pr_cont(" stuck for %us!\n", 6122940d71c6SSergey Senozhatsky jiffies_to_msecs(now - pool_ts) / 1000); 612382607adcSTejun Heo } 6124cd2440d6SPetr Mladek 6125cd2440d6SPetr Mladek 612682607adcSTejun Heo } 612782607adcSTejun Heo 612882607adcSTejun Heo rcu_read_unlock(); 612982607adcSTejun Heo 613082607adcSTejun Heo if (lockup_detected) 613155df0933SImran Khan show_all_workqueues(); 613282607adcSTejun Heo 6133cd2440d6SPetr Mladek if (cpu_pool_stall) 6134cd2440d6SPetr Mladek show_cpu_pools_hogs(); 6135cd2440d6SPetr Mladek 613682607adcSTejun Heo wq_watchdog_reset_touched(); 613782607adcSTejun Heo mod_timer(&wq_watchdog_timer, jiffies + thresh); 613882607adcSTejun Heo } 613982607adcSTejun Heo 6140cb9d7fd5SVincent Whitchurch notrace void wq_watchdog_touch(int cpu) 614182607adcSTejun Heo { 614282607adcSTejun Heo if (cpu >= 0) 614382607adcSTejun Heo per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; 614489e28ce6SWang Qing 614582607adcSTejun Heo wq_watchdog_touched = jiffies; 614682607adcSTejun Heo } 614782607adcSTejun Heo 614882607adcSTejun Heo static void wq_watchdog_set_thresh(unsigned long thresh) 614982607adcSTejun Heo { 615082607adcSTejun Heo wq_watchdog_thresh = 0; 615182607adcSTejun Heo del_timer_sync(&wq_watchdog_timer); 615282607adcSTejun Heo 615382607adcSTejun Heo if (thresh) { 615482607adcSTejun Heo wq_watchdog_thresh = thresh; 615582607adcSTejun Heo wq_watchdog_reset_touched(); 615682607adcSTejun Heo mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ); 615782607adcSTejun Heo } 615882607adcSTejun Heo } 615982607adcSTejun Heo 616082607adcSTejun Heo static int wq_watchdog_param_set_thresh(const char *val, 616182607adcSTejun Heo const struct kernel_param *kp) 616282607adcSTejun Heo { 616382607adcSTejun Heo unsigned long thresh; 616482607adcSTejun Heo int ret; 616582607adcSTejun Heo 616682607adcSTejun Heo ret = kstrtoul(val, 0, &thresh); 616782607adcSTejun Heo if (ret) 616882607adcSTejun Heo return ret; 616982607adcSTejun Heo 617082607adcSTejun Heo if (system_wq) 617182607adcSTejun Heo wq_watchdog_set_thresh(thresh); 617282607adcSTejun Heo else 617382607adcSTejun Heo wq_watchdog_thresh = thresh; 617482607adcSTejun Heo 617582607adcSTejun Heo return 0; 617682607adcSTejun Heo } 617782607adcSTejun Heo 617882607adcSTejun Heo static const struct kernel_param_ops wq_watchdog_thresh_ops = { 617982607adcSTejun Heo .set = wq_watchdog_param_set_thresh, 618082607adcSTejun Heo .get = param_get_ulong, 618182607adcSTejun Heo }; 618282607adcSTejun Heo 618382607adcSTejun Heo module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, 618482607adcSTejun Heo 0644); 618582607adcSTejun Heo 618682607adcSTejun Heo static void wq_watchdog_init(void) 618782607adcSTejun Heo { 61885cd79d6aSKees Cook timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE); 618982607adcSTejun Heo wq_watchdog_set_thresh(wq_watchdog_thresh); 619082607adcSTejun Heo } 619182607adcSTejun Heo 619282607adcSTejun Heo #else /* CONFIG_WQ_WATCHDOG */ 619382607adcSTejun Heo 619482607adcSTejun Heo static inline void wq_watchdog_init(void) { } 619582607adcSTejun Heo 619682607adcSTejun Heo #endif /* CONFIG_WQ_WATCHDOG */ 619782607adcSTejun Heo 6198bce90380STejun Heo static void __init wq_numa_init(void) 6199bce90380STejun