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 * 1118b03ae3cSTejun Heo * L: gcwq->lock protected. Access with gcwq->lock held. 1124690c4abSTejun Heo * 113e22bee78STejun Heo * X: During normal operation, modification requires gcwq->lock and 114e22bee78STejun Heo * should be done only from local cpu. Either disabling preemption 115e22bee78STejun Heo * on local cpu or grabbing gcwq->lock is enough for read access. 11624647570STejun Heo * If 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 { 126bd7bdd43STejun Heo struct global_cwq *gcwq; /* I: the owning gcwq */ 1279daf9e67STejun Heo int id; /* I: pool ID */ 12811ebea50STejun Heo unsigned int flags; /* X: flags */ 129bd7bdd43STejun Heo 130bd7bdd43STejun Heo struct list_head worklist; /* L: list of pending works */ 131bd7bdd43STejun Heo int nr_workers; /* L: total number of workers */ 132ea1abd61SLai Jiangshan 133ea1abd61SLai Jiangshan /* nr_idle includes the ones off idle_list for rebinding */ 134bd7bdd43STejun Heo int nr_idle; /* L: currently idle ones */ 135bd7bdd43STejun Heo 136bd7bdd43STejun Heo struct list_head idle_list; /* X: list of idle workers */ 137bd7bdd43STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 138bd7bdd43STejun Heo struct timer_list mayday_timer; /* L: SOS timer for workers */ 139bd7bdd43STejun Heo 14024647570STejun Heo struct mutex assoc_mutex; /* protect POOL_DISASSOCIATED */ 141bd7bdd43STejun Heo struct ida worker_ida; /* L: for worker IDs */ 142bd7bdd43STejun Heo }; 143bd7bdd43STejun Heo 1444690c4abSTejun Heo /* 145e22bee78STejun Heo * Global per-cpu workqueue. There's one and only one for each cpu 146e22bee78STejun Heo * and all works are queued and processed here regardless of their 147e22bee78STejun Heo * target workqueues. 1488b03ae3cSTejun Heo */ 1498b03ae3cSTejun Heo struct global_cwq { 1508b03ae3cSTejun Heo spinlock_t lock; /* the gcwq lock */ 1518b03ae3cSTejun Heo unsigned int cpu; /* I: the associated cpu */ 152c8e55f36STejun Heo 153bd7bdd43STejun Heo /* workers are chained either in busy_hash or pool idle_list */ 15442f8570fSSasha Levin DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); 155c8e55f36STejun Heo /* L: hash of busy workers */ 156c8e55f36STejun Heo 157e34cdddbSTejun Heo struct worker_pool pools[NR_STD_WORKER_POOLS]; 158330dad5bSJoonsoo Kim /* normal and highpri pools */ 1598b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1608b03ae3cSTejun Heo 1618b03ae3cSTejun Heo /* 162502ca9d8STejun Heo * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of 1630f900049STejun Heo * work_struct->data are used for flags and thus cwqs need to be 1640f900049STejun Heo * aligned at two's power of the number of flag bits. 1651da177e4SLinus Torvalds */ 1661da177e4SLinus Torvalds struct cpu_workqueue_struct { 167bd7bdd43STejun Heo struct worker_pool *pool; /* I: the associated pool */ 1684690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 16973f53c4aSTejun Heo int work_color; /* L: current color */ 17073f53c4aSTejun Heo int flush_color; /* L: flushing color */ 17173f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 17273f53c4aSTejun Heo /* L: nr of in_flight works */ 1731e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 174a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 1751e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 1760f900049STejun Heo }; 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds /* 17973f53c4aSTejun Heo * Structure used to wait for workqueue flush. 18073f53c4aSTejun Heo */ 18173f53c4aSTejun Heo struct wq_flusher { 18273f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 18373f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 18473f53c4aSTejun Heo struct completion done; /* flush completion */ 18573f53c4aSTejun Heo }; 1861da177e4SLinus Torvalds 18773f53c4aSTejun Heo /* 188f2e005aaSTejun Heo * All cpumasks are assumed to be always set on UP and thus can't be 189f2e005aaSTejun Heo * used to determine whether there's something to be done. 190f2e005aaSTejun Heo */ 191f2e005aaSTejun Heo #ifdef CONFIG_SMP 192f2e005aaSTejun Heo typedef cpumask_var_t mayday_mask_t; 193f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) \ 194f2e005aaSTejun Heo cpumask_test_and_set_cpu((cpu), (mask)) 195f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) 196f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) 1979c37547aSTejun Heo #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) 198f2e005aaSTejun Heo #define free_mayday_mask(mask) free_cpumask_var((mask)) 199f2e005aaSTejun Heo #else 200f2e005aaSTejun Heo typedef unsigned long mayday_mask_t; 201f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) 202f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) 203f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) 204f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) true 205f2e005aaSTejun Heo #define free_mayday_mask(mask) do { } while (0) 206f2e005aaSTejun Heo #endif 2071da177e4SLinus Torvalds 2081da177e4SLinus Torvalds /* 2091da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 2101da177e4SLinus Torvalds * per-CPU workqueues: 2111da177e4SLinus Torvalds */ 2121da177e4SLinus Torvalds struct workqueue_struct { 2139c5a2ba7STejun Heo unsigned int flags; /* W: WQ_* flags */ 214bdbc5dd7STejun Heo union { 215bdbc5dd7STejun Heo struct cpu_workqueue_struct __percpu *pcpu; 216bdbc5dd7STejun Heo struct cpu_workqueue_struct *single; 217bdbc5dd7STejun Heo unsigned long v; 218bdbc5dd7STejun Heo } cpu_wq; /* I: cwq's */ 2194690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 22073f53c4aSTejun Heo 22173f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 22273f53c4aSTejun Heo int work_color; /* F: current work color */ 22373f53c4aSTejun Heo int flush_color; /* F: current flush color */ 22473f53c4aSTejun Heo atomic_t nr_cwqs_to_flush; /* flush in progress */ 22573f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 22673f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 22773f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 22873f53c4aSTejun Heo 229f2e005aaSTejun Heo mayday_mask_t mayday_mask; /* cpus requesting rescue */ 230e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 231e22bee78STejun Heo 2329c5a2ba7STejun Heo int nr_drainers; /* W: drain in progress */ 233dcd989cbSTejun Heo int saved_max_active; /* W: saved cwq max_active */ 2344e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2354e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2364e6045f1SJohannes Berg #endif 237b196be89STejun Heo char name[]; /* I: workqueue name */ 2381da177e4SLinus Torvalds }; 2391da177e4SLinus Torvalds 240d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 241d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 242044c782cSValentin Ilie struct workqueue_struct *system_highpri_wq __read_mostly; 2431aabe902SJoonsoo Kim EXPORT_SYMBOL_GPL(system_highpri_wq); 244044c782cSValentin Ilie struct workqueue_struct *system_long_wq __read_mostly; 245d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 246044c782cSValentin Ilie struct workqueue_struct *system_unbound_wq __read_mostly; 247f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 248044c782cSValentin Ilie struct workqueue_struct *system_freezable_wq __read_mostly; 24924d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 250d320c038STejun Heo 25197bd2347STejun Heo #define CREATE_TRACE_POINTS 25297bd2347STejun Heo #include <trace/events/workqueue.h> 25397bd2347STejun Heo 2544ce62e9eSTejun Heo #define for_each_worker_pool(pool, gcwq) \ 2553270476aSTejun Heo for ((pool) = &(gcwq)->pools[0]; \ 256e34cdddbSTejun Heo (pool) < &(gcwq)->pools[NR_STD_WORKER_POOLS]; (pool)++) 2574ce62e9eSTejun Heo 258db7bccf4STejun Heo #define for_each_busy_worker(worker, i, pos, gcwq) \ 25942f8570fSSasha Levin hash_for_each(gcwq->busy_hash, i, pos, worker, hentry) 260db7bccf4STejun Heo 261f3421797STejun Heo static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, 262f3421797STejun Heo unsigned int sw) 263f3421797STejun Heo { 264f3421797STejun Heo if (cpu < nr_cpu_ids) { 265f3421797STejun Heo if (sw & 1) { 266f3421797STejun Heo cpu = cpumask_next(cpu, mask); 267f3421797STejun Heo if (cpu < nr_cpu_ids) 268f3421797STejun Heo return cpu; 269f3421797STejun Heo } 270f3421797STejun Heo if (sw & 2) 271f3421797STejun Heo return WORK_CPU_UNBOUND; 272f3421797STejun Heo } 273f3421797STejun Heo return WORK_CPU_NONE; 274f3421797STejun Heo } 275f3421797STejun Heo 276f3421797STejun Heo static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, 277f3421797STejun Heo struct workqueue_struct *wq) 278f3421797STejun Heo { 279f3421797STejun Heo return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); 280f3421797STejun Heo } 281f3421797STejun Heo 28209884951STejun Heo /* 28309884951STejun Heo * CPU iterators 28409884951STejun Heo * 28509884951STejun Heo * An extra gcwq is defined for an invalid cpu number 28609884951STejun Heo * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any 28709884951STejun Heo * specific CPU. The following iterators are similar to 28809884951STejun Heo * for_each_*_cpu() iterators but also considers the unbound gcwq. 28909884951STejun Heo * 29009884951STejun Heo * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND 29109884951STejun Heo * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND 29209884951STejun Heo * for_each_cwq_cpu() : possible CPUs for bound workqueues, 29309884951STejun Heo * WORK_CPU_UNBOUND for unbound workqueues 29409884951STejun Heo */ 295f3421797STejun Heo #define for_each_gcwq_cpu(cpu) \ 296f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ 297f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 298f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) 299f3421797STejun Heo 300f3421797STejun Heo #define for_each_online_gcwq_cpu(cpu) \ 301f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ 302f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 303f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) 304f3421797STejun Heo 305f3421797STejun Heo #define for_each_cwq_cpu(cpu, wq) \ 306f3421797STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ 307f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 308f3421797STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) 309f3421797STejun Heo 310dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 311dc186ad7SThomas Gleixner 312dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 313dc186ad7SThomas Gleixner 31499777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 31599777288SStanislaw Gruszka { 31699777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 31799777288SStanislaw Gruszka } 31899777288SStanislaw Gruszka 319dc186ad7SThomas Gleixner /* 320dc186ad7SThomas Gleixner * fixup_init is called when: 321dc186ad7SThomas Gleixner * - an active object is initialized 322dc186ad7SThomas Gleixner */ 323dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 324dc186ad7SThomas Gleixner { 325dc186ad7SThomas Gleixner struct work_struct *work = addr; 326dc186ad7SThomas Gleixner 327dc186ad7SThomas Gleixner switch (state) { 328dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 329dc186ad7SThomas Gleixner cancel_work_sync(work); 330dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 331dc186ad7SThomas Gleixner return 1; 332dc186ad7SThomas Gleixner default: 333dc186ad7SThomas Gleixner return 0; 334dc186ad7SThomas Gleixner } 335dc186ad7SThomas Gleixner } 336dc186ad7SThomas Gleixner 337dc186ad7SThomas Gleixner /* 338dc186ad7SThomas Gleixner * fixup_activate is called when: 339dc186ad7SThomas Gleixner * - an active object is activated 340dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 341dc186ad7SThomas Gleixner */ 342dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 343dc186ad7SThomas Gleixner { 344dc186ad7SThomas Gleixner struct work_struct *work = addr; 345dc186ad7SThomas Gleixner 346dc186ad7SThomas Gleixner switch (state) { 347dc186ad7SThomas Gleixner 348dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 349dc186ad7SThomas Gleixner /* 350dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 351dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 352dc186ad7SThomas Gleixner * is tracked in the object tracker. 353dc186ad7SThomas Gleixner */ 35422df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 355dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 356dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 357dc186ad7SThomas Gleixner return 0; 358dc186ad7SThomas Gleixner } 359dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 360dc186ad7SThomas Gleixner return 0; 361dc186ad7SThomas Gleixner 362dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 363dc186ad7SThomas Gleixner WARN_ON(1); 364dc186ad7SThomas Gleixner 365dc186ad7SThomas Gleixner default: 366dc186ad7SThomas Gleixner return 0; 367dc186ad7SThomas Gleixner } 368dc186ad7SThomas Gleixner } 369dc186ad7SThomas Gleixner 370dc186ad7SThomas Gleixner /* 371dc186ad7SThomas Gleixner * fixup_free is called when: 372dc186ad7SThomas Gleixner * - an active object is freed 373dc186ad7SThomas Gleixner */ 374dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 375dc186ad7SThomas Gleixner { 376dc186ad7SThomas Gleixner struct work_struct *work = addr; 377dc186ad7SThomas Gleixner 378dc186ad7SThomas Gleixner switch (state) { 379dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 380dc186ad7SThomas Gleixner cancel_work_sync(work); 381dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 382dc186ad7SThomas Gleixner return 1; 383dc186ad7SThomas Gleixner default: 384dc186ad7SThomas Gleixner return 0; 385dc186ad7SThomas Gleixner } 386dc186ad7SThomas Gleixner } 387dc186ad7SThomas Gleixner 388dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 389dc186ad7SThomas Gleixner .name = "work_struct", 39099777288SStanislaw Gruszka .debug_hint = work_debug_hint, 391dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 392dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 393dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 394dc186ad7SThomas Gleixner }; 395dc186ad7SThomas Gleixner 396dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 397dc186ad7SThomas Gleixner { 398dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 399dc186ad7SThomas Gleixner } 400dc186ad7SThomas Gleixner 401dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 402dc186ad7SThomas Gleixner { 403dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 404dc186ad7SThomas Gleixner } 405dc186ad7SThomas Gleixner 406dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 407dc186ad7SThomas Gleixner { 408dc186ad7SThomas Gleixner if (onstack) 409dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 410dc186ad7SThomas Gleixner else 411dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 412dc186ad7SThomas Gleixner } 413dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 414dc186ad7SThomas Gleixner 415dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 416dc186ad7SThomas Gleixner { 417dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 418dc186ad7SThomas Gleixner } 419dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 420dc186ad7SThomas Gleixner 421dc186ad7SThomas Gleixner #else 422dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 423dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 424dc186ad7SThomas Gleixner #endif 425dc186ad7SThomas Gleixner 42695402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 42795402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 4281da177e4SLinus Torvalds static LIST_HEAD(workqueues); 429a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 4301da177e4SLinus Torvalds 43114441960SOleg Nesterov /* 432e22bee78STejun Heo * The almighty global cpu workqueues. nr_running is the only field 433e22bee78STejun Heo * which is expected to be used frequently by other cpus via 434e22bee78STejun Heo * try_to_wake_up(). Put it in a separate cacheline. 43514441960SOleg Nesterov */ 4368b03ae3cSTejun Heo static DEFINE_PER_CPU(struct global_cwq, global_cwq); 437e34cdddbSTejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_STD_WORKER_POOLS]); 438f756d5e2SNathan Lynch 439f3421797STejun Heo /* 44024647570STejun Heo * Global cpu workqueue and nr_running counter for unbound gcwq. The pools 44124647570STejun Heo * for online CPUs have POOL_DISASSOCIATED set, and all their workers have 44224647570STejun Heo * WORKER_UNBOUND set. 443f3421797STejun Heo */ 444f3421797STejun Heo static struct global_cwq unbound_global_cwq; 445e34cdddbSTejun Heo static atomic_t unbound_pool_nr_running[NR_STD_WORKER_POOLS] = { 446e34cdddbSTejun Heo [0 ... NR_STD_WORKER_POOLS - 1] = ATOMIC_INIT(0), /* always 0 */ 4474ce62e9eSTejun Heo }; 448f3421797STejun Heo 4499daf9e67STejun Heo /* idr of all pools */ 4509daf9e67STejun Heo static DEFINE_MUTEX(worker_pool_idr_mutex); 4519daf9e67STejun Heo static DEFINE_IDR(worker_pool_idr); 4529daf9e67STejun Heo 453c34056a3STejun Heo static int worker_thread(void *__worker); 454e2905b29STejun Heo static unsigned int work_cpu(struct work_struct *work); 4551da177e4SLinus Torvalds 456e34cdddbSTejun Heo static int std_worker_pool_pri(struct worker_pool *pool) 4573270476aSTejun Heo { 4583270476aSTejun Heo return pool - pool->gcwq->pools; 4593270476aSTejun Heo } 4603270476aSTejun Heo 4618b03ae3cSTejun Heo static struct global_cwq *get_gcwq(unsigned int cpu) 4621da177e4SLinus Torvalds { 463f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 4648b03ae3cSTejun Heo return &per_cpu(global_cwq, cpu); 465f3421797STejun Heo else 466f3421797STejun Heo return &unbound_global_cwq; 4671da177e4SLinus Torvalds } 4681da177e4SLinus Torvalds 4699daf9e67STejun Heo /* allocate ID and assign it to @pool */ 4709daf9e67STejun Heo static int worker_pool_assign_id(struct worker_pool *pool) 4719daf9e67STejun Heo { 4729daf9e67STejun Heo int ret; 4739daf9e67STejun Heo 4749daf9e67STejun Heo mutex_lock(&worker_pool_idr_mutex); 4759daf9e67STejun Heo idr_pre_get(&worker_pool_idr, GFP_KERNEL); 4769daf9e67STejun Heo ret = idr_get_new(&worker_pool_idr, pool, &pool->id); 4779daf9e67STejun Heo mutex_unlock(&worker_pool_idr_mutex); 4789daf9e67STejun Heo 4799daf9e67STejun Heo return ret; 4809daf9e67STejun Heo } 4819daf9e67STejun Heo 48263d95a91STejun Heo static atomic_t *get_pool_nr_running(struct worker_pool *pool) 483b1f4ec17SOleg Nesterov { 48463d95a91STejun Heo int cpu = pool->gcwq->cpu; 485e34cdddbSTejun Heo int idx = std_worker_pool_pri(pool); 48663d95a91STejun Heo 487f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 4884ce62e9eSTejun Heo return &per_cpu(pool_nr_running, cpu)[idx]; 489f3421797STejun Heo else 4904ce62e9eSTejun Heo return &unbound_pool_nr_running[idx]; 491b1f4ec17SOleg Nesterov } 492b1f4ec17SOleg Nesterov 4934690c4abSTejun Heo static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, 4944690c4abSTejun Heo struct workqueue_struct *wq) 495a848e3b6SOleg Nesterov { 496f3421797STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 497e06ffa1eSLai Jiangshan if (likely(cpu < nr_cpu_ids)) 498bdbc5dd7STejun Heo return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); 499f3421797STejun Heo } else if (likely(cpu == WORK_CPU_UNBOUND)) 500f3421797STejun Heo return wq->cpu_wq.single; 501f3421797STejun Heo return NULL; 502f3421797STejun Heo } 503a848e3b6SOleg Nesterov 50473f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 50573f53c4aSTejun Heo { 50673f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 50773f53c4aSTejun Heo } 50873f53c4aSTejun Heo 50973f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 51073f53c4aSTejun Heo { 51173f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 51273f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 51373f53c4aSTejun Heo } 51473f53c4aSTejun Heo 51573f53c4aSTejun Heo static int work_next_color(int color) 51673f53c4aSTejun Heo { 51773f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 5181da177e4SLinus Torvalds } 5191da177e4SLinus Torvalds 5204594bf15SDavid Howells /* 521b5490077STejun Heo * While queued, %WORK_STRUCT_CWQ is set and non flag bits of a work's data 522b5490077STejun Heo * contain the pointer to the queued cwq. Once execution starts, the flag 523b5490077STejun Heo * is cleared and the high bits contain OFFQ flags and CPU number. 5247a22ad75STejun Heo * 525bbb68dfaSTejun Heo * set_work_cwq(), set_work_cpu_and_clear_pending(), mark_work_canceling() 526bbb68dfaSTejun Heo * and clear_work_data() can be used to set the cwq, cpu or clear 527bbb68dfaSTejun Heo * work->data. These functions should only be called while the work is 528bbb68dfaSTejun Heo * owned - ie. while the PENDING bit is set. 5297a22ad75STejun Heo * 530bbb68dfaSTejun Heo * get_work_[g]cwq() can be used to obtain the gcwq or cwq corresponding to 531bbb68dfaSTejun Heo * a work. gcwq is available once the work has been queued anywhere after 532bbb68dfaSTejun Heo * initialization until it is sync canceled. cwq is available only while 533bbb68dfaSTejun Heo * the work item is queued. 534bbb68dfaSTejun Heo * 535bbb68dfaSTejun Heo * %WORK_OFFQ_CANCELING is used to mark a work item which is being 536bbb68dfaSTejun Heo * canceled. While being canceled, a work item may have its PENDING set 537bbb68dfaSTejun Heo * but stay off timer and worklist for arbitrarily long and nobody should 538bbb68dfaSTejun Heo * try to steal the PENDING bit. 5394594bf15SDavid Howells */ 5407a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 5417a22ad75STejun Heo unsigned long flags) 5427a22ad75STejun Heo { 5437a22ad75STejun Heo BUG_ON(!work_pending(work)); 5447a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 5457a22ad75STejun Heo } 5467a22ad75STejun Heo 5477a22ad75STejun Heo static void set_work_cwq(struct work_struct *work, 5484690c4abSTejun Heo struct cpu_workqueue_struct *cwq, 5494690c4abSTejun Heo unsigned long extra_flags) 550365970a1SDavid Howells { 5517a22ad75STejun Heo set_work_data(work, (unsigned long)cwq, 552e120153dSTejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); 553365970a1SDavid Howells } 554365970a1SDavid Howells 5558930cabaSTejun Heo static void set_work_cpu_and_clear_pending(struct work_struct *work, 5568930cabaSTejun Heo unsigned int cpu) 5574d707b9fSOleg Nesterov { 55823657bb1STejun Heo /* 55923657bb1STejun Heo * The following wmb is paired with the implied mb in 56023657bb1STejun Heo * test_and_set_bit(PENDING) and ensures all updates to @work made 56123657bb1STejun Heo * here are visible to and precede any updates by the next PENDING 56223657bb1STejun Heo * owner. 