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authorLinus Torvalds <torvalds@linux-foundation.org>2012-07-24 20:46:16 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-07-24 20:46:16 -0400
commita08489c569dc174cff97d2cb165aa81e3f1501cc (patch)
treec583700a11bab82ea864425004dd5bb03bf8a987 /kernel
parent08d9329c29ec98477e8ac2f7a513f2bfa3e9f3c5 (diff)
parent6fec10a1a5866dda3cd6a825a521fc7c2f226ba5 (diff)
Merge branch 'for-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
Pull workqueue changes from Tejun Heo: "There are three major changes. - WQ_HIGHPRI has been reimplemented so that high priority work items are served by worker threads with -20 nice value from dedicated highpri worker pools. - CPU hotplug support has been reimplemented such that idle workers are kept across CPU hotplug events. This makes CPU hotplug cheaper (for PM) and makes the code simpler. - flush_kthread_work() has been reimplemented so that a work item can be freed while executing. This removes an annoying behavior difference between kthread_worker and workqueue." * 'for-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: fix spurious CPU locality WARN from process_one_work() kthread_worker: reimplement flush_kthread_work() to allow freeing the work item being executed kthread_worker: reorganize to prepare for flush_kthread_work() reimplementation workqueue: simplify CPU hotplug code workqueue: remove CPU offline trustee workqueue: don't butcher idle workers on an offline CPU workqueue: reimplement CPU online rebinding to handle idle workers workqueue: drop @bind from create_worker() workqueue: use mutex for global_cwq manager exclusion workqueue: ROGUE workers are UNBOUND workers workqueue: drop CPU_DYING notifier operation workqueue: perform cpu down operations from low priority cpu_notifier() workqueue: reimplement WQ_HIGHPRI using a separate worker_pool workqueue: introduce NR_WORKER_POOLS and for_each_worker_pool() workqueue: separate out worker_pool flags workqueue: use @pool instead of @gcwq or @cpu where applicable workqueue: factor out worker_pool from global_cwq workqueue: don't use WQ_HIGHPRI for unbound workqueues
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kthread.c88
-rw-r--r--kernel/workqueue.c1144
2 files changed, 584 insertions, 648 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 3d3de633702e..b579af57ea10 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -360,16 +360,12 @@ repeat:
360 struct kthread_work, node); 360 struct kthread_work, node);
361 list_del_init(&work->node); 361 list_del_init(&work->node);
362 } 362 }
363 worker->current_work = work;
363 spin_unlock_irq(&worker->lock); 364 spin_unlock_irq(&worker->lock);
364 365
365 if (work) { 366 if (work) {
366 __set_current_state(TASK_RUNNING); 367 __set_current_state(TASK_RUNNING);
367 work->func(work); 368 work->func(work);
368 smp_wmb(); /* wmb worker-b0 paired with flush-b1 */
369 work->done_seq = work->queue_seq;
370 smp_mb(); /* mb worker-b1 paired with flush-b0 */
371 if (atomic_read(&work->flushing))
372 wake_up_all(&work->done);
373 } else if (!freezing(current)) 369 } else if (!freezing(current))
374 schedule(); 370 schedule();
375 371
@@ -378,6 +374,19 @@ repeat:
378} 374}
379EXPORT_SYMBOL_GPL(kthread_worker_fn); 375EXPORT_SYMBOL_GPL(kthread_worker_fn);
380 376
377/* insert @work before @pos in @worker */
378static void insert_kthread_work(struct kthread_worker *worker,
379 struct kthread_work *work,
380 struct list_head *pos)
381{
382 lockdep_assert_held(&worker->lock);
383
384 list_add_tail(&work->node, pos);
385 work->worker = worker;
386 if (likely(worker->task))
387 wake_up_process(worker->task);
388}
389
381/** 390/**
382 * queue_kthread_work - queue a kthread_work 391 * queue_kthread_work - queue a kthread_work
383 * @worker: target kthread_worker 392 * @worker: target kthread_worker
@@ -395,10 +404,7 @@ bool queue_kthread_work(struct kthread_worker *worker,
395 404
396 spin_lock_irqsave(&worker->lock, flags); 405 spin_lock_irqsave(&worker->lock, flags);
397 if (list_empty(&work->node)) { 406 if (list_empty(&work->node)) {
398 list_add_tail(&work->node, &worker->work_list); 407 insert_kthread_work(worker, work, &worker->work_list);
399 work->queue_seq++;
400 if (likely(worker->task))
401 wake_up_process(worker->task);
402 ret = true; 408 ret = true;
403 } 409 }
404 spin_unlock_irqrestore(&worker->lock, flags); 410 spin_unlock_irqrestore(&worker->lock, flags);
@@ -406,6 +412,18 @@ bool queue_kthread_work(struct kthread_worker *worker,
406} 412}
407EXPORT_SYMBOL_GPL(queue_kthread_work); 413EXPORT_SYMBOL_GPL(queue_kthread_work);
408 414
415struct kthread_flush_work {
416 struct kthread_work work;
417 struct completion done;
418};
419
420static void kthread_flush_work_fn(struct kthread_work *work)
421{
422 struct kthread_flush_work *fwork =
423 container_of(work, struct kthread_flush_work, work);
424 complete(&fwork->done);
425}
426
409/** 427/**
410 * flush_kthread_work - flush a kthread_work 428 * flush_kthread_work - flush a kthread_work
411 * @work: work to flush 429 * @work: work to flush
@@ -414,39 +432,37 @@ EXPORT_SYMBOL_GPL(queue_kthread_work);
414 */ 432 */
415void flush_kthread_work(struct kthread_work *work) 433void flush_kthread_work(struct kthread_work *work)
416{ 434{
417 int seq = work->queue_seq; 435 struct kthread_flush_work fwork = {
418 436 KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
419 atomic_inc(&work->flushing); 437 COMPLETION_INITIALIZER_ONSTACK(fwork.done),
438 };
439 struct kthread_worker *worker;
440 bool noop = false;
420 441
421 /* 442retry:
422 * mb flush-b0 paired with worker-b1, to make sure either 443 worker = work->worker;
423 * worker sees the above increment or we see done_seq update. 444 if (!worker)
424 */ 445 return;
425 smp_mb__after_atomic_inc();
426 446
427 /* A - B <= 0 tests whether B is in front of A regardless of overflow */ 447 spin_lock_irq(&worker->lock);
428 wait_event(work->done, seq - work->done_seq <= 0); 448 if (work->worker != worker) {
429 atomic_dec(&work->flushing); 449 spin_unlock_irq(&worker->lock);
450 goto retry;
451 }
430 452
431 /* 453 if (!list_empty(&work->node))
432 * rmb flush-b1 paired with worker-b0, to make sure our caller 454 insert_kthread_work(worker, &fwork.work, work->node.next);
433 * sees every change made by work->func(). 455 else if (worker->current_work == work)
434 */ 456 insert_kthread_work(worker, &fwork.work, worker->work_list.next);
435 smp_mb__after_atomic_dec(); 457 else
436} 458 noop = true;
437EXPORT_SYMBOL_GPL(flush_kthread_work);
438 459
439struct kthread_flush_work { 460 spin_unlock_irq(&worker->lock);
440 struct kthread_work work;
441 struct completion done;
442};
443 461
444static void kthread_flush_work_fn(struct kthread_work *work) 462 if (!noop)
445{ 463 wait_for_completion(&fwork.done);
446 struct kthread_flush_work *fwork =
447 container_of(work, struct kthread_flush_work, work);
448 complete(&fwork->done);
449} 464}
465EXPORT_SYMBOL_GPL(flush_kthread_work);
450 466
451/** 467/**
452 * flush_kthread_worker - flush all current works on a kthread_worker 468 * flush_kthread_worker - flush all current works on a kthread_worker
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 9a3128dc67df..692d97628a10 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -45,32 +45,41 @@
45#include "workqueue_sched.h" 45#include "workqueue_sched.h"
46 46
47enum { 47enum {
48 /* global_cwq flags */ 48 /*
49 GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ 49 * global_cwq flags
50 GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */ 50 *
51 GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 51 * A bound gcwq is either associated or disassociated with its CPU.
52 GCWQ_FREEZING = 1 << 3, /* freeze in progress */ 52 * While associated (!DISASSOCIATED), all workers are bound to the
53 GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */ 53 * CPU and none has %WORKER_UNBOUND set and concurrency management
54 * is in effect.
55 *
56 * While DISASSOCIATED, the cpu may be offline and all workers have
57 * %WORKER_UNBOUND set and concurrency management disabled, and may
58 * be executing on any CPU. The gcwq behaves as an unbound one.
59 *
60 * Note that DISASSOCIATED can be flipped only while holding
61 * managership of all pools on the gcwq to avoid changing binding
62 * state while create_worker() is in progress.
63 */
64 GCWQ_DISASSOCIATED = 1 << 0, /* cpu can't serve workers */
65 GCWQ_FREEZING = 1 << 1, /* freeze in progress */
66
67 /* pool flags */
68 POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */
54 69
55 /* worker flags */ 70 /* worker flags */
56 WORKER_STARTED = 1 << 0, /* started */ 71 WORKER_STARTED = 1 << 0, /* started */
57 WORKER_DIE = 1 << 1, /* die die die */ 72 WORKER_DIE = 1 << 1, /* die die die */
58 WORKER_IDLE = 1 << 2, /* is idle */ 73 WORKER_IDLE = 1 << 2, /* is idle */
59 WORKER_PREP = 1 << 3, /* preparing to run works */ 74 WORKER_PREP = 1 << 3, /* preparing to run works */
60 WORKER_ROGUE = 1 << 4, /* not bound to any cpu */
61 WORKER_REBIND = 1 << 5, /* mom is home, come back */ 75 WORKER_REBIND = 1 << 5, /* mom is home, come back */
62 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 76 WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
63 WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 77 WORKER_UNBOUND = 1 << 7, /* worker is unbound */
64 78
65 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | 79 WORKER_NOT_RUNNING = WORKER_PREP | WORKER_REBIND | WORKER_UNBOUND |
66 WORKER_CPU_INTENSIVE | WORKER_UNBOUND, 80 WORKER_CPU_INTENSIVE,
67 81
68 /* gcwq->trustee_state */ 82 NR_WORKER_POOLS = 2, /* # worker pools per gcwq */
69 TRUSTEE_START = 0, /* start */
70 TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */
71 TRUSTEE_BUTCHER = 2, /* butcher workers */
72 TRUSTEE_RELEASE = 3, /* release workers */
73 TRUSTEE_DONE = 4, /* trustee is done */
74 83
75 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 84 BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
76 BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, 85 BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER,
@@ -84,13 +93,13 @@ enum {
84 (min two ticks) */ 93 (min two ticks) */
85 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 94 MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
86 CREATE_COOLDOWN = HZ, /* time to breath after fail */ 95 CREATE_COOLDOWN = HZ, /* time to breath after fail */
87 TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */
88 96
89 /* 97 /*
90 * Rescue workers are used only on emergencies and shared by 98 * Rescue workers are used only on emergencies and shared by
91 * all cpus. Give -20. 99 * all cpus. Give -20.
