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 */ 127ec22ca5eSTejun Heo unsigned 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 */ 172e904e6c2STejun Heo } __aligned(1 << WORK_STRUCT_FLAG_BITS); 1731da177e4SLinus Torvalds 1741da177e4SLinus Torvalds /* 17573f53c4aSTejun Heo * Structure used to wait for workqueue flush. 17673f53c4aSTejun Heo */ 17773f53c4aSTejun Heo struct wq_flusher { 17873f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 17973f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 18073f53c4aSTejun Heo struct completion done; /* flush completion */ 18173f53c4aSTejun Heo }; 1821da177e4SLinus Torvalds 18373f53c4aSTejun Heo /* 184f2e005aaSTejun Heo * All cpumasks are assumed to be always set on UP and thus can't be 185f2e005aaSTejun Heo * used to determine whether there's something to be done. 186f2e005aaSTejun Heo */ 187f2e005aaSTejun Heo #ifdef CONFIG_SMP 188f2e005aaSTejun Heo typedef cpumask_var_t mayday_mask_t; 189f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) \ 190f2e005aaSTejun Heo cpumask_test_and_set_cpu((cpu), (mask)) 191f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) 192f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) 1939c37547aSTejun Heo #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) 194f2e005aaSTejun Heo #define free_mayday_mask(mask) free_cpumask_var((mask)) 195f2e005aaSTejun Heo #else 196f2e005aaSTejun Heo typedef unsigned long mayday_mask_t; 197f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) 198f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) 199f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) 200f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) true 201f2e005aaSTejun Heo #define free_mayday_mask(mask) do { } while (0) 202f2e005aaSTejun Heo #endif 2031da177e4SLinus Torvalds 2041da177e4SLinus Torvalds /* 2051da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 2061da177e4SLinus Torvalds * per-CPU workqueues: 2071da177e4SLinus Torvalds */ 2081da177e4SLinus Torvalds struct workqueue_struct { 2099c5a2ba7STejun Heo unsigned int flags; /* W: WQ_* flags */ 210bdbc5dd7STejun Heo union { 211112202d9STejun Heo struct pool_workqueue __percpu *pcpu; 212112202d9STejun Heo struct pool_workqueue *single; 213bdbc5dd7STejun Heo unsigned long v; 214112202d9STejun Heo } pool_wq; /* I: pwq's */ 2154690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 21673f53c4aSTejun Heo 21773f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 21873f53c4aSTejun Heo int work_color; /* F: current work color */ 21973f53c4aSTejun Heo int flush_color; /* F: current flush color */ 220112202d9STejun Heo atomic_t nr_pwqs_to_flush; /* flush in progress */ 22173f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 22273f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 22373f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 22473f53c4aSTejun Heo 225f2e005aaSTejun Heo mayday_mask_t mayday_mask; /* cpus requesting rescue */ 226e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 227e22bee78STejun Heo 2289c5a2ba7STejun Heo int nr_drainers; /* W: drain in progress */ 229112202d9STejun Heo int saved_max_active; /* W: saved pwq max_active */ 2304e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2314e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2324e6045f1SJohannes Berg #endif 233b196be89STejun Heo char name[]; /* I: workqueue name */ 2341da177e4SLinus Torvalds }; 2351da177e4SLinus Torvalds 236e904e6c2STejun Heo static struct kmem_cache *pwq_cache; 237e904e6c2STejun Heo 238d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 239d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 240044c782cSValentin Ilie struct workqueue_struct *system_highpri_wq __read_mostly; 2411aabe902SJoonsoo Kim EXPORT_SYMBOL_GPL(system_highpri_wq); 242044c782cSValentin Ilie struct workqueue_struct *system_long_wq __read_mostly; 243d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 244044c782cSValentin Ilie struct workqueue_struct *system_unbound_wq __read_mostly; 245f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 246044c782cSValentin Ilie struct workqueue_struct *system_freezable_wq __read_mostly; 24724d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 248d320c038STejun Heo 24997bd2347STejun Heo #define CREATE_TRACE_POINTS 25097bd2347STejun Heo #include <trace/events/workqueue.h> 25197bd2347STejun Heo 25238db41d9STejun Heo #define for_each_std_worker_pool(pool, cpu) \ 253a60dc39cSTejun Heo for ((pool) = &std_worker_pools(cpu)[0]; \ 254a60dc39cSTejun Heo (pool) < &std_worker_pools(cpu)[NR_STD_WORKER_POOLS]; (pool)++) 2554ce62e9eSTejun Heo 256b67bfe0dSSasha Levin #define for_each_busy_worker(worker, i, pool) \ 257b67bfe0dSSasha Levin hash_for_each(pool->busy_hash, i, worker, hentry) 258db7bccf4STejun Heo 259706026c2STejun Heo static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, 260f3421797STejun Heo unsigned int sw) 261f3421797STejun Heo { 262f3421797STejun Heo if (cpu < nr_cpu_ids) { 263f3421797STejun Heo if (sw & 1) { 264f3421797STejun Heo cpu = cpumask_next(cpu, mask); 265f3421797STejun Heo if (cpu < nr_cpu_ids) 266f3421797STejun Heo return cpu; 267f3421797STejun Heo } 268f3421797STejun Heo if (sw & 2) 269f3421797STejun Heo return WORK_CPU_UNBOUND; 270f3421797STejun Heo } 2716be19588SLai Jiangshan return WORK_CPU_END; 272f3421797STejun Heo } 273f3421797STejun Heo 274112202d9STejun Heo static inline int __next_pwq_cpu(int cpu, const struct cpumask *mask, 275f3421797STejun Heo struct workqueue_struct *wq) 276f3421797STejun Heo { 277706026c2STejun Heo return __next_wq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); 278f3421797STejun Heo } 279f3421797STejun Heo 28009884951STejun Heo /* 28109884951STejun Heo * CPU iterators 28209884951STejun Heo * 283706026c2STejun Heo * An extra cpu number is defined using an invalid cpu number 28409884951STejun Heo * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any 285706026c2STejun Heo * specific CPU. The following iterators are similar to for_each_*_cpu() 286706026c2STejun Heo * iterators but also considers the unbound CPU. 28709884951STejun Heo * 288706026c2STejun Heo * for_each_wq_cpu() : possible CPUs + WORK_CPU_UNBOUND 289706026c2STejun Heo * for_each_online_wq_cpu() : online CPUs + WORK_CPU_UNBOUND 290112202d9STejun Heo * for_each_pwq_cpu() : possible CPUs for bound workqueues, 29109884951STejun Heo * WORK_CPU_UNBOUND for unbound workqueues 29209884951STejun Heo */ 293706026c2STejun Heo #define for_each_wq_cpu(cpu) \ 294706026c2STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, 3); \ 2956be19588SLai Jiangshan (cpu) < WORK_CPU_END; \ 296706026c2STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, 3)) 297f3421797STejun Heo 298706026c2STejun Heo #define for_each_online_wq_cpu(cpu) \ 299706026c2STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_online_mask, 3); \ 3006be19588SLai Jiangshan (cpu) < WORK_CPU_END; \ 301706026c2STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_online_mask, 3)) 302f3421797STejun Heo 303112202d9STejun Heo #define for_each_pwq_cpu(cpu, wq) \ 304112202d9STejun Heo for ((cpu) = __next_pwq_cpu(-1, cpu_possible_mask, (wq)); \ 3056be19588SLai Jiangshan (cpu) < WORK_CPU_END; \ 306112202d9STejun Heo (cpu) = __next_pwq_cpu((cpu), cpu_possible_mask, (wq))) 307f3421797STejun Heo 308dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 309dc186ad7SThomas Gleixner 310dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 311dc186ad7SThomas Gleixner 31299777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 31399777288SStanislaw Gruszka { 31499777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 31599777288SStanislaw Gruszka } 31699777288SStanislaw Gruszka 317dc186ad7SThomas Gleixner /* 318dc186ad7SThomas Gleixner * fixup_init is called when: 319dc186ad7SThomas Gleixner * - an active object is initialized 320dc186ad7SThomas Gleixner */ 321dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 322dc186ad7SThomas Gleixner { 323dc186ad7SThomas Gleixner struct work_struct *work = addr; 324dc186ad7SThomas Gleixner 325dc186ad7SThomas Gleixner switch (state) { 326dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 327dc186ad7SThomas Gleixner cancel_work_sync(work); 328dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 329dc186ad7SThomas Gleixner return 1; 330dc186ad7SThomas Gleixner default: 331dc186ad7SThomas Gleixner return 0; 332dc186ad7SThomas Gleixner } 333dc186ad7SThomas Gleixner } 334dc186ad7SThomas Gleixner 335dc186ad7SThomas Gleixner /* 336dc186ad7SThomas Gleixner * fixup_activate is called when: 337dc186ad7SThomas Gleixner * - an active object is activated 338dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 339dc186ad7SThomas Gleixner */ 340dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 341dc186ad7SThomas Gleixner { 342dc186ad7SThomas Gleixner struct work_struct *work = addr; 343dc186ad7SThomas Gleixner 344dc186ad7SThomas Gleixner switch (state) { 345dc186ad7SThomas Gleixner 346dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 347dc186ad7SThomas Gleixner /* 348dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 349dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 350dc186ad7SThomas Gleixner * is tracked in the object tracker. 351dc186ad7SThomas Gleixner */ 35222df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 353dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 354dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 355dc186ad7SThomas Gleixner return 0; 356dc186ad7SThomas Gleixner } 357dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 358dc186ad7SThomas Gleixner return 0; 359dc186ad7SThomas Gleixner 360dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 361dc186ad7SThomas Gleixner WARN_ON(1); 362dc186ad7SThomas Gleixner 363dc186ad7SThomas Gleixner default: 364dc186ad7SThomas Gleixner return 0; 365dc186ad7SThomas Gleixner } 366dc186ad7SThomas Gleixner } 367dc186ad7SThomas Gleixner 368dc186ad7SThomas Gleixner /* 369dc186ad7SThomas Gleixner * fixup_free is called when: 370dc186ad7SThomas Gleixner * - an active object is freed 371dc186ad7SThomas Gleixner */ 372dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 373dc186ad7SThomas Gleixner { 374dc186ad7SThomas Gleixner struct work_struct *work = addr; 375dc186ad7SThomas Gleixner 376dc186ad7SThomas Gleixner switch (state) { 377dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 378dc186ad7SThomas Gleixner cancel_work_sync(work); 379dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 380dc186ad7SThomas Gleixner return 1; 381dc186ad7SThomas Gleixner default: 382dc186ad7SThomas Gleixner return 0; 383dc186ad7SThomas Gleixner } 384dc186ad7SThomas Gleixner } 385dc186ad7SThomas Gleixner 386dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 387dc186ad7SThomas Gleixner .name = "work_struct", 38899777288SStanislaw Gruszka .debug_hint = work_debug_hint, 389dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 390dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 391dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 392dc186ad7SThomas Gleixner }; 393dc186ad7SThomas Gleixner 394dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 395dc186ad7SThomas Gleixner { 396dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 397dc186ad7SThomas Gleixner } 398dc186ad7SThomas Gleixner 399dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 400dc186ad7SThomas Gleixner { 401dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 402dc186ad7SThomas Gleixner } 403dc186ad7SThomas Gleixner 404dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 405dc186ad7SThomas Gleixner { 406dc186ad7SThomas Gleixner if (onstack) 407dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 408dc186ad7SThomas Gleixner else 409dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 410dc186ad7SThomas Gleixner } 411dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 412dc186ad7SThomas Gleixner 413dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 414dc186ad7SThomas Gleixner { 415dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 416dc186ad7SThomas Gleixner } 417dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 418dc186ad7SThomas Gleixner 419dc186ad7SThomas Gleixner #else 420dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 421dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 422dc186ad7SThomas Gleixner #endif 423dc186ad7SThomas Gleixner 42495402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 42595402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 4261da177e4SLinus Torvalds static LIST_HEAD(workqueues); 427a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 4281da177e4SLinus Torvalds 42914441960SOleg Nesterov /* 430e19e397aSTejun Heo * The CPU and unbound standard worker pools. The unbound ones have 431e19e397aSTejun Heo * POOL_DISASSOCIATED set, and their workers have WORKER_UNBOUND set. 43214441960SOleg Nesterov */ 433e19e397aSTejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], 434a60dc39cSTejun Heo cpu_std_worker_pools); 435a60dc39cSTejun Heo static struct worker_pool unbound_std_worker_pools[NR_STD_WORKER_POOLS]; 436f3421797STejun Heo 4379daf9e67STejun Heo /* idr of all pools */ 4389daf9e67STejun Heo static DEFINE_MUTEX(worker_pool_idr_mutex); 4399daf9e67STejun Heo static DEFINE_IDR(worker_pool_idr); 4409daf9e67STejun Heo 441c34056a3STejun Heo static int worker_thread(void *__worker); 4421da177e4SLinus Torvalds 443a60dc39cSTejun Heo static struct worker_pool *std_worker_pools(int cpu) 4441da177e4SLinus Torvalds { 445f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 446a60dc39cSTejun Heo return per_cpu(cpu_std_worker_pools, cpu); 447f3421797STejun Heo else 448a60dc39cSTejun Heo return unbound_std_worker_pools; 4491da177e4SLinus Torvalds } 4501da177e4SLinus Torvalds 4514e8f0a60STejun Heo static int std_worker_pool_pri(struct worker_pool *pool) 4524e8f0a60STejun Heo { 453a60dc39cSTejun Heo return pool - std_worker_pools(pool->cpu); 4544e8f0a60STejun Heo } 4554e8f0a60STejun Heo 4569daf9e67STejun Heo /* allocate ID and assign it to @pool */ 4579daf9e67STejun Heo static int worker_pool_assign_id(struct worker_pool *pool) 4589daf9e67STejun Heo { 4599daf9e67STejun Heo int ret; 4609daf9e67STejun Heo 4619daf9e67STejun Heo mutex_lock(&worker_pool_idr_mutex); 4629daf9e67STejun Heo idr_pre_get(&worker_pool_idr, GFP_KERNEL); 4639daf9e67STejun Heo ret = idr_get_new(&worker_pool_idr, pool, &pool->id); 4649daf9e67STejun Heo mutex_unlock(&worker_pool_idr_mutex); 4659daf9e67STejun Heo 4669daf9e67STejun Heo return ret; 4679daf9e67STejun Heo } 4689daf9e67STejun Heo 4697c3eed5cSTejun Heo /* 4707c3eed5cSTejun Heo * Lookup worker_pool by id. The idr currently is built during boot and 4717c3eed5cSTejun Heo * never modified. Don't worry about locking for now. 4727c3eed5cSTejun Heo */ 4737c3eed5cSTejun Heo static struct worker_pool *worker_pool_by_id(int pool_id) 4747c3eed5cSTejun Heo { 4757c3eed5cSTejun Heo return idr_find(&worker_pool_idr, pool_id); 4767c3eed5cSTejun Heo } 4777c3eed5cSTejun Heo 478d565ed63STejun Heo static struct worker_pool *get_std_worker_pool(int cpu, bool highpri) 479d565ed63STejun Heo { 480a60dc39cSTejun Heo struct worker_pool *pools = std_worker_pools(cpu); 481d565ed63STejun Heo 482a60dc39cSTejun Heo return &pools[highpri]; 483d565ed63STejun Heo } 484d565ed63STejun Heo 485112202d9STejun Heo static struct pool_workqueue *get_pwq(unsigned int cpu, 4864690c4abSTejun Heo struct workqueue_struct *wq) 487a848e3b6SOleg Nesterov { 488f3421797STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 489e06ffa1eSLai Jiangshan if (likely(cpu < nr_cpu_ids)) 490112202d9STejun Heo return per_cpu_ptr(wq->pool_wq.pcpu, cpu); 491f3421797STejun Heo } else if (likely(cpu == WORK_CPU_UNBOUND)) 492112202d9STejun Heo return wq->pool_wq.single; 493f3421797STejun Heo return NULL; 494f3421797STejun Heo } 495a848e3b6SOleg Nesterov 49673f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 49773f53c4aSTejun Heo { 49873f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 49973f53c4aSTejun Heo } 50073f53c4aSTejun Heo 50173f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 50273f53c4aSTejun Heo { 50373f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 50473f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 50573f53c4aSTejun Heo } 50673f53c4aSTejun Heo 50773f53c4aSTejun Heo static int work_next_color(int color) 50873f53c4aSTejun Heo { 50973f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 510b1f4ec17SOleg Nesterov } 511b1f4ec17SOleg Nesterov 5124594bf15SDavid Howells /* 513112202d9STejun Heo * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data 514112202d9STejun Heo * contain the pointer to the queued pwq. Once execution starts, the flag 5157c3eed5cSTejun Heo * is cleared and the high bits contain OFFQ flags and pool ID. 5167a22ad75STejun Heo * 517112202d9STejun Heo * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() 518112202d9STejun Heo * and clear_work_data() can be used to set the pwq, pool or clear 519bbb68dfaSTejun Heo * work->data. These functions should only be called while the work is 520bbb68dfaSTejun Heo * owned - ie. while the PENDING bit is set. 5217a22ad75STejun Heo * 522112202d9STejun Heo * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq 5237c3eed5cSTejun Heo * corresponding to a work. Pool is available once the work has been 524112202d9STejun Heo * queued anywhere after initialization until it is sync canceled. pwq is 5257c3eed5cSTejun Heo * available only while the work item is queued. 526bbb68dfaSTejun Heo * 527bbb68dfaSTejun Heo * %WORK_OFFQ_CANCELING is used to mark a work item which is being 528bbb68dfaSTejun Heo * canceled. While being canceled, a work item may have its PENDING set 529bbb68dfaSTejun Heo * but stay off timer and worklist for arbitrarily long and nobody should 530bbb68dfaSTejun Heo * try to steal the PENDING bit. 5314594bf15SDavid Howells */ 5327a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 5337a22ad75STejun Heo unsigned long flags) 5347a22ad75STejun Heo { 5356183c009STejun Heo WARN_ON_ONCE(!work_pending(work)); 5367a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 5377a22ad75STejun Heo } 5387a22ad75STejun Heo 539112202d9STejun Heo static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, 5404690c4abSTejun Heo unsigned long extra_flags) 541365970a1SDavid Howells { 542112202d9STejun Heo set_work_data(work, (unsigned long)pwq, 543112202d9STejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); 544365970a1SDavid Howells } 545365970a1SDavid Howells 5464468a00fSLai Jiangshan static void set_work_pool_and_keep_pending(struct work_struct *work, 5474468a00fSLai Jiangshan int pool_id) 5484468a00fSLai Jiangshan { 5494468a00fSLai Jiangshan set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 5504468a00fSLai Jiangshan WORK_STRUCT_PENDING); 5514468a00fSLai Jiangshan } 5524468a00fSLai Jiangshan 5537c3eed5cSTejun Heo static void set_work_pool_and_clear_pending(struct work_struct *work, 5547c3eed5cSTejun Heo int pool_id) 5554d707b9fSOleg Nesterov { 55623657bb1STejun Heo /* 55723657bb1STejun Heo * The following wmb is paired with the implied mb in 55823657bb1STejun Heo * test_and_set_bit(PENDING) and ensures all updates to @work made 55923657bb1STejun Heo * here are visible to and precede any updates by the next PENDING 56023657bb1STejun Heo * owner. 