56323657bb1STejun Heo */ 56423657bb1STejun Heo smp_wmb(); 565b5490077STejun Heo set_work_data(work, (unsigned long)cpu << WORK_OFFQ_CPU_SHIFT, 0); 5664d707b9fSOleg Nesterov } 5674d707b9fSOleg Nesterov 5687a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 569365970a1SDavid Howells { 57023657bb1STejun Heo smp_wmb(); /* see set_work_cpu_and_clear_pending() */ 5717a22ad75STejun Heo set_work_data(work, WORK_STRUCT_NO_CPU, 0); 5727a22ad75STejun Heo } 5737a22ad75STejun Heo 5747a22ad75STejun Heo static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) 5757a22ad75STejun Heo { 576e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5777a22ad75STejun Heo 578e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 579e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 580e120153dSTejun Heo else 581e120153dSTejun Heo return NULL; 5827a22ad75STejun Heo } 5837a22ad75STejun Heo 5847a22ad75STejun Heo static struct global_cwq *get_work_gcwq(struct work_struct *work) 5857a22ad75STejun Heo { 586e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5877a22ad75STejun Heo unsigned int cpu; 5887a22ad75STejun Heo 589e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 590e120153dSTejun Heo return ((struct cpu_workqueue_struct *) 591bd7bdd43STejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq; 5927a22ad75STejun Heo 593b5490077STejun Heo cpu = data >> WORK_OFFQ_CPU_SHIFT; 594715b06b8STejun Heo if (cpu == WORK_OFFQ_CPU_NONE) 5957a22ad75STejun Heo return NULL; 5967a22ad75STejun Heo 597f3421797STejun Heo BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); 5987a22ad75STejun Heo return get_gcwq(cpu); 599365970a1SDavid Howells } 600365970a1SDavid Howells 601bbb68dfaSTejun Heo static void mark_work_canceling(struct work_struct *work) 602bbb68dfaSTejun Heo { 603bbb68dfaSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 604715b06b8STejun Heo unsigned long cpu = gcwq ? gcwq->cpu : WORK_OFFQ_CPU_NONE; 605bbb68dfaSTejun Heo 606bbb68dfaSTejun Heo set_work_data(work, (cpu << WORK_OFFQ_CPU_SHIFT) | WORK_OFFQ_CANCELING, 607bbb68dfaSTejun Heo WORK_STRUCT_PENDING); 608bbb68dfaSTejun Heo } 609bbb68dfaSTejun Heo 610bbb68dfaSTejun Heo static bool work_is_canceling(struct work_struct *work) 611bbb68dfaSTejun Heo { 612bbb68dfaSTejun Heo unsigned long data = atomic_long_read(&work->data); 613bbb68dfaSTejun Heo 614bbb68dfaSTejun Heo return !(data & WORK_STRUCT_CWQ) && (data & WORK_OFFQ_CANCELING); 615bbb68dfaSTejun Heo } 616bbb68dfaSTejun Heo 617e22bee78STejun Heo /* 6183270476aSTejun Heo * Policy functions. These define the policies on how the global worker 6193270476aSTejun Heo * pools are managed. Unless noted otherwise, these functions assume that 6203270476aSTejun Heo * they're being called with gcwq->lock held. 621e22bee78STejun Heo */ 622e22bee78STejun Heo 62363d95a91STejun Heo static bool __need_more_worker(struct worker_pool *pool) 624649027d7STejun Heo { 6253270476aSTejun Heo return !atomic_read(get_pool_nr_running(pool)); 626649027d7STejun Heo } 627649027d7STejun Heo 628e22bee78STejun Heo /* 629e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 630e22bee78STejun Heo * running workers. 631974271c4STejun Heo * 632974271c4STejun Heo * Note that, because unbound workers never contribute to nr_running, this 633974271c4STejun Heo * function will always return %true for unbound gcwq as long as the 634974271c4STejun Heo * worklist isn't empty. 635e22bee78STejun Heo */ 63663d95a91STejun Heo static bool need_more_worker(struct worker_pool *pool) 637e22bee78STejun Heo { 63863d95a91STejun Heo return !list_empty(&pool->worklist) && __need_more_worker(pool); 639e22bee78STejun Heo } 640e22bee78STejun Heo 641e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 64263d95a91STejun Heo static bool may_start_working(struct worker_pool *pool) 643e22bee78STejun Heo { 64463d95a91STejun Heo return pool->nr_idle; 645e22bee78STejun Heo } 646e22bee78STejun Heo 647e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 64863d95a91STejun Heo static bool keep_working(struct worker_pool *pool) 649e22bee78STejun Heo { 65063d95a91STejun Heo atomic_t *nr_running = get_pool_nr_running(pool); 651e22bee78STejun Heo 6523270476aSTejun Heo return !list_empty(&pool->worklist) && atomic_read(nr_running) <= 1; 653e22bee78STejun Heo } 654e22bee78STejun Heo 655e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 65663d95a91STejun Heo static bool need_to_create_worker(struct worker_pool *pool) 657e22bee78STejun Heo { 65863d95a91STejun Heo return need_more_worker(pool) && !may_start_working(pool); 659e22bee78STejun Heo } 660e22bee78STejun Heo 661e22bee78STejun Heo /* Do I need to be the manager? */ 66263d95a91STejun Heo static bool need_to_manage_workers(struct worker_pool *pool) 663e22bee78STejun Heo { 66463d95a91STejun Heo return need_to_create_worker(pool) || 66511ebea50STejun Heo (pool->flags & POOL_MANAGE_WORKERS); 666e22bee78STejun Heo } 667e22bee78STejun Heo 668e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 66963d95a91STejun Heo static bool too_many_workers(struct worker_pool *pool) 670e22bee78STejun Heo { 671552a37e9SLai Jiangshan bool managing = pool->flags & POOL_MANAGING_WORKERS; 67263d95a91STejun Heo int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 67363d95a91STejun Heo int nr_busy = pool->nr_workers - nr_idle; 674e22bee78STejun Heo 675ea1abd61SLai Jiangshan /* 676ea1abd61SLai Jiangshan * nr_idle and idle_list may disagree if idle rebinding is in 677ea1abd61SLai Jiangshan * progress. Never return %true if idle_list is empty. 678ea1abd61SLai Jiangshan */ 679ea1abd61SLai Jiangshan if (list_empty(&pool->idle_list)) 680ea1abd61SLai Jiangshan return false; 681ea1abd61SLai Jiangshan 682e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 683e22bee78STejun Heo } 684e22bee78STejun Heo 685e22bee78STejun Heo /* 686e22bee78STejun Heo * Wake up functions. 687e22bee78STejun Heo */ 688e22bee78STejun Heo 6897e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 69063d95a91STejun Heo static struct worker *first_worker(struct worker_pool *pool) 6917e11629dSTejun Heo { 69263d95a91STejun Heo if (unlikely(list_empty(&pool->idle_list))) 6937e11629dSTejun Heo return NULL; 6947e11629dSTejun Heo 69563d95a91STejun Heo return list_first_entry(&pool->idle_list, struct worker, entry); 6967e11629dSTejun Heo } 6977e11629dSTejun Heo 6987e11629dSTejun Heo /** 6997e11629dSTejun Heo * wake_up_worker - wake up an idle worker 70063d95a91STejun Heo * @pool: worker pool to wake worker from 7017e11629dSTejun Heo * 70263d95a91STejun Heo * Wake up the first idle worker of @pool. 7037e11629dSTejun Heo * 7047e11629dSTejun Heo * CONTEXT: 7057e11629dSTejun Heo * spin_lock_irq(gcwq->lock). 7067e11629dSTejun Heo */ 70763d95a91STejun Heo static void wake_up_worker(struct worker_pool *pool) 7087e11629dSTejun Heo { 70963d95a91STejun Heo struct worker *worker = first_worker(pool); 7107e11629dSTejun Heo 7117e11629dSTejun Heo if (likely(worker)) 7127e11629dSTejun Heo wake_up_process(worker->task); 7137e11629dSTejun Heo } 7147e11629dSTejun Heo 7154690c4abSTejun Heo /** 716e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 717e22bee78STejun Heo * @task: task waking up 718e22bee78STejun Heo * @cpu: CPU @task is waking up to 719e22bee78STejun Heo * 720e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 721e22bee78STejun Heo * being awoken. 722e22bee78STejun Heo * 723e22bee78STejun Heo * CONTEXT: 724e22bee78STejun Heo * spin_lock_irq(rq->lock) 725e22bee78STejun Heo */ 726e22bee78STejun Heo void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) 727e22bee78STejun Heo { 728e22bee78STejun Heo struct worker *worker = kthread_data(task); 729e22bee78STejun Heo 73036576000SJoonsoo Kim if (!(worker->flags & WORKER_NOT_RUNNING)) { 73136576000SJoonsoo Kim WARN_ON_ONCE(worker->pool->gcwq->cpu != cpu); 73263d95a91STejun Heo atomic_inc(get_pool_nr_running(worker->pool)); 733e22bee78STejun Heo } 73436576000SJoonsoo Kim } 735e22bee78STejun Heo 736e22bee78STejun Heo /** 737e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 738e22bee78STejun Heo * @task: task going to sleep 739e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 740e22bee78STejun Heo * 741e22bee78STejun Heo * This function is called during schedule() when a busy worker is 742e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 743e22bee78STejun Heo * returning pointer to its task. 744e22bee78STejun Heo * 745e22bee78STejun Heo * CONTEXT: 746e22bee78STejun Heo * spin_lock_irq(rq->lock) 747e22bee78STejun Heo * 748e22bee78STejun Heo * RETURNS: 749e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 750e22bee78STejun Heo */ 751e22bee78STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, 752e22bee78STejun Heo unsigned int cpu) 753e22bee78STejun Heo { 754e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 755111c225aSTejun Heo struct worker_pool *pool; 756111c225aSTejun Heo atomic_t *nr_running; 757e22bee78STejun Heo 758111c225aSTejun Heo /* 759111c225aSTejun Heo * Rescuers, which may not have all the fields set up like normal 760111c225aSTejun Heo * workers, also reach here, let's not access anything before 761111c225aSTejun Heo * checking NOT_RUNNING. 762111c225aSTejun Heo */ 7632d64672eSSteven Rostedt if (worker->flags & WORKER_NOT_RUNNING) 764e22bee78STejun Heo return NULL; 765e22bee78STejun Heo 766111c225aSTejun Heo pool = worker->pool; 767111c225aSTejun Heo nr_running = get_pool_nr_running(pool); 768111c225aSTejun Heo 769e22bee78STejun Heo /* this can only happen on the local cpu */ 770e22bee78STejun Heo BUG_ON(cpu != raw_smp_processor_id()); 771e22bee78STejun Heo 772e22bee78STejun Heo /* 773e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 774e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 775e22bee78STejun Heo * Please read comment there. 776e22bee78STejun Heo * 777628c78e7STejun Heo * NOT_RUNNING is clear. This means that we're bound to and 778628c78e7STejun Heo * running on the local cpu w/ rq lock held and preemption 779628c78e7STejun Heo * disabled, which in turn means that none else could be 780628c78e7STejun Heo * manipulating idle_list, so dereferencing idle_list without gcwq 781628c78e7STejun Heo * lock is safe. 782e22bee78STejun Heo */ 783bd7bdd43STejun Heo if (atomic_dec_and_test(nr_running) && !list_empty(&pool->worklist)) 78463d95a91STejun Heo to_wakeup = first_worker(pool); 785e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 786e22bee78STejun Heo } 787e22bee78STejun Heo 788e22bee78STejun Heo /** 789e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 790cb444766STejun Heo * @worker: self 791d302f017STejun Heo * @flags: flags to set 792d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 793d302f017STejun Heo * 794e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 795e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 796e22bee78STejun Heo * woken up. 797d302f017STejun Heo * 798cb444766STejun Heo * CONTEXT: 799cb444766STejun Heo * spin_lock_irq(gcwq->lock) 800d302f017STejun Heo */ 801d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 802d302f017STejun Heo bool wakeup) 803d302f017STejun Heo { 804bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 805e22bee78STejun Heo 806cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 807cb444766STejun Heo 808e22bee78STejun Heo /* 809e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 810e22bee78STejun Heo * wake up an idle worker as necessary if requested by 811e22bee78STejun Heo * @wakeup. 812e22bee78STejun Heo */ 813e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 814e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 81563d95a91STejun Heo atomic_t *nr_running = get_pool_nr_running(pool); 816e22bee78STejun Heo 817e22bee78STejun Heo if (wakeup) { 818e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && 819bd7bdd43STejun Heo !list_empty(&pool->worklist)) 82063d95a91STejun Heo wake_up_worker(pool); 821e22bee78STejun Heo } else 822e22bee78STejun Heo atomic_dec(nr_running); 823e22bee78STejun Heo } 824e22bee78STejun Heo 825d302f017STejun Heo worker->flags |= flags; 826d302f017STejun Heo } 827d302f017STejun Heo 828d302f017STejun Heo /** 829e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 830cb444766STejun Heo * @worker: self 831d302f017STejun Heo * @flags: flags to clear 832d302f017STejun Heo * 833e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 834d302f017STejun Heo * 835cb444766STejun Heo * CONTEXT: 836cb444766STejun Heo * spin_lock_irq(gcwq->lock) 837d302f017STejun Heo */ 838d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 839d302f017STejun Heo { 84063d95a91STejun Heo struct worker_pool *pool = worker->pool; 841e22bee78STejun Heo unsigned int oflags = worker->flags; 842e22bee78STejun Heo 843cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 844cb444766STejun Heo 845d302f017STejun Heo worker->flags &= ~flags; 846e22bee78STejun Heo 84742c025f3STejun Heo /* 84842c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 84942c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 85042c025f3STejun Heo * of multiple flags, not a single flag. 85142c025f3STejun Heo */ 852e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 853e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 85463d95a91STejun Heo atomic_inc(get_pool_nr_running(pool)); 855d302f017STejun Heo } 856d302f017STejun Heo 857d302f017STejun Heo /** 8588cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 8598cca0eeaSTejun Heo * @gcwq: gcwq of interest 8608cca0eeaSTejun Heo * @work: work to find worker for 8618cca0eeaSTejun Heo * 862a2c1c57bSTejun Heo * Find a worker which is executing @work on @gcwq by searching 863a2c1c57bSTejun Heo * @gcwq->busy_hash which is keyed by the address of @work. For a worker 864a2c1c57bSTejun Heo * to match, its current execution should match the address of @work and 865a2c1c57bSTejun Heo * its work function. This is to avoid unwanted dependency between 866a2c1c57bSTejun Heo * unrelated work executions through a work item being recycled while still 867a2c1c57bSTejun Heo * being executed. 868a2c1c57bSTejun Heo * 869a2c1c57bSTejun Heo * This is a bit tricky. A work item may be freed once its execution 870a2c1c57bSTejun Heo * starts and nothing prevents the freed area from being recycled for 871a2c1c57bSTejun Heo * another work item. If the same work item address ends up being reused 872a2c1c57bSTejun Heo * before the original execution finishes, workqueue will identify the 873a2c1c57bSTejun Heo * recycled work item as currently executing and make it wait until the 874a2c1c57bSTejun Heo * current execution finishes, introducing an unwanted dependency. 875a2c1c57bSTejun Heo * 876a2c1c57bSTejun Heo * This function checks the work item address, work function and workqueue 877a2c1c57bSTejun Heo * to avoid false positives. Note that this isn't complete as one may 878a2c1c57bSTejun Heo * construct a work function which can introduce dependency onto itself 879a2c1c57bSTejun Heo * through a recycled work item. Well, if somebody wants to shoot oneself 880a2c1c57bSTejun Heo * in the foot that badly, there's only so much we can do, and if such 881a2c1c57bSTejun Heo * deadlock actually occurs, it should be easy to locate the culprit work 882a2c1c57bSTejun Heo * function. 8838cca0eeaSTejun Heo * 8848cca0eeaSTejun Heo * CONTEXT: 8858cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8868cca0eeaSTejun Heo * 8878cca0eeaSTejun Heo * RETURNS: 8888cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8898cca0eeaSTejun Heo * otherwise. 8908cca0eeaSTejun Heo */ 8918cca0eeaSTejun Heo static struct worker *find_worker_executing_work(struct global_cwq *gcwq, 8928cca0eeaSTejun Heo struct work_struct *work) 8938cca0eeaSTejun Heo { 89442f8570fSSasha Levin struct worker *worker; 89542f8570fSSasha Levin struct hlist_node *tmp; 89642f8570fSSasha Levin 897a2c1c57bSTejun Heo hash_for_each_possible(gcwq->busy_hash, worker, tmp, hentry, 898a2c1c57bSTejun Heo (unsigned long)work) 899a2c1c57bSTejun Heo if (worker->current_work == work && 900a2c1c57bSTejun Heo worker->current_func == work->func) 90142f8570fSSasha Levin return worker; 90242f8570fSSasha Levin 90342f8570fSSasha Levin return NULL; 9048cca0eeaSTejun Heo } 9058cca0eeaSTejun Heo 9068cca0eeaSTejun Heo /** 907bf4ede01STejun Heo * move_linked_works - move linked works to a list 908bf4ede01STejun Heo * @work: start of series of works to be scheduled 909bf4ede01STejun Heo * @head: target list to append @work to 910bf4ede01STejun Heo * @nextp: out paramter for nested worklist walking 911bf4ede01STejun Heo * 912bf4ede01STejun Heo * Schedule linked works starting from @work to @head. Work series to 913bf4ede01STejun Heo * be scheduled starts at @work and includes any consecutive work with 914bf4ede01STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 915bf4ede01STejun Heo * 916bf4ede01STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 917bf4ede01STejun Heo * the last scheduled work. This allows move_linked_works() to be 918bf4ede01STejun Heo * nested inside outer list_for_each_entry_safe(). 919bf4ede01STejun Heo * 920bf4ede01STejun Heo * CONTEXT: 921bf4ede01STejun Heo * spin_lock_irq(gcwq->lock). 922bf4ede01STejun Heo */ 923bf4ede01STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 924bf4ede01STejun Heo struct work_struct **nextp) 925bf4ede01STejun Heo { 926bf4ede01STejun Heo struct work_struct *n; 927bf4ede01STejun Heo 928bf4ede01STejun Heo /* 929bf4ede01STejun Heo * Linked worklist will always end before the end of the list, 930bf4ede01STejun Heo * use NULL for list head. 931bf4ede01STejun Heo */ 932bf4ede01STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 933bf4ede01STejun Heo list_move_tail(&work->entry, head); 934bf4ede01STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 935bf4ede01STejun Heo break; 936bf4ede01STejun Heo } 937bf4ede01STejun Heo 938bf4ede01STejun Heo /* 939bf4ede01STejun Heo * If we're already inside safe list traversal and have moved 940bf4ede01STejun Heo * multiple works to the scheduled queue, the next position 941bf4ede01STejun Heo * needs to be updated. 942bf4ede01STejun Heo */ 943bf4ede01STejun Heo if (nextp) 944bf4ede01STejun Heo *nextp = n; 945bf4ede01STejun Heo } 946bf4ede01STejun Heo 9473aa62497SLai Jiangshan static void cwq_activate_delayed_work(struct work_struct *work) 948bf4ede01STejun Heo { 9493aa62497SLai Jiangshan struct cpu_workqueue_struct *cwq = get_work_cwq(work); 950bf4ede01STejun Heo 951bf4ede01STejun Heo trace_workqueue_activate_work(work); 952bf4ede01STejun Heo move_linked_works(work, &cwq->pool->worklist, NULL); 953bf4ede01STejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 954bf4ede01STejun Heo cwq->nr_active++; 955bf4ede01STejun Heo } 956bf4ede01STejun Heo 9573aa62497SLai Jiangshan static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) 9583aa62497SLai Jiangshan { 9593aa62497SLai Jiangshan struct work_struct *work = list_first_entry(&cwq->delayed_works, 9603aa62497SLai Jiangshan struct work_struct, entry); 9613aa62497SLai Jiangshan 9623aa62497SLai Jiangshan cwq_activate_delayed_work(work); 9633aa62497SLai Jiangshan } 9643aa62497SLai Jiangshan 965bf4ede01STejun Heo /** 966bf4ede01STejun Heo * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight 967bf4ede01STejun Heo * @cwq: cwq of interest 968bf4ede01STejun Heo * @color: color of work which left the queue 969bf4ede01STejun Heo * 970bf4ede01STejun Heo * A work either has completed or is removed from pending queue, 971bf4ede01STejun Heo * decrement nr_in_flight of its cwq and handle workqueue flushing. 972bf4ede01STejun Heo * 973bf4ede01STejun Heo * CONTEXT: 974bf4ede01STejun Heo * spin_lock_irq(gcwq->lock). 975bf4ede01STejun Heo */ 976b3f9f405SLai Jiangshan static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) 977bf4ede01STejun Heo { 978bf4ede01STejun Heo /* ignore uncolored works */ 979bf4ede01STejun Heo if (color == WORK_NO_COLOR) 980bf4ede01STejun Heo return; 981bf4ede01STejun Heo 982bf4ede01STejun Heo cwq->nr_in_flight[color]--; 983bf4ede01STejun Heo 984bf4ede01STejun Heo cwq->nr_active--; 985bf4ede01STejun Heo if (!list_empty(&cwq->delayed_works)) { 986bf4ede01STejun Heo /* one down, submit a delayed one */ 987bf4ede01STejun Heo if (cwq->nr_active < cwq->max_active) 988bf4ede01STejun Heo cwq_activate_first_delayed(cwq); 989bf4ede01STejun Heo } 990bf4ede01STejun Heo 991bf4ede01STejun Heo /* is flush in progress and are we at the flushing tip? */ 992bf4ede01STejun Heo if (likely(cwq->flush_color != color)) 993bf4ede01STejun Heo return; 994bf4ede01STejun Heo 995bf4ede01STejun Heo /* are there still in-flight works? */ 996bf4ede01STejun Heo if (cwq->nr_in_flight[color]) 997bf4ede01STejun Heo return; 998bf4ede01STejun Heo 999bf4ede01STejun Heo /* this cwq is done, clear flush_color */ 1000bf4ede01STejun Heo cwq->flush_color = -1; 1001bf4ede01STejun Heo 1002bf4ede01STejun Heo /* 1003bf4ede01STejun Heo * If this was the last cwq, wake up the first flusher. It 1004bf4ede01STejun Heo * will handle the rest. 1005bf4ede01STejun Heo */ 1006bf4ede01STejun Heo if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) 1007bf4ede01STejun Heo complete(&cwq->wq->first_flusher->done); 1008bf4ede01STejun Heo } 1009bf4ede01STejun Heo 101036e227d2STejun Heo /** 1011bbb68dfaSTejun Heo * try_to_grab_pending - steal work item from worklist and disable irq 101236e227d2STejun Heo * @work: work item to steal 101336e227d2STejun Heo * @is_dwork: @work is a delayed_work 1014bbb68dfaSTejun Heo * @flags: place to store irq state 101536e227d2STejun Heo * 101636e227d2STejun Heo * Try to grab PENDING bit of @work. This function can handle @work in any 101736e227d2STejun Heo * stable state - idle, on timer or on worklist. Return values are 101836e227d2STejun Heo * 101936e227d2STejun Heo * 1 if @work was pending and we successfully stole PENDING 102036e227d2STejun Heo * 0 if @work was idle and we claimed PENDING 102136e227d2STejun Heo * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 1022bbb68dfaSTejun Heo * -ENOENT if someone else is canceling @work, this state may persist 1023bbb68dfaSTejun Heo * for arbitrarily long 102436e227d2STejun Heo * 1025bbb68dfaSTejun Heo * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 1026e0aecdd8STejun Heo * interrupted while holding PENDING and @work off queue, irq must be 1027e0aecdd8STejun Heo * disabled on entry. This, combined with delayed_work->timer being 1028e0aecdd8STejun Heo * irqsafe, ensures that we return -EAGAIN for finite short period of time. 1029bbb68dfaSTejun Heo * 1030bbb68dfaSTejun Heo * On successful return, >= 0, irq is disabled and the caller is 1031bbb68dfaSTejun Heo * responsible for releasing it using local_irq_restore(*@flags). 