11da177e4SLinus Torvalds /* 2c54fce6eSTejun Heo * kernel/workqueue.c - generic async execution with shared worker pool 31da177e4SLinus Torvalds * 4c54fce6eSTejun Heo * Copyright (C) 2002 Ingo Molnar 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Derived from the taskqueue/keventd code by: 71da177e4SLinus Torvalds * David Woodhouse <dwmw2@infradead.org> 8e1f8e874SFrancois Cami * Andrew Morton 91da177e4SLinus Torvalds * Kai Petzke <wpp@marie.physik.tu-berlin.de> 101da177e4SLinus Torvalds * Theodore Ts'o <tytso@mit.edu> 1189ada679SChristoph Lameter * 12cde53535SChristoph Lameter * Made to use alloc_percpu by Christoph Lameter. 13c54fce6eSTejun Heo * 14c54fce6eSTejun Heo * Copyright (C) 2010 SUSE Linux Products GmbH 15c54fce6eSTejun Heo * Copyright (C) 2010 Tejun Heo <tj@kernel.org> 16c54fce6eSTejun Heo * 17c54fce6eSTejun Heo * This is the generic async execution mechanism. Work items as are 18c54fce6eSTejun Heo * executed in process context. The worker pool is shared and 19c54fce6eSTejun Heo * automatically managed. There is one worker pool for each CPU and 20c54fce6eSTejun Heo * one extra for works which are better served by workers which are 21c54fce6eSTejun Heo * not bound to any specific CPU. 22c54fce6eSTejun Heo * 23c54fce6eSTejun Heo * Please read Documentation/workqueue.txt for details. 241da177e4SLinus Torvalds */ 251da177e4SLinus Torvalds 269984de1aSPaul Gortmaker #include <linux/export.h> 271da177e4SLinus Torvalds #include <linux/kernel.h> 281da177e4SLinus Torvalds #include <linux/sched.h> 291da177e4SLinus Torvalds #include <linux/init.h> 301da177e4SLinus Torvalds #include <linux/signal.h> 311da177e4SLinus Torvalds #include <linux/completion.h> 321da177e4SLinus Torvalds #include <linux/workqueue.h> 331da177e4SLinus Torvalds #include <linux/slab.h> 341da177e4SLinus Torvalds #include <linux/cpu.h> 351da177e4SLinus Torvalds #include <linux/notifier.h> 361da177e4SLinus Torvalds #include <linux/kthread.h> 371fa44ecaSJames Bottomley #include <linux/hardirq.h> 3846934023SChristoph Lameter #include <linux/mempolicy.h> 39341a5958SRafael J. Wysocki #include <linux/freezer.h> 40d5abe669SPeter Zijlstra #include <linux/kallsyms.h> 41d5abe669SPeter Zijlstra #include <linux/debug_locks.h> 424e6045f1SJohannes Berg #include <linux/lockdep.h> 43c34056a3STejun Heo #include <linux/idr.h> 44e22bee78STejun Heo 45e22bee78STejun Heo #include "workqueue_sched.h" 461da177e4SLinus Torvalds 47c8e55f36STejun Heo enum { 48bc2ae0f5STejun Heo /* 49bc2ae0f5STejun Heo * global_cwq flags 50bc2ae0f5STejun Heo * 51bc2ae0f5STejun Heo * A bound gcwq is either associated or disassociated with its CPU. 52bc2ae0f5STejun Heo * While associated (!DISASSOCIATED), all workers are bound to the 53bc2ae0f5STejun Heo * CPU and none has %WORKER_UNBOUND set and concurrency management 54bc2ae0f5STejun Heo * is in effect. 55bc2ae0f5STejun Heo * 56bc2ae0f5STejun Heo * While DISASSOCIATED, the cpu may be offline and all workers have 57bc2ae0f5STejun Heo * %WORKER_UNBOUND set and concurrency management disabled, and may 58bc2ae0f5STejun Heo * be executing on any CPU. The gcwq behaves as an unbound one. 59bc2ae0f5STejun Heo * 60bc2ae0f5STejun Heo * Note that DISASSOCIATED can be flipped only while holding 61bc2ae0f5STejun Heo * managership of all pools on the gcwq to avoid changing binding 62bc2ae0f5STejun Heo * state while create_worker() is in progress. 63bc2ae0f5STejun Heo */ 6411ebea50STejun Heo GCWQ_DISASSOCIATED = 1 << 0, /* cpu can't serve workers */ 6511ebea50STejun Heo GCWQ_FREEZING = 1 << 1, /* freeze in progress */ 6611ebea50STejun Heo 6711ebea50STejun Heo /* pool flags */ 6811ebea50STejun Heo POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ 69db7bccf4STejun Heo 70c8e55f36STejun Heo /* worker flags */ 71c8e55f36STejun Heo WORKER_STARTED = 1 << 0, /* started */ 72c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 73c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 74e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 75e22bee78STejun Heo WORKER_REBIND = 1 << 5, /* mom is home, come back */ 76fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 77f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 78e22bee78STejun Heo 79403c821dSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_REBIND | WORKER_UNBOUND | 80403c821dSTejun Heo WORKER_CPU_INTENSIVE, 81db7bccf4STejun Heo 823270476aSTejun Heo NR_WORKER_POOLS = 2, /* # worker pools per gcwq */ 834ce62e9eSTejun Heo 84c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 85c8e55f36STejun Heo BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, 86c8e55f36STejun Heo BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, 87db7bccf4STejun Heo 88e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 89e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 90e22bee78STejun Heo 913233cdbdSTejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, 923233cdbdSTejun Heo /* call for help after 10ms 933233cdbdSTejun Heo (min two ticks) */ 94e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 95e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 961da177e4SLinus Torvalds 971da177e4SLinus Torvalds /* 98e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 99e22bee78STejun Heo * all cpus. Give -20. 100e22bee78STejun Heo */ 101e22bee78STejun Heo RESCUER_NICE_LEVEL = -20, 1023270476aSTejun Heo HIGHPRI_NICE_LEVEL = -20, 103c8e55f36STejun Heo }; 104c8e55f36STejun Heo 1051da177e4SLinus Torvalds /* 1064690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 1074690c4abSTejun Heo * 108e41e704bSTejun Heo * I: Modifiable by initialization/destruction paths and read-only for 109e41e704bSTejun Heo * everyone else. 1104690c4abSTejun Heo * 111e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 112e22bee78STejun Heo * only be modified and accessed from the local cpu. 113e22bee78STejun Heo * 1148b03ae3cSTejun Heo * L: gcwq->lock protected. Access with gcwq->lock held. 1154690c4abSTejun Heo * 116e22bee78STejun Heo * X: During normal operation, modification requires gcwq->lock and 117e22bee78STejun Heo * should be done only from local cpu. Either disabling preemption 118e22bee78STejun Heo * on local cpu or grabbing gcwq->lock is enough for read access. 119f3421797STejun Heo * If GCWQ_DISASSOCIATED is set, it's identical to L. 120e22bee78STejun Heo * 12173f53c4aSTejun Heo * F: wq->flush_mutex protected. 12273f53c4aSTejun Heo * 1234690c4abSTejun Heo * W: workqueue_lock protected. 1244690c4abSTejun Heo */ 1254690c4abSTejun Heo 1268b03ae3cSTejun Heo struct global_cwq; 127bd7bdd43STejun Heo struct worker_pool; 12825511a47STejun Heo struct idle_rebind; 129c34056a3STejun Heo 130e22bee78STejun Heo /* 131e22bee78STejun Heo * The poor guys doing the actual heavy lifting. All on-duty workers 132e22bee78STejun Heo * are either serving the manager role, on idle list or on busy hash. 133e22bee78STejun Heo */ 134c34056a3STejun Heo struct worker { 135c8e55f36STejun Heo /* on idle list while idle, on busy hash table while busy */ 136c8e55f36STejun Heo union { 137c8e55f36STejun Heo struct list_head entry; /* L: while idle */ 138c8e55f36STejun Heo struct hlist_node hentry; /* L: while busy */ 139c8e55f36STejun Heo }; 140c8e55f36STejun Heo 141c34056a3STejun Heo struct work_struct *current_work; /* L: work being processed */ 1428cca0eeaSTejun Heo struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ 143affee4b2STejun Heo struct list_head scheduled; /* L: scheduled works */ 144c34056a3STejun Heo struct task_struct *task; /* I: worker task */ 145bd7bdd43STejun Heo struct worker_pool *pool; /* I: the associated pool */ 146e22bee78STejun Heo /* 64 bytes boundary on 64bit, 32 on 32bit */ 147e22bee78STejun Heo unsigned long last_active; /* L: last active timestamp */ 148e22bee78STejun Heo unsigned int flags; /* X: flags */ 149c34056a3STejun Heo int id; /* I: worker id */ 15025511a47STejun Heo 15125511a47STejun Heo /* for rebinding worker to CPU */ 15225511a47STejun Heo struct idle_rebind *idle_rebind; /* L: for idle worker */ 15325511a47STejun Heo struct work_struct rebind_work; /* L: for busy worker */ 154c34056a3STejun Heo }; 155c34056a3STejun Heo 156bd7bdd43STejun Heo struct worker_pool { 157bd7bdd43STejun Heo struct global_cwq *gcwq; /* I: the owning gcwq */ 15811ebea50STejun Heo unsigned int flags; /* X: flags */ 159bd7bdd43STejun Heo 160bd7bdd43STejun Heo struct list_head worklist; /* L: list of pending works */ 161bd7bdd43STejun Heo int nr_workers; /* L: total number of workers */ 162bd7bdd43STejun Heo int nr_idle; /* L: currently idle ones */ 163bd7bdd43STejun Heo 164bd7bdd43STejun Heo struct list_head idle_list; /* X: list of idle workers */ 165bd7bdd43STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 166bd7bdd43STejun Heo struct timer_list mayday_timer; /* L: SOS timer for workers */ 167bd7bdd43STejun Heo 16860373152STejun Heo struct mutex manager_mutex; /* mutex manager should hold */ 169bd7bdd43STejun Heo struct ida worker_ida; /* L: for worker IDs */ 170bd7bdd43STejun Heo }; 171bd7bdd43STejun Heo 1724690c4abSTejun Heo /* 173e22bee78STejun Heo * Global per-cpu workqueue. There's one and only one for each cpu 174e22bee78STejun Heo * and all works are queued and processed here regardless of their 175e22bee78STejun Heo * target workqueues. 1768b03ae3cSTejun Heo */ 1778b03ae3cSTejun Heo struct global_cwq { 1788b03ae3cSTejun Heo spinlock_t lock; /* the gcwq lock */ 1798b03ae3cSTejun Heo unsigned int cpu; /* I: the associated cpu */ 180db7bccf4STejun Heo unsigned int flags; /* L: GCWQ_* flags */ 181c8e55f36STejun Heo 182bd7bdd43STejun Heo /* workers are chained either in busy_hash or pool idle_list */ 183c8e55f36STejun Heo struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; 184c8e55f36STejun Heo /* L: hash of busy workers */ 185c8e55f36STejun Heo 186330dad5bSJoonsoo Kim struct worker_pool pools[NR_WORKER_POOLS]; 187330dad5bSJoonsoo Kim /* normal and highpri pools */ 188db7bccf4STejun Heo 18925511a47STejun Heo wait_queue_head_t rebind_hold; /* rebind hold wait */ 1908b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1918b03ae3cSTejun Heo 1928b03ae3cSTejun Heo /* 193502ca9d8STejun Heo * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of 1940f900049STejun Heo * work_struct->data are used for flags and thus cwqs need to be 1950f900049STejun Heo * aligned at two's power of the number of flag bits. 1961da177e4SLinus Torvalds */ 1971da177e4SLinus Torvalds struct cpu_workqueue_struct { 198bd7bdd43STejun Heo struct worker_pool *pool; /* I: the associated pool */ 1994690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 20073f53c4aSTejun Heo int work_color; /* L: current color */ 20173f53c4aSTejun Heo int flush_color; /* L: flushing color */ 20273f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 20373f53c4aSTejun Heo /* L: nr of in_flight works */ 2041e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 205a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 2061e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 2070f900049STejun Heo }; 2081da177e4SLinus Torvalds 2091da177e4SLinus Torvalds /* 21073f53c4aSTejun Heo * Structure used to wait for workqueue flush. 21173f53c4aSTejun Heo */ 21273f53c4aSTejun Heo struct wq_flusher { 21373f53c4aSTejun Heo struct list_head list; /* F: list of flushers */ 21473f53c4aSTejun Heo int flush_color; /* F: flush color waiting for */ 21573f53c4aSTejun Heo struct completion done; /* flush completion */ 21673f53c4aSTejun Heo }; 2171da177e4SLinus Torvalds 21873f53c4aSTejun Heo /* 219f2e005aaSTejun Heo * All cpumasks are assumed to be always set on UP and thus can't be 220f2e005aaSTejun Heo * used to determine whether there's something to be done. 221f2e005aaSTejun Heo */ 222f2e005aaSTejun Heo #ifdef CONFIG_SMP 223f2e005aaSTejun Heo typedef cpumask_var_t mayday_mask_t; 224f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) \ 225f2e005aaSTejun Heo cpumask_test_and_set_cpu((cpu), (mask)) 226f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) 227f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) 2289c37547aSTejun Heo #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) 229f2e005aaSTejun Heo #define free_mayday_mask(mask) free_cpumask_var((mask)) 230f2e005aaSTejun Heo #else 231f2e005aaSTejun Heo typedef unsigned long mayday_mask_t; 232f2e005aaSTejun Heo #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) 233f2e005aaSTejun Heo #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) 234f2e005aaSTejun Heo #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) 235f2e005aaSTejun Heo #define alloc_mayday_mask(maskp, gfp) true 236f2e005aaSTejun Heo #define free_mayday_mask(mask) do { } while (0) 237f2e005aaSTejun Heo #endif 2381da177e4SLinus Torvalds 2391da177e4SLinus Torvalds /* 2401da177e4SLinus Torvalds * The externally visible workqueue abstraction is an array of 2411da177e4SLinus Torvalds * per-CPU workqueues: 2421da177e4SLinus Torvalds */ 2431da177e4SLinus Torvalds struct workqueue_struct { 2449c5a2ba7STejun Heo unsigned int flags; /* W: WQ_* flags */ 245bdbc5dd7STejun Heo union { 246bdbc5dd7STejun Heo struct cpu_workqueue_struct __percpu *pcpu; 247bdbc5dd7STejun Heo struct cpu_workqueue_struct *single; 248bdbc5dd7STejun Heo unsigned long v; 249bdbc5dd7STejun Heo } cpu_wq; /* I: cwq's */ 2504690c4abSTejun Heo struct list_head list; /* W: list of all workqueues */ 25173f53c4aSTejun Heo 25273f53c4aSTejun Heo struct mutex flush_mutex; /* protects wq flushing */ 25373f53c4aSTejun Heo int work_color; /* F: current work color */ 25473f53c4aSTejun Heo int flush_color; /* F: current flush color */ 25573f53c4aSTejun Heo atomic_t nr_cwqs_to_flush; /* flush in progress */ 25673f53c4aSTejun Heo struct wq_flusher *first_flusher; /* F: first flusher */ 25773f53c4aSTejun Heo struct list_head flusher_queue; /* F: flush waiters */ 25873f53c4aSTejun Heo struct list_head flusher_overflow; /* F: flush overflow list */ 25973f53c4aSTejun Heo 260f2e005aaSTejun Heo mayday_mask_t mayday_mask; /* cpus requesting rescue */ 261e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 262e22bee78STejun Heo 2639c5a2ba7STejun Heo int nr_drainers; /* W: drain in progress */ 264dcd989cbSTejun Heo int saved_max_active; /* W: saved cwq max_active */ 2654e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2664e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2674e6045f1SJohannes Berg #endif 268b196be89STejun Heo char name[]; /* I: workqueue name */ 2691da177e4SLinus Torvalds }; 2701da177e4SLinus Torvalds 271d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 272d320c038STejun Heo EXPORT_SYMBOL_GPL(system_wq); 273044c782cSValentin Ilie struct workqueue_struct *system_highpri_wq __read_mostly; 2741aabe902SJoonsoo Kim EXPORT_SYMBOL_GPL(system_highpri_wq); 275044c782cSValentin Ilie struct workqueue_struct *system_long_wq __read_mostly; 276d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 277044c782cSValentin Ilie struct workqueue_struct *system_nrt_wq __read_mostly; 278d320c038STejun Heo EXPORT_SYMBOL_GPL(system_nrt_wq); 279044c782cSValentin Ilie struct workqueue_struct *system_unbound_wq __read_mostly; 280f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 281044c782cSValentin Ilie struct workqueue_struct *system_freezable_wq __read_mostly; 28224d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 283044c782cSValentin Ilie struct workqueue_struct *system_nrt_freezable_wq __read_mostly; 28462d3c543SAlan Stern EXPORT_SYMBOL_GPL(system_nrt_freezable_wq); 285d320c038STejun Heo 28697bd2347STejun Heo #define CREATE_TRACE_POINTS 28797bd2347STejun Heo #include <trace/events/workqueue.h> 28897bd2347STejun Heo 2894ce62e9eSTejun Heo #define for_each_worker_pool(pool, gcwq) \ 2903270476aSTejun Heo for ((pool) = &(gcwq)->pools[0]; \ 2913270476aSTejun Heo (pool) < &(gcwq)->pools[NR_WORKER_POOLS]; (pool)++) 2924ce62e9eSTejun Heo 293db7bccf4STejun Heo #define for_each_busy_worker(worker, i, pos, gcwq) \ 294db7bccf4STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ 295db7bccf4STejun Heo hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) 296db7bccf4STejun Heo 297f3421797STejun Heo static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, 298f3421797STejun Heo unsigned int sw) 299f3421797STejun Heo { 300f3421797STejun Heo if (cpu < nr_cpu_ids) { 301f3421797STejun Heo if (sw & 1) { 302f3421797STejun Heo cpu = cpumask_next(cpu, mask); 303f3421797STejun Heo if (cpu < nr_cpu_ids) 304f3421797STejun Heo return cpu; 305f3421797STejun Heo } 306f3421797STejun Heo if (sw & 2) 307f3421797STejun Heo return WORK_CPU_UNBOUND; 308f3421797STejun Heo } 309f3421797STejun Heo return WORK_CPU_NONE; 310f3421797STejun Heo } 311f3421797STejun Heo 312f3421797STejun Heo static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, 313f3421797STejun Heo struct workqueue_struct *wq) 314f3421797STejun Heo { 315f3421797STejun Heo return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); 316f3421797STejun Heo } 317f3421797STejun Heo 31809884951STejun Heo /* 31909884951STejun Heo * CPU iterators 32009884951STejun Heo * 32109884951STejun Heo * An extra gcwq is defined for an invalid cpu number 32209884951STejun Heo * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any 32309884951STejun Heo * specific CPU. The following iterators are similar to 32409884951STejun Heo * for_each_*_cpu() iterators but also considers the unbound gcwq. 32509884951STejun Heo * 32609884951STejun Heo * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND 32709884951STejun Heo * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND 32809884951STejun Heo * for_each_cwq_cpu() : possible CPUs for bound workqueues, 32909884951STejun Heo * WORK_CPU_UNBOUND for unbound workqueues 33009884951STejun Heo */ 331f3421797STejun Heo #define for_each_gcwq_cpu(cpu) \ 332f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ 333f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 334f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) 335f3421797STejun Heo 336f3421797STejun Heo #define for_each_online_gcwq_cpu(cpu) \ 337f3421797STejun Heo for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ 338f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 339f3421797STejun Heo (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) 340f3421797STejun Heo 341f3421797STejun Heo #define for_each_cwq_cpu(cpu, wq) \ 342f3421797STejun Heo for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ 343f3421797STejun Heo (cpu) < WORK_CPU_NONE; \ 344f3421797STejun Heo (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) 345f3421797STejun Heo 346dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 347dc186ad7SThomas Gleixner 348dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 349dc186ad7SThomas Gleixner 35099777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 35199777288SStanislaw Gruszka { 35299777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 35399777288SStanislaw Gruszka } 35499777288SStanislaw Gruszka 355dc186ad7SThomas Gleixner /* 356dc186ad7SThomas Gleixner * fixup_init is called when: 357dc186ad7SThomas Gleixner * - an active object is initialized 358dc186ad7SThomas Gleixner */ 359dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 360dc186ad7SThomas Gleixner { 361dc186ad7SThomas Gleixner struct work_struct *work = addr; 362dc186ad7SThomas Gleixner 363dc186ad7SThomas Gleixner switch (state) { 364dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 365dc186ad7SThomas Gleixner cancel_work_sync(work); 366dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 367dc186ad7SThomas Gleixner return 1; 368dc186ad7SThomas Gleixner default: 369dc186ad7SThomas Gleixner return 0; 370dc186ad7SThomas Gleixner } 371dc186ad7SThomas Gleixner } 372dc186ad7SThomas Gleixner 373dc186ad7SThomas Gleixner /* 374dc186ad7SThomas Gleixner * fixup_activate is called when: 375dc186ad7SThomas Gleixner * - an active object is activated 376dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 377dc186ad7SThomas Gleixner */ 378dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 379dc186ad7SThomas Gleixner { 380dc186ad7SThomas Gleixner struct work_struct *work = addr; 381dc186ad7SThomas Gleixner 382dc186ad7SThomas Gleixner switch (state) { 383dc186ad7SThomas Gleixner 384dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 385dc186ad7SThomas Gleixner /* 386dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 387dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 388dc186ad7SThomas Gleixner * is tracked in the object tracker. 389dc186ad7SThomas Gleixner */ 39022df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 391dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 392dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 393dc186ad7SThomas Gleixner return 0; 394dc186ad7SThomas Gleixner } 395dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 396dc186ad7SThomas Gleixner return 0; 397dc186ad7SThomas Gleixner 398dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 399dc186ad7SThomas Gleixner WARN_ON(1); 400dc186ad7SThomas Gleixner 401dc186ad7SThomas Gleixner default: 402dc186ad7SThomas Gleixner return 0; 403dc186ad7SThomas Gleixner } 404dc186ad7SThomas Gleixner } 405dc186ad7SThomas Gleixner 406dc186ad7SThomas Gleixner /* 407dc186ad7SThomas Gleixner * fixup_free is called when: 408dc186ad7SThomas Gleixner * - an active object is freed 409dc186ad7SThomas Gleixner */ 410dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 411dc186ad7SThomas Gleixner { 412dc186ad7SThomas Gleixner struct work_struct *work = addr; 413dc186ad7SThomas Gleixner 414dc186ad7SThomas Gleixner switch (state) { 415dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 416dc186ad7SThomas Gleixner cancel_work_sync(work); 417dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 418dc186ad7SThomas Gleixner return 1; 419dc186ad7SThomas Gleixner default: 420dc186ad7SThomas Gleixner return 0; 421dc186ad7SThomas Gleixner } 422dc186ad7SThomas Gleixner } 423dc186ad7SThomas Gleixner 424dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 425dc186ad7SThomas Gleixner .name = "work_struct", 42699777288SStanislaw Gruszka .debug_hint = work_debug_hint, 427dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 428dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 429dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 430dc186ad7SThomas Gleixner }; 431dc186ad7SThomas Gleixner 432dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 433dc186ad7SThomas Gleixner { 434dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 435dc186ad7SThomas Gleixner } 436dc186ad7SThomas Gleixner 437dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 438dc186ad7SThomas Gleixner { 439dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 440dc186ad7SThomas Gleixner } 441dc186ad7SThomas Gleixner 442dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 443dc186ad7SThomas Gleixner { 444dc186ad7SThomas Gleixner if (onstack) 445dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 446dc186ad7SThomas Gleixner else 447dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 448dc186ad7SThomas Gleixner } 449dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 450dc186ad7SThomas Gleixner 451dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 452dc186ad7SThomas Gleixner { 453dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 454dc186ad7SThomas Gleixner } 455dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 456dc186ad7SThomas Gleixner 457dc186ad7SThomas Gleixner #else 458dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 459dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 460dc186ad7SThomas Gleixner #endif 461dc186ad7SThomas Gleixner 46295402b38SGautham R Shenoy /* Serializes the accesses to the list of workqueues. */ 46395402b38SGautham R Shenoy static DEFINE_SPINLOCK(workqueue_lock); 4641da177e4SLinus Torvalds static LIST_HEAD(workqueues); 465a0a1a5fdSTejun Heo static bool workqueue_freezing; /* W: have wqs started freezing? */ 4661da177e4SLinus Torvalds 46714441960SOleg Nesterov /* 468e22bee78STejun Heo * The almighty global cpu workqueues. nr_running is the only field 469e22bee78STejun Heo * which is expected to be used frequently by other cpus via 470e22bee78STejun Heo * try_to_wake_up(). Put it in a separate cacheline. 