56123657bb1STejun Heo */ 56223657bb1STejun Heo smp_wmb(); 5637c3eed5cSTejun Heo set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); 5644d707b9fSOleg Nesterov } 5654d707b9fSOleg Nesterov 5667a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 567365970a1SDavid Howells { 5687c3eed5cSTejun Heo smp_wmb(); /* see set_work_pool_and_clear_pending() */ 5697c3eed5cSTejun Heo set_work_data(work, WORK_STRUCT_NO_POOL, 0); 5707a22ad75STejun Heo } 5717a22ad75STejun Heo 572112202d9STejun Heo static struct pool_workqueue *get_work_pwq(struct work_struct *work) 5737a22ad75STejun Heo { 574e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5757a22ad75STejun Heo 576112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 577e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 578e120153dSTejun Heo else 579e120153dSTejun Heo return NULL; 5807a22ad75STejun Heo } 5817a22ad75STejun Heo 5827c3eed5cSTejun Heo /** 5837c3eed5cSTejun Heo * get_work_pool - return the worker_pool a given work was associated with 5847c3eed5cSTejun Heo * @work: the work item of interest 5857c3eed5cSTejun Heo * 5867c3eed5cSTejun Heo * Return the worker_pool @work was last associated with. %NULL if none. 5877c3eed5cSTejun Heo */ 5887c3eed5cSTejun Heo static struct worker_pool *get_work_pool(struct work_struct *work) 5897a22ad75STejun Heo { 590e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5917c3eed5cSTejun Heo struct worker_pool *pool; 5927c3eed5cSTejun Heo int pool_id; 5937a22ad75STejun Heo 594112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 595112202d9STejun Heo return ((struct pool_workqueue *) 5967c3eed5cSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->pool; 5977a22ad75STejun Heo 5987c3eed5cSTejun Heo pool_id = data >> WORK_OFFQ_POOL_SHIFT; 5997c3eed5cSTejun Heo if (pool_id == WORK_OFFQ_POOL_NONE) 6007a22ad75STejun Heo return NULL; 6017a22ad75STejun Heo 6027c3eed5cSTejun Heo pool = worker_pool_by_id(pool_id); 6037c3eed5cSTejun Heo WARN_ON_ONCE(!pool); 6047c3eed5cSTejun Heo return pool; 6057c3eed5cSTejun Heo } 6067c3eed5cSTejun Heo 6077c3eed5cSTejun Heo /** 6087c3eed5cSTejun Heo * get_work_pool_id - return the worker pool ID a given work is associated with 6097c3eed5cSTejun Heo * @work: the work item of interest 6107c3eed5cSTejun Heo * 6117c3eed5cSTejun Heo * Return the worker_pool ID @work was last associated with. 6127c3eed5cSTejun Heo * %WORK_OFFQ_POOL_NONE if none. 6137c3eed5cSTejun Heo */ 6147c3eed5cSTejun Heo static int get_work_pool_id(struct work_struct *work) 6157c3eed5cSTejun Heo { 61654d5b7d0SLai Jiangshan unsigned long data = atomic_long_read(&work->data); 6177c3eed5cSTejun Heo 618112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 619112202d9STejun Heo return ((struct pool_workqueue *) 62054d5b7d0SLai Jiangshan (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; 62154d5b7d0SLai Jiangshan 62254d5b7d0SLai Jiangshan return data >> WORK_OFFQ_POOL_SHIFT; 6237c3eed5cSTejun Heo } 6247c3eed5cSTejun Heo 625bbb68dfaSTejun Heo static void mark_work_canceling(struct work_struct *work) 626bbb68dfaSTejun Heo { 6277c3eed5cSTejun Heo unsigned long pool_id = get_work_pool_id(work); 628bbb68dfaSTejun Heo 6297c3eed5cSTejun Heo pool_id <<= WORK_OFFQ_POOL_SHIFT; 6307c3eed5cSTejun Heo set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); 631bbb68dfaSTejun Heo } 632bbb68dfaSTejun Heo 633bbb68dfaSTejun Heo static bool work_is_canceling(struct work_struct *work) 634bbb68dfaSTejun Heo { 635bbb68dfaSTejun Heo unsigned long data = atomic_long_read(&work->data); 636bbb68dfaSTejun Heo 637112202d9STejun Heo return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); 638bbb68dfaSTejun Heo } 639bbb68dfaSTejun Heo 640e22bee78STejun Heo /* 6413270476aSTejun Heo * Policy functions. These define the policies on how the global worker 6423270476aSTejun Heo * pools are managed. Unless noted otherwise, these functions assume that 643d565ed63STejun Heo * they're being called with pool->lock held. 644e22bee78STejun Heo */ 645e22bee78STejun Heo 64663d95a91STejun Heo static bool __need_more_worker(struct worker_pool *pool) 647649027d7STejun Heo { 648e19e397aSTejun Heo return !atomic_read(&pool->nr_running); 649649027d7STejun Heo } 650649027d7STejun Heo 651e22bee78STejun Heo /* 652e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 653e22bee78STejun Heo * running workers. 654974271c4STejun Heo * 655974271c4STejun Heo * Note that, because unbound workers never contribute to nr_running, this 656706026c2STejun Heo * function will always return %true for unbound pools as long as the 657974271c4STejun Heo * worklist isn't empty. 658e22bee78STejun Heo */ 65963d95a91STejun Heo static bool need_more_worker(struct worker_pool *pool) 660e22bee78STejun Heo { 66163d95a91STejun Heo return !list_empty(&pool->worklist) && __need_more_worker(pool); 662e22bee78STejun Heo } 663e22bee78STejun Heo 664e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 66563d95a91STejun Heo static bool may_start_working(struct worker_pool *pool) 666e22bee78STejun Heo { 66763d95a91STejun Heo return pool->nr_idle; 668e22bee78STejun Heo } 669e22bee78STejun Heo 670e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 67163d95a91STejun Heo static bool keep_working(struct worker_pool *pool) 672e22bee78STejun Heo { 673e19e397aSTejun Heo return !list_empty(&pool->worklist) && 674e19e397aSTejun Heo atomic_read(&pool->nr_running) <= 1; 675e22bee78STejun Heo } 676e22bee78STejun Heo 677e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 67863d95a91STejun Heo static bool need_to_create_worker(struct worker_pool *pool) 679e22bee78STejun Heo { 68063d95a91STejun Heo return need_more_worker(pool) && !may_start_working(pool); 681e22bee78STejun Heo } 682e22bee78STejun Heo 683e22bee78STejun Heo /* Do I need to be the manager? */ 68463d95a91STejun Heo static bool need_to_manage_workers(struct worker_pool *pool) 685e22bee78STejun Heo { 68663d95a91STejun Heo return need_to_create_worker(pool) || 68711ebea50STejun Heo (pool->flags & POOL_MANAGE_WORKERS); 688e22bee78STejun Heo } 689e22bee78STejun Heo 690e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 69163d95a91STejun Heo static bool too_many_workers(struct worker_pool *pool) 692e22bee78STejun Heo { 693552a37e9SLai Jiangshan bool managing = pool->flags & POOL_MANAGING_WORKERS; 69463d95a91STejun Heo int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 69563d95a91STejun Heo int nr_busy = pool->nr_workers - nr_idle; 696e22bee78STejun Heo 697ea1abd61SLai Jiangshan /* 698ea1abd61SLai Jiangshan * nr_idle and idle_list may disagree if idle rebinding is in 699ea1abd61SLai Jiangshan * progress. Never return %true if idle_list is empty. 700ea1abd61SLai Jiangshan */ 701ea1abd61SLai Jiangshan if (list_empty(&pool->idle_list)) 702ea1abd61SLai Jiangshan return false; 703ea1abd61SLai Jiangshan 704e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 705e22bee78STejun Heo } 706e22bee78STejun Heo 707e22bee78STejun Heo /* 708e22bee78STejun Heo * Wake up functions. 709e22bee78STejun Heo */ 710e22bee78STejun Heo 7117e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 71263d95a91STejun Heo static struct worker *first_worker(struct worker_pool *pool) 7137e11629dSTejun Heo { 71463d95a91STejun Heo if (unlikely(list_empty(&pool->idle_list))) 7157e11629dSTejun Heo return NULL; 7167e11629dSTejun Heo 71763d95a91STejun Heo return list_first_entry(&pool->idle_list, struct worker, entry); 7187e11629dSTejun Heo } 7197e11629dSTejun Heo 7207e11629dSTejun Heo /** 7217e11629dSTejun Heo * wake_up_worker - wake up an idle worker 72263d95a91STejun Heo * @pool: worker pool to wake worker from 7237e11629dSTejun Heo * 72463d95a91STejun Heo * Wake up the first idle worker of @pool. 7257e11629dSTejun Heo * 7267e11629dSTejun Heo * CONTEXT: 727d565ed63STejun Heo * spin_lock_irq(pool->lock). 7287e11629dSTejun Heo */ 72963d95a91STejun Heo static void wake_up_worker(struct worker_pool *pool) 7307e11629dSTejun Heo { 73163d95a91STejun Heo struct worker *worker = first_worker(pool); 7327e11629dSTejun Heo 7337e11629dSTejun Heo if (likely(worker)) 7347e11629dSTejun Heo wake_up_process(worker->task); 7357e11629dSTejun Heo } 7367e11629dSTejun Heo 7374690c4abSTejun Heo /** 738e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 739e22bee78STejun Heo * @task: task waking up 740e22bee78STejun Heo * @cpu: CPU @task is waking up to 741e22bee78STejun Heo * 742e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 743e22bee78STejun Heo * being awoken. 744e22bee78STejun Heo * 745e22bee78STejun Heo * CONTEXT: 746e22bee78STejun Heo * spin_lock_irq(rq->lock) 747e22bee78STejun Heo */ 748e22bee78STejun Heo void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) 749e22bee78STejun Heo { 750e22bee78STejun Heo struct worker *worker = kthread_data(task); 751e22bee78STejun Heo 75236576000SJoonsoo Kim if (!(worker->flags & WORKER_NOT_RUNNING)) { 753ec22ca5eSTejun Heo WARN_ON_ONCE(worker->pool->cpu != cpu); 754e19e397aSTejun Heo atomic_inc(&worker->pool->nr_running); 755e22bee78STejun Heo } 75636576000SJoonsoo Kim } 757e22bee78STejun Heo 758e22bee78STejun Heo /** 759e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 760e22bee78STejun Heo * @task: task going to sleep 761e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 762e22bee78STejun Heo * 763e22bee78STejun Heo * This function is called during schedule() when a busy worker is 764e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 765e22bee78STejun Heo * returning pointer to its task. 766e22bee78STejun Heo * 767e22bee78STejun Heo * CONTEXT: 768e22bee78STejun Heo * spin_lock_irq(rq->lock) 769e22bee78STejun Heo * 770e22bee78STejun Heo * RETURNS: 771e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 772e22bee78STejun Heo */ 773e22bee78STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, 774e22bee78STejun Heo unsigned int cpu) 775e22bee78STejun Heo { 776e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 777111c225aSTejun Heo struct worker_pool *pool; 778e22bee78STejun Heo 779111c225aSTejun Heo /* 780111c225aSTejun Heo * Rescuers, which may not have all the fields set up like normal 781111c225aSTejun Heo * workers, also reach here, let's not access anything before 782111c225aSTejun Heo * checking NOT_RUNNING. 783111c225aSTejun Heo */ 7842d64672eSSteven Rostedt if (worker->flags & WORKER_NOT_RUNNING) 785e22bee78STejun Heo return NULL; 786e22bee78STejun Heo 787111c225aSTejun Heo pool = worker->pool; 788111c225aSTejun Heo 789e22bee78STejun Heo /* this can only happen on the local cpu */ 7906183c009STejun Heo if (WARN_ON_ONCE(cpu != raw_smp_processor_id())) 7916183c009STejun Heo return NULL; 792e22bee78STejun Heo 793e22bee78STejun Heo /* 794e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 795e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 796e22bee78STejun Heo * Please read comment there. 797e22bee78STejun Heo * 798628c78e7STejun Heo * NOT_RUNNING is clear. This means that we're bound to and 799628c78e7STejun Heo * running on the local cpu w/ rq lock held and preemption 800628c78e7STejun Heo * disabled, which in turn means that none else could be 801d565ed63STejun Heo * manipulating idle_list, so dereferencing idle_list without pool 802628c78e7STejun Heo * lock is safe. 803e22bee78STejun Heo */ 804e19e397aSTejun Heo if (atomic_dec_and_test(&pool->nr_running) && 805e19e397aSTejun Heo !list_empty(&pool->worklist)) 80663d95a91STejun Heo to_wakeup = first_worker(pool); 807e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 808e22bee78STejun Heo } 809e22bee78STejun Heo 810e22bee78STejun Heo /** 811e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 812cb444766STejun Heo * @worker: self 813d302f017STejun Heo * @flags: flags to set 814d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 815d302f017STejun Heo * 816e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 817e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 818e22bee78STejun Heo * woken up. 819d302f017STejun Heo * 820cb444766STejun Heo * CONTEXT: 821d565ed63STejun Heo * spin_lock_irq(pool->lock) 822d302f017STejun Heo */ 823d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 824d302f017STejun Heo bool wakeup) 825d302f017STejun Heo { 826bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 827e22bee78STejun Heo 828cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 829cb444766STejun Heo 830e22bee78STejun Heo /* 831e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 832e22bee78STejun Heo * wake up an idle worker as necessary if requested by 833e22bee78STejun Heo * @wakeup. 834e22bee78STejun Heo */ 835e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 836e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 837e22bee78STejun Heo if (wakeup) { 838e19e397aSTejun Heo if (atomic_dec_and_test(&pool->nr_running) && 839bd7bdd43STejun Heo !list_empty(&pool->worklist)) 84063d95a91STejun Heo wake_up_worker(pool); 841e22bee78STejun Heo } else 842e19e397aSTejun Heo atomic_dec(&pool->nr_running); 843e22bee78STejun Heo } 844e22bee78STejun Heo 845d302f017STejun Heo worker->flags |= flags; 846d302f017STejun Heo } 847d302f017STejun Heo 848d302f017STejun Heo /** 849e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 850cb444766STejun Heo * @worker: self 851d302f017STejun Heo * @flags: flags to clear 852d302f017STejun Heo * 853e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 854d302f017STejun Heo * 855cb444766STejun Heo * CONTEXT: 856d565ed63STejun Heo * spin_lock_irq(pool->lock) 857d302f017STejun Heo */ 858d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 859d302f017STejun Heo { 86063d95a91STejun Heo struct worker_pool *pool = worker->pool; 861e22bee78STejun Heo unsigned int oflags = worker->flags; 862e22bee78STejun Heo 863cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 864cb444766STejun Heo 865d302f017STejun Heo worker->flags &= ~flags; 866e22bee78STejun Heo 86742c025f3STejun Heo /* 86842c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 86942c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 87042c025f3STejun Heo * of multiple flags, not a single flag. 87142c025f3STejun Heo */ 872e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 873e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 874e19e397aSTejun Heo atomic_inc(&pool->nr_running); 875d302f017STejun Heo } 876d302f017STejun Heo 877d302f017STejun Heo /** 8788cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 879c9e7cf27STejun Heo * @pool: pool of interest 8808cca0eeaSTejun Heo * @work: work to find worker for 8818cca0eeaSTejun Heo * 882c9e7cf27STejun Heo * Find a worker which is executing @work on @pool by searching 883c9e7cf27STejun Heo * @pool->busy_hash which is keyed by the address of @work. For a worker 884a2c1c57bSTejun Heo * to match, its current execution should match the address of @work and 885a2c1c57bSTejun Heo * its work function. This is to avoid unwanted dependency between 886a2c1c57bSTejun Heo * unrelated work executions through a work item being recycled while still 887a2c1c57bSTejun Heo * being executed. 888a2c1c57bSTejun Heo * 889a2c1c57bSTejun Heo * This is a bit tricky. A work item may be freed once its execution 890a2c1c57bSTejun Heo * starts and nothing prevents the freed area from being recycled for 891a2c1c57bSTejun Heo * another work item. If the same work item address ends up being reused 892a2c1c57bSTejun Heo * before the original execution finishes, workqueue will identify the 893a2c1c57bSTejun Heo * recycled work item as currently executing and make it wait until the 894a2c1c57bSTejun Heo * current execution finishes, introducing an unwanted dependency. 895a2c1c57bSTejun Heo * 896a2c1c57bSTejun Heo * This function checks the work item address, work function and workqueue 897a2c1c57bSTejun Heo * to avoid false positives. Note that this isn't complete as one may 898a2c1c57bSTejun Heo * construct a work function which can introduce dependency onto itself 899a2c1c57bSTejun Heo * through a recycled work item. Well, if somebody wants to shoot oneself 900a2c1c57bSTejun Heo * in the foot that badly, there's only so much we can do, and if such 901a2c1c57bSTejun Heo * deadlock actually occurs, it should be easy to locate the culprit work 902a2c1c57bSTejun Heo * function. 9038cca0eeaSTejun Heo * 9048cca0eeaSTejun Heo * CONTEXT: 905d565ed63STejun Heo * spin_lock_irq(pool->lock). 9068cca0eeaSTejun Heo * 9078cca0eeaSTejun Heo * RETURNS: 9088cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 9098cca0eeaSTejun Heo * otherwise. 9108cca0eeaSTejun Heo */ 911c9e7cf27STejun Heo static struct worker *find_worker_executing_work(struct worker_pool *pool, 9128cca0eeaSTejun Heo struct work_struct *work) 9138cca0eeaSTejun Heo { 91442f8570fSSasha Levin struct worker *worker; 91542f8570fSSasha Levin 916b67bfe0dSSasha Levin hash_for_each_possible(pool->busy_hash, worker, hentry, 917a2c1c57bSTejun Heo (unsigned long)work) 918a2c1c57bSTejun Heo if (worker->current_work == work && 919a2c1c57bSTejun Heo worker->current_func == work->func) 92042f8570fSSasha Levin return worker; 92142f8570fSSasha Levin 92242f8570fSSasha Levin return NULL; 9238cca0eeaSTejun Heo } 9248cca0eeaSTejun Heo 9258cca0eeaSTejun Heo /** 926bf4ede01STejun Heo * move_linked_works - move linked works to a list 927bf4ede01STejun Heo * @work: start of series of works to be scheduled 928bf4ede01STejun Heo * @head: target list to append @work to 929bf4ede01STejun Heo * @nextp: out paramter for nested worklist walking 930bf4ede01STejun Heo * 931bf4ede01STejun Heo * Schedule linked works starting from @work to @head. Work series to 932bf4ede01STejun Heo * be scheduled starts at @work and includes any consecutive work with 933bf4ede01STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 934bf4ede01STejun Heo * 935bf4ede01STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 936bf4ede01STejun Heo * the last scheduled work. This allows move_linked_works() to be 937bf4ede01STejun Heo * nested inside outer list_for_each_entry_safe(). 938bf4ede01STejun Heo * 939bf4ede01STejun Heo * CONTEXT: 940d565ed63STejun Heo * spin_lock_irq(pool->lock). 941bf4ede01STejun Heo */ 942bf4ede01STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 943bf4ede01STejun Heo struct work_struct **nextp) 944bf4ede01STejun Heo { 945bf4ede01STejun Heo struct work_struct *n; 946bf4ede01STejun Heo 947bf4ede01STejun Heo /* 948bf4ede01STejun Heo * Linked worklist will always end before the end of the list, 949bf4ede01STejun Heo * use NULL for list head. 950bf4ede01STejun Heo */ 951bf4ede01STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 952bf4ede01STejun Heo list_move_tail(&work->entry, head); 953bf4ede01STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 954bf4ede01STejun Heo break; 955bf4ede01STejun Heo } 956bf4ede01STejun Heo 957bf4ede01STejun Heo /* 958bf4ede01STejun Heo * If we're already inside safe list traversal and have moved 959bf4ede01STejun Heo * multiple works to the scheduled queue, the next position 960bf4ede01STejun Heo * needs to be updated. 961bf4ede01STejun Heo */ 962bf4ede01STejun Heo if (nextp) 963bf4ede01STejun Heo *nextp = n; 964bf4ede01STejun Heo } 965bf4ede01STejun Heo 966112202d9STejun Heo static void pwq_activate_delayed_work(struct work_struct *work) 967bf4ede01STejun Heo { 968112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 969bf4ede01STejun Heo 970bf4ede01STejun Heo trace_workqueue_activate_work(work); 971112202d9STejun Heo move_linked_works(work, &pwq->pool->worklist, NULL); 972bf4ede01STejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 973112202d9STejun Heo pwq->nr_active++; 974bf4ede01STejun Heo } 975bf4ede01STejun Heo 976112202d9STejun Heo static void pwq_activate_first_delayed(struct pool_workqueue *pwq) 9773aa62497SLai Jiangshan { 978112202d9STejun Heo struct work_struct *work = list_first_entry(&pwq->delayed_works, 9793aa62497SLai Jiangshan struct work_struct, entry); 9803aa62497SLai Jiangshan 981112202d9STejun Heo pwq_activate_delayed_work(work); 9823aa62497SLai Jiangshan } 9833aa62497SLai Jiangshan 984bf4ede01STejun Heo /** 985112202d9STejun Heo * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight 986112202d9STejun Heo * @pwq: pwq of interest 987bf4ede01STejun Heo * @color: color of work which left the queue 988bf4ede01STejun Heo * 989bf4ede01STejun Heo * A work either has completed or is removed from pending queue, 990112202d9STejun Heo * decrement nr_in_flight of its pwq and handle workqueue flushing. 991bf4ede01STejun Heo * 992bf4ede01STejun Heo * CONTEXT: 993d565ed63STejun Heo * spin_lock_irq(pool->lock). 994bf4ede01STejun Heo */ 995112202d9STejun Heo static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) 996bf4ede01STejun Heo { 997bf4ede01STejun Heo /* ignore uncolored works */ 998bf4ede01STejun Heo if (color == WORK_NO_COLOR) 999bf4ede01STejun Heo return; 1000bf4ede01STejun Heo 1001112202d9STejun Heo pwq->nr_in_flight[color]--; 1002bf4ede01STejun Heo 1003112202d9STejun Heo pwq->nr_active--; 1004112202d9STejun Heo if (!list_empty(&pwq->delayed_works)) { 1005bf4ede01STejun Heo /* one down, submit a delayed one */ 1006112202d9STejun Heo if (pwq->nr_active < pwq->max_active) 1007112202d9STejun Heo pwq_activate_first_delayed(pwq); 1008bf4ede01STejun Heo } 1009bf4ede01STejun Heo 1010bf4ede01STejun Heo /* is flush in progress and are we at the flushing tip? */ 1011112202d9STejun Heo if (likely(pwq->flush_color != color)) 1012bf4ede01STejun Heo return; 1013bf4ede01STejun Heo 1014bf4ede01STejun Heo /* are there still in-flight works? */ 1015112202d9STejun Heo if (pwq->nr_in_flight[color]) 1016bf4ede01STejun Heo return; 1017bf4ede01STejun Heo 1018112202d9STejun Heo /* this pwq is done, clear flush_color */ 1019112202d9STejun Heo pwq->flush_color = -1; 1020bf4ede01STejun Heo 1021bf4ede01STejun Heo /* 1022112202d9STejun Heo * If this was the last pwq, wake up the first flusher. It 1023bf4ede01STejun Heo * will handle the rest. 1024bf4ede01STejun Heo */ 1025112202d9STejun Heo if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) 1026112202d9STejun Heo complete(&pwq->wq->first_flusher->done); 1027bf4ede01STejun Heo } 1028bf4ede01STejun Heo 102936e227d2STejun Heo /** 1030bbb68dfaSTejun Heo * try_to_grab_pending - steal work item from worklist and disable irq 103136e227d2STejun Heo * @work: work item to steal 103236e227d2STejun Heo * @is_dwork: @work is a delayed_work 1033bbb68dfaSTejun Heo * @flags: place to store irq state 103436e227d2STejun Heo * 103536e227d2STejun Heo * Try to grab PENDING bit of @work. This function can handle @work in any 103636e227d2STejun Heo * stable state - idle, on timer or on worklist. Return values are 103736e227d2STejun Heo * 103836e227d2STejun Heo * 1 if @work was pending and we successfully stole PENDING 103936e227d2STejun Heo * 0 if @work was idle and we claimed PENDING 104036e227d2STejun Heo * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 1041bbb68dfaSTejun Heo * -ENOENT if someone else is canceling @work, this state may persist 1042bbb68dfaSTejun Heo * for arbitrarily long 104336e227d2STejun Heo * 1044bbb68dfaSTejun Heo * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 1045e0aecdd8STejun Heo * interrupted while holding PENDING and @work off queue, irq must be 1046e0aecdd8STejun Heo * disabled on entry. This, combined with delayed_work->timer being 1047e0aecdd8STejun Heo * irqsafe, ensures that we return -EAGAIN for finite short period of time. 1048bbb68dfaSTejun Heo * 1049bbb68dfaSTejun Heo * On successful return, >= 0, irq is disabled and the caller is 1050bbb68dfaSTejun Heo * responsible for releasing it using local_irq_restore(*@flags). 