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 38e36c886aSArjan van de Ven #define CREATE_TRACE_POINTS 39e36c886aSArjan van de Ven #include <trace/events/workqueue.h> 40e36c886aSArjan van de Ven 41e22bee78STejun Heo #include "workqueue_sched.h" 421da177e4SLinus Torvalds 43c8e55f36STejun Heo enum { 44db7bccf4STejun Heo /* global_cwq flags */ 45e22bee78STejun Heo GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ 46e22bee78STejun Heo GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */ 47e22bee78STejun Heo GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 48db7bccf4STejun Heo GCWQ_FREEZING = 1 << 3, /* freeze in progress */ 49649027d7STejun Heo GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */ 50db7bccf4STejun Heo 51c8e55f36STejun Heo /* worker flags */ 52c8e55f36STejun Heo WORKER_STARTED = 1 << 0, /* started */ 53c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 54c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 55e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 56db7bccf4STejun Heo WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ 57e22bee78STejun Heo WORKER_REBIND = 1 << 5, /* mom is home, come back */ 58fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 59f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 60e22bee78STejun Heo 61fb0e7bebSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | 62f3421797STejun Heo WORKER_CPU_INTENSIVE | WORKER_UNBOUND, 63db7bccf4STejun Heo 64db7bccf4STejun Heo /* gcwq->trustee_state */ 65db7bccf4STejun Heo TRUSTEE_START = 0, /* start */ 66db7bccf4STejun Heo TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ 67db7bccf4STejun Heo TRUSTEE_BUTCHER = 2, /* butcher workers */ 68db7bccf4STejun Heo TRUSTEE_RELEASE = 3, /* release workers */ 69db7bccf4STejun Heo TRUSTEE_DONE = 4, /* trustee is done */ 70c8e55f36STejun Heo 71c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 72c8e55f36STejun Heo BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, 73c8e55f36STejun Heo BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, 74db7bccf4STejun Heo 75e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 76e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 77e22bee78STejun Heo 78e22bee78STejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */ 79e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 80e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 81db7bccf4STejun Heo TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ 821da177e4SLinus Torvalds 831da177e4SLinus Torvalds /* 84e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 85e22bee78STejun Heo * all cpus. Give -20. 86e22bee78STejun Heo */ 87e22bee78STejun Heo RESCUER_NICE_LEVEL = -20, 88c8e55f36STejun Heo }; 89c8e55f36STejun Heo 901da177e4SLinus Torvalds /* 914690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 924690c4abSTejun Heo * 934690c4abSTejun Heo * I: Set during initialization and read-only afterwards. 944690c4abSTejun Heo * 95e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 96e22bee78STejun Heo * only be modified and accessed from the local cpu. 97e22bee78STejun Heo * 988b03ae3cSTejun Heo * L: gcwq->lock protected. Access with gcwq->lock held. 994690c4abSTejun Heo * 100e22bee78STejun Heo * X: During normal operation, modification requires gcwq->lock and 101e22bee78STejun Heo * should be done only from local cpu. Either disabling preemption 102e22bee78STejun Heo * on local cpu or grabbing gcwq->lock is enough for read access. 103f3421797STejun Heo * If GCWQ_DISASSOCIATED is set, it's identical to L. 104e22bee78STejun Heo * 10573f53c4aSTejun Heo * F: wq->flush_mutex protected. 10673f53c4aSTejun Heo * 1074690c4abSTejun Heo * W: workqueue_lock protected. 1084690c4abSTejun Heo */ 1094690c4abSTejun Heo 1108b03ae3cSTejun Heo struct global_cwq; 111c34056a3STejun Heo 112e22bee78STejun Heo /* 113e22bee78STejun Heo * The poor guys doing the actual heavy lifting. All on-duty workers 114e22bee78STejun Heo * are either serving the manager role, on idle list or on busy hash. 115e22bee78STejun Heo */ 116c34056a3STejun Heo struct worker { 117c8e55f36STejun Heo /* on idle list while idle, on busy hash table while busy */ 118c8e55f36STejun Heo union { 119c8e55f36STejun Heo struct list_head entry; /* L: while idle */ 120c8e55f36STejun Heo struct hlist_node hentry; /* L: while busy */ 121c8e55f36STejun Heo }; 122c8e55f36STejun Heo 123c34056a3STejun Heo struct work_struct *current_work; /* L: work being processed */ 1248cca0eeaSTejun Heo struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ 125affee4b2STejun Heo struct list_head scheduled; /* L: scheduled works */ 126c34056a3STejun Heo struct task_struct *task; /* I: worker task */ 1278b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 128e22bee78STejun Heo /* 64 bytes boundary on 64bit, 32 on 32bit */ 129e22bee78STejun Heo unsigned long last_active; /* L: last active timestamp */ 130e22bee78STejun Heo unsigned int flags; /* X: flags */ 131c34056a3STejun Heo int id; /* I: worker id */ 132e22bee78STejun Heo struct work_struct rebind_work; /* L: rebind worker to cpu */ 133c34056a3STejun Heo }; 134c34056a3STejun Heo 1354690c4abSTejun Heo /* 136e22bee78STejun Heo * Global per-cpu workqueue. There's one and only one for each cpu 137e22bee78STejun Heo * and all works are queued and processed here regardless of their 138e22bee78STejun Heo * target workqueues. 1398b03ae3cSTejun Heo */ 1408b03ae3cSTejun Heo struct global_cwq { 1418b03ae3cSTejun Heo spinlock_t lock; /* the gcwq lock */ 1427e11629dSTejun Heo struct list_head worklist; /* L: list of pending works */ 1438b03ae3cSTejun Heo unsigned int cpu; /* I: the associated cpu */ 144db7bccf4STejun Heo unsigned int flags; /* L: GCWQ_* flags */ 145c8e55f36STejun Heo 146c8e55f36STejun Heo int nr_workers; /* L: total number of workers */ 147c8e55f36STejun Heo int nr_idle; /* L: currently idle ones */ 148c8e55f36STejun Heo 149c8e55f36STejun Heo /* workers are chained either in the idle_list or busy_hash */ 150e22bee78STejun Heo struct list_head idle_list; /* X: list of idle workers */ 151c8e55f36STejun Heo struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; 152c8e55f36STejun Heo /* L: hash of busy workers */ 153c8e55f36STejun Heo 154e22bee78STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 155e22bee78STejun Heo struct timer_list mayday_timer; /* L: SOS timer for dworkers */ 156e22bee78STejun Heo 1578b03ae3cSTejun Heo struct ida worker_ida; /* L: for worker IDs */ 158db7bccf4STejun Heo 159db7bccf4STejun Heo struct task_struct *trustee; /* L: for gcwq shutdown */ 160db7bccf4STejun Heo unsigned int trustee_state; /* L: trustee state */ 161db7bccf4STejun Heo wait_queue_head_t trustee_wait; /* trustee wait */ 162e22bee78STejun Heo struct worker *first_idle; /* L: first idle worker */ 1638b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1648b03ae3cSTejun Heo 1658b03ae3cSTejun Heo /* 166502ca9d8STejun Heo * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of 1670f900049STejun Heo * work_struct->data are used for flags and thus cwqs need to be 1680f900049STejun Heo * aligned at two's power of the number of flag bits. 1691da177e4SLinus Torvalds */ 1701da177e4SLinus Torvalds struct cpu_workqueue_struct { 1718b03ae3cSTejun Heo struct global_cwq *gcwq; /* I: the associated gcwq */ 1724690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 17373f53c4aSTejun Heo int work_color; /* L: current color */ 17473f53c4aSTejun Heo int flush_color; /* L: flushing color */ 17573f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 17673f53c4aSTejun Heo /* L: nr of in_flight works */ 1771e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 178a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 1791e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 1800f900049STejun Heo }; 1811da177e4SLinus Torvalds 1821da177e4SLinus Torvalds /* 18373f53c4aSTejun Heo * Structure used to wait for workqueue flush. 18473f53c4aSTejun Heo */ 18573f53c4aSTejun Heo struct wq_flusher { 18673f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 18773f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 18873f53c4aSTejun Heo struct completion done; /* flush completion */ 18973f53c4aSTejun Heo }; 1901da177e4SLinus Torvalds 19173f53c4aSTejun Heo /* 192f2e005aaSTejun Heo * All cpumasks are assumed to be always set on UP and thus can't be 193f2e005aaSTejun Heo * used to determine whether there's something to be done. 194f2e005aaSTejun Heo */ 195f2e005aaSTejun Heo #ifdef CONFIG_SMP 196f2e005aaSTejun Heo typedef cpumask_var_t mayday_mask_t; 197f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) \ 198f2e005aaSTejun Heo cpumask_test_and_set_cpu((cpu), (mask)) 199f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) 200f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) 201f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) alloc_cpumask_var((maskp), (gfp)) 202f2e005aaSTejun Heo #define free_mayday_mask(mask) free_cpumask_var((mask)) 203f2e005aaSTejun Heo #else 204f2e005aaSTejun Heo typedef unsigned long mayday_mask_t; 205f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) 206f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) 207f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) 208f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) true 209f2e005aaSTejun Heo #define free_mayday_mask(mask) do { } while (0) 210f2e005aaSTejun Heo #endif 2111da177e4SLinus Torvalds 2121da177e4SLinus Torvalds /* 2131da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 2141da177e4SLinus Torvalds * per-CPU workqueues: 2151da177e4SLinus Torvalds */ 2161da177e4SLinus Torvalds struct workqueue_struct { 21797e37d7bSTejun Heo unsigned int flags; /* I: WQ_* flags */ 218bdbc5dd7STejun Heo union { 219bdbc5dd7STejun Heo struct cpu_workqueue_struct __percpu *pcpu; 220bdbc5dd7STejun Heo struct cpu_workqueue_struct *single; 221bdbc5dd7STejun Heo unsigned long v; 222bdbc5dd7STejun Heo } cpu_wq; /* I: cwq's */ 2234690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 22473f53c4aSTejun Heo 22573f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 22673f53c4aSTejun Heo int work_color; /* F: current work color */ 22773f53c4aSTejun Heo int flush_color; /* F: current flush color */ 22873f53c4aSTejun Heo atomic_t nr_cwqs_to_flush; /* flush in progress */ 22973f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 23073f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 23173f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 23273f53c4aSTejun Heo 233f2e005aaSTejun Heo mayday_mask_t mayday_mask; /* cpus requesting rescue */ 234e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 235e22bee78STejun Heo 236dcd989cbSTejun Heo int saved_max_active; /* W: saved cwq max_active */ 2374690c4abSTejun Heo const char *name; /* I: workqueue name */ 2384e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2394e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2404e6045f1SJohannes Berg #endif 2411da177e4SLinus Torvalds }; 2421da177e4SLinus Torvalds 243d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 244d320c038STejun Heo struct workqueue_struct *system_long_wq __read_mostly; 245d320c038STejun Heo struct workqueue_struct *system_nrt_wq __read_mostly; 246f3421797STejun Heo struct workqueue_struct *system_unbound_wq __read_mostly; 247d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 248d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 249d320c038STejun Heo EXPORT_SYMBOL_GPL(system_nrt_wq); 250f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 251d320c038STejun Heo 252db7bccf4STejun Heo #define for_each_busy_worker(worker, i, pos, gcwq) \ 253db7bccf4STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ 254db7bccf4STejun Heo hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) 255db7bccf4STejun Heo 256f3421797STejun Heo static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, 257f3421797STejun Heo unsigned int sw) 258f3421797STejun Heo { 259f3421797STejun Heo if (cpu < nr_cpu_ids) { 260f3421797STejun Heo if (sw & 1) { 261f3421797STejun Heo cpu = cpumask_next(cpu, mask); 262f3421797STejun Heo if (cpu < nr_cpu_ids) 263f3421797STejun Heo return cpu; 264f3421797STejun Heo } 265f3421797STejun Heo if (sw & 2) 266f3421797STejun Heo return WORK_CPU_UNBOUND; 267f3421797STejun Heo } 268f3421797STejun Heo return WORK_CPU_NONE; 269f3421797STejun Heo } 270f3421797STejun Heo 271f3421797STejun Heo static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, 272f3421797STejun Heo struct workqueue_struct *wq) 273f3421797STejun Heo { 274f3421797STejun Heo return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); 275f3421797STejun Heo } 276f3421797STejun Heo 27709884951STejun Heo /* 27809884951STejun Heo * CPU iterators 27909884951STejun Heo * 28009884951STejun Heo * An extra gcwq is defined for an invalid cpu number 28109884951STejun Heo * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any 28209884951STejun Heo * specific CPU. The following iterators are similar to 28309884951STejun Heo * for_each_*_cpu() iterators but also considers the unbound gcwq. 28409884951STejun Heo * 28509884951STejun Heo * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND 28609884951STejun Heo * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND 28709884951STejun Heo * for_each_cwq_cpu() : possible CPUs for bound workqueues, 28809884951STejun Heo * WORK_CPU_UNBOUND for unbound workqueues 28909884951STejun Heo */ 290f3421797STejun Heo #define for_each_gcwq_cpu(cpu) \ 291f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ 292f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 293f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) 294f3421797STejun Heo 295f3421797STejun Heo #define for_each_online_gcwq_cpu(cpu) \ 296f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ 297f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 298f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) 299f3421797STejun Heo 300f3421797STejun Heo #define for_each_cwq_cpu(cpu, wq) \ 301f3421797STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ 302f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 303f3421797STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) 304f3421797STejun Heo 305a25909a4SPaul E. McKenney #ifdef CONFIG_LOCKDEP 306a25909a4SPaul E. McKenney /** 307a25909a4SPaul E. McKenney * in_workqueue_context() - in context of specified workqueue? 308a25909a4SPaul E. McKenney * @wq: the workqueue of interest 309a25909a4SPaul E. McKenney * 310a25909a4SPaul E. McKenney * Checks lockdep state to see if the current task is executing from 311a25909a4SPaul E. McKenney * within a workqueue item. This function exists only if lockdep is 312a25909a4SPaul E. McKenney * enabled. 313a25909a4SPaul E. McKenney */ 314a25909a4SPaul E. McKenney int in_workqueue_context(struct workqueue_struct *wq) 315a25909a4SPaul E. McKenney { 316a25909a4SPaul E. McKenney return lock_is_held(&wq->lockdep_map); 317a25909a4SPaul E. McKenney } 318a25909a4SPaul E. McKenney #endif 319a25909a4SPaul E. McKenney 320dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 321dc186ad7SThomas Gleixner 322dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 323dc186ad7SThomas Gleixner 324dc186ad7SThomas Gleixner /* 325dc186ad7SThomas Gleixner * fixup_init is called when: 326dc186ad7SThomas Gleixner * - an active object is initialized 327dc186ad7SThomas Gleixner */ 328dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 329dc186ad7SThomas Gleixner { 330dc186ad7SThomas Gleixner struct work_struct *work = addr; 331dc186ad7SThomas Gleixner 332dc186ad7SThomas Gleixner switch (state) { 333dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 334dc186ad7SThomas Gleixner cancel_work_sync(work); 335dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 336dc186ad7SThomas Gleixner return 1; 337dc186ad7SThomas Gleixner default: 338dc186ad7SThomas Gleixner return 0; 339dc186ad7SThomas Gleixner } 340dc186ad7SThomas Gleixner } 341dc186ad7SThomas Gleixner 342dc186ad7SThomas Gleixner /* 343dc186ad7SThomas Gleixner * fixup_activate is called when: 344dc186ad7SThomas Gleixner * - an active object is activated 345dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 346dc186ad7SThomas Gleixner */ 347dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 348dc186ad7SThomas Gleixner { 349dc186ad7SThomas Gleixner struct work_struct *work = addr; 350dc186ad7SThomas Gleixner 351dc186ad7SThomas Gleixner switch (state) { 352dc186ad7SThomas Gleixner 353dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 354dc186ad7SThomas Gleixner /* 355dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 356dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 357dc186ad7SThomas Gleixner * is tracked in the object tracker. 358dc186ad7SThomas Gleixner */ 35922df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 360dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 361dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 362dc186ad7SThomas Gleixner return 0; 363dc186ad7SThomas Gleixner } 364dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 365dc186ad7SThomas Gleixner return 0; 366dc186ad7SThomas Gleixner 367dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 368dc186ad7SThomas Gleixner WARN_ON(1); 369dc186ad7SThomas Gleixner 370dc186ad7SThomas Gleixner default: 371dc186ad7SThomas Gleixner return 0; 372dc186ad7SThomas Gleixner } 373dc186ad7SThomas Gleixner } 374dc186ad7SThomas Gleixner 375dc186ad7SThomas Gleixner /* 376dc186ad7SThomas Gleixner * fixup_free is called when: 377dc186ad7SThomas Gleixner * - an active object is freed 378dc186ad7SThomas Gleixner */ 379dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 380dc186ad7SThomas Gleixner { 381dc186ad7SThomas Gleixner struct work_struct *work = addr; 382dc186ad7SThomas Gleixner 383dc186ad7SThomas Gleixner switch (state) { 384dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 385dc186ad7SThomas Gleixner cancel_work_sync(work); 386dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 387dc186ad7SThomas Gleixner return 1; 388dc186ad7SThomas Gleixner default: 389dc186ad7SThomas Gleixner return 0; 390dc186ad7SThomas Gleixner } 391dc186ad7SThomas Gleixner } 392dc186ad7SThomas Gleixner 393dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 394dc186ad7SThomas Gleixner .name = "work_struct", 395dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 396dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 397dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 398dc186ad7SThomas Gleixner }; 399dc186ad7SThomas Gleixner 400dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 401dc186ad7SThomas Gleixner { 402dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 403dc186ad7SThomas Gleixner } 404dc186ad7SThomas Gleixner 405dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 406dc186ad7SThomas Gleixner { 407dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 408dc186ad7SThomas Gleixner } 409dc186ad7SThomas Gleixner 410dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 411dc186ad7SThomas Gleixner { 412dc186ad7SThomas Gleixner if (onstack) 413dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 414dc186ad7SThomas Gleixner else 415dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 416dc186ad7SThomas Gleixner } 417dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 418dc186ad7SThomas Gleixner 419dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 420dc186ad7SThomas Gleixner { 421dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 422dc186ad7SThomas Gleixner } 423dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 424dc186ad7SThomas Gleixner 425dc186ad7SThomas Gleixner #else 426dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 427dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 428dc186ad7SThomas Gleixner #endif 429dc186ad7SThomas Gleixner 43095402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 43195402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 4321da177e4SLinus Torvalds static LIST_HEAD(workqueues); 433a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 4341da177e4SLinus Torvalds 43514441960SOleg Nesterov /* 436e22bee78STejun Heo * The almighty global cpu workqueues. nr_running is the only field 437e22bee78STejun Heo * which is expected to be used frequently by other cpus via 438e22bee78STejun Heo * try_to_wake_up(). Put it in a separate cacheline. 