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/cpuset.h>
17 #include <linux/task_work.h>
18 #include <linux/audit.h>
19 #include <linux/mmu_context.h>
20 #include <uapi/linux/io_uring.h>
21
22 #include "io-wq.h"
23 #include "slist.h"
24 #include "io_uring.h"
25
26 #define WORKER_IDLE_TIMEOUT (5 * HZ)
27 #define WORKER_INIT_LIMIT 3
28
29 enum {
30 IO_WORKER_F_UP = 0, /* up and active */
31 IO_WORKER_F_RUNNING = 1, /* account as running */
32 IO_WORKER_F_FREE = 2, /* worker on free list */
33 IO_WORKER_F_BOUND = 3, /* is doing bounded work */
34 };
35
36 enum {
37 IO_WQ_BIT_EXIT = 0, /* wq exiting */
38 };
39
40 enum {
41 IO_ACCT_STALLED_BIT = 0, /* stalled on hash */
42 };
43
44 /*
45 * One for each thread in a wq pool
46 */
47 struct io_worker {
48 refcount_t ref;
49 int create_index;
50 unsigned long flags;
51 struct hlist_nulls_node nulls_node;
52 struct list_head all_list;
53 struct task_struct *task;
54 struct io_wq *wq;
55
56 struct io_wq_work *cur_work;
57 raw_spinlock_t lock;
58
59 struct completion ref_done;
60
61 unsigned long create_state;
62 struct callback_head create_work;
63 int init_retries;
64
65 union {
66 struct rcu_head rcu;
67 struct delayed_work work;
68 };
69 };
70
71 #if BITS_PER_LONG == 64
72 #define IO_WQ_HASH_ORDER 6
73 #else
74 #define IO_WQ_HASH_ORDER 5
75 #endif
76
77 #define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
78
79 struct io_wq_acct {
80 unsigned nr_workers;
81 unsigned max_workers;
82 int index;
83 atomic_t nr_running;
84 raw_spinlock_t lock;
85 struct io_wq_work_list work_list;
86 unsigned long flags;
87 };
88
89 enum {
90 IO_WQ_ACCT_BOUND,
91 IO_WQ_ACCT_UNBOUND,
92 IO_WQ_ACCT_NR,
93 };
94
95 /*
96 * Per io_wq state
97 */
98 struct io_wq {
99 unsigned long state;
100
101 free_work_fn *free_work;
102 io_wq_work_fn *do_work;
103
104 struct io_wq_hash *hash;
105
106 atomic_t worker_refs;
107 struct completion worker_done;
108
109 struct hlist_node cpuhp_node;
110
111 struct task_struct *task;
112
113 struct io_wq_acct acct[IO_WQ_ACCT_NR];
114
115 /* lock protects access to elements below */
116 raw_spinlock_t lock;
117
118 struct hlist_nulls_head free_list;
119 struct list_head all_list;
120
121 struct wait_queue_entry wait;
122
123 struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
124
125 cpumask_var_t cpu_mask;
126 };
127
128 static enum cpuhp_state io_wq_online;
129
130 struct io_cb_cancel_data {
131 work_cancel_fn *fn;
132 void *data;
133 int nr_running;
134 int nr_pending;
135 bool cancel_all;
136 };
137
138 static bool create_io_worker(struct io_wq *wq, int index);
139 static void io_wq_dec_running(struct io_worker *worker);
140 static bool io_acct_cancel_pending_work(struct io_wq *wq,
141 struct io_wq_acct *acct,
142 struct io_cb_cancel_data *match);
143 static void create_worker_cb(struct callback_head *cb);
144 static void io_wq_cancel_tw_create(struct io_wq *wq);
145
io_worker_get(struct io_worker * worker)146 static bool io_worker_get(struct io_worker *worker)
147 {
148 return refcount_inc_not_zero(&worker->ref);
149 }
150
io_worker_release(struct io_worker * worker)151 static void io_worker_release(struct io_worker *worker)
152 {
153 if (refcount_dec_and_test(&worker->ref))
154 complete(&worker->ref_done);
155 }
156
io_get_acct(struct io_wq * wq,bool bound)157 static inline struct io_wq_acct *io_get_acct(struct io_wq *wq, bool bound)
158 {
159 return &wq->acct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND];
160 }
161
io_work_get_acct(struct io_wq * wq,struct io_wq_work * work)162 static inline struct io_wq_acct *io_work_get_acct(struct io_wq *wq,
163 struct io_wq_work *work)
164 {
165 return io_get_acct(wq, !(atomic_read(&work->flags) & IO_WQ_WORK_UNBOUND));
166 }
167
io_wq_get_acct(struct io_worker * worker)168 static inline struct io_wq_acct *io_wq_get_acct(struct io_worker *worker)
169 {
170 return io_get_acct(worker->wq, test_bit(IO_WORKER_F_BOUND, &worker->flags));
171 }
172
io_worker_ref_put(struct io_wq * wq)173 static void io_worker_ref_put(struct io_wq *wq)
174 {
175 if (atomic_dec_and_test(&wq->worker_refs))
176 complete(&wq->worker_done);
177 }
178
io_wq_worker_stopped(void)179 bool io_wq_worker_stopped(void)
180 {
181 struct io_worker *worker = current->worker_private;
182
183 if (WARN_ON_ONCE(!io_wq_current_is_worker()))
184 return true;
185
186 return test_bit(IO_WQ_BIT_EXIT, &worker->wq->state);
187 }
188
io_worker_cancel_cb(struct io_worker * worker)189 static void io_worker_cancel_cb(struct io_worker *worker)
190 {
191 struct io_wq_acct *acct = io_wq_get_acct(worker);
192 struct io_wq *wq = worker->wq;
193
194 atomic_dec(&acct->nr_running);
195 raw_spin_lock(&wq->lock);
196 acct->nr_workers--;
197 raw_spin_unlock(&wq->lock);
198 io_worker_ref_put(wq);
199 clear_bit_unlock(0, &worker->create_state);
200 io_worker_release(worker);
201 }
202
io_task_worker_match(struct callback_head * cb,void * data)203 static bool io_task_worker_match(struct callback_head *cb, void *data)
204 {
205 struct io_worker *worker;
206
207 if (cb->func != create_worker_cb)
208 return false;
209 worker = container_of(cb, struct io_worker, create_work);
210 return worker == data;
211 }
212
io_worker_exit(struct io_worker * worker)213 static void io_worker_exit(struct io_worker *worker)
214 {
215 struct io_wq *wq = worker->wq;
216
217 while (1) {
218 struct callback_head *cb = task_work_cancel_match(wq->task,
219 io_task_worker_match, worker);
220
221 if (!cb)
222 break;
223 io_worker_cancel_cb(worker);
224 }
225
226 io_worker_release(worker);
227 wait_for_completion(&worker->ref_done);
228
229 raw_spin_lock(&wq->lock);
230 if (test_bit(IO_WORKER_F_FREE, &worker->flags))
231 hlist_nulls_del_rcu(&worker->nulls_node);
232 list_del_rcu(&worker->all_list);
233 raw_spin_unlock(&wq->lock);
234 io_wq_dec_running(worker);
235 /*
236 * this worker is a goner, clear ->worker_private to avoid any
237 * inc/dec running calls that could happen as part of exit from
238 * touching 'worker'.
