11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/kernel/workqueue.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Generic mechanism for defining kernel helper threads for running 51da177e4SLinus Torvalds * arbitrary tasks in process context. 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Started by Ingo Molnar, Copyright (C) 2002 81da177e4SLinus Torvalds * 91da177e4SLinus Torvalds * Derived from the taskqueue/keventd code by: 101da177e4SLinus Torvalds * 111da177e4SLinus Torvalds * David Woodhouse <dwmw2@infradead.org> 12e1f8e874SFrancois Cami * Andrew Morton 131da177e4SLinus Torvalds * Kai Petzke <wpp@marie.physik.tu-berlin.de> 141da177e4SLinus Torvalds * Theodore Ts'o <tytso@mit.edu> 1589ada679SChristoph Lameter * 16cde53535SChristoph Lameter * Made to use alloc_percpu by Christoph Lameter. 171da177e4SLinus Torvalds */ 181da177e4SLinus Torvalds 191da177e4SLinus Torvalds #include <linux/module.h> 201da177e4SLinus Torvalds #include <linux/kernel.h> 211da177e4SLinus Torvalds #include <linux/sched.h> 221da177e4SLinus Torvalds #include <linux/init.h> 231da177e4SLinus Torvalds #include <linux/signal.h> 241da177e4SLinus Torvalds #include <linux/completion.h> 251da177e4SLinus Torvalds #include <linux/workqueue.h> 261da177e4SLinus Torvalds #include <linux/slab.h> 271da177e4SLinus Torvalds #include <linux/cpu.h> 281da177e4SLinus Torvalds #include <linux/notifier.h> 291da177e4SLinus Torvalds #include <linux/kthread.h> 301fa44ecaSJames Bottomley #include <linux/hardirq.h> 3146934023SChristoph Lameter #include <linux/mempolicy.h> 32341a5958SRafael J. Wysocki #include <linux/freezer.h> 33d5abe669SPeter Zijlstra #include <linux/kallsyms.h> 34d5abe669SPeter Zijlstra #include <linux/debug_locks.h> 354e6045f1SJohannes Berg #include <linux/lockdep.h> 36c34056a3STejun Heo #include <linux/idr.h> 37e22bee78STejun Heo 38e22bee78STejun Heo #include "workqueue_sched.h" 391da177e4SLinus Torvalds 40c8e55f36STejun Heo enum { 41db7bccf4STejun Heo /* global_cwq flags */ 42e22bee78STejun Heo GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ 43e22bee78STejun Heo GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */ 44e22bee78STejun Heo GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 45db7bccf4STejun Heo GCWQ_FREEZING = 1 << 3, /* freeze in progress */ 46649027d7STejun Heo GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */ 47db7bccf4STejun Heo 48c8e55f36STejun Heo /* worker flags */ 49c8e55f36STejun Heo WORKER_STARTED = 1 << 0, /* started */ 50c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 51c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 52e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 53db7bccf4STejun Heo WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ 54e22bee78STejun Heo WORKER_REBIND = 1 << 5, /* mom is home, come back */ 55fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 56e22bee78STejun Heo 57fb0e7bebSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | 58fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE, 59db7bccf4STejun Heo 60db7bccf4STejun Heo /* gcwq->trustee_state */ 61db7bccf4STejun Heo TRUSTEE_START = 0, /* start */ 62db7bccf4STejun Heo TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ 63db7bccf4STejun Heo TRUSTEE_BUTCHER = 2, /* butcher workers */ 64db7bccf4STejun Heo TRUSTEE_RELEASE = 3, /* release workers */ 65db7bccf4STejun Heo TRUSTEE_DONE = 4, /* trustee is done */ 66c8e55f36STejun Heo 67c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 68c8e55f36STejun Heo BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, 69c8e55f36STejun Heo BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, 70db7bccf4STejun Heo 71e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 72e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 73e22bee78STejun Heo 74e22bee78STejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */ 75e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 76e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 77db7bccf4STejun Heo TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ 78e22bee78STejun Heo 79e22bee78STejun Heo /* 80e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 81e22bee78STejun Heo * all cpus. Give -20. 82e22bee78STejun Heo */ 83e22bee78STejun Heo RESCUER_NICE_LEVEL = -20, 84c8e55f36STejun Heo }; 85c8e55f36STejun Heo 861da177e4SLinus Torvalds /* 874690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 884690c4abSTejun Heo * 894690c4abSTejun Heo * I: Set during initialization and read-only afterwards. 904690c4abSTejun Heo * 91e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 92e22bee78STejun Heo * only be modified and accessed from the local cpu. 93e22bee78STejun Heo * 948b03ae3cSTejun Heo * L: gcwq->lock protected. Access with gcwq->lock held. 954690c4abSTejun Heo * 96e22bee78STejun Heo * X: During normal operation, modification requires gcwq->lock and 97e22bee78STejun Heo * should be done only from local cpu. Either disabling preemption 98e22bee78STejun Heo * on local cpu or grabbing gcwq->lock is enough for read access. 99e22bee78STejun Heo * While trustee is in charge, it's identical to L. 100e22bee78STejun Heo * 10173f53c4aSTejun Heo * F: wq->flush_mutex protected. 10273f53c4aSTejun Heo * 1034690c4abSTejun Heo * W: workqueue_lock protected. 1044690c4abSTejun Heo */ 1054690c4abSTejun Heo 1068b03ae3cSTejun Heo struct global_cwq; 107c34056a3STejun Heo 108e22bee78STejun Heo /* 109e22bee78STejun Heo * The poor guys doing the actual heavy lifting. All on-duty workers 110e22bee78STejun Heo * are either serving the manager role, on idle list or on busy hash. 111e22bee78STejun Heo */ 112c34056a3STejun Heo struct worker { 113c8e55f36STejun Heo /* on idle list while idle, on busy hash table while busy */ 114c8e55f36STejun Heo union { 115c8e55f36STejun Heo struct list_head entry; /* L: while idle */ 116c8e55f36STejun Heo struct hlist_node hentry; /* L: while busy */ 117c8e55f36STejun Heo }; 118c8e55f36STejun Heo 119c34056a3STejun Heo struct work_struct *current_work; /* L: work being processed */ 1208cca0eeaSTejun Heo struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ 121affee4b2STejun Heo struct list_head scheduled; /* L: scheduled works */ 122c34056a3STejun Heo struct task_struct *task; /* I: worker task */ 1238b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 124e22bee78STejun Heo /* 64 bytes boundary on 64bit, 32 on 32bit */ 125e22bee78STejun Heo unsigned long last_active; /* L: last active timestamp */ 126e22bee78STejun Heo unsigned int flags; /* X: flags */ 127c34056a3STejun Heo int id; /* I: worker id */ 128e22bee78STejun Heo struct work_struct rebind_work; /* L: rebind worker to cpu */ 129c34056a3STejun Heo }; 130c34056a3STejun Heo 1314690c4abSTejun Heo /* 132e22bee78STejun Heo * Global per-cpu workqueue. There's one and only one for each cpu 133e22bee78STejun Heo * and all works are queued and processed here regardless of their 134e22bee78STejun Heo * target workqueues. 1358b03ae3cSTejun Heo */ 1368b03ae3cSTejun Heo struct global_cwq { 1378b03ae3cSTejun Heo spinlock_t lock; /* the gcwq lock */ 1387e11629dSTejun Heo struct list_head worklist; /* L: list of pending works */ 1398b03ae3cSTejun Heo unsigned int cpu; /* I: the associated cpu */ 140db7bccf4STejun Heo unsigned int flags; /* L: GCWQ_* flags */ 141c8e55f36STejun Heo 142c8e55f36STejun Heo int nr_workers; /* L: total number of workers */ 143c8e55f36STejun Heo int nr_idle; /* L: currently idle ones */ 144c8e55f36STejun Heo 145c8e55f36STejun Heo /* workers are chained either in the idle_list or busy_hash */ 146e22bee78STejun Heo struct list_head idle_list; /* X: list of idle workers */ 147c8e55f36STejun Heo struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; 148c8e55f36STejun Heo /* L: hash of busy workers */ 149c8e55f36STejun Heo 150e22bee78STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 151e22bee78STejun Heo struct timer_list mayday_timer; /* L: SOS timer for dworkers */ 152e22bee78STejun Heo 1538b03ae3cSTejun Heo struct ida worker_ida; /* L: for worker IDs */ 154db7bccf4STejun Heo 155db7bccf4STejun Heo struct task_struct *trustee; /* L: for gcwq shutdown */ 156db7bccf4STejun Heo unsigned int trustee_state; /* L: trustee state */ 157db7bccf4STejun Heo wait_queue_head_t trustee_wait; /* trustee wait */ 158e22bee78STejun Heo struct worker *first_idle; /* L: first idle worker */ 1598b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1608b03ae3cSTejun Heo 1618b03ae3cSTejun Heo /* 162502ca9d8STejun Heo * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of 1630f900049STejun Heo * work_struct->data are used for flags and thus cwqs need to be 1640f900049STejun Heo * aligned at two's power of the number of flag bits. 1651da177e4SLinus Torvalds */ 1661da177e4SLinus Torvalds struct cpu_workqueue_struct { 1678b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 1684690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 16973f53c4aSTejun Heo int work_color; /* L: current color */ 17073f53c4aSTejun Heo int flush_color; /* L: flushing color */ 17173f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 17273f53c4aSTejun Heo /* L: nr of in_flight works */ 1731e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 174a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 1751e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 1760f900049STejun Heo }; 1771da177e4SLinus Torvalds 1781da177e4SLinus Torvalds /* 17973f53c4aSTejun Heo * Structure used to wait for workqueue flush. 18073f53c4aSTejun Heo */ 18173f53c4aSTejun Heo struct wq_flusher { 18273f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 18373f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 18473f53c4aSTejun Heo struct completion done; /* flush completion */ 18573f53c4aSTejun Heo }; 18673f53c4aSTejun Heo 18773f53c4aSTejun Heo /* 1881da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 1891da177e4SLinus Torvalds * per-CPU workqueues: 1901da177e4SLinus Torvalds */ 1911da177e4SLinus Torvalds struct workqueue_struct { 19297e37d7bSTejun Heo unsigned int flags; /* I: WQ_* flags */ 1934690c4abSTejun Heo struct cpu_workqueue_struct *cpu_wq; /* I: cwq's */ 1944690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 19573f53c4aSTejun Heo 19673f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 19773f53c4aSTejun Heo int work_color; /* F: current work color */ 19873f53c4aSTejun Heo int flush_color; /* F: current flush color */ 19973f53c4aSTejun Heo atomic_t nr_cwqs_to_flush; /* flush in progress */ 20073f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 20173f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 20273f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 20373f53c4aSTejun Heo 204502ca9d8STejun Heo unsigned long single_cpu; /* cpu for single cpu wq */ 205502ca9d8STejun Heo 206e22bee78STejun Heo cpumask_var_t mayday_mask; /* cpus requesting rescue */ 207e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 208e22bee78STejun Heo 209dcd989cbSTejun Heo int saved_max_active; /* W: saved cwq max_active */ 2104690c4abSTejun Heo const char *name; /* I: workqueue name */ 2114e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2124e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2134e6045f1SJohannes Berg #endif 2141da177e4SLinus Torvalds }; 2151da177e4SLinus Torvalds 216d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 217d320c038STejun Heo struct workqueue_struct *system_long_wq __read_mostly; 218d320c038STejun Heo struct workqueue_struct *system_nrt_wq __read_mostly; 219d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 220d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 221d320c038STejun Heo EXPORT_SYMBOL_GPL(system_nrt_wq); 222d320c038STejun Heo 223db7bccf4STejun Heo #define for_each_busy_worker(worker, i, pos, gcwq) \ 224db7bccf4STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ 225db7bccf4STejun Heo hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) 226db7bccf4STejun Heo 227dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 228dc186ad7SThomas Gleixner 229dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 230dc186ad7SThomas Gleixner 231dc186ad7SThomas Gleixner /* 232dc186ad7SThomas Gleixner * fixup_init is called when: 233dc186ad7SThomas Gleixner * - an active object is initialized 234dc186ad7SThomas Gleixner */ 235dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 236dc186ad7SThomas Gleixner { 237dc186ad7SThomas Gleixner struct work_struct *work = addr; 238dc186ad7SThomas Gleixner 239dc186ad7SThomas Gleixner switch (state) { 240dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 241dc186ad7SThomas Gleixner cancel_work_sync(work); 242dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 243dc186ad7SThomas Gleixner return 1; 244dc186ad7SThomas Gleixner default: 245dc186ad7SThomas Gleixner return 0; 246dc186ad7SThomas Gleixner } 247dc186ad7SThomas Gleixner } 248dc186ad7SThomas Gleixner 249dc186ad7SThomas Gleixner /* 250dc186ad7SThomas Gleixner * fixup_activate is called when: 251dc186ad7SThomas Gleixner * - an active object is activated 252dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 253dc186ad7SThomas Gleixner */ 254dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 255dc186ad7SThomas Gleixner { 256dc186ad7SThomas Gleixner struct work_struct *work = addr; 257dc186ad7SThomas Gleixner 258dc186ad7SThomas Gleixner switch (state) { 259dc186ad7SThomas Gleixner 260dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 261dc186ad7SThomas Gleixner /* 262dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 263dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 264dc186ad7SThomas Gleixner * is tracked in the object tracker. 265dc186ad7SThomas Gleixner */ 26622df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 267dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 268dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 269dc186ad7SThomas Gleixner return 0; 270dc186ad7SThomas Gleixner } 271dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 272dc186ad7SThomas Gleixner return 0; 273dc186ad7SThomas Gleixner 274dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 275dc186ad7SThomas Gleixner WARN_ON(1); 276dc186ad7SThomas Gleixner 277dc186ad7SThomas Gleixner default: 278dc186ad7SThomas Gleixner return 0; 279dc186ad7SThomas Gleixner } 280dc186ad7SThomas Gleixner } 281dc186ad7SThomas Gleixner 282dc186ad7SThomas Gleixner /* 283dc186ad7SThomas Gleixner * fixup_free is called when: 284dc186ad7SThomas Gleixner * - an active object is freed 285dc186ad7SThomas Gleixner */ 286dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 287dc186ad7SThomas Gleixner { 288dc186ad7SThomas Gleixner struct work_struct *work = addr; 289dc186ad7SThomas Gleixner 290dc186ad7SThomas Gleixner switch (state) { 291dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 292dc186ad7SThomas Gleixner cancel_work_sync(work); 293dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 294dc186ad7SThomas Gleixner return 1; 295dc186ad7SThomas Gleixner default: 296dc186ad7SThomas Gleixner return 0; 297dc186ad7SThomas Gleixner } 298dc186ad7SThomas Gleixner } 299dc186ad7SThomas Gleixner 300dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 301dc186ad7SThomas Gleixner .name = "work_struct", 302dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 303dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 304dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 305dc186ad7SThomas Gleixner }; 306dc186ad7SThomas Gleixner 307dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 308dc186ad7SThomas Gleixner { 309dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 310dc186ad7SThomas Gleixner } 311dc186ad7SThomas Gleixner 312dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 313dc186ad7SThomas Gleixner { 314dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 315dc186ad7SThomas Gleixner } 316dc186ad7SThomas Gleixner 317dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 318dc186ad7SThomas Gleixner { 319dc186ad7SThomas Gleixner if (onstack) 320dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 321dc186ad7SThomas Gleixner else 322dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 323dc186ad7SThomas Gleixner } 324dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 325dc186ad7SThomas Gleixner 326dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 327dc186ad7SThomas Gleixner { 328dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 329dc186ad7SThomas Gleixner } 330dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 331dc186ad7SThomas Gleixner 332dc186ad7SThomas Gleixner #else 333dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 334dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 335dc186ad7SThomas Gleixner #endif 336dc186ad7SThomas Gleixner 33795402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 33895402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 3391da177e4SLinus Torvalds static LIST_HEAD(workqueues); 340a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 341c34056a3STejun Heo 342e22bee78STejun Heo /* 343e22bee78STejun Heo * The almighty global cpu workqueues. nr_running is the only field 344e22bee78STejun Heo * which is expected to be used frequently by other cpus via 345e22bee78STejun Heo * try_to_wake_up(). Put it in a separate cacheline. 346e22bee78STejun Heo */ 3478b03ae3cSTejun Heo static DEFINE_PER_CPU(struct global_cwq, global_cwq); 348e22bee78STejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); 3498b03ae3cSTejun Heo 350c34056a3STejun Heo static int worker_thread(void *__worker); 3511da177e4SLinus Torvalds 3528b03ae3cSTejun Heo static struct global_cwq *get_gcwq(unsigned int cpu) 3538b03ae3cSTejun Heo { 3548b03ae3cSTejun Heo return &per_cpu(global_cwq, cpu); 3558b03ae3cSTejun Heo } 3568b03ae3cSTejun Heo 357e22bee78STejun Heo static atomic_t *get_gcwq_nr_running(unsigned int cpu) 358e22bee78STejun Heo { 359e22bee78STejun Heo return &per_cpu(gcwq_nr_running, cpu); 360e22bee78STejun Heo } 361e22bee78STejun Heo 3624690c4abSTejun Heo static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, 3634690c4abSTejun Heo struct workqueue_struct *wq) 364a848e3b6SOleg Nesterov { 365a848e3b6SOleg Nesterov return per_cpu_ptr(wq->cpu_wq, cpu); 366a848e3b6SOleg Nesterov } 367a848e3b6SOleg Nesterov 36873f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 36973f53c4aSTejun Heo { 37073f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 37173f53c4aSTejun Heo } 37273f53c4aSTejun Heo 37373f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 37473f53c4aSTejun Heo { 37573f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 37673f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 37773f53c4aSTejun Heo } 37873f53c4aSTejun Heo 37973f53c4aSTejun Heo static int work_next_color(int color) 38073f53c4aSTejun Heo { 38173f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 38273f53c4aSTejun Heo } 38373f53c4aSTejun Heo 3844594bf15SDavid Howells /* 3857a22ad75STejun Heo * Work data points to the cwq while a work is on queue. Once 3867a22ad75STejun Heo * execution starts, it points to the cpu the work was last on. This 3877a22ad75STejun Heo * can be distinguished by comparing the data value against 3887a22ad75STejun Heo * PAGE_OFFSET. 3897a22ad75STejun Heo * 3907a22ad75STejun Heo * set_work_{cwq|cpu}() and clear_work_data() can be used to set the 3917a22ad75STejun Heo * cwq, cpu or clear work->data. These functions should only be 3927a22ad75STejun Heo * called while the work is owned - ie. while the PENDING bit is set. 3937a22ad75STejun Heo * 3947a22ad75STejun Heo * get_work_[g]cwq() can be used to obtain the gcwq or cwq 3957a22ad75STejun Heo * corresponding to a work. gcwq is available once the work has been 3967a22ad75STejun Heo * queued anywhere after initialization. cwq is available only from 3977a22ad75STejun Heo * queueing until execution starts. 