xref: /openbmc/linux/io_uring/timeout.c (revision 6fa24b41)
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/kernel.h>
3 #include <linux/errno.h>
4 #include <linux/file.h>
5 #include <linux/io_uring.h>
6 
7 #include <trace/events/io_uring.h>
8 
9 #include <uapi/linux/io_uring.h>
10 
11 #include "io_uring.h"
12 #include "refs.h"
13 #include "cancel.h"
14 #include "timeout.h"
15 
16 struct io_timeout {
17 	struct file			*file;
18 	u32				off;
19 	u32				target_seq;
20 	u32				repeats;
21 	struct list_head		list;
22 	/* head of the link, used by linked timeouts only */
23 	struct io_kiocb			*head;
24 	/* for linked completions */
25 	struct io_kiocb			*prev;
26 };
27 
28 struct io_timeout_rem {
29 	struct file			*file;
30 	u64				addr;
31 
32 	/* timeout update */
33 	struct timespec64		ts;
34 	u32				flags;
35 	bool				ltimeout;
36 };
37 
38 static inline bool io_is_timeout_noseq(struct io_kiocb *req)
39 {
40 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
41 	struct io_timeout_data *data = req->async_data;
42 
43 	return !timeout->off || data->flags & IORING_TIMEOUT_MULTISHOT;
44 }
45 
46 static inline void io_put_req(struct io_kiocb *req)
47 {
48 	if (req_ref_put_and_test(req)) {
49 		io_queue_next(req);
50 		io_free_req(req);
51 	}
52 }
53 
54 static inline bool io_timeout_finish(struct io_timeout *timeout,
55 				     struct io_timeout_data *data)
56 {
57 	if (!(data->flags & IORING_TIMEOUT_MULTISHOT))
58 		return true;
59 
60 	if (!timeout->off || (timeout->repeats && --timeout->repeats))
61 		return false;
62 
63 	return true;
64 }
65 
66 static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer);
67 
68 static void io_timeout_complete(struct io_kiocb *req, struct io_tw_state *ts)
69 {
70 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
71 	struct io_timeout_data *data = req->async_data;
72 	struct io_ring_ctx *ctx = req->ctx;
73 
74 	if (!io_timeout_finish(timeout, data)) {
75 		bool filled;
76 		filled = io_fill_cqe_req_aux(req, ts->locked, -ETIME,
77 					     IORING_CQE_F_MORE);
78 		if (filled) {
79 			/* re-arm timer */
80 			spin_lock_irq(&ctx->timeout_lock);
81 			list_add(&timeout->list, ctx->timeout_list.prev);
82 			data->timer.function = io_timeout_fn;
83 			hrtimer_start(&data->timer, timespec64_to_ktime(data->ts), data->mode);
84 			spin_unlock_irq(&ctx->timeout_lock);
85 			return;
86 		}
87 	}
88 
89 	io_req_task_complete(req, ts);
90 }
91 
92 static bool io_kill_timeout(struct io_kiocb *req, int status)
93 	__must_hold(&req->ctx->timeout_lock)
94 {
95 	struct io_timeout_data *io = req->async_data;
96 
97 	if (hrtimer_try_to_cancel(&io->timer) != -1) {
98 		struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
99 
100 		if (status)
101 			req_set_fail(req);
102 		atomic_set(&req->ctx->cq_timeouts,
103 			atomic_read(&req->ctx->cq_timeouts) + 1);
104 		list_del_init(&timeout->list);
105 		io_req_queue_tw_complete(req, status);
106 		return true;
107 	}
108 	return false;
109 }
110 
111 __cold void io_flush_timeouts(struct io_ring_ctx *ctx)
112 {
113 	u32 seq;
114 	struct io_timeout *timeout, *tmp;
115 
116 	spin_lock_irq(&ctx->timeout_lock);
117 	seq = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
118 
119 	list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {
120 		struct io_kiocb *req = cmd_to_io_kiocb(timeout);
121 		u32 events_needed, events_got;
122 
123 		if (io_is_timeout_noseq(req))
124 			break;
125 
126 		/*
127 		 * Since seq can easily wrap around over time, subtract
128 		 * the last seq at which timeouts were flushed before comparing.
129 		 * Assuming not more than 2^31-1 events have happened since,
130 		 * these subtractions won't have wrapped, so we can check if
131 		 * target is in [last_seq, current_seq] by comparing the two.
