1 // SPDX-License-Identifier: GPL-2.0
3 * Shared application/kernel submission and completion ring pairs, for
4 * supporting fast/efficient IO.
6 * A note on the read/write ordering memory barriers that are matched between
7 * the application and kernel side.
9 * After the application reads the CQ ring tail, it must use an
10 * appropriate smp_rmb() to pair with the smp_wmb() the kernel uses
11 * before writing the tail (using smp_load_acquire to read the tail will
12 * do). It also needs a smp_mb() before updating CQ head (ordering the
13 * entry load(s) with the head store), pairing with an implicit barrier
14 * through a control-dependency in io_get_cqring (smp_store_release to
15 * store head will do). Failure to do so could lead to reading invalid
18 * Likewise, the application must use an appropriate smp_wmb() before
19 * writing the SQ tail (ordering SQ entry stores with the tail store),
20 * which pairs with smp_load_acquire in io_get_sqring (smp_store_release
21 * to store the tail will do). And it needs a barrier ordering the SQ
22 * head load before writing new SQ entries (smp_load_acquire to read
25 * When using the SQ poll thread (IORING_SETUP_SQPOLL), the application
26 * needs to check the SQ flags for IORING_SQ_NEED_WAKEUP *after*
27 * updating the SQ tail; a full memory barrier smp_mb() is needed
30 * Also see the examples in the liburing library:
32 * git://git.kernel.dk/liburing
34 * io_uring also uses READ/WRITE_ONCE() for _any_ store or load that happens
35 * from data shared between the kernel and application. This is done both
36 * for ordering purposes, but also to ensure that once a value is loaded from
37 * data that the application could potentially modify, it remains stable.
39 * Copyright (C) 2018-2019 Jens Axboe
40 * Copyright (c) 2018-2019 Christoph Hellwig
42 #include <linux/kernel.h>
43 #include <linux/init.h>
44 #include <linux/errno.h>
45 #include <linux/syscalls.h>
46 #include <linux/compat.h>
47 #include <linux/refcount.h>
48 #include <linux/uio.h>
50 #include <linux/sched/signal.h>
52 #include <linux/file.h>
53 #include <linux/fdtable.h>
55 #include <linux/mman.h>
56 #include <linux/mmu_context.h>
57 #include <linux/percpu.h>
58 #include <linux/slab.h>
59 #include <linux/workqueue.h>
60 #include <linux/kthread.h>
61 #include <linux/blkdev.h>
62 #include <linux/bvec.h>
63 #include <linux/net.h>
65 #include <net/af_unix.h>
67 #include <linux/anon_inodes.h>
68 #include <linux/sched/mm.h>
69 #include <linux/uaccess.h>
70 #include <linux/nospec.h>
71 #include <linux/sizes.h>
72 #include <linux/hugetlb.h>
74 #include <uapi/linux/io_uring.h>
78 #define IORING_MAX_ENTRIES 32768
79 #define IORING_MAX_FIXED_FILES 1024
82 u32 head ____cacheline_aligned_in_smp;
83 u32 tail ____cacheline_aligned_in_smp;
87 * This data is shared with the application through the mmap at offsets
88 * IORING_OFF_SQ_RING and IORING_OFF_CQ_RING.
90 * The offsets to the member fields are published through struct
91 * io_sqring_offsets when calling io_uring_setup.
95 * Head and tail offsets into the ring; the offsets need to be
96 * masked to get valid indices.
98 * The kernel controls head of the sq ring and the tail of the cq ring,
99 * and the application controls tail of the sq ring and the head of the
102 struct io_uring sq, cq;
104 * Bitmasks to apply to head and tail offsets (constant, equals
107 u32 sq_ring_mask, cq_ring_mask;
108 /* Ring sizes (constant, power of 2) */
109 u32 sq_ring_entries, cq_ring_entries;
111 * Number of invalid entries dropped by the kernel due to
112 * invalid index stored in array
114 * Written by the kernel, shouldn't be modified by the
115 * application (i.e. get number of "new events" by comparing to
118 * After a new SQ head value was read by the application this
119 * counter includes all submissions that were dropped reaching
120 * the new SQ head (and possibly more).
126 * Written by the kernel, shouldn't be modified by the
129 * The application needs a full memory barrier before checking
130 * for IORING_SQ_NEED_WAKEUP after updating the sq tail.
134 * Number of completion events lost because the queue was full;
135 * this should be avoided by the application by making sure
136 * there are not more requests pending thatn there is space in
137 * the completion queue.
139 * Written by the kernel, shouldn't be modified by the
140 * application (i.e. get number of "new events" by comparing to
143 * As completion events come in out of order this counter is not
144 * ordered with any other data.
148 * Ring buffer of completion events.
150 * The kernel writes completion events fresh every time they are
151 * produced, so the application is allowed to modify pending
154 struct io_uring_cqe cqes[] ____cacheline_aligned_in_smp;
157 struct io_mapped_ubuf {
160 struct bio_vec *bvec;
161 unsigned int nr_bvecs;
167 struct list_head list;
176 struct percpu_ref refs;
177 } ____cacheline_aligned_in_smp;
185 * Ring buffer of indices into array of io_uring_sqe, which is
186 * mmapped by the application using the IORING_OFF_SQES offset.
