xref: /linux/io_uring/timeout.c (revision c83c846231db8b153bfcb44d552d373c34f78245)
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 		if (io_req_post_cqe(req, -ETIME, IORING_CQE_F_MORE)) {
76 			/* re-arm timer */
77 			raw_spin_lock_irq(&ctx->timeout_lock);
78 			list_add(&timeout->list, ctx->timeout_list.prev);
79 			hrtimer_start(&data->timer, timespec64_to_ktime(data->ts), data->mode);
80 			raw_spin_unlock_irq(&ctx->timeout_lock);
81 			return;
82 		}
83 	}
84 
85 	io_req_task_complete(req, ts);
86 }
87 
88 static __cold bool io_flush_killed_timeouts(struct list_head *list, int err)
89 {
90 	if (list_empty(list))
91 		return false;
92 
93 	while (!list_empty(list)) {
94 		struct io_timeout *timeout;
95 		struct io_kiocb *req;
96 
97 		timeout = list_first_entry(list, struct io_timeout, list);
98 		list_del_init(&timeout->list);
99 		req = cmd_to_io_kiocb(timeout);
100 		if (err)
101 			req_set_fail(req);
102 		io_req_queue_tw_complete(req, err);
103 	}
104 
105 	return true;
106 }
107 
108 static void io_kill_timeout(struct io_kiocb *req, struct list_head *list)
109 	__must_hold(&req->ctx->timeout_lock)
110 {
111 	struct io_timeout_data *io = req->async_data;
112 
113 	if (hrtimer_try_to_cancel(&io->timer) != -1) {
114 		struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
115 
116 		atomic_set(&req->ctx->cq_timeouts,
117 			atomic_read(&req->ctx->cq_timeouts) + 1);
118 		list_move_tail(&timeout->list, list);
119 	}
120 }
121 
122 __cold void io_flush_timeouts(struct io_ring_ctx *ctx)
123 {
124 	struct io_timeout *timeout, *tmp;
125 	LIST_HEAD(list);
126 	u32 seq;
127 
128 	raw_spin_lock_irq(&ctx->timeout_lock);
129 	seq = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
130 
131 	list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {
132 		struct io_kiocb *req = cmd_to_io_kiocb(timeout);
133 		u32 events_needed, events_got;
134 
135 		if (io_is_timeout_noseq(req))
136 			break;
137 
138 		/*
139 		 * Since seq can easily wrap around over time, subtract
140 		 * the last seq at which timeouts were flushed before comparing.
141 		 * Assuming not more than 2^31-1 events have happened since,
142 		 * these subtractions won't have wrapped, so we can check if
143 		 * target is in [last_seq, current_seq] by comparing the two.
144 		 */
145 		events_needed = timeout->target_seq - ctx->cq_last_tm_flush;
146 		events_got = seq - ctx->cq_last_tm_flush;
147 		if (events_got < events_needed)
148 			break;
149 
150 		io_kill_timeout(req, &list);
151 	}
152 	ctx->cq_last_tm_flush = seq;
153 	raw_spin_unlock_irq(&ctx->timeout_lock);
154 	io_flush_killed_timeouts(&list, 0);
155 }
156 
157 static void io_req_tw_fail_links(struct io_kiocb *link, struct io_tw_state *ts)
158 {
159 	io_tw_lock(link->ctx, ts);
160 	while (link) {
161 		struct io_kiocb *nxt = link->link;
162 		long res = -ECANCELED;
163 
164 		if (link->flags & REQ_F_FAIL)
165 			res = link->cqe.res;
166 		link->link = NULL;
167 		io_req_set_res(link, res, 0);
168 		io_req_task_complete(link, ts);
169 		link = nxt;
170 	}
171 }
172 
173 static void io_fail_links(struct io_kiocb *req)
174 	__must_hold(&req->ctx->completion_lock)
175 {
176 	struct io_kiocb *link = req->link;
177 	bool ignore_cqes = req->flags & REQ_F_SKIP_LINK_CQES;