132 		 */
133 		events_needed = timeout->target_seq - ctx->cq_last_tm_flush;
134 		events_got = seq - ctx->cq_last_tm_flush;
135 		if (events_got < events_needed)
136 			break;
137 
138 		io_kill_timeout(req, 0);
139 	}
140 	ctx->cq_last_tm_flush = seq;
141 	spin_unlock_irq(&ctx->timeout_lock);
142 }
143 
144 static void io_req_tw_fail_links(struct io_kiocb *link, struct io_tw_state *ts)
145 {
146 	io_tw_lock(link->ctx, ts);
147 	while (link) {
148 		struct io_kiocb *nxt = link->link;
149 		long res = -ECANCELED;
150 
151 		if (link->flags & REQ_F_FAIL)
152 			res = link->cqe.res;
153 		link->link = NULL;
154 		io_req_set_res(link, res, 0);
155 		io_req_task_complete(link, ts);
156 		link = nxt;
157 	}
158 }
159 
160 static void io_fail_links(struct io_kiocb *req)
161 	__must_hold(&req->ctx->completion_lock)
162 {
163 	struct io_kiocb *link = req->link;
164 	bool ignore_cqes = req->flags & REQ_F_SKIP_LINK_CQES;
165 
166 	if (!link)
167 		return;
168 
169 	while (link) {
170 		if (ignore_cqes)
171 			link->flags |= REQ_F_CQE_SKIP;
172 		else
173 			link->flags &= ~REQ_F_CQE_SKIP;
174 		trace_io_uring_fail_link(req, link);
175 		link = link->link;
176 	}
177 
178 	link = req->link;
179 	link->io_task_work.func = io_req_tw_fail_links;
180 	io_req_task_work_add(link);
181 	req->link = NULL;
182 }
183 
184 static inline void io_remove_next_linked(struct io_kiocb *req)
185 {
186 	struct io_kiocb *nxt = req->link;
187 
188 	req->link = nxt->link;
189 	nxt->link = NULL;
190 }
191 
192 void io_disarm_next(struct io_kiocb *req)
193 	__must_hold(&req->ctx->completion_lock)
194 {
195 	struct io_kiocb *link = NULL;
196 
197 	if (req->flags & REQ_F_ARM_LTIMEOUT) {
198 		link = req->link;
199 		req->flags &= ~REQ_F_ARM_LTIMEOUT;
200 		if (link && link->opcode == IORING_OP_LINK_TIMEOUT) {
201 			io_remove_next_linked(req);
202 			io_req_queue_tw_complete(link, -ECANCELED);
203 		}
204 	} else if (req->flags & REQ_F_LINK_TIMEOUT) {
205 		struct io_ring_ctx *ctx = req->ctx;
206 
207 		spin_lock_irq(&ctx->timeout_lock);
208 		link = io_disarm_linked_timeout(req);
209 		spin_unlock_irq(&ctx->timeout_lock);
210 		if (link)
211 			io_req_queue_tw_complete(link, -ECANCELED);
212 	}
213 	if (unlikely((req->flags & REQ_F_FAIL) &&
214 		     !(req->flags & REQ_F_HARDLINK)))
215 		io_fail_links(req);
216 }
217 
218 struct io_kiocb *__io_disarm_linked_timeout(struct io_kiocb *req,
219 					    struct io_kiocb *link)
220 	__must_hold(&req->ctx->completion_lock)
221 	__must_hold(&req->ctx->timeout_lock)
222 {
223 	struct io_timeout_data *io = link->async_data;
224 	struct io_timeout *timeout = io_kiocb_to_cmd(link, struct io_timeout);
225 
226 	io_remove_next_linked(req);
227 	timeout->head = NULL;
228 	if (hrtimer_try_to_cancel(&io->timer) != -1) {
229 		list_del(&timeout->list);
230 		return link;
231 	}
232 
233 	return NULL;
234 }
235 
236 static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
237 {
238 	struct io_timeout_data *data = container_of(timer,
239 						struct io_timeout_data, timer);
240 	struct io_kiocb *req = data->req;