Heo { 6200bce90380STejun Heo cpumask_var_t *tbl; 6201bce90380STejun Heo int node, cpu; 6202bce90380STejun Heo 6203bce90380STejun Heo if (num_possible_nodes() <= 1) 6204bce90380STejun Heo return; 6205bce90380STejun Heo 6206d55262c4STejun Heo if (wq_disable_numa) { 6207d55262c4STejun Heo pr_info("workqueue: NUMA affinity support disabled\n"); 6208d55262c4STejun Heo return; 6209d55262c4STejun Heo } 6210d55262c4STejun Heo 6211f728c4a9SZhen Lei for_each_possible_cpu(cpu) { 6212f728c4a9SZhen Lei if (WARN_ON(cpu_to_node(cpu) == NUMA_NO_NODE)) { 6213f728c4a9SZhen Lei pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); 6214f728c4a9SZhen Lei return; 6215f728c4a9SZhen Lei } 6216f728c4a9SZhen Lei } 6217f728c4a9SZhen Lei 6218be69d00dSThomas Gleixner wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(); 62194c16bd32STejun Heo BUG_ON(!wq_update_unbound_numa_attrs_buf); 62204c16bd32STejun Heo 6221bce90380STejun Heo /* 6222bce90380STejun Heo * We want masks of possible CPUs of each node which isn't readily 6223bce90380STejun Heo * available. Build one from cpu_to_node() which should have been 6224bce90380STejun Heo * fully initialized by now. 6225bce90380STejun Heo */ 62266396bb22SKees Cook tbl = kcalloc(nr_node_ids, sizeof(tbl[0]), GFP_KERNEL); 6227bce90380STejun Heo BUG_ON(!tbl); 6228bce90380STejun Heo 6229bce90380STejun Heo for_each_node(node) 62305a6024f1SYasuaki Ishimatsu BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL, 62311be0c25dSTejun Heo node_online(node) ? node : NUMA_NO_NODE)); 6232bce90380STejun Heo 6233bce90380STejun Heo for_each_possible_cpu(cpu) { 6234bce90380STejun Heo node = cpu_to_node(cpu); 6235bce90380STejun Heo cpumask_set_cpu(cpu, tbl[node]); 6236bce90380STejun Heo } 6237bce90380STejun Heo 6238bce90380STejun Heo wq_numa_possible_cpumask = tbl; 6239bce90380STejun Heo wq_numa_enabled = true; 6240bce90380STejun Heo } 6241bce90380STejun Heo 62423347fa09STejun Heo /** 62433347fa09STejun Heo * workqueue_init_early - early init for workqueue subsystem 62443347fa09STejun Heo * 62453347fa09STejun Heo * This is the first half of two-staged workqueue subsystem initialization 62463347fa09STejun Heo * and invoked as soon as the bare basics - memory allocation, cpumasks and 62473347fa09STejun Heo * idr are up. It sets up all the data structures and system workqueues 62483347fa09STejun Heo * and allows early boot code to create workqueues and queue/cancel work 62493347fa09STejun Heo * items. Actual work item execution starts only after kthreads can be 62503347fa09STejun Heo * created and scheduled right before early initcalls. 62513347fa09STejun Heo */ 62522333e829SYu Chen void __init workqueue_init_early(void) 62531da177e4SLinus Torvalds { 62547a4e344cSTejun Heo int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; 62557a4e344cSTejun Heo int i, cpu; 6256c34056a3STejun Heo 625710cdb157SLai Jiangshan BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); 6258e904e6c2STejun Heo 6259b05a7928SFrederic Weisbecker BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); 626004d4e665SFrederic Weisbecker cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(HK_TYPE_WQ)); 626104d4e665SFrederic Weisbecker cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, housekeeping_cpumask(HK_TYPE_DOMAIN)); 