3984594bf15SDavid Howells */ 3997a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 4007a22ad75STejun Heo unsigned long flags) 4017a22ad75STejun Heo { 4027a22ad75STejun Heo BUG_ON(!work_pending(work)); 4037a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 4047a22ad75STejun Heo } 4057a22ad75STejun Heo 4067a22ad75STejun Heo static void set_work_cwq(struct work_struct *work, 4074690c4abSTejun Heo struct cpu_workqueue_struct *cwq, 4084690c4abSTejun Heo unsigned long extra_flags) 409365970a1SDavid Howells { 4107a22ad75STejun Heo set_work_data(work, (unsigned long)cwq, 41122df02bbSTejun Heo WORK_STRUCT_PENDING | extra_flags); 412365970a1SDavid Howells } 413365970a1SDavid Howells 4147a22ad75STejun Heo static void set_work_cpu(struct work_struct *work, unsigned int cpu) 4154d707b9fSOleg Nesterov { 4167a22ad75STejun Heo set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); 4174d707b9fSOleg Nesterov } 4184d707b9fSOleg Nesterov 4197a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 420365970a1SDavid Howells { 4217a22ad75STejun Heo set_work_data(work, WORK_STRUCT_NO_CPU, 0); 4227a22ad75STejun Heo } 4237a22ad75STejun Heo 4247a22ad75STejun Heo static inline unsigned long get_work_data(struct work_struct *work) 4257a22ad75STejun Heo { 4267a22ad75STejun Heo return atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK; 4277a22ad75STejun Heo } 4287a22ad75STejun Heo 4297a22ad75STejun Heo static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) 4307a22ad75STejun Heo { 4317a22ad75STejun Heo unsigned long data = get_work_data(work); 4327a22ad75STejun Heo 4337a22ad75STejun Heo return data >= PAGE_OFFSET ? (void *)data : NULL; 4347a22ad75STejun Heo } 4357a22ad75STejun Heo 4367a22ad75STejun Heo static struct global_cwq *get_work_gcwq(struct work_struct *work) 4377a22ad75STejun Heo { 4387a22ad75STejun Heo unsigned long data = get_work_data(work); 4397a22ad75STejun Heo unsigned int cpu; 4407a22ad75STejun Heo 4417a22ad75STejun Heo if (data >= PAGE_OFFSET) 4427a22ad75STejun Heo return ((struct cpu_workqueue_struct *)data)->gcwq; 4437a22ad75STejun Heo 4447a22ad75STejun Heo cpu = data >> WORK_STRUCT_FLAG_BITS; 4457a22ad75STejun Heo if (cpu == NR_CPUS) 4467a22ad75STejun Heo return NULL; 4477a22ad75STejun Heo 448a1e453d2STejun Heo BUG_ON(cpu >= nr_cpu_ids); 4497a22ad75STejun Heo return get_gcwq(cpu); 450365970a1SDavid Howells } 451365970a1SDavid Howells 452e22bee78STejun Heo /* 453e22bee78STejun Heo * Policy functions. These define the policies on how the global 454e22bee78STejun Heo * worker pool is managed. Unless noted otherwise, these functions 455e22bee78STejun Heo * assume that they're being called with gcwq->lock held. 456e22bee78STejun Heo */ 457e22bee78STejun Heo 458649027d7STejun Heo static bool __need_more_worker(struct global_cwq *gcwq) 459649027d7STejun Heo { 460649027d7STejun Heo return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || 461649027d7STejun Heo gcwq->flags & GCWQ_HIGHPRI_PENDING; 462649027d7STejun Heo } 463649027d7STejun Heo 464e22bee78STejun Heo /* 465e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 466e22bee78STejun Heo * running workers. 467e22bee78STejun Heo */ 468e22bee78STejun Heo static bool need_more_worker(struct global_cwq *gcwq) 469e22bee78STejun Heo { 470649027d7STejun Heo return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); 471e22bee78STejun Heo } 472e22bee78STejun Heo 473e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 474e22bee78STejun Heo static bool may_start_working(struct global_cwq *gcwq) 475e22bee78STejun Heo { 476e22bee78STejun Heo return gcwq->nr_idle; 477e22bee78STejun Heo } 478e22bee78STejun Heo 479e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 480e22bee78STejun Heo static bool keep_working(struct global_cwq *gcwq) 481e22bee78STejun Heo { 482e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 483e22bee78STejun Heo 484e22bee78STejun Heo return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1; 485e22bee78STejun Heo } 486e22bee78STejun Heo 487e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 488e22bee78STejun Heo static bool need_to_create_worker(struct global_cwq *gcwq) 489e22bee78STejun Heo { 490e22bee78STejun Heo return need_more_worker(gcwq) && !may_start_working(gcwq); 491e22bee78STejun Heo } 492e22bee78STejun Heo 493e22bee78STejun Heo /* Do I need to be the manager? */ 494e22bee78STejun Heo static bool need_to_manage_workers(struct global_cwq *gcwq) 495e22bee78STejun Heo { 496e22bee78STejun Heo return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; 497e22bee78STejun Heo } 498e22bee78STejun Heo 499e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 500e22bee78STejun Heo static bool too_many_workers(struct global_cwq *gcwq) 501e22bee78STejun Heo { 502e22bee78STejun Heo bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; 503e22bee78STejun Heo int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ 504e22bee78STejun Heo int nr_busy = gcwq->nr_workers - nr_idle; 505e22bee78STejun Heo 506e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 507e22bee78STejun Heo } 508e22bee78STejun Heo 509e22bee78STejun Heo /* 510e22bee78STejun Heo * Wake up functions. 511e22bee78STejun Heo */ 512e22bee78STejun Heo 5137e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 5147e11629dSTejun Heo static struct worker *first_worker(struct global_cwq *gcwq) 5157e11629dSTejun Heo { 5167e11629dSTejun Heo if (unlikely(list_empty(&gcwq->idle_list))) 5177e11629dSTejun Heo return NULL; 5187e11629dSTejun Heo 5197e11629dSTejun Heo return list_first_entry(&gcwq->idle_list, struct worker, entry); 5207e11629dSTejun Heo } 5217e11629dSTejun Heo 5227e11629dSTejun Heo /** 5237e11629dSTejun Heo * wake_up_worker - wake up an idle worker 5247e11629dSTejun Heo * @gcwq: gcwq to wake worker for 5257e11629dSTejun Heo * 5267e11629dSTejun Heo * Wake up the first idle worker of @gcwq. 5277e11629dSTejun Heo * 5287e11629dSTejun Heo * CONTEXT: 5297e11629dSTejun Heo * spin_lock_irq(gcwq->lock). 5307e11629dSTejun Heo */ 5317e11629dSTejun Heo static void wake_up_worker(struct global_cwq *gcwq) 5327e11629dSTejun Heo { 5337e11629dSTejun Heo struct worker *worker = first_worker(gcwq); 5347e11629dSTejun Heo 5357e11629dSTejun Heo if (likely(worker)) 5367e11629dSTejun Heo wake_up_process(worker->task); 5377e11629dSTejun Heo } 5387e11629dSTejun Heo 5394690c4abSTejun Heo /** 540e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 541e22bee78STejun Heo * @task: task waking up 542e22bee78STejun Heo * @cpu: CPU @task is waking up to 543e22bee78STejun Heo * 544e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 545e22bee78STejun Heo * being awoken. 546e22bee78STejun Heo * 547e22bee78STejun Heo * CONTEXT: 548e22bee78STejun Heo * spin_lock_irq(rq->lock) 549e22bee78STejun Heo */ 550e22bee78STejun Heo void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) 551e22bee78STejun Heo { 552e22bee78STejun Heo struct worker *worker = kthread_data(task); 553e22bee78STejun Heo 554e22bee78STejun Heo if (likely(!(worker->flags & WORKER_NOT_RUNNING))) 555e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(cpu)); 556e22bee78STejun Heo } 557e22bee78STejun Heo 558e22bee78STejun Heo /** 559e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 560e22bee78STejun Heo * @task: task going to sleep 561e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 562e22bee78STejun Heo * 563e22bee78STejun Heo * This function is called during schedule() when a busy worker is 564e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 565e22bee78STejun Heo * returning pointer to its task. 566e22bee78STejun Heo * 567e22bee78STejun Heo * CONTEXT: 568e22bee78STejun Heo * spin_lock_irq(rq->lock) 569e22bee78STejun Heo * 570e22bee78STejun Heo * RETURNS: 571e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 572e22bee78STejun Heo */ 573e22bee78STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, 574e22bee78STejun Heo unsigned int cpu) 575e22bee78STejun Heo { 576e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 577e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 578e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(cpu); 579e22bee78STejun Heo 580e22bee78STejun Heo if (unlikely(worker->flags & WORKER_NOT_RUNNING)) 581e22bee78STejun Heo return NULL; 582e22bee78STejun Heo 583e22bee78STejun Heo /* this can only happen on the local cpu */ 584e22bee78STejun Heo BUG_ON(cpu != raw_smp_processor_id()); 585e22bee78STejun Heo 586e22bee78STejun Heo /* 587e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 588e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 589e22bee78STejun Heo * Please read comment there. 590e22bee78STejun Heo * 591e22bee78STejun Heo * NOT_RUNNING is clear. This means that trustee is not in 592e22bee78STejun Heo * charge and we're running on the local cpu w/ rq lock held 593e22bee78STejun Heo * and preemption disabled, which in turn means that none else 594e22bee78STejun Heo * could be manipulating idle_list, so dereferencing idle_list 595e22bee78STejun Heo * without gcwq lock is safe. 596e22bee78STejun Heo */ 597e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) 598e22bee78STejun Heo to_wakeup = first_worker(gcwq); 599e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 600e22bee78STejun Heo } 601e22bee78STejun Heo 602e22bee78STejun Heo /** 603e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 604cb444766STejun Heo * @worker: self 605d302f017STejun Heo * @flags: flags to set 606d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 607d302f017STejun Heo * 608e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 609e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 610e22bee78STejun Heo * woken up. 611d302f017STejun Heo * 612cb444766STejun Heo * CONTEXT: 613cb444766STejun Heo * spin_lock_irq(gcwq->lock) 614d302f017STejun Heo */ 615d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 616d302f017STejun Heo bool wakeup) 617d302f017STejun Heo { 618e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 619e22bee78STejun Heo 620cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 621cb444766STejun Heo 622e22bee78STejun Heo /* 623e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 624e22bee78STejun Heo * wake up an idle worker as necessary if requested by 625e22bee78STejun Heo * @wakeup. 626e22bee78STejun Heo */ 627e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 628e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 629e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 630e22bee78STejun Heo 631e22bee78STejun Heo if (wakeup) { 632e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && 633e22bee78STejun Heo !list_empty(&gcwq->worklist)) 634e22bee78STejun Heo wake_up_worker(gcwq); 635e22bee78STejun Heo } else 636e22bee78STejun Heo atomic_dec(nr_running); 637e22bee78STejun Heo } 638e22bee78STejun Heo 639d302f017STejun Heo worker->flags |= flags; 640d302f017STejun Heo } 641d302f017STejun Heo 642d302f017STejun Heo /** 643e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 644cb444766STejun Heo * @worker: self 645d302f017STejun Heo * @flags: flags to clear 646d302f017STejun Heo * 647e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 648d302f017STejun Heo * 649cb444766STejun Heo * CONTEXT: 650cb444766STejun Heo * spin_lock_irq(gcwq->lock) 651d302f017STejun Heo */ 652d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 653d302f017STejun Heo { 654e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 655e22bee78STejun Heo unsigned int oflags = worker->flags; 656e22bee78STejun Heo 657cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 658cb444766STejun Heo 659d302f017STejun Heo worker->flags &= ~flags; 660e22bee78STejun Heo 661e22bee78STejun Heo /* if transitioning out of NOT_RUNNING, increment nr_running */ 662e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 663e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 664e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(gcwq->cpu)); 665d302f017STejun Heo } 666d302f017STejun Heo 667d302f017STejun Heo /** 668c8e55f36STejun Heo * busy_worker_head - return the busy hash head for a work 669c8e55f36STejun Heo * @gcwq: gcwq of interest 670c8e55f36STejun Heo * @work: work to be hashed 671c8e55f36STejun Heo * 672c8e55f36STejun Heo * Return hash head of @gcwq for @work. 673c8e55f36STejun Heo * 674c8e55f36STejun Heo * CONTEXT: 675c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 676c8e55f36STejun Heo * 677c8e55f36STejun Heo * RETURNS: 678c8e55f36STejun Heo * Pointer to the hash head. 679c8e55f36STejun Heo */ 680c8e55f36STejun Heo static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, 681c8e55f36STejun Heo struct work_struct *work) 682c8e55f36STejun Heo { 683c8e55f36STejun Heo const int base_shift = ilog2(sizeof(struct work_struct)); 684c8e55f36STejun Heo unsigned long v = (unsigned long)work; 685c8e55f36STejun Heo 686c8e55f36STejun Heo /* simple shift and fold hash, do we need something better? */ 687c8e55f36STejun Heo v >>= base_shift; 688c8e55f36STejun Heo v += v >> BUSY_WORKER_HASH_ORDER; 689c8e55f36STejun Heo v &= BUSY_WORKER_HASH_MASK; 690c8e55f36STejun Heo 691c8e55f36STejun Heo return &gcwq->busy_hash[v]; 692c8e55f36STejun Heo } 693c8e55f36STejun Heo 694c8e55f36STejun Heo /** 6958cca0eeaSTejun Heo * __find_worker_executing_work - find worker which is executing a work 6968cca0eeaSTejun Heo * @gcwq: gcwq of interest 6978cca0eeaSTejun Heo * @bwh: hash head as returned by busy_worker_head() 6988cca0eeaSTejun Heo * @work: work to find worker for 6998cca0eeaSTejun Heo * 7008cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. @bwh should be 7018cca0eeaSTejun Heo * the hash head obtained by calling busy_worker_head() with the same 7028cca0eeaSTejun Heo * work. 7038cca0eeaSTejun Heo * 7048cca0eeaSTejun Heo * CONTEXT: 7058cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 7068cca0eeaSTejun Heo * 7078cca0eeaSTejun Heo * RETURNS: 7088cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 7098cca0eeaSTejun Heo * otherwise. 7108cca0eeaSTejun Heo */ 7118cca0eeaSTejun Heo static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, 7128cca0eeaSTejun Heo struct hlist_head *bwh, 7138cca0eeaSTejun Heo struct work_struct *work) 7148cca0eeaSTejun Heo { 7158cca0eeaSTejun Heo struct worker *worker; 7168cca0eeaSTejun Heo struct hlist_node *tmp; 7178cca0eeaSTejun Heo 7188cca0eeaSTejun Heo hlist_for_each_entry(worker, tmp, bwh, hentry) 7198cca0eeaSTejun Heo if (worker->current_work == work) 7208cca0eeaSTejun Heo return worker; 7218cca0eeaSTejun Heo return NULL; 7228cca0eeaSTejun Heo } 7238cca0eeaSTejun Heo 7248cca0eeaSTejun Heo /** 7258cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 7268cca0eeaSTejun Heo * @gcwq: gcwq of interest 7278cca0eeaSTejun Heo * @work: work to find worker for 7288cca0eeaSTejun Heo * 7298cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. This function is 7308cca0eeaSTejun Heo * identical to __find_worker_executing_work() except that this 7318cca0eeaSTejun Heo * function calculates @bwh itself. 7328cca0eeaSTejun Heo * 7338cca0eeaSTejun Heo * CONTEXT: 7348cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 7358cca0eeaSTejun Heo * 7368cca0eeaSTejun Heo * RETURNS: 7378cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 7388cca0eeaSTejun Heo * otherwise. 7398cca0eeaSTejun Heo */ 7408cca0eeaSTejun Heo static struct worker *find_worker_executing_work(struct global_cwq *gcwq, 7418cca0eeaSTejun Heo struct work_struct *work) 7428cca0eeaSTejun Heo { 7438cca0eeaSTejun Heo return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), 7448cca0eeaSTejun Heo work); 7458cca0eeaSTejun Heo } 7468cca0eeaSTejun Heo 7478cca0eeaSTejun Heo /** 748649027d7STejun Heo * gcwq_determine_ins_pos - find insertion position 749649027d7STejun Heo * @gcwq: gcwq of interest 750649027d7STejun Heo * @cwq: cwq a work is being queued for 751649027d7STejun Heo * 752649027d7STejun Heo * A work for @cwq is about to be queued on @gcwq, determine insertion 753649027d7STejun Heo * position for the work. If @cwq is for HIGHPRI wq, the work is 754649027d7STejun Heo * queued at the head of the queue but in FIFO order with respect to 755649027d7STejun Heo * other HIGHPRI works; otherwise, at the end of the queue. This 756649027d7STejun Heo * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that 757649027d7STejun Heo * there are HIGHPRI works pending. 758649027d7STejun Heo * 759649027d7STejun Heo * CONTEXT: 760649027d7STejun Heo * spin_lock_irq(gcwq->lock). 761649027d7STejun Heo * 762649027d7STejun Heo * RETURNS: 763649027d7STejun Heo * Pointer to inserstion position. 764649027d7STejun Heo */ 765649027d7STejun Heo static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, 766649027d7STejun Heo struct cpu_workqueue_struct *cwq) 767649027d7STejun Heo { 768649027d7STejun Heo struct work_struct *twork; 769649027d7STejun Heo 770649027d7STejun Heo if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) 771649027d7STejun Heo return &gcwq->worklist; 772649027d7STejun Heo 773649027d7STejun Heo list_for_each_entry(twork, &gcwq->worklist, entry) { 774649027d7STejun Heo struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); 775649027d7STejun Heo 776649027d7STejun Heo if (!(tcwq->wq->flags & WQ_HIGHPRI)) 777649027d7STejun Heo break; 778649027d7STejun Heo } 779649027d7STejun Heo 780649027d7STejun Heo gcwq->flags |= GCWQ_HIGHPRI_PENDING; 781649027d7STejun Heo return &twork->entry; 782649027d7STejun Heo } 783649027d7STejun Heo 784649027d7STejun Heo /** 7857e11629dSTejun Heo * insert_work - insert a work into gcwq 7864690c4abSTejun Heo * @cwq: cwq @work belongs to 7874690c4abSTejun Heo * @work: work to insert 7884690c4abSTejun Heo * @head: insertion point 7894690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 7904690c4abSTejun Heo * 7917e11629dSTejun Heo * Insert @work which belongs to @cwq into @gcwq after @head. 7927e11629dSTejun Heo * @extra_flags is or'd to work_struct flags. 7934690c4abSTejun Heo * 7944690c4abSTejun Heo * CONTEXT: 7958b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 7964690c4abSTejun Heo */ 797b89deed3SOleg Nesterov static void insert_work(struct cpu_workqueue_struct *cwq, 7984690c4abSTejun Heo struct work_struct *work, struct list_head *head, 7994690c4abSTejun Heo unsigned int extra_flags) 800b89deed3SOleg Nesterov { 801e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 802e22bee78STejun Heo 8034690c4abSTejun Heo /* we own @work, set data and link */ 8047a22ad75STejun Heo set_work_cwq(work, cwq, extra_flags); 8054690c4abSTejun Heo 8066e84d644SOleg Nesterov /* 8076e84d644SOleg Nesterov * Ensure that we get the right work->data if we see the 8086e84d644SOleg Nesterov * result of list_add() below, see try_to_grab_pending(). 8096e84d644SOleg Nesterov */ 8106e84d644SOleg Nesterov smp_wmb(); 8114690c4abSTejun Heo 8121a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 813e22bee78STejun Heo 814e22bee78STejun Heo /* 815e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 816e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 817e22bee78STejun Heo * lying around lazily while there are works to be processed. 818e22bee78STejun Heo */ 819e22bee78STejun Heo smp_mb(); 820e22bee78STejun Heo 821649027d7STejun Heo if (__need_more_worker(gcwq)) 822e22bee78STejun Heo wake_up_worker(gcwq); 823b89deed3SOleg Nesterov } 824b89deed3SOleg Nesterov 825502ca9d8STejun Heo /** 826502ca9d8STejun Heo * cwq_unbind_single_cpu - unbind cwq from single cpu workqueue processing 827502ca9d8STejun Heo * @cwq: cwq to unbind 828502ca9d8STejun Heo * 829502ca9d8STejun Heo * Try to unbind @cwq from single cpu workqueue processing. If 830502ca9d8STejun Heo * @cwq->wq is frozen, unbind is delayed till the workqueue is thawed. 831502ca9d8STejun Heo * 832502ca9d8STejun Heo * CONTEXT: 833502ca9d8STejun Heo * spin_lock_irq(gcwq->lock). 834502ca9d8STejun Heo */ 835502ca9d8STejun Heo static void cwq_unbind_single_cpu(struct cpu_workqueue_struct *cwq) 836502ca9d8STejun Heo { 837502ca9d8STejun Heo struct workqueue_struct *wq = cwq->wq; 838502ca9d8STejun Heo struct global_cwq *gcwq = cwq->gcwq; 839502ca9d8STejun Heo 840502ca9d8STejun Heo BUG_ON(wq->single_cpu != gcwq->cpu); 841502ca9d8STejun Heo /* 842502ca9d8STejun Heo * Unbind from workqueue if @cwq is not frozen. If frozen, 843502ca9d8STejun Heo * thaw_workqueues() will either restart processing on this 844502ca9d8STejun Heo * cpu or unbind if empty. This keeps works queued while 845502ca9d8STejun Heo * frozen fully ordered and flushable. 846502ca9d8STejun Heo */ 847502ca9d8STejun Heo if (likely(!(gcwq->flags & GCWQ_FREEZING))) { 848502ca9d8STejun Heo smp_wmb(); /* paired with cmpxchg() in __queue_work() */ 849502ca9d8STejun Heo wq->single_cpu = NR_CPUS; 850502ca9d8STejun Heo } 851502ca9d8STejun Heo } 852502ca9d8STejun Heo 8534690c4abSTejun Heo static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 8541da177e4SLinus Torvalds struct work_struct *work) 8551da177e4SLinus Torvalds { 856502ca9d8STejun Heo struct global_cwq *gcwq; 857502ca9d8STejun Heo struct cpu_workqueue_struct *cwq; 8581e19ffc6STejun Heo struct list_head *worklist; 8591da177e4SLinus Torvalds unsigned long flags; 860502ca9d8STejun Heo bool arbitrate; 8611da177e4SLinus Torvalds 862dc186ad7SThomas Gleixner debug_work_activate(work); 8631e19ffc6STejun Heo 86418aa9effSTejun Heo /* 86518aa9effSTejun Heo * Determine gcwq to use. SINGLE_CPU is inherently 86618aa9effSTejun Heo * NON_REENTRANT, so test it first. 86718aa9effSTejun Heo */ 868502ca9d8STejun Heo if (!(wq->flags & WQ_SINGLE_CPU)) { 86918aa9effSTejun Heo struct global_cwq *last_gcwq; 87018aa9effSTejun Heo 87118aa9effSTejun Heo /* 87218aa9effSTejun Heo * It's multi cpu. If @wq is non-reentrant and @work 87318aa9effSTejun Heo * was previously on a different cpu, it might still 87418aa9effSTejun Heo * be running there, in which case the work needs to 87518aa9effSTejun Heo * be queued on that cpu to guarantee non-reentrance. 