43914441960SOleg Nesterov */ 4408b03ae3cSTejun Heo static DEFINE_PER_CPU(struct global_cwq, global_cwq); 441e22bee78STejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); 442f756d5e2SNathan Lynch 443f3421797STejun Heo /* 444f3421797STejun Heo * Global cpu workqueue and nr_running counter for unbound gcwq. The 445f3421797STejun Heo * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its 446f3421797STejun Heo * workers have WORKER_UNBOUND set. 447f3421797STejun Heo */ 448f3421797STejun Heo static struct global_cwq unbound_global_cwq; 449f3421797STejun Heo static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ 450f3421797STejun Heo 451c34056a3STejun Heo static int worker_thread(void *__worker); 4521da177e4SLinus Torvalds 4538b03ae3cSTejun Heo static struct global_cwq *get_gcwq(unsigned int cpu) 4541da177e4SLinus Torvalds { 455f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 4568b03ae3cSTejun Heo return &per_cpu(global_cwq, cpu); 457f3421797STejun Heo else 458f3421797STejun Heo return &unbound_global_cwq; 4591da177e4SLinus Torvalds } 4601da177e4SLinus Torvalds 461e22bee78STejun Heo static atomic_t *get_gcwq_nr_running(unsigned int cpu) 462b1f4ec17SOleg Nesterov { 463f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 464e22bee78STejun Heo return &per_cpu(gcwq_nr_running, cpu); 465f3421797STejun Heo else 466f3421797STejun Heo return &unbound_gcwq_nr_running; 467b1f4ec17SOleg Nesterov } 468b1f4ec17SOleg Nesterov 4694690c4abSTejun Heo static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, 4704690c4abSTejun Heo struct workqueue_struct *wq) 471a848e3b6SOleg Nesterov { 472f3421797STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 473f3421797STejun Heo if (likely(cpu < nr_cpu_ids)) { 474f3421797STejun Heo #ifdef CONFIG_SMP 475bdbc5dd7STejun Heo return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); 476f3421797STejun Heo #else 477f3421797STejun Heo return wq->cpu_wq.single; 478bdbc5dd7STejun Heo #endif 479a848e3b6SOleg Nesterov } 480f3421797STejun Heo } else if (likely(cpu == WORK_CPU_UNBOUND)) 481f3421797STejun Heo return wq->cpu_wq.single; 482f3421797STejun Heo return NULL; 483f3421797STejun Heo } 484a848e3b6SOleg Nesterov 48573f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 48673f53c4aSTejun Heo { 48773f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 48873f53c4aSTejun Heo } 48973f53c4aSTejun Heo 49073f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 49173f53c4aSTejun Heo { 49273f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 49373f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 49473f53c4aSTejun Heo } 49573f53c4aSTejun Heo 49673f53c4aSTejun Heo static int work_next_color(int color) 49773f53c4aSTejun Heo { 49873f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 4991da177e4SLinus Torvalds } 5001da177e4SLinus Torvalds 5014594bf15SDavid Howells /* 502e120153dSTejun Heo * A work's data points to the cwq with WORK_STRUCT_CWQ set while the 503e120153dSTejun Heo * work is on queue. Once execution starts, WORK_STRUCT_CWQ is 504e120153dSTejun Heo * cleared and the work data contains the cpu number it was last on. 5057a22ad75STejun Heo * 5067a22ad75STejun Heo * set_work_{cwq|cpu}() and clear_work_data() can be used to set the 5077a22ad75STejun Heo * cwq, cpu or clear work->data. These functions should only be 5087a22ad75STejun Heo * called while the work is owned - ie. while the PENDING bit is set. 5097a22ad75STejun Heo * 5107a22ad75STejun Heo * get_work_[g]cwq() can be used to obtain the gcwq or cwq 5117a22ad75STejun Heo * corresponding to a work. gcwq is available once the work has been 5127a22ad75STejun Heo * queued anywhere after initialization. cwq is available only from 5137a22ad75STejun Heo * queueing until execution starts. 5144594bf15SDavid Howells */ 5157a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 5167a22ad75STejun Heo unsigned long flags) 5177a22ad75STejun Heo { 5187a22ad75STejun Heo BUG_ON(!work_pending(work)); 5197a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 5207a22ad75STejun Heo } 5217a22ad75STejun Heo 5227a22ad75STejun Heo static void set_work_cwq(struct work_struct *work, 5234690c4abSTejun Heo struct cpu_workqueue_struct *cwq, 5244690c4abSTejun Heo unsigned long extra_flags) 525365970a1SDavid Howells { 5267a22ad75STejun Heo set_work_data(work, (unsigned long)cwq, 527e120153dSTejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); 528365970a1SDavid Howells } 529365970a1SDavid Howells 5307a22ad75STejun Heo static void set_work_cpu(struct work_struct *work, unsigned int cpu) 5314d707b9fSOleg Nesterov { 5327a22ad75STejun Heo set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); 5334d707b9fSOleg Nesterov } 5344d707b9fSOleg Nesterov 5357a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 536365970a1SDavid Howells { 5377a22ad75STejun Heo set_work_data(work, WORK_STRUCT_NO_CPU, 0); 5387a22ad75STejun Heo } 5397a22ad75STejun Heo 5407a22ad75STejun Heo static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) 5417a22ad75STejun Heo { 542e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5437a22ad75STejun Heo 544e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 545e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 546e120153dSTejun Heo else 547e120153dSTejun Heo return NULL; 5487a22ad75STejun Heo } 5497a22ad75STejun Heo 5507a22ad75STejun Heo static struct global_cwq *get_work_gcwq(struct work_struct *work) 5517a22ad75STejun Heo { 552e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5537a22ad75STejun Heo unsigned int cpu; 5547a22ad75STejun Heo 555e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 556e120153dSTejun Heo return ((struct cpu_workqueue_struct *) 557e120153dSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; 5587a22ad75STejun Heo 5597a22ad75STejun Heo cpu = data >> WORK_STRUCT_FLAG_BITS; 560bdbc5dd7STejun Heo if (cpu == WORK_CPU_NONE) 5617a22ad75STejun Heo return NULL; 5627a22ad75STejun Heo 563f3421797STejun Heo BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); 5647a22ad75STejun Heo return get_gcwq(cpu); 565365970a1SDavid Howells } 566365970a1SDavid Howells 567e22bee78STejun Heo /* 568e22bee78STejun Heo * Policy functions. These define the policies on how the global 569e22bee78STejun Heo * worker pool is managed. Unless noted otherwise, these functions 570e22bee78STejun Heo * assume that they're being called with gcwq->lock held. 571e22bee78STejun Heo */ 572e22bee78STejun Heo 573649027d7STejun Heo static bool __need_more_worker(struct global_cwq *gcwq) 574649027d7STejun Heo { 575649027d7STejun Heo return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || 576649027d7STejun Heo gcwq->flags & GCWQ_HIGHPRI_PENDING; 577649027d7STejun Heo } 578649027d7STejun Heo 579e22bee78STejun Heo /* 580e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 581e22bee78STejun Heo * running workers. 582e22bee78STejun Heo */ 583e22bee78STejun Heo static bool need_more_worker(struct global_cwq *gcwq) 584e22bee78STejun Heo { 585649027d7STejun Heo return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); 586e22bee78STejun Heo } 587e22bee78STejun Heo 588e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 589e22bee78STejun Heo static bool may_start_working(struct global_cwq *gcwq) 590e22bee78STejun Heo { 591e22bee78STejun Heo return gcwq->nr_idle; 592e22bee78STejun Heo } 593e22bee78STejun Heo 594e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 595e22bee78STejun Heo static bool keep_working(struct global_cwq *gcwq) 596e22bee78STejun Heo { 597e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 598e22bee78STejun Heo 599e22bee78STejun Heo return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1; 600e22bee78STejun Heo } 601e22bee78STejun Heo 602e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 603e22bee78STejun Heo static bool need_to_create_worker(struct global_cwq *gcwq) 604e22bee78STejun Heo { 605e22bee78STejun Heo return need_more_worker(gcwq) && !may_start_working(gcwq); 606e22bee78STejun Heo } 607e22bee78STejun Heo 608e22bee78STejun Heo /* Do I need to be the manager? */ 609e22bee78STejun Heo static bool need_to_manage_workers(struct global_cwq *gcwq) 610e22bee78STejun Heo { 611e22bee78STejun Heo return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; 612e22bee78STejun Heo } 613e22bee78STejun Heo 614e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 615e22bee78STejun Heo static bool too_many_workers(struct global_cwq *gcwq) 616e22bee78STejun Heo { 617e22bee78STejun Heo bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; 618e22bee78STejun Heo int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ 619e22bee78STejun Heo int nr_busy = gcwq->nr_workers - nr_idle; 620e22bee78STejun Heo 621e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 622e22bee78STejun Heo } 623e22bee78STejun Heo 624e22bee78STejun Heo /* 625e22bee78STejun Heo * Wake up functions. 626e22bee78STejun Heo */ 627e22bee78STejun Heo 6287e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 6297e11629dSTejun Heo static struct worker *first_worker(struct global_cwq *gcwq) 6307e11629dSTejun Heo { 6317e11629dSTejun Heo if (unlikely(list_empty(&gcwq->idle_list))) 6327e11629dSTejun Heo return NULL; 6337e11629dSTejun Heo 6347e11629dSTejun Heo return list_first_entry(&gcwq->idle_list, struct worker, entry); 6357e11629dSTejun Heo } 6367e11629dSTejun Heo 6377e11629dSTejun Heo /** 6387e11629dSTejun Heo * wake_up_worker - wake up an idle worker 6397e11629dSTejun Heo * @gcwq: gcwq to wake worker for 6407e11629dSTejun Heo * 6417e11629dSTejun Heo * Wake up the first idle worker of @gcwq. 6427e11629dSTejun Heo * 6437e11629dSTejun Heo * CONTEXT: 6447e11629dSTejun Heo * spin_lock_irq(gcwq->lock). 6457e11629dSTejun Heo */ 6467e11629dSTejun Heo static void wake_up_worker(struct global_cwq *gcwq) 6477e11629dSTejun Heo { 6487e11629dSTejun Heo struct worker *worker = first_worker(gcwq); 6497e11629dSTejun Heo 6507e11629dSTejun Heo if (likely(worker)) 6517e11629dSTejun Heo wake_up_process(worker->task); 6527e11629dSTejun Heo } 6537e11629dSTejun Heo 6544690c4abSTejun Heo /** 655e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 656e22bee78STejun Heo * @task: task waking up 657e22bee78STejun Heo * @cpu: CPU @task is waking up to 658e22bee78STejun Heo * 659e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 660e22bee78STejun Heo * being awoken. 661e22bee78STejun Heo * 662e22bee78STejun Heo * CONTEXT: 663e22bee78STejun Heo * spin_lock_irq(rq->lock) 664e22bee78STejun Heo */ 665e22bee78STejun Heo void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) 666e22bee78STejun Heo { 667e22bee78STejun Heo struct worker *worker = kthread_data(task); 668e22bee78STejun Heo 669e22bee78STejun Heo if (likely(!(worker->flags & WORKER_NOT_RUNNING))) 670e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(cpu)); 671e22bee78STejun Heo } 672e22bee78STejun Heo 673e22bee78STejun Heo /** 674e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 675e22bee78STejun Heo * @task: task going to sleep 676e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 677e22bee78STejun Heo * 678e22bee78STejun Heo * This function is called during schedule() when a busy worker is 679e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 680e22bee78STejun Heo * returning pointer to its task. 681e22bee78STejun Heo * 682e22bee78STejun Heo * CONTEXT: 683e22bee78STejun Heo * spin_lock_irq(rq->lock) 684e22bee78STejun Heo * 685e22bee78STejun Heo * RETURNS: 686e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 687e22bee78STejun Heo */ 688e22bee78STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, 689e22bee78STejun Heo unsigned int cpu) 690e22bee78STejun Heo { 691e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 692e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 693e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(cpu); 694e22bee78STejun Heo 695e22bee78STejun Heo if (unlikely(worker->flags & WORKER_NOT_RUNNING)) 696e22bee78STejun Heo return NULL; 697e22bee78STejun Heo 698e22bee78STejun Heo /* this can only happen on the local cpu */ 699e22bee78STejun Heo BUG_ON(cpu != raw_smp_processor_id()); 700e22bee78STejun Heo 701e22bee78STejun Heo /* 702e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 703e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 704e22bee78STejun Heo * Please read comment there. 705e22bee78STejun Heo * 706e22bee78STejun Heo * NOT_RUNNING is clear. This means that trustee is not in 707e22bee78STejun Heo * charge and we're running on the local cpu w/ rq lock held 708e22bee78STejun Heo * and preemption disabled, which in turn means that none else 709e22bee78STejun Heo * could be manipulating idle_list, so dereferencing idle_list 710e22bee78STejun Heo * without gcwq lock is safe. 711e22bee78STejun Heo */ 712e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) 713e22bee78STejun Heo to_wakeup = first_worker(gcwq); 714e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 715e22bee78STejun Heo } 716e22bee78STejun Heo 717e22bee78STejun Heo /** 718e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 719cb444766STejun Heo * @worker: self 720d302f017STejun Heo * @flags: flags to set 721d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 722d302f017STejun Heo * 723e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 724e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 725e22bee78STejun Heo * woken up. 726d302f017STejun Heo * 727cb444766STejun Heo * CONTEXT: 728cb444766STejun Heo * spin_lock_irq(gcwq->lock) 729d302f017STejun Heo */ 730d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 731d302f017STejun Heo bool wakeup) 732d302f017STejun Heo { 733e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 734e22bee78STejun Heo 735cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 736cb444766STejun Heo 737e22bee78STejun Heo /* 738e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 739e22bee78STejun Heo * wake up an idle worker as necessary if requested by 740e22bee78STejun Heo * @wakeup. 741e22bee78STejun Heo */ 742e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 743e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 744e22bee78STejun Heo atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 745e22bee78STejun Heo 746e22bee78STejun Heo if (wakeup) { 747e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && 748e22bee78STejun Heo !list_empty(&gcwq->worklist)) 749e22bee78STejun Heo wake_up_worker(gcwq); 750e22bee78STejun Heo } else 751e22bee78STejun Heo atomic_dec(nr_running); 752e22bee78STejun Heo } 753e22bee78STejun Heo 754d302f017STejun Heo worker->flags |= flags; 755d302f017STejun Heo } 756d302f017STejun Heo 757d302f017STejun Heo /** 758e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 759cb444766STejun Heo * @worker: self 760d302f017STejun Heo * @flags: flags to clear 761d302f017STejun Heo * 762e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 763d302f017STejun Heo * 764cb444766STejun Heo * CONTEXT: 765cb444766STejun Heo * spin_lock_irq(gcwq->lock) 766d302f017STejun Heo */ 767d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 768d302f017STejun Heo { 769e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 770e22bee78STejun Heo unsigned int oflags = worker->flags; 771e22bee78STejun Heo 772cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 773cb444766STejun Heo 774d302f017STejun Heo worker->flags &= ~flags; 775e22bee78STejun Heo 776e22bee78STejun Heo /* if transitioning out of NOT_RUNNING, increment nr_running */ 777e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 778e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 779e22bee78STejun Heo atomic_inc(get_gcwq_nr_running(gcwq->cpu)); 780d302f017STejun Heo } 781d302f017STejun Heo 782d302f017STejun Heo /** 783c8e55f36STejun Heo * busy_worker_head - return the busy hash head for a work 784c8e55f36STejun Heo * @gcwq: gcwq of interest 785c8e55f36STejun Heo * @work: work to be hashed 786c8e55f36STejun Heo * 787c8e55f36STejun Heo * Return hash head of @gcwq for @work. 788c8e55f36STejun Heo * 789c8e55f36STejun Heo * CONTEXT: 790c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 791c8e55f36STejun Heo * 792c8e55f36STejun Heo * RETURNS: 793c8e55f36STejun Heo * Pointer to the hash head. 794c8e55f36STejun Heo */ 795c8e55f36STejun Heo static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, 796c8e55f36STejun Heo struct work_struct *work) 797c8e55f36STejun Heo { 798c8e55f36STejun Heo const int base_shift = ilog2(sizeof(struct work_struct)); 799c8e55f36STejun Heo unsigned long v = (unsigned long)work; 800c8e55f36STejun Heo 801c8e55f36STejun Heo /* simple shift and fold hash, do we need something better? */ 802c8e55f36STejun Heo v >>= base_shift; 803c8e55f36STejun Heo v += v >> BUSY_WORKER_HASH_ORDER; 804c8e55f36STejun Heo v &= BUSY_WORKER_HASH_MASK; 805c8e55f36STejun Heo 806c8e55f36STejun Heo return &gcwq->busy_hash[v]; 807c8e55f36STejun Heo } 808c8e55f36STejun Heo 809c8e55f36STejun Heo /** 8108cca0eeaSTejun Heo * __find_worker_executing_work - find worker which is executing a work 8118cca0eeaSTejun Heo * @gcwq: gcwq of interest 8128cca0eeaSTejun Heo * @bwh: hash head as returned by busy_worker_head() 8138cca0eeaSTejun Heo * @work: work to find worker for 8148cca0eeaSTejun Heo * 8158cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. @bwh should be 8168cca0eeaSTejun Heo * the hash head obtained by calling busy_worker_head() with the same 8178cca0eeaSTejun Heo * work. 8188cca0eeaSTejun Heo * 8198cca0eeaSTejun Heo * CONTEXT: 8208cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8218cca0eeaSTejun Heo * 8228cca0eeaSTejun Heo * RETURNS: 8238cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8248cca0eeaSTejun Heo * otherwise. 8258cca0eeaSTejun Heo */ 8268cca0eeaSTejun Heo static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, 8278cca0eeaSTejun Heo struct hlist_head *bwh, 8288cca0eeaSTejun Heo struct work_struct *work) 8298cca0eeaSTejun Heo { 8308cca0eeaSTejun Heo struct worker *worker; 8318cca0eeaSTejun Heo struct hlist_node *tmp; 8328cca0eeaSTejun Heo 8338cca0eeaSTejun Heo hlist_for_each_entry(worker, tmp, bwh, hentry) 8348cca0eeaSTejun Heo if (worker->current_work == work) 8358cca0eeaSTejun Heo return worker; 8368cca0eeaSTejun Heo return NULL; 8378cca0eeaSTejun Heo } 8388cca0eeaSTejun Heo 8398cca0eeaSTejun Heo /** 8408cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 8418cca0eeaSTejun Heo * @gcwq: gcwq of interest 8428cca0eeaSTejun Heo * @work: work to find worker for 8438cca0eeaSTejun Heo * 8448cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. This function is 8458cca0eeaSTejun Heo * identical to __find_worker_executing_work() except that this 8468cca0eeaSTejun Heo * function calculates @bwh itself. 8478cca0eeaSTejun Heo * 8488cca0eeaSTejun Heo * CONTEXT: 8498cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8508cca0eeaSTejun Heo * 8518cca0eeaSTejun Heo * RETURNS: 8528cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 8538cca0eeaSTejun Heo * otherwise. 8548cca0eeaSTejun Heo */ 8558cca0eeaSTejun Heo static struct worker *find_worker_executing_work(struct global_cwq *gcwq, 8568cca0eeaSTejun Heo struct work_struct *work) 8578cca0eeaSTejun Heo { 8588cca0eeaSTejun Heo return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), 8598cca0eeaSTejun Heo work); 8608cca0eeaSTejun Heo } 8618cca0eeaSTejun Heo 8628cca0eeaSTejun Heo /** 863649027d7STejun Heo * gcwq_determine_ins_pos - find insertion position 864649027d7STejun Heo * @gcwq: gcwq of interest 865649027d7STejun Heo * @cwq: cwq a work is being queued for 866649027d7STejun Heo * 867649027d7STejun Heo * A work for @cwq is about to be queued on @gcwq, determine insertion 868649027d7STejun Heo * position for the work. If @cwq is for HIGHPRI wq, the work is 869649027d7STejun Heo * queued at the head of the queue but in FIFO order with respect to 870649027d7STejun Heo * other HIGHPRI works; otherwise, at the end of the queue. This 871649027d7STejun Heo * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that 872649027d7STejun Heo * there are HIGHPRI works pending. 873649027d7STejun Heo * 874649027d7STejun Heo * CONTEXT: 875649027d7STejun Heo * spin_lock_irq(gcwq->lock). 876649027d7STejun Heo * 877649027d7STejun Heo * RETURNS: 878649027d7STejun Heo * Pointer to inserstion position. 879649027d7STejun Heo */ 880649027d7STejun Heo static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, 8811da177e4SLinus Torvalds struct cpu_workqueue_struct *cwq) 8821da177e4SLinus Torvalds { 883649027d7STejun Heo struct work_struct *twork; 8841da177e4SLinus Torvalds 885649027d7STejun Heo if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) 886649027d7STejun Heo return &gcwq->worklist; 8871da177e4SLinus Torvalds 888649027d7STejun Heo list_for_each_entry(twork, &gcwq->worklist, entry) { 889649027d7STejun Heo struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); 890649027d7STejun Heo 891649027d7STejun Heo if (!(tcwq->wq->flags & WQ_HIGHPRI)) 892649027d7STejun Heo break; 8931da177e4SLinus Torvalds } 8941da177e4SLinus Torvalds 895649027d7STejun Heo gcwq->flags |= GCWQ_HIGHPRI_PENDING; 896649027d7STejun Heo return &twork->entry; 897649027d7STejun Heo } 898649027d7STejun Heo 899649027d7STejun Heo /** 9007e11629dSTejun Heo * insert_work - insert a work into gcwq 9014690c4abSTejun Heo * @cwq: cwq @work belongs to 9024690c4abSTejun Heo * @work: work to insert 9034690c4abSTejun Heo * @head: insertion point 9044690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 9054690c4abSTejun Heo * 9067e11629dSTejun Heo * Insert @work which belongs to @cwq into @gcwq after @head. 9077e11629dSTejun Heo * @extra_flags is or'd to work_struct flags. 9084690c4abSTejun Heo * 9094690c4abSTejun Heo * CONTEXT: 9108b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 9111da177e4SLinus Torvalds */ 912b89deed3SOleg Nesterov static void insert_work(struct cpu_workqueue_struct *cwq, 9134690c4abSTejun Heo struct work_struct *work, struct list_head *head, 9144690c4abSTejun Heo unsigned int extra_flags) 915b89deed3SOleg Nesterov { 916e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 917e1d8aa9fSFrederic Weisbecker 9184690c4abSTejun Heo /* we own @work, set data and link */ 9197a22ad75STejun Heo set_work_cwq(work, cwq, extra_flags); 9204690c4abSTejun Heo 9216e84d644SOleg Nesterov /* 9226e84d644SOleg Nesterov * Ensure that we get the right work->data if we see the 9236e84d644SOleg Nesterov * result of list_add() below, see try_to_grab_pending(). 