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 261da177e4SLinus Torvalds #include <linux/module.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 82e22bee78STejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */ 83e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 84e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 85db7bccf4STejun Heo TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ 861da177e4SLinus Torvalds 871da177e4SLinus Torvalds /* 88e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 89e22bee78STejun Heo * all cpus. Give -20. 90e22bee78STejun Heo */ 91e22bee78STejun Heo RESCUER_NICE_LEVEL = -20, 92c8e55f36STejun Heo }; 93c8e55f36STejun Heo 941da177e4SLinus Torvalds /* 954690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 964690c4abSTejun Heo * 97e41e704bSTejun Heo * I: Modifiable by initialization/destruction paths and read-only for 98e41e704bSTejun Heo * everyone else. 994690c4abSTejun Heo * 100e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 101e22bee78STejun Heo * only be modified and accessed from the local cpu. 102e22bee78STejun Heo * 1038b03ae3cSTejun Heo * L: gcwq->lock protected. Access with gcwq->lock held. 1044690c4abSTejun Heo * 105e22bee78STejun Heo * X: During normal operation, modification requires gcwq->lock and 106e22bee78STejun Heo * should be done only from local cpu. Either disabling preemption 107e22bee78STejun Heo * on local cpu or grabbing gcwq->lock is enough for read access. 108f3421797STejun Heo * If GCWQ_DISASSOCIATED is set, it's identical to L. 109e22bee78STejun Heo * 11073f53c4aSTejun Heo * F: wq->flush_mutex protected. 11173f53c4aSTejun Heo * 1124690c4abSTejun Heo * W: workqueue_lock protected. 1134690c4abSTejun Heo */ 1144690c4abSTejun Heo 1158b03ae3cSTejun Heo struct global_cwq; 116c34056a3STejun Heo 117e22bee78STejun Heo /* 118e22bee78STejun Heo * The poor guys doing the actual heavy lifting. All on-duty workers 119e22bee78STejun Heo * are either serving the manager role, on idle list or on busy hash. 120e22bee78STejun Heo */ 121c34056a3STejun Heo struct worker { 122c8e55f36STejun Heo /* on idle list while idle, on busy hash table while busy */ 123c8e55f36STejun Heo union { 124c8e55f36STejun Heo struct list_head entry; /* L: while idle */ 125c8e55f36STejun Heo struct hlist_node hentry; /* L: while busy */ 126c8e55f36STejun Heo }; 127c8e55f36STejun Heo 128c34056a3STejun Heo struct work_struct *current_work; /* L: work being processed */ 1298cca0eeaSTejun Heo struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ 130affee4b2STejun Heo struct list_head scheduled; /* L: scheduled works */ 131c34056a3STejun Heo struct task_struct *task; /* I: worker task */ 1328b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 133e22bee78STejun Heo /* 64 bytes boundary on 64bit, 32 on 32bit */ 134e22bee78STejun Heo unsigned long last_active; /* L: last active timestamp */ 135e22bee78STejun Heo unsigned int flags; /* X: flags */ 136c34056a3STejun Heo int id; /* I: worker id */ 137e22bee78STejun Heo struct work_struct rebind_work; /* L: rebind worker to cpu */ 138c34056a3STejun Heo }; 139c34056a3STejun Heo 1404690c4abSTejun Heo /* 141e22bee78STejun Heo * Global per-cpu workqueue. There's one and only one for each cpu 142e22bee78STejun Heo * and all works are queued and processed here regardless of their 143e22bee78STejun Heo * target workqueues. 1448b03ae3cSTejun Heo */ 1458b03ae3cSTejun Heo struct global_cwq { 1468b03ae3cSTejun Heo spinlock_t lock; /* the gcwq lock */ 1477e11629dSTejun Heo struct list_head worklist; /* L: list of pending works */ 1488b03ae3cSTejun Heo unsigned int cpu; /* I: the associated cpu */ 149db7bccf4STejun Heo unsigned int flags; /* L: GCWQ_* flags */ 150c8e55f36STejun Heo 151c8e55f36STejun Heo int nr_workers; /* L: total number of workers */ 152c8e55f36STejun Heo int nr_idle; /* L: currently idle ones */ 153c8e55f36STejun Heo 154c8e55f36STejun Heo /* workers are chained either in the idle_list or busy_hash */ 155e22bee78STejun Heo struct list_head idle_list; /* X: list of idle workers */ 156c8e55f36STejun Heo struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; 157c8e55f36STejun Heo /* L: hash of busy workers */ 158c8e55f36STejun Heo 159e22bee78STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 160e22bee78STejun Heo struct timer_list mayday_timer; /* L: SOS timer for dworkers */ 161e22bee78STejun Heo 1628b03ae3cSTejun Heo struct ida worker_ida; /* L: for worker IDs */ 163db7bccf4STejun Heo 164db7bccf4STejun Heo struct task_struct *trustee; /* L: for gcwq shutdown */ 165db7bccf4STejun Heo unsigned int trustee_state; /* L: trustee state */ 166db7bccf4STejun Heo wait_queue_head_t trustee_wait; /* trustee wait */ 167e22bee78STejun Heo struct worker *first_idle; /* L: first idle worker */ 1688b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1698b03ae3cSTejun Heo 1708b03ae3cSTejun Heo /* 171502ca9d8STejun Heo * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of 1720f900049STejun Heo * work_struct->data are used for flags and thus cwqs need to be 1730f900049STejun Heo * aligned at two's power of the number of flag bits. 1741da177e4SLinus Torvalds */ 1751da177e4SLinus Torvalds struct cpu_workqueue_struct { 1768b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 1774690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 17873f53c4aSTejun Heo int work_color; /* L: current color */ 17973f53c4aSTejun Heo int flush_color; /* L: flushing color */ 18073f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 18173f53c4aSTejun Heo /* L: nr of in_flight works */ 1821e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 183a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 1841e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 1850f900049STejun Heo }; 1861da177e4SLinus Torvalds 1871da177e4SLinus Torvalds /* 18873f53c4aSTejun Heo * Structure used to wait for workqueue flush. 18973f53c4aSTejun Heo */ 19073f53c4aSTejun Heo struct wq_flusher { 19173f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 19273f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 19373f53c4aSTejun Heo struct completion done; /* flush completion */ 19473f53c4aSTejun Heo }; 1951da177e4SLinus Torvalds 19673f53c4aSTejun Heo /* 197f2e005aaSTejun Heo * All cpumasks are assumed to be always set on UP and thus can't be 198f2e005aaSTejun Heo * used to determine whether there's something to be done. 199f2e005aaSTejun Heo */ 200f2e005aaSTejun Heo #ifdef CONFIG_SMP 201f2e005aaSTejun Heo typedef cpumask_var_t mayday_mask_t; 202f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) \ 203f2e005aaSTejun Heo cpumask_test_and_set_cpu((cpu), (mask)) 204f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) 205f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) 2069c37547aSTejun Heo #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) 207f2e005aaSTejun Heo #define free_mayday_mask(mask) free_cpumask_var((mask)) 208f2e005aaSTejun Heo #else 209f2e005aaSTejun Heo typedef unsigned long mayday_mask_t; 210f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) 211f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) 212f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) 213f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) true 214f2e005aaSTejun Heo #define free_mayday_mask(mask) do { } while (0) 215f2e005aaSTejun Heo #endif 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds /* 2181da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 2191da177e4SLinus Torvalds * per-CPU workqueues: 2201da177e4SLinus Torvalds */ 2211da177e4SLinus Torvalds struct workqueue_struct { 22297e37d7bSTejun Heo unsigned int flags; /* I: WQ_* flags */ 223bdbc5dd7STejun Heo union { 224bdbc5dd7STejun Heo struct cpu_workqueue_struct __percpu *pcpu; 225bdbc5dd7STejun Heo struct cpu_workqueue_struct *single; 226bdbc5dd7STejun Heo unsigned long v; 227bdbc5dd7STejun Heo } cpu_wq; /* I: cwq's */ 2284690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 22973f53c4aSTejun Heo 23073f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 23173f53c4aSTejun Heo int work_color; /* F: current work color */ 23273f53c4aSTejun Heo int flush_color; /* F: current flush color */ 23373f53c4aSTejun Heo atomic_t nr_cwqs_to_flush; /* flush in progress */ 23473f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 23573f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 23673f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 23773f53c4aSTejun Heo 238f2e005aaSTejun Heo mayday_mask_t mayday_mask; /* cpus requesting rescue */ 239e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 240e22bee78STejun Heo 241dcd989cbSTejun Heo int saved_max_active; /* W: saved cwq max_active */ 2424690c4abSTejun Heo const char *name; /* I: workqueue name */ 2434e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2444e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2454e6045f1SJohannes Berg #endif 2461da177e4SLinus Torvalds }; 2471da177e4SLinus Torvalds 248d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 249d320c038STejun Heo struct workqueue_struct *system_long_wq __read_mostly; 250d320c038STejun Heo struct workqueue_struct *system_nrt_wq __read_mostly; 251f3421797STejun Heo struct workqueue_struct *system_unbound_wq __read_mostly; 252d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 253d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 254d320c038STejun Heo EXPORT_SYMBOL_GPL(system_nrt_wq); 255f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 256d320c038STejun Heo 25797bd2347STejun Heo #define CREATE_TRACE_POINTS 25897bd2347STejun Heo #include <trace/events/workqueue.h> 25997bd2347STejun Heo 260db7bccf4STejun Heo #define for_each_busy_worker(worker, i, pos, gcwq) \ 261db7bccf4STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ 262db7bccf4STejun Heo hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) 263db7bccf4STejun Heo 264f3421797STejun Heo static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, 265f3421797STejun Heo unsigned int sw) 266f3421797STejun Heo { 267f3421797STejun Heo if (cpu < nr_cpu_ids) { 268f3421797STejun Heo if (sw & 1) { 269f3421797STejun Heo cpu = cpumask_next(cpu, mask); 270f3421797STejun Heo if (cpu < nr_cpu_ids) 271f3421797STejun Heo return cpu; 272f3421797STejun Heo } 273f3421797STejun Heo if (sw & 2) 274f3421797STejun Heo return WORK_CPU_UNBOUND; 275f3421797STejun Heo } 276f3421797STejun Heo return WORK_CPU_NONE; 277f3421797STejun Heo } 278f3421797STejun Heo 279f3421797STejun Heo static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, 280f3421797STejun Heo struct workqueue_struct *wq) 281f3421797STejun Heo { 282f3421797STejun Heo return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); 283f3421797STejun Heo } 284f3421797STejun Heo 28509884951STejun Heo /* 28609884951STejun Heo * CPU iterators 28709884951STejun Heo * 28809884951STejun Heo * An extra gcwq is defined for an invalid cpu number 28909884951STejun Heo * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any 29009884951STejun Heo * specific CPU. The following iterators are similar to 29109884951STejun Heo * for_each_*_cpu() iterators but also considers the unbound gcwq. 29209884951STejun Heo * 29309884951STejun Heo * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND 29409884951STejun Heo * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND 29509884951STejun Heo * for_each_cwq_cpu() : possible CPUs for bound workqueues, 29609884951STejun Heo * WORK_CPU_UNBOUND for unbound workqueues 29709884951STejun Heo */ 298f3421797STejun Heo #define for_each_gcwq_cpu(cpu) \ 299f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ 300f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 301f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) 302f3421797STejun Heo 303f3421797STejun Heo #define for_each_online_gcwq_cpu(cpu) \ 304f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ 305f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 306f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) 307f3421797STejun Heo 308f3421797STejun Heo #define for_each_cwq_cpu(cpu, wq) \ 309f3421797STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ 310f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 311f3421797STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) 312f3421797STejun Heo 313a25909a4SPaul E. McKenney #ifdef CONFIG_LOCKDEP 314a25909a4SPaul E. McKenney /** 315a25909a4SPaul E. McKenney * in_workqueue_context() - in context of specified workqueue? 316a25909a4SPaul E. McKenney * @wq: the workqueue of interest 317a25909a4SPaul E. McKenney * 318a25909a4SPaul E. McKenney * Checks lockdep state to see if the current task is executing from 319a25909a4SPaul E. McKenney * within a workqueue item. This function exists only if lockdep is 320a25909a4SPaul E. McKenney * enabled. 321a25909a4SPaul E. McKenney */ 322a25909a4SPaul E. McKenney int in_workqueue_context(struct workqueue_struct *wq) 323a25909a4SPaul E. McKenney { 324a25909a4SPaul E. McKenney return lock_is_held(&wq->lockdep_map); 325a25909a4SPaul E. McKenney } 326a25909a4SPaul E. McKenney #endif 327a25909a4SPaul E. McKenney 328dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 329dc186ad7SThomas Gleixner 330dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 331dc186ad7SThomas Gleixner 332dc186ad7SThomas Gleixner /* 333dc186ad7SThomas Gleixner * fixup_init is called when: 334dc186ad7SThomas Gleixner * - an active object is initialized 335dc186ad7SThomas Gleixner */ 336dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 337dc186ad7SThomas Gleixner { 338dc186ad7SThomas Gleixner struct work_struct *work = addr; 339dc186ad7SThomas Gleixner 340dc186ad7SThomas Gleixner switch (state) { 341dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 342dc186ad7SThomas Gleixner cancel_work_sync(work); 343dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 344dc186ad7SThomas Gleixner return 1; 345dc186ad7SThomas Gleixner default: 346dc186ad7SThomas Gleixner return 0; 347dc186ad7SThomas Gleixner } 348dc186ad7SThomas Gleixner } 349dc186ad7SThomas Gleixner 350dc186ad7SThomas Gleixner /* 351dc186ad7SThomas Gleixner * fixup_activate is called when: 352dc186ad7SThomas Gleixner * - an active object is activated 353dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 354dc186ad7SThomas Gleixner */ 355dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 356dc186ad7SThomas Gleixner { 357dc186ad7SThomas Gleixner struct work_struct *work = addr; 358dc186ad7SThomas Gleixner 359dc186ad7SThomas Gleixner switch (state) { 360dc186ad7SThomas Gleixner 361dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 362dc186ad7SThomas Gleixner /* 363dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 364dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 365dc186ad7SThomas Gleixner * is tracked in the object tracker. 366dc186ad7SThomas Gleixner */ 36722df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 368dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 369dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 370dc186ad7SThomas Gleixner return 0; 371dc186ad7SThomas Gleixner } 372dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 373dc186ad7SThomas Gleixner return 0; 374dc186ad7SThomas Gleixner 375dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 376dc186ad7SThomas Gleixner WARN_ON(1); 377dc186ad7SThomas Gleixner 378dc186ad7SThomas Gleixner default: 379dc186ad7SThomas Gleixner return 0; 380dc186ad7SThomas Gleixner } 381dc186ad7SThomas Gleixner } 382dc186ad7SThomas Gleixner 383dc186ad7SThomas Gleixner /* 384dc186ad7SThomas Gleixner * fixup_free is called when: 385dc186ad7SThomas Gleixner * - an active object is freed 386dc186ad7SThomas Gleixner */ 387dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 388dc186ad7SThomas Gleixner { 389dc186ad7SThomas Gleixner struct work_struct *work = addr; 390dc186ad7SThomas Gleixner 391dc186ad7SThomas Gleixner switch (state) { 392dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 393dc186ad7SThomas Gleixner cancel_work_sync(work); 394dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 395dc186ad7SThomas Gleixner return 1; 396dc186ad7SThomas Gleixner default: 397dc186ad7SThomas Gleixner return 0; 398dc186ad7SThomas Gleixner } 399dc186ad7SThomas Gleixner } 400dc186ad7SThomas Gleixner 401dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 402dc186ad7SThomas Gleixner .name = "work_struct", 403dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 404dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 405dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 406dc186ad7SThomas Gleixner }; 407dc186ad7SThomas Gleixner 408dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 409dc186ad7SThomas Gleixner { 410dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 411dc186ad7SThomas Gleixner } 412dc186ad7SThomas Gleixner 413dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 414dc186ad7SThomas Gleixner { 415dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 416dc186ad7SThomas Gleixner } 417dc186ad7SThomas Gleixner 418dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 419dc186ad7SThomas Gleixner { 420dc186ad7SThomas Gleixner if (onstack) 421dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 422dc186ad7SThomas Gleixner else 423dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 424dc186ad7SThomas Gleixner } 425dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 426dc186ad7SThomas Gleixner 427dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 428dc186ad7SThomas Gleixner { 429dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 430dc186ad7SThomas Gleixner } 431dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 432dc186ad7SThomas Gleixner 433dc186ad7SThomas Gleixner #else 434dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 435dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 436dc186ad7SThomas Gleixner #endif 437dc186ad7SThomas Gleixner 43895402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 43995402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 4401da177e4SLinus Torvalds static LIST_HEAD(workqueues); 441a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 4421da177e4SLinus Torvalds 44314441960SOleg Nesterov /* 444e22bee78STejun Heo * The almighty global cpu workqueues. nr_running is the only field 445e22bee78STejun Heo * which is expected to be used frequently by other cpus via 446e22bee78STejun Heo * try_to_wake_up(). Put it in a separate cacheline. 44714441960SOleg Nesterov */ 4488b03ae3cSTejun Heo static DEFINE_PER_CPU(struct global_cwq, global_cwq); 449e22bee78STejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); 450f756d5e2SNathan Lynch 451f3421797STejun Heo /* 452f3421797STejun Heo * Global cpu workqueue and nr_running counter for unbound gcwq. The 453f3421797STejun Heo * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its 454f3421797STejun Heo * workers have WORKER_UNBOUND set. 455f3421797STejun Heo */ 456f3421797STejun Heo static struct global_cwq unbound_global_cwq; 457f3421797STejun Heo static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ 458f3421797STejun Heo 459c34056a3STejun Heo static int worker_thread(void *__worker); 4601da177e4SLinus Torvalds 4618b03ae3cSTejun Heo static struct global_cwq *get_gcwq(unsigned int cpu) 4621da177e4SLinus Torvalds { 463f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 4648b03ae3cSTejun Heo return &per_cpu(global_cwq, cpu); 465f3421797STejun Heo else 466f3421797STejun Heo return &unbound_global_cwq; 4671da177e4SLinus Torvalds } 4681da177e4SLinus Torvalds 469e22bee78STejun Heo static atomic_t *get_gcwq_nr_running(unsigned int cpu) 470b1f4ec17SOleg Nesterov { 471f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 472e22bee78STejun Heo return &per_cpu(gcwq_nr_running, cpu); 473f3421797STejun Heo else 474f3421797STejun Heo return &unbound_gcwq_nr_running; 475b1f4ec17SOleg Nesterov } 476b1f4ec17SOleg Nesterov 4774690c4abSTejun Heo static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, 4784690c4abSTejun Heo struct workqueue_struct *wq) 479a848e3b6SOleg Nesterov { 480f3421797STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 481f3421797STejun Heo if (likely(cpu < nr_cpu_ids)) { 482f3421797STejun Heo #ifdef CONFIG_SMP 483bdbc5dd7STejun Heo return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); 484f3421797STejun Heo #else 485f3421797STejun Heo return wq->cpu_wq.single; 486bdbc5dd7STejun Heo #endif 487a848e3b6SOleg Nesterov } 488f3421797STejun Heo } else if (likely(cpu == WORK_CPU_UNBOUND)) 489f3421797STejun Heo return wq->cpu_wq.single; 490f3421797STejun Heo return NULL; 491f3421797STejun Heo } 492a848e3b6SOleg Nesterov 49373f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 49473f53c4aSTejun Heo { 49573f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 49673f53c4aSTejun Heo } 49773f53c4aSTejun Heo 49873f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 49973f53c4aSTejun Heo { 50073f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 50173f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 50273f53c4aSTejun Heo } 50373f53c4aSTejun Heo 50473f53c4aSTejun Heo static int work_next_color(int color) 50573f53c4aSTejun Heo { 50673f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 5071da177e4SLinus Torvalds } 5081da177e4SLinus Torvalds 5094594bf15SDavid Howells /* 510e120153dSTejun Heo * A work's data points to the cwq with WORK_STRUCT_CWQ set while the 511e120153dSTejun Heo * work is on queue. Once execution starts, WORK_STRUCT_CWQ is 512e120153dSTejun Heo * cleared and the work data contains the cpu number it was last on. 5137a22ad75STejun Heo * 5147a22ad75STejun Heo * set_work_{cwq|cpu}() and clear_work_data() can be used to set the 5157a22ad75STejun Heo * cwq, cpu or clear work->data. These functions should only be 5167a22ad75STejun Heo * called while the work is owned - ie. while the PENDING bit is set. 5177a22ad75STejun Heo * 5187a22ad75STejun Heo * get_work_[g]cwq() can be used to obtain the gcwq or cwq 5197a22ad75STejun Heo * corresponding to a work. gcwq is available once the work has been 5207a22ad75STejun Heo * queued anywhere after initialization. cwq is available only from 5217a22ad75STejun Heo * queueing until execution starts. 