87618aa9effSTejun Heo */ 877502ca9d8STejun Heo gcwq = get_gcwq(cpu); 87818aa9effSTejun Heo if (wq->flags & WQ_NON_REENTRANT && 87918aa9effSTejun Heo (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { 88018aa9effSTejun Heo struct worker *worker; 88118aa9effSTejun Heo 88218aa9effSTejun Heo spin_lock_irqsave(&last_gcwq->lock, flags); 88318aa9effSTejun Heo 88418aa9effSTejun Heo worker = find_worker_executing_work(last_gcwq, work); 88518aa9effSTejun Heo 88618aa9effSTejun Heo if (worker && worker->current_cwq->wq == wq) 88718aa9effSTejun Heo gcwq = last_gcwq; 88818aa9effSTejun Heo else { 88918aa9effSTejun Heo /* meh... not running there, queue here */ 89018aa9effSTejun Heo spin_unlock_irqrestore(&last_gcwq->lock, flags); 89118aa9effSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 89218aa9effSTejun Heo } 89318aa9effSTejun Heo } else 8948b03ae3cSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 895502ca9d8STejun Heo } else { 896502ca9d8STejun Heo unsigned int req_cpu = cpu; 897502ca9d8STejun Heo 898502ca9d8STejun Heo /* 899502ca9d8STejun Heo * It's a bit more complex for single cpu workqueues. 900502ca9d8STejun Heo * We first need to determine which cpu is going to be 901502ca9d8STejun Heo * used. If no cpu is currently serving this 902502ca9d8STejun Heo * workqueue, arbitrate using atomic accesses to 903502ca9d8STejun Heo * wq->single_cpu; otherwise, use the current one. 904502ca9d8STejun Heo */ 905502ca9d8STejun Heo retry: 906502ca9d8STejun Heo cpu = wq->single_cpu; 907502ca9d8STejun Heo arbitrate = cpu == NR_CPUS; 908502ca9d8STejun Heo if (arbitrate) 909502ca9d8STejun Heo cpu = req_cpu; 910502ca9d8STejun Heo 911502ca9d8STejun Heo gcwq = get_gcwq(cpu); 912502ca9d8STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 913502ca9d8STejun Heo 914502ca9d8STejun Heo /* 915502ca9d8STejun Heo * The following cmpxchg() is a full barrier paired 916502ca9d8STejun Heo * with smp_wmb() in cwq_unbind_single_cpu() and 917502ca9d8STejun Heo * guarantees that all changes to wq->st_* fields are 918502ca9d8STejun Heo * visible on the new cpu after this point. 919502ca9d8STejun Heo */ 920502ca9d8STejun Heo if (arbitrate) 921502ca9d8STejun Heo cmpxchg(&wq->single_cpu, NR_CPUS, cpu); 922502ca9d8STejun Heo 923502ca9d8STejun Heo if (unlikely(wq->single_cpu != cpu)) { 924502ca9d8STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 925502ca9d8STejun Heo goto retry; 926502ca9d8STejun Heo } 927502ca9d8STejun Heo } 928502ca9d8STejun Heo 929502ca9d8STejun Heo /* gcwq determined, get cwq and queue */ 930502ca9d8STejun Heo cwq = get_cwq(gcwq->cpu, wq); 931502ca9d8STejun Heo 9324690c4abSTejun Heo BUG_ON(!list_empty(&work->entry)); 9331e19ffc6STejun Heo 93473f53c4aSTejun Heo cwq->nr_in_flight[cwq->work_color]++; 9351e19ffc6STejun Heo 9361e19ffc6STejun Heo if (likely(cwq->nr_active < cwq->max_active)) { 9371e19ffc6STejun Heo cwq->nr_active++; 938649027d7STejun Heo worklist = gcwq_determine_ins_pos(gcwq, cwq); 9391e19ffc6STejun Heo } else 9401e19ffc6STejun Heo worklist = &cwq->delayed_works; 9411e19ffc6STejun Heo 9421e19ffc6STejun Heo insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color)); 9431e19ffc6STejun Heo 9448b03ae3cSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 9451da177e4SLinus Torvalds } 9461da177e4SLinus Torvalds 9470fcb78c2SRolf Eike Beer /** 9480fcb78c2SRolf Eike Beer * queue_work - queue work on a workqueue 9490fcb78c2SRolf Eike Beer * @wq: workqueue to use 9500fcb78c2SRolf Eike Beer * @work: work to queue 9510fcb78c2SRolf Eike Beer * 952057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 9531da177e4SLinus Torvalds * 95400dfcaf7SOleg Nesterov * We queue the work to the CPU on which it was submitted, but if the CPU dies 95500dfcaf7SOleg Nesterov * it can be processed by another CPU. 9561da177e4SLinus Torvalds */ 9577ad5b3a5SHarvey Harrison int queue_work(struct workqueue_struct *wq, struct work_struct *work) 9581da177e4SLinus Torvalds { 959ef1ca236SOleg Nesterov int ret; 9601da177e4SLinus Torvalds 961ef1ca236SOleg Nesterov ret = queue_work_on(get_cpu(), wq, work); 962a848e3b6SOleg Nesterov put_cpu(); 963ef1ca236SOleg Nesterov 9641da177e4SLinus Torvalds return ret; 9651da177e4SLinus Torvalds } 966ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_work); 9671da177e4SLinus Torvalds 968c1a220e7SZhang Rui /** 969c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 970c1a220e7SZhang Rui * @cpu: CPU number to execute work on 971c1a220e7SZhang Rui * @wq: workqueue to use 972c1a220e7SZhang Rui * @work: work to queue 973c1a220e7SZhang Rui * 974c1a220e7SZhang Rui * Returns 0 if @work was already on a queue, non-zero otherwise. 975c1a220e7SZhang Rui * 976c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 977c1a220e7SZhang Rui * can't go away. 978c1a220e7SZhang Rui */ 979c1a220e7SZhang Rui int 980c1a220e7SZhang Rui queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) 981c1a220e7SZhang Rui { 982c1a220e7SZhang Rui int ret = 0; 983c1a220e7SZhang Rui 98422df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 9854690c4abSTejun Heo __queue_work(cpu, wq, work); 986c1a220e7SZhang Rui ret = 1; 987c1a220e7SZhang Rui } 988c1a220e7SZhang Rui return ret; 989c1a220e7SZhang Rui } 990c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 991c1a220e7SZhang Rui 9926d141c3fSLi Zefan static void delayed_work_timer_fn(unsigned long __data) 9931da177e4SLinus Torvalds { 99452bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 9957a22ad75STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); 9961da177e4SLinus Torvalds 9974690c4abSTejun Heo __queue_work(smp_processor_id(), cwq->wq, &dwork->work); 9981da177e4SLinus Torvalds } 9991da177e4SLinus Torvalds 10000fcb78c2SRolf Eike Beer /** 10010fcb78c2SRolf Eike Beer * queue_delayed_work - queue work on a workqueue after delay 10020fcb78c2SRolf Eike Beer * @wq: workqueue to use 1003af9997e4SRandy Dunlap * @dwork: delayable work to queue 10040fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10050fcb78c2SRolf Eike Beer * 1006057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10070fcb78c2SRolf Eike Beer */ 10087ad5b3a5SHarvey Harrison int queue_delayed_work(struct workqueue_struct *wq, 100952bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 10101da177e4SLinus Torvalds { 101152bad64dSDavid Howells if (delay == 0) 101263bc0362SOleg Nesterov return queue_work(wq, &dwork->work); 10131da177e4SLinus Torvalds 101463bc0362SOleg Nesterov return queue_delayed_work_on(-1, wq, dwork, delay); 10151da177e4SLinus Torvalds } 1016ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work); 10171da177e4SLinus Torvalds 10180fcb78c2SRolf Eike Beer /** 10190fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 10200fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 10210fcb78c2SRolf Eike Beer * @wq: workqueue to use 1022af9997e4SRandy Dunlap * @dwork: work to queue 10230fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10240fcb78c2SRolf Eike Beer * 1025057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10260fcb78c2SRolf Eike Beer */ 10277a6bc1cdSVenkatesh Pallipadi int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 102852bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 10297a6bc1cdSVenkatesh Pallipadi { 10307a6bc1cdSVenkatesh Pallipadi int ret = 0; 103152bad64dSDavid Howells struct timer_list *timer = &dwork->timer; 103252bad64dSDavid Howells struct work_struct *work = &dwork->work; 10337a6bc1cdSVenkatesh Pallipadi 103422df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 10357a22ad75STejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 10367a22ad75STejun Heo unsigned int lcpu = gcwq ? gcwq->cpu : raw_smp_processor_id(); 10377a22ad75STejun Heo 10387a6bc1cdSVenkatesh Pallipadi BUG_ON(timer_pending(timer)); 10397a6bc1cdSVenkatesh Pallipadi BUG_ON(!list_empty(&work->entry)); 10407a6bc1cdSVenkatesh Pallipadi 10418a3e77ccSAndrew Liu timer_stats_timer_set_start_info(&dwork->timer); 10427a22ad75STejun Heo /* 10437a22ad75STejun Heo * This stores cwq for the moment, for the timer_fn. 10447a22ad75STejun Heo * Note that the work's gcwq is preserved to allow 10457a22ad75STejun Heo * reentrance detection for delayed works. 10467a22ad75STejun Heo */ 10477a22ad75STejun Heo set_work_cwq(work, get_cwq(lcpu, wq), 0); 10487a6bc1cdSVenkatesh Pallipadi timer->expires = jiffies + delay; 104952bad64dSDavid Howells timer->data = (unsigned long)dwork; 10507a6bc1cdSVenkatesh Pallipadi timer->function = delayed_work_timer_fn; 105163bc0362SOleg Nesterov 105263bc0362SOleg Nesterov if (unlikely(cpu >= 0)) 10537a6bc1cdSVenkatesh Pallipadi add_timer_on(timer, cpu); 105463bc0362SOleg Nesterov else 105563bc0362SOleg Nesterov add_timer(timer); 10567a6bc1cdSVenkatesh Pallipadi ret = 1; 10577a6bc1cdSVenkatesh Pallipadi } 10587a6bc1cdSVenkatesh Pallipadi return ret; 10597a6bc1cdSVenkatesh Pallipadi } 1060ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 10611da177e4SLinus Torvalds 1062c8e55f36STejun Heo /** 1063c8e55f36STejun Heo * worker_enter_idle - enter idle state 1064c8e55f36STejun Heo * @worker: worker which is entering idle state 1065c8e55f36STejun Heo * 1066c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1067c8e55f36STejun Heo * necessary. 1068c8e55f36STejun Heo * 1069c8e55f36STejun Heo * LOCKING: 1070c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1071c8e55f36STejun Heo */ 1072c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 1073c8e55f36STejun Heo { 1074c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1075c8e55f36STejun Heo 1076c8e55f36STejun Heo BUG_ON(worker->flags & WORKER_IDLE); 1077c8e55f36STejun Heo BUG_ON(!list_empty(&worker->entry) && 1078c8e55f36STejun Heo (worker->hentry.next || worker->hentry.pprev)); 1079c8e55f36STejun Heo 1080cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1081cb444766STejun Heo worker->flags |= WORKER_IDLE; 1082c8e55f36STejun Heo gcwq->nr_idle++; 1083e22bee78STejun Heo worker->last_active = jiffies; 1084c8e55f36STejun Heo 1085c8e55f36STejun Heo /* idle_list is LIFO */ 1086c8e55f36STejun Heo list_add(&worker->entry, &gcwq->idle_list); 1087db7bccf4STejun Heo 1088e22bee78STejun Heo if (likely(!(worker->flags & WORKER_ROGUE))) { 1089e22bee78STejun Heo if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) 1090e22bee78STejun Heo mod_timer(&gcwq->idle_timer, 1091e22bee78STejun Heo jiffies + IDLE_WORKER_TIMEOUT); 1092e22bee78STejun Heo } else 1093db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 1094cb444766STejun Heo 1095cb444766STejun Heo /* sanity check nr_running */ 1096cb444766STejun Heo WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && 1097cb444766STejun Heo atomic_read(get_gcwq_nr_running(gcwq->cpu))); 1098c8e55f36STejun Heo } 1099c8e55f36STejun Heo 1100c8e55f36STejun Heo /** 1101c8e55f36STejun Heo * worker_leave_idle - leave idle state 1102c8e55f36STejun Heo * @worker: worker which is leaving idle state 1103c8e55f36STejun Heo * 1104c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1105c8e55f36STejun Heo * 1106c8e55f36STejun Heo * LOCKING: 1107c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1108c8e55f36STejun Heo */ 1109c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1110c8e55f36STejun Heo { 1111c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1112c8e55f36STejun Heo 1113c8e55f36STejun Heo BUG_ON(!(worker->flags & WORKER_IDLE)); 1114d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1115c8e55f36STejun Heo gcwq->nr_idle--; 1116c8e55f36STejun Heo list_del_init(&worker->entry); 1117c8e55f36STejun Heo } 1118c8e55f36STejun Heo 1119e22bee78STejun Heo /** 1120e22bee78STejun Heo * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq 1121e22bee78STejun Heo * @worker: self 1122e22bee78STejun Heo * 1123e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1124e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1125e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1126e22bee78STejun Heo * guaranteed to execute on the cpu. 1127e22bee78STejun Heo * 1128e22bee78STejun Heo * This function is to be used by rogue workers and rescuers to bind 1129e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1130e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1131e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1132e22bee78STejun Heo * verbatim as it's best effort and blocking and gcwq may be 1133e22bee78STejun Heo * [dis]associated in the meantime. 1134e22bee78STejun Heo * 1135e22bee78STejun Heo * This function tries set_cpus_allowed() and locks gcwq and verifies 1136e22bee78STejun Heo * the binding against GCWQ_DISASSOCIATED which is set during 1137e22bee78STejun Heo * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters 1138e22bee78STejun Heo * idle state or fetches works without dropping lock, it can guarantee 1139e22bee78STejun Heo * the scheduling requirement described in the first paragraph. 1140e22bee78STejun Heo * 1141e22bee78STejun Heo * CONTEXT: 1142e22bee78STejun Heo * Might sleep. Called without any lock but returns with gcwq->lock 1143e22bee78STejun Heo * held. 1144e22bee78STejun Heo * 1145e22bee78STejun Heo * RETURNS: 1146e22bee78STejun Heo * %true if the associated gcwq is online (@worker is successfully 1147e22bee78STejun Heo * bound), %false if offline. 1148e22bee78STejun Heo */ 1149e22bee78STejun Heo static bool worker_maybe_bind_and_lock(struct worker *worker) 1150e22bee78STejun Heo { 1151e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1152e22bee78STejun Heo struct task_struct *task = worker->task; 1153e22bee78STejun Heo 1154e22bee78STejun Heo while (true) { 1155e22bee78STejun Heo /* 1156e22bee78STejun Heo * The following call may fail, succeed or succeed 1157e22bee78STejun Heo * without actually migrating the task to the cpu if 1158e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 1159e22bee78STejun Heo * against GCWQ_DISASSOCIATED. 1160e22bee78STejun Heo */ 1161e22bee78STejun Heo set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); 1162e22bee78STejun Heo 1163e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1164e22bee78STejun Heo if (gcwq->flags & GCWQ_DISASSOCIATED) 1165e22bee78STejun Heo return false; 1166e22bee78STejun Heo if (task_cpu(task) == gcwq->cpu && 1167e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1168e22bee78STejun Heo get_cpu_mask(gcwq->cpu))) 1169e22bee78STejun Heo return true; 1170e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1171e22bee78STejun Heo 1172e22bee78STejun Heo /* CPU has come up inbetween, retry migration */ 1173e22bee78STejun Heo cpu_relax(); 1174e22bee78STejun Heo } 1175e22bee78STejun Heo } 1176e22bee78STejun Heo 1177e22bee78STejun Heo /* 1178e22bee78STejun Heo * Function for worker->rebind_work used to rebind rogue busy workers 1179e22bee78STejun Heo * to the associated cpu which is coming back online. This is 1180e22bee78STejun Heo * scheduled by cpu up but can race with other cpu hotplug operations 1181e22bee78STejun Heo * and may be executed twice without intervening cpu down. 1182e22bee78STejun Heo */ 1183e22bee78STejun Heo static void worker_rebind_fn(struct work_struct *work) 1184e22bee78STejun Heo { 1185e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1186e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1187e22bee78STejun Heo 1188e22bee78STejun Heo if (worker_maybe_bind_and_lock(worker)) 1189e22bee78STejun Heo worker_clr_flags(worker, WORKER_REBIND); 1190e22bee78STejun Heo 1191e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1192e22bee78STejun Heo } 1193e22bee78STejun Heo 1194c34056a3STejun Heo static struct worker *alloc_worker(void) 1195c34056a3STejun Heo { 1196c34056a3STejun Heo struct worker *worker; 1197c34056a3STejun Heo 1198c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1199c8e55f36STejun Heo if (worker) { 1200c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1201affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1202e22bee78STejun Heo INIT_WORK(&worker->rebind_work, worker_rebind_fn); 1203e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1204e22bee78STejun Heo worker->flags = WORKER_PREP; 1205c8e55f36STejun Heo } 1206c34056a3STejun Heo return worker; 1207c34056a3STejun Heo } 1208c34056a3STejun Heo 1209c34056a3STejun Heo /** 1210c34056a3STejun Heo * create_worker - create a new workqueue worker 12117e11629dSTejun Heo * @gcwq: gcwq the new worker will belong to 1212c34056a3STejun Heo * @bind: whether to set affinity to @cpu or not 1213c34056a3STejun Heo * 12147e11629dSTejun Heo * Create a new worker which is bound to @gcwq. The returned worker 1215c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1216c34056a3STejun Heo * destroy_worker(). 1217c34056a3STejun Heo * 1218c34056a3STejun Heo * CONTEXT: 1219c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1220c34056a3STejun Heo * 1221c34056a3STejun Heo * RETURNS: 1222c34056a3STejun Heo * Pointer to the newly created worker. 1223c34056a3STejun Heo */ 12247e11629dSTejun Heo static struct worker *create_worker(struct global_cwq *gcwq, bool bind) 1225c34056a3STejun Heo { 1226c34056a3STejun Heo int id = -1; 1227c34056a3STejun Heo struct worker *worker = NULL; 1228c34056a3STejun Heo 12298b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 12308b03ae3cSTejun Heo while (ida_get_new(&gcwq->worker_ida, &id)) { 12318b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 12328b03ae3cSTejun Heo if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) 1233c34056a3STejun Heo goto fail; 12348b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1235c34056a3STejun Heo } 12368b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1237c34056a3STejun Heo 1238c34056a3STejun Heo worker = alloc_worker(); 1239c34056a3STejun Heo if (!worker) 1240c34056a3STejun Heo goto fail; 1241c34056a3STejun Heo 12428b03ae3cSTejun Heo worker->gcwq = gcwq; 1243c34056a3STejun Heo worker->id = id; 1244c34056a3STejun Heo 1245c34056a3STejun Heo worker->task = kthread_create(worker_thread, worker, "kworker/%u:%d", 12468b03ae3cSTejun Heo gcwq->cpu, id); 1247c34056a3STejun Heo if (IS_ERR(worker->task)) 1248c34056a3STejun Heo goto fail; 1249c34056a3STejun Heo 1250db7bccf4STejun Heo /* 1251db7bccf4STejun Heo * A rogue worker will become a regular one if CPU comes 1252db7bccf4STejun Heo * online later on. Make sure every worker has 1253db7bccf4STejun Heo * PF_THREAD_BOUND set. 1254db7bccf4STejun Heo */ 1255c34056a3STejun Heo if (bind) 12568b03ae3cSTejun Heo kthread_bind(worker->task, gcwq->cpu); 1257db7bccf4STejun Heo else 1258db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1259c34056a3STejun Heo 1260c34056a3STejun Heo return worker; 1261c34056a3STejun Heo fail: 1262c34056a3STejun Heo if (id >= 0) { 12638b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 12648b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 12658b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1266c34056a3STejun Heo } 1267c34056a3STejun Heo kfree(worker); 1268c34056a3STejun Heo return NULL; 1269c34056a3STejun Heo } 1270c34056a3STejun Heo 1271c34056a3STejun Heo /** 1272c34056a3STejun Heo * start_worker - start a newly created worker 1273c34056a3STejun Heo * @worker: worker to start 1274c34056a3STejun Heo * 1275c8e55f36STejun Heo * Make the gcwq aware of @worker and start it. 1276c34056a3STejun Heo * 1277c34056a3STejun Heo * CONTEXT: 12788b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1279c34056a3STejun Heo */ 1280c34056a3STejun Heo static void start_worker(struct worker *worker) 1281c34056a3STejun Heo { 1282cb444766STejun Heo worker->flags |= WORKER_STARTED; 1283c8e55f36STejun Heo worker->gcwq->nr_workers++; 1284c8e55f36STejun Heo worker_enter_idle(worker); 1285c34056a3STejun Heo wake_up_process(worker->task); 1286c34056a3STejun Heo } 1287c34056a3STejun Heo 1288c34056a3STejun Heo /** 1289c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1290c34056a3STejun Heo * @worker: worker to be destroyed 1291c34056a3STejun Heo * 1292c8e55f36STejun Heo * Destroy @worker and adjust @gcwq stats accordingly. 