241 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
242 	struct io_ring_ctx *ctx = req->ctx;
243 	unsigned long flags;
244 
245 	spin_lock_irqsave(&ctx->timeout_lock, flags);
246 	list_del_init(&timeout->list);
247 	atomic_set(&req->ctx->cq_timeouts,
248 		atomic_read(&req->ctx->cq_timeouts) + 1);
249 	spin_unlock_irqrestore(&ctx->timeout_lock, flags);
250 
251 	if (!(data->flags & IORING_TIMEOUT_ETIME_SUCCESS))
252 		req_set_fail(req);
253 
254 	io_req_set_res(req, -ETIME, 0);
255 	req->io_task_work.func = io_timeout_complete;
256 	io_req_task_work_add(req);
257 	return HRTIMER_NORESTART;
258 }
259 
260 static struct io_kiocb *io_timeout_extract(struct io_ring_ctx *ctx,
261 					   struct io_cancel_data *cd)
262 	__must_hold(&ctx->timeout_lock)
263 {
264 	struct io_timeout *timeout;
265 	struct io_timeout_data *io;
266 	struct io_kiocb *req = NULL;
267 
268 	list_for_each_entry(timeout, &ctx->timeout_list, list) {
269 		struct io_kiocb *tmp = cmd_to_io_kiocb(timeout);
270 
271 		if (io_cancel_req_match(tmp, cd)) {
272 			req = tmp;
273 			break;
274 		}
275 	}
276 	if (!req)
277 		return ERR_PTR(-ENOENT);
278 
279 	io = req->async_data;
280 	if (hrtimer_try_to_cancel(&io->timer) == -1)
281 		return ERR_PTR(-EALREADY);
282 	timeout = io_kiocb_to_cmd(req, struct io_timeout);
283 	list_del_init(&timeout->list);
284 	return req;
285 }
286 
287 int io_timeout_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
288 	__must_hold(&ctx->completion_lock)
289 {
290 	struct io_kiocb *req;
291 
292 	spin_lock_irq(&ctx->timeout_lock);
293 	req = io_timeout_extract(ctx, cd);
294 	spin_unlock_irq(&ctx->timeout_lock);
295 
296 	if (IS_ERR(req))
297 		return PTR_ERR(req);
298 	io_req_task_queue_fail(req, -ECANCELED);
299 	return 0;
300 }
301 
302 static void io_req_task_link_timeout(struct io_kiocb *req, struct io_tw_state *ts)
303 {
304 	unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED;
305 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
306 	struct io_kiocb *prev = timeout->prev;
307 	int ret = -ENOENT;
308 
309 	if (prev) {
310 		if (!(req->task->flags & PF_EXITING)) {
311 			struct io_cancel_data cd = {
312 				.ctx		= req->ctx,
313 				.data		= prev->cqe.user_data,
314 			};
315 
316 			ret = io_try_cancel(req->task->io_uring, &cd, issue_flags);
317 		}
318 		io_req_set_res(req, ret ?: -ETIME, 0);
319 		io_req_task_complete(req, ts);
320 		io_put_req(prev);
321 	} else {
322 		io_req_set_res(req, -ETIME, 0);
323 		io_req_task_complete(req, ts);
324 	}
325 }
326 
327 static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
328 {
329 	struct io_timeout_data *data = container_of(timer,
330 						struct io_timeout_data, timer);
331 	struct io_kiocb *prev, *req = data->req;
332 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
333 	struct io_ring_ctx *ctx = req->ctx;
334 	unsigned long flags;
335 
336 	spin_lock_irqsave(&ctx->timeout_lock, flags);
337 	prev = timeout->head;
338 	timeout->head = NULL;
339 
340 	/*
341 	 * We don't expect the list to be empty, that will only happen if we
342 	 * race with the completion of the linked work.