178 
179 	if (!link)
180 		return;
181 
182 	while (link) {
183 		if (ignore_cqes)
184 			link->flags |= REQ_F_CQE_SKIP;
185 		else
186 			link->flags &= ~REQ_F_CQE_SKIP;
187 		trace_io_uring_fail_link(req, link);
188 		link = link->link;
189 	}
190 
191 	link = req->link;
192 	link->io_task_work.func = io_req_tw_fail_links;
193 	io_req_task_work_add(link);
194 	req->link = NULL;
195 }
196 
197 static inline void io_remove_next_linked(struct io_kiocb *req)
198 {
199 	struct io_kiocb *nxt = req->link;
200 
201 	req->link = nxt->link;
202 	nxt->link = NULL;
203 }
204 
205 void io_disarm_next(struct io_kiocb *req)
206 	__must_hold(&req->ctx->completion_lock)
207 {
208 	struct io_kiocb *link = NULL;
209 
210 	if (req->flags & REQ_F_ARM_LTIMEOUT) {
211 		link = req->link;
212 		req->flags &= ~REQ_F_ARM_LTIMEOUT;
213 		if (link && link->opcode == IORING_OP_LINK_TIMEOUT) {
214 			io_remove_next_linked(req);
215 			io_req_queue_tw_complete(link, -ECANCELED);
216 		}
217 	} else if (req->flags & REQ_F_LINK_TIMEOUT) {
218 		struct io_ring_ctx *ctx = req->ctx;
219 
220 		raw_spin_lock_irq(&ctx->timeout_lock);
221 		link = io_disarm_linked_timeout(req);
222 		raw_spin_unlock_irq(&ctx->timeout_lock);
223 		if (link)
224 			io_req_queue_tw_complete(link, -ECANCELED);
225 	}
226 	if (unlikely((req->flags & REQ_F_FAIL) &&
227 		     !(req->flags & REQ_F_HARDLINK)))
228 		io_fail_links(req);
229 }
230 
231 struct io_kiocb *__io_disarm_linked_timeout(struct io_kiocb *req,
232 					    struct io_kiocb *link)
233 	__must_hold(&req->ctx->completion_lock)
234 	__must_hold(&req->ctx->timeout_lock)
235 {
236 	struct io_timeout_data *io = link->async_data;
237 	struct io_timeout *timeout = io_kiocb_to_cmd(link, struct io_timeout);
238 
239 	io_remove_next_linked(req);
240 	timeout->head = NULL;
241 	if (hrtimer_try_to_cancel(&io->timer) != -1) {
242 		list_del(&timeout->list);
243 		return link;
244 	}
245 
246 	return NULL;
247 }
248 
249 static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
250 {
251 	struct io_timeout_data *data = container_of(timer,
252 						struct io_timeout_data, timer);
253 	struct io_kiocb *req = data->req;
254 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
255 	struct io_ring_ctx *ctx = req->ctx;
256 	unsigned long flags;
257 
258 	raw_spin_lock_irqsave(&ctx->timeout_lock, flags);
259 	list_del_init(&timeout->list);
260 	atomic_set(&req->ctx->cq_timeouts,
261 		atomic_read(&req->ctx->cq_timeouts) + 1);
262 	raw_spin_unlock_irqrestore(&ctx->timeout_lock, flags);
263 
264 	if (!(data->flags & IORING_TIMEOUT_ETIME_SUCCESS))
265 		req_set_fail(req);
266 
267 	io_req_set_res(req, -ETIME, 0);
268 	req->io_task_work.func = io_timeout_complete;
269 	io_req_task_work_add(req);
270 	return HRTIMER_NORESTART;
271 }
272 
273 static struct io_kiocb *io_timeout_extract(struct io_ring_ctx *ctx,
274 					   struct io_cancel_data *cd)
275 	__must_hold(&ctx->timeout_lock)
276 {
277 	struct io_timeout *timeout;
278 	struct io_timeout_data *io;
279 	struct io_kiocb *req = NULL;
280 
281 	list_for_each_entry(timeout, &ctx->timeout_list, list) {
282 		struct io_kiocb *tmp = cmd_to_io_kiocb(timeout);
283 
284 		if (io_cancel_req_match(tmp, cd)) {
285 			req = tmp;
