1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Basic worker thread pool for io_uring
4 *
5 * Copyright (C) 2019 Jens Axboe
6 *
7 */
8 #include <linux/kernel.h>
9 #include <linux/init.h>
10 #include <linux/errno.h>
11 #include <linux/sched/signal.h>
12 #include <linux/percpu.h>
13 #include <linux/slab.h>
14 #include <linux/rculist_nulls.h>
15 #include <linux/cpu.h>
16 #include <linux/task_work.h>
17 #include <linux/audit.h>
18 #include <linux/mmu_context.h>
19 #include <uapi/linux/io_uring.h>
20
21 #include "io-wq.h"
22 #include "slist.h"
23 #include "io_uring.h"
24
25 #define WORKER_IDLE_TIMEOUT (5 * HZ)
26
27 enum {
28 IO_WORKER_F_UP = 0, /* up and active */
29 IO_WORKER_F_RUNNING = 1, /* account as running */
30 IO_WORKER_F_FREE = 2, /* worker on free list */
31 IO_WORKER_F_BOUND = 3, /* is doing bounded work */
32 };
33
34 enum {
35 IO_WQ_BIT_EXIT = 0, /* wq exiting */
36 };
37
38 enum {
39 IO_ACCT_STALLED_BIT = 0, /* stalled on hash */
40 };
41
42 /*
43 * One for each thread in a wq pool
44 */
45 struct io_worker {
46 refcount_t ref;
47 int create_index;
48 unsigned long flags;
49 struct hlist_nulls_node nulls_node;
50 struct list_head all_list;
51 struct task_struct *task;
52 struct io_wq *wq;
53
54 struct io_wq_work *cur_work;
55 struct io_wq_work *next_work;
56 raw_spinlock_t lock;
57
58 struct completion ref_done;
59
60 unsigned long create_state;
61 struct callback_head create_work;
62
63 union {
64 struct rcu_head rcu;
65 struct work_struct work;
66 };
67 };
68
69 #if BITS_PER_LONG == 64
70 #define IO_WQ_HASH_ORDER 6
71 #else
72 #define IO_WQ_HASH_ORDER 5
73 #endif
74
75 #define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
76
77 struct io_wq_acct {
78 unsigned nr_workers;
79 unsigned max_workers;
80 int index;
81 atomic_t nr_running;
82 raw_spinlock_t lock;
83 struct io_wq_work_list work_list;
84 unsigned long flags;
85 };
86
87 enum {
88 IO_WQ_ACCT_BOUND,
89 IO_WQ_ACCT_UNBOUND,
90 IO_WQ_ACCT_NR,
91 };
92
93 /*
94 * Per io_wq state
95 */
96 struct io_wq {
97 unsigned long state;
98
99 free_work_fn *free_work;
100 io_wq_work_fn *do_work;
101
102 struct io_wq_hash *hash;
103
104 atomic_t worker_refs;
105 struct completion worker_done;
106
107 struct hlist_node cpuhp_node;
108
109 struct task_struct *task;
110
111 struct io_wq_acct acct[IO_WQ_ACCT_NR];
112
113 /* lock protects access to elements below */
114 raw_spinlock_t lock;
115
116 struct hlist_nulls_head free_list;
117 struct list_head all_list;
118
119 struct wait_queue_entry wait;
120
121 struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
122
123 cpumask_var_t cpu_mask;
124 };
125
126 static enum cpuhp_state io_wq_online;
127
128 struct io_cb_cancel_data {
129 work_cancel_fn *fn;
130 void *data;
131 int nr_running;
132 int nr_pending;
133 bool cancel_all;
134 };
135
136 static bool create_io_worker(struct io_wq *wq, int index);
137 static void io_wq_dec_running(struct io_worker *worker);
138 static bool io_acct_cancel_pending_work(struct io_wq *wq,
139 struct io_wq_acct *acct,
140 struct io_cb_cancel_data *match);
141 static void create_worker_cb(struct callback_head *cb);
142 static void io_wq_cancel_tw_create(struct io_wq *wq);
143
io_worker_get(struct io_worker * worker)144 static bool io_worker_get(struct io_worker *worker)
145 {
146 return refcount_inc_not_zero(&worker->ref);
147 }
148
io_worker_release(struct io_worker * worker)149 static void io_worker_release(struct io_worker *worker)
150 {
151 if (refcount_dec_and_test(&worker->ref))
152 complete(&worker->ref_done);
153 }
154
io_get_acct(struct io_wq * wq,bool bound)155 static inline struct io_wq_acct *io_get_acct(struct io_wq *wq, bool bound)
156 {
157 return &wq->acct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND];
158 }
159
io_work_get_acct(struct io_wq * wq,struct io_wq_work * work)160 static inline struct io_wq_acct *io_work_get_acct(struct io_wq *wq,
161 struct io_wq_work *work)
162 {
163 return io_get_acct(wq, !(work->flags & IO_WQ_WORK_UNBOUND));
164 }
165
io_wq_get_acct(struct io_worker * worker)166 static inline struct io_wq_acct *io_wq_get_acct(struct io_worker *worker)
167 {
168 return io_get_acct(worker->wq, test_bit(IO_WORKER_F_BOUND, &worker->flags));
169 }
170
io_worker_ref_put(struct io_wq * wq)171 static void io_worker_ref_put(struct io_wq *wq)
172 {
173 if (atomic_dec_and_test(&wq->worker_refs))
174 complete(&wq->worker_done);
175 }
176
io_wq_worker_stopped(void)177 bool io_wq_worker_stopped(void)
178 {
179 struct io_worker *worker = current->worker_private;
180
181 if (WARN_ON_ONCE(!io_wq_current_is_worker()))
182 return true;
183
184 return test_bit(IO_WQ_BIT_EXIT, &worker->wq->state);
185 }
186
io_worker_cancel_cb(struct io_worker * worker)187 static void io_worker_cancel_cb(struct io_worker *worker)
188 {
189 struct io_wq_acct *acct = io_wq_get_acct(worker);
190 struct io_wq *wq = worker->wq;
191
192 atomic_dec(&acct->nr_running);
193 raw_spin_lock(&wq->lock);
194 acct->nr_workers--;
195 raw_spin_unlock(&wq->lock);
196 io_worker_ref_put(wq);
197 clear_bit_unlock(0, &worker->create_state);
198 io_worker_release(worker);
199 }
200
io_task_worker_match(struct callback_head * cb,void * data)201 static bool io_task_worker_match(struct callback_head *cb, void *data)
202 {
203 struct io_worker *worker;
204
205 if (cb->func != create_worker_cb)
206 return false;
207 worker = container_of(cb, struct io_worker, create_work);
208 return worker == data;
209 }
210
io_worker_exit(struct io_worker * worker)211 static void io_worker_exit(struct io_worker *worker)
212 {
213 struct io_wq *wq = worker->wq;
214
215 while (1) {
216 struct callback_head *cb = task_work_cancel_match(wq->task,
217 io_task_worker_match, worker);
218
219 if (!cb)
220 break;
221 io_worker_cancel_cb(worker);
222 }
223
224 io_worker_release(worker);
225 wait_for_completion(&worker->ref_done);
226
227 raw_spin_lock(&wq->lock);
228 if (test_bit(IO_WORKER_F_FREE, &worker->flags))
229 hlist_nulls_del_rcu(&worker->nulls_node);
230 list_del_rcu(&worker->all_list);
231 raw_spin_unlock(&wq->lock);
232 io_wq_dec_running(worker);
233 /*
234 * this worker is a goner, clear ->worker_private to avoid any
235 * inc/dec running calls that could happen as part of exit from
236 * touching 'worker'.