47114441960SOleg Nesterov */ 4728b03ae3cSTejun Heo static DEFINE_PER_CPU(struct global_cwq, global_cwq); 4734ce62e9eSTejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_WORKER_POOLS]); 474f756d5e2SNathan Lynch 475f3421797STejun Heo /* 476f3421797STejun Heo * Global cpu workqueue and nr_running counter for unbound gcwq. The 477f3421797STejun Heo * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its 478f3421797STejun Heo * workers have WORKER_UNBOUND set. 479f3421797STejun Heo */ 480f3421797STejun Heo static struct global_cwq unbound_global_cwq; 4814ce62e9eSTejun Heo static atomic_t unbound_pool_nr_running[NR_WORKER_POOLS] = { 4824ce62e9eSTejun Heo [0 ... NR_WORKER_POOLS - 1] = ATOMIC_INIT(0), /* always 0 */ 4834ce62e9eSTejun Heo }; 484f3421797STejun Heo 485c34056a3STejun Heo static int worker_thread(void *__worker); 4861da177e4SLinus Torvalds 4873270476aSTejun Heo static int worker_pool_pri(struct worker_pool *pool) 4883270476aSTejun Heo { 4893270476aSTejun Heo return pool - pool->gcwq->pools; 4903270476aSTejun Heo } 4913270476aSTejun Heo 4928b03ae3cSTejun Heo static struct global_cwq *get_gcwq(unsigned int cpu) 4931da177e4SLinus Torvalds { 494f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 4958b03ae3cSTejun Heo return &per_cpu(global_cwq, cpu); 496f3421797STejun Heo else 497f3421797STejun Heo return &unbound_global_cwq; 4981da177e4SLinus Torvalds } 4991da177e4SLinus Torvalds 50063d95a91STejun Heo static atomic_t *get_pool_nr_running(struct worker_pool *pool) 501b1f4ec17SOleg Nesterov { 50263d95a91STejun Heo int cpu = pool->gcwq->cpu; 5033270476aSTejun Heo int idx = worker_pool_pri(pool); 50463d95a91STejun Heo 505f3421797STejun Heo if (cpu != WORK_CPU_UNBOUND) 5064ce62e9eSTejun Heo return &per_cpu(pool_nr_running, cpu)[idx]; 507f3421797STejun Heo else 5084ce62e9eSTejun Heo return &unbound_pool_nr_running[idx]; 509b1f4ec17SOleg Nesterov } 510b1f4ec17SOleg Nesterov 5114690c4abSTejun Heo static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, 5124690c4abSTejun Heo struct workqueue_struct *wq) 513a848e3b6SOleg Nesterov { 514f3421797STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 515e06ffa1eSLai Jiangshan if (likely(cpu < nr_cpu_ids)) 516bdbc5dd7STejun Heo return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); 517f3421797STejun Heo } else if (likely(cpu == WORK_CPU_UNBOUND)) 518f3421797STejun Heo return wq->cpu_wq.single; 519f3421797STejun Heo return NULL; 520f3421797STejun Heo } 521a848e3b6SOleg Nesterov 52273f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 52373f53c4aSTejun Heo { 52473f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 52573f53c4aSTejun Heo } 52673f53c4aSTejun Heo 52773f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 52873f53c4aSTejun Heo { 52973f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 53073f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 53173f53c4aSTejun Heo } 53273f53c4aSTejun Heo 53373f53c4aSTejun Heo static int work_next_color(int color) 53473f53c4aSTejun Heo { 53573f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 5361da177e4SLinus Torvalds } 5371da177e4SLinus Torvalds 5384594bf15SDavid Howells /* 539b5490077STejun Heo * While queued, %WORK_STRUCT_CWQ is set and non flag bits of a work's data 540b5490077STejun Heo * contain the pointer to the queued cwq. Once execution starts, the flag 541b5490077STejun Heo * is cleared and the high bits contain OFFQ flags and CPU number. 5427a22ad75STejun Heo * 543bbb68dfaSTejun Heo * set_work_cwq(), set_work_cpu_and_clear_pending(), mark_work_canceling() 544bbb68dfaSTejun Heo * and clear_work_data() can be used to set the cwq, cpu or clear 545bbb68dfaSTejun Heo * work->data. These functions should only be called while the work is 546bbb68dfaSTejun Heo * owned - ie. while the PENDING bit is set. 5477a22ad75STejun Heo * 548bbb68dfaSTejun Heo * get_work_[g]cwq() can be used to obtain the gcwq or cwq corresponding to 549bbb68dfaSTejun Heo * a work. gcwq is available once the work has been queued anywhere after 550bbb68dfaSTejun Heo * initialization until it is sync canceled. cwq is available only while 551bbb68dfaSTejun Heo * the work item is queued. 552bbb68dfaSTejun Heo * 553bbb68dfaSTejun Heo * %WORK_OFFQ_CANCELING is used to mark a work item which is being 554bbb68dfaSTejun Heo * canceled. While being canceled, a work item may have its PENDING set 555bbb68dfaSTejun Heo * but stay off timer and worklist for arbitrarily long and nobody should 556bbb68dfaSTejun Heo * try to steal the PENDING bit. 5574594bf15SDavid Howells */ 5587a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 5597a22ad75STejun Heo unsigned long flags) 5607a22ad75STejun Heo { 5617a22ad75STejun Heo BUG_ON(!work_pending(work)); 5627a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 5637a22ad75STejun Heo } 5647a22ad75STejun Heo 5657a22ad75STejun Heo static void set_work_cwq(struct work_struct *work, 5664690c4abSTejun Heo struct cpu_workqueue_struct *cwq, 5674690c4abSTejun Heo unsigned long extra_flags) 568365970a1SDavid Howells { 5697a22ad75STejun Heo set_work_data(work, (unsigned long)cwq, 570e120153dSTejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); 571365970a1SDavid Howells } 572365970a1SDavid Howells 5738930cabaSTejun Heo static void set_work_cpu_and_clear_pending(struct work_struct *work, 5748930cabaSTejun Heo unsigned int cpu) 5754d707b9fSOleg Nesterov { 57623657bb1STejun Heo /* 57723657bb1STejun Heo * The following wmb is paired with the implied mb in 57823657bb1STejun Heo * test_and_set_bit(PENDING) and ensures all updates to @work made 57923657bb1STejun Heo * here are visible to and precede any updates by the next PENDING 58023657bb1STejun Heo * owner. 58123657bb1STejun Heo */ 58223657bb1STejun Heo smp_wmb(); 583b5490077STejun Heo set_work_data(work, (unsigned long)cpu << WORK_OFFQ_CPU_SHIFT, 0); 5844d707b9fSOleg Nesterov } 5854d707b9fSOleg Nesterov 5867a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 587365970a1SDavid Howells { 58823657bb1STejun Heo smp_wmb(); /* see set_work_cpu_and_clear_pending() */ 5897a22ad75STejun Heo set_work_data(work, WORK_STRUCT_NO_CPU, 0); 5907a22ad75STejun Heo } 5917a22ad75STejun Heo 5927a22ad75STejun Heo static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) 5937a22ad75STejun Heo { 594e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 5957a22ad75STejun Heo 596e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 597e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 598e120153dSTejun Heo else 599e120153dSTejun Heo return NULL; 6007a22ad75STejun Heo } 6017a22ad75STejun Heo 6027a22ad75STejun Heo static struct global_cwq *get_work_gcwq(struct work_struct *work) 6037a22ad75STejun Heo { 604e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 6057a22ad75STejun Heo unsigned int cpu; 6067a22ad75STejun Heo 607e120153dSTejun Heo if (data & WORK_STRUCT_CWQ) 608e120153dSTejun Heo return ((struct cpu_workqueue_struct *) 609bd7bdd43STejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq; 6107a22ad75STejun Heo 611b5490077STejun Heo cpu = data >> WORK_OFFQ_CPU_SHIFT; 612bdbc5dd7STejun Heo if (cpu == WORK_CPU_NONE) 6137a22ad75STejun Heo return NULL; 6147a22ad75STejun Heo 615f3421797STejun Heo BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); 6167a22ad75STejun Heo return get_gcwq(cpu); 617365970a1SDavid Howells } 618365970a1SDavid Howells 619bbb68dfaSTejun Heo static void mark_work_canceling(struct work_struct *work) 620bbb68dfaSTejun Heo { 621bbb68dfaSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 622bbb68dfaSTejun Heo unsigned long cpu = gcwq ? gcwq->cpu : WORK_CPU_NONE; 623bbb68dfaSTejun Heo 624bbb68dfaSTejun Heo set_work_data(work, (cpu << WORK_OFFQ_CPU_SHIFT) | WORK_OFFQ_CANCELING, 625bbb68dfaSTejun Heo WORK_STRUCT_PENDING); 626bbb68dfaSTejun Heo } 627bbb68dfaSTejun Heo 628bbb68dfaSTejun Heo static bool work_is_canceling(struct work_struct *work) 629bbb68dfaSTejun Heo { 630bbb68dfaSTejun Heo unsigned long data = atomic_long_read(&work->data); 631bbb68dfaSTejun Heo 632bbb68dfaSTejun Heo return !(data & WORK_STRUCT_CWQ) && (data & WORK_OFFQ_CANCELING); 633bbb68dfaSTejun Heo } 634bbb68dfaSTejun Heo 635e22bee78STejun Heo /* 6363270476aSTejun Heo * Policy functions. These define the policies on how the global worker 6373270476aSTejun Heo * pools are managed. Unless noted otherwise, these functions assume that 6383270476aSTejun Heo * they're being called with gcwq->lock held. 639e22bee78STejun Heo */ 640e22bee78STejun Heo 64163d95a91STejun Heo static bool __need_more_worker(struct worker_pool *pool) 642649027d7STejun Heo { 6433270476aSTejun Heo return !atomic_read(get_pool_nr_running(pool)); 644649027d7STejun Heo } 645649027d7STejun Heo 646e22bee78STejun Heo /* 647e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 648e22bee78STejun Heo * running workers. 649974271c4STejun Heo * 650974271c4STejun Heo * Note that, because unbound workers never contribute to nr_running, this 651974271c4STejun Heo * function will always return %true for unbound gcwq as long as the 652974271c4STejun Heo * worklist isn't empty. 653e22bee78STejun Heo */ 65463d95a91STejun Heo static bool need_more_worker(struct worker_pool *pool) 655e22bee78STejun Heo { 65663d95a91STejun Heo return !list_empty(&pool->worklist) && __need_more_worker(pool); 657e22bee78STejun Heo } 658e22bee78STejun Heo 659e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 66063d95a91STejun Heo static bool may_start_working(struct worker_pool *pool) 661e22bee78STejun Heo { 66263d95a91STejun Heo return pool->nr_idle; 663e22bee78STejun Heo } 664e22bee78STejun Heo 665e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 66663d95a91STejun Heo static bool keep_working(struct worker_pool *pool) 667e22bee78STejun Heo { 66863d95a91STejun Heo atomic_t *nr_running = get_pool_nr_running(pool); 669e22bee78STejun Heo 6703270476aSTejun Heo return !list_empty(&pool->worklist) && atomic_read(nr_running) <= 1; 671e22bee78STejun Heo } 672e22bee78STejun Heo 673e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 67463d95a91STejun Heo static bool need_to_create_worker(struct worker_pool *pool) 675e22bee78STejun Heo { 67663d95a91STejun Heo return need_more_worker(pool) && !may_start_working(pool); 677e22bee78STejun Heo } 678e22bee78STejun Heo 679e22bee78STejun Heo /* Do I need to be the manager? */ 68063d95a91STejun Heo static bool need_to_manage_workers(struct worker_pool *pool) 681e22bee78STejun Heo { 68263d95a91STejun Heo return need_to_create_worker(pool) || 68311ebea50STejun Heo (pool->flags & POOL_MANAGE_WORKERS); 684e22bee78STejun Heo } 685e22bee78STejun Heo 686e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 68763d95a91STejun Heo static bool too_many_workers(struct worker_pool *pool) 688e22bee78STejun Heo { 68960373152STejun Heo bool managing = mutex_is_locked(&pool->manager_mutex); 69063d95a91STejun Heo int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 69163d95a91STejun Heo int nr_busy = pool->nr_workers - nr_idle; 692e22bee78STejun Heo 693e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 694e22bee78STejun Heo } 695e22bee78STejun Heo 696e22bee78STejun Heo /* 697e22bee78STejun Heo * Wake up functions. 698e22bee78STejun Heo */ 699e22bee78STejun Heo 7007e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 70163d95a91STejun Heo static struct worker *first_worker(struct worker_pool *pool) 7027e11629dSTejun Heo { 70363d95a91STejun Heo if (unlikely(list_empty(&pool->idle_list))) 7047e11629dSTejun Heo return NULL; 7057e11629dSTejun Heo 70663d95a91STejun Heo return list_first_entry(&pool->idle_list, struct worker, entry); 7077e11629dSTejun Heo } 7087e11629dSTejun Heo 7097e11629dSTejun Heo /** 7107e11629dSTejun Heo * wake_up_worker - wake up an idle worker 71163d95a91STejun Heo * @pool: worker pool to wake worker from 7127e11629dSTejun Heo * 71363d95a91STejun Heo * Wake up the first idle worker of @pool. 7147e11629dSTejun Heo * 7157e11629dSTejun Heo * CONTEXT: 7167e11629dSTejun Heo * spin_lock_irq(gcwq->lock). 7177e11629dSTejun Heo */ 71863d95a91STejun Heo static void wake_up_worker(struct worker_pool *pool) 7197e11629dSTejun Heo { 72063d95a91STejun Heo struct worker *worker = first_worker(pool); 7217e11629dSTejun Heo 7227e11629dSTejun Heo if (likely(worker)) 7237e11629dSTejun Heo wake_up_process(worker->task); 7247e11629dSTejun Heo } 7257e11629dSTejun Heo 7264690c4abSTejun Heo /** 727e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 728e22bee78STejun Heo * @task: task waking up 729e22bee78STejun Heo * @cpu: CPU @task is waking up to 730e22bee78STejun Heo * 731e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 732e22bee78STejun Heo * being awoken. 733e22bee78STejun Heo * 734e22bee78STejun Heo * CONTEXT: 735e22bee78STejun Heo * spin_lock_irq(rq->lock) 736e22bee78STejun Heo */ 737e22bee78STejun Heo void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) 738e22bee78STejun Heo { 739e22bee78STejun Heo struct worker *worker = kthread_data(task); 740e22bee78STejun Heo 7412d64672eSSteven Rostedt if (!(worker->flags & WORKER_NOT_RUNNING)) 74263d95a91STejun Heo atomic_inc(get_pool_nr_running(worker->pool)); 743e22bee78STejun Heo } 744e22bee78STejun Heo 745e22bee78STejun Heo /** 746e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 747e22bee78STejun Heo * @task: task going to sleep 748e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 749e22bee78STejun Heo * 750e22bee78STejun Heo * This function is called during schedule() when a busy worker is 751e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 752e22bee78STejun Heo * returning pointer to its task. 753e22bee78STejun Heo * 754e22bee78STejun Heo * CONTEXT: 755e22bee78STejun Heo * spin_lock_irq(rq->lock) 756e22bee78STejun Heo * 757e22bee78STejun Heo * RETURNS: 758e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 759e22bee78STejun Heo */ 760e22bee78STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, 761e22bee78STejun Heo unsigned int cpu) 762e22bee78STejun Heo { 763e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 764bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 76563d95a91STejun Heo atomic_t *nr_running = get_pool_nr_running(pool); 766e22bee78STejun Heo 7672d64672eSSteven Rostedt if (worker->flags & WORKER_NOT_RUNNING) 768e22bee78STejun Heo return NULL; 769e22bee78STejun Heo 770e22bee78STejun Heo /* this can only happen on the local cpu */ 771e22bee78STejun Heo BUG_ON(cpu != raw_smp_processor_id()); 772e22bee78STejun Heo 773e22bee78STejun Heo /* 774e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 775e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 776e22bee78STejun Heo * Please read comment there. 777e22bee78STejun Heo * 778628c78e7STejun Heo * NOT_RUNNING is clear. This means that we're bound to and 779628c78e7STejun Heo * running on the local cpu w/ rq lock held and preemption 780628c78e7STejun Heo * disabled, which in turn means that none else could be 781628c78e7STejun Heo * manipulating idle_list, so dereferencing idle_list without gcwq 782628c78e7STejun Heo * lock is safe. 783e22bee78STejun Heo */ 784bd7bdd43STejun Heo if (atomic_dec_and_test(nr_running) && !list_empty(&pool->worklist)) 78563d95a91STejun Heo to_wakeup = first_worker(pool); 786e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 787e22bee78STejun Heo } 788e22bee78STejun Heo 789e22bee78STejun Heo /** 790e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 791cb444766STejun Heo * @worker: self 792d302f017STejun Heo * @flags: flags to set 793d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 794d302f017STejun Heo * 795e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 796e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 797e22bee78STejun Heo * woken up. 798d302f017STejun Heo * 799cb444766STejun Heo * CONTEXT: 800cb444766STejun Heo * spin_lock_irq(gcwq->lock) 801d302f017STejun Heo */ 802d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 803d302f017STejun Heo bool wakeup) 804d302f017STejun Heo { 805bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 806e22bee78STejun Heo 807cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 808cb444766STejun Heo 809e22bee78STejun Heo /* 810e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 811e22bee78STejun Heo * wake up an idle worker as necessary if requested by 812e22bee78STejun Heo * @wakeup. 813e22bee78STejun Heo */ 814e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 815e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 81663d95a91STejun Heo atomic_t *nr_running = get_pool_nr_running(pool); 817e22bee78STejun Heo 818e22bee78STejun Heo if (wakeup) { 819e22bee78STejun Heo if (atomic_dec_and_test(nr_running) && 820bd7bdd43STejun Heo !list_empty(&pool->worklist)) 82163d95a91STejun Heo wake_up_worker(pool); 822e22bee78STejun Heo } else 823e22bee78STejun Heo atomic_dec(nr_running); 824e22bee78STejun Heo } 825e22bee78STejun Heo 826d302f017STejun Heo worker->flags |= flags; 827d302f017STejun Heo } 828d302f017STejun Heo 829d302f017STejun Heo /** 830e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 831cb444766STejun Heo * @worker: self 832d302f017STejun Heo * @flags: flags to clear 833d302f017STejun Heo * 834e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 835d302f017STejun Heo * 836cb444766STejun Heo * CONTEXT: 837cb444766STejun Heo * spin_lock_irq(gcwq->lock) 838d302f017STejun Heo */ 839d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 840d302f017STejun Heo { 84163d95a91STejun Heo struct worker_pool *pool = worker->pool; 842e22bee78STejun Heo unsigned int oflags = worker->flags; 843e22bee78STejun Heo 844cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 845cb444766STejun Heo 846d302f017STejun Heo worker->flags &= ~flags; 847e22bee78STejun Heo 84842c025f3STejun Heo /* 84942c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 85042c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 85142c025f3STejun Heo * of multiple flags, not a single flag. 85242c025f3STejun Heo */ 853e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 854e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 85563d95a91STejun Heo atomic_inc(get_pool_nr_running(pool)); 856d302f017STejun Heo } 857d302f017STejun Heo 858d302f017STejun Heo /** 859c8e55f36STejun Heo * busy_worker_head - return the busy hash head for a work 860c8e55f36STejun Heo * @gcwq: gcwq of interest 861c8e55f36STejun Heo * @work: work to be hashed 862c8e55f36STejun Heo * 863c8e55f36STejun Heo * Return hash head of @gcwq for @work. 864c8e55f36STejun Heo * 865c8e55f36STejun Heo * CONTEXT: 866c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 867c8e55f36STejun Heo * 868c8e55f36STejun Heo * RETURNS: 869c8e55f36STejun Heo * Pointer to the hash head. 870c8e55f36STejun Heo */ 871c8e55f36STejun Heo static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, 872c8e55f36STejun Heo struct work_struct *work) 873c8e55f36STejun Heo { 874c8e55f36STejun Heo const int base_shift = ilog2(sizeof(struct work_struct)); 875c8e55f36STejun Heo unsigned long v = (unsigned long)work; 876c8e55f36STejun Heo 877c8e55f36STejun Heo /* simple shift and fold hash, do we need something better? */ 878c8e55f36STejun Heo v >>= base_shift; 879c8e55f36STejun Heo v += v >> BUSY_WORKER_HASH_ORDER; 880c8e55f36STejun Heo v &= BUSY_WORKER_HASH_MASK; 881c8e55f36STejun Heo 882c8e55f36STejun Heo return &gcwq->busy_hash[v]; 883c8e55f36STejun Heo } 884c8e55f36STejun Heo 885c8e55f36STejun Heo /** 8868cca0eeaSTejun Heo * __find_worker_executing_work - find worker which is executing a work 8878cca0eeaSTejun Heo * @gcwq: gcwq of interest 8888cca0eeaSTejun Heo * @bwh: hash head as returned by busy_worker_head() 8898cca0eeaSTejun Heo * @work: work to find worker for 8908cca0eeaSTejun Heo * 8918cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. @bwh should be 8928cca0eeaSTejun Heo * the hash head obtained by calling busy_worker_head() with the same 8938cca0eeaSTejun Heo * work. 8948cca0eeaSTejun Heo * 8958cca0eeaSTejun Heo * CONTEXT: 8968cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 8978cca0eeaSTejun Heo * 8988cca0eeaSTejun Heo * RETURNS: 8998cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 9008cca0eeaSTejun Heo * otherwise. 9018cca0eeaSTejun Heo */ 9028cca0eeaSTejun Heo static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, 9038cca0eeaSTejun Heo struct hlist_head *bwh, 9048cca0eeaSTejun Heo struct work_struct *work) 9058cca0eeaSTejun Heo { 9068cca0eeaSTejun Heo struct worker *worker; 9078cca0eeaSTejun Heo struct hlist_node *tmp; 9088cca0eeaSTejun Heo 9098cca0eeaSTejun Heo hlist_for_each_entry(worker, tmp, bwh, hentry) 9108cca0eeaSTejun Heo if (worker->current_work == work) 9118cca0eeaSTejun Heo return worker; 9128cca0eeaSTejun Heo return NULL; 9138cca0eeaSTejun Heo } 9148cca0eeaSTejun Heo 9158cca0eeaSTejun Heo /** 9168cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 9178cca0eeaSTejun Heo * @gcwq: gcwq of interest 9188cca0eeaSTejun Heo * @work: work to find worker for 9198cca0eeaSTejun Heo * 9208cca0eeaSTejun Heo * Find a worker which is executing @work on @gcwq. This function is 9218cca0eeaSTejun Heo * identical to __find_worker_executing_work() except that this 9228cca0eeaSTejun Heo * function calculates @bwh itself. 9238cca0eeaSTejun Heo * 9248cca0eeaSTejun Heo * CONTEXT: 9258cca0eeaSTejun Heo * spin_lock_irq(gcwq->lock). 9268cca0eeaSTejun Heo * 9278cca0eeaSTejun Heo * RETURNS: 9288cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 9298cca0eeaSTejun Heo * otherwise. 9308cca0eeaSTejun Heo */ 9318cca0eeaSTejun Heo static struct worker *find_worker_executing_work(struct global_cwq *gcwq, 9328cca0eeaSTejun Heo struct work_struct *work) 9338cca0eeaSTejun Heo { 9348cca0eeaSTejun Heo return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), 9358cca0eeaSTejun Heo work); 9368cca0eeaSTejun Heo } 9378cca0eeaSTejun Heo 9388cca0eeaSTejun Heo /** 939bf4ede01STejun Heo * move_linked_works - move linked works to a list 940bf4ede01STejun Heo * @work: start of series of works to be scheduled 941bf4ede01STejun Heo * @head: target list to append @work to 942bf4ede01STejun Heo * @nextp: out paramter for nested worklist walking 943bf4ede01STejun Heo * 944bf4ede01STejun Heo * Schedule linked works starting from @work to @head. Work series to 945bf4ede01STejun Heo * be scheduled starts at @work and includes any consecutive work with 946bf4ede01STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 947bf4ede01STejun Heo * 948bf4ede01STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 949bf4ede01STejun Heo * the last scheduled work. This allows move_linked_works() to be 950bf4ede01STejun Heo * nested inside outer list_for_each_entry_safe(). 