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 */ 56f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 57e22bee78STejun Heo 58fb0e7bebSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | 59f3421797STejun Heo WORKER_CPU_INTENSIVE | WORKER_UNBOUND, 60db7bccf4STejun Heo 61db7bccf4STejun Heo /* gcwq->trustee_state */ 62db7bccf4STejun Heo TRUSTEE_START = 0, /* start */ 63db7bccf4STejun Heo TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ 64db7bccf4STejun Heo TRUSTEE_BUTCHER = 2, /* butcher workers */ 65db7bccf4STejun Heo TRUSTEE_RELEASE = 3, /* release workers */ 66db7bccf4STejun Heo TRUSTEE_DONE = 4, /* trustee is done */ 67c8e55f36STejun Heo 68c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 69c8e55f36STejun Heo BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, 70c8e55f36STejun Heo BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, 71db7bccf4STejun Heo 72e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 73e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 74e22bee78STejun Heo 75e22bee78STejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */ 76e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 77e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 78db7bccf4STejun Heo TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ 79e22bee78STejun Heo 80e22bee78STejun Heo /* 81e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 82e22bee78STejun Heo * all cpus. Give -20. 83e22bee78STejun Heo */ 84e22bee78STejun Heo RESCUER_NICE_LEVEL = -20, 85c8e55f36STejun Heo }; 86c8e55f36STejun Heo 871da177e4SLinus Torvalds /* 884690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 894690c4abSTejun Heo * 904690c4abSTejun Heo * I: Set during initialization and read-only afterwards. 914690c4abSTejun Heo * 92e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 93e22bee78STejun Heo * only be modified and accessed from the local cpu. 94e22bee78STejun Heo * 958b03ae3cSTejun Heo * L: gcwq->lock protected. Access with gcwq->lock held. 964690c4abSTejun Heo * 97e22bee78STejun Heo * X: During normal operation, modification requires gcwq->lock and 98e22bee78STejun Heo * should be done only from local cpu. Either disabling preemption 99e22bee78STejun Heo * on local cpu or grabbing gcwq->lock is enough for read access. 100f3421797STejun Heo * If GCWQ_DISASSOCIATED is set, it's identical to L. 101e22bee78STejun Heo * 10273f53c4aSTejun Heo * F: wq->flush_mutex protected. 10373f53c4aSTejun Heo * 1044690c4abSTejun Heo * W: workqueue_lock protected. 1054690c4abSTejun Heo */ 1064690c4abSTejun Heo 1078b03ae3cSTejun Heo struct global_cwq; 108c34056a3STejun Heo 109e22bee78STejun Heo /* 110e22bee78STejun Heo * The poor guys doing the actual heavy lifting. All on-duty workers 111e22bee78STejun Heo * are either serving the manager role, on idle list or on busy hash. 112e22bee78STejun Heo */ 113c34056a3STejun Heo struct worker { 114c8e55f36STejun Heo /* on idle list while idle, on busy hash table while busy */ 115c8e55f36STejun Heo union { 116c8e55f36STejun Heo struct list_head entry; /* L: while idle */ 117c8e55f36STejun Heo struct hlist_node hentry; /* L: while busy */ 118c8e55f36STejun Heo }; 119c8e55f36STejun Heo 120c34056a3STejun Heo struct work_struct *current_work; /* L: work being processed */ 1218cca0eeaSTejun Heo struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ 122affee4b2STejun Heo struct list_head scheduled; /* L: scheduled works */ 123c34056a3STejun Heo struct task_struct *task; /* I: worker task */ 1248b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 125e22bee78STejun Heo /* 64 bytes boundary on 64bit, 32 on 32bit */ 126e22bee78STejun Heo unsigned long last_active; /* L: last active timestamp */ 127e22bee78STejun Heo unsigned int flags; /* X: flags */ 128c34056a3STejun Heo int id; /* I: worker id */ 129e22bee78STejun Heo struct work_struct rebind_work; /* L: rebind worker to cpu */ 130c34056a3STejun Heo }; 131c34056a3STejun Heo 1324690c4abSTejun Heo /* 133e22bee78STejun Heo * Global per-cpu workqueue. There's one and only one for each cpu 134e22bee78STejun Heo * and all works are queued and processed here regardless of their 135e22bee78STejun Heo * target workqueues. 1368b03ae3cSTejun Heo */ 1378b03ae3cSTejun Heo struct global_cwq { 1388b03ae3cSTejun Heo spinlock_t lock; /* the gcwq lock */ 1397e11629dSTejun Heo struct list_head worklist; /* L: list of pending works */ 1408b03ae3cSTejun Heo unsigned int cpu; /* I: the associated cpu */ 141db7bccf4STejun Heo unsigned int flags; /* L: GCWQ_* flags */ 142c8e55f36STejun Heo 143c8e55f36STejun Heo int nr_workers; /* L: total number of workers */ 144c8e55f36STejun Heo int nr_idle; /* L: currently idle ones */ 145c8e55f36STejun Heo 146c8e55f36STejun Heo /* workers are chained either in the idle_list or busy_hash */ 147e22bee78STejun Heo struct list_head idle_list; /* X: list of idle workers */ 148c8e55f36STejun Heo struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; 149c8e55f36STejun Heo /* L: hash of busy workers */ 150c8e55f36STejun Heo 151e22bee78STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 152e22bee78STejun Heo struct timer_list mayday_timer; /* L: SOS timer for dworkers */ 153e22bee78STejun Heo 1548b03ae3cSTejun Heo struct ida worker_ida; /* L: for worker IDs */ 155db7bccf4STejun Heo 156db7bccf4STejun Heo struct task_struct *trustee; /* L: for gcwq shutdown */ 157db7bccf4STejun Heo unsigned int trustee_state; /* L: trustee state */ 158db7bccf4STejun Heo wait_queue_head_t trustee_wait; /* trustee wait */ 159e22bee78STejun Heo struct worker *first_idle; /* L: first idle worker */ 1608b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1618b03ae3cSTejun Heo 1628b03ae3cSTejun Heo /* 163502ca9d8STejun Heo * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of 1640f900049STejun Heo * work_struct->data are used for flags and thus cwqs need to be 1650f900049STejun Heo * aligned at two's power of the number of flag bits. 1661da177e4SLinus Torvalds */ 1671da177e4SLinus Torvalds struct cpu_workqueue_struct { 1688b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 1694690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 17073f53c4aSTejun Heo int work_color; /* L: current color */ 17173f53c4aSTejun Heo int flush_color; /* L: flushing color */ 17273f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 17373f53c4aSTejun Heo /* L: nr of in_flight works */ 1741e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 175a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 1761e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 1770f900049STejun Heo }; 1781da177e4SLinus Torvalds 1791da177e4SLinus Torvalds /* 18073f53c4aSTejun Heo * Structure used to wait for workqueue flush. 18173f53c4aSTejun Heo */ 18273f53c4aSTejun Heo struct wq_flusher { 18373f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 18473f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 18573f53c4aSTejun Heo struct completion done; /* flush completion */ 18673f53c4aSTejun Heo }; 18773f53c4aSTejun Heo 18873f53c4aSTejun Heo /* 189f2e005aaSTejun Heo * All cpumasks are assumed to be always set on UP and thus can't be 190f2e005aaSTejun Heo * used to determine whether there's something to be done. 191f2e005aaSTejun Heo */ 192f2e005aaSTejun Heo #ifdef CONFIG_SMP 193f2e005aaSTejun Heo typedef cpumask_var_t mayday_mask_t; 194f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) \ 195f2e005aaSTejun Heo cpumask_test_and_set_cpu((cpu), (mask)) 196f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) 197f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) 198f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) alloc_cpumask_var((maskp), (gfp)) 199f2e005aaSTejun Heo #define free_mayday_mask(mask) free_cpumask_var((mask)) 200f2e005aaSTejun Heo #else 201f2e005aaSTejun Heo typedef unsigned long mayday_mask_t; 202f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) 203f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) 204f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) 205f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) true 206f2e005aaSTejun Heo #define free_mayday_mask(mask) do { } while (0) 207f2e005aaSTejun Heo #endif 208f2e005aaSTejun Heo 209f2e005aaSTejun Heo /* 2101da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 2111da177e4SLinus Torvalds * per-CPU workqueues: 2121da177e4SLinus Torvalds */ 2131da177e4SLinus Torvalds struct workqueue_struct { 21497e37d7bSTejun Heo unsigned int flags; /* I: WQ_* flags */ 215bdbc5dd7STejun Heo union { 216bdbc5dd7STejun Heo struct cpu_workqueue_struct __percpu *pcpu; 217bdbc5dd7STejun Heo struct cpu_workqueue_struct *single; 218bdbc5dd7STejun Heo unsigned long v; 219bdbc5dd7STejun Heo } cpu_wq; /* I: cwq's */ 2204690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 22173f53c4aSTejun Heo 22273f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 22373f53c4aSTejun Heo int work_color; /* F: current work color */ 22473f53c4aSTejun Heo int flush_color; /* F: current flush color */ 22573f53c4aSTejun Heo atomic_t nr_cwqs_to_flush; /* flush in progress */ 22673f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 22773f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 22873f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 22973f53c4aSTejun Heo 230f2e005aaSTejun Heo mayday_mask_t mayday_mask; /* cpus requesting rescue */ 231e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 232e22bee78STejun Heo 233dcd989cbSTejun Heo int saved_max_active; /* W: saved cwq max_active */ 2344690c4abSTejun Heo const char *name; /* I: workqueue name */ 2354e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2364e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2374e6045f1SJohannes Berg #endif 2381da177e4SLinus Torvalds }; 2391da177e4SLinus Torvalds 240d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 241d320c038STejun Heo struct workqueue_struct *system_long_wq __read_mostly; 242d320c038STejun Heo struct workqueue_struct *system_nrt_wq __read_mostly; 243f3421797STejun Heo struct workqueue_struct *system_unbound_wq __read_mostly; 244d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 245d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 246d320c038STejun Heo EXPORT_SYMBOL_GPL(system_nrt_wq); 247f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 248d320c038STejun Heo 249db7bccf4STejun Heo #define for_each_busy_worker(worker, i, pos, gcwq) \ 250db7bccf4STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ 251db7bccf4STejun Heo hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) 252db7bccf4STejun Heo 253f3421797STejun Heo static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, 254f3421797STejun Heo unsigned int sw) 255f3421797STejun Heo { 256f3421797STejun Heo if (cpu < nr_cpu_ids) { 257f3421797STejun Heo if (sw & 1) { 258f3421797STejun Heo cpu = cpumask_next(cpu, mask); 259f3421797STejun Heo if (cpu < nr_cpu_ids) 260f3421797STejun Heo return cpu; 261f3421797STejun Heo } 262f3421797STejun Heo if (sw & 2) 263f3421797STejun Heo return WORK_CPU_UNBOUND; 264f3421797STejun Heo } 265f3421797STejun Heo return WORK_CPU_NONE; 266f3421797STejun Heo } 267f3421797STejun Heo 268f3421797STejun Heo static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, 269f3421797STejun Heo struct workqueue_struct *wq) 270f3421797STejun Heo { 271f3421797STejun Heo return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); 272f3421797STejun Heo } 273f3421797STejun Heo 274f3421797STejun Heo #define for_each_gcwq_cpu(cpu) \ 275f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ 276f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 277f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) 278f3421797STejun Heo 279f3421797STejun Heo #define for_each_online_gcwq_cpu(cpu) \ 280f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ 281f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 282f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) 283f3421797STejun Heo 284f3421797STejun Heo #define for_each_cwq_cpu(cpu, wq) \ 285f3421797STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ 286f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 287f3421797STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) 288f3421797STejun Heo 289dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 290dc186ad7SThomas Gleixner 291dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 292dc186ad7SThomas Gleixner 293dc186ad7SThomas Gleixner /* 294dc186ad7SThomas Gleixner * fixup_init is called when: 295dc186ad7SThomas Gleixner * - an active object is initialized 296dc186ad7SThomas Gleixner */ 297dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 298dc186ad7SThomas Gleixner { 299dc186ad7SThomas Gleixner struct work_struct *work = addr; 300dc186ad7SThomas Gleixner 301dc186ad7SThomas Gleixner switch (state) { 302dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 303dc186ad7SThomas Gleixner cancel_work_sync(work); 304dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 305dc186ad7SThomas Gleixner return 1; 306dc186ad7SThomas Gleixner default: 307dc186ad7SThomas Gleixner return 0; 308dc186ad7SThomas Gleixner } 309dc186ad7SThomas Gleixner } 310dc186ad7SThomas Gleixner 311dc186ad7SThomas Gleixner /* 312dc186ad7SThomas Gleixner * fixup_activate is called when: 313dc186ad7SThomas Gleixner * - an active object is activated 314dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 315dc186ad7SThomas Gleixner */ 316dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 317dc186ad7SThomas Gleixner { 318dc186ad7SThomas Gleixner struct work_struct *work = addr; 319dc186ad7SThomas Gleixner 320dc186ad7SThomas Gleixner switch (state) { 321dc186ad7SThomas Gleixner 322dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 323dc186ad7SThomas Gleixner /* 324dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 325dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 326dc186ad7SThomas Gleixner * is tracked in the object tracker. 327dc186ad7SThomas Gleixner */ 32822df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 329dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 330dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 331dc186ad7SThomas Gleixner return 0; 332dc186ad7SThomas Gleixner } 333dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 334dc186ad7SThomas Gleixner return 0; 335dc186ad7SThomas Gleixner 336dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 337dc186ad7SThomas Gleixner WARN_ON(1); 338dc186ad7SThomas Gleixner 339dc186ad7SThomas Gleixner default: 340dc186ad7SThomas Gleixner return 0; 341dc186ad7SThomas Gleixner } 342dc186ad7SThomas Gleixner } 343dc186ad7SThomas Gleixner 344dc186ad7SThomas Gleixner /* 345dc186ad7SThomas Gleixner * fixup_free is called when: 346dc186ad7SThomas Gleixner * - an active object is freed 347dc186ad7SThomas Gleixner */ 348dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 349dc186ad7SThomas Gleixner { 350dc186ad7SThomas Gleixner struct work_struct *work = addr; 351dc186ad7SThomas Gleixner 352dc186ad7SThomas Gleixner switch (state) { 353dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 354dc186ad7SThomas Gleixner cancel_work_sync(work); 355dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 356dc186ad7SThomas Gleixner return 1; 357dc186ad7SThomas Gleixner default: 358dc186ad7SThomas Gleixner return 0; 359dc186ad7SThomas Gleixner } 360dc186ad7SThomas Gleixner } 361dc186ad7SThomas Gleixner 362dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 363dc186ad7SThomas Gleixner .name = "work_struct", 364dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 365dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 366dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 367dc186ad7SThomas Gleixner }; 368dc186ad7SThomas Gleixner 369dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 370dc186ad7SThomas Gleixner { 371dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 372dc186ad7SThomas Gleixner } 373dc186ad7SThomas Gleixner 374dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 375dc186ad7SThomas Gleixner { 376dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 377dc186ad7SThomas Gleixner } 378dc186ad7SThomas Gleixner 379dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 380dc186ad7SThomas Gleixner { 381dc186ad7SThomas Gleixner if (onstack) 382dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 383dc186ad7SThomas Gleixner else 384dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 385dc186ad7SThomas Gleixner } 386dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 387dc186ad7SThomas Gleixner 388dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 389dc186ad7SThomas Gleixner { 390dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 391dc186ad7SThomas Gleixner } 392dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 393dc186ad7SThomas Gleixner 394dc186ad7SThomas Gleixner #else 395dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 396dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 397dc186ad7SThomas Gleixner #endif 398dc186ad7SThomas Gleixner 39995402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 40095402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 4011da177e4SLinus Torvalds static LIST_HEAD(workqueues); 402a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 403c34056a3STejun Heo 404e22bee78STejun Heo /* 405e22bee78STejun Heo * The almighty global cpu workqueues. nr_running is the only field 406e22bee78STejun Heo * which is expected to be used frequently by other cpus via 407e22bee78STejun Heo * try_to_wake_up(). Put it in a separate cacheline. 408e22bee78STejun Heo */ 4098b03ae3cSTejun Heo static DEFINE_PER_CPU(struct global_cwq, global_cwq); 410e22bee78STejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); 4118b03ae3cSTejun Heo 412f3421797STejun Heo /* 413f3421797STejun Heo * Global cpu workqueue and nr_running counter for unbound gcwq. The 414f3421797STejun Heo * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its 415f3421797STejun Heo * workers have WORKER_UNBOUND set. 416f3421797STejun Heo */ 417f3421797STejun Heo static struct global_cwq unbound_global_cwq; 418f3421797STejun Heo static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ 419f3421797STejun Heo 420c34056a3STejun Heo static int worker_thread(void *__worker); 4211da177e4SLinus Torvalds 4228b03ae3cSTejun Heo static struct global_cwq *get_gcwq(unsigned int cpu) 4238b03ae3cSTejun Heo { 424f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 4258b03ae3cSTejun Heo return &per_cpu(global_cwq, cpu); 426f3421797STejun Heo else 427f3421797STejun Heo return &unbound_global_cwq; 4288b03ae3cSTejun Heo } 4298b03ae3cSTejun Heo 430e22bee78STejun Heo static atomic_t *get_gcwq_nr_running(unsigned int cpu) 431e22bee78STejun Heo { 432f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 433e22bee78STejun Heo return &per_cpu(gcwq_nr_running, cpu); 434f3421797STejun Heo else 435f3421797STejun Heo return &unbound_gcwq_nr_running; 436e22bee78STejun Heo } 437e22bee78STejun Heo 4384690c4abSTejun Heo static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, 4394690c4abSTejun Heo struct workqueue_struct *wq) 440a848e3b6SOleg Nesterov { 441f3421797STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 442f3421797STejun Heo if (likely(cpu < nr_cpu_ids)) { 443f3421797STejun Heo #ifdef CONFIG_SMP 444bdbc5dd7STejun Heo return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); 445f3421797STejun Heo #else 446f3421797STejun Heo return wq->cpu_wq.single; 447bdbc5dd7STejun Heo #endif 448a848e3b6SOleg Nesterov } 449f3421797STejun Heo } else if (likely(cpu == WORK_CPU_UNBOUND)) 450f3421797STejun Heo return wq->cpu_wq.single; 451f3421797STejun Heo return NULL; 452f3421797STejun Heo } 453a848e3b6SOleg Nesterov 45473f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 45573f53c4aSTejun Heo { 45673f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 45773f53c4aSTejun Heo } 45873f53c4aSTejun Heo 45973f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 46073f53c4aSTejun Heo { 46173f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 46273f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 46373f53c4aSTejun Heo } 46473f53c4aSTejun Heo 46573f53c4aSTejun Heo static int work_next_color(int color) 46673f53c4aSTejun Heo { 46773f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 46873f53c4aSTejun Heo } 46973f53c4aSTejun Heo 4704594bf15SDavid Howells /* 471e120153dSTejun Heo * A work's data points to the cwq with WORK_STRUCT_CWQ set while the 472e120153dSTejun Heo * work is on queue. Once execution starts, WORK_STRUCT_CWQ is 473e120153dSTejun Heo * cleared and the work data contains the cpu number it was last on. 4747a22ad75STejun Heo * 4757a22ad75STejun Heo * set_work_{cwq|cpu}() and clear_work_data() can be used to set the 4767a22ad75STejun Heo * cwq, cpu or clear work->data. These functions should only be 4777a22ad75STejun Heo * called while the work is owned - ie. while the PENDING bit is set. 4787a22ad75STejun Heo * 4797a22ad75STejun Heo * get_work_[g]cwq() can be used to obtain the gcwq or cwq 4807a22ad75STejun Heo * corresponding to a work. gcwq is available once the work has been 4817a22ad75STejun Heo * queued anywhere after initialization. cwq is available only from 4827a22ad75STejun Heo * queueing until execution starts. 