1032bbb68dfaSTejun Heo * 1033e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 1034bf4ede01STejun Heo */ 1035bbb68dfaSTejun Heo static int try_to_grab_pending(struct work_struct *work, bool is_dwork, 1036bbb68dfaSTejun Heo unsigned long *flags) 1037bf4ede01STejun Heo { 1038bf4ede01STejun Heo struct global_cwq *gcwq; 1039bf4ede01STejun Heo 1040bbb68dfaSTejun Heo local_irq_save(*flags); 1041bbb68dfaSTejun Heo 104236e227d2STejun Heo /* try to steal the timer if it exists */ 104336e227d2STejun Heo if (is_dwork) { 104436e227d2STejun Heo struct delayed_work *dwork = to_delayed_work(work); 104536e227d2STejun Heo 1046e0aecdd8STejun Heo /* 1047e0aecdd8STejun Heo * dwork->timer is irqsafe. If del_timer() fails, it's 1048e0aecdd8STejun Heo * guaranteed that the timer is not queued anywhere and not 1049e0aecdd8STejun Heo * running on the local CPU. 1050e0aecdd8STejun Heo */ 105136e227d2STejun Heo if (likely(del_timer(&dwork->timer))) 105236e227d2STejun Heo return 1; 105336e227d2STejun Heo } 105436e227d2STejun Heo 105536e227d2STejun Heo /* try to claim PENDING the normal way */ 1056bf4ede01STejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 1057bf4ede01STejun Heo return 0; 1058bf4ede01STejun Heo 1059bf4ede01STejun Heo /* 1060bf4ede01STejun Heo * The queueing is in progress, or it is already queued. Try to 1061bf4ede01STejun Heo * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 1062bf4ede01STejun Heo */ 1063bf4ede01STejun Heo gcwq = get_work_gcwq(work); 1064bf4ede01STejun Heo if (!gcwq) 1065bbb68dfaSTejun Heo goto fail; 1066bf4ede01STejun Heo 1067bbb68dfaSTejun Heo spin_lock(&gcwq->lock); 1068bf4ede01STejun Heo if (!list_empty(&work->entry)) { 1069bf4ede01STejun Heo /* 1070bf4ede01STejun Heo * This work is queued, but perhaps we locked the wrong gcwq. 1071bf4ede01STejun Heo * In that case we must see the new value after rmb(), see 1072bf4ede01STejun Heo * insert_work()->wmb(). 1073bf4ede01STejun Heo */ 1074bf4ede01STejun Heo smp_rmb(); 1075bf4ede01STejun Heo if (gcwq == get_work_gcwq(work)) { 1076bf4ede01STejun Heo debug_work_deactivate(work); 10773aa62497SLai Jiangshan 10783aa62497SLai Jiangshan /* 10793aa62497SLai Jiangshan * A delayed work item cannot be grabbed directly 10803aa62497SLai Jiangshan * because it might have linked NO_COLOR work items 10813aa62497SLai Jiangshan * which, if left on the delayed_list, will confuse 10823aa62497SLai Jiangshan * cwq->nr_active management later on and cause 10833aa62497SLai Jiangshan * stall. Make sure the work item is activated 10843aa62497SLai Jiangshan * before grabbing. 10853aa62497SLai Jiangshan */ 10863aa62497SLai Jiangshan if (*work_data_bits(work) & WORK_STRUCT_DELAYED) 10873aa62497SLai Jiangshan cwq_activate_delayed_work(work); 10883aa62497SLai Jiangshan 1089bf4ede01STejun Heo list_del_init(&work->entry); 1090bf4ede01STejun Heo cwq_dec_nr_in_flight(get_work_cwq(work), 1091b3f9f405SLai Jiangshan get_work_color(work)); 109236e227d2STejun Heo 1093bbb68dfaSTejun Heo spin_unlock(&gcwq->lock); 109436e227d2STejun Heo return 1; 1095bf4ede01STejun Heo } 1096bf4ede01STejun Heo } 1097bbb68dfaSTejun Heo spin_unlock(&gcwq->lock); 1098bbb68dfaSTejun Heo fail: 1099bbb68dfaSTejun Heo local_irq_restore(*flags); 1100bbb68dfaSTejun Heo if (work_is_canceling(work)) 1101bbb68dfaSTejun Heo return -ENOENT; 1102bbb68dfaSTejun Heo cpu_relax(); 110336e227d2STejun Heo return -EAGAIN; 1104bf4ede01STejun Heo } 1105bf4ede01STejun Heo 1106bf4ede01STejun Heo /** 11077e11629dSTejun Heo * insert_work - insert a work into gcwq 11084690c4abSTejun Heo * @cwq: cwq @work belongs to 11094690c4abSTejun Heo * @work: work to insert 11104690c4abSTejun Heo * @head: insertion point 11114690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 11124690c4abSTejun Heo * 11137e11629dSTejun Heo * Insert @work which belongs to @cwq into @gcwq after @head. 11147e11629dSTejun Heo * @extra_flags is or'd to work_struct flags. 11154690c4abSTejun Heo * 11164690c4abSTejun Heo * CONTEXT: 11178b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 11181da177e4SLinus Torvalds */ 1119b89deed3SOleg Nesterov static void insert_work(struct cpu_workqueue_struct *cwq, 11204690c4abSTejun Heo struct work_struct *work, struct list_head *head, 11214690c4abSTejun Heo unsigned int extra_flags) 1122b89deed3SOleg Nesterov { 112363d95a91STejun Heo struct worker_pool *pool = cwq->pool; 1124e1d8aa9fSFrederic Weisbecker 11254690c4abSTejun Heo /* we own @work, set data and link */ 11267a22ad75STejun Heo set_work_cwq(work, cwq, extra_flags); 11274690c4abSTejun Heo 11286e84d644SOleg Nesterov /* 11296e84d644SOleg Nesterov * Ensure that we get the right work->data if we see the 11306e84d644SOleg Nesterov * result of list_add() below, see try_to_grab_pending(). 11316e84d644SOleg Nesterov */ 11326e84d644SOleg Nesterov smp_wmb(); 11334690c4abSTejun Heo 11341a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 1135e22bee78STejun Heo 1136e22bee78STejun Heo /* 1137e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 1138e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 1139e22bee78STejun Heo * lying around lazily while there are works to be processed. 1140e22bee78STejun Heo */ 1141e22bee78STejun Heo smp_mb(); 1142e22bee78STejun Heo 114363d95a91STejun Heo if (__need_more_worker(pool)) 114463d95a91STejun Heo wake_up_worker(pool); 1145b89deed3SOleg Nesterov } 1146b89deed3SOleg Nesterov 1147c8efcc25STejun Heo /* 1148c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 1149c8efcc25STejun Heo * same workqueue. This is rather expensive and should only be used from 1150c8efcc25STejun Heo * cold paths. 1151c8efcc25STejun Heo */ 1152c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 1153c8efcc25STejun Heo { 1154c8efcc25STejun Heo unsigned long flags; 1155c8efcc25STejun Heo unsigned int cpu; 1156c8efcc25STejun Heo 1157c8efcc25STejun Heo for_each_gcwq_cpu(cpu) { 1158c8efcc25STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 1159c8efcc25STejun Heo struct worker *worker; 1160c8efcc25STejun Heo struct hlist_node *pos; 1161c8efcc25STejun Heo int i; 1162c8efcc25STejun Heo 1163c8efcc25STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 1164c8efcc25STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 1165c8efcc25STejun Heo if (worker->task != current) 1166c8efcc25STejun Heo continue; 1167c8efcc25STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 1168c8efcc25STejun Heo /* 1169c8efcc25STejun Heo * I'm @worker, no locking necessary. See if @work 1170c8efcc25STejun Heo * is headed to the same workqueue. 1171c8efcc25STejun Heo */ 1172c8efcc25STejun Heo return worker->current_cwq->wq == wq; 1173c8efcc25STejun Heo } 1174c8efcc25STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 1175c8efcc25STejun Heo } 1176c8efcc25STejun Heo return false; 1177c8efcc25STejun Heo } 1178c8efcc25STejun Heo 11794690c4abSTejun Heo static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 11801da177e4SLinus Torvalds struct work_struct *work) 11811da177e4SLinus Torvalds { 1182502ca9d8STejun Heo struct global_cwq *gcwq; 1183502ca9d8STejun Heo struct cpu_workqueue_struct *cwq; 11841e19ffc6STejun Heo struct list_head *worklist; 11858a2e8e5dSTejun Heo unsigned int work_flags; 1186b75cac93SJoonsoo Kim unsigned int req_cpu = cpu; 11878930cabaSTejun Heo 11888930cabaSTejun Heo /* 11898930cabaSTejun Heo * While a work item is PENDING && off queue, a task trying to 11908930cabaSTejun Heo * steal the PENDING will busy-loop waiting for it to either get 11918930cabaSTejun Heo * queued or lose PENDING. Grabbing PENDING and queueing should 11928930cabaSTejun Heo * happen with IRQ disabled. 11938930cabaSTejun Heo */ 11948930cabaSTejun Heo WARN_ON_ONCE(!irqs_disabled()); 11951da177e4SLinus Torvalds 1196dc186ad7SThomas Gleixner debug_work_activate(work); 11971e19ffc6STejun Heo 1198c8efcc25STejun Heo /* if dying, only works from the same workqueue are allowed */ 11999c5a2ba7STejun Heo if (unlikely(wq->flags & WQ_DRAINING) && 1200c8efcc25STejun Heo WARN_ON_ONCE(!is_chained_work(wq))) 1201e41e704bSTejun Heo return; 1202e41e704bSTejun Heo 1203c7fc77f7STejun Heo /* determine gcwq to use */ 1204c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1205c7fc77f7STejun Heo struct global_cwq *last_gcwq; 1206c7fc77f7STejun Heo 120757469821STejun Heo if (cpu == WORK_CPU_UNBOUND) 1208f3421797STejun Heo cpu = raw_smp_processor_id(); 1209f3421797STejun Heo 121018aa9effSTejun Heo /* 1211dbf2576eSTejun Heo * It's multi cpu. If @work was previously on a different 1212dbf2576eSTejun Heo * cpu, it might still be running there, in which case the 1213dbf2576eSTejun Heo * work needs to be queued on that cpu to guarantee 1214dbf2576eSTejun Heo * non-reentrancy. 121518aa9effSTejun Heo */ 1216502ca9d8STejun Heo gcwq = get_gcwq(cpu); 1217dbf2576eSTejun Heo last_gcwq = get_work_gcwq(work); 1218dbf2576eSTejun Heo 1219dbf2576eSTejun Heo if (last_gcwq && last_gcwq != gcwq) { 122018aa9effSTejun Heo struct worker *worker; 122118aa9effSTejun Heo 12228930cabaSTejun Heo spin_lock(&last_gcwq->lock); 122318aa9effSTejun Heo 122418aa9effSTejun Heo worker = find_worker_executing_work(last_gcwq, work); 122518aa9effSTejun Heo 122618aa9effSTejun Heo if (worker && worker->current_cwq->wq == wq) 122718aa9effSTejun Heo gcwq = last_gcwq; 122818aa9effSTejun Heo else { 122918aa9effSTejun Heo /* meh... not running there, queue here */ 12308930cabaSTejun Heo spin_unlock(&last_gcwq->lock); 12318930cabaSTejun Heo spin_lock(&gcwq->lock); 123218aa9effSTejun Heo } 12338930cabaSTejun Heo } else { 12348930cabaSTejun Heo spin_lock(&gcwq->lock); 12358930cabaSTejun Heo } 1236f3421797STejun Heo } else { 1237f3421797STejun Heo gcwq = get_gcwq(WORK_CPU_UNBOUND); 12388930cabaSTejun Heo spin_lock(&gcwq->lock); 1239502ca9d8STejun Heo } 1240502ca9d8STejun Heo 1241502ca9d8STejun Heo /* gcwq determined, get cwq and queue */ 1242502ca9d8STejun Heo cwq = get_cwq(gcwq->cpu, wq); 1243b75cac93SJoonsoo Kim trace_workqueue_queue_work(req_cpu, cwq, work); 1244502ca9d8STejun Heo 1245f5b2552bSDan Carpenter if (WARN_ON(!list_empty(&work->entry))) { 12468930cabaSTejun Heo spin_unlock(&gcwq->lock); 1247f5b2552bSDan Carpenter return; 1248f5b2552bSDan Carpenter } 12491e19ffc6STejun Heo 125073f53c4aSTejun Heo cwq->nr_in_flight[cwq->work_color]++; 12518a2e8e5dSTejun Heo work_flags = work_color_to_flags(cwq->work_color); 12521e19ffc6STejun Heo 12531e19ffc6STejun Heo if (likely(cwq->nr_active < cwq->max_active)) { 1254cdadf009STejun Heo trace_workqueue_activate_work(work); 12551e19ffc6STejun Heo cwq->nr_active++; 12563270476aSTejun Heo worklist = &cwq->pool->worklist; 12578a2e8e5dSTejun Heo } else { 12588a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 12591e19ffc6STejun Heo worklist = &cwq->delayed_works; 12608a2e8e5dSTejun Heo } 12611e19ffc6STejun Heo 12628a2e8e5dSTejun Heo insert_work(cwq, work, worklist, work_flags); 12631e19ffc6STejun Heo 12648930cabaSTejun Heo spin_unlock(&gcwq->lock); 12651da177e4SLinus Torvalds } 12661da177e4SLinus Torvalds 12670fcb78c2SRolf Eike Beer /** 1268c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1269c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1270c1a220e7SZhang Rui * @wq: workqueue to use 1271c1a220e7SZhang Rui * @work: work to queue 1272c1a220e7SZhang Rui * 1273d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 1274c1a220e7SZhang Rui * 1275c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1276c1a220e7SZhang Rui * can't go away. 1277c1a220e7SZhang Rui */ 1278d4283e93STejun Heo bool queue_work_on(int cpu, struct workqueue_struct *wq, 1279d4283e93STejun Heo struct work_struct *work) 1280c1a220e7SZhang Rui { 1281d4283e93STejun Heo bool ret = false; 12828930cabaSTejun Heo unsigned long flags; 12838930cabaSTejun Heo 12848930cabaSTejun Heo local_irq_save(flags); 1285c1a220e7SZhang Rui 128622df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 12874690c4abSTejun Heo __queue_work(cpu, wq, work); 1288d4283e93STejun Heo ret = true; 1289c1a220e7SZhang Rui } 12908930cabaSTejun Heo 12918930cabaSTejun Heo local_irq_restore(flags); 1292c1a220e7SZhang Rui return ret; 1293c1a220e7SZhang Rui } 1294c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1295c1a220e7SZhang Rui 12960a13c00eSTejun Heo /** 12970a13c00eSTejun Heo * queue_work - queue work on a workqueue 12980a13c00eSTejun Heo * @wq: workqueue to use 12990a13c00eSTejun Heo * @work: work to queue 13000a13c00eSTejun Heo * 1301d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 13020a13c00eSTejun Heo * 13030a13c00eSTejun Heo * We queue the work to the CPU on which it was submitted, but if the CPU dies 13040a13c00eSTejun Heo * it can be processed by another CPU. 13050a13c00eSTejun Heo */ 1306d4283e93STejun Heo bool queue_work(struct workqueue_struct *wq, struct work_struct *work) 13070a13c00eSTejun Heo { 130857469821STejun Heo return queue_work_on(WORK_CPU_UNBOUND, wq, work); 13090a13c00eSTejun Heo } 13100a13c00eSTejun Heo EXPORT_SYMBOL_GPL(queue_work); 13110a13c00eSTejun Heo 1312d8e794dfSTejun Heo void delayed_work_timer_fn(unsigned long __data) 13131da177e4SLinus Torvalds { 131452bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 13157a22ad75STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); 13161da177e4SLinus Torvalds 1317e0aecdd8STejun Heo /* should have been called from irqsafe timer with irq already off */ 13181265057fSTejun Heo __queue_work(dwork->cpu, cwq->wq, &dwork->work); 13191da177e4SLinus Torvalds } 1320d8e794dfSTejun Heo EXPORT_SYMBOL_GPL(delayed_work_timer_fn); 13211da177e4SLinus Torvalds 13227beb2edfSTejun Heo static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 132352bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 13241da177e4SLinus Torvalds { 13257beb2edfSTejun Heo struct timer_list *timer = &dwork->timer; 13267beb2edfSTejun Heo struct work_struct *work = &dwork->work; 13277beb2edfSTejun Heo unsigned int lcpu; 13281da177e4SLinus Torvalds 13297beb2edfSTejun Heo WARN_ON_ONCE(timer->function != delayed_work_timer_fn || 13307beb2edfSTejun Heo timer->data != (unsigned long)dwork); 1331fc4b514fSTejun Heo WARN_ON_ONCE(timer_pending(timer)); 1332fc4b514fSTejun Heo WARN_ON_ONCE(!list_empty(&work->entry)); 13337beb2edfSTejun Heo 13348852aac2STejun Heo /* 13358852aac2STejun Heo * If @delay is 0, queue @dwork->work immediately. This is for 13368852aac2STejun Heo * both optimization and correctness. The earliest @timer can 13378852aac2STejun Heo * expire is on the closest next tick and delayed_work users depend 13388852aac2STejun Heo * on that there's no such delay when @delay is 0. 13398852aac2STejun Heo */ 13408852aac2STejun Heo if (!delay) { 13418852aac2STejun Heo __queue_work(cpu, wq, &dwork->work); 13428852aac2STejun Heo return; 13438852aac2STejun Heo } 13448852aac2STejun Heo 13457beb2edfSTejun Heo timer_stats_timer_set_start_info(&dwork->timer); 13467beb2edfSTejun Heo 13477beb2edfSTejun Heo /* 13487beb2edfSTejun Heo * This stores cwq for the moment, for the timer_fn. Note that the 13497beb2edfSTejun Heo * work's gcwq is preserved to allow reentrance detection for 13507beb2edfSTejun Heo * delayed works. 13517beb2edfSTejun Heo */ 13527beb2edfSTejun Heo if (!(wq->flags & WQ_UNBOUND)) { 13537beb2edfSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 13547beb2edfSTejun Heo 1355e42986deSJoonsoo Kim /* 1356e42986deSJoonsoo Kim * If we cannot get the last gcwq from @work directly, 1357e42986deSJoonsoo Kim * select the last CPU such that it avoids unnecessarily 1358e42986deSJoonsoo Kim * triggering non-reentrancy check in __queue_work(). 1359e42986deSJoonsoo Kim */ 1360e42986deSJoonsoo Kim lcpu = cpu; 1361e42986deSJoonsoo Kim if (gcwq) 13627beb2edfSTejun Heo lcpu = gcwq->cpu; 1363e42986deSJoonsoo Kim if (lcpu == WORK_CPU_UNBOUND) 13647beb2edfSTejun Heo lcpu = raw_smp_processor_id(); 13657beb2edfSTejun Heo } else { 13667beb2edfSTejun Heo lcpu = WORK_CPU_UNBOUND; 13671da177e4SLinus Torvalds } 13687beb2edfSTejun Heo 13697beb2edfSTejun Heo set_work_cwq(work, get_cwq(lcpu, wq), 0); 13707beb2edfSTejun Heo 13711265057fSTejun Heo dwork->cpu = cpu; 13727beb2edfSTejun Heo timer->expires = jiffies + delay; 13737beb2edfSTejun Heo 13747beb2edfSTejun Heo if (unlikely(cpu != WORK_CPU_UNBOUND)) 13757beb2edfSTejun Heo add_timer_on(timer, cpu); 13767beb2edfSTejun Heo else 13777beb2edfSTejun Heo add_timer(timer); 13787beb2edfSTejun Heo } 13791da177e4SLinus Torvalds 13800fcb78c2SRolf Eike Beer /** 13810fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 13820fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 13830fcb78c2SRolf Eike Beer * @wq: workqueue to use 1384af9997e4SRandy Dunlap * @dwork: work to queue 13850fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 13860fcb78c2SRolf Eike Beer * 1387715f1300STejun Heo * Returns %false if @work was already on a queue, %true otherwise. If 1388715f1300STejun Heo * @delay is zero and @dwork is idle, it will be scheduled for immediate 1389715f1300STejun Heo * execution. 13900fcb78c2SRolf Eike Beer */ 1391d4283e93STejun Heo bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 139252bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 13937a6bc1cdSVenkatesh Pallipadi { 139452bad64dSDavid Howells struct work_struct *work = &dwork->work; 1395d4283e93STejun Heo bool ret = false; 13968930cabaSTejun Heo unsigned long flags; 13978930cabaSTejun Heo 13988930cabaSTejun Heo /* read the comment in __queue_work() */ 13998930cabaSTejun Heo local_irq_save(flags); 14007a6bc1cdSVenkatesh Pallipadi 140122df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 14027beb2edfSTejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 1403d4283e93STejun Heo ret = true; 14047a6bc1cdSVenkatesh Pallipadi } 14058930cabaSTejun Heo 14068930cabaSTejun Heo local_irq_restore(flags); 14077a6bc1cdSVenkatesh Pallipadi return ret; 14087a6bc1cdSVenkatesh Pallipadi } 1409ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 14101da177e4SLinus Torvalds 1411c8e55f36STejun Heo /** 14120a13c00eSTejun Heo * queue_delayed_work - queue work on a workqueue after delay 14130a13c00eSTejun Heo * @wq: workqueue to use 14140a13c00eSTejun Heo * @dwork: delayable work to queue 14150a13c00eSTejun Heo * @delay: number of jiffies to wait before queueing 14160a13c00eSTejun Heo * 1417715f1300STejun Heo * Equivalent to queue_delayed_work_on() but tries to use the local CPU. 14180a13c00eSTejun Heo */ 1419d4283e93STejun Heo bool queue_delayed_work(struct workqueue_struct *wq, 14200a13c00eSTejun Heo struct delayed_work *dwork, unsigned long delay) 14210a13c00eSTejun Heo { 142257469821STejun Heo return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); 14230a13c00eSTejun Heo } 14240a13c00eSTejun Heo EXPORT_SYMBOL_GPL(queue_delayed_work); 14250a13c00eSTejun Heo 14260a13c00eSTejun Heo /** 14278376fe22STejun Heo * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 14288376fe22STejun Heo * @cpu: CPU number to execute work on 14298376fe22STejun Heo * @wq: workqueue to use 14308376fe22STejun Heo * @dwork: work to queue 14318376fe22STejun Heo * @delay: number of jiffies to wait before queueing 14328376fe22STejun Heo * 14338376fe22STejun Heo * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 14348376fe22STejun Heo * modify @dwork's timer so that it expires after @delay. If @delay is 14358376fe22STejun Heo * zero, @work is guaranteed to be scheduled immediately regardless of its 14368376fe22STejun Heo * current state. 14378376fe22STejun Heo * 14388376fe22STejun Heo * Returns %false if @dwork was idle and queued, %true if @dwork was 14398376fe22STejun Heo * pending and its timer was modified. 14408376fe22STejun Heo * 1441e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 14428376fe22STejun Heo * See try_to_grab_pending() for details. 14438376fe22STejun Heo */ 14448376fe22STejun Heo bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 14458376fe22STejun Heo struct delayed_work *dwork, unsigned long delay) 14468376fe22STejun Heo { 14478376fe22STejun Heo unsigned long flags; 14488376fe22STejun Heo int ret; 14498376fe22STejun Heo 14508376fe22STejun Heo do { 14518376fe22STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 14528376fe22STejun Heo } while (unlikely(ret == -EAGAIN)); 14538376fe22STejun Heo 14548376fe22STejun Heo if (likely(ret >= 0)) { 14558376fe22STejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 14568376fe22STejun Heo local_irq_restore(flags); 14578376fe22STejun Heo } 14588376fe22STejun Heo 14598376fe22STejun Heo /* -ENOENT from try_to_grab_pending() becomes %true */ 14608376fe22STejun Heo return ret; 14618376fe22STejun Heo } 14628376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work_on); 14638376fe22STejun Heo 14648376fe22STejun Heo /** 14658376fe22STejun Heo * mod_delayed_work - modify delay of or queue a delayed work 14668376fe22STejun Heo * @wq: workqueue to use 14678376fe22STejun Heo * @dwork: work to queue 14688376fe22STejun Heo * @delay: number of jiffies to wait before queueing 14698376fe22STejun Heo * 14708376fe22STejun Heo * mod_delayed_work_on() on local CPU. 14718376fe22STejun Heo */ 14728376fe22STejun Heo bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork, 14738376fe22STejun Heo unsigned long delay) 14748376fe22STejun Heo { 14758376fe22STejun Heo return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); 14768376fe22STejun Heo } 14778376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work); 14788376fe22STejun Heo 14798376fe22STejun Heo /** 1480c8e55f36STejun Heo * worker_enter_idle - enter idle state 1481c8e55f36STejun Heo * @worker: worker which is entering idle state 1482c8e55f36STejun Heo * 1483c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1484c8e55f36STejun Heo * necessary. 1485c8e55f36STejun Heo * 1486c8e55f36STejun Heo * LOCKING: 1487c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1488c8e55f36STejun Heo */ 1489c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 14901da177e4SLinus Torvalds { 1491bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1492c8e55f36STejun Heo 1493c8e55f36STejun Heo BUG_ON(worker->flags & WORKER_IDLE); 1494c8e55f36STejun Heo BUG_ON(!list_empty(&worker->entry) && 1495c8e55f36STejun Heo (worker->hentry.next || worker->hentry.pprev)); 1496c8e55f36STejun Heo 1497cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1498cb444766STejun Heo worker->flags |= WORKER_IDLE; 1499bd7bdd43STejun Heo pool->nr_idle++; 1500e22bee78STejun Heo worker->last_active = jiffies; 1501c8e55f36STejun Heo 1502c8e55f36STejun Heo /* idle_list is LIFO */ 1503bd7bdd43STejun Heo list_add(&worker->entry, &pool->idle_list); 1504db7bccf4STejun Heo 150563d95a91STejun Heo if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 1506628c78e7STejun Heo mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 1507cb444766STejun Heo 1508544ecf31STejun Heo /* 1509628c78e7STejun Heo * Sanity check nr_running. Because gcwq_unbind_fn() releases 1510628c78e7STejun Heo * gcwq->lock between setting %WORKER_UNBOUND and zapping 1511628c78e7STejun Heo * nr_running, the warning may trigger spuriously. Check iff 1512628c78e7STejun Heo * unbind is not in progress. 