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> 44e22bee78STejun Heo 45e22bee78STejun Heo #include "workqueue_sched.h" 461da177e4SLinus Torvalds 47c8e55f36STejun Heo enum { 48db7bccf4STejun Heo /* global_cwq flags */ 49e22bee78STejun Heo GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ 50e22bee78STejun Heo GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */ 51e22bee78STejun Heo GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 52db7bccf4STejun Heo GCWQ_FREEZING = 1 << 3, /* freeze in progress */ 53649027d7STejun Heo GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */ 54db7bccf4STejun Heo 55c8e55f36STejun Heo /* worker flags */ 56c8e55f36STejun Heo WORKER_STARTED = 1 << 0, /* started */ 57c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 58c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 59e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 60db7bccf4STejun Heo WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ 61e22bee78STejun Heo WORKER_REBIND = 1 << 5, /* mom is home, come back */ 62fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 63f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 64e22bee78STejun Heo 65fb0e7bebSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | 66f3421797STejun Heo WORKER_CPU_INTENSIVE | WORKER_UNBOUND, 67db7bccf4STejun Heo 68db7bccf4STejun Heo /* gcwq->trustee_state */ 69db7bccf4STejun Heo TRUSTEE_START = 0, /* start */ 70db7bccf4STejun Heo TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ 71db7bccf4STejun Heo TRUSTEE_BUTCHER = 2, /* butcher workers */ 72db7bccf4STejun Heo TRUSTEE_RELEASE = 3, /* release workers */ 73db7bccf4STejun Heo TRUSTEE_DONE = 4, /* trustee is done */ 74c8e55f36STejun Heo 75c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 76c8e55f36STejun Heo BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, 77c8e55f36STejun Heo BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, 78db7bccf4STejun Heo 79e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 80e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 81e22bee78STejun Heo 823233cdbdSTejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, 833233cdbdSTejun Heo /* call for help after 10ms 843233cdbdSTejun Heo (min two ticks) */ 85e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 86e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 87db7bccf4STejun Heo TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ 881da177e4SLinus Torvalds 891da177e4SLinus Torvalds /* 90e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 91e22bee78STejun Heo * all cpus. Give -20. 92e22bee78STejun Heo */ 93e22bee78STejun Heo RESCUER_NICE_LEVEL = -20, 94c8e55f36STejun Heo }; 95c8e55f36STejun Heo 961da177e4SLinus Torvalds /* 974690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 984690c4abSTejun Heo * 99e41e704bSTejun Heo * I: Modifiable by initialization/destruction paths and read-only for 100e41e704bSTejun Heo * everyone else. 1014690c4abSTejun Heo * 102e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 103e22bee78STejun Heo * only be modified and accessed from the local cpu. 104e22bee78STejun Heo * 1058b03ae3cSTejun Heo * L: gcwq->lock protected. Access with gcwq->lock held. 1064690c4abSTejun Heo * 107e22bee78STejun Heo * X: During normal operation, modification requires gcwq->lock and 108e22bee78STejun Heo * should be done only from local cpu. Either disabling preemption 109e22bee78STejun Heo * on local cpu or grabbing gcwq->lock is enough for read access. 110f3421797STejun Heo * If GCWQ_DISASSOCIATED is set, it's identical to L. 111e22bee78STejun Heo * 11273f53c4aSTejun Heo * F: wq->flush_mutex protected. 11373f53c4aSTejun Heo * 1144690c4abSTejun Heo * W: workqueue_lock protected. 1154690c4abSTejun Heo */ 1164690c4abSTejun Heo 1178b03ae3cSTejun Heo struct global_cwq; 118c34056a3STejun Heo 119e22bee78STejun Heo /* 120e22bee78STejun Heo * The poor guys doing the actual heavy lifting. All on-duty workers 121e22bee78STejun Heo * are either serving the manager role, on idle list or on busy hash. 122e22bee78STejun Heo */ 123c34056a3STejun Heo struct worker { 124c8e55f36STejun Heo /* on idle list while idle, on busy hash table while busy */ 125c8e55f36STejun Heo union { 126c8e55f36STejun Heo struct list_head entry; /* L: while idle */ 127c8e55f36STejun Heo struct hlist_node hentry; /* L: while busy */ 128c8e55f36STejun Heo }; 129c8e55f36STejun Heo 130c34056a3STejun Heo struct work_struct *current_work; /* L: work being processed */ 1318cca0eeaSTejun Heo struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ 132affee4b2STejun Heo struct list_head scheduled; /* L: scheduled works */ 133c34056a3STejun Heo struct task_struct *task; /* I: worker task */ 1348b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 135e22bee78STejun Heo /* 64 bytes boundary on 64bit, 32 on 32bit */ 136e22bee78STejun Heo unsigned long last_active; /* L: last active timestamp */ 137e22bee78STejun Heo unsigned int flags; /* X: flags */ 138c34056a3STejun Heo int id; /* I: worker id */ 139e22bee78STejun Heo struct work_struct rebind_work; /* L: rebind worker to cpu */ 140c34056a3STejun Heo }; 141c34056a3STejun Heo 1424690c4abSTejun Heo /* 143e22bee78STejun Heo * Global per-cpu workqueue. There's one and only one for each cpu 144e22bee78STejun Heo * and all works are queued and processed here regardless of their 145e22bee78STejun Heo * target workqueues. 1468b03ae3cSTejun Heo */ 1478b03ae3cSTejun Heo struct global_cwq { 1488b03ae3cSTejun Heo spinlock_t lock; /* the gcwq lock */ 1497e11629dSTejun Heo struct list_head worklist; /* L: list of pending works */ 1508b03ae3cSTejun Heo unsigned int cpu; /* I: the associated cpu */ 151db7bccf4STejun Heo unsigned int flags; /* L: GCWQ_* flags */ 152c8e55f36STejun Heo 153c8e55f36STejun Heo int nr_workers; /* L: total number of workers */ 154c8e55f36STejun Heo int nr_idle; /* L: currently idle ones */ 155c8e55f36STejun Heo 156c8e55f36STejun Heo /* workers are chained either in the idle_list or busy_hash */ 157e22bee78STejun Heo struct list_head idle_list; /* X: list of idle workers */ 158c8e55f36STejun Heo struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; 159c8e55f36STejun Heo /* L: hash of busy workers */ 160c8e55f36STejun Heo 161e22bee78STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 162e22bee78STejun Heo struct timer_list mayday_timer; /* L: SOS timer for dworkers */ 163e22bee78STejun Heo 1648b03ae3cSTejun Heo struct ida worker_ida; /* L: for worker IDs */ 165db7bccf4STejun Heo 166db7bccf4STejun Heo struct task_struct *trustee; /* L: for gcwq shutdown */ 167db7bccf4STejun Heo unsigned int trustee_state; /* L: trustee state */ 168db7bccf4STejun Heo wait_queue_head_t trustee_wait; /* trustee wait */ 169e22bee78STejun Heo struct worker *first_idle; /* L: first idle worker */ 1708b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1718b03ae3cSTejun Heo 1728b03ae3cSTejun Heo /* 173502ca9d8STejun Heo * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of 1740f900049STejun Heo * work_struct->data are used for flags and thus cwqs need to be 1750f900049STejun Heo * aligned at two's power of the number of flag bits. 1761da177e4SLinus Torvalds */ 1771da177e4SLinus Torvalds struct cpu_workqueue_struct { 1788b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 1794690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 18073f53c4aSTejun Heo int work_color; /* L: current color */ 18173f53c4aSTejun Heo int flush_color; /* L: flushing color */ 18273f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 18373f53c4aSTejun Heo /* L: nr of in_flight works */ 1841e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 185a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 1861e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 1870f900049STejun Heo }; 1881da177e4SLinus Torvalds 1891da177e4SLinus Torvalds /* 19073f53c4aSTejun Heo * Structure used to wait for workqueue flush. 19173f53c4aSTejun Heo */ 19273f53c4aSTejun Heo struct wq_flusher { 19373f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 19473f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 19573f53c4aSTejun Heo struct completion done; /* flush completion */ 19673f53c4aSTejun Heo }; 1971da177e4SLinus Torvalds 19873f53c4aSTejun Heo /* 199f2e005aaSTejun Heo * All cpumasks are assumed to be always set on UP and thus can't be 200f2e005aaSTejun Heo * used to determine whether there's something to be done. 201f2e005aaSTejun Heo */ 202f2e005aaSTejun Heo #ifdef CONFIG_SMP 203f2e005aaSTejun Heo typedef cpumask_var_t mayday_mask_t; 204f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) \ 205f2e005aaSTejun Heo cpumask_test_and_set_cpu((cpu), (mask)) 206f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) 207f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) 2089c37547aSTejun Heo #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) 209f2e005aaSTejun Heo #define free_mayday_mask(mask) free_cpumask_var((mask)) 210f2e005aaSTejun Heo #else 211f2e005aaSTejun Heo typedef unsigned long mayday_mask_t; 212f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) 213f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) 214f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) 215f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) true 216f2e005aaSTejun Heo #define free_mayday_mask(mask) do { } while (0) 217f2e005aaSTejun Heo #endif 2181da177e4SLinus Torvalds 2191da177e4SLinus Torvalds /* 2201da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 2211da177e4SLinus Torvalds * per-CPU workqueues: 2221da177e4SLinus Torvalds */ 2231da177e4SLinus Torvalds struct workqueue_struct { 2249c5a2ba7STejun Heo unsigned int flags; /* W: WQ_* flags */ 225bdbc5dd7STejun Heo union { 226bdbc5dd7STejun Heo struct cpu_workqueue_struct __percpu *pcpu; 227bdbc5dd7STejun Heo struct cpu_workqueue_struct *single; 228bdbc5dd7STejun Heo unsigned long v; 229bdbc5dd7STejun Heo } cpu_wq; /* I: cwq's */ 2304690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 23173f53c4aSTejun Heo 23273f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 23373f53c4aSTejun Heo int work_color; /* F: current work color */ 23473f53c4aSTejun Heo int flush_color; /* F: current flush color */ 23573f53c4aSTejun Heo atomic_t nr_cwqs_to_flush; /* flush in progress */ 23673f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 23773f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 23873f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 23973f53c4aSTejun Heo 240f2e005aaSTejun Heo mayday_mask_t mayday_mask; /* cpus requesting rescue */ 241e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 242e22bee78STejun Heo 2439c5a2ba7STejun Heo int nr_drainers; /* W: drain in progress */ 244dcd989cbSTejun Heo int saved_max_active; /* W: saved cwq max_active */ 2454e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2464e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2474e6045f1SJohannes Berg #endif 248b196be89STejun Heo char name[]; /* I: workqueue name */ 2491da177e4SLinus Torvalds }; 2501da177e4SLinus Torvalds 251d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 252d320c038STejun Heo struct workqueue_struct *system_long_wq __read_mostly; 253d320c038STejun Heo struct workqueue_struct *system_nrt_wq __read_mostly; 254f3421797STejun Heo struct workqueue_struct *system_unbound_wq __read_mostly; 25524d51addSTejun Heo struct workqueue_struct *system_freezable_wq __read_mostly; 25662d3c543SAlan Stern struct workqueue_struct *system_nrt_freezable_wq __read_mostly; 257d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 258d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 259d320c038STejun Heo EXPORT_SYMBOL_GPL(system_nrt_wq); 260f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 26124d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 26262d3c543SAlan Stern EXPORT_SYMBOL_GPL(system_nrt_freezable_wq); 263d320c038STejun Heo 26497bd2347STejun Heo #define CREATE_TRACE_POINTS 26597bd2347STejun Heo #include <trace/events/workqueue.h> 26697bd2347STejun Heo 267db7bccf4STejun Heo #define for_each_busy_worker(worker, i, pos, gcwq) \ 268db7bccf4STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ 269db7bccf4STejun Heo hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) 270db7bccf4STejun Heo 271f3421797STejun Heo static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, 272f3421797STejun Heo unsigned int sw) 273f3421797STejun Heo { 274f3421797STejun Heo if (cpu < nr_cpu_ids) { 275f3421797STejun Heo if (sw & 1) { 276f3421797STejun Heo cpu = cpumask_next(cpu, mask); 277f3421797STejun Heo if (cpu < nr_cpu_ids) 278f3421797STejun Heo return cpu; 279f3421797STejun Heo } 280f3421797STejun Heo if (sw & 2) 281f3421797STejun Heo return WORK_CPU_UNBOUND; 282f3421797STejun Heo } 283f3421797STejun Heo return WORK_CPU_NONE; 284f3421797STejun Heo } 285f3421797STejun Heo 286f3421797STejun Heo static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, 287f3421797STejun Heo struct workqueue_struct *wq) 288f3421797STejun Heo { 289f3421797STejun Heo return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); 290f3421797STejun Heo } 291f3421797STejun Heo 29209884951STejun Heo /* 29309884951STejun Heo * CPU iterators 29409884951STejun Heo * 29509884951STejun Heo * An extra gcwq is defined for an invalid cpu number 29609884951STejun Heo * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any 29709884951STejun Heo * specific CPU. The following iterators are similar to 29809884951STejun Heo * for_each_*_cpu() iterators but also considers the unbound gcwq. 29909884951STejun Heo * 30009884951STejun Heo * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND 30109884951STejun Heo * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND 30209884951STejun Heo * for_each_cwq_cpu() : possible CPUs for bound workqueues, 30309884951STejun Heo * WORK_CPU_UNBOUND for unbound workqueues 30409884951STejun Heo */ 305f3421797STejun Heo #define for_each_gcwq_cpu(cpu) \ 306f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ 307f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 308f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) 309f3421797STejun Heo 310f3421797STejun Heo #define for_each_online_gcwq_cpu(cpu) \ 311f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ 312f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 313f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) 314f3421797STejun Heo 315f3421797STejun Heo #define for_each_cwq_cpu(cpu, wq) \ 316f3421797STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ 317f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 318f3421797STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) 319f3421797STejun Heo 320dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 321dc186ad7SThomas Gleixner 322dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 323dc186ad7SThomas Gleixner 32499777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 32599777288SStanislaw Gruszka { 32699777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 32799777288SStanislaw Gruszka } 32899777288SStanislaw Gruszka 329dc186ad7SThomas Gleixner /* 330dc186ad7SThomas Gleixner * fixup_init is called when: 331dc186ad7SThomas Gleixner * - an active object is initialized 332dc186ad7SThomas Gleixner */ 333dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 334dc186ad7SThomas Gleixner { 335dc186ad7SThomas Gleixner struct work_struct *work = addr; 336dc186ad7SThomas Gleixner 337dc186ad7SThomas Gleixner switch (state) { 338dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 339dc186ad7SThomas Gleixner cancel_work_sync(work); 340dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 341dc186ad7SThomas Gleixner return 1; 342dc186ad7SThomas Gleixner default: 343dc186ad7SThomas Gleixner return 0; 344dc186ad7SThomas Gleixner } 345dc186ad7SThomas Gleixner } 346dc186ad7SThomas Gleixner 347dc186ad7SThomas Gleixner /* 348dc186ad7SThomas Gleixner * fixup_activate is called when: 349dc186ad7SThomas Gleixner * - an active object is activated 350dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 351dc186ad7SThomas Gleixner */ 352dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 353dc186ad7SThomas Gleixner { 354dc186ad7SThomas Gleixner struct work_struct *work = addr; 355dc186ad7SThomas Gleixner 356dc186ad7SThomas Gleixner switch (state) { 357dc186ad7SThomas Gleixner 358dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 359dc186ad7SThomas Gleixner /* 360dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 361dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 362dc186ad7SThomas Gleixner * is tracked in the object tracker. 363dc186ad7SThomas Gleixner */ 36422df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 365dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 366dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 367dc186ad7SThomas Gleixner return 0; 368dc186ad7SThomas Gleixner } 369dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 370dc186ad7SThomas Gleixner return 0; 371dc186ad7SThomas Gleixner 372dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 373dc186ad7SThomas Gleixner WARN_ON(1); 374dc186ad7SThomas Gleixner 375dc186ad7SThomas Gleixner default: 376dc186ad7SThomas Gleixner return 0; 377dc186ad7SThomas Gleixner } 378dc186ad7SThomas Gleixner } 379dc186ad7SThomas Gleixner 380dc186ad7SThomas Gleixner /* 381dc186ad7SThomas Gleixner * fixup_free is called when: 382dc186ad7SThomas Gleixner * - an active object is freed 383dc186ad7SThomas Gleixner */ 384dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 385dc186ad7SThomas Gleixner { 386dc186ad7SThomas Gleixner struct work_struct *work = addr; 387dc186ad7SThomas Gleixner 388dc186ad7SThomas Gleixner switch (state) { 389dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 390dc186ad7SThomas Gleixner cancel_work_sync(work); 391dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 392dc186ad7SThomas Gleixner return 1; 393dc186ad7SThomas Gleixner default: 394dc186ad7SThomas Gleixner return 0; 395dc186ad7SThomas Gleixner } 396dc186ad7SThomas Gleixner } 397dc186ad7SThomas Gleixner 398dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 399dc186ad7SThomas Gleixner .name = "work_struct", 40099777288SStanislaw Gruszka .debug_hint = work_debug_hint, 401dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 402dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 403dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 404dc186ad7SThomas Gleixner }; 405dc186ad7SThomas Gleixner 406dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 407dc186ad7SThomas Gleixner { 408dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 409dc186ad7SThomas Gleixner } 410dc186ad7SThomas Gleixner 411dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 412dc186ad7SThomas Gleixner { 413dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 414dc186ad7SThomas Gleixner } 415dc186ad7SThomas Gleixner 416dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 417dc186ad7SThomas Gleixner { 418dc186ad7SThomas Gleixner if (onstack) 419dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 420dc186ad7SThomas Gleixner else 421dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 422dc186ad7SThomas Gleixner } 423dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 424dc186ad7SThomas Gleixner 425dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 426dc186ad7SThomas Gleixner { 427dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 428dc186ad7SThomas Gleixner } 429dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 430dc186ad7SThomas Gleixner 431dc186ad7SThomas Gleixner #else 432dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 433dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 434dc186ad7SThomas Gleixner #endif 435dc186ad7SThomas Gleixner 43695402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 43795402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 4381da177e4SLinus Torvalds static LIST_HEAD(workqueues); 439a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 4401da177e4SLinus Torvalds 44114441960SOleg Nesterov /* 442e22bee78STejun Heo * The almighty global cpu workqueues. nr_running is the only field 443e22bee78STejun Heo * which is expected to be used frequently by other cpus via 444e22bee78STejun Heo * try_to_wake_up(). Put it in a separate cacheline. 44514441960SOleg Nesterov */ 4468b03ae3cSTejun Heo static DEFINE_PER_CPU(struct global_cwq, global_cwq); 447e22bee78STejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); 448f756d5e2SNathan Lynch 449f3421797STejun Heo /* 450f3421797STejun Heo * Global cpu workqueue and nr_running counter for unbound gcwq. The 451f3421797STejun Heo * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its 452f3421797STejun Heo * workers have WORKER_UNBOUND set. 453f3421797STejun Heo */ 454f3421797STejun Heo static struct global_cwq unbound_global_cwq; 455f3421797STejun Heo static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ 456f3421797STejun Heo 457c34056a3STejun Heo static int worker_thread(void *__worker); 4581da177e4SLinus Torvalds 4598b03ae3cSTejun Heo static struct global_cwq *get_gcwq(unsigned int cpu) 4601da177e4SLinus Torvalds { 461f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 4628b03ae3cSTejun Heo return &per_cpu(global_cwq, cpu); 463f3421797STejun Heo else 464f3421797STejun Heo return &unbound_global_cwq; 4651da177e4SLinus Torvalds } 4661da177e4SLinus Torvalds 467e22bee78STejun Heo static atomic_t *get_gcwq_nr_running(unsigned int cpu) 468b1f4ec17SOleg Nesterov { 469f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 470e22bee78STejun Heo return &per_cpu(gcwq_nr_running, cpu); 471f3421797STejun Heo else 472f3421797STejun Heo return &unbound_gcwq_nr_running; 473b1f4ec17SOleg Nesterov } 474b1f4ec17SOleg Nesterov 4754690c4abSTejun Heo static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, 4764690c4abSTejun Heo struct workqueue_struct *wq) 477a848e3b6SOleg Nesterov { 478f3421797STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 479e06ffa1eSLai Jiangshan if (likely(cpu < nr_cpu_ids)) 480bdbc5dd7STejun Heo return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); 481f3421797STejun Heo } else if (likely(cpu == WORK_CPU_UNBOUND)) 482f3421797STejun Heo return wq->cpu_wq.single; 483f3421797STejun Heo return NULL; 484f3421797STejun Heo } 485a848e3b6SOleg Nesterov 48673f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 48773f53c4aSTejun Heo { 48873f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 48973f53c4aSTejun Heo } 49073f53c4aSTejun Heo 49173f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 49273f53c4aSTejun Heo { 49373f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 49473f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 49573f53c4aSTejun Heo } 49673f53c4aSTejun Heo 49773f53c4aSTejun Heo static int work_next_color(int color) 49873f53c4aSTejun Heo { 49973f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 5001da177e4SLinus Torvalds } 5011da177e4SLinus Torvalds 5024594bf15SDavid Howells /* 503e120153dSTejun Heo * A work's data points to the cwq with WORK_STRUCT_CWQ set while the 504e120153dSTejun Heo * work is on queue. Once execution starts, WORK_STRUCT_CWQ is 505e120153dSTejun Heo * cleared and the work data contains the cpu number it was last on. 5067a22ad75STejun Heo * 5077a22ad75STejun Heo * set_work_{cwq|cpu}() and clear_work_data() can be used to set the 5087a22ad75STejun Heo * cwq, cpu or clear work->data. These functions should only be 5097a22ad75STejun Heo * called while the work is owned - ie. while the PENDING bit is set. 5107a22ad75STejun Heo * 5117a22ad75STejun Heo * get_work_[g]cwq() can be used to obtain the gcwq or cwq 5127a22ad75STejun Heo * corresponding to a work. gcwq is available once the work has been 5137a22ad75STejun Heo * queued anywhere after initialization. cwq is available only from 5147a22ad75STejun Heo * queueing until execution starts. 