11da177e4SLinus Torvalds /* 2c54fce6eSTejun Heo * kernel/workqueue.c - generic async execution with shared worker pool 31da177e4SLinus Torvalds * 4c54fce6eSTejun Heo * Copyright (C) 2002 Ingo Molnar 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Derived from the taskqueue/keventd code by: 71da177e4SLinus Torvalds * David Woodhouse <dwmw2@infradead.org> 8e1f8e874SFrancois Cami * Andrew Morton 91da177e4SLinus Torvalds * Kai Petzke <wpp@marie.physik.tu-berlin.de> 101da177e4SLinus Torvalds * Theodore Ts'o <tytso@mit.edu> 1189ada679SChristoph Lameter * 12cde53535SChristoph Lameter * Made to use alloc_percpu by Christoph Lameter. 13c54fce6eSTejun Heo * 14c54fce6eSTejun Heo * Copyright (C) 2010 SUSE Linux Products GmbH 15c54fce6eSTejun Heo * Copyright (C) 2010 Tejun Heo <tj@kernel.org> 16c54fce6eSTejun Heo * 17c54fce6eSTejun Heo * This is the generic async execution mechanism. Work items as are 18c54fce6eSTejun Heo * executed in process context. The worker pool is shared and 19c54fce6eSTejun Heo * automatically managed. There is one worker pool for each CPU and 20c54fce6eSTejun Heo * one extra for works which are better served by workers which are 21c54fce6eSTejun Heo * not bound to any specific CPU. 22c54fce6eSTejun Heo * 23c54fce6eSTejun Heo * Please read Documentation/workqueue.txt for details. 241da177e4SLinus Torvalds */ 251da177e4SLinus Torvalds 269984de1aSPaul Gortmaker #include <linux/export.h> 271da177e4SLinus Torvalds #include <linux/kernel.h> 281da177e4SLinus Torvalds #include <linux/sched.h> 291da177e4SLinus Torvalds #include <linux/init.h> 301da177e4SLinus Torvalds #include <linux/signal.h> 311da177e4SLinus Torvalds #include <linux/completion.h> 321da177e4SLinus Torvalds #include <linux/workqueue.h> 331da177e4SLinus Torvalds #include <linux/slab.h> 341da177e4SLinus Torvalds #include <linux/cpu.h> 351da177e4SLinus Torvalds #include <linux/notifier.h> 361da177e4SLinus Torvalds #include <linux/kthread.h> 371fa44ecaSJames Bottomley #include <linux/hardirq.h> 3846934023SChristoph Lameter #include <linux/mempolicy.h> 39341a5958SRafael J. Wysocki #include <linux/freezer.h> 40d5abe669SPeter Zijlstra #include <linux/kallsyms.h> 41d5abe669SPeter Zijlstra #include <linux/debug_locks.h> 424e6045f1SJohannes Berg #include <linux/lockdep.h> 43c34056a3STejun Heo #include <linux/idr.h> 4442f8570fSSasha Levin #include <linux/hashtable.h> 45e22bee78STejun Heo 46ea138446STejun Heo #include "workqueue_internal.h" 471da177e4SLinus Torvalds 48c8e55f36STejun Heo enum { 49bc2ae0f5STejun Heo /* 5024647570STejun Heo * worker_pool flags 51bc2ae0f5STejun Heo * 5224647570STejun Heo * A bound pool is either associated or disassociated with its CPU. 53bc2ae0f5STejun Heo * While associated (!DISASSOCIATED), all workers are bound to the 54bc2ae0f5STejun Heo * CPU and none has %WORKER_UNBOUND set and concurrency management 55bc2ae0f5STejun Heo * is in effect. 56bc2ae0f5STejun Heo * 57bc2ae0f5STejun Heo * While DISASSOCIATED, the cpu may be offline and all workers have 58bc2ae0f5STejun Heo * %WORKER_UNBOUND set and concurrency management disabled, and may 5924647570STejun Heo * be executing on any CPU. The pool behaves as an unbound one. 60bc2ae0f5STejun Heo * 61bc2ae0f5STejun Heo * Note that DISASSOCIATED can be flipped only while holding 6224647570STejun Heo * assoc_mutex to avoid changing binding state while 6324647570STejun Heo * create_worker() is in progress. 64bc2ae0f5STejun Heo */ 6511ebea50STejun Heo POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ 66552a37e9SLai Jiangshan POOL_MANAGING_WORKERS = 1 << 1, /* managing workers */ 6724647570STejun Heo POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 6835b6bb63STejun Heo POOL_FREEZING = 1 << 3, /* freeze in progress */ 69db7bccf4STejun Heo 70c8e55f36STejun Heo /* worker flags */ 71c8e55f36STejun Heo WORKER_STARTED = 1 << 0, /* started */ 72c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 73c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 74e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 75fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 76f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 77e22bee78STejun Heo 785f7dabfdSLai Jiangshan WORKER_NOT_RUNNING = WORKER_PREP | WORKER_UNBOUND | 79403c821dSTejun Heo WORKER_CPU_INTENSIVE, 80db7bccf4STejun Heo 81e34cdddbSTejun Heo NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ 824ce62e9eSTejun Heo 83c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 84db7bccf4STejun Heo 85e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 86e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 87e22bee78STejun Heo 883233cdbdSTejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, 893233cdbdSTejun Heo /* call for help after 10ms 903233cdbdSTejun Heo (min two ticks) */ 91e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 92e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* 95e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 96e22bee78STejun Heo * all cpus. Give -20. 97e22bee78STejun Heo */ 98e22bee78STejun Heo RESCUER_NICE_LEVEL = -20, 993270476aSTejun Heo HIGHPRI_NICE_LEVEL = -20, 100c8e55f36STejun Heo }; 101c8e55f36STejun Heo 1021da177e4SLinus Torvalds /* 1034690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 1044690c4abSTejun Heo * 105e41e704bSTejun Heo * I: Modifiable by initialization/destruction paths and read-only for 106e41e704bSTejun Heo * everyone else. 1074690c4abSTejun Heo * 108e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 109e22bee78STejun Heo * only be modified and accessed from the local cpu. 110e22bee78STejun Heo * 111d565ed63STejun Heo * L: pool->lock protected. Access with pool->lock held. 1124690c4abSTejun Heo * 113d565ed63STejun Heo * X: During normal operation, modification requires pool->lock and should 114d565ed63STejun Heo * be done only from local cpu. Either disabling preemption on local 115d565ed63STejun Heo * cpu or grabbing pool->lock is enough for read access. If 116d565ed63STejun Heo * POOL_DISASSOCIATED is set, it's identical to L. 117e22bee78STejun Heo * 11873f53c4aSTejun Heo * F: wq->flush_mutex protected. 11973f53c4aSTejun Heo * 1204690c4abSTejun Heo * W: workqueue_lock protected. 1214690c4abSTejun Heo */ 1224690c4abSTejun Heo 1232eaebdb3STejun Heo /* struct worker is defined in workqueue_internal.h */ 124c34056a3STejun Heo 125bd7bdd43STejun Heo struct worker_pool { 126d565ed63STejun Heo spinlock_t lock; /* the pool lock */ 127d84ff051STejun Heo int cpu; /* I: the associated cpu */ 1289daf9e67STejun Heo int id; /* I: pool ID */ 12911ebea50STejun Heo unsigned int flags; /* X: flags */ 130bd7bdd43STejun Heo 131bd7bdd43STejun Heo struct list_head worklist; /* L: list of pending works */ 132bd7bdd43STejun Heo int nr_workers; /* L: total number of workers */ 133ea1abd61SLai Jiangshan 134ea1abd61SLai Jiangshan /* nr_idle includes the ones off idle_list for rebinding */ 135bd7bdd43STejun Heo int nr_idle; /* L: currently idle ones */ 136bd7bdd43STejun Heo 137bd7bdd43STejun Heo struct list_head idle_list; /* X: list of idle workers */ 138bd7bdd43STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 139bd7bdd43STejun Heo struct timer_list mayday_timer; /* L: SOS timer for workers */ 140bd7bdd43STejun Heo 141c9e7cf27STejun Heo /* workers are chained either in busy_hash or idle_list */ 142c9e7cf27STejun Heo DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); 143c9e7cf27STejun Heo /* L: hash of busy workers */ 144c9e7cf27STejun Heo 14524647570STejun Heo struct mutex assoc_mutex; /* protect POOL_DISASSOCIATED */ 146bd7bdd43STejun Heo struct ida worker_ida; /* L: for worker IDs */ 147e19e397aSTejun Heo 148e19e397aSTejun Heo /* 149e19e397aSTejun Heo * The current concurrency level. As it's likely to be accessed 150e19e397aSTejun Heo * from other CPUs during try_to_wake_up(), put it in a separate 151e19e397aSTejun Heo * cacheline. 152e19e397aSTejun Heo */ 153e19e397aSTejun Heo atomic_t nr_running ____cacheline_aligned_in_smp; 1548b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1558b03ae3cSTejun Heo 1568b03ae3cSTejun Heo /* 157112202d9STejun Heo * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS 158112202d9STejun Heo * of work_struct->data are used for flags and the remaining high bits 159112202d9STejun Heo * point to the pwq; thus, pwqs need to be aligned at two's power of the 160112202d9STejun Heo * number of flag bits. 1611da177e4SLinus Torvalds */ 162112202d9STejun Heo struct pool_workqueue { 163bd7bdd43STejun Heo struct worker_pool *pool; /* I: the associated pool */ 1644690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 16573f53c4aSTejun Heo int work_color; /* L: current color */ 16673f53c4aSTejun Heo int flush_color; /* L: flushing color */ 16773f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 16873f53c4aSTejun Heo /* L: nr of in_flight works */ 1691e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 170a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 1711e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 17230cdf249STejun Heo struct list_head pwqs_node; /* I: node on wq->pwqs */ 173493a1724STejun Heo struct list_head mayday_node; /* W: node on wq->maydays */ 174e904e6c2STejun Heo } __aligned(1 << WORK_STRUCT_FLAG_BITS); 1751da177e4SLinus Torvalds 1761da177e4SLinus Torvalds /* 17773f53c4aSTejun Heo * Structure used to wait for workqueue flush. 17873f53c4aSTejun Heo */ 17973f53c4aSTejun Heo struct wq_flusher { 18073f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 18173f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 18273f53c4aSTejun Heo struct completion done; /* flush completion */ 18373f53c4aSTejun Heo }; 1841da177e4SLinus Torvalds 18573f53c4aSTejun Heo /* 1861da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 1871da177e4SLinus Torvalds * per-CPU workqueues: 1881da177e4SLinus Torvalds */ 1891da177e4SLinus Torvalds struct workqueue_struct { 1909c5a2ba7STejun Heo unsigned int flags; /* W: WQ_* flags */ 191bdbc5dd7STejun Heo union { 192112202d9STejun Heo struct pool_workqueue __percpu *pcpu; 193112202d9STejun Heo struct pool_workqueue *single; 194bdbc5dd7STejun Heo unsigned long v; 195112202d9STejun Heo } pool_wq; /* I: pwq's */ 19630cdf249STejun Heo struct list_head pwqs; /* I: all pwqs of this wq */ 1974690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 19873f53c4aSTejun Heo 19973f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 20073f53c4aSTejun Heo int work_color; /* F: current work color */ 20173f53c4aSTejun Heo int flush_color; /* F: current flush color */ 202112202d9STejun Heo atomic_t nr_pwqs_to_flush; /* flush in progress */ 20373f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 20473f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 20573f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 20673f53c4aSTejun Heo 207493a1724STejun Heo struct list_head maydays; /* W: pwqs requesting rescue */ 208e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 209e22bee78STejun Heo 2109c5a2ba7STejun Heo int nr_drainers; /* W: drain in progress */ 211112202d9STejun Heo int saved_max_active; /* W: saved pwq max_active */ 2124e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2134e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2144e6045f1SJohannes Berg #endif 215b196be89STejun Heo char name[]; /* I: workqueue name */ 2161da177e4SLinus Torvalds }; 2171da177e4SLinus Torvalds 218e904e6c2STejun Heo static struct kmem_cache *pwq_cache; 219e904e6c2STejun Heo 220d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 221d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 222044c782cSValentin Ilie struct workqueue_struct *system_highpri_wq __read_mostly; 2231aabe902SJoonsoo Kim EXPORT_SYMBOL_GPL(system_highpri_wq); 224044c782cSValentin Ilie struct workqueue_struct *system_long_wq __read_mostly; 225d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 226044c782cSValentin Ilie struct workqueue_struct *system_unbound_wq __read_mostly; 227f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 228044c782cSValentin Ilie struct workqueue_struct *system_freezable_wq __read_mostly; 22924d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 230d320c038STejun Heo 23197bd2347STejun Heo #define CREATE_TRACE_POINTS 23297bd2347STejun Heo #include <trace/events/workqueue.h> 23397bd2347STejun Heo 23438db41d9STejun Heo #define for_each_std_worker_pool(pool, cpu) \ 235a60dc39cSTejun Heo for ((pool) = &std_worker_pools(cpu)[0]; \ 236a60dc39cSTejun Heo (pool) < &std_worker_pools(cpu)[NR_STD_WORKER_POOLS]; (pool)++) 2374ce62e9eSTejun Heo 238b67bfe0dSSasha Levin #define for_each_busy_worker(worker, i, pool) \ 239b67bfe0dSSasha Levin hash_for_each(pool->busy_hash, i, worker, hentry) 240db7bccf4STejun Heo 241706026c2STejun Heo static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, 242f3421797STejun Heo unsigned int sw) 243f3421797STejun Heo { 244f3421797STejun Heo if (cpu < nr_cpu_ids) { 245f3421797STejun Heo if (sw & 1) { 246f3421797STejun Heo cpu = cpumask_next(cpu, mask); 247f3421797STejun Heo if (cpu < nr_cpu_ids) 248f3421797STejun Heo return cpu; 249f3421797STejun Heo } 250f3421797STejun Heo if (sw & 2) 251f3421797STejun Heo return WORK_CPU_UNBOUND; 252f3421797STejun Heo } 2536be19588SLai Jiangshan return WORK_CPU_END; 254f3421797STejun Heo } 255f3421797STejun Heo 25609884951STejun Heo /* 25709884951STejun Heo * CPU iterators 25809884951STejun Heo * 259706026c2STejun Heo * An extra cpu number is defined using an invalid cpu number 26009884951STejun Heo * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any 261706026c2STejun Heo * specific CPU. The following iterators are similar to for_each_*_cpu() 262706026c2STejun Heo * iterators but also considers the unbound CPU. 26309884951STejun Heo * 264706026c2STejun Heo * for_each_wq_cpu() : possible CPUs + WORK_CPU_UNBOUND 265706026c2STejun Heo * for_each_online_wq_cpu() : online CPUs + WORK_CPU_UNBOUND 26609884951STejun Heo */ 267706026c2STejun Heo #define for_each_wq_cpu(cpu) \ 268706026c2STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, 3); \ 2696be19588SLai Jiangshan (cpu) < WORK_CPU_END; \ 270706026c2STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, 3)) 271f3421797STejun Heo 272706026c2STejun Heo #define for_each_online_wq_cpu(cpu) \ 273706026c2STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_online_mask, 3); \ 2746be19588SLai Jiangshan (cpu) < WORK_CPU_END; \ 275706026c2STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_online_mask, 3)) 276f3421797STejun Heo 27749e3cf44STejun Heo /** 27817116969STejun Heo * for_each_pool - iterate through all worker_pools in the system 27917116969STejun Heo * @pool: iteration cursor 28017116969STejun Heo * @id: integer used for iteration 28117116969STejun Heo */ 28217116969STejun Heo #define for_each_pool(pool, id) \ 28317116969STejun Heo idr_for_each_entry(&worker_pool_idr, pool, id) 28417116969STejun Heo 28517116969STejun Heo /** 28649e3cf44STejun Heo * for_each_pwq - iterate through all pool_workqueues of the specified workqueue 28749e3cf44STejun Heo * @pwq: iteration cursor 28849e3cf44STejun Heo * @wq: the target workqueue 28949e3cf44STejun Heo */ 29049e3cf44STejun Heo #define for_each_pwq(pwq, wq) \ 29149e3cf44STejun Heo list_for_each_entry((pwq), &(wq)->pwqs, pwqs_node) 292f3421797STejun Heo 293dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 294dc186ad7SThomas Gleixner 295dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 296dc186ad7SThomas Gleixner 29799777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 29899777288SStanislaw Gruszka { 29999777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 30099777288SStanislaw Gruszka } 30199777288SStanislaw Gruszka 302dc186ad7SThomas Gleixner /* 303dc186ad7SThomas Gleixner * fixup_init is called when: 304dc186ad7SThomas Gleixner * - an active object is initialized 305dc186ad7SThomas Gleixner */ 306dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 307dc186ad7SThomas Gleixner { 308dc186ad7SThomas Gleixner struct work_struct *work = addr; 309dc186ad7SThomas Gleixner 310dc186ad7SThomas Gleixner switch (state) { 311dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 312dc186ad7SThomas Gleixner cancel_work_sync(work); 313dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 314dc186ad7SThomas Gleixner return 1; 315dc186ad7SThomas Gleixner default: 316dc186ad7SThomas Gleixner return 0; 317dc186ad7SThomas Gleixner } 318dc186ad7SThomas Gleixner } 319dc186ad7SThomas Gleixner 320dc186ad7SThomas Gleixner /* 321dc186ad7SThomas Gleixner * fixup_activate is called when: 322dc186ad7SThomas Gleixner * - an active object is activated 323dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 324dc186ad7SThomas Gleixner */ 325dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 326dc186ad7SThomas Gleixner { 327dc186ad7SThomas Gleixner struct work_struct *work = addr; 328dc186ad7SThomas Gleixner 329dc186ad7SThomas Gleixner switch (state) { 330dc186ad7SThomas Gleixner 331dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 332dc186ad7SThomas Gleixner /* 333dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 334dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 335dc186ad7SThomas Gleixner * is tracked in the object tracker. 336dc186ad7SThomas Gleixner */ 33722df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 338dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 339dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 340dc186ad7SThomas Gleixner return 0; 341dc186ad7SThomas Gleixner } 342dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 343dc186ad7SThomas Gleixner return 0; 344dc186ad7SThomas Gleixner 345dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 346dc186ad7SThomas Gleixner WARN_ON(1); 347dc186ad7SThomas Gleixner 348dc186ad7SThomas Gleixner default: 349dc186ad7SThomas Gleixner return 0; 350dc186ad7SThomas Gleixner } 351dc186ad7SThomas Gleixner } 352dc186ad7SThomas Gleixner 353dc186ad7SThomas Gleixner /* 354dc186ad7SThomas Gleixner * fixup_free is called when: 355dc186ad7SThomas Gleixner * - an active object is freed 356dc186ad7SThomas Gleixner */ 357dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 358dc186ad7SThomas Gleixner { 359dc186ad7SThomas Gleixner struct work_struct *work = addr; 360dc186ad7SThomas Gleixner 361dc186ad7SThomas Gleixner switch (state) { 362dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 363dc186ad7SThomas Gleixner cancel_work_sync(work); 364dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 365dc186ad7SThomas Gleixner return 1; 366dc186ad7SThomas Gleixner default: 367dc186ad7SThomas Gleixner return 0; 368dc186ad7SThomas Gleixner } 369dc186ad7SThomas Gleixner } 370dc186ad7SThomas Gleixner 371dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 372dc186ad7SThomas Gleixner .name = "work_struct", 37399777288SStanislaw Gruszka .debug_hint = work_debug_hint, 374dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 375dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 376dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 377dc186ad7SThomas Gleixner }; 378dc186ad7SThomas Gleixner 379dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 380dc186ad7SThomas Gleixner { 381dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 382dc186ad7SThomas Gleixner } 383dc186ad7SThomas Gleixner 384dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 385dc186ad7SThomas Gleixner { 386dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 387dc186ad7SThomas Gleixner } 388dc186ad7SThomas Gleixner 389dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 390dc186ad7SThomas Gleixner { 391dc186ad7SThomas Gleixner if (onstack) 392dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 393dc186ad7SThomas Gleixner else 394dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 395dc186ad7SThomas Gleixner } 396dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 397dc186ad7SThomas Gleixner 398dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 399dc186ad7SThomas Gleixner { 400dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 401dc186ad7SThomas Gleixner } 402dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 403dc186ad7SThomas Gleixner 404dc186ad7SThomas Gleixner #else 405dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 406dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 407dc186ad7SThomas Gleixner #endif 408dc186ad7SThomas Gleixner 40995402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 41095402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 4111da177e4SLinus Torvalds static LIST_HEAD(workqueues); 412a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 4131da177e4SLinus Torvalds 41414441960SOleg Nesterov /* 415e19e397aSTejun Heo * The CPU and unbound standard worker pools. The unbound ones have 416e19e397aSTejun Heo * POOL_DISASSOCIATED set, and their workers have WORKER_UNBOUND set. 41714441960SOleg Nesterov */ 418e19e397aSTejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], 419a60dc39cSTejun Heo cpu_std_worker_pools); 420a60dc39cSTejun Heo static struct worker_pool unbound_std_worker_pools[NR_STD_WORKER_POOLS]; 421f3421797STejun Heo 4229daf9e67STejun Heo /* idr of all pools */ 4239daf9e67STejun Heo static DEFINE_MUTEX(worker_pool_idr_mutex); 4249daf9e67STejun Heo static DEFINE_IDR(worker_pool_idr); 4259daf9e67STejun Heo 426c34056a3STejun Heo static int worker_thread(void *__worker); 4271da177e4SLinus Torvalds 428a60dc39cSTejun Heo static struct worker_pool *std_worker_pools(int cpu) 4291da177e4SLinus Torvalds { 430f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 431a60dc39cSTejun Heo return per_cpu(cpu_std_worker_pools, cpu); 432f3421797STejun Heo else 433a60dc39cSTejun Heo return unbound_std_worker_pools; 4341da177e4SLinus Torvalds } 4351da177e4SLinus Torvalds 4364e8f0a60STejun Heo static int std_worker_pool_pri(struct worker_pool *pool) 4374e8f0a60STejun Heo { 438a60dc39cSTejun Heo return pool - std_worker_pools(pool->cpu); 4394e8f0a60STejun Heo } 4404e8f0a60STejun Heo 4419daf9e67STejun Heo /* allocate ID and assign it to @pool */ 4429daf9e67STejun Heo static int worker_pool_assign_id(struct worker_pool *pool) 4439daf9e67STejun Heo { 4449daf9e67STejun Heo int ret; 4459daf9e67STejun Heo 4469daf9e67STejun Heo mutex_lock(&worker_pool_idr_mutex); 4479daf9e67STejun Heo idr_pre_get(&worker_pool_idr, GFP_KERNEL); 4489daf9e67STejun Heo ret = idr_get_new(&worker_pool_idr, pool, &pool->id); 4499daf9e67STejun Heo mutex_unlock(&worker_pool_idr_mutex); 4509daf9e67STejun Heo 4519daf9e67STejun Heo return ret; 4529daf9e67STejun Heo } 4539daf9e67STejun Heo 4547c3eed5cSTejun Heo /* 4557c3eed5cSTejun Heo * Lookup worker_pool by id. The idr currently is built during boot and 4567c3eed5cSTejun Heo * never modified. Don't worry about locking for now. 4577c3eed5cSTejun Heo */ 4587c3eed5cSTejun Heo static struct worker_pool *worker_pool_by_id(int pool_id) 4597c3eed5cSTejun Heo { 4607c3eed5cSTejun Heo return idr_find(&worker_pool_idr, pool_id); 4617c3eed5cSTejun Heo } 4627c3eed5cSTejun Heo 463d565ed63STejun Heo static struct worker_pool *get_std_worker_pool(int cpu, bool highpri) 464d565ed63STejun Heo { 465a60dc39cSTejun Heo struct worker_pool *pools = std_worker_pools(cpu); 466d565ed63STejun Heo 467a60dc39cSTejun Heo return &pools[highpri]; 468d565ed63STejun Heo } 469d565ed63STejun Heo 470d84ff051STejun Heo static struct pool_workqueue *get_pwq(int cpu, struct workqueue_struct *wq) 471a848e3b6SOleg Nesterov { 472f3421797STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 473e06ffa1eSLai Jiangshan if (likely(cpu < nr_cpu_ids)) 474112202d9STejun Heo return per_cpu_ptr(wq->pool_wq.pcpu, cpu); 475f3421797STejun Heo } else if (likely(cpu == WORK_CPU_UNBOUND)) 476112202d9STejun Heo return wq->pool_wq.single; 477f3421797STejun Heo return NULL; 478f3421797STejun Heo } 479a848e3b6SOleg Nesterov 48073f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 48173f53c4aSTejun Heo { 48273f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 48373f53c4aSTejun Heo } 48473f53c4aSTejun Heo 48573f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 48673f53c4aSTejun Heo { 48773f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 48873f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 48973f53c4aSTejun Heo } 49073f53c4aSTejun Heo 49173f53c4aSTejun Heo static int work_next_color(int color) 49273f53c4aSTejun Heo { 49373f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 494b1f4ec17SOleg Nesterov } 495b1f4ec17SOleg Nesterov 4964594bf15SDavid Howells /* 497112202d9STejun Heo * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data 498112202d9STejun Heo * contain the pointer to the queued pwq. Once execution starts, the flag 4997c3eed5cSTejun Heo * is cleared and the high bits contain OFFQ flags and pool ID. 5007a22ad75STejun Heo * 501112202d9STejun Heo * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() 502112202d9STejun Heo * and clear_work_data() can be used to set the pwq, pool or clear 503bbb68dfaSTejun Heo * work->data. These functions should only be called while the work is 504bbb68dfaSTejun Heo * owned - ie. while the PENDING bit is set. 5057a22ad75STejun Heo * 506112202d9STejun Heo * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq 5077c3eed5cSTejun Heo * corresponding to a work. Pool is available once the work has been 508112202d9STejun Heo * queued anywhere after initialization until it is sync canceled. pwq is 5097c3eed5cSTejun Heo * available only while the work item is queued. 