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 };
34
35 enum {
36 IO_WQ_BIT_EXIT = 0, /* wq exiting */
37 };
38
39 enum {
40 IO_ACCT_STALLED_BIT = 0, /* stalled on hash */
41 };
42
43 /*
44 * One for each thread in a wq pool
45 */
46 struct io_worker {
47 refcount_t ref;
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 struct io_wq_acct *acct;
54
55 struct io_wq_work *cur_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 int init_retries;
63
64 union {
65 struct rcu_head rcu;
66 struct delayed_work work;
67 };
68 };
69
70 #if BITS_PER_LONG == 64
71 #define IO_WQ_HASH_ORDER 6
72 #else
73 #define IO_WQ_HASH_ORDER 5
74 #endif
75
76 #define IO_WQ_NR_HASH_BUCKETS (1u << IO_WQ_HASH_ORDER)
77
78 struct io_wq_acct {
79 /**
80 * Protects access to the worker lists.
81 */
82 raw_spinlock_t workers_lock;
83
84 unsigned nr_workers;
85 unsigned max_workers;
86 atomic_t nr_running;
87
88 /**
89 * The list of free workers. Protected by #workers_lock
90 * (write) and RCU (read).
91 */
92 struct hlist_nulls_head free_list;
93
94 /**
95 * The list of all workers. Protected by #workers_lock
96 * (write) and RCU (read).
97 */
98 struct list_head all_list;
99
100 raw_spinlock_t lock;
101 struct io_wq_work_list work_list;
102 unsigned long flags;
103 };
104
105 enum {
106 IO_WQ_ACCT_BOUND,
107 IO_WQ_ACCT_UNBOUND,
108 IO_WQ_ACCT_NR,
109 };
110
111 /*
112 * Per io_wq state
113 */
114 struct io_wq {
115 unsigned long state;
116
117 free_work_fn *free_work;
118 io_wq_work_fn *do_work;
119
120 struct io_wq_hash *hash;
121
122 atomic_t worker_refs;
123 struct completion worker_done;
124
125 struct hlist_node cpuhp_node;
126
127 struct task_struct *task;
128
129 struct io_wq_acct acct[IO_WQ_ACCT_NR];
130
131 struct wait_queue_entry wait;
132
133 struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
134
135 cpumask_var_t cpu_mask;
136 };
137
138 static enum cpuhp_state io_wq_online;
139
140 struct io_cb_cancel_data {
141 work_cancel_fn *fn;
142 void *data;
143 int nr_running;
144 int nr_pending;
145 bool cancel_all;
146 };
147
148 static bool create_io_worker(struct io_wq *wq, struct io_wq_acct *acct);
149 static void io_wq_dec_running(struct io_worker *worker);
150 static bool io_acct_cancel_pending_work(struct io_wq *wq,
151 struct io_wq_acct *acct,
152 struct io_cb_cancel_data *match);
153 static void create_worker_cb(struct callback_head *cb);
154 static void io_wq_cancel_tw_create(struct io_wq *wq);
155
io_worker_get(struct io_worker * worker)156 static bool io_worker_get(struct io_worker *worker)
157 {
158 return refcount_inc_not_zero(&worker->ref);
159 }
160
io_worker_release(struct io_worker * worker)161 static void io_worker_release(struct io_worker *worker)
162 {
163 if (refcount_dec_and_test(&worker->ref))
164 complete(&worker->ref_done);
165 }
166
io_get_acct(struct io_wq * wq,bool bound)167 static inline struct io_wq_acct *io_get_acct(struct io_wq *wq, bool bound)
168 {
169 return &wq->acct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND];
170 }
171
io_work_get_acct(struct io_wq * wq,unsigned int work_flags)172 static inline struct io_wq_acct *io_work_get_acct(struct io_wq *wq,
173 unsigned int work_flags)
174 {
175 return io_get_acct(wq, !(work_flags & IO_WQ_WORK_UNBOUND));
176 }
177
io_wq_get_acct(struct io_worker * worker)178 static inline struct io_wq_acct *io_wq_get_acct(struct io_worker *worker)
179 {
180 return worker->acct;
181 }
182
io_worker_ref_put(struct io_wq * wq)183 static void io_worker_ref_put(struct io_wq *wq)
184 {
185 if (atomic_dec_and_test(&wq->worker_refs))
186 complete(&wq->worker_done);
187 }
188
io_wq_worker_stopped(void)189 bool io_wq_worker_stopped(void)
190 {
191 struct io_worker *worker = current->worker_private;
192
193 if (WARN_ON_ONCE(!io_wq_current_is_worker()))
194 return true;
195
196 return test_bit(IO_WQ_BIT_EXIT, &worker->wq->state);
197 }
198
io_worker_cancel_cb(struct io_worker * worker)199 static void io_worker_cancel_cb(struct io_worker *worker)
200 {
201 struct io_wq_acct *acct = io_wq_get_acct(worker);
202 struct io_wq *wq = worker->wq;
203
204 atomic_dec(&acct->nr_running);
205 raw_spin_lock(&acct->workers_lock);
206 acct->nr_workers--;
207 raw_spin_unlock(&acct->workers_lock);
208 io_worker_ref_put(wq);
209 clear_bit_unlock(0, &worker->create_state);
210 io_worker_release(worker);
211 }
212
io_task_worker_match(struct callback_head * cb,void * data)213 static bool io_task_worker_match(struct callback_head *cb, void *data)
214 {
215 struct io_worker *worker;
216
217 if (cb->func != create_worker_cb)
218 return false;
219 worker = container_of(cb, struct io_worker, create_work);
220 return worker == data;
221 }
222
io_worker_exit(struct io_worker * worker)223 static void io_worker_exit(struct io_worker *worker)
224 {
225 struct io_wq *wq = worker->wq;
226 struct io_wq_acct *acct = io_wq_get_acct(worker);
227
228 while (1) {
229 struct callback_head *cb = task_work_cancel_match(wq->task,
230 io_task_worker_match, worker);
231
232 if (!cb)
233 break;
234 io_worker_cancel_cb(worker);
235 }
236
237 io_worker_release(worker);
238 wait_for_completion(&worker->ref_done);
239
240 raw_spin_lock(&acct->workers_lock);
241 if (test_bit(IO_WORKER_F_FREE, &worker->flags))
242 hlist_nulls_del_rcu(&worker->nulls_node);
243 list_del_rcu(&worker->all_list);
244 raw_spin_unlock(&acct->workers_lock);
245 io_wq_dec_running(worker);
246 /*
247 * this worker is a goner, clear ->worker_private to avoid any
248 * inc/dec running calls that could happen as part of exit from
249 * touching 'worker'.