286 			break;
287 		}
288 	}
289 	if (!req)
290 		return ERR_PTR(-ENOENT);
291 
292 	io = req->async_data;
293 	if (hrtimer_try_to_cancel(&io->timer) == -1)
294 		return ERR_PTR(-EALREADY);
295 	timeout = io_kiocb_to_cmd(req, struct io_timeout);
296 	list_del_init(&timeout->list);
297 	return req;
298 }
299 
300 int io_timeout_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
301 	__must_hold(&ctx->completion_lock)
302 {
303 	struct io_kiocb *req;
304 
305 	raw_spin_lock_irq(&ctx->timeout_lock);
306 	req = io_timeout_extract(ctx, cd);
307 	raw_spin_unlock_irq(&ctx->timeout_lock);
308 
309 	if (IS_ERR(req))
310 		return PTR_ERR(req);
311 	io_req_task_queue_fail(req, -ECANCELED);
312 	return 0;
313 }
314 
315 static void io_req_task_link_timeout(struct io_kiocb *req, struct io_tw_state *ts)
316 {
317 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
318 	struct io_kiocb *prev = timeout->prev;
319 	int ret;
320 
321 	if (prev) {
322 		if (!io_should_terminate_tw()) {
323 			struct io_cancel_data cd = {
324 				.ctx		= req->ctx,
325 				.data		= prev->cqe.user_data,
326 			};
327 
328 			ret = io_try_cancel(req->tctx, &cd, 0);
329 		} else {
330 			ret = -ECANCELED;
331 		}
332 		io_req_set_res(req, ret ?: -ETIME, 0);
333 		io_req_task_complete(req, ts);
334 		io_put_req(prev);
335 	} else {
336 		io_req_set_res(req, -ETIME, 0);
337 		io_req_task_complete(req, ts);
338 	}
339 }
340 
341 static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
342 {
343 	struct io_timeout_data *data = container_of(timer,
344 						struct io_timeout_data, timer);
345 	struct io_kiocb *prev, *req = data->req;
346 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
347 	struct io_ring_ctx *ctx = req->ctx;
348 	unsigned long flags;
349 
350 	raw_spin_lock_irqsave(&ctx->timeout_lock, flags);
351 	prev = timeout->head;
352 	timeout->head = NULL;
353 
354 	/*
355 	 * We don't expect the list to be empty, that will only happen if we
356 	 * race with the completion of the linked work.
357 	 */
358 	if (prev) {
359 		io_remove_next_linked(prev);
360 		if (!req_ref_inc_not_zero(prev))
361 			prev = NULL;
362 	}
363 	list_del(&timeout->list);
364 	timeout->prev = prev;
365 	raw_spin_unlock_irqrestore(&ctx->timeout_lock, flags);
366 
367 	req->io_task_work.func = io_req_task_link_timeout;
368 	io_req_task_work_add(req);
369 	return HRTIMER_NORESTART;
370 }
371 
372 static clockid_t io_timeout_get_clock(struct io_timeout_data *data)
373 {
374 	switch (data->flags & IORING_TIMEOUT_CLOCK_MASK) {
375 	case IORING_TIMEOUT_BOOTTIME:
376 		return CLOCK_BOOTTIME;
377 	case IORING_TIMEOUT_REALTIME:
378 		return CLOCK_REALTIME;
379 	default:
380 		/* can't happen, vetted at prep time */
381 		WARN_ON_ONCE(1);
382 		fallthrough;
383 	case 0:
384 		return CLOCK_MONOTONIC;
385 	}
386 }
387 
388 static int io_linked_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
389 				    struct timespec64 *ts, enum hrtimer_mode mode)
390 	__must_hold(&ctx->timeout_lock)
391 {
392 	struct io_timeout_data *io;
393 	struct io_timeout *timeout;
394 	struct io_kiocb *req = NULL;
395 
396 	list_for_each_entry(timeout, &ctx->ltimeout_list, list) {
397 		struct io_kiocb *tmp = cmd_to_io_kiocb(timeout);
398 
399 		if (user_data == tmp->cqe.user_data) {