5224594bf15SDavid Howells */ 5237a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 5247a22ad75STejun Heo unsigned long flags) 5257a22ad75STejun Heo { 5267a22ad75STejun Heo BUG_ON(!work_pending(work)); 5277a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 5287a22ad75STejun Heo } 5297a22ad75STejun Heo 5307a22ad75STejun Heo static void set_work_cwq(struct work_struct *work, 5314690c4abSTejun Heo struct cpu_workqueue_struct *cwq, 5324690c4abSTejun Heo unsigned long extra_flags) 533365970a1SDavid Howells { 5347a22ad75STejun Heo set_work_data(work, (unsigned long)cwq, 535e120153dSTejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); 536365970a1SDavid Howells } 537365970a1SDavid Howells 5387a22ad75STejun Heo static void set_work_cpu(struct work_struct *work, unsigned int cpu) 5394d707b9fSOleg Nesterov { 5407a22ad75STejun Heo set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); 5414d707b9fSOleg Nesterov } 5424d707b9fSOleg Nesterov 5437a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 544365970a1SDavid Howells { 5457a22ad75STejun Heo set_work_data(work, WORK_STRUCT_NO_CPU, 0); 5467a22ad75STejun Heo } 5477a22ad75STejun Heo 5487a22ad75STejun Heo static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) 5497a22ad75STejun Heo { 550e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5517a22ad75STejun Heo 552e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 553e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 554e120153dSTejun Heo else 555e120153dSTejun Heo return NULL; 5567a22ad75STejun Heo } 5577a22ad75STejun Heo 5587a22ad75STejun Heo static struct global_cwq *get_work_gcwq(struct work_struct *work) 5597a22ad75STejun Heo { 560e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5617a22ad75STejun Heo unsigned int cpu; 5627a22ad75STejun Heo 563e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 564e120153dSTejun Heo return ((struct cpu_workqueue_struct *) 565e120153dSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; 5667a22ad75STejun Heo 5677a22ad75STejun Heo cpu = data >> WORK_STRUCT_FLAG_BITS; 568bdbc5dd7STejun Heo if (cpu == WORK_CPU_NONE) 5697a22ad75STejun Heo return NULL; 5707a22ad75STejun Heo 571f3421797STejun Heo BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); 5727a22ad75STejun Heo return get_gcwq(cpu); 573365970a1SDavid Howells } 574365970a1SDavid Howells 575e22bee78STejun Heo /* 576e22bee78STejun Heo * Policy functions. These define the policies on how the global 577e22bee78STejun Heo * worker pool is managed. Unless noted otherwise, these functions 578e22bee78STejun Heo * assume that they're being called with gcwq->lock held. 579e22bee78STejun Heo */ 580e22bee78STejun Heo 581649027d7STejun Heo static bool __need_more_worker(struct global_cwq *gcwq) 582649027d7STejun Heo { 583649027d7STejun Heo return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || 584649027d7STejun Heo gcwq->flags & GCWQ_HIGHPRI_PENDING; 585649027d7STejun Heo } 586649027d7STejun Heo 587e22bee78STejun Heo /* 588e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 589e22bee78STejun Heo * running workers. 590e22bee78STejun Heo */ 591e22bee78STejun Heo static bool need_more_worker(struct global_cwq *gcwq) 592e22bee78STejun Heo { 593649027d7STejun Heo return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); 594e22bee78STejun Heo } 595e22bee78STejun Heo 596e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 597e22bee78STejun Heo static bool may_start_working(struct global_cwq *gcwq) 598e22bee78STejun Heo { 599e22bee78STejun Heo return gcwq->nr_idle; 600e22bee78STejun Heo } 601e22bee78STejun Heo 602e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 603e22bee78STejun Heo static bool keep_working(struct global_cwq *gcwq) 604e22bee78STejun Heo { 605e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 606e22bee78STejun Heo 607e22bee78STejun Heo return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1; 608e22bee78STejun Heo } 609e22bee78STejun Heo 610e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 611e22bee78STejun Heo static bool need_to_create_worker(struct global_cwq *gcwq) 612e22bee78STejun Heo { 613e22bee78STejun Heo return need_more_worker(gcwq) && !may_start_working(gcwq); 614e22bee78STejun Heo } 615e22bee78STejun Heo 616e22bee78STejun Heo /* Do I need to be the manager? */ 617e22bee78STejun Heo static bool need_to_manage_workers(struct global_cwq *gcwq) 618e22bee78STejun Heo { 619e22bee78STejun Heo return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; 620e22bee78STejun Heo } 621e22bee78STejun Heo 622e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 623e22bee78STejun Heo static bool too_many_workers(struct global_cwq *gcwq) 624e22bee78STejun Heo { 625e22bee78STejun Heo bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; 626e22bee78STejun Heo int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ 627e22bee78STejun Heo int nr_busy = gcwq->nr_workers - nr_idle; 628e22bee78STejun Heo 629e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 630e22bee78STejun Heo } 631e22bee78STejun Heo 632e22bee78STejun Heo /* 633e22bee78STejun Heo * Wake up functions. 634e22bee78STejun Heo */ 635e22bee78STejun Heo 6367e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 6377e11629dSTejun Heo static struct worker *first_worker(struct global_cwq *gcwq) 6387e11629dSTejun Heo { 6397e11629dSTejun Heo if (unlikely(list_empty(&gcwq->idle_list))) 6407e11629dSTejun Heo return NULL; 6417e11629dSTejun Heo 6427e11629dSTejun Heo return list_first_entry(&gcwq->idle_list, struct worker, entry); 6437e11629dSTejun Heo } 6447e11629dSTejun Heo 6457e11629dSTejun Heo /** 6467e11629dSTejun Heo * wake_up_worker - wake up an idle worker 6477e11629dSTejun Heo * @gcwq: gcwq to wake worker for 6487e11629dSTejun Heo * 6497e11629dSTejun Heo * Wake up the first idle worker of @gcwq. 6507e11629dSTejun Heo * 6517e11629dSTejun Heo * CONTEXT: 6527e11629dSTejun Heo * spin_lock_irq(gcwq->lock). 6537e11629dSTejun Heo */ 6547e11629dSTejun Heo static void wake_up_worker(struct global_cwq *gcwq) 6557e11629dSTejun Heo { 6567e11629dSTejun Heo struct worker *worker = first_worker(gcwq); 6577e11629dSTejun Heo 6587e11629dSTejun Heo if (likely(worker)) 6597e11629dSTejun Heo wake_up_process(worker->task); 6607e11629dSTejun Heo } 6617e11629dSTejun Heo 6624690c4abSTejun Heo /** 663e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 664e22bee78STejun Heo * @task: task waking up 665e22bee78STejun Heo * @cpu: CPU @task is waking up to 666e22bee78STejun Heo * 667e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 668e22bee78STejun Heo * being awoken. 669e22bee78STejun Heo * 670e22bee78STejun Heo * CONTEXT: 671e22bee78STejun Heo * spin_lock_irq(rq->lock) 672e22bee78STejun Heo */ 673e22bee78STejun Heo void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) 674e22bee78STejun Heo { 675e22bee78STejun Heo struct worker *worker = kthread_data(task); 676e22bee78STejun Heo 677e22bee78STejun Heo if (likely(!(worker->flags & WORKER_NOT_RUNNING))) 678e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(cpu)); 679e22bee78STejun Heo } 680e22bee78STejun Heo 681e22bee78STejun Heo /** 682e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 683e22bee78STejun Heo * @task: task going to sleep 684e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 685e22bee78STejun Heo * 686e22bee78STejun Heo * This function is called during schedule() when a busy worker is 687e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 688e22bee78STejun Heo * returning pointer to its task. 689e22bee78STejun Heo * 690e22bee78STejun Heo * CONTEXT: 691e22bee78STejun Heo * spin_lock_irq(rq->lock) 692e22bee78STejun Heo * 693e22bee78STejun Heo * RETURNS: 694e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 695e22bee78STejun Heo */ 696e22bee78STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, 697e22bee78STejun Heo unsigned int cpu) 698e22bee78STejun Heo { 699e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 700e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 701e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(cpu); 702e22bee78STejun Heo 703e22bee78STejun Heo if (unlikely(worker->flags & WORKER_NOT_RUNNING)) 704e22bee78STejun Heo return NULL; 705e22bee78STejun Heo 706e22bee78STejun Heo /* this can only happen on the local cpu */ 707e22bee78STejun Heo BUG_ON(cpu != raw_smp_processor_id()); 708e22bee78STejun Heo 709e22bee78STejun Heo /* 710e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 711e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 712e22bee78STejun Heo * Please read comment there. 713e22bee78STejun Heo * 714e22bee78STejun Heo * NOT_RUNNING is clear. This means that trustee is not in 715e22bee78STejun Heo * charge and we're running on the local cpu w/ rq lock held 716e22bee78STejun Heo * and preemption disabled, which in turn means that none else 717e22bee78STejun Heo * could be manipulating idle_list, so dereferencing idle_list 718e22bee78STejun Heo * without gcwq lock is safe. 719e22bee78STejun Heo */ 720e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) 721e22bee78STejun Heo to_wakeup = first_worker(gcwq); 722e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 723e22bee78STejun Heo } 724e22bee78STejun Heo 725e22bee78STejun Heo /** 726e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 727cb444766STejun Heo * @worker: self 728d302f017STejun Heo * @flags: flags to set 729d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 730d302f017STejun Heo * 731e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 732e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 733e22bee78STejun Heo * woken up. 734d302f017STejun Heo * 735cb444766STejun Heo * CONTEXT: 736cb444766STejun Heo * spin_lock_irq(gcwq->lock) 737d302f017STejun Heo */ 738d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 739d302f017STejun Heo bool wakeup) 740d302f017STejun Heo { 741e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 742e22bee78STejun Heo 743cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 744cb444766STejun Heo 745e22bee78STejun Heo /* 746e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 747e22bee78STejun Heo * wake up an idle worker as necessary if requested by 748e22bee78STejun Heo * @wakeup. 749e22bee78STejun Heo */ 750e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 751e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 752e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 753e22bee78STejun Heo 754e22bee78STejun Heo if (wakeup) { 755e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && 756e22bee78STejun Heo !list_empty(&gcwq->worklist)) 757e22bee78STejun Heo wake_up_worker(gcwq); 758e22bee78STejun Heo } else 759e22bee78STejun Heo atomic_dec(nr_running); 760e22bee78STejun Heo } 761e22bee78STejun Heo 762d302f017STejun Heo worker->flags |= flags; 763d302f017STejun Heo } 764d302f017STejun Heo 765d302f017STejun Heo /** 766e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 767cb444766STejun Heo * @worker: self 768d302f017STejun Heo * @flags: flags to clear 769d302f017STejun Heo * 770e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 771d302f017STejun Heo * 772cb444766STejun Heo * CONTEXT: 773cb444766STejun Heo * spin_lock_irq(gcwq->lock) 774d302f017STejun Heo */ 775d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 776d302f017STejun Heo { 777e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 778e22bee78STejun Heo unsigned int oflags = worker->flags; 779e22bee78STejun Heo 780cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 781cb444766STejun Heo 782d302f017STejun Heo worker->flags &= ~flags; 783e22bee78STejun Heo 784e22bee78STejun Heo /* if transitioning out of NOT_RUNNING, increment nr_running */ 785e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 786e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 787e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(gcwq->cpu)); 788d302f017STejun Heo } 789d302f017STejun Heo 790d302f017STejun Heo /** 791c8e55f36STejun Heo * busy_worker_head - return the busy hash head for a work 792c8e55f36STejun Heo * @gcwq: gcwq of interest 793c8e55f36STejun Heo * @work: work to be hashed 794c8e55f36STejun Heo * 795c8e55f36STejun Heo * Return hash head of @gcwq for @work. 796c8e55f36STejun Heo * 797c8e55f36STejun Heo * CONTEXT: 798c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 799c8e55f36STejun Heo * 800c8e55f36STejun Heo * RETURNS: 801c8e55f36STejun Heo * Pointer to the hash head. 802c8e55f36STejun Heo */ 803c8e55f36STejun Heo static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, 804c8e55f36STejun Heo struct work_struct *work) 805c8e55f36STejun Heo { 806c8e55f36STejun Heo const int base_shift = ilog2(sizeof(struct work_struct)); 807c8e55f36STejun Heo unsigned long v = (unsigned long)work; 808c8e55f36STejun Heo 809c8e55f36STejun Heo /* simple shift and fold hash, do we need something better? */ 810c8e55f36STejun Heo v >>= base_shift; 811c8e55f36STejun Heo v += v >> BUSY_WORKER_HASH_ORDER; 812c8e55f36STejun Heo v &= BUSY_WORKER_HASH_MASK; 813c8e55f36STejun Heo 814c8e55f36STejun Heo return &gcwq->busy_hash[v]; 815c8e55f36STejun Heo } 816c8e55f36STejun Heo 817c8e55f36STejun Heo /** 8188cca0eeaSTejun Heo * __find_worker_executing_work - find worker which is executing a work 8198cca0eeaSTejun Heo * @gcwq: gcwq of interest 8208cca0eeaSTejun Heo * @bwh: hash head as returned by busy_worker_head() 8218cca0eeaSTejun Heo * @work: work to find worker for 8228cca0eeaSTejun Heo * 8238cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. @bwh should be 8248cca0eeaSTejun Heo * the hash head obtained by calling busy_worker_head() with the same 8258cca0eeaSTejun Heo * work. 8268cca0eeaSTejun Heo * 8278cca0eeaSTejun Heo * CONTEXT: 8288cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8298cca0eeaSTejun Heo * 8308cca0eeaSTejun Heo * RETURNS: 8318cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8328cca0eeaSTejun Heo * otherwise. 8338cca0eeaSTejun Heo */ 8348cca0eeaSTejun Heo static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, 8358cca0eeaSTejun Heo struct hlist_head *bwh, 8368cca0eeaSTejun Heo struct work_struct *work) 8378cca0eeaSTejun Heo { 8388cca0eeaSTejun Heo struct worker *worker; 8398cca0eeaSTejun Heo struct hlist_node *tmp; 8408cca0eeaSTejun Heo 8418cca0eeaSTejun Heo hlist_for_each_entry(worker, tmp, bwh, hentry) 8428cca0eeaSTejun Heo if (worker->current_work == work) 8438cca0eeaSTejun Heo return worker; 8448cca0eeaSTejun Heo return NULL; 8458cca0eeaSTejun Heo } 8468cca0eeaSTejun Heo 8478cca0eeaSTejun Heo /** 8488cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 8498cca0eeaSTejun Heo * @gcwq: gcwq of interest 8508cca0eeaSTejun Heo * @work: work to find worker for 8518cca0eeaSTejun Heo * 8528cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. This function is 8538cca0eeaSTejun Heo * identical to __find_worker_executing_work() except that this 8548cca0eeaSTejun Heo * function calculates @bwh itself. 8558cca0eeaSTejun Heo * 8568cca0eeaSTejun Heo * CONTEXT: 8578cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8588cca0eeaSTejun Heo * 8598cca0eeaSTejun Heo * RETURNS: 8608cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8618cca0eeaSTejun Heo * otherwise. 8628cca0eeaSTejun Heo */ 8638cca0eeaSTejun Heo static struct worker *find_worker_executing_work(struct global_cwq *gcwq, 8648cca0eeaSTejun Heo struct work_struct *work) 8658cca0eeaSTejun Heo { 8668cca0eeaSTejun Heo return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), 8678cca0eeaSTejun Heo work); 8688cca0eeaSTejun Heo } 8698cca0eeaSTejun Heo 8708cca0eeaSTejun Heo /** 871649027d7STejun Heo * gcwq_determine_ins_pos - find insertion position 872649027d7STejun Heo * @gcwq: gcwq of interest 873649027d7STejun Heo * @cwq: cwq a work is being queued for 874649027d7STejun Heo * 875649027d7STejun Heo * A work for @cwq is about to be queued on @gcwq, determine insertion 876649027d7STejun Heo * position for the work. If @cwq is for HIGHPRI wq, the work is 877649027d7STejun Heo * queued at the head of the queue but in FIFO order with respect to 878649027d7STejun Heo * other HIGHPRI works; otherwise, at the end of the queue. This 879649027d7STejun Heo * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that 880649027d7STejun Heo * there are HIGHPRI works pending. 881649027d7STejun Heo * 882649027d7STejun Heo * CONTEXT: 883649027d7STejun Heo * spin_lock_irq(gcwq->lock). 884649027d7STejun Heo * 885649027d7STejun Heo * RETURNS: 886649027d7STejun Heo * Pointer to inserstion position. 887649027d7STejun Heo */ 888649027d7STejun Heo static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, 8891da177e4SLinus Torvalds struct cpu_workqueue_struct *cwq) 8901da177e4SLinus Torvalds { 891649027d7STejun Heo struct work_struct *twork; 8921da177e4SLinus Torvalds 893649027d7STejun Heo if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) 894649027d7STejun Heo return &gcwq->worklist; 8951da177e4SLinus Torvalds 896649027d7STejun Heo list_for_each_entry(twork, &gcwq->worklist, entry) { 897649027d7STejun Heo struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); 898649027d7STejun Heo 899649027d7STejun Heo if (!(tcwq->wq->flags & WQ_HIGHPRI)) 900649027d7STejun Heo break; 9011da177e4SLinus Torvalds } 9021da177e4SLinus Torvalds 903649027d7STejun Heo gcwq->flags |= GCWQ_HIGHPRI_PENDING; 904649027d7STejun Heo return &twork->entry; 905649027d7STejun Heo } 906649027d7STejun Heo 907649027d7STejun Heo /** 9087e11629dSTejun Heo * insert_work - insert a work into gcwq 9094690c4abSTejun Heo * @cwq: cwq @work belongs to 9104690c4abSTejun Heo * @work: work to insert 9114690c4abSTejun Heo * @head: insertion point 9124690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 9134690c4abSTejun Heo * 9147e11629dSTejun Heo * Insert @work which belongs to @cwq into @gcwq after @head. 9157e11629dSTejun Heo * @extra_flags is or'd to work_struct flags. 9164690c4abSTejun Heo * 9174690c4abSTejun Heo * CONTEXT: 9188b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 9191da177e4SLinus Torvalds */ 920b89deed3SOleg Nesterov static void insert_work(struct cpu_workqueue_struct *cwq, 9214690c4abSTejun Heo struct work_struct *work, struct list_head *head, 9224690c4abSTejun Heo unsigned int extra_flags) 923b89deed3SOleg Nesterov { 924e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 925e1d8aa9fSFrederic Weisbecker 9264690c4abSTejun Heo /* we own @work, set data and link */ 9277a22ad75STejun Heo set_work_cwq(work, cwq, extra_flags); 9284690c4abSTejun Heo 9296e84d644SOleg Nesterov /* 9306e84d644SOleg Nesterov * Ensure that we get the right work->data if we see the 9316e84d644SOleg Nesterov * result of list_add() below, see try_to_grab_pending(). 9326e84d644SOleg Nesterov */ 9336e84d644SOleg Nesterov smp_wmb(); 9344690c4abSTejun Heo 9351a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 936e22bee78STejun Heo 937e22bee78STejun Heo /* 938e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 939e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 940e22bee78STejun Heo * lying around lazily while there are works to be processed. 941e22bee78STejun Heo */ 942e22bee78STejun Heo smp_mb(); 943e22bee78STejun Heo 944649027d7STejun Heo if (__need_more_worker(gcwq)) 945e22bee78STejun Heo wake_up_worker(gcwq); 946b89deed3SOleg Nesterov } 947b89deed3SOleg Nesterov 9484690c4abSTejun Heo static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 9491da177e4SLinus Torvalds struct work_struct *work) 9501da177e4SLinus Torvalds { 951502ca9d8STejun Heo struct global_cwq *gcwq; 952502ca9d8STejun Heo struct cpu_workqueue_struct *cwq; 9531e19ffc6STejun Heo struct list_head *worklist; 9548a2e8e5dSTejun Heo unsigned int work_flags; 9551da177e4SLinus Torvalds unsigned long flags; 9561da177e4SLinus Torvalds 957dc186ad7SThomas Gleixner debug_work_activate(work); 9581e19ffc6STejun Heo 959e41e704bSTejun Heo if (WARN_ON_ONCE(wq->flags & WQ_DYING)) 960e41e704bSTejun Heo return; 961e41e704bSTejun Heo 962c7fc77f7STejun Heo /* determine gcwq to use */ 963c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 964c7fc77f7STejun Heo struct global_cwq *last_gcwq; 965c7fc77f7STejun Heo 966f3421797STejun Heo if (unlikely(cpu == WORK_CPU_UNBOUND)) 967f3421797STejun Heo cpu = raw_smp_processor_id(); 968f3421797STejun Heo 96918aa9effSTejun Heo /* 97018aa9effSTejun Heo * It's multi cpu. If @wq is non-reentrant and @work 97118aa9effSTejun Heo * was previously on a different cpu, it might still 97218aa9effSTejun Heo * be running there, in which case the work needs to 97318aa9effSTejun Heo * be queued on that cpu to guarantee non-reentrance. 