92 */ 100 */
93 RESCUER_NICE_LEVEL = -20, 101 RESCUER_NICE_LEVEL = -20,
102 HIGHPRI_NICE_LEVEL = -20,
94}; 103};
95 104
96/* 105/*
@@ -115,6 +124,8 @@ enum {
115 */ 124 */
116 125
117struct global_cwq; 126struct global_cwq;
127struct worker_pool;
128struct idle_rebind;
118 129
119/* 130/*
120 * The poor guys doing the actual heavy lifting. All on-duty workers 131 * The poor guys doing the actual heavy lifting. All on-duty workers
@@ -131,12 +142,31 @@ struct worker {
131 struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ 142 struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
132 struct list_head scheduled; /* L: scheduled works */ 143 struct list_head scheduled; /* L: scheduled works */
133 struct task_struct *task; /* I: worker task */ 144 struct task_struct *task; /* I: worker task */
134 struct global_cwq *gcwq; /* I: the associated gcwq */ 145 struct worker_pool *pool; /* I: the associated pool */
135 /* 64 bytes boundary on 64bit, 32 on 32bit */ 146 /* 64 bytes boundary on 64bit, 32 on 32bit */
136 unsigned long last_active; /* L: last active timestamp */ 147 unsigned long last_active; /* L: last active timestamp */
137 unsigned int flags; /* X: flags */ 148 unsigned int flags; /* X: flags */
138 int id; /* I: worker id */ 149 int id; /* I: worker id */
139 struct work_struct rebind_work; /* L: rebind worker to cpu */ 150
151 /* for rebinding worker to CPU */
152 struct idle_rebind *idle_rebind; /* L: for idle worker */
153 struct work_struct rebind_work; /* L: for busy worker */
154};
155
156struct worker_pool {
157 struct global_cwq *gcwq; /* I: the owning gcwq */
158 unsigned int flags; /* X: flags */
159
160 struct list_head worklist; /* L: list of pending works */
161 int nr_workers; /* L: total number of workers */
162 int nr_idle; /* L: currently idle ones */
163
164 struct list_head idle_list; /* X: list of idle workers */
165 struct timer_list idle_timer; /* L: worker idle timeout */
166 struct timer_list mayday_timer; /* L: SOS timer for workers */
167
168 struct mutex manager_mutex; /* mutex manager should hold */
169 struct ida worker_ida; /* L: for worker IDs */
140}; 170};
141 171
142/* 172/*
@@ -146,27 +176,16 @@ struct worker {
146 */ 176 */
147struct global_cwq { 177struct global_cwq {
148 spinlock_t lock; /* the gcwq lock */ 178 spinlock_t lock; /* the gcwq lock */
149 struct list_head worklist; /* L: list of pending works */
150 unsigned int cpu; /* I: the associated cpu */ 179 unsigned int cpu; /* I: the associated cpu */
151 unsigned int flags; /* L: GCWQ_* flags */ 180 unsigned int flags; /* L: GCWQ_* flags */
152 181
153 int nr_workers; /* L: total number of workers */ 182 /* workers are chained either in busy_hash or pool idle_list */
154 int nr_idle; /* L: currently idle ones */
155
156 /* workers are chained either in the idle_list or busy_hash */
157 struct list_head idle_list; /* X: list of idle workers */
158 struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; 183 struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE];
159 /* L: hash of busy workers */ 184 /* L: hash of busy workers */
160 185
161 struct timer_list idle_timer; /* L: worker idle timeout */ 186 struct worker_pool pools[2]; /* normal and highpri pools */
162 struct timer_list mayday_timer; /* L: SOS timer for dworkers */
163
164 struct ida worker_ida; /* L: for worker IDs */
165 187
166 struct task_struct *trustee; /* L: for gcwq shutdown */ 188 wait_queue_head_t rebind_hold; /* rebind hold wait */
167 unsigned int trustee_state; /* L: trustee state */
168 wait_queue_head_t trustee_wait; /* trustee wait */
169 struct worker *first_idle; /* L: first idle worker */
170} ____cacheline_aligned_in_smp; 189} ____cacheline_aligned_in_smp;
171 190
172/* 191/*
@@ -175,7 +194,7 @@ struct global_cwq {
175 * aligned at two's power of the number of flag bits. 194 * aligned at two's power of the number of flag bits.
176 */ 195 */
177struct cpu_workqueue_struct { 196struct cpu_workqueue_struct {
178 struct global_cwq *gcwq; /* I: the associated gcwq */ 197 struct worker_pool *pool; /* I: the associated pool */
179 struct workqueue_struct *wq; /* I: the owning workqueue */ 198 struct workqueue_struct *wq; /* I: the owning workqueue */
180 int work_color; /* L: current color */ 199 int work_color; /* L: current color */
181 int flush_color; /* L: flushing color */ 200 int flush_color; /* L: flushing color */
@@ -264,6 +283,10 @@ EXPORT_SYMBOL_GPL(system_nrt_freezable_wq);
264#define CREATE_TRACE_POINTS 283#define CREATE_TRACE_POINTS
265#include <trace/events/workqueue.h> 284#include <trace/events/workqueue.h>
266 285
286#define for_each_worker_pool(pool, gcwq) \
287 for ((pool) = &(gcwq)->pools[0]; \
288 (pool) < &(gcwq)->pools[NR_WORKER_POOLS]; (pool)++)
289
267#define for_each_busy_worker(worker, i, pos, gcwq) \ 290#define for_each_busy_worker(worker, i, pos, gcwq) \
268 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ 291 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
269 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) 292 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
@@ -444,7 +467,7 @@ static bool workqueue_freezing; /* W: have wqs started freezing? */
444 * try_to_wake_up(). Put it in a separate cacheline. 467 * try_to_wake_up(). Put it in a separate cacheline.
445 */ 468 */
446static DEFINE_PER_CPU(struct global_cwq, global_cwq); 469static DEFINE_PER_CPU(struct global_cwq, global_cwq);
447static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); 470static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_WORKER_POOLS]);
448 471
449/* 472/*
450 * Global cpu workqueue and nr_running counter for unbound gcwq. The 473 * Global cpu workqueue and nr_running counter for unbound gcwq. The
@@ -452,10 +475,17 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running);
452 * workers have WORKER_UNBOUND set. 475 * workers have WORKER_UNBOUND set.
453 */ 476 */
454static struct global_cwq unbound_global_cwq; 477static struct global_cwq unbound_global_cwq;
455static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ 478static atomic_t unbound_pool_nr_running[NR_WORKER_POOLS] = {
479 [0 ... NR_WORKER_POOLS - 1] = ATOMIC_INIT(0), /* always 0 */
480};
456 481
457static int worker_thread(void *__worker); 482static int worker_thread(void *__worker);
458 483
484static int worker_pool_pri(struct worker_pool *pool)
485{
486 return pool - pool->gcwq->pools;
487}
488
459static struct global_cwq *get_gcwq(unsigned int cpu) 489static struct global_cwq *get_gcwq(unsigned int cpu)
460{ 490{
461 if (cpu != WORK_CPU_UNBOUND) 491 if (cpu != WORK_CPU_UNBOUND)
@@ -464,12 +494,15 @@ static struct global_cwq *get_gcwq(unsigned int cpu)
464 return &unbound_global_cwq; 494 return &unbound_global_cwq;
465} 495}
466 496
467static atomic_t *get_gcwq_nr_running(unsigned int cpu) 497static atomic_t *get_pool_nr_running(struct worker_pool *pool)
468{ 498{
499 int cpu = pool->gcwq->cpu;
500 int idx = worker_pool_pri(pool);
501
469 if (cpu != WORK_CPU_UNBOUND) 502 if (cpu != WORK_CPU_UNBOUND)
470 return &per_cpu(gcwq_nr_running, cpu); 503 return &per_cpu(pool_nr_running, cpu)[idx];
471 else 504 else
472 return &unbound_gcwq_nr_running; 505 return &unbound_pool_nr_running[idx];
473} 506}
474 507
475static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, 508static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
@@ -555,7 +588,7 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work)
555 588
556 if (data & WORK_STRUCT_CWQ) 589 if (data & WORK_STRUCT_CWQ)
557 return ((struct cpu_workqueue_struct *) 590 return ((struct cpu_workqueue_struct *)
558 (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; 591 (data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq;
559 592
560 cpu = data >> WORK_STRUCT_FLAG_BITS; 593 cpu = data >> WORK_STRUCT_FLAG_BITS;
561 if (cpu == WORK_CPU_NONE) 594 if (cpu == WORK_CPU_NONE)
@@ -566,60 +599,62 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work)
566} 599}
567 600
568/* 601/*
569 * Policy functions. These define the policies on how the global 602 * Policy functions. These define the policies on how the global worker
570 * worker pool is managed. Unless noted otherwise, these functions 603 * pools are managed. Unless noted otherwise, these functions assume that
571 * assume that they're being called with gcwq->lock held. 604 * they're being called with gcwq->lock held.
572 */ 605 */
573 606
574static bool __need_more_worker(struct global_cwq *gcwq) 607static bool __need_more_worker(struct worker_pool *pool)
575{ 608{
576 return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || 609 return !atomic_read(get_pool_nr_running(pool));
577 gcwq->flags & GCWQ_HIGHPRI_PENDING;
578} 610}
579 611
580/* 612/*
581 * Need to wake up a worker? Called from anything but currently 613 * Need to wake up a worker? Called from anything but currently
582 * running workers. 614 * running workers.
615 *
616 * Note that, because unbound workers never contribute to nr_running, this
617 * function will always return %true for unbound gcwq as long as the
618 * worklist isn't empty.
583 */ 619 */
584static bool need_more_worker(struct global_cwq *gcwq) 620static bool need_more_worker(struct worker_pool *pool)
585{ 621{
586 return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); 622 return !list_empty(&pool->worklist) && __need_more_worker(pool);
587} 623}
588 624
589/* Can I start working? Called from busy but !running workers. */ 625/* Can I start working? Called from busy but !running workers. */
590static bool may_start_working(struct global_cwq *gcwq) 626static bool may_start_working(struct worker_pool *pool)
591{ 627{
592 return gcwq->nr_idle; 628 return pool->nr_idle;
593} 629}
594 630
595/* Do I need to keep working? Called from currently running workers. */ 631/* Do I need to keep working? Called from currently running workers. */
596static bool keep_working(struct global_cwq *gcwq) 632static bool keep_working(struct worker_pool *pool)
597{ 633{
598 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 634 atomic_t *nr_running = get_pool_nr_running(pool);
599 635
600 return !list_empty(&gcwq->worklist) && 636 return !list_empty(&pool->worklist) && atomic_read(nr_running) <= 1;
601 (atomic_read(nr_running) <= 1 ||
602 gcwq->flags & GCWQ_HIGHPRI_PENDING);
603} 637}
604 638
605/* Do we need a new worker? Called from manager. */ 639/* Do we need a new worker? Called from manager. */
606static bool need_to_create_worker(struct global_cwq *gcwq) 640static bool need_to_create_worker(struct worker_pool *pool)
607{ 641{
608 return need_more_worker(gcwq) && !may_start_working(gcwq); 642 return need_more_worker(pool) && !may_start_working(pool);
609} 643}
610 644
611/* Do I need to be the manager? */ 645/* Do I need to be the manager? */
612static bool need_to_manage_workers(struct global_cwq *gcwq) 646static bool need_to_manage_workers(struct worker_pool *pool)
613{ 647{
614 return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; 648 return need_to_create_worker(pool) ||
649 (pool->flags & POOL_MANAGE_WORKERS);
615} 650}
616 651
617/* Do we have too many workers and should some go away? */ 652/* Do we have too many workers and should some go away? */
618static bool too_many_workers(struct global_cwq *gcwq) 653static bool too_many_workers(struct worker_pool *pool)
619{ 654{
620 bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; 655 bool managing = mutex_is_locked(&pool->manager_mutex);
621 int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ 656 int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
622 int nr_busy = gcwq->nr_workers - nr_idle; 657 int nr_busy = pool->nr_workers - nr_idle;
623 658
624 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 659 return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
625} 660}
@@ -629,26 +664,26 @@ static bool too_many_workers(struct global_cwq *gcwq)
629 */ 664 */
630 665
631/* Return the first worker. Safe with preemption disabled */ 666/* Return the first worker. Safe with preemption disabled */
632static struct worker *first_worker(struct global_cwq *gcwq) 667static struct worker *first_worker(struct worker_pool *pool)
633{ 668{
634 if (unlikely(list_empty(&gcwq->idle_list))) 669 if (unlikely(list_empty(&pool->idle_list)))
635 return NULL; 670 return NULL;
636 671
637 return list_first_entry(&gcwq->idle_list, struct worker, entry); 672 return list_first_entry(&pool->idle_list, struct worker, entry);
638} 673}
639 674
640/** 675/**
641 * wake_up_worker - wake up an idle worker 676 * wake_up_worker - wake up an idle worker
642 * @gcwq: gcwq to wake worker for 677 * @pool: worker pool to wake worker from
643 * 678 *
644 * Wake up the first idle worker of @gcwq. 679 * Wake up the first idle worker of @pool.
645 * 680 *
646 * CONTEXT: 681 * CONTEXT:
647 * spin_lock_irq(gcwq->lock). 682 * spin_lock_irq(gcwq->lock).