951bf4ede01STejun Heo * 952bf4ede01STejun Heo * CONTEXT: 953bf4ede01STejun Heo * spin_lock_irq(gcwq->lock). 954bf4ede01STejun Heo */ 955bf4ede01STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 956bf4ede01STejun Heo struct work_struct **nextp) 957bf4ede01STejun Heo { 958bf4ede01STejun Heo struct work_struct *n; 959bf4ede01STejun Heo 960bf4ede01STejun Heo /* 961bf4ede01STejun Heo * Linked worklist will always end before the end of the list, 962bf4ede01STejun Heo * use NULL for list head. 963bf4ede01STejun Heo */ 964bf4ede01STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 965bf4ede01STejun Heo list_move_tail(&work->entry, head); 966bf4ede01STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 967bf4ede01STejun Heo break; 968bf4ede01STejun Heo } 969bf4ede01STejun Heo 970bf4ede01STejun Heo /* 971bf4ede01STejun Heo * If we're already inside safe list traversal and have moved 972bf4ede01STejun Heo * multiple works to the scheduled queue, the next position 973bf4ede01STejun Heo * needs to be updated. 974bf4ede01STejun Heo */ 975bf4ede01STejun Heo if (nextp) 976bf4ede01STejun Heo *nextp = n; 977bf4ede01STejun Heo } 978bf4ede01STejun Heo 979bf4ede01STejun Heo static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) 980bf4ede01STejun Heo { 981bf4ede01STejun Heo struct work_struct *work = list_first_entry(&cwq->delayed_works, 982bf4ede01STejun Heo struct work_struct, entry); 983bf4ede01STejun Heo 984bf4ede01STejun Heo trace_workqueue_activate_work(work); 985bf4ede01STejun Heo move_linked_works(work, &cwq->pool->worklist, NULL); 986bf4ede01STejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 987bf4ede01STejun Heo cwq->nr_active++; 988bf4ede01STejun Heo } 989bf4ede01STejun Heo 990bf4ede01STejun Heo /** 991bf4ede01STejun Heo * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight 992bf4ede01STejun Heo * @cwq: cwq of interest 993bf4ede01STejun Heo * @color: color of work which left the queue 994bf4ede01STejun Heo * @delayed: for a delayed work 995bf4ede01STejun Heo * 996bf4ede01STejun Heo * A work either has completed or is removed from pending queue, 997bf4ede01STejun Heo * decrement nr_in_flight of its cwq and handle workqueue flushing. 998bf4ede01STejun Heo * 999bf4ede01STejun Heo * CONTEXT: 1000bf4ede01STejun Heo * spin_lock_irq(gcwq->lock). 1001bf4ede01STejun Heo */ 1002bf4ede01STejun Heo static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, 1003bf4ede01STejun Heo bool delayed) 1004bf4ede01STejun Heo { 1005bf4ede01STejun Heo /* ignore uncolored works */ 1006bf4ede01STejun Heo if (color == WORK_NO_COLOR) 1007bf4ede01STejun Heo return; 1008bf4ede01STejun Heo 1009bf4ede01STejun Heo cwq->nr_in_flight[color]--; 1010bf4ede01STejun Heo 1011bf4ede01STejun Heo if (!delayed) { 1012bf4ede01STejun Heo cwq->nr_active--; 1013bf4ede01STejun Heo if (!list_empty(&cwq->delayed_works)) { 1014bf4ede01STejun Heo /* one down, submit a delayed one */ 1015bf4ede01STejun Heo if (cwq->nr_active < cwq->max_active) 1016bf4ede01STejun Heo cwq_activate_first_delayed(cwq); 1017bf4ede01STejun Heo } 1018bf4ede01STejun Heo } 1019bf4ede01STejun Heo 1020bf4ede01STejun Heo /* is flush in progress and are we at the flushing tip? */ 1021bf4ede01STejun Heo if (likely(cwq->flush_color != color)) 1022bf4ede01STejun Heo return; 1023bf4ede01STejun Heo 1024bf4ede01STejun Heo /* are there still in-flight works? */ 1025bf4ede01STejun Heo if (cwq->nr_in_flight[color]) 1026bf4ede01STejun Heo return; 1027bf4ede01STejun Heo 1028bf4ede01STejun Heo /* this cwq is done, clear flush_color */ 1029bf4ede01STejun Heo cwq->flush_color = -1; 1030bf4ede01STejun Heo 1031bf4ede01STejun Heo /* 1032bf4ede01STejun Heo * If this was the last cwq, wake up the first flusher. It 1033bf4ede01STejun Heo * will handle the rest. 1034bf4ede01STejun Heo */ 1035bf4ede01STejun Heo if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) 1036bf4ede01STejun Heo complete(&cwq->wq->first_flusher->done); 1037bf4ede01STejun Heo } 1038bf4ede01STejun Heo 103936e227d2STejun Heo /** 1040bbb68dfaSTejun Heo * try_to_grab_pending - steal work item from worklist and disable irq 104136e227d2STejun Heo * @work: work item to steal 104236e227d2STejun Heo * @is_dwork: @work is a delayed_work 1043bbb68dfaSTejun Heo * @flags: place to store irq state 104436e227d2STejun Heo * 104536e227d2STejun Heo * Try to grab PENDING bit of @work. This function can handle @work in any 104636e227d2STejun Heo * stable state - idle, on timer or on worklist. Return values are 104736e227d2STejun Heo * 104836e227d2STejun Heo * 1 if @work was pending and we successfully stole PENDING 104936e227d2STejun Heo * 0 if @work was idle and we claimed PENDING 105036e227d2STejun Heo * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 1051bbb68dfaSTejun Heo * -ENOENT if someone else is canceling @work, this state may persist 1052bbb68dfaSTejun Heo * for arbitrarily long 105336e227d2STejun Heo * 1054bbb68dfaSTejun Heo * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 1055bbb68dfaSTejun Heo * preempted while holding PENDING and @work off queue, preemption must be 1056bbb68dfaSTejun Heo * disabled on entry. This ensures that we don't return -EAGAIN while 1057bbb68dfaSTejun Heo * another task is preempted in this function. 1058bbb68dfaSTejun Heo * 1059bbb68dfaSTejun Heo * On successful return, >= 0, irq is disabled and the caller is 1060bbb68dfaSTejun Heo * responsible for releasing it using local_irq_restore(*@flags). 1061bbb68dfaSTejun Heo * 1062bbb68dfaSTejun Heo * This function is safe to call from any context other than IRQ handler. 1063bbb68dfaSTejun Heo * An IRQ handler may run on top of delayed_work_timer_fn() which can make 1064bbb68dfaSTejun Heo * this function return -EAGAIN perpetually. 1065bf4ede01STejun Heo */ 1066bbb68dfaSTejun Heo static int try_to_grab_pending(struct work_struct *work, bool is_dwork, 1067bbb68dfaSTejun Heo unsigned long *flags) 1068bf4ede01STejun Heo { 1069bf4ede01STejun Heo struct global_cwq *gcwq; 1070bf4ede01STejun Heo 1071bbb68dfaSTejun Heo WARN_ON_ONCE(in_irq()); 1072bbb68dfaSTejun Heo 1073bbb68dfaSTejun Heo local_irq_save(*flags); 1074bbb68dfaSTejun Heo 107536e227d2STejun Heo /* try to steal the timer if it exists */ 107636e227d2STejun Heo if (is_dwork) { 107736e227d2STejun Heo struct delayed_work *dwork = to_delayed_work(work); 107836e227d2STejun Heo 107936e227d2STejun Heo if (likely(del_timer(&dwork->timer))) 108036e227d2STejun Heo return 1; 108136e227d2STejun Heo } 108236e227d2STejun Heo 108336e227d2STejun Heo /* try to claim PENDING the normal way */ 1084bf4ede01STejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 1085bf4ede01STejun Heo return 0; 1086bf4ede01STejun Heo 1087bf4ede01STejun Heo /* 1088bf4ede01STejun Heo * The queueing is in progress, or it is already queued. Try to 1089bf4ede01STejun Heo * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 1090bf4ede01STejun Heo */ 1091bf4ede01STejun Heo gcwq = get_work_gcwq(work); 1092bf4ede01STejun Heo if (!gcwq) 1093bbb68dfaSTejun Heo goto fail; 1094bf4ede01STejun Heo 1095bbb68dfaSTejun Heo spin_lock(&gcwq->lock); 1096bf4ede01STejun Heo if (!list_empty(&work->entry)) { 1097bf4ede01STejun Heo /* 1098bf4ede01STejun Heo * This work is queued, but perhaps we locked the wrong gcwq. 1099bf4ede01STejun Heo * In that case we must see the new value after rmb(), see 1100bf4ede01STejun Heo * insert_work()->wmb(). 1101bf4ede01STejun Heo */ 1102bf4ede01STejun Heo smp_rmb(); 1103bf4ede01STejun Heo if (gcwq == get_work_gcwq(work)) { 1104bf4ede01STejun Heo debug_work_deactivate(work); 1105bf4ede01STejun Heo list_del_init(&work->entry); 1106bf4ede01STejun Heo cwq_dec_nr_in_flight(get_work_cwq(work), 1107bf4ede01STejun Heo get_work_color(work), 1108bf4ede01STejun Heo *work_data_bits(work) & WORK_STRUCT_DELAYED); 110936e227d2STejun Heo 1110bbb68dfaSTejun Heo spin_unlock(&gcwq->lock); 111136e227d2STejun Heo return 1; 1112bf4ede01STejun Heo } 1113bf4ede01STejun Heo } 1114bbb68dfaSTejun Heo spin_unlock(&gcwq->lock); 1115bbb68dfaSTejun Heo fail: 1116bbb68dfaSTejun Heo local_irq_restore(*flags); 1117bbb68dfaSTejun Heo if (work_is_canceling(work)) 1118bbb68dfaSTejun Heo return -ENOENT; 1119bbb68dfaSTejun Heo cpu_relax(); 112036e227d2STejun Heo return -EAGAIN; 1121bf4ede01STejun Heo } 1122bf4ede01STejun Heo 1123bf4ede01STejun Heo /** 11247e11629dSTejun Heo * insert_work - insert a work into gcwq 11254690c4abSTejun Heo * @cwq: cwq @work belongs to 11264690c4abSTejun Heo * @work: work to insert 11274690c4abSTejun Heo * @head: insertion point 11284690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 11294690c4abSTejun Heo * 11307e11629dSTejun Heo * Insert @work which belongs to @cwq into @gcwq after @head. 11317e11629dSTejun Heo * @extra_flags is or'd to work_struct flags. 11324690c4abSTejun Heo * 11334690c4abSTejun Heo * CONTEXT: 11348b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 11351da177e4SLinus Torvalds */ 1136b89deed3SOleg Nesterov static void insert_work(struct cpu_workqueue_struct *cwq, 11374690c4abSTejun Heo struct work_struct *work, struct list_head *head, 11384690c4abSTejun Heo unsigned int extra_flags) 1139b89deed3SOleg Nesterov { 114063d95a91STejun Heo struct worker_pool *pool = cwq->pool; 1141e1d8aa9fSFrederic Weisbecker 11424690c4abSTejun Heo /* we own @work, set data and link */ 11437a22ad75STejun Heo set_work_cwq(work, cwq, extra_flags); 11444690c4abSTejun Heo 11456e84d644SOleg Nesterov /* 11466e84d644SOleg Nesterov * Ensure that we get the right work->data if we see the 11476e84d644SOleg Nesterov * result of list_add() below, see try_to_grab_pending(). 11486e84d644SOleg Nesterov */ 11496e84d644SOleg Nesterov smp_wmb(); 11504690c4abSTejun Heo 11511a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 1152e22bee78STejun Heo 1153e22bee78STejun Heo /* 1154e22bee78STejun Heo * Ensure either worker_sched_deactivated() sees the above 1155e22bee78STejun Heo * list_add_tail() or we see zero nr_running to avoid workers 1156e22bee78STejun Heo * lying around lazily while there are works to be processed. 1157e22bee78STejun Heo */ 1158e22bee78STejun Heo smp_mb(); 1159e22bee78STejun Heo 116063d95a91STejun Heo if (__need_more_worker(pool)) 116163d95a91STejun Heo wake_up_worker(pool); 1162b89deed3SOleg Nesterov } 1163b89deed3SOleg Nesterov 1164c8efcc25STejun Heo /* 1165c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 1166c8efcc25STejun Heo * same workqueue. This is rather expensive and should only be used from 1167c8efcc25STejun Heo * cold paths. 1168c8efcc25STejun Heo */ 1169c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 1170c8efcc25STejun Heo { 1171c8efcc25STejun Heo unsigned long flags; 1172c8efcc25STejun Heo unsigned int cpu; 1173c8efcc25STejun Heo 1174c8efcc25STejun Heo for_each_gcwq_cpu(cpu) { 1175c8efcc25STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 1176c8efcc25STejun Heo struct worker *worker; 1177c8efcc25STejun Heo struct hlist_node *pos; 1178c8efcc25STejun Heo int i; 1179c8efcc25STejun Heo 1180c8efcc25STejun Heo spin_lock_irqsave(&gcwq->lock, flags); 1181c8efcc25STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 1182c8efcc25STejun Heo if (worker->task != current) 1183c8efcc25STejun Heo continue; 1184c8efcc25STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 1185c8efcc25STejun Heo /* 1186c8efcc25STejun Heo * I'm @worker, no locking necessary. See if @work 1187c8efcc25STejun Heo * is headed to the same workqueue. 1188c8efcc25STejun Heo */ 1189c8efcc25STejun Heo return worker->current_cwq->wq == wq; 1190c8efcc25STejun Heo } 1191c8efcc25STejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 1192c8efcc25STejun Heo } 1193c8efcc25STejun Heo return false; 1194c8efcc25STejun Heo } 1195c8efcc25STejun Heo 11964690c4abSTejun Heo static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, 11971da177e4SLinus Torvalds struct work_struct *work) 11981da177e4SLinus Torvalds { 1199502ca9d8STejun Heo struct global_cwq *gcwq; 1200502ca9d8STejun Heo struct cpu_workqueue_struct *cwq; 12011e19ffc6STejun Heo struct list_head *worklist; 12028a2e8e5dSTejun Heo unsigned int work_flags; 1203b75cac93SJoonsoo Kim unsigned int req_cpu = cpu; 12048930cabaSTejun Heo 12058930cabaSTejun Heo /* 12068930cabaSTejun Heo * While a work item is PENDING && off queue, a task trying to 12078930cabaSTejun Heo * steal the PENDING will busy-loop waiting for it to either get 12088930cabaSTejun Heo * queued or lose PENDING. Grabbing PENDING and queueing should 12098930cabaSTejun Heo * happen with IRQ disabled. 12108930cabaSTejun Heo */ 12118930cabaSTejun Heo WARN_ON_ONCE(!irqs_disabled()); 12121da177e4SLinus Torvalds 1213dc186ad7SThomas Gleixner debug_work_activate(work); 12141e19ffc6STejun Heo 1215c8efcc25STejun Heo /* if dying, only works from the same workqueue are allowed */ 12169c5a2ba7STejun Heo if (unlikely(wq->flags & WQ_DRAINING) && 1217c8efcc25STejun Heo WARN_ON_ONCE(!is_chained_work(wq))) 1218e41e704bSTejun Heo return; 1219e41e704bSTejun Heo 1220c7fc77f7STejun Heo /* determine gcwq to use */ 1221c7fc77f7STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 1222c7fc77f7STejun Heo struct global_cwq *last_gcwq; 1223c7fc77f7STejun Heo 122457469821STejun Heo if (cpu == WORK_CPU_UNBOUND) 1225f3421797STejun Heo cpu = raw_smp_processor_id(); 1226f3421797STejun Heo 122718aa9effSTejun Heo /* 1228dbf2576eSTejun Heo * It's multi cpu. If @work was previously on a different 1229dbf2576eSTejun Heo * cpu, it might still be running there, in which case the 1230dbf2576eSTejun Heo * work needs to be queued on that cpu to guarantee 1231dbf2576eSTejun Heo * non-reentrancy. 123218aa9effSTejun Heo */ 1233502ca9d8STejun Heo gcwq = get_gcwq(cpu); 1234dbf2576eSTejun Heo last_gcwq = get_work_gcwq(work); 1235dbf2576eSTejun Heo 1236dbf2576eSTejun Heo if (last_gcwq && last_gcwq != gcwq) { 123718aa9effSTejun Heo struct worker *worker; 123818aa9effSTejun Heo 12398930cabaSTejun Heo spin_lock(&last_gcwq->lock); 124018aa9effSTejun Heo 124118aa9effSTejun Heo worker = find_worker_executing_work(last_gcwq, work); 124218aa9effSTejun Heo 124318aa9effSTejun Heo if (worker && worker->current_cwq->wq == wq) 124418aa9effSTejun Heo gcwq = last_gcwq; 124518aa9effSTejun Heo else { 124618aa9effSTejun Heo /* meh... not running there, queue here */ 12478930cabaSTejun Heo spin_unlock(&last_gcwq->lock); 12488930cabaSTejun Heo spin_lock(&gcwq->lock); 124918aa9effSTejun Heo } 12508930cabaSTejun Heo } else { 12518930cabaSTejun Heo spin_lock(&gcwq->lock); 12528930cabaSTejun Heo } 1253f3421797STejun Heo } else { 1254f3421797STejun Heo gcwq = get_gcwq(WORK_CPU_UNBOUND); 12558930cabaSTejun Heo spin_lock(&gcwq->lock); 1256502ca9d8STejun Heo } 1257502ca9d8STejun Heo 1258502ca9d8STejun Heo /* gcwq determined, get cwq and queue */ 1259502ca9d8STejun Heo cwq = get_cwq(gcwq->cpu, wq); 1260b75cac93SJoonsoo Kim trace_workqueue_queue_work(req_cpu, cwq, work); 1261502ca9d8STejun Heo 1262f5b2552bSDan Carpenter if (WARN_ON(!list_empty(&work->entry))) { 12638930cabaSTejun Heo spin_unlock(&gcwq->lock); 1264f5b2552bSDan Carpenter return; 1265f5b2552bSDan Carpenter } 12661e19ffc6STejun Heo 126773f53c4aSTejun Heo cwq->nr_in_flight[cwq->work_color]++; 12688a2e8e5dSTejun Heo work_flags = work_color_to_flags(cwq->work_color); 12691e19ffc6STejun Heo 12701e19ffc6STejun Heo if (likely(cwq->nr_active < cwq->max_active)) { 1271cdadf009STejun Heo trace_workqueue_activate_work(work); 12721e19ffc6STejun Heo cwq->nr_active++; 12733270476aSTejun Heo worklist = &cwq->pool->worklist; 12748a2e8e5dSTejun Heo } else { 12758a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 12761e19ffc6STejun Heo worklist = &cwq->delayed_works; 12778a2e8e5dSTejun Heo } 12781e19ffc6STejun Heo 12798a2e8e5dSTejun Heo insert_work(cwq, work, worklist, work_flags); 12801e19ffc6STejun Heo 12818930cabaSTejun Heo spin_unlock(&gcwq->lock); 12821da177e4SLinus Torvalds } 12831da177e4SLinus Torvalds 12840fcb78c2SRolf Eike Beer /** 1285c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1286c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1287c1a220e7SZhang Rui * @wq: workqueue to use 1288c1a220e7SZhang Rui * @work: work to queue 1289c1a220e7SZhang Rui * 1290d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 1291c1a220e7SZhang Rui * 1292c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1293c1a220e7SZhang Rui * can't go away. 1294c1a220e7SZhang Rui */ 1295d4283e93STejun Heo bool queue_work_on(int cpu, struct workqueue_struct *wq, 1296d4283e93STejun Heo struct work_struct *work) 1297c1a220e7SZhang Rui { 1298d4283e93STejun Heo bool ret = false; 12998930cabaSTejun Heo unsigned long flags; 13008930cabaSTejun Heo 13018930cabaSTejun Heo local_irq_save(flags); 1302c1a220e7SZhang Rui 130322df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 13044690c4abSTejun Heo __queue_work(cpu, wq, work); 1305d4283e93STejun Heo ret = true; 1306c1a220e7SZhang Rui } 13078930cabaSTejun Heo 13088930cabaSTejun Heo local_irq_restore(flags); 1309c1a220e7SZhang Rui return ret; 1310c1a220e7SZhang Rui } 1311c1a220e7SZhang Rui EXPORT_SYMBOL_GPL(queue_work_on); 1312c1a220e7SZhang Rui 13130a13c00eSTejun Heo /** 13140a13c00eSTejun Heo * queue_work - queue work on a workqueue 13150a13c00eSTejun Heo * @wq: workqueue to use 13160a13c00eSTejun Heo * @work: work to queue 13170a13c00eSTejun Heo * 1318d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 13190a13c00eSTejun Heo * 13200a13c00eSTejun Heo * We queue the work to the CPU on which it was submitted, but if the CPU dies 13210a13c00eSTejun Heo * it can be processed by another CPU. 13220a13c00eSTejun Heo */ 1323d4283e93STejun Heo bool queue_work(struct workqueue_struct *wq, struct work_struct *work) 13240a13c00eSTejun Heo { 132557469821STejun Heo return queue_work_on(WORK_CPU_UNBOUND, wq, work); 13260a13c00eSTejun Heo } 13270a13c00eSTejun Heo EXPORT_SYMBOL_GPL(queue_work); 13280a13c00eSTejun Heo 1329d8e794dfSTejun Heo void delayed_work_timer_fn(unsigned long __data) 13301da177e4SLinus Torvalds { 133152bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 13327a22ad75STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); 13331da177e4SLinus Torvalds 13348930cabaSTejun Heo local_irq_disable(); 13351265057fSTejun Heo __queue_work(dwork->cpu, cwq->wq, &dwork->work); 13368930cabaSTejun Heo local_irq_enable(); 13371da177e4SLinus Torvalds } 1338d8e794dfSTejun Heo EXPORT_SYMBOL_GPL(delayed_work_timer_fn); 13391da177e4SLinus Torvalds 13407beb2edfSTejun Heo static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 13417beb2edfSTejun Heo struct delayed_work *dwork, unsigned long delay) 13427beb2edfSTejun Heo { 13437beb2edfSTejun Heo struct timer_list *timer = &dwork->timer; 13447beb2edfSTejun Heo struct work_struct *work = &dwork->work; 13457beb2edfSTejun Heo unsigned int lcpu; 13467beb2edfSTejun Heo 13477beb2edfSTejun Heo WARN_ON_ONCE(timer->function != delayed_work_timer_fn || 13487beb2edfSTejun Heo timer->data != (unsigned long)dwork); 13497beb2edfSTejun Heo BUG_ON(timer_pending(timer)); 13507beb2edfSTejun Heo BUG_ON(!list_empty(&work->entry)); 13517beb2edfSTejun Heo 13527beb2edfSTejun Heo timer_stats_timer_set_start_info(&dwork->timer); 13537beb2edfSTejun Heo 13547beb2edfSTejun Heo /* 13557beb2edfSTejun Heo * This stores cwq for the moment, for the timer_fn. Note that the 13567beb2edfSTejun Heo * work's gcwq is preserved to allow reentrance detection for 13577beb2edfSTejun Heo * delayed works. 13587beb2edfSTejun Heo */ 13597beb2edfSTejun Heo if (!(wq->flags & WQ_UNBOUND)) { 13607beb2edfSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 13617beb2edfSTejun Heo 1362e42986deSJoonsoo Kim /* 1363e42986deSJoonsoo Kim * If we cannot get the last gcwq from @work directly, 1364e42986deSJoonsoo Kim * select the last CPU such that it avoids unnecessarily 1365e42986deSJoonsoo Kim * triggering non-reentrancy check in __queue_work(). 1366e42986deSJoonsoo Kim */ 1367e42986deSJoonsoo Kim lcpu = cpu; 1368e42986deSJoonsoo Kim if (gcwq) 13697beb2edfSTejun Heo lcpu = gcwq->cpu; 1370e42986deSJoonsoo Kim if (lcpu == WORK_CPU_UNBOUND) 13717beb2edfSTejun Heo lcpu = raw_smp_processor_id(); 13727beb2edfSTejun Heo } else { 13737beb2edfSTejun Heo lcpu = WORK_CPU_UNBOUND; 13747beb2edfSTejun Heo } 13757beb2edfSTejun Heo 13767beb2edfSTejun Heo set_work_cwq(work, get_cwq(lcpu, wq), 0); 13777beb2edfSTejun Heo 13781265057fSTejun Heo dwork->cpu = cpu; 13797beb2edfSTejun Heo timer->expires = jiffies + delay; 13807beb2edfSTejun Heo 13817beb2edfSTejun Heo if (unlikely(cpu != WORK_CPU_UNBOUND)) 13827beb2edfSTejun Heo add_timer_on(timer, cpu); 13837beb2edfSTejun Heo else 13847beb2edfSTejun Heo add_timer(timer); 13857beb2edfSTejun Heo } 13867beb2edfSTejun Heo 13870fcb78c2SRolf Eike Beer /** 13880fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 13890fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 13900fcb78c2SRolf Eike Beer * @wq: workqueue to use 1391af9997e4SRandy Dunlap * @dwork: work to queue 13920fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 13930fcb78c2SRolf Eike Beer * 1394715f1300STejun Heo * Returns %false if @work was already on a queue, %true otherwise. If 1395715f1300STejun Heo * @delay is zero and @dwork is idle, it will be scheduled for immediate 1396715f1300STejun Heo * execution. 13970fcb78c2SRolf Eike Beer */ 1398d4283e93STejun Heo bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 139952bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 14007a6bc1cdSVenkatesh Pallipadi { 140152bad64dSDavid Howells struct work_struct *work = &dwork->work; 1402d4283e93STejun Heo bool ret = false; 14038930cabaSTejun Heo unsigned long flags; 14048930cabaSTejun Heo 1405715f1300STejun Heo if (!delay) 1406715f1300STejun Heo return queue_work_on(cpu, wq, &dwork->work); 1407715f1300STejun Heo 14088930cabaSTejun Heo /* read the comment in __queue_work() */ 14098930cabaSTejun Heo local_irq_save(flags); 14107a6bc1cdSVenkatesh Pallipadi 141122df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 14127beb2edfSTejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 1413d4283e93STejun Heo ret = true; 14147a6bc1cdSVenkatesh Pallipadi } 14158930cabaSTejun Heo 14168930cabaSTejun Heo local_irq_restore(flags); 14177a6bc1cdSVenkatesh Pallipadi return ret; 14187a6bc1cdSVenkatesh Pallipadi } 1419ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(queue_delayed_work_on); 14201da177e4SLinus Torvalds 1421c8e55f36STejun Heo /** 14220a13c00eSTejun Heo * queue_delayed_work - queue work on a workqueue after delay 14230a13c00eSTejun Heo * @wq: workqueue to use 14240a13c00eSTejun Heo * @dwork: delayable work to queue 14250a13c00eSTejun Heo * @delay: number of jiffies to wait before queueing 14260a13c00eSTejun Heo * 1427715f1300STejun Heo * Equivalent to queue_delayed_work_on() but tries to use the local CPU. 14280a13c00eSTejun Heo */ 1429d4283e93STejun Heo bool queue_delayed_work(struct workqueue_struct *wq, 14300a13c00eSTejun Heo struct delayed_work *dwork, unsigned long delay) 14310a13c00eSTejun Heo { 143257469821STejun Heo return queue_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); 14330a13c00eSTejun Heo } 14340a13c00eSTejun Heo EXPORT_SYMBOL_GPL(queue_delayed_work); 14350a13c00eSTejun Heo 14360a13c00eSTejun Heo /** 14378376fe22STejun Heo * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 14388376fe22STejun Heo * @cpu: CPU number to execute work on 14398376fe22STejun Heo * @wq: workqueue to use 14408376fe22STejun Heo * @dwork: work to queue 14418376fe22STejun Heo * @delay: number of jiffies to wait before queueing 14428376fe22STejun Heo * 14438376fe22STejun Heo * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 14448376fe22STejun Heo * modify @dwork's timer so that it expires after @delay. If @delay is 14458376fe22STejun Heo * zero, @work is guaranteed to be scheduled immediately regardless of its 14468376fe22STejun Heo * current state. 