97418aa9effSTejun Heo */ 975502ca9d8STejun Heo gcwq = get_gcwq(cpu); 97618aa9effSTejun Heo if (wq->flags & WQ_NON_REENTRANT && 97718aa9effSTejun Heo (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { 97818aa9effSTejun Heo struct worker *worker; 97918aa9effSTejun Heo 98018aa9effSTejun Heo spin_lock_irqsave(&last_gcwq->lock, flags); 98118aa9effSTejun Heo 98218aa9effSTejun Heo worker = find_worker_executing_work(last_gcwq, work); 98318aa9effSTejun Heo 98418aa9effSTejun Heo if (worker && worker->current_cwq->wq == wq) 98518aa9effSTejun Heo gcwq = last_gcwq; 98618aa9effSTejun Heo else { 98718aa9effSTejun Heo /* meh... not running there, queue here */ 98818aa9effSTejun Heo spin_unlock_irqrestore(&last_gcwq->lock, flags); 98918aa9effSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 99018aa9effSTejun Heo } 99118aa9effSTejun Heo } else 9928b03ae3cSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 993f3421797STejun Heo } else { 994f3421797STejun Heo gcwq = get_gcwq(WORK_CPU_UNBOUND); 995f3421797STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 996502ca9d8STejun Heo } 997502ca9d8STejun Heo 998502ca9d8STejun Heo /* gcwq determined, get cwq and queue */ 999502ca9d8STejun Heo cwq = get_cwq(gcwq->cpu, wq); 1000502ca9d8STejun Heo 10014690c4abSTejun Heo BUG_ON(!list_empty(&work->entry)); 10021e19ffc6STejun Heo 100373f53c4aSTejun Heo cwq->nr_in_flight[cwq->work_color]++; 10048a2e8e5dSTejun Heo work_flags = work_color_to_flags(cwq->work_color); 10051e19ffc6STejun Heo 10061e19ffc6STejun Heo if (likely(cwq->nr_active < cwq->max_active)) { 10071e19ffc6STejun Heo cwq->nr_active++; 1008649027d7STejun Heo worklist = gcwq_determine_ins_pos(gcwq, cwq); 10098a2e8e5dSTejun Heo } else { 10108a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 10111e19ffc6STejun Heo worklist = &cwq->delayed_works; 10128a2e8e5dSTejun Heo } 10131e19ffc6STejun Heo 10148a2e8e5dSTejun Heo insert_work(cwq, work, worklist, work_flags); 10151e19ffc6STejun Heo 10168b03ae3cSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 10171da177e4SLinus Torvalds } 10181da177e4SLinus Torvalds 10190fcb78c2SRolf Eike Beer /** 10200fcb78c2SRolf Eike Beer * queue_work - queue work on a workqueue 10210fcb78c2SRolf Eike Beer * @wq: workqueue to use 10220fcb78c2SRolf Eike Beer * @work: work to queue 10230fcb78c2SRolf Eike Beer * 1024057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10251da177e4SLinus Torvalds * 102600dfcaf7SOleg Nesterov * We queue the work to the CPU on which it was submitted, but if the CPU dies 102700dfcaf7SOleg Nesterov * it can be processed by another CPU. 10281da177e4SLinus Torvalds */ 10297ad5b3a5SHarvey Harrison int queue_work(struct workqueue_struct *wq, struct work_struct *work) 10301da177e4SLinus Torvalds { 1031ef1ca236SOleg Nesterov int ret; 10321da177e4SLinus Torvalds 1033ef1ca236SOleg Nesterov ret = queue_work_on(get_cpu(), wq, work); 1034a848e3b6SOleg Nesterov put_cpu(); 1035ef1ca236SOleg Nesterov 10361da177e4SLinus Torvalds return ret; 10371da177e4SLinus Torvalds } 1038ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_work); 10391da177e4SLinus Torvalds 1040c1a220e7SZhang Rui /** 1041c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1042c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1043c1a220e7SZhang Rui * @wq: workqueue to use 1044c1a220e7SZhang Rui * @work: work to queue 1045c1a220e7SZhang Rui * 1046c1a220e7SZhang Rui * Returns 0 if @work was already on a queue, non-zero otherwise. 1047c1a220e7SZhang Rui * 1048c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1049c1a220e7SZhang Rui * can't go away. 1050c1a220e7SZhang Rui */ 1051c1a220e7SZhang Rui int 1052c1a220e7SZhang Rui queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) 1053c1a220e7SZhang Rui { 1054c1a220e7SZhang Rui int ret = 0; 1055c1a220e7SZhang Rui 105622df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 10574690c4abSTejun Heo __queue_work(cpu, wq, work); 1058c1a220e7SZhang Rui ret = 1; 1059c1a220e7SZhang Rui } 1060c1a220e7SZhang Rui return ret; 1061c1a220e7SZhang Rui } 1062c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1063c1a220e7SZhang Rui 10646d141c3fSLi Zefan static void delayed_work_timer_fn(unsigned long __data) 10651da177e4SLinus Torvalds { 106652bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 10677a22ad75STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); 10681da177e4SLinus Torvalds 10694690c4abSTejun Heo __queue_work(smp_processor_id(), cwq->wq, &dwork->work); 10701da177e4SLinus Torvalds } 10711da177e4SLinus Torvalds 10720fcb78c2SRolf Eike Beer /** 10730fcb78c2SRolf Eike Beer * queue_delayed_work - queue work on a workqueue after delay 10740fcb78c2SRolf Eike Beer * @wq: workqueue to use 1075af9997e4SRandy Dunlap * @dwork: delayable work to queue 10760fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10770fcb78c2SRolf Eike Beer * 1078057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10790fcb78c2SRolf Eike Beer */ 10807ad5b3a5SHarvey Harrison int queue_delayed_work(struct workqueue_struct *wq, 108152bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 10821da177e4SLinus Torvalds { 108352bad64dSDavid Howells if (delay == 0) 108463bc0362SOleg Nesterov return queue_work(wq, &dwork->work); 10851da177e4SLinus Torvalds 108663bc0362SOleg Nesterov return queue_delayed_work_on(-1, wq, dwork, delay); 10871da177e4SLinus Torvalds } 1088ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work); 10891da177e4SLinus Torvalds 10900fcb78c2SRolf Eike Beer /** 10910fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 10920fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 10930fcb78c2SRolf Eike Beer * @wq: workqueue to use 1094af9997e4SRandy Dunlap * @dwork: work to queue 10950fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10960fcb78c2SRolf Eike Beer * 1097057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10980fcb78c2SRolf Eike Beer */ 10997a6bc1cdSVenkatesh Pallipadi int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 110052bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 11017a6bc1cdSVenkatesh Pallipadi { 11027a6bc1cdSVenkatesh Pallipadi int ret = 0; 110352bad64dSDavid Howells struct timer_list *timer = &dwork->timer; 110452bad64dSDavid Howells struct work_struct *work = &dwork->work; 11057a6bc1cdSVenkatesh Pallipadi 110622df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 1107c7fc77f7STejun Heo unsigned int lcpu; 11087a22ad75STejun Heo 11097a6bc1cdSVenkatesh Pallipadi BUG_ON(timer_pending(timer)); 11107a6bc1cdSVenkatesh Pallipadi BUG_ON(!list_empty(&work->entry)); 11117a6bc1cdSVenkatesh Pallipadi 11128a3e77ccSAndrew Liu timer_stats_timer_set_start_info(&dwork->timer); 11138a3e77ccSAndrew Liu 11147a22ad75STejun Heo /* 11157a22ad75STejun Heo * This stores cwq for the moment, for the timer_fn. 11167a22ad75STejun Heo * Note that the work's gcwq is preserved to allow 11177a22ad75STejun Heo * reentrance detection for delayed works. 11187a22ad75STejun Heo */ 1119c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1120c7fc77f7STejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 1121c7fc77f7STejun Heo 1122c7fc77f7STejun Heo if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) 1123c7fc77f7STejun Heo lcpu = gcwq->cpu; 1124c7fc77f7STejun Heo else 1125c7fc77f7STejun Heo lcpu = raw_smp_processor_id(); 1126c7fc77f7STejun Heo } else 1127c7fc77f7STejun Heo lcpu = WORK_CPU_UNBOUND; 1128c7fc77f7STejun Heo 11297a22ad75STejun Heo set_work_cwq(work, get_cwq(lcpu, wq), 0); 1130c7fc77f7STejun Heo 11317a6bc1cdSVenkatesh Pallipadi timer->expires = jiffies + delay; 113252bad64dSDavid Howells timer->data = (unsigned long)dwork; 11337a6bc1cdSVenkatesh Pallipadi timer->function = delayed_work_timer_fn; 113463bc0362SOleg Nesterov 113563bc0362SOleg Nesterov if (unlikely(cpu >= 0)) 11367a6bc1cdSVenkatesh Pallipadi add_timer_on(timer, cpu); 113763bc0362SOleg Nesterov else 113863bc0362SOleg Nesterov add_timer(timer); 11397a6bc1cdSVenkatesh Pallipadi ret = 1; 11407a6bc1cdSVenkatesh Pallipadi } 11417a6bc1cdSVenkatesh Pallipadi return ret; 11427a6bc1cdSVenkatesh Pallipadi } 1143ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 11441da177e4SLinus Torvalds 1145c8e55f36STejun Heo /** 1146c8e55f36STejun Heo * worker_enter_idle - enter idle state 1147c8e55f36STejun Heo * @worker: worker which is entering idle state 1148c8e55f36STejun Heo * 1149c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1150c8e55f36STejun Heo * necessary. 1151c8e55f36STejun Heo * 1152c8e55f36STejun Heo * LOCKING: 1153c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1154c8e55f36STejun Heo */ 1155c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 11561da177e4SLinus Torvalds { 1157c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1158c8e55f36STejun Heo 1159c8e55f36STejun Heo BUG_ON(worker->flags & WORKER_IDLE); 1160c8e55f36STejun Heo BUG_ON(!list_empty(&worker->entry) && 1161c8e55f36STejun Heo (worker->hentry.next || worker->hentry.pprev)); 1162c8e55f36STejun Heo 1163cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1164cb444766STejun Heo worker->flags |= WORKER_IDLE; 1165c8e55f36STejun Heo gcwq->nr_idle++; 1166e22bee78STejun Heo worker->last_active = jiffies; 1167c8e55f36STejun Heo 1168c8e55f36STejun Heo /* idle_list is LIFO */ 1169c8e55f36STejun Heo list_add(&worker->entry, &gcwq->idle_list); 1170db7bccf4STejun Heo 1171e22bee78STejun Heo if (likely(!(worker->flags & WORKER_ROGUE))) { 1172e22bee78STejun Heo if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) 1173e22bee78STejun Heo mod_timer(&gcwq->idle_timer, 1174e22bee78STejun Heo jiffies + IDLE_WORKER_TIMEOUT); 1175e22bee78STejun Heo } else 1176db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 1177cb444766STejun Heo 1178cb444766STejun Heo /* sanity check nr_running */ 1179cb444766STejun Heo WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && 1180cb444766STejun Heo atomic_read(get_gcwq_nr_running(gcwq->cpu))); 1181c8e55f36STejun Heo } 1182c8e55f36STejun Heo 1183c8e55f36STejun Heo /** 1184c8e55f36STejun Heo * worker_leave_idle - leave idle state 1185c8e55f36STejun Heo * @worker: worker which is leaving idle state 1186c8e55f36STejun Heo * 1187c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1188c8e55f36STejun Heo * 1189c8e55f36STejun Heo * LOCKING: 1190c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1191c8e55f36STejun Heo */ 1192c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1193c8e55f36STejun Heo { 1194c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1195c8e55f36STejun Heo 1196c8e55f36STejun Heo BUG_ON(!(worker->flags & WORKER_IDLE)); 1197d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1198c8e55f36STejun Heo gcwq->nr_idle--; 1199c8e55f36STejun Heo list_del_init(&worker->entry); 1200c8e55f36STejun Heo } 1201c8e55f36STejun Heo 1202e22bee78STejun Heo /** 1203e22bee78STejun Heo * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq 1204e22bee78STejun Heo * @worker: self 1205e22bee78STejun Heo * 1206e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1207e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1208e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1209e22bee78STejun Heo * guaranteed to execute on the cpu. 1210e22bee78STejun Heo * 1211e22bee78STejun Heo * This function is to be used by rogue workers and rescuers to bind 1212e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1213e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1214e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1215e22bee78STejun Heo * verbatim as it's best effort and blocking and gcwq may be 1216e22bee78STejun Heo * [dis]associated in the meantime. 1217e22bee78STejun Heo * 1218e22bee78STejun Heo * This function tries set_cpus_allowed() and locks gcwq and verifies 1219e22bee78STejun Heo * the binding against GCWQ_DISASSOCIATED which is set during 1220e22bee78STejun Heo * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters 1221e22bee78STejun Heo * idle state or fetches works without dropping lock, it can guarantee 1222e22bee78STejun Heo * the scheduling requirement described in the first paragraph. 1223e22bee78STejun Heo * 1224e22bee78STejun Heo * CONTEXT: 1225e22bee78STejun Heo * Might sleep. Called without any lock but returns with gcwq->lock 1226e22bee78STejun Heo * held. 1227e22bee78STejun Heo * 1228e22bee78STejun Heo * RETURNS: 1229e22bee78STejun Heo * %true if the associated gcwq is online (@worker is successfully 1230e22bee78STejun Heo * bound), %false if offline. 1231e22bee78STejun Heo */ 1232e22bee78STejun Heo static bool worker_maybe_bind_and_lock(struct worker *worker) 1233972fa1c5SNamhyung Kim __acquires(&gcwq->lock) 1234e22bee78STejun Heo { 1235e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1236e22bee78STejun Heo struct task_struct *task = worker->task; 1237e22bee78STejun Heo 1238e22bee78STejun Heo while (true) { 1239e22bee78STejun Heo /* 1240e22bee78STejun Heo * The following call may fail, succeed or succeed 1241e22bee78STejun Heo * without actually migrating the task to the cpu if 1242e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 1243e22bee78STejun Heo * against GCWQ_DISASSOCIATED. 1244e22bee78STejun Heo */ 1245f3421797STejun Heo if (!(gcwq->flags & GCWQ_DISASSOCIATED)) 1246e22bee78STejun Heo set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); 1247e22bee78STejun Heo 1248e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1249e22bee78STejun Heo if (gcwq->flags & GCWQ_DISASSOCIATED) 1250e22bee78STejun Heo return false; 1251e22bee78STejun Heo if (task_cpu(task) == gcwq->cpu && 1252e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1253e22bee78STejun Heo get_cpu_mask(gcwq->cpu))) 1254e22bee78STejun Heo return true; 1255e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1256e22bee78STejun Heo 1257e22bee78STejun Heo /* CPU has come up inbetween, retry migration */ 1258e22bee78STejun Heo cpu_relax(); 1259e22bee78STejun Heo } 1260e22bee78STejun Heo } 1261e22bee78STejun Heo 1262e22bee78STejun Heo /* 1263e22bee78STejun Heo * Function for worker->rebind_work used to rebind rogue busy workers 1264e22bee78STejun Heo * to the associated cpu which is coming back online. This is 1265e22bee78STejun Heo * scheduled by cpu up but can race with other cpu hotplug operations 1266e22bee78STejun Heo * and may be executed twice without intervening cpu down. 1267e22bee78STejun Heo */ 1268e22bee78STejun Heo static void worker_rebind_fn(struct work_struct *work) 1269e22bee78STejun Heo { 1270e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1271e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1272e22bee78STejun Heo 1273e22bee78STejun Heo if (worker_maybe_bind_and_lock(worker)) 1274e22bee78STejun Heo worker_clr_flags(worker, WORKER_REBIND); 1275e22bee78STejun Heo 1276e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1277e22bee78STejun Heo } 1278e22bee78STejun Heo 1279c34056a3STejun Heo static struct worker *alloc_worker(void) 1280c34056a3STejun Heo { 1281c34056a3STejun Heo struct worker *worker; 1282c34056a3STejun Heo 1283c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1284c8e55f36STejun Heo if (worker) { 1285c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1286affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1287e22bee78STejun Heo INIT_WORK(&worker->rebind_work, worker_rebind_fn); 1288e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1289e22bee78STejun Heo worker->flags = WORKER_PREP; 1290c8e55f36STejun Heo } 1291c34056a3STejun Heo return worker; 1292c34056a3STejun Heo } 1293c34056a3STejun Heo 1294c34056a3STejun Heo /** 1295c34056a3STejun Heo * create_worker - create a new workqueue worker 12967e11629dSTejun Heo * @gcwq: gcwq the new worker will belong to 1297c34056a3STejun Heo * @bind: whether to set affinity to @cpu or not 1298c34056a3STejun Heo * 12997e11629dSTejun Heo * Create a new worker which is bound to @gcwq. The returned worker 1300c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1301c34056a3STejun Heo * destroy_worker(). 1302c34056a3STejun Heo * 1303c34056a3STejun Heo * CONTEXT: 1304c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1305c34056a3STejun Heo * 1306c34056a3STejun Heo * RETURNS: 1307c34056a3STejun Heo * Pointer to the newly created worker. 1308c34056a3STejun Heo */ 13097e11629dSTejun Heo static struct worker *create_worker(struct global_cwq *gcwq, bool bind) 1310c34056a3STejun Heo { 1311f3421797STejun Heo bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; 1312c34056a3STejun Heo struct worker *worker = NULL; 1313f3421797STejun Heo int id = -1; 1314c34056a3STejun Heo 13158b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13168b03ae3cSTejun Heo while (ida_get_new(&gcwq->worker_ida, &id)) { 13178b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 13188b03ae3cSTejun Heo if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) 1319c34056a3STejun Heo goto fail; 13208b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1321c34056a3STejun Heo } 13228b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1323c34056a3STejun Heo 1324c34056a3STejun Heo worker = alloc_worker(); 1325c34056a3STejun Heo if (!worker) 1326c34056a3STejun Heo goto fail; 1327c34056a3STejun Heo 13288b03ae3cSTejun Heo worker->gcwq = gcwq; 1329c34056a3STejun Heo worker->id = id; 1330c34056a3STejun Heo 1331f3421797STejun Heo if (!on_unbound_cpu) 1332f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1333f3421797STejun Heo "kworker/%u:%d", gcwq->cpu, id); 1334f3421797STejun Heo else 1335f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1336f3421797STejun Heo "kworker/u:%d", id); 1337c34056a3STejun Heo if (IS_ERR(worker->task)) 1338c34056a3STejun Heo goto fail; 1339c34056a3STejun Heo 1340db7bccf4STejun Heo /* 1341db7bccf4STejun Heo * A rogue worker will become a regular one if CPU comes 1342db7bccf4STejun Heo * online later on. Make sure every worker has 1343db7bccf4STejun Heo * PF_THREAD_BOUND set. 1344db7bccf4STejun Heo */ 1345f3421797STejun Heo if (bind && !on_unbound_cpu) 13468b03ae3cSTejun Heo kthread_bind(worker->task, gcwq->cpu); 1347f3421797STejun Heo else { 1348db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1349f3421797STejun Heo if (on_unbound_cpu) 1350f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1351f3421797STejun Heo } 1352c34056a3STejun Heo 1353c34056a3STejun Heo return worker; 1354c34056a3STejun Heo fail: 1355c34056a3STejun Heo if (id >= 0) { 13568b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13578b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 13588b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1359c34056a3STejun Heo } 1360c34056a3STejun Heo kfree(worker); 1361c34056a3STejun Heo return NULL; 1362c34056a3STejun Heo } 1363c34056a3STejun Heo 1364c34056a3STejun Heo /** 1365c34056a3STejun Heo * start_worker - start a newly created worker 1366c34056a3STejun Heo * @worker: worker to start 1367c34056a3STejun Heo * 1368c8e55f36STejun Heo * Make the gcwq aware of @worker and start it. 1369c34056a3STejun Heo * 1370c34056a3STejun Heo * CONTEXT: 13718b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1372c34056a3STejun Heo */ 1373c34056a3STejun Heo static void start_worker(struct worker *worker) 1374c34056a3STejun Heo { 1375cb444766STejun Heo worker->flags |= WORKER_STARTED; 1376c8e55f36STejun Heo worker->gcwq->nr_workers++; 1377c8e55f36STejun Heo worker_enter_idle(worker); 1378c34056a3STejun Heo wake_up_process(worker->task); 1379c34056a3STejun Heo } 1380c34056a3STejun Heo 1381c34056a3STejun Heo /** 1382c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1383c34056a3STejun Heo * @worker: worker to be destroyed 1384c34056a3STejun Heo * 1385c8e55f36STejun Heo * Destroy @worker and adjust @gcwq stats accordingly. 1386c8e55f36STejun Heo * 1387c8e55f36STejun Heo * CONTEXT: 1388c8e55f36STejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1389c34056a3STejun Heo */ 1390c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1391c34056a3STejun Heo { 13928b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 1393c34056a3STejun Heo int id = worker->id; 1394c34056a3STejun Heo 1395c34056a3STejun Heo /* sanity check frenzy */ 1396c34056a3STejun Heo BUG_ON(worker->current_work); 1397affee4b2STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1398c34056a3STejun Heo 1399c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1400c8e55f36STejun Heo gcwq->nr_workers--; 1401c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1402c8e55f36STejun Heo gcwq->nr_idle--; 1403c8e55f36STejun Heo 1404c8e55f36STejun Heo list_del_init(&worker->entry); 1405cb444766STejun Heo worker->flags |= WORKER_DIE; 1406c8e55f36STejun Heo 1407c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1408c8e55f36STejun Heo 1409c34056a3STejun Heo kthread_stop(worker->task); 1410c34056a3STejun Heo kfree(worker); 1411c34056a3STejun Heo 14128b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 14138b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 1414c34056a3STejun Heo } 1415c34056a3STejun Heo 1416e22bee78STejun Heo static void idle_worker_timeout(unsigned long __gcwq) 1417e22bee78STejun Heo { 1418e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1419e22bee78STejun Heo 1420e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1421e22bee78STejun Heo 1422e22bee78STejun Heo if (too_many_workers(gcwq)) { 1423e22bee78STejun Heo struct worker *worker; 1424e22bee78STejun Heo unsigned long expires; 1425e22bee78STejun Heo 1426e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 1427e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1428e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1429e22bee78STejun Heo 1430e22bee78STejun Heo if (time_before(jiffies, expires)) 1431e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1432e22bee78STejun Heo else { 1433e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 1434e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 1435e22bee78STejun Heo wake_up_worker(gcwq); 1436e22bee78STejun Heo } 1437e22bee78STejun Heo } 1438e22bee78STejun Heo 1439e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1440e22bee78STejun Heo } 1441e22bee78STejun Heo 1442e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1443e22bee78STejun Heo { 1444e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1445e22bee78STejun Heo struct workqueue_struct *wq = cwq->wq; 1446f3421797STejun Heo unsigned int cpu; 1447e22bee78STejun Heo 1448e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1449e22bee78STejun Heo return false; 1450e22bee78STejun Heo 1451e22bee78STejun Heo /* mayday mayday mayday */ 1452f3421797STejun Heo cpu = cwq->gcwq->cpu; 1453f3421797STejun Heo /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1454f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 1455f3421797STejun Heo cpu = 0; 1456f2e005aaSTejun Heo if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) 1457e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1458e22bee78STejun Heo return true; 1459e22bee78STejun Heo } 1460e22bee78STejun Heo 1461e22bee78STejun Heo static void gcwq_mayday_timeout(unsigned long __gcwq) 1462e22bee78STejun Heo { 1463e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1464e22bee78STejun Heo struct work_struct *work; 1465e22bee78STejun Heo 1466e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1467e22bee78STejun Heo 1468e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 1469e22bee78STejun Heo /* 1470e22bee78STejun Heo * We've been trying to create a new worker but 1471e22bee78STejun Heo * haven't been successful. We might be hitting an 1472e22bee78STejun Heo * allocation deadlock. Send distress signals to 1473e22bee78STejun Heo * rescuers. 