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); 1000cdadf009STejun Heo trace_workqueue_queue_work(cpu, cwq, work); 1001502ca9d8STejun Heo 10024690c4abSTejun Heo BUG_ON(!list_empty(&work->entry)); 10031e19ffc6STejun Heo 100473f53c4aSTejun Heo cwq->nr_in_flight[cwq->work_color]++; 10058a2e8e5dSTejun Heo work_flags = work_color_to_flags(cwq->work_color); 10061e19ffc6STejun Heo 10071e19ffc6STejun Heo if (likely(cwq->nr_active < cwq->max_active)) { 1008cdadf009STejun Heo trace_workqueue_activate_work(work); 10091e19ffc6STejun Heo cwq->nr_active++; 1010649027d7STejun Heo worklist = gcwq_determine_ins_pos(gcwq, cwq); 10118a2e8e5dSTejun Heo } else { 10128a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 10131e19ffc6STejun Heo worklist = &cwq->delayed_works; 10148a2e8e5dSTejun Heo } 10151e19ffc6STejun Heo 10168a2e8e5dSTejun Heo insert_work(cwq, work, worklist, work_flags); 10171e19ffc6STejun Heo 10188b03ae3cSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 10191da177e4SLinus Torvalds } 10201da177e4SLinus Torvalds 10210fcb78c2SRolf Eike Beer /** 10220fcb78c2SRolf Eike Beer * queue_work - queue work on a workqueue 10230fcb78c2SRolf Eike Beer * @wq: workqueue to use 10240fcb78c2SRolf Eike Beer * @work: work to queue 10250fcb78c2SRolf Eike Beer * 1026057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10271da177e4SLinus Torvalds * 102800dfcaf7SOleg Nesterov * We queue the work to the CPU on which it was submitted, but if the CPU dies 102900dfcaf7SOleg Nesterov * it can be processed by another CPU. 10301da177e4SLinus Torvalds */ 10317ad5b3a5SHarvey Harrison int queue_work(struct workqueue_struct *wq, struct work_struct *work) 10321da177e4SLinus Torvalds { 1033ef1ca236SOleg Nesterov int ret; 10341da177e4SLinus Torvalds 1035ef1ca236SOleg Nesterov ret = queue_work_on(get_cpu(), wq, work); 1036a848e3b6SOleg Nesterov put_cpu(); 1037ef1ca236SOleg Nesterov 10381da177e4SLinus Torvalds return ret; 10391da177e4SLinus Torvalds } 1040ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_work); 10411da177e4SLinus Torvalds 1042c1a220e7SZhang Rui /** 1043c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1044c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1045c1a220e7SZhang Rui * @wq: workqueue to use 1046c1a220e7SZhang Rui * @work: work to queue 1047c1a220e7SZhang Rui * 1048c1a220e7SZhang Rui * Returns 0 if @work was already on a queue, non-zero otherwise. 1049c1a220e7SZhang Rui * 1050c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1051c1a220e7SZhang Rui * can't go away. 1052c1a220e7SZhang Rui */ 1053c1a220e7SZhang Rui int 1054c1a220e7SZhang Rui queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) 1055c1a220e7SZhang Rui { 1056c1a220e7SZhang Rui int ret = 0; 1057c1a220e7SZhang Rui 105822df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 10594690c4abSTejun Heo __queue_work(cpu, wq, work); 1060c1a220e7SZhang Rui ret = 1; 1061c1a220e7SZhang Rui } 1062c1a220e7SZhang Rui return ret; 1063c1a220e7SZhang Rui } 1064c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1065c1a220e7SZhang Rui 10666d141c3fSLi Zefan static void delayed_work_timer_fn(unsigned long __data) 10671da177e4SLinus Torvalds { 106852bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 10697a22ad75STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); 10701da177e4SLinus Torvalds 10714690c4abSTejun Heo __queue_work(smp_processor_id(), cwq->wq, &dwork->work); 10721da177e4SLinus Torvalds } 10731da177e4SLinus Torvalds 10740fcb78c2SRolf Eike Beer /** 10750fcb78c2SRolf Eike Beer * queue_delayed_work - queue work on a workqueue after delay 10760fcb78c2SRolf Eike Beer * @wq: workqueue to use 1077af9997e4SRandy Dunlap * @dwork: delayable work to queue 10780fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10790fcb78c2SRolf Eike Beer * 1080057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10810fcb78c2SRolf Eike Beer */ 10827ad5b3a5SHarvey Harrison int queue_delayed_work(struct workqueue_struct *wq, 108352bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 10841da177e4SLinus Torvalds { 108552bad64dSDavid Howells if (delay == 0) 108663bc0362SOleg Nesterov return queue_work(wq, &dwork->work); 10871da177e4SLinus Torvalds 108863bc0362SOleg Nesterov return queue_delayed_work_on(-1, wq, dwork, delay); 10891da177e4SLinus Torvalds } 1090ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work); 10911da177e4SLinus Torvalds 10920fcb78c2SRolf Eike Beer /** 10930fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 10940fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 10950fcb78c2SRolf Eike Beer * @wq: workqueue to use 1096af9997e4SRandy Dunlap * @dwork: work to queue 10970fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10980fcb78c2SRolf Eike Beer * 1099057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 11000fcb78c2SRolf Eike Beer */ 11017a6bc1cdSVenkatesh Pallipadi int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 110252bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 11037a6bc1cdSVenkatesh Pallipadi { 11047a6bc1cdSVenkatesh Pallipadi int ret = 0; 110552bad64dSDavid Howells struct timer_list *timer = &dwork->timer; 110652bad64dSDavid Howells struct work_struct *work = &dwork->work; 11077a6bc1cdSVenkatesh Pallipadi 110822df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 1109c7fc77f7STejun Heo unsigned int lcpu; 11107a22ad75STejun Heo 11117a6bc1cdSVenkatesh Pallipadi BUG_ON(timer_pending(timer)); 11127a6bc1cdSVenkatesh Pallipadi BUG_ON(!list_empty(&work->entry)); 11137a6bc1cdSVenkatesh Pallipadi 11148a3e77ccSAndrew Liu timer_stats_timer_set_start_info(&dwork->timer); 11158a3e77ccSAndrew Liu 11167a22ad75STejun Heo /* 11177a22ad75STejun Heo * This stores cwq for the moment, for the timer_fn. 11187a22ad75STejun Heo * Note that the work's gcwq is preserved to allow 11197a22ad75STejun Heo * reentrance detection for delayed works. 11207a22ad75STejun Heo */ 1121c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1122c7fc77f7STejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 1123c7fc77f7STejun Heo 1124c7fc77f7STejun Heo if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) 1125c7fc77f7STejun Heo lcpu = gcwq->cpu; 1126c7fc77f7STejun Heo else 1127c7fc77f7STejun Heo lcpu = raw_smp_processor_id(); 1128c7fc77f7STejun Heo } else 1129c7fc77f7STejun Heo lcpu = WORK_CPU_UNBOUND; 1130c7fc77f7STejun Heo 11317a22ad75STejun Heo set_work_cwq(work, get_cwq(lcpu, wq), 0); 1132c7fc77f7STejun Heo 11337a6bc1cdSVenkatesh Pallipadi timer->expires = jiffies + delay; 113452bad64dSDavid Howells timer->data = (unsigned long)dwork; 11357a6bc1cdSVenkatesh Pallipadi timer->function = delayed_work_timer_fn; 113663bc0362SOleg Nesterov 113763bc0362SOleg Nesterov if (unlikely(cpu >= 0)) 11387a6bc1cdSVenkatesh Pallipadi add_timer_on(timer, cpu); 113963bc0362SOleg Nesterov else 114063bc0362SOleg Nesterov add_timer(timer); 11417a6bc1cdSVenkatesh Pallipadi ret = 1; 11427a6bc1cdSVenkatesh Pallipadi } 11437a6bc1cdSVenkatesh Pallipadi return ret; 11447a6bc1cdSVenkatesh Pallipadi } 1145ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 11461da177e4SLinus Torvalds 1147c8e55f36STejun Heo /** 1148c8e55f36STejun Heo * worker_enter_idle - enter idle state 1149c8e55f36STejun Heo * @worker: worker which is entering idle state 1150c8e55f36STejun Heo * 1151c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1152c8e55f36STejun Heo * necessary. 1153c8e55f36STejun Heo * 1154c8e55f36STejun Heo * LOCKING: 1155c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1156c8e55f36STejun Heo */ 1157c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 11581da177e4SLinus Torvalds { 1159c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1160c8e55f36STejun Heo 1161c8e55f36STejun Heo BUG_ON(worker->flags & WORKER_IDLE); 1162c8e55f36STejun Heo BUG_ON(!list_empty(&worker->entry) && 1163c8e55f36STejun Heo (worker->hentry.next || worker->hentry.pprev)); 1164c8e55f36STejun Heo 1165cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1166cb444766STejun Heo worker->flags |= WORKER_IDLE; 1167c8e55f36STejun Heo gcwq->nr_idle++; 1168e22bee78STejun Heo worker->last_active = jiffies; 1169c8e55f36STejun Heo 1170c8e55f36STejun Heo /* idle_list is LIFO */ 1171c8e55f36STejun Heo list_add(&worker->entry, &gcwq->idle_list); 1172db7bccf4STejun Heo 1173e22bee78STejun Heo if (likely(!(worker->flags & WORKER_ROGUE))) { 1174e22bee78STejun Heo if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) 1175e22bee78STejun Heo mod_timer(&gcwq->idle_timer, 1176e22bee78STejun Heo jiffies + IDLE_WORKER_TIMEOUT); 1177e22bee78STejun Heo } else 1178db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 1179cb444766STejun Heo 1180cb444766STejun Heo /* sanity check nr_running */ 1181cb444766STejun Heo WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && 1182cb444766STejun Heo atomic_read(get_gcwq_nr_running(gcwq->cpu))); 1183c8e55f36STejun Heo } 1184c8e55f36STejun Heo 1185c8e55f36STejun Heo /** 1186c8e55f36STejun Heo * worker_leave_idle - leave idle state 1187c8e55f36STejun Heo * @worker: worker which is leaving idle state 1188c8e55f36STejun Heo * 1189c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1190c8e55f36STejun Heo * 1191c8e55f36STejun Heo * LOCKING: 1192c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1193c8e55f36STejun Heo */ 1194c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1195c8e55f36STejun Heo { 1196c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1197c8e55f36STejun Heo 1198c8e55f36STejun Heo BUG_ON(!(worker->flags & WORKER_IDLE)); 1199d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1200c8e55f36STejun Heo gcwq->nr_idle--; 1201c8e55f36STejun Heo list_del_init(&worker->entry); 1202c8e55f36STejun Heo } 1203c8e55f36STejun Heo 1204e22bee78STejun Heo /** 1205e22bee78STejun Heo * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq 1206e22bee78STejun Heo * @worker: self 1207e22bee78STejun Heo * 1208e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1209e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1210e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1211e22bee78STejun Heo * guaranteed to execute on the cpu. 1212e22bee78STejun Heo * 1213e22bee78STejun Heo * This function is to be used by rogue workers and rescuers to bind 1214e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1215e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1216e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1217e22bee78STejun Heo * verbatim as it's best effort and blocking and gcwq may be 1218e22bee78STejun Heo * [dis]associated in the meantime. 1219e22bee78STejun Heo * 1220e22bee78STejun Heo * This function tries set_cpus_allowed() and locks gcwq and verifies 1221e22bee78STejun Heo * the binding against GCWQ_DISASSOCIATED which is set during 1222e22bee78STejun Heo * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters 1223e22bee78STejun Heo * idle state or fetches works without dropping lock, it can guarantee 1224e22bee78STejun Heo * the scheduling requirement described in the first paragraph. 1225e22bee78STejun Heo * 1226e22bee78STejun Heo * CONTEXT: 1227e22bee78STejun Heo * Might sleep. Called without any lock but returns with gcwq->lock 1228e22bee78STejun Heo * held. 1229e22bee78STejun Heo * 1230e22bee78STejun Heo * RETURNS: 1231e22bee78STejun Heo * %true if the associated gcwq is online (@worker is successfully 1232e22bee78STejun Heo * bound), %false if offline. 1233e22bee78STejun Heo */ 1234e22bee78STejun Heo static bool worker_maybe_bind_and_lock(struct worker *worker) 1235972fa1c5SNamhyung Kim __acquires(&gcwq->lock) 1236e22bee78STejun Heo { 1237e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1238e22bee78STejun Heo struct task_struct *task = worker->task; 1239e22bee78STejun Heo 1240e22bee78STejun Heo while (true) { 1241e22bee78STejun Heo /* 1242e22bee78STejun Heo * The following call may fail, succeed or succeed 1243e22bee78STejun Heo * without actually migrating the task to the cpu if 1244e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 1245e22bee78STejun Heo * against GCWQ_DISASSOCIATED. 1246e22bee78STejun Heo */ 1247f3421797STejun Heo if (!(gcwq->flags & GCWQ_DISASSOCIATED)) 1248e22bee78STejun Heo set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); 1249e22bee78STejun Heo 1250e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1251e22bee78STejun Heo if (gcwq->flags & GCWQ_DISASSOCIATED) 1252e22bee78STejun Heo return false; 1253e22bee78STejun Heo if (task_cpu(task) == gcwq->cpu && 1254e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1255e22bee78STejun Heo get_cpu_mask(gcwq->cpu))) 1256e22bee78STejun Heo return true; 1257e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1258e22bee78STejun Heo 1259e22bee78STejun Heo /* CPU has come up inbetween, retry migration */ 1260e22bee78STejun Heo cpu_relax(); 1261e22bee78STejun Heo } 1262e22bee78STejun Heo } 1263e22bee78STejun Heo 1264e22bee78STejun Heo /* 1265e22bee78STejun Heo * Function for worker->rebind_work used to rebind rogue busy workers 1266e22bee78STejun Heo * to the associated cpu which is coming back online. This is 1267e22bee78STejun Heo * scheduled by cpu up but can race with other cpu hotplug operations 1268e22bee78STejun Heo * and may be executed twice without intervening cpu down. 1269e22bee78STejun Heo */ 1270e22bee78STejun Heo static void worker_rebind_fn(struct work_struct *work) 1271e22bee78STejun Heo { 1272e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1273e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1274e22bee78STejun Heo 1275e22bee78STejun Heo if (worker_maybe_bind_and_lock(worker)) 1276e22bee78STejun Heo worker_clr_flags(worker, WORKER_REBIND); 1277e22bee78STejun Heo 1278e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1279e22bee78STejun Heo } 1280e22bee78STejun Heo 1281c34056a3STejun Heo static struct worker *alloc_worker(void) 1282c34056a3STejun Heo { 1283c34056a3STejun Heo struct worker *worker; 1284c34056a3STejun Heo 1285c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1286c8e55f36STejun Heo if (worker) { 1287c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1288affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1289e22bee78STejun Heo INIT_WORK(&worker->rebind_work, worker_rebind_fn); 1290e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1291e22bee78STejun Heo worker->flags = WORKER_PREP; 1292c8e55f36STejun Heo } 1293c34056a3STejun Heo return worker; 1294c34056a3STejun Heo } 1295c34056a3STejun Heo 1296c34056a3STejun Heo /** 1297c34056a3STejun Heo * create_worker - create a new workqueue worker 12987e11629dSTejun Heo * @gcwq: gcwq the new worker will belong to 1299c34056a3STejun Heo * @bind: whether to set affinity to @cpu or not 1300c34056a3STejun Heo * 13017e11629dSTejun Heo * Create a new worker which is bound to @gcwq. The returned worker 1302c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1303c34056a3STejun Heo * destroy_worker(). 1304c34056a3STejun Heo * 1305c34056a3STejun Heo * CONTEXT: 1306c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1307c34056a3STejun Heo * 1308c34056a3STejun Heo * RETURNS: 1309c34056a3STejun Heo * Pointer to the newly created worker. 