237 */
238 current->worker_private = NULL;
239
240 kfree_rcu(worker, rcu);
241 io_worker_ref_put(wq);
242 do_exit(0);
243 }
244
__io_acct_run_queue(struct io_wq_acct * acct)245 static inline bool __io_acct_run_queue(struct io_wq_acct *acct)
246 {
247 return !test_bit(IO_ACCT_STALLED_BIT, &acct->flags) &&
248 !wq_list_empty(&acct->work_list);
249 }
250
251 /*
252 * If there's work to do, returns true with acct->lock acquired. If not,
253 * returns false with no lock held.
254 */
io_acct_run_queue(struct io_wq_acct * acct)255 static inline bool io_acct_run_queue(struct io_wq_acct *acct)
256 __acquires(&acct->lock)
257 {
258 raw_spin_lock(&acct->lock);
259 if (__io_acct_run_queue(acct))
260 return true;
261
262 raw_spin_unlock(&acct->lock);
263 return false;
264 }
265
266 /*
267 * Check head of free list for an available worker. If one isn't available,
268 * caller must create one.
269 */
io_wq_activate_free_worker(struct io_wq * wq,struct io_wq_acct * acct)270 static bool io_wq_activate_free_worker(struct io_wq *wq,
271 struct io_wq_acct *acct)
272 __must_hold(RCU)
273 {
274 struct hlist_nulls_node *n;
275 struct io_worker *worker;
276
277 /*
278 * Iterate free_list and see if we can find an idle worker to
279 * activate. If a given worker is on the free_list but in the process
280 * of exiting, keep trying.
281 */
282 hlist_nulls_for_each_entry_rcu(worker, n, &wq->free_list, nulls_node) {
283 if (!io_worker_get(worker))
284 continue;
285 if (io_wq_get_acct(worker) != acct) {
286 io_worker_release(worker);
287 continue;
288 }
289 /*
290 * If the worker is already running, it's either already
291 * starting work or finishing work. In either case, if it does
292 * to go sleep, we'll kick off a new task for this work anyway.
293 */
294 wake_up_process(worker->task);
295 io_worker_release(worker);
296 return true;
297 }
298
299 return false;
300 }
301
302 /*
303 * We need a worker. If we find a free one, we're good. If not, and we're
304 * below the max number of workers, create one.
305 */
io_wq_create_worker(struct io_wq * wq,struct io_wq_acct * acct)306 static bool io_wq_create_worker(struct io_wq *wq, struct io_wq_acct *acct)
307 {
308 /*
309 * Most likely an attempt to queue unbounded work on an io_wq that
310 * wasn't setup with any unbounded workers.
311 */
312 if (unlikely(!acct->max_workers))
313 pr_warn_once("io-wq is not configured for unbound workers");
314
315 raw_spin_lock(&wq->lock);
316 if (acct->nr_workers >= acct->max_workers) {
317 raw_spin_unlock(&wq->lock);
318 return true;
319 }
320 acct->nr_workers++;
321 raw_spin_unlock(&wq->lock);
322 atomic_inc(&acct->nr_running);
323 atomic_inc(&wq->worker_refs);
324 return create_io_worker(wq, acct->index);
325 }
326
io_wq_inc_running(struct io_worker * worker)327 static void io_wq_inc_running(struct io_worker *worker)
328 {
329 struct io_wq_acct *acct = io_wq_get_acct(worker);
330
331 atomic_inc(&acct->nr_running);
332 }
333
create_worker_cb(struct callback_head * cb)334 static void create_worker_cb(struct callback_head *cb)
335 {
336 struct io_worker *worker;
337 struct io_wq *wq;
338
339 struct io_wq_acct *acct;
340 bool do_create = false;
341
342 worker = container_of(cb, struct io_worker, create_work);
343 wq = worker->wq;
344 acct = &wq->acct[worker->create_index];
345 raw_spin_lock(&wq->lock);
346
347 if (acct->nr_workers < acct->max_workers) {
348 acct->nr_workers++;
349 do_create = true;
350 }
351 raw_spin_unlock(&wq->lock);
352 if (do_create) {
353 create_io_worker(wq, worker->create_index);
354 } else {
355 atomic_dec(&acct->nr_running);
356 io_worker_ref_put(wq);
357 }
358 clear_bit_unlock(0, &worker->create_state);
359 io_worker_release(worker);
360 }
361
io_queue_worker_create(struct io_worker * worker,struct io_wq_acct * acct,task_work_func_t func)362 static bool io_queue_worker_create(struct io_worker *worker,
363 struct io_wq_acct *acct,
364 task_work_func_t func)
365 {
366 struct io_wq *wq = worker->wq;
367
368 /* raced with exit, just ignore create call */
369 if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
370 goto fail;
371 if (!io_worker_get(worker))
372 goto fail;
373 /*
374 * create_state manages ownership of create_work/index. We should
375 * only need one entry per worker, as the worker going to sleep
376 * will trigger the condition, and waking will clear it once it
377 * runs the task_work.