1474e22bee78STejun Heo */ 1475e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) 1476e22bee78STejun Heo send_mayday(work); 1477e22bee78STejun Heo } 1478e22bee78STejun Heo 1479e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1480e22bee78STejun Heo 1481e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); 1482e22bee78STejun Heo } 1483e22bee78STejun Heo 1484e22bee78STejun Heo /** 1485e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 1486e22bee78STejun Heo * @gcwq: gcwq to create a new worker for 1487e22bee78STejun Heo * 1488e22bee78STejun Heo * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to 1489e22bee78STejun Heo * have at least one idle worker on return from this function. If 1490e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 1491e22bee78STejun Heo * sent to all rescuers with works scheduled on @gcwq to resolve 1492e22bee78STejun Heo * possible allocation deadlock. 1493e22bee78STejun Heo * 1494e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1495e22bee78STejun Heo * may_start_working() true. 1496e22bee78STejun Heo * 1497e22bee78STejun Heo * LOCKING: 1498e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1499e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1500e22bee78STejun Heo * manager. 1501e22bee78STejun Heo * 1502e22bee78STejun Heo * RETURNS: 1503e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1504e22bee78STejun Heo * otherwise. 1505e22bee78STejun Heo */ 1506e22bee78STejun Heo static bool maybe_create_worker(struct global_cwq *gcwq) 150706bd6ebfSNamhyung Kim __releases(&gcwq->lock) 150806bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 1509e22bee78STejun Heo { 1510e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1511e22bee78STejun Heo return false; 1512e22bee78STejun Heo restart: 15139f9c2364STejun Heo spin_unlock_irq(&gcwq->lock); 15149f9c2364STejun Heo 1515e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 1516e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1517e22bee78STejun Heo 1518e22bee78STejun Heo while (true) { 1519e22bee78STejun Heo struct worker *worker; 1520e22bee78STejun Heo 1521e22bee78STejun Heo worker = create_worker(gcwq, true); 1522e22bee78STejun Heo if (worker) { 1523e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1524e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1525e22bee78STejun Heo start_worker(worker); 1526e22bee78STejun Heo BUG_ON(need_to_create_worker(gcwq)); 1527e22bee78STejun Heo return true; 1528e22bee78STejun Heo } 1529e22bee78STejun Heo 1530e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1531e22bee78STejun Heo break; 1532e22bee78STejun Heo 1533e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1534e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 15359f9c2364STejun Heo 1536e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1537e22bee78STejun Heo break; 1538e22bee78STejun Heo } 1539e22bee78STejun Heo 1540e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1541e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1542e22bee78STejun Heo if (need_to_create_worker(gcwq)) 1543e22bee78STejun Heo goto restart; 1544e22bee78STejun Heo return true; 1545e22bee78STejun Heo } 1546e22bee78STejun Heo 1547e22bee78STejun Heo /** 1548e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 1549e22bee78STejun Heo * @gcwq: gcwq to destroy workers for 1550e22bee78STejun Heo * 1551e22bee78STejun Heo * Destroy @gcwq workers which have been idle for longer than 1552e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1553e22bee78STejun Heo * 1554e22bee78STejun Heo * LOCKING: 1555e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1556e22bee78STejun Heo * multiple times. Called only from manager. 1557e22bee78STejun Heo * 1558e22bee78STejun Heo * RETURNS: 1559e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1560e22bee78STejun Heo * otherwise. 1561e22bee78STejun Heo */ 1562e22bee78STejun Heo static bool maybe_destroy_workers(struct global_cwq *gcwq) 1563e22bee78STejun Heo { 1564e22bee78STejun Heo bool ret = false; 1565e22bee78STejun Heo 1566e22bee78STejun Heo while (too_many_workers(gcwq)) { 1567e22bee78STejun Heo struct worker *worker; 1568e22bee78STejun Heo unsigned long expires; 1569e22bee78STejun Heo 1570e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1571e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1572e22bee78STejun Heo 1573e22bee78STejun Heo if (time_before(jiffies, expires)) { 1574e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1575e22bee78STejun Heo break; 1576e22bee78STejun Heo } 1577e22bee78STejun Heo 1578e22bee78STejun Heo destroy_worker(worker); 1579e22bee78STejun Heo ret = true; 1580e22bee78STejun Heo } 1581e22bee78STejun Heo 1582e22bee78STejun Heo return ret; 1583e22bee78STejun Heo } 1584e22bee78STejun Heo 1585e22bee78STejun Heo /** 1586e22bee78STejun Heo * manage_workers - manage worker pool 1587e22bee78STejun Heo * @worker: self 1588e22bee78STejun Heo * 1589e22bee78STejun Heo * Assume the manager role and manage gcwq worker pool @worker belongs 1590e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 1591e22bee78STejun Heo * gcwq. The exclusion is handled automatically by this function. 1592e22bee78STejun Heo * 1593e22bee78STejun Heo * The caller can safely start processing works on false return. On 1594e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 1595e22bee78STejun Heo * and may_start_working() is true. 1596e22bee78STejun Heo * 1597e22bee78STejun Heo * CONTEXT: 1598e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1599e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 1600e22bee78STejun Heo * 1601e22bee78STejun Heo * RETURNS: 1602e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true if 1603e22bee78STejun Heo * some action was taken. 1604e22bee78STejun Heo */ 1605e22bee78STejun Heo static bool manage_workers(struct worker *worker) 1606e22bee78STejun Heo { 1607e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1608e22bee78STejun Heo bool ret = false; 1609e22bee78STejun Heo 1610e22bee78STejun Heo if (gcwq->flags & GCWQ_MANAGING_WORKERS) 1611e22bee78STejun Heo return ret; 1612e22bee78STejun Heo 1613e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGE_WORKERS; 1614e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 1615e22bee78STejun Heo 1616e22bee78STejun Heo /* 1617e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 1618e22bee78STejun Heo * on return. 1619e22bee78STejun Heo */ 1620e22bee78STejun Heo ret |= maybe_destroy_workers(gcwq); 1621e22bee78STejun Heo ret |= maybe_create_worker(gcwq); 1622e22bee78STejun Heo 1623e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 1624e22bee78STejun Heo 1625e22bee78STejun Heo /* 1626e22bee78STejun Heo * The trustee might be waiting to take over the manager 1627e22bee78STejun Heo * position, tell it we're done. 1628e22bee78STejun Heo */ 1629e22bee78STejun Heo if (unlikely(gcwq->trustee)) 1630e22bee78STejun Heo wake_up_all(&gcwq->trustee_wait); 1631e22bee78STejun Heo 1632e22bee78STejun Heo return ret; 1633e22bee78STejun Heo } 1634e22bee78STejun Heo 1635a62428c0STejun Heo /** 1636affee4b2STejun Heo * move_linked_works - move linked works to a list 1637affee4b2STejun Heo * @work: start of series of works to be scheduled 1638affee4b2STejun Heo * @head: target list to append @work to 1639affee4b2STejun Heo * @nextp: out paramter for nested worklist walking 1640affee4b2STejun Heo * 1641affee4b2STejun Heo * Schedule linked works starting from @work to @head. Work series to 1642affee4b2STejun Heo * be scheduled starts at @work and includes any consecutive work with 1643affee4b2STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 1644affee4b2STejun Heo * 1645affee4b2STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 1646affee4b2STejun Heo * the last scheduled work. This allows move_linked_works() to be 1647affee4b2STejun Heo * nested inside outer list_for_each_entry_safe(). 1648affee4b2STejun Heo * 1649affee4b2STejun Heo * CONTEXT: 16508b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1651affee4b2STejun Heo */ 1652affee4b2STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1653affee4b2STejun Heo struct work_struct **nextp) 1654affee4b2STejun Heo { 1655affee4b2STejun Heo struct work_struct *n; 1656affee4b2STejun Heo 1657affee4b2STejun Heo /* 1658affee4b2STejun Heo * Linked worklist will always end before the end of the list, 1659affee4b2STejun Heo * use NULL for list head. 1660affee4b2STejun Heo */ 1661affee4b2STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1662affee4b2STejun Heo list_move_tail(&work->entry, head); 1663affee4b2STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1664affee4b2STejun Heo break; 1665affee4b2STejun Heo } 1666affee4b2STejun Heo 1667affee4b2STejun Heo /* 1668affee4b2STejun Heo * If we're already inside safe list traversal and have moved 1669affee4b2STejun Heo * multiple works to the scheduled queue, the next position 1670affee4b2STejun Heo * needs to be updated. 1671affee4b2STejun Heo */ 1672affee4b2STejun Heo if (nextp) 1673affee4b2STejun Heo *nextp = n; 1674affee4b2STejun Heo } 1675affee4b2STejun Heo 16761e19ffc6STejun Heo static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) 16771e19ffc6STejun Heo { 16781e19ffc6STejun Heo struct work_struct *work = list_first_entry(&cwq->delayed_works, 16791da177e4SLinus Torvalds struct work_struct, entry); 1680649027d7STejun Heo struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); 16811e19ffc6STejun Heo 1682649027d7STejun Heo move_linked_works(work, pos, NULL); 16838a2e8e5dSTejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 16841e19ffc6STejun Heo cwq->nr_active++; 16851e19ffc6STejun Heo } 16861e19ffc6STejun Heo 1687affee4b2STejun Heo /** 168873f53c4aSTejun Heo * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight 168973f53c4aSTejun Heo * @cwq: cwq of interest 169073f53c4aSTejun Heo * @color: color of work which left the queue 16918a2e8e5dSTejun Heo * @delayed: for a delayed work 169273f53c4aSTejun Heo * 169373f53c4aSTejun Heo * A work either has completed or is removed from pending queue, 169473f53c4aSTejun Heo * decrement nr_in_flight of its cwq and handle workqueue flushing. 169573f53c4aSTejun Heo * 169673f53c4aSTejun Heo * CONTEXT: 16978b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 169873f53c4aSTejun Heo */ 16998a2e8e5dSTejun Heo static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, 17008a2e8e5dSTejun Heo bool delayed) 170173f53c4aSTejun Heo { 170273f53c4aSTejun Heo /* ignore uncolored works */ 170373f53c4aSTejun Heo if (color == WORK_NO_COLOR) 170473f53c4aSTejun Heo return; 170573f53c4aSTejun Heo 170673f53c4aSTejun Heo cwq->nr_in_flight[color]--; 17071e19ffc6STejun Heo 17088a2e8e5dSTejun Heo if (!delayed) { 17098a2e8e5dSTejun Heo cwq->nr_active--; 1710502ca9d8STejun Heo if (!list_empty(&cwq->delayed_works)) { 17111e19ffc6STejun Heo /* one down, submit a delayed one */ 1712502ca9d8STejun Heo if (cwq->nr_active < cwq->max_active) 17131e19ffc6STejun Heo cwq_activate_first_delayed(cwq); 1714502ca9d8STejun Heo } 17158a2e8e5dSTejun Heo } 171673f53c4aSTejun Heo 171773f53c4aSTejun Heo /* is flush in progress and are we at the flushing tip? */ 171873f53c4aSTejun Heo if (likely(cwq->flush_color != color)) 171973f53c4aSTejun Heo return; 172073f53c4aSTejun Heo 172173f53c4aSTejun Heo /* are there still in-flight works? */ 172273f53c4aSTejun Heo if (cwq->nr_in_flight[color]) 172373f53c4aSTejun Heo return; 172473f53c4aSTejun Heo 172573f53c4aSTejun Heo /* this cwq is done, clear flush_color */ 172673f53c4aSTejun Heo cwq->flush_color = -1; 172773f53c4aSTejun Heo 172873f53c4aSTejun Heo /* 172973f53c4aSTejun Heo * If this was the last cwq, wake up the first flusher. It 173073f53c4aSTejun Heo * will handle the rest. 173173f53c4aSTejun Heo */ 173273f53c4aSTejun Heo if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) 173373f53c4aSTejun Heo complete(&cwq->wq->first_flusher->done); 173473f53c4aSTejun Heo } 173573f53c4aSTejun Heo 173673f53c4aSTejun Heo /** 1737a62428c0STejun Heo * process_one_work - process single work 1738c34056a3STejun Heo * @worker: self 1739a62428c0STejun Heo * @work: work to process 1740a62428c0STejun Heo * 1741a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 1742a62428c0STejun Heo * process a single work including synchronization against and 1743a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 1744a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 1745a62428c0STejun Heo * call this function to process a work. 1746a62428c0STejun Heo * 1747a62428c0STejun Heo * CONTEXT: 17488b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1749a62428c0STejun Heo */ 1750c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 175106bd6ebfSNamhyung Kim __releases(&gcwq->lock) 175206bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 17531da177e4SLinus Torvalds { 17547e11629dSTejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 17558b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 1756c8e55f36STejun Heo struct hlist_head *bwh = busy_worker_head(gcwq, work); 1757fb0e7bebSTejun Heo bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 17586bb49e59SDavid Howells work_func_t f = work->func; 175973f53c4aSTejun Heo int work_color; 17607e11629dSTejun Heo struct worker *collision; 17614e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 17624e6045f1SJohannes Berg /* 1763a62428c0STejun Heo * It is permissible to free the struct work_struct from 1764a62428c0STejun Heo * inside the function that is called from it, this we need to 1765a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 1766a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 1767a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 17684e6045f1SJohannes Berg */ 17694e6045f1SJohannes Berg struct lockdep_map lockdep_map = work->lockdep_map; 17704e6045f1SJohannes Berg #endif 17717e11629dSTejun Heo /* 17727e11629dSTejun Heo * A single work shouldn't be executed concurrently by 17737e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 17747e11629dSTejun Heo * already processing the work. If so, defer the work to the 17757e11629dSTejun Heo * currently executing one. 17767e11629dSTejun Heo */ 17777e11629dSTejun Heo collision = __find_worker_executing_work(gcwq, bwh, work); 17787e11629dSTejun Heo if (unlikely(collision)) { 17797e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 17807e11629dSTejun Heo return; 17817e11629dSTejun Heo } 17821da177e4SLinus Torvalds 1783a62428c0STejun Heo /* claim and process */ 17841da177e4SLinus Torvalds debug_work_deactivate(work); 1785c8e55f36STejun Heo hlist_add_head(&worker->hentry, bwh); 1786c34056a3STejun Heo worker->current_work = work; 17878cca0eeaSTejun Heo worker->current_cwq = cwq; 178873f53c4aSTejun Heo work_color = get_work_color(work); 17897a22ad75STejun Heo 17907a22ad75STejun Heo /* record the current cpu number in the work data and dequeue */ 17917a22ad75STejun Heo set_work_cpu(work, gcwq->cpu); 1792a62428c0STejun Heo list_del_init(&work->entry); 1793a62428c0STejun Heo 1794649027d7STejun Heo /* 1795649027d7STejun Heo * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, 1796649027d7STejun Heo * wake up another worker; otherwise, clear HIGHPRI_PENDING. 1797649027d7STejun Heo */ 1798649027d7STejun Heo if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { 1799649027d7STejun Heo struct work_struct *nwork = list_first_entry(&gcwq->worklist, 1800649027d7STejun Heo struct work_struct, entry); 1801649027d7STejun Heo 1802649027d7STejun Heo if (!list_empty(&gcwq->worklist) && 1803649027d7STejun Heo get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) 1804649027d7STejun Heo wake_up_worker(gcwq); 1805649027d7STejun Heo else 1806649027d7STejun Heo gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; 1807649027d7STejun Heo } 1808649027d7STejun Heo 1809fb0e7bebSTejun Heo /* 1810fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 1811fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 1812fb0e7bebSTejun Heo */ 1813fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1814fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 1815fb0e7bebSTejun Heo 18168b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 18171da177e4SLinus Torvalds 181823b2e599SOleg Nesterov work_clear_pending(work); 18193295f0efSIngo Molnar lock_map_acquire(&cwq->wq->lockdep_map); 18203295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 1821e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 182265f27f38SDavid Howells f(work); 1823e36c886aSArjan van de Ven /* 1824e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 1825e36c886aSArjan van de Ven * point will only record its address. 1826e36c886aSArjan van de Ven */ 1827e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 18283295f0efSIngo Molnar lock_map_release(&lockdep_map); 18293295f0efSIngo Molnar lock_map_release(&cwq->wq->lockdep_map); 18301da177e4SLinus Torvalds 1831d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 1832d5abe669SPeter Zijlstra printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " 1833d5abe669SPeter Zijlstra "%s/0x%08x/%d\n", 1834a62428c0STejun Heo current->comm, preempt_count(), task_pid_nr(current)); 1835d5abe669SPeter Zijlstra printk(KERN_ERR " last function: "); 1836d5abe669SPeter Zijlstra print_symbol("%s\n", (unsigned long)f); 1837d5abe669SPeter Zijlstra debug_show_held_locks(current); 1838d5abe669SPeter Zijlstra dump_stack(); 1839d5abe669SPeter Zijlstra } 1840d5abe669SPeter Zijlstra 18418b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1842a62428c0STejun Heo 1843fb0e7bebSTejun Heo /* clear cpu intensive status */ 1844fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1845fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 1846fb0e7bebSTejun Heo 1847a62428c0STejun Heo /* we're done with it, release */ 1848c8e55f36STejun Heo hlist_del_init(&worker->hentry); 1849c34056a3STejun Heo worker->current_work = NULL; 18508cca0eeaSTejun Heo worker->current_cwq = NULL; 18518a2e8e5dSTejun Heo cwq_dec_nr_in_flight(cwq, work_color, false); 18521da177e4SLinus Torvalds } 18531da177e4SLinus Torvalds 1854affee4b2STejun Heo /** 1855affee4b2STejun Heo * process_scheduled_works - process scheduled works 1856affee4b2STejun Heo * @worker: self 1857affee4b2STejun Heo * 1858affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 1859affee4b2STejun Heo * may change while processing a work, so this function repeatedly 1860affee4b2STejun Heo * fetches a work from the top and executes it. 1861affee4b2STejun Heo * 1862affee4b2STejun Heo * CONTEXT: 18638b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1864affee4b2STejun Heo * multiple times. 1865affee4b2STejun Heo */ 1866affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 18671da177e4SLinus Torvalds { 1868affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 1869affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 1870a62428c0STejun Heo struct work_struct, entry); 1871c34056a3STejun Heo process_one_work(worker, work); 1872a62428c0STejun Heo } 18731da177e4SLinus Torvalds } 18741da177e4SLinus Torvalds 18754690c4abSTejun Heo /** 18764690c4abSTejun Heo * worker_thread - the worker thread function 1877c34056a3STejun Heo * @__worker: self 18784690c4abSTejun Heo * 1879e22bee78STejun Heo * The gcwq worker thread function. There's a single dynamic pool of 1880e22bee78STejun Heo * these per each cpu. These workers process all works regardless of 1881e22bee78STejun Heo * their specific target workqueue. The only exception is works which 1882e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 1883e22bee78STejun Heo * rescuer_thread(). 