188 * This indirection could e.g. be used to assign fixed
189 * io_uring_sqe entries to operations and only submit them to
190 * the queue when needed.
192 * The kernel modifies neither the indices array nor the entries
196 unsigned cached_sq_head;
199 unsigned sq_thread_idle;
200 struct io_uring_sqe *sq_sqes;
202 struct list_head defer_list;
203 struct list_head timeout_list;
204 } ____cacheline_aligned_in_smp;
207 struct workqueue_struct *sqo_wq[2];
208 struct task_struct *sqo_thread; /* if using sq thread polling */
209 struct mm_struct *sqo_mm;
210 wait_queue_head_t sqo_wait;
211 struct completion sqo_thread_started;
214 unsigned cached_cq_tail;
217 struct wait_queue_head cq_wait;
218 struct fasync_struct *cq_fasync;
219 struct eventfd_ctx *cq_ev_fd;
220 atomic_t cq_timeouts;
221 } ____cacheline_aligned_in_smp;
223 struct io_rings *rings;
226 * If used, fixed file set. Writers must ensure that ->refs is dead,
227 * readers must ensure that ->refs is alive as long as the file* is
228 * used. Only updated through io_uring_register(2).
230 struct file **user_files;
231 unsigned nr_user_files;
233 /* if used, fixed mapped user buffers */
234 unsigned nr_user_bufs;
235 struct io_mapped_ubuf *user_bufs;
237 struct user_struct *user;
239 struct completion ctx_done;
242 struct mutex uring_lock;
243 wait_queue_head_t wait;
244 } ____cacheline_aligned_in_smp;
247 spinlock_t completion_lock;
248 bool poll_multi_file;
250 * ->poll_list is protected by the ctx->uring_lock for
251 * io_uring instances that don't use IORING_SETUP_SQPOLL.
252 * For SQPOLL, only the single threaded io_sq_thread() will
253 * manipulate the list, hence no extra locking is needed there.
255 struct list_head poll_list;
256 struct list_head cancel_list;
257 } ____cacheline_aligned_in_smp;
259 struct async_list pending_async[2];
261 #if defined(CONFIG_UNIX)
262 struct socket *ring_sock;
267 const struct io_uring_sqe *sqe;
268 unsigned short index;
272 bool needs_fixed_file;
276 * First field must be the file pointer in all the
277 * iocb unions! See also 'struct kiocb' in <linux/fs.h>
279 struct io_poll_iocb {
281 struct wait_queue_head *head;
285 struct wait_queue_entry wait;
290 struct hrtimer timer;
294 * NOTE! Each of the iocb union members has the file pointer
295 * as the first entry in their struct definition. So you can
296 * access the file pointer through any of the sub-structs,
297 * or directly as just 'ki_filp' in this struct.
303 struct io_poll_iocb poll;
304 struct io_timeout timeout;
307 struct sqe_submit submit;
309 struct io_ring_ctx *ctx;
310 struct list_head list;
311 struct list_head link_list;
314 #define REQ_F_NOWAIT 1 /* must not punt to workers */
315 #define REQ_F_IOPOLL_COMPLETED 2 /* polled IO has completed */
316 #define REQ_F_FIXED_FILE 4 /* ctx owns file */
317 #define REQ_F_SEQ_PREV 8 /* sequential with previous */
318 #define REQ_F_IO_DRAIN 16 /* drain existing IO first */
319 #define REQ_F_IO_DRAINED 32 /* drain done */
320 #define REQ_F_LINK 64 /* linked sqes */
321 #define REQ_F_LINK_DONE 128 /* linked sqes done */
322 #define REQ_F_FAIL_LINK 256 /* fail rest of links */
323 #define REQ_F_SHADOW_DRAIN 512 /* link-drain shadow req */
324 #define REQ_F_TIMEOUT 1024 /* timeout request */
329 struct work_struct work;
332 #define IO_PLUG_THRESHOLD 2
333 #define IO_IOPOLL_BATCH 8
335 struct io_submit_state {
336 struct blk_plug plug;
339 * io_kiocb alloc cache
341 void *reqs[IO_IOPOLL_BATCH];
342 unsigned int free_reqs;
343 unsigned int cur_req;
346 * File reference cache
350 unsigned int has_refs;
351 unsigned int used_refs;
352 unsigned int ios_left;
355 static void io_sq_wq_submit_work(struct work_struct *work);
356 static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
358 static void __io_free_req(struct io_kiocb *req);
360 static struct kmem_cache *req_cachep;
362 static const struct file_operations io_uring_fops;
364 struct sock *io_uring_get_socket(struct file *file)
366 #if defined(CONFIG_UNIX)
367 if (file->f_op == &io_uring_fops) {
368 struct io_ring_ctx *ctx = file->private_data;
370 return ctx->ring_sock->sk;
375 EXPORT_SYMBOL(io_uring_get_socket);
377 static void io_ring_ctx_ref_free(struct percpu_ref *ref)
379 struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
381 complete(&ctx->ctx_done);
384 static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
386 struct io_ring_ctx *ctx;
389 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
393 if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
394 PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
399 ctx->flags = p->flags;
400 init_waitqueue_head(&ctx->cq_wait);
401 init_completion(&ctx->ctx_done);
402 init_completion(&ctx->sqo_thread_started);
403 mutex_init(&ctx->uring_lock);
404 init_waitqueue_head(&ctx->wait);
405 for (i = 0; i < ARRAY_SIZE(ctx->pending_async); i++) {
406 spin_lock_init(&ctx->pending_async[i].lock);