14478376fe22STejun Heo * 14488376fe22STejun Heo * Returns %false if @dwork was idle and queued, %true if @dwork was 14498376fe22STejun Heo * pending and its timer was modified. 14508376fe22STejun Heo * 14518376fe22STejun Heo * This function is safe to call from any context other than IRQ handler. 14528376fe22STejun Heo * See try_to_grab_pending() for details. 14538376fe22STejun Heo */ 14548376fe22STejun Heo bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 14558376fe22STejun Heo struct delayed_work *dwork, unsigned long delay) 14568376fe22STejun Heo { 14578376fe22STejun Heo unsigned long flags; 14588376fe22STejun Heo int ret; 14598376fe22STejun Heo 14608376fe22STejun Heo do { 14618376fe22STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 14628376fe22STejun Heo } while (unlikely(ret == -EAGAIN)); 14638376fe22STejun Heo 14648376fe22STejun Heo if (likely(ret >= 0)) { 14658376fe22STejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 14668376fe22STejun Heo local_irq_restore(flags); 14678376fe22STejun Heo } 14688376fe22STejun Heo 14698376fe22STejun Heo /* -ENOENT from try_to_grab_pending() becomes %true */ 14708376fe22STejun Heo return ret; 14718376fe22STejun Heo } 14728376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work_on); 14738376fe22STejun Heo 14748376fe22STejun Heo /** 14758376fe22STejun Heo * mod_delayed_work - modify delay of or queue a delayed work 14768376fe22STejun Heo * @wq: workqueue to use 14778376fe22STejun Heo * @dwork: work to queue 14788376fe22STejun Heo * @delay: number of jiffies to wait before queueing 14798376fe22STejun Heo * 14808376fe22STejun Heo * mod_delayed_work_on() on local CPU. 14818376fe22STejun Heo */ 14828376fe22STejun Heo bool mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dwork, 14838376fe22STejun Heo unsigned long delay) 14848376fe22STejun Heo { 14858376fe22STejun Heo return mod_delayed_work_on(WORK_CPU_UNBOUND, wq, dwork, delay); 14868376fe22STejun Heo } 14878376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work); 14888376fe22STejun Heo 14898376fe22STejun Heo /** 1490c8e55f36STejun Heo * worker_enter_idle - enter idle state 1491c8e55f36STejun Heo * @worker: worker which is entering idle state 1492c8e55f36STejun Heo * 1493c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1494c8e55f36STejun Heo * necessary. 1495c8e55f36STejun Heo * 1496c8e55f36STejun Heo * LOCKING: 1497c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1498c8e55f36STejun Heo */ 1499c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 15001da177e4SLinus Torvalds { 1501bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1502bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 1503c8e55f36STejun Heo 1504c8e55f36STejun Heo BUG_ON(worker->flags & WORKER_IDLE); 1505c8e55f36STejun Heo BUG_ON(!list_empty(&worker->entry) && 1506c8e55f36STejun Heo (worker->hentry.next || worker->hentry.pprev)); 1507c8e55f36STejun Heo 1508cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1509cb444766STejun Heo worker->flags |= WORKER_IDLE; 1510bd7bdd43STejun Heo pool->nr_idle++; 1511e22bee78STejun Heo worker->last_active = jiffies; 1512c8e55f36STejun Heo 1513c8e55f36STejun Heo /* idle_list is LIFO */ 1514bd7bdd43STejun Heo list_add(&worker->entry, &pool->idle_list); 1515db7bccf4STejun Heo 151663d95a91STejun Heo if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 1517628c78e7STejun Heo mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 1518cb444766STejun Heo 1519544ecf31STejun Heo /* 1520628c78e7STejun Heo * Sanity check nr_running. Because gcwq_unbind_fn() releases 1521628c78e7STejun Heo * gcwq->lock between setting %WORKER_UNBOUND and zapping 1522628c78e7STejun Heo * nr_running, the warning may trigger spuriously. Check iff 1523628c78e7STejun Heo * unbind is not in progress. 1524544ecf31STejun Heo */ 1525628c78e7STejun Heo WARN_ON_ONCE(!(gcwq->flags & GCWQ_DISASSOCIATED) && 1526bd7bdd43STejun Heo pool->nr_workers == pool->nr_idle && 152763d95a91STejun Heo atomic_read(get_pool_nr_running(pool))); 1528c8e55f36STejun Heo } 1529c8e55f36STejun Heo 1530c8e55f36STejun Heo /** 1531c8e55f36STejun Heo * worker_leave_idle - leave idle state 1532c8e55f36STejun Heo * @worker: worker which is leaving idle state 1533c8e55f36STejun Heo * 1534c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1535c8e55f36STejun Heo * 1536c8e55f36STejun Heo * LOCKING: 1537c8e55f36STejun Heo * spin_lock_irq(gcwq->lock). 1538c8e55f36STejun Heo */ 1539c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1540c8e55f36STejun Heo { 1541bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1542c8e55f36STejun Heo 1543c8e55f36STejun Heo BUG_ON(!(worker->flags & WORKER_IDLE)); 1544d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1545bd7bdd43STejun Heo pool->nr_idle--; 1546c8e55f36STejun Heo list_del_init(&worker->entry); 1547c8e55f36STejun Heo } 1548c8e55f36STejun Heo 1549e22bee78STejun Heo /** 1550e22bee78STejun Heo * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq 1551e22bee78STejun Heo * @worker: self 1552e22bee78STejun Heo * 1553e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1554e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1555e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1556e22bee78STejun Heo * guaranteed to execute on the cpu. 1557e22bee78STejun Heo * 1558e22bee78STejun Heo * This function is to be used by rogue workers and rescuers to bind 1559e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1560e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1561e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1562e22bee78STejun Heo * verbatim as it's best effort and blocking and gcwq may be 1563e22bee78STejun Heo * [dis]associated in the meantime. 1564e22bee78STejun Heo * 1565f2d5a0eeSTejun Heo * This function tries set_cpus_allowed() and locks gcwq and verifies the 1566f2d5a0eeSTejun Heo * binding against %GCWQ_DISASSOCIATED which is set during 1567f2d5a0eeSTejun Heo * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker 1568f2d5a0eeSTejun Heo * enters idle state or fetches works without dropping lock, it can 1569f2d5a0eeSTejun Heo * guarantee the scheduling requirement described in the first paragraph. 1570e22bee78STejun Heo * 1571e22bee78STejun Heo * CONTEXT: 1572e22bee78STejun Heo * Might sleep. Called without any lock but returns with gcwq->lock 1573e22bee78STejun Heo * held. 1574e22bee78STejun Heo * 1575e22bee78STejun Heo * RETURNS: 1576e22bee78STejun Heo * %true if the associated gcwq is online (@worker is successfully 1577e22bee78STejun Heo * bound), %false if offline. 1578e22bee78STejun Heo */ 1579e22bee78STejun Heo static bool worker_maybe_bind_and_lock(struct worker *worker) 1580972fa1c5SNamhyung Kim __acquires(&gcwq->lock) 1581e22bee78STejun Heo { 1582bd7bdd43STejun Heo struct global_cwq *gcwq = worker->pool->gcwq; 1583e22bee78STejun Heo struct task_struct *task = worker->task; 1584e22bee78STejun Heo 1585e22bee78STejun Heo while (true) { 1586e22bee78STejun Heo /* 1587e22bee78STejun Heo * The following call may fail, succeed or succeed 1588e22bee78STejun Heo * without actually migrating the task to the cpu if 1589e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 1590e22bee78STejun Heo * against GCWQ_DISASSOCIATED. 1591e22bee78STejun Heo */ 1592f3421797STejun Heo if (!(gcwq->flags & GCWQ_DISASSOCIATED)) 1593e22bee78STejun Heo set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); 1594e22bee78STejun Heo 1595e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1596e22bee78STejun Heo if (gcwq->flags & GCWQ_DISASSOCIATED) 1597e22bee78STejun Heo return false; 1598e22bee78STejun Heo if (task_cpu(task) == gcwq->cpu && 1599e22bee78STejun Heo cpumask_equal(¤t->cpus_allowed, 1600e22bee78STejun Heo get_cpu_mask(gcwq->cpu))) 1601e22bee78STejun Heo return true; 1602e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1603e22bee78STejun Heo 16045035b20fSTejun Heo /* 16055035b20fSTejun Heo * We've raced with CPU hot[un]plug. Give it a breather 16065035b20fSTejun Heo * and retry migration. cond_resched() is required here; 16075035b20fSTejun Heo * otherwise, we might deadlock against cpu_stop trying to 16085035b20fSTejun Heo * bring down the CPU on non-preemptive kernel. 16095035b20fSTejun Heo */ 1610e22bee78STejun Heo cpu_relax(); 16115035b20fSTejun Heo cond_resched(); 1612e22bee78STejun Heo } 1613e22bee78STejun Heo } 1614e22bee78STejun Heo 161525511a47STejun Heo struct idle_rebind { 161625511a47STejun Heo int cnt; /* # workers to be rebound */ 161725511a47STejun Heo struct completion done; /* all workers rebound */ 161825511a47STejun Heo }; 161925511a47STejun Heo 1620e22bee78STejun Heo /* 162125511a47STejun Heo * Rebind an idle @worker to its CPU. During CPU onlining, this has to 162225511a47STejun Heo * happen synchronously for idle workers. worker_thread() will test 162325511a47STejun Heo * %WORKER_REBIND before leaving idle and call this function. 162425511a47STejun Heo */ 162525511a47STejun Heo static void idle_worker_rebind(struct worker *worker) 162625511a47STejun Heo { 162725511a47STejun Heo struct global_cwq *gcwq = worker->pool->gcwq; 162825511a47STejun Heo 162925511a47STejun Heo /* CPU must be online at this point */ 163025511a47STejun Heo WARN_ON(!worker_maybe_bind_and_lock(worker)); 163125511a47STejun Heo if (!--worker->idle_rebind->cnt) 163225511a47STejun Heo complete(&worker->idle_rebind->done); 163325511a47STejun Heo spin_unlock_irq(&worker->pool->gcwq->lock); 163425511a47STejun Heo 163525511a47STejun Heo /* we did our part, wait for rebind_workers() to finish up */ 163625511a47STejun Heo wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND)); 163725511a47STejun Heo } 163825511a47STejun Heo 163925511a47STejun Heo /* 164025511a47STejun Heo * Function for @worker->rebind.work used to rebind unbound busy workers to 1641403c821dSTejun Heo * the associated cpu which is coming back online. This is scheduled by 1642403c821dSTejun Heo * cpu up but can race with other cpu hotplug operations and may be 1643403c821dSTejun Heo * executed twice without intervening cpu down. 1644e22bee78STejun Heo */ 164525511a47STejun Heo static void busy_worker_rebind_fn(struct work_struct *work) 1646e22bee78STejun Heo { 1647e22bee78STejun Heo struct worker *worker = container_of(work, struct worker, rebind_work); 1648bd7bdd43STejun Heo struct global_cwq *gcwq = worker->pool->gcwq; 1649e22bee78STejun Heo 1650e22bee78STejun Heo if (worker_maybe_bind_and_lock(worker)) 1651e22bee78STejun Heo worker_clr_flags(worker, WORKER_REBIND); 1652e22bee78STejun Heo 1653e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1654e22bee78STejun Heo } 1655e22bee78STejun Heo 165625511a47STejun Heo /** 165725511a47STejun Heo * rebind_workers - rebind all workers of a gcwq to the associated CPU 165825511a47STejun Heo * @gcwq: gcwq of interest 165925511a47STejun Heo * 166025511a47STejun Heo * @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding 166125511a47STejun Heo * is different for idle and busy ones. 166225511a47STejun Heo * 166325511a47STejun Heo * The idle ones should be rebound synchronously and idle rebinding should 166425511a47STejun Heo * be complete before any worker starts executing work items with 166525511a47STejun Heo * concurrency management enabled; otherwise, scheduler may oops trying to 166625511a47STejun Heo * wake up non-local idle worker from wq_worker_sleeping(). 166725511a47STejun Heo * 166825511a47STejun Heo * This is achieved by repeatedly requesting rebinding until all idle 166925511a47STejun Heo * workers are known to have been rebound under @gcwq->lock and holding all 167025511a47STejun Heo * idle workers from becoming busy until idle rebinding is complete. 167125511a47STejun Heo * 167225511a47STejun Heo * Once idle workers are rebound, busy workers can be rebound as they 167325511a47STejun Heo * finish executing their current work items. Queueing the rebind work at 167425511a47STejun Heo * the head of their scheduled lists is enough. Note that nr_running will 167525511a47STejun Heo * be properbly bumped as busy workers rebind. 167625511a47STejun Heo * 167725511a47STejun Heo * On return, all workers are guaranteed to either be bound or have rebind 167825511a47STejun Heo * work item scheduled. 167925511a47STejun Heo */ 168025511a47STejun Heo static void rebind_workers(struct global_cwq *gcwq) 168125511a47STejun Heo __releases(&gcwq->lock) __acquires(&gcwq->lock) 168225511a47STejun Heo { 168325511a47STejun Heo struct idle_rebind idle_rebind; 168425511a47STejun Heo struct worker_pool *pool; 168525511a47STejun Heo struct worker *worker; 168625511a47STejun Heo struct hlist_node *pos; 168725511a47STejun Heo int i; 168825511a47STejun Heo 168925511a47STejun Heo lockdep_assert_held(&gcwq->lock); 169025511a47STejun Heo 169125511a47STejun Heo for_each_worker_pool(pool, gcwq) 169225511a47STejun Heo lockdep_assert_held(&pool->manager_mutex); 169325511a47STejun Heo 169425511a47STejun Heo /* 169525511a47STejun Heo * Rebind idle workers. Interlocked both ways. We wait for 169625511a47STejun Heo * workers to rebind via @idle_rebind.done. Workers will wait for 169725511a47STejun Heo * us to finish up by watching %WORKER_REBIND. 169825511a47STejun Heo */ 169925511a47STejun Heo init_completion(&idle_rebind.done); 170025511a47STejun Heo retry: 170125511a47STejun Heo idle_rebind.cnt = 1; 170225511a47STejun Heo INIT_COMPLETION(idle_rebind.done); 170325511a47STejun Heo 170425511a47STejun Heo /* set REBIND and kick idle ones, we'll wait for these later */ 170525511a47STejun Heo for_each_worker_pool(pool, gcwq) { 170625511a47STejun Heo list_for_each_entry(worker, &pool->idle_list, entry) { 170725511a47STejun Heo if (worker->flags & WORKER_REBIND) 170825511a47STejun Heo continue; 170925511a47STejun Heo 171025511a47STejun Heo /* morph UNBOUND to REBIND */ 171125511a47STejun Heo worker->flags &= ~WORKER_UNBOUND; 171225511a47STejun Heo worker->flags |= WORKER_REBIND; 171325511a47STejun Heo 171425511a47STejun Heo idle_rebind.cnt++; 171525511a47STejun Heo worker->idle_rebind = &idle_rebind; 171625511a47STejun Heo 171725511a47STejun Heo /* worker_thread() will call idle_worker_rebind() */ 171825511a47STejun Heo wake_up_process(worker->task); 171925511a47STejun Heo } 172025511a47STejun Heo } 172125511a47STejun Heo 172225511a47STejun Heo if (--idle_rebind.cnt) { 172325511a47STejun Heo spin_unlock_irq(&gcwq->lock); 172425511a47STejun Heo wait_for_completion(&idle_rebind.done); 172525511a47STejun Heo spin_lock_irq(&gcwq->lock); 172625511a47STejun Heo /* busy ones might have become idle while waiting, retry */ 172725511a47STejun Heo goto retry; 172825511a47STejun Heo } 172925511a47STejun Heo 173025511a47STejun Heo /* 173125511a47STejun Heo * All idle workers are rebound and waiting for %WORKER_REBIND to 173225511a47STejun Heo * be cleared inside idle_worker_rebind(). Clear and release. 173325511a47STejun Heo * Clearing %WORKER_REBIND from this foreign context is safe 173425511a47STejun Heo * because these workers are still guaranteed to be idle. 173525511a47STejun Heo */ 173625511a47STejun Heo for_each_worker_pool(pool, gcwq) 173725511a47STejun Heo list_for_each_entry(worker, &pool->idle_list, entry) 173825511a47STejun Heo worker->flags &= ~WORKER_REBIND; 173925511a47STejun Heo 174025511a47STejun Heo wake_up_all(&gcwq->rebind_hold); 174125511a47STejun Heo 174225511a47STejun Heo /* rebind busy workers */ 174325511a47STejun Heo for_each_busy_worker(worker, i, pos, gcwq) { 174425511a47STejun Heo struct work_struct *rebind_work = &worker->rebind_work; 1745e2b6a6d5SJoonsoo Kim struct workqueue_struct *wq; 174625511a47STejun Heo 174725511a47STejun Heo /* morph UNBOUND to REBIND */ 174825511a47STejun Heo worker->flags &= ~WORKER_UNBOUND; 174925511a47STejun Heo worker->flags |= WORKER_REBIND; 175025511a47STejun Heo 175125511a47STejun Heo if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, 175225511a47STejun Heo work_data_bits(rebind_work))) 175325511a47STejun Heo continue; 175425511a47STejun Heo 175525511a47STejun Heo debug_work_activate(rebind_work); 1756e2b6a6d5SJoonsoo Kim 1757e2b6a6d5SJoonsoo Kim /* 1758e2b6a6d5SJoonsoo Kim * wq doesn't really matter but let's keep @worker->pool 1759e2b6a6d5SJoonsoo Kim * and @cwq->pool consistent for sanity. 1760e2b6a6d5SJoonsoo Kim */ 1761e2b6a6d5SJoonsoo Kim if (worker_pool_pri(worker->pool)) 1762e2b6a6d5SJoonsoo Kim wq = system_highpri_wq; 1763e2b6a6d5SJoonsoo Kim else 1764e2b6a6d5SJoonsoo Kim wq = system_wq; 1765e2b6a6d5SJoonsoo Kim 1766e2b6a6d5SJoonsoo Kim insert_work(get_cwq(gcwq->cpu, wq), rebind_work, 176725511a47STejun Heo worker->scheduled.next, 176825511a47STejun Heo work_color_to_flags(WORK_NO_COLOR)); 176925511a47STejun Heo } 177025511a47STejun Heo } 177125511a47STejun Heo 1772c34056a3STejun Heo static struct worker *alloc_worker(void) 1773c34056a3STejun Heo { 1774c34056a3STejun Heo struct worker *worker; 1775c34056a3STejun Heo 1776c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1777c8e55f36STejun Heo if (worker) { 1778c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1779affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 178025511a47STejun Heo INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn); 1781e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1782e22bee78STejun Heo worker->flags = WORKER_PREP; 1783c8e55f36STejun Heo } 1784c34056a3STejun Heo return worker; 1785c34056a3STejun Heo } 1786c34056a3STejun Heo 1787c34056a3STejun Heo /** 1788c34056a3STejun Heo * create_worker - create a new workqueue worker 178963d95a91STejun Heo * @pool: pool the new worker will belong to 1790c34056a3STejun Heo * 179163d95a91STejun Heo * Create a new worker which is bound to @pool. The returned worker 1792c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1793c34056a3STejun Heo * destroy_worker(). 1794c34056a3STejun Heo * 1795c34056a3STejun Heo * CONTEXT: 1796c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1797c34056a3STejun Heo * 1798c34056a3STejun Heo * RETURNS: 1799c34056a3STejun Heo * Pointer to the newly created worker. 1800c34056a3STejun Heo */ 1801bc2ae0f5STejun Heo static struct worker *create_worker(struct worker_pool *pool) 1802c34056a3STejun Heo { 180363d95a91STejun Heo struct global_cwq *gcwq = pool->gcwq; 18043270476aSTejun Heo const char *pri = worker_pool_pri(pool) ? "H" : ""; 1805c34056a3STejun Heo struct worker *worker = NULL; 1806f3421797STejun Heo int id = -1; 1807c34056a3STejun Heo 18088b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1809bd7bdd43STejun Heo while (ida_get_new(&pool->worker_ida, &id)) { 18108b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1811bd7bdd43STejun Heo if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL)) 1812c34056a3STejun Heo goto fail; 18138b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1814c34056a3STejun Heo } 18158b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1816c34056a3STejun Heo 1817c34056a3STejun Heo worker = alloc_worker(); 1818c34056a3STejun Heo if (!worker) 1819c34056a3STejun Heo goto fail; 1820c34056a3STejun Heo 1821bd7bdd43STejun Heo worker->pool = pool; 1822c34056a3STejun Heo worker->id = id; 1823c34056a3STejun Heo 1824bc2ae0f5STejun Heo if (gcwq->cpu != WORK_CPU_UNBOUND) 182594dcf29aSEric Dumazet worker->task = kthread_create_on_node(worker_thread, 18263270476aSTejun Heo worker, cpu_to_node(gcwq->cpu), 18273270476aSTejun Heo "kworker/%u:%d%s", gcwq->cpu, id, pri); 1828f3421797STejun Heo else 1829f3421797STejun Heo worker->task = kthread_create(worker_thread, worker, 18303270476aSTejun Heo "kworker/u:%d%s", id, pri); 1831c34056a3STejun Heo if (IS_ERR(worker->task)) 1832c34056a3STejun Heo goto fail; 1833c34056a3STejun Heo 18343270476aSTejun Heo if (worker_pool_pri(pool)) 18353270476aSTejun Heo set_user_nice(worker->task, HIGHPRI_NICE_LEVEL); 18363270476aSTejun Heo 1837db7bccf4STejun Heo /* 1838bc2ae0f5STejun Heo * Determine CPU binding of the new worker depending on 1839bc2ae0f5STejun Heo * %GCWQ_DISASSOCIATED. The caller is responsible for ensuring the 1840bc2ae0f5STejun Heo * flag remains stable across this function. See the comments 1841bc2ae0f5STejun Heo * above the flag definition for details. 1842bc2ae0f5STejun Heo * 1843bc2ae0f5STejun Heo * As an unbound worker may later become a regular one if CPU comes 1844bc2ae0f5STejun Heo * online, make sure every worker has %PF_THREAD_BOUND set. 1845db7bccf4STejun Heo */ 1846bc2ae0f5STejun Heo if (!(gcwq->flags & GCWQ_DISASSOCIATED)) { 18478b03ae3cSTejun Heo kthread_bind(worker->task, gcwq->cpu); 1848bc2ae0f5STejun Heo } else { 1849db7bccf4STejun Heo worker->task->flags |= PF_THREAD_BOUND; 1850f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1851f3421797STejun Heo } 1852c34056a3STejun Heo 1853c34056a3STejun Heo return worker; 1854c34056a3STejun Heo fail: 1855c34056a3STejun Heo if (id >= 0) { 18568b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1857bd7bdd43STejun Heo ida_remove(&pool->worker_ida, id); 18588b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 1859c34056a3STejun Heo } 1860c34056a3STejun Heo kfree(worker); 1861c34056a3STejun Heo return NULL; 1862c34056a3STejun Heo } 1863c34056a3STejun Heo 1864c34056a3STejun Heo /** 1865c34056a3STejun Heo * start_worker - start a newly created worker 1866c34056a3STejun Heo * @worker: worker to start 1867c34056a3STejun Heo * 1868c8e55f36STejun Heo * Make the gcwq aware of @worker and start it. 1869c34056a3STejun Heo * 1870c34056a3STejun Heo * CONTEXT: 18718b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 1872c34056a3STejun Heo */ 1873c34056a3STejun Heo static void start_worker(struct worker *worker) 1874c34056a3STejun Heo { 1875cb444766STejun Heo worker->flags |= WORKER_STARTED; 1876bd7bdd43STejun Heo worker->pool->nr_workers++; 1877c8e55f36STejun Heo worker_enter_idle(worker); 1878c34056a3STejun Heo wake_up_process(worker->task); 1879c34056a3STejun Heo } 1880c34056a3STejun Heo 1881c34056a3STejun Heo /** 1882c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1883c34056a3STejun Heo * @worker: worker to be destroyed 1884c34056a3STejun Heo * 1885c8e55f36STejun Heo * Destroy @worker and adjust @gcwq stats accordingly. 