378 */
379 if (test_bit(0, &worker->create_state) ||
380 test_and_set_bit_lock(0, &worker->create_state))
381 goto fail_release;
382
383 atomic_inc(&wq->worker_refs);
384 init_task_work(&worker->create_work, func);
385 worker->create_index = acct->index;
386 if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
387 /*
388 * EXIT may have been set after checking it above, check after
389 * adding the task_work and remove any creation item if it is
390 * now set. wq exit does that too, but we can have added this
391 * work item after we canceled in io_wq_exit_workers().
392 */
393 if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
394 io_wq_cancel_tw_create(wq);
395 io_worker_ref_put(wq);
396 return true;
397 }
398 io_worker_ref_put(wq);
399 clear_bit_unlock(0, &worker->create_state);
400 fail_release:
401 io_worker_release(worker);
402 fail:
403 atomic_dec(&acct->nr_running);
404 io_worker_ref_put(wq);
405 return false;
406 }
407
io_wq_dec_running(struct io_worker * worker)408 static void io_wq_dec_running(struct io_worker *worker)
409 {
410 struct io_wq_acct *acct = io_wq_get_acct(worker);
411 struct io_wq *wq = worker->wq;
412
413 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
414 return;
415
416 if (!atomic_dec_and_test(&acct->nr_running))
417 return;
418 if (!io_acct_run_queue(acct))
419 return;
420
421 raw_spin_unlock(&acct->lock);
422 atomic_inc(&acct->nr_running);
423 atomic_inc(&wq->worker_refs);
424 io_queue_worker_create(worker, acct, create_worker_cb);
425 }
426
427 /*
428 * Worker will start processing some work. Move it to the busy list, if
429 * it's currently on the freelist
430 */
__io_worker_busy(struct io_wq * wq,struct io_worker * worker)431 static void __io_worker_busy(struct io_wq *wq, struct io_worker *worker)
432 {
433 if (test_bit(IO_WORKER_F_FREE, &worker->flags)) {
434 clear_bit(IO_WORKER_F_FREE, &worker->flags);
435 raw_spin_lock(&wq->lock);
436 hlist_nulls_del_init_rcu(&worker->nulls_node);
437 raw_spin_unlock(&wq->lock);
438 }
439 }
440
441 /*
442 * No work, worker going to sleep. Move to freelist.
443 */
__io_worker_idle(struct io_wq * wq,struct io_worker * worker)444 static void __io_worker_idle(struct io_wq *wq, struct io_worker *worker)
445 __must_hold(wq->lock)
446 {
447 if (!test_bit(IO_WORKER_F_FREE, &worker->flags)) {
448 set_bit(IO_WORKER_F_FREE, &worker->flags);
449 hlist_nulls_add_head_rcu(&worker->nulls_node, &wq->free_list);
450 }
451 }
452
io_get_work_hash(struct io_wq_work * work)453 static inline unsigned int io_get_work_hash(struct io_wq_work *work)
454 {
455 return work->flags >> IO_WQ_HASH_SHIFT;
456 }
457
io_wait_on_hash(struct io_wq * wq,unsigned int hash)458 static bool io_wait_on_hash(struct io_wq *wq, unsigned int hash)
459 {
460 bool ret = false;
461
462 spin_lock_irq(&wq->hash->wait.lock);
463 if (list_empty(&wq->wait.entry)) {
464 __add_wait_queue(&wq->hash->wait, &wq->wait);
465 if (!test_bit(hash, &wq->hash->map)) {
466 __set_current_state(TASK_RUNNING);
467 list_del_init(&wq->wait.entry);
468 ret = true;
469 }
470 }
471 spin_unlock_irq(&wq->hash->wait.lock);
472 return ret;
473 }
474
io_get_next_work(struct io_wq_acct * acct,struct io_worker * worker)475 static struct io_wq_work *io_get_next_work(struct io_wq_acct *acct,
476 struct io_worker *worker)
477 __must_hold(acct->lock)
478 {
479 struct io_wq_work_node *node, *prev;
480 struct io_wq_work *work, *tail;
481 unsigned int stall_hash = -1U;
482 struct io_wq *wq = worker->wq;
483
484 wq_list_for_each(node, prev, &acct->work_list) {
485 unsigned int hash;
486
487 work = container_of(node, struct io_wq_work, list);
488
489 /* not hashed, can run anytime */
490 if (!io_wq_is_hashed(work)) {
491 wq_list_del(&acct->work_list, node, prev);
492 return work;
493 }
494
495 hash = io_get_work_hash(work);
496 /* all items with this hash lie in [work, tail] */
497 tail = wq->hash_tail[hash];
498
499 /* hashed, can run if not already running */
500 if (!test_and_set_bit(hash, &wq->hash->map)) {
501 wq->hash_tail[hash] = NULL;
502 wq_list_cut(&acct->work_list, &tail->list, prev);
503 return work;
504 }
505 if (stall_hash == -1U)
506 stall_hash = hash;
507 /* fast forward to a next hash, for-each will fix up @prev */
508 node = &tail->list;
509 }
510
511 if (stall_hash != -1U) {
512 bool unstalled;
513
514 /*
515 * Set this before dropping the lock to avoid racing with new
516 * work being added and clearing the stalled bit.