1513544ecf31STejun Heo */ 151424647570STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 1515bd7bdd43STejun Heo pool->nr_workers == pool->nr_idle && 151663d95a91STejun Heo atomic_read(get_pool_nr_running(pool))); 1517c8e55f36STejun Heo } 1518c8e55f36STejun Heo 1519c8e55f36STejun Heo /** 1520c8e55f36STejun Heo * worker_leave_idle - leave idle state 1521c8e55f36STejun Heo * @worker: worker which is leaving idle state 1522c8e55f36STejun Heo * 1523c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1524c8e55f36STejun Heo * 1525c8e55f36STejun Heo * LOCKING: 1526c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1527c8e55f36STejun Heo */ 1528c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1529c8e55f36STejun Heo { 1530bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1531c8e55f36STejun Heo 1532c8e55f36STejun Heo BUG_ON(!(worker->flags & WORKER_IDLE)); 1533d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1534bd7bdd43STejun Heo pool->nr_idle--; 1535c8e55f36STejun Heo list_del_init(&worker->entry); 1536c8e55f36STejun Heo } 1537c8e55f36STejun Heo 1538e22bee78STejun Heo /** 1539e22bee78STejun Heo * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq 1540e22bee78STejun Heo * @worker: self 1541e22bee78STejun Heo * 1542e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1543e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1544e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1545e22bee78STejun Heo * guaranteed to execute on the cpu. 1546e22bee78STejun Heo * 1547e22bee78STejun Heo * This function is to be used by rogue workers and rescuers to bind 1548e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1549e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1550e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1551e22bee78STejun Heo * verbatim as it's best effort and blocking and gcwq may be 1552e22bee78STejun Heo * [dis]associated in the meantime. 1553e22bee78STejun Heo * 1554f2d5a0eeSTejun Heo * This function tries set_cpus_allowed() and locks gcwq and verifies the 155524647570STejun Heo * binding against %POOL_DISASSOCIATED which is set during 1556f2d5a0eeSTejun Heo * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker 1557f2d5a0eeSTejun Heo * enters idle state or fetches works without dropping lock, it can 1558f2d5a0eeSTejun Heo * guarantee the scheduling requirement described in the first paragraph. 1559e22bee78STejun Heo * 1560e22bee78STejun Heo * CONTEXT: 1561e22bee78STejun Heo * Might sleep. Called without any lock but returns with gcwq->lock 1562e22bee78STejun Heo * held. 1563e22bee78STejun Heo * 1564e22bee78STejun Heo * RETURNS: 1565e22bee78STejun Heo * %true if the associated gcwq is online (@worker is successfully 1566e22bee78STejun Heo * bound), %false if offline. 1567e22bee78STejun Heo */ 1568e22bee78STejun Heo static bool worker_maybe_bind_and_lock(struct worker *worker) 1569972fa1c5SNamhyung Kim __acquires(&gcwq->lock) 1570e22bee78STejun Heo { 157124647570STejun Heo struct worker_pool *pool = worker->pool; 157224647570STejun Heo struct global_cwq *gcwq = pool->gcwq; 1573e22bee78STejun Heo struct task_struct *task = worker->task; 1574e22bee78STejun Heo 1575e22bee78STejun Heo while (true) { 1576e22bee78STejun Heo /* 1577e22bee78STejun Heo * The following call may fail, succeed or succeed 1578e22bee78STejun Heo * without actually migrating the task to the cpu if 1579e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 158024647570STejun Heo * against POOL_DISASSOCIATED. 1581e22bee78STejun Heo */ 158224647570STejun Heo if (!(pool->flags & POOL_DISASSOCIATED)) 1583e22bee78STejun Heo set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); 1584e22bee78STejun Heo 1585e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 158624647570STejun Heo if (pool->flags & POOL_DISASSOCIATED) 1587e22bee78STejun Heo return false; 1588e22bee78STejun Heo if (task_cpu(task) == gcwq->cpu && 1589e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1590e22bee78STejun Heo get_cpu_mask(gcwq->cpu))) 1591e22bee78STejun Heo return true; 1592e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1593e22bee78STejun Heo 15945035b20fSTejun Heo /* 15955035b20fSTejun Heo * We've raced with CPU hot[un]plug. Give it a breather 15965035b20fSTejun Heo * and retry migration. cond_resched() is required here; 15975035b20fSTejun Heo * otherwise, we might deadlock against cpu_stop trying to 15985035b20fSTejun Heo * bring down the CPU on non-preemptive kernel. 15995035b20fSTejun Heo */ 1600e22bee78STejun Heo cpu_relax(); 16015035b20fSTejun Heo cond_resched(); 1602e22bee78STejun Heo } 1603e22bee78STejun Heo } 1604e22bee78STejun Heo 1605e22bee78STejun Heo /* 1606ea1abd61SLai Jiangshan * Rebind an idle @worker to its CPU. worker_thread() will test 16075f7dabfdSLai Jiangshan * list_empty(@worker->entry) before leaving idle and call this function. 160825511a47STejun Heo */ 160925511a47STejun Heo static void idle_worker_rebind(struct worker *worker) 161025511a47STejun Heo { 161125511a47STejun Heo struct global_cwq *gcwq = worker->pool->gcwq; 161225511a47STejun Heo 16135f7dabfdSLai Jiangshan /* CPU may go down again inbetween, clear UNBOUND only on success */ 16145f7dabfdSLai Jiangshan if (worker_maybe_bind_and_lock(worker)) 16155f7dabfdSLai Jiangshan worker_clr_flags(worker, WORKER_UNBOUND); 161625511a47STejun Heo 1617ea1abd61SLai Jiangshan /* rebind complete, become available again */ 1618ea1abd61SLai Jiangshan list_add(&worker->entry, &worker->pool->idle_list); 1619ea1abd61SLai Jiangshan spin_unlock_irq(&gcwq->lock); 162025511a47STejun Heo } 162125511a47STejun Heo 162225511a47STejun Heo /* 162325511a47STejun Heo * Function for @worker->rebind.work used to rebind unbound busy workers to 1624403c821dSTejun Heo * the associated cpu which is coming back online. This is scheduled by 1625403c821dSTejun Heo * cpu up but can race with other cpu hotplug operations and may be 1626403c821dSTejun Heo * executed twice without intervening cpu down. 1627e22bee78STejun Heo */ 162825511a47STejun Heo static void busy_worker_rebind_fn(struct work_struct *work) 1629e22bee78STejun Heo { 1630e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1631bd7bdd43STejun Heo struct global_cwq *gcwq = worker->pool->gcwq; 1632e22bee78STejun Heo 1633eab6d828SLai Jiangshan if (worker_maybe_bind_and_lock(worker)) 1634eab6d828SLai Jiangshan worker_clr_flags(worker, WORKER_UNBOUND); 1635e22bee78STejun Heo 1636e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1637e22bee78STejun Heo } 1638e22bee78STejun Heo 163925511a47STejun Heo /** 164025511a47STejun Heo * rebind_workers - rebind all workers of a gcwq to the associated CPU 164125511a47STejun Heo * @gcwq: gcwq of interest 164225511a47STejun Heo * 164325511a47STejun Heo * @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding 164425511a47STejun Heo * is different for idle and busy ones. 164525511a47STejun Heo * 1646ea1abd61SLai Jiangshan * Idle ones will be removed from the idle_list and woken up. They will 1647ea1abd61SLai Jiangshan * add themselves back after completing rebind. This ensures that the 1648ea1abd61SLai Jiangshan * idle_list doesn't contain any unbound workers when re-bound busy workers 1649ea1abd61SLai Jiangshan * try to perform local wake-ups for concurrency management. 165025511a47STejun Heo * 1651ea1abd61SLai Jiangshan * Busy workers can rebind after they finish their current work items. 1652ea1abd61SLai Jiangshan * Queueing the rebind work item at the head of the scheduled list is 1653ea1abd61SLai Jiangshan * enough. Note that nr_running will be properly bumped as busy workers 1654ea1abd61SLai Jiangshan * rebind. 165525511a47STejun Heo * 1656ea1abd61SLai Jiangshan * On return, all non-manager workers are scheduled for rebind - see 1657ea1abd61SLai Jiangshan * manage_workers() for the manager special case. Any idle worker 1658ea1abd61SLai Jiangshan * including the manager will not appear on @idle_list until rebind is 1659ea1abd61SLai Jiangshan * complete, making local wake-ups safe. 166025511a47STejun Heo */ 166125511a47STejun Heo static void rebind_workers(struct global_cwq *gcwq) 166225511a47STejun Heo { 166325511a47STejun Heo struct worker_pool *pool; 1664ea1abd61SLai Jiangshan struct worker *worker, *n; 166525511a47STejun Heo struct hlist_node *pos; 166625511a47STejun Heo int i; 166725511a47STejun Heo 166825511a47STejun Heo lockdep_assert_held(&gcwq->lock); 166925511a47STejun Heo 167025511a47STejun Heo for_each_worker_pool(pool, gcwq) 1671b2eb83d1SLai Jiangshan lockdep_assert_held(&pool->assoc_mutex); 167225511a47STejun Heo 16735f7dabfdSLai Jiangshan /* dequeue and kick idle ones */ 167425511a47STejun Heo for_each_worker_pool(pool, gcwq) { 1675ea1abd61SLai Jiangshan list_for_each_entry_safe(worker, n, &pool->idle_list, entry) { 1676ea1abd61SLai Jiangshan /* 1677ea1abd61SLai Jiangshan * idle workers should be off @pool->idle_list 1678ea1abd61SLai Jiangshan * until rebind is complete to avoid receiving 1679ea1abd61SLai Jiangshan * premature local wake-ups. 1680ea1abd61SLai Jiangshan */ 1681ea1abd61SLai Jiangshan list_del_init(&worker->entry); 168225511a47STejun Heo 168325511a47STejun Heo /* 16845f7dabfdSLai Jiangshan * worker_thread() will see the above dequeuing 16855f7dabfdSLai Jiangshan * and call idle_worker_rebind(). 168625511a47STejun Heo */ 168725511a47STejun Heo wake_up_process(worker->task); 168825511a47STejun Heo } 168925511a47STejun Heo } 169025511a47STejun Heo 1691ea1abd61SLai Jiangshan /* rebind busy workers */ 169225511a47STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 169325511a47STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 1694e2b6a6d5SJoonsoo Kim struct workqueue_struct *wq; 169525511a47STejun Heo 169625511a47STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 169725511a47STejun Heo work_data_bits(rebind_work))) 169825511a47STejun Heo continue; 169925511a47STejun Heo 170025511a47STejun Heo debug_work_activate(rebind_work); 170190beca5dSTejun Heo 170290beca5dSTejun Heo /* 1703e2b6a6d5SJoonsoo Kim * wq doesn't really matter but let's keep @worker->pool 1704e2b6a6d5SJoonsoo Kim * and @cwq->pool consistent for sanity. 170590beca5dSTejun Heo */ 1706e34cdddbSTejun Heo if (std_worker_pool_pri(worker->pool)) 1707e2b6a6d5SJoonsoo Kim wq = system_highpri_wq; 1708e2b6a6d5SJoonsoo Kim else 1709e2b6a6d5SJoonsoo Kim wq = system_wq; 1710ec58815aSTejun Heo 1711e2b6a6d5SJoonsoo Kim insert_work(get_cwq(gcwq->cpu, wq), rebind_work, 171225511a47STejun Heo worker->scheduled.next, 171325511a47STejun Heo work_color_to_flags(WORK_NO_COLOR)); 1714ec58815aSTejun Heo } 171525511a47STejun Heo } 171625511a47STejun Heo 1717c34056a3STejun Heo static struct worker *alloc_worker(void) 1718c34056a3STejun Heo { 1719c34056a3STejun Heo struct worker *worker; 1720c34056a3STejun Heo 1721c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1722c8e55f36STejun Heo if (worker) { 1723c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1724affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 172525511a47STejun Heo INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn); 1726e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1727e22bee78STejun Heo worker->flags = WORKER_PREP; 1728c8e55f36STejun Heo } 1729c34056a3STejun Heo return worker; 1730c34056a3STejun Heo } 1731c34056a3STejun Heo 1732c34056a3STejun Heo /** 1733c34056a3STejun Heo * create_worker - create a new workqueue worker 173463d95a91STejun Heo * @pool: pool the new worker will belong to 1735c34056a3STejun Heo * 173663d95a91STejun Heo * Create a new worker which is bound to @pool. The returned worker 1737c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1738c34056a3STejun Heo * destroy_worker(). 1739c34056a3STejun Heo * 1740c34056a3STejun Heo * CONTEXT: 1741c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1742c34056a3STejun Heo * 1743c34056a3STejun Heo * RETURNS: 1744c34056a3STejun Heo * Pointer to the newly created worker. 1745c34056a3STejun Heo */ 1746bc2ae0f5STejun Heo static struct worker *create_worker(struct worker_pool *pool) 1747c34056a3STejun Heo { 174863d95a91STejun Heo struct global_cwq *gcwq = pool->gcwq; 1749e34cdddbSTejun Heo const char *pri = std_worker_pool_pri(pool) ? "H" : ""; 1750c34056a3STejun Heo struct worker *worker = NULL; 1751f3421797STejun Heo int id = -1; 1752c34056a3STejun Heo 17538b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1754bd7bdd43STejun Heo while (ida_get_new(&pool->worker_ida, &id)) { 17558b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1756bd7bdd43STejun Heo if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL)) 1757c34056a3STejun Heo goto fail; 17588b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1759c34056a3STejun Heo } 17608b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1761c34056a3STejun Heo 1762c34056a3STejun Heo worker = alloc_worker(); 1763c34056a3STejun Heo if (!worker) 1764c34056a3STejun Heo goto fail; 1765c34056a3STejun Heo 1766bd7bdd43STejun Heo worker->pool = pool; 1767c34056a3STejun Heo worker->id = id; 1768c34056a3STejun Heo 1769bc2ae0f5STejun Heo if (gcwq->cpu != WORK_CPU_UNBOUND) 177094dcf29aSEric Dumazet worker->task = kthread_create_on_node(worker_thread, 17713270476aSTejun Heo worker, cpu_to_node(gcwq->cpu), 17723270476aSTejun Heo "kworker/%u:%d%s", gcwq->cpu, id, pri); 1773f3421797STejun Heo else 1774f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 17753270476aSTejun Heo "kworker/u:%d%s", id, pri); 1776c34056a3STejun Heo if (IS_ERR(worker->task)) 1777c34056a3STejun Heo goto fail; 1778c34056a3STejun Heo 1779e34cdddbSTejun Heo if (std_worker_pool_pri(pool)) 17803270476aSTejun Heo set_user_nice(worker->task, HIGHPRI_NICE_LEVEL); 17813270476aSTejun Heo 1782db7bccf4STejun Heo /* 1783bc2ae0f5STejun Heo * Determine CPU binding of the new worker depending on 178424647570STejun Heo * %POOL_DISASSOCIATED. The caller is responsible for ensuring the 1785bc2ae0f5STejun Heo * flag remains stable across this function. See the comments 1786bc2ae0f5STejun Heo * above the flag definition for details. 1787bc2ae0f5STejun Heo * 1788bc2ae0f5STejun Heo * As an unbound worker may later become a regular one if CPU comes 1789bc2ae0f5STejun Heo * online, make sure every worker has %PF_THREAD_BOUND set. 1790db7bccf4STejun Heo */ 179124647570STejun Heo if (!(pool->flags & POOL_DISASSOCIATED)) { 17928b03ae3cSTejun Heo kthread_bind(worker->task, gcwq->cpu); 1793bc2ae0f5STejun Heo } else { 1794db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1795f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1796f3421797STejun Heo } 1797c34056a3STejun Heo 1798c34056a3STejun Heo return worker; 1799c34056a3STejun Heo fail: 1800c34056a3STejun Heo if (id >= 0) { 18018b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1802bd7bdd43STejun Heo ida_remove(&pool->worker_ida, id); 18038b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1804c34056a3STejun Heo } 1805c34056a3STejun Heo kfree(worker); 1806c34056a3STejun Heo return NULL; 1807c34056a3STejun Heo } 1808c34056a3STejun Heo 1809c34056a3STejun Heo /** 1810c34056a3STejun Heo * start_worker - start a newly created worker 1811c34056a3STejun Heo * @worker: worker to start 1812c34056a3STejun Heo * 1813c8e55f36STejun Heo * Make the gcwq aware of @worker and start it. 1814c34056a3STejun Heo * 1815c34056a3STejun Heo * CONTEXT: 18168b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1817c34056a3STejun Heo */ 1818c34056a3STejun Heo static void start_worker(struct worker *worker) 1819c34056a3STejun Heo { 1820cb444766STejun Heo worker->flags |= WORKER_STARTED; 1821bd7bdd43STejun Heo worker->pool->nr_workers++; 1822c8e55f36STejun Heo worker_enter_idle(worker); 1823c34056a3STejun Heo wake_up_process(worker->task); 1824c34056a3STejun Heo } 1825c34056a3STejun Heo 1826c34056a3STejun Heo /** 1827c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1828c34056a3STejun Heo * @worker: worker to be destroyed 1829c34056a3STejun Heo * 1830c8e55f36STejun Heo * Destroy @worker and adjust @gcwq stats accordingly. 1831c8e55f36STejun Heo * 1832c8e55f36STejun Heo * CONTEXT: 1833c8e55f36STejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1834c34056a3STejun Heo */ 1835c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1836c34056a3STejun Heo { 1837bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1838bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 1839c34056a3STejun Heo int id = worker->id; 1840c34056a3STejun Heo 1841c34056a3STejun Heo /* sanity check frenzy */ 1842c34056a3STejun Heo BUG_ON(worker->current_work); 1843affee4b2STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1844c34056a3STejun Heo 1845c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1846bd7bdd43STejun Heo pool->nr_workers--; 1847c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1848bd7bdd43STejun Heo pool->nr_idle--; 1849c8e55f36STejun Heo 1850c8e55f36STejun Heo list_del_init(&worker->entry); 1851cb444766STejun Heo worker->flags |= WORKER_DIE; 1852c8e55f36STejun Heo 1853c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1854c8e55f36STejun Heo 1855c34056a3STejun Heo kthread_stop(worker->task); 1856c34056a3STejun Heo kfree(worker); 1857c34056a3STejun Heo 18588b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1859bd7bdd43STejun Heo ida_remove(&pool->worker_ida, id); 1860c34056a3STejun Heo } 1861c34056a3STejun Heo 186263d95a91STejun Heo static void idle_worker_timeout(unsigned long __pool) 1863e22bee78STejun Heo { 186463d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 186563d95a91STejun Heo struct global_cwq *gcwq = pool->gcwq; 1866e22bee78STejun Heo 1867e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1868e22bee78STejun Heo 186963d95a91STejun Heo if (too_many_workers(pool)) { 1870e22bee78STejun Heo struct worker *worker; 1871e22bee78STejun Heo unsigned long expires; 1872e22bee78STejun Heo 1873e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 187463d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 1875e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1876e22bee78STejun Heo 1877e22bee78STejun Heo if (time_before(jiffies, expires)) 187863d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 1879e22bee78STejun Heo else { 1880e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 188111ebea50STejun Heo pool->flags |= POOL_MANAGE_WORKERS; 188263d95a91STejun Heo wake_up_worker(pool); 1883e22bee78STejun Heo } 1884e22bee78STejun Heo } 1885e22bee78STejun Heo 1886e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1887e22bee78STejun Heo } 1888e22bee78STejun Heo 1889e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1890e22bee78STejun Heo { 1891e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1892e22bee78STejun Heo struct workqueue_struct *wq = cwq->wq; 1893f3421797STejun Heo unsigned int cpu; 1894e22bee78STejun Heo 1895e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1896e22bee78STejun Heo return false; 1897e22bee78STejun Heo 1898e22bee78STejun Heo /* mayday mayday mayday */ 1899bd7bdd43STejun Heo cpu = cwq->pool->gcwq->cpu; 1900f3421797STejun Heo /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1901f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 1902f3421797STejun Heo cpu = 0; 1903f2e005aaSTejun Heo if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) 1904e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1905e22bee78STejun Heo return true; 1906e22bee78STejun Heo } 1907e22bee78STejun Heo 190863d95a91STejun Heo static void gcwq_mayday_timeout(unsigned long __pool) 1909e22bee78STejun Heo { 191063d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 191163d95a91STejun Heo struct global_cwq *gcwq = pool->gcwq; 1912e22bee78STejun Heo struct work_struct *work; 1913e22bee78STejun Heo 1914e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1915e22bee78STejun Heo 191663d95a91STejun Heo if (need_to_create_worker(pool)) { 1917e22bee78STejun Heo /* 1918e22bee78STejun Heo * We've been trying to create a new worker but 1919e22bee78STejun Heo * haven't been successful. We might be hitting an 1920e22bee78STejun Heo * allocation deadlock. Send distress signals to 1921e22bee78STejun Heo * rescuers. 1922e22bee78STejun Heo */ 192363d95a91STejun Heo list_for_each_entry(work, &pool->worklist, entry) 1924e22bee78STejun Heo send_mayday(work); 1925e22bee78STejun Heo } 1926e22bee78STejun Heo 1927e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1928e22bee78STejun Heo 192963d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 1930e22bee78STejun Heo } 1931e22bee78STejun Heo 1932e22bee78STejun Heo /** 1933e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 193463d95a91STejun Heo * @pool: pool to create a new worker for 1935e22bee78STejun Heo * 193663d95a91STejun Heo * Create a new worker for @pool if necessary. @pool is guaranteed to 1937e22bee78STejun Heo * have at least one idle worker on return from this function. If 1938e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 193963d95a91STejun Heo * sent to all rescuers with works scheduled on @pool to resolve 1940e22bee78STejun Heo * possible allocation deadlock. 1941e22bee78STejun Heo * 1942e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1943e22bee78STejun Heo * may_start_working() true. 1944e22bee78STejun Heo * 1945e22bee78STejun Heo * LOCKING: 1946e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1947e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1948e22bee78STejun Heo * manager. 1949e22bee78STejun Heo * 1950e22bee78STejun Heo * RETURNS: 1951e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1952e22bee78STejun Heo * otherwise. 