250 */
251 current->worker_private = NULL;
252
253 kfree_rcu(worker, rcu);
254 io_worker_ref_put(wq);
255 do_exit(0);
256 }
257
__io_acct_run_queue(struct io_wq_acct * acct)258 static inline bool __io_acct_run_queue(struct io_wq_acct *acct)
259 {
260 return !test_bit(IO_ACCT_STALLED_BIT, &acct->flags) &&
261 !wq_list_empty(&acct->work_list);
262 }
263
264 /*
265 * If there's work to do, returns true with acct->lock acquired. If not,
266 * returns false with no lock held.
267 */
io_acct_run_queue(struct io_wq_acct * acct)268 static inline bool io_acct_run_queue(struct io_wq_acct *acct)
269 __acquires(&acct->lock)
270 {
271 raw_spin_lock(&acct->lock);
272 if (__io_acct_run_queue(acct))
273 return true;
274
275 raw_spin_unlock(&acct->lock);
276 return false;
277 }
278
279 /*
280 * Check head of free list for an available worker. If one isn't available,
281 * caller must create one.
282 */
io_acct_activate_free_worker(struct io_wq_acct * acct)283 static bool io_acct_activate_free_worker(struct io_wq_acct *acct)
284 __must_hold(RCU)
285 {
286 struct hlist_nulls_node *n;
287 struct io_worker *worker;
288
289 /*
290 * Iterate free_list and see if we can find an idle worker to
291 * activate. If a given worker is on the free_list but in the process
292 * of exiting, keep trying.
293 */
294 hlist_nulls_for_each_entry_rcu(worker, n, &acct->free_list, nulls_node) {
295 if (!io_worker_get(worker))
296 continue;
297 /*
298 * If the worker is already running, it's either already
299 * starting work or finishing work. In either case, if it does
300 * to go sleep, we'll kick off a new task for this work anyway.
301 */
302 wake_up_process(worker->task);
303 io_worker_release(worker);
304 return true;
305 }
306
307 return false;
308 }
309
310 /*
311 * We need a worker. If we find a free one, we're good. If not, and we're
312 * below the max number of workers, create one.
313 */
io_wq_create_worker(struct io_wq * wq,struct io_wq_acct * acct)314 static bool io_wq_create_worker(struct io_wq *wq, struct io_wq_acct *acct)
315 {
316 /*
317 * Most likely an attempt to queue unbounded work on an io_wq that
318 * wasn't setup with any unbounded workers.
319 */
320 if (unlikely(!acct->max_workers))
321 pr_warn_once("io-wq is not configured for unbound workers");
322
323 raw_spin_lock(&acct->workers_lock);
324 if (acct->nr_workers >= acct->max_workers) {
325 raw_spin_unlock(&acct->workers_lock);
326 return true;
327 }
328 acct->nr_workers++;
329 raw_spin_unlock(&acct->workers_lock);
330 atomic_inc(&acct->nr_running);
331 atomic_inc(&wq->worker_refs);
332 return create_io_worker(wq, acct);
333 }
334
io_wq_inc_running(struct io_worker * worker)335 static void io_wq_inc_running(struct io_worker *worker)
336 {
337 struct io_wq_acct *acct = io_wq_get_acct(worker);
338
339 atomic_inc(&acct->nr_running);
340 }
341
create_worker_cb(struct callback_head * cb)342 static void create_worker_cb(struct callback_head *cb)
343 {
344 struct io_worker *worker;
345 struct io_wq *wq;
346
347 struct io_wq_acct *acct;
348 bool do_create = false;
349
350 worker = container_of(cb, struct io_worker, create_work);
351 wq = worker->wq;
352 acct = worker->acct;
353 raw_spin_lock(&acct->workers_lock);
354
355 if (acct->nr_workers < acct->max_workers) {
356 acct->nr_workers++;
357 do_create = true;
358 }
359 raw_spin_unlock(&acct->workers_lock);
360 if (do_create) {
361 create_io_worker(wq, acct);
362 } else {
363 atomic_dec(&acct->nr_running);
364 io_worker_ref_put(wq);
365 }
366 clear_bit_unlock(0, &worker->create_state);
367 io_worker_release(worker);
368 }
369
io_queue_worker_create(struct io_worker * worker,struct io_wq_acct * acct,task_work_func_t func)370 static bool io_queue_worker_create(struct io_worker *worker,
371 struct io_wq_acct *acct,
372 task_work_func_t func)
373 {
374 struct io_wq *wq = worker->wq;
375
376 /* raced with exit, just ignore create call */
377 if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
378 goto fail;
379 if (!io_worker_get(worker))
380 goto fail;
381 /*
382 * create_state manages ownership of create_work/index. We should
383 * only need one entry per worker, as the worker going to sleep
384 * will trigger the condition, and waking will clear it once it
385 * runs the task_work.
386 */
387 if (test_bit(0, &worker->create_state) ||
388 test_and_set_bit_lock(0, &worker->create_state))
389 goto fail_release;
390
391 atomic_inc(&wq->worker_refs);
392 init_task_work(&worker->create_work, func);
393 if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
394 /*
395 * EXIT may have been set after checking it above, check after
396 * adding the task_work and remove any creation item if it is
397 * now set. wq exit does that too, but we can have added this
398 * work item after we canceled in io_wq_exit_workers().