5154594bf15SDavid Howells */ 5167a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 5177a22ad75STejun Heo unsigned long flags) 5187a22ad75STejun Heo { 5197a22ad75STejun Heo BUG_ON(!work_pending(work)); 5207a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 5217a22ad75STejun Heo } 5227a22ad75STejun Heo 5237a22ad75STejun Heo static void set_work_cwq(struct work_struct *work, 5244690c4abSTejun Heo struct cpu_workqueue_struct *cwq, 5254690c4abSTejun Heo unsigned long extra_flags) 526365970a1SDavid Howells { 5277a22ad75STejun Heo set_work_data(work, (unsigned long)cwq, 528e120153dSTejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); 529365970a1SDavid Howells } 530365970a1SDavid Howells 5317a22ad75STejun Heo static void set_work_cpu(struct work_struct *work, unsigned int cpu) 5324d707b9fSOleg Nesterov { 5337a22ad75STejun Heo set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); 5344d707b9fSOleg Nesterov } 5354d707b9fSOleg Nesterov 5367a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 537365970a1SDavid Howells { 5387a22ad75STejun Heo set_work_data(work, WORK_STRUCT_NO_CPU, 0); 5397a22ad75STejun Heo } 5407a22ad75STejun Heo 5417a22ad75STejun Heo static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) 5427a22ad75STejun Heo { 543e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5447a22ad75STejun Heo 545e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 546e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 547e120153dSTejun Heo else 548e120153dSTejun Heo return NULL; 5497a22ad75STejun Heo } 5507a22ad75STejun Heo 5517a22ad75STejun Heo static struct global_cwq *get_work_gcwq(struct work_struct *work) 5527a22ad75STejun Heo { 553e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5547a22ad75STejun Heo unsigned int cpu; 5557a22ad75STejun Heo 556e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 557e120153dSTejun Heo return ((struct cpu_workqueue_struct *) 558e120153dSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; 5597a22ad75STejun Heo 5607a22ad75STejun Heo cpu = data >> WORK_STRUCT_FLAG_BITS; 561bdbc5dd7STejun Heo if (cpu == WORK_CPU_NONE) 5627a22ad75STejun Heo return NULL; 5637a22ad75STejun Heo 564f3421797STejun Heo BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); 5657a22ad75STejun Heo return get_gcwq(cpu); 566365970a1SDavid Howells } 567365970a1SDavid Howells 568e22bee78STejun Heo /* 569e22bee78STejun Heo * Policy functions. These define the policies on how the global 570e22bee78STejun Heo * worker pool is managed. Unless noted otherwise, these functions 571e22bee78STejun Heo * assume that they're being called with gcwq->lock held. 572e22bee78STejun Heo */ 573e22bee78STejun Heo 574649027d7STejun Heo static bool __need_more_worker(struct global_cwq *gcwq) 575649027d7STejun Heo { 576649027d7STejun Heo return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || 577649027d7STejun Heo gcwq->flags & GCWQ_HIGHPRI_PENDING; 578649027d7STejun Heo } 579649027d7STejun Heo 580e22bee78STejun Heo /* 581e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 582e22bee78STejun Heo * running workers. 583e22bee78STejun Heo */ 584e22bee78STejun Heo static bool need_more_worker(struct global_cwq *gcwq) 585e22bee78STejun Heo { 586649027d7STejun Heo return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); 587e22bee78STejun Heo } 588e22bee78STejun Heo 589e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 590e22bee78STejun Heo static bool may_start_working(struct global_cwq *gcwq) 591e22bee78STejun Heo { 592e22bee78STejun Heo return gcwq->nr_idle; 593e22bee78STejun Heo } 594e22bee78STejun Heo 595e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 596e22bee78STejun Heo static bool keep_working(struct global_cwq *gcwq) 597e22bee78STejun Heo { 598e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 599e22bee78STejun Heo 60030310045STejun Heo return !list_empty(&gcwq->worklist) && 60130310045STejun Heo (atomic_read(nr_running) <= 1 || 60230310045STejun Heo gcwq->flags & GCWQ_HIGHPRI_PENDING); 603e22bee78STejun Heo } 604e22bee78STejun Heo 605e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 606e22bee78STejun Heo static bool need_to_create_worker(struct global_cwq *gcwq) 607e22bee78STejun Heo { 608e22bee78STejun Heo return need_more_worker(gcwq) && !may_start_working(gcwq); 609e22bee78STejun Heo } 610e22bee78STejun Heo 611e22bee78STejun Heo /* Do I need to be the manager? */ 612e22bee78STejun Heo static bool need_to_manage_workers(struct global_cwq *gcwq) 613e22bee78STejun Heo { 614e22bee78STejun Heo return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; 615e22bee78STejun Heo } 616e22bee78STejun Heo 617e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 618e22bee78STejun Heo static bool too_many_workers(struct global_cwq *gcwq) 619e22bee78STejun Heo { 620e22bee78STejun Heo bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; 621e22bee78STejun Heo int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ 622e22bee78STejun Heo int nr_busy = gcwq->nr_workers - nr_idle; 623e22bee78STejun Heo 624e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 625e22bee78STejun Heo } 626e22bee78STejun Heo 627e22bee78STejun Heo /* 628e22bee78STejun Heo * Wake up functions. 629e22bee78STejun Heo */ 630e22bee78STejun Heo 6317e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 6327e11629dSTejun Heo static struct worker *first_worker(struct global_cwq *gcwq) 6337e11629dSTejun Heo { 6347e11629dSTejun Heo if (unlikely(list_empty(&gcwq->idle_list))) 6357e11629dSTejun Heo return NULL; 6367e11629dSTejun Heo 6377e11629dSTejun Heo return list_first_entry(&gcwq->idle_list, struct worker, entry); 6387e11629dSTejun Heo } 6397e11629dSTejun Heo 6407e11629dSTejun Heo /** 6417e11629dSTejun Heo * wake_up_worker - wake up an idle worker 6427e11629dSTejun Heo * @gcwq: gcwq to wake worker for 6437e11629dSTejun Heo * 6447e11629dSTejun Heo * Wake up the first idle worker of @gcwq. 6457e11629dSTejun Heo * 6467e11629dSTejun Heo * CONTEXT: 6477e11629dSTejun Heo * spin_lock_irq(gcwq->lock). 6487e11629dSTejun Heo */ 6497e11629dSTejun Heo static void wake_up_worker(struct global_cwq *gcwq) 6507e11629dSTejun Heo { 6517e11629dSTejun Heo struct worker *worker = first_worker(gcwq); 6527e11629dSTejun Heo 6537e11629dSTejun Heo if (likely(worker)) 6547e11629dSTejun Heo wake_up_process(worker->task); 6557e11629dSTejun Heo } 6567e11629dSTejun Heo 6574690c4abSTejun Heo /** 658e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 659e22bee78STejun Heo * @task: task waking up 660e22bee78STejun Heo * @cpu: CPU @task is waking up to 661e22bee78STejun Heo * 662e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 663e22bee78STejun Heo * being awoken. 664e22bee78STejun Heo * 665e22bee78STejun Heo * CONTEXT: 666e22bee78STejun Heo * spin_lock_irq(rq->lock) 667e22bee78STejun Heo */ 668e22bee78STejun Heo void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) 669e22bee78STejun Heo { 670e22bee78STejun Heo struct worker *worker = kthread_data(task); 671e22bee78STejun Heo 6722d64672eSSteven Rostedt if (!(worker->flags & WORKER_NOT_RUNNING)) 673e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(cpu)); 674e22bee78STejun Heo } 675e22bee78STejun Heo 676e22bee78STejun Heo /** 677e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 678e22bee78STejun Heo * @task: task going to sleep 679e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 680e22bee78STejun Heo * 681e22bee78STejun Heo * This function is called during schedule() when a busy worker is 682e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 683e22bee78STejun Heo * returning pointer to its task. 684e22bee78STejun Heo * 685e22bee78STejun Heo * CONTEXT: 686e22bee78STejun Heo * spin_lock_irq(rq->lock) 687e22bee78STejun Heo * 688e22bee78STejun Heo * RETURNS: 689e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 690e22bee78STejun Heo */ 691e22bee78STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, 692e22bee78STejun Heo unsigned int cpu) 693e22bee78STejun Heo { 694e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 695e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 696e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(cpu); 697e22bee78STejun Heo 6982d64672eSSteven Rostedt if (worker->flags & WORKER_NOT_RUNNING) 699e22bee78STejun Heo return NULL; 700e22bee78STejun Heo 701e22bee78STejun Heo /* this can only happen on the local cpu */ 702e22bee78STejun Heo BUG_ON(cpu != raw_smp_processor_id()); 703e22bee78STejun Heo 704e22bee78STejun Heo /* 705e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 706e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 707e22bee78STejun Heo * Please read comment there. 708e22bee78STejun Heo * 709e22bee78STejun Heo * NOT_RUNNING is clear. This means that trustee is not in 710e22bee78STejun Heo * charge and we're running on the local cpu w/ rq lock held 711e22bee78STejun Heo * and preemption disabled, which in turn means that none else 712e22bee78STejun Heo * could be manipulating idle_list, so dereferencing idle_list 713e22bee78STejun Heo * without gcwq lock is safe. 714e22bee78STejun Heo */ 715e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) 716e22bee78STejun Heo to_wakeup = first_worker(gcwq); 717e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 718e22bee78STejun Heo } 719e22bee78STejun Heo 720e22bee78STejun Heo /** 721e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 722cb444766STejun Heo * @worker: self 723d302f017STejun Heo * @flags: flags to set 724d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 725d302f017STejun Heo * 726e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 727e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 728e22bee78STejun Heo * woken up. 729d302f017STejun Heo * 730cb444766STejun Heo * CONTEXT: 731cb444766STejun Heo * spin_lock_irq(gcwq->lock) 732d302f017STejun Heo */ 733d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 734d302f017STejun Heo bool wakeup) 735d302f017STejun Heo { 736e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 737e22bee78STejun Heo 738cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 739cb444766STejun Heo 740e22bee78STejun Heo /* 741e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 742e22bee78STejun Heo * wake up an idle worker as necessary if requested by 743e22bee78STejun Heo * @wakeup. 744e22bee78STejun Heo */ 745e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 746e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 747e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 748e22bee78STejun Heo 749e22bee78STejun Heo if (wakeup) { 750e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && 751e22bee78STejun Heo !list_empty(&gcwq->worklist)) 752e22bee78STejun Heo wake_up_worker(gcwq); 753e22bee78STejun Heo } else 754e22bee78STejun Heo atomic_dec(nr_running); 755e22bee78STejun Heo } 756e22bee78STejun Heo 757d302f017STejun Heo worker->flags |= flags; 758d302f017STejun Heo } 759d302f017STejun Heo 760d302f017STejun Heo /** 761e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 762cb444766STejun Heo * @worker: self 763d302f017STejun Heo * @flags: flags to clear 764d302f017STejun Heo * 765e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 766d302f017STejun Heo * 767cb444766STejun Heo * CONTEXT: 768cb444766STejun Heo * spin_lock_irq(gcwq->lock) 769d302f017STejun Heo */ 770d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 771d302f017STejun Heo { 772e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 773e22bee78STejun Heo unsigned int oflags = worker->flags; 774e22bee78STejun Heo 775cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 776cb444766STejun Heo 777d302f017STejun Heo worker->flags &= ~flags; 778e22bee78STejun Heo 77942c025f3STejun Heo /* 78042c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 78142c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 78242c025f3STejun Heo * of multiple flags, not a single flag. 78342c025f3STejun Heo */ 784e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 785e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 786e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(gcwq->cpu)); 787d302f017STejun Heo } 788d302f017STejun Heo 789d302f017STejun Heo /** 790c8e55f36STejun Heo * busy_worker_head - return the busy hash head for a work 791c8e55f36STejun Heo * @gcwq: gcwq of interest 792c8e55f36STejun Heo * @work: work to be hashed 793c8e55f36STejun Heo * 794c8e55f36STejun Heo * Return hash head of @gcwq for @work. 795c8e55f36STejun Heo * 796c8e55f36STejun Heo * CONTEXT: 797c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 798c8e55f36STejun Heo * 799c8e55f36STejun Heo * RETURNS: 800c8e55f36STejun Heo * Pointer to the hash head. 801c8e55f36STejun Heo */ 802c8e55f36STejun Heo static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, 803c8e55f36STejun Heo struct work_struct *work) 804c8e55f36STejun Heo { 805c8e55f36STejun Heo const int base_shift = ilog2(sizeof(struct work_struct)); 806c8e55f36STejun Heo unsigned long v = (unsigned long)work; 807c8e55f36STejun Heo 808c8e55f36STejun Heo /* simple shift and fold hash, do we need something better? */ 809c8e55f36STejun Heo v >>= base_shift; 810c8e55f36STejun Heo v += v >> BUSY_WORKER_HASH_ORDER; 811c8e55f36STejun Heo v &= BUSY_WORKER_HASH_MASK; 812c8e55f36STejun Heo 813c8e55f36STejun Heo return &gcwq->busy_hash[v]; 814c8e55f36STejun Heo } 815c8e55f36STejun Heo 816c8e55f36STejun Heo /** 8178cca0eeaSTejun Heo * __find_worker_executing_work - find worker which is executing a work 8188cca0eeaSTejun Heo * @gcwq: gcwq of interest 8198cca0eeaSTejun Heo * @bwh: hash head as returned by busy_worker_head() 8208cca0eeaSTejun Heo * @work: work to find worker for 8218cca0eeaSTejun Heo * 8228cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. @bwh should be 8238cca0eeaSTejun Heo * the hash head obtained by calling busy_worker_head() with the same 8248cca0eeaSTejun Heo * work. 8258cca0eeaSTejun Heo * 8268cca0eeaSTejun Heo * CONTEXT: 8278cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8288cca0eeaSTejun Heo * 8298cca0eeaSTejun Heo * RETURNS: 8308cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8318cca0eeaSTejun Heo * otherwise. 8328cca0eeaSTejun Heo */ 8338cca0eeaSTejun Heo static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, 8348cca0eeaSTejun Heo struct hlist_head *bwh, 8358cca0eeaSTejun Heo struct work_struct *work) 8368cca0eeaSTejun Heo { 8378cca0eeaSTejun Heo struct worker *worker; 8388cca0eeaSTejun Heo struct hlist_node *tmp; 8398cca0eeaSTejun Heo 8408cca0eeaSTejun Heo hlist_for_each_entry(worker, tmp, bwh, hentry) 8418cca0eeaSTejun Heo if (worker->current_work == work) 8428cca0eeaSTejun Heo return worker; 8438cca0eeaSTejun Heo return NULL; 8448cca0eeaSTejun Heo } 8458cca0eeaSTejun Heo 8468cca0eeaSTejun Heo /** 8478cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 8488cca0eeaSTejun Heo * @gcwq: gcwq of interest 8498cca0eeaSTejun Heo * @work: work to find worker for 8508cca0eeaSTejun Heo * 8518cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. This function is 8528cca0eeaSTejun Heo * identical to __find_worker_executing_work() except that this 8538cca0eeaSTejun Heo * function calculates @bwh itself. 8548cca0eeaSTejun Heo * 8558cca0eeaSTejun Heo * CONTEXT: 8568cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8578cca0eeaSTejun Heo * 8588cca0eeaSTejun Heo * RETURNS: 8598cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8608cca0eeaSTejun Heo * otherwise. 8618cca0eeaSTejun Heo */ 8628cca0eeaSTejun Heo static struct worker *find_worker_executing_work(struct global_cwq *gcwq, 8638cca0eeaSTejun Heo struct work_struct *work) 8648cca0eeaSTejun Heo { 8658cca0eeaSTejun Heo return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), 8668cca0eeaSTejun Heo work); 8678cca0eeaSTejun Heo } 8688cca0eeaSTejun Heo 8698cca0eeaSTejun Heo /** 870649027d7STejun Heo * gcwq_determine_ins_pos - find insertion position 871649027d7STejun Heo * @gcwq: gcwq of interest 872649027d7STejun Heo * @cwq: cwq a work is being queued for 873649027d7STejun Heo * 874649027d7STejun Heo * A work for @cwq is about to be queued on @gcwq, determine insertion 875649027d7STejun Heo * position for the work. If @cwq is for HIGHPRI wq, the work is 876649027d7STejun Heo * queued at the head of the queue but in FIFO order with respect to 877649027d7STejun Heo * other HIGHPRI works; otherwise, at the end of the queue. This 878649027d7STejun Heo * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that 879649027d7STejun Heo * there are HIGHPRI works pending. 880649027d7STejun Heo * 881649027d7STejun Heo * CONTEXT: 882649027d7STejun Heo * spin_lock_irq(gcwq->lock). 883649027d7STejun Heo * 884649027d7STejun Heo * RETURNS: 885649027d7STejun Heo * Pointer to inserstion position. 886649027d7STejun Heo */ 887649027d7STejun Heo static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, 8881da177e4SLinus Torvalds struct cpu_workqueue_struct *cwq) 8891da177e4SLinus Torvalds { 890649027d7STejun Heo struct work_struct *twork; 8911da177e4SLinus Torvalds 892649027d7STejun Heo if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) 893649027d7STejun Heo return &gcwq->worklist; 8941da177e4SLinus Torvalds 895649027d7STejun Heo list_for_each_entry(twork, &gcwq->worklist, entry) { 896649027d7STejun Heo struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); 897649027d7STejun Heo 898649027d7STejun Heo if (!(tcwq->wq->flags & WQ_HIGHPRI)) 899649027d7STejun Heo break; 9001da177e4SLinus Torvalds } 9011da177e4SLinus Torvalds 902649027d7STejun Heo gcwq->flags |= GCWQ_HIGHPRI_PENDING; 903649027d7STejun Heo return &twork->entry; 904649027d7STejun Heo } 905649027d7STejun Heo 906649027d7STejun Heo /** 9077e11629dSTejun Heo * insert_work - insert a work into gcwq 9084690c4abSTejun Heo * @cwq: cwq @work belongs to 9094690c4abSTejun Heo * @work: work to insert 9104690c4abSTejun Heo * @head: insertion point 9114690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 9124690c4abSTejun Heo * 9137e11629dSTejun Heo * Insert @work which belongs to @cwq into @gcwq after @head. 9147e11629dSTejun Heo * @extra_flags is or'd to work_struct flags. 9154690c4abSTejun Heo * 9164690c4abSTejun Heo * CONTEXT: 9178b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 9181da177e4SLinus Torvalds */ 919b89deed3SOleg Nesterov static void insert_work(struct cpu_workqueue_struct *cwq, 9204690c4abSTejun Heo struct work_struct *work, struct list_head *head, 9214690c4abSTejun Heo unsigned int extra_flags) 922b89deed3SOleg Nesterov { 923e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 924e1d8aa9fSFrederic Weisbecker 9254690c4abSTejun Heo /* we own @work, set data and link */ 9267a22ad75STejun Heo set_work_cwq(work, cwq, extra_flags); 9274690c4abSTejun Heo 9286e84d644SOleg Nesterov /* 9296e84d644SOleg Nesterov * Ensure that we get the right work->data if we see the 9306e84d644SOleg Nesterov * result of list_add() below, see try_to_grab_pending(). 9316e84d644SOleg Nesterov */ 9326e84d644SOleg Nesterov smp_wmb(); 9334690c4abSTejun Heo 9341a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 935e22bee78STejun Heo 936e22bee78STejun Heo /* 937e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 938e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 939e22bee78STejun Heo * lying around lazily while there are works to be processed. 940e22bee78STejun Heo */ 941e22bee78STejun Heo smp_mb(); 942e22bee78STejun Heo 943649027d7STejun Heo if (__need_more_worker(gcwq)) 944e22bee78STejun Heo wake_up_worker(gcwq); 945b89deed3SOleg Nesterov } 946b89deed3SOleg Nesterov 947c8efcc25STejun Heo /* 948c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 949c8efcc25STejun Heo * same workqueue. This is rather expensive and should only be used from 950c8efcc25STejun Heo * cold paths. 951c8efcc25STejun Heo */ 952c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 953c8efcc25STejun Heo { 954c8efcc25STejun Heo unsigned long flags; 955c8efcc25STejun Heo unsigned int cpu; 956c8efcc25STejun Heo 957c8efcc25STejun Heo for_each_gcwq_cpu(cpu) { 958c8efcc25STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 959c8efcc25STejun Heo struct worker *worker; 960c8efcc25STejun Heo struct hlist_node *pos; 961c8efcc25STejun Heo int i; 962c8efcc25STejun Heo 963c8efcc25STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 964c8efcc25STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 965c8efcc25STejun Heo if (worker->task != current) 966c8efcc25STejun Heo continue; 967c8efcc25STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 968c8efcc25STejun Heo /* 969c8efcc25STejun Heo * I'm @worker, no locking necessary. See if @work 970c8efcc25STejun Heo * is headed to the same workqueue. 