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> 5262635ea8SSergey Senozhatsky #include <linux/nmi.h> 53e22bee78STejun Heo 54ea138446STejun Heo #include "workqueue_internal.h" 551da177e4SLinus Torvalds 56c8e55f36STejun Heo enum { 57bc2ae0f5STejun Heo /* 5824647570STejun Heo * worker_pool flags 59bc2ae0f5STejun Heo * 6024647570STejun Heo * A bound pool is either associated or disassociated with its CPU. 61bc2ae0f5STejun Heo * While associated (!DISASSOCIATED), all workers are bound to the 62bc2ae0f5STejun Heo * CPU and none has %WORKER_UNBOUND set and concurrency management 63bc2ae0f5STejun Heo * is in effect. 64bc2ae0f5STejun Heo * 65bc2ae0f5STejun Heo * While DISASSOCIATED, the cpu may be offline and all workers have 66bc2ae0f5STejun Heo * %WORKER_UNBOUND set and concurrency management disabled, and may 6724647570STejun Heo * be executing on any CPU. The pool behaves as an unbound one. 68bc2ae0f5STejun Heo * 69bc3a1afcSTejun Heo * Note that DISASSOCIATED should be flipped only while holding 701258fae7STejun Heo * wq_pool_attach_mutex to avoid changing binding state while 714736cbf7SLai Jiangshan * worker_attach_to_pool() is in progress. 72bc2ae0f5STejun Heo */ 73692b4825STejun Heo POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */ 7424647570STejun Heo POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 75db7bccf4STejun Heo 76c8e55f36STejun Heo /* worker flags */ 77c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 78c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 79e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 80fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 81f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 82a9ab775bSTejun Heo WORKER_REBOUND = 1 << 8, /* worker was rebound */ 83e22bee78STejun Heo 84a9ab775bSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | 85a9ab775bSTejun Heo WORKER_UNBOUND | WORKER_REBOUND, 86db7bccf4STejun Heo 87e34cdddbSTejun Heo NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ 884ce62e9eSTejun Heo 8929c91e99STejun Heo UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ 90c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 91db7bccf4STejun Heo 92e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 93e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 94e22bee78STejun Heo 953233cdbdSTejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, 963233cdbdSTejun Heo /* call for help after 10ms 973233cdbdSTejun Heo (min two ticks) */ 98e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 99e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 1001da177e4SLinus Torvalds 1011da177e4SLinus Torvalds /* 102e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 1038698a745SDongsheng Yang * all cpus. Give MIN_NICE. 104e22bee78STejun Heo */ 1058698a745SDongsheng Yang RESCUER_NICE_LEVEL = MIN_NICE, 1068698a745SDongsheng Yang HIGHPRI_NICE_LEVEL = MIN_NICE, 107ecf6881fSTejun Heo 108ecf6881fSTejun Heo WQ_NAME_LEN = 24, 109c8e55f36STejun Heo }; 110c8e55f36STejun Heo 1111da177e4SLinus Torvalds /* 1124690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 1134690c4abSTejun Heo * 114e41e704bSTejun Heo * I: Modifiable by initialization/destruction paths and read-only for 115e41e704bSTejun Heo * everyone else. 1164690c4abSTejun Heo * 117e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 118e22bee78STejun Heo * only be modified and accessed from the local cpu. 119e22bee78STejun Heo * 120d565ed63STejun Heo * L: pool->lock protected. Access with pool->lock held. 1214690c4abSTejun Heo * 122d565ed63STejun Heo * X: During normal operation, modification requires pool->lock and should 123d565ed63STejun Heo * be done only from local cpu. Either disabling preemption on local 124d565ed63STejun Heo * cpu or grabbing pool->lock is enough for read access. If 125d565ed63STejun Heo * POOL_DISASSOCIATED is set, it's identical to L. 126e22bee78STejun Heo * 1271258fae7STejun Heo * A: wq_pool_attach_mutex protected. 128822d8405STejun Heo * 12968e13a67SLai Jiangshan * PL: wq_pool_mutex protected. 13076af4d93STejun Heo * 13124acfb71SThomas Gleixner * PR: wq_pool_mutex protected for writes. RCU protected for reads. 1325bcab335STejun Heo * 1335b95e1afSLai Jiangshan * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads. 1345b95e1afSLai Jiangshan * 1355b95e1afSLai Jiangshan * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or 13624acfb71SThomas Gleixner * RCU for reads. 1375b95e1afSLai Jiangshan * 1383c25a55dSLai Jiangshan * WQ: wq->mutex protected. 1393c25a55dSLai Jiangshan * 14024acfb71SThomas Gleixner * WR: wq->mutex protected for writes. RCU protected for reads. 1412e109a28STejun Heo * 1422e109a28STejun Heo * MD: wq_mayday_lock protected. 1434690c4abSTejun Heo */ 1444690c4abSTejun Heo 1452eaebdb3STejun Heo /* struct worker is defined in workqueue_internal.h */ 146c34056a3STejun Heo 147bd7bdd43STejun Heo struct worker_pool { 148d565ed63STejun Heo spinlock_t lock; /* the pool lock */ 149d84ff051STejun Heo int cpu; /* I: the associated cpu */ 150f3f90ad4STejun Heo int node; /* I: the associated node ID */ 1519daf9e67STejun Heo int id; /* I: pool ID */ 15211ebea50STejun Heo unsigned int flags; /* X: flags */ 153bd7bdd43STejun Heo 15482607adcSTejun Heo unsigned long watchdog_ts; /* L: watchdog timestamp */ 15582607adcSTejun Heo 156bd7bdd43STejun Heo struct list_head worklist; /* L: list of pending works */ 157ea1abd61SLai Jiangshan 1585826cc8fSLai Jiangshan int nr_workers; /* L: total number of workers */ 1595826cc8fSLai Jiangshan int nr_idle; /* L: currently idle workers */ 160bd7bdd43STejun Heo 161bd7bdd43STejun Heo struct list_head idle_list; /* X: list of idle workers */ 162bd7bdd43STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 163bd7bdd43STejun Heo struct timer_list mayday_timer; /* L: SOS timer for workers */ 164bd7bdd43STejun Heo 165c5aa87bbSTejun Heo /* a workers is either on busy_hash or idle_list, or the manager */ 166c9e7cf27STejun Heo DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); 167c9e7cf27STejun Heo /* L: hash of busy workers */ 168c9e7cf27STejun Heo 1692607d7a6STejun Heo struct worker *manager; /* L: purely informational */ 17092f9c5c4SLai Jiangshan struct list_head workers; /* A: attached workers */ 17160f5a4bcSLai Jiangshan struct completion *detach_completion; /* all workers detached */ 172e19e397aSTejun Heo 1737cda9aaeSLai Jiangshan struct ida worker_ida; /* worker IDs for task name */ 174e19e397aSTejun Heo 1757a4e344cSTejun Heo struct workqueue_attrs *attrs; /* I: worker attributes */ 17668e13a67SLai Jiangshan struct hlist_node hash_node; /* PL: unbound_pool_hash node */ 17768e13a67SLai Jiangshan int refcnt; /* PL: refcnt for unbound pools */ 1787a4e344cSTejun Heo 179e19e397aSTejun Heo /* 180e19e397aSTejun Heo * The current concurrency level. As it's likely to be accessed 181e19e397aSTejun Heo * from other CPUs during try_to_wake_up(), put it in a separate 182e19e397aSTejun Heo * cacheline. 183e19e397aSTejun Heo */ 184e19e397aSTejun Heo atomic_t nr_running ____cacheline_aligned_in_smp; 18529c91e99STejun Heo 18629c91e99STejun Heo /* 18724acfb71SThomas Gleixner * Destruction of pool is RCU protected to allow dereferences 18829c91e99STejun Heo * from get_work_pool(). 18929c91e99STejun Heo */ 19029c91e99STejun Heo struct rcu_head rcu; 1918b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1928b03ae3cSTejun Heo 1938b03ae3cSTejun Heo /* 194112202d9STejun Heo * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS 195112202d9STejun Heo * of work_struct->data are used for flags and the remaining high bits 196112202d9STejun Heo * point to the pwq; thus, pwqs need to be aligned at two's power of the 197112202d9STejun Heo * number of flag bits. 1981da177e4SLinus Torvalds */ 199112202d9STejun Heo struct pool_workqueue { 200bd7bdd43STejun Heo struct worker_pool *pool; /* I: the associated pool */ 2014690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 20273f53c4aSTejun Heo int work_color; /* L: current color */ 20373f53c4aSTejun Heo int flush_color; /* L: flushing color */ 2048864b4e5STejun Heo int refcnt; /* L: reference count */ 20573f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 20673f53c4aSTejun Heo /* L: nr of in_flight works */ 2071e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 208a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 2091e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 2103c25a55dSLai Jiangshan struct list_head pwqs_node; /* WR: node on wq->pwqs */ 2112e109a28STejun Heo struct list_head mayday_node; /* MD: node on wq->maydays */ 2128864b4e5STejun Heo 2138864b4e5STejun Heo /* 2148864b4e5STejun Heo * Release of unbound pwq is punted to system_wq. See put_pwq() 2158864b4e5STejun Heo * and pwq_unbound_release_workfn() for details. pool_workqueue 21624acfb71SThomas Gleixner * itself is also RCU protected so that the first pwq can be 217b09f4fd3SLai Jiangshan * determined without grabbing wq->mutex. 2188864b4e5STejun Heo */ 2198864b4e5STejun Heo struct work_struct unbound_release_work; 2208864b4e5STejun Heo struct rcu_head rcu; 221e904e6c2STejun Heo } __aligned(1 << WORK_STRUCT_FLAG_BITS); 2221da177e4SLinus Torvalds 2231da177e4SLinus Torvalds /* 22473f53c4aSTejun Heo * Structure used to wait for workqueue flush. 22573f53c4aSTejun Heo */ 22673f53c4aSTejun Heo struct wq_flusher { 2273c25a55dSLai Jiangshan struct list_head list; /* WQ: list of flushers */ 2283c25a55dSLai Jiangshan int flush_color; /* WQ: flush color waiting for */ 22973f53c4aSTejun Heo struct completion done; /* flush completion */ 23073f53c4aSTejun Heo }; 2311da177e4SLinus Torvalds 232226223abSTejun Heo struct wq_device; 233226223abSTejun Heo 23473f53c4aSTejun Heo /* 235c5aa87bbSTejun Heo * The externally visible workqueue. It relays the issued work items to 236c5aa87bbSTejun Heo * the appropriate worker_pool through its pool_workqueues. 2371da177e4SLinus Torvalds */ 2381da177e4SLinus Torvalds struct workqueue_struct { 2393c25a55dSLai Jiangshan struct list_head pwqs; /* WR: all pwqs of this wq */ 240e2dca7adSTejun Heo struct list_head list; /* PR: list of all workqueues */ 24173f53c4aSTejun Heo 2423c25a55dSLai Jiangshan struct mutex mutex; /* protects this wq */ 2433c25a55dSLai Jiangshan int work_color; /* WQ: current work color */ 2443c25a55dSLai Jiangshan int flush_color; /* WQ: current flush color */ 245112202d9STejun Heo atomic_t nr_pwqs_to_flush; /* flush in progress */ 2463c25a55dSLai Jiangshan struct wq_flusher *first_flusher; /* WQ: first flusher */ 2473c25a55dSLai Jiangshan struct list_head flusher_queue; /* WQ: flush waiters */ 2483c25a55dSLai Jiangshan struct list_head flusher_overflow; /* WQ: flush overflow list */ 24973f53c4aSTejun Heo 2502e109a28STejun Heo struct list_head maydays; /* MD: pwqs requesting rescue */ 25130ae2fc0STejun Heo struct worker *rescuer; /* MD: rescue worker */ 252e22bee78STejun Heo 25387fc741eSLai Jiangshan int nr_drainers; /* WQ: drain in progress */ 254a357fc03SLai Jiangshan int saved_max_active; /* WQ: saved pwq max_active */ 255226223abSTejun Heo 2565b95e1afSLai Jiangshan struct workqueue_attrs *unbound_attrs; /* PW: only for unbound wqs */ 2575b95e1afSLai Jiangshan struct pool_workqueue *dfl_pwq; /* PW: only for unbound wqs */ 2586029a918STejun Heo 259226223abSTejun Heo #ifdef CONFIG_SYSFS 260226223abSTejun Heo struct wq_device *wq_dev; /* I: for sysfs interface */ 261226223abSTejun Heo #endif 2624e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 263669de8bdSBart Van Assche char *lock_name; 264669de8bdSBart Van Assche struct lock_class_key key; 2654e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2664e6045f1SJohannes Berg #endif 267ecf6881fSTejun Heo char name[WQ_NAME_LEN]; /* I: workqueue name */ 2682728fd2fSTejun Heo 269e2dca7adSTejun Heo /* 27024acfb71SThomas Gleixner * Destruction of workqueue_struct is RCU protected to allow walking 27124acfb71SThomas Gleixner * the workqueues list without grabbing wq_pool_mutex. 272e2dca7adSTejun Heo * This is used to dump all workqueues from sysrq. 273e2dca7adSTejun Heo */ 274e2dca7adSTejun Heo struct rcu_head rcu; 275e2dca7adSTejun Heo 2762728fd2fSTejun Heo /* hot fields used during command issue, aligned to cacheline */ 2772728fd2fSTejun Heo unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ 2782728fd2fSTejun Heo struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ 2795b95e1afSLai Jiangshan struct pool_workqueue __rcu *numa_pwq_tbl[]; /* PWR: unbound pwqs indexed by node */ 2801da177e4SLinus Torvalds }; 2811da177e4SLinus Torvalds 282e904e6c2STejun Heo static struct kmem_cache *pwq_cache; 283e904e6c2STejun Heo 284bce90380STejun Heo static cpumask_var_t *wq_numa_possible_cpumask; 285bce90380STejun Heo /* possible CPUs of each node */ 286bce90380STejun Heo 287d55262c4STejun Heo static bool wq_disable_numa; 288d55262c4STejun Heo module_param_named(disable_numa, wq_disable_numa, bool, 0444); 289d55262c4STejun Heo 290cee22a15SViresh Kumar /* see the comment above the definition of WQ_POWER_EFFICIENT */ 291552f530cSLuis R. Rodriguez static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); 292cee22a15SViresh Kumar module_param_named(power_efficient, wq_power_efficient, bool, 0444); 293cee22a15SViresh Kumar 294863b710bSTejun Heo static bool wq_online; /* can kworkers be created yet? */ 2953347fa09STejun Heo 296bce90380STejun Heo static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ 297bce90380STejun Heo 2984c16bd32STejun Heo /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ 2994c16bd32STejun Heo static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; 3004c16bd32STejun Heo 30168e13a67SLai Jiangshan static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ 3021258fae7STejun Heo static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */ 3032e109a28STejun Heo static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ 304692b4825STejun Heo static DECLARE_WAIT_QUEUE_HEAD(wq_manager_wait); /* wait for manager to go away */ 3055bcab335STejun Heo 306e2dca7adSTejun Heo static LIST_HEAD(workqueues); /* PR: list of all workqueues */ 30768e13a67SLai Jiangshan static bool workqueue_freezing; /* PL: have wqs started freezing? */ 3087d19c5ceSTejun Heo 309ef557180SMike Galbraith /* PL: allowable cpus for unbound wqs and work items */ 310ef557180SMike Galbraith static cpumask_var_t wq_unbound_cpumask; 311ef557180SMike Galbraith 312ef557180SMike Galbraith /* CPU where unbound work was last round robin scheduled from this CPU */ 313ef557180SMike Galbraith static DEFINE_PER_CPU(int, wq_rr_cpu_last); 314b05a7928SFrederic Weisbecker 315f303fccbSTejun Heo /* 316f303fccbSTejun Heo * Local execution of unbound work items is no longer guaranteed. The 317f303fccbSTejun Heo * following always forces round-robin CPU selection on unbound work items 318f303fccbSTejun Heo * to uncover usages which depend on it. 319f303fccbSTejun Heo */ 320f303fccbSTejun Heo #ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU 321f303fccbSTejun Heo static bool wq_debug_force_rr_cpu = true; 322f303fccbSTejun Heo #else 323f303fccbSTejun Heo static bool wq_debug_force_rr_cpu = false; 324f303fccbSTejun Heo #endif 325f303fccbSTejun Heo module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644); 326f303fccbSTejun Heo 3277d19c5ceSTejun Heo /* the per-cpu worker pools */ 32825528213SPeter Zijlstra static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools); 3297d19c5ceSTejun Heo 33068e13a67SLai Jiangshan static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ 3317d19c5ceSTejun Heo 33268e13a67SLai Jiangshan /* PL: hash of all unbound pools keyed by pool->attrs */ 33329c91e99STejun Heo static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); 33429c91e99STejun Heo 335c5aa87bbSTejun Heo /* I: attributes used when instantiating standard unbound pools on demand */ 33629c91e99STejun Heo static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; 33729c91e99STejun Heo 3388a2b7538STejun Heo /* I: attributes used when instantiating ordered pools on demand */ 3398a2b7538STejun Heo static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; 3408a2b7538STejun Heo 341d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 342ad7b1f84SMarc Dionne EXPORT_SYMBOL(system_wq); 343044c782cSValentin Ilie struct workqueue_struct *system_highpri_wq __read_mostly; 3441aabe902SJoonsoo Kim EXPORT_SYMBOL_GPL(system_highpri_wq); 345044c782cSValentin Ilie struct workqueue_struct *system_long_wq __read_mostly; 346d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 347044c782cSValentin Ilie struct workqueue_struct *system_unbound_wq __read_mostly; 348f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 349044c782cSValentin Ilie struct workqueue_struct *system_freezable_wq __read_mostly; 35024d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 3510668106cSViresh Kumar struct workqueue_struct *system_power_efficient_wq __read_mostly; 3520668106cSViresh Kumar EXPORT_SYMBOL_GPL(system_power_efficient_wq); 3530668106cSViresh Kumar struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; 3540668106cSViresh Kumar EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); 355d320c038STejun Heo 3567d19c5ceSTejun Heo static int worker_thread(void *__worker); 3576ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq); 358c29eb853STejun Heo static void show_pwq(struct pool_workqueue *pwq); 3597d19c5ceSTejun Heo 36097bd2347STejun Heo #define CREATE_TRACE_POINTS 36197bd2347STejun Heo #include <trace/events/workqueue.h> 36297bd2347STejun Heo 36368e13a67SLai Jiangshan #define assert_rcu_or_pool_mutex() \ 36424acfb71SThomas Gleixner RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ 365f78f5b90SPaul E. McKenney !lockdep_is_held(&wq_pool_mutex), \ 36624acfb71SThomas Gleixner "RCU or wq_pool_mutex should be held") 3675bcab335STejun Heo 368b09f4fd3SLai Jiangshan #define assert_rcu_or_wq_mutex(wq) \ 36924acfb71SThomas Gleixner RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ 370f78f5b90SPaul E. McKenney !lockdep_is_held(&wq->mutex), \ 37124acfb71SThomas Gleixner "RCU or wq->mutex should be held") 37276af4d93STejun Heo 3735b95e1afSLai Jiangshan #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \ 37424acfb71SThomas Gleixner RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ 375f78f5b90SPaul E. McKenney !lockdep_is_held(&wq->mutex) && \ 376f78f5b90SPaul E. McKenney !lockdep_is_held(&wq_pool_mutex), \ 37724acfb71SThomas Gleixner "RCU, wq->mutex or wq_pool_mutex should be held") 3785b95e1afSLai Jiangshan 379f02ae73aSTejun Heo #define for_each_cpu_worker_pool(pool, cpu) \ 380f02ae73aSTejun Heo for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ 381f02ae73aSTejun Heo (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ 3827a62c2c8STejun Heo (pool)++) 3834ce62e9eSTejun Heo 38449e3cf44STejun Heo /** 38517116969STejun Heo * for_each_pool - iterate through all worker_pools in the system 38617116969STejun Heo * @pool: iteration cursor 387611c92a0STejun Heo * @pi: integer used for iteration 388fa1b54e6STejun Heo * 38924acfb71SThomas Gleixner * This must be called either with wq_pool_mutex held or RCU read 39068e13a67SLai Jiangshan * locked. If the pool needs to be used beyond the locking in effect, the 39168e13a67SLai Jiangshan * caller is responsible for guaranteeing that the pool stays online. 392fa1b54e6STejun Heo * 393fa1b54e6STejun Heo * The if/else clause exists only for the lockdep assertion and can be 394fa1b54e6STejun Heo * ignored. 39517116969STejun Heo */ 396611c92a0STejun Heo #define for_each_pool(pool, pi) \ 397611c92a0STejun Heo idr_for_each_entry(&worker_pool_idr, pool, pi) \ 39868e13a67SLai Jiangshan if (({ assert_rcu_or_pool_mutex(); false; })) { } \ 399fa1b54e6STejun Heo else 40017116969STejun Heo 40117116969STejun Heo /** 402822d8405STejun Heo * for_each_pool_worker - iterate through all workers of a worker_pool 403822d8405STejun Heo * @worker: iteration cursor 404822d8405STejun Heo * @pool: worker_pool to iterate workers of 405822d8405STejun Heo * 4061258fae7STejun Heo * This must be called with wq_pool_attach_mutex. 407822d8405STejun Heo * 408822d8405STejun Heo * The if/else clause exists only for the lockdep assertion and can be 409822d8405STejun Heo * ignored. 410822d8405STejun Heo */ 411da028469SLai Jiangshan #define for_each_pool_worker(worker, pool) \ 412da028469SLai Jiangshan list_for_each_entry((worker), &(pool)->workers, node) \ 4131258fae7STejun Heo if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \ 414822d8405STejun Heo else 415822d8405STejun Heo 416822d8405STejun Heo /** 41749e3cf44STejun Heo * for_each_pwq - iterate through all pool_workqueues of the specified workqueue 41849e3cf44STejun Heo * @pwq: iteration cursor 41949e3cf44STejun Heo * @wq: the target workqueue 42076af4d93STejun Heo * 42124acfb71SThomas Gleixner * This must be called either with wq->mutex held or RCU read locked. 422794b18bcSTejun Heo * If the pwq needs to be used beyond the locking in effect, the caller is 423794b18bcSTejun Heo * responsible for guaranteeing that the pwq stays online. 42476af4d93STejun Heo * 42576af4d93STejun Heo * The if/else clause exists only for the lockdep assertion and can be 42676af4d93STejun Heo * ignored. 42749e3cf44STejun Heo */ 42849e3cf44STejun Heo #define for_each_pwq(pwq, wq) \ 42976af4d93STejun Heo list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \ 430b09f4fd3SLai Jiangshan if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ 43176af4d93STejun Heo else 432f3421797STejun Heo 433dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 434dc186ad7SThomas Gleixner 435dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 436dc186ad7SThomas Gleixner 43799777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 43899777288SStanislaw Gruszka { 43999777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 44099777288SStanislaw Gruszka } 44199777288SStanislaw Gruszka 442b9fdac7fSDu, Changbin static bool work_is_static_object(void *addr) 443b9fdac7fSDu, Changbin { 444b9fdac7fSDu, Changbin struct work_struct *work = addr; 445b9fdac7fSDu, Changbin 446b9fdac7fSDu, Changbin return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work)); 447b9fdac7fSDu, Changbin } 448b9fdac7fSDu, Changbin 449dc186ad7SThomas Gleixner /* 450dc186ad7SThomas Gleixner * fixup_init is called when: 451dc186ad7SThomas Gleixner * - an active object is initialized 452dc186ad7SThomas Gleixner */ 45302a982a6SDu, Changbin static bool work_fixup_init(void *addr, enum debug_obj_state state) 454dc186ad7SThomas Gleixner { 455dc186ad7SThomas Gleixner struct work_struct *work = addr; 456dc186ad7SThomas Gleixner 457dc186ad7SThomas Gleixner switch (state) { 458dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 459dc186ad7SThomas Gleixner cancel_work_sync(work); 460dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 46102a982a6SDu, Changbin return true; 462dc186ad7SThomas Gleixner default: 46302a982a6SDu, Changbin return false; 464dc186ad7SThomas Gleixner } 465dc186ad7SThomas Gleixner } 466dc186ad7SThomas Gleixner 467dc186ad7SThomas Gleixner /* 468dc186ad7SThomas Gleixner * fixup_free is called when: 469dc186ad7SThomas Gleixner * - an active object is freed 470dc186ad7SThomas Gleixner */ 47102a982a6SDu, Changbin static bool work_fixup_free(void *addr, enum debug_obj_state state) 472dc186ad7SThomas Gleixner { 473dc186ad7SThomas Gleixner struct work_struct *work = addr; 474dc186ad7SThomas Gleixner 475dc186ad7SThomas Gleixner switch (state) { 476dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 477dc186ad7SThomas Gleixner cancel_work_sync(work); 478dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 47902a982a6SDu, Changbin return true; 480dc186ad7SThomas Gleixner default: 48102a982a6SDu, Changbin return false; 482dc186ad7SThomas Gleixner } 483dc186ad7SThomas Gleixner } 484dc186ad7SThomas Gleixner 485dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 486dc186ad7SThomas Gleixner .name = "work_struct", 48799777288SStanislaw Gruszka .debug_hint = work_debug_hint, 488b9fdac7fSDu, Changbin .is_static_object = work_is_static_object, 489dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 490dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 491dc186ad7SThomas Gleixner }; 492dc186ad7SThomas Gleixner 493dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 494dc186ad7SThomas Gleixner { 495dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 496dc186ad7SThomas Gleixner } 497dc186ad7SThomas Gleixner 498dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 499dc186ad7SThomas Gleixner { 500dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 501dc186ad7SThomas Gleixner } 502dc186ad7SThomas Gleixner 503dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 504dc186ad7SThomas Gleixner { 505dc186ad7SThomas Gleixner if (onstack) 506dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 507dc186ad7SThomas Gleixner else 508dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 509dc186ad7SThomas Gleixner } 510dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 511dc186ad7SThomas Gleixner 512dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 513dc186ad7SThomas Gleixner { 514dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 515dc186ad7SThomas Gleixner } 516dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 517dc186ad7SThomas Gleixner 518ea2e64f2SThomas Gleixner void destroy_delayed_work_on_stack(struct delayed_work *work) 519ea2e64f2SThomas Gleixner { 520ea2e64f2SThomas Gleixner destroy_timer_on_stack(&work->timer); 521ea2e64f2SThomas Gleixner debug_object_free(&work->work, &work_debug_descr); 522ea2e64f2SThomas Gleixner } 523ea2e64f2SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); 524ea2e64f2SThomas Gleixner 525dc186ad7SThomas Gleixner #else 526dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 527dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 528dc186ad7SThomas Gleixner #endif 529dc186ad7SThomas Gleixner 5304e8b22bdSLi Bin /** 5314e8b22bdSLi Bin * worker_pool_assign_id - allocate ID and assing it to @pool 5324e8b22bdSLi Bin * @pool: the pool pointer of interest 5334e8b22bdSLi Bin * 5344e8b22bdSLi Bin * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned 5354e8b22bdSLi Bin * successfully, -errno on failure. 5364e8b22bdSLi Bin */ 5379daf9e67STejun Heo static int worker_pool_assign_id(struct worker_pool *pool) 5389daf9e67STejun Heo { 5399daf9e67STejun Heo int ret; 5409daf9e67STejun Heo 54168e13a67SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 5425bcab335STejun Heo 5434e8b22bdSLi Bin ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, 5444e8b22bdSLi Bin GFP_KERNEL); 545229641a6STejun Heo if (ret >= 0) { 546e68035fbSTejun Heo pool->id = ret; 547229641a6STejun Heo return 0; 548229641a6STejun Heo } 5499daf9e67STejun Heo return ret; 5509daf9e67STejun Heo } 5519daf9e67STejun Heo 55276af4d93STejun Heo /** 553df2d5ae4STejun Heo * unbound_pwq_by_node - return the unbound pool_workqueue for the given node 554df2d5ae4STejun Heo * @wq: the target workqueue 555df2d5ae4STejun Heo * @node: the node ID 556df2d5ae4STejun Heo * 55724acfb71SThomas Gleixner * This must be called with any of wq_pool_mutex, wq->mutex or RCU 5585b95e1afSLai Jiangshan * read locked. 559df2d5ae4STejun Heo * If the pwq needs to be used beyond the locking in effect, the caller is 560df2d5ae4STejun Heo * responsible for guaranteeing that the pwq stays online. 561d185af30SYacine Belkadi * 562d185af30SYacine Belkadi * Return: The unbound pool_workqueue for @node. 563df2d5ae4STejun Heo */ 564df2d5ae4STejun Heo static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, 565df2d5ae4STejun Heo int node) 566df2d5ae4STejun Heo { 5675b95e1afSLai Jiangshan assert_rcu_or_wq_mutex_or_pool_mutex(wq); 568d6e022f1STejun Heo 569d6e022f1STejun Heo /* 570d6e022f1STejun Heo * XXX: @node can be NUMA_NO_NODE if CPU goes offline while a 571d6e022f1STejun Heo * delayed item is pending. The plan is to keep CPU -> NODE 572d6e022f1STejun Heo * mapping valid and stable across CPU on/offlines. Once that 573d6e022f1STejun Heo * happens, this workaround can be removed. 574d6e022f1STejun Heo */ 575d6e022f1STejun Heo if (unlikely(node == NUMA_NO_NODE)) 576d6e022f1STejun Heo return wq->dfl_pwq; 577d6e022f1STejun Heo 578df2d5ae4STejun Heo return rcu_dereference_raw(wq->numa_pwq_tbl[node]); 579df2d5ae4STejun Heo } 580df2d5ae4STejun Heo 58173f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 58273f53c4aSTejun Heo { 58373f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 58473f53c4aSTejun Heo } 58573f53c4aSTejun Heo 58673f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 58773f53c4aSTejun Heo { 58873f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 58973f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 59073f53c4aSTejun Heo } 59173f53c4aSTejun Heo 59273f53c4aSTejun Heo static int work_next_color(int color) 59373f53c4aSTejun Heo { 59473f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 595a848e3b6SOleg Nesterov } 596a848e3b6SOleg Nesterov 5974594bf15SDavid Howells /* 598112202d9STejun Heo * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data 599112202d9STejun Heo * contain the pointer to the queued pwq. Once execution starts, the flag 6007c3eed5cSTejun Heo * is cleared and the high bits contain OFFQ flags and pool ID. 6017a22ad75STejun Heo * 602112202d9STejun Heo * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() 603112202d9STejun Heo * and clear_work_data() can be used to set the pwq, pool or clear 604bbb68dfaSTejun Heo * work->data. These functions should only be called while the work is 605bbb68dfaSTejun Heo * owned - ie. while the PENDING bit is set. 6067a22ad75STejun Heo * 607112202d9STejun Heo * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq 6087c3eed5cSTejun Heo * corresponding to a work. Pool is available once the work has been 609112202d9STejun Heo * queued anywhere after initialization until it is sync canceled. pwq is 6107c3eed5cSTejun Heo * available only while the work item is queued. 611bbb68dfaSTejun Heo * 612bbb68dfaSTejun Heo * %WORK_OFFQ_CANCELING is used to mark a work item which is being 613bbb68dfaSTejun Heo * canceled. While being canceled, a work item may have its PENDING set 614bbb68dfaSTejun Heo * but stay off timer and worklist for arbitrarily long and nobody should 615bbb68dfaSTejun Heo * try to steal the PENDING bit. 6164594bf15SDavid Howells */ 6177a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 6187a22ad75STejun Heo unsigned long flags) 6197a22ad75STejun Heo { 6206183c009STejun Heo WARN_ON_ONCE(!work_pending(work)); 6217a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 6227a22ad75STejun Heo } 6237a22ad75STejun Heo 624112202d9STejun Heo static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, 6254690c4abSTejun Heo unsigned long extra_flags) 626365970a1SDavid Howells { 627112202d9STejun Heo set_work_data(work, (unsigned long)pwq, 628112202d9STejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); 629365970a1SDavid Howells } 630365970a1SDavid Howells 6314468a00fSLai Jiangshan static void set_work_pool_and_keep_pending(struct work_struct *work, 6324468a00fSLai Jiangshan int pool_id) 6334468a00fSLai Jiangshan { 6344468a00fSLai Jiangshan set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 6354468a00fSLai Jiangshan WORK_STRUCT_PENDING); 6364468a00fSLai Jiangshan } 6374468a00fSLai Jiangshan 6387c3eed5cSTejun Heo static void set_work_pool_and_clear_pending(struct work_struct *work, 6397c3eed5cSTejun Heo int pool_id) 6404d707b9fSOleg Nesterov { 64123657bb1STejun Heo /* 64223657bb1STejun Heo * The following wmb is paired with the implied mb in 64323657bb1STejun Heo * test_and_set_bit(PENDING) and ensures all updates to @work made 64423657bb1STejun Heo * here are visible to and precede any updates by the next PENDING 64523657bb1STejun Heo * owner. 64623657bb1STejun Heo */ 64723657bb1STejun Heo smp_wmb(); 6487c3eed5cSTejun Heo set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); 649346c09f8SRoman Pen /* 650346c09f8SRoman Pen * The following mb guarantees that previous clear of a PENDING bit 651346c09f8SRoman Pen * will not be reordered with any speculative LOADS or STORES from 652346c09f8SRoman Pen * work->current_func, which is executed afterwards. This possible 6538bdc6201SLiu Song * reordering can lead to a missed execution on attempt to queue 654346c09f8SRoman Pen * the same @work. E.g. consider this case: 655346c09f8SRoman Pen * 656346c09f8SRoman Pen * CPU#0 CPU#1 657346c09f8SRoman Pen * ---------------------------- -------------------------------- 658346c09f8SRoman Pen * 659346c09f8SRoman Pen * 1 STORE event_indicated 660346c09f8SRoman Pen * 2 queue_work_on() { 661346c09f8SRoman Pen * 3 test_and_set_bit(PENDING) 662346c09f8SRoman Pen * 4 } set_..._and_clear_pending() { 663346c09f8SRoman Pen * 5 set_work_data() # clear bit 664346c09f8SRoman Pen * 6 smp_mb() 665346c09f8SRoman Pen * 7 work->current_func() { 666346c09f8SRoman Pen * 8 LOAD event_indicated 667346c09f8SRoman Pen * } 668346c09f8SRoman Pen * 669346c09f8SRoman Pen * Without an explicit full barrier speculative LOAD on line 8 can 670346c09f8SRoman Pen * be executed before CPU#0 does STORE on line 1. If that happens, 671346c09f8SRoman Pen * CPU#0 observes the PENDING bit is still set and new execution of 672346c09f8SRoman Pen * a @work is not queued in a hope, that CPU#1 will eventually 673346c09f8SRoman Pen * finish the queued @work. Meanwhile CPU#1 does not see 674346c09f8SRoman Pen * event_indicated is set, because speculative LOAD was executed 675346c09f8SRoman Pen * before actual STORE. 676346c09f8SRoman Pen */ 677346c09f8SRoman Pen smp_mb(); 6784d707b9fSOleg Nesterov } 6794d707b9fSOleg Nesterov 6807a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 681365970a1SDavid Howells { 6827c3eed5cSTejun Heo smp_wmb(); /* see set_work_pool_and_clear_pending() */ 6837c3eed5cSTejun Heo set_work_data(work, WORK_STRUCT_NO_POOL, 0); 6847a22ad75STejun Heo } 6857a22ad75STejun Heo 686112202d9STejun Heo static struct pool_workqueue *get_work_pwq(struct work_struct *work) 6877a22ad75STejun Heo { 688e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 6897a22ad75STejun Heo 690112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 691e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 692e120153dSTejun Heo else 693e120153dSTejun Heo return NULL; 6947a22ad75STejun Heo } 6957a22ad75STejun Heo 6967c3eed5cSTejun Heo /** 6977c3eed5cSTejun Heo * get_work_pool - return the worker_pool a given work was associated with 6987c3eed5cSTejun Heo * @work: the work item of interest 6997c3eed5cSTejun Heo * 70068e13a67SLai Jiangshan * Pools are created and destroyed under wq_pool_mutex, and allows read 70124acfb71SThomas Gleixner * access under RCU read lock. As such, this function should be 70224acfb71SThomas Gleixner * called under wq_pool_mutex or inside of a rcu_read_lock() region. 703fa1b54e6STejun Heo * 704fa1b54e6STejun Heo * All fields of the returned pool are accessible as long as the above 705fa1b54e6STejun Heo * mentioned locking is in effect. If the returned pool needs to be used 706fa1b54e6STejun Heo * beyond the critical section, the caller is responsible for ensuring the 707fa1b54e6STejun Heo * returned pool is and stays online. 708d185af30SYacine Belkadi * 709d185af30SYacine Belkadi * Return: The worker_pool @work was last associated with. %NULL if none. 7107c3eed5cSTejun Heo */ 7117c3eed5cSTejun Heo static struct worker_pool *get_work_pool(struct work_struct *work) 7127a22ad75STejun Heo { 713e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 7147c3eed5cSTejun Heo int pool_id; 7157a22ad75STejun Heo 71668e13a67SLai Jiangshan assert_rcu_or_pool_mutex(); 717fa1b54e6STejun Heo 718112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 719112202d9STejun Heo return ((struct pool_workqueue *) 7207c3eed5cSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->pool; 7217a22ad75STejun Heo 7227c3eed5cSTejun Heo pool_id = data >> WORK_OFFQ_POOL_SHIFT; 7237c3eed5cSTejun Heo if (pool_id == WORK_OFFQ_POOL_NONE) 7247a22ad75STejun Heo return NULL; 7257a22ad75STejun Heo 726fa1b54e6STejun Heo return idr_find(&worker_pool_idr, pool_id); 7277c3eed5cSTejun Heo } 7287c3eed5cSTejun Heo 7297c3eed5cSTejun Heo /** 7307c3eed5cSTejun Heo * get_work_pool_id - return the worker pool ID a given work is associated with 7317c3eed5cSTejun Heo * @work: the work item of interest 7327c3eed5cSTejun Heo * 733d185af30SYacine Belkadi * Return: The worker_pool ID @work was last associated with. 7347c3eed5cSTejun Heo * %WORK_OFFQ_POOL_NONE if none. 7357c3eed5cSTejun Heo */ 7367c3eed5cSTejun Heo static int get_work_pool_id(struct work_struct *work) 7377c3eed5cSTejun Heo { 73854d5b7d0SLai Jiangshan unsigned long data = atomic_long_read(&work->data); 7397c3eed5cSTejun Heo 740112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 741112202d9STejun Heo return ((struct pool_workqueue *) 74254d5b7d0SLai Jiangshan (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; 74354d5b7d0SLai Jiangshan 74454d5b7d0SLai Jiangshan return data >> WORK_OFFQ_POOL_SHIFT; 7457c3eed5cSTejun Heo } 7467c3eed5cSTejun Heo 747bbb68dfaSTejun Heo static void mark_work_canceling(struct work_struct *work) 748bbb68dfaSTejun Heo { 7497c3eed5cSTejun Heo unsigned long pool_id = get_work_pool_id(work); 750bbb68dfaSTejun Heo 7517c3eed5cSTejun Heo pool_id <<= WORK_OFFQ_POOL_SHIFT; 7527c3eed5cSTejun Heo set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); 753bbb68dfaSTejun Heo } 754bbb68dfaSTejun Heo 755bbb68dfaSTejun Heo static bool work_is_canceling(struct work_struct *work) 756bbb68dfaSTejun Heo { 757bbb68dfaSTejun Heo unsigned long data = atomic_long_read(&work->data); 758bbb68dfaSTejun Heo 759112202d9STejun Heo return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); 760bbb68dfaSTejun Heo } 761bbb68dfaSTejun Heo 762e22bee78STejun Heo /* 7633270476aSTejun Heo * Policy functions. These define the policies on how the global worker 7643270476aSTejun Heo * pools are managed. Unless noted otherwise, these functions assume that 765d565ed63STejun Heo * they're being called with pool->lock held. 766e22bee78STejun Heo */ 767e22bee78STejun Heo 76863d95a91STejun Heo static bool __need_more_worker(struct worker_pool *pool) 769649027d7STejun Heo { 770e19e397aSTejun Heo return !atomic_read(&pool->nr_running); 771649027d7STejun Heo } 772649027d7STejun Heo 773e22bee78STejun Heo /* 774e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 775e22bee78STejun Heo * running workers. 