648 */ 683 */
649static void wake_up_worker(struct global_cwq *gcwq) 684static void wake_up_worker(struct worker_pool *pool)
650{ 685{
651 struct worker *worker = first_worker(gcwq); 686 struct worker *worker = first_worker(pool);
652 687
653 if (likely(worker)) 688 if (likely(worker))
654 wake_up_process(worker->task); 689 wake_up_process(worker->task);
@@ -670,7 +705,7 @@ void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
670 struct worker *worker = kthread_data(task); 705 struct worker *worker = kthread_data(task);
671 706
672 if (!(worker->flags & WORKER_NOT_RUNNING)) 707 if (!(worker->flags & WORKER_NOT_RUNNING))
673 atomic_inc(get_gcwq_nr_running(cpu)); 708 atomic_inc(get_pool_nr_running(worker->pool));
674} 709}
675 710
676/** 711/**
@@ -692,8 +727,8 @@ struct task_struct *wq_worker_sleeping(struct task_struct *task,
692 unsigned int cpu) 727 unsigned int cpu)
693{ 728{
694 struct worker *worker = kthread_data(task), *to_wakeup = NULL; 729 struct worker *worker = kthread_data(task), *to_wakeup = NULL;
695 struct global_cwq *gcwq = get_gcwq(cpu); 730 struct worker_pool *pool = worker->pool;
696 atomic_t *nr_running = get_gcwq_nr_running(cpu); 731 atomic_t *nr_running = get_pool_nr_running(pool);
697 732
698 if (worker->flags & WORKER_NOT_RUNNING) 733 if (worker->flags & WORKER_NOT_RUNNING)
699 return NULL; 734 return NULL;
@@ -706,14 +741,14 @@ struct task_struct *wq_worker_sleeping(struct task_struct *task,
706 * worklist not empty test sequence is in insert_work(). 741 * worklist not empty test sequence is in insert_work().
707 * Please read comment there. 742 * Please read comment there.
708 * 743 *
709 * NOT_RUNNING is clear. This means that trustee is not in 744 * NOT_RUNNING is clear. This means that we're bound to and
710 * charge and we're running on the local cpu w/ rq lock held 745 * running on the local cpu w/ rq lock held and preemption
711 * and preemption disabled, which in turn means that none else 746 * disabled, which in turn means that none else could be
712 * could be manipulating idle_list, so dereferencing idle_list 747 * manipulating idle_list, so dereferencing idle_list without gcwq
713 * without gcwq lock is safe. 748 * lock is safe.
714 */ 749 */
715 if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) 750 if (atomic_dec_and_test(nr_running) && !list_empty(&pool->worklist))
716 to_wakeup = first_worker(gcwq); 751 to_wakeup = first_worker(pool);
717 return to_wakeup ? to_wakeup->task : NULL; 752 return to_wakeup ? to_wakeup->task : NULL;
718} 753}
719 754
@@ -733,7 +768,7 @@ struct task_struct *wq_worker_sleeping(struct task_struct *task,
733static inline void worker_set_flags(struct worker *worker, unsigned int flags, 768static inline void worker_set_flags(struct worker *worker, unsigned int flags,
734 bool wakeup) 769 bool wakeup)
735{ 770{
736 struct global_cwq *gcwq = worker->gcwq; 771 struct worker_pool *pool = worker->pool;
737 772
738 WARN_ON_ONCE(worker->task != current); 773 WARN_ON_ONCE(worker->task != current);
739 774
@@ -744,12 +779,12 @@ static inline void worker_set_flags(struct worker *worker, unsigned int flags,
744 */ 779 */
745 if ((flags & WORKER_NOT_RUNNING) && 780 if ((flags & WORKER_NOT_RUNNING) &&
746 !(worker->flags & WORKER_NOT_RUNNING)) { 781 !(worker->flags & WORKER_NOT_RUNNING)) {
747 atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); 782 atomic_t *nr_running = get_pool_nr_running(pool);
748 783
749 if (wakeup) { 784 if (wakeup) {
750 if (atomic_dec_and_test(nr_running) && 785 if (atomic_dec_and_test(nr_running) &&
751 !list_empty(&gcwq->worklist)) 786 !list_empty(&pool->worklist))
752 wake_up_worker(gcwq); 787 wake_up_worker(pool);
753 } else 788 } else
754 atomic_dec(nr_running); 789 atomic_dec(nr_running);
755 } 790 }
@@ -769,7 +804,7 @@ static inline void worker_set_flags(struct worker *worker, unsigned int flags,
769 */ 804 */
770static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 805static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
771{ 806{
772 struct global_cwq *gcwq = worker->gcwq; 807 struct worker_pool *pool = worker->pool;
773 unsigned int oflags = worker->flags; 808 unsigned int oflags = worker->flags;
774 809
775 WARN_ON_ONCE(worker->task != current); 810 WARN_ON_ONCE(worker->task != current);
@@ -783,7 +818,7 @@ static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
783 */ 818 */
784 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 819 if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
785 if (!(worker->flags & WORKER_NOT_RUNNING)) 820 if (!(worker->flags & WORKER_NOT_RUNNING))
786 atomic_inc(get_gcwq_nr_running(gcwq->cpu)); 821 atomic_inc(get_pool_nr_running(pool));
787} 822}
788 823
789/** 824/**
@@ -867,43 +902,6 @@ static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
867} 902}
868 903
869/** 904/**
870 * gcwq_determine_ins_pos - find insertion position
871 * @gcwq: gcwq of interest
872 * @cwq: cwq a work is being queued for
873 *
874 * A work for @cwq is about to be queued on @gcwq, determine insertion
875 * position for the work. If @cwq is for HIGHPRI wq, the work is
876 * queued at the head of the queue but in FIFO order with respect to
877 * other HIGHPRI works; otherwise, at the end of the queue. This
878 * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that
879 * there are HIGHPRI works pending.
880 *
881 * CONTEXT:
882 * spin_lock_irq(gcwq->lock).
883 *
884 * RETURNS:
885 * Pointer to inserstion position.
886 */
887static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq,
888 struct cpu_workqueue_struct *cwq)
889{
890 struct work_struct *twork;
891
892 if (likely(!(cwq->wq->flags & WQ_HIGHPRI)))
893 return &gcwq->worklist;
894
895 list_for_each_entry(twork, &gcwq->worklist, entry) {
896 struct cpu_workqueue_struct *tcwq = get_work_cwq(twork);
897
898 if (!(tcwq->wq->flags & WQ_HIGHPRI))
899 break;
900 }
901
902 gcwq->flags |= GCWQ_HIGHPRI_PENDING;
903 return &twork->entry;
904}
905
906/**
907 * insert_work - insert a work into gcwq 905 * insert_work - insert a work into gcwq
908 * @cwq: cwq @work belongs to 906 * @cwq: cwq @work belongs to
909 * @work: work to insert 907 * @work: work to insert
@@ -920,7 +918,7 @@ static void insert_work(struct cpu_workqueue_struct *cwq,
920 struct work_struct *work, struct list_head *head, 918 struct work_struct *work, struct list_head *head,
921 unsigned int extra_flags) 919 unsigned int extra_flags)
922{ 920{
923 struct global_cwq *gcwq = cwq->gcwq; 921 struct worker_pool *pool = cwq->pool;
924 922
925 /* we own @work, set data and link */ 923 /* we own @work, set data and link */
926 set_work_cwq(work, cwq, extra_flags); 924 set_work_cwq(work, cwq, extra_flags);
@@ -940,8 +938,8 @@ static void insert_work(struct cpu_workqueue_struct *cwq,
940 */ 938 */
941 smp_mb(); 939 smp_mb();
942 940
943 if (__need_more_worker(gcwq)) 941 if (__need_more_worker(pool))
944 wake_up_worker(gcwq); 942 wake_up_worker(pool);
945} 943}
946 944
947/* 945/*
@@ -1043,7 +1041,7 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
1043 if (likely(cwq->nr_active < cwq->max_active)) { 1041 if (likely(cwq->nr_active < cwq->max_active)) {
1044 trace_workqueue_activate_work(work); 1042 trace_workqueue_activate_work(work);
1045 cwq->nr_active++; 1043 cwq->nr_active++;
1046 worklist = gcwq_determine_ins_pos(gcwq, cwq); 1044 worklist = &cwq->pool->worklist;
1047 } else { 1045 } else {
1048 work_flags |= WORK_STRUCT_DELAYED; 1046 work_flags |= WORK_STRUCT_DELAYED;
1049 worklist = &cwq->delayed_works; 1047 worklist = &cwq->delayed_works;
@@ -1192,7 +1190,8 @@ EXPORT_SYMBOL_GPL(queue_delayed_work_on);
1192 */ 1190 */
1193static void worker_enter_idle(struct worker *worker) 1191static void worker_enter_idle(struct worker *worker)
1194{ 1192{
1195 struct global_cwq *gcwq = worker->gcwq; 1193 struct worker_pool *pool = worker->pool;
1194 struct global_cwq *gcwq = pool->gcwq;
1196 1195
1197 BUG_ON(worker->flags & WORKER_IDLE); 1196 BUG_ON(worker->flags & WORKER_IDLE);
1198 BUG_ON(!list_empty(&worker->entry) && 1197 BUG_ON(!list_empty(&worker->entry) &&
@@ -1200,27 +1199,24 @@ static void worker_enter_idle(struct worker *worker)
1200 1199
1201 /* can't use worker_set_flags(), also called from start_worker() */ 1200 /* can't use worker_set_flags(), also called from start_worker() */
1202 worker->flags |= WORKER_IDLE; 1201 worker->flags |= WORKER_IDLE;
1203 gcwq->nr_idle++; 1202 pool->nr_idle++;
1204 worker->last_active = jiffies; 1203 worker->last_active = jiffies;
1205 1204
1206 /* idle_list is LIFO */ 1205 /* idle_list is LIFO */
1207 list_add(&worker->entry, &gcwq->idle_list); 1206 list_add(&worker->entry, &pool->idle_list);
1208 1207
1209 if (likely(!(worker->flags & WORKER_ROGUE))) { 1208 if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
1210 if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) 1209 mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
1211 mod_timer(&gcwq->idle_timer,
1212 jiffies + IDLE_WORKER_TIMEOUT);
1213 } else
1214 wake_up_all(&gcwq->trustee_wait);
1215 1210
1216 /* 1211 /*
1217 * Sanity check nr_running. Because trustee releases gcwq->lock 1212 * Sanity check nr_running. Because gcwq_unbind_fn() releases
1218 * between setting %WORKER_ROGUE and zapping nr_running, the 1213 * gcwq->lock between setting %WORKER_UNBOUND and zapping
1219 * warning may trigger spuriously. Check iff trustee is idle. 1214 * nr_running, the warning may trigger spuriously. Check iff
1215 * unbind is not in progress.
1220 */ 1216 */
1221 WARN_ON_ONCE(gcwq->trustee_state == TRUSTEE_DONE && 1217 WARN_ON_ONCE(!(gcwq->flags & GCWQ_DISASSOCIATED) &&
1222 gcwq->nr_workers == gcwq->nr_idle && 1218 pool->nr_workers == pool->nr_idle &&
1223 atomic_read(get_gcwq_nr_running(gcwq->cpu))); 1219 atomic_read(get_pool_nr_running(pool)));
1224} 1220}
1225 1221
1226/** 1222/**
@@ -1234,11 +1230,11 @@ static void worker_enter_idle(struct worker *worker)
1234 */ 1230 */
1235static void worker_leave_idle(struct worker *worker) 1231static void worker_leave_idle(struct worker *worker)
1236{ 1232{
1237 struct global_cwq *gcwq = worker->gcwq; 1233 struct worker_pool *pool = worker->pool;
1238 1234
1239 BUG_ON(!(worker->flags & WORKER_IDLE)); 1235 BUG_ON(!(worker->flags & WORKER_IDLE));
1240 worker_clr_flags(worker, WORKER_IDLE); 1236 worker_clr_flags(worker, WORKER_IDLE);
1241 gcwq->nr_idle--; 1237 pool->nr_idle--;
1242 list_del_init(&worker->entry); 1238 list_del_init(&worker->entry);
1243} 1239}
1244 1240
@@ -1258,11 +1254,11 @@ static void worker_leave_idle(struct worker *worker)
1258 * verbatim as it's best effort and blocking and gcwq may be 1254 * verbatim as it's best effort and blocking and gcwq may be
1259 * [dis]associated in the meantime. 1255 * [dis]associated in the meantime.
1260 * 1256 *
1261 * This function tries set_cpus_allowed() and locks gcwq and verifies 1257 * This function tries set_cpus_allowed() and locks gcwq and verifies the
1262 * the binding against GCWQ_DISASSOCIATED which is set during 1258 * binding against %GCWQ_DISASSOCIATED which is set during
1263 * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters 1259 * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
1264 * idle state or fetches works without dropping lock, it can guarantee 1260 * enters idle state or fetches works without dropping lock, it can
1265 * the scheduling requirement described in the first paragraph. 1261 * guarantee the scheduling requirement described in the first paragraph.