1310c34056a3STejun Heo */ 13117e11629dSTejun Heo static struct worker *create_worker(struct global_cwq *gcwq, bool bind) 1312c34056a3STejun Heo { 1313f3421797STejun Heo bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; 1314c34056a3STejun Heo struct worker *worker = NULL; 1315f3421797STejun Heo int id = -1; 1316c34056a3STejun Heo 13178b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13188b03ae3cSTejun Heo while (ida_get_new(&gcwq->worker_ida, &id)) { 13198b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 13208b03ae3cSTejun Heo if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) 1321c34056a3STejun Heo goto fail; 13228b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1323c34056a3STejun Heo } 13248b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1325c34056a3STejun Heo 1326c34056a3STejun Heo worker = alloc_worker(); 1327c34056a3STejun Heo if (!worker) 1328c34056a3STejun Heo goto fail; 1329c34056a3STejun Heo 13308b03ae3cSTejun Heo worker->gcwq = gcwq; 1331c34056a3STejun Heo worker->id = id; 1332c34056a3STejun Heo 1333f3421797STejun Heo if (!on_unbound_cpu) 1334f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1335f3421797STejun Heo "kworker/%u:%d", gcwq->cpu, id); 1336f3421797STejun Heo else 1337f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1338f3421797STejun Heo "kworker/u:%d", id); 1339c34056a3STejun Heo if (IS_ERR(worker->task)) 1340c34056a3STejun Heo goto fail; 1341c34056a3STejun Heo 1342db7bccf4STejun Heo /* 1343db7bccf4STejun Heo * A rogue worker will become a regular one if CPU comes 1344db7bccf4STejun Heo * online later on. Make sure every worker has 1345db7bccf4STejun Heo * PF_THREAD_BOUND set. 1346db7bccf4STejun Heo */ 1347f3421797STejun Heo if (bind && !on_unbound_cpu) 13488b03ae3cSTejun Heo kthread_bind(worker->task, gcwq->cpu); 1349f3421797STejun Heo else { 1350db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1351f3421797STejun Heo if (on_unbound_cpu) 1352f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1353f3421797STejun Heo } 1354c34056a3STejun Heo 1355c34056a3STejun Heo return worker; 1356c34056a3STejun Heo fail: 1357c34056a3STejun Heo if (id >= 0) { 13588b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13598b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 13608b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1361c34056a3STejun Heo } 1362c34056a3STejun Heo kfree(worker); 1363c34056a3STejun Heo return NULL; 1364c34056a3STejun Heo } 1365c34056a3STejun Heo 1366c34056a3STejun Heo /** 1367c34056a3STejun Heo * start_worker - start a newly created worker 1368c34056a3STejun Heo * @worker: worker to start 1369c34056a3STejun Heo * 1370c8e55f36STejun Heo * Make the gcwq aware of @worker and start it. 1371c34056a3STejun Heo * 1372c34056a3STejun Heo * CONTEXT: 13738b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1374c34056a3STejun Heo */ 1375c34056a3STejun Heo static void start_worker(struct worker *worker) 1376c34056a3STejun Heo { 1377cb444766STejun Heo worker->flags |= WORKER_STARTED; 1378c8e55f36STejun Heo worker->gcwq->nr_workers++; 1379c8e55f36STejun Heo worker_enter_idle(worker); 1380c34056a3STejun Heo wake_up_process(worker->task); 1381c34056a3STejun Heo } 1382c34056a3STejun Heo 1383c34056a3STejun Heo /** 1384c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1385c34056a3STejun Heo * @worker: worker to be destroyed 1386c34056a3STejun Heo * 1387c8e55f36STejun Heo * Destroy @worker and adjust @gcwq stats accordingly. 1388c8e55f36STejun Heo * 1389c8e55f36STejun Heo * CONTEXT: 1390c8e55f36STejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1391c34056a3STejun Heo */ 1392c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1393c34056a3STejun Heo { 13948b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 1395c34056a3STejun Heo int id = worker->id; 1396c34056a3STejun Heo 1397c34056a3STejun Heo /* sanity check frenzy */ 1398c34056a3STejun Heo BUG_ON(worker->current_work); 1399affee4b2STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1400c34056a3STejun Heo 1401c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1402c8e55f36STejun Heo gcwq->nr_workers--; 1403c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1404c8e55f36STejun Heo gcwq->nr_idle--; 1405c8e55f36STejun Heo 1406c8e55f36STejun Heo list_del_init(&worker->entry); 1407cb444766STejun Heo worker->flags |= WORKER_DIE; 1408c8e55f36STejun Heo 1409c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1410c8e55f36STejun Heo 1411c34056a3STejun Heo kthread_stop(worker->task); 1412c34056a3STejun Heo kfree(worker); 1413c34056a3STejun Heo 14148b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 14158b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 1416c34056a3STejun Heo } 1417c34056a3STejun Heo 1418e22bee78STejun Heo static void idle_worker_timeout(unsigned long __gcwq) 1419e22bee78STejun Heo { 1420e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1421e22bee78STejun Heo 1422e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1423e22bee78STejun Heo 1424e22bee78STejun Heo if (too_many_workers(gcwq)) { 1425e22bee78STejun Heo struct worker *worker; 1426e22bee78STejun Heo unsigned long expires; 1427e22bee78STejun Heo 1428e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 1429e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1430e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1431e22bee78STejun Heo 1432e22bee78STejun Heo if (time_before(jiffies, expires)) 1433e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1434e22bee78STejun Heo else { 1435e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 1436e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 1437e22bee78STejun Heo wake_up_worker(gcwq); 1438e22bee78STejun Heo } 1439e22bee78STejun Heo } 1440e22bee78STejun Heo 1441e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1442e22bee78STejun Heo } 1443e22bee78STejun Heo 1444e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1445e22bee78STejun Heo { 1446e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1447e22bee78STejun Heo struct workqueue_struct *wq = cwq->wq; 1448f3421797STejun Heo unsigned int cpu; 1449e22bee78STejun Heo 1450e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1451e22bee78STejun Heo return false; 1452e22bee78STejun Heo 1453e22bee78STejun Heo /* mayday mayday mayday */ 1454f3421797STejun Heo cpu = cwq->gcwq->cpu; 1455f3421797STejun Heo /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1456f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 1457f3421797STejun Heo cpu = 0; 1458f2e005aaSTejun Heo if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) 1459e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1460e22bee78STejun Heo return true; 1461e22bee78STejun Heo } 1462e22bee78STejun Heo 1463e22bee78STejun Heo static void gcwq_mayday_timeout(unsigned long __gcwq) 1464e22bee78STejun Heo { 1465e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1466e22bee78STejun Heo struct work_struct *work; 1467e22bee78STejun Heo 1468e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1469e22bee78STejun Heo 1470e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 1471e22bee78STejun Heo /* 1472e22bee78STejun Heo * We've been trying to create a new worker but 1473e22bee78STejun Heo * haven't been successful. We might be hitting an 1474e22bee78STejun Heo * allocation deadlock. Send distress signals to 1475e22bee78STejun Heo * rescuers. 1476e22bee78STejun Heo */ 1477e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) 1478e22bee78STejun Heo send_mayday(work); 1479e22bee78STejun Heo } 1480e22bee78STejun Heo 1481e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1482e22bee78STejun Heo 1483e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); 1484e22bee78STejun Heo } 1485e22bee78STejun Heo 1486e22bee78STejun Heo /** 1487e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 1488e22bee78STejun Heo * @gcwq: gcwq to create a new worker for 1489e22bee78STejun Heo * 1490e22bee78STejun Heo * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to 1491e22bee78STejun Heo * have at least one idle worker on return from this function. If 1492e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 1493e22bee78STejun Heo * sent to all rescuers with works scheduled on @gcwq to resolve 1494e22bee78STejun Heo * possible allocation deadlock. 1495e22bee78STejun Heo * 1496e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1497e22bee78STejun Heo * may_start_working() true. 1498e22bee78STejun Heo * 1499e22bee78STejun Heo * LOCKING: 1500e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1501e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1502e22bee78STejun Heo * manager. 1503e22bee78STejun Heo * 1504e22bee78STejun Heo * RETURNS: 1505e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1506e22bee78STejun Heo * otherwise. 1507e22bee78STejun Heo */ 1508e22bee78STejun Heo static bool maybe_create_worker(struct global_cwq *gcwq) 150906bd6ebfSNamhyung Kim __releases(&gcwq->lock) 151006bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 1511e22bee78STejun Heo { 1512e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1513e22bee78STejun Heo return false; 1514e22bee78STejun Heo restart: 15159f9c2364STejun Heo spin_unlock_irq(&gcwq->lock); 15169f9c2364STejun Heo 1517e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 1518e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1519e22bee78STejun Heo 1520e22bee78STejun Heo while (true) { 1521e22bee78STejun Heo struct worker *worker; 1522e22bee78STejun Heo 1523e22bee78STejun Heo worker = create_worker(gcwq, true); 1524e22bee78STejun Heo if (worker) { 1525e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1526e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1527e22bee78STejun Heo start_worker(worker); 1528e22bee78STejun Heo BUG_ON(need_to_create_worker(gcwq)); 1529e22bee78STejun Heo return true; 1530e22bee78STejun Heo } 1531e22bee78STejun Heo 1532e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1533e22bee78STejun Heo break; 1534e22bee78STejun Heo 1535e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1536e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 15379f9c2364STejun Heo 1538e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1539e22bee78STejun Heo break; 1540e22bee78STejun Heo } 1541e22bee78STejun Heo 1542e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1543e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1544e22bee78STejun Heo if (need_to_create_worker(gcwq)) 1545e22bee78STejun Heo goto restart; 1546e22bee78STejun Heo return true; 1547e22bee78STejun Heo } 1548e22bee78STejun Heo 1549e22bee78STejun Heo /** 1550e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 1551e22bee78STejun Heo * @gcwq: gcwq to destroy workers for 1552e22bee78STejun Heo * 1553e22bee78STejun Heo * Destroy @gcwq workers which have been idle for longer than 1554e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1555e22bee78STejun Heo * 1556e22bee78STejun Heo * LOCKING: 1557e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1558e22bee78STejun Heo * multiple times. Called only from manager. 1559e22bee78STejun Heo * 1560e22bee78STejun Heo * RETURNS: 1561e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1562e22bee78STejun Heo * otherwise. 1563e22bee78STejun Heo */ 1564e22bee78STejun Heo static bool maybe_destroy_workers(struct global_cwq *gcwq) 1565e22bee78STejun Heo { 1566e22bee78STejun Heo bool ret = false; 1567e22bee78STejun Heo 1568e22bee78STejun Heo while (too_many_workers(gcwq)) { 1569e22bee78STejun Heo struct worker *worker; 1570e22bee78STejun Heo unsigned long expires; 1571e22bee78STejun Heo 1572e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1573e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1574e22bee78STejun Heo 1575e22bee78STejun Heo if (time_before(jiffies, expires)) { 1576e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1577e22bee78STejun Heo break; 1578e22bee78STejun Heo } 1579e22bee78STejun Heo 1580e22bee78STejun Heo destroy_worker(worker); 1581e22bee78STejun Heo ret = true; 1582e22bee78STejun Heo } 1583e22bee78STejun Heo 1584e22bee78STejun Heo return ret; 1585e22bee78STejun Heo } 1586e22bee78STejun Heo 1587e22bee78STejun Heo /** 1588e22bee78STejun Heo * manage_workers - manage worker pool 1589e22bee78STejun Heo * @worker: self 1590e22bee78STejun Heo * 1591e22bee78STejun Heo * Assume the manager role and manage gcwq worker pool @worker belongs 1592e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 1593e22bee78STejun Heo * gcwq. The exclusion is handled automatically by this function. 1594e22bee78STejun Heo * 1595e22bee78STejun Heo * The caller can safely start processing works on false return. On 1596e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 1597e22bee78STejun Heo * and may_start_working() is true. 1598e22bee78STejun Heo * 1599e22bee78STejun Heo * CONTEXT: 1600e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1601e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 1602e22bee78STejun Heo * 1603e22bee78STejun Heo * RETURNS: 1604e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true if 1605e22bee78STejun Heo * some action was taken. 1606e22bee78STejun Heo */ 1607e22bee78STejun Heo static bool manage_workers(struct worker *worker) 1608e22bee78STejun Heo { 1609e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1610e22bee78STejun Heo bool ret = false; 1611e22bee78STejun Heo 1612e22bee78STejun Heo if (gcwq->flags & GCWQ_MANAGING_WORKERS) 1613e22bee78STejun Heo return ret; 1614e22bee78STejun Heo 1615e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGE_WORKERS; 1616e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 1617e22bee78STejun Heo 1618e22bee78STejun Heo /* 1619e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 1620e22bee78STejun Heo * on return. 1621e22bee78STejun Heo */ 1622e22bee78STejun Heo ret |= maybe_destroy_workers(gcwq); 1623e22bee78STejun Heo ret |= maybe_create_worker(gcwq); 1624e22bee78STejun Heo 1625e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 1626e22bee78STejun Heo 1627e22bee78STejun Heo /* 1628e22bee78STejun Heo * The trustee might be waiting to take over the manager 1629e22bee78STejun Heo * position, tell it we're done. 1630e22bee78STejun Heo */ 1631e22bee78STejun Heo if (unlikely(gcwq->trustee)) 1632e22bee78STejun Heo wake_up_all(&gcwq->trustee_wait); 1633e22bee78STejun Heo 1634e22bee78STejun Heo return ret; 1635e22bee78STejun Heo } 1636e22bee78STejun Heo 1637a62428c0STejun Heo /** 1638affee4b2STejun Heo * move_linked_works - move linked works to a list 1639affee4b2STejun Heo * @work: start of series of works to be scheduled 1640affee4b2STejun Heo * @head: target list to append @work to 1641affee4b2STejun Heo * @nextp: out paramter for nested worklist walking 1642affee4b2STejun Heo * 1643affee4b2STejun Heo * Schedule linked works starting from @work to @head. Work series to 1644affee4b2STejun Heo * be scheduled starts at @work and includes any consecutive work with 1645affee4b2STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 1646affee4b2STejun Heo * 1647affee4b2STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 1648affee4b2STejun Heo * the last scheduled work. This allows move_linked_works() to be 1649affee4b2STejun Heo * nested inside outer list_for_each_entry_safe(). 1650affee4b2STejun Heo * 1651affee4b2STejun Heo * CONTEXT: 16528b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1653affee4b2STejun Heo */ 1654affee4b2STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1655affee4b2STejun Heo struct work_struct **nextp) 1656affee4b2STejun Heo { 1657affee4b2STejun Heo struct work_struct *n; 1658affee4b2STejun Heo 1659affee4b2STejun Heo /* 1660affee4b2STejun Heo * Linked worklist will always end before the end of the list, 1661affee4b2STejun Heo * use NULL for list head. 1662affee4b2STejun Heo */ 1663affee4b2STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1664affee4b2STejun Heo list_move_tail(&work->entry, head); 1665affee4b2STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1666affee4b2STejun Heo break; 1667affee4b2STejun Heo } 1668affee4b2STejun Heo 1669affee4b2STejun Heo /* 1670affee4b2STejun Heo * If we're already inside safe list traversal and have moved 1671affee4b2STejun Heo * multiple works to the scheduled queue, the next position 1672affee4b2STejun Heo * needs to be updated. 1673affee4b2STejun Heo */ 1674affee4b2STejun Heo if (nextp) 1675affee4b2STejun Heo *nextp = n; 1676affee4b2STejun Heo } 1677affee4b2STejun Heo 16781e19ffc6STejun Heo static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) 16791e19ffc6STejun Heo { 16801e19ffc6STejun Heo struct work_struct *work = list_first_entry(&cwq->delayed_works, 16811da177e4SLinus Torvalds struct work_struct, entry); 1682649027d7STejun Heo struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); 16831e19ffc6STejun Heo 1684cdadf009STejun Heo trace_workqueue_activate_work(work); 1685649027d7STejun Heo move_linked_works(work, pos, NULL); 16868a2e8e5dSTejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 16871e19ffc6STejun Heo cwq->nr_active++; 16881e19ffc6STejun Heo } 16891e19ffc6STejun Heo 1690affee4b2STejun Heo /** 169173f53c4aSTejun Heo * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight 169273f53c4aSTejun Heo * @cwq: cwq of interest 169373f53c4aSTejun Heo * @color: color of work which left the queue 16948a2e8e5dSTejun Heo * @delayed: for a delayed work 169573f53c4aSTejun Heo * 169673f53c4aSTejun Heo * A work either has completed or is removed from pending queue, 169773f53c4aSTejun Heo * decrement nr_in_flight of its cwq and handle workqueue flushing. 