18844690c4abSTejun Heo */ 1885c34056a3STejun Heo static int worker_thread(void *__worker) 18861da177e4SLinus Torvalds { 1887c34056a3STejun Heo struct worker *worker = __worker; 18888b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 18891da177e4SLinus Torvalds 1890e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 1891e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 1892c8e55f36STejun Heo woke_up: 18938b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1894affee4b2STejun Heo 1895c8e55f36STejun Heo /* DIE can be set only while we're idle, checking here is enough */ 1896c8e55f36STejun Heo if (worker->flags & WORKER_DIE) { 1897c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1898e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 1899c8e55f36STejun Heo return 0; 1900c8e55f36STejun Heo } 1901c8e55f36STejun Heo 1902c8e55f36STejun Heo worker_leave_idle(worker); 1903db7bccf4STejun Heo recheck: 1904e22bee78STejun Heo /* no more worker necessary? */ 1905e22bee78STejun Heo if (!need_more_worker(gcwq)) 1906e22bee78STejun Heo goto sleep; 1907e22bee78STejun Heo 1908e22bee78STejun Heo /* do we need to manage? */ 1909e22bee78STejun Heo if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) 1910e22bee78STejun Heo goto recheck; 1911e22bee78STejun Heo 1912c8e55f36STejun Heo /* 1913c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 1914c8e55f36STejun Heo * preparing to process a work or actually processing it. 1915c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 1916c8e55f36STejun Heo */ 1917c8e55f36STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1918c8e55f36STejun Heo 1919e22bee78STejun Heo /* 1920e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 1921e22bee78STejun Heo * at least one idle worker or that someone else has already 1922e22bee78STejun Heo * assumed the manager role. 1923e22bee78STejun Heo */ 1924e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 1925e22bee78STejun Heo 1926e22bee78STejun Heo do { 1927affee4b2STejun Heo struct work_struct *work = 19287e11629dSTejun Heo list_first_entry(&gcwq->worklist, 1929affee4b2STejun Heo struct work_struct, entry); 1930affee4b2STejun Heo 1931c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 1932affee4b2STejun Heo /* optimization path, not strictly necessary */ 1933affee4b2STejun Heo process_one_work(worker, work); 1934affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 1935affee4b2STejun Heo process_scheduled_works(worker); 1936affee4b2STejun Heo } else { 1937c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 1938affee4b2STejun Heo process_scheduled_works(worker); 1939affee4b2STejun Heo } 1940e22bee78STejun Heo } while (keep_working(gcwq)); 1941affee4b2STejun Heo 1942e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 1943d313dd85STejun Heo sleep: 1944e22bee78STejun Heo if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) 1945e22bee78STejun Heo goto recheck; 1946d313dd85STejun Heo 1947c8e55f36STejun Heo /* 1948e22bee78STejun Heo * gcwq->lock is held and there's no work to process and no 1949e22bee78STejun Heo * need to manage, sleep. Workers are woken up only while 1950e22bee78STejun Heo * holding gcwq->lock or from local cpu, so setting the 1951e22bee78STejun Heo * current state before releasing gcwq->lock is enough to 1952e22bee78STejun Heo * prevent losing any event. 1953c8e55f36STejun Heo */ 1954c8e55f36STejun Heo worker_enter_idle(worker); 1955c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 19568b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 19571da177e4SLinus Torvalds schedule(); 1958c8e55f36STejun Heo goto woke_up; 19591da177e4SLinus Torvalds } 19601da177e4SLinus Torvalds 1961e22bee78STejun Heo /** 1962e22bee78STejun Heo * rescuer_thread - the rescuer thread function 1963e22bee78STejun Heo * @__wq: the associated workqueue 1964e22bee78STejun Heo * 1965e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 1966e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 1967e22bee78STejun Heo * 1968e22bee78STejun Heo * Regular work processing on a gcwq may block trying to create a new 1969e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 1970e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 1971e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 1972e22bee78STejun Heo * the problem rescuer solves. 1973e22bee78STejun Heo * 1974e22bee78STejun Heo * When such condition is possible, the gcwq summons rescuers of all 1975e22bee78STejun Heo * workqueues which have works queued on the gcwq and let them process 1976e22bee78STejun Heo * those works so that forward progress can be guaranteed. 1977e22bee78STejun Heo * 1978e22bee78STejun Heo * This should happen rarely. 1979e22bee78STejun Heo */ 1980e22bee78STejun Heo static int rescuer_thread(void *__wq) 1981e22bee78STejun Heo { 1982e22bee78STejun Heo struct workqueue_struct *wq = __wq; 1983e22bee78STejun Heo struct worker *rescuer = wq->rescuer; 1984e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 1985f3421797STejun Heo bool is_unbound = wq->flags & WQ_UNBOUND; 1986e22bee78STejun Heo unsigned int cpu; 1987e22bee78STejun Heo 1988e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 1989e22bee78STejun Heo repeat: 1990e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 19911da177e4SLinus Torvalds 19921da177e4SLinus Torvalds if (kthread_should_stop()) 1993e22bee78STejun Heo return 0; 19941da177e4SLinus Torvalds 1995f3421797STejun Heo /* 1996f3421797STejun Heo * See whether any cpu is asking for help. Unbounded 1997f3421797STejun Heo * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. 1998f3421797STejun Heo */ 1999f2e005aaSTejun Heo for_each_mayday_cpu(cpu, wq->mayday_mask) { 2000f3421797STejun Heo unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 2001f3421797STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); 2002e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 2003e22bee78STejun Heo struct work_struct *work, *n; 2004e22bee78STejun Heo 2005e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2006f2e005aaSTejun Heo mayday_clear_cpu(cpu, wq->mayday_mask); 2007e22bee78STejun Heo 2008e22bee78STejun Heo /* migrate to the target cpu if possible */ 2009e22bee78STejun Heo rescuer->gcwq = gcwq; 2010e22bee78STejun Heo worker_maybe_bind_and_lock(rescuer); 2011e22bee78STejun Heo 2012e22bee78STejun Heo /* 2013e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2014e22bee78STejun Heo * process'em. 2015e22bee78STejun Heo */ 2016e22bee78STejun Heo BUG_ON(!list_empty(&rescuer->scheduled)); 2017e22bee78STejun Heo list_for_each_entry_safe(work, n, &gcwq->worklist, entry) 2018e22bee78STejun Heo if (get_work_cwq(work) == cwq) 2019e22bee78STejun Heo move_linked_works(work, scheduled, &n); 2020e22bee78STejun Heo 2021e22bee78STejun Heo process_scheduled_works(rescuer); 2022e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 20231da177e4SLinus Torvalds } 20241da177e4SLinus Torvalds 2025e22bee78STejun Heo schedule(); 2026e22bee78STejun Heo goto repeat; 20271da177e4SLinus Torvalds } 20281da177e4SLinus Torvalds 2029fc2e4d70SOleg Nesterov struct wq_barrier { 2030fc2e4d70SOleg Nesterov struct work_struct work; 2031fc2e4d70SOleg Nesterov struct completion done; 2032fc2e4d70SOleg Nesterov }; 2033fc2e4d70SOleg Nesterov 2034fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2035fc2e4d70SOleg Nesterov { 2036fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2037fc2e4d70SOleg Nesterov complete(&barr->done); 2038fc2e4d70SOleg Nesterov } 2039fc2e4d70SOleg Nesterov 20404690c4abSTejun Heo /** 20414690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 20424690c4abSTejun Heo * @cwq: cwq to insert barrier into 20434690c4abSTejun Heo * @barr: wq_barrier to insert 2044affee4b2STejun Heo * @target: target work to attach @barr to 2045affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 20464690c4abSTejun Heo * 2047affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2048affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2049affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2050affee4b2STejun Heo * cpu. 2051affee4b2STejun Heo * 2052affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2053affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2054affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2055affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2056affee4b2STejun Heo * after a work with LINKED flag set. 2057affee4b2STejun Heo * 2058affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2059affee4b2STejun Heo * underneath us, so we can't reliably determine cwq from @target. 20604690c4abSTejun Heo * 20614690c4abSTejun Heo * CONTEXT: 20628b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 20634690c4abSTejun Heo */ 206483c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 2065affee4b2STejun Heo struct wq_barrier *barr, 2066affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2067fc2e4d70SOleg Nesterov { 2068affee4b2STejun Heo struct list_head *head; 2069affee4b2STejun Heo unsigned int linked = 0; 2070affee4b2STejun Heo 2071dc186ad7SThomas Gleixner /* 20728b03ae3cSTejun Heo * debugobject calls are safe here even with gcwq->lock locked 2073dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2074dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2075dc186ad7SThomas Gleixner * might deadlock. 2076dc186ad7SThomas Gleixner */ 2077dc186ad7SThomas Gleixner INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); 207822df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2079fc2e4d70SOleg Nesterov init_completion(&barr->done); 208083c22520SOleg Nesterov 2081affee4b2STejun Heo /* 2082affee4b2STejun Heo * If @target is currently being executed, schedule the 2083affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2084affee4b2STejun Heo */ 2085affee4b2STejun Heo if (worker) 2086affee4b2STejun Heo head = worker->scheduled.next; 2087affee4b2STejun Heo else { 2088affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2089affee4b2STejun Heo 2090affee4b2STejun Heo head = target->entry.next; 2091affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2092affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2093affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2094affee4b2STejun Heo } 2095affee4b2STejun Heo 2096dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2097affee4b2STejun Heo insert_work(cwq, &barr->work, head, 2098affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2099fc2e4d70SOleg Nesterov } 2100fc2e4d70SOleg Nesterov 210173f53c4aSTejun Heo /** 210273f53c4aSTejun Heo * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing 210373f53c4aSTejun Heo * @wq: workqueue being flushed 210473f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 210573f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 210673f53c4aSTejun Heo * 210773f53c4aSTejun Heo * Prepare cwqs for workqueue flushing. 210873f53c4aSTejun Heo * 210973f53c4aSTejun Heo * If @flush_color is non-negative, flush_color on all cwqs should be 211073f53c4aSTejun Heo * -1. If no cwq has in-flight commands at the specified color, all 211173f53c4aSTejun Heo * cwq->flush_color's stay at -1 and %false is returned. If any cwq 211273f53c4aSTejun Heo * has in flight commands, its cwq->flush_color is set to 211373f53c4aSTejun Heo * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq 211473f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 211573f53c4aSTejun Heo * 211673f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 211773f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 211873f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 211973f53c4aSTejun Heo * is returned. 212073f53c4aSTejun Heo * 212173f53c4aSTejun Heo * If @work_color is non-negative, all cwqs should have the same 212273f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 212373f53c4aSTejun Heo * advanced to @work_color. 212473f53c4aSTejun Heo * 212573f53c4aSTejun Heo * CONTEXT: 212673f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 212773f53c4aSTejun Heo * 212873f53c4aSTejun Heo * RETURNS: 212973f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 213073f53c4aSTejun Heo * otherwise. 213173f53c4aSTejun Heo */ 213273f53c4aSTejun Heo static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, 213373f53c4aSTejun Heo int flush_color, int work_color) 21341da177e4SLinus Torvalds { 213573f53c4aSTejun Heo bool wait = false; 213673f53c4aSTejun Heo unsigned int cpu; 21371da177e4SLinus Torvalds 213873f53c4aSTejun Heo if (flush_color >= 0) { 213973f53c4aSTejun Heo BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); 214073f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 1); 2141dc186ad7SThomas Gleixner } 214214441960SOleg Nesterov 2143f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 214473f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 21458b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 21461da177e4SLinus Torvalds 21478b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 214873f53c4aSTejun Heo 214973f53c4aSTejun Heo if (flush_color >= 0) { 215073f53c4aSTejun Heo BUG_ON(cwq->flush_color != -1); 215173f53c4aSTejun Heo 215273f53c4aSTejun Heo if (cwq->nr_in_flight[flush_color]) { 215373f53c4aSTejun Heo cwq->flush_color = flush_color; 215473f53c4aSTejun Heo atomic_inc(&wq->nr_cwqs_to_flush); 215573f53c4aSTejun Heo wait = true; 21561da177e4SLinus Torvalds } 215773f53c4aSTejun Heo } 215873f53c4aSTejun Heo 215973f53c4aSTejun Heo if (work_color >= 0) { 216073f53c4aSTejun Heo BUG_ON(work_color != work_next_color(cwq->work_color)); 216173f53c4aSTejun Heo cwq->work_color = work_color; 216273f53c4aSTejun Heo } 216373f53c4aSTejun Heo 21648b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 21651da177e4SLinus Torvalds } 21661da177e4SLinus Torvalds 216773f53c4aSTejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) 216873f53c4aSTejun Heo complete(&wq->first_flusher->done); 216973f53c4aSTejun Heo 217073f53c4aSTejun Heo return wait; 217183c22520SOleg Nesterov } 21721da177e4SLinus Torvalds 21730fcb78c2SRolf Eike Beer /** 21741da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 21750fcb78c2SRolf Eike Beer * @wq: workqueue to flush 21761da177e4SLinus Torvalds * 21771da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 21781da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 21791da177e4SLinus Torvalds * 2180fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2181fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 21821da177e4SLinus Torvalds */ 21837ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 21841da177e4SLinus Torvalds { 218573f53c4aSTejun Heo struct wq_flusher this_flusher = { 218673f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 218773f53c4aSTejun Heo .flush_color = -1, 218873f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 218973f53c4aSTejun Heo }; 219073f53c4aSTejun Heo int next_color; 2191b1f4ec17SOleg Nesterov 21923295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 21933295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 219473f53c4aSTejun Heo 219573f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 219673f53c4aSTejun Heo 219773f53c4aSTejun Heo /* 219873f53c4aSTejun Heo * Start-to-wait phase 219973f53c4aSTejun Heo */ 220073f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 220173f53c4aSTejun Heo 220273f53c4aSTejun Heo if (next_color != wq->flush_color) { 220373f53c4aSTejun Heo /* 220473f53c4aSTejun Heo * Color space is not full. The current work_color 220573f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 220673f53c4aSTejun Heo * by one. 220773f53c4aSTejun Heo */ 220873f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow)); 220973f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 221073f53c4aSTejun Heo wq->work_color = next_color; 221173f53c4aSTejun Heo 221273f53c4aSTejun Heo if (!wq->first_flusher) { 221373f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 221473f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 221573f53c4aSTejun Heo 221673f53c4aSTejun Heo wq->first_flusher = &this_flusher; 221773f53c4aSTejun Heo 221873f53c4aSTejun Heo if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, 221973f53c4aSTejun Heo wq->work_color)) { 222073f53c4aSTejun Heo /* nothing to flush, done */ 222173f53c4aSTejun Heo wq->flush_color = next_color; 222273f53c4aSTejun Heo wq->first_flusher = NULL; 222373f53c4aSTejun Heo goto out_unlock; 222473f53c4aSTejun Heo } 222573f53c4aSTejun Heo } else { 222673f53c4aSTejun Heo /* wait in queue */ 222773f53c4aSTejun Heo BUG_ON(wq->flush_color == this_flusher.flush_color); 222873f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 222973f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 223073f53c4aSTejun Heo } 223173f53c4aSTejun Heo } else { 223273f53c4aSTejun Heo /* 223373f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 223473f53c4aSTejun Heo * The next flush completion will assign us 223573f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 223673f53c4aSTejun Heo */ 223773f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 223873f53c4aSTejun Heo } 223973f53c4aSTejun Heo 224073f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 224173f53c4aSTejun Heo 224273f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 224373f53c4aSTejun Heo 224473f53c4aSTejun Heo /* 224573f53c4aSTejun Heo * Wake-up-and-cascade phase 224673f53c4aSTejun Heo * 224773f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 224873f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 224973f53c4aSTejun Heo */ 225073f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 225173f53c4aSTejun Heo return; 225273f53c4aSTejun Heo 225373f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 225473f53c4aSTejun Heo 22554ce48b37STejun Heo /* we might have raced, check again with mutex held */ 22564ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 22574ce48b37STejun Heo goto out_unlock; 22584ce48b37STejun Heo 225973f53c4aSTejun Heo wq->first_flusher = NULL; 226073f53c4aSTejun Heo 226173f53c4aSTejun Heo BUG_ON(!list_empty(&this_flusher.list)); 226273f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 226373f53c4aSTejun Heo 226473f53c4aSTejun Heo while (true) { 226573f53c4aSTejun Heo struct wq_flusher *next, *tmp; 226673f53c4aSTejun Heo 226773f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 226873f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 226973f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 227073f53c4aSTejun Heo break; 227173f53c4aSTejun Heo list_del_init(&next->list); 227273f53c4aSTejun Heo complete(&next->done); 227373f53c4aSTejun Heo } 227473f53c4aSTejun Heo 227573f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow) && 227673f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 227773f53c4aSTejun Heo 227873f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 227973f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 228073f53c4aSTejun Heo 228173f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 228273f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 228373f53c4aSTejun Heo /* 228473f53c4aSTejun Heo * Assign the same color to all overflowed 228573f53c4aSTejun Heo * flushers, advance work_color and append to 228673f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 228773f53c4aSTejun Heo * phase for these overflowed flushers. 228873f53c4aSTejun Heo */ 228973f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 229073f53c4aSTejun Heo tmp->flush_color = wq->work_color; 229173f53c4aSTejun Heo 229273f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 229373f53c4aSTejun Heo 229473f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 229573f53c4aSTejun Heo &wq->flusher_queue); 229673f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 229773f53c4aSTejun Heo } 229873f53c4aSTejun Heo 229973f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 230073f53c4aSTejun Heo BUG_ON(wq->flush_color != wq->work_color); 230173f53c4aSTejun Heo break; 230273f53c4aSTejun Heo } 230373f53c4aSTejun Heo 230473f53c4aSTejun Heo /* 230573f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 230673f53c4aSTejun Heo * the new first flusher and arm cwqs. 230773f53c4aSTejun Heo */ 230873f53c4aSTejun Heo BUG_ON(wq->flush_color == wq->work_color); 230973f53c4aSTejun Heo BUG_ON(wq->flush_color != next->flush_color); 231073f53c4aSTejun Heo 231173f53c4aSTejun Heo list_del_init(&next->list); 231273f53c4aSTejun Heo wq->first_flusher = next; 231373f53c4aSTejun Heo 231473f53c4aSTejun Heo if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) 231573f53c4aSTejun Heo break; 231673f53c4aSTejun Heo 231773f53c4aSTejun Heo /* 231873f53c4aSTejun Heo * Meh... this color is already done, clear first 231973f53c4aSTejun Heo * flusher and repeat cascading. 232073f53c4aSTejun Heo */ 232173f53c4aSTejun Heo wq->first_flusher = NULL; 232273f53c4aSTejun Heo } 232373f53c4aSTejun Heo 232473f53c4aSTejun Heo out_unlock: 232573f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 23261da177e4SLinus Torvalds } 2327ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 23281da177e4SLinus Torvalds 2329baf59022STejun Heo static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, 2330baf59022STejun Heo bool wait_executing) 2331baf59022STejun Heo { 2332baf59022STejun Heo struct worker *worker = NULL; 2333baf59022STejun Heo struct global_cwq *gcwq; 2334baf59022STejun Heo struct cpu_workqueue_struct *cwq; 2335baf59022STejun Heo 2336baf59022STejun Heo might_sleep(); 2337baf59022STejun Heo gcwq = get_work_gcwq(work); 2338baf59022STejun Heo if (!gcwq) 2339baf59022STejun Heo return false; 2340baf59022STejun Heo 2341baf59022STejun Heo spin_lock_irq(&gcwq->lock); 2342baf59022STejun Heo if (!list_empty(&work->entry)) { 2343baf59022STejun Heo /* 2344baf59022STejun Heo * See the comment near try_to_grab_pending()->smp_rmb(). 