1266 * 1262 *
1267 * CONTEXT: 1263 * CONTEXT:
1268 * Might sleep. Called without any lock but returns with gcwq->lock 1264 * Might sleep. Called without any lock but returns with gcwq->lock
@@ -1275,7 +1271,7 @@ static void worker_leave_idle(struct worker *worker)
1275static bool worker_maybe_bind_and_lock(struct worker *worker) 1271static bool worker_maybe_bind_and_lock(struct worker *worker)
1276__acquires(&gcwq->lock) 1272__acquires(&gcwq->lock)
1277{ 1273{
1278 struct global_cwq *gcwq = worker->gcwq; 1274 struct global_cwq *gcwq = worker->pool->gcwq;
1279 struct task_struct *task = worker->task; 1275 struct task_struct *task = worker->task;
1280 1276
1281 while (true) { 1277 while (true) {
@@ -1308,16 +1304,40 @@ __acquires(&gcwq->lock)
1308 } 1304 }
1309} 1305}
1310 1306
1307struct idle_rebind {
1308 int cnt; /* # workers to be rebound */
1309 struct completion done; /* all workers rebound */
1310};
1311
1312/*
1313 * Rebind an idle @worker to its CPU. During CPU onlining, this has to
1314 * happen synchronously for idle workers. worker_thread() will test
1315 * %WORKER_REBIND before leaving idle and call this function.
1316 */
1317static void idle_worker_rebind(struct worker *worker)
1318{
1319 struct global_cwq *gcwq = worker->pool->gcwq;
1320
1321 /* CPU must be online at this point */
1322 WARN_ON(!worker_maybe_bind_and_lock(worker));
1323 if (!--worker->idle_rebind->cnt)
1324 complete(&worker->idle_rebind->done);
1325 spin_unlock_irq(&worker->pool->gcwq->lock);
1326
1327 /* we did our part, wait for rebind_workers() to finish up */
1328 wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND));
1329}
1330
1311/* 1331/*
1312 * Function for worker->rebind_work used to rebind rogue busy workers 1332 * Function for @worker->rebind.work used to rebind unbound busy workers to
1313 * to the associated cpu which is coming back online. This is 1333 * the associated cpu which is coming back online. This is scheduled by
1314 * scheduled by cpu up but can race with other cpu hotplug operations 1334 * cpu up but can race with other cpu hotplug operations and may be
1315 * and may be executed twice without intervening cpu down. 1335 * executed twice without intervening cpu down.
1316 */ 1336 */
1317static void worker_rebind_fn(struct work_struct *work) 1337static void busy_worker_rebind_fn(struct work_struct *work)
1318{ 1338{
1319 struct worker *worker = container_of(work, struct worker, rebind_work); 1339 struct worker *worker = container_of(work, struct worker, rebind_work);
1320 struct global_cwq *gcwq = worker->gcwq; 1340 struct global_cwq *gcwq = worker->pool->gcwq;
1321 1341
1322 if (worker_maybe_bind_and_lock(worker)) 1342 if (worker_maybe_bind_and_lock(worker))
1323 worker_clr_flags(worker, WORKER_REBIND); 1343 worker_clr_flags(worker, WORKER_REBIND);
@@ -1325,6 +1345,112 @@ static void worker_rebind_fn(struct work_struct *work)
1325 spin_unlock_irq(&gcwq->lock); 1345 spin_unlock_irq(&gcwq->lock);
1326} 1346}
1327 1347
1348/**
1349 * rebind_workers - rebind all workers of a gcwq to the associated CPU
1350 * @gcwq: gcwq of interest
1351 *
1352 * @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding
1353 * is different for idle and busy ones.
1354 *
1355 * The idle ones should be rebound synchronously and idle rebinding should
1356 * be complete before any worker starts executing work items with
1357 * concurrency management enabled; otherwise, scheduler may oops trying to
1358 * wake up non-local idle worker from wq_worker_sleeping().
1359 *
1360 * This is achieved by repeatedly requesting rebinding until all idle
1361 * workers are known to have been rebound under @gcwq->lock and holding all
1362 * idle workers from becoming busy until idle rebinding is complete.
1363 *
1364 * Once idle workers are rebound, busy workers can be rebound as they
1365 * finish executing their current work items. Queueing the rebind work at
1366 * the head of their scheduled lists is enough. Note that nr_running will
1367 * be properbly bumped as busy workers rebind.
1368 *
1369 * On return, all workers are guaranteed to either be bound or have rebind
1370 * work item scheduled.
1371 */
1372static void rebind_workers(struct global_cwq *gcwq)
1373 __releases(&gcwq->lock) __acquires(&gcwq->lock)
1374{
1375 struct idle_rebind idle_rebind;
1376 struct worker_pool *pool;
1377 struct worker *worker;
1378 struct hlist_node *pos;
1379 int i;
1380
1381 lockdep_assert_held(&gcwq->lock);
1382
1383 for_each_worker_pool(pool, gcwq)
1384 lockdep_assert_held(&pool->manager_mutex);
1385
1386 /*
1387 * Rebind idle workers. Interlocked both ways. We wait for
1388 * workers to rebind via @idle_rebind.done. Workers will wait for
1389 * us to finish up by watching %WORKER_REBIND.
1390 */
1391 init_completion(&idle_rebind.done);
1392retry:
1393 idle_rebind.cnt = 1;
1394 INIT_COMPLETION(idle_rebind.done);
1395
1396 /* set REBIND and kick idle ones, we'll wait for these later */
1397 for_each_worker_pool(pool, gcwq) {
1398 list_for_each_entry(worker, &pool->idle_list, entry) {
1399 if (worker->flags & WORKER_REBIND)
1400 continue;
1401
1402 /* morph UNBOUND to REBIND */
1403 worker->flags &= ~WORKER_UNBOUND;
1404 worker->flags |= WORKER_REBIND;
1405
1406 idle_rebind.cnt++;
1407 worker->idle_rebind = &idle_rebind;
1408
1409 /* worker_thread() will call idle_worker_rebind() */
1410 wake_up_process(worker->task);
1411 }
1412 }
1413
1414 if (--idle_rebind.cnt) {
1415 spin_unlock_irq(&gcwq->lock);
1416 wait_for_completion(&idle_rebind.done);
1417 spin_lock_irq(&gcwq->lock);
1418 /* busy ones might have become idle while waiting, retry */
1419 goto retry;
1420 }
1421
1422 /*
1423 * All idle workers are rebound and waiting for %WORKER_REBIND to
1424 * be cleared inside idle_worker_rebind(). Clear and release.
1425 * Clearing %WORKER_REBIND from this foreign context is safe
1426 * because these workers are still guaranteed to be idle.
1427 */
1428 for_each_worker_pool(pool, gcwq)
1429 list_for_each_entry(worker, &pool->idle_list, entry)
1430 worker->flags &= ~WORKER_REBIND;
1431
1432 wake_up_all(&gcwq->rebind_hold);
1433
1434 /* rebind busy workers */
1435 for_each_busy_worker(worker, i, pos, gcwq) {
1436 struct work_struct *rebind_work = &worker->rebind_work;
1437
1438 /* morph UNBOUND to REBIND */
1439 worker->flags &= ~WORKER_UNBOUND;
1440 worker->flags |= WORKER_REBIND;
1441
1442 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
1443 work_data_bits(rebind_work)))
1444 continue;
1445
1446 /* wq doesn't matter, use the default one */
1447 debug_work_activate(rebind_work);
1448 insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
1449 worker->scheduled.next,
1450 work_color_to_flags(WORK_NO_COLOR));
1451 }
1452}
1453
1328static struct worker *alloc_worker(void) 1454static struct worker *alloc_worker(void)
1329{ 1455{
1330 struct worker *worker; 1456 struct worker *worker;
@@ -1333,7 +1459,7 @@ static struct worker *alloc_worker(void)
1333 if (worker) { 1459 if (worker) {
1334 INIT_LIST_HEAD(&worker->entry); 1460 INIT_LIST_HEAD(&worker->entry);
1335 INIT_LIST_HEAD(&worker->scheduled); 1461 INIT_LIST_HEAD(&worker->scheduled);
1336 INIT_WORK(&worker->rebind_work, worker_rebind_fn); 1462 INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn);
1337 /* on creation a worker is in !idle && prep state */ 1463 /* on creation a worker is in !idle && prep state */
1338 worker->flags = WORKER_PREP; 1464 worker->flags = WORKER_PREP;
1339 } 1465 }
@@ -1342,10 +1468,9 @@ static struct worker *alloc_worker(void)
1342 1468
1343/** 1469/**
1344 * create_worker - create a new workqueue worker 1470 * create_worker - create a new workqueue worker
1345 * @gcwq: gcwq the new worker will belong to 1471 * @pool: pool the new worker will belong to
1346 * @bind: whether to set affinity to @cpu or not
1347 * 1472 *
1348 * Create a new worker which is bound to @gcwq. The returned worker 1473 * Create a new worker which is bound to @pool. The returned worker
1349 * can be started by calling start_worker() or destroyed using 1474 * can be started by calling start_worker() or destroyed using
1350 * destroy_worker(). 1475 * destroy_worker().
1351 * 1476 *
@@ -1355,16 +1480,17 @@ static struct worker *alloc_worker(void)
1355 * RETURNS: 1480 * RETURNS:
1356 * Pointer to the newly created worker. 1481 * Pointer to the newly created worker.
1357 */ 1482 */
1358static struct worker *create_worker(struct global_cwq *gcwq, bool bind) 1483static struct worker *create_worker(struct worker_pool *pool)
1359{ 1484{
1360 bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; 1485 struct global_cwq *gcwq = pool->gcwq;
1486 const char *pri = worker_pool_pri(pool) ? "H" : "";
1361 struct worker *worker = NULL; 1487 struct worker *worker = NULL;
1362 int id = -1; 1488 int id = -1;
1363 1489
1364 spin_lock_irq(&gcwq->lock); 1490 spin_lock_irq(&gcwq->lock);
1365 while (ida_get_new(&gcwq->worker_ida, &id)) { 1491 while (ida_get_new(&pool->worker_ida, &id)) {
1366 spin_unlock_irq(&gcwq->lock); 1492 spin_unlock_irq(&gcwq->lock);
1367 if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) 1493 if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL))
1368 goto fail; 1494 goto fail;
1369 spin_lock_irq(&gcwq->lock); 1495 spin_lock_irq(&gcwq->lock);
1370 } 1496 }
@@ -1374,38 +1500,43 @@ static struct worker *create_worker(struct global_cwq *gcwq, bool bind)
1374 if (!worker) 1500 if (!worker)
1375 goto fail; 1501 goto fail;
1376 1502
1377 worker->gcwq = gcwq; 1503 worker->pool = pool;
1378 worker->id = id; 1504 worker->id = id;
1379 1505
1380 if (!on_unbound_cpu) 1506 if (gcwq->cpu != WORK_CPU_UNBOUND)
1381 worker->task = kthread_create_on_node(worker_thread, 1507 worker->task = kthread_create_on_node(worker_thread,
1382 worker, 1508 worker, cpu_to_node(gcwq->cpu),
1383 cpu_to_node(gcwq->cpu), 1509 "kworker/%u:%d%s", gcwq->cpu, id, pri);
1384 "kworker/%u:%d", gcwq->cpu, id);
1385 else 1510 else
1386 worker->task = kthread_create(worker_thread, worker, 1511 worker->task = kthread_create(worker_thread, worker,
1387 "kworker/u:%d", id); 1512 "kworker/u:%d%s", id, pri);
1388 if (IS_ERR(worker->task)) 1513 if (IS_ERR(worker->task))
1389 goto fail; 1514 goto fail;
1390 1515
1516 if (worker_pool_pri(pool))
1517 set_user_nice(worker->task, HIGHPRI_NICE_LEVEL);
1518
1391 /* 1519 /*
1392 * A rogue worker will become a regular one if CPU comes 1520 * Determine CPU binding of the new worker depending on
1393 * online later on. Make sure every worker has 1521 * %GCWQ_DISASSOCIATED. The caller is responsible for ensuring the
1394 * PF_THREAD_BOUND set. 1522 * flag remains stable across this function. See the comments
1523 * above the flag definition for details.
1524 *
1525 * As an unbound worker may later become a regular one if CPU comes
1526 * online, make sure every worker has %PF_THREAD_BOUND set.