169873f53c4aSTejun Heo * 169973f53c4aSTejun Heo * CONTEXT: 17008b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 170173f53c4aSTejun Heo */ 17028a2e8e5dSTejun Heo static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, 17038a2e8e5dSTejun Heo bool delayed) 170473f53c4aSTejun Heo { 170573f53c4aSTejun Heo /* ignore uncolored works */ 170673f53c4aSTejun Heo if (color == WORK_NO_COLOR) 170773f53c4aSTejun Heo return; 170873f53c4aSTejun Heo 170973f53c4aSTejun Heo cwq->nr_in_flight[color]--; 17101e19ffc6STejun Heo 17118a2e8e5dSTejun Heo if (!delayed) { 17128a2e8e5dSTejun Heo cwq->nr_active--; 1713502ca9d8STejun Heo if (!list_empty(&cwq->delayed_works)) { 17141e19ffc6STejun Heo /* one down, submit a delayed one */ 1715502ca9d8STejun Heo if (cwq->nr_active < cwq->max_active) 17161e19ffc6STejun Heo cwq_activate_first_delayed(cwq); 1717502ca9d8STejun Heo } 17188a2e8e5dSTejun Heo } 171973f53c4aSTejun Heo 172073f53c4aSTejun Heo /* is flush in progress and are we at the flushing tip? */ 172173f53c4aSTejun Heo if (likely(cwq->flush_color != color)) 172273f53c4aSTejun Heo return; 172373f53c4aSTejun Heo 172473f53c4aSTejun Heo /* are there still in-flight works? */ 172573f53c4aSTejun Heo if (cwq->nr_in_flight[color]) 172673f53c4aSTejun Heo return; 172773f53c4aSTejun Heo 172873f53c4aSTejun Heo /* this cwq is done, clear flush_color */ 172973f53c4aSTejun Heo cwq->flush_color = -1; 173073f53c4aSTejun Heo 173173f53c4aSTejun Heo /* 173273f53c4aSTejun Heo * If this was the last cwq, wake up the first flusher. It 173373f53c4aSTejun Heo * will handle the rest. 173473f53c4aSTejun Heo */ 173573f53c4aSTejun Heo if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) 173673f53c4aSTejun Heo complete(&cwq->wq->first_flusher->done); 173773f53c4aSTejun Heo } 173873f53c4aSTejun Heo 173973f53c4aSTejun Heo /** 1740a62428c0STejun Heo * process_one_work - process single work 1741c34056a3STejun Heo * @worker: self 1742a62428c0STejun Heo * @work: work to process 1743a62428c0STejun Heo * 1744a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 1745a62428c0STejun Heo * process a single work including synchronization against and 1746a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 1747a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 1748a62428c0STejun Heo * call this function to process a work. 1749a62428c0STejun Heo * 1750a62428c0STejun Heo * CONTEXT: 17518b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1752a62428c0STejun Heo */ 1753c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 175406bd6ebfSNamhyung Kim __releases(&gcwq->lock) 175506bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 17561da177e4SLinus Torvalds { 17577e11629dSTejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 17588b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 1759c8e55f36STejun Heo struct hlist_head *bwh = busy_worker_head(gcwq, work); 1760fb0e7bebSTejun Heo bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 17616bb49e59SDavid Howells work_func_t f = work->func; 176273f53c4aSTejun Heo int work_color; 17637e11629dSTejun Heo struct worker *collision; 17644e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 17654e6045f1SJohannes Berg /* 1766a62428c0STejun Heo * It is permissible to free the struct work_struct from 1767a62428c0STejun Heo * inside the function that is called from it, this we need to 1768a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 1769a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 1770a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 17714e6045f1SJohannes Berg */ 17724e6045f1SJohannes Berg struct lockdep_map lockdep_map = work->lockdep_map; 17734e6045f1SJohannes Berg #endif 17747e11629dSTejun Heo /* 17757e11629dSTejun Heo * A single work shouldn't be executed concurrently by 17767e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 17777e11629dSTejun Heo * already processing the work. If so, defer the work to the 17787e11629dSTejun Heo * currently executing one. 17797e11629dSTejun Heo */ 17807e11629dSTejun Heo collision = __find_worker_executing_work(gcwq, bwh, work); 17817e11629dSTejun Heo if (unlikely(collision)) { 17827e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 17837e11629dSTejun Heo return; 17847e11629dSTejun Heo } 17851da177e4SLinus Torvalds 1786a62428c0STejun Heo /* claim and process */ 17871da177e4SLinus Torvalds debug_work_deactivate(work); 1788c8e55f36STejun Heo hlist_add_head(&worker->hentry, bwh); 1789c34056a3STejun Heo worker->current_work = work; 17908cca0eeaSTejun Heo worker->current_cwq = cwq; 179173f53c4aSTejun Heo work_color = get_work_color(work); 17927a22ad75STejun Heo 17937a22ad75STejun Heo /* record the current cpu number in the work data and dequeue */ 17947a22ad75STejun Heo set_work_cpu(work, gcwq->cpu); 1795a62428c0STejun Heo list_del_init(&work->entry); 1796a62428c0STejun Heo 1797649027d7STejun Heo /* 1798649027d7STejun Heo * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, 1799649027d7STejun Heo * wake up another worker; otherwise, clear HIGHPRI_PENDING. 1800649027d7STejun Heo */ 1801649027d7STejun Heo if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { 1802649027d7STejun Heo struct work_struct *nwork = list_first_entry(&gcwq->worklist, 1803649027d7STejun Heo struct work_struct, entry); 1804649027d7STejun Heo 1805649027d7STejun Heo if (!list_empty(&gcwq->worklist) && 1806649027d7STejun Heo get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) 1807649027d7STejun Heo wake_up_worker(gcwq); 1808649027d7STejun Heo else 1809649027d7STejun Heo gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; 1810649027d7STejun Heo } 1811649027d7STejun Heo 1812fb0e7bebSTejun Heo /* 1813fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 1814fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 1815fb0e7bebSTejun Heo */ 1816fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1817fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 1818fb0e7bebSTejun Heo 18198b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 18201da177e4SLinus Torvalds 182123b2e599SOleg Nesterov work_clear_pending(work); 18223295f0efSIngo Molnar lock_map_acquire(&cwq->wq->lockdep_map); 18233295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 1824e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 182565f27f38SDavid Howells f(work); 1826e36c886aSArjan van de Ven /* 1827e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 1828e36c886aSArjan van de Ven * point will only record its address. 1829e36c886aSArjan van de Ven */ 1830e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 18313295f0efSIngo Molnar lock_map_release(&lockdep_map); 18323295f0efSIngo Molnar lock_map_release(&cwq->wq->lockdep_map); 18331da177e4SLinus Torvalds 1834d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 1835d5abe669SPeter Zijlstra printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " 1836d5abe669SPeter Zijlstra "%s/0x%08x/%d\n", 1837a62428c0STejun Heo current->comm, preempt_count(), task_pid_nr(current)); 1838d5abe669SPeter Zijlstra printk(KERN_ERR " last function: "); 1839d5abe669SPeter Zijlstra print_symbol("%s\n", (unsigned long)f); 1840d5abe669SPeter Zijlstra debug_show_held_locks(current); 1841d5abe669SPeter Zijlstra dump_stack(); 1842d5abe669SPeter Zijlstra } 1843d5abe669SPeter Zijlstra 18448b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1845a62428c0STejun Heo 1846fb0e7bebSTejun Heo /* clear cpu intensive status */ 1847fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1848fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 1849fb0e7bebSTejun Heo 1850a62428c0STejun Heo /* we're done with it, release */ 1851c8e55f36STejun Heo hlist_del_init(&worker->hentry); 1852c34056a3STejun Heo worker->current_work = NULL; 18538cca0eeaSTejun Heo worker->current_cwq = NULL; 18548a2e8e5dSTejun Heo cwq_dec_nr_in_flight(cwq, work_color, false); 18551da177e4SLinus Torvalds } 18561da177e4SLinus Torvalds 1857affee4b2STejun Heo /** 1858affee4b2STejun Heo * process_scheduled_works - process scheduled works 1859affee4b2STejun Heo * @worker: self 1860affee4b2STejun Heo * 1861affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 1862affee4b2STejun Heo * may change while processing a work, so this function repeatedly 1863affee4b2STejun Heo * fetches a work from the top and executes it. 1864affee4b2STejun Heo * 1865affee4b2STejun Heo * CONTEXT: 18668b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1867affee4b2STejun Heo * multiple times. 1868affee4b2STejun Heo */ 1869affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 18701da177e4SLinus Torvalds { 1871affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 1872affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 1873a62428c0STejun Heo struct work_struct, entry); 1874c34056a3STejun Heo process_one_work(worker, work); 1875a62428c0STejun Heo } 18761da177e4SLinus Torvalds } 18771da177e4SLinus Torvalds 18784690c4abSTejun Heo /** 18794690c4abSTejun Heo * worker_thread - the worker thread function 1880c34056a3STejun Heo * @__worker: self 18814690c4abSTejun Heo * 1882e22bee78STejun Heo * The gcwq worker thread function. There's a single dynamic pool of 1883e22bee78STejun Heo * these per each cpu. These workers process all works regardless of 1884e22bee78STejun Heo * their specific target workqueue. The only exception is works which 1885e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 1886e22bee78STejun Heo * rescuer_thread(). 18874690c4abSTejun Heo */ 1888c34056a3STejun Heo static int worker_thread(void *__worker) 18891da177e4SLinus Torvalds { 1890c34056a3STejun Heo struct worker *worker = __worker; 18918b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 18921da177e4SLinus Torvalds 1893e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 1894e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 1895c8e55f36STejun Heo woke_up: 18968b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1897affee4b2STejun Heo 1898c8e55f36STejun Heo /* DIE can be set only while we're idle, checking here is enough */ 1899c8e55f36STejun Heo if (worker->flags & WORKER_DIE) { 1900c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1901e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 1902c8e55f36STejun Heo return 0; 1903c8e55f36STejun Heo } 1904c8e55f36STejun Heo 1905c8e55f36STejun Heo worker_leave_idle(worker); 1906db7bccf4STejun Heo recheck: 1907e22bee78STejun Heo /* no more worker necessary? */ 1908e22bee78STejun Heo if (!need_more_worker(gcwq)) 1909e22bee78STejun Heo goto sleep; 1910e22bee78STejun Heo 1911e22bee78STejun Heo /* do we need to manage? */ 1912e22bee78STejun Heo if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) 1913e22bee78STejun Heo goto recheck; 1914e22bee78STejun Heo 1915c8e55f36STejun Heo /* 1916c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 1917c8e55f36STejun Heo * preparing to process a work or actually processing it. 1918c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 1919c8e55f36STejun Heo */ 1920c8e55f36STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1921c8e55f36STejun Heo 1922e22bee78STejun Heo /* 1923e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 1924e22bee78STejun Heo * at least one idle worker or that someone else has already 1925e22bee78STejun Heo * assumed the manager role. 1926e22bee78STejun Heo */ 1927e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 1928e22bee78STejun Heo 1929e22bee78STejun Heo do { 1930affee4b2STejun Heo struct work_struct *work = 19317e11629dSTejun Heo list_first_entry(&gcwq->worklist, 1932affee4b2STejun Heo struct work_struct, entry); 1933affee4b2STejun Heo 1934c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 1935affee4b2STejun Heo /* optimization path, not strictly necessary */ 1936affee4b2STejun Heo process_one_work(worker, work); 1937affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 1938affee4b2STejun Heo process_scheduled_works(worker); 1939affee4b2STejun Heo } else { 1940c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 1941affee4b2STejun Heo process_scheduled_works(worker); 1942affee4b2STejun Heo } 1943e22bee78STejun Heo } while (keep_working(gcwq)); 1944affee4b2STejun Heo 1945e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 1946d313dd85STejun Heo sleep: 1947e22bee78STejun Heo if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) 1948e22bee78STejun Heo goto recheck; 1949d313dd85STejun Heo 1950c8e55f36STejun Heo /* 1951e22bee78STejun Heo * gcwq->lock is held and there's no work to process and no 1952e22bee78STejun Heo * need to manage, sleep. Workers are woken up only while 1953e22bee78STejun Heo * holding gcwq->lock or from local cpu, so setting the 1954e22bee78STejun Heo * current state before releasing gcwq->lock is enough to 1955e22bee78STejun Heo * prevent losing any event. 1956c8e55f36STejun Heo */ 1957c8e55f36STejun Heo worker_enter_idle(worker); 1958c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 19598b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 19601da177e4SLinus Torvalds schedule(); 1961c8e55f36STejun Heo goto woke_up; 19621da177e4SLinus Torvalds } 19631da177e4SLinus Torvalds 1964e22bee78STejun Heo /** 1965e22bee78STejun Heo * rescuer_thread - the rescuer thread function 1966e22bee78STejun Heo * @__wq: the associated workqueue 1967e22bee78STejun Heo * 1968e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 1969e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 1970e22bee78STejun Heo * 1971e22bee78STejun Heo * Regular work processing on a gcwq may block trying to create a new 1972e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 1973e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 1974e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 1975e22bee78STejun Heo * the problem rescuer solves. 1976e22bee78STejun Heo * 1977e22bee78STejun Heo * When such condition is possible, the gcwq summons rescuers of all 1978e22bee78STejun Heo * workqueues which have works queued on the gcwq and let them process 1979e22bee78STejun Heo * those works so that forward progress can be guaranteed. 1980e22bee78STejun Heo * 1981e22bee78STejun Heo * This should happen rarely. 1982e22bee78STejun Heo */ 1983e22bee78STejun Heo static int rescuer_thread(void *__wq) 1984e22bee78STejun Heo { 1985e22bee78STejun Heo struct workqueue_struct *wq = __wq; 1986e22bee78STejun Heo struct worker *rescuer = wq->rescuer; 1987e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 1988f3421797STejun Heo bool is_unbound = wq->flags & WQ_UNBOUND; 1989e22bee78STejun Heo unsigned int cpu; 1990e22bee78STejun Heo 1991e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 1992e22bee78STejun Heo repeat: 1993e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 19941da177e4SLinus Torvalds 19951da177e4SLinus Torvalds if (kthread_should_stop()) 1996e22bee78STejun Heo return 0; 19971da177e4SLinus Torvalds 1998f3421797STejun Heo /* 1999f3421797STejun Heo * See whether any cpu is asking for help. Unbounded 2000f3421797STejun Heo * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. 