399 */
400 if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
401 io_wq_cancel_tw_create(wq);
402 io_worker_ref_put(wq);
403 return true;
404 }
405 io_worker_ref_put(wq);
406 clear_bit_unlock(0, &worker->create_state);
407 fail_release:
408 io_worker_release(worker);
409 fail:
410 atomic_dec(&acct->nr_running);
411 io_worker_ref_put(wq);
412 return false;
413 }
414
io_wq_dec_running(struct io_worker * worker)415 static void io_wq_dec_running(struct io_worker *worker)
416 {
417 struct io_wq_acct *acct = io_wq_get_acct(worker);
418 struct io_wq *wq = worker->wq;
419
420 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
421 return;
422
423 if (!atomic_dec_and_test(&acct->nr_running))
424 return;
425 if (!io_acct_run_queue(acct))
426 return;
427
428 raw_spin_unlock(&acct->lock);
429 atomic_inc(&acct->nr_running);
430 atomic_inc(&wq->worker_refs);
431 io_queue_worker_create(worker, acct, create_worker_cb);
432 }
433
434 /*
435 * Worker will start processing some work. Move it to the busy list, if
436 * it's currently on the freelist
437 */
__io_worker_busy(struct io_wq_acct * acct,struct io_worker * worker)438 static void __io_worker_busy(struct io_wq_acct *acct, struct io_worker *worker)
439 {
440 if (test_bit(IO_WORKER_F_FREE, &worker->flags)) {
441 clear_bit(IO_WORKER_F_FREE, &worker->flags);
442 raw_spin_lock(&acct->workers_lock);
443 hlist_nulls_del_init_rcu(&worker->nulls_node);
444 raw_spin_unlock(&acct->workers_lock);
445 }
446 }
447
448 /*
449 * No work, worker going to sleep. Move to freelist.
450 */
__io_worker_idle(struct io_wq_acct * acct,struct io_worker * worker)451 static void __io_worker_idle(struct io_wq_acct *acct, struct io_worker *worker)
452 __must_hold(acct->workers_lock)
453 {
454 if (!test_bit(IO_WORKER_F_FREE, &worker->flags)) {
455 set_bit(IO_WORKER_F_FREE, &worker->flags);
456 hlist_nulls_add_head_rcu(&worker->nulls_node, &acct->free_list);
457 }
458 }
459
__io_get_work_hash(unsigned int work_flags)460 static inline unsigned int __io_get_work_hash(unsigned int work_flags)
461 {
462 return work_flags >> IO_WQ_HASH_SHIFT;
463 }
464
io_get_work_hash(struct io_wq_work * work)465 static inline unsigned int io_get_work_hash(struct io_wq_work *work)
466 {
467 return __io_get_work_hash(atomic_read(&work->flags));
468 }
469
io_wait_on_hash(struct io_wq * wq,unsigned int hash)470 static bool io_wait_on_hash(struct io_wq *wq, unsigned int hash)
471 {
472 bool ret = false;
473
474 spin_lock_irq(&wq->hash->wait.lock);
475 if (list_empty(&wq->wait.entry)) {
476 __add_wait_queue(&wq->hash->wait, &wq->wait);
477 if (!test_bit(hash, &wq->hash->map)) {
478 __set_current_state(TASK_RUNNING);
479 list_del_init(&wq->wait.entry);
480 ret = true;
481 }
482 }
483 spin_unlock_irq(&wq->hash->wait.lock);
484 return ret;
485 }
486
io_get_next_work(struct io_wq_acct * acct,struct io_wq * wq)487 static struct io_wq_work *io_get_next_work(struct io_wq_acct *acct,
488 struct io_wq *wq)
489 __must_hold(acct->lock)
490 {
491 struct io_wq_work_node *node, *prev;
492 struct io_wq_work *work, *tail;
493 unsigned int stall_hash = -1U;
494
495 wq_list_for_each(node, prev, &acct->work_list) {
496 unsigned int work_flags;
497 unsigned int hash;
498
499 work = container_of(node, struct io_wq_work, list);
500
501 /* not hashed, can run anytime */
502 work_flags = atomic_read(&work->flags);
503 if (!__io_wq_is_hashed(work_flags)) {
504 wq_list_del(&acct->work_list, node, prev);
505 return work;
506 }
507
508 hash = __io_get_work_hash(work_flags);
509 /* all items with this hash lie in [work, tail] */
510 tail = wq->hash_tail[hash];
511
512 /* hashed, can run if not already running */
513 if (!test_and_set_bit(hash, &wq->hash->map)) {
514 wq->hash_tail[hash] = NULL;
515 wq_list_cut(&acct->work_list, &tail->list, prev);
516 return work;
517 }
518 if (stall_hash == -1U)
519 stall_hash = hash;
520 /* fast forward to a next hash, for-each will fix up @prev */
521 node = &tail->list;
522 }
523
524 if (stall_hash != -1U) {
525 bool unstalled;
526
527 /*
528 * Set this before dropping the lock to avoid racing with new
529 * work being added and clearing the stalled bit.
530 */
531 set_bit(IO_ACCT_STALLED_BIT, &acct->flags);
532 raw_spin_unlock(&acct->lock);
533 unstalled = io_wait_on_hash(wq, stall_hash);
534 raw_spin_lock(&acct->lock);
535 if (unstalled) {
536 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
537 if (wq_has_sleeper(&wq->hash->wait))
538 wake_up(&wq->hash->wait);
539 }
540 }
541
542 return NULL;
543 }
544
io_assign_current_work(struct io_worker * worker,struct io_wq_work * work)545 static void io_assign_current_work(struct io_worker *worker,
546 struct io_wq_work *work)
547 {
548 if (work) {
549 io_run_task_work();
550 cond_resched();
551 }
552
553 raw_spin_lock(&worker->lock);
554 worker->cur_work = work;
555 raw_spin_unlock(&worker->lock);
556 }
557
558 /*
559 * Called with acct->lock held, drops it before returning
560 */
io_worker_handle_work(struct io_wq_acct * acct,struct io_worker * worker)561 static void io_worker_handle_work(struct io_wq_acct *acct,
562 struct io_worker *worker)
563 __releases(&acct->lock)
564 {
565 struct io_wq *wq = worker->wq;
566 bool do_kill = test_bit(IO_WQ_BIT_EXIT, &wq->state);
567
568 do {
569 struct io_wq_work *work;
570
571 /*
572 * If we got some work, mark us as busy. If we didn't, but
573 * the list isn't empty, it means we stalled on hashed work.
574 * Mark us stalled so we don't keep looking for work when we
575 * can't make progress, any work completion or insertion will
576 * clear the stalled flag.
577 */
578 work = io_get_next_work(acct, wq);
579 if (work) {
580 /*
581 * Make sure cancelation can find this, even before
582 * it becomes the active work. That avoids a window
583 * where the work has been removed from our general
584 * work list, but isn't yet discoverable as the
585 * current work item for this worker.