2345baf59022STejun Heo * If it was re-queued to a different gcwq under us, we 2346baf59022STejun Heo * are not going to wait. 2347baf59022STejun Heo */ 2348baf59022STejun Heo smp_rmb(); 2349baf59022STejun Heo cwq = get_work_cwq(work); 2350baf59022STejun Heo if (unlikely(!cwq || gcwq != cwq->gcwq)) 2351baf59022STejun Heo goto already_gone; 2352baf59022STejun Heo } else if (wait_executing) { 2353baf59022STejun Heo worker = find_worker_executing_work(gcwq, work); 2354baf59022STejun Heo if (!worker) 2355baf59022STejun Heo goto already_gone; 2356baf59022STejun Heo cwq = worker->current_cwq; 2357baf59022STejun Heo } else 2358baf59022STejun Heo goto already_gone; 2359baf59022STejun Heo 2360baf59022STejun Heo insert_wq_barrier(cwq, barr, work, worker); 2361baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2362baf59022STejun Heo 2363baf59022STejun Heo lock_map_acquire(&cwq->wq->lockdep_map); 2364baf59022STejun Heo lock_map_release(&cwq->wq->lockdep_map); 2365baf59022STejun Heo return true; 2366baf59022STejun Heo already_gone: 2367baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2368baf59022STejun Heo return false; 2369baf59022STejun Heo } 2370baf59022STejun Heo 2371db700897SOleg Nesterov /** 2372401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 2373401a8d04STejun Heo * @work: the work to flush 2374db700897SOleg Nesterov * 2375401a8d04STejun Heo * Wait until @work has finished execution. This function considers 2376401a8d04STejun Heo * only the last queueing instance of @work. If @work has been 2377401a8d04STejun Heo * enqueued across different CPUs on a non-reentrant workqueue or on 2378401a8d04STejun Heo * multiple workqueues, @work might still be executing on return on 2379401a8d04STejun Heo * some of the CPUs from earlier queueing. 2380a67da70dSOleg Nesterov * 2381401a8d04STejun Heo * If @work was queued only on a non-reentrant, ordered or unbound 2382401a8d04STejun Heo * workqueue, @work is guaranteed to be idle on return if it hasn't 2383401a8d04STejun Heo * been requeued since flush started. 2384401a8d04STejun Heo * 2385401a8d04STejun Heo * RETURNS: 2386401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2387401a8d04STejun Heo * %false if it was already idle. 2388db700897SOleg Nesterov */ 2389401a8d04STejun Heo bool flush_work(struct work_struct *work) 2390db700897SOleg Nesterov { 2391db700897SOleg Nesterov struct wq_barrier barr; 2392db700897SOleg Nesterov 2393baf59022STejun Heo if (start_flush_work(work, &barr, true)) { 2394db700897SOleg Nesterov wait_for_completion(&barr.done); 2395dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2396401a8d04STejun Heo return true; 2397baf59022STejun Heo } else 2398401a8d04STejun Heo return false; 2399db700897SOleg Nesterov } 2400db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2401db700897SOleg Nesterov 2402401a8d04STejun Heo static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) 2403401a8d04STejun Heo { 2404401a8d04STejun Heo struct wq_barrier barr; 2405401a8d04STejun Heo struct worker *worker; 2406401a8d04STejun Heo 2407401a8d04STejun Heo spin_lock_irq(&gcwq->lock); 2408401a8d04STejun Heo 2409401a8d04STejun Heo worker = find_worker_executing_work(gcwq, work); 2410401a8d04STejun Heo if (unlikely(worker)) 2411401a8d04STejun Heo insert_wq_barrier(worker->current_cwq, &barr, work, worker); 2412401a8d04STejun Heo 2413401a8d04STejun Heo spin_unlock_irq(&gcwq->lock); 2414401a8d04STejun Heo 2415401a8d04STejun Heo if (unlikely(worker)) { 2416401a8d04STejun Heo wait_for_completion(&barr.done); 2417401a8d04STejun Heo destroy_work_on_stack(&barr.work); 2418401a8d04STejun Heo return true; 2419401a8d04STejun Heo } else 2420401a8d04STejun Heo return false; 2421401a8d04STejun Heo } 2422401a8d04STejun Heo 2423401a8d04STejun Heo static bool wait_on_work(struct work_struct *work) 2424401a8d04STejun Heo { 2425401a8d04STejun Heo bool ret = false; 2426401a8d04STejun Heo int cpu; 2427401a8d04STejun Heo 2428401a8d04STejun Heo might_sleep(); 2429401a8d04STejun Heo 2430401a8d04STejun Heo lock_map_acquire(&work->lockdep_map); 2431401a8d04STejun Heo lock_map_release(&work->lockdep_map); 2432401a8d04STejun Heo 2433401a8d04STejun Heo for_each_gcwq_cpu(cpu) 2434401a8d04STejun Heo ret |= wait_on_cpu_work(get_gcwq(cpu), work); 2435401a8d04STejun Heo return ret; 2436401a8d04STejun Heo } 2437401a8d04STejun Heo 243809383498STejun Heo /** 243909383498STejun Heo * flush_work_sync - wait until a work has finished execution 244009383498STejun Heo * @work: the work to flush 244109383498STejun Heo * 244209383498STejun Heo * Wait until @work has finished execution. On return, it's 244309383498STejun Heo * guaranteed that all queueing instances of @work which happened 244409383498STejun Heo * before this function is called are finished. In other words, if 244509383498STejun Heo * @work hasn't been requeued since this function was called, @work is 244609383498STejun Heo * guaranteed to be idle on return. 244709383498STejun Heo * 244809383498STejun Heo * RETURNS: 244909383498STejun Heo * %true if flush_work_sync() waited for the work to finish execution, 245009383498STejun Heo * %false if it was already idle. 245109383498STejun Heo */ 245209383498STejun Heo bool flush_work_sync(struct work_struct *work) 245309383498STejun Heo { 245409383498STejun Heo struct wq_barrier barr; 245509383498STejun Heo bool pending, waited; 245609383498STejun Heo 245709383498STejun Heo /* we'll wait for executions separately, queue barr only if pending */ 245809383498STejun Heo pending = start_flush_work(work, &barr, false); 245909383498STejun Heo 246009383498STejun Heo /* wait for executions to finish */ 246109383498STejun Heo waited = wait_on_work(work); 246209383498STejun Heo 246309383498STejun Heo /* wait for the pending one */ 246409383498STejun Heo if (pending) { 246509383498STejun Heo wait_for_completion(&barr.done); 246609383498STejun Heo destroy_work_on_stack(&barr.work); 246709383498STejun Heo } 246809383498STejun Heo 246909383498STejun Heo return pending || waited; 247009383498STejun Heo } 247109383498STejun Heo EXPORT_SYMBOL_GPL(flush_work_sync); 247209383498STejun Heo 24736e84d644SOleg Nesterov /* 24741f1f642eSOleg Nesterov * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, 24756e84d644SOleg Nesterov * so this work can't be re-armed in any way. 24766e84d644SOleg Nesterov */ 24776e84d644SOleg Nesterov static int try_to_grab_pending(struct work_struct *work) 24786e84d644SOleg Nesterov { 24798b03ae3cSTejun Heo struct global_cwq *gcwq; 24801f1f642eSOleg Nesterov int ret = -1; 24816e84d644SOleg Nesterov 248222df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 24831f1f642eSOleg Nesterov return 0; 24846e84d644SOleg Nesterov 24856e84d644SOleg Nesterov /* 24866e84d644SOleg Nesterov * The queueing is in progress, or it is already queued. Try to 24876e84d644SOleg Nesterov * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 24886e84d644SOleg Nesterov */ 24897a22ad75STejun Heo gcwq = get_work_gcwq(work); 24907a22ad75STejun Heo if (!gcwq) 24916e84d644SOleg Nesterov return ret; 24926e84d644SOleg Nesterov 24938b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 24946e84d644SOleg Nesterov if (!list_empty(&work->entry)) { 24956e84d644SOleg Nesterov /* 24967a22ad75STejun Heo * This work is queued, but perhaps we locked the wrong gcwq. 24976e84d644SOleg Nesterov * In that case we must see the new value after rmb(), see 24986e84d644SOleg Nesterov * insert_work()->wmb(). 24996e84d644SOleg Nesterov */ 25006e84d644SOleg Nesterov smp_rmb(); 25017a22ad75STejun Heo if (gcwq == get_work_gcwq(work)) { 2502dc186ad7SThomas Gleixner debug_work_deactivate(work); 25036e84d644SOleg Nesterov list_del_init(&work->entry); 25047a22ad75STejun Heo cwq_dec_nr_in_flight(get_work_cwq(work), 25058a2e8e5dSTejun Heo get_work_color(work), 25068a2e8e5dSTejun Heo *work_data_bits(work) & WORK_STRUCT_DELAYED); 25076e84d644SOleg Nesterov ret = 1; 25086e84d644SOleg Nesterov } 25096e84d644SOleg Nesterov } 25108b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 25116e84d644SOleg Nesterov 25126e84d644SOleg Nesterov return ret; 25136e84d644SOleg Nesterov } 25146e84d644SOleg Nesterov 2515401a8d04STejun Heo static bool __cancel_work_timer(struct work_struct *work, 25161f1f642eSOleg Nesterov struct timer_list* timer) 25171f1f642eSOleg Nesterov { 25181f1f642eSOleg Nesterov int ret; 25191f1f642eSOleg Nesterov 25201f1f642eSOleg Nesterov do { 25211f1f642eSOleg Nesterov ret = (timer && likely(del_timer(timer))); 25221f1f642eSOleg Nesterov if (!ret) 25231f1f642eSOleg Nesterov ret = try_to_grab_pending(work); 25241f1f642eSOleg Nesterov wait_on_work(work); 25251f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 25261f1f642eSOleg Nesterov 25277a22ad75STejun Heo clear_work_data(work); 25281f1f642eSOleg Nesterov return ret; 25291f1f642eSOleg Nesterov } 25301f1f642eSOleg Nesterov 25316e84d644SOleg Nesterov /** 2532401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 2533401a8d04STejun Heo * @work: the work to cancel 25346e84d644SOleg Nesterov * 2535401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 2536401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 2537401a8d04STejun Heo * another workqueue. On return from this function, @work is 2538401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 25391f1f642eSOleg Nesterov * 2540401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 2541401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 25426e84d644SOleg Nesterov * 2543401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 25446e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 2545401a8d04STejun Heo * 2546401a8d04STejun Heo * RETURNS: 2547401a8d04STejun Heo * %true if @work was pending, %false otherwise. 25486e84d644SOleg Nesterov */ 2549401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 25506e84d644SOleg Nesterov { 25511f1f642eSOleg Nesterov return __cancel_work_timer(work, NULL); 2552b89deed3SOleg Nesterov } 255328e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2554b89deed3SOleg Nesterov 25556e84d644SOleg Nesterov /** 2556401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 2557401a8d04STejun Heo * @dwork: the delayed work to flush 25586e84d644SOleg Nesterov * 2559401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 2560401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 2561401a8d04STejun Heo * considers the last queueing instance of @dwork. 25621f1f642eSOleg Nesterov * 2563401a8d04STejun Heo * RETURNS: 2564401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2565401a8d04STejun Heo * %false if it was already idle. 25666e84d644SOleg Nesterov */ 2567401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 2568401a8d04STejun Heo { 2569401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 2570401a8d04STejun Heo __queue_work(raw_smp_processor_id(), 2571401a8d04STejun Heo get_work_cwq(&dwork->work)->wq, &dwork->work); 2572401a8d04STejun Heo return flush_work(&dwork->work); 2573401a8d04STejun Heo } 2574401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 2575401a8d04STejun Heo 2576401a8d04STejun Heo /** 257709383498STejun Heo * flush_delayed_work_sync - wait for a dwork to finish 257809383498STejun Heo * @dwork: the delayed work to flush 257909383498STejun Heo * 258009383498STejun Heo * Delayed timer is cancelled and the pending work is queued for 258109383498STejun Heo * execution immediately. Other than timer handling, its behavior 258209383498STejun Heo * is identical to flush_work_sync(). 258309383498STejun Heo * 258409383498STejun Heo * RETURNS: 258509383498STejun Heo * %true if flush_work_sync() waited for the work to finish execution, 258609383498STejun Heo * %false if it was already idle. 258709383498STejun Heo */ 258809383498STejun Heo bool flush_delayed_work_sync(struct delayed_work *dwork) 258909383498STejun Heo { 259009383498STejun Heo if (del_timer_sync(&dwork->timer)) 259109383498STejun Heo __queue_work(raw_smp_processor_id(), 259209383498STejun Heo get_work_cwq(&dwork->work)->wq, &dwork->work); 259309383498STejun Heo return flush_work_sync(&dwork->work); 259409383498STejun Heo } 259509383498STejun Heo EXPORT_SYMBOL(flush_delayed_work_sync); 259609383498STejun Heo 259709383498STejun Heo /** 2598401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 2599401a8d04STejun Heo * @dwork: the delayed work cancel 2600401a8d04STejun Heo * 2601401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 2602401a8d04STejun Heo * 2603401a8d04STejun Heo * RETURNS: 2604401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 2605401a8d04STejun Heo */ 2606401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 26076e84d644SOleg Nesterov { 26081f1f642eSOleg Nesterov return __cancel_work_timer(&dwork->work, &dwork->timer); 26096e84d644SOleg Nesterov } 2610f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 26111da177e4SLinus Torvalds 26120fcb78c2SRolf Eike Beer /** 26130fcb78c2SRolf Eike Beer * schedule_work - put work task in global workqueue 26140fcb78c2SRolf Eike Beer * @work: job to be done 26150fcb78c2SRolf Eike Beer * 26165b0f437dSBart Van Assche * Returns zero if @work was already on the kernel-global workqueue and 26175b0f437dSBart Van Assche * non-zero otherwise. 26185b0f437dSBart Van Assche * 26195b0f437dSBart Van Assche * This puts a job in the kernel-global workqueue if it was not already 26205b0f437dSBart Van Assche * queued and leaves it in the same position on the kernel-global 26215b0f437dSBart Van Assche * workqueue otherwise. 26220fcb78c2SRolf Eike Beer */ 26237ad5b3a5SHarvey Harrison int schedule_work(struct work_struct *work) 26241da177e4SLinus Torvalds { 2625d320c038STejun Heo return queue_work(system_wq, work); 26261da177e4SLinus Torvalds } 2627ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_work); 26281da177e4SLinus Torvalds 2629c1a220e7SZhang Rui /* 2630c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2631c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2632c1a220e7SZhang Rui * @work: job to be done 2633c1a220e7SZhang Rui * 2634c1a220e7SZhang Rui * This puts a job on a specific cpu 2635c1a220e7SZhang Rui */ 2636c1a220e7SZhang Rui int schedule_work_on(int cpu, struct work_struct *work) 2637c1a220e7SZhang Rui { 2638d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 2639c1a220e7SZhang Rui } 2640c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 2641c1a220e7SZhang Rui 26420fcb78c2SRolf Eike Beer /** 26430fcb78c2SRolf Eike Beer * schedule_delayed_work - put work task in global workqueue after delay 264452bad64dSDavid Howells * @dwork: job to be done 264552bad64dSDavid Howells * @delay: number of jiffies to wait or 0 for immediate execution 26460fcb78c2SRolf Eike Beer * 26470fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 26480fcb78c2SRolf Eike Beer * workqueue. 26490fcb78c2SRolf Eike Beer */ 26507ad5b3a5SHarvey Harrison int schedule_delayed_work(struct delayed_work *dwork, 265182f67cd9SIngo Molnar unsigned long delay) 26521da177e4SLinus Torvalds { 2653d320c038STejun Heo return queue_delayed_work(system_wq, dwork, delay); 26541da177e4SLinus Torvalds } 2655ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work); 26561da177e4SLinus Torvalds 26570fcb78c2SRolf Eike Beer /** 26580fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 26590fcb78c2SRolf Eike Beer * @cpu: cpu to use 266052bad64dSDavid Howells * @dwork: job to be done 26610fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 26620fcb78c2SRolf Eike Beer * 26630fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 26640fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 26650fcb78c2SRolf Eike Beer */ 26661da177e4SLinus Torvalds int schedule_delayed_work_on(int cpu, 266752bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 26681da177e4SLinus Torvalds { 2669d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 26701da177e4SLinus Torvalds } 2671ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 26721da177e4SLinus Torvalds 2673b6136773SAndrew Morton /** 2674b6136773SAndrew Morton * schedule_on_each_cpu - call a function on each online CPU from keventd 2675b6136773SAndrew Morton * @func: the function to call 2676b6136773SAndrew Morton * 2677b6136773SAndrew Morton * Returns zero on success. 2678b6136773SAndrew Morton * Returns -ve errno on failure. 2679b6136773SAndrew Morton * 2680b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 2681b6136773SAndrew Morton */ 268265f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 268315316ba8SChristoph Lameter { 268415316ba8SChristoph Lameter int cpu; 268538f51568SNamhyung Kim struct work_struct __percpu *works; 268615316ba8SChristoph Lameter 2687b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 2688b6136773SAndrew Morton if (!works) 268915316ba8SChristoph Lameter return -ENOMEM; 2690b6136773SAndrew Morton 269195402b38SGautham R Shenoy get_online_cpus(); 269293981800STejun Heo 269315316ba8SChristoph Lameter for_each_online_cpu(cpu) { 26949bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 26959bfb1839SIngo Molnar 26969bfb1839SIngo Molnar INIT_WORK(work, func); 26978de6d308SOleg Nesterov schedule_work_on(cpu, work); 269815316ba8SChristoph Lameter } 269993981800STejun Heo 270093981800STejun Heo for_each_online_cpu(cpu) 27018616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 270293981800STejun Heo 270395402b38SGautham R Shenoy put_online_cpus(); 2704b6136773SAndrew Morton free_percpu(works); 270515316ba8SChristoph Lameter return 0; 270615316ba8SChristoph Lameter } 270715316ba8SChristoph Lameter 2708eef6a7d5SAlan Stern /** 2709eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 2710eef6a7d5SAlan Stern * 2711eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 2712eef6a7d5SAlan Stern * completion. 2713eef6a7d5SAlan Stern * 2714eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 2715eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 2716eef6a7d5SAlan Stern * will lead to deadlock: 2717eef6a7d5SAlan Stern * 2718eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 2719eef6a7d5SAlan Stern * a lock held by your code or its caller. 2720eef6a7d5SAlan Stern * 2721eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 2722eef6a7d5SAlan Stern * 2723eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 2724eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 2725eef6a7d5SAlan Stern * what locks they need, which you have no control over. 2726eef6a7d5SAlan Stern * 2727eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 2728eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 2729eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 2730eef6a7d5SAlan Stern * cancel_work_sync() instead. 2731eef6a7d5SAlan Stern */ 27321da177e4SLinus Torvalds void flush_scheduled_work(void) 27331da177e4SLinus Torvalds { 2734d320c038STejun Heo flush_workqueue(system_wq); 27351da177e4SLinus Torvalds } 2736ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 27371da177e4SLinus Torvalds 27381da177e4SLinus Torvalds /** 27391fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 27401fa44ecaSJames Bottomley * @fn: the function to execute 27411fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 27421fa44ecaSJames Bottomley * be available when the work executes) 27431fa44ecaSJames Bottomley * 27441fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 27451fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 27461fa44ecaSJames Bottomley * 27471fa44ecaSJames Bottomley * Returns: 0 - function was executed 27481fa44ecaSJames Bottomley * 1 - function was scheduled for execution 27491fa44ecaSJames Bottomley */ 275065f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 27511fa44ecaSJames Bottomley { 27521fa44ecaSJames Bottomley if (!in_interrupt()) { 275365f27f38SDavid Howells fn(&ew->work); 27541fa44ecaSJames Bottomley return 0; 27551fa44ecaSJames Bottomley } 27561fa44ecaSJames Bottomley 275765f27f38SDavid Howells INIT_WORK(&ew->work, fn); 27581fa44ecaSJames Bottomley schedule_work(&ew->work); 27591fa44ecaSJames Bottomley 27601fa44ecaSJames Bottomley return 1; 27611fa44ecaSJames Bottomley } 27621fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 27631fa44ecaSJames Bottomley 27641da177e4SLinus Torvalds int keventd_up(void) 27651da177e4SLinus Torvalds { 2766d320c038STejun Heo return system_wq != NULL; 27671da177e4SLinus Torvalds } 27681da177e4SLinus Torvalds 2769bdbc5dd7STejun Heo static int alloc_cwqs(struct workqueue_struct *wq) 27701da177e4SLinus Torvalds { 27713af24433SOleg Nesterov /* 27720f900049STejun Heo * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. 27730f900049STejun Heo * Make sure that the alignment isn't lower than that of 27740f900049STejun Heo * unsigned long long. 27753af24433SOleg Nesterov */ 27760f900049STejun Heo const size_t size = sizeof(struct cpu_workqueue_struct); 27770f900049STejun Heo const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, 27780f900049STejun Heo __alignof__(unsigned long long)); 2779931ac77eSTejun Heo #ifdef CONFIG_SMP 2780931ac77eSTejun Heo bool percpu = !