1953e22bee78STejun Heo */ 195463d95a91STejun Heo static bool maybe_create_worker(struct worker_pool *pool) 195506bd6ebfSNamhyung Kim __releases(&gcwq->lock) 195606bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 1957e22bee78STejun Heo { 195863d95a91STejun Heo struct global_cwq *gcwq = pool->gcwq; 195963d95a91STejun Heo 196063d95a91STejun Heo if (!need_to_create_worker(pool)) 1961e22bee78STejun Heo return false; 1962e22bee78STejun Heo restart: 19639f9c2364STejun Heo spin_unlock_irq(&gcwq->lock); 19649f9c2364STejun Heo 1965e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 196663d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1967e22bee78STejun Heo 1968e22bee78STejun Heo while (true) { 1969e22bee78STejun Heo struct worker *worker; 1970e22bee78STejun Heo 1971bc2ae0f5STejun Heo worker = create_worker(pool); 1972e22bee78STejun Heo if (worker) { 197363d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 1974e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1975e22bee78STejun Heo start_worker(worker); 197663d95a91STejun Heo BUG_ON(need_to_create_worker(pool)); 1977e22bee78STejun Heo return true; 1978e22bee78STejun Heo } 1979e22bee78STejun Heo 198063d95a91STejun Heo if (!need_to_create_worker(pool)) 1981e22bee78STejun Heo break; 1982e22bee78STejun Heo 1983e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1984e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 19859f9c2364STejun Heo 198663d95a91STejun Heo if (!need_to_create_worker(pool)) 1987e22bee78STejun Heo break; 1988e22bee78STejun Heo } 1989e22bee78STejun Heo 199063d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 1991e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 199263d95a91STejun Heo if (need_to_create_worker(pool)) 1993e22bee78STejun Heo goto restart; 1994e22bee78STejun Heo return true; 1995e22bee78STejun Heo } 1996e22bee78STejun Heo 1997e22bee78STejun Heo /** 1998e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 199963d95a91STejun Heo * @pool: pool to destroy workers for 2000e22bee78STejun Heo * 200163d95a91STejun Heo * Destroy @pool workers which have been idle for longer than 2002e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 2003e22bee78STejun Heo * 2004e22bee78STejun Heo * LOCKING: 2005e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2006e22bee78STejun Heo * multiple times. Called only from manager. 2007e22bee78STejun Heo * 2008e22bee78STejun Heo * RETURNS: 2009e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 2010e22bee78STejun Heo * otherwise. 2011e22bee78STejun Heo */ 201263d95a91STejun Heo static bool maybe_destroy_workers(struct worker_pool *pool) 2013e22bee78STejun Heo { 2014e22bee78STejun Heo bool ret = false; 2015e22bee78STejun Heo 201663d95a91STejun Heo while (too_many_workers(pool)) { 2017e22bee78STejun Heo struct worker *worker; 2018e22bee78STejun Heo unsigned long expires; 2019e22bee78STejun Heo 202063d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 2021e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 2022e22bee78STejun Heo 2023e22bee78STejun Heo if (time_before(jiffies, expires)) { 202463d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 2025e22bee78STejun Heo break; 2026e22bee78STejun Heo } 2027e22bee78STejun Heo 2028e22bee78STejun Heo destroy_worker(worker); 2029e22bee78STejun Heo ret = true; 2030e22bee78STejun Heo } 2031e22bee78STejun Heo 2032e22bee78STejun Heo return ret; 2033e22bee78STejun Heo } 2034e22bee78STejun Heo 2035e22bee78STejun Heo /** 2036e22bee78STejun Heo * manage_workers - manage worker pool 2037e22bee78STejun Heo * @worker: self 2038e22bee78STejun Heo * 2039e22bee78STejun Heo * Assume the manager role and manage gcwq worker pool @worker belongs 2040e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 2041e22bee78STejun Heo * gcwq. The exclusion is handled automatically by this function. 2042e22bee78STejun Heo * 2043e22bee78STejun Heo * The caller can safely start processing works on false return. On 2044e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 2045e22bee78STejun Heo * and may_start_working() is true. 2046e22bee78STejun Heo * 2047e22bee78STejun Heo * CONTEXT: 2048e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2049e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 2050e22bee78STejun Heo * 2051e22bee78STejun Heo * RETURNS: 2052e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true if 2053e22bee78STejun Heo * some action was taken. 2054e22bee78STejun Heo */ 2055e22bee78STejun Heo static bool manage_workers(struct worker *worker) 2056e22bee78STejun Heo { 205763d95a91STejun Heo struct worker_pool *pool = worker->pool; 2058e22bee78STejun Heo bool ret = false; 2059e22bee78STejun Heo 2060ee378aa4SLai Jiangshan if (pool->flags & POOL_MANAGING_WORKERS) 2061e22bee78STejun Heo return ret; 2062e22bee78STejun Heo 2063552a37e9SLai Jiangshan pool->flags |= POOL_MANAGING_WORKERS; 2064ee378aa4SLai Jiangshan 2065ee378aa4SLai Jiangshan /* 2066ee378aa4SLai Jiangshan * To simplify both worker management and CPU hotplug, hold off 2067ee378aa4SLai Jiangshan * management while hotplug is in progress. CPU hotplug path can't 2068ee378aa4SLai Jiangshan * grab %POOL_MANAGING_WORKERS to achieve this because that can 2069ee378aa4SLai Jiangshan * lead to idle worker depletion (all become busy thinking someone 2070ee378aa4SLai Jiangshan * else is managing) which in turn can result in deadlock under 2071b2eb83d1SLai Jiangshan * extreme circumstances. Use @pool->assoc_mutex to synchronize 2072ee378aa4SLai Jiangshan * manager against CPU hotplug. 2073ee378aa4SLai Jiangshan * 2074b2eb83d1SLai Jiangshan * assoc_mutex would always be free unless CPU hotplug is in 2075ee378aa4SLai Jiangshan * progress. trylock first without dropping @gcwq->lock. 2076ee378aa4SLai Jiangshan */ 2077b2eb83d1SLai Jiangshan if (unlikely(!mutex_trylock(&pool->assoc_mutex))) { 2078ee378aa4SLai Jiangshan spin_unlock_irq(&pool->gcwq->lock); 2079b2eb83d1SLai Jiangshan mutex_lock(&pool->assoc_mutex); 2080ee378aa4SLai Jiangshan /* 2081ee378aa4SLai Jiangshan * CPU hotplug could have happened while we were waiting 2082b2eb83d1SLai Jiangshan * for assoc_mutex. Hotplug itself can't handle us 2083ee378aa4SLai Jiangshan * because manager isn't either on idle or busy list, and 2084ee378aa4SLai Jiangshan * @gcwq's state and ours could have deviated. 2085ee378aa4SLai Jiangshan * 2086b2eb83d1SLai Jiangshan * As hotplug is now excluded via assoc_mutex, we can 2087ee378aa4SLai Jiangshan * simply try to bind. It will succeed or fail depending 2088ee378aa4SLai Jiangshan * on @gcwq's current state. Try it and adjust 2089ee378aa4SLai Jiangshan * %WORKER_UNBOUND accordingly. 2090ee378aa4SLai Jiangshan */ 2091ee378aa4SLai Jiangshan if (worker_maybe_bind_and_lock(worker)) 2092ee378aa4SLai Jiangshan worker->flags &= ~WORKER_UNBOUND; 2093ee378aa4SLai Jiangshan else 2094ee378aa4SLai Jiangshan worker->flags |= WORKER_UNBOUND; 2095ee378aa4SLai Jiangshan 2096ee378aa4SLai Jiangshan ret = true; 2097ee378aa4SLai Jiangshan } 2098ee378aa4SLai Jiangshan 209911ebea50STejun Heo pool->flags &= ~POOL_MANAGE_WORKERS; 2100e22bee78STejun Heo 2101e22bee78STejun Heo /* 2102e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 2103e22bee78STejun Heo * on return. 2104e22bee78STejun Heo */ 210563d95a91STejun Heo ret |= maybe_destroy_workers(pool); 210663d95a91STejun Heo ret |= maybe_create_worker(pool); 2107e22bee78STejun Heo 2108552a37e9SLai Jiangshan pool->flags &= ~POOL_MANAGING_WORKERS; 2109b2eb83d1SLai Jiangshan mutex_unlock(&pool->assoc_mutex); 2110e22bee78STejun Heo return ret; 2111e22bee78STejun Heo } 2112e22bee78STejun Heo 2113a62428c0STejun Heo /** 2114a62428c0STejun Heo * process_one_work - process single work 2115c34056a3STejun Heo * @worker: self 2116a62428c0STejun Heo * @work: work to process 2117a62428c0STejun Heo * 2118a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 2119a62428c0STejun Heo * process a single work including synchronization against and 2120a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 2121a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 2122a62428c0STejun Heo * call this function to process a work. 2123a62428c0STejun Heo * 2124a62428c0STejun Heo * CONTEXT: 21258b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 2126a62428c0STejun Heo */ 2127c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 212806bd6ebfSNamhyung Kim __releases(&gcwq->lock) 212906bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 21301da177e4SLinus Torvalds { 21317e11629dSTejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 2132bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2133bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 2134fb0e7bebSTejun Heo bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 213573f53c4aSTejun Heo int work_color; 21367e11629dSTejun Heo struct worker *collision; 21374e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 21384e6045f1SJohannes Berg /* 2139a62428c0STejun Heo * It is permissible to free the struct work_struct from 2140a62428c0STejun Heo * inside the function that is called from it, this we need to 2141a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 2142a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 2143a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 21444e6045f1SJohannes Berg */ 21454d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 21464d82a1deSPeter Zijlstra 21474d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 21484e6045f1SJohannes Berg #endif 21496fec10a1STejun Heo /* 21506fec10a1STejun Heo * Ensure we're on the correct CPU. DISASSOCIATED test is 21516fec10a1STejun Heo * necessary to avoid spurious warnings from rescuers servicing the 215224647570STejun Heo * unbound or a disassociated pool. 21536fec10a1STejun Heo */ 21545f7dabfdSLai Jiangshan WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && 215524647570STejun Heo !(pool->flags & POOL_DISASSOCIATED) && 215625511a47STejun Heo raw_smp_processor_id() != gcwq->cpu); 215725511a47STejun Heo 21587e11629dSTejun Heo /* 21597e11629dSTejun Heo * A single work shouldn't be executed concurrently by 21607e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 21617e11629dSTejun Heo * already processing the work. If so, defer the work to the 21627e11629dSTejun Heo * currently executing one. 21637e11629dSTejun Heo */ 216442f8570fSSasha Levin collision = find_worker_executing_work(gcwq, work); 21657e11629dSTejun Heo if (unlikely(collision)) { 21667e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 21677e11629dSTejun Heo return; 21687e11629dSTejun Heo } 21691da177e4SLinus Torvalds 21708930cabaSTejun Heo /* claim and dequeue */ 21711da177e4SLinus Torvalds debug_work_deactivate(work); 2172023f27d3STejun Heo hash_add(gcwq->busy_hash, &worker->hentry, (unsigned long)work); 2173c34056a3STejun Heo worker->current_work = work; 2174a2c1c57bSTejun Heo worker->current_func = work->func; 21758cca0eeaSTejun Heo worker->current_cwq = cwq; 217673f53c4aSTejun Heo work_color = get_work_color(work); 21777a22ad75STejun Heo 2178a62428c0STejun Heo list_del_init(&work->entry); 2179a62428c0STejun Heo 2180649027d7STejun Heo /* 2181fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 2182fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 2183fb0e7bebSTejun Heo */ 2184fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2185fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 2186fb0e7bebSTejun Heo 2187974271c4STejun Heo /* 2188974271c4STejun Heo * Unbound gcwq isn't concurrency managed and work items should be 2189974271c4STejun Heo * executed ASAP. Wake up another worker if necessary. 2190974271c4STejun Heo */ 219163d95a91STejun Heo if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) 219263d95a91STejun Heo wake_up_worker(pool); 2193974271c4STejun Heo 21948930cabaSTejun Heo /* 219523657bb1STejun Heo * Record the last CPU and clear PENDING which should be the last 219623657bb1STejun Heo * update to @work. Also, do this inside @gcwq->lock so that 219723657bb1STejun Heo * PENDING and queued state changes happen together while IRQ is 219823657bb1STejun Heo * disabled. 21998930cabaSTejun Heo */ 22008930cabaSTejun Heo set_work_cpu_and_clear_pending(work, gcwq->cpu); 22011da177e4SLinus Torvalds 22021da177e4SLinus Torvalds spin_unlock_irq(&gcwq->lock); 2203365970a1SDavid Howells 2204e159489bSTejun Heo lock_map_acquire_read(&cwq->wq->lockdep_map); 22053295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 2206e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 2207a2c1c57bSTejun Heo worker->current_func(work); 2208e36c886aSArjan van de Ven /* 2209e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 2210e36c886aSArjan van de Ven * point will only record its address. 2211e36c886aSArjan van de Ven */ 2212e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 22133295f0efSIngo Molnar lock_map_release(&lockdep_map); 22143295f0efSIngo Molnar lock_map_release(&cwq->wq->lockdep_map); 22151da177e4SLinus Torvalds 2216d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 2217044c782cSValentin Ilie pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" 2218044c782cSValentin Ilie " last function: %pf\n", 2219a2c1c57bSTejun Heo current->comm, preempt_count(), task_pid_nr(current), 2220a2c1c57bSTejun Heo worker->current_func); 2221d5abe669SPeter Zijlstra debug_show_held_locks(current); 2222d5abe669SPeter Zijlstra dump_stack(); 2223d5abe669SPeter Zijlstra } 2224d5abe669SPeter Zijlstra 22258b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2226a62428c0STejun Heo 2227fb0e7bebSTejun Heo /* clear cpu intensive status */ 2228fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2229fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 2230fb0e7bebSTejun Heo 2231a62428c0STejun Heo /* we're done with it, release */ 223242f8570fSSasha Levin hash_del(&worker->hentry); 2233c34056a3STejun Heo worker->current_work = NULL; 2234a2c1c57bSTejun Heo worker->current_func = NULL; 22358cca0eeaSTejun Heo worker->current_cwq = NULL; 2236b3f9f405SLai Jiangshan cwq_dec_nr_in_flight(cwq, work_color); 22371da177e4SLinus Torvalds } 22381da177e4SLinus Torvalds 2239affee4b2STejun Heo /** 2240affee4b2STejun Heo * process_scheduled_works - process scheduled works 2241affee4b2STejun Heo * @worker: self 2242affee4b2STejun Heo * 2243affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 2244affee4b2STejun Heo * may change while processing a work, so this function repeatedly 2245affee4b2STejun Heo * fetches a work from the top and executes it. 2246affee4b2STejun Heo * 2247affee4b2STejun Heo * CONTEXT: 22488b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2249affee4b2STejun Heo * multiple times. 2250affee4b2STejun Heo */ 2251affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 22521da177e4SLinus Torvalds { 2253affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 2254affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 2255a62428c0STejun Heo struct work_struct, entry); 2256c34056a3STejun Heo process_one_work(worker, work); 2257a62428c0STejun Heo } 22581da177e4SLinus Torvalds } 22591da177e4SLinus Torvalds 22604690c4abSTejun Heo /** 22614690c4abSTejun Heo * worker_thread - the worker thread function 2262c34056a3STejun Heo * @__worker: self 22634690c4abSTejun Heo * 2264e22bee78STejun Heo * The gcwq worker thread function. There's a single dynamic pool of 2265e22bee78STejun Heo * these per each cpu. These workers process all works regardless of 2266e22bee78STejun Heo * their specific target workqueue. The only exception is works which 2267e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 2268e22bee78STejun Heo * rescuer_thread(). 22694690c4abSTejun Heo */ 2270c34056a3STejun Heo static int worker_thread(void *__worker) 22711da177e4SLinus Torvalds { 2272c34056a3STejun Heo struct worker *worker = __worker; 2273bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2274bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 22751da177e4SLinus Torvalds 2276e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 2277e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 2278c8e55f36STejun Heo woke_up: 22798b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2280affee4b2STejun Heo 22815f7dabfdSLai Jiangshan /* we are off idle list if destruction or rebind is requested */ 22825f7dabfdSLai Jiangshan if (unlikely(list_empty(&worker->entry))) { 2283c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 228425511a47STejun Heo 22855f7dabfdSLai Jiangshan /* if DIE is set, destruction is requested */ 228625511a47STejun Heo if (worker->flags & WORKER_DIE) { 2287e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 2288c8e55f36STejun Heo return 0; 2289c8e55f36STejun Heo } 2290c8e55f36STejun Heo 22915f7dabfdSLai Jiangshan /* otherwise, rebind */ 229225511a47STejun Heo idle_worker_rebind(worker); 229325511a47STejun Heo goto woke_up; 229425511a47STejun Heo } 229525511a47STejun Heo 2296c8e55f36STejun Heo worker_leave_idle(worker); 2297db7bccf4STejun Heo recheck: 2298e22bee78STejun Heo /* no more worker necessary? */ 229963d95a91STejun Heo if (!need_more_worker(pool)) 2300e22bee78STejun Heo goto sleep; 2301e22bee78STejun Heo 2302e22bee78STejun Heo /* do we need to manage? */ 230363d95a91STejun Heo if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 2304e22bee78STejun Heo goto recheck; 2305e22bee78STejun Heo 2306c8e55f36STejun Heo /* 2307c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 2308c8e55f36STejun Heo * preparing to process a work or actually processing it. 2309c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 2310c8e55f36STejun Heo */ 2311c8e55f36STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 2312c8e55f36STejun Heo 2313e22bee78STejun Heo /* 2314e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 2315e22bee78STejun Heo * at least one idle worker or that someone else has already 2316e22bee78STejun Heo * assumed the manager role. 2317e22bee78STejun Heo */ 2318e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 2319e22bee78STejun Heo 2320e22bee78STejun Heo do { 2321affee4b2STejun Heo struct work_struct *work = 2322bd7bdd43STejun Heo list_first_entry(&pool->worklist, 2323affee4b2STejun Heo struct work_struct, entry); 2324affee4b2STejun Heo 2325c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 2326affee4b2STejun Heo /* optimization path, not strictly necessary */ 2327affee4b2STejun Heo process_one_work(worker, work); 2328affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 2329affee4b2STejun Heo process_scheduled_works(worker); 2330affee4b2STejun Heo } else { 2331c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 2332affee4b2STejun Heo process_scheduled_works(worker); 2333affee4b2STejun Heo } 233463d95a91STejun Heo } while (keep_working(pool)); 2335affee4b2STejun Heo 2336e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 2337d313dd85STejun Heo sleep: 233863d95a91STejun Heo if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) 2339e22bee78STejun Heo goto recheck; 2340d313dd85STejun Heo 2341c8e55f36STejun Heo /* 2342e22bee78STejun Heo * gcwq->lock is held and there's no work to process and no 2343e22bee78STejun Heo * need to manage, sleep. Workers are woken up only while 2344e22bee78STejun Heo * holding gcwq->lock or from local cpu, so setting the 2345e22bee78STejun Heo * current state before releasing gcwq->lock is enough to 2346e22bee78STejun Heo * prevent losing any event. 2347c8e55f36STejun Heo */ 2348c8e55f36STejun Heo worker_enter_idle(worker); 2349c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 23508b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23511da177e4SLinus Torvalds schedule(); 2352c8e55f36STejun Heo goto woke_up; 23531da177e4SLinus Torvalds } 23541da177e4SLinus Torvalds 2355e22bee78STejun Heo /** 2356e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2357111c225aSTejun Heo * @__rescuer: self 2358e22bee78STejun Heo * 2359e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2360e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 2361e22bee78STejun Heo * 2362e22bee78STejun Heo * Regular work processing on a gcwq may block trying to create a new 2363e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2364e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2365e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2366e22bee78STejun Heo * the problem rescuer solves. 2367e22bee78STejun Heo * 2368e22bee78STejun Heo * When such condition is possible, the gcwq summons rescuers of all 2369e22bee78STejun Heo * workqueues which have works queued on the gcwq and let them process 2370e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2371e22bee78STejun Heo * 2372e22bee78STejun Heo * This should happen rarely. 2373e22bee78STejun Heo */ 2374111c225aSTejun Heo static int rescuer_thread(void *__rescuer) 2375e22bee78STejun Heo { 2376111c225aSTejun Heo struct worker *rescuer = __rescuer; 2377111c225aSTejun Heo struct workqueue_struct *wq = rescuer->rescue_wq; 2378e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 2379f3421797STejun Heo bool is_unbound = wq->flags & WQ_UNBOUND; 2380e22bee78STejun Heo unsigned int cpu; 2381e22bee78STejun Heo 2382e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2383111c225aSTejun Heo 2384111c225aSTejun Heo /* 2385111c225aSTejun Heo * Mark rescuer as worker too. As WORKER_PREP is never cleared, it 2386111c225aSTejun Heo * doesn't participate in concurrency management. 2387111c225aSTejun Heo */ 2388111c225aSTejun Heo rescuer->task->flags |= PF_WQ_WORKER; 2389e22bee78STejun Heo repeat: 2390e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 23911da177e4SLinus Torvalds 2392412d32e6SMike Galbraith if (kthread_should_stop()) { 2393412d32e6SMike Galbraith __set_current_state(TASK_RUNNING); 2394111c225aSTejun Heo rescuer->task->flags &= ~PF_WQ_WORKER; 2395e22bee78STejun Heo return 0; 2396412d32e6SMike Galbraith } 23971da177e4SLinus Torvalds 2398f3421797STejun Heo /* 2399f3421797STejun Heo * See whether any cpu is asking for help. Unbounded 2400f3421797STejun Heo * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. 2401f3421797STejun Heo */ 2402f2e005aaSTejun Heo for_each_mayday_cpu(cpu, wq->mayday_mask) { 2403f3421797STejun Heo unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 2404f3421797STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); 2405bd7bdd43STejun Heo struct worker_pool *pool = cwq->pool; 2406bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 2407e22bee78STejun Heo struct work_struct *work, *n; 2408e22bee78STejun Heo 2409e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2410f2e005aaSTejun Heo mayday_clear_cpu(cpu, wq->mayday_mask); 2411e22bee78STejun Heo 2412e22bee78STejun Heo /* migrate to the target cpu if possible */ 2413bd7bdd43STejun Heo rescuer->pool = pool; 2414e22bee78STejun Heo worker_maybe_bind_and_lock(rescuer); 2415e22bee78STejun Heo 2416e22bee78STejun Heo /* 2417e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2418e22bee78STejun Heo * process'em. 2419e22bee78STejun Heo */ 2420e22bee78STejun Heo BUG_ON(!list_empty(&rescuer->scheduled)); 2421bd7bdd43STejun Heo list_for_each_entry_safe(work, n, &pool->worklist, entry) 2422e22bee78STejun Heo if (get_work_cwq(work) == cwq) 2423e22bee78STejun Heo move_linked_works(work, scheduled, &n); 2424e22bee78STejun Heo 2425e22bee78STejun Heo process_scheduled_works(rescuer); 24267576958aSTejun Heo 24277576958aSTejun Heo /* 24287576958aSTejun Heo * Leave this gcwq. If keep_working() is %true, notify a 24297576958aSTejun Heo * regular worker; otherwise, we end up with 0 concurrency 24307576958aSTejun Heo * and stalling the execution. 