343 	 */
344 	if (prev) {
345 		io_remove_next_linked(prev);
346 		if (!req_ref_inc_not_zero(prev))
347 			prev = NULL;
348 	}
349 	list_del(&timeout->list);
350 	timeout->prev = prev;
351 	spin_unlock_irqrestore(&ctx->timeout_lock, flags);
352 
353 	req->io_task_work.func = io_req_task_link_timeout;
354 	io_req_task_work_add(req);
355 	return HRTIMER_NORESTART;
356 }
357 
358 static clockid_t io_timeout_get_clock(struct io_timeout_data *data)
359 {
360 	switch (data->flags & IORING_TIMEOUT_CLOCK_MASK) {
361 	case IORING_TIMEOUT_BOOTTIME:
362 		return CLOCK_BOOTTIME;
363 	case IORING_TIMEOUT_REALTIME:
364 		return CLOCK_REALTIME;
365 	default:
366 		/* can't happen, vetted at prep time */
367 		WARN_ON_ONCE(1);
368 		fallthrough;
369 	case 0:
370 		return CLOCK_MONOTONIC;
371 	}
372 }
373 
374 static int io_linked_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
375 				    struct timespec64 *ts, enum hrtimer_mode mode)
376 	__must_hold(&ctx->timeout_lock)
377 {
378 	struct io_timeout_data *io;
379 	struct io_timeout *timeout;
380 	struct io_kiocb *req = NULL;
381 
382 	list_for_each_entry(timeout, &ctx->ltimeout_list, list) {
383 		struct io_kiocb *tmp = cmd_to_io_kiocb(timeout);
384 
385 		if (user_data == tmp->cqe.user_data) {
386 			req = tmp;
387 			break;
388 		}
389 	}
390 	if (!req)
391 		return -ENOENT;
392 
393 	io = req->async_data;
394 	if (hrtimer_try_to_cancel(&io->timer) == -1)
395 		return -EALREADY;
396 	hrtimer_init(&io->timer, io_timeout_get_clock(io), mode);
397 	io->timer.function = io_link_timeout_fn;
398 	hrtimer_start(&io->timer, timespec64_to_ktime(*ts), mode);
399 	return 0;
400 }
401 
402 static int io_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
403 			     struct timespec64 *ts, enum hrtimer_mode mode)
404 	__must_hold(&ctx->timeout_lock)
405 {
406 	struct io_cancel_data cd = { .ctx = ctx, .data = user_data, };
407 	struct io_kiocb *req = io_timeout_extract(ctx, &cd);
408 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
409 	struct io_timeout_data *data;
410 
411 	if (IS_ERR(req))
412 		return PTR_ERR(req);
413 
414 	timeout->off = 0; /* noseq */
415 	data = req->async_data;
416 	list_add_tail(&timeout->list, &ctx->timeout_list);
417 	hrtimer_init(&data->timer, io_timeout_get_clock(data), mode);
418 	data->timer.function = io_timeout_fn;
419 	hrtimer_start(&data->timer, timespec64_to_ktime(*ts), mode);
420 	return 0;
421 }
422 
423 int io_timeout_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
424 {
425 	struct io_timeout_rem *tr = io_kiocb_to_cmd(req, struct io_timeout_rem);
426 
427 	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
428 		return -EINVAL;
429 	if (sqe->buf_index || sqe->len || sqe->splice_fd_in)
430 		return -EINVAL;
431 
432 	tr->ltimeout = false;
433 	tr->addr = READ_ONCE(sqe->addr);
434 	tr->flags = READ_ONCE(sqe->timeout_flags);
435 	if (tr->flags & IORING_TIMEOUT_UPDATE_MASK) {
436 		if (hweight32(tr->flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
437 			return -EINVAL;
438 		if (tr->flags & IORING_LINK_TIMEOUT_UPDATE)
439 			tr->ltimeout = true;
440 		if (tr->flags & ~(IORING_TIMEOUT_UPDATE_MASK|IORING_TIMEOUT_ABS))
441 			return -EINVAL;
442 		if (get_timespec64(&tr->ts, u64_to_user_ptr(sqe->addr2)))
443 			return -EFAULT;
444 		if (tr->ts.tv_sec < 0 || tr->ts.tv_nsec < 0)
445 			return -EINVAL;
446 	} else if (tr->flags) {
447 		/* timeout removal doesn't support flags */
448 		return -EINVAL;
449 	}
450 
451 	return 0;
452 }
453 
454 static inline enum hrtimer_mode io_translate_timeout_mode(unsigned int flags)
455 {
456 	return (flags & IORING_TIMEOUT_ABS) ? HRTIMER_MODE_ABS
457 					    : HRTIMER_MODE_REL;
458 }
459 
460 /*
461  * Remove or update an existing timeout command
462  */
463 int io_timeout_remove(struct io_kiocb *req, unsigned int issue_flags)
464 {