517 */
518 set_bit(IO_ACCT_STALLED_BIT, &acct->flags);
519 raw_spin_unlock(&acct->lock);
520 unstalled = io_wait_on_hash(wq, stall_hash);
521 raw_spin_lock(&acct->lock);
522 if (unstalled) {
523 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
524 if (wq_has_sleeper(&wq->hash->wait))
525 wake_up(&wq->hash->wait);
526 }
527 }
528
529 return NULL;
530 }
531
io_assign_current_work(struct io_worker * worker,struct io_wq_work * work)532 static void io_assign_current_work(struct io_worker *worker,
533 struct io_wq_work *work)
534 {
535 if (work) {
536 io_run_task_work();
537 cond_resched();
538 }
539
540 raw_spin_lock(&worker->lock);
541 worker->cur_work = work;
542 worker->next_work = NULL;
543 raw_spin_unlock(&worker->lock);
544 }
545
546 /*
547 * Called with acct->lock held, drops it before returning
548 */
io_worker_handle_work(struct io_wq_acct * acct,struct io_worker * worker)549 static void io_worker_handle_work(struct io_wq_acct *acct,
550 struct io_worker *worker)
551 __releases(&acct->lock)
552 {
553 struct io_wq *wq = worker->wq;
554 bool do_kill = test_bit(IO_WQ_BIT_EXIT, &wq->state);
555
556 do {
557 struct io_wq_work *work;
558
559 /*
560 * If we got some work, mark us as busy. If we didn't, but
561 * the list isn't empty, it means we stalled on hashed work.
562 * Mark us stalled so we don't keep looking for work when we
563 * can't make progress, any work completion or insertion will
564 * clear the stalled flag.
565 */
566 work = io_get_next_work(acct, worker);
567 if (work) {
568 /*
569 * Make sure cancelation can find this, even before
570 * it becomes the active work. That avoids a window
571 * where the work has been removed from our general
572 * work list, but isn't yet discoverable as the
573 * current work item for this worker.
574 */
575 raw_spin_lock(&worker->lock);
576 worker->next_work = work;
577 raw_spin_unlock(&worker->lock);
578 }
579
580 raw_spin_unlock(&acct->lock);
581
582 if (!work)
583 break;
584
585 __io_worker_busy(wq, worker);
586
587 io_assign_current_work(worker, work);
588 __set_current_state(TASK_RUNNING);
589
590 /* handle a whole dependent link */
591 do {
592 struct io_wq_work *next_hashed, *linked;
593 unsigned int hash = io_get_work_hash(work);
594
595 next_hashed = wq_next_work(work);
596
597 if (unlikely(do_kill) && (work->flags & IO_WQ_WORK_UNBOUND))
598 work->flags |= IO_WQ_WORK_CANCEL;
599 wq->do_work(work);
600 io_assign_current_work(worker, NULL);
601
602 linked = wq->free_work(work);
603 work = next_hashed;
604 if (!work && linked && !io_wq_is_hashed(linked)) {
605 work = linked;
606 linked = NULL;
607 }
608 io_assign_current_work(worker, work);
609 if (linked)
610 io_wq_enqueue(wq, linked);
611
612 if (hash != -1U && !next_hashed) {
613 /* serialize hash clear with wake_up() */
614 spin_lock_irq(&wq->hash->wait.lock);
615 clear_bit(hash, &wq->hash->map);
616 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
617 spin_unlock_irq(&wq->hash->wait.lock);
618 if (wq_has_sleeper(&wq->hash->wait))
619 wake_up(&wq->hash->wait);
620 }
621 } while (work);
622
623 if (!__io_acct_run_queue(acct))
624 break;
625 raw_spin_lock(&acct->lock);
626 } while (1);
627 }
628
io_wq_worker(void * data)629 static int io_wq_worker(void *data)
630 {
631 struct io_worker *worker = data;
632 struct io_wq_acct *acct = io_wq_get_acct(worker);
633 struct io_wq *wq = worker->wq;
634 bool exit_mask = false, last_timeout = false;
635 char buf[TASK_COMM_LEN];
636
637 set_mask_bits(&worker->flags, 0,
638 BIT(IO_WORKER_F_UP) | BIT(IO_WORKER_F_RUNNING));
639
640 snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid);
641 set_task_comm(current, buf);
642
643 while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
644 long ret;
645
646 set_current_state(TASK_INTERRUPTIBLE);
647
648 /*
649 * If we have work to do, io_acct_run_queue() returns with
650 * the acct->lock held. If not, it will drop it.
651 */
652 while (io_acct_run_queue(acct))
653 io_worker_handle_work(acct, worker);
654
655 raw_spin_lock(&wq->lock);
656 /*
657 * Last sleep timed out. Exit if we're not the last worker,
658 * or if someone modified our affinity.
659 */
660 if (last_timeout && (exit_mask || acct->nr_workers > 1)) {
661 acct->nr_workers--;
662 raw_spin_unlock(&wq->lock);
663 __set_current_state(TASK_RUNNING);
664 break;
665 }
666 last_timeout = false;
667 __io_worker_idle(wq, worker);
668 raw_spin_unlock(&wq->lock);
669 if (io_run_task_work())
670 continue;
671 ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
672 if (signal_pending(current)) {
673 struct ksignal ksig;
674
675 if (!get_signal(&ksig))
676 continue;
677 break;
678 }
679 if (!ret) {
680 last_timeout = true;
681 exit_mask = !cpumask_test_cpu(raw_smp_processor_id(),
682 wq->cpu_mask);
683 }
684 }
685
686 if (test_bit(IO_WQ_BIT_EXIT, &wq->state) && io_acct_run_queue(acct))
687 io_worker_handle_work(acct, worker);
688
689 io_worker_exit(worker);
690 return 0;
691 }
692
693 /*
694 * Called when a worker is scheduled in. Mark us as currently running.
695 */
io_wq_worker_running(struct task_struct * tsk)696 void io_wq_worker_running(struct task_struct *tsk)
697 {
698 struct io_worker *worker = tsk->worker_private;
699
700 if (!worker)
701 return;
702 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
703 return;
704 if (test_bit(IO_WORKER_F_RUNNING, &worker->flags))
705 return;
706 set_bit(IO_WORKER_F_RUNNING, &worker->flags);
707 io_wq_inc_running(worker);
708 }
709
710 /*
711 * Called when worker is going to sleep. If there are no workers currently
712 * running and we have work pending, wake up a free one or create a new one.