6262b05a7928SFrederic Weisbecker 6263e904e6c2STejun Heo pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); 6264e904e6c2STejun Heo 6265706026c2STejun Heo /* initialize CPU pools */ 626629c91e99STejun Heo for_each_possible_cpu(cpu) { 62674ce62e9eSTejun Heo struct worker_pool *pool; 62688b03ae3cSTejun Heo 62697a4e344cSTejun Heo i = 0; 6270f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 62717a4e344cSTejun Heo BUG_ON(init_worker_pool(pool)); 6272ec22ca5eSTejun Heo pool->cpu = cpu; 62737a4e344cSTejun Heo cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); 62747a4e344cSTejun Heo pool->attrs->nice = std_nice[i++]; 6275f3f90ad4STejun Heo pool->node = cpu_to_node(cpu); 62767a4e344cSTejun Heo 62779daf9e67STejun Heo /* alloc pool ID */ 627868e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 62799daf9e67STejun Heo BUG_ON(worker_pool_assign_id(pool)); 628068e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 62814ce62e9eSTejun Heo } 62828b03ae3cSTejun Heo } 62838b03ae3cSTejun Heo 62848a2b7538STejun Heo /* create default unbound and ordered wq attrs */ 628529c91e99STejun Heo for (i = 0; i < NR_STD_WORKER_POOLS; i++) { 628629c91e99STejun Heo struct workqueue_attrs *attrs; 628729c91e99STejun Heo 6288be69d00dSThomas Gleixner BUG_ON(!(attrs = alloc_workqueue_attrs())); 628929c91e99STejun Heo attrs->nice = std_nice[i]; 629029c91e99STejun Heo unbound_std_wq_attrs[i] = attrs; 62918a2b7538STejun Heo 62928a2b7538STejun Heo /* 62938a2b7538STejun Heo * An ordered wq should have only one pwq as ordering is 62948a2b7538STejun Heo * guaranteed by max_active which is enforced by pwqs. 62958a2b7538STejun Heo * Turn off NUMA so that dfl_pwq is used for all nodes. 62968a2b7538STejun Heo */ 6297be69d00dSThomas Gleixner BUG_ON(!(attrs = alloc_workqueue_attrs())); 62988a2b7538STejun Heo attrs->nice = std_nice[i]; 62998a2b7538STejun Heo attrs->no_numa = true; 63008a2b7538STejun Heo ordered_wq_attrs[i] = attrs; 630129c91e99STejun Heo } 630229c91e99STejun Heo 6303d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 63041aabe902SJoonsoo Kim system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 6305d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 6306f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 6307f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 630824d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 630924d51addSTejun Heo WQ_FREEZABLE, 0); 63100668106cSViresh Kumar system_power_efficient_wq = alloc_workqueue("events_power_efficient", 63110668106cSViresh Kumar WQ_POWER_EFFICIENT, 0); 63120668106cSViresh Kumar system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", 63130668106cSViresh Kumar WQ_FREEZABLE | WQ_POWER_EFFICIENT, 63140668106cSViresh Kumar 0); 63151aabe902SJoonsoo Kim BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 63160668106cSViresh Kumar !system_unbound_wq || !system_freezable_wq || 63170668106cSViresh Kumar !system_power_efficient_wq || 63180668106cSViresh Kumar !system_freezable_power_efficient_wq); 63193347fa09STejun Heo } 63203347fa09STejun Heo 63213347fa09STejun Heo /** 63223347fa09STejun Heo * workqueue_init - bring workqueue subsystem fully online 63233347fa09STejun Heo * 63243347fa09STejun Heo * This is the latter half of two-staged workqueue subsystem initialization 63253347fa09STejun Heo * and invoked as soon as kthreads can be created and scheduled. 