1051bbb68dfaSTejun Heo * 1052e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 1053bf4ede01STejun Heo */ 1054bbb68dfaSTejun Heo static int try_to_grab_pending(struct work_struct *work, bool is_dwork, 1055bbb68dfaSTejun Heo unsigned long *flags) 1056bf4ede01STejun Heo { 1057d565ed63STejun Heo struct worker_pool *pool; 1058112202d9STejun Heo struct pool_workqueue *pwq; 1059bf4ede01STejun Heo 1060bbb68dfaSTejun Heo local_irq_save(*flags); 1061bbb68dfaSTejun Heo 106236e227d2STejun Heo /* try to steal the timer if it exists */ 106336e227d2STejun Heo if (is_dwork) { 106436e227d2STejun Heo struct delayed_work *dwork = to_delayed_work(work); 106536e227d2STejun Heo 1066e0aecdd8STejun Heo /* 1067e0aecdd8STejun Heo * dwork->timer is irqsafe. If del_timer() fails, it's 1068e0aecdd8STejun Heo * guaranteed that the timer is not queued anywhere and not 1069e0aecdd8STejun Heo * running on the local CPU. 1070e0aecdd8STejun Heo */ 107136e227d2STejun Heo if (likely(del_timer(&dwork->timer))) 107236e227d2STejun Heo return 1; 107336e227d2STejun Heo } 107436e227d2STejun Heo 107536e227d2STejun Heo /* try to claim PENDING the normal way */ 1076bf4ede01STejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 1077bf4ede01STejun Heo return 0; 1078bf4ede01STejun Heo 1079bf4ede01STejun Heo /* 1080bf4ede01STejun Heo * The queueing is in progress, or it is already queued. Try to 1081bf4ede01STejun Heo * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 1082bf4ede01STejun Heo */ 1083d565ed63STejun Heo pool = get_work_pool(work); 1084d565ed63STejun Heo if (!pool) 1085bbb68dfaSTejun Heo goto fail; 1086bf4ede01STejun Heo 1087d565ed63STejun Heo spin_lock(&pool->lock); 1088bf4ede01STejun Heo /* 1089112202d9STejun Heo * work->data is guaranteed to point to pwq only while the work 1090112202d9STejun Heo * item is queued on pwq->wq, and both updating work->data to point 1091112202d9STejun Heo * to pwq on queueing and to pool on dequeueing are done under 1092112202d9STejun Heo * pwq->pool->lock. This in turn guarantees that, if work->data 1093112202d9STejun Heo * points to pwq which is associated with a locked pool, the work 10940b3dae68SLai Jiangshan * item is currently queued on that pool. 1095bf4ede01STejun Heo */ 1096112202d9STejun Heo pwq = get_work_pwq(work); 1097112202d9STejun Heo if (pwq && pwq->pool == pool) { 1098bf4ede01STejun Heo debug_work_deactivate(work); 10993aa62497SLai Jiangshan 11003aa62497SLai Jiangshan /* 110116062836STejun Heo * A delayed work item cannot be grabbed directly because 110216062836STejun Heo * it might have linked NO_COLOR work items which, if left 1103112202d9STejun Heo * on the delayed_list, will confuse pwq->nr_active 110416062836STejun Heo * management later on and cause stall. Make sure the work 110516062836STejun Heo * item is activated before grabbing. 11063aa62497SLai Jiangshan */ 11073aa62497SLai Jiangshan if (*work_data_bits(work) & WORK_STRUCT_DELAYED) 1108112202d9STejun Heo pwq_activate_delayed_work(work); 11093aa62497SLai Jiangshan 1110bf4ede01STejun Heo list_del_init(&work->entry); 1111112202d9STejun Heo pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work)); 111236e227d2STejun Heo 1113112202d9STejun Heo /* work->data points to pwq iff queued, point to pool */ 11144468a00fSLai Jiangshan set_work_pool_and_keep_pending(work, pool->id); 11154468a00fSLai Jiangshan 1116d565ed63STejun Heo spin_unlock(&pool->lock); 111736e227d2STejun Heo return 1; 1118bf4ede01STejun Heo } 1119d565ed63STejun Heo spin_unlock(&pool->lock); 1120bbb68dfaSTejun Heo fail: 1121bbb68dfaSTejun Heo local_irq_restore(*flags); 1122bbb68dfaSTejun Heo if (work_is_canceling(work)) 1123bbb68dfaSTejun Heo return -ENOENT; 1124bbb68dfaSTejun Heo cpu_relax(); 112536e227d2STejun Heo return -EAGAIN; 1126bf4ede01STejun Heo } 1127bf4ede01STejun Heo 1128bf4ede01STejun Heo /** 1129706026c2STejun Heo * insert_work - insert a work into a pool 1130112202d9STejun Heo * @pwq: pwq @work belongs to 11314690c4abSTejun Heo * @work: work to insert 11324690c4abSTejun Heo * @head: insertion point 11334690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 11344690c4abSTejun Heo * 1135112202d9STejun Heo * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to 1136706026c2STejun Heo * work_struct flags. 11374690c4abSTejun Heo * 11384690c4abSTejun Heo * CONTEXT: 1139d565ed63STejun Heo * spin_lock_irq(pool->lock). 1140365970a1SDavid Howells */ 1141112202d9STejun Heo static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, 1142112202d9STejun Heo struct list_head *head, unsigned int extra_flags) 1143b89deed3SOleg Nesterov { 1144112202d9STejun Heo struct worker_pool *pool = pwq->pool; 1145e1d8aa9fSFrederic Weisbecker 11464690c4abSTejun Heo /* we own @work, set data and link */ 1147112202d9STejun Heo set_work_pwq(work, pwq, extra_flags); 11481a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 1149e22bee78STejun Heo 1150e22bee78STejun Heo /* 1151e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 1152e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 1153e22bee78STejun Heo * lying around lazily while there are works to be processed. 1154e22bee78STejun Heo */ 1155e22bee78STejun Heo smp_mb(); 1156e22bee78STejun Heo 115763d95a91STejun Heo if (__need_more_worker(pool)) 115863d95a91STejun Heo wake_up_worker(pool); 1159b89deed3SOleg Nesterov } 1160b89deed3SOleg Nesterov 1161c8efcc25STejun Heo /* 1162c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 11638d03ecfeSTejun Heo * same workqueue. 1164c8efcc25STejun Heo */ 1165c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 1166c8efcc25STejun Heo { 1167c8efcc25STejun Heo struct worker *worker; 1168c8efcc25STejun Heo 11698d03ecfeSTejun Heo worker = current_wq_worker(); 1170c8efcc25STejun Heo /* 11718d03ecfeSTejun Heo * Return %true iff I'm a worker execuing a work item on @wq. If 11728d03ecfeSTejun Heo * I'm @worker, it's safe to dereference it without locking. 1173c8efcc25STejun Heo */ 1174112202d9STejun Heo return worker && worker->current_pwq->wq == wq; 1175c8efcc25STejun Heo } 1176c8efcc25STejun Heo 11774690c4abSTejun Heo static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 11781da177e4SLinus Torvalds struct work_struct *work) 11791da177e4SLinus Torvalds { 1180112202d9STejun Heo struct pool_workqueue *pwq; 11811e19ffc6STejun Heo struct list_head *worklist; 11828a2e8e5dSTejun Heo unsigned int work_flags; 1183b75cac93SJoonsoo Kim unsigned int req_cpu = cpu; 11848930cabaSTejun Heo 11858930cabaSTejun Heo /* 11868930cabaSTejun Heo * While a work item is PENDING && off queue, a task trying to 11878930cabaSTejun Heo * steal the PENDING will busy-loop waiting for it to either get 11888930cabaSTejun Heo * queued or lose PENDING. Grabbing PENDING and queueing should 11898930cabaSTejun Heo * happen with IRQ disabled. 11908930cabaSTejun Heo */ 11918930cabaSTejun Heo WARN_ON_ONCE(!irqs_disabled()); 11921da177e4SLinus Torvalds 1193dc186ad7SThomas Gleixner debug_work_activate(work); 11941e19ffc6STejun Heo 1195c8efcc25STejun Heo /* if dying, only works from the same workqueue are allowed */ 11969c5a2ba7STejun Heo if (unlikely(wq->flags & WQ_DRAINING) && 1197c8efcc25STejun Heo WARN_ON_ONCE(!is_chained_work(wq))) 1198e41e704bSTejun Heo return; 1199e41e704bSTejun Heo 1200112202d9STejun Heo /* determine the pwq to use */ 1201c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1202c9e7cf27STejun Heo struct worker_pool *last_pool; 1203c7fc77f7STejun Heo 120457469821STejun Heo if (cpu == WORK_CPU_UNBOUND) 1205f3421797STejun Heo cpu = raw_smp_processor_id(); 1206f3421797STejun Heo 120718aa9effSTejun Heo /* 1208dbf2576eSTejun Heo * It's multi cpu. If @work was previously on a different 1209dbf2576eSTejun Heo * cpu, it might still be running there, in which case the 1210dbf2576eSTejun Heo * work needs to be queued on that cpu to guarantee 1211dbf2576eSTejun Heo * non-reentrancy. 121218aa9effSTejun Heo */ 1213112202d9STejun Heo pwq = get_pwq(cpu, wq); 1214c9e7cf27STejun Heo last_pool = get_work_pool(work); 1215dbf2576eSTejun Heo 1216112202d9STejun Heo if (last_pool && last_pool != pwq->pool) { 121718aa9effSTejun Heo struct worker *worker; 121818aa9effSTejun Heo 1219d565ed63STejun Heo spin_lock(&last_pool->lock); 122018aa9effSTejun Heo 1221c9e7cf27STejun Heo worker = find_worker_executing_work(last_pool, work); 122218aa9effSTejun Heo 1223112202d9STejun Heo if (worker && worker->current_pwq->wq == wq) { 1224112202d9STejun Heo pwq = get_pwq(last_pool->cpu, wq); 12258594fadeSLai Jiangshan } else { 122618aa9effSTejun Heo /* meh... not running there, queue here */ 1227d565ed63STejun Heo spin_unlock(&last_pool->lock); 1228112202d9STejun Heo spin_lock(&pwq->pool->lock); 122918aa9effSTejun Heo } 12308930cabaSTejun Heo } else { 1231112202d9STejun Heo spin_lock(&pwq->pool->lock); 12328930cabaSTejun Heo } 1233f3421797STejun Heo } else { 1234112202d9STejun Heo pwq = get_pwq(WORK_CPU_UNBOUND, wq); 1235112202d9STejun Heo spin_lock(&pwq->pool->lock); 1236502ca9d8STejun Heo } 1237502ca9d8STejun Heo 1238112202d9STejun Heo /* pwq determined, queue */ 1239112202d9STejun Heo trace_workqueue_queue_work(req_cpu, pwq, work); 1240502ca9d8STejun Heo 1241f5b2552bSDan Carpenter if (WARN_ON(!list_empty(&work->entry))) { 1242112202d9STejun Heo spin_unlock(&pwq->pool->lock); 1243f5b2552bSDan Carpenter return; 1244f5b2552bSDan Carpenter } 12451e19ffc6STejun Heo 1246112202d9STejun Heo pwq->nr_in_flight[pwq->work_color]++; 1247112202d9STejun Heo work_flags = work_color_to_flags(pwq->work_color); 12481e19ffc6STejun Heo 1249112202d9STejun Heo if (likely(pwq->nr_active < pwq->max_active)) { 1250cdadf009STejun Heo trace_workqueue_activate_work(work); 1251112202d9STejun Heo pwq->nr_active++; 1252112202d9STejun Heo worklist = &pwq->pool->worklist; 12538a2e8e5dSTejun Heo } else { 12548a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 1255112202d9STejun Heo worklist = &pwq->delayed_works; 12568a2e8e5dSTejun Heo } 12571e19ffc6STejun Heo 1258112202d9STejun Heo insert_work(pwq, work, worklist, work_flags); 12591e19ffc6STejun Heo 1260112202d9STejun Heo spin_unlock(&pwq->pool->lock); 12611da177e4SLinus Torvalds } 12621da177e4SLinus Torvalds 12630fcb78c2SRolf Eike Beer /** 1264c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1265c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1266c1a220e7SZhang Rui * @wq: workqueue to use 1267c1a220e7SZhang Rui * @work: work to queue 1268c1a220e7SZhang Rui * 1269d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 1270c1a220e7SZhang Rui * 1271c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1272c1a220e7SZhang Rui * can't go away. 1273c1a220e7SZhang Rui */ 1274d4283e93STejun Heo bool queue_work_on(int cpu, struct workqueue_struct *wq, 1275d4283e93STejun Heo struct work_struct *work) 1276c1a220e7SZhang Rui { 1277d4283e93STejun Heo bool ret = false; 12788930cabaSTejun Heo unsigned long flags; 12798930cabaSTejun Heo 12808930cabaSTejun Heo local_irq_save(flags); 1281c1a220e7SZhang Rui 128222df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 12834690c4abSTejun Heo __queue_work(cpu, wq, work); 1284d4283e93STejun Heo ret = true; 1285c1a220e7SZhang Rui } 12868930cabaSTejun Heo 12878930cabaSTejun Heo local_irq_restore(flags); 1288c1a220e7SZhang Rui return ret; 1289c1a220e7SZhang Rui } 1290c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1291c1a220e7SZhang Rui 12920a13c00eSTejun Heo /** 12930a13c00eSTejun Heo * queue_work - queue work on a workqueue 12940a13c00eSTejun Heo * @wq: workqueue to use 12950a13c00eSTejun Heo * @work: work to queue 12960a13c00eSTejun Heo * 1297d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 12980a13c00eSTejun Heo * 12990a13c00eSTejun Heo * We queue the work to the CPU on which it was submitted, but if the CPU dies 13000a13c00eSTejun Heo * it can be processed by another CPU. 13010a13c00eSTejun Heo */ 1302d4283e93STejun Heo bool queue_work(struct workqueue_struct *wq, struct work_struct *work) 13030a13c00eSTejun Heo { 130457469821STejun Heo return queue_work_on(WORK_CPU_UNBOUND, wq, work); 13050a13c00eSTejun Heo } 13060a13c00eSTejun Heo EXPORT_SYMBOL_GPL(queue_work); 13070a13c00eSTejun Heo 1308d8e794dfSTejun Heo void delayed_work_timer_fn(unsigned long __data) 13091da177e4SLinus Torvalds { 131052bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 13111da177e4SLinus Torvalds 1312e0aecdd8STejun Heo /* should have been called from irqsafe timer with irq already off */ 131360c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 13141da177e4SLinus Torvalds } 13151438ade5SKonstantin Khlebnikov EXPORT_SYMBOL(delayed_work_timer_fn); 13161da177e4SLinus Torvalds 13177beb2edfSTejun Heo static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 131852bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 13191da177e4SLinus Torvalds { 13207beb2edfSTejun Heo struct timer_list *timer = &dwork->timer; 13217beb2edfSTejun Heo struct work_struct *work = &dwork->work; 13221da177e4SLinus Torvalds 13237beb2edfSTejun Heo WARN_ON_ONCE(timer->function != delayed_work_timer_fn || 13247beb2edfSTejun Heo timer->data != (unsigned long)dwork); 1325fc4b514fSTejun Heo WARN_ON_ONCE(timer_pending(timer)); 1326fc4b514fSTejun Heo WARN_ON_ONCE(!list_empty(&work->entry)); 13277beb2edfSTejun Heo 13288852aac2STejun Heo /* 13298852aac2STejun Heo * If @delay is 0, queue @dwork->work immediately. This is for 13308852aac2STejun Heo * both optimization and correctness. The earliest @timer can 13318852aac2STejun Heo * expire is on the closest next tick and delayed_work users depend 13328852aac2STejun Heo * on that there's no such delay when @delay is 0. 13338852aac2STejun Heo */ 13348852aac2STejun Heo if (!delay) { 13358852aac2STejun Heo __queue_work(cpu, wq, &dwork->work); 13368852aac2STejun Heo return; 13378852aac2STejun Heo } 13388852aac2STejun Heo 13397beb2edfSTejun Heo timer_stats_timer_set_start_info(&dwork->timer); 13407beb2edfSTejun Heo 134160c057bcSLai Jiangshan dwork->wq = wq; 13421265057fSTejun Heo dwork->cpu = cpu; 13437beb2edfSTejun Heo timer->expires = jiffies + delay; 13447beb2edfSTejun Heo 13457beb2edfSTejun Heo if (unlikely(cpu != WORK_CPU_UNBOUND)) 13467beb2edfSTejun Heo add_timer_on(timer, cpu); 13477beb2edfSTejun Heo else 13487beb2edfSTejun Heo add_timer(timer); 13497beb2edfSTejun Heo } 13501da177e4SLinus Torvalds 13510fcb78c2SRolf Eike Beer /** 13520fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 13530fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 13540fcb78c2SRolf Eike Beer * @wq: workqueue to use 1355af9997e4SRandy Dunlap * @dwork: work to queue 13560fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 13570fcb78c2SRolf Eike Beer * 1358715f1300STejun Heo * Returns %false if @work was already on a queue, %true otherwise. If 1359715f1300STejun Heo * @delay is zero and @dwork is idle, it will be scheduled for immediate 1360715f1300STejun Heo * execution. 13610fcb78c2SRolf Eike Beer */ 1362d4283e93STejun Heo bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 136352bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 13647a6bc1cdSVenkatesh Pallipadi { 136552bad64dSDavid Howells struct work_struct *work = &dwork->work; 1366d4283e93STejun Heo bool ret = false; 13678930cabaSTejun Heo unsigned long flags; 13688930cabaSTejun Heo 13698930cabaSTejun Heo /* read the comment in __queue_work() */ 13708930cabaSTejun Heo local_irq_save(flags); 13717a6bc1cdSVenkatesh Pallipadi 137222df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 13737beb2edfSTejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 1374d4283e93STejun Heo ret = true; 13757a6bc1cdSVenkatesh Pallipadi } 13768930cabaSTejun Heo 13778930cabaSTejun Heo local_irq_restore(flags); 13787a6bc1cdSVenkatesh Pallipadi return ret; 13797a6bc1cdSVenkatesh Pallipadi } 1380ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 13811da177e4SLinus Torvalds 1382c8e55f36STejun Heo /** 13830a13c00eSTejun Heo * queue_delayed_work - queue work on a workqueue after delay 13840a13c00eSTejun Heo * @wq: workqueue to use 13850a13c00eSTejun Heo * @dwork: delayable work to queue 13860a13c00eSTejun Heo * @delay: number of jiffies to wait before queueing 13870a13c00eSTejun Heo * 1388715f1300STejun Heo * Equivalent to queue_delayed_work_on() but tries to use the local CPU. 13890a13c00eSTejun Heo */ 1390d4283e93STejun Heo bool queue_delayed_work(struct workqueue_struct *wq, 13910a13c00eSTejun Heo struct delayed_work *dwork, unsigned long delay) 13920a13c00eSTejun Heo { 139357469821STejun Heo return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); 13940a13c00eSTejun Heo } 13950a13c00eSTejun Heo EXPORT_SYMBOL_GPL(queue_delayed_work); 13960a13c00eSTejun Heo 13970a13c00eSTejun Heo /** 13988376fe22STejun Heo * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 13998376fe22STejun Heo * @cpu: CPU number to execute work on 14008376fe22STejun Heo * @wq: workqueue to use 14018376fe22STejun Heo * @dwork: work to queue 14028376fe22STejun Heo * @delay: number of jiffies to wait before queueing 14038376fe22STejun Heo * 14048376fe22STejun Heo * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 14058376fe22STejun Heo * modify @dwork's timer so that it expires after @delay. If @delay is 14068376fe22STejun Heo * zero, @work is guaranteed to be scheduled immediately regardless of its 14078376fe22STejun Heo * current state. 14088376fe22STejun Heo * 14098376fe22STejun Heo * Returns %false if @dwork was idle and queued, %true if @dwork was 14108376fe22STejun Heo * pending and its timer was modified. 14118376fe22STejun Heo * 1412e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 14138376fe22STejun Heo * See try_to_grab_pending() for details. 14148376fe22STejun Heo */ 14158376fe22STejun Heo bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 14168376fe22STejun Heo struct delayed_work *dwork, unsigned long delay) 14178376fe22STejun Heo { 14188376fe22STejun Heo unsigned long flags; 14198376fe22STejun Heo int ret; 14208376fe22STejun Heo 14218376fe22STejun Heo do { 14228376fe22STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 14238376fe22STejun Heo } while (unlikely(ret == -EAGAIN)); 14248376fe22STejun Heo 14258376fe22STejun Heo if (likely(ret >= 0)) { 14268376fe22STejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 14278376fe22STejun Heo local_irq_restore(flags); 14288376fe22STejun Heo } 14298376fe22STejun Heo 14308376fe22STejun Heo /* -ENOENT from try_to_grab_pending() becomes %true */ 14318376fe22STejun Heo return ret; 14328376fe22STejun Heo } 14338376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work_on); 14348376fe22STejun Heo 14358376fe22STejun Heo /** 14368376fe22STejun Heo * mod_delayed_work - modify delay of or queue a delayed work 14378376fe22STejun Heo * @wq: workqueue to use 14388376fe22STejun Heo * @dwork: work to queue 14398376fe22STejun Heo * @delay: number of jiffies to wait before queueing 14408376fe22STejun Heo * 14418376fe22STejun Heo * mod_delayed_work_on() on local CPU. 14428376fe22STejun Heo */ 14438376fe22STejun Heo bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork, 14448376fe22STejun Heo unsigned long delay) 14458376fe22STejun Heo { 14468376fe22STejun Heo return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); 14478376fe22STejun Heo } 14488376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work); 14498376fe22STejun Heo 14508376fe22STejun Heo /** 1451c8e55f36STejun Heo * worker_enter_idle - enter idle state 1452c8e55f36STejun Heo * @worker: worker which is entering idle state 1453c8e55f36STejun Heo * 1454c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1455c8e55f36STejun Heo * necessary. 1456c8e55f36STejun Heo * 1457c8e55f36STejun Heo * LOCKING: 1458d565ed63STejun Heo * spin_lock_irq(pool->lock). 1459c8e55f36STejun Heo */ 1460c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 14611da177e4SLinus Torvalds { 1462bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1463c8e55f36STejun Heo 14646183c009STejun Heo if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || 14656183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->entry) && 14666183c009STejun Heo (worker->hentry.next || worker->hentry.pprev))) 14676183c009STejun Heo return; 1468c8e55f36STejun Heo 1469cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1470cb444766STejun Heo worker->flags |= WORKER_IDLE; 1471bd7bdd43STejun Heo pool->nr_idle++; 1472e22bee78STejun Heo worker->last_active = jiffies; 1473c8e55f36STejun Heo 1474c8e55f36STejun Heo /* idle_list is LIFO */ 1475bd7bdd43STejun Heo list_add(&worker->entry, &pool->idle_list); 1476db7bccf4STejun Heo 147763d95a91STejun Heo if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 1478628c78e7STejun Heo mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 1479cb444766STejun Heo 1480544ecf31STejun Heo /* 1481706026c2STejun Heo * Sanity check nr_running. Because wq_unbind_fn() releases 1482d565ed63STejun Heo * pool->lock between setting %WORKER_UNBOUND and zapping 1483628c78e7STejun Heo * nr_running, the warning may trigger spuriously. Check iff 1484628c78e7STejun Heo * unbind is not in progress. 1485544ecf31STejun Heo */ 148624647570STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 1487bd7bdd43STejun Heo pool->nr_workers == pool->nr_idle && 1488e19e397aSTejun Heo atomic_read(&pool->nr_running)); 1489c8e55f36STejun Heo } 1490c8e55f36STejun Heo 1491c8e55f36STejun Heo /** 1492c8e55f36STejun Heo * worker_leave_idle - leave idle state 1493c8e55f36STejun Heo * @worker: worker which is leaving idle state 1494c8e55f36STejun Heo * 1495c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1496c8e55f36STejun Heo * 1497c8e55f36STejun Heo * LOCKING: 1498d565ed63STejun Heo * spin_lock_irq(pool->lock). 