239 */
240 current->worker_private = NULL;
241
242 kfree_rcu(worker, rcu);
243 io_worker_ref_put(wq);
244 do_exit(0);
245 }
246
__io_acct_run_queue(struct io_wq_acct * acct)247 static inline bool __io_acct_run_queue(struct io_wq_acct *acct)
248 {
249 return !test_bit(IO_ACCT_STALLED_BIT, &acct->flags) &&
250 !wq_list_empty(&acct->work_list);
251 }
252
253 /*
254 * If there's work to do, returns true with acct->lock acquired. If not,
255 * returns false with no lock held.
256 */
io_acct_run_queue(struct io_wq_acct * acct)257 static inline bool io_acct_run_queue(struct io_wq_acct *acct)
258 __acquires(&acct->lock)
259 {
260 raw_spin_lock(&acct->lock);
261 if (__io_acct_run_queue(acct))
262 return true;
263
264 raw_spin_unlock(&acct->lock);
265 return false;
266 }
267
268 /*
269 * Check head of free list for an available worker. If one isn't available,
270 * caller must create one.
271 */
io_wq_activate_free_worker(struct io_wq * wq,struct io_wq_acct * acct)272 static bool io_wq_activate_free_worker(struct io_wq *wq,
273 struct io_wq_acct *acct)
274 __must_hold(RCU)
275 {
276 struct hlist_nulls_node *n;
277 struct io_worker *worker;
278
279 /*
280 * Iterate free_list and see if we can find an idle worker to
281 * activate. If a given worker is on the free_list but in the process
282 * of exiting, keep trying.
283 */
284 hlist_nulls_for_each_entry_rcu(worker, n, &wq->free_list, nulls_node) {
285 if (!io_worker_get(worker))
286 continue;
287 if (io_wq_get_acct(worker) != acct) {
288 io_worker_release(worker);
289 continue;
290 }
291 /*
292 * If the worker is already running, it's either already
293 * starting work or finishing work. In either case, if it does
294 * to go sleep, we'll kick off a new task for this work anyway.
295 */
296 wake_up_process(worker->task);
297 io_worker_release(worker);
298 return true;
299 }
300
301 return false;
302 }
303
304 /*
305 * We need a worker. If we find a free one, we're good. If not, and we're
306 * below the max number of workers, create one.
307 */
io_wq_create_worker(struct io_wq * wq,struct io_wq_acct * acct)308 static bool io_wq_create_worker(struct io_wq *wq, struct io_wq_acct *acct)
309 {
310 /*
311 * Most likely an attempt to queue unbounded work on an io_wq that
312 * wasn't setup with any unbounded workers.
313 */
314 if (unlikely(!acct->max_workers))
315 pr_warn_once("io-wq is not configured for unbound workers");
316
317 raw_spin_lock(&wq->lock);
318 if (acct->nr_workers >= acct->max_workers) {
319 raw_spin_unlock(&wq->lock);
320 return true;
321 }
322 acct->nr_workers++;
323 raw_spin_unlock(&wq->lock);
324 atomic_inc(&acct->nr_running);
325 atomic_inc(&wq->worker_refs);
326 return create_io_worker(wq, acct->index);
327 }
328
io_wq_inc_running(struct io_worker * worker)329 static void io_wq_inc_running(struct io_worker *worker)
330 {
331 struct io_wq_acct *acct = io_wq_get_acct(worker);
332
333 atomic_inc(&acct->nr_running);
334 }
335
create_worker_cb(struct callback_head * cb)336 static void create_worker_cb(struct callback_head *cb)
337 {
338 struct io_worker *worker;
339 struct io_wq *wq;
340
341 struct io_wq_acct *acct;
342 bool do_create = false;
343
344 worker = container_of(cb, struct io_worker, create_work);
345 wq = worker->wq;
346 acct = &wq->acct[worker->create_index];
347 raw_spin_lock(&wq->lock);
348
349 if (acct->nr_workers < acct->max_workers) {
350 acct->nr_workers++;
351 do_create = true;
352 }
353 raw_spin_unlock(&wq->lock);
354 if (do_create) {
355 create_io_worker(wq, worker->create_index);
356 } else {
357 atomic_dec(&acct->nr_running);
358 io_worker_ref_put(wq);
359 }
360 clear_bit_unlock(0, &worker->create_state);
361 io_worker_release(worker);
362 }
363
io_queue_worker_create(struct io_worker * worker,struct io_wq_acct * acct,task_work_func_t func)364 static bool io_queue_worker_create(struct io_worker *worker,
365 struct io_wq_acct *acct,
366 task_work_func_t func)
367 {
368 struct io_wq *wq = worker->wq;
369
370 /* raced with exit, just ignore create call */
371 if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
372 goto fail;
373 if (!io_worker_get(worker))
374 goto fail;
375 /*
376 * create_state manages ownership of create_work/index. We should
377 * only need one entry per worker, as the worker going to sleep
378 * will trigger the condition, and waking will clear it once it
379 * runs the task_work.