1886c8e55f36STejun Heo * 1887c8e55f36STejun Heo * CONTEXT: 1888c8e55f36STejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 1889c34056a3STejun Heo */ 1890c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1891c34056a3STejun Heo { 1892bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1893bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 1894c34056a3STejun Heo int id = worker->id; 1895c34056a3STejun Heo 1896c34056a3STejun Heo /* sanity check frenzy */ 1897c34056a3STejun Heo BUG_ON(worker->current_work); 1898affee4b2STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 1899c34056a3STejun Heo 1900c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1901bd7bdd43STejun Heo pool->nr_workers--; 1902c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1903bd7bdd43STejun Heo pool->nr_idle--; 1904c8e55f36STejun Heo 1905c8e55f36STejun Heo list_del_init(&worker->entry); 1906cb444766STejun Heo worker->flags |= WORKER_DIE; 1907c8e55f36STejun Heo 1908c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 1909c8e55f36STejun Heo 1910c34056a3STejun Heo kthread_stop(worker->task); 1911c34056a3STejun Heo kfree(worker); 1912c34056a3STejun Heo 19138b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 1914bd7bdd43STejun Heo ida_remove(&pool->worker_ida, id); 1915c34056a3STejun Heo } 1916c34056a3STejun Heo 191763d95a91STejun Heo static void idle_worker_timeout(unsigned long __pool) 1918e22bee78STejun Heo { 191963d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 192063d95a91STejun Heo struct global_cwq *gcwq = pool->gcwq; 1921e22bee78STejun Heo 1922e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1923e22bee78STejun Heo 192463d95a91STejun Heo if (too_many_workers(pool)) { 1925e22bee78STejun Heo struct worker *worker; 1926e22bee78STejun Heo unsigned long expires; 1927e22bee78STejun Heo 1928e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 192963d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 1930e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1931e22bee78STejun Heo 1932e22bee78STejun Heo if (time_before(jiffies, expires)) 193363d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 1934e22bee78STejun Heo else { 1935e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 193611ebea50STejun Heo pool->flags |= POOL_MANAGE_WORKERS; 193763d95a91STejun Heo wake_up_worker(pool); 1938e22bee78STejun Heo } 1939e22bee78STejun Heo } 1940e22bee78STejun Heo 1941e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1942e22bee78STejun Heo } 1943e22bee78STejun Heo 1944e22bee78STejun Heo static bool send_mayday(struct work_struct *work) 1945e22bee78STejun Heo { 1946e22bee78STejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1947e22bee78STejun Heo struct workqueue_struct *wq = cwq->wq; 1948f3421797STejun Heo unsigned int cpu; 1949e22bee78STejun Heo 1950e22bee78STejun Heo if (!(wq->flags & WQ_RESCUER)) 1951e22bee78STejun Heo return false; 1952e22bee78STejun Heo 1953e22bee78STejun Heo /* mayday mayday mayday */ 1954bd7bdd43STejun Heo cpu = cwq->pool->gcwq->cpu; 1955f3421797STejun Heo /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1956f3421797STejun Heo if (cpu == WORK_CPU_UNBOUND) 1957f3421797STejun Heo cpu = 0; 1958f2e005aaSTejun Heo if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) 1959e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1960e22bee78STejun Heo return true; 1961e22bee78STejun Heo } 1962e22bee78STejun Heo 196363d95a91STejun Heo static void gcwq_mayday_timeout(unsigned long __pool) 1964e22bee78STejun Heo { 196563d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 196663d95a91STejun Heo struct global_cwq *gcwq = pool->gcwq; 1967e22bee78STejun Heo struct work_struct *work; 1968e22bee78STejun Heo 1969e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 1970e22bee78STejun Heo 197163d95a91STejun Heo if (need_to_create_worker(pool)) { 1972e22bee78STejun Heo /* 1973e22bee78STejun Heo * We've been trying to create a new worker but 1974e22bee78STejun Heo * haven't been successful. We might be hitting an 1975e22bee78STejun Heo * allocation deadlock. Send distress signals to 1976e22bee78STejun Heo * rescuers. 1977e22bee78STejun Heo */ 197863d95a91STejun Heo list_for_each_entry(work, &pool->worklist, entry) 1979e22bee78STejun Heo send_mayday(work); 1980e22bee78STejun Heo } 1981e22bee78STejun Heo 1982e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 1983e22bee78STejun Heo 198463d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 1985e22bee78STejun Heo } 1986e22bee78STejun Heo 1987e22bee78STejun Heo /** 1988e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 198963d95a91STejun Heo * @pool: pool to create a new worker for 1990e22bee78STejun Heo * 199163d95a91STejun Heo * Create a new worker for @pool if necessary. @pool is guaranteed to 1992e22bee78STejun Heo * have at least one idle worker on return from this function. If 1993e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 199463d95a91STejun Heo * sent to all rescuers with works scheduled on @pool to resolve 1995e22bee78STejun Heo * possible allocation deadlock. 1996e22bee78STejun Heo * 1997e22bee78STejun Heo * On return, need_to_create_worker() is guaranteed to be false and 1998e22bee78STejun Heo * may_start_working() true. 1999e22bee78STejun Heo * 2000e22bee78STejun Heo * LOCKING: 2001e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2002e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 2003e22bee78STejun Heo * manager. 2004e22bee78STejun Heo * 2005e22bee78STejun Heo * RETURNS: 2006e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 2007e22bee78STejun Heo * otherwise. 2008e22bee78STejun Heo */ 200963d95a91STejun Heo static bool maybe_create_worker(struct worker_pool *pool) 201006bd6ebfSNamhyung Kim __releases(&gcwq->lock) 201106bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 2012e22bee78STejun Heo { 201363d95a91STejun Heo struct global_cwq *gcwq = pool->gcwq; 201463d95a91STejun Heo 201563d95a91STejun Heo if (!need_to_create_worker(pool)) 2016e22bee78STejun Heo return false; 2017e22bee78STejun Heo restart: 20189f9c2364STejun Heo spin_unlock_irq(&gcwq->lock); 20199f9c2364STejun Heo 2020e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 202163d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 2022e22bee78STejun Heo 2023e22bee78STejun Heo while (true) { 2024e22bee78STejun Heo struct worker *worker; 2025e22bee78STejun Heo 2026bc2ae0f5STejun Heo worker = create_worker(pool); 2027e22bee78STejun Heo if (worker) { 202863d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 2029e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 2030e22bee78STejun Heo start_worker(worker); 203163d95a91STejun Heo BUG_ON(need_to_create_worker(pool)); 2032e22bee78STejun Heo return true; 2033e22bee78STejun Heo } 2034e22bee78STejun Heo 203563d95a91STejun Heo if (!need_to_create_worker(pool)) 2036e22bee78STejun Heo break; 2037e22bee78STejun Heo 2038e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 2039e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 20409f9c2364STejun Heo 204163d95a91STejun Heo if (!need_to_create_worker(pool)) 2042e22bee78STejun Heo break; 2043e22bee78STejun Heo } 2044e22bee78STejun Heo 204563d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 2046e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 204763d95a91STejun Heo if (need_to_create_worker(pool)) 2048e22bee78STejun Heo goto restart; 2049e22bee78STejun Heo return true; 2050e22bee78STejun Heo } 2051e22bee78STejun Heo 2052e22bee78STejun Heo /** 2053e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 205463d95a91STejun Heo * @pool: pool to destroy workers for 2055e22bee78STejun Heo * 205663d95a91STejun Heo * Destroy @pool workers which have been idle for longer than 2057e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 2058e22bee78STejun Heo * 2059e22bee78STejun Heo * LOCKING: 2060e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2061e22bee78STejun Heo * multiple times. Called only from manager. 2062e22bee78STejun Heo * 2063e22bee78STejun Heo * RETURNS: 2064e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true 2065e22bee78STejun Heo * otherwise. 2066e22bee78STejun Heo */ 206763d95a91STejun Heo static bool maybe_destroy_workers(struct worker_pool *pool) 2068e22bee78STejun Heo { 2069e22bee78STejun Heo bool ret = false; 2070e22bee78STejun Heo 207163d95a91STejun Heo while (too_many_workers(pool)) { 2072e22bee78STejun Heo struct worker *worker; 2073e22bee78STejun Heo unsigned long expires; 2074e22bee78STejun Heo 207563d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 2076e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 2077e22bee78STejun Heo 2078e22bee78STejun Heo if (time_before(jiffies, expires)) { 207963d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 2080e22bee78STejun Heo break; 2081e22bee78STejun Heo } 2082e22bee78STejun Heo 2083e22bee78STejun Heo destroy_worker(worker); 2084e22bee78STejun Heo ret = true; 2085e22bee78STejun Heo } 2086e22bee78STejun Heo 2087e22bee78STejun Heo return ret; 2088e22bee78STejun Heo } 2089e22bee78STejun Heo 2090e22bee78STejun Heo /** 2091e22bee78STejun Heo * manage_workers - manage worker pool 2092e22bee78STejun Heo * @worker: self 2093e22bee78STejun Heo * 2094e22bee78STejun Heo * Assume the manager role and manage gcwq worker pool @worker belongs 2095e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 2096e22bee78STejun Heo * gcwq. The exclusion is handled automatically by this function. 2097e22bee78STejun Heo * 2098e22bee78STejun Heo * The caller can safely start processing works on false return. On 2099e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 2100e22bee78STejun Heo * and may_start_working() is true. 2101e22bee78STejun Heo * 2102e22bee78STejun Heo * CONTEXT: 2103e22bee78STejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2104e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 2105e22bee78STejun Heo * 2106e22bee78STejun Heo * RETURNS: 2107e22bee78STejun Heo * false if no action was taken and gcwq->lock stayed locked, true if 2108e22bee78STejun Heo * some action was taken. 2109e22bee78STejun Heo */ 2110e22bee78STejun Heo static bool manage_workers(struct worker *worker) 2111e22bee78STejun Heo { 211263d95a91STejun Heo struct worker_pool *pool = worker->pool; 2113e22bee78STejun Heo bool ret = false; 2114e22bee78STejun Heo 211560373152STejun Heo if (!mutex_trylock(&pool->manager_mutex)) 2116e22bee78STejun Heo return ret; 2117e22bee78STejun Heo 211811ebea50STejun Heo pool->flags &= ~POOL_MANAGE_WORKERS; 2119e22bee78STejun Heo 2120e22bee78STejun Heo /* 2121e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 2122e22bee78STejun Heo * on return. 2123e22bee78STejun Heo */ 212463d95a91STejun Heo ret |= maybe_destroy_workers(pool); 212563d95a91STejun Heo ret |= maybe_create_worker(pool); 2126e22bee78STejun Heo 212760373152STejun Heo mutex_unlock(&pool->manager_mutex); 2128e22bee78STejun Heo return ret; 2129e22bee78STejun Heo } 2130e22bee78STejun Heo 2131a62428c0STejun Heo /** 2132a62428c0STejun Heo * process_one_work - process single work 2133c34056a3STejun Heo * @worker: self 2134a62428c0STejun Heo * @work: work to process 2135a62428c0STejun Heo * 2136a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 2137a62428c0STejun Heo * process a single work including synchronization against and 2138a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 2139a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 2140a62428c0STejun Heo * call this function to process a work. 2141a62428c0STejun Heo * 2142a62428c0STejun Heo * CONTEXT: 21438b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which is released and regrabbed. 2144a62428c0STejun Heo */ 2145c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 214606bd6ebfSNamhyung Kim __releases(&gcwq->lock) 214706bd6ebfSNamhyung Kim __acquires(&gcwq->lock) 21481da177e4SLinus Torvalds { 21497e11629dSTejun Heo struct cpu_workqueue_struct *cwq = get_work_cwq(work); 2150bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2151bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 2152c8e55f36STejun Heo struct hlist_head *bwh = busy_worker_head(gcwq, work); 2153fb0e7bebSTejun Heo bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 21546bb49e59SDavid Howells work_func_t f = work->func; 215573f53c4aSTejun Heo int work_color; 21567e11629dSTejun Heo struct worker *collision; 21574e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 21584e6045f1SJohannes Berg /* 2159a62428c0STejun Heo * It is permissible to free the struct work_struct from 2160a62428c0STejun Heo * inside the function that is called from it, this we need to 2161a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 2162a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 2163a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 21644e6045f1SJohannes Berg */ 21654d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 21664d82a1deSPeter Zijlstra 21674d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 21684e6045f1SJohannes Berg #endif 21696fec10a1STejun Heo /* 21706fec10a1STejun Heo * Ensure we're on the correct CPU. DISASSOCIATED test is 21716fec10a1STejun Heo * necessary to avoid spurious warnings from rescuers servicing the 21726fec10a1STejun Heo * unbound or a disassociated gcwq. 21736fec10a1STejun Heo */ 217425511a47STejun Heo WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) && 21756fec10a1STejun Heo !(gcwq->flags & GCWQ_DISASSOCIATED) && 217625511a47STejun Heo raw_smp_processor_id() != gcwq->cpu); 217725511a47STejun Heo 21787e11629dSTejun Heo /* 21797e11629dSTejun Heo * A single work shouldn't be executed concurrently by 21807e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 21817e11629dSTejun Heo * already processing the work. If so, defer the work to the 21827e11629dSTejun Heo * currently executing one. 21837e11629dSTejun Heo */ 21847e11629dSTejun Heo collision = __find_worker_executing_work(gcwq, bwh, work); 21857e11629dSTejun Heo if (unlikely(collision)) { 21867e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 21877e11629dSTejun Heo return; 21887e11629dSTejun Heo } 21891da177e4SLinus Torvalds 21908930cabaSTejun Heo /* claim and dequeue */ 21911da177e4SLinus Torvalds debug_work_deactivate(work); 2192c8e55f36STejun Heo hlist_add_head(&worker->hentry, bwh); 2193c34056a3STejun Heo worker->current_work = work; 21948cca0eeaSTejun Heo worker->current_cwq = cwq; 219573f53c4aSTejun Heo work_color = get_work_color(work); 21967a22ad75STejun Heo 2197a62428c0STejun Heo list_del_init(&work->entry); 2198a62428c0STejun Heo 2199649027d7STejun Heo /* 2200fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 2201fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 2202fb0e7bebSTejun Heo */ 2203fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2204fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 2205fb0e7bebSTejun Heo 2206974271c4STejun Heo /* 2207974271c4STejun Heo * Unbound gcwq isn't concurrency managed and work items should be 2208974271c4STejun Heo * executed ASAP. Wake up another worker if necessary. 2209974271c4STejun Heo */ 221063d95a91STejun Heo if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) 221163d95a91STejun Heo wake_up_worker(pool); 2212974271c4STejun Heo 22138930cabaSTejun Heo /* 221423657bb1STejun Heo * Record the last CPU and clear PENDING which should be the last 221523657bb1STejun Heo * update to @work. Also, do this inside @gcwq->lock so that 221623657bb1STejun Heo * PENDING and queued state changes happen together while IRQ is 221723657bb1STejun Heo * disabled. 22188930cabaSTejun Heo */ 22198930cabaSTejun Heo set_work_cpu_and_clear_pending(work, gcwq->cpu); 22201da177e4SLinus Torvalds 22218930cabaSTejun Heo spin_unlock_irq(&gcwq->lock); 2222959d1af8STejun Heo 2223e159489bSTejun Heo lock_map_acquire_read(&cwq->wq->lockdep_map); 22243295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 2225e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 222665f27f38SDavid Howells f(work); 2227e36c886aSArjan van de Ven /* 2228e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 2229e36c886aSArjan van de Ven * point will only record its address. 2230e36c886aSArjan van de Ven */ 2231e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 22323295f0efSIngo Molnar lock_map_release(&lockdep_map); 22333295f0efSIngo Molnar lock_map_release(&cwq->wq->lockdep_map); 22341da177e4SLinus Torvalds 2235d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 2236044c782cSValentin Ilie pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" 2237044c782cSValentin Ilie " last function: %pf\n", 2238044c782cSValentin Ilie current->comm, preempt_count(), task_pid_nr(current), f); 2239d5abe669SPeter Zijlstra debug_show_held_locks(current); 2240d5abe669SPeter Zijlstra dump_stack(); 2241d5abe669SPeter Zijlstra } 2242d5abe669SPeter Zijlstra 22438b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2244a62428c0STejun Heo 2245fb0e7bebSTejun Heo /* clear cpu intensive status */ 2246fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2247fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 2248fb0e7bebSTejun Heo 2249a62428c0STejun Heo /* we're done with it, release */ 2250c8e55f36STejun Heo hlist_del_init(&worker->hentry); 2251c34056a3STejun Heo worker->current_work = NULL; 22528cca0eeaSTejun Heo worker->current_cwq = NULL; 22538a2e8e5dSTejun Heo cwq_dec_nr_in_flight(cwq, work_color, false); 22541da177e4SLinus Torvalds } 22551da177e4SLinus Torvalds 2256affee4b2STejun Heo /** 2257affee4b2STejun Heo * process_scheduled_works - process scheduled works 2258affee4b2STejun Heo * @worker: self 2259affee4b2STejun Heo * 2260affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 2261affee4b2STejun Heo * may change while processing a work, so this function repeatedly 2262affee4b2STejun Heo * fetches a work from the top and executes it. 2263affee4b2STejun Heo * 2264affee4b2STejun Heo * CONTEXT: 22658b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock) which may be released and regrabbed 2266affee4b2STejun Heo * multiple times. 2267affee4b2STejun Heo */ 2268affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 22691da177e4SLinus Torvalds { 2270affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 2271affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 2272a62428c0STejun Heo struct work_struct, entry); 2273c34056a3STejun Heo process_one_work(worker, work); 2274a62428c0STejun Heo } 22751da177e4SLinus Torvalds } 22761da177e4SLinus Torvalds 22774690c4abSTejun Heo /** 22784690c4abSTejun Heo * worker_thread - the worker thread function 2279c34056a3STejun Heo * @__worker: self 22804690c4abSTejun Heo * 2281e22bee78STejun Heo * The gcwq worker thread function. There's a single dynamic pool of 2282e22bee78STejun Heo * these per each cpu. These workers process all works regardless of 2283e22bee78STejun Heo * their specific target workqueue. The only exception is works which 2284e22bee78STejun Heo * belong to workqueues with a rescuer which will be explained in 2285e22bee78STejun Heo * rescuer_thread(). 22864690c4abSTejun Heo */ 2287c34056a3STejun Heo static int worker_thread(void *__worker) 22881da177e4SLinus Torvalds { 2289c34056a3STejun Heo struct worker *worker = __worker; 2290bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2291bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 22921da177e4SLinus Torvalds 2293e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 2294e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 2295c8e55f36STejun Heo woke_up: 22968b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 2297affee4b2STejun Heo 229825511a47STejun Heo /* 229925511a47STejun Heo * DIE can be set only while idle and REBIND set while busy has 230025511a47STejun Heo * @worker->rebind_work scheduled. Checking here is enough. 230125511a47STejun Heo */ 230225511a47STejun Heo if (unlikely(worker->flags & (WORKER_REBIND | WORKER_DIE))) { 2303c8e55f36STejun Heo spin_unlock_irq(&gcwq->lock); 230425511a47STejun Heo 230525511a47STejun Heo if (worker->flags & WORKER_DIE) { 2306e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 2307c8e55f36STejun Heo return 0; 2308c8e55f36STejun Heo } 2309c8e55f36STejun Heo 231025511a47STejun Heo idle_worker_rebind(worker); 231125511a47STejun Heo goto woke_up; 231225511a47STejun Heo } 231325511a47STejun Heo 2314c8e55f36STejun Heo worker_leave_idle(worker); 2315db7bccf4STejun Heo recheck: 2316e22bee78STejun Heo /* no more worker necessary? */ 231763d95a91STejun Heo if (!need_more_worker(pool)) 2318e22bee78STejun Heo goto sleep; 2319e22bee78STejun Heo 2320e22bee78STejun Heo /* do we need to manage? */ 232163d95a91STejun Heo if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 2322e22bee78STejun Heo goto recheck; 2323e22bee78STejun Heo 2324c8e55f36STejun Heo /* 2325c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 2326c8e55f36STejun Heo * preparing to process a work or actually processing it. 2327c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 2328c8e55f36STejun Heo */ 2329c8e55f36STejun Heo BUG_ON(!list_empty(&worker->scheduled)); 2330c8e55f36STejun Heo 2331e22bee78STejun Heo /* 2332e22bee78STejun Heo * When control reaches this point, we're guaranteed to have 2333e22bee78STejun Heo * at least one idle worker or that someone else has already 2334e22bee78STejun Heo * assumed the manager role. 2335e22bee78STejun Heo */ 2336e22bee78STejun Heo worker_clr_flags(worker, WORKER_PREP); 2337e22bee78STejun Heo 2338e22bee78STejun Heo do { 2339affee4b2STejun Heo struct work_struct *work = 2340bd7bdd43STejun Heo list_first_entry(&pool->worklist, 2341affee4b2STejun Heo struct work_struct, entry); 2342affee4b2STejun Heo 2343c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 2344affee4b2STejun Heo /* optimization path, not strictly necessary */ 2345affee4b2STejun Heo process_one_work(worker, work); 2346affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 2347affee4b2STejun Heo process_scheduled_works(worker); 2348affee4b2STejun Heo } else { 2349c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 2350affee4b2STejun Heo process_scheduled_works(worker); 2351affee4b2STejun Heo } 235263d95a91STejun Heo } while (keep_working(pool)); 2353affee4b2STejun Heo 2354e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 2355d313dd85STejun Heo sleep: 235663d95a91STejun Heo if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) 2357e22bee78STejun Heo goto recheck; 2358d313dd85STejun Heo 2359c8e55f36STejun Heo /* 2360e22bee78STejun Heo * gcwq->lock is held and there's no work to process and no 2361e22bee78STejun Heo * need to manage, sleep. Workers are woken up only while 2362e22bee78STejun Heo * holding gcwq->lock or from local cpu, so setting the 2363e22bee78STejun Heo * current state before releasing gcwq->lock is enough to 2364e22bee78STejun Heo * prevent losing any event. 