1395 */ 1527 */
1396 if (bind && !on_unbound_cpu) 1528 if (!(gcwq->flags & GCWQ_DISASSOCIATED)) {
1397 kthread_bind(worker->task, gcwq->cpu); 1529 kthread_bind(worker->task, gcwq->cpu);
1398 else { 1530 } else {
1399 worker->task->flags |= PF_THREAD_BOUND; 1531 worker->task->flags |= PF_THREAD_BOUND;
1400 if (on_unbound_cpu) 1532 worker->flags |= WORKER_UNBOUND;
1401 worker->flags |= WORKER_UNBOUND;
1402 } 1533 }
1403 1534
1404 return worker; 1535 return worker;
1405fail: 1536fail:
1406 if (id >= 0) { 1537 if (id >= 0) {
1407 spin_lock_irq(&gcwq->lock); 1538 spin_lock_irq(&gcwq->lock);
1408 ida_remove(&gcwq->worker_ida, id); 1539 ida_remove(&pool->worker_ida, id);
1409 spin_unlock_irq(&gcwq->lock); 1540 spin_unlock_irq(&gcwq->lock);
1410 } 1541 }
1411 kfree(worker); 1542 kfree(worker);
@@ -1424,7 +1555,7 @@ fail:
1424static void start_worker(struct worker *worker) 1555static void start_worker(struct worker *worker)
1425{ 1556{
1426 worker->flags |= WORKER_STARTED; 1557 worker->flags |= WORKER_STARTED;
1427 worker->gcwq->nr_workers++; 1558 worker->pool->nr_workers++;
1428 worker_enter_idle(worker); 1559 worker_enter_idle(worker);
1429 wake_up_process(worker->task); 1560 wake_up_process(worker->task);
1430} 1561}
@@ -1440,7 +1571,8 @@ static void start_worker(struct worker *worker)
1440 */ 1571 */
1441static void destroy_worker(struct worker *worker) 1572static void destroy_worker(struct worker *worker)
1442{ 1573{
1443 struct global_cwq *gcwq = worker->gcwq; 1574 struct worker_pool *pool = worker->pool;
1575 struct global_cwq *gcwq = pool->gcwq;
1444 int id = worker->id; 1576 int id = worker->id;
1445 1577
1446 /* sanity check frenzy */ 1578 /* sanity check frenzy */
@@ -1448,9 +1580,9 @@ static void destroy_worker(struct worker *worker)
1448 BUG_ON(!list_empty(&worker->scheduled)); 1580 BUG_ON(!list_empty(&worker->scheduled));
1449 1581
1450 if (worker->flags & WORKER_STARTED) 1582 if (worker->flags & WORKER_STARTED)
1451 gcwq->nr_workers--; 1583 pool->nr_workers--;
1452 if (worker->flags & WORKER_IDLE) 1584 if (worker->flags & WORKER_IDLE)
1453 gcwq->nr_idle--; 1585 pool->nr_idle--;
1454 1586
1455 list_del_init(&worker->entry); 1587 list_del_init(&worker->entry);
1456 worker->flags |= WORKER_DIE; 1588 worker->flags |= WORKER_DIE;
@@ -1461,29 +1593,30 @@ static void destroy_worker(struct worker *worker)
1461 kfree(worker); 1593 kfree(worker);
1462 1594
1463 spin_lock_irq(&gcwq->lock); 1595 spin_lock_irq(&gcwq->lock);
1464 ida_remove(&gcwq->worker_ida, id); 1596 ida_remove(&pool->worker_ida, id);
1465} 1597}
1466 1598
1467static void idle_worker_timeout(unsigned long __gcwq) 1599static void idle_worker_timeout(unsigned long __pool)
1468{ 1600{
1469 struct global_cwq *gcwq = (void *)__gcwq; 1601 struct worker_pool *pool = (void *)__pool;
1602 struct global_cwq *gcwq = pool->gcwq;
1470 1603
1471 spin_lock_irq(&gcwq->lock); 1604 spin_lock_irq(&gcwq->lock);
1472 1605
1473 if (too_many_workers(gcwq)) { 1606 if (too_many_workers(pool)) {
1474 struct worker *worker; 1607 struct worker *worker;
1475 unsigned long expires; 1608 unsigned long expires;
1476 1609
1477 /* idle_list is kept in LIFO order, check the last one */ 1610 /* idle_list is kept in LIFO order, check the last one */
1478 worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1611 worker = list_entry(pool->idle_list.prev, struct worker, entry);
1479 expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1612 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1480 1613
1481 if (time_before(jiffies, expires)) 1614 if (time_before(jiffies, expires))
1482 mod_timer(&gcwq->idle_timer, expires); 1615 mod_timer(&pool->idle_timer, expires);
1483 else { 1616 else {
1484 /* it's been idle for too long, wake up manager */ 1617 /* it's been idle for too long, wake up manager */
1485 gcwq->flags |= GCWQ_MANAGE_WORKERS; 1618 pool->flags |= POOL_MANAGE_WORKERS;
1486 wake_up_worker(gcwq); 1619 wake_up_worker(pool);
1487 } 1620 }
1488 } 1621 }
1489 1622
@@ -1500,7 +1633,7 @@ static bool send_mayday(struct work_struct *work)
1500 return false; 1633 return false;
1501 1634
1502 /* mayday mayday mayday */ 1635 /* mayday mayday mayday */
1503 cpu = cwq->gcwq->cpu; 1636 cpu = cwq->pool->gcwq->cpu;
1504 /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ 1637 /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
1505 if (cpu == WORK_CPU_UNBOUND) 1638 if (cpu == WORK_CPU_UNBOUND)
1506 cpu = 0; 1639 cpu = 0;
@@ -1509,37 +1642,38 @@ static bool send_mayday(struct work_struct *work)
1509 return true; 1642 return true;
1510} 1643}
1511 1644
1512static void gcwq_mayday_timeout(unsigned long __gcwq) 1645static void gcwq_mayday_timeout(unsigned long __pool)
1513{ 1646{
1514 struct global_cwq *gcwq = (void *)__gcwq; 1647 struct worker_pool *pool = (void *)__pool;
1648 struct global_cwq *gcwq = pool->gcwq;
1515 struct work_struct *work; 1649 struct work_struct *work;
1516 1650
1517 spin_lock_irq(&gcwq->lock); 1651 spin_lock_irq(&gcwq->lock);
1518 1652
1519 if (need_to_create_worker(gcwq)) { 1653 if (need_to_create_worker(pool)) {
1520 /* 1654 /*
1521 * We've been trying to create a new worker but 1655 * We've been trying to create a new worker but
1522 * haven't been successful. We might be hitting an 1656 * haven't been successful. We might be hitting an
1523 * allocation deadlock. Send distress signals to 1657 * allocation deadlock. Send distress signals to
1524 * rescuers. 1658 * rescuers.
1525 */ 1659 */
1526 list_for_each_entry(work, &gcwq->worklist, entry) 1660 list_for_each_entry(work, &pool->worklist, entry)
1527 send_mayday(work); 1661 send_mayday(work);
1528 } 1662 }
1529 1663
1530 spin_unlock_irq(&gcwq->lock); 1664 spin_unlock_irq(&gcwq->lock);
1531 1665
1532 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); 1666 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
1533} 1667}
1534 1668
1535/** 1669/**
1536 * maybe_create_worker - create a new worker if necessary 1670 * maybe_create_worker - create a new worker if necessary
1537 * @gcwq: gcwq to create a new worker for 1671 * @pool: pool to create a new worker for
1538 * 1672 *
1539 * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to 1673 * Create a new worker for @pool if necessary. @pool is guaranteed to
1540 * have at least one idle worker on return from this function. If 1674 * have at least one idle worker on return from this function. If
1541 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 1675 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1542 * sent to all rescuers with works scheduled on @gcwq to resolve 1676 * sent to all rescuers with works scheduled on @pool to resolve
1543 * possible allocation deadlock. 1677 * possible allocation deadlock.
1544 * 1678 *
1545 * On return, need_to_create_worker() is guaranteed to be false and 1679 * On return, need_to_create_worker() is guaranteed to be false and
@@ -1554,52 +1688,54 @@ static void gcwq_mayday_timeout(unsigned long __gcwq)
1554 * false if no action was taken and gcwq->lock stayed locked, true 1688 * false if no action was taken and gcwq->lock stayed locked, true
1555 * otherwise. 1689 * otherwise.
1556 */ 1690 */
1557static bool maybe_create_worker(struct global_cwq *gcwq) 1691static bool maybe_create_worker(struct worker_pool *pool)
1558__releases(&gcwq->lock) 1692__releases(&gcwq->lock)
1559__acquires(&gcwq->lock) 1693__acquires(&gcwq->lock)
1560{ 1694{
1561 if (!need_to_create_worker(gcwq)) 1695 struct global_cwq *gcwq = pool->gcwq;
1696
1697 if (!need_to_create_worker(pool))
1562 return false; 1698 return false;
1563restart: 1699restart:
1564 spin_unlock_irq(&gcwq->lock); 1700 spin_unlock_irq(&gcwq->lock);
1565 1701
1566 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 1702 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1567 mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1703 mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
1568 1704
1569 while (true) { 1705 while (true) {
1570 struct worker *worker; 1706 struct worker *worker;
1571 1707
1572 worker = create_worker(gcwq, true); 1708 worker = create_worker(pool);
1573 if (worker) { 1709 if (worker) {
1574 del_timer_sync(&gcwq->mayday_timer); 1710 del_timer_sync(&pool->mayday_timer);
1575 spin_lock_irq(&gcwq->lock); 1711 spin_lock_irq(&gcwq->lock);
1576 start_worker(worker); 1712 start_worker(worker);
1577 BUG_ON(need_to_create_worker(gcwq)); 1713 BUG_ON(need_to_create_worker(pool));
1578 return true; 1714 return true;
1579 } 1715 }
1580 1716
1581 if (!need_to_create_worker(gcwq)) 1717 if (!need_to_create_worker(pool))
1582 break; 1718 break;
1583 1719
1584 __set_current_state(TASK_INTERRUPTIBLE); 1720 __set_current_state(TASK_INTERRUPTIBLE);
1585 schedule_timeout(CREATE_COOLDOWN); 1721 schedule_timeout(CREATE_COOLDOWN);
1586 1722
1587 if (!need_to_create_worker(gcwq)) 1723 if (!need_to_create_worker(pool))
1588 break; 1724 break;
1589 } 1725 }
1590 1726
1591 del_timer_sync(&gcwq->mayday_timer); 1727 del_timer_sync(&pool->mayday_timer);
1592 spin_lock_irq(&gcwq->lock); 1728 spin_lock_irq(&gcwq->lock);
1593 if (need_to_create_worker(gcwq)) 1729 if (need_to_create_worker(pool))
1594 goto restart; 1730 goto restart;
1595 return true; 1731 return true;
1596} 1732}
1597 1733
1598/** 1734/**
1599 * maybe_destroy_worker - destroy workers which have been idle for a while 1735 * maybe_destroy_worker - destroy workers which have been idle for a while
1600 * @gcwq: gcwq to destroy workers for 1736 * @pool: pool to destroy workers for
1601 * 1737 *
1602 * Destroy @gcwq workers which have been idle for longer than 1738 * Destroy @pool workers which have been idle for longer than
1603 * IDLE_WORKER_TIMEOUT. 1739 * IDLE_WORKER_TIMEOUT.
1604 * 1740 *
1605 * LOCKING: 1741 * LOCKING:
@@ -1610,19 +1746,19 @@ restart:
1610 * false if no action was taken and gcwq->lock stayed locked, true 1746 * false if no action was taken and gcwq->lock stayed locked, true
1611 * otherwise. 1747 * otherwise.
1612 */ 1748 */
1613static bool maybe_destroy_workers(struct global_cwq *gcwq) 1749static bool maybe_destroy_workers(struct worker_pool *pool)
1614{ 1750{
1615 bool ret = false; 1751 bool ret = false;
1616 1752
1617 while (too_many_workers(gcwq)) { 1753 while (too_many_workers(pool)) {
1618 struct worker *worker; 1754 struct worker *worker;
1619 unsigned long expires; 1755 unsigned long expires;
1620 1756
1621 worker = list_entry(gcwq->idle_list.prev, struct worker, entry); 1757 worker = list_entry(pool->idle_list.prev, struct worker, entry);
1622 expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1758 expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1623 1759
1624 if (time_before(jiffies, expires)) { 1760 if (time_before(jiffies, expires)) {
1625 mod_timer(&gcwq->idle_timer, expires); 1761 mod_timer(&pool->idle_timer, expires);
1626 break; 1762 break;
1627 } 1763 }
1628 1764
@@ -1655,31 +1791,22 @@ static bool maybe_destroy_workers(struct global_cwq *gcwq)
1655 */ 1791 */
1656static bool manage_workers(struct worker *worker) 1792static bool manage_workers(struct worker *worker)
1657{ 1793{
1658 struct global_cwq *gcwq = worker->gcwq; 1794 struct worker_pool *pool = worker->pool;
1659 bool ret = false; 1795 bool ret = false;
1660 1796
1661 if (gcwq->flags & GCWQ_MANAGING_WORKERS) 1797 if (!mutex_trylock(&pool->manager_mutex))
1662 return ret; 1798 return ret;
1663 1799
1664 gcwq->flags &= ~GCWQ_MANAGE_WORKERS; 1800 pool->flags &= ~POOL_MANAGE_WORKERS;
1665 gcwq->flags |= GCWQ_MANAGING_WORKERS;
1666 1801
1667 /* 1802 /*
1668 * Destroy and then create so that may_start_working() is true 1803 * Destroy and then create so that may_start_working() is true
1669 * on return. 1804 * on return.