380 */
381 if (test_bit(0, &worker->create_state) ||
382 test_and_set_bit_lock(0, &worker->create_state))
383 goto fail_release;
384
385 atomic_inc(&wq->worker_refs);
386 init_task_work(&worker->create_work, func);
387 worker->create_index = acct->index;
388 if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
389 /*
390 * EXIT may have been set after checking it above, check after
391 * adding the task_work and remove any creation item if it is
392 * now set. wq exit does that too, but we can have added this
393 * work item after we canceled in io_wq_exit_workers().
394 */
395 if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
396 io_wq_cancel_tw_create(wq);
397 io_worker_ref_put(wq);
398 return true;
399 }
400 io_worker_ref_put(wq);
401 clear_bit_unlock(0, &worker->create_state);
402 fail_release:
403 io_worker_release(worker);
404 fail:
405 atomic_dec(&acct->nr_running);
406 io_worker_ref_put(wq);
407 return false;
408 }
409
io_wq_dec_running(struct io_worker * worker)410 static void io_wq_dec_running(struct io_worker *worker)
411 {
412 struct io_wq_acct *acct = io_wq_get_acct(worker);
413 struct io_wq *wq = worker->wq;
414
415 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
416 return;
417
418 if (!atomic_dec_and_test(&acct->nr_running))
419 return;
420 if (!io_acct_run_queue(acct))
421 return;
422
423 raw_spin_unlock(&acct->lock);
424 atomic_inc(&acct->nr_running);
425 atomic_inc(&wq->worker_refs);
426 io_queue_worker_create(worker, acct, create_worker_cb);
427 }
428
429 /*
430 * Worker will start processing some work. Move it to the busy list, if
431 * it's currently on the freelist
432 */
__io_worker_busy(struct io_wq * wq,struct io_worker * worker)433 static void __io_worker_busy(struct io_wq *wq, struct io_worker *worker)
434 {
435 if (test_bit(IO_WORKER_F_FREE, &worker->flags)) {
436 clear_bit(IO_WORKER_F_FREE, &worker->flags);
437 raw_spin_lock(&wq->lock);
438 hlist_nulls_del_init_rcu(&worker->nulls_node);
439 raw_spin_unlock(&wq->lock);
440 }
441 }
442
443 /*
444 * No work, worker going to sleep. Move to freelist.
445 */
__io_worker_idle(struct io_wq * wq,struct io_worker * worker)446 static void __io_worker_idle(struct io_wq *wq, struct io_worker *worker)
447 __must_hold(wq->lock)
448 {
449 if (!test_bit(IO_WORKER_F_FREE, &worker->flags)) {
450 set_bit(IO_WORKER_F_FREE, &worker->flags);
451 hlist_nulls_add_head_rcu(&worker->nulls_node, &wq->free_list);
452 }
453 }
454
io_get_work_hash(struct io_wq_work * work)455 static inline unsigned int io_get_work_hash(struct io_wq_work *work)
456 {
457 return atomic_read(&work->flags) >> IO_WQ_HASH_SHIFT;
458 }
459
io_wait_on_hash(struct io_wq * wq,unsigned int hash)460 static bool io_wait_on_hash(struct io_wq *wq, unsigned int hash)
461 {
462 bool ret = false;
463
464 spin_lock_irq(&wq->hash->wait.lock);
465 if (list_empty(&wq->wait.entry)) {
466 __add_wait_queue(&wq->hash->wait, &wq->wait);
467 if (!test_bit(hash, &wq->hash->map)) {
468 __set_current_state(TASK_RUNNING);
469 list_del_init(&wq->wait.entry);
470 ret = true;
471 }
472 }
473 spin_unlock_irq(&wq->hash->wait.lock);
474 return ret;
475 }
476
io_get_next_work(struct io_wq_acct * acct,struct io_worker * worker)477 static struct io_wq_work *io_get_next_work(struct io_wq_acct *acct,
478 struct io_worker *worker)
479 __must_hold(acct->lock)
480 {
481 struct io_wq_work_node *node, *prev;
482 struct io_wq_work *work, *tail;
483 unsigned int stall_hash = -1U;
484 struct io_wq *wq = worker->wq;
485
486 wq_list_for_each(node, prev, &acct->work_list) {
487 unsigned int hash;
488
489 work = container_of(node, struct io_wq_work, list);
490
491 /* not hashed, can run anytime */
492 if (!io_wq_is_hashed(work)) {
493 wq_list_del(&acct->work_list, node, prev);
494 return work;
495 }
496
497 hash = io_get_work_hash(work);
498 /* all items with this hash lie in [work, tail] */
499 tail = wq->hash_tail[hash];
500
501 /* hashed, can run if not already running */
502 if (!test_and_set_bit(hash, &wq->hash->map)) {
503 wq->hash_tail[hash] = NULL;
504 wq_list_cut(&acct->work_list, &tail->list, prev);
505 return work;
506 }
507 if (stall_hash == -1U)
508 stall_hash = hash;
509 /* fast forward to a next hash, for-each will fix up @prev */
510 node = &tail->list;
511 }
512
513 if (stall_hash != -1U) {
514 bool unstalled;
515
516 /*
517 * Set this before dropping the lock to avoid racing with new
518 * work being added and clearing the stalled bit.
519 */
520 set_bit(IO_ACCT_STALLED_BIT, &acct->flags);
521 raw_spin_unlock(&acct->lock);
522 unstalled = io_wait_on_hash(wq, stall_hash);
523 raw_spin_lock(&acct->lock);
524 if (unstalled) {
525 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
526 if (wq_has_sleeper(&wq->hash->wait))
527 wake_up(&wq->hash->wait);
528 }
529 }
530
531 return NULL;
532 }
533
io_assign_current_work(struct io_worker * worker,struct io_wq_work * work)534 static void io_assign_current_work(struct io_worker *worker,
535 struct io_wq_work *work)
536 {
537 if (work) {
538 io_run_task_work();
539 cond_resched();
540 }
541
542 raw_spin_lock(&worker->lock);
543 worker->cur_work = work;
544 raw_spin_unlock(&worker->lock);
545 }
546
547 /*
548 * Called with acct->lock held, drops it before returning
549 */
io_worker_handle_work(struct io_wq_acct * acct,struct io_worker * worker)550 static void io_worker_handle_work(struct io_wq_acct *acct,
551 struct io_worker *worker)
552 __releases(&acct->lock)
553 {
554 struct io_wq *wq = worker->wq;
555 bool do_kill = test_bit(IO_WQ_BIT_EXIT, &wq->state);
556
557 do {
558 struct io_wq_work *work;
559
560 /*
561 * If we got some work, mark us as busy. If we didn't, but
562 * the list isn't empty, it means we stalled on hashed work.