407 INIT_LIST_HEAD(&ctx->pending_async[i].list);
408 atomic_set(&ctx->pending_async[i].cnt, 0);
410 spin_lock_init(&ctx->completion_lock);
411 INIT_LIST_HEAD(&ctx->poll_list);
412 INIT_LIST_HEAD(&ctx->cancel_list);
413 INIT_LIST_HEAD(&ctx->defer_list);
414 INIT_LIST_HEAD(&ctx->timeout_list);
418 static inline bool io_sequence_defer(struct io_ring_ctx *ctx,
419 struct io_kiocb *req)
421 /* timeout requests always honor sequence */
422 if (!(req->flags & REQ_F_TIMEOUT) &&
423 (req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
426 return req->sequence != ctx->cached_cq_tail + ctx->rings->sq_dropped;
429 static struct io_kiocb *__io_get_deferred_req(struct io_ring_ctx *ctx,
430 struct list_head *list)
432 struct io_kiocb *req;
434 if (list_empty(list))
437 req = list_first_entry(list, struct io_kiocb, list);
438 if (!io_sequence_defer(ctx, req)) {
439 list_del_init(&req->list);
446 static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)
448 return __io_get_deferred_req(ctx, &ctx->defer_list);
451 static struct io_kiocb *io_get_timeout_req(struct io_ring_ctx *ctx)
453 return __io_get_deferred_req(ctx, &ctx->timeout_list);
456 static void __io_commit_cqring(struct io_ring_ctx *ctx)
458 struct io_rings *rings = ctx->rings;
460 if (ctx->cached_cq_tail != READ_ONCE(rings->cq.tail)) {
461 /* order cqe stores with ring update */
462 smp_store_release(&rings->cq.tail, ctx->cached_cq_tail);
464 if (wq_has_sleeper(&ctx->cq_wait)) {
465 wake_up_interruptible(&ctx->cq_wait);
466 kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
471 static inline void io_queue_async_work(struct io_ring_ctx *ctx,
472 struct io_kiocb *req)
476 if (req->submit.sqe) {
477 switch (req->submit.sqe->opcode) {
478 case IORING_OP_WRITEV:
479 case IORING_OP_WRITE_FIXED:
480 rw = !(req->rw.ki_flags & IOCB_DIRECT);
485 queue_work(ctx->sqo_wq[rw], &req->work);
488 static void io_kill_timeout(struct io_kiocb *req)
492 ret = hrtimer_try_to_cancel(&req->timeout.timer);
494 atomic_inc(&req->ctx->cq_timeouts);
495 list_del(&req->list);
496 io_cqring_fill_event(req->ctx, req->user_data, 0);
501 static void io_kill_timeouts(struct io_ring_ctx *ctx)
503 struct io_kiocb *req, *tmp;
505 spin_lock_irq(&ctx->completion_lock);
506 list_for_each_entry_safe(req, tmp, &ctx->timeout_list, list)
507 io_kill_timeout(req);
508 spin_unlock_irq(&ctx->completion_lock);
511 static void io_commit_cqring(struct io_ring_ctx *ctx)
513 struct io_kiocb *req;
515 while ((req = io_get_timeout_req(ctx)) != NULL)
516 io_kill_timeout(req);
518 __io_commit_cqring(ctx);
520 while ((req = io_get_deferred_req(ctx)) != NULL) {
521 if (req->flags & REQ_F_SHADOW_DRAIN) {
522 /* Just for drain, free it. */
526 req->flags |= REQ_F_IO_DRAINED;
527 io_queue_async_work(ctx, req);
531 static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
533 struct io_rings *rings = ctx->rings;
536 tail = ctx->cached_cq_tail;
538 * writes to the cq entry need to come after reading head; the
539 * control dependency is enough as we're using WRITE_ONCE to
542 if (tail - READ_ONCE(rings->cq.head) == rings->cq_ring_entries)
545 ctx->cached_cq_tail++;
546 return &rings->cqes[tail & ctx->cq_mask];
549 static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
552 struct io_uring_cqe *cqe;
555 * If we can't get a cq entry, userspace overflowed the
556 * submission (by quite a lot). Increment the overflow count in
559 cqe = io_get_cqring(ctx);
561 WRITE_ONCE(cqe->user_data, ki_user_data);
562 WRITE_ONCE(cqe->res, res);
563 WRITE_ONCE(cqe->flags, 0);
565 unsigned overflow = READ_ONCE(ctx->rings->cq_overflow);
567 WRITE_ONCE(ctx->rings->cq_overflow, overflow + 1);
571 static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
573 if (waitqueue_active(&ctx->wait))
575 if (waitqueue_active(&ctx->sqo_wait))
576 wake_up(&ctx->sqo_wait);
578 eventfd_signal(ctx->cq_ev_fd, 1);
581 static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 user_data,
586 spin_lock_irqsave(&ctx->completion_lock, flags);
587 io_cqring_fill_event(ctx, user_data, res);
588 io_commit_cqring(ctx);
589 spin_unlock_irqrestore(&ctx->completion_lock, flags);
591 io_cqring_ev_posted(ctx);
594 static void io_ring_drop_ctx_refs(struct io_ring_ctx *ctx, unsigned refs)
596 percpu_ref_put_many(&ctx->refs, refs);
598 if (waitqueue_active(&ctx->wait))
602 static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
603 struct io_submit_state *state)
605 gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
606 struct io_kiocb *req;
608 if (!percpu_ref_tryget(&ctx->refs))
612 req = kmem_cache_alloc(req_cachep, gfp);
615 } else if (!state->free_reqs) {
619 sz = min_t(size_t, state->ios_left, ARRAY_SIZE(state->reqs));
620 ret = kmem_cache_alloc_bulk(req_cachep, gfp, sz, state->reqs);
623 * Bulk alloc is all-or-nothing. If we fail to get a batch,
624 * retry single alloc to be on the safe side.