2001f3421797STejun Heo */ 2002f2e005aaSTejun Heo for_each_mayday_cpu(cpu, wq->mayday_mask) { 2003f3421797STejun Heo unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 2004f3421797STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); 2005e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 2006e22bee78STejun Heo struct work_struct *work, *n; 2007e22bee78STejun Heo 2008e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2009f2e005aaSTejun Heo mayday_clear_cpu(cpu, wq->mayday_mask); 2010e22bee78STejun Heo 2011e22bee78STejun Heo /* migrate to the target cpu if possible */ 2012e22bee78STejun Heo rescuer->gcwq = gcwq; 2013e22bee78STejun Heo worker_maybe_bind_and_lock(rescuer); 2014e22bee78STejun Heo 2015e22bee78STejun Heo /* 2016e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2017e22bee78STejun Heo * process'em. 2018e22bee78STejun Heo */ 2019e22bee78STejun Heo BUG_ON(!list_empty(&rescuer->scheduled)); 2020e22bee78STejun Heo list_for_each_entry_safe(work, n, &gcwq->worklist, entry) 2021e22bee78STejun Heo if (get_work_cwq(work) == cwq) 2022e22bee78STejun Heo move_linked_works(work, scheduled, &n); 2023e22bee78STejun Heo 2024e22bee78STejun Heo process_scheduled_works(rescuer); 2025e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 20261da177e4SLinus Torvalds } 20271da177e4SLinus Torvalds 2028e22bee78STejun Heo schedule(); 2029e22bee78STejun Heo goto repeat; 20301da177e4SLinus Torvalds } 20311da177e4SLinus Torvalds 2032fc2e4d70SOleg Nesterov struct wq_barrier { 2033fc2e4d70SOleg Nesterov struct work_struct work; 2034fc2e4d70SOleg Nesterov struct completion done; 2035fc2e4d70SOleg Nesterov }; 2036fc2e4d70SOleg Nesterov 2037fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2038fc2e4d70SOleg Nesterov { 2039fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2040fc2e4d70SOleg Nesterov complete(&barr->done); 2041fc2e4d70SOleg Nesterov } 2042fc2e4d70SOleg Nesterov 20434690c4abSTejun Heo /** 20444690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 20454690c4abSTejun Heo * @cwq: cwq to insert barrier into 20464690c4abSTejun Heo * @barr: wq_barrier to insert 2047affee4b2STejun Heo * @target: target work to attach @barr to 2048affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 20494690c4abSTejun Heo * 2050affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2051affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2052affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2053affee4b2STejun Heo * cpu. 2054affee4b2STejun Heo * 2055affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2056affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2057affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2058affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2059affee4b2STejun Heo * after a work with LINKED flag set. 2060affee4b2STejun Heo * 2061affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2062affee4b2STejun Heo * underneath us, so we can't reliably determine cwq from @target. 20634690c4abSTejun Heo * 20644690c4abSTejun Heo * CONTEXT: 20658b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 20664690c4abSTejun Heo */ 206783c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 2068affee4b2STejun Heo struct wq_barrier *barr, 2069affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2070fc2e4d70SOleg Nesterov { 2071affee4b2STejun Heo struct list_head *head; 2072affee4b2STejun Heo unsigned int linked = 0; 2073affee4b2STejun Heo 2074dc186ad7SThomas Gleixner /* 20758b03ae3cSTejun Heo * debugobject calls are safe here even with gcwq->lock locked 2076dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2077dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2078dc186ad7SThomas Gleixner * might deadlock. 2079dc186ad7SThomas Gleixner */ 2080dc186ad7SThomas Gleixner INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); 208122df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2082fc2e4d70SOleg Nesterov init_completion(&barr->done); 208383c22520SOleg Nesterov 2084affee4b2STejun Heo /* 2085affee4b2STejun Heo * If @target is currently being executed, schedule the 2086affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2087affee4b2STejun Heo */ 2088affee4b2STejun Heo if (worker) 2089affee4b2STejun Heo head = worker->scheduled.next; 2090affee4b2STejun Heo else { 2091affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2092affee4b2STejun Heo 2093affee4b2STejun Heo head = target->entry.next; 2094affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2095affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2096affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2097affee4b2STejun Heo } 2098affee4b2STejun Heo 2099dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2100affee4b2STejun Heo insert_work(cwq, &barr->work, head, 2101affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2102fc2e4d70SOleg Nesterov } 2103fc2e4d70SOleg Nesterov 210473f53c4aSTejun Heo /** 210573f53c4aSTejun Heo * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing 210673f53c4aSTejun Heo * @wq: workqueue being flushed 210773f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 210873f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 210973f53c4aSTejun Heo * 211073f53c4aSTejun Heo * Prepare cwqs for workqueue flushing. 211173f53c4aSTejun Heo * 211273f53c4aSTejun Heo * If @flush_color is non-negative, flush_color on all cwqs should be 211373f53c4aSTejun Heo * -1. If no cwq has in-flight commands at the specified color, all 211473f53c4aSTejun Heo * cwq->flush_color's stay at -1 and %false is returned. If any cwq 211573f53c4aSTejun Heo * has in flight commands, its cwq->flush_color is set to 211673f53c4aSTejun Heo * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq 211773f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 211873f53c4aSTejun Heo * 211973f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 212073f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 212173f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 212273f53c4aSTejun Heo * is returned. 212373f53c4aSTejun Heo * 212473f53c4aSTejun Heo * If @work_color is non-negative, all cwqs should have the same 212573f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 212673f53c4aSTejun Heo * advanced to @work_color. 212773f53c4aSTejun Heo * 212873f53c4aSTejun Heo * CONTEXT: 212973f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 213073f53c4aSTejun Heo * 213173f53c4aSTejun Heo * RETURNS: 213273f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 213373f53c4aSTejun Heo * otherwise. 213473f53c4aSTejun Heo */ 213573f53c4aSTejun Heo static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, 213673f53c4aSTejun Heo int flush_color, int work_color) 21371da177e4SLinus Torvalds { 213873f53c4aSTejun Heo bool wait = false; 213973f53c4aSTejun Heo unsigned int cpu; 21401da177e4SLinus Torvalds 214173f53c4aSTejun Heo if (flush_color >= 0) { 214273f53c4aSTejun Heo BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); 214373f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 1); 2144dc186ad7SThomas Gleixner } 214514441960SOleg Nesterov 2146f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 214773f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 21488b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 21491da177e4SLinus Torvalds 21508b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 215173f53c4aSTejun Heo 215273f53c4aSTejun Heo if (flush_color >= 0) { 215373f53c4aSTejun Heo BUG_ON(cwq->flush_color != -1); 215473f53c4aSTejun Heo 215573f53c4aSTejun Heo if (cwq->nr_in_flight[flush_color]) { 215673f53c4aSTejun Heo cwq->flush_color = flush_color; 215773f53c4aSTejun Heo atomic_inc(&wq->nr_cwqs_to_flush); 215873f53c4aSTejun Heo wait = true; 21591da177e4SLinus Torvalds } 216073f53c4aSTejun Heo } 216173f53c4aSTejun Heo 216273f53c4aSTejun Heo if (work_color >= 0) { 216373f53c4aSTejun Heo BUG_ON(work_color != work_next_color(cwq->work_color)); 216473f53c4aSTejun Heo cwq->work_color = work_color; 216573f53c4aSTejun Heo } 216673f53c4aSTejun Heo 21678b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 21681da177e4SLinus Torvalds } 21691da177e4SLinus Torvalds 217073f53c4aSTejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) 217173f53c4aSTejun Heo complete(&wq->first_flusher->done); 217273f53c4aSTejun Heo 217373f53c4aSTejun Heo return wait; 217483c22520SOleg Nesterov } 21751da177e4SLinus Torvalds 21760fcb78c2SRolf Eike Beer /** 21771da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 21780fcb78c2SRolf Eike Beer * @wq: workqueue to flush 21791da177e4SLinus Torvalds * 21801da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 21811da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 21821da177e4SLinus Torvalds * 2183fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2184fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 21851da177e4SLinus Torvalds */ 21867ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 21871da177e4SLinus Torvalds { 218873f53c4aSTejun Heo struct wq_flusher this_flusher = { 218973f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 219073f53c4aSTejun Heo .flush_color = -1, 219173f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 219273f53c4aSTejun Heo }; 219373f53c4aSTejun Heo int next_color; 2194b1f4ec17SOleg Nesterov 21953295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 21963295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 219773f53c4aSTejun Heo 219873f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 219973f53c4aSTejun Heo 220073f53c4aSTejun Heo /* 220173f53c4aSTejun Heo * Start-to-wait phase 220273f53c4aSTejun Heo */ 220373f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 220473f53c4aSTejun Heo 220573f53c4aSTejun Heo if (next_color != wq->flush_color) { 220673f53c4aSTejun Heo /* 220773f53c4aSTejun Heo * Color space is not full. The current work_color 220873f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 220973f53c4aSTejun Heo * by one. 221073f53c4aSTejun Heo */ 221173f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow)); 221273f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 221373f53c4aSTejun Heo wq->work_color = next_color; 221473f53c4aSTejun Heo 221573f53c4aSTejun Heo if (!wq->first_flusher) { 221673f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 221773f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 221873f53c4aSTejun Heo 221973f53c4aSTejun Heo wq->first_flusher = &this_flusher; 222073f53c4aSTejun Heo 222173f53c4aSTejun Heo if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, 222273f53c4aSTejun Heo wq->work_color)) { 222373f53c4aSTejun Heo /* nothing to flush, done */ 222473f53c4aSTejun Heo wq->flush_color = next_color; 222573f53c4aSTejun Heo wq->first_flusher = NULL; 222673f53c4aSTejun Heo goto out_unlock; 222773f53c4aSTejun Heo } 222873f53c4aSTejun Heo } else { 222973f53c4aSTejun Heo /* wait in queue */ 223073f53c4aSTejun Heo BUG_ON(wq->flush_color == this_flusher.flush_color); 223173f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 223273f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 223373f53c4aSTejun Heo } 223473f53c4aSTejun Heo } else { 223573f53c4aSTejun Heo /* 223673f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 223773f53c4aSTejun Heo * The next flush completion will assign us 223873f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 223973f53c4aSTejun Heo */ 224073f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 224173f53c4aSTejun Heo } 224273f53c4aSTejun Heo 224373f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 224473f53c4aSTejun Heo 224573f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 224673f53c4aSTejun Heo 224773f53c4aSTejun Heo /* 224873f53c4aSTejun Heo * Wake-up-and-cascade phase 224973f53c4aSTejun Heo * 225073f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 225173f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 225273f53c4aSTejun Heo */ 225373f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 225473f53c4aSTejun Heo return; 225573f53c4aSTejun Heo 225673f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 225773f53c4aSTejun Heo 22584ce48b37STejun Heo /* we might have raced, check again with mutex held */ 22594ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 22604ce48b37STejun Heo goto out_unlock; 22614ce48b37STejun Heo 226273f53c4aSTejun Heo wq->first_flusher = NULL; 226373f53c4aSTejun Heo 226473f53c4aSTejun Heo BUG_ON(!list_empty(&this_flusher.list)); 226573f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 226673f53c4aSTejun Heo 226773f53c4aSTejun Heo while (true) { 226873f53c4aSTejun Heo struct wq_flusher *next, *tmp; 226973f53c4aSTejun Heo 227073f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 227173f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 227273f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 227373f53c4aSTejun Heo break; 227473f53c4aSTejun Heo list_del_init(&next->list); 227573f53c4aSTejun Heo complete(&next->done); 227673f53c4aSTejun Heo } 227773f53c4aSTejun Heo 227873f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow) && 227973f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 228073f53c4aSTejun Heo 228173f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 228273f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 228373f53c4aSTejun Heo 228473f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 228573f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 228673f53c4aSTejun Heo /* 228773f53c4aSTejun Heo * Assign the same color to all overflowed 228873f53c4aSTejun Heo * flushers, advance work_color and append to 228973f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 229073f53c4aSTejun Heo * phase for these overflowed flushers. 229173f53c4aSTejun Heo */ 229273f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 229373f53c4aSTejun Heo tmp->flush_color = wq->work_color; 229473f53c4aSTejun Heo 229573f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 229673f53c4aSTejun Heo 229773f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 229873f53c4aSTejun Heo &wq->flusher_queue); 229973f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 230073f53c4aSTejun Heo } 230173f53c4aSTejun Heo 230273f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 230373f53c4aSTejun Heo BUG_ON(wq->flush_color != wq->work_color); 230473f53c4aSTejun Heo break; 230573f53c4aSTejun Heo } 230673f53c4aSTejun Heo 230773f53c4aSTejun Heo /* 230873f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 230973f53c4aSTejun Heo * the new first flusher and arm cwqs. 231073f53c4aSTejun Heo */ 231173f53c4aSTejun Heo BUG_ON(wq->flush_color == wq->work_color); 231273f53c4aSTejun Heo BUG_ON(wq->flush_color != next->flush_color); 231373f53c4aSTejun Heo 231473f53c4aSTejun Heo list_del_init(&next->list); 231573f53c4aSTejun Heo wq->first_flusher = next; 231673f53c4aSTejun Heo 231773f53c4aSTejun Heo if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) 231873f53c4aSTejun Heo break; 231973f53c4aSTejun Heo 232073f53c4aSTejun Heo /* 232173f53c4aSTejun Heo * Meh... this color is already done, clear first 232273f53c4aSTejun Heo * flusher and repeat cascading. 232373f53c4aSTejun Heo */ 232473f53c4aSTejun Heo wq->first_flusher = NULL; 232573f53c4aSTejun Heo } 232673f53c4aSTejun Heo 232773f53c4aSTejun Heo out_unlock: 232873f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 23291da177e4SLinus Torvalds } 2330ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 23311da177e4SLinus Torvalds 2332baf59022STejun Heo static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, 2333baf59022STejun Heo bool wait_executing) 2334baf59022STejun Heo { 2335baf59022STejun Heo struct worker *worker = NULL; 2336baf59022STejun Heo struct global_cwq *gcwq; 2337baf59022STejun Heo struct cpu_workqueue_struct *cwq; 2338baf59022STejun Heo 2339baf59022STejun Heo might_sleep(); 2340baf59022STejun Heo gcwq = get_work_gcwq(work); 2341baf59022STejun Heo if (!gcwq) 2342baf59022STejun Heo return false; 2343baf59022STejun Heo 2344baf59022STejun Heo spin_lock_irq(&gcwq->lock); 2345baf59022STejun Heo if (!list_empty(&work->entry)) { 2346baf59022STejun Heo /* 2347baf59022STejun Heo * See the comment near try_to_grab_pending()->smp_rmb(). 