aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/workqueue.c
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r--kernel/workqueue.c3255
1 files changed, 2847 insertions, 408 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 5bfb213984b2..f77afd939229 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1,19 +1,26 @@
1/* 1/*
2 * linux/kernel/workqueue.c 2 * kernel/workqueue.c - generic async execution with shared worker pool
3 * 3 *
4 * Generic mechanism for defining kernel helper threads for running 4 * Copyright (C) 2002 Ingo Molnar
5 * arbitrary tasks in process context.
6 * 5 *
7 * Started by Ingo Molnar, Copyright (C) 2002 6 * Derived from the taskqueue/keventd code by:
7 * David Woodhouse <dwmw2@infradead.org>
8 * Andrew Morton
9 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
10 * Theodore Ts'o <tytso@mit.edu>
8 * 11 *
9 * Derived from the taskqueue/keventd code by: 12 * Made to use alloc_percpu by Christoph Lameter.
10 * 13 *
11 * David Woodhouse <dwmw2@infradead.org> 14 * Copyright (C) 2010 SUSE Linux Products GmbH
12 * Andrew Morton 15 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
13 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
14 * Theodore Ts'o <tytso@mit.edu>
15 * 16 *
16 * Made to use alloc_percpu by Christoph Lameter. 17 * This is the generic async execution mechanism. Work items as are
18 * executed in process context. The worker pool is shared and
19 * automatically managed. There is one worker pool for each CPU and
20 * one extra for works which are better served by workers which are
21 * not bound to any specific CPU.
22 *
23 * Please read Documentation/workqueue.txt for details.
17 */ 24 */
18 25
19#include <linux/module.h> 26#include <linux/module.h>
@@ -33,41 +40,291 @@
33#include <linux/kallsyms.h> 40#include <linux/kallsyms.h>
34#include <linux/debug_locks.h> 41#include <linux/debug_locks.h>
35#include <linux/lockdep.h> 42#include <linux/lockdep.h>
43#include <linux/idr.h>
44
36#define CREATE_TRACE_POINTS 45#define CREATE_TRACE_POINTS
37#include <trace/events/workqueue.h> 46#include <trace/events/workqueue.h>
38 47
48#include "workqueue_sched.h"
49
50enum {
51 /* global_cwq flags */
52 GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
53 GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */
54 GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
55 GCWQ_FREEZING = 1 << 3, /* freeze in progress */
56 GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */
57
58 /* worker flags */
59 WORKER_STARTED = 1 << 0, /* started */
60 WORKER_DIE = 1 << 1, /* die die die */
61 WORKER_IDLE = 1 << 2, /* is idle */
62 WORKER_PREP = 1 << 3, /* preparing to run works */
63 WORKER_ROGUE = 1 << 4, /* not bound to any cpu */
64 WORKER_REBIND = 1 << 5, /* mom is home, come back */
65 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
66 WORKER_UNBOUND = 1 << 7, /* worker is unbound */
67
68 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND |
69 WORKER_CPU_INTENSIVE | WORKER_UNBOUND,
70
71 /* gcwq->trustee_state */
72 TRUSTEE_START = 0, /* start */
73 TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */
74 TRUSTEE_BUTCHER = 2, /* butcher workers */
75 TRUSTEE_RELEASE = 3, /* release workers */
76 TRUSTEE_DONE = 4, /* trustee is done */
77
78 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
79 BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER,
80 BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1,
81
82 MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
83 IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
84
85 MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */
86 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
87 CREATE_COOLDOWN = HZ, /* time to breath after fail */
88 TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */
89
90 /*
91 * Rescue workers are used only on emergencies and shared by
92 * all cpus. Give -20.
93 */
94 RESCUER_NICE_LEVEL = -20,
95};
96
39/* 97/*
40 * The per-CPU workqueue (if single thread, we always use the first 98 * Structure fields follow one of the following exclusion rules.
41 * possible cpu). 99 *
100 * I: Modifiable by initialization/destruction paths and read-only for
101 * everyone else.
102 *
103 * P: Preemption protected. Disabling preemption is enough and should
104 * only be modified and accessed from the local cpu.
105 *
106 * L: gcwq->lock protected. Access with gcwq->lock held.
107 *
108 * X: During normal operation, modification requires gcwq->lock and
109 * should be done only from local cpu. Either disabling preemption
110 * on local cpu or grabbing gcwq->lock is enough for read access.
111 * If GCWQ_DISASSOCIATED is set, it's identical to L.
112 *
113 * F: wq->flush_mutex protected.
114 *
115 * W: workqueue_lock protected.
42 */ 116 */
43struct cpu_workqueue_struct {
44 117
45 spinlock_t lock; 118struct global_cwq;
46 119
47 struct list_head worklist; 120/*
48 wait_queue_head_t more_work; 121 * The poor guys doing the actual heavy lifting. All on-duty workers
49 struct work_struct *current_work; 122 * are either serving the manager role, on idle list or on busy hash.
123 */
124struct worker {
125 /* on idle list while idle, on busy hash table while busy */
126 union {
127 struct list_head entry; /* L: while idle */
128 struct hlist_node hentry; /* L: while busy */
129 };
50 130
51 struct workqueue_struct *wq; 131 struct work_struct *current_work; /* L: work being processed */
52 struct task_struct *thread; 132 struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
53} ____cacheline_aligned; 133 struct list_head scheduled; /* L: scheduled works */
134 struct task_struct *task; /* I: worker task */
135 struct global_cwq *gcwq; /* I: the associated gcwq */
136 /* 64 bytes boundary on 64bit, 32 on 32bit */
137 unsigned long last_active; /* L: last active timestamp */
138 unsigned int flags; /* X: flags */
139 int id; /* I: worker id */
140 struct work_struct rebind_work; /* L: rebind worker to cpu */
141};
142
143/*
144 * Global per-cpu workqueue. There's one and only one for each cpu
145 * and all works are queued and processed here regardless of their
146 * target workqueues.
147 */
148struct global_cwq {
149 spinlock_t lock; /* the gcwq lock */
150 struct list_head worklist; /* L: list of pending works */
151 unsigned int cpu; /* I: the associated cpu */
152 unsigned int flags; /* L: GCWQ_* flags */
153
154 int nr_workers; /* L: total number of workers */
155 int nr_idle; /* L: currently idle ones */
156
157 /* workers are chained either in the idle_list or busy_hash */
158 struct list_head idle_list; /* X: list of idle workers */
159 struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE];
160 /* L: hash of busy workers */
161
162 struct timer_list idle_timer; /* L: worker idle timeout */
163 struct timer_list mayday_timer; /* L: SOS timer for dworkers */
164
165 struct ida worker_ida; /* L: for worker IDs */
166
167 struct task_struct *trustee; /* L: for gcwq shutdown */
168 unsigned int trustee_state; /* L: trustee state */
169 wait_queue_head_t trustee_wait; /* trustee wait */
170 struct worker *first_idle; /* L: first idle worker */
171} ____cacheline_aligned_in_smp;
172
173/*
174 * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
175 * work_struct->data are used for flags and thus cwqs need to be
176 * aligned at two's power of the number of flag bits.
177 */
178struct cpu_workqueue_struct {
179 struct global_cwq *gcwq; /* I: the associated gcwq */
180 struct workqueue_struct *wq; /* I: the owning workqueue */
181 int work_color; /* L: current color */
182 int flush_color; /* L: flushing color */
183 int nr_in_flight[WORK_NR_COLORS];
184 /* L: nr of in_flight works */
185 int nr_active; /* L: nr of active works */
186 int max_active; /* L: max active works */
187 struct list_head delayed_works; /* L: delayed works */
188};
189
190/*
191 * Structure used to wait for workqueue flush.
192 */
193struct wq_flusher {
194 struct list_head list; /* F: list of flushers */
195 int flush_color; /* F: flush color waiting for */
196 struct completion done; /* flush completion */
197};
198
199/*
200 * All cpumasks are assumed to be always set on UP and thus can't be
201 * used to determine whether there's something to be done.
202 */
203#ifdef CONFIG_SMP
204typedef cpumask_var_t mayday_mask_t;
205#define mayday_test_and_set_cpu(cpu, mask) \
206 cpumask_test_and_set_cpu((cpu), (mask))
207#define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
208#define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
209#define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
210#define free_mayday_mask(mask) free_cpumask_var((mask))
211#else
212typedef unsigned long mayday_mask_t;
213#define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
214#define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
215#define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
216#define alloc_mayday_mask(maskp, gfp) true
217#define free_mayday_mask(mask) do { } while (0)
218#endif
54 219
55/* 220/*
56 * The externally visible workqueue abstraction is an array of 221 * The externally visible workqueue abstraction is an array of
57 * per-CPU workqueues: 222 * per-CPU workqueues:
58 */ 223 */
59struct workqueue_struct { 224struct workqueue_struct {
60 struct cpu_workqueue_struct *cpu_wq; 225 unsigned int flags; /* I: WQ_* flags */
61 struct list_head list; 226 union {
62 const char *name; 227 struct cpu_workqueue_struct __percpu *pcpu;
63 int singlethread; 228 struct cpu_workqueue_struct *single;
64 int freezeable; /* Freeze threads during suspend */ 229 unsigned long v;
65 int rt; 230 } cpu_wq; /* I: cwq's */
231 struct list_head list; /* W: list of all workqueues */
232
233 struct mutex flush_mutex; /* protects wq flushing */
234 int work_color; /* F: current work color */
235 int flush_color; /* F: current flush color */
236 atomic_t nr_cwqs_to_flush; /* flush in progress */
237 struct wq_flusher *first_flusher; /* F: first flusher */
238 struct list_head flusher_queue; /* F: flush waiters */
239 struct list_head flusher_overflow; /* F: flush overflow list */
240
241 mayday_mask_t mayday_mask; /* cpus requesting rescue */
242 struct worker *rescuer; /* I: rescue worker */
243
244 int saved_max_active; /* W: saved cwq max_active */
245 const char *name; /* I: workqueue name */
66#ifdef CONFIG_LOCKDEP 246#ifdef CONFIG_LOCKDEP
67 struct lockdep_map lockdep_map; 247 struct lockdep_map lockdep_map;
68#endif 248#endif
69}; 249};
70 250
251struct workqueue_struct *system_wq __read_mostly;
252struct workqueue_struct *system_long_wq __read_mostly;
253struct workqueue_struct *system_nrt_wq __read_mostly;
254struct workqueue_struct *system_unbound_wq __read_mostly;
255EXPORT_SYMBOL_GPL(system_wq);
256EXPORT_SYMBOL_GPL(system_long_wq);
257EXPORT_SYMBOL_GPL(system_nrt_wq);
258EXPORT_SYMBOL_GPL(system_unbound_wq);
259
260#define for_each_busy_worker(worker, i, pos, gcwq) \
261 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
262 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
263
264static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
265 unsigned int sw)
266{
267 if (cpu < nr_cpu_ids) {
268 if (sw & 1) {
269 cpu = cpumask_next(cpu, mask);
270 if (cpu < nr_cpu_ids)
271 return cpu;
272 }
273 if (sw & 2)
274 return WORK_CPU_UNBOUND;
275 }
276 return WORK_CPU_NONE;
277}
278
279static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
280 struct workqueue_struct *wq)
281{
282 return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
283}
284
285/*
286 * CPU iterators
287 *
288 * An extra gcwq is defined for an invalid cpu number
289 * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
290 * specific CPU. The following iterators are similar to
291 * for_each_*_cpu() iterators but also considers the unbound gcwq.
292 *
293 * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
294 * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
295 * for_each_cwq_cpu() : possible CPUs for bound workqueues,
296 * WORK_CPU_UNBOUND for unbound workqueues
297 */
298#define for_each_gcwq_cpu(cpu) \
299 for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
300 (cpu) < WORK_CPU_NONE; \
301 (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
302
303#define for_each_online_gcwq_cpu(cpu) \
304 for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
305 (cpu) < WORK_CPU_NONE; \
306 (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
307
308#define for_each_cwq_cpu(cpu, wq) \
309 for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
310 (cpu) < WORK_CPU_NONE; \
311 (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
312
313#ifdef CONFIG_LOCKDEP
314/**
315 * in_workqueue_context() - in context of specified workqueue?
316 * @wq: the workqueue of interest
317 *
318 * Checks lockdep state to see if the current task is executing from
319 * within a workqueue item. This function exists only if lockdep is
320 * enabled.
321 */
322int in_workqueue_context(struct workqueue_struct *wq)
323{
324 return lock_is_held(&wq->lockdep_map);
325}
326#endif
327
71#ifdef CONFIG_DEBUG_OBJECTS_WORK 328#ifdef CONFIG_DEBUG_OBJECTS_WORK
72 329
73static struct debug_obj_descr work_debug_descr; 330static struct debug_obj_descr work_debug_descr;
@@ -107,7 +364,7 @@ static int work_fixup_activate(void *addr, enum debug_obj_state state)
107 * statically initialized. We just make sure that it 364 * statically initialized. We just make sure that it
108 * is tracked in the object tracker. 365 * is tracked in the object tracker.
109 */ 366 */
110 if (test_bit(WORK_STRUCT_STATIC, work_data_bits(work))) { 367 if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) {
111 debug_object_init(work, &work_debug_descr); 368 debug_object_init(work, &work_debug_descr);
112 debug_object_activate(work, &work_debug_descr); 369 debug_object_activate(work, &work_debug_descr);
113 return 0; 370 return 0;
@@ -181,84 +438,582 @@ static inline void debug_work_deactivate(struct work_struct *work) { }
181/* Serializes the accesses to the list of workqueues. */ 438/* Serializes the accesses to the list of workqueues. */
182static DEFINE_SPINLOCK(workqueue_lock); 439static DEFINE_SPINLOCK(workqueue_lock);
183static LIST_HEAD(workqueues); 440static LIST_HEAD(workqueues);
441static bool workqueue_freezing; /* W: have wqs started freezing? */
184 442
185static int singlethread_cpu __read_mostly;
186static const struct cpumask *cpu_singlethread_map __read_mostly;
187/* 443/*
188 * _cpu_down() first removes CPU from cpu_online_map, then CPU_DEAD 444 * The almighty global cpu workqueues. nr_running is the only field
189 * flushes cwq->worklist. This means that flush_workqueue/wait_on_work 445 * which is expected to be used frequently by other cpus via
190 * which comes in between can't use for_each_online_cpu(). We could 446 * try_to_wake_up(). Put it in a separate cacheline.
191 * use cpu_possible_map, the cpumask below is more a documentation
192 * than optimization.
193 */ 447 */
194static cpumask_var_t cpu_populated_map __read_mostly; 448static DEFINE_PER_CPU(struct global_cwq, global_cwq);
449static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);
450
451/*
452 * Global cpu workqueue and nr_running counter for unbound gcwq. The
453 * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
454 * workers have WORKER_UNBOUND set.
455 */
456static struct global_cwq unbound_global_cwq;
457static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */
458
459static int worker_thread(void *__worker);
460
461static struct global_cwq *get_gcwq(unsigned int cpu)
462{
463 if (cpu != WORK_CPU_UNBOUND)
464 return &per_cpu(global_cwq, cpu);
465 else
466 return &unbound_global_cwq;
467}
468
469static atomic_t *get_gcwq_nr_running(unsigned int cpu)
470{
471 if (cpu != WORK_CPU_UNBOUND)
472 return &per_cpu(gcwq_nr_running, cpu);
473 else
474 return &unbound_gcwq_nr_running;
475}
195 476
196/* If it's single threaded, it isn't in the list of workqueues. */ 477static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
197static inline int is_wq_single_threaded(struct workqueue_struct *wq) 478 struct workqueue_struct *wq)
198{ 479{
199 return wq->singlethread; 480 if (!(wq->flags & WQ_UNBOUND)) {
481 if (likely(cpu < nr_cpu_ids)) {
482#ifdef CONFIG_SMP
483 return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
484#else
485 return wq->cpu_wq.single;
486#endif
487 }
488 } else if (likely(cpu == WORK_CPU_UNBOUND))
489 return wq->cpu_wq.single;
490 return NULL;
200} 491}
201 492
202static const struct cpumask *wq_cpu_map(struct workqueue_struct *wq) 493static unsigned int work_color_to_flags(int color)
203{ 494{
204 return is_wq_single_threaded(wq) 495 return color << WORK_STRUCT_COLOR_SHIFT;
205 ? cpu_singlethread_map : cpu_populated_map;
206} 496}
207 497
208static 498static int get_work_color(struct work_struct *work)
209struct cpu_workqueue_struct *wq_per_cpu(struct workqueue_struct *wq, int cpu)
210{ 499{
211 if (unlikely(is_wq_single_threaded(wq))) 500 return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
212 cpu = singlethread_cpu; 501 ((1 << WORK_STRUCT_COLOR_BITS) - 1);
213 return per_cpu_ptr(wq->cpu_wq, cpu); 502}
503
504static int work_next_color(int color)
505{
506 return (color + 1) % WORK_NR_COLORS;
214} 507}
215 508
216/* 509/*
217 * Set the workqueue on which a work item is to be run 510 * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
218 * - Must *only* be called if the pending flag is set 511 * work is on queue. Once execution starts, WORK_STRUCT_CWQ is
512 * cleared and the work data contains the cpu number it was last on.