776974271c4STejun Heo * 777974271c4STejun Heo * Note that, because unbound workers never contribute to nr_running, this 778706026c2STejun Heo * function will always return %true for unbound pools as long as the 779974271c4STejun Heo * worklist isn't empty. 780e22bee78STejun Heo */ 78163d95a91STejun Heo static bool need_more_worker(struct worker_pool *pool) 782e22bee78STejun Heo { 78363d95a91STejun Heo return !list_empty(&pool->worklist) && __need_more_worker(pool); 784e22bee78STejun Heo } 785e22bee78STejun Heo 786e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 78763d95a91STejun Heo static bool may_start_working(struct worker_pool *pool) 788e22bee78STejun Heo { 78963d95a91STejun Heo return pool->nr_idle; 790e22bee78STejun Heo } 791e22bee78STejun Heo 792e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 79363d95a91STejun Heo static bool keep_working(struct worker_pool *pool) 794e22bee78STejun Heo { 795e19e397aSTejun Heo return !list_empty(&pool->worklist) && 796e19e397aSTejun Heo atomic_read(&pool->nr_running) <= 1; 797e22bee78STejun Heo } 798e22bee78STejun Heo 799e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 80063d95a91STejun Heo static bool need_to_create_worker(struct worker_pool *pool) 801e22bee78STejun Heo { 80263d95a91STejun Heo return need_more_worker(pool) && !may_start_working(pool); 803e22bee78STejun Heo } 804e22bee78STejun Heo 805e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 80663d95a91STejun Heo static bool too_many_workers(struct worker_pool *pool) 807e22bee78STejun Heo { 808692b4825STejun Heo bool managing = pool->flags & POOL_MANAGER_ACTIVE; 80963d95a91STejun Heo int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 81063d95a91STejun Heo int nr_busy = pool->nr_workers - nr_idle; 811e22bee78STejun Heo 812e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 813e22bee78STejun Heo } 814e22bee78STejun Heo 815e22bee78STejun Heo /* 816e22bee78STejun Heo * Wake up functions. 817e22bee78STejun Heo */ 818e22bee78STejun Heo 8191037de36SLai Jiangshan /* Return the first idle worker. Safe with preemption disabled */ 8201037de36SLai Jiangshan static struct worker *first_idle_worker(struct worker_pool *pool) 8217e11629dSTejun Heo { 82263d95a91STejun Heo if (unlikely(list_empty(&pool->idle_list))) 8237e11629dSTejun Heo return NULL; 8247e11629dSTejun Heo 82563d95a91STejun Heo return list_first_entry(&pool->idle_list, struct worker, entry); 8267e11629dSTejun Heo } 8277e11629dSTejun Heo 8287e11629dSTejun Heo /** 8297e11629dSTejun Heo * wake_up_worker - wake up an idle worker 83063d95a91STejun Heo * @pool: worker pool to wake worker from 8317e11629dSTejun Heo * 83263d95a91STejun Heo * Wake up the first idle worker of @pool. 8337e11629dSTejun Heo * 8347e11629dSTejun Heo * CONTEXT: 835d565ed63STejun Heo * spin_lock_irq(pool->lock). 8367e11629dSTejun Heo */ 83763d95a91STejun Heo static void wake_up_worker(struct worker_pool *pool) 8387e11629dSTejun Heo { 8391037de36SLai Jiangshan struct worker *worker = first_idle_worker(pool); 8407e11629dSTejun Heo 8417e11629dSTejun Heo if (likely(worker)) 8427e11629dSTejun Heo wake_up_process(worker->task); 8437e11629dSTejun Heo } 8447e11629dSTejun Heo 8454690c4abSTejun Heo /** 8466d25be57SThomas Gleixner * wq_worker_running - a worker is running again 847e22bee78STejun Heo * @task: task waking up 848e22bee78STejun Heo * 8496d25be57SThomas Gleixner * This function is called when a worker returns from schedule() 850e22bee78STejun Heo */ 8516d25be57SThomas Gleixner void wq_worker_running(struct task_struct *task) 852e22bee78STejun Heo { 853e22bee78STejun Heo struct worker *worker = kthread_data(task); 854e22bee78STejun Heo 8556d25be57SThomas Gleixner if (!worker->sleeping) 8566d25be57SThomas Gleixner return; 8576d25be57SThomas Gleixner if (!(worker->flags & WORKER_NOT_RUNNING)) 858e19e397aSTejun Heo atomic_inc(&worker->pool->nr_running); 8596d25be57SThomas Gleixner worker->sleeping = 0; 86036576000SJoonsoo Kim } 861e22bee78STejun Heo 862e22bee78STejun Heo /** 863e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 864e22bee78STejun Heo * @task: task going to sleep 865e22bee78STejun Heo * 8666d25be57SThomas Gleixner * This function is called from schedule() when a busy worker is 8676d25be57SThomas Gleixner * going to sleep. 868e22bee78STejun Heo */ 8696d25be57SThomas Gleixner void wq_worker_sleeping(struct task_struct *task) 870e22bee78STejun Heo { 8716d25be57SThomas Gleixner struct worker *next, *worker = kthread_data(task); 872111c225aSTejun Heo struct worker_pool *pool; 873e22bee78STejun Heo 874111c225aSTejun Heo /* 875111c225aSTejun Heo * Rescuers, which may not have all the fields set up like normal 876111c225aSTejun Heo * workers, also reach here, let's not access anything before 877111c225aSTejun Heo * checking NOT_RUNNING. 878111c225aSTejun Heo */ 8792d64672eSSteven Rostedt if (worker->flags & WORKER_NOT_RUNNING) 8806d25be57SThomas Gleixner return; 881e22bee78STejun Heo 882111c225aSTejun Heo pool = worker->pool; 883111c225aSTejun Heo 8846d25be57SThomas Gleixner if (WARN_ON_ONCE(worker->sleeping)) 8856d25be57SThomas Gleixner return; 8866d25be57SThomas Gleixner 8876d25be57SThomas Gleixner worker->sleeping = 1; 8886d25be57SThomas Gleixner spin_lock_irq(&pool->lock); 889e22bee78STejun Heo 890e22bee78STejun Heo /* 891e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 892e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 893e22bee78STejun Heo * Please read comment there. 894e22bee78STejun Heo * 895628c78e7STejun Heo * NOT_RUNNING is clear. This means that we're bound to and 896628c78e7STejun Heo * running on the local cpu w/ rq lock held and preemption 897628c78e7STejun Heo * disabled, which in turn means that none else could be 898d565ed63STejun Heo * manipulating idle_list, so dereferencing idle_list without pool 899628c78e7STejun Heo * lock is safe. 900e22bee78STejun Heo */ 901e19e397aSTejun Heo if (atomic_dec_and_test(&pool->nr_running) && 9026d25be57SThomas Gleixner !list_empty(&pool->worklist)) { 9036d25be57SThomas Gleixner next = first_idle_worker(pool); 9046d25be57SThomas Gleixner if (next) 9056d25be57SThomas Gleixner wake_up_process(next->task); 9066d25be57SThomas Gleixner } 9076d25be57SThomas Gleixner spin_unlock_irq(&pool->lock); 908e22bee78STejun Heo } 909e22bee78STejun Heo 910e22bee78STejun Heo /** 9111b69ac6bSJohannes Weiner * wq_worker_last_func - retrieve worker's last work function 9128194fe94SBart Van Assche * @task: Task to retrieve last work function of. 9131b69ac6bSJohannes Weiner * 9141b69ac6bSJohannes Weiner * Determine the last function a worker executed. This is called from 9151b69ac6bSJohannes Weiner * the scheduler to get a worker's last known identity. 9161b69ac6bSJohannes Weiner * 9171b69ac6bSJohannes Weiner * CONTEXT: 9181b69ac6bSJohannes Weiner * spin_lock_irq(rq->lock) 9191b69ac6bSJohannes Weiner * 9204b047002SJohannes Weiner * This function is called during schedule() when a kworker is going 9214b047002SJohannes Weiner * to sleep. It's used by psi to identify aggregation workers during 9224b047002SJohannes Weiner * dequeuing, to allow periodic aggregation to shut-off when that 9234b047002SJohannes Weiner * worker is the last task in the system or cgroup to go to sleep. 9244b047002SJohannes Weiner * 9254b047002SJohannes Weiner * As this function doesn't involve any workqueue-related locking, it 9264b047002SJohannes Weiner * only returns stable values when called from inside the scheduler's 9274b047002SJohannes Weiner * queuing and dequeuing paths, when @task, which must be a kworker, 9284b047002SJohannes Weiner * is guaranteed to not be processing any works. 9294b047002SJohannes Weiner * 9301b69ac6bSJohannes Weiner * Return: 9311b69ac6bSJohannes Weiner * The last work function %current executed as a worker, NULL if it 9321b69ac6bSJohannes Weiner * hasn't executed any work yet. 9331b69ac6bSJohannes Weiner */ 9341b69ac6bSJohannes Weiner work_func_t wq_worker_last_func(struct task_struct *task) 9351b69ac6bSJohannes Weiner { 9361b69ac6bSJohannes Weiner struct worker *worker = kthread_data(task); 9371b69ac6bSJohannes Weiner 9381b69ac6bSJohannes Weiner return worker->last_func; 9391b69ac6bSJohannes Weiner } 9401b69ac6bSJohannes Weiner 9411b69ac6bSJohannes Weiner /** 942e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 943cb444766STejun Heo * @worker: self 944d302f017STejun Heo * @flags: flags to set 945d302f017STejun Heo * 946228f1d00SLai Jiangshan * Set @flags in @worker->flags and adjust nr_running accordingly. 947d302f017STejun Heo * 948cb444766STejun Heo * CONTEXT: 949d565ed63STejun Heo * spin_lock_irq(pool->lock) 950d302f017STejun Heo */ 951228f1d00SLai Jiangshan static inline void worker_set_flags(struct worker *worker, unsigned int flags) 952d302f017STejun Heo { 953bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 954e22bee78STejun Heo 955cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 956cb444766STejun Heo 957228f1d00SLai Jiangshan /* If transitioning into NOT_RUNNING, adjust nr_running. */ 958e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 959e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 960e19e397aSTejun Heo atomic_dec(&pool->nr_running); 961e22bee78STejun Heo } 962e22bee78STejun Heo 963d302f017STejun Heo worker->flags |= flags; 964d302f017STejun Heo } 965d302f017STejun Heo 966d302f017STejun Heo /** 967e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 968cb444766STejun Heo * @worker: self 969d302f017STejun Heo * @flags: flags to clear 970d302f017STejun Heo * 971e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 972d302f017STejun Heo * 973cb444766STejun Heo * CONTEXT: 974d565ed63STejun Heo * spin_lock_irq(pool->lock) 975d302f017STejun Heo */ 976d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 977d302f017STejun Heo { 97863d95a91STejun Heo struct worker_pool *pool = worker->pool; 979e22bee78STejun Heo unsigned int oflags = worker->flags; 980e22bee78STejun Heo 981cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 982cb444766STejun Heo 983d302f017STejun Heo worker->flags &= ~flags; 984e22bee78STejun Heo 98542c025f3STejun Heo /* 98642c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 98742c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 98842c025f3STejun Heo * of multiple flags, not a single flag. 98942c025f3STejun Heo */ 990e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 991e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 992e19e397aSTejun Heo atomic_inc(&pool->nr_running); 993d302f017STejun Heo } 994d302f017STejun Heo 995d302f017STejun Heo /** 9968cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 997c9e7cf27STejun Heo * @pool: pool of interest 9988cca0eeaSTejun Heo * @work: work to find worker for 9998cca0eeaSTejun Heo * 1000c9e7cf27STejun Heo * Find a worker which is executing @work on @pool by searching 1001c9e7cf27STejun Heo * @pool->busy_hash which is keyed by the address of @work. For a worker 1002a2c1c57bSTejun Heo * to match, its current execution should match the address of @work and 1003a2c1c57bSTejun Heo * its work function. This is to avoid unwanted dependency between 1004a2c1c57bSTejun Heo * unrelated work executions through a work item being recycled while still 1005a2c1c57bSTejun Heo * being executed. 1006a2c1c57bSTejun Heo * 1007a2c1c57bSTejun Heo * This is a bit tricky. A work item may be freed once its execution 1008a2c1c57bSTejun Heo * starts and nothing prevents the freed area from being recycled for 1009a2c1c57bSTejun Heo * another work item. If the same work item address ends up being reused 1010a2c1c57bSTejun Heo * before the original execution finishes, workqueue will identify the 1011a2c1c57bSTejun Heo * recycled work item as currently executing and make it wait until the 1012a2c1c57bSTejun Heo * current execution finishes, introducing an unwanted dependency. 1013a2c1c57bSTejun Heo * 1014c5aa87bbSTejun Heo * This function checks the work item address and work function to avoid 1015c5aa87bbSTejun Heo * false positives. Note that this isn't complete as one may construct a 1016c5aa87bbSTejun Heo * work function which can introduce dependency onto itself through a 1017c5aa87bbSTejun Heo * recycled work item. Well, if somebody wants to shoot oneself in the 1018c5aa87bbSTejun Heo * foot that badly, there's only so much we can do, and if such deadlock 1019c5aa87bbSTejun Heo * actually occurs, it should be easy to locate the culprit work function. 10208cca0eeaSTejun Heo * 10218cca0eeaSTejun Heo * CONTEXT: 1022d565ed63STejun Heo * spin_lock_irq(pool->lock). 10238cca0eeaSTejun Heo * 1024d185af30SYacine Belkadi * Return: 1025d185af30SYacine Belkadi * Pointer to worker which is executing @work if found, %NULL 10268cca0eeaSTejun Heo * otherwise. 10278cca0eeaSTejun Heo */ 1028c9e7cf27STejun Heo static struct worker *find_worker_executing_work(struct worker_pool *pool, 10298cca0eeaSTejun Heo struct work_struct *work) 10308cca0eeaSTejun Heo { 103142f8570fSSasha Levin struct worker *worker; 103242f8570fSSasha Levin 1033b67bfe0dSSasha Levin hash_for_each_possible(pool->busy_hash, worker, hentry, 1034a2c1c57bSTejun Heo (unsigned long)work) 1035a2c1c57bSTejun Heo if (worker->current_work == work && 1036a2c1c57bSTejun Heo worker->current_func == work->func) 103742f8570fSSasha Levin return worker; 103842f8570fSSasha Levin 103942f8570fSSasha Levin return NULL; 10408cca0eeaSTejun Heo } 10418cca0eeaSTejun Heo 10428cca0eeaSTejun Heo /** 1043bf4ede01STejun Heo * move_linked_works - move linked works to a list 1044bf4ede01STejun Heo * @work: start of series of works to be scheduled 1045bf4ede01STejun Heo * @head: target list to append @work to 1046402dd89dSShailendra Verma * @nextp: out parameter for nested worklist walking 1047bf4ede01STejun Heo * 1048bf4ede01STejun Heo * Schedule linked works starting from @work to @head. Work series to 1049bf4ede01STejun Heo * be scheduled starts at @work and includes any consecutive work with 1050bf4ede01STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 1051bf4ede01STejun Heo * 1052bf4ede01STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 1053bf4ede01STejun Heo * the last scheduled work. This allows move_linked_works() to be 1054bf4ede01STejun Heo * nested inside outer list_for_each_entry_safe(). 1055bf4ede01STejun Heo * 1056bf4ede01STejun Heo * CONTEXT: 1057d565ed63STejun Heo * spin_lock_irq(pool->lock). 1058bf4ede01STejun Heo */ 1059bf4ede01STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1060bf4ede01STejun Heo struct work_struct **nextp) 1061bf4ede01STejun Heo { 1062bf4ede01STejun Heo struct work_struct *n; 1063bf4ede01STejun Heo 1064bf4ede01STejun Heo /* 1065bf4ede01STejun Heo * Linked worklist will always end before the end of the list, 1066bf4ede01STejun Heo * use NULL for list head. 1067bf4ede01STejun Heo */ 1068bf4ede01STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1069bf4ede01STejun Heo list_move_tail(&work->entry, head); 1070bf4ede01STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1071bf4ede01STejun Heo break; 1072bf4ede01STejun Heo } 1073bf4ede01STejun Heo 1074bf4ede01STejun Heo /* 1075bf4ede01STejun Heo * If we're already inside safe list traversal and have moved 1076bf4ede01STejun Heo * multiple works to the scheduled queue, the next position 1077bf4ede01STejun Heo * needs to be updated. 1078bf4ede01STejun Heo */ 1079bf4ede01STejun Heo if (nextp) 1080bf4ede01STejun Heo *nextp = n; 1081bf4ede01STejun Heo } 1082bf4ede01STejun Heo 10838864b4e5STejun Heo /** 10848864b4e5STejun Heo * get_pwq - get an extra reference on the specified pool_workqueue 10858864b4e5STejun Heo * @pwq: pool_workqueue to get 10868864b4e5STejun Heo * 10878864b4e5STejun Heo * Obtain an extra reference on @pwq. The caller should guarantee that 10888864b4e5STejun Heo * @pwq has positive refcnt and be holding the matching pool->lock. 10898864b4e5STejun Heo */ 10908864b4e5STejun Heo static void get_pwq(struct pool_workqueue *pwq) 10918864b4e5STejun Heo { 10928864b4e5STejun Heo lockdep_assert_held(&pwq->pool->lock); 10938864b4e5STejun Heo WARN_ON_ONCE(pwq->refcnt <= 0); 10948864b4e5STejun Heo pwq->refcnt++; 10958864b4e5STejun Heo } 10968864b4e5STejun Heo 10978864b4e5STejun Heo /** 10988864b4e5STejun Heo * put_pwq - put a pool_workqueue reference 10998864b4e5STejun Heo * @pwq: pool_workqueue to put 11008864b4e5STejun Heo * 11018864b4e5STejun Heo * Drop a reference of @pwq. If its refcnt reaches zero, schedule its 11028864b4e5STejun Heo * destruction. The caller should be holding the matching pool->lock. 11038864b4e5STejun Heo */ 11048864b4e5STejun Heo static void put_pwq(struct pool_workqueue *pwq) 11058864b4e5STejun Heo { 11068864b4e5STejun Heo lockdep_assert_held(&pwq->pool->lock); 11078864b4e5STejun Heo if (likely(--pwq->refcnt)) 11088864b4e5STejun Heo return; 11098864b4e5STejun Heo if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) 11108864b4e5STejun Heo return; 11118864b4e5STejun Heo /* 11128864b4e5STejun Heo * @pwq can't be released under pool->lock, bounce to 11138864b4e5STejun Heo * pwq_unbound_release_workfn(). This never recurses on the same 11148864b4e5STejun Heo * pool->lock as this path is taken only for unbound workqueues and 11158864b4e5STejun Heo * the release work item is scheduled on a per-cpu workqueue. To 11168864b4e5STejun Heo * avoid lockdep warning, unbound pool->locks are given lockdep 11178864b4e5STejun Heo * subclass of 1 in get_unbound_pool(). 11188864b4e5STejun Heo */ 11198864b4e5STejun Heo schedule_work(&pwq->unbound_release_work); 11208864b4e5STejun Heo } 11218864b4e5STejun Heo 1122dce90d47STejun Heo /** 1123dce90d47STejun Heo * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock 1124dce90d47STejun Heo * @pwq: pool_workqueue to put (can be %NULL) 1125dce90d47STejun Heo * 1126dce90d47STejun Heo * put_pwq() with locking. This function also allows %NULL @pwq. 1127dce90d47STejun Heo */ 1128dce90d47STejun Heo static void put_pwq_unlocked(struct pool_workqueue *pwq) 1129dce90d47STejun Heo { 1130dce90d47STejun Heo if (pwq) { 1131dce90d47STejun Heo /* 113224acfb71SThomas Gleixner * As both pwqs and pools are RCU protected, the 1133dce90d47STejun Heo * following lock operations are safe. 1134dce90d47STejun Heo */ 1135dce90d47STejun Heo spin_lock_irq(&pwq->pool->lock); 1136dce90d47STejun Heo put_pwq(pwq); 1137dce90d47STejun Heo spin_unlock_irq(&pwq->pool->lock); 1138dce90d47STejun Heo } 1139dce90d47STejun Heo } 1140dce90d47STejun Heo 1141112202d9STejun Heo static void pwq_activate_delayed_work(struct work_struct *work) 1142bf4ede01STejun Heo { 1143112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 1144bf4ede01STejun Heo 1145bf4ede01STejun Heo trace_workqueue_activate_work(work); 114682607adcSTejun Heo if (list_empty(&pwq->pool->worklist)) 114782607adcSTejun Heo pwq->pool->watchdog_ts = jiffies; 1148112202d9STejun Heo move_linked_works(work, &pwq->pool->worklist, NULL); 1149bf4ede01STejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 1150112202d9STejun Heo pwq->nr_active++; 1151bf4ede01STejun Heo } 1152bf4ede01STejun Heo 1153112202d9STejun Heo static void pwq_activate_first_delayed(struct pool_workqueue *pwq) 11543aa62497SLai Jiangshan { 1155112202d9STejun Heo struct work_struct *work = list_first_entry(&pwq->delayed_works, 11563aa62497SLai Jiangshan struct work_struct, entry); 11573aa62497SLai Jiangshan 1158112202d9STejun Heo pwq_activate_delayed_work(work); 11593aa62497SLai Jiangshan } 11603aa62497SLai Jiangshan 1161bf4ede01STejun Heo /** 1162112202d9STejun Heo * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight 1163112202d9STejun Heo * @pwq: pwq of interest 1164bf4ede01STejun Heo * @color: color of work which left the queue 1165bf4ede01STejun Heo * 1166bf4ede01STejun Heo * A work either has completed or is removed from pending queue, 1167112202d9STejun Heo * decrement nr_in_flight of its pwq and handle workqueue flushing. 1168bf4ede01STejun Heo * 1169bf4ede01STejun Heo * CONTEXT: 1170d565ed63STejun Heo * spin_lock_irq(pool->lock). 1171bf4ede01STejun Heo */ 1172112202d9STejun Heo static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) 1173bf4ede01STejun Heo { 11748864b4e5STejun Heo /* uncolored work items don't participate in flushing or nr_active */ 1175bf4ede01STejun Heo if (color == WORK_NO_COLOR) 11768864b4e5STejun Heo goto out_put; 1177bf4ede01STejun Heo 1178112202d9STejun Heo pwq->nr_in_flight[color]--; 1179bf4ede01STejun Heo 1180112202d9STejun Heo pwq->nr_active--; 1181112202d9STejun Heo if (!list_empty(&pwq->delayed_works)) { 1182bf4ede01STejun Heo /* one down, submit a delayed one */ 1183112202d9STejun Heo if (pwq->nr_active < pwq->max_active) 1184112202d9STejun Heo pwq_activate_first_delayed(pwq); 1185bf4ede01STejun Heo } 1186bf4ede01STejun Heo 1187bf4ede01STejun Heo /* is flush in progress and are we at the flushing tip? */ 1188112202d9STejun Heo if (likely(pwq->flush_color != color)) 11898864b4e5STejun Heo goto out_put; 1190bf4ede01STejun Heo 1191bf4ede01STejun Heo /* are there still in-flight works? */ 1192112202d9STejun Heo if (pwq->nr_in_flight[color]) 11938864b4e5STejun Heo goto out_put; 1194bf4ede01STejun Heo 1195112202d9STejun Heo /* this pwq is done, clear flush_color */ 1196112202d9STejun Heo pwq->flush_color = -1; 1197bf4ede01STejun Heo 1198bf4ede01STejun Heo /* 1199112202d9STejun Heo * If this was the last pwq, wake up the first flusher. It 1200bf4ede01STejun Heo * will handle the rest. 1201bf4ede01STejun Heo */ 1202112202d9STejun Heo if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) 1203112202d9STejun Heo complete(&pwq->wq->first_flusher->done); 12048864b4e5STejun Heo out_put: 12058864b4e5STejun Heo put_pwq(pwq); 1206bf4ede01STejun Heo } 1207bf4ede01STejun Heo 120836e227d2STejun Heo /** 1209bbb68dfaSTejun Heo * try_to_grab_pending - steal work item from worklist and disable irq 121036e227d2STejun Heo * @work: work item to steal 121136e227d2STejun Heo * @is_dwork: @work is a delayed_work 1212bbb68dfaSTejun Heo * @flags: place to store irq state 121336e227d2STejun Heo * 121436e227d2STejun Heo * Try to grab PENDING bit of @work. This function can handle @work in any 1215d185af30SYacine Belkadi * stable state - idle, on timer or on worklist. 121636e227d2STejun Heo * 1217d185af30SYacine Belkadi * Return: 121836e227d2STejun Heo * 1 if @work was pending and we successfully stole PENDING 121936e227d2STejun Heo * 0 if @work was idle and we claimed PENDING 122036e227d2STejun Heo * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 1221bbb68dfaSTejun Heo * -ENOENT if someone else is canceling @work, this state may persist 1222bbb68dfaSTejun Heo * for arbitrarily long 122336e227d2STejun Heo * 1224d185af30SYacine Belkadi * Note: 1225bbb68dfaSTejun Heo * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 1226e0aecdd8STejun Heo * interrupted while holding PENDING and @work off queue, irq must be 1227e0aecdd8STejun Heo * disabled on entry. This, combined with delayed_work->timer being 1228e0aecdd8STejun Heo * irqsafe, ensures that we return -EAGAIN for finite short period of time. 1229bbb68dfaSTejun Heo * 1230bbb68dfaSTejun Heo * On successful return, >= 0, irq is disabled and the caller is 1231bbb68dfaSTejun Heo * responsible for releasing it using local_irq_restore(*@flags). 1232bbb68dfaSTejun Heo * 1233e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 1234bf4ede01STejun Heo */ 1235bbb68dfaSTejun Heo static int try_to_grab_pending(struct work_struct *work, bool is_dwork, 1236bbb68dfaSTejun Heo unsigned long *flags) 1237bf4ede01STejun Heo { 1238d565ed63STejun Heo struct worker_pool *pool; 1239112202d9STejun Heo struct pool_workqueue *pwq; 1240bf4ede01STejun Heo 1241bbb68dfaSTejun Heo local_irq_save(*flags); 1242bbb68dfaSTejun Heo 124336e227d2STejun Heo /* try to steal the timer if it exists */ 124436e227d2STejun Heo if (is_dwork) { 124536e227d2STejun Heo struct delayed_work *dwork = to_delayed_work(work); 124636e227d2STejun Heo 1247e0aecdd8STejun Heo /* 1248e0aecdd8STejun Heo * dwork->timer is irqsafe. If del_timer() fails, it's 1249e0aecdd8STejun Heo * guaranteed that the timer is not queued anywhere and not 1250e0aecdd8STejun Heo * running on the local CPU. 1251e0aecdd8STejun Heo */ 125236e227d2STejun Heo if (likely(del_timer(&dwork->timer))) 125336e227d2STejun Heo return 1; 125436e227d2STejun Heo } 125536e227d2STejun Heo 125636e227d2STejun Heo /* try to claim PENDING the normal way */ 1257bf4ede01STejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 1258bf4ede01STejun Heo return 0; 1259bf4ede01STejun Heo 126024acfb71SThomas Gleixner rcu_read_lock(); 1261bf4ede01STejun Heo /* 1262bf4ede01STejun Heo * The queueing is in progress, or it is already queued. Try to 1263bf4ede01STejun Heo * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 1264bf4ede01STejun Heo */ 1265d565ed63STejun Heo pool = get_work_pool(work); 1266d565ed63STejun Heo if (!pool) 1267bbb68dfaSTejun Heo goto fail; 1268bf4ede01STejun Heo 1269d565ed63STejun Heo spin_lock(&pool->lock); 1270bf4ede01STejun Heo /* 1271112202d9STejun Heo * work->data is guaranteed to point to pwq only while the work 1272112202d9STejun Heo * item is queued on pwq->wq, and both updating work->data to point 1273112202d9STejun Heo * to pwq on queueing and to pool on dequeueing are done under 1274112202d9STejun Heo * pwq->pool->lock. This in turn guarantees that, if work->data 1275112202d9STejun Heo * points to pwq which is associated with a locked pool, the work 12760b3dae68SLai Jiangshan * item is currently queued on that pool. 1277bf4ede01STejun Heo */ 1278112202d9STejun Heo pwq = get_work_pwq(work); 1279112202d9STejun Heo if (pwq && pwq->pool == pool) { 1280bf4ede01STejun Heo debug_work_deactivate(work); 12813aa62497SLai Jiangshan 12823aa62497SLai Jiangshan /* 128316062836STejun Heo * A delayed work item cannot be grabbed directly because 128416062836STejun Heo * it might have linked NO_COLOR work items which, if left 1285112202d9STejun Heo * on the delayed_list, will confuse pwq->nr_active 128616062836STejun Heo * management later on and cause stall. Make sure the work 128716062836STejun Heo * item is activated before grabbing. 12883aa62497SLai Jiangshan */ 12893aa62497SLai Jiangshan if (*work_data_bits(work) & WORK_STRUCT_DELAYED) 1290112202d9STejun Heo pwq_activate_delayed_work(work); 12913aa62497SLai Jiangshan 1292bf4ede01STejun Heo list_del_init(&work->entry); 12939c34a704SLai Jiangshan pwq_dec_nr_in_flight(pwq, get_work_color(work)); 129436e227d2STejun Heo 1295112202d9STejun Heo /* work->data points to pwq iff queued, point to pool */ 12964468a00fSLai Jiangshan set_work_pool_and_keep_pending(work, pool->id); 12974468a00fSLai Jiangshan 1298d565ed63STejun Heo spin_unlock(&pool->lock); 129924acfb71SThomas Gleixner rcu_read_unlock(); 130036e227d2STejun Heo return 1; 1301bf4ede01STejun Heo } 1302d565ed63STejun Heo spin_unlock(&pool->lock); 1303bbb68dfaSTejun Heo fail: 130424acfb71SThomas Gleixner rcu_read_unlock(); 1305bbb68dfaSTejun Heo local_irq_restore(*flags); 1306bbb68dfaSTejun Heo if (work_is_canceling(work)) 1307bbb68dfaSTejun Heo return -ENOENT; 1308bbb68dfaSTejun Heo cpu_relax(); 130936e227d2STejun Heo return -EAGAIN; 1310bf4ede01STejun Heo } 1311bf4ede01STejun Heo 1312bf4ede01STejun Heo /** 1313706026c2STejun Heo * insert_work - insert a work into a pool 1314112202d9STejun Heo * @pwq: pwq @work belongs to 13154690c4abSTejun Heo * @work: work to insert 13164690c4abSTejun Heo * @head: insertion point 13174690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 13184690c4abSTejun Heo * 1319112202d9STejun Heo * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to 1320706026c2STejun Heo * work_struct flags. 13214690c4abSTejun Heo * 13224690c4abSTejun Heo * CONTEXT: 1323d565ed63STejun Heo * spin_lock_irq(pool->lock). 1324365970a1SDavid Howells */ 1325112202d9STejun Heo static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, 1326112202d9STejun Heo struct list_head *head, unsigned int extra_flags) 1327b89deed3SOleg Nesterov { 1328112202d9STejun Heo struct worker_pool *pool = pwq->pool; 1329e1d8aa9fSFrederic Weisbecker 13304690c4abSTejun Heo /* we own @work, set data and link */ 1331112202d9STejun Heo set_work_pwq(work, pwq, extra_flags); 13321a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 13338864b4e5STejun Heo get_pwq(pwq); 1334e22bee78STejun Heo 1335e22bee78STejun Heo /* 1336c5aa87bbSTejun Heo * Ensure either wq_worker_sleeping() sees the above 1337c5aa87bbSTejun Heo * list_add_tail() or we see zero nr_running to avoid workers lying 1338c5aa87bbSTejun Heo * around lazily while there are works to be processed. 1339e22bee78STejun Heo */ 1340e22bee78STejun Heo smp_mb(); 1341e22bee78STejun Heo 134263d95a91STejun Heo if (__need_more_worker(pool)) 134363d95a91STejun Heo wake_up_worker(pool); 1344b89deed3SOleg Nesterov } 1345b89deed3SOleg Nesterov 1346c8efcc25STejun Heo /* 1347c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 13488d03ecfeSTejun Heo * same workqueue. 1349c8efcc25STejun Heo */ 1350c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 1351c8efcc25STejun Heo { 1352c8efcc25STejun Heo struct worker *worker; 1353c8efcc25STejun Heo 13548d03ecfeSTejun Heo worker = current_wq_worker(); 1355c8efcc25STejun Heo /* 1356bf393fd4SBart Van Assche * Return %true iff I'm a worker executing a work item on @wq. If 13578d03ecfeSTejun Heo * I'm @worker, it's safe to dereference it without locking. 1358c8efcc25STejun Heo */ 1359112202d9STejun Heo return worker && worker->current_pwq->wq == wq; 1360c8efcc25STejun Heo } 1361c8efcc25STejun Heo 1362ef557180SMike Galbraith /* 1363ef557180SMike Galbraith * When queueing an unbound work item to a wq, prefer local CPU if allowed 1364ef557180SMike Galbraith * by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to 1365ef557180SMike Galbraith * avoid perturbing sensitive tasks. 1366ef557180SMike Galbraith */ 1367ef557180SMike Galbraith static int wq_select_unbound_cpu(int cpu) 1368ef557180SMike Galbraith { 1369f303fccbSTejun Heo static bool printed_dbg_warning; 1370ef557180SMike Galbraith int new_cpu; 1371ef557180SMike Galbraith 1372f303fccbSTejun Heo if (likely(!wq_debug_force_rr_cpu)) { 1373ef557180SMike Galbraith if (cpumask_test_cpu(cpu, wq_unbound_cpumask)) 1374ef557180SMike Galbraith return cpu; 1375f303fccbSTejun Heo } else if (!printed_dbg_warning) { 1376f303fccbSTejun Heo pr_warn("workqueue: round-robin CPU selection forced, expect performance impact\n"); 1377f303fccbSTejun Heo printed_dbg_warning = true; 1378f303fccbSTejun Heo } 1379f303fccbSTejun Heo 1380ef557180SMike Galbraith if (cpumask_empty(wq_unbound_cpumask)) 1381ef557180SMike Galbraith return cpu; 1382ef557180SMike Galbraith 1383ef557180SMike Galbraith new_cpu = __this_cpu_read(wq_rr_cpu_last); 1384ef557180SMike Galbraith new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask); 1385ef557180SMike Galbraith if (unlikely(new_cpu >= nr_cpu_ids)) { 1386ef557180SMike Galbraith new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask); 1387ef557180SMike Galbraith if (unlikely(new_cpu >= nr_cpu_ids)) 1388ef557180SMike Galbraith return cpu; 1389ef557180SMike Galbraith } 1390ef557180SMike Galbraith __this_cpu_write(wq_rr_cpu_last, new_cpu); 1391ef557180SMike Galbraith 1392ef557180SMike Galbraith return new_cpu; 1393ef557180SMike Galbraith } 1394ef557180SMike Galbraith 1395d84ff051STejun Heo static void __queue_work(int cpu, struct workqueue_struct *wq, 13961da177e4SLinus Torvalds struct work_struct *work) 13971da177e4SLinus Torvalds { 1398112202d9STejun Heo struct pool_workqueue *pwq; 1399c9178087STejun Heo struct worker_pool *last_pool; 14001e19ffc6STejun Heo struct list_head *worklist; 14018a2e8e5dSTejun Heo unsigned int work_flags; 1402b75cac93SJoonsoo Kim unsigned int req_cpu = cpu; 14038930cabaSTejun Heo 14048930cabaSTejun Heo /* 14058930cabaSTejun Heo * While a work item is PENDING && off queue, a task trying to 14068930cabaSTejun Heo * steal the PENDING will busy-loop waiting for it to either get 14078930cabaSTejun Heo * queued or lose PENDING. Grabbing PENDING and queueing should 14088930cabaSTejun Heo * happen with IRQ disabled. 14098930cabaSTejun Heo */ 14108e8eb730SFrederic Weisbecker lockdep_assert_irqs_disabled(); 14111da177e4SLinus Torvalds 1412dc186ad7SThomas Gleixner debug_work_activate(work); 14131e19ffc6STejun Heo 14149ef28a73SLi Bin /* if draining, only works from the same workqueue are allowed */ 1415618b01ebSTejun Heo if (unlikely(wq->flags & __WQ_DRAINING) && 1416c8efcc25STejun Heo WARN_ON_ONCE(!is_chained_work(wq))) 1417e41e704bSTejun Heo return; 141824acfb71SThomas Gleixner rcu_read_lock(); 14199e8cd2f5STejun Heo retry: 1420df2d5ae4STejun Heo if (req_cpu == WORK_CPU_UNBOUND) 1421ef557180SMike Galbraith cpu = wq_select_unbound_cpu(raw_smp_processor_id()); 1422df2d5ae4STejun Heo 1423df2d5ae4STejun Heo /* pwq which will be used unless @work is executing elsewhere */ 1424df2d5ae4STejun Heo if (!(wq->flags & WQ_UNBOUND)) 1425c9178087STejun Heo pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); 1426df2d5ae4STejun Heo else 1427df2d5ae4STejun Heo pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); 1428f3421797STejun Heo 142918aa9effSTejun Heo /* 1430c9178087STejun Heo * If @work was previously on a different pool, it might still be 1431c9178087STejun Heo * running there, in which case the work needs to be queued on that 1432c9178087STejun Heo * pool to guarantee non-reentrancy. 143318aa9effSTejun Heo */ 1434c9e7cf27STejun Heo last_pool = get_work_pool(work); 1435112202d9STejun Heo if (last_pool && last_pool != pwq->pool) { 143618aa9effSTejun Heo struct worker *worker; 143718aa9effSTejun Heo 1438d565ed63STejun Heo spin_lock(&last_pool->lock); 143918aa9effSTejun Heo 1440c9e7cf27STejun Heo worker = find_worker_executing_work(last_pool, work); 144118aa9effSTejun Heo 1442112202d9STejun Heo if (worker && worker->current_pwq->wq == wq) { 1443c9178087STejun Heo pwq = worker->current_pwq; 14448594fadeSLai Jiangshan } else { 144518aa9effSTejun Heo /* meh... not running there, queue here */ 1446d565ed63STejun Heo spin_unlock(&last_pool->lock); 1447112202d9STejun Heo spin_lock(&pwq->pool->lock); 144818aa9effSTejun Heo } 14498930cabaSTejun Heo } else { 1450112202d9STejun Heo spin_lock(&pwq->pool->lock); 14518930cabaSTejun Heo } 1452502ca9d8STejun Heo 14539e8cd2f5STejun Heo /* 14549e8cd2f5STejun Heo * pwq is determined and locked. For unbound pools, we could have 14559e8cd2f5STejun Heo * raced with pwq release and it could already be dead. If its 14569e8cd2f5STejun Heo * refcnt is zero, repeat pwq selection. Note that pwqs never die 1457df2d5ae4STejun Heo * without another pwq replacing it in the numa_pwq_tbl or while 1458df2d5ae4STejun Heo * work items are executing on it, so the retrying is guaranteed to 14599e8cd2f5STejun Heo * make forward-progress. 14609e8cd2f5STejun Heo */ 14619e8cd2f5STejun Heo if (unlikely(!pwq->refcnt)) { 14629e8cd2f5STejun Heo if (wq->flags & WQ_UNBOUND) { 14639e8cd2f5STejun Heo spin_unlock(&pwq->pool->lock); 14649e8cd2f5STejun Heo cpu_relax(); 14659e8cd2f5STejun Heo goto retry; 14669e8cd2f5STejun Heo } 14679e8cd2f5STejun Heo /* oops */ 14689e8cd2f5STejun Heo WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", 14699e8cd2f5STejun Heo wq->name, cpu); 14709e8cd2f5STejun Heo } 14719e8cd2f5STejun Heo 1472112202d9STejun Heo /* pwq determined, queue */ 1473112202d9STejun Heo trace_workqueue_queue_work(req_cpu, pwq, work); 1474502ca9d8STejun Heo 147524acfb71SThomas Gleixner if (WARN_ON(!list_empty(&work->entry))) 147624acfb71SThomas Gleixner goto out; 14771e19ffc6STejun Heo 1478112202d9STejun Heo pwq->nr_in_flight[pwq->work_color]++; 1479112202d9STejun Heo work_flags = work_color_to_flags(pwq->work_color); 14801e19ffc6STejun Heo 1481112202d9STejun Heo if (likely(pwq->nr_active < pwq->max_active)) { 1482cdadf009STejun Heo trace_workqueue_activate_work(work); 1483112202d9STejun Heo pwq->nr_active++; 1484112202d9STejun Heo worklist = &pwq->pool->worklist; 148582607adcSTejun Heo if (list_empty(worklist)) 148682607adcSTejun Heo pwq->pool->watchdog_ts = jiffies; 14878a2e8e5dSTejun Heo } else { 14888a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 1489112202d9STejun Heo worklist = &pwq->delayed_works; 14908a2e8e5dSTejun Heo } 14911e19ffc6STejun Heo 1492112202d9STejun Heo insert_work(pwq, work, worklist, work_flags); 14931e19ffc6STejun Heo 149424acfb71SThomas Gleixner out: 1495112202d9STejun Heo spin_unlock(&pwq->pool->lock); 149624acfb71SThomas Gleixner rcu_read_unlock(); 14971da177e4SLinus Torvalds } 14981da177e4SLinus Torvalds 14990fcb78c2SRolf Eike Beer /** 1500c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1501c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1502c1a220e7SZhang Rui * @wq: workqueue to use 1503c1a220e7SZhang Rui * @work: work to queue 1504c1a220e7SZhang Rui * 1505c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1506c1a220e7SZhang Rui * can't go away. 1507d185af30SYacine Belkadi * 1508d185af30SYacine Belkadi * Return: %false if @work was already on a queue, %true otherwise. 