510bbb68dfaSTejun Heo * 511bbb68dfaSTejun Heo * %WORK_OFFQ_CANCELING is used to mark a work item which is being 512bbb68dfaSTejun Heo * canceled. While being canceled, a work item may have its PENDING set 513bbb68dfaSTejun Heo * but stay off timer and worklist for arbitrarily long and nobody should 514bbb68dfaSTejun Heo * try to steal the PENDING bit. 5154594bf15SDavid Howells */ 5167a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 5177a22ad75STejun Heo unsigned long flags) 5187a22ad75STejun Heo { 5196183c009STejun Heo WARN_ON_ONCE(!work_pending(work)); 5207a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 5217a22ad75STejun Heo } 5227a22ad75STejun Heo 523112202d9STejun Heo static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, 5244690c4abSTejun Heo unsigned long extra_flags) 525365970a1SDavid Howells { 526112202d9STejun Heo set_work_data(work, (unsigned long)pwq, 527112202d9STejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); 528365970a1SDavid Howells } 529365970a1SDavid Howells 5304468a00fSLai Jiangshan static void set_work_pool_and_keep_pending(struct work_struct *work, 5314468a00fSLai Jiangshan int pool_id) 5324468a00fSLai Jiangshan { 5334468a00fSLai Jiangshan set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 5344468a00fSLai Jiangshan WORK_STRUCT_PENDING); 5354468a00fSLai Jiangshan } 5364468a00fSLai Jiangshan 5377c3eed5cSTejun Heo static void set_work_pool_and_clear_pending(struct work_struct *work, 5387c3eed5cSTejun Heo int pool_id) 5394d707b9fSOleg Nesterov { 54023657bb1STejun Heo /* 54123657bb1STejun Heo * The following wmb is paired with the implied mb in 54223657bb1STejun Heo * test_and_set_bit(PENDING) and ensures all updates to @work made 54323657bb1STejun Heo * here are visible to and precede any updates by the next PENDING 54423657bb1STejun Heo * owner. 54523657bb1STejun Heo */ 54623657bb1STejun Heo smp_wmb(); 5477c3eed5cSTejun Heo set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); 5484d707b9fSOleg Nesterov } 5494d707b9fSOleg Nesterov 5507a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 551365970a1SDavid Howells { 5527c3eed5cSTejun Heo smp_wmb(); /* see set_work_pool_and_clear_pending() */ 5537c3eed5cSTejun Heo set_work_data(work, WORK_STRUCT_NO_POOL, 0); 5547a22ad75STejun Heo } 5557a22ad75STejun Heo 556112202d9STejun Heo static struct pool_workqueue *get_work_pwq(struct work_struct *work) 5577a22ad75STejun Heo { 558e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5597a22ad75STejun Heo 560112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 561e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 562e120153dSTejun Heo else 563e120153dSTejun Heo return NULL; 5647a22ad75STejun Heo } 5657a22ad75STejun Heo 5667c3eed5cSTejun Heo /** 5677c3eed5cSTejun Heo * get_work_pool - return the worker_pool a given work was associated with 5687c3eed5cSTejun Heo * @work: the work item of interest 5697c3eed5cSTejun Heo * 5707c3eed5cSTejun Heo * Return the worker_pool @work was last associated with. %NULL if none. 5717c3eed5cSTejun Heo */ 5727c3eed5cSTejun Heo static struct worker_pool *get_work_pool(struct work_struct *work) 5737a22ad75STejun Heo { 574e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5757c3eed5cSTejun Heo struct worker_pool *pool; 5767c3eed5cSTejun Heo int pool_id; 5777a22ad75STejun Heo 578112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 579112202d9STejun Heo return ((struct pool_workqueue *) 5807c3eed5cSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->pool; 5817a22ad75STejun Heo 5827c3eed5cSTejun Heo pool_id = data >> WORK_OFFQ_POOL_SHIFT; 5837c3eed5cSTejun Heo if (pool_id == WORK_OFFQ_POOL_NONE) 5847a22ad75STejun Heo return NULL; 5857a22ad75STejun Heo 5867c3eed5cSTejun Heo pool = worker_pool_by_id(pool_id); 5877c3eed5cSTejun Heo WARN_ON_ONCE(!pool); 5887c3eed5cSTejun Heo return pool; 5897c3eed5cSTejun Heo } 5907c3eed5cSTejun Heo 5917c3eed5cSTejun Heo /** 5927c3eed5cSTejun Heo * get_work_pool_id - return the worker pool ID a given work is associated with 5937c3eed5cSTejun Heo * @work: the work item of interest 5947c3eed5cSTejun Heo * 5957c3eed5cSTejun Heo * Return the worker_pool ID @work was last associated with. 5967c3eed5cSTejun Heo * %WORK_OFFQ_POOL_NONE if none. 5977c3eed5cSTejun Heo */ 5987c3eed5cSTejun Heo static int get_work_pool_id(struct work_struct *work) 5997c3eed5cSTejun Heo { 60054d5b7d0SLai Jiangshan unsigned long data = atomic_long_read(&work->data); 6017c3eed5cSTejun Heo 602112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 603112202d9STejun Heo return ((struct pool_workqueue *) 60454d5b7d0SLai Jiangshan (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; 60554d5b7d0SLai Jiangshan 60654d5b7d0SLai Jiangshan return data >> WORK_OFFQ_POOL_SHIFT; 6077c3eed5cSTejun Heo } 6087c3eed5cSTejun Heo 609bbb68dfaSTejun Heo static void mark_work_canceling(struct work_struct *work) 610bbb68dfaSTejun Heo { 6117c3eed5cSTejun Heo unsigned long pool_id = get_work_pool_id(work); 612bbb68dfaSTejun Heo 6137c3eed5cSTejun Heo pool_id <<= WORK_OFFQ_POOL_SHIFT; 6147c3eed5cSTejun Heo set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); 615bbb68dfaSTejun Heo } 616bbb68dfaSTejun Heo 617bbb68dfaSTejun Heo static bool work_is_canceling(struct work_struct *work) 618bbb68dfaSTejun Heo { 619bbb68dfaSTejun Heo unsigned long data = atomic_long_read(&work->data); 620bbb68dfaSTejun Heo 621112202d9STejun Heo return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); 622bbb68dfaSTejun Heo } 623bbb68dfaSTejun Heo 624e22bee78STejun Heo /* 6253270476aSTejun Heo * Policy functions. These define the policies on how the global worker 6263270476aSTejun Heo * pools are managed. Unless noted otherwise, these functions assume that 627d565ed63STejun Heo * they're being called with pool->lock held. 628e22bee78STejun Heo */ 629e22bee78STejun Heo 63063d95a91STejun Heo static bool __need_more_worker(struct worker_pool *pool) 631649027d7STejun Heo { 632e19e397aSTejun Heo return !atomic_read(&pool->nr_running); 633649027d7STejun Heo } 634649027d7STejun Heo 635e22bee78STejun Heo /* 636e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 637e22bee78STejun Heo * running workers. 638974271c4STejun Heo * 639974271c4STejun Heo * Note that, because unbound workers never contribute to nr_running, this 640706026c2STejun Heo * function will always return %true for unbound pools as long as the 641974271c4STejun Heo * worklist isn't empty. 642e22bee78STejun Heo */ 64363d95a91STejun Heo static bool need_more_worker(struct worker_pool *pool) 644e22bee78STejun Heo { 64563d95a91STejun Heo return !list_empty(&pool->worklist) && __need_more_worker(pool); 646e22bee78STejun Heo } 647e22bee78STejun Heo 648e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 64963d95a91STejun Heo static bool may_start_working(struct worker_pool *pool) 650e22bee78STejun Heo { 65163d95a91STejun Heo return pool->nr_idle; 652e22bee78STejun Heo } 653e22bee78STejun Heo 654e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 65563d95a91STejun Heo static bool keep_working(struct worker_pool *pool) 656e22bee78STejun Heo { 657e19e397aSTejun Heo return !list_empty(&pool->worklist) && 658e19e397aSTejun Heo atomic_read(&pool->nr_running) <= 1; 659e22bee78STejun Heo } 660e22bee78STejun Heo 661e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 66263d95a91STejun Heo static bool need_to_create_worker(struct worker_pool *pool) 663e22bee78STejun Heo { 66463d95a91STejun Heo return need_more_worker(pool) && !may_start_working(pool); 665e22bee78STejun Heo } 666e22bee78STejun Heo 667e22bee78STejun Heo /* Do I need to be the manager? */ 66863d95a91STejun Heo static bool need_to_manage_workers(struct worker_pool *pool) 669e22bee78STejun Heo { 67063d95a91STejun Heo return need_to_create_worker(pool) || 67111ebea50STejun Heo (pool->flags & POOL_MANAGE_WORKERS); 672e22bee78STejun Heo } 673e22bee78STejun Heo 674e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 67563d95a91STejun Heo static bool too_many_workers(struct worker_pool *pool) 676e22bee78STejun Heo { 677552a37e9SLai Jiangshan bool managing = pool->flags & POOL_MANAGING_WORKERS; 67863d95a91STejun Heo int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 67963d95a91STejun Heo int nr_busy = pool->nr_workers - nr_idle; 680e22bee78STejun Heo 681ea1abd61SLai Jiangshan /* 682ea1abd61SLai Jiangshan * nr_idle and idle_list may disagree if idle rebinding is in 683ea1abd61SLai Jiangshan * progress. Never return %true if idle_list is empty. 684ea1abd61SLai Jiangshan */ 685ea1abd61SLai Jiangshan if (list_empty(&pool->idle_list)) 686ea1abd61SLai Jiangshan return false; 687ea1abd61SLai Jiangshan 688e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 689e22bee78STejun Heo } 690e22bee78STejun Heo 691e22bee78STejun Heo /* 692e22bee78STejun Heo * Wake up functions. 693e22bee78STejun Heo */ 694e22bee78STejun Heo 6957e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 69663d95a91STejun Heo static struct worker *first_worker(struct worker_pool *pool) 6977e11629dSTejun Heo { 69863d95a91STejun Heo if (unlikely(list_empty(&pool->idle_list))) 6997e11629dSTejun Heo return NULL; 7007e11629dSTejun Heo 70163d95a91STejun Heo return list_first_entry(&pool->idle_list, struct worker, entry); 7027e11629dSTejun Heo } 7037e11629dSTejun Heo 7047e11629dSTejun Heo /** 7057e11629dSTejun Heo * wake_up_worker - wake up an idle worker 70663d95a91STejun Heo * @pool: worker pool to wake worker from 7077e11629dSTejun Heo * 70863d95a91STejun Heo * Wake up the first idle worker of @pool. 7097e11629dSTejun Heo * 7107e11629dSTejun Heo * CONTEXT: 711d565ed63STejun Heo * spin_lock_irq(pool->lock). 7127e11629dSTejun Heo */ 71363d95a91STejun Heo static void wake_up_worker(struct worker_pool *pool) 7147e11629dSTejun Heo { 71563d95a91STejun Heo struct worker *worker = first_worker(pool); 7167e11629dSTejun Heo 7177e11629dSTejun Heo if (likely(worker)) 7187e11629dSTejun Heo wake_up_process(worker->task); 7197e11629dSTejun Heo } 7207e11629dSTejun Heo 7214690c4abSTejun Heo /** 722e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 723e22bee78STejun Heo * @task: task waking up 724e22bee78STejun Heo * @cpu: CPU @task is waking up to 725e22bee78STejun Heo * 726e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 727e22bee78STejun Heo * being awoken. 728e22bee78STejun Heo * 729e22bee78STejun Heo * CONTEXT: 730e22bee78STejun Heo * spin_lock_irq(rq->lock) 731e22bee78STejun Heo */ 732d84ff051STejun Heo void wq_worker_waking_up(struct task_struct *task, int cpu) 733e22bee78STejun Heo { 734e22bee78STejun Heo struct worker *worker = kthread_data(task); 735e22bee78STejun Heo 73636576000SJoonsoo Kim if (!(worker->flags & WORKER_NOT_RUNNING)) { 737ec22ca5eSTejun Heo WARN_ON_ONCE(worker->pool->cpu != cpu); 738e19e397aSTejun Heo atomic_inc(&worker->pool->nr_running); 739e22bee78STejun Heo } 74036576000SJoonsoo Kim } 741e22bee78STejun Heo 742e22bee78STejun Heo /** 743e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 744e22bee78STejun Heo * @task: task going to sleep 745e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 746e22bee78STejun Heo * 747e22bee78STejun Heo * This function is called during schedule() when a busy worker is 748e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 749e22bee78STejun Heo * returning pointer to its task. 750e22bee78STejun Heo * 751e22bee78STejun Heo * CONTEXT: 752e22bee78STejun Heo * spin_lock_irq(rq->lock) 753e22bee78STejun Heo * 754e22bee78STejun Heo * RETURNS: 755e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 756e22bee78STejun Heo */ 757d84ff051STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu) 758e22bee78STejun Heo { 759e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 760111c225aSTejun Heo struct worker_pool *pool; 761e22bee78STejun Heo 762111c225aSTejun Heo /* 763111c225aSTejun Heo * Rescuers, which may not have all the fields set up like normal 764111c225aSTejun Heo * workers, also reach here, let's not access anything before 765111c225aSTejun Heo * checking NOT_RUNNING. 766111c225aSTejun Heo */ 7672d64672eSSteven Rostedt if (worker->flags & WORKER_NOT_RUNNING) 768e22bee78STejun Heo return NULL; 769e22bee78STejun Heo 770111c225aSTejun Heo pool = worker->pool; 771111c225aSTejun Heo 772e22bee78STejun Heo /* this can only happen on the local cpu */ 7736183c009STejun Heo if (WARN_ON_ONCE(cpu != raw_smp_processor_id())) 7746183c009STejun Heo return NULL; 775e22bee78STejun Heo 776e22bee78STejun Heo /* 777e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 778e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 779e22bee78STejun Heo * Please read comment there. 780e22bee78STejun Heo * 781628c78e7STejun Heo * NOT_RUNNING is clear. This means that we're bound to and 782628c78e7STejun Heo * running on the local cpu w/ rq lock held and preemption 783628c78e7STejun Heo * disabled, which in turn means that none else could be 784d565ed63STejun Heo * manipulating idle_list, so dereferencing idle_list without pool 785628c78e7STejun Heo * lock is safe. 786e22bee78STejun Heo */ 787e19e397aSTejun Heo if (atomic_dec_and_test(&pool->nr_running) && 788e19e397aSTejun Heo !list_empty(&pool->worklist)) 78963d95a91STejun Heo to_wakeup = first_worker(pool); 790e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 791e22bee78STejun Heo } 792e22bee78STejun Heo 793e22bee78STejun Heo /** 794e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 795cb444766STejun Heo * @worker: self 796d302f017STejun Heo * @flags: flags to set 797d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 798d302f017STejun Heo * 799e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 800e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 801e22bee78STejun Heo * woken up. 802d302f017STejun Heo * 803cb444766STejun Heo * CONTEXT: 804d565ed63STejun Heo * spin_lock_irq(pool->lock) 805d302f017STejun Heo */ 806d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 807d302f017STejun Heo bool wakeup) 808d302f017STejun Heo { 809bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 810e22bee78STejun Heo 811cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 812cb444766STejun Heo 813e22bee78STejun Heo /* 814e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 815e22bee78STejun Heo * wake up an idle worker as necessary if requested by 816e22bee78STejun Heo * @wakeup. 817e22bee78STejun Heo */ 818e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 819e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 820e22bee78STejun Heo if (wakeup) { 821e19e397aSTejun Heo if (atomic_dec_and_test(&pool->nr_running) && 822bd7bdd43STejun Heo !list_empty(&pool->worklist)) 82363d95a91STejun Heo wake_up_worker(pool); 824e22bee78STejun Heo } else 825e19e397aSTejun Heo atomic_dec(&pool->nr_running); 826e22bee78STejun Heo } 827e22bee78STejun Heo 828d302f017STejun Heo worker->flags |= flags; 829d302f017STejun Heo } 830d302f017STejun Heo 831d302f017STejun Heo /** 832e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 833cb444766STejun Heo * @worker: self 834d302f017STejun Heo * @flags: flags to clear 835d302f017STejun Heo * 836e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 837d302f017STejun Heo * 838cb444766STejun Heo * CONTEXT: 839d565ed63STejun Heo * spin_lock_irq(pool->lock) 840d302f017STejun Heo */ 841d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 842d302f017STejun Heo { 84363d95a91STejun Heo struct worker_pool *pool = worker->pool; 844e22bee78STejun Heo unsigned int oflags = worker->flags; 845e22bee78STejun Heo 846cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 847cb444766STejun Heo 848d302f017STejun Heo worker->flags &= ~flags; 849e22bee78STejun Heo 85042c025f3STejun Heo /* 85142c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 85242c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 85342c025f3STejun Heo * of multiple flags, not a single flag. 85442c025f3STejun Heo */ 855e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 856e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 857e19e397aSTejun Heo atomic_inc(&pool->nr_running); 858d302f017STejun Heo } 859d302f017STejun Heo 860d302f017STejun Heo /** 8618cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 862c9e7cf27STejun Heo * @pool: pool of interest 8638cca0eeaSTejun Heo * @work: work to find worker for 8648cca0eeaSTejun Heo * 865c9e7cf27STejun Heo * Find a worker which is executing @work on @pool by searching 866c9e7cf27STejun Heo * @pool->busy_hash which is keyed by the address of @work. For a worker 867a2c1c57bSTejun Heo * to match, its current execution should match the address of @work and 868a2c1c57bSTejun Heo * its work function. This is to avoid unwanted dependency between 869a2c1c57bSTejun Heo * unrelated work executions through a work item being recycled while still 870a2c1c57bSTejun Heo * being executed. 871a2c1c57bSTejun Heo * 872a2c1c57bSTejun Heo * This is a bit tricky. A work item may be freed once its execution 873a2c1c57bSTejun Heo * starts and nothing prevents the freed area from being recycled for 874a2c1c57bSTejun Heo * another work item. If the same work item address ends up being reused 875a2c1c57bSTejun Heo * before the original execution finishes, workqueue will identify the 876a2c1c57bSTejun Heo * recycled work item as currently executing and make it wait until the 877a2c1c57bSTejun Heo * current execution finishes, introducing an unwanted dependency. 878a2c1c57bSTejun Heo * 879a2c1c57bSTejun Heo * This function checks the work item address, work function and workqueue 880a2c1c57bSTejun Heo * to avoid false positives. Note that this isn't complete as one may 881a2c1c57bSTejun Heo * construct a work function which can introduce dependency onto itself 882a2c1c57bSTejun Heo * through a recycled work item. Well, if somebody wants to shoot oneself 883a2c1c57bSTejun Heo * in the foot that badly, there's only so much we can do, and if such 884a2c1c57bSTejun Heo * deadlock actually occurs, it should be easy to locate the culprit work 885a2c1c57bSTejun Heo * function. 8868cca0eeaSTejun Heo * 8878cca0eeaSTejun Heo * CONTEXT: 888d565ed63STejun Heo * spin_lock_irq(pool->lock). 8898cca0eeaSTejun Heo * 8908cca0eeaSTejun Heo * RETURNS: 8918cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8928cca0eeaSTejun Heo * otherwise. 8938cca0eeaSTejun Heo */ 894c9e7cf27STejun Heo static struct worker *find_worker_executing_work(struct worker_pool *pool, 8958cca0eeaSTejun Heo struct work_struct *work) 8968cca0eeaSTejun Heo { 89742f8570fSSasha Levin struct worker *worker; 89842f8570fSSasha Levin 899b67bfe0dSSasha Levin hash_for_each_possible(pool->busy_hash, worker, hentry, 900a2c1c57bSTejun Heo (unsigned long)work) 901a2c1c57bSTejun Heo if (worker->current_work == work && 902a2c1c57bSTejun Heo worker->current_func == work->func) 90342f8570fSSasha Levin return worker; 90442f8570fSSasha Levin 90542f8570fSSasha Levin return NULL; 9068cca0eeaSTejun Heo } 9078cca0eeaSTejun Heo 9088cca0eeaSTejun Heo /** 909bf4ede01STejun Heo * move_linked_works - move linked works to a list 910bf4ede01STejun Heo * @work: start of series of works to be scheduled 911bf4ede01STejun Heo * @head: target list to append @work to 912bf4ede01STejun Heo * @nextp: out paramter for nested worklist walking 913bf4ede01STejun Heo * 914bf4ede01STejun Heo * Schedule linked works starting from @work to @head. Work series to 915bf4ede01STejun Heo * be scheduled starts at @work and includes any consecutive work with 916bf4ede01STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 917bf4ede01STejun Heo * 918bf4ede01STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 919bf4ede01STejun Heo * the last scheduled work. This allows move_linked_works() to be 920bf4ede01STejun Heo * nested inside outer list_for_each_entry_safe(). 921bf4ede01STejun Heo * 922bf4ede01STejun Heo * CONTEXT: 923d565ed63STejun Heo * spin_lock_irq(pool->lock). 