4834594bf15SDavid Howells */ 4847a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 4857a22ad75STejun Heo unsigned long flags) 4867a22ad75STejun Heo { 4877a22ad75STejun Heo BUG_ON(!work_pending(work)); 4887a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 4897a22ad75STejun Heo } 4907a22ad75STejun Heo 4917a22ad75STejun Heo static void set_work_cwq(struct work_struct *work, 4924690c4abSTejun Heo struct cpu_workqueue_struct *cwq, 4934690c4abSTejun Heo unsigned long extra_flags) 494365970a1SDavid Howells { 4957a22ad75STejun Heo set_work_data(work, (unsigned long)cwq, 496e120153dSTejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); 497365970a1SDavid Howells } 498365970a1SDavid Howells 4997a22ad75STejun Heo static void set_work_cpu(struct work_struct *work, unsigned int cpu) 5004d707b9fSOleg Nesterov { 5017a22ad75STejun Heo set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); 5024d707b9fSOleg Nesterov } 5034d707b9fSOleg Nesterov 5047a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 505365970a1SDavid Howells { 5067a22ad75STejun Heo set_work_data(work, WORK_STRUCT_NO_CPU, 0); 5077a22ad75STejun Heo } 5087a22ad75STejun Heo 5097a22ad75STejun Heo static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) 5107a22ad75STejun Heo { 511e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5127a22ad75STejun Heo 513e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 514e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 515e120153dSTejun Heo else 516e120153dSTejun Heo return NULL; 5177a22ad75STejun Heo } 5187a22ad75STejun Heo 5197a22ad75STejun Heo static struct global_cwq *get_work_gcwq(struct work_struct *work) 5207a22ad75STejun Heo { 521e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5227a22ad75STejun Heo unsigned int cpu; 5237a22ad75STejun Heo 524e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 525e120153dSTejun Heo return ((struct cpu_workqueue_struct *) 526e120153dSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; 5277a22ad75STejun Heo 5287a22ad75STejun Heo cpu = data >> WORK_STRUCT_FLAG_BITS; 529bdbc5dd7STejun Heo if (cpu == WORK_CPU_NONE) 5307a22ad75STejun Heo return NULL; 5317a22ad75STejun Heo 532f3421797STejun Heo BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); 5337a22ad75STejun Heo return get_gcwq(cpu); 534365970a1SDavid Howells } 535365970a1SDavid Howells 536e22bee78STejun Heo /* 537e22bee78STejun Heo * Policy functions. These define the policies on how the global 538e22bee78STejun Heo * worker pool is managed. Unless noted otherwise, these functions 539e22bee78STejun Heo * assume that they're being called with gcwq->lock held. 540e22bee78STejun Heo */ 541e22bee78STejun Heo 542649027d7STejun Heo static bool __need_more_worker(struct global_cwq *gcwq) 543649027d7STejun Heo { 544649027d7STejun Heo return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || 545649027d7STejun Heo gcwq->flags & GCWQ_HIGHPRI_PENDING; 546649027d7STejun Heo } 547649027d7STejun Heo 548e22bee78STejun Heo /* 549e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 550e22bee78STejun Heo * running workers. 551e22bee78STejun Heo */ 552e22bee78STejun Heo static bool need_more_worker(struct global_cwq *gcwq) 553e22bee78STejun Heo { 554649027d7STejun Heo return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); 555e22bee78STejun Heo } 556e22bee78STejun Heo 557e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 558e22bee78STejun Heo static bool may_start_working(struct global_cwq *gcwq) 559e22bee78STejun Heo { 560e22bee78STejun Heo return gcwq->nr_idle; 561e22bee78STejun Heo } 562e22bee78STejun Heo 563e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 564e22bee78STejun Heo static bool keep_working(struct global_cwq *gcwq) 565e22bee78STejun Heo { 566e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 567e22bee78STejun Heo 568e22bee78STejun Heo return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1; 569e22bee78STejun Heo } 570e22bee78STejun Heo 571e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 572e22bee78STejun Heo static bool need_to_create_worker(struct global_cwq *gcwq) 573e22bee78STejun Heo { 574e22bee78STejun Heo return need_more_worker(gcwq) && !may_start_working(gcwq); 575e22bee78STejun Heo } 576e22bee78STejun Heo 577e22bee78STejun Heo /* Do I need to be the manager? */ 578e22bee78STejun Heo static bool need_to_manage_workers(struct global_cwq *gcwq) 579e22bee78STejun Heo { 580e22bee78STejun Heo return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; 581e22bee78STejun Heo } 582e22bee78STejun Heo 583e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 584e22bee78STejun Heo static bool too_many_workers(struct global_cwq *gcwq) 585e22bee78STejun Heo { 586e22bee78STejun Heo bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; 587e22bee78STejun Heo int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ 588e22bee78STejun Heo int nr_busy = gcwq->nr_workers - nr_idle; 589e22bee78STejun Heo 590e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 591e22bee78STejun Heo } 592e22bee78STejun Heo 593e22bee78STejun Heo /* 594e22bee78STejun Heo * Wake up functions. 595e22bee78STejun Heo */ 596e22bee78STejun Heo 5977e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 5987e11629dSTejun Heo static struct worker *first_worker(struct global_cwq *gcwq) 5997e11629dSTejun Heo { 6007e11629dSTejun Heo if (unlikely(list_empty(&gcwq->idle_list))) 6017e11629dSTejun Heo return NULL; 6027e11629dSTejun Heo 6037e11629dSTejun Heo return list_first_entry(&gcwq->idle_list, struct worker, entry); 6047e11629dSTejun Heo } 6057e11629dSTejun Heo 6067e11629dSTejun Heo /** 6077e11629dSTejun Heo * wake_up_worker - wake up an idle worker 6087e11629dSTejun Heo * @gcwq: gcwq to wake worker for 6097e11629dSTejun Heo * 6107e11629dSTejun Heo * Wake up the first idle worker of @gcwq. 6117e11629dSTejun Heo * 6127e11629dSTejun Heo * CONTEXT: 6137e11629dSTejun Heo * spin_lock_irq(gcwq->lock). 6147e11629dSTejun Heo */ 6157e11629dSTejun Heo static void wake_up_worker(struct global_cwq *gcwq) 6167e11629dSTejun Heo { 6177e11629dSTejun Heo struct worker *worker = first_worker(gcwq); 6187e11629dSTejun Heo 6197e11629dSTejun Heo if (likely(worker)) 6207e11629dSTejun Heo wake_up_process(worker->task); 6217e11629dSTejun Heo } 6227e11629dSTejun Heo 6234690c4abSTejun Heo /** 624e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 625e22bee78STejun Heo * @task: task waking up 626e22bee78STejun Heo * @cpu: CPU @task is waking up to 627e22bee78STejun Heo * 628e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 629e22bee78STejun Heo * being awoken. 630e22bee78STejun Heo * 631e22bee78STejun Heo * CONTEXT: 632e22bee78STejun Heo * spin_lock_irq(rq->lock) 633e22bee78STejun Heo */ 634e22bee78STejun Heo void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) 635e22bee78STejun Heo { 636e22bee78STejun Heo struct worker *worker = kthread_data(task); 637e22bee78STejun Heo 638e22bee78STejun Heo if (likely(!(worker->flags & WORKER_NOT_RUNNING))) 639e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(cpu)); 640e22bee78STejun Heo } 641e22bee78STejun Heo 642e22bee78STejun Heo /** 643e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 644e22bee78STejun Heo * @task: task going to sleep 645e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 646e22bee78STejun Heo * 647e22bee78STejun Heo * This function is called during schedule() when a busy worker is 648e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 649e22bee78STejun Heo * returning pointer to its task. 650e22bee78STejun Heo * 651e22bee78STejun Heo * CONTEXT: 652e22bee78STejun Heo * spin_lock_irq(rq->lock) 653e22bee78STejun Heo * 654e22bee78STejun Heo * RETURNS: 655e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 656e22bee78STejun Heo */ 657e22bee78STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, 658e22bee78STejun Heo unsigned int cpu) 659e22bee78STejun Heo { 660e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 661e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 662e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(cpu); 663e22bee78STejun Heo 664e22bee78STejun Heo if (unlikely(worker->flags & WORKER_NOT_RUNNING)) 665e22bee78STejun Heo return NULL; 666e22bee78STejun Heo 667e22bee78STejun Heo /* this can only happen on the local cpu */ 668e22bee78STejun Heo BUG_ON(cpu != raw_smp_processor_id()); 669e22bee78STejun Heo 670e22bee78STejun Heo /* 671e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 672e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 673e22bee78STejun Heo * Please read comment there. 674e22bee78STejun Heo * 675e22bee78STejun Heo * NOT_RUNNING is clear. This means that trustee is not in 676e22bee78STejun Heo * charge and we're running on the local cpu w/ rq lock held 677e22bee78STejun Heo * and preemption disabled, which in turn means that none else 678e22bee78STejun Heo * could be manipulating idle_list, so dereferencing idle_list 679e22bee78STejun Heo * without gcwq lock is safe. 680e22bee78STejun Heo */ 681e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) 682e22bee78STejun Heo to_wakeup = first_worker(gcwq); 683e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 684e22bee78STejun Heo } 685e22bee78STejun Heo 686e22bee78STejun Heo /** 687e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 688cb444766STejun Heo * @worker: self 689d302f017STejun Heo * @flags: flags to set 690d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 691d302f017STejun Heo * 692e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 693e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 694e22bee78STejun Heo * woken up. 695d302f017STejun Heo * 696cb444766STejun Heo * CONTEXT: 697cb444766STejun Heo * spin_lock_irq(gcwq->lock) 698d302f017STejun Heo */ 699d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 700d302f017STejun Heo bool wakeup) 701d302f017STejun Heo { 702e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 703e22bee78STejun Heo 704cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 705cb444766STejun Heo 706e22bee78STejun Heo /* 707e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 708e22bee78STejun Heo * wake up an idle worker as necessary if requested by 709e22bee78STejun Heo * @wakeup. 710e22bee78STejun Heo */ 711e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 712e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 713e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 714e22bee78STejun Heo 715e22bee78STejun Heo if (wakeup) { 716e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && 717e22bee78STejun Heo !list_empty(&gcwq->worklist)) 718e22bee78STejun Heo wake_up_worker(gcwq); 719e22bee78STejun Heo } else 720e22bee78STejun Heo atomic_dec(nr_running); 721e22bee78STejun Heo } 722e22bee78STejun Heo 723d302f017STejun Heo worker->flags |= flags; 724d302f017STejun Heo } 725d302f017STejun Heo 726d302f017STejun Heo /** 727e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 728cb444766STejun Heo * @worker: self 729d302f017STejun Heo * @flags: flags to clear 730d302f017STejun Heo * 731e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 732d302f017STejun Heo * 733cb444766STejun Heo * CONTEXT: 734cb444766STejun Heo * spin_lock_irq(gcwq->lock) 735d302f017STejun Heo */ 736d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 737d302f017STejun Heo { 738e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 739e22bee78STejun Heo unsigned int oflags = worker->flags; 740e22bee78STejun Heo 741cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 742cb444766STejun Heo 743d302f017STejun Heo worker->flags &= ~flags; 744e22bee78STejun Heo 745e22bee78STejun Heo /* if transitioning out of NOT_RUNNING, increment nr_running */ 746e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 747e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 748e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(gcwq->cpu)); 749d302f017STejun Heo } 750d302f017STejun Heo 751d302f017STejun Heo /** 752c8e55f36STejun Heo * busy_worker_head - return the busy hash head for a work 753c8e55f36STejun Heo * @gcwq: gcwq of interest 754c8e55f36STejun Heo * @work: work to be hashed 755c8e55f36STejun Heo * 756c8e55f36STejun Heo * Return hash head of @gcwq for @work. 757c8e55f36STejun Heo * 758c8e55f36STejun Heo * CONTEXT: 759c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 760c8e55f36STejun Heo * 761c8e55f36STejun Heo * RETURNS: 762c8e55f36STejun Heo * Pointer to the hash head. 763c8e55f36STejun Heo */ 764c8e55f36STejun Heo static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, 765c8e55f36STejun Heo struct work_struct *work) 766c8e55f36STejun Heo { 767c8e55f36STejun Heo const int base_shift = ilog2(sizeof(struct work_struct)); 768c8e55f36STejun Heo unsigned long v = (unsigned long)work; 769c8e55f36STejun Heo 770c8e55f36STejun Heo /* simple shift and fold hash, do we need something better? */ 771c8e55f36STejun Heo v >>= base_shift; 772c8e55f36STejun Heo v += v >> BUSY_WORKER_HASH_ORDER; 773c8e55f36STejun Heo v &= BUSY_WORKER_HASH_MASK; 774c8e55f36STejun Heo 775c8e55f36STejun Heo return &gcwq->busy_hash[v]; 776c8e55f36STejun Heo } 777c8e55f36STejun Heo 778c8e55f36STejun Heo /** 7798cca0eeaSTejun Heo * __find_worker_executing_work - find worker which is executing a work 7808cca0eeaSTejun Heo * @gcwq: gcwq of interest 7818cca0eeaSTejun Heo * @bwh: hash head as returned by busy_worker_head() 7828cca0eeaSTejun Heo * @work: work to find worker for 7838cca0eeaSTejun Heo * 7848cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. @bwh should be 7858cca0eeaSTejun Heo * the hash head obtained by calling busy_worker_head() with the same 7868cca0eeaSTejun Heo * work. 7878cca0eeaSTejun Heo * 7888cca0eeaSTejun Heo * CONTEXT: 7898cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 7908cca0eeaSTejun Heo * 7918cca0eeaSTejun Heo * RETURNS: 7928cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 7938cca0eeaSTejun Heo * otherwise. 7948cca0eeaSTejun Heo */ 7958cca0eeaSTejun Heo static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, 7968cca0eeaSTejun Heo struct hlist_head *bwh, 7978cca0eeaSTejun Heo struct work_struct *work) 7988cca0eeaSTejun Heo { 7998cca0eeaSTejun Heo struct worker *worker; 8008cca0eeaSTejun Heo struct hlist_node *tmp; 8018cca0eeaSTejun Heo 8028cca0eeaSTejun Heo hlist_for_each_entry(worker, tmp, bwh, hentry) 8038cca0eeaSTejun Heo if (worker->current_work == work) 8048cca0eeaSTejun Heo return worker; 8058cca0eeaSTejun Heo return NULL; 8068cca0eeaSTejun Heo } 8078cca0eeaSTejun Heo 8088cca0eeaSTejun Heo /** 8098cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 8108cca0eeaSTejun Heo * @gcwq: gcwq of interest 8118cca0eeaSTejun Heo * @work: work to find worker for 8128cca0eeaSTejun Heo * 8138cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. This function is 8148cca0eeaSTejun Heo * identical to __find_worker_executing_work() except that this 8158cca0eeaSTejun Heo * function calculates @bwh itself. 8168cca0eeaSTejun Heo * 8178cca0eeaSTejun Heo * CONTEXT: 8188cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8198cca0eeaSTejun Heo * 8208cca0eeaSTejun Heo * RETURNS: 8218cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8228cca0eeaSTejun Heo * otherwise. 8238cca0eeaSTejun Heo */ 8248cca0eeaSTejun Heo static struct worker *find_worker_executing_work(struct global_cwq *gcwq, 8258cca0eeaSTejun Heo struct work_struct *work) 8268cca0eeaSTejun Heo { 8278cca0eeaSTejun Heo return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), 8288cca0eeaSTejun Heo work); 8298cca0eeaSTejun Heo } 8308cca0eeaSTejun Heo 8318cca0eeaSTejun Heo /** 832649027d7STejun Heo * gcwq_determine_ins_pos - find insertion position 833649027d7STejun Heo * @gcwq: gcwq of interest 834649027d7STejun Heo * @cwq: cwq a work is being queued for 835649027d7STejun Heo * 836649027d7STejun Heo * A work for @cwq is about to be queued on @gcwq, determine insertion 837649027d7STejun Heo * position for the work. If @cwq is for HIGHPRI wq, the work is 838649027d7STejun Heo * queued at the head of the queue but in FIFO order with respect to 839649027d7STejun Heo * other HIGHPRI works; otherwise, at the end of the queue. This 840649027d7STejun Heo * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that 841649027d7STejun Heo * there are HIGHPRI works pending. 842649027d7STejun Heo * 843649027d7STejun Heo * CONTEXT: 844649027d7STejun Heo * spin_lock_irq(gcwq->lock). 845649027d7STejun Heo * 846649027d7STejun Heo * RETURNS: 847649027d7STejun Heo * Pointer to inserstion position. 848649027d7STejun Heo */ 849649027d7STejun Heo static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, 850649027d7STejun Heo struct cpu_workqueue_struct *cwq) 851649027d7STejun Heo { 852649027d7STejun Heo struct work_struct *twork; 853649027d7STejun Heo 854649027d7STejun Heo if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) 855649027d7STejun Heo return &gcwq->worklist; 856649027d7STejun Heo 857649027d7STejun Heo list_for_each_entry(twork, &gcwq->worklist, entry) { 858649027d7STejun Heo struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); 859649027d7STejun Heo 860649027d7STejun Heo if (!(tcwq->wq->flags & WQ_HIGHPRI)) 861649027d7STejun Heo break; 862649027d7STejun Heo } 863649027d7STejun Heo 864649027d7STejun Heo gcwq->flags |= GCWQ_HIGHPRI_PENDING; 865649027d7STejun Heo return &twork->entry; 866649027d7STejun Heo } 867649027d7STejun Heo 868649027d7STejun Heo /** 8697e11629dSTejun Heo * insert_work - insert a work into gcwq 8704690c4abSTejun Heo * @cwq: cwq @work belongs to 8714690c4abSTejun Heo * @work: work to insert 8724690c4abSTejun Heo * @head: insertion point 8734690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 8744690c4abSTejun Heo * 8757e11629dSTejun Heo * Insert @work which belongs to @cwq into @gcwq after @head. 8767e11629dSTejun Heo * @extra_flags is or'd to work_struct flags. 8774690c4abSTejun Heo * 8784690c4abSTejun Heo * CONTEXT: 8798b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 8804690c4abSTejun Heo */ 881b89deed3SOleg Nesterov static void insert_work(struct cpu_workqueue_struct *cwq, 8824690c4abSTejun Heo struct work_struct *work, struct list_head *head, 8834690c4abSTejun Heo unsigned int extra_flags) 884b89deed3SOleg Nesterov { 885e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 886e22bee78STejun Heo 8874690c4abSTejun Heo /* we own @work, set data and link */ 8887a22ad75STejun Heo set_work_cwq(work, cwq, extra_flags); 8894690c4abSTejun Heo 8906e84d644SOleg Nesterov /* 8916e84d644SOleg Nesterov * Ensure that we get the right work->data if we see the 8926e84d644SOleg Nesterov * result of list_add() below, see try_to_grab_pending(). 8936e84d644SOleg Nesterov */ 8946e84d644SOleg Nesterov smp_wmb(); 8954690c4abSTejun Heo 8961a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 897e22bee78STejun Heo 898e22bee78STejun Heo /* 899e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 900e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 901e22bee78STejun Heo * lying around lazily while there are works to be processed. 902e22bee78STejun Heo */ 903e22bee78STejun Heo smp_mb(); 904e22bee78STejun Heo 905649027d7STejun Heo if (__need_more_worker(gcwq)) 906e22bee78STejun Heo wake_up_worker(gcwq); 907b89deed3SOleg Nesterov } 908b89deed3SOleg Nesterov 9094690c4abSTejun Heo static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 9101da177e4SLinus Torvalds struct work_struct *work) 9111da177e4SLinus Torvalds { 912502ca9d8STejun Heo struct global_cwq *gcwq; 913502ca9d8STejun Heo struct cpu_workqueue_struct *cwq; 9141e19ffc6STejun Heo struct list_head *worklist; 9151da177e4SLinus Torvalds unsigned long flags; 9161da177e4SLinus Torvalds 917dc186ad7SThomas Gleixner debug_work_activate(work); 9181e19ffc6STejun Heo 919c7fc77f7STejun Heo /* determine gcwq to use */ 920c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 921c7fc77f7STejun Heo struct global_cwq *last_gcwq; 922c7fc77f7STejun Heo 923f3421797STejun Heo if (unlikely(cpu == WORK_CPU_UNBOUND)) 924f3421797STejun Heo cpu = raw_smp_processor_id(); 925f3421797STejun Heo 92618aa9effSTejun Heo /* 92718aa9effSTejun Heo * It's multi cpu. If @wq is non-reentrant and @work 92818aa9effSTejun Heo * was previously on a different cpu, it might still 92918aa9effSTejun Heo * be running there, in which case the work needs to 93018aa9effSTejun Heo * be queued on that cpu to guarantee non-reentrance. 