626 if (unlikely(ret <= 0)) {
627 state->reqs[0] = kmem_cache_alloc(req_cachep, gfp);
632 state->free_reqs = ret - 1;
634 req = state->reqs[0];
636 req = state->reqs[state->cur_req];
644 /* one is dropped after submission, the other at completion */
645 refcount_set(&req->refs, 2);
649 io_ring_drop_ctx_refs(ctx, 1);
653 static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
656 kmem_cache_free_bulk(req_cachep, *nr, reqs);
657 io_ring_drop_ctx_refs(ctx, *nr);
662 static void __io_free_req(struct io_kiocb *req)
664 if (req->file && !(req->flags & REQ_F_FIXED_FILE))
666 io_ring_drop_ctx_refs(req->ctx, 1);
667 kmem_cache_free(req_cachep, req);
670 static void io_req_link_next(struct io_kiocb *req)
672 struct io_kiocb *nxt;
675 * The list should never be empty when we are called here. But could
676 * potentially happen if the chain is messed up, check to be on the
679 nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb, list);
681 list_del(&nxt->list);
682 if (!list_empty(&req->link_list)) {
683 INIT_LIST_HEAD(&nxt->link_list);
684 list_splice(&req->link_list, &nxt->link_list);
685 nxt->flags |= REQ_F_LINK;
688 nxt->flags |= REQ_F_LINK_DONE;
689 INIT_WORK(&nxt->work, io_sq_wq_submit_work);
690 io_queue_async_work(req->ctx, nxt);
695 * Called if REQ_F_LINK is set, and we fail the head request
697 static void io_fail_links(struct io_kiocb *req)
699 struct io_kiocb *link;
701 while (!list_empty(&req->link_list)) {
702 link = list_first_entry(&req->link_list, struct io_kiocb, list);
703 list_del(&link->list);
705 io_cqring_add_event(req->ctx, link->user_data, -ECANCELED);
710 static void io_free_req(struct io_kiocb *req)
713 * If LINK is set, we have dependent requests in this chain. If we
714 * didn't fail this request, queue the first one up, moving any other
715 * dependencies to the next request. In case of failure, fail the rest
718 if (req->flags & REQ_F_LINK) {
719 if (req->flags & REQ_F_FAIL_LINK)
722 io_req_link_next(req);
728 static void io_put_req(struct io_kiocb *req)
730 if (refcount_dec_and_test(&req->refs))
734 static unsigned io_cqring_events(struct io_rings *rings)
736 /* See comment at the top of this file */
738 return READ_ONCE(rings->cq.tail) - READ_ONCE(rings->cq.head);
742 * Find and free completed poll iocbs
744 static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
745 struct list_head *done)
747 void *reqs[IO_IOPOLL_BATCH];
748 struct io_kiocb *req;
752 while (!list_empty(done)) {
753 req = list_first_entry(done, struct io_kiocb, list);
754 list_del(&req->list);
756 io_cqring_fill_event(ctx, req->user_data, req->result);
759 if (refcount_dec_and_test(&req->refs)) {
760 /* If we're not using fixed files, we have to pair the
761 * completion part with the file put. Use regular
762 * completions for those, only batch free for fixed
763 * file and non-linked commands.
765 if ((req->flags & (REQ_F_FIXED_FILE|REQ_F_LINK)) ==
767 reqs[to_free++] = req;
768 if (to_free == ARRAY_SIZE(reqs))
769 io_free_req_many(ctx, reqs, &to_free);
776 io_commit_cqring(ctx);
777 io_free_req_many(ctx, reqs, &to_free);
780 static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
783 struct io_kiocb *req, *tmp;
789 * Only spin for completions if we don't have multiple devices hanging
790 * off our complete list, and we're under the requested amount.
792 spin = !ctx->poll_multi_file && *nr_events < min;
795 list_for_each_entry_safe(req, tmp, &ctx->poll_list, list) {
796 struct kiocb *kiocb = &req->rw;
799 * Move completed entries to our local list. If we find a
800 * request that requires polling, break out and complete
801 * the done list first, if we have entries there.
803 if (req->flags & REQ_F_IOPOLL_COMPLETED) {
804 list_move_tail(&req->list, &done);
807 if (!list_empty(&done))
810 ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
819 if (!list_empty(&done))
820 io_iopoll_complete(ctx, nr_events, &done);
826 * Poll for a mininum of 'min' events. Note that if min == 0 we consider that a
827 * non-spinning poll check - we'll still enter the driver poll loop, but only
828 * as a non-spinning completion check.