1293c8e55f36STejun Heo * 1294c8e55f36STejun Heo * CONTEXT: 1295c8e55f36STejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1296c34056a3STejun Heo */ 1297c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1298c34056a3STejun Heo { 12998b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 1300c34056a3STejun Heo int id = worker->id; 1301c34056a3STejun Heo 1302c34056a3STejun Heo /* sanity check frenzy */ 1303c34056a3STejun Heo BUG_ON(worker->current_work); 1304affee4b2STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1305c34056a3STejun Heo 1306c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1307c8e55f36STejun Heo gcwq->nr_workers--; 1308c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1309c8e55f36STejun Heo gcwq->nr_idle--; 1310c8e55f36STejun Heo 1311c8e55f36STejun Heo list_del_init(&worker->entry); 1312cb444766STejun Heo worker->flags |= WORKER_DIE; 1313c8e55f36STejun Heo 1314c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1315c8e55f36STejun Heo 1316c34056a3STejun Heo kthread_stop(worker->task); 1317c34056a3STejun Heo kfree(worker); 1318c34056a3STejun Heo 13198b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13208b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 1321c34056a3STejun Heo } 1322c34056a3STejun Heo 1323e22bee78STejun Heo static void idle_worker_timeout(unsigned long __gcwq) 1324e22bee78STejun Heo { 1325e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1326e22bee78STejun Heo 1327e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1328e22bee78STejun Heo 1329e22bee78STejun Heo if (too_many_workers(gcwq)) { 1330e22bee78STejun Heo struct worker *worker; 1331e22bee78STejun Heo unsigned long expires; 1332e22bee78STejun Heo 1333e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 1334e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1335e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1336e22bee78STejun Heo 1337e22bee78STejun Heo if (time_before(jiffies, expires)) 1338e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1339e22bee78STejun Heo else { 1340e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 1341e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 1342e22bee78STejun Heo wake_up_worker(gcwq); 1343e22bee78STejun Heo } 1344e22bee78STejun Heo } 1345e22bee78STejun Heo 1346e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1347e22bee78STejun Heo } 1348e22bee78STejun Heo 1349e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1350e22bee78STejun Heo { 1351e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1352e22bee78STejun Heo struct workqueue_struct *wq = cwq->wq; 1353e22bee78STejun Heo 1354e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1355e22bee78STejun Heo return false; 1356e22bee78STejun Heo 1357e22bee78STejun Heo /* mayday mayday mayday */ 1358e22bee78STejun Heo if (!cpumask_test_and_set_cpu(cwq->gcwq->cpu, wq->mayday_mask)) 1359e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1360e22bee78STejun Heo return true; 1361e22bee78STejun Heo } 1362e22bee78STejun Heo 1363e22bee78STejun Heo static void gcwq_mayday_timeout(unsigned long __gcwq) 1364e22bee78STejun Heo { 1365e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1366e22bee78STejun Heo struct work_struct *work; 1367e22bee78STejun Heo 1368e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1369e22bee78STejun Heo 1370e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 1371e22bee78STejun Heo /* 1372e22bee78STejun Heo * We've been trying to create a new worker but 1373e22bee78STejun Heo * haven't been successful. We might be hitting an 1374e22bee78STejun Heo * allocation deadlock. Send distress signals to 1375e22bee78STejun Heo * rescuers. 1376e22bee78STejun Heo */ 1377e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) 1378e22bee78STejun Heo send_mayday(work); 1379e22bee78STejun Heo } 1380e22bee78STejun Heo 1381e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1382e22bee78STejun Heo 1383e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); 1384e22bee78STejun Heo } 1385e22bee78STejun Heo 1386e22bee78STejun Heo /** 1387e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 1388e22bee78STejun Heo * @gcwq: gcwq to create a new worker for 1389e22bee78STejun Heo * 1390e22bee78STejun Heo * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to 1391e22bee78STejun Heo * have at least one idle worker on return from this function. If 1392e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 1393e22bee78STejun Heo * sent to all rescuers with works scheduled on @gcwq to resolve 1394e22bee78STejun Heo * possible allocation deadlock. 1395e22bee78STejun Heo * 1396e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1397e22bee78STejun Heo * may_start_working() true. 1398e22bee78STejun Heo * 1399e22bee78STejun Heo * LOCKING: 1400e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1401e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1402e22bee78STejun Heo * manager. 1403e22bee78STejun Heo * 1404e22bee78STejun Heo * RETURNS: 1405e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1406e22bee78STejun Heo * otherwise. 1407e22bee78STejun Heo */ 1408e22bee78STejun Heo static bool maybe_create_worker(struct global_cwq *gcwq) 1409e22bee78STejun Heo { 1410e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1411e22bee78STejun Heo return false; 1412e22bee78STejun Heo restart: 1413e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 1414e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1415e22bee78STejun Heo 1416e22bee78STejun Heo while (true) { 1417e22bee78STejun Heo struct worker *worker; 1418e22bee78STejun Heo 1419e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1420e22bee78STejun Heo 1421e22bee78STejun Heo worker = create_worker(gcwq, true); 1422e22bee78STejun Heo if (worker) { 1423e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1424e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1425e22bee78STejun Heo start_worker(worker); 1426e22bee78STejun Heo BUG_ON(need_to_create_worker(gcwq)); 1427e22bee78STejun Heo return true; 1428e22bee78STejun Heo } 1429e22bee78STejun Heo 1430e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1431e22bee78STejun Heo break; 1432e22bee78STejun Heo 1433e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1434e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1435e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 1436e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1437e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1438e22bee78STejun Heo break; 1439e22bee78STejun Heo } 1440e22bee78STejun Heo 1441e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1442e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1443e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1444e22bee78STejun Heo if (need_to_create_worker(gcwq)) 1445e22bee78STejun Heo goto restart; 1446e22bee78STejun Heo return true; 1447e22bee78STejun Heo } 1448e22bee78STejun Heo 1449e22bee78STejun Heo /** 1450e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 1451e22bee78STejun Heo * @gcwq: gcwq to destroy workers for 1452e22bee78STejun Heo * 1453e22bee78STejun Heo * Destroy @gcwq workers which have been idle for longer than 1454e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1455e22bee78STejun Heo * 1456e22bee78STejun Heo * LOCKING: 1457e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1458e22bee78STejun Heo * multiple times. Called only from manager. 1459e22bee78STejun Heo * 1460e22bee78STejun Heo * RETURNS: 1461e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1462e22bee78STejun Heo * otherwise. 1463e22bee78STejun Heo */ 1464e22bee78STejun Heo static bool maybe_destroy_workers(struct global_cwq *gcwq) 1465e22bee78STejun Heo { 1466e22bee78STejun Heo bool ret = false; 1467e22bee78STejun Heo 1468e22bee78STejun Heo while (too_many_workers(gcwq)) { 1469e22bee78STejun Heo struct worker *worker; 1470e22bee78STejun Heo unsigned long expires; 1471e22bee78STejun Heo 1472e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1473e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1474e22bee78STejun Heo 1475e22bee78STejun Heo if (time_before(jiffies, expires)) { 1476e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1477e22bee78STejun Heo break; 1478e22bee78STejun Heo } 1479e22bee78STejun Heo 1480e22bee78STejun Heo destroy_worker(worker); 1481e22bee78STejun Heo ret = true; 1482e22bee78STejun Heo } 1483e22bee78STejun Heo 1484e22bee78STejun Heo return ret; 1485e22bee78STejun Heo } 1486e22bee78STejun Heo 1487e22bee78STejun Heo /** 1488e22bee78STejun Heo * manage_workers - manage worker pool 1489e22bee78STejun Heo * @worker: self 1490e22bee78STejun Heo * 1491e22bee78STejun Heo * Assume the manager role and manage gcwq worker pool @worker belongs 1492e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 1493e22bee78STejun Heo * gcwq. The exclusion is handled automatically by this function. 1494e22bee78STejun Heo * 1495e22bee78STejun Heo * The caller can safely start processing works on false return. On 1496e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 1497e22bee78STejun Heo * and may_start_working() is true. 1498e22bee78STejun Heo * 1499e22bee78STejun Heo * CONTEXT: 1500e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1501e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 1502e22bee78STejun Heo * 1503e22bee78STejun Heo * RETURNS: 1504e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true if 1505e22bee78STejun Heo * some action was taken. 1506e22bee78STejun Heo */ 1507e22bee78STejun Heo static bool manage_workers(struct worker *worker) 1508e22bee78STejun Heo { 1509e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1510e22bee78STejun Heo bool ret = false; 1511e22bee78STejun Heo 1512e22bee78STejun Heo if (gcwq->flags & GCWQ_MANAGING_WORKERS) 1513e22bee78STejun Heo return ret; 1514e22bee78STejun Heo 1515e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGE_WORKERS; 1516e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 1517e22bee78STejun Heo 1518e22bee78STejun Heo /* 1519e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 1520e22bee78STejun Heo * on return. 1521e22bee78STejun Heo */ 1522e22bee78STejun Heo ret |= maybe_destroy_workers(gcwq); 1523e22bee78STejun Heo ret |= maybe_create_worker(gcwq); 1524e22bee78STejun Heo 1525e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 1526e22bee78STejun Heo 1527e22bee78STejun Heo /* 1528e22bee78STejun Heo * The trustee might be waiting to take over the manager 1529e22bee78STejun Heo * position, tell it we're done. 1530e22bee78STejun Heo */ 1531e22bee78STejun Heo if (unlikely(gcwq->trustee)) 1532e22bee78STejun Heo wake_up_all(&gcwq->trustee_wait); 1533e22bee78STejun Heo 1534e22bee78STejun Heo return ret; 1535e22bee78STejun Heo } 1536e22bee78STejun Heo 1537a62428c0STejun Heo /** 1538affee4b2STejun Heo * move_linked_works - move linked works to a list 1539affee4b2STejun Heo * @work: start of series of works to be scheduled 1540affee4b2STejun Heo * @head: target list to append @work to 1541affee4b2STejun Heo * @nextp: out paramter for nested worklist walking 1542affee4b2STejun Heo * 1543affee4b2STejun Heo * Schedule linked works starting from @work to @head. Work series to 1544affee4b2STejun Heo * be scheduled starts at @work and includes any consecutive work with 1545affee4b2STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 1546affee4b2STejun Heo * 1547affee4b2STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 1548affee4b2STejun Heo * the last scheduled work. This allows move_linked_works() to be 1549affee4b2STejun Heo * nested inside outer list_for_each_entry_safe(). 1550affee4b2STejun Heo * 1551affee4b2STejun Heo * CONTEXT: 15528b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1553affee4b2STejun Heo */ 1554affee4b2STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1555affee4b2STejun Heo struct work_struct **nextp) 1556affee4b2STejun Heo { 1557affee4b2STejun Heo struct work_struct *n; 1558affee4b2STejun Heo 1559affee4b2STejun Heo /* 1560affee4b2STejun Heo * Linked worklist will always end before the end of the list, 1561affee4b2STejun Heo * use NULL for list head. 1562affee4b2STejun Heo */ 1563affee4b2STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1564affee4b2STejun Heo list_move_tail(&work->entry, head); 1565affee4b2STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1566affee4b2STejun Heo break; 1567affee4b2STejun Heo } 1568affee4b2STejun Heo 1569affee4b2STejun Heo /* 1570affee4b2STejun Heo * If we're already inside safe list traversal and have moved 1571affee4b2STejun Heo * multiple works to the scheduled queue, the next position 1572affee4b2STejun Heo * needs to be updated. 1573affee4b2STejun Heo */ 1574affee4b2STejun Heo if (nextp) 1575affee4b2STejun Heo *nextp = n; 1576affee4b2STejun Heo } 1577affee4b2STejun Heo 15781e19ffc6STejun Heo static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) 15791e19ffc6STejun Heo { 15801e19ffc6STejun Heo struct work_struct *work = list_first_entry(&cwq->delayed_works, 15811e19ffc6STejun Heo struct work_struct, entry); 1582649027d7STejun Heo struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); 15831e19ffc6STejun Heo 1584649027d7STejun Heo move_linked_works(work, pos, NULL); 15851e19ffc6STejun Heo cwq->nr_active++; 15861e19ffc6STejun Heo } 15871e19ffc6STejun Heo 1588affee4b2STejun Heo /** 158973f53c4aSTejun Heo * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight 159073f53c4aSTejun Heo * @cwq: cwq of interest 159173f53c4aSTejun Heo * @color: color of work which left the queue 159273f53c4aSTejun Heo * 159373f53c4aSTejun Heo * A work either has completed or is removed from pending queue, 159473f53c4aSTejun Heo * decrement nr_in_flight of its cwq and handle workqueue flushing. 159573f53c4aSTejun Heo * 159673f53c4aSTejun Heo * CONTEXT: 15978b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 159873f53c4aSTejun Heo */ 159973f53c4aSTejun Heo static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) 160073f53c4aSTejun Heo { 160173f53c4aSTejun Heo /* ignore uncolored works */ 160273f53c4aSTejun Heo if (color == WORK_NO_COLOR) 160373f53c4aSTejun Heo return; 160473f53c4aSTejun Heo 160573f53c4aSTejun Heo cwq->nr_in_flight[color]--; 16061e19ffc6STejun Heo cwq->nr_active--; 16071e19ffc6STejun Heo 1608502ca9d8STejun Heo if (!list_empty(&cwq->delayed_works)) { 16091e19ffc6STejun Heo /* one down, submit a delayed one */ 1610502ca9d8STejun Heo if (cwq->nr_active < cwq->max_active) 16111e19ffc6STejun Heo cwq_activate_first_delayed(cwq); 1612502ca9d8STejun Heo } else if (!cwq->nr_active && cwq->wq->flags & WQ_SINGLE_CPU) { 1613502ca9d8STejun Heo /* this was the last work, unbind from single cpu */ 1614502ca9d8STejun Heo cwq_unbind_single_cpu(cwq); 1615502ca9d8STejun Heo } 161673f53c4aSTejun Heo 161773f53c4aSTejun Heo /* is flush in progress and are we at the flushing tip? */ 161873f53c4aSTejun Heo if (likely(cwq->flush_color != color)) 161973f53c4aSTejun Heo return; 162073f53c4aSTejun Heo 162173f53c4aSTejun Heo /* are there still in-flight works? */ 162273f53c4aSTejun Heo if (cwq->nr_in_flight[color]) 162373f53c4aSTejun Heo return; 162473f53c4aSTejun Heo 162573f53c4aSTejun Heo /* this cwq is done, clear flush_color */ 162673f53c4aSTejun Heo cwq->flush_color = -1; 162773f53c4aSTejun Heo 162873f53c4aSTejun Heo /* 162973f53c4aSTejun Heo * If this was the last cwq, wake up the first flusher. It 163073f53c4aSTejun Heo * will handle the rest. 163173f53c4aSTejun Heo */ 163273f53c4aSTejun Heo if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) 163373f53c4aSTejun Heo complete(&cwq->wq->first_flusher->done); 163473f53c4aSTejun Heo } 163573f53c4aSTejun Heo 163673f53c4aSTejun Heo /** 1637a62428c0STejun Heo * process_one_work - process single work 1638c34056a3STejun Heo * @worker: self 1639a62428c0STejun Heo * @work: work to process 1640a62428c0STejun Heo * 1641a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 1642a62428c0STejun Heo * process a single work including synchronization against and 1643a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 1644a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 1645a62428c0STejun Heo * call this function to process a work. 1646a62428c0STejun Heo * 1647a62428c0STejun Heo * CONTEXT: 16488b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1649a62428c0STejun Heo */ 1650c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 16511da177e4SLinus Torvalds { 16527e11629dSTejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 16538b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 1654c8e55f36STejun Heo struct hlist_head *bwh = busy_worker_head(gcwq, work); 1655fb0e7bebSTejun Heo bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 16566bb49e59SDavid Howells work_func_t f = work->func; 165773f53c4aSTejun Heo int work_color; 16587e11629dSTejun Heo struct worker *collision; 16594e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 16604e6045f1SJohannes Berg /* 1661a62428c0STejun Heo * It is permissible to free the struct work_struct from 1662a62428c0STejun Heo * inside the function that is called from it, this we need to 1663a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 1664a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 1665a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 16664e6045f1SJohannes Berg */ 16674e6045f1SJohannes Berg struct lockdep_map lockdep_map = work->lockdep_map; 16684e6045f1SJohannes Berg #endif 16697e11629dSTejun Heo /* 16707e11629dSTejun Heo * A single work shouldn't be executed concurrently by 16717e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 16727e11629dSTejun Heo * already processing the work. If so, defer the work to the 16737e11629dSTejun Heo * currently executing one. 16747e11629dSTejun Heo */ 16757e11629dSTejun Heo collision = __find_worker_executing_work(gcwq, bwh, work); 16767e11629dSTejun Heo if (unlikely(collision)) { 16777e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 16787e11629dSTejun Heo return; 16797e11629dSTejun Heo } 16807e11629dSTejun Heo 1681a62428c0STejun Heo /* claim and process */ 1682dc186ad7SThomas Gleixner debug_work_deactivate(work); 1683c8e55f36STejun Heo hlist_add_head(&worker->hentry, bwh); 1684c34056a3STejun Heo worker->current_work = work; 16858cca0eeaSTejun Heo worker->current_cwq = cwq; 168673f53c4aSTejun Heo work_color = get_work_color(work); 16877a22ad75STejun Heo 16887a22ad75STejun Heo /* record the current cpu number in the work data and dequeue */ 16897a22ad75STejun Heo set_work_cpu(work, gcwq->cpu); 1690a62428c0STejun Heo list_del_init(&work->entry); 1691a62428c0STejun Heo 1692649027d7STejun Heo /* 1693649027d7STejun Heo * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, 1694649027d7STejun Heo * wake up another worker; otherwise, clear HIGHPRI_PENDING. 1695649027d7STejun Heo */ 1696649027d7STejun Heo if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { 1697649027d7STejun Heo struct work_struct *nwork = list_first_entry(&gcwq->worklist, 1698649027d7STejun Heo struct work_struct, entry); 1699649027d7STejun Heo 1700649027d7STejun Heo if (!list_empty(&gcwq->worklist) && 1701649027d7STejun Heo get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) 1702649027d7STejun Heo wake_up_worker(gcwq); 1703649027d7STejun Heo else 1704649027d7STejun Heo gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; 1705649027d7STejun Heo } 1706649027d7STejun Heo 1707fb0e7bebSTejun Heo /* 1708fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 1709fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 1710fb0e7bebSTejun Heo */ 1711fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1712fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 1713fb0e7bebSTejun Heo 17148b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 17151da177e4SLinus Torvalds 171623b2e599SOleg Nesterov work_clear_pending(work); 17173295f0efSIngo Molnar lock_map_acquire(&cwq->wq->lockdep_map); 17183295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 171965f27f38SDavid Howells f(work); 17203295f0efSIngo Molnar lock_map_release(&lockdep_map); 17213295f0efSIngo Molnar lock_map_release(&cwq->wq->lockdep_map); 17221da177e4SLinus Torvalds 1723d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 1724d5abe669SPeter Zijlstra printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " 1725d5abe669SPeter Zijlstra "%s/0x%08x/%d\n", 1726a62428c0STejun Heo current->comm, preempt_count(), task_pid_nr(current)); 1727d5abe669SPeter Zijlstra printk(KERN_ERR " last function: "); 1728d5abe669SPeter Zijlstra print_symbol("%s\n", (unsigned long)f); 1729d5abe669SPeter Zijlstra debug_show_held_locks(current); 1730d5abe669SPeter Zijlstra dump_stack(); 1731d5abe669SPeter Zijlstra } 1732d5abe669SPeter Zijlstra 17338b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1734a62428c0STejun Heo 1735fb0e7bebSTejun Heo /* clear cpu intensive status */ 1736fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1737fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 1738fb0e7bebSTejun Heo 1739a62428c0STejun Heo /* we're done with it, release */ 1740c8e55f36STejun Heo hlist_del_init(&worker->hentry); 1741c34056a3STejun Heo worker->current_work = NULL; 17428cca0eeaSTejun Heo worker->current_cwq = NULL; 174373f53c4aSTejun Heo cwq_dec_nr_in_flight(cwq, work_color); 17441da177e4SLinus Torvalds } 1745a62428c0STejun Heo 1746affee4b2STejun Heo /** 1747affee4b2STejun Heo * process_scheduled_works - process scheduled works 1748affee4b2STejun Heo * @worker: self 1749affee4b2STejun Heo * 1750affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 1751affee4b2STejun Heo * may change while processing a work, so this function repeatedly 1752affee4b2STejun Heo * fetches a work from the top and executes it. 1753affee4b2STejun Heo * 1754affee4b2STejun Heo * CONTEXT: 17558b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1756affee4b2STejun Heo * multiple times. 