93118aa9effSTejun Heo */ 932502ca9d8STejun Heo gcwq = get_gcwq(cpu); 93318aa9effSTejun Heo if (wq->flags & WQ_NON_REENTRANT && 93418aa9effSTejun Heo (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { 93518aa9effSTejun Heo struct worker *worker; 93618aa9effSTejun Heo 93718aa9effSTejun Heo spin_lock_irqsave(&last_gcwq->lock, flags); 93818aa9effSTejun Heo 93918aa9effSTejun Heo worker = find_worker_executing_work(last_gcwq, work); 94018aa9effSTejun Heo 94118aa9effSTejun Heo if (worker && worker->current_cwq->wq == wq) 94218aa9effSTejun Heo gcwq = last_gcwq; 94318aa9effSTejun Heo else { 94418aa9effSTejun Heo /* meh... not running there, queue here */ 94518aa9effSTejun Heo spin_unlock_irqrestore(&last_gcwq->lock, flags); 94618aa9effSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 94718aa9effSTejun Heo } 94818aa9effSTejun Heo } else 9498b03ae3cSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 950f3421797STejun Heo } else { 951f3421797STejun Heo gcwq = get_gcwq(WORK_CPU_UNBOUND); 952f3421797STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 953502ca9d8STejun Heo } 954502ca9d8STejun Heo 955502ca9d8STejun Heo /* gcwq determined, get cwq and queue */ 956502ca9d8STejun Heo cwq = get_cwq(gcwq->cpu, wq); 957502ca9d8STejun Heo 9584690c4abSTejun Heo BUG_ON(!list_empty(&work->entry)); 9591e19ffc6STejun Heo 96073f53c4aSTejun Heo cwq->nr_in_flight[cwq->work_color]++; 9611e19ffc6STejun Heo 9621e19ffc6STejun Heo if (likely(cwq->nr_active < cwq->max_active)) { 9631e19ffc6STejun Heo cwq->nr_active++; 964649027d7STejun Heo worklist = gcwq_determine_ins_pos(gcwq, cwq); 9651e19ffc6STejun Heo } else 9661e19ffc6STejun Heo worklist = &cwq->delayed_works; 9671e19ffc6STejun Heo 9681e19ffc6STejun Heo insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color)); 9691e19ffc6STejun Heo 9708b03ae3cSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 9711da177e4SLinus Torvalds } 9721da177e4SLinus Torvalds 9730fcb78c2SRolf Eike Beer /** 9740fcb78c2SRolf Eike Beer * queue_work - queue work on a workqueue 9750fcb78c2SRolf Eike Beer * @wq: workqueue to use 9760fcb78c2SRolf Eike Beer * @work: work to queue 9770fcb78c2SRolf Eike Beer * 978057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 9791da177e4SLinus Torvalds * 98000dfcaf7SOleg Nesterov * We queue the work to the CPU on which it was submitted, but if the CPU dies 98100dfcaf7SOleg Nesterov * it can be processed by another CPU. 9821da177e4SLinus Torvalds */ 9837ad5b3a5SHarvey Harrison int queue_work(struct workqueue_struct *wq, struct work_struct *work) 9841da177e4SLinus Torvalds { 985ef1ca236SOleg Nesterov int ret; 9861da177e4SLinus Torvalds 987ef1ca236SOleg Nesterov ret = queue_work_on(get_cpu(), wq, work); 988a848e3b6SOleg Nesterov put_cpu(); 989ef1ca236SOleg Nesterov 9901da177e4SLinus Torvalds return ret; 9911da177e4SLinus Torvalds } 992ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_work); 9931da177e4SLinus Torvalds 994c1a220e7SZhang Rui /** 995c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 996c1a220e7SZhang Rui * @cpu: CPU number to execute work on 997c1a220e7SZhang Rui * @wq: workqueue to use 998c1a220e7SZhang Rui * @work: work to queue 999c1a220e7SZhang Rui * 1000c1a220e7SZhang Rui * Returns 0 if @work was already on a queue, non-zero otherwise. 1001c1a220e7SZhang Rui * 1002c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1003c1a220e7SZhang Rui * can't go away. 1004c1a220e7SZhang Rui */ 1005c1a220e7SZhang Rui int 1006c1a220e7SZhang Rui queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) 1007c1a220e7SZhang Rui { 1008c1a220e7SZhang Rui int ret = 0; 1009c1a220e7SZhang Rui 101022df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 10114690c4abSTejun Heo __queue_work(cpu, wq, work); 1012c1a220e7SZhang Rui ret = 1; 1013c1a220e7SZhang Rui } 1014c1a220e7SZhang Rui return ret; 1015c1a220e7SZhang Rui } 1016c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1017c1a220e7SZhang Rui 10186d141c3fSLi Zefan static void delayed_work_timer_fn(unsigned long __data) 10191da177e4SLinus Torvalds { 102052bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 10217a22ad75STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); 10221da177e4SLinus Torvalds 10234690c4abSTejun Heo __queue_work(smp_processor_id(), cwq->wq, &dwork->work); 10241da177e4SLinus Torvalds } 10251da177e4SLinus Torvalds 10260fcb78c2SRolf Eike Beer /** 10270fcb78c2SRolf Eike Beer * queue_delayed_work - queue work on a workqueue after delay 10280fcb78c2SRolf Eike Beer * @wq: workqueue to use 1029af9997e4SRandy Dunlap * @dwork: delayable work to queue 10300fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10310fcb78c2SRolf Eike Beer * 1032057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10330fcb78c2SRolf Eike Beer */ 10347ad5b3a5SHarvey Harrison int queue_delayed_work(struct workqueue_struct *wq, 103552bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 10361da177e4SLinus Torvalds { 103752bad64dSDavid Howells if (delay == 0) 103863bc0362SOleg Nesterov return queue_work(wq, &dwork->work); 10391da177e4SLinus Torvalds 104063bc0362SOleg Nesterov return queue_delayed_work_on(-1, wq, dwork, delay); 10411da177e4SLinus Torvalds } 1042ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work); 10431da177e4SLinus Torvalds 10440fcb78c2SRolf Eike Beer /** 10450fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 10460fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 10470fcb78c2SRolf Eike Beer * @wq: workqueue to use 1048af9997e4SRandy Dunlap * @dwork: work to queue 10490fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10500fcb78c2SRolf Eike Beer * 1051057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10520fcb78c2SRolf Eike Beer */ 10537a6bc1cdSVenkatesh Pallipadi int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 105452bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 10557a6bc1cdSVenkatesh Pallipadi { 10567a6bc1cdSVenkatesh Pallipadi int ret = 0; 105752bad64dSDavid Howells struct timer_list *timer = &dwork->timer; 105852bad64dSDavid Howells struct work_struct *work = &dwork->work; 10597a6bc1cdSVenkatesh Pallipadi 106022df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 1061c7fc77f7STejun Heo unsigned int lcpu; 10627a22ad75STejun Heo 10637a6bc1cdSVenkatesh Pallipadi BUG_ON(timer_pending(timer)); 10647a6bc1cdSVenkatesh Pallipadi BUG_ON(!list_empty(&work->entry)); 10657a6bc1cdSVenkatesh Pallipadi 10668a3e77ccSAndrew Liu timer_stats_timer_set_start_info(&dwork->timer); 1067c7fc77f7STejun Heo 10687a22ad75STejun Heo /* 10697a22ad75STejun Heo * This stores cwq for the moment, for the timer_fn. 10707a22ad75STejun Heo * Note that the work's gcwq is preserved to allow 10717a22ad75STejun Heo * reentrance detection for delayed works. 10727a22ad75STejun Heo */ 1073c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1074c7fc77f7STejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 1075c7fc77f7STejun Heo 1076c7fc77f7STejun Heo if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) 1077c7fc77f7STejun Heo lcpu = gcwq->cpu; 1078c7fc77f7STejun Heo else 1079c7fc77f7STejun Heo lcpu = raw_smp_processor_id(); 1080c7fc77f7STejun Heo } else 1081c7fc77f7STejun Heo lcpu = WORK_CPU_UNBOUND; 1082c7fc77f7STejun Heo 10837a22ad75STejun Heo set_work_cwq(work, get_cwq(lcpu, wq), 0); 1084c7fc77f7STejun Heo 10857a6bc1cdSVenkatesh Pallipadi timer->expires = jiffies + delay; 108652bad64dSDavid Howells timer->data = (unsigned long)dwork; 10877a6bc1cdSVenkatesh Pallipadi timer->function = delayed_work_timer_fn; 108863bc0362SOleg Nesterov 108963bc0362SOleg Nesterov if (unlikely(cpu >= 0)) 10907a6bc1cdSVenkatesh Pallipadi add_timer_on(timer, cpu); 109163bc0362SOleg Nesterov else 109263bc0362SOleg Nesterov add_timer(timer); 10937a6bc1cdSVenkatesh Pallipadi ret = 1; 10947a6bc1cdSVenkatesh Pallipadi } 10957a6bc1cdSVenkatesh Pallipadi return ret; 10967a6bc1cdSVenkatesh Pallipadi } 1097ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 10981da177e4SLinus Torvalds 1099c8e55f36STejun Heo /** 1100c8e55f36STejun Heo * worker_enter_idle - enter idle state 1101c8e55f36STejun Heo * @worker: worker which is entering idle state 1102c8e55f36STejun Heo * 1103c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1104c8e55f36STejun Heo * necessary. 1105c8e55f36STejun Heo * 1106c8e55f36STejun Heo * LOCKING: 1107c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1108c8e55f36STejun Heo */ 1109c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 1110c8e55f36STejun Heo { 1111c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1112c8e55f36STejun Heo 1113c8e55f36STejun Heo BUG_ON(worker->flags & WORKER_IDLE); 1114c8e55f36STejun Heo BUG_ON(!list_empty(&worker->entry) && 1115c8e55f36STejun Heo (worker->hentry.next || worker->hentry.pprev)); 1116c8e55f36STejun Heo 1117cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1118cb444766STejun Heo worker->flags |= WORKER_IDLE; 1119c8e55f36STejun Heo gcwq->nr_idle++; 1120e22bee78STejun Heo worker->last_active = jiffies; 1121c8e55f36STejun Heo 1122c8e55f36STejun Heo /* idle_list is LIFO */ 1123c8e55f36STejun Heo list_add(&worker->entry, &gcwq->idle_list); 1124db7bccf4STejun Heo 1125e22bee78STejun Heo if (likely(!(worker->flags & WORKER_ROGUE))) { 1126e22bee78STejun Heo if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) 1127e22bee78STejun Heo mod_timer(&gcwq->idle_timer, 1128e22bee78STejun Heo jiffies + IDLE_WORKER_TIMEOUT); 1129e22bee78STejun Heo } else 1130db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 1131cb444766STejun Heo 1132cb444766STejun Heo /* sanity check nr_running */ 1133cb444766STejun Heo WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && 1134cb444766STejun Heo atomic_read(get_gcwq_nr_running(gcwq->cpu))); 1135c8e55f36STejun Heo } 1136c8e55f36STejun Heo 1137c8e55f36STejun Heo /** 1138c8e55f36STejun Heo * worker_leave_idle - leave idle state 1139c8e55f36STejun Heo * @worker: worker which is leaving idle state 1140c8e55f36STejun Heo * 1141c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1142c8e55f36STejun Heo * 1143c8e55f36STejun Heo * LOCKING: 1144c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1145c8e55f36STejun Heo */ 1146c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1147c8e55f36STejun Heo { 1148c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1149c8e55f36STejun Heo 1150c8e55f36STejun Heo BUG_ON(!(worker->flags & WORKER_IDLE)); 1151d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1152c8e55f36STejun Heo gcwq->nr_idle--; 1153c8e55f36STejun Heo list_del_init(&worker->entry); 1154c8e55f36STejun Heo } 1155c8e55f36STejun Heo 1156e22bee78STejun Heo /** 1157e22bee78STejun Heo * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq 1158e22bee78STejun Heo * @worker: self 1159e22bee78STejun Heo * 1160e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1161e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1162e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1163e22bee78STejun Heo * guaranteed to execute on the cpu. 1164e22bee78STejun Heo * 1165e22bee78STejun Heo * This function is to be used by rogue workers and rescuers to bind 1166e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1167e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1168e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1169e22bee78STejun Heo * verbatim as it's best effort and blocking and gcwq may be 1170e22bee78STejun Heo * [dis]associated in the meantime. 1171e22bee78STejun Heo * 1172e22bee78STejun Heo * This function tries set_cpus_allowed() and locks gcwq and verifies 1173e22bee78STejun Heo * the binding against GCWQ_DISASSOCIATED which is set during 1174e22bee78STejun Heo * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters 1175e22bee78STejun Heo * idle state or fetches works without dropping lock, it can guarantee 1176e22bee78STejun Heo * the scheduling requirement described in the first paragraph. 1177e22bee78STejun Heo * 1178e22bee78STejun Heo * CONTEXT: 1179e22bee78STejun Heo * Might sleep. Called without any lock but returns with gcwq->lock 1180e22bee78STejun Heo * held. 1181e22bee78STejun Heo * 1182e22bee78STejun Heo * RETURNS: 1183e22bee78STejun Heo * %true if the associated gcwq is online (@worker is successfully 1184e22bee78STejun Heo * bound), %false if offline. 1185e22bee78STejun Heo */ 1186e22bee78STejun Heo static bool worker_maybe_bind_and_lock(struct worker *worker) 1187e22bee78STejun Heo { 1188e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1189e22bee78STejun Heo struct task_struct *task = worker->task; 1190e22bee78STejun Heo 1191e22bee78STejun Heo while (true) { 1192e22bee78STejun Heo /* 1193e22bee78STejun Heo * The following call may fail, succeed or succeed 1194e22bee78STejun Heo * without actually migrating the task to the cpu if 1195e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 1196e22bee78STejun Heo * against GCWQ_DISASSOCIATED. 1197e22bee78STejun Heo */ 1198f3421797STejun Heo if (!(gcwq->flags & GCWQ_DISASSOCIATED)) 1199e22bee78STejun Heo set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); 1200e22bee78STejun Heo 1201e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1202e22bee78STejun Heo if (gcwq->flags & GCWQ_DISASSOCIATED) 1203e22bee78STejun Heo return false; 1204e22bee78STejun Heo if (task_cpu(task) == gcwq->cpu && 1205e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1206e22bee78STejun Heo get_cpu_mask(gcwq->cpu))) 1207e22bee78STejun Heo return true; 1208e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1209e22bee78STejun Heo 1210e22bee78STejun Heo /* CPU has come up inbetween, retry migration */ 1211e22bee78STejun Heo cpu_relax(); 1212e22bee78STejun Heo } 1213e22bee78STejun Heo } 1214e22bee78STejun Heo 1215e22bee78STejun Heo /* 1216e22bee78STejun Heo * Function for worker->rebind_work used to rebind rogue busy workers 1217e22bee78STejun Heo * to the associated cpu which is coming back online. This is 1218e22bee78STejun Heo * scheduled by cpu up but can race with other cpu hotplug operations 1219e22bee78STejun Heo * and may be executed twice without intervening cpu down. 1220e22bee78STejun Heo */ 1221e22bee78STejun Heo static void worker_rebind_fn(struct work_struct *work) 1222e22bee78STejun Heo { 1223e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1224e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1225e22bee78STejun Heo 1226e22bee78STejun Heo if (worker_maybe_bind_and_lock(worker)) 1227e22bee78STejun Heo worker_clr_flags(worker, WORKER_REBIND); 1228e22bee78STejun Heo 1229e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1230e22bee78STejun Heo } 1231e22bee78STejun Heo 1232c34056a3STejun Heo static struct worker *alloc_worker(void) 1233c34056a3STejun Heo { 1234c34056a3STejun Heo struct worker *worker; 1235c34056a3STejun Heo 1236c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1237c8e55f36STejun Heo if (worker) { 1238c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1239affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1240e22bee78STejun Heo INIT_WORK(&worker->rebind_work, worker_rebind_fn); 1241e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1242e22bee78STejun Heo worker->flags = WORKER_PREP; 1243c8e55f36STejun Heo } 1244c34056a3STejun Heo return worker; 1245c34056a3STejun Heo } 1246c34056a3STejun Heo 1247c34056a3STejun Heo /** 1248c34056a3STejun Heo * create_worker - create a new workqueue worker 12497e11629dSTejun Heo * @gcwq: gcwq the new worker will belong to 1250c34056a3STejun Heo * @bind: whether to set affinity to @cpu or not 1251c34056a3STejun Heo * 12527e11629dSTejun Heo * Create a new worker which is bound to @gcwq. The returned worker 1253c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1254c34056a3STejun Heo * destroy_worker(). 1255c34056a3STejun Heo * 1256c34056a3STejun Heo * CONTEXT: 1257c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1258c34056a3STejun Heo * 1259c34056a3STejun Heo * RETURNS: 1260c34056a3STejun Heo * Pointer to the newly created worker. 1261c34056a3STejun Heo */ 12627e11629dSTejun Heo static struct worker *create_worker(struct global_cwq *gcwq, bool bind) 1263c34056a3STejun Heo { 1264f3421797STejun Heo bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; 1265c34056a3STejun Heo struct worker *worker = NULL; 1266f3421797STejun Heo int id = -1; 1267c34056a3STejun Heo 12688b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 12698b03ae3cSTejun Heo while (ida_get_new(&gcwq->worker_ida, &id)) { 12708b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 12718b03ae3cSTejun Heo if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) 1272c34056a3STejun Heo goto fail; 12738b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1274c34056a3STejun Heo } 12758b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1276c34056a3STejun Heo 1277c34056a3STejun Heo worker = alloc_worker(); 1278c34056a3STejun Heo if (!worker) 1279c34056a3STejun Heo goto fail; 1280c34056a3STejun Heo 12818b03ae3cSTejun Heo worker->gcwq = gcwq; 1282c34056a3STejun Heo worker->id = id; 1283c34056a3STejun Heo 1284f3421797STejun Heo if (!on_unbound_cpu) 1285f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1286f3421797STejun Heo "kworker/%u:%d", gcwq->cpu, id); 1287f3421797STejun Heo else 1288f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1289f3421797STejun Heo "kworker/u:%d", id); 1290c34056a3STejun Heo if (IS_ERR(worker->task)) 1291c34056a3STejun Heo goto fail; 1292c34056a3STejun Heo 1293db7bccf4STejun Heo /* 1294db7bccf4STejun Heo * A rogue worker will become a regular one if CPU comes 1295db7bccf4STejun Heo * online later on. Make sure every worker has 1296db7bccf4STejun Heo * PF_THREAD_BOUND set. 1297db7bccf4STejun Heo */ 1298f3421797STejun Heo if (bind && !on_unbound_cpu) 12998b03ae3cSTejun Heo kthread_bind(worker->task, gcwq->cpu); 1300f3421797STejun Heo else { 1301db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1302f3421797STejun Heo if (on_unbound_cpu) 1303f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1304f3421797STejun Heo } 1305c34056a3STejun Heo 1306c34056a3STejun Heo return worker; 1307c34056a3STejun Heo fail: 1308c34056a3STejun Heo if (id >= 0) { 13098b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13108b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 13118b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1312c34056a3STejun Heo } 1313c34056a3STejun Heo kfree(worker); 1314c34056a3STejun Heo return NULL; 1315c34056a3STejun Heo } 1316c34056a3STejun Heo 1317c34056a3STejun Heo /** 1318c34056a3STejun Heo * start_worker - start a newly created worker 1319c34056a3STejun Heo * @worker: worker to start 1320c34056a3STejun Heo * 1321c8e55f36STejun Heo * Make the gcwq aware of @worker and start it. 1322c34056a3STejun Heo * 1323c34056a3STejun Heo * CONTEXT: 13248b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1325c34056a3STejun Heo */ 1326c34056a3STejun Heo static void start_worker(struct worker *worker) 1327c34056a3STejun Heo { 1328cb444766STejun Heo worker->flags |= WORKER_STARTED; 1329c8e55f36STejun Heo worker->gcwq->nr_workers++; 1330c8e55f36STejun Heo worker_enter_idle(worker); 1331c34056a3STejun Heo wake_up_process(worker->task); 1332c34056a3STejun Heo } 1333c34056a3STejun Heo 1334c34056a3STejun Heo /** 1335c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1336c34056a3STejun Heo * @worker: worker to be destroyed 1337c34056a3STejun Heo * 1338c8e55f36STejun Heo * Destroy @worker and adjust @gcwq stats accordingly. 