830 static int io_iopoll_getevents(struct io_ring_ctx *ctx, unsigned int *nr_events,
833 while (!list_empty(&ctx->poll_list) && !need_resched()) {
836 ret = io_do_iopoll(ctx, nr_events, min);
839 if (!min || *nr_events >= min)
847 * We can't just wait for polled events to come to us, we have to actively
848 * find and complete them.
850 static void io_iopoll_reap_events(struct io_ring_ctx *ctx)
852 if (!(ctx->flags & IORING_SETUP_IOPOLL))
855 mutex_lock(&ctx->uring_lock);
856 while (!list_empty(&ctx->poll_list)) {
857 unsigned int nr_events = 0;
859 io_iopoll_getevents(ctx, &nr_events, 1);
862 * Ensure we allow local-to-the-cpu processing to take place,
863 * in this case we need to ensure that we reap all events.
867 mutex_unlock(&ctx->uring_lock);
870 static int io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events,
876 * We disallow the app entering submit/complete with polling, but we
877 * still need to lock the ring to prevent racing with polled issue
878 * that got punted to a workqueue.
880 mutex_lock(&ctx->uring_lock);
887 * Don't enter poll loop if we already have events pending.
888 * If we do, we can potentially be spinning for commands that
889 * already triggered a CQE (eg in error).
891 if (io_cqring_events(ctx->rings))
895 * If a submit got punted to a workqueue, we can have the
896 * application entering polling for a command before it gets
897 * issued. That app will hold the uring_lock for the duration
898 * of the poll right here, so we need to take a breather every
899 * now and then to ensure that the issue has a chance to add
900 * the poll to the issued list. Otherwise we can spin here
901 * forever, while the workqueue is stuck trying to acquire the
904 if (!(++iters & 7)) {
905 mutex_unlock(&ctx->uring_lock);
906 mutex_lock(&ctx->uring_lock);
909 if (*nr_events < min)
910 tmin = min - *nr_events;
912 ret = io_iopoll_getevents(ctx, nr_events, tmin);
916 } while (min && !*nr_events && !need_resched());
918 mutex_unlock(&ctx->uring_lock);
922 static void kiocb_end_write(struct kiocb *kiocb)
924 if (kiocb->ki_flags & IOCB_WRITE) {
925 struct inode *inode = file_inode(kiocb->ki_filp);
928 * Tell lockdep we inherited freeze protection from submission
931 if (S_ISREG(inode->i_mode))
932 __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
933 file_end_write(kiocb->ki_filp);
937 static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
939 struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
941 kiocb_end_write(kiocb);
943 if ((req->flags & REQ_F_LINK) && res != req->result)
944 req->flags |= REQ_F_FAIL_LINK;
945 io_cqring_add_event(req->ctx, req->user_data, res);
949 static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
951 struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
953 kiocb_end_write(kiocb);
955 if ((req->flags & REQ_F_LINK) && res != req->result)
956 req->flags |= REQ_F_FAIL_LINK;
959 req->flags |= REQ_F_IOPOLL_COMPLETED;
963 * After the iocb has been issued, it's safe to be found on the poll list.
964 * Adding the kiocb to the list AFTER submission ensures that we don't
965 * find it from a io_iopoll_getevents() thread before the issuer is done
966 * accessing the kiocb cookie.
968 static void io_iopoll_req_issued(struct io_kiocb *req)
970 struct io_ring_ctx *ctx = req->ctx;
973 * Track whether we have multiple files in our lists. This will impact
974 * how we do polling eventually, not spinning if we're on potentially
977 if (list_empty(&ctx->poll_list)) {
978 ctx->poll_multi_file = false;
979 } else if (!ctx->poll_multi_file) {
980 struct io_kiocb *list_req;
982 list_req = list_first_entry(&ctx->poll_list, struct io_kiocb,
984 if (list_req->rw.ki_filp != req->rw.ki_filp)
985 ctx->poll_multi_file = true;
989 * For fast devices, IO may have already completed. If it has, add
990 * it to the front so we find it first.
992 if (req->flags & REQ_F_IOPOLL_COMPLETED)
993 list_add(&req->list, &ctx->poll_list);
995 list_add_tail(&req->list, &ctx->poll_list);
998 static void io_file_put(struct io_submit_state *state)
1001 int diff = state->has_refs - state->used_refs;
1004 fput_many(state->file, diff);
1010 * Get as many references to a file as we have IOs left in this submission,
1011 * assuming most submissions are for one file, or at least that each file
1012 * has more than one submission.