513 *
514 * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
515 * cwq, cpu or clear work->data. These functions should only be
516 * called while the work is owned - ie. while the PENDING bit is set.
517 *
518 * get_work_[g]cwq() can be used to obtain the gcwq or cwq
519 * corresponding to a work. gcwq is available once the work has been
520 * queued anywhere after initialization. cwq is available only from
521 * queueing until execution starts.
219 */ 522 */
220static inline void set_wq_data(struct work_struct *work, 523static inline void set_work_data(struct work_struct *work, unsigned long data,
221 struct cpu_workqueue_struct *cwq) 524 unsigned long flags)
222{ 525{
223 unsigned long new;
224
225 BUG_ON(!work_pending(work)); 526 BUG_ON(!work_pending(work));
527 atomic_long_set(&work->data, data | flags | work_static(work));
528}
529
530static void set_work_cwq(struct work_struct *work,
531 struct cpu_workqueue_struct *cwq,
532 unsigned long extra_flags)
533{
534 set_work_data(work, (unsigned long)cwq,
535 WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
536}
537
538static void set_work_cpu(struct work_struct *work, unsigned int cpu)
539{
540 set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING);
541}
542
543static void clear_work_data(struct work_struct *work)
544{
545 set_work_data(work, WORK_STRUCT_NO_CPU, 0);
546}
547
548static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
549{
550 unsigned long data = atomic_long_read(&work->data);
551
552 if (data & WORK_STRUCT_CWQ)
553 return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
554 else
555 return NULL;
556}
557
558static struct global_cwq *get_work_gcwq(struct work_struct *work)
559{
560 unsigned long data = atomic_long_read(&work->data);
561 unsigned int cpu;
562
563 if (data & WORK_STRUCT_CWQ)
564 return ((struct cpu_workqueue_struct *)
565 (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq;
566
567 cpu = data >> WORK_STRUCT_FLAG_BITS;
568 if (cpu == WORK_CPU_NONE)
569 return NULL;
226 570
227 new = (unsigned long) cwq | (1UL << WORK_STRUCT_PENDING); 571 BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND);
228 new |= WORK_STRUCT_FLAG_MASK & *work_data_bits(work); 572 return get_gcwq(cpu);
229 atomic_long_set(&work->data, new); 573}
574
575/*
576 * Policy functions. These define the policies on how the global
577 * worker pool is managed. Unless noted otherwise, these functions
578 * assume that they're being called with gcwq->lock held.
579 */
580
581static bool __need_more_worker(struct global_cwq *gcwq)
582{
583 return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) ||
584 gcwq->flags & GCWQ_HIGHPRI_PENDING;
585}
586
587/*
588 * Need to wake up a worker? Called from anything but currently
589 * running workers.
590 */
591static bool need_more_worker(struct global_cwq *gcwq)
592{
593 return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq);
230} 594}
231 595
232static inline 596/* Can I start working? Called from busy but !running workers. */
233struct cpu_workqueue_struct *get_wq_data(struct work_struct *work) 597static bool may_start_working(struct global_cwq *gcwq)
234{ 598{
235 return (void *) (atomic_long_read(&work->data) & WORK_STRUCT_WQ_DATA_MASK); 599 return gcwq->nr_idle;
236} 600}
237 601
602/* Do I need to keep working? Called from currently running workers. */
603static bool keep_working(struct global_cwq *gcwq)
604{
605 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
606
607 return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1;
608}
609
610/* Do we need a new worker? Called from manager. */
611static bool need_to_create_worker(struct global_cwq *gcwq)
612{
613 return need_more_worker(gcwq) && !may_start_working(gcwq);
614}
615
616/* Do I need to be the manager? */
617static bool need_to_manage_workers(struct global_cwq *gcwq)
618{
619 return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS;
620}
621
622/* Do we have too many workers and should some go away? */
623static bool too_many_workers(struct global_cwq *gcwq)
624{
625 bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS;
626 int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */
627 int nr_busy = gcwq->nr_workers - nr_idle;
628
629 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
630}
631
632/*
633 * Wake up functions.
634 */
635
636/* Return the first worker. Safe with preemption disabled */
637static struct worker *first_worker(struct global_cwq *gcwq)
638{
639 if (unlikely(list_empty(&gcwq->idle_list)))
640 return NULL;
641
642 return list_first_entry(&gcwq->idle_list, struct worker, entry);
643}
644
645/**
646 * wake_up_worker - wake up an idle worker
647 * @gcwq: gcwq to wake worker for
648 *
649 * Wake up the first idle worker of @gcwq.
650 *
651 * CONTEXT:
652 * spin_lock_irq(gcwq->lock).
653 */
654static void wake_up_worker(struct global_cwq *gcwq)
655{
656 struct worker *worker = first_worker(gcwq);
657
658 if (likely(worker))
659 wake_up_process(worker->task);
660}
661
662/**
663 * wq_worker_waking_up - a worker is waking up
664 * @task: task waking up
665 * @cpu: CPU @task is waking up to
666 *
667 * This function is called during try_to_wake_up() when a worker is
668 * being awoken.
669 *
670 * CONTEXT:
671 * spin_lock_irq(rq->lock)
672 */
673void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
674{
675 struct worker *worker = kthread_data(task);
676
677 if (likely(!(worker->flags & WORKER_NOT_RUNNING)))
678 atomic_inc(get_gcwq_nr_running(cpu));
679}
680
681/**
682 * wq_worker_sleeping - a worker is going to sleep
683 * @task: task going to sleep
684 * @cpu: CPU in question, must be the current CPU number
685 *
686 * This function is called during schedule() when a busy worker is
687 * going to sleep. Worker on the same cpu can be woken up by
688 * returning pointer to its task.
689 *
690 * CONTEXT:
691 * spin_lock_irq(rq->lock)
692 *
693 * RETURNS:
694 * Worker task on @cpu to wake up, %NULL if none.
695 */
696struct task_struct *wq_worker_sleeping(struct task_struct *task,
697 unsigned int cpu)
698{
699 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
700 struct global_cwq *gcwq = get_gcwq(cpu);
701 atomic_t *nr_running = get_gcwq_nr_running(cpu);
702
703 if (unlikely(worker->flags & WORKER_NOT_RUNNING))
704 return NULL;
705
706 /* this can only happen on the local cpu */
707 BUG_ON(cpu != raw_smp_processor_id());
708
709 /*
710 * The counterpart of the following dec_and_test, implied mb,
711 * worklist not empty test sequence is in insert_work().
712 * Please read comment there.
713 *
714 * NOT_RUNNING is clear. This means that trustee is not in
715 * charge and we're running on the local cpu w/ rq lock held
716 * and preemption disabled, which in turn means that none else
717 * could be manipulating idle_list, so dereferencing idle_list
718 * without gcwq lock is safe.
719 */
720 if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist))
721 to_wakeup = first_worker(gcwq);
722 return to_wakeup ? to_wakeup->task : NULL;
723}
724
725/**
726 * worker_set_flags - set worker flags and adjust nr_running accordingly
727 * @worker: self
728 * @flags: flags to set
729 * @wakeup: wakeup an idle worker if necessary
730 *
731 * Set @flags in @worker->flags and adjust nr_running accordingly. If
732 * nr_running becomes zero and @wakeup is %true, an idle worker is
733 * woken up.
734 *
735 * CONTEXT:
736 * spin_lock_irq(gcwq->lock)
737 */
738static inline void worker_set_flags(struct worker *worker, unsigned int flags,
739 bool wakeup)
740{
741 struct global_cwq *gcwq = worker->gcwq;
742
743 WARN_ON_ONCE(worker->task != current);
744
745 /*
746 * If transitioning into NOT_RUNNING, adjust nr_running and
747 * wake up an idle worker as necessary if requested by
748 * @wakeup.
749 */
750 if ((flags & WORKER_NOT_RUNNING) &&
751 !(worker->flags & WORKER_NOT_RUNNING)) {
752 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu);
753
754 if (wakeup) {
755 if (atomic_dec_and_test(nr_running) &&
756 !list_empty(&gcwq->worklist))
757 wake_up_worker(gcwq);
758 } else
759 atomic_dec(nr_running);
760 }
761
762 worker->flags |= flags;
763}
764
765/**
766 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
767 * @worker: self
768 * @flags: flags to clear
769 *
770 * Clear @flags in @worker->flags and adjust nr_running accordingly.
771 *
772 * CONTEXT:
773 * spin_lock_irq(gcwq->lock)
774 */
775static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
776{
777 struct global_cwq *gcwq = worker->gcwq;
778 unsigned int oflags = worker->flags;
779
780 WARN_ON_ONCE(worker->task != current);
781
782 worker->flags &= ~flags;
783
784 /* if transitioning out of NOT_RUNNING, increment nr_running */
785 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
786 if (!(worker->flags & WORKER_NOT_RUNNING))
787 atomic_inc(get_gcwq_nr_running(gcwq->cpu));
788}
789
790/**
791 * busy_worker_head - return the busy hash head for a work
792 * @gcwq: gcwq of interest
793 * @work: work to be hashed
794 *
795 * Return hash head of @gcwq for @work.
796 *
797 * CONTEXT:
798 * spin_lock_irq(gcwq->lock).
799 *
800 * RETURNS:
801 * Pointer to the hash head.
802 */
803static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
804 struct work_struct *work)
805{
806 const int base_shift = ilog2(sizeof(struct work_struct));
807 unsigned long v = (unsigned long)work;
808
809 /* simple shift and fold hash, do we need something better? */
810 v >>= base_shift;
811 v += v >> BUSY_WORKER_HASH_ORDER;
812 v &= BUSY_WORKER_HASH_MASK;
813
814 return &gcwq->busy_hash[v];
815}
816
817/**
818 * __find_worker_executing_work - find worker which is executing a work
819 * @gcwq: gcwq of interest
820 * @bwh: hash head as returned by busy_worker_head()
821 * @work: work to find worker for
822 *
823 * Find a worker which is executing @work on @gcwq. @bwh should be
824 * the hash head obtained by calling busy_worker_head() with the same
825 * work.
826 *
827 * CONTEXT:
828 * spin_lock_irq(gcwq->lock).
829 *
830 * RETURNS:
831 * Pointer to worker which is executing @work if found, NULL
832 * otherwise.
833 */
834static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,
835 struct hlist_head *bwh,
836 struct work_struct *work)
837{
838 struct worker *worker;
839 struct hlist_node *tmp;
840
841 hlist_for_each_entry(worker, tmp, bwh, hentry)
842 if (worker->current_work == work)
843 return worker;
844 return NULL;
845}
846
847/**
848 * find_worker_executing_work - find worker which is executing a work
849 * @gcwq: gcwq of interest
850 * @work: work to find worker for
851 *
852 * Find a worker which is executing @work on @gcwq. This function is
853 * identical to __find_worker_executing_work() except that this
854 * function calculates @bwh itself.
855 *
856 * CONTEXT:
857 * spin_lock_irq(gcwq->lock).
858 *
859 * RETURNS:
860 * Pointer to worker which is executing @work if found, NULL
861 * otherwise.
862 */
863static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
864 struct work_struct *work)
865{
866 return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),
867 work);
868}
869
870/**
871 * gcwq_determine_ins_pos - find insertion position
872 * @gcwq: gcwq of interest
873 * @cwq: cwq a work is being queued for
874 *
875 * A work for @cwq is about to be queued on @gcwq, determine insertion
876 * position for the work. If @cwq is for HIGHPRI wq, the work is
877 * queued at the head of the queue but in FIFO order with respect to
878 * other HIGHPRI works; otherwise, at the end of the queue. This
879 * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that
880 * there are HIGHPRI works pending.
881 *
882 * CONTEXT:
883 * spin_lock_irq(gcwq->lock).
884 *
885 * RETURNS:
886 * Pointer to inserstion position.
887 */
888static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq,
889 struct cpu_workqueue_struct *cwq)
890{
891 struct work_struct *twork;
892
893 if (likely(!(cwq->wq->flags & WQ_HIGHPRI)))
894 return &gcwq->worklist;
895
896 list_for_each_entry(twork, &gcwq->worklist, entry) {
897 struct cpu_workqueue_struct *tcwq = get_work_cwq(twork);
898
899 if (!(tcwq->wq->flags & WQ_HIGHPRI))
900 break;
901 }
902
903 gcwq->flags |= GCWQ_HIGHPRI_PENDING;
904 return &twork->entry;
905}
906
907/**
908 * insert_work - insert a work into gcwq
909 * @cwq: cwq @work belongs to
910 * @work: work to insert
911 * @head: insertion point
912 * @extra_flags: extra WORK_STRUCT_* flags to set
913 *
914 * Insert @work which belongs to @cwq into @gcwq after @head.
915 * @extra_flags is or'd to work_struct flags.
916 *
917 * CONTEXT:
918 * spin_lock_irq(gcwq->lock).
919 */
238static void insert_work(struct cpu_workqueue_struct *cwq, 920static void insert_work(struct cpu_workqueue_struct *cwq,
239 struct work_struct *work, struct list_head *head) 921 struct work_struct *work, struct list_head *head,
922 unsigned int extra_flags)
240{ 923{
241 trace_workqueue_insertion(cwq->thread, work); 924 struct global_cwq *gcwq = cwq->gcwq;
925
926 /* we own @work, set data and link */
927 set_work_cwq(work, cwq, extra_flags);
242 928
243 set_wq_data(work, cwq);
244 /* 929 /*
245 * Ensure that we get the right work->data if we see the 930 * Ensure that we get the right work->data if we see the
246 * result of list_add() below, see try_to_grab_pending(). 931 * result of list_add() below, see try_to_grab_pending().
247 */ 932 */
248 smp_wmb(); 933 smp_wmb();
934
249 list_add_tail(&work->entry, head); 935 list_add_tail(&work->entry, head);
250 wake_up(&cwq->more_work); 936
937 /*
938 * Ensure either worker_sched_deactivated() sees the above
939 * list_add_tail() or we see zero nr_running to avoid workers
940 * lying around lazily while there are works to be processed.
941 */
942 smp_mb();
943
944 if (__need_more_worker(gcwq))
945 wake_up_worker(gcwq);
251} 946}
252 947
253static void __queue_work(struct cpu_workqueue_struct *cwq, 948static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
254 struct work_struct *work) 949 struct work_struct *work)
255{ 950{
951 struct global_cwq *gcwq;
952 struct cpu_workqueue_struct *cwq;
953 struct list_head *worklist;
954 unsigned int work_flags;
256 unsigned long flags; 955 unsigned long flags;
257 956
258 debug_work_activate(work); 957 debug_work_activate(work);
259 spin_lock_irqsave(&cwq->lock, flags); 958
260 insert_work(cwq, work, &cwq->worklist); 959 if (WARN_ON_ONCE(wq->flags & WQ_DYING))
261 spin_unlock_irqrestore(&cwq->lock, flags); 960 return;
961
962 /* determine gcwq to use */
963 if (!(wq->flags & WQ_UNBOUND)) {
964 struct global_cwq *last_gcwq;
965
966 if (unlikely(cpu == WORK_CPU_UNBOUND))
967 cpu = raw_smp_processor_id();
968
969 /*
970 * It's multi cpu. If @wq is non-reentrant and @work
971 * was previously on a different cpu, it might still
972 * be running there, in which case the work needs to
973 * be queued on that cpu to guarantee non-reentrance.