971c8efcc25STejun Heo */ 972c8efcc25STejun Heo return worker->current_cwq->wq == wq; 973c8efcc25STejun Heo } 974c8efcc25STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 975c8efcc25STejun Heo } 976c8efcc25STejun Heo return false; 977c8efcc25STejun Heo } 978c8efcc25STejun Heo 9794690c4abSTejun Heo static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 9801da177e4SLinus Torvalds struct work_struct *work) 9811da177e4SLinus Torvalds { 982502ca9d8STejun Heo struct global_cwq *gcwq; 983502ca9d8STejun Heo struct cpu_workqueue_struct *cwq; 9841e19ffc6STejun Heo struct list_head *worklist; 9858a2e8e5dSTejun Heo unsigned int work_flags; 9861da177e4SLinus Torvalds unsigned long flags; 9871da177e4SLinus Torvalds 988dc186ad7SThomas Gleixner debug_work_activate(work); 9891e19ffc6STejun Heo 990c8efcc25STejun Heo /* if dying, only works from the same workqueue are allowed */ 9919c5a2ba7STejun Heo if (unlikely(wq->flags & WQ_DRAINING) && 992c8efcc25STejun Heo WARN_ON_ONCE(!is_chained_work(wq))) 993e41e704bSTejun Heo return; 994e41e704bSTejun Heo 995c7fc77f7STejun Heo /* determine gcwq to use */ 996c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 997c7fc77f7STejun Heo struct global_cwq *last_gcwq; 998c7fc77f7STejun Heo 999f3421797STejun Heo if (unlikely(cpu == WORK_CPU_UNBOUND)) 1000f3421797STejun Heo cpu = raw_smp_processor_id(); 1001f3421797STejun Heo 100218aa9effSTejun Heo /* 100318aa9effSTejun Heo * It's multi cpu. If @wq is non-reentrant and @work 100418aa9effSTejun Heo * was previously on a different cpu, it might still 100518aa9effSTejun Heo * be running there, in which case the work needs to 100618aa9effSTejun Heo * be queued on that cpu to guarantee non-reentrance. 100718aa9effSTejun Heo */ 1008502ca9d8STejun Heo gcwq = get_gcwq(cpu); 100918aa9effSTejun Heo if (wq->flags & WQ_NON_REENTRANT && 101018aa9effSTejun Heo (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { 101118aa9effSTejun Heo struct worker *worker; 101218aa9effSTejun Heo 101318aa9effSTejun Heo spin_lock_irqsave(&last_gcwq->lock, flags); 101418aa9effSTejun Heo 101518aa9effSTejun Heo worker = find_worker_executing_work(last_gcwq, work); 101618aa9effSTejun Heo 101718aa9effSTejun Heo if (worker && worker->current_cwq->wq == wq) 101818aa9effSTejun Heo gcwq = last_gcwq; 101918aa9effSTejun Heo else { 102018aa9effSTejun Heo /* meh... not running there, queue here */ 102118aa9effSTejun Heo spin_unlock_irqrestore(&last_gcwq->lock, flags); 102218aa9effSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 102318aa9effSTejun Heo } 102418aa9effSTejun Heo } else 10258b03ae3cSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 1026f3421797STejun Heo } else { 1027f3421797STejun Heo gcwq = get_gcwq(WORK_CPU_UNBOUND); 1028f3421797STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 1029502ca9d8STejun Heo } 1030502ca9d8STejun Heo 1031502ca9d8STejun Heo /* gcwq determined, get cwq and queue */ 1032502ca9d8STejun Heo cwq = get_cwq(gcwq->cpu, wq); 1033cdadf009STejun Heo trace_workqueue_queue_work(cpu, cwq, work); 1034502ca9d8STejun Heo 1035f5b2552bSDan Carpenter if (WARN_ON(!list_empty(&work->entry))) { 1036f5b2552bSDan Carpenter spin_unlock_irqrestore(&gcwq->lock, flags); 1037f5b2552bSDan Carpenter return; 1038f5b2552bSDan Carpenter } 10391e19ffc6STejun Heo 104073f53c4aSTejun Heo cwq->nr_in_flight[cwq->work_color]++; 10418a2e8e5dSTejun Heo work_flags = work_color_to_flags(cwq->work_color); 10421e19ffc6STejun Heo 10431e19ffc6STejun Heo if (likely(cwq->nr_active < cwq->max_active)) { 1044cdadf009STejun Heo trace_workqueue_activate_work(work); 10451e19ffc6STejun Heo cwq->nr_active++; 1046649027d7STejun Heo worklist = gcwq_determine_ins_pos(gcwq, cwq); 10478a2e8e5dSTejun Heo } else { 10488a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 10491e19ffc6STejun Heo worklist = &cwq->delayed_works; 10508a2e8e5dSTejun Heo } 10511e19ffc6STejun Heo 10528a2e8e5dSTejun Heo insert_work(cwq, work, worklist, work_flags); 10531e19ffc6STejun Heo 10548b03ae3cSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 10551da177e4SLinus Torvalds } 10561da177e4SLinus Torvalds 10570fcb78c2SRolf Eike Beer /** 10580fcb78c2SRolf Eike Beer * queue_work - queue work on a workqueue 10590fcb78c2SRolf Eike Beer * @wq: workqueue to use 10600fcb78c2SRolf Eike Beer * @work: work to queue 10610fcb78c2SRolf Eike Beer * 1062057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10631da177e4SLinus Torvalds * 106400dfcaf7SOleg Nesterov * We queue the work to the CPU on which it was submitted, but if the CPU dies 106500dfcaf7SOleg Nesterov * it can be processed by another CPU. 10661da177e4SLinus Torvalds */ 10677ad5b3a5SHarvey Harrison int queue_work(struct workqueue_struct *wq, struct work_struct *work) 10681da177e4SLinus Torvalds { 1069ef1ca236SOleg Nesterov int ret; 10701da177e4SLinus Torvalds 1071ef1ca236SOleg Nesterov ret = queue_work_on(get_cpu(), wq, work); 1072a848e3b6SOleg Nesterov put_cpu(); 1073ef1ca236SOleg Nesterov 10741da177e4SLinus Torvalds return ret; 10751da177e4SLinus Torvalds } 1076ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_work); 10771da177e4SLinus Torvalds 1078c1a220e7SZhang Rui /** 1079c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1080c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1081c1a220e7SZhang Rui * @wq: workqueue to use 1082c1a220e7SZhang Rui * @work: work to queue 1083c1a220e7SZhang Rui * 1084c1a220e7SZhang Rui * Returns 0 if @work was already on a queue, non-zero otherwise. 1085c1a220e7SZhang Rui * 1086c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1087c1a220e7SZhang Rui * can't go away. 1088c1a220e7SZhang Rui */ 1089c1a220e7SZhang Rui int 1090c1a220e7SZhang Rui queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) 1091c1a220e7SZhang Rui { 1092c1a220e7SZhang Rui int ret = 0; 1093c1a220e7SZhang Rui 109422df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 10954690c4abSTejun Heo __queue_work(cpu, wq, work); 1096c1a220e7SZhang Rui ret = 1; 1097c1a220e7SZhang Rui } 1098c1a220e7SZhang Rui return ret; 1099c1a220e7SZhang Rui } 1100c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1101c1a220e7SZhang Rui 11026d141c3fSLi Zefan static void delayed_work_timer_fn(unsigned long __data) 11031da177e4SLinus Torvalds { 110452bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 11057a22ad75STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); 11061da177e4SLinus Torvalds 11074690c4abSTejun Heo __queue_work(smp_processor_id(), cwq->wq, &dwork->work); 11081da177e4SLinus Torvalds } 11091da177e4SLinus Torvalds 11100fcb78c2SRolf Eike Beer /** 11110fcb78c2SRolf Eike Beer * queue_delayed_work - queue work on a workqueue after delay 11120fcb78c2SRolf Eike Beer * @wq: workqueue to use 1113af9997e4SRandy Dunlap * @dwork: delayable work to queue 11140fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 11150fcb78c2SRolf Eike Beer * 1116057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 11170fcb78c2SRolf Eike Beer */ 11187ad5b3a5SHarvey Harrison int queue_delayed_work(struct workqueue_struct *wq, 111952bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 11201da177e4SLinus Torvalds { 112152bad64dSDavid Howells if (delay == 0) 112263bc0362SOleg Nesterov return queue_work(wq, &dwork->work); 11231da177e4SLinus Torvalds 112463bc0362SOleg Nesterov return queue_delayed_work_on(-1, wq, dwork, delay); 11251da177e4SLinus Torvalds } 1126ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work); 11271da177e4SLinus Torvalds 11280fcb78c2SRolf Eike Beer /** 11290fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 11300fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 11310fcb78c2SRolf Eike Beer * @wq: workqueue to use 1132af9997e4SRandy Dunlap * @dwork: work to queue 11330fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 11340fcb78c2SRolf Eike Beer * 1135057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 11360fcb78c2SRolf Eike Beer */ 11377a6bc1cdSVenkatesh Pallipadi int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 113852bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 11397a6bc1cdSVenkatesh Pallipadi { 11407a6bc1cdSVenkatesh Pallipadi int ret = 0; 114152bad64dSDavid Howells struct timer_list *timer = &dwork->timer; 114252bad64dSDavid Howells struct work_struct *work = &dwork->work; 11437a6bc1cdSVenkatesh Pallipadi 114422df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 1145c7fc77f7STejun Heo unsigned int lcpu; 11467a22ad75STejun Heo 11477a6bc1cdSVenkatesh Pallipadi BUG_ON(timer_pending(timer)); 11487a6bc1cdSVenkatesh Pallipadi BUG_ON(!list_empty(&work->entry)); 11497a6bc1cdSVenkatesh Pallipadi 11508a3e77ccSAndrew Liu timer_stats_timer_set_start_info(&dwork->timer); 11518a3e77ccSAndrew Liu 11527a22ad75STejun Heo /* 11537a22ad75STejun Heo * This stores cwq for the moment, for the timer_fn. 11547a22ad75STejun Heo * Note that the work's gcwq is preserved to allow 11557a22ad75STejun Heo * reentrance detection for delayed works. 11567a22ad75STejun Heo */ 1157c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1158c7fc77f7STejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 1159c7fc77f7STejun Heo 1160c7fc77f7STejun Heo if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) 1161c7fc77f7STejun Heo lcpu = gcwq->cpu; 1162c7fc77f7STejun Heo else 1163c7fc77f7STejun Heo lcpu = raw_smp_processor_id(); 1164c7fc77f7STejun Heo } else 1165c7fc77f7STejun Heo lcpu = WORK_CPU_UNBOUND; 1166c7fc77f7STejun Heo 11677a22ad75STejun Heo set_work_cwq(work, get_cwq(lcpu, wq), 0); 1168c7fc77f7STejun Heo 11697a6bc1cdSVenkatesh Pallipadi timer->expires = jiffies + delay; 117052bad64dSDavid Howells timer->data = (unsigned long)dwork; 11717a6bc1cdSVenkatesh Pallipadi timer->function = delayed_work_timer_fn; 117263bc0362SOleg Nesterov 117363bc0362SOleg Nesterov if (unlikely(cpu >= 0)) 11747a6bc1cdSVenkatesh Pallipadi add_timer_on(timer, cpu); 117563bc0362SOleg Nesterov else 117663bc0362SOleg Nesterov add_timer(timer); 11777a6bc1cdSVenkatesh Pallipadi ret = 1; 11787a6bc1cdSVenkatesh Pallipadi } 11797a6bc1cdSVenkatesh Pallipadi return ret; 11807a6bc1cdSVenkatesh Pallipadi } 1181ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 11821da177e4SLinus Torvalds 1183c8e55f36STejun Heo /** 1184c8e55f36STejun Heo * worker_enter_idle - enter idle state 1185c8e55f36STejun Heo * @worker: worker which is entering idle state 1186c8e55f36STejun Heo * 1187c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1188c8e55f36STejun Heo * necessary. 1189c8e55f36STejun Heo * 1190c8e55f36STejun Heo * LOCKING: 1191c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1192c8e55f36STejun Heo */ 1193c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 11941da177e4SLinus Torvalds { 1195c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1196c8e55f36STejun Heo 1197c8e55f36STejun Heo BUG_ON(worker->flags & WORKER_IDLE); 1198c8e55f36STejun Heo BUG_ON(!list_empty(&worker->entry) && 1199c8e55f36STejun Heo (worker->hentry.next || worker->hentry.pprev)); 1200c8e55f36STejun Heo 1201cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1202cb444766STejun Heo worker->flags |= WORKER_IDLE; 1203c8e55f36STejun Heo gcwq->nr_idle++; 1204e22bee78STejun Heo worker->last_active = jiffies; 1205c8e55f36STejun Heo 1206c8e55f36STejun Heo /* idle_list is LIFO */ 1207c8e55f36STejun Heo list_add(&worker->entry, &gcwq->idle_list); 1208db7bccf4STejun Heo 1209e22bee78STejun Heo if (likely(!(worker->flags & WORKER_ROGUE))) { 1210e22bee78STejun Heo if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) 1211e22bee78STejun Heo mod_timer(&gcwq->idle_timer, 1212e22bee78STejun Heo jiffies + IDLE_WORKER_TIMEOUT); 1213e22bee78STejun Heo } else 1214db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 1215cb444766STejun Heo 1216544ecf31STejun Heo /* 1217544ecf31STejun Heo * Sanity check nr_running. Because trustee releases gcwq->lock 1218544ecf31STejun Heo * between setting %WORKER_ROGUE and zapping nr_running, the 1219544ecf31STejun Heo * warning may trigger spuriously. Check iff trustee is idle. 1220544ecf31STejun Heo */ 1221544ecf31STejun Heo WARN_ON_ONCE(gcwq->trustee_state == TRUSTEE_DONE && 1222544ecf31STejun Heo gcwq->nr_workers == gcwq->nr_idle && 1223cb444766STejun Heo atomic_read(get_gcwq_nr_running(gcwq->cpu))); 1224c8e55f36STejun Heo } 1225c8e55f36STejun Heo 1226c8e55f36STejun Heo /** 1227c8e55f36STejun Heo * worker_leave_idle - leave idle state 1228c8e55f36STejun Heo * @worker: worker which is leaving idle state 1229c8e55f36STejun Heo * 1230c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1231c8e55f36STejun Heo * 1232c8e55f36STejun Heo * LOCKING: 1233c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1234c8e55f36STejun Heo */ 1235c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1236c8e55f36STejun Heo { 1237c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1238c8e55f36STejun Heo 1239c8e55f36STejun Heo BUG_ON(!(worker->flags & WORKER_IDLE)); 1240d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1241c8e55f36STejun Heo gcwq->nr_idle--; 1242c8e55f36STejun Heo list_del_init(&worker->entry); 1243c8e55f36STejun Heo } 1244c8e55f36STejun Heo 1245e22bee78STejun Heo /** 1246e22bee78STejun Heo * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq 1247e22bee78STejun Heo * @worker: self 1248e22bee78STejun Heo * 1249e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1250e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1251e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1252e22bee78STejun Heo * guaranteed to execute on the cpu. 1253e22bee78STejun Heo * 1254e22bee78STejun Heo * This function is to be used by rogue workers and rescuers to bind 1255e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1256e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1257e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1258e22bee78STejun Heo * verbatim as it's best effort and blocking and gcwq may be 1259e22bee78STejun Heo * [dis]associated in the meantime. 1260e22bee78STejun Heo * 1261e22bee78STejun Heo * This function tries set_cpus_allowed() and locks gcwq and verifies 1262e22bee78STejun Heo * the binding against GCWQ_DISASSOCIATED which is set during 1263e22bee78STejun Heo * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters 1264e22bee78STejun Heo * idle state or fetches works without dropping lock, it can guarantee 1265e22bee78STejun Heo * the scheduling requirement described in the first paragraph. 1266e22bee78STejun Heo * 1267e22bee78STejun Heo * CONTEXT: 1268e22bee78STejun Heo * Might sleep. Called without any lock but returns with gcwq->lock 1269e22bee78STejun Heo * held. 1270e22bee78STejun Heo * 1271e22bee78STejun Heo * RETURNS: 1272e22bee78STejun Heo * %true if the associated gcwq is online (@worker is successfully 1273e22bee78STejun Heo * bound), %false if offline. 1274e22bee78STejun Heo */ 1275e22bee78STejun Heo static bool worker_maybe_bind_and_lock(struct worker *worker) 1276972fa1c5SNamhyung Kim __acquires(&gcwq->lock) 1277e22bee78STejun Heo { 1278e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1279e22bee78STejun Heo struct task_struct *task = worker->task; 1280e22bee78STejun Heo 1281e22bee78STejun Heo while (true) { 1282e22bee78STejun Heo /* 1283e22bee78STejun Heo * The following call may fail, succeed or succeed 1284e22bee78STejun Heo * without actually migrating the task to the cpu if 1285e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 1286e22bee78STejun Heo * against GCWQ_DISASSOCIATED. 1287e22bee78STejun Heo */ 1288f3421797STejun Heo if (!(gcwq->flags & GCWQ_DISASSOCIATED)) 1289e22bee78STejun Heo set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); 1290e22bee78STejun Heo 1291e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1292e22bee78STejun Heo if (gcwq->flags & GCWQ_DISASSOCIATED) 1293e22bee78STejun Heo return false; 1294e22bee78STejun Heo if (task_cpu(task) == gcwq->cpu && 1295e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1296e22bee78STejun Heo get_cpu_mask(gcwq->cpu))) 1297e22bee78STejun Heo return true; 1298e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1299e22bee78STejun Heo 13005035b20fSTejun Heo /* 13015035b20fSTejun Heo * We've raced with CPU hot[un]plug. Give it a breather 13025035b20fSTejun Heo * and retry migration. cond_resched() is required here; 13035035b20fSTejun Heo * otherwise, we might deadlock against cpu_stop trying to 13045035b20fSTejun Heo * bring down the CPU on non-preemptive kernel. 13055035b20fSTejun Heo */ 1306e22bee78STejun Heo cpu_relax(); 13075035b20fSTejun Heo cond_resched(); 1308e22bee78STejun Heo } 1309e22bee78STejun Heo } 1310e22bee78STejun Heo 1311e22bee78STejun Heo /* 1312e22bee78STejun Heo * Function for worker->rebind_work used to rebind rogue busy workers 1313e22bee78STejun Heo * to the associated cpu which is coming back online. This is 1314e22bee78STejun Heo * scheduled by cpu up but can race with other cpu hotplug operations 1315e22bee78STejun Heo * and may be executed twice without intervening cpu down. 1316e22bee78STejun Heo */ 1317e22bee78STejun Heo static void worker_rebind_fn(struct work_struct *work) 1318e22bee78STejun Heo { 1319e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1320e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1321e22bee78STejun Heo 1322e22bee78STejun Heo if (worker_maybe_bind_and_lock(worker)) 1323e22bee78STejun Heo worker_clr_flags(worker, WORKER_REBIND); 1324e22bee78STejun Heo 1325e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1326e22bee78STejun Heo } 1327e22bee78STejun Heo 1328c34056a3STejun Heo static struct worker *alloc_worker(void) 1329c34056a3STejun Heo { 1330c34056a3STejun Heo struct worker *worker; 1331c34056a3STejun Heo 1332c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1333c8e55f36STejun Heo if (worker) { 1334c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1335affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1336e22bee78STejun Heo INIT_WORK(&worker->rebind_work, worker_rebind_fn); 1337e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1338e22bee78STejun Heo worker->flags = WORKER_PREP; 1339c8e55f36STejun Heo } 1340c34056a3STejun Heo return worker; 1341c34056a3STejun Heo } 1342c34056a3STejun Heo 1343c34056a3STejun Heo /** 1344c34056a3STejun Heo * create_worker - create a new workqueue worker 13457e11629dSTejun Heo * @gcwq: gcwq the new worker will belong to 1346c34056a3STejun Heo * @bind: whether to set affinity to @cpu or not 1347c34056a3STejun Heo * 13487e11629dSTejun Heo * Create a new worker which is bound to @gcwq. The returned worker 1349c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1350c34056a3STejun Heo * destroy_worker(). 1351c34056a3STejun Heo * 1352c34056a3STejun Heo * CONTEXT: 1353c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1354c34056a3STejun Heo * 1355c34056a3STejun Heo * RETURNS: 1356c34056a3STejun Heo * Pointer to the newly created worker. 1357c34056a3STejun Heo */ 13587e11629dSTejun Heo static struct worker *create_worker(struct global_cwq *gcwq, bool bind) 1359c34056a3STejun Heo { 1360f3421797STejun Heo bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; 1361c34056a3STejun Heo struct worker *worker = NULL; 1362f3421797STejun Heo int id = -1; 1363c34056a3STejun Heo 13648b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13658b03ae3cSTejun Heo while (ida_get_new(&gcwq->worker_ida, &id)) { 13668b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 13678b03ae3cSTejun Heo if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) 1368c34056a3STejun Heo goto fail; 13698b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1370c34056a3STejun Heo } 13718b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1372c34056a3STejun Heo 1373c34056a3STejun Heo worker = alloc_worker(); 1374c34056a3STejun Heo if (!worker) 1375c34056a3STejun Heo goto fail; 1376c34056a3STejun Heo 13778b03ae3cSTejun Heo worker->gcwq = gcwq; 1378c34056a3STejun Heo worker->id = id; 1379c34056a3STejun Heo 1380f3421797STejun Heo if (!on_unbound_cpu) 138194dcf29aSEric Dumazet worker->task = kthread_create_on_node(worker_thread, 138294dcf29aSEric Dumazet worker, 138394dcf29aSEric Dumazet cpu_to_node(gcwq->cpu), 1384f3421797STejun Heo "kworker/%u:%d", gcwq->cpu, id); 1385f3421797STejun Heo else 1386f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1387f3421797STejun Heo "kworker/u:%d", id); 1388c34056a3STejun Heo if (IS_ERR(worker->task)) 1389c34056a3STejun Heo goto fail; 1390c34056a3STejun Heo 1391db7bccf4STejun Heo /* 1392db7bccf4STejun Heo * A rogue worker will become a regular one if CPU comes 1393db7bccf4STejun Heo * online later on. Make sure every worker has 1394db7bccf4STejun Heo * PF_THREAD_BOUND set. 1395db7bccf4STejun Heo */ 1396f3421797STejun Heo if (bind && !on_unbound_cpu) 13978b03ae3cSTejun Heo kthread_bind(worker->task, gcwq->cpu); 1398f3421797STejun Heo else { 1399db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1400f3421797STejun Heo if (on_unbound_cpu) 1401f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1402f3421797STejun Heo } 1403c34056a3STejun Heo 1404c34056a3STejun Heo return worker; 1405c34056a3STejun Heo fail: 1406c34056a3STejun Heo if (id >= 0) { 14078b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 14088b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 14098b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1410c34056a3STejun Heo } 1411c34056a3STejun Heo kfree(worker); 1412c34056a3STejun Heo return NULL; 1413c34056a3STejun Heo } 1414c34056a3STejun Heo 1415c34056a3STejun Heo /** 1416c34056a3STejun Heo * start_worker - start a newly created worker 1417c34056a3STejun Heo * @worker: worker to start 1418c34056a3STejun Heo * 1419c8e55f36STejun Heo * Make the gcwq aware of @worker and start it. 1420c34056a3STejun Heo * 1421c34056a3STejun Heo * CONTEXT: 14228b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1423c34056a3STejun Heo */ 1424c34056a3STejun Heo static void start_worker(struct worker *worker) 1425c34056a3STejun Heo { 1426cb444766STejun Heo worker->flags |= WORKER_STARTED; 1427c8e55f36STejun Heo worker->gcwq->nr_workers++; 1428c8e55f36STejun Heo worker_enter_idle(worker); 1429c34056a3STejun Heo wake_up_process(worker->task); 1430c34056a3STejun Heo } 1431c34056a3STejun Heo 1432c34056a3STejun Heo /** 1433c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1434c34056a3STejun Heo * @worker: worker to be destroyed 1435c34056a3STejun Heo * 1436c8e55f36STejun Heo * Destroy @worker and adjust @gcwq stats accordingly. 