63263347fa09STejun Heo * Workqueues have been created and work items queued on them, but there 63273347fa09STejun Heo * are no kworkers executing the work items yet. Populate the worker pools 63283347fa09STejun Heo * with the initial workers and enable future kworker creations. 63293347fa09STejun Heo */ 63302333e829SYu Chen void __init workqueue_init(void) 63313347fa09STejun Heo { 63322186d9f9STejun Heo struct workqueue_struct *wq; 63333347fa09STejun Heo struct worker_pool *pool; 63343347fa09STejun Heo int cpu, bkt; 63353347fa09STejun Heo 63362186d9f9STejun Heo /* 63372186d9f9STejun Heo * It'd be simpler to initialize NUMA in workqueue_init_early() but 63382186d9f9STejun Heo * CPU to node mapping may not be available that early on some 63392186d9f9STejun Heo * archs such as power and arm64. As per-cpu pools created 63402186d9f9STejun Heo * previously could be missing node hint and unbound pools NUMA 63412186d9f9STejun Heo * affinity, fix them up. 634240c17f75STejun Heo * 634340c17f75STejun Heo * Also, while iterating workqueues, create rescuers if requested. 63442186d9f9STejun Heo */ 63452186d9f9STejun Heo wq_numa_init(); 63462186d9f9STejun Heo 63472186d9f9STejun Heo mutex_lock(&wq_pool_mutex); 63482186d9f9STejun Heo 63492186d9f9STejun Heo for_each_possible_cpu(cpu) { 63502186d9f9STejun Heo for_each_cpu_worker_pool(pool, cpu) { 63512186d9f9STejun Heo pool->node = cpu_to_node(cpu); 63522186d9f9STejun Heo } 63532186d9f9STejun Heo } 63542186d9f9STejun Heo 635540c17f75STejun Heo list_for_each_entry(wq, &workqueues, list) { 63562186d9f9STejun Heo wq_update_unbound_numa(wq, smp_processor_id(), true); 635740c17f75STejun Heo WARN(init_rescuer(wq), 635840c17f75STejun Heo "workqueue: failed to create early rescuer for %s", 635940c17f75STejun Heo wq->name); 636040c17f75STejun Heo } 63612186d9f9STejun Heo 63622186d9f9STejun Heo mutex_unlock(&wq_pool_mutex); 63632186d9f9STejun Heo 63643347fa09STejun Heo /* create the initial workers */ 63653347fa09STejun Heo for_each_online_cpu(cpu) { 63663347fa09STejun Heo for_each_cpu_worker_pool(pool, cpu) { 63673347fa09STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 63683347fa09STejun Heo BUG_ON(!create_worker(pool)); 63693347fa09STejun Heo } 63703347fa09STejun Heo } 63713347fa09STejun Heo 63723347fa09STejun Heo hash_for_each(unbound_pool_hash, bkt, pool, hash_node) 63733347fa09STejun Heo BUG_ON(!create_worker(pool)); 63743347fa09STejun Heo 63753347fa09STejun Heo wq_online = true; 637682607adcSTejun Heo wq_watchdog_init(); 63771da177e4SLinus Torvalds } 6378c4f135d6STetsuo Handa 6379c4f135d6STetsuo Handa /* 6380c4f135d6STetsuo Handa * Despite the naming, this is a no-op function which is here only for avoiding 6381c4f135d6STetsuo Handa * link error. Since compile-time warning may fail to catch, we will need to 6382c4f135d6STetsuo Handa * emit run-time warning from __flush_workqueue(). 6383c4f135d6STetsuo Handa */ 6384c4f135d6STetsuo Handa void __warn_flushing_systemwide_wq(void) { } 6385c4f135d6STetsuo Handa EXPORT_SYMBOL(__warn_flushing_systemwide_wq); 6386