1014 static struct file *io_file_get(struct io_submit_state *state, int fd)
1020 if (state->fd == fd) {
1027 state->file = fget_many(fd, state->ios_left);
1032 state->has_refs = state->ios_left;
1033 state->used_refs = 1;
1039 * If we tracked the file through the SCM inflight mechanism, we could support
1040 * any file. For now, just ensure that anything potentially problematic is done
1043 static bool io_file_supports_async(struct file *file)
1045 umode_t mode = file_inode(file)->i_mode;
1047 if (S_ISBLK(mode) || S_ISCHR(mode))
1049 if (S_ISREG(mode) && file->f_op != &io_uring_fops)
1055 static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
1056 bool force_nonblock)
1058 const struct io_uring_sqe *sqe = s->sqe;
1059 struct io_ring_ctx *ctx = req->ctx;
1060 struct kiocb *kiocb = &req->rw;
1067 if (force_nonblock && !io_file_supports_async(req->file))
1068 force_nonblock = false;
1070 kiocb->ki_pos = READ_ONCE(sqe->off);
1071 kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
1072 kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
1074 ioprio = READ_ONCE(sqe->ioprio);
1076 ret = ioprio_check_cap(ioprio);
1080 kiocb->ki_ioprio = ioprio;
1082 kiocb->ki_ioprio = get_current_ioprio();
1084 ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));
1088 /* don't allow async punt if RWF_NOWAIT was requested */
1089 if (kiocb->ki_flags & IOCB_NOWAIT)
1090 req->flags |= REQ_F_NOWAIT;
1093 kiocb->ki_flags |= IOCB_NOWAIT;
1095 if (ctx->flags & IORING_SETUP_IOPOLL) {
1096 if (!(kiocb->ki_flags & IOCB_DIRECT) ||
1097 !kiocb->ki_filp->f_op->iopoll)
1100 kiocb->ki_flags |= IOCB_HIPRI;
1101 kiocb->ki_complete = io_complete_rw_iopoll;
1103 if (kiocb->ki_flags & IOCB_HIPRI)
1105 kiocb->ki_complete = io_complete_rw;
1110 static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
1116 case -ERESTARTNOINTR:
1117 case -ERESTARTNOHAND:
1118 case -ERESTART_RESTARTBLOCK:
1120 * We can't just restart the syscall, since previously
1121 * submitted sqes may already be in progress. Just fail this
1127 kiocb->ki_complete(kiocb, ret, 0);
1131 static int io_import_fixed(struct io_ring_ctx *ctx, int rw,
1132 const struct io_uring_sqe *sqe,
1133 struct iov_iter *iter)
1135 size_t len = READ_ONCE(sqe->len);
1136 struct io_mapped_ubuf *imu;
1137 unsigned index, buf_index;
1141 /* attempt to use fixed buffers without having provided iovecs */
1142 if (unlikely(!ctx->user_bufs))
1145 buf_index = READ_ONCE(sqe->buf_index);
1146 if (unlikely(buf_index >= ctx->nr_user_bufs))
1149 index = array_index_nospec(buf_index, ctx->nr_user_bufs);
1150 imu = &ctx->user_bufs[index];
1151 buf_addr = READ_ONCE(sqe->addr);
1154 if (buf_addr + len < buf_addr)
1156 /* not inside the mapped region */
1157 if (buf_addr < imu->ubuf || buf_addr + len > imu->ubuf + imu->len)
1161 * May not be a start of buffer, set size appropriately
1162 * and advance us to the beginning.
1164 offset = buf_addr - imu->ubuf;
1165 iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);
1169 * Don't use iov_iter_advance() here, as it's really slow for
1170 * using the latter parts of a big fixed buffer - it iterates
1171 * over each segment manually. We can cheat a bit here, because
1174 * 1) it's a BVEC iter, we set it up
1175 * 2) all bvecs are PAGE_SIZE in size, except potentially the
1176 * first and last bvec
1178 * So just find our index, and adjust the iterator afterwards.
1179 * If the offset is within the first bvec (or the whole first
1180 * bvec, just use iov_iter_advance(). This makes it easier
1181 * since we can just skip the first segment, which may not
1182 * be PAGE_SIZE aligned.
1184 const struct bio_vec *bvec = imu->bvec;
1186 if (offset <= bvec->bv_len) {
1187 iov_iter_advance(iter, offset);
1189 unsigned long seg_skip;
1191 /* skip first vec */
1192 offset -= bvec->bv_len;
1193 seg_skip = 1 + (offset >> PAGE_SHIFT);
1195 iter->bvec = bvec + seg_skip;
1196 iter->nr_segs -= seg_skip;
1197 iter->count -= bvec->bv_len + offset;
1198 iter->iov_offset = offset & ~PAGE_MASK;
1205 static ssize_t io_import_iovec(struct io_ring_ctx *ctx, int rw,
1206 const struct sqe_submit *s, struct iovec **iovec,
1207 struct iov_iter *iter)
1209 const struct io_uring_sqe *sqe = s->sqe;
1210 void __user *buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
1211 size_t sqe_len = READ_ONCE(sqe->len);
1215 * We're reading ->opcode for the second time, but the first read
1216 * doesn't care whether it's _FIXED or not, so it doesn't matter
1217 * whether ->opcode changes concurrently. The first read does care
1218 * about whether it is a READ or a WRITE, so we don't trust this read
1219 * for that purpose and instead let the caller pass in the read/write
1222 opcode = READ_ONCE(sqe->opcode);
1223 if (opcode == IORING_OP_READ_FIXED ||
1224 opcode == IORING_OP_WRITE_FIXED) {
1225 ssize_t ret = io_import_fixed(ctx, rw, sqe, iter);
1233 #ifdef CONFIG_COMPAT
1235 return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
1239 return import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter);
1242 static inline bool io_should_merge(struct async_list *al, struct kiocb *kiocb)
1244 if (al->file == kiocb->ki_filp) {
1248 * Allow merging if we're anywhere in the range of the same
1249 * page. Generally this happens for sub-page reads or writes,
1250 * and it's beneficial to allow the first worker to bring the
1251 * page in and the piggy backed work can then work on the
1254 start = al->io_start & PAGE_MASK;
1255 end = (al->io_start + al->io_len + PAGE_SIZE - 1) & PAGE_MASK;
1256 if (kiocb->ki_pos >= start && kiocb->ki_pos <= end)
1265 * Make a note of the last file/offset/direction we punted to async
1266 * context. We'll use this information to see if we can piggy back a
1267 * sequential request onto the previous one, if it's still hasn't been
1268 * completed by the async worker.