586 */
587 raw_spin_lock(&worker->lock);
588 worker->cur_work = work;
589 raw_spin_unlock(&worker->lock);
590 }
591
592 raw_spin_unlock(&acct->lock);
593
594 if (!work)
595 break;
596
597 __io_worker_busy(acct, worker);
598
599 io_assign_current_work(worker, work);
600 __set_current_state(TASK_RUNNING);
601
602 /* handle a whole dependent link */
603 do {
604 struct io_wq_work *next_hashed, *linked;
605 unsigned int work_flags = atomic_read(&work->flags);
606 unsigned int hash = __io_wq_is_hashed(work_flags)
607 ? __io_get_work_hash(work_flags)
608 : -1U;
609
610 next_hashed = wq_next_work(work);
611
612 if (do_kill &&
613 (work_flags & IO_WQ_WORK_UNBOUND))
614 atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
615 wq->do_work(work);
616 io_assign_current_work(worker, NULL);
617
618 linked = wq->free_work(work);
619 work = next_hashed;
620 if (!work && linked && !io_wq_is_hashed(linked)) {
621 work = linked;
622 linked = NULL;
623 }
624 io_assign_current_work(worker, work);
625 if (linked)
626 io_wq_enqueue(wq, linked);
627
628 if (hash != -1U && !next_hashed) {
629 /* serialize hash clear with wake_up() */
630 spin_lock_irq(&wq->hash->wait.lock);
631 clear_bit(hash, &wq->hash->map);
632 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
633 spin_unlock_irq(&wq->hash->wait.lock);
634 if (wq_has_sleeper(&wq->hash->wait))
635 wake_up(&wq->hash->wait);
636 }
637 } while (work);
638
639 if (!__io_acct_run_queue(acct))
640 break;
641 raw_spin_lock(&acct->lock);
642 } while (1);
643 }
644
io_wq_worker(void * data)645 static int io_wq_worker(void *data)
646 {
647 struct io_worker *worker = data;
648 struct io_wq_acct *acct = io_wq_get_acct(worker);
649 struct io_wq *wq = worker->wq;
650 bool exit_mask = false, last_timeout = false;
651 char buf[TASK_COMM_LEN] = {};
652
653 set_mask_bits(&worker->flags, 0,
654 BIT(IO_WORKER_F_UP) | BIT(IO_WORKER_F_RUNNING));
655
656 snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid);
657 set_task_comm(current, buf);
658
659 while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
660 long ret;
661
662 set_current_state(TASK_INTERRUPTIBLE);
663
664 /*
665 * If we have work to do, io_acct_run_queue() returns with
666 * the acct->lock held. If not, it will drop it.
667 */
668 while (io_acct_run_queue(acct))
669 io_worker_handle_work(acct, worker);
670
671 raw_spin_lock(&acct->workers_lock);
672 /*
673 * Last sleep timed out. Exit if we're not the last worker,
674 * or if someone modified our affinity.
675 */
676 if (last_timeout && (exit_mask || acct->nr_workers > 1)) {
677 acct->nr_workers--;
678 raw_spin_unlock(&acct->workers_lock);
679 __set_current_state(TASK_RUNNING);
680 break;
681 }
682 last_timeout = false;
683 __io_worker_idle(acct, worker);
684 raw_spin_unlock(&acct->workers_lock);
685 if (io_run_task_work())
686 continue;
687 ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
688 if (signal_pending(current)) {
689 struct ksignal ksig;
690
691 if (!get_signal(&ksig))
692 continue;
693 break;
694 }
695 if (!ret) {
696 last_timeout = true;
697 exit_mask = !cpumask_test_cpu(raw_smp_processor_id(),
698 wq->cpu_mask);
699 }
700 }
701
702 if (test_bit(IO_WQ_BIT_EXIT, &wq->state) && io_acct_run_queue(acct))
703 io_worker_handle_work(acct, worker);
704
705 io_worker_exit(worker);
706 return 0;
707 }
708
709 /*
710 * Called when a worker is scheduled in. Mark us as currently running.
711 */
io_wq_worker_running(struct task_struct * tsk)712 void io_wq_worker_running(struct task_struct *tsk)
713 {
714 struct io_worker *worker = tsk->worker_private;
715
716 if (!worker)
717 return;
718 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
719 return;
720 if (test_bit(IO_WORKER_F_RUNNING, &worker->flags))
721 return;
722 set_bit(IO_WORKER_F_RUNNING, &worker->flags);
723 io_wq_inc_running(worker);
724 }
725
726 /*
727 * Called when worker is going to sleep. If there are no workers currently
728 * running and we have work pending, wake up a free one or create a new one.
729 */
io_wq_worker_sleeping(struct task_struct * tsk)730 void io_wq_worker_sleeping(struct task_struct *tsk)
731 {
732 struct io_worker *worker = tsk->worker_private;
733
734 if (!worker)
735 return;
736 if (!test_bit(IO_WORKER_F_UP, &worker->flags))
737 return;
738 if (!test_bit(IO_WORKER_F_RUNNING, &worker->flags))
739 return;
740
741 clear_bit(IO_WORKER_F_RUNNING, &worker->flags);
742 io_wq_dec_running(worker);
743 }
744
io_init_new_worker(struct io_wq * wq,struct io_wq_acct * acct,struct io_worker * worker,struct task_struct * tsk)745 static void io_init_new_worker(struct io_wq *wq, struct io_wq_acct *acct, struct io_worker *worker,
746 struct task_struct *tsk)
747 {
748 tsk->worker_private = worker;
749 worker->task = tsk;
750 set_cpus_allowed_ptr(tsk, wq->cpu_mask);
751
752 raw_spin_lock(&acct->workers_lock);
753 hlist_nulls_add_head_rcu(&worker->nulls_node, &acct->free_list);
754 list_add_tail_rcu(&worker->all_list, &acct->all_list);
755 set_bit(IO_WORKER_F_FREE, &worker->flags);
756 raw_spin_unlock(&acct->workers_lock);
757 wake_up_new_task(tsk);
758 }
759
io_wq_work_match_all(struct io_wq_work * work,void * data)760 static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
761 {
762 return true;
763 }
764
io_should_retry_thread(struct io_worker * worker,long err)765 static inline bool io_should_retry_thread(struct io_worker *worker, long err)
766 {
767 /*
768 * Prevent perpetual task_work retry, if the task (or its group) is
769 * exiting.