974 */
975 gcwq = get_gcwq(cpu);
976 if (wq->flags & WQ_NON_REENTRANT &&
977 (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) {
978 struct worker *worker;
979
980 spin_lock_irqsave(&last_gcwq->lock, flags);
981
982 worker = find_worker_executing_work(last_gcwq, work);
983
984 if (worker && worker->current_cwq->wq == wq)
985 gcwq = last_gcwq;
986 else {
987 /* meh... not running there, queue here */
988 spin_unlock_irqrestore(&last_gcwq->lock, flags);
989 spin_lock_irqsave(&gcwq->lock, flags);
990 }
991 } else
992 spin_lock_irqsave(&gcwq->lock, flags);
993 } else {
994 gcwq = get_gcwq(WORK_CPU_UNBOUND);
995 spin_lock_irqsave(&gcwq->lock, flags);
996 }
997
998 /* gcwq determined, get cwq and queue */
999 cwq = get_cwq(gcwq->cpu, wq);
1000
1001 BUG_ON(!list_empty(&work->entry));
1002
1003 cwq->nr_in_flight[cwq->work_color]++;
1004 work_flags = work_color_to_flags(cwq->work_color);
1005
1006 if (likely(cwq->nr_active < cwq->max_active)) {
1007 cwq->nr_active++;
1008 worklist = gcwq_determine_ins_pos(gcwq, cwq);
1009 } else {
1010 work_flags |= WORK_STRUCT_DELAYED;
1011 worklist = &cwq->delayed_works;
1012 }
1013
1014 insert_work(cwq, work, worklist, work_flags);
1015
1016 spin_unlock_irqrestore(&gcwq->lock, flags);
262} 1017}
263 1018
264/** 1019/**
@@ -298,9 +1053,8 @@ queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work)
298{ 1053{
299 int ret = 0; 1054 int ret = 0;
300 1055
301 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { 1056 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
302 BUG_ON(!list_empty(&work->entry)); 1057 __queue_work(cpu, wq, work);
303 __queue_work(wq_per_cpu(wq, cpu), work);
304 ret = 1; 1058 ret = 1;
305 } 1059 }
306 return ret; 1060 return ret;
@@ -310,10 +1064,9 @@ EXPORT_SYMBOL_GPL(queue_work_on);
310static void delayed_work_timer_fn(unsigned long __data) 1064static void delayed_work_timer_fn(unsigned long __data)
311{ 1065{
312 struct delayed_work *dwork = (struct delayed_work *)__data; 1066 struct delayed_work *dwork = (struct delayed_work *)__data;
313 struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work); 1067 struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
314 struct workqueue_struct *wq = cwq->wq;
315 1068
316 __queue_work(wq_per_cpu(wq, smp_processor_id()), &dwork->work); 1069 __queue_work(smp_processor_id(), cwq->wq, &dwork->work);
317} 1070}
318 1071
319/** 1072/**
@@ -350,14 +1103,31 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
350 struct timer_list *timer = &dwork->timer; 1103 struct timer_list *timer = &dwork->timer;
351 struct work_struct *work = &dwork->work; 1104 struct work_struct *work = &dwork->work;
352 1105
353 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) { 1106 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1107 unsigned int lcpu;
1108
354 BUG_ON(timer_pending(timer)); 1109 BUG_ON(timer_pending(timer));
355 BUG_ON(!list_empty(&work->entry)); 1110 BUG_ON(!list_empty(&work->entry));
356 1111
357 timer_stats_timer_set_start_info(&dwork->timer); 1112 timer_stats_timer_set_start_info(&dwork->timer);
358 1113
359 /* This stores cwq for the moment, for the timer_fn */ 1114 /*
360 set_wq_data(work, wq_per_cpu(wq, raw_smp_processor_id())); 1115 * This stores cwq for the moment, for the timer_fn.
1116 * Note that the work's gcwq is preserved to allow
1117 * reentrance detection for delayed works.
1118 */
1119 if (!(wq->flags & WQ_UNBOUND)) {
1120 struct global_cwq *gcwq = get_work_gcwq(work);
1121
1122 if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND)
1123 lcpu = gcwq->cpu;
1124 else
1125 lcpu = raw_smp_processor_id();
1126 } else
1127 lcpu = WORK_CPU_UNBOUND;
1128
1129 set_work_cwq(work, get_cwq(lcpu, wq), 0);
1130
361 timer->expires = jiffies + delay; 1131 timer->expires = jiffies + delay;
362 timer->data = (unsigned long)dwork; 1132 timer->data = (unsigned long)dwork;
363 timer->function = delayed_work_timer_fn; 1133 timer->function = delayed_work_timer_fn;
@@ -372,80 +1142,888 @@ int queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
372} 1142}
373EXPORT_SYMBOL_GPL(queue_delayed_work_on); 1143EXPORT_SYMBOL_GPL(queue_delayed_work_on);
374 1144
375static void run_workqueue(struct cpu_workqueue_struct *cwq) 1145/**
1146 * worker_enter_idle - enter idle state
1147 * @worker: worker which is entering idle state
1148 *
1149 * @worker is entering idle state. Update stats and idle timer if
1150 * necessary.
1151 *
1152 * LOCKING:
1153 * spin_lock_irq(gcwq->lock).
1154 */
1155static void worker_enter_idle(struct worker *worker)
376{ 1156{
377 spin_lock_irq(&cwq->lock); 1157 struct global_cwq *gcwq = worker->gcwq;
378 while (!list_empty(&cwq->worklist)) { 1158
379 struct work_struct *work = list_entry(cwq->worklist.next, 1159 BUG_ON(worker->flags & WORKER_IDLE);
380 struct work_struct, entry); 1160 BUG_ON(!list_empty(&worker->entry) &&
381 work_func_t f = work->func; 1161 (worker->hentry.next || worker->hentry.pprev));
382#ifdef CONFIG_LOCKDEP 1162
1163 /* can't use worker_set_flags(), also called from start_worker() */
1164 worker->flags |= WORKER_IDLE;
1165 gcwq->nr_idle++;
1166 worker->last_active = jiffies;
1167
1168 /* idle_list is LIFO */
1169 list_add(&worker->entry, &gcwq->idle_list);
1170
1171 if (likely(!(worker->flags & WORKER_ROGUE))) {
1172 if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer))
1173 mod_timer(&gcwq->idle_timer,
1174 jiffies + IDLE_WORKER_TIMEOUT);
1175 } else
1176 wake_up_all(&gcwq->trustee_wait);
1177
1178 /* sanity check nr_running */
1179 WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle &&
1180 atomic_read(get_gcwq_nr_running(gcwq->cpu)));
1181}
1182
1183/**
1184 * worker_leave_idle - leave idle state
1185 * @worker: worker which is leaving idle state
1186 *
1187 * @worker is leaving idle state. Update stats.
1188 *
1189 * LOCKING:
1190 * spin_lock_irq(gcwq->lock).
1191 */
1192static void worker_leave_idle(struct worker *worker)
1193{
1194 struct global_cwq *gcwq = worker->gcwq;
1195
1196 BUG_ON(!(worker->flags & WORKER_IDLE));
1197 worker_clr_flags(worker, WORKER_IDLE);
1198 gcwq->nr_idle--;
1199 list_del_init(&worker->entry);
1200}
1201
1202/**
1203 * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
1204 * @worker: self
1205 *
1206 * Works which are scheduled while the cpu is online must at least be
1207 * scheduled to a worker which is bound to the cpu so that if they are
1208 * flushed from cpu callbacks while cpu is going down, they are
1209 * guaranteed to execute on the cpu.
1210 *
1211 * This function is to be used by rogue workers and rescuers to bind
1212 * themselves to the target cpu and may race with cpu going down or
1213 * coming online. kthread_bind() can't be used because it may put the
1214 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1215 * verbatim as it's best effort and blocking and gcwq may be
1216 * [dis]associated in the meantime.
1217 *
1218 * This function tries set_cpus_allowed() and locks gcwq and verifies
1219 * the binding against GCWQ_DISASSOCIATED which is set during
1220 * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters
1221 * idle state or fetches works without dropping lock, it can guarantee
1222 * the scheduling requirement described in the first paragraph.
1223 *
1224 * CONTEXT:
1225 * Might sleep. Called without any lock but returns with gcwq->lock
1226 * held.
1227 *
1228 * RETURNS:
1229 * %true if the associated gcwq is online (@worker is successfully
1230 * bound), %false if offline.
1231 */
1232static bool worker_maybe_bind_and_lock(struct worker *worker)
1233__acquires(&gcwq->lock)
1234{
1235 struct global_cwq *gcwq = worker->gcwq;
1236 struct task_struct *task = worker->task;
1237
1238 while (true) {
383 /* 1239 /*
384 * It is permissible to free the struct work_struct 1240 * The following call may fail, succeed or succeed
385 * from inside the function that is called from it, 1241 * without actually migrating the task to the cpu if
386 * this we need to take into account for lockdep too. 1242 * it races with cpu hotunplug operation. Verify
387 * To avoid bogus "held lock freed" warnings as well 1243 * against GCWQ_DISASSOCIATED.
388 * as problems when looking into work->lockdep_map,
389 * make a copy and use that here.
390 */ 1244 */
391 struct lockdep_map lockdep_map = work->lockdep_map; 1245 if (!(gcwq->flags & GCWQ_DISASSOCIATED))
392#endif 1246 set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
393 trace_workqueue_execution(cwq->thread, work); 1247
394 debug_work_deactivate(work); 1248 spin_lock_irq(&gcwq->lock);
395 cwq->current_work = work; 1249 if (gcwq->flags & GCWQ_DISASSOCIATED)
396 list_del_init(cwq->worklist.next); 1250 return false;
397 spin_unlock_irq(&cwq->lock); 1251 if (task_cpu(task) == gcwq->cpu &&
398 1252 cpumask_equal(&current->cpus_allowed,
399 BUG_ON(get_wq_data(work) != cwq); 1253 get_cpu_mask(gcwq->cpu)))
400 work_clear_pending(work); 1254 return true;
401 lock_map_acquire(&cwq->wq->lockdep_map); 1255 spin_unlock_irq(&gcwq->lock);
402 lock_map_acquire(&lockdep_map); 1256
403 f(work); 1257 /* CPU has come up inbetween, retry migration */
404 lock_map_release(&lockdep_map); 1258 cpu_relax();
405 lock_map_release(&cwq->wq->lockdep_map); 1259 }
406 1260}
407 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 1261
408 printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " 1262/*
409 "%s/0x%08x/%d\n", 1263 * Function for worker->rebind_work used to rebind rogue busy workers
410 current->comm, preempt_count(), 1264 * to the associated cpu which is coming back online. This is
411 task_pid_nr(current)); 1265 * scheduled by cpu up but can race with other cpu hotplug operations
412 printk(KERN_ERR " last function: "); 1266 * and may be executed twice without intervening cpu down.
413 print_symbol("%s\n", (unsigned long)f); 1267 */
414 debug_show_held_locks(current); 1268static void worker_rebind_fn(struct work_struct *work)
415 dump_stack(); 1269{
1270 struct worker *worker = container_of(work, struct worker, rebind_work);
1271 struct global_cwq *gcwq = worker->gcwq;
1272
1273 if (worker_maybe_bind_and_lock(worker))
1274 worker_clr_flags(worker, WORKER_REBIND);
1275
1276 spin_unlock_irq(&gcwq->lock);
1277}
1278
1279static struct worker *alloc_worker(void)
1280{
1281 struct worker *worker;
1282
1283 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
1284 if (worker) {
1285 INIT_LIST_HEAD(&worker->entry);
1286 INIT_LIST_HEAD(&worker->scheduled);
1287 INIT_WORK(&worker->rebind_work, worker_rebind_fn);
1288 /* on creation a worker is in !idle && prep state */
1289 worker->flags = WORKER_PREP;
1290 }
1291 return worker;
1292}
1293
1294/**
1295 * create_worker - create a new workqueue worker
1296 * @gcwq: gcwq the new worker will belong to
1297 * @bind: whether to set affinity to @cpu or not
1298 *
1299 * Create a new worker which is bound to @gcwq. The returned worker
1300 * can be started by calling start_worker() or destroyed using
1301 * destroy_worker().
1302 *
1303 * CONTEXT:
1304 * Might sleep. Does GFP_KERNEL allocations.
1305 *
1306 * RETURNS:
1307 * Pointer to the newly created worker.
1308 */
1309static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
1310{
1311 bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND;
1312 struct worker *worker = NULL;
1313 int id = -1;
1314
1315 spin_lock_irq(&gcwq->lock);
1316 while (ida_get_new(&gcwq->worker_ida, &id)) {
1317 spin_unlock_irq(&gcwq->lock);
1318 if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL))
1319 goto fail;
1320 spin_lock_irq(&gcwq->lock);
1321 }
1322 spin_unlock_irq(&gcwq->lock);
1323
1324 worker = alloc_worker();
1325 if (!worker)
1326 goto fail;
1327
1328 worker->gcwq = gcwq;
1329 worker->id = id;
1330
1331 if (!on_unbound_cpu)
1332 worker->task = kthread_create(worker_thread, worker,
1333 "kworker/%u:%d", gcwq->cpu, id);
1334 else
1335 worker->task = kthread_create(worker_thread, worker,
1336 "kworker/u:%d", id);
1337 if (IS_ERR(worker->task))
1338 goto fail;
1339
1340 /*
1341 * A rogue worker will become a regular one if CPU comes
1342 * online later on. Make sure every worker has
1343 * PF_THREAD_BOUND set.
1344 */
1345 if (bind && !on_unbound_cpu)
1346 kthread_bind(worker->task, gcwq->cpu);
1347 else {
1348 worker->task->flags |= PF_THREAD_BOUND;
1349 if (on_unbound_cpu)
1350 worker->flags |= WORKER_UNBOUND;
1351 }
1352
1353 return worker;
1354fail:
1355 if (id >= 0) {
1356 spin_lock_irq(&gcwq->lock);
1357 ida_remove(&gcwq->worker_ida, id);
1358 spin_unlock_irq(&gcwq->lock);
1359 }
1360 kfree(worker);
1361 return NULL;
1362}
1363
1364/**
1365 * start_worker - start a newly created worker
1366 * @worker: worker to start
1367 *
1368 * Make the gcwq aware of @worker and start it.
1369 *
1370 * CONTEXT:
1371 * spin_lock_irq(gcwq->lock).
1372 */
1373static void start_worker(struct worker *worker)
1374{
1375 worker->flags |= WORKER_STARTED;
1376 worker->gcwq->nr_workers++;
1377 worker_enter_idle(worker);
1378 wake_up_process(worker->task);
1379}
1380
1381/**
1382 * destroy_worker - destroy a workqueue worker
1383 * @worker: worker to be destroyed
1384 *
1385 * Destroy @worker and adjust @gcwq stats accordingly.
1386 *
1387 * CONTEXT:
1388 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1389 */
1390static void destroy_worker(struct worker *worker)
1391{
1392 struct global_cwq *gcwq = worker->gcwq;
1393 int id = worker->id;
1394
1395 /* sanity check frenzy */
1396 BUG_ON(worker->current_work);
1397 BUG_ON(!list_empty(&worker->scheduled));
1398
1399 if (worker->flags & WORKER_STARTED)
1400 gcwq->nr_workers--;
1401 if (worker->flags & WORKER_IDLE)
1402 gcwq->nr_idle--;
1403
1404 list_del_init(&worker->entry);
1405 worker->flags |= WORKER_DIE;
1406
1407 spin_unlock_irq(&gcwq->lock);
1408
1409 kthread_stop(worker->task);
1410 kfree(worker);
1411
1412 spin_lock_irq(&gcwq->lock);
1413 ida_remove(&gcwq->worker_ida, id);
1414}
1415
1416static void idle_worker_timeout(unsigned long __gcwq)
1417{
1418 struct global_cwq *gcwq = (void *)__gcwq;
1419
1420 spin_lock_irq(&gcwq->lock);
1421
1422 if (too_many_workers(gcwq)) {
1423 struct worker *worker;
1424 unsigned long expires;
1425
1426 /* idle_list is kept in LIFO order, check the last one */
1427 worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
1428 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1429
1430 if (time_before(jiffies, expires))
1431 mod_timer(&gcwq->idle_timer, expires);
1432 else {
1433 /* it's been idle for too long, wake up manager */
1434 gcwq->flags |= GCWQ_MANAGE_WORKERS;
1435 wake_up_worker(gcwq);
416 } 1436 }
1437 }
417 1438
418 spin_lock_irq(&cwq->lock); 1439 spin_unlock_irq(&gcwq->lock);
419 cwq->current_work = NULL; 1440}
1441
1442static bool send_mayday(struct work_struct *work)
1443{
1444 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1445 struct workqueue_struct *wq = cwq->wq;
1446 unsigned int cpu;
1447
1448 if (!(wq->flags & WQ_RESCUER))
1449 return false;
1450
1451 /* mayday mayday mayday */
1452 cpu = cwq->gcwq->cpu;
1453 /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
1454 if (cpu == WORK_CPU_UNBOUND)
1455 cpu = 0;
1456 if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask))
1457 wake_up_process(wq->rescuer->task);
1458 return true;
1459}
1460
1461static void gcwq_mayday_timeout(unsigned long __gcwq)
1462{
1463 struct global_cwq *gcwq = (void *)__gcwq;
1464 struct work_struct *work;
1465
1466 spin_lock_irq(&gcwq->lock);
1467
1468 if (need_to_create_worker(gcwq)) {
1469 /*
1470 * We've been trying to create a new worker but
1471 * haven't been successful. We might be hitting an
1472 * allocation deadlock. Send distress signals to
1473 * rescuers.