924bf4ede01STejun Heo */ 925bf4ede01STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 926bf4ede01STejun Heo struct work_struct **nextp) 927bf4ede01STejun Heo { 928bf4ede01STejun Heo struct work_struct *n; 929bf4ede01STejun Heo 930bf4ede01STejun Heo /* 931bf4ede01STejun Heo * Linked worklist will always end before the end of the list, 932bf4ede01STejun Heo * use NULL for list head. 933bf4ede01STejun Heo */ 934bf4ede01STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 935bf4ede01STejun Heo list_move_tail(&work->entry, head); 936bf4ede01STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 937bf4ede01STejun Heo break; 938bf4ede01STejun Heo } 939bf4ede01STejun Heo 940bf4ede01STejun Heo /* 941bf4ede01STejun Heo * If we're already inside safe list traversal and have moved 942bf4ede01STejun Heo * multiple works to the scheduled queue, the next position 943bf4ede01STejun Heo * needs to be updated. 944bf4ede01STejun Heo */ 945bf4ede01STejun Heo if (nextp) 946bf4ede01STejun Heo *nextp = n; 947bf4ede01STejun Heo } 948bf4ede01STejun Heo 949112202d9STejun Heo static void pwq_activate_delayed_work(struct work_struct *work) 950bf4ede01STejun Heo { 951112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 952bf4ede01STejun Heo 953bf4ede01STejun Heo trace_workqueue_activate_work(work); 954112202d9STejun Heo move_linked_works(work, &pwq->pool->worklist, NULL); 955bf4ede01STejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 956112202d9STejun Heo pwq->nr_active++; 957bf4ede01STejun Heo } 958bf4ede01STejun Heo 959112202d9STejun Heo static void pwq_activate_first_delayed(struct pool_workqueue *pwq) 9603aa62497SLai Jiangshan { 961112202d9STejun Heo struct work_struct *work = list_first_entry(&pwq->delayed_works, 9623aa62497SLai Jiangshan struct work_struct, entry); 9633aa62497SLai Jiangshan 964112202d9STejun Heo pwq_activate_delayed_work(work); 9653aa62497SLai Jiangshan } 9663aa62497SLai Jiangshan 967bf4ede01STejun Heo /** 968112202d9STejun Heo * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight 969112202d9STejun Heo * @pwq: pwq of interest 970bf4ede01STejun Heo * @color: color of work which left the queue 971bf4ede01STejun Heo * 972bf4ede01STejun Heo * A work either has completed or is removed from pending queue, 973112202d9STejun Heo * decrement nr_in_flight of its pwq and handle workqueue flushing. 974bf4ede01STejun Heo * 975bf4ede01STejun Heo * CONTEXT: 976d565ed63STejun Heo * spin_lock_irq(pool->lock). 977bf4ede01STejun Heo */ 978112202d9STejun Heo static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) 979bf4ede01STejun Heo { 980bf4ede01STejun Heo /* ignore uncolored works */ 981bf4ede01STejun Heo if (color == WORK_NO_COLOR) 982bf4ede01STejun Heo return; 983bf4ede01STejun Heo 984112202d9STejun Heo pwq->nr_in_flight[color]--; 985bf4ede01STejun Heo 986112202d9STejun Heo pwq->nr_active--; 987112202d9STejun Heo if (!list_empty(&pwq->delayed_works)) { 988bf4ede01STejun Heo /* one down, submit a delayed one */ 989112202d9STejun Heo if (pwq->nr_active < pwq->max_active) 990112202d9STejun Heo pwq_activate_first_delayed(pwq); 991bf4ede01STejun Heo } 992bf4ede01STejun Heo 993bf4ede01STejun Heo /* is flush in progress and are we at the flushing tip? */ 994112202d9STejun Heo if (likely(pwq->flush_color != color)) 995bf4ede01STejun Heo return; 996bf4ede01STejun Heo 997bf4ede01STejun Heo /* are there still in-flight works? */ 998112202d9STejun Heo if (pwq->nr_in_flight[color]) 999bf4ede01STejun Heo return; 1000bf4ede01STejun Heo 1001112202d9STejun Heo /* this pwq is done, clear flush_color */ 1002112202d9STejun Heo pwq->flush_color = -1; 1003bf4ede01STejun Heo 1004bf4ede01STejun Heo /* 1005112202d9STejun Heo * If this was the last pwq, wake up the first flusher. It 1006bf4ede01STejun Heo * will handle the rest. 1007bf4ede01STejun Heo */ 1008112202d9STejun Heo if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) 1009112202d9STejun Heo complete(&pwq->wq->first_flusher->done); 1010bf4ede01STejun Heo } 1011bf4ede01STejun Heo 101236e227d2STejun Heo /** 1013bbb68dfaSTejun Heo * try_to_grab_pending - steal work item from worklist and disable irq 101436e227d2STejun Heo * @work: work item to steal 101536e227d2STejun Heo * @is_dwork: @work is a delayed_work 1016bbb68dfaSTejun Heo * @flags: place to store irq state 101736e227d2STejun Heo * 101836e227d2STejun Heo * Try to grab PENDING bit of @work. This function can handle @work in any 101936e227d2STejun Heo * stable state - idle, on timer or on worklist. Return values are 102036e227d2STejun Heo * 102136e227d2STejun Heo * 1 if @work was pending and we successfully stole PENDING 102236e227d2STejun Heo * 0 if @work was idle and we claimed PENDING 102336e227d2STejun Heo * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 1024bbb68dfaSTejun Heo * -ENOENT if someone else is canceling @work, this state may persist 1025bbb68dfaSTejun Heo * for arbitrarily long 102636e227d2STejun Heo * 1027bbb68dfaSTejun Heo * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 1028e0aecdd8STejun Heo * interrupted while holding PENDING and @work off queue, irq must be 1029e0aecdd8STejun Heo * disabled on entry. This, combined with delayed_work->timer being 1030e0aecdd8STejun Heo * irqsafe, ensures that we return -EAGAIN for finite short period of time. 1031bbb68dfaSTejun Heo * 1032bbb68dfaSTejun Heo * On successful return, >= 0, irq is disabled and the caller is 1033bbb68dfaSTejun Heo * responsible for releasing it using local_irq_restore(*@flags). 1034bbb68dfaSTejun Heo * 1035e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 1036bf4ede01STejun Heo */ 1037bbb68dfaSTejun Heo static int try_to_grab_pending(struct work_struct *work, bool is_dwork, 1038bbb68dfaSTejun Heo unsigned long *flags) 1039bf4ede01STejun Heo { 1040d565ed63STejun Heo struct worker_pool *pool; 1041112202d9STejun Heo struct pool_workqueue *pwq; 1042bf4ede01STejun Heo 1043bbb68dfaSTejun Heo local_irq_save(*flags); 1044bbb68dfaSTejun Heo 104536e227d2STejun Heo /* try to steal the timer if it exists */ 104636e227d2STejun Heo if (is_dwork) { 104736e227d2STejun Heo struct delayed_work *dwork = to_delayed_work(work); 104836e227d2STejun Heo 1049e0aecdd8STejun Heo /* 1050e0aecdd8STejun Heo * dwork->timer is irqsafe. If del_timer() fails, it's 1051e0aecdd8STejun Heo * guaranteed that the timer is not queued anywhere and not 1052e0aecdd8STejun Heo * running on the local CPU. 1053e0aecdd8STejun Heo */ 105436e227d2STejun Heo if (likely(del_timer(&dwork->timer))) 105536e227d2STejun Heo return 1; 105636e227d2STejun Heo } 105736e227d2STejun Heo 105836e227d2STejun Heo /* try to claim PENDING the normal way */ 1059bf4ede01STejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 1060bf4ede01STejun Heo return 0; 1061bf4ede01STejun Heo 1062bf4ede01STejun Heo /* 1063bf4ede01STejun Heo * The queueing is in progress, or it is already queued. Try to 1064bf4ede01STejun Heo * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 1065bf4ede01STejun Heo */ 1066d565ed63STejun Heo pool = get_work_pool(work); 1067d565ed63STejun Heo if (!pool) 1068bbb68dfaSTejun Heo goto fail; 1069bf4ede01STejun Heo 1070d565ed63STejun Heo spin_lock(&pool->lock); 1071bf4ede01STejun Heo /* 1072112202d9STejun Heo * work->data is guaranteed to point to pwq only while the work 1073112202d9STejun Heo * item is queued on pwq->wq, and both updating work->data to point 1074112202d9STejun Heo * to pwq on queueing and to pool on dequeueing are done under 1075112202d9STejun Heo * pwq->pool->lock. This in turn guarantees that, if work->data 1076112202d9STejun Heo * points to pwq which is associated with a locked pool, the work 10770b3dae68SLai Jiangshan * item is currently queued on that pool. 1078bf4ede01STejun Heo */ 1079112202d9STejun Heo pwq = get_work_pwq(work); 1080112202d9STejun Heo if (pwq && pwq->pool == pool) { 1081bf4ede01STejun Heo debug_work_deactivate(work); 10823aa62497SLai Jiangshan 10833aa62497SLai Jiangshan /* 108416062836STejun Heo * A delayed work item cannot be grabbed directly because 108516062836STejun Heo * it might have linked NO_COLOR work items which, if left 1086112202d9STejun Heo * on the delayed_list, will confuse pwq->nr_active 108716062836STejun Heo * management later on and cause stall. Make sure the work 108816062836STejun Heo * item is activated before grabbing. 10893aa62497SLai Jiangshan */ 10903aa62497SLai Jiangshan if (*work_data_bits(work) & WORK_STRUCT_DELAYED) 1091112202d9STejun Heo pwq_activate_delayed_work(work); 10923aa62497SLai Jiangshan 1093bf4ede01STejun Heo list_del_init(&work->entry); 1094112202d9STejun Heo pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work)); 109536e227d2STejun Heo 1096112202d9STejun Heo /* work->data points to pwq iff queued, point to pool */ 10974468a00fSLai Jiangshan set_work_pool_and_keep_pending(work, pool->id); 10984468a00fSLai Jiangshan 1099d565ed63STejun Heo spin_unlock(&pool->lock); 110036e227d2STejun Heo return 1; 1101bf4ede01STejun Heo } 1102d565ed63STejun Heo spin_unlock(&pool->lock); 1103bbb68dfaSTejun Heo fail: 1104bbb68dfaSTejun Heo local_irq_restore(*flags); 1105bbb68dfaSTejun Heo if (work_is_canceling(work)) 1106bbb68dfaSTejun Heo return -ENOENT; 1107bbb68dfaSTejun Heo cpu_relax(); 110836e227d2STejun Heo return -EAGAIN; 1109bf4ede01STejun Heo } 1110bf4ede01STejun Heo 1111bf4ede01STejun Heo /** 1112706026c2STejun Heo * insert_work - insert a work into a pool 1113112202d9STejun Heo * @pwq: pwq @work belongs to 11144690c4abSTejun Heo * @work: work to insert 11154690c4abSTejun Heo * @head: insertion point 11164690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 11174690c4abSTejun Heo * 1118112202d9STejun Heo * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to 1119706026c2STejun Heo * work_struct flags. 11204690c4abSTejun Heo * 11214690c4abSTejun Heo * CONTEXT: 1122d565ed63STejun Heo * spin_lock_irq(pool->lock). 1123365970a1SDavid Howells */ 1124112202d9STejun Heo static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, 1125112202d9STejun Heo struct list_head *head, unsigned int extra_flags) 1126b89deed3SOleg Nesterov { 1127112202d9STejun Heo struct worker_pool *pool = pwq->pool; 1128e1d8aa9fSFrederic Weisbecker 11294690c4abSTejun Heo /* we own @work, set data and link */ 1130112202d9STejun Heo set_work_pwq(work, pwq, extra_flags); 11311a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 1132e22bee78STejun Heo 1133e22bee78STejun Heo /* 1134e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 1135e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 1136e22bee78STejun Heo * lying around lazily while there are works to be processed. 1137e22bee78STejun Heo */ 1138e22bee78STejun Heo smp_mb(); 1139e22bee78STejun Heo 114063d95a91STejun Heo if (__need_more_worker(pool)) 114163d95a91STejun Heo wake_up_worker(pool); 1142b89deed3SOleg Nesterov } 1143b89deed3SOleg Nesterov 1144c8efcc25STejun Heo /* 1145c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 11468d03ecfeSTejun Heo * same workqueue. 1147c8efcc25STejun Heo */ 1148c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 1149c8efcc25STejun Heo { 1150c8efcc25STejun Heo struct worker *worker; 1151c8efcc25STejun Heo 11528d03ecfeSTejun Heo worker = current_wq_worker(); 1153c8efcc25STejun Heo /* 11548d03ecfeSTejun Heo * Return %true iff I'm a worker execuing a work item on @wq. If 11558d03ecfeSTejun Heo * I'm @worker, it's safe to dereference it without locking. 1156c8efcc25STejun Heo */ 1157112202d9STejun Heo return worker && worker->current_pwq->wq == wq; 1158c8efcc25STejun Heo } 1159c8efcc25STejun Heo 1160d84ff051STejun Heo static void __queue_work(int cpu, struct workqueue_struct *wq, 11611da177e4SLinus Torvalds struct work_struct *work) 11621da177e4SLinus Torvalds { 1163112202d9STejun Heo struct pool_workqueue *pwq; 11641e19ffc6STejun Heo struct list_head *worklist; 11658a2e8e5dSTejun Heo unsigned int work_flags; 1166b75cac93SJoonsoo Kim unsigned int req_cpu = cpu; 11678930cabaSTejun Heo 11688930cabaSTejun Heo /* 11698930cabaSTejun Heo * While a work item is PENDING && off queue, a task trying to 11708930cabaSTejun Heo * steal the PENDING will busy-loop waiting for it to either get 11718930cabaSTejun Heo * queued or lose PENDING. Grabbing PENDING and queueing should 11728930cabaSTejun Heo * happen with IRQ disabled. 11738930cabaSTejun Heo */ 11748930cabaSTejun Heo WARN_ON_ONCE(!irqs_disabled()); 11751da177e4SLinus Torvalds 1176dc186ad7SThomas Gleixner debug_work_activate(work); 11771e19ffc6STejun Heo 1178c8efcc25STejun Heo /* if dying, only works from the same workqueue are allowed */ 11799c5a2ba7STejun Heo if (unlikely(wq->flags & WQ_DRAINING) && 1180c8efcc25STejun Heo WARN_ON_ONCE(!is_chained_work(wq))) 1181e41e704bSTejun Heo return; 1182e41e704bSTejun Heo 1183112202d9STejun Heo /* determine the pwq to use */ 1184c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1185c9e7cf27STejun Heo struct worker_pool *last_pool; 1186c7fc77f7STejun Heo 118757469821STejun Heo if (cpu == WORK_CPU_UNBOUND) 1188f3421797STejun Heo cpu = raw_smp_processor_id(); 1189f3421797STejun Heo 119018aa9effSTejun Heo /* 1191dbf2576eSTejun Heo * It's multi cpu. If @work was previously on a different 1192dbf2576eSTejun Heo * cpu, it might still be running there, in which case the 1193dbf2576eSTejun Heo * work needs to be queued on that cpu to guarantee 1194dbf2576eSTejun Heo * non-reentrancy. 119518aa9effSTejun Heo */ 1196112202d9STejun Heo pwq = get_pwq(cpu, wq); 1197c9e7cf27STejun Heo last_pool = get_work_pool(work); 1198dbf2576eSTejun Heo 1199112202d9STejun Heo if (last_pool && last_pool != pwq->pool) { 120018aa9effSTejun Heo struct worker *worker; 120118aa9effSTejun Heo 1202d565ed63STejun Heo spin_lock(&last_pool->lock); 120318aa9effSTejun Heo 1204c9e7cf27STejun Heo worker = find_worker_executing_work(last_pool, work); 120518aa9effSTejun Heo 1206112202d9STejun Heo if (worker && worker->current_pwq->wq == wq) { 1207112202d9STejun Heo pwq = get_pwq(last_pool->cpu, wq); 12088594fadeSLai Jiangshan } else { 120918aa9effSTejun Heo /* meh... not running there, queue here */ 1210d565ed63STejun Heo spin_unlock(&last_pool->lock); 1211112202d9STejun Heo spin_lock(&pwq->pool->lock); 121218aa9effSTejun Heo } 12138930cabaSTejun Heo } else { 1214112202d9STejun Heo spin_lock(&pwq->pool->lock); 12158930cabaSTejun Heo } 1216f3421797STejun Heo } else { 1217112202d9STejun Heo pwq = get_pwq(WORK_CPU_UNBOUND, wq); 1218112202d9STejun Heo spin_lock(&pwq->pool->lock); 1219502ca9d8STejun Heo } 1220502ca9d8STejun Heo 1221112202d9STejun Heo /* pwq determined, queue */ 1222112202d9STejun Heo trace_workqueue_queue_work(req_cpu, pwq, work); 1223502ca9d8STejun Heo 1224f5b2552bSDan Carpenter if (WARN_ON(!list_empty(&work->entry))) { 1225112202d9STejun Heo spin_unlock(&pwq->pool->lock); 1226f5b2552bSDan Carpenter return; 1227f5b2552bSDan Carpenter } 12281e19ffc6STejun Heo 1229112202d9STejun Heo pwq->nr_in_flight[pwq->work_color]++; 1230112202d9STejun Heo work_flags = work_color_to_flags(pwq->work_color); 12311e19ffc6STejun Heo 1232112202d9STejun Heo if (likely(pwq->nr_active < pwq->max_active)) { 1233cdadf009STejun Heo trace_workqueue_activate_work(work); 1234112202d9STejun Heo pwq->nr_active++; 1235112202d9STejun Heo worklist = &pwq->pool->worklist; 12368a2e8e5dSTejun Heo } else { 12378a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 1238112202d9STejun Heo worklist = &pwq->delayed_works; 12398a2e8e5dSTejun Heo } 12401e19ffc6STejun Heo 1241112202d9STejun Heo insert_work(pwq, work, worklist, work_flags); 12421e19ffc6STejun Heo 1243112202d9STejun Heo spin_unlock(&pwq->pool->lock); 12441da177e4SLinus Torvalds } 12451da177e4SLinus Torvalds 12460fcb78c2SRolf Eike Beer /** 1247c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1248c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1249c1a220e7SZhang Rui * @wq: workqueue to use 1250c1a220e7SZhang Rui * @work: work to queue 1251c1a220e7SZhang Rui * 1252d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 1253c1a220e7SZhang Rui * 1254c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1255c1a220e7SZhang Rui * can't go away. 1256c1a220e7SZhang Rui */ 1257d4283e93STejun Heo bool queue_work_on(int cpu, struct workqueue_struct *wq, 1258d4283e93STejun Heo struct work_struct *work) 1259c1a220e7SZhang Rui { 1260d4283e93STejun Heo bool ret = false; 12618930cabaSTejun Heo unsigned long flags; 12628930cabaSTejun Heo 12638930cabaSTejun Heo local_irq_save(flags); 1264c1a220e7SZhang Rui 126522df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 12664690c4abSTejun Heo __queue_work(cpu, wq, work); 1267d4283e93STejun Heo ret = true; 1268c1a220e7SZhang Rui } 12698930cabaSTejun Heo 12708930cabaSTejun Heo local_irq_restore(flags); 1271c1a220e7SZhang Rui return ret; 1272c1a220e7SZhang Rui } 1273c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1274c1a220e7SZhang Rui 12750a13c00eSTejun Heo /** 12760a13c00eSTejun Heo * queue_work - queue work on a workqueue 12770a13c00eSTejun Heo * @wq: workqueue to use 12780a13c00eSTejun Heo * @work: work to queue 12790a13c00eSTejun Heo * 1280d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 12810a13c00eSTejun Heo * 12820a13c00eSTejun Heo * We queue the work to the CPU on which it was submitted, but if the CPU dies 12830a13c00eSTejun Heo * it can be processed by another CPU. 12840a13c00eSTejun Heo */ 1285d4283e93STejun Heo bool queue_work(struct workqueue_struct *wq, struct work_struct *work) 12860a13c00eSTejun Heo { 128757469821STejun Heo return queue_work_on(WORK_CPU_UNBOUND, wq, work); 12880a13c00eSTejun Heo } 12890a13c00eSTejun Heo EXPORT_SYMBOL_GPL(queue_work); 12900a13c00eSTejun Heo 1291d8e794dfSTejun Heo void delayed_work_timer_fn(unsigned long __data) 12921da177e4SLinus Torvalds { 129352bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 12941da177e4SLinus Torvalds 1295e0aecdd8STejun Heo /* should have been called from irqsafe timer with irq already off */ 129660c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 12971da177e4SLinus Torvalds } 12981438ade5SKonstantin Khlebnikov EXPORT_SYMBOL(delayed_work_timer_fn); 12991da177e4SLinus Torvalds 13007beb2edfSTejun Heo static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 130152bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 13021da177e4SLinus Torvalds { 13037beb2edfSTejun Heo struct timer_list *timer = &dwork->timer; 13047beb2edfSTejun Heo struct work_struct *work = &dwork->work; 13051da177e4SLinus Torvalds 13067beb2edfSTejun Heo WARN_ON_ONCE(timer->function != delayed_work_timer_fn || 13077beb2edfSTejun Heo timer->data != (unsigned long)dwork); 1308fc4b514fSTejun Heo WARN_ON_ONCE(timer_pending(timer)); 1309fc4b514fSTejun Heo WARN_ON_ONCE(!list_empty(&work->entry)); 13107beb2edfSTejun Heo 13118852aac2STejun Heo /* 13128852aac2STejun Heo * If @delay is 0, queue @dwork->work immediately. This is for 13138852aac2STejun Heo * both optimization and correctness. The earliest @timer can 13148852aac2STejun Heo * expire is on the closest next tick and delayed_work users depend 13158852aac2STejun Heo * on that there's no such delay when @delay is 0. 13168852aac2STejun Heo */ 13178852aac2STejun Heo if (!delay) { 13188852aac2STejun Heo __queue_work(cpu, wq, &dwork->work); 13198852aac2STejun Heo return; 13208852aac2STejun Heo } 13218852aac2STejun Heo 13227beb2edfSTejun Heo timer_stats_timer_set_start_info(&dwork->timer); 13237beb2edfSTejun Heo 132460c057bcSLai Jiangshan dwork->wq = wq; 13251265057fSTejun Heo dwork->cpu = cpu; 13267beb2edfSTejun Heo timer->expires = jiffies + delay; 13277beb2edfSTejun Heo 13287beb2edfSTejun Heo if (unlikely(cpu != WORK_CPU_UNBOUND)) 13297beb2edfSTejun Heo add_timer_on(timer, cpu); 13307beb2edfSTejun Heo else 13317beb2edfSTejun Heo add_timer(timer); 13327beb2edfSTejun Heo } 13331da177e4SLinus Torvalds 13340fcb78c2SRolf Eike Beer /** 13350fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 13360fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 13370fcb78c2SRolf Eike Beer * @wq: workqueue to use 1338af9997e4SRandy Dunlap * @dwork: work to queue 13390fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 13400fcb78c2SRolf Eike Beer * 1341715f1300STejun Heo * Returns %false if @work was already on a queue, %true otherwise. If 1342715f1300STejun Heo * @delay is zero and @dwork is idle, it will be scheduled for immediate 1343715f1300STejun Heo * execution. 13440fcb78c2SRolf Eike Beer */ 1345d4283e93STejun Heo bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 134652bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 13477a6bc1cdSVenkatesh Pallipadi { 134852bad64dSDavid Howells struct work_struct *work = &dwork->work; 1349d4283e93STejun Heo bool ret = false; 13508930cabaSTejun Heo unsigned long flags; 13518930cabaSTejun Heo 13528930cabaSTejun Heo /* read the comment in __queue_work() */ 13538930cabaSTejun Heo local_irq_save(flags); 13547a6bc1cdSVenkatesh Pallipadi 135522df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 13567beb2edfSTejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 1357d4283e93STejun Heo ret = true; 13587a6bc1cdSVenkatesh Pallipadi } 13598930cabaSTejun Heo 13608930cabaSTejun Heo local_irq_restore(flags); 13617a6bc1cdSVenkatesh Pallipadi return ret; 13627a6bc1cdSVenkatesh Pallipadi } 1363ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 13641da177e4SLinus Torvalds 1365c8e55f36STejun Heo /** 13660a13c00eSTejun Heo * queue_delayed_work - queue work on a workqueue after delay 13670a13c00eSTejun Heo * @wq: workqueue to use 13680a13c00eSTejun Heo * @dwork: delayable work to queue 13690a13c00eSTejun Heo * @delay: number of jiffies to wait before queueing 13700a13c00eSTejun Heo * 1371715f1300STejun Heo * Equivalent to queue_delayed_work_on() but tries to use the local CPU. 13720a13c00eSTejun Heo */ 1373d4283e93STejun Heo bool queue_delayed_work(struct workqueue_struct *wq, 13740a13c00eSTejun Heo struct delayed_work *dwork, unsigned long delay) 13750a13c00eSTejun Heo { 137657469821STejun Heo return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); 13770a13c00eSTejun Heo } 13780a13c00eSTejun Heo EXPORT_SYMBOL_GPL(queue_delayed_work); 13790a13c00eSTejun Heo 13800a13c00eSTejun Heo /** 13818376fe22STejun Heo * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 13828376fe22STejun Heo * @cpu: CPU number to execute work on 13838376fe22STejun Heo * @wq: workqueue to use 13848376fe22STejun Heo * @dwork: work to queue 13858376fe22STejun Heo * @delay: number of jiffies to wait before queueing 13868376fe22STejun Heo * 13878376fe22STejun Heo * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 13888376fe22STejun Heo * modify @dwork's timer so that it expires after @delay. If @delay is 13898376fe22STejun Heo * zero, @work is guaranteed to be scheduled immediately regardless of its 13908376fe22STejun Heo * current state. 