400 			req = tmp;
401 			break;
402 		}
403 	}
404 	if (!req)
405 		return -ENOENT;
406 
407 	io = req->async_data;
408 	if (hrtimer_try_to_cancel(&io->timer) == -1)
409 		return -EALREADY;
410 	hrtimer_init(&io->timer, io_timeout_get_clock(io), mode);
411 	io->timer.function = io_link_timeout_fn;
412 	hrtimer_start(&io->timer, timespec64_to_ktime(*ts), mode);
413 	return 0;
414 }
415 
416 static int io_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
417 			     struct timespec64 *ts, enum hrtimer_mode mode)
418 	__must_hold(&ctx->timeout_lock)
419 {
420 	struct io_cancel_data cd = { .ctx = ctx, .data = user_data, };
421 	struct io_kiocb *req = io_timeout_extract(ctx, &cd);
422 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
423 	struct io_timeout_data *data;
424 
425 	if (IS_ERR(req))
426 		return PTR_ERR(req);
427 
428 	timeout->off = 0; /* noseq */
429 	data = req->async_data;
430 	data->ts = *ts;
431 
432 	list_add_tail(&timeout->list, &ctx->timeout_list);
433 	hrtimer_init(&data->timer, io_timeout_get_clock(data), mode);
434 	data->timer.function = io_timeout_fn;
435 	hrtimer_start(&data->timer, timespec64_to_ktime(data->ts), mode);
436 	return 0;
437 }
438 
439 int io_timeout_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
440 {
441 	struct io_timeout_rem *tr = io_kiocb_to_cmd(req, struct io_timeout_rem);
442 
443 	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
444 		return -EINVAL;
445 	if (sqe->buf_index || sqe->len || sqe->splice_fd_in)
446 		return -EINVAL;
447 
448 	tr->ltimeout = false;
449 	tr->addr = READ_ONCE(sqe->addr);
450 	tr->flags = READ_ONCE(sqe->timeout_flags);
451 	if (tr->flags & IORING_TIMEOUT_UPDATE_MASK) {
452 		if (hweight32(tr->flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
453 			return -EINVAL;
454 		if (tr->flags & IORING_LINK_TIMEOUT_UPDATE)
455 			tr->ltimeout = true;
456 		if (tr->flags & ~(IORING_TIMEOUT_UPDATE_MASK|IORING_TIMEOUT_ABS))
457 			return -EINVAL;
458 		if (get_timespec64(&tr->ts, u64_to_user_ptr(sqe->addr2)))
459 			return -EFAULT;
460 		if (tr->ts.tv_sec < 0 || tr->ts.tv_nsec < 0)
461 			return -EINVAL;
462 	} else if (tr->flags) {
463 		/* timeout removal doesn't support flags */
464 		return -EINVAL;
465 	}
466 
467 	return 0;
468 }
469 
470 static inline enum hrtimer_mode io_translate_timeout_mode(unsigned int flags)
471 {
472 	return (flags & IORING_TIMEOUT_ABS) ? HRTIMER_MODE_ABS
473 					    : HRTIMER_MODE_REL;
474 }
475 
476 /*
477  * Remove or update an existing timeout command
478  */
479 int io_timeout_remove(struct io_kiocb *req, unsigned int issue_flags)
480 {
481 	struct io_timeout_rem *tr = io_kiocb_to_cmd(req, struct io_timeout_rem);
482 	struct io_ring_ctx *ctx = req->ctx;
483 	int ret;
484 
485 	if (!(tr->flags & IORING_TIMEOUT_UPDATE)) {
486 		struct io_cancel_data cd = { .ctx = ctx, .data = tr->addr, };
487 
488 		spin_lock(&ctx->completion_lock);
489 		ret = io_timeout_cancel(ctx, &cd);
490 		spin_unlock(&ctx->completion_lock);
491 	} else {
492 		enum hrtimer_mode mode = io_translate_timeout_mode(tr->flags);
493 
494 		raw_spin_lock_irq(&ctx->timeout_lock);
495 		if (tr->ltimeout)
496 			ret = io_linked_timeout_update(ctx, tr->addr, &tr->ts, mode);
497 		else