1270 static void io_async_list_note(int rw, struct io_kiocb *req, size_t len)
1272 struct async_list *async_list = &req->ctx->pending_async[rw];
1273 struct kiocb *kiocb = &req->rw;
1274 struct file *filp = kiocb->ki_filp;
1276 if (io_should_merge(async_list, kiocb)) {
1277 unsigned long max_bytes;
1279 /* Use 8x RA size as a decent limiter for both reads/writes */
1280 max_bytes = filp->f_ra.ra_pages << (PAGE_SHIFT + 3);
1282 max_bytes = VM_READAHEAD_PAGES << (PAGE_SHIFT + 3);
1284 /* If max len are exceeded, reset the state */
1285 if (async_list->io_len + len <= max_bytes) {
1286 req->flags |= REQ_F_SEQ_PREV;
1287 async_list->io_len += len;
1289 async_list->file = NULL;
1293 /* New file? Reset state. */
1294 if (async_list->file != filp) {
1295 async_list->io_start = kiocb->ki_pos;
1296 async_list->io_len = len;
1297 async_list->file = filp;
1301 static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
1302 bool force_nonblock)
1304 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1305 struct kiocb *kiocb = &req->rw;
1306 struct iov_iter iter;
1309 ssize_t read_size, ret;
1311 ret = io_prep_rw(req, s, force_nonblock);
1314 file = kiocb->ki_filp;
1316 if (unlikely(!(file->f_mode & FMODE_READ)))
1318 if (unlikely(!file->f_op->read_iter))
1321 ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);
1326 if (req->flags & REQ_F_LINK)
1327 req->result = read_size;
1329 iov_count = iov_iter_count(&iter);
1330 ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_count);
1334 ret2 = call_read_iter(file, kiocb, &iter);
1336 * In case of a short read, punt to async. This can happen
1337 * if we have data partially cached. Alternatively we can
1338 * return the short read, in which case the application will
1339 * need to issue another SQE and wait for it. That SQE will
1340 * need async punt anyway, so it's more efficient to do it
1343 if (force_nonblock && ret2 > 0 && ret2 < read_size)
1345 /* Catch -EAGAIN return for forced non-blocking submission */
1346 if (!force_nonblock || ret2 != -EAGAIN) {
1347 io_rw_done(kiocb, ret2);
1350 * If ->needs_lock is true, we're already in async
1354 io_async_list_note(READ, req, iov_count);
1362 static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
1363 bool force_nonblock)
1365 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1366 struct kiocb *kiocb = &req->rw;
1367 struct iov_iter iter;
1372 ret = io_prep_rw(req, s, force_nonblock);
1376 file = kiocb->ki_filp;
1377 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1379 if (unlikely(!file->f_op->write_iter))
1382 ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);
1386 if (req->flags & REQ_F_LINK)
1389 iov_count = iov_iter_count(&iter);
1392 if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT)) {
1393 /* If ->needs_lock is true, we're already in async context. */
1395 io_async_list_note(WRITE, req, iov_count);
1399 ret = rw_verify_area(WRITE, file, &kiocb->ki_pos, iov_count);
1404 * Open-code file_start_write here to grab freeze protection,
1405 * which will be released by another thread in
1406 * io_complete_rw(). Fool lockdep by telling it the lock got
1407 * released so that it doesn't complain about the held lock when
1408 * we return to userspace.
1410 if (S_ISREG(file_inode(file)->i_mode)) {
1411 __sb_start_write(file_inode(file)->i_sb,
1412 SB_FREEZE_WRITE, true);
1413 __sb_writers_release(file_inode(file)->i_sb,
1416 kiocb->ki_flags |= IOCB_WRITE;
1418 ret2 = call_write_iter(file, kiocb, &iter);
1419 if (!force_nonblock || ret2 != -EAGAIN) {
1420 io_rw_done(kiocb, ret2);
1423 * If ->needs_lock is true, we're already in async
1427 io_async_list_note(WRITE, req, iov_count);
1437 * IORING_OP_NOP just posts a completion event, nothing else.