1670 */ 1805 */
1671 ret |= maybe_destroy_workers(gcwq); 1806 ret |= maybe_destroy_workers(pool);
1672 ret |= maybe_create_worker(gcwq); 1807 ret |= maybe_create_worker(pool);
1673
1674 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
1675
1676 /*
1677 * The trustee might be waiting to take over the manager
1678 * position, tell it we're done.
1679 */
1680 if (unlikely(gcwq->trustee))
1681 wake_up_all(&gcwq->trustee_wait);
1682 1808
1809 mutex_unlock(&pool->manager_mutex);
1683 return ret; 1810 return ret;
1684} 1811}
1685 1812
@@ -1728,10 +1855,9 @@ static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
1728{ 1855{
1729 struct work_struct *work = list_first_entry(&cwq->delayed_works, 1856 struct work_struct *work = list_first_entry(&cwq->delayed_works,
1730 struct work_struct, entry); 1857 struct work_struct, entry);
1731 struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq);
1732 1858
1733 trace_workqueue_activate_work(work); 1859 trace_workqueue_activate_work(work);
1734 move_linked_works(work, pos, NULL); 1860 move_linked_works(work, &cwq->pool->worklist, NULL);
1735 __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 1861 __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
1736 cwq->nr_active++; 1862 cwq->nr_active++;
1737} 1863}
@@ -1804,7 +1930,8 @@ __releases(&gcwq->lock)
1804__acquires(&gcwq->lock) 1930__acquires(&gcwq->lock)
1805{ 1931{
1806 struct cpu_workqueue_struct *cwq = get_work_cwq(work); 1932 struct cpu_workqueue_struct *cwq = get_work_cwq(work);
1807 struct global_cwq *gcwq = cwq->gcwq; 1933 struct worker_pool *pool = worker->pool;
1934 struct global_cwq *gcwq = pool->gcwq;
1808 struct hlist_head *bwh = busy_worker_head(gcwq, work); 1935 struct hlist_head *bwh = busy_worker_head(gcwq, work);
1809 bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; 1936 bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
1810 work_func_t f = work->func; 1937 work_func_t f = work->func;
@@ -1823,6 +1950,15 @@ __acquires(&gcwq->lock)
1823 lockdep_copy_map(&lockdep_map, &work->lockdep_map); 1950 lockdep_copy_map(&lockdep_map, &work->lockdep_map);
1824#endif 1951#endif
1825 /* 1952 /*
1953 * Ensure we're on the correct CPU. DISASSOCIATED test is
1954 * necessary to avoid spurious warnings from rescuers servicing the
1955 * unbound or a disassociated gcwq.
1956 */
1957 WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) &&
1958 !(gcwq->flags & GCWQ_DISASSOCIATED) &&
1959 raw_smp_processor_id() != gcwq->cpu);
1960
1961 /*
1826 * A single work shouldn't be executed concurrently by 1962 * A single work shouldn't be executed concurrently by
1827 * multiple workers on a single cpu. Check whether anyone is 1963 * multiple workers on a single cpu. Check whether anyone is
1828 * already processing the work. If so, defer the work to the 1964 * already processing the work. If so, defer the work to the
@@ -1846,27 +1982,19 @@ __acquires(&gcwq->lock)
1846 list_del_init(&work->entry); 1982 list_del_init(&work->entry);
1847 1983
1848 /* 1984 /*
1849 * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI,
1850 * wake up another worker; otherwise, clear HIGHPRI_PENDING.
1851 */
1852 if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) {
1853 struct work_struct *nwork = list_first_entry(&gcwq->worklist,
1854 struct work_struct, entry);
1855
1856 if (!list_empty(&gcwq->worklist) &&
1857 get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI)
1858 wake_up_worker(gcwq);
1859 else
1860 gcwq->flags &= ~GCWQ_HIGHPRI_PENDING;
1861 }
1862
1863 /*
1864 * CPU intensive works don't participate in concurrency 1985 * CPU intensive works don't participate in concurrency
1865 * management. They're the scheduler's responsibility. 1986 * management. They're the scheduler's responsibility.
1866 */ 1987 */
1867 if (unlikely(cpu_intensive)) 1988 if (unlikely(cpu_intensive))
1868 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 1989 worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
1869 1990
1991 /*
1992 * Unbound gcwq isn't concurrency managed and work items should be
1993 * executed ASAP. Wake up another worker if necessary.
1994 */
1995 if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
1996 wake_up_worker(pool);
1997
1870 spin_unlock_irq(&gcwq->lock); 1998 spin_unlock_irq(&gcwq->lock);
1871 1999
1872 work_clear_pending(work); 2000 work_clear_pending(work);
@@ -1939,28 +2067,38 @@ static void process_scheduled_works(struct worker *worker)
1939static int worker_thread(void *__worker) 2067static int worker_thread(void *__worker)
1940{ 2068{
1941 struct worker *worker = __worker; 2069 struct worker *worker = __worker;
1942 struct global_cwq *gcwq = worker->gcwq; 2070 struct worker_pool *pool = worker->pool;
2071 struct global_cwq *gcwq = pool->gcwq;
1943 2072
1944 /* tell the scheduler that this is a workqueue worker */ 2073 /* tell the scheduler that this is a workqueue worker */
1945 worker->task->flags |= PF_WQ_WORKER; 2074 worker->task->flags |= PF_WQ_WORKER;
1946woke_up: 2075woke_up:
1947 spin_lock_irq(&gcwq->lock); 2076 spin_lock_irq(&gcwq->lock);
1948 2077
1949 /* DIE can be set only while we're idle, checking here is enough */ 2078 /*
1950 if (worker->flags & WORKER_DIE) { 2079 * DIE can be set only while idle and REBIND set while busy has
2080 * @worker->rebind_work scheduled. Checking here is enough.
2081 */
2082 if (unlikely(worker->flags & (WORKER_REBIND | WORKER_DIE))) {
1951 spin_unlock_irq(&gcwq->lock); 2083 spin_unlock_irq(&gcwq->lock);
1952 worker->task->flags &= ~PF_WQ_WORKER; 2084
1953 return 0; 2085 if (worker->flags & WORKER_DIE) {
2086 worker->task->flags &= ~PF_WQ_WORKER;
2087 return 0;
2088 }
2089
2090 idle_worker_rebind(worker);
2091 goto woke_up;
1954 } 2092 }
1955 2093
1956 worker_leave_idle(worker); 2094 worker_leave_idle(worker);
1957recheck: 2095recheck:
1958 /* no more worker necessary? */ 2096 /* no more worker necessary? */
1959 if (!need_more_worker(gcwq)) 2097 if (!need_more_worker(pool))
1960 goto sleep; 2098 goto sleep;
1961 2099
1962 /* do we need to manage? */ 2100 /* do we need to manage? */
1963 if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) 2101 if (unlikely(!may_start_working(pool)) && manage_workers(worker))
1964 goto recheck; 2102 goto recheck;
1965 2103
1966 /* 2104 /*
@@ -1979,7 +2117,7 @@ recheck:
1979 2117
1980 do { 2118 do {
1981 struct work_struct *work = 2119 struct work_struct *work =
1982 list_first_entry(&gcwq->worklist, 2120 list_first_entry(&pool->worklist,
1983 struct work_struct, entry); 2121 struct work_struct, entry);
1984 2122
1985 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 2123 if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
@@ -1991,11 +2129,11 @@ recheck:
1991 move_linked_works(work, &worker->scheduled, NULL); 2129 move_linked_works(work, &worker->scheduled, NULL);
1992 process_scheduled_works(worker); 2130 process_scheduled_works(worker);
1993 } 2131 }
1994 } while (keep_working(gcwq)); 2132 } while (keep_working(pool));
1995 2133
1996 worker_set_flags(worker, WORKER_PREP, false); 2134 worker_set_flags(worker, WORKER_PREP, false);
1997sleep: 2135sleep:
1998 if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) 2136 if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker))
1999 goto recheck; 2137 goto recheck;
2000 2138
2001 /* 2139 /*
@@ -2053,14 +2191,15 @@ repeat:
2053 for_each_mayday_cpu(cpu, wq->mayday_mask) { 2191 for_each_mayday_cpu(cpu, wq->mayday_mask) {
2054 unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; 2192 unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
2055 struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); 2193 struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
2056 struct global_cwq *gcwq = cwq->gcwq; 2194 struct worker_pool *pool = cwq->pool;
2195 struct global_cwq *gcwq = pool->gcwq;
2057 struct work_struct *work, *n; 2196 struct work_struct *work, *n;
2058 2197
2059 __set_current_state(TASK_RUNNING); 2198 __set_current_state(TASK_RUNNING);
2060 mayday_clear_cpu(cpu, wq->mayday_mask); 2199 mayday_clear_cpu(cpu, wq->mayday_mask);
2061 2200
2062 /* migrate to the target cpu if possible */ 2201 /* migrate to the target cpu if possible */
2063 rescuer->gcwq = gcwq; 2202 rescuer->pool = pool;
2064 worker_maybe_bind_and_lock(rescuer); 2203 worker_maybe_bind_and_lock(rescuer);
2065 2204
2066 /* 2205 /*
@@ -2068,7 +2207,7 @@ repeat:
2068 * process'em. 2207 * process'em.
2069 */ 2208 */
2070 BUG_ON(!list_empty(&rescuer->scheduled)); 2209 BUG_ON(!list_empty(&rescuer->scheduled));
2071 list_for_each_entry_safe(work, n, &gcwq->worklist, entry) 2210 list_for_each_entry_safe(work, n, &pool->worklist, entry)
2072 if (get_work_cwq(work) == cwq) 2211 if (get_work_cwq(work) == cwq)
2073 move_linked_works(work, scheduled, &n); 2212 move_linked_works(work, scheduled, &n);
2074 2213
@@ -2079,8 +2218,8 @@ repeat:
2079 * regular worker; otherwise, we end up with 0 concurrency 2218 * regular worker; otherwise, we end up with 0 concurrency
2080 * and stalling the execution. 2219 * and stalling the execution.
2081 */ 2220 */
2082 if (keep_working(gcwq)) 2221 if (keep_working(pool))
2083 wake_up_worker(gcwq); 2222 wake_up_worker(pool);
2084 2223
2085 spin_unlock_irq(&gcwq->lock); 2224 spin_unlock_irq(&gcwq->lock);
2086 } 2225 }
@@ -2205,7 +2344,7 @@ static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
2205 2344
2206 for_each_cwq_cpu(cpu, wq) { 2345 for_each_cwq_cpu(cpu, wq) {
2207 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2346 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2208 struct global_cwq *gcwq = cwq->gcwq; 2347 struct global_cwq *gcwq = cwq->pool->gcwq;
2209 2348
2210 spin_lock_irq(&gcwq->lock); 2349 spin_lock_irq(&gcwq->lock);
2211 2350
@@ -2421,9 +2560,9 @@ reflush:
2421 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 2560 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
2422 bool drained; 2561 bool drained;
2423 2562
2424 spin_lock_irq(&cwq->gcwq->lock); 2563 spin_lock_irq(&cwq->pool->gcwq->lock);
2425 drained = !cwq->nr_active && list_empty(&cwq->delayed_works); 2564 drained = !cwq->nr_active && list_empty(&cwq->delayed_works);
2426 spin_unlock_irq(&cwq->gcwq->lock); 2565 spin_unlock_irq(&cwq->pool->gcwq->lock);
2427 2566
2428 if (drained) 2567 if (drained)
2429 continue; 2568 continue;
@@ -2463,7 +2602,7 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr,
2463 */ 2602 */
2464 smp_rmb(); 2603 smp_rmb();
2465 cwq = get_work_cwq(work); 2604 cwq = get_work_cwq(work);
2466 if (unlikely(!cwq || gcwq != cwq->gcwq)) 2605 if (unlikely(!cwq || gcwq != cwq->pool->gcwq))
2467 goto already_gone; 2606 goto already_gone;
2468 } else if (wait_executing) { 2607 } else if (wait_executing) {
2469 worker = find_worker_executing_work(gcwq, work); 2608 worker = find_worker_executing_work(gcwq, work);
@@ -2984,13 +3123,6 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
2984 if (flags & WQ_MEM_RECLAIM) 3123 if (flags & WQ_MEM_RECLAIM)
2985 flags |= WQ_RESCUER; 3124 flags |= WQ_RESCUER;
2986 3125
2987 /*
2988 * Unbound workqueues aren't concurrency managed and should be
2989 * dispatched to workers immediately.