1757affee4b2STejun Heo */ 1758affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 1759a62428c0STejun Heo { 1760affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 1761affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 1762a62428c0STejun Heo struct work_struct, entry); 1763c34056a3STejun Heo process_one_work(worker, work); 1764a62428c0STejun Heo } 17651da177e4SLinus Torvalds } 17661da177e4SLinus Torvalds 17674690c4abSTejun Heo /** 17684690c4abSTejun Heo * worker_thread - the worker thread function 1769c34056a3STejun Heo * @__worker: self 17704690c4abSTejun Heo * 1771e22bee78STejun Heo * The gcwq worker thread function. There's a single dynamic pool of 1772e22bee78STejun Heo * these per each cpu. These workers process all works regardless of 1773e22bee78STejun Heo * their specific target workqueue. The only exception is works which 1774e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 1775e22bee78STejun Heo * rescuer_thread(). 17764690c4abSTejun Heo */ 1777c34056a3STejun Heo static int worker_thread(void *__worker) 17781da177e4SLinus Torvalds { 1779c34056a3STejun Heo struct worker *worker = __worker; 17808b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 17811da177e4SLinus Torvalds 1782e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 1783e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 1784c8e55f36STejun Heo woke_up: 17858b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1786affee4b2STejun Heo 1787c8e55f36STejun Heo /* DIE can be set only while we're idle, checking here is enough */ 1788c8e55f36STejun Heo if (worker->flags & WORKER_DIE) { 1789c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1790e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 1791c8e55f36STejun Heo return 0; 1792c8e55f36STejun Heo } 1793c8e55f36STejun Heo 1794c8e55f36STejun Heo worker_leave_idle(worker); 1795db7bccf4STejun Heo recheck: 1796e22bee78STejun Heo /* no more worker necessary? */ 1797e22bee78STejun Heo if (!need_more_worker(gcwq)) 1798e22bee78STejun Heo goto sleep; 1799e22bee78STejun Heo 1800e22bee78STejun Heo /* do we need to manage? */ 1801e22bee78STejun Heo if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) 1802e22bee78STejun Heo goto recheck; 1803e22bee78STejun Heo 1804c8e55f36STejun Heo /* 1805c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 1806c8e55f36STejun Heo * preparing to process a work or actually processing it. 1807c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 1808c8e55f36STejun Heo */ 1809c8e55f36STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1810c8e55f36STejun Heo 1811e22bee78STejun Heo /* 1812e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 1813e22bee78STejun Heo * at least one idle worker or that someone else has already 1814e22bee78STejun Heo * assumed the manager role. 1815e22bee78STejun Heo */ 1816e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 1817e22bee78STejun Heo 1818e22bee78STejun Heo do { 1819affee4b2STejun Heo struct work_struct *work = 18207e11629dSTejun Heo list_first_entry(&gcwq->worklist, 1821affee4b2STejun Heo struct work_struct, entry); 1822affee4b2STejun Heo 1823c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 1824affee4b2STejun Heo /* optimization path, not strictly necessary */ 1825affee4b2STejun Heo process_one_work(worker, work); 1826affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 1827affee4b2STejun Heo process_scheduled_works(worker); 1828affee4b2STejun Heo } else { 1829c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 1830affee4b2STejun Heo process_scheduled_works(worker); 1831affee4b2STejun Heo } 1832e22bee78STejun Heo } while (keep_working(gcwq)); 1833affee4b2STejun Heo 1834e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 1835d313dd85STejun Heo sleep: 1836e22bee78STejun Heo if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) 1837e22bee78STejun Heo goto recheck; 1838d313dd85STejun Heo 1839c8e55f36STejun Heo /* 1840e22bee78STejun Heo * gcwq->lock is held and there's no work to process and no 1841e22bee78STejun Heo * need to manage, sleep. Workers are woken up only while 1842e22bee78STejun Heo * holding gcwq->lock or from local cpu, so setting the 1843e22bee78STejun Heo * current state before releasing gcwq->lock is enough to 1844e22bee78STejun Heo * prevent losing any event. 1845c8e55f36STejun Heo */ 1846c8e55f36STejun Heo worker_enter_idle(worker); 1847c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 18488b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1849c8e55f36STejun Heo schedule(); 1850c8e55f36STejun Heo goto woke_up; 18511da177e4SLinus Torvalds } 18521da177e4SLinus Torvalds 1853e22bee78STejun Heo /** 1854e22bee78STejun Heo * rescuer_thread - the rescuer thread function 1855e22bee78STejun Heo * @__wq: the associated workqueue 1856e22bee78STejun Heo * 1857e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 1858e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 1859e22bee78STejun Heo * 1860e22bee78STejun Heo * Regular work processing on a gcwq may block trying to create a new 1861e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 1862e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 1863e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 1864e22bee78STejun Heo * the problem rescuer solves. 1865e22bee78STejun Heo * 1866e22bee78STejun Heo * When such condition is possible, the gcwq summons rescuers of all 1867e22bee78STejun Heo * workqueues which have works queued on the gcwq and let them process 1868e22bee78STejun Heo * those works so that forward progress can be guaranteed. 1869e22bee78STejun Heo * 1870e22bee78STejun Heo * This should happen rarely. 1871e22bee78STejun Heo */ 1872e22bee78STejun Heo static int rescuer_thread(void *__wq) 1873e22bee78STejun Heo { 1874e22bee78STejun Heo struct workqueue_struct *wq = __wq; 1875e22bee78STejun Heo struct worker *rescuer = wq->rescuer; 1876e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 1877e22bee78STejun Heo unsigned int cpu; 1878e22bee78STejun Heo 1879e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 1880e22bee78STejun Heo repeat: 1881e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 1882e22bee78STejun Heo 1883e22bee78STejun Heo if (kthread_should_stop()) 1884e22bee78STejun Heo return 0; 1885e22bee78STejun Heo 1886e22bee78STejun Heo for_each_cpu(cpu, wq->mayday_mask) { 1887e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 1888e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 1889e22bee78STejun Heo struct work_struct *work, *n; 1890e22bee78STejun Heo 1891e22bee78STejun Heo __set_current_state(TASK_RUNNING); 1892e22bee78STejun Heo cpumask_clear_cpu(cpu, wq->mayday_mask); 1893e22bee78STejun Heo 1894e22bee78STejun Heo /* migrate to the target cpu if possible */ 1895e22bee78STejun Heo rescuer->gcwq = gcwq; 1896e22bee78STejun Heo worker_maybe_bind_and_lock(rescuer); 1897e22bee78STejun Heo 1898e22bee78STejun Heo /* 1899e22bee78STejun Heo * Slurp in all works issued via this workqueue and 1900e22bee78STejun Heo * process'em. 1901e22bee78STejun Heo */ 1902e22bee78STejun Heo BUG_ON(!list_empty(&rescuer->scheduled)); 1903e22bee78STejun Heo list_for_each_entry_safe(work, n, &gcwq->worklist, entry) 1904e22bee78STejun Heo if (get_work_cwq(work) == cwq) 1905e22bee78STejun Heo move_linked_works(work, scheduled, &n); 1906e22bee78STejun Heo 1907e22bee78STejun Heo process_scheduled_works(rescuer); 1908e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1909e22bee78STejun Heo } 1910e22bee78STejun Heo 1911e22bee78STejun Heo schedule(); 1912e22bee78STejun Heo goto repeat; 1913e22bee78STejun Heo } 1914e22bee78STejun Heo 1915fc2e4d70SOleg Nesterov struct wq_barrier { 1916fc2e4d70SOleg Nesterov struct work_struct work; 1917fc2e4d70SOleg Nesterov struct completion done; 1918fc2e4d70SOleg Nesterov }; 1919fc2e4d70SOleg Nesterov 1920fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 1921fc2e4d70SOleg Nesterov { 1922fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 1923fc2e4d70SOleg Nesterov complete(&barr->done); 1924fc2e4d70SOleg Nesterov } 1925fc2e4d70SOleg Nesterov 19264690c4abSTejun Heo /** 19274690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 19284690c4abSTejun Heo * @cwq: cwq to insert barrier into 19294690c4abSTejun Heo * @barr: wq_barrier to insert 1930affee4b2STejun Heo * @target: target work to attach @barr to 1931affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 19324690c4abSTejun Heo * 1933affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 1934affee4b2STejun Heo * @target finishes execution. Please note that the ordering 1935affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 1936affee4b2STejun Heo * cpu. 1937affee4b2STejun Heo * 1938affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 1939affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 1940affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 1941affee4b2STejun Heo * flag of the previous work while there must be a valid next work 1942affee4b2STejun Heo * after a work with LINKED flag set. 1943affee4b2STejun Heo * 1944affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 1945affee4b2STejun Heo * underneath us, so we can't reliably determine cwq from @target. 19464690c4abSTejun Heo * 19474690c4abSTejun Heo * CONTEXT: 19488b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 19494690c4abSTejun Heo */ 195083c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 1951affee4b2STejun Heo struct wq_barrier *barr, 1952affee4b2STejun Heo struct work_struct *target, struct worker *worker) 1953fc2e4d70SOleg Nesterov { 1954affee4b2STejun Heo struct list_head *head; 1955affee4b2STejun Heo unsigned int linked = 0; 1956affee4b2STejun Heo 1957dc186ad7SThomas Gleixner /* 19588b03ae3cSTejun Heo * debugobject calls are safe here even with gcwq->lock locked 1959dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 1960dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 1961dc186ad7SThomas Gleixner * might deadlock. 1962dc186ad7SThomas Gleixner */ 1963dc186ad7SThomas Gleixner INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); 196422df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 1965fc2e4d70SOleg Nesterov init_completion(&barr->done); 196683c22520SOleg Nesterov 1967affee4b2STejun Heo /* 1968affee4b2STejun Heo * If @target is currently being executed, schedule the 1969affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 1970affee4b2STejun Heo */ 1971affee4b2STejun Heo if (worker) 1972affee4b2STejun Heo head = worker->scheduled.next; 1973affee4b2STejun Heo else { 1974affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 1975affee4b2STejun Heo 1976affee4b2STejun Heo head = target->entry.next; 1977affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 1978affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 1979affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 1980affee4b2STejun Heo } 1981affee4b2STejun Heo 1982dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 1983affee4b2STejun Heo insert_work(cwq, &barr->work, head, 1984affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 1985fc2e4d70SOleg Nesterov } 1986fc2e4d70SOleg Nesterov 198773f53c4aSTejun Heo /** 198873f53c4aSTejun Heo * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing 198973f53c4aSTejun Heo * @wq: workqueue being flushed 199073f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 199173f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 199273f53c4aSTejun Heo * 199373f53c4aSTejun Heo * Prepare cwqs for workqueue flushing. 199473f53c4aSTejun Heo * 199573f53c4aSTejun Heo * If @flush_color is non-negative, flush_color on all cwqs should be 199673f53c4aSTejun Heo * -1. If no cwq has in-flight commands at the specified color, all 199773f53c4aSTejun Heo * cwq->flush_color's stay at -1 and %false is returned. If any cwq 199873f53c4aSTejun Heo * has in flight commands, its cwq->flush_color is set to 199973f53c4aSTejun Heo * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq 200073f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 200173f53c4aSTejun Heo * 200273f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 200373f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 200473f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 200573f53c4aSTejun Heo * is returned. 200673f53c4aSTejun Heo * 200773f53c4aSTejun Heo * If @work_color is non-negative, all cwqs should have the same 200873f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 200973f53c4aSTejun Heo * advanced to @work_color. 201073f53c4aSTejun Heo * 201173f53c4aSTejun Heo * CONTEXT: 201273f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 201373f53c4aSTejun Heo * 201473f53c4aSTejun Heo * RETURNS: 201573f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 201673f53c4aSTejun Heo * otherwise. 201773f53c4aSTejun Heo */ 201873f53c4aSTejun Heo static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, 201973f53c4aSTejun Heo int flush_color, int work_color) 20201da177e4SLinus Torvalds { 202173f53c4aSTejun Heo bool wait = false; 202273f53c4aSTejun Heo unsigned int cpu; 20231da177e4SLinus Torvalds 202473f53c4aSTejun Heo if (flush_color >= 0) { 202573f53c4aSTejun Heo BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); 202673f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 1); 202773f53c4aSTejun Heo } 202873f53c4aSTejun Heo 202973f53c4aSTejun Heo for_each_possible_cpu(cpu) { 203073f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 20318b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 20322355b70fSLai Jiangshan 20338b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 203473f53c4aSTejun Heo 203573f53c4aSTejun Heo if (flush_color >= 0) { 203673f53c4aSTejun Heo BUG_ON(cwq->flush_color != -1); 203773f53c4aSTejun Heo 203873f53c4aSTejun Heo if (cwq->nr_in_flight[flush_color]) { 203973f53c4aSTejun Heo cwq->flush_color = flush_color; 204073f53c4aSTejun Heo atomic_inc(&wq->nr_cwqs_to_flush); 204173f53c4aSTejun Heo wait = true; 204283c22520SOleg Nesterov } 204373f53c4aSTejun Heo } 204473f53c4aSTejun Heo 204573f53c4aSTejun Heo if (work_color >= 0) { 204673f53c4aSTejun Heo BUG_ON(work_color != work_next_color(cwq->work_color)); 204773f53c4aSTejun Heo cwq->work_color = work_color; 204873f53c4aSTejun Heo } 204973f53c4aSTejun Heo 20508b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 2051dc186ad7SThomas Gleixner } 205214441960SOleg Nesterov 205373f53c4aSTejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) 205473f53c4aSTejun Heo complete(&wq->first_flusher->done); 205573f53c4aSTejun Heo 205673f53c4aSTejun Heo return wait; 205783c22520SOleg Nesterov } 20581da177e4SLinus Torvalds 20590fcb78c2SRolf Eike Beer /** 20601da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 20610fcb78c2SRolf Eike Beer * @wq: workqueue to flush 20621da177e4SLinus Torvalds * 20631da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 20641da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 20651da177e4SLinus Torvalds * 2066fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2067fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 20681da177e4SLinus Torvalds */ 20697ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 20701da177e4SLinus Torvalds { 207173f53c4aSTejun Heo struct wq_flusher this_flusher = { 207273f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 207373f53c4aSTejun Heo .flush_color = -1, 207473f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 207573f53c4aSTejun Heo }; 207673f53c4aSTejun Heo int next_color; 2077b1f4ec17SOleg Nesterov 20783295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 20793295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 208073f53c4aSTejun Heo 208173f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 208273f53c4aSTejun Heo 208373f53c4aSTejun Heo /* 208473f53c4aSTejun Heo * Start-to-wait phase 208573f53c4aSTejun Heo */ 208673f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 208773f53c4aSTejun Heo 208873f53c4aSTejun Heo if (next_color != wq->flush_color) { 208973f53c4aSTejun Heo /* 209073f53c4aSTejun Heo * Color space is not full. The current work_color 209173f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 209273f53c4aSTejun Heo * by one. 209373f53c4aSTejun Heo */ 209473f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow)); 209573f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 209673f53c4aSTejun Heo wq->work_color = next_color; 209773f53c4aSTejun Heo 209873f53c4aSTejun Heo if (!wq->first_flusher) { 209973f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 210073f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 210173f53c4aSTejun Heo 210273f53c4aSTejun Heo wq->first_flusher = &this_flusher; 210373f53c4aSTejun Heo 210473f53c4aSTejun Heo if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, 210573f53c4aSTejun Heo wq->work_color)) { 210673f53c4aSTejun Heo /* nothing to flush, done */ 210773f53c4aSTejun Heo wq->flush_color = next_color; 210873f53c4aSTejun Heo wq->first_flusher = NULL; 210973f53c4aSTejun Heo goto out_unlock; 211073f53c4aSTejun Heo } 211173f53c4aSTejun Heo } else { 211273f53c4aSTejun Heo /* wait in queue */ 211373f53c4aSTejun Heo BUG_ON(wq->flush_color == this_flusher.flush_color); 211473f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 211573f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 211673f53c4aSTejun Heo } 211773f53c4aSTejun Heo } else { 211873f53c4aSTejun Heo /* 211973f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 212073f53c4aSTejun Heo * The next flush completion will assign us 212173f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 212273f53c4aSTejun Heo */ 212373f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 212473f53c4aSTejun Heo } 212573f53c4aSTejun Heo 212673f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 212773f53c4aSTejun Heo 212873f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 212973f53c4aSTejun Heo 213073f53c4aSTejun Heo /* 213173f53c4aSTejun Heo * Wake-up-and-cascade phase 213273f53c4aSTejun Heo * 213373f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 213473f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 213573f53c4aSTejun Heo */ 213673f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 213773f53c4aSTejun Heo return; 213873f53c4aSTejun Heo 213973f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 214073f53c4aSTejun Heo 21414ce48b37STejun Heo /* we might have raced, check again with mutex held */ 21424ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 21434ce48b37STejun Heo goto out_unlock; 21444ce48b37STejun Heo 214573f53c4aSTejun Heo wq->first_flusher = NULL; 214673f53c4aSTejun Heo 214773f53c4aSTejun Heo BUG_ON(!list_empty(&this_flusher.list)); 214873f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 214973f53c4aSTejun Heo 215073f53c4aSTejun Heo while (true) { 215173f53c4aSTejun Heo struct wq_flusher *next, *tmp; 215273f53c4aSTejun Heo 215373f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 215473f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 215573f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 215673f53c4aSTejun Heo break; 215773f53c4aSTejun Heo list_del_init(&next->list); 215873f53c4aSTejun Heo complete(&next->done); 215973f53c4aSTejun Heo } 216073f53c4aSTejun Heo 216173f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow) && 216273f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 216373f53c4aSTejun Heo 216473f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 216573f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 216673f53c4aSTejun Heo 216773f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 216873f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 216973f53c4aSTejun Heo /* 217073f53c4aSTejun Heo * Assign the same color to all overflowed 217173f53c4aSTejun Heo * flushers, advance work_color and append to 217273f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 217373f53c4aSTejun Heo * phase for these overflowed flushers. 217473f53c4aSTejun Heo */ 217573f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 217673f53c4aSTejun Heo tmp->flush_color = wq->work_color; 217773f53c4aSTejun Heo 217873f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 217973f53c4aSTejun Heo 218073f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 218173f53c4aSTejun Heo &wq->flusher_queue); 218273f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 218373f53c4aSTejun Heo } 218473f53c4aSTejun Heo 218573f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 218673f53c4aSTejun Heo BUG_ON(wq->flush_color != wq->work_color); 218773f53c4aSTejun Heo break; 218873f53c4aSTejun Heo } 218973f53c4aSTejun Heo 219073f53c4aSTejun Heo /* 219173f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 219273f53c4aSTejun Heo * the new first flusher and arm cwqs. 219373f53c4aSTejun Heo */ 219473f53c4aSTejun Heo BUG_ON(wq->flush_color == wq->work_color); 219573f53c4aSTejun Heo BUG_ON(wq->flush_color != next->flush_color); 219673f53c4aSTejun Heo 219773f53c4aSTejun Heo list_del_init(&next->list); 219873f53c4aSTejun Heo wq->first_flusher = next; 219973f53c4aSTejun Heo 220073f53c4aSTejun Heo if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) 220173f53c4aSTejun Heo break; 220273f53c4aSTejun Heo 220373f53c4aSTejun Heo /* 220473f53c4aSTejun Heo * Meh... this color is already done, clear first 220573f53c4aSTejun Heo * flusher and repeat cascading. 