1509c1a220e7SZhang Rui */ 1510d4283e93STejun Heo bool queue_work_on(int cpu, struct workqueue_struct *wq, 1511d4283e93STejun Heo struct work_struct *work) 1512c1a220e7SZhang Rui { 1513d4283e93STejun Heo bool ret = false; 15148930cabaSTejun Heo unsigned long flags; 15158930cabaSTejun Heo 15168930cabaSTejun Heo local_irq_save(flags); 1517c1a220e7SZhang Rui 151822df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 15194690c4abSTejun Heo __queue_work(cpu, wq, work); 1520d4283e93STejun Heo ret = true; 1521c1a220e7SZhang Rui } 15228930cabaSTejun Heo 15238930cabaSTejun Heo local_irq_restore(flags); 1524c1a220e7SZhang Rui return ret; 1525c1a220e7SZhang Rui } 1526ad7b1f84SMarc Dionne EXPORT_SYMBOL(queue_work_on); 1527c1a220e7SZhang Rui 15288204e0c1SAlexander Duyck /** 15298204e0c1SAlexander Duyck * workqueue_select_cpu_near - Select a CPU based on NUMA node 15308204e0c1SAlexander Duyck * @node: NUMA node ID that we want to select a CPU from 15318204e0c1SAlexander Duyck * 15328204e0c1SAlexander Duyck * This function will attempt to find a "random" cpu available on a given 15338204e0c1SAlexander Duyck * node. If there are no CPUs available on the given node it will return 15348204e0c1SAlexander Duyck * WORK_CPU_UNBOUND indicating that we should just schedule to any 15358204e0c1SAlexander Duyck * available CPU if we need to schedule this work. 15368204e0c1SAlexander Duyck */ 15378204e0c1SAlexander Duyck static int workqueue_select_cpu_near(int node) 15388204e0c1SAlexander Duyck { 15398204e0c1SAlexander Duyck int cpu; 15408204e0c1SAlexander Duyck 15418204e0c1SAlexander Duyck /* No point in doing this if NUMA isn't enabled for workqueues */ 15428204e0c1SAlexander Duyck if (!wq_numa_enabled) 15438204e0c1SAlexander Duyck return WORK_CPU_UNBOUND; 15448204e0c1SAlexander Duyck 15458204e0c1SAlexander Duyck /* Delay binding to CPU if node is not valid or online */ 15468204e0c1SAlexander Duyck if (node < 0 || node >= MAX_NUMNODES || !node_online(node)) 15478204e0c1SAlexander Duyck return WORK_CPU_UNBOUND; 15488204e0c1SAlexander Duyck 15498204e0c1SAlexander Duyck /* Use local node/cpu if we are already there */ 15508204e0c1SAlexander Duyck cpu = raw_smp_processor_id(); 15518204e0c1SAlexander Duyck if (node == cpu_to_node(cpu)) 15528204e0c1SAlexander Duyck return cpu; 15538204e0c1SAlexander Duyck 15548204e0c1SAlexander Duyck /* Use "random" otherwise know as "first" online CPU of node */ 15558204e0c1SAlexander Duyck cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); 15568204e0c1SAlexander Duyck 15578204e0c1SAlexander Duyck /* If CPU is valid return that, otherwise just defer */ 15588204e0c1SAlexander Duyck return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND; 15598204e0c1SAlexander Duyck } 15608204e0c1SAlexander Duyck 15618204e0c1SAlexander Duyck /** 15628204e0c1SAlexander Duyck * queue_work_node - queue work on a "random" cpu for a given NUMA node 15638204e0c1SAlexander Duyck * @node: NUMA node that we are targeting the work for 15648204e0c1SAlexander Duyck * @wq: workqueue to use 15658204e0c1SAlexander Duyck * @work: work to queue 15668204e0c1SAlexander Duyck * 15678204e0c1SAlexander Duyck * We queue the work to a "random" CPU within a given NUMA node. The basic 15688204e0c1SAlexander Duyck * idea here is to provide a way to somehow associate work with a given 15698204e0c1SAlexander Duyck * NUMA node. 15708204e0c1SAlexander Duyck * 15718204e0c1SAlexander Duyck * This function will only make a best effort attempt at getting this onto 15728204e0c1SAlexander Duyck * the right NUMA node. If no node is requested or the requested node is 15738204e0c1SAlexander Duyck * offline then we just fall back to standard queue_work behavior. 15748204e0c1SAlexander Duyck * 15758204e0c1SAlexander Duyck * Currently the "random" CPU ends up being the first available CPU in the 15768204e0c1SAlexander Duyck * intersection of cpu_online_mask and the cpumask of the node, unless we 15778204e0c1SAlexander Duyck * are running on the node. In that case we just use the current CPU. 15788204e0c1SAlexander Duyck * 15798204e0c1SAlexander Duyck * Return: %false if @work was already on a queue, %true otherwise. 15808204e0c1SAlexander Duyck */ 15818204e0c1SAlexander Duyck bool queue_work_node(int node, struct workqueue_struct *wq, 15828204e0c1SAlexander Duyck struct work_struct *work) 15838204e0c1SAlexander Duyck { 15848204e0c1SAlexander Duyck unsigned long flags; 15858204e0c1SAlexander Duyck bool ret = false; 15868204e0c1SAlexander Duyck 15878204e0c1SAlexander Duyck /* 15888204e0c1SAlexander Duyck * This current implementation is specific to unbound workqueues. 15898204e0c1SAlexander Duyck * Specifically we only return the first available CPU for a given 15908204e0c1SAlexander Duyck * node instead of cycling through individual CPUs within the node. 15918204e0c1SAlexander Duyck * 15928204e0c1SAlexander Duyck * If this is used with a per-cpu workqueue then the logic in 15938204e0c1SAlexander Duyck * workqueue_select_cpu_near would need to be updated to allow for 15948204e0c1SAlexander Duyck * some round robin type logic. 15958204e0c1SAlexander Duyck */ 15968204e0c1SAlexander Duyck WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)); 15978204e0c1SAlexander Duyck 15988204e0c1SAlexander Duyck local_irq_save(flags); 15998204e0c1SAlexander Duyck 16008204e0c1SAlexander Duyck if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 16018204e0c1SAlexander Duyck int cpu = workqueue_select_cpu_near(node); 16028204e0c1SAlexander Duyck 16038204e0c1SAlexander Duyck __queue_work(cpu, wq, work); 16048204e0c1SAlexander Duyck ret = true; 16058204e0c1SAlexander Duyck } 16068204e0c1SAlexander Duyck 16078204e0c1SAlexander Duyck local_irq_restore(flags); 16088204e0c1SAlexander Duyck return ret; 16098204e0c1SAlexander Duyck } 16108204e0c1SAlexander Duyck EXPORT_SYMBOL_GPL(queue_work_node); 16118204e0c1SAlexander Duyck 16128c20feb6SKees Cook void delayed_work_timer_fn(struct timer_list *t) 16131da177e4SLinus Torvalds { 16148c20feb6SKees Cook struct delayed_work *dwork = from_timer(dwork, t, timer); 16151da177e4SLinus Torvalds 1616e0aecdd8STejun Heo /* should have been called from irqsafe timer with irq already off */ 161760c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 16181da177e4SLinus Torvalds } 16191438ade5SKonstantin Khlebnikov EXPORT_SYMBOL(delayed_work_timer_fn); 16201da177e4SLinus Torvalds 16217beb2edfSTejun Heo static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 162252bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 16231da177e4SLinus Torvalds { 16247beb2edfSTejun Heo struct timer_list *timer = &dwork->timer; 16257beb2edfSTejun Heo struct work_struct *work = &dwork->work; 16261da177e4SLinus Torvalds 1627637fdbaeSTejun Heo WARN_ON_ONCE(!wq); 1628841b86f3SKees Cook WARN_ON_ONCE(timer->function != delayed_work_timer_fn); 1629fc4b514fSTejun Heo WARN_ON_ONCE(timer_pending(timer)); 1630fc4b514fSTejun Heo WARN_ON_ONCE(!list_empty(&work->entry)); 16317beb2edfSTejun Heo 16328852aac2STejun Heo /* 16338852aac2STejun Heo * If @delay is 0, queue @dwork->work immediately. This is for 16348852aac2STejun Heo * both optimization and correctness. The earliest @timer can 16358852aac2STejun Heo * expire is on the closest next tick and delayed_work users depend 16368852aac2STejun Heo * on that there's no such delay when @delay is 0. 16378852aac2STejun Heo */ 16388852aac2STejun Heo if (!delay) { 16398852aac2STejun Heo __queue_work(cpu, wq, &dwork->work); 16408852aac2STejun Heo return; 16418852aac2STejun Heo } 16428852aac2STejun Heo 164360c057bcSLai Jiangshan dwork->wq = wq; 16441265057fSTejun Heo dwork->cpu = cpu; 16457beb2edfSTejun Heo timer->expires = jiffies + delay; 16467beb2edfSTejun Heo 1647041bd12eSTejun Heo if (unlikely(cpu != WORK_CPU_UNBOUND)) 16487beb2edfSTejun Heo add_timer_on(timer, cpu); 1649041bd12eSTejun Heo else 1650041bd12eSTejun Heo add_timer(timer); 16517beb2edfSTejun Heo } 16521da177e4SLinus Torvalds 16530fcb78c2SRolf Eike Beer /** 16540fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 16550fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 16560fcb78c2SRolf Eike Beer * @wq: workqueue to use 1657af9997e4SRandy Dunlap * @dwork: work to queue 16580fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 16590fcb78c2SRolf Eike Beer * 1660d185af30SYacine Belkadi * Return: %false if @work was already on a queue, %true otherwise. If 1661715f1300STejun Heo * @delay is zero and @dwork is idle, it will be scheduled for immediate 1662715f1300STejun Heo * execution. 16630fcb78c2SRolf Eike Beer */ 1664d4283e93STejun Heo bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 166552bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 16667a6bc1cdSVenkatesh Pallipadi { 166752bad64dSDavid Howells struct work_struct *work = &dwork->work; 1668d4283e93STejun Heo bool ret = false; 16698930cabaSTejun Heo unsigned long flags; 16708930cabaSTejun Heo 16718930cabaSTejun Heo /* read the comment in __queue_work() */ 16728930cabaSTejun Heo local_irq_save(flags); 16737a6bc1cdSVenkatesh Pallipadi 167422df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 16757beb2edfSTejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 1676d4283e93STejun Heo ret = true; 16777a6bc1cdSVenkatesh Pallipadi } 16788930cabaSTejun Heo 16798930cabaSTejun Heo local_irq_restore(flags); 16807a6bc1cdSVenkatesh Pallipadi return ret; 16817a6bc1cdSVenkatesh Pallipadi } 1682ad7b1f84SMarc Dionne EXPORT_SYMBOL(queue_delayed_work_on); 16831da177e4SLinus Torvalds 1684c8e55f36STejun Heo /** 16858376fe22STejun Heo * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 16868376fe22STejun Heo * @cpu: CPU number to execute work on 16878376fe22STejun Heo * @wq: workqueue to use 16888376fe22STejun Heo * @dwork: work to queue 16898376fe22STejun Heo * @delay: number of jiffies to wait before queueing 16908376fe22STejun Heo * 16918376fe22STejun Heo * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 16928376fe22STejun Heo * modify @dwork's timer so that it expires after @delay. If @delay is 16938376fe22STejun Heo * zero, @work is guaranteed to be scheduled immediately regardless of its 16948376fe22STejun Heo * current state. 16958376fe22STejun Heo * 1696d185af30SYacine Belkadi * Return: %false if @dwork was idle and queued, %true if @dwork was 16978376fe22STejun Heo * pending and its timer was modified. 16988376fe22STejun Heo * 1699e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 17008376fe22STejun Heo * See try_to_grab_pending() for details. 17018376fe22STejun Heo */ 17028376fe22STejun Heo bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 17038376fe22STejun Heo struct delayed_work *dwork, unsigned long delay) 17048376fe22STejun Heo { 17058376fe22STejun Heo unsigned long flags; 17068376fe22STejun Heo int ret; 17078376fe22STejun Heo 17088376fe22STejun Heo do { 17098376fe22STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 17108376fe22STejun Heo } while (unlikely(ret == -EAGAIN)); 17118376fe22STejun Heo 17128376fe22STejun Heo if (likely(ret >= 0)) { 17138376fe22STejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 17148376fe22STejun Heo local_irq_restore(flags); 17158376fe22STejun Heo } 17168376fe22STejun Heo 17178376fe22STejun Heo /* -ENOENT from try_to_grab_pending() becomes %true */ 17188376fe22STejun Heo return ret; 17198376fe22STejun Heo } 17208376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work_on); 17218376fe22STejun Heo 172205f0fe6bSTejun Heo static void rcu_work_rcufn(struct rcu_head *rcu) 172305f0fe6bSTejun Heo { 172405f0fe6bSTejun Heo struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu); 172505f0fe6bSTejun Heo 172605f0fe6bSTejun Heo /* read the comment in __queue_work() */ 172705f0fe6bSTejun Heo local_irq_disable(); 172805f0fe6bSTejun Heo __queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work); 172905f0fe6bSTejun Heo local_irq_enable(); 173005f0fe6bSTejun Heo } 173105f0fe6bSTejun Heo 173205f0fe6bSTejun Heo /** 173305f0fe6bSTejun Heo * queue_rcu_work - queue work after a RCU grace period 173405f0fe6bSTejun Heo * @wq: workqueue to use 173505f0fe6bSTejun Heo * @rwork: work to queue 173605f0fe6bSTejun Heo * 173705f0fe6bSTejun Heo * Return: %false if @rwork was already pending, %true otherwise. Note 173805f0fe6bSTejun Heo * that a full RCU grace period is guaranteed only after a %true return. 1739bf393fd4SBart Van Assche * While @rwork is guaranteed to be executed after a %false return, the 174005f0fe6bSTejun Heo * execution may happen before a full RCU grace period has passed. 174105f0fe6bSTejun Heo */ 174205f0fe6bSTejun Heo bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork) 174305f0fe6bSTejun Heo { 174405f0fe6bSTejun Heo struct work_struct *work = &rwork->work; 174505f0fe6bSTejun Heo 174605f0fe6bSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 174705f0fe6bSTejun Heo rwork->wq = wq; 174805f0fe6bSTejun Heo call_rcu(&rwork->rcu, rcu_work_rcufn); 174905f0fe6bSTejun Heo return true; 175005f0fe6bSTejun Heo } 175105f0fe6bSTejun Heo 175205f0fe6bSTejun Heo return false; 175305f0fe6bSTejun Heo } 175405f0fe6bSTejun Heo EXPORT_SYMBOL(queue_rcu_work); 175505f0fe6bSTejun Heo 17568376fe22STejun Heo /** 1757c8e55f36STejun Heo * worker_enter_idle - enter idle state 1758c8e55f36STejun Heo * @worker: worker which is entering idle state 1759c8e55f36STejun Heo * 1760c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1761c8e55f36STejun Heo * necessary. 1762c8e55f36STejun Heo * 1763c8e55f36STejun Heo * LOCKING: 1764d565ed63STejun Heo * spin_lock_irq(pool->lock). 1765c8e55f36STejun Heo */ 1766c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 17671da177e4SLinus Torvalds { 1768bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1769c8e55f36STejun Heo 17706183c009STejun Heo if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || 17716183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->entry) && 17726183c009STejun Heo (worker->hentry.next || worker->hentry.pprev))) 17736183c009STejun Heo return; 1774c8e55f36STejun Heo 1775051e1850SLai Jiangshan /* can't use worker_set_flags(), also called from create_worker() */ 1776cb444766STejun Heo worker->flags |= WORKER_IDLE; 1777bd7bdd43STejun Heo pool->nr_idle++; 1778e22bee78STejun Heo worker->last_active = jiffies; 1779c8e55f36STejun Heo 1780c8e55f36STejun Heo /* idle_list is LIFO */ 1781bd7bdd43STejun Heo list_add(&worker->entry, &pool->idle_list); 1782db7bccf4STejun Heo 178363d95a91STejun Heo if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 1784628c78e7STejun Heo mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 1785cb444766STejun Heo 1786544ecf31STejun Heo /* 1787e8b3f8dbSLai Jiangshan * Sanity check nr_running. Because unbind_workers() releases 1788d565ed63STejun Heo * pool->lock between setting %WORKER_UNBOUND and zapping 1789628c78e7STejun Heo * nr_running, the warning may trigger spuriously. Check iff 1790628c78e7STejun Heo * unbind is not in progress. 1791544ecf31STejun Heo */ 179224647570STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 1793bd7bdd43STejun Heo pool->nr_workers == pool->nr_idle && 1794e19e397aSTejun Heo atomic_read(&pool->nr_running)); 1795c8e55f36STejun Heo } 1796c8e55f36STejun Heo 1797c8e55f36STejun Heo /** 1798c8e55f36STejun Heo * worker_leave_idle - leave idle state 1799c8e55f36STejun Heo * @worker: worker which is leaving idle state 1800c8e55f36STejun Heo * 1801c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1802c8e55f36STejun Heo * 1803c8e55f36STejun Heo * LOCKING: 1804d565ed63STejun Heo * spin_lock_irq(pool->lock). 1805c8e55f36STejun Heo */ 1806c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1807c8e55f36STejun Heo { 1808bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1809c8e55f36STejun Heo 18106183c009STejun Heo if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) 18116183c009STejun Heo return; 1812d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1813bd7bdd43STejun Heo pool->nr_idle--; 1814c8e55f36STejun Heo list_del_init(&worker->entry); 1815c8e55f36STejun Heo } 1816c8e55f36STejun Heo 1817f7537df5SLai Jiangshan static struct worker *alloc_worker(int node) 1818c34056a3STejun Heo { 1819c34056a3STejun Heo struct worker *worker; 1820c34056a3STejun Heo 1821f7537df5SLai Jiangshan worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node); 1822c8e55f36STejun Heo if (worker) { 1823c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1824affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1825da028469SLai Jiangshan INIT_LIST_HEAD(&worker->node); 1826e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1827e22bee78STejun Heo worker->flags = WORKER_PREP; 1828c8e55f36STejun Heo } 1829c34056a3STejun Heo return worker; 1830c34056a3STejun Heo } 1831c34056a3STejun Heo 1832c34056a3STejun Heo /** 18334736cbf7SLai Jiangshan * worker_attach_to_pool() - attach a worker to a pool 18344736cbf7SLai Jiangshan * @worker: worker to be attached 18354736cbf7SLai Jiangshan * @pool: the target pool 18364736cbf7SLai Jiangshan * 18374736cbf7SLai Jiangshan * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and 18384736cbf7SLai Jiangshan * cpu-binding of @worker are kept coordinated with the pool across 18394736cbf7SLai Jiangshan * cpu-[un]hotplugs. 18404736cbf7SLai Jiangshan */ 18414736cbf7SLai Jiangshan static void worker_attach_to_pool(struct worker *worker, 18424736cbf7SLai Jiangshan struct worker_pool *pool) 18434736cbf7SLai Jiangshan { 18441258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 18454736cbf7SLai Jiangshan 18464736cbf7SLai Jiangshan /* 18474736cbf7SLai Jiangshan * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any 18484736cbf7SLai Jiangshan * online CPUs. It'll be re-applied when any of the CPUs come up. 18494736cbf7SLai Jiangshan */ 18504736cbf7SLai Jiangshan set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); 18514736cbf7SLai Jiangshan 18524736cbf7SLai Jiangshan /* 18531258fae7STejun Heo * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains 18541258fae7STejun Heo * stable across this function. See the comments above the flag 18551258fae7STejun Heo * definition for details. 18564736cbf7SLai Jiangshan */ 18574736cbf7SLai Jiangshan if (pool->flags & POOL_DISASSOCIATED) 18584736cbf7SLai Jiangshan worker->flags |= WORKER_UNBOUND; 18594736cbf7SLai Jiangshan 18604736cbf7SLai Jiangshan list_add_tail(&worker->node, &pool->workers); 1861a2d812a2STejun Heo worker->pool = pool; 18624736cbf7SLai Jiangshan 18631258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 18644736cbf7SLai Jiangshan } 18654736cbf7SLai Jiangshan 18664736cbf7SLai Jiangshan /** 186760f5a4bcSLai Jiangshan * worker_detach_from_pool() - detach a worker from its pool 186860f5a4bcSLai Jiangshan * @worker: worker which is attached to its pool 186960f5a4bcSLai Jiangshan * 18704736cbf7SLai Jiangshan * Undo the attaching which had been done in worker_attach_to_pool(). The 18714736cbf7SLai Jiangshan * caller worker shouldn't access to the pool after detached except it has 18724736cbf7SLai Jiangshan * other reference to the pool. 187360f5a4bcSLai Jiangshan */ 1874a2d812a2STejun Heo static void worker_detach_from_pool(struct worker *worker) 187560f5a4bcSLai Jiangshan { 1876a2d812a2STejun Heo struct worker_pool *pool = worker->pool; 187760f5a4bcSLai Jiangshan struct completion *detach_completion = NULL; 187860f5a4bcSLai Jiangshan 18791258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 1880a2d812a2STejun Heo 1881da028469SLai Jiangshan list_del(&worker->node); 1882a2d812a2STejun Heo worker->pool = NULL; 1883a2d812a2STejun Heo 1884da028469SLai Jiangshan if (list_empty(&pool->workers)) 188560f5a4bcSLai Jiangshan detach_completion = pool->detach_completion; 18861258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 188760f5a4bcSLai Jiangshan 1888b62c0751SLai Jiangshan /* clear leftover flags without pool->lock after it is detached */ 1889b62c0751SLai Jiangshan worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND); 1890b62c0751SLai Jiangshan 189160f5a4bcSLai Jiangshan if (detach_completion) 189260f5a4bcSLai Jiangshan complete(detach_completion); 189360f5a4bcSLai Jiangshan } 189460f5a4bcSLai Jiangshan 189560f5a4bcSLai Jiangshan /** 1896c34056a3STejun Heo * create_worker - create a new workqueue worker 189763d95a91STejun Heo * @pool: pool the new worker will belong to 1898c34056a3STejun Heo * 1899051e1850SLai Jiangshan * Create and start a new worker which is attached to @pool. 1900c34056a3STejun Heo * 1901c34056a3STejun Heo * CONTEXT: 1902c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1903c34056a3STejun Heo * 1904d185af30SYacine Belkadi * Return: 1905c34056a3STejun Heo * Pointer to the newly created worker. 1906c34056a3STejun Heo */ 1907bc2ae0f5STejun Heo static struct worker *create_worker(struct worker_pool *pool) 1908c34056a3STejun Heo { 1909c34056a3STejun Heo struct worker *worker = NULL; 1910f3421797STejun Heo int id = -1; 1911e3c916a4STejun Heo char id_buf[16]; 1912c34056a3STejun Heo 19137cda9aaeSLai Jiangshan /* ID is needed to determine kthread name */ 19147cda9aaeSLai Jiangshan id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL); 1915822d8405STejun Heo if (id < 0) 1916c34056a3STejun Heo goto fail; 1917c34056a3STejun Heo 1918f7537df5SLai Jiangshan worker = alloc_worker(pool->node); 1919c34056a3STejun Heo if (!worker) 1920c34056a3STejun Heo goto fail; 1921c34056a3STejun Heo 1922c34056a3STejun Heo worker->id = id; 1923c34056a3STejun Heo 192429c91e99STejun Heo if (pool->cpu >= 0) 1925e3c916a4STejun Heo snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, 1926e3c916a4STejun Heo pool->attrs->nice < 0 ? "H" : ""); 1927f3421797STejun Heo else 1928e3c916a4STejun Heo snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); 1929e3c916a4STejun Heo 1930f3f90ad4STejun Heo worker->task = kthread_create_on_node(worker_thread, worker, pool->node, 1931e3c916a4STejun Heo "kworker/%s", id_buf); 1932c34056a3STejun Heo if (IS_ERR(worker->task)) 1933c34056a3STejun Heo goto fail; 1934c34056a3STejun Heo 193591151228SOleg Nesterov set_user_nice(worker->task, pool->attrs->nice); 193625834c73SPeter Zijlstra kthread_bind_mask(worker->task, pool->attrs->cpumask); 193791151228SOleg Nesterov 1938da028469SLai Jiangshan /* successful, attach the worker to the pool */ 19394736cbf7SLai Jiangshan worker_attach_to_pool(worker, pool); 1940822d8405STejun Heo 1941051e1850SLai Jiangshan /* start the newly created worker */ 1942051e1850SLai Jiangshan spin_lock_irq(&pool->lock); 1943051e1850SLai Jiangshan worker->pool->nr_workers++; 1944051e1850SLai Jiangshan worker_enter_idle(worker); 1945051e1850SLai Jiangshan wake_up_process(worker->task); 1946051e1850SLai Jiangshan spin_unlock_irq(&pool->lock); 1947051e1850SLai Jiangshan 1948c34056a3STejun Heo return worker; 1949822d8405STejun Heo 1950c34056a3STejun Heo fail: 19519625ab17SLai Jiangshan if (id >= 0) 19527cda9aaeSLai Jiangshan ida_simple_remove(&pool->worker_ida, id); 1953c34056a3STejun Heo kfree(worker); 1954c34056a3STejun Heo return NULL; 1955c34056a3STejun Heo } 1956c34056a3STejun Heo 1957c34056a3STejun Heo /** 1958c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1959c34056a3STejun Heo * @worker: worker to be destroyed 1960c34056a3STejun Heo * 196173eb7fe7SLai Jiangshan * Destroy @worker and adjust @pool stats accordingly. The worker should 196273eb7fe7SLai Jiangshan * be idle. 1963c8e55f36STejun Heo * 1964c8e55f36STejun Heo * CONTEXT: 196560f5a4bcSLai Jiangshan * spin_lock_irq(pool->lock). 1966c34056a3STejun Heo */ 1967c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1968c34056a3STejun Heo { 1969bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1970c34056a3STejun Heo 1971cd549687STejun Heo lockdep_assert_held(&pool->lock); 1972cd549687STejun Heo 1973c34056a3STejun Heo /* sanity check frenzy */ 19746183c009STejun Heo if (WARN_ON(worker->current_work) || 197573eb7fe7SLai Jiangshan WARN_ON(!list_empty(&worker->scheduled)) || 197673eb7fe7SLai Jiangshan WARN_ON(!(worker->flags & WORKER_IDLE))) 19776183c009STejun Heo return; 1978c34056a3STejun Heo 1979bd7bdd43STejun Heo pool->nr_workers--; 1980bd7bdd43STejun Heo pool->nr_idle--; 1981c8e55f36STejun Heo 1982c8e55f36STejun Heo list_del_init(&worker->entry); 1983cb444766STejun Heo worker->flags |= WORKER_DIE; 198460f5a4bcSLai Jiangshan wake_up_process(worker->task); 1985c34056a3STejun Heo } 1986c34056a3STejun Heo 198732a6c723SKees Cook static void idle_worker_timeout(struct timer_list *t) 1988e22bee78STejun Heo { 198932a6c723SKees Cook struct worker_pool *pool = from_timer(pool, t, idle_timer); 1990e22bee78STejun Heo 1991d565ed63STejun Heo spin_lock_irq(&pool->lock); 1992e22bee78STejun Heo 19933347fc9fSLai Jiangshan while (too_many_workers(pool)) { 1994e22bee78STejun Heo struct worker *worker; 1995e22bee78STejun Heo unsigned long expires; 1996e22bee78STejun Heo 1997e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 199863d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 1999e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 2000e22bee78STejun Heo 20013347fc9fSLai Jiangshan if (time_before(jiffies, expires)) { 200263d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 20033347fc9fSLai Jiangshan break; 2004e22bee78STejun Heo } 20053347fc9fSLai Jiangshan 20063347fc9fSLai Jiangshan destroy_worker(worker); 2007e22bee78STejun Heo } 2008e22bee78STejun Heo 2009d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2010e22bee78STejun Heo } 2011e22bee78STejun Heo 2012493a1724STejun Heo static void send_mayday(struct work_struct *work) 2013e22bee78STejun Heo { 2014112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2015112202d9STejun Heo struct workqueue_struct *wq = pwq->wq; 2016493a1724STejun Heo 20172e109a28STejun Heo lockdep_assert_held(&wq_mayday_lock); 2018e22bee78STejun Heo 2019493008a8STejun Heo if (!wq->rescuer) 2020493a1724STejun Heo return; 2021e22bee78STejun Heo 2022e22bee78STejun Heo /* mayday mayday mayday */ 2023493a1724STejun Heo if (list_empty(&pwq->mayday_node)) { 202477668c8bSLai Jiangshan /* 202577668c8bSLai Jiangshan * If @pwq is for an unbound wq, its base ref may be put at 202677668c8bSLai Jiangshan * any time due to an attribute change. Pin @pwq until the 202777668c8bSLai Jiangshan * rescuer is done with it. 202877668c8bSLai Jiangshan */ 202977668c8bSLai Jiangshan get_pwq(pwq); 2030493a1724STejun Heo list_add_tail(&pwq->mayday_node, &wq->maydays); 2031e22bee78STejun Heo wake_up_process(wq->rescuer->task); 2032493a1724STejun Heo } 2033e22bee78STejun Heo } 2034e22bee78STejun Heo 203532a6c723SKees Cook static void pool_mayday_timeout(struct timer_list *t) 2036e22bee78STejun Heo { 203732a6c723SKees Cook struct worker_pool *pool = from_timer(pool, t, mayday_timer); 2038e22bee78STejun Heo struct work_struct *work; 2039e22bee78STejun Heo 2040b2d82909STejun Heo spin_lock_irq(&pool->lock); 2041b2d82909STejun Heo spin_lock(&wq_mayday_lock); /* for wq->maydays */ 2042e22bee78STejun Heo 204363d95a91STejun Heo if (need_to_create_worker(pool)) { 2044e22bee78STejun Heo /* 2045e22bee78STejun Heo * We've been trying to create a new worker but 2046e22bee78STejun Heo * haven't been successful. We might be hitting an 2047e22bee78STejun Heo * allocation deadlock. Send distress signals to 2048e22bee78STejun Heo * rescuers. 2049e22bee78STejun Heo */ 205063d95a91STejun Heo list_for_each_entry(work, &pool->worklist, entry) 2051e22bee78STejun Heo send_mayday(work); 2052e22bee78STejun Heo } 2053e22bee78STejun Heo 2054b2d82909STejun Heo spin_unlock(&wq_mayday_lock); 2055b2d82909STejun Heo spin_unlock_irq(&pool->lock); 2056e22bee78STejun Heo 205763d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 2058e22bee78STejun Heo } 2059e22bee78STejun Heo 2060e22bee78STejun Heo /** 2061e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 206263d95a91STejun Heo * @pool: pool to create a new worker for 2063e22bee78STejun Heo * 206463d95a91STejun Heo * Create a new worker for @pool if necessary. @pool is guaranteed to 2065e22bee78STejun Heo * have at least one idle worker on return from this function. If 2066e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 206763d95a91STejun Heo * sent to all rescuers with works scheduled on @pool to resolve 2068e22bee78STejun Heo * possible allocation deadlock. 2069e22bee78STejun Heo * 2070c5aa87bbSTejun Heo * On return, need_to_create_worker() is guaranteed to be %false and 2071c5aa87bbSTejun Heo * may_start_working() %true. 2072e22bee78STejun Heo * 2073e22bee78STejun Heo * LOCKING: 2074d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2075e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 2076e22bee78STejun Heo * manager. 2077e22bee78STejun Heo */ 207829187a9eSTejun Heo static void maybe_create_worker(struct worker_pool *pool) 2079d565ed63STejun Heo __releases(&pool->lock) 2080d565ed63STejun Heo __acquires(&pool->lock) 2081e22bee78STejun Heo { 2082e22bee78STejun Heo restart: 2083d565ed63STejun Heo spin_unlock_irq(&pool->lock); 20849f9c2364STejun Heo 2085e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 208663d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 2087e22bee78STejun Heo 2088e22bee78STejun Heo while (true) { 2089051e1850SLai Jiangshan if (create_worker(pool) || !need_to_create_worker(pool)) 2090e22bee78STejun Heo break; 2091e22bee78STejun Heo 2092e212f361SLai Jiangshan schedule_timeout_interruptible(CREATE_COOLDOWN); 20939f9c2364STejun Heo 209463d95a91STejun Heo if (!need_to_create_worker(pool)) 2095e22bee78STejun Heo break; 2096e22bee78STejun Heo } 2097e22bee78STejun Heo 209863d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 2099d565ed63STejun Heo spin_lock_irq(&pool->lock); 2100051e1850SLai Jiangshan /* 2101051e1850SLai Jiangshan * This is necessary even after a new worker was just successfully 2102051e1850SLai Jiangshan * created as @pool->lock was dropped and the new worker might have 2103051e1850SLai Jiangshan * already become busy. 2104051e1850SLai Jiangshan */ 210563d95a91STejun Heo if (need_to_create_worker(pool)) 2106e22bee78STejun Heo goto restart; 2107e22bee78STejun Heo } 2108e22bee78STejun Heo 2109e22bee78STejun Heo /** 2110e22bee78STejun Heo * manage_workers - manage worker pool 2111e22bee78STejun Heo * @worker: self 2112e22bee78STejun Heo * 2113706026c2STejun Heo * Assume the manager role and manage the worker pool @worker belongs 2114e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 2115706026c2STejun Heo * pool. The exclusion is handled automatically by this function. 2116e22bee78STejun Heo * 2117e22bee78STejun Heo * The caller can safely start processing works on false return. On 2118e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 2119e22bee78STejun Heo * and may_start_working() is true. 2120e22bee78STejun Heo * 2121e22bee78STejun Heo * CONTEXT: 2122d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2123e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 2124e22bee78STejun Heo * 2125d185af30SYacine Belkadi * Return: 212629187a9eSTejun Heo * %false if the pool doesn't need management and the caller can safely 212729187a9eSTejun Heo * start processing works, %true if management function was performed and 212829187a9eSTejun Heo * the conditions that the caller verified before calling the function may 212929187a9eSTejun Heo * no longer be true. 2130e22bee78STejun Heo */ 2131e22bee78STejun Heo static bool manage_workers(struct worker *worker) 2132e22bee78STejun Heo { 213363d95a91STejun Heo struct worker_pool *pool = worker->pool; 2134e22bee78STejun Heo 2135692b4825STejun Heo if (pool->flags & POOL_MANAGER_ACTIVE) 213629187a9eSTejun Heo return false; 2137692b4825STejun Heo 2138692b4825STejun Heo pool->flags |= POOL_MANAGER_ACTIVE; 21392607d7a6STejun Heo pool->manager = worker; 2140e22bee78STejun Heo 214129187a9eSTejun Heo maybe_create_worker(pool); 2142e22bee78STejun Heo 21432607d7a6STejun Heo pool->manager = NULL; 2144692b4825STejun Heo pool->flags &= ~POOL_MANAGER_ACTIVE; 2145692b4825STejun Heo wake_up(&wq_manager_wait); 214629187a9eSTejun Heo return true; 2147e22bee78STejun Heo } 2148e22bee78STejun Heo 2149a62428c0STejun Heo /** 2150a62428c0STejun Heo * process_one_work - process single work 2151c34056a3STejun Heo * @worker: self 2152a62428c0STejun Heo * @work: work to process 2153a62428c0STejun Heo * 2154a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 2155a62428c0STejun Heo * process a single work including synchronization against and 2156a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 2157a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 2158a62428c0STejun Heo * call this function to process a work. 2159a62428c0STejun Heo * 2160a62428c0STejun Heo * CONTEXT: 2161d565ed63STejun Heo * spin_lock_irq(pool->lock) which is released and regrabbed. 2162a62428c0STejun Heo */ 2163c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 2164d565ed63STejun Heo __releases(&pool->lock) 2165d565ed63STejun Heo __acquires(&pool->lock) 21661da177e4SLinus Torvalds { 2167112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2168bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2169112202d9STejun Heo bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; 217073f53c4aSTejun Heo int work_color; 21717e11629dSTejun Heo struct worker *collision; 21724e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 21734e6045f1SJohannes Berg /* 2174a62428c0STejun Heo * It is permissible to free the struct work_struct from 2175a62428c0STejun Heo * inside the function that is called from it, this we need to 2176a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 2177a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 2178a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 21794e6045f1SJohannes Berg */ 21804d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 21814d82a1deSPeter Zijlstra 21824d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 21834e6045f1SJohannes Berg #endif 2184807407c0SLai Jiangshan /* ensure we're on the correct CPU */ 218585327af6SLai Jiangshan WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 2186ec22ca5eSTejun Heo raw_smp_processor_id() != pool->cpu); 218725511a47STejun Heo 21887e11629dSTejun Heo /* 21897e11629dSTejun Heo * A single work shouldn't be executed concurrently by 21907e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 21917e11629dSTejun Heo * already processing the work. If so, defer the work to the 21927e11629dSTejun Heo * currently executing one. 21937e11629dSTejun Heo */ 2194c9e7cf27STejun Heo collision = find_worker_executing_work(pool, work); 21957e11629dSTejun Heo if (unlikely(collision)) { 21967e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 21977e11629dSTejun Heo return; 21987e11629dSTejun Heo } 21991da177e4SLinus Torvalds 22008930cabaSTejun Heo /* claim and dequeue */ 22011da177e4SLinus Torvalds debug_work_deactivate(work); 2202c9e7cf27STejun Heo hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); 2203c34056a3STejun Heo worker->current_work = work; 2204a2c1c57bSTejun Heo worker->current_func = work->func; 2205112202d9STejun Heo worker->current_pwq = pwq; 220673f53c4aSTejun Heo work_color = get_work_color(work); 22077a22ad75STejun Heo 22088bf89593STejun Heo /* 22098bf89593STejun Heo * Record wq name for cmdline and debug reporting, may get 22108bf89593STejun Heo * overridden through set_worker_desc(). 22118bf89593STejun Heo */ 22128bf89593STejun Heo strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN); 22138bf89593STejun Heo 2214a62428c0STejun Heo list_del_init(&work->entry); 2215a62428c0STejun Heo 2216649027d7STejun Heo /* 2217228f1d00SLai Jiangshan * CPU intensive works don't participate in concurrency management. 2218228f1d00SLai Jiangshan * They're the scheduler's responsibility. This takes @worker out 2219228f1d00SLai Jiangshan * of concurrency management and the next code block will chain 2220228f1d00SLai Jiangshan * execution of the pending work items. 2221fb0e7bebSTejun Heo */ 2222fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2223228f1d00SLai Jiangshan worker_set_flags(worker, WORKER_CPU_INTENSIVE); 2224fb0e7bebSTejun Heo 2225974271c4STejun Heo /* 2226a489a03eSLai Jiangshan * Wake up another worker if necessary. The condition is always 2227a489a03eSLai Jiangshan * false for normal per-cpu workers since nr_running would always 2228a489a03eSLai Jiangshan * be >= 1 at this point. This is used to chain execution of the 2229a489a03eSLai Jiangshan * pending work items for WORKER_NOT_RUNNING workers such as the 2230228f1d00SLai Jiangshan * UNBOUND and CPU_INTENSIVE ones. 2231974271c4STejun Heo */ 2232a489a03eSLai Jiangshan if (need_more_worker(pool)) 223363d95a91STejun Heo wake_up_worker(pool); 2234974271c4STejun Heo 22358930cabaSTejun Heo /* 22367c3eed5cSTejun Heo * Record the last pool and clear PENDING which should be the last 2237d565ed63STejun Heo * update to @work. Also, do this inside @pool->lock so that 223823657bb1STejun Heo * PENDING and queued state changes happen together while IRQ is 223923657bb1STejun Heo * disabled. 