770 */
771 if (fatal_signal_pending(current))
772 return false;
773 if (worker->init_retries++ >= WORKER_INIT_LIMIT)
774 return false;
775
776 switch (err) {
777 case -EAGAIN:
778 case -ERESTARTSYS:
779 case -ERESTARTNOINTR:
780 case -ERESTARTNOHAND:
781 return true;
782 default:
783 return false;
784 }
785 }
786
queue_create_worker_retry(struct io_worker * worker)787 static void queue_create_worker_retry(struct io_worker *worker)
788 {
789 /*
790 * We only bother retrying because there's a chance that the
791 * failure to create a worker is due to some temporary condition
792 * in the forking task (e.g. outstanding signal); give the task
793 * some time to clear that condition.
794 */
795 schedule_delayed_work(&worker->work,
796 msecs_to_jiffies(worker->init_retries * 5));
797 }
798
create_worker_cont(struct callback_head * cb)799 static void create_worker_cont(struct callback_head *cb)
800 {
801 struct io_worker *worker;
802 struct task_struct *tsk;
803 struct io_wq *wq;
804 struct io_wq_acct *acct;
805
806 worker = container_of(cb, struct io_worker, create_work);
807 clear_bit_unlock(0, &worker->create_state);
808 wq = worker->wq;
809 acct = io_wq_get_acct(worker);
810 tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE);
811 if (!IS_ERR(tsk)) {
812 io_init_new_worker(wq, acct, worker, tsk);
813 io_worker_release(worker);
814 return;
815 } else if (!io_should_retry_thread(worker, PTR_ERR(tsk))) {
816 atomic_dec(&acct->nr_running);
817 raw_spin_lock(&acct->workers_lock);
818 acct->nr_workers--;
819 if (!acct->nr_workers) {
820 struct io_cb_cancel_data match = {
821 .fn = io_wq_work_match_all,
822 .cancel_all = true,
823 };
824
825 raw_spin_unlock(&acct->workers_lock);
826 while (io_acct_cancel_pending_work(wq, acct, &match))
827 ;
828 } else {
829 raw_spin_unlock(&acct->workers_lock);
830 }
831 io_worker_ref_put(wq);
832 kfree(worker);
833 return;
834 }
835
836 /* re-create attempts grab a new worker ref, drop the existing one */
837 io_worker_release(worker);
838 queue_create_worker_retry(worker);
839 }
840
io_workqueue_create(struct work_struct * work)841 static void io_workqueue_create(struct work_struct *work)
842 {
843 struct io_worker *worker = container_of(work, struct io_worker,
844 work.work);
845 struct io_wq_acct *acct = io_wq_get_acct(worker);
846
847 if (!io_queue_worker_create(worker, acct, create_worker_cont))
848 kfree(worker);
849 }
850
create_io_worker(struct io_wq * wq,struct io_wq_acct * acct)851 static bool create_io_worker(struct io_wq *wq, struct io_wq_acct *acct)
852 {
853 struct io_worker *worker;
854 struct task_struct *tsk;
855
856 __set_current_state(TASK_RUNNING);
857
858 worker = kzalloc(sizeof(*worker), GFP_KERNEL);
859 if (!worker) {
860 fail:
861 atomic_dec(&acct->nr_running);
862 raw_spin_lock(&acct->workers_lock);
863 acct->nr_workers--;
864 raw_spin_unlock(&acct->workers_lock);
865 io_worker_ref_put(wq);
866 return false;
867 }
868
869 refcount_set(&worker->ref, 1);
870 worker->wq = wq;
871 worker->acct = acct;
872 raw_spin_lock_init(&worker->lock);
873 init_completion(&worker->ref_done);
874
875 tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE);
876 if (!IS_ERR(tsk)) {
877 io_init_new_worker(wq, acct, worker, tsk);
878 } else if (!io_should_retry_thread(worker, PTR_ERR(tsk))) {
879 kfree(worker);
880 goto fail;
881 } else {
882 INIT_DELAYED_WORK(&worker->work, io_workqueue_create);
883 queue_create_worker_retry(worker);
884 }
885
886 return true;
887 }
888
889 /*
890 * Iterate the passed in list and call the specific function for each
891 * worker that isn't exiting
892 */
io_acct_for_each_worker(struct io_wq_acct * acct,bool (* func)(struct io_worker *,void *),void * data)893 static bool io_acct_for_each_worker(struct io_wq_acct *acct,
894 bool (*func)(struct io_worker *, void *),
895 void *data)
896 {
897 struct io_worker *worker;
898 bool ret = false;
899
900 list_for_each_entry_rcu(worker, &acct->all_list, all_list) {
901 if (io_worker_get(worker)) {
902 /* no task if node is/was offline */
903 if (worker->task)
904 ret = func(worker, data);
905 io_worker_release(worker);
906 if (ret)
907 break;
908 }
909 }
910
911 return ret;
912 }
913
io_wq_for_each_worker(struct io_wq * wq,bool (* func)(struct io_worker *,void *),void * data)914 static bool io_wq_for_each_worker(struct io_wq *wq,
915 bool (*func)(struct io_worker *, void *),
916 void *data)
917 {
918 for (int i = 0; i < IO_WQ_ACCT_NR; i++) {
919 if (!io_acct_for_each_worker(&wq->acct[i], func, data))
920 return false;
921 }
922
923 return true;
924 }
925
io_wq_worker_wake(struct io_worker * worker,void * data)926 static bool io_wq_worker_wake(struct io_worker *worker, void *data)
927 {
928 __set_notify_signal(worker->task);
929 wake_up_process(worker->task);
930 return false;
931 }
932
io_run_cancel(struct io_wq_work * work,struct io_wq * wq)933 static void io_run_cancel(struct io_wq_work *work, struct io_wq *wq)
934 {
935 do {
936 atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
937 wq->do_work(work);
938 work = wq->free_work(work);
939 } while (work);
940 }
941
io_wq_insert_work(struct io_wq * wq,struct io_wq_acct * acct,struct io_wq_work * work,unsigned int work_flags)942 static void io_wq_insert_work(struct io_wq *wq, struct io_wq_acct *acct,
943 struct io_wq_work *work, unsigned int work_flags)
944 {
945 unsigned int hash;
946 struct io_wq_work *tail;
947
948 if (!__io_wq_is_hashed(work_flags)) {
949 append:
950 wq_list_add_tail(&work->list, &acct->work_list);
951 return;
952 }
953
954 hash = __io_get_work_hash(work_flags);
955 tail = wq->hash_tail[hash];
956 wq->hash_tail[hash] = work;
957 if (!tail)
958 goto append;
959
960 wq_list_add_after(&work->list, &tail->list, &acct->work_list);
961 }
962
io_wq_work_match_item(struct io_wq_work * work,void * data)963 static bool io_wq_work_match_item(struct io_wq_work *work, void *data)
964 {
965 return work == data;
966 }
967
io_wq_enqueue(struct io_wq * wq,struct io_wq_work * work)968 void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
969 {
970 unsigned int work_flags = atomic_read(&work->flags);
971 struct io_wq_acct *acct = io_work_get_acct(wq, work_flags);
972 struct io_cb_cancel_data match = {
973 .fn = io_wq_work_match_item,
974 .data = work,
975 .cancel_all = false,
976 };
977 bool do_create;
978
979 /*
980 * If io-wq is exiting for this task, or if the request has explicitly
981 * been marked as one that should not get executed, cancel it here.