9246e84d644SOleg Nesterov */ 9256e84d644SOleg Nesterov smp_wmb(); 9264690c4abSTejun Heo 9271a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 928e22bee78STejun Heo 929e22bee78STejun Heo /* 930e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 931e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 932e22bee78STejun Heo * lying around lazily while there are works to be processed. 933e22bee78STejun Heo */ 934e22bee78STejun Heo smp_mb(); 935e22bee78STejun Heo 936649027d7STejun Heo if (__need_more_worker(gcwq)) 937e22bee78STejun Heo wake_up_worker(gcwq); 938b89deed3SOleg Nesterov } 939b89deed3SOleg Nesterov 9404690c4abSTejun Heo static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 9411da177e4SLinus Torvalds struct work_struct *work) 9421da177e4SLinus Torvalds { 943502ca9d8STejun Heo struct global_cwq *gcwq; 944502ca9d8STejun Heo struct cpu_workqueue_struct *cwq; 9451e19ffc6STejun Heo struct list_head *worklist; 9461da177e4SLinus Torvalds unsigned long flags; 9471da177e4SLinus Torvalds 948dc186ad7SThomas Gleixner debug_work_activate(work); 9491e19ffc6STejun Heo 950c7fc77f7STejun Heo /* determine gcwq to use */ 951c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 952c7fc77f7STejun Heo struct global_cwq *last_gcwq; 953c7fc77f7STejun Heo 954f3421797STejun Heo if (unlikely(cpu == WORK_CPU_UNBOUND)) 955f3421797STejun Heo cpu = raw_smp_processor_id(); 956f3421797STejun Heo 95718aa9effSTejun Heo /* 95818aa9effSTejun Heo * It's multi cpu. If @wq is non-reentrant and @work 95918aa9effSTejun Heo * was previously on a different cpu, it might still 96018aa9effSTejun Heo * be running there, in which case the work needs to 96118aa9effSTejun Heo * be queued on that cpu to guarantee non-reentrance. 96218aa9effSTejun Heo */ 963502ca9d8STejun Heo gcwq = get_gcwq(cpu); 96418aa9effSTejun Heo if (wq->flags & WQ_NON_REENTRANT && 96518aa9effSTejun Heo (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { 96618aa9effSTejun Heo struct worker *worker; 96718aa9effSTejun Heo 96818aa9effSTejun Heo spin_lock_irqsave(&last_gcwq->lock, flags); 96918aa9effSTejun Heo 97018aa9effSTejun Heo worker = find_worker_executing_work(last_gcwq, work); 97118aa9effSTejun Heo 97218aa9effSTejun Heo if (worker && worker->current_cwq->wq == wq) 97318aa9effSTejun Heo gcwq = last_gcwq; 97418aa9effSTejun Heo else { 97518aa9effSTejun Heo /* meh... not running there, queue here */ 97618aa9effSTejun Heo spin_unlock_irqrestore(&last_gcwq->lock, flags); 97718aa9effSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 97818aa9effSTejun Heo } 97918aa9effSTejun Heo } else 9808b03ae3cSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 981f3421797STejun Heo } else { 982f3421797STejun Heo gcwq = get_gcwq(WORK_CPU_UNBOUND); 983f3421797STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 984502ca9d8STejun Heo } 985502ca9d8STejun Heo 986502ca9d8STejun Heo /* gcwq determined, get cwq and queue */ 987502ca9d8STejun Heo cwq = get_cwq(gcwq->cpu, wq); 988502ca9d8STejun Heo 9894690c4abSTejun Heo BUG_ON(!list_empty(&work->entry)); 9901e19ffc6STejun Heo 99173f53c4aSTejun Heo cwq->nr_in_flight[cwq->work_color]++; 9921e19ffc6STejun Heo 9931e19ffc6STejun Heo if (likely(cwq->nr_active < cwq->max_active)) { 9941e19ffc6STejun Heo cwq->nr_active++; 995649027d7STejun Heo worklist = gcwq_determine_ins_pos(gcwq, cwq); 9961e19ffc6STejun Heo } else 9971e19ffc6STejun Heo worklist = &cwq->delayed_works; 9981e19ffc6STejun Heo 9991e19ffc6STejun Heo insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color)); 10001e19ffc6STejun Heo 10018b03ae3cSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 10021da177e4SLinus Torvalds } 10031da177e4SLinus Torvalds 10040fcb78c2SRolf Eike Beer /** 10050fcb78c2SRolf Eike Beer * queue_work - queue work on a workqueue 10060fcb78c2SRolf Eike Beer * @wq: workqueue to use 10070fcb78c2SRolf Eike Beer * @work: work to queue 10080fcb78c2SRolf Eike Beer * 1009057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10101da177e4SLinus Torvalds * 101100dfcaf7SOleg Nesterov * We queue the work to the CPU on which it was submitted, but if the CPU dies 101200dfcaf7SOleg Nesterov * it can be processed by another CPU. 10131da177e4SLinus Torvalds */ 10147ad5b3a5SHarvey Harrison int queue_work(struct workqueue_struct *wq, struct work_struct *work) 10151da177e4SLinus Torvalds { 1016ef1ca236SOleg Nesterov int ret; 10171da177e4SLinus Torvalds 1018ef1ca236SOleg Nesterov ret = queue_work_on(get_cpu(), wq, work); 1019a848e3b6SOleg Nesterov put_cpu(); 1020ef1ca236SOleg Nesterov 10211da177e4SLinus Torvalds return ret; 10221da177e4SLinus Torvalds } 1023ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_work); 10241da177e4SLinus Torvalds 1025c1a220e7SZhang Rui /** 1026c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1027c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1028c1a220e7SZhang Rui * @wq: workqueue to use 1029c1a220e7SZhang Rui * @work: work to queue 1030c1a220e7SZhang Rui * 1031c1a220e7SZhang Rui * Returns 0 if @work was already on a queue, non-zero otherwise. 1032c1a220e7SZhang Rui * 1033c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1034c1a220e7SZhang Rui * can't go away. 1035c1a220e7SZhang Rui */ 1036c1a220e7SZhang Rui int 1037c1a220e7SZhang Rui queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) 1038c1a220e7SZhang Rui { 1039c1a220e7SZhang Rui int ret = 0; 1040c1a220e7SZhang Rui 104122df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 10424690c4abSTejun Heo __queue_work(cpu, wq, work); 1043c1a220e7SZhang Rui ret = 1; 1044c1a220e7SZhang Rui } 1045c1a220e7SZhang Rui return ret; 1046c1a220e7SZhang Rui } 1047c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1048c1a220e7SZhang Rui 10496d141c3fSLi Zefan static void delayed_work_timer_fn(unsigned long __data) 10501da177e4SLinus Torvalds { 105152bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 10527a22ad75STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); 10531da177e4SLinus Torvalds 10544690c4abSTejun Heo __queue_work(smp_processor_id(), cwq->wq, &dwork->work); 10551da177e4SLinus Torvalds } 10561da177e4SLinus Torvalds 10570fcb78c2SRolf Eike Beer /** 10580fcb78c2SRolf Eike Beer * queue_delayed_work - queue work on a workqueue after delay 10590fcb78c2SRolf Eike Beer * @wq: workqueue to use 1060af9997e4SRandy Dunlap * @dwork: delayable work to queue 10610fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10620fcb78c2SRolf Eike Beer * 1063057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10640fcb78c2SRolf Eike Beer */ 10657ad5b3a5SHarvey Harrison int queue_delayed_work(struct workqueue_struct *wq, 106652bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 10671da177e4SLinus Torvalds { 106852bad64dSDavid Howells if (delay == 0) 106963bc0362SOleg Nesterov return queue_work(wq, &dwork->work); 10701da177e4SLinus Torvalds 107163bc0362SOleg Nesterov return queue_delayed_work_on(-1, wq, dwork, delay); 10721da177e4SLinus Torvalds } 1073ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work); 10741da177e4SLinus Torvalds 10750fcb78c2SRolf Eike Beer /** 10760fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 10770fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 10780fcb78c2SRolf Eike Beer * @wq: workqueue to use 1079af9997e4SRandy Dunlap * @dwork: work to queue 10800fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 10810fcb78c2SRolf Eike Beer * 1082057647fcSAlan Stern * Returns 0 if @work was already on a queue, non-zero otherwise. 10830fcb78c2SRolf Eike Beer */ 10847a6bc1cdSVenkatesh Pallipadi int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 108552bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 10867a6bc1cdSVenkatesh Pallipadi { 10877a6bc1cdSVenkatesh Pallipadi int ret = 0; 108852bad64dSDavid Howells struct timer_list *timer = &dwork->timer; 108952bad64dSDavid Howells struct work_struct *work = &dwork->work; 10907a6bc1cdSVenkatesh Pallipadi 109122df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 1092c7fc77f7STejun Heo unsigned int lcpu; 10937a22ad75STejun Heo 10947a6bc1cdSVenkatesh Pallipadi BUG_ON(timer_pending(timer)); 10957a6bc1cdSVenkatesh Pallipadi BUG_ON(!list_empty(&work->entry)); 10967a6bc1cdSVenkatesh Pallipadi 10978a3e77ccSAndrew Liu timer_stats_timer_set_start_info(&dwork->timer); 10988a3e77ccSAndrew Liu 10997a22ad75STejun Heo /* 11007a22ad75STejun Heo * This stores cwq for the moment, for the timer_fn. 11017a22ad75STejun Heo * Note that the work's gcwq is preserved to allow 11027a22ad75STejun Heo * reentrance detection for delayed works. 11037a22ad75STejun Heo */ 1104c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1105c7fc77f7STejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 1106c7fc77f7STejun Heo 1107c7fc77f7STejun Heo if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) 1108c7fc77f7STejun Heo lcpu = gcwq->cpu; 1109c7fc77f7STejun Heo else 1110c7fc77f7STejun Heo lcpu = raw_smp_processor_id(); 1111c7fc77f7STejun Heo } else 1112c7fc77f7STejun Heo lcpu = WORK_CPU_UNBOUND; 1113c7fc77f7STejun Heo 11147a22ad75STejun Heo set_work_cwq(work, get_cwq(lcpu, wq), 0); 1115c7fc77f7STejun Heo 11167a6bc1cdSVenkatesh Pallipadi timer->expires = jiffies + delay; 111752bad64dSDavid Howells timer->data = (unsigned long)dwork; 11187a6bc1cdSVenkatesh Pallipadi timer->function = delayed_work_timer_fn; 111963bc0362SOleg Nesterov 112063bc0362SOleg Nesterov if (unlikely(cpu >= 0)) 11217a6bc1cdSVenkatesh Pallipadi add_timer_on(timer, cpu); 112263bc0362SOleg Nesterov else 112363bc0362SOleg Nesterov add_timer(timer); 11247a6bc1cdSVenkatesh Pallipadi ret = 1; 11257a6bc1cdSVenkatesh Pallipadi } 11267a6bc1cdSVenkatesh Pallipadi return ret; 11277a6bc1cdSVenkatesh Pallipadi } 1128ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 11291da177e4SLinus Torvalds 1130c8e55f36STejun Heo /** 1131c8e55f36STejun Heo * worker_enter_idle - enter idle state 1132c8e55f36STejun Heo * @worker: worker which is entering idle state 1133c8e55f36STejun Heo * 1134c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1135c8e55f36STejun Heo * necessary. 1136c8e55f36STejun Heo * 1137c8e55f36STejun Heo * LOCKING: 1138c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1139c8e55f36STejun Heo */ 1140c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 11411da177e4SLinus Torvalds { 1142c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1143c8e55f36STejun Heo 1144c8e55f36STejun Heo BUG_ON(worker->flags & WORKER_IDLE); 1145c8e55f36STejun Heo BUG_ON(!list_empty(&worker->entry) && 1146c8e55f36STejun Heo (worker->hentry.next || worker->hentry.pprev)); 1147c8e55f36STejun Heo 1148cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1149cb444766STejun Heo worker->flags |= WORKER_IDLE; 1150c8e55f36STejun Heo gcwq->nr_idle++; 1151e22bee78STejun Heo worker->last_active = jiffies; 1152c8e55f36STejun Heo 1153c8e55f36STejun Heo /* idle_list is LIFO */ 1154c8e55f36STejun Heo list_add(&worker->entry, &gcwq->idle_list); 1155db7bccf4STejun Heo 1156e22bee78STejun Heo if (likely(!(worker->flags & WORKER_ROGUE))) { 1157e22bee78STejun Heo if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) 1158e22bee78STejun Heo mod_timer(&gcwq->idle_timer, 1159e22bee78STejun Heo jiffies + IDLE_WORKER_TIMEOUT); 1160e22bee78STejun Heo } else 1161db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 1162cb444766STejun Heo 1163cb444766STejun Heo /* sanity check nr_running */ 1164cb444766STejun Heo WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && 1165cb444766STejun Heo atomic_read(get_gcwq_nr_running(gcwq->cpu))); 1166c8e55f36STejun Heo } 1167c8e55f36STejun Heo 1168c8e55f36STejun Heo /** 1169c8e55f36STejun Heo * worker_leave_idle - leave idle state 1170c8e55f36STejun Heo * @worker: worker which is leaving idle state 1171c8e55f36STejun Heo * 1172c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1173c8e55f36STejun Heo * 1174c8e55f36STejun Heo * LOCKING: 1175c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1176c8e55f36STejun Heo */ 1177c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1178c8e55f36STejun Heo { 1179c8e55f36STejun Heo struct global_cwq *gcwq = worker->gcwq; 1180c8e55f36STejun Heo 1181c8e55f36STejun Heo BUG_ON(!(worker->flags & WORKER_IDLE)); 1182d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1183c8e55f36STejun Heo gcwq->nr_idle--; 1184c8e55f36STejun Heo list_del_init(&worker->entry); 1185c8e55f36STejun Heo } 1186c8e55f36STejun Heo 1187e22bee78STejun Heo /** 1188e22bee78STejun Heo * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq 1189e22bee78STejun Heo * @worker: self 1190e22bee78STejun Heo * 1191e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1192e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1193e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1194e22bee78STejun Heo * guaranteed to execute on the cpu. 1195e22bee78STejun Heo * 1196e22bee78STejun Heo * This function is to be used by rogue workers and rescuers to bind 1197e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1198e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1199e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1200e22bee78STejun Heo * verbatim as it's best effort and blocking and gcwq may be 1201e22bee78STejun Heo * [dis]associated in the meantime. 1202e22bee78STejun Heo * 1203e22bee78STejun Heo * This function tries set_cpus_allowed() and locks gcwq and verifies 1204e22bee78STejun Heo * the binding against GCWQ_DISASSOCIATED which is set during 1205e22bee78STejun Heo * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters 1206e22bee78STejun Heo * idle state or fetches works without dropping lock, it can guarantee 1207e22bee78STejun Heo * the scheduling requirement described in the first paragraph. 1208e22bee78STejun Heo * 1209e22bee78STejun Heo * CONTEXT: 1210e22bee78STejun Heo * Might sleep. Called without any lock but returns with gcwq->lock 1211e22bee78STejun Heo * held. 1212e22bee78STejun Heo * 1213e22bee78STejun Heo * RETURNS: 1214e22bee78STejun Heo * %true if the associated gcwq is online (@worker is successfully 1215e22bee78STejun Heo * bound), %false if offline. 1216e22bee78STejun Heo */ 1217e22bee78STejun Heo static bool worker_maybe_bind_and_lock(struct worker *worker) 1218e22bee78STejun Heo { 1219e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1220e22bee78STejun Heo struct task_struct *task = worker->task; 1221e22bee78STejun Heo 1222e22bee78STejun Heo while (true) { 1223e22bee78STejun Heo /* 1224e22bee78STejun Heo * The following call may fail, succeed or succeed 1225e22bee78STejun Heo * without actually migrating the task to the cpu if 1226e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 1227e22bee78STejun Heo * against GCWQ_DISASSOCIATED. 1228e22bee78STejun Heo */ 1229f3421797STejun Heo if (!(gcwq->flags & GCWQ_DISASSOCIATED)) 1230e22bee78STejun Heo set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); 1231e22bee78STejun Heo 1232e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1233e22bee78STejun Heo if (gcwq->flags & GCWQ_DISASSOCIATED) 1234e22bee78STejun Heo return false; 1235e22bee78STejun Heo if (task_cpu(task) == gcwq->cpu && 1236e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1237e22bee78STejun Heo get_cpu_mask(gcwq->cpu))) 1238e22bee78STejun Heo return true; 1239e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1240e22bee78STejun Heo 1241e22bee78STejun Heo /* CPU has come up inbetween, retry migration */ 1242e22bee78STejun Heo cpu_relax(); 1243e22bee78STejun Heo } 1244e22bee78STejun Heo } 1245e22bee78STejun Heo 1246e22bee78STejun Heo /* 1247e22bee78STejun Heo * Function for worker->rebind_work used to rebind rogue busy workers 1248e22bee78STejun Heo * to the associated cpu which is coming back online. This is 1249e22bee78STejun Heo * scheduled by cpu up but can race with other cpu hotplug operations 1250e22bee78STejun Heo * and may be executed twice without intervening cpu down. 1251e22bee78STejun Heo */ 1252e22bee78STejun Heo static void worker_rebind_fn(struct work_struct *work) 1253e22bee78STejun Heo { 1254e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1255e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1256e22bee78STejun Heo 1257e22bee78STejun Heo if (worker_maybe_bind_and_lock(worker)) 1258e22bee78STejun Heo worker_clr_flags(worker, WORKER_REBIND); 1259e22bee78STejun Heo 1260e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1261e22bee78STejun Heo } 1262e22bee78STejun Heo 1263c34056a3STejun Heo static struct worker *alloc_worker(void) 1264c34056a3STejun Heo { 1265c34056a3STejun Heo struct worker *worker; 1266c34056a3STejun Heo 1267c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1268c8e55f36STejun Heo if (worker) { 1269c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1270affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1271e22bee78STejun Heo INIT_WORK(&worker->rebind_work, worker_rebind_fn); 1272e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1273e22bee78STejun Heo worker->flags = WORKER_PREP; 1274c8e55f36STejun Heo } 1275c34056a3STejun Heo return worker; 1276c34056a3STejun Heo } 1277c34056a3STejun Heo 1278c34056a3STejun Heo /** 1279c34056a3STejun Heo * create_worker - create a new workqueue worker 12807e11629dSTejun Heo * @gcwq: gcwq the new worker will belong to 1281c34056a3STejun Heo * @bind: whether to set affinity to @cpu or not 1282c34056a3STejun Heo * 12837e11629dSTejun Heo * Create a new worker which is bound to @gcwq. The returned worker 1284c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1285c34056a3STejun Heo * destroy_worker(). 1286c34056a3STejun Heo * 1287c34056a3STejun Heo * CONTEXT: 1288c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1289c34056a3STejun Heo * 1290c34056a3STejun Heo * RETURNS: 1291c34056a3STejun Heo * Pointer to the newly created worker. 1292c34056a3STejun Heo */ 12937e11629dSTejun Heo static struct worker *create_worker(struct global_cwq *gcwq, bool bind) 1294c34056a3STejun Heo { 1295f3421797STejun Heo bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; 1296c34056a3STejun Heo struct worker *worker = NULL; 1297f3421797STejun Heo int id = -1; 1298c34056a3STejun Heo 12998b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13008b03ae3cSTejun Heo while (ida_get_new(&gcwq->worker_ida, &id)) { 13018b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 13028b03ae3cSTejun Heo if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) 1303c34056a3STejun Heo goto fail; 13048b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1305c34056a3STejun Heo } 13068b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1307c34056a3STejun Heo 1308c34056a3STejun Heo worker = alloc_worker(); 1309c34056a3STejun Heo if (!worker) 1310c34056a3STejun Heo goto fail; 1311c34056a3STejun Heo 13128b03ae3cSTejun Heo worker->gcwq = gcwq; 1313c34056a3STejun Heo worker->id = id; 1314c34056a3STejun Heo 1315f3421797STejun Heo if (!on_unbound_cpu) 1316f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1317f3421797STejun Heo "kworker/%u:%d", gcwq->cpu, id); 1318f3421797STejun Heo else 1319f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 1320f3421797STejun Heo "kworker/u:%d", id); 1321c34056a3STejun Heo if (IS_ERR(worker->task)) 1322c34056a3STejun Heo goto fail; 1323c34056a3STejun Heo 1324db7bccf4STejun Heo /* 1325db7bccf4STejun Heo * A rogue worker will become a regular one if CPU comes 1326db7bccf4STejun Heo * online later on. Make sure every worker has 1327db7bccf4STejun Heo * PF_THREAD_BOUND set. 1328db7bccf4STejun Heo */ 1329f3421797STejun Heo if (bind && !on_unbound_cpu) 13308b03ae3cSTejun Heo kthread_bind(worker->task, gcwq->cpu); 1331f3421797STejun Heo else { 1332db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1333f3421797STejun Heo if (on_unbound_cpu) 1334f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1335f3421797STejun Heo } 1336c34056a3STejun Heo 1337c34056a3STejun Heo return worker; 1338c34056a3STejun Heo fail: 1339c34056a3STejun Heo if (id >= 0) { 13408b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13418b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 13428b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1343c34056a3STejun Heo } 1344c34056a3STejun Heo kfree(worker); 1345c34056a3STejun Heo return NULL; 1346c34056a3STejun Heo } 1347c34056a3STejun Heo 1348c34056a3STejun Heo /** 1349c34056a3STejun Heo * start_worker - start a newly created worker 1350c34056a3STejun Heo * @worker: worker to start 1351c34056a3STejun Heo * 1352c8e55f36STejun Heo * Make the gcwq aware of @worker and start it. 1353c34056a3STejun Heo * 1354c34056a3STejun Heo * CONTEXT: 13558b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1356c34056a3STejun Heo */ 1357c34056a3STejun Heo static void start_worker(struct worker *worker) 1358c34056a3STejun Heo { 1359cb444766STejun Heo worker->flags |= WORKER_STARTED; 1360c8e55f36STejun Heo worker->gcwq->nr_workers++; 1361c8e55f36STejun Heo worker_enter_idle(worker); 1362c34056a3STejun Heo wake_up_process(worker->task); 1363c34056a3STejun Heo } 1364c34056a3STejun Heo 1365c34056a3STejun Heo /** 1366c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1367c34056a3STejun Heo * @worker: worker to be destroyed 1368c34056a3STejun Heo * 1369c8e55f36STejun Heo * Destroy @worker and adjust @gcwq stats accordingly. 