1339c8e55f36STejun Heo * 1340c8e55f36STejun Heo * CONTEXT: 1341c8e55f36STejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1342c34056a3STejun Heo */ 1343c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1344c34056a3STejun Heo { 13458b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 1346c34056a3STejun Heo int id = worker->id; 1347c34056a3STejun Heo 1348c34056a3STejun Heo /* sanity check frenzy */ 1349c34056a3STejun Heo BUG_ON(worker->current_work); 1350affee4b2STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1351c34056a3STejun Heo 1352c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1353c8e55f36STejun Heo gcwq->nr_workers--; 1354c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1355c8e55f36STejun Heo gcwq->nr_idle--; 1356c8e55f36STejun Heo 1357c8e55f36STejun Heo list_del_init(&worker->entry); 1358cb444766STejun Heo worker->flags |= WORKER_DIE; 1359c8e55f36STejun Heo 1360c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1361c8e55f36STejun Heo 1362c34056a3STejun Heo kthread_stop(worker->task); 1363c34056a3STejun Heo kfree(worker); 1364c34056a3STejun Heo 13658b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13668b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 1367c34056a3STejun Heo } 1368c34056a3STejun Heo 1369e22bee78STejun Heo static void idle_worker_timeout(unsigned long __gcwq) 1370e22bee78STejun Heo { 1371e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1372e22bee78STejun Heo 1373e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1374e22bee78STejun Heo 1375e22bee78STejun Heo if (too_many_workers(gcwq)) { 1376e22bee78STejun Heo struct worker *worker; 1377e22bee78STejun Heo unsigned long expires; 1378e22bee78STejun Heo 1379e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 1380e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1381e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1382e22bee78STejun Heo 1383e22bee78STejun Heo if (time_before(jiffies, expires)) 1384e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1385e22bee78STejun Heo else { 1386e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 1387e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 1388e22bee78STejun Heo wake_up_worker(gcwq); 1389e22bee78STejun Heo } 1390e22bee78STejun Heo } 1391e22bee78STejun Heo 1392e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1393e22bee78STejun Heo } 1394e22bee78STejun Heo 1395e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1396e22bee78STejun Heo { 1397e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1398e22bee78STejun Heo struct workqueue_struct *wq = cwq->wq; 1399f3421797STejun Heo unsigned int cpu; 1400e22bee78STejun Heo 1401e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1402e22bee78STejun Heo return false; 1403e22bee78STejun Heo 1404e22bee78STejun Heo /* mayday mayday mayday */ 1405f3421797STejun Heo cpu = cwq->gcwq->cpu; 1406f3421797STejun Heo /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1407f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 1408f3421797STejun Heo cpu = 0; 1409f2e005aaSTejun Heo if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) 1410e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1411e22bee78STejun Heo return true; 1412e22bee78STejun Heo } 1413e22bee78STejun Heo 1414e22bee78STejun Heo static void gcwq_mayday_timeout(unsigned long __gcwq) 1415e22bee78STejun Heo { 1416e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1417e22bee78STejun Heo struct work_struct *work; 1418e22bee78STejun Heo 1419e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1420e22bee78STejun Heo 1421e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 1422e22bee78STejun Heo /* 1423e22bee78STejun Heo * We've been trying to create a new worker but 1424e22bee78STejun Heo * haven't been successful. We might be hitting an 1425e22bee78STejun Heo * allocation deadlock. Send distress signals to 1426e22bee78STejun Heo * rescuers. 1427e22bee78STejun Heo */ 1428e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) 1429e22bee78STejun Heo send_mayday(work); 1430e22bee78STejun Heo } 1431e22bee78STejun Heo 1432e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1433e22bee78STejun Heo 1434e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); 1435e22bee78STejun Heo } 1436e22bee78STejun Heo 1437e22bee78STejun Heo /** 1438e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 1439e22bee78STejun Heo * @gcwq: gcwq to create a new worker for 1440e22bee78STejun Heo * 1441e22bee78STejun Heo * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to 1442e22bee78STejun Heo * have at least one idle worker on return from this function. If 1443e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 1444e22bee78STejun Heo * sent to all rescuers with works scheduled on @gcwq to resolve 1445e22bee78STejun Heo * possible allocation deadlock. 1446e22bee78STejun Heo * 1447e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1448e22bee78STejun Heo * may_start_working() true. 1449e22bee78STejun Heo * 1450e22bee78STejun Heo * LOCKING: 1451e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1452e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1453e22bee78STejun Heo * manager. 1454e22bee78STejun Heo * 1455e22bee78STejun Heo * RETURNS: 1456e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1457e22bee78STejun Heo * otherwise. 1458e22bee78STejun Heo */ 1459e22bee78STejun Heo static bool maybe_create_worker(struct global_cwq *gcwq) 1460e22bee78STejun Heo { 1461e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1462e22bee78STejun Heo return false; 1463e22bee78STejun Heo restart: 14649f9c2364STejun Heo spin_unlock_irq(&gcwq->lock); 14659f9c2364STejun Heo 1466e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 1467e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1468e22bee78STejun Heo 1469e22bee78STejun Heo while (true) { 1470e22bee78STejun Heo struct worker *worker; 1471e22bee78STejun Heo 1472e22bee78STejun Heo worker = create_worker(gcwq, true); 1473e22bee78STejun Heo if (worker) { 1474e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1475e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1476e22bee78STejun Heo start_worker(worker); 1477e22bee78STejun Heo BUG_ON(need_to_create_worker(gcwq)); 1478e22bee78STejun Heo return true; 1479e22bee78STejun Heo } 1480e22bee78STejun Heo 1481e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1482e22bee78STejun Heo break; 1483e22bee78STejun Heo 1484e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1485e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 14869f9c2364STejun Heo 1487e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1488e22bee78STejun Heo break; 1489e22bee78STejun Heo } 1490e22bee78STejun Heo 1491e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1492e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1493e22bee78STejun Heo if (need_to_create_worker(gcwq)) 1494e22bee78STejun Heo goto restart; 1495e22bee78STejun Heo return true; 1496e22bee78STejun Heo } 1497e22bee78STejun Heo 1498e22bee78STejun Heo /** 1499e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 1500e22bee78STejun Heo * @gcwq: gcwq to destroy workers for 1501e22bee78STejun Heo * 1502e22bee78STejun Heo * Destroy @gcwq workers which have been idle for longer than 1503e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1504e22bee78STejun Heo * 1505e22bee78STejun Heo * LOCKING: 1506e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1507e22bee78STejun Heo * multiple times. Called only from manager. 1508e22bee78STejun Heo * 1509e22bee78STejun Heo * RETURNS: 1510e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1511e22bee78STejun Heo * otherwise. 1512e22bee78STejun Heo */ 1513e22bee78STejun Heo static bool maybe_destroy_workers(struct global_cwq *gcwq) 1514e22bee78STejun Heo { 1515e22bee78STejun Heo bool ret = false; 1516e22bee78STejun Heo 1517e22bee78STejun Heo while (too_many_workers(gcwq)) { 1518e22bee78STejun Heo struct worker *worker; 1519e22bee78STejun Heo unsigned long expires; 1520e22bee78STejun Heo 1521e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1522e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1523e22bee78STejun Heo 1524e22bee78STejun Heo if (time_before(jiffies, expires)) { 1525e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1526e22bee78STejun Heo break; 1527e22bee78STejun Heo } 1528e22bee78STejun Heo 1529e22bee78STejun Heo destroy_worker(worker); 1530e22bee78STejun Heo ret = true; 1531e22bee78STejun Heo } 1532e22bee78STejun Heo 1533e22bee78STejun Heo return ret; 1534e22bee78STejun Heo } 1535e22bee78STejun Heo 1536e22bee78STejun Heo /** 1537e22bee78STejun Heo * manage_workers - manage worker pool 1538e22bee78STejun Heo * @worker: self 1539e22bee78STejun Heo * 1540e22bee78STejun Heo * Assume the manager role and manage gcwq worker pool @worker belongs 1541e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 1542e22bee78STejun Heo * gcwq. The exclusion is handled automatically by this function. 1543e22bee78STejun Heo * 1544e22bee78STejun Heo * The caller can safely start processing works on false return. On 1545e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 1546e22bee78STejun Heo * and may_start_working() is true. 1547e22bee78STejun Heo * 1548e22bee78STejun Heo * CONTEXT: 1549e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1550e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 1551e22bee78STejun Heo * 1552e22bee78STejun Heo * RETURNS: 1553e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true if 1554e22bee78STejun Heo * some action was taken. 1555e22bee78STejun Heo */ 1556e22bee78STejun Heo static bool manage_workers(struct worker *worker) 1557e22bee78STejun Heo { 1558e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1559e22bee78STejun Heo bool ret = false; 1560e22bee78STejun Heo 1561e22bee78STejun Heo if (gcwq->flags & GCWQ_MANAGING_WORKERS) 1562e22bee78STejun Heo return ret; 1563e22bee78STejun Heo 1564e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGE_WORKERS; 1565e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 1566e22bee78STejun Heo 1567e22bee78STejun Heo /* 1568e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 1569e22bee78STejun Heo * on return. 1570e22bee78STejun Heo */ 1571e22bee78STejun Heo ret |= maybe_destroy_workers(gcwq); 1572e22bee78STejun Heo ret |= maybe_create_worker(gcwq); 1573e22bee78STejun Heo 1574e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 1575e22bee78STejun Heo 1576e22bee78STejun Heo /* 1577e22bee78STejun Heo * The trustee might be waiting to take over the manager 1578e22bee78STejun Heo * position, tell it we're done. 1579e22bee78STejun Heo */ 1580e22bee78STejun Heo if (unlikely(gcwq->trustee)) 1581e22bee78STejun Heo wake_up_all(&gcwq->trustee_wait); 1582e22bee78STejun Heo 1583e22bee78STejun Heo return ret; 1584e22bee78STejun Heo } 1585e22bee78STejun Heo 1586a62428c0STejun Heo /** 1587affee4b2STejun Heo * move_linked_works - move linked works to a list 1588affee4b2STejun Heo * @work: start of series of works to be scheduled 1589affee4b2STejun Heo * @head: target list to append @work to 1590affee4b2STejun Heo * @nextp: out paramter for nested worklist walking 1591affee4b2STejun Heo * 1592affee4b2STejun Heo * Schedule linked works starting from @work to @head. Work series to 1593affee4b2STejun Heo * be scheduled starts at @work and includes any consecutive work with 1594affee4b2STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 1595affee4b2STejun Heo * 1596affee4b2STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 1597affee4b2STejun Heo * the last scheduled work. This allows move_linked_works() to be 1598affee4b2STejun Heo * nested inside outer list_for_each_entry_safe(). 1599affee4b2STejun Heo * 1600affee4b2STejun Heo * CONTEXT: 16018b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1602affee4b2STejun Heo */ 1603affee4b2STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1604affee4b2STejun Heo struct work_struct **nextp) 1605affee4b2STejun Heo { 1606affee4b2STejun Heo struct work_struct *n; 1607affee4b2STejun Heo 1608affee4b2STejun Heo /* 1609affee4b2STejun Heo * Linked worklist will always end before the end of the list, 1610affee4b2STejun Heo * use NULL for list head. 1611affee4b2STejun Heo */ 1612affee4b2STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1613affee4b2STejun Heo list_move_tail(&work->entry, head); 1614affee4b2STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1615affee4b2STejun Heo break; 1616affee4b2STejun Heo } 1617affee4b2STejun Heo 1618affee4b2STejun Heo /* 1619affee4b2STejun Heo * If we're already inside safe list traversal and have moved 1620affee4b2STejun Heo * multiple works to the scheduled queue, the next position 1621affee4b2STejun Heo * needs to be updated. 1622affee4b2STejun Heo */ 1623affee4b2STejun Heo if (nextp) 1624affee4b2STejun Heo *nextp = n; 1625affee4b2STejun Heo } 1626affee4b2STejun Heo 16271e19ffc6STejun Heo static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) 16281e19ffc6STejun Heo { 16291e19ffc6STejun Heo struct work_struct *work = list_first_entry(&cwq->delayed_works, 16301e19ffc6STejun Heo struct work_struct, entry); 1631649027d7STejun Heo struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); 16321e19ffc6STejun Heo 1633649027d7STejun Heo move_linked_works(work, pos, NULL); 16341e19ffc6STejun Heo cwq->nr_active++; 16351e19ffc6STejun Heo } 16361e19ffc6STejun Heo 1637affee4b2STejun Heo /** 163873f53c4aSTejun Heo * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight 163973f53c4aSTejun Heo * @cwq: cwq of interest 164073f53c4aSTejun Heo * @color: color of work which left the queue 164173f53c4aSTejun Heo * 164273f53c4aSTejun Heo * A work either has completed or is removed from pending queue, 164373f53c4aSTejun Heo * decrement nr_in_flight of its cwq and handle workqueue flushing. 164473f53c4aSTejun Heo * 164573f53c4aSTejun Heo * CONTEXT: 16468b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 164773f53c4aSTejun Heo */ 164873f53c4aSTejun Heo static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) 164973f53c4aSTejun Heo { 165073f53c4aSTejun Heo /* ignore uncolored works */ 165173f53c4aSTejun Heo if (color == WORK_NO_COLOR) 165273f53c4aSTejun Heo return; 165373f53c4aSTejun Heo 165473f53c4aSTejun Heo cwq->nr_in_flight[color]--; 16551e19ffc6STejun Heo cwq->nr_active--; 16561e19ffc6STejun Heo 1657502ca9d8STejun Heo if (!list_empty(&cwq->delayed_works)) { 16581e19ffc6STejun Heo /* one down, submit a delayed one */ 1659502ca9d8STejun Heo if (cwq->nr_active < cwq->max_active) 16601e19ffc6STejun Heo cwq_activate_first_delayed(cwq); 1661502ca9d8STejun Heo } 166273f53c4aSTejun Heo 166373f53c4aSTejun Heo /* is flush in progress and are we at the flushing tip? */ 166473f53c4aSTejun Heo if (likely(cwq->flush_color != color)) 166573f53c4aSTejun Heo return; 166673f53c4aSTejun Heo 166773f53c4aSTejun Heo /* are there still in-flight works? */ 166873f53c4aSTejun Heo if (cwq->nr_in_flight[color]) 166973f53c4aSTejun Heo return; 167073f53c4aSTejun Heo 167173f53c4aSTejun Heo /* this cwq is done, clear flush_color */ 167273f53c4aSTejun Heo cwq->flush_color = -1; 167373f53c4aSTejun Heo 167473f53c4aSTejun Heo /* 167573f53c4aSTejun Heo * If this was the last cwq, wake up the first flusher. It 167673f53c4aSTejun Heo * will handle the rest. 167773f53c4aSTejun Heo */ 167873f53c4aSTejun Heo if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) 167973f53c4aSTejun Heo complete(&cwq->wq->first_flusher->done); 168073f53c4aSTejun Heo } 168173f53c4aSTejun Heo 168273f53c4aSTejun Heo /** 1683a62428c0STejun Heo * process_one_work - process single work 1684c34056a3STejun Heo * @worker: self 1685a62428c0STejun Heo * @work: work to process 1686a62428c0STejun Heo * 1687a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 1688a62428c0STejun Heo * process a single work including synchronization against and 1689a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 1690a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 1691a62428c0STejun Heo * call this function to process a work. 1692a62428c0STejun Heo * 1693a62428c0STejun Heo * CONTEXT: 16948b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1695a62428c0STejun Heo */ 1696c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 16971da177e4SLinus Torvalds { 16987e11629dSTejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 16998b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 1700c8e55f36STejun Heo struct hlist_head *bwh = busy_worker_head(gcwq, work); 1701fb0e7bebSTejun Heo bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 17026bb49e59SDavid Howells work_func_t f = work->func; 170373f53c4aSTejun Heo int work_color; 17047e11629dSTejun Heo struct worker *collision; 17054e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 17064e6045f1SJohannes Berg /* 1707a62428c0STejun Heo * It is permissible to free the struct work_struct from 1708a62428c0STejun Heo * inside the function that is called from it, this we need to 1709a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 1710a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 1711a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 17124e6045f1SJohannes Berg */ 17134e6045f1SJohannes Berg struct lockdep_map lockdep_map = work->lockdep_map; 17144e6045f1SJohannes Berg #endif 17157e11629dSTejun Heo /* 17167e11629dSTejun Heo * A single work shouldn't be executed concurrently by 17177e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 17187e11629dSTejun Heo * already processing the work. If so, defer the work to the 17197e11629dSTejun Heo * currently executing one. 17207e11629dSTejun Heo */ 17217e11629dSTejun Heo collision = __find_worker_executing_work(gcwq, bwh, work); 17227e11629dSTejun Heo if (unlikely(collision)) { 17237e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 17247e11629dSTejun Heo return; 17257e11629dSTejun Heo } 17267e11629dSTejun Heo 1727a62428c0STejun Heo /* claim and process */ 1728dc186ad7SThomas Gleixner debug_work_deactivate(work); 1729c8e55f36STejun Heo hlist_add_head(&worker->hentry, bwh); 1730c34056a3STejun Heo worker->current_work = work; 17318cca0eeaSTejun Heo worker->current_cwq = cwq; 173273f53c4aSTejun Heo work_color = get_work_color(work); 17337a22ad75STejun Heo 17347a22ad75STejun Heo /* record the current cpu number in the work data and dequeue */ 17357a22ad75STejun Heo set_work_cpu(work, gcwq->cpu); 1736a62428c0STejun Heo list_del_init(&work->entry); 1737a62428c0STejun Heo 1738649027d7STejun Heo /* 1739649027d7STejun Heo * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, 1740649027d7STejun Heo * wake up another worker; otherwise, clear HIGHPRI_PENDING. 1741649027d7STejun Heo */ 1742649027d7STejun Heo if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { 1743649027d7STejun Heo struct work_struct *nwork = list_first_entry(&gcwq->worklist, 1744649027d7STejun Heo struct work_struct, entry); 1745649027d7STejun Heo 1746649027d7STejun Heo if (!list_empty(&gcwq->worklist) && 1747649027d7STejun Heo get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) 1748649027d7STejun Heo wake_up_worker(gcwq); 1749649027d7STejun Heo else 1750649027d7STejun Heo gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; 1751649027d7STejun Heo } 1752649027d7STejun Heo 1753fb0e7bebSTejun Heo /* 1754fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 1755fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 1756fb0e7bebSTejun Heo */ 1757fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1758fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 1759fb0e7bebSTejun Heo 17608b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 17611da177e4SLinus Torvalds 176223b2e599SOleg Nesterov work_clear_pending(work); 17633295f0efSIngo Molnar lock_map_acquire(&cwq->wq->lockdep_map); 17643295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 176565f27f38SDavid Howells f(work); 17663295f0efSIngo Molnar lock_map_release(&lockdep_map); 17673295f0efSIngo Molnar lock_map_release(&cwq->wq->lockdep_map); 17681da177e4SLinus Torvalds 1769d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 1770d5abe669SPeter Zijlstra printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " 1771d5abe669SPeter Zijlstra "%s/0x%08x/%d\n", 1772a62428c0STejun Heo current->comm, preempt_count(), task_pid_nr(current)); 1773d5abe669SPeter Zijlstra printk(KERN_ERR " last function: "); 1774d5abe669SPeter Zijlstra print_symbol("%s\n", (unsigned long)f); 1775d5abe669SPeter Zijlstra debug_show_held_locks(current); 1776d5abe669SPeter Zijlstra dump_stack(); 1777d5abe669SPeter Zijlstra } 1778d5abe669SPeter Zijlstra 17798b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1780a62428c0STejun Heo 1781fb0e7bebSTejun Heo /* clear cpu intensive status */ 1782fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1783fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 1784fb0e7bebSTejun Heo 1785a62428c0STejun Heo /* we're done with it, release */ 1786c8e55f36STejun Heo hlist_del_init(&worker->hentry); 1787c34056a3STejun Heo worker->current_work = NULL; 17888cca0eeaSTejun Heo worker->current_cwq = NULL; 178973f53c4aSTejun Heo cwq_dec_nr_in_flight(cwq, work_color); 17901da177e4SLinus Torvalds } 1791a62428c0STejun Heo 1792affee4b2STejun Heo /** 1793affee4b2STejun Heo * process_scheduled_works - process scheduled works 1794affee4b2STejun Heo * @worker: self 1795affee4b2STejun Heo * 1796affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 1797affee4b2STejun Heo * may change while processing a work, so this function repeatedly 1798affee4b2STejun Heo * fetches a work from the top and executes it. 1799affee4b2STejun Heo * 1800affee4b2STejun Heo * CONTEXT: 18018b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1802affee4b2STejun Heo * multiple times. 