713 */
io_wq_worker_sleeping(struct task_struct * tsk)714 void io_wq_worker_sleeping(struct task_struct *tsk)
715 {
716 struct io_worker *worker = tsk->worker_private;
717
718 if (!worker)
719 return;
720 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
721 return;
722 if (!test_bit(IO_WORKER_F_RUNNING, &worker->flags))
723 return;
724
725 clear_bit(IO_WORKER_F_RUNNING, &worker->flags);
726 io_wq_dec_running(worker);
727 }
728
io_init_new_worker(struct io_wq * wq,struct io_worker * worker,struct task_struct * tsk)729 static void io_init_new_worker(struct io_wq *wq, struct io_worker *worker,
730 struct task_struct *tsk)
731 {
732 tsk->worker_private = worker;
733 worker->task = tsk;
734 set_cpus_allowed_ptr(tsk, wq->cpu_mask);
735
736 raw_spin_lock(&wq->lock);
737 hlist_nulls_add_head_rcu(&worker->nulls_node, &wq->free_list);
738 list_add_tail_rcu(&worker->all_list, &wq->all_list);
739 set_bit(IO_WORKER_F_FREE, &worker->flags);
740 raw_spin_unlock(&wq->lock);
741 wake_up_new_task(tsk);
742 }
743
io_wq_work_match_all(struct io_wq_work * work,void * data)744 static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
745 {
746 return true;
747 }
748
io_should_retry_thread(long err)749 static inline bool io_should_retry_thread(long err)
750 {
751 /*
752 * Prevent perpetual task_work retry, if the task (or its group) is
753 * exiting.
754 */
755 if (fatal_signal_pending(current))
756 return false;
757
758 switch (err) {
759 case -EAGAIN:
760 case -ERESTARTSYS:
761 case -ERESTARTNOINTR:
762 case -ERESTARTNOHAND:
763 return true;
764 default:
765 return false;
766 }
767 }
768
create_worker_cont(struct callback_head * cb)769 static void create_worker_cont(struct callback_head *cb)
770 {
771 struct io_worker *worker;
772 struct task_struct *tsk;
773 struct io_wq *wq;
774
775 worker = container_of(cb, struct io_worker, create_work);
776 clear_bit_unlock(0, &worker->create_state);
777 wq = worker->wq;
778 tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE);
779 if (!IS_ERR(tsk)) {
780 io_init_new_worker(wq, worker, tsk);
781 io_worker_release(worker);
782 return;
783 } else if (!io_should_retry_thread(PTR_ERR(tsk))) {
784 struct io_wq_acct *acct = io_wq_get_acct(worker);
785
786 atomic_dec(&acct->nr_running);
787 raw_spin_lock(&wq->lock);
788 acct->nr_workers--;
789 if (!acct->nr_workers) {
790 struct io_cb_cancel_data match = {
791 .fn = io_wq_work_match_all,
792 .cancel_all = true,
793 };
794
795 raw_spin_unlock(&wq->lock);
796 while (io_acct_cancel_pending_work(wq, acct, &match))
797 ;
798 } else {
799 raw_spin_unlock(&wq->lock);
800 }
801 io_worker_ref_put(wq);
802 kfree(worker);
803 return;
804 }
805
806 /* re-create attempts grab a new worker ref, drop the existing one */
807 io_worker_release(worker);
808 schedule_work(&worker->work);
809 }
810
io_workqueue_create(struct work_struct * work)811 static void io_workqueue_create(struct work_struct *work)
812 {
813 struct io_worker *worker = container_of(work, struct io_worker, work);
814 struct io_wq_acct *acct = io_wq_get_acct(worker);
815
816 if (!io_queue_worker_create(worker, acct, create_worker_cont))
817 kfree(worker);
818 }
819
create_io_worker(struct io_wq * wq,int index)820 static bool create_io_worker(struct io_wq *wq, int index)
821 {
822 struct io_wq_acct *acct = &wq->acct[index];
823 struct io_worker *worker;
824 struct task_struct *tsk;
825
826 __set_current_state(TASK_RUNNING);
827
828 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
829 if (!worker) {
830 fail:
831 atomic_dec(&acct->nr_running);
832 raw_spin_lock(&wq->lock);
833 acct->nr_workers--;
834 raw_spin_unlock(&wq->lock);
835 io_worker_ref_put(wq);
836 return false;
837 }
838
839 refcount_set(&worker->ref, 1);
840 worker->wq = wq;
841 raw_spin_lock_init(&worker->lock);
842 init_completion(&worker->ref_done);
843
844 if (index == IO_WQ_ACCT_BOUND)
845 set_bit(IO_WORKER_F_BOUND, &worker->flags);
846
847 tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE);
848 if (!IS_ERR(tsk)) {
849 io_init_new_worker(wq, worker, tsk);
850 } else if (!io_should_retry_thread(PTR_ERR(tsk))) {
851 kfree(worker);
852 goto fail;
853 } else {
854 INIT_WORK(&worker->work, io_workqueue_create);
855 schedule_work(&worker->work);
856 }
857
858 return true;
859 }
860
861 /*
862 * Iterate the passed in list and call the specific function for each
863 * worker that isn't exiting
864 */
io_wq_for_each_worker(struct io_wq * wq,bool (* func)(struct io_worker *,void *),void * data)865 static bool io_wq_for_each_worker(struct io_wq *wq,
866 bool (*func)(struct io_worker *, void *),
867 void *data)
868 {
869 struct io_worker *worker;
870 bool ret = false;
871
872 list_for_each_entry_rcu(worker, &wq->all_list, all_list) {
873 if (io_worker_get(worker)) {
874 /* no task if node is/was offline */
875 if (worker->task)
876 ret = func(worker, data);
877 io_worker_release(worker);
878 if (ret)
879 break;
880 }
881 }
882
883 return ret;
884 }
885
io_wq_worker_wake(struct io_worker * worker,void * data)886 static bool io_wq_worker_wake(struct io_worker *worker, void *data)
887 {
888 __set_notify_signal(worker->task);
889 wake_up_process(worker->task);
890 return false;
891 }
892
io_run_cancel(struct io_wq_work * work,struct io_wq * wq)893 static void io_run_cancel(struct io_wq_work *work, struct io_wq *wq)
894 {
895 do {
896 work->flags |= IO_WQ_WORK_CANCEL;
897 wq->do_work(work);
898 work = wq->free_work(work);
899 } while (work);
900 }
901
io_wq_insert_work(struct io_wq * wq,struct io_wq_work * work)902 static void io_wq_insert_work(struct io_wq *wq, struct io_wq_work *work)
903 {
904 struct io_wq_acct *acct = io_work_get_acct(wq, work);
905 unsigned int hash;
906 struct io_wq_work *tail;
907
908 if (!io_wq_is_hashed(work)) {
909 append:
910 wq_list_add_tail(&work->list, &acct->work_list);
911 return;
912 }
913
914 hash = io_get_work_hash(work);
915 tail = wq->hash_tail[hash];
916 wq->hash_tail[hash] = work;
917 if (!tail)
918 goto append;
919
920 wq_list_add_after(&work->list, &tail->list, &acct->work_list);
921 }
922
io_wq_work_match_item(struct io_wq_work * work,void * data)923 static bool io_wq_work_match_item(struct io_wq_work *work, void *data)
924 {
925 return work == data;
926 }
927
io_wq_enqueue(struct io_wq * wq,struct io_wq_work * work)928 void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
929 {
930 struct io_wq_acct *acct = io_work_get_acct(wq, work);
931 unsigned long work_flags = work->flags;
932 struct io_cb_cancel_data match = {
933 .fn = io_wq_work_match_item,
934 .data = work,
935 .cancel_all = false,
936 };
937 bool do_create;
938
939 /*
940 * If io-wq is exiting for this task, or if the request has explicitly
941 * been marked as one that should not get executed, cancel it here.