22408930cabaSTejun Heo */ 22417c3eed5cSTejun Heo set_work_pool_and_clear_pending(work, pool->id); 22421da177e4SLinus Torvalds 2243d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2244365970a1SDavid Howells 2245a1d14934SPeter Zijlstra lock_map_acquire(&pwq->wq->lockdep_map); 22463295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 2247e6f3faa7SPeter Zijlstra /* 2248f52be570SPeter Zijlstra * Strictly speaking we should mark the invariant state without holding 2249f52be570SPeter Zijlstra * any locks, that is, before these two lock_map_acquire()'s. 2250e6f3faa7SPeter Zijlstra * 2251e6f3faa7SPeter Zijlstra * However, that would result in: 2252e6f3faa7SPeter Zijlstra * 2253e6f3faa7SPeter Zijlstra * A(W1) 2254e6f3faa7SPeter Zijlstra * WFC(C) 2255e6f3faa7SPeter Zijlstra * A(W1) 2256e6f3faa7SPeter Zijlstra * C(C) 2257e6f3faa7SPeter Zijlstra * 2258e6f3faa7SPeter Zijlstra * Which would create W1->C->W1 dependencies, even though there is no 2259e6f3faa7SPeter Zijlstra * actual deadlock possible. There are two solutions, using a 2260e6f3faa7SPeter Zijlstra * read-recursive acquire on the work(queue) 'locks', but this will then 2261f52be570SPeter Zijlstra * hit the lockdep limitation on recursive locks, or simply discard 2262e6f3faa7SPeter Zijlstra * these locks. 2263e6f3faa7SPeter Zijlstra * 2264e6f3faa7SPeter Zijlstra * AFAICT there is no possible deadlock scenario between the 2265e6f3faa7SPeter Zijlstra * flush_work() and complete() primitives (except for single-threaded 2266e6f3faa7SPeter Zijlstra * workqueues), so hiding them isn't a problem. 2267e6f3faa7SPeter Zijlstra */ 2268f52be570SPeter Zijlstra lockdep_invariant_state(true); 2269e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 2270a2c1c57bSTejun Heo worker->current_func(work); 2271e36c886aSArjan van de Ven /* 2272e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 2273e36c886aSArjan van de Ven * point will only record its address. 2274e36c886aSArjan van de Ven */ 2275e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 22763295f0efSIngo Molnar lock_map_release(&lockdep_map); 2277112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 22781da177e4SLinus Torvalds 2279d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 2280044c782cSValentin Ilie pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" 2281d75f773cSSakari Ailus " last function: %ps\n", 2282a2c1c57bSTejun Heo current->comm, preempt_count(), task_pid_nr(current), 2283a2c1c57bSTejun Heo worker->current_func); 2284d5abe669SPeter Zijlstra debug_show_held_locks(current); 2285d5abe669SPeter Zijlstra dump_stack(); 2286d5abe669SPeter Zijlstra } 2287d5abe669SPeter Zijlstra 2288b22ce278STejun Heo /* 2289b22ce278STejun Heo * The following prevents a kworker from hogging CPU on !PREEMPT 2290b22ce278STejun Heo * kernels, where a requeueing work item waiting for something to 2291b22ce278STejun Heo * happen could deadlock with stop_machine as such work item could 2292b22ce278STejun Heo * indefinitely requeue itself while all other CPUs are trapped in 2293789cbbecSJoe Lawrence * stop_machine. At the same time, report a quiescent RCU state so 2294789cbbecSJoe Lawrence * the same condition doesn't freeze RCU. 2295b22ce278STejun Heo */ 2296a7e6425eSPaul E. McKenney cond_resched(); 2297b22ce278STejun Heo 2298d565ed63STejun Heo spin_lock_irq(&pool->lock); 2299a62428c0STejun Heo 2300fb0e7bebSTejun Heo /* clear cpu intensive status */ 2301fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2302fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 2303fb0e7bebSTejun Heo 23041b69ac6bSJohannes Weiner /* tag the worker for identification in schedule() */ 23051b69ac6bSJohannes Weiner worker->last_func = worker->current_func; 23061b69ac6bSJohannes Weiner 2307a62428c0STejun Heo /* we're done with it, release */ 230842f8570fSSasha Levin hash_del(&worker->hentry); 2309c34056a3STejun Heo worker->current_work = NULL; 2310a2c1c57bSTejun Heo worker->current_func = NULL; 2311112202d9STejun Heo worker->current_pwq = NULL; 2312112202d9STejun Heo pwq_dec_nr_in_flight(pwq, work_color); 23131da177e4SLinus Torvalds } 23141da177e4SLinus Torvalds 2315affee4b2STejun Heo /** 2316affee4b2STejun Heo * process_scheduled_works - process scheduled works 2317affee4b2STejun Heo * @worker: self 2318affee4b2STejun Heo * 2319affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 2320affee4b2STejun Heo * may change while processing a work, so this function repeatedly 2321affee4b2STejun Heo * fetches a work from the top and executes it. 2322affee4b2STejun Heo * 2323affee4b2STejun Heo * CONTEXT: 2324d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2325affee4b2STejun Heo * multiple times. 2326affee4b2STejun Heo */ 2327affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 23281da177e4SLinus Torvalds { 2329affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 2330affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 2331a62428c0STejun Heo struct work_struct, entry); 2332c34056a3STejun Heo process_one_work(worker, work); 2333a62428c0STejun Heo } 23341da177e4SLinus Torvalds } 23351da177e4SLinus Torvalds 2336197f6accSTejun Heo static void set_pf_worker(bool val) 2337197f6accSTejun Heo { 2338197f6accSTejun Heo mutex_lock(&wq_pool_attach_mutex); 2339197f6accSTejun Heo if (val) 2340197f6accSTejun Heo current->flags |= PF_WQ_WORKER; 2341197f6accSTejun Heo else 2342197f6accSTejun Heo current->flags &= ~PF_WQ_WORKER; 2343197f6accSTejun Heo mutex_unlock(&wq_pool_attach_mutex); 2344197f6accSTejun Heo } 2345197f6accSTejun Heo 23464690c4abSTejun Heo /** 23474690c4abSTejun Heo * worker_thread - the worker thread function 2348c34056a3STejun Heo * @__worker: self 23494690c4abSTejun Heo * 2350c5aa87bbSTejun Heo * The worker thread function. All workers belong to a worker_pool - 2351c5aa87bbSTejun Heo * either a per-cpu one or dynamic unbound one. These workers process all 2352c5aa87bbSTejun Heo * work items regardless of their specific target workqueue. The only 2353c5aa87bbSTejun Heo * exception is work items which belong to workqueues with a rescuer which 2354c5aa87bbSTejun Heo * will be explained in rescuer_thread(). 2355d185af30SYacine Belkadi * 2356d185af30SYacine Belkadi * Return: 0 23574690c4abSTejun Heo */ 2358c34056a3STejun Heo static int worker_thread(void *__worker) 23591da177e4SLinus Torvalds { 2360c34056a3STejun Heo struct worker *worker = __worker; 2361bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 23621da177e4SLinus Torvalds 2363e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 2364197f6accSTejun Heo set_pf_worker(true); 2365c8e55f36STejun Heo woke_up: 2366d565ed63STejun Heo spin_lock_irq(&pool->lock); 2367affee4b2STejun Heo 2368a9ab775bSTejun Heo /* am I supposed to die? */ 2369a9ab775bSTejun Heo if (unlikely(worker->flags & WORKER_DIE)) { 2370d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2371a9ab775bSTejun Heo WARN_ON_ONCE(!list_empty(&worker->entry)); 2372197f6accSTejun Heo set_pf_worker(false); 237360f5a4bcSLai Jiangshan 237460f5a4bcSLai Jiangshan set_task_comm(worker->task, "kworker/dying"); 23757cda9aaeSLai Jiangshan ida_simple_remove(&pool->worker_ida, worker->id); 2376a2d812a2STejun Heo worker_detach_from_pool(worker); 237760f5a4bcSLai Jiangshan kfree(worker); 2378c8e55f36STejun Heo return 0; 2379c8e55f36STejun Heo } 2380c8e55f36STejun Heo 2381c8e55f36STejun Heo worker_leave_idle(worker); 2382db7bccf4STejun Heo recheck: 2383e22bee78STejun Heo /* no more worker necessary? */ 238463d95a91STejun Heo if (!need_more_worker(pool)) 2385e22bee78STejun Heo goto sleep; 2386e22bee78STejun Heo 2387e22bee78STejun Heo /* do we need to manage? */ 238863d95a91STejun Heo if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 2389e22bee78STejun Heo goto recheck; 2390e22bee78STejun Heo 2391c8e55f36STejun Heo /* 2392c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 2393c8e55f36STejun Heo * preparing to process a work or actually processing it. 2394c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 2395c8e55f36STejun Heo */ 23966183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->scheduled)); 2397c8e55f36STejun Heo 2398e22bee78STejun Heo /* 2399a9ab775bSTejun Heo * Finish PREP stage. We're guaranteed to have at least one idle 2400a9ab775bSTejun Heo * worker or that someone else has already assumed the manager 2401a9ab775bSTejun Heo * role. This is where @worker starts participating in concurrency 2402a9ab775bSTejun Heo * management if applicable and concurrency management is restored 2403a9ab775bSTejun Heo * after being rebound. See rebind_workers() for details. 2404e22bee78STejun Heo */ 2405a9ab775bSTejun Heo worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); 2406e22bee78STejun Heo 2407e22bee78STejun Heo do { 2408affee4b2STejun Heo struct work_struct *work = 2409bd7bdd43STejun Heo list_first_entry(&pool->worklist, 2410affee4b2STejun Heo struct work_struct, entry); 2411affee4b2STejun Heo 241282607adcSTejun Heo pool->watchdog_ts = jiffies; 241382607adcSTejun Heo 2414c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 2415affee4b2STejun Heo /* optimization path, not strictly necessary */ 2416affee4b2STejun Heo process_one_work(worker, work); 2417affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 2418affee4b2STejun Heo process_scheduled_works(worker); 2419affee4b2STejun Heo } else { 2420c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 2421affee4b2STejun Heo process_scheduled_works(worker); 2422affee4b2STejun Heo } 242363d95a91STejun Heo } while (keep_working(pool)); 2424affee4b2STejun Heo 2425228f1d00SLai Jiangshan worker_set_flags(worker, WORKER_PREP); 2426d313dd85STejun Heo sleep: 2427c8e55f36STejun Heo /* 2428d565ed63STejun Heo * pool->lock is held and there's no work to process and no need to 2429d565ed63STejun Heo * manage, sleep. Workers are woken up only while holding 2430d565ed63STejun Heo * pool->lock or from local cpu, so setting the current state 2431d565ed63STejun Heo * before releasing pool->lock is enough to prevent losing any 2432d565ed63STejun Heo * event. 2433c8e55f36STejun Heo */ 2434c8e55f36STejun Heo worker_enter_idle(worker); 2435c5a94a61SPeter Zijlstra __set_current_state(TASK_IDLE); 2436d565ed63STejun Heo spin_unlock_irq(&pool->lock); 24371da177e4SLinus Torvalds schedule(); 2438c8e55f36STejun Heo goto woke_up; 24391da177e4SLinus Torvalds } 24401da177e4SLinus Torvalds 2441e22bee78STejun Heo /** 2442e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2443111c225aSTejun Heo * @__rescuer: self 2444e22bee78STejun Heo * 2445e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2446493008a8STejun Heo * workqueue which has WQ_MEM_RECLAIM set. 2447e22bee78STejun Heo * 2448706026c2STejun Heo * Regular work processing on a pool may block trying to create a new 2449e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2450e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2451e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2452e22bee78STejun Heo * the problem rescuer solves. 2453e22bee78STejun Heo * 2454706026c2STejun Heo * When such condition is possible, the pool summons rescuers of all 2455706026c2STejun Heo * workqueues which have works queued on the pool and let them process 2456e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2457e22bee78STejun Heo * 2458e22bee78STejun Heo * This should happen rarely. 2459d185af30SYacine Belkadi * 2460d185af30SYacine Belkadi * Return: 0 2461e22bee78STejun Heo */ 2462111c225aSTejun Heo static int rescuer_thread(void *__rescuer) 2463e22bee78STejun Heo { 2464111c225aSTejun Heo struct worker *rescuer = __rescuer; 2465111c225aSTejun Heo struct workqueue_struct *wq = rescuer->rescue_wq; 2466e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 24674d595b86SLai Jiangshan bool should_stop; 2468e22bee78STejun Heo 2469e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2470111c225aSTejun Heo 2471111c225aSTejun Heo /* 2472111c225aSTejun Heo * Mark rescuer as worker too. As WORKER_PREP is never cleared, it 2473111c225aSTejun Heo * doesn't participate in concurrency management. 2474111c225aSTejun Heo */ 2475197f6accSTejun Heo set_pf_worker(true); 2476e22bee78STejun Heo repeat: 2477c5a94a61SPeter Zijlstra set_current_state(TASK_IDLE); 24781da177e4SLinus Torvalds 24794d595b86SLai Jiangshan /* 24804d595b86SLai Jiangshan * By the time the rescuer is requested to stop, the workqueue 24814d595b86SLai Jiangshan * shouldn't have any work pending, but @wq->maydays may still have 24824d595b86SLai Jiangshan * pwq(s) queued. This can happen by non-rescuer workers consuming 24834d595b86SLai Jiangshan * all the work items before the rescuer got to them. Go through 24844d595b86SLai Jiangshan * @wq->maydays processing before acting on should_stop so that the 24854d595b86SLai Jiangshan * list is always empty on exit. 24864d595b86SLai Jiangshan */ 24874d595b86SLai Jiangshan should_stop = kthread_should_stop(); 24881da177e4SLinus Torvalds 2489493a1724STejun Heo /* see whether any pwq is asking for help */ 24902e109a28STejun Heo spin_lock_irq(&wq_mayday_lock); 2491493a1724STejun Heo 2492493a1724STejun Heo while (!list_empty(&wq->maydays)) { 2493493a1724STejun Heo struct pool_workqueue *pwq = list_first_entry(&wq->maydays, 2494493a1724STejun Heo struct pool_workqueue, mayday_node); 2495112202d9STejun Heo struct worker_pool *pool = pwq->pool; 2496e22bee78STejun Heo struct work_struct *work, *n; 249782607adcSTejun Heo bool first = true; 2498e22bee78STejun Heo 2499e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2500493a1724STejun Heo list_del_init(&pwq->mayday_node); 2501493a1724STejun Heo 25022e109a28STejun Heo spin_unlock_irq(&wq_mayday_lock); 2503e22bee78STejun Heo 250451697d39SLai Jiangshan worker_attach_to_pool(rescuer, pool); 250551697d39SLai Jiangshan 250651697d39SLai Jiangshan spin_lock_irq(&pool->lock); 2507e22bee78STejun Heo 2508e22bee78STejun Heo /* 2509e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2510e22bee78STejun Heo * process'em. 2511e22bee78STejun Heo */ 25120479c8c5STejun Heo WARN_ON_ONCE(!list_empty(scheduled)); 251382607adcSTejun Heo list_for_each_entry_safe(work, n, &pool->worklist, entry) { 251482607adcSTejun Heo if (get_work_pwq(work) == pwq) { 251582607adcSTejun Heo if (first) 251682607adcSTejun Heo pool->watchdog_ts = jiffies; 2517e22bee78STejun Heo move_linked_works(work, scheduled, &n); 251882607adcSTejun Heo } 251982607adcSTejun Heo first = false; 252082607adcSTejun Heo } 2521e22bee78STejun Heo 2522008847f6SNeilBrown if (!list_empty(scheduled)) { 2523e22bee78STejun Heo process_scheduled_works(rescuer); 25247576958aSTejun Heo 25257576958aSTejun Heo /* 2526008847f6SNeilBrown * The above execution of rescued work items could 2527008847f6SNeilBrown * have created more to rescue through 2528008847f6SNeilBrown * pwq_activate_first_delayed() or chained 2529008847f6SNeilBrown * queueing. Let's put @pwq back on mayday list so 2530008847f6SNeilBrown * that such back-to-back work items, which may be 2531008847f6SNeilBrown * being used to relieve memory pressure, don't 2532008847f6SNeilBrown * incur MAYDAY_INTERVAL delay inbetween. 2533008847f6SNeilBrown */ 2534008847f6SNeilBrown if (need_to_create_worker(pool)) { 2535008847f6SNeilBrown spin_lock(&wq_mayday_lock); 2536008847f6SNeilBrown get_pwq(pwq); 2537008847f6SNeilBrown list_move_tail(&pwq->mayday_node, &wq->maydays); 2538008847f6SNeilBrown spin_unlock(&wq_mayday_lock); 2539008847f6SNeilBrown } 2540008847f6SNeilBrown } 2541008847f6SNeilBrown 2542008847f6SNeilBrown /* 254377668c8bSLai Jiangshan * Put the reference grabbed by send_mayday(). @pool won't 254413b1d625SLai Jiangshan * go away while we're still attached to it. 254577668c8bSLai Jiangshan */ 254677668c8bSLai Jiangshan put_pwq(pwq); 254777668c8bSLai Jiangshan 254877668c8bSLai Jiangshan /* 2549d8ca83e6SLai Jiangshan * Leave this pool. If need_more_worker() is %true, notify a 25507576958aSTejun Heo * regular worker; otherwise, we end up with 0 concurrency 25517576958aSTejun Heo * and stalling the execution. 25527576958aSTejun Heo */ 2553d8ca83e6SLai Jiangshan if (need_more_worker(pool)) 255463d95a91STejun Heo wake_up_worker(pool); 25557576958aSTejun Heo 255613b1d625SLai Jiangshan spin_unlock_irq(&pool->lock); 255713b1d625SLai Jiangshan 2558a2d812a2STejun Heo worker_detach_from_pool(rescuer); 255913b1d625SLai Jiangshan 256013b1d625SLai Jiangshan spin_lock_irq(&wq_mayday_lock); 25611da177e4SLinus Torvalds } 25621da177e4SLinus Torvalds 25632e109a28STejun Heo spin_unlock_irq(&wq_mayday_lock); 2564493a1724STejun Heo 25654d595b86SLai Jiangshan if (should_stop) { 25664d595b86SLai Jiangshan __set_current_state(TASK_RUNNING); 2567197f6accSTejun Heo set_pf_worker(false); 25684d595b86SLai Jiangshan return 0; 25694d595b86SLai Jiangshan } 25704d595b86SLai Jiangshan 2571111c225aSTejun Heo /* rescuers should never participate in concurrency management */ 2572111c225aSTejun Heo WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); 2573e22bee78STejun Heo schedule(); 2574e22bee78STejun Heo goto repeat; 25751da177e4SLinus Torvalds } 25761da177e4SLinus Torvalds 2577fca839c0STejun Heo /** 2578fca839c0STejun Heo * check_flush_dependency - check for flush dependency sanity 2579fca839c0STejun Heo * @target_wq: workqueue being flushed 2580fca839c0STejun Heo * @target_work: work item being flushed (NULL for workqueue flushes) 2581fca839c0STejun Heo * 2582fca839c0STejun Heo * %current is trying to flush the whole @target_wq or @target_work on it. 2583fca839c0STejun Heo * If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not 2584fca839c0STejun Heo * reclaiming memory or running on a workqueue which doesn't have 2585fca839c0STejun Heo * %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to 2586fca839c0STejun Heo * a deadlock. 2587fca839c0STejun Heo */ 2588fca839c0STejun Heo static void check_flush_dependency(struct workqueue_struct *target_wq, 2589fca839c0STejun Heo struct work_struct *target_work) 2590fca839c0STejun Heo { 2591fca839c0STejun Heo work_func_t target_func = target_work ? target_work->func : NULL; 2592fca839c0STejun Heo struct worker *worker; 2593fca839c0STejun Heo 2594fca839c0STejun Heo if (target_wq->flags & WQ_MEM_RECLAIM) 2595fca839c0STejun Heo return; 2596fca839c0STejun Heo 2597fca839c0STejun Heo worker = current_wq_worker(); 2598fca839c0STejun Heo 2599fca839c0STejun Heo WARN_ONCE(current->flags & PF_MEMALLOC, 2600d75f773cSSakari Ailus "workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps", 2601fca839c0STejun Heo current->pid, current->comm, target_wq->name, target_func); 260223d11a58STejun Heo WARN_ONCE(worker && ((worker->current_pwq->wq->flags & 260323d11a58STejun Heo (WQ_MEM_RECLAIM | __WQ_LEGACY)) == WQ_MEM_RECLAIM), 2604d75f773cSSakari Ailus "workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps", 2605fca839c0STejun Heo worker->current_pwq->wq->name, worker->current_func, 2606fca839c0STejun Heo target_wq->name, target_func); 2607fca839c0STejun Heo } 2608fca839c0STejun Heo 2609fc2e4d70SOleg Nesterov struct wq_barrier { 2610fc2e4d70SOleg Nesterov struct work_struct work; 2611fc2e4d70SOleg Nesterov struct completion done; 26122607d7a6STejun Heo struct task_struct *task; /* purely informational */ 2613fc2e4d70SOleg Nesterov }; 2614fc2e4d70SOleg Nesterov 2615fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2616fc2e4d70SOleg Nesterov { 2617fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2618fc2e4d70SOleg Nesterov complete(&barr->done); 2619fc2e4d70SOleg Nesterov } 2620fc2e4d70SOleg Nesterov 26214690c4abSTejun Heo /** 26224690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 2623112202d9STejun Heo * @pwq: pwq to insert barrier into 26244690c4abSTejun Heo * @barr: wq_barrier to insert 2625affee4b2STejun Heo * @target: target work to attach @barr to 2626affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 26274690c4abSTejun Heo * 2628affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2629affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2630affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2631affee4b2STejun Heo * cpu. 2632affee4b2STejun Heo * 2633affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2634affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2635affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2636affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2637affee4b2STejun Heo * after a work with LINKED flag set. 2638affee4b2STejun Heo * 2639affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2640112202d9STejun Heo * underneath us, so we can't reliably determine pwq from @target. 26414690c4abSTejun Heo * 26424690c4abSTejun Heo * CONTEXT: 2643d565ed63STejun Heo * spin_lock_irq(pool->lock). 26444690c4abSTejun Heo */ 2645112202d9STejun Heo static void insert_wq_barrier(struct pool_workqueue *pwq, 2646affee4b2STejun Heo struct wq_barrier *barr, 2647affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2648fc2e4d70SOleg Nesterov { 2649affee4b2STejun Heo struct list_head *head; 2650affee4b2STejun Heo unsigned int linked = 0; 2651affee4b2STejun Heo 2652dc186ad7SThomas Gleixner /* 2653d565ed63STejun Heo * debugobject calls are safe here even with pool->lock locked 2654dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2655dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2656dc186ad7SThomas Gleixner * might deadlock. 2657dc186ad7SThomas Gleixner */ 2658ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 265922df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 266052fa5bc5SBoqun Feng 2661fd1a5b04SByungchul Park init_completion_map(&barr->done, &target->lockdep_map); 2662fd1a5b04SByungchul Park 26632607d7a6STejun Heo barr->task = current; 266483c22520SOleg Nesterov 2665affee4b2STejun Heo /* 2666affee4b2STejun Heo * If @target is currently being executed, schedule the 2667affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2668affee4b2STejun Heo */ 2669affee4b2STejun Heo if (worker) 2670affee4b2STejun Heo head = worker->scheduled.next; 2671affee4b2STejun Heo else { 2672affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2673affee4b2STejun Heo 2674affee4b2STejun Heo head = target->entry.next; 2675affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2676affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2677affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2678affee4b2STejun Heo } 2679affee4b2STejun Heo 2680dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2681112202d9STejun Heo insert_work(pwq, &barr->work, head, 2682affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2683fc2e4d70SOleg Nesterov } 2684fc2e4d70SOleg Nesterov 268573f53c4aSTejun Heo /** 2686112202d9STejun Heo * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing 268773f53c4aSTejun Heo * @wq: workqueue being flushed 268873f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 268973f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 269073f53c4aSTejun Heo * 2691112202d9STejun Heo * Prepare pwqs for workqueue flushing. 269273f53c4aSTejun Heo * 2693112202d9STejun Heo * If @flush_color is non-negative, flush_color on all pwqs should be 2694112202d9STejun Heo * -1. If no pwq has in-flight commands at the specified color, all 2695112202d9STejun Heo * pwq->flush_color's stay at -1 and %false is returned. If any pwq 2696112202d9STejun Heo * has in flight commands, its pwq->flush_color is set to 2697112202d9STejun Heo * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq 269873f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 269973f53c4aSTejun Heo * 270073f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 270173f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 270273f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 270373f53c4aSTejun Heo * is returned. 270473f53c4aSTejun Heo * 2705112202d9STejun Heo * If @work_color is non-negative, all pwqs should have the same 270673f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 270773f53c4aSTejun Heo * advanced to @work_color. 270873f53c4aSTejun Heo * 270973f53c4aSTejun Heo * CONTEXT: 27103c25a55dSLai Jiangshan * mutex_lock(wq->mutex). 271173f53c4aSTejun Heo * 2712d185af30SYacine Belkadi * Return: 271373f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 271473f53c4aSTejun Heo * otherwise. 271573f53c4aSTejun Heo */ 2716112202d9STejun Heo static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, 271773f53c4aSTejun Heo int flush_color, int work_color) 27181da177e4SLinus Torvalds { 271973f53c4aSTejun Heo bool wait = false; 272049e3cf44STejun Heo struct pool_workqueue *pwq; 27211da177e4SLinus Torvalds 272273f53c4aSTejun Heo if (flush_color >= 0) { 27236183c009STejun Heo WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); 2724112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 1); 2725dc186ad7SThomas Gleixner } 272614441960SOleg Nesterov 272749e3cf44STejun Heo for_each_pwq(pwq, wq) { 2728112202d9STejun Heo struct worker_pool *pool = pwq->pool; 27291da177e4SLinus Torvalds 2730b09f4fd3SLai Jiangshan spin_lock_irq(&pool->lock); 273173f53c4aSTejun Heo 273273f53c4aSTejun Heo if (flush_color >= 0) { 27336183c009STejun Heo WARN_ON_ONCE(pwq->flush_color != -1); 273473f53c4aSTejun Heo 2735112202d9STejun Heo if (pwq->nr_in_flight[flush_color]) { 2736112202d9STejun Heo pwq->flush_color = flush_color; 2737112202d9STejun Heo atomic_inc(&wq->nr_pwqs_to_flush); 273873f53c4aSTejun Heo wait = true; 27391da177e4SLinus Torvalds } 274073f53c4aSTejun Heo } 274173f53c4aSTejun Heo 274273f53c4aSTejun Heo if (work_color >= 0) { 27436183c009STejun Heo WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); 2744112202d9STejun Heo pwq->work_color = work_color; 274573f53c4aSTejun Heo } 274673f53c4aSTejun Heo 2747b09f4fd3SLai Jiangshan spin_unlock_irq(&pool->lock); 27481da177e4SLinus Torvalds } 27491da177e4SLinus Torvalds 2750112202d9STejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) 275173f53c4aSTejun Heo complete(&wq->first_flusher->done); 275273f53c4aSTejun Heo 275373f53c4aSTejun Heo return wait; 275483c22520SOleg Nesterov } 27551da177e4SLinus Torvalds 27560fcb78c2SRolf Eike Beer /** 27571da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 27580fcb78c2SRolf Eike Beer * @wq: workqueue to flush 27591da177e4SLinus Torvalds * 2760c5aa87bbSTejun Heo * This function sleeps until all work items which were queued on entry 2761c5aa87bbSTejun Heo * have finished execution, but it is not livelocked by new incoming ones. 27621da177e4SLinus Torvalds */ 27637ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 27641da177e4SLinus Torvalds { 276573f53c4aSTejun Heo struct wq_flusher this_flusher = { 276673f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 276773f53c4aSTejun Heo .flush_color = -1, 2768fd1a5b04SByungchul Park .done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map), 276973f53c4aSTejun Heo }; 277073f53c4aSTejun Heo int next_color; 2771b1f4ec17SOleg Nesterov 27723347fa09STejun Heo if (WARN_ON(!wq_online)) 27733347fa09STejun Heo return; 27743347fa09STejun Heo 277587915adcSJohannes Berg lock_map_acquire(&wq->lockdep_map); 277687915adcSJohannes Berg lock_map_release(&wq->lockdep_map); 277787915adcSJohannes Berg 27783c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 277973f53c4aSTejun Heo 278073f53c4aSTejun Heo /* 278173f53c4aSTejun Heo * Start-to-wait phase 278273f53c4aSTejun Heo */ 278373f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 278473f53c4aSTejun Heo 278573f53c4aSTejun Heo if (next_color != wq->flush_color) { 278673f53c4aSTejun Heo /* 278773f53c4aSTejun Heo * Color space is not full. The current work_color 278873f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 278973f53c4aSTejun Heo * by one. 279073f53c4aSTejun Heo */ 27916183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); 279273f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 279373f53c4aSTejun Heo wq->work_color = next_color; 279473f53c4aSTejun Heo 279573f53c4aSTejun Heo if (!wq->first_flusher) { 279673f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 27976183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 279873f53c4aSTejun Heo 279973f53c4aSTejun Heo wq->first_flusher = &this_flusher; 280073f53c4aSTejun Heo 2801112202d9STejun Heo if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, 280273f53c4aSTejun Heo wq->work_color)) { 280373f53c4aSTejun Heo /* nothing to flush, done */ 280473f53c4aSTejun Heo wq->flush_color = next_color; 280573f53c4aSTejun Heo wq->first_flusher = NULL; 280673f53c4aSTejun Heo goto out_unlock; 280773f53c4aSTejun Heo } 280873f53c4aSTejun Heo } else { 280973f53c4aSTejun Heo /* wait in queue */ 28106183c009STejun Heo WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); 281173f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 2812112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 281373f53c4aSTejun Heo } 281473f53c4aSTejun Heo } else { 281573f53c4aSTejun Heo /* 281673f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 281773f53c4aSTejun Heo * The next flush completion will assign us 281873f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 281973f53c4aSTejun Heo */ 282073f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 282173f53c4aSTejun Heo } 282273f53c4aSTejun Heo 2823fca839c0STejun Heo check_flush_dependency(wq, NULL); 2824fca839c0STejun Heo 28253c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 282673f53c4aSTejun Heo 282773f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 282873f53c4aSTejun Heo 282973f53c4aSTejun Heo /* 283073f53c4aSTejun Heo * Wake-up-and-cascade phase 283173f53c4aSTejun Heo * 283273f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 283373f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 283473f53c4aSTejun Heo */ 283573f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 283673f53c4aSTejun Heo return; 283773f53c4aSTejun Heo 28383c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 283973f53c4aSTejun Heo 28404ce48b37STejun Heo /* we might have raced, check again with mutex held */ 28414ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 28424ce48b37STejun Heo goto out_unlock; 28434ce48b37STejun Heo 284473f53c4aSTejun Heo wq->first_flusher = NULL; 284573f53c4aSTejun Heo 28466183c009STejun Heo WARN_ON_ONCE(!list_empty(&this_flusher.list)); 28476183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 284873f53c4aSTejun Heo 284973f53c4aSTejun Heo while (true) { 285073f53c4aSTejun Heo struct wq_flusher *next, *tmp; 285173f53c4aSTejun Heo 285273f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 285373f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 285473f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 285573f53c4aSTejun Heo break; 285673f53c4aSTejun Heo list_del_init(&next->list); 285773f53c4aSTejun Heo complete(&next->done); 285873f53c4aSTejun Heo } 285973f53c4aSTejun Heo 28606183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && 286173f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 286273f53c4aSTejun Heo 286373f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 286473f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 286573f53c4aSTejun Heo 286673f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 286773f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 286873f53c4aSTejun Heo /* 286973f53c4aSTejun Heo * Assign the same color to all overflowed 287073f53c4aSTejun Heo * flushers, advance work_color and append to 287173f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 287273f53c4aSTejun Heo * phase for these overflowed flushers. 287373f53c4aSTejun Heo */ 287473f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 287573f53c4aSTejun Heo tmp->flush_color = wq->work_color; 287673f53c4aSTejun Heo 287773f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 287873f53c4aSTejun Heo 287973f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 288073f53c4aSTejun Heo &wq->flusher_queue); 2881112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 288273f53c4aSTejun Heo } 288373f53c4aSTejun Heo 288473f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 28856183c009STejun Heo WARN_ON_ONCE(wq->flush_color != wq->work_color); 288673f53c4aSTejun Heo break; 288773f53c4aSTejun Heo } 288873f53c4aSTejun Heo 288973f53c4aSTejun Heo /* 289073f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 2891112202d9STejun Heo * the new first flusher and arm pwqs. 289273f53c4aSTejun Heo */ 28936183c009STejun Heo WARN_ON_ONCE(wq->flush_color == wq->work_color); 28946183c009STejun Heo WARN_ON_ONCE(wq->flush_color != next->flush_color); 289573f53c4aSTejun Heo 289673f53c4aSTejun Heo list_del_init(&next->list); 289773f53c4aSTejun Heo wq->first_flusher = next; 289873f53c4aSTejun Heo 2899112202d9STejun Heo if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) 290073f53c4aSTejun Heo break; 290173f53c4aSTejun Heo 290273f53c4aSTejun Heo /* 290373f53c4aSTejun Heo * Meh... this color is already done, clear first 290473f53c4aSTejun Heo * flusher and repeat cascading. 290573f53c4aSTejun Heo */ 290673f53c4aSTejun Heo wq->first_flusher = NULL; 290773f53c4aSTejun Heo } 290873f53c4aSTejun Heo 290973f53c4aSTejun Heo out_unlock: 29103c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 29111da177e4SLinus Torvalds } 29121dadafa8STim Gardner EXPORT_SYMBOL(flush_workqueue); 29131da177e4SLinus Torvalds 29149c5a2ba7STejun Heo /** 29159c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 29169c5a2ba7STejun Heo * @wq: workqueue to drain 29179c5a2ba7STejun Heo * 29189c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 29199c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 29209c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 2921b749b1b6SChen Hanxiao * repeatedly until it becomes empty. The number of flushing is determined 29229c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 29239c5a2ba7STejun Heo * takes too long. 29249c5a2ba7STejun Heo */ 29259c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 29269c5a2ba7STejun Heo { 29279c5a2ba7STejun Heo unsigned int flush_cnt = 0; 292849e3cf44STejun Heo struct pool_workqueue *pwq; 29299c5a2ba7STejun Heo 29309c5a2ba7STejun Heo /* 29319c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 29329c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 2933618b01ebSTejun Heo * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. 29349c5a2ba7STejun Heo */ 293587fc741eSLai Jiangshan mutex_lock(&wq->mutex); 29369c5a2ba7STejun Heo if (!wq->nr_drainers++) 2937618b01ebSTejun Heo wq->flags |= __WQ_DRAINING; 293887fc741eSLai Jiangshan mutex_unlock(&wq->mutex); 29399c5a2ba7STejun Heo reflush: 29409c5a2ba7STejun Heo flush_workqueue(wq); 29419c5a2ba7STejun Heo 2942b09f4fd3SLai Jiangshan mutex_lock(&wq->mutex); 294376af4d93STejun Heo 294449e3cf44STejun Heo for_each_pwq(pwq, wq) { 2945fa2563e4SThomas Tuttle bool drained; 29469c5a2ba7STejun Heo 2947b09f4fd3SLai Jiangshan spin_lock_irq(&pwq->pool->lock); 2948112202d9STejun Heo drained = !pwq->nr_active && list_empty(&pwq->delayed_works); 2949b09f4fd3SLai Jiangshan spin_unlock_irq(&pwq->pool->lock); 2950fa2563e4SThomas Tuttle 2951fa2563e4SThomas Tuttle if (drained) 29529c5a2ba7STejun Heo continue; 29539c5a2ba7STejun Heo 29549c5a2ba7STejun Heo if (++flush_cnt == 10 || 29559c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 2956c5aa87bbSTejun Heo pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n", 29579c5a2ba7STejun Heo wq->name, flush_cnt); 295876af4d93STejun Heo 2959b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 29609c5a2ba7STejun Heo goto reflush; 29619c5a2ba7STejun Heo } 29629c5a2ba7STejun Heo 29639c5a2ba7STejun Heo if (!--wq->nr_drainers) 2964618b01ebSTejun Heo wq->flags &= ~__WQ_DRAINING; 296587fc741eSLai Jiangshan mutex_unlock(&wq->mutex); 29669c5a2ba7STejun Heo } 29679c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 29689c5a2ba7STejun Heo 2969d6e89786SJohannes Berg static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, 2970d6e89786SJohannes Berg bool from_cancel) 2971baf59022STejun Heo { 2972baf59022STejun Heo struct worker *worker = NULL; 2973c9e7cf27STejun Heo struct worker_pool *pool; 2974112202d9STejun Heo struct pool_workqueue *pwq; 2975baf59022STejun Heo 2976baf59022STejun Heo might_sleep(); 2977baf59022STejun Heo 297824acfb71SThomas Gleixner rcu_read_lock(); 2979fa1b54e6STejun Heo pool = get_work_pool(work); 2980fa1b54e6STejun Heo if (!pool) { 298124acfb71SThomas Gleixner rcu_read_unlock(); 2982fa1b54e6STejun Heo return false; 2983fa1b54e6STejun Heo } 2984fa1b54e6STejun Heo 298524acfb71SThomas Gleixner spin_lock_irq(&pool->lock); 29860b3dae68SLai Jiangshan /* see the comment in try_to_grab_pending() with the same code */ 2987112202d9STejun Heo pwq = get_work_pwq(work); 2988112202d9STejun Heo if (pwq) { 2989112202d9STejun Heo if (unlikely(pwq->pool != pool)) 2990baf59022STejun Heo goto already_gone; 2991606a5020STejun Heo } else { 2992c9e7cf27STejun Heo worker = find_worker_executing_work(pool, work); 2993baf59022STejun Heo if (!worker) 2994baf59022STejun Heo goto already_gone; 2995112202d9STejun Heo pwq = worker->current_pwq; 2996606a5020STejun Heo } 2997baf59022STejun Heo 2998fca839c0STejun Heo check_flush_dependency(pwq->wq, work); 2999fca839c0STejun Heo 3000112202d9STejun Heo insert_wq_barrier(pwq, barr, work, worker); 3001d565ed63STejun Heo spin_unlock_irq(&pool->lock); 3002baf59022STejun Heo 3003e159489bSTejun Heo /* 3004a1d14934SPeter Zijlstra * Force a lock recursion deadlock when using flush_work() inside a 3005a1d14934SPeter Zijlstra * single-threaded or rescuer equipped workqueue. 