1437c8e55f36STejun Heo * 1438c8e55f36STejun Heo * CONTEXT: 1439c8e55f36STejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1440c34056a3STejun Heo */ 1441c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1442c34056a3STejun Heo { 14438b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 1444c34056a3STejun Heo int id = worker->id; 1445c34056a3STejun Heo 1446c34056a3STejun Heo /* sanity check frenzy */ 1447c34056a3STejun Heo BUG_ON(worker->current_work); 1448affee4b2STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1449c34056a3STejun Heo 1450c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1451c8e55f36STejun Heo gcwq->nr_workers--; 1452c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1453c8e55f36STejun Heo gcwq->nr_idle--; 1454c8e55f36STejun Heo 1455c8e55f36STejun Heo list_del_init(&worker->entry); 1456cb444766STejun Heo worker->flags |= WORKER_DIE; 1457c8e55f36STejun Heo 1458c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1459c8e55f36STejun Heo 1460c34056a3STejun Heo kthread_stop(worker->task); 1461c34056a3STejun Heo kfree(worker); 1462c34056a3STejun Heo 14638b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 14648b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 1465c34056a3STejun Heo } 1466c34056a3STejun Heo 1467e22bee78STejun Heo static void idle_worker_timeout(unsigned long __gcwq) 1468e22bee78STejun Heo { 1469e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1470e22bee78STejun Heo 1471e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1472e22bee78STejun Heo 1473e22bee78STejun Heo if (too_many_workers(gcwq)) { 1474e22bee78STejun Heo struct worker *worker; 1475e22bee78STejun Heo unsigned long expires; 1476e22bee78STejun Heo 1477e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 1478e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1479e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1480e22bee78STejun Heo 1481e22bee78STejun Heo if (time_before(jiffies, expires)) 1482e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1483e22bee78STejun Heo else { 1484e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 1485e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 1486e22bee78STejun Heo wake_up_worker(gcwq); 1487e22bee78STejun Heo } 1488e22bee78STejun Heo } 1489e22bee78STejun Heo 1490e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1491e22bee78STejun Heo } 1492e22bee78STejun Heo 1493e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1494e22bee78STejun Heo { 1495e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1496e22bee78STejun Heo struct workqueue_struct *wq = cwq->wq; 1497f3421797STejun Heo unsigned int cpu; 1498e22bee78STejun Heo 1499e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1500e22bee78STejun Heo return false; 1501e22bee78STejun Heo 1502e22bee78STejun Heo /* mayday mayday mayday */ 1503f3421797STejun Heo cpu = cwq->gcwq->cpu; 1504f3421797STejun Heo /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1505f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 1506f3421797STejun Heo cpu = 0; 1507f2e005aaSTejun Heo if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) 1508e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1509e22bee78STejun Heo return true; 1510e22bee78STejun Heo } 1511e22bee78STejun Heo 1512e22bee78STejun Heo static void gcwq_mayday_timeout(unsigned long __gcwq) 1513e22bee78STejun Heo { 1514e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1515e22bee78STejun Heo struct work_struct *work; 1516e22bee78STejun Heo 1517e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1518e22bee78STejun Heo 1519e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 1520e22bee78STejun Heo /* 1521e22bee78STejun Heo * We've been trying to create a new worker but 1522e22bee78STejun Heo * haven't been successful. We might be hitting an 1523e22bee78STejun Heo * allocation deadlock. Send distress signals to 1524e22bee78STejun Heo * rescuers. 1525e22bee78STejun Heo */ 1526e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) 1527e22bee78STejun Heo send_mayday(work); 1528e22bee78STejun Heo } 1529e22bee78STejun Heo 1530e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1531e22bee78STejun Heo 1532e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); 1533e22bee78STejun Heo } 1534e22bee78STejun Heo 1535e22bee78STejun Heo /** 1536e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 1537e22bee78STejun Heo * @gcwq: gcwq to create a new worker for 1538e22bee78STejun Heo * 1539e22bee78STejun Heo * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to 1540e22bee78STejun Heo * have at least one idle worker on return from this function. If 1541e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 1542e22bee78STejun Heo * sent to all rescuers with works scheduled on @gcwq to resolve 1543e22bee78STejun Heo * possible allocation deadlock. 1544e22bee78STejun Heo * 1545e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1546e22bee78STejun Heo * may_start_working() true. 1547e22bee78STejun Heo * 1548e22bee78STejun Heo * LOCKING: 1549e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1550e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1551e22bee78STejun Heo * manager. 1552e22bee78STejun Heo * 1553e22bee78STejun Heo * RETURNS: 1554e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1555e22bee78STejun Heo * otherwise. 1556e22bee78STejun Heo */ 1557e22bee78STejun Heo static bool maybe_create_worker(struct global_cwq *gcwq) 155806bd6ebfSNamhyung Kim __releases(&gcwq->lock) 155906bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 1560e22bee78STejun Heo { 1561e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1562e22bee78STejun Heo return false; 1563e22bee78STejun Heo restart: 15649f9c2364STejun Heo spin_unlock_irq(&gcwq->lock); 15659f9c2364STejun Heo 1566e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 1567e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1568e22bee78STejun Heo 1569e22bee78STejun Heo while (true) { 1570e22bee78STejun Heo struct worker *worker; 1571e22bee78STejun Heo 1572e22bee78STejun Heo worker = create_worker(gcwq, true); 1573e22bee78STejun Heo if (worker) { 1574e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1575e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1576e22bee78STejun Heo start_worker(worker); 1577e22bee78STejun Heo BUG_ON(need_to_create_worker(gcwq)); 1578e22bee78STejun Heo return true; 1579e22bee78STejun Heo } 1580e22bee78STejun Heo 1581e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1582e22bee78STejun Heo break; 1583e22bee78STejun Heo 1584e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1585e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 15869f9c2364STejun Heo 1587e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1588e22bee78STejun Heo break; 1589e22bee78STejun Heo } 1590e22bee78STejun Heo 1591e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1592e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1593e22bee78STejun Heo if (need_to_create_worker(gcwq)) 1594e22bee78STejun Heo goto restart; 1595e22bee78STejun Heo return true; 1596e22bee78STejun Heo } 1597e22bee78STejun Heo 1598e22bee78STejun Heo /** 1599e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 1600e22bee78STejun Heo * @gcwq: gcwq to destroy workers for 1601e22bee78STejun Heo * 1602e22bee78STejun Heo * Destroy @gcwq workers which have been idle for longer than 1603e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1604e22bee78STejun Heo * 1605e22bee78STejun Heo * LOCKING: 1606e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1607e22bee78STejun Heo * multiple times. Called only from manager. 1608e22bee78STejun Heo * 1609e22bee78STejun Heo * RETURNS: 1610e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1611e22bee78STejun Heo * otherwise. 1612e22bee78STejun Heo */ 1613e22bee78STejun Heo static bool maybe_destroy_workers(struct global_cwq *gcwq) 1614e22bee78STejun Heo { 1615e22bee78STejun Heo bool ret = false; 1616e22bee78STejun Heo 1617e22bee78STejun Heo while (too_many_workers(gcwq)) { 1618e22bee78STejun Heo struct worker *worker; 1619e22bee78STejun Heo unsigned long expires; 1620e22bee78STejun Heo 1621e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1622e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1623e22bee78STejun Heo 1624e22bee78STejun Heo if (time_before(jiffies, expires)) { 1625e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1626e22bee78STejun Heo break; 1627e22bee78STejun Heo } 1628e22bee78STejun Heo 1629e22bee78STejun Heo destroy_worker(worker); 1630e22bee78STejun Heo ret = true; 1631e22bee78STejun Heo } 1632e22bee78STejun Heo 1633e22bee78STejun Heo return ret; 1634e22bee78STejun Heo } 1635e22bee78STejun Heo 1636e22bee78STejun Heo /** 1637e22bee78STejun Heo * manage_workers - manage worker pool 1638e22bee78STejun Heo * @worker: self 1639e22bee78STejun Heo * 1640e22bee78STejun Heo * Assume the manager role and manage gcwq worker pool @worker belongs 1641e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 1642e22bee78STejun Heo * gcwq. The exclusion is handled automatically by this function. 1643e22bee78STejun Heo * 1644e22bee78STejun Heo * The caller can safely start processing works on false return. On 1645e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 1646e22bee78STejun Heo * and may_start_working() is true. 1647e22bee78STejun Heo * 1648e22bee78STejun Heo * CONTEXT: 1649e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1650e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 1651e22bee78STejun Heo * 1652e22bee78STejun Heo * RETURNS: 1653e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true if 1654e22bee78STejun Heo * some action was taken. 1655e22bee78STejun Heo */ 1656e22bee78STejun Heo static bool manage_workers(struct worker *worker) 1657e22bee78STejun Heo { 1658e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1659e22bee78STejun Heo bool ret = false; 1660e22bee78STejun Heo 1661e22bee78STejun Heo if (gcwq->flags & GCWQ_MANAGING_WORKERS) 1662e22bee78STejun Heo return ret; 1663e22bee78STejun Heo 1664e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGE_WORKERS; 1665e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 1666e22bee78STejun Heo 1667e22bee78STejun Heo /* 1668e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 1669e22bee78STejun Heo * on return. 1670e22bee78STejun Heo */ 1671e22bee78STejun Heo ret |= maybe_destroy_workers(gcwq); 1672e22bee78STejun Heo ret |= maybe_create_worker(gcwq); 1673e22bee78STejun Heo 1674e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 1675e22bee78STejun Heo 1676e22bee78STejun Heo /* 1677e22bee78STejun Heo * The trustee might be waiting to take over the manager 1678e22bee78STejun Heo * position, tell it we're done. 1679e22bee78STejun Heo */ 1680e22bee78STejun Heo if (unlikely(gcwq->trustee)) 1681e22bee78STejun Heo wake_up_all(&gcwq->trustee_wait); 1682e22bee78STejun Heo 1683e22bee78STejun Heo return ret; 1684e22bee78STejun Heo } 1685e22bee78STejun Heo 1686a62428c0STejun Heo /** 1687affee4b2STejun Heo * move_linked_works - move linked works to a list 1688affee4b2STejun Heo * @work: start of series of works to be scheduled 1689affee4b2STejun Heo * @head: target list to append @work to 1690affee4b2STejun Heo * @nextp: out paramter for nested worklist walking 1691affee4b2STejun Heo * 1692affee4b2STejun Heo * Schedule linked works starting from @work to @head. Work series to 1693affee4b2STejun Heo * be scheduled starts at @work and includes any consecutive work with 1694affee4b2STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 1695affee4b2STejun Heo * 1696affee4b2STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 1697affee4b2STejun Heo * the last scheduled work. This allows move_linked_works() to be 1698affee4b2STejun Heo * nested inside outer list_for_each_entry_safe(). 1699affee4b2STejun Heo * 1700affee4b2STejun Heo * CONTEXT: 17018b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1702affee4b2STejun Heo */ 1703affee4b2STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1704affee4b2STejun Heo struct work_struct **nextp) 1705affee4b2STejun Heo { 1706affee4b2STejun Heo struct work_struct *n; 1707affee4b2STejun Heo 1708affee4b2STejun Heo /* 1709affee4b2STejun Heo * Linked worklist will always end before the end of the list, 1710affee4b2STejun Heo * use NULL for list head. 1711affee4b2STejun Heo */ 1712affee4b2STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1713affee4b2STejun Heo list_move_tail(&work->entry, head); 1714affee4b2STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1715affee4b2STejun Heo break; 1716affee4b2STejun Heo } 1717affee4b2STejun Heo 1718affee4b2STejun Heo /* 1719affee4b2STejun Heo * If we're already inside safe list traversal and have moved 1720affee4b2STejun Heo * multiple works to the scheduled queue, the next position 1721affee4b2STejun Heo * needs to be updated. 1722affee4b2STejun Heo */ 1723affee4b2STejun Heo if (nextp) 1724affee4b2STejun Heo *nextp = n; 1725affee4b2STejun Heo } 1726affee4b2STejun Heo 17271e19ffc6STejun Heo static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) 17281e19ffc6STejun Heo { 17291e19ffc6STejun Heo struct work_struct *work = list_first_entry(&cwq->delayed_works, 17301da177e4SLinus Torvalds struct work_struct, entry); 1731649027d7STejun Heo struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); 17321e19ffc6STejun Heo 1733cdadf009STejun Heo trace_workqueue_activate_work(work); 1734649027d7STejun Heo move_linked_works(work, pos, NULL); 17358a2e8e5dSTejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 17361e19ffc6STejun Heo cwq->nr_active++; 17371e19ffc6STejun Heo } 17381e19ffc6STejun Heo 1739affee4b2STejun Heo /** 174073f53c4aSTejun Heo * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight 174173f53c4aSTejun Heo * @cwq: cwq of interest 174273f53c4aSTejun Heo * @color: color of work which left the queue 17438a2e8e5dSTejun Heo * @delayed: for a delayed work 174473f53c4aSTejun Heo * 174573f53c4aSTejun Heo * A work either has completed or is removed from pending queue, 174673f53c4aSTejun Heo * decrement nr_in_flight of its cwq and handle workqueue flushing. 174773f53c4aSTejun Heo * 174873f53c4aSTejun Heo * CONTEXT: 17498b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 175073f53c4aSTejun Heo */ 17518a2e8e5dSTejun Heo static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, 17528a2e8e5dSTejun Heo bool delayed) 175373f53c4aSTejun Heo { 175473f53c4aSTejun Heo /* ignore uncolored works */ 175573f53c4aSTejun Heo if (color == WORK_NO_COLOR) 175673f53c4aSTejun Heo return; 175773f53c4aSTejun Heo 175873f53c4aSTejun Heo cwq->nr_in_flight[color]--; 17591e19ffc6STejun Heo 17608a2e8e5dSTejun Heo if (!delayed) { 17618a2e8e5dSTejun Heo cwq->nr_active--; 1762502ca9d8STejun Heo if (!list_empty(&cwq->delayed_works)) { 17631e19ffc6STejun Heo /* one down, submit a delayed one */ 1764502ca9d8STejun Heo if (cwq->nr_active < cwq->max_active) 17651e19ffc6STejun Heo cwq_activate_first_delayed(cwq); 1766502ca9d8STejun Heo } 17678a2e8e5dSTejun Heo } 176873f53c4aSTejun Heo 176973f53c4aSTejun Heo /* is flush in progress and are we at the flushing tip? */ 177073f53c4aSTejun Heo if (likely(cwq->flush_color != color)) 177173f53c4aSTejun Heo return; 177273f53c4aSTejun Heo 177373f53c4aSTejun Heo /* are there still in-flight works? */ 177473f53c4aSTejun Heo if (cwq->nr_in_flight[color]) 177573f53c4aSTejun Heo return; 177673f53c4aSTejun Heo 177773f53c4aSTejun Heo /* this cwq is done, clear flush_color */ 177873f53c4aSTejun Heo cwq->flush_color = -1; 177973f53c4aSTejun Heo 178073f53c4aSTejun Heo /* 178173f53c4aSTejun Heo * If this was the last cwq, wake up the first flusher. It 178273f53c4aSTejun Heo * will handle the rest. 178373f53c4aSTejun Heo */ 178473f53c4aSTejun Heo if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) 178573f53c4aSTejun Heo complete(&cwq->wq->first_flusher->done); 178673f53c4aSTejun Heo } 178773f53c4aSTejun Heo 178873f53c4aSTejun Heo /** 1789a62428c0STejun Heo * process_one_work - process single work 1790c34056a3STejun Heo * @worker: self 1791a62428c0STejun Heo * @work: work to process 1792a62428c0STejun Heo * 1793a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 1794a62428c0STejun Heo * process a single work including synchronization against and 1795a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 1796a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 1797a62428c0STejun Heo * call this function to process a work. 1798a62428c0STejun Heo * 1799a62428c0STejun Heo * CONTEXT: 18008b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1801a62428c0STejun Heo */ 1802c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 180306bd6ebfSNamhyung Kim __releases(&gcwq->lock) 180406bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 18051da177e4SLinus Torvalds { 18067e11629dSTejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 18078b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 1808c8e55f36STejun Heo struct hlist_head *bwh = busy_worker_head(gcwq, work); 1809fb0e7bebSTejun Heo bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 18106bb49e59SDavid Howells work_func_t f = work->func; 181173f53c4aSTejun Heo int work_color; 18127e11629dSTejun Heo struct worker *collision; 18134e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 18144e6045f1SJohannes Berg /* 1815a62428c0STejun Heo * It is permissible to free the struct work_struct from 1816a62428c0STejun Heo * inside the function that is called from it, this we need to 1817a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 1818a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 1819a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 18204e6045f1SJohannes Berg */ 18214d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 18224d82a1deSPeter Zijlstra 18234d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 18244e6045f1SJohannes Berg #endif 18257e11629dSTejun Heo /* 18267e11629dSTejun Heo * A single work shouldn't be executed concurrently by 18277e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 18287e11629dSTejun Heo * already processing the work. If so, defer the work to the 18297e11629dSTejun Heo * currently executing one. 18307e11629dSTejun Heo */ 18317e11629dSTejun Heo collision = __find_worker_executing_work(gcwq, bwh, work); 18327e11629dSTejun Heo if (unlikely(collision)) { 18337e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 18347e11629dSTejun Heo return; 18357e11629dSTejun Heo } 18361da177e4SLinus Torvalds 1837a62428c0STejun Heo /* claim and process */ 18381da177e4SLinus Torvalds debug_work_deactivate(work); 1839c8e55f36STejun Heo hlist_add_head(&worker->hentry, bwh); 1840c34056a3STejun Heo worker->current_work = work; 18418cca0eeaSTejun Heo worker->current_cwq = cwq; 184273f53c4aSTejun Heo work_color = get_work_color(work); 18437a22ad75STejun Heo 18447a22ad75STejun Heo /* record the current cpu number in the work data and dequeue */ 18457a22ad75STejun Heo set_work_cpu(work, gcwq->cpu); 1846a62428c0STejun Heo list_del_init(&work->entry); 1847a62428c0STejun Heo 1848649027d7STejun Heo /* 1849649027d7STejun Heo * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, 1850649027d7STejun Heo * wake up another worker; otherwise, clear HIGHPRI_PENDING. 1851649027d7STejun Heo */ 1852649027d7STejun Heo if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { 1853649027d7STejun Heo struct work_struct *nwork = list_first_entry(&gcwq->worklist, 1854649027d7STejun Heo struct work_struct, entry); 1855649027d7STejun Heo 1856649027d7STejun Heo if (!list_empty(&gcwq->worklist) && 1857649027d7STejun Heo get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) 1858649027d7STejun Heo wake_up_worker(gcwq); 1859649027d7STejun Heo else 1860649027d7STejun Heo gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; 1861649027d7STejun Heo } 1862649027d7STejun Heo 1863fb0e7bebSTejun Heo /* 1864fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 1865fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 1866fb0e7bebSTejun Heo */ 1867fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1868fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 1869fb0e7bebSTejun Heo 18708b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 18711da177e4SLinus Torvalds 187223b2e599SOleg Nesterov work_clear_pending(work); 1873e159489bSTejun Heo lock_map_acquire_read(&cwq->wq->lockdep_map); 18743295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 1875e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 187665f27f38SDavid Howells f(work); 1877e36c886aSArjan van de Ven /* 1878e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 1879e36c886aSArjan van de Ven * point will only record its address. 1880e36c886aSArjan van de Ven */ 1881e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 18823295f0efSIngo Molnar lock_map_release(&lockdep_map); 18833295f0efSIngo Molnar lock_map_release(&cwq->wq->lockdep_map); 18841da177e4SLinus Torvalds 1885d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 1886d5abe669SPeter Zijlstra printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " 1887d5abe669SPeter Zijlstra "%s/0x%08x/%d\n", 1888a62428c0STejun Heo current->comm, preempt_count(), task_pid_nr(current)); 1889d5abe669SPeter Zijlstra printk(KERN_ERR " last function: "); 1890d5abe669SPeter Zijlstra print_symbol("%s\n", (unsigned long)f); 1891d5abe669SPeter Zijlstra debug_show_held_locks(current); 1892d5abe669SPeter Zijlstra dump_stack(); 1893d5abe669SPeter Zijlstra } 1894d5abe669SPeter Zijlstra 18958b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1896a62428c0STejun Heo 1897fb0e7bebSTejun Heo /* clear cpu intensive status */ 1898fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1899fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 1900fb0e7bebSTejun Heo 1901a62428c0STejun Heo /* we're done with it, release */ 1902c8e55f36STejun Heo hlist_del_init(&worker->hentry); 1903c34056a3STejun Heo worker->current_work = NULL; 19048cca0eeaSTejun Heo worker->current_cwq = NULL; 19058a2e8e5dSTejun Heo cwq_dec_nr_in_flight(cwq, work_color, false); 19061da177e4SLinus Torvalds } 19071da177e4SLinus Torvalds 1908affee4b2STejun Heo /** 1909affee4b2STejun Heo * process_scheduled_works - process scheduled works 1910affee4b2STejun Heo * @worker: self 1911affee4b2STejun Heo * 1912affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 1913affee4b2STejun Heo * may change while processing a work, so this function repeatedly 1914affee4b2STejun Heo * fetches a work from the top and executes it. 1915affee4b2STejun Heo * 1916affee4b2STejun Heo * CONTEXT: 19178b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1918affee4b2STejun Heo * multiple times. 1919affee4b2STejun Heo */ 1920affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 19211da177e4SLinus Torvalds { 1922affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 1923affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 1924a62428c0STejun Heo struct work_struct, entry); 1925c34056a3STejun Heo process_one_work(worker, work); 1926a62428c0STejun Heo } 19271da177e4SLinus Torvalds } 19281da177e4SLinus Torvalds 19294690c4abSTejun Heo /** 19304690c4abSTejun Heo * worker_thread - the worker thread function 1931c34056a3STejun Heo * @__worker: self 19324690c4abSTejun Heo * 1933e22bee78STejun Heo * The gcwq worker thread function. There's a single dynamic pool of 1934e22bee78STejun Heo * these per each cpu. These workers process all works regardless of 1935e22bee78STejun Heo * their specific target workqueue. The only exception is works which 1936e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 1937e22bee78STejun Heo * rescuer_thread(). 