982 */
983 if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
984 (work_flags & IO_WQ_WORK_CANCEL)) {
985 io_run_cancel(work, wq);
986 return;
987 }
988
989 raw_spin_lock(&acct->lock);
990 io_wq_insert_work(wq, acct, work, work_flags);
991 clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
992 raw_spin_unlock(&acct->lock);
993
994 rcu_read_lock();
995 do_create = !io_acct_activate_free_worker(acct);
996 rcu_read_unlock();
997
998 if (do_create && ((work_flags & IO_WQ_WORK_CONCURRENT) ||
999 !atomic_read(&acct->nr_running))) {
1000 bool did_create;
1001
1002 did_create = io_wq_create_worker(wq, acct);
1003 if (likely(did_create))
1004 return;
1005
1006 raw_spin_lock(&acct->workers_lock);
1007 if (acct->nr_workers) {
1008 raw_spin_unlock(&acct->workers_lock);
1009 return;
1010 }
1011 raw_spin_unlock(&acct->workers_lock);
1012
1013 /* fatal condition, failed to create the first worker */
1014 io_acct_cancel_pending_work(wq, acct, &match);
1015 }
1016 }
1017
1018 /*
1019 * Work items that hash to the same value will not be done in parallel.
1020 * Used to limit concurrent writes, generally hashed by inode.
1021 */
io_wq_hash_work(struct io_wq_work * work,void * val)1022 void io_wq_hash_work(struct io_wq_work *work, void *val)
1023 {
1024 unsigned int bit;
1025
1026 bit = hash_ptr(val, IO_WQ_HASH_ORDER);
1027 atomic_or(IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT), &work->flags);
1028 }
1029
__io_wq_worker_cancel(struct io_worker * worker,struct io_cb_cancel_data * match,struct io_wq_work * work)1030 static bool __io_wq_worker_cancel(struct io_worker *worker,
1031 struct io_cb_cancel_data *match,
1032 struct io_wq_work *work)
1033 {
1034 if (work && match->fn(work, match->data)) {
1035 atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
1036 __set_notify_signal(worker->task);
1037 return true;
1038 }
1039
1040 return false;
1041 }
1042
io_wq_worker_cancel(struct io_worker * worker,void * data)1043 static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
1044 {
1045 struct io_cb_cancel_data *match = data;
1046
1047 /*
1048 * Hold the lock to avoid ->cur_work going out of scope, caller
1049 * may dereference the passed in work.
1050 */
1051 raw_spin_lock(&worker->lock);
1052 if (__io_wq_worker_cancel(worker, match, worker->cur_work))
1053 match->nr_running++;
1054 raw_spin_unlock(&worker->lock);
1055
1056 return match->nr_running && !match->cancel_all;
1057 }
1058
io_wq_remove_pending(struct io_wq * wq,struct io_wq_acct * acct,struct io_wq_work * work,struct io_wq_work_node * prev)1059 static inline void io_wq_remove_pending(struct io_wq *wq,
1060 struct io_wq_acct *acct,
1061 struct io_wq_work *work,
1062 struct io_wq_work_node *prev)
1063 {
1064 unsigned int hash = io_get_work_hash(work);
1065 struct io_wq_work *prev_work = NULL;
1066
1067 if (io_wq_is_hashed(work) && work == wq->hash_tail[hash]) {
1068 if (prev)
1069 prev_work = container_of(prev, struct io_wq_work, list);
1070 if (prev_work && io_get_work_hash(prev_work) == hash)
1071 wq->hash_tail[hash] = prev_work;
1072 else
1073 wq->hash_tail[hash] = NULL;
1074 }
1075 wq_list_del(&acct->work_list, &work->list, prev);
1076 }
1077
io_acct_cancel_pending_work(struct io_wq * wq,struct io_wq_acct * acct,struct io_cb_cancel_data * match)1078 static bool io_acct_cancel_pending_work(struct io_wq *wq,
1079 struct io_wq_acct *acct,
1080 struct io_cb_cancel_data *match)
1081 {
1082 struct io_wq_work_node *node, *prev;
1083 struct io_wq_work *work;
1084
1085 raw_spin_lock(&acct->lock);
1086 wq_list_for_each(node, prev, &acct->work_list) {
1087 work = container_of(node, struct io_wq_work, list);
1088 if (!match->fn(work, match->data))
1089 continue;
1090 io_wq_remove_pending(wq, acct, work, prev);
1091 raw_spin_unlock(&acct->lock);
1092 io_run_cancel(work, wq);
1093 match->nr_pending++;
1094 /* not safe to continue after unlock */
1095 return true;
1096 }
1097 raw_spin_unlock(&acct->lock);
1098
1099 return false;
1100 }
1101
io_wq_cancel_pending_work(struct io_wq * wq,struct io_cb_cancel_data * match)1102 static void io_wq_cancel_pending_work(struct io_wq *wq,
1103 struct io_cb_cancel_data *match)
1104 {
1105 int i;
1106 retry:
1107 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1108 struct io_wq_acct *acct = io_get_acct(wq, i == 0);
1109
1110 if (io_acct_cancel_pending_work(wq, acct, match)) {
1111 if (match->cancel_all)
1112 goto retry;
1113 break;
1114 }
1115 }
1116 }
1117
io_acct_cancel_running_work(struct io_wq_acct * acct,struct io_cb_cancel_data * match)1118 static void io_acct_cancel_running_work(struct io_wq_acct *acct,
1119 struct io_cb_cancel_data *match)
1120 {
1121 raw_spin_lock(&acct->workers_lock);
1122 io_acct_for_each_worker(acct, io_wq_worker_cancel, match);
1123 raw_spin_unlock(&acct->workers_lock);
1124 }
1125
io_wq_cancel_running_work(struct io_wq * wq,struct io_cb_cancel_data * match)1126 static void io_wq_cancel_running_work(struct io_wq *wq,
1127 struct io_cb_cancel_data *match)
1128 {
1129 rcu_read_lock();
1130
1131 for (int i = 0; i < IO_WQ_ACCT_NR; i++)
1132 io_acct_cancel_running_work(&wq->acct[i], match);
1133
1134 rcu_read_unlock();
1135 }
1136
io_wq_cancel_cb(struct io_wq * wq,work_cancel_fn * cancel,void * data,bool cancel_all)1137 enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
1138 void *data, bool cancel_all)
1139 {
1140 struct io_cb_cancel_data match = {
1141 .fn = cancel,
1142 .data = data,
1143 .cancel_all = cancel_all,
1144 };
1145
1146 /*
1147 * First check pending list, if we're lucky we can just remove it
1148 * from there. CANCEL_OK means that the work is returned as-new,
1149 * no completion will be posted for it.