2348baf59022STejun Heo * If it was re-queued to a different gcwq under us, we 2349baf59022STejun Heo * are not going to wait. 2350baf59022STejun Heo */ 2351baf59022STejun Heo smp_rmb(); 2352baf59022STejun Heo cwq = get_work_cwq(work); 2353baf59022STejun Heo if (unlikely(!cwq || gcwq != cwq->gcwq)) 2354baf59022STejun Heo goto already_gone; 2355baf59022STejun Heo } else if (wait_executing) { 2356baf59022STejun Heo worker = find_worker_executing_work(gcwq, work); 2357baf59022STejun Heo if (!worker) 2358baf59022STejun Heo goto already_gone; 2359baf59022STejun Heo cwq = worker->current_cwq; 2360baf59022STejun Heo } else 2361baf59022STejun Heo goto already_gone; 2362baf59022STejun Heo 2363baf59022STejun Heo insert_wq_barrier(cwq, barr, work, worker); 2364baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2365baf59022STejun Heo 2366baf59022STejun Heo lock_map_acquire(&cwq->wq->lockdep_map); 2367baf59022STejun Heo lock_map_release(&cwq->wq->lockdep_map); 2368baf59022STejun Heo return true; 2369baf59022STejun Heo already_gone: 2370baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2371baf59022STejun Heo return false; 2372baf59022STejun Heo } 2373baf59022STejun Heo 2374db700897SOleg Nesterov /** 2375401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 2376401a8d04STejun Heo * @work: the work to flush 2377db700897SOleg Nesterov * 2378401a8d04STejun Heo * Wait until @work has finished execution. This function considers 2379401a8d04STejun Heo * only the last queueing instance of @work. If @work has been 2380401a8d04STejun Heo * enqueued across different CPUs on a non-reentrant workqueue or on 2381401a8d04STejun Heo * multiple workqueues, @work might still be executing on return on 2382401a8d04STejun Heo * some of the CPUs from earlier queueing. 2383a67da70dSOleg Nesterov * 2384401a8d04STejun Heo * If @work was queued only on a non-reentrant, ordered or unbound 2385401a8d04STejun Heo * workqueue, @work is guaranteed to be idle on return if it hasn't 2386401a8d04STejun Heo * been requeued since flush started. 2387401a8d04STejun Heo * 2388401a8d04STejun Heo * RETURNS: 2389401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2390401a8d04STejun Heo * %false if it was already idle. 2391db700897SOleg Nesterov */ 2392401a8d04STejun Heo bool flush_work(struct work_struct *work) 2393db700897SOleg Nesterov { 2394db700897SOleg Nesterov struct wq_barrier barr; 2395db700897SOleg Nesterov 2396baf59022STejun Heo if (start_flush_work(work, &barr, true)) { 2397db700897SOleg Nesterov wait_for_completion(&barr.done); 2398dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2399401a8d04STejun Heo return true; 2400baf59022STejun Heo } else 2401401a8d04STejun Heo return false; 2402db700897SOleg Nesterov } 2403db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2404db700897SOleg Nesterov 2405401a8d04STejun Heo static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) 2406401a8d04STejun Heo { 2407401a8d04STejun Heo struct wq_barrier barr; 2408401a8d04STejun Heo struct worker *worker; 2409401a8d04STejun Heo 2410401a8d04STejun Heo spin_lock_irq(&gcwq->lock); 2411401a8d04STejun Heo 2412401a8d04STejun Heo worker = find_worker_executing_work(gcwq, work); 2413401a8d04STejun Heo if (unlikely(worker)) 2414401a8d04STejun Heo insert_wq_barrier(worker->current_cwq, &barr, work, worker); 2415401a8d04STejun Heo 2416401a8d04STejun Heo spin_unlock_irq(&gcwq->lock); 2417401a8d04STejun Heo 2418401a8d04STejun Heo if (unlikely(worker)) { 2419401a8d04STejun Heo wait_for_completion(&barr.done); 2420401a8d04STejun Heo destroy_work_on_stack(&barr.work); 2421401a8d04STejun Heo return true; 2422401a8d04STejun Heo } else 2423401a8d04STejun Heo return false; 2424401a8d04STejun Heo } 2425401a8d04STejun Heo 2426401a8d04STejun Heo static bool wait_on_work(struct work_struct *work) 2427401a8d04STejun Heo { 2428401a8d04STejun Heo bool ret = false; 2429401a8d04STejun Heo int cpu; 2430401a8d04STejun Heo 2431401a8d04STejun Heo might_sleep(); 2432401a8d04STejun Heo 2433401a8d04STejun Heo lock_map_acquire(&work->lockdep_map); 2434401a8d04STejun Heo lock_map_release(&work->lockdep_map); 2435401a8d04STejun Heo 2436401a8d04STejun Heo for_each_gcwq_cpu(cpu) 2437401a8d04STejun Heo ret |= wait_on_cpu_work(get_gcwq(cpu), work); 2438401a8d04STejun Heo return ret; 2439401a8d04STejun Heo } 2440401a8d04STejun Heo 244109383498STejun Heo /** 244209383498STejun Heo * flush_work_sync - wait until a work has finished execution 244309383498STejun Heo * @work: the work to flush 244409383498STejun Heo * 244509383498STejun Heo * Wait until @work has finished execution. On return, it's 244609383498STejun Heo * guaranteed that all queueing instances of @work which happened 244709383498STejun Heo * before this function is called are finished. In other words, if 244809383498STejun Heo * @work hasn't been requeued since this function was called, @work is 244909383498STejun Heo * guaranteed to be idle on return. 245009383498STejun Heo * 245109383498STejun Heo * RETURNS: 245209383498STejun Heo * %true if flush_work_sync() waited for the work to finish execution, 245309383498STejun Heo * %false if it was already idle. 245409383498STejun Heo */ 245509383498STejun Heo bool flush_work_sync(struct work_struct *work) 245609383498STejun Heo { 245709383498STejun Heo struct wq_barrier barr; 245809383498STejun Heo bool pending, waited; 245909383498STejun Heo 246009383498STejun Heo /* we'll wait for executions separately, queue barr only if pending */ 246109383498STejun Heo pending = start_flush_work(work, &barr, false); 246209383498STejun Heo 246309383498STejun Heo /* wait for executions to finish */ 246409383498STejun Heo waited = wait_on_work(work); 246509383498STejun Heo 246609383498STejun Heo /* wait for the pending one */ 246709383498STejun Heo if (pending) { 246809383498STejun Heo wait_for_completion(&barr.done); 246909383498STejun Heo destroy_work_on_stack(&barr.work); 247009383498STejun Heo } 247109383498STejun Heo 247209383498STejun Heo return pending || waited; 247309383498STejun Heo } 247409383498STejun Heo EXPORT_SYMBOL_GPL(flush_work_sync); 247509383498STejun Heo 24766e84d644SOleg Nesterov /* 24771f1f642eSOleg Nesterov * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, 24786e84d644SOleg Nesterov * so this work can't be re-armed in any way. 24796e84d644SOleg Nesterov */ 24806e84d644SOleg Nesterov static int try_to_grab_pending(struct work_struct *work) 24816e84d644SOleg Nesterov { 24828b03ae3cSTejun Heo struct global_cwq *gcwq; 24831f1f642eSOleg Nesterov int ret = -1; 24846e84d644SOleg Nesterov 248522df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 24861f1f642eSOleg Nesterov return 0; 24876e84d644SOleg Nesterov 24886e84d644SOleg Nesterov /* 24896e84d644SOleg Nesterov * The queueing is in progress, or it is already queued. Try to 24906e84d644SOleg Nesterov * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 24916e84d644SOleg Nesterov */ 24927a22ad75STejun Heo gcwq = get_work_gcwq(work); 24937a22ad75STejun Heo if (!gcwq) 24946e84d644SOleg Nesterov return ret; 24956e84d644SOleg Nesterov 24968b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 24976e84d644SOleg Nesterov if (!list_empty(&work->entry)) { 24986e84d644SOleg Nesterov /* 24997a22ad75STejun Heo * This work is queued, but perhaps we locked the wrong gcwq. 25006e84d644SOleg Nesterov * In that case we must see the new value after rmb(), see 25016e84d644SOleg Nesterov * insert_work()->wmb(). 25026e84d644SOleg Nesterov */ 25036e84d644SOleg Nesterov smp_rmb(); 25047a22ad75STejun Heo if (gcwq == get_work_gcwq(work)) { 2505dc186ad7SThomas Gleixner debug_work_deactivate(work); 25066e84d644SOleg Nesterov list_del_init(&work->entry); 25077a22ad75STejun Heo cwq_dec_nr_in_flight(get_work_cwq(work), 25088a2e8e5dSTejun Heo get_work_color(work), 25098a2e8e5dSTejun Heo *work_data_bits(work) & WORK_STRUCT_DELAYED); 25106e84d644SOleg Nesterov ret = 1; 25116e84d644SOleg Nesterov } 25126e84d644SOleg Nesterov } 25138b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 25146e84d644SOleg Nesterov 25156e84d644SOleg Nesterov return ret; 25166e84d644SOleg Nesterov } 25176e84d644SOleg Nesterov 2518401a8d04STejun Heo static bool __cancel_work_timer(struct work_struct *work, 25191f1f642eSOleg Nesterov struct timer_list* timer) 25201f1f642eSOleg Nesterov { 25211f1f642eSOleg Nesterov int ret; 25221f1f642eSOleg Nesterov 25231f1f642eSOleg Nesterov do { 25241f1f642eSOleg Nesterov ret = (timer && likely(del_timer(timer))); 25251f1f642eSOleg Nesterov if (!ret) 25261f1f642eSOleg Nesterov ret = try_to_grab_pending(work); 25271f1f642eSOleg Nesterov wait_on_work(work); 25281f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 25291f1f642eSOleg Nesterov 25307a22ad75STejun Heo clear_work_data(work); 25311f1f642eSOleg Nesterov return ret; 25321f1f642eSOleg Nesterov } 25331f1f642eSOleg Nesterov 25346e84d644SOleg Nesterov /** 2535401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 2536401a8d04STejun Heo * @work: the work to cancel 25376e84d644SOleg Nesterov * 2538401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 2539401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 2540401a8d04STejun Heo * another workqueue. On return from this function, @work is 2541401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 25421f1f642eSOleg Nesterov * 2543401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 2544401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 25456e84d644SOleg Nesterov * 2546401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 25476e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 2548401a8d04STejun Heo * 2549401a8d04STejun Heo * RETURNS: 2550401a8d04STejun Heo * %true if @work was pending, %false otherwise. 25516e84d644SOleg Nesterov */ 2552401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 25536e84d644SOleg Nesterov { 25541f1f642eSOleg Nesterov return __cancel_work_timer(work, NULL); 2555b89deed3SOleg Nesterov } 255628e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2557b89deed3SOleg Nesterov 25586e84d644SOleg Nesterov /** 2559401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 2560401a8d04STejun Heo * @dwork: the delayed work to flush 25616e84d644SOleg Nesterov * 2562401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 2563401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 2564401a8d04STejun Heo * considers the last queueing instance of @dwork. 25651f1f642eSOleg Nesterov * 2566401a8d04STejun Heo * RETURNS: 2567401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2568401a8d04STejun Heo * %false if it was already idle. 25696e84d644SOleg Nesterov */ 2570401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 2571401a8d04STejun Heo { 2572401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 2573401a8d04STejun Heo __queue_work(raw_smp_processor_id(), 2574401a8d04STejun Heo get_work_cwq(&dwork->work)->wq, &dwork->work); 2575401a8d04STejun Heo return flush_work(&dwork->work); 2576401a8d04STejun Heo } 2577401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 2578401a8d04STejun Heo 2579401a8d04STejun Heo /** 258009383498STejun Heo * flush_delayed_work_sync - wait for a dwork to finish 258109383498STejun Heo * @dwork: the delayed work to flush 258209383498STejun Heo * 258309383498STejun Heo * Delayed timer is cancelled and the pending work is queued for 258409383498STejun Heo * execution immediately. Other than timer handling, its behavior 258509383498STejun Heo * is identical to flush_work_sync(). 258609383498STejun Heo * 258709383498STejun Heo * RETURNS: 258809383498STejun Heo * %true if flush_work_sync() waited for the work to finish execution, 258909383498STejun Heo * %false if it was already idle. 259009383498STejun Heo */ 259109383498STejun Heo bool flush_delayed_work_sync(struct delayed_work *dwork) 259209383498STejun Heo { 259309383498STejun Heo if (del_timer_sync(&dwork->timer)) 259409383498STejun Heo __queue_work(raw_smp_processor_id(), 259509383498STejun Heo get_work_cwq(&dwork->work)->wq, &dwork->work); 259609383498STejun Heo return flush_work_sync(&dwork->work); 259709383498STejun Heo } 259809383498STejun Heo EXPORT_SYMBOL(flush_delayed_work_sync); 259909383498STejun Heo 260009383498STejun Heo /** 2601401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 2602401a8d04STejun Heo * @dwork: the delayed work cancel 2603401a8d04STejun Heo * 2604401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 2605401a8d04STejun Heo * 2606401a8d04STejun Heo * RETURNS: 2607401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 2608401a8d04STejun Heo */ 2609401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 26106e84d644SOleg Nesterov { 26111f1f642eSOleg Nesterov return __cancel_work_timer(&dwork->work, &dwork->timer); 26126e84d644SOleg Nesterov } 2613f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 26141da177e4SLinus Torvalds 26150fcb78c2SRolf Eike Beer /** 26160fcb78c2SRolf Eike Beer * schedule_work - put work task in global workqueue 26170fcb78c2SRolf Eike Beer * @work: job to be done 26180fcb78c2SRolf Eike Beer * 26195b0f437dSBart Van Assche * Returns zero if @work was already on the kernel-global workqueue and 26205b0f437dSBart Van Assche * non-zero otherwise. 26215b0f437dSBart Van Assche * 26225b0f437dSBart Van Assche * This puts a job in the kernel-global workqueue if it was not already 26235b0f437dSBart Van Assche * queued and leaves it in the same position on the kernel-global 26245b0f437dSBart Van Assche * workqueue otherwise. 26250fcb78c2SRolf Eike Beer */ 26267ad5b3a5SHarvey Harrison int schedule_work(struct work_struct *work) 26271da177e4SLinus Torvalds { 2628d320c038STejun Heo return queue_work(system_wq, work); 26291da177e4SLinus Torvalds } 2630ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_work); 26311da177e4SLinus Torvalds 2632c1a220e7SZhang Rui /* 2633c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2634c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2635c1a220e7SZhang Rui * @work: job to be done 2636c1a220e7SZhang Rui * 2637c1a220e7SZhang Rui * This puts a job on a specific cpu 2638c1a220e7SZhang Rui */ 2639c1a220e7SZhang Rui int schedule_work_on(int cpu, struct work_struct *work) 2640c1a220e7SZhang Rui { 2641d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 2642c1a220e7SZhang Rui } 2643c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 2644c1a220e7SZhang Rui 26450fcb78c2SRolf Eike Beer /** 26460fcb78c2SRolf Eike Beer * schedule_delayed_work - put work task in global workqueue after delay 264752bad64dSDavid Howells * @dwork: job to be done 264852bad64dSDavid Howells * @delay: number of jiffies to wait or 0 for immediate execution 26490fcb78c2SRolf Eike Beer * 26500fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 26510fcb78c2SRolf Eike Beer * workqueue. 26520fcb78c2SRolf Eike Beer */ 26537ad5b3a5SHarvey Harrison int schedule_delayed_work(struct delayed_work *dwork, 265482f67cd9SIngo Molnar unsigned long delay) 26551da177e4SLinus Torvalds { 2656d320c038STejun Heo return queue_delayed_work(system_wq, dwork, delay); 26571da177e4SLinus Torvalds } 2658ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work); 26591da177e4SLinus Torvalds 26600fcb78c2SRolf Eike Beer /** 26610fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 26620fcb78c2SRolf Eike Beer * @cpu: cpu to use 266352bad64dSDavid Howells * @dwork: job to be done 26640fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 26650fcb78c2SRolf Eike Beer * 26660fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 26670fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 26680fcb78c2SRolf Eike Beer */ 26691da177e4SLinus Torvalds int schedule_delayed_work_on(int cpu, 267052bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 26711da177e4SLinus Torvalds { 2672d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 26731da177e4SLinus Torvalds } 2674ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 26751da177e4SLinus Torvalds 2676b6136773SAndrew Morton /** 2677b6136773SAndrew Morton * schedule_on_each_cpu - call a function on each online CPU from keventd 2678b6136773SAndrew Morton * @func: the function to call 2679b6136773SAndrew Morton * 2680b6136773SAndrew Morton * Returns zero on success. 2681b6136773SAndrew Morton * Returns -ve errno on failure. 