2990 */
2991 if (flags & WQ_UNBOUND)
2992 flags |= WQ_HIGHPRI;
2993
2994 max_active = max_active ?: WQ_DFL_ACTIVE; 3126 max_active = max_active ?: WQ_DFL_ACTIVE;
2995 max_active = wq_clamp_max_active(max_active, flags, wq->name); 3127 max_active = wq_clamp_max_active(max_active, flags, wq->name);
2996 3128
@@ -3011,9 +3143,10 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
3011 for_each_cwq_cpu(cpu, wq) { 3143 for_each_cwq_cpu(cpu, wq) {
3012 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); 3144 struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
3013 struct global_cwq *gcwq = get_gcwq(cpu); 3145 struct global_cwq *gcwq = get_gcwq(cpu);
3146 int pool_idx = (bool)(flags & WQ_HIGHPRI);
3014 3147
3015 BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); 3148 BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
3016 cwq->gcwq = gcwq; 3149 cwq->pool = &gcwq->pools[pool_idx];
3017 cwq->wq = wq; 3150 cwq->wq = wq;
3018 cwq->flush_color = -1; 3151 cwq->flush_color = -1;
3019 cwq->max_active = max_active; 3152 cwq->max_active = max_active;
@@ -3225,369 +3358,143 @@ EXPORT_SYMBOL_GPL(work_busy);
3225 * gcwqs serve mix of short, long and very long running works making 3358 * gcwqs serve mix of short, long and very long running works making
3226 * blocked draining impractical. 3359 * blocked draining impractical.
3227 * 3360 *
3228 * This is solved by allowing a gcwq to be detached from CPU, running 3361 * This is solved by allowing a gcwq to be disassociated from the CPU
3229 * it with unbound (rogue) workers and allowing it to be reattached 3362 * running as an unbound one and allowing it to be reattached later if the
3230 * later if the cpu comes back online. A separate thread is created 3363 * cpu comes back online.
3231 * to govern a gcwq in such state and is called the trustee of the
3232 * gcwq.
3233 *
3234 * Trustee states and their descriptions.
3235 *
3236 * START Command state used on startup. On CPU_DOWN_PREPARE, a
3237 * new trustee is started with this state.
3238 *
3239 * IN_CHARGE Once started, trustee will enter this state after
3240 * assuming the manager role and making all existing
3241 * workers rogue. DOWN_PREPARE waits for trustee to
3242 * enter this state. After reaching IN_CHARGE, trustee
3243 * tries to execute the pending worklist until it's empty
3244 * and the state is set to BUTCHER, or the state is set
3245 * to RELEASE.
3246 *
3247 * BUTCHER Command state which is set by the cpu callback after
3248 * the cpu has went down. Once this state is set trustee
3249 * knows that there will be no new works on the worklist
3250 * and once the worklist is empty it can proceed to
3251 * killing idle workers.
3252 *
3253 * RELEASE Command state which is set by the cpu callback if the
3254 * cpu down has been canceled or it has come online
3255 * again. After recognizing this state, trustee stops
3256 * trying to drain or butcher and clears ROGUE, rebinds
3257 * all remaining workers back to the cpu and releases
3258 * manager role.
3259 *
3260 * DONE Trustee will enter this state after BUTCHER or RELEASE
3261 * is complete.
3262 *
3263 * trustee CPU draining
3264 * took over down complete
3265 * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
3266 * | | ^
3267 * | CPU is back online v return workers |
3268 * ----------------> RELEASE --------------
3269 */ 3364 */
3270 3365
3271/** 3366/* claim manager positions of all pools */
3272 * trustee_wait_event_timeout - timed event wait for trustee 3367static void gcwq_claim_management_and_lock(struct global_cwq *gcwq)
3273 * @cond: condition to wait for
3274 * @timeout: timeout in jiffies
3275 *
3276 * wait_event_timeout() for trustee to use. Handles locking and
3277 * checks for RELEASE request.
3278 *
3279 * CONTEXT:
3280 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3281 * multiple times. To be used by trustee.
3282 *
3283 * RETURNS:
3284 * Positive indicating left time if @cond is satisfied, 0 if timed
3285 * out, -1 if canceled.
3286 */
3287#define trustee_wait_event_timeout(cond, timeout) ({ \
3288 long __ret = (timeout); \
3289 while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \
3290 __ret) { \
3291 spin_unlock_irq(&gcwq->lock); \
3292 __wait_event_timeout(gcwq->trustee_wait, (cond) || \
3293 (gcwq->trustee_state == TRUSTEE_RELEASE), \
3294 __ret); \
3295 spin_lock_irq(&gcwq->lock); \
3296 } \
3297 gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \
3298})
3299
3300/**
3301 * trustee_wait_event - event wait for trustee
3302 * @cond: condition to wait for
3303 *
3304 * wait_event() for trustee to use. Automatically handles locking and
3305 * checks for CANCEL request.
3306 *
3307 * CONTEXT:
3308 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3309 * multiple times. To be used by trustee.
3310 *
3311 * RETURNS:
3312 * 0 if @cond is satisfied, -1 if canceled.
3313 */
3314#define trustee_wait_event(cond) ({ \
3315 long __ret1; \
3316 __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
3317 __ret1 < 0 ? -1 : 0; \
3318})
3319
3320static int __cpuinit trustee_thread(void *__gcwq)
3321{ 3368{
3322 struct global_cwq *gcwq = __gcwq; 3369 struct worker_pool *pool;
3323 struct worker *worker;
3324 struct work_struct *work;
3325 struct hlist_node *pos;
3326 long rc;
3327 int i;
3328
3329 BUG_ON(gcwq->cpu != smp_processor_id());
3330 3370
3371 for_each_worker_pool(pool, gcwq)
3372 mutex_lock_nested(&pool->manager_mutex, pool - gcwq->pools);
3331 spin_lock_irq(&gcwq->lock); 3373 spin_lock_irq(&gcwq->lock);
3332 /* 3374}
3333 * Claim the manager position and make all workers rogue.
3334 * Trustee must be bound to the target cpu and can't be
3335 * cancelled.
3336 */
3337 BUG_ON(gcwq->cpu != smp_processor_id());
3338 rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS));
3339 BUG_ON(rc < 0);
3340
3341 gcwq->flags |= GCWQ_MANAGING_WORKERS;
3342
3343 list_for_each_entry(worker, &gcwq->idle_list, entry)
3344 worker->flags |= WORKER_ROGUE;
3345 3375
3346 for_each_busy_worker(worker, i, pos, gcwq) 3376/* release manager positions */
3347 worker->flags |= WORKER_ROGUE; 3377static void gcwq_release_management_and_unlock(struct global_cwq *gcwq)
3378{
3379 struct worker_pool *pool;
3348 3380
3349 /*
3350 * Call schedule() so that we cross rq->lock and thus can
3351 * guarantee sched callbacks see the rogue flag. This is
3352 * necessary as scheduler callbacks may be invoked from other
3353 * cpus.
3354 */
3355 spin_unlock_irq(&gcwq->lock); 3381 spin_unlock_irq(&gcwq->lock);
3356 schedule(); 3382 for_each_worker_pool(pool, gcwq)
3357 spin_lock_irq(&gcwq->lock); 3383 mutex_unlock(&pool->manager_mutex);
3384}
3358 3385
3359 /* 3386static void gcwq_unbind_fn(struct work_struct *work)
3360 * Sched callbacks are disabled now. Zap nr_running. After 3387{
3361 * this, nr_running stays zero and need_more_worker() and 3388 struct global_cwq *gcwq = get_gcwq(smp_processor_id());
3362 * keep_working() are always true as long as the worklist is 3389 struct worker_pool *pool;
3363 * not empty. 3390 struct worker *worker;
3364 */ 3391 struct hlist_node *pos;
3365 atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); 3392 int i;
3366 3393
3367 spin_unlock_irq(&gcwq->lock); 3394 BUG_ON(gcwq->cpu != smp_processor_id());
3368 del_timer_sync(&gcwq->idle_timer);
3369 spin_lock_irq(&gcwq->lock);
3370 3395
3371 /* 3396 gcwq_claim_management_and_lock(gcwq);
3372 * We're now in charge. Notify and proceed to drain. We need
3373 * to keep the gcwq running during the whole CPU down
3374 * procedure as other cpu hotunplug callbacks may need to
3375 * flush currently running tasks.
3376 */
3377 gcwq->trustee_state = TRUSTEE_IN_CHARGE;
3378 wake_up_all(&gcwq->trustee_wait);
3379 3397
3380 /* 3398 /*
3381 * The original cpu is in the process of dying and may go away 3399 * We've claimed all manager positions. Make all workers unbound
3382 * anytime now. When that happens, we and all workers would 3400 * and set DISASSOCIATED. Before this, all workers except for the
3383 * be migrated to other cpus. Try draining any left work. We 3401 * ones which are still executing works from before the last CPU
3384 * want to get it over with ASAP - spam rescuers, wake up as 3402 * down must be on the cpu. After this, they may become diasporas.
3385 * many idlers as necessary and create new ones till the
3386 * worklist is empty. Note that if the gcwq is frozen, there
3387 * may be frozen works in freezable cwqs. Don't declare
3388 * completion while frozen.
3389 */ 3403 */
3390 while (gcwq->nr_workers != gcwq->nr_idle || 3404 for_each_worker_pool(pool, gcwq)
3391 gcwq->flags & GCWQ_FREEZING || 3405 list_for_each_entry(worker, &pool->idle_list, entry)
3392 gcwq->trustee_state == TRUSTEE_IN_CHARGE) { 3406 worker->flags |= WORKER_UNBOUND;
3393 int nr_works = 0;
3394
3395 list_for_each_entry(work, &gcwq->worklist, entry) {
3396 send_mayday(work);
3397 nr_works++;
3398 }
3399 3407
3400 list_for_each_entry(worker, &gcwq->idle_list, entry) { 3408 for_each_busy_worker(worker, i, pos, gcwq)
3401 if (!nr_works--) 3409 worker->flags |= WORKER_UNBOUND;
3402 break;
3403 wake_up_process(worker->task);
3404 }
3405 3410
3406 if (need_to_create_worker(gcwq)) { 3411 gcwq->flags |= GCWQ_DISASSOCIATED;
3407 spin_unlock_irq(&gcwq->lock);
3408 worker = create_worker(gcwq, false);
3409 spin_lock_irq(&gcwq->lock);
3410 if (worker) {
3411 worker->flags |= WORKER_ROGUE;
3412 start_worker(worker);
3413 }
3414 }
3415 3412
3416 /* give a breather */ 3413 gcwq_release_management_and_unlock(gcwq);
3417 if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0)
3418 break;
3419 }
3420 3414
3421 /* 3415 /*
3422 * Either all works have been scheduled and cpu is down, or 3416 * Call schedule() so that we cross rq->lock and thus can guarantee
3423 * cpu down has already been canceled. Wait for and butcher 3417 * sched callbacks see the %WORKER_UNBOUND flag. This is necessary
3424 * all workers till we're canceled. 3418 * as scheduler callbacks may be invoked from other cpus.
3425 */ 3419 */
3426 do { 3420 schedule();
3427 rc = trustee_wait_event(!list_empty(&gcwq->idle_list));
3428 while (!list_empty(&gcwq->idle_list))
3429 destroy_worker(list_first_entry(&gcwq->idle_list,
3430 struct worker, entry));
3431 } while (gcwq->nr_workers && rc >= 0);
3432 3421
3433 /* 3422 /*
3434 * At this point, either draining has completed and no worker 3423 * Sched callbacks are disabled now. Zap nr_running. After this,
3435 * is left, or cpu down has been canceled or the cpu is being 3424 * nr_running stays zero and need_more_worker() and keep_working()
3436 * brought back up. There shouldn't be any idle one left. 3425 * are always true as long as the worklist is not empty. @gcwq now
3437 * Tell the remaining busy ones to rebind once it finishes the 3426 * behaves as unbound (in terms of concurrency management) gcwq
3438 * currently scheduled works by scheduling the rebind_work. 3427 * which is served by workers tied to the CPU.
3428 *
3429 * On return from this function, the current worker would trigger
3430 * unbound chain execution of pending work items if other workers
3431 * didn't already.
3439 */ 3432 */
3440 WARN_ON(!list_empty(&gcwq->idle_list)); 3433 for_each_worker_pool(pool, gcwq)
3441 3434 atomic_set(get_pool_nr_running(pool), 0);
3442 for_each_busy_worker(worker, i, pos, gcwq) {
3443 struct work_struct *rebind_work = &worker->rebind_work;
3444
3445 /*
3446 * Rebind_work may race with future cpu hotplug
3447 * operations. Use a separate flag to mark that
3448 * rebinding is scheduled.