1474 */
1475 list_for_each_entry(work, &gcwq->worklist, entry)
1476 send_mayday(work);
420 } 1477 }
421 spin_unlock_irq(&cwq->lock); 1478
1479 spin_unlock_irq(&gcwq->lock);
1480
1481 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL);
422} 1482}
423 1483
424static int worker_thread(void *__cwq) 1484/**
1485 * maybe_create_worker - create a new worker if necessary
1486 * @gcwq: gcwq to create a new worker for
1487 *
1488 * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to
1489 * have at least one idle worker on return from this function. If
1490 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1491 * sent to all rescuers with works scheduled on @gcwq to resolve
1492 * possible allocation deadlock.
1493 *
1494 * On return, need_to_create_worker() is guaranteed to be false and
1495 * may_start_working() true.
1496 *
1497 * LOCKING:
1498 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1499 * multiple times. Does GFP_KERNEL allocations. Called only from
1500 * manager.
1501 *
1502 * RETURNS:
1503 * false if no action was taken and gcwq->lock stayed locked, true
1504 * otherwise.
1505 */
1506static bool maybe_create_worker(struct global_cwq *gcwq)
1507__releases(&gcwq->lock)
1508__acquires(&gcwq->lock)
425{ 1509{
426 struct cpu_workqueue_struct *cwq = __cwq; 1510 if (!need_to_create_worker(gcwq))
427 DEFINE_WAIT(wait); 1511 return false;
1512restart:
1513 spin_unlock_irq(&gcwq->lock);
1514
1515 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1516 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
1517
1518 while (true) {
1519 struct worker *worker;
1520
1521 worker = create_worker(gcwq, true);
1522 if (worker) {
1523 del_timer_sync(&gcwq->mayday_timer);
1524 spin_lock_irq(&gcwq->lock);
1525 start_worker(worker);
1526 BUG_ON(need_to_create_worker(gcwq));
1527 return true;
1528 }
1529
1530 if (!need_to_create_worker(gcwq))
1531 break;
1532
1533 __set_current_state(TASK_INTERRUPTIBLE);
1534 schedule_timeout(CREATE_COOLDOWN);
428 1535
429 if (cwq->wq->freezeable) 1536 if (!need_to_create_worker(gcwq))
430 set_freezable(); 1537 break;
1538 }
1539
1540 del_timer_sync(&gcwq->mayday_timer);
1541 spin_lock_irq(&gcwq->lock);
1542 if (need_to_create_worker(gcwq))
1543 goto restart;
1544 return true;
1545}
1546
1547/**
1548 * maybe_destroy_worker - destroy workers which have been idle for a while
1549 * @gcwq: gcwq to destroy workers for
1550 *
1551 * Destroy @gcwq workers which have been idle for longer than
1552 * IDLE_WORKER_TIMEOUT.
1553 *
1554 * LOCKING:
1555 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1556 * multiple times. Called only from manager.
1557 *
1558 * RETURNS:
1559 * false if no action was taken and gcwq->lock stayed locked, true
1560 * otherwise.
1561 */
1562static bool maybe_destroy_workers(struct global_cwq *gcwq)
1563{
1564 bool ret = false;
431 1565
432 for (;;) { 1566 while (too_many_workers(gcwq)) {
433 prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE); 1567 struct worker *worker;
434 if (!freezing(current) && 1568 unsigned long expires;
435 !kthread_should_stop() &&
436 list_empty(&cwq->worklist))
437 schedule();
438 finish_wait(&cwq->more_work, &wait);
439 1569
440 try_to_freeze(); 1570 worker = list_entry(gcwq->idle_list.prev, struct worker, entry);
1571 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
441 1572
442 if (kthread_should_stop()) 1573 if (time_before(jiffies, expires)) {
1574 mod_timer(&gcwq->idle_timer, expires);
443 break; 1575 break;
1576 }
444 1577
445 run_workqueue(cwq); 1578 destroy_worker(worker);
1579 ret = true;
446 } 1580 }
447 1581
448 return 0; 1582 return ret;
1583}
1584
1585/**
1586 * manage_workers - manage worker pool
1587 * @worker: self
1588 *
1589 * Assume the manager role and manage gcwq worker pool @worker belongs
1590 * to. At any given time, there can be only zero or one manager per
1591 * gcwq. The exclusion is handled automatically by this function.
1592 *
1593 * The caller can safely start processing works on false return. On
1594 * true return, it's guaranteed that need_to_create_worker() is false
1595 * and may_start_working() is true.
1596 *
1597 * CONTEXT:
1598 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1599 * multiple times. Does GFP_KERNEL allocations.
1600 *
1601 * RETURNS:
1602 * false if no action was taken and gcwq->lock stayed locked, true if
1603 * some action was taken.
1604 */
1605static bool manage_workers(struct worker *worker)
1606{
1607 struct global_cwq *gcwq = worker->gcwq;
1608 bool ret = false;
1609
1610 if (gcwq->flags & GCWQ_MANAGING_WORKERS)
1611 return ret;
1612
1613 gcwq->flags &= ~GCWQ_MANAGE_WORKERS;
1614 gcwq->flags |= GCWQ_MANAGING_WORKERS;
1615
1616 /*
1617 * Destroy and then create so that may_start_working() is true
1618 * on return.
1619 */
1620 ret |= maybe_destroy_workers(gcwq);
1621 ret |= maybe_create_worker(gcwq);
1622
1623 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
1624
1625 /*
1626 * The trustee might be waiting to take over the manager
1627 * position, tell it we're done.
1628 */
1629 if (unlikely(gcwq->trustee))
1630 wake_up_all(&gcwq->trustee_wait);
1631
1632 return ret;
1633}
1634
1635/**
1636 * move_linked_works - move linked works to a list
1637 * @work: start of series of works to be scheduled
1638 * @head: target list to append @work to
1639 * @nextp: out paramter for nested worklist walking
1640 *
1641 * Schedule linked works starting from @work to @head. Work series to
1642 * be scheduled starts at @work and includes any consecutive work with
1643 * WORK_STRUCT_LINKED set in its predecessor.
1644 *
1645 * If @nextp is not NULL, it's updated to point to the next work of
1646 * the last scheduled work. This allows move_linked_works() to be
1647 * nested inside outer list_for_each_entry_safe().
1648 *
1649 * CONTEXT:
1650 * spin_lock_irq(gcwq->lock).
1651 */
1652static void move_linked_works(struct work_struct *work, struct list_head *head,
1653 struct work_struct **nextp)
1654{
1655 struct work_struct *n;
1656
1657 /*
1658 * Linked worklist will always end before the end of the list,
1659 * use NULL for list head.
1660 */
1661 list_for_each_entry_safe_from(work, n, NULL, entry) {
1662 list_move_tail(&work->entry, head);
1663 if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1664 break;
1665 }
1666
1667 /*
1668 * If we're already inside safe list traversal and have moved
1669 * multiple works to the scheduled queue, the next position
1670 * needs to be updated.
1671 */
1672 if (nextp)
1673 *nextp = n;
1674}
1675
1676static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
1677{
1678 struct work_struct *work = list_first_entry(&cwq->delayed_works,
1679 struct work_struct, entry);
1680 struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
1681
1682 move_linked_works(work, pos, NULL);
1683 __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
1684 cwq->nr_active++;
1685}
1686
1687/**
1688 * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
1689 * @cwq: cwq of interest
1690 * @color: color of work which left the queue
1691 * @delayed: for a delayed work
1692 *
1693 * A work either has completed or is removed from pending queue,
1694 * decrement nr_in_flight of its cwq and handle workqueue flushing.
1695 *
1696 * CONTEXT:
1697 * spin_lock_irq(gcwq->lock).
1698 */
1699static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color,
1700 bool delayed)
1701{
1702 /* ignore uncolored works */
1703 if (color == WORK_NO_COLOR)
1704 return;
1705
1706 cwq->nr_in_flight[color]--;
1707
1708 if (!delayed) {
1709 cwq->nr_active--;
1710 if (!list_empty(&cwq->delayed_works)) {
1711 /* one down, submit a delayed one */
1712 if (cwq->nr_active < cwq->max_active)
1713 cwq_activate_first_delayed(cwq);
1714 }
1715 }
1716
1717 /* is flush in progress and are we at the flushing tip? */
1718 if (likely(cwq->flush_color != color))
1719 return;
1720
1721 /* are there still in-flight works? */
1722 if (cwq->nr_in_flight[color])
1723 return;
1724
1725 /* this cwq is done, clear flush_color */
1726 cwq->flush_color = -1;
1727
1728 /*
1729 * If this was the last cwq, wake up the first flusher. It
1730 * will handle the rest.
1731 */
1732 if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
1733 complete(&cwq->wq->first_flusher->done);
1734}
1735
1736/**
1737 * process_one_work - process single work
1738 * @worker: self
1739 * @work: work to process
1740 *
1741 * Process @work. This function contains all the logics necessary to
1742 * process a single work including synchronization against and
1743 * interaction with other workers on the same cpu, queueing and
1744 * flushing. As long as context requirement is met, any worker can
1745 * call this function to process a work.
1746 *
1747 * CONTEXT:
1748 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1749 */
1750static void process_one_work(struct worker *worker, struct work_struct *work)
1751__releases(&gcwq->lock)
1752__acquires(&gcwq->lock)
1753{
1754 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1755 struct global_cwq *gcwq = cwq->gcwq;
1756 struct hlist_head *bwh = busy_worker_head(gcwq, work);
1757 bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
1758 work_func_t f = work->func;
1759 int work_color;
1760 struct worker *collision;
1761#ifdef CONFIG_LOCKDEP
1762 /*
1763 * It is permissible to free the struct work_struct from
1764 * inside the function that is called from it, this we need to
1765 * take into account for lockdep too. To avoid bogus "held
1766 * lock freed" warnings as well as problems when looking into
1767 * work->lockdep_map, make a copy and use that here.
1768 */
1769 struct lockdep_map lockdep_map = work->lockdep_map;
1770#endif
1771 /*
1772 * A single work shouldn't be executed concurrently by
1773 * multiple workers on a single cpu. Check whether anyone is
1774 * already processing the work. If so, defer the work to the
1775 * currently executing one.
1776 */
1777 collision = __find_worker_executing_work(gcwq, bwh, work);
1778 if (unlikely(collision)) {
1779 move_linked_works(work, &collision->scheduled, NULL);
1780 return;
1781 }
1782
1783 /* claim and process */
1784 debug_work_deactivate(work);
1785 hlist_add_head(&worker->hentry, bwh);
1786 worker->current_work = work;
1787 worker->current_cwq = cwq;
1788 work_color = get_work_color(work);
1789
1790 /* record the current cpu number in the work data and dequeue */
1791 set_work_cpu(work, gcwq->cpu);
1792 list_del_init(&work->entry);
1793
1794 /*
1795 * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI,
1796 * wake up another worker; otherwise, clear HIGHPRI_PENDING.
1797 */
1798 if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) {
1799 struct work_struct *nwork = list_first_entry(&gcwq->worklist,
1800 struct work_struct, entry);
1801
1802 if (!list_empty(&gcwq->worklist) &&
1803 get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI)
1804 wake_up_worker(gcwq);
1805 else
1806 gcwq->flags &= ~GCWQ_HIGHPRI_PENDING;
1807 }
1808
1809 /*
1810 * CPU intensive works don't participate in concurrency
1811 * management. They're the scheduler's responsibility.
1812 */
1813 if (unlikely(cpu_intensive))
1814 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
1815
1816 spin_unlock_irq(&gcwq->lock);
1817
1818 work_clear_pending(work);
1819 lock_map_acquire(&cwq->wq->lockdep_map);
1820 lock_map_acquire(&lockdep_map);
1821 trace_workqueue_execute_start(work);
1822 f(work);
1823 /*
1824 * While we must be careful to not use "work" after this, the trace
1825 * point will only record its address.
1826 */
1827 trace_workqueue_execute_end(work);
1828 lock_map_release(&lockdep_map);
1829 lock_map_release(&cwq->wq->lockdep_map);
1830
1831 if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
1832 printk(KERN_ERR "BUG: workqueue leaked lock or atomic: "
1833 "%s/0x%08x/%d\n",
1834 current->comm, preempt_count(), task_pid_nr(current));
1835 printk(KERN_ERR " last function: ");
1836 print_symbol("%s\n", (unsigned long)f);
1837 debug_show_held_locks(current);
1838 dump_stack();
1839 }
1840
1841 spin_lock_irq(&gcwq->lock);
1842
1843 /* clear cpu intensive status */
1844 if (unlikely(cpu_intensive))
1845 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
1846
1847 /* we're done with it, release */
1848 hlist_del_init(&worker->hentry);
1849 worker->current_work = NULL;
1850 worker->current_cwq = NULL;
1851 cwq_dec_nr_in_flight(cwq, work_color, false);
1852}
1853
1854/**
1855 * process_scheduled_works - process scheduled works
1856 * @worker: self
1857 *
1858 * Process all scheduled works. Please note that the scheduled list
1859 * may change while processing a work, so this function repeatedly
1860 * fetches a work from the top and executes it.
1861 *
1862 * CONTEXT:
1863 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1864 * multiple times.
1865 */
1866static void process_scheduled_works(struct worker *worker)
1867{
1868 while (!list_empty(&worker->scheduled)) {
1869 struct work_struct *work = list_first_entry(&worker->scheduled,
1870 struct work_struct, entry);
1871 process_one_work(worker, work);
1872 }
1873}
1874
1875/**
1876 * worker_thread - the worker thread function
1877 * @__worker: self
1878 *
1879 * The gcwq worker thread function. There's a single dynamic pool of
1880 * these per each cpu. These workers process all works regardless of
1881 * their specific target workqueue. The only exception is works which
1882 * belong to workqueues with a rescuer which will be explained in
1883 * rescuer_thread().
1884 */
1885static int worker_thread(void *__worker)
1886{
1887 struct worker *worker = __worker;
1888 struct global_cwq *gcwq = worker->gcwq;
1889
1890 /* tell the scheduler that this is a workqueue worker */
1891 worker->task->flags |= PF_WQ_WORKER;
1892woke_up:
1893 spin_lock_irq(&gcwq->lock);
1894
1895 /* DIE can be set only while we're idle, checking here is enough */
1896 if (worker->flags & WORKER_DIE) {
1897 spin_unlock_irq(&gcwq->lock);
1898 worker->task->flags &= ~PF_WQ_WORKER;
1899 return 0;
1900 }
1901
1902 worker_leave_idle(worker);
1903recheck:
1904 /* no more worker necessary? */
1905 if (!need_more_worker(gcwq))
1906 goto sleep;
1907
1908 /* do we need to manage? */
1909 if (unlikely(!may_start_working(gcwq)) && manage_workers(worker))
1910 goto recheck;
1911
1912 /*
1913 * ->scheduled list can only be filled while a worker is
1914 * preparing to process a work or actually processing it.
1915 * Make sure nobody diddled with it while I was sleeping.
1916 */
1917 BUG_ON(!list_empty(&worker->scheduled));
1918
1919 /*
1920 * When control reaches this point, we're guaranteed to have
1921 * at least one idle worker or that someone else has already
1922 * assumed the manager role.
1923 */
1924 worker_clr_flags(worker, WORKER_PREP);
1925
1926 do {
1927 struct work_struct *work =
1928 list_first_entry(&gcwq->worklist,
1929 struct work_struct, entry);
1930
1931 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
1932 /* optimization path, not strictly necessary */
1933 process_one_work(worker, work);
1934 if (unlikely(!list_empty(&worker->scheduled)))
1935 process_scheduled_works(worker);
1936 } else {
1937 move_linked_works(work, &worker->scheduled, NULL);
1938 process_scheduled_works(worker);
1939 }
1940 } while (keep_working(gcwq));
1941
1942 worker_set_flags(worker, WORKER_PREP, false);
1943sleep:
1944 if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker))
1945 goto recheck;
1946
1947 /*
1948 * gcwq->lock is held and there's no work to process and no
1949 * need to manage, sleep. Workers are woken up only while
1950 * holding gcwq->lock or from local cpu, so setting the
1951 * current state before releasing gcwq->lock is enough to
1952 * prevent losing any event.
1953 */
1954 worker_enter_idle(worker);
1955 __set_current_state(TASK_INTERRUPTIBLE);
1956 spin_unlock_irq(&gcwq->lock);
1957 schedule();
1958 goto woke_up;
1959}
1960
1961/**
1962 * rescuer_thread - the rescuer thread function
1963 * @__wq: the associated workqueue
1964 *
1965 * Workqueue rescuer thread function. There's one rescuer for each
1966 * workqueue which has WQ_RESCUER set.
1967 *
1968 * Regular work processing on a gcwq may block trying to create a new
1969 * worker which uses GFP_KERNEL allocation which has slight chance of
1970 * developing into deadlock if some works currently on the same queue
1971 * need to be processed to satisfy the GFP_KERNEL allocation. This is
1972 * the problem rescuer solves.