1370c8e55f36STejun Heo * 1371c8e55f36STejun Heo * CONTEXT: 1372c8e55f36STejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1373c34056a3STejun Heo */ 1374c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1375c34056a3STejun Heo { 13768b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 1377c34056a3STejun Heo int id = worker->id; 1378c34056a3STejun Heo 1379c34056a3STejun Heo /* sanity check frenzy */ 1380c34056a3STejun Heo BUG_ON(worker->current_work); 1381affee4b2STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1382c34056a3STejun Heo 1383c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1384c8e55f36STejun Heo gcwq->nr_workers--; 1385c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1386c8e55f36STejun Heo gcwq->nr_idle--; 1387c8e55f36STejun Heo 1388c8e55f36STejun Heo list_del_init(&worker->entry); 1389cb444766STejun Heo worker->flags |= WORKER_DIE; 1390c8e55f36STejun Heo 1391c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1392c8e55f36STejun Heo 1393c34056a3STejun Heo kthread_stop(worker->task); 1394c34056a3STejun Heo kfree(worker); 1395c34056a3STejun Heo 13968b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 13978b03ae3cSTejun Heo ida_remove(&gcwq->worker_ida, id); 1398c34056a3STejun Heo } 1399c34056a3STejun Heo 1400e22bee78STejun Heo static void idle_worker_timeout(unsigned long __gcwq) 1401e22bee78STejun Heo { 1402e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1403e22bee78STejun Heo 1404e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1405e22bee78STejun Heo 1406e22bee78STejun Heo if (too_many_workers(gcwq)) { 1407e22bee78STejun Heo struct worker *worker; 1408e22bee78STejun Heo unsigned long expires; 1409e22bee78STejun Heo 1410e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 1411e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1412e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1413e22bee78STejun Heo 1414e22bee78STejun Heo if (time_before(jiffies, expires)) 1415e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1416e22bee78STejun Heo else { 1417e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 1418e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 1419e22bee78STejun Heo wake_up_worker(gcwq); 1420e22bee78STejun Heo } 1421e22bee78STejun Heo } 1422e22bee78STejun Heo 1423e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1424e22bee78STejun Heo } 1425e22bee78STejun Heo 1426e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1427e22bee78STejun Heo { 1428e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1429e22bee78STejun Heo struct workqueue_struct *wq = cwq->wq; 1430f3421797STejun Heo unsigned int cpu; 1431e22bee78STejun Heo 1432e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1433e22bee78STejun Heo return false; 1434e22bee78STejun Heo 1435e22bee78STejun Heo /* mayday mayday mayday */ 1436f3421797STejun Heo cpu = cwq->gcwq->cpu; 1437f3421797STejun Heo /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1438f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 1439f3421797STejun Heo cpu = 0; 1440f2e005aaSTejun Heo if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) 1441e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1442e22bee78STejun Heo return true; 1443e22bee78STejun Heo } 1444e22bee78STejun Heo 1445e22bee78STejun Heo static void gcwq_mayday_timeout(unsigned long __gcwq) 1446e22bee78STejun Heo { 1447e22bee78STejun Heo struct global_cwq *gcwq = (void *)__gcwq; 1448e22bee78STejun Heo struct work_struct *work; 1449e22bee78STejun Heo 1450e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1451e22bee78STejun Heo 1452e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 1453e22bee78STejun Heo /* 1454e22bee78STejun Heo * We've been trying to create a new worker but 1455e22bee78STejun Heo * haven't been successful. We might be hitting an 1456e22bee78STejun Heo * allocation deadlock. Send distress signals to 1457e22bee78STejun Heo * rescuers. 1458e22bee78STejun Heo */ 1459e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) 1460e22bee78STejun Heo send_mayday(work); 1461e22bee78STejun Heo } 1462e22bee78STejun Heo 1463e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1464e22bee78STejun Heo 1465e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); 1466e22bee78STejun Heo } 1467e22bee78STejun Heo 1468e22bee78STejun Heo /** 1469e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 1470e22bee78STejun Heo * @gcwq: gcwq to create a new worker for 1471e22bee78STejun Heo * 1472e22bee78STejun Heo * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to 1473e22bee78STejun Heo * have at least one idle worker on return from this function. If 1474e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 1475e22bee78STejun Heo * sent to all rescuers with works scheduled on @gcwq to resolve 1476e22bee78STejun Heo * possible allocation deadlock. 1477e22bee78STejun Heo * 1478e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1479e22bee78STejun Heo * may_start_working() true. 1480e22bee78STejun Heo * 1481e22bee78STejun Heo * LOCKING: 1482e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1483e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1484e22bee78STejun Heo * manager. 1485e22bee78STejun Heo * 1486e22bee78STejun Heo * RETURNS: 1487e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1488e22bee78STejun Heo * otherwise. 1489e22bee78STejun Heo */ 1490e22bee78STejun Heo static bool maybe_create_worker(struct global_cwq *gcwq) 1491e22bee78STejun Heo { 1492e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1493e22bee78STejun Heo return false; 1494e22bee78STejun Heo restart: 14959f9c2364STejun Heo spin_unlock_irq(&gcwq->lock); 14969f9c2364STejun Heo 1497e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 1498e22bee78STejun Heo mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1499e22bee78STejun Heo 1500e22bee78STejun Heo while (true) { 1501e22bee78STejun Heo struct worker *worker; 1502e22bee78STejun Heo 1503e22bee78STejun Heo worker = create_worker(gcwq, true); 1504e22bee78STejun Heo if (worker) { 1505e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1506e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1507e22bee78STejun Heo start_worker(worker); 1508e22bee78STejun Heo BUG_ON(need_to_create_worker(gcwq)); 1509e22bee78STejun Heo return true; 1510e22bee78STejun Heo } 1511e22bee78STejun Heo 1512e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1513e22bee78STejun Heo break; 1514e22bee78STejun Heo 1515e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1516e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 15179f9c2364STejun Heo 1518e22bee78STejun Heo if (!need_to_create_worker(gcwq)) 1519e22bee78STejun Heo break; 1520e22bee78STejun Heo } 1521e22bee78STejun Heo 1522e22bee78STejun Heo del_timer_sync(&gcwq->mayday_timer); 1523e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1524e22bee78STejun Heo if (need_to_create_worker(gcwq)) 1525e22bee78STejun Heo goto restart; 1526e22bee78STejun Heo return true; 1527e22bee78STejun Heo } 1528e22bee78STejun Heo 1529e22bee78STejun Heo /** 1530e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 1531e22bee78STejun Heo * @gcwq: gcwq to destroy workers for 1532e22bee78STejun Heo * 1533e22bee78STejun Heo * Destroy @gcwq workers which have been idle for longer than 1534e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1535e22bee78STejun Heo * 1536e22bee78STejun Heo * LOCKING: 1537e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1538e22bee78STejun Heo * multiple times. Called only from manager. 1539e22bee78STejun Heo * 1540e22bee78STejun Heo * RETURNS: 1541e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 1542e22bee78STejun Heo * otherwise. 1543e22bee78STejun Heo */ 1544e22bee78STejun Heo static bool maybe_destroy_workers(struct global_cwq *gcwq) 1545e22bee78STejun Heo { 1546e22bee78STejun Heo bool ret = false; 1547e22bee78STejun Heo 1548e22bee78STejun Heo while (too_many_workers(gcwq)) { 1549e22bee78STejun Heo struct worker *worker; 1550e22bee78STejun Heo unsigned long expires; 1551e22bee78STejun Heo 1552e22bee78STejun Heo worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1553e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1554e22bee78STejun Heo 1555e22bee78STejun Heo if (time_before(jiffies, expires)) { 1556e22bee78STejun Heo mod_timer(&gcwq->idle_timer, expires); 1557e22bee78STejun Heo break; 1558e22bee78STejun Heo } 1559e22bee78STejun Heo 1560e22bee78STejun Heo destroy_worker(worker); 1561e22bee78STejun Heo ret = true; 1562e22bee78STejun Heo } 1563e22bee78STejun Heo 1564e22bee78STejun Heo return ret; 1565e22bee78STejun Heo } 1566e22bee78STejun Heo 1567e22bee78STejun Heo /** 1568e22bee78STejun Heo * manage_workers - manage worker pool 1569e22bee78STejun Heo * @worker: self 1570e22bee78STejun Heo * 1571e22bee78STejun Heo * Assume the manager role and manage gcwq worker pool @worker belongs 1572e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 1573e22bee78STejun Heo * gcwq. The exclusion is handled automatically by this function. 1574e22bee78STejun Heo * 1575e22bee78STejun Heo * The caller can safely start processing works on false return. On 1576e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 1577e22bee78STejun Heo * and may_start_working() is true. 1578e22bee78STejun Heo * 1579e22bee78STejun Heo * CONTEXT: 1580e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1581e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 1582e22bee78STejun Heo * 1583e22bee78STejun Heo * RETURNS: 1584e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true if 1585e22bee78STejun Heo * some action was taken. 1586e22bee78STejun Heo */ 1587e22bee78STejun Heo static bool manage_workers(struct worker *worker) 1588e22bee78STejun Heo { 1589e22bee78STejun Heo struct global_cwq *gcwq = worker->gcwq; 1590e22bee78STejun Heo bool ret = false; 1591e22bee78STejun Heo 1592e22bee78STejun Heo if (gcwq->flags & GCWQ_MANAGING_WORKERS) 1593e22bee78STejun Heo return ret; 1594e22bee78STejun Heo 1595e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGE_WORKERS; 1596e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 1597e22bee78STejun Heo 1598e22bee78STejun Heo /* 1599e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 1600e22bee78STejun Heo * on return. 1601e22bee78STejun Heo */ 1602e22bee78STejun Heo ret |= maybe_destroy_workers(gcwq); 1603e22bee78STejun Heo ret |= maybe_create_worker(gcwq); 1604e22bee78STejun Heo 1605e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 1606e22bee78STejun Heo 1607e22bee78STejun Heo /* 1608e22bee78STejun Heo * The trustee might be waiting to take over the manager 1609e22bee78STejun Heo * position, tell it we're done. 1610e22bee78STejun Heo */ 1611e22bee78STejun Heo if (unlikely(gcwq->trustee)) 1612e22bee78STejun Heo wake_up_all(&gcwq->trustee_wait); 1613e22bee78STejun Heo 1614e22bee78STejun Heo return ret; 1615e22bee78STejun Heo } 1616e22bee78STejun Heo 1617a62428c0STejun Heo /** 1618affee4b2STejun Heo * move_linked_works - move linked works to a list 1619affee4b2STejun Heo * @work: start of series of works to be scheduled 1620affee4b2STejun Heo * @head: target list to append @work to 1621affee4b2STejun Heo * @nextp: out paramter for nested worklist walking 1622affee4b2STejun Heo * 1623affee4b2STejun Heo * Schedule linked works starting from @work to @head. Work series to 1624affee4b2STejun Heo * be scheduled starts at @work and includes any consecutive work with 1625affee4b2STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 1626affee4b2STejun Heo * 1627affee4b2STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 1628affee4b2STejun Heo * the last scheduled work. This allows move_linked_works() to be 1629affee4b2STejun Heo * nested inside outer list_for_each_entry_safe(). 1630affee4b2STejun Heo * 1631affee4b2STejun Heo * CONTEXT: 16328b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1633affee4b2STejun Heo */ 1634affee4b2STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1635affee4b2STejun Heo struct work_struct **nextp) 1636affee4b2STejun Heo { 1637affee4b2STejun Heo struct work_struct *n; 1638affee4b2STejun Heo 1639affee4b2STejun Heo /* 1640affee4b2STejun Heo * Linked worklist will always end before the end of the list, 1641affee4b2STejun Heo * use NULL for list head. 1642affee4b2STejun Heo */ 1643affee4b2STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1644affee4b2STejun Heo list_move_tail(&work->entry, head); 1645affee4b2STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1646affee4b2STejun Heo break; 1647affee4b2STejun Heo } 1648affee4b2STejun Heo 1649affee4b2STejun Heo /* 1650affee4b2STejun Heo * If we're already inside safe list traversal and have moved 1651affee4b2STejun Heo * multiple works to the scheduled queue, the next position 1652affee4b2STejun Heo * needs to be updated. 1653affee4b2STejun Heo */ 1654affee4b2STejun Heo if (nextp) 1655affee4b2STejun Heo *nextp = n; 1656affee4b2STejun Heo } 1657affee4b2STejun Heo 16581e19ffc6STejun Heo static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) 16591e19ffc6STejun Heo { 16601e19ffc6STejun Heo struct work_struct *work = list_first_entry(&cwq->delayed_works, 16611da177e4SLinus Torvalds struct work_struct, entry); 1662649027d7STejun Heo struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); 16631e19ffc6STejun Heo 1664649027d7STejun Heo move_linked_works(work, pos, NULL); 16651e19ffc6STejun Heo cwq->nr_active++; 16661e19ffc6STejun Heo } 16671e19ffc6STejun Heo 1668affee4b2STejun Heo /** 166973f53c4aSTejun Heo * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight 167073f53c4aSTejun Heo * @cwq: cwq of interest 167173f53c4aSTejun Heo * @color: color of work which left the queue 167273f53c4aSTejun Heo * 167373f53c4aSTejun Heo * A work either has completed or is removed from pending queue, 167473f53c4aSTejun Heo * decrement nr_in_flight of its cwq and handle workqueue flushing. 167573f53c4aSTejun Heo * 167673f53c4aSTejun Heo * CONTEXT: 16778b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 167873f53c4aSTejun Heo */ 167973f53c4aSTejun Heo static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) 168073f53c4aSTejun Heo { 168173f53c4aSTejun Heo /* ignore uncolored works */ 168273f53c4aSTejun Heo if (color == WORK_NO_COLOR) 168373f53c4aSTejun Heo return; 168473f53c4aSTejun Heo 168573f53c4aSTejun Heo cwq->nr_in_flight[color]--; 16861e19ffc6STejun Heo cwq->nr_active--; 16871e19ffc6STejun Heo 1688502ca9d8STejun Heo if (!list_empty(&cwq->delayed_works)) { 16891e19ffc6STejun Heo /* one down, submit a delayed one */ 1690502ca9d8STejun Heo if (cwq->nr_active < cwq->max_active) 16911e19ffc6STejun Heo cwq_activate_first_delayed(cwq); 1692502ca9d8STejun Heo } 169373f53c4aSTejun Heo 169473f53c4aSTejun Heo /* is flush in progress and are we at the flushing tip? */ 169573f53c4aSTejun Heo if (likely(cwq->flush_color != color)) 169673f53c4aSTejun Heo return; 169773f53c4aSTejun Heo 169873f53c4aSTejun Heo /* are there still in-flight works? */ 169973f53c4aSTejun Heo if (cwq->nr_in_flight[color]) 170073f53c4aSTejun Heo return; 170173f53c4aSTejun Heo 170273f53c4aSTejun Heo /* this cwq is done, clear flush_color */ 170373f53c4aSTejun Heo cwq->flush_color = -1; 170473f53c4aSTejun Heo 170573f53c4aSTejun Heo /* 170673f53c4aSTejun Heo * If this was the last cwq, wake up the first flusher. It 170773f53c4aSTejun Heo * will handle the rest. 170873f53c4aSTejun Heo */ 170973f53c4aSTejun Heo if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) 171073f53c4aSTejun Heo complete(&cwq->wq->first_flusher->done); 171173f53c4aSTejun Heo } 171273f53c4aSTejun Heo 171373f53c4aSTejun Heo /** 1714a62428c0STejun Heo * process_one_work - process single work 1715c34056a3STejun Heo * @worker: self 1716a62428c0STejun Heo * @work: work to process 1717a62428c0STejun Heo * 1718a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 1719a62428c0STejun Heo * process a single work including synchronization against and 1720a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 1721a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 1722a62428c0STejun Heo * call this function to process a work. 1723a62428c0STejun Heo * 1724a62428c0STejun Heo * CONTEXT: 17258b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1726a62428c0STejun Heo */ 1727c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 17281da177e4SLinus Torvalds { 17297e11629dSTejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 17308b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 1731c8e55f36STejun Heo struct hlist_head *bwh = busy_worker_head(gcwq, work); 1732fb0e7bebSTejun Heo bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 17336bb49e59SDavid Howells work_func_t f = work->func; 173473f53c4aSTejun Heo int work_color; 17357e11629dSTejun Heo struct worker *collision; 17364e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 17374e6045f1SJohannes Berg /* 1738a62428c0STejun Heo * It is permissible to free the struct work_struct from 1739a62428c0STejun Heo * inside the function that is called from it, this we need to 1740a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 1741a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 1742a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 17434e6045f1SJohannes Berg */ 17444e6045f1SJohannes Berg struct lockdep_map lockdep_map = work->lockdep_map; 17454e6045f1SJohannes Berg #endif 17467e11629dSTejun Heo /* 17477e11629dSTejun Heo * A single work shouldn't be executed concurrently by 17487e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 17497e11629dSTejun Heo * already processing the work. If so, defer the work to the 17507e11629dSTejun Heo * currently executing one. 17517e11629dSTejun Heo */ 17527e11629dSTejun Heo collision = __find_worker_executing_work(gcwq, bwh, work); 17537e11629dSTejun Heo if (unlikely(collision)) { 17547e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 17557e11629dSTejun Heo return; 17567e11629dSTejun Heo } 17571da177e4SLinus Torvalds 1758a62428c0STejun Heo /* claim and process */ 17591da177e4SLinus Torvalds debug_work_deactivate(work); 1760c8e55f36STejun Heo hlist_add_head(&worker->hentry, bwh); 1761c34056a3STejun Heo worker->current_work = work; 17628cca0eeaSTejun Heo worker->current_cwq = cwq; 176373f53c4aSTejun Heo work_color = get_work_color(work); 17647a22ad75STejun Heo 17657a22ad75STejun Heo /* record the current cpu number in the work data and dequeue */ 17667a22ad75STejun Heo set_work_cpu(work, gcwq->cpu); 1767a62428c0STejun Heo list_del_init(&work->entry); 1768a62428c0STejun Heo 1769649027d7STejun Heo /* 1770649027d7STejun Heo * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, 1771649027d7STejun Heo * wake up another worker; otherwise, clear HIGHPRI_PENDING. 1772649027d7STejun Heo */ 1773649027d7STejun Heo if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { 1774649027d7STejun Heo struct work_struct *nwork = list_first_entry(&gcwq->worklist, 1775649027d7STejun Heo struct work_struct, entry); 1776649027d7STejun Heo 1777649027d7STejun Heo if (!list_empty(&gcwq->worklist) && 1778649027d7STejun Heo get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) 1779649027d7STejun Heo wake_up_worker(gcwq); 1780649027d7STejun Heo else 1781649027d7STejun Heo gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; 1782649027d7STejun Heo } 1783649027d7STejun Heo 1784fb0e7bebSTejun Heo /* 1785fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 1786fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 1787fb0e7bebSTejun Heo */ 1788fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1789fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 1790fb0e7bebSTejun Heo 17918b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 17921da177e4SLinus Torvalds 179323b2e599SOleg Nesterov work_clear_pending(work); 17943295f0efSIngo Molnar lock_map_acquire(&cwq->wq->lockdep_map); 17953295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 1796e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 179765f27f38SDavid Howells f(work); 1798e36c886aSArjan van de Ven /* 1799e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 1800e36c886aSArjan van de Ven * point will only record its address. 