563 * Mark us stalled so we don't keep looking for work when we
564 * can't make progress, any work completion or insertion will
565 * clear the stalled flag.
566 */
567 work = io_get_next_work(acct, worker);
568 if (work) {
569 /*
570 * Make sure cancelation can find this, even before
571 * it becomes the active work. That avoids a window
572 * where the work has been removed from our general
573 * work list, but isn't yet discoverable as the
574 * current work item for this worker.
575 */
576 raw_spin_lock(&worker->lock);
577 worker->cur_work = work;
578 raw_spin_unlock(&worker->lock);
579 }
580
581 raw_spin_unlock(&acct->lock);
582
583 if (!work)
584 break;
585
586 __io_worker_busy(wq, worker);
587
588 io_assign_current_work(worker, work);
589 __set_current_state(TASK_RUNNING);
590
591 /* handle a whole dependent link */
592 do {
593 struct io_wq_work *next_hashed, *linked;
594 unsigned int hash = io_get_work_hash(work);
595
596 next_hashed = wq_next_work(work);
597
598 if (do_kill &&
599 (atomic_read(&work->flags) & IO_WQ_WORK_UNBOUND))
600 atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
601 wq->do_work(work);
602 io_assign_current_work(worker, NULL);
603
604 linked = wq->free_work(work);
605 work = next_hashed;
606 if (!work && linked && !io_wq_is_hashed(linked)) {
607 work = linked;
608 linked = NULL;
609 }
610 io_assign_current_work(worker, work);
611 if (linked)
612 io_wq_enqueue(wq, linked);
613
614 if (hash != -1U && !next_hashed) {
615 /* serialize hash clear with wake_up() */
616 spin_lock_irq(&wq->hash->wait.lock);
617 clear_bit(hash, &wq->hash->map);
618 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
619 spin_unlock_irq(&wq->hash->wait.lock);
620 if (wq_has_sleeper(&wq->hash->wait))
621 wake_up(&wq->hash->wait);
622 }
623 } while (work);
624
625 if (!__io_acct_run_queue(acct))
626 break;
627 raw_spin_lock(&acct->lock);
628 } while (1);
629 }
630
io_wq_worker(void * data)631 static int io_wq_worker(void *data)
632 {
633 struct io_worker *worker = data;
634 struct io_wq_acct *acct = io_wq_get_acct(worker);
635 struct io_wq *wq = worker->wq;
636 bool exit_mask = false, last_timeout = false;
637 char buf[TASK_COMM_LEN] = {};
638
639 set_mask_bits(&worker->flags, 0,
640 BIT(IO_WORKER_F_UP) | BIT(IO_WORKER_F_RUNNING));
641
642 snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid);
643 set_task_comm(current, buf);
644
645 while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
646 long ret;
647
648 set_current_state(TASK_INTERRUPTIBLE);
649
650 /*
651 * If we have work to do, io_acct_run_queue() returns with
652 * the acct->lock held. If not, it will drop it.
653 */
654 while (io_acct_run_queue(acct))
655 io_worker_handle_work(acct, worker);
656
657 raw_spin_lock(&wq->lock);
658 /*
659 * Last sleep timed out. Exit if we're not the last worker,
660 * or if someone modified our affinity.
661 */
662 if (last_timeout && (exit_mask || acct->nr_workers > 1)) {
663 acct->nr_workers--;
664 raw_spin_unlock(&wq->lock);
665 __set_current_state(TASK_RUNNING);
666 break;
667 }
668 last_timeout = false;
669 __io_worker_idle(wq, worker);
670 raw_spin_unlock(&wq->lock);
671 if (io_run_task_work())
672 continue;
673 ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
674 if (signal_pending(current)) {
675 struct ksignal ksig;
676
677 if (!get_signal(&ksig))
678 continue;
679 break;
680 }
681 if (!ret) {
682 last_timeout = true;
683 exit_mask = !cpumask_test_cpu(raw_smp_processor_id(),
684 wq->cpu_mask);
685 }
686 }
687
688 if (test_bit(IO_WQ_BIT_EXIT, &wq->state) && io_acct_run_queue(acct))
689 io_worker_handle_work(acct, worker);
690
691 io_worker_exit(worker);
692 return 0;
693 }
694
695 /*
696 * Called when a worker is scheduled in. Mark us as currently running.
697 */
io_wq_worker_running(struct task_struct * tsk)698 void io_wq_worker_running(struct task_struct *tsk)
699 {
700 struct io_worker *worker = tsk->worker_private;
701
702 if (!worker)
703 return;
704 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
705 return;
706 if (test_bit(IO_WORKER_F_RUNNING, &worker->flags))
707 return;
708 set_bit(IO_WORKER_F_RUNNING, &worker->flags);
709 io_wq_inc_running(worker);
710 }
711
712 /*
713 * Called when worker is going to sleep. If there are no workers currently
714 * running and we have work pending, wake up a free one or create a new one.
715 */
io_wq_worker_sleeping(struct task_struct * tsk)716 void io_wq_worker_sleeping(struct task_struct *tsk)
717 {
718 struct io_worker *worker = tsk->worker_private;
719
720 if (!worker)
721 return;
722 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
723 return;
724 if (!test_bit(IO_WORKER_F_RUNNING, &worker->flags))
725 return;
726
727 clear_bit(IO_WORKER_F_RUNNING, &worker->flags);
728 io_wq_dec_running(worker);
729 }
730
io_init_new_worker(struct io_wq * wq,struct io_worker * worker,struct task_struct * tsk)731 static void io_init_new_worker(struct io_wq *wq, struct io_worker *worker,
732 struct task_struct *tsk)
733 {
734 tsk->worker_private = worker;
735 worker->task = tsk;
736 set_cpus_allowed_ptr(tsk, wq->cpu_mask);
737
738 raw_spin_lock(&wq->lock);
739 hlist_nulls_add_head_rcu(&worker->nulls_node, &wq->free_list);
740 list_add_tail_rcu(&worker->all_list, &wq->all_list);
741 set_bit(IO_WORKER_F_FREE, &worker->flags);
742 raw_spin_unlock(&wq->lock);
743 wake_up_new_task(tsk);
744 }
745
io_wq_work_match_all(struct io_wq_work * work,void * data)746 static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
747 {
748 return true;
749 }
750
io_should_retry_thread(struct io_worker * worker,long err)751 static inline bool io_should_retry_thread(struct io_worker *worker, long err)
752 {
753 /*
754 * Prevent perpetual task_work retry, if the task (or its group) is
755 * exiting.