3006a1d14934SPeter Zijlstra * 3007a1d14934SPeter Zijlstra * For single threaded workqueues the deadlock happens when the work 3008a1d14934SPeter Zijlstra * is after the work issuing the flush_work(). For rescuer equipped 3009a1d14934SPeter Zijlstra * workqueues the deadlock happens when the rescuer stalls, blocking 3010a1d14934SPeter Zijlstra * forward progress. 3011e159489bSTejun Heo */ 3012d6e89786SJohannes Berg if (!from_cancel && 3013d6e89786SJohannes Berg (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer)) { 3014112202d9STejun Heo lock_map_acquire(&pwq->wq->lockdep_map); 3015112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 3016a1d14934SPeter Zijlstra } 301724acfb71SThomas Gleixner rcu_read_unlock(); 3018baf59022STejun Heo return true; 3019baf59022STejun Heo already_gone: 3020d565ed63STejun Heo spin_unlock_irq(&pool->lock); 302124acfb71SThomas Gleixner rcu_read_unlock(); 3022baf59022STejun Heo return false; 3023baf59022STejun Heo } 3024baf59022STejun Heo 3025d6e89786SJohannes Berg static bool __flush_work(struct work_struct *work, bool from_cancel) 3026d6e89786SJohannes Berg { 3027d6e89786SJohannes Berg struct wq_barrier barr; 3028d6e89786SJohannes Berg 3029d6e89786SJohannes Berg if (WARN_ON(!wq_online)) 3030d6e89786SJohannes Berg return false; 3031d6e89786SJohannes Berg 30324d43d395STetsuo Handa if (WARN_ON(!work->func)) 30334d43d395STetsuo Handa return false; 30344d43d395STetsuo Handa 303587915adcSJohannes Berg if (!from_cancel) { 303687915adcSJohannes Berg lock_map_acquire(&work->lockdep_map); 303787915adcSJohannes Berg lock_map_release(&work->lockdep_map); 303887915adcSJohannes Berg } 303987915adcSJohannes Berg 3040d6e89786SJohannes Berg if (start_flush_work(work, &barr, from_cancel)) { 3041d6e89786SJohannes Berg wait_for_completion(&barr.done); 3042d6e89786SJohannes Berg destroy_work_on_stack(&barr.work); 3043d6e89786SJohannes Berg return true; 3044d6e89786SJohannes Berg } else { 3045d6e89786SJohannes Berg return false; 3046d6e89786SJohannes Berg } 3047d6e89786SJohannes Berg } 3048d6e89786SJohannes Berg 3049db700897SOleg Nesterov /** 3050401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 3051401a8d04STejun Heo * @work: the work to flush 3052db700897SOleg Nesterov * 3053606a5020STejun Heo * Wait until @work has finished execution. @work is guaranteed to be idle 3054606a5020STejun Heo * on return if it hasn't been requeued since flush started. 3055401a8d04STejun Heo * 3056d185af30SYacine Belkadi * Return: 3057401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 3058401a8d04STejun Heo * %false if it was already idle. 3059db700897SOleg Nesterov */ 3060401a8d04STejun Heo bool flush_work(struct work_struct *work) 3061db700897SOleg Nesterov { 3062d6e89786SJohannes Berg return __flush_work(work, false); 3063606a5020STejun Heo } 3064db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 3065db700897SOleg Nesterov 30668603e1b3STejun Heo struct cwt_wait { 3067ac6424b9SIngo Molnar wait_queue_entry_t wait; 30688603e1b3STejun Heo struct work_struct *work; 30698603e1b3STejun Heo }; 30708603e1b3STejun Heo 3071ac6424b9SIngo Molnar static int cwt_wakefn(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) 30728603e1b3STejun Heo { 30738603e1b3STejun Heo struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait); 30748603e1b3STejun Heo 30758603e1b3STejun Heo if (cwait->work != key) 30768603e1b3STejun Heo return 0; 30778603e1b3STejun Heo return autoremove_wake_function(wait, mode, sync, key); 30788603e1b3STejun Heo } 30798603e1b3STejun Heo 308036e227d2STejun Heo static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 3081401a8d04STejun Heo { 30828603e1b3STejun Heo static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq); 3083bbb68dfaSTejun Heo unsigned long flags; 30841f1f642eSOleg Nesterov int ret; 30851f1f642eSOleg Nesterov 30861f1f642eSOleg Nesterov do { 3087bbb68dfaSTejun Heo ret = try_to_grab_pending(work, is_dwork, &flags); 3088bbb68dfaSTejun Heo /* 30898603e1b3STejun Heo * If someone else is already canceling, wait for it to 30908603e1b3STejun Heo * finish. flush_work() doesn't work for PREEMPT_NONE 30918603e1b3STejun Heo * because we may get scheduled between @work's completion 30928603e1b3STejun Heo * and the other canceling task resuming and clearing 30938603e1b3STejun Heo * CANCELING - flush_work() will return false immediately 30948603e1b3STejun Heo * as @work is no longer busy, try_to_grab_pending() will 30958603e1b3STejun Heo * return -ENOENT as @work is still being canceled and the 30968603e1b3STejun Heo * other canceling task won't be able to clear CANCELING as 30978603e1b3STejun Heo * we're hogging the CPU. 30988603e1b3STejun Heo * 30998603e1b3STejun Heo * Let's wait for completion using a waitqueue. As this 31008603e1b3STejun Heo * may lead to the thundering herd problem, use a custom 31018603e1b3STejun Heo * wake function which matches @work along with exclusive 31028603e1b3STejun Heo * wait and wakeup. 3103bbb68dfaSTejun Heo */ 31048603e1b3STejun Heo if (unlikely(ret == -ENOENT)) { 31058603e1b3STejun Heo struct cwt_wait cwait; 31068603e1b3STejun Heo 31078603e1b3STejun Heo init_wait(&cwait.wait); 31088603e1b3STejun Heo cwait.wait.func = cwt_wakefn; 31098603e1b3STejun Heo cwait.work = work; 31108603e1b3STejun Heo 31118603e1b3STejun Heo prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait, 31128603e1b3STejun Heo TASK_UNINTERRUPTIBLE); 31138603e1b3STejun Heo if (work_is_canceling(work)) 31148603e1b3STejun Heo schedule(); 31158603e1b3STejun Heo finish_wait(&cancel_waitq, &cwait.wait); 31168603e1b3STejun Heo } 31171f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 31181f1f642eSOleg Nesterov 3119bbb68dfaSTejun Heo /* tell other tasks trying to grab @work to back off */ 3120bbb68dfaSTejun Heo mark_work_canceling(work); 3121bbb68dfaSTejun Heo local_irq_restore(flags); 3122bbb68dfaSTejun Heo 31233347fa09STejun Heo /* 31243347fa09STejun Heo * This allows canceling during early boot. We know that @work 31253347fa09STejun Heo * isn't executing. 31263347fa09STejun Heo */ 31273347fa09STejun Heo if (wq_online) 3128d6e89786SJohannes Berg __flush_work(work, true); 31293347fa09STejun Heo 31307a22ad75STejun Heo clear_work_data(work); 31318603e1b3STejun Heo 31328603e1b3STejun Heo /* 31338603e1b3STejun Heo * Paired with prepare_to_wait() above so that either 31348603e1b3STejun Heo * waitqueue_active() is visible here or !work_is_canceling() is 31358603e1b3STejun Heo * visible there. 31368603e1b3STejun Heo */ 31378603e1b3STejun Heo smp_mb(); 31388603e1b3STejun Heo if (waitqueue_active(&cancel_waitq)) 31398603e1b3STejun Heo __wake_up(&cancel_waitq, TASK_NORMAL, 1, work); 31408603e1b3STejun Heo 31411f1f642eSOleg Nesterov return ret; 31421f1f642eSOleg Nesterov } 31431f1f642eSOleg Nesterov 31446e84d644SOleg Nesterov /** 3145401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 3146401a8d04STejun Heo * @work: the work to cancel 31476e84d644SOleg Nesterov * 3148401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 3149401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 3150401a8d04STejun Heo * another workqueue. On return from this function, @work is 3151401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 31521f1f642eSOleg Nesterov * 3153401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 3154401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 31556e84d644SOleg Nesterov * 3156401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 31576e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 3158401a8d04STejun Heo * 3159d185af30SYacine Belkadi * Return: 3160401a8d04STejun Heo * %true if @work was pending, %false otherwise. 31616e84d644SOleg Nesterov */ 3162401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 31636e84d644SOleg Nesterov { 316436e227d2STejun Heo return __cancel_work_timer(work, false); 3165b89deed3SOleg Nesterov } 316628e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 3167b89deed3SOleg Nesterov 31686e84d644SOleg Nesterov /** 3169401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 3170401a8d04STejun Heo * @dwork: the delayed work to flush 31716e84d644SOleg Nesterov * 3172401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 3173401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 3174401a8d04STejun Heo * considers the last queueing instance of @dwork. 31751f1f642eSOleg Nesterov * 3176d185af30SYacine Belkadi * Return: 3177401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 3178401a8d04STejun Heo * %false if it was already idle. 31796e84d644SOleg Nesterov */ 3180401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 3181401a8d04STejun Heo { 31828930cabaSTejun Heo local_irq_disable(); 3183401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 318460c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 31858930cabaSTejun Heo local_irq_enable(); 3186401a8d04STejun Heo return flush_work(&dwork->work); 3187401a8d04STejun Heo } 3188401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 3189401a8d04STejun Heo 319005f0fe6bSTejun Heo /** 319105f0fe6bSTejun Heo * flush_rcu_work - wait for a rwork to finish executing the last queueing 319205f0fe6bSTejun Heo * @rwork: the rcu work to flush 319305f0fe6bSTejun Heo * 319405f0fe6bSTejun Heo * Return: 319505f0fe6bSTejun Heo * %true if flush_rcu_work() waited for the work to finish execution, 319605f0fe6bSTejun Heo * %false if it was already idle. 319705f0fe6bSTejun Heo */ 319805f0fe6bSTejun Heo bool flush_rcu_work(struct rcu_work *rwork) 319905f0fe6bSTejun Heo { 320005f0fe6bSTejun Heo if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) { 320105f0fe6bSTejun Heo rcu_barrier(); 320205f0fe6bSTejun Heo flush_work(&rwork->work); 320305f0fe6bSTejun Heo return true; 320405f0fe6bSTejun Heo } else { 320505f0fe6bSTejun Heo return flush_work(&rwork->work); 320605f0fe6bSTejun Heo } 320705f0fe6bSTejun Heo } 320805f0fe6bSTejun Heo EXPORT_SYMBOL(flush_rcu_work); 320905f0fe6bSTejun Heo 3210f72b8792SJens Axboe static bool __cancel_work(struct work_struct *work, bool is_dwork) 3211f72b8792SJens Axboe { 3212f72b8792SJens Axboe unsigned long flags; 3213f72b8792SJens Axboe int ret; 3214f72b8792SJens Axboe 3215f72b8792SJens Axboe do { 3216f72b8792SJens Axboe ret = try_to_grab_pending(work, is_dwork, &flags); 3217f72b8792SJens Axboe } while (unlikely(ret == -EAGAIN)); 3218f72b8792SJens Axboe 3219f72b8792SJens Axboe if (unlikely(ret < 0)) 3220f72b8792SJens Axboe return false; 3221f72b8792SJens Axboe 3222f72b8792SJens Axboe set_work_pool_and_clear_pending(work, get_work_pool_id(work)); 3223f72b8792SJens Axboe local_irq_restore(flags); 3224f72b8792SJens Axboe return ret; 3225f72b8792SJens Axboe } 3226f72b8792SJens Axboe 3227401a8d04STejun Heo /** 322857b30ae7STejun Heo * cancel_delayed_work - cancel a delayed work 322957b30ae7STejun Heo * @dwork: delayed_work to cancel 323009383498STejun Heo * 3231d185af30SYacine Belkadi * Kill off a pending delayed_work. 3232d185af30SYacine Belkadi * 3233d185af30SYacine Belkadi * Return: %true if @dwork was pending and canceled; %false if it wasn't 3234d185af30SYacine Belkadi * pending. 3235d185af30SYacine Belkadi * 3236d185af30SYacine Belkadi * Note: 3237d185af30SYacine Belkadi * The work callback function may still be running on return, unless 3238d185af30SYacine Belkadi * it returns %true and the work doesn't re-arm itself. Explicitly flush or 3239d185af30SYacine Belkadi * use cancel_delayed_work_sync() to wait on it. 324009383498STejun Heo * 324157b30ae7STejun Heo * This function is safe to call from any context including IRQ handler. 324209383498STejun Heo */ 324357b30ae7STejun Heo bool cancel_delayed_work(struct delayed_work *dwork) 324409383498STejun Heo { 3245f72b8792SJens Axboe return __cancel_work(&dwork->work, true); 324609383498STejun Heo } 324757b30ae7STejun Heo EXPORT_SYMBOL(cancel_delayed_work); 324809383498STejun Heo 324909383498STejun Heo /** 3250401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 3251401a8d04STejun Heo * @dwork: the delayed work cancel 3252401a8d04STejun Heo * 3253401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 3254401a8d04STejun Heo * 3255d185af30SYacine Belkadi * Return: 3256401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 3257401a8d04STejun Heo */ 3258401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 32596e84d644SOleg Nesterov { 326036e227d2STejun Heo return __cancel_work_timer(&dwork->work, true); 32616e84d644SOleg Nesterov } 3262f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 32631da177e4SLinus Torvalds 32640fcb78c2SRolf Eike Beer /** 326531ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 3266b6136773SAndrew Morton * @func: the function to call 3267b6136773SAndrew Morton * 326831ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 326931ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 3270b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 327131ddd871STejun Heo * 3272d185af30SYacine Belkadi * Return: 327331ddd871STejun Heo * 0 on success, -errno on failure. 3274b6136773SAndrew Morton */ 327565f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 327615316ba8SChristoph Lameter { 327715316ba8SChristoph Lameter int cpu; 327838f51568SNamhyung Kim struct work_struct __percpu *works; 327915316ba8SChristoph Lameter 3280b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 3281b6136773SAndrew Morton if (!works) 328215316ba8SChristoph Lameter return -ENOMEM; 3283b6136773SAndrew Morton 328495402b38SGautham R Shenoy get_online_cpus(); 328593981800STejun Heo 328615316ba8SChristoph Lameter for_each_online_cpu(cpu) { 32879bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 32889bfb1839SIngo Molnar 32899bfb1839SIngo Molnar INIT_WORK(work, func); 32908de6d308SOleg Nesterov schedule_work_on(cpu, work); 329115316ba8SChristoph Lameter } 329293981800STejun Heo 329393981800STejun Heo for_each_online_cpu(cpu) 32948616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 329593981800STejun Heo 329695402b38SGautham R Shenoy put_online_cpus(); 3297b6136773SAndrew Morton free_percpu(works); 329815316ba8SChristoph Lameter return 0; 329915316ba8SChristoph Lameter } 330015316ba8SChristoph Lameter 3301eef6a7d5SAlan Stern /** 33021fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 33031fa44ecaSJames Bottomley * @fn: the function to execute 33041fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 33051fa44ecaSJames Bottomley * be available when the work executes) 33061fa44ecaSJames Bottomley * 33071fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 33081fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 33091fa44ecaSJames Bottomley * 3310d185af30SYacine Belkadi * Return: 0 - function was executed 33111fa44ecaSJames Bottomley * 1 - function was scheduled for execution 33121fa44ecaSJames Bottomley */ 331365f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 33141fa44ecaSJames Bottomley { 33151fa44ecaSJames Bottomley if (!in_interrupt()) { 331665f27f38SDavid Howells fn(&ew->work); 33171fa44ecaSJames Bottomley return 0; 33181fa44ecaSJames Bottomley } 33191fa44ecaSJames Bottomley 332065f27f38SDavid Howells INIT_WORK(&ew->work, fn); 33211fa44ecaSJames Bottomley schedule_work(&ew->work); 33221fa44ecaSJames Bottomley 33231fa44ecaSJames Bottomley return 1; 33241fa44ecaSJames Bottomley } 33251fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 33261fa44ecaSJames Bottomley 33277a4e344cSTejun Heo /** 33287a4e344cSTejun Heo * free_workqueue_attrs - free a workqueue_attrs 33297a4e344cSTejun Heo * @attrs: workqueue_attrs to free 33307a4e344cSTejun Heo * 33317a4e344cSTejun Heo * Undo alloc_workqueue_attrs(). 33327a4e344cSTejun Heo */ 3333513c98d0SDaniel Jordan void free_workqueue_attrs(struct workqueue_attrs *attrs) 33347a4e344cSTejun Heo { 33357a4e344cSTejun Heo if (attrs) { 33367a4e344cSTejun Heo free_cpumask_var(attrs->cpumask); 33377a4e344cSTejun Heo kfree(attrs); 33387a4e344cSTejun Heo } 33397a4e344cSTejun Heo } 33407a4e344cSTejun Heo 33417a4e344cSTejun Heo /** 33427a4e344cSTejun Heo * alloc_workqueue_attrs - allocate a workqueue_attrs 33437a4e344cSTejun Heo * 33447a4e344cSTejun Heo * Allocate a new workqueue_attrs, initialize with default settings and 3345d185af30SYacine Belkadi * return it. 3346d185af30SYacine Belkadi * 3347d185af30SYacine Belkadi * Return: The allocated new workqueue_attr on success. %NULL on failure. 33487a4e344cSTejun Heo */ 3349513c98d0SDaniel Jordan struct workqueue_attrs *alloc_workqueue_attrs(void) 33507a4e344cSTejun Heo { 33517a4e344cSTejun Heo struct workqueue_attrs *attrs; 33527a4e344cSTejun Heo 3353be69d00dSThomas Gleixner attrs = kzalloc(sizeof(*attrs), GFP_KERNEL); 33547a4e344cSTejun Heo if (!attrs) 33557a4e344cSTejun Heo goto fail; 3356be69d00dSThomas Gleixner if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL)) 33577a4e344cSTejun Heo goto fail; 33587a4e344cSTejun Heo 335913e2e556STejun Heo cpumask_copy(attrs->cpumask, cpu_possible_mask); 33607a4e344cSTejun Heo return attrs; 33617a4e344cSTejun Heo fail: 33627a4e344cSTejun Heo free_workqueue_attrs(attrs); 33637a4e344cSTejun Heo return NULL; 33647a4e344cSTejun Heo } 33657a4e344cSTejun Heo 336629c91e99STejun Heo static void copy_workqueue_attrs(struct workqueue_attrs *to, 336729c91e99STejun Heo const struct workqueue_attrs *from) 336829c91e99STejun Heo { 336929c91e99STejun Heo to->nice = from->nice; 337029c91e99STejun Heo cpumask_copy(to->cpumask, from->cpumask); 33712865a8fbSShaohua Li /* 33722865a8fbSShaohua Li * Unlike hash and equality test, this function doesn't ignore 33732865a8fbSShaohua Li * ->no_numa as it is used for both pool and wq attrs. Instead, 33742865a8fbSShaohua Li * get_unbound_pool() explicitly clears ->no_numa after copying. 33752865a8fbSShaohua Li */ 33762865a8fbSShaohua Li to->no_numa = from->no_numa; 337729c91e99STejun Heo } 337829c91e99STejun Heo 337929c91e99STejun Heo /* hash value of the content of @attr */ 338029c91e99STejun Heo static u32 wqattrs_hash(const struct workqueue_attrs *attrs) 338129c91e99STejun Heo { 338229c91e99STejun Heo u32 hash = 0; 338329c91e99STejun Heo 338429c91e99STejun Heo hash = jhash_1word(attrs->nice, hash); 338513e2e556STejun Heo hash = jhash(cpumask_bits(attrs->cpumask), 338613e2e556STejun Heo BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); 338729c91e99STejun Heo return hash; 338829c91e99STejun Heo } 338929c91e99STejun Heo 339029c91e99STejun Heo /* content equality test */ 339129c91e99STejun Heo static bool wqattrs_equal(const struct workqueue_attrs *a, 339229c91e99STejun Heo const struct workqueue_attrs *b) 339329c91e99STejun Heo { 339429c91e99STejun Heo if (a->nice != b->nice) 339529c91e99STejun Heo return false; 339629c91e99STejun Heo if (!cpumask_equal(a->cpumask, b->cpumask)) 339729c91e99STejun Heo return false; 339829c91e99STejun Heo return true; 339929c91e99STejun Heo } 340029c91e99STejun Heo 34017a4e344cSTejun Heo /** 34027a4e344cSTejun Heo * init_worker_pool - initialize a newly zalloc'd worker_pool 34037a4e344cSTejun Heo * @pool: worker_pool to initialize 34047a4e344cSTejun Heo * 3405402dd89dSShailendra Verma * Initialize a newly zalloc'd @pool. It also allocates @pool->attrs. 3406d185af30SYacine Belkadi * 3407d185af30SYacine Belkadi * Return: 0 on success, -errno on failure. Even on failure, all fields 340829c91e99STejun Heo * inside @pool proper are initialized and put_unbound_pool() can be called 340929c91e99STejun Heo * on @pool safely to release it. 34107a4e344cSTejun Heo */ 34117a4e344cSTejun Heo static int init_worker_pool(struct worker_pool *pool) 34124e1a1f9aSTejun Heo { 34134e1a1f9aSTejun Heo spin_lock_init(&pool->lock); 341429c91e99STejun Heo pool->id = -1; 341529c91e99STejun Heo pool->cpu = -1; 3416f3f90ad4STejun Heo pool->node = NUMA_NO_NODE; 34174e1a1f9aSTejun Heo pool->flags |= POOL_DISASSOCIATED; 341882607adcSTejun Heo pool->watchdog_ts = jiffies; 34194e1a1f9aSTejun Heo INIT_LIST_HEAD(&pool->worklist); 34204e1a1f9aSTejun Heo INIT_LIST_HEAD(&pool->idle_list); 34214e1a1f9aSTejun Heo hash_init(pool->busy_hash); 34224e1a1f9aSTejun Heo 342332a6c723SKees Cook timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE); 34244e1a1f9aSTejun Heo 342532a6c723SKees Cook timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0); 34264e1a1f9aSTejun Heo 3427da028469SLai Jiangshan INIT_LIST_HEAD(&pool->workers); 34287a4e344cSTejun Heo 34297cda9aaeSLai Jiangshan ida_init(&pool->worker_ida); 343029c91e99STejun Heo INIT_HLIST_NODE(&pool->hash_node); 343129c91e99STejun Heo pool->refcnt = 1; 343229c91e99STejun Heo 343329c91e99STejun Heo /* shouldn't fail above this point */ 3434be69d00dSThomas Gleixner pool->attrs = alloc_workqueue_attrs(); 34357a4e344cSTejun Heo if (!pool->attrs) 34367a4e344cSTejun Heo return -ENOMEM; 34377a4e344cSTejun Heo return 0; 34384e1a1f9aSTejun Heo } 34394e1a1f9aSTejun Heo 3440669de8bdSBart Van Assche #ifdef CONFIG_LOCKDEP 3441669de8bdSBart Van Assche static void wq_init_lockdep(struct workqueue_struct *wq) 3442669de8bdSBart Van Assche { 3443669de8bdSBart Van Assche char *lock_name; 3444669de8bdSBart Van Assche 3445669de8bdSBart Van Assche lockdep_register_key(&wq->key); 3446669de8bdSBart Van Assche lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name); 3447669de8bdSBart Van Assche if (!lock_name) 3448669de8bdSBart Van Assche lock_name = wq->name; 344969a106c0SQian Cai 345069a106c0SQian Cai wq->lock_name = lock_name; 3451669de8bdSBart Van Assche lockdep_init_map(&wq->lockdep_map, lock_name, &wq->key, 0); 3452669de8bdSBart Van Assche } 3453669de8bdSBart Van Assche 3454669de8bdSBart Van Assche static void wq_unregister_lockdep(struct workqueue_struct *wq) 3455669de8bdSBart Van Assche { 3456669de8bdSBart Van Assche lockdep_unregister_key(&wq->key); 3457669de8bdSBart Van Assche } 3458669de8bdSBart Van Assche 3459669de8bdSBart Van Assche static void wq_free_lockdep(struct workqueue_struct *wq) 3460669de8bdSBart Van Assche { 3461669de8bdSBart Van Assche if (wq->lock_name != wq->name) 3462669de8bdSBart Van Assche kfree(wq->lock_name); 3463669de8bdSBart Van Assche } 3464669de8bdSBart Van Assche #else 3465669de8bdSBart Van Assche static void wq_init_lockdep(struct workqueue_struct *wq) 3466669de8bdSBart Van Assche { 3467669de8bdSBart Van Assche } 3468669de8bdSBart Van Assche 3469669de8bdSBart Van Assche static void wq_unregister_lockdep(struct workqueue_struct *wq) 3470669de8bdSBart Van Assche { 3471669de8bdSBart Van Assche } 3472669de8bdSBart Van Assche 3473669de8bdSBart Van Assche static void wq_free_lockdep(struct workqueue_struct *wq) 3474669de8bdSBart Van Assche { 3475669de8bdSBart Van Assche } 3476669de8bdSBart Van Assche #endif 3477669de8bdSBart Van Assche 3478e2dca7adSTejun Heo static void rcu_free_wq(struct rcu_head *rcu) 3479e2dca7adSTejun Heo { 3480e2dca7adSTejun Heo struct workqueue_struct *wq = 3481e2dca7adSTejun Heo container_of(rcu, struct workqueue_struct, rcu); 3482e2dca7adSTejun Heo 3483669de8bdSBart Van Assche wq_free_lockdep(wq); 3484669de8bdSBart Van Assche 3485e2dca7adSTejun Heo if (!(wq->flags & WQ_UNBOUND)) 3486e2dca7adSTejun Heo free_percpu(wq->cpu_pwqs); 3487e2dca7adSTejun Heo else 3488e2dca7adSTejun Heo free_workqueue_attrs(wq->unbound_attrs); 3489e2dca7adSTejun Heo 3490e2dca7adSTejun Heo kfree(wq->rescuer); 3491e2dca7adSTejun Heo kfree(wq); 3492e2dca7adSTejun Heo } 3493e2dca7adSTejun Heo 349429c91e99STejun Heo static void rcu_free_pool(struct rcu_head *rcu) 349529c91e99STejun Heo { 349629c91e99STejun Heo struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); 349729c91e99STejun Heo 34987cda9aaeSLai Jiangshan ida_destroy(&pool->worker_ida); 349929c91e99STejun Heo free_workqueue_attrs(pool->attrs); 350029c91e99STejun Heo kfree(pool); 350129c91e99STejun Heo } 350229c91e99STejun Heo 350329c91e99STejun Heo /** 350429c91e99STejun Heo * put_unbound_pool - put a worker_pool 350529c91e99STejun Heo * @pool: worker_pool to put 350629c91e99STejun Heo * 350724acfb71SThomas Gleixner * Put @pool. If its refcnt reaches zero, it gets destroyed in RCU 3508c5aa87bbSTejun Heo * safe manner. get_unbound_pool() calls this function on its failure path 3509c5aa87bbSTejun Heo * and this function should be able to release pools which went through, 3510c5aa87bbSTejun Heo * successfully or not, init_worker_pool(). 3511a892caccSTejun Heo * 3512a892caccSTejun Heo * Should be called with wq_pool_mutex held. 351329c91e99STejun Heo */ 351429c91e99STejun Heo static void put_unbound_pool(struct worker_pool *pool) 351529c91e99STejun Heo { 351660f5a4bcSLai Jiangshan DECLARE_COMPLETION_ONSTACK(detach_completion); 351729c91e99STejun Heo struct worker *worker; 351829c91e99STejun Heo 3519a892caccSTejun Heo lockdep_assert_held(&wq_pool_mutex); 3520a892caccSTejun Heo 3521a892caccSTejun Heo if (--pool->refcnt) 352229c91e99STejun Heo return; 352329c91e99STejun Heo 352429c91e99STejun Heo /* sanity checks */ 352561d0fbb4SLai Jiangshan if (WARN_ON(!(pool->cpu < 0)) || 3526a892caccSTejun Heo WARN_ON(!list_empty(&pool->worklist))) 352729c91e99STejun Heo return; 352829c91e99STejun Heo 352929c91e99STejun Heo /* release id and unhash */ 353029c91e99STejun Heo if (pool->id >= 0) 353129c91e99STejun Heo idr_remove(&worker_pool_idr, pool->id); 353229c91e99STejun Heo hash_del(&pool->hash_node); 353329c91e99STejun Heo 3534c5aa87bbSTejun Heo /* 3535692b4825STejun Heo * Become the manager and destroy all workers. This prevents 3536692b4825STejun Heo * @pool's workers from blocking on attach_mutex. We're the last 3537692b4825STejun Heo * manager and @pool gets freed with the flag set. 3538c5aa87bbSTejun Heo */ 353960f5a4bcSLai Jiangshan spin_lock_irq(&pool->lock); 3540692b4825STejun Heo wait_event_lock_irq(wq_manager_wait, 3541692b4825STejun Heo !(pool->flags & POOL_MANAGER_ACTIVE), pool->lock); 3542692b4825STejun Heo pool->flags |= POOL_MANAGER_ACTIVE; 3543692b4825STejun Heo 35441037de36SLai Jiangshan while ((worker = first_idle_worker(pool))) 354529c91e99STejun Heo destroy_worker(worker); 354629c91e99STejun Heo WARN_ON(pool->nr_workers || pool->nr_idle); 354729c91e99STejun Heo spin_unlock_irq(&pool->lock); 354860f5a4bcSLai Jiangshan 35491258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 3550da028469SLai Jiangshan if (!list_empty(&pool->workers)) 355160f5a4bcSLai Jiangshan pool->detach_completion = &detach_completion; 35521258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 355360f5a4bcSLai Jiangshan 355460f5a4bcSLai Jiangshan if (pool->detach_completion) 355560f5a4bcSLai Jiangshan wait_for_completion(pool->detach_completion); 355660f5a4bcSLai Jiangshan 355729c91e99STejun Heo /* shut down the timers */ 355829c91e99STejun Heo del_timer_sync(&pool->idle_timer); 355929c91e99STejun Heo del_timer_sync(&pool->mayday_timer); 356029c91e99STejun Heo 356124acfb71SThomas Gleixner /* RCU protected to allow dereferences from get_work_pool() */ 356225b00775SPaul E. McKenney call_rcu(&pool->rcu, rcu_free_pool); 356329c91e99STejun Heo } 356429c91e99STejun Heo 356529c91e99STejun Heo /** 356629c91e99STejun Heo * get_unbound_pool - get a worker_pool with the specified attributes 356729c91e99STejun Heo * @attrs: the attributes of the worker_pool to get 356829c91e99STejun Heo * 356929c91e99STejun Heo * Obtain a worker_pool which has the same attributes as @attrs, bump the 357029c91e99STejun Heo * reference count and return it. If there already is a matching 357129c91e99STejun Heo * worker_pool, it will be used; otherwise, this function attempts to 3572d185af30SYacine Belkadi * create a new one. 3573a892caccSTejun Heo * 3574a892caccSTejun Heo * Should be called with wq_pool_mutex held. 3575d185af30SYacine Belkadi * 3576d185af30SYacine Belkadi * Return: On success, a worker_pool with the same attributes as @attrs. 3577d185af30SYacine Belkadi * On failure, %NULL. 357829c91e99STejun Heo */ 357929c91e99STejun Heo static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) 358029c91e99STejun Heo { 358129c91e99STejun Heo u32 hash = wqattrs_hash(attrs); 358229c91e99STejun Heo struct worker_pool *pool; 3583f3f90ad4STejun Heo int node; 3584e2273584SXunlei Pang int target_node = NUMA_NO_NODE; 358529c91e99STejun Heo 3586a892caccSTejun Heo lockdep_assert_held(&wq_pool_mutex); 358729c91e99STejun Heo 358829c91e99STejun Heo /* do we already have a matching pool? */ 358929c91e99STejun Heo hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { 359029c91e99STejun Heo if (wqattrs_equal(pool->attrs, attrs)) { 359129c91e99STejun Heo pool->refcnt++; 35923fb1823cSLai Jiangshan return pool; 359329c91e99STejun Heo } 359429c91e99STejun Heo } 359529c91e99STejun Heo 3596e2273584SXunlei Pang /* if cpumask is contained inside a NUMA node, we belong to that node */ 3597e2273584SXunlei Pang if (wq_numa_enabled) { 3598e2273584SXunlei Pang for_each_node(node) { 3599e2273584SXunlei Pang if (cpumask_subset(attrs->cpumask, 3600e2273584SXunlei Pang wq_numa_possible_cpumask[node])) { 3601e2273584SXunlei Pang target_node = node; 3602e2273584SXunlei Pang break; 3603e2273584SXunlei Pang } 3604e2273584SXunlei Pang } 3605e2273584SXunlei Pang } 3606e2273584SXunlei Pang 360729c91e99STejun Heo /* nope, create a new one */ 3608e2273584SXunlei Pang pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, target_node); 360929c91e99STejun Heo if (!pool || init_worker_pool(pool) < 0) 361029c91e99STejun Heo goto fail; 361129c91e99STejun Heo 36128864b4e5STejun Heo lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ 361329c91e99STejun Heo copy_workqueue_attrs(pool->attrs, attrs); 3614e2273584SXunlei Pang pool->node = target_node; 361529c91e99STejun Heo 36162865a8fbSShaohua Li /* 36172865a8fbSShaohua Li * no_numa isn't a worker_pool attribute, always clear it. See 36182865a8fbSShaohua Li * 'struct workqueue_attrs' comments for detail. 36192865a8fbSShaohua Li */ 36202865a8fbSShaohua Li pool->attrs->no_numa = false; 36212865a8fbSShaohua Li 362229c91e99STejun Heo if (worker_pool_assign_id(pool) < 0) 362329c91e99STejun Heo goto fail; 362429c91e99STejun Heo 362529c91e99STejun Heo /* create and start the initial worker */ 36263347fa09STejun Heo if (wq_online && !create_worker(pool)) 362729c91e99STejun Heo goto fail; 362829c91e99STejun Heo 362929c91e99STejun Heo /* install */ 363029c91e99STejun Heo hash_add(unbound_pool_hash, &pool->hash_node, hash); 36313fb1823cSLai Jiangshan 363229c91e99STejun Heo return pool; 363329c91e99STejun Heo fail: 363429c91e99STejun Heo if (pool) 363529c91e99STejun Heo put_unbound_pool(pool); 363629c91e99STejun Heo return NULL; 363729c91e99STejun Heo } 363829c91e99STejun Heo 36398864b4e5STejun Heo static void rcu_free_pwq(struct rcu_head *rcu) 36408864b4e5STejun Heo { 36418864b4e5STejun Heo kmem_cache_free(pwq_cache, 36428864b4e5STejun Heo container_of(rcu, struct pool_workqueue, rcu)); 36438864b4e5STejun Heo } 36448864b4e5STejun Heo 36458864b4e5STejun Heo /* 36468864b4e5STejun Heo * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt 36478864b4e5STejun Heo * and needs to be destroyed. 36488864b4e5STejun Heo */ 36498864b4e5STejun Heo static void pwq_unbound_release_workfn(struct work_struct *work) 36508864b4e5STejun Heo { 36518864b4e5STejun Heo struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, 36528864b4e5STejun Heo unbound_release_work); 36538864b4e5STejun Heo struct workqueue_struct *wq = pwq->wq; 36548864b4e5STejun Heo struct worker_pool *pool = pwq->pool; 3655bc0caf09STejun Heo bool is_last; 36568864b4e5STejun Heo 36578864b4e5STejun Heo if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) 36588864b4e5STejun Heo return; 36598864b4e5STejun Heo 36603c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 36618864b4e5STejun Heo list_del_rcu(&pwq->pwqs_node); 3662bc0caf09STejun Heo is_last = list_empty(&wq->pwqs); 36633c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 36648864b4e5STejun Heo 3665a892caccSTejun Heo mutex_lock(&wq_pool_mutex); 36668864b4e5STejun Heo put_unbound_pool(pool); 3667a892caccSTejun Heo mutex_unlock(&wq_pool_mutex); 3668a892caccSTejun Heo 366925b00775SPaul E. McKenney call_rcu(&pwq->rcu, rcu_free_pwq); 36708864b4e5STejun Heo 36718864b4e5STejun Heo /* 36728864b4e5STejun Heo * If we're the last pwq going away, @wq is already dead and no one 3673e2dca7adSTejun Heo * is gonna access it anymore. Schedule RCU free. 36748864b4e5STejun Heo */ 3675669de8bdSBart Van Assche if (is_last) { 3676669de8bdSBart Van Assche wq_unregister_lockdep(wq); 367725b00775SPaul E. McKenney call_rcu(&wq->rcu, rcu_free_wq); 36786029a918STejun Heo } 3679669de8bdSBart Van Assche } 36808864b4e5STejun Heo 36810fbd95aaSTejun Heo /** 3682699ce097STejun Heo * pwq_adjust_max_active - update a pwq's max_active to the current setting 36830fbd95aaSTejun Heo * @pwq: target pool_workqueue 36840fbd95aaSTejun Heo * 3685699ce097STejun Heo * If @pwq isn't freezing, set @pwq->max_active to the associated 3686699ce097STejun Heo * workqueue's saved_max_active and activate delayed work items 3687699ce097STejun Heo * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. 36880fbd95aaSTejun Heo */ 3689699ce097STejun Heo static void pwq_adjust_max_active(struct pool_workqueue *pwq) 36900fbd95aaSTejun Heo { 3691699ce097STejun Heo struct workqueue_struct *wq = pwq->wq; 3692699ce097STejun Heo bool freezable = wq->flags & WQ_FREEZABLE; 36933347fa09STejun Heo unsigned long flags; 3694699ce097STejun Heo 3695699ce097STejun Heo /* for @wq->saved_max_active */ 3696a357fc03SLai Jiangshan lockdep_assert_held(&wq->mutex); 3697699ce097STejun Heo 3698699ce097STejun Heo /* fast exit for non-freezable wqs */ 3699699ce097STejun Heo if (!freezable && pwq->max_active == wq->saved_max_active) 3700699ce097STejun Heo return; 3701699ce097STejun Heo 37023347fa09STejun Heo /* this function can be called during early boot w/ irq disabled */ 37033347fa09STejun Heo spin_lock_irqsave(&pwq->pool->lock, flags); 3704699ce097STejun Heo 370574b414eaSLai Jiangshan /* 370674b414eaSLai Jiangshan * During [un]freezing, the caller is responsible for ensuring that 370774b414eaSLai Jiangshan * this function is called at least once after @workqueue_freezing 370874b414eaSLai Jiangshan * is updated and visible. 370974b414eaSLai Jiangshan */ 371074b414eaSLai Jiangshan if (!freezable || !workqueue_freezing) { 3711699ce097STejun Heo pwq->max_active = wq->saved_max_active; 37120fbd95aaSTejun Heo 37130fbd95aaSTejun Heo while (!list_empty(&pwq->delayed_works) && 37140fbd95aaSTejun Heo pwq->nr_active < pwq->max_active) 37150fbd95aaSTejun Heo pwq_activate_first_delayed(pwq); 3716951a078aSLai Jiangshan 3717951a078aSLai Jiangshan /* 3718951a078aSLai Jiangshan * Need to kick a worker after thawed or an unbound wq's 3719951a078aSLai Jiangshan * max_active is bumped. It's a slow path. Do it always. 3720951a078aSLai Jiangshan */ 3721951a078aSLai Jiangshan wake_up_worker(pwq->pool); 3722699ce097STejun Heo } else { 3723699ce097STejun Heo pwq->max_active = 0; 3724699ce097STejun Heo } 3725699ce097STejun Heo 37263347fa09STejun Heo spin_unlock_irqrestore(&pwq->pool->lock, flags); 37270fbd95aaSTejun Heo } 37280fbd95aaSTejun Heo 3729e50aba9aSTejun Heo /* initialize newly alloced @pwq which is associated with @wq and @pool */ 3730f147f29eSTejun Heo static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, 3731f147f29eSTejun Heo struct worker_pool *pool) 3732d2c1d404STejun Heo { 3733d2c1d404STejun Heo BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); 3734d2c1d404STejun Heo 3735e50aba9aSTejun Heo memset(pwq, 0, sizeof(*pwq)); 3736e50aba9aSTejun Heo 3737d2c1d404STejun Heo pwq->pool = pool; 3738d2c1d404STejun Heo pwq->wq = wq; 3739d2c1d404STejun Heo pwq->flush_color = -1; 37408864b4e5STejun Heo pwq->refcnt = 1; 3741d2c1d404STejun Heo INIT_LIST_HEAD(&pwq->delayed_works); 37421befcf30STejun Heo INIT_LIST_HEAD(&pwq->pwqs_node); 3743d2c1d404STejun Heo INIT_LIST_HEAD(&pwq->mayday_node); 37448864b4e5STejun Heo INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); 3745f147f29eSTejun Heo } 3746d2c1d404STejun Heo 3747f147f29eSTejun Heo /* sync @pwq with the current state of its associated wq and link it */ 37481befcf30STejun Heo static void link_pwq(struct pool_workqueue *pwq) 3749f147f29eSTejun Heo { 3750f147f29eSTejun Heo struct workqueue_struct *wq = pwq->wq; 3751f147f29eSTejun Heo 3752f147f29eSTejun Heo lockdep_assert_held(&wq->mutex); 375375ccf595STejun Heo 37541befcf30STejun Heo /* may be called multiple times, ignore if already linked */ 37551befcf30STejun Heo if (!list_empty(&pwq->pwqs_node)) 37561befcf30STejun Heo return; 37571befcf30STejun Heo 375829b1cb41SLai Jiangshan /* set the matching work_color */ 375975ccf595STejun Heo pwq->work_color = wq->work_color; 3760983ca25eSTejun Heo 3761983ca25eSTejun Heo /* sync max_active to the current setting */ 3762983ca25eSTejun Heo pwq_adjust_max_active(pwq); 3763983ca25eSTejun Heo 3764983ca25eSTejun Heo /* link in @pwq */ 37659e8cd2f5STejun Heo list_add_rcu(&pwq->pwqs_node, &wq->pwqs); 3766df2d5ae4STejun Heo } 37676029a918STejun Heo 3768f147f29eSTejun Heo /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ 3769f147f29eSTejun Heo static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, 3770f147f29eSTejun Heo const struct workqueue_attrs *attrs) 3771f147f29eSTejun Heo { 3772f147f29eSTejun Heo struct worker_pool *pool; 3773f147f29eSTejun Heo struct pool_workqueue *pwq; 3774f147f29eSTejun Heo 3775f147f29eSTejun Heo lockdep_assert_held(&wq_pool_mutex); 3776f147f29eSTejun Heo 3777f147f29eSTejun Heo pool = get_unbound_pool(attrs); 3778f147f29eSTejun Heo if (!pool) 3779f147f29eSTejun Heo return NULL; 3780f147f29eSTejun Heo 3781e50aba9aSTejun Heo pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); 3782f147f29eSTejun Heo if (!pwq) { 3783f147f29eSTejun Heo put_unbound_pool(pool); 3784f147f29eSTejun Heo return NULL; 3785f147f29eSTejun Heo } 3786f147f29eSTejun Heo 3787f147f29eSTejun Heo init_pwq(pwq, wq, pool); 3788f147f29eSTejun Heo return pwq; 3789d2c1d404STejun Heo } 3790d2c1d404STejun Heo 37914c16bd32STejun Heo /** 379230186c6fSGong Zhaogang * wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node 3793042f7df1SLai Jiangshan * @attrs: the wq_attrs of the default pwq of the target workqueue 37944c16bd32STejun Heo * @node: the target NUMA node 37954c16bd32STejun Heo * @cpu_going_down: if >= 0, the CPU to consider as offline 37964c16bd32STejun Heo * @cpumask: outarg, the resulting cpumask 37974c16bd32STejun Heo * 37984c16bd32STejun Heo * Calculate the cpumask a workqueue with @attrs should use on @node. If 37994c16bd32STejun Heo * @cpu_going_down is >= 0, that cpu is considered offline during 3800d185af30SYacine Belkadi * calculation. The result is stored in @cpumask. 