1803affee4b2STejun Heo */ 1804affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 1805a62428c0STejun Heo { 1806affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 1807affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 1808a62428c0STejun Heo struct work_struct, entry); 1809c34056a3STejun Heo process_one_work(worker, work); 1810a62428c0STejun Heo } 18111da177e4SLinus Torvalds } 18121da177e4SLinus Torvalds 18134690c4abSTejun Heo /** 18144690c4abSTejun Heo * worker_thread - the worker thread function 1815c34056a3STejun Heo * @__worker: self 18164690c4abSTejun Heo * 1817e22bee78STejun Heo * The gcwq worker thread function. There's a single dynamic pool of 1818e22bee78STejun Heo * these per each cpu. These workers process all works regardless of 1819e22bee78STejun Heo * their specific target workqueue. The only exception is works which 1820e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 1821e22bee78STejun Heo * rescuer_thread(). 18224690c4abSTejun Heo */ 1823c34056a3STejun Heo static int worker_thread(void *__worker) 18241da177e4SLinus Torvalds { 1825c34056a3STejun Heo struct worker *worker = __worker; 18268b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 18271da177e4SLinus Torvalds 1828e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 1829e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 1830c8e55f36STejun Heo woke_up: 18318b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1832affee4b2STejun Heo 1833c8e55f36STejun Heo /* DIE can be set only while we're idle, checking here is enough */ 1834c8e55f36STejun Heo if (worker->flags & WORKER_DIE) { 1835c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1836e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 1837c8e55f36STejun Heo return 0; 1838c8e55f36STejun Heo } 1839c8e55f36STejun Heo 1840c8e55f36STejun Heo worker_leave_idle(worker); 1841db7bccf4STejun Heo recheck: 1842e22bee78STejun Heo /* no more worker necessary? */ 1843e22bee78STejun Heo if (!need_more_worker(gcwq)) 1844e22bee78STejun Heo goto sleep; 1845e22bee78STejun Heo 1846e22bee78STejun Heo /* do we need to manage? */ 1847e22bee78STejun Heo if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) 1848e22bee78STejun Heo goto recheck; 1849e22bee78STejun Heo 1850c8e55f36STejun Heo /* 1851c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 1852c8e55f36STejun Heo * preparing to process a work or actually processing it. 1853c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 1854c8e55f36STejun Heo */ 1855c8e55f36STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1856c8e55f36STejun Heo 1857e22bee78STejun Heo /* 1858e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 1859e22bee78STejun Heo * at least one idle worker or that someone else has already 1860e22bee78STejun Heo * assumed the manager role. 1861e22bee78STejun Heo */ 1862e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 1863e22bee78STejun Heo 1864e22bee78STejun Heo do { 1865affee4b2STejun Heo struct work_struct *work = 18667e11629dSTejun Heo list_first_entry(&gcwq->worklist, 1867affee4b2STejun Heo struct work_struct, entry); 1868affee4b2STejun Heo 1869c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 1870affee4b2STejun Heo /* optimization path, not strictly necessary */ 1871affee4b2STejun Heo process_one_work(worker, work); 1872affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 1873affee4b2STejun Heo process_scheduled_works(worker); 1874affee4b2STejun Heo } else { 1875c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 1876affee4b2STejun Heo process_scheduled_works(worker); 1877affee4b2STejun Heo } 1878e22bee78STejun Heo } while (keep_working(gcwq)); 1879affee4b2STejun Heo 1880e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 1881d313dd85STejun Heo sleep: 1882e22bee78STejun Heo if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) 1883e22bee78STejun Heo goto recheck; 1884d313dd85STejun Heo 1885c8e55f36STejun Heo /* 1886e22bee78STejun Heo * gcwq->lock is held and there's no work to process and no 1887e22bee78STejun Heo * need to manage, sleep. Workers are woken up only while 1888e22bee78STejun Heo * holding gcwq->lock or from local cpu, so setting the 1889e22bee78STejun Heo * current state before releasing gcwq->lock is enough to 1890e22bee78STejun Heo * prevent losing any event. 1891c8e55f36STejun Heo */ 1892c8e55f36STejun Heo worker_enter_idle(worker); 1893c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 18948b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1895c8e55f36STejun Heo schedule(); 1896c8e55f36STejun Heo goto woke_up; 18971da177e4SLinus Torvalds } 18981da177e4SLinus Torvalds 1899e22bee78STejun Heo /** 1900e22bee78STejun Heo * rescuer_thread - the rescuer thread function 1901e22bee78STejun Heo * @__wq: the associated workqueue 1902e22bee78STejun Heo * 1903e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 1904e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 1905e22bee78STejun Heo * 1906e22bee78STejun Heo * Regular work processing on a gcwq may block trying to create a new 1907e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 1908e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 1909e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 1910e22bee78STejun Heo * the problem rescuer solves. 1911e22bee78STejun Heo * 1912e22bee78STejun Heo * When such condition is possible, the gcwq summons rescuers of all 1913e22bee78STejun Heo * workqueues which have works queued on the gcwq and let them process 1914e22bee78STejun Heo * those works so that forward progress can be guaranteed. 1915e22bee78STejun Heo * 1916e22bee78STejun Heo * This should happen rarely. 1917e22bee78STejun Heo */ 1918e22bee78STejun Heo static int rescuer_thread(void *__wq) 1919e22bee78STejun Heo { 1920e22bee78STejun Heo struct workqueue_struct *wq = __wq; 1921e22bee78STejun Heo struct worker *rescuer = wq->rescuer; 1922e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 1923f3421797STejun Heo bool is_unbound = wq->flags & WQ_UNBOUND; 1924e22bee78STejun Heo unsigned int cpu; 1925e22bee78STejun Heo 1926e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 1927e22bee78STejun Heo repeat: 1928e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 1929e22bee78STejun Heo 1930e22bee78STejun Heo if (kthread_should_stop()) 1931e22bee78STejun Heo return 0; 1932e22bee78STejun Heo 1933f3421797STejun Heo /* 1934f3421797STejun Heo * See whether any cpu is asking for help. Unbounded 1935f3421797STejun Heo * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. 1936f3421797STejun Heo */ 1937f2e005aaSTejun Heo for_each_mayday_cpu(cpu, wq->mayday_mask) { 1938f3421797STejun Heo unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 1939f3421797STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); 1940e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 1941e22bee78STejun Heo struct work_struct *work, *n; 1942e22bee78STejun Heo 1943e22bee78STejun Heo __set_current_state(TASK_RUNNING); 1944f2e005aaSTejun Heo mayday_clear_cpu(cpu, wq->mayday_mask); 1945e22bee78STejun Heo 1946e22bee78STejun Heo /* migrate to the target cpu if possible */ 1947e22bee78STejun Heo rescuer->gcwq = gcwq; 1948e22bee78STejun Heo worker_maybe_bind_and_lock(rescuer); 1949e22bee78STejun Heo 1950e22bee78STejun Heo /* 1951e22bee78STejun Heo * Slurp in all works issued via this workqueue and 1952e22bee78STejun Heo * process'em. 1953e22bee78STejun Heo */ 1954e22bee78STejun Heo BUG_ON(!list_empty(&rescuer->scheduled)); 1955e22bee78STejun Heo list_for_each_entry_safe(work, n, &gcwq->worklist, entry) 1956e22bee78STejun Heo if (get_work_cwq(work) == cwq) 1957e22bee78STejun Heo move_linked_works(work, scheduled, &n); 1958e22bee78STejun Heo 1959e22bee78STejun Heo process_scheduled_works(rescuer); 1960e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1961e22bee78STejun Heo } 1962e22bee78STejun Heo 1963e22bee78STejun Heo schedule(); 1964e22bee78STejun Heo goto repeat; 1965e22bee78STejun Heo } 1966e22bee78STejun Heo 1967fc2e4d70SOleg Nesterov struct wq_barrier { 1968fc2e4d70SOleg Nesterov struct work_struct work; 1969fc2e4d70SOleg Nesterov struct completion done; 1970fc2e4d70SOleg Nesterov }; 1971fc2e4d70SOleg Nesterov 1972fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 1973fc2e4d70SOleg Nesterov { 1974fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 1975fc2e4d70SOleg Nesterov complete(&barr->done); 1976fc2e4d70SOleg Nesterov } 1977fc2e4d70SOleg Nesterov 19784690c4abSTejun Heo /** 19794690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 19804690c4abSTejun Heo * @cwq: cwq to insert barrier into 19814690c4abSTejun Heo * @barr: wq_barrier to insert 1982affee4b2STejun Heo * @target: target work to attach @barr to 1983affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 19844690c4abSTejun Heo * 1985affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 1986affee4b2STejun Heo * @target finishes execution. Please note that the ordering 1987affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 1988affee4b2STejun Heo * cpu. 1989affee4b2STejun Heo * 1990affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 1991affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 1992affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 1993affee4b2STejun Heo * flag of the previous work while there must be a valid next work 1994affee4b2STejun Heo * after a work with LINKED flag set. 1995affee4b2STejun Heo * 1996affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 1997affee4b2STejun Heo * underneath us, so we can't reliably determine cwq from @target. 19984690c4abSTejun Heo * 19994690c4abSTejun Heo * CONTEXT: 20008b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 20014690c4abSTejun Heo */ 200283c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 2003affee4b2STejun Heo struct wq_barrier *barr, 2004affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2005fc2e4d70SOleg Nesterov { 2006affee4b2STejun Heo struct list_head *head; 2007affee4b2STejun Heo unsigned int linked = 0; 2008affee4b2STejun Heo 2009dc186ad7SThomas Gleixner /* 20108b03ae3cSTejun Heo * debugobject calls are safe here even with gcwq->lock locked 2011dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2012dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2013dc186ad7SThomas Gleixner * might deadlock. 2014dc186ad7SThomas Gleixner */ 2015dc186ad7SThomas Gleixner INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); 201622df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2017fc2e4d70SOleg Nesterov init_completion(&barr->done); 201883c22520SOleg Nesterov 2019affee4b2STejun Heo /* 2020affee4b2STejun Heo * If @target is currently being executed, schedule the 2021affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2022affee4b2STejun Heo */ 2023affee4b2STejun Heo if (worker) 2024affee4b2STejun Heo head = worker->scheduled.next; 2025affee4b2STejun Heo else { 2026affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2027affee4b2STejun Heo 2028affee4b2STejun Heo head = target->entry.next; 2029affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2030affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2031affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2032affee4b2STejun Heo } 2033affee4b2STejun Heo 2034dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2035affee4b2STejun Heo insert_work(cwq, &barr->work, head, 2036affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2037fc2e4d70SOleg Nesterov } 2038fc2e4d70SOleg Nesterov 203973f53c4aSTejun Heo /** 204073f53c4aSTejun Heo * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing 204173f53c4aSTejun Heo * @wq: workqueue being flushed 204273f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 204373f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 204473f53c4aSTejun Heo * 204573f53c4aSTejun Heo * Prepare cwqs for workqueue flushing. 204673f53c4aSTejun Heo * 204773f53c4aSTejun Heo * If @flush_color is non-negative, flush_color on all cwqs should be 204873f53c4aSTejun Heo * -1. If no cwq has in-flight commands at the specified color, all 204973f53c4aSTejun Heo * cwq->flush_color's stay at -1 and %false is returned. If any cwq 205073f53c4aSTejun Heo * has in flight commands, its cwq->flush_color is set to 205173f53c4aSTejun Heo * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq 205273f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 205373f53c4aSTejun Heo * 205473f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 205573f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 205673f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 205773f53c4aSTejun Heo * is returned. 205873f53c4aSTejun Heo * 205973f53c4aSTejun Heo * If @work_color is non-negative, all cwqs should have the same 206073f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 206173f53c4aSTejun Heo * advanced to @work_color. 206273f53c4aSTejun Heo * 206373f53c4aSTejun Heo * CONTEXT: 206473f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 206573f53c4aSTejun Heo * 206673f53c4aSTejun Heo * RETURNS: 206773f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 206873f53c4aSTejun Heo * otherwise. 206973f53c4aSTejun Heo */ 207073f53c4aSTejun Heo static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, 207173f53c4aSTejun Heo int flush_color, int work_color) 20721da177e4SLinus Torvalds { 207373f53c4aSTejun Heo bool wait = false; 207473f53c4aSTejun Heo unsigned int cpu; 20751da177e4SLinus Torvalds 207673f53c4aSTejun Heo if (flush_color >= 0) { 207773f53c4aSTejun Heo BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); 207873f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 1); 207973f53c4aSTejun Heo } 208073f53c4aSTejun Heo 2081f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 208273f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 20838b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 20842355b70fSLai Jiangshan 20858b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 208673f53c4aSTejun Heo 208773f53c4aSTejun Heo if (flush_color >= 0) { 208873f53c4aSTejun Heo BUG_ON(cwq->flush_color != -1); 208973f53c4aSTejun Heo 209073f53c4aSTejun Heo if (cwq->nr_in_flight[flush_color]) { 209173f53c4aSTejun Heo cwq->flush_color = flush_color; 209273f53c4aSTejun Heo atomic_inc(&wq->nr_cwqs_to_flush); 209373f53c4aSTejun Heo wait = true; 209483c22520SOleg Nesterov } 209573f53c4aSTejun Heo } 209673f53c4aSTejun Heo 209773f53c4aSTejun Heo if (work_color >= 0) { 209873f53c4aSTejun Heo BUG_ON(work_color != work_next_color(cwq->work_color)); 209973f53c4aSTejun Heo cwq->work_color = work_color; 210073f53c4aSTejun Heo } 210173f53c4aSTejun Heo 21028b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 2103dc186ad7SThomas Gleixner } 210414441960SOleg Nesterov 210573f53c4aSTejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) 210673f53c4aSTejun Heo complete(&wq->first_flusher->done); 210773f53c4aSTejun Heo 210873f53c4aSTejun Heo return wait; 210983c22520SOleg Nesterov } 21101da177e4SLinus Torvalds 21110fcb78c2SRolf Eike Beer /** 21121da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 21130fcb78c2SRolf Eike Beer * @wq: workqueue to flush 21141da177e4SLinus Torvalds * 21151da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 21161da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 21171da177e4SLinus Torvalds * 2118fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2119fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 21201da177e4SLinus Torvalds */ 21217ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 21221da177e4SLinus Torvalds { 212373f53c4aSTejun Heo struct wq_flusher this_flusher = { 212473f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 212573f53c4aSTejun Heo .flush_color = -1, 212673f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 212773f53c4aSTejun Heo }; 212873f53c4aSTejun Heo int next_color; 2129b1f4ec17SOleg Nesterov 21303295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 21313295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 213273f53c4aSTejun Heo 213373f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 213473f53c4aSTejun Heo 213573f53c4aSTejun Heo /* 213673f53c4aSTejun Heo * Start-to-wait phase 213773f53c4aSTejun Heo */ 213873f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 213973f53c4aSTejun Heo 214073f53c4aSTejun Heo if (next_color != wq->flush_color) { 214173f53c4aSTejun Heo /* 214273f53c4aSTejun Heo * Color space is not full. The current work_color 214373f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 214473f53c4aSTejun Heo * by one. 214573f53c4aSTejun Heo */ 214673f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow)); 214773f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 214873f53c4aSTejun Heo wq->work_color = next_color; 214973f53c4aSTejun Heo 215073f53c4aSTejun Heo if (!wq->first_flusher) { 215173f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 215273f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 215373f53c4aSTejun Heo 215473f53c4aSTejun Heo wq->first_flusher = &this_flusher; 215573f53c4aSTejun Heo 215673f53c4aSTejun Heo if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, 215773f53c4aSTejun Heo wq->work_color)) { 215873f53c4aSTejun Heo /* nothing to flush, done */ 215973f53c4aSTejun Heo wq->flush_color = next_color; 216073f53c4aSTejun Heo wq->first_flusher = NULL; 216173f53c4aSTejun Heo goto out_unlock; 216273f53c4aSTejun Heo } 216373f53c4aSTejun Heo } else { 216473f53c4aSTejun Heo /* wait in queue */ 216573f53c4aSTejun Heo BUG_ON(wq->flush_color == this_flusher.flush_color); 216673f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 216773f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 216873f53c4aSTejun Heo } 216973f53c4aSTejun Heo } else { 217073f53c4aSTejun Heo /* 217173f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 217273f53c4aSTejun Heo * The next flush completion will assign us 217373f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 217473f53c4aSTejun Heo */ 217573f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 217673f53c4aSTejun Heo } 217773f53c4aSTejun Heo 217873f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 217973f53c4aSTejun Heo 218073f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 218173f53c4aSTejun Heo 218273f53c4aSTejun Heo /* 218373f53c4aSTejun Heo * Wake-up-and-cascade phase 218473f53c4aSTejun Heo * 218573f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 218673f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 218773f53c4aSTejun Heo */ 218873f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 218973f53c4aSTejun Heo return; 219073f53c4aSTejun Heo 219173f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 219273f53c4aSTejun Heo 21934ce48b37STejun Heo /* we might have raced, check again with mutex held */ 21944ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 21954ce48b37STejun Heo goto out_unlock; 21964ce48b37STejun Heo 219773f53c4aSTejun Heo wq->first_flusher = NULL; 219873f53c4aSTejun Heo 219973f53c4aSTejun Heo BUG_ON(!list_empty(&this_flusher.list)); 220073f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 220173f53c4aSTejun Heo 220273f53c4aSTejun Heo while (true) { 220373f53c4aSTejun Heo struct wq_flusher *next, *tmp; 220473f53c4aSTejun Heo 220573f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 220673f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 220773f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 220873f53c4aSTejun Heo break; 220973f53c4aSTejun Heo list_del_init(&next->list); 221073f53c4aSTejun Heo complete(&next->done); 221173f53c4aSTejun Heo } 221273f53c4aSTejun Heo 221373f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow) && 221473f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 221573f53c4aSTejun Heo 221673f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 221773f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 221873f53c4aSTejun Heo 221973f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 222073f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 222173f53c4aSTejun Heo /* 222273f53c4aSTejun Heo * Assign the same color to all overflowed 222373f53c4aSTejun Heo * flushers, advance work_color and append to 222473f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 222573f53c4aSTejun Heo * phase for these overflowed flushers. 222673f53c4aSTejun Heo */ 222773f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 222873f53c4aSTejun Heo tmp->flush_color = wq->work_color; 222973f53c4aSTejun Heo 223073f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 223173f53c4aSTejun Heo 223273f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 223373f53c4aSTejun Heo &wq->flusher_queue); 223473f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 223573f53c4aSTejun Heo } 223673f53c4aSTejun Heo 223773f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 223873f53c4aSTejun Heo BUG_ON(wq->flush_color != wq->work_color); 223973f53c4aSTejun Heo break; 224073f53c4aSTejun Heo } 224173f53c4aSTejun Heo 224273f53c4aSTejun Heo /* 224373f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 224473f53c4aSTejun Heo * the new first flusher and arm cwqs. 224573f53c4aSTejun Heo */ 224673f53c4aSTejun Heo BUG_ON(wq->flush_color == wq->work_color); 224773f53c4aSTejun Heo BUG_ON(wq->flush_color != next->flush_color); 224873f53c4aSTejun Heo 224973f53c4aSTejun Heo list_del_init(&next->list); 225073f53c4aSTejun Heo wq->first_flusher = next; 225173f53c4aSTejun Heo 225273f53c4aSTejun Heo if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) 225373f53c4aSTejun Heo break; 225473f53c4aSTejun Heo 225573f53c4aSTejun Heo /* 225673f53c4aSTejun Heo * Meh... this color is already done, clear first 225773f53c4aSTejun Heo * flusher and repeat cascading. 