756 */
757 if (fatal_signal_pending(current))
758 return false;
759 if (worker->init_retries++ >= WORKER_INIT_LIMIT)
760 return false;
761
762 switch (err) {
763 case -EAGAIN:
764 case -ERESTARTSYS:
765 case -ERESTARTNOINTR:
766 case -ERESTARTNOHAND:
767 return true;
768 default:
769 return false;
770 }
771 }
772
queue_create_worker_retry(struct io_worker * worker)773 static void queue_create_worker_retry(struct io_worker *worker)
774 {
775 /*
776 * We only bother retrying because there's a chance that the
777 * failure to create a worker is due to some temporary condition
778 * in the forking task (e.g. outstanding signal); give the task
779 * some time to clear that condition.
780 */
781 schedule_delayed_work(&worker->work,
782 msecs_to_jiffies(worker->init_retries * 5));
783 }
784
create_worker_cont(struct callback_head * cb)785 static void create_worker_cont(struct callback_head *cb)
786 {
787 struct io_worker *worker;
788 struct task_struct *tsk;
789 struct io_wq *wq;
790
791 worker = container_of(cb, struct io_worker, create_work);
792 clear_bit_unlock(0, &worker->create_state);
793 wq = worker->wq;
794 tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE);
795 if (!IS_ERR(tsk)) {
796 io_init_new_worker(wq, worker, tsk);
797 io_worker_release(worker);
798 return;
799 } else if (!io_should_retry_thread(worker, PTR_ERR(tsk))) {
800 struct io_wq_acct *acct = io_wq_get_acct(worker);
801
802 atomic_dec(&acct->nr_running);
803 raw_spin_lock(&wq->lock);
804 acct->nr_workers--;
805 if (!acct->nr_workers) {
806 struct io_cb_cancel_data match = {
807 .fn = io_wq_work_match_all,
808 .cancel_all = true,
809 };
810
811 raw_spin_unlock(&wq->lock);
812 while (io_acct_cancel_pending_work(wq, acct, &match))
813 ;
814 } else {
815 raw_spin_unlock(&wq->lock);
816 }
817 io_worker_ref_put(wq);
818 kfree(worker);
819 return;
820 }
821
822 /* re-create attempts grab a new worker ref, drop the existing one */
823 io_worker_release(worker);
824 queue_create_worker_retry(worker);
825 }
826
io_workqueue_create(struct work_struct * work)827 static void io_workqueue_create(struct work_struct *work)
828 {
829 struct io_worker *worker = container_of(work, struct io_worker,
830 work.work);
831 struct io_wq_acct *acct = io_wq_get_acct(worker);
832
833 if (!io_queue_worker_create(worker, acct, create_worker_cont))
834 kfree(worker);
835 }
836
create_io_worker(struct io_wq * wq,int index)837 static bool create_io_worker(struct io_wq *wq, int index)
838 {
839 struct io_wq_acct *acct = &wq->acct[index];
840 struct io_worker *worker;
841 struct task_struct *tsk;
842
843 __set_current_state(TASK_RUNNING);
844
845 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
846 if (!worker) {
847 fail:
848 atomic_dec(&acct->nr_running);
849 raw_spin_lock(&wq->lock);
850 acct->nr_workers--;
851 raw_spin_unlock(&wq->lock);
852 io_worker_ref_put(wq);
853 return false;
854 }
855
856 refcount_set(&worker->ref, 1);
857 worker->wq = wq;
858 raw_spin_lock_init(&worker->lock);
859 init_completion(&worker->ref_done);
860
861 if (index == IO_WQ_ACCT_BOUND)
862 set_bit(IO_WORKER_F_BOUND, &worker->flags);
863
864 tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE);
865 if (!IS_ERR(tsk)) {
866 io_init_new_worker(wq, worker, tsk);
867 } else if (!io_should_retry_thread(worker, PTR_ERR(tsk))) {
868 kfree(worker);
869 goto fail;
870 } else {
871 INIT_DELAYED_WORK(&worker->work, io_workqueue_create);
872 queue_create_worker_retry(worker);
873 }
874
875 return true;
876 }
877
878 /*
879 * Iterate the passed in list and call the specific function for each
880 * worker that isn't exiting
881 */
io_wq_for_each_worker(struct io_wq * wq,bool (* func)(struct io_worker *,void *),void * data)882 static bool io_wq_for_each_worker(struct io_wq *wq,
883 bool (*func)(struct io_worker *, void *),
884 void *data)
885 {
886 struct io_worker *worker;
887 bool ret = false;
888
889 list_for_each_entry_rcu(worker, &wq->all_list, all_list) {
890 if (io_worker_get(worker)) {
891 /* no task if node is/was offline */
892 if (worker->task)
893 ret = func(worker, data);
894 io_worker_release(worker);
895 if (ret)
896 break;
897 }
898 }
899
900 return ret;
901 }
902
io_wq_worker_wake(struct io_worker * worker,void * data)903 static bool io_wq_worker_wake(struct io_worker *worker, void *data)
904 {
905 __set_notify_signal(worker->task);
906 wake_up_process(worker->task);
907 return false;
908 }
909
io_run_cancel(struct io_wq_work * work,struct io_wq * wq)910 static void io_run_cancel(struct io_wq_work *work, struct io_wq *wq)
911 {
912 do {
913 atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
914 wq->do_work(work);
915 work = wq->free_work(work);
916 } while (work);
917 }
918
io_wq_insert_work(struct io_wq * wq,struct io_wq_work * work)919 static void io_wq_insert_work(struct io_wq *wq, struct io_wq_work *work)
920 {
921 struct io_wq_acct *acct = io_work_get_acct(wq, work);
922 unsigned int hash;
923 struct io_wq_work *tail;
924
925 if (!io_wq_is_hashed(work)) {
926 append:
927 wq_list_add_tail(&work->list, &acct->work_list);
928 return;
929 }
930
931 hash = io_get_work_hash(work);
932 tail = wq->hash_tail[hash];
933 wq->hash_tail[hash] = work;
934 if (!tail)
935 goto append;
936
937 wq_list_add_after(&work->list, &tail->list, &acct->work_list);
938 }
939
io_wq_work_match_item(struct io_wq_work * work,void * data)940 static bool io_wq_work_match_item(struct io_wq_work *work, void *data)
941 {
942 return work == data;
943 }
944
io_wq_enqueue(struct io_wq * wq,struct io_wq_work * work)945 void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
946 {
947 struct io_wq_acct *acct = io_work_get_acct(wq, work);
948 unsigned int work_flags = atomic_read(&work->flags);
949 struct io_cb_cancel_data match = {
950 .fn = io_wq_work_match_item,
951 .data = work,
952 .cancel_all = false,
953 };
954 bool do_create;
955
956 /*
957 * If io-wq is exiting for this task, or if the request has explicitly
958 * been marked as one that should not get executed, cancel it here.