2682b6136773SAndrew Morton * 2683b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 2684b6136773SAndrew Morton */ 268565f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 268615316ba8SChristoph Lameter { 268715316ba8SChristoph Lameter int cpu; 268838f51568SNamhyung Kim struct work_struct __percpu *works; 268915316ba8SChristoph Lameter 2690b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 2691b6136773SAndrew Morton if (!works) 269215316ba8SChristoph Lameter return -ENOMEM; 2693b6136773SAndrew Morton 269495402b38SGautham R Shenoy get_online_cpus(); 269593981800STejun Heo 269615316ba8SChristoph Lameter for_each_online_cpu(cpu) { 26979bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 26989bfb1839SIngo Molnar 26999bfb1839SIngo Molnar INIT_WORK(work, func); 27008de6d308SOleg Nesterov schedule_work_on(cpu, work); 270115316ba8SChristoph Lameter } 270293981800STejun Heo 270393981800STejun Heo for_each_online_cpu(cpu) 27048616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 270593981800STejun Heo 270695402b38SGautham R Shenoy put_online_cpus(); 2707b6136773SAndrew Morton free_percpu(works); 270815316ba8SChristoph Lameter return 0; 270915316ba8SChristoph Lameter } 271015316ba8SChristoph Lameter 2711eef6a7d5SAlan Stern /** 2712eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 2713eef6a7d5SAlan Stern * 2714eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 2715eef6a7d5SAlan Stern * completion. 2716eef6a7d5SAlan Stern * 2717eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 2718eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 2719eef6a7d5SAlan Stern * will lead to deadlock: 2720eef6a7d5SAlan Stern * 2721eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 2722eef6a7d5SAlan Stern * a lock held by your code or its caller. 2723eef6a7d5SAlan Stern * 2724eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 2725eef6a7d5SAlan Stern * 2726eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 2727eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 2728eef6a7d5SAlan Stern * what locks they need, which you have no control over. 2729eef6a7d5SAlan Stern * 2730eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 2731eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 2732eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 2733eef6a7d5SAlan Stern * cancel_work_sync() instead. 2734eef6a7d5SAlan Stern */ 27351da177e4SLinus Torvalds void flush_scheduled_work(void) 27361da177e4SLinus Torvalds { 2737d320c038STejun Heo flush_workqueue(system_wq); 27381da177e4SLinus Torvalds } 2739ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 27401da177e4SLinus Torvalds 27411da177e4SLinus Torvalds /** 27421fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 27431fa44ecaSJames Bottomley * @fn: the function to execute 27441fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 27451fa44ecaSJames Bottomley * be available when the work executes) 27461fa44ecaSJames Bottomley * 27471fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 27481fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 27491fa44ecaSJames Bottomley * 27501fa44ecaSJames Bottomley * Returns: 0 - function was executed 27511fa44ecaSJames Bottomley * 1 - function was scheduled for execution 27521fa44ecaSJames Bottomley */ 275365f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 27541fa44ecaSJames Bottomley { 27551fa44ecaSJames Bottomley if (!in_interrupt()) { 275665f27f38SDavid Howells fn(&ew->work); 27571fa44ecaSJames Bottomley return 0; 27581fa44ecaSJames Bottomley } 27591fa44ecaSJames Bottomley 276065f27f38SDavid Howells INIT_WORK(&ew->work, fn); 27611fa44ecaSJames Bottomley schedule_work(&ew->work); 27621fa44ecaSJames Bottomley 27631fa44ecaSJames Bottomley return 1; 27641fa44ecaSJames Bottomley } 27651fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 27661fa44ecaSJames Bottomley 27671da177e4SLinus Torvalds int keventd_up(void) 27681da177e4SLinus Torvalds { 2769d320c038STejun Heo return system_wq != NULL; 27701da177e4SLinus Torvalds } 27711da177e4SLinus Torvalds 2772bdbc5dd7STejun Heo static int alloc_cwqs(struct workqueue_struct *wq) 27731da177e4SLinus Torvalds { 27743af24433SOleg Nesterov /* 27750f900049STejun Heo * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. 27760f900049STejun Heo * Make sure that the alignment isn't lower than that of 27770f900049STejun Heo * unsigned long long. 27783af24433SOleg Nesterov */ 27790f900049STejun Heo const size_t size = sizeof(struct cpu_workqueue_struct); 27800f900049STejun Heo const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, 27810f900049STejun Heo __alignof__(unsigned long long)); 2782931ac77eSTejun Heo #ifdef CONFIG_SMP 2783931ac77eSTejun Heo bool percpu = !(wq->flags & WQ_UNBOUND); 2784931ac77eSTejun Heo #else 2785931ac77eSTejun Heo bool percpu = false; 2786931ac77eSTejun Heo #endif 27873af24433SOleg Nesterov 2788931ac77eSTejun Heo if (percpu) 2789f3421797STejun Heo wq->cpu_wq.pcpu = __alloc_percpu(size, align); 2790931ac77eSTejun Heo else { 27910f900049STejun Heo void *ptr; 2792e1d8aa9fSFrederic Weisbecker 27930f900049STejun Heo /* 2794f3421797STejun Heo * Allocate enough room to align cwq and put an extra 2795f3421797STejun Heo * pointer at the end pointing back to the originally 2796f3421797STejun Heo * allocated pointer which will be used for free. 27970f900049STejun Heo */ 2798bdbc5dd7STejun Heo ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); 2799bdbc5dd7STejun Heo if (ptr) { 2800bdbc5dd7STejun Heo wq->cpu_wq.single = PTR_ALIGN(ptr, align); 2801bdbc5dd7STejun Heo *(void **)(wq->cpu_wq.single + 1) = ptr; 2802bdbc5dd7STejun Heo } 28033af24433SOleg Nesterov } 28043af24433SOleg Nesterov 28050f900049STejun Heo /* just in case, make sure it's actually aligned */ 2806bdbc5dd7STejun Heo BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); 2807bdbc5dd7STejun Heo return wq->cpu_wq.v ? 0 : -ENOMEM; 28080f900049STejun Heo } 28090f900049STejun Heo 2810bdbc5dd7STejun Heo static void free_cwqs(struct workqueue_struct *wq) 281106ba38a9SOleg Nesterov { 2812931ac77eSTejun Heo #ifdef CONFIG_SMP 2813931ac77eSTejun Heo bool percpu = !(wq->flags & WQ_UNBOUND); 2814931ac77eSTejun Heo #else 2815931ac77eSTejun Heo bool percpu = false; 2816931ac77eSTejun Heo #endif 281706ba38a9SOleg Nesterov 2818931ac77eSTejun Heo if (percpu) 2819bdbc5dd7STejun Heo free_percpu(wq->cpu_wq.pcpu); 2820f3421797STejun Heo else if (wq->cpu_wq.single) { 2821f3421797STejun Heo /* the pointer to free is stored right after the cwq */ 2822f3421797STejun Heo kfree(*(void **)(wq->cpu_wq.single + 1)); 282306ba38a9SOleg Nesterov } 282406ba38a9SOleg Nesterov } 282506ba38a9SOleg Nesterov 2826f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 2827f3421797STejun Heo const char *name) 2828b71ab8c2STejun Heo { 2829f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 2830f3421797STejun Heo 2831f3421797STejun Heo if (max_active < 1 || max_active > lim) 2832b71ab8c2STejun Heo printk(KERN_WARNING "workqueue: max_active %d requested for %s " 2833b71ab8c2STejun Heo "is out of range, clamping between %d and %d\n", 2834f3421797STejun Heo max_active, name, 1, lim); 2835b71ab8c2STejun Heo 2836f3421797STejun Heo return clamp_val(max_active, 1, lim); 2837b71ab8c2STejun Heo } 2838b71ab8c2STejun Heo 2839d320c038STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *name, 284097e37d7bSTejun Heo unsigned int flags, 28411e19ffc6STejun Heo int max_active, 2842eb13ba87SJohannes Berg struct lock_class_key *key, 2843eb13ba87SJohannes Berg const char *lock_name) 28443af24433SOleg Nesterov { 28453af24433SOleg Nesterov struct workqueue_struct *wq; 2846c34056a3STejun Heo unsigned int cpu; 28473af24433SOleg Nesterov 2848f3421797STejun Heo /* 2849f3421797STejun Heo * Unbound workqueues aren't concurrency managed and should be 2850f3421797STejun Heo * dispatched to workers immediately. 2851f3421797STejun Heo */ 2852f3421797STejun Heo if (flags & WQ_UNBOUND) 2853f3421797STejun Heo flags |= WQ_HIGHPRI; 2854f3421797STejun Heo 2855d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 2856f3421797STejun Heo max_active = wq_clamp_max_active(max_active, flags, name); 28573af24433SOleg Nesterov 28583af24433SOleg Nesterov wq = kzalloc(sizeof(*wq), GFP_KERNEL); 28593af24433SOleg Nesterov if (!wq) 28604690c4abSTejun Heo goto err; 28613af24433SOleg Nesterov 286297e37d7bSTejun Heo wq->flags = flags; 2863a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 286473f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 286573f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 0); 286673f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 286773f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 28683af24433SOleg Nesterov 28693af24433SOleg Nesterov wq->name = name; 2870eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 2871cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 28723af24433SOleg Nesterov 2873bdbc5dd7STejun Heo if (alloc_cwqs(wq) < 0) 2874bdbc5dd7STejun Heo goto err; 2875bdbc5dd7STejun Heo 2876f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 28771537663fSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 28788b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 28791537663fSTejun Heo 28800f900049STejun Heo BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 28818b03ae3cSTejun Heo cwq->gcwq = gcwq; 2882c34056a3STejun Heo cwq->wq = wq; 288373f53c4aSTejun Heo cwq->flush_color = -1; 28841e19ffc6STejun Heo cwq->max_active = max_active; 28851e19ffc6STejun Heo INIT_LIST_HEAD(&cwq->delayed_works); 2886e22bee78STejun Heo } 28871537663fSTejun Heo 2888e22bee78STejun Heo if (flags & WQ_RESCUER) { 2889e22bee78STejun Heo struct worker *rescuer; 2890e22bee78STejun Heo 2891f2e005aaSTejun Heo if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) 2892e22bee78STejun Heo goto err; 2893e22bee78STejun Heo 2894e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 2895e22bee78STejun Heo if (!rescuer) 2896e22bee78STejun Heo goto err; 2897e22bee78STejun Heo 2898e22bee78STejun Heo rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); 2899e22bee78STejun Heo if (IS_ERR(rescuer->task)) 2900e22bee78STejun Heo goto err; 2901e22bee78STejun Heo 2902e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 2903e22bee78STejun Heo wake_up_process(rescuer->task); 29043af24433SOleg Nesterov } 29051537663fSTejun Heo 29063af24433SOleg Nesterov /* 2907a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 2908a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 2909a0a1a5fdSTejun Heo * workqueue to workqueues list. 29103af24433SOleg Nesterov */ 29113af24433SOleg Nesterov spin_lock(&workqueue_lock); 2912a0a1a5fdSTejun Heo 2913a0a1a5fdSTejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) 2914f3421797STejun Heo for_each_cwq_cpu(cpu, wq) 2915a0a1a5fdSTejun Heo get_cwq(cpu, wq)->max_active = 0; 2916a0a1a5fdSTejun Heo 29173af24433SOleg Nesterov list_add(&wq->list, &workqueues); 2918a0a1a5fdSTejun Heo 29193af24433SOleg Nesterov spin_unlock(&workqueue_lock); 29203af24433SOleg Nesterov 29213af24433SOleg Nesterov return wq; 29224690c4abSTejun Heo err: 29234690c4abSTejun Heo if (wq) { 2924bdbc5dd7STejun Heo free_cwqs(wq); 2925f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 2926e22bee78STejun Heo kfree(wq->rescuer); 29274690c4abSTejun Heo kfree(wq); 29283af24433SOleg Nesterov } 29294690c4abSTejun Heo return NULL; 29301da177e4SLinus Torvalds } 2931d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 29321da177e4SLinus Torvalds 29333af24433SOleg Nesterov /** 29343af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 29353af24433SOleg Nesterov * @wq: target workqueue 29363af24433SOleg Nesterov * 29373af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 29383af24433SOleg Nesterov */ 29393af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 29403af24433SOleg Nesterov { 2941c8e55f36STejun Heo unsigned int cpu; 29423af24433SOleg Nesterov 2943e41e704bSTejun Heo wq->flags |= WQ_DYING; 2944a0a1a5fdSTejun Heo flush_workqueue(wq); 2945a0a1a5fdSTejun Heo 2946a0a1a5fdSTejun Heo /* 2947a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 2948a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 2949a0a1a5fdSTejun Heo */ 295095402b38SGautham R Shenoy spin_lock(&workqueue_lock); 29513af24433SOleg Nesterov list_del(&wq->list); 295295402b38SGautham R Shenoy spin_unlock(&workqueue_lock); 29533af24433SOleg Nesterov 2954e22bee78STejun Heo /* sanity check */ 2955f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 295673f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 295773f53c4aSTejun Heo int i; 29583af24433SOleg Nesterov 295973f53c4aSTejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 296073f53c4aSTejun Heo BUG_ON(cwq->nr_in_flight[i]); 29611e19ffc6STejun Heo BUG_ON(cwq->nr_active); 29621e19ffc6STejun Heo BUG_ON(!list_empty(&cwq->delayed_works)); 296373f53c4aSTejun Heo } 29641537663fSTejun Heo 2965e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 2966e22bee78STejun Heo kthread_stop(wq->rescuer->task); 2967f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 29688d9df9f0SXiaotian Feng kfree(wq->rescuer); 2969e22bee78STejun Heo } 2970e22bee78STejun Heo 2971bdbc5dd7STejun Heo free_cwqs(wq); 29723af24433SOleg Nesterov kfree(wq); 29733af24433SOleg Nesterov } 29743af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 29753af24433SOleg Nesterov 2976dcd989cbSTejun Heo /** 2977dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 2978dcd989cbSTejun Heo * @wq: target workqueue 2979dcd989cbSTejun Heo * @max_active: new max_active value. 2980dcd989cbSTejun Heo * 2981dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 2982dcd989cbSTejun Heo * 2983dcd989cbSTejun Heo * CONTEXT: 2984dcd989cbSTejun Heo * Don't call from IRQ context. 2985dcd989cbSTejun Heo */ 2986dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 2987dcd989cbSTejun Heo { 2988dcd989cbSTejun Heo unsigned int cpu; 2989dcd989cbSTejun Heo 2990f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 2991dcd989cbSTejun Heo 2992dcd989cbSTejun Heo spin_lock(&workqueue_lock); 2993dcd989cbSTejun Heo 2994dcd989cbSTejun Heo wq->saved_max_active = max_active; 2995dcd989cbSTejun Heo 2996f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 2997dcd989cbSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 2998dcd989cbSTejun Heo 2999dcd989cbSTejun Heo spin_lock_irq(&gcwq->lock); 3000dcd989cbSTejun Heo 3001dcd989cbSTejun Heo if (!(wq->flags & WQ_FREEZEABLE) || 3002dcd989cbSTejun Heo !(gcwq->flags & GCWQ_FREEZING)) 3003dcd989cbSTejun Heo get_cwq(gcwq->cpu, wq)->max_active = max_active; 3004dcd989cbSTejun Heo 3005dcd989cbSTejun Heo spin_unlock_irq(&gcwq->lock); 3006dcd989cbSTejun Heo } 3007dcd989cbSTejun Heo 3008dcd989cbSTejun Heo spin_unlock(&workqueue_lock); 3009dcd989cbSTejun Heo } 3010dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 3011dcd989cbSTejun Heo 3012dcd989cbSTejun Heo /** 3013dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 3014dcd989cbSTejun Heo * @cpu: CPU in question 3015dcd989cbSTejun Heo * @wq: target workqueue 3016dcd989cbSTejun Heo * 3017dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 3018dcd989cbSTejun Heo * no synchronization around this function and the test result is 3019dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3020dcd989cbSTejun Heo * 3021dcd989cbSTejun Heo * RETURNS: 3022dcd989cbSTejun Heo * %true if congested, %false otherwise. 3023dcd989cbSTejun Heo */ 3024dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 3025dcd989cbSTejun Heo { 3026dcd989cbSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3027dcd989cbSTejun Heo 3028dcd989cbSTejun Heo return !list_empty(&cwq->delayed_works); 3029dcd989cbSTejun Heo } 3030dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 3031dcd989cbSTejun Heo 3032dcd989cbSTejun Heo /** 3033dcd989cbSTejun Heo * work_cpu - return the last known associated cpu for @work 3034dcd989cbSTejun Heo * @work: the work of interest 3035dcd989cbSTejun Heo * 3036dcd989cbSTejun Heo * RETURNS: 3037bdbc5dd7STejun Heo * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. 