465 	struct io_timeout_rem *tr = io_kiocb_to_cmd(req, struct io_timeout_rem);
466 	struct io_ring_ctx *ctx = req->ctx;
467 	int ret;
468 
469 	if (!(tr->flags & IORING_TIMEOUT_UPDATE)) {
470 		struct io_cancel_data cd = { .ctx = ctx, .data = tr->addr, };
471 
472 		spin_lock(&ctx->completion_lock);
473 		ret = io_timeout_cancel(ctx, &cd);
474 		spin_unlock(&ctx->completion_lock);
475 	} else {
476 		enum hrtimer_mode mode = io_translate_timeout_mode(tr->flags);
477 
478 		spin_lock_irq(&ctx->timeout_lock);
479 		if (tr->ltimeout)
480 			ret = io_linked_timeout_update(ctx, tr->addr, &tr->ts, mode);
481 		else
482 			ret = io_timeout_update(ctx, tr->addr, &tr->ts, mode);
483 		spin_unlock_irq(&ctx->timeout_lock);
484 	}
485 
486 	if (ret < 0)
487 		req_set_fail(req);
488 	io_req_set_res(req, ret, 0);
489 	return IOU_OK;
490 }
491 
492 static int __io_timeout_prep(struct io_kiocb *req,
493 			     const struct io_uring_sqe *sqe,
494 			     bool is_timeout_link)
495 {
496 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
497 	struct io_timeout_data *data;
498 	unsigned flags;
499 	u32 off = READ_ONCE(sqe->off);
500 
501 	if (sqe->buf_index || sqe->len != 1 || sqe->splice_fd_in)
502 		return -EINVAL;
503 	if (off && is_timeout_link)
504 		return -EINVAL;
505 	flags = READ_ONCE(sqe->timeout_flags);
506 	if (flags & ~(IORING_TIMEOUT_ABS | IORING_TIMEOUT_CLOCK_MASK |
507 		      IORING_TIMEOUT_ETIME_SUCCESS |
508 		      IORING_TIMEOUT_MULTISHOT))
509 		return -EINVAL;
510 	/* more than one clock specified is invalid, obviously */
511 	if (hweight32(flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
512 		return -EINVAL;
513 	/* multishot requests only make sense with rel values */
514 	if (!(~flags & (IORING_TIMEOUT_MULTISHOT | IORING_TIMEOUT_ABS)))
515 		return -EINVAL;
516 
517 	INIT_LIST_HEAD(&timeout->list);
518 	timeout->off = off;
519 	if (unlikely(off && !req->ctx->off_timeout_used))
520 		req->ctx->off_timeout_used = true;
521 	/*
522 	 * for multishot reqs w/ fixed nr of repeats, repeats tracks the
523 	 * remaining nr
524 	 */
525 	timeout->repeats = 0;
526 	if ((flags & IORING_TIMEOUT_MULTISHOT) && off > 0)
527 		timeout->repeats = off;
528 
529 	if (WARN_ON_ONCE(req_has_async_data(req)))
530 		return -EFAULT;
531 	if (io_alloc_async_data(req))
532 		return -ENOMEM;
533 
534 	data = req->async_data;
535 	data->req = req;
536 	data->flags = flags;
537 
538 	if (get_timespec64(&data->ts, u64_to_user_ptr(sqe->addr)))
539 		return -EFAULT;
540 
541 	if (data->ts.tv_sec < 0 || data->ts.tv_nsec < 0)
542 		return -EINVAL;
543 
544 	INIT_LIST_HEAD(&timeout->list);
545 	data->mode = io_translate_timeout_mode(flags);
546 	hrtimer_init(&data->timer, io_timeout_get_clock(data), data->mode);
547 
548 	if (is_timeout_link) {
549 		struct io_submit_link *link = &req->ctx->submit_state.link;
550 
551 		if (!link->head)
552 			return -EINVAL;
553 		if (link->last->opcode == IORING_OP_LINK_TIMEOUT)
554 			return -EINVAL;
555 		timeout->head = link->last;
556 		link->last->flags |= REQ_F_ARM_LTIMEOUT;
557 	}
558 	return 0;
559 }
560 
561 int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
562 {
563 	return __io_timeout_prep(req, sqe, false);
564 }
565 
566 int io_link_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
567 {
568 	return __io_timeout_prep(req, sqe, true);
569 }
570 
571 int io_timeout(struct io_kiocb *req, unsigned int issue_flags)
572 {
573 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
574 	struct io_ring_ctx *ctx = req->ctx;
575 	struct io_timeout_data *data = req->async_data;
576 	struct list_head *entry;
577 	u32 tail, off = timeout->off;
578 
579 	spin_lock_irq(&ctx->timeout_lock);
580 
581 	/*
582 	 * sqe->off holds how many events that need to occur for this
583 	 * timeout event to be satisfied. If it isn't set, then this is
584 	 * a pure timeout request, sequence isn't used.