225873f53c4aSTejun Heo */ 225973f53c4aSTejun Heo wq->first_flusher = NULL; 226073f53c4aSTejun Heo } 226173f53c4aSTejun Heo 226273f53c4aSTejun Heo out_unlock: 226373f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 22641da177e4SLinus Torvalds } 2265ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 22661da177e4SLinus Torvalds 2267db700897SOleg Nesterov /** 2268db700897SOleg Nesterov * flush_work - block until a work_struct's callback has terminated 2269db700897SOleg Nesterov * @work: the work which is to be flushed 2270db700897SOleg Nesterov * 2271a67da70dSOleg Nesterov * Returns false if @work has already terminated. 2272a67da70dSOleg Nesterov * 2273db700897SOleg Nesterov * It is expected that, prior to calling flush_work(), the caller has 2274db700897SOleg Nesterov * arranged for the work to not be requeued, otherwise it doesn't make 2275db700897SOleg Nesterov * sense to use this function. 2276db700897SOleg Nesterov */ 2277db700897SOleg Nesterov int flush_work(struct work_struct *work) 2278db700897SOleg Nesterov { 2279affee4b2STejun Heo struct worker *worker = NULL; 22808b03ae3cSTejun Heo struct global_cwq *gcwq; 22817a22ad75STejun Heo struct cpu_workqueue_struct *cwq; 2282db700897SOleg Nesterov struct wq_barrier barr; 2283db700897SOleg Nesterov 2284db700897SOleg Nesterov might_sleep(); 22857a22ad75STejun Heo gcwq = get_work_gcwq(work); 22867a22ad75STejun Heo if (!gcwq) 2287db700897SOleg Nesterov return 0; 2288a67da70dSOleg Nesterov 22898b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2290db700897SOleg Nesterov if (!list_empty(&work->entry)) { 2291db700897SOleg Nesterov /* 2292db700897SOleg Nesterov * See the comment near try_to_grab_pending()->smp_rmb(). 22937a22ad75STejun Heo * If it was re-queued to a different gcwq under us, we 22947a22ad75STejun Heo * are not going to wait. 2295db700897SOleg Nesterov */ 2296db700897SOleg Nesterov smp_rmb(); 22977a22ad75STejun Heo cwq = get_work_cwq(work); 22987a22ad75STejun Heo if (unlikely(!cwq || gcwq != cwq->gcwq)) 22994690c4abSTejun Heo goto already_gone; 2300db700897SOleg Nesterov } else { 23017a22ad75STejun Heo worker = find_worker_executing_work(gcwq, work); 2302affee4b2STejun Heo if (!worker) 23034690c4abSTejun Heo goto already_gone; 23047a22ad75STejun Heo cwq = worker->current_cwq; 2305db700897SOleg Nesterov } 2306db700897SOleg Nesterov 2307affee4b2STejun Heo insert_wq_barrier(cwq, &barr, work, worker); 23088b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23097a22ad75STejun Heo 23107a22ad75STejun Heo lock_map_acquire(&cwq->wq->lockdep_map); 23117a22ad75STejun Heo lock_map_release(&cwq->wq->lockdep_map); 23127a22ad75STejun Heo 2313db700897SOleg Nesterov wait_for_completion(&barr.done); 2314dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2315db700897SOleg Nesterov return 1; 23164690c4abSTejun Heo already_gone: 23178b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23184690c4abSTejun Heo return 0; 2319db700897SOleg Nesterov } 2320db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2321db700897SOleg Nesterov 23226e84d644SOleg Nesterov /* 23231f1f642eSOleg Nesterov * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, 23246e84d644SOleg Nesterov * so this work can't be re-armed in any way. 23256e84d644SOleg Nesterov */ 23266e84d644SOleg Nesterov static int try_to_grab_pending(struct work_struct *work) 23276e84d644SOleg Nesterov { 23288b03ae3cSTejun Heo struct global_cwq *gcwq; 23291f1f642eSOleg Nesterov int ret = -1; 23306e84d644SOleg Nesterov 233122df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 23321f1f642eSOleg Nesterov return 0; 23336e84d644SOleg Nesterov 23346e84d644SOleg Nesterov /* 23356e84d644SOleg Nesterov * The queueing is in progress, or it is already queued. Try to 23366e84d644SOleg Nesterov * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 23376e84d644SOleg Nesterov */ 23387a22ad75STejun Heo gcwq = get_work_gcwq(work); 23397a22ad75STejun Heo if (!gcwq) 23406e84d644SOleg Nesterov return ret; 23416e84d644SOleg Nesterov 23428b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 23436e84d644SOleg Nesterov if (!list_empty(&work->entry)) { 23446e84d644SOleg Nesterov /* 23457a22ad75STejun Heo * This work is queued, but perhaps we locked the wrong gcwq. 23466e84d644SOleg Nesterov * In that case we must see the new value after rmb(), see 23476e84d644SOleg Nesterov * insert_work()->wmb(). 23486e84d644SOleg Nesterov */ 23496e84d644SOleg Nesterov smp_rmb(); 23507a22ad75STejun Heo if (gcwq == get_work_gcwq(work)) { 2351dc186ad7SThomas Gleixner debug_work_deactivate(work); 23526e84d644SOleg Nesterov list_del_init(&work->entry); 23537a22ad75STejun Heo cwq_dec_nr_in_flight(get_work_cwq(work), 23547a22ad75STejun Heo get_work_color(work)); 23556e84d644SOleg Nesterov ret = 1; 23566e84d644SOleg Nesterov } 23576e84d644SOleg Nesterov } 23588b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23596e84d644SOleg Nesterov 23606e84d644SOleg Nesterov return ret; 23616e84d644SOleg Nesterov } 23626e84d644SOleg Nesterov 23637a22ad75STejun Heo static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) 2364b89deed3SOleg Nesterov { 2365b89deed3SOleg Nesterov struct wq_barrier barr; 2366affee4b2STejun Heo struct worker *worker; 2367b89deed3SOleg Nesterov 23688b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2369affee4b2STejun Heo 23707a22ad75STejun Heo worker = find_worker_executing_work(gcwq, work); 23717a22ad75STejun Heo if (unlikely(worker)) 23727a22ad75STejun Heo insert_wq_barrier(worker->current_cwq, &barr, work, worker); 2373affee4b2STejun Heo 23748b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 2375b89deed3SOleg Nesterov 2376affee4b2STejun Heo if (unlikely(worker)) { 2377b89deed3SOleg Nesterov wait_for_completion(&barr.done); 2378dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2379dc186ad7SThomas Gleixner } 2380b89deed3SOleg Nesterov } 2381b89deed3SOleg Nesterov 23826e84d644SOleg Nesterov static void wait_on_work(struct work_struct *work) 2383b89deed3SOleg Nesterov { 2384b1f4ec17SOleg Nesterov int cpu; 2385b89deed3SOleg Nesterov 2386f293ea92SOleg Nesterov might_sleep(); 2387f293ea92SOleg Nesterov 23883295f0efSIngo Molnar lock_map_acquire(&work->lockdep_map); 23893295f0efSIngo Molnar lock_map_release(&work->lockdep_map); 23904e6045f1SJohannes Berg 2391f3421797STejun Heo for_each_gcwq_cpu(cpu) 23927a22ad75STejun Heo wait_on_cpu_work(get_gcwq(cpu), work); 23936e84d644SOleg Nesterov } 23946e84d644SOleg Nesterov 23951f1f642eSOleg Nesterov static int __cancel_work_timer(struct work_struct *work, 23961f1f642eSOleg Nesterov struct timer_list* timer) 23971f1f642eSOleg Nesterov { 23981f1f642eSOleg Nesterov int ret; 23991f1f642eSOleg Nesterov 24001f1f642eSOleg Nesterov do { 24011f1f642eSOleg Nesterov ret = (timer && likely(del_timer(timer))); 24021f1f642eSOleg Nesterov if (!ret) 24031f1f642eSOleg Nesterov ret = try_to_grab_pending(work); 24041f1f642eSOleg Nesterov wait_on_work(work); 24051f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 24061f1f642eSOleg Nesterov 24077a22ad75STejun Heo clear_work_data(work); 24081f1f642eSOleg Nesterov return ret; 24091f1f642eSOleg Nesterov } 24101f1f642eSOleg Nesterov 24116e84d644SOleg Nesterov /** 24126e84d644SOleg Nesterov * cancel_work_sync - block until a work_struct's callback has terminated 24136e84d644SOleg Nesterov * @work: the work which is to be flushed 24146e84d644SOleg Nesterov * 24151f1f642eSOleg Nesterov * Returns true if @work was pending. 24161f1f642eSOleg Nesterov * 24176e84d644SOleg Nesterov * cancel_work_sync() will cancel the work if it is queued. If the work's 24186e84d644SOleg Nesterov * callback appears to be running, cancel_work_sync() will block until it 24196e84d644SOleg Nesterov * has completed. 24206e84d644SOleg Nesterov * 24216e84d644SOleg Nesterov * It is possible to use this function if the work re-queues itself. It can 24226e84d644SOleg Nesterov * cancel the work even if it migrates to another workqueue, however in that 24236e84d644SOleg Nesterov * case it only guarantees that work->func() has completed on the last queued 24246e84d644SOleg Nesterov * workqueue. 24256e84d644SOleg Nesterov * 24266e84d644SOleg Nesterov * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not 24276e84d644SOleg Nesterov * pending, otherwise it goes into a busy-wait loop until the timer expires. 24286e84d644SOleg Nesterov * 24296e84d644SOleg Nesterov * The caller must ensure that workqueue_struct on which this work was last 24306e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 24316e84d644SOleg Nesterov */ 24321f1f642eSOleg Nesterov int cancel_work_sync(struct work_struct *work) 24336e84d644SOleg Nesterov { 24341f1f642eSOleg Nesterov return __cancel_work_timer(work, NULL); 2435b89deed3SOleg Nesterov } 243628e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2437b89deed3SOleg Nesterov 24386e84d644SOleg Nesterov /** 2439f5a421a4SOleg Nesterov * cancel_delayed_work_sync - reliably kill off a delayed work. 24406e84d644SOleg Nesterov * @dwork: the delayed work struct 24416e84d644SOleg Nesterov * 24421f1f642eSOleg Nesterov * Returns true if @dwork was pending. 24431f1f642eSOleg Nesterov * 24446e84d644SOleg Nesterov * It is possible to use this function if @dwork rearms itself via queue_work() 24456e84d644SOleg Nesterov * or queue_delayed_work(). See also the comment for cancel_work_sync(). 24466e84d644SOleg Nesterov */ 24471f1f642eSOleg Nesterov int cancel_delayed_work_sync(struct delayed_work *dwork) 24486e84d644SOleg Nesterov { 24491f1f642eSOleg Nesterov return __cancel_work_timer(&dwork->work, &dwork->timer); 24506e84d644SOleg Nesterov } 2451f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 24521da177e4SLinus Torvalds 24530fcb78c2SRolf Eike Beer /** 24540fcb78c2SRolf Eike Beer * schedule_work - put work task in global workqueue 24550fcb78c2SRolf Eike Beer * @work: job to be done 24560fcb78c2SRolf Eike Beer * 24575b0f437dSBart Van Assche * Returns zero if @work was already on the kernel-global workqueue and 24585b0f437dSBart Van Assche * non-zero otherwise. 24595b0f437dSBart Van Assche * 24605b0f437dSBart Van Assche * This puts a job in the kernel-global workqueue if it was not already 24615b0f437dSBart Van Assche * queued and leaves it in the same position on the kernel-global 24625b0f437dSBart Van Assche * workqueue otherwise. 24630fcb78c2SRolf Eike Beer */ 24647ad5b3a5SHarvey Harrison int schedule_work(struct work_struct *work) 24651da177e4SLinus Torvalds { 2466d320c038STejun Heo return queue_work(system_wq, work); 24671da177e4SLinus Torvalds } 2468ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_work); 24691da177e4SLinus Torvalds 2470c1a220e7SZhang Rui /* 2471c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2472c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2473c1a220e7SZhang Rui * @work: job to be done 2474c1a220e7SZhang Rui * 2475c1a220e7SZhang Rui * This puts a job on a specific cpu 2476c1a220e7SZhang Rui */ 2477c1a220e7SZhang Rui int schedule_work_on(int cpu, struct work_struct *work) 2478c1a220e7SZhang Rui { 2479d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 2480c1a220e7SZhang Rui } 2481c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 2482c1a220e7SZhang Rui 24830fcb78c2SRolf Eike Beer /** 24840fcb78c2SRolf Eike Beer * schedule_delayed_work - put work task in global workqueue after delay 248552bad64dSDavid Howells * @dwork: job to be done 248652bad64dSDavid Howells * @delay: number of jiffies to wait or 0 for immediate execution 24870fcb78c2SRolf Eike Beer * 24880fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 24890fcb78c2SRolf Eike Beer * workqueue. 24900fcb78c2SRolf Eike Beer */ 24917ad5b3a5SHarvey Harrison int schedule_delayed_work(struct delayed_work *dwork, 249282f67cd9SIngo Molnar unsigned long delay) 24931da177e4SLinus Torvalds { 2494d320c038STejun Heo return queue_delayed_work(system_wq, dwork, delay); 24951da177e4SLinus Torvalds } 2496ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work); 24971da177e4SLinus Torvalds 24980fcb78c2SRolf Eike Beer /** 24998c53e463SLinus Torvalds * flush_delayed_work - block until a dwork_struct's callback has terminated 25008c53e463SLinus Torvalds * @dwork: the delayed work which is to be flushed 25018c53e463SLinus Torvalds * 25028c53e463SLinus Torvalds * Any timeout is cancelled, and any pending work is run immediately. 25038c53e463SLinus Torvalds */ 25048c53e463SLinus Torvalds void flush_delayed_work(struct delayed_work *dwork) 25058c53e463SLinus Torvalds { 25068c53e463SLinus Torvalds if (del_timer_sync(&dwork->timer)) { 25077a22ad75STejun Heo __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq, 25084690c4abSTejun Heo &dwork->work); 25098c53e463SLinus Torvalds put_cpu(); 25108c53e463SLinus Torvalds } 25118c53e463SLinus Torvalds flush_work(&dwork->work); 25128c53e463SLinus Torvalds } 25138c53e463SLinus Torvalds EXPORT_SYMBOL(flush_delayed_work); 25148c53e463SLinus Torvalds 25158c53e463SLinus Torvalds /** 25160fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 25170fcb78c2SRolf Eike Beer * @cpu: cpu to use 251852bad64dSDavid Howells * @dwork: job to be done 25190fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 25200fcb78c2SRolf Eike Beer * 25210fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 25220fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 25230fcb78c2SRolf Eike Beer */ 25241da177e4SLinus Torvalds int schedule_delayed_work_on(int cpu, 252552bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 25261da177e4SLinus Torvalds { 2527d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 25281da177e4SLinus Torvalds } 2529ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 25301da177e4SLinus Torvalds 2531b6136773SAndrew Morton /** 2532b6136773SAndrew Morton * schedule_on_each_cpu - call a function on each online CPU from keventd 2533b6136773SAndrew Morton * @func: the function to call 2534b6136773SAndrew Morton * 2535b6136773SAndrew Morton * Returns zero on success. 2536b6136773SAndrew Morton * Returns -ve errno on failure. 2537b6136773SAndrew Morton * 2538b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 2539b6136773SAndrew Morton */ 254065f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 254115316ba8SChristoph Lameter { 254215316ba8SChristoph Lameter int cpu; 2543b6136773SAndrew Morton struct work_struct *works; 254415316ba8SChristoph Lameter 2545b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 2546b6136773SAndrew Morton if (!works) 254715316ba8SChristoph Lameter return -ENOMEM; 2548b6136773SAndrew Morton 254995402b38SGautham R Shenoy get_online_cpus(); 255093981800STejun Heo 255115316ba8SChristoph Lameter for_each_online_cpu(cpu) { 25529bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 25539bfb1839SIngo Molnar 25549bfb1839SIngo Molnar INIT_WORK(work, func); 25558de6d308SOleg Nesterov schedule_work_on(cpu, work); 255615316ba8SChristoph Lameter } 255793981800STejun Heo 255893981800STejun Heo for_each_online_cpu(cpu) 25598616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 256093981800STejun Heo 256195402b38SGautham R Shenoy put_online_cpus(); 2562b6136773SAndrew Morton free_percpu(works); 256315316ba8SChristoph Lameter return 0; 256415316ba8SChristoph Lameter } 256515316ba8SChristoph Lameter 2566eef6a7d5SAlan Stern /** 2567eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 2568eef6a7d5SAlan Stern * 2569eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 2570eef6a7d5SAlan Stern * completion. 2571eef6a7d5SAlan Stern * 2572eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 2573eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 2574eef6a7d5SAlan Stern * will lead to deadlock: 2575eef6a7d5SAlan Stern * 2576eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 2577eef6a7d5SAlan Stern * a lock held by your code or its caller. 2578eef6a7d5SAlan Stern * 2579eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 2580eef6a7d5SAlan Stern * 2581eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 2582eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 2583eef6a7d5SAlan Stern * what locks they need, which you have no control over. 2584eef6a7d5SAlan Stern * 2585eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 2586eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 2587eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 2588eef6a7d5SAlan Stern * cancel_work_sync() instead. 2589eef6a7d5SAlan Stern */ 25901da177e4SLinus Torvalds void flush_scheduled_work(void) 25911da177e4SLinus Torvalds { 2592d320c038STejun Heo flush_workqueue(system_wq); 25931da177e4SLinus Torvalds } 2594ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 25951da177e4SLinus Torvalds 25961da177e4SLinus Torvalds /** 25971fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 25981fa44ecaSJames Bottomley * @fn: the function to execute 25991fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 26001fa44ecaSJames Bottomley * be available when the work executes) 26011fa44ecaSJames Bottomley * 26021fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 26031fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 26041fa44ecaSJames Bottomley * 26051fa44ecaSJames Bottomley * Returns: 0 - function was executed 26061fa44ecaSJames Bottomley * 1 - function was scheduled for execution 26071fa44ecaSJames Bottomley */ 260865f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 26091fa44ecaSJames Bottomley { 26101fa44ecaSJames Bottomley if (!in_interrupt()) { 261165f27f38SDavid Howells fn(&ew->work); 26121fa44ecaSJames Bottomley return 0; 26131fa44ecaSJames Bottomley } 26141fa44ecaSJames Bottomley 261565f27f38SDavid Howells INIT_WORK(&ew->work, fn); 26161fa44ecaSJames Bottomley schedule_work(&ew->work); 26171fa44ecaSJames Bottomley 26181fa44ecaSJames Bottomley return 1; 26191fa44ecaSJames Bottomley } 26201fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 26211fa44ecaSJames Bottomley 26221da177e4SLinus Torvalds int keventd_up(void) 26231da177e4SLinus Torvalds { 2624d320c038STejun Heo return system_wq != NULL; 26251da177e4SLinus Torvalds } 26261da177e4SLinus Torvalds 2627bdbc5dd7STejun Heo static int alloc_cwqs(struct workqueue_struct *wq) 26280f900049STejun Heo { 26290f900049STejun Heo /* 26300f900049STejun Heo * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. 26310f900049STejun Heo * Make sure that the alignment isn't lower than that of 26320f900049STejun Heo * unsigned long long. 26330f900049STejun Heo */ 26340f900049STejun Heo const size_t size = sizeof(struct cpu_workqueue_struct); 26350f900049STejun Heo const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, 26360f900049STejun Heo __alignof__(unsigned long long)); 2637931ac77eSTejun Heo #ifdef CONFIG_SMP 2638931ac77eSTejun Heo bool percpu = !(wq->flags & WQ_UNBOUND); 2639931ac77eSTejun Heo #else 2640931ac77eSTejun Heo bool percpu = false; 2641931ac77eSTejun Heo #endif 2642f3421797STejun Heo 2643931ac77eSTejun Heo if (percpu) 2644f3421797STejun Heo wq->cpu_wq.pcpu = __alloc_percpu(size, align); 2645931ac77eSTejun Heo else { 26460f900049STejun Heo void *ptr; 26470f900049STejun Heo 26480f900049STejun Heo /* 2649f3421797STejun Heo * Allocate enough room to align cwq and put an extra 2650f3421797STejun Heo * pointer at the end pointing back to the originally 2651f3421797STejun Heo * allocated pointer which will be used for free. 26520f900049STejun Heo */ 2653bdbc5dd7STejun Heo ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); 2654bdbc5dd7STejun Heo if (ptr) { 2655bdbc5dd7STejun Heo wq->cpu_wq.single = PTR_ALIGN(ptr, align); 2656bdbc5dd7STejun Heo *(void **)(wq->cpu_wq.single + 1) = ptr; 2657bdbc5dd7STejun Heo } 2658f3421797STejun Heo } 2659f3421797STejun Heo 26600f900049STejun Heo /* just in case, make sure it's actually aligned */ 2661bdbc5dd7STejun Heo BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); 2662bdbc5dd7STejun Heo return wq->cpu_wq.v ? 0 : -ENOMEM; 26630f900049STejun Heo } 26640f900049STejun Heo 2665bdbc5dd7STejun Heo static void free_cwqs(struct workqueue_struct *wq) 26660f900049STejun Heo { 2667931ac77eSTejun Heo #ifdef CONFIG_SMP 2668931ac77eSTejun Heo bool percpu = !