13918376fe22STejun Heo * 13928376fe22STejun Heo * Returns %false if @dwork was idle and queued, %true if @dwork was 13938376fe22STejun Heo * pending and its timer was modified. 13948376fe22STejun Heo * 1395e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 13968376fe22STejun Heo * See try_to_grab_pending() for details. 13978376fe22STejun Heo */ 13988376fe22STejun Heo bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 13998376fe22STejun Heo struct delayed_work *dwork, unsigned long delay) 14008376fe22STejun Heo { 14018376fe22STejun Heo unsigned long flags; 14028376fe22STejun Heo int ret; 14038376fe22STejun Heo 14048376fe22STejun Heo do { 14058376fe22STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 14068376fe22STejun Heo } while (unlikely(ret == -EAGAIN)); 14078376fe22STejun Heo 14088376fe22STejun Heo if (likely(ret >= 0)) { 14098376fe22STejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 14108376fe22STejun Heo local_irq_restore(flags); 14118376fe22STejun Heo } 14128376fe22STejun Heo 14138376fe22STejun Heo /* -ENOENT from try_to_grab_pending() becomes %true */ 14148376fe22STejun Heo return ret; 14158376fe22STejun Heo } 14168376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work_on); 14178376fe22STejun Heo 14188376fe22STejun Heo /** 14198376fe22STejun Heo * mod_delayed_work - modify delay of or queue a delayed work 14208376fe22STejun Heo * @wq: workqueue to use 14218376fe22STejun Heo * @dwork: work to queue 14228376fe22STejun Heo * @delay: number of jiffies to wait before queueing 14238376fe22STejun Heo * 14248376fe22STejun Heo * mod_delayed_work_on() on local CPU. 14258376fe22STejun Heo */ 14268376fe22STejun Heo bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork, 14278376fe22STejun Heo unsigned long delay) 14288376fe22STejun Heo { 14298376fe22STejun Heo return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); 14308376fe22STejun Heo } 14318376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work); 14328376fe22STejun Heo 14338376fe22STejun Heo /** 1434c8e55f36STejun Heo * worker_enter_idle - enter idle state 1435c8e55f36STejun Heo * @worker: worker which is entering idle state 1436c8e55f36STejun Heo * 1437c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1438c8e55f36STejun Heo * necessary. 1439c8e55f36STejun Heo * 1440c8e55f36STejun Heo * LOCKING: 1441d565ed63STejun Heo * spin_lock_irq(pool->lock). 1442c8e55f36STejun Heo */ 1443c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 14441da177e4SLinus Torvalds { 1445bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1446c8e55f36STejun Heo 14476183c009STejun Heo if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || 14486183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->entry) && 14496183c009STejun Heo (worker->hentry.next || worker->hentry.pprev))) 14506183c009STejun Heo return; 1451c8e55f36STejun Heo 1452cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1453cb444766STejun Heo worker->flags |= WORKER_IDLE; 1454bd7bdd43STejun Heo pool->nr_idle++; 1455e22bee78STejun Heo worker->last_active = jiffies; 1456c8e55f36STejun Heo 1457c8e55f36STejun Heo /* idle_list is LIFO */ 1458bd7bdd43STejun Heo list_add(&worker->entry, &pool->idle_list); 1459db7bccf4STejun Heo 146063d95a91STejun Heo if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 1461628c78e7STejun Heo mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 1462cb444766STejun Heo 1463544ecf31STejun Heo /* 1464706026c2STejun Heo * Sanity check nr_running. Because wq_unbind_fn() releases 1465d565ed63STejun Heo * pool->lock between setting %WORKER_UNBOUND and zapping 1466628c78e7STejun Heo * nr_running, the warning may trigger spuriously. Check iff 1467628c78e7STejun Heo * unbind is not in progress. 1468544ecf31STejun Heo */ 146924647570STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 1470bd7bdd43STejun Heo pool->nr_workers == pool->nr_idle && 1471e19e397aSTejun Heo atomic_read(&pool->nr_running)); 1472c8e55f36STejun Heo } 1473c8e55f36STejun Heo 1474c8e55f36STejun Heo /** 1475c8e55f36STejun Heo * worker_leave_idle - leave idle state 1476c8e55f36STejun Heo * @worker: worker which is leaving idle state 1477c8e55f36STejun Heo * 1478c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1479c8e55f36STejun Heo * 1480c8e55f36STejun Heo * LOCKING: 1481d565ed63STejun Heo * spin_lock_irq(pool->lock). 1482c8e55f36STejun Heo */ 1483c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1484c8e55f36STejun Heo { 1485bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1486c8e55f36STejun Heo 14876183c009STejun Heo if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) 14886183c009STejun Heo return; 1489d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1490bd7bdd43STejun Heo pool->nr_idle--; 1491c8e55f36STejun Heo list_del_init(&worker->entry); 1492c8e55f36STejun Heo } 1493c8e55f36STejun Heo 1494e22bee78STejun Heo /** 1495f36dc67bSLai Jiangshan * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it 1496f36dc67bSLai Jiangshan * @pool: target worker_pool 1497f36dc67bSLai Jiangshan * 1498f36dc67bSLai Jiangshan * Bind %current to the cpu of @pool if it is associated and lock @pool. 1499e22bee78STejun Heo * 1500e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1501e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1502e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1503e22bee78STejun Heo * guaranteed to execute on the cpu. 1504e22bee78STejun Heo * 1505f5faa077SLai Jiangshan * This function is to be used by unbound workers and rescuers to bind 1506e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1507e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1508e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1509706026c2STejun Heo * verbatim as it's best effort and blocking and pool may be 1510e22bee78STejun Heo * [dis]associated in the meantime. 1511e22bee78STejun Heo * 1512706026c2STejun Heo * This function tries set_cpus_allowed() and locks pool and verifies the 151324647570STejun Heo * binding against %POOL_DISASSOCIATED which is set during 1514f2d5a0eeSTejun Heo * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker 1515f2d5a0eeSTejun Heo * enters idle state or fetches works without dropping lock, it can 1516f2d5a0eeSTejun Heo * guarantee the scheduling requirement described in the first paragraph. 1517e22bee78STejun Heo * 1518e22bee78STejun Heo * CONTEXT: 1519d565ed63STejun Heo * Might sleep. Called without any lock but returns with pool->lock 1520e22bee78STejun Heo * held. 1521e22bee78STejun Heo * 1522e22bee78STejun Heo * RETURNS: 1523706026c2STejun Heo * %true if the associated pool is online (@worker is successfully 1524e22bee78STejun Heo * bound), %false if offline. 1525e22bee78STejun Heo */ 1526f36dc67bSLai Jiangshan static bool worker_maybe_bind_and_lock(struct worker_pool *pool) 1527d565ed63STejun Heo __acquires(&pool->lock) 1528e22bee78STejun Heo { 1529e22bee78STejun Heo while (true) { 1530e22bee78STejun Heo /* 1531e22bee78STejun Heo * The following call may fail, succeed or succeed 1532e22bee78STejun Heo * without actually migrating the task to the cpu if 1533e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 153424647570STejun Heo * against POOL_DISASSOCIATED. 1535e22bee78STejun Heo */ 153624647570STejun Heo if (!(pool->flags & POOL_DISASSOCIATED)) 1537f5faa077SLai Jiangshan set_cpus_allowed_ptr(current, get_cpu_mask(pool->cpu)); 1538e22bee78STejun Heo 1539d565ed63STejun Heo spin_lock_irq(&pool->lock); 154024647570STejun Heo if (pool->flags & POOL_DISASSOCIATED) 1541e22bee78STejun Heo return false; 1542f5faa077SLai Jiangshan if (task_cpu(current) == pool->cpu && 1543e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1544ec22ca5eSTejun Heo get_cpu_mask(pool->cpu))) 1545e22bee78STejun Heo return true; 1546d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1547e22bee78STejun Heo 15485035b20fSTejun Heo /* 15495035b20fSTejun Heo * We've raced with CPU hot[un]plug. Give it a breather 15505035b20fSTejun Heo * and retry migration. cond_resched() is required here; 15515035b20fSTejun Heo * otherwise, we might deadlock against cpu_stop trying to 15525035b20fSTejun Heo * bring down the CPU on non-preemptive kernel. 15535035b20fSTejun Heo */ 1554e22bee78STejun Heo cpu_relax(); 15555035b20fSTejun Heo cond_resched(); 1556e22bee78STejun Heo } 1557e22bee78STejun Heo } 1558e22bee78STejun Heo 1559e22bee78STejun Heo /* 1560ea1abd61SLai Jiangshan * Rebind an idle @worker to its CPU. worker_thread() will test 15615f7dabfdSLai Jiangshan * list_empty(@worker->entry) before leaving idle and call this function. 156225511a47STejun Heo */ 156325511a47STejun Heo static void idle_worker_rebind(struct worker *worker) 156425511a47STejun Heo { 15655f7dabfdSLai Jiangshan /* CPU may go down again inbetween, clear UNBOUND only on success */ 1566f36dc67bSLai Jiangshan if (worker_maybe_bind_and_lock(worker->pool)) 15675f7dabfdSLai Jiangshan worker_clr_flags(worker, WORKER_UNBOUND); 156825511a47STejun Heo 1569ea1abd61SLai Jiangshan /* rebind complete, become available again */ 1570ea1abd61SLai Jiangshan list_add(&worker->entry, &worker->pool->idle_list); 1571d565ed63STejun Heo spin_unlock_irq(&worker->pool->lock); 157225511a47STejun Heo } 157325511a47STejun Heo 157425511a47STejun Heo /* 157525511a47STejun Heo * Function for @worker->rebind.work used to rebind unbound busy workers to 1576403c821dSTejun Heo * the associated cpu which is coming back online. This is scheduled by 1577403c821dSTejun Heo * cpu up but can race with other cpu hotplug operations and may be 1578403c821dSTejun Heo * executed twice without intervening cpu down. 1579e22bee78STejun Heo */ 158025511a47STejun Heo static void busy_worker_rebind_fn(struct work_struct *work) 1581e22bee78STejun Heo { 1582e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1583e22bee78STejun Heo 1584f36dc67bSLai Jiangshan if (worker_maybe_bind_and_lock(worker->pool)) 1585eab6d828SLai Jiangshan worker_clr_flags(worker, WORKER_UNBOUND); 1586e22bee78STejun Heo 1587d565ed63STejun Heo spin_unlock_irq(&worker->pool->lock); 1588e22bee78STejun Heo } 1589e22bee78STejun Heo 159025511a47STejun Heo /** 159194cf58bbSTejun Heo * rebind_workers - rebind all workers of a pool to the associated CPU 159294cf58bbSTejun Heo * @pool: pool of interest 159325511a47STejun Heo * 159494cf58bbSTejun Heo * @pool->cpu is coming online. Rebind all workers to the CPU. Rebinding 159525511a47STejun Heo * is different for idle and busy ones. 159625511a47STejun Heo * 1597ea1abd61SLai Jiangshan * Idle ones will be removed from the idle_list and woken up. They will 1598ea1abd61SLai Jiangshan * add themselves back after completing rebind. This ensures that the 1599ea1abd61SLai Jiangshan * idle_list doesn't contain any unbound workers when re-bound busy workers 1600ea1abd61SLai Jiangshan * try to perform local wake-ups for concurrency management. 160125511a47STejun Heo * 1602ea1abd61SLai Jiangshan * Busy workers can rebind after they finish their current work items. 1603ea1abd61SLai Jiangshan * Queueing the rebind work item at the head of the scheduled list is 1604ea1abd61SLai Jiangshan * enough. Note that nr_running will be properly bumped as busy workers 1605ea1abd61SLai Jiangshan * rebind. 160625511a47STejun Heo * 1607ea1abd61SLai Jiangshan * On return, all non-manager workers are scheduled for rebind - see 1608ea1abd61SLai Jiangshan * manage_workers() for the manager special case. Any idle worker 1609ea1abd61SLai Jiangshan * including the manager will not appear on @idle_list until rebind is 1610ea1abd61SLai Jiangshan * complete, making local wake-ups safe. 161125511a47STejun Heo */ 161294cf58bbSTejun Heo static void rebind_workers(struct worker_pool *pool) 161325511a47STejun Heo { 1614ea1abd61SLai Jiangshan struct worker *worker, *n; 161525511a47STejun Heo int i; 161625511a47STejun Heo 1617b2eb83d1SLai Jiangshan lockdep_assert_held(&pool->assoc_mutex); 1618d565ed63STejun Heo lockdep_assert_held(&pool->lock); 161925511a47STejun Heo 16205f7dabfdSLai Jiangshan /* dequeue and kick idle ones */ 1621ea1abd61SLai Jiangshan list_for_each_entry_safe(worker, n, &pool->idle_list, entry) { 1622ea1abd61SLai Jiangshan /* 162394cf58bbSTejun Heo * idle workers should be off @pool->idle_list until rebind 162494cf58bbSTejun Heo * is complete to avoid receiving premature local wake-ups. 1625ea1abd61SLai Jiangshan */ 1626ea1abd61SLai Jiangshan list_del_init(&worker->entry); 162725511a47STejun Heo 162825511a47STejun Heo /* 162994cf58bbSTejun Heo * worker_thread() will see the above dequeuing and call 163094cf58bbSTejun Heo * idle_worker_rebind(). 163125511a47STejun Heo */ 163225511a47STejun Heo wake_up_process(worker->task); 163325511a47STejun Heo } 163425511a47STejun Heo 1635ea1abd61SLai Jiangshan /* rebind busy workers */ 1636b67bfe0dSSasha Levin for_each_busy_worker(worker, i, pool) { 163725511a47STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 1638e2b6a6d5SJoonsoo Kim struct workqueue_struct *wq; 163925511a47STejun Heo 164025511a47STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 164125511a47STejun Heo work_data_bits(rebind_work))) 164225511a47STejun Heo continue; 164325511a47STejun Heo 164425511a47STejun Heo debug_work_activate(rebind_work); 164590beca5dSTejun Heo 164690beca5dSTejun Heo /* 164794cf58bbSTejun Heo * wq doesn't really matter but let's keep @worker->pool 1648112202d9STejun Heo * and @pwq->pool consistent for sanity. 164990beca5dSTejun Heo */ 1650e34cdddbSTejun Heo if (std_worker_pool_pri(worker->pool)) 1651e2b6a6d5SJoonsoo Kim wq = system_highpri_wq; 1652e2b6a6d5SJoonsoo Kim else 1653e2b6a6d5SJoonsoo Kim wq = system_wq; 1654ec58815aSTejun Heo 1655112202d9STejun Heo insert_work(get_pwq(pool->cpu, wq), rebind_work, 165625511a47STejun Heo worker->scheduled.next, 165725511a47STejun Heo work_color_to_flags(WORK_NO_COLOR)); 1658ec58815aSTejun Heo } 165925511a47STejun Heo } 166025511a47STejun Heo 1661c34056a3STejun Heo static struct worker *alloc_worker(void) 1662c34056a3STejun Heo { 1663c34056a3STejun Heo struct worker *worker; 1664c34056a3STejun Heo 1665c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1666c8e55f36STejun Heo if (worker) { 1667c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1668affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 166925511a47STejun Heo INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn); 1670e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1671e22bee78STejun Heo worker->flags = WORKER_PREP; 1672c8e55f36STejun Heo } 1673c34056a3STejun Heo return worker; 1674c34056a3STejun Heo } 1675c34056a3STejun Heo 1676c34056a3STejun Heo /** 1677c34056a3STejun Heo * create_worker - create a new workqueue worker 167863d95a91STejun Heo * @pool: pool the new worker will belong to 1679c34056a3STejun Heo * 168063d95a91STejun Heo * Create a new worker which is bound to @pool. The returned worker 1681c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1682c34056a3STejun Heo * destroy_worker(). 1683c34056a3STejun Heo * 1684c34056a3STejun Heo * CONTEXT: 1685c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1686c34056a3STejun Heo * 1687c34056a3STejun Heo * RETURNS: 1688c34056a3STejun Heo * Pointer to the newly created worker. 1689c34056a3STejun Heo */ 1690bc2ae0f5STejun Heo static struct worker *create_worker(struct worker_pool *pool) 1691c34056a3STejun Heo { 1692e34cdddbSTejun Heo const char *pri = std_worker_pool_pri(pool) ? "H" : ""; 1693c34056a3STejun Heo struct worker *worker = NULL; 1694f3421797STejun Heo int id = -1; 1695c34056a3STejun Heo 1696d565ed63STejun Heo spin_lock_irq(&pool->lock); 1697bd7bdd43STejun Heo while (ida_get_new(&pool->worker_ida, &id)) { 1698d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1699bd7bdd43STejun Heo if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL)) 1700c34056a3STejun Heo goto fail; 1701d565ed63STejun Heo spin_lock_irq(&pool->lock); 1702c34056a3STejun Heo } 1703d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1704c34056a3STejun Heo 1705c34056a3STejun Heo worker = alloc_worker(); 1706c34056a3STejun Heo if (!worker) 1707c34056a3STejun Heo goto fail; 1708c34056a3STejun Heo 1709bd7bdd43STejun Heo worker->pool = pool; 1710c34056a3STejun Heo worker->id = id; 1711c34056a3STejun Heo 1712ec22ca5eSTejun Heo if (pool->cpu != WORK_CPU_UNBOUND) 171394dcf29aSEric Dumazet worker->task = kthread_create_on_node(worker_thread, 1714ec22ca5eSTejun Heo worker, cpu_to_node(pool->cpu), 1715d84ff051STejun Heo "kworker/%d:%d%s", pool->cpu, id, pri); 1716f3421797STejun Heo else 1717f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 17183270476aSTejun Heo "kworker/u:%d%s", id, pri); 1719c34056a3STejun Heo if (IS_ERR(worker->task)) 1720c34056a3STejun Heo goto fail; 1721c34056a3STejun Heo 1722e34cdddbSTejun Heo if (std_worker_pool_pri(pool)) 17233270476aSTejun Heo set_user_nice(worker->task, HIGHPRI_NICE_LEVEL); 17243270476aSTejun Heo 1725db7bccf4STejun Heo /* 1726bc2ae0f5STejun Heo * Determine CPU binding of the new worker depending on 172724647570STejun Heo * %POOL_DISASSOCIATED. The caller is responsible for ensuring the 1728bc2ae0f5STejun Heo * flag remains stable across this function. See the comments 1729bc2ae0f5STejun Heo * above the flag definition for details. 1730bc2ae0f5STejun Heo * 1731bc2ae0f5STejun Heo * As an unbound worker may later become a regular one if CPU comes 1732bc2ae0f5STejun Heo * online, make sure every worker has %PF_THREAD_BOUND set. 1733db7bccf4STejun Heo */ 173424647570STejun Heo if (!(pool->flags & POOL_DISASSOCIATED)) { 1735ec22ca5eSTejun Heo kthread_bind(worker->task, pool->cpu); 1736bc2ae0f5STejun Heo } else { 1737db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1738f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1739f3421797STejun Heo } 1740c34056a3STejun Heo 1741c34056a3STejun Heo return worker; 1742c34056a3STejun Heo fail: 1743c34056a3STejun Heo if (id >= 0) { 1744d565ed63STejun Heo spin_lock_irq(&pool->lock); 1745bd7bdd43STejun Heo ida_remove(&pool->worker_ida, id); 1746d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1747c34056a3STejun Heo } 1748c34056a3STejun Heo kfree(worker); 1749c34056a3STejun Heo return NULL; 1750c34056a3STejun Heo } 1751c34056a3STejun Heo 1752c34056a3STejun Heo /** 1753c34056a3STejun Heo * start_worker - start a newly created worker 1754c34056a3STejun Heo * @worker: worker to start 1755c34056a3STejun Heo * 1756706026c2STejun Heo * Make the pool aware of @worker and start it. 1757c34056a3STejun Heo * 1758c34056a3STejun Heo * CONTEXT: 1759d565ed63STejun Heo * spin_lock_irq(pool->lock). 1760c34056a3STejun Heo */ 1761c34056a3STejun Heo static void start_worker(struct worker *worker) 1762c34056a3STejun Heo { 1763cb444766STejun Heo worker->flags |= WORKER_STARTED; 1764bd7bdd43STejun Heo worker->pool->nr_workers++; 1765c8e55f36STejun Heo worker_enter_idle(worker); 1766c34056a3STejun Heo wake_up_process(worker->task); 1767c34056a3STejun Heo } 1768c34056a3STejun Heo 1769c34056a3STejun Heo /** 1770c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1771c34056a3STejun Heo * @worker: worker to be destroyed 1772c34056a3STejun Heo * 1773706026c2STejun Heo * Destroy @worker and adjust @pool stats accordingly. 1774c8e55f36STejun Heo * 1775c8e55f36STejun Heo * CONTEXT: 1776d565ed63STejun Heo * spin_lock_irq(pool->lock) which is released and regrabbed. 1777c34056a3STejun Heo */ 1778c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1779c34056a3STejun Heo { 1780bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1781c34056a3STejun Heo int id = worker->id; 1782c34056a3STejun Heo 1783c34056a3STejun Heo /* sanity check frenzy */ 17846183c009STejun Heo if (WARN_ON(worker->current_work) || 17856183c009STejun Heo WARN_ON(!list_empty(&worker->scheduled))) 17866183c009STejun Heo return; 1787c34056a3STejun Heo 1788c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1789bd7bdd43STejun Heo pool->nr_workers--; 1790c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1791bd7bdd43STejun Heo pool->nr_idle--; 1792c8e55f36STejun Heo 1793c8e55f36STejun Heo list_del_init(&worker->entry); 1794cb444766STejun Heo worker->flags |= WORKER_DIE; 1795c8e55f36STejun Heo 1796d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1797c8e55f36STejun Heo 1798c34056a3STejun Heo kthread_stop(worker->task); 1799c34056a3STejun Heo kfree(worker); 1800c34056a3STejun Heo 1801d565ed63STejun Heo spin_lock_irq(&pool->lock); 1802bd7bdd43STejun Heo ida_remove(&pool->worker_ida, id); 1803c34056a3STejun Heo } 1804c34056a3STejun Heo 180563d95a91STejun Heo static void idle_worker_timeout(unsigned long __pool) 1806e22bee78STejun Heo { 180763d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 1808e22bee78STejun Heo 1809d565ed63STejun Heo spin_lock_irq(&pool->lock); 1810e22bee78STejun Heo 181163d95a91STejun Heo if (too_many_workers(pool)) { 1812e22bee78STejun Heo struct worker *worker; 1813e22bee78STejun Heo unsigned long expires; 1814e22bee78STejun Heo 1815e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 181663d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 1817e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1818e22bee78STejun Heo 1819e22bee78STejun Heo if (time_before(jiffies, expires)) 182063d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 1821e22bee78STejun Heo else { 1822e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 182311ebea50STejun Heo pool->flags |= POOL_MANAGE_WORKERS; 182463d95a91STejun Heo wake_up_worker(pool); 1825e22bee78STejun Heo } 1826e22bee78STejun Heo } 1827e22bee78STejun Heo 1828d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1829e22bee78STejun Heo } 1830e22bee78STejun Heo 1831493a1724STejun Heo static void send_mayday(struct work_struct *work) 1832e22bee78STejun Heo { 1833112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 1834112202d9STejun Heo struct workqueue_struct *wq = pwq->wq; 1835493a1724STejun Heo 1836493a1724STejun Heo lockdep_assert_held(&workqueue_lock); 1837e22bee78STejun Heo 1838e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1839493a1724STejun Heo return; 1840e22bee78STejun Heo 1841e22bee78STejun Heo /* mayday mayday mayday */ 1842493a1724STejun Heo if (list_empty(&pwq->mayday_node)) { 1843493a1724STejun Heo list_add_tail(&pwq->mayday_node, &wq->maydays); 1844e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1845493a1724STejun Heo } 1846e22bee78STejun Heo } 1847e22bee78STejun Heo 1848706026c2STejun Heo static void pool_mayday_timeout(unsigned long __pool) 1849e22bee78STejun Heo { 185063d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 1851e22bee78STejun Heo struct work_struct *work; 1852e22bee78STejun Heo 1853493a1724STejun Heo spin_lock_irq(&workqueue_lock); /* for wq->maydays */ 1854493a1724STejun Heo spin_lock(&pool->lock); 1855e22bee78STejun Heo 185663d95a91STejun Heo if (need_to_create_worker(pool)) { 1857e22bee78STejun Heo /* 1858e22bee78STejun Heo * We've been trying to create a new worker but 1859e22bee78STejun Heo * haven't been successful. We might be hitting an 1860e22bee78STejun Heo * allocation deadlock. Send distress signals to 1861e22bee78STejun Heo * rescuers. 