1973 *
1974 * When such condition is possible, the gcwq summons rescuers of all
1975 * workqueues which have works queued on the gcwq and let them process
1976 * those works so that forward progress can be guaranteed.
1977 *
1978 * This should happen rarely.
1979 */
1980static int rescuer_thread(void *__wq)
1981{
1982 struct workqueue_struct *wq = __wq;
1983 struct worker *rescuer = wq->rescuer;
1984 struct list_head *scheduled = &rescuer->scheduled;
1985 bool is_unbound = wq->flags & WQ_UNBOUND;
1986 unsigned int cpu;
1987
1988 set_user_nice(current, RESCUER_NICE_LEVEL);
1989repeat:
1990 set_current_state(TASK_INTERRUPTIBLE);
1991
1992 if (kthread_should_stop())
1993 return 0;
1994
1995 /*
1996 * See whether any cpu is asking for help. Unbounded
1997 * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
1998 */
1999 for_each_mayday_cpu(cpu, wq->mayday_mask) {
2000 unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
2001 struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
2002 struct global_cwq *gcwq = cwq->gcwq;
2003 struct work_struct *work, *n;
2004
2005 __set_current_state(TASK_RUNNING);
2006 mayday_clear_cpu(cpu, wq->mayday_mask);
2007
2008 /* migrate to the target cpu if possible */
2009 rescuer->gcwq = gcwq;
2010 worker_maybe_bind_and_lock(rescuer);
2011
2012 /*
2013 * Slurp in all works issued via this workqueue and
2014 * process'em.
2015 */
2016 BUG_ON(!list_empty(&rescuer->scheduled));
2017 list_for_each_entry_safe(work, n, &gcwq->worklist, entry)
2018 if (get_work_cwq(work) == cwq)
2019 move_linked_works(work, scheduled, &n);
2020
2021 process_scheduled_works(rescuer);
2022 spin_unlock_irq(&gcwq->lock);
2023 }
2024
2025 schedule();
2026 goto repeat;
449} 2027}
450 2028
451struct wq_barrier { 2029struct wq_barrier {
@@ -459,44 +2037,137 @@ static void wq_barrier_func(struct work_struct *work)
459 complete(&barr->done); 2037 complete(&barr->done);
460} 2038}
461 2039
2040/**
2041 * insert_wq_barrier - insert a barrier work
2042 * @cwq: cwq to insert barrier into
2043 * @barr: wq_barrier to insert
2044 * @target: target work to attach @barr to
2045 * @worker: worker currently executing @target, NULL if @target is not executing
2046 *
2047 * @barr is linked to @target such that @barr is completed only after
2048 * @target finishes execution. Please note that the ordering
2049 * guarantee is observed only with respect to @target and on the local
2050 * cpu.
2051 *
2052 * Currently, a queued barrier can't be canceled. This is because
2053 * try_to_grab_pending() can't determine whether the work to be
2054 * grabbed is at the head of the queue and thus can't clear LINKED
2055 * flag of the previous work while there must be a valid next work
2056 * after a work with LINKED flag set.
2057 *
2058 * Note that when @worker is non-NULL, @target may be modified
2059 * underneath us, so we can't reliably determine cwq from @target.
2060 *
2061 * CONTEXT:
2062 * spin_lock_irq(gcwq->lock).
2063 */
462static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, 2064static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
463 struct wq_barrier *barr, struct list_head *head) 2065 struct wq_barrier *barr,
2066 struct work_struct *target, struct worker *worker)
464{ 2067{
2068 struct list_head *head;
2069 unsigned int linked = 0;
2070
465 /* 2071 /*
466 * debugobject calls are safe here even with cwq->lock locked 2072 * debugobject calls are safe here even with gcwq->lock locked
467 * as we know for sure that this will not trigger any of the 2073 * as we know for sure that this will not trigger any of the
468 * checks and call back into the fixup functions where we 2074 * checks and call back into the fixup functions where we
469 * might deadlock. 2075 * might deadlock.
470 */ 2076 */
471 INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); 2077 INIT_WORK_ON_STACK(&barr->work, wq_barrier_func);
472 __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work)); 2078 __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
473
474 init_completion(&barr->done); 2079 init_completion(&barr->done);
475 2080
2081 /*
2082 * If @target is currently being executed, schedule the
2083 * barrier to the worker; otherwise, put it after @target.
2084 */
2085 if (worker)
2086 head = worker->scheduled.next;
2087 else {
2088 unsigned long *bits = work_data_bits(target);
2089
2090 head = target->entry.next;
2091 /* there can already be other linked works, inherit and set */
2092 linked = *bits & WORK_STRUCT_LINKED;
2093 __set_bit(WORK_STRUCT_LINKED_BIT, bits);
2094 }
2095
476 debug_work_activate(&barr->work); 2096 debug_work_activate(&barr->work);
477 insert_work(cwq, &barr->work, head); 2097 insert_work(cwq, &barr->work, head,
2098 work_color_to_flags(WORK_NO_COLOR) | linked);
478} 2099}
479 2100
480static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) 2101/**
2102 * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
2103 * @wq: workqueue being flushed
2104 * @flush_color: new flush color, < 0 for no-op
2105 * @work_color: new work color, < 0 for no-op
2106 *
2107 * Prepare cwqs for workqueue flushing.
2108 *
2109 * If @flush_color is non-negative, flush_color on all cwqs should be
2110 * -1. If no cwq has in-flight commands at the specified color, all
2111 * cwq->flush_color's stay at -1 and %false is returned. If any cwq
2112 * has in flight commands, its cwq->flush_color is set to
2113 * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
2114 * wakeup logic is armed and %true is returned.
2115 *
2116 * The caller should have initialized @wq->first_flusher prior to
2117 * calling this function with non-negative @flush_color. If
2118 * @flush_color is negative, no flush color update is done and %false
2119 * is returned.
2120 *
2121 * If @work_color is non-negative, all cwqs should have the same
2122 * work_color which is previous to @work_color and all will be
2123 * advanced to @work_color.
2124 *
2125 * CONTEXT:
2126 * mutex_lock(wq->flush_mutex).
2127 *
2128 * RETURNS:
2129 * %true if @flush_color >= 0 and there's something to flush. %false
2130 * otherwise.
2131 */
2132static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
2133 int flush_color, int work_color)
481{ 2134{
482 int active = 0; 2135 bool wait = false;
483 struct wq_barrier barr; 2136 unsigned int cpu;
484
485 WARN_ON(cwq->thread == current);
486 2137
487 spin_lock_irq(&cwq->lock); 2138 if (flush_color >= 0) {
488 if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) { 2139 BUG_ON(atomic_read(&wq->nr_cwqs_to_flush));
489 insert_wq_barrier(cwq, &barr, &cwq->worklist); 2140 atomic_set(&wq->nr_cwqs_to_flush, 1);
490 active = 1;
491 } 2141 }
492 spin_unlock_irq(&cwq->lock);
493 2142
494 if (active) { 2143 for_each_cwq_cpu(cpu, wq) {
495 wait_for_completion(&barr.done); 2144 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
496 destroy_work_on_stack(&barr.work); 2145 struct global_cwq *gcwq = cwq->gcwq;
2146
2147 spin_lock_irq(&gcwq->lock);
2148
2149 if (flush_color >= 0) {
2150 BUG_ON(cwq->flush_color != -1);
2151
2152 if (cwq->nr_in_flight[flush_color]) {
2153 cwq->flush_color = flush_color;
2154 atomic_inc(&wq->nr_cwqs_to_flush);
2155 wait = true;
2156 }
2157 }
2158
2159 if (work_color >= 0) {
2160 BUG_ON(work_color != work_next_color(cwq->work_color));
2161 cwq->work_color = work_color;
2162 }
2163
2164 spin_unlock_irq(&gcwq->lock);
497 } 2165 }
498 2166
499 return active; 2167 if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush))
2168 complete(&wq->first_flusher->done);
2169
2170 return wait;
500} 2171}
501 2172
502/** 2173/**
@@ -508,20 +2179,150 @@ static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
508 * 2179 *
509 * We sleep until all works which were queued on entry have been handled, 2180 * We sleep until all works which were queued on entry have been handled,
510 * but we are not livelocked by new incoming ones. 2181 * but we are not livelocked by new incoming ones.
511 *
512 * This function used to run the workqueues itself. Now we just wait for the
513 * helper threads to do it.
514 */ 2182 */
515void flush_workqueue(struct workqueue_struct *wq) 2183void flush_workqueue(struct workqueue_struct *wq)
516{ 2184{
517 const struct cpumask *cpu_map = wq_cpu_map(wq); 2185 struct wq_flusher this_flusher = {
518 int cpu; 2186 .list = LIST_HEAD_INIT(this_flusher.list),
2187 .flush_color = -1,
2188 .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done),
2189 };
2190 int next_color;
519 2191
520 might_sleep();
521 lock_map_acquire(&wq->lockdep_map); 2192 lock_map_acquire(&wq->lockdep_map);
522 lock_map_release(&wq->lockdep_map); 2193 lock_map_release(&wq->lockdep_map);
523 for_each_cpu(cpu, cpu_map) 2194
524 flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu)); 2195 mutex_lock(&wq->flush_mutex);
2196
2197 /*
2198 * Start-to-wait phase
2199 */
2200 next_color = work_next_color(wq->work_color);
2201
2202 if (next_color != wq->flush_color) {
2203 /*
2204 * Color space is not full. The current work_color
2205 * becomes our flush_color and work_color is advanced
2206 * by one.
2207 */
2208 BUG_ON(!list_empty(&wq->flusher_overflow));
2209 this_flusher.flush_color = wq->work_color;
2210 wq->work_color = next_color;
2211
2212 if (!wq->first_flusher) {
2213 /* no flush in progress, become the first flusher */
2214 BUG_ON(wq->flush_color != this_flusher.flush_color);
2215
2216 wq->first_flusher = &this_flusher;
2217
2218 if (!flush_workqueue_prep_cwqs(wq, wq->flush_color,
2219 wq->work_color)) {
2220 /* nothing to flush, done */
2221 wq->flush_color = next_color;
2222 wq->first_flusher = NULL;
2223 goto out_unlock;
2224 }
2225 } else {
2226 /* wait in queue */
2227 BUG_ON(wq->flush_color == this_flusher.flush_color);
2228 list_add_tail(&this_flusher.list, &wq->flusher_queue);
2229 flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
2230 }
2231 } else {
2232 /*
2233 * Oops, color space is full, wait on overflow queue.
2234 * The next flush completion will assign us
2235 * flush_color and transfer to flusher_queue.
2236 */
2237 list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2238 }
2239
2240 mutex_unlock(&wq->flush_mutex);
2241
2242 wait_for_completion(&this_flusher.done);
2243
2244 /*
2245 * Wake-up-and-cascade phase
2246 *
2247 * First flushers are responsible for cascading flushes and
2248 * handling overflow. Non-first flushers can simply return.
2249 */
2250 if (wq->first_flusher != &this_flusher)
2251 return;
2252
2253 mutex_lock(&wq->flush_mutex);
2254
2255 /* we might have raced, check again with mutex held */
2256 if (wq->first_flusher != &this_flusher)
2257 goto out_unlock;
2258
2259 wq->first_flusher = NULL;
2260
2261 BUG_ON(!list_empty(&this_flusher.list));
2262 BUG_ON(wq->flush_color != this_flusher.flush_color);
2263
2264 while (true) {
2265 struct wq_flusher *next, *tmp;
2266
2267 /* complete all the flushers sharing the current flush color */
2268 list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2269 if (next->flush_color != wq->flush_color)
2270 break;
2271 list_del_init(&next->list);
2272 complete(&next->done);
2273 }
2274
2275 BUG_ON(!list_empty(&wq->flusher_overflow) &&
2276 wq->flush_color != work_next_color(wq->work_color));
2277
2278 /* this flush_color is finished, advance by one */
2279 wq->flush_color = work_next_color(wq->flush_color);
2280
2281 /* one color has been freed, handle overflow queue */
2282 if (!list_empty(&wq->flusher_overflow)) {
2283 /*
2284 * Assign the same color to all overflowed
2285 * flushers, advance work_color and append to
2286 * flusher_queue. This is the start-to-wait
2287 * phase for these overflowed flushers.
2288 */
2289 list_for_each_entry(tmp, &wq->flusher_overflow, list)
2290 tmp->flush_color = wq->work_color;
2291
2292 wq->work_color = work_next_color(wq->work_color);
2293
2294 list_splice_tail_init(&wq->flusher_overflow,
2295 &wq->flusher_queue);
2296 flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
2297 }
2298
2299 if (list_empty(&wq->flusher_queue)) {
2300 BUG_ON(wq->flush_color != wq->work_color);
2301 break;
2302 }
2303
2304 /*
2305 * Need to flush more colors. Make the next flusher
2306 * the new first flusher and arm cwqs.
2307 */
2308 BUG_ON(wq->flush_color == wq->work_color);
2309 BUG_ON(wq->flush_color != next->flush_color);
2310
2311 list_del_init(&next->list);
2312 wq->first_flusher = next;
2313
2314 if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1))
2315 break;
2316
2317 /*
2318 * Meh... this color is already done, clear first
2319 * flusher and repeat cascading.
2320 */
2321 wq->first_flusher = NULL;
2322 }
2323
2324out_unlock:
2325 mutex_unlock(&wq->flush_mutex);
525} 2326}
526EXPORT_SYMBOL_GPL(flush_workqueue); 2327EXPORT_SYMBOL_GPL(flush_workqueue);
527 2328
@@ -537,43 +2338,46 @@ EXPORT_SYMBOL_GPL(flush_workqueue);
537 */ 2338 */
538int flush_work(struct work_struct *work) 2339int flush_work(struct work_struct *work)
539{ 2340{
2341 struct worker *worker = NULL;
2342 struct global_cwq *gcwq;
540 struct cpu_workqueue_struct *cwq; 2343 struct cpu_workqueue_struct *cwq;
541 struct list_head *prev;
542 struct wq_barrier barr; 2344 struct wq_barrier barr;
543 2345
544 might_sleep(); 2346 might_sleep();
545 cwq = get_wq_data(work); 2347 gcwq = get_work_gcwq(work);
546 if (!cwq) 2348 if (!gcwq)
547 return 0; 2349 return 0;
548 2350
549 lock_map_acquire(&cwq->wq->lockdep_map); 2351 spin_lock_irq(&gcwq->lock);
550 lock_map_release(&cwq->wq->lockdep_map);
551
552 prev = NULL;
553 spin_lock_irq(&cwq->lock);
554 if (!list_empty(&work->entry)) { 2352 if (!list_empty(&work->entry)) {
555 /* 2353 /*
556 * See the comment near try_to_grab_pending()->smp_rmb(). 2354 * See the comment near try_to_grab_pending()->smp_rmb().
557 * If it was re-queued under us we are not going to wait. 2355 * If it was re-queued to a different gcwq under us, we
2356 * are not going to wait.
558 */ 2357 */
559 smp_rmb(); 2358 smp_rmb();
560 if (unlikely(cwq != get_wq_data(work))) 2359 cwq = get_work_cwq(work);
561 goto out; 2360 if (unlikely(!cwq || gcwq != cwq->gcwq))
562 prev = &work->entry; 2361 goto already_gone;
563 } else { 2362 } else {
564 if (cwq->current_work != work) 2363 worker = find_worker_executing_work(gcwq, work);
565 goto out; 2364 if (!worker)
566 prev = &cwq->worklist; 2365 goto already_gone;
2366 cwq = worker->current_cwq;
567 } 2367 }
568 insert_wq_barrier(cwq, &barr, prev->next); 2368
569out: 2369 insert_wq_barrier(cwq, &barr, work, worker);
570 spin_unlock_irq(&cwq->lock); 2370 spin_unlock_irq(&gcwq->lock);
571 if (!prev) 2371
572 return 0; 2372 lock_map_acquire(&cwq->wq->lockdep_map);
2373 lock_map_release(&cwq->wq->lockdep_map);
573 2374
574 wait_for_completion(&barr.done); 2375 wait_for_completion(&barr.done);
575 destroy_work_on_stack(&barr.work); 2376 destroy_work_on_stack(&barr.work);
576 return 1; 2377 return 1;
2378already_gone:
2379 spin_unlock_irq(&gcwq->lock);
2380 return 0;
577} 2381}
578EXPORT_SYMBOL_GPL(flush_work); 2382EXPORT_SYMBOL_GPL(flush_work);
579 2383
@@ -583,54 +2387,56 @@ EXPORT_SYMBOL_GPL(flush_work);
583 */ 2387 */
584static int try_to_grab_pending(struct work_struct *work) 2388static int try_to_grab_pending(struct work_struct *work)
585{ 2389{
586 struct cpu_workqueue_struct *cwq; 2390 struct global_cwq *gcwq;
587 int ret = -1; 2391 int ret = -1;
588 2392
589 if (!test_and_set_bit(WORK_STRUCT_PENDING, work_data_bits(work))) 2393 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
590 return 0; 2394 return 0;
591 2395
592 /* 2396 /*
593 * The queueing is in progress, or it is already queued. Try to 2397 * The queueing is in progress, or it is already queued. Try to
594 * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 2398 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
595 */ 2399 */
596 2400 gcwq = get_work_gcwq(work);
597 cwq = get_wq_data(work); 2401 if (!gcwq)
598 if (!cwq)
599 return ret; 2402 return ret;
600 2403
601 spin_lock_irq(&cwq->lock); 2404 spin_lock_irq(&gcwq->lock);
602 if (!list_empty(&work->entry)) { 2405 if (!list_empty(&work->entry)) {
603 /* 2406 /*
604 * This work is queued, but perhaps we locked the wrong cwq. 2407 * This work is queued, but perhaps we locked the wrong gcwq.