3449 */
3450 worker->flags |= WORKER_REBIND;
3451 worker->flags &= ~WORKER_ROGUE;
3452
3453 /* queue rebind_work, wq doesn't matter, use the default one */
3454 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT,
3455 work_data_bits(rebind_work)))
3456 continue;
3457
3458 debug_work_activate(rebind_work);
3459 insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work,
3460 worker->scheduled.next,
3461 work_color_to_flags(WORK_NO_COLOR));
3462 }
3463
3464 /* relinquish manager role */
3465 gcwq->flags &= ~GCWQ_MANAGING_WORKERS;
3466
3467 /* notify completion */
3468 gcwq->trustee = NULL;
3469 gcwq->trustee_state = TRUSTEE_DONE;
3470 wake_up_all(&gcwq->trustee_wait);
3471 spin_unlock_irq(&gcwq->lock);
3472 return 0;
3473} 3435}
3474 3436
3475/** 3437/*
3476 * wait_trustee_state - wait for trustee to enter the specified state 3438 * Workqueues should be brought up before normal priority CPU notifiers.
3477 * @gcwq: gcwq the trustee of interest belongs to 3439 * This will be registered high priority CPU notifier.
3478 * @state: target state to wait for
3479 *
3480 * Wait for the trustee to reach @state. DONE is already matched.
3481 *
3482 * CONTEXT:
3483 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3484 * multiple times. To be used by cpu_callback.
3485 */ 3440 */
3486static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) 3441static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb,
3487__releases(&gcwq->lock) 3442 unsigned long action,
3488__acquires(&gcwq->lock) 3443 void *hcpu)
3489{
3490 if (!(gcwq->trustee_state == state ||
3491 gcwq->trustee_state == TRUSTEE_DONE)) {
3492 spin_unlock_irq(&gcwq->lock);
3493 __wait_event(gcwq->trustee_wait,
3494 gcwq->trustee_state == state ||
3495 gcwq->trustee_state == TRUSTEE_DONE);
3496 spin_lock_irq(&gcwq->lock);
3497 }
3498}
3499
3500static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
3501 unsigned long action,
3502 void *hcpu)
3503{ 3444{
3504 unsigned int cpu = (unsigned long)hcpu; 3445 unsigned int cpu = (unsigned long)hcpu;
3505 struct global_cwq *gcwq = get_gcwq(cpu); 3446 struct global_cwq *gcwq = get_gcwq(cpu);
3506 struct task_struct *new_trustee = NULL; 3447 struct worker_pool *pool;
3507 struct worker *uninitialized_var(new_worker);
3508 unsigned long flags;
3509
3510 action &= ~CPU_TASKS_FROZEN;
3511 3448
3512 switch (action) { 3449 switch (action & ~CPU_TASKS_FROZEN) {
3513 case CPU_DOWN_PREPARE:
3514 new_trustee = kthread_create(trustee_thread, gcwq,
3515 "workqueue_trustee/%d\n", cpu);
3516 if (IS_ERR(new_trustee))
3517 return notifier_from_errno(PTR_ERR(new_trustee));
3518 kthread_bind(new_trustee, cpu);
3519 /* fall through */
3520 case CPU_UP_PREPARE: 3450 case CPU_UP_PREPARE:
3521 BUG_ON(gcwq->first_idle); 3451 for_each_worker_pool(pool, gcwq) {
3522 new_worker = create_worker(gcwq, false); 3452 struct worker *worker;
3523 if (!new_worker) {
3524 if (new_trustee)
3525 kthread_stop(new_trustee);
3526 return NOTIFY_BAD;
3527 }
3528 }
3529
3530 /* some are called w/ irq disabled, don't disturb irq status */
3531 spin_lock_irqsave(&gcwq->lock, flags);
3532 3453
3533 switch (action) { 3454 if (pool->nr_workers)
3534 case CPU_DOWN_PREPARE: 3455 continue;
3535 /* initialize trustee and tell it to acquire the gcwq */
3536 BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE);
3537 gcwq->trustee = new_trustee;
3538 gcwq->trustee_state = TRUSTEE_START;
3539 wake_up_process(gcwq->trustee);
3540 wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE);
3541 /* fall through */
3542 case CPU_UP_PREPARE:
3543 BUG_ON(gcwq->first_idle);
3544 gcwq->first_idle = new_worker;
3545 break;
3546 3456
3547 case CPU_DYING: 3457 worker = create_worker(pool);
3548 /* 3458 if (!worker)
3549 * Before this, the trustee and all workers except for 3459 return NOTIFY_BAD;
3550 * the ones which are still executing works from
3551 * before the last CPU down must be on the cpu. After
3552 * this, they'll all be diasporas.
3553 */
3554 gcwq->flags |= GCWQ_DISASSOCIATED;
3555 break;
3556 3460
3557 case CPU_POST_DEAD: 3461 spin_lock_irq(&gcwq->lock);
3558 gcwq->trustee_state = TRUSTEE_BUTCHER; 3462 start_worker(worker);
3559 /* fall through */ 3463 spin_unlock_irq(&gcwq->lock);
3560 case CPU_UP_CANCELED: 3464 }
3561 destroy_worker(gcwq->first_idle);
3562 gcwq->first_idle = NULL;
3563 break; 3465 break;
3564 3466
3565 case CPU_DOWN_FAILED: 3467 case CPU_DOWN_FAILED:
3566 case CPU_ONLINE: 3468 case CPU_ONLINE:
3469 gcwq_claim_management_and_lock(gcwq);
3567 gcwq->flags &= ~GCWQ_DISASSOCIATED; 3470 gcwq->flags &= ~GCWQ_DISASSOCIATED;
3568 if (gcwq->trustee_state != TRUSTEE_DONE) { 3471 rebind_workers(gcwq);
3569 gcwq->trustee_state = TRUSTEE_RELEASE; 3472 gcwq_release_management_and_unlock(gcwq);
3570 wake_up_process(gcwq->trustee);
3571 wait_trustee_state(gcwq, TRUSTEE_DONE);
3572 }
3573
3574 /*
3575 * Trustee is done and there might be no worker left.
3576 * Put the first_idle in and request a real manager to
3577 * take a look.
3578 */
3579 spin_unlock_irq(&gcwq->lock);
3580 kthread_bind(gcwq->first_idle->task, cpu);
3581 spin_lock_irq(&gcwq->lock);
3582 gcwq->flags |= GCWQ_MANAGE_WORKERS;
3583 start_worker(gcwq->first_idle);
3584 gcwq->first_idle = NULL;
3585 break; 3473 break;
3586 } 3474 }
3475 return NOTIFY_OK;
3476}
3587 3477
3588 spin_unlock_irqrestore(&gcwq->lock, flags); 3478/*
3479 * Workqueues should be brought down after normal priority CPU notifiers.
3480 * This will be registered as low priority CPU notifier.
3481 */
3482static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb,
3483 unsigned long action,
3484 void *hcpu)
3485{
3486 unsigned int cpu = (unsigned long)hcpu;
3487 struct work_struct unbind_work;
3589 3488
3590 return notifier_from_errno(0); 3489 switch (action & ~CPU_TASKS_FROZEN) {
3490 case CPU_DOWN_PREPARE:
3491 /* unbinding should happen on the local CPU */
3492 INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn);
3493 schedule_work_on(cpu, &unbind_work);
3494 flush_work(&unbind_work);
3495 break;
3496 }
3497 return NOTIFY_OK;
3591} 3498}
3592 3499
3593#ifdef CONFIG_SMP 3500#ifdef CONFIG_SMP
@@ -3746,6 +3653,7 @@ void thaw_workqueues(void)
3746 3653
3747 for_each_gcwq_cpu(cpu) { 3654 for_each_gcwq_cpu(cpu) {
3748 struct global_cwq *gcwq = get_gcwq(cpu); 3655 struct global_cwq *gcwq = get_gcwq(cpu);
3656 struct worker_pool *pool;
3749 struct workqueue_struct *wq; 3657 struct workqueue_struct *wq;
3750 3658
3751 spin_lock_irq(&gcwq->lock); 3659 spin_lock_irq(&gcwq->lock);
@@ -3767,7 +3675,8 @@ void thaw_workqueues(void)
3767 cwq_activate_first_delayed(cwq); 3675 cwq_activate_first_delayed(cwq);
3768 } 3676 }
3769 3677
3770 wake_up_worker(gcwq); 3678 for_each_worker_pool(pool, gcwq)
3679 wake_up_worker(pool);
3771 3680
3772 spin_unlock_irq(&gcwq->lock); 3681 spin_unlock_irq(&gcwq->lock);
3773 } 3682 }
@@ -3783,46 +3692,57 @@ static int __init init_workqueues(void)
3783 unsigned int cpu; 3692 unsigned int cpu;
3784 int i; 3693 int i;
3785 3694
3786 cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); 3695 cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
3696 cpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
3787 3697
3788 /* initialize gcwqs */ 3698 /* initialize gcwqs */
3789 for_each_gcwq_cpu(cpu) { 3699 for_each_gcwq_cpu(cpu) {
3790 struct global_cwq *gcwq = get_gcwq(cpu); 3700 struct global_cwq *gcwq = get_gcwq(cpu);
3701 struct worker_pool *pool;
3791 3702
3792 spin_lock_init(&gcwq->lock); 3703 spin_lock_init(&gcwq->lock);
3793 INIT_LIST_HEAD(&gcwq->worklist);
3794 gcwq->cpu = cpu; 3704 gcwq->cpu = cpu;
3795 gcwq->flags |= GCWQ_DISASSOCIATED; 3705 gcwq->flags |= GCWQ_DISASSOCIATED;
3796 3706
3797 INIT_LIST_HEAD(&gcwq->idle_list);
3798 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) 3707 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
3799 INIT_HLIST_HEAD(&gcwq->busy_hash[i]); 3708 INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
3800 3709
3801 init_timer_deferrable(&gcwq->idle_timer); 3710 for_each_worker_pool(pool, gcwq) {
3802 gcwq->idle_timer.function = idle_worker_timeout; 3711 pool->gcwq = gcwq;
3803 gcwq->idle_timer.data = (unsigned long)gcwq; 3712 INIT_LIST_HEAD(&pool->worklist);
3713 INIT_LIST_HEAD(&pool->idle_list);
3714
3715 init_timer_deferrable(&pool->idle_timer);
3716 pool->idle_timer.function = idle_worker_timeout;
3717 pool->idle_timer.data = (unsigned long)pool;
3804 3718
3805 setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, 3719 setup_timer(&pool->mayday_timer, gcwq_mayday_timeout,
3806 (unsigned long)gcwq); 3720 (unsigned long)pool);
3807 3721
3808 ida_init(&gcwq->worker_ida); 3722 mutex_init(&pool->manager_mutex);
3723 ida_init(&pool->worker_ida);
3724 }
3809 3725
3810 gcwq->trustee_state = TRUSTEE_DONE; 3726 init_waitqueue_head(&gcwq->rebind_hold);
3811 init_waitqueue_head(&gcwq->trustee_wait);
3812 } 3727 }
3813 3728
3814 /* create the initial worker */ 3729 /* create the initial worker */
3815 for_each_online_gcwq_cpu(cpu) { 3730 for_each_online_gcwq_cpu(cpu) {
3816 struct global_cwq *gcwq = get_gcwq(cpu); 3731 struct global_cwq *gcwq = get_gcwq(cpu);
3817 struct worker *worker; 3732 struct worker_pool *pool;
3818 3733
3819 if (cpu != WORK_CPU_UNBOUND) 3734 if (cpu != WORK_CPU_UNBOUND)
3820 gcwq->flags &= ~GCWQ_DISASSOCIATED; 3735 gcwq->flags &= ~GCWQ_DISASSOCIATED;
3821 worker = create_worker(gcwq, true); 3736
3822 BUG_ON(!worker); 3737 for_each_worker_pool(pool, gcwq) {
3823 spin_lock_irq(&gcwq->lock); 3738 struct worker *worker;
3824 start_worker(worker); 3739
3825 spin_unlock_irq(&gcwq->lock); 3740 worker = create_worker(pool);
3741 BUG_ON(!worker);
3742 spin_lock_irq(&gcwq->lock);
3743 start_worker(worker);
3744 spin_unlock_irq(&gcwq->lock);
3745 }
3826 } 3746 }
3827 3747
3828 system_wq = alloc_workqueue("events", 0, 0); 3748 system_wq = alloc_workqueue("events", 0, 0);
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-26 04:13:17 -0500