959 */
960 if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
961 (work_flags & IO_WQ_WORK_CANCEL)) {
962 io_run_cancel(work, wq);
963 return;
964 }
965
966 raw_spin_lock(&acct->lock);
967 io_wq_insert_work(wq, work);
968 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
969 raw_spin_unlock(&acct->lock);
970
971 rcu_read_lock();
972 do_create = !io_wq_activate_free_worker(wq, acct);
973 rcu_read_unlock();
974
975 if (do_create && ((work_flags & IO_WQ_WORK_CONCURRENT) ||
976 !atomic_read(&acct->nr_running))) {
977 bool did_create;
978
979 did_create = io_wq_create_worker(wq, acct);
980 if (likely(did_create))
981 return;
982
983 raw_spin_lock(&wq->lock);
984 if (acct->nr_workers) {
985 raw_spin_unlock(&wq->lock);
986 return;
987 }
988 raw_spin_unlock(&wq->lock);
989
990 /* fatal condition, failed to create the first worker */
991 io_acct_cancel_pending_work(wq, acct, &match);
992 }
993 }
994
995 /*
996 * Work items that hash to the same value will not be done in parallel.
997 * Used to limit concurrent writes, generally hashed by inode.
998 */
io_wq_hash_work(struct io_wq_work * work,void * val)999 void io_wq_hash_work(struct io_wq_work *work, void *val)
1000 {
1001 unsigned int bit;
1002
1003 bit = hash_ptr(val, IO_WQ_HASH_ORDER);
1004 atomic_or(IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT), &work->flags);
1005 }
1006
__io_wq_worker_cancel(struct io_worker * worker,struct io_cb_cancel_data * match,struct io_wq_work * work)1007 static bool __io_wq_worker_cancel(struct io_worker *worker,
1008 struct io_cb_cancel_data *match,
1009 struct io_wq_work *work)
1010 {
1011 if (work && match->fn(work, match->data)) {
1012 atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
1013 __set_notify_signal(worker->task);
1014 return true;
1015 }
1016
1017 return false;
1018 }
1019
io_wq_worker_cancel(struct io_worker * worker,void * data)1020 static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
1021 {
1022 struct io_cb_cancel_data *match = data;
1023
1024 /*
1025 * Hold the lock to avoid ->cur_work going out of scope, caller
1026 * may dereference the passed in work.
1027 */
1028 raw_spin_lock(&worker->lock);
1029 if (__io_wq_worker_cancel(worker, match, worker->cur_work))
1030 match->nr_running++;
1031 raw_spin_unlock(&worker->lock);
1032
1033 return match->nr_running && !match->cancel_all;
1034 }
1035
io_wq_remove_pending(struct io_wq * wq,struct io_wq_work * work,struct io_wq_work_node * prev)1036 static inline void io_wq_remove_pending(struct io_wq *wq,
1037 struct io_wq_work *work,
1038 struct io_wq_work_node *prev)
1039 {
1040 struct io_wq_acct *acct = io_work_get_acct(wq, work);
1041 unsigned int hash = io_get_work_hash(work);
1042 struct io_wq_work *prev_work = NULL;
1043
1044 if (io_wq_is_hashed(work) && work == wq->hash_tail[hash]) {
1045 if (prev)
1046 prev_work = container_of(prev, struct io_wq_work, list);
1047 if (prev_work && io_get_work_hash(prev_work) == hash)
1048 wq->hash_tail[hash] = prev_work;
1049 else
1050 wq->hash_tail[hash] = NULL;
1051 }
1052 wq_list_del(&acct->work_list, &work->list, prev);
1053 }
1054
io_acct_cancel_pending_work(struct io_wq * wq,struct io_wq_acct * acct,struct io_cb_cancel_data * match)1055 static bool io_acct_cancel_pending_work(struct io_wq *wq,
1056 struct io_wq_acct *acct,
1057 struct io_cb_cancel_data *match)
1058 {
1059 struct io_wq_work_node *node, *prev;
1060 struct io_wq_work *work;
1061
1062 raw_spin_lock(&acct->lock);
1063 wq_list_for_each(node, prev, &acct->work_list) {
1064 work = container_of(node, struct io_wq_work, list);
1065 if (!match->fn(work, match->data))
1066 continue;
1067 io_wq_remove_pending(wq, work, prev);
1068 raw_spin_unlock(&acct->lock);
1069 io_run_cancel(work, wq);
1070 match->nr_pending++;
1071 /* not safe to continue after unlock */
1072 return true;
1073 }
1074 raw_spin_unlock(&acct->lock);
1075
1076 return false;
1077 }
1078
io_wq_cancel_pending_work(struct io_wq * wq,struct io_cb_cancel_data * match)1079 static void io_wq_cancel_pending_work(struct io_wq *wq,
1080 struct io_cb_cancel_data *match)
1081 {
1082 int i;
1083 retry:
1084 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1085 struct io_wq_acct *acct = io_get_acct(wq, i == 0);
1086
1087 if (io_acct_cancel_pending_work(wq, acct, match)) {
1088 if (match->cancel_all)
1089 goto retry;
1090 break;
1091 }
1092 }
1093 }
1094
io_wq_cancel_running_work(struct io_wq * wq,struct io_cb_cancel_data * match)1095 static void io_wq_cancel_running_work(struct io_wq *wq,
1096 struct io_cb_cancel_data *match)
1097 {
1098 rcu_read_lock();
1099 io_wq_for_each_worker(wq, io_wq_worker_cancel, match);
1100 rcu_read_unlock();
1101 }
1102
io_wq_cancel_cb(struct io_wq * wq,work_cancel_fn * cancel,void * data,bool cancel_all)1103 enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
1104 void *data, bool cancel_all)
1105 {
1106 struct io_cb_cancel_data match = {
1107 .fn = cancel,
1108 .data = data,
1109 .cancel_all = cancel_all,
1110 };
1111
1112 /*
1113 * First check pending list, if we're lucky we can just remove it
1114 * from there. CANCEL_OK means that the work is returned as-new,
1115 * no completion will be posted for it.