605 * In that case we must see the new value after rmb(), see 2408 * In that case we must see the new value after rmb(), see
606 * insert_work()->wmb(). 2409 * insert_work()->wmb().
607 */ 2410 */
608 smp_rmb(); 2411 smp_rmb();
609 if (cwq == get_wq_data(work)) { 2412 if (gcwq == get_work_gcwq(work)) {
610 debug_work_deactivate(work); 2413 debug_work_deactivate(work);
611 list_del_init(&work->entry); 2414 list_del_init(&work->entry);
2415 cwq_dec_nr_in_flight(get_work_cwq(work),
2416 get_work_color(work),
2417 *work_data_bits(work) & WORK_STRUCT_DELAYED);
612 ret = 1; 2418 ret = 1;
613 } 2419 }
614 } 2420 }
615 spin_unlock_irq(&cwq->lock); 2421 spin_unlock_irq(&gcwq->lock);
616 2422
617 return ret; 2423 return ret;
618} 2424}
619 2425
620static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, 2426static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work)
621 struct work_struct *work)
622{ 2427{
623 struct wq_barrier barr; 2428 struct wq_barrier barr;
624 int running = 0; 2429 struct worker *worker;
625 2430
626 spin_lock_irq(&cwq->lock); 2431 spin_lock_irq(&gcwq->lock);
627 if (unlikely(cwq->current_work == work)) { 2432
628 insert_wq_barrier(cwq, &barr, cwq->worklist.next); 2433 worker = find_worker_executing_work(gcwq, work);
629 running = 1; 2434 if (unlikely(worker))
630 } 2435 insert_wq_barrier(worker->current_cwq, &barr, work, worker);
631 spin_unlock_irq(&cwq->lock);
632 2436
633 if (unlikely(running)) { 2437 spin_unlock_irq(&gcwq->lock);
2438
2439 if (unlikely(worker)) {
634 wait_for_completion(&barr.done); 2440 wait_for_completion(&barr.done);
635 destroy_work_on_stack(&barr.work); 2441 destroy_work_on_stack(&barr.work);
636 } 2442 }
@@ -638,9 +2444,6 @@ static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
638 2444
639static void wait_on_work(struct work_struct *work) 2445static void wait_on_work(struct work_struct *work)
640{ 2446{
641 struct cpu_workqueue_struct *cwq;
642 struct workqueue_struct *wq;
643 const struct cpumask *cpu_map;
644 int cpu; 2447 int cpu;
645 2448
646 might_sleep(); 2449 might_sleep();
@@ -648,15 +2451,8 @@ static void wait_on_work(struct work_struct *work)
648 lock_map_acquire(&work->lockdep_map); 2451 lock_map_acquire(&work->lockdep_map);
649 lock_map_release(&work->lockdep_map); 2452 lock_map_release(&work->lockdep_map);
650 2453
651 cwq = get_wq_data(work); 2454 for_each_gcwq_cpu(cpu)
652 if (!cwq) 2455 wait_on_cpu_work(get_gcwq(cpu), work);
653 return;
654
655 wq = cwq->wq;
656 cpu_map = wq_cpu_map(wq);
657
658 for_each_cpu(cpu, cpu_map)
659 wait_on_cpu_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
660} 2456}
661 2457
662static int __cancel_work_timer(struct work_struct *work, 2458static int __cancel_work_timer(struct work_struct *work,
@@ -671,7 +2467,7 @@ static int __cancel_work_timer(struct work_struct *work,
671 wait_on_work(work); 2467 wait_on_work(work);
672 } while (unlikely(ret < 0)); 2468 } while (unlikely(ret < 0));
673 2469
674 work_clear_pending(work); 2470 clear_work_data(work);
675 return ret; 2471 return ret;
676} 2472}
677 2473
@@ -717,8 +2513,6 @@ int cancel_delayed_work_sync(struct delayed_work *dwork)
717} 2513}
718EXPORT_SYMBOL(cancel_delayed_work_sync); 2514EXPORT_SYMBOL(cancel_delayed_work_sync);
719 2515
720static struct workqueue_struct *keventd_wq __read_mostly;
721
722/** 2516/**
723 * schedule_work - put work task in global workqueue 2517 * schedule_work - put work task in global workqueue
724 * @work: job to be done 2518 * @work: job to be done
@@ -732,7 +2526,7 @@ static struct workqueue_struct *keventd_wq __read_mostly;
732 */ 2526 */
733int schedule_work(struct work_struct *work) 2527int schedule_work(struct work_struct *work)
734{ 2528{
735 return queue_work(keventd_wq, work); 2529 return queue_work(system_wq, work);
736} 2530}
737EXPORT_SYMBOL(schedule_work); 2531EXPORT_SYMBOL(schedule_work);
738 2532
@@ -745,7 +2539,7 @@ EXPORT_SYMBOL(schedule_work);
745 */ 2539 */
746int schedule_work_on(int cpu, struct work_struct *work) 2540int schedule_work_on(int cpu, struct work_struct *work)
747{ 2541{
748 return queue_work_on(cpu, keventd_wq, work); 2542 return queue_work_on(cpu, system_wq, work);
749} 2543}
750EXPORT_SYMBOL(schedule_work_on); 2544EXPORT_SYMBOL(schedule_work_on);
751 2545
@@ -760,7 +2554,7 @@ EXPORT_SYMBOL(schedule_work_on);
760int schedule_delayed_work(struct delayed_work *dwork, 2554int schedule_delayed_work(struct delayed_work *dwork,
761 unsigned long delay) 2555 unsigned long delay)
762{ 2556{
763 return queue_delayed_work(keventd_wq, dwork, delay); 2557 return queue_delayed_work(system_wq, dwork, delay);
764} 2558}
765EXPORT_SYMBOL(schedule_delayed_work); 2559EXPORT_SYMBOL(schedule_delayed_work);
766 2560
@@ -773,9 +2567,8 @@ EXPORT_SYMBOL(schedule_delayed_work);
773void flush_delayed_work(struct delayed_work *dwork) 2567void flush_delayed_work(struct delayed_work *dwork)
774{ 2568{
775 if (del_timer_sync(&dwork->timer)) { 2569 if (del_timer_sync(&dwork->timer)) {
776 struct cpu_workqueue_struct *cwq; 2570 __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq,
777 cwq = wq_per_cpu(get_wq_data(&dwork->work)->wq, get_cpu()); 2571 &dwork->work);
778 __queue_work(cwq, &dwork->work);
779 put_cpu(); 2572 put_cpu();
780 } 2573 }
781 flush_work(&dwork->work); 2574 flush_work(&dwork->work);
@@ -794,7 +2587,7 @@ EXPORT_SYMBOL(flush_delayed_work);
794int schedule_delayed_work_on(int cpu, 2587int schedule_delayed_work_on(int cpu,
795 struct delayed_work *dwork, unsigned long delay) 2588 struct delayed_work *dwork, unsigned long delay)
796{ 2589{
797 return queue_delayed_work_on(cpu, keventd_wq, dwork, delay); 2590 return queue_delayed_work_on(cpu, system_wq, dwork, delay);
798} 2591}
799EXPORT_SYMBOL(schedule_delayed_work_on); 2592EXPORT_SYMBOL(schedule_delayed_work_on);
800 2593
@@ -810,8 +2603,7 @@ EXPORT_SYMBOL(schedule_delayed_work_on);
810int schedule_on_each_cpu(work_func_t func) 2603int schedule_on_each_cpu(work_func_t func)
811{ 2604{
812 int cpu; 2605 int cpu;
813 int orig = -1; 2606 struct work_struct __percpu *works;
814 struct work_struct *works;
815 2607
816 works = alloc_percpu(struct work_struct); 2608 works = alloc_percpu(struct work_struct);
817 if (!works) 2609 if (!works)
@@ -819,23 +2611,12 @@ int schedule_on_each_cpu(work_func_t func)
819 2611
820 get_online_cpus(); 2612 get_online_cpus();
821 2613
822 /*
823 * When running in keventd don't schedule a work item on
824 * itself. Can just call directly because the work queue is
825 * already bound. This also is faster.
826 */
827 if (current_is_keventd())
828 orig = raw_smp_processor_id();
829
830 for_each_online_cpu(cpu) { 2614 for_each_online_cpu(cpu) {
831 struct work_struct *work = per_cpu_ptr(works, cpu); 2615 struct work_struct *work = per_cpu_ptr(works, cpu);
832 2616
833 INIT_WORK(work, func); 2617 INIT_WORK(work, func);
834 if (cpu != orig) 2618 schedule_work_on(cpu, work);
835 schedule_work_on(cpu, work);
836 } 2619 }
837 if (orig >= 0)
838 func(per_cpu_ptr(works, orig));
839 2620
840 for_each_online_cpu(cpu) 2621 for_each_online_cpu(cpu)
841 flush_work(per_cpu_ptr(works, cpu)); 2622 flush_work(per_cpu_ptr(works, cpu));
@@ -845,9 +2626,33 @@ int schedule_on_each_cpu(work_func_t func)
845 return 0; 2626 return 0;
846} 2627}
847 2628
2629/**
2630 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2631 *
2632 * Forces execution of the kernel-global workqueue and blocks until its
2633 * completion.
2634 *
2635 * Think twice before calling this function! It's very easy to get into
2636 * trouble if you don't take great care. Either of the following situations
2637 * will lead to deadlock:
2638 *
2639 * One of the work items currently on the workqueue needs to acquire
2640 * a lock held by your code or its caller.
2641 *
2642 * Your code is running in the context of a work routine.
2643 *
2644 * They will be detected by lockdep when they occur, but the first might not
2645 * occur very often. It depends on what work items are on the workqueue and
2646 * what locks they need, which you have no control over.
2647 *
2648 * In most situations flushing the entire workqueue is overkill; you merely
2649 * need to know that a particular work item isn't queued and isn't running.
2650 * In such cases you should use cancel_delayed_work_sync() or
2651 * cancel_work_sync() instead.
2652 */
848void flush_scheduled_work(void) 2653void flush_scheduled_work(void)
849{ 2654{
850 flush_workqueue(keventd_wq); 2655 flush_workqueue(system_wq);
851} 2656}
852EXPORT_SYMBOL(flush_scheduled_work); 2657EXPORT_SYMBOL(flush_scheduled_work);
853 2658
@@ -879,170 +2684,169 @@ EXPORT_SYMBOL_GPL(execute_in_process_context);
879 2684
880int keventd_up(void) 2685int keventd_up(void)
881{ 2686{
882 return keventd_wq != NULL; 2687 return system_wq != NULL;
883} 2688}
884 2689
885int current_is_keventd(void) 2690static int alloc_cwqs(struct workqueue_struct *wq)
886{ 2691{
887 struct cpu_workqueue_struct *cwq; 2692 /*
888 int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ 2693 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
889 int ret = 0; 2694 * Make sure that the alignment isn't lower than that of
890 2695 * unsigned long long.
891 BUG_ON(!keventd_wq); 2696 */
2697 const size_t size = sizeof(struct cpu_workqueue_struct);
2698 const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
2699 __alignof__(unsigned long long));
2700#ifdef CONFIG_SMP
2701 bool percpu = !(wq->flags & WQ_UNBOUND);
2702#else
2703 bool percpu = false;
2704#endif
892 2705
893 cwq = per_cpu_ptr(keventd_wq->cpu_wq, cpu); 2706 if (percpu)
894 if (current == cwq->thread) 2707 wq->cpu_wq.pcpu = __alloc_percpu(size, align);
895 ret = 1; 2708 else {
2709 void *ptr;
896 2710
897 return ret; 2711 /*
2712 * Allocate enough room to align cwq and put an extra
2713 * pointer at the end pointing back to the originally
2714 * allocated pointer which will be used for free.
2715 */
2716 ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
2717 if (ptr) {
2718 wq->cpu_wq.single = PTR_ALIGN(ptr, align);
2719 *(void **)(wq->cpu_wq.single + 1) = ptr;
2720 }
2721 }
898 2722
2723 /* just in case, make sure it's actually aligned */
2724 BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
2725 return wq->cpu_wq.v ? 0 : -ENOMEM;
899} 2726}
900 2727
901static struct cpu_workqueue_struct * 2728static void free_cwqs(struct workqueue_struct *wq)
902init_cpu_workqueue(struct workqueue_struct *wq, int cpu)
903{ 2729{
904 struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); 2730#ifdef CONFIG_SMP
905 2731 bool percpu = !(wq->flags & WQ_UNBOUND);
906 cwq->wq = wq; 2732#else
907 spin_lock_init(&cwq->lock); 2733 bool percpu = false;
908 INIT_LIST_HEAD(&cwq->worklist); 2734#endif
909 init_waitqueue_head(&cwq->more_work);
910 2735
911 return cwq; 2736 if (percpu)
2737 free_percpu(wq->cpu_wq.pcpu);
2738 else if (wq->cpu_wq.single) {
2739 /* the pointer to free is stored right after the cwq */
2740 kfree(*(void **)(wq->cpu_wq.single + 1));
2741 }
912} 2742}
913 2743
914static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) 2744static int wq_clamp_max_active(int max_active, unsigned int flags,
2745 const char *name)
915{ 2746{
916 struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; 2747 int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
917 struct workqueue_struct *wq = cwq->wq;
918 const char *fmt = is_wq_single_threaded(wq) ? "%s" : "%s/%d";
919 struct task_struct *p;
920 2748
921 p = kthread_create(worker_thread, cwq, fmt, wq->name, cpu); 2749 if (max_active < 1 || max_active > lim)
922 /* 2750 printk(KERN_WARNING "workqueue: max_active %d requested for %s "
923 * Nobody can add the work_struct to this cwq, 2751 "is out of range, clamping between %d and %d\n",
924 * if (caller is __create_workqueue) 2752 max_active, name, 1, lim);
925 * nobody should see this wq
926 * else // caller is CPU_UP_PREPARE
927 * cpu is not on cpu_online_map
928 * so we can abort safely.
929 */
930 if (IS_ERR(p))
931 return PTR_ERR(p);
932 if (cwq->wq->rt)
933 sched_setscheduler_nocheck(p, SCHED_FIFO, &param);
934 cwq->thread = p;
935 2753
936 trace_workqueue_creation(cwq->thread, cpu); 2754 return clamp_val(max_active, 1, lim);
937
938 return 0;
939} 2755}
940 2756
941static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) 2757struct workqueue_struct *__alloc_workqueue_key(const char *name,
2758 unsigned int flags,
2759 int max_active,
2760 struct lock_class_key *key,
2761 const char *lock_name)
942{ 2762{
943 struct task_struct *p = cwq->thread; 2763 struct workqueue_struct *wq;
2764 unsigned int cpu;
944 2765
945 if (p != NULL) { 2766 /*
946 if (cpu >= 0) 2767 * Unbound workqueues aren't concurrency managed and should be
947 kthread_bind(p, cpu); 2768 * dispatched to workers immediately.