(wq->flags & WQ_UNBOUND); 2781931ac77eSTejun Heo #else 2782931ac77eSTejun Heo bool percpu = false; 2783931ac77eSTejun Heo #endif 27843af24433SOleg Nesterov 2785931ac77eSTejun Heo if (percpu) 2786f3421797STejun Heo wq->cpu_wq.pcpu = __alloc_percpu(size, align); 2787931ac77eSTejun Heo else { 27880f900049STejun Heo void *ptr; 2789e1d8aa9fSFrederic Weisbecker 27900f900049STejun Heo /* 2791f3421797STejun Heo * Allocate enough room to align cwq and put an extra 2792f3421797STejun Heo * pointer at the end pointing back to the originally 2793f3421797STejun Heo * allocated pointer which will be used for free. 27940f900049STejun Heo */ 2795bdbc5dd7STejun Heo ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); 2796bdbc5dd7STejun Heo if (ptr) { 2797bdbc5dd7STejun Heo wq->cpu_wq.single = PTR_ALIGN(ptr, align); 2798bdbc5dd7STejun Heo *(void **)(wq->cpu_wq.single + 1) = ptr; 2799bdbc5dd7STejun Heo } 28003af24433SOleg Nesterov } 28013af24433SOleg Nesterov 28020f900049STejun Heo /* just in case, make sure it's actually aligned */ 2803bdbc5dd7STejun Heo BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); 2804bdbc5dd7STejun Heo return wq->cpu_wq.v ? 0 : -ENOMEM; 28050f900049STejun Heo } 28060f900049STejun Heo 2807bdbc5dd7STejun Heo static void free_cwqs(struct workqueue_struct *wq) 280806ba38a9SOleg Nesterov { 2809931ac77eSTejun Heo #ifdef CONFIG_SMP 2810931ac77eSTejun Heo bool percpu = !(wq->flags & WQ_UNBOUND); 2811931ac77eSTejun Heo #else 2812931ac77eSTejun Heo bool percpu = false; 2813931ac77eSTejun Heo #endif 281406ba38a9SOleg Nesterov 2815931ac77eSTejun Heo if (percpu) 2816bdbc5dd7STejun Heo free_percpu(wq->cpu_wq.pcpu); 2817f3421797STejun Heo else if (wq->cpu_wq.single) { 2818f3421797STejun Heo /* the pointer to free is stored right after the cwq */ 2819f3421797STejun Heo kfree(*(void **)(wq->cpu_wq.single + 1)); 282006ba38a9SOleg Nesterov } 282106ba38a9SOleg Nesterov } 282206ba38a9SOleg Nesterov 2823f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 2824f3421797STejun Heo const char *name) 2825b71ab8c2STejun Heo { 2826f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 2827f3421797STejun Heo 2828f3421797STejun Heo if (max_active < 1 || max_active > lim) 2829b71ab8c2STejun Heo printk(KERN_WARNING "workqueue: max_active %d requested for %s " 2830b71ab8c2STejun Heo "is out of range, clamping between %d and %d\n", 2831f3421797STejun Heo max_active, name, 1, lim); 2832b71ab8c2STejun Heo 2833f3421797STejun Heo return clamp_val(max_active, 1, lim); 2834b71ab8c2STejun Heo } 2835b71ab8c2STejun Heo 2836d320c038STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *name, 283797e37d7bSTejun Heo unsigned int flags, 28381e19ffc6STejun Heo int max_active, 2839eb13ba87SJohannes Berg struct lock_class_key *key, 2840eb13ba87SJohannes Berg const char *lock_name) 28413af24433SOleg Nesterov { 28423af24433SOleg Nesterov struct workqueue_struct *wq; 2843c34056a3STejun Heo unsigned int cpu; 28443af24433SOleg Nesterov 2845f3421797STejun Heo /* 2846f3421797STejun Heo * Unbound workqueues aren't concurrency managed and should be 2847f3421797STejun Heo * dispatched to workers immediately. 2848f3421797STejun Heo */ 2849f3421797STejun Heo if (flags & WQ_UNBOUND) 2850f3421797STejun Heo flags |= WQ_HIGHPRI; 2851f3421797STejun Heo 2852d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 2853f3421797STejun Heo max_active = wq_clamp_max_active(max_active, flags, name); 28543af24433SOleg Nesterov 28553af24433SOleg Nesterov wq = kzalloc(sizeof(*wq), GFP_KERNEL); 28563af24433SOleg Nesterov if (!wq) 28574690c4abSTejun Heo goto err; 28583af24433SOleg Nesterov 285997e37d7bSTejun Heo wq->flags = flags; 2860a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 286173f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 286273f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 0); 286373f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 286473f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 28653af24433SOleg Nesterov 28663af24433SOleg Nesterov wq->name = name; 2867eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 2868cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 28693af24433SOleg Nesterov 2870bdbc5dd7STejun Heo if (alloc_cwqs(wq) < 0) 2871bdbc5dd7STejun Heo goto err; 2872bdbc5dd7STejun Heo 2873f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 28741537663fSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 28758b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 28761537663fSTejun Heo 28770f900049STejun Heo BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 28788b03ae3cSTejun Heo cwq->gcwq = gcwq; 2879c34056a3STejun Heo cwq->wq = wq; 288073f53c4aSTejun Heo cwq->flush_color = -1; 28811e19ffc6STejun Heo cwq->max_active = max_active; 28821e19ffc6STejun Heo INIT_LIST_HEAD(&cwq->delayed_works); 2883e22bee78STejun Heo } 28841537663fSTejun Heo 2885e22bee78STejun Heo if (flags & WQ_RESCUER) { 2886e22bee78STejun Heo struct worker *rescuer; 2887e22bee78STejun Heo 2888f2e005aaSTejun Heo if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) 2889e22bee78STejun Heo goto err; 2890e22bee78STejun Heo 2891e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 2892e22bee78STejun Heo if (!rescuer) 2893e22bee78STejun Heo goto err; 2894e22bee78STejun Heo 2895e22bee78STejun Heo rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); 2896e22bee78STejun Heo if (IS_ERR(rescuer->task)) 2897e22bee78STejun Heo goto err; 2898e22bee78STejun Heo 2899e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 2900e22bee78STejun Heo wake_up_process(rescuer->task); 29013af24433SOleg Nesterov } 29021537663fSTejun Heo 29033af24433SOleg Nesterov /* 2904a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 2905a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 2906a0a1a5fdSTejun Heo * workqueue to workqueues list. 29073af24433SOleg Nesterov */ 29083af24433SOleg Nesterov spin_lock(&workqueue_lock); 2909a0a1a5fdSTejun Heo 2910a0a1a5fdSTejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) 2911f3421797STejun Heo for_each_cwq_cpu(cpu, wq) 2912a0a1a5fdSTejun Heo get_cwq(cpu, wq)->max_active = 0; 2913a0a1a5fdSTejun Heo 29143af24433SOleg Nesterov list_add(&wq->list, &workqueues); 2915a0a1a5fdSTejun Heo 29163af24433SOleg Nesterov spin_unlock(&workqueue_lock); 29173af24433SOleg Nesterov 29183af24433SOleg Nesterov return wq; 29194690c4abSTejun Heo err: 29204690c4abSTejun Heo if (wq) { 2921bdbc5dd7STejun Heo free_cwqs(wq); 2922f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 2923e22bee78STejun Heo kfree(wq->rescuer); 29244690c4abSTejun Heo kfree(wq); 29253af24433SOleg Nesterov } 29264690c4abSTejun Heo return NULL; 29271da177e4SLinus Torvalds } 2928d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 29291da177e4SLinus Torvalds 29303af24433SOleg Nesterov /** 29313af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 29323af24433SOleg Nesterov * @wq: target workqueue 29333af24433SOleg Nesterov * 29343af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 29353af24433SOleg Nesterov */ 29363af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 29373af24433SOleg Nesterov { 2938c8e55f36STejun Heo unsigned int cpu; 29393af24433SOleg Nesterov 2940e41e704bSTejun Heo wq->flags |= WQ_DYING; 2941a0a1a5fdSTejun Heo flush_workqueue(wq); 2942a0a1a5fdSTejun Heo 2943a0a1a5fdSTejun Heo /* 2944a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 2945a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 2946a0a1a5fdSTejun Heo */ 294795402b38SGautham R Shenoy spin_lock(&workqueue_lock); 29483af24433SOleg Nesterov list_del(&wq->list); 294995402b38SGautham R Shenoy spin_unlock(&workqueue_lock); 29503af24433SOleg Nesterov 2951e22bee78STejun Heo /* sanity check */ 2952f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 295373f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 295473f53c4aSTejun Heo int i; 29553af24433SOleg Nesterov 295673f53c4aSTejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 295773f53c4aSTejun Heo BUG_ON(cwq->nr_in_flight[i]); 29581e19ffc6STejun Heo BUG_ON(cwq->nr_active); 29591e19ffc6STejun Heo BUG_ON(!list_empty(&cwq->delayed_works)); 296073f53c4aSTejun Heo } 29611537663fSTejun Heo 2962e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 2963e22bee78STejun Heo kthread_stop(wq->rescuer->task); 2964f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 29658d9df9f0SXiaotian Feng kfree(wq->rescuer); 2966e22bee78STejun Heo } 2967e22bee78STejun Heo 2968bdbc5dd7STejun Heo free_cwqs(wq); 29693af24433SOleg Nesterov kfree(wq); 29703af24433SOleg Nesterov } 29713af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 29723af24433SOleg Nesterov 2973dcd989cbSTejun Heo /** 2974dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 2975dcd989cbSTejun Heo * @wq: target workqueue 2976dcd989cbSTejun Heo * @max_active: new max_active value. 2977dcd989cbSTejun Heo * 2978dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 2979dcd989cbSTejun Heo * 2980dcd989cbSTejun Heo * CONTEXT: 2981dcd989cbSTejun Heo * Don't call from IRQ context. 2982dcd989cbSTejun Heo */ 2983dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 2984dcd989cbSTejun Heo { 2985dcd989cbSTejun Heo unsigned int cpu; 2986dcd989cbSTejun Heo 2987f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 2988dcd989cbSTejun Heo 2989dcd989cbSTejun Heo spin_lock(&workqueue_lock); 2990dcd989cbSTejun Heo 2991dcd989cbSTejun Heo wq->saved_max_active = max_active; 2992dcd989cbSTejun Heo 2993f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 2994dcd989cbSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 2995dcd989cbSTejun Heo 2996dcd989cbSTejun Heo spin_lock_irq(&gcwq->lock); 2997dcd989cbSTejun Heo 2998dcd989cbSTejun Heo if (!(wq->flags & WQ_FREEZEABLE) || 2999dcd989cbSTejun Heo !(gcwq->flags & GCWQ_FREEZING)) 3000dcd989cbSTejun Heo get_cwq(gcwq->cpu, wq)->max_active = max_active; 3001dcd989cbSTejun Heo 3002dcd989cbSTejun Heo spin_unlock_irq(&gcwq->lock); 3003dcd989cbSTejun Heo } 3004dcd989cbSTejun Heo 3005dcd989cbSTejun Heo spin_unlock(&workqueue_lock); 3006dcd989cbSTejun Heo } 3007dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 3008dcd989cbSTejun Heo 3009dcd989cbSTejun Heo /** 3010dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 3011dcd989cbSTejun Heo * @cpu: CPU in question 3012dcd989cbSTejun Heo * @wq: target workqueue 3013dcd989cbSTejun Heo * 3014dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 3015dcd989cbSTejun Heo * no synchronization around this function and the test result is 3016dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3017dcd989cbSTejun Heo * 3018dcd989cbSTejun Heo * RETURNS: 3019dcd989cbSTejun Heo * %true if congested, %false otherwise. 3020dcd989cbSTejun Heo */ 3021dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 3022dcd989cbSTejun Heo { 3023dcd989cbSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3024dcd989cbSTejun Heo 3025dcd989cbSTejun Heo return !list_empty(&cwq->delayed_works); 3026dcd989cbSTejun Heo } 3027dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 3028dcd989cbSTejun Heo 3029dcd989cbSTejun Heo /** 3030dcd989cbSTejun Heo * work_cpu - return the last known associated cpu for @work 3031dcd989cbSTejun Heo * @work: the work of interest 3032dcd989cbSTejun Heo * 3033dcd989cbSTejun Heo * RETURNS: 3034bdbc5dd7STejun Heo * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. 3035dcd989cbSTejun Heo */ 3036dcd989cbSTejun Heo unsigned int work_cpu(struct work_struct *work) 3037dcd989cbSTejun Heo { 3038dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3039dcd989cbSTejun Heo 3040bdbc5dd7STejun Heo return gcwq ? gcwq->cpu : WORK_CPU_NONE; 3041dcd989cbSTejun Heo } 3042dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_cpu); 3043dcd989cbSTejun Heo 3044dcd989cbSTejun Heo /** 3045dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 3046dcd989cbSTejun Heo * @work: the work to be tested 3047dcd989cbSTejun Heo * 3048dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 3049dcd989cbSTejun Heo * synchronization around this function and the test result is 3050dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3051dcd989cbSTejun Heo * Especially for reentrant wqs, the pending state might hide the 3052dcd989cbSTejun Heo * running state. 3053dcd989cbSTejun Heo * 3054dcd989cbSTejun Heo * RETURNS: 3055dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 3056dcd989cbSTejun Heo */ 3057dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 3058dcd989cbSTejun Heo { 3059dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3060dcd989cbSTejun Heo unsigned long flags; 3061dcd989cbSTejun Heo unsigned int ret = 0; 3062dcd989cbSTejun Heo 3063dcd989cbSTejun Heo if (!gcwq) 3064dcd989cbSTejun Heo return false; 3065dcd989cbSTejun Heo 3066dcd989cbSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 3067dcd989cbSTejun Heo 3068dcd989cbSTejun Heo if (work_pending(work)) 3069dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 3070dcd989cbSTejun Heo if (find_worker_executing_work(gcwq, work)) 3071dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 3072dcd989cbSTejun Heo 3073dcd989cbSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 3074dcd989cbSTejun Heo 3075dcd989cbSTejun Heo return ret; 3076dcd989cbSTejun Heo } 3077dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 3078dcd989cbSTejun Heo 3079db7bccf4STejun Heo /* 3080db7bccf4STejun Heo * CPU hotplug. 3081db7bccf4STejun Heo * 3082e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 3083e22bee78STejun Heo * are a lot of assumptions on strong associations among work, cwq and 3084e22bee78STejun Heo * gcwq which make migrating pending and scheduled works very 3085e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 3086e22bee78STejun Heo * gcwqs serve mix of short, long and very long running works making 3087e22bee78STejun Heo * blocked draining impractical. 3088e22bee78STejun Heo * 3089e22bee78STejun Heo * This is solved by allowing a gcwq to be detached from CPU, running 3090e22bee78STejun Heo * it with unbound (rogue) workers and allowing it to be reattached 3091e22bee78STejun Heo * later if the cpu comes back online. A separate thread is created 3092e22bee78STejun Heo * to govern a gcwq in such state and is called the trustee of the 3093e22bee78STejun Heo * gcwq. 3094db7bccf4STejun Heo * 3095db7bccf4STejun Heo * Trustee states and their descriptions. 3096db7bccf4STejun Heo * 3097db7bccf4STejun Heo * START Command state used on startup. On CPU_DOWN_PREPARE, a 3098db7bccf4STejun Heo * new trustee is started with this state. 3099db7bccf4STejun Heo * 3100db7bccf4STejun Heo * IN_CHARGE Once started, trustee will enter this state after 3101e22bee78STejun Heo * assuming the manager role and making all existing 3102e22bee78STejun Heo * workers rogue. DOWN_PREPARE waits for trustee to 3103e22bee78STejun Heo * enter this state. After reaching IN_CHARGE, trustee 3104e22bee78STejun Heo * tries to execute the pending worklist until it's empty 3105e22bee78STejun Heo * and the state is set to BUTCHER, or the state is set 3106e22bee78STejun Heo * to RELEASE. 3107db7bccf4STejun Heo * 3108db7bccf4STejun Heo * BUTCHER Command state which is set by the cpu callback after 3109db7bccf4STejun Heo * the cpu has went down. Once this state is set trustee 3110db7bccf4STejun Heo * knows that there will be no new works on the worklist 3111db7bccf4STejun Heo * and once the worklist is empty it can proceed to 3112db7bccf4STejun Heo * killing idle workers. 3113db7bccf4STejun Heo * 3114db7bccf4STejun Heo * RELEASE Command state which is set by the cpu callback if the 3115db7bccf4STejun Heo * cpu down has been canceled or it has come online 3116db7bccf4STejun Heo * again. After recognizing this state, trustee stops 3117e22bee78STejun Heo * trying to drain or butcher and clears ROGUE, rebinds 3118e22bee78STejun Heo * all remaining workers back to the cpu and releases 3119e22bee78STejun Heo * manager role. 3120db7bccf4STejun Heo * 3121db7bccf4STejun Heo * DONE Trustee will enter this state after BUTCHER or RELEASE 3122db7bccf4STejun Heo * is complete. 3123db7bccf4STejun Heo * 3124db7bccf4STejun Heo * trustee CPU draining 3125db7bccf4STejun Heo * took over down complete 3126db7bccf4STejun Heo * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE 3127db7bccf4STejun Heo * | | ^ 3128db7bccf4STejun Heo * | CPU is back online v return workers | 3129db7bccf4STejun Heo * ----------------> RELEASE -------------- 3130db7bccf4STejun Heo */ 3131db7bccf4STejun Heo 3132db7bccf4STejun Heo /** 3133db7bccf4STejun Heo * trustee_wait_event_timeout - timed event wait for trustee 3134db7bccf4STejun Heo * @cond: condition to wait for 3135db7bccf4STejun Heo * @timeout: timeout in jiffies 3136db7bccf4STejun Heo * 3137db7bccf4STejun Heo * wait_event_timeout() for trustee to use. Handles locking and 3138db7bccf4STejun Heo * checks for RELEASE request. 3139db7bccf4STejun Heo * 3140db7bccf4STejun Heo * CONTEXT: 3141db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3142db7bccf4STejun Heo * multiple times. To be used by trustee. 3143db7bccf4STejun Heo * 3144db7bccf4STejun Heo * RETURNS: 3145db7bccf4STejun Heo * Positive indicating left time if @cond is satisfied, 0 if timed 3146db7bccf4STejun Heo * out, -1 if canceled. 3147db7bccf4STejun Heo */ 3148db7bccf4STejun Heo #define trustee_wait_event_timeout(cond, timeout) ({ \ 3149db7bccf4STejun Heo long __ret = (timeout); \ 3150db7bccf4STejun Heo while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ 3151db7bccf4STejun Heo __ret) { \ 3152db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); \ 3153db7bccf4STejun Heo __wait_event_timeout(gcwq->trustee_wait, (cond) || \ 3154db7bccf4STejun Heo (gcwq->trustee_state == TRUSTEE_RELEASE), \ 3155db7bccf4STejun Heo __ret); \ 3156db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); \ 3157db7bccf4STejun Heo } \ 3158db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ 3159db7bccf4STejun Heo }) 3160db7bccf4STejun Heo 3161db7bccf4STejun Heo /** 3162db7bccf4STejun Heo * trustee_wait_event - event wait for trustee 3163db7bccf4STejun Heo * @cond: condition to wait for 3164db7bccf4STejun Heo * 3165db7bccf4STejun Heo * wait_event() for trustee to use. Automatically handles locking and 3166db7bccf4STejun Heo * checks for CANCEL request. 3167db7bccf4STejun Heo * 3168db7bccf4STejun Heo * CONTEXT: 3169db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3170db7bccf4STejun Heo * multiple times. To be used by trustee. 3171db7bccf4STejun Heo * 3172db7bccf4STejun Heo * RETURNS: 3173db7bccf4STejun Heo * 0 if @cond is satisfied, -1 if canceled. 3174db7bccf4STejun Heo */ 3175db7bccf4STejun Heo #define trustee_wait_event(cond) ({ \ 3176db7bccf4STejun Heo long __ret1; \ 3177db7bccf4STejun Heo __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ 3178db7bccf4STejun Heo __ret1 < 0 ? -1 : 0; \ 3179db7bccf4STejun Heo }) 3180db7bccf4STejun Heo 3181db7bccf4STejun Heo static int __cpuinit trustee_thread(void *__gcwq) 3182db7bccf4STejun Heo { 3183db7bccf4STejun Heo struct global_cwq *gcwq = __gcwq; 3184db7bccf4STejun Heo struct worker *worker; 3185e22bee78STejun Heo struct work_struct *work; 3186db7bccf4STejun Heo struct hlist_node *pos; 3187e22bee78STejun Heo long rc; 3188db7bccf4STejun Heo int i; 3189db7bccf4STejun Heo 3190db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3191db7bccf4STejun Heo 3192db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3193db7bccf4STejun Heo /* 3194e22bee78STejun Heo * Claim the manager position and make all workers rogue. 3195e22bee78STejun Heo * Trustee must be bound to the target cpu and can't be 3196e22bee78STejun Heo * cancelled. 3197db7bccf4STejun Heo */ 3198db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3199e22bee78STejun Heo rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); 3200e22bee78STejun Heo BUG_ON(rc < 0); 3201e22bee78STejun Heo 3202e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 3203db7bccf4STejun Heo 3204db7bccf4STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) 3205cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3206db7bccf4STejun Heo 3207db7bccf4STejun Heo for_each_busy_worker(worker, i, pos, gcwq) 3208cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3209db7bccf4STejun Heo 3210db7bccf4STejun Heo /* 3211e22bee78STejun Heo * Call schedule() so that we cross rq->lock and thus can 3212e22bee78STejun Heo * guarantee sched callbacks see the rogue flag. This is 3213e22bee78STejun Heo * necessary as scheduler callbacks may be invoked from other 3214e22bee78STejun Heo * cpus. 3215e22bee78STejun Heo */ 3216e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3217e22bee78STejun Heo schedule(); 3218e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3219e22bee78STejun Heo 3220e22bee78STejun Heo /* 3221cb444766STejun Heo * Sched callbacks are disabled now. Zap nr_running. After 3222cb444766STejun Heo * this, nr_running stays zero and need_more_worker() and 3223cb444766STejun Heo * keep_working() are always true as long as the worklist is 3224cb444766STejun Heo * not empty. 3225e22bee78STejun Heo */ 3226cb444766STejun Heo atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); 3227e22bee78STejun Heo 3228e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3229e22bee78STejun Heo del_timer_sync(&gcwq->idle_timer); 3230e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3231e22bee78STejun Heo 3232e22bee78STejun Heo /* 3233db7bccf4STejun Heo * We're now in charge. Notify and proceed to drain. We need 3234db7bccf4STejun Heo * to keep the gcwq running during the whole CPU down 3235db7bccf4STejun Heo * procedure as other cpu hotunplug callbacks may need to 3236db7bccf4STejun Heo * flush currently running tasks. 