19384690c4abSTejun Heo */ 1939c34056a3STejun Heo static int worker_thread(void *__worker) 19401da177e4SLinus Torvalds { 1941c34056a3STejun Heo struct worker *worker = __worker; 19428b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 19431da177e4SLinus Torvalds 1944e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 1945e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 1946c8e55f36STejun Heo woke_up: 19478b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1948affee4b2STejun Heo 1949c8e55f36STejun Heo /* DIE can be set only while we're idle, checking here is enough */ 1950c8e55f36STejun Heo if (worker->flags & WORKER_DIE) { 1951c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1952e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 1953c8e55f36STejun Heo return 0; 1954c8e55f36STejun Heo } 1955c8e55f36STejun Heo 1956c8e55f36STejun Heo worker_leave_idle(worker); 1957db7bccf4STejun Heo recheck: 1958e22bee78STejun Heo /* no more worker necessary? */ 1959e22bee78STejun Heo if (!need_more_worker(gcwq)) 1960e22bee78STejun Heo goto sleep; 1961e22bee78STejun Heo 1962e22bee78STejun Heo /* do we need to manage? */ 1963e22bee78STejun Heo if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) 1964e22bee78STejun Heo goto recheck; 1965e22bee78STejun Heo 1966c8e55f36STejun Heo /* 1967c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 1968c8e55f36STejun Heo * preparing to process a work or actually processing it. 1969c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 1970c8e55f36STejun Heo */ 1971c8e55f36STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1972c8e55f36STejun Heo 1973e22bee78STejun Heo /* 1974e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 1975e22bee78STejun Heo * at least one idle worker or that someone else has already 1976e22bee78STejun Heo * assumed the manager role. 1977e22bee78STejun Heo */ 1978e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 1979e22bee78STejun Heo 1980e22bee78STejun Heo do { 1981affee4b2STejun Heo struct work_struct *work = 19827e11629dSTejun Heo list_first_entry(&gcwq->worklist, 1983affee4b2STejun Heo struct work_struct, entry); 1984affee4b2STejun Heo 1985c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 1986affee4b2STejun Heo /* optimization path, not strictly necessary */ 1987affee4b2STejun Heo process_one_work(worker, work); 1988affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 1989affee4b2STejun Heo process_scheduled_works(worker); 1990affee4b2STejun Heo } else { 1991c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 1992affee4b2STejun Heo process_scheduled_works(worker); 1993affee4b2STejun Heo } 1994e22bee78STejun Heo } while (keep_working(gcwq)); 1995affee4b2STejun Heo 1996e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 1997d313dd85STejun Heo sleep: 1998e22bee78STejun Heo if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) 1999e22bee78STejun Heo goto recheck; 2000d313dd85STejun Heo 2001c8e55f36STejun Heo /* 2002e22bee78STejun Heo * gcwq->lock is held and there's no work to process and no 2003e22bee78STejun Heo * need to manage, sleep. Workers are woken up only while 2004e22bee78STejun Heo * holding gcwq->lock or from local cpu, so setting the 2005e22bee78STejun Heo * current state before releasing gcwq->lock is enough to 2006e22bee78STejun Heo * prevent losing any event. 2007c8e55f36STejun Heo */ 2008c8e55f36STejun Heo worker_enter_idle(worker); 2009c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 20108b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 20111da177e4SLinus Torvalds schedule(); 2012c8e55f36STejun Heo goto woke_up; 20131da177e4SLinus Torvalds } 20141da177e4SLinus Torvalds 2015e22bee78STejun Heo /** 2016e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2017e22bee78STejun Heo * @__wq: the associated workqueue 2018e22bee78STejun Heo * 2019e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2020e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 2021e22bee78STejun Heo * 2022e22bee78STejun Heo * Regular work processing on a gcwq may block trying to create a new 2023e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2024e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2025e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2026e22bee78STejun Heo * the problem rescuer solves. 2027e22bee78STejun Heo * 2028e22bee78STejun Heo * When such condition is possible, the gcwq summons rescuers of all 2029e22bee78STejun Heo * workqueues which have works queued on the gcwq and let them process 2030e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2031e22bee78STejun Heo * 2032e22bee78STejun Heo * This should happen rarely. 2033e22bee78STejun Heo */ 2034e22bee78STejun Heo static int rescuer_thread(void *__wq) 2035e22bee78STejun Heo { 2036e22bee78STejun Heo struct workqueue_struct *wq = __wq; 2037e22bee78STejun Heo struct worker *rescuer = wq->rescuer; 2038e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 2039f3421797STejun Heo bool is_unbound = wq->flags & WQ_UNBOUND; 2040e22bee78STejun Heo unsigned int cpu; 2041e22bee78STejun Heo 2042e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2043e22bee78STejun Heo repeat: 2044e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 20451da177e4SLinus Torvalds 20461da177e4SLinus Torvalds if (kthread_should_stop()) 2047e22bee78STejun Heo return 0; 20481da177e4SLinus Torvalds 2049f3421797STejun Heo /* 2050f3421797STejun Heo * See whether any cpu is asking for help. Unbounded 2051f3421797STejun Heo * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. 2052f3421797STejun Heo */ 2053f2e005aaSTejun Heo for_each_mayday_cpu(cpu, wq->mayday_mask) { 2054f3421797STejun Heo unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 2055f3421797STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); 2056e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 2057e22bee78STejun Heo struct work_struct *work, *n; 2058e22bee78STejun Heo 2059e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2060f2e005aaSTejun Heo mayday_clear_cpu(cpu, wq->mayday_mask); 2061e22bee78STejun Heo 2062e22bee78STejun Heo /* migrate to the target cpu if possible */ 2063e22bee78STejun Heo rescuer->gcwq = gcwq; 2064e22bee78STejun Heo worker_maybe_bind_and_lock(rescuer); 2065e22bee78STejun Heo 2066e22bee78STejun Heo /* 2067e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2068e22bee78STejun Heo * process'em. 2069e22bee78STejun Heo */ 2070e22bee78STejun Heo BUG_ON(!list_empty(&rescuer->scheduled)); 2071e22bee78STejun Heo list_for_each_entry_safe(work, n, &gcwq->worklist, entry) 2072e22bee78STejun Heo if (get_work_cwq(work) == cwq) 2073e22bee78STejun Heo move_linked_works(work, scheduled, &n); 2074e22bee78STejun Heo 2075e22bee78STejun Heo process_scheduled_works(rescuer); 20767576958aSTejun Heo 20777576958aSTejun Heo /* 20787576958aSTejun Heo * Leave this gcwq. If keep_working() is %true, notify a 20797576958aSTejun Heo * regular worker; otherwise, we end up with 0 concurrency 20807576958aSTejun Heo * and stalling the execution. 20817576958aSTejun Heo */ 20827576958aSTejun Heo if (keep_working(gcwq)) 20837576958aSTejun Heo wake_up_worker(gcwq); 20847576958aSTejun Heo 2085e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 20861da177e4SLinus Torvalds } 20871da177e4SLinus Torvalds 2088e22bee78STejun Heo schedule(); 2089e22bee78STejun Heo goto repeat; 20901da177e4SLinus Torvalds } 20911da177e4SLinus Torvalds 2092fc2e4d70SOleg Nesterov struct wq_barrier { 2093fc2e4d70SOleg Nesterov struct work_struct work; 2094fc2e4d70SOleg Nesterov struct completion done; 2095fc2e4d70SOleg Nesterov }; 2096fc2e4d70SOleg Nesterov 2097fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2098fc2e4d70SOleg Nesterov { 2099fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2100fc2e4d70SOleg Nesterov complete(&barr->done); 2101fc2e4d70SOleg Nesterov } 2102fc2e4d70SOleg Nesterov 21034690c4abSTejun Heo /** 21044690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 21054690c4abSTejun Heo * @cwq: cwq to insert barrier into 21064690c4abSTejun Heo * @barr: wq_barrier to insert 2107affee4b2STejun Heo * @target: target work to attach @barr to 2108affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 21094690c4abSTejun Heo * 2110affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2111affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2112affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2113affee4b2STejun Heo * cpu. 2114affee4b2STejun Heo * 2115affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2116affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2117affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2118affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2119affee4b2STejun Heo * after a work with LINKED flag set. 2120affee4b2STejun Heo * 2121affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2122affee4b2STejun Heo * underneath us, so we can't reliably determine cwq from @target. 21234690c4abSTejun Heo * 21244690c4abSTejun Heo * CONTEXT: 21258b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 21264690c4abSTejun Heo */ 212783c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 2128affee4b2STejun Heo struct wq_barrier *barr, 2129affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2130fc2e4d70SOleg Nesterov { 2131affee4b2STejun Heo struct list_head *head; 2132affee4b2STejun Heo unsigned int linked = 0; 2133affee4b2STejun Heo 2134dc186ad7SThomas Gleixner /* 21358b03ae3cSTejun Heo * debugobject calls are safe here even with gcwq->lock locked 2136dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2137dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2138dc186ad7SThomas Gleixner * might deadlock. 2139dc186ad7SThomas Gleixner */ 2140ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 214122df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2142fc2e4d70SOleg Nesterov init_completion(&barr->done); 214383c22520SOleg Nesterov 2144affee4b2STejun Heo /* 2145affee4b2STejun Heo * If @target is currently being executed, schedule the 2146affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2147affee4b2STejun Heo */ 2148affee4b2STejun Heo if (worker) 2149affee4b2STejun Heo head = worker->scheduled.next; 2150affee4b2STejun Heo else { 2151affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2152affee4b2STejun Heo 2153affee4b2STejun Heo head = target->entry.next; 2154affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2155affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2156affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2157affee4b2STejun Heo } 2158affee4b2STejun Heo 2159dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2160affee4b2STejun Heo insert_work(cwq, &barr->work, head, 2161affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2162fc2e4d70SOleg Nesterov } 2163fc2e4d70SOleg Nesterov 216473f53c4aSTejun Heo /** 216573f53c4aSTejun Heo * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing 216673f53c4aSTejun Heo * @wq: workqueue being flushed 216773f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 216873f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 216973f53c4aSTejun Heo * 217073f53c4aSTejun Heo * Prepare cwqs for workqueue flushing. 217173f53c4aSTejun Heo * 217273f53c4aSTejun Heo * If @flush_color is non-negative, flush_color on all cwqs should be 217373f53c4aSTejun Heo * -1. If no cwq has in-flight commands at the specified color, all 217473f53c4aSTejun Heo * cwq->flush_color's stay at -1 and %false is returned. If any cwq 217573f53c4aSTejun Heo * has in flight commands, its cwq->flush_color is set to 217673f53c4aSTejun Heo * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq 217773f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 217873f53c4aSTejun Heo * 217973f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 218073f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 218173f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 218273f53c4aSTejun Heo * is returned. 218373f53c4aSTejun Heo * 218473f53c4aSTejun Heo * If @work_color is non-negative, all cwqs should have the same 218573f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 218673f53c4aSTejun Heo * advanced to @work_color. 218773f53c4aSTejun Heo * 218873f53c4aSTejun Heo * CONTEXT: 218973f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 219073f53c4aSTejun Heo * 219173f53c4aSTejun Heo * RETURNS: 219273f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 219373f53c4aSTejun Heo * otherwise. 219473f53c4aSTejun Heo */ 219573f53c4aSTejun Heo static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, 219673f53c4aSTejun Heo int flush_color, int work_color) 21971da177e4SLinus Torvalds { 219873f53c4aSTejun Heo bool wait = false; 219973f53c4aSTejun Heo unsigned int cpu; 22001da177e4SLinus Torvalds 220173f53c4aSTejun Heo if (flush_color >= 0) { 220273f53c4aSTejun Heo BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); 220373f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 1); 2204dc186ad7SThomas Gleixner } 220514441960SOleg Nesterov 2206f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 220773f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 22088b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 22091da177e4SLinus Torvalds 22108b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 221173f53c4aSTejun Heo 221273f53c4aSTejun Heo if (flush_color >= 0) { 221373f53c4aSTejun Heo BUG_ON(cwq->flush_color != -1); 221473f53c4aSTejun Heo 221573f53c4aSTejun Heo if (cwq->nr_in_flight[flush_color]) { 221673f53c4aSTejun Heo cwq->flush_color = flush_color; 221773f53c4aSTejun Heo atomic_inc(&wq->nr_cwqs_to_flush); 221873f53c4aSTejun Heo wait = true; 22191da177e4SLinus Torvalds } 222073f53c4aSTejun Heo } 222173f53c4aSTejun Heo 222273f53c4aSTejun Heo if (work_color >= 0) { 222373f53c4aSTejun Heo BUG_ON(work_color != work_next_color(cwq->work_color)); 222473f53c4aSTejun Heo cwq->work_color = work_color; 222573f53c4aSTejun Heo } 222673f53c4aSTejun Heo 22278b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 22281da177e4SLinus Torvalds } 22291da177e4SLinus Torvalds 223073f53c4aSTejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) 223173f53c4aSTejun Heo complete(&wq->first_flusher->done); 223273f53c4aSTejun Heo 223373f53c4aSTejun Heo return wait; 223483c22520SOleg Nesterov } 22351da177e4SLinus Torvalds 22360fcb78c2SRolf Eike Beer /** 22371da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 22380fcb78c2SRolf Eike Beer * @wq: workqueue to flush 22391da177e4SLinus Torvalds * 22401da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 22411da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 22421da177e4SLinus Torvalds * 2243fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2244fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 22451da177e4SLinus Torvalds */ 22467ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 22471da177e4SLinus Torvalds { 224873f53c4aSTejun Heo struct wq_flusher this_flusher = { 224973f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 225073f53c4aSTejun Heo .flush_color = -1, 225173f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 225273f53c4aSTejun Heo }; 225373f53c4aSTejun Heo int next_color; 2254b1f4ec17SOleg Nesterov 22553295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 22563295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 225773f53c4aSTejun Heo 225873f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 225973f53c4aSTejun Heo 226073f53c4aSTejun Heo /* 226173f53c4aSTejun Heo * Start-to-wait phase 226273f53c4aSTejun Heo */ 226373f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 226473f53c4aSTejun Heo 226573f53c4aSTejun Heo if (next_color != wq->flush_color) { 226673f53c4aSTejun Heo /* 226773f53c4aSTejun Heo * Color space is not full. The current work_color 226873f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 226973f53c4aSTejun Heo * by one. 227073f53c4aSTejun Heo */ 227173f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow)); 227273f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 227373f53c4aSTejun Heo wq->work_color = next_color; 227473f53c4aSTejun Heo 227573f53c4aSTejun Heo if (!wq->first_flusher) { 227673f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 227773f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 227873f53c4aSTejun Heo 227973f53c4aSTejun Heo wq->first_flusher = &this_flusher; 228073f53c4aSTejun Heo 228173f53c4aSTejun Heo if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, 228273f53c4aSTejun Heo wq->work_color)) { 228373f53c4aSTejun Heo /* nothing to flush, done */ 228473f53c4aSTejun Heo wq->flush_color = next_color; 228573f53c4aSTejun Heo wq->first_flusher = NULL; 228673f53c4aSTejun Heo goto out_unlock; 228773f53c4aSTejun Heo } 228873f53c4aSTejun Heo } else { 228973f53c4aSTejun Heo /* wait in queue */ 229073f53c4aSTejun Heo BUG_ON(wq->flush_color == this_flusher.flush_color); 229173f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 229273f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 229373f53c4aSTejun Heo } 229473f53c4aSTejun Heo } else { 229573f53c4aSTejun Heo /* 229673f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 229773f53c4aSTejun Heo * The next flush completion will assign us 229873f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 229973f53c4aSTejun Heo */ 230073f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 230173f53c4aSTejun Heo } 230273f53c4aSTejun Heo 230373f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 230473f53c4aSTejun Heo 230573f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 230673f53c4aSTejun Heo 230773f53c4aSTejun Heo /* 230873f53c4aSTejun Heo * Wake-up-and-cascade phase 230973f53c4aSTejun Heo * 231073f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 231173f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 231273f53c4aSTejun Heo */ 231373f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 231473f53c4aSTejun Heo return; 231573f53c4aSTejun Heo 231673f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 231773f53c4aSTejun Heo 23184ce48b37STejun Heo /* we might have raced, check again with mutex held */ 23194ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 23204ce48b37STejun Heo goto out_unlock; 23214ce48b37STejun Heo 232273f53c4aSTejun Heo wq->first_flusher = NULL; 232373f53c4aSTejun Heo 232473f53c4aSTejun Heo BUG_ON(!list_empty(&this_flusher.list)); 232573f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 232673f53c4aSTejun Heo 232773f53c4aSTejun Heo while (true) { 232873f53c4aSTejun Heo struct wq_flusher *next, *tmp; 232973f53c4aSTejun Heo 233073f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 233173f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 233273f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 233373f53c4aSTejun Heo break; 233473f53c4aSTejun Heo list_del_init(&next->list); 233573f53c4aSTejun Heo complete(&next->done); 233673f53c4aSTejun Heo } 233773f53c4aSTejun Heo 233873f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow) && 233973f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 234073f53c4aSTejun Heo 234173f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 234273f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 234373f53c4aSTejun Heo 234473f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 234573f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 234673f53c4aSTejun Heo /* 234773f53c4aSTejun Heo * Assign the same color to all overflowed 234873f53c4aSTejun Heo * flushers, advance work_color and append to 234973f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 235073f53c4aSTejun Heo * phase for these overflowed flushers. 235173f53c4aSTejun Heo */ 235273f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 235373f53c4aSTejun Heo tmp->flush_color = wq->work_color; 235473f53c4aSTejun Heo 235573f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 235673f53c4aSTejun Heo 235773f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 235873f53c4aSTejun Heo &wq->flusher_queue); 235973f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 236073f53c4aSTejun Heo } 236173f53c4aSTejun Heo 236273f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 236373f53c4aSTejun Heo BUG_ON(wq->flush_color != wq->work_color); 236473f53c4aSTejun Heo break; 236573f53c4aSTejun Heo } 236673f53c4aSTejun Heo 236773f53c4aSTejun Heo /* 236873f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 236973f53c4aSTejun Heo * the new first flusher and arm cwqs. 237073f53c4aSTejun Heo */ 237173f53c4aSTejun Heo BUG_ON(wq->flush_color == wq->work_color); 237273f53c4aSTejun Heo BUG_ON(wq->flush_color != next->flush_color); 237373f53c4aSTejun Heo 237473f53c4aSTejun Heo list_del_init(&next->list); 237573f53c4aSTejun Heo wq->first_flusher = next; 237673f53c4aSTejun Heo 237773f53c4aSTejun Heo if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) 237873f53c4aSTejun Heo break; 237973f53c4aSTejun Heo 238073f53c4aSTejun Heo /* 238173f53c4aSTejun Heo * Meh... this color is already done, clear first 238273f53c4aSTejun Heo * flusher and repeat cascading. 238373f53c4aSTejun Heo */ 238473f53c4aSTejun Heo wq->first_flusher = NULL; 238573f53c4aSTejun Heo } 238673f53c4aSTejun Heo 238773f53c4aSTejun Heo out_unlock: 238873f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 23891da177e4SLinus Torvalds } 2390ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 23911da177e4SLinus Torvalds 23929c5a2ba7STejun Heo /** 23939c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 23949c5a2ba7STejun Heo * @wq: workqueue to drain 23959c5a2ba7STejun Heo * 23969c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 23979c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 23989c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 23999c5a2ba7STejun Heo * repeatedly until it becomes empty. The number of flushing is detemined 24009c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 24019c5a2ba7STejun Heo * takes too long. 24029c5a2ba7STejun Heo */ 24039c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 24049c5a2ba7STejun Heo { 24059c5a2ba7STejun Heo unsigned int flush_cnt = 0; 24069c5a2ba7STejun Heo unsigned int cpu; 24079c5a2ba7STejun Heo 24089c5a2ba7STejun Heo /* 24099c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 24109c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 24119c5a2ba7STejun Heo * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. 