38014c16bd32STejun Heo * 38024c16bd32STejun Heo * If NUMA affinity is not enabled, @attrs->cpumask is always used. If 38034c16bd32STejun Heo * enabled and @node has online CPUs requested by @attrs, the returned 38044c16bd32STejun Heo * cpumask is the intersection of the possible CPUs of @node and 38054c16bd32STejun Heo * @attrs->cpumask. 38064c16bd32STejun Heo * 38074c16bd32STejun Heo * The caller is responsible for ensuring that the cpumask of @node stays 38084c16bd32STejun Heo * stable. 3809d185af30SYacine Belkadi * 3810d185af30SYacine Belkadi * Return: %true if the resulting @cpumask is different from @attrs->cpumask, 3811d185af30SYacine Belkadi * %false if equal. 38124c16bd32STejun Heo */ 38134c16bd32STejun Heo static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, 38144c16bd32STejun Heo int cpu_going_down, cpumask_t *cpumask) 38154c16bd32STejun Heo { 3816d55262c4STejun Heo if (!wq_numa_enabled || attrs->no_numa) 38174c16bd32STejun Heo goto use_dfl; 38184c16bd32STejun Heo 38194c16bd32STejun Heo /* does @node have any online CPUs @attrs wants? */ 38204c16bd32STejun Heo cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); 38214c16bd32STejun Heo if (cpu_going_down >= 0) 38224c16bd32STejun Heo cpumask_clear_cpu(cpu_going_down, cpumask); 38234c16bd32STejun Heo 38244c16bd32STejun Heo if (cpumask_empty(cpumask)) 38254c16bd32STejun Heo goto use_dfl; 38264c16bd32STejun Heo 38274c16bd32STejun Heo /* yeap, return possible CPUs in @node that @attrs wants */ 38284c16bd32STejun Heo cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); 38291ad0f0a7SMichael Bringmann 38301ad0f0a7SMichael Bringmann if (cpumask_empty(cpumask)) { 38311ad0f0a7SMichael Bringmann pr_warn_once("WARNING: workqueue cpumask: online intersect > " 38321ad0f0a7SMichael Bringmann "possible intersect\n"); 38331ad0f0a7SMichael Bringmann return false; 38341ad0f0a7SMichael Bringmann } 38351ad0f0a7SMichael Bringmann 38364c16bd32STejun Heo return !cpumask_equal(cpumask, attrs->cpumask); 38374c16bd32STejun Heo 38384c16bd32STejun Heo use_dfl: 38394c16bd32STejun Heo cpumask_copy(cpumask, attrs->cpumask); 38404c16bd32STejun Heo return false; 38414c16bd32STejun Heo } 38424c16bd32STejun Heo 38431befcf30STejun Heo /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ 38441befcf30STejun Heo static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, 38451befcf30STejun Heo int node, 38461befcf30STejun Heo struct pool_workqueue *pwq) 38471befcf30STejun Heo { 38481befcf30STejun Heo struct pool_workqueue *old_pwq; 38491befcf30STejun Heo 38505b95e1afSLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 38511befcf30STejun Heo lockdep_assert_held(&wq->mutex); 38521befcf30STejun Heo 38531befcf30STejun Heo /* link_pwq() can handle duplicate calls */ 38541befcf30STejun Heo link_pwq(pwq); 38551befcf30STejun Heo 38561befcf30STejun Heo old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); 38571befcf30STejun Heo rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); 38581befcf30STejun Heo return old_pwq; 38591befcf30STejun Heo } 38601befcf30STejun Heo 38612d5f0764SLai Jiangshan /* context to store the prepared attrs & pwqs before applying */ 38622d5f0764SLai Jiangshan struct apply_wqattrs_ctx { 38632d5f0764SLai Jiangshan struct workqueue_struct *wq; /* target workqueue */ 38642d5f0764SLai Jiangshan struct workqueue_attrs *attrs; /* attrs to apply */ 3865042f7df1SLai Jiangshan struct list_head list; /* queued for batching commit */ 38662d5f0764SLai Jiangshan struct pool_workqueue *dfl_pwq; 38672d5f0764SLai Jiangshan struct pool_workqueue *pwq_tbl[]; 38682d5f0764SLai Jiangshan }; 38692d5f0764SLai Jiangshan 38702d5f0764SLai Jiangshan /* free the resources after success or abort */ 38712d5f0764SLai Jiangshan static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx) 38722d5f0764SLai Jiangshan { 38732d5f0764SLai Jiangshan if (ctx) { 38742d5f0764SLai Jiangshan int node; 38752d5f0764SLai Jiangshan 38762d5f0764SLai Jiangshan for_each_node(node) 38772d5f0764SLai Jiangshan put_pwq_unlocked(ctx->pwq_tbl[node]); 38782d5f0764SLai Jiangshan put_pwq_unlocked(ctx->dfl_pwq); 38792d5f0764SLai Jiangshan 38802d5f0764SLai Jiangshan free_workqueue_attrs(ctx->attrs); 38812d5f0764SLai Jiangshan 38822d5f0764SLai Jiangshan kfree(ctx); 38832d5f0764SLai Jiangshan } 38842d5f0764SLai Jiangshan } 38852d5f0764SLai Jiangshan 38862d5f0764SLai Jiangshan /* allocate the attrs and pwqs for later installation */ 38872d5f0764SLai Jiangshan static struct apply_wqattrs_ctx * 38882d5f0764SLai Jiangshan apply_wqattrs_prepare(struct workqueue_struct *wq, 38892d5f0764SLai Jiangshan const struct workqueue_attrs *attrs) 38902d5f0764SLai Jiangshan { 38912d5f0764SLai Jiangshan struct apply_wqattrs_ctx *ctx; 38922d5f0764SLai Jiangshan struct workqueue_attrs *new_attrs, *tmp_attrs; 38932d5f0764SLai Jiangshan int node; 38942d5f0764SLai Jiangshan 38952d5f0764SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 38962d5f0764SLai Jiangshan 3897acafe7e3SKees Cook ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_node_ids), GFP_KERNEL); 38982d5f0764SLai Jiangshan 3899be69d00dSThomas Gleixner new_attrs = alloc_workqueue_attrs(); 3900be69d00dSThomas Gleixner tmp_attrs = alloc_workqueue_attrs(); 39012d5f0764SLai Jiangshan if (!ctx || !new_attrs || !tmp_attrs) 39022d5f0764SLai Jiangshan goto out_free; 39032d5f0764SLai Jiangshan 3904042f7df1SLai Jiangshan /* 3905042f7df1SLai Jiangshan * Calculate the attrs of the default pwq. 3906042f7df1SLai Jiangshan * If the user configured cpumask doesn't overlap with the 3907042f7df1SLai Jiangshan * wq_unbound_cpumask, we fallback to the wq_unbound_cpumask. 3908042f7df1SLai Jiangshan */ 39092d5f0764SLai Jiangshan copy_workqueue_attrs(new_attrs, attrs); 3910b05a7928SFrederic Weisbecker cpumask_and(new_attrs->cpumask, new_attrs->cpumask, wq_unbound_cpumask); 3911042f7df1SLai Jiangshan if (unlikely(cpumask_empty(new_attrs->cpumask))) 3912042f7df1SLai Jiangshan cpumask_copy(new_attrs->cpumask, wq_unbound_cpumask); 39132d5f0764SLai Jiangshan 39142d5f0764SLai Jiangshan /* 39152d5f0764SLai Jiangshan * We may create multiple pwqs with differing cpumasks. Make a 39162d5f0764SLai Jiangshan * copy of @new_attrs which will be modified and used to obtain 39172d5f0764SLai Jiangshan * pools. 39182d5f0764SLai Jiangshan */ 39192d5f0764SLai Jiangshan copy_workqueue_attrs(tmp_attrs, new_attrs); 39202d5f0764SLai Jiangshan 39212d5f0764SLai Jiangshan /* 39222d5f0764SLai Jiangshan * If something goes wrong during CPU up/down, we'll fall back to 39232d5f0764SLai Jiangshan * the default pwq covering whole @attrs->cpumask. Always create 39242d5f0764SLai Jiangshan * it even if we don't use it immediately. 39252d5f0764SLai Jiangshan */ 39262d5f0764SLai Jiangshan ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs); 39272d5f0764SLai Jiangshan if (!ctx->dfl_pwq) 39282d5f0764SLai Jiangshan goto out_free; 39292d5f0764SLai Jiangshan 39302d5f0764SLai Jiangshan for_each_node(node) { 3931042f7df1SLai Jiangshan if (wq_calc_node_cpumask(new_attrs, node, -1, tmp_attrs->cpumask)) { 39322d5f0764SLai Jiangshan ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); 39332d5f0764SLai Jiangshan if (!ctx->pwq_tbl[node]) 39342d5f0764SLai Jiangshan goto out_free; 39352d5f0764SLai Jiangshan } else { 39362d5f0764SLai Jiangshan ctx->dfl_pwq->refcnt++; 39372d5f0764SLai Jiangshan ctx->pwq_tbl[node] = ctx->dfl_pwq; 39382d5f0764SLai Jiangshan } 39392d5f0764SLai Jiangshan } 39402d5f0764SLai Jiangshan 3941042f7df1SLai Jiangshan /* save the user configured attrs and sanitize it. */ 3942042f7df1SLai Jiangshan copy_workqueue_attrs(new_attrs, attrs); 3943042f7df1SLai Jiangshan cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); 39442d5f0764SLai Jiangshan ctx->attrs = new_attrs; 3945042f7df1SLai Jiangshan 39462d5f0764SLai Jiangshan ctx->wq = wq; 39472d5f0764SLai Jiangshan free_workqueue_attrs(tmp_attrs); 39482d5f0764SLai Jiangshan return ctx; 39492d5f0764SLai Jiangshan 39502d5f0764SLai Jiangshan out_free: 39512d5f0764SLai Jiangshan free_workqueue_attrs(tmp_attrs); 39522d5f0764SLai Jiangshan free_workqueue_attrs(new_attrs); 39532d5f0764SLai Jiangshan apply_wqattrs_cleanup(ctx); 39542d5f0764SLai Jiangshan return NULL; 39552d5f0764SLai Jiangshan } 39562d5f0764SLai Jiangshan 39572d5f0764SLai Jiangshan /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */ 39582d5f0764SLai Jiangshan static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx) 39592d5f0764SLai Jiangshan { 39602d5f0764SLai Jiangshan int node; 39612d5f0764SLai Jiangshan 39622d5f0764SLai Jiangshan /* all pwqs have been created successfully, let's install'em */ 39632d5f0764SLai Jiangshan mutex_lock(&ctx->wq->mutex); 39642d5f0764SLai Jiangshan 39652d5f0764SLai Jiangshan copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs); 39662d5f0764SLai Jiangshan 39672d5f0764SLai Jiangshan /* save the previous pwq and install the new one */ 39682d5f0764SLai Jiangshan for_each_node(node) 39692d5f0764SLai Jiangshan ctx->pwq_tbl[node] = numa_pwq_tbl_install(ctx->wq, node, 39702d5f0764SLai Jiangshan ctx->pwq_tbl[node]); 39712d5f0764SLai Jiangshan 39722d5f0764SLai Jiangshan /* @dfl_pwq might not have been used, ensure it's linked */ 39732d5f0764SLai Jiangshan link_pwq(ctx->dfl_pwq); 39742d5f0764SLai Jiangshan swap(ctx->wq->dfl_pwq, ctx->dfl_pwq); 39752d5f0764SLai Jiangshan 39762d5f0764SLai Jiangshan mutex_unlock(&ctx->wq->mutex); 39772d5f0764SLai Jiangshan } 39782d5f0764SLai Jiangshan 3979a0111cf6SLai Jiangshan static void apply_wqattrs_lock(void) 3980a0111cf6SLai Jiangshan { 3981a0111cf6SLai Jiangshan /* CPUs should stay stable across pwq creations and installations */ 3982a0111cf6SLai Jiangshan get_online_cpus(); 3983a0111cf6SLai Jiangshan mutex_lock(&wq_pool_mutex); 3984a0111cf6SLai Jiangshan } 3985a0111cf6SLai Jiangshan 3986a0111cf6SLai Jiangshan static void apply_wqattrs_unlock(void) 3987a0111cf6SLai Jiangshan { 3988a0111cf6SLai Jiangshan mutex_unlock(&wq_pool_mutex); 3989a0111cf6SLai Jiangshan put_online_cpus(); 3990a0111cf6SLai Jiangshan } 3991a0111cf6SLai Jiangshan 3992a0111cf6SLai Jiangshan static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, 3993a0111cf6SLai Jiangshan const struct workqueue_attrs *attrs) 3994a0111cf6SLai Jiangshan { 3995a0111cf6SLai Jiangshan struct apply_wqattrs_ctx *ctx; 3996a0111cf6SLai Jiangshan 3997a0111cf6SLai Jiangshan /* only unbound workqueues can change attributes */ 3998a0111cf6SLai Jiangshan if (WARN_ON(!(wq->flags & WQ_UNBOUND))) 3999a0111cf6SLai Jiangshan return -EINVAL; 4000a0111cf6SLai Jiangshan 4001a0111cf6SLai Jiangshan /* creating multiple pwqs breaks ordering guarantee */ 40020a94efb5STejun Heo if (!list_empty(&wq->pwqs)) { 40030a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 4004a0111cf6SLai Jiangshan return -EINVAL; 4005a0111cf6SLai Jiangshan 40060a94efb5STejun Heo wq->flags &= ~__WQ_ORDERED; 40070a94efb5STejun Heo } 40080a94efb5STejun Heo 4009a0111cf6SLai Jiangshan ctx = apply_wqattrs_prepare(wq, attrs); 40106201171eSwanghaibin if (!ctx) 40116201171eSwanghaibin return -ENOMEM; 4012a0111cf6SLai Jiangshan 4013a0111cf6SLai Jiangshan /* the ctx has been prepared successfully, let's commit it */ 4014a0111cf6SLai Jiangshan apply_wqattrs_commit(ctx); 4015a0111cf6SLai Jiangshan apply_wqattrs_cleanup(ctx); 4016a0111cf6SLai Jiangshan 40176201171eSwanghaibin return 0; 4018a0111cf6SLai Jiangshan } 4019a0111cf6SLai Jiangshan 40209e8cd2f5STejun Heo /** 40219e8cd2f5STejun Heo * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue 40229e8cd2f5STejun Heo * @wq: the target workqueue 40239e8cd2f5STejun Heo * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() 40249e8cd2f5STejun Heo * 40254c16bd32STejun Heo * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA 40264c16bd32STejun Heo * machines, this function maps a separate pwq to each NUMA node with 40274c16bd32STejun Heo * possibles CPUs in @attrs->cpumask so that work items are affine to the 40284c16bd32STejun Heo * NUMA node it was issued on. Older pwqs are released as in-flight work 40294c16bd32STejun Heo * items finish. Note that a work item which repeatedly requeues itself 40304c16bd32STejun Heo * back-to-back will stay on its current pwq. 40319e8cd2f5STejun Heo * 4032d185af30SYacine Belkadi * Performs GFP_KERNEL allocations. 4033d185af30SYacine Belkadi * 4034509b3204SDaniel Jordan * Assumes caller has CPU hotplug read exclusion, i.e. get_online_cpus(). 4035509b3204SDaniel Jordan * 4036d185af30SYacine Belkadi * Return: 0 on success and -errno on failure. 40379e8cd2f5STejun Heo */ 4038513c98d0SDaniel Jordan int apply_workqueue_attrs(struct workqueue_struct *wq, 40399e8cd2f5STejun Heo const struct workqueue_attrs *attrs) 40409e8cd2f5STejun Heo { 4041a0111cf6SLai Jiangshan int ret; 40429e8cd2f5STejun Heo 4043509b3204SDaniel Jordan lockdep_assert_cpus_held(); 4044509b3204SDaniel Jordan 4045509b3204SDaniel Jordan mutex_lock(&wq_pool_mutex); 4046a0111cf6SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 4047509b3204SDaniel Jordan mutex_unlock(&wq_pool_mutex); 40482d5f0764SLai Jiangshan 40492d5f0764SLai Jiangshan return ret; 40509e8cd2f5STejun Heo } 40519e8cd2f5STejun Heo 40524c16bd32STejun Heo /** 40534c16bd32STejun Heo * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug 40544c16bd32STejun Heo * @wq: the target workqueue 40554c16bd32STejun Heo * @cpu: the CPU coming up or going down 40564c16bd32STejun Heo * @online: whether @cpu is coming up or going down 40574c16bd32STejun Heo * 40584c16bd32STejun Heo * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and 40594c16bd32STejun Heo * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of 40604c16bd32STejun Heo * @wq accordingly. 40614c16bd32STejun Heo * 40624c16bd32STejun Heo * If NUMA affinity can't be adjusted due to memory allocation failure, it 40634c16bd32STejun Heo * falls back to @wq->dfl_pwq which may not be optimal but is always 40644c16bd32STejun Heo * correct. 40654c16bd32STejun Heo * 40664c16bd32STejun Heo * Note that when the last allowed CPU of a NUMA node goes offline for a 40674c16bd32STejun Heo * workqueue with a cpumask spanning multiple nodes, the workers which were 40684c16bd32STejun Heo * already executing the work items for the workqueue will lose their CPU 40694c16bd32STejun Heo * affinity and may execute on any CPU. This is similar to how per-cpu 40704c16bd32STejun Heo * workqueues behave on CPU_DOWN. If a workqueue user wants strict 40714c16bd32STejun Heo * affinity, it's the user's responsibility to flush the work item from 40724c16bd32STejun Heo * CPU_DOWN_PREPARE. 40734c16bd32STejun Heo */ 40744c16bd32STejun Heo static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, 40754c16bd32STejun Heo bool online) 40764c16bd32STejun Heo { 40774c16bd32STejun Heo int node = cpu_to_node(cpu); 40784c16bd32STejun Heo int cpu_off = online ? -1 : cpu; 40794c16bd32STejun Heo struct pool_workqueue *old_pwq = NULL, *pwq; 40804c16bd32STejun Heo struct workqueue_attrs *target_attrs; 40814c16bd32STejun Heo cpumask_t *cpumask; 40824c16bd32STejun Heo 40834c16bd32STejun Heo lockdep_assert_held(&wq_pool_mutex); 40844c16bd32STejun Heo 4085f7142ed4SLai Jiangshan if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND) || 4086f7142ed4SLai Jiangshan wq->unbound_attrs->no_numa) 40874c16bd32STejun Heo return; 40884c16bd32STejun Heo 40894c16bd32STejun Heo /* 40904c16bd32STejun Heo * We don't wanna alloc/free wq_attrs for each wq for each CPU. 40914c16bd32STejun Heo * Let's use a preallocated one. The following buf is protected by 40924c16bd32STejun Heo * CPU hotplug exclusion. 40934c16bd32STejun Heo */ 40944c16bd32STejun Heo target_attrs = wq_update_unbound_numa_attrs_buf; 40954c16bd32STejun Heo cpumask = target_attrs->cpumask; 40964c16bd32STejun Heo 40974c16bd32STejun Heo copy_workqueue_attrs(target_attrs, wq->unbound_attrs); 40984c16bd32STejun Heo pwq = unbound_pwq_by_node(wq, node); 40994c16bd32STejun Heo 41004c16bd32STejun Heo /* 41014c16bd32STejun Heo * Let's determine what needs to be done. If the target cpumask is 4102042f7df1SLai Jiangshan * different from the default pwq's, we need to compare it to @pwq's 4103042f7df1SLai Jiangshan * and create a new one if they don't match. If the target cpumask 4104042f7df1SLai Jiangshan * equals the default pwq's, the default pwq should be used. 41054c16bd32STejun Heo */ 4106042f7df1SLai Jiangshan if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) { 41074c16bd32STejun Heo if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) 4108f7142ed4SLai Jiangshan return; 41094c16bd32STejun Heo } else { 41104c16bd32STejun Heo goto use_dfl_pwq; 41114c16bd32STejun Heo } 41124c16bd32STejun Heo 41134c16bd32STejun Heo /* create a new pwq */ 41144c16bd32STejun Heo pwq = alloc_unbound_pwq(wq, target_attrs); 41154c16bd32STejun Heo if (!pwq) { 41162d916033SFabian Frederick pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", 41174c16bd32STejun Heo wq->name); 411877f300b1SDaeseok Youn goto use_dfl_pwq; 41194c16bd32STejun Heo } 41204c16bd32STejun Heo 4121f7142ed4SLai Jiangshan /* Install the new pwq. */ 41224c16bd32STejun Heo mutex_lock(&wq->mutex); 41234c16bd32STejun Heo old_pwq = numa_pwq_tbl_install(wq, node, pwq); 41244c16bd32STejun Heo goto out_unlock; 41254c16bd32STejun Heo 41264c16bd32STejun Heo use_dfl_pwq: 4127f7142ed4SLai Jiangshan mutex_lock(&wq->mutex); 41284c16bd32STejun Heo spin_lock_irq(&wq->dfl_pwq->pool->lock); 41294c16bd32STejun Heo get_pwq(wq->dfl_pwq); 41304c16bd32STejun Heo spin_unlock_irq(&wq->dfl_pwq->pool->lock); 41314c16bd32STejun Heo old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); 41324c16bd32STejun Heo out_unlock: 41334c16bd32STejun Heo mutex_unlock(&wq->mutex); 41344c16bd32STejun Heo put_pwq_unlocked(old_pwq); 41354c16bd32STejun Heo } 41364c16bd32STejun Heo 413730cdf249STejun Heo static int alloc_and_link_pwqs(struct workqueue_struct *wq) 41381da177e4SLinus Torvalds { 413949e3cf44STejun Heo bool highpri = wq->flags & WQ_HIGHPRI; 41408a2b7538STejun Heo int cpu, ret; 4141e1d8aa9fSFrederic Weisbecker 414230cdf249STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 4143420c0ddbSTejun Heo wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); 4144420c0ddbSTejun Heo if (!wq->cpu_pwqs) 414530cdf249STejun Heo return -ENOMEM; 414630cdf249STejun Heo 414730cdf249STejun Heo for_each_possible_cpu(cpu) { 41487fb98ea7STejun Heo struct pool_workqueue *pwq = 41497fb98ea7STejun Heo per_cpu_ptr(wq->cpu_pwqs, cpu); 41507a62c2c8STejun Heo struct worker_pool *cpu_pools = 4151f02ae73aSTejun Heo per_cpu(cpu_worker_pools, cpu); 415230cdf249STejun Heo 4153f147f29eSTejun Heo init_pwq(pwq, wq, &cpu_pools[highpri]); 4154f147f29eSTejun Heo 4155f147f29eSTejun Heo mutex_lock(&wq->mutex); 41561befcf30STejun Heo link_pwq(pwq); 4157f147f29eSTejun Heo mutex_unlock(&wq->mutex); 415830cdf249STejun Heo } 415930cdf249STejun Heo return 0; 4160509b3204SDaniel Jordan } 4161509b3204SDaniel Jordan 4162509b3204SDaniel Jordan get_online_cpus(); 4163509b3204SDaniel Jordan if (wq->flags & __WQ_ORDERED) { 41648a2b7538STejun Heo ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); 41658a2b7538STejun Heo /* there should only be single pwq for ordering guarantee */ 41668a2b7538STejun Heo WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || 41678a2b7538STejun Heo wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), 41688a2b7538STejun Heo "ordering guarantee broken for workqueue %s\n", wq->name); 41699e8cd2f5STejun Heo } else { 4170509b3204SDaniel Jordan ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); 41719e8cd2f5STejun Heo } 4172509b3204SDaniel Jordan put_online_cpus(); 4173509b3204SDaniel Jordan 4174509b3204SDaniel Jordan return ret; 41750f900049STejun Heo } 41760f900049STejun Heo 4177f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 4178f3421797STejun Heo const char *name) 4179b71ab8c2STejun Heo { 4180f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 4181f3421797STejun Heo 4182f3421797STejun Heo if (max_active < 1 || max_active > lim) 4183044c782cSValentin Ilie pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 4184f3421797STejun Heo max_active, name, 1, lim); 4185b71ab8c2STejun Heo 4186f3421797STejun Heo return clamp_val(max_active, 1, lim); 4187b71ab8c2STejun Heo } 4188b71ab8c2STejun Heo 4189983c7515STejun Heo /* 4190983c7515STejun Heo * Workqueues which may be used during memory reclaim should have a rescuer 4191983c7515STejun Heo * to guarantee forward progress. 4192983c7515STejun Heo */ 4193983c7515STejun Heo static int init_rescuer(struct workqueue_struct *wq) 4194983c7515STejun Heo { 4195983c7515STejun Heo struct worker *rescuer; 4196983c7515STejun Heo int ret; 4197983c7515STejun Heo 4198983c7515STejun Heo if (!(wq->flags & WQ_MEM_RECLAIM)) 4199983c7515STejun Heo return 0; 4200983c7515STejun Heo 4201983c7515STejun Heo rescuer = alloc_worker(NUMA_NO_NODE); 4202983c7515STejun Heo if (!rescuer) 4203983c7515STejun Heo return -ENOMEM; 4204983c7515STejun Heo 4205983c7515STejun Heo rescuer->rescue_wq = wq; 4206983c7515STejun Heo rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name); 4207983c7515STejun Heo ret = PTR_ERR_OR_ZERO(rescuer->task); 4208983c7515STejun Heo if (ret) { 4209983c7515STejun Heo kfree(rescuer); 4210983c7515STejun Heo return ret; 4211983c7515STejun Heo } 4212983c7515STejun Heo 4213983c7515STejun Heo wq->rescuer = rescuer; 4214983c7515STejun Heo kthread_bind_mask(rescuer->task, cpu_possible_mask); 4215983c7515STejun Heo wake_up_process(rescuer->task); 4216983c7515STejun Heo 4217983c7515STejun Heo return 0; 4218983c7515STejun Heo } 4219983c7515STejun Heo 4220a2775bbcSMathieu Malaterre __printf(1, 4) 4221669de8bdSBart Van Assche struct workqueue_struct *alloc_workqueue(const char *fmt, 422297e37d7bSTejun Heo unsigned int flags, 4223669de8bdSBart Van Assche int max_active, ...) 42243af24433SOleg Nesterov { 4225df2d5ae4STejun Heo size_t tbl_size = 0; 4226ecf6881fSTejun Heo va_list args; 42273af24433SOleg Nesterov struct workqueue_struct *wq; 422849e3cf44STejun Heo struct pool_workqueue *pwq; 4229b196be89STejun Heo 42305c0338c6STejun Heo /* 42315c0338c6STejun Heo * Unbound && max_active == 1 used to imply ordered, which is no 42325c0338c6STejun Heo * longer the case on NUMA machines due to per-node pools. While 42335c0338c6STejun Heo * alloc_ordered_workqueue() is the right way to create an ordered 42345c0338c6STejun Heo * workqueue, keep the previous behavior to avoid subtle breakages 42355c0338c6STejun Heo * on NUMA. 42365c0338c6STejun Heo */ 42375c0338c6STejun Heo if ((flags & WQ_UNBOUND) && max_active == 1) 42385c0338c6STejun Heo flags |= __WQ_ORDERED; 42395c0338c6STejun Heo 4240cee22a15SViresh Kumar /* see the comment above the definition of WQ_POWER_EFFICIENT */ 4241cee22a15SViresh Kumar if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) 4242cee22a15SViresh Kumar flags |= WQ_UNBOUND; 4243cee22a15SViresh Kumar 4244ecf6881fSTejun Heo /* allocate wq and format name */ 4245df2d5ae4STejun Heo if (flags & WQ_UNBOUND) 4246ddcb57e2SLai Jiangshan tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]); 4247df2d5ae4STejun Heo 4248df2d5ae4STejun Heo wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); 4249b196be89STejun Heo if (!wq) 4250d2c1d404STejun Heo return NULL; 4251b196be89STejun Heo 42526029a918STejun Heo if (flags & WQ_UNBOUND) { 4253be69d00dSThomas Gleixner wq->unbound_attrs = alloc_workqueue_attrs(); 42546029a918STejun Heo if (!wq->unbound_attrs) 42556029a918STejun Heo goto err_free_wq; 42566029a918STejun Heo } 42576029a918STejun Heo 4258669de8bdSBart Van Assche va_start(args, max_active); 4259ecf6881fSTejun Heo vsnprintf(wq->name, sizeof(wq->name), fmt, args); 4260b196be89STejun Heo va_end(args); 42613af24433SOleg Nesterov 4262d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 4263b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 42643af24433SOleg Nesterov 4265b196be89STejun Heo /* init wq */ 426697e37d7bSTejun Heo wq->flags = flags; 4267a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 42683c25a55dSLai Jiangshan mutex_init(&wq->mutex); 4269112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 0); 427030cdf249STejun Heo INIT_LIST_HEAD(&wq->pwqs); 427173f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 427273f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 4273493a1724STejun Heo INIT_LIST_HEAD(&wq->maydays); 42743af24433SOleg Nesterov 4275669de8bdSBart Van Assche wq_init_lockdep(wq); 4276cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 42773af24433SOleg Nesterov 427830cdf249STejun Heo if (alloc_and_link_pwqs(wq) < 0) 427982efcab3SBart Van Assche goto err_unreg_lockdep; 42801537663fSTejun Heo 428140c17f75STejun Heo if (wq_online && init_rescuer(wq) < 0) 4282d2c1d404STejun Heo goto err_destroy; 4283e22bee78STejun Heo 4284226223abSTejun Heo if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) 4285226223abSTejun Heo goto err_destroy; 4286226223abSTejun Heo 42876af8bf3dSOleg Nesterov /* 428868e13a67SLai Jiangshan * wq_pool_mutex protects global freeze state and workqueues list. 428968e13a67SLai Jiangshan * Grab it, adjust max_active and add the new @wq to workqueues 429068e13a67SLai Jiangshan * list. 42916af8bf3dSOleg Nesterov */ 429268e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4293a0a1a5fdSTejun Heo 4294a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 429549e3cf44STejun Heo for_each_pwq(pwq, wq) 4296699ce097STejun Heo pwq_adjust_max_active(pwq); 4297a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4298a0a1a5fdSTejun Heo 4299e2dca7adSTejun Heo list_add_tail_rcu(&wq->list, &workqueues); 4300a0a1a5fdSTejun Heo 430168e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 43023af24433SOleg Nesterov 43033af24433SOleg Nesterov return wq; 4304d2c1d404STejun Heo 430582efcab3SBart Van Assche err_unreg_lockdep: 4306009bb421SBart Van Assche wq_unregister_lockdep(wq); 4307009bb421SBart Van Assche wq_free_lockdep(wq); 430882efcab3SBart Van Assche err_free_wq: 43096029a918STejun Heo free_workqueue_attrs(wq->unbound_attrs); 43104690c4abSTejun Heo kfree(wq); 4311d2c1d404STejun Heo return NULL; 4312d2c1d404STejun Heo err_destroy: 4313d2c1d404STejun Heo destroy_workqueue(wq); 43144690c4abSTejun Heo return NULL; 43151da177e4SLinus Torvalds } 4316669de8bdSBart Van Assche EXPORT_SYMBOL_GPL(alloc_workqueue); 43171da177e4SLinus Torvalds 4318c29eb853STejun Heo static bool pwq_busy(struct pool_workqueue *pwq) 4319c29eb853STejun Heo { 4320c29eb853STejun Heo int i; 4321c29eb853STejun Heo 4322c29eb853STejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 4323c29eb853STejun Heo if (pwq->nr_in_flight[i]) 4324c29eb853STejun Heo return true; 4325c29eb853STejun Heo 4326c29eb853STejun Heo if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1)) 4327c29eb853STejun Heo return true; 4328c29eb853STejun Heo if (pwq->nr_active || !list_empty(&pwq->delayed_works)) 4329c29eb853STejun Heo return true; 4330c29eb853STejun Heo 4331c29eb853STejun Heo return false; 4332c29eb853STejun Heo } 4333c29eb853STejun Heo 43343af24433SOleg Nesterov /** 43353af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 43363af24433SOleg Nesterov * @wq: target workqueue 43373af24433SOleg Nesterov * 43383af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 43393af24433SOleg Nesterov */ 43403af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 43413af24433SOleg Nesterov { 434249e3cf44STejun Heo struct pool_workqueue *pwq; 43434c16bd32STejun Heo int node; 43443af24433SOleg Nesterov 4345def98c84STejun Heo /* 4346def98c84STejun Heo * Remove it from sysfs first so that sanity check failure doesn't 4347def98c84STejun Heo * lead to sysfs name conflicts. 4348def98c84STejun Heo */ 4349def98c84STejun Heo workqueue_sysfs_unregister(wq); 4350def98c84STejun Heo 43519c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 43529c5a2ba7STejun Heo drain_workqueue(wq); 4353c8efcc25STejun Heo 4354def98c84STejun Heo /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ 4355def98c84STejun Heo if (wq->rescuer) { 4356def98c84STejun Heo struct worker *rescuer = wq->rescuer; 4357def98c84STejun Heo 4358def98c84STejun Heo /* this prevents new queueing */ 4359def98c84STejun Heo spin_lock_irq(&wq_mayday_lock); 4360def98c84STejun Heo wq->rescuer = NULL; 4361def98c84STejun Heo spin_unlock_irq(&wq_mayday_lock); 4362def98c84STejun Heo 4363def98c84STejun Heo /* rescuer will empty maydays list before exiting */ 4364def98c84STejun Heo kthread_stop(rescuer->task); 43658efe1223STejun Heo kfree(rescuer); 4366def98c84STejun Heo } 4367def98c84STejun Heo 4368c29eb853STejun Heo /* 4369c29eb853STejun Heo * Sanity checks - grab all the locks so that we wait for all 4370c29eb853STejun Heo * in-flight operations which may do put_pwq(). 4371c29eb853STejun Heo */ 4372c29eb853STejun Heo mutex_lock(&wq_pool_mutex); 4373b09f4fd3SLai Jiangshan mutex_lock(&wq->mutex); 437449e3cf44STejun Heo for_each_pwq(pwq, wq) { 4375c29eb853STejun Heo spin_lock_irq(&pwq->pool->lock); 4376c29eb853STejun Heo if (WARN_ON(pwq_busy(pwq))) { 4377c29eb853STejun Heo pr_warning("%s: %s has the following busy pwq (refcnt=%d)\n", 4378c29eb853STejun Heo __func__, wq->name, pwq->refcnt); 4379c29eb853STejun Heo show_pwq(pwq); 4380c29eb853STejun Heo spin_unlock_irq(&pwq->pool->lock); 4381b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 4382c29eb853STejun Heo mutex_unlock(&wq_pool_mutex); 4383fa07fb6aSTejun Heo show_workqueue_state(); 43846183c009STejun Heo return; 438576af4d93STejun Heo } 4386c29eb853STejun Heo spin_unlock_irq(&pwq->pool->lock); 438776af4d93STejun Heo } 4388b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 4389c29eb853STejun Heo mutex_unlock(&wq_pool_mutex); 43906183c009STejun Heo 4391a0a1a5fdSTejun Heo /* 4392a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 4393a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 4394a0a1a5fdSTejun Heo */ 439568e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4396e2dca7adSTejun Heo list_del_rcu(&wq->list); 439768e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 43983af24433SOleg Nesterov 43998864b4e5STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 4400669de8bdSBart Van Assche wq_unregister_lockdep(wq); 440129c91e99STejun Heo /* 44028864b4e5STejun Heo * The base ref is never dropped on per-cpu pwqs. Directly 4403e2dca7adSTejun Heo * schedule RCU free. 440429c91e99STejun Heo */ 440525b00775SPaul E. McKenney call_rcu(&wq->rcu, rcu_free_wq); 44068864b4e5STejun Heo } else { 44078864b4e5STejun Heo /* 44088864b4e5STejun Heo * We're the sole accessor of @wq at this point. Directly 44094c16bd32STejun Heo * access numa_pwq_tbl[] and dfl_pwq to put the base refs. 44104c16bd32STejun Heo * @wq will be freed when the last pwq is released. 44118864b4e5STejun Heo */ 44124c16bd32STejun Heo for_each_node(node) { 44134c16bd32STejun Heo pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); 44144c16bd32STejun Heo RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); 44154c16bd32STejun Heo put_pwq_unlocked(pwq); 44164c16bd32STejun Heo } 44174c16bd32STejun Heo 44184c16bd32STejun Heo /* 44194c16bd32STejun Heo * Put dfl_pwq. @wq may be freed any time after dfl_pwq is 44204c16bd32STejun Heo * put. Don't access it afterwards. 44214c16bd32STejun Heo */ 44224c16bd32STejun Heo pwq = wq->dfl_pwq; 44234c16bd32STejun Heo wq->dfl_pwq = NULL; 4424dce90d47STejun Heo put_pwq_unlocked(pwq); 442529c91e99STejun Heo } 44263af24433SOleg Nesterov } 44273af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 44283af24433SOleg Nesterov 4429dcd989cbSTejun Heo /** 4430dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 4431dcd989cbSTejun Heo * @wq: target workqueue 4432dcd989cbSTejun Heo * @max_active: new max_active value. 4433dcd989cbSTejun Heo * 4434dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 4435dcd989cbSTejun Heo * 4436dcd989cbSTejun Heo * CONTEXT: 4437dcd989cbSTejun Heo * Don't call from IRQ context. 4438dcd989cbSTejun Heo */ 4439dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 4440dcd989cbSTejun Heo { 444149e3cf44STejun Heo struct pool_workqueue *pwq; 4442dcd989cbSTejun Heo 44438719dceaSTejun Heo /* disallow meddling with max_active for ordered workqueues */ 44440a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 44458719dceaSTejun Heo return; 44468719dceaSTejun Heo 4447f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 4448dcd989cbSTejun Heo 4449a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 4450dcd989cbSTejun Heo 44510a94efb5STejun Heo wq->flags &= ~__WQ_ORDERED; 4452dcd989cbSTejun Heo wq->saved_max_active = max_active; 4453dcd989cbSTejun Heo 4454699ce097STejun Heo for_each_pwq(pwq, wq) 4455699ce097STejun Heo pwq_adjust_max_active(pwq); 4456dcd989cbSTejun Heo 4457a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4458dcd989cbSTejun Heo } 4459dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 4460dcd989cbSTejun Heo 4461dcd989cbSTejun Heo /** 446227d4ee03SLukas Wunner * current_work - retrieve %current task's work struct 446327d4ee03SLukas Wunner * 446427d4ee03SLukas Wunner * Determine if %current task is a workqueue worker and what it's working on. 446527d4ee03SLukas Wunner * Useful to find out the context that the %current task is running in. 446627d4ee03SLukas Wunner * 446727d4ee03SLukas Wunner * Return: work struct if %current task is a workqueue worker, %NULL otherwise. 446827d4ee03SLukas Wunner */ 446927d4ee03SLukas Wunner struct work_struct *current_work(void) 447027d4ee03SLukas Wunner { 447127d4ee03SLukas Wunner struct worker *worker = current_wq_worker(); 447227d4ee03SLukas Wunner 447327d4ee03SLukas Wunner return worker ? worker->current_work : NULL; 447427d4ee03SLukas Wunner } 447527d4ee03SLukas Wunner EXPORT_SYMBOL(current_work); 447627d4ee03SLukas Wunner 447727d4ee03SLukas Wunner /** 4478e6267616STejun Heo * current_is_workqueue_rescuer - is %current workqueue rescuer? 4479e6267616STejun Heo * 4480e6267616STejun Heo * Determine whether %current is a workqueue rescuer. Can be used from 4481e6267616STejun Heo * work functions to determine whether it's being run off the rescuer task. 4482d185af30SYacine Belkadi * 4483d185af30SYacine Belkadi * Return: %true if %current is a workqueue rescuer. %false otherwise. 4484e6267616STejun Heo */ 4485e6267616STejun Heo bool current_is_workqueue_rescuer(void) 4486e6267616STejun Heo { 4487e6267616STejun Heo struct worker *worker = current_wq_worker(); 4488e6267616STejun Heo 44896a092dfdSLai Jiangshan return worker && worker->rescue_wq; 4490e6267616STejun Heo } 4491e6267616STejun Heo 4492e6267616STejun Heo /** 4493dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 4494dcd989cbSTejun Heo * @cpu: CPU in question 4495dcd989cbSTejun Heo * @wq: target workqueue 4496dcd989cbSTejun Heo * 4497dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 4498dcd989cbSTejun Heo * no synchronization around this function and the test result is 4499dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 4500dcd989cbSTejun Heo * 4501d3251859STejun Heo * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. 4502d3251859STejun Heo * Note that both per-cpu and unbound workqueues may be associated with 4503d3251859STejun Heo * multiple pool_workqueues which have separate congested states. A 4504d3251859STejun Heo * workqueue being congested on one CPU doesn't mean the workqueue is also 4505d3251859STejun Heo * contested on other CPUs / NUMA nodes. 4506d3251859STejun Heo * 4507d185af30SYacine Belkadi * Return: 4508dcd989cbSTejun Heo * %true if congested, %false otherwise. 4509dcd989cbSTejun Heo */ 4510d84ff051STejun Heo bool workqueue_congested(int cpu, struct workqueue_struct *wq) 4511dcd989cbSTejun Heo { 45127fb98ea7STejun Heo struct pool_workqueue *pwq; 451376af4d93STejun Heo bool ret; 451476af4d93STejun Heo 451524acfb71SThomas Gleixner rcu_read_lock(); 451624acfb71SThomas Gleixner preempt_disable(); 45177fb98ea7STejun Heo 4518d3251859STejun Heo if (cpu == WORK_CPU_UNBOUND) 4519d3251859STejun Heo cpu = smp_processor_id(); 4520d3251859STejun Heo 45217fb98ea7STejun Heo if (!