2365c8e55f36STejun Heo */ 2366c8e55f36STejun Heo worker_enter_idle(worker); 2367c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 23688b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 23691da177e4SLinus Torvalds schedule(); 2370c8e55f36STejun Heo goto woke_up; 23711da177e4SLinus Torvalds } 23721da177e4SLinus Torvalds 2373e22bee78STejun Heo /** 2374e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2375e22bee78STejun Heo * @__wq: the associated workqueue 2376e22bee78STejun Heo * 2377e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2378e22bee78STejun Heo * workqueue which has WQ_RESCUER set. 2379e22bee78STejun Heo * 2380e22bee78STejun Heo * Regular work processing on a gcwq may block trying to create a new 2381e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2382e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2383e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2384e22bee78STejun Heo * the problem rescuer solves. 2385e22bee78STejun Heo * 2386e22bee78STejun Heo * When such condition is possible, the gcwq summons rescuers of all 2387e22bee78STejun Heo * workqueues which have works queued on the gcwq and let them process 2388e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2389e22bee78STejun Heo * 2390e22bee78STejun Heo * This should happen rarely. 2391e22bee78STejun Heo */ 2392e22bee78STejun Heo static int rescuer_thread(void *__wq) 2393e22bee78STejun Heo { 2394e22bee78STejun Heo struct workqueue_struct *wq = __wq; 2395e22bee78STejun Heo struct worker *rescuer = wq->rescuer; 2396e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 2397f3421797STejun Heo bool is_unbound = wq->flags & WQ_UNBOUND; 2398e22bee78STejun Heo unsigned int cpu; 2399e22bee78STejun Heo 2400e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2401e22bee78STejun Heo repeat: 2402e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 24031da177e4SLinus Torvalds 24041da177e4SLinus Torvalds if (kthread_should_stop()) 2405e22bee78STejun Heo return 0; 24061da177e4SLinus Torvalds 2407f3421797STejun Heo /* 2408f3421797STejun Heo * See whether any cpu is asking for help. Unbounded 2409f3421797STejun Heo * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. 2410f3421797STejun Heo */ 2411f2e005aaSTejun Heo for_each_mayday_cpu(cpu, wq->mayday_mask) { 2412f3421797STejun Heo unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 2413f3421797STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); 2414bd7bdd43STejun Heo struct worker_pool *pool = cwq->pool; 2415bd7bdd43STejun Heo struct global_cwq *gcwq = pool->gcwq; 2416e22bee78STejun Heo struct work_struct *work, *n; 2417e22bee78STejun Heo 2418e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2419f2e005aaSTejun Heo mayday_clear_cpu(cpu, wq->mayday_mask); 2420e22bee78STejun Heo 2421e22bee78STejun Heo /* migrate to the target cpu if possible */ 2422bd7bdd43STejun Heo rescuer->pool = pool; 2423e22bee78STejun Heo worker_maybe_bind_and_lock(rescuer); 2424e22bee78STejun Heo 2425e22bee78STejun Heo /* 2426e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2427e22bee78STejun Heo * process'em. 2428e22bee78STejun Heo */ 2429e22bee78STejun Heo BUG_ON(!list_empty(&rescuer->scheduled)); 2430bd7bdd43STejun Heo list_for_each_entry_safe(work, n, &pool->worklist, entry) 2431e22bee78STejun Heo if (get_work_cwq(work) == cwq) 2432e22bee78STejun Heo move_linked_works(work, scheduled, &n); 2433e22bee78STejun Heo 2434e22bee78STejun Heo process_scheduled_works(rescuer); 24357576958aSTejun Heo 24367576958aSTejun Heo /* 24377576958aSTejun Heo * Leave this gcwq. If keep_working() is %true, notify a 24387576958aSTejun Heo * regular worker; otherwise, we end up with 0 concurrency 24397576958aSTejun Heo * and stalling the execution. 24407576958aSTejun Heo */ 244163d95a91STejun Heo if (keep_working(pool)) 244263d95a91STejun Heo wake_up_worker(pool); 24437576958aSTejun Heo 2444e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 24451da177e4SLinus Torvalds } 24461da177e4SLinus Torvalds 2447e22bee78STejun Heo schedule(); 2448e22bee78STejun Heo goto repeat; 24491da177e4SLinus Torvalds } 24501da177e4SLinus Torvalds 2451fc2e4d70SOleg Nesterov struct wq_barrier { 2452fc2e4d70SOleg Nesterov struct work_struct work; 2453fc2e4d70SOleg Nesterov struct completion done; 2454fc2e4d70SOleg Nesterov }; 2455fc2e4d70SOleg Nesterov 2456fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2457fc2e4d70SOleg Nesterov { 2458fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2459fc2e4d70SOleg Nesterov complete(&barr->done); 2460fc2e4d70SOleg Nesterov } 2461fc2e4d70SOleg Nesterov 24624690c4abSTejun Heo /** 24634690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 24644690c4abSTejun Heo * @cwq: cwq to insert barrier into 24654690c4abSTejun Heo * @barr: wq_barrier to insert 2466affee4b2STejun Heo * @target: target work to attach @barr to 2467affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 24684690c4abSTejun Heo * 2469affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2470affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2471affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2472affee4b2STejun Heo * cpu. 2473affee4b2STejun Heo * 2474affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2475affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2476affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2477affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2478affee4b2STejun Heo * after a work with LINKED flag set. 2479affee4b2STejun Heo * 2480affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2481affee4b2STejun Heo * underneath us, so we can't reliably determine cwq from @target. 24824690c4abSTejun Heo * 24834690c4abSTejun Heo * CONTEXT: 24848b03ae3cSTejun Heo * spin_lock_irq(gcwq->lock). 24854690c4abSTejun Heo */ 248683c22520SOleg Nesterov static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 2487affee4b2STejun Heo struct wq_barrier *barr, 2488affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2489fc2e4d70SOleg Nesterov { 2490affee4b2STejun Heo struct list_head *head; 2491affee4b2STejun Heo unsigned int linked = 0; 2492affee4b2STejun Heo 2493dc186ad7SThomas Gleixner /* 24948b03ae3cSTejun Heo * debugobject calls are safe here even with gcwq->lock locked 2495dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2496dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2497dc186ad7SThomas Gleixner * might deadlock. 2498dc186ad7SThomas Gleixner */ 2499ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 250022df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2501fc2e4d70SOleg Nesterov init_completion(&barr->done); 250283c22520SOleg Nesterov 2503affee4b2STejun Heo /* 2504affee4b2STejun Heo * If @target is currently being executed, schedule the 2505affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2506affee4b2STejun Heo */ 2507affee4b2STejun Heo if (worker) 2508affee4b2STejun Heo head = worker->scheduled.next; 2509affee4b2STejun Heo else { 2510affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2511affee4b2STejun Heo 2512affee4b2STejun Heo head = target->entry.next; 2513affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2514affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2515affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2516affee4b2STejun Heo } 2517affee4b2STejun Heo 2518dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2519affee4b2STejun Heo insert_work(cwq, &barr->work, head, 2520affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2521fc2e4d70SOleg Nesterov } 2522fc2e4d70SOleg Nesterov 252373f53c4aSTejun Heo /** 252473f53c4aSTejun Heo * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing 252573f53c4aSTejun Heo * @wq: workqueue being flushed 252673f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 252773f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 252873f53c4aSTejun Heo * 252973f53c4aSTejun Heo * Prepare cwqs for workqueue flushing. 253073f53c4aSTejun Heo * 253173f53c4aSTejun Heo * If @flush_color is non-negative, flush_color on all cwqs should be 253273f53c4aSTejun Heo * -1. If no cwq has in-flight commands at the specified color, all 253373f53c4aSTejun Heo * cwq->flush_color's stay at -1 and %false is returned. If any cwq 253473f53c4aSTejun Heo * has in flight commands, its cwq->flush_color is set to 253573f53c4aSTejun Heo * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq 253673f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 253773f53c4aSTejun Heo * 253873f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 253973f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 254073f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 254173f53c4aSTejun Heo * is returned. 254273f53c4aSTejun Heo * 254373f53c4aSTejun Heo * If @work_color is non-negative, all cwqs should have the same 254473f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 254573f53c4aSTejun Heo * advanced to @work_color. 254673f53c4aSTejun Heo * 254773f53c4aSTejun Heo * CONTEXT: 254873f53c4aSTejun Heo * mutex_lock(wq->flush_mutex). 254973f53c4aSTejun Heo * 255073f53c4aSTejun Heo * RETURNS: 255173f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 255273f53c4aSTejun Heo * otherwise. 255373f53c4aSTejun Heo */ 255473f53c4aSTejun Heo static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, 255573f53c4aSTejun Heo int flush_color, int work_color) 25561da177e4SLinus Torvalds { 255773f53c4aSTejun Heo bool wait = false; 255873f53c4aSTejun Heo unsigned int cpu; 25591da177e4SLinus Torvalds 256073f53c4aSTejun Heo if (flush_color >= 0) { 256173f53c4aSTejun Heo BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); 256273f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 1); 2563dc186ad7SThomas Gleixner } 256414441960SOleg Nesterov 2565f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 256673f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2567bd7bdd43STejun Heo struct global_cwq *gcwq = cwq->pool->gcwq; 25681da177e4SLinus Torvalds 25698b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 257073f53c4aSTejun Heo 257173f53c4aSTejun Heo if (flush_color >= 0) { 257273f53c4aSTejun Heo BUG_ON(cwq->flush_color != -1); 257373f53c4aSTejun Heo 257473f53c4aSTejun Heo if (cwq->nr_in_flight[flush_color]) { 257573f53c4aSTejun Heo cwq->flush_color = flush_color; 257673f53c4aSTejun Heo atomic_inc(&wq->nr_cwqs_to_flush); 257773f53c4aSTejun Heo wait = true; 25781da177e4SLinus Torvalds } 257973f53c4aSTejun Heo } 258073f53c4aSTejun Heo 258173f53c4aSTejun Heo if (work_color >= 0) { 258273f53c4aSTejun Heo BUG_ON(work_color != work_next_color(cwq->work_color)); 258373f53c4aSTejun Heo cwq->work_color = work_color; 258473f53c4aSTejun Heo } 258573f53c4aSTejun Heo 25868b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 25871da177e4SLinus Torvalds } 25881da177e4SLinus Torvalds 258973f53c4aSTejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) 259073f53c4aSTejun Heo complete(&wq->first_flusher->done); 259173f53c4aSTejun Heo 259273f53c4aSTejun Heo return wait; 259383c22520SOleg Nesterov } 25941da177e4SLinus Torvalds 25950fcb78c2SRolf Eike Beer /** 25961da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 25970fcb78c2SRolf Eike Beer * @wq: workqueue to flush 25981da177e4SLinus Torvalds * 25991da177e4SLinus Torvalds * Forces execution of the workqueue and blocks until its completion. 26001da177e4SLinus Torvalds * This is typically used in driver shutdown handlers. 26011da177e4SLinus Torvalds * 2602fc2e4d70SOleg Nesterov * We sleep until all works which were queued on entry have been handled, 2603fc2e4d70SOleg Nesterov * but we are not livelocked by new incoming ones. 26041da177e4SLinus Torvalds */ 26057ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 26061da177e4SLinus Torvalds { 260773f53c4aSTejun Heo struct wq_flusher this_flusher = { 260873f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 260973f53c4aSTejun Heo .flush_color = -1, 261073f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 261173f53c4aSTejun Heo }; 261273f53c4aSTejun Heo int next_color; 2613b1f4ec17SOleg Nesterov 26143295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 26153295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 261673f53c4aSTejun Heo 261773f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 261873f53c4aSTejun Heo 261973f53c4aSTejun Heo /* 262073f53c4aSTejun Heo * Start-to-wait phase 262173f53c4aSTejun Heo */ 262273f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 262373f53c4aSTejun Heo 262473f53c4aSTejun Heo if (next_color != wq->flush_color) { 262573f53c4aSTejun Heo /* 262673f53c4aSTejun Heo * Color space is not full. The current work_color 262773f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 262873f53c4aSTejun Heo * by one. 262973f53c4aSTejun Heo */ 263073f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow)); 263173f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 263273f53c4aSTejun Heo wq->work_color = next_color; 263373f53c4aSTejun Heo 263473f53c4aSTejun Heo if (!wq->first_flusher) { 263573f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 263673f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 263773f53c4aSTejun Heo 263873f53c4aSTejun Heo wq->first_flusher = &this_flusher; 263973f53c4aSTejun Heo 264073f53c4aSTejun Heo if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, 264173f53c4aSTejun Heo wq->work_color)) { 264273f53c4aSTejun Heo /* nothing to flush, done */ 264373f53c4aSTejun Heo wq->flush_color = next_color; 264473f53c4aSTejun Heo wq->first_flusher = NULL; 264573f53c4aSTejun Heo goto out_unlock; 264673f53c4aSTejun Heo } 264773f53c4aSTejun Heo } else { 264873f53c4aSTejun Heo /* wait in queue */ 264973f53c4aSTejun Heo BUG_ON(wq->flush_color == this_flusher.flush_color); 265073f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 265173f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 265273f53c4aSTejun Heo } 265373f53c4aSTejun Heo } else { 265473f53c4aSTejun Heo /* 265573f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 265673f53c4aSTejun Heo * The next flush completion will assign us 265773f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 265873f53c4aSTejun Heo */ 265973f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 266073f53c4aSTejun Heo } 266173f53c4aSTejun Heo 266273f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 266373f53c4aSTejun Heo 266473f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 266573f53c4aSTejun Heo 266673f53c4aSTejun Heo /* 266773f53c4aSTejun Heo * Wake-up-and-cascade phase 266873f53c4aSTejun Heo * 266973f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 267073f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 267173f53c4aSTejun Heo */ 267273f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 267373f53c4aSTejun Heo return; 267473f53c4aSTejun Heo 267573f53c4aSTejun Heo mutex_lock(&wq->flush_mutex); 267673f53c4aSTejun Heo 26774ce48b37STejun Heo /* we might have raced, check again with mutex held */ 26784ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 26794ce48b37STejun Heo goto out_unlock; 26804ce48b37STejun Heo 268173f53c4aSTejun Heo wq->first_flusher = NULL; 268273f53c4aSTejun Heo 268373f53c4aSTejun Heo BUG_ON(!list_empty(&this_flusher.list)); 268473f53c4aSTejun Heo BUG_ON(wq->flush_color != this_flusher.flush_color); 268573f53c4aSTejun Heo 268673f53c4aSTejun Heo while (true) { 268773f53c4aSTejun Heo struct wq_flusher *next, *tmp; 268873f53c4aSTejun Heo 268973f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 269073f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 269173f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 269273f53c4aSTejun Heo break; 269373f53c4aSTejun Heo list_del_init(&next->list); 269473f53c4aSTejun Heo complete(&next->done); 269573f53c4aSTejun Heo } 269673f53c4aSTejun Heo 269773f53c4aSTejun Heo BUG_ON(!list_empty(&wq->flusher_overflow) && 269873f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 269973f53c4aSTejun Heo 270073f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 270173f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 270273f53c4aSTejun Heo 270373f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 270473f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 270573f53c4aSTejun Heo /* 270673f53c4aSTejun Heo * Assign the same color to all overflowed 270773f53c4aSTejun Heo * flushers, advance work_color and append to 270873f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 270973f53c4aSTejun Heo * phase for these overflowed flushers. 271073f53c4aSTejun Heo */ 271173f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 271273f53c4aSTejun Heo tmp->flush_color = wq->work_color; 271373f53c4aSTejun Heo 271473f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 271573f53c4aSTejun Heo 271673f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 271773f53c4aSTejun Heo &wq->flusher_queue); 271873f53c4aSTejun Heo flush_workqueue_prep_cwqs(wq, -1, wq->work_color); 271973f53c4aSTejun Heo } 272073f53c4aSTejun Heo 272173f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 272273f53c4aSTejun Heo BUG_ON(wq->flush_color != wq->work_color); 272373f53c4aSTejun Heo break; 272473f53c4aSTejun Heo } 272573f53c4aSTejun Heo 272673f53c4aSTejun Heo /* 272773f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 272873f53c4aSTejun Heo * the new first flusher and arm cwqs. 272973f53c4aSTejun Heo */ 273073f53c4aSTejun Heo BUG_ON(wq->flush_color == wq->work_color); 273173f53c4aSTejun Heo BUG_ON(wq->flush_color != next->flush_color); 273273f53c4aSTejun Heo 273373f53c4aSTejun Heo list_del_init(&next->list); 273473f53c4aSTejun Heo wq->first_flusher = next; 273573f53c4aSTejun Heo 273673f53c4aSTejun Heo if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) 273773f53c4aSTejun Heo break; 273873f53c4aSTejun Heo 273973f53c4aSTejun Heo /* 274073f53c4aSTejun Heo * Meh... this color is already done, clear first 274173f53c4aSTejun Heo * flusher and repeat cascading. 274273f53c4aSTejun Heo */ 274373f53c4aSTejun Heo wq->first_flusher = NULL; 274473f53c4aSTejun Heo } 274573f53c4aSTejun Heo 274673f53c4aSTejun Heo out_unlock: 274773f53c4aSTejun Heo mutex_unlock(&wq->flush_mutex); 27481da177e4SLinus Torvalds } 2749ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 27501da177e4SLinus Torvalds 27519c5a2ba7STejun Heo /** 27529c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 27539c5a2ba7STejun Heo * @wq: workqueue to drain 27549c5a2ba7STejun Heo * 27559c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 27569c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 27579c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 27589c5a2ba7STejun Heo * repeatedly until it becomes empty. The number of flushing is detemined 27599c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 27609c5a2ba7STejun Heo * takes too long. 27619c5a2ba7STejun Heo */ 27629c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 27639c5a2ba7STejun Heo { 27649c5a2ba7STejun Heo unsigned int flush_cnt = 0; 27659c5a2ba7STejun Heo unsigned int cpu; 27669c5a2ba7STejun Heo 27679c5a2ba7STejun Heo /* 27689c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 27699c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 27709c5a2ba7STejun Heo * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. 27719c5a2ba7STejun Heo */ 27729c5a2ba7STejun Heo spin_lock(&workqueue_lock); 27739c5a2ba7STejun Heo if (!wq->nr_drainers++) 27749c5a2ba7STejun Heo wq->flags |= WQ_DRAINING; 27759c5a2ba7STejun Heo spin_unlock(&workqueue_lock); 27769c5a2ba7STejun Heo reflush: 27779c5a2ba7STejun Heo flush_workqueue(wq); 27789c5a2ba7STejun Heo 27799c5a2ba7STejun Heo for_each_cwq_cpu(cpu, wq) { 27809c5a2ba7STejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2781fa2563e4SThomas Tuttle bool drained; 27829c5a2ba7STejun Heo 2783bd7bdd43STejun Heo spin_lock_irq(&cwq->pool->gcwq->lock); 2784fa2563e4SThomas Tuttle drained = !cwq->nr_active && list_empty(&cwq->delayed_works); 2785bd7bdd43STejun Heo spin_unlock_irq(&cwq->pool->gcwq->lock); 2786fa2563e4SThomas Tuttle 2787fa2563e4SThomas Tuttle if (drained) 27889c5a2ba7STejun Heo continue; 27899c5a2ba7STejun Heo 27909c5a2ba7STejun Heo if (++flush_cnt == 10 || 27919c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 2792044c782cSValentin Ilie pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n", 27939c5a2ba7STejun Heo wq->name, flush_cnt); 27949c5a2ba7STejun Heo goto reflush; 27959c5a2ba7STejun Heo } 27969c5a2ba7STejun Heo 27979c5a2ba7STejun Heo spin_lock(&workqueue_lock); 27989c5a2ba7STejun Heo if (!--wq->nr_drainers) 27999c5a2ba7STejun Heo wq->flags &= ~WQ_DRAINING; 28009c5a2ba7STejun Heo spin_unlock(&workqueue_lock); 28019c5a2ba7STejun Heo } 28029c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 28039c5a2ba7STejun Heo 2804606a5020STejun Heo static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) 2805baf59022STejun Heo { 2806baf59022STejun Heo struct worker *worker = NULL; 2807baf59022STejun Heo struct global_cwq *gcwq; 2808baf59022STejun Heo struct cpu_workqueue_struct *cwq; 2809baf59022STejun Heo 2810baf59022STejun Heo might_sleep(); 2811baf59022STejun Heo gcwq = get_work_gcwq(work); 2812baf59022STejun Heo if (!gcwq) 2813baf59022STejun Heo return false; 2814baf59022STejun Heo 2815baf59022STejun Heo spin_lock_irq(&gcwq->lock); 2816baf59022STejun Heo if (!list_empty(&work->entry)) { 2817baf59022STejun Heo /* 2818baf59022STejun Heo * See the comment near try_to_grab_pending()->smp_rmb(). 2819baf59022STejun Heo * If it was re-queued to a different gcwq under us, we 2820baf59022STejun Heo * are not going to wait. 2821baf59022STejun Heo */ 2822baf59022STejun Heo smp_rmb(); 2823baf59022STejun Heo cwq = get_work_cwq(work); 2824bd7bdd43STejun Heo if (unlikely(!cwq || gcwq != cwq->pool->gcwq)) 2825baf59022STejun Heo goto already_gone; 2826606a5020STejun Heo } else { 2827baf59022STejun Heo worker = find_worker_executing_work(gcwq, work); 2828baf59022STejun Heo if (!worker) 2829baf59022STejun Heo goto already_gone; 2830baf59022STejun Heo cwq = worker->current_cwq; 2831606a5020STejun Heo } 2832baf59022STejun Heo 2833baf59022STejun Heo insert_wq_barrier(cwq, barr, work, worker); 2834baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2835baf59022STejun Heo 2836e159489bSTejun Heo /* 2837e159489bSTejun Heo * If @max_active is 1 or rescuer is in use, flushing another work 2838e159489bSTejun Heo * item on the same workqueue may lead to deadlock. Make sure the 2839e159489bSTejun Heo * flusher is not running on the same workqueue by verifying write 2840e159489bSTejun Heo * access. 2841e159489bSTejun Heo */ 2842e159489bSTejun Heo if (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER) 2843baf59022STejun Heo lock_map_acquire(&cwq->wq->lockdep_map); 2844e159489bSTejun Heo else 2845e159489bSTejun Heo lock_map_acquire_read(&cwq->wq->lockdep_map); 2846baf59022STejun Heo lock_map_release(&cwq->wq->lockdep_map); 2847e159489bSTejun Heo 2848baf59022STejun Heo return true; 2849baf59022STejun Heo already_gone: 2850baf59022STejun Heo spin_unlock_irq(&gcwq->lock); 2851baf59022STejun Heo return false; 2852baf59022STejun Heo } 2853baf59022STejun Heo 2854db700897SOleg Nesterov /** 2855401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 2856401a8d04STejun Heo * @work: the work to flush 2857db700897SOleg Nesterov * 2858606a5020STejun Heo * Wait until @work has finished execution. @work is guaranteed to be idle 2859606a5020STejun Heo * on return if it hasn't been requeued since flush started. 