24129c5a2ba7STejun Heo */ 24139c5a2ba7STejun Heo spin_lock(&workqueue_lock); 24149c5a2ba7STejun Heo if (!wq->nr_drainers++) 24159c5a2ba7STejun Heo wq->flags |= WQ_DRAINING; 24169c5a2ba7STejun Heo spin_unlock(&workqueue_lock); 24179c5a2ba7STejun Heo reflush: 24189c5a2ba7STejun Heo flush_workqueue(wq); 24199c5a2ba7STejun Heo 24209c5a2ba7STejun Heo for_each_cwq_cpu(cpu, wq) { 24219c5a2ba7STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2422fa2563e4SThomas Tuttle bool drained; 24239c5a2ba7STejun Heo 2424fa2563e4SThomas Tuttle spin_lock_irq(&cwq->gcwq->lock); 2425fa2563e4SThomas Tuttle drained = !cwq->nr_active && list_empty(&cwq->delayed_works); 2426fa2563e4SThomas Tuttle spin_unlock_irq(&cwq->gcwq->lock); 2427fa2563e4SThomas Tuttle 2428fa2563e4SThomas Tuttle if (drained) 24299c5a2ba7STejun Heo continue; 24309c5a2ba7STejun Heo 24319c5a2ba7STejun Heo if (++flush_cnt == 10 || 24329c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 24339c5a2ba7STejun Heo pr_warning("workqueue %s: flush on destruction isn't complete after %u tries\n", 24349c5a2ba7STejun Heo wq->name, flush_cnt); 24359c5a2ba7STejun Heo goto reflush; 24369c5a2ba7STejun Heo } 24379c5a2ba7STejun Heo 24389c5a2ba7STejun Heo spin_lock(&workqueue_lock); 24399c5a2ba7STejun Heo if (!--wq->nr_drainers) 24409c5a2ba7STejun Heo wq->flags &= ~WQ_DRAINING; 24419c5a2ba7STejun Heo spin_unlock(&workqueue_lock); 24429c5a2ba7STejun Heo } 24439c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 24449c5a2ba7STejun Heo 2445baf59022STejun Heo static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, 2446baf59022STejun Heo bool wait_executing) 2447baf59022STejun Heo { 2448baf59022STejun Heo struct worker *worker = NULL; 2449baf59022STejun Heo struct global_cwq *gcwq; 2450baf59022STejun Heo struct cpu_workqueue_struct *cwq; 2451baf59022STejun Heo 2452baf59022STejun Heo might_sleep(); 2453baf59022STejun Heo gcwq = get_work_gcwq(work); 2454baf59022STejun Heo if (!gcwq) 2455baf59022STejun Heo return false; 2456baf59022STejun Heo 2457baf59022STejun Heo spin_lock_irq(&gcwq->lock); 2458baf59022STejun Heo if (!list_empty(&work->entry)) { 2459baf59022STejun Heo /* 2460baf59022STejun Heo * See the comment near try_to_grab_pending()->smp_rmb(). 2461baf59022STejun Heo * If it was re-queued to a different gcwq under us, we 2462baf59022STejun Heo * are not going to wait. 2463baf59022STejun Heo */ 2464baf59022STejun Heo smp_rmb(); 2465baf59022STejun Heo cwq = get_work_cwq(work); 2466baf59022STejun Heo if (unlikely(!cwq || gcwq != cwq->gcwq)) 2467baf59022STejun Heo goto already_gone; 2468baf59022STejun Heo } else if (wait_executing) { 2469baf59022STejun Heo worker = find_worker_executing_work(gcwq, work); 2470baf59022STejun Heo if (!worker) 2471baf59022STejun Heo goto already_gone; 2472baf59022STejun Heo cwq = worker->current_cwq; 2473baf59022STejun Heo } else 2474baf59022STejun Heo goto already_gone; 2475baf59022STejun Heo 2476baf59022STejun Heo insert_wq_barrier(cwq, barr, work, worker); 2477baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2478baf59022STejun Heo 2479e159489bSTejun Heo /* 2480e159489bSTejun Heo * If @max_active is 1 or rescuer is in use, flushing another work 2481e159489bSTejun Heo * item on the same workqueue may lead to deadlock. Make sure the 2482e159489bSTejun Heo * flusher is not running on the same workqueue by verifying write 2483e159489bSTejun Heo * access. 2484e159489bSTejun Heo */ 2485e159489bSTejun Heo if (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER) 2486baf59022STejun Heo lock_map_acquire(&cwq->wq->lockdep_map); 2487e159489bSTejun Heo else 2488e159489bSTejun Heo lock_map_acquire_read(&cwq->wq->lockdep_map); 2489baf59022STejun Heo lock_map_release(&cwq->wq->lockdep_map); 2490e159489bSTejun Heo 2491baf59022STejun Heo return true; 2492baf59022STejun Heo already_gone: 2493baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2494baf59022STejun Heo return false; 2495baf59022STejun Heo } 2496baf59022STejun Heo 2497db700897SOleg Nesterov /** 2498401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 2499401a8d04STejun Heo * @work: the work to flush 2500db700897SOleg Nesterov * 2501401a8d04STejun Heo * Wait until @work has finished execution. This function considers 2502401a8d04STejun Heo * only the last queueing instance of @work. If @work has been 2503401a8d04STejun Heo * enqueued across different CPUs on a non-reentrant workqueue or on 2504401a8d04STejun Heo * multiple workqueues, @work might still be executing on return on 2505401a8d04STejun Heo * some of the CPUs from earlier queueing. 2506a67da70dSOleg Nesterov * 2507401a8d04STejun Heo * If @work was queued only on a non-reentrant, ordered or unbound 2508401a8d04STejun Heo * workqueue, @work is guaranteed to be idle on return if it hasn't 2509401a8d04STejun Heo * been requeued since flush started. 2510401a8d04STejun Heo * 2511401a8d04STejun Heo * RETURNS: 2512401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2513401a8d04STejun Heo * %false if it was already idle. 2514db700897SOleg Nesterov */ 2515401a8d04STejun Heo bool flush_work(struct work_struct *work) 2516db700897SOleg Nesterov { 2517db700897SOleg Nesterov struct wq_barrier barr; 2518db700897SOleg Nesterov 25190976dfc1SStephen Boyd lock_map_acquire(&work->lockdep_map); 25200976dfc1SStephen Boyd lock_map_release(&work->lockdep_map); 25210976dfc1SStephen Boyd 2522baf59022STejun Heo if (start_flush_work(work, &barr, true)) { 2523db700897SOleg Nesterov wait_for_completion(&barr.done); 2524dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2525401a8d04STejun Heo return true; 2526baf59022STejun Heo } else 2527401a8d04STejun Heo return false; 2528db700897SOleg Nesterov } 2529db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2530db700897SOleg Nesterov 2531401a8d04STejun Heo static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) 2532401a8d04STejun Heo { 2533401a8d04STejun Heo struct wq_barrier barr; 2534401a8d04STejun Heo struct worker *worker; 2535401a8d04STejun Heo 2536401a8d04STejun Heo spin_lock_irq(&gcwq->lock); 2537401a8d04STejun Heo 2538401a8d04STejun Heo worker = find_worker_executing_work(gcwq, work); 2539401a8d04STejun Heo if (unlikely(worker)) 2540401a8d04STejun Heo insert_wq_barrier(worker->current_cwq, &barr, work, worker); 2541401a8d04STejun Heo 2542401a8d04STejun Heo spin_unlock_irq(&gcwq->lock); 2543401a8d04STejun Heo 2544401a8d04STejun Heo if (unlikely(worker)) { 2545401a8d04STejun Heo wait_for_completion(&barr.done); 2546401a8d04STejun Heo destroy_work_on_stack(&barr.work); 2547401a8d04STejun Heo return true; 2548401a8d04STejun Heo } else 2549401a8d04STejun Heo return false; 2550401a8d04STejun Heo } 2551401a8d04STejun Heo 2552401a8d04STejun Heo static bool wait_on_work(struct work_struct *work) 2553401a8d04STejun Heo { 2554401a8d04STejun Heo bool ret = false; 2555401a8d04STejun Heo int cpu; 2556401a8d04STejun Heo 2557401a8d04STejun Heo might_sleep(); 2558401a8d04STejun Heo 2559401a8d04STejun Heo lock_map_acquire(&work->lockdep_map); 2560401a8d04STejun Heo lock_map_release(&work->lockdep_map); 2561401a8d04STejun Heo 2562401a8d04STejun Heo for_each_gcwq_cpu(cpu) 2563401a8d04STejun Heo ret |= wait_on_cpu_work(get_gcwq(cpu), work); 2564401a8d04STejun Heo return ret; 2565401a8d04STejun Heo } 2566401a8d04STejun Heo 256709383498STejun Heo /** 256809383498STejun Heo * flush_work_sync - wait until a work has finished execution 256909383498STejun Heo * @work: the work to flush 257009383498STejun Heo * 257109383498STejun Heo * Wait until @work has finished execution. On return, it's 257209383498STejun Heo * guaranteed that all queueing instances of @work which happened 257309383498STejun Heo * before this function is called are finished. In other words, if 257409383498STejun Heo * @work hasn't been requeued since this function was called, @work is 257509383498STejun Heo * guaranteed to be idle on return. 257609383498STejun Heo * 257709383498STejun Heo * RETURNS: 257809383498STejun Heo * %true if flush_work_sync() waited for the work to finish execution, 257909383498STejun Heo * %false if it was already idle. 258009383498STejun Heo */ 258109383498STejun Heo bool flush_work_sync(struct work_struct *work) 258209383498STejun Heo { 258309383498STejun Heo struct wq_barrier barr; 258409383498STejun Heo bool pending, waited; 258509383498STejun Heo 258609383498STejun Heo /* we'll wait for executions separately, queue barr only if pending */ 258709383498STejun Heo pending = start_flush_work(work, &barr, false); 258809383498STejun Heo 258909383498STejun Heo /* wait for executions to finish */ 259009383498STejun Heo waited = wait_on_work(work); 259109383498STejun Heo 259209383498STejun Heo /* wait for the pending one */ 259309383498STejun Heo if (pending) { 259409383498STejun Heo wait_for_completion(&barr.done); 259509383498STejun Heo destroy_work_on_stack(&barr.work); 259609383498STejun Heo } 259709383498STejun Heo 259809383498STejun Heo return pending || waited; 259909383498STejun Heo } 260009383498STejun Heo EXPORT_SYMBOL_GPL(flush_work_sync); 260109383498STejun Heo 26026e84d644SOleg Nesterov /* 26031f1f642eSOleg Nesterov * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, 26046e84d644SOleg Nesterov * so this work can't be re-armed in any way. 26056e84d644SOleg Nesterov */ 26066e84d644SOleg Nesterov static int try_to_grab_pending(struct work_struct *work) 26076e84d644SOleg Nesterov { 26088b03ae3cSTejun Heo struct global_cwq *gcwq; 26091f1f642eSOleg Nesterov int ret = -1; 26106e84d644SOleg Nesterov 261122df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 26121f1f642eSOleg Nesterov return 0; 26136e84d644SOleg Nesterov 26146e84d644SOleg Nesterov /* 26156e84d644SOleg Nesterov * The queueing is in progress, or it is already queued. Try to 26166e84d644SOleg Nesterov * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 26176e84d644SOleg Nesterov */ 26187a22ad75STejun Heo gcwq = get_work_gcwq(work); 26197a22ad75STejun Heo if (!gcwq) 26206e84d644SOleg Nesterov return ret; 26216e84d644SOleg Nesterov 26228b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 26236e84d644SOleg Nesterov if (!list_empty(&work->entry)) { 26246e84d644SOleg Nesterov /* 26257a22ad75STejun Heo * This work is queued, but perhaps we locked the wrong gcwq. 26266e84d644SOleg Nesterov * In that case we must see the new value after rmb(), see 26276e84d644SOleg Nesterov * insert_work()->wmb(). 26286e84d644SOleg Nesterov */ 26296e84d644SOleg Nesterov smp_rmb(); 26307a22ad75STejun Heo if (gcwq == get_work_gcwq(work)) { 2631dc186ad7SThomas Gleixner debug_work_deactivate(work); 26326e84d644SOleg Nesterov list_del_init(&work->entry); 26337a22ad75STejun Heo cwq_dec_nr_in_flight(get_work_cwq(work), 26348a2e8e5dSTejun Heo get_work_color(work), 26358a2e8e5dSTejun Heo *work_data_bits(work) & WORK_STRUCT_DELAYED); 26366e84d644SOleg Nesterov ret = 1; 26376e84d644SOleg Nesterov } 26386e84d644SOleg Nesterov } 26398b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 26406e84d644SOleg Nesterov 26416e84d644SOleg Nesterov return ret; 26426e84d644SOleg Nesterov } 26436e84d644SOleg Nesterov 2644401a8d04STejun Heo static bool __cancel_work_timer(struct work_struct *work, 26451f1f642eSOleg Nesterov struct timer_list* timer) 26461f1f642eSOleg Nesterov { 26471f1f642eSOleg Nesterov int ret; 26481f1f642eSOleg Nesterov 26491f1f642eSOleg Nesterov do { 26501f1f642eSOleg Nesterov ret = (timer && likely(del_timer(timer))); 26511f1f642eSOleg Nesterov if (!ret) 26521f1f642eSOleg Nesterov ret = try_to_grab_pending(work); 26531f1f642eSOleg Nesterov wait_on_work(work); 26541f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 26551f1f642eSOleg Nesterov 26567a22ad75STejun Heo clear_work_data(work); 26571f1f642eSOleg Nesterov return ret; 26581f1f642eSOleg Nesterov } 26591f1f642eSOleg Nesterov 26606e84d644SOleg Nesterov /** 2661401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 2662401a8d04STejun Heo * @work: the work to cancel 26636e84d644SOleg Nesterov * 2664401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 2665401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 2666401a8d04STejun Heo * another workqueue. On return from this function, @work is 2667401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 26681f1f642eSOleg Nesterov * 2669401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 2670401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 26716e84d644SOleg Nesterov * 2672401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 26736e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 2674401a8d04STejun Heo * 2675401a8d04STejun Heo * RETURNS: 2676401a8d04STejun Heo * %true if @work was pending, %false otherwise. 26776e84d644SOleg Nesterov */ 2678401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 26796e84d644SOleg Nesterov { 26801f1f642eSOleg Nesterov return __cancel_work_timer(work, NULL); 2681b89deed3SOleg Nesterov } 268228e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2683b89deed3SOleg Nesterov 26846e84d644SOleg Nesterov /** 2685401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 2686401a8d04STejun Heo * @dwork: the delayed work to flush 26876e84d644SOleg Nesterov * 2688401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 2689401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 2690401a8d04STejun Heo * considers the last queueing instance of @dwork. 26911f1f642eSOleg Nesterov * 2692401a8d04STejun Heo * RETURNS: 2693401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2694401a8d04STejun Heo * %false if it was already idle. 26956e84d644SOleg Nesterov */ 2696401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 2697401a8d04STejun Heo { 2698401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 2699401a8d04STejun Heo __queue_work(raw_smp_processor_id(), 2700401a8d04STejun Heo get_work_cwq(&dwork->work)->wq, &dwork->work); 2701401a8d04STejun Heo return flush_work(&dwork->work); 2702401a8d04STejun Heo } 2703401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 2704401a8d04STejun Heo 2705401a8d04STejun Heo /** 270609383498STejun Heo * flush_delayed_work_sync - wait for a dwork to finish 270709383498STejun Heo * @dwork: the delayed work to flush 270809383498STejun Heo * 270909383498STejun Heo * Delayed timer is cancelled and the pending work is queued for 271009383498STejun Heo * execution immediately. Other than timer handling, its behavior 271109383498STejun Heo * is identical to flush_work_sync(). 271209383498STejun Heo * 271309383498STejun Heo * RETURNS: 271409383498STejun Heo * %true if flush_work_sync() waited for the work to finish execution, 271509383498STejun Heo * %false if it was already idle. 271609383498STejun Heo */ 271709383498STejun Heo bool flush_delayed_work_sync(struct delayed_work *dwork) 271809383498STejun Heo { 271909383498STejun Heo if (del_timer_sync(&dwork->timer)) 272009383498STejun Heo __queue_work(raw_smp_processor_id(), 272109383498STejun Heo get_work_cwq(&dwork->work)->wq, &dwork->work); 272209383498STejun Heo return flush_work_sync(&dwork->work); 272309383498STejun Heo } 272409383498STejun Heo EXPORT_SYMBOL(flush_delayed_work_sync); 272509383498STejun Heo 272609383498STejun Heo /** 2727401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 2728401a8d04STejun Heo * @dwork: the delayed work cancel 2729401a8d04STejun Heo * 2730401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 2731401a8d04STejun Heo * 2732401a8d04STejun Heo * RETURNS: 2733401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 2734401a8d04STejun Heo */ 2735401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 27366e84d644SOleg Nesterov { 27371f1f642eSOleg Nesterov return __cancel_work_timer(&dwork->work, &dwork->timer); 27386e84d644SOleg Nesterov } 2739f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 27401da177e4SLinus Torvalds 27410fcb78c2SRolf Eike Beer /** 27420fcb78c2SRolf Eike Beer * schedule_work - put work task in global workqueue 27430fcb78c2SRolf Eike Beer * @work: job to be done 27440fcb78c2SRolf Eike Beer * 27455b0f437dSBart Van Assche * Returns zero if @work was already on the kernel-global workqueue and 27465b0f437dSBart Van Assche * non-zero otherwise. 27475b0f437dSBart Van Assche * 27485b0f437dSBart Van Assche * This puts a job in the kernel-global workqueue if it was not already 27495b0f437dSBart Van Assche * queued and leaves it in the same position on the kernel-global 27505b0f437dSBart Van Assche * workqueue otherwise. 27510fcb78c2SRolf Eike Beer */ 27527ad5b3a5SHarvey Harrison int schedule_work(struct work_struct *work) 27531da177e4SLinus Torvalds { 2754d320c038STejun Heo return queue_work(system_wq, work); 27551da177e4SLinus Torvalds } 2756ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_work); 27571da177e4SLinus Torvalds 2758c1a220e7SZhang Rui /* 2759c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2760c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2761c1a220e7SZhang Rui * @work: job to be done 2762c1a220e7SZhang Rui * 2763c1a220e7SZhang Rui * This puts a job on a specific cpu 2764c1a220e7SZhang Rui */ 2765c1a220e7SZhang Rui int schedule_work_on(int cpu, struct work_struct *work) 2766c1a220e7SZhang Rui { 2767d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 2768c1a220e7SZhang Rui } 2769c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 2770c1a220e7SZhang Rui 27710fcb78c2SRolf Eike Beer /** 27720fcb78c2SRolf Eike Beer * schedule_delayed_work - put work task in global workqueue after delay 277352bad64dSDavid Howells * @dwork: job to be done 277452bad64dSDavid Howells * @delay: number of jiffies to wait or 0 for immediate execution 27750fcb78c2SRolf Eike Beer * 27760fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 27770fcb78c2SRolf Eike Beer * workqueue. 27780fcb78c2SRolf Eike Beer */ 27797ad5b3a5SHarvey Harrison int schedule_delayed_work(struct delayed_work *dwork, 278082f67cd9SIngo Molnar unsigned long delay) 27811da177e4SLinus Torvalds { 2782d320c038STejun Heo return queue_delayed_work(system_wq, dwork, delay); 27831da177e4SLinus Torvalds } 2784ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work); 27851da177e4SLinus Torvalds 27860fcb78c2SRolf Eike Beer /** 27870fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 27880fcb78c2SRolf Eike Beer * @cpu: cpu to use 278952bad64dSDavid Howells * @dwork: job to be done 27900fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 27910fcb78c2SRolf Eike Beer * 27920fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 27930fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 27940fcb78c2SRolf Eike Beer */ 27951da177e4SLinus Torvalds int schedule_delayed_work_on(int cpu, 279652bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 27971da177e4SLinus Torvalds { 2798d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 27991da177e4SLinus Torvalds } 2800ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 28011da177e4SLinus Torvalds 2802b6136773SAndrew Morton /** 280331ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 2804b6136773SAndrew Morton * @func: the function to call 2805b6136773SAndrew Morton * 280631ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 280731ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 2808b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 280931ddd871STejun Heo * 281031ddd871STejun Heo * RETURNS: 281131ddd871STejun Heo * 0 on success, -errno on failure. 2812b6136773SAndrew Morton */ 281365f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 281415316ba8SChristoph Lameter { 281515316ba8SChristoph Lameter int cpu; 281638f51568SNamhyung Kim struct work_struct __percpu *works; 281715316ba8SChristoph Lameter 2818b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 2819b6136773SAndrew Morton if (!works) 282015316ba8SChristoph Lameter return -ENOMEM; 2821b6136773SAndrew Morton 282295402b38SGautham R Shenoy get_online_cpus(); 282393981800STejun Heo 282415316ba8SChristoph Lameter for_each_online_cpu(cpu) { 28259bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 28269bfb1839SIngo Molnar 28279bfb1839SIngo Molnar INIT_WORK(work, func); 28288de6d308SOleg Nesterov schedule_work_on(cpu, work); 282915316ba8SChristoph Lameter } 283093981800STejun Heo 283193981800STejun Heo for_each_online_cpu(cpu) 28328616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 283393981800STejun Heo 283495402b38SGautham R Shenoy put_online_cpus(); 2835b6136773SAndrew Morton free_percpu(works); 283615316ba8SChristoph Lameter return 0; 283715316ba8SChristoph Lameter } 283815316ba8SChristoph Lameter 2839eef6a7d5SAlan Stern /** 2840eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 2841eef6a7d5SAlan Stern * 2842eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 2843eef6a7d5SAlan Stern * completion. 2844eef6a7d5SAlan Stern * 2845eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 2846eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 2847eef6a7d5SAlan Stern * will lead to deadlock: 2848eef6a7d5SAlan Stern * 2849eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 2850eef6a7d5SAlan Stern * a lock held by your code or its caller. 2851eef6a7d5SAlan Stern * 2852eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 2853eef6a7d5SAlan Stern * 2854eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 2855eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 2856eef6a7d5SAlan Stern * what locks they need, which you have no control over. 2857eef6a7d5SAlan Stern * 2858eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 2859eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 2860eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 2861eef6a7d5SAlan Stern * cancel_work_sync() instead. 2862eef6a7d5SAlan Stern */ 28631da177e4SLinus Torvalds void flush_scheduled_work(void) 28641da177e4SLinus Torvalds { 2865d320c038STejun Heo flush_workqueue(system_wq); 28661da177e4SLinus Torvalds } 2867ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 28681da177e4SLinus Torvalds 28691da177e4SLinus Torvalds /** 28701fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 28711fa44ecaSJames Bottomley * @fn: the function to execute 28721fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 28731fa44ecaSJames Bottomley * be available when the work executes) 28741fa44ecaSJames Bottomley * 28751fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 28761fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 28771fa44ecaSJames Bottomley * 28781fa44ecaSJames Bottomley * Returns: 0 - function was executed 28791fa44ecaSJames Bottomley * 1 - function was scheduled for execution 28801fa44ecaSJames Bottomley */ 288165f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 28821fa44ecaSJames Bottomley { 28831fa44ecaSJames Bottomley if (!in_interrupt()) { 288465f27f38SDavid Howells fn(&ew->work); 28851fa44ecaSJames Bottomley return 0; 28861fa44ecaSJames Bottomley } 28871fa44ecaSJames Bottomley 288865f27f38SDavid Howells INIT_WORK(&ew->work, fn); 28891fa44ecaSJames Bottomley schedule_work(&ew->work); 28901fa44ecaSJames Bottomley 28911fa44ecaSJames Bottomley return 1; 28921fa44ecaSJames Bottomley } 28931fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 28941fa44ecaSJames Bottomley 28951da177e4SLinus Torvalds int keventd_up(void) 28961da177e4SLinus Torvalds { 2897d320c038STejun Heo return system_wq != NULL; 28981da177e4SLinus Torvalds } 28991da177e4SLinus Torvalds 2900bdbc5dd7STejun Heo static int alloc_cwqs(struct workqueue_struct *wq) 29011da177e4SLinus Torvalds { 29023af24433SOleg Nesterov /* 29030f900049STejun Heo * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. 