1499c8e55f36STejun Heo */ 1500c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1501c8e55f36STejun Heo { 1502bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1503c8e55f36STejun Heo 15046183c009STejun Heo if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) 15056183c009STejun Heo return; 1506d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1507bd7bdd43STejun Heo pool->nr_idle--; 1508c8e55f36STejun Heo list_del_init(&worker->entry); 1509c8e55f36STejun Heo } 1510c8e55f36STejun Heo 1511e22bee78STejun Heo /** 1512f36dc67bSLai Jiangshan * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it 1513f36dc67bSLai Jiangshan * @pool: target worker_pool 1514f36dc67bSLai Jiangshan * 1515f36dc67bSLai Jiangshan * Bind %current to the cpu of @pool if it is associated and lock @pool. 1516e22bee78STejun Heo * 1517e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1518e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1519e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1520e22bee78STejun Heo * guaranteed to execute on the cpu. 1521e22bee78STejun Heo * 1522f5faa077SLai Jiangshan * This function is to be used by unbound workers and rescuers to bind 1523e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1524e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1525e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1526706026c2STejun Heo * verbatim as it's best effort and blocking and pool may be 1527e22bee78STejun Heo * [dis]associated in the meantime. 1528e22bee78STejun Heo * 1529706026c2STejun Heo * This function tries set_cpus_allowed() and locks pool and verifies the 153024647570STejun Heo * binding against %POOL_DISASSOCIATED which is set during 1531f2d5a0eeSTejun Heo * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker 1532f2d5a0eeSTejun Heo * enters idle state or fetches works without dropping lock, it can 1533f2d5a0eeSTejun Heo * guarantee the scheduling requirement described in the first paragraph. 1534e22bee78STejun Heo * 1535e22bee78STejun Heo * CONTEXT: 1536d565ed63STejun Heo * Might sleep. Called without any lock but returns with pool->lock 1537e22bee78STejun Heo * held. 1538e22bee78STejun Heo * 1539e22bee78STejun Heo * RETURNS: 1540706026c2STejun Heo * %true if the associated pool is online (@worker is successfully 1541e22bee78STejun Heo * bound), %false if offline. 1542e22bee78STejun Heo */ 1543f36dc67bSLai Jiangshan static bool worker_maybe_bind_and_lock(struct worker_pool *pool) 1544d565ed63STejun Heo __acquires(&pool->lock) 1545e22bee78STejun Heo { 1546e22bee78STejun Heo while (true) { 1547e22bee78STejun Heo /* 1548e22bee78STejun Heo * The following call may fail, succeed or succeed 1549e22bee78STejun Heo * without actually migrating the task to the cpu if 1550e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 155124647570STejun Heo * against POOL_DISASSOCIATED. 1552e22bee78STejun Heo */ 155324647570STejun Heo if (!(pool->flags & POOL_DISASSOCIATED)) 1554f5faa077SLai Jiangshan set_cpus_allowed_ptr(current, get_cpu_mask(pool->cpu)); 1555e22bee78STejun Heo 1556d565ed63STejun Heo spin_lock_irq(&pool->lock); 155724647570STejun Heo if (pool->flags & POOL_DISASSOCIATED) 1558e22bee78STejun Heo return false; 1559f5faa077SLai Jiangshan if (task_cpu(current) == pool->cpu && 1560e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1561ec22ca5eSTejun Heo get_cpu_mask(pool->cpu))) 1562e22bee78STejun Heo return true; 1563d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1564e22bee78STejun Heo 15655035b20fSTejun Heo /* 15665035b20fSTejun Heo * We've raced with CPU hot[un]plug. Give it a breather 15675035b20fSTejun Heo * and retry migration. cond_resched() is required here; 15685035b20fSTejun Heo * otherwise, we might deadlock against cpu_stop trying to 15695035b20fSTejun Heo * bring down the CPU on non-preemptive kernel. 15705035b20fSTejun Heo */ 1571e22bee78STejun Heo cpu_relax(); 15725035b20fSTejun Heo cond_resched(); 1573e22bee78STejun Heo } 1574e22bee78STejun Heo } 1575e22bee78STejun Heo 1576e22bee78STejun Heo /* 1577ea1abd61SLai Jiangshan * Rebind an idle @worker to its CPU. worker_thread() will test 15785f7dabfdSLai Jiangshan * list_empty(@worker->entry) before leaving idle and call this function. 157925511a47STejun Heo */ 158025511a47STejun Heo static void idle_worker_rebind(struct worker *worker) 158125511a47STejun Heo { 15825f7dabfdSLai Jiangshan /* CPU may go down again inbetween, clear UNBOUND only on success */ 1583f36dc67bSLai Jiangshan if (worker_maybe_bind_and_lock(worker->pool)) 15845f7dabfdSLai Jiangshan worker_clr_flags(worker, WORKER_UNBOUND); 158525511a47STejun Heo 1586ea1abd61SLai Jiangshan /* rebind complete, become available again */ 1587ea1abd61SLai Jiangshan list_add(&worker->entry, &worker->pool->idle_list); 1588d565ed63STejun Heo spin_unlock_irq(&worker->pool->lock); 158925511a47STejun Heo } 159025511a47STejun Heo 159125511a47STejun Heo /* 159225511a47STejun Heo * Function for @worker->rebind.work used to rebind unbound busy workers to 1593403c821dSTejun Heo * the associated cpu which is coming back online. This is scheduled by 1594403c821dSTejun Heo * cpu up but can race with other cpu hotplug operations and may be 1595403c821dSTejun Heo * executed twice without intervening cpu down. 1596e22bee78STejun Heo */ 159725511a47STejun Heo static void busy_worker_rebind_fn(struct work_struct *work) 1598e22bee78STejun Heo { 1599e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1600e22bee78STejun Heo 1601f36dc67bSLai Jiangshan if (worker_maybe_bind_and_lock(worker->pool)) 1602eab6d828SLai Jiangshan worker_clr_flags(worker, WORKER_UNBOUND); 1603e22bee78STejun Heo 1604d565ed63STejun Heo spin_unlock_irq(&worker->pool->lock); 1605e22bee78STejun Heo } 1606e22bee78STejun Heo 160725511a47STejun Heo /** 160894cf58bbSTejun Heo * rebind_workers - rebind all workers of a pool to the associated CPU 160994cf58bbSTejun Heo * @pool: pool of interest 161025511a47STejun Heo * 161194cf58bbSTejun Heo * @pool->cpu is coming online. Rebind all workers to the CPU. Rebinding 161225511a47STejun Heo * is different for idle and busy ones. 161325511a47STejun Heo * 1614ea1abd61SLai Jiangshan * Idle ones will be removed from the idle_list and woken up. They will 1615ea1abd61SLai Jiangshan * add themselves back after completing rebind. This ensures that the 1616ea1abd61SLai Jiangshan * idle_list doesn't contain any unbound workers when re-bound busy workers 1617ea1abd61SLai Jiangshan * try to perform local wake-ups for concurrency management. 161825511a47STejun Heo * 1619ea1abd61SLai Jiangshan * Busy workers can rebind after they finish their current work items. 1620ea1abd61SLai Jiangshan * Queueing the rebind work item at the head of the scheduled list is 1621ea1abd61SLai Jiangshan * enough. Note that nr_running will be properly bumped as busy workers 1622ea1abd61SLai Jiangshan * rebind. 162325511a47STejun Heo * 1624ea1abd61SLai Jiangshan * On return, all non-manager workers are scheduled for rebind - see 1625ea1abd61SLai Jiangshan * manage_workers() for the manager special case. Any idle worker 1626ea1abd61SLai Jiangshan * including the manager will not appear on @idle_list until rebind is 1627ea1abd61SLai Jiangshan * complete, making local wake-ups safe. 162825511a47STejun Heo */ 162994cf58bbSTejun Heo static void rebind_workers(struct worker_pool *pool) 163025511a47STejun Heo { 1631ea1abd61SLai Jiangshan struct worker *worker, *n; 163225511a47STejun Heo int i; 163325511a47STejun Heo 1634b2eb83d1SLai Jiangshan lockdep_assert_held(&pool->assoc_mutex); 1635d565ed63STejun Heo lockdep_assert_held(&pool->lock); 163625511a47STejun Heo 16375f7dabfdSLai Jiangshan /* dequeue and kick idle ones */ 1638ea1abd61SLai Jiangshan list_for_each_entry_safe(worker, n, &pool->idle_list, entry) { 1639ea1abd61SLai Jiangshan /* 164094cf58bbSTejun Heo * idle workers should be off @pool->idle_list until rebind 164194cf58bbSTejun Heo * is complete to avoid receiving premature local wake-ups. 1642ea1abd61SLai Jiangshan */ 1643ea1abd61SLai Jiangshan list_del_init(&worker->entry); 164425511a47STejun Heo 164525511a47STejun Heo /* 164694cf58bbSTejun Heo * worker_thread() will see the above dequeuing and call 164794cf58bbSTejun Heo * idle_worker_rebind(). 164825511a47STejun Heo */ 164925511a47STejun Heo wake_up_process(worker->task); 165025511a47STejun Heo } 165125511a47STejun Heo 1652ea1abd61SLai Jiangshan /* rebind busy workers */ 1653b67bfe0dSSasha Levin for_each_busy_worker(worker, i, pool) { 165425511a47STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 1655e2b6a6d5SJoonsoo Kim struct workqueue_struct *wq; 165625511a47STejun Heo 165725511a47STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 165825511a47STejun Heo work_data_bits(rebind_work))) 165925511a47STejun Heo continue; 166025511a47STejun Heo 166125511a47STejun Heo debug_work_activate(rebind_work); 166290beca5dSTejun Heo 166390beca5dSTejun Heo /* 166494cf58bbSTejun Heo * wq doesn't really matter but let's keep @worker->pool 1665112202d9STejun Heo * and @pwq->pool consistent for sanity. 166690beca5dSTejun Heo */ 1667e34cdddbSTejun Heo if (std_worker_pool_pri(worker->pool)) 1668e2b6a6d5SJoonsoo Kim wq = system_highpri_wq; 1669e2b6a6d5SJoonsoo Kim else 1670e2b6a6d5SJoonsoo Kim wq = system_wq; 1671ec58815aSTejun Heo 1672112202d9STejun Heo insert_work(get_pwq(pool->cpu, wq), rebind_work, 167325511a47STejun Heo worker->scheduled.next, 167425511a47STejun Heo work_color_to_flags(WORK_NO_COLOR)); 1675ec58815aSTejun Heo } 167625511a47STejun Heo } 167725511a47STejun Heo 1678c34056a3STejun Heo static struct worker *alloc_worker(void) 1679c34056a3STejun Heo { 1680c34056a3STejun Heo struct worker *worker; 1681c34056a3STejun Heo 1682c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1683c8e55f36STejun Heo if (worker) { 1684c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1685affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 168625511a47STejun Heo INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn); 1687e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1688e22bee78STejun Heo worker->flags = WORKER_PREP; 1689c8e55f36STejun Heo } 1690c34056a3STejun Heo return worker; 1691c34056a3STejun Heo } 1692c34056a3STejun Heo 1693c34056a3STejun Heo /** 1694c34056a3STejun Heo * create_worker - create a new workqueue worker 169563d95a91STejun Heo * @pool: pool the new worker will belong to 1696c34056a3STejun Heo * 169763d95a91STejun Heo * Create a new worker which is bound to @pool. The returned worker 1698c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1699c34056a3STejun Heo * destroy_worker(). 1700c34056a3STejun Heo * 1701c34056a3STejun Heo * CONTEXT: 1702c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1703c34056a3STejun Heo * 1704c34056a3STejun Heo * RETURNS: 1705c34056a3STejun Heo * Pointer to the newly created worker. 1706c34056a3STejun Heo */ 1707bc2ae0f5STejun Heo static struct worker *create_worker(struct worker_pool *pool) 1708c34056a3STejun Heo { 1709e34cdddbSTejun Heo const char *pri = std_worker_pool_pri(pool) ? "H" : ""; 1710c34056a3STejun Heo struct worker *worker = NULL; 1711f3421797STejun Heo int id = -1; 1712c34056a3STejun Heo 1713d565ed63STejun Heo spin_lock_irq(&pool->lock); 1714bd7bdd43STejun Heo while (ida_get_new(&pool->worker_ida, &id)) { 1715d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1716bd7bdd43STejun Heo if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL)) 1717c34056a3STejun Heo goto fail; 1718d565ed63STejun Heo spin_lock_irq(&pool->lock); 1719c34056a3STejun Heo } 1720d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1721c34056a3STejun Heo 1722c34056a3STejun Heo worker = alloc_worker(); 1723c34056a3STejun Heo if (!worker) 1724c34056a3STejun Heo goto fail; 1725c34056a3STejun Heo 1726bd7bdd43STejun Heo worker->pool = pool; 1727c34056a3STejun Heo worker->id = id; 1728c34056a3STejun Heo 1729ec22ca5eSTejun Heo if (pool->cpu != WORK_CPU_UNBOUND) 173094dcf29aSEric Dumazet worker->task = kthread_create_on_node(worker_thread, 1731ec22ca5eSTejun Heo worker, cpu_to_node(pool->cpu), 1732ec22ca5eSTejun Heo "kworker/%u:%d%s", pool->cpu, id, pri); 1733f3421797STejun Heo else 1734f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 17353270476aSTejun Heo "kworker/u:%d%s", id, pri); 1736c34056a3STejun Heo if (IS_ERR(worker->task)) 1737c34056a3STejun Heo goto fail; 1738c34056a3STejun Heo 1739e34cdddbSTejun Heo if (std_worker_pool_pri(pool)) 17403270476aSTejun Heo set_user_nice(worker->task, HIGHPRI_NICE_LEVEL); 17413270476aSTejun Heo 1742db7bccf4STejun Heo /* 1743bc2ae0f5STejun Heo * Determine CPU binding of the new worker depending on 174424647570STejun Heo * %POOL_DISASSOCIATED. The caller is responsible for ensuring the 1745bc2ae0f5STejun Heo * flag remains stable across this function. See the comments 1746bc2ae0f5STejun Heo * above the flag definition for details. 1747bc2ae0f5STejun Heo * 1748bc2ae0f5STejun Heo * As an unbound worker may later become a regular one if CPU comes 1749bc2ae0f5STejun Heo * online, make sure every worker has %PF_THREAD_BOUND set. 1750db7bccf4STejun Heo */ 175124647570STejun Heo if (!(pool->flags & POOL_DISASSOCIATED)) { 1752ec22ca5eSTejun Heo kthread_bind(worker->task, pool->cpu); 1753bc2ae0f5STejun Heo } else { 1754db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1755f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1756f3421797STejun Heo } 1757c34056a3STejun Heo 1758c34056a3STejun Heo return worker; 1759c34056a3STejun Heo fail: 1760c34056a3STejun Heo if (id >= 0) { 1761d565ed63STejun Heo spin_lock_irq(&pool->lock); 1762bd7bdd43STejun Heo ida_remove(&pool->worker_ida, id); 1763d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1764c34056a3STejun Heo } 1765c34056a3STejun Heo kfree(worker); 1766c34056a3STejun Heo return NULL; 1767c34056a3STejun Heo } 1768c34056a3STejun Heo 1769c34056a3STejun Heo /** 1770c34056a3STejun Heo * start_worker - start a newly created worker 1771c34056a3STejun Heo * @worker: worker to start 1772c34056a3STejun Heo * 1773706026c2STejun Heo * Make the pool aware of @worker and start it. 1774c34056a3STejun Heo * 1775c34056a3STejun Heo * CONTEXT: 1776d565ed63STejun Heo * spin_lock_irq(pool->lock). 1777c34056a3STejun Heo */ 1778c34056a3STejun Heo static void start_worker(struct worker *worker) 1779c34056a3STejun Heo { 1780cb444766STejun Heo worker->flags |= WORKER_STARTED; 1781bd7bdd43STejun Heo worker->pool->nr_workers++; 1782c8e55f36STejun Heo worker_enter_idle(worker); 1783c34056a3STejun Heo wake_up_process(worker->task); 1784c34056a3STejun Heo } 1785c34056a3STejun Heo 1786c34056a3STejun Heo /** 1787c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1788c34056a3STejun Heo * @worker: worker to be destroyed 1789c34056a3STejun Heo * 1790706026c2STejun Heo * Destroy @worker and adjust @pool stats accordingly. 1791c8e55f36STejun Heo * 1792c8e55f36STejun Heo * CONTEXT: 1793d565ed63STejun Heo * spin_lock_irq(pool->lock) which is released and regrabbed. 1794c34056a3STejun Heo */ 1795c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1796c34056a3STejun Heo { 1797bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1798c34056a3STejun Heo int id = worker->id; 1799c34056a3STejun Heo 1800c34056a3STejun Heo /* sanity check frenzy */ 18016183c009STejun Heo if (WARN_ON(worker->current_work) || 18026183c009STejun Heo WARN_ON(!list_empty(&worker->scheduled))) 18036183c009STejun Heo return; 1804c34056a3STejun Heo 1805c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1806bd7bdd43STejun Heo pool->nr_workers--; 1807c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1808bd7bdd43STejun Heo pool->nr_idle--; 1809c8e55f36STejun Heo 1810c8e55f36STejun Heo list_del_init(&worker->entry); 1811cb444766STejun Heo worker->flags |= WORKER_DIE; 1812c8e55f36STejun Heo 1813d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1814c8e55f36STejun Heo 1815c34056a3STejun Heo kthread_stop(worker->task); 1816c34056a3STejun Heo kfree(worker); 1817c34056a3STejun Heo 1818d565ed63STejun Heo spin_lock_irq(&pool->lock); 1819bd7bdd43STejun Heo ida_remove(&pool->worker_ida, id); 1820c34056a3STejun Heo } 1821c34056a3STejun Heo 182263d95a91STejun Heo static void idle_worker_timeout(unsigned long __pool) 1823e22bee78STejun Heo { 182463d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 1825e22bee78STejun Heo 1826d565ed63STejun Heo spin_lock_irq(&pool->lock); 1827e22bee78STejun Heo 182863d95a91STejun Heo if (too_many_workers(pool)) { 1829e22bee78STejun Heo struct worker *worker; 1830e22bee78STejun Heo unsigned long expires; 1831e22bee78STejun Heo 1832e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 183363d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 1834e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1835e22bee78STejun Heo 1836e22bee78STejun Heo if (time_before(jiffies, expires)) 183763d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 1838e22bee78STejun Heo else { 1839e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 184011ebea50STejun Heo pool->flags |= POOL_MANAGE_WORKERS; 184163d95a91STejun Heo wake_up_worker(pool); 1842e22bee78STejun Heo } 1843e22bee78STejun Heo } 1844e22bee78STejun Heo 1845d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1846e22bee78STejun Heo } 1847e22bee78STejun Heo 1848e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1849e22bee78STejun Heo { 1850112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 1851112202d9STejun Heo struct workqueue_struct *wq = pwq->wq; 1852f3421797STejun Heo unsigned int cpu; 1853e22bee78STejun Heo 1854e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1855e22bee78STejun Heo return false; 1856e22bee78STejun Heo 1857e22bee78STejun Heo /* mayday mayday mayday */ 1858112202d9STejun Heo cpu = pwq->pool->cpu; 1859f3421797STejun Heo /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1860f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 1861f3421797STejun Heo cpu = 0; 1862f2e005aaSTejun Heo if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) 1863e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1864e22bee78STejun Heo return true; 1865e22bee78STejun Heo } 1866e22bee78STejun Heo 1867706026c2STejun Heo static void pool_mayday_timeout(unsigned long __pool) 1868e22bee78STejun Heo { 186963d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 1870e22bee78STejun Heo struct work_struct *work; 1871e22bee78STejun Heo 1872d565ed63STejun Heo spin_lock_irq(&pool->lock); 1873e22bee78STejun Heo 187463d95a91STejun Heo if (need_to_create_worker(pool)) { 1875e22bee78STejun Heo /* 1876e22bee78STejun Heo * We've been trying to create a new worker but 1877e22bee78STejun Heo * haven't been successful. We might be hitting an 1878e22bee78STejun Heo * allocation deadlock. Send distress signals to 1879e22bee78STejun Heo * rescuers. 1880e22bee78STejun Heo */ 188163d95a91STejun Heo list_for_each_entry(work, &pool->worklist, entry) 1882e22bee78STejun Heo send_mayday(work); 1883e22bee78STejun Heo } 1884e22bee78STejun Heo 1885d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1886e22bee78STejun Heo 188763d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 1888e22bee78STejun Heo } 1889e22bee78STejun Heo 1890e22bee78STejun Heo /** 1891e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 189263d95a91STejun Heo * @pool: pool to create a new worker for 1893e22bee78STejun Heo * 189463d95a91STejun Heo * Create a new worker for @pool if necessary. @pool is guaranteed to 1895e22bee78STejun Heo * have at least one idle worker on return from this function. If 1896e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 189763d95a91STejun Heo * sent to all rescuers with works scheduled on @pool to resolve 1898e22bee78STejun Heo * possible allocation deadlock. 1899e22bee78STejun Heo * 1900e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1901e22bee78STejun Heo * may_start_working() true. 1902e22bee78STejun Heo * 1903e22bee78STejun Heo * LOCKING: 1904d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 1905e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1906e22bee78STejun Heo * manager. 1907e22bee78STejun Heo * 1908e22bee78STejun Heo * RETURNS: 1909d565ed63STejun Heo * false if no action was taken and pool->lock stayed locked, true 1910e22bee78STejun Heo * otherwise. 