24317576958aSTejun Heo */ 243263d95a91STejun Heo if (keep_working(pool)) 243363d95a91STejun Heo wake_up_worker(pool); 24347576958aSTejun Heo 2435e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 24361da177e4SLinus Torvalds } 24371da177e4SLinus Torvalds 2438111c225aSTejun Heo /* rescuers should never participate in concurrency management */ 2439111c225aSTejun Heo WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); 2440e22bee78STejun Heo schedule(); 2441e22bee78STejun Heo goto repeat; 24421da177e4SLinus Torvalds } 24431da177e4SLinus Torvalds 2444fc2e4d70SOleg Nesterov struct wq_barrier { 2445fc2e4d70SOleg Nesterov struct work_struct work; 2446fc2e4d70SOleg Nesterov struct completion done; 2447fc2e4d70SOleg Nesterov }; 2448fc2e4d70SOleg Nesterov 2449fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2450fc2e4d70SOleg Nesterov { 2451fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2452fc2e4d70SOleg Nesterov complete(&barr->done); 2453fc2e4d70SOleg Nesterov } 2454fc2e4d70SOleg Nesterov 24554690c4abSTejun Heo /** 24564690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 24574690c4abSTejun Heo * @cwq: cwq to insert barrier into 24584690c4abSTejun Heo * @barr: wq_barrier to insert 2459affee4b2STejun Heo * @target: target work to attach @barr to 2460affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 24614690c4abSTejun Heo * 2462affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2463affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2464affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2465affee4b2STejun Heo * cpu. 2466affee4b2STejun Heo * 2467affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2468affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2469affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2470affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2471affee4b2STejun Heo * after a work with LINKED flag set. 2472affee4b2STejun Heo * 2473affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2474affee4b2STejun Heo * underneath us, so we can't reliably determine cwq from @target. 24754690c4abSTejun Heo * 24764690c4abSTejun Heo * CONTEXT: 24778b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 24784690c4abSTejun Heo */ 247983c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 2480affee4b2STejun Heo struct wq_barrier *barr, 2481affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2482fc2e4d70SOleg Nesterov { 2483affee4b2STejun Heo struct list_head *head; 2484affee4b2STejun Heo unsigned int linked = 0; 2485affee4b2STejun Heo 2486dc186ad7SThomas Gleixner /* 24878b03ae3cSTejun Heo * debugobject calls are safe here even with gcwq->lock locked 2488dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2489dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2490dc186ad7SThomas Gleixner * might deadlock. 2491dc186ad7SThomas Gleixner */ 2492ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 249322df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2494fc2e4d70SOleg Nesterov init_completion(&barr->done); 249583c22520SOleg Nesterov 2496affee4b2STejun Heo /* 2497affee4b2STejun Heo * If @target is currently being executed, schedule the 2498affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2499affee4b2STejun Heo */ 2500affee4b2STejun Heo if (worker) 2501affee4b2STejun Heo head = worker->scheduled.next; 2502affee4b2STejun Heo else { 2503affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2504affee4b2STejun Heo 2505affee4b2STejun Heo head = target->entry.next; 2506affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2507affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2508affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2509affee4b2STejun Heo } 2510affee4b2STejun Heo 2511dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2512affee4b2STejun Heo insert_work(cwq, &barr->work, head, 2513affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2514fc2e4d70SOleg Nesterov } 2515fc2e4d70SOleg Nesterov 251673f53c4aSTejun Heo /** 251773f53c4aSTejun Heo * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing 251873f53c4aSTejun Heo * @wq: workqueue being flushed 251973f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 252073f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 252173f53c4aSTejun Heo * 252273f53c4aSTejun Heo * Prepare cwqs for workqueue flushing. 252373f53c4aSTejun Heo * 252473f53c4aSTejun Heo * If @flush_color is non-negative, flush_color on all cwqs should be 252573f53c4aSTejun Heo * -1. If no cwq has in-flight commands at the specified color, all 252673f53c4aSTejun Heo * cwq->flush_color's stay at -1 and %false is returned. If any cwq 252773f53c4aSTejun Heo * has in flight commands, its cwq->flush_color is set to 252873f53c4aSTejun Heo * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq 252973f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 253073f53c4aSTejun Heo * 253173f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 253273f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 253373f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 253473f53c4aSTejun Heo * is returned. 253573f53c4aSTejun Heo * 253673f53c4aSTejun Heo * If @work_color is non-negative, all cwqs should have the same 253773f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 253873f53c4aSTejun Heo * advanced to @work_color. 253973f53c4aSTejun Heo * 254073f53c4aSTejun Heo * CONTEXT: 254173f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 254273f53c4aSTejun Heo * 254373f53c4aSTejun Heo * RETURNS: 254473f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 254573f53c4aSTejun Heo * otherwise. 254673f53c4aSTejun Heo */ 254773f53c4aSTejun Heo static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, 254873f53c4aSTejun Heo int flush_color, int work_color) 25491da177e4SLinus Torvalds { 255073f53c4aSTejun Heo bool wait = false; 255173f53c4aSTejun Heo unsigned int cpu; 25521da177e4SLinus Torvalds 255373f53c4aSTejun Heo if (flush_color >= 0) { 255473f53c4aSTejun Heo BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); 255573f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 1); 2556dc186ad7SThomas Gleixner } 255714441960SOleg Nesterov 2558f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 255973f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2560bd7bdd43STejun Heo struct global_cwq *gcwq = cwq->pool->gcwq; 25611da177e4SLinus Torvalds 25628b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 256373f53c4aSTejun Heo 256473f53c4aSTejun Heo if (flush_color >= 0) { 256573f53c4aSTejun Heo BUG_ON(cwq->flush_color != -1); 256673f53c4aSTejun Heo 256773f53c4aSTejun Heo if (cwq->nr_in_flight[flush_color]) { 256873f53c4aSTejun Heo cwq->flush_color = flush_color; 256973f53c4aSTejun Heo atomic_inc(&wq->nr_cwqs_to_flush); 257073f53c4aSTejun Heo wait = true; 25711da177e4SLinus Torvalds } 257273f53c4aSTejun Heo } 257373f53c4aSTejun Heo 257473f53c4aSTejun Heo if (work_color >= 0) { 257573f53c4aSTejun Heo BUG_ON(work_color != work_next_color(cwq->work_color)); 257673f53c4aSTejun Heo cwq->work_color = work_color; 257773f53c4aSTejun Heo } 257873f53c4aSTejun Heo 25798b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 25801da177e4SLinus Torvalds } 25811da177e4SLinus Torvalds 258273f53c4aSTejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) 258373f53c4aSTejun Heo complete(&wq->first_flusher->done); 258473f53c4aSTejun Heo 258573f53c4aSTejun Heo return wait; 258683c22520SOleg Nesterov } 25871da177e4SLinus Torvalds 25880fcb78c2SRolf Eike Beer /** 25891da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 25900fcb78c2SRolf Eike Beer * @wq: workqueue to flush 25911da177e4SLinus Torvalds * 25921da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 25931da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 25941da177e4SLinus Torvalds * 2595fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2596fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 25971da177e4SLinus Torvalds */ 25987ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 25991da177e4SLinus Torvalds { 260073f53c4aSTejun Heo struct wq_flusher this_flusher = { 260173f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 260273f53c4aSTejun Heo .flush_color = -1, 260373f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 260473f53c4aSTejun Heo }; 260573f53c4aSTejun Heo int next_color; 2606b1f4ec17SOleg Nesterov 26073295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 26083295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 260973f53c4aSTejun Heo 261073f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 261173f53c4aSTejun Heo 261273f53c4aSTejun Heo /* 261373f53c4aSTejun Heo * Start-to-wait phase 261473f53c4aSTejun Heo */ 261573f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 261673f53c4aSTejun Heo 261773f53c4aSTejun Heo if (next_color != wq->flush_color) { 261873f53c4aSTejun Heo /* 261973f53c4aSTejun Heo * Color space is not full. The current work_color 262073f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 262173f53c4aSTejun Heo * by one. 262273f53c4aSTejun Heo */ 262373f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow)); 262473f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 262573f53c4aSTejun Heo wq->work_color = next_color; 262673f53c4aSTejun Heo 262773f53c4aSTejun Heo if (!wq->first_flusher) { 262873f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 262973f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 263073f53c4aSTejun Heo 263173f53c4aSTejun Heo wq->first_flusher = &this_flusher; 263273f53c4aSTejun Heo 263373f53c4aSTejun Heo if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, 263473f53c4aSTejun Heo wq->work_color)) { 263573f53c4aSTejun Heo /* nothing to flush, done */ 263673f53c4aSTejun Heo wq->flush_color = next_color; 263773f53c4aSTejun Heo wq->first_flusher = NULL; 263873f53c4aSTejun Heo goto out_unlock; 263973f53c4aSTejun Heo } 264073f53c4aSTejun Heo } else { 264173f53c4aSTejun Heo /* wait in queue */ 264273f53c4aSTejun Heo BUG_ON(wq->flush_color == this_flusher.flush_color); 264373f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 264473f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 264573f53c4aSTejun Heo } 264673f53c4aSTejun Heo } else { 264773f53c4aSTejun Heo /* 264873f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 264973f53c4aSTejun Heo * The next flush completion will assign us 265073f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 265173f53c4aSTejun Heo */ 265273f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 265373f53c4aSTejun Heo } 265473f53c4aSTejun Heo 265573f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 265673f53c4aSTejun Heo 265773f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 265873f53c4aSTejun Heo 265973f53c4aSTejun Heo /* 266073f53c4aSTejun Heo * Wake-up-and-cascade phase 266173f53c4aSTejun Heo * 266273f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 266373f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 266473f53c4aSTejun Heo */ 266573f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 266673f53c4aSTejun Heo return; 266773f53c4aSTejun Heo 266873f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 266973f53c4aSTejun Heo 26704ce48b37STejun Heo /* we might have raced, check again with mutex held */ 26714ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 26724ce48b37STejun Heo goto out_unlock; 26734ce48b37STejun Heo 267473f53c4aSTejun Heo wq->first_flusher = NULL; 267573f53c4aSTejun Heo 267673f53c4aSTejun Heo BUG_ON(!list_empty(&this_flusher.list)); 267773f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 267873f53c4aSTejun Heo 267973f53c4aSTejun Heo while (true) { 268073f53c4aSTejun Heo struct wq_flusher *next, *tmp; 268173f53c4aSTejun Heo 268273f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 268373f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 268473f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 268573f53c4aSTejun Heo break; 268673f53c4aSTejun Heo list_del_init(&next->list); 268773f53c4aSTejun Heo complete(&next->done); 268873f53c4aSTejun Heo } 268973f53c4aSTejun Heo 269073f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow) && 269173f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 269273f53c4aSTejun Heo 269373f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 269473f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 269573f53c4aSTejun Heo 269673f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 269773f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 269873f53c4aSTejun Heo /* 269973f53c4aSTejun Heo * Assign the same color to all overflowed 270073f53c4aSTejun Heo * flushers, advance work_color and append to 270173f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 270273f53c4aSTejun Heo * phase for these overflowed flushers. 270373f53c4aSTejun Heo */ 270473f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 270573f53c4aSTejun Heo tmp->flush_color = wq->work_color; 270673f53c4aSTejun Heo 270773f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 270873f53c4aSTejun Heo 270973f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 271073f53c4aSTejun Heo &wq->flusher_queue); 271173f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 271273f53c4aSTejun Heo } 271373f53c4aSTejun Heo 271473f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 271573f53c4aSTejun Heo BUG_ON(wq->flush_color != wq->work_color); 271673f53c4aSTejun Heo break; 271773f53c4aSTejun Heo } 271873f53c4aSTejun Heo 271973f53c4aSTejun Heo /* 272073f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 272173f53c4aSTejun Heo * the new first flusher and arm cwqs. 272273f53c4aSTejun Heo */ 272373f53c4aSTejun Heo BUG_ON(wq->flush_color == wq->work_color); 272473f53c4aSTejun Heo BUG_ON(wq->flush_color != next->flush_color); 272573f53c4aSTejun Heo 272673f53c4aSTejun Heo list_del_init(&next->list); 272773f53c4aSTejun Heo wq->first_flusher = next; 272873f53c4aSTejun Heo 272973f53c4aSTejun Heo if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) 273073f53c4aSTejun Heo break; 273173f53c4aSTejun Heo 273273f53c4aSTejun Heo /* 273373f53c4aSTejun Heo * Meh... this color is already done, clear first 273473f53c4aSTejun Heo * flusher and repeat cascading. 273573f53c4aSTejun Heo */ 273673f53c4aSTejun Heo wq->first_flusher = NULL; 273773f53c4aSTejun Heo } 273873f53c4aSTejun Heo 273973f53c4aSTejun Heo out_unlock: 274073f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 27411da177e4SLinus Torvalds } 2742ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 27431da177e4SLinus Torvalds 27449c5a2ba7STejun Heo /** 27459c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 27469c5a2ba7STejun Heo * @wq: workqueue to drain 27479c5a2ba7STejun Heo * 27489c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 27499c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 27509c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 27519c5a2ba7STejun Heo * repeatedly until it becomes empty. The number of flushing is detemined 27529c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 27539c5a2ba7STejun Heo * takes too long. 27549c5a2ba7STejun Heo */ 27559c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 27569c5a2ba7STejun Heo { 27579c5a2ba7STejun Heo unsigned int flush_cnt = 0; 27589c5a2ba7STejun Heo unsigned int cpu; 27599c5a2ba7STejun Heo 27609c5a2ba7STejun Heo /* 27619c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 27629c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 27639c5a2ba7STejun Heo * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. 27649c5a2ba7STejun Heo */ 27659c5a2ba7STejun Heo spin_lock(&workqueue_lock); 27669c5a2ba7STejun Heo if (!wq->nr_drainers++) 27679c5a2ba7STejun Heo wq->flags |= WQ_DRAINING; 27689c5a2ba7STejun Heo spin_unlock(&workqueue_lock); 27699c5a2ba7STejun Heo reflush: 27709c5a2ba7STejun Heo flush_workqueue(wq); 27719c5a2ba7STejun Heo 27729c5a2ba7STejun Heo for_each_cwq_cpu(cpu, wq) { 27739c5a2ba7STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2774fa2563e4SThomas Tuttle bool drained; 27759c5a2ba7STejun Heo 2776bd7bdd43STejun Heo spin_lock_irq(&cwq->pool->gcwq->lock); 2777fa2563e4SThomas Tuttle drained = !cwq->nr_active && list_empty(&cwq->delayed_works); 2778bd7bdd43STejun Heo spin_unlock_irq(&cwq->pool->gcwq->lock); 2779fa2563e4SThomas Tuttle 2780fa2563e4SThomas Tuttle if (drained) 27819c5a2ba7STejun Heo continue; 27829c5a2ba7STejun Heo 27839c5a2ba7STejun Heo if (++flush_cnt == 10 || 27849c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 2785044c782cSValentin Ilie pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n", 27869c5a2ba7STejun Heo wq->name, flush_cnt); 27879c5a2ba7STejun Heo goto reflush; 27889c5a2ba7STejun Heo } 27899c5a2ba7STejun Heo 27909c5a2ba7STejun Heo spin_lock(&workqueue_lock); 27919c5a2ba7STejun Heo if (!--wq->nr_drainers) 27929c5a2ba7STejun Heo wq->flags &= ~WQ_DRAINING; 27939c5a2ba7STejun Heo spin_unlock(&workqueue_lock); 27949c5a2ba7STejun Heo } 27959c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 27969c5a2ba7STejun Heo 2797606a5020STejun Heo static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) 2798baf59022STejun Heo { 2799baf59022STejun Heo struct worker *worker = NULL; 2800baf59022STejun Heo struct global_cwq *gcwq; 2801baf59022STejun Heo struct cpu_workqueue_struct *cwq; 2802baf59022STejun Heo 2803baf59022STejun Heo might_sleep(); 2804baf59022STejun Heo gcwq = get_work_gcwq(work); 2805baf59022STejun Heo if (!gcwq) 2806baf59022STejun Heo return false; 2807baf59022STejun Heo 2808baf59022STejun Heo spin_lock_irq(&gcwq->lock); 2809baf59022STejun Heo if (!list_empty(&work->entry)) { 2810baf59022STejun Heo /* 2811baf59022STejun Heo * See the comment near try_to_grab_pending()->smp_rmb(). 2812baf59022STejun Heo * If it was re-queued to a different gcwq under us, we 2813baf59022STejun Heo * are not going to wait. 2814baf59022STejun Heo */ 2815baf59022STejun Heo smp_rmb(); 2816baf59022STejun Heo cwq = get_work_cwq(work); 2817bd7bdd43STejun Heo if (unlikely(!cwq || gcwq != cwq->pool->gcwq)) 2818baf59022STejun Heo goto already_gone; 2819606a5020STejun Heo } else { 2820baf59022STejun Heo worker = find_worker_executing_work(gcwq, work); 2821baf59022STejun Heo if (!worker) 2822baf59022STejun Heo goto already_gone; 2823baf59022STejun Heo cwq = worker->current_cwq; 2824606a5020STejun Heo } 2825baf59022STejun Heo 2826baf59022STejun Heo insert_wq_barrier(cwq, barr, work, worker); 2827baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2828baf59022STejun Heo 2829e159489bSTejun Heo /* 2830e159489bSTejun Heo * If @max_active is 1 or rescuer is in use, flushing another work 2831e159489bSTejun Heo * item on the same workqueue may lead to deadlock. Make sure the 2832e159489bSTejun Heo * flusher is not running on the same workqueue by verifying write 2833e159489bSTejun Heo * access. 2834e159489bSTejun Heo */ 2835e159489bSTejun Heo if (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER) 2836baf59022STejun Heo lock_map_acquire(&cwq->wq->lockdep_map); 2837e159489bSTejun Heo else 2838e159489bSTejun Heo lock_map_acquire_read(&cwq->wq->lockdep_map); 2839baf59022STejun Heo lock_map_release(&cwq->wq->lockdep_map); 2840e159489bSTejun Heo 2841baf59022STejun Heo return true; 2842baf59022STejun Heo already_gone: 2843baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2844baf59022STejun Heo return false; 2845baf59022STejun Heo } 2846baf59022STejun Heo 2847db700897SOleg Nesterov /** 2848401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 2849401a8d04STejun Heo * @work: the work to flush 2850db700897SOleg Nesterov * 2851606a5020STejun Heo * Wait until @work has finished execution. @work is guaranteed to be idle 2852606a5020STejun Heo * on return if it hasn't been requeued since flush started. 2853401a8d04STejun Heo * 2854401a8d04STejun Heo * RETURNS: 2855401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2856401a8d04STejun Heo * %false if it was already idle. 2857db700897SOleg Nesterov */ 2858401a8d04STejun Heo bool flush_work(struct work_struct *work) 2859db700897SOleg Nesterov { 2860db700897SOleg Nesterov struct wq_barrier barr; 2861db700897SOleg Nesterov 28620976dfc1SStephen Boyd lock_map_acquire(&work->lockdep_map); 28630976dfc1SStephen Boyd lock_map_release(&work->lockdep_map); 28640976dfc1SStephen Boyd 2865606a5020STejun Heo if (start_flush_work(work, &barr)) { 2866db700897SOleg Nesterov wait_for_completion(&barr.done); 2867dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2868401a8d04STejun Heo return true; 2869606a5020STejun Heo } else { 2870401a8d04STejun Heo return false; 2871db700897SOleg Nesterov } 2872606a5020STejun Heo } 2873db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2874db700897SOleg Nesterov 287536e227d2STejun Heo static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 2876401a8d04STejun Heo { 2877bbb68dfaSTejun Heo unsigned long flags; 28781f1f642eSOleg Nesterov int ret; 28791f1f642eSOleg Nesterov 28801f1f642eSOleg Nesterov do { 2881bbb68dfaSTejun Heo ret = try_to_grab_pending(work, is_dwork, &flags); 2882bbb68dfaSTejun Heo /* 2883bbb68dfaSTejun Heo * If someone else is canceling, wait for the same event it 2884bbb68dfaSTejun Heo * would be waiting for before retrying. 2885bbb68dfaSTejun Heo */ 2886bbb68dfaSTejun Heo if (unlikely(ret == -ENOENT)) 2887606a5020STejun Heo flush_work(work); 28881f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 28891f1f642eSOleg Nesterov 2890bbb68dfaSTejun Heo /* tell other tasks trying to grab @work to back off */ 2891bbb68dfaSTejun Heo mark_work_canceling(work); 2892bbb68dfaSTejun Heo local_irq_restore(flags); 2893bbb68dfaSTejun Heo 2894606a5020STejun Heo flush_work(work); 28957a22ad75STejun Heo clear_work_data(work); 28961f1f642eSOleg Nesterov return ret; 28971f1f642eSOleg Nesterov } 28981f1f642eSOleg Nesterov 28996e84d644SOleg Nesterov /** 2900401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 2901401a8d04STejun Heo * @work: the work to cancel 29026e84d644SOleg Nesterov * 2903401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 2904401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 2905401a8d04STejun Heo * another workqueue. On return from this function, @work is 2906401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 29071f1f642eSOleg Nesterov * 2908401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 2909401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 29106e84d644SOleg Nesterov * 2911401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 29126e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 2913401a8d04STejun Heo * 2914401a8d04STejun Heo * RETURNS: 2915401a8d04STejun Heo * %true if @work was pending, %false otherwise. 