585 	 */
586 	if (io_is_timeout_noseq(req)) {
587 		entry = ctx->timeout_list.prev;
588 		goto add;
589 	}
590 
591 	tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts);
592 	timeout->target_seq = tail + off;
593 
594 	/* Update the last seq here in case io_flush_timeouts() hasn't.
595 	 * This is safe because ->completion_lock is held, and submissions
596 	 * and completions are never mixed in the same ->completion_lock section.
597 	 */
598 	ctx->cq_last_tm_flush = tail;
599 
600 	/*
601 	 * Insertion sort, ensuring the first entry in the list is always
602 	 * the one we need first.
603 	 */
604 	list_for_each_prev(entry, &ctx->timeout_list) {
605 		struct io_timeout *nextt = list_entry(entry, struct io_timeout, list);
606 		struct io_kiocb *nxt = cmd_to_io_kiocb(nextt);
607 
608 		if (io_is_timeout_noseq(nxt))
609 			continue;
610 		/* nxt.seq is behind @tail, otherwise would've been completed */
611 		if (off >= nextt->target_seq - tail)
612 			break;
613 	}
614 add:
615 	list_add(&timeout->list, entry);
616 	data->timer.function = io_timeout_fn;
617 	hrtimer_start(&data->timer, timespec64_to_ktime(data->ts), data->mode);
618 	spin_unlock_irq(&ctx->timeout_lock);
619 	return IOU_ISSUE_SKIP_COMPLETE;
620 }
621 
622 void io_queue_linked_timeout(struct io_kiocb *req)
623 {
624 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
625 	struct io_ring_ctx *ctx = req->ctx;
626 
627 	spin_lock_irq(&ctx->timeout_lock);
628 	/*
629 	 * If the back reference is NULL, then our linked request finished
630 	 * before we got a chance to setup the timer
631 	 */
632 	if (timeout->head) {
633 		struct io_timeout_data *data = req->async_data;
634 
635 		data->timer.function = io_link_timeout_fn;
636 		hrtimer_start(&data->timer, timespec64_to_ktime(data->ts),
637 				data->mode);
638 		list_add_tail(&timeout->list, &ctx->ltimeout_list);
639 	}
640 	spin_unlock_irq(&ctx->timeout_lock);
641 	/* drop submission reference */
642 	io_put_req(req);
643 }
644 
645 static bool io_match_task(struct io_kiocb *head, struct task_struct *task,
646 			  bool cancel_all)
647 	__must_hold(&head->ctx->timeout_lock)
648 {
649 	struct io_kiocb *req;
650 
651 	if (task && head->task != task)
652 		return false;
653 	if (cancel_all)
654 		return true;
655 
656 	io_for_each_link(req, head) {
657 		if (req->flags & REQ_F_INFLIGHT)
658 			return true;
659 	}
660 	return false;
661 }
662 
663 /* Returns true if we found and killed one or more timeouts */
664 __cold bool io_kill_timeouts(struct io_ring_ctx *ctx, struct task_struct *tsk,
665 			     bool cancel_all)
666 {
667 	struct io_timeout *timeout, *tmp;
668 	int canceled = 0;
669 
670 	/*
671 	 * completion_lock is needed for io_match_task(). Take it before
672 	 * timeout_lockfirst to keep locking ordering.
673 	 */
674 	spin_lock(&ctx->completion_lock);
675 	spin_lock_irq(&ctx->timeout_lock);
676 	list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {
677 		struct io_kiocb *req = cmd_to_io_kiocb(timeout);
678 
679 		if (io_match_task(req, tsk, cancel_all) &&
680 		    io_kill_timeout(req, -ECANCELED))
681 			canceled++;
682 	}
683 	spin_unlock_irq(&ctx->timeout_lock);
684 	spin_unlock(&ctx->completion_lock);
685 	return canceled != 0;
686 }
687