1862e22bee78STejun Heo */ 186363d95a91STejun Heo list_for_each_entry(work, &pool->worklist, entry) 1864e22bee78STejun Heo send_mayday(work); 1865e22bee78STejun Heo } 1866e22bee78STejun Heo 1867493a1724STejun Heo spin_unlock(&pool->lock); 1868493a1724STejun Heo spin_unlock_irq(&workqueue_lock); 1869e22bee78STejun Heo 187063d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 1871e22bee78STejun Heo } 1872e22bee78STejun Heo 1873e22bee78STejun Heo /** 1874e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 187563d95a91STejun Heo * @pool: pool to create a new worker for 1876e22bee78STejun Heo * 187763d95a91STejun Heo * Create a new worker for @pool if necessary. @pool is guaranteed to 1878e22bee78STejun Heo * have at least one idle worker on return from this function. If 1879e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 188063d95a91STejun Heo * sent to all rescuers with works scheduled on @pool to resolve 1881e22bee78STejun Heo * possible allocation deadlock. 1882e22bee78STejun Heo * 1883e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1884e22bee78STejun Heo * may_start_working() true. 1885e22bee78STejun Heo * 1886e22bee78STejun Heo * LOCKING: 1887d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 1888e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1889e22bee78STejun Heo * manager. 1890e22bee78STejun Heo * 1891e22bee78STejun Heo * RETURNS: 1892d565ed63STejun Heo * false if no action was taken and pool->lock stayed locked, true 1893e22bee78STejun Heo * otherwise. 1894e22bee78STejun Heo */ 189563d95a91STejun Heo static bool maybe_create_worker(struct worker_pool *pool) 1896d565ed63STejun Heo __releases(&pool->lock) 1897d565ed63STejun Heo __acquires(&pool->lock) 1898e22bee78STejun Heo { 189963d95a91STejun Heo if (!need_to_create_worker(pool)) 1900e22bee78STejun Heo return false; 1901e22bee78STejun Heo restart: 1902d565ed63STejun Heo spin_unlock_irq(&pool->lock); 19039f9c2364STejun Heo 1904e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 190563d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1906e22bee78STejun Heo 1907e22bee78STejun Heo while (true) { 1908e22bee78STejun Heo struct worker *worker; 1909e22bee78STejun Heo 1910bc2ae0f5STejun Heo worker = create_worker(pool); 1911e22bee78STejun Heo if (worker) { 191263d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 1913d565ed63STejun Heo spin_lock_irq(&pool->lock); 1914e22bee78STejun Heo start_worker(worker); 19156183c009STejun Heo if (WARN_ON_ONCE(need_to_create_worker(pool))) 19166183c009STejun Heo goto restart; 1917e22bee78STejun Heo return true; 1918e22bee78STejun Heo } 1919e22bee78STejun Heo 192063d95a91STejun Heo if (!need_to_create_worker(pool)) 1921e22bee78STejun Heo break; 1922e22bee78STejun Heo 1923e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1924e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 19259f9c2364STejun Heo 192663d95a91STejun Heo if (!need_to_create_worker(pool)) 1927e22bee78STejun Heo break; 1928e22bee78STejun Heo } 1929e22bee78STejun Heo 193063d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 1931d565ed63STejun Heo spin_lock_irq(&pool->lock); 193263d95a91STejun Heo if (need_to_create_worker(pool)) 1933e22bee78STejun Heo goto restart; 1934e22bee78STejun Heo return true; 1935e22bee78STejun Heo } 1936e22bee78STejun Heo 1937e22bee78STejun Heo /** 1938e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 193963d95a91STejun Heo * @pool: pool to destroy workers for 1940e22bee78STejun Heo * 194163d95a91STejun Heo * Destroy @pool workers which have been idle for longer than 1942e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1943e22bee78STejun Heo * 1944e22bee78STejun Heo * LOCKING: 1945d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 1946e22bee78STejun Heo * multiple times. Called only from manager. 1947e22bee78STejun Heo * 1948e22bee78STejun Heo * RETURNS: 1949d565ed63STejun Heo * false if no action was taken and pool->lock stayed locked, true 1950e22bee78STejun Heo * otherwise. 1951e22bee78STejun Heo */ 195263d95a91STejun Heo static bool maybe_destroy_workers(struct worker_pool *pool) 1953e22bee78STejun Heo { 1954e22bee78STejun Heo bool ret = false; 1955e22bee78STejun Heo 195663d95a91STejun Heo while (too_many_workers(pool)) { 1957e22bee78STejun Heo struct worker *worker; 1958e22bee78STejun Heo unsigned long expires; 1959e22bee78STejun Heo 196063d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 1961e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1962e22bee78STejun Heo 1963e22bee78STejun Heo if (time_before(jiffies, expires)) { 196463d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 1965e22bee78STejun Heo break; 1966e22bee78STejun Heo } 1967e22bee78STejun Heo 1968e22bee78STejun Heo destroy_worker(worker); 1969e22bee78STejun Heo ret = true; 1970e22bee78STejun Heo } 1971e22bee78STejun Heo 1972e22bee78STejun Heo return ret; 1973e22bee78STejun Heo } 1974e22bee78STejun Heo 1975e22bee78STejun Heo /** 1976e22bee78STejun Heo * manage_workers - manage worker pool 1977e22bee78STejun Heo * @worker: self 1978e22bee78STejun Heo * 1979706026c2STejun Heo * Assume the manager role and manage the worker pool @worker belongs 1980e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 1981706026c2STejun Heo * pool. The exclusion is handled automatically by this function. 1982e22bee78STejun Heo * 1983e22bee78STejun Heo * The caller can safely start processing works on false return. On 1984e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 1985e22bee78STejun Heo * and may_start_working() is true. 1986e22bee78STejun Heo * 1987e22bee78STejun Heo * CONTEXT: 1988d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 1989e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 1990e22bee78STejun Heo * 1991e22bee78STejun Heo * RETURNS: 1992d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 1993d565ed63STejun Heo * multiple times. Does GFP_KERNEL allocations. 1994e22bee78STejun Heo */ 1995e22bee78STejun Heo static bool manage_workers(struct worker *worker) 1996e22bee78STejun Heo { 199763d95a91STejun Heo struct worker_pool *pool = worker->pool; 1998e22bee78STejun Heo bool ret = false; 1999e22bee78STejun Heo 2000ee378aa4SLai Jiangshan if (pool->flags & POOL_MANAGING_WORKERS) 2001e22bee78STejun Heo return ret; 2002e22bee78STejun Heo 2003552a37e9SLai Jiangshan pool->flags |= POOL_MANAGING_WORKERS; 2004ee378aa4SLai Jiangshan 2005ee378aa4SLai Jiangshan /* 2006ee378aa4SLai Jiangshan * To simplify both worker management and CPU hotplug, hold off 2007ee378aa4SLai Jiangshan * management while hotplug is in progress. CPU hotplug path can't 2008ee378aa4SLai Jiangshan * grab %POOL_MANAGING_WORKERS to achieve this because that can 2009ee378aa4SLai Jiangshan * lead to idle worker depletion (all become busy thinking someone 2010ee378aa4SLai Jiangshan * else is managing) which in turn can result in deadlock under 2011b2eb83d1SLai Jiangshan * extreme circumstances. Use @pool->assoc_mutex to synchronize 2012ee378aa4SLai Jiangshan * manager against CPU hotplug. 2013ee378aa4SLai Jiangshan * 2014b2eb83d1SLai Jiangshan * assoc_mutex would always be free unless CPU hotplug is in 2015d565ed63STejun Heo * progress. trylock first without dropping @pool->lock. 2016ee378aa4SLai Jiangshan */ 2017b2eb83d1SLai Jiangshan if (unlikely(!mutex_trylock(&pool->assoc_mutex))) { 2018d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2019b2eb83d1SLai Jiangshan mutex_lock(&pool->assoc_mutex); 2020ee378aa4SLai Jiangshan /* 2021ee378aa4SLai Jiangshan * CPU hotplug could have happened while we were waiting 2022b2eb83d1SLai Jiangshan * for assoc_mutex. Hotplug itself can't handle us 2023ee378aa4SLai Jiangshan * because manager isn't either on idle or busy list, and 2024706026c2STejun Heo * @pool's state and ours could have deviated. 2025ee378aa4SLai Jiangshan * 2026b2eb83d1SLai Jiangshan * As hotplug is now excluded via assoc_mutex, we can 2027ee378aa4SLai Jiangshan * simply try to bind. It will succeed or fail depending 2028706026c2STejun Heo * on @pool's current state. Try it and adjust 2029ee378aa4SLai Jiangshan * %WORKER_UNBOUND accordingly. 2030ee378aa4SLai Jiangshan */ 2031f36dc67bSLai Jiangshan if (worker_maybe_bind_and_lock(pool)) 2032ee378aa4SLai Jiangshan worker->flags &= ~WORKER_UNBOUND; 2033ee378aa4SLai Jiangshan else 2034ee378aa4SLai Jiangshan worker->flags |= WORKER_UNBOUND; 2035ee378aa4SLai Jiangshan 2036ee378aa4SLai Jiangshan ret = true; 2037ee378aa4SLai Jiangshan } 2038ee378aa4SLai Jiangshan 203911ebea50STejun Heo pool->flags &= ~POOL_MANAGE_WORKERS; 2040e22bee78STejun Heo 2041e22bee78STejun Heo /* 2042e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 2043e22bee78STejun Heo * on return. 2044e22bee78STejun Heo */ 204563d95a91STejun Heo ret |= maybe_destroy_workers(pool); 204663d95a91STejun Heo ret |= maybe_create_worker(pool); 2047e22bee78STejun Heo 2048552a37e9SLai Jiangshan pool->flags &= ~POOL_MANAGING_WORKERS; 2049b2eb83d1SLai Jiangshan mutex_unlock(&pool->assoc_mutex); 2050e22bee78STejun Heo return ret; 2051e22bee78STejun Heo } 2052e22bee78STejun Heo 2053a62428c0STejun Heo /** 2054a62428c0STejun Heo * process_one_work - process single work 2055c34056a3STejun Heo * @worker: self 2056a62428c0STejun Heo * @work: work to process 2057a62428c0STejun Heo * 2058a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 2059a62428c0STejun Heo * process a single work including synchronization against and 2060a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 2061a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 2062a62428c0STejun Heo * call this function to process a work. 2063a62428c0STejun Heo * 2064a62428c0STejun Heo * CONTEXT: 2065d565ed63STejun Heo * spin_lock_irq(pool->lock) which is released and regrabbed. 2066a62428c0STejun Heo */ 2067c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 2068d565ed63STejun Heo __releases(&pool->lock) 2069d565ed63STejun Heo __acquires(&pool->lock) 20701da177e4SLinus Torvalds { 2071112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2072bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2073112202d9STejun Heo bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; 207473f53c4aSTejun Heo int work_color; 20757e11629dSTejun Heo struct worker *collision; 20764e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 20774e6045f1SJohannes Berg /* 2078a62428c0STejun Heo * It is permissible to free the struct work_struct from 2079a62428c0STejun Heo * inside the function that is called from it, this we need to 2080a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 2081a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 2082a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 20834e6045f1SJohannes Berg */ 20844d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 20854d82a1deSPeter Zijlstra 20864d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 20874e6045f1SJohannes Berg #endif 20886fec10a1STejun Heo /* 20896fec10a1STejun Heo * Ensure we're on the correct CPU. DISASSOCIATED test is 20906fec10a1STejun Heo * necessary to avoid spurious warnings from rescuers servicing the 209124647570STejun Heo * unbound or a disassociated pool. 20926fec10a1STejun Heo */ 20935f7dabfdSLai Jiangshan WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && 209424647570STejun Heo !(pool->flags & POOL_DISASSOCIATED) && 2095ec22ca5eSTejun Heo raw_smp_processor_id() != pool->cpu); 209625511a47STejun Heo 20977e11629dSTejun Heo /* 20987e11629dSTejun Heo * A single work shouldn't be executed concurrently by 20997e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 21007e11629dSTejun Heo * already processing the work. If so, defer the work to the 21017e11629dSTejun Heo * currently executing one. 21027e11629dSTejun Heo */ 2103c9e7cf27STejun Heo collision = find_worker_executing_work(pool, work); 21047e11629dSTejun Heo if (unlikely(collision)) { 21057e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 21067e11629dSTejun Heo return; 21077e11629dSTejun Heo } 21081da177e4SLinus Torvalds 21098930cabaSTejun Heo /* claim and dequeue */ 21101da177e4SLinus Torvalds debug_work_deactivate(work); 2111c9e7cf27STejun Heo hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); 2112c34056a3STejun Heo worker->current_work = work; 2113a2c1c57bSTejun Heo worker->current_func = work->func; 2114112202d9STejun Heo worker->current_pwq = pwq; 211573f53c4aSTejun Heo work_color = get_work_color(work); 21167a22ad75STejun Heo 2117a62428c0STejun Heo list_del_init(&work->entry); 2118a62428c0STejun Heo 2119649027d7STejun Heo /* 2120fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 2121fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 2122fb0e7bebSTejun Heo */ 2123fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2124fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 2125fb0e7bebSTejun Heo 2126974271c4STejun Heo /* 2127d565ed63STejun Heo * Unbound pool isn't concurrency managed and work items should be 2128974271c4STejun Heo * executed ASAP. Wake up another worker if necessary. 2129974271c4STejun Heo */ 213063d95a91STejun Heo if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) 213163d95a91STejun Heo wake_up_worker(pool); 2132974271c4STejun Heo 21338930cabaSTejun Heo /* 21347c3eed5cSTejun Heo * Record the last pool and clear PENDING which should be the last 2135d565ed63STejun Heo * update to @work. Also, do this inside @pool->lock so that 213623657bb1STejun Heo * PENDING and queued state changes happen together while IRQ is 213723657bb1STejun Heo * disabled. 21388930cabaSTejun Heo */ 21397c3eed5cSTejun Heo set_work_pool_and_clear_pending(work, pool->id); 21401da177e4SLinus Torvalds 2141d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2142365970a1SDavid Howells 2143112202d9STejun Heo lock_map_acquire_read(&pwq->wq->lockdep_map); 21443295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 2145e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 2146a2c1c57bSTejun Heo worker->current_func(work); 2147e36c886aSArjan van de Ven /* 2148e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 2149e36c886aSArjan van de Ven * point will only record its address. 2150e36c886aSArjan van de Ven */ 2151e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 21523295f0efSIngo Molnar lock_map_release(&lockdep_map); 2153112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 21541da177e4SLinus Torvalds 2155d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 2156044c782cSValentin Ilie pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" 2157044c782cSValentin Ilie " last function: %pf\n", 2158a2c1c57bSTejun Heo current->comm, preempt_count(), task_pid_nr(current), 2159a2c1c57bSTejun Heo worker->current_func); 2160d5abe669SPeter Zijlstra debug_show_held_locks(current); 2161d5abe669SPeter Zijlstra dump_stack(); 2162d5abe669SPeter Zijlstra } 2163d5abe669SPeter Zijlstra 2164d565ed63STejun Heo spin_lock_irq(&pool->lock); 2165a62428c0STejun Heo 2166fb0e7bebSTejun Heo /* clear cpu intensive status */ 2167fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2168fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 2169fb0e7bebSTejun Heo 2170a62428c0STejun Heo /* we're done with it, release */ 217142f8570fSSasha Levin hash_del(&worker->hentry); 2172c34056a3STejun Heo worker->current_work = NULL; 2173a2c1c57bSTejun Heo worker->current_func = NULL; 2174112202d9STejun Heo worker->current_pwq = NULL; 2175112202d9STejun Heo pwq_dec_nr_in_flight(pwq, work_color); 21761da177e4SLinus Torvalds } 21771da177e4SLinus Torvalds 2178affee4b2STejun Heo /** 2179affee4b2STejun Heo * process_scheduled_works - process scheduled works 2180affee4b2STejun Heo * @worker: self 2181affee4b2STejun Heo * 2182affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 2183affee4b2STejun Heo * may change while processing a work, so this function repeatedly 2184affee4b2STejun Heo * fetches a work from the top and executes it. 2185affee4b2STejun Heo * 2186affee4b2STejun Heo * CONTEXT: 2187d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2188affee4b2STejun Heo * multiple times. 2189affee4b2STejun Heo */ 2190affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 21911da177e4SLinus Torvalds { 2192affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 2193affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 2194a62428c0STejun Heo struct work_struct, entry); 2195c34056a3STejun Heo process_one_work(worker, work); 2196a62428c0STejun Heo } 21971da177e4SLinus Torvalds } 21981da177e4SLinus Torvalds 21994690c4abSTejun Heo /** 22004690c4abSTejun Heo * worker_thread - the worker thread function 2201c34056a3STejun Heo * @__worker: self 22024690c4abSTejun Heo * 2203706026c2STejun Heo * The worker thread function. There are NR_CPU_WORKER_POOLS dynamic pools 2204706026c2STejun Heo * of these per each cpu. These workers process all works regardless of 2205e22bee78STejun Heo * their specific target workqueue. The only exception is works which 2206e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 2207e22bee78STejun Heo * rescuer_thread(). 22084690c4abSTejun Heo */ 2209c34056a3STejun Heo static int worker_thread(void *__worker) 22101da177e4SLinus Torvalds { 2211c34056a3STejun Heo struct worker *worker = __worker; 2212bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 22131da177e4SLinus Torvalds 2214e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 2215e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 2216c8e55f36STejun Heo woke_up: 2217d565ed63STejun Heo spin_lock_irq(&pool->lock); 2218affee4b2STejun Heo 22195f7dabfdSLai Jiangshan /* we are off idle list if destruction or rebind is requested */ 22205f7dabfdSLai Jiangshan if (unlikely(list_empty(&worker->entry))) { 2221d565ed63STejun Heo spin_unlock_irq(&pool->lock); 222225511a47STejun Heo 22235f7dabfdSLai Jiangshan /* if DIE is set, destruction is requested */ 222425511a47STejun Heo if (worker->flags & WORKER_DIE) { 2225e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 2226c8e55f36STejun Heo return 0; 2227c8e55f36STejun Heo } 2228c8e55f36STejun Heo 22295f7dabfdSLai Jiangshan /* otherwise, rebind */ 223025511a47STejun Heo idle_worker_rebind(worker); 223125511a47STejun Heo goto woke_up; 223225511a47STejun Heo } 223325511a47STejun Heo 2234c8e55f36STejun Heo worker_leave_idle(worker); 2235db7bccf4STejun Heo recheck: 2236e22bee78STejun Heo /* no more worker necessary? */ 223763d95a91STejun Heo if (!need_more_worker(pool)) 2238e22bee78STejun Heo goto sleep; 2239e22bee78STejun Heo 2240e22bee78STejun Heo /* do we need to manage? */ 224163d95a91STejun Heo if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 2242e22bee78STejun Heo goto recheck; 2243e22bee78STejun Heo 2244c8e55f36STejun Heo /* 2245c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 2246c8e55f36STejun Heo * preparing to process a work or actually processing it. 2247c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 2248c8e55f36STejun Heo */ 22496183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->scheduled)); 2250c8e55f36STejun Heo 2251e22bee78STejun Heo /* 2252e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 2253e22bee78STejun Heo * at least one idle worker or that someone else has already 2254e22bee78STejun Heo * assumed the manager role. 2255e22bee78STejun Heo */ 2256e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 2257e22bee78STejun Heo 2258e22bee78STejun Heo do { 2259affee4b2STejun Heo struct work_struct *work = 2260bd7bdd43STejun Heo list_first_entry(&pool->worklist, 2261affee4b2STejun Heo struct work_struct, entry); 2262affee4b2STejun Heo 2263c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 2264affee4b2STejun Heo /* optimization path, not strictly necessary */ 2265affee4b2STejun Heo process_one_work(worker, work); 2266affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 2267affee4b2STejun Heo process_scheduled_works(worker); 2268affee4b2STejun Heo } else { 2269c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 2270affee4b2STejun Heo process_scheduled_works(worker); 2271affee4b2STejun Heo } 227263d95a91STejun Heo } while (keep_working(pool)); 2273affee4b2STejun Heo 2274e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 2275d313dd85STejun Heo sleep: 227663d95a91STejun Heo if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) 2277e22bee78STejun Heo goto recheck; 2278d313dd85STejun Heo 2279c8e55f36STejun Heo /* 2280d565ed63STejun Heo * pool->lock is held and there's no work to process and no need to 2281d565ed63STejun Heo * manage, sleep. Workers are woken up only while holding 2282d565ed63STejun Heo * pool->lock or from local cpu, so setting the current state 2283d565ed63STejun Heo * before releasing pool->lock is enough to prevent losing any 2284d565ed63STejun Heo * event. 2285c8e55f36STejun Heo */ 2286c8e55f36STejun Heo worker_enter_idle(worker); 2287c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 2288d565ed63STejun Heo spin_unlock_irq(&pool->lock); 22891da177e4SLinus Torvalds schedule(); 2290c8e55f36STejun Heo goto woke_up; 22911da177e4SLinus Torvalds } 22921da177e4SLinus Torvalds 2293e22bee78STejun Heo /** 2294e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2295111c225aSTejun Heo * @__rescuer: self 2296e22bee78STejun Heo * 2297e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2298e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 2299e22bee78STejun Heo * 2300706026c2STejun Heo * Regular work processing on a pool may block trying to create a new 2301e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2302e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2303e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2304e22bee78STejun Heo * the problem rescuer solves. 2305e22bee78STejun Heo * 2306706026c2STejun Heo * When such condition is possible, the pool summons rescuers of all 2307706026c2STejun Heo * workqueues which have works queued on the pool and let them process 2308e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2309e22bee78STejun Heo * 2310e22bee78STejun Heo * This should happen rarely. 