1801e36c886aSArjan van de Ven */ 1802e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 18033295f0efSIngo Molnar lock_map_release(&lockdep_map); 18043295f0efSIngo Molnar lock_map_release(&cwq->wq->lockdep_map); 18051da177e4SLinus Torvalds 1806d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 1807d5abe669SPeter Zijlstra printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " 1808d5abe669SPeter Zijlstra "%s/0x%08x/%d\n", 1809a62428c0STejun Heo current->comm, preempt_count(), task_pid_nr(current)); 1810d5abe669SPeter Zijlstra printk(KERN_ERR " last function: "); 1811d5abe669SPeter Zijlstra print_symbol("%s\n", (unsigned long)f); 1812d5abe669SPeter Zijlstra debug_show_held_locks(current); 1813d5abe669SPeter Zijlstra dump_stack(); 1814d5abe669SPeter Zijlstra } 1815d5abe669SPeter Zijlstra 18168b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1817a62428c0STejun Heo 1818fb0e7bebSTejun Heo /* clear cpu intensive status */ 1819fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 1820fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 1821fb0e7bebSTejun Heo 1822a62428c0STejun Heo /* we're done with it, release */ 1823c8e55f36STejun Heo hlist_del_init(&worker->hentry); 1824c34056a3STejun Heo worker->current_work = NULL; 18258cca0eeaSTejun Heo worker->current_cwq = NULL; 182673f53c4aSTejun Heo cwq_dec_nr_in_flight(cwq, work_color); 18271da177e4SLinus Torvalds } 18281da177e4SLinus Torvalds 1829affee4b2STejun Heo /** 1830affee4b2STejun Heo * process_scheduled_works - process scheduled works 1831affee4b2STejun Heo * @worker: self 1832affee4b2STejun Heo * 1833affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 1834affee4b2STejun Heo * may change while processing a work, so this function repeatedly 1835affee4b2STejun Heo * fetches a work from the top and executes it. 1836affee4b2STejun Heo * 1837affee4b2STejun Heo * CONTEXT: 18388b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 1839affee4b2STejun Heo * multiple times. 1840affee4b2STejun Heo */ 1841affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 18421da177e4SLinus Torvalds { 1843affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 1844affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 1845a62428c0STejun Heo struct work_struct, entry); 1846c34056a3STejun Heo process_one_work(worker, work); 1847a62428c0STejun Heo } 18481da177e4SLinus Torvalds } 18491da177e4SLinus Torvalds 18504690c4abSTejun Heo /** 18514690c4abSTejun Heo * worker_thread - the worker thread function 1852c34056a3STejun Heo * @__worker: self 18534690c4abSTejun Heo * 1854e22bee78STejun Heo * The gcwq worker thread function. There's a single dynamic pool of 1855e22bee78STejun Heo * these per each cpu. These workers process all works regardless of 1856e22bee78STejun Heo * their specific target workqueue. The only exception is works which 1857e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 1858e22bee78STejun Heo * rescuer_thread(). 18594690c4abSTejun Heo */ 1860c34056a3STejun Heo static int worker_thread(void *__worker) 18611da177e4SLinus Torvalds { 1862c34056a3STejun Heo struct worker *worker = __worker; 18638b03ae3cSTejun Heo struct global_cwq *gcwq = worker->gcwq; 18641da177e4SLinus Torvalds 1865e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 1866e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 1867c8e55f36STejun Heo woke_up: 18688b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1869affee4b2STejun Heo 1870c8e55f36STejun Heo /* DIE can be set only while we're idle, checking here is enough */ 1871c8e55f36STejun Heo if (worker->flags & WORKER_DIE) { 1872c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1873e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 1874c8e55f36STejun Heo return 0; 1875c8e55f36STejun Heo } 1876c8e55f36STejun Heo 1877c8e55f36STejun Heo worker_leave_idle(worker); 1878db7bccf4STejun Heo recheck: 1879e22bee78STejun Heo /* no more worker necessary? */ 1880e22bee78STejun Heo if (!need_more_worker(gcwq)) 1881e22bee78STejun Heo goto sleep; 1882e22bee78STejun Heo 1883e22bee78STejun Heo /* do we need to manage? */ 1884e22bee78STejun Heo if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) 1885e22bee78STejun Heo goto recheck; 1886e22bee78STejun Heo 1887c8e55f36STejun Heo /* 1888c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 1889c8e55f36STejun Heo * preparing to process a work or actually processing it. 1890c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 1891c8e55f36STejun Heo */ 1892c8e55f36STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1893c8e55f36STejun Heo 1894e22bee78STejun Heo /* 1895e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 1896e22bee78STejun Heo * at least one idle worker or that someone else has already 1897e22bee78STejun Heo * assumed the manager role. 1898e22bee78STejun Heo */ 1899e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 1900e22bee78STejun Heo 1901e22bee78STejun Heo do { 1902affee4b2STejun Heo struct work_struct *work = 19037e11629dSTejun Heo list_first_entry(&gcwq->worklist, 1904affee4b2STejun Heo struct work_struct, entry); 1905affee4b2STejun Heo 1906c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 1907affee4b2STejun Heo /* optimization path, not strictly necessary */ 1908affee4b2STejun Heo process_one_work(worker, work); 1909affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 1910affee4b2STejun Heo process_scheduled_works(worker); 1911affee4b2STejun Heo } else { 1912c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 1913affee4b2STejun Heo process_scheduled_works(worker); 1914affee4b2STejun Heo } 1915e22bee78STejun Heo } while (keep_working(gcwq)); 1916affee4b2STejun Heo 1917e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 1918d313dd85STejun Heo sleep: 1919e22bee78STejun Heo if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) 1920e22bee78STejun Heo goto recheck; 1921d313dd85STejun Heo 1922c8e55f36STejun Heo /* 1923e22bee78STejun Heo * gcwq->lock is held and there's no work to process and no 1924e22bee78STejun Heo * need to manage, sleep. Workers are woken up only while 1925e22bee78STejun Heo * holding gcwq->lock or from local cpu, so setting the 1926e22bee78STejun Heo * current state before releasing gcwq->lock is enough to 1927e22bee78STejun Heo * prevent losing any event. 1928c8e55f36STejun Heo */ 1929c8e55f36STejun Heo worker_enter_idle(worker); 1930c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 19318b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 19321da177e4SLinus Torvalds schedule(); 1933c8e55f36STejun Heo goto woke_up; 19341da177e4SLinus Torvalds } 19351da177e4SLinus Torvalds 1936e22bee78STejun Heo /** 1937e22bee78STejun Heo * rescuer_thread - the rescuer thread function 1938e22bee78STejun Heo * @__wq: the associated workqueue 1939e22bee78STejun Heo * 1940e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 1941e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 1942e22bee78STejun Heo * 1943e22bee78STejun Heo * Regular work processing on a gcwq may block trying to create a new 1944e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 1945e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 1946e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 1947e22bee78STejun Heo * the problem rescuer solves. 1948e22bee78STejun Heo * 1949e22bee78STejun Heo * When such condition is possible, the gcwq summons rescuers of all 1950e22bee78STejun Heo * workqueues which have works queued on the gcwq and let them process 1951e22bee78STejun Heo * those works so that forward progress can be guaranteed. 1952e22bee78STejun Heo * 1953e22bee78STejun Heo * This should happen rarely. 1954e22bee78STejun Heo */ 1955e22bee78STejun Heo static int rescuer_thread(void *__wq) 1956e22bee78STejun Heo { 1957e22bee78STejun Heo struct workqueue_struct *wq = __wq; 1958e22bee78STejun Heo struct worker *rescuer = wq->rescuer; 1959e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 1960f3421797STejun Heo bool is_unbound = wq->flags & WQ_UNBOUND; 1961e22bee78STejun Heo unsigned int cpu; 1962e22bee78STejun Heo 1963e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 1964e22bee78STejun Heo repeat: 1965e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 19661da177e4SLinus Torvalds 19671da177e4SLinus Torvalds if (kthread_should_stop()) 1968e22bee78STejun Heo return 0; 19691da177e4SLinus Torvalds 1970f3421797STejun Heo /* 1971f3421797STejun Heo * See whether any cpu is asking for help. Unbounded 1972f3421797STejun Heo * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. 1973f3421797STejun Heo */ 1974f2e005aaSTejun Heo for_each_mayday_cpu(cpu, wq->mayday_mask) { 1975f3421797STejun Heo unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 1976f3421797STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); 1977e22bee78STejun Heo struct global_cwq *gcwq = cwq->gcwq; 1978e22bee78STejun Heo struct work_struct *work, *n; 1979e22bee78STejun Heo 1980e22bee78STejun Heo __set_current_state(TASK_RUNNING); 1981f2e005aaSTejun Heo mayday_clear_cpu(cpu, wq->mayday_mask); 1982e22bee78STejun Heo 1983e22bee78STejun Heo /* migrate to the target cpu if possible */ 1984e22bee78STejun Heo rescuer->gcwq = gcwq; 1985e22bee78STejun Heo worker_maybe_bind_and_lock(rescuer); 1986e22bee78STejun Heo 1987e22bee78STejun Heo /* 1988e22bee78STejun Heo * Slurp in all works issued via this workqueue and 1989e22bee78STejun Heo * process'em. 1990e22bee78STejun Heo */ 1991e22bee78STejun Heo BUG_ON(!list_empty(&rescuer->scheduled)); 1992e22bee78STejun Heo list_for_each_entry_safe(work, n, &gcwq->worklist, entry) 1993e22bee78STejun Heo if (get_work_cwq(work) == cwq) 1994e22bee78STejun Heo move_linked_works(work, scheduled, &n); 1995e22bee78STejun Heo 1996e22bee78STejun Heo process_scheduled_works(rescuer); 1997e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 19981da177e4SLinus Torvalds } 19991da177e4SLinus Torvalds 2000e22bee78STejun Heo schedule(); 2001e22bee78STejun Heo goto repeat; 20021da177e4SLinus Torvalds } 20031da177e4SLinus Torvalds 2004fc2e4d70SOleg Nesterov struct wq_barrier { 2005fc2e4d70SOleg Nesterov struct work_struct work; 2006fc2e4d70SOleg Nesterov struct completion done; 2007fc2e4d70SOleg Nesterov }; 2008fc2e4d70SOleg Nesterov 2009fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2010fc2e4d70SOleg Nesterov { 2011fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2012fc2e4d70SOleg Nesterov complete(&barr->done); 2013fc2e4d70SOleg Nesterov } 2014fc2e4d70SOleg Nesterov 20154690c4abSTejun Heo /** 20164690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 20174690c4abSTejun Heo * @cwq: cwq to insert barrier into 20184690c4abSTejun Heo * @barr: wq_barrier to insert 2019affee4b2STejun Heo * @target: target work to attach @barr to 2020affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 20214690c4abSTejun Heo * 2022affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2023affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2024affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2025affee4b2STejun Heo * cpu. 2026affee4b2STejun Heo * 2027affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2028affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2029affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2030affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2031affee4b2STejun Heo * after a work with LINKED flag set. 2032affee4b2STejun Heo * 2033affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2034affee4b2STejun Heo * underneath us, so we can't reliably determine cwq from @target. 20354690c4abSTejun Heo * 20364690c4abSTejun Heo * CONTEXT: 20378b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 20384690c4abSTejun Heo */ 203983c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 2040affee4b2STejun Heo struct wq_barrier *barr, 2041affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2042fc2e4d70SOleg Nesterov { 2043affee4b2STejun Heo struct list_head *head; 2044affee4b2STejun Heo unsigned int linked = 0; 2045affee4b2STejun Heo 2046dc186ad7SThomas Gleixner /* 20478b03ae3cSTejun Heo * debugobject calls are safe here even with gcwq->lock locked 2048dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2049dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2050dc186ad7SThomas Gleixner * might deadlock. 2051dc186ad7SThomas Gleixner */ 2052dc186ad7SThomas Gleixner INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); 205322df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2054fc2e4d70SOleg Nesterov init_completion(&barr->done); 205583c22520SOleg Nesterov 2056affee4b2STejun Heo /* 2057affee4b2STejun Heo * If @target is currently being executed, schedule the 2058affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2059affee4b2STejun Heo */ 2060affee4b2STejun Heo if (worker) 2061affee4b2STejun Heo head = worker->scheduled.next; 2062affee4b2STejun Heo else { 2063affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2064affee4b2STejun Heo 2065affee4b2STejun Heo head = target->entry.next; 2066affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2067affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2068affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2069affee4b2STejun Heo } 2070affee4b2STejun Heo 2071dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2072affee4b2STejun Heo insert_work(cwq, &barr->work, head, 2073affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2074fc2e4d70SOleg Nesterov } 2075fc2e4d70SOleg Nesterov 207673f53c4aSTejun Heo /** 207773f53c4aSTejun Heo * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing 207873f53c4aSTejun Heo * @wq: workqueue being flushed 207973f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 208073f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 208173f53c4aSTejun Heo * 208273f53c4aSTejun Heo * Prepare cwqs for workqueue flushing. 208373f53c4aSTejun Heo * 208473f53c4aSTejun Heo * If @flush_color is non-negative, flush_color on all cwqs should be 208573f53c4aSTejun Heo * -1. If no cwq has in-flight commands at the specified color, all 208673f53c4aSTejun Heo * cwq->flush_color's stay at -1 and %false is returned. If any cwq 208773f53c4aSTejun Heo * has in flight commands, its cwq->flush_color is set to 208873f53c4aSTejun Heo * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq 208973f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 209073f53c4aSTejun Heo * 209173f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 209273f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 209373f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 209473f53c4aSTejun Heo * is returned. 209573f53c4aSTejun Heo * 209673f53c4aSTejun Heo * If @work_color is non-negative, all cwqs should have the same 209773f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 209873f53c4aSTejun Heo * advanced to @work_color. 209973f53c4aSTejun Heo * 210073f53c4aSTejun Heo * CONTEXT: 210173f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 210273f53c4aSTejun Heo * 210373f53c4aSTejun Heo * RETURNS: 210473f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 210573f53c4aSTejun Heo * otherwise. 210673f53c4aSTejun Heo */ 210773f53c4aSTejun Heo static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, 210873f53c4aSTejun Heo int flush_color, int work_color) 21091da177e4SLinus Torvalds { 211073f53c4aSTejun Heo bool wait = false; 211173f53c4aSTejun Heo unsigned int cpu; 21121da177e4SLinus Torvalds 211373f53c4aSTejun Heo if (flush_color >= 0) { 211473f53c4aSTejun Heo BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); 211573f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 1); 2116dc186ad7SThomas Gleixner } 211714441960SOleg Nesterov 2118f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 211973f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 21208b03ae3cSTejun Heo struct global_cwq *gcwq = cwq->gcwq; 21211da177e4SLinus Torvalds 21228b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 212373f53c4aSTejun Heo 212473f53c4aSTejun Heo if (flush_color >= 0) { 212573f53c4aSTejun Heo BUG_ON(cwq->flush_color != -1); 212673f53c4aSTejun Heo 212773f53c4aSTejun Heo if (cwq->nr_in_flight[flush_color]) { 212873f53c4aSTejun Heo cwq->flush_color = flush_color; 212973f53c4aSTejun Heo atomic_inc(&wq->nr_cwqs_to_flush); 213073f53c4aSTejun Heo wait = true; 21311da177e4SLinus Torvalds } 213273f53c4aSTejun Heo } 213373f53c4aSTejun Heo 213473f53c4aSTejun Heo if (work_color >= 0) { 213573f53c4aSTejun Heo BUG_ON(work_color != work_next_color(cwq->work_color)); 213673f53c4aSTejun Heo cwq->work_color = work_color; 213773f53c4aSTejun Heo } 213873f53c4aSTejun Heo 21398b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 21401da177e4SLinus Torvalds } 21411da177e4SLinus Torvalds 214273f53c4aSTejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) 214373f53c4aSTejun Heo complete(&wq->first_flusher->done); 214473f53c4aSTejun Heo 214573f53c4aSTejun Heo return wait; 214683c22520SOleg Nesterov } 21471da177e4SLinus Torvalds 21480fcb78c2SRolf Eike Beer /** 21491da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 21500fcb78c2SRolf Eike Beer * @wq: workqueue to flush 21511da177e4SLinus Torvalds * 21521da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 21531da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 21541da177e4SLinus Torvalds * 2155fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2156fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 21571da177e4SLinus Torvalds */ 21587ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 21591da177e4SLinus Torvalds { 216073f53c4aSTejun Heo struct wq_flusher this_flusher = { 216173f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 216273f53c4aSTejun Heo .flush_color = -1, 216373f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 216473f53c4aSTejun Heo }; 216573f53c4aSTejun Heo int next_color; 2166b1f4ec17SOleg Nesterov 21673295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 21683295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 216973f53c4aSTejun Heo 217073f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 217173f53c4aSTejun Heo 217273f53c4aSTejun Heo /* 217373f53c4aSTejun Heo * Start-to-wait phase 217473f53c4aSTejun Heo */ 217573f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 217673f53c4aSTejun Heo 217773f53c4aSTejun Heo if (next_color != wq->flush_color) { 217873f53c4aSTejun Heo /* 217973f53c4aSTejun Heo * Color space is not full. The current work_color 218073f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 218173f53c4aSTejun Heo * by one. 218273f53c4aSTejun Heo */ 218373f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow)); 218473f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 218573f53c4aSTejun Heo wq->work_color = next_color; 218673f53c4aSTejun Heo 218773f53c4aSTejun Heo if (!wq->first_flusher) { 218873f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 218973f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 219073f53c4aSTejun Heo 219173f53c4aSTejun Heo wq->first_flusher = &this_flusher; 219273f53c4aSTejun Heo 219373f53c4aSTejun Heo if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, 219473f53c4aSTejun Heo wq->work_color)) { 219573f53c4aSTejun Heo /* nothing to flush, done */ 219673f53c4aSTejun Heo wq->flush_color = next_color; 219773f53c4aSTejun Heo wq->first_flusher = NULL; 219873f53c4aSTejun Heo goto out_unlock; 219973f53c4aSTejun Heo } 220073f53c4aSTejun Heo } else { 220173f53c4aSTejun Heo /* wait in queue */ 220273f53c4aSTejun Heo BUG_ON(wq->flush_color == this_flusher.flush_color); 220373f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 220473f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 220573f53c4aSTejun Heo } 220673f53c4aSTejun Heo } else { 220773f53c4aSTejun Heo /* 220873f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 220973f53c4aSTejun Heo * The next flush completion will assign us 221073f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 221173f53c4aSTejun Heo */ 221273f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 221373f53c4aSTejun Heo } 221473f53c4aSTejun Heo 221573f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 221673f53c4aSTejun Heo 221773f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 221873f53c4aSTejun Heo 221973f53c4aSTejun Heo /* 222073f53c4aSTejun Heo * Wake-up-and-cascade phase 222173f53c4aSTejun Heo * 222273f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 222373f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 222473f53c4aSTejun Heo */ 222573f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 222673f53c4aSTejun Heo return; 222773f53c4aSTejun Heo 222873f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 222973f53c4aSTejun Heo 22304ce48b37STejun Heo /* we might have raced, check again with mutex held */ 22314ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 22324ce48b37STejun Heo goto out_unlock; 22334ce48b37STejun Heo 223473f53c4aSTejun Heo wq->first_flusher = NULL; 223573f53c4aSTejun Heo 223673f53c4aSTejun Heo BUG_ON(!list_empty(&this_flusher.list)); 223773f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 223873f53c4aSTejun Heo 223973f53c4aSTejun Heo while (true) { 224073f53c4aSTejun Heo struct wq_flusher *next, *tmp; 224173f53c4aSTejun Heo 224273f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 224373f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 224473f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 224573f53c4aSTejun Heo break; 224673f53c4aSTejun Heo list_del_init(&next->list); 224773f53c4aSTejun Heo complete(&next->done); 224873f53c4aSTejun Heo } 224973f53c4aSTejun Heo 225073f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow) && 225173f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 225273f53c4aSTejun Heo 225373f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 225473f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 225573f53c4aSTejun Heo 225673f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 225773f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 225873f53c4aSTejun Heo /* 225973f53c4aSTejun Heo * Assign the same color to all overflowed 226073f53c4aSTejun Heo * flushers, advance work_color and append to 226173f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 226273f53c4aSTejun Heo * phase for these overflowed flushers. 