29166e84d644SOleg Nesterov */ 2917401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 29186e84d644SOleg Nesterov { 291936e227d2STejun Heo return __cancel_work_timer(work, false); 2920b89deed3SOleg Nesterov } 292128e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2922b89deed3SOleg Nesterov 29236e84d644SOleg Nesterov /** 2924401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 2925401a8d04STejun Heo * @dwork: the delayed work to flush 29266e84d644SOleg Nesterov * 2927401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 2928401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 2929401a8d04STejun Heo * considers the last queueing instance of @dwork. 29301f1f642eSOleg Nesterov * 2931401a8d04STejun Heo * RETURNS: 2932401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2933401a8d04STejun Heo * %false if it was already idle. 29346e84d644SOleg Nesterov */ 2935401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 2936401a8d04STejun Heo { 29378930cabaSTejun Heo local_irq_disable(); 2938401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 29391265057fSTejun Heo __queue_work(dwork->cpu, 2940401a8d04STejun Heo get_work_cwq(&dwork->work)->wq, &dwork->work); 29418930cabaSTejun Heo local_irq_enable(); 2942401a8d04STejun Heo return flush_work(&dwork->work); 2943401a8d04STejun Heo } 2944401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 2945401a8d04STejun Heo 2946401a8d04STejun Heo /** 294757b30ae7STejun Heo * cancel_delayed_work - cancel a delayed work 294857b30ae7STejun Heo * @dwork: delayed_work to cancel 294909383498STejun Heo * 295057b30ae7STejun Heo * Kill off a pending delayed_work. Returns %true if @dwork was pending 295157b30ae7STejun Heo * and canceled; %false if wasn't pending. Note that the work callback 295257b30ae7STejun Heo * function may still be running on return, unless it returns %true and the 295357b30ae7STejun Heo * work doesn't re-arm itself. Explicitly flush or use 295457b30ae7STejun Heo * cancel_delayed_work_sync() to wait on it. 295509383498STejun Heo * 295657b30ae7STejun Heo * This function is safe to call from any context including IRQ handler. 295709383498STejun Heo */ 295857b30ae7STejun Heo bool cancel_delayed_work(struct delayed_work *dwork) 295909383498STejun Heo { 296057b30ae7STejun Heo unsigned long flags; 296157b30ae7STejun Heo int ret; 296257b30ae7STejun Heo 296357b30ae7STejun Heo do { 296457b30ae7STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 296557b30ae7STejun Heo } while (unlikely(ret == -EAGAIN)); 296657b30ae7STejun Heo 296757b30ae7STejun Heo if (unlikely(ret < 0)) 296857b30ae7STejun Heo return false; 296957b30ae7STejun Heo 297057b30ae7STejun Heo set_work_cpu_and_clear_pending(&dwork->work, work_cpu(&dwork->work)); 297157b30ae7STejun Heo local_irq_restore(flags); 2972c0158ca6SDan Magenheimer return ret; 297309383498STejun Heo } 297457b30ae7STejun Heo EXPORT_SYMBOL(cancel_delayed_work); 297509383498STejun Heo 297609383498STejun Heo /** 2977401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 2978401a8d04STejun Heo * @dwork: the delayed work cancel 2979401a8d04STejun Heo * 2980401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 2981401a8d04STejun Heo * 2982401a8d04STejun Heo * RETURNS: 2983401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 2984401a8d04STejun Heo */ 2985401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 29866e84d644SOleg Nesterov { 298736e227d2STejun Heo return __cancel_work_timer(&dwork->work, true); 29886e84d644SOleg Nesterov } 2989f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 29901da177e4SLinus Torvalds 29910fcb78c2SRolf Eike Beer /** 2992c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2993c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2994c1a220e7SZhang Rui * @work: job to be done 2995c1a220e7SZhang Rui * 2996c1a220e7SZhang Rui * This puts a job on a specific cpu 2997c1a220e7SZhang Rui */ 2998d4283e93STejun Heo bool schedule_work_on(int cpu, struct work_struct *work) 2999c1a220e7SZhang Rui { 3000d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 3001c1a220e7SZhang Rui } 3002c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 3003c1a220e7SZhang Rui 30040fcb78c2SRolf Eike Beer /** 3005ae90dd5dSDave Jones * schedule_work - put work task in global workqueue 30061da177e4SLinus Torvalds * @work: job to be done 30071da177e4SLinus Torvalds * 3008d4283e93STejun Heo * Returns %false if @work was already on the kernel-global workqueue and 3009d4283e93STejun Heo * %true otherwise. 301052bad64dSDavid Howells * 30110fcb78c2SRolf Eike Beer * This puts a job in the kernel-global workqueue if it was not already 30120fcb78c2SRolf Eike Beer * queued and leaves it in the same position on the kernel-global 30130fcb78c2SRolf Eike Beer * workqueue otherwise. 30141da177e4SLinus Torvalds */ 3015d4283e93STejun Heo bool schedule_work(struct work_struct *work) 30161da177e4SLinus Torvalds { 30170fcb78c2SRolf Eike Beer return queue_work(system_wq, work); 30181da177e4SLinus Torvalds } 30190fcb78c2SRolf Eike Beer EXPORT_SYMBOL(schedule_work); 30201da177e4SLinus Torvalds 30210fcb78c2SRolf Eike Beer /** 30220fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 30230fcb78c2SRolf Eike Beer * @cpu: cpu to use 30240fcb78c2SRolf Eike Beer * @dwork: job to be done 30250fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 30260fcb78c2SRolf Eike Beer * 30270fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 30280fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 30290fcb78c2SRolf Eike Beer */ 3030d4283e93STejun Heo bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork, 3031d4283e93STejun Heo unsigned long delay) 30321da177e4SLinus Torvalds { 3033d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 30341da177e4SLinus Torvalds } 3035ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 30361da177e4SLinus Torvalds 3037b6136773SAndrew Morton /** 30380a13c00eSTejun Heo * schedule_delayed_work - put work task in global workqueue after delay 30390a13c00eSTejun Heo * @dwork: job to be done 30400a13c00eSTejun Heo * @delay: number of jiffies to wait or 0 for immediate execution 30410a13c00eSTejun Heo * 30420a13c00eSTejun Heo * After waiting for a given time this puts a job in the kernel-global 30430a13c00eSTejun Heo * workqueue. 30440a13c00eSTejun Heo */ 3045d4283e93STejun Heo bool schedule_delayed_work(struct delayed_work *dwork, unsigned long delay) 30460a13c00eSTejun Heo { 30470a13c00eSTejun Heo return queue_delayed_work(system_wq, dwork, delay); 30480a13c00eSTejun Heo } 30490a13c00eSTejun Heo EXPORT_SYMBOL(schedule_delayed_work); 30500a13c00eSTejun Heo 30510a13c00eSTejun Heo /** 305231ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 3053b6136773SAndrew Morton * @func: the function to call 3054b6136773SAndrew Morton * 305531ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 305631ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 3057b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 305831ddd871STejun Heo * 305931ddd871STejun Heo * RETURNS: 306031ddd871STejun Heo * 0 on success, -errno on failure. 3061b6136773SAndrew Morton */ 306265f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 306315316ba8SChristoph Lameter { 306415316ba8SChristoph Lameter int cpu; 306538f51568SNamhyung Kim struct work_struct __percpu *works; 306615316ba8SChristoph Lameter 3067b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 3068b6136773SAndrew Morton if (!works) 306915316ba8SChristoph Lameter return -ENOMEM; 3070b6136773SAndrew Morton 307195402b38SGautham R Shenoy get_online_cpus(); 307293981800STejun Heo 307315316ba8SChristoph Lameter for_each_online_cpu(cpu) { 30749bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 30759bfb1839SIngo Molnar 30769bfb1839SIngo Molnar INIT_WORK(work, func); 30778de6d308SOleg Nesterov schedule_work_on(cpu, work); 307815316ba8SChristoph Lameter } 307993981800STejun Heo 308093981800STejun Heo for_each_online_cpu(cpu) 30818616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 308293981800STejun Heo 308395402b38SGautham R Shenoy put_online_cpus(); 3084b6136773SAndrew Morton free_percpu(works); 308515316ba8SChristoph Lameter return 0; 308615316ba8SChristoph Lameter } 308715316ba8SChristoph Lameter 3088eef6a7d5SAlan Stern /** 3089eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 3090eef6a7d5SAlan Stern * 3091eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 3092eef6a7d5SAlan Stern * completion. 3093eef6a7d5SAlan Stern * 3094eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 3095eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 3096eef6a7d5SAlan Stern * will lead to deadlock: 3097eef6a7d5SAlan Stern * 3098eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 3099eef6a7d5SAlan Stern * a lock held by your code or its caller. 3100eef6a7d5SAlan Stern * 3101eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 3102eef6a7d5SAlan Stern * 3103eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 3104eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 3105eef6a7d5SAlan Stern * what locks they need, which you have no control over. 3106eef6a7d5SAlan Stern * 3107eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 3108eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 3109eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 3110eef6a7d5SAlan Stern * cancel_work_sync() instead. 3111eef6a7d5SAlan Stern */ 31121da177e4SLinus Torvalds void flush_scheduled_work(void) 31131da177e4SLinus Torvalds { 3114d320c038STejun Heo flush_workqueue(system_wq); 31151da177e4SLinus Torvalds } 3116ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 31171da177e4SLinus Torvalds 31181da177e4SLinus Torvalds /** 31191fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 31201fa44ecaSJames Bottomley * @fn: the function to execute 31211fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 31221fa44ecaSJames Bottomley * be available when the work executes) 31231fa44ecaSJames Bottomley * 31241fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 31251fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 31261fa44ecaSJames Bottomley * 31271fa44ecaSJames Bottomley * Returns: 0 - function was executed 31281fa44ecaSJames Bottomley * 1 - function was scheduled for execution 31291fa44ecaSJames Bottomley */ 313065f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 31311fa44ecaSJames Bottomley { 31321fa44ecaSJames Bottomley if (!in_interrupt()) { 313365f27f38SDavid Howells fn(&ew->work); 31341fa44ecaSJames Bottomley return 0; 31351fa44ecaSJames Bottomley } 31361fa44ecaSJames Bottomley 313765f27f38SDavid Howells INIT_WORK(&ew->work, fn); 31381fa44ecaSJames Bottomley schedule_work(&ew->work); 31391fa44ecaSJames Bottomley 31401fa44ecaSJames Bottomley return 1; 31411fa44ecaSJames Bottomley } 31421fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 31431fa44ecaSJames Bottomley 31441da177e4SLinus Torvalds int keventd_up(void) 31451da177e4SLinus Torvalds { 3146d320c038STejun Heo return system_wq != NULL; 31471da177e4SLinus Torvalds } 31481da177e4SLinus Torvalds 3149bdbc5dd7STejun Heo static int alloc_cwqs(struct workqueue_struct *wq) 31501da177e4SLinus Torvalds { 31513af24433SOleg Nesterov /* 31520f900049STejun Heo * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. 31530f900049STejun Heo * Make sure that the alignment isn't lower than that of 31540f900049STejun Heo * unsigned long long. 31553af24433SOleg Nesterov */ 31560f900049STejun Heo const size_t size = sizeof(struct cpu_workqueue_struct); 31570f900049STejun Heo const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, 31580f900049STejun Heo __alignof__(unsigned long long)); 31593af24433SOleg Nesterov 3160e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 3161f3421797STejun Heo wq->cpu_wq.pcpu = __alloc_percpu(size, align); 3162931ac77eSTejun Heo else { 31630f900049STejun Heo void *ptr; 3164e1d8aa9fSFrederic Weisbecker 31650f900049STejun Heo /* 3166f3421797STejun Heo * Allocate enough room to align cwq and put an extra 3167f3421797STejun Heo * pointer at the end pointing back to the originally 3168f3421797STejun Heo * allocated pointer which will be used for free. 31690f900049STejun Heo */ 3170bdbc5dd7STejun Heo ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); 3171bdbc5dd7STejun Heo if (ptr) { 3172bdbc5dd7STejun Heo wq->cpu_wq.single = PTR_ALIGN(ptr, align); 3173bdbc5dd7STejun Heo *(void **)(wq->cpu_wq.single + 1) = ptr; 3174bdbc5dd7STejun Heo } 31753af24433SOleg Nesterov } 31763af24433SOleg Nesterov 31770415b00dSTejun Heo /* just in case, make sure it's actually aligned */ 3178bdbc5dd7STejun Heo BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); 3179bdbc5dd7STejun Heo return wq->cpu_wq.v ? 0 : -ENOMEM; 31800f900049STejun Heo } 31810f900049STejun Heo 3182bdbc5dd7STejun Heo static void free_cwqs(struct workqueue_struct *wq) 318306ba38a9SOleg Nesterov { 3184e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 3185bdbc5dd7STejun Heo free_percpu(wq->cpu_wq.pcpu); 3186f3421797STejun Heo else if (wq->cpu_wq.single) { 3187f3421797STejun Heo /* the pointer to free is stored right after the cwq */ 3188f3421797STejun Heo kfree(*(void **)(wq->cpu_wq.single + 1)); 318906ba38a9SOleg Nesterov } 319006ba38a9SOleg Nesterov } 319106ba38a9SOleg Nesterov 3192f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 3193f3421797STejun Heo const char *name) 3194b71ab8c2STejun Heo { 3195f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 3196f3421797STejun Heo 3197f3421797STejun Heo if (max_active < 1 || max_active > lim) 3198044c782cSValentin Ilie pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 3199f3421797STejun Heo max_active, name, 1, lim); 3200b71ab8c2STejun Heo 3201f3421797STejun Heo return clamp_val(max_active, 1, lim); 3202b71ab8c2STejun Heo } 3203b71ab8c2STejun Heo 3204b196be89STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *fmt, 320597e37d7bSTejun Heo unsigned int flags, 32061e19ffc6STejun Heo int max_active, 3207eb13ba87SJohannes Berg struct lock_class_key *key, 3208b196be89STejun Heo const char *lock_name, ...) 32093af24433SOleg Nesterov { 3210b196be89STejun Heo va_list args, args1; 32113af24433SOleg Nesterov struct workqueue_struct *wq; 3212c34056a3STejun Heo unsigned int cpu; 3213b196be89STejun Heo size_t namelen; 3214b196be89STejun Heo 3215b196be89STejun Heo /* determine namelen, allocate wq and format name */ 3216b196be89STejun Heo va_start(args, lock_name); 3217b196be89STejun Heo va_copy(args1, args); 3218b196be89STejun Heo namelen = vsnprintf(NULL, 0, fmt, args) + 1; 3219b196be89STejun Heo 3220b196be89STejun Heo wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL); 3221b196be89STejun Heo if (!wq) 3222b196be89STejun Heo goto err; 3223b196be89STejun Heo 3224b196be89STejun Heo vsnprintf(wq->name, namelen, fmt, args1); 3225b196be89STejun Heo va_end(args); 3226b196be89STejun Heo va_end(args1); 32273af24433SOleg Nesterov 3228f3421797STejun Heo /* 32296370a6adSTejun Heo * Workqueues which may be used during memory reclaim should 32306370a6adSTejun Heo * have a rescuer to guarantee forward progress. 32316370a6adSTejun Heo */ 32326370a6adSTejun Heo if (flags & WQ_MEM_RECLAIM) 32336370a6adSTejun Heo flags |= WQ_RESCUER; 32346370a6adSTejun Heo 3235d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 3236b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 32373af24433SOleg Nesterov 3238b196be89STejun Heo /* init wq */ 323997e37d7bSTejun Heo wq->flags = flags; 3240a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 324173f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 324273f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 0); 324373f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 324473f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 32453af24433SOleg Nesterov 3246eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 3247cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 32483af24433SOleg Nesterov 3249bdbc5dd7STejun Heo if (alloc_cwqs(wq) < 0) 3250bdbc5dd7STejun Heo goto err; 3251bdbc5dd7STejun Heo 3252f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 32531537663fSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 32548b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 32553270476aSTejun Heo int pool_idx = (bool)(flags & WQ_HIGHPRI); 32561537663fSTejun Heo 32570f900049STejun Heo BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 32583270476aSTejun Heo cwq->pool = &gcwq->pools[pool_idx]; 3259c34056a3STejun Heo cwq->wq = wq; 326073f53c4aSTejun Heo cwq->flush_color = -1; 32611e19ffc6STejun Heo cwq->max_active = max_active; 32621e19ffc6STejun Heo INIT_LIST_HEAD(&cwq->delayed_works); 3263e22bee78STejun Heo } 32641537663fSTejun Heo 3265e22bee78STejun Heo if (flags & WQ_RESCUER) { 3266e22bee78STejun Heo struct worker *rescuer; 3267e22bee78STejun Heo 3268f2e005aaSTejun Heo if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) 3269e22bee78STejun Heo goto err; 3270e22bee78STejun Heo 3271e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 3272e22bee78STejun Heo if (!rescuer) 3273e22bee78STejun Heo goto err; 3274e22bee78STejun Heo 3275111c225aSTejun Heo rescuer->rescue_wq = wq; 3276111c225aSTejun Heo rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", 3277b196be89STejun Heo wq->name); 3278e22bee78STejun Heo if (IS_ERR(rescuer->task)) 3279e22bee78STejun Heo goto err; 3280e22bee78STejun Heo 3281e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 3282e22bee78STejun Heo wake_up_process(rescuer->task); 32833af24433SOleg Nesterov } 32841537663fSTejun Heo 32853af24433SOleg Nesterov /* 3286a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 3287a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 3288a0a1a5fdSTejun Heo * workqueue to workqueues list. 32893af24433SOleg Nesterov */ 32903af24433SOleg Nesterov spin_lock(&workqueue_lock); 3291a0a1a5fdSTejun Heo 329258a69cb4STejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZABLE) 3293f3421797STejun Heo for_each_cwq_cpu(cpu, wq) 3294a0a1a5fdSTejun Heo get_cwq(cpu, wq)->max_active = 0; 3295a0a1a5fdSTejun Heo 32963af24433SOleg Nesterov list_add(&wq->list, &workqueues); 3297a0a1a5fdSTejun Heo 32983af24433SOleg Nesterov spin_unlock(&workqueue_lock); 32993af24433SOleg Nesterov 33003af24433SOleg Nesterov return wq; 33014690c4abSTejun Heo err: 33024690c4abSTejun Heo if (wq) { 3303bdbc5dd7STejun Heo free_cwqs(wq); 3304f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 3305e22bee78STejun Heo kfree(wq->rescuer); 33064690c4abSTejun Heo kfree(wq); 33073af24433SOleg Nesterov } 33084690c4abSTejun Heo return NULL; 33091da177e4SLinus Torvalds } 3310d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 33111da177e4SLinus Torvalds 33123af24433SOleg Nesterov /** 33133af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 33143af24433SOleg Nesterov * @wq: target workqueue 33153af24433SOleg Nesterov * 33163af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 33173af24433SOleg Nesterov */ 33183af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 33193af24433SOleg Nesterov { 3320c8e55f36STejun Heo unsigned int cpu; 33213af24433SOleg Nesterov 33229c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 33239c5a2ba7STejun Heo drain_workqueue(wq); 3324c8efcc25STejun Heo 3325a0a1a5fdSTejun Heo /* 3326a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 3327a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 3328a0a1a5fdSTejun Heo */ 332995402b38SGautham R Shenoy spin_lock(&workqueue_lock); 33303af24433SOleg Nesterov list_del(&wq->list); 333195402b38SGautham R Shenoy spin_unlock(&workqueue_lock); 33323af24433SOleg Nesterov 3333e22bee78STejun Heo /* sanity check */ 3334f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 333573f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 333673f53c4aSTejun Heo int i; 33373af24433SOleg Nesterov 333873f53c4aSTejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 333973f53c4aSTejun Heo BUG_ON(cwq->nr_in_flight[i]); 33401e19ffc6STejun Heo BUG_ON(cwq->nr_active); 33411e19ffc6STejun Heo BUG_ON(!list_empty(&cwq->delayed_works)); 334273f53c4aSTejun Heo } 33431537663fSTejun Heo 3344e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 3345e22bee78STejun Heo kthread_stop(wq->rescuer->task); 3346f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 33478d9df9f0SXiaotian Feng kfree(wq->rescuer); 3348e22bee78STejun Heo } 3349e22bee78STejun Heo 3350bdbc5dd7STejun Heo free_cwqs(wq); 33513af24433SOleg Nesterov kfree(wq); 33523af24433SOleg Nesterov } 33533af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 33543af24433SOleg Nesterov 3355dcd989cbSTejun Heo /** 33569f4bd4cdSLai Jiangshan * cwq_set_max_active - adjust max_active of a cwq 33579f4bd4cdSLai Jiangshan * @cwq: target cpu_workqueue_struct 33589f4bd4cdSLai Jiangshan * @max_active: new max_active value. 33599f4bd4cdSLai Jiangshan * 33609f4bd4cdSLai Jiangshan * Set @cwq->max_active to @max_active and activate delayed works if 33619f4bd4cdSLai Jiangshan * increased. 33629f4bd4cdSLai Jiangshan * 33639f4bd4cdSLai Jiangshan * CONTEXT: 33649f4bd4cdSLai Jiangshan * spin_lock_irq(gcwq->lock). 33659f4bd4cdSLai Jiangshan */ 33669f4bd4cdSLai Jiangshan static void cwq_set_max_active(struct cpu_workqueue_struct *cwq, int max_active) 33679f4bd4cdSLai Jiangshan { 33689f4bd4cdSLai Jiangshan cwq->max_active = max_active; 33699f4bd4cdSLai Jiangshan 33709f4bd4cdSLai Jiangshan while (!list_empty(&cwq->delayed_works) && 33719f4bd4cdSLai Jiangshan cwq->nr_active < cwq->max_active) 33729f4bd4cdSLai Jiangshan cwq_activate_first_delayed(cwq); 33739f4bd4cdSLai Jiangshan } 33749f4bd4cdSLai Jiangshan 33759f4bd4cdSLai Jiangshan /** 3376dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 3377dcd989cbSTejun Heo * @wq: target workqueue 3378dcd989cbSTejun Heo * @max_active: new max_active value. 3379dcd989cbSTejun Heo * 3380dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 3381dcd989cbSTejun Heo * 3382dcd989cbSTejun Heo * CONTEXT: 3383dcd989cbSTejun Heo * Don't call from IRQ context. 3384dcd989cbSTejun Heo */ 3385dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 3386dcd989cbSTejun Heo { 3387dcd989cbSTejun Heo unsigned int cpu; 3388dcd989cbSTejun Heo 3389f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 3390dcd989cbSTejun Heo 3391dcd989cbSTejun Heo spin_lock(&workqueue_lock); 3392dcd989cbSTejun Heo 3393dcd989cbSTejun Heo wq->saved_max_active = max_active; 3394dcd989cbSTejun Heo 3395f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 339635b6bb63STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 339735b6bb63STejun Heo struct worker_pool *pool = cwq->pool; 339835b6bb63STejun Heo struct global_cwq *gcwq = pool->gcwq; 3399dcd989cbSTejun Heo 3400dcd989cbSTejun Heo spin_lock_irq(&gcwq->lock); 3401dcd989cbSTejun Heo 340258a69cb4STejun Heo if (!