xref: /linux/io_uring/io-wq.c (revision 91928e0d3cc29789f4483bffee5f36218f23942b)
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