1911e22bee78STejun Heo */ 191263d95a91STejun Heo static bool maybe_create_worker(struct worker_pool *pool) 1913d565ed63STejun Heo __releases(&pool->lock) 1914d565ed63STejun Heo __acquires(&pool->lock) 1915e22bee78STejun Heo { 191663d95a91STejun Heo if (!need_to_create_worker(pool)) 1917e22bee78STejun Heo return false; 1918e22bee78STejun Heo restart: 1919d565ed63STejun Heo spin_unlock_irq(&pool->lock); 19209f9c2364STejun Heo 1921e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 192263d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1923e22bee78STejun Heo 1924e22bee78STejun Heo while (true) { 1925e22bee78STejun Heo struct worker *worker; 1926e22bee78STejun Heo 1927bc2ae0f5STejun Heo worker = create_worker(pool); 1928e22bee78STejun Heo if (worker) { 192963d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 1930d565ed63STejun Heo spin_lock_irq(&pool->lock); 1931e22bee78STejun Heo start_worker(worker); 19326183c009STejun Heo if (WARN_ON_ONCE(need_to_create_worker(pool))) 19336183c009STejun Heo goto restart; 1934e22bee78STejun Heo return true; 1935e22bee78STejun Heo } 1936e22bee78STejun Heo 193763d95a91STejun Heo if (!need_to_create_worker(pool)) 1938e22bee78STejun Heo break; 1939e22bee78STejun Heo 1940e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1941e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 19429f9c2364STejun Heo 194363d95a91STejun Heo if (!need_to_create_worker(pool)) 1944e22bee78STejun Heo break; 1945e22bee78STejun Heo } 1946e22bee78STejun Heo 194763d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 1948d565ed63STejun Heo spin_lock_irq(&pool->lock); 194963d95a91STejun Heo if (need_to_create_worker(pool)) 1950e22bee78STejun Heo goto restart; 1951e22bee78STejun Heo return true; 1952e22bee78STejun Heo } 1953e22bee78STejun Heo 1954e22bee78STejun Heo /** 1955e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 195663d95a91STejun Heo * @pool: pool to destroy workers for 1957e22bee78STejun Heo * 195863d95a91STejun Heo * Destroy @pool workers which have been idle for longer than 1959e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1960e22bee78STejun Heo * 1961e22bee78STejun Heo * LOCKING: 1962d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 1963e22bee78STejun Heo * multiple times. Called only from manager. 1964e22bee78STejun Heo * 1965e22bee78STejun Heo * RETURNS: 1966d565ed63STejun Heo * false if no action was taken and pool->lock stayed locked, true 1967e22bee78STejun Heo * otherwise. 1968e22bee78STejun Heo */ 196963d95a91STejun Heo static bool maybe_destroy_workers(struct worker_pool *pool) 1970e22bee78STejun Heo { 1971e22bee78STejun Heo bool ret = false; 1972e22bee78STejun Heo 197363d95a91STejun Heo while (too_many_workers(pool)) { 1974e22bee78STejun Heo struct worker *worker; 1975e22bee78STejun Heo unsigned long expires; 1976e22bee78STejun Heo 197763d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 1978e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1979e22bee78STejun Heo 1980e22bee78STejun Heo if (time_before(jiffies, expires)) { 198163d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 1982e22bee78STejun Heo break; 1983e22bee78STejun Heo } 1984e22bee78STejun Heo 1985e22bee78STejun Heo destroy_worker(worker); 1986e22bee78STejun Heo ret = true; 1987e22bee78STejun Heo } 1988e22bee78STejun Heo 1989e22bee78STejun Heo return ret; 1990e22bee78STejun Heo } 1991e22bee78STejun Heo 1992e22bee78STejun Heo /** 1993e22bee78STejun Heo * manage_workers - manage worker pool 1994e22bee78STejun Heo * @worker: self 1995e22bee78STejun Heo * 1996706026c2STejun Heo * Assume the manager role and manage the worker pool @worker belongs 1997e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 1998706026c2STejun Heo * pool. The exclusion is handled automatically by this function. 1999e22bee78STejun Heo * 2000e22bee78STejun Heo * The caller can safely start processing works on false return. On 2001e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 2002e22bee78STejun Heo * and may_start_working() is true. 2003e22bee78STejun Heo * 2004e22bee78STejun Heo * CONTEXT: 2005d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2006e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 2007e22bee78STejun Heo * 2008e22bee78STejun Heo * RETURNS: 2009d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2010d565ed63STejun Heo * multiple times. Does GFP_KERNEL allocations. 2011e22bee78STejun Heo */ 2012e22bee78STejun Heo static bool manage_workers(struct worker *worker) 2013e22bee78STejun Heo { 201463d95a91STejun Heo struct worker_pool *pool = worker->pool; 2015e22bee78STejun Heo bool ret = false; 2016e22bee78STejun Heo 2017ee378aa4SLai Jiangshan if (pool->flags & POOL_MANAGING_WORKERS) 2018e22bee78STejun Heo return ret; 2019e22bee78STejun Heo 2020552a37e9SLai Jiangshan pool->flags |= POOL_MANAGING_WORKERS; 2021ee378aa4SLai Jiangshan 2022ee378aa4SLai Jiangshan /* 2023ee378aa4SLai Jiangshan * To simplify both worker management and CPU hotplug, hold off 2024ee378aa4SLai Jiangshan * management while hotplug is in progress. CPU hotplug path can't 2025ee378aa4SLai Jiangshan * grab %POOL_MANAGING_WORKERS to achieve this because that can 2026ee378aa4SLai Jiangshan * lead to idle worker depletion (all become busy thinking someone 2027ee378aa4SLai Jiangshan * else is managing) which in turn can result in deadlock under 2028b2eb83d1SLai Jiangshan * extreme circumstances. Use @pool->assoc_mutex to synchronize 2029ee378aa4SLai Jiangshan * manager against CPU hotplug. 2030ee378aa4SLai Jiangshan * 2031b2eb83d1SLai Jiangshan * assoc_mutex would always be free unless CPU hotplug is in 2032d565ed63STejun Heo * progress. trylock first without dropping @pool->lock. 2033ee378aa4SLai Jiangshan */ 2034b2eb83d1SLai Jiangshan if (unlikely(!mutex_trylock(&pool->assoc_mutex))) { 2035d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2036b2eb83d1SLai Jiangshan mutex_lock(&pool->assoc_mutex); 2037ee378aa4SLai Jiangshan /* 2038ee378aa4SLai Jiangshan * CPU hotplug could have happened while we were waiting 2039b2eb83d1SLai Jiangshan * for assoc_mutex. Hotplug itself can't handle us 2040ee378aa4SLai Jiangshan * because manager isn't either on idle or busy list, and 2041706026c2STejun Heo * @pool's state and ours could have deviated. 2042ee378aa4SLai Jiangshan * 2043b2eb83d1SLai Jiangshan * As hotplug is now excluded via assoc_mutex, we can 2044ee378aa4SLai Jiangshan * simply try to bind. It will succeed or fail depending 2045706026c2STejun Heo * on @pool's current state. Try it and adjust 2046ee378aa4SLai Jiangshan * %WORKER_UNBOUND accordingly. 2047ee378aa4SLai Jiangshan */ 2048f36dc67bSLai Jiangshan if (worker_maybe_bind_and_lock(pool)) 2049ee378aa4SLai Jiangshan worker->flags &= ~WORKER_UNBOUND; 2050ee378aa4SLai Jiangshan else 2051ee378aa4SLai Jiangshan worker->flags |= WORKER_UNBOUND; 2052ee378aa4SLai Jiangshan 2053ee378aa4SLai Jiangshan ret = true; 2054ee378aa4SLai Jiangshan } 2055ee378aa4SLai Jiangshan 205611ebea50STejun Heo pool->flags &= ~POOL_MANAGE_WORKERS; 2057e22bee78STejun Heo 2058e22bee78STejun Heo /* 2059e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 2060e22bee78STejun Heo * on return. 2061e22bee78STejun Heo */ 206263d95a91STejun Heo ret |= maybe_destroy_workers(pool); 206363d95a91STejun Heo ret |= maybe_create_worker(pool); 2064e22bee78STejun Heo 2065552a37e9SLai Jiangshan pool->flags &= ~POOL_MANAGING_WORKERS; 2066b2eb83d1SLai Jiangshan mutex_unlock(&pool->assoc_mutex); 2067e22bee78STejun Heo return ret; 2068e22bee78STejun Heo } 2069e22bee78STejun Heo 2070a62428c0STejun Heo /** 2071a62428c0STejun Heo * process_one_work - process single work 2072c34056a3STejun Heo * @worker: self 2073a62428c0STejun Heo * @work: work to process 2074a62428c0STejun Heo * 2075a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 2076a62428c0STejun Heo * process a single work including synchronization against and 2077a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 2078a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 2079a62428c0STejun Heo * call this function to process a work. 2080a62428c0STejun Heo * 2081a62428c0STejun Heo * CONTEXT: 2082d565ed63STejun Heo * spin_lock_irq(pool->lock) which is released and regrabbed. 2083a62428c0STejun Heo */ 2084c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 2085d565ed63STejun Heo __releases(&pool->lock) 2086d565ed63STejun Heo __acquires(&pool->lock) 20871da177e4SLinus Torvalds { 2088112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2089bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2090112202d9STejun Heo bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; 209173f53c4aSTejun Heo int work_color; 20927e11629dSTejun Heo struct worker *collision; 20934e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 20944e6045f1SJohannes Berg /* 2095a62428c0STejun Heo * It is permissible to free the struct work_struct from 2096a62428c0STejun Heo * inside the function that is called from it, this we need to 2097a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 2098a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 2099a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 21004e6045f1SJohannes Berg */ 21014d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 21024d82a1deSPeter Zijlstra 21034d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 21044e6045f1SJohannes Berg #endif 21056fec10a1STejun Heo /* 21066fec10a1STejun Heo * Ensure we're on the correct CPU. DISASSOCIATED test is 21076fec10a1STejun Heo * necessary to avoid spurious warnings from rescuers servicing the 210824647570STejun Heo * unbound or a disassociated pool. 21096fec10a1STejun Heo */ 21105f7dabfdSLai Jiangshan WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && 211124647570STejun Heo !(pool->flags & POOL_DISASSOCIATED) && 2112ec22ca5eSTejun Heo raw_smp_processor_id() != pool->cpu); 211325511a47STejun Heo 21147e11629dSTejun Heo /* 21157e11629dSTejun Heo * A single work shouldn't be executed concurrently by 21167e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 21177e11629dSTejun Heo * already processing the work. If so, defer the work to the 21187e11629dSTejun Heo * currently executing one. 21197e11629dSTejun Heo */ 2120c9e7cf27STejun Heo collision = find_worker_executing_work(pool, work); 21217e11629dSTejun Heo if (unlikely(collision)) { 21227e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 21237e11629dSTejun Heo return; 21247e11629dSTejun Heo } 21251da177e4SLinus Torvalds 21268930cabaSTejun Heo /* claim and dequeue */ 21271da177e4SLinus Torvalds debug_work_deactivate(work); 2128c9e7cf27STejun Heo hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); 2129c34056a3STejun Heo worker->current_work = work; 2130a2c1c57bSTejun Heo worker->current_func = work->func; 2131112202d9STejun Heo worker->current_pwq = pwq; 213273f53c4aSTejun Heo work_color = get_work_color(work); 21337a22ad75STejun Heo 2134a62428c0STejun Heo list_del_init(&work->entry); 2135a62428c0STejun Heo 2136649027d7STejun Heo /* 2137fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 2138fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 2139fb0e7bebSTejun Heo */ 2140fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2141fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 2142fb0e7bebSTejun Heo 2143974271c4STejun Heo /* 2144d565ed63STejun Heo * Unbound pool isn't concurrency managed and work items should be 2145974271c4STejun Heo * executed ASAP. Wake up another worker if necessary. 2146974271c4STejun Heo */ 214763d95a91STejun Heo if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) 214863d95a91STejun Heo wake_up_worker(pool); 2149974271c4STejun Heo 21508930cabaSTejun Heo /* 21517c3eed5cSTejun Heo * Record the last pool and clear PENDING which should be the last 2152d565ed63STejun Heo * update to @work. Also, do this inside @pool->lock so that 215323657bb1STejun Heo * PENDING and queued state changes happen together while IRQ is 215423657bb1STejun Heo * disabled. 21558930cabaSTejun Heo */ 21567c3eed5cSTejun Heo set_work_pool_and_clear_pending(work, pool->id); 21571da177e4SLinus Torvalds 2158d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2159365970a1SDavid Howells 2160112202d9STejun Heo lock_map_acquire_read(&pwq->wq->lockdep_map); 21613295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 2162e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 2163a2c1c57bSTejun Heo worker->current_func(work); 2164e36c886aSArjan van de Ven /* 2165e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 2166e36c886aSArjan van de Ven * point will only record its address. 2167e36c886aSArjan van de Ven */ 2168e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 21693295f0efSIngo Molnar lock_map_release(&lockdep_map); 2170112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 21711da177e4SLinus Torvalds 2172d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 2173044c782cSValentin Ilie pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" 2174044c782cSValentin Ilie " last function: %pf\n", 2175a2c1c57bSTejun Heo current->comm, preempt_count(), task_pid_nr(current), 2176a2c1c57bSTejun Heo worker->current_func); 2177d5abe669SPeter Zijlstra debug_show_held_locks(current); 2178d5abe669SPeter Zijlstra dump_stack(); 2179d5abe669SPeter Zijlstra } 2180d5abe669SPeter Zijlstra 2181d565ed63STejun Heo spin_lock_irq(&pool->lock); 2182a62428c0STejun Heo 2183fb0e7bebSTejun Heo /* clear cpu intensive status */ 2184fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2185fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 2186fb0e7bebSTejun Heo 2187a62428c0STejun Heo /* we're done with it, release */ 218842f8570fSSasha Levin hash_del(&worker->hentry); 2189c34056a3STejun Heo worker->current_work = NULL; 2190a2c1c57bSTejun Heo worker->current_func = NULL; 2191112202d9STejun Heo worker->current_pwq = NULL; 2192112202d9STejun Heo pwq_dec_nr_in_flight(pwq, work_color); 21931da177e4SLinus Torvalds } 21941da177e4SLinus Torvalds 2195affee4b2STejun Heo /** 2196affee4b2STejun Heo * process_scheduled_works - process scheduled works 2197affee4b2STejun Heo * @worker: self 2198affee4b2STejun Heo * 2199affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 2200affee4b2STejun Heo * may change while processing a work, so this function repeatedly 2201affee4b2STejun Heo * fetches a work from the top and executes it. 2202affee4b2STejun Heo * 2203affee4b2STejun Heo * CONTEXT: 2204d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2205affee4b2STejun Heo * multiple times. 2206affee4b2STejun Heo */ 2207affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 22081da177e4SLinus Torvalds { 2209affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 2210affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 2211a62428c0STejun Heo struct work_struct, entry); 2212c34056a3STejun Heo process_one_work(worker, work); 2213a62428c0STejun Heo } 22141da177e4SLinus Torvalds } 22151da177e4SLinus Torvalds 22164690c4abSTejun Heo /** 22174690c4abSTejun Heo * worker_thread - the worker thread function 2218c34056a3STejun Heo * @__worker: self 22194690c4abSTejun Heo * 2220706026c2STejun Heo * The worker thread function. There are NR_CPU_WORKER_POOLS dynamic pools 2221706026c2STejun Heo * of these per each cpu. These workers process all works regardless of 2222e22bee78STejun Heo * their specific target workqueue. The only exception is works which 2223e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 2224e22bee78STejun Heo * rescuer_thread(). 22254690c4abSTejun Heo */ 2226c34056a3STejun Heo static int worker_thread(void *__worker) 22271da177e4SLinus Torvalds { 2228c34056a3STejun Heo struct worker *worker = __worker; 2229bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 22301da177e4SLinus Torvalds 2231e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 2232e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 2233c8e55f36STejun Heo woke_up: 2234d565ed63STejun Heo spin_lock_irq(&pool->lock); 2235affee4b2STejun Heo 22365f7dabfdSLai Jiangshan /* we are off idle list if destruction or rebind is requested */ 22375f7dabfdSLai Jiangshan if (unlikely(list_empty(&worker->entry))) { 2238d565ed63STejun Heo spin_unlock_irq(&pool->lock); 223925511a47STejun Heo 22405f7dabfdSLai Jiangshan /* if DIE is set, destruction is requested */ 224125511a47STejun Heo if (worker->flags & WORKER_DIE) { 2242e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 2243c8e55f36STejun Heo return 0; 2244c8e55f36STejun Heo } 2245c8e55f36STejun Heo 22465f7dabfdSLai Jiangshan /* otherwise, rebind */ 224725511a47STejun Heo idle_worker_rebind(worker); 224825511a47STejun Heo goto woke_up; 224925511a47STejun Heo } 225025511a47STejun Heo 2251c8e55f36STejun Heo worker_leave_idle(worker); 2252db7bccf4STejun Heo recheck: 2253e22bee78STejun Heo /* no more worker necessary? */ 225463d95a91STejun Heo if (!need_more_worker(pool)) 2255e22bee78STejun Heo goto sleep; 2256e22bee78STejun Heo 2257e22bee78STejun Heo /* do we need to manage? */ 225863d95a91STejun Heo if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 2259e22bee78STejun Heo goto recheck; 2260e22bee78STejun Heo 2261c8e55f36STejun Heo /* 2262c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 2263c8e55f36STejun Heo * preparing to process a work or actually processing it. 2264c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 2265c8e55f36STejun Heo */ 22666183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->scheduled)); 2267c8e55f36STejun Heo 2268e22bee78STejun Heo /* 2269e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 2270e22bee78STejun Heo * at least one idle worker or that someone else has already 2271e22bee78STejun Heo * assumed the manager role. 2272e22bee78STejun Heo */ 2273e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 2274e22bee78STejun Heo 2275e22bee78STejun Heo do { 2276affee4b2STejun Heo struct work_struct *work = 2277bd7bdd43STejun Heo list_first_entry(&pool->worklist, 2278affee4b2STejun Heo struct work_struct, entry); 2279affee4b2STejun Heo 2280c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 2281affee4b2STejun Heo /* optimization path, not strictly necessary */ 2282affee4b2STejun Heo process_one_work(worker, work); 2283affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 2284affee4b2STejun Heo process_scheduled_works(worker); 2285affee4b2STejun Heo } else { 2286c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 2287affee4b2STejun Heo process_scheduled_works(worker); 2288affee4b2STejun Heo } 228963d95a91STejun Heo } while (keep_working(pool)); 2290affee4b2STejun Heo 2291e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 2292d313dd85STejun Heo sleep: 229363d95a91STejun Heo if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) 2294e22bee78STejun Heo goto recheck; 2295d313dd85STejun Heo 2296c8e55f36STejun Heo /* 2297d565ed63STejun Heo * pool->lock is held and there's no work to process and no need to 2298d565ed63STejun Heo * manage, sleep. Workers are woken up only while holding 2299d565ed63STejun Heo * pool->lock or from local cpu, so setting the current state 2300d565ed63STejun Heo * before releasing pool->lock is enough to prevent losing any 2301d565ed63STejun Heo * event. 2302c8e55f36STejun Heo */ 2303c8e55f36STejun Heo worker_enter_idle(worker); 2304c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 2305d565ed63STejun Heo spin_unlock_irq(&pool->lock); 23061da177e4SLinus Torvalds schedule(); 2307c8e55f36STejun Heo goto woke_up; 23081da177e4SLinus Torvalds } 23091da177e4SLinus Torvalds 2310e22bee78STejun Heo /** 2311e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2312111c225aSTejun Heo * @__rescuer: self 2313e22bee78STejun Heo * 2314e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2315e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 2316e22bee78STejun Heo * 2317706026c2STejun Heo * Regular work processing on a pool may block trying to create a new 2318e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2319e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2320e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2321e22bee78STejun Heo * the problem rescuer solves. 2322e22bee78STejun Heo * 2323706026c2STejun Heo * When such condition is possible, the pool summons rescuers of all 2324706026c2STejun Heo * workqueues which have works queued on the pool and let them process 2325e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2326e22bee78STejun Heo * 2327e22bee78STejun Heo * This should happen rarely. 2328e22bee78STejun Heo */ 2329111c225aSTejun Heo static int rescuer_thread(void *__rescuer) 2330e22bee78STejun Heo { 2331111c225aSTejun Heo struct worker *rescuer = __rescuer; 2332111c225aSTejun Heo struct workqueue_struct *wq = rescuer->rescue_wq; 2333e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 2334f3421797STejun Heo bool is_unbound = wq->flags & WQ_UNBOUND; 2335e22bee78STejun Heo unsigned int cpu; 2336e22bee78STejun Heo 2337e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2338111c225aSTejun Heo 2339111c225aSTejun Heo /* 2340111c225aSTejun Heo * Mark rescuer as worker too. As WORKER_PREP is never cleared, it 2341111c225aSTejun Heo * doesn't participate in concurrency management. 2342111c225aSTejun Heo */ 2343111c225aSTejun Heo rescuer->task->flags |= PF_WQ_WORKER; 2344e22bee78STejun Heo repeat: 2345e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 23461da177e4SLinus Torvalds 2347412d32e6SMike Galbraith if (kthread_should_stop()) { 2348412d32e6SMike Galbraith __set_current_state(TASK_RUNNING); 2349111c225aSTejun Heo rescuer->task->flags &= ~PF_WQ_WORKER; 2350e22bee78STejun Heo return 0; 2351412d32e6SMike Galbraith } 23521da177e4SLinus Torvalds 2353f3421797STejun Heo /* 2354f3421797STejun Heo * See whether any cpu is asking for help. Unbounded 2355f3421797STejun Heo * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. 2356f3421797STejun Heo */ 2357f2e005aaSTejun Heo for_each_mayday_cpu(cpu, wq->mayday_mask) { 2358f3421797STejun Heo unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 2359112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(tcpu, wq); 2360112202d9STejun Heo struct worker_pool *pool = pwq->pool; 2361e22bee78STejun Heo struct work_struct *work, *n; 2362e22bee78STejun Heo 2363e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2364f2e005aaSTejun Heo mayday_clear_cpu(cpu, wq->mayday_mask); 2365e22bee78STejun Heo 2366e22bee78STejun Heo /* migrate to the target cpu if possible */ 2367f36dc67bSLai Jiangshan worker_maybe_bind_and_lock(pool); 2368b3104104SLai Jiangshan rescuer->pool = pool; 2369e22bee78STejun Heo 2370e22bee78STejun Heo /* 2371e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2372e22bee78STejun Heo * process'em. 2373e22bee78STejun Heo */ 23746183c009STejun Heo WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); 2375bd7bdd43STejun Heo list_for_each_entry_safe(work, n, &pool->worklist, entry) 2376112202d9STejun Heo if (get_work_pwq(work) == pwq) 2377e22bee78STejun Heo move_linked_works(work, scheduled, &n); 2378e22bee78STejun Heo 2379e22bee78STejun Heo process_scheduled_works(rescuer); 23807576958aSTejun Heo 23817576958aSTejun Heo /* 2382d565ed63STejun Heo * Leave this pool. If keep_working() is %true, notify a 23837576958aSTejun Heo * regular worker; otherwise, we end up with 0 concurrency 23847576958aSTejun Heo * and stalling the execution. 