2311e22bee78STejun Heo */ 2312111c225aSTejun Heo static int rescuer_thread(void *__rescuer) 2313e22bee78STejun Heo { 2314111c225aSTejun Heo struct worker *rescuer = __rescuer; 2315111c225aSTejun Heo struct workqueue_struct *wq = rescuer->rescue_wq; 2316e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 2317e22bee78STejun Heo 2318e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2319111c225aSTejun Heo 2320111c225aSTejun Heo /* 2321111c225aSTejun Heo * Mark rescuer as worker too. As WORKER_PREP is never cleared, it 2322111c225aSTejun Heo * doesn't participate in concurrency management. 2323111c225aSTejun Heo */ 2324111c225aSTejun Heo rescuer->task->flags |= PF_WQ_WORKER; 2325e22bee78STejun Heo repeat: 2326e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 23271da177e4SLinus Torvalds 2328412d32e6SMike Galbraith if (kthread_should_stop()) { 2329412d32e6SMike Galbraith __set_current_state(TASK_RUNNING); 2330111c225aSTejun Heo rescuer->task->flags &= ~PF_WQ_WORKER; 2331e22bee78STejun Heo return 0; 2332412d32e6SMike Galbraith } 23331da177e4SLinus Torvalds 2334493a1724STejun Heo /* see whether any pwq is asking for help */ 2335493a1724STejun Heo spin_lock_irq(&workqueue_lock); 2336493a1724STejun Heo 2337493a1724STejun Heo while (!list_empty(&wq->maydays)) { 2338493a1724STejun Heo struct pool_workqueue *pwq = list_first_entry(&wq->maydays, 2339493a1724STejun Heo struct pool_workqueue, mayday_node); 2340112202d9STejun Heo struct worker_pool *pool = pwq->pool; 2341e22bee78STejun Heo struct work_struct *work, *n; 2342e22bee78STejun Heo 2343e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2344493a1724STejun Heo list_del_init(&pwq->mayday_node); 2345493a1724STejun Heo 2346493a1724STejun Heo spin_unlock_irq(&workqueue_lock); 2347e22bee78STejun Heo 2348e22bee78STejun Heo /* migrate to the target cpu if possible */ 2349f36dc67bSLai Jiangshan worker_maybe_bind_and_lock(pool); 2350b3104104SLai Jiangshan rescuer->pool = pool; 2351e22bee78STejun Heo 2352e22bee78STejun Heo /* 2353e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2354e22bee78STejun Heo * process'em. 2355e22bee78STejun Heo */ 23566183c009STejun Heo WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); 2357bd7bdd43STejun Heo list_for_each_entry_safe(work, n, &pool->worklist, entry) 2358112202d9STejun Heo if (get_work_pwq(work) == pwq) 2359e22bee78STejun Heo move_linked_works(work, scheduled, &n); 2360e22bee78STejun Heo 2361e22bee78STejun Heo process_scheduled_works(rescuer); 23627576958aSTejun Heo 23637576958aSTejun Heo /* 2364d565ed63STejun Heo * Leave this pool. If keep_working() is %true, notify a 23657576958aSTejun Heo * regular worker; otherwise, we end up with 0 concurrency 23667576958aSTejun Heo * and stalling the execution. 23677576958aSTejun Heo */ 236863d95a91STejun Heo if (keep_working(pool)) 236963d95a91STejun Heo wake_up_worker(pool); 23707576958aSTejun Heo 2371b3104104SLai Jiangshan rescuer->pool = NULL; 2372493a1724STejun Heo spin_unlock(&pool->lock); 2373493a1724STejun Heo spin_lock(&workqueue_lock); 23741da177e4SLinus Torvalds } 23751da177e4SLinus Torvalds 2376493a1724STejun Heo spin_unlock_irq(&workqueue_lock); 2377493a1724STejun Heo 2378111c225aSTejun Heo /* rescuers should never participate in concurrency management */ 2379111c225aSTejun Heo WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); 2380e22bee78STejun Heo schedule(); 2381e22bee78STejun Heo goto repeat; 23821da177e4SLinus Torvalds } 23831da177e4SLinus Torvalds 2384fc2e4d70SOleg Nesterov struct wq_barrier { 2385fc2e4d70SOleg Nesterov struct work_struct work; 2386fc2e4d70SOleg Nesterov struct completion done; 2387fc2e4d70SOleg Nesterov }; 2388fc2e4d70SOleg Nesterov 2389fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2390fc2e4d70SOleg Nesterov { 2391fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2392fc2e4d70SOleg Nesterov complete(&barr->done); 2393fc2e4d70SOleg Nesterov } 2394fc2e4d70SOleg Nesterov 23954690c4abSTejun Heo /** 23964690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 2397112202d9STejun Heo * @pwq: pwq to insert barrier into 23984690c4abSTejun Heo * @barr: wq_barrier to insert 2399affee4b2STejun Heo * @target: target work to attach @barr to 2400affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 24014690c4abSTejun Heo * 2402affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2403affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2404affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2405affee4b2STejun Heo * cpu. 2406affee4b2STejun Heo * 2407affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2408affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2409affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2410affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2411affee4b2STejun Heo * after a work with LINKED flag set. 2412affee4b2STejun Heo * 2413affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2414112202d9STejun Heo * underneath us, so we can't reliably determine pwq from @target. 24154690c4abSTejun Heo * 24164690c4abSTejun Heo * CONTEXT: 2417d565ed63STejun Heo * spin_lock_irq(pool->lock). 24184690c4abSTejun Heo */ 2419112202d9STejun Heo static void insert_wq_barrier(struct pool_workqueue *pwq, 2420affee4b2STejun Heo struct wq_barrier *barr, 2421affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2422fc2e4d70SOleg Nesterov { 2423affee4b2STejun Heo struct list_head *head; 2424affee4b2STejun Heo unsigned int linked = 0; 2425affee4b2STejun Heo 2426dc186ad7SThomas Gleixner /* 2427d565ed63STejun Heo * debugobject calls are safe here even with pool->lock locked 2428dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2429dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2430dc186ad7SThomas Gleixner * might deadlock. 2431dc186ad7SThomas Gleixner */ 2432ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 243322df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2434fc2e4d70SOleg Nesterov init_completion(&barr->done); 243583c22520SOleg Nesterov 2436affee4b2STejun Heo /* 2437affee4b2STejun Heo * If @target is currently being executed, schedule the 2438affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2439affee4b2STejun Heo */ 2440affee4b2STejun Heo if (worker) 2441affee4b2STejun Heo head = worker->scheduled.next; 2442affee4b2STejun Heo else { 2443affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2444affee4b2STejun Heo 2445affee4b2STejun Heo head = target->entry.next; 2446affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2447affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2448affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2449affee4b2STejun Heo } 2450affee4b2STejun Heo 2451dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2452112202d9STejun Heo insert_work(pwq, &barr->work, head, 2453affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2454fc2e4d70SOleg Nesterov } 2455fc2e4d70SOleg Nesterov 245673f53c4aSTejun Heo /** 2457112202d9STejun Heo * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing 245873f53c4aSTejun Heo * @wq: workqueue being flushed 245973f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 246073f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 246173f53c4aSTejun Heo * 2462112202d9STejun Heo * Prepare pwqs for workqueue flushing. 246373f53c4aSTejun Heo * 2464112202d9STejun Heo * If @flush_color is non-negative, flush_color on all pwqs should be 2465112202d9STejun Heo * -1. If no pwq has in-flight commands at the specified color, all 2466112202d9STejun Heo * pwq->flush_color's stay at -1 and %false is returned. If any pwq 2467112202d9STejun Heo * has in flight commands, its pwq->flush_color is set to 2468112202d9STejun Heo * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq 246973f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 247073f53c4aSTejun Heo * 247173f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 247273f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 247373f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 247473f53c4aSTejun Heo * is returned. 247573f53c4aSTejun Heo * 2476112202d9STejun Heo * If @work_color is non-negative, all pwqs should have the same 247773f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 247873f53c4aSTejun Heo * advanced to @work_color. 247973f53c4aSTejun Heo * 248073f53c4aSTejun Heo * CONTEXT: 248173f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 248273f53c4aSTejun Heo * 248373f53c4aSTejun Heo * RETURNS: 248473f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 248573f53c4aSTejun Heo * otherwise. 248673f53c4aSTejun Heo */ 2487112202d9STejun Heo static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, 248873f53c4aSTejun Heo int flush_color, int work_color) 24891da177e4SLinus Torvalds { 249073f53c4aSTejun Heo bool wait = false; 249149e3cf44STejun Heo struct pool_workqueue *pwq; 24921da177e4SLinus Torvalds 249373f53c4aSTejun Heo if (flush_color >= 0) { 24946183c009STejun Heo WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); 2495112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 1); 2496dc186ad7SThomas Gleixner } 249714441960SOleg Nesterov 249849e3cf44STejun Heo for_each_pwq(pwq, wq) { 2499112202d9STejun Heo struct worker_pool *pool = pwq->pool; 25001da177e4SLinus Torvalds 2501d565ed63STejun Heo spin_lock_irq(&pool->lock); 250273f53c4aSTejun Heo 250373f53c4aSTejun Heo if (flush_color >= 0) { 25046183c009STejun Heo WARN_ON_ONCE(pwq->flush_color != -1); 250573f53c4aSTejun Heo 2506112202d9STejun Heo if (pwq->nr_in_flight[flush_color]) { 2507112202d9STejun Heo pwq->flush_color = flush_color; 2508112202d9STejun Heo atomic_inc(&wq->nr_pwqs_to_flush); 250973f53c4aSTejun Heo wait = true; 25101da177e4SLinus Torvalds } 251173f53c4aSTejun Heo } 251273f53c4aSTejun Heo 251373f53c4aSTejun Heo if (work_color >= 0) { 25146183c009STejun Heo WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); 2515112202d9STejun Heo pwq->work_color = work_color; 251673f53c4aSTejun Heo } 251773f53c4aSTejun Heo 2518d565ed63STejun Heo spin_unlock_irq(&pool->lock); 25191da177e4SLinus Torvalds } 25201da177e4SLinus Torvalds 2521112202d9STejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) 252273f53c4aSTejun Heo complete(&wq->first_flusher->done); 252373f53c4aSTejun Heo 252473f53c4aSTejun Heo return wait; 252583c22520SOleg Nesterov } 25261da177e4SLinus Torvalds 25270fcb78c2SRolf Eike Beer /** 25281da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 25290fcb78c2SRolf Eike Beer * @wq: workqueue to flush 25301da177e4SLinus Torvalds * 25311da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 25321da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 25331da177e4SLinus Torvalds * 2534fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2535fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 25361da177e4SLinus Torvalds */ 25377ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 25381da177e4SLinus Torvalds { 253973f53c4aSTejun Heo struct wq_flusher this_flusher = { 254073f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 254173f53c4aSTejun Heo .flush_color = -1, 254273f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 254373f53c4aSTejun Heo }; 254473f53c4aSTejun Heo int next_color; 2545b1f4ec17SOleg Nesterov 25463295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 25473295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 254873f53c4aSTejun Heo 254973f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 255073f53c4aSTejun Heo 255173f53c4aSTejun Heo /* 255273f53c4aSTejun Heo * Start-to-wait phase 255373f53c4aSTejun Heo */ 255473f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 255573f53c4aSTejun Heo 255673f53c4aSTejun Heo if (next_color != wq->flush_color) { 255773f53c4aSTejun Heo /* 255873f53c4aSTejun Heo * Color space is not full. The current work_color 255973f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 256073f53c4aSTejun Heo * by one. 256173f53c4aSTejun Heo */ 25626183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); 256373f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 256473f53c4aSTejun Heo wq->work_color = next_color; 256573f53c4aSTejun Heo 256673f53c4aSTejun Heo if (!wq->first_flusher) { 256773f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 25686183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 256973f53c4aSTejun Heo 257073f53c4aSTejun Heo wq->first_flusher = &this_flusher; 257173f53c4aSTejun Heo 2572112202d9STejun Heo if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, 257373f53c4aSTejun Heo wq->work_color)) { 257473f53c4aSTejun Heo /* nothing to flush, done */ 257573f53c4aSTejun Heo wq->flush_color = next_color; 257673f53c4aSTejun Heo wq->first_flusher = NULL; 257773f53c4aSTejun Heo goto out_unlock; 257873f53c4aSTejun Heo } 257973f53c4aSTejun Heo } else { 258073f53c4aSTejun Heo /* wait in queue */ 25816183c009STejun Heo WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); 258273f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 2583112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 258473f53c4aSTejun Heo } 258573f53c4aSTejun Heo } else { 258673f53c4aSTejun Heo /* 258773f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 258873f53c4aSTejun Heo * The next flush completion will assign us 258973f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 259073f53c4aSTejun Heo */ 259173f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 259273f53c4aSTejun Heo } 259373f53c4aSTejun Heo 259473f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 259573f53c4aSTejun Heo 259673f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 259773f53c4aSTejun Heo 259873f53c4aSTejun Heo /* 259973f53c4aSTejun Heo * Wake-up-and-cascade phase 260073f53c4aSTejun Heo * 260173f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 260273f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 260373f53c4aSTejun Heo */ 260473f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 260573f53c4aSTejun Heo return; 260673f53c4aSTejun Heo 260773f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 260873f53c4aSTejun Heo 26094ce48b37STejun Heo /* we might have raced, check again with mutex held */ 26104ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 26114ce48b37STejun Heo goto out_unlock; 26124ce48b37STejun Heo 261373f53c4aSTejun Heo wq->first_flusher = NULL; 261473f53c4aSTejun Heo 26156183c009STejun Heo WARN_ON_ONCE(!list_empty(&this_flusher.list)); 26166183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 261773f53c4aSTejun Heo 261873f53c4aSTejun Heo while (true) { 261973f53c4aSTejun Heo struct wq_flusher *next, *tmp; 262073f53c4aSTejun Heo 262173f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 262273f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 262373f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 262473f53c4aSTejun Heo break; 262573f53c4aSTejun Heo list_del_init(&next->list); 262673f53c4aSTejun Heo complete(&next->done); 262773f53c4aSTejun Heo } 262873f53c4aSTejun Heo 26296183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && 263073f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 263173f53c4aSTejun Heo 263273f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 263373f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 263473f53c4aSTejun Heo 263573f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 263673f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 263773f53c4aSTejun Heo /* 263873f53c4aSTejun Heo * Assign the same color to all overflowed 263973f53c4aSTejun Heo * flushers, advance work_color and append to 264073f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 264173f53c4aSTejun Heo * phase for these overflowed flushers. 264273f53c4aSTejun Heo */ 264373f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 264473f53c4aSTejun Heo tmp->flush_color = wq->work_color; 264573f53c4aSTejun Heo 264673f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 264773f53c4aSTejun Heo 264873f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 264973f53c4aSTejun Heo &wq->flusher_queue); 2650112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 265173f53c4aSTejun Heo } 265273f53c4aSTejun Heo 265373f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 26546183c009STejun Heo WARN_ON_ONCE(wq->flush_color != wq->work_color); 265573f53c4aSTejun Heo break; 265673f53c4aSTejun Heo } 265773f53c4aSTejun Heo 265873f53c4aSTejun Heo /* 265973f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 2660112202d9STejun Heo * the new first flusher and arm pwqs. 266173f53c4aSTejun Heo */ 26626183c009STejun Heo WARN_ON_ONCE(wq->flush_color == wq->work_color); 26636183c009STejun Heo WARN_ON_ONCE(wq->flush_color != next->flush_color); 266473f53c4aSTejun Heo 266573f53c4aSTejun Heo list_del_init(&next->list); 266673f53c4aSTejun Heo wq->first_flusher = next; 266773f53c4aSTejun Heo 2668112202d9STejun Heo if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) 266973f53c4aSTejun Heo break; 267073f53c4aSTejun Heo 267173f53c4aSTejun Heo /* 267273f53c4aSTejun Heo * Meh... this color is already done, clear first 267373f53c4aSTejun Heo * flusher and repeat cascading. 267473f53c4aSTejun Heo */ 267573f53c4aSTejun Heo wq->first_flusher = NULL; 267673f53c4aSTejun Heo } 267773f53c4aSTejun Heo 267873f53c4aSTejun Heo out_unlock: 267973f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 26801da177e4SLinus Torvalds } 2681ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 26821da177e4SLinus Torvalds 26839c5a2ba7STejun Heo /** 26849c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 26859c5a2ba7STejun Heo * @wq: workqueue to drain 26869c5a2ba7STejun Heo * 26879c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 26889c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 26899c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 26909c5a2ba7STejun Heo * repeatedly until it becomes empty. The number of flushing is detemined 26919c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 26929c5a2ba7STejun Heo * takes too long. 26939c5a2ba7STejun Heo */ 26949c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 26959c5a2ba7STejun Heo { 26969c5a2ba7STejun Heo unsigned int flush_cnt = 0; 269749e3cf44STejun Heo struct pool_workqueue *pwq; 26989c5a2ba7STejun Heo 26999c5a2ba7STejun Heo /* 27009c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 27019c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 27029c5a2ba7STejun Heo * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. 27039c5a2ba7STejun Heo */ 2704e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 27059c5a2ba7STejun Heo if (!wq->nr_drainers++) 27069c5a2ba7STejun Heo wq->flags |= WQ_DRAINING; 2707e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 27089c5a2ba7STejun Heo reflush: 27099c5a2ba7STejun Heo flush_workqueue(wq); 27109c5a2ba7STejun Heo 271149e3cf44STejun Heo for_each_pwq(pwq, wq) { 2712fa2563e4SThomas Tuttle bool drained; 27139c5a2ba7STejun Heo 2714112202d9STejun Heo spin_lock_irq(&pwq->pool->lock); 2715112202d9STejun Heo drained = !pwq->nr_active && list_empty(&pwq->delayed_works); 2716112202d9STejun Heo spin_unlock_irq(&pwq->pool->lock); 2717fa2563e4SThomas Tuttle 2718fa2563e4SThomas Tuttle if (drained) 27199c5a2ba7STejun Heo continue; 27209c5a2ba7STejun Heo 27219c5a2ba7STejun Heo if (++flush_cnt == 10 || 27229c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 2723044c782cSValentin Ilie pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n", 27249c5a2ba7STejun Heo wq->name, flush_cnt); 27259c5a2ba7STejun Heo goto reflush; 27269c5a2ba7STejun Heo } 27279c5a2ba7STejun Heo 2728e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 27299c5a2ba7STejun Heo if (!--wq->nr_drainers) 27309c5a2ba7STejun Heo wq->flags &= ~WQ_DRAINING; 2731e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 27329c5a2ba7STejun Heo } 27339c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 27349c5a2ba7STejun Heo 2735606a5020STejun Heo static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) 2736baf59022STejun Heo { 2737baf59022STejun Heo struct worker *worker = NULL; 2738c9e7cf27STejun Heo struct worker_pool *pool; 2739112202d9STejun Heo struct pool_workqueue *pwq; 2740baf59022STejun Heo 2741baf59022STejun Heo might_sleep(); 2742c9e7cf27STejun Heo pool = get_work_pool(work); 2743c9e7cf27STejun Heo if (!pool) 2744baf59022STejun Heo return false; 2745baf59022STejun Heo 2746d565ed63STejun Heo spin_lock_irq(&pool->lock); 27470b3dae68SLai Jiangshan /* see the comment in try_to_grab_pending() with the same code */ 2748112202d9STejun Heo pwq = get_work_pwq(work); 2749112202d9STejun Heo if (pwq) { 2750112202d9STejun Heo if (unlikely(pwq->pool != pool)) 2751baf59022STejun Heo goto already_gone; 2752606a5020STejun Heo } else { 2753c9e7cf27STejun Heo worker = find_worker_executing_work(pool, work); 2754baf59022STejun Heo if (!worker) 2755baf59022STejun Heo goto already_gone; 2756112202d9STejun Heo pwq = worker->current_pwq; 2757606a5020STejun Heo } 2758baf59022STejun Heo 2759112202d9STejun Heo insert_wq_barrier(pwq, barr, work, worker); 2760d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2761baf59022STejun Heo 2762e159489bSTejun Heo /* 2763e159489bSTejun Heo * If @max_active is 1 or rescuer is in use, flushing another work 2764e159489bSTejun Heo * item on the same workqueue may lead to deadlock. Make sure the 2765e159489bSTejun Heo * flusher is not running on the same workqueue by verifying write 2766e159489bSTejun Heo * access. 2767e159489bSTejun Heo */ 2768112202d9STejun Heo if (pwq->wq->saved_max_active == 1 || pwq->wq->flags & WQ_RESCUER) 2769112202d9STejun Heo lock_map_acquire(&pwq->wq->lockdep_map); 2770e159489bSTejun Heo else 2771112202d9STejun Heo lock_map_acquire_read(&pwq->wq->lockdep_map); 2772112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 2773e159489bSTejun Heo 2774baf59022STejun Heo return true; 2775baf59022STejun Heo already_gone: 2776d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2777baf59022STejun Heo return false; 2778baf59022STejun Heo } 2779baf59022STejun Heo 2780db700897SOleg Nesterov /** 2781401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 2782401a8d04STejun Heo * @work: the work to flush 2783db700897SOleg Nesterov * 2784606a5020STejun Heo * Wait until @work has finished execution. @work is guaranteed to be idle 2785606a5020STejun Heo * on return if it hasn't been requeued since flush started. 