1150 *
1151 * Then check if a free (going busy) or busy worker has the work
1152 * currently running. If we find it there, we'll return CANCEL_RUNNING
1153 * as an indication that we attempt to signal cancellation. The
1154 * completion will run normally in this case.
1155 *
1156 * Do both of these while holding the acct->workers_lock, to ensure that
1157 * we'll find a work item regardless of state.
1158 */
1159 io_wq_cancel_pending_work(wq, &match);
1160 if (match.nr_pending && !match.cancel_all)
1161 return IO_WQ_CANCEL_OK;
1162
1163 io_wq_cancel_running_work(wq, &match);
1164 if (match.nr_running && !match.cancel_all)
1165 return IO_WQ_CANCEL_RUNNING;
1166
1167 if (match.nr_running)
1168 return IO_WQ_CANCEL_RUNNING;
1169 if (match.nr_pending)
1170 return IO_WQ_CANCEL_OK;
1171 return IO_WQ_CANCEL_NOTFOUND;
1172 }
1173
io_wq_hash_wake(struct wait_queue_entry * wait,unsigned mode,int sync,void * key)1174 static int io_wq_hash_wake(struct wait_queue_entry *wait, unsigned mode,
1175 int sync, void *key)
1176 {
1177 struct io_wq *wq = container_of(wait, struct io_wq, wait);
1178 int i;
1179
1180 list_del_init(&wait->entry);
1181
1182 rcu_read_lock();
1183 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1184 struct io_wq_acct *acct = &wq->acct[i];
1185
1186 if (test_and_clear_bit(IO_ACCT_STALLED_BIT, &acct->flags))
1187 io_acct_activate_free_worker(acct);
1188 }
1189 rcu_read_unlock();
1190 return 1;
1191 }
1192
io_wq_create(unsigned bounded,struct io_wq_data * data)1193 struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
1194 {
1195 int ret, i;
1196 struct io_wq *wq;
1197
1198 if (WARN_ON_ONCE(!data->free_work || !data->do_work))
1199 return ERR_PTR(-EINVAL);
1200 if (WARN_ON_ONCE(!bounded))
1201 return ERR_PTR(-EINVAL);
1202
1203 wq = kzalloc(sizeof(struct io_wq), GFP_KERNEL);
1204 if (!wq)
1205 return ERR_PTR(-ENOMEM);
1206
1207 refcount_inc(&data->hash->refs);
1208 wq->hash = data->hash;
1209 wq->free_work = data->free_work;
1210 wq->do_work = data->do_work;
1211
1212 ret = -ENOMEM;
1213
1214 if (!alloc_cpumask_var(&wq->cpu_mask, GFP_KERNEL))
1215 goto err;
1216 cpuset_cpus_allowed(data->task, wq->cpu_mask);
1217 wq->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
1218 wq->acct[IO_WQ_ACCT_UNBOUND].max_workers =
1219 task_rlimit(current, RLIMIT_NPROC);
1220 INIT_LIST_HEAD(&wq->wait.entry);
1221 wq->wait.func = io_wq_hash_wake;
1222 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1223 struct io_wq_acct *acct = &wq->acct[i];
1224
1225 atomic_set(&acct->nr_running, 0);
1226
1227 raw_spin_lock_init(&acct->workers_lock);
1228 INIT_HLIST_NULLS_HEAD(&acct->free_list, 0);
1229 INIT_LIST_HEAD(&acct->all_list);
1230
1231 INIT_WQ_LIST(&acct->work_list);
1232 raw_spin_lock_init(&acct->lock);
1233 }
1234
1235 wq->task = get_task_struct(data->task);
1236 atomic_set(&wq->worker_refs, 1);
1237 init_completion(&wq->worker_done);
1238 ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1239 if (ret)
1240 goto err;
1241
1242 return wq;
1243 err:
1244 io_wq_put_hash(data->hash);
1245 free_cpumask_var(wq->cpu_mask);
1246 kfree(wq);
1247 return ERR_PTR(ret);
1248 }
1249
io_task_work_match(struct callback_head * cb,void * data)1250 static bool io_task_work_match(struct callback_head *cb, void *data)
1251 {
1252 struct io_worker *worker;
1253
1254 if (cb->func != create_worker_cb && cb->func != create_worker_cont)
1255 return false;
1256 worker = container_of(cb, struct io_worker, create_work);
1257 return worker->wq == data;
1258 }
1259
io_wq_exit_start(struct io_wq * wq)1260 void io_wq_exit_start(struct io_wq *wq)
1261 {
1262 set_bit(IO_WQ_BIT_EXIT, &wq->state);
1263 }
1264
io_wq_cancel_tw_create(struct io_wq * wq)1265 static void io_wq_cancel_tw_create(struct io_wq *wq)
1266 {
1267 struct callback_head *cb;
1268
1269 while ((cb = task_work_cancel_match(wq->task, io_task_work_match, wq)) != NULL) {
1270 struct io_worker *worker;
1271
1272 worker = container_of(cb, struct io_worker, create_work);
1273 io_worker_cancel_cb(worker);
1274 /*
1275 * Only the worker continuation helper has worker allocated and
1276 * hence needs freeing.