220673f53c4aSTejun Heo */ 220773f53c4aSTejun Heo wq->first_flusher = NULL; 220873f53c4aSTejun Heo } 220973f53c4aSTejun Heo 221073f53c4aSTejun Heo out_unlock: 221173f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 22121da177e4SLinus Torvalds } 2213ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 22141da177e4SLinus Torvalds 2215db700897SOleg Nesterov /** 2216db700897SOleg Nesterov * flush_work - block until a work_struct's callback has terminated 2217db700897SOleg Nesterov * @work: the work which is to be flushed 2218db700897SOleg Nesterov * 2219a67da70dSOleg Nesterov * Returns false if @work has already terminated. 2220a67da70dSOleg Nesterov * 2221db700897SOleg Nesterov * It is expected that, prior to calling flush_work(), the caller has 2222db700897SOleg Nesterov * arranged for the work to not be requeued, otherwise it doesn't make 2223db700897SOleg Nesterov * sense to use this function. 2224db700897SOleg Nesterov */ 2225db700897SOleg Nesterov int flush_work(struct work_struct *work) 2226db700897SOleg Nesterov { 2227affee4b2STejun Heo struct worker *worker = NULL; 22288b03ae3cSTejun Heo struct global_cwq *gcwq; 22297a22ad75STejun Heo struct cpu_workqueue_struct *cwq; 2230db700897SOleg Nesterov struct wq_barrier barr; 2231db700897SOleg Nesterov 2232db700897SOleg Nesterov might_sleep(); 22337a22ad75STejun Heo gcwq = get_work_gcwq(work); 22347a22ad75STejun Heo if (!gcwq) 2235db700897SOleg Nesterov return 0; 2236a67da70dSOleg Nesterov 22378b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2238db700897SOleg Nesterov if (!list_empty(&work->entry)) { 2239db700897SOleg Nesterov /* 2240db700897SOleg Nesterov * See the comment near try_to_grab_pending()->smp_rmb(). 22417a22ad75STejun Heo * If it was re-queued to a different gcwq under us, we 22427a22ad75STejun Heo * are not going to wait. 2243db700897SOleg Nesterov */ 2244db700897SOleg Nesterov smp_rmb(); 22457a22ad75STejun Heo cwq = get_work_cwq(work); 22467a22ad75STejun Heo if (unlikely(!cwq || gcwq != cwq->gcwq)) 22474690c4abSTejun Heo goto already_gone; 2248db700897SOleg Nesterov } else { 22497a22ad75STejun Heo worker = find_worker_executing_work(gcwq, work); 2250affee4b2STejun Heo if (!worker) 22514690c4abSTejun Heo goto already_gone; 22527a22ad75STejun Heo cwq = worker->current_cwq; 2253db700897SOleg Nesterov } 2254db700897SOleg Nesterov 2255affee4b2STejun Heo insert_wq_barrier(cwq, &barr, work, worker); 22568b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 22577a22ad75STejun Heo 22587a22ad75STejun Heo lock_map_acquire(&cwq->wq->lockdep_map); 22597a22ad75STejun Heo lock_map_release(&cwq->wq->lockdep_map); 22607a22ad75STejun Heo 2261db700897SOleg Nesterov wait_for_completion(&barr.done); 2262dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2263db700897SOleg Nesterov return 1; 22644690c4abSTejun Heo already_gone: 22658b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 22664690c4abSTejun Heo return 0; 2267db700897SOleg Nesterov } 2268db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2269db700897SOleg Nesterov 22706e84d644SOleg Nesterov /* 22711f1f642eSOleg Nesterov * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, 22726e84d644SOleg Nesterov * so this work can't be re-armed in any way. 22736e84d644SOleg Nesterov */ 22746e84d644SOleg Nesterov static int try_to_grab_pending(struct work_struct *work) 22756e84d644SOleg Nesterov { 22768b03ae3cSTejun Heo struct global_cwq *gcwq; 22771f1f642eSOleg Nesterov int ret = -1; 22786e84d644SOleg Nesterov 227922df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 22801f1f642eSOleg Nesterov return 0; 22816e84d644SOleg Nesterov 22826e84d644SOleg Nesterov /* 22836e84d644SOleg Nesterov * The queueing is in progress, or it is already queued. Try to 22846e84d644SOleg Nesterov * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 22856e84d644SOleg Nesterov */ 22867a22ad75STejun Heo gcwq = get_work_gcwq(work); 22877a22ad75STejun Heo if (!gcwq) 22886e84d644SOleg Nesterov return ret; 22896e84d644SOleg Nesterov 22908b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 22916e84d644SOleg Nesterov if (!list_empty(&work->entry)) { 22926e84d644SOleg Nesterov /* 22937a22ad75STejun Heo * This work is queued, but perhaps we locked the wrong gcwq. 22946e84d644SOleg Nesterov * In that case we must see the new value after rmb(), see 22956e84d644SOleg Nesterov * insert_work()->wmb(). 22966e84d644SOleg Nesterov */ 22976e84d644SOleg Nesterov smp_rmb(); 22987a22ad75STejun Heo if (gcwq == get_work_gcwq(work)) { 2299dc186ad7SThomas Gleixner debug_work_deactivate(work); 23006e84d644SOleg Nesterov list_del_init(&work->entry); 23017a22ad75STejun Heo cwq_dec_nr_in_flight(get_work_cwq(work), 23027a22ad75STejun Heo get_work_color(work)); 23036e84d644SOleg Nesterov ret = 1; 23046e84d644SOleg Nesterov } 23056e84d644SOleg Nesterov } 23068b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23076e84d644SOleg Nesterov 23086e84d644SOleg Nesterov return ret; 23096e84d644SOleg Nesterov } 23106e84d644SOleg Nesterov 23117a22ad75STejun Heo static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) 2312b89deed3SOleg Nesterov { 2313b89deed3SOleg Nesterov struct wq_barrier barr; 2314affee4b2STejun Heo struct worker *worker; 2315b89deed3SOleg Nesterov 23168b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2317affee4b2STejun Heo 23187a22ad75STejun Heo worker = find_worker_executing_work(gcwq, work); 23197a22ad75STejun Heo if (unlikely(worker)) 23207a22ad75STejun Heo insert_wq_barrier(worker->current_cwq, &barr, work, worker); 2321affee4b2STejun Heo 23228b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 2323b89deed3SOleg Nesterov 2324affee4b2STejun Heo if (unlikely(worker)) { 2325b89deed3SOleg Nesterov wait_for_completion(&barr.done); 2326dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2327dc186ad7SThomas Gleixner } 2328b89deed3SOleg Nesterov } 2329b89deed3SOleg Nesterov 23306e84d644SOleg Nesterov static void wait_on_work(struct work_struct *work) 2331b89deed3SOleg Nesterov { 2332b1f4ec17SOleg Nesterov int cpu; 2333b89deed3SOleg Nesterov 2334f293ea92SOleg Nesterov might_sleep(); 2335f293ea92SOleg Nesterov 23363295f0efSIngo Molnar lock_map_acquire(&work->lockdep_map); 23373295f0efSIngo Molnar lock_map_release(&work->lockdep_map); 23384e6045f1SJohannes Berg 23391537663fSTejun Heo for_each_possible_cpu(cpu) 23407a22ad75STejun Heo wait_on_cpu_work(get_gcwq(cpu), work); 23416e84d644SOleg Nesterov } 23426e84d644SOleg Nesterov 23431f1f642eSOleg Nesterov static int __cancel_work_timer(struct work_struct *work, 23441f1f642eSOleg Nesterov struct timer_list* timer) 23451f1f642eSOleg Nesterov { 23461f1f642eSOleg Nesterov int ret; 23471f1f642eSOleg Nesterov 23481f1f642eSOleg Nesterov do { 23491f1f642eSOleg Nesterov ret = (timer && likely(del_timer(timer))); 23501f1f642eSOleg Nesterov if (!ret) 23511f1f642eSOleg Nesterov ret = try_to_grab_pending(work); 23521f1f642eSOleg Nesterov wait_on_work(work); 23531f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 23541f1f642eSOleg Nesterov 23557a22ad75STejun Heo clear_work_data(work); 23561f1f642eSOleg Nesterov return ret; 23571f1f642eSOleg Nesterov } 23581f1f642eSOleg Nesterov 23596e84d644SOleg Nesterov /** 23606e84d644SOleg Nesterov * cancel_work_sync - block until a work_struct's callback has terminated 23616e84d644SOleg Nesterov * @work: the work which is to be flushed 23626e84d644SOleg Nesterov * 23631f1f642eSOleg Nesterov * Returns true if @work was pending. 23641f1f642eSOleg Nesterov * 23656e84d644SOleg Nesterov * cancel_work_sync() will cancel the work if it is queued. If the work's 23666e84d644SOleg Nesterov * callback appears to be running, cancel_work_sync() will block until it 23676e84d644SOleg Nesterov * has completed. 23686e84d644SOleg Nesterov * 23696e84d644SOleg Nesterov * It is possible to use this function if the work re-queues itself. It can 23706e84d644SOleg Nesterov * cancel the work even if it migrates to another workqueue, however in that 23716e84d644SOleg Nesterov * case it only guarantees that work->func() has completed on the last queued 23726e84d644SOleg Nesterov * workqueue. 23736e84d644SOleg Nesterov * 23746e84d644SOleg Nesterov * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not 23756e84d644SOleg Nesterov * pending, otherwise it goes into a busy-wait loop until the timer expires. 23766e84d644SOleg Nesterov * 23776e84d644SOleg Nesterov * The caller must ensure that workqueue_struct on which this work was last 23786e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 23796e84d644SOleg Nesterov */ 23801f1f642eSOleg Nesterov int cancel_work_sync(struct work_struct *work) 23816e84d644SOleg Nesterov { 23821f1f642eSOleg Nesterov return __cancel_work_timer(work, NULL); 2383b89deed3SOleg Nesterov } 238428e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2385b89deed3SOleg Nesterov 23866e84d644SOleg Nesterov /** 2387f5a421a4SOleg Nesterov * cancel_delayed_work_sync - reliably kill off a delayed work. 23886e84d644SOleg Nesterov * @dwork: the delayed work struct 23896e84d644SOleg Nesterov * 23901f1f642eSOleg Nesterov * Returns true if @dwork was pending. 23911f1f642eSOleg Nesterov * 23926e84d644SOleg Nesterov * It is possible to use this function if @dwork rearms itself via queue_work() 23936e84d644SOleg Nesterov * or queue_delayed_work(). See also the comment for cancel_work_sync(). 23946e84d644SOleg Nesterov */ 23951f1f642eSOleg Nesterov int cancel_delayed_work_sync(struct delayed_work *dwork) 23966e84d644SOleg Nesterov { 23971f1f642eSOleg Nesterov return __cancel_work_timer(&dwork->work, &dwork->timer); 23986e84d644SOleg Nesterov } 2399f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 24001da177e4SLinus Torvalds 24010fcb78c2SRolf Eike Beer /** 24020fcb78c2SRolf Eike Beer * schedule_work - put work task in global workqueue 24030fcb78c2SRolf Eike Beer * @work: job to be done 24040fcb78c2SRolf Eike Beer * 24055b0f437dSBart Van Assche * Returns zero if @work was already on the kernel-global workqueue and 24065b0f437dSBart Van Assche * non-zero otherwise. 24075b0f437dSBart Van Assche * 24085b0f437dSBart Van Assche * This puts a job in the kernel-global workqueue if it was not already 24095b0f437dSBart Van Assche * queued and leaves it in the same position on the kernel-global 24105b0f437dSBart Van Assche * workqueue otherwise. 24110fcb78c2SRolf Eike Beer */ 24127ad5b3a5SHarvey Harrison int schedule_work(struct work_struct *work) 24131da177e4SLinus Torvalds { 2414d320c038STejun Heo return queue_work(system_wq, work); 24151da177e4SLinus Torvalds } 2416ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_work); 24171da177e4SLinus Torvalds 2418c1a220e7SZhang Rui /* 2419c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2420c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2421c1a220e7SZhang Rui * @work: job to be done 2422c1a220e7SZhang Rui * 2423c1a220e7SZhang Rui * This puts a job on a specific cpu 2424c1a220e7SZhang Rui */ 2425c1a220e7SZhang Rui int schedule_work_on(int cpu, struct work_struct *work) 2426c1a220e7SZhang Rui { 2427d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 2428c1a220e7SZhang Rui } 2429c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 2430c1a220e7SZhang Rui 24310fcb78c2SRolf Eike Beer /** 24320fcb78c2SRolf Eike Beer * schedule_delayed_work - put work task in global workqueue after delay 243352bad64dSDavid Howells * @dwork: job to be done 243452bad64dSDavid Howells * @delay: number of jiffies to wait or 0 for immediate execution 24350fcb78c2SRolf Eike Beer * 24360fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 24370fcb78c2SRolf Eike Beer * workqueue. 24380fcb78c2SRolf Eike Beer */ 24397ad5b3a5SHarvey Harrison int schedule_delayed_work(struct delayed_work *dwork, 244082f67cd9SIngo Molnar unsigned long delay) 24411da177e4SLinus Torvalds { 2442d320c038STejun Heo return queue_delayed_work(system_wq, dwork, delay); 24431da177e4SLinus Torvalds } 2444ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work); 24451da177e4SLinus Torvalds 24460fcb78c2SRolf Eike Beer /** 24478c53e463SLinus Torvalds * flush_delayed_work - block until a dwork_struct's callback has terminated 24488c53e463SLinus Torvalds * @dwork: the delayed work which is to be flushed 24498c53e463SLinus Torvalds * 24508c53e463SLinus Torvalds * Any timeout is cancelled, and any pending work is run immediately. 24518c53e463SLinus Torvalds */ 24528c53e463SLinus Torvalds void flush_delayed_work(struct delayed_work *dwork) 24538c53e463SLinus Torvalds { 24548c53e463SLinus Torvalds if (del_timer_sync(&dwork->timer)) { 24557a22ad75STejun Heo __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq, 24564690c4abSTejun Heo &dwork->work); 24578c53e463SLinus Torvalds put_cpu(); 24588c53e463SLinus Torvalds } 24598c53e463SLinus Torvalds flush_work(&dwork->work); 24608c53e463SLinus Torvalds } 24618c53e463SLinus Torvalds EXPORT_SYMBOL(flush_delayed_work); 24628c53e463SLinus Torvalds 24638c53e463SLinus Torvalds /** 24640fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 24650fcb78c2SRolf Eike Beer * @cpu: cpu to use 246652bad64dSDavid Howells * @dwork: job to be done 24670fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 24680fcb78c2SRolf Eike Beer * 24690fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 24700fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 24710fcb78c2SRolf Eike Beer */ 24721da177e4SLinus Torvalds int schedule_delayed_work_on(int cpu, 247352bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 24741da177e4SLinus Torvalds { 2475d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 24761da177e4SLinus Torvalds } 2477ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 24781da177e4SLinus Torvalds 2479b6136773SAndrew Morton /** 2480b6136773SAndrew Morton * schedule_on_each_cpu - call a function on each online CPU from keventd 2481b6136773SAndrew Morton * @func: the function to call 2482b6136773SAndrew Morton * 2483b6136773SAndrew Morton * Returns zero on success. 2484b6136773SAndrew Morton * Returns -ve errno on failure. 2485b6136773SAndrew Morton * 2486b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 2487b6136773SAndrew Morton */ 248865f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 248915316ba8SChristoph Lameter { 249015316ba8SChristoph Lameter int cpu; 2491b6136773SAndrew Morton struct work_struct *works; 249215316ba8SChristoph Lameter 2493b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 2494b6136773SAndrew Morton if (!works) 249515316ba8SChristoph Lameter return -ENOMEM; 2496b6136773SAndrew Morton 249795402b38SGautham R Shenoy get_online_cpus(); 249893981800STejun Heo 249915316ba8SChristoph Lameter for_each_online_cpu(cpu) { 25009bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 25019bfb1839SIngo Molnar 25029bfb1839SIngo Molnar INIT_WORK(work, func); 25038de6d308SOleg Nesterov schedule_work_on(cpu, work); 250415316ba8SChristoph Lameter } 250593981800STejun Heo 250693981800STejun Heo for_each_online_cpu(cpu) 25078616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 250893981800STejun Heo 250995402b38SGautham R Shenoy put_online_cpus(); 2510b6136773SAndrew Morton free_percpu(works); 251115316ba8SChristoph Lameter return 0; 251215316ba8SChristoph Lameter } 251315316ba8SChristoph Lameter 2514eef6a7d5SAlan Stern /** 2515eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 2516eef6a7d5SAlan Stern * 2517eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 2518eef6a7d5SAlan Stern * completion. 2519eef6a7d5SAlan Stern * 2520eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 2521eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 2522eef6a7d5SAlan Stern * will lead to deadlock: 2523eef6a7d5SAlan Stern * 2524eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 2525eef6a7d5SAlan Stern * a lock held by your code or its caller. 2526eef6a7d5SAlan Stern * 2527eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 2528eef6a7d5SAlan Stern * 2529eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 2530eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 2531eef6a7d5SAlan Stern * what locks they need, which you have no control over. 2532eef6a7d5SAlan Stern * 2533eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 2534eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 2535eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 2536eef6a7d5SAlan Stern * cancel_work_sync() instead. 2537eef6a7d5SAlan Stern */ 25381da177e4SLinus Torvalds void flush_scheduled_work(void) 25391da177e4SLinus Torvalds { 2540d320c038STejun Heo flush_workqueue(system_wq); 25411da177e4SLinus Torvalds } 2542ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 25431da177e4SLinus Torvalds 25441da177e4SLinus Torvalds /** 25451fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 25461fa44ecaSJames Bottomley * @fn: the function to execute 25471fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 25481fa44ecaSJames Bottomley * be available when the work executes) 25491fa44ecaSJames Bottomley * 25501fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 25511fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 25521fa44ecaSJames Bottomley * 25531fa44ecaSJames Bottomley * Returns: 0 - function was executed 25541fa44ecaSJames Bottomley * 1 - function was scheduled for execution 25551fa44ecaSJames Bottomley */ 255665f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 25571fa44ecaSJames Bottomley { 25581fa44ecaSJames Bottomley if (!in_interrupt()) { 255965f27f38SDavid Howells fn(&ew->work); 25601fa44ecaSJames Bottomley return 0; 25611fa44ecaSJames Bottomley } 25621fa44ecaSJames Bottomley 256365f27f38SDavid Howells INIT_WORK(&ew->work, fn); 25641fa44ecaSJames Bottomley schedule_work(&ew->work); 25651fa44ecaSJames Bottomley 25661fa44ecaSJames Bottomley return 1; 25671fa44ecaSJames Bottomley } 25681fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 25691fa44ecaSJames Bottomley 25701da177e4SLinus Torvalds int keventd_up(void) 25711da177e4SLinus Torvalds { 2572d320c038STejun Heo return system_wq != NULL; 25731da177e4SLinus Torvalds } 25741da177e4SLinus Torvalds 25750f900049STejun Heo static struct cpu_workqueue_struct *alloc_cwqs(void) 25760f900049STejun Heo { 25770f900049STejun Heo /* 25780f900049STejun Heo * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. 25790f900049STejun Heo * Make sure that the alignment isn't lower than that of 25800f900049STejun Heo * unsigned long long. 25810f900049STejun Heo */ 25820f900049STejun Heo const size_t size = sizeof(struct cpu_workqueue_struct); 25830f900049STejun Heo const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, 25840f900049STejun Heo __alignof__(unsigned long long)); 25850f900049STejun Heo struct cpu_workqueue_struct *cwqs; 25860f900049STejun Heo #ifndef CONFIG_SMP 25870f900049STejun Heo void *ptr; 25880f900049STejun Heo 25890f900049STejun Heo /* 25900f900049STejun Heo * On UP, percpu allocator doesn't honor alignment parameter 25910f900049STejun Heo * and simply uses arch-dependent default. Allocate enough 25920f900049STejun Heo * room to align cwq and put an extra pointer at the end 25930f900049STejun Heo * pointing back to the originally allocated pointer which 25940f900049STejun Heo * will be used for free. 25950f900049STejun Heo * 25960f900049STejun Heo * FIXME: This really belongs to UP percpu code. Update UP 25970f900049STejun Heo * percpu code to honor alignment and remove this ugliness. 