23857576958aSTejun Heo */ 238663d95a91STejun Heo if (keep_working(pool)) 238763d95a91STejun Heo wake_up_worker(pool); 23887576958aSTejun Heo 2389b3104104SLai Jiangshan rescuer->pool = NULL; 2390d565ed63STejun Heo spin_unlock_irq(&pool->lock); 23911da177e4SLinus Torvalds } 23921da177e4SLinus Torvalds 2393111c225aSTejun Heo /* rescuers should never participate in concurrency management */ 2394111c225aSTejun Heo WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); 2395e22bee78STejun Heo schedule(); 2396e22bee78STejun Heo goto repeat; 23971da177e4SLinus Torvalds } 23981da177e4SLinus Torvalds 2399fc2e4d70SOleg Nesterov struct wq_barrier { 2400fc2e4d70SOleg Nesterov struct work_struct work; 2401fc2e4d70SOleg Nesterov struct completion done; 2402fc2e4d70SOleg Nesterov }; 2403fc2e4d70SOleg Nesterov 2404fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2405fc2e4d70SOleg Nesterov { 2406fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2407fc2e4d70SOleg Nesterov complete(&barr->done); 2408fc2e4d70SOleg Nesterov } 2409fc2e4d70SOleg Nesterov 24104690c4abSTejun Heo /** 24114690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 2412112202d9STejun Heo * @pwq: pwq to insert barrier into 24134690c4abSTejun Heo * @barr: wq_barrier to insert 2414affee4b2STejun Heo * @target: target work to attach @barr to 2415affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 24164690c4abSTejun Heo * 2417affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2418affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2419affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2420affee4b2STejun Heo * cpu. 2421affee4b2STejun Heo * 2422affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2423affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2424affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2425affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2426affee4b2STejun Heo * after a work with LINKED flag set. 2427affee4b2STejun Heo * 2428affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2429112202d9STejun Heo * underneath us, so we can't reliably determine pwq from @target. 24304690c4abSTejun Heo * 24314690c4abSTejun Heo * CONTEXT: 2432d565ed63STejun Heo * spin_lock_irq(pool->lock). 24334690c4abSTejun Heo */ 2434112202d9STejun Heo static void insert_wq_barrier(struct pool_workqueue *pwq, 2435affee4b2STejun Heo struct wq_barrier *barr, 2436affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2437fc2e4d70SOleg Nesterov { 2438affee4b2STejun Heo struct list_head *head; 2439affee4b2STejun Heo unsigned int linked = 0; 2440affee4b2STejun Heo 2441dc186ad7SThomas Gleixner /* 2442d565ed63STejun Heo * debugobject calls are safe here even with pool->lock locked 2443dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2444dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2445dc186ad7SThomas Gleixner * might deadlock. 2446dc186ad7SThomas Gleixner */ 2447ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 244822df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2449fc2e4d70SOleg Nesterov init_completion(&barr->done); 245083c22520SOleg Nesterov 2451affee4b2STejun Heo /* 2452affee4b2STejun Heo * If @target is currently being executed, schedule the 2453affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2454affee4b2STejun Heo */ 2455affee4b2STejun Heo if (worker) 2456affee4b2STejun Heo head = worker->scheduled.next; 2457affee4b2STejun Heo else { 2458affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2459affee4b2STejun Heo 2460affee4b2STejun Heo head = target->entry.next; 2461affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2462affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2463affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2464affee4b2STejun Heo } 2465affee4b2STejun Heo 2466dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2467112202d9STejun Heo insert_work(pwq, &barr->work, head, 2468affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2469fc2e4d70SOleg Nesterov } 2470fc2e4d70SOleg Nesterov 247173f53c4aSTejun Heo /** 2472112202d9STejun Heo * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing 247373f53c4aSTejun Heo * @wq: workqueue being flushed 247473f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 247573f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 247673f53c4aSTejun Heo * 2477112202d9STejun Heo * Prepare pwqs for workqueue flushing. 247873f53c4aSTejun Heo * 2479112202d9STejun Heo * If @flush_color is non-negative, flush_color on all pwqs should be 2480112202d9STejun Heo * -1. If no pwq has in-flight commands at the specified color, all 2481112202d9STejun Heo * pwq->flush_color's stay at -1 and %false is returned. If any pwq 2482112202d9STejun Heo * has in flight commands, its pwq->flush_color is set to 2483112202d9STejun Heo * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq 248473f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 248573f53c4aSTejun Heo * 248673f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 248773f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 248873f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 248973f53c4aSTejun Heo * is returned. 249073f53c4aSTejun Heo * 2491112202d9STejun Heo * If @work_color is non-negative, all pwqs should have the same 249273f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 249373f53c4aSTejun Heo * advanced to @work_color. 249473f53c4aSTejun Heo * 249573f53c4aSTejun Heo * CONTEXT: 249673f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 249773f53c4aSTejun Heo * 249873f53c4aSTejun Heo * RETURNS: 249973f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 250073f53c4aSTejun Heo * otherwise. 250173f53c4aSTejun Heo */ 2502112202d9STejun Heo static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, 250373f53c4aSTejun Heo int flush_color, int work_color) 25041da177e4SLinus Torvalds { 250573f53c4aSTejun Heo bool wait = false; 250673f53c4aSTejun Heo unsigned int cpu; 25071da177e4SLinus Torvalds 250873f53c4aSTejun Heo if (flush_color >= 0) { 25096183c009STejun Heo WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); 2510112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 1); 2511dc186ad7SThomas Gleixner } 251214441960SOleg Nesterov 2513112202d9STejun Heo for_each_pwq_cpu(cpu, wq) { 2514112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 2515112202d9STejun Heo struct worker_pool *pool = pwq->pool; 25161da177e4SLinus Torvalds 2517d565ed63STejun Heo spin_lock_irq(&pool->lock); 251873f53c4aSTejun Heo 251973f53c4aSTejun Heo if (flush_color >= 0) { 25206183c009STejun Heo WARN_ON_ONCE(pwq->flush_color != -1); 252173f53c4aSTejun Heo 2522112202d9STejun Heo if (pwq->nr_in_flight[flush_color]) { 2523112202d9STejun Heo pwq->flush_color = flush_color; 2524112202d9STejun Heo atomic_inc(&wq->nr_pwqs_to_flush); 252573f53c4aSTejun Heo wait = true; 25261da177e4SLinus Torvalds } 252773f53c4aSTejun Heo } 252873f53c4aSTejun Heo 252973f53c4aSTejun Heo if (work_color >= 0) { 25306183c009STejun Heo WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); 2531112202d9STejun Heo pwq->work_color = work_color; 253273f53c4aSTejun Heo } 253373f53c4aSTejun Heo 2534d565ed63STejun Heo spin_unlock_irq(&pool->lock); 25351da177e4SLinus Torvalds } 25361da177e4SLinus Torvalds 2537112202d9STejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) 253873f53c4aSTejun Heo complete(&wq->first_flusher->done); 253973f53c4aSTejun Heo 254073f53c4aSTejun Heo return wait; 254183c22520SOleg Nesterov } 25421da177e4SLinus Torvalds 25430fcb78c2SRolf Eike Beer /** 25441da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 25450fcb78c2SRolf Eike Beer * @wq: workqueue to flush 25461da177e4SLinus Torvalds * 25471da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 25481da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 25491da177e4SLinus Torvalds * 2550fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2551fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 25521da177e4SLinus Torvalds */ 25537ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 25541da177e4SLinus Torvalds { 255573f53c4aSTejun Heo struct wq_flusher this_flusher = { 255673f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 255773f53c4aSTejun Heo .flush_color = -1, 255873f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 255973f53c4aSTejun Heo }; 256073f53c4aSTejun Heo int next_color; 2561b1f4ec17SOleg Nesterov 25623295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 25633295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 256473f53c4aSTejun Heo 256573f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 256673f53c4aSTejun Heo 256773f53c4aSTejun Heo /* 256873f53c4aSTejun Heo * Start-to-wait phase 256973f53c4aSTejun Heo */ 257073f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 257173f53c4aSTejun Heo 257273f53c4aSTejun Heo if (next_color != wq->flush_color) { 257373f53c4aSTejun Heo /* 257473f53c4aSTejun Heo * Color space is not full. The current work_color 257573f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 257673f53c4aSTejun Heo * by one. 257773f53c4aSTejun Heo */ 25786183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); 257973f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 258073f53c4aSTejun Heo wq->work_color = next_color; 258173f53c4aSTejun Heo 258273f53c4aSTejun Heo if (!wq->first_flusher) { 258373f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 25846183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 258573f53c4aSTejun Heo 258673f53c4aSTejun Heo wq->first_flusher = &this_flusher; 258773f53c4aSTejun Heo 2588112202d9STejun Heo if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, 258973f53c4aSTejun Heo wq->work_color)) { 259073f53c4aSTejun Heo /* nothing to flush, done */ 259173f53c4aSTejun Heo wq->flush_color = next_color; 259273f53c4aSTejun Heo wq->first_flusher = NULL; 259373f53c4aSTejun Heo goto out_unlock; 259473f53c4aSTejun Heo } 259573f53c4aSTejun Heo } else { 259673f53c4aSTejun Heo /* wait in queue */ 25976183c009STejun Heo WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); 259873f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 2599112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 260073f53c4aSTejun Heo } 260173f53c4aSTejun Heo } else { 260273f53c4aSTejun Heo /* 260373f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 260473f53c4aSTejun Heo * The next flush completion will assign us 260573f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 260673f53c4aSTejun Heo */ 260773f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 260873f53c4aSTejun Heo } 260973f53c4aSTejun Heo 261073f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 261173f53c4aSTejun Heo 261273f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 261373f53c4aSTejun Heo 261473f53c4aSTejun Heo /* 261573f53c4aSTejun Heo * Wake-up-and-cascade phase 261673f53c4aSTejun Heo * 261773f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 261873f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 261973f53c4aSTejun Heo */ 262073f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 262173f53c4aSTejun Heo return; 262273f53c4aSTejun Heo 262373f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 262473f53c4aSTejun Heo 26254ce48b37STejun Heo /* we might have raced, check again with mutex held */ 26264ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 26274ce48b37STejun Heo goto out_unlock; 26284ce48b37STejun Heo 262973f53c4aSTejun Heo wq->first_flusher = NULL; 263073f53c4aSTejun Heo 26316183c009STejun Heo WARN_ON_ONCE(!list_empty(&this_flusher.list)); 26326183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 263373f53c4aSTejun Heo 263473f53c4aSTejun Heo while (true) { 263573f53c4aSTejun Heo struct wq_flusher *next, *tmp; 263673f53c4aSTejun Heo 263773f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 263873f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 263973f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 264073f53c4aSTejun Heo break; 264173f53c4aSTejun Heo list_del_init(&next->list); 264273f53c4aSTejun Heo complete(&next->done); 264373f53c4aSTejun Heo } 264473f53c4aSTejun Heo 26456183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && 264673f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 264773f53c4aSTejun Heo 264873f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 264973f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 265073f53c4aSTejun Heo 265173f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 265273f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 265373f53c4aSTejun Heo /* 265473f53c4aSTejun Heo * Assign the same color to all overflowed 265573f53c4aSTejun Heo * flushers, advance work_color and append to 265673f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 265773f53c4aSTejun Heo * phase for these overflowed flushers. 265873f53c4aSTejun Heo */ 265973f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 266073f53c4aSTejun Heo tmp->flush_color = wq->work_color; 266173f53c4aSTejun Heo 266273f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 266373f53c4aSTejun Heo 266473f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 266573f53c4aSTejun Heo &wq->flusher_queue); 2666112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 266773f53c4aSTejun Heo } 266873f53c4aSTejun Heo 266973f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 26706183c009STejun Heo WARN_ON_ONCE(wq->flush_color != wq->work_color); 267173f53c4aSTejun Heo break; 267273f53c4aSTejun Heo } 267373f53c4aSTejun Heo 267473f53c4aSTejun Heo /* 267573f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 2676112202d9STejun Heo * the new first flusher and arm pwqs. 267773f53c4aSTejun Heo */ 26786183c009STejun Heo WARN_ON_ONCE(wq->flush_color == wq->work_color); 26796183c009STejun Heo WARN_ON_ONCE(wq->flush_color != next->flush_color); 268073f53c4aSTejun Heo 268173f53c4aSTejun Heo list_del_init(&next->list); 268273f53c4aSTejun Heo wq->first_flusher = next; 268373f53c4aSTejun Heo 2684112202d9STejun Heo if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) 268573f53c4aSTejun Heo break; 268673f53c4aSTejun Heo 268773f53c4aSTejun Heo /* 268873f53c4aSTejun Heo * Meh... this color is already done, clear first 268973f53c4aSTejun Heo * flusher and repeat cascading. 269073f53c4aSTejun Heo */ 269173f53c4aSTejun Heo wq->first_flusher = NULL; 269273f53c4aSTejun Heo } 269373f53c4aSTejun Heo 269473f53c4aSTejun Heo out_unlock: 269573f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 26961da177e4SLinus Torvalds } 2697ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 26981da177e4SLinus Torvalds 26999c5a2ba7STejun Heo /** 27009c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 27019c5a2ba7STejun Heo * @wq: workqueue to drain 27029c5a2ba7STejun Heo * 27039c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 27049c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 27059c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 27069c5a2ba7STejun Heo * repeatedly until it becomes empty. The number of flushing is detemined 27079c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 27089c5a2ba7STejun Heo * takes too long. 27099c5a2ba7STejun Heo */ 27109c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 27119c5a2ba7STejun Heo { 27129c5a2ba7STejun Heo unsigned int flush_cnt = 0; 27139c5a2ba7STejun Heo unsigned int cpu; 27149c5a2ba7STejun Heo 27159c5a2ba7STejun Heo /* 27169c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 27179c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 27189c5a2ba7STejun Heo * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. 27199c5a2ba7STejun Heo */ 2720e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 27219c5a2ba7STejun Heo if (!wq->nr_drainers++) 27229c5a2ba7STejun Heo wq->flags |= WQ_DRAINING; 2723e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 27249c5a2ba7STejun Heo reflush: 27259c5a2ba7STejun Heo flush_workqueue(wq); 27269c5a2ba7STejun Heo 2727112202d9STejun Heo for_each_pwq_cpu(cpu, wq) { 2728112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 2729fa2563e4SThomas Tuttle bool drained; 27309c5a2ba7STejun Heo 2731112202d9STejun Heo spin_lock_irq(&pwq->pool->lock); 2732112202d9STejun Heo drained = !pwq->nr_active && list_empty(&pwq->delayed_works); 2733112202d9STejun Heo spin_unlock_irq(&pwq->pool->lock); 2734fa2563e4SThomas Tuttle 2735fa2563e4SThomas Tuttle if (drained) 27369c5a2ba7STejun Heo continue; 27379c5a2ba7STejun Heo 27389c5a2ba7STejun Heo if (++flush_cnt == 10 || 27399c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 2740044c782cSValentin Ilie pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n", 27419c5a2ba7STejun Heo wq->name, flush_cnt); 27429c5a2ba7STejun Heo goto reflush; 27439c5a2ba7STejun Heo } 27449c5a2ba7STejun Heo 2745e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 27469c5a2ba7STejun Heo if (!--wq->nr_drainers) 27479c5a2ba7STejun Heo wq->flags &= ~WQ_DRAINING; 2748e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 27499c5a2ba7STejun Heo } 27509c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 27519c5a2ba7STejun Heo 2752606a5020STejun Heo static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) 2753baf59022STejun Heo { 2754baf59022STejun Heo struct worker *worker = NULL; 2755c9e7cf27STejun Heo struct worker_pool *pool; 2756112202d9STejun Heo struct pool_workqueue *pwq; 2757baf59022STejun Heo 2758baf59022STejun Heo might_sleep(); 2759c9e7cf27STejun Heo pool = get_work_pool(work); 2760c9e7cf27STejun Heo if (!pool) 2761baf59022STejun Heo return false; 2762baf59022STejun Heo 2763d565ed63STejun Heo spin_lock_irq(&pool->lock); 27640b3dae68SLai Jiangshan /* see the comment in try_to_grab_pending() with the same code */ 2765112202d9STejun Heo pwq = get_work_pwq(work); 2766112202d9STejun Heo if (pwq) { 2767112202d9STejun Heo if (unlikely(pwq->pool != pool)) 2768baf59022STejun Heo goto already_gone; 2769606a5020STejun Heo } else { 2770c9e7cf27STejun Heo worker = find_worker_executing_work(pool, work); 2771baf59022STejun Heo if (!worker) 2772baf59022STejun Heo goto already_gone; 2773112202d9STejun Heo pwq = worker->current_pwq; 2774606a5020STejun Heo } 2775baf59022STejun Heo 2776112202d9STejun Heo insert_wq_barrier(pwq, barr, work, worker); 2777d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2778baf59022STejun Heo 2779e159489bSTejun Heo /* 2780e159489bSTejun Heo * If @max_active is 1 or rescuer is in use, flushing another work 2781e159489bSTejun Heo * item on the same workqueue may lead to deadlock. Make sure the 2782e159489bSTejun Heo * flusher is not running on the same workqueue by verifying write 2783e159489bSTejun Heo * access. 2784e159489bSTejun Heo */ 2785112202d9STejun Heo if (pwq->wq->saved_max_active == 1 || pwq->wq->flags & WQ_RESCUER) 2786112202d9STejun Heo lock_map_acquire(&pwq->wq->lockdep_map); 2787e159489bSTejun Heo else 2788112202d9STejun Heo lock_map_acquire_read(&pwq->wq->lockdep_map); 2789112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 2790e159489bSTejun Heo 2791baf59022STejun Heo return true; 2792baf59022STejun Heo already_gone: 2793d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2794baf59022STejun Heo return false; 2795baf59022STejun Heo } 2796baf59022STejun Heo 2797db700897SOleg Nesterov /** 2798401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 2799401a8d04STejun Heo * @work: the work to flush 2800db700897SOleg Nesterov * 2801606a5020STejun Heo * Wait until @work has finished execution. @work is guaranteed to be idle 2802606a5020STejun Heo * on return if it hasn't been requeued since flush started. 2803401a8d04STejun Heo * 2804401a8d04STejun Heo * RETURNS: 2805401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2806401a8d04STejun Heo * %false if it was already idle. 2807db700897SOleg Nesterov */ 2808401a8d04STejun Heo bool flush_work(struct work_struct *work) 2809db700897SOleg Nesterov { 2810db700897SOleg Nesterov struct wq_barrier barr; 2811db700897SOleg Nesterov 28120976dfc1SStephen Boyd lock_map_acquire(&work->lockdep_map); 28130976dfc1SStephen Boyd lock_map_release(&work->lockdep_map); 28140976dfc1SStephen Boyd 2815606a5020STejun Heo if (start_flush_work(work, &barr)) { 2816db700897SOleg Nesterov wait_for_completion(&barr.done); 2817dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2818401a8d04STejun Heo return true; 2819606a5020STejun Heo } else { 2820401a8d04STejun Heo return false; 2821db700897SOleg Nesterov } 2822606a5020STejun Heo } 2823db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2824db700897SOleg Nesterov 282536e227d2STejun Heo static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 2826401a8d04STejun Heo { 2827bbb68dfaSTejun Heo unsigned long flags; 28281f1f642eSOleg Nesterov int ret; 28291f1f642eSOleg Nesterov 28301f1f642eSOleg Nesterov do { 2831bbb68dfaSTejun Heo ret = try_to_grab_pending(work, is_dwork, &flags); 2832bbb68dfaSTejun Heo /* 2833bbb68dfaSTejun Heo * If someone else is canceling, wait for the same event it 2834bbb68dfaSTejun Heo * would be waiting for before retrying. 