498 			ret = io_timeout_update(ctx, tr->addr, &tr->ts, mode);
499 		raw_spin_unlock_irq(&ctx->timeout_lock);
500 	}
501 
502 	if (ret < 0)
503 		req_set_fail(req);
504 	io_req_set_res(req, ret, 0);
505 	return IOU_OK;
506 }
507 
508 static int __io_timeout_prep(struct io_kiocb *req,
509 			     const struct io_uring_sqe *sqe,
510 			     bool is_timeout_link)
511 {
512 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
513 	struct io_timeout_data *data;
514 	unsigned flags;
515 	u32 off = READ_ONCE(sqe->off);
516 
517 	if (sqe->buf_index || sqe->len != 1 || sqe->splice_fd_in)
518 		return -EINVAL;
519 	if (off && is_timeout_link)
520 		return -EINVAL;
521 	flags = READ_ONCE(sqe->timeout_flags);
522 	if (flags & ~(IORING_TIMEOUT_ABS | IORING_TIMEOUT_CLOCK_MASK |
523 		      IORING_TIMEOUT_ETIME_SUCCESS |
524 		      IORING_TIMEOUT_MULTISHOT))
525 		return -EINVAL;
526 	/* more than one clock specified is invalid, obviously */
527 	if (hweight32(flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
528 		return -EINVAL;
529 	/* multishot requests only make sense with rel values */
530 	if (!(~flags & (IORING_TIMEOUT_MULTISHOT | IORING_TIMEOUT_ABS)))
531 		return -EINVAL;
532 
533 	INIT_LIST_HEAD(&timeout->list);
534 	timeout->off = off;
535 	if (unlikely(off && !req->ctx->off_timeout_used))
536 		req->ctx->off_timeout_used = true;
537 	/*
538 	 * for multishot reqs w/ fixed nr of repeats, repeats tracks the
539 	 * remaining nr
540 	 */
541 	timeout->repeats = 0;
542 	if ((flags & IORING_TIMEOUT_MULTISHOT) && off > 0)
543 		timeout->repeats = off;
544 
545 	if (WARN_ON_ONCE(req_has_async_data(req)))
546 		return -EFAULT;
547 	if (io_alloc_async_data(req))
548 		return -ENOMEM;
549 
550 	data = req->async_data;
551 	data->req = req;
552 	data->flags = flags;
553 
554 	if (get_timespec64(&data->ts, u64_to_user_ptr(sqe->addr)))
555 		return -EFAULT;
556 
557 	if (data->ts.tv_sec < 0 || data->ts.tv_nsec < 0)
558 		return -EINVAL;
559 
560 	data->mode = io_translate_timeout_mode(flags);
561 	hrtimer_init(&data->timer, io_timeout_get_clock(data), data->mode);
562 
563 	if (is_timeout_link) {
564 		struct io_submit_link *link = &req->ctx->submit_state.link;
565 
566 		if (!link->head)
567 			return -EINVAL;
568 		if (link->last->opcode == IORING_OP_LINK_TIMEOUT)
569 			return -EINVAL;
570 		timeout->head = link->last;
571 		link->last->flags |= REQ_F_ARM_LTIMEOUT;
572 	}
573 	return 0;
574 }
575 
576 int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
577 {
578 	return __io_timeout_prep(req, sqe, false);
579 }
580 
581 int io_link_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
582 {
583 	return __io_timeout_prep(req, sqe, true);
584 }
585 
586 int io_timeout(struct io_kiocb *req, unsigned int issue_flags)
587 {
588 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
589 	struct io_ring_ctx *ctx = req->ctx;
590 	struct io_timeout_data *data = req->async_data;
591 	struct list_head *entry;
592 	u32 tail, off = timeout->off;
593 
594 	raw_spin_lock_irq(&ctx->timeout_lock);
595 
596 	/*
597 	 * sqe->off holds how many events that need to occur for this
598 	 * timeout event to be satisfied. If it isn't set, then this is
599 	 * a pure timeout request, sequence isn't used.