29040f900049STejun Heo * Make sure that the alignment isn't lower than that of 29050f900049STejun Heo * unsigned long long. 29063af24433SOleg Nesterov */ 29070f900049STejun Heo const size_t size = sizeof(struct cpu_workqueue_struct); 29080f900049STejun Heo const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, 29090f900049STejun Heo __alignof__(unsigned long long)); 29103af24433SOleg Nesterov 2911e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 2912f3421797STejun Heo wq->cpu_wq.pcpu = __alloc_percpu(size, align); 2913931ac77eSTejun Heo else { 29140f900049STejun Heo void *ptr; 2915e1d8aa9fSFrederic Weisbecker 29160f900049STejun Heo /* 2917f3421797STejun Heo * Allocate enough room to align cwq and put an extra 2918f3421797STejun Heo * pointer at the end pointing back to the originally 2919f3421797STejun Heo * allocated pointer which will be used for free. 29200f900049STejun Heo */ 2921bdbc5dd7STejun Heo ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); 2922bdbc5dd7STejun Heo if (ptr) { 2923bdbc5dd7STejun Heo wq->cpu_wq.single = PTR_ALIGN(ptr, align); 2924bdbc5dd7STejun Heo *(void **)(wq->cpu_wq.single + 1) = ptr; 2925bdbc5dd7STejun Heo } 29263af24433SOleg Nesterov } 29273af24433SOleg Nesterov 29280415b00dSTejun Heo /* just in case, make sure it's actually aligned */ 2929bdbc5dd7STejun Heo BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); 2930bdbc5dd7STejun Heo return wq->cpu_wq.v ? 0 : -ENOMEM; 29310f900049STejun Heo } 29320f900049STejun Heo 2933bdbc5dd7STejun Heo static void free_cwqs(struct workqueue_struct *wq) 293406ba38a9SOleg Nesterov { 2935e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 2936bdbc5dd7STejun Heo free_percpu(wq->cpu_wq.pcpu); 2937f3421797STejun Heo else if (wq->cpu_wq.single) { 2938f3421797STejun Heo /* the pointer to free is stored right after the cwq */ 2939f3421797STejun Heo kfree(*(void **)(wq->cpu_wq.single + 1)); 294006ba38a9SOleg Nesterov } 294106ba38a9SOleg Nesterov } 294206ba38a9SOleg Nesterov 2943f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 2944f3421797STejun Heo const char *name) 2945b71ab8c2STejun Heo { 2946f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 2947f3421797STejun Heo 2948f3421797STejun Heo if (max_active < 1 || max_active > lim) 2949b71ab8c2STejun Heo printk(KERN_WARNING "workqueue: max_active %d requested for %s " 2950b71ab8c2STejun Heo "is out of range, clamping between %d and %d\n", 2951f3421797STejun Heo max_active, name, 1, lim); 2952b71ab8c2STejun Heo 2953f3421797STejun Heo return clamp_val(max_active, 1, lim); 2954b71ab8c2STejun Heo } 2955b71ab8c2STejun Heo 2956b196be89STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *fmt, 295797e37d7bSTejun Heo unsigned int flags, 29581e19ffc6STejun Heo int max_active, 2959eb13ba87SJohannes Berg struct lock_class_key *key, 2960b196be89STejun Heo const char *lock_name, ...) 29613af24433SOleg Nesterov { 2962b196be89STejun Heo va_list args, args1; 29633af24433SOleg Nesterov struct workqueue_struct *wq; 2964c34056a3STejun Heo unsigned int cpu; 2965b196be89STejun Heo size_t namelen; 2966b196be89STejun Heo 2967b196be89STejun Heo /* determine namelen, allocate wq and format name */ 2968b196be89STejun Heo va_start(args, lock_name); 2969b196be89STejun Heo va_copy(args1, args); 2970b196be89STejun Heo namelen = vsnprintf(NULL, 0, fmt, args) + 1; 2971b196be89STejun Heo 2972b196be89STejun Heo wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL); 2973b196be89STejun Heo if (!wq) 2974b196be89STejun Heo goto err; 2975b196be89STejun Heo 2976b196be89STejun Heo vsnprintf(wq->name, namelen, fmt, args1); 2977b196be89STejun Heo va_end(args); 2978b196be89STejun Heo va_end(args1); 29793af24433SOleg Nesterov 2980f3421797STejun Heo /* 29816370a6adSTejun Heo * Workqueues which may be used during memory reclaim should 29826370a6adSTejun Heo * have a rescuer to guarantee forward progress. 29836370a6adSTejun Heo */ 29846370a6adSTejun Heo if (flags & WQ_MEM_RECLAIM) 29856370a6adSTejun Heo flags |= WQ_RESCUER; 29866370a6adSTejun Heo 29876370a6adSTejun Heo /* 2988f3421797STejun Heo * Unbound workqueues aren't concurrency managed and should be 2989f3421797STejun Heo * dispatched to workers immediately. 2990f3421797STejun Heo */ 2991f3421797STejun Heo if (flags & WQ_UNBOUND) 2992f3421797STejun Heo flags |= WQ_HIGHPRI; 2993f3421797STejun Heo 2994d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 2995b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 29963af24433SOleg Nesterov 2997b196be89STejun Heo /* init wq */ 299897e37d7bSTejun Heo wq->flags = flags; 2999a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 300073f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 300173f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 0); 300273f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 300373f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 30043af24433SOleg Nesterov 3005eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 3006cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 30073af24433SOleg Nesterov 3008bdbc5dd7STejun Heo if (alloc_cwqs(wq) < 0) 3009bdbc5dd7STejun Heo goto err; 3010bdbc5dd7STejun Heo 3011f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 30121537663fSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 30138b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 30141537663fSTejun Heo 30150f900049STejun Heo BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 30168b03ae3cSTejun Heo cwq->gcwq = gcwq; 3017c34056a3STejun Heo cwq->wq = wq; 301873f53c4aSTejun Heo cwq->flush_color = -1; 30191e19ffc6STejun Heo cwq->max_active = max_active; 30201e19ffc6STejun Heo INIT_LIST_HEAD(&cwq->delayed_works); 3021e22bee78STejun Heo } 30221537663fSTejun Heo 3023e22bee78STejun Heo if (flags & WQ_RESCUER) { 3024e22bee78STejun Heo struct worker *rescuer; 3025e22bee78STejun Heo 3026f2e005aaSTejun Heo if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) 3027e22bee78STejun Heo goto err; 3028e22bee78STejun Heo 3029e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 3030e22bee78STejun Heo if (!rescuer) 3031e22bee78STejun Heo goto err; 3032e22bee78STejun Heo 3033b196be89STejun Heo rescuer->task = kthread_create(rescuer_thread, wq, "%s", 3034b196be89STejun Heo wq->name); 3035e22bee78STejun Heo if (IS_ERR(rescuer->task)) 3036e22bee78STejun Heo goto err; 3037e22bee78STejun Heo 3038e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 3039e22bee78STejun Heo wake_up_process(rescuer->task); 30403af24433SOleg Nesterov } 30411537663fSTejun Heo 30423af24433SOleg Nesterov /* 3043a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 3044a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 3045a0a1a5fdSTejun Heo * workqueue to workqueues list. 30463af24433SOleg Nesterov */ 30473af24433SOleg Nesterov spin_lock(&workqueue_lock); 3048a0a1a5fdSTejun Heo 304958a69cb4STejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZABLE) 3050f3421797STejun Heo for_each_cwq_cpu(cpu, wq) 3051a0a1a5fdSTejun Heo get_cwq(cpu, wq)->max_active = 0; 3052a0a1a5fdSTejun Heo 30533af24433SOleg Nesterov list_add(&wq->list, &workqueues); 3054a0a1a5fdSTejun Heo 30553af24433SOleg Nesterov spin_unlock(&workqueue_lock); 30563af24433SOleg Nesterov 30573af24433SOleg Nesterov return wq; 30584690c4abSTejun Heo err: 30594690c4abSTejun Heo if (wq) { 3060bdbc5dd7STejun Heo free_cwqs(wq); 3061f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 3062e22bee78STejun Heo kfree(wq->rescuer); 30634690c4abSTejun Heo kfree(wq); 30643af24433SOleg Nesterov } 30654690c4abSTejun Heo return NULL; 30661da177e4SLinus Torvalds } 3067d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 30681da177e4SLinus Torvalds 30693af24433SOleg Nesterov /** 30703af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 30713af24433SOleg Nesterov * @wq: target workqueue 30723af24433SOleg Nesterov * 30733af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 30743af24433SOleg Nesterov */ 30753af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 30763af24433SOleg Nesterov { 3077c8e55f36STejun Heo unsigned int cpu; 30783af24433SOleg Nesterov 30799c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 30809c5a2ba7STejun Heo drain_workqueue(wq); 3081c8efcc25STejun Heo 3082a0a1a5fdSTejun Heo /* 3083a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 3084a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 3085a0a1a5fdSTejun Heo */ 308695402b38SGautham R Shenoy spin_lock(&workqueue_lock); 30873af24433SOleg Nesterov list_del(&wq->list); 308895402b38SGautham R Shenoy spin_unlock(&workqueue_lock); 30893af24433SOleg Nesterov 3090e22bee78STejun Heo /* sanity check */ 3091f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 309273f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 309373f53c4aSTejun Heo int i; 30943af24433SOleg Nesterov 309573f53c4aSTejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 309673f53c4aSTejun Heo BUG_ON(cwq->nr_in_flight[i]); 30971e19ffc6STejun Heo BUG_ON(cwq->nr_active); 30981e19ffc6STejun Heo BUG_ON(!list_empty(&cwq->delayed_works)); 309973f53c4aSTejun Heo } 31001537663fSTejun Heo 3101e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 3102e22bee78STejun Heo kthread_stop(wq->rescuer->task); 3103f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 31048d9df9f0SXiaotian Feng kfree(wq->rescuer); 3105e22bee78STejun Heo } 3106e22bee78STejun Heo 3107bdbc5dd7STejun Heo free_cwqs(wq); 31083af24433SOleg Nesterov kfree(wq); 31093af24433SOleg Nesterov } 31103af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 31113af24433SOleg Nesterov 3112dcd989cbSTejun Heo /** 3113dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 3114dcd989cbSTejun Heo * @wq: target workqueue 3115dcd989cbSTejun Heo * @max_active: new max_active value. 3116dcd989cbSTejun Heo * 3117dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 3118dcd989cbSTejun Heo * 3119dcd989cbSTejun Heo * CONTEXT: 3120dcd989cbSTejun Heo * Don't call from IRQ context. 3121dcd989cbSTejun Heo */ 3122dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 3123dcd989cbSTejun Heo { 3124dcd989cbSTejun Heo unsigned int cpu; 3125dcd989cbSTejun Heo 3126f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 3127dcd989cbSTejun Heo 3128dcd989cbSTejun Heo spin_lock(&workqueue_lock); 3129dcd989cbSTejun Heo 3130dcd989cbSTejun Heo wq->saved_max_active = max_active; 3131dcd989cbSTejun Heo 3132f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 3133dcd989cbSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3134dcd989cbSTejun Heo 3135dcd989cbSTejun Heo spin_lock_irq(&gcwq->lock); 3136dcd989cbSTejun Heo 313758a69cb4STejun Heo if (!(wq->flags & WQ_FREEZABLE) || 3138dcd989cbSTejun Heo !(gcwq->flags & GCWQ_FREEZING)) 3139dcd989cbSTejun Heo get_cwq(gcwq->cpu, wq)->max_active = max_active; 3140dcd989cbSTejun Heo 3141dcd989cbSTejun Heo spin_unlock_irq(&gcwq->lock); 3142dcd989cbSTejun Heo } 3143dcd989cbSTejun Heo 3144dcd989cbSTejun Heo spin_unlock(&workqueue_lock); 3145dcd989cbSTejun Heo } 3146dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 3147dcd989cbSTejun Heo 3148dcd989cbSTejun Heo /** 3149dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 3150dcd989cbSTejun Heo * @cpu: CPU in question 3151dcd989cbSTejun Heo * @wq: target workqueue 3152dcd989cbSTejun Heo * 3153dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 3154dcd989cbSTejun Heo * no synchronization around this function and the test result is 3155dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3156dcd989cbSTejun Heo * 3157dcd989cbSTejun Heo * RETURNS: 3158dcd989cbSTejun Heo * %true if congested, %false otherwise. 3159dcd989cbSTejun Heo */ 3160dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 3161dcd989cbSTejun Heo { 3162dcd989cbSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3163dcd989cbSTejun Heo 3164dcd989cbSTejun Heo return !list_empty(&cwq->delayed_works); 3165dcd989cbSTejun Heo } 3166dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 3167dcd989cbSTejun Heo 3168dcd989cbSTejun Heo /** 3169dcd989cbSTejun Heo * work_cpu - return the last known associated cpu for @work 3170dcd989cbSTejun Heo * @work: the work of interest 3171dcd989cbSTejun Heo * 3172dcd989cbSTejun Heo * RETURNS: 3173bdbc5dd7STejun Heo * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. 3174dcd989cbSTejun Heo */ 3175dcd989cbSTejun Heo unsigned int work_cpu(struct work_struct *work) 3176dcd989cbSTejun Heo { 3177dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3178dcd989cbSTejun Heo 3179bdbc5dd7STejun Heo return gcwq ? gcwq->cpu : WORK_CPU_NONE; 3180dcd989cbSTejun Heo } 3181dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_cpu); 3182dcd989cbSTejun Heo 3183dcd989cbSTejun Heo /** 3184dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 3185dcd989cbSTejun Heo * @work: the work to be tested 3186dcd989cbSTejun Heo * 3187dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 3188dcd989cbSTejun Heo * synchronization around this function and the test result is 3189dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3190dcd989cbSTejun Heo * Especially for reentrant wqs, the pending state might hide the 3191dcd989cbSTejun Heo * running state. 3192dcd989cbSTejun Heo * 3193dcd989cbSTejun Heo * RETURNS: 3194dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 3195dcd989cbSTejun Heo */ 3196dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 3197dcd989cbSTejun Heo { 3198dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3199dcd989cbSTejun Heo unsigned long flags; 3200dcd989cbSTejun Heo unsigned int ret = 0; 3201dcd989cbSTejun Heo 3202dcd989cbSTejun Heo if (!gcwq) 3203dcd989cbSTejun Heo return false; 3204dcd989cbSTejun Heo 3205dcd989cbSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 3206dcd989cbSTejun Heo 3207dcd989cbSTejun Heo if (work_pending(work)) 3208dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 3209dcd989cbSTejun Heo if (find_worker_executing_work(gcwq, work)) 3210dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 3211dcd989cbSTejun Heo 3212dcd989cbSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 3213dcd989cbSTejun Heo 3214dcd989cbSTejun Heo return ret; 3215dcd989cbSTejun Heo } 3216dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 3217dcd989cbSTejun Heo 3218db7bccf4STejun Heo /* 3219db7bccf4STejun Heo * CPU hotplug. 3220db7bccf4STejun Heo * 3221e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 3222e22bee78STejun Heo * are a lot of assumptions on strong associations among work, cwq and 3223e22bee78STejun Heo * gcwq which make migrating pending and scheduled works very 3224e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 3225e22bee78STejun Heo * gcwqs serve mix of short, long and very long running works making 3226e22bee78STejun Heo * blocked draining impractical. 3227e22bee78STejun Heo * 3228e22bee78STejun Heo * This is solved by allowing a gcwq to be detached from CPU, running 3229e22bee78STejun Heo * it with unbound (rogue) workers and allowing it to be reattached 3230e22bee78STejun Heo * later if the cpu comes back online. A separate thread is created 3231e22bee78STejun Heo * to govern a gcwq in such state and is called the trustee of the 3232e22bee78STejun Heo * gcwq. 3233db7bccf4STejun Heo * 3234db7bccf4STejun Heo * Trustee states and their descriptions. 3235db7bccf4STejun Heo * 3236db7bccf4STejun Heo * START Command state used on startup. On CPU_DOWN_PREPARE, a 3237db7bccf4STejun Heo * new trustee is started with this state. 3238db7bccf4STejun Heo * 3239db7bccf4STejun Heo * IN_CHARGE Once started, trustee will enter this state after 3240e22bee78STejun Heo * assuming the manager role and making all existing 3241e22bee78STejun Heo * workers rogue. DOWN_PREPARE waits for trustee to 3242e22bee78STejun Heo * enter this state. After reaching IN_CHARGE, trustee 3243e22bee78STejun Heo * tries to execute the pending worklist until it's empty 3244e22bee78STejun Heo * and the state is set to BUTCHER, or the state is set 3245e22bee78STejun Heo * to RELEASE. 3246db7bccf4STejun Heo * 3247db7bccf4STejun Heo * BUTCHER Command state which is set by the cpu callback after 3248db7bccf4STejun Heo * the cpu has went down. Once this state is set trustee 3249db7bccf4STejun Heo * knows that there will be no new works on the worklist 3250db7bccf4STejun Heo * and once the worklist is empty it can proceed to 3251db7bccf4STejun Heo * killing idle workers. 3252db7bccf4STejun Heo * 3253db7bccf4STejun Heo * RELEASE Command state which is set by the cpu callback if the 3254db7bccf4STejun Heo * cpu down has been canceled or it has come online 3255db7bccf4STejun Heo * again. After recognizing this state, trustee stops 3256e22bee78STejun Heo * trying to drain or butcher and clears ROGUE, rebinds 3257e22bee78STejun Heo * all remaining workers back to the cpu and releases 3258e22bee78STejun Heo * manager role. 3259db7bccf4STejun Heo * 3260db7bccf4STejun Heo * DONE Trustee will enter this state after BUTCHER or RELEASE 3261db7bccf4STejun Heo * is complete. 3262db7bccf4STejun Heo * 3263db7bccf4STejun Heo * trustee CPU draining 3264db7bccf4STejun Heo * took over down complete 3265db7bccf4STejun Heo * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE 3266db7bccf4STejun Heo * | | ^ 3267db7bccf4STejun Heo * | CPU is back online v return workers | 3268db7bccf4STejun Heo * ----------------> RELEASE -------------- 3269db7bccf4STejun Heo */ 3270db7bccf4STejun Heo 3271db7bccf4STejun Heo /** 3272db7bccf4STejun Heo * trustee_wait_event_timeout - timed event wait for trustee 3273db7bccf4STejun Heo * @cond: condition to wait for 3274db7bccf4STejun Heo * @timeout: timeout in jiffies 3275db7bccf4STejun Heo * 3276db7bccf4STejun Heo * wait_event_timeout() for trustee to use. Handles locking and 3277db7bccf4STejun Heo * checks for RELEASE request. 3278db7bccf4STejun Heo * 3279db7bccf4STejun Heo * CONTEXT: 3280db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3281db7bccf4STejun Heo * multiple times. To be used by trustee. 3282db7bccf4STejun Heo * 3283db7bccf4STejun Heo * RETURNS: 3284db7bccf4STejun Heo * Positive indicating left time if @cond is satisfied, 0 if timed 3285db7bccf4STejun Heo * out, -1 if canceled. 3286db7bccf4STejun Heo */ 3287db7bccf4STejun Heo #define trustee_wait_event_timeout(cond, timeout) ({ \ 3288db7bccf4STejun Heo long __ret = (timeout); \ 3289db7bccf4STejun Heo while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ 3290db7bccf4STejun Heo __ret) { \ 3291db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); \ 3292db7bccf4STejun Heo __wait_event_timeout(gcwq->trustee_wait, (cond) || \ 3293db7bccf4STejun Heo (gcwq->trustee_state == TRUSTEE_RELEASE), \ 3294db7bccf4STejun Heo __ret); \ 3295db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); \ 3296db7bccf4STejun Heo } \ 3297db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ 3298db7bccf4STejun Heo }) 3299db7bccf4STejun Heo 3300db7bccf4STejun Heo /** 3301db7bccf4STejun Heo * trustee_wait_event - event wait for trustee 3302db7bccf4STejun Heo * @cond: condition to wait for 3303db7bccf4STejun Heo * 3304db7bccf4STejun Heo * wait_event() for trustee to use. Automatically handles locking and 3305db7bccf4STejun Heo * checks for CANCEL request. 3306db7bccf4STejun Heo * 3307db7bccf4STejun Heo * CONTEXT: 3308db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3309db7bccf4STejun Heo * multiple times. To be used by trustee. 3310db7bccf4STejun Heo * 3311db7bccf4STejun Heo * RETURNS: 3312db7bccf4STejun Heo * 0 if @cond is satisfied, -1 if canceled. 3313db7bccf4STejun Heo */ 3314db7bccf4STejun Heo #define trustee_wait_event(cond) ({ \ 3315db7bccf4STejun Heo long __ret1; \ 3316db7bccf4STejun Heo __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ 3317db7bccf4STejun Heo __ret1 < 0 ? -1 : 0; \ 3318db7bccf4STejun Heo }) 3319db7bccf4STejun Heo 3320db7bccf4STejun Heo static int __cpuinit trustee_thread(void *__gcwq) 3321db7bccf4STejun Heo { 3322db7bccf4STejun Heo struct global_cwq *gcwq = __gcwq; 3323db7bccf4STejun Heo struct worker *worker; 3324e22bee78STejun Heo struct work_struct *work; 3325db7bccf4STejun Heo struct hlist_node *pos; 3326e22bee78STejun Heo long rc; 3327db7bccf4STejun Heo int i; 3328db7bccf4STejun Heo 3329db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3330db7bccf4STejun Heo 3331db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3332db7bccf4STejun Heo /* 3333e22bee78STejun Heo * Claim the manager position and make all workers rogue. 3334e22bee78STejun Heo * Trustee must be bound to the target cpu and can't be 3335e22bee78STejun Heo * cancelled. 3336db7bccf4STejun Heo */ 3337db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3338e22bee78STejun Heo rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); 3339e22bee78STejun Heo BUG_ON(rc < 0); 3340e22bee78STejun Heo 3341e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 3342db7bccf4STejun Heo 3343db7bccf4STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) 3344cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3345db7bccf4STejun Heo 3346db7bccf4STejun Heo for_each_busy_worker(worker, i, pos, gcwq) 3347cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3348db7bccf4STejun Heo 3349db7bccf4STejun Heo /* 3350e22bee78STejun Heo * Call schedule() so that we cross rq->lock and thus can 3351e22bee78STejun Heo * guarantee sched callbacks see the rogue flag. This is 3352e22bee78STejun Heo * necessary as scheduler callbacks may be invoked from other 3353e22bee78STejun Heo * cpus. 3354e22bee78STejun Heo */ 3355e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3356e22bee78STejun Heo schedule(); 3357e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3358e22bee78STejun Heo 3359e22bee78STejun Heo /* 3360cb444766STejun Heo * Sched callbacks are disabled now. Zap nr_running. After 3361cb444766STejun Heo * this, nr_running stays zero and need_more_worker() and 3362cb444766STejun Heo * keep_working() are always true as long as the worklist is 3363cb444766STejun Heo * not empty. 