1116 *
1117 * Then check if a free (going busy) or busy worker has the work
1118 * currently running. If we find it there, we'll return CANCEL_RUNNING
1119 * as an indication that we attempt to signal cancellation. The
1120 * completion will run normally in this case.
1121 *
1122 * Do both of these while holding the wq->lock, to ensure that
1123 * we'll find a work item regardless of state.
1124 */
1125 io_wq_cancel_pending_work(wq, &match);
1126 if (match.nr_pending && !match.cancel_all)
1127 return IO_WQ_CANCEL_OK;
1128
1129 raw_spin_lock(&wq->lock);
1130 io_wq_cancel_running_work(wq, &match);
1131 raw_spin_unlock(&wq->lock);
1132 if (match.nr_running && !match.cancel_all)
1133 return IO_WQ_CANCEL_RUNNING;
1134
1135 if (match.nr_running)
1136 return IO_WQ_CANCEL_RUNNING;
1137 if (match.nr_pending)
1138 return IO_WQ_CANCEL_OK;
1139 return IO_WQ_CANCEL_NOTFOUND;
1140 }
1141
io_wq_hash_wake(struct wait_queue_entry * wait,unsigned mode,int sync,void * key)1142 static int io_wq_hash_wake(struct wait_queue_entry *wait, unsigned mode,
1143 int sync, void *key)
1144 {
1145 struct io_wq *wq = container_of(wait, struct io_wq, wait);
1146 int i;
1147
1148 list_del_init(&wait->entry);
1149
1150 rcu_read_lock();
1151 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1152 struct io_wq_acct *acct = &wq->acct[i];
1153
1154 if (test_and_clear_bit(IO_ACCT_STALLED_BIT, &acct->flags))
1155 io_wq_activate_free_worker(wq, acct);
1156 }
1157 rcu_read_unlock();
1158 return 1;
1159 }
1160
io_wq_create(unsigned bounded,struct io_wq_data * data)1161 struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
1162 {
1163 int ret, i;
1164 struct io_wq *wq;
1165
1166 if (WARN_ON_ONCE(!data->free_work || !data->do_work))
1167 return ERR_PTR(-EINVAL);
1168 if (WARN_ON_ONCE(!bounded))
1169 return ERR_PTR(-EINVAL);
1170
1171 wq = kzalloc(sizeof(struct io_wq), GFP_KERNEL);
1172 if (!wq)
1173 return ERR_PTR(-ENOMEM);
1174
1175 refcount_inc(&data->hash->refs);
1176 wq->hash = data->hash;
1177 wq->free_work = data->free_work;
1178 wq->do_work = data->do_work;
1179
1180 ret = -ENOMEM;
1181
1182 if (!alloc_cpumask_var(&wq->cpu_mask, GFP_KERNEL))
1183 goto err;
1184 cpuset_cpus_allowed(data->task, wq->cpu_mask);
1185 wq->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
1186 wq->acct[IO_WQ_ACCT_UNBOUND].max_workers =
1187 task_rlimit(current, RLIMIT_NPROC);
1188 INIT_LIST_HEAD(&wq->wait.entry);
1189 wq->wait.func = io_wq_hash_wake;
1190 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1191 struct io_wq_acct *acct = &wq->acct[i];
1192
1193 acct->index = i;
1194 atomic_set(&acct->nr_running, 0);
1195 INIT_WQ_LIST(&acct->work_list);
1196 raw_spin_lock_init(&acct->lock);
1197 }
1198
1199 raw_spin_lock_init(&wq->lock);
1200 INIT_HLIST_NULLS_HEAD(&wq->free_list, 0);
1201 INIT_LIST_HEAD(&wq->all_list);
1202
1203 wq->task = get_task_struct(data->task);
1204 atomic_set(&wq->worker_refs, 1);
1205 init_completion(&wq->worker_done);
1206 ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1207 if (ret)
1208 goto err;
1209
1210 return wq;
1211 err:
1212 io_wq_put_hash(data->hash);
1213 free_cpumask_var(wq->cpu_mask);
1214 kfree(wq);
1215 return ERR_PTR(ret);
1216 }
1217
io_task_work_match(struct callback_head * cb,void * data)1218 static bool io_task_work_match(struct callback_head *cb, void *data)
1219 {
1220 struct io_worker *worker;
1221
1222 if (cb->func != create_worker_cb && cb->func != create_worker_cont)
1223 return false;
1224 worker = container_of(cb, struct io_worker, create_work);
1225 return worker->wq == data;
1226 }
1227
io_wq_exit_start(struct io_wq * wq)1228 void io_wq_exit_start(struct io_wq *wq)
1229 {
1230 set_bit(IO_WQ_BIT_EXIT, &wq->state);
1231 }
1232
io_wq_cancel_tw_create(struct io_wq * wq)1233 static void io_wq_cancel_tw_create(struct io_wq *wq)
1234 {
1235 struct callback_head *cb;
1236
1237 while ((cb = task_work_cancel_match(wq->task, io_task_work_match, wq)) != NULL) {
1238 struct io_worker *worker;
1239
1240 worker = container_of(cb, struct io_worker, create_work);
1241 io_worker_cancel_cb(worker);
1242 /*
1243 * Only the worker continuation helper has worker allocated and
1244 * hence needs freeing.