226373f53c4aSTejun Heo */ 226473f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 226573f53c4aSTejun Heo tmp->flush_color = wq->work_color; 226673f53c4aSTejun Heo 226773f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 226873f53c4aSTejun Heo 226973f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 227073f53c4aSTejun Heo &wq->flusher_queue); 227173f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 227273f53c4aSTejun Heo } 227373f53c4aSTejun Heo 227473f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 227573f53c4aSTejun Heo BUG_ON(wq->flush_color != wq->work_color); 227673f53c4aSTejun Heo break; 227773f53c4aSTejun Heo } 227873f53c4aSTejun Heo 227973f53c4aSTejun Heo /* 228073f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 228173f53c4aSTejun Heo * the new first flusher and arm cwqs. 228273f53c4aSTejun Heo */ 228373f53c4aSTejun Heo BUG_ON(wq->flush_color == wq->work_color); 228473f53c4aSTejun Heo BUG_ON(wq->flush_color != next->flush_color); 228573f53c4aSTejun Heo 228673f53c4aSTejun Heo list_del_init(&next->list); 228773f53c4aSTejun Heo wq->first_flusher = next; 228873f53c4aSTejun Heo 228973f53c4aSTejun Heo if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) 229073f53c4aSTejun Heo break; 229173f53c4aSTejun Heo 229273f53c4aSTejun Heo /* 229373f53c4aSTejun Heo * Meh... this color is already done, clear first 229473f53c4aSTejun Heo * flusher and repeat cascading. 229573f53c4aSTejun Heo */ 229673f53c4aSTejun Heo wq->first_flusher = NULL; 229773f53c4aSTejun Heo } 229873f53c4aSTejun Heo 229973f53c4aSTejun Heo out_unlock: 230073f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 23011da177e4SLinus Torvalds } 2302ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 23031da177e4SLinus Torvalds 2304db700897SOleg Nesterov /** 2305db700897SOleg Nesterov * flush_work - block until a work_struct's callback has terminated 2306db700897SOleg Nesterov * @work: the work which is to be flushed 2307db700897SOleg Nesterov * 2308a67da70dSOleg Nesterov * Returns false if @work has already terminated. 2309a67da70dSOleg Nesterov * 2310db700897SOleg Nesterov * It is expected that, prior to calling flush_work(), the caller has 2311db700897SOleg Nesterov * arranged for the work to not be requeued, otherwise it doesn't make 2312db700897SOleg Nesterov * sense to use this function. 2313db700897SOleg Nesterov */ 2314db700897SOleg Nesterov int flush_work(struct work_struct *work) 2315db700897SOleg Nesterov { 2316affee4b2STejun Heo struct worker *worker = NULL; 23178b03ae3cSTejun Heo struct global_cwq *gcwq; 2318db700897SOleg Nesterov struct cpu_workqueue_struct *cwq; 2319db700897SOleg Nesterov struct wq_barrier barr; 2320db700897SOleg Nesterov 2321db700897SOleg Nesterov might_sleep(); 23227a22ad75STejun Heo gcwq = get_work_gcwq(work); 23237a22ad75STejun Heo if (!gcwq) 2324db700897SOleg Nesterov return 0; 2325db700897SOleg Nesterov 23268b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2327db700897SOleg Nesterov if (!list_empty(&work->entry)) { 2328db700897SOleg Nesterov /* 2329db700897SOleg Nesterov * See the comment near try_to_grab_pending()->smp_rmb(). 23307a22ad75STejun Heo * If it was re-queued to a different gcwq under us, we 23317a22ad75STejun Heo * are not going to wait. 2332db700897SOleg Nesterov */ 2333db700897SOleg Nesterov smp_rmb(); 23347a22ad75STejun Heo cwq = get_work_cwq(work); 23357a22ad75STejun Heo if (unlikely(!cwq || gcwq != cwq->gcwq)) 23364690c4abSTejun Heo goto already_gone; 2337db700897SOleg Nesterov } else { 23387a22ad75STejun Heo worker = find_worker_executing_work(gcwq, work); 2339affee4b2STejun Heo if (!worker) 23404690c4abSTejun Heo goto already_gone; 23417a22ad75STejun Heo cwq = worker->current_cwq; 2342db700897SOleg Nesterov } 2343db700897SOleg Nesterov 2344affee4b2STejun Heo insert_wq_barrier(cwq, &barr, work, worker); 23458b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23467a22ad75STejun Heo 2347db700897SOleg Nesterov lock_map_acquire(&cwq->wq->lockdep_map); 2348db700897SOleg Nesterov lock_map_release(&cwq->wq->lockdep_map); 2349db700897SOleg Nesterov 2350db700897SOleg Nesterov wait_for_completion(&barr.done); 2351dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2352db700897SOleg Nesterov return 1; 23534690c4abSTejun Heo already_gone: 23548b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23554690c4abSTejun Heo return 0; 2356db700897SOleg Nesterov } 2357db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2358db700897SOleg Nesterov 23596e84d644SOleg Nesterov /* 23601f1f642eSOleg Nesterov * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, 23616e84d644SOleg Nesterov * so this work can't be re-armed in any way. 23626e84d644SOleg Nesterov */ 23636e84d644SOleg Nesterov static int try_to_grab_pending(struct work_struct *work) 23646e84d644SOleg Nesterov { 23658b03ae3cSTejun Heo struct global_cwq *gcwq; 23661f1f642eSOleg Nesterov int ret = -1; 23676e84d644SOleg Nesterov 236822df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 23691f1f642eSOleg Nesterov return 0; 23706e84d644SOleg Nesterov 23716e84d644SOleg Nesterov /* 23726e84d644SOleg Nesterov * The queueing is in progress, or it is already queued. Try to 23736e84d644SOleg Nesterov * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 23746e84d644SOleg Nesterov */ 23757a22ad75STejun Heo gcwq = get_work_gcwq(work); 23767a22ad75STejun Heo if (!gcwq) 23776e84d644SOleg Nesterov return ret; 23786e84d644SOleg Nesterov 23798b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 23806e84d644SOleg Nesterov if (!list_empty(&work->entry)) { 23816e84d644SOleg Nesterov /* 23827a22ad75STejun Heo * This work is queued, but perhaps we locked the wrong gcwq. 23836e84d644SOleg Nesterov * In that case we must see the new value after rmb(), see 23846e84d644SOleg Nesterov * insert_work()->wmb(). 23856e84d644SOleg Nesterov */ 23866e84d644SOleg Nesterov smp_rmb(); 23877a22ad75STejun Heo if (gcwq == get_work_gcwq(work)) { 2388dc186ad7SThomas Gleixner debug_work_deactivate(work); 23896e84d644SOleg Nesterov list_del_init(&work->entry); 23907a22ad75STejun Heo cwq_dec_nr_in_flight(get_work_cwq(work), 23917a22ad75STejun Heo get_work_color(work)); 23926e84d644SOleg Nesterov ret = 1; 23936e84d644SOleg Nesterov } 23946e84d644SOleg Nesterov } 23958b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23966e84d644SOleg Nesterov 23976e84d644SOleg Nesterov return ret; 23986e84d644SOleg Nesterov } 23996e84d644SOleg Nesterov 24007a22ad75STejun Heo static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) 2401b89deed3SOleg Nesterov { 2402b89deed3SOleg Nesterov struct wq_barrier barr; 2403affee4b2STejun Heo struct worker *worker; 2404b89deed3SOleg Nesterov 24058b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2406b89deed3SOleg Nesterov 24077a22ad75STejun Heo worker = find_worker_executing_work(gcwq, work); 24087a22ad75STejun Heo if (unlikely(worker)) 24097a22ad75STejun Heo insert_wq_barrier(worker->current_cwq, &barr, work, worker); 2410affee4b2STejun Heo 24118b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 2412b89deed3SOleg Nesterov 2413affee4b2STejun Heo if (unlikely(worker)) { 2414b89deed3SOleg Nesterov wait_for_completion(&barr.done); 2415dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2416dc186ad7SThomas Gleixner } 2417b89deed3SOleg Nesterov } 2418b89deed3SOleg Nesterov 24196e84d644SOleg Nesterov static void wait_on_work(struct work_struct *work) 2420b89deed3SOleg Nesterov { 2421b1f4ec17SOleg Nesterov int cpu; 2422b89deed3SOleg Nesterov 2423f293ea92SOleg Nesterov might_sleep(); 2424f293ea92SOleg Nesterov 24253295f0efSIngo Molnar lock_map_acquire(&work->lockdep_map); 24263295f0efSIngo Molnar lock_map_release(&work->lockdep_map); 24274e6045f1SJohannes Berg 2428f3421797STejun Heo for_each_gcwq_cpu(cpu) 24297a22ad75STejun Heo wait_on_cpu_work(get_gcwq(cpu), work); 24306e84d644SOleg Nesterov } 24316e84d644SOleg Nesterov 24321f1f642eSOleg Nesterov static int __cancel_work_timer(struct work_struct *work, 24331f1f642eSOleg Nesterov struct timer_list* timer) 24341f1f642eSOleg Nesterov { 24351f1f642eSOleg Nesterov int ret; 24361f1f642eSOleg Nesterov 24371f1f642eSOleg Nesterov do { 24381f1f642eSOleg Nesterov ret = (timer && likely(del_timer(timer))); 24391f1f642eSOleg Nesterov if (!ret) 24401f1f642eSOleg Nesterov ret = try_to_grab_pending(work); 24411f1f642eSOleg Nesterov wait_on_work(work); 24421f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 24431f1f642eSOleg Nesterov 24447a22ad75STejun Heo clear_work_data(work); 24451f1f642eSOleg Nesterov return ret; 24461f1f642eSOleg Nesterov } 24471f1f642eSOleg Nesterov 24486e84d644SOleg Nesterov /** 24496e84d644SOleg Nesterov * cancel_work_sync - block until a work_struct's callback has terminated 24506e84d644SOleg Nesterov * @work: the work which is to be flushed 24516e84d644SOleg Nesterov * 24521f1f642eSOleg Nesterov * Returns true if @work was pending. 24531f1f642eSOleg Nesterov * 24546e84d644SOleg Nesterov * cancel_work_sync() will cancel the work if it is queued. If the work's 24556e84d644SOleg Nesterov * callback appears to be running, cancel_work_sync() will block until it 24566e84d644SOleg Nesterov * has completed. 24576e84d644SOleg Nesterov * 24586e84d644SOleg Nesterov * It is possible to use this function if the work re-queues itself. It can 24596e84d644SOleg Nesterov * cancel the work even if it migrates to another workqueue, however in that 24606e84d644SOleg Nesterov * case it only guarantees that work->func() has completed on the last queued 24616e84d644SOleg Nesterov * workqueue. 24626e84d644SOleg Nesterov * 24636e84d644SOleg Nesterov * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not 24646e84d644SOleg Nesterov * pending, otherwise it goes into a busy-wait loop until the timer expires. 24656e84d644SOleg Nesterov * 24666e84d644SOleg Nesterov * The caller must ensure that workqueue_struct on which this work was last 24676e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 24686e84d644SOleg Nesterov */ 24691f1f642eSOleg Nesterov int cancel_work_sync(struct work_struct *work) 24706e84d644SOleg Nesterov { 24711f1f642eSOleg Nesterov return __cancel_work_timer(work, NULL); 2472b89deed3SOleg Nesterov } 247328e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2474b89deed3SOleg Nesterov 24756e84d644SOleg Nesterov /** 2476f5a421a4SOleg Nesterov * cancel_delayed_work_sync - reliably kill off a delayed work. 24776e84d644SOleg Nesterov * @dwork: the delayed work struct 24786e84d644SOleg Nesterov * 24791f1f642eSOleg Nesterov * Returns true if @dwork was pending. 24801f1f642eSOleg Nesterov * 24816e84d644SOleg Nesterov * It is possible to use this function if @dwork rearms itself via queue_work() 24826e84d644SOleg Nesterov * or queue_delayed_work(). See also the comment for cancel_work_sync(). 24836e84d644SOleg Nesterov */ 24841f1f642eSOleg Nesterov int cancel_delayed_work_sync(struct delayed_work *dwork) 24856e84d644SOleg Nesterov { 24861f1f642eSOleg Nesterov return __cancel_work_timer(&dwork->work, &dwork->timer); 24876e84d644SOleg Nesterov } 2488f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 24891da177e4SLinus Torvalds 24900fcb78c2SRolf Eike Beer /** 24910fcb78c2SRolf Eike Beer * schedule_work - put work task in global workqueue 24920fcb78c2SRolf Eike Beer * @work: job to be done 24930fcb78c2SRolf Eike Beer * 24945b0f437dSBart Van Assche * Returns zero if @work was already on the kernel-global workqueue and 24955b0f437dSBart Van Assche * non-zero otherwise. 24965b0f437dSBart Van Assche * 24975b0f437dSBart Van Assche * This puts a job in the kernel-global workqueue if it was not already 24985b0f437dSBart Van Assche * queued and leaves it in the same position on the kernel-global 24995b0f437dSBart Van Assche * workqueue otherwise. 25000fcb78c2SRolf Eike Beer */ 25017ad5b3a5SHarvey Harrison int schedule_work(struct work_struct *work) 25021da177e4SLinus Torvalds { 2503d320c038STejun Heo return queue_work(system_wq, work); 25041da177e4SLinus Torvalds } 2505ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_work); 25061da177e4SLinus Torvalds 2507c1a220e7SZhang Rui /* 2508c1a220e7SZhang Rui * schedule_work_on - put work task on a specific cpu 2509c1a220e7SZhang Rui * @cpu: cpu to put the work task on 2510c1a220e7SZhang Rui * @work: job to be done 2511c1a220e7SZhang Rui * 2512c1a220e7SZhang Rui * This puts a job on a specific cpu 2513c1a220e7SZhang Rui */ 2514c1a220e7SZhang Rui int schedule_work_on(int cpu, struct work_struct *work) 2515c1a220e7SZhang Rui { 2516d320c038STejun Heo return queue_work_on(cpu, system_wq, work); 2517c1a220e7SZhang Rui } 2518c1a220e7SZhang Rui EXPORT_SYMBOL(schedule_work_on); 2519c1a220e7SZhang Rui 25200fcb78c2SRolf Eike Beer /** 25210fcb78c2SRolf Eike Beer * schedule_delayed_work - put work task in global workqueue after delay 252252bad64dSDavid Howells * @dwork: job to be done 252352bad64dSDavid Howells * @delay: number of jiffies to wait or 0 for immediate execution 25240fcb78c2SRolf Eike Beer * 25250fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 25260fcb78c2SRolf Eike Beer * workqueue. 25270fcb78c2SRolf Eike Beer */ 25287ad5b3a5SHarvey Harrison int schedule_delayed_work(struct delayed_work *dwork, 252982f67cd9SIngo Molnar unsigned long delay) 25301da177e4SLinus Torvalds { 2531d320c038STejun Heo return queue_delayed_work(system_wq, dwork, delay); 25321da177e4SLinus Torvalds } 2533ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work); 25341da177e4SLinus Torvalds 25350fcb78c2SRolf Eike Beer /** 25368c53e463SLinus Torvalds * flush_delayed_work - block until a dwork_struct's callback has terminated 25378c53e463SLinus Torvalds * @dwork: the delayed work which is to be flushed 25388c53e463SLinus Torvalds * 25398c53e463SLinus Torvalds * Any timeout is cancelled, and any pending work is run immediately. 25408c53e463SLinus Torvalds */ 25418c53e463SLinus Torvalds void flush_delayed_work(struct delayed_work *dwork) 25428c53e463SLinus Torvalds { 25438c53e463SLinus Torvalds if (del_timer_sync(&dwork->timer)) { 25447a22ad75STejun Heo __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq, 25454690c4abSTejun Heo &dwork->work); 25468c53e463SLinus Torvalds put_cpu(); 25478c53e463SLinus Torvalds } 25488c53e463SLinus Torvalds flush_work(&dwork->work); 25498c53e463SLinus Torvalds } 25508c53e463SLinus Torvalds EXPORT_SYMBOL(flush_delayed_work); 25518c53e463SLinus Torvalds 25528c53e463SLinus Torvalds /** 25530fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 25540fcb78c2SRolf Eike Beer * @cpu: cpu to use 255552bad64dSDavid Howells * @dwork: job to be done 25560fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 25570fcb78c2SRolf Eike Beer * 25580fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 25590fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 25600fcb78c2SRolf Eike Beer */ 25611da177e4SLinus Torvalds int schedule_delayed_work_on(int cpu, 256252bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 25631da177e4SLinus Torvalds { 2564d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 25651da177e4SLinus Torvalds } 2566ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 25671da177e4SLinus Torvalds 2568b6136773SAndrew Morton /** 2569b6136773SAndrew Morton * schedule_on_each_cpu - call a function on each online CPU from keventd 2570b6136773SAndrew Morton * @func: the function to call 2571b6136773SAndrew Morton * 2572b6136773SAndrew Morton * Returns zero on success. 2573b6136773SAndrew Morton * Returns -ve errno on failure. 2574b6136773SAndrew Morton * 2575b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 2576b6136773SAndrew Morton */ 257765f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 257815316ba8SChristoph Lameter { 257915316ba8SChristoph Lameter int cpu; 258038f51568SNamhyung Kim struct work_struct __percpu *works; 258115316ba8SChristoph Lameter 2582b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 2583b6136773SAndrew Morton if (!works) 258415316ba8SChristoph Lameter return -ENOMEM; 2585b6136773SAndrew Morton 258695402b38SGautham R Shenoy get_online_cpus(); 258793981800STejun Heo 258815316ba8SChristoph Lameter for_each_online_cpu(cpu) { 25899bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 25909bfb1839SIngo Molnar 25919bfb1839SIngo Molnar INIT_WORK(work, func); 25928de6d308SOleg Nesterov schedule_work_on(cpu, work); 259315316ba8SChristoph Lameter } 259493981800STejun Heo 259593981800STejun Heo for_each_online_cpu(cpu) 25968616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 259793981800STejun Heo 259895402b38SGautham R Shenoy put_online_cpus(); 2599b6136773SAndrew Morton free_percpu(works); 260015316ba8SChristoph Lameter return 0; 260115316ba8SChristoph Lameter } 260215316ba8SChristoph Lameter 2603eef6a7d5SAlan Stern /** 2604eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 2605eef6a7d5SAlan Stern * 2606eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 2607eef6a7d5SAlan Stern * completion. 2608eef6a7d5SAlan Stern * 2609eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 2610eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 2611eef6a7d5SAlan Stern * will lead to deadlock: 2612eef6a7d5SAlan Stern * 2613eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 2614eef6a7d5SAlan Stern * a lock held by your code or its caller. 2615eef6a7d5SAlan Stern * 2616eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 2617eef6a7d5SAlan Stern * 2618eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 2619eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 2620eef6a7d5SAlan Stern * what locks they need, which you have no control over. 2621eef6a7d5SAlan Stern * 2622eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 2623eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 2624eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 2625eef6a7d5SAlan Stern * cancel_work_sync() instead. 2626eef6a7d5SAlan Stern */ 26271da177e4SLinus Torvalds void flush_scheduled_work(void) 26281da177e4SLinus Torvalds { 2629d320c038STejun Heo flush_workqueue(system_wq); 26301da177e4SLinus Torvalds } 2631ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 26321da177e4SLinus Torvalds 26331da177e4SLinus Torvalds /** 26341fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 26351fa44ecaSJames Bottomley * @fn: the function to execute 26361fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 26371fa44ecaSJames Bottomley * be available when the work executes) 26381fa44ecaSJames Bottomley * 26391fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 26401fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 26411fa44ecaSJames Bottomley * 26421fa44ecaSJames Bottomley * Returns: 0 - function was executed 26431fa44ecaSJames Bottomley * 1 - function was scheduled for execution 26441fa44ecaSJames Bottomley */ 264565f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 26461fa44ecaSJames Bottomley { 26471fa44ecaSJames Bottomley if (!in_interrupt()) { 264865f27f38SDavid Howells fn(&ew->work); 26491fa44ecaSJames Bottomley return 0; 26501fa44ecaSJames Bottomley } 26511fa44ecaSJames Bottomley 265265f27f38SDavid Howells INIT_WORK(&ew->work, fn); 26531fa44ecaSJames Bottomley schedule_work(&ew->work); 26541fa44ecaSJames Bottomley 26551fa44ecaSJames Bottomley return 1; 26561fa44ecaSJames Bottomley } 26571fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 26581fa44ecaSJames Bottomley 26591da177e4SLinus Torvalds int keventd_up(void) 26601da177e4SLinus Torvalds { 2661d320c038STejun Heo return system_wq != NULL; 26621da177e4SLinus Torvalds } 26631da177e4SLinus Torvalds 2664bdbc5dd7STejun Heo static int alloc_cwqs(struct workqueue_struct *wq) 26651da177e4SLinus Torvalds { 26663af24433SOleg Nesterov /* 26670f900049STejun Heo * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. 26680f900049STejun Heo * Make sure that the alignment isn't lower than that of 26690f900049STejun Heo * unsigned long long. 26703af24433SOleg Nesterov */ 26710f900049STejun Heo const size_t size = sizeof(struct cpu_workqueue_struct); 26720f900049STejun Heo const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, 26730f900049STejun Heo __alignof__(unsigned long long)); 2674931ac77eSTejun Heo #ifdef CONFIG_SMP 2675931ac77eSTejun Heo bool percpu = !(wq->flags & WQ_UNBOUND); 2676931ac77eSTejun Heo #else 2677931ac77eSTejun Heo bool percpu = false; 2678931ac77eSTejun Heo #endif 26793af24433SOleg Nesterov 2680931ac77eSTejun Heo if (percpu) 2681f3421797STejun Heo wq->cpu_wq.pcpu = __alloc_percpu(size, align); 2682931ac77eSTejun Heo else { 26830f900049STejun Heo void *ptr; 2684e1d8aa9fSFrederic Weisbecker 26850f900049STejun Heo /* 2686f3421797STejun Heo * Allocate enough room to align cwq and put an extra 2687f3421797STejun Heo * pointer at the end pointing back to the originally 2688f3421797STejun Heo * allocated pointer which will be used for free. 26890f900049STejun Heo */ 2690bdbc5dd7STejun Heo ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); 2691bdbc5dd7STejun Heo if (ptr) { 2692bdbc5dd7STejun Heo wq->cpu_wq.single = PTR_ALIGN(ptr, align); 2693bdbc5dd7STejun Heo *(void **)(wq->cpu_wq.single + 1) = ptr; 2694bdbc5dd7STejun Heo } 26953af24433SOleg Nesterov } 26963af24433SOleg Nesterov 26970f900049STejun Heo /* just in case, make sure it's actually aligned */ 2698bdbc5dd7STejun Heo BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); 2699bdbc5dd7STejun Heo return wq->cpu_wq.v ? 