(wq->flags & WQ_UNBOUND)) 45227fb98ea7STejun Heo pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); 45237fb98ea7STejun Heo else 4524df2d5ae4STejun Heo pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); 4525dcd989cbSTejun Heo 452676af4d93STejun Heo ret = !list_empty(&pwq->delayed_works); 452724acfb71SThomas Gleixner preempt_enable(); 452824acfb71SThomas Gleixner rcu_read_unlock(); 452976af4d93STejun Heo 453076af4d93STejun Heo return ret; 4531dcd989cbSTejun Heo } 4532dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 4533dcd989cbSTejun Heo 4534dcd989cbSTejun Heo /** 4535dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 4536dcd989cbSTejun Heo * @work: the work to be tested 4537dcd989cbSTejun Heo * 4538dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 4539dcd989cbSTejun Heo * synchronization around this function and the test result is 4540dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 4541dcd989cbSTejun Heo * 4542d185af30SYacine Belkadi * Return: 4543dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 4544dcd989cbSTejun Heo */ 4545dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 4546dcd989cbSTejun Heo { 4547fa1b54e6STejun Heo struct worker_pool *pool; 4548dcd989cbSTejun Heo unsigned long flags; 4549dcd989cbSTejun Heo unsigned int ret = 0; 4550dcd989cbSTejun Heo 4551dcd989cbSTejun Heo if (work_pending(work)) 4552dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 4553038366c5SLai Jiangshan 455424acfb71SThomas Gleixner rcu_read_lock(); 4555fa1b54e6STejun Heo pool = get_work_pool(work); 4556038366c5SLai Jiangshan if (pool) { 455724acfb71SThomas Gleixner spin_lock_irqsave(&pool->lock, flags); 4558c9e7cf27STejun Heo if (find_worker_executing_work(pool, work)) 4559dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 456024acfb71SThomas Gleixner spin_unlock_irqrestore(&pool->lock, flags); 4561038366c5SLai Jiangshan } 456224acfb71SThomas Gleixner rcu_read_unlock(); 4563dcd989cbSTejun Heo 4564dcd989cbSTejun Heo return ret; 4565dcd989cbSTejun Heo } 4566dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 4567dcd989cbSTejun Heo 45683d1cb205STejun Heo /** 45693d1cb205STejun Heo * set_worker_desc - set description for the current work item 45703d1cb205STejun Heo * @fmt: printf-style format string 45713d1cb205STejun Heo * @...: arguments for the format string 45723d1cb205STejun Heo * 45733d1cb205STejun Heo * This function can be called by a running work function to describe what 45743d1cb205STejun Heo * the work item is about. If the worker task gets dumped, this 45753d1cb205STejun Heo * information will be printed out together to help debugging. The 45763d1cb205STejun Heo * description can be at most WORKER_DESC_LEN including the trailing '\0'. 45773d1cb205STejun Heo */ 45783d1cb205STejun Heo void set_worker_desc(const char *fmt, ...) 45793d1cb205STejun Heo { 45803d1cb205STejun Heo struct worker *worker = current_wq_worker(); 45813d1cb205STejun Heo va_list args; 45823d1cb205STejun Heo 45833d1cb205STejun Heo if (worker) { 45843d1cb205STejun Heo va_start(args, fmt); 45853d1cb205STejun Heo vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); 45863d1cb205STejun Heo va_end(args); 45873d1cb205STejun Heo } 45883d1cb205STejun Heo } 45895c750d58SSteffen Maier EXPORT_SYMBOL_GPL(set_worker_desc); 45903d1cb205STejun Heo 45913d1cb205STejun Heo /** 45923d1cb205STejun Heo * print_worker_info - print out worker information and description 45933d1cb205STejun Heo * @log_lvl: the log level to use when printing 45943d1cb205STejun Heo * @task: target task 45953d1cb205STejun Heo * 45963d1cb205STejun Heo * If @task is a worker and currently executing a work item, print out the 45973d1cb205STejun Heo * name of the workqueue being serviced and worker description set with 45983d1cb205STejun Heo * set_worker_desc() by the currently executing work item. 45993d1cb205STejun Heo * 46003d1cb205STejun Heo * This function can be safely called on any task as long as the 46013d1cb205STejun Heo * task_struct itself is accessible. While safe, this function isn't 46023d1cb205STejun Heo * synchronized and may print out mixups or garbages of limited length. 46033d1cb205STejun Heo */ 46043d1cb205STejun Heo void print_worker_info(const char *log_lvl, struct task_struct *task) 46053d1cb205STejun Heo { 46063d1cb205STejun Heo work_func_t *fn = NULL; 46073d1cb205STejun Heo char name[WQ_NAME_LEN] = { }; 46083d1cb205STejun Heo char desc[WORKER_DESC_LEN] = { }; 46093d1cb205STejun Heo struct pool_workqueue *pwq = NULL; 46103d1cb205STejun Heo struct workqueue_struct *wq = NULL; 46113d1cb205STejun Heo struct worker *worker; 46123d1cb205STejun Heo 46133d1cb205STejun Heo if (!(task->flags & PF_WQ_WORKER)) 46143d1cb205STejun Heo return; 46153d1cb205STejun Heo 46163d1cb205STejun Heo /* 46173d1cb205STejun Heo * This function is called without any synchronization and @task 46183d1cb205STejun Heo * could be in any state. Be careful with dereferences. 46193d1cb205STejun Heo */ 4620e700591aSPetr Mladek worker = kthread_probe_data(task); 46213d1cb205STejun Heo 46223d1cb205STejun Heo /* 46238bf89593STejun Heo * Carefully copy the associated workqueue's workfn, name and desc. 46248bf89593STejun Heo * Keep the original last '\0' in case the original is garbage. 46253d1cb205STejun Heo */ 46263d1cb205STejun Heo probe_kernel_read(&fn, &worker->current_func, sizeof(fn)); 46273d1cb205STejun Heo probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); 46283d1cb205STejun Heo probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); 46293d1cb205STejun Heo probe_kernel_read(name, wq->name, sizeof(name) - 1); 46303d1cb205STejun Heo probe_kernel_read(desc, worker->desc, sizeof(desc) - 1); 46313d1cb205STejun Heo 46323d1cb205STejun Heo if (fn || name[0] || desc[0]) { 4633d75f773cSSakari Ailus printk("%sWorkqueue: %s %ps", log_lvl, name, fn); 46348bf89593STejun Heo if (strcmp(name, desc)) 46353d1cb205STejun Heo pr_cont(" (%s)", desc); 46363d1cb205STejun Heo pr_cont("\n"); 46373d1cb205STejun Heo } 46383d1cb205STejun Heo } 46393d1cb205STejun Heo 46403494fc30STejun Heo static void pr_cont_pool_info(struct worker_pool *pool) 46413494fc30STejun Heo { 46423494fc30STejun Heo pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask); 46433494fc30STejun Heo if (pool->node != NUMA_NO_NODE) 46443494fc30STejun Heo pr_cont(" node=%d", pool->node); 46453494fc30STejun Heo pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice); 46463494fc30STejun Heo } 46473494fc30STejun Heo 46483494fc30STejun Heo static void pr_cont_work(bool comma, struct work_struct *work) 46493494fc30STejun Heo { 46503494fc30STejun Heo if (work->func == wq_barrier_func) { 46513494fc30STejun Heo struct wq_barrier *barr; 46523494fc30STejun Heo 46533494fc30STejun Heo barr = container_of(work, struct wq_barrier, work); 46543494fc30STejun Heo 46553494fc30STejun Heo pr_cont("%s BAR(%d)", comma ? "," : "", 46563494fc30STejun Heo task_pid_nr(barr->task)); 46573494fc30STejun Heo } else { 4658d75f773cSSakari Ailus pr_cont("%s %ps", comma ? "," : "", work->func); 46593494fc30STejun Heo } 46603494fc30STejun Heo } 46613494fc30STejun Heo 46623494fc30STejun Heo static void show_pwq(struct pool_workqueue *pwq) 46633494fc30STejun Heo { 46643494fc30STejun Heo struct worker_pool *pool = pwq->pool; 46653494fc30STejun Heo struct work_struct *work; 46663494fc30STejun Heo struct worker *worker; 46673494fc30STejun Heo bool has_in_flight = false, has_pending = false; 46683494fc30STejun Heo int bkt; 46693494fc30STejun Heo 46703494fc30STejun Heo pr_info(" pwq %d:", pool->id); 46713494fc30STejun Heo pr_cont_pool_info(pool); 46723494fc30STejun Heo 46733494fc30STejun Heo pr_cont(" active=%d/%d%s\n", pwq->nr_active, pwq->max_active, 46743494fc30STejun Heo !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); 46753494fc30STejun Heo 46763494fc30STejun Heo hash_for_each(pool->busy_hash, bkt, worker, hentry) { 46773494fc30STejun Heo if (worker->current_pwq == pwq) { 46783494fc30STejun Heo has_in_flight = true; 46793494fc30STejun Heo break; 46803494fc30STejun Heo } 46813494fc30STejun Heo } 46823494fc30STejun Heo if (has_in_flight) { 46833494fc30STejun Heo bool comma = false; 46843494fc30STejun Heo 46853494fc30STejun Heo pr_info(" in-flight:"); 46863494fc30STejun Heo hash_for_each(pool->busy_hash, bkt, worker, hentry) { 46873494fc30STejun Heo if (worker->current_pwq != pwq) 46883494fc30STejun Heo continue; 46893494fc30STejun Heo 4690d75f773cSSakari Ailus pr_cont("%s %d%s:%ps", comma ? "," : "", 46913494fc30STejun Heo task_pid_nr(worker->task), 469230ae2fc0STejun Heo worker->rescue_wq ? "(RESCUER)" : "", 46933494fc30STejun Heo worker->current_func); 46943494fc30STejun Heo list_for_each_entry(work, &worker->scheduled, entry) 46953494fc30STejun Heo pr_cont_work(false, work); 46963494fc30STejun Heo comma = true; 46973494fc30STejun Heo } 46983494fc30STejun Heo pr_cont("\n"); 46993494fc30STejun Heo } 47003494fc30STejun Heo 47013494fc30STejun Heo list_for_each_entry(work, &pool->worklist, entry) { 47023494fc30STejun Heo if (get_work_pwq(work) == pwq) { 47033494fc30STejun Heo has_pending = true; 47043494fc30STejun Heo break; 47053494fc30STejun Heo } 47063494fc30STejun Heo } 47073494fc30STejun Heo if (has_pending) { 47083494fc30STejun Heo bool comma = false; 47093494fc30STejun Heo 47103494fc30STejun Heo pr_info(" pending:"); 47113494fc30STejun Heo list_for_each_entry(work, &pool->worklist, entry) { 47123494fc30STejun Heo if (get_work_pwq(work) != pwq) 47133494fc30STejun Heo continue; 47143494fc30STejun Heo 47153494fc30STejun Heo pr_cont_work(comma, work); 47163494fc30STejun Heo comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); 47173494fc30STejun Heo } 47183494fc30STejun Heo pr_cont("\n"); 47193494fc30STejun Heo } 47203494fc30STejun Heo 47213494fc30STejun Heo if (!list_empty(&pwq->delayed_works)) { 47223494fc30STejun Heo bool comma = false; 47233494fc30STejun Heo 47243494fc30STejun Heo pr_info(" delayed:"); 47253494fc30STejun Heo list_for_each_entry(work, &pwq->delayed_works, entry) { 47263494fc30STejun Heo pr_cont_work(comma, work); 47273494fc30STejun Heo comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); 47283494fc30STejun Heo } 47293494fc30STejun Heo pr_cont("\n"); 47303494fc30STejun Heo } 47313494fc30STejun Heo } 47323494fc30STejun Heo 47333494fc30STejun Heo /** 47343494fc30STejun Heo * show_workqueue_state - dump workqueue state 47353494fc30STejun Heo * 47367b776af6SRoger Lu * Called from a sysrq handler or try_to_freeze_tasks() and prints out 47377b776af6SRoger Lu * all busy workqueues and pools. 47383494fc30STejun Heo */ 47393494fc30STejun Heo void show_workqueue_state(void) 47403494fc30STejun Heo { 47413494fc30STejun Heo struct workqueue_struct *wq; 47423494fc30STejun Heo struct worker_pool *pool; 47433494fc30STejun Heo unsigned long flags; 47443494fc30STejun Heo int pi; 47453494fc30STejun Heo 474624acfb71SThomas Gleixner rcu_read_lock(); 47473494fc30STejun Heo 47483494fc30STejun Heo pr_info("Showing busy workqueues and worker pools:\n"); 47493494fc30STejun Heo 47503494fc30STejun Heo list_for_each_entry_rcu(wq, &workqueues, list) { 47513494fc30STejun Heo struct pool_workqueue *pwq; 47523494fc30STejun Heo bool idle = true; 47533494fc30STejun Heo 47543494fc30STejun Heo for_each_pwq(pwq, wq) { 47553494fc30STejun Heo if (pwq->nr_active || !list_empty(&pwq->delayed_works)) { 47563494fc30STejun Heo idle = false; 47573494fc30STejun Heo break; 47583494fc30STejun Heo } 47593494fc30STejun Heo } 47603494fc30STejun Heo if (idle) 47613494fc30STejun Heo continue; 47623494fc30STejun Heo 47633494fc30STejun Heo pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags); 47643494fc30STejun Heo 47653494fc30STejun Heo for_each_pwq(pwq, wq) { 47663494fc30STejun Heo spin_lock_irqsave(&pwq->pool->lock, flags); 47673494fc30STejun Heo if (pwq->nr_active || !list_empty(&pwq->delayed_works)) 47683494fc30STejun Heo show_pwq(pwq); 47693494fc30STejun Heo spin_unlock_irqrestore(&pwq->pool->lock, flags); 477062635ea8SSergey Senozhatsky /* 477162635ea8SSergey Senozhatsky * We could be printing a lot from atomic context, e.g. 477262635ea8SSergey Senozhatsky * sysrq-t -> show_workqueue_state(). Avoid triggering 477362635ea8SSergey Senozhatsky * hard lockup. 477462635ea8SSergey Senozhatsky */ 477562635ea8SSergey Senozhatsky touch_nmi_watchdog(); 47763494fc30STejun Heo } 47773494fc30STejun Heo } 47783494fc30STejun Heo 47793494fc30STejun Heo for_each_pool(pool, pi) { 47803494fc30STejun Heo struct worker *worker; 47813494fc30STejun Heo bool first = true; 47823494fc30STejun Heo 47833494fc30STejun Heo spin_lock_irqsave(&pool->lock, flags); 47843494fc30STejun Heo if (pool->nr_workers == pool->nr_idle) 47853494fc30STejun Heo goto next_pool; 47863494fc30STejun Heo 47873494fc30STejun Heo pr_info("pool %d:", pool->id); 47883494fc30STejun Heo pr_cont_pool_info(pool); 478982607adcSTejun Heo pr_cont(" hung=%us workers=%d", 479082607adcSTejun Heo jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000, 479182607adcSTejun Heo pool->nr_workers); 47923494fc30STejun Heo if (pool->manager) 47933494fc30STejun Heo pr_cont(" manager: %d", 47943494fc30STejun Heo task_pid_nr(pool->manager->task)); 47953494fc30STejun Heo list_for_each_entry(worker, &pool->idle_list, entry) { 47963494fc30STejun Heo pr_cont(" %s%d", first ? "idle: " : "", 47973494fc30STejun Heo task_pid_nr(worker->task)); 47983494fc30STejun Heo first = false; 47993494fc30STejun Heo } 48003494fc30STejun Heo pr_cont("\n"); 48013494fc30STejun Heo next_pool: 48023494fc30STejun Heo spin_unlock_irqrestore(&pool->lock, flags); 480362635ea8SSergey Senozhatsky /* 480462635ea8SSergey Senozhatsky * We could be printing a lot from atomic context, e.g. 480562635ea8SSergey Senozhatsky * sysrq-t -> show_workqueue_state(). Avoid triggering 480662635ea8SSergey Senozhatsky * hard lockup. 480762635ea8SSergey Senozhatsky */ 480862635ea8SSergey Senozhatsky touch_nmi_watchdog(); 48093494fc30STejun Heo } 48103494fc30STejun Heo 481124acfb71SThomas Gleixner rcu_read_unlock(); 48123494fc30STejun Heo } 48133494fc30STejun Heo 48146b59808bSTejun Heo /* used to show worker information through /proc/PID/{comm,stat,status} */ 48156b59808bSTejun Heo void wq_worker_comm(char *buf, size_t size, struct task_struct *task) 48166b59808bSTejun Heo { 48176b59808bSTejun Heo int off; 48186b59808bSTejun Heo 48196b59808bSTejun Heo /* always show the actual comm */ 48206b59808bSTejun Heo off = strscpy(buf, task->comm, size); 48216b59808bSTejun Heo if (off < 0) 48226b59808bSTejun Heo return; 48236b59808bSTejun Heo 4824197f6accSTejun Heo /* stabilize PF_WQ_WORKER and worker pool association */ 48256b59808bSTejun Heo mutex_lock(&wq_pool_attach_mutex); 48266b59808bSTejun Heo 4827197f6accSTejun Heo if (task->flags & PF_WQ_WORKER) { 4828197f6accSTejun Heo struct worker *worker = kthread_data(task); 4829197f6accSTejun Heo struct worker_pool *pool = worker->pool; 48306b59808bSTejun Heo 48316b59808bSTejun Heo if (pool) { 48326b59808bSTejun Heo spin_lock_irq(&pool->lock); 48336b59808bSTejun Heo /* 4834197f6accSTejun Heo * ->desc tracks information (wq name or 4835197f6accSTejun Heo * set_worker_desc()) for the latest execution. If 4836197f6accSTejun Heo * current, prepend '+', otherwise '-'. 48376b59808bSTejun Heo */ 48386b59808bSTejun Heo if (worker->desc[0] != '\0') { 48396b59808bSTejun Heo if (worker->current_work) 48406b59808bSTejun Heo scnprintf(buf + off, size - off, "+%s", 48416b59808bSTejun Heo worker->desc); 48426b59808bSTejun Heo else 48436b59808bSTejun Heo scnprintf(buf + off, size - off, "-%s", 48446b59808bSTejun Heo worker->desc); 48456b59808bSTejun Heo } 48466b59808bSTejun Heo spin_unlock_irq(&pool->lock); 48476b59808bSTejun Heo } 4848197f6accSTejun Heo } 48496b59808bSTejun Heo 48506b59808bSTejun Heo mutex_unlock(&wq_pool_attach_mutex); 48516b59808bSTejun Heo } 48526b59808bSTejun Heo 485366448bc2SMathieu Malaterre #ifdef CONFIG_SMP 485466448bc2SMathieu Malaterre 4855db7bccf4STejun Heo /* 4856db7bccf4STejun Heo * CPU hotplug. 4857db7bccf4STejun Heo * 4858e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 4859112202d9STejun Heo * are a lot of assumptions on strong associations among work, pwq and 4860706026c2STejun Heo * pool which make migrating pending and scheduled works very 4861e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 486294cf58bbSTejun Heo * worker pools serve mix of short, long and very long running works making 4863e22bee78STejun Heo * blocked draining impractical. 4864e22bee78STejun Heo * 486524647570STejun Heo * This is solved by allowing the pools to be disassociated from the CPU 4866628c78e7STejun Heo * running as an unbound one and allowing it to be reattached later if the 4867628c78e7STejun Heo * cpu comes back online. 4868db7bccf4STejun Heo */ 4869db7bccf4STejun Heo 4870e8b3f8dbSLai Jiangshan static void unbind_workers(int cpu) 4871db7bccf4STejun Heo { 48724ce62e9eSTejun Heo struct worker_pool *pool; 4873db7bccf4STejun Heo struct worker *worker; 4874db7bccf4STejun Heo 4875f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 48761258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 487794cf58bbSTejun Heo spin_lock_irq(&pool->lock); 4878e22bee78STejun Heo 4879f2d5a0eeSTejun Heo /* 488092f9c5c4SLai Jiangshan * We've blocked all attach/detach operations. Make all workers 488194cf58bbSTejun Heo * unbound and set DISASSOCIATED. Before this, all workers 488294cf58bbSTejun Heo * except for the ones which are still executing works from 488394cf58bbSTejun Heo * before the last CPU down must be on the cpu. After 488494cf58bbSTejun Heo * this, they may become diasporas. 4885f2d5a0eeSTejun Heo */ 4886da028469SLai Jiangshan for_each_pool_worker(worker, pool) 4887403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 4888db7bccf4STejun Heo 488924647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 4890f2d5a0eeSTejun Heo 489194cf58bbSTejun Heo spin_unlock_irq(&pool->lock); 48921258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 4893e22bee78STejun Heo 4894e22bee78STejun Heo /* 4895eb283428SLai Jiangshan * Call schedule() so that we cross rq->lock and thus can 4896eb283428SLai Jiangshan * guarantee sched callbacks see the %WORKER_UNBOUND flag. 4897eb283428SLai Jiangshan * This is necessary as scheduler callbacks may be invoked 4898eb283428SLai Jiangshan * from other cpus. 4899628c78e7STejun Heo */ 4900628c78e7STejun Heo schedule(); 4901628c78e7STejun Heo 4902628c78e7STejun Heo /* 4903eb283428SLai Jiangshan * Sched callbacks are disabled now. Zap nr_running. 4904eb283428SLai Jiangshan * After this, nr_running stays zero and need_more_worker() 4905eb283428SLai Jiangshan * and keep_working() are always true as long as the 4906eb283428SLai Jiangshan * worklist is not empty. This pool now behaves as an 4907eb283428SLai Jiangshan * unbound (in terms of concurrency management) pool which 4908eb283428SLai Jiangshan * are served by workers tied to the pool. 4909e22bee78STejun Heo */ 4910e19e397aSTejun Heo atomic_set(&pool->nr_running, 0); 4911eb283428SLai Jiangshan 4912eb283428SLai Jiangshan /* 4913eb283428SLai Jiangshan * With concurrency management just turned off, a busy 4914eb283428SLai Jiangshan * worker blocking could lead to lengthy stalls. Kick off 4915eb283428SLai Jiangshan * unbound chain execution of currently pending work items. 4916eb283428SLai Jiangshan */ 4917eb283428SLai Jiangshan spin_lock_irq(&pool->lock); 4918eb283428SLai Jiangshan wake_up_worker(pool); 4919eb283428SLai Jiangshan spin_unlock_irq(&pool->lock); 4920eb283428SLai Jiangshan } 4921db7bccf4STejun Heo } 4922db7bccf4STejun Heo 4923bd7c089eSTejun Heo /** 4924bd7c089eSTejun Heo * rebind_workers - rebind all workers of a pool to the associated CPU 4925bd7c089eSTejun Heo * @pool: pool of interest 4926bd7c089eSTejun Heo * 4927a9ab775bSTejun Heo * @pool->cpu is coming online. Rebind all workers to the CPU. 4928bd7c089eSTejun Heo */ 4929bd7c089eSTejun Heo static void rebind_workers(struct worker_pool *pool) 4930bd7c089eSTejun Heo { 4931a9ab775bSTejun Heo struct worker *worker; 4932bd7c089eSTejun Heo 49331258fae7STejun Heo lockdep_assert_held(&wq_pool_attach_mutex); 4934bd7c089eSTejun Heo 4935bd7c089eSTejun Heo /* 4936a9ab775bSTejun Heo * Restore CPU affinity of all workers. As all idle workers should 4937a9ab775bSTejun Heo * be on the run-queue of the associated CPU before any local 4938402dd89dSShailendra Verma * wake-ups for concurrency management happen, restore CPU affinity 4939a9ab775bSTejun Heo * of all workers first and then clear UNBOUND. As we're called 4940a9ab775bSTejun Heo * from CPU_ONLINE, the following shouldn't fail. 4941bd7c089eSTejun Heo */ 4942da028469SLai Jiangshan for_each_pool_worker(worker, pool) 4943a9ab775bSTejun Heo WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, 4944a9ab775bSTejun Heo pool->attrs->cpumask) < 0); 4945a9ab775bSTejun Heo 4946a9ab775bSTejun Heo spin_lock_irq(&pool->lock); 4947f7c17d26SWanpeng Li 49483de5e884SLai Jiangshan pool->flags &= ~POOL_DISASSOCIATED; 4949a9ab775bSTejun Heo 4950da028469SLai Jiangshan for_each_pool_worker(worker, pool) { 4951a9ab775bSTejun Heo unsigned int worker_flags = worker->flags; 4952a9ab775bSTejun Heo 4953a9ab775bSTejun Heo /* 4954a9ab775bSTejun Heo * A bound idle worker should actually be on the runqueue 4955a9ab775bSTejun Heo * of the associated CPU for local wake-ups targeting it to 4956a9ab775bSTejun Heo * work. Kick all idle workers so that they migrate to the 4957a9ab775bSTejun Heo * associated CPU. Doing this in the same loop as 4958a9ab775bSTejun Heo * replacing UNBOUND with REBOUND is safe as no worker will 4959a9ab775bSTejun Heo * be bound before @pool->lock is released. 4960a9ab775bSTejun Heo */ 4961a9ab775bSTejun Heo if (worker_flags & WORKER_IDLE) 4962bd7c089eSTejun Heo wake_up_process(worker->task); 4963bd7c089eSTejun Heo 4964bd7c089eSTejun Heo /* 4965a9ab775bSTejun Heo * We want to clear UNBOUND but can't directly call 4966a9ab775bSTejun Heo * worker_clr_flags() or adjust nr_running. Atomically 4967a9ab775bSTejun Heo * replace UNBOUND with another NOT_RUNNING flag REBOUND. 4968a9ab775bSTejun Heo * @worker will clear REBOUND using worker_clr_flags() when 4969a9ab775bSTejun Heo * it initiates the next execution cycle thus restoring 4970a9ab775bSTejun Heo * concurrency management. Note that when or whether 4971a9ab775bSTejun Heo * @worker clears REBOUND doesn't affect correctness. 4972a9ab775bSTejun Heo * 4973c95491edSMark Rutland * WRITE_ONCE() is necessary because @worker->flags may be 4974a9ab775bSTejun Heo * tested without holding any lock in 49756d25be57SThomas Gleixner * wq_worker_running(). Without it, NOT_RUNNING test may 4976a9ab775bSTejun Heo * fail incorrectly leading to premature concurrency 4977a9ab775bSTejun Heo * management operations. 4978bd7c089eSTejun Heo */ 4979a9ab775bSTejun Heo WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); 4980a9ab775bSTejun Heo worker_flags |= WORKER_REBOUND; 4981a9ab775bSTejun Heo worker_flags &= ~WORKER_UNBOUND; 4982c95491edSMark Rutland WRITE_ONCE(worker->flags, worker_flags); 4983bd7c089eSTejun Heo } 4984a9ab775bSTejun Heo 4985a9ab775bSTejun Heo spin_unlock_irq(&pool->lock); 4986bd7c089eSTejun Heo } 4987bd7c089eSTejun Heo 49887dbc725eSTejun Heo /** 49897dbc725eSTejun Heo * restore_unbound_workers_cpumask - restore cpumask of unbound workers 49907dbc725eSTejun Heo * @pool: unbound pool of interest 49917dbc725eSTejun Heo * @cpu: the CPU which is coming up 49927dbc725eSTejun Heo * 49937dbc725eSTejun Heo * An unbound pool may end up with a cpumask which doesn't have any online 49947dbc725eSTejun Heo * CPUs. When a worker of such pool get scheduled, the scheduler resets 49957dbc725eSTejun Heo * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any 49967dbc725eSTejun Heo * online CPU before, cpus_allowed of all its workers should be restored. 49977dbc725eSTejun Heo */ 49987dbc725eSTejun Heo static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) 49997dbc725eSTejun Heo { 50007dbc725eSTejun Heo static cpumask_t cpumask; 50017dbc725eSTejun Heo struct worker *worker; 50027dbc725eSTejun Heo 50031258fae7STejun Heo lockdep_assert_held(&wq_pool_attach_mutex); 50047dbc725eSTejun Heo 50057dbc725eSTejun Heo /* is @cpu allowed for @pool? */ 50067dbc725eSTejun Heo if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) 50077dbc725eSTejun Heo return; 50087dbc725eSTejun Heo 50097dbc725eSTejun Heo cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); 50107dbc725eSTejun Heo 50117dbc725eSTejun Heo /* as we're called from CPU_ONLINE, the following shouldn't fail */ 5012da028469SLai Jiangshan for_each_pool_worker(worker, pool) 5013d945b5e9SPeter Zijlstra WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0); 50147dbc725eSTejun Heo } 50157dbc725eSTejun Heo 50167ee681b2SThomas Gleixner int workqueue_prepare_cpu(unsigned int cpu) 50171da177e4SLinus Torvalds { 50184ce62e9eSTejun Heo struct worker_pool *pool; 50191da177e4SLinus Torvalds 5020f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 50213ce63377STejun Heo if (pool->nr_workers) 50223ce63377STejun Heo continue; 5023051e1850SLai Jiangshan if (!create_worker(pool)) 50247ee681b2SThomas Gleixner return -ENOMEM; 50253af24433SOleg Nesterov } 50267ee681b2SThomas Gleixner return 0; 50277ee681b2SThomas Gleixner } 50281da177e4SLinus Torvalds 50297ee681b2SThomas Gleixner int workqueue_online_cpu(unsigned int cpu) 50307ee681b2SThomas Gleixner { 50317ee681b2SThomas Gleixner struct worker_pool *pool; 50327ee681b2SThomas Gleixner struct workqueue_struct *wq; 50337ee681b2SThomas Gleixner int pi; 50347ee681b2SThomas Gleixner 503568e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 50367dbc725eSTejun Heo 50377dbc725eSTejun Heo for_each_pool(pool, pi) { 50381258fae7STejun Heo mutex_lock(&wq_pool_attach_mutex); 503994cf58bbSTejun Heo 5040f05b558dSLai Jiangshan if (pool->cpu == cpu) 504194cf58bbSTejun Heo rebind_workers(pool); 5042f05b558dSLai Jiangshan else if (pool->cpu < 0) 50437dbc725eSTejun Heo restore_unbound_workers_cpumask(pool, cpu); 504494cf58bbSTejun Heo 50451258fae7STejun Heo mutex_unlock(&wq_pool_attach_mutex); 504694cf58bbSTejun Heo } 50477dbc725eSTejun Heo 50484c16bd32STejun Heo /* update NUMA affinity of unbound workqueues */ 50494c16bd32STejun Heo list_for_each_entry(wq, &workqueues, list) 50504c16bd32STejun Heo wq_update_unbound_numa(wq, cpu, true); 50514c16bd32STejun Heo 505268e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 50537ee681b2SThomas Gleixner return 0; 505465758202STejun Heo } 505565758202STejun Heo 50567ee681b2SThomas Gleixner int workqueue_offline_cpu(unsigned int cpu) 505765758202STejun Heo { 50584c16bd32STejun Heo struct workqueue_struct *wq; 50598db25e78STejun Heo 50604c16bd32STejun Heo /* unbinding per-cpu workers should happen on the local CPU */ 5061e8b3f8dbSLai Jiangshan if (WARN_ON(cpu != smp_processor_id())) 5062e8b3f8dbSLai Jiangshan return -1; 5063e8b3f8dbSLai Jiangshan 5064e8b3f8dbSLai Jiangshan unbind_workers(cpu); 50654c16bd32STejun Heo 50664c16bd32STejun Heo /* update NUMA affinity of unbound workqueues */ 50674c16bd32STejun Heo mutex_lock(&wq_pool_mutex); 50684c16bd32STejun Heo list_for_each_entry(wq, &workqueues, list) 50694c16bd32STejun Heo wq_update_unbound_numa(wq, cpu, false); 50704c16bd32STejun Heo mutex_unlock(&wq_pool_mutex); 50714c16bd32STejun Heo 50727ee681b2SThomas Gleixner return 0; 507365758202STejun Heo } 507465758202STejun Heo 50752d3854a3SRusty Russell struct work_for_cpu { 5076ed48ece2STejun Heo struct work_struct work; 50772d3854a3SRusty Russell long (*fn)(void *); 50782d3854a3SRusty Russell void *arg; 50792d3854a3SRusty Russell long ret; 50802d3854a3SRusty Russell }; 50812d3854a3SRusty Russell 5082ed48ece2STejun Heo static void work_for_cpu_fn(struct work_struct *work) 50832d3854a3SRusty Russell { 5084ed48ece2STejun Heo struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); 5085ed48ece2STejun Heo 50862d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 50872d3854a3SRusty Russell } 50882d3854a3SRusty Russell 50892d3854a3SRusty Russell /** 509022aceb31SAnna-Maria Gleixner * work_on_cpu - run a function in thread context on a particular cpu 50912d3854a3SRusty Russell * @cpu: the cpu to run on 50922d3854a3SRusty Russell * @fn: the function to run 50932d3854a3SRusty Russell * @arg: the function arg 50942d3854a3SRusty Russell * 509531ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 50966b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 5097d185af30SYacine Belkadi * 5098d185af30SYacine Belkadi * Return: The value @fn returns. 50992d3854a3SRusty Russell */ 5100d84ff051STejun Heo long work_on_cpu(int cpu, long (*fn)(void *), void *arg) 51012d3854a3SRusty Russell { 5102ed48ece2STejun Heo struct work_for_cpu wfc = { .fn = fn, .arg = arg }; 51032d3854a3SRusty Russell 5104ed48ece2STejun Heo INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); 5105ed48ece2STejun Heo schedule_work_on(cpu, &wfc.work); 510612997d1aSBjorn Helgaas flush_work(&wfc.work); 5107440a1136SChuansheng Liu destroy_work_on_stack(&wfc.work); 51082d3854a3SRusty Russell return wfc.ret; 51092d3854a3SRusty Russell } 51102d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 51110e8d6a93SThomas Gleixner 51120e8d6a93SThomas Gleixner /** 51130e8d6a93SThomas Gleixner * work_on_cpu_safe - run a function in thread context on a particular cpu 51140e8d6a93SThomas Gleixner * @cpu: the cpu to run on 51150e8d6a93SThomas Gleixner * @fn: the function to run 51160e8d6a93SThomas Gleixner * @arg: the function argument 51170e8d6a93SThomas Gleixner * 51180e8d6a93SThomas Gleixner * Disables CPU hotplug and calls work_on_cpu(). The caller must not hold 51190e8d6a93SThomas Gleixner * any locks which would prevent @fn from completing. 51200e8d6a93SThomas Gleixner * 51210e8d6a93SThomas Gleixner * Return: The value @fn returns. 51220e8d6a93SThomas Gleixner */ 51230e8d6a93SThomas Gleixner long work_on_cpu_safe(int cpu, long (*fn)(void *), void *arg) 51240e8d6a93SThomas Gleixner { 51250e8d6a93SThomas Gleixner long ret = -ENODEV; 51260e8d6a93SThomas Gleixner 51270e8d6a93SThomas Gleixner get_online_cpus(); 51280e8d6a93SThomas Gleixner if (cpu_online(cpu)) 51290e8d6a93SThomas Gleixner ret = work_on_cpu(cpu, fn, arg); 51300e8d6a93SThomas Gleixner put_online_cpus(); 51310e8d6a93SThomas Gleixner return ret; 51320e8d6a93SThomas Gleixner } 51330e8d6a93SThomas Gleixner EXPORT_SYMBOL_GPL(work_on_cpu_safe); 51342d3854a3SRusty Russell #endif /* CONFIG_SMP */ 51352d3854a3SRusty Russell 5136a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 5137e7577c50SRusty Russell 5138a0a1a5fdSTejun Heo /** 5139a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 5140a0a1a5fdSTejun Heo * 514158a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 5142c5aa87bbSTejun Heo * workqueues will queue new works to their delayed_works list instead of 5143706026c2STejun Heo * pool->worklist. 5144a0a1a5fdSTejun Heo * 5145a0a1a5fdSTejun Heo * CONTEXT: 5146a357fc03SLai Jiangshan * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 5147a0a1a5fdSTejun Heo */ 5148a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 5149a0a1a5fdSTejun Heo { 515024b8a847STejun Heo struct workqueue_struct *wq; 515124b8a847STejun Heo struct pool_workqueue *pwq; 5152a0a1a5fdSTejun Heo 515368e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5154a0a1a5fdSTejun Heo 51556183c009STejun Heo WARN_ON_ONCE(workqueue_freezing); 5156a0a1a5fdSTejun Heo workqueue_freezing = true; 5157a0a1a5fdSTejun Heo 515824b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 5159a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 5160699ce097STejun Heo for_each_pwq(pwq, wq) 5161699ce097STejun Heo pwq_adjust_max_active(pwq); 5162a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 5163a1056305STejun Heo } 51645bcab335STejun Heo 516568e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5166a0a1a5fdSTejun Heo } 5167a0a1a5fdSTejun Heo 5168a0a1a5fdSTejun Heo /** 516958a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 5170a0a1a5fdSTejun Heo * 5171a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 5172a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 5173a0a1a5fdSTejun Heo * 5174a0a1a5fdSTejun Heo * CONTEXT: 517568e13a67SLai Jiangshan * Grabs and releases wq_pool_mutex. 5176a0a1a5fdSTejun Heo * 5177d185af30SYacine Belkadi * Return: 517858a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 517958a69cb4STejun Heo * is complete. 5180a0a1a5fdSTejun Heo */ 5181a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 5182a0a1a5fdSTejun Heo { 5183a0a1a5fdSTejun Heo bool busy = false; 518424b8a847STejun Heo struct workqueue_struct *wq; 518524b8a847STejun Heo struct pool_workqueue *pwq; 5186a0a1a5fdSTejun Heo 518768e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5188a0a1a5fdSTejun Heo 51896183c009STejun Heo WARN_ON_ONCE(!workqueue_freezing); 5190a0a1a5fdSTejun Heo 519124b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 519224b8a847STejun Heo if (!(wq->flags & WQ_FREEZABLE)) 519324b8a847STejun Heo continue; 5194a0a1a5fdSTejun Heo /* 5195a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 5196a0a1a5fdSTejun Heo * to peek without lock. 5197a0a1a5fdSTejun Heo */ 519824acfb71SThomas Gleixner rcu_read_lock(); 519924b8a847STejun Heo for_each_pwq(pwq, wq) { 52006183c009STejun Heo WARN_ON_ONCE(pwq->nr_active < 0); 5201112202d9STejun Heo if (pwq->nr_active) { 5202a0a1a5fdSTejun Heo busy = true; 520324acfb71SThomas Gleixner rcu_read_unlock(); 5204a0a1a5fdSTejun Heo goto out_unlock; 5205a0a1a5fdSTejun Heo } 5206a0a1a5fdSTejun Heo } 520724acfb71SThomas Gleixner rcu_read_unlock(); 5208a0a1a5fdSTejun Heo } 5209a0a1a5fdSTejun Heo out_unlock: 521068e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5211a0a1a5fdSTejun Heo return busy; 5212a0a1a5fdSTejun Heo } 5213a0a1a5fdSTejun Heo 5214a0a1a5fdSTejun Heo /** 5215a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 5216a0a1a5fdSTejun Heo * 5217a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 5218706026c2STejun Heo * frozen works are transferred to their respective pool worklists. 5219a0a1a5fdSTejun Heo * 5220a0a1a5fdSTejun Heo * CONTEXT: 5221a357fc03SLai Jiangshan * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 5222a0a1a5fdSTejun Heo */ 5223a0a1a5fdSTejun Heo void thaw_workqueues(void) 5224a0a1a5fdSTejun Heo { 522524b8a847STejun Heo struct workqueue_struct *wq; 522624b8a847STejun Heo struct pool_workqueue *pwq; 5227a0a1a5fdSTejun Heo 522868e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 5229a0a1a5fdSTejun Heo 5230a0a1a5fdSTejun Heo if (!workqueue_freezing) 5231a0a1a5fdSTejun Heo goto out_unlock; 5232a0a1a5fdSTejun Heo 523374b414eaSLai Jiangshan workqueue_freezing = false; 523424b8a847STejun Heo 523524b8a847STejun Heo /* restore max_active and repopulate worklist */ 523624b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 5237a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 5238699ce097STejun Heo for_each_pwq(pwq, wq) 5239699ce097STejun Heo pwq_adjust_max_active(pwq); 5240a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 524124b8a847STejun Heo } 524224b8a847STejun Heo 5243a0a1a5fdSTejun Heo out_unlock: 524468e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5245a0a1a5fdSTejun Heo } 5246a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 5247a0a1a5fdSTejun Heo 5248042f7df1SLai Jiangshan static int workqueue_apply_unbound_cpumask(void) 5249042f7df1SLai Jiangshan { 5250042f7df1SLai Jiangshan LIST_HEAD(ctxs); 5251042f7df1SLai Jiangshan int ret = 0; 5252042f7df1SLai Jiangshan struct workqueue_struct *wq; 5253042f7df1SLai Jiangshan struct apply_wqattrs_ctx *ctx, *n; 5254042f7df1SLai Jiangshan 5255042f7df1SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 5256042f7df1SLai Jiangshan 5257042f7df1SLai Jiangshan list_for_each_entry(wq, &workqueues, list) { 5258042f7df1SLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 5259042f7df1SLai Jiangshan continue; 5260042f7df1SLai Jiangshan /* creating multiple pwqs breaks ordering guarantee */ 5261042f7df1SLai Jiangshan if (wq->flags & __WQ_ORDERED) 5262042f7df1SLai Jiangshan continue; 5263042f7df1SLai Jiangshan 5264042f7df1SLai Jiangshan ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs); 5265042f7df1SLai Jiangshan if (!ctx) { 5266042f7df1SLai Jiangshan ret = -ENOMEM; 5267042f7df1SLai Jiangshan break; 5268042f7df1SLai Jiangshan } 5269042f7df1SLai Jiangshan 5270042f7df1SLai Jiangshan list_add_tail(&ctx->list, &ctxs); 5271042f7df1SLai Jiangshan } 5272042f7df1SLai Jiangshan 5273042f7df1SLai Jiangshan list_for_each_entry_safe(ctx, n, &ctxs, list) { 5274042f7df1SLai Jiangshan if (!ret) 5275042f7df1SLai Jiangshan apply_wqattrs_commit(ctx); 5276042f7df1SLai Jiangshan apply_wqattrs_cleanup(ctx); 5277042f7df1SLai Jiangshan } 5278042f7df1SLai Jiangshan 5279042f7df1SLai Jiangshan return ret; 5280042f7df1SLai Jiangshan } 5281042f7df1SLai Jiangshan 5282042f7df1SLai Jiangshan /** 5283042f7df1SLai Jiangshan * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask 5284042f7df1SLai Jiangshan * @cpumask: the cpumask to set 5285042f7df1SLai Jiangshan * 5286042f7df1SLai Jiangshan * The low-level workqueues cpumask is a global cpumask that limits 5287042f7df1SLai Jiangshan * the affinity of all unbound workqueues. This function check the @cpumask 5288042f7df1SLai Jiangshan * and apply it to all unbound workqueues and updates all pwqs of them. 5289042f7df1SLai Jiangshan * 5290042f7df1SLai Jiangshan * Retun: 0 - Success 5291042f7df1SLai Jiangshan * -EINVAL - Invalid @cpumask 5292042f7df1SLai Jiangshan * -ENOMEM - Failed to allocate memory for attrs or pwqs. 5293042f7df1SLai Jiangshan */ 5294042f7df1SLai Jiangshan int workqueue_set_unbound_cpumask(cpumask_var_t cpumask) 5295042f7df1SLai Jiangshan { 5296042f7df1SLai Jiangshan int ret = -EINVAL; 5297042f7df1SLai Jiangshan cpumask_var_t saved_cpumask; 5298042f7df1SLai Jiangshan 5299042f7df1SLai Jiangshan if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL)) 5300042f7df1SLai Jiangshan return -ENOMEM; 5301042f7df1SLai Jiangshan 5302c98a9805STal Shorer /* 5303c98a9805STal Shorer * Not excluding isolated cpus on purpose. 