3364e22bee78STejun Heo */ 3365cb444766STejun Heo atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); 3366e22bee78STejun Heo 3367e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3368e22bee78STejun Heo del_timer_sync(&gcwq->idle_timer); 3369e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3370e22bee78STejun Heo 3371e22bee78STejun Heo /* 3372db7bccf4STejun Heo * We're now in charge. Notify and proceed to drain. We need 3373db7bccf4STejun Heo * to keep the gcwq running during the whole CPU down 3374db7bccf4STejun Heo * procedure as other cpu hotunplug callbacks may need to 3375db7bccf4STejun Heo * flush currently running tasks. 3376db7bccf4STejun Heo */ 3377db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_IN_CHARGE; 3378db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3379db7bccf4STejun Heo 3380db7bccf4STejun Heo /* 3381db7bccf4STejun Heo * The original cpu is in the process of dying and may go away 3382db7bccf4STejun Heo * anytime now. When that happens, we and all workers would 3383e22bee78STejun Heo * be migrated to other cpus. Try draining any left work. We 3384e22bee78STejun Heo * want to get it over with ASAP - spam rescuers, wake up as 3385e22bee78STejun Heo * many idlers as necessary and create new ones till the 3386e22bee78STejun Heo * worklist is empty. Note that if the gcwq is frozen, there 338758a69cb4STejun Heo * may be frozen works in freezable cwqs. Don't declare 3388e22bee78STejun Heo * completion while frozen. 3389db7bccf4STejun Heo */ 3390db7bccf4STejun Heo while (gcwq->nr_workers != gcwq->nr_idle || 3391db7bccf4STejun Heo gcwq->flags & GCWQ_FREEZING || 3392db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_IN_CHARGE) { 3393e22bee78STejun Heo int nr_works = 0; 3394e22bee78STejun Heo 3395e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) { 3396e22bee78STejun Heo send_mayday(work); 3397e22bee78STejun Heo nr_works++; 3398e22bee78STejun Heo } 3399e22bee78STejun Heo 3400e22bee78STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) { 3401e22bee78STejun Heo if (!nr_works--) 3402e22bee78STejun Heo break; 3403e22bee78STejun Heo wake_up_process(worker->task); 3404e22bee78STejun Heo } 3405e22bee78STejun Heo 3406e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 3407e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3408e22bee78STejun Heo worker = create_worker(gcwq, false); 3409e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3410e22bee78STejun Heo if (worker) { 3411cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3412e22bee78STejun Heo start_worker(worker); 3413e22bee78STejun Heo } 3414e22bee78STejun Heo } 3415e22bee78STejun Heo 3416db7bccf4STejun Heo /* give a breather */ 3417db7bccf4STejun Heo if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) 3418db7bccf4STejun Heo break; 3419db7bccf4STejun Heo } 3420db7bccf4STejun Heo 3421e22bee78STejun Heo /* 3422e22bee78STejun Heo * Either all works have been scheduled and cpu is down, or 3423e22bee78STejun Heo * cpu down has already been canceled. Wait for and butcher 3424e22bee78STejun Heo * all workers till we're canceled. 3425e22bee78STejun Heo */ 3426e22bee78STejun Heo do { 3427e22bee78STejun Heo rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); 3428e22bee78STejun Heo while (!list_empty(&gcwq->idle_list)) 3429e22bee78STejun Heo destroy_worker(list_first_entry(&gcwq->idle_list, 3430e22bee78STejun Heo struct worker, entry)); 3431e22bee78STejun Heo } while (gcwq->nr_workers && rc >= 0); 3432e22bee78STejun Heo 3433e22bee78STejun Heo /* 3434e22bee78STejun Heo * At this point, either draining has completed and no worker 3435e22bee78STejun Heo * is left, or cpu down has been canceled or the cpu is being 3436e22bee78STejun Heo * brought back up. There shouldn't be any idle one left. 3437e22bee78STejun Heo * Tell the remaining busy ones to rebind once it finishes the 3438e22bee78STejun Heo * currently scheduled works by scheduling the rebind_work. 3439e22bee78STejun Heo */ 3440e22bee78STejun Heo WARN_ON(!list_empty(&gcwq->idle_list)); 3441e22bee78STejun Heo 3442e22bee78STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 3443e22bee78STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 3444e22bee78STejun Heo 3445e22bee78STejun Heo /* 3446e22bee78STejun Heo * Rebind_work may race with future cpu hotplug 3447e22bee78STejun Heo * operations. Use a separate flag to mark that 3448e22bee78STejun Heo * rebinding is scheduled. 3449e22bee78STejun Heo */ 3450cb444766STejun Heo worker->flags |= WORKER_REBIND; 3451cb444766STejun Heo worker->flags &= ~WORKER_ROGUE; 3452e22bee78STejun Heo 3453e22bee78STejun Heo /* queue rebind_work, wq doesn't matter, use the default one */ 3454e22bee78STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 3455e22bee78STejun Heo work_data_bits(rebind_work))) 3456e22bee78STejun Heo continue; 3457e22bee78STejun Heo 3458e22bee78STejun Heo debug_work_activate(rebind_work); 3459d320c038STejun Heo insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, 3460e22bee78STejun Heo worker->scheduled.next, 3461e22bee78STejun Heo work_color_to_flags(WORK_NO_COLOR)); 3462e22bee78STejun Heo } 3463e22bee78STejun Heo 3464e22bee78STejun Heo /* relinquish manager role */ 3465e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 3466e22bee78STejun Heo 3467db7bccf4STejun Heo /* notify completion */ 3468db7bccf4STejun Heo gcwq->trustee = NULL; 3469db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3470db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3471db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3472db7bccf4STejun Heo return 0; 3473db7bccf4STejun Heo } 3474db7bccf4STejun Heo 3475db7bccf4STejun Heo /** 3476db7bccf4STejun Heo * wait_trustee_state - wait for trustee to enter the specified state 3477db7bccf4STejun Heo * @gcwq: gcwq the trustee of interest belongs to 3478db7bccf4STejun Heo * @state: target state to wait for 3479db7bccf4STejun Heo * 3480db7bccf4STejun Heo * Wait for the trustee to reach @state. DONE is already matched. 3481db7bccf4STejun Heo * 3482db7bccf4STejun Heo * CONTEXT: 3483db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3484db7bccf4STejun Heo * multiple times. To be used by cpu_callback. 3485db7bccf4STejun Heo */ 3486db7bccf4STejun Heo static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) 348706bd6ebfSNamhyung Kim __releases(&gcwq->lock) 348806bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 3489db7bccf4STejun Heo { 3490db7bccf4STejun Heo if (!(gcwq->trustee_state == state || 3491db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE)) { 3492db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3493db7bccf4STejun Heo __wait_event(gcwq->trustee_wait, 3494db7bccf4STejun Heo gcwq->trustee_state == state || 3495db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE); 3496db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3497db7bccf4STejun Heo } 3498db7bccf4STejun Heo } 3499db7bccf4STejun Heo 35009c7b216dSChandra Seetharaman static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 35011da177e4SLinus Torvalds unsigned long action, 35021da177e4SLinus Torvalds void *hcpu) 35031da177e4SLinus Torvalds { 35043af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 3505db7bccf4STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3506db7bccf4STejun Heo struct task_struct *new_trustee = NULL; 3507e22bee78STejun Heo struct worker *uninitialized_var(new_worker); 3508db7bccf4STejun Heo unsigned long flags; 35091da177e4SLinus Torvalds 35108bb78442SRafael J. Wysocki action &= ~CPU_TASKS_FROZEN; 35118bb78442SRafael J. Wysocki 35121da177e4SLinus Torvalds switch (action) { 3513db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3514db7bccf4STejun Heo new_trustee = kthread_create(trustee_thread, gcwq, 3515db7bccf4STejun Heo "workqueue_trustee/%d\n", cpu); 3516db7bccf4STejun Heo if (IS_ERR(new_trustee)) 3517db7bccf4STejun Heo return notifier_from_errno(PTR_ERR(new_trustee)); 3518db7bccf4STejun Heo kthread_bind(new_trustee, cpu); 3519e22bee78STejun Heo /* fall through */ 35203af24433SOleg Nesterov case CPU_UP_PREPARE: 3521e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3522e22bee78STejun Heo new_worker = create_worker(gcwq, false); 3523e22bee78STejun Heo if (!new_worker) { 3524e22bee78STejun Heo if (new_trustee) 3525e22bee78STejun Heo kthread_stop(new_trustee); 3526e22bee78STejun Heo return NOTIFY_BAD; 35273af24433SOleg Nesterov } 3528db7bccf4STejun Heo } 35291537663fSTejun Heo 3530db7bccf4STejun Heo /* some are called w/ irq disabled, don't disturb irq status */ 3531db7bccf4STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 35323af24433SOleg Nesterov 35333af24433SOleg Nesterov switch (action) { 3534db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3535db7bccf4STejun Heo /* initialize trustee and tell it to acquire the gcwq */ 3536db7bccf4STejun Heo BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); 3537db7bccf4STejun Heo gcwq->trustee = new_trustee; 3538db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_START; 3539db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3540db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); 3541e22bee78STejun Heo /* fall through */ 35423af24433SOleg Nesterov case CPU_UP_PREPARE: 3543e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3544e22bee78STejun Heo gcwq->first_idle = new_worker; 35451da177e4SLinus Torvalds break; 35461da177e4SLinus Torvalds 3547e22bee78STejun Heo case CPU_DYING: 3548e22bee78STejun Heo /* 3549e22bee78STejun Heo * Before this, the trustee and all workers except for 3550e22bee78STejun Heo * the ones which are still executing works from 3551e22bee78STejun Heo * before the last CPU down must be on the cpu. After 3552e22bee78STejun Heo * this, they'll all be diasporas. 3553e22bee78STejun Heo */ 3554e22bee78STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 3555db7bccf4STejun Heo break; 3556db7bccf4STejun Heo 35573da1c84cSOleg Nesterov case CPU_POST_DEAD: 3558db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_BUTCHER; 3559e22bee78STejun Heo /* fall through */ 3560e22bee78STejun Heo case CPU_UP_CANCELED: 3561e22bee78STejun Heo destroy_worker(gcwq->first_idle); 3562e22bee78STejun Heo gcwq->first_idle = NULL; 3563db7bccf4STejun Heo break; 3564db7bccf4STejun Heo 3565db7bccf4STejun Heo case CPU_DOWN_FAILED: 35661da177e4SLinus Torvalds case CPU_ONLINE: 3567e22bee78STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3568db7bccf4STejun Heo if (gcwq->trustee_state != TRUSTEE_DONE) { 3569db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_RELEASE; 3570db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3571db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_DONE); 3572db7bccf4STejun Heo } 35731da177e4SLinus Torvalds 3574e22bee78STejun Heo /* 3575e22bee78STejun Heo * Trustee is done and there might be no worker left. 3576e22bee78STejun Heo * Put the first_idle in and request a real manager to 3577e22bee78STejun Heo * take a look. 3578e22bee78STejun Heo */ 3579e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3580e22bee78STejun Heo kthread_bind(gcwq->first_idle->task, cpu); 3581e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3582e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 3583e22bee78STejun Heo start_worker(gcwq->first_idle); 3584e22bee78STejun Heo gcwq->first_idle = NULL; 35851da177e4SLinus Torvalds break; 35861da177e4SLinus Torvalds } 35871da177e4SLinus Torvalds 3588db7bccf4STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 358900dfcaf7SOleg Nesterov 35901537663fSTejun Heo return notifier_from_errno(0); 35911da177e4SLinus Torvalds } 35921da177e4SLinus Torvalds 35932d3854a3SRusty Russell #ifdef CONFIG_SMP 35948ccad40dSRusty Russell 35952d3854a3SRusty Russell struct work_for_cpu { 35966b44003eSAndrew Morton struct completion completion; 35972d3854a3SRusty Russell long (*fn)(void *); 35982d3854a3SRusty Russell void *arg; 35992d3854a3SRusty Russell long ret; 36002d3854a3SRusty Russell }; 36012d3854a3SRusty Russell 36026b44003eSAndrew Morton static int do_work_for_cpu(void *_wfc) 36032d3854a3SRusty Russell { 36046b44003eSAndrew Morton struct work_for_cpu *wfc = _wfc; 36052d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 36066b44003eSAndrew Morton complete(&wfc->completion); 36076b44003eSAndrew Morton return 0; 36082d3854a3SRusty Russell } 36092d3854a3SRusty Russell 36102d3854a3SRusty Russell /** 36112d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 36122d3854a3SRusty Russell * @cpu: the cpu to run on 36132d3854a3SRusty Russell * @fn: the function to run 36142d3854a3SRusty Russell * @arg: the function arg 36152d3854a3SRusty Russell * 361631ad9081SRusty Russell * This will return the value @fn returns. 361731ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 36186b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 36192d3854a3SRusty Russell */ 36202d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 36212d3854a3SRusty Russell { 36226b44003eSAndrew Morton struct task_struct *sub_thread; 36236b44003eSAndrew Morton struct work_for_cpu wfc = { 36246b44003eSAndrew Morton .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), 36256b44003eSAndrew Morton .fn = fn, 36266b44003eSAndrew Morton .arg = arg, 36276b44003eSAndrew Morton }; 36282d3854a3SRusty Russell 36296b44003eSAndrew Morton sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); 36306b44003eSAndrew Morton if (IS_ERR(sub_thread)) 36316b44003eSAndrew Morton return PTR_ERR(sub_thread); 36326b44003eSAndrew Morton kthread_bind(sub_thread, cpu); 36336b44003eSAndrew Morton wake_up_process(sub_thread); 36346b44003eSAndrew Morton wait_for_completion(&wfc.completion); 36352d3854a3SRusty Russell return wfc.ret; 36362d3854a3SRusty Russell } 36372d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 36382d3854a3SRusty Russell #endif /* CONFIG_SMP */ 36392d3854a3SRusty Russell 3640a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3641e7577c50SRusty Russell 3642a0a1a5fdSTejun Heo /** 3643a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3644a0a1a5fdSTejun Heo * 364558a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 364658a69cb4STejun Heo * workqueues will queue new works to their frozen_works list instead of 364758a69cb4STejun Heo * gcwq->worklist. 3648a0a1a5fdSTejun Heo * 3649a0a1a5fdSTejun Heo * CONTEXT: 36508b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3651a0a1a5fdSTejun Heo */ 3652a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3653a0a1a5fdSTejun Heo { 3654a0a1a5fdSTejun Heo unsigned int cpu; 3655a0a1a5fdSTejun Heo 3656a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3657a0a1a5fdSTejun Heo 3658a0a1a5fdSTejun Heo BUG_ON(workqueue_freezing); 3659a0a1a5fdSTejun Heo workqueue_freezing = true; 3660a0a1a5fdSTejun Heo 3661f3421797STejun Heo for_each_gcwq_cpu(cpu) { 36628b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3663bdbc5dd7STejun Heo struct workqueue_struct *wq; 36648b03ae3cSTejun Heo 36658b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 36668b03ae3cSTejun Heo 3667db7bccf4STejun Heo BUG_ON(gcwq->flags & GCWQ_FREEZING); 3668db7bccf4STejun Heo gcwq->flags |= GCWQ_FREEZING; 3669db7bccf4STejun Heo 3670a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3671a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3672a0a1a5fdSTejun Heo 367358a69cb4STejun Heo if (cwq && wq->flags & WQ_FREEZABLE) 3674a0a1a5fdSTejun Heo cwq->max_active = 0; 36751da177e4SLinus Torvalds } 36768b03ae3cSTejun Heo 36778b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3678a0a1a5fdSTejun Heo } 3679a0a1a5fdSTejun Heo 3680a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3681a0a1a5fdSTejun Heo } 3682a0a1a5fdSTejun Heo 3683a0a1a5fdSTejun Heo /** 368458a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 3685a0a1a5fdSTejun Heo * 3686a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3687a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3688a0a1a5fdSTejun Heo * 3689a0a1a5fdSTejun Heo * CONTEXT: 3690a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3691a0a1a5fdSTejun Heo * 3692a0a1a5fdSTejun Heo * RETURNS: 369358a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 369458a69cb4STejun Heo * is complete. 3695a0a1a5fdSTejun Heo */ 3696a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3697a0a1a5fdSTejun Heo { 3698a0a1a5fdSTejun Heo unsigned int cpu; 3699a0a1a5fdSTejun Heo bool busy = false; 3700a0a1a5fdSTejun Heo 3701a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3702a0a1a5fdSTejun Heo 3703a0a1a5fdSTejun Heo BUG_ON(!workqueue_freezing); 3704a0a1a5fdSTejun Heo 3705f3421797STejun Heo for_each_gcwq_cpu(cpu) { 3706bdbc5dd7STejun Heo struct workqueue_struct *wq; 3707a0a1a5fdSTejun Heo /* 3708a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3709a0a1a5fdSTejun Heo * to peek without lock. 3710a0a1a5fdSTejun Heo */ 3711a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3712a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3713a0a1a5fdSTejun Heo 371458a69cb4STejun Heo if (!cwq || !(wq->flags & WQ_FREEZABLE)) 3715a0a1a5fdSTejun Heo continue; 3716a0a1a5fdSTejun Heo 3717a0a1a5fdSTejun Heo BUG_ON(cwq->nr_active < 0); 3718a0a1a5fdSTejun Heo if (cwq->nr_active) { 3719a0a1a5fdSTejun Heo busy = true; 3720a0a1a5fdSTejun Heo goto out_unlock; 3721a0a1a5fdSTejun Heo } 3722a0a1a5fdSTejun Heo } 3723a0a1a5fdSTejun Heo } 3724a0a1a5fdSTejun Heo out_unlock: 3725a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3726a0a1a5fdSTejun Heo return busy; 3727a0a1a5fdSTejun Heo } 3728a0a1a5fdSTejun Heo 3729a0a1a5fdSTejun Heo /** 3730a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3731a0a1a5fdSTejun Heo * 3732a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 37337e11629dSTejun Heo * frozen works are transferred to their respective gcwq worklists. 3734a0a1a5fdSTejun Heo * 3735a0a1a5fdSTejun Heo * CONTEXT: 37368b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3737a0a1a5fdSTejun Heo */ 3738a0a1a5fdSTejun Heo void thaw_workqueues(void) 3739a0a1a5fdSTejun Heo { 3740a0a1a5fdSTejun Heo unsigned int cpu; 3741a0a1a5fdSTejun Heo 3742a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3743a0a1a5fdSTejun Heo 3744a0a1a5fdSTejun Heo if (!workqueue_freezing) 3745a0a1a5fdSTejun Heo goto out_unlock; 3746a0a1a5fdSTejun Heo 3747f3421797STejun Heo for_each_gcwq_cpu(cpu) { 37488b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3749bdbc5dd7STejun Heo struct workqueue_struct *wq; 37508b03ae3cSTejun Heo 37518b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 37528b03ae3cSTejun Heo 3753db7bccf4STejun Heo BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); 3754db7bccf4STejun Heo gcwq->flags &= ~GCWQ_FREEZING; 3755db7bccf4STejun Heo 3756a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3757a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3758a0a1a5fdSTejun Heo 375958a69cb4STejun Heo if (!cwq || !(wq->flags & WQ_FREEZABLE)) 3760a0a1a5fdSTejun Heo continue; 3761a0a1a5fdSTejun Heo 3762a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 3763a0a1a5fdSTejun Heo cwq->max_active = wq->saved_max_active; 3764a0a1a5fdSTejun Heo 3765a0a1a5fdSTejun Heo while (!list_empty(&cwq->delayed_works) && 3766a0a1a5fdSTejun Heo cwq->nr_active < cwq->max_active) 3767a0a1a5fdSTejun Heo cwq_activate_first_delayed(cwq); 3768a0a1a5fdSTejun Heo } 37698b03ae3cSTejun Heo 3770e22bee78STejun Heo wake_up_worker(gcwq); 3771e22bee78STejun Heo 37728b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3773a0a1a5fdSTejun Heo } 3774a0a1a5fdSTejun Heo 3775a0a1a5fdSTejun Heo workqueue_freezing = false; 3776a0a1a5fdSTejun Heo out_unlock: 3777a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3778a0a1a5fdSTejun Heo } 3779a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3780a0a1a5fdSTejun Heo 37816ee0578bSSuresh Siddha static int __init init_workqueues(void) 37821da177e4SLinus Torvalds { 3783c34056a3STejun Heo unsigned int cpu; 3784c8e55f36STejun Heo int i; 3785c34056a3STejun Heo 3786f6500947STejun Heo cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); 37878b03ae3cSTejun Heo 37888b03ae3cSTejun Heo /* initialize gcwqs */ 3789f3421797STejun Heo for_each_gcwq_cpu(cpu) { 37908b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 37918b03ae3cSTejun Heo 37928b03ae3cSTejun Heo spin_lock_init(&gcwq->lock); 37937e11629dSTejun Heo INIT_LIST_HEAD(&gcwq->worklist); 37948b03ae3cSTejun Heo gcwq->cpu = cpu; 3795f3421797STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 37968b03ae3cSTejun Heo 3797c8e55f36STejun Heo INIT_LIST_HEAD(&gcwq->idle_list); 3798c8e55f36STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) 3799c8e55f36STejun Heo INIT_HLIST_HEAD(&gcwq->busy_hash[i]); 3800c8e55f36STejun Heo 3801e22bee78STejun Heo init_timer_deferrable(&gcwq->idle_timer); 3802e22bee78STejun Heo gcwq->idle_timer.function = idle_worker_timeout; 3803e22bee78STejun Heo gcwq->idle_timer.data = (unsigned long)gcwq; 3804e22bee78STejun Heo 3805e22bee78STejun Heo setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, 3806e22bee78STejun Heo (unsigned long)gcwq); 3807e22bee78STejun Heo 38088b03ae3cSTejun Heo ida_init(&gcwq->worker_ida); 3809db7bccf4STejun Heo 3810db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3811db7bccf4STejun Heo init_waitqueue_head(&gcwq->trustee_wait); 38128b03ae3cSTejun Heo } 38138b03ae3cSTejun Heo 3814e22bee78STejun Heo /* create the initial worker */ 3815f3421797STejun Heo for_each_online_gcwq_cpu(cpu) { 3816e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3817e22bee78STejun Heo struct worker *worker; 3818e22bee78STejun Heo 3819477a3c33STejun Heo if (cpu != WORK_CPU_UNBOUND) 3820477a3c33STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3821e22bee78STejun Heo worker = create_worker(gcwq, true); 3822e22bee78STejun Heo BUG_ON(!worker); 3823e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3824e22bee78STejun Heo start_worker(worker); 3825e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3826e22bee78STejun Heo } 3827e22bee78STejun Heo 3828d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 3829d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3830d320c038STejun Heo system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); 3831f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3832f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 383324d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 383424d51addSTejun Heo WQ_FREEZABLE, 0); 383562d3c543SAlan Stern system_nrt_freezable_wq = alloc_workqueue("events_nrt_freezable", 383662d3c543SAlan Stern WQ_NON_REENTRANT | WQ_FREEZABLE, 0); 3837e5cba24eSHitoshi Mitake BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq || 383862d3c543SAlan Stern !system_unbound_wq || !system_freezable_wq || 383962d3c543SAlan Stern !system_nrt_freezable_wq); 38406ee0578bSSuresh Siddha return 0; 38411da177e4SLinus Torvalds } 38426ee0578bSSuresh Siddha early_initcall(init_workqueues); 3843