3237db7bccf4STejun Heo */ 3238db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_IN_CHARGE; 3239db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3240db7bccf4STejun Heo 3241db7bccf4STejun Heo /* 3242db7bccf4STejun Heo * The original cpu is in the process of dying and may go away 3243db7bccf4STejun Heo * anytime now. When that happens, we and all workers would 3244e22bee78STejun Heo * be migrated to other cpus. Try draining any left work. We 3245e22bee78STejun Heo * want to get it over with ASAP - spam rescuers, wake up as 3246e22bee78STejun Heo * many idlers as necessary and create new ones till the 3247e22bee78STejun Heo * worklist is empty. Note that if the gcwq is frozen, there 3248e22bee78STejun Heo * may be frozen works in freezeable cwqs. Don't declare 3249e22bee78STejun Heo * completion while frozen. 3250db7bccf4STejun Heo */ 3251db7bccf4STejun Heo while (gcwq->nr_workers != gcwq->nr_idle || 3252db7bccf4STejun Heo gcwq->flags & GCWQ_FREEZING || 3253db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_IN_CHARGE) { 3254e22bee78STejun Heo int nr_works = 0; 3255e22bee78STejun Heo 3256e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) { 3257e22bee78STejun Heo send_mayday(work); 3258e22bee78STejun Heo nr_works++; 3259e22bee78STejun Heo } 3260e22bee78STejun Heo 3261e22bee78STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) { 3262e22bee78STejun Heo if (!nr_works--) 3263e22bee78STejun Heo break; 3264e22bee78STejun Heo wake_up_process(worker->task); 3265e22bee78STejun Heo } 3266e22bee78STejun Heo 3267e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 3268e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3269e22bee78STejun Heo worker = create_worker(gcwq, false); 3270e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3271e22bee78STejun Heo if (worker) { 3272cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3273e22bee78STejun Heo start_worker(worker); 3274e22bee78STejun Heo } 3275e22bee78STejun Heo } 3276e22bee78STejun Heo 3277db7bccf4STejun Heo /* give a breather */ 3278db7bccf4STejun Heo if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) 3279db7bccf4STejun Heo break; 3280db7bccf4STejun Heo } 3281db7bccf4STejun Heo 3282e22bee78STejun Heo /* 3283e22bee78STejun Heo * Either all works have been scheduled and cpu is down, or 3284e22bee78STejun Heo * cpu down has already been canceled. Wait for and butcher 3285e22bee78STejun Heo * all workers till we're canceled. 3286e22bee78STejun Heo */ 3287e22bee78STejun Heo do { 3288e22bee78STejun Heo rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); 3289e22bee78STejun Heo while (!list_empty(&gcwq->idle_list)) 3290e22bee78STejun Heo destroy_worker(list_first_entry(&gcwq->idle_list, 3291e22bee78STejun Heo struct worker, entry)); 3292e22bee78STejun Heo } while (gcwq->nr_workers && rc >= 0); 3293e22bee78STejun Heo 3294e22bee78STejun Heo /* 3295e22bee78STejun Heo * At this point, either draining has completed and no worker 3296e22bee78STejun Heo * is left, or cpu down has been canceled or the cpu is being 3297e22bee78STejun Heo * brought back up. There shouldn't be any idle one left. 3298e22bee78STejun Heo * Tell the remaining busy ones to rebind once it finishes the 3299e22bee78STejun Heo * currently scheduled works by scheduling the rebind_work. 3300e22bee78STejun Heo */ 3301e22bee78STejun Heo WARN_ON(!list_empty(&gcwq->idle_list)); 3302e22bee78STejun Heo 3303e22bee78STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 3304e22bee78STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 3305e22bee78STejun Heo 3306e22bee78STejun Heo /* 3307e22bee78STejun Heo * Rebind_work may race with future cpu hotplug 3308e22bee78STejun Heo * operations. Use a separate flag to mark that 3309e22bee78STejun Heo * rebinding is scheduled. 3310e22bee78STejun Heo */ 3311cb444766STejun Heo worker->flags |= WORKER_REBIND; 3312cb444766STejun Heo worker->flags &= ~WORKER_ROGUE; 3313e22bee78STejun Heo 3314e22bee78STejun Heo /* queue rebind_work, wq doesn't matter, use the default one */ 3315e22bee78STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 3316e22bee78STejun Heo work_data_bits(rebind_work))) 3317e22bee78STejun Heo continue; 3318e22bee78STejun Heo 3319e22bee78STejun Heo debug_work_activate(rebind_work); 3320d320c038STejun Heo insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, 3321e22bee78STejun Heo worker->scheduled.next, 3322e22bee78STejun Heo work_color_to_flags(WORK_NO_COLOR)); 3323e22bee78STejun Heo } 3324e22bee78STejun Heo 3325e22bee78STejun Heo /* relinquish manager role */ 3326e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 3327e22bee78STejun Heo 3328db7bccf4STejun Heo /* notify completion */ 3329db7bccf4STejun Heo gcwq->trustee = NULL; 3330db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3331db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3332db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3333db7bccf4STejun Heo return 0; 3334db7bccf4STejun Heo } 3335db7bccf4STejun Heo 3336db7bccf4STejun Heo /** 3337db7bccf4STejun Heo * wait_trustee_state - wait for trustee to enter the specified state 3338db7bccf4STejun Heo * @gcwq: gcwq the trustee of interest belongs to 3339db7bccf4STejun Heo * @state: target state to wait for 3340db7bccf4STejun Heo * 3341db7bccf4STejun Heo * Wait for the trustee to reach @state. DONE is already matched. 3342db7bccf4STejun Heo * 3343db7bccf4STejun Heo * CONTEXT: 3344db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3345db7bccf4STejun Heo * multiple times. To be used by cpu_callback. 3346db7bccf4STejun Heo */ 3347db7bccf4STejun Heo static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) 334806bd6ebfSNamhyung Kim __releases(&gcwq->lock) 334906bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 3350db7bccf4STejun Heo { 3351db7bccf4STejun Heo if (!(gcwq->trustee_state == state || 3352db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE)) { 3353db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3354db7bccf4STejun Heo __wait_event(gcwq->trustee_wait, 3355db7bccf4STejun Heo gcwq->trustee_state == state || 3356db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE); 3357db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3358db7bccf4STejun Heo } 3359db7bccf4STejun Heo } 3360db7bccf4STejun Heo 33619c7b216dSChandra Seetharaman static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 33621da177e4SLinus Torvalds unsigned long action, 33631da177e4SLinus Torvalds void *hcpu) 33641da177e4SLinus Torvalds { 33653af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 3366db7bccf4STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3367db7bccf4STejun Heo struct task_struct *new_trustee = NULL; 3368e22bee78STejun Heo struct worker *uninitialized_var(new_worker); 3369db7bccf4STejun Heo unsigned long flags; 33701da177e4SLinus Torvalds 33718bb78442SRafael J. Wysocki action &= ~CPU_TASKS_FROZEN; 33728bb78442SRafael J. Wysocki 33731da177e4SLinus Torvalds switch (action) { 3374db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3375db7bccf4STejun Heo new_trustee = kthread_create(trustee_thread, gcwq, 3376db7bccf4STejun Heo "workqueue_trustee/%d\n", cpu); 3377db7bccf4STejun Heo if (IS_ERR(new_trustee)) 3378db7bccf4STejun Heo return notifier_from_errno(PTR_ERR(new_trustee)); 3379db7bccf4STejun Heo kthread_bind(new_trustee, cpu); 3380e22bee78STejun Heo /* fall through */ 33813af24433SOleg Nesterov case CPU_UP_PREPARE: 3382e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3383e22bee78STejun Heo new_worker = create_worker(gcwq, false); 3384e22bee78STejun Heo if (!new_worker) { 3385e22bee78STejun Heo if (new_trustee) 3386e22bee78STejun Heo kthread_stop(new_trustee); 3387e22bee78STejun Heo return NOTIFY_BAD; 33883af24433SOleg Nesterov } 3389db7bccf4STejun Heo } 33901537663fSTejun Heo 3391db7bccf4STejun Heo /* some are called w/ irq disabled, don't disturb irq status */ 3392db7bccf4STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 33933af24433SOleg Nesterov 33943af24433SOleg Nesterov switch (action) { 3395db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3396db7bccf4STejun Heo /* initialize trustee and tell it to acquire the gcwq */ 3397db7bccf4STejun Heo BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); 3398db7bccf4STejun Heo gcwq->trustee = new_trustee; 3399db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_START; 3400db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3401db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); 3402e22bee78STejun Heo /* fall through */ 34033af24433SOleg Nesterov case CPU_UP_PREPARE: 3404e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3405e22bee78STejun Heo gcwq->first_idle = new_worker; 34061da177e4SLinus Torvalds break; 34071da177e4SLinus Torvalds 3408e22bee78STejun Heo case CPU_DYING: 3409e22bee78STejun Heo /* 3410e22bee78STejun Heo * Before this, the trustee and all workers except for 3411e22bee78STejun Heo * the ones which are still executing works from 3412e22bee78STejun Heo * before the last CPU down must be on the cpu. After 3413e22bee78STejun Heo * this, they'll all be diasporas. 3414e22bee78STejun Heo */ 3415e22bee78STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 3416db7bccf4STejun Heo break; 3417db7bccf4STejun Heo 34183da1c84cSOleg Nesterov case CPU_POST_DEAD: 3419db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_BUTCHER; 3420e22bee78STejun Heo /* fall through */ 3421e22bee78STejun Heo case CPU_UP_CANCELED: 3422e22bee78STejun Heo destroy_worker(gcwq->first_idle); 3423e22bee78STejun Heo gcwq->first_idle = NULL; 3424db7bccf4STejun Heo break; 3425db7bccf4STejun Heo 3426db7bccf4STejun Heo case CPU_DOWN_FAILED: 34271da177e4SLinus Torvalds case CPU_ONLINE: 3428e22bee78STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3429db7bccf4STejun Heo if (gcwq->trustee_state != TRUSTEE_DONE) { 3430db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_RELEASE; 3431db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3432db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_DONE); 3433db7bccf4STejun Heo } 34341da177e4SLinus Torvalds 3435e22bee78STejun Heo /* 3436e22bee78STejun Heo * Trustee is done and there might be no worker left. 3437e22bee78STejun Heo * Put the first_idle in and request a real manager to 3438e22bee78STejun Heo * take a look. 3439e22bee78STejun Heo */ 3440e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3441e22bee78STejun Heo kthread_bind(gcwq->first_idle->task, cpu); 3442e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3443e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 3444e22bee78STejun Heo start_worker(gcwq->first_idle); 3445e22bee78STejun Heo gcwq->first_idle = NULL; 34461da177e4SLinus Torvalds break; 34471da177e4SLinus Torvalds } 34481da177e4SLinus Torvalds 3449db7bccf4STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 345000dfcaf7SOleg Nesterov 34511537663fSTejun Heo return notifier_from_errno(0); 34521da177e4SLinus Torvalds } 34531da177e4SLinus Torvalds 34542d3854a3SRusty Russell #ifdef CONFIG_SMP 34558ccad40dSRusty Russell 34562d3854a3SRusty Russell struct work_for_cpu { 34576b44003eSAndrew Morton struct completion completion; 34582d3854a3SRusty Russell long (*fn)(void *); 34592d3854a3SRusty Russell void *arg; 34602d3854a3SRusty Russell long ret; 34612d3854a3SRusty Russell }; 34622d3854a3SRusty Russell 34636b44003eSAndrew Morton static int do_work_for_cpu(void *_wfc) 34642d3854a3SRusty Russell { 34656b44003eSAndrew Morton struct work_for_cpu *wfc = _wfc; 34662d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 34676b44003eSAndrew Morton complete(&wfc->completion); 34686b44003eSAndrew Morton return 0; 34692d3854a3SRusty Russell } 34702d3854a3SRusty Russell 34712d3854a3SRusty Russell /** 34722d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 34732d3854a3SRusty Russell * @cpu: the cpu to run on 34742d3854a3SRusty Russell * @fn: the function to run 34752d3854a3SRusty Russell * @arg: the function arg 34762d3854a3SRusty Russell * 347731ad9081SRusty Russell * This will return the value @fn returns. 347831ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 34796b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 34802d3854a3SRusty Russell */ 34812d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 34822d3854a3SRusty Russell { 34836b44003eSAndrew Morton struct task_struct *sub_thread; 34846b44003eSAndrew Morton struct work_for_cpu wfc = { 34856b44003eSAndrew Morton .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), 34866b44003eSAndrew Morton .fn = fn, 34876b44003eSAndrew Morton .arg = arg, 34886b44003eSAndrew Morton }; 34892d3854a3SRusty Russell 34906b44003eSAndrew Morton sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); 34916b44003eSAndrew Morton if (IS_ERR(sub_thread)) 34926b44003eSAndrew Morton return PTR_ERR(sub_thread); 34936b44003eSAndrew Morton kthread_bind(sub_thread, cpu); 34946b44003eSAndrew Morton wake_up_process(sub_thread); 34956b44003eSAndrew Morton wait_for_completion(&wfc.completion); 34962d3854a3SRusty Russell return wfc.ret; 34972d3854a3SRusty Russell } 34982d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 34992d3854a3SRusty Russell #endif /* CONFIG_SMP */ 35002d3854a3SRusty Russell 3501a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3502e7577c50SRusty Russell 3503a0a1a5fdSTejun Heo /** 3504a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3505a0a1a5fdSTejun Heo * 3506a0a1a5fdSTejun Heo * Start freezing workqueues. After this function returns, all 3507a0a1a5fdSTejun Heo * freezeable workqueues will queue new works to their frozen_works 35087e11629dSTejun Heo * list instead of gcwq->worklist. 3509a0a1a5fdSTejun Heo * 3510a0a1a5fdSTejun Heo * CONTEXT: 35118b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3512a0a1a5fdSTejun Heo */ 3513a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3514a0a1a5fdSTejun Heo { 3515a0a1a5fdSTejun Heo unsigned int cpu; 3516a0a1a5fdSTejun Heo 3517a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3518a0a1a5fdSTejun Heo 3519a0a1a5fdSTejun Heo BUG_ON(workqueue_freezing); 3520a0a1a5fdSTejun Heo workqueue_freezing = true; 3521a0a1a5fdSTejun Heo 3522f3421797STejun Heo for_each_gcwq_cpu(cpu) { 35238b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3524bdbc5dd7STejun Heo struct workqueue_struct *wq; 35258b03ae3cSTejun Heo 35268b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 35278b03ae3cSTejun Heo 3528db7bccf4STejun Heo BUG_ON(gcwq->flags & GCWQ_FREEZING); 3529db7bccf4STejun Heo gcwq->flags |= GCWQ_FREEZING; 3530db7bccf4STejun Heo 3531a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3532a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3533a0a1a5fdSTejun Heo 3534f3421797STejun Heo if (cwq && wq->flags & WQ_FREEZEABLE) 3535a0a1a5fdSTejun Heo cwq->max_active = 0; 35361da177e4SLinus Torvalds } 35378b03ae3cSTejun Heo 35388b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3539a0a1a5fdSTejun Heo } 3540a0a1a5fdSTejun Heo 3541a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3542a0a1a5fdSTejun Heo } 3543a0a1a5fdSTejun Heo 3544a0a1a5fdSTejun Heo /** 3545a0a1a5fdSTejun Heo * freeze_workqueues_busy - are freezeable workqueues still busy? 3546a0a1a5fdSTejun Heo * 3547a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3548a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3549a0a1a5fdSTejun Heo * 3550a0a1a5fdSTejun Heo * CONTEXT: 3551a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3552a0a1a5fdSTejun Heo * 3553a0a1a5fdSTejun Heo * RETURNS: 3554a0a1a5fdSTejun Heo * %true if some freezeable workqueues are still busy. %false if 3555a0a1a5fdSTejun Heo * freezing is complete. 3556a0a1a5fdSTejun Heo */ 3557a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3558a0a1a5fdSTejun Heo { 3559a0a1a5fdSTejun Heo unsigned int cpu; 3560a0a1a5fdSTejun Heo bool busy = false; 3561a0a1a5fdSTejun Heo 3562a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3563a0a1a5fdSTejun Heo 3564a0a1a5fdSTejun Heo BUG_ON(!workqueue_freezing); 3565a0a1a5fdSTejun Heo 3566f3421797STejun Heo for_each_gcwq_cpu(cpu) { 3567bdbc5dd7STejun Heo struct workqueue_struct *wq; 3568a0a1a5fdSTejun Heo /* 3569a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3570a0a1a5fdSTejun Heo * to peek without lock. 3571a0a1a5fdSTejun Heo */ 3572a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3573a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3574a0a1a5fdSTejun Heo 3575f3421797STejun Heo if (!cwq || !(wq->flags & WQ_FREEZEABLE)) 3576a0a1a5fdSTejun Heo continue; 3577a0a1a5fdSTejun Heo 3578a0a1a5fdSTejun Heo BUG_ON(cwq->nr_active < 0); 3579a0a1a5fdSTejun Heo if (cwq->nr_active) { 3580a0a1a5fdSTejun Heo busy = true; 3581a0a1a5fdSTejun Heo goto out_unlock; 3582a0a1a5fdSTejun Heo } 3583a0a1a5fdSTejun Heo } 3584a0a1a5fdSTejun Heo } 3585a0a1a5fdSTejun Heo out_unlock: 3586a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3587a0a1a5fdSTejun Heo return busy; 3588a0a1a5fdSTejun Heo } 3589a0a1a5fdSTejun Heo 3590a0a1a5fdSTejun Heo /** 3591a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3592a0a1a5fdSTejun Heo * 3593a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 35947e11629dSTejun Heo * frozen works are transferred to their respective gcwq worklists. 3595a0a1a5fdSTejun Heo * 3596a0a1a5fdSTejun Heo * CONTEXT: 35978b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3598a0a1a5fdSTejun Heo */ 3599a0a1a5fdSTejun Heo void thaw_workqueues(void) 3600a0a1a5fdSTejun Heo { 3601a0a1a5fdSTejun Heo unsigned int cpu; 3602a0a1a5fdSTejun Heo 3603a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3604a0a1a5fdSTejun Heo 3605a0a1a5fdSTejun Heo if (!workqueue_freezing) 3606a0a1a5fdSTejun Heo goto out_unlock; 3607a0a1a5fdSTejun Heo 3608f3421797STejun Heo for_each_gcwq_cpu(cpu) { 36098b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3610bdbc5dd7STejun Heo struct workqueue_struct *wq; 36118b03ae3cSTejun Heo 36128b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 36138b03ae3cSTejun Heo 3614db7bccf4STejun Heo BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); 3615db7bccf4STejun Heo gcwq->flags &= ~GCWQ_FREEZING; 3616db7bccf4STejun Heo 3617a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3618a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3619a0a1a5fdSTejun Heo 3620f3421797STejun Heo if (!cwq || !(wq->flags & WQ_FREEZEABLE)) 3621a0a1a5fdSTejun Heo continue; 3622a0a1a5fdSTejun Heo 3623a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 3624a0a1a5fdSTejun Heo cwq->max_active = wq->saved_max_active; 3625a0a1a5fdSTejun Heo 3626a0a1a5fdSTejun Heo while (!list_empty(&cwq->delayed_works) && 3627a0a1a5fdSTejun Heo cwq->nr_active < cwq->max_active) 3628a0a1a5fdSTejun Heo cwq_activate_first_delayed(cwq); 3629a0a1a5fdSTejun Heo } 36308b03ae3cSTejun Heo 3631e22bee78STejun Heo wake_up_worker(gcwq); 3632e22bee78STejun Heo 36338b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3634a0a1a5fdSTejun Heo } 3635a0a1a5fdSTejun Heo 3636a0a1a5fdSTejun Heo workqueue_freezing = false; 3637a0a1a5fdSTejun Heo out_unlock: 3638a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3639a0a1a5fdSTejun Heo } 3640a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3641a0a1a5fdSTejun Heo 36426ee0578bSSuresh Siddha static int __init init_workqueues(void) 36431da177e4SLinus Torvalds { 3644c34056a3STejun Heo unsigned int cpu; 3645c8e55f36STejun Heo int i; 3646c34056a3STejun Heo 3647f6500947STejun Heo cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); 36488b03ae3cSTejun Heo 36498b03ae3cSTejun Heo /* initialize gcwqs */ 3650f3421797STejun Heo for_each_gcwq_cpu(cpu) { 36518b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 36528b03ae3cSTejun Heo 36538b03ae3cSTejun Heo spin_lock_init(&gcwq->lock); 36547e11629dSTejun Heo INIT_LIST_HEAD(&gcwq->worklist); 36558b03ae3cSTejun Heo gcwq->cpu = cpu; 3656f3421797STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 36578b03ae3cSTejun Heo 3658c8e55f36STejun Heo INIT_LIST_HEAD(&gcwq->idle_list); 3659c8e55f36STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) 3660c8e55f36STejun Heo INIT_HLIST_HEAD(&gcwq->busy_hash[i]); 3661c8e55f36STejun Heo 3662e22bee78STejun Heo init_timer_deferrable(&gcwq->idle_timer); 3663e22bee78STejun Heo gcwq->idle_timer.function = idle_worker_timeout; 3664e22bee78STejun Heo gcwq->idle_timer.data = (unsigned long)gcwq; 3665e22bee78STejun Heo 3666e22bee78STejun Heo setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, 3667e22bee78STejun Heo (unsigned long)gcwq); 3668e22bee78STejun Heo 36698b03ae3cSTejun Heo ida_init(&gcwq->worker_ida); 3670db7bccf4STejun Heo 3671db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3672db7bccf4STejun Heo init_waitqueue_head(&gcwq->trustee_wait); 36738b03ae3cSTejun Heo } 36748b03ae3cSTejun Heo 3675e22bee78STejun Heo /* create the initial worker */ 3676f3421797STejun Heo for_each_online_gcwq_cpu(cpu) { 3677e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3678e22bee78STejun Heo struct worker *worker; 3679e22bee78STejun Heo 3680477a3c33STejun Heo if (cpu != WORK_CPU_UNBOUND) 3681477a3c33STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3682e22bee78STejun Heo worker = create_worker(gcwq, true); 3683e22bee78STejun Heo BUG_ON(!worker); 3684e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3685e22bee78STejun Heo start_worker(worker); 3686e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3687e22bee78STejun Heo } 3688e22bee78STejun Heo 3689d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 3690d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3691d320c038STejun Heo system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); 3692f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3693f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 3694d320c038STejun Heo BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq); 36956ee0578bSSuresh Siddha return 0; 36961da177e4SLinus Torvalds } 36976ee0578bSSuresh Siddha early_initcall(init_workqueues); 3698