0 : -ENOMEM; 27000f900049STejun Heo } 27010f900049STejun Heo 2702bdbc5dd7STejun Heo static void free_cwqs(struct workqueue_struct *wq) 270306ba38a9SOleg Nesterov { 2704931ac77eSTejun Heo #ifdef CONFIG_SMP 2705931ac77eSTejun Heo bool percpu = !(wq->flags & WQ_UNBOUND); 2706931ac77eSTejun Heo #else 2707931ac77eSTejun Heo bool percpu = false; 2708931ac77eSTejun Heo #endif 270906ba38a9SOleg Nesterov 2710931ac77eSTejun Heo if (percpu) 2711bdbc5dd7STejun Heo free_percpu(wq->cpu_wq.pcpu); 2712f3421797STejun Heo else if (wq->cpu_wq.single) { 2713f3421797STejun Heo /* the pointer to free is stored right after the cwq */ 2714f3421797STejun Heo kfree(*(void **)(wq->cpu_wq.single + 1)); 271506ba38a9SOleg Nesterov } 271606ba38a9SOleg Nesterov } 271706ba38a9SOleg Nesterov 2718f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 2719f3421797STejun Heo const char *name) 2720b71ab8c2STejun Heo { 2721f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 2722f3421797STejun Heo 2723f3421797STejun Heo if (max_active < 1 || max_active > lim) 2724b71ab8c2STejun Heo printk(KERN_WARNING "workqueue: max_active %d requested for %s " 2725b71ab8c2STejun Heo "is out of range, clamping between %d and %d\n", 2726f3421797STejun Heo max_active, name, 1, lim); 2727b71ab8c2STejun Heo 2728f3421797STejun Heo return clamp_val(max_active, 1, lim); 2729b71ab8c2STejun Heo } 2730b71ab8c2STejun Heo 2731d320c038STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *name, 273297e37d7bSTejun Heo unsigned int flags, 27331e19ffc6STejun Heo int max_active, 2734eb13ba87SJohannes Berg struct lock_class_key *key, 2735eb13ba87SJohannes Berg const char *lock_name) 27363af24433SOleg Nesterov { 27373af24433SOleg Nesterov struct workqueue_struct *wq; 2738c34056a3STejun Heo unsigned int cpu; 27393af24433SOleg Nesterov 2740f3421797STejun Heo /* 2741f3421797STejun Heo * Unbound workqueues aren't concurrency managed and should be 2742f3421797STejun Heo * dispatched to workers immediately. 2743f3421797STejun Heo */ 2744f3421797STejun Heo if (flags & WQ_UNBOUND) 2745f3421797STejun Heo flags |= WQ_HIGHPRI; 2746f3421797STejun Heo 2747d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 2748f3421797STejun Heo max_active = wq_clamp_max_active(max_active, flags, name); 27493af24433SOleg Nesterov 27503af24433SOleg Nesterov wq = kzalloc(sizeof(*wq), GFP_KERNEL); 27513af24433SOleg Nesterov if (!wq) 27524690c4abSTejun Heo goto err; 27533af24433SOleg Nesterov 275497e37d7bSTejun Heo wq->flags = flags; 2755a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 275673f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 275773f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 0); 275873f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 275973f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 27603af24433SOleg Nesterov 27613af24433SOleg Nesterov wq->name = name; 2762eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 2763cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 27643af24433SOleg Nesterov 2765bdbc5dd7STejun Heo if (alloc_cwqs(wq) < 0) 2766bdbc5dd7STejun Heo goto err; 2767bdbc5dd7STejun Heo 2768f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 27691537663fSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 27708b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 27711537663fSTejun Heo 27720f900049STejun Heo BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 27738b03ae3cSTejun Heo cwq->gcwq = gcwq; 2774c34056a3STejun Heo cwq->wq = wq; 277573f53c4aSTejun Heo cwq->flush_color = -1; 27761e19ffc6STejun Heo cwq->max_active = max_active; 27771e19ffc6STejun Heo INIT_LIST_HEAD(&cwq->delayed_works); 2778e22bee78STejun Heo } 27791537663fSTejun Heo 2780e22bee78STejun Heo if (flags & WQ_RESCUER) { 2781e22bee78STejun Heo struct worker *rescuer; 2782e22bee78STejun Heo 2783f2e005aaSTejun Heo if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) 2784e22bee78STejun Heo goto err; 2785e22bee78STejun Heo 2786e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 2787e22bee78STejun Heo if (!rescuer) 2788e22bee78STejun Heo goto err; 2789e22bee78STejun Heo 2790e22bee78STejun Heo rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); 2791e22bee78STejun Heo if (IS_ERR(rescuer->task)) 2792e22bee78STejun Heo goto err; 2793e22bee78STejun Heo 2794e22bee78STejun Heo wq->rescuer = rescuer; 2795e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 2796e22bee78STejun Heo wake_up_process(rescuer->task); 27973af24433SOleg Nesterov } 27981537663fSTejun Heo 27993af24433SOleg Nesterov /* 2800a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 2801a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 2802a0a1a5fdSTejun Heo * workqueue to workqueues list. 28033af24433SOleg Nesterov */ 28043af24433SOleg Nesterov spin_lock(&workqueue_lock); 2805a0a1a5fdSTejun Heo 2806a0a1a5fdSTejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) 2807f3421797STejun Heo for_each_cwq_cpu(cpu, wq) 2808a0a1a5fdSTejun Heo get_cwq(cpu, wq)->max_active = 0; 2809a0a1a5fdSTejun Heo 28103af24433SOleg Nesterov list_add(&wq->list, &workqueues); 2811a0a1a5fdSTejun Heo 28123af24433SOleg Nesterov spin_unlock(&workqueue_lock); 28133af24433SOleg Nesterov 28143af24433SOleg Nesterov return wq; 28154690c4abSTejun Heo err: 28164690c4abSTejun Heo if (wq) { 2817bdbc5dd7STejun Heo free_cwqs(wq); 2818f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 2819e22bee78STejun Heo kfree(wq->rescuer); 28204690c4abSTejun Heo kfree(wq); 28213af24433SOleg Nesterov } 28224690c4abSTejun Heo return NULL; 28231da177e4SLinus Torvalds } 2824d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 28251da177e4SLinus Torvalds 28263af24433SOleg Nesterov /** 28273af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 28283af24433SOleg Nesterov * @wq: target workqueue 28293af24433SOleg Nesterov * 28303af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 28313af24433SOleg Nesterov */ 28323af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 28333af24433SOleg Nesterov { 2834c8e55f36STejun Heo unsigned int cpu; 28353af24433SOleg Nesterov 2836a0a1a5fdSTejun Heo flush_workqueue(wq); 2837a0a1a5fdSTejun Heo 2838a0a1a5fdSTejun Heo /* 2839a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 2840a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 2841a0a1a5fdSTejun Heo */ 284295402b38SGautham R Shenoy spin_lock(&workqueue_lock); 28433af24433SOleg Nesterov list_del(&wq->list); 284495402b38SGautham R Shenoy spin_unlock(&workqueue_lock); 28453af24433SOleg Nesterov 2846e22bee78STejun Heo /* sanity check */ 2847f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 284873f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 284973f53c4aSTejun Heo int i; 28503af24433SOleg Nesterov 285173f53c4aSTejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 285273f53c4aSTejun Heo BUG_ON(cwq->nr_in_flight[i]); 28531e19ffc6STejun Heo BUG_ON(cwq->nr_active); 28541e19ffc6STejun Heo BUG_ON(!list_empty(&cwq->delayed_works)); 285573f53c4aSTejun Heo } 28561537663fSTejun Heo 2857e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 2858e22bee78STejun Heo kthread_stop(wq->rescuer->task); 2859f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 2860e22bee78STejun Heo } 2861e22bee78STejun Heo 2862bdbc5dd7STejun Heo free_cwqs(wq); 28633af24433SOleg Nesterov kfree(wq); 28643af24433SOleg Nesterov } 28653af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 28663af24433SOleg Nesterov 2867dcd989cbSTejun Heo /** 2868dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 2869dcd989cbSTejun Heo * @wq: target workqueue 2870dcd989cbSTejun Heo * @max_active: new max_active value. 2871dcd989cbSTejun Heo * 2872dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 2873dcd989cbSTejun Heo * 2874dcd989cbSTejun Heo * CONTEXT: 2875dcd989cbSTejun Heo * Don't call from IRQ context. 2876dcd989cbSTejun Heo */ 2877dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 2878dcd989cbSTejun Heo { 2879dcd989cbSTejun Heo unsigned int cpu; 2880dcd989cbSTejun Heo 2881f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 2882dcd989cbSTejun Heo 2883dcd989cbSTejun Heo spin_lock(&workqueue_lock); 2884dcd989cbSTejun Heo 2885dcd989cbSTejun Heo wq->saved_max_active = max_active; 2886dcd989cbSTejun Heo 2887f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 2888dcd989cbSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 2889dcd989cbSTejun Heo 2890dcd989cbSTejun Heo spin_lock_irq(&gcwq->lock); 2891dcd989cbSTejun Heo 2892dcd989cbSTejun Heo if (!(wq->flags & WQ_FREEZEABLE) || 2893dcd989cbSTejun Heo !(gcwq->flags & GCWQ_FREEZING)) 2894dcd989cbSTejun Heo get_cwq(gcwq->cpu, wq)->max_active = max_active; 2895dcd989cbSTejun Heo 2896dcd989cbSTejun Heo spin_unlock_irq(&gcwq->lock); 2897dcd989cbSTejun Heo } 2898dcd989cbSTejun Heo 2899dcd989cbSTejun Heo spin_unlock(&workqueue_lock); 2900dcd989cbSTejun Heo } 2901dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 2902dcd989cbSTejun Heo 2903dcd989cbSTejun Heo /** 2904dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 2905dcd989cbSTejun Heo * @cpu: CPU in question 2906dcd989cbSTejun Heo * @wq: target workqueue 2907dcd989cbSTejun Heo * 2908dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 2909dcd989cbSTejun Heo * no synchronization around this function and the test result is 2910dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 2911dcd989cbSTejun Heo * 2912dcd989cbSTejun Heo * RETURNS: 2913dcd989cbSTejun Heo * %true if congested, %false otherwise. 2914dcd989cbSTejun Heo */ 2915dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 2916dcd989cbSTejun Heo { 2917dcd989cbSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2918dcd989cbSTejun Heo 2919dcd989cbSTejun Heo return !list_empty(&cwq->delayed_works); 2920dcd989cbSTejun Heo } 2921dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 2922dcd989cbSTejun Heo 2923dcd989cbSTejun Heo /** 2924dcd989cbSTejun Heo * work_cpu - return the last known associated cpu for @work 2925dcd989cbSTejun Heo * @work: the work of interest 2926dcd989cbSTejun Heo * 2927dcd989cbSTejun Heo * RETURNS: 2928bdbc5dd7STejun Heo * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. 2929dcd989cbSTejun Heo */ 2930dcd989cbSTejun Heo unsigned int work_cpu(struct work_struct *work) 2931dcd989cbSTejun Heo { 2932dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 2933dcd989cbSTejun Heo 2934bdbc5dd7STejun Heo return gcwq ? gcwq->cpu : WORK_CPU_NONE; 2935dcd989cbSTejun Heo } 2936dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_cpu); 2937dcd989cbSTejun Heo 2938dcd989cbSTejun Heo /** 2939dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 2940dcd989cbSTejun Heo * @work: the work to be tested 2941dcd989cbSTejun Heo * 2942dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 2943dcd989cbSTejun Heo * synchronization around this function and the test result is 2944dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 2945dcd989cbSTejun Heo * Especially for reentrant wqs, the pending state might hide the 2946dcd989cbSTejun Heo * running state. 2947dcd989cbSTejun Heo * 2948dcd989cbSTejun Heo * RETURNS: 2949dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 2950dcd989cbSTejun Heo */ 2951dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 2952dcd989cbSTejun Heo { 2953dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 2954dcd989cbSTejun Heo unsigned long flags; 2955dcd989cbSTejun Heo unsigned int ret = 0; 2956dcd989cbSTejun Heo 2957dcd989cbSTejun Heo if (!gcwq) 2958dcd989cbSTejun Heo return false; 2959dcd989cbSTejun Heo 2960dcd989cbSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 2961dcd989cbSTejun Heo 2962dcd989cbSTejun Heo if (work_pending(work)) 2963dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 2964dcd989cbSTejun Heo if (find_worker_executing_work(gcwq, work)) 2965dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 2966dcd989cbSTejun Heo 2967dcd989cbSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 2968dcd989cbSTejun Heo 2969dcd989cbSTejun Heo return ret; 2970dcd989cbSTejun Heo } 2971dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 2972dcd989cbSTejun Heo 2973db7bccf4STejun Heo /* 2974db7bccf4STejun Heo * CPU hotplug. 2975db7bccf4STejun Heo * 2976e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 2977e22bee78STejun Heo * are a lot of assumptions on strong associations among work, cwq and 2978e22bee78STejun Heo * gcwq which make migrating pending and scheduled works very 2979e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 2980e22bee78STejun Heo * gcwqs serve mix of short, long and very long running works making 2981e22bee78STejun Heo * blocked draining impractical. 2982e22bee78STejun Heo * 2983e22bee78STejun Heo * This is solved by allowing a gcwq to be detached from CPU, running 2984e22bee78STejun Heo * it with unbound (rogue) workers and allowing it to be reattached 2985e22bee78STejun Heo * later if the cpu comes back online. A separate thread is created 2986e22bee78STejun Heo * to govern a gcwq in such state and is called the trustee of the 2987e22bee78STejun Heo * gcwq. 2988db7bccf4STejun Heo * 2989db7bccf4STejun Heo * Trustee states and their descriptions. 2990db7bccf4STejun Heo * 2991db7bccf4STejun Heo * START Command state used on startup. On CPU_DOWN_PREPARE, a 2992db7bccf4STejun Heo * new trustee is started with this state. 2993db7bccf4STejun Heo * 2994db7bccf4STejun Heo * IN_CHARGE Once started, trustee will enter this state after 2995e22bee78STejun Heo * assuming the manager role and making all existing 2996e22bee78STejun Heo * workers rogue. DOWN_PREPARE waits for trustee to 2997e22bee78STejun Heo * enter this state. After reaching IN_CHARGE, trustee 2998e22bee78STejun Heo * tries to execute the pending worklist until it's empty 2999e22bee78STejun Heo * and the state is set to BUTCHER, or the state is set 3000e22bee78STejun Heo * to RELEASE. 3001db7bccf4STejun Heo * 3002db7bccf4STejun Heo * BUTCHER Command state which is set by the cpu callback after 3003db7bccf4STejun Heo * the cpu has went down. Once this state is set trustee 3004db7bccf4STejun Heo * knows that there will be no new works on the worklist 3005db7bccf4STejun Heo * and once the worklist is empty it can proceed to 3006db7bccf4STejun Heo * killing idle workers. 3007db7bccf4STejun Heo * 3008db7bccf4STejun Heo * RELEASE Command state which is set by the cpu callback if the 3009db7bccf4STejun Heo * cpu down has been canceled or it has come online 3010db7bccf4STejun Heo * again. After recognizing this state, trustee stops 3011e22bee78STejun Heo * trying to drain or butcher and clears ROGUE, rebinds 3012e22bee78STejun Heo * all remaining workers back to the cpu and releases 3013e22bee78STejun Heo * manager role. 3014db7bccf4STejun Heo * 3015db7bccf4STejun Heo * DONE Trustee will enter this state after BUTCHER or RELEASE 3016db7bccf4STejun Heo * is complete. 3017db7bccf4STejun Heo * 3018db7bccf4STejun Heo * trustee CPU draining 3019db7bccf4STejun Heo * took over down complete 3020db7bccf4STejun Heo * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE 3021db7bccf4STejun Heo * | | ^ 3022db7bccf4STejun Heo * | CPU is back online v return workers | 3023db7bccf4STejun Heo * ----------------> RELEASE -------------- 3024db7bccf4STejun Heo */ 3025db7bccf4STejun Heo 3026db7bccf4STejun Heo /** 3027db7bccf4STejun Heo * trustee_wait_event_timeout - timed event wait for trustee 3028db7bccf4STejun Heo * @cond: condition to wait for 3029db7bccf4STejun Heo * @timeout: timeout in jiffies 3030db7bccf4STejun Heo * 3031db7bccf4STejun Heo * wait_event_timeout() for trustee to use. Handles locking and 3032db7bccf4STejun Heo * checks for RELEASE request. 3033db7bccf4STejun Heo * 3034db7bccf4STejun Heo * CONTEXT: 3035db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3036db7bccf4STejun Heo * multiple times. To be used by trustee. 3037db7bccf4STejun Heo * 3038db7bccf4STejun Heo * RETURNS: 3039db7bccf4STejun Heo * Positive indicating left time if @cond is satisfied, 0 if timed 3040db7bccf4STejun Heo * out, -1 if canceled. 3041db7bccf4STejun Heo */ 3042db7bccf4STejun Heo #define trustee_wait_event_timeout(cond, timeout) ({ \ 3043db7bccf4STejun Heo long __ret = (timeout); \ 3044db7bccf4STejun Heo while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ 3045db7bccf4STejun Heo __ret) { \ 3046db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); \ 3047db7bccf4STejun Heo __wait_event_timeout(gcwq->trustee_wait, (cond) || \ 3048db7bccf4STejun Heo (gcwq->trustee_state == TRUSTEE_RELEASE), \ 3049db7bccf4STejun Heo __ret); \ 3050db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); \ 3051db7bccf4STejun Heo } \ 3052db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ 3053db7bccf4STejun Heo }) 3054db7bccf4STejun Heo 3055db7bccf4STejun Heo /** 3056db7bccf4STejun Heo * trustee_wait_event - event wait for trustee 3057db7bccf4STejun Heo * @cond: condition to wait for 3058db7bccf4STejun Heo * 3059db7bccf4STejun Heo * wait_event() for trustee to use. Automatically handles locking and 3060db7bccf4STejun Heo * checks for CANCEL request. 3061db7bccf4STejun Heo * 3062db7bccf4STejun Heo * CONTEXT: 3063db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3064db7bccf4STejun Heo * multiple times. To be used by trustee. 3065db7bccf4STejun Heo * 3066db7bccf4STejun Heo * RETURNS: 3067db7bccf4STejun Heo * 0 if @cond is satisfied, -1 if canceled. 3068db7bccf4STejun Heo */ 3069db7bccf4STejun Heo #define trustee_wait_event(cond) ({ \ 3070db7bccf4STejun Heo long __ret1; \ 3071db7bccf4STejun Heo __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ 3072db7bccf4STejun Heo __ret1 < 0 ? -1 : 0; \ 3073db7bccf4STejun Heo }) 3074db7bccf4STejun Heo 3075db7bccf4STejun Heo static int __cpuinit trustee_thread(void *__gcwq) 3076db7bccf4STejun Heo { 3077db7bccf4STejun Heo struct global_cwq *gcwq = __gcwq; 3078db7bccf4STejun Heo struct worker *worker; 3079e22bee78STejun Heo struct work_struct *work; 3080db7bccf4STejun Heo struct hlist_node *pos; 3081e22bee78STejun Heo long rc; 3082db7bccf4STejun Heo int i; 3083db7bccf4STejun Heo 3084db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3085db7bccf4STejun Heo 3086db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3087db7bccf4STejun Heo /* 3088e22bee78STejun Heo * Claim the manager position and make all workers rogue. 3089e22bee78STejun Heo * Trustee must be bound to the target cpu and can't be 3090e22bee78STejun Heo * cancelled. 3091db7bccf4STejun Heo */ 3092db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3093e22bee78STejun Heo rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); 3094e22bee78STejun Heo BUG_ON(rc < 0); 3095e22bee78STejun Heo 3096e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGING_WORKERS; 3097db7bccf4STejun Heo 3098db7bccf4STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) 3099cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3100db7bccf4STejun Heo 3101db7bccf4STejun Heo for_each_busy_worker(worker, i, pos, gcwq) 3102cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3103db7bccf4STejun Heo 3104db7bccf4STejun Heo /* 3105e22bee78STejun Heo * Call schedule() so that we cross rq->lock and thus can 3106e22bee78STejun Heo * guarantee sched callbacks see the rogue flag. This is 3107e22bee78STejun Heo * necessary as scheduler callbacks may be invoked from other 3108e22bee78STejun Heo * cpus. 3109e22bee78STejun Heo */ 3110e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3111e22bee78STejun Heo schedule(); 3112e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3113e22bee78STejun Heo 3114e22bee78STejun Heo /* 3115cb444766STejun Heo * Sched callbacks are disabled now. Zap nr_running. After 3116cb444766STejun Heo * this, nr_running stays zero and need_more_worker() and 3117cb444766STejun Heo * keep_working() are always true as long as the worklist is 3118cb444766STejun Heo * not empty. 3119e22bee78STejun Heo */ 3120cb444766STejun Heo atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); 3121e22bee78STejun Heo 3122e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3123e22bee78STejun Heo del_timer_sync(&gcwq->idle_timer); 3124e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3125e22bee78STejun Heo 3126e22bee78STejun Heo /* 3127db7bccf4STejun Heo * We're now in charge. Notify and proceed to drain. We need 3128db7bccf4STejun Heo * to keep the gcwq running during the whole CPU down 3129db7bccf4STejun Heo * procedure as other cpu hotunplug callbacks may need to 3130db7bccf4STejun Heo * flush currently running tasks. 3131db7bccf4STejun Heo */ 3132db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_IN_CHARGE; 3133db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3134db7bccf4STejun Heo 3135db7bccf4STejun Heo /* 3136db7bccf4STejun Heo * The original cpu is in the process of dying and may go away 3137db7bccf4STejun Heo * anytime now. When that happens, we and all workers would 3138e22bee78STejun Heo * be migrated to other cpus. Try draining any left work. We 3139e22bee78STejun Heo * want to get it over with ASAP - spam rescuers, wake up as 3140e22bee78STejun Heo * many idlers as necessary and create new ones till the 3141e22bee78STejun Heo * worklist is empty. Note that if the gcwq is frozen, there 3142e22bee78STejun Heo * may be frozen works in freezeable cwqs. Don't declare 3143e22bee78STejun Heo * completion while frozen. 