(wq->flags & WQ_UNBOUND); 2669931ac77eSTejun Heo #else 2670931ac77eSTejun Heo bool percpu = false; 2671931ac77eSTejun Heo #endif 2672931ac77eSTejun Heo 2673931ac77eSTejun Heo if (percpu) 2674bdbc5dd7STejun Heo free_percpu(wq->cpu_wq.pcpu); 2675f3421797STejun Heo else if (wq->cpu_wq.single) { 2676f3421797STejun Heo /* the pointer to free is stored right after the cwq */ 2677f3421797STejun Heo kfree(*(void **)(wq->cpu_wq.single + 1)); 2678f3421797STejun Heo } 26790f900049STejun Heo } 26800f900049STejun Heo 2681f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 2682f3421797STejun Heo const char *name) 2683b71ab8c2STejun Heo { 2684f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 2685f3421797STejun Heo 2686f3421797STejun Heo if (max_active < 1 || max_active > lim) 2687b71ab8c2STejun Heo printk(KERN_WARNING "workqueue: max_active %d requested for %s " 2688b71ab8c2STejun Heo "is out of range, clamping between %d and %d\n", 2689f3421797STejun Heo max_active, name, 1, lim); 2690b71ab8c2STejun Heo 2691f3421797STejun Heo return clamp_val(max_active, 1, lim); 2692b71ab8c2STejun Heo } 2693b71ab8c2STejun Heo 2694d320c038STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *name, 269597e37d7bSTejun Heo unsigned int flags, 26961e19ffc6STejun Heo int max_active, 2697eb13ba87SJohannes Berg struct lock_class_key *key, 2698eb13ba87SJohannes Berg const char *lock_name) 26993af24433SOleg Nesterov { 27003af24433SOleg Nesterov struct workqueue_struct *wq; 2701c34056a3STejun Heo unsigned int cpu; 27023af24433SOleg Nesterov 2703f3421797STejun Heo /* 2704f3421797STejun Heo * Unbound workqueues aren't concurrency managed and should be 2705f3421797STejun Heo * dispatched to workers immediately. 2706f3421797STejun Heo */ 2707f3421797STejun Heo if (flags & WQ_UNBOUND) 2708f3421797STejun Heo flags |= WQ_HIGHPRI; 2709f3421797STejun Heo 2710d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 2711f3421797STejun Heo max_active = wq_clamp_max_active(max_active, flags, name); 27121e19ffc6STejun Heo 27133af24433SOleg Nesterov wq = kzalloc(sizeof(*wq), GFP_KERNEL); 27143af24433SOleg Nesterov if (!wq) 27154690c4abSTejun Heo goto err; 27163af24433SOleg Nesterov 271797e37d7bSTejun Heo wq->flags = flags; 2718a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 271973f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 272073f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 0); 272173f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 272273f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 2723502ca9d8STejun Heo 27243af24433SOleg Nesterov wq->name = name; 2725eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 2726cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 27273af24433SOleg Nesterov 2728bdbc5dd7STejun Heo if (alloc_cwqs(wq) < 0) 2729bdbc5dd7STejun Heo goto err; 2730bdbc5dd7STejun Heo 2731f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 27321537663fSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 27338b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 27341537663fSTejun Heo 27350f900049STejun Heo BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 27368b03ae3cSTejun Heo cwq->gcwq = gcwq; 2737c34056a3STejun Heo cwq->wq = wq; 273873f53c4aSTejun Heo cwq->flush_color = -1; 27391e19ffc6STejun Heo cwq->max_active = max_active; 27401e19ffc6STejun Heo INIT_LIST_HEAD(&cwq->delayed_works); 2741e22bee78STejun Heo } 27421537663fSTejun Heo 2743e22bee78STejun Heo if (flags & WQ_RESCUER) { 2744e22bee78STejun Heo struct worker *rescuer; 2745e22bee78STejun Heo 2746f2e005aaSTejun Heo if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) 2747e22bee78STejun Heo goto err; 2748e22bee78STejun Heo 2749e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 2750e22bee78STejun Heo if (!rescuer) 2751e22bee78STejun Heo goto err; 2752e22bee78STejun Heo 2753e22bee78STejun Heo rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); 2754e22bee78STejun Heo if (IS_ERR(rescuer->task)) 2755e22bee78STejun Heo goto err; 2756e22bee78STejun Heo 2757e22bee78STejun Heo wq->rescuer = rescuer; 2758e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 2759e22bee78STejun Heo wake_up_process(rescuer->task); 27603af24433SOleg Nesterov } 27611537663fSTejun Heo 2762a0a1a5fdSTejun Heo /* 2763a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 2764a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 2765a0a1a5fdSTejun Heo * workqueue to workqueues list. 2766a0a1a5fdSTejun Heo */ 27671537663fSTejun Heo spin_lock(&workqueue_lock); 2768a0a1a5fdSTejun Heo 2769a0a1a5fdSTejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) 2770f3421797STejun Heo for_each_cwq_cpu(cpu, wq) 2771a0a1a5fdSTejun Heo get_cwq(cpu, wq)->max_active = 0; 2772a0a1a5fdSTejun Heo 27731537663fSTejun Heo list_add(&wq->list, &workqueues); 2774a0a1a5fdSTejun Heo 27751537663fSTejun Heo spin_unlock(&workqueue_lock); 27761537663fSTejun Heo 27773af24433SOleg Nesterov return wq; 27784690c4abSTejun Heo err: 27794690c4abSTejun Heo if (wq) { 2780bdbc5dd7STejun Heo free_cwqs(wq); 2781f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 2782e22bee78STejun Heo kfree(wq->rescuer); 27834690c4abSTejun Heo kfree(wq); 27844690c4abSTejun Heo } 27854690c4abSTejun Heo return NULL; 27863af24433SOleg Nesterov } 2787d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 27883af24433SOleg Nesterov 27893af24433SOleg Nesterov /** 27903af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 27913af24433SOleg Nesterov * @wq: target workqueue 27923af24433SOleg Nesterov * 27933af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 27943af24433SOleg Nesterov */ 27953af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 27963af24433SOleg Nesterov { 2797c8e55f36STejun Heo unsigned int cpu; 27983af24433SOleg Nesterov 2799a0a1a5fdSTejun Heo flush_workqueue(wq); 2800a0a1a5fdSTejun Heo 2801a0a1a5fdSTejun Heo /* 2802a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 2803a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 2804a0a1a5fdSTejun Heo */ 280595402b38SGautham R Shenoy spin_lock(&workqueue_lock); 28063af24433SOleg Nesterov list_del(&wq->list); 280795402b38SGautham R Shenoy spin_unlock(&workqueue_lock); 28083af24433SOleg Nesterov 2809e22bee78STejun Heo /* sanity check */ 2810f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 281173f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 281273f53c4aSTejun Heo int i; 281373f53c4aSTejun Heo 281473f53c4aSTejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 281573f53c4aSTejun Heo BUG_ON(cwq->nr_in_flight[i]); 28161e19ffc6STejun Heo BUG_ON(cwq->nr_active); 28171e19ffc6STejun Heo BUG_ON(!list_empty(&cwq->delayed_works)); 281873f53c4aSTejun Heo } 28191537663fSTejun Heo 2820e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 2821e22bee78STejun Heo kthread_stop(wq->rescuer->task); 2822f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 2823e22bee78STejun Heo } 2824e22bee78STejun Heo 2825bdbc5dd7STejun Heo free_cwqs(wq); 28263af24433SOleg Nesterov kfree(wq); 28273af24433SOleg Nesterov } 28283af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 28293af24433SOleg Nesterov 2830dcd989cbSTejun Heo /** 2831dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 2832dcd989cbSTejun Heo * @wq: target workqueue 2833dcd989cbSTejun Heo * @max_active: new max_active value. 2834dcd989cbSTejun Heo * 2835dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 2836dcd989cbSTejun Heo * 2837dcd989cbSTejun Heo * CONTEXT: 2838dcd989cbSTejun Heo * Don't call from IRQ context. 2839dcd989cbSTejun Heo */ 2840dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 2841dcd989cbSTejun Heo { 2842dcd989cbSTejun Heo unsigned int cpu; 2843dcd989cbSTejun Heo 2844f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 2845dcd989cbSTejun Heo 2846dcd989cbSTejun Heo spin_lock(&workqueue_lock); 2847dcd989cbSTejun Heo 2848dcd989cbSTejun Heo wq->saved_max_active = max_active; 2849dcd989cbSTejun Heo 2850f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 2851dcd989cbSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 2852dcd989cbSTejun Heo 2853dcd989cbSTejun Heo spin_lock_irq(&gcwq->lock); 2854dcd989cbSTejun Heo 2855dcd989cbSTejun Heo if (!(wq->flags & WQ_FREEZEABLE) || 2856dcd989cbSTejun Heo !(gcwq->flags & GCWQ_FREEZING)) 2857dcd989cbSTejun Heo get_cwq(gcwq->cpu, wq)->max_active = max_active; 2858dcd989cbSTejun Heo 2859dcd989cbSTejun Heo spin_unlock_irq(&gcwq->lock); 2860dcd989cbSTejun Heo } 2861dcd989cbSTejun Heo 2862dcd989cbSTejun Heo spin_unlock(&workqueue_lock); 2863dcd989cbSTejun Heo } 2864dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 2865dcd989cbSTejun Heo 2866dcd989cbSTejun Heo /** 2867dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 2868dcd989cbSTejun Heo * @cpu: CPU in question 2869dcd989cbSTejun Heo * @wq: target workqueue 2870dcd989cbSTejun Heo * 2871dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 2872dcd989cbSTejun Heo * no synchronization around this function and the test result is 2873dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 2874dcd989cbSTejun Heo * 2875dcd989cbSTejun Heo * RETURNS: 2876dcd989cbSTejun Heo * %true if congested, %false otherwise. 2877dcd989cbSTejun Heo */ 2878dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 2879dcd989cbSTejun Heo { 2880dcd989cbSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2881dcd989cbSTejun Heo 2882dcd989cbSTejun Heo return !list_empty(&cwq->delayed_works); 2883dcd989cbSTejun Heo } 2884dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 2885dcd989cbSTejun Heo 2886dcd989cbSTejun Heo /** 2887dcd989cbSTejun Heo * work_cpu - return the last known associated cpu for @work 2888dcd989cbSTejun Heo * @work: the work of interest 2889dcd989cbSTejun Heo * 2890dcd989cbSTejun Heo * RETURNS: 2891bdbc5dd7STejun Heo * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. 2892dcd989cbSTejun Heo */ 2893dcd989cbSTejun Heo unsigned int work_cpu(struct work_struct *work) 2894dcd989cbSTejun Heo { 2895dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 2896dcd989cbSTejun Heo 2897bdbc5dd7STejun Heo return gcwq ? gcwq->cpu : WORK_CPU_NONE; 2898dcd989cbSTejun Heo } 2899dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_cpu); 2900dcd989cbSTejun Heo 2901dcd989cbSTejun Heo /** 2902dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 2903dcd989cbSTejun Heo * @work: the work to be tested 2904dcd989cbSTejun Heo * 2905dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 2906dcd989cbSTejun Heo * synchronization around this function and the test result is 2907dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 2908dcd989cbSTejun Heo * Especially for reentrant wqs, the pending state might hide the 2909dcd989cbSTejun Heo * running state. 2910dcd989cbSTejun Heo * 2911dcd989cbSTejun Heo * RETURNS: 2912dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 2913dcd989cbSTejun Heo */ 2914dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 2915dcd989cbSTejun Heo { 2916dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 2917dcd989cbSTejun Heo unsigned long flags; 2918dcd989cbSTejun Heo unsigned int ret = 0; 2919dcd989cbSTejun Heo 2920dcd989cbSTejun Heo if (!gcwq) 2921dcd989cbSTejun Heo return false; 2922dcd989cbSTejun Heo 2923dcd989cbSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 2924dcd989cbSTejun Heo 2925dcd989cbSTejun Heo if (work_pending(work)) 2926dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 2927dcd989cbSTejun Heo if (find_worker_executing_work(gcwq, work)) 2928dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 2929dcd989cbSTejun Heo 2930dcd989cbSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 2931dcd989cbSTejun Heo 2932dcd989cbSTejun Heo return ret; 2933dcd989cbSTejun Heo } 2934dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 2935dcd989cbSTejun Heo 2936db7bccf4STejun Heo /* 2937db7bccf4STejun Heo * CPU hotplug. 2938db7bccf4STejun Heo * 2939e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 2940e22bee78STejun Heo * are a lot of assumptions on strong associations among work, cwq and 2941e22bee78STejun Heo * gcwq which make migrating pending and scheduled works very 2942e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 2943e22bee78STejun Heo * gcwqs serve mix of short, long and very long running works making 2944e22bee78STejun Heo * blocked draining impractical. 2945e22bee78STejun Heo * 2946e22bee78STejun Heo * This is solved by allowing a gcwq to be detached from CPU, running 2947e22bee78STejun Heo * it with unbound (rogue) workers and allowing it to be reattached 2948e22bee78STejun Heo * later if the cpu comes back online. A separate thread is created 2949e22bee78STejun Heo * to govern a gcwq in such state and is called the trustee of the 2950e22bee78STejun Heo * gcwq. 2951db7bccf4STejun Heo * 2952db7bccf4STejun Heo * Trustee states and their descriptions. 2953db7bccf4STejun Heo * 2954db7bccf4STejun Heo * START Command state used on startup. On CPU_DOWN_PREPARE, a 2955db7bccf4STejun Heo * new trustee is started with this state. 2956db7bccf4STejun Heo * 2957db7bccf4STejun Heo * IN_CHARGE Once started, trustee will enter this state after 2958e22bee78STejun Heo * assuming the manager role and making all existing 2959e22bee78STejun Heo * workers rogue. DOWN_PREPARE waits for trustee to 2960e22bee78STejun Heo * enter this state. After reaching IN_CHARGE, trustee 2961e22bee78STejun Heo * tries to execute the pending worklist until it's empty 2962e22bee78STejun Heo * and the state is set to BUTCHER, or the state is set 2963e22bee78STejun Heo * to RELEASE. 2964db7bccf4STejun Heo * 2965db7bccf4STejun Heo * BUTCHER Command state which is set by the cpu callback after 2966db7bccf4STejun Heo * the cpu has went down. Once this state is set trustee 2967db7bccf4STejun Heo * knows that there will be no new works on the worklist 2968db7bccf4STejun Heo * and once the worklist is empty it can proceed to 2969db7bccf4STejun Heo * killing idle workers. 2970db7bccf4STejun Heo * 2971db7bccf4STejun Heo * RELEASE Command state which is set by the cpu callback if the 2972db7bccf4STejun Heo * cpu down has been canceled or it has come online 2973db7bccf4STejun Heo * again. After recognizing this state, trustee stops 2974e22bee78STejun Heo * trying to drain or butcher and clears ROGUE, rebinds 2975e22bee78STejun Heo * all remaining workers back to the cpu and releases 2976e22bee78STejun Heo * manager role. 2977db7bccf4STejun Heo * 2978db7bccf4STejun Heo * DONE Trustee will enter this state after BUTCHER or RELEASE 2979db7bccf4STejun Heo * is complete. 2980db7bccf4STejun Heo * 2981db7bccf4STejun Heo * trustee CPU draining 2982db7bccf4STejun Heo * took over down complete 2983db7bccf4STejun Heo * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE 2984db7bccf4STejun Heo * | | ^ 2985db7bccf4STejun Heo * | CPU is back online v return workers | 2986db7bccf4STejun Heo * ----------------> RELEASE -------------- 2987db7bccf4STejun Heo */ 2988db7bccf4STejun Heo 2989db7bccf4STejun Heo /** 2990db7bccf4STejun Heo * trustee_wait_event_timeout - timed event wait for trustee 2991db7bccf4STejun Heo * @cond: condition to wait for 2992db7bccf4STejun Heo * @timeout: timeout in jiffies 2993db7bccf4STejun Heo * 2994db7bccf4STejun Heo * wait_event_timeout() for trustee to use. Handles locking and 2995db7bccf4STejun Heo * checks for RELEASE request. 2996db7bccf4STejun Heo * 2997db7bccf4STejun Heo * CONTEXT: 2998db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2999db7bccf4STejun Heo * multiple times. To be used by trustee. 3000db7bccf4STejun Heo * 3001db7bccf4STejun Heo * RETURNS: 3002db7bccf4STejun Heo * Positive indicating left time if @cond is satisfied, 0 if timed 3003db7bccf4STejun Heo * out, -1 if canceled. 3004db7bccf4STejun Heo */ 3005db7bccf4STejun Heo #define trustee_wait_event_timeout(cond, timeout) ({ \ 3006db7bccf4STejun Heo long __ret = (timeout); \ 3007db7bccf4STejun Heo while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ 3008db7bccf4STejun Heo __ret) { \ 3009db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); \ 3010db7bccf4STejun Heo __wait_event_timeout(gcwq->trustee_wait, (cond) || \ 3011db7bccf4STejun Heo (gcwq->trustee_state == TRUSTEE_RELEASE), \ 3012db7bccf4STejun Heo __ret); \ 3013db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); \ 3014db7bccf4STejun Heo } \ 3015db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ 3016db7bccf4STejun Heo }) 3017db7bccf4STejun Heo 3018db7bccf4STejun Heo /** 3019db7bccf4STejun Heo * trustee_wait_event - event wait for trustee 3020db7bccf4STejun Heo * @cond: condition to wait for 3021db7bccf4STejun Heo * 3022db7bccf4STejun Heo * wait_event() for trustee to use. Automatically handles locking and 3023db7bccf4STejun Heo * checks for CANCEL request. 3024db7bccf4STejun Heo * 3025db7bccf4STejun Heo * CONTEXT: 3026db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3027db7bccf4STejun Heo * multiple times. To be used by trustee. 3028db7bccf4STejun Heo * 3029db7bccf4STejun Heo * RETURNS: 3030db7bccf4STejun Heo * 0 if @cond is satisfied, -1 if canceled. 3031db7bccf4STejun Heo */ 3032db7bccf4STejun Heo #define trustee_wait_event(cond) ({ \ 3033db7bccf4STejun Heo long __ret1; \ 3034db7bccf4STejun Heo __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ 3035db7bccf4STejun Heo __ret1 < 0 ? -1 : 0; \ 3036db7bccf4STejun Heo }) 3037db7bccf4STejun Heo 3038db7bccf4STejun Heo static int __cpuinit trustee_thread(void *__gcwq) 3039db7bccf4STejun Heo { 3040db7bccf4STejun Heo struct global_cwq *gcwq = __gcwq; 3041db7bccf4STejun Heo struct worker *worker; 3042e22bee78STejun Heo struct work_struct *work; 3043db7bccf4STejun Heo struct hlist_node *pos; 3044e22bee78STejun Heo long rc; 3045db7bccf4STejun Heo int i; 3046db7bccf4STejun Heo 3047db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3048db7bccf4STejun Heo 3049db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3050db7bccf4STejun Heo /* 3051e22bee78STejun Heo * Claim the manager position and make all workers rogue. 3052e22bee78STejun Heo * Trustee must be bound to the target cpu and can't be 3053e22bee78STejun Heo * cancelled. 3054db7bccf4STejun Heo */ 3055db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3056e22bee78STejun Heo rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); 3057e22bee78STejun Heo BUG_ON(rc < 0); 3058e22bee78STejun Heo 3059e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 3060db7bccf4STejun Heo 3061db7bccf4STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) 3062cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3063db7bccf4STejun Heo 3064db7bccf4STejun Heo for_each_busy_worker(worker, i, pos, gcwq) 3065cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3066db7bccf4STejun Heo 3067db7bccf4STejun Heo /* 3068e22bee78STejun Heo * Call schedule() so that we cross rq->lock and thus can 3069e22bee78STejun Heo * guarantee sched callbacks see the rogue flag. This is 3070e22bee78STejun Heo * necessary as scheduler callbacks may be invoked from other 3071e22bee78STejun Heo * cpus. 3072e22bee78STejun Heo */ 3073e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3074e22bee78STejun Heo schedule(); 3075e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3076e22bee78STejun Heo 3077e22bee78STejun Heo /* 3078cb444766STejun Heo * Sched callbacks are disabled now. Zap nr_running. After 3079cb444766STejun Heo * this, nr_running stays zero and need_more_worker() and 3080cb444766STejun Heo * keep_working() are always true as long as the worklist is 3081cb444766STejun Heo * not empty. 3082e22bee78STejun Heo */ 3083cb444766STejun Heo atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); 3084e22bee78STejun Heo 3085e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3086e22bee78STejun Heo del_timer_sync(&gcwq->idle_timer); 3087e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3088e22bee78STejun Heo 3089e22bee78STejun Heo /* 3090db7bccf4STejun Heo * We're now in charge. Notify and proceed to drain. We need 3091db7bccf4STejun Heo * to keep the gcwq running during the whole CPU down 3092db7bccf4STejun Heo * procedure as other cpu hotunplug callbacks may need to 3093db7bccf4STejun Heo * flush currently running tasks. 3094db7bccf4STejun Heo */ 3095db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_IN_CHARGE; 3096db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3097db7bccf4STejun Heo 3098db7bccf4STejun Heo /* 3099db7bccf4STejun Heo * The original cpu is in the process of dying and may go away 3100db7bccf4STejun Heo * anytime now. When that happens, we and all workers would 3101e22bee78STejun Heo * be migrated to other cpus. Try draining any left work. We 3102e22bee78STejun Heo * want to get it over with ASAP - spam rescuers, wake up as 3103e22bee78STejun Heo * many idlers as necessary and create new ones till the 3104e22bee78STejun Heo * worklist is empty. Note that if the gcwq is frozen, there 3105e22bee78STejun Heo * may be frozen works in freezeable cwqs. Don't declare 3106e22bee78STejun Heo * completion while frozen. 