948 wake_up_process(p); 2769 */
949 } 2770 if (flags & WQ_UNBOUND)
950} 2771 flags |= WQ_HIGHPRI;
951 2772
952struct workqueue_struct *__create_workqueue_key(const char *name, 2773 max_active = max_active ?: WQ_DFL_ACTIVE;
953 int singlethread, 2774 max_active = wq_clamp_max_active(max_active, flags, name);
954 int freezeable,
955 int rt,
956 struct lock_class_key *key,
957 const char *lock_name)
958{
959 struct workqueue_struct *wq;
960 struct cpu_workqueue_struct *cwq;
961 int err = 0, cpu;
962 2775
963 wq = kzalloc(sizeof(*wq), GFP_KERNEL); 2776 wq = kzalloc(sizeof(*wq), GFP_KERNEL);
964 if (!wq) 2777 if (!wq)
965 return NULL; 2778 goto err;
966 2779
967 wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct); 2780 wq->flags = flags;
968 if (!wq->cpu_wq) { 2781 wq->saved_max_active = max_active;
969 kfree(wq); 2782 mutex_init(&wq->flush_mutex);
970 return NULL; 2783 atomic_set(&wq->nr_cwqs_to_flush, 0);
971 } 2784 INIT_LIST_HEAD(&wq->flusher_queue);
2785 INIT_LIST_HEAD(&wq->flusher_overflow);
972 2786
973 wq->name = name; 2787 wq->name = name;
974 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 2788 lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
975 wq->singlethread = singlethread;
976 wq->freezeable = freezeable;
977 wq->rt = rt;
978 INIT_LIST_HEAD(&wq->list); 2789 INIT_LIST_HEAD(&wq->list);
979 2790
980 if (singlethread) { 2791 if (alloc_cwqs(wq) < 0)
981 cwq = init_cpu_workqueue(wq, singlethread_cpu); 2792 goto err;
982 err = create_workqueue_thread(cwq, singlethread_cpu); 2793
983 start_workqueue_thread(cwq, -1); 2794 for_each_cwq_cpu(cpu, wq) {
984 } else { 2795 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
985 cpu_maps_update_begin(); 2796 struct global_cwq *gcwq = get_gcwq(cpu);
986 /* 2797
987 * We must place this wq on list even if the code below fails. 2798 BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
988 * cpu_down(cpu) can remove cpu from cpu_populated_map before 2799 cwq->gcwq = gcwq;
989 * destroy_workqueue() takes the lock, in that case we leak 2800 cwq->wq = wq;
990 * cwq[cpu]->thread. 2801 cwq->flush_color = -1;
991 */ 2802 cwq->max_active = max_active;
992 spin_lock(&workqueue_lock); 2803 INIT_LIST_HEAD(&cwq->delayed_works);
993 list_add(&wq->list, &workqueues);
994 spin_unlock(&workqueue_lock);
995 /*
996 * We must initialize cwqs for each possible cpu even if we
997 * are going to call destroy_workqueue() finally. Otherwise
998 * cpu_up() can hit the uninitialized cwq once we drop the
999 * lock.
1000 */
1001 for_each_possible_cpu(cpu) {
1002 cwq = init_cpu_workqueue(wq, cpu);
1003 if (err || !cpu_online(cpu))
1004 continue;
1005 err = create_workqueue_thread(cwq, cpu);
1006 start_workqueue_thread(cwq, cpu);
1007 }
1008 cpu_maps_update_done();
1009 } 2804 }
1010 2805
1011 if (err) { 2806 if (flags & WQ_RESCUER) {
1012 destroy_workqueue(wq); 2807 struct worker *rescuer;
1013 wq = NULL; 2808
2809 if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL))
2810 goto err;
2811
2812 wq->rescuer = rescuer = alloc_worker();
2813 if (!rescuer)
2814 goto err;
2815
2816 rescuer->task = kthread_create(rescuer_thread, wq, "%s", name);
2817 if (IS_ERR(rescuer->task))
2818 goto err;
2819
2820 rescuer->task->flags |= PF_THREAD_BOUND;
2821 wake_up_process(rescuer->task);
1014 } 2822 }
1015 return wq;
1016}
1017EXPORT_SYMBOL_GPL(__create_workqueue_key);
1018 2823
1019static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq)
1020{
1021 /* 2824 /*
1022 * Our caller is either destroy_workqueue() or CPU_POST_DEAD, 2825 * workqueue_lock protects global freeze state and workqueues
1023 * cpu_add_remove_lock protects cwq->thread. 2826 * list. Grab it, set max_active accordingly and add the new
2827 * workqueue to workqueues list.
1024 */ 2828 */
1025 if (cwq->thread == NULL) 2829 spin_lock(&workqueue_lock);
1026 return;
1027 2830
1028 lock_map_acquire(&cwq->wq->lockdep_map); 2831 if (workqueue_freezing && wq->flags & WQ_FREEZEABLE)
1029 lock_map_release(&cwq->wq->lockdep_map); 2832 for_each_cwq_cpu(cpu, wq)
2833 get_cwq(cpu, wq)->max_active = 0;
1030 2834
1031 flush_cpu_workqueue(cwq); 2835 list_add(&wq->list, &workqueues);
1032 /* 2836
1033 * If the caller is CPU_POST_DEAD and cwq->worklist was not empty, 2837 spin_unlock(&workqueue_lock);
1034 * a concurrent flush_workqueue() can insert a barrier after us. 2838
1035 * However, in that case run_workqueue() won't return and check 2839 return wq;
1036 * kthread_should_stop() until it flushes all work_struct's. 2840err:
1037 * When ->worklist becomes empty it is safe to exit because no 2841 if (wq) {
1038 * more work_structs can be queued on this cwq: flush_workqueue 2842 free_cwqs(wq);
1039 * checks list_empty(), and a "normal" queue_work() can't use 2843 free_mayday_mask(wq->mayday_mask);
1040 * a dead CPU. 2844 kfree(wq->rescuer);
1041 */ 2845 kfree(wq);
1042 trace_workqueue_destruction(cwq->thread); 2846 }
1043 kthread_stop(cwq->thread); 2847 return NULL;
1044 cwq->thread = NULL;
1045} 2848}
2849EXPORT_SYMBOL_GPL(__alloc_workqueue_key);
1046 2850
1047/** 2851/**
1048 * destroy_workqueue - safely terminate a workqueue 2852 * destroy_workqueue - safely terminate a workqueue
@@ -1052,71 +2856,520 @@ static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq)
1052 */ 2856 */
1053void destroy_workqueue(struct workqueue_struct *wq) 2857void destroy_workqueue(struct workqueue_struct *wq)
1054{ 2858{
1055 const struct cpumask *cpu_map = wq_cpu_map(wq); 2859 unsigned int cpu;
1056 int cpu;
1057 2860
1058 cpu_maps_update_begin(); 2861 wq->flags |= WQ_DYING;
2862 flush_workqueue(wq);
2863
2864 /*
2865 * wq list is used to freeze wq, remove from list after
2866 * flushing is complete in case freeze races us.
2867 */
1059 spin_lock(&workqueue_lock); 2868 spin_lock(&workqueue_lock);
1060 list_del(&wq->list); 2869 list_del(&wq->list);
1061 spin_unlock(&workqueue_lock); 2870 spin_unlock(&workqueue_lock);
1062 2871
1063 for_each_cpu(cpu, cpu_map) 2872 /* sanity check */
1064 cleanup_workqueue_thread(per_cpu_ptr(wq->cpu_wq, cpu)); 2873 for_each_cwq_cpu(cpu, wq) {
1065 cpu_maps_update_done(); 2874 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2875 int i;
2876
2877 for (i = 0; i < WORK_NR_COLORS; i++)
2878 BUG_ON(cwq->nr_in_flight[i]);
2879 BUG_ON(cwq->nr_active);
2880 BUG_ON(!list_empty(&cwq->delayed_works));
2881 }
2882
2883 if (wq->flags & WQ_RESCUER) {
2884 kthread_stop(wq->rescuer->task);
2885 free_mayday_mask(wq->mayday_mask);
2886 kfree(wq->rescuer);
2887 }
1066 2888
1067 free_percpu(wq->cpu_wq); 2889 free_cwqs(wq);
1068 kfree(wq); 2890 kfree(wq);
1069} 2891}
1070EXPORT_SYMBOL_GPL(destroy_workqueue); 2892EXPORT_SYMBOL_GPL(destroy_workqueue);
1071 2893
2894/**
2895 * workqueue_set_max_active - adjust max_active of a workqueue
2896 * @wq: target workqueue
2897 * @max_active: new max_active value.
2898 *
2899 * Set max_active of @wq to @max_active.
2900 *
2901 * CONTEXT:
2902 * Don't call from IRQ context.
2903 */
2904void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
2905{
2906 unsigned int cpu;
2907
2908 max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
2909
2910 spin_lock(&workqueue_lock);
2911
2912 wq->saved_max_active = max_active;
2913
2914 for_each_cwq_cpu(cpu, wq) {
2915 struct global_cwq *gcwq = get_gcwq(cpu);
2916
2917 spin_lock_irq(&gcwq->lock);
2918
2919 if (!(wq->flags & WQ_FREEZEABLE) ||
2920 !(gcwq->flags & GCWQ_FREEZING))
2921 get_cwq(gcwq->cpu, wq)->max_active = max_active;
2922
2923 spin_unlock_irq(&gcwq->lock);
2924 }
2925
2926 spin_unlock(&workqueue_lock);
2927}
2928EXPORT_SYMBOL_GPL(workqueue_set_max_active);
2929
2930/**
2931 * workqueue_congested - test whether a workqueue is congested
2932 * @cpu: CPU in question
2933 * @wq: target workqueue
2934 *
2935 * Test whether @wq's cpu workqueue for @cpu is congested. There is
2936 * no synchronization around this function and the test result is
2937 * unreliable and only useful as advisory hints or for debugging.
2938 *
2939 * RETURNS:
2940 * %true if congested, %false otherwise.
2941 */
2942bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
2943{
2944 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2945
2946 return !list_empty(&cwq->delayed_works);
2947}
2948EXPORT_SYMBOL_GPL(workqueue_congested);
2949
2950/**
2951 * work_cpu - return the last known associated cpu for @work
2952 * @work: the work of interest
2953 *
2954 * RETURNS:
2955 * CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
2956 */
2957unsigned int work_cpu(struct work_struct *work)
2958{
2959 struct global_cwq *gcwq = get_work_gcwq(work);
2960
2961 return gcwq ? gcwq->cpu : WORK_CPU_NONE;
2962}
2963EXPORT_SYMBOL_GPL(work_cpu);
2964
2965/**
2966 * work_busy - test whether a work is currently pending or running
2967 * @work: the work to be tested
2968 *
2969 * Test whether @work is currently pending or running. There is no
2970 * synchronization around this function and the test result is
2971 * unreliable and only useful as advisory hints or for debugging.
2972 * Especially for reentrant wqs, the pending state might hide the
2973 * running state.
2974 *
2975 * RETURNS:
2976 * OR'd bitmask of WORK_BUSY_* bits.
2977 */
2978unsigned int work_busy(struct work_struct *work)
2979{
2980 struct global_cwq *gcwq = get_work_gcwq(work);
2981 unsigned long flags;
2982 unsigned int ret = 0;
2983
2984 if (!gcwq)
2985 return false;
2986
2987 spin_lock_irqsave(&gcwq->lock, flags);
2988
2989 if (work_pending(work))
2990 ret |= WORK_BUSY_PENDING;
2991 if (find_worker_executing_work(gcwq, work))
2992 ret |= WORK_BUSY_RUNNING;
2993
2994 spin_unlock_irqrestore(&gcwq->lock, flags);
2995
2996 return ret;
2997}
2998EXPORT_SYMBOL_GPL(work_busy);
2999
3000/*
3001 * CPU hotplug.
3002 *
3003 * There are two challenges in supporting CPU hotplug. Firstly, there
3004 * are a lot of assumptions on strong associations among work, cwq and
3005 * gcwq which make migrating pending and scheduled works very
3006 * difficult to implement without impacting hot paths. Secondly,
3007 * gcwqs serve mix of short, long and very long running works making
3008 * blocked draining impractical.
3009 *
3010 * This is solved by allowing a gcwq to be detached from CPU, running
3011 * it with unbound (rogue) workers and allowing it to be reattached
3012 * later if the cpu comes back online. A separate thread is created
3013 * to govern a gcwq in such state and is called the trustee of the
3014 * gcwq.
3015 *
3016 * Trustee states and their descriptions.
3017 *
3018 * START Command state used on startup. On CPU_DOWN_PREPARE, a
3019 * new trustee is started with this state.
3020 *
3021 * IN_CHARGE Once started, trustee will enter this state after
3022 * assuming the manager role and making all existing
3023 * workers rogue. DOWN_PREPARE waits for trustee to
3024 * enter this state. After reaching IN_CHARGE, trustee
3025 * tries to execute the pending worklist until it's empty
3026 * and the state is set to BUTCHER, or the state is set
3027 * to RELEASE.
3028 *
3029 * BUTCHER Command state which is set by the cpu callback after
3030 * the cpu has went down. Once this state is set trustee
3031 * knows that there will be no new works on the worklist
3032 * and once the worklist is empty it can proceed to
3033 * killing idle workers.
3034 *
3035 * RELEASE Command state which is set by the cpu callback if the
3036 * cpu down has been canceled or it has come online
3037 * again. After recognizing this state, trustee stops
3038 * trying to drain or butcher and clears ROGUE, rebinds
3039 * all remaining workers back to the cpu and releases
3040 * manager role.
3041 *
3042 * DONE Trustee will enter this state after BUTCHER or RELEASE
3043 * is complete.
3044 *
3045 * trustee CPU draining
3046 * took over down complete
3047 * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
3048 * | | ^
3049 * | CPU is back online v return workers |
3050 * ----------------> RELEASE --------------
3051 */
3052
3053/**
3054 * trustee_wait_event_timeout - timed event wait for trustee
3055 * @cond: condition to wait for
3056 * @timeout: timeout in jiffies
3057 *
3058 * wait_event_timeout() for trustee to use. Handles locking and
3059 * checks for RELEASE request.
3060 *
3061 * CONTEXT:
3062 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3063 * multiple times. To be used by trustee.
3064 *
3065 * RETURNS:
3066 * Positive indicating left time if @cond is satisfied, 0 if timed
3067 * out, -1 if canceled.
3068 */
3069#define trustee_wait_event_timeout(cond, timeout) ({ \
3070 long __ret = (timeout); \
3071 while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \
3072 __ret) { \
3073 spin_unlock_irq(&gcwq->lock); \
3074 __wait_event_timeout(gcwq->trustee_wait, (cond) || \
3075 (gcwq->trustee_state == TRUSTEE_RELEASE), \
3076 __ret); \
3077 spin_lock_irq(&gcwq->lock); \
3078 } \
3079 gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \
3080})
3081
3082/**
3083 * trustee_wait_event - event wait for trustee
3084 * @cond: condition to wait for
3085 *
3086 * wait_event() for trustee to use. Automatically handles locking and
3087 * checks for CANCEL request.
3088 *
3089 * CONTEXT:
3090 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3091 * multiple times. To be used by trustee.
3092 *
3093 * RETURNS:
3094 * 0 if @cond is satisfied, -1 if canceled.
3095 */
3096#define trustee_wait_event(cond) ({ \
3097 long __ret1; \
3098 __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
3099 __ret1 < 0 ? -1 : 0; \
3100})
3101
3102static int __cpuinit trustee_thread(void *__gcwq)
3103{
3104 struct global_cwq *gcwq = __gcwq;
3105 struct worker *worker;
3106 struct work_struct *work;
3107 struct hlist_node *pos;
3108 long rc;
3109 int i;
3110
3111 BUG_ON(gcwq->cpu != smp_processor_id());
3112
3113 spin_lock_irq(&gcwq->lock);
3114 /*
3115 * Claim the manager position and make all workers rogue.
3116 * Trustee must be bound to the target cpu and can't be
3117 * cancelled.
3118 */
3119 BUG_ON(gcwq->cpu != smp_processor_id());
3120 rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS));
3121 BUG_ON(rc < 0);
3122
3123 gcwq->flags |= GCWQ_MANAGING_WORKERS;
3124
3125 list_for_each_entry(worker, &gcwq->idle_list, entry)
3126 worker->flags |= WORKER_ROGUE;
3127
3128 for_each_busy_worker(worker, i, pos, gcwq)
3129 worker->flags |= WORKER_ROGUE;
3130
3131 /*
3132 * Call schedule() so that we cross rq->lock and thus can
3133 * guarantee sched callbacks see the rogue flag. This is
3134 * necessary as scheduler callbacks may be invoked from other
3135 * cpus.
3136 */
3137 spin_unlock_irq(&gcwq->lock);
3138 schedule();
3139 spin_lock_irq(&gcwq->lock);
3140
3141 /*
3142 * Sched callbacks are disabled now. Zap nr_running. After
3143 * this, nr_running stays zero and need_more_worker() and
3144 * keep_working() are always true as long as the worklist is
3145 * not empty.
3146 */
3147 atomic_set(get_gcwq_nr_running(gcwq->cpu), 0);
3148
3149 spin_unlock_irq(&gcwq->lock);
3150 del_timer_sync(&gcwq->idle_timer);
3151 spin_lock_irq(&gcwq->lock);
3152
3153 /*
3154 * We're now in charge. Notify and proceed to drain. We need
3155 * to keep the gcwq running during the whole CPU down
3156 * procedure as other cpu hotunplug callbacks may need to
3157 * flush currently running tasks.