1245 */
1246 if (cb->func == create_worker_cont)
1247 kfree(worker);
1248 }
1249 }
1250
io_wq_exit_workers(struct io_wq * wq)1251 static void io_wq_exit_workers(struct io_wq *wq)
1252 {
1253 if (!wq->task)
1254 return;
1255
1256 io_wq_cancel_tw_create(wq);
1257
1258 rcu_read_lock();
1259 io_wq_for_each_worker(wq, io_wq_worker_wake, NULL);
1260 rcu_read_unlock();
1261 io_worker_ref_put(wq);
1262 wait_for_completion(&wq->worker_done);
1263
1264 spin_lock_irq(&wq->hash->wait.lock);
1265 list_del_init(&wq->wait.entry);
1266 spin_unlock_irq(&wq->hash->wait.lock);
1267
1268 put_task_struct(wq->task);
1269 wq->task = NULL;
1270 }
1271
io_wq_destroy(struct io_wq * wq)1272 static void io_wq_destroy(struct io_wq *wq)
1273 {
1274 struct io_cb_cancel_data match = {
1275 .fn = io_wq_work_match_all,
1276 .cancel_all = true,
1277 };
1278
1279 cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1280 io_wq_cancel_pending_work(wq, &match);
1281 free_cpumask_var(wq->cpu_mask);
1282 io_wq_put_hash(wq->hash);
1283 kfree(wq);
1284 }
1285
io_wq_put_and_exit(struct io_wq * wq)1286 void io_wq_put_and_exit(struct io_wq *wq)
1287 {
1288 WARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, &wq->state));
1289
1290 io_wq_exit_workers(wq);
1291 io_wq_destroy(wq);
1292 }
1293
1294 struct online_data {
1295 unsigned int cpu;
1296 bool online;
1297 };
1298
io_wq_worker_affinity(struct io_worker * worker,void * data)1299 static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
1300 {
1301 struct online_data *od = data;
1302
1303 if (od->online)
1304 cpumask_set_cpu(od->cpu, worker->wq->cpu_mask);
1305 else
1306 cpumask_clear_cpu(od->cpu, worker->wq->cpu_mask);
1307 return false;
1308 }
1309
__io_wq_cpu_online(struct io_wq * wq,unsigned int cpu,bool online)1310 static int __io_wq_cpu_online(struct io_wq *wq, unsigned int cpu, bool online)
1311 {
1312 struct online_data od = {
1313 .cpu = cpu,
1314 .online = online
1315 };
1316
1317 rcu_read_lock();
1318 io_wq_for_each_worker(wq, io_wq_worker_affinity, &od);
1319 rcu_read_unlock();
1320 return 0;
1321 }
1322
io_wq_cpu_online(unsigned int cpu,struct hlist_node * node)1323 static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
1324 {
1325 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1326
1327 return __io_wq_cpu_online(wq, cpu, true);
1328 }
1329
io_wq_cpu_offline(unsigned int cpu,struct hlist_node * node)1330 static int io_wq_cpu_offline(unsigned int cpu, struct hlist_node *node)
1331 {
1332 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1333
1334 return __io_wq_cpu_online(wq, cpu, false);
1335 }
1336
io_wq_cpu_affinity(struct io_uring_task * tctx,cpumask_var_t mask)1337 int io_wq_cpu_affinity(struct io_uring_task *tctx, cpumask_var_t mask)
1338 {
1339 cpumask_var_t allowed_mask;
1340 int ret = 0;
1341
1342 if (!tctx || !tctx->io_wq)
1343 return -EINVAL;
1344
1345 if (!alloc_cpumask_var(&allowed_mask, GFP_KERNEL))
1346 return -ENOMEM;
1347
1348 rcu_read_lock();
1349 cpuset_cpus_allowed(tctx->io_wq->task, allowed_mask);
1350 if (mask) {
1351 if (cpumask_subset(mask, allowed_mask))
1352 cpumask_copy(tctx->io_wq->cpu_mask, mask);
1353 else
1354 ret = -EINVAL;
1355 } else {
1356 cpumask_copy(tctx->io_wq->cpu_mask, allowed_mask);
1357 }
1358 rcu_read_unlock();
1359
1360 free_cpumask_var(allowed_mask);
1361 return ret;
1362 }
1363
1364 /*
1365 * Set max number of unbounded workers, returns old value. If new_count is 0,
1366 * then just return the old value.
1367 */
io_wq_max_workers(struct io_wq * wq,int * new_count)1368 int io_wq_max_workers(struct io_wq *wq, int *new_count)
1369 {
1370 struct io_wq_acct *acct;
1371 int prev[IO_WQ_ACCT_NR];
1372 int i;
1373
1374 BUILD_BUG_ON((int) IO_WQ_ACCT_BOUND != (int) IO_WQ_BOUND);
1375 BUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND);
1376 BUILD_BUG_ON((int) IO_WQ_ACCT_NR != 2);
1377
1378 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1379 if (new_count[i] > task_rlimit(current, RLIMIT_NPROC))
1380 new_count[i] = task_rlimit(current, RLIMIT_NPROC);
1381 }
1382
1383 for (i = 0; i < IO_WQ_ACCT_NR; i++)
1384 prev[i] = 0;
1385
1386 rcu_read_lock();
1387
1388 raw_spin_lock(&wq->lock);
1389 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1390 acct = &wq->acct[i];
1391 prev[i] = max_t(int, acct->max_workers, prev[i]);
1392 if (new_count[i])
1393 acct->max_workers = new_count[i];
1394 }
1395 raw_spin_unlock(&wq->lock);
1396 rcu_read_unlock();
1397
1398 for (i = 0; i < IO_WQ_ACCT_NR; i++)
1399 new_count[i] = prev[i];
1400
1401 return 0;
1402 }
1403
io_wq_init(void)1404 static __init int io_wq_init(void)
1405 {
1406 int ret;
1407
1408 ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "io-wq/online",
1409 io_wq_cpu_online, io_wq_cpu_offline);
1410 if (ret < 0)
1411 return ret;
1412 io_wq_online = ret;
1413 return 0;
1414 }
1415 subsys_initcall(io_wq_init);
1416