3144db7bccf4STejun Heo */ 3145db7bccf4STejun Heo while (gcwq->nr_workers != gcwq->nr_idle || 3146db7bccf4STejun Heo gcwq->flags & GCWQ_FREEZING || 3147db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_IN_CHARGE) { 3148e22bee78STejun Heo int nr_works = 0; 3149e22bee78STejun Heo 3150e22bee78STejun Heo list_for_each_entry(work, &gcwq->worklist, entry) { 3151e22bee78STejun Heo send_mayday(work); 3152e22bee78STejun Heo nr_works++; 3153e22bee78STejun Heo } 3154e22bee78STejun Heo 3155e22bee78STejun Heo list_for_each_entry(worker, &gcwq->idle_list, entry) { 3156e22bee78STejun Heo if (!nr_works--) 3157e22bee78STejun Heo break; 3158e22bee78STejun Heo wake_up_process(worker->task); 3159e22bee78STejun Heo } 3160e22bee78STejun Heo 3161e22bee78STejun Heo if (need_to_create_worker(gcwq)) { 3162e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3163e22bee78STejun Heo worker = create_worker(gcwq, false); 3164e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3165e22bee78STejun Heo if (worker) { 3166cb444766STejun Heo worker->flags |= WORKER_ROGUE; 3167e22bee78STejun Heo start_worker(worker); 3168e22bee78STejun Heo } 3169e22bee78STejun Heo } 3170e22bee78STejun Heo 3171db7bccf4STejun Heo /* give a breather */ 3172db7bccf4STejun Heo if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) 3173db7bccf4STejun Heo break; 3174db7bccf4STejun Heo } 3175db7bccf4STejun Heo 3176e22bee78STejun Heo /* 3177e22bee78STejun Heo * Either all works have been scheduled and cpu is down, or 3178e22bee78STejun Heo * cpu down has already been canceled. Wait for and butcher 3179e22bee78STejun Heo * all workers till we're canceled. 3180e22bee78STejun Heo */ 3181e22bee78STejun Heo do { 3182e22bee78STejun Heo rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); 3183e22bee78STejun Heo while (!list_empty(&gcwq->idle_list)) 3184e22bee78STejun Heo destroy_worker(list_first_entry(&gcwq->idle_list, 3185e22bee78STejun Heo struct worker, entry)); 3186e22bee78STejun Heo } while (gcwq->nr_workers && rc >= 0); 3187e22bee78STejun Heo 3188e22bee78STejun Heo /* 3189e22bee78STejun Heo * At this point, either draining has completed and no worker 3190e22bee78STejun Heo * is left, or cpu down has been canceled or the cpu is being 3191e22bee78STejun Heo * brought back up. There shouldn't be any idle one left. 3192e22bee78STejun Heo * Tell the remaining busy ones to rebind once it finishes the 3193e22bee78STejun Heo * currently scheduled works by scheduling the rebind_work. 3194e22bee78STejun Heo */ 3195e22bee78STejun Heo WARN_ON(!list_empty(&gcwq->idle_list)); 3196e22bee78STejun Heo 3197e22bee78STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 3198e22bee78STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 3199e22bee78STejun Heo 3200e22bee78STejun Heo /* 3201e22bee78STejun Heo * Rebind_work may race with future cpu hotplug 3202e22bee78STejun Heo * operations. Use a separate flag to mark that 3203e22bee78STejun Heo * rebinding is scheduled. 3204e22bee78STejun Heo */ 3205cb444766STejun Heo worker->flags |= WORKER_REBIND; 3206cb444766STejun Heo worker->flags &= ~WORKER_ROGUE; 3207e22bee78STejun Heo 3208e22bee78STejun Heo /* queue rebind_work, wq doesn't matter, use the default one */ 3209e22bee78STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 3210e22bee78STejun Heo work_data_bits(rebind_work))) 3211e22bee78STejun Heo continue; 3212e22bee78STejun Heo 3213e22bee78STejun Heo debug_work_activate(rebind_work); 3214d320c038STejun Heo insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, 3215e22bee78STejun Heo worker->scheduled.next, 3216e22bee78STejun Heo work_color_to_flags(WORK_NO_COLOR)); 3217e22bee78STejun Heo } 3218e22bee78STejun Heo 3219e22bee78STejun Heo /* relinquish manager role */ 3220e22bee78STejun Heo gcwq->flags &= ~GCWQ_MANAGING_WORKERS; 3221e22bee78STejun Heo 3222db7bccf4STejun Heo /* notify completion */ 3223db7bccf4STejun Heo gcwq->trustee = NULL; 3224db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3225db7bccf4STejun Heo wake_up_all(&gcwq->trustee_wait); 3226db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3227db7bccf4STejun Heo return 0; 3228db7bccf4STejun Heo } 3229db7bccf4STejun Heo 3230db7bccf4STejun Heo /** 3231db7bccf4STejun Heo * wait_trustee_state - wait for trustee to enter the specified state 3232db7bccf4STejun Heo * @gcwq: gcwq the trustee of interest belongs to 3233db7bccf4STejun Heo * @state: target state to wait for 3234db7bccf4STejun Heo * 3235db7bccf4STejun Heo * Wait for the trustee to reach @state. DONE is already matched. 3236db7bccf4STejun Heo * 3237db7bccf4STejun Heo * CONTEXT: 3238db7bccf4STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 3239db7bccf4STejun Heo * multiple times. To be used by cpu_callback. 3240db7bccf4STejun Heo */ 3241db7bccf4STejun Heo static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) 3242db7bccf4STejun Heo { 3243db7bccf4STejun Heo if (!(gcwq->trustee_state == state || 3244db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE)) { 3245db7bccf4STejun Heo spin_unlock_irq(&gcwq->lock); 3246db7bccf4STejun Heo __wait_event(gcwq->trustee_wait, 3247db7bccf4STejun Heo gcwq->trustee_state == state || 3248db7bccf4STejun Heo gcwq->trustee_state == TRUSTEE_DONE); 3249db7bccf4STejun Heo spin_lock_irq(&gcwq->lock); 3250db7bccf4STejun Heo } 3251db7bccf4STejun Heo } 3252db7bccf4STejun Heo 32539c7b216dSChandra Seetharaman static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 32541da177e4SLinus Torvalds unsigned long action, 32551da177e4SLinus Torvalds void *hcpu) 32561da177e4SLinus Torvalds { 32573af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 3258db7bccf4STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3259db7bccf4STejun Heo struct task_struct *new_trustee = NULL; 3260e22bee78STejun Heo struct worker *uninitialized_var(new_worker); 3261db7bccf4STejun Heo unsigned long flags; 32621da177e4SLinus Torvalds 32638bb78442SRafael J. Wysocki action &= ~CPU_TASKS_FROZEN; 32648bb78442SRafael J. Wysocki 32651da177e4SLinus Torvalds switch (action) { 3266db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3267db7bccf4STejun Heo new_trustee = kthread_create(trustee_thread, gcwq, 3268db7bccf4STejun Heo "workqueue_trustee/%d\n", cpu); 3269db7bccf4STejun Heo if (IS_ERR(new_trustee)) 3270db7bccf4STejun Heo return notifier_from_errno(PTR_ERR(new_trustee)); 3271db7bccf4STejun Heo kthread_bind(new_trustee, cpu); 3272e22bee78STejun Heo /* fall through */ 32733af24433SOleg Nesterov case CPU_UP_PREPARE: 3274e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3275e22bee78STejun Heo new_worker = create_worker(gcwq, false); 3276e22bee78STejun Heo if (!new_worker) { 3277e22bee78STejun Heo if (new_trustee) 3278e22bee78STejun Heo kthread_stop(new_trustee); 3279e22bee78STejun Heo return NOTIFY_BAD; 32803af24433SOleg Nesterov } 3281db7bccf4STejun Heo } 32821537663fSTejun Heo 3283db7bccf4STejun Heo /* some are called w/ irq disabled, don't disturb irq status */ 3284db7bccf4STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 32853af24433SOleg Nesterov 32863af24433SOleg Nesterov switch (action) { 3287db7bccf4STejun Heo case CPU_DOWN_PREPARE: 3288db7bccf4STejun Heo /* initialize trustee and tell it to acquire the gcwq */ 3289db7bccf4STejun Heo BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); 3290db7bccf4STejun Heo gcwq->trustee = new_trustee; 3291db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_START; 3292db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3293db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); 3294e22bee78STejun Heo /* fall through */ 32953af24433SOleg Nesterov case CPU_UP_PREPARE: 3296e22bee78STejun Heo BUG_ON(gcwq->first_idle); 3297e22bee78STejun Heo gcwq->first_idle = new_worker; 32981da177e4SLinus Torvalds break; 32991da177e4SLinus Torvalds 3300e22bee78STejun Heo case CPU_DYING: 3301e22bee78STejun Heo /* 3302e22bee78STejun Heo * Before this, the trustee and all workers except for 3303e22bee78STejun Heo * the ones which are still executing works from 3304e22bee78STejun Heo * before the last CPU down must be on the cpu. After 3305e22bee78STejun Heo * this, they'll all be diasporas. 3306e22bee78STejun Heo */ 3307e22bee78STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 3308db7bccf4STejun Heo break; 3309db7bccf4STejun Heo 33103da1c84cSOleg Nesterov case CPU_POST_DEAD: 3311db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_BUTCHER; 3312e22bee78STejun Heo /* fall through */ 3313e22bee78STejun Heo case CPU_UP_CANCELED: 3314e22bee78STejun Heo destroy_worker(gcwq->first_idle); 3315e22bee78STejun Heo gcwq->first_idle = NULL; 3316db7bccf4STejun Heo break; 3317db7bccf4STejun Heo 3318db7bccf4STejun Heo case CPU_DOWN_FAILED: 33191da177e4SLinus Torvalds case CPU_ONLINE: 3320e22bee78STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 3321db7bccf4STejun Heo if (gcwq->trustee_state != TRUSTEE_DONE) { 3322db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_RELEASE; 3323db7bccf4STejun Heo wake_up_process(gcwq->trustee); 3324db7bccf4STejun Heo wait_trustee_state(gcwq, TRUSTEE_DONE); 3325db7bccf4STejun Heo } 33261da177e4SLinus Torvalds 3327e22bee78STejun Heo /* 3328e22bee78STejun Heo * Trustee is done and there might be no worker left. 3329e22bee78STejun Heo * Put the first_idle in and request a real manager to 3330e22bee78STejun Heo * take a look. 3331e22bee78STejun Heo */ 3332e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3333e22bee78STejun Heo kthread_bind(gcwq->first_idle->task, cpu); 3334e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3335e22bee78STejun Heo gcwq->flags |= GCWQ_MANAGE_WORKERS; 3336e22bee78STejun Heo start_worker(gcwq->first_idle); 3337e22bee78STejun Heo gcwq->first_idle = NULL; 33381da177e4SLinus Torvalds break; 33391da177e4SLinus Torvalds } 33401da177e4SLinus Torvalds 3341db7bccf4STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 334200dfcaf7SOleg Nesterov 33431537663fSTejun Heo return notifier_from_errno(0); 33441da177e4SLinus Torvalds } 33451da177e4SLinus Torvalds 33462d3854a3SRusty Russell #ifdef CONFIG_SMP 33478ccad40dSRusty Russell 33482d3854a3SRusty Russell struct work_for_cpu { 33496b44003eSAndrew Morton struct completion completion; 33502d3854a3SRusty Russell long (*fn)(void *); 33512d3854a3SRusty Russell void *arg; 33522d3854a3SRusty Russell long ret; 33532d3854a3SRusty Russell }; 33542d3854a3SRusty Russell 33556b44003eSAndrew Morton static int do_work_for_cpu(void *_wfc) 33562d3854a3SRusty Russell { 33576b44003eSAndrew Morton struct work_for_cpu *wfc = _wfc; 33582d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 33596b44003eSAndrew Morton complete(&wfc->completion); 33606b44003eSAndrew Morton return 0; 33612d3854a3SRusty Russell } 33622d3854a3SRusty Russell 33632d3854a3SRusty Russell /** 33642d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 33652d3854a3SRusty Russell * @cpu: the cpu to run on 33662d3854a3SRusty Russell * @fn: the function to run 33672d3854a3SRusty Russell * @arg: the function arg 33682d3854a3SRusty Russell * 336931ad9081SRusty Russell * This will return the value @fn returns. 337031ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 33716b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 33722d3854a3SRusty Russell */ 33732d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 33742d3854a3SRusty Russell { 33756b44003eSAndrew Morton struct task_struct *sub_thread; 33766b44003eSAndrew Morton struct work_for_cpu wfc = { 33776b44003eSAndrew Morton .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), 33786b44003eSAndrew Morton .fn = fn, 33796b44003eSAndrew Morton .arg = arg, 33806b44003eSAndrew Morton }; 33812d3854a3SRusty Russell 33826b44003eSAndrew Morton sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); 33836b44003eSAndrew Morton if (IS_ERR(sub_thread)) 33846b44003eSAndrew Morton return PTR_ERR(sub_thread); 33856b44003eSAndrew Morton kthread_bind(sub_thread, cpu); 33866b44003eSAndrew Morton wake_up_process(sub_thread); 33876b44003eSAndrew Morton wait_for_completion(&wfc.completion); 33882d3854a3SRusty Russell return wfc.ret; 33892d3854a3SRusty Russell } 33902d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 33912d3854a3SRusty Russell #endif /* CONFIG_SMP */ 33922d3854a3SRusty Russell 3393a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3394e7577c50SRusty Russell 3395a0a1a5fdSTejun Heo /** 3396a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3397a0a1a5fdSTejun Heo * 3398a0a1a5fdSTejun Heo * Start freezing workqueues. After this function returns, all 3399a0a1a5fdSTejun Heo * freezeable workqueues will queue new works to their frozen_works 34007e11629dSTejun Heo * list instead of gcwq->worklist. 3401a0a1a5fdSTejun Heo * 3402a0a1a5fdSTejun Heo * CONTEXT: 34038b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3404a0a1a5fdSTejun Heo */ 3405a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3406a0a1a5fdSTejun Heo { 3407a0a1a5fdSTejun Heo unsigned int cpu; 3408a0a1a5fdSTejun Heo 3409a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3410a0a1a5fdSTejun Heo 3411a0a1a5fdSTejun Heo BUG_ON(workqueue_freezing); 3412a0a1a5fdSTejun Heo workqueue_freezing = true; 3413a0a1a5fdSTejun Heo 3414f3421797STejun Heo for_each_gcwq_cpu(cpu) { 34158b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3416bdbc5dd7STejun Heo struct workqueue_struct *wq; 34178b03ae3cSTejun Heo 34188b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 34198b03ae3cSTejun Heo 3420db7bccf4STejun Heo BUG_ON(gcwq->flags & GCWQ_FREEZING); 3421db7bccf4STejun Heo gcwq->flags |= GCWQ_FREEZING; 3422db7bccf4STejun Heo 3423a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3424a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3425a0a1a5fdSTejun Heo 3426f3421797STejun Heo if (cwq && wq->flags & WQ_FREEZEABLE) 3427a0a1a5fdSTejun Heo cwq->max_active = 0; 34281da177e4SLinus Torvalds } 34298b03ae3cSTejun Heo 34308b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3431a0a1a5fdSTejun Heo } 3432a0a1a5fdSTejun Heo 3433a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3434a0a1a5fdSTejun Heo } 3435a0a1a5fdSTejun Heo 3436a0a1a5fdSTejun Heo /** 3437a0a1a5fdSTejun Heo * freeze_workqueues_busy - are freezeable workqueues still busy? 3438a0a1a5fdSTejun Heo * 3439a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3440a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3441a0a1a5fdSTejun Heo * 3442a0a1a5fdSTejun Heo * CONTEXT: 3443a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3444a0a1a5fdSTejun Heo * 3445a0a1a5fdSTejun Heo * RETURNS: 3446a0a1a5fdSTejun Heo * %true if some freezeable workqueues are still busy. %false if 3447a0a1a5fdSTejun Heo * freezing is complete. 3448a0a1a5fdSTejun Heo */ 3449a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3450a0a1a5fdSTejun Heo { 3451a0a1a5fdSTejun Heo unsigned int cpu; 3452a0a1a5fdSTejun Heo bool busy = false; 3453a0a1a5fdSTejun Heo 3454a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3455a0a1a5fdSTejun Heo 3456a0a1a5fdSTejun Heo BUG_ON(!workqueue_freezing); 3457a0a1a5fdSTejun Heo 3458f3421797STejun Heo for_each_gcwq_cpu(cpu) { 3459bdbc5dd7STejun Heo struct workqueue_struct *wq; 3460a0a1a5fdSTejun Heo /* 3461a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3462a0a1a5fdSTejun Heo * to peek without lock. 3463a0a1a5fdSTejun Heo */ 3464a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3465a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3466a0a1a5fdSTejun Heo 3467f3421797STejun Heo if (!cwq || !(wq->flags & WQ_FREEZEABLE)) 3468a0a1a5fdSTejun Heo continue; 3469a0a1a5fdSTejun Heo 3470a0a1a5fdSTejun Heo BUG_ON(cwq->nr_active < 0); 3471a0a1a5fdSTejun Heo if (cwq->nr_active) { 3472a0a1a5fdSTejun Heo busy = true; 3473a0a1a5fdSTejun Heo goto out_unlock; 3474a0a1a5fdSTejun Heo } 3475a0a1a5fdSTejun Heo } 3476a0a1a5fdSTejun Heo } 3477a0a1a5fdSTejun Heo out_unlock: 3478a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3479a0a1a5fdSTejun Heo return busy; 3480a0a1a5fdSTejun Heo } 3481a0a1a5fdSTejun Heo 3482a0a1a5fdSTejun Heo /** 3483a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3484a0a1a5fdSTejun Heo * 3485a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 34867e11629dSTejun Heo * frozen works are transferred to their respective gcwq worklists. 3487a0a1a5fdSTejun Heo * 3488a0a1a5fdSTejun Heo * CONTEXT: 34898b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3490a0a1a5fdSTejun Heo */ 3491a0a1a5fdSTejun Heo void thaw_workqueues(void) 3492a0a1a5fdSTejun Heo { 3493a0a1a5fdSTejun Heo unsigned int cpu; 3494a0a1a5fdSTejun Heo 3495a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3496a0a1a5fdSTejun Heo 3497a0a1a5fdSTejun Heo if (!workqueue_freezing) 3498a0a1a5fdSTejun Heo goto out_unlock; 3499a0a1a5fdSTejun Heo 3500f3421797STejun Heo for_each_gcwq_cpu(cpu) { 35018b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3502bdbc5dd7STejun Heo struct workqueue_struct *wq; 35038b03ae3cSTejun Heo 35048b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 35058b03ae3cSTejun Heo 3506db7bccf4STejun Heo BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); 3507db7bccf4STejun Heo gcwq->flags &= ~GCWQ_FREEZING; 3508db7bccf4STejun Heo 3509a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3510a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3511a0a1a5fdSTejun Heo 3512f3421797STejun Heo if (!cwq || !(wq->flags & WQ_FREEZEABLE)) 3513a0a1a5fdSTejun Heo continue; 3514a0a1a5fdSTejun Heo 3515a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 3516a0a1a5fdSTejun Heo cwq->max_active = wq->saved_max_active; 3517a0a1a5fdSTejun Heo 3518a0a1a5fdSTejun Heo while (!list_empty(&cwq->delayed_works) && 3519a0a1a5fdSTejun Heo cwq->nr_active < cwq->max_active) 3520a0a1a5fdSTejun Heo cwq_activate_first_delayed(cwq); 3521a0a1a5fdSTejun Heo } 35228b03ae3cSTejun Heo 3523e22bee78STejun Heo wake_up_worker(gcwq); 3524e22bee78STejun Heo 35258b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3526a0a1a5fdSTejun Heo } 3527a0a1a5fdSTejun Heo 3528a0a1a5fdSTejun Heo workqueue_freezing = false; 3529a0a1a5fdSTejun Heo out_unlock: 3530a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3531a0a1a5fdSTejun Heo } 3532a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3533a0a1a5fdSTejun Heo 35346ee0578bSSuresh Siddha static int __init init_workqueues(void) 35351da177e4SLinus Torvalds { 3536c34056a3STejun Heo unsigned int cpu; 3537c8e55f36STejun Heo int i; 3538c34056a3STejun Heo 3539f6500947STejun Heo cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); 35408b03ae3cSTejun Heo 35418b03ae3cSTejun Heo /* initialize gcwqs */ 3542f3421797STejun Heo for_each_gcwq_cpu(cpu) { 35438b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 35448b03ae3cSTejun Heo 35458b03ae3cSTejun Heo spin_lock_init(&gcwq->lock); 35467e11629dSTejun Heo INIT_LIST_HEAD(&gcwq->worklist); 35478b03ae3cSTejun Heo gcwq->cpu = cpu; 3548f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 3549f3421797STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 35508b03ae3cSTejun Heo 3551c8e55f36STejun Heo INIT_LIST_HEAD(&gcwq->idle_list); 3552c8e55f36STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) 3553c8e55f36STejun Heo INIT_HLIST_HEAD(&gcwq->busy_hash[i]); 3554c8e55f36STejun Heo 3555e22bee78STejun Heo init_timer_deferrable(&gcwq->idle_timer); 3556e22bee78STejun Heo gcwq->idle_timer.function = idle_worker_timeout; 3557e22bee78STejun Heo gcwq->idle_timer.data = (unsigned long)gcwq; 3558e22bee78STejun Heo 3559e22bee78STejun Heo setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, 3560e22bee78STejun Heo (unsigned long)gcwq); 3561e22bee78STejun Heo 35628b03ae3cSTejun Heo ida_init(&gcwq->worker_ida); 3563db7bccf4STejun Heo 3564db7bccf4STejun Heo gcwq->trustee_state = TRUSTEE_DONE; 3565db7bccf4STejun Heo init_waitqueue_head(&gcwq->trustee_wait); 35668b03ae3cSTejun Heo } 35678b03ae3cSTejun Heo 3568e22bee78STejun Heo /* create the initial worker */ 3569f3421797STejun Heo for_each_online_gcwq_cpu(cpu) { 3570e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3571e22bee78STejun Heo struct worker *worker; 3572e22bee78STejun Heo 3573e22bee78STejun Heo worker = create_worker(gcwq, true); 3574e22bee78STejun Heo BUG_ON(!worker); 3575e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3576e22bee78STejun Heo start_worker(worker); 3577e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3578e22bee78STejun Heo } 3579e22bee78STejun Heo 3580d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 3581d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3582d320c038STejun Heo system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); 3583f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3584f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 3585d320c038STejun Heo BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq); 35866ee0578bSSuresh Siddha return 0; 35871da177e4SLinus Torvalds } 35886ee0578bSSuresh Siddha early_initcall(init_workqueues); 3589