2835bbb68dfaSTejun Heo */ 2836bbb68dfaSTejun Heo if (unlikely(ret == -ENOENT)) 2837606a5020STejun Heo flush_work(work); 28381f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 28391f1f642eSOleg Nesterov 2840bbb68dfaSTejun Heo /* tell other tasks trying to grab @work to back off */ 2841bbb68dfaSTejun Heo mark_work_canceling(work); 2842bbb68dfaSTejun Heo local_irq_restore(flags); 2843bbb68dfaSTejun Heo 2844606a5020STejun Heo flush_work(work); 28457a22ad75STejun Heo clear_work_data(work); 28461f1f642eSOleg Nesterov return ret; 28471f1f642eSOleg Nesterov } 28481f1f642eSOleg Nesterov 28496e84d644SOleg Nesterov /** 2850401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 2851401a8d04STejun Heo * @work: the work to cancel 28526e84d644SOleg Nesterov * 2853401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 2854401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 2855401a8d04STejun Heo * another workqueue. On return from this function, @work is 2856401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 28571f1f642eSOleg Nesterov * 2858401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 2859401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 28606e84d644SOleg Nesterov * 2861401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 28626e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 2863401a8d04STejun Heo * 2864401a8d04STejun Heo * RETURNS: 2865401a8d04STejun Heo * %true if @work was pending, %false otherwise. 28666e84d644SOleg Nesterov */ 2867401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 28686e84d644SOleg Nesterov { 286936e227d2STejun Heo return __cancel_work_timer(work, false); 2870b89deed3SOleg Nesterov } 287128e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2872b89deed3SOleg Nesterov 28736e84d644SOleg Nesterov /** 2874401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 2875401a8d04STejun Heo * @dwork: the delayed work to flush 28766e84d644SOleg Nesterov * 2877401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 2878401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 2879401a8d04STejun Heo * considers the last queueing instance of @dwork. 28801f1f642eSOleg Nesterov * 2881401a8d04STejun Heo * RETURNS: 2882401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2883401a8d04STejun Heo * %false if it was already idle. 28846e84d644SOleg Nesterov */ 2885401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 2886401a8d04STejun Heo { 28878930cabaSTejun Heo local_irq_disable(); 2888401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 288960c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 28908930cabaSTejun Heo local_irq_enable(); 2891401a8d04STejun Heo return flush_work(&dwork->work); 2892401a8d04STejun Heo } 2893401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 2894401a8d04STejun Heo 2895401a8d04STejun Heo /** 289657b30ae7STejun Heo * cancel_delayed_work - cancel a delayed work 289757b30ae7STejun Heo * @dwork: delayed_work to cancel 289809383498STejun Heo * 289957b30ae7STejun Heo * Kill off a pending delayed_work. Returns %true if @dwork was pending 290057b30ae7STejun Heo * and canceled; %false if wasn't pending. Note that the work callback 290157b30ae7STejun Heo * function may still be running on return, unless it returns %true and the 290257b30ae7STejun Heo * work doesn't re-arm itself. Explicitly flush or use 290357b30ae7STejun Heo * cancel_delayed_work_sync() to wait on it. 290409383498STejun Heo * 290557b30ae7STejun Heo * This function is safe to call from any context including IRQ handler. 290609383498STejun Heo */ 290757b30ae7STejun Heo bool cancel_delayed_work(struct delayed_work *dwork) 290809383498STejun Heo { 290957b30ae7STejun Heo unsigned long flags; 291057b30ae7STejun Heo int ret; 291157b30ae7STejun Heo 291257b30ae7STejun Heo do { 291357b30ae7STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 291457b30ae7STejun Heo } while (unlikely(ret == -EAGAIN)); 291557b30ae7STejun Heo 291657b30ae7STejun Heo if (unlikely(ret < 0)) 291757b30ae7STejun Heo return false; 291857b30ae7STejun Heo 29197c3eed5cSTejun Heo set_work_pool_and_clear_pending(&dwork->work, 29207c3eed5cSTejun Heo get_work_pool_id(&dwork->work)); 292157b30ae7STejun Heo local_irq_restore(flags); 2922c0158ca6SDan Magenheimer return ret; 292309383498STejun Heo } 292457b30ae7STejun Heo EXPORT_SYMBOL(cancel_delayed_work); 292509383498STejun Heo 292609383498STejun Heo /** 2927401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 2928401a8d04STejun Heo * @dwork: the delayed work cancel 2929401a8d04STejun Heo * 2930401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 2931401a8d04STejun Heo * 2932401a8d04STejun Heo * RETURNS: 2933401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 2934401a8d04STejun Heo */ 2935401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 29366e84d644SOleg Nesterov { 293736e227d2STejun Heo return __cancel_work_timer(&dwork->work, true); 29386e84d644SOleg Nesterov } 2939f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 29401da177e4SLinus Torvalds 29410fcb78c2SRolf Eike Beer /** 2942c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2943c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2944c1a220e7SZhang Rui * @work: job to be done 2945c1a220e7SZhang Rui * 2946c1a220e7SZhang Rui * This puts a job on a specific cpu 2947c1a220e7SZhang Rui */ 2948d4283e93STejun Heo bool schedule_work_on(int cpu, struct work_struct *work) 2949c1a220e7SZhang Rui { 2950d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 2951c1a220e7SZhang Rui } 2952c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 2953c1a220e7SZhang Rui 29540fcb78c2SRolf Eike Beer /** 2955ae90dd5dSDave Jones * schedule_work - put work task in global workqueue 29561da177e4SLinus Torvalds * @work: job to be done 29571da177e4SLinus Torvalds * 2958d4283e93STejun Heo * Returns %false if @work was already on the kernel-global workqueue and 2959d4283e93STejun Heo * %true otherwise. 296052bad64dSDavid Howells * 29610fcb78c2SRolf Eike Beer * This puts a job in the kernel-global workqueue if it was not already 29620fcb78c2SRolf Eike Beer * queued and leaves it in the same position on the kernel-global 29630fcb78c2SRolf Eike Beer * workqueue otherwise. 29641da177e4SLinus Torvalds */ 2965d4283e93STejun Heo bool schedule_work(struct work_struct *work) 29661da177e4SLinus Torvalds { 29670fcb78c2SRolf Eike Beer return queue_work(system_wq, work); 29681da177e4SLinus Torvalds } 29690fcb78c2SRolf Eike Beer EXPORT_SYMBOL(schedule_work); 29701da177e4SLinus Torvalds 29710fcb78c2SRolf Eike Beer /** 29720fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 29730fcb78c2SRolf Eike Beer * @cpu: cpu to use 29740fcb78c2SRolf Eike Beer * @dwork: job to be done 29750fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 29760fcb78c2SRolf Eike Beer * 29770fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 29780fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 29790fcb78c2SRolf Eike Beer */ 2980d4283e93STejun Heo bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork, 2981d4283e93STejun Heo unsigned long delay) 29821da177e4SLinus Torvalds { 2983d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 29841da177e4SLinus Torvalds } 2985ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 29861da177e4SLinus Torvalds 2987b6136773SAndrew Morton /** 29880a13c00eSTejun Heo * schedule_delayed_work - put work task in global workqueue after delay 29890a13c00eSTejun Heo * @dwork: job to be done 29900a13c00eSTejun Heo * @delay: number of jiffies to wait or 0 for immediate execution 29910a13c00eSTejun Heo * 29920a13c00eSTejun Heo * After waiting for a given time this puts a job in the kernel-global 29930a13c00eSTejun Heo * workqueue. 29940a13c00eSTejun Heo */ 2995d4283e93STejun Heo bool schedule_delayed_work(struct delayed_work *dwork, unsigned long delay) 29960a13c00eSTejun Heo { 29970a13c00eSTejun Heo return queue_delayed_work(system_wq, dwork, delay); 29980a13c00eSTejun Heo } 29990a13c00eSTejun Heo EXPORT_SYMBOL(schedule_delayed_work); 30000a13c00eSTejun Heo 30010a13c00eSTejun Heo /** 300231ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 3003b6136773SAndrew Morton * @func: the function to call 3004b6136773SAndrew Morton * 300531ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 300631ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 3007b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 300831ddd871STejun Heo * 300931ddd871STejun Heo * RETURNS: 301031ddd871STejun Heo * 0 on success, -errno on failure. 3011b6136773SAndrew Morton */ 301265f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 301315316ba8SChristoph Lameter { 301415316ba8SChristoph Lameter int cpu; 301538f51568SNamhyung Kim struct work_struct __percpu *works; 301615316ba8SChristoph Lameter 3017b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 3018b6136773SAndrew Morton if (!works) 301915316ba8SChristoph Lameter return -ENOMEM; 3020b6136773SAndrew Morton 302195402b38SGautham R Shenoy get_online_cpus(); 302293981800STejun Heo 302315316ba8SChristoph Lameter for_each_online_cpu(cpu) { 30249bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 30259bfb1839SIngo Molnar 30269bfb1839SIngo Molnar INIT_WORK(work, func); 30278de6d308SOleg Nesterov schedule_work_on(cpu, work); 302815316ba8SChristoph Lameter } 302993981800STejun Heo 303093981800STejun Heo for_each_online_cpu(cpu) 30318616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 303293981800STejun Heo 303395402b38SGautham R Shenoy put_online_cpus(); 3034b6136773SAndrew Morton free_percpu(works); 303515316ba8SChristoph Lameter return 0; 303615316ba8SChristoph Lameter } 303715316ba8SChristoph Lameter 3038eef6a7d5SAlan Stern /** 3039eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 3040eef6a7d5SAlan Stern * 3041eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 3042eef6a7d5SAlan Stern * completion. 3043eef6a7d5SAlan Stern * 3044eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 3045eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 3046eef6a7d5SAlan Stern * will lead to deadlock: 3047eef6a7d5SAlan Stern * 3048eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 3049eef6a7d5SAlan Stern * a lock held by your code or its caller. 3050eef6a7d5SAlan Stern * 3051eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 3052eef6a7d5SAlan Stern * 3053eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 3054eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 3055eef6a7d5SAlan Stern * what locks they need, which you have no control over. 3056eef6a7d5SAlan Stern * 3057eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 3058eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 3059eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 3060eef6a7d5SAlan Stern * cancel_work_sync() instead. 3061eef6a7d5SAlan Stern */ 30621da177e4SLinus Torvalds void flush_scheduled_work(void) 30631da177e4SLinus Torvalds { 3064d320c038STejun Heo flush_workqueue(system_wq); 30651da177e4SLinus Torvalds } 3066ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 30671da177e4SLinus Torvalds 30681da177e4SLinus Torvalds /** 30691fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 30701fa44ecaSJames Bottomley * @fn: the function to execute 30711fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 30721fa44ecaSJames Bottomley * be available when the work executes) 30731fa44ecaSJames Bottomley * 30741fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 30751fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 30761fa44ecaSJames Bottomley * 30771fa44ecaSJames Bottomley * Returns: 0 - function was executed 30781fa44ecaSJames Bottomley * 1 - function was scheduled for execution 30791fa44ecaSJames Bottomley */ 308065f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 30811fa44ecaSJames Bottomley { 30821fa44ecaSJames Bottomley if (!in_interrupt()) { 308365f27f38SDavid Howells fn(&ew->work); 30841fa44ecaSJames Bottomley return 0; 30851fa44ecaSJames Bottomley } 30861fa44ecaSJames Bottomley 308765f27f38SDavid Howells INIT_WORK(&ew->work, fn); 30881fa44ecaSJames Bottomley schedule_work(&ew->work); 30891fa44ecaSJames Bottomley 30901fa44ecaSJames Bottomley return 1; 30911fa44ecaSJames Bottomley } 30921fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 30931fa44ecaSJames Bottomley 30941da177e4SLinus Torvalds int keventd_up(void) 30951da177e4SLinus Torvalds { 3096d320c038STejun Heo return system_wq != NULL; 30971da177e4SLinus Torvalds } 30981da177e4SLinus Torvalds 3099112202d9STejun Heo static int alloc_pwqs(struct workqueue_struct *wq) 31001da177e4SLinus Torvalds { 3101e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 3102e904e6c2STejun Heo wq->pool_wq.pcpu = alloc_percpu(struct pool_workqueue); 3103e904e6c2STejun Heo else 3104e904e6c2STejun Heo wq->pool_wq.single = kmem_cache_zalloc(pwq_cache, GFP_KERNEL); 3105e1d8aa9fSFrederic Weisbecker 3106112202d9STejun Heo return wq->pool_wq.v ? 0 : -ENOMEM; 31070f900049STejun Heo } 31080f900049STejun Heo 3109112202d9STejun Heo static void free_pwqs(struct workqueue_struct *wq) 311006ba38a9SOleg Nesterov { 3111e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 3112112202d9STejun Heo free_percpu(wq->pool_wq.pcpu); 3113e904e6c2STejun Heo else 3114e904e6c2STejun Heo kmem_cache_free(pwq_cache, wq->pool_wq.single); 311506ba38a9SOleg Nesterov } 311606ba38a9SOleg Nesterov 3117f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 3118f3421797STejun Heo const char *name) 3119b71ab8c2STejun Heo { 3120f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 3121f3421797STejun Heo 3122f3421797STejun Heo if (max_active < 1 || max_active > lim) 3123044c782cSValentin Ilie pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 3124f3421797STejun Heo max_active, name, 1, lim); 3125b71ab8c2STejun Heo 3126f3421797STejun Heo return clamp_val(max_active, 1, lim); 3127b71ab8c2STejun Heo } 3128b71ab8c2STejun Heo 3129b196be89STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *fmt, 313097e37d7bSTejun Heo unsigned int flags, 31311e19ffc6STejun Heo int max_active, 3132eb13ba87SJohannes Berg struct lock_class_key *key, 3133b196be89STejun Heo const char *lock_name, ...) 31343af24433SOleg Nesterov { 3135b196be89STejun Heo va_list args, args1; 31363af24433SOleg Nesterov struct workqueue_struct *wq; 3137c34056a3STejun Heo unsigned int cpu; 3138b196be89STejun Heo size_t namelen; 3139b196be89STejun Heo 3140b196be89STejun Heo /* determine namelen, allocate wq and format name */ 3141b196be89STejun Heo va_start(args, lock_name); 3142b196be89STejun Heo va_copy(args1, args); 3143b196be89STejun Heo namelen = vsnprintf(NULL, 0, fmt, args) + 1; 3144b196be89STejun Heo 3145b196be89STejun Heo wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL); 3146b196be89STejun Heo if (!wq) 3147b196be89STejun Heo goto err; 3148b196be89STejun Heo 3149b196be89STejun Heo vsnprintf(wq->name, namelen, fmt, args1); 3150b196be89STejun Heo va_end(args); 3151b196be89STejun Heo va_end(args1); 31523af24433SOleg Nesterov 3153f3421797STejun Heo /* 31546370a6adSTejun Heo * Workqueues which may be used during memory reclaim should 31556370a6adSTejun Heo * have a rescuer to guarantee forward progress. 31566370a6adSTejun Heo */ 31576370a6adSTejun Heo if (flags & WQ_MEM_RECLAIM) 31586370a6adSTejun Heo flags |= WQ_RESCUER; 31596370a6adSTejun Heo 3160d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 3161b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 31623af24433SOleg Nesterov 3163b196be89STejun Heo /* init wq */ 316497e37d7bSTejun Heo wq->flags = flags; 3165a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 316673f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 3167112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 0); 316873f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 316973f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 31703af24433SOleg Nesterov 3171eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 3172cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 31733af24433SOleg Nesterov 3174112202d9STejun Heo if (alloc_pwqs(wq) < 0) 3175bdbc5dd7STejun Heo goto err; 3176bdbc5dd7STejun Heo 3177112202d9STejun Heo for_each_pwq_cpu(cpu, wq) { 3178112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 31791537663fSTejun Heo 3180112202d9STejun Heo BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); 3181112202d9STejun Heo pwq->pool = get_std_worker_pool(cpu, flags & WQ_HIGHPRI); 3182112202d9STejun Heo pwq->wq = wq; 3183112202d9STejun Heo pwq->flush_color = -1; 3184112202d9STejun Heo pwq->max_active = max_active; 3185112202d9STejun Heo INIT_LIST_HEAD(&pwq->delayed_works); 3186e22bee78STejun Heo } 31871537663fSTejun Heo 3188e22bee78STejun Heo if (flags & WQ_RESCUER) { 3189e22bee78STejun Heo struct worker *rescuer; 3190e22bee78STejun Heo 3191f2e005aaSTejun Heo if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) 3192e22bee78STejun Heo goto err; 3193e22bee78STejun Heo 3194e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 3195e22bee78STejun Heo if (!rescuer) 3196e22bee78STejun Heo goto err; 3197e22bee78STejun Heo 3198111c225aSTejun Heo rescuer->rescue_wq = wq; 3199111c225aSTejun Heo rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", 3200b196be89STejun Heo wq->name); 3201e22bee78STejun Heo if (IS_ERR(rescuer->task)) 3202e22bee78STejun Heo goto err; 3203e22bee78STejun Heo 3204e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 3205e22bee78STejun Heo wake_up_process(rescuer->task); 32063af24433SOleg Nesterov } 32071537663fSTejun Heo 32083af24433SOleg Nesterov /* 3209a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 3210a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 3211a0a1a5fdSTejun Heo * workqueue to workqueues list. 32123af24433SOleg Nesterov */ 3213e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3214a0a1a5fdSTejun Heo 321558a69cb4STejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZABLE) 3216112202d9STejun Heo for_each_pwq_cpu(cpu, wq) 3217112202d9STejun Heo get_pwq(cpu, wq)->max_active = 0; 3218a0a1a5fdSTejun Heo 32193af24433SOleg Nesterov list_add(&wq->list, &workqueues); 3220a0a1a5fdSTejun Heo 3221e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 32223af24433SOleg Nesterov 32233af24433SOleg Nesterov return wq; 32244690c4abSTejun Heo err: 32254690c4abSTejun Heo if (wq) { 3226112202d9STejun Heo free_pwqs(wq); 3227f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 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 { 3243c8e55f36STejun Heo unsigned int cpu; 32443af24433SOleg Nesterov 32459c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 32469c5a2ba7STejun Heo drain_workqueue(wq); 3247c8efcc25STejun Heo 32486183c009STejun Heo /* sanity checks */ 32496183c009STejun Heo for_each_pwq_cpu(cpu, wq) { 32506183c009STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 32516183c009STejun Heo int i; 32526183c009STejun Heo 32536183c009STejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 32546183c009STejun Heo if (WARN_ON(pwq->nr_in_flight[i])) 32556183c009STejun Heo return; 32566183c009STejun Heo if (WARN_ON(pwq->nr_active) || 32576183c009STejun Heo WARN_ON(!list_empty(&pwq->delayed_works))) 32586183c009STejun Heo return; 32596183c009STejun Heo } 32606183c009STejun Heo 3261a0a1a5fdSTejun Heo /* 3262a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 3263a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 3264a0a1a5fdSTejun Heo */ 3265e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 32663af24433SOleg Nesterov list_del(&wq->list); 3267e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 32683af24433SOleg Nesterov 3269e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 3270e22bee78STejun Heo kthread_stop(wq->rescuer->task); 3271f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 32728d9df9f0SXiaotian Feng kfree(wq->rescuer); 3273e22bee78STejun Heo } 3274e22bee78STejun Heo 3275112202d9STejun Heo free_pwqs(wq); 32763af24433SOleg Nesterov kfree(wq); 32773af24433SOleg Nesterov } 32783af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 32793af24433SOleg Nesterov 3280dcd989cbSTejun Heo /** 3281112202d9STejun Heo * pwq_set_max_active - adjust max_active of a pwq 3282112202d9STejun Heo * @pwq: target pool_workqueue 32839f4bd4cdSLai Jiangshan * @max_active: new max_active value. 32849f4bd4cdSLai Jiangshan * 3285112202d9STejun Heo * Set @pwq->max_active to @max_active and activate delayed works if 32869f4bd4cdSLai Jiangshan * increased. 32879f4bd4cdSLai Jiangshan * 32889f4bd4cdSLai Jiangshan * CONTEXT: 3289d565ed63STejun Heo * spin_lock_irq(pool->lock). 32909f4bd4cdSLai Jiangshan */ 3291112202d9STejun Heo static void pwq_set_max_active(struct pool_workqueue *pwq, int max_active) 32929f4bd4cdSLai Jiangshan { 3293112202d9STejun Heo pwq->max_active = max_active; 32949f4bd4cdSLai Jiangshan 3295112202d9STejun Heo while (!list_empty(&pwq->delayed_works) && 3296112202d9STejun Heo pwq->nr_active < pwq->max_active) 3297112202d9STejun Heo pwq_activate_first_delayed(pwq); 32989f4bd4cdSLai Jiangshan } 32999f4bd4cdSLai Jiangshan 33009f4bd4cdSLai Jiangshan /** 3301dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 3302dcd989cbSTejun Heo * @wq: target workqueue 3303dcd989cbSTejun Heo * @max_active: new max_active value. 