600 	 */
601 	if (io_is_timeout_noseq(req)) {
602 		entry = ctx->timeout_list.prev;
603 		goto add;
604 	}
605 
606 	tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts);
607 	timeout->target_seq = tail + off;
608 
609 	/* Update the last seq here in case io_flush_timeouts() hasn't.
610 	 * This is safe because ->completion_lock is held, and submissions
611 	 * and completions are never mixed in the same ->completion_lock section.
612 	 */
613 	ctx->cq_last_tm_flush = tail;
614 
615 	/*
616 	 * Insertion sort, ensuring the first entry in the list is always
617 	 * the one we need first.
618 	 */
619 	list_for_each_prev(entry, &ctx->timeout_list) {
620 		struct io_timeout *nextt = list_entry(entry, struct io_timeout, list);
621 		struct io_kiocb *nxt = cmd_to_io_kiocb(nextt);
622 
623 		if (io_is_timeout_noseq(nxt))
624 			continue;
625 		/* nxt.seq is behind @tail, otherwise would've been completed */
626 		if (off >= nextt->target_seq - tail)
627 			break;
628 	}
629 add:
630 	list_add(&timeout->list, entry);
631 	data->timer.function = io_timeout_fn;
632 	hrtimer_start(&data->timer, timespec64_to_ktime(data->ts), data->mode);
633 	raw_spin_unlock_irq(&ctx->timeout_lock);
634 	return IOU_ISSUE_SKIP_COMPLETE;
635 }
636 
637 void io_queue_linked_timeout(struct io_kiocb *req)
638 {
639 	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
640 	struct io_ring_ctx *ctx = req->ctx;
641 
642 	raw_spin_lock_irq(&ctx->timeout_lock);
643 	/*
644 	 * If the back reference is NULL, then our linked request finished
645 	 * before we got a chance to setup the timer
646 	 */
647 	if (timeout->head) {
648 		struct io_timeout_data *data = req->async_data;
649 
650 		data->timer.function = io_link_timeout_fn;
651 		hrtimer_start(&data->timer, timespec64_to_ktime(data->ts),
652 				data->mode);
653 		list_add_tail(&timeout->list, &ctx->ltimeout_list);
654 	}
655 	raw_spin_unlock_irq(&ctx->timeout_lock);
656 	/* drop submission reference */
657 	io_put_req(req);
658 }
659 
660 static bool io_match_task(struct io_kiocb *head, struct io_uring_task *tctx,
661 			  bool cancel_all)
662 	__must_hold(&head->ctx->timeout_lock)
663 {
664 	struct io_kiocb *req;
665 
666 	if (tctx && head->tctx != tctx)
667 		return false;
668 	if (cancel_all)
669 		return true;
670 
671 	io_for_each_link(req, head) {
672 		if (req->flags & REQ_F_INFLIGHT)
673 			return true;
674 	}
675 	return false;
676 }
677 
678 /* Returns true if we found and killed one or more timeouts */
679 __cold bool io_kill_timeouts(struct io_ring_ctx *ctx, struct io_uring_task *tctx,
680 			     bool cancel_all)
681 {
682 	struct io_timeout *timeout, *tmp;
683 	LIST_HEAD(list);
684 
685 	/*
686 	 * completion_lock is needed for io_match_task(). Take it before
687 	 * timeout_lockfirst to keep locking ordering.
688 	 */
689 	spin_lock(&ctx->completion_lock);
690 	raw_spin_lock_irq(&ctx->timeout_lock);
691 	list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {
692 		struct io_kiocb *req = cmd_to_io_kiocb(timeout);
693 
694 		if (io_match_task(req, tctx, cancel_all))
695 			io_kill_timeout(req, &list);
696 	}
697 	raw_spin_unlock_irq(&ctx->timeout_lock);
698 	spin_unlock(&ctx->completion_lock);
699 
700 	return io_flush_killed_timeouts(&list, -ECANCELED);
701 }
702