5304c98a9805STal Shorer * If the user wishes to include them, we allow that. 5305c98a9805STal Shorer */ 5306042f7df1SLai Jiangshan cpumask_and(cpumask, cpumask, cpu_possible_mask); 5307042f7df1SLai Jiangshan if (!cpumask_empty(cpumask)) { 5308a0111cf6SLai Jiangshan apply_wqattrs_lock(); 5309042f7df1SLai Jiangshan 5310042f7df1SLai Jiangshan /* save the old wq_unbound_cpumask. */ 5311042f7df1SLai Jiangshan cpumask_copy(saved_cpumask, wq_unbound_cpumask); 5312042f7df1SLai Jiangshan 5313042f7df1SLai Jiangshan /* update wq_unbound_cpumask at first and apply it to wqs. */ 5314042f7df1SLai Jiangshan cpumask_copy(wq_unbound_cpumask, cpumask); 5315042f7df1SLai Jiangshan ret = workqueue_apply_unbound_cpumask(); 5316042f7df1SLai Jiangshan 5317042f7df1SLai Jiangshan /* restore the wq_unbound_cpumask when failed. */ 5318042f7df1SLai Jiangshan if (ret < 0) 5319042f7df1SLai Jiangshan cpumask_copy(wq_unbound_cpumask, saved_cpumask); 5320042f7df1SLai Jiangshan 5321a0111cf6SLai Jiangshan apply_wqattrs_unlock(); 5322042f7df1SLai Jiangshan } 5323042f7df1SLai Jiangshan 5324042f7df1SLai Jiangshan free_cpumask_var(saved_cpumask); 5325042f7df1SLai Jiangshan return ret; 5326042f7df1SLai Jiangshan } 5327042f7df1SLai Jiangshan 53286ba94429SFrederic Weisbecker #ifdef CONFIG_SYSFS 53296ba94429SFrederic Weisbecker /* 53306ba94429SFrederic Weisbecker * Workqueues with WQ_SYSFS flag set is visible to userland via 53316ba94429SFrederic Weisbecker * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the 53326ba94429SFrederic Weisbecker * following attributes. 53336ba94429SFrederic Weisbecker * 53346ba94429SFrederic Weisbecker * per_cpu RO bool : whether the workqueue is per-cpu or unbound 53356ba94429SFrederic Weisbecker * max_active RW int : maximum number of in-flight work items 53366ba94429SFrederic Weisbecker * 53376ba94429SFrederic Weisbecker * Unbound workqueues have the following extra attributes. 53386ba94429SFrederic Weisbecker * 53399a19b463SWang Long * pool_ids RO int : the associated pool IDs for each node 53406ba94429SFrederic Weisbecker * nice RW int : nice value of the workers 53416ba94429SFrederic Weisbecker * cpumask RW mask : bitmask of allowed CPUs for the workers 53429a19b463SWang Long * numa RW bool : whether enable NUMA affinity 53436ba94429SFrederic Weisbecker */ 53446ba94429SFrederic Weisbecker struct wq_device { 53456ba94429SFrederic Weisbecker struct workqueue_struct *wq; 53466ba94429SFrederic Weisbecker struct device dev; 53476ba94429SFrederic Weisbecker }; 53486ba94429SFrederic Weisbecker 53496ba94429SFrederic Weisbecker static struct workqueue_struct *dev_to_wq(struct device *dev) 53506ba94429SFrederic Weisbecker { 53516ba94429SFrederic Weisbecker struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 53526ba94429SFrederic Weisbecker 53536ba94429SFrederic Weisbecker return wq_dev->wq; 53546ba94429SFrederic Weisbecker } 53556ba94429SFrederic Weisbecker 53566ba94429SFrederic Weisbecker static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, 53576ba94429SFrederic Weisbecker char *buf) 53586ba94429SFrederic Weisbecker { 53596ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 53606ba94429SFrederic Weisbecker 53616ba94429SFrederic Weisbecker return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); 53626ba94429SFrederic Weisbecker } 53636ba94429SFrederic Weisbecker static DEVICE_ATTR_RO(per_cpu); 53646ba94429SFrederic Weisbecker 53656ba94429SFrederic Weisbecker static ssize_t max_active_show(struct device *dev, 53666ba94429SFrederic Weisbecker struct device_attribute *attr, char *buf) 53676ba94429SFrederic Weisbecker { 53686ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 53696ba94429SFrederic Weisbecker 53706ba94429SFrederic Weisbecker return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); 53716ba94429SFrederic Weisbecker } 53726ba94429SFrederic Weisbecker 53736ba94429SFrederic Weisbecker static ssize_t max_active_store(struct device *dev, 53746ba94429SFrederic Weisbecker struct device_attribute *attr, const char *buf, 53756ba94429SFrederic Weisbecker size_t count) 53766ba94429SFrederic Weisbecker { 53776ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 53786ba94429SFrederic Weisbecker int val; 53796ba94429SFrederic Weisbecker 53806ba94429SFrederic Weisbecker if (sscanf(buf, "%d", &val) != 1 || val <= 0) 53816ba94429SFrederic Weisbecker return -EINVAL; 53826ba94429SFrederic Weisbecker 53836ba94429SFrederic Weisbecker workqueue_set_max_active(wq, val); 53846ba94429SFrederic Weisbecker return count; 53856ba94429SFrederic Weisbecker } 53866ba94429SFrederic Weisbecker static DEVICE_ATTR_RW(max_active); 53876ba94429SFrederic Weisbecker 53886ba94429SFrederic Weisbecker static struct attribute *wq_sysfs_attrs[] = { 53896ba94429SFrederic Weisbecker &dev_attr_per_cpu.attr, 53906ba94429SFrederic Weisbecker &dev_attr_max_active.attr, 53916ba94429SFrederic Weisbecker NULL, 53926ba94429SFrederic Weisbecker }; 53936ba94429SFrederic Weisbecker ATTRIBUTE_GROUPS(wq_sysfs); 53946ba94429SFrederic Weisbecker 53956ba94429SFrederic Weisbecker static ssize_t wq_pool_ids_show(struct device *dev, 53966ba94429SFrederic Weisbecker struct device_attribute *attr, char *buf) 53976ba94429SFrederic Weisbecker { 53986ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 53996ba94429SFrederic Weisbecker const char *delim = ""; 54006ba94429SFrederic Weisbecker int node, written = 0; 54016ba94429SFrederic Weisbecker 540224acfb71SThomas Gleixner get_online_cpus(); 540324acfb71SThomas Gleixner rcu_read_lock(); 54046ba94429SFrederic Weisbecker for_each_node(node) { 54056ba94429SFrederic Weisbecker written += scnprintf(buf + written, PAGE_SIZE - written, 54066ba94429SFrederic Weisbecker "%s%d:%d", delim, node, 54076ba94429SFrederic Weisbecker unbound_pwq_by_node(wq, node)->pool->id); 54086ba94429SFrederic Weisbecker delim = " "; 54096ba94429SFrederic Weisbecker } 54106ba94429SFrederic Weisbecker written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); 541124acfb71SThomas Gleixner rcu_read_unlock(); 541224acfb71SThomas Gleixner put_online_cpus(); 54136ba94429SFrederic Weisbecker 54146ba94429SFrederic Weisbecker return written; 54156ba94429SFrederic Weisbecker } 54166ba94429SFrederic Weisbecker 54176ba94429SFrederic Weisbecker static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, 54186ba94429SFrederic Weisbecker char *buf) 54196ba94429SFrederic Weisbecker { 54206ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 54216ba94429SFrederic Weisbecker int written; 54226ba94429SFrederic Weisbecker 54236ba94429SFrederic Weisbecker mutex_lock(&wq->mutex); 54246ba94429SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); 54256ba94429SFrederic Weisbecker mutex_unlock(&wq->mutex); 54266ba94429SFrederic Weisbecker 54276ba94429SFrederic Weisbecker return written; 54286ba94429SFrederic Weisbecker } 54296ba94429SFrederic Weisbecker 54306ba94429SFrederic Weisbecker /* prepare workqueue_attrs for sysfs store operations */ 54316ba94429SFrederic Weisbecker static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) 54326ba94429SFrederic Weisbecker { 54336ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 54346ba94429SFrederic Weisbecker 5435899a94feSLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 5436899a94feSLai Jiangshan 5437be69d00dSThomas Gleixner attrs = alloc_workqueue_attrs(); 54386ba94429SFrederic Weisbecker if (!attrs) 54396ba94429SFrederic Weisbecker return NULL; 54406ba94429SFrederic Weisbecker 54416ba94429SFrederic Weisbecker copy_workqueue_attrs(attrs, wq->unbound_attrs); 54426ba94429SFrederic Weisbecker return attrs; 54436ba94429SFrederic Weisbecker } 54446ba94429SFrederic Weisbecker 54456ba94429SFrederic Weisbecker static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, 54466ba94429SFrederic Weisbecker const char *buf, size_t count) 54476ba94429SFrederic Weisbecker { 54486ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 54496ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 5450d4d3e257SLai Jiangshan int ret = -ENOMEM; 5451d4d3e257SLai Jiangshan 5452d4d3e257SLai Jiangshan apply_wqattrs_lock(); 54536ba94429SFrederic Weisbecker 54546ba94429SFrederic Weisbecker attrs = wq_sysfs_prep_attrs(wq); 54556ba94429SFrederic Weisbecker if (!attrs) 5456d4d3e257SLai Jiangshan goto out_unlock; 54576ba94429SFrederic Weisbecker 54586ba94429SFrederic Weisbecker if (sscanf(buf, "%d", &attrs->nice) == 1 && 54596ba94429SFrederic Weisbecker attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) 5460d4d3e257SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 54616ba94429SFrederic Weisbecker else 54626ba94429SFrederic Weisbecker ret = -EINVAL; 54636ba94429SFrederic Weisbecker 5464d4d3e257SLai Jiangshan out_unlock: 5465d4d3e257SLai Jiangshan apply_wqattrs_unlock(); 54666ba94429SFrederic Weisbecker free_workqueue_attrs(attrs); 54676ba94429SFrederic Weisbecker return ret ?: count; 54686ba94429SFrederic Weisbecker } 54696ba94429SFrederic Weisbecker 54706ba94429SFrederic Weisbecker static ssize_t wq_cpumask_show(struct device *dev, 54716ba94429SFrederic Weisbecker struct device_attribute *attr, char *buf) 54726ba94429SFrederic Weisbecker { 54736ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 54746ba94429SFrederic Weisbecker int written; 54756ba94429SFrederic Weisbecker 54766ba94429SFrederic Weisbecker mutex_lock(&wq->mutex); 54776ba94429SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%*pb\n", 54786ba94429SFrederic Weisbecker cpumask_pr_args(wq->unbound_attrs->cpumask)); 54796ba94429SFrederic Weisbecker mutex_unlock(&wq->mutex); 54806ba94429SFrederic Weisbecker return written; 54816ba94429SFrederic Weisbecker } 54826ba94429SFrederic Weisbecker 54836ba94429SFrederic Weisbecker static ssize_t wq_cpumask_store(struct device *dev, 54846ba94429SFrederic Weisbecker struct device_attribute *attr, 54856ba94429SFrederic Weisbecker const char *buf, size_t count) 54866ba94429SFrederic Weisbecker { 54876ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 54886ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 5489d4d3e257SLai Jiangshan int ret = -ENOMEM; 5490d4d3e257SLai Jiangshan 5491d4d3e257SLai Jiangshan apply_wqattrs_lock(); 54926ba94429SFrederic Weisbecker 54936ba94429SFrederic Weisbecker attrs = wq_sysfs_prep_attrs(wq); 54946ba94429SFrederic Weisbecker if (!attrs) 5495d4d3e257SLai Jiangshan goto out_unlock; 54966ba94429SFrederic Weisbecker 54976ba94429SFrederic Weisbecker ret = cpumask_parse(buf, attrs->cpumask); 54986ba94429SFrederic Weisbecker if (!ret) 5499d4d3e257SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 55006ba94429SFrederic Weisbecker 5501d4d3e257SLai Jiangshan out_unlock: 5502d4d3e257SLai Jiangshan apply_wqattrs_unlock(); 55036ba94429SFrederic Weisbecker free_workqueue_attrs(attrs); 55046ba94429SFrederic Weisbecker return ret ?: count; 55056ba94429SFrederic Weisbecker } 55066ba94429SFrederic Weisbecker 55076ba94429SFrederic Weisbecker static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, 55086ba94429SFrederic Weisbecker char *buf) 55096ba94429SFrederic Weisbecker { 55106ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 55116ba94429SFrederic Weisbecker int written; 55126ba94429SFrederic Weisbecker 55136ba94429SFrederic Weisbecker mutex_lock(&wq->mutex); 55146ba94429SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%d\n", 55156ba94429SFrederic Weisbecker !wq->unbound_attrs->no_numa); 55166ba94429SFrederic Weisbecker mutex_unlock(&wq->mutex); 55176ba94429SFrederic Weisbecker 55186ba94429SFrederic Weisbecker return written; 55196ba94429SFrederic Weisbecker } 55206ba94429SFrederic Weisbecker 55216ba94429SFrederic Weisbecker static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, 55226ba94429SFrederic Weisbecker const char *buf, size_t count) 55236ba94429SFrederic Weisbecker { 55246ba94429SFrederic Weisbecker struct workqueue_struct *wq = dev_to_wq(dev); 55256ba94429SFrederic Weisbecker struct workqueue_attrs *attrs; 5526d4d3e257SLai Jiangshan int v, ret = -ENOMEM; 5527d4d3e257SLai Jiangshan 5528d4d3e257SLai Jiangshan apply_wqattrs_lock(); 55296ba94429SFrederic Weisbecker 55306ba94429SFrederic Weisbecker attrs = wq_sysfs_prep_attrs(wq); 55316ba94429SFrederic Weisbecker if (!attrs) 5532d4d3e257SLai Jiangshan goto out_unlock; 55336ba94429SFrederic Weisbecker 55346ba94429SFrederic Weisbecker ret = -EINVAL; 55356ba94429SFrederic Weisbecker if (sscanf(buf, "%d", &v) == 1) { 55366ba94429SFrederic Weisbecker attrs->no_numa = !v; 5537d4d3e257SLai Jiangshan ret = apply_workqueue_attrs_locked(wq, attrs); 55386ba94429SFrederic Weisbecker } 55396ba94429SFrederic Weisbecker 5540d4d3e257SLai Jiangshan out_unlock: 5541d4d3e257SLai Jiangshan apply_wqattrs_unlock(); 55426ba94429SFrederic Weisbecker free_workqueue_attrs(attrs); 55436ba94429SFrederic Weisbecker return ret ?: count; 55446ba94429SFrederic Weisbecker } 55456ba94429SFrederic Weisbecker 55466ba94429SFrederic Weisbecker static struct device_attribute wq_sysfs_unbound_attrs[] = { 55476ba94429SFrederic Weisbecker __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), 55486ba94429SFrederic Weisbecker __ATTR(nice, 0644, wq_nice_show, wq_nice_store), 55496ba94429SFrederic Weisbecker __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), 55506ba94429SFrederic Weisbecker __ATTR(numa, 0644, wq_numa_show, wq_numa_store), 55516ba94429SFrederic Weisbecker __ATTR_NULL, 55526ba94429SFrederic Weisbecker }; 55536ba94429SFrederic Weisbecker 55546ba94429SFrederic Weisbecker static struct bus_type wq_subsys = { 55556ba94429SFrederic Weisbecker .name = "workqueue", 55566ba94429SFrederic Weisbecker .dev_groups = wq_sysfs_groups, 55576ba94429SFrederic Weisbecker }; 55586ba94429SFrederic Weisbecker 5559b05a7928SFrederic Weisbecker static ssize_t wq_unbound_cpumask_show(struct device *dev, 5560b05a7928SFrederic Weisbecker struct device_attribute *attr, char *buf) 5561b05a7928SFrederic Weisbecker { 5562b05a7928SFrederic Weisbecker int written; 5563b05a7928SFrederic Weisbecker 5564042f7df1SLai Jiangshan mutex_lock(&wq_pool_mutex); 5565b05a7928SFrederic Weisbecker written = scnprintf(buf, PAGE_SIZE, "%*pb\n", 5566b05a7928SFrederic Weisbecker cpumask_pr_args(wq_unbound_cpumask)); 5567042f7df1SLai Jiangshan mutex_unlock(&wq_pool_mutex); 5568b05a7928SFrederic Weisbecker 5569b05a7928SFrederic Weisbecker return written; 5570b05a7928SFrederic Weisbecker } 5571b05a7928SFrederic Weisbecker 5572042f7df1SLai Jiangshan static ssize_t wq_unbound_cpumask_store(struct device *dev, 5573042f7df1SLai Jiangshan struct device_attribute *attr, const char *buf, size_t count) 5574042f7df1SLai Jiangshan { 5575042f7df1SLai Jiangshan cpumask_var_t cpumask; 5576042f7df1SLai Jiangshan int ret; 5577042f7df1SLai Jiangshan 5578042f7df1SLai Jiangshan if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) 5579042f7df1SLai Jiangshan return -ENOMEM; 5580042f7df1SLai Jiangshan 5581042f7df1SLai Jiangshan ret = cpumask_parse(buf, cpumask); 5582042f7df1SLai Jiangshan if (!ret) 5583042f7df1SLai Jiangshan ret = workqueue_set_unbound_cpumask(cpumask); 5584042f7df1SLai Jiangshan 5585042f7df1SLai Jiangshan free_cpumask_var(cpumask); 5586042f7df1SLai Jiangshan return ret ? ret : count; 5587042f7df1SLai Jiangshan } 5588042f7df1SLai Jiangshan 5589b05a7928SFrederic Weisbecker static struct device_attribute wq_sysfs_cpumask_attr = 5590042f7df1SLai Jiangshan __ATTR(cpumask, 0644, wq_unbound_cpumask_show, 5591042f7df1SLai Jiangshan wq_unbound_cpumask_store); 5592b05a7928SFrederic Weisbecker 55936ba94429SFrederic Weisbecker static int __init wq_sysfs_init(void) 55946ba94429SFrederic Weisbecker { 5595b05a7928SFrederic Weisbecker int err; 5596b05a7928SFrederic Weisbecker 5597b05a7928SFrederic Weisbecker err = subsys_virtual_register(&wq_subsys, NULL); 5598b05a7928SFrederic Weisbecker if (err) 5599b05a7928SFrederic Weisbecker return err; 5600b05a7928SFrederic Weisbecker 5601b05a7928SFrederic Weisbecker return device_create_file(wq_subsys.dev_root, &wq_sysfs_cpumask_attr); 56026ba94429SFrederic Weisbecker } 56036ba94429SFrederic Weisbecker core_initcall(wq_sysfs_init); 56046ba94429SFrederic Weisbecker 56056ba94429SFrederic Weisbecker static void wq_device_release(struct device *dev) 56066ba94429SFrederic Weisbecker { 56076ba94429SFrederic Weisbecker struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 56086ba94429SFrederic Weisbecker 56096ba94429SFrederic Weisbecker kfree(wq_dev); 56106ba94429SFrederic Weisbecker } 56116ba94429SFrederic Weisbecker 56126ba94429SFrederic Weisbecker /** 56136ba94429SFrederic Weisbecker * workqueue_sysfs_register - make a workqueue visible in sysfs 56146ba94429SFrederic Weisbecker * @wq: the workqueue to register 56156ba94429SFrederic Weisbecker * 56166ba94429SFrederic Weisbecker * Expose @wq in sysfs under /sys/bus/workqueue/devices. 56176ba94429SFrederic Weisbecker * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set 56186ba94429SFrederic Weisbecker * which is the preferred method. 56196ba94429SFrederic Weisbecker * 56206ba94429SFrederic Weisbecker * Workqueue user should use this function directly iff it wants to apply 56216ba94429SFrederic Weisbecker * workqueue_attrs before making the workqueue visible in sysfs; otherwise, 56226ba94429SFrederic Weisbecker * apply_workqueue_attrs() may race against userland updating the 56236ba94429SFrederic Weisbecker * attributes. 56246ba94429SFrederic Weisbecker * 56256ba94429SFrederic Weisbecker * Return: 0 on success, -errno on failure. 56266ba94429SFrederic Weisbecker */ 56276ba94429SFrederic Weisbecker int workqueue_sysfs_register(struct workqueue_struct *wq) 56286ba94429SFrederic Weisbecker { 56296ba94429SFrederic Weisbecker struct wq_device *wq_dev; 56306ba94429SFrederic Weisbecker int ret; 56316ba94429SFrederic Weisbecker 56326ba94429SFrederic Weisbecker /* 5633402dd89dSShailendra Verma * Adjusting max_active or creating new pwqs by applying 56346ba94429SFrederic Weisbecker * attributes breaks ordering guarantee. Disallow exposing ordered 56356ba94429SFrederic Weisbecker * workqueues. 56366ba94429SFrederic Weisbecker */ 56370a94efb5STejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT)) 56386ba94429SFrederic Weisbecker return -EINVAL; 56396ba94429SFrederic Weisbecker 56406ba94429SFrederic Weisbecker wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); 56416ba94429SFrederic Weisbecker if (!wq_dev) 56426ba94429SFrederic Weisbecker return -ENOMEM; 56436ba94429SFrederic Weisbecker 56446ba94429SFrederic Weisbecker wq_dev->wq = wq; 56456ba94429SFrederic Weisbecker wq_dev->dev.bus = &wq_subsys; 56466ba94429SFrederic Weisbecker wq_dev->dev.release = wq_device_release; 564723217b44SLars-Peter Clausen dev_set_name(&wq_dev->dev, "%s", wq->name); 56486ba94429SFrederic Weisbecker 56496ba94429SFrederic Weisbecker /* 56506ba94429SFrederic Weisbecker * unbound_attrs are created separately. Suppress uevent until 56516ba94429SFrederic Weisbecker * everything is ready. 56526ba94429SFrederic Weisbecker */ 56536ba94429SFrederic Weisbecker dev_set_uevent_suppress(&wq_dev->dev, true); 56546ba94429SFrederic Weisbecker 56556ba94429SFrederic Weisbecker ret = device_register(&wq_dev->dev); 56566ba94429SFrederic Weisbecker if (ret) { 5657537f4146SArvind Yadav put_device(&wq_dev->dev); 56586ba94429SFrederic Weisbecker wq->wq_dev = NULL; 56596ba94429SFrederic Weisbecker return ret; 56606ba94429SFrederic Weisbecker } 56616ba94429SFrederic Weisbecker 56626ba94429SFrederic Weisbecker if (wq->flags & WQ_UNBOUND) { 56636ba94429SFrederic Weisbecker struct device_attribute *attr; 56646ba94429SFrederic Weisbecker 56656ba94429SFrederic Weisbecker for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { 56666ba94429SFrederic Weisbecker ret = device_create_file(&wq_dev->dev, attr); 56676ba94429SFrederic Weisbecker if (ret) { 56686ba94429SFrederic Weisbecker device_unregister(&wq_dev->dev); 56696ba94429SFrederic Weisbecker wq->wq_dev = NULL; 56706ba94429SFrederic Weisbecker return ret; 56716ba94429SFrederic Weisbecker } 56726ba94429SFrederic Weisbecker } 56736ba94429SFrederic Weisbecker } 56746ba94429SFrederic Weisbecker 56756ba94429SFrederic Weisbecker dev_set_uevent_suppress(&wq_dev->dev, false); 56766ba94429SFrederic Weisbecker kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); 56776ba94429SFrederic Weisbecker return 0; 56786ba94429SFrederic Weisbecker } 56796ba94429SFrederic Weisbecker 56806ba94429SFrederic Weisbecker /** 56816ba94429SFrederic Weisbecker * workqueue_sysfs_unregister - undo workqueue_sysfs_register() 56826ba94429SFrederic Weisbecker * @wq: the workqueue to unregister 56836ba94429SFrederic Weisbecker * 56846ba94429SFrederic Weisbecker * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. 56856ba94429SFrederic Weisbecker */ 56866ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq) 56876ba94429SFrederic Weisbecker { 56886ba94429SFrederic Weisbecker struct wq_device *wq_dev = wq->wq_dev; 56896ba94429SFrederic Weisbecker 56906ba94429SFrederic Weisbecker if (!wq->wq_dev) 56916ba94429SFrederic Weisbecker return; 56926ba94429SFrederic Weisbecker 56936ba94429SFrederic Weisbecker wq->wq_dev = NULL; 56946ba94429SFrederic Weisbecker device_unregister(&wq_dev->dev); 56956ba94429SFrederic Weisbecker } 56966ba94429SFrederic Weisbecker #else /* CONFIG_SYSFS */ 56976ba94429SFrederic Weisbecker static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } 56986ba94429SFrederic Weisbecker #endif /* CONFIG_SYSFS */ 56996ba94429SFrederic Weisbecker 570082607adcSTejun Heo /* 570182607adcSTejun Heo * Workqueue watchdog. 570282607adcSTejun Heo * 570382607adcSTejun Heo * Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal 570482607adcSTejun Heo * flush dependency, a concurrency managed work item which stays RUNNING 570582607adcSTejun Heo * indefinitely. Workqueue stalls can be very difficult to debug as the 570682607adcSTejun Heo * usual warning mechanisms don't trigger and internal workqueue state is 570782607adcSTejun Heo * largely opaque. 570882607adcSTejun Heo * 570982607adcSTejun Heo * Workqueue watchdog monitors all worker pools periodically and dumps 571082607adcSTejun Heo * state if some pools failed to make forward progress for a while where 571182607adcSTejun Heo * forward progress is defined as the first item on ->worklist changing. 571282607adcSTejun Heo * 571382607adcSTejun Heo * This mechanism is controlled through the kernel parameter 571482607adcSTejun Heo * "workqueue.watchdog_thresh" which can be updated at runtime through the 571582607adcSTejun Heo * corresponding sysfs parameter file. 571682607adcSTejun Heo */ 571782607adcSTejun Heo #ifdef CONFIG_WQ_WATCHDOG 571882607adcSTejun Heo 571982607adcSTejun Heo static unsigned long wq_watchdog_thresh = 30; 57205cd79d6aSKees Cook static struct timer_list wq_watchdog_timer; 572182607adcSTejun Heo 572282607adcSTejun Heo static unsigned long wq_watchdog_touched = INITIAL_JIFFIES; 572382607adcSTejun Heo static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES; 572482607adcSTejun Heo 572582607adcSTejun Heo static void wq_watchdog_reset_touched(void) 572682607adcSTejun Heo { 572782607adcSTejun Heo int cpu; 572882607adcSTejun Heo 572982607adcSTejun Heo wq_watchdog_touched = jiffies; 573082607adcSTejun Heo for_each_possible_cpu(cpu) 573182607adcSTejun Heo per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; 573282607adcSTejun Heo } 573382607adcSTejun Heo 57345cd79d6aSKees Cook static void wq_watchdog_timer_fn(struct timer_list *unused) 573582607adcSTejun Heo { 573682607adcSTejun Heo unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ; 573782607adcSTejun Heo bool lockup_detected = false; 573882607adcSTejun Heo struct worker_pool *pool; 573982607adcSTejun Heo int pi; 574082607adcSTejun Heo 574182607adcSTejun Heo if (!thresh) 574282607adcSTejun Heo return; 574382607adcSTejun Heo 574482607adcSTejun Heo rcu_read_lock(); 574582607adcSTejun Heo 574682607adcSTejun Heo for_each_pool(pool, pi) { 574782607adcSTejun Heo unsigned long pool_ts, touched, ts; 574882607adcSTejun Heo 574982607adcSTejun Heo if (list_empty(&pool->worklist)) 575082607adcSTejun Heo continue; 575182607adcSTejun Heo 575282607adcSTejun Heo /* get the latest of pool and touched timestamps */ 575382607adcSTejun Heo pool_ts = READ_ONCE(pool->watchdog_ts); 575482607adcSTejun Heo touched = READ_ONCE(wq_watchdog_touched); 575582607adcSTejun Heo 575682607adcSTejun Heo if (time_after(pool_ts, touched)) 575782607adcSTejun Heo ts = pool_ts; 575882607adcSTejun Heo else 575982607adcSTejun Heo ts = touched; 576082607adcSTejun Heo 576182607adcSTejun Heo if (pool->cpu >= 0) { 576282607adcSTejun Heo unsigned long cpu_touched = 576382607adcSTejun Heo READ_ONCE(per_cpu(wq_watchdog_touched_cpu, 576482607adcSTejun Heo pool->cpu)); 576582607adcSTejun Heo if (time_after(cpu_touched, ts)) 576682607adcSTejun Heo ts = cpu_touched; 576782607adcSTejun Heo } 576882607adcSTejun Heo 576982607adcSTejun Heo /* did we stall? */ 577082607adcSTejun Heo if (time_after(jiffies, ts + thresh)) { 577182607adcSTejun Heo lockup_detected = true; 577282607adcSTejun Heo pr_emerg("BUG: workqueue lockup - pool"); 577382607adcSTejun Heo pr_cont_pool_info(pool); 577482607adcSTejun Heo pr_cont(" stuck for %us!\n", 577582607adcSTejun Heo jiffies_to_msecs(jiffies - pool_ts) / 1000); 577682607adcSTejun Heo } 577782607adcSTejun Heo } 577882607adcSTejun Heo 577982607adcSTejun Heo rcu_read_unlock(); 578082607adcSTejun Heo 578182607adcSTejun Heo if (lockup_detected) 578282607adcSTejun Heo show_workqueue_state(); 578382607adcSTejun Heo 578482607adcSTejun Heo wq_watchdog_reset_touched(); 578582607adcSTejun Heo mod_timer(&wq_watchdog_timer, jiffies + thresh); 578682607adcSTejun Heo } 578782607adcSTejun Heo 5788cb9d7fd5SVincent Whitchurch notrace void wq_watchdog_touch(int cpu) 578982607adcSTejun Heo { 579082607adcSTejun Heo if (cpu >= 0) 579182607adcSTejun Heo per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies; 579282607adcSTejun Heo else 579382607adcSTejun Heo wq_watchdog_touched = jiffies; 579482607adcSTejun Heo } 579582607adcSTejun Heo 579682607adcSTejun Heo static void wq_watchdog_set_thresh(unsigned long thresh) 579782607adcSTejun Heo { 579882607adcSTejun Heo wq_watchdog_thresh = 0; 579982607adcSTejun Heo del_timer_sync(&wq_watchdog_timer); 580082607adcSTejun Heo 580182607adcSTejun Heo if (thresh) { 580282607adcSTejun Heo wq_watchdog_thresh = thresh; 580382607adcSTejun Heo wq_watchdog_reset_touched(); 580482607adcSTejun Heo mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ); 580582607adcSTejun Heo } 580682607adcSTejun Heo } 580782607adcSTejun Heo 580882607adcSTejun Heo static int wq_watchdog_param_set_thresh(const char *val, 580982607adcSTejun Heo const struct kernel_param *kp) 581082607adcSTejun Heo { 581182607adcSTejun Heo unsigned long thresh; 581282607adcSTejun Heo int ret; 581382607adcSTejun Heo 581482607adcSTejun Heo ret = kstrtoul(val, 0, &thresh); 581582607adcSTejun Heo if (ret) 581682607adcSTejun Heo return ret; 581782607adcSTejun Heo 581882607adcSTejun Heo if (system_wq) 581982607adcSTejun Heo wq_watchdog_set_thresh(thresh); 582082607adcSTejun Heo else 582182607adcSTejun Heo wq_watchdog_thresh = thresh; 582282607adcSTejun Heo 582382607adcSTejun Heo return 0; 582482607adcSTejun Heo } 582582607adcSTejun Heo 582682607adcSTejun Heo static const struct kernel_param_ops wq_watchdog_thresh_ops = { 582782607adcSTejun Heo .set = wq_watchdog_param_set_thresh, 582882607adcSTejun Heo .get = param_get_ulong, 582982607adcSTejun Heo }; 583082607adcSTejun Heo 583182607adcSTejun Heo module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh, 583282607adcSTejun Heo 0644); 583382607adcSTejun Heo 583482607adcSTejun Heo static void wq_watchdog_init(void) 583582607adcSTejun Heo { 58365cd79d6aSKees Cook timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE); 583782607adcSTejun Heo wq_watchdog_set_thresh(wq_watchdog_thresh); 583882607adcSTejun Heo } 583982607adcSTejun Heo 584082607adcSTejun Heo #else /* CONFIG_WQ_WATCHDOG */ 584182607adcSTejun Heo 584282607adcSTejun Heo static inline void wq_watchdog_init(void) { } 584382607adcSTejun Heo 584482607adcSTejun Heo #endif /* CONFIG_WQ_WATCHDOG */ 584582607adcSTejun Heo 5846bce90380STejun Heo static void __init wq_numa_init(void) 5847bce90380STejun Heo { 5848bce90380STejun Heo cpumask_var_t *tbl; 5849bce90380STejun Heo int node, cpu; 5850bce90380STejun Heo 5851bce90380STejun Heo if (num_possible_nodes() <= 1) 5852bce90380STejun Heo return; 5853bce90380STejun Heo 5854d55262c4STejun Heo if (wq_disable_numa) { 5855d55262c4STejun Heo pr_info("workqueue: NUMA affinity support disabled\n"); 5856d55262c4STejun Heo return; 5857d55262c4STejun Heo } 5858d55262c4STejun Heo 5859be69d00dSThomas Gleixner wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(); 58604c16bd32STejun Heo BUG_ON(!wq_update_unbound_numa_attrs_buf); 58614c16bd32STejun Heo 5862bce90380STejun Heo /* 5863bce90380STejun Heo * We want masks of possible CPUs of each node which isn't readily 5864bce90380STejun Heo * available. Build one from cpu_to_node() which should have been 5865bce90380STejun Heo * fully initialized by now. 5866bce90380STejun Heo */ 58676396bb22SKees Cook tbl = kcalloc(nr_node_ids, sizeof(tbl[0]), GFP_KERNEL); 5868bce90380STejun Heo BUG_ON(!tbl); 5869bce90380STejun Heo 5870bce90380STejun Heo for_each_node(node) 58715a6024f1SYasuaki Ishimatsu BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL, 58721be0c25dSTejun Heo node_online(node) ? node : NUMA_NO_NODE)); 5873bce90380STejun Heo 5874bce90380STejun Heo for_each_possible_cpu(cpu) { 5875bce90380STejun Heo node = cpu_to_node(cpu); 5876bce90380STejun Heo if (WARN_ON(node == NUMA_NO_NODE)) { 5877bce90380STejun Heo pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); 5878bce90380STejun Heo /* happens iff arch is bonkers, let's just proceed */ 5879bce90380STejun Heo return; 5880bce90380STejun Heo } 5881bce90380STejun Heo cpumask_set_cpu(cpu, tbl[node]); 5882bce90380STejun Heo } 5883bce90380STejun Heo 5884bce90380STejun Heo wq_numa_possible_cpumask = tbl; 5885bce90380STejun Heo wq_numa_enabled = true; 5886bce90380STejun Heo } 5887bce90380STejun Heo 58883347fa09STejun Heo /** 58893347fa09STejun Heo * workqueue_init_early - early init for workqueue subsystem 58903347fa09STejun Heo * 58913347fa09STejun Heo * This is the first half of two-staged workqueue subsystem initialization 58923347fa09STejun Heo * and invoked as soon as the bare basics - memory allocation, cpumasks and 58933347fa09STejun Heo * idr are up. It sets up all the data structures and system workqueues 58943347fa09STejun Heo * and allows early boot code to create workqueues and queue/cancel work 58953347fa09STejun Heo * items. Actual work item execution starts only after kthreads can be 58963347fa09STejun Heo * created and scheduled right before early initcalls. 58973347fa09STejun Heo */ 58983347fa09STejun Heo int __init workqueue_init_early(void) 58991da177e4SLinus Torvalds { 59007a4e344cSTejun Heo int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; 59011bda3f80SFrederic Weisbecker int hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ; 59027a4e344cSTejun Heo int i, cpu; 5903c34056a3STejun Heo 5904e904e6c2STejun Heo WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); 5905e904e6c2STejun Heo 5906b05a7928SFrederic Weisbecker BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL)); 59071bda3f80SFrederic Weisbecker cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(hk_flags)); 5908b05a7928SFrederic Weisbecker 5909e904e6c2STejun Heo pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); 5910e904e6c2STejun Heo 5911706026c2STejun Heo /* initialize CPU pools */ 591229c91e99STejun Heo for_each_possible_cpu(cpu) { 59134ce62e9eSTejun Heo struct worker_pool *pool; 59148b03ae3cSTejun Heo 59157a4e344cSTejun Heo i = 0; 5916f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 59177a4e344cSTejun Heo BUG_ON(init_worker_pool(pool)); 5918ec22ca5eSTejun Heo pool->cpu = cpu; 59197a4e344cSTejun Heo cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); 59207a4e344cSTejun Heo pool->attrs->nice = std_nice[i++]; 5921f3f90ad4STejun Heo pool->node = cpu_to_node(cpu); 59227a4e344cSTejun Heo 59239daf9e67STejun Heo /* alloc pool ID */ 592468e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 59259daf9e67STejun Heo BUG_ON(worker_pool_assign_id(pool)); 592668e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 59274ce62e9eSTejun Heo } 59288b03ae3cSTejun Heo } 59298b03ae3cSTejun Heo 59308a2b7538STejun Heo /* create default unbound and ordered wq attrs */ 593129c91e99STejun Heo for (i = 0; i < NR_STD_WORKER_POOLS; i++) { 593229c91e99STejun Heo struct workqueue_attrs *attrs; 593329c91e99STejun Heo 5934be69d00dSThomas Gleixner BUG_ON(!(attrs = alloc_workqueue_attrs())); 593529c91e99STejun Heo attrs->nice = std_nice[i]; 593629c91e99STejun Heo unbound_std_wq_attrs[i] = attrs; 59378a2b7538STejun Heo 59388a2b7538STejun Heo /* 59398a2b7538STejun Heo * An ordered wq should have only one pwq as ordering is 59408a2b7538STejun Heo * guaranteed by max_active which is enforced by pwqs. 59418a2b7538STejun Heo * Turn off NUMA so that dfl_pwq is used for all nodes. 59428a2b7538STejun Heo */ 5943be69d00dSThomas Gleixner BUG_ON(!(attrs = alloc_workqueue_attrs())); 59448a2b7538STejun Heo attrs->nice = std_nice[i]; 59458a2b7538STejun Heo attrs->no_numa = true; 59468a2b7538STejun Heo ordered_wq_attrs[i] = attrs; 594729c91e99STejun Heo } 594829c91e99STejun Heo 5949d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 59501aabe902SJoonsoo Kim system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 5951d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 5952f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 5953f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 595424d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 595524d51addSTejun Heo WQ_FREEZABLE, 0); 59560668106cSViresh Kumar system_power_efficient_wq = alloc_workqueue("events_power_efficient", 59570668106cSViresh Kumar WQ_POWER_EFFICIENT, 0); 59580668106cSViresh Kumar system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", 59590668106cSViresh Kumar WQ_FREEZABLE | WQ_POWER_EFFICIENT, 59600668106cSViresh Kumar 0); 59611aabe902SJoonsoo Kim BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 59620668106cSViresh Kumar !system_unbound_wq || !system_freezable_wq || 59630668106cSViresh Kumar !system_power_efficient_wq || 59640668106cSViresh Kumar !system_freezable_power_efficient_wq); 596582607adcSTejun Heo 59663347fa09STejun Heo return 0; 59673347fa09STejun Heo } 59683347fa09STejun Heo 59693347fa09STejun Heo /** 59703347fa09STejun Heo * workqueue_init - bring workqueue subsystem fully online 59713347fa09STejun Heo * 59723347fa09STejun Heo * This is the latter half of two-staged workqueue subsystem initialization 59733347fa09STejun Heo * and invoked as soon as kthreads can be created and scheduled. 59743347fa09STejun Heo * Workqueues have been created and work items queued on them, but there 59753347fa09STejun Heo * are no kworkers executing the work items yet. Populate the worker pools 59763347fa09STejun Heo * with the initial workers and enable future kworker creations. 59773347fa09STejun Heo */ 59783347fa09STejun Heo int __init workqueue_init(void) 59793347fa09STejun Heo { 59802186d9f9STejun Heo struct workqueue_struct *wq; 59813347fa09STejun Heo struct worker_pool *pool; 59823347fa09STejun Heo int cpu, bkt; 59833347fa09STejun Heo 59842186d9f9STejun Heo /* 59852186d9f9STejun Heo * It'd be simpler to initialize NUMA in workqueue_init_early() but 59862186d9f9STejun Heo * CPU to node mapping may not be available that early on some 59872186d9f9STejun Heo * archs such as power and arm64. As per-cpu pools created 59882186d9f9STejun Heo * previously could be missing node hint and unbound pools NUMA 59892186d9f9STejun Heo * affinity, fix them up. 599040c17f75STejun Heo * 599140c17f75STejun Heo * Also, while iterating workqueues, create rescuers if requested. 59922186d9f9STejun Heo */ 59932186d9f9STejun Heo wq_numa_init(); 59942186d9f9STejun Heo 59952186d9f9STejun Heo mutex_lock(&wq_pool_mutex); 59962186d9f9STejun Heo 59972186d9f9STejun Heo for_each_possible_cpu(cpu) { 59982186d9f9STejun Heo for_each_cpu_worker_pool(pool, cpu) { 59992186d9f9STejun Heo pool->node = cpu_to_node(cpu); 60002186d9f9STejun Heo } 60012186d9f9STejun Heo } 60022186d9f9STejun Heo 600340c17f75STejun Heo list_for_each_entry(wq, &workqueues, list) { 60042186d9f9STejun Heo wq_update_unbound_numa(wq, smp_processor_id(), true); 600540c17f75STejun Heo WARN(init_rescuer(wq), 600640c17f75STejun Heo "workqueue: failed to create early rescuer for %s", 600740c17f75STejun Heo wq->name); 600840c17f75STejun Heo } 60092186d9f9STejun Heo 60102186d9f9STejun Heo mutex_unlock(&wq_pool_mutex); 60112186d9f9STejun Heo 60123347fa09STejun Heo /* create the initial workers */ 60133347fa09STejun Heo for_each_online_cpu(cpu) { 60143347fa09STejun Heo for_each_cpu_worker_pool(pool, cpu) { 60153347fa09STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 60163347fa09STejun Heo BUG_ON(!create_worker(pool)); 60173347fa09STejun Heo } 60183347fa09STejun Heo } 60193347fa09STejun Heo 60203347fa09STejun Heo hash_for_each(unbound_pool_hash, bkt, pool, hash_node) 60213347fa09STejun Heo BUG_ON(!create_worker(pool)); 60223347fa09STejun Heo 60233347fa09STejun Heo wq_online = true; 602482607adcSTejun Heo wq_watchdog_init(); 602582607adcSTejun Heo 60266ee0578bSSuresh Siddha return 0; 60271da177e4SLinus Torvalds } 6028