3304dcd989cbSTejun Heo * 3305dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 3306dcd989cbSTejun Heo * 3307dcd989cbSTejun Heo * CONTEXT: 3308dcd989cbSTejun Heo * Don't call from IRQ context. 3309dcd989cbSTejun Heo */ 3310dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 3311dcd989cbSTejun Heo { 3312dcd989cbSTejun Heo unsigned int cpu; 3313dcd989cbSTejun Heo 3314f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 3315dcd989cbSTejun Heo 3316e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3317dcd989cbSTejun Heo 3318dcd989cbSTejun Heo wq->saved_max_active = max_active; 3319dcd989cbSTejun Heo 3320112202d9STejun Heo for_each_pwq_cpu(cpu, wq) { 3321112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 3322112202d9STejun Heo struct worker_pool *pool = pwq->pool; 3323dcd989cbSTejun Heo 3324e98d5b16STejun Heo spin_lock(&pool->lock); 3325dcd989cbSTejun Heo 332658a69cb4STejun Heo if (!(wq->flags & WQ_FREEZABLE) || 332735b6bb63STejun Heo !(pool->flags & POOL_FREEZING)) 3328112202d9STejun Heo pwq_set_max_active(pwq, max_active); 3329dcd989cbSTejun Heo 3330e98d5b16STejun Heo spin_unlock(&pool->lock); 3331dcd989cbSTejun Heo } 3332dcd989cbSTejun Heo 3333e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 3334dcd989cbSTejun Heo } 3335dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 3336dcd989cbSTejun Heo 3337dcd989cbSTejun Heo /** 3338dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 3339dcd989cbSTejun Heo * @cpu: CPU in question 3340dcd989cbSTejun Heo * @wq: target workqueue 3341dcd989cbSTejun Heo * 3342dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 3343dcd989cbSTejun Heo * no synchronization around this function and the test result is 3344dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3345dcd989cbSTejun Heo * 3346dcd989cbSTejun Heo * RETURNS: 3347dcd989cbSTejun Heo * %true if congested, %false otherwise. 3348dcd989cbSTejun Heo */ 3349dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 3350dcd989cbSTejun Heo { 3351112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 3352dcd989cbSTejun Heo 3353112202d9STejun Heo return !list_empty(&pwq->delayed_works); 3354dcd989cbSTejun Heo } 3355dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 3356dcd989cbSTejun Heo 3357dcd989cbSTejun Heo /** 3358dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 3359dcd989cbSTejun Heo * @work: the work to be tested 3360dcd989cbSTejun Heo * 3361dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 3362dcd989cbSTejun Heo * synchronization around this function and the test result is 3363dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3364dcd989cbSTejun Heo * 3365dcd989cbSTejun Heo * RETURNS: 3366dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 3367dcd989cbSTejun Heo */ 3368dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 3369dcd989cbSTejun Heo { 3370c9e7cf27STejun Heo struct worker_pool *pool = get_work_pool(work); 3371dcd989cbSTejun Heo unsigned long flags; 3372dcd989cbSTejun Heo unsigned int ret = 0; 3373dcd989cbSTejun Heo 3374dcd989cbSTejun Heo if (work_pending(work)) 3375dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 3376038366c5SLai Jiangshan 3377038366c5SLai Jiangshan if (pool) { 3378038366c5SLai Jiangshan spin_lock_irqsave(&pool->lock, flags); 3379c9e7cf27STejun Heo if (find_worker_executing_work(pool, work)) 3380dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 3381d565ed63STejun Heo spin_unlock_irqrestore(&pool->lock, flags); 3382038366c5SLai Jiangshan } 3383dcd989cbSTejun Heo 3384dcd989cbSTejun Heo return ret; 3385dcd989cbSTejun Heo } 3386dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 3387dcd989cbSTejun Heo 3388db7bccf4STejun Heo /* 3389db7bccf4STejun Heo * CPU hotplug. 3390db7bccf4STejun Heo * 3391e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 3392112202d9STejun Heo * are a lot of assumptions on strong associations among work, pwq and 3393706026c2STejun Heo * pool which make migrating pending and scheduled works very 3394e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 339594cf58bbSTejun Heo * worker pools serve mix of short, long and very long running works making 3396e22bee78STejun Heo * blocked draining impractical. 3397e22bee78STejun Heo * 339824647570STejun Heo * This is solved by allowing the pools to be disassociated from the CPU 3399628c78e7STejun Heo * running as an unbound one and allowing it to be reattached later if the 3400628c78e7STejun Heo * cpu comes back online. 3401db7bccf4STejun Heo */ 3402db7bccf4STejun Heo 3403706026c2STejun Heo static void wq_unbind_fn(struct work_struct *work) 3404db7bccf4STejun Heo { 340538db41d9STejun Heo int cpu = smp_processor_id(); 34064ce62e9eSTejun Heo struct worker_pool *pool; 3407db7bccf4STejun Heo struct worker *worker; 3408db7bccf4STejun Heo int i; 3409db7bccf4STejun Heo 341038db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 34116183c009STejun Heo WARN_ON_ONCE(cpu != smp_processor_id()); 3412db7bccf4STejun Heo 341394cf58bbSTejun Heo mutex_lock(&pool->assoc_mutex); 341494cf58bbSTejun Heo spin_lock_irq(&pool->lock); 3415e22bee78STejun Heo 3416f2d5a0eeSTejun Heo /* 341794cf58bbSTejun Heo * We've claimed all manager positions. Make all workers 341894cf58bbSTejun Heo * unbound and set DISASSOCIATED. Before this, all workers 341994cf58bbSTejun Heo * except for the ones which are still executing works from 342094cf58bbSTejun Heo * before the last CPU down must be on the cpu. After 342194cf58bbSTejun Heo * this, they may become diasporas. 3422f2d5a0eeSTejun Heo */ 34234ce62e9eSTejun Heo list_for_each_entry(worker, &pool->idle_list, entry) 3424403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 3425db7bccf4STejun Heo 3426b67bfe0dSSasha Levin for_each_busy_worker(worker, i, pool) 3427403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 3428db7bccf4STejun Heo 342924647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 3430f2d5a0eeSTejun Heo 343194cf58bbSTejun Heo spin_unlock_irq(&pool->lock); 343294cf58bbSTejun Heo mutex_unlock(&pool->assoc_mutex); 343394cf58bbSTejun Heo } 3434e22bee78STejun Heo 3435e22bee78STejun Heo /* 3436628c78e7STejun Heo * Call schedule() so that we cross rq->lock and thus can guarantee 3437628c78e7STejun Heo * sched callbacks see the %WORKER_UNBOUND flag. This is necessary 3438628c78e7STejun Heo * as scheduler callbacks may be invoked from other cpus. 3439628c78e7STejun Heo */ 3440628c78e7STejun Heo schedule(); 3441628c78e7STejun Heo 3442628c78e7STejun Heo /* 3443628c78e7STejun Heo * Sched callbacks are disabled now. Zap nr_running. After this, 3444628c78e7STejun Heo * nr_running stays zero and need_more_worker() and keep_working() 344538db41d9STejun Heo * are always true as long as the worklist is not empty. Pools on 344638db41d9STejun Heo * @cpu now behave as unbound (in terms of concurrency management) 344738db41d9STejun Heo * pools which are served by workers tied to the CPU. 3448628c78e7STejun Heo * 3449628c78e7STejun Heo * On return from this function, the current worker would trigger 3450628c78e7STejun Heo * unbound chain execution of pending work items if other workers 3451628c78e7STejun Heo * didn't already. 3452e22bee78STejun Heo */ 345338db41d9STejun Heo for_each_std_worker_pool(pool, cpu) 3454e19e397aSTejun Heo atomic_set(&pool->nr_running, 0); 3455db7bccf4STejun Heo } 3456db7bccf4STejun Heo 34578db25e78STejun Heo /* 34588db25e78STejun Heo * Workqueues should be brought up before normal priority CPU notifiers. 34598db25e78STejun Heo * This will be registered high priority CPU notifier. 34608db25e78STejun Heo */ 34619fdf9b73SLai Jiangshan static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb, 34621da177e4SLinus Torvalds unsigned long action, 34631da177e4SLinus Torvalds void *hcpu) 34641da177e4SLinus Torvalds { 34653af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 34664ce62e9eSTejun Heo struct worker_pool *pool; 34671da177e4SLinus Torvalds 34688db25e78STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 34693af24433SOleg Nesterov case CPU_UP_PREPARE: 347038db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 34713ce63377STejun Heo struct worker *worker; 34723ce63377STejun Heo 34733ce63377STejun Heo if (pool->nr_workers) 34743ce63377STejun Heo continue; 34753ce63377STejun Heo 34763ce63377STejun Heo worker = create_worker(pool); 34773ce63377STejun Heo if (!worker) 34783ce63377STejun Heo return NOTIFY_BAD; 34793ce63377STejun Heo 3480d565ed63STejun Heo spin_lock_irq(&pool->lock); 34813ce63377STejun Heo start_worker(worker); 3482d565ed63STejun Heo spin_unlock_irq(&pool->lock); 34833af24433SOleg Nesterov } 34841da177e4SLinus Torvalds break; 34851da177e4SLinus Torvalds 348665758202STejun Heo case CPU_DOWN_FAILED: 348765758202STejun Heo case CPU_ONLINE: 348838db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 348994cf58bbSTejun Heo mutex_lock(&pool->assoc_mutex); 349094cf58bbSTejun Heo spin_lock_irq(&pool->lock); 349194cf58bbSTejun Heo 349224647570STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 349394cf58bbSTejun Heo rebind_workers(pool); 349494cf58bbSTejun Heo 349594cf58bbSTejun Heo spin_unlock_irq(&pool->lock); 349694cf58bbSTejun Heo mutex_unlock(&pool->assoc_mutex); 349794cf58bbSTejun Heo } 34988db25e78STejun Heo break; 349965758202STejun Heo } 350065758202STejun Heo return NOTIFY_OK; 350165758202STejun Heo } 350265758202STejun Heo 350365758202STejun Heo /* 350465758202STejun Heo * Workqueues should be brought down after normal priority CPU notifiers. 350565758202STejun Heo * This will be registered as low priority CPU notifier. 350665758202STejun Heo */ 35079fdf9b73SLai Jiangshan static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb, 350865758202STejun Heo unsigned long action, 350965758202STejun Heo void *hcpu) 351065758202STejun Heo { 35118db25e78STejun Heo unsigned int cpu = (unsigned long)hcpu; 35128db25e78STejun Heo struct work_struct unbind_work; 35138db25e78STejun Heo 351465758202STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 351565758202STejun Heo case CPU_DOWN_PREPARE: 35168db25e78STejun Heo /* unbinding should happen on the local CPU */ 3517706026c2STejun Heo INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn); 35187635d2fdSJoonsoo Kim queue_work_on(cpu, system_highpri_wq, &unbind_work); 35198db25e78STejun Heo flush_work(&unbind_work); 35208db25e78STejun Heo break; 352165758202STejun Heo } 352265758202STejun Heo return NOTIFY_OK; 352365758202STejun Heo } 352465758202STejun Heo 35252d3854a3SRusty Russell #ifdef CONFIG_SMP 35268ccad40dSRusty Russell 35272d3854a3SRusty Russell struct work_for_cpu { 3528ed48ece2STejun Heo struct work_struct work; 35292d3854a3SRusty Russell long (*fn)(void *); 35302d3854a3SRusty Russell void *arg; 35312d3854a3SRusty Russell long ret; 35322d3854a3SRusty Russell }; 35332d3854a3SRusty Russell 3534ed48ece2STejun Heo static void work_for_cpu_fn(struct work_struct *work) 35352d3854a3SRusty Russell { 3536ed48ece2STejun Heo struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); 3537ed48ece2STejun Heo 35382d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 35392d3854a3SRusty Russell } 35402d3854a3SRusty Russell 35412d3854a3SRusty Russell /** 35422d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 35432d3854a3SRusty Russell * @cpu: the cpu to run on 35442d3854a3SRusty Russell * @fn: the function to run 35452d3854a3SRusty Russell * @arg: the function arg 35462d3854a3SRusty Russell * 354731ad9081SRusty Russell * This will return the value @fn returns. 354831ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 35496b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 35502d3854a3SRusty Russell */ 35512d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 35522d3854a3SRusty Russell { 3553ed48ece2STejun Heo struct work_for_cpu wfc = { .fn = fn, .arg = arg }; 35542d3854a3SRusty Russell 3555ed48ece2STejun Heo INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); 3556ed48ece2STejun Heo schedule_work_on(cpu, &wfc.work); 3557ed48ece2STejun Heo flush_work(&wfc.work); 35582d3854a3SRusty Russell return wfc.ret; 35592d3854a3SRusty Russell } 35602d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 35612d3854a3SRusty Russell #endif /* CONFIG_SMP */ 35622d3854a3SRusty Russell 3563a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3564e7577c50SRusty Russell 3565a0a1a5fdSTejun Heo /** 3566a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3567a0a1a5fdSTejun Heo * 356858a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 356958a69cb4STejun Heo * workqueues will queue new works to their frozen_works list instead of 3570706026c2STejun Heo * pool->worklist. 3571a0a1a5fdSTejun Heo * 3572a0a1a5fdSTejun Heo * CONTEXT: 3573d565ed63STejun Heo * Grabs and releases workqueue_lock and pool->lock's. 3574a0a1a5fdSTejun Heo */ 3575a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3576a0a1a5fdSTejun Heo { 3577a0a1a5fdSTejun Heo unsigned int cpu; 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 3584706026c2STejun Heo for_each_wq_cpu(cpu) { 358535b6bb63STejun Heo struct worker_pool *pool; 3586bdbc5dd7STejun Heo struct workqueue_struct *wq; 35878b03ae3cSTejun Heo 358838db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 3589e98d5b16STejun Heo spin_lock(&pool->lock); 3590d565ed63STejun Heo 359135b6bb63STejun Heo WARN_ON_ONCE(pool->flags & POOL_FREEZING); 359235b6bb63STejun Heo pool->flags |= POOL_FREEZING; 3593db7bccf4STejun Heo 3594a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3595112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 3596a0a1a5fdSTejun Heo 3597112202d9STejun Heo if (pwq && pwq->pool == pool && 3598a1056305STejun Heo (wq->flags & WQ_FREEZABLE)) 3599112202d9STejun Heo pwq->max_active = 0; 36001da177e4SLinus Torvalds } 36018b03ae3cSTejun Heo 3602e98d5b16STejun Heo spin_unlock(&pool->lock); 3603a1056305STejun Heo } 3604a0a1a5fdSTejun Heo } 3605a0a1a5fdSTejun Heo 3606e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 3607a0a1a5fdSTejun Heo } 3608a0a1a5fdSTejun Heo 3609a0a1a5fdSTejun Heo /** 361058a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 3611a0a1a5fdSTejun Heo * 3612a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3613a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3614a0a1a5fdSTejun Heo * 3615a0a1a5fdSTejun Heo * CONTEXT: 3616a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3617a0a1a5fdSTejun Heo * 3618a0a1a5fdSTejun Heo * RETURNS: 361958a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 362058a69cb4STejun Heo * is complete. 3621a0a1a5fdSTejun Heo */ 3622a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3623a0a1a5fdSTejun Heo { 3624a0a1a5fdSTejun Heo unsigned int cpu; 3625a0a1a5fdSTejun Heo bool busy = false; 3626a0a1a5fdSTejun Heo 3627e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3628a0a1a5fdSTejun Heo 36296183c009STejun Heo WARN_ON_ONCE(!workqueue_freezing); 3630a0a1a5fdSTejun Heo 3631706026c2STejun Heo for_each_wq_cpu(cpu) { 3632bdbc5dd7STejun Heo struct workqueue_struct *wq; 3633a0a1a5fdSTejun Heo /* 3634a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3635a0a1a5fdSTejun Heo * to peek without lock. 3636a0a1a5fdSTejun Heo */ 3637a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3638112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 3639a0a1a5fdSTejun Heo 3640112202d9STejun Heo if (!pwq || !(wq->flags & WQ_FREEZABLE)) 3641a0a1a5fdSTejun Heo continue; 3642a0a1a5fdSTejun Heo 36436183c009STejun Heo WARN_ON_ONCE(pwq->nr_active < 0); 3644112202d9STejun Heo if (pwq->nr_active) { 3645a0a1a5fdSTejun Heo busy = true; 3646a0a1a5fdSTejun Heo goto out_unlock; 3647a0a1a5fdSTejun Heo } 3648a0a1a5fdSTejun Heo } 3649a0a1a5fdSTejun Heo } 3650a0a1a5fdSTejun Heo out_unlock: 3651e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 3652a0a1a5fdSTejun Heo return busy; 3653a0a1a5fdSTejun Heo } 3654a0a1a5fdSTejun Heo 3655a0a1a5fdSTejun Heo /** 3656a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3657a0a1a5fdSTejun Heo * 3658a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 3659706026c2STejun Heo * frozen works are transferred to their respective pool worklists. 3660a0a1a5fdSTejun Heo * 3661a0a1a5fdSTejun Heo * CONTEXT: 3662d565ed63STejun Heo * Grabs and releases workqueue_lock and pool->lock's. 3663a0a1a5fdSTejun Heo */ 3664a0a1a5fdSTejun Heo void thaw_workqueues(void) 3665a0a1a5fdSTejun Heo { 3666a0a1a5fdSTejun Heo unsigned int cpu; 3667a0a1a5fdSTejun Heo 3668e98d5b16STejun Heo spin_lock_irq(&workqueue_lock); 3669a0a1a5fdSTejun Heo 3670a0a1a5fdSTejun Heo if (!workqueue_freezing) 3671a0a1a5fdSTejun Heo goto out_unlock; 3672a0a1a5fdSTejun Heo 3673706026c2STejun Heo for_each_wq_cpu(cpu) { 36744ce62e9eSTejun Heo struct worker_pool *pool; 3675bdbc5dd7STejun Heo struct workqueue_struct *wq; 36768b03ae3cSTejun Heo 367738db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 3678e98d5b16STejun Heo spin_lock(&pool->lock); 3679d565ed63STejun Heo 368035b6bb63STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); 368135b6bb63STejun Heo pool->flags &= ~POOL_FREEZING; 3682db7bccf4STejun Heo 3683a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3684112202d9STejun Heo struct pool_workqueue *pwq = get_pwq(cpu, wq); 3685a0a1a5fdSTejun Heo 3686112202d9STejun Heo if (!pwq || pwq->pool != pool || 3687a1056305STejun Heo !(wq->flags & WQ_FREEZABLE)) 3688a0a1a5fdSTejun Heo continue; 3689a0a1a5fdSTejun Heo 3690a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 3691112202d9STejun Heo pwq_set_max_active(pwq, wq->saved_max_active); 3692a0a1a5fdSTejun Heo } 36938b03ae3cSTejun Heo 36944ce62e9eSTejun Heo wake_up_worker(pool); 3695a1056305STejun Heo 3696e98d5b16STejun Heo spin_unlock(&pool->lock); 3697d565ed63STejun Heo } 3698a0a1a5fdSTejun Heo } 3699a0a1a5fdSTejun Heo 3700a0a1a5fdSTejun Heo workqueue_freezing = false; 3701a0a1a5fdSTejun Heo out_unlock: 3702e98d5b16STejun Heo spin_unlock_irq(&workqueue_lock); 3703a0a1a5fdSTejun Heo } 3704a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3705a0a1a5fdSTejun Heo 37066ee0578bSSuresh Siddha static int __init init_workqueues(void) 37071da177e4SLinus Torvalds { 3708c34056a3STejun Heo unsigned int cpu; 3709c34056a3STejun Heo 37107c3eed5cSTejun Heo /* make sure we have enough bits for OFFQ pool ID */ 37117c3eed5cSTejun Heo BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) < 37126be19588SLai Jiangshan WORK_CPU_END * NR_STD_WORKER_POOLS); 3713b5490077STejun Heo 3714e904e6c2STejun Heo WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); 3715e904e6c2STejun Heo 3716e904e6c2STejun Heo pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); 3717e904e6c2STejun Heo 371865758202STejun Heo cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); 3719a5b4e57dSLai Jiangshan hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); 37208b03ae3cSTejun Heo 3721706026c2STejun Heo /* initialize CPU pools */ 3722706026c2STejun Heo for_each_wq_cpu(cpu) { 37234ce62e9eSTejun Heo struct worker_pool *pool; 37248b03ae3cSTejun Heo 372538db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 3726d565ed63STejun Heo spin_lock_init(&pool->lock); 3727ec22ca5eSTejun Heo pool->cpu = cpu; 372824647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 37294ce62e9eSTejun Heo INIT_LIST_HEAD(&pool->worklist); 37304ce62e9eSTejun Heo INIT_LIST_HEAD(&pool->idle_list); 3731c9e7cf27STejun Heo hash_init(pool->busy_hash); 3732e22bee78STejun Heo 37334ce62e9eSTejun Heo init_timer_deferrable(&pool->idle_timer); 37344ce62e9eSTejun Heo pool->idle_timer.function = idle_worker_timeout; 37354ce62e9eSTejun Heo pool->idle_timer.data = (unsigned long)pool; 3736e22bee78STejun Heo 3737706026c2STejun Heo setup_timer(&pool->mayday_timer, pool_mayday_timeout, 37384ce62e9eSTejun Heo (unsigned long)pool); 37394ce62e9eSTejun Heo 3740b2eb83d1SLai Jiangshan mutex_init(&pool->assoc_mutex); 37414ce62e9eSTejun Heo ida_init(&pool->worker_ida); 37429daf9e67STejun Heo 37439daf9e67STejun Heo /* alloc pool ID */ 37449daf9e67STejun Heo BUG_ON(worker_pool_assign_id(pool)); 37454ce62e9eSTejun Heo } 37468b03ae3cSTejun Heo } 37478b03ae3cSTejun Heo 3748e22bee78STejun Heo /* create the initial worker */ 3749706026c2STejun Heo for_each_online_wq_cpu(cpu) { 37504ce62e9eSTejun Heo struct worker_pool *pool; 3751e22bee78STejun Heo 375238db41d9STejun Heo for_each_std_worker_pool(pool, cpu) { 37534ce62e9eSTejun Heo struct worker *worker; 37544ce62e9eSTejun Heo 375524647570STejun Heo if (cpu != WORK_CPU_UNBOUND) 375624647570STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 375724647570STejun Heo 3758bc2ae0f5STejun Heo worker = create_worker(pool); 3759e22bee78STejun Heo BUG_ON(!worker); 3760d565ed63STejun Heo spin_lock_irq(&pool->lock); 3761e22bee78STejun Heo start_worker(worker); 3762d565ed63STejun Heo spin_unlock_irq(&pool->lock); 3763e22bee78STejun Heo } 37644ce62e9eSTejun Heo } 3765e22bee78STejun Heo 3766d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 37671aabe902SJoonsoo Kim system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 3768d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3769f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3770f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 377124d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 377224d51addSTejun Heo WQ_FREEZABLE, 0); 37731aabe902SJoonsoo Kim BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 3774ae930e0fSTejun Heo !system_unbound_wq || !system_freezable_wq); 37756ee0578bSSuresh Siddha return 0; 37761da177e4SLinus Torvalds } 37776ee0578bSSuresh Siddha early_initcall(init_workqueues); 3778