25980f900049STejun Heo */ 25990f900049STejun Heo ptr = __alloc_percpu(size + align + sizeof(void *), 1); 26000f900049STejun Heo cwqs = PTR_ALIGN(ptr, align); 26010f900049STejun Heo *(void **)per_cpu_ptr(cwqs + 1, 0) = ptr; 26020f900049STejun Heo #else 26030f900049STejun Heo /* On SMP, percpu allocator can do it itself */ 26040f900049STejun Heo cwqs = __alloc_percpu(size, align); 26050f900049STejun Heo #endif 26060f900049STejun Heo /* just in case, make sure it's actually aligned */ 26070f900049STejun Heo BUG_ON(!IS_ALIGNED((unsigned long)cwqs, align)); 26080f900049STejun Heo return cwqs; 26090f900049STejun Heo } 26100f900049STejun Heo 26110f900049STejun Heo static void free_cwqs(struct cpu_workqueue_struct *cwqs) 26120f900049STejun Heo { 26130f900049STejun Heo #ifndef CONFIG_SMP 26140f900049STejun Heo /* on UP, the pointer to free is stored right after the cwq */ 26150f900049STejun Heo if (cwqs) 26160f900049STejun Heo free_percpu(*(void **)per_cpu_ptr(cwqs + 1, 0)); 26170f900049STejun Heo #else 26180f900049STejun Heo free_percpu(cwqs); 26190f900049STejun Heo #endif 26200f900049STejun Heo } 26210f900049STejun Heo 2622b71ab8c2STejun Heo static int wq_clamp_max_active(int max_active, const char *name) 2623b71ab8c2STejun Heo { 2624b71ab8c2STejun Heo if (max_active < 1 || max_active > WQ_MAX_ACTIVE) 2625b71ab8c2STejun Heo printk(KERN_WARNING "workqueue: max_active %d requested for %s " 2626b71ab8c2STejun Heo "is out of range, clamping between %d and %d\n", 2627b71ab8c2STejun Heo max_active, name, 1, WQ_MAX_ACTIVE); 2628b71ab8c2STejun Heo 2629b71ab8c2STejun Heo return clamp_val(max_active, 1, WQ_MAX_ACTIVE); 2630b71ab8c2STejun Heo } 2631b71ab8c2STejun Heo 2632d320c038STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *name, 263397e37d7bSTejun Heo unsigned int flags, 26341e19ffc6STejun Heo int max_active, 2635eb13ba87SJohannes Berg struct lock_class_key *key, 2636eb13ba87SJohannes Berg const char *lock_name) 26373af24433SOleg Nesterov { 26383af24433SOleg Nesterov struct workqueue_struct *wq; 2639c34056a3STejun Heo unsigned int cpu; 26403af24433SOleg Nesterov 2641d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 2642b71ab8c2STejun Heo max_active = wq_clamp_max_active(max_active, name); 26431e19ffc6STejun Heo 26443af24433SOleg Nesterov wq = kzalloc(sizeof(*wq), GFP_KERNEL); 26453af24433SOleg Nesterov if (!wq) 26464690c4abSTejun Heo goto err; 26473af24433SOleg Nesterov 26480f900049STejun Heo wq->cpu_wq = alloc_cwqs(); 26494690c4abSTejun Heo if (!wq->cpu_wq) 26504690c4abSTejun Heo goto err; 26513af24433SOleg Nesterov 265297e37d7bSTejun Heo wq->flags = flags; 2653a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 265473f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 265573f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 0); 265673f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 265773f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 2658502ca9d8STejun Heo wq->single_cpu = NR_CPUS; 2659502ca9d8STejun Heo 26603af24433SOleg Nesterov wq->name = name; 2661eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 2662cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 26633af24433SOleg Nesterov 26643af24433SOleg Nesterov for_each_possible_cpu(cpu) { 26651537663fSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 26668b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 26671537663fSTejun Heo 26680f900049STejun Heo BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 26698b03ae3cSTejun Heo cwq->gcwq = gcwq; 2670c34056a3STejun Heo cwq->wq = wq; 267173f53c4aSTejun Heo cwq->flush_color = -1; 26721e19ffc6STejun Heo cwq->max_active = max_active; 26731e19ffc6STejun Heo INIT_LIST_HEAD(&cwq->delayed_works); 2674e22bee78STejun Heo } 26751537663fSTejun Heo 2676e22bee78STejun Heo if (flags & WQ_RESCUER) { 2677e22bee78STejun Heo struct worker *rescuer; 2678e22bee78STejun Heo 2679e22bee78STejun Heo if (!alloc_cpumask_var(&wq->mayday_mask, GFP_KERNEL)) 2680e22bee78STejun Heo goto err; 2681e22bee78STejun Heo 2682e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 2683e22bee78STejun Heo if (!rescuer) 2684e22bee78STejun Heo goto err; 2685e22bee78STejun Heo 2686e22bee78STejun Heo rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); 2687e22bee78STejun Heo if (IS_ERR(rescuer->task)) 2688e22bee78STejun Heo goto err; 2689e22bee78STejun Heo 2690e22bee78STejun Heo wq->rescuer = rescuer; 2691e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 2692e22bee78STejun Heo wake_up_process(rescuer->task); 26933af24433SOleg Nesterov } 26941537663fSTejun Heo 2695a0a1a5fdSTejun Heo /* 2696a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 2697a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 2698a0a1a5fdSTejun Heo * workqueue to workqueues list. 2699a0a1a5fdSTejun Heo */ 27001537663fSTejun Heo spin_lock(&workqueue_lock); 2701a0a1a5fdSTejun Heo 2702a0a1a5fdSTejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) 2703a0a1a5fdSTejun Heo for_each_possible_cpu(cpu) 2704a0a1a5fdSTejun Heo get_cwq(cpu, wq)->max_active = 0; 2705a0a1a5fdSTejun Heo 27061537663fSTejun Heo list_add(&wq->list, &workqueues); 2707a0a1a5fdSTejun Heo 27081537663fSTejun Heo spin_unlock(&workqueue_lock); 27091537663fSTejun Heo 27103af24433SOleg Nesterov return wq; 27114690c4abSTejun Heo err: 27124690c4abSTejun Heo if (wq) { 27130f900049STejun Heo free_cwqs(wq->cpu_wq); 2714e22bee78STejun Heo free_cpumask_var(wq->mayday_mask); 2715e22bee78STejun Heo kfree(wq->rescuer); 27164690c4abSTejun Heo kfree(wq); 27174690c4abSTejun Heo } 27184690c4abSTejun Heo return NULL; 27193af24433SOleg Nesterov } 2720d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 27213af24433SOleg Nesterov 27223af24433SOleg Nesterov /** 27233af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 27243af24433SOleg Nesterov * @wq: target workqueue 27253af24433SOleg Nesterov * 27263af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 27273af24433SOleg Nesterov */ 27283af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 27293af24433SOleg Nesterov { 2730c8e55f36STejun Heo unsigned int cpu; 27313af24433SOleg Nesterov 2732a0a1a5fdSTejun Heo flush_workqueue(wq); 2733a0a1a5fdSTejun Heo 2734a0a1a5fdSTejun Heo /* 2735a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 2736a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 2737a0a1a5fdSTejun Heo */ 273895402b38SGautham R Shenoy spin_lock(&workqueue_lock); 27393af24433SOleg Nesterov list_del(&wq->list); 274095402b38SGautham R Shenoy spin_unlock(&workqueue_lock); 27413af24433SOleg Nesterov 2742e22bee78STejun Heo /* sanity check */ 274373f53c4aSTejun Heo for_each_possible_cpu(cpu) { 274473f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 274573f53c4aSTejun Heo int i; 274673f53c4aSTejun Heo 274773f53c4aSTejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 274873f53c4aSTejun Heo BUG_ON(cwq->nr_in_flight[i]); 27491e19ffc6STejun Heo BUG_ON(cwq->nr_active); 27501e19ffc6STejun Heo BUG_ON(!list_empty(&cwq->delayed_works)); 275173f53c4aSTejun Heo } 27521537663fSTejun Heo 2753e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 2754e22bee78STejun Heo kthread_stop(wq->rescuer->task); 2755e22bee78STejun Heo free_cpumask_var(wq->mayday_mask); 2756e22bee78STejun Heo } 2757e22bee78STejun Heo 27580f900049STejun Heo free_cwqs(wq->cpu_wq); 27593af24433SOleg Nesterov kfree(wq); 27603af24433SOleg Nesterov } 27613af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 27623af24433SOleg Nesterov 2763dcd989cbSTejun Heo /** 2764dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 2765dcd989cbSTejun Heo * @wq: target workqueue 2766dcd989cbSTejun Heo * @max_active: new max_active value. 2767dcd989cbSTejun Heo * 2768dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 2769dcd989cbSTejun Heo * 2770dcd989cbSTejun Heo * CONTEXT: 2771dcd989cbSTejun Heo * Don't call from IRQ context. 2772dcd989cbSTejun Heo */ 2773dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 2774dcd989cbSTejun Heo { 2775dcd989cbSTejun Heo unsigned int cpu; 2776dcd989cbSTejun Heo 2777dcd989cbSTejun Heo max_active = wq_clamp_max_active(max_active, wq->name); 2778dcd989cbSTejun Heo 2779dcd989cbSTejun Heo spin_lock(&workqueue_lock); 2780dcd989cbSTejun Heo 2781dcd989cbSTejun Heo wq->saved_max_active = max_active; 2782dcd989cbSTejun Heo 2783dcd989cbSTejun Heo for_each_possible_cpu(cpu) { 2784dcd989cbSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 2785dcd989cbSTejun Heo 2786dcd989cbSTejun Heo spin_lock_irq(&gcwq->lock); 2787dcd989cbSTejun Heo 2788dcd989cbSTejun Heo if (!(wq->flags & WQ_FREEZEABLE) || 2789dcd989cbSTejun Heo !(gcwq->flags & GCWQ_FREEZING)) 2790dcd989cbSTejun Heo get_cwq(gcwq->cpu, wq)->max_active = max_active; 2791dcd989cbSTejun Heo 2792dcd989cbSTejun Heo spin_unlock_irq(&gcwq->lock); 2793dcd989cbSTejun Heo } 2794dcd989cbSTejun Heo 2795dcd989cbSTejun Heo spin_unlock(&workqueue_lock); 2796dcd989cbSTejun Heo } 2797dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 2798dcd989cbSTejun Heo 2799dcd989cbSTejun Heo /** 2800dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 2801dcd989cbSTejun Heo * @cpu: CPU in question 2802dcd989cbSTejun Heo * @wq: target workqueue 2803dcd989cbSTejun Heo * 2804dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 2805dcd989cbSTejun Heo * no synchronization around this function and the test result is 2806dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 2807dcd989cbSTejun Heo * 2808dcd989cbSTejun Heo * RETURNS: 2809dcd989cbSTejun Heo * %true if congested, %false otherwise. 2810dcd989cbSTejun Heo */ 2811dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 2812dcd989cbSTejun Heo { 2813dcd989cbSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2814dcd989cbSTejun Heo 2815dcd989cbSTejun Heo return !list_empty(&cwq->delayed_works); 2816dcd989cbSTejun Heo } 2817dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 2818dcd989cbSTejun Heo 2819dcd989cbSTejun Heo /** 2820dcd989cbSTejun Heo * work_cpu - return the last known associated cpu for @work 2821dcd989cbSTejun Heo * @work: the work of interest 2822dcd989cbSTejun Heo * 2823dcd989cbSTejun Heo * RETURNS: 2824dcd989cbSTejun Heo * CPU number if @work was ever queued. NR_CPUS otherwise. 2825dcd989cbSTejun Heo */ 2826dcd989cbSTejun Heo unsigned int work_cpu(struct work_struct *work) 2827dcd989cbSTejun Heo { 2828dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 2829dcd989cbSTejun Heo 2830dcd989cbSTejun Heo return gcwq ? gcwq->cpu : NR_CPUS; 2831dcd989cbSTejun Heo } 2832dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_cpu); 2833dcd989cbSTejun Heo 2834dcd989cbSTejun Heo /** 2835dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 2836dcd989cbSTejun Heo * @work: the work to be tested 2837dcd989cbSTejun Heo * 2838dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 2839dcd989cbSTejun Heo * synchronization around this function and the test result is 2840dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 2841dcd989cbSTejun Heo * Especially for reentrant wqs, the pending state might hide the 2842dcd989cbSTejun Heo * running state. 2843dcd989cbSTejun Heo * 2844dcd989cbSTejun Heo * RETURNS: 2845dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 2846dcd989cbSTejun Heo */ 2847dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 2848dcd989cbSTejun Heo { 2849dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 2850dcd989cbSTejun Heo unsigned long flags; 2851dcd989cbSTejun Heo unsigned int ret = 0; 2852dcd989cbSTejun Heo 2853dcd989cbSTejun Heo if (!gcwq) 2854dcd989cbSTejun Heo return false; 2855dcd989cbSTejun Heo 2856dcd989cbSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 2857dcd989cbSTejun Heo 2858dcd989cbSTejun Heo if (work_pending(work)) 2859dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 2860dcd989cbSTejun Heo if (find_worker_executing_work(gcwq, work)) 2861dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 2862dcd989cbSTejun Heo 2863dcd989cbSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 2864dcd989cbSTejun Heo 2865dcd989cbSTejun Heo return ret; 2866dcd989cbSTejun Heo } 2867dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 2868dcd989cbSTejun Heo 2869db7bccf4STejun Heo /* 2870db7bccf4STejun Heo * CPU hotplug. 2871db7bccf4STejun Heo * 2872e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 2873e22bee78STejun Heo * are a lot of assumptions on strong associations among work, cwq and 2874e22bee78STejun Heo * gcwq which make migrating pending and scheduled works very 2875e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 2876e22bee78STejun Heo * gcwqs serve mix of short, long and very long running works making 2877e22bee78STejun Heo * blocked draining impractical. 2878e22bee78STejun Heo * 2879e22bee78STejun Heo * This is solved by allowing a gcwq to be detached from CPU, running 2880e22bee78STejun Heo * it with unbound (rogue) workers and allowing it to be reattached 2881e22bee78STejun Heo * later if the cpu comes back online. A separate thread is created 2882e22bee78STejun Heo * to govern a gcwq in such state and is called the trustee of the 2883e22bee78STejun Heo * gcwq. 2884db7bccf4STejun Heo * 2885db7bccf4STejun Heo * Trustee states and their descriptions. 2886db7bccf4STejun Heo * 2887db7bccf4STejun Heo * START Command state used on startup. On CPU_DOWN_PREPARE, a 2888db7bccf4STejun Heo * new trustee is started with this state. 2889db7bccf4STejun Heo * 2890db7bccf4STejun Heo * IN_CHARGE Once started, trustee will enter this state after 2891e22bee78STejun Heo * assuming the manager role and making all existing 2892e22bee78STejun Heo * workers rogue. DOWN_PREPARE waits for trustee to 2893e22bee78STejun Heo * enter this state. After reaching IN_CHARGE, trustee 2894e22bee78STejun Heo * tries to execute the pending worklist until it's empty 2895e22bee78STejun Heo * and the state is set to BUTCHER, or the state is set 2896e22bee78STejun Heo * to RELEASE. 2897db7bccf4STejun Heo * 2898db7bccf4STejun Heo * BUTCHER Command state which is set by the cpu callback after 2899db7bccf4STejun Heo * the cpu has went down. Once this state is set trustee 2900db7bccf4STejun Heo * knows that there will be no new works on the worklist 2901db7bccf4STejun Heo * and once the worklist is empty it can proceed to 2902db7bccf4STejun Heo * killing idle workers. 2903db7bccf4STejun Heo * 2904db7bccf4STejun Heo * RELEASE Command state which is set by the cpu callback if the 2905db7bccf4STejun Heo * cpu down has been canceled or it has come online 2906db7bccf4STejun Heo * again. After recognizing this state, trustee stops 2907e22bee78STejun Heo * trying to drain or butcher and clears ROGUE, rebinds 2908e22bee78STejun Heo * all remaining workers back to the cpu and releases 2909e22bee78STejun Heo * manager role. 2910db7bccf4STejun Heo * 2911db7bccf4STejun Heo * DONE Trustee will enter this state after BUTCHER or RELEASE 2912db7bccf4STejun Heo * is complete. 2913db7bccf4STejun Heo * 2914db7bccf4STejun Heo * trustee CPU draining 2915db7bccf4STejun Heo * took over down complete 2916db7bccf4STejun Heo * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE 2917db7bccf4STejun Heo * | | ^ 2918db7bccf4STejun Heo * | CPU is back online v return workers | 2919db7bccf4STejun Heo * ----------------> RELEASE -------------- 2920db7bccf4STejun Heo */ 2921db7bccf4STejun Heo 2922db7bccf4STejun Heo /** 2923db7bccf4STejun Heo * trustee_wait_event_timeout - timed event wait for trustee 2924db7bccf4STejun Heo * @cond: condition to wait for 2925db7bccf4STejun Heo * @timeout: timeout in jiffies 2926db7bccf4STejun Heo * 2927db7bccf4STejun Heo * wait_event_timeout() for trustee to use. Handles locking and 2928db7bccf4STejun Heo * checks for RELEASE request. 2929db7bccf4STejun Heo * 2930db7bccf4STejun Heo * CONTEXT: 2931db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2932db7bccf4STejun Heo * multiple times. To be used by trustee. 2933db7bccf4STejun Heo * 2934db7bccf4STejun Heo * RETURNS: 2935db7bccf4STejun Heo * Positive indicating left time if @cond is satisfied, 0 if timed 2936db7bccf4STejun Heo * out, -1 if canceled. 2937db7bccf4STejun Heo */ 2938db7bccf4STejun Heo #define trustee_wait_event_timeout(cond, timeout) ({ \ 2939db7bccf4STejun Heo long __ret = (timeout); \ 2940db7bccf4STejun Heo while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ 2941db7bccf4STejun Heo __ret) { \ 2942db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); \ 2943db7bccf4STejun Heo __wait_event_timeout(gcwq->trustee_wait, (cond) || \ 2944db7bccf4STejun Heo (gcwq->trustee_state == TRUSTEE_RELEASE), \ 2945db7bccf4STejun Heo __ret); \ 2946db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); \ 2947db7bccf4STejun Heo } \ 2948db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ 2949db7bccf4STejun Heo }) 2950db7bccf4STejun Heo 2951db7bccf4STejun Heo /** 2952db7bccf4STejun Heo * trustee_wait_event - event wait for trustee 2953db7bccf4STejun Heo * @cond: condition to wait for 2954db7bccf4STejun Heo * 2955db7bccf4STejun Heo * wait_event() for trustee to use. Automatically handles locking and 2956db7bccf4STejun Heo * checks for CANCEL request. 2957db7bccf4STejun Heo * 2958db7bccf4STejun Heo * CONTEXT: 2959db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2960db7bccf4STejun Heo * multiple times. To be used by trustee. 2961db7bccf4STejun Heo * 2962db7bccf4STejun Heo * RETURNS: 2963db7bccf4STejun Heo * 0 if @cond is satisfied, -1 if canceled. 2964db7bccf4STejun Heo */ 2965db7bccf4STejun Heo #define trustee_wait_event(cond) ({ \ 2966db7bccf4STejun Heo long __ret1; \ 2967db7bccf4STejun Heo __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ 2968db7bccf4STejun Heo __ret1 < 0 ? -1 : 0; \ 2969db7bccf4STejun Heo }) 2970db7bccf4STejun Heo 2971db7bccf4STejun Heo static int __cpuinit trustee_thread(void *__gcwq) 2972db7bccf4STejun Heo { 2973db7bccf4STejun Heo struct global_cwq *gcwq = __gcwq; 2974db7bccf4STejun Heo struct worker *worker; 2975e22bee78STejun Heo struct work_struct *work; 2976db7bccf4STejun Heo struct hlist_node *pos; 2977e22bee78STejun Heo long rc; 2978db7bccf4STejun Heo int i; 2979db7bccf4STejun Heo 2980db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 2981db7bccf4STejun Heo 2982db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 2983db7bccf4STejun Heo /* 2984e22bee78STejun Heo * Claim the manager position and make all workers rogue. 2985e22bee78STejun Heo * Trustee must be bound to the target cpu and can't be 2986e22bee78STejun Heo * cancelled. 2987db7bccf4STejun Heo */ 2988db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 2989e22bee78STejun Heo rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); 2990e22bee78STejun Heo BUG_ON(rc < 0); 2991e22bee78STejun Heo 2992e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 2993db7bccf4STejun Heo 2994db7bccf4STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) 2995cb444766STejun Heo worker->flags |= WORKER_ROGUE; 2996db7bccf4STejun Heo 2997db7bccf4STejun Heo for_each_busy_worker(worker, i, pos, gcwq) 2998cb444766STejun Heo worker->flags |= WORKER_ROGUE; 2999db7bccf4STejun Heo 3000db7bccf4STejun Heo /* 3001e22bee78STejun Heo * Call schedule() so that we cross rq->lock and thus can 3002e22bee78STejun Heo * guarantee sched callbacks see the rogue flag. This is 3003e22bee78STejun Heo * necessary as scheduler callbacks may be invoked from other 3004e22bee78STejun Heo * cpus. 3005e22bee78STejun Heo */ 3006e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3007e22bee78STejun Heo schedule(); 3008e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3009e22bee78STejun Heo 3010e22bee78STejun Heo /* 3011cb444766STejun Heo * Sched callbacks are disabled now. Zap nr_running. After 3012cb444766STejun Heo * this, nr_running stays zero and need_more_worker() and 3013cb444766STejun Heo * keep_working() are always true as long as the worklist is 3014cb444766STejun Heo * not empty. 3015e22bee78STejun Heo */ 3016cb444766STejun Heo atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); 3017e22bee78STejun Heo 3018e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3019e22bee78STejun Heo del_timer_sync(&gcwq->idle_timer); 3020e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3021e22bee78STejun Heo 3022e22bee78STejun Heo /* 3023db7bccf4STejun Heo * We're now in charge. Notify and proceed to drain. We need 3024db7bccf4STejun Heo * to keep the gcwq running during the whole CPU down 3025db7bccf4STejun Heo * procedure as other cpu hotunplug callbacks may need to 3026db7bccf4STejun Heo * flush currently running tasks. 3027db7bccf4STejun Heo */ 3028db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_IN_CHARGE; 3029db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3030db7bccf4STejun Heo 3031db7bccf4STejun Heo /* 3032db7bccf4STejun Heo * The original cpu is in the process of dying and may go away 3033db7bccf4STejun Heo * anytime now. When that happens, we and all workers would 3034e22bee78STejun Heo * be migrated to other cpus. Try draining any left work. We 3035e22bee78STejun Heo * want to get it over with ASAP - spam rescuers, wake up as 3036e22bee78STejun Heo * many idlers as necessary and create new ones till the 3037e22bee78STejun Heo * worklist is empty. Note that if the gcwq is frozen, there 3038e22bee78STejun Heo * may be frozen works in freezeable cwqs. Don't declare 3039e22bee78STejun Heo * completion while frozen. 