2786401a8d04STejun Heo * 2787401a8d04STejun Heo * RETURNS: 2788401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2789401a8d04STejun Heo * %false if it was already idle. 2790db700897SOleg Nesterov */ 2791401a8d04STejun Heo bool flush_work(struct work_struct *work) 2792db700897SOleg Nesterov { 2793db700897SOleg Nesterov struct wq_barrier barr; 2794db700897SOleg Nesterov 27950976dfc1SStephen Boyd lock_map_acquire(&work->lockdep_map); 27960976dfc1SStephen Boyd lock_map_release(&work->lockdep_map); 27970976dfc1SStephen Boyd 2798606a5020STejun Heo if (start_flush_work(work, &barr)) { 2799db700897SOleg Nesterov wait_for_completion(&barr.done); 2800dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2801401a8d04STejun Heo return true; 2802606a5020STejun Heo } else { 2803401a8d04STejun Heo return false; 2804db700897SOleg Nesterov } 2805606a5020STejun Heo } 2806db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2807db700897SOleg Nesterov 280836e227d2STejun Heo static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 2809401a8d04STejun Heo { 2810bbb68dfaSTejun Heo unsigned long flags; 28111f1f642eSOleg Nesterov int ret; 28121f1f642eSOleg Nesterov 28131f1f642eSOleg Nesterov do { 2814bbb68dfaSTejun Heo ret = try_to_grab_pending(work, is_dwork, &flags); 2815bbb68dfaSTejun Heo /* 2816bbb68dfaSTejun Heo * If someone else is canceling, wait for the same event it 2817bbb68dfaSTejun Heo * would be waiting for before retrying. 2818bbb68dfaSTejun Heo */ 2819bbb68dfaSTejun Heo if (unlikely(ret == -ENOENT)) 2820606a5020STejun Heo flush_work(work); 28211f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 28221f1f642eSOleg Nesterov 2823bbb68dfaSTejun Heo /* tell other tasks trying to grab @work to back off */ 2824bbb68dfaSTejun Heo mark_work_canceling(work); 2825bbb68dfaSTejun Heo local_irq_restore(flags); 2826bbb68dfaSTejun Heo 2827606a5020STejun Heo flush_work(work); 28287a22ad75STejun Heo clear_work_data(work); 28291f1f642eSOleg Nesterov return ret; 28301f1f642eSOleg Nesterov } 28311f1f642eSOleg Nesterov 28326e84d644SOleg Nesterov /** 2833401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 2834401a8d04STejun Heo * @work: the work to cancel 28356e84d644SOleg Nesterov * 2836401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 2837401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 2838401a8d04STejun Heo * another workqueue. On return from this function, @work is 2839401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 28401f1f642eSOleg Nesterov * 2841401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 2842401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 28436e84d644SOleg Nesterov * 2844401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 28456e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 2846401a8d04STejun Heo * 2847401a8d04STejun Heo * RETURNS: 2848401a8d04STejun Heo * %true if @work was pending, %false otherwise. 28496e84d644SOleg Nesterov */ 2850401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 28516e84d644SOleg Nesterov { 285236e227d2STejun Heo return __cancel_work_timer(work, false); 2853b89deed3SOleg Nesterov } 285428e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2855b89deed3SOleg Nesterov 28566e84d644SOleg Nesterov /** 2857401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 2858401a8d04STejun Heo * @dwork: the delayed work to flush 28596e84d644SOleg Nesterov * 2860401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 2861401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 2862401a8d04STejun Heo * considers the last queueing instance of @dwork. 28631f1f642eSOleg Nesterov * 2864401a8d04STejun Heo * RETURNS: 2865401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2866401a8d04STejun Heo * %false if it was already idle. 28676e84d644SOleg Nesterov */ 2868401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 2869401a8d04STejun Heo { 28708930cabaSTejun Heo local_irq_disable(); 2871401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 287260c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 28738930cabaSTejun Heo local_irq_enable(); 2874401a8d04STejun Heo return flush_work(&dwork->work); 2875401a8d04STejun Heo } 2876401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 2877401a8d04STejun Heo 2878401a8d04STejun Heo /** 287957b30ae7STejun Heo * cancel_delayed_work - cancel a delayed work 288057b30ae7STejun Heo * @dwork: delayed_work to cancel 288109383498STejun Heo * 288257b30ae7STejun Heo * Kill off a pending delayed_work. Returns %true if @dwork was pending 288357b30ae7STejun Heo * and canceled; %false if wasn't pending. Note that the work callback 288457b30ae7STejun Heo * function may still be running on return, unless it returns %true and the 288557b30ae7STejun Heo * work doesn't re-arm itself. Explicitly flush or use 288657b30ae7STejun Heo * cancel_delayed_work_sync() to wait on it. 288709383498STejun Heo * 288857b30ae7STejun Heo * This function is safe to call from any context including IRQ handler. 288909383498STejun Heo */ 289057b30ae7STejun Heo bool cancel_delayed_work(struct delayed_work *dwork) 289109383498STejun Heo { 289257b30ae7STejun Heo unsigned long flags; 289357b30ae7STejun Heo int ret; 289457b30ae7STejun Heo 289557b30ae7STejun Heo do { 289657b30ae7STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 289757b30ae7STejun Heo } while (unlikely(ret == -EAGAIN)); 289857b30ae7STejun Heo 289957b30ae7STejun Heo if (unlikely(ret < 0)) 290057b30ae7STejun Heo return false; 290157b30ae7STejun Heo 29027c3eed5cSTejun Heo set_work_pool_and_clear_pending(&dwork->work, 29037c3eed5cSTejun Heo get_work_pool_id(&dwork->work)); 290457b30ae7STejun Heo local_irq_restore(flags); 2905c0158ca6SDan Magenheimer return ret; 290609383498STejun Heo } 290757b30ae7STejun Heo EXPORT_SYMBOL(cancel_delayed_work); 290809383498STejun Heo 290909383498STejun Heo /** 2910401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 2911401a8d04STejun Heo * @dwork: the delayed work cancel 2912401a8d04STejun Heo * 2913401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 2914401a8d04STejun Heo * 2915401a8d04STejun Heo * RETURNS: 2916401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 2917401a8d04STejun Heo */ 2918401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 29196e84d644SOleg Nesterov { 292036e227d2STejun Heo return __cancel_work_timer(&dwork->work, true); 29216e84d644SOleg Nesterov } 2922f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 29231da177e4SLinus Torvalds 29240fcb78c2SRolf Eike Beer /** 2925c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2926c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2927c1a220e7SZhang Rui * @work: job to be done 2928c1a220e7SZhang Rui * 2929c1a220e7SZhang Rui * This puts a job on a specific cpu 2930c1a220e7SZhang Rui */ 2931d4283e93STejun Heo bool schedule_work_on(int cpu, struct work_struct *work) 2932c1a220e7SZhang Rui { 2933d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 2934c1a220e7SZhang Rui } 2935c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 2936c1a220e7SZhang Rui 29370fcb78c2SRolf Eike Beer /** 2938ae90dd5dSDave Jones * schedule_work - put work task in global workqueue 29391da177e4SLinus Torvalds * @work: job to be done 29401da177e4SLinus Torvalds * 2941d4283e93STejun Heo * Returns %false if @work was already on the kernel-global workqueue and 2942d4283e93STejun Heo * %true otherwise. 294352bad64dSDavid Howells * 29440fcb78c2SRolf Eike Beer * This puts a job in the kernel-global workqueue if it was not already 29450fcb78c2SRolf Eike Beer * queued and leaves it in the same position on the kernel-global 29460fcb78c2SRolf Eike Beer * workqueue otherwise. 29471da177e4SLinus Torvalds */ 2948d4283e93STejun Heo bool schedule_work(struct work_struct *work) 29491da177e4SLinus Torvalds { 29500fcb78c2SRolf Eike Beer return queue_work(system_wq, work); 29511da177e4SLinus Torvalds } 29520fcb78c2SRolf Eike Beer EXPORT_SYMBOL(schedule_work); 29531da177e4SLinus Torvalds 29540fcb78c2SRolf Eike Beer /** 29550fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 29560fcb78c2SRolf Eike Beer * @cpu: cpu to use 29570fcb78c2SRolf Eike Beer * @dwork: job to be done 29580fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 29590fcb78c2SRolf Eike Beer * 29600fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 29610fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 29620fcb78c2SRolf Eike Beer */ 2963d4283e93STejun Heo bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork, 2964d4283e93STejun Heo unsigned long delay) 29651da177e4SLinus Torvalds { 2966d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 29671da177e4SLinus Torvalds } 2968ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 29691da177e4SLinus Torvalds 2970b6136773SAndrew Morton /** 29710a13c00eSTejun Heo * schedule_delayed_work - put work task in global workqueue after delay 29720a13c00eSTejun Heo * @dwork: job to be done 29730a13c00eSTejun Heo * @delay: number of jiffies to wait or 0 for immediate execution 29740a13c00eSTejun Heo * 29750a13c00eSTejun Heo * After waiting for a given time this puts a job in the kernel-global 29760a13c00eSTejun Heo * workqueue. 29770a13c00eSTejun Heo */ 2978d4283e93STejun Heo bool schedule_delayed_work(struct delayed_work *dwork, unsigned long delay) 29790a13c00eSTejun Heo { 29800a13c00eSTejun Heo return queue_delayed_work(system_wq, dwork, delay); 29810a13c00eSTejun Heo } 29820a13c00eSTejun Heo EXPORT_SYMBOL(schedule_delayed_work); 29830a13c00eSTejun Heo 29840a13c00eSTejun Heo /** 298531ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 2986b6136773SAndrew Morton * @func: the function to call 2987b6136773SAndrew Morton * 298831ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 298931ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 2990b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 299131ddd871STejun Heo * 299231ddd871STejun Heo * RETURNS: 299331ddd871STejun Heo * 0 on success, -errno on failure. 2994b6136773SAndrew Morton */ 299565f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 299615316ba8SChristoph Lameter { 299715316ba8SChristoph Lameter int cpu; 299838f51568SNamhyung Kim struct work_struct __percpu *works; 299915316ba8SChristoph Lameter 3000b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 3001b6136773SAndrew Morton if (!works) 300215316ba8SChristoph Lameter return -ENOMEM; 3003b6136773SAndrew Morton 300495402b38SGautham R Shenoy get_online_cpus(); 300593981800STejun Heo 300615316ba8SChristoph Lameter for_each_online_cpu(cpu) { 30079bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 30089bfb1839SIngo Molnar 30099bfb1839SIngo Molnar INIT_WORK(work, func); 30108de6d308SOleg Nesterov schedule_work_on(cpu, work); 301115316ba8SChristoph Lameter } 301293981800STejun Heo 301393981800STejun Heo for_each_online_cpu(cpu) 30148616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 301593981800STejun Heo 301695402b38SGautham R Shenoy put_online_cpus(); 3017b6136773SAndrew Morton free_percpu(works); 301815316ba8SChristoph Lameter return 0; 301915316ba8SChristoph Lameter } 302015316ba8SChristoph Lameter 3021eef6a7d5SAlan Stern /** 3022eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 3023eef6a7d5SAlan Stern * 3024eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 3025eef6a7d5SAlan Stern * completion. 3026eef6a7d5SAlan Stern * 3027eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 3028eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 3029eef6a7d5SAlan Stern * will lead to deadlock: 3030eef6a7d5SAlan Stern * 3031eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 3032eef6a7d5SAlan Stern * a lock held by your code or its caller. 3033eef6a7d5SAlan Stern * 3034eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 3035eef6a7d5SAlan Stern * 3036eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 3037eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 3038eef6a7d5SAlan Stern * what locks they need, which you have no control over. 3039eef6a7d5SAlan Stern * 3040eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 3041eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 3042eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 3043eef6a7d5SAlan Stern * cancel_work_sync() instead. 3044eef6a7d5SAlan Stern */ 30451da177e4SLinus Torvalds void flush_scheduled_work(void) 30461da177e4SLinus Torvalds { 3047d320c038STejun Heo flush_workqueue(system_wq); 30481da177e4SLinus Torvalds } 3049ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 30501da177e4SLinus Torvalds 30511da177e4SLinus Torvalds /** 30521fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 30531fa44ecaSJames Bottomley * @fn: the function to execute 30541fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 30551fa44ecaSJames Bottomley * be available when the work executes) 30561fa44ecaSJames Bottomley * 30571fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 30581fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 30591fa44ecaSJames Bottomley * 30601fa44ecaSJames Bottomley * Returns: 0 - function was executed 30611fa44ecaSJames Bottomley * 1 - function was scheduled for execution 30621fa44ecaSJames Bottomley */ 306365f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 30641fa44ecaSJames Bottomley { 30651fa44ecaSJames Bottomley if (!in_interrupt()) { 306665f27f38SDavid Howells fn(&ew->work); 30671fa44ecaSJames Bottomley return 0; 30681fa44ecaSJames Bottomley } 30691fa44ecaSJames Bottomley 307065f27f38SDavid Howells INIT_WORK(&ew->work, fn); 30711fa44ecaSJames Bottomley schedule_work(&ew->work); 30721fa44ecaSJames Bottomley 30731fa44ecaSJames Bottomley return 1; 30741fa44ecaSJames Bottomley } 30751fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 30761fa44ecaSJames Bottomley 30771da177e4SLinus Torvalds int keventd_up(void) 30781da177e4SLinus Torvalds { 3079d320c038STejun Heo return system_wq != NULL; 30801da177e4SLinus Torvalds } 30811da177e4SLinus Torvalds 308230cdf249STejun Heo static int alloc_and_link_pwqs(struct workqueue_struct *wq) 30831da177e4SLinus Torvalds { 308449e3cf44STejun Heo bool highpri = wq->flags & WQ_HIGHPRI; 308530cdf249STejun Heo int cpu; 3086e1d8aa9fSFrederic Weisbecker 308730cdf249STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 308830cdf249STejun Heo wq->pool_wq.pcpu = alloc_percpu(struct pool_workqueue); 308930cdf249STejun Heo if (!wq->pool_wq.pcpu) 309030cdf249STejun Heo return -ENOMEM; 309130cdf249STejun Heo 309230cdf249STejun Heo for_each_possible_cpu(cpu) { 309330cdf249STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 309430cdf249STejun Heo 309549e3cf44STejun Heo pwq->pool = get_std_worker_pool(cpu, highpri); 309630cdf249STejun Heo list_add_tail(&pwq->pwqs_node, &wq->pwqs); 309730cdf249STejun Heo } 309830cdf249STejun Heo } else { 309930cdf249STejun Heo struct pool_workqueue *pwq; 310030cdf249STejun Heo 310130cdf249STejun Heo pwq = kmem_cache_zalloc(pwq_cache, GFP_KERNEL); 310230cdf249STejun Heo if (!pwq) 310330cdf249STejun Heo return -ENOMEM; 310430cdf249STejun Heo 310530cdf249STejun Heo wq->pool_wq.single = pwq; 310649e3cf44STejun Heo pwq->pool = get_std_worker_pool(WORK_CPU_UNBOUND, highpri); 310730cdf249STejun Heo list_add_tail(&pwq->pwqs_node, &wq->pwqs); 310830cdf249STejun Heo } 310930cdf249STejun Heo 311030cdf249STejun Heo return 0; 31110f900049STejun Heo } 31120f900049STejun Heo 3113112202d9STejun Heo static void free_pwqs(struct workqueue_struct *wq) 311406ba38a9SOleg Nesterov { 3115e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 3116112202d9STejun Heo free_percpu(wq->pool_wq.pcpu); 3117e904e6c2STejun Heo else 3118e904e6c2STejun Heo kmem_cache_free(pwq_cache, wq->pool_wq.single); 311906ba38a9SOleg Nesterov } 312006ba38a9SOleg Nesterov 3121f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 3122f3421797STejun Heo const char *name) 3123b71ab8c2STejun Heo { 3124f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 3125f3421797STejun Heo 3126f3421797STejun Heo if (max_active < 1 || max_active > lim) 3127044c782cSValentin Ilie pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 3128f3421797STejun Heo max_active, name, 1, lim); 3129b71ab8c2STejun Heo 3130f3421797STejun Heo return clamp_val(max_active, 1, lim); 3131b71ab8c2STejun Heo } 3132b71ab8c2STejun Heo 3133b196be89STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *fmt, 313497e37d7bSTejun Heo unsigned int flags, 31351e19ffc6STejun Heo int max_active, 3136eb13ba87SJohannes Berg struct lock_class_key *key, 3137b196be89STejun Heo const char *lock_name, ...) 31383af24433SOleg Nesterov { 3139b196be89STejun Heo va_list args, args1; 31403af24433SOleg Nesterov struct workqueue_struct *wq; 314149e3cf44STejun Heo struct pool_workqueue *pwq; 3142b196be89STejun Heo size_t namelen; 3143b196be89STejun Heo 3144b196be89STejun Heo /* determine namelen, allocate wq and format name */ 3145b196be89STejun Heo va_start(args, lock_name); 3146b196be89STejun Heo va_copy(args1, args); 3147b196be89STejun Heo namelen = vsnprintf(NULL, 0, fmt, args) + 1; 3148b196be89STejun Heo 3149b196be89STejun Heo wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL); 3150b196be89STejun Heo if (!wq) 3151b196be89STejun Heo goto err; 3152b196be89STejun Heo 3153b196be89STejun Heo vsnprintf(wq->name, namelen, fmt, args1); 3154b196be89STejun Heo va_end(args); 3155b196be89STejun Heo va_end(args1); 31563af24433SOleg Nesterov 3157f3421797STejun Heo /* 31586370a6adSTejun Heo * Workqueues which may be used during memory reclaim should 31596370a6adSTejun Heo * have a rescuer to guarantee forward progress. 31606370a6adSTejun Heo */ 31616370a6adSTejun Heo if (flags & WQ_MEM_RECLAIM) 31626370a6adSTejun Heo flags |= WQ_RESCUER; 31636370a6adSTejun Heo 3164d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 3165b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 31663af24433SOleg Nesterov 3167b196be89STejun Heo /* init wq */ 316897e37d7bSTejun Heo wq->flags = flags; 3169a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 317073f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 3171112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 0); 317230cdf249STejun Heo INIT_LIST_HEAD(&wq->pwqs); 317373f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 317473f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 3175493a1724STejun Heo INIT_LIST_HEAD(&wq->maydays); 31763af24433SOleg Nesterov 3177eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 3178cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 31793af24433SOleg Nesterov 318030cdf249STejun Heo if (alloc_and_link_pwqs(wq) < 0) 3181bdbc5dd7STejun Heo goto err; 3182bdbc5dd7STejun Heo 318349e3cf44STejun Heo for_each_pwq(pwq, wq) { 3184112202d9STejun Heo BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); 3185112202d9STejun Heo pwq->wq = wq; 3186112202d9STejun Heo pwq->flush_color = -1; 3187112202d9STejun Heo pwq->max_active = max_active; 3188112202d9STejun Heo INIT_LIST_HEAD(&pwq->delayed_works); 3189493a1724STejun Heo INIT_LIST_HEAD(&pwq->mayday_node); 3190e22bee78STejun Heo } 31911537663fSTejun Heo 3192e22bee78STejun Heo if (flags & WQ_RESCUER) { 3193e22bee78STejun Heo struct worker *rescuer; 3194e22bee78STejun Heo 3195e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 3196e22bee78STejun Heo if (!rescuer) 3197e22bee78STejun Heo goto err; 3198e22bee78STejun Heo 3199111c225aSTejun Heo rescuer->rescue_wq = wq; 3200111c225aSTejun Heo rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", 3201b196be89STejun Heo wq->name); 3202e22bee78STejun Heo if (IS_ERR(rescuer->task)) 3203e22bee78STejun Heo goto err; 3204e22bee78STejun Heo 3205e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 3206e22bee78STejun Heo wake_up_process(rescuer->task); 32073af24433SOleg Nesterov } 32081537663fSTejun Heo 32093af24433SOleg Nesterov /* 3210a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 3211a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 3212a0a1a5fdSTejun Heo * workqueue to workqueues list. 32133af24433SOleg Nesterov */ 3214e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3215a0a1a5fdSTejun Heo 321658a69cb4STejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZABLE) 321749e3cf44STejun Heo for_each_pwq(pwq, wq) 321849e3cf44STejun Heo pwq->max_active = 0; 3219a0a1a5fdSTejun Heo 32203af24433SOleg Nesterov list_add(&wq->list, &workqueues); 3221a0a1a5fdSTejun Heo 3222e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 32233af24433SOleg Nesterov 32243af24433SOleg Nesterov return wq; 32254690c4abSTejun Heo err: 32264690c4abSTejun Heo if (wq) { 3227112202d9STejun Heo free_pwqs(wq); 3228e22bee78STejun Heo kfree(wq->rescuer); 32294690c4abSTejun Heo kfree(wq); 32303af24433SOleg Nesterov } 32314690c4abSTejun Heo return NULL; 32321da177e4SLinus Torvalds } 3233d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 32341da177e4SLinus Torvalds 32353af24433SOleg Nesterov /** 32363af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 32373af24433SOleg Nesterov * @wq: target workqueue 32383af24433SOleg Nesterov * 32393af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 32403af24433SOleg Nesterov */ 32413af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 32423af24433SOleg Nesterov { 324349e3cf44STejun Heo struct pool_workqueue *pwq; 32443af24433SOleg Nesterov 32459c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 32469c5a2ba7STejun Heo drain_workqueue(wq); 3247c8efcc25STejun Heo 32486183c009STejun Heo /* sanity checks */ 324949e3cf44STejun Heo for_each_pwq(pwq, wq) { 32506183c009STejun Heo int i; 32516183c009STejun Heo 32526183c009STejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 32536183c009STejun Heo if (WARN_ON(pwq->nr_in_flight[i])) 32546183c009STejun Heo return; 32556183c009STejun Heo if (WARN_ON(pwq->nr_active) || 32566183c009STejun Heo WARN_ON(!list_empty(&pwq->delayed_works))) 32576183c009STejun Heo return; 32586183c009STejun Heo } 32596183c009STejun Heo 3260a0a1a5fdSTejun Heo /* 3261a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 3262a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 3263a0a1a5fdSTejun Heo */ 3264e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 32653af24433SOleg Nesterov list_del(&wq->list); 3266e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 32673af24433SOleg Nesterov 3268e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 3269e22bee78STejun Heo kthread_stop(wq->rescuer->task); 32708d9df9f0SXiaotian Feng kfree(wq->rescuer); 3271e22bee78STejun Heo } 3272e22bee78STejun Heo 3273112202d9STejun Heo free_pwqs(wq); 32743af24433SOleg Nesterov kfree(wq); 32753af24433SOleg Nesterov } 32763af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 32773af24433SOleg Nesterov 3278dcd989cbSTejun Heo /** 3279112202d9STejun Heo * pwq_set_max_active - adjust max_active of a pwq 3280112202d9STejun Heo * @pwq: target pool_workqueue 32819f4bd4cdSLai Jiangshan * @max_active: new max_active value. 32829f4bd4cdSLai Jiangshan * 3283112202d9STejun Heo * Set @pwq->max_active to @max_active and activate delayed works if 32849f4bd4cdSLai Jiangshan * increased. 