3038dcd989cbSTejun Heo */ 3039dcd989cbSTejun Heo unsigned int work_cpu(struct work_struct *work) 3040dcd989cbSTejun Heo { 3041dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3042dcd989cbSTejun Heo 3043bdbc5dd7STejun Heo return gcwq ? gcwq->cpu : WORK_CPU_NONE; 3044dcd989cbSTejun Heo } 3045dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_cpu); 3046dcd989cbSTejun Heo 3047dcd989cbSTejun Heo /** 3048dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 3049dcd989cbSTejun Heo * @work: the work to be tested 3050dcd989cbSTejun Heo * 3051dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 3052dcd989cbSTejun Heo * synchronization around this function and the test result is 3053dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3054dcd989cbSTejun Heo * Especially for reentrant wqs, the pending state might hide the 3055dcd989cbSTejun Heo * running state. 3056dcd989cbSTejun Heo * 3057dcd989cbSTejun Heo * RETURNS: 3058dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 3059dcd989cbSTejun Heo */ 3060dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 3061dcd989cbSTejun Heo { 3062dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3063dcd989cbSTejun Heo unsigned long flags; 3064dcd989cbSTejun Heo unsigned int ret = 0; 3065dcd989cbSTejun Heo 3066dcd989cbSTejun Heo if (!gcwq) 3067dcd989cbSTejun Heo return false; 3068dcd989cbSTejun Heo 3069dcd989cbSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 3070dcd989cbSTejun Heo 3071dcd989cbSTejun Heo if (work_pending(work)) 3072dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 3073dcd989cbSTejun Heo if (find_worker_executing_work(gcwq, work)) 3074dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 3075dcd989cbSTejun Heo 3076dcd989cbSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 3077dcd989cbSTejun Heo 3078dcd989cbSTejun Heo return ret; 3079dcd989cbSTejun Heo } 3080dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 3081dcd989cbSTejun Heo 3082db7bccf4STejun Heo /* 3083db7bccf4STejun Heo * CPU hotplug. 3084db7bccf4STejun Heo * 3085e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 3086e22bee78STejun Heo * are a lot of assumptions on strong associations among work, cwq and 3087e22bee78STejun Heo * gcwq which make migrating pending and scheduled works very 3088e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 3089e22bee78STejun Heo * gcwqs serve mix of short, long and very long running works making 3090e22bee78STejun Heo * blocked draining impractical. 3091e22bee78STejun Heo * 3092e22bee78STejun Heo * This is solved by allowing a gcwq to be detached from CPU, running 3093e22bee78STejun Heo * it with unbound (rogue) workers and allowing it to be reattached 3094e22bee78STejun Heo * later if the cpu comes back online. A separate thread is created 3095e22bee78STejun Heo * to govern a gcwq in such state and is called the trustee of the 3096e22bee78STejun Heo * gcwq. 3097db7bccf4STejun Heo * 3098db7bccf4STejun Heo * Trustee states and their descriptions. 3099db7bccf4STejun Heo * 3100db7bccf4STejun Heo * START Command state used on startup. On CPU_DOWN_PREPARE, a 3101db7bccf4STejun Heo * new trustee is started with this state. 3102db7bccf4STejun Heo * 3103db7bccf4STejun Heo * IN_CHARGE Once started, trustee will enter this state after 3104e22bee78STejun Heo * assuming the manager role and making all existing 3105e22bee78STejun Heo * workers rogue. DOWN_PREPARE waits for trustee to 3106e22bee78STejun Heo * enter this state. After reaching IN_CHARGE, trustee 3107e22bee78STejun Heo * tries to execute the pending worklist until it's empty 3108e22bee78STejun Heo * and the state is set to BUTCHER, or the state is set 3109e22bee78STejun Heo * to RELEASE. 3110db7bccf4STejun Heo * 3111db7bccf4STejun Heo * BUTCHER Command state which is set by the cpu callback after 3112db7bccf4STejun Heo * the cpu has went down. Once this state is set trustee 3113db7bccf4STejun Heo * knows that there will be no new works on the worklist 3114db7bccf4STejun Heo * and once the worklist is empty it can proceed to 3115db7bccf4STejun Heo * killing idle workers. 3116db7bccf4STejun Heo * 3117db7bccf4STejun Heo * RELEASE Command state which is set by the cpu callback if the 3118db7bccf4STejun Heo * cpu down has been canceled or it has come online 3119db7bccf4STejun Heo * again. After recognizing this state, trustee stops 3120e22bee78STejun Heo * trying to drain or butcher and clears ROGUE, rebinds 3121e22bee78STejun Heo * all remaining workers back to the cpu and releases 3122e22bee78STejun Heo * manager role. 3123db7bccf4STejun Heo * 3124db7bccf4STejun Heo * DONE Trustee will enter this state after BUTCHER or RELEASE 3125db7bccf4STejun Heo * is complete. 3126db7bccf4STejun Heo * 3127db7bccf4STejun Heo * trustee CPU draining 3128db7bccf4STejun Heo * took over down complete 3129db7bccf4STejun Heo * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE 3130db7bccf4STejun Heo * | | ^ 3131db7bccf4STejun Heo * | CPU is back online v return workers | 3132db7bccf4STejun Heo * ----------------> RELEASE -------------- 3133db7bccf4STejun Heo */ 3134db7bccf4STejun Heo 3135db7bccf4STejun Heo /** 3136db7bccf4STejun Heo * trustee_wait_event_timeout - timed event wait for trustee 3137db7bccf4STejun Heo * @cond: condition to wait for 3138db7bccf4STejun Heo * @timeout: timeout in jiffies 3139db7bccf4STejun Heo * 3140db7bccf4STejun Heo * wait_event_timeout() for trustee to use. Handles locking and 3141db7bccf4STejun Heo * checks for RELEASE request. 3142db7bccf4STejun Heo * 3143db7bccf4STejun Heo * CONTEXT: 3144db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3145db7bccf4STejun Heo * multiple times. To be used by trustee. 3146db7bccf4STejun Heo * 3147db7bccf4STejun Heo * RETURNS: 3148db7bccf4STejun Heo * Positive indicating left time if @cond is satisfied, 0 if timed 3149db7bccf4STejun Heo * out, -1 if canceled. 3150db7bccf4STejun Heo */ 3151db7bccf4STejun Heo #define trustee_wait_event_timeout(cond, timeout) ({ \ 3152db7bccf4STejun Heo long __ret = (timeout); \ 3153db7bccf4STejun Heo while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ 3154db7bccf4STejun Heo __ret) { \ 3155db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); \ 3156db7bccf4STejun Heo __wait_event_timeout(gcwq->trustee_wait, (cond) || \ 3157db7bccf4STejun Heo (gcwq->trustee_state == TRUSTEE_RELEASE), \ 3158db7bccf4STejun Heo __ret); \ 3159db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); \ 3160db7bccf4STejun Heo } \ 3161db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ 3162db7bccf4STejun Heo }) 3163db7bccf4STejun Heo 3164db7bccf4STejun Heo /** 3165db7bccf4STejun Heo * trustee_wait_event - event wait for trustee 3166db7bccf4STejun Heo * @cond: condition to wait for 3167db7bccf4STejun Heo * 3168db7bccf4STejun Heo * wait_event() for trustee to use. Automatically handles locking and 3169db7bccf4STejun Heo * checks for CANCEL request. 3170db7bccf4STejun Heo * 3171db7bccf4STejun Heo * CONTEXT: 3172db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3173db7bccf4STejun Heo * multiple times. To be used by trustee. 3174db7bccf4STejun Heo * 3175db7bccf4STejun Heo * RETURNS: 3176db7bccf4STejun Heo * 0 if @cond is satisfied, -1 if canceled. 3177db7bccf4STejun Heo */ 3178db7bccf4STejun Heo #define trustee_wait_event(cond) ({ \ 3179db7bccf4STejun Heo long __ret1; \ 3180db7bccf4STejun Heo __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ 3181db7bccf4STejun Heo __ret1 < 0 ? -1 : 0; \ 3182db7bccf4STejun Heo }) 3183db7bccf4STejun Heo 3184db7bccf4STejun Heo static int __cpuinit trustee_thread(void *__gcwq) 3185db7bccf4STejun Heo { 3186db7bccf4STejun Heo struct global_cwq *gcwq = __gcwq; 3187db7bccf4STejun Heo struct worker *worker; 3188e22bee78STejun Heo struct work_struct *work; 3189db7bccf4STejun Heo struct hlist_node *pos; 3190e22bee78STejun Heo long rc; 3191db7bccf4STejun Heo int i; 3192db7bccf4STejun Heo 3193db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3194db7bccf4STejun Heo 3195db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3196db7bccf4STejun Heo /* 3197e22bee78STejun Heo * Claim the manager position and make all workers rogue. 3198e22bee78STejun Heo * Trustee must be bound to the target cpu and can't be 3199e22bee78STejun Heo * cancelled. 3200db7bccf4STejun Heo */ 3201db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3202e22bee78STejun Heo rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); 3203e22bee78STejun Heo BUG_ON(rc < 0); 3204e22bee78STejun Heo 3205e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 3206db7bccf4STejun Heo 3207db7bccf4STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) 3208cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3209db7bccf4STejun Heo 3210db7bccf4STejun Heo for_each_busy_worker(worker, i, pos, gcwq) 3211cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3212db7bccf4STejun Heo 3213db7bccf4STejun Heo /* 3214e22bee78STejun Heo * Call schedule() so that we cross rq->lock and thus can 3215e22bee78STejun Heo * guarantee sched callbacks see the rogue flag. This is 3216e22bee78STejun Heo * necessary as scheduler callbacks may be invoked from other 3217e22bee78STejun Heo * cpus. 3218e22bee78STejun Heo */ 3219e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3220e22bee78STejun Heo schedule(); 3221e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3222e22bee78STejun Heo 3223e22bee78STejun Heo /* 3224cb444766STejun Heo * Sched callbacks are disabled now. Zap nr_running. After 3225cb444766STejun Heo * this, nr_running stays zero and need_more_worker() and 3226cb444766STejun Heo * keep_working() are always true as long as the worklist is 3227cb444766STejun Heo * not empty. 3228e22bee78STejun Heo */ 3229cb444766STejun Heo atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); 3230e22bee78STejun Heo 3231e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3232e22bee78STejun Heo del_timer_sync(&gcwq->idle_timer); 3233e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3234e22bee78STejun Heo 3235e22bee78STejun Heo /* 3236db7bccf4STejun Heo * We're now in charge. Notify and proceed to drain. We need 3237db7bccf4STejun Heo * to keep the gcwq running during the whole CPU down 3238db7bccf4STejun Heo * procedure as other cpu hotunplug callbacks may need to 3239db7bccf4STejun Heo * flush currently running tasks. 3240db7bccf4STejun Heo */ 3241db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_IN_CHARGE; 3242db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3243db7bccf4STejun Heo 3244db7bccf4STejun Heo /* 3245db7bccf4STejun Heo * The original cpu is in the process of dying and may go away 3246db7bccf4STejun Heo * anytime now. When that happens, we and all workers would 3247e22bee78STejun Heo * be migrated to other cpus. Try draining any left work. We 3248e22bee78STejun Heo * want to get it over with ASAP - spam rescuers, wake up as 3249e22bee78STejun Heo * many idlers as necessary and create new ones till the 3250e22bee78STejun Heo * worklist is empty. Note that if the gcwq is frozen, there 3251e22bee78STejun Heo * may be frozen works in freezeable cwqs. Don't declare 3252e22bee78STejun Heo * completion while frozen. 3253db7bccf4STejun Heo */ 3254db7bccf4STejun Heo while (gcwq->nr_workers != gcwq->nr_idle || 3255db7bccf4STejun Heo gcwq->flags & GCWQ_FREEZING || 3256db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_IN_CHARGE) { 3257e22bee78STejun Heo int nr_works = 0; 3258e22bee78STejun Heo 3259e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) { 3260e22bee78STejun Heo send_mayday(work); 3261e22bee78STejun Heo nr_works++; 3262e22bee78STejun Heo } 3263e22bee78STejun Heo 3264e22bee78STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) { 3265e22bee78STejun Heo if (!nr_works--) 3266e22bee78STejun Heo break; 3267e22bee78STejun Heo wake_up_process(worker->task); 3268e22bee78STejun Heo } 3269e22bee78STejun Heo 3270e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 3271e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3272e22bee78STejun Heo worker = create_worker(gcwq, false); 3273e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3274e22bee78STejun Heo if (worker) { 3275cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3276e22bee78STejun Heo start_worker(worker); 3277e22bee78STejun Heo } 3278e22bee78STejun Heo } 3279e22bee78STejun Heo 3280db7bccf4STejun Heo /* give a breather */ 3281db7bccf4STejun Heo if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) 3282db7bccf4STejun Heo break; 3283db7bccf4STejun Heo } 3284db7bccf4STejun Heo 3285e22bee78STejun Heo /* 3286e22bee78STejun Heo * Either all works have been scheduled and cpu is down, or 3287e22bee78STejun Heo * cpu down has already been canceled. Wait for and butcher 3288e22bee78STejun Heo * all workers till we're canceled. 3289e22bee78STejun Heo */ 3290e22bee78STejun Heo do { 3291e22bee78STejun Heo rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); 3292e22bee78STejun Heo while (!list_empty(&gcwq->idle_list)) 3293e22bee78STejun Heo destroy_worker(list_first_entry(&gcwq->idle_list, 3294e22bee78STejun Heo struct worker, entry)); 3295e22bee78STejun Heo } while (gcwq->nr_workers && rc >= 0); 3296e22bee78STejun Heo 3297e22bee78STejun Heo /* 3298e22bee78STejun Heo * At this point, either draining has completed and no worker 3299e22bee78STejun Heo * is left, or cpu down has been canceled or the cpu is being 3300e22bee78STejun Heo * brought back up. There shouldn't be any idle one left. 3301e22bee78STejun Heo * Tell the remaining busy ones to rebind once it finishes the 3302e22bee78STejun Heo * currently scheduled works by scheduling the rebind_work. 3303e22bee78STejun Heo */ 3304e22bee78STejun Heo WARN_ON(!list_empty(&gcwq->idle_list)); 3305e22bee78STejun Heo 3306e22bee78STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 3307e22bee78STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 3308e22bee78STejun Heo 3309e22bee78STejun Heo /* 3310e22bee78STejun Heo * Rebind_work may race with future cpu hotplug 3311e22bee78STejun Heo * operations. Use a separate flag to mark that 3312e22bee78STejun Heo * rebinding is scheduled. 3313e22bee78STejun Heo */ 3314cb444766STejun Heo worker->flags |= WORKER_REBIND; 3315cb444766STejun Heo worker->flags &= ~WORKER_ROGUE; 3316e22bee78STejun Heo 3317e22bee78STejun Heo /* queue rebind_work, wq doesn't matter, use the default one */ 3318e22bee78STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 3319e22bee78STejun Heo work_data_bits(rebind_work))) 3320e22bee78STejun Heo continue; 3321e22bee78STejun Heo 3322e22bee78STejun Heo debug_work_activate(rebind_work); 3323d320c038STejun Heo insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, 3324e22bee78STejun Heo worker->scheduled.next, 3325e22bee78STejun Heo work_color_to_flags(WORK_NO_COLOR)); 3326e22bee78STejun Heo } 3327e22bee78STejun Heo 3328e22bee78STejun Heo /* relinquish manager role */ 3329e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 3330e22bee78STejun Heo 3331db7bccf4STejun Heo /* notify completion */ 3332db7bccf4STejun Heo gcwq->trustee = NULL; 3333db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3334db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3335db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3336db7bccf4STejun Heo return 0; 3337db7bccf4STejun Heo } 3338db7bccf4STejun Heo 3339db7bccf4STejun Heo /** 3340db7bccf4STejun Heo * wait_trustee_state - wait for trustee to enter the specified state 3341db7bccf4STejun Heo * @gcwq: gcwq the trustee of interest belongs to 3342db7bccf4STejun Heo * @state: target state to wait for 3343db7bccf4STejun Heo * 3344db7bccf4STejun Heo * Wait for the trustee to reach @state. DONE is already matched. 3345db7bccf4STejun Heo * 3346db7bccf4STejun Heo * CONTEXT: 3347db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3348db7bccf4STejun Heo * multiple times. To be used by cpu_callback. 3349db7bccf4STejun Heo */ 3350db7bccf4STejun Heo static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) 335106bd6ebfSNamhyung Kim __releases(&gcwq->lock) 335206bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 3353db7bccf4STejun Heo { 3354db7bccf4STejun Heo if (!