1277 */
1278 if (cb->func == create_worker_cont)
1279 kfree(worker);
1280 }
1281 }
1282
io_wq_exit_workers(struct io_wq * wq)1283 static void io_wq_exit_workers(struct io_wq *wq)
1284 {
1285 if (!wq->task)
1286 return;
1287
1288 io_wq_cancel_tw_create(wq);
1289
1290 rcu_read_lock();
1291 io_wq_for_each_worker(wq, io_wq_worker_wake, NULL);
1292 rcu_read_unlock();
1293 io_worker_ref_put(wq);
1294 wait_for_completion(&wq->worker_done);
1295
1296 spin_lock_irq(&wq->hash->wait.lock);
1297 list_del_init(&wq->wait.entry);
1298 spin_unlock_irq(&wq->hash->wait.lock);
1299
1300 put_task_struct(wq->task);
1301 wq->task = NULL;
1302 }
1303
io_wq_destroy(struct io_wq * wq)1304 static void io_wq_destroy(struct io_wq *wq)
1305 {
1306 struct io_cb_cancel_data match = {
1307 .fn = io_wq_work_match_all,
1308 .cancel_all = true,
1309 };
1310
1311 cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
1312 io_wq_cancel_pending_work(wq, &match);
1313 free_cpumask_var(wq->cpu_mask);
1314 io_wq_put_hash(wq->hash);
1315 kfree(wq);
1316 }
1317
io_wq_put_and_exit(struct io_wq * wq)1318 void io_wq_put_and_exit(struct io_wq *wq)
1319 {
1320 WARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, &wq->state));
1321
1322 io_wq_exit_workers(wq);
1323 io_wq_destroy(wq);
1324 }
1325
1326 struct online_data {
1327 unsigned int cpu;
1328 bool online;
1329 };
1330
io_wq_worker_affinity(struct io_worker * worker,void * data)1331 static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
1332 {
1333 struct online_data *od = data;
1334
1335 if (od->online)
1336 cpumask_set_cpu(od->cpu, worker->wq->cpu_mask);
1337 else
1338 cpumask_clear_cpu(od->cpu, worker->wq->cpu_mask);
1339 return false;
1340 }
1341
__io_wq_cpu_online(struct io_wq * wq,unsigned int cpu,bool online)1342 static int __io_wq_cpu_online(struct io_wq *wq, unsigned int cpu, bool online)
1343 {
1344 struct online_data od = {
1345 .cpu = cpu,
1346 .online = online
1347 };
1348
1349 rcu_read_lock();
1350 io_wq_for_each_worker(wq, io_wq_worker_affinity, &od);
1351 rcu_read_unlock();
1352 return 0;
1353 }
1354
io_wq_cpu_online(unsigned int cpu,struct hlist_node * node)1355 static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
1356 {
1357 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1358
1359 return __io_wq_cpu_online(wq, cpu, true);
1360 }
1361
io_wq_cpu_offline(unsigned int cpu,struct hlist_node * node)1362 static int io_wq_cpu_offline(unsigned int cpu, struct hlist_node *node)
1363 {
1364 struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
1365
1366 return __io_wq_cpu_online(wq, cpu, false);
1367 }
1368
io_wq_cpu_affinity(struct io_uring_task * tctx,cpumask_var_t mask)1369 int io_wq_cpu_affinity(struct io_uring_task *tctx, cpumask_var_t mask)
1370 {
1371 cpumask_var_t allowed_mask;
1372 int ret = 0;
1373
1374 if (!tctx || !tctx->io_wq)
1375 return -EINVAL;
1376
1377 if (!alloc_cpumask_var(&allowed_mask, GFP_KERNEL))
1378 return -ENOMEM;
1379
1380 rcu_read_lock();
1381 cpuset_cpus_allowed(tctx->io_wq->task, allowed_mask);
1382 if (mask) {
1383 if (cpumask_subset(mask, allowed_mask))
1384 cpumask_copy(tctx->io_wq->cpu_mask, mask);
1385 else
1386 ret = -EINVAL;
1387 } else {
1388 cpumask_copy(tctx->io_wq->cpu_mask, allowed_mask);
1389 }
1390 rcu_read_unlock();
1391
1392 free_cpumask_var(allowed_mask);
1393 return ret;
1394 }
1395
1396 /*
1397 * Set max number of unbounded workers, returns old value. If new_count is 0,
1398 * then just return the old value.
1399 */
io_wq_max_workers(struct io_wq * wq,int * new_count)1400 int io_wq_max_workers(struct io_wq *wq, int *new_count)
1401 {
1402 struct io_wq_acct *acct;
1403 int prev[IO_WQ_ACCT_NR];
1404 int i;
1405
1406 BUILD_BUG_ON((int) IO_WQ_ACCT_BOUND != (int) IO_WQ_BOUND);
1407 BUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND);
1408 BUILD_BUG_ON((int) IO_WQ_ACCT_NR != 2);
1409
1410 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1411 if (new_count[i] > task_rlimit(current, RLIMIT_NPROC))
1412 new_count[i] = task_rlimit(current, RLIMIT_NPROC);
1413 }
1414
1415 for (i = 0; i < IO_WQ_ACCT_NR; i++)
1416 prev[i] = 0;
1417
1418 rcu_read_lock();
1419
1420 for (i = 0; i < IO_WQ_ACCT_NR; i++) {
1421 acct = &wq->acct[i];
1422 raw_spin_lock(&acct->workers_lock);
1423 prev[i] = max_t(int, acct->max_workers, prev[i]);
1424 if (new_count[i])
1425 acct->max_workers = new_count[i];
1426 raw_spin_unlock(&acct->workers_lock);
1427 }
1428 rcu_read_unlock();
1429
1430 for (i = 0; i < IO_WQ_ACCT_NR; i++)
1431 new_count[i] = prev[i];
1432
1433 return 0;
1434 }
1435
io_wq_init(void)1436 static __init int io_wq_init(void)
1437 {
1438 int ret;
1439
1440 ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "io-wq/online",
1441 io_wq_cpu_online, io_wq_cpu_offline);
1442 if (ret < 0)
1443 return ret;
1444 io_wq_online = ret;
1445 return 0;
1446 }
1447 subsys_initcall(io_wq_init);
1448