942 */
943 if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
944 (work->flags & IO_WQ_WORK_CANCEL)) {
945 io_run_cancel(work, wq);
946 return;
947 }
948
949 raw_spin_lock(&acct->lock);
950 io_wq_insert_work(wq, work);
951 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
952 raw_spin_unlock(&acct->lock);
953
954 rcu_read_lock();
955 do_create = !io_wq_activate_free_worker(wq, acct);
956 rcu_read_unlock();
957
958 if (do_create && ((work_flags & IO_WQ_WORK_CONCURRENT) ||
959 !atomic_read(&acct->nr_running))) {
960 bool did_create;
961
962 did_create = io_wq_create_worker(wq, acct);
963 if (likely(did_create))
964 return;
965
966 raw_spin_lock(&wq->lock);
967 if (acct->nr_workers) {
968 raw_spin_unlock(&wq->lock);
969 return;
970 }
971 raw_spin_unlock(&wq->lock);
972
973 /* fatal condition, failed to create the first worker */
974 io_acct_cancel_pending_work(wq, acct, &match);
975 }
976 }
977
978 /*
979 * Work items that hash to the same value will not be done in parallel.
980 * Used to limit concurrent writes, generally hashed by inode.
981 */
io_wq_hash_work(struct io_wq_work * work,void * val)982 void io_wq_hash_work(struct io_wq_work *work, void *val)
983 {
984 unsigned int bit;
985
986 bit = hash_ptr(val, IO_WQ_HASH_ORDER);
987 work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
988 }
989
__io_wq_worker_cancel(struct io_worker * worker,struct io_cb_cancel_data * match,struct io_wq_work * work)990 static bool __io_wq_worker_cancel(struct io_worker *worker,
991 struct io_cb_cancel_data *match,
992 struct io_wq_work *work)
993 {
994 if (work && match->fn(work, match->data)) {
995 work->flags |= IO_WQ_WORK_CANCEL;
996 __set_notify_signal(worker->task);
997 return true;
998 }
999
1000 return false;
1001 }
1002
io_wq_worker_cancel(struct io_worker * worker,void * data)1003 static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
1004 {
1005 struct io_cb_cancel_data *match = data;
1006
1007 /*
1008 * Hold the lock to avoid ->cur_work going out of scope, caller
1009 * may dereference the passed in work.
1010 */
1011 raw_spin_lock(&worker->lock);
1012 if (__io_wq_worker_cancel(worker, match, worker->cur_work) ||
1013 __io_wq_worker_cancel(worker, match, worker->next_work))
1014 match->nr_running++;
1015 raw_spin_unlock(&worker->lock);
1016
1017 return match->nr_running && !match->cancel_all;
1018 }
1019
io_wq_remove_pending(struct io_wq * wq,struct io_wq_work * work,struct io_wq_work_node * prev)1020 static inline void io_wq_remove_pending(struct io_wq *wq,
1021 struct io_wq_work *work,
1022 struct io_wq_work_node *prev)
1023 {
1024 struct io_wq_acct *acct = io_work_get_acct(wq, work);
1025 unsigned int hash = io_get_work_hash(work);
1026 struct io_wq_work *prev_work = NULL;
1027
1028 if (io_wq_is_hashed(work) && work == wq->hash_tail[hash]) {
1029 if (prev)
1030 prev_work = container_of(prev, struct io_wq_work, list);
1031 if (prev_work && io_get_work_hash(prev_work) == hash)
1032 wq->hash_tail[hash] = prev_work;
1033 else
1034 wq->hash_tail[hash] = NULL;
1035 }
1036 wq_list_del(&acct->work_list, &work->list, prev);
1037 }
1038
io_acct_cancel_pending_work(struct io_wq * wq,struct io_wq_acct * acct,struct io_cb_cancel_data * match)1039 static bool io_acct_cancel_pending_work(struct io_wq *wq,
1040 struct io_wq_acct *acct,
1041 struct io_cb_cancel_data *match)
1042 {
1043 struct io_wq_work_node *node, *prev;
1044 struct io_wq_work *work;
1045
1046 raw_spin_lock(&acct->lock);
1047 wq_list_for_each(node, prev, &acct->work_list) {
1048 work = container_of(node, struct io_wq_work, list);
1049 if (!match->fn(work, match->data))
1050 continue;
1051 io_wq_remove_pending(wq, work, prev);
1052 raw_spin_unlock(&acct->lock);
1053 io_run_cancel(work, wq);
1054 match->nr_pending++;
1055 /* not safe to continue after unlock */
1056 return true;
1057 }
1058 raw_spin_unlock(&acct->lock);
1059
1060 return false;
1061 }
1062
io_wq_cancel_pending_work(struct io_wq * wq,struct io_cb_cancel_data * match)1063 static void io_wq_cancel_pending_work(struct io_wq *wq,
1064 struct io_cb_cancel_data *match)
1065 {
1066 int i;
1067 retry:
1068 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1069 struct io_wq_acct *acct = io_get_acct(wq, i == 0);
1070
1071 if (io_acct_cancel_pending_work(wq, acct, match)) {
1072 if (match->cancel_all)
1073 goto retry;
1074 break;
1075 }
1076 }
1077 }
1078
io_wq_cancel_running_work(struct io_wq * wq,struct io_cb_cancel_data * match)1079 static void io_wq_cancel_running_work(struct io_wq *wq,
1080 struct io_cb_cancel_data *match)
1081 {
1082 rcu_read_lock();
1083 io_wq_for_each_worker(wq, io_wq_worker_cancel, match);
1084 rcu_read_unlock();
1085 }
1086
io_wq_cancel_cb(struct io_wq * wq,work_cancel_fn * cancel,void * data,bool cancel_all)1087 enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
1088 void *data, bool cancel_all)
1089 {
1090 struct io_cb_cancel_data match = {
1091 .fn = cancel,
1092 .data = data,
1093 .cancel_all = cancel_all,
1094 };
1095
1096 /*
1097 * First check pending list, if we're lucky we can just remove it
1098 * from there. CANCEL_OK means that the work is returned as-new,
1099 * no completion will be posted for it.