2860401a8d04STejun Heo * 2861401a8d04STejun Heo * RETURNS: 2862401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2863401a8d04STejun Heo * %false if it was already idle. 2864db700897SOleg Nesterov */ 2865401a8d04STejun Heo bool flush_work(struct work_struct *work) 2866db700897SOleg Nesterov { 2867db700897SOleg Nesterov struct wq_barrier barr; 2868db700897SOleg Nesterov 28690976dfc1SStephen Boyd lock_map_acquire(&work->lockdep_map); 28700976dfc1SStephen Boyd lock_map_release(&work->lockdep_map); 28710976dfc1SStephen Boyd 2872606a5020STejun Heo if (start_flush_work(work, &barr)) { 2873db700897SOleg Nesterov wait_for_completion(&barr.done); 2874dc186ad7SThomas Gleixner destroy_work_on_stack(&barr.work); 2875401a8d04STejun Heo return true; 2876606a5020STejun Heo } else { 2877401a8d04STejun Heo return false; 2878db700897SOleg Nesterov } 2879606a5020STejun Heo } 2880db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2881db700897SOleg Nesterov 288236e227d2STejun Heo static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 28831f1f642eSOleg Nesterov { 2884bbb68dfaSTejun Heo unsigned long flags; 28851f1f642eSOleg Nesterov int ret; 28861f1f642eSOleg Nesterov 28871f1f642eSOleg Nesterov do { 2888bbb68dfaSTejun Heo ret = try_to_grab_pending(work, is_dwork, &flags); 2889bbb68dfaSTejun Heo /* 2890bbb68dfaSTejun Heo * If someone else is canceling, wait for the same event it 2891bbb68dfaSTejun Heo * would be waiting for before retrying. 2892bbb68dfaSTejun Heo */ 2893bbb68dfaSTejun Heo if (unlikely(ret == -ENOENT)) 2894606a5020STejun Heo flush_work(work); 28951f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 28961f1f642eSOleg Nesterov 2897bbb68dfaSTejun Heo /* tell other tasks trying to grab @work to back off */ 2898bbb68dfaSTejun Heo mark_work_canceling(work); 2899bbb68dfaSTejun Heo local_irq_restore(flags); 2900bbb68dfaSTejun Heo 2901606a5020STejun Heo flush_work(work); 29027a22ad75STejun Heo clear_work_data(work); 29031f1f642eSOleg Nesterov return ret; 29041f1f642eSOleg Nesterov } 29051f1f642eSOleg Nesterov 29066e84d644SOleg Nesterov /** 2907401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 2908401a8d04STejun Heo * @work: the work to cancel 29096e84d644SOleg Nesterov * 2910401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 2911401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 2912401a8d04STejun Heo * another workqueue. On return from this function, @work is 2913401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 29141f1f642eSOleg Nesterov * 2915401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 2916401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 29176e84d644SOleg Nesterov * 2918401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 29196e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 2920401a8d04STejun Heo * 2921401a8d04STejun Heo * RETURNS: 2922401a8d04STejun Heo * %true if @work was pending, %false otherwise. 29236e84d644SOleg Nesterov */ 2924401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 29256e84d644SOleg Nesterov { 292636e227d2STejun Heo return __cancel_work_timer(work, false); 2927b89deed3SOleg Nesterov } 292828e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2929b89deed3SOleg Nesterov 29306e84d644SOleg Nesterov /** 2931401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 2932401a8d04STejun Heo * @dwork: the delayed work to flush 29336e84d644SOleg Nesterov * 2934401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 2935401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 2936401a8d04STejun Heo * considers the last queueing instance of @dwork. 29371f1f642eSOleg Nesterov * 2938401a8d04STejun Heo * RETURNS: 2939401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2940401a8d04STejun Heo * %false if it was already idle. 29416e84d644SOleg Nesterov */ 2942401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 2943401a8d04STejun Heo { 29448930cabaSTejun Heo local_irq_disable(); 2945401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 29461265057fSTejun Heo __queue_work(dwork->cpu, 2947401a8d04STejun Heo get_work_cwq(&dwork->work)->wq, &dwork->work); 29488930cabaSTejun Heo local_irq_enable(); 2949401a8d04STejun Heo return flush_work(&dwork->work); 2950401a8d04STejun Heo } 2951401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 2952401a8d04STejun Heo 2953401a8d04STejun Heo /** 2954401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 2955401a8d04STejun Heo * @dwork: the delayed work cancel 2956401a8d04STejun Heo * 2957401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 2958401a8d04STejun Heo * 2959401a8d04STejun Heo * RETURNS: 2960401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 2961401a8d04STejun Heo */ 2962401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 29636e84d644SOleg Nesterov { 296436e227d2STejun Heo return __cancel_work_timer(&dwork->work, true); 29656e84d644SOleg Nesterov } 2966f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 29671da177e4SLinus Torvalds 2968d4283e93STejun Heo /** 29690a13c00eSTejun Heo * schedule_work_on - put work task on a specific cpu 29700a13c00eSTejun Heo * @cpu: cpu to put the work task on 29710a13c00eSTejun Heo * @work: job to be done 29720a13c00eSTejun Heo * 29730a13c00eSTejun Heo * This puts a job on a specific cpu 29740a13c00eSTejun Heo */ 2975d4283e93STejun Heo bool schedule_work_on(int cpu, struct work_struct *work) 29760a13c00eSTejun Heo { 29770a13c00eSTejun Heo return queue_work_on(cpu, system_wq, work); 29780a13c00eSTejun Heo } 29790a13c00eSTejun Heo EXPORT_SYMBOL(schedule_work_on); 29800a13c00eSTejun Heo 29810fcb78c2SRolf Eike Beer /** 29820fcb78c2SRolf Eike Beer * schedule_work - put work task in global workqueue 29830fcb78c2SRolf Eike Beer * @work: job to be done 29840fcb78c2SRolf Eike Beer * 2985d4283e93STejun Heo * Returns %false if @work was already on the kernel-global workqueue and 2986d4283e93STejun Heo * %true otherwise. 29875b0f437dSBart Van Assche * 29885b0f437dSBart Van Assche * This puts a job in the kernel-global workqueue if it was not already 29895b0f437dSBart Van Assche * queued and leaves it in the same position on the kernel-global 29905b0f437dSBart Van Assche * workqueue otherwise. 29910fcb78c2SRolf Eike Beer */ 2992d4283e93STejun Heo bool schedule_work(struct work_struct *work) 29931da177e4SLinus Torvalds { 2994d320c038STejun Heo return queue_work(system_wq, work); 29951da177e4SLinus Torvalds } 2996ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_work); 29971da177e4SLinus Torvalds 29980fcb78c2SRolf Eike Beer /** 29990fcb78c2SRolf Eike Beer * schedule_delayed_work_on - queue work in global workqueue on CPU after delay 30000fcb78c2SRolf Eike Beer * @cpu: cpu to use 300152bad64dSDavid Howells * @dwork: job to be done 30020fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait 30030fcb78c2SRolf Eike Beer * 30040fcb78c2SRolf Eike Beer * After waiting for a given time this puts a job in the kernel-global 30050fcb78c2SRolf Eike Beer * workqueue on the specified CPU. 30060fcb78c2SRolf Eike Beer */ 3007d4283e93STejun Heo bool schedule_delayed_work_on(int cpu, struct delayed_work *dwork, 3008d4283e93STejun Heo unsigned long delay) 30091da177e4SLinus Torvalds { 3010d320c038STejun Heo return queue_delayed_work_on(cpu, system_wq, dwork, delay); 30111da177e4SLinus Torvalds } 3012ae90dd5dSDave Jones EXPORT_SYMBOL(schedule_delayed_work_on); 30131da177e4SLinus Torvalds 3014b6136773SAndrew Morton /** 30150a13c00eSTejun Heo * schedule_delayed_work - put work task in global workqueue after delay 30160a13c00eSTejun Heo * @dwork: job to be done 30170a13c00eSTejun Heo * @delay: number of jiffies to wait or 0 for immediate execution 30180a13c00eSTejun Heo * 30190a13c00eSTejun Heo * After waiting for a given time this puts a job in the kernel-global 30200a13c00eSTejun Heo * workqueue. 30210a13c00eSTejun Heo */ 3022d4283e93STejun Heo bool schedule_delayed_work(struct delayed_work *dwork, unsigned long delay) 30230a13c00eSTejun Heo { 30240a13c00eSTejun Heo return queue_delayed_work(system_wq, dwork, delay); 30250a13c00eSTejun Heo } 30260a13c00eSTejun Heo EXPORT_SYMBOL(schedule_delayed_work); 30270a13c00eSTejun Heo 30280a13c00eSTejun Heo /** 302931ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 3030b6136773SAndrew Morton * @func: the function to call 3031b6136773SAndrew Morton * 303231ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 303331ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 3034b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 303531ddd871STejun Heo * 303631ddd871STejun Heo * RETURNS: 303731ddd871STejun Heo * 0 on success, -errno on failure. 3038b6136773SAndrew Morton */ 303965f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 304015316ba8SChristoph Lameter { 304115316ba8SChristoph Lameter int cpu; 304238f51568SNamhyung Kim struct work_struct __percpu *works; 304315316ba8SChristoph Lameter 3044b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 3045b6136773SAndrew Morton if (!works) 304615316ba8SChristoph Lameter return -ENOMEM; 3047b6136773SAndrew Morton 304895402b38SGautham R Shenoy get_online_cpus(); 304993981800STejun Heo 305015316ba8SChristoph Lameter for_each_online_cpu(cpu) { 30519bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 30529bfb1839SIngo Molnar 30539bfb1839SIngo Molnar INIT_WORK(work, func); 30548de6d308SOleg Nesterov schedule_work_on(cpu, work); 305515316ba8SChristoph Lameter } 305693981800STejun Heo 305793981800STejun Heo for_each_online_cpu(cpu) 30588616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 305993981800STejun Heo 306095402b38SGautham R Shenoy put_online_cpus(); 3061b6136773SAndrew Morton free_percpu(works); 306215316ba8SChristoph Lameter return 0; 306315316ba8SChristoph Lameter } 306415316ba8SChristoph Lameter 3065eef6a7d5SAlan Stern /** 3066eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 3067eef6a7d5SAlan Stern * 3068eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 3069eef6a7d5SAlan Stern * completion. 3070eef6a7d5SAlan Stern * 3071eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 3072eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 3073eef6a7d5SAlan Stern * will lead to deadlock: 3074eef6a7d5SAlan Stern * 3075eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 3076eef6a7d5SAlan Stern * a lock held by your code or its caller. 3077eef6a7d5SAlan Stern * 3078eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 3079eef6a7d5SAlan Stern * 3080eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 3081eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 3082eef6a7d5SAlan Stern * what locks they need, which you have no control over. 3083eef6a7d5SAlan Stern * 3084eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 3085eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 3086eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 3087eef6a7d5SAlan Stern * cancel_work_sync() instead. 3088eef6a7d5SAlan Stern */ 30891da177e4SLinus Torvalds void flush_scheduled_work(void) 30901da177e4SLinus Torvalds { 3091d320c038STejun Heo flush_workqueue(system_wq); 30921da177e4SLinus Torvalds } 3093ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 30941da177e4SLinus Torvalds 30951da177e4SLinus Torvalds /** 30961fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 30971fa44ecaSJames Bottomley * @fn: the function to execute 30981fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 30991fa44ecaSJames Bottomley * be available when the work executes) 31001fa44ecaSJames Bottomley * 31011fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 31021fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 31031fa44ecaSJames Bottomley * 31041fa44ecaSJames Bottomley * Returns: 0 - function was executed 31051fa44ecaSJames Bottomley * 1 - function was scheduled for execution 31061fa44ecaSJames Bottomley */ 310765f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 31081fa44ecaSJames Bottomley { 31091fa44ecaSJames Bottomley if (!in_interrupt()) { 311065f27f38SDavid Howells fn(&ew->work); 31111fa44ecaSJames Bottomley return 0; 31121fa44ecaSJames Bottomley } 31131fa44ecaSJames Bottomley 311465f27f38SDavid Howells INIT_WORK(&ew->work, fn); 31151fa44ecaSJames Bottomley schedule_work(&ew->work); 31161fa44ecaSJames Bottomley 31171fa44ecaSJames Bottomley return 1; 31181fa44ecaSJames Bottomley } 31191fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 31201fa44ecaSJames Bottomley 31211da177e4SLinus Torvalds int keventd_up(void) 31221da177e4SLinus Torvalds { 3123d320c038STejun Heo return system_wq != NULL; 31241da177e4SLinus Torvalds } 31251da177e4SLinus Torvalds 3126bdbc5dd7STejun Heo static int alloc_cwqs(struct workqueue_struct *wq) 31271da177e4SLinus Torvalds { 31283af24433SOleg Nesterov /* 31290f900049STejun Heo * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. 31300f900049STejun Heo * Make sure that the alignment isn't lower than that of 31310f900049STejun Heo * unsigned long long. 31323af24433SOleg Nesterov */ 31330f900049STejun Heo const size_t size = sizeof(struct cpu_workqueue_struct); 31340f900049STejun Heo const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, 31350f900049STejun Heo __alignof__(unsigned long long)); 31363af24433SOleg Nesterov 3137e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 3138f3421797STejun Heo wq->cpu_wq.pcpu = __alloc_percpu(size, align); 3139931ac77eSTejun Heo else { 31400f900049STejun Heo void *ptr; 3141e1d8aa9fSFrederic Weisbecker 31420f900049STejun Heo /* 3143f3421797STejun Heo * Allocate enough room to align cwq and put an extra 3144f3421797STejun Heo * pointer at the end pointing back to the originally 3145f3421797STejun Heo * allocated pointer which will be used for free. 31460f900049STejun Heo */ 3147bdbc5dd7STejun Heo ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); 3148bdbc5dd7STejun Heo if (ptr) { 3149bdbc5dd7STejun Heo wq->cpu_wq.single = PTR_ALIGN(ptr, align); 3150bdbc5dd7STejun Heo *(void **)(wq->cpu_wq.single + 1) = ptr; 3151bdbc5dd7STejun Heo } 31523af24433SOleg Nesterov } 31533af24433SOleg Nesterov 31540415b00dSTejun Heo /* just in case, make sure it's actually aligned */ 3155bdbc5dd7STejun Heo BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); 3156bdbc5dd7STejun Heo return wq->cpu_wq.v ? 0 : -ENOMEM; 31570f900049STejun Heo } 31580f900049STejun Heo 3159bdbc5dd7STejun Heo static void free_cwqs(struct workqueue_struct *wq) 316006ba38a9SOleg Nesterov { 3161e06ffa1eSLai Jiangshan if (!(wq->flags & WQ_UNBOUND)) 3162bdbc5dd7STejun Heo free_percpu(wq->cpu_wq.pcpu); 3163f3421797STejun Heo else if (wq->cpu_wq.single) { 3164f3421797STejun Heo /* the pointer to free is stored right after the cwq */ 3165f3421797STejun Heo kfree(*(void **)(wq->cpu_wq.single + 1)); 316606ba38a9SOleg Nesterov } 316706ba38a9SOleg Nesterov } 316806ba38a9SOleg Nesterov 3169f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 3170f3421797STejun Heo const char *name) 3171b71ab8c2STejun Heo { 3172f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 3173f3421797STejun Heo 3174f3421797STejun Heo if (max_active < 1 || max_active > lim) 3175044c782cSValentin Ilie pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 3176f3421797STejun Heo max_active, name, 1, lim); 3177b71ab8c2STejun Heo 3178f3421797STejun Heo return clamp_val(max_active, 1, lim); 3179b71ab8c2STejun Heo } 3180b71ab8c2STejun Heo 3181b196be89STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *fmt, 318297e37d7bSTejun Heo unsigned int flags, 31831e19ffc6STejun Heo int max_active, 3184eb13ba87SJohannes Berg struct lock_class_key *key, 3185b196be89STejun Heo const char *lock_name, ...) 31863af24433SOleg Nesterov { 3187b196be89STejun Heo va_list args, args1; 31883af24433SOleg Nesterov struct workqueue_struct *wq; 3189c34056a3STejun Heo unsigned int cpu; 3190b196be89STejun Heo size_t namelen; 3191b196be89STejun Heo 3192b196be89STejun Heo /* determine namelen, allocate wq and format name */ 3193b196be89STejun Heo va_start(args, lock_name); 3194b196be89STejun Heo va_copy(args1, args); 3195b196be89STejun Heo namelen = vsnprintf(NULL, 0, fmt, args) + 1; 3196b196be89STejun Heo 3197b196be89STejun Heo wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL); 3198b196be89STejun Heo if (!wq) 3199b196be89STejun Heo goto err; 3200b196be89STejun Heo 3201b196be89STejun Heo vsnprintf(wq->name, namelen, fmt, args1); 3202b196be89STejun Heo va_end(args); 3203b196be89STejun Heo va_end(args1); 32043af24433SOleg Nesterov 3205f3421797STejun Heo /* 32066370a6adSTejun Heo * Workqueues which may be used during memory reclaim should 32076370a6adSTejun Heo * have a rescuer to guarantee forward progress. 32086370a6adSTejun Heo */ 32096370a6adSTejun Heo if (flags & WQ_MEM_RECLAIM) 32106370a6adSTejun Heo flags |= WQ_RESCUER; 32116370a6adSTejun Heo 3212d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 3213b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 32143af24433SOleg Nesterov 3215b196be89STejun Heo /* init wq */ 321697e37d7bSTejun Heo wq->flags = flags; 3217a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 321873f53c4aSTejun Heo mutex_init(&wq->flush_mutex); 321973f53c4aSTejun Heo atomic_set(&wq->nr_cwqs_to_flush, 0); 322073f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 322173f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 32223af24433SOleg Nesterov 3223eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 3224cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 32253af24433SOleg Nesterov 3226bdbc5dd7STejun Heo if (alloc_cwqs(wq) < 0) 3227bdbc5dd7STejun Heo goto err; 3228bdbc5dd7STejun Heo 3229f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 32301537663fSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 32318b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 32323270476aSTejun Heo int pool_idx = (bool)(flags & WQ_HIGHPRI); 32331537663fSTejun Heo 32340f900049STejun Heo BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 32353270476aSTejun Heo cwq->pool = &gcwq->pools[pool_idx]; 3236c34056a3STejun Heo cwq->wq = wq; 323773f53c4aSTejun Heo cwq->flush_color = -1; 32381e19ffc6STejun Heo cwq->max_active = max_active; 32391e19ffc6STejun Heo INIT_LIST_HEAD(&cwq->delayed_works); 3240e22bee78STejun Heo } 32411537663fSTejun Heo 3242e22bee78STejun Heo if (flags & WQ_RESCUER) { 3243e22bee78STejun Heo struct worker *rescuer; 3244e22bee78STejun Heo 3245f2e005aaSTejun Heo if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) 3246e22bee78STejun Heo goto err; 3247e22bee78STejun Heo 3248e22bee78STejun Heo wq->rescuer = rescuer = alloc_worker(); 3249e22bee78STejun Heo if (!rescuer) 3250e22bee78STejun Heo goto err; 3251e22bee78STejun Heo 3252b196be89STejun Heo rescuer->task = kthread_create(rescuer_thread, wq, "%s", 3253b196be89STejun Heo wq->name); 3254e22bee78STejun Heo if (IS_ERR(rescuer->task)) 3255e22bee78STejun Heo goto err; 3256e22bee78STejun Heo 3257e22bee78STejun Heo rescuer->task->flags |= PF_THREAD_BOUND; 3258e22bee78STejun Heo wake_up_process(rescuer->task); 32593af24433SOleg Nesterov } 32601537663fSTejun Heo 32613af24433SOleg Nesterov /* 3262a0a1a5fdSTejun Heo * workqueue_lock protects global freeze state and workqueues 3263a0a1a5fdSTejun Heo * list. Grab it, set max_active accordingly and add the new 3264a0a1a5fdSTejun Heo * workqueue to workqueues list. 32653af24433SOleg Nesterov */ 32663af24433SOleg Nesterov spin_lock(&workqueue_lock); 3267a0a1a5fdSTejun Heo 326858a69cb4STejun Heo if (workqueue_freezing && wq->flags & WQ_FREEZABLE) 3269f3421797STejun Heo for_each_cwq_cpu(cpu, wq) 3270a0a1a5fdSTejun Heo get_cwq(cpu, wq)->max_active = 0; 3271a0a1a5fdSTejun Heo 32723af24433SOleg Nesterov list_add(&wq->list, &workqueues); 3273a0a1a5fdSTejun Heo 32743af24433SOleg Nesterov spin_unlock(&workqueue_lock); 32753af24433SOleg Nesterov 32763af24433SOleg Nesterov return wq; 32774690c4abSTejun Heo err: 32784690c4abSTejun Heo if (wq) { 3279bdbc5dd7STejun Heo free_cwqs(wq); 3280f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 3281e22bee78STejun Heo kfree(wq->rescuer); 32824690c4abSTejun Heo kfree(wq); 32833af24433SOleg Nesterov } 32844690c4abSTejun Heo return NULL; 32851da177e4SLinus Torvalds } 3286d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 32871da177e4SLinus Torvalds 32883af24433SOleg Nesterov /** 32893af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 32903af24433SOleg Nesterov * @wq: target workqueue 32913af24433SOleg Nesterov * 32923af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 32933af24433SOleg Nesterov */ 32943af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 32953af24433SOleg Nesterov { 3296c8e55f36STejun Heo unsigned int cpu; 32973af24433SOleg Nesterov 32989c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 32999c5a2ba7STejun Heo drain_workqueue(wq); 3300c8efcc25STejun Heo 3301a0a1a5fdSTejun Heo /* 3302a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 3303a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 3304a0a1a5fdSTejun Heo */ 330595402b38SGautham R Shenoy spin_lock(&workqueue_lock); 33063af24433SOleg Nesterov list_del(&wq->list); 330795402b38SGautham R Shenoy spin_unlock(&workqueue_lock); 33083af24433SOleg Nesterov 3309e22bee78STejun Heo /* sanity check */ 3310f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 331173f53c4aSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 331273f53c4aSTejun Heo int i; 33133af24433SOleg Nesterov 331473f53c4aSTejun Heo for (i = 0; i < WORK_NR_COLORS; i++) 331573f53c4aSTejun Heo BUG_ON(cwq->nr_in_flight[i]); 33161e19ffc6STejun Heo BUG_ON(cwq->nr_active); 33171e19ffc6STejun Heo BUG_ON(!list_empty(&cwq->delayed_works)); 331873f53c4aSTejun Heo } 33191537663fSTejun Heo 3320e22bee78STejun Heo if (wq->flags & WQ_RESCUER) { 3321e22bee78STejun Heo kthread_stop(wq->rescuer->task); 3322f2e005aaSTejun Heo free_mayday_mask(wq->mayday_mask); 33238d9df9f0SXiaotian Feng kfree(wq->rescuer); 3324e22bee78STejun Heo } 3325e22bee78STejun Heo 3326bdbc5dd7STejun Heo free_cwqs(wq); 33273af24433SOleg Nesterov kfree(wq); 33283af24433SOleg Nesterov } 33293af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 33303af24433SOleg Nesterov 3331dcd989cbSTejun Heo /** 3332dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 3333dcd989cbSTejun Heo * @wq: target workqueue 3334dcd989cbSTejun Heo * @max_active: new max_active value. 3335dcd989cbSTejun Heo * 3336dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 3337dcd989cbSTejun Heo * 3338dcd989cbSTejun Heo * CONTEXT: 3339dcd989cbSTejun Heo * Don't call from IRQ context. 3340dcd989cbSTejun Heo */ 3341dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 3342dcd989cbSTejun Heo { 3343dcd989cbSTejun Heo unsigned int cpu; 3344dcd989cbSTejun Heo 3345f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 3346dcd989cbSTejun Heo 3347dcd989cbSTejun Heo spin_lock(&workqueue_lock); 3348dcd989cbSTejun Heo 3349dcd989cbSTejun Heo wq->saved_max_active = max_active; 3350dcd989cbSTejun Heo 3351f3421797STejun Heo for_each_cwq_cpu(cpu, wq) { 3352dcd989cbSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3353dcd989cbSTejun Heo 3354dcd989cbSTejun Heo spin_lock_irq(&gcwq->lock); 3355dcd989cbSTejun Heo 335658a69cb4STejun Heo if (!(wq->flags & WQ_FREEZABLE) || 3357dcd989cbSTejun Heo !