(gcwq->trustee_state == state || 3355db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE)) { 3356db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3357db7bccf4STejun Heo __wait_event(gcwq->trustee_wait, 3358db7bccf4STejun Heo gcwq->trustee_state == state || 3359db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE); 3360db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3361db7bccf4STejun Heo } 3362db7bccf4STejun Heo } 3363db7bccf4STejun Heo 33649c7b216dSChandra Seetharaman static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 33651da177e4SLinus Torvalds unsigned long action, 33661da177e4SLinus Torvalds void *hcpu) 33671da177e4SLinus Torvalds { 33683af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 3369db7bccf4STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3370db7bccf4STejun Heo struct task_struct *new_trustee = NULL; 3371e22bee78STejun Heo struct worker *uninitialized_var(new_worker); 3372db7bccf4STejun Heo unsigned long flags; 33731da177e4SLinus Torvalds 33748bb78442SRafael J. Wysocki action &= ~CPU_TASKS_FROZEN; 33758bb78442SRafael J. Wysocki 33761da177e4SLinus Torvalds switch (action) { 3377db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3378db7bccf4STejun Heo new_trustee = kthread_create(trustee_thread, gcwq, 3379db7bccf4STejun Heo "workqueue_trustee/%d\n", cpu); 3380db7bccf4STejun Heo if (IS_ERR(new_trustee)) 3381db7bccf4STejun Heo return notifier_from_errno(PTR_ERR(new_trustee)); 3382db7bccf4STejun Heo kthread_bind(new_trustee, cpu); 3383e22bee78STejun Heo /* fall through */ 33843af24433SOleg Nesterov case CPU_UP_PREPARE: 3385e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3386e22bee78STejun Heo new_worker = create_worker(gcwq, false); 3387e22bee78STejun Heo if (!new_worker) { 3388e22bee78STejun Heo if (new_trustee) 3389e22bee78STejun Heo kthread_stop(new_trustee); 3390e22bee78STejun Heo return NOTIFY_BAD; 33913af24433SOleg Nesterov } 3392db7bccf4STejun Heo } 33931537663fSTejun Heo 3394db7bccf4STejun Heo /* some are called w/ irq disabled, don't disturb irq status */ 3395db7bccf4STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 33963af24433SOleg Nesterov 33973af24433SOleg Nesterov switch (action) { 3398db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3399db7bccf4STejun Heo /* initialize trustee and tell it to acquire the gcwq */ 3400db7bccf4STejun Heo BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); 3401db7bccf4STejun Heo gcwq->trustee = new_trustee; 3402db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_START; 3403db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3404db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); 3405e22bee78STejun Heo /* fall through */ 34063af24433SOleg Nesterov case CPU_UP_PREPARE: 3407e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3408e22bee78STejun Heo gcwq->first_idle = new_worker; 34091da177e4SLinus Torvalds break; 34101da177e4SLinus Torvalds 3411e22bee78STejun Heo case CPU_DYING: 3412e22bee78STejun Heo /* 3413e22bee78STejun Heo * Before this, the trustee and all workers except for 3414e22bee78STejun Heo * the ones which are still executing works from 3415e22bee78STejun Heo * before the last CPU down must be on the cpu. After 3416e22bee78STejun Heo * this, they'll all be diasporas. 3417e22bee78STejun Heo */ 3418e22bee78STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 3419db7bccf4STejun Heo break; 3420db7bccf4STejun Heo 34213da1c84cSOleg Nesterov case CPU_POST_DEAD: 3422db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_BUTCHER; 3423e22bee78STejun Heo /* fall through */ 3424e22bee78STejun Heo case CPU_UP_CANCELED: 3425e22bee78STejun Heo destroy_worker(gcwq->first_idle); 3426e22bee78STejun Heo gcwq->first_idle = NULL; 3427db7bccf4STejun Heo break; 3428db7bccf4STejun Heo 3429db7bccf4STejun Heo case CPU_DOWN_FAILED: 34301da177e4SLinus Torvalds case CPU_ONLINE: 3431e22bee78STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3432db7bccf4STejun Heo if (gcwq->trustee_state != TRUSTEE_DONE) { 3433db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_RELEASE; 3434db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3435db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_DONE); 3436db7bccf4STejun Heo } 34371da177e4SLinus Torvalds 3438e22bee78STejun Heo /* 3439e22bee78STejun Heo * Trustee is done and there might be no worker left. 3440e22bee78STejun Heo * Put the first_idle in and request a real manager to 3441e22bee78STejun Heo * take a look. 3442e22bee78STejun Heo */ 3443e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3444e22bee78STejun Heo kthread_bind(gcwq->first_idle->task, cpu); 3445e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3446e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 3447e22bee78STejun Heo start_worker(gcwq->first_idle); 3448e22bee78STejun Heo gcwq->first_idle = NULL; 34491da177e4SLinus Torvalds break; 34501da177e4SLinus Torvalds } 34511da177e4SLinus Torvalds 3452db7bccf4STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 345300dfcaf7SOleg Nesterov 34541537663fSTejun Heo return notifier_from_errno(0); 34551da177e4SLinus Torvalds } 34561da177e4SLinus Torvalds 34572d3854a3SRusty Russell #ifdef CONFIG_SMP 34588ccad40dSRusty Russell 34592d3854a3SRusty Russell struct work_for_cpu { 34606b44003eSAndrew Morton struct completion completion; 34612d3854a3SRusty Russell long (*fn)(void *); 34622d3854a3SRusty Russell void *arg; 34632d3854a3SRusty Russell long ret; 34642d3854a3SRusty Russell }; 34652d3854a3SRusty Russell 34666b44003eSAndrew Morton static int do_work_for_cpu(void *_wfc) 34672d3854a3SRusty Russell { 34686b44003eSAndrew Morton struct work_for_cpu *wfc = _wfc; 34692d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 34706b44003eSAndrew Morton complete(&wfc->completion); 34716b44003eSAndrew Morton return 0; 34722d3854a3SRusty Russell } 34732d3854a3SRusty Russell 34742d3854a3SRusty Russell /** 34752d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 34762d3854a3SRusty Russell * @cpu: the cpu to run on 34772d3854a3SRusty Russell * @fn: the function to run 34782d3854a3SRusty Russell * @arg: the function arg 34792d3854a3SRusty Russell * 348031ad9081SRusty Russell * This will return the value @fn returns. 348131ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 34826b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 34832d3854a3SRusty Russell */ 34842d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 34852d3854a3SRusty Russell { 34866b44003eSAndrew Morton struct task_struct *sub_thread; 34876b44003eSAndrew Morton struct work_for_cpu wfc = { 34886b44003eSAndrew Morton .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), 34896b44003eSAndrew Morton .fn = fn, 34906b44003eSAndrew Morton .arg = arg, 34916b44003eSAndrew Morton }; 34922d3854a3SRusty Russell 34936b44003eSAndrew Morton sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); 34946b44003eSAndrew Morton if (IS_ERR(sub_thread)) 34956b44003eSAndrew Morton return PTR_ERR(sub_thread); 34966b44003eSAndrew Morton kthread_bind(sub_thread, cpu); 34976b44003eSAndrew Morton wake_up_process(sub_thread); 34986b44003eSAndrew Morton wait_for_completion(&wfc.completion); 34992d3854a3SRusty Russell return wfc.ret; 35002d3854a3SRusty Russell } 35012d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 35022d3854a3SRusty Russell #endif /* CONFIG_SMP */ 35032d3854a3SRusty Russell 3504a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3505e7577c50SRusty Russell 3506a0a1a5fdSTejun Heo /** 3507a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3508a0a1a5fdSTejun Heo * 3509a0a1a5fdSTejun Heo * Start freezing workqueues. After this function returns, all 3510a0a1a5fdSTejun Heo * freezeable workqueues will queue new works to their frozen_works 35117e11629dSTejun Heo * list instead of gcwq->worklist. 3512a0a1a5fdSTejun Heo * 3513a0a1a5fdSTejun Heo * CONTEXT: 35148b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3515a0a1a5fdSTejun Heo */ 3516a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3517a0a1a5fdSTejun Heo { 3518a0a1a5fdSTejun Heo unsigned int cpu; 3519a0a1a5fdSTejun Heo 3520a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3521a0a1a5fdSTejun Heo 3522a0a1a5fdSTejun Heo BUG_ON(workqueue_freezing); 3523a0a1a5fdSTejun Heo workqueue_freezing = true; 3524a0a1a5fdSTejun Heo 3525f3421797STejun Heo for_each_gcwq_cpu(cpu) { 35268b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3527bdbc5dd7STejun Heo struct workqueue_struct *wq; 35288b03ae3cSTejun Heo 35298b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 35308b03ae3cSTejun Heo 3531db7bccf4STejun Heo BUG_ON(gcwq->flags & GCWQ_FREEZING); 3532db7bccf4STejun Heo gcwq->flags |= GCWQ_FREEZING; 3533db7bccf4STejun Heo 3534a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3535a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3536a0a1a5fdSTejun Heo 3537f3421797STejun Heo if (cwq && wq->flags & WQ_FREEZEABLE) 3538a0a1a5fdSTejun Heo cwq->max_active = 0; 35391da177e4SLinus Torvalds } 35408b03ae3cSTejun Heo 35418b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3542a0a1a5fdSTejun Heo } 3543a0a1a5fdSTejun Heo 3544a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3545a0a1a5fdSTejun Heo } 3546a0a1a5fdSTejun Heo 3547a0a1a5fdSTejun Heo /** 3548a0a1a5fdSTejun Heo * freeze_workqueues_busy - are freezeable workqueues still busy? 3549a0a1a5fdSTejun Heo * 3550a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3551a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3552a0a1a5fdSTejun Heo * 3553a0a1a5fdSTejun Heo * CONTEXT: 3554a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3555a0a1a5fdSTejun Heo * 3556a0a1a5fdSTejun Heo * RETURNS: 3557a0a1a5fdSTejun Heo * %true if some freezeable workqueues are still busy. %false if 3558a0a1a5fdSTejun Heo * freezing is complete. 3559a0a1a5fdSTejun Heo */ 3560a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3561a0a1a5fdSTejun Heo { 3562a0a1a5fdSTejun Heo unsigned int cpu; 3563a0a1a5fdSTejun Heo bool busy = false; 3564a0a1a5fdSTejun Heo 3565a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3566a0a1a5fdSTejun Heo 3567a0a1a5fdSTejun Heo BUG_ON(!workqueue_freezing); 3568a0a1a5fdSTejun Heo 3569f3421797STejun Heo for_each_gcwq_cpu(cpu) { 3570bdbc5dd7STejun Heo struct workqueue_struct *wq; 3571a0a1a5fdSTejun Heo /* 3572a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3573a0a1a5fdSTejun Heo * to peek without lock. 3574a0a1a5fdSTejun Heo */ 3575a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3576a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3577a0a1a5fdSTejun Heo 3578f3421797STejun Heo if (!cwq || !(wq->flags & WQ_FREEZEABLE)) 3579a0a1a5fdSTejun Heo continue; 3580a0a1a5fdSTejun Heo 3581a0a1a5fdSTejun Heo BUG_ON(cwq->nr_active < 0); 3582a0a1a5fdSTejun Heo if (cwq->nr_active) { 3583a0a1a5fdSTejun Heo busy = true; 3584a0a1a5fdSTejun Heo goto out_unlock; 3585a0a1a5fdSTejun Heo } 3586a0a1a5fdSTejun Heo } 3587a0a1a5fdSTejun Heo } 3588a0a1a5fdSTejun Heo out_unlock: 3589a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3590a0a1a5fdSTejun Heo return busy; 3591a0a1a5fdSTejun Heo } 3592a0a1a5fdSTejun Heo 3593a0a1a5fdSTejun Heo /** 3594a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3595a0a1a5fdSTejun Heo * 3596a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 35977e11629dSTejun Heo * frozen works are transferred to their respective gcwq worklists. 3598a0a1a5fdSTejun Heo * 3599a0a1a5fdSTejun Heo * CONTEXT: 36008b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3601a0a1a5fdSTejun Heo */ 3602a0a1a5fdSTejun Heo void thaw_workqueues(void) 3603a0a1a5fdSTejun Heo { 3604a0a1a5fdSTejun Heo unsigned int cpu; 3605a0a1a5fdSTejun Heo 3606a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3607a0a1a5fdSTejun Heo 3608a0a1a5fdSTejun Heo if (!workqueue_freezing) 3609a0a1a5fdSTejun Heo goto out_unlock; 3610a0a1a5fdSTejun Heo 3611f3421797STejun Heo for_each_gcwq_cpu(cpu) { 36128b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3613bdbc5dd7STejun Heo struct workqueue_struct *wq; 36148b03ae3cSTejun Heo 36158b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 36168b03ae3cSTejun Heo 3617db7bccf4STejun Heo BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); 3618db7bccf4STejun Heo gcwq->flags &= ~GCWQ_FREEZING; 3619db7bccf4STejun Heo 3620a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3621a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3622a0a1a5fdSTejun Heo 3623f3421797STejun Heo if (!cwq || !(wq->flags & WQ_FREEZEABLE)) 3624a0a1a5fdSTejun Heo continue; 3625a0a1a5fdSTejun Heo 3626a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 3627a0a1a5fdSTejun Heo cwq->max_active = wq->saved_max_active; 3628a0a1a5fdSTejun Heo 3629a0a1a5fdSTejun Heo while (!list_empty(&cwq->delayed_works) && 3630a0a1a5fdSTejun Heo cwq->nr_active < cwq->max_active) 3631a0a1a5fdSTejun Heo cwq_activate_first_delayed(cwq); 3632a0a1a5fdSTejun Heo } 36338b03ae3cSTejun Heo 3634e22bee78STejun Heo wake_up_worker(gcwq); 3635e22bee78STejun Heo 36368b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3637a0a1a5fdSTejun Heo } 3638a0a1a5fdSTejun Heo 3639a0a1a5fdSTejun Heo workqueue_freezing = false; 3640a0a1a5fdSTejun Heo out_unlock: 3641a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3642a0a1a5fdSTejun Heo } 3643a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3644a0a1a5fdSTejun Heo 36456ee0578bSSuresh Siddha static int __init init_workqueues(void) 36461da177e4SLinus Torvalds { 3647c34056a3STejun Heo unsigned int cpu; 3648c8e55f36STejun Heo int i; 3649c34056a3STejun Heo 3650f6500947STejun Heo cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); 36518b03ae3cSTejun Heo 36528b03ae3cSTejun Heo /* initialize gcwqs */ 3653f3421797STejun Heo for_each_gcwq_cpu(cpu) { 36548b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 36558b03ae3cSTejun Heo 36568b03ae3cSTejun Heo spin_lock_init(&gcwq->lock); 36577e11629dSTejun Heo INIT_LIST_HEAD(&gcwq->worklist); 36588b03ae3cSTejun Heo gcwq->cpu = cpu; 3659f3421797STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 36608b03ae3cSTejun Heo 3661c8e55f36STejun Heo INIT_LIST_HEAD(&gcwq->idle_list); 3662c8e55f36STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) 3663c8e55f36STejun Heo INIT_HLIST_HEAD(&gcwq->busy_hash[i]); 3664c8e55f36STejun Heo 3665e22bee78STejun Heo init_timer_deferrable(&gcwq->idle_timer); 3666e22bee78STejun Heo gcwq->idle_timer.function = idle_worker_timeout; 3667e22bee78STejun Heo gcwq->idle_timer.data = (unsigned long)gcwq; 3668e22bee78STejun Heo 3669e22bee78STejun Heo setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, 3670e22bee78STejun Heo (unsigned long)gcwq); 3671e22bee78STejun Heo 36728b03ae3cSTejun Heo ida_init(&gcwq->worker_ida); 3673db7bccf4STejun Heo 3674db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3675db7bccf4STejun Heo init_waitqueue_head(&gcwq->trustee_wait); 36768b03ae3cSTejun Heo } 36778b03ae3cSTejun Heo 3678e22bee78STejun Heo /* create the initial worker */ 3679f3421797STejun Heo for_each_online_gcwq_cpu(cpu) { 3680e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3681e22bee78STejun Heo struct worker *worker; 3682e22bee78STejun Heo 3683477a3c33STejun Heo if (cpu != WORK_CPU_UNBOUND) 3684477a3c33STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3685e22bee78STejun Heo worker = create_worker(gcwq, true); 3686e22bee78STejun Heo BUG_ON(!worker); 3687e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3688e22bee78STejun Heo start_worker(worker); 3689e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3690e22bee78STejun Heo } 3691e22bee78STejun Heo 3692d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 3693d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3694d320c038STejun Heo system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); 3695f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3696f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 3697d320c038STejun Heo BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq); 36986ee0578bSSuresh Siddha return 0; 36991da177e4SLinus Torvalds } 37006ee0578bSSuresh Siddha early_initcall(init_workqueues); 3701