1100 *
1101 * Then check if a free (going busy) or busy worker has the work
1102 * currently running. If we find it there, we'll return CANCEL_RUNNING
1103 * as an indication that we attempt to signal cancellation. The
1104 * completion will run normally in this case.
1105 *
1106 * Do both of these while holding the wq->lock, to ensure that
1107 * we'll find a work item regardless of state.
1108 */
1109 io_wq_cancel_pending_work(wq, &match);
1110 if (match.nr_pending && !match.cancel_all)
1111 return IO_WQ_CANCEL_OK;
1112
1113 raw_spin_lock(&wq->lock);
1114 io_wq_cancel_running_work(wq, &match);
1115 raw_spin_unlock(&wq->lock);
1116 if (match.nr_running && !match.cancel_all)
1117 return IO_WQ_CANCEL_RUNNING;
1118
1119 if (match.nr_running)
1120 return IO_WQ_CANCEL_RUNNING;
1121 if (match.nr_pending)
1122 return IO_WQ_CANCEL_OK;
1123 return IO_WQ_CANCEL_NOTFOUND;
1124 }
1125
io_wq_hash_wake(struct wait_queue_entry * wait,unsigned mode,int sync,void * key)1126 static int io_wq_hash_wake(struct wait_queue_entry *wait, unsigned mode,
1127 int sync, void *key)
1128 {
1129 struct io_wq *wq = container_of(wait, struct io_wq, wait);
1130 int i;
1131
1132 list_del_init(&wait->entry);
1133
1134 rcu_read_lock();
1135 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1136 struct io_wq_acct *acct = &wq->acct[i];
1137
1138 if (test_and_clear_bit(IO_ACCT_STALLED_BIT, &acct->flags))
1139 io_wq_activate_free_worker(wq, acct);
1140 }
1141 rcu_read_unlock();
1142 return 1;
1143 }
1144
io_wq_create(unsigned bounded,struct io_wq_data * data)1145 struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
1146 {
1147 int ret, i;
1148 struct io_wq *wq;
1149
1150 if (WARN_ON_ONCE(!data->free_work || !data->do_work))
1151 return ERR_PTR(-EINVAL);
1152 if (WARN_ON_ONCE(!bounded))
1153 return ERR_PTR(-EINVAL);
1154
1155 wq = kzalloc(sizeof(struct io_wq), GFP_KERNEL);
1156 if (!wq)
1157 return ERR_PTR(-ENOMEM);
1158
1159 refcount_inc(&data->hash->refs);
1160 wq->hash = data->hash;
1161 wq->free_work = data->free_work;
1162 wq->do_work = data->do_work;
1163
1164 ret = -ENOMEM;
1165
1166 if (!alloc_cpumask_var(&wq->cpu_mask, GFP_KERNEL))
1167 goto err;
1168 cpumask_copy(wq->cpu_mask, cpu_possible_mask);
1169 wq->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
1170 wq->acct[IO_WQ_ACCT_UNBOUND].max_workers =
1171 task_rlimit(current, RLIMIT_NPROC);
1172 INIT_LIST_HEAD(&wq->wait.entry);
1173 wq->wait.func = io_wq_hash_wake;
1174 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1175 struct io_wq_acct *acct = &wq->acct[i];
1176
1177 acct->index = i;
1178 atomic_set(&acct->nr_running, 0);
1179 INIT_WQ_LIST(&acct->work_list);
1180 raw_spin_lock_init(&acct->lock);
1181 }
1182
1183 raw_spin_lock_init(&wq->lock);
1184 INIT_HLIST_NULLS_HEAD(&wq->free_list, 0);
1185 INIT_LIST_HEAD(&wq->all_list);
1186
1187 wq->task = get_task_struct(data->task);
1188 atomic_set(&wq->worker_refs, 1);
1189 init_completion(&wq->worker_done);
1190 ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1191 if (ret)
1192 goto err;
1193
1194 return wq;
1195 err:
1196 io_wq_put_hash(data->hash);
1197 free_cpumask_var(wq->cpu_mask);
1198 kfree(wq);
1199 return ERR_PTR(ret);
1200 }
1201
io_task_work_match(struct callback_head * cb,void * data)1202 static bool io_task_work_match(struct callback_head *cb, void *data)
1203 {
1204 struct io_worker *worker;
1205
1206 if (cb->func != create_worker_cb && cb->func != create_worker_cont)
1207 return false;
1208 worker = container_of(cb, struct io_worker, create_work);
1209 return worker->wq == data;
1210 }
1211
io_wq_exit_start(struct io_wq * wq)1212 void io_wq_exit_start(struct io_wq *wq)
1213 {
1214 set_bit(IO_WQ_BIT_EXIT, &wq->state);
1215 }
1216
io_wq_cancel_tw_create(struct io_wq * wq)1217 static void io_wq_cancel_tw_create(struct io_wq *wq)
1218 {
1219 struct callback_head *cb;
1220
1221 while ((cb = task_work_cancel_match(wq->task, io_task_work_match, wq)) != NULL) {
1222 struct io_worker *worker;
1223
1224 worker = container_of(cb, struct io_worker, create_work);
1225 io_worker_cancel_cb(worker);
1226 /*
1227 * Only the worker continuation helper has worker allocated and
1228 * hence needs freeing.