32859f4bd4cdSLai Jiangshan * 32869f4bd4cdSLai Jiangshan * CONTEXT: 3287d565ed63STejun Heo * spin_lock_irq(pool->lock). 32889f4bd4cdSLai Jiangshan */ 3289112202d9STejun Heo static void pwq_set_max_active(struct pool_workqueue *pwq, int max_active) 32909f4bd4cdSLai Jiangshan { 3291112202d9STejun Heo pwq->max_active = max_active; 32929f4bd4cdSLai Jiangshan 3293112202d9STejun Heo while (!list_empty(&pwq->delayed_works) && 3294112202d9STejun Heo pwq->nr_active < pwq->max_active) 3295112202d9STejun Heo pwq_activate_first_delayed(pwq); 32969f4bd4cdSLai Jiangshan } 32979f4bd4cdSLai Jiangshan 32989f4bd4cdSLai Jiangshan /** 3299dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 3300dcd989cbSTejun Heo * @wq: target workqueue 3301dcd989cbSTejun Heo * @max_active: new max_active value. 3302dcd989cbSTejun Heo * 3303dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 3304dcd989cbSTejun Heo * 3305dcd989cbSTejun Heo * CONTEXT: 3306dcd989cbSTejun Heo * Don't call from IRQ context. 3307dcd989cbSTejun Heo */ 3308dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 3309dcd989cbSTejun Heo { 331049e3cf44STejun Heo struct pool_workqueue *pwq; 3311dcd989cbSTejun Heo 3312f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 3313dcd989cbSTejun Heo 3314e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3315dcd989cbSTejun Heo 3316dcd989cbSTejun Heo wq->saved_max_active = max_active; 3317dcd989cbSTejun Heo 331849e3cf44STejun Heo for_each_pwq(pwq, wq) { 3319112202d9STejun Heo struct worker_pool *pool = pwq->pool; 3320dcd989cbSTejun Heo 3321e98d5b16STejun Heo spin_lock(&pool->lock); 3322dcd989cbSTejun Heo 332358a69cb4STejun Heo if (!(wq->flags & WQ_FREEZABLE) || 332435b6bb63STejun Heo !(pool->flags & POOL_FREEZING)) 3325112202d9STejun Heo pwq_set_max_active(pwq, max_active); 3326dcd989cbSTejun Heo 3327e98d5b16STejun Heo spin_unlock(&pool->lock); 3328dcd989cbSTejun Heo } 3329dcd989cbSTejun Heo 3330e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 3331dcd989cbSTejun Heo } 3332dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 3333dcd989cbSTejun Heo 3334dcd989cbSTejun Heo /** 3335dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 3336dcd989cbSTejun Heo * @cpu: CPU in question 3337dcd989cbSTejun Heo * @wq: target workqueue 3338dcd989cbSTejun Heo * 3339dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 3340dcd989cbSTejun Heo * no synchronization around this function and the test result is 3341dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3342dcd989cbSTejun Heo * 3343dcd989cbSTejun Heo * RETURNS: 3344dcd989cbSTejun Heo * %true if congested, %false otherwise. 3345dcd989cbSTejun Heo */ 3346d84ff051STejun Heo bool workqueue_congested(int cpu, struct workqueue_struct *wq) 3347dcd989cbSTejun Heo { 3348112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 3349dcd989cbSTejun Heo 3350112202d9STejun Heo return !list_empty(&pwq->delayed_works); 3351dcd989cbSTejun Heo } 3352dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 3353dcd989cbSTejun Heo 3354dcd989cbSTejun Heo /** 3355dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 3356dcd989cbSTejun Heo * @work: the work to be tested 3357dcd989cbSTejun Heo * 3358dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 3359dcd989cbSTejun Heo * synchronization around this function and the test result is 3360dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3361dcd989cbSTejun Heo * 3362dcd989cbSTejun Heo * RETURNS: 3363dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 3364dcd989cbSTejun Heo */ 3365dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 3366dcd989cbSTejun Heo { 3367c9e7cf27STejun Heo struct worker_pool *pool = get_work_pool(work); 3368dcd989cbSTejun Heo unsigned long flags; 3369dcd989cbSTejun Heo unsigned int ret = 0; 3370dcd989cbSTejun Heo 3371dcd989cbSTejun Heo if (work_pending(work)) 3372dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 3373038366c5SLai Jiangshan 3374038366c5SLai Jiangshan if (pool) { 3375038366c5SLai Jiangshan spin_lock_irqsave(&pool->lock, flags); 3376c9e7cf27STejun Heo if (find_worker_executing_work(pool, work)) 3377dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 3378d565ed63STejun Heo spin_unlock_irqrestore(&pool->lock, flags); 3379038366c5SLai Jiangshan } 3380dcd989cbSTejun Heo 3381dcd989cbSTejun Heo return ret; 3382dcd989cbSTejun Heo } 3383dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 3384dcd989cbSTejun Heo 3385db7bccf4STejun Heo /* 3386db7bccf4STejun Heo * CPU hotplug. 3387db7bccf4STejun Heo * 3388e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 3389112202d9STejun Heo * are a lot of assumptions on strong associations among work, pwq and 3390706026c2STejun Heo * pool which make migrating pending and scheduled works very 3391e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 339294cf58bbSTejun Heo * worker pools serve mix of short, long and very long running works making 3393e22bee78STejun Heo * blocked draining impractical. 3394e22bee78STejun Heo * 339524647570STejun Heo * This is solved by allowing the pools to be disassociated from the CPU 3396628c78e7STejun Heo * running as an unbound one and allowing it to be reattached later if the 3397628c78e7STejun Heo * cpu comes back online. 3398db7bccf4STejun Heo */ 3399db7bccf4STejun Heo 3400706026c2STejun Heo static void wq_unbind_fn(struct work_struct *work) 3401db7bccf4STejun Heo { 340238db41d9STejun Heo int cpu = smp_processor_id(); 34034ce62e9eSTejun Heo struct worker_pool *pool; 3404db7bccf4STejun Heo struct worker *worker; 3405db7bccf4STejun Heo int i; 3406db7bccf4STejun Heo 340738db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 34086183c009STejun Heo WARN_ON_ONCE(cpu != smp_processor_id()); 3409db7bccf4STejun Heo 341094cf58bbSTejun Heo mutex_lock(&pool->assoc_mutex); 341194cf58bbSTejun Heo spin_lock_irq(&pool->lock); 3412e22bee78STejun Heo 3413f2d5a0eeSTejun Heo /* 341494cf58bbSTejun Heo * We've claimed all manager positions. Make all workers 341594cf58bbSTejun Heo * unbound and set DISASSOCIATED. Before this, all workers 341694cf58bbSTejun Heo * except for the ones which are still executing works from 341794cf58bbSTejun Heo * before the last CPU down must be on the cpu. After 341894cf58bbSTejun Heo * this, they may become diasporas. 3419f2d5a0eeSTejun Heo */ 34204ce62e9eSTejun Heo list_for_each_entry(worker, &pool->idle_list, entry) 3421403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 3422db7bccf4STejun Heo 3423b67bfe0dSSasha Levin for_each_busy_worker(worker, i, pool) 3424403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 3425db7bccf4STejun Heo 342624647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 3427f2d5a0eeSTejun Heo 342894cf58bbSTejun Heo spin_unlock_irq(&pool->lock); 342994cf58bbSTejun Heo mutex_unlock(&pool->assoc_mutex); 343094cf58bbSTejun Heo } 3431e22bee78STejun Heo 3432e22bee78STejun Heo /* 3433628c78e7STejun Heo * Call schedule() so that we cross rq->lock and thus can guarantee 3434628c78e7STejun Heo * sched callbacks see the %WORKER_UNBOUND flag. This is necessary 3435628c78e7STejun Heo * as scheduler callbacks may be invoked from other cpus. 3436628c78e7STejun Heo */ 3437628c78e7STejun Heo schedule(); 3438628c78e7STejun Heo 3439628c78e7STejun Heo /* 3440628c78e7STejun Heo * Sched callbacks are disabled now. Zap nr_running. After this, 3441628c78e7STejun Heo * nr_running stays zero and need_more_worker() and keep_working() 344238db41d9STejun Heo * are always true as long as the worklist is not empty. Pools on 344338db41d9STejun Heo * @cpu now behave as unbound (in terms of concurrency management) 344438db41d9STejun Heo * pools which are served by workers tied to the CPU. 3445628c78e7STejun Heo * 3446628c78e7STejun Heo * On return from this function, the current worker would trigger 3447628c78e7STejun Heo * unbound chain execution of pending work items if other workers 3448628c78e7STejun Heo * didn't already. 3449e22bee78STejun Heo */ 345038db41d9STejun Heo for_each_std_worker_pool(pool, cpu) 3451e19e397aSTejun Heo atomic_set(&pool->nr_running, 0); 3452db7bccf4STejun Heo } 3453db7bccf4STejun Heo 34548db25e78STejun Heo /* 34558db25e78STejun Heo * Workqueues should be brought up before normal priority CPU notifiers. 34568db25e78STejun Heo * This will be registered high priority CPU notifier. 34578db25e78STejun Heo */ 34589fdf9b73SLai Jiangshan static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb, 34591da177e4SLinus Torvalds unsigned long action, 34601da177e4SLinus Torvalds void *hcpu) 34611da177e4SLinus Torvalds { 3462d84ff051STejun Heo int cpu = (unsigned long)hcpu; 34634ce62e9eSTejun Heo struct worker_pool *pool; 34641da177e4SLinus Torvalds 34658db25e78STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 34663af24433SOleg Nesterov case CPU_UP_PREPARE: 346738db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 34683ce63377STejun Heo struct worker *worker; 34693ce63377STejun Heo 34703ce63377STejun Heo if (pool->nr_workers) 34713ce63377STejun Heo continue; 34723ce63377STejun Heo 34733ce63377STejun Heo worker = create_worker(pool); 34743ce63377STejun Heo if (!worker) 34753ce63377STejun Heo return NOTIFY_BAD; 34763ce63377STejun Heo 3477d565ed63STejun Heo spin_lock_irq(&pool->lock); 34783ce63377STejun Heo start_worker(worker); 3479d565ed63STejun Heo spin_unlock_irq(&pool->lock); 34803af24433SOleg Nesterov } 34811da177e4SLinus Torvalds break; 34821da177e4SLinus Torvalds 348365758202STejun Heo case CPU_DOWN_FAILED: 348465758202STejun Heo case CPU_ONLINE: 348538db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 348694cf58bbSTejun Heo mutex_lock(&pool->assoc_mutex); 348794cf58bbSTejun Heo spin_lock_irq(&pool->lock); 348894cf58bbSTejun Heo 348924647570STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 349094cf58bbSTejun Heo rebind_workers(pool); 349194cf58bbSTejun Heo 349294cf58bbSTejun Heo spin_unlock_irq(&pool->lock); 349394cf58bbSTejun Heo mutex_unlock(&pool->assoc_mutex); 349494cf58bbSTejun Heo } 34958db25e78STejun Heo break; 349665758202STejun Heo } 349765758202STejun Heo return NOTIFY_OK; 349865758202STejun Heo } 349965758202STejun Heo 350065758202STejun Heo /* 350165758202STejun Heo * Workqueues should be brought down after normal priority CPU notifiers. 350265758202STejun Heo * This will be registered as low priority CPU notifier. 350365758202STejun Heo */ 35049fdf9b73SLai Jiangshan static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb, 350565758202STejun Heo unsigned long action, 350665758202STejun Heo void *hcpu) 350765758202STejun Heo { 3508d84ff051STejun Heo int cpu = (unsigned long)hcpu; 35098db25e78STejun Heo struct work_struct unbind_work; 35108db25e78STejun Heo 351165758202STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 351265758202STejun Heo case CPU_DOWN_PREPARE: 35138db25e78STejun Heo /* unbinding should happen on the local CPU */ 3514706026c2STejun Heo INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn); 35157635d2fdSJoonsoo Kim queue_work_on(cpu, system_highpri_wq, &unbind_work); 35168db25e78STejun Heo flush_work(&unbind_work); 35178db25e78STejun Heo break; 351865758202STejun Heo } 351965758202STejun Heo return NOTIFY_OK; 352065758202STejun Heo } 352165758202STejun Heo 35222d3854a3SRusty Russell #ifdef CONFIG_SMP 35238ccad40dSRusty Russell 35242d3854a3SRusty Russell struct work_for_cpu { 3525ed48ece2STejun Heo struct work_struct work; 35262d3854a3SRusty Russell long (*fn)(void *); 35272d3854a3SRusty Russell void *arg; 35282d3854a3SRusty Russell long ret; 35292d3854a3SRusty Russell }; 35302d3854a3SRusty Russell 3531ed48ece2STejun Heo static void work_for_cpu_fn(struct work_struct *work) 35322d3854a3SRusty Russell { 3533ed48ece2STejun Heo struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); 3534ed48ece2STejun Heo 35352d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 35362d3854a3SRusty Russell } 35372d3854a3SRusty Russell 35382d3854a3SRusty Russell /** 35392d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 35402d3854a3SRusty Russell * @cpu: the cpu to run on 35412d3854a3SRusty Russell * @fn: the function to run 35422d3854a3SRusty Russell * @arg: the function arg 35432d3854a3SRusty Russell * 354431ad9081SRusty Russell * This will return the value @fn returns. 354531ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 35466b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 35472d3854a3SRusty Russell */ 3548d84ff051STejun Heo long work_on_cpu(int cpu, long (*fn)(void *), void *arg) 35492d3854a3SRusty Russell { 3550ed48ece2STejun Heo struct work_for_cpu wfc = { .fn = fn, .arg = arg }; 35512d3854a3SRusty Russell 3552ed48ece2STejun Heo INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); 3553ed48ece2STejun Heo schedule_work_on(cpu, &wfc.work); 3554ed48ece2STejun Heo flush_work(&wfc.work); 35552d3854a3SRusty Russell return wfc.ret; 35562d3854a3SRusty Russell } 35572d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 35582d3854a3SRusty Russell #endif /* CONFIG_SMP */ 35592d3854a3SRusty Russell 3560a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3561e7577c50SRusty Russell 3562a0a1a5fdSTejun Heo /** 3563a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3564a0a1a5fdSTejun Heo * 356558a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 356658a69cb4STejun Heo * workqueues will queue new works to their frozen_works list instead of 3567706026c2STejun Heo * pool->worklist. 3568a0a1a5fdSTejun Heo * 3569a0a1a5fdSTejun Heo * CONTEXT: 3570d565ed63STejun Heo * Grabs and releases workqueue_lock and pool->lock's. 3571a0a1a5fdSTejun Heo */ 3572a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3573a0a1a5fdSTejun Heo { 357417116969STejun Heo struct worker_pool *pool; 357524b8a847STejun Heo struct workqueue_struct *wq; 357624b8a847STejun Heo struct pool_workqueue *pwq; 357717116969STejun Heo int id; 3578a0a1a5fdSTejun Heo 3579e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3580a0a1a5fdSTejun Heo 35816183c009STejun Heo WARN_ON_ONCE(workqueue_freezing); 3582a0a1a5fdSTejun Heo workqueue_freezing = true; 3583a0a1a5fdSTejun Heo 358424b8a847STejun Heo /* set FREEZING */ 358517116969STejun Heo for_each_pool(pool, id) { 3586e98d5b16STejun Heo spin_lock(&pool->lock); 358735b6bb63STejun Heo WARN_ON_ONCE(pool->flags & POOL_FREEZING); 358835b6bb63STejun Heo pool->flags |= POOL_FREEZING; 358924b8a847STejun Heo spin_unlock(&pool->lock); 35901da177e4SLinus Torvalds } 35918b03ae3cSTejun Heo 359224b8a847STejun Heo /* suppress further executions by setting max_active to zero */ 359324b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 359424b8a847STejun Heo if (!(wq->flags & WQ_FREEZABLE)) 359524b8a847STejun Heo continue; 359624b8a847STejun Heo 359724b8a847STejun Heo for_each_pwq(pwq, wq) { 359824b8a847STejun Heo spin_lock(&pwq->pool->lock); 359924b8a847STejun Heo pwq->max_active = 0; 360024b8a847STejun Heo spin_unlock(&pwq->pool->lock); 360124b8a847STejun Heo } 3602a1056305STejun Heo } 3603a0a1a5fdSTejun Heo 3604e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 3605a0a1a5fdSTejun Heo } 3606a0a1a5fdSTejun Heo 3607a0a1a5fdSTejun Heo /** 360858a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 3609a0a1a5fdSTejun Heo * 3610a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3611a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3612a0a1a5fdSTejun Heo * 3613a0a1a5fdSTejun Heo * CONTEXT: 3614a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3615a0a1a5fdSTejun Heo * 3616a0a1a5fdSTejun Heo * RETURNS: 361758a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 361858a69cb4STejun Heo * is complete. 3619a0a1a5fdSTejun Heo */ 3620a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3621a0a1a5fdSTejun Heo { 3622a0a1a5fdSTejun Heo bool busy = false; 362324b8a847STejun Heo struct workqueue_struct *wq; 362424b8a847STejun Heo struct pool_workqueue *pwq; 3625a0a1a5fdSTejun Heo 3626e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3627a0a1a5fdSTejun Heo 36286183c009STejun Heo WARN_ON_ONCE(!workqueue_freezing); 3629a0a1a5fdSTejun Heo 363024b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 363124b8a847STejun Heo if (!(wq->flags & WQ_FREEZABLE)) 363224b8a847STejun Heo continue; 3633a0a1a5fdSTejun Heo /* 3634a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3635a0a1a5fdSTejun Heo * to peek without lock. 3636a0a1a5fdSTejun Heo */ 363724b8a847STejun Heo for_each_pwq(pwq, wq) { 36386183c009STejun Heo WARN_ON_ONCE(pwq->nr_active < 0); 3639112202d9STejun Heo if (pwq->nr_active) { 3640a0a1a5fdSTejun Heo busy = true; 3641a0a1a5fdSTejun Heo goto out_unlock; 3642a0a1a5fdSTejun Heo } 3643a0a1a5fdSTejun Heo } 3644a0a1a5fdSTejun Heo } 3645a0a1a5fdSTejun Heo out_unlock: 3646e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 3647a0a1a5fdSTejun Heo return busy; 3648a0a1a5fdSTejun Heo } 3649a0a1a5fdSTejun Heo 3650a0a1a5fdSTejun Heo /** 3651a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3652a0a1a5fdSTejun Heo * 3653a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 3654706026c2STejun Heo * frozen works are transferred to their respective pool worklists. 3655a0a1a5fdSTejun Heo * 3656a0a1a5fdSTejun Heo * CONTEXT: 3657d565ed63STejun Heo * Grabs and releases workqueue_lock and pool->lock's. 3658a0a1a5fdSTejun Heo */ 3659a0a1a5fdSTejun Heo void thaw_workqueues(void) 3660a0a1a5fdSTejun Heo { 366124b8a847STejun Heo struct workqueue_struct *wq; 366224b8a847STejun Heo struct pool_workqueue *pwq; 366324b8a847STejun Heo struct worker_pool *pool; 366424b8a847STejun Heo int id; 3665a0a1a5fdSTejun Heo 3666e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3667a0a1a5fdSTejun Heo 3668a0a1a5fdSTejun Heo if (!workqueue_freezing) 3669a0a1a5fdSTejun Heo goto out_unlock; 3670a0a1a5fdSTejun Heo 367124b8a847STejun Heo /* clear FREEZING */ 367224b8a847STejun Heo for_each_pool(pool, id) { 3673e98d5b16STejun Heo spin_lock(&pool->lock); 367435b6bb63STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); 367535b6bb63STejun Heo pool->flags &= ~POOL_FREEZING; 3676e98d5b16STejun Heo spin_unlock(&pool->lock); 3677d565ed63STejun Heo } 367824b8a847STejun Heo 367924b8a847STejun Heo /* restore max_active and repopulate worklist */ 368024b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 368124b8a847STejun Heo if (!(wq->flags & WQ_FREEZABLE)) 368224b8a847STejun Heo continue; 368324b8a847STejun Heo 368424b8a847STejun Heo for_each_pwq(pwq, wq) { 368524b8a847STejun Heo spin_lock(&pwq->pool->lock); 368624b8a847STejun Heo pwq_set_max_active(pwq, wq->saved_max_active); 368724b8a847STejun Heo spin_unlock(&pwq->pool->lock); 368824b8a847STejun Heo } 368924b8a847STejun Heo } 369024b8a847STejun Heo 369124b8a847STejun Heo /* kick workers */ 369224b8a847STejun Heo for_each_pool(pool, id) { 369324b8a847STejun Heo spin_lock(&pool->lock); 369424b8a847STejun Heo wake_up_worker(pool); 369524b8a847STejun Heo spin_unlock(&pool->lock); 3696a0a1a5fdSTejun Heo } 3697a0a1a5fdSTejun Heo 3698a0a1a5fdSTejun Heo workqueue_freezing = false; 3699a0a1a5fdSTejun Heo out_unlock: 3700e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 3701a0a1a5fdSTejun Heo } 3702a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3703a0a1a5fdSTejun Heo 37046ee0578bSSuresh Siddha static int __init init_workqueues(void) 37051da177e4SLinus Torvalds { 3706d84ff051STejun Heo int cpu; 3707c34056a3STejun Heo 37087c3eed5cSTejun Heo /* make sure we have enough bits for OFFQ pool ID */ 37097c3eed5cSTejun Heo BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) < 37106be19588SLai Jiangshan WORK_CPU_END * NR_STD_WORKER_POOLS); 3711b5490077STejun Heo 3712e904e6c2STejun Heo WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); 3713e904e6c2STejun Heo 3714e904e6c2STejun Heo pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); 3715e904e6c2STejun Heo 371665758202STejun Heo cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); 3717a5b4e57dSLai Jiangshan hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); 37188b03ae3cSTejun Heo 3719706026c2STejun Heo /* initialize CPU pools */ 3720706026c2STejun Heo for_each_wq_cpu(cpu) { 37214ce62e9eSTejun Heo struct worker_pool *pool; 37228b03ae3cSTejun Heo 372338db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 3724d565ed63STejun Heo spin_lock_init(&pool->lock); 3725ec22ca5eSTejun Heo pool->cpu = cpu; 372624647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 37274ce62e9eSTejun Heo INIT_LIST_HEAD(&pool->worklist); 37284ce62e9eSTejun Heo INIT_LIST_HEAD(&pool->idle_list); 3729c9e7cf27STejun Heo hash_init(pool->busy_hash); 3730e22bee78STejun Heo 37314ce62e9eSTejun Heo init_timer_deferrable(&pool->idle_timer); 37324ce62e9eSTejun Heo pool->idle_timer.function = idle_worker_timeout; 37334ce62e9eSTejun Heo pool->idle_timer.data = (unsigned long)pool; 3734e22bee78STejun Heo 3735706026c2STejun Heo setup_timer(&pool->mayday_timer, pool_mayday_timeout, 37364ce62e9eSTejun Heo (unsigned long)pool); 37374ce62e9eSTejun Heo 3738b2eb83d1SLai Jiangshan mutex_init(&pool->assoc_mutex); 37394ce62e9eSTejun Heo ida_init(&pool->worker_ida); 37409daf9e67STejun Heo 37419daf9e67STejun Heo /* alloc pool ID */ 37429daf9e67STejun Heo BUG_ON(worker_pool_assign_id(pool)); 37434ce62e9eSTejun Heo } 37448b03ae3cSTejun Heo } 37458b03ae3cSTejun Heo 3746e22bee78STejun Heo /* create the initial worker */ 3747706026c2STejun Heo for_each_online_wq_cpu(cpu) { 37484ce62e9eSTejun Heo struct worker_pool *pool; 3749e22bee78STejun Heo 375038db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 37514ce62e9eSTejun Heo struct worker *worker; 37524ce62e9eSTejun Heo 375324647570STejun Heo if (cpu != WORK_CPU_UNBOUND) 375424647570STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 375524647570STejun Heo 3756bc2ae0f5STejun Heo worker = create_worker(pool); 3757e22bee78STejun Heo BUG_ON(!worker); 3758d565ed63STejun Heo spin_lock_irq(&pool->lock); 3759e22bee78STejun Heo start_worker(worker); 3760d565ed63STejun Heo spin_unlock_irq(&pool->lock); 3761e22bee78STejun Heo } 37624ce62e9eSTejun Heo } 3763e22bee78STejun Heo 3764d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 37651aabe902SJoonsoo Kim system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 3766d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3767f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3768f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 376924d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 377024d51addSTejun Heo WQ_FREEZABLE, 0); 37711aabe902SJoonsoo Kim BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 3772ae930e0fSTejun Heo !system_unbound_wq || !system_freezable_wq); 37736ee0578bSSuresh Siddha return 0; 37741da177e4SLinus Torvalds } 37756ee0578bSSuresh Siddha early_initcall(init_workqueues); 3776