(wq->flags & WQ_FREEZABLE) || 340335b6bb63STejun Heo !(pool->flags & POOL_FREEZING)) 340435b6bb63STejun Heo cwq_set_max_active(cwq, max_active); 3405dcd989cbSTejun Heo 3406dcd989cbSTejun Heo spin_unlock_irq(&gcwq->lock); 3407dcd989cbSTejun Heo } 3408dcd989cbSTejun Heo 3409dcd989cbSTejun Heo spin_unlock(&workqueue_lock); 3410dcd989cbSTejun Heo } 3411dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 3412dcd989cbSTejun Heo 3413dcd989cbSTejun Heo /** 3414dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 3415dcd989cbSTejun Heo * @cpu: CPU in question 3416dcd989cbSTejun Heo * @wq: target workqueue 3417dcd989cbSTejun Heo * 3418dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 3419dcd989cbSTejun Heo * no synchronization around this function and the test result is 3420dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3421dcd989cbSTejun Heo * 3422dcd989cbSTejun Heo * RETURNS: 3423dcd989cbSTejun Heo * %true if congested, %false otherwise. 3424dcd989cbSTejun Heo */ 3425dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 3426dcd989cbSTejun Heo { 3427dcd989cbSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3428dcd989cbSTejun Heo 3429dcd989cbSTejun Heo return !list_empty(&cwq->delayed_works); 3430dcd989cbSTejun Heo } 3431dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 3432dcd989cbSTejun Heo 3433dcd989cbSTejun Heo /** 3434dcd989cbSTejun Heo * work_cpu - return the last known associated cpu for @work 3435dcd989cbSTejun Heo * @work: the work of interest 3436dcd989cbSTejun Heo * 3437dcd989cbSTejun Heo * RETURNS: 3438bdbc5dd7STejun Heo * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. 3439dcd989cbSTejun Heo */ 3440e2905b29STejun Heo static unsigned int work_cpu(struct work_struct *work) 3441dcd989cbSTejun Heo { 3442dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3443dcd989cbSTejun Heo 3444bdbc5dd7STejun Heo return gcwq ? gcwq->cpu : WORK_CPU_NONE; 3445dcd989cbSTejun Heo } 3446dcd989cbSTejun Heo 3447dcd989cbSTejun Heo /** 3448dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 3449dcd989cbSTejun Heo * @work: the work to be tested 3450dcd989cbSTejun Heo * 3451dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 3452dcd989cbSTejun Heo * synchronization around this function and the test result is 3453dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3454dcd989cbSTejun Heo * Especially for reentrant wqs, the pending state might hide the 3455dcd989cbSTejun Heo * running state. 3456dcd989cbSTejun Heo * 3457dcd989cbSTejun Heo * RETURNS: 3458dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 3459dcd989cbSTejun Heo */ 3460dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 3461dcd989cbSTejun Heo { 3462dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3463dcd989cbSTejun Heo unsigned long flags; 3464dcd989cbSTejun Heo unsigned int ret = 0; 3465dcd989cbSTejun Heo 3466dcd989cbSTejun Heo if (!gcwq) 3467999767beSJoonsoo Kim return 0; 3468dcd989cbSTejun Heo 3469dcd989cbSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 3470dcd989cbSTejun Heo 3471dcd989cbSTejun Heo if (work_pending(work)) 3472dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 3473dcd989cbSTejun Heo if (find_worker_executing_work(gcwq, work)) 3474dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 3475dcd989cbSTejun Heo 3476dcd989cbSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 3477dcd989cbSTejun Heo 3478dcd989cbSTejun Heo return ret; 3479dcd989cbSTejun Heo } 3480dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 3481dcd989cbSTejun Heo 3482db7bccf4STejun Heo /* 3483db7bccf4STejun Heo * CPU hotplug. 3484db7bccf4STejun Heo * 3485e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 3486e22bee78STejun Heo * are a lot of assumptions on strong associations among work, cwq and 3487e22bee78STejun Heo * gcwq which make migrating pending and scheduled works very 3488e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 3489e22bee78STejun Heo * gcwqs serve mix of short, long and very long running works making 3490e22bee78STejun Heo * blocked draining impractical. 3491e22bee78STejun Heo * 349224647570STejun Heo * This is solved by allowing the pools to be disassociated from the CPU 3493628c78e7STejun Heo * running as an unbound one and allowing it to be reattached later if the 3494628c78e7STejun Heo * cpu comes back online. 3495db7bccf4STejun Heo */ 3496db7bccf4STejun Heo 349760373152STejun Heo /* claim manager positions of all pools */ 3498b2eb83d1SLai Jiangshan static void gcwq_claim_assoc_and_lock(struct global_cwq *gcwq) 349960373152STejun Heo { 350060373152STejun Heo struct worker_pool *pool; 350160373152STejun Heo 350260373152STejun Heo for_each_worker_pool(pool, gcwq) 3503b2eb83d1SLai Jiangshan mutex_lock_nested(&pool->assoc_mutex, pool - gcwq->pools); 35048db25e78STejun Heo spin_lock_irq(&gcwq->lock); 350560373152STejun Heo } 350660373152STejun Heo 350760373152STejun Heo /* release manager positions */ 3508b2eb83d1SLai Jiangshan static void gcwq_release_assoc_and_unlock(struct global_cwq *gcwq) 350960373152STejun Heo { 351060373152STejun Heo struct worker_pool *pool; 351160373152STejun Heo 35128db25e78STejun Heo spin_unlock_irq(&gcwq->lock); 351360373152STejun Heo for_each_worker_pool(pool, gcwq) 3514b2eb83d1SLai Jiangshan mutex_unlock(&pool->assoc_mutex); 351560373152STejun Heo } 351660373152STejun Heo 3517628c78e7STejun Heo static void gcwq_unbind_fn(struct work_struct *work) 3518db7bccf4STejun Heo { 3519628c78e7STejun Heo struct global_cwq *gcwq = get_gcwq(smp_processor_id()); 35204ce62e9eSTejun Heo struct worker_pool *pool; 3521db7bccf4STejun Heo struct worker *worker; 3522db7bccf4STejun Heo struct hlist_node *pos; 3523db7bccf4STejun Heo int i; 3524db7bccf4STejun Heo 3525db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3526db7bccf4STejun Heo 3527b2eb83d1SLai Jiangshan gcwq_claim_assoc_and_lock(gcwq); 3528e22bee78STejun Heo 3529f2d5a0eeSTejun Heo /* 3530f2d5a0eeSTejun Heo * We've claimed all manager positions. Make all workers unbound 3531f2d5a0eeSTejun Heo * and set DISASSOCIATED. Before this, all workers except for the 3532f2d5a0eeSTejun Heo * ones which are still executing works from before the last CPU 3533f2d5a0eeSTejun Heo * down must be on the cpu. After this, they may become diasporas. 3534f2d5a0eeSTejun Heo */ 353560373152STejun Heo for_each_worker_pool(pool, gcwq) 35364ce62e9eSTejun Heo list_for_each_entry(worker, &pool->idle_list, entry) 3537403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 3538db7bccf4STejun Heo 3539db7bccf4STejun Heo for_each_busy_worker(worker, i, pos, gcwq) 3540403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 3541db7bccf4STejun Heo 354224647570STejun Heo for_each_worker_pool(pool, gcwq) 354324647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 3544f2d5a0eeSTejun Heo 3545b2eb83d1SLai Jiangshan gcwq_release_assoc_and_unlock(gcwq); 3546e22bee78STejun Heo 3547e22bee78STejun Heo /* 3548628c78e7STejun Heo * Call schedule() so that we cross rq->lock and thus can guarantee 3549628c78e7STejun Heo * sched callbacks see the %WORKER_UNBOUND flag. This is necessary 3550628c78e7STejun Heo * as scheduler callbacks may be invoked from other cpus. 3551628c78e7STejun Heo */ 3552628c78e7STejun Heo schedule(); 3553628c78e7STejun Heo 3554628c78e7STejun Heo /* 3555628c78e7STejun Heo * Sched callbacks are disabled now. Zap nr_running. After this, 3556628c78e7STejun Heo * nr_running stays zero and need_more_worker() and keep_working() 3557628c78e7STejun Heo * are always true as long as the worklist is not empty. @gcwq now 3558628c78e7STejun Heo * behaves as unbound (in terms of concurrency management) gcwq 3559628c78e7STejun Heo * which is served by workers tied to the CPU. 3560628c78e7STejun Heo * 3561628c78e7STejun Heo * On return from this function, the current worker would trigger 3562628c78e7STejun Heo * unbound chain execution of pending work items if other workers 3563628c78e7STejun Heo * didn't already. 3564e22bee78STejun Heo */ 35654ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) 35664ce62e9eSTejun Heo atomic_set(get_pool_nr_running(pool), 0); 3567db7bccf4STejun Heo } 3568db7bccf4STejun Heo 35698db25e78STejun Heo /* 35708db25e78STejun Heo * Workqueues should be brought up before normal priority CPU notifiers. 35718db25e78STejun Heo * This will be registered high priority CPU notifier. 35728db25e78STejun Heo */ 35739fdf9b73SLai Jiangshan static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb, 35741da177e4SLinus Torvalds unsigned long action, 35751da177e4SLinus Torvalds void *hcpu) 35761da177e4SLinus Torvalds { 35773af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 3578db7bccf4STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 35794ce62e9eSTejun Heo struct worker_pool *pool; 35801da177e4SLinus Torvalds 35818db25e78STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 35823af24433SOleg Nesterov case CPU_UP_PREPARE: 35834ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) { 35843ce63377STejun Heo struct worker *worker; 35853ce63377STejun Heo 35863ce63377STejun Heo if (pool->nr_workers) 35873ce63377STejun Heo continue; 35883ce63377STejun Heo 35893ce63377STejun Heo worker = create_worker(pool); 35903ce63377STejun Heo if (!worker) 35913ce63377STejun Heo return NOTIFY_BAD; 35923ce63377STejun Heo 35933ce63377STejun Heo spin_lock_irq(&gcwq->lock); 35943ce63377STejun Heo start_worker(worker); 35953ce63377STejun Heo spin_unlock_irq(&gcwq->lock); 35963af24433SOleg Nesterov } 35971da177e4SLinus Torvalds break; 35981da177e4SLinus Torvalds 359965758202STejun Heo case CPU_DOWN_FAILED: 360065758202STejun Heo case CPU_ONLINE: 3601b2eb83d1SLai Jiangshan gcwq_claim_assoc_and_lock(gcwq); 360224647570STejun Heo for_each_worker_pool(pool, gcwq) 360324647570STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 36048db25e78STejun Heo rebind_workers(gcwq); 3605b2eb83d1SLai Jiangshan gcwq_release_assoc_and_unlock(gcwq); 36068db25e78STejun Heo break; 360765758202STejun Heo } 360865758202STejun Heo return NOTIFY_OK; 360965758202STejun Heo } 361065758202STejun Heo 361165758202STejun Heo /* 361265758202STejun Heo * Workqueues should be brought down after normal priority CPU notifiers. 361365758202STejun Heo * This will be registered as low priority CPU notifier. 361465758202STejun Heo */ 36159fdf9b73SLai Jiangshan static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb, 361665758202STejun Heo unsigned long action, 361765758202STejun Heo void *hcpu) 361865758202STejun Heo { 36198db25e78STejun Heo unsigned int cpu = (unsigned long)hcpu; 36208db25e78STejun Heo struct work_struct unbind_work; 36218db25e78STejun Heo 362265758202STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 362365758202STejun Heo case CPU_DOWN_PREPARE: 36248db25e78STejun Heo /* unbinding should happen on the local CPU */ 36258db25e78STejun Heo INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn); 36267635d2fdSJoonsoo Kim queue_work_on(cpu, system_highpri_wq, &unbind_work); 36278db25e78STejun Heo flush_work(&unbind_work); 36288db25e78STejun Heo break; 362965758202STejun Heo } 363065758202STejun Heo return NOTIFY_OK; 363165758202STejun Heo } 363265758202STejun Heo 36332d3854a3SRusty Russell #ifdef CONFIG_SMP 36348ccad40dSRusty Russell 36352d3854a3SRusty Russell struct work_for_cpu { 3636ed48ece2STejun Heo struct work_struct work; 36372d3854a3SRusty Russell long (*fn)(void *); 36382d3854a3SRusty Russell void *arg; 36392d3854a3SRusty Russell long ret; 36402d3854a3SRusty Russell }; 36412d3854a3SRusty Russell 3642ed48ece2STejun Heo static void work_for_cpu_fn(struct work_struct *work) 36432d3854a3SRusty Russell { 3644ed48ece2STejun Heo struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); 3645ed48ece2STejun Heo 36462d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 36472d3854a3SRusty Russell } 36482d3854a3SRusty Russell 36492d3854a3SRusty Russell /** 36502d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 36512d3854a3SRusty Russell * @cpu: the cpu to run on 36522d3854a3SRusty Russell * @fn: the function to run 36532d3854a3SRusty Russell * @arg: the function arg 36542d3854a3SRusty Russell * 365531ad9081SRusty Russell * This will return the value @fn returns. 365631ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 36576b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 36582d3854a3SRusty Russell */ 36592d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 36602d3854a3SRusty Russell { 3661ed48ece2STejun Heo struct work_for_cpu wfc = { .fn = fn, .arg = arg }; 36622d3854a3SRusty Russell 3663ed48ece2STejun Heo INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); 3664ed48ece2STejun Heo schedule_work_on(cpu, &wfc.work); 3665ed48ece2STejun Heo flush_work(&wfc.work); 36662d3854a3SRusty Russell return wfc.ret; 36672d3854a3SRusty Russell } 36682d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 36692d3854a3SRusty Russell #endif /* CONFIG_SMP */ 36702d3854a3SRusty Russell 3671a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3672e7577c50SRusty Russell 3673a0a1a5fdSTejun Heo /** 3674a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3675a0a1a5fdSTejun Heo * 367658a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 367758a69cb4STejun Heo * workqueues will queue new works to their frozen_works list instead of 367858a69cb4STejun Heo * gcwq->worklist. 3679a0a1a5fdSTejun Heo * 3680a0a1a5fdSTejun Heo * CONTEXT: 36818b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3682a0a1a5fdSTejun Heo */ 3683a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3684a0a1a5fdSTejun Heo { 3685a0a1a5fdSTejun Heo unsigned int cpu; 3686a0a1a5fdSTejun Heo 3687a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3688a0a1a5fdSTejun Heo 3689a0a1a5fdSTejun Heo BUG_ON(workqueue_freezing); 3690a0a1a5fdSTejun Heo workqueue_freezing = true; 3691a0a1a5fdSTejun Heo 3692f3421797STejun Heo for_each_gcwq_cpu(cpu) { 36938b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 369435b6bb63STejun Heo struct worker_pool *pool; 3695bdbc5dd7STejun Heo struct workqueue_struct *wq; 36968b03ae3cSTejun Heo 36978b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 36988b03ae3cSTejun Heo 369935b6bb63STejun Heo for_each_worker_pool(pool, gcwq) { 370035b6bb63STejun Heo WARN_ON_ONCE(pool->flags & POOL_FREEZING); 370135b6bb63STejun Heo pool->flags |= POOL_FREEZING; 370235b6bb63STejun Heo } 3703db7bccf4STejun Heo 3704a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3705a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3706a0a1a5fdSTejun Heo 370758a69cb4STejun Heo if (cwq && wq->flags & WQ_FREEZABLE) 3708a0a1a5fdSTejun Heo cwq->max_active = 0; 37091da177e4SLinus Torvalds } 37108b03ae3cSTejun Heo 37118b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3712a0a1a5fdSTejun Heo } 3713a0a1a5fdSTejun Heo 3714a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3715a0a1a5fdSTejun Heo } 3716a0a1a5fdSTejun Heo 3717a0a1a5fdSTejun Heo /** 371858a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 3719a0a1a5fdSTejun Heo * 3720a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3721a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3722a0a1a5fdSTejun Heo * 3723a0a1a5fdSTejun Heo * CONTEXT: 3724a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3725a0a1a5fdSTejun Heo * 3726a0a1a5fdSTejun Heo * RETURNS: 372758a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 372858a69cb4STejun Heo * is complete. 3729a0a1a5fdSTejun Heo */ 3730a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3731a0a1a5fdSTejun Heo { 3732a0a1a5fdSTejun Heo unsigned int cpu; 3733a0a1a5fdSTejun Heo bool busy = false; 3734a0a1a5fdSTejun Heo 3735a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3736a0a1a5fdSTejun Heo 3737a0a1a5fdSTejun Heo BUG_ON(!workqueue_freezing); 3738a0a1a5fdSTejun Heo 3739f3421797STejun Heo for_each_gcwq_cpu(cpu) { 3740bdbc5dd7STejun Heo struct workqueue_struct *wq; 3741a0a1a5fdSTejun Heo /* 3742a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3743a0a1a5fdSTejun Heo * to peek without lock. 3744a0a1a5fdSTejun Heo */ 3745a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3746a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3747a0a1a5fdSTejun Heo 374858a69cb4STejun Heo if (!cwq || !(wq->flags & WQ_FREEZABLE)) 3749a0a1a5fdSTejun Heo continue; 3750a0a1a5fdSTejun Heo 3751a0a1a5fdSTejun Heo BUG_ON(cwq->nr_active < 0); 3752a0a1a5fdSTejun Heo if (cwq->nr_active) { 3753a0a1a5fdSTejun Heo busy = true; 3754a0a1a5fdSTejun Heo goto out_unlock; 3755a0a1a5fdSTejun Heo } 3756a0a1a5fdSTejun Heo } 3757a0a1a5fdSTejun Heo } 3758a0a1a5fdSTejun Heo out_unlock: 3759a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3760a0a1a5fdSTejun Heo return busy; 3761a0a1a5fdSTejun Heo } 3762a0a1a5fdSTejun Heo 3763a0a1a5fdSTejun Heo /** 3764a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3765a0a1a5fdSTejun Heo * 3766a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 37677e11629dSTejun Heo * frozen works are transferred to their respective gcwq worklists. 3768a0a1a5fdSTejun Heo * 3769a0a1a5fdSTejun Heo * CONTEXT: 37708b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3771a0a1a5fdSTejun Heo */ 3772a0a1a5fdSTejun Heo void thaw_workqueues(void) 3773a0a1a5fdSTejun Heo { 3774a0a1a5fdSTejun Heo unsigned int cpu; 3775a0a1a5fdSTejun Heo 3776a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3777a0a1a5fdSTejun Heo 3778a0a1a5fdSTejun Heo if (!workqueue_freezing) 3779a0a1a5fdSTejun Heo goto out_unlock; 3780a0a1a5fdSTejun Heo 3781f3421797STejun Heo for_each_gcwq_cpu(cpu) { 37828b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 37834ce62e9eSTejun Heo struct worker_pool *pool; 3784bdbc5dd7STejun Heo struct workqueue_struct *wq; 37858b03ae3cSTejun Heo 37868b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 37878b03ae3cSTejun Heo 378835b6bb63STejun Heo for_each_worker_pool(pool, gcwq) { 378935b6bb63STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); 379035b6bb63STejun Heo pool->flags &= ~POOL_FREEZING; 379135b6bb63STejun Heo } 3792db7bccf4STejun Heo 3793a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3794a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3795a0a1a5fdSTejun Heo 379658a69cb4STejun Heo if (!cwq || !(wq->flags & WQ_FREEZABLE)) 3797a0a1a5fdSTejun Heo continue; 3798a0a1a5fdSTejun Heo 3799a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 38009f4bd4cdSLai Jiangshan cwq_set_max_active(cwq, wq->saved_max_active); 3801a0a1a5fdSTejun Heo } 38028b03ae3cSTejun Heo 38034ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) 38044ce62e9eSTejun Heo wake_up_worker(pool); 3805e22bee78STejun Heo 38068b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3807a0a1a5fdSTejun Heo } 3808a0a1a5fdSTejun Heo 3809a0a1a5fdSTejun Heo workqueue_freezing = false; 3810a0a1a5fdSTejun Heo out_unlock: 3811a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3812a0a1a5fdSTejun Heo } 3813a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3814a0a1a5fdSTejun Heo 38156ee0578bSSuresh Siddha static int __init init_workqueues(void) 38161da177e4SLinus Torvalds { 3817c34056a3STejun Heo unsigned int cpu; 3818c34056a3STejun Heo 3819b5490077STejun Heo /* make sure we have enough bits for OFFQ CPU number */ 3820b5490077STejun Heo BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_CPU_SHIFT)) < 3821b5490077STejun Heo WORK_CPU_LAST); 3822b5490077STejun Heo 382365758202STejun Heo cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); 3824a5b4e57dSLai Jiangshan hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); 38258b03ae3cSTejun Heo 38268b03ae3cSTejun Heo /* initialize gcwqs */ 3827f3421797STejun Heo for_each_gcwq_cpu(cpu) { 38288b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 38294ce62e9eSTejun Heo struct worker_pool *pool; 38308b03ae3cSTejun Heo 38318b03ae3cSTejun Heo spin_lock_init(&gcwq->lock); 38328b03ae3cSTejun Heo gcwq->cpu = cpu; 38338b03ae3cSTejun Heo 383442f8570fSSasha Levin hash_init(gcwq->busy_hash); 3835c8e55f36STejun Heo 38364ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) { 38374ce62e9eSTejun Heo pool->gcwq = gcwq; 383824647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 38394ce62e9eSTejun Heo INIT_LIST_HEAD(&pool->worklist); 38404ce62e9eSTejun Heo INIT_LIST_HEAD(&pool->idle_list); 3841e22bee78STejun Heo 38424ce62e9eSTejun Heo init_timer_deferrable(&pool->idle_timer); 38434ce62e9eSTejun Heo pool->idle_timer.function = idle_worker_timeout; 38444ce62e9eSTejun Heo pool->idle_timer.data = (unsigned long)pool; 3845e22bee78STejun Heo 38464ce62e9eSTejun Heo setup_timer(&pool->mayday_timer, gcwq_mayday_timeout, 38474ce62e9eSTejun Heo (unsigned long)pool); 38484ce62e9eSTejun Heo 3849b2eb83d1SLai Jiangshan mutex_init(&pool->assoc_mutex); 38504ce62e9eSTejun Heo ida_init(&pool->worker_ida); 38519daf9e67STejun Heo 38529daf9e67STejun Heo /* alloc pool ID */ 38539daf9e67STejun Heo BUG_ON(worker_pool_assign_id(pool)); 38544ce62e9eSTejun Heo } 38558b03ae3cSTejun Heo } 38568b03ae3cSTejun Heo 3857e22bee78STejun Heo /* create the initial worker */ 3858f3421797STejun Heo for_each_online_gcwq_cpu(cpu) { 3859e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 38604ce62e9eSTejun Heo struct worker_pool *pool; 3861e22bee78STejun Heo 38624ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) { 38634ce62e9eSTejun Heo struct worker *worker; 38644ce62e9eSTejun Heo 386524647570STejun Heo if (cpu != WORK_CPU_UNBOUND) 386624647570STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 386724647570STejun Heo 3868bc2ae0f5STejun Heo worker = create_worker(pool); 3869e22bee78STejun Heo BUG_ON(!worker); 3870e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3871e22bee78STejun Heo start_worker(worker); 3872e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3873e22bee78STejun Heo } 38744ce62e9eSTejun Heo } 3875e22bee78STejun Heo 3876d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 38771aabe902SJoonsoo Kim system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 3878d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3879f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3880f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 388124d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 388224d51addSTejun Heo WQ_FREEZABLE, 0); 38831aabe902SJoonsoo Kim BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 3884ae930e0fSTejun Heo !system_unbound_wq || !system_freezable_wq); 38856ee0578bSSuresh Siddha return 0; 38861da177e4SLinus Torvalds } 38876ee0578bSSuresh Siddha early_initcall(init_workqueues); 3888