1229 */
1230 if (cb->func == create_worker_cont)
1231 kfree(worker);
1232 }
1233 }
1234
io_wq_exit_workers(struct io_wq * wq)1235 static void io_wq_exit_workers(struct io_wq *wq)
1236 {
1237 if (!wq->task)
1238 return;
1239
1240 io_wq_cancel_tw_create(wq);
1241
1242 rcu_read_lock();
1243 io_wq_for_each_worker(wq, io_wq_worker_wake, NULL);
1244 rcu_read_unlock();
1245 io_worker_ref_put(wq);
1246 wait_for_completion(&wq->worker_done);
1247
1248 spin_lock_irq(&wq->hash->wait.lock);
1249 list_del_init(&wq->wait.entry);
1250 spin_unlock_irq(&wq->hash->wait.lock);
1251
1252 put_task_struct(wq->task);
1253 wq->task = NULL;
1254 }
1255
io_wq_destroy(struct io_wq * wq)1256 static void io_wq_destroy(struct io_wq *wq)
1257 {
1258 struct io_cb_cancel_data match = {
1259 .fn = io_wq_work_match_all,
1260 .cancel_all = true,
1261 };
1262
1263 cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1264 io_wq_cancel_pending_work(wq, &match);
1265 free_cpumask_var(wq->cpu_mask);
1266 io_wq_put_hash(wq->hash);
1267 kfree(wq);
1268 }
1269
io_wq_put_and_exit(struct io_wq * wq)1270 void io_wq_put_and_exit(struct io_wq *wq)
1271 {
1272 WARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, &wq->state));
1273
1274 io_wq_exit_workers(wq);
1275 io_wq_destroy(wq);
1276 }
1277
1278 struct online_data {
1279 unsigned int cpu;
1280 bool online;
1281 };
1282
io_wq_worker_affinity(struct io_worker * worker,void * data)1283 static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
1284 {
1285 struct online_data *od = data;
1286
1287 if (od->online)
1288 cpumask_set_cpu(od->cpu, worker->wq->cpu_mask);
1289 else
1290 cpumask_clear_cpu(od->cpu, worker->wq->cpu_mask);
1291 return false;
1292 }
1293
__io_wq_cpu_online(struct io_wq * wq,unsigned int cpu,bool online)1294 static int __io_wq_cpu_online(struct io_wq *wq, unsigned int cpu, bool online)
1295 {
1296 struct online_data od = {
1297 .cpu = cpu,
1298 .online = online
1299 };
1300
1301 rcu_read_lock();
1302 io_wq_for_each_worker(wq, io_wq_worker_affinity, &od);
1303 rcu_read_unlock();
1304 return 0;
1305 }
1306
io_wq_cpu_online(unsigned int cpu,struct hlist_node * node)1307 static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
1308 {
1309 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1310
1311 return __io_wq_cpu_online(wq, cpu, true);
1312 }
1313
io_wq_cpu_offline(unsigned int cpu,struct hlist_node * node)1314 static int io_wq_cpu_offline(unsigned int cpu, struct hlist_node *node)
1315 {
1316 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1317
1318 return __io_wq_cpu_online(wq, cpu, false);
1319 }
1320
io_wq_cpu_affinity(struct io_uring_task * tctx,cpumask_var_t mask)1321 int io_wq_cpu_affinity(struct io_uring_task *tctx, cpumask_var_t mask)
1322 {
1323 if (!tctx || !tctx->io_wq)
1324 return -EINVAL;
1325
1326 rcu_read_lock();
1327 if (mask)
1328 cpumask_copy(tctx->io_wq->cpu_mask, mask);
1329 else
1330 cpumask_copy(tctx->io_wq->cpu_mask, cpu_possible_mask);
1331 rcu_read_unlock();
1332
1333 return 0;
1334 }
1335
1336 /*
1337 * Set max number of unbounded workers, returns old value. If new_count is 0,
1338 * then just return the old value.
1339 */
io_wq_max_workers(struct io_wq * wq,int * new_count)1340 int io_wq_max_workers(struct io_wq *wq, int *new_count)
1341 {
1342 struct io_wq_acct *acct;
1343 int prev[IO_WQ_ACCT_NR];
1344 int i;
1345
1346 BUILD_BUG_ON((int) IO_WQ_ACCT_BOUND != (int) IO_WQ_BOUND);
1347 BUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND);
1348 BUILD_BUG_ON((int) IO_WQ_ACCT_NR != 2);
1349
1350 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1351 if (new_count[i] > task_rlimit(current, RLIMIT_NPROC))
1352 new_count[i] = task_rlimit(current, RLIMIT_NPROC);
1353 }
1354
1355 for (i = 0; i < IO_WQ_ACCT_NR; i++)
1356 prev[i] = 0;
1357
1358 rcu_read_lock();
1359
1360 raw_spin_lock(&wq->lock);
1361 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1362 acct = &wq->acct[i];
1363 prev[i] = max_t(int, acct->max_workers, prev[i]);
1364 if (new_count[i])
1365 acct->max_workers = new_count[i];
1366 }
1367 raw_spin_unlock(&wq->lock);
1368 rcu_read_unlock();
1369
1370 for (i = 0; i < IO_WQ_ACCT_NR; i++)
1371 new_count[i] = prev[i];
1372
1373 return 0;
1374 }
1375
io_wq_init(void)1376 static __init int io_wq_init(void)
1377 {
1378 int ret;
1379
1380 ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "io-wq/online",
1381 io_wq_cpu_online, io_wq_cpu_offline);
1382 if (ret < 0)
1383 return ret;
1384 io_wq_online = ret;
1385 return 0;
1386 }
1387 subsys_initcall(io_wq_init);
1388