3107db7bccf4STejun Heo */ 3108db7bccf4STejun Heo while (gcwq->nr_workers != gcwq->nr_idle || 3109db7bccf4STejun Heo gcwq->flags & GCWQ_FREEZING || 3110db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_IN_CHARGE) { 3111e22bee78STejun Heo int nr_works = 0; 3112e22bee78STejun Heo 3113e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) { 3114e22bee78STejun Heo send_mayday(work); 3115e22bee78STejun Heo nr_works++; 3116e22bee78STejun Heo } 3117e22bee78STejun Heo 3118e22bee78STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) { 3119e22bee78STejun Heo if (!nr_works--) 3120e22bee78STejun Heo break; 3121e22bee78STejun Heo wake_up_process(worker->task); 3122e22bee78STejun Heo } 3123e22bee78STejun Heo 3124e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 3125e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3126e22bee78STejun Heo worker = create_worker(gcwq, false); 3127e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3128e22bee78STejun Heo if (worker) { 3129cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3130e22bee78STejun Heo start_worker(worker); 3131e22bee78STejun Heo } 3132e22bee78STejun Heo } 3133e22bee78STejun Heo 3134db7bccf4STejun Heo /* give a breather */ 3135db7bccf4STejun Heo if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) 3136db7bccf4STejun Heo break; 3137db7bccf4STejun Heo } 3138db7bccf4STejun Heo 3139e22bee78STejun Heo /* 3140e22bee78STejun Heo * Either all works have been scheduled and cpu is down, or 3141e22bee78STejun Heo * cpu down has already been canceled. Wait for and butcher 3142e22bee78STejun Heo * all workers till we're canceled. 3143e22bee78STejun Heo */ 3144e22bee78STejun Heo do { 3145e22bee78STejun Heo rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); 3146e22bee78STejun Heo while (!list_empty(&gcwq->idle_list)) 3147e22bee78STejun Heo destroy_worker(list_first_entry(&gcwq->idle_list, 3148e22bee78STejun Heo struct worker, entry)); 3149e22bee78STejun Heo } while (gcwq->nr_workers && rc >= 0); 3150e22bee78STejun Heo 3151e22bee78STejun Heo /* 3152e22bee78STejun Heo * At this point, either draining has completed and no worker 3153e22bee78STejun Heo * is left, or cpu down has been canceled or the cpu is being 3154e22bee78STejun Heo * brought back up. There shouldn't be any idle one left. 3155e22bee78STejun Heo * Tell the remaining busy ones to rebind once it finishes the 3156e22bee78STejun Heo * currently scheduled works by scheduling the rebind_work. 3157e22bee78STejun Heo */ 3158e22bee78STejun Heo WARN_ON(!list_empty(&gcwq->idle_list)); 3159e22bee78STejun Heo 3160e22bee78STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 3161e22bee78STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 3162e22bee78STejun Heo 3163e22bee78STejun Heo /* 3164e22bee78STejun Heo * Rebind_work may race with future cpu hotplug 3165e22bee78STejun Heo * operations. Use a separate flag to mark that 3166e22bee78STejun Heo * rebinding is scheduled. 3167e22bee78STejun Heo */ 3168cb444766STejun Heo worker->flags |= WORKER_REBIND; 3169cb444766STejun Heo worker->flags &= ~WORKER_ROGUE; 3170e22bee78STejun Heo 3171e22bee78STejun Heo /* queue rebind_work, wq doesn't matter, use the default one */ 3172e22bee78STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 3173e22bee78STejun Heo work_data_bits(rebind_work))) 3174e22bee78STejun Heo continue; 3175e22bee78STejun Heo 3176e22bee78STejun Heo debug_work_activate(rebind_work); 3177d320c038STejun Heo insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, 3178e22bee78STejun Heo worker->scheduled.next, 3179e22bee78STejun Heo work_color_to_flags(WORK_NO_COLOR)); 3180e22bee78STejun Heo } 3181e22bee78STejun Heo 3182e22bee78STejun Heo /* relinquish manager role */ 3183e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 3184e22bee78STejun Heo 3185db7bccf4STejun Heo /* notify completion */ 3186db7bccf4STejun Heo gcwq->trustee = NULL; 3187db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3188db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3189db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3190db7bccf4STejun Heo return 0; 3191db7bccf4STejun Heo } 3192db7bccf4STejun Heo 3193db7bccf4STejun Heo /** 3194db7bccf4STejun Heo * wait_trustee_state - wait for trustee to enter the specified state 3195db7bccf4STejun Heo * @gcwq: gcwq the trustee of interest belongs to 3196db7bccf4STejun Heo * @state: target state to wait for 3197db7bccf4STejun Heo * 3198db7bccf4STejun Heo * Wait for the trustee to reach @state. DONE is already matched. 3199db7bccf4STejun Heo * 3200db7bccf4STejun Heo * CONTEXT: 3201db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3202db7bccf4STejun Heo * multiple times. To be used by cpu_callback. 3203db7bccf4STejun Heo */ 3204db7bccf4STejun Heo static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) 3205db7bccf4STejun Heo { 3206db7bccf4STejun Heo if (!(gcwq->trustee_state == state || 3207db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE)) { 3208db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3209db7bccf4STejun Heo __wait_event(gcwq->trustee_wait, 3210db7bccf4STejun Heo gcwq->trustee_state == state || 3211db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE); 3212db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3213db7bccf4STejun Heo } 3214db7bccf4STejun Heo } 3215db7bccf4STejun Heo 32169c7b216dSChandra Seetharaman static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 32171da177e4SLinus Torvalds unsigned long action, 32181da177e4SLinus Torvalds void *hcpu) 32191da177e4SLinus Torvalds { 32203af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 3221db7bccf4STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3222db7bccf4STejun Heo struct task_struct *new_trustee = NULL; 3223e22bee78STejun Heo struct worker *uninitialized_var(new_worker); 3224db7bccf4STejun Heo unsigned long flags; 32251da177e4SLinus Torvalds 32268bb78442SRafael J. Wysocki action &= ~CPU_TASKS_FROZEN; 32278bb78442SRafael J. Wysocki 3228db7bccf4STejun Heo switch (action) { 3229db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3230db7bccf4STejun Heo new_trustee = kthread_create(trustee_thread, gcwq, 3231db7bccf4STejun Heo "workqueue_trustee/%d\n", cpu); 3232db7bccf4STejun Heo if (IS_ERR(new_trustee)) 3233db7bccf4STejun Heo return notifier_from_errno(PTR_ERR(new_trustee)); 3234db7bccf4STejun Heo kthread_bind(new_trustee, cpu); 3235e22bee78STejun Heo /* fall through */ 3236e22bee78STejun Heo case CPU_UP_PREPARE: 3237e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3238e22bee78STejun Heo new_worker = create_worker(gcwq, false); 3239e22bee78STejun Heo if (!new_worker) { 3240e22bee78STejun Heo if (new_trustee) 3241e22bee78STejun Heo kthread_stop(new_trustee); 3242e22bee78STejun Heo return NOTIFY_BAD; 3243e22bee78STejun Heo } 3244db7bccf4STejun Heo } 32451537663fSTejun Heo 3246db7bccf4STejun Heo /* some are called w/ irq disabled, don't disturb irq status */ 3247db7bccf4STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 32483af24433SOleg Nesterov 32493af24433SOleg Nesterov switch (action) { 3250db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3251db7bccf4STejun Heo /* initialize trustee and tell it to acquire the gcwq */ 3252db7bccf4STejun Heo BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); 3253db7bccf4STejun Heo gcwq->trustee = new_trustee; 3254db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_START; 3255db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3256db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); 3257e22bee78STejun Heo /* fall through */ 3258e22bee78STejun Heo case CPU_UP_PREPARE: 3259e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3260e22bee78STejun Heo gcwq->first_idle = new_worker; 3261e22bee78STejun Heo break; 3262e22bee78STejun Heo 3263e22bee78STejun Heo case CPU_DYING: 3264e22bee78STejun Heo /* 3265e22bee78STejun Heo * Before this, the trustee and all workers except for 3266e22bee78STejun Heo * the ones which are still executing works from 3267e22bee78STejun Heo * before the last CPU down must be on the cpu. After 3268e22bee78STejun Heo * this, they'll all be diasporas. 3269e22bee78STejun Heo */ 3270e22bee78STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 3271db7bccf4STejun Heo break; 3272db7bccf4STejun Heo 32733da1c84cSOleg Nesterov case CPU_POST_DEAD: 3274db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_BUTCHER; 3275e22bee78STejun Heo /* fall through */ 3276e22bee78STejun Heo case CPU_UP_CANCELED: 3277e22bee78STejun Heo destroy_worker(gcwq->first_idle); 3278e22bee78STejun Heo gcwq->first_idle = NULL; 3279db7bccf4STejun Heo break; 3280db7bccf4STejun Heo 3281db7bccf4STejun Heo case CPU_DOWN_FAILED: 3282db7bccf4STejun Heo case CPU_ONLINE: 3283e22bee78STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3284db7bccf4STejun Heo if (gcwq->trustee_state != TRUSTEE_DONE) { 3285db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_RELEASE; 3286db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3287db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_DONE); 3288db7bccf4STejun Heo } 3289db7bccf4STejun Heo 3290e22bee78STejun Heo /* 3291e22bee78STejun Heo * Trustee is done and there might be no worker left. 3292e22bee78STejun Heo * Put the first_idle in and request a real manager to 3293e22bee78STejun Heo * take a look. 3294e22bee78STejun Heo */ 3295e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3296e22bee78STejun Heo kthread_bind(gcwq->first_idle->task, cpu); 3297e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3298e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 3299e22bee78STejun Heo start_worker(gcwq->first_idle); 3300e22bee78STejun Heo gcwq->first_idle = NULL; 33011da177e4SLinus Torvalds break; 33021da177e4SLinus Torvalds } 3303db7bccf4STejun Heo 3304db7bccf4STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 33051da177e4SLinus Torvalds 33061537663fSTejun Heo return notifier_from_errno(0); 33071da177e4SLinus Torvalds } 33081da177e4SLinus Torvalds 33092d3854a3SRusty Russell #ifdef CONFIG_SMP 33108ccad40dSRusty Russell 33112d3854a3SRusty Russell struct work_for_cpu { 33126b44003eSAndrew Morton struct completion completion; 33132d3854a3SRusty Russell long (*fn)(void *); 33142d3854a3SRusty Russell void *arg; 33152d3854a3SRusty Russell long ret; 33162d3854a3SRusty Russell }; 33172d3854a3SRusty Russell 33186b44003eSAndrew Morton static int do_work_for_cpu(void *_wfc) 33192d3854a3SRusty Russell { 33206b44003eSAndrew Morton struct work_for_cpu *wfc = _wfc; 33212d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 33226b44003eSAndrew Morton complete(&wfc->completion); 33236b44003eSAndrew Morton return 0; 33242d3854a3SRusty Russell } 33252d3854a3SRusty Russell 33262d3854a3SRusty Russell /** 33272d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 33282d3854a3SRusty Russell * @cpu: the cpu to run on 33292d3854a3SRusty Russell * @fn: the function to run 33302d3854a3SRusty Russell * @arg: the function arg 33312d3854a3SRusty Russell * 333231ad9081SRusty Russell * This will return the value @fn returns. 333331ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 33346b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 33352d3854a3SRusty Russell */ 33362d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 33372d3854a3SRusty Russell { 33386b44003eSAndrew Morton struct task_struct *sub_thread; 33396b44003eSAndrew Morton struct work_for_cpu wfc = { 33406b44003eSAndrew Morton .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), 33416b44003eSAndrew Morton .fn = fn, 33426b44003eSAndrew Morton .arg = arg, 33436b44003eSAndrew Morton }; 33442d3854a3SRusty Russell 33456b44003eSAndrew Morton sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); 33466b44003eSAndrew Morton if (IS_ERR(sub_thread)) 33476b44003eSAndrew Morton return PTR_ERR(sub_thread); 33486b44003eSAndrew Morton kthread_bind(sub_thread, cpu); 33496b44003eSAndrew Morton wake_up_process(sub_thread); 33506b44003eSAndrew Morton wait_for_completion(&wfc.completion); 33512d3854a3SRusty Russell return wfc.ret; 33522d3854a3SRusty Russell } 33532d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 33542d3854a3SRusty Russell #endif /* CONFIG_SMP */ 33552d3854a3SRusty Russell 3356a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3357a0a1a5fdSTejun Heo 3358a0a1a5fdSTejun Heo /** 3359a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3360a0a1a5fdSTejun Heo * 3361a0a1a5fdSTejun Heo * Start freezing workqueues. After this function returns, all 3362a0a1a5fdSTejun Heo * freezeable workqueues will queue new works to their frozen_works 33637e11629dSTejun Heo * list instead of gcwq->worklist. 3364a0a1a5fdSTejun Heo * 3365a0a1a5fdSTejun Heo * CONTEXT: 33668b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3367a0a1a5fdSTejun Heo */ 3368a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3369a0a1a5fdSTejun Heo { 3370a0a1a5fdSTejun Heo unsigned int cpu; 3371a0a1a5fdSTejun Heo 3372a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3373a0a1a5fdSTejun Heo 3374a0a1a5fdSTejun Heo BUG_ON(workqueue_freezing); 3375a0a1a5fdSTejun Heo workqueue_freezing = true; 3376a0a1a5fdSTejun Heo 3377f3421797STejun Heo for_each_gcwq_cpu(cpu) { 33788b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3379bdbc5dd7STejun Heo struct workqueue_struct *wq; 33808b03ae3cSTejun Heo 33818b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 33828b03ae3cSTejun Heo 3383db7bccf4STejun Heo BUG_ON(gcwq->flags & GCWQ_FREEZING); 3384db7bccf4STejun Heo gcwq->flags |= GCWQ_FREEZING; 3385db7bccf4STejun Heo 3386a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3387a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3388a0a1a5fdSTejun Heo 3389f3421797STejun Heo if (cwq && wq->flags & WQ_FREEZEABLE) 3390a0a1a5fdSTejun Heo cwq->max_active = 0; 3391a0a1a5fdSTejun Heo } 33928b03ae3cSTejun Heo 33938b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3394a0a1a5fdSTejun Heo } 3395a0a1a5fdSTejun Heo 3396a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3397a0a1a5fdSTejun Heo } 3398a0a1a5fdSTejun Heo 3399a0a1a5fdSTejun Heo /** 3400a0a1a5fdSTejun Heo * freeze_workqueues_busy - are freezeable workqueues still busy? 3401a0a1a5fdSTejun Heo * 3402a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3403a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3404a0a1a5fdSTejun Heo * 3405a0a1a5fdSTejun Heo * CONTEXT: 3406a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3407a0a1a5fdSTejun Heo * 3408a0a1a5fdSTejun Heo * RETURNS: 3409a0a1a5fdSTejun Heo * %true if some freezeable workqueues are still busy. %false if 3410a0a1a5fdSTejun Heo * freezing is complete. 3411a0a1a5fdSTejun Heo */ 3412a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3413a0a1a5fdSTejun Heo { 3414a0a1a5fdSTejun Heo unsigned int cpu; 3415a0a1a5fdSTejun Heo bool busy = false; 3416a0a1a5fdSTejun Heo 3417a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3418a0a1a5fdSTejun Heo 3419a0a1a5fdSTejun Heo BUG_ON(!workqueue_freezing); 3420a0a1a5fdSTejun Heo 3421f3421797STejun Heo for_each_gcwq_cpu(cpu) { 3422bdbc5dd7STejun Heo struct workqueue_struct *wq; 3423a0a1a5fdSTejun Heo /* 3424a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3425a0a1a5fdSTejun Heo * to peek without lock. 3426a0a1a5fdSTejun Heo */ 3427a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3428a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3429a0a1a5fdSTejun Heo 3430f3421797STejun Heo if (!cwq || !(wq->flags & WQ_FREEZEABLE)) 3431a0a1a5fdSTejun Heo continue; 3432a0a1a5fdSTejun Heo 3433a0a1a5fdSTejun Heo BUG_ON(cwq->nr_active < 0); 3434a0a1a5fdSTejun Heo if (cwq->nr_active) { 3435a0a1a5fdSTejun Heo busy = true; 3436a0a1a5fdSTejun Heo goto out_unlock; 3437a0a1a5fdSTejun Heo } 3438a0a1a5fdSTejun Heo } 3439a0a1a5fdSTejun Heo } 3440a0a1a5fdSTejun Heo out_unlock: 3441a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3442a0a1a5fdSTejun Heo return busy; 3443a0a1a5fdSTejun Heo } 3444a0a1a5fdSTejun Heo 3445a0a1a5fdSTejun Heo /** 3446a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3447a0a1a5fdSTejun Heo * 3448a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 34497e11629dSTejun Heo * frozen works are transferred to their respective gcwq worklists. 3450a0a1a5fdSTejun Heo * 3451a0a1a5fdSTejun Heo * CONTEXT: 34528b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3453a0a1a5fdSTejun Heo */ 3454a0a1a5fdSTejun Heo void thaw_workqueues(void) 3455a0a1a5fdSTejun Heo { 3456a0a1a5fdSTejun Heo unsigned int cpu; 3457a0a1a5fdSTejun Heo 3458a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3459a0a1a5fdSTejun Heo 3460a0a1a5fdSTejun Heo if (!workqueue_freezing) 3461a0a1a5fdSTejun Heo goto out_unlock; 3462a0a1a5fdSTejun Heo 3463f3421797STejun Heo for_each_gcwq_cpu(cpu) { 34648b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3465bdbc5dd7STejun Heo struct workqueue_struct *wq; 34668b03ae3cSTejun Heo 34678b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 34688b03ae3cSTejun Heo 3469db7bccf4STejun Heo BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); 3470db7bccf4STejun Heo gcwq->flags &= ~GCWQ_FREEZING; 3471db7bccf4STejun Heo 3472a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3473a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3474a0a1a5fdSTejun Heo 3475f3421797STejun Heo if (!cwq || !(wq->flags & WQ_FREEZEABLE)) 3476a0a1a5fdSTejun Heo continue; 3477a0a1a5fdSTejun Heo 3478a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 3479a0a1a5fdSTejun Heo cwq->max_active = wq->saved_max_active; 3480a0a1a5fdSTejun Heo 3481a0a1a5fdSTejun Heo while (!list_empty(&cwq->delayed_works) && 3482a0a1a5fdSTejun Heo cwq->nr_active < cwq->max_active) 3483a0a1a5fdSTejun Heo cwq_activate_first_delayed(cwq); 3484a0a1a5fdSTejun Heo } 34858b03ae3cSTejun Heo 3486e22bee78STejun Heo wake_up_worker(gcwq); 3487e22bee78STejun Heo 34888b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3489a0a1a5fdSTejun Heo } 3490a0a1a5fdSTejun Heo 3491a0a1a5fdSTejun Heo workqueue_freezing = false; 3492a0a1a5fdSTejun Heo out_unlock: 3493a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3494a0a1a5fdSTejun Heo } 3495a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3496a0a1a5fdSTejun Heo 3497c12920d1SOleg Nesterov void __init init_workqueues(void) 34981da177e4SLinus Torvalds { 3499c34056a3STejun Heo unsigned int cpu; 3500c8e55f36STejun Heo int i; 3501c34056a3STejun Heo 3502db7bccf4STejun Heo hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); 35038b03ae3cSTejun Heo 35048b03ae3cSTejun Heo /* initialize gcwqs */ 3505f3421797STejun Heo for_each_gcwq_cpu(cpu) { 35068b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 35078b03ae3cSTejun Heo 35088b03ae3cSTejun Heo spin_lock_init(&gcwq->lock); 35097e11629dSTejun Heo INIT_LIST_HEAD(&gcwq->worklist); 35108b03ae3cSTejun Heo gcwq->cpu = cpu; 3511f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 3512f3421797STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 35138b03ae3cSTejun Heo 3514c8e55f36STejun Heo INIT_LIST_HEAD(&gcwq->idle_list); 3515c8e55f36STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) 3516c8e55f36STejun Heo INIT_HLIST_HEAD(&gcwq->busy_hash[i]); 3517c8e55f36STejun Heo 3518e22bee78STejun Heo init_timer_deferrable(&gcwq->idle_timer); 3519e22bee78STejun Heo gcwq->idle_timer.function = idle_worker_timeout; 3520e22bee78STejun Heo gcwq->idle_timer.data = (unsigned long)gcwq; 3521e22bee78STejun Heo 3522e22bee78STejun Heo setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, 3523e22bee78STejun Heo (unsigned long)gcwq); 3524e22bee78STejun Heo 35258b03ae3cSTejun Heo ida_init(&gcwq->worker_ida); 3526db7bccf4STejun Heo 3527db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3528db7bccf4STejun Heo init_waitqueue_head(&gcwq->trustee_wait); 35298b03ae3cSTejun Heo } 35308b03ae3cSTejun Heo 3531e22bee78STejun Heo /* create the initial worker */ 3532f3421797STejun Heo for_each_online_gcwq_cpu(cpu) { 3533e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3534e22bee78STejun Heo struct worker *worker; 3535e22bee78STejun Heo 3536e22bee78STejun Heo worker = create_worker(gcwq, true); 3537e22bee78STejun Heo BUG_ON(!worker); 3538e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3539e22bee78STejun Heo start_worker(worker); 3540e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3541e22bee78STejun Heo } 3542e22bee78STejun Heo 3543d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 3544d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3545d320c038STejun Heo system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); 3546f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3547f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 3548d320c038STejun Heo BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq); 35491da177e4SLinus Torvalds } 3550