3040db7bccf4STejun Heo */ 3041db7bccf4STejun Heo while (gcwq->nr_workers != gcwq->nr_idle || 3042db7bccf4STejun Heo gcwq->flags & GCWQ_FREEZING || 3043db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_IN_CHARGE) { 3044e22bee78STejun Heo int nr_works = 0; 3045e22bee78STejun Heo 3046e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) { 3047e22bee78STejun Heo send_mayday(work); 3048e22bee78STejun Heo nr_works++; 3049e22bee78STejun Heo } 3050e22bee78STejun Heo 3051e22bee78STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) { 3052e22bee78STejun Heo if (!nr_works--) 3053e22bee78STejun Heo break; 3054e22bee78STejun Heo wake_up_process(worker->task); 3055e22bee78STejun Heo } 3056e22bee78STejun Heo 3057e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 3058e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3059e22bee78STejun Heo worker = create_worker(gcwq, false); 3060e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3061e22bee78STejun Heo if (worker) { 3062cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3063e22bee78STejun Heo start_worker(worker); 3064e22bee78STejun Heo } 3065e22bee78STejun Heo } 3066e22bee78STejun Heo 3067db7bccf4STejun Heo /* give a breather */ 3068db7bccf4STejun Heo if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) 3069db7bccf4STejun Heo break; 3070db7bccf4STejun Heo } 3071db7bccf4STejun Heo 3072e22bee78STejun Heo /* 3073e22bee78STejun Heo * Either all works have been scheduled and cpu is down, or 3074e22bee78STejun Heo * cpu down has already been canceled. Wait for and butcher 3075e22bee78STejun Heo * all workers till we're canceled. 3076e22bee78STejun Heo */ 3077e22bee78STejun Heo do { 3078e22bee78STejun Heo rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); 3079e22bee78STejun Heo while (!list_empty(&gcwq->idle_list)) 3080e22bee78STejun Heo destroy_worker(list_first_entry(&gcwq->idle_list, 3081e22bee78STejun Heo struct worker, entry)); 3082e22bee78STejun Heo } while (gcwq->nr_workers && rc >= 0); 3083e22bee78STejun Heo 3084e22bee78STejun Heo /* 3085e22bee78STejun Heo * At this point, either draining has completed and no worker 3086e22bee78STejun Heo * is left, or cpu down has been canceled or the cpu is being 3087e22bee78STejun Heo * brought back up. There shouldn't be any idle one left. 3088e22bee78STejun Heo * Tell the remaining busy ones to rebind once it finishes the 3089e22bee78STejun Heo * currently scheduled works by scheduling the rebind_work. 3090e22bee78STejun Heo */ 3091e22bee78STejun Heo WARN_ON(!list_empty(&gcwq->idle_list)); 3092e22bee78STejun Heo 3093e22bee78STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 3094e22bee78STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 3095e22bee78STejun Heo 3096e22bee78STejun Heo /* 3097e22bee78STejun Heo * Rebind_work may race with future cpu hotplug 3098e22bee78STejun Heo * operations. Use a separate flag to mark that 3099e22bee78STejun Heo * rebinding is scheduled. 3100e22bee78STejun Heo */ 3101cb444766STejun Heo worker->flags |= WORKER_REBIND; 3102cb444766STejun Heo worker->flags &= ~WORKER_ROGUE; 3103e22bee78STejun Heo 3104e22bee78STejun Heo /* queue rebind_work, wq doesn't matter, use the default one */ 3105e22bee78STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 3106e22bee78STejun Heo work_data_bits(rebind_work))) 3107e22bee78STejun Heo continue; 3108e22bee78STejun Heo 3109e22bee78STejun Heo debug_work_activate(rebind_work); 3110d320c038STejun Heo insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, 3111e22bee78STejun Heo worker->scheduled.next, 3112e22bee78STejun Heo work_color_to_flags(WORK_NO_COLOR)); 3113e22bee78STejun Heo } 3114e22bee78STejun Heo 3115e22bee78STejun Heo /* relinquish manager role */ 3116e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 3117e22bee78STejun Heo 3118db7bccf4STejun Heo /* notify completion */ 3119db7bccf4STejun Heo gcwq->trustee = NULL; 3120db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3121db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3122db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3123db7bccf4STejun Heo return 0; 3124db7bccf4STejun Heo } 3125db7bccf4STejun Heo 3126db7bccf4STejun Heo /** 3127db7bccf4STejun Heo * wait_trustee_state - wait for trustee to enter the specified state 3128db7bccf4STejun Heo * @gcwq: gcwq the trustee of interest belongs to 3129db7bccf4STejun Heo * @state: target state to wait for 3130db7bccf4STejun Heo * 3131db7bccf4STejun Heo * Wait for the trustee to reach @state. DONE is already matched. 3132db7bccf4STejun Heo * 3133db7bccf4STejun Heo * CONTEXT: 3134db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3135db7bccf4STejun Heo * multiple times. To be used by cpu_callback. 3136db7bccf4STejun Heo */ 3137db7bccf4STejun Heo static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) 3138db7bccf4STejun Heo { 3139db7bccf4STejun Heo if (!(gcwq->trustee_state == state || 3140db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE)) { 3141db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3142db7bccf4STejun Heo __wait_event(gcwq->trustee_wait, 3143db7bccf4STejun Heo gcwq->trustee_state == state || 3144db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE); 3145db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3146db7bccf4STejun Heo } 3147db7bccf4STejun Heo } 3148db7bccf4STejun Heo 31499c7b216dSChandra Seetharaman static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 31501da177e4SLinus Torvalds unsigned long action, 31511da177e4SLinus Torvalds void *hcpu) 31521da177e4SLinus Torvalds { 31533af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 3154db7bccf4STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3155db7bccf4STejun Heo struct task_struct *new_trustee = NULL; 3156e22bee78STejun Heo struct worker *uninitialized_var(new_worker); 3157db7bccf4STejun Heo unsigned long flags; 31581da177e4SLinus Torvalds 31598bb78442SRafael J. Wysocki action &= ~CPU_TASKS_FROZEN; 31608bb78442SRafael J. Wysocki 3161db7bccf4STejun Heo switch (action) { 3162db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3163db7bccf4STejun Heo new_trustee = kthread_create(trustee_thread, gcwq, 3164db7bccf4STejun Heo "workqueue_trustee/%d\n", cpu); 3165db7bccf4STejun Heo if (IS_ERR(new_trustee)) 3166db7bccf4STejun Heo return notifier_from_errno(PTR_ERR(new_trustee)); 3167db7bccf4STejun Heo kthread_bind(new_trustee, cpu); 3168e22bee78STejun Heo /* fall through */ 3169e22bee78STejun Heo case CPU_UP_PREPARE: 3170e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3171e22bee78STejun Heo new_worker = create_worker(gcwq, false); 3172e22bee78STejun Heo if (!new_worker) { 3173e22bee78STejun Heo if (new_trustee) 3174e22bee78STejun Heo kthread_stop(new_trustee); 3175e22bee78STejun Heo return NOTIFY_BAD; 3176e22bee78STejun Heo } 3177db7bccf4STejun Heo } 31781537663fSTejun Heo 3179db7bccf4STejun Heo /* some are called w/ irq disabled, don't disturb irq status */ 3180db7bccf4STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 31813af24433SOleg Nesterov 31823af24433SOleg Nesterov switch (action) { 3183db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3184db7bccf4STejun Heo /* initialize trustee and tell it to acquire the gcwq */ 3185db7bccf4STejun Heo BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); 3186db7bccf4STejun Heo gcwq->trustee = new_trustee; 3187db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_START; 3188db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3189db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); 3190e22bee78STejun Heo /* fall through */ 3191e22bee78STejun Heo case CPU_UP_PREPARE: 3192e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3193e22bee78STejun Heo gcwq->first_idle = new_worker; 3194e22bee78STejun Heo break; 3195e22bee78STejun Heo 3196e22bee78STejun Heo case CPU_DYING: 3197e22bee78STejun Heo /* 3198e22bee78STejun Heo * Before this, the trustee and all workers except for 3199e22bee78STejun Heo * the ones which are still executing works from 3200e22bee78STejun Heo * before the last CPU down must be on the cpu. After 3201e22bee78STejun Heo * this, they'll all be diasporas. 3202e22bee78STejun Heo */ 3203e22bee78STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 3204db7bccf4STejun Heo break; 3205db7bccf4STejun Heo 32063da1c84cSOleg Nesterov case CPU_POST_DEAD: 3207db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_BUTCHER; 3208e22bee78STejun Heo /* fall through */ 3209e22bee78STejun Heo case CPU_UP_CANCELED: 3210e22bee78STejun Heo destroy_worker(gcwq->first_idle); 3211e22bee78STejun Heo gcwq->first_idle = NULL; 3212db7bccf4STejun Heo break; 3213db7bccf4STejun Heo 3214db7bccf4STejun Heo case CPU_DOWN_FAILED: 3215db7bccf4STejun Heo case CPU_ONLINE: 3216e22bee78STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3217db7bccf4STejun Heo if (gcwq->trustee_state != TRUSTEE_DONE) { 3218db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_RELEASE; 3219db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3220db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_DONE); 3221db7bccf4STejun Heo } 3222db7bccf4STejun Heo 3223e22bee78STejun Heo /* 3224e22bee78STejun Heo * Trustee is done and there might be no worker left. 3225e22bee78STejun Heo * Put the first_idle in and request a real manager to 3226e22bee78STejun Heo * take a look. 3227e22bee78STejun Heo */ 3228e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3229e22bee78STejun Heo kthread_bind(gcwq->first_idle->task, cpu); 3230e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3231e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 3232e22bee78STejun Heo start_worker(gcwq->first_idle); 3233e22bee78STejun Heo gcwq->first_idle = NULL; 32341da177e4SLinus Torvalds break; 32351da177e4SLinus Torvalds } 3236db7bccf4STejun Heo 3237db7bccf4STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 32381da177e4SLinus Torvalds 32391537663fSTejun Heo return notifier_from_errno(0); 32401da177e4SLinus Torvalds } 32411da177e4SLinus Torvalds 32422d3854a3SRusty Russell #ifdef CONFIG_SMP 32438ccad40dSRusty Russell 32442d3854a3SRusty Russell struct work_for_cpu { 32456b44003eSAndrew Morton struct completion completion; 32462d3854a3SRusty Russell long (*fn)(void *); 32472d3854a3SRusty Russell void *arg; 32482d3854a3SRusty Russell long ret; 32492d3854a3SRusty Russell }; 32502d3854a3SRusty Russell 32516b44003eSAndrew Morton static int do_work_for_cpu(void *_wfc) 32522d3854a3SRusty Russell { 32536b44003eSAndrew Morton struct work_for_cpu *wfc = _wfc; 32542d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 32556b44003eSAndrew Morton complete(&wfc->completion); 32566b44003eSAndrew Morton return 0; 32572d3854a3SRusty Russell } 32582d3854a3SRusty Russell 32592d3854a3SRusty Russell /** 32602d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 32612d3854a3SRusty Russell * @cpu: the cpu to run on 32622d3854a3SRusty Russell * @fn: the function to run 32632d3854a3SRusty Russell * @arg: the function arg 32642d3854a3SRusty Russell * 326531ad9081SRusty Russell * This will return the value @fn returns. 326631ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 32676b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 32682d3854a3SRusty Russell */ 32692d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 32702d3854a3SRusty Russell { 32716b44003eSAndrew Morton struct task_struct *sub_thread; 32726b44003eSAndrew Morton struct work_for_cpu wfc = { 32736b44003eSAndrew Morton .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), 32746b44003eSAndrew Morton .fn = fn, 32756b44003eSAndrew Morton .arg = arg, 32766b44003eSAndrew Morton }; 32772d3854a3SRusty Russell 32786b44003eSAndrew Morton sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); 32796b44003eSAndrew Morton if (IS_ERR(sub_thread)) 32806b44003eSAndrew Morton return PTR_ERR(sub_thread); 32816b44003eSAndrew Morton kthread_bind(sub_thread, cpu); 32826b44003eSAndrew Morton wake_up_process(sub_thread); 32836b44003eSAndrew Morton wait_for_completion(&wfc.completion); 32842d3854a3SRusty Russell return wfc.ret; 32852d3854a3SRusty Russell } 32862d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 32872d3854a3SRusty Russell #endif /* CONFIG_SMP */ 32882d3854a3SRusty Russell 3289a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3290a0a1a5fdSTejun Heo 3291a0a1a5fdSTejun Heo /** 3292a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3293a0a1a5fdSTejun Heo * 3294a0a1a5fdSTejun Heo * Start freezing workqueues. After this function returns, all 3295a0a1a5fdSTejun Heo * freezeable workqueues will queue new works to their frozen_works 32967e11629dSTejun Heo * list instead of gcwq->worklist. 3297a0a1a5fdSTejun Heo * 3298a0a1a5fdSTejun Heo * CONTEXT: 32998b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3300a0a1a5fdSTejun Heo */ 3301a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3302a0a1a5fdSTejun Heo { 3303a0a1a5fdSTejun Heo struct workqueue_struct *wq; 3304a0a1a5fdSTejun Heo unsigned int cpu; 3305a0a1a5fdSTejun Heo 3306a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3307a0a1a5fdSTejun Heo 3308a0a1a5fdSTejun Heo BUG_ON(workqueue_freezing); 3309a0a1a5fdSTejun Heo workqueue_freezing = true; 3310a0a1a5fdSTejun Heo 3311a0a1a5fdSTejun Heo for_each_possible_cpu(cpu) { 33128b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 33138b03ae3cSTejun Heo 33148b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 33158b03ae3cSTejun Heo 3316db7bccf4STejun Heo BUG_ON(gcwq->flags & GCWQ_FREEZING); 3317db7bccf4STejun Heo gcwq->flags |= GCWQ_FREEZING; 3318db7bccf4STejun Heo 3319a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3320a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3321a0a1a5fdSTejun Heo 3322a0a1a5fdSTejun Heo if (wq->flags & WQ_FREEZEABLE) 3323a0a1a5fdSTejun Heo cwq->max_active = 0; 3324a0a1a5fdSTejun Heo } 33258b03ae3cSTejun Heo 33268b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3327a0a1a5fdSTejun Heo } 3328a0a1a5fdSTejun Heo 3329a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3330a0a1a5fdSTejun Heo } 3331a0a1a5fdSTejun Heo 3332a0a1a5fdSTejun Heo /** 3333a0a1a5fdSTejun Heo * freeze_workqueues_busy - are freezeable workqueues still busy? 3334a0a1a5fdSTejun Heo * 3335a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3336a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3337a0a1a5fdSTejun Heo * 3338a0a1a5fdSTejun Heo * CONTEXT: 3339a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3340a0a1a5fdSTejun Heo * 3341a0a1a5fdSTejun Heo * RETURNS: 3342a0a1a5fdSTejun Heo * %true if some freezeable workqueues are still busy. %false if 3343a0a1a5fdSTejun Heo * freezing is complete. 3344a0a1a5fdSTejun Heo */ 3345a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3346a0a1a5fdSTejun Heo { 3347a0a1a5fdSTejun Heo struct workqueue_struct *wq; 3348a0a1a5fdSTejun Heo unsigned int cpu; 3349a0a1a5fdSTejun Heo bool busy = false; 3350a0a1a5fdSTejun Heo 3351a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3352a0a1a5fdSTejun Heo 3353a0a1a5fdSTejun Heo BUG_ON(!workqueue_freezing); 3354a0a1a5fdSTejun Heo 3355a0a1a5fdSTejun Heo for_each_possible_cpu(cpu) { 3356a0a1a5fdSTejun Heo /* 3357a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3358a0a1a5fdSTejun Heo * to peek without lock. 3359a0a1a5fdSTejun Heo */ 3360a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3361a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3362a0a1a5fdSTejun Heo 3363a0a1a5fdSTejun Heo if (!(wq->flags & WQ_FREEZEABLE)) 3364a0a1a5fdSTejun Heo continue; 3365a0a1a5fdSTejun Heo 3366a0a1a5fdSTejun Heo BUG_ON(cwq->nr_active < 0); 3367a0a1a5fdSTejun Heo if (cwq->nr_active) { 3368a0a1a5fdSTejun Heo busy = true; 3369a0a1a5fdSTejun Heo goto out_unlock; 3370a0a1a5fdSTejun Heo } 3371a0a1a5fdSTejun Heo } 3372a0a1a5fdSTejun Heo } 3373a0a1a5fdSTejun Heo out_unlock: 3374a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3375a0a1a5fdSTejun Heo return busy; 3376a0a1a5fdSTejun Heo } 3377a0a1a5fdSTejun Heo 3378a0a1a5fdSTejun Heo /** 3379a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3380a0a1a5fdSTejun Heo * 3381a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 33827e11629dSTejun Heo * frozen works are transferred to their respective gcwq worklists. 3383a0a1a5fdSTejun Heo * 3384a0a1a5fdSTejun Heo * CONTEXT: 33858b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3386a0a1a5fdSTejun Heo */ 3387a0a1a5fdSTejun Heo void thaw_workqueues(void) 3388a0a1a5fdSTejun Heo { 3389a0a1a5fdSTejun Heo struct workqueue_struct *wq; 3390a0a1a5fdSTejun Heo unsigned int cpu; 3391a0a1a5fdSTejun Heo 3392a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3393a0a1a5fdSTejun Heo 3394a0a1a5fdSTejun Heo if (!workqueue_freezing) 3395a0a1a5fdSTejun Heo goto out_unlock; 3396a0a1a5fdSTejun Heo 3397a0a1a5fdSTejun Heo for_each_possible_cpu(cpu) { 33988b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 33998b03ae3cSTejun Heo 34008b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 34018b03ae3cSTejun Heo 3402db7bccf4STejun Heo BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); 3403db7bccf4STejun Heo gcwq->flags &= ~GCWQ_FREEZING; 3404db7bccf4STejun Heo 3405a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3406a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3407a0a1a5fdSTejun Heo 3408a0a1a5fdSTejun Heo if (!(wq->flags & WQ_FREEZEABLE)) 3409a0a1a5fdSTejun Heo continue; 3410a0a1a5fdSTejun Heo 3411a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 3412a0a1a5fdSTejun Heo cwq->max_active = wq->saved_max_active; 3413a0a1a5fdSTejun Heo 3414a0a1a5fdSTejun Heo while (!list_empty(&cwq->delayed_works) && 3415a0a1a5fdSTejun Heo cwq->nr_active < cwq->max_active) 3416a0a1a5fdSTejun Heo cwq_activate_first_delayed(cwq); 3417a0a1a5fdSTejun Heo 3418502ca9d8STejun Heo /* perform delayed unbind from single cpu if empty */ 3419502ca9d8STejun Heo if (wq->single_cpu == gcwq->cpu && 3420502ca9d8STejun Heo !cwq->nr_active && list_empty(&cwq->delayed_works)) 3421502ca9d8STejun Heo cwq_unbind_single_cpu(cwq); 3422a0a1a5fdSTejun Heo } 34238b03ae3cSTejun Heo 3424e22bee78STejun Heo wake_up_worker(gcwq); 3425e22bee78STejun Heo 34268b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3427a0a1a5fdSTejun Heo } 3428a0a1a5fdSTejun Heo 3429a0a1a5fdSTejun Heo workqueue_freezing = false; 3430a0a1a5fdSTejun Heo out_unlock: 3431a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3432a0a1a5fdSTejun Heo } 3433a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3434a0a1a5fdSTejun Heo 3435c12920d1SOleg Nesterov void __init init_workqueues(void) 34361da177e4SLinus Torvalds { 3437c34056a3STejun Heo unsigned int cpu; 3438c8e55f36STejun Heo int i; 3439c34056a3STejun Heo 34407a22ad75STejun Heo /* 34417a22ad75STejun Heo * The pointer part of work->data is either pointing to the 34427a22ad75STejun Heo * cwq or contains the cpu number the work ran last on. Make 34437a22ad75STejun Heo * sure cpu number won't overflow into kernel pointer area so 34447a22ad75STejun Heo * that they can be distinguished. 34457a22ad75STejun Heo */ 34467a22ad75STejun Heo BUILD_BUG_ON(NR_CPUS << WORK_STRUCT_FLAG_BITS >= PAGE_OFFSET); 34477a22ad75STejun Heo 3448db7bccf4STejun Heo hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); 34498b03ae3cSTejun Heo 34508b03ae3cSTejun Heo /* initialize gcwqs */ 34518b03ae3cSTejun Heo for_each_possible_cpu(cpu) { 34528b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 34538b03ae3cSTejun Heo 34548b03ae3cSTejun Heo spin_lock_init(&gcwq->lock); 34557e11629dSTejun Heo INIT_LIST_HEAD(&gcwq->worklist); 34568b03ae3cSTejun Heo gcwq->cpu = cpu; 34578b03ae3cSTejun Heo 3458c8e55f36STejun Heo INIT_LIST_HEAD(&gcwq->idle_list); 3459c8e55f36STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) 3460c8e55f36STejun Heo INIT_HLIST_HEAD(&gcwq->busy_hash[i]); 3461c8e55f36STejun Heo 3462e22bee78STejun Heo init_timer_deferrable(&gcwq->idle_timer); 3463e22bee78STejun Heo gcwq->idle_timer.function = idle_worker_timeout; 3464e22bee78STejun Heo gcwq->idle_timer.data = (unsigned long)gcwq; 3465e22bee78STejun Heo 3466e22bee78STejun Heo setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, 3467e22bee78STejun Heo (unsigned long)gcwq); 3468e22bee78STejun Heo 34698b03ae3cSTejun Heo ida_init(&gcwq->worker_ida); 3470db7bccf4STejun Heo 3471db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3472db7bccf4STejun Heo init_waitqueue_head(&gcwq->trustee_wait); 34738b03ae3cSTejun Heo } 34748b03ae3cSTejun Heo 3475e22bee78STejun Heo /* create the initial worker */ 3476e22bee78STejun Heo for_each_online_cpu(cpu) { 3477e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3478e22bee78STejun Heo struct worker *worker; 3479e22bee78STejun Heo 3480e22bee78STejun Heo worker = create_worker(gcwq, true); 3481e22bee78STejun Heo BUG_ON(!worker); 3482e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3483e22bee78STejun Heo start_worker(worker); 3484e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3485e22bee78STejun Heo } 3486e22bee78STejun Heo 3487d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 3488d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3489d320c038STejun Heo system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); 3490d320c038STejun Heo BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq); 34911da177e4SLinus Torvalds } 3492