(gcwq->flags & GCWQ_FREEZING)) 3358dcd989cbSTejun Heo get_cwq(gcwq->cpu, wq)->max_active = max_active; 3359dcd989cbSTejun Heo 3360dcd989cbSTejun Heo spin_unlock_irq(&gcwq->lock); 3361dcd989cbSTejun Heo } 3362dcd989cbSTejun Heo 3363dcd989cbSTejun Heo spin_unlock(&workqueue_lock); 3364dcd989cbSTejun Heo } 3365dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 3366dcd989cbSTejun Heo 3367dcd989cbSTejun Heo /** 3368dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 3369dcd989cbSTejun Heo * @cpu: CPU in question 3370dcd989cbSTejun Heo * @wq: target workqueue 3371dcd989cbSTejun Heo * 3372dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 3373dcd989cbSTejun Heo * no synchronization around this function and the test result is 3374dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3375dcd989cbSTejun Heo * 3376dcd989cbSTejun Heo * RETURNS: 3377dcd989cbSTejun Heo * %true if congested, %false otherwise. 3378dcd989cbSTejun Heo */ 3379dcd989cbSTejun Heo bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) 3380dcd989cbSTejun Heo { 3381dcd989cbSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3382dcd989cbSTejun Heo 3383dcd989cbSTejun Heo return !list_empty(&cwq->delayed_works); 3384dcd989cbSTejun Heo } 3385dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 3386dcd989cbSTejun Heo 3387dcd989cbSTejun Heo /** 3388dcd989cbSTejun Heo * work_cpu - return the last known associated cpu for @work 3389dcd989cbSTejun Heo * @work: the work of interest 3390dcd989cbSTejun Heo * 3391dcd989cbSTejun Heo * RETURNS: 3392bdbc5dd7STejun Heo * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. 3393dcd989cbSTejun Heo */ 3394dcd989cbSTejun Heo unsigned int work_cpu(struct work_struct *work) 3395dcd989cbSTejun Heo { 3396dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3397dcd989cbSTejun Heo 3398bdbc5dd7STejun Heo return gcwq ? gcwq->cpu : WORK_CPU_NONE; 3399dcd989cbSTejun Heo } 3400dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_cpu); 3401dcd989cbSTejun Heo 3402dcd989cbSTejun Heo /** 3403dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 3404dcd989cbSTejun Heo * @work: the work to be tested 3405dcd989cbSTejun Heo * 3406dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 3407dcd989cbSTejun Heo * synchronization around this function and the test result is 3408dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 3409dcd989cbSTejun Heo * Especially for reentrant wqs, the pending state might hide the 3410dcd989cbSTejun Heo * running state. 3411dcd989cbSTejun Heo * 3412dcd989cbSTejun Heo * RETURNS: 3413dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 3414dcd989cbSTejun Heo */ 3415dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 3416dcd989cbSTejun Heo { 3417dcd989cbSTejun Heo struct global_cwq *gcwq = get_work_gcwq(work); 3418dcd989cbSTejun Heo unsigned long flags; 3419dcd989cbSTejun Heo unsigned int ret = 0; 3420dcd989cbSTejun Heo 3421dcd989cbSTejun Heo if (!gcwq) 3422dcd989cbSTejun Heo return false; 3423dcd989cbSTejun Heo 3424dcd989cbSTejun Heo spin_lock_irqsave(&gcwq->lock, flags); 3425dcd989cbSTejun Heo 3426dcd989cbSTejun Heo if (work_pending(work)) 3427dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 3428dcd989cbSTejun Heo if (find_worker_executing_work(gcwq, work)) 3429dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 3430dcd989cbSTejun Heo 3431dcd989cbSTejun Heo spin_unlock_irqrestore(&gcwq->lock, flags); 3432dcd989cbSTejun Heo 3433dcd989cbSTejun Heo return ret; 3434dcd989cbSTejun Heo } 3435dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 3436dcd989cbSTejun Heo 3437db7bccf4STejun Heo /* 3438db7bccf4STejun Heo * CPU hotplug. 3439db7bccf4STejun Heo * 3440e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 3441e22bee78STejun Heo * are a lot of assumptions on strong associations among work, cwq and 3442e22bee78STejun Heo * gcwq which make migrating pending and scheduled works very 3443e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 3444e22bee78STejun Heo * gcwqs serve mix of short, long and very long running works making 3445e22bee78STejun Heo * blocked draining impractical. 3446e22bee78STejun Heo * 3447628c78e7STejun Heo * This is solved by allowing a gcwq to be disassociated from the CPU 3448628c78e7STejun Heo * running as an unbound one and allowing it to be reattached later if the 3449628c78e7STejun Heo * cpu comes back online. 3450db7bccf4STejun Heo */ 3451db7bccf4STejun Heo 345260373152STejun Heo /* claim manager positions of all pools */ 34538db25e78STejun Heo static void gcwq_claim_management_and_lock(struct global_cwq *gcwq) 345460373152STejun Heo { 345560373152STejun Heo struct worker_pool *pool; 345660373152STejun Heo 345760373152STejun Heo for_each_worker_pool(pool, gcwq) 345860373152STejun Heo mutex_lock_nested(&pool->manager_mutex, pool - gcwq->pools); 34598db25e78STejun Heo spin_lock_irq(&gcwq->lock); 346060373152STejun Heo } 346160373152STejun Heo 346260373152STejun Heo /* release manager positions */ 34638db25e78STejun Heo static void gcwq_release_management_and_unlock(struct global_cwq *gcwq) 346460373152STejun Heo { 346560373152STejun Heo struct worker_pool *pool; 346660373152STejun Heo 34678db25e78STejun Heo spin_unlock_irq(&gcwq->lock); 346860373152STejun Heo for_each_worker_pool(pool, gcwq) 346960373152STejun Heo mutex_unlock(&pool->manager_mutex); 347060373152STejun Heo } 347160373152STejun Heo 3472628c78e7STejun Heo static void gcwq_unbind_fn(struct work_struct *work) 3473db7bccf4STejun Heo { 3474628c78e7STejun Heo struct global_cwq *gcwq = get_gcwq(smp_processor_id()); 34754ce62e9eSTejun Heo struct worker_pool *pool; 3476db7bccf4STejun Heo struct worker *worker; 3477db7bccf4STejun Heo struct hlist_node *pos; 3478db7bccf4STejun Heo int i; 3479db7bccf4STejun Heo 3480db7bccf4STejun Heo BUG_ON(gcwq->cpu != smp_processor_id()); 3481db7bccf4STejun Heo 34828db25e78STejun Heo gcwq_claim_management_and_lock(gcwq); 3483e22bee78STejun Heo 3484f2d5a0eeSTejun Heo /* 3485f2d5a0eeSTejun Heo * We've claimed all manager positions. Make all workers unbound 3486f2d5a0eeSTejun Heo * and set DISASSOCIATED. Before this, all workers except for the 3487f2d5a0eeSTejun Heo * ones which are still executing works from before the last CPU 3488f2d5a0eeSTejun Heo * down must be on the cpu. After this, they may become diasporas. 3489f2d5a0eeSTejun Heo */ 349060373152STejun Heo for_each_worker_pool(pool, gcwq) 34914ce62e9eSTejun Heo list_for_each_entry(worker, &pool->idle_list, entry) 3492403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 3493db7bccf4STejun Heo 3494db7bccf4STejun Heo for_each_busy_worker(worker, i, pos, gcwq) 3495403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 3496db7bccf4STejun Heo 3497f2d5a0eeSTejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 3498f2d5a0eeSTejun Heo 34998db25e78STejun Heo gcwq_release_management_and_unlock(gcwq); 3500e22bee78STejun Heo 3501e22bee78STejun Heo /* 3502628c78e7STejun Heo * Call schedule() so that we cross rq->lock and thus can guarantee 3503628c78e7STejun Heo * sched callbacks see the %WORKER_UNBOUND flag. This is necessary 3504628c78e7STejun Heo * as scheduler callbacks may be invoked from other cpus. 3505628c78e7STejun Heo */ 3506628c78e7STejun Heo schedule(); 3507628c78e7STejun Heo 3508628c78e7STejun Heo /* 3509628c78e7STejun Heo * Sched callbacks are disabled now. Zap nr_running. After this, 3510628c78e7STejun Heo * nr_running stays zero and need_more_worker() and keep_working() 3511628c78e7STejun Heo * are always true as long as the worklist is not empty. @gcwq now 3512628c78e7STejun Heo * behaves as unbound (in terms of concurrency management) gcwq 3513628c78e7STejun Heo * which is served by workers tied to the CPU. 3514628c78e7STejun Heo * 3515628c78e7STejun Heo * On return from this function, the current worker would trigger 3516628c78e7STejun Heo * unbound chain execution of pending work items if other workers 3517628c78e7STejun Heo * didn't already. 3518e22bee78STejun Heo */ 35194ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) 35204ce62e9eSTejun Heo atomic_set(get_pool_nr_running(pool), 0); 3521db7bccf4STejun Heo } 3522db7bccf4STejun Heo 35238db25e78STejun Heo /* 35248db25e78STejun Heo * Workqueues should be brought up before normal priority CPU notifiers. 35258db25e78STejun Heo * This will be registered high priority CPU notifier. 35268db25e78STejun Heo */ 35278db25e78STejun Heo static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb, 35281da177e4SLinus Torvalds unsigned long action, 35291da177e4SLinus Torvalds void *hcpu) 35301da177e4SLinus Torvalds { 35313af24433SOleg Nesterov unsigned int cpu = (unsigned long)hcpu; 3532db7bccf4STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 35334ce62e9eSTejun Heo struct worker_pool *pool; 35341da177e4SLinus Torvalds 35358db25e78STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 35363af24433SOleg Nesterov case CPU_UP_PREPARE: 35374ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) { 35383ce63377STejun Heo struct worker *worker; 35393ce63377STejun Heo 35403ce63377STejun Heo if (pool->nr_workers) 35413ce63377STejun Heo continue; 35423ce63377STejun Heo 35433ce63377STejun Heo worker = create_worker(pool); 35443ce63377STejun Heo if (!worker) 35453ce63377STejun Heo return NOTIFY_BAD; 35463ce63377STejun Heo 35473ce63377STejun Heo spin_lock_irq(&gcwq->lock); 35483ce63377STejun Heo start_worker(worker); 35493ce63377STejun Heo spin_unlock_irq(&gcwq->lock); 35503af24433SOleg Nesterov } 35511da177e4SLinus Torvalds break; 35521da177e4SLinus Torvalds 355365758202STejun Heo case CPU_DOWN_FAILED: 355465758202STejun Heo case CPU_ONLINE: 35558db25e78STejun Heo gcwq_claim_management_and_lock(gcwq); 35568db25e78STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 35578db25e78STejun Heo rebind_workers(gcwq); 35588db25e78STejun Heo gcwq_release_management_and_unlock(gcwq); 35598db25e78STejun Heo break; 356065758202STejun Heo } 356165758202STejun Heo return NOTIFY_OK; 356265758202STejun Heo } 356365758202STejun Heo 356465758202STejun Heo /* 356565758202STejun Heo * Workqueues should be brought down after normal priority CPU notifiers. 356665758202STejun Heo * This will be registered as low priority CPU notifier. 356765758202STejun Heo */ 356865758202STejun Heo static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb, 356965758202STejun Heo unsigned long action, 357065758202STejun Heo void *hcpu) 357165758202STejun Heo { 35728db25e78STejun Heo unsigned int cpu = (unsigned long)hcpu; 35738db25e78STejun Heo struct work_struct unbind_work; 35748db25e78STejun Heo 357565758202STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 357665758202STejun Heo case CPU_DOWN_PREPARE: 35778db25e78STejun Heo /* unbinding should happen on the local CPU */ 35788db25e78STejun Heo INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn); 35797635d2fdSJoonsoo Kim queue_work_on(cpu, system_highpri_wq, &unbind_work); 35808db25e78STejun Heo flush_work(&unbind_work); 35818db25e78STejun Heo break; 358265758202STejun Heo } 358365758202STejun Heo return NOTIFY_OK; 358465758202STejun Heo } 358565758202STejun Heo 35862d3854a3SRusty Russell #ifdef CONFIG_SMP 35878ccad40dSRusty Russell 35882d3854a3SRusty Russell struct work_for_cpu { 35896b44003eSAndrew Morton struct completion completion; 35902d3854a3SRusty Russell long (*fn)(void *); 35912d3854a3SRusty Russell void *arg; 35922d3854a3SRusty Russell long ret; 35932d3854a3SRusty Russell }; 35942d3854a3SRusty Russell 35956b44003eSAndrew Morton static int do_work_for_cpu(void *_wfc) 35962d3854a3SRusty Russell { 35976b44003eSAndrew Morton struct work_for_cpu *wfc = _wfc; 35982d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 35996b44003eSAndrew Morton complete(&wfc->completion); 36006b44003eSAndrew Morton return 0; 36012d3854a3SRusty Russell } 36022d3854a3SRusty Russell 36032d3854a3SRusty Russell /** 36042d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 36052d3854a3SRusty Russell * @cpu: the cpu to run on 36062d3854a3SRusty Russell * @fn: the function to run 36072d3854a3SRusty Russell * @arg: the function arg 36082d3854a3SRusty Russell * 360931ad9081SRusty Russell * This will return the value @fn returns. 361031ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 36116b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 36122d3854a3SRusty Russell */ 36132d3854a3SRusty Russell long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) 36142d3854a3SRusty Russell { 36156b44003eSAndrew Morton struct task_struct *sub_thread; 36166b44003eSAndrew Morton struct work_for_cpu wfc = { 36176b44003eSAndrew Morton .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), 36186b44003eSAndrew Morton .fn = fn, 36196b44003eSAndrew Morton .arg = arg, 36206b44003eSAndrew Morton }; 36212d3854a3SRusty Russell 36226b44003eSAndrew Morton sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); 36236b44003eSAndrew Morton if (IS_ERR(sub_thread)) 36246b44003eSAndrew Morton return PTR_ERR(sub_thread); 36256b44003eSAndrew Morton kthread_bind(sub_thread, cpu); 36266b44003eSAndrew Morton wake_up_process(sub_thread); 36276b44003eSAndrew Morton wait_for_completion(&wfc.completion); 36282d3854a3SRusty Russell return wfc.ret; 36292d3854a3SRusty Russell } 36302d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 36312d3854a3SRusty Russell #endif /* CONFIG_SMP */ 36322d3854a3SRusty Russell 3633a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 3634e7577c50SRusty Russell 3635a0a1a5fdSTejun Heo /** 3636a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 3637a0a1a5fdSTejun Heo * 363858a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 363958a69cb4STejun Heo * workqueues will queue new works to their frozen_works list instead of 364058a69cb4STejun Heo * gcwq->worklist. 3641a0a1a5fdSTejun Heo * 3642a0a1a5fdSTejun Heo * CONTEXT: 36438b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3644a0a1a5fdSTejun Heo */ 3645a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 3646a0a1a5fdSTejun Heo { 3647a0a1a5fdSTejun Heo unsigned int cpu; 3648a0a1a5fdSTejun Heo 3649a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3650a0a1a5fdSTejun Heo 3651a0a1a5fdSTejun Heo BUG_ON(workqueue_freezing); 3652a0a1a5fdSTejun Heo workqueue_freezing = true; 3653a0a1a5fdSTejun Heo 3654f3421797STejun Heo for_each_gcwq_cpu(cpu) { 36558b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 3656bdbc5dd7STejun Heo struct workqueue_struct *wq; 36578b03ae3cSTejun Heo 36588b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 36598b03ae3cSTejun Heo 3660db7bccf4STejun Heo BUG_ON(gcwq->flags & GCWQ_FREEZING); 3661db7bccf4STejun Heo gcwq->flags |= GCWQ_FREEZING; 3662db7bccf4STejun Heo 3663a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3664a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3665a0a1a5fdSTejun Heo 366658a69cb4STejun Heo if (cwq && wq->flags & WQ_FREEZABLE) 3667a0a1a5fdSTejun Heo cwq->max_active = 0; 36681da177e4SLinus Torvalds } 36698b03ae3cSTejun Heo 36708b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3671a0a1a5fdSTejun Heo } 3672a0a1a5fdSTejun Heo 3673a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3674a0a1a5fdSTejun Heo } 3675a0a1a5fdSTejun Heo 3676a0a1a5fdSTejun Heo /** 367758a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 3678a0a1a5fdSTejun Heo * 3679a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 3680a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 3681a0a1a5fdSTejun Heo * 3682a0a1a5fdSTejun Heo * CONTEXT: 3683a0a1a5fdSTejun Heo * Grabs and releases workqueue_lock. 3684a0a1a5fdSTejun Heo * 3685a0a1a5fdSTejun Heo * RETURNS: 368658a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 368758a69cb4STejun Heo * is complete. 3688a0a1a5fdSTejun Heo */ 3689a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 3690a0a1a5fdSTejun Heo { 3691a0a1a5fdSTejun Heo unsigned int cpu; 3692a0a1a5fdSTejun Heo bool busy = false; 3693a0a1a5fdSTejun Heo 3694a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3695a0a1a5fdSTejun Heo 3696a0a1a5fdSTejun Heo BUG_ON(!workqueue_freezing); 3697a0a1a5fdSTejun Heo 3698f3421797STejun Heo for_each_gcwq_cpu(cpu) { 3699bdbc5dd7STejun Heo struct workqueue_struct *wq; 3700a0a1a5fdSTejun Heo /* 3701a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 3702a0a1a5fdSTejun Heo * to peek without lock. 3703a0a1a5fdSTejun Heo */ 3704a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3705a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3706a0a1a5fdSTejun Heo 370758a69cb4STejun Heo if (!cwq || !(wq->flags & WQ_FREEZABLE)) 3708a0a1a5fdSTejun Heo continue; 3709a0a1a5fdSTejun Heo 3710a0a1a5fdSTejun Heo BUG_ON(cwq->nr_active < 0); 3711a0a1a5fdSTejun Heo if (cwq->nr_active) { 3712a0a1a5fdSTejun Heo busy = true; 3713a0a1a5fdSTejun Heo goto out_unlock; 3714a0a1a5fdSTejun Heo } 3715a0a1a5fdSTejun Heo } 3716a0a1a5fdSTejun Heo } 3717a0a1a5fdSTejun Heo out_unlock: 3718a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3719a0a1a5fdSTejun Heo return busy; 3720a0a1a5fdSTejun Heo } 3721a0a1a5fdSTejun Heo 3722a0a1a5fdSTejun Heo /** 3723a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 3724a0a1a5fdSTejun Heo * 3725a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 37267e11629dSTejun Heo * frozen works are transferred to their respective gcwq worklists. 3727a0a1a5fdSTejun Heo * 3728a0a1a5fdSTejun Heo * CONTEXT: 37298b03ae3cSTejun Heo * Grabs and releases workqueue_lock and gcwq->lock's. 3730a0a1a5fdSTejun Heo */ 3731a0a1a5fdSTejun Heo void thaw_workqueues(void) 3732a0a1a5fdSTejun Heo { 3733a0a1a5fdSTejun Heo unsigned int cpu; 3734a0a1a5fdSTejun Heo 3735a0a1a5fdSTejun Heo spin_lock(&workqueue_lock); 3736a0a1a5fdSTejun Heo 3737a0a1a5fdSTejun Heo if (!workqueue_freezing) 3738a0a1a5fdSTejun Heo goto out_unlock; 3739a0a1a5fdSTejun Heo 3740f3421797STejun Heo for_each_gcwq_cpu(cpu) { 37418b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 37424ce62e9eSTejun Heo struct worker_pool *pool; 3743bdbc5dd7STejun Heo struct workqueue_struct *wq; 37448b03ae3cSTejun Heo 37458b03ae3cSTejun Heo spin_lock_irq(&gcwq->lock); 37468b03ae3cSTejun Heo 3747db7bccf4STejun Heo BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); 3748db7bccf4STejun Heo gcwq->flags &= ~GCWQ_FREEZING; 3749db7bccf4STejun Heo 3750a0a1a5fdSTejun Heo list_for_each_entry(wq, &workqueues, list) { 3751a0a1a5fdSTejun Heo struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3752a0a1a5fdSTejun Heo 375358a69cb4STejun Heo if (!cwq || !(wq->flags & WQ_FREEZABLE)) 3754a0a1a5fdSTejun Heo continue; 3755a0a1a5fdSTejun Heo 3756a0a1a5fdSTejun Heo /* restore max_active and repopulate worklist */ 3757a0a1a5fdSTejun Heo cwq->max_active = wq->saved_max_active; 3758a0a1a5fdSTejun Heo 3759a0a1a5fdSTejun Heo while (!list_empty(&cwq->delayed_works) && 3760a0a1a5fdSTejun Heo cwq->nr_active < cwq->max_active) 3761a0a1a5fdSTejun Heo cwq_activate_first_delayed(cwq); 3762a0a1a5fdSTejun Heo } 37638b03ae3cSTejun Heo 37644ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) 37654ce62e9eSTejun Heo wake_up_worker(pool); 3766e22bee78STejun Heo 37678b03ae3cSTejun Heo spin_unlock_irq(&gcwq->lock); 3768a0a1a5fdSTejun Heo } 3769a0a1a5fdSTejun Heo 3770a0a1a5fdSTejun Heo workqueue_freezing = false; 3771a0a1a5fdSTejun Heo out_unlock: 3772a0a1a5fdSTejun Heo spin_unlock(&workqueue_lock); 3773a0a1a5fdSTejun Heo } 3774a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 3775a0a1a5fdSTejun Heo 37766ee0578bSSuresh Siddha static int __init init_workqueues(void) 37771da177e4SLinus Torvalds { 3778c34056a3STejun Heo unsigned int cpu; 3779c8e55f36STejun Heo int i; 3780c34056a3STejun Heo 3781b5490077STejun Heo /* make sure we have enough bits for OFFQ CPU number */ 3782b5490077STejun Heo BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_CPU_SHIFT)) < 3783b5490077STejun Heo WORK_CPU_LAST); 3784b5490077STejun Heo 378565758202STejun Heo cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); 378665758202STejun Heo cpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); 37878b03ae3cSTejun Heo 37888b03ae3cSTejun Heo /* initialize gcwqs */ 3789f3421797STejun Heo for_each_gcwq_cpu(cpu) { 37908b03ae3cSTejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 37914ce62e9eSTejun Heo struct worker_pool *pool; 37928b03ae3cSTejun Heo 37938b03ae3cSTejun Heo spin_lock_init(&gcwq->lock); 37948b03ae3cSTejun Heo gcwq->cpu = cpu; 3795f3421797STejun Heo gcwq->flags |= GCWQ_DISASSOCIATED; 37968b03ae3cSTejun Heo 3797c8e55f36STejun Heo for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) 3798c8e55f36STejun Heo INIT_HLIST_HEAD(&gcwq->busy_hash[i]); 3799c8e55f36STejun Heo 38004ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) { 38014ce62e9eSTejun Heo pool->gcwq = gcwq; 38024ce62e9eSTejun Heo INIT_LIST_HEAD(&pool->worklist); 38034ce62e9eSTejun Heo INIT_LIST_HEAD(&pool->idle_list); 3804e22bee78STejun Heo 38054ce62e9eSTejun Heo init_timer_deferrable(&pool->idle_timer); 38064ce62e9eSTejun Heo pool->idle_timer.function = idle_worker_timeout; 38074ce62e9eSTejun Heo pool->idle_timer.data = (unsigned long)pool; 3808e22bee78STejun Heo 38094ce62e9eSTejun Heo setup_timer(&pool->mayday_timer, gcwq_mayday_timeout, 38104ce62e9eSTejun Heo (unsigned long)pool); 38114ce62e9eSTejun Heo 381260373152STejun Heo mutex_init(&pool->manager_mutex); 38134ce62e9eSTejun Heo ida_init(&pool->worker_ida); 38144ce62e9eSTejun Heo } 3815db7bccf4STejun Heo 381625511a47STejun Heo init_waitqueue_head(&gcwq->rebind_hold); 38178b03ae3cSTejun Heo } 38188b03ae3cSTejun Heo 3819e22bee78STejun Heo /* create the initial worker */ 3820f3421797STejun Heo for_each_online_gcwq_cpu(cpu) { 3821e22bee78STejun Heo struct global_cwq *gcwq = get_gcwq(cpu); 38224ce62e9eSTejun Heo struct worker_pool *pool; 3823e22bee78STejun Heo 3824477a3c33STejun Heo if (cpu != WORK_CPU_UNBOUND) 3825477a3c33STejun Heo gcwq->flags &= ~GCWQ_DISASSOCIATED; 38264ce62e9eSTejun Heo 38274ce62e9eSTejun Heo for_each_worker_pool(pool, gcwq) { 38284ce62e9eSTejun Heo struct worker *worker; 38294ce62e9eSTejun Heo 3830bc2ae0f5STejun Heo worker = create_worker(pool); 3831e22bee78STejun Heo BUG_ON(!worker); 3832e22bee78STejun Heo spin_lock_irq(&gcwq->lock); 3833e22bee78STejun Heo start_worker(worker); 3834e22bee78STejun Heo spin_unlock_irq(&gcwq->lock); 3835e22bee78STejun Heo } 38364ce62e9eSTejun Heo } 3837e22bee78STejun Heo 3838d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 38391aabe902SJoonsoo Kim system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 3840d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 3841d320c038STejun Heo system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); 3842f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 3843f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 384424d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 384524d51addSTejun Heo WQ_FREEZABLE, 0); 384662d3c543SAlan Stern system_nrt_freezable_wq = alloc_workqueue("events_nrt_freezable", 384762d3c543SAlan Stern WQ_NON_REENTRANT | WQ_FREEZABLE, 0); 38481aabe902SJoonsoo Kim BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 38491aabe902SJoonsoo Kim !system_nrt_wq || !system_unbound_wq || !system_freezable_wq || 385062d3c543SAlan Stern !system_nrt_freezable_wq); 38516ee0578bSSuresh Siddha return 0; 38521da177e4SLinus Torvalds } 38536ee0578bSSuresh Siddha early_initcall(init_workqueues); 3854