3158 */
3159 gcwq->trustee_state = TRUSTEE_IN_CHARGE;
3160 wake_up_all(&gcwq->trustee_wait);
3161
3162 /*
3163 * The original cpu is in the process of dying and may go away
3164 * anytime now. When that happens, we and all workers would
3165 * be migrated to other cpus. Try draining any left work. We
3166 * want to get it over with ASAP - spam rescuers, wake up as
3167 * many idlers as necessary and create new ones till the
3168 * worklist is empty. Note that if the gcwq is frozen, there
3169 * may be frozen works in freezeable cwqs. Don't declare
3170 * completion while frozen.
3171 */
3172 while (gcwq->nr_workers != gcwq->nr_idle ||
3173 gcwq->flags & GCWQ_FREEZING ||
3174 gcwq->trustee_state == TRUSTEE_IN_CHARGE) {
3175 int nr_works = 0;
3176
3177 list_for_each_entry(work, &gcwq->worklist, entry) {
3178 send_mayday(work);
3179 nr_works++;
3180 }
3181
3182 list_for_each_entry(worker, &gcwq->idle_list, entry) {
3183 if (!nr_works--)
3184 break;
3185 wake_up_process(worker->task);
3186 }
3187
3188 if (need_to_create_worker(gcwq)) {
3189 spin_unlock_irq(&gcwq->lock);
3190 worker = create_worker(gcwq, false);
3191 spin_lock_irq(&gcwq->lock);
3192 if (worker) {
3193 worker->flags |= WORKER_ROGUE;
3194 start_worker(worker);
3195 }
3196 }
3197
3198 /* give a breather */
3199 if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
3200 break;
3201 }
3202
3203 /*
3204 * Either all works have been scheduled and cpu is down, or
3205 * cpu down has already been canceled. Wait for and butcher
3206 * all workers till we're canceled.
3207 */
3208 do {
3209 rc = trustee_wait_event(!list_empty(&gcwq->idle_list));
3210 while (!list_empty(&gcwq->idle_list))
3211 destroy_worker(list_first_entry(&gcwq->idle_list,
3212 struct worker, entry));
3213 } while (gcwq->nr_workers && rc >= 0);
3214
3215 /*
3216 * At this point, either draining has completed and no worker
3217 * is left, or cpu down has been canceled or the cpu is being
3218 * brought back up. There shouldn't be any idle one left.
3219 * Tell the remaining busy ones to rebind once it finishes the
3220 * currently scheduled works by scheduling the rebind_work.
3221 */
3222 WARN_ON(!list_empty(&gcwq->idle_list));
3223
3224 for_each_busy_worker(worker, i, pos, gcwq) {
3225 struct work_struct *rebind_work = &worker->rebind_work;
3226
3227 /*
3228 * Rebind_work may race with future cpu hotplug
3229 * operations. Use a separate flag to mark that
3230 * rebinding is scheduled.
3231 */
3232 worker->flags |= WORKER_REBIND;
3233 worker->flags &= ~WORKER_ROGUE;
3234
3235 /* queue rebind_work, wq doesn't matter, use the default one */
3236 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
3237 work_data_bits(rebind_work)))
3238 continue;
3239
3240 debug_work_activate(rebind_work);
3241 insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
3242 worker->scheduled.next,
3243 work_color_to_flags(WORK_NO_COLOR));
3244 }
3245
3246 /* relinquish manager role */
3247 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
3248
3249 /* notify completion */
3250 gcwq->trustee = NULL;
3251 gcwq->trustee_state = TRUSTEE_DONE;
3252 wake_up_all(&gcwq->trustee_wait);
3253 spin_unlock_irq(&gcwq->lock);
3254 return 0;
3255}
3256
3257/**
3258 * wait_trustee_state - wait for trustee to enter the specified state
3259 * @gcwq: gcwq the trustee of interest belongs to
3260 * @state: target state to wait for
3261 *
3262 * Wait for the trustee to reach @state. DONE is already matched.
3263 *
3264 * CONTEXT:
3265 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3266 * multiple times. To be used by cpu_callback.
3267 */
3268static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state)
3269__releases(&gcwq->lock)
3270__acquires(&gcwq->lock)
3271{
3272 if (!(gcwq->trustee_state == state ||
3273 gcwq->trustee_state == TRUSTEE_DONE)) {
3274 spin_unlock_irq(&gcwq->lock);
3275 __wait_event(gcwq->trustee_wait,
3276 gcwq->trustee_state == state ||
3277 gcwq->trustee_state == TRUSTEE_DONE);
3278 spin_lock_irq(&gcwq->lock);
3279 }
3280}
3281
1072static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, 3282static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
1073 unsigned long action, 3283 unsigned long action,
1074 void *hcpu) 3284 void *hcpu)
1075{ 3285{
1076 unsigned int cpu = (unsigned long)hcpu; 3286 unsigned int cpu = (unsigned long)hcpu;
1077 struct cpu_workqueue_struct *cwq; 3287 struct global_cwq *gcwq = get_gcwq(cpu);
1078 struct workqueue_struct *wq; 3288 struct task_struct *new_trustee = NULL;
1079 int ret = NOTIFY_OK; 3289 struct worker *uninitialized_var(new_worker);
3290 unsigned long flags;
1080 3291
1081 action &= ~CPU_TASKS_FROZEN; 3292 action &= ~CPU_TASKS_FROZEN;
1082 3293
1083 switch (action) { 3294 switch (action) {
3295 case CPU_DOWN_PREPARE:
3296 new_trustee = kthread_create(trustee_thread, gcwq,
3297 "workqueue_trustee/%d\n", cpu);
3298 if (IS_ERR(new_trustee))
3299 return notifier_from_errno(PTR_ERR(new_trustee));
3300 kthread_bind(new_trustee, cpu);
3301 /* fall through */
1084 case CPU_UP_PREPARE: 3302 case CPU_UP_PREPARE:
1085 cpumask_set_cpu(cpu, cpu_populated_map); 3303 BUG_ON(gcwq->first_idle);
1086 } 3304 new_worker = create_worker(gcwq, false);
1087undo: 3305 if (!new_worker) {
1088 list_for_each_entry(wq, &workqueues, list) { 3306 if (new_trustee)
1089 cwq = per_cpu_ptr(wq->cpu_wq, cpu); 3307 kthread_stop(new_trustee);
1090 3308 return NOTIFY_BAD;
1091 switch (action) {
1092 case CPU_UP_PREPARE:
1093 if (!create_workqueue_thread(cwq, cpu))
1094 break;
1095 printk(KERN_ERR "workqueue [%s] for %i failed\n",
1096 wq->name, cpu);
1097 action = CPU_UP_CANCELED;
1098 ret = NOTIFY_BAD;
1099 goto undo;
1100
1101 case CPU_ONLINE:
1102 start_workqueue_thread(cwq, cpu);
1103 break;
1104
1105 case CPU_UP_CANCELED:
1106 start_workqueue_thread(cwq, -1);
1107 case CPU_POST_DEAD:
1108 cleanup_workqueue_thread(cwq);
1109 break;
1110 } 3309 }
1111 } 3310 }
1112 3311
3312 /* some are called w/ irq disabled, don't disturb irq status */
3313 spin_lock_irqsave(&gcwq->lock, flags);
3314
1113 switch (action) { 3315 switch (action) {
1114 case CPU_UP_CANCELED: 3316 case CPU_DOWN_PREPARE:
3317 /* initialize trustee and tell it to acquire the gcwq */
3318 BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE);
3319 gcwq->trustee = new_trustee;
3320 gcwq->trustee_state = TRUSTEE_START;
3321 wake_up_process(gcwq->trustee);
3322 wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);
3323 /* fall through */
3324 case CPU_UP_PREPARE:
3325 BUG_ON(gcwq->first_idle);
3326 gcwq->first_idle = new_worker;
3327 break;
3328
3329 case CPU_DYING:
3330 /*
3331 * Before this, the trustee and all workers except for
3332 * the ones which are still executing works from
3333 * before the last CPU down must be on the cpu. After
3334 * this, they'll all be diasporas.
3335 */
3336 gcwq->flags |= GCWQ_DISASSOCIATED;
3337 break;
3338
1115 case CPU_POST_DEAD: 3339 case CPU_POST_DEAD:
1116 cpumask_clear_cpu(cpu, cpu_populated_map); 3340 gcwq->trustee_state = TRUSTEE_BUTCHER;
3341 /* fall through */
3342 case CPU_UP_CANCELED:
3343 destroy_worker(gcwq->first_idle);
3344 gcwq->first_idle = NULL;
3345 break;
3346
3347 case CPU_DOWN_FAILED:
3348 case CPU_ONLINE:
3349 gcwq->flags &= ~GCWQ_DISASSOCIATED;
3350 if (gcwq->trustee_state != TRUSTEE_DONE) {
3351 gcwq->trustee_state = TRUSTEE_RELEASE;
3352 wake_up_process(gcwq->trustee);
3353 wait_trustee_state(gcwq, TRUSTEE_DONE);
3354 }
3355
3356 /*
3357 * Trustee is done and there might be no worker left.
3358 * Put the first_idle in and request a real manager to
3359 * take a look.
3360 */
3361 spin_unlock_irq(&gcwq->lock);
3362 kthread_bind(gcwq->first_idle->task, cpu);
3363 spin_lock_irq(&gcwq->lock);
3364 gcwq->flags |= GCWQ_MANAGE_WORKERS;
3365 start_worker(gcwq->first_idle);
3366 gcwq->first_idle = NULL;
3367 break;
1117 } 3368 }
1118 3369
1119 return ret; 3370 spin_unlock_irqrestore(&gcwq->lock, flags);
3371
3372 return notifier_from_errno(0);
1120} 3373}
1121 3374
1122#ifdef CONFIG_SMP 3375#ifdef CONFIG_SMP
@@ -1166,14 +3419,200 @@ long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
1166EXPORT_SYMBOL_GPL(work_on_cpu); 3419EXPORT_SYMBOL_GPL(work_on_cpu);
1167#endif /* CONFIG_SMP */ 3420#endif /* CONFIG_SMP */
1168 3421
1169void __init init_workqueues(void) 3422#ifdef CONFIG_FREEZER
3423
3424/**
3425 * freeze_workqueues_begin - begin freezing workqueues
3426 *
3427 * Start freezing workqueues. After this function returns, all
3428 * freezeable workqueues will queue new works to their frozen_works
3429 * list instead of gcwq->worklist.
3430 *
3431 * CONTEXT:
3432 * Grabs and releases workqueue_lock and gcwq->lock's.
3433 */
3434void freeze_workqueues_begin(void)
3435{
3436 unsigned int cpu;
3437
3438 spin_lock(&workqueue_lock);
3439
3440 BUG_ON(workqueue_freezing);
3441 workqueue_freezing = true;
3442
3443 for_each_gcwq_cpu(cpu) {
3444 struct global_cwq *gcwq = get_gcwq(cpu);
3445 struct workqueue_struct *wq;
3446
3447 spin_lock_irq(&gcwq->lock);
3448
3449 BUG_ON(gcwq->flags & GCWQ_FREEZING);
3450 gcwq->flags |= GCWQ_FREEZING;
3451
3452 list_for_each_entry(wq, &workqueues, list) {
3453 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3454
3455 if (cwq && wq->flags & WQ_FREEZEABLE)
3456 cwq->max_active = 0;
3457 }
3458
3459 spin_unlock_irq(&gcwq->lock);
3460 }
3461
3462 spin_unlock(&workqueue_lock);
3463}
3464
3465/**
3466 * freeze_workqueues_busy - are freezeable workqueues still busy?
3467 *
3468 * Check whether freezing is complete. This function must be called
3469 * between freeze_workqueues_begin() and thaw_workqueues().
3470 *
3471 * CONTEXT:
3472 * Grabs and releases workqueue_lock.
3473 *
3474 * RETURNS:
3475 * %true if some freezeable workqueues are still busy. %false if
3476 * freezing is complete.
3477 */
3478bool freeze_workqueues_busy(void)
3479{
3480 unsigned int cpu;
3481 bool busy = false;
3482
3483 spin_lock(&workqueue_lock);
3484
3485 BUG_ON(!workqueue_freezing);
3486
3487 for_each_gcwq_cpu(cpu) {
3488 struct workqueue_struct *wq;
3489 /*
3490 * nr_active is monotonically decreasing. It's safe
3491 * to peek without lock.
3492 */
3493 list_for_each_entry(wq, &workqueues, list) {
3494 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3495
3496 if (!cwq || !(wq->flags & WQ_FREEZEABLE))
3497 continue;
3498
3499 BUG_ON(cwq->nr_active < 0);
3500 if (cwq->nr_active) {
3501 busy = true;
3502 goto out_unlock;
3503 }
3504 }
3505 }
3506out_unlock:
3507 spin_unlock(&workqueue_lock);
3508 return busy;
3509}
3510
3511/**
3512 * thaw_workqueues - thaw workqueues
3513 *
3514 * Thaw workqueues. Normal queueing is restored and all collected
3515 * frozen works are transferred to their respective gcwq worklists.
3516 *
3517 * CONTEXT:
3518 * Grabs and releases workqueue_lock and gcwq->lock's.
3519 */
3520void thaw_workqueues(void)
3521{
3522 unsigned int cpu;
3523
3524 spin_lock(&workqueue_lock);
3525
3526 if (!workqueue_freezing)
3527 goto out_unlock;
3528
3529 for_each_gcwq_cpu(cpu) {
3530 struct global_cwq *gcwq = get_gcwq(cpu);
3531 struct workqueue_struct *wq;
3532
3533 spin_lock_irq(&gcwq->lock);
3534
3535 BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
3536 gcwq->flags &= ~GCWQ_FREEZING;
3537
3538 list_for_each_entry(wq, &workqueues, list) {
3539 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3540
3541 if (!cwq || !(wq->flags & WQ_FREEZEABLE))
3542 continue;
3543
3544 /* restore max_active and repopulate worklist */
3545 cwq->max_active = wq->saved_max_active;
3546
3547 while (!list_empty(&cwq->delayed_works) &&
3548 cwq->nr_active < cwq->max_active)
3549 cwq_activate_first_delayed(cwq);
3550 }
3551
3552 wake_up_worker(gcwq);
3553
3554 spin_unlock_irq(&gcwq->lock);
3555 }
3556
3557 workqueue_freezing = false;
3558out_unlock:
3559 spin_unlock(&workqueue_lock);
3560}
3561#endif /* CONFIG_FREEZER */
3562
3563static int __init init_workqueues(void)
1170{ 3564{
1171 alloc_cpumask_var(&cpu_populated_map, GFP_KERNEL); 3565 unsigned int cpu;
3566 int i;
3567
3568 cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
3569
3570 /* initialize gcwqs */
3571 for_each_gcwq_cpu(cpu) {
3572 struct global_cwq *gcwq = get_gcwq(cpu);
3573
3574 spin_lock_init(&gcwq->lock);
3575 INIT_LIST_HEAD(&gcwq->worklist);
3576 gcwq->cpu = cpu;
3577 gcwq->flags |= GCWQ_DISASSOCIATED;
3578
3579 INIT_LIST_HEAD(&gcwq->idle_list);
3580 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
3581 INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
3582
3583 init_timer_deferrable(&gcwq->idle_timer);
3584 gcwq->idle_timer.function = idle_worker_timeout;
3585 gcwq->idle_timer.data = (unsigned long)gcwq;
1172 3586
1173 cpumask_copy(cpu_populated_map, cpu_online_mask); 3587 setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout,
1174 singlethread_cpu = cpumask_first(cpu_possible_mask); 3588 (unsigned long)gcwq);
1175 cpu_singlethread_map = cpumask_of(singlethread_cpu); 3589
1176 hotcpu_notifier(workqueue_cpu_callback, 0); 3590 ida_init(&gcwq->worker_ida);
1177 keventd_wq = create_workqueue("events"); 3591
1178 BUG_ON(!keventd_wq); 3592 gcwq->trustee_state = TRUSTEE_DONE;
3593 init_waitqueue_head(&gcwq->trustee_wait);
3594 }
3595
3596 /* create the initial worker */
3597 for_each_online_gcwq_cpu(cpu) {
3598 struct global_cwq *gcwq = get_gcwq(cpu);
3599 struct worker *worker;
3600
3601 if (cpu != WORK_CPU_UNBOUND)
3602 gcwq->flags &= ~GCWQ_DISASSOCIATED;
3603 worker = create_worker(gcwq, true);
3604 BUG_ON(!worker);
3605 spin_lock_irq(&gcwq->lock);
3606 start_worker(worker);
3607 spin_unlock_irq(&gcwq->lock);
3608 }
3609
3610 system_wq = alloc_workqueue("events", 0, 0);
3611 system_long_wq = alloc_workqueue("events_long", 0, 0);
3612 system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0);
3613 system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
3614 WQ_UNBOUND_MAX_ACTIVE);
3615 BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);
3616 return 0;
1179} 3617}
3618early_initcall(init_workqueues);
generated by cgit v1.2.2 (git 2.25.0) at 2025-02-26 02:16:58 -0500