1439 static int io_nop(struct io_kiocb *req, u64 user_data)
1441 struct io_ring_ctx *ctx = req->ctx;
1444 if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
1447 io_cqring_add_event(ctx, user_data, err);
1452 static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
1454 struct io_ring_ctx *ctx = req->ctx;
1459 if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
1461 if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
1467 static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
1468 bool force_nonblock)
1470 loff_t sqe_off = READ_ONCE(sqe->off);
1471 loff_t sqe_len = READ_ONCE(sqe->len);
1472 loff_t end = sqe_off + sqe_len;
1473 unsigned fsync_flags;
1476 fsync_flags = READ_ONCE(sqe->fsync_flags);
1477 if (unlikely(fsync_flags & ~IORING_FSYNC_DATASYNC))
1480 ret = io_prep_fsync(req, sqe);
1484 /* fsync always requires a blocking context */
1488 ret = vfs_fsync_range(req->rw.ki_filp, sqe_off,
1489 end > 0 ? end : LLONG_MAX,
1490 fsync_flags & IORING_FSYNC_DATASYNC);
1492 if (ret < 0 && (req->flags & REQ_F_LINK))
1493 req->flags |= REQ_F_FAIL_LINK;
1494 io_cqring_add_event(req->ctx, sqe->user_data, ret);
1499 static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe)
1501 struct io_ring_ctx *ctx = req->ctx;
1507 if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
1509 if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
1515 static int io_sync_file_range(struct io_kiocb *req,
1516 const struct io_uring_sqe *sqe,
1517 bool force_nonblock)
1524 ret = io_prep_sfr(req, sqe);
1528 /* sync_file_range always requires a blocking context */
1532 sqe_off = READ_ONCE(sqe->off);
1533 sqe_len = READ_ONCE(sqe->len);
1534 flags = READ_ONCE(sqe->sync_range_flags);
1536 ret = sync_file_range(req->rw.ki_filp, sqe_off, sqe_len, flags);
1538 if (ret < 0 && (req->flags & REQ_F_LINK))
1539 req->flags |= REQ_F_FAIL_LINK;
1540 io_cqring_add_event(req->ctx, sqe->user_data, ret);
1545 #if defined(CONFIG_NET)
1546 static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
1547 bool force_nonblock,
1548 long (*fn)(struct socket *, struct user_msghdr __user *,
1551 struct socket *sock;
1554 if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
1557 sock = sock_from_file(req->file, &ret);
1559 struct user_msghdr __user *msg;
1562 flags = READ_ONCE(sqe->msg_flags);
1563 if (flags & MSG_DONTWAIT)
1564 req->flags |= REQ_F_NOWAIT;
1565 else if (force_nonblock)
1566 flags |= MSG_DONTWAIT;
1568 msg = (struct user_msghdr __user *) (unsigned long)
1569 READ_ONCE(sqe->addr);
1571 ret = fn(sock, msg, flags);
1572 if (force_nonblock && ret == -EAGAIN)
1576 io_cqring_add_event(req->ctx, sqe->user_data, ret);
1582 static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
1583 bool force_nonblock)
1585 #if defined(CONFIG_NET)
1586 return io_send_recvmsg(req, sqe, force_nonblock, __sys_sendmsg_sock);
1592 static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
1593 bool force_nonblock)
1595 #if defined(CONFIG_NET)
1596 return io_send_recvmsg(req, sqe, force_nonblock, __sys_recvmsg_sock);
1602 static void io_poll_remove_one(struct io_kiocb *req)
1604 struct io_poll_iocb *poll = &req->poll;
1606 spin_lock(&poll->head->lock);
1607 WRITE_ONCE(poll->canceled, true);
1608 if (!list_empty(&poll->wait.entry)) {
1609 list_del_init(&poll->wait.entry);
1610 io_queue_async_work(req->ctx, req);
1612 spin_unlock(&poll->head->lock);
1614 list_del_init(&req->list);
1617 static void io_poll_remove_all(struct io_ring_ctx *ctx)
1619 struct io_kiocb *req;
1621 spin_lock_irq(&ctx->completion_lock);
1622 while (!list_empty(&ctx->cancel_list)) {
1623 req = list_first_entry(&ctx->cancel_list, struct io_kiocb,list);
1624 io_poll_remove_one(req);
1626 spin_unlock_irq(&ctx->completion_lock);
1630 * Find a running poll command that matches one specified in sqe->addr,
1631 * and remove it if found.
1633 static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe)
1635 struct io_ring_ctx *ctx = req->ctx;
1636 struct io_kiocb *poll_req, *next;
1639 if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
1641 if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index ||
1645 spin_lock_irq(&ctx->completion_lock);
1646 list_for_each_entry_safe(poll_req, next, &ctx->cancel_list, list) {
1647 if (READ_ONCE(sqe->addr) == poll_req->user_data) {
1648 io_poll_remove_one(poll_req);
1653 spin_unlock_irq(&ctx->completion_lock);
1655 io_cqring_add_event(req->ctx, sqe->user_data, ret);
1660 static void io_poll_complete(struct io_ring_ctx *ctx, struct io_kiocb *req,
1663 req->poll.done = true;
1664 io_cqring_fill_event(ctx, req->user_data, mangle_poll(mask));
1665 io_commit_cqring(ctx);
1668 static void io_poll_complete_work(struct work_struct *work)
1670 struct io_kiocb *req = container_of(work, struct io_kiocb, work);
1671 struct io_poll_iocb *poll = &req->poll;
1672 struct poll_table_struct pt = { ._key = poll->events };
1673 struct io_ring_ctx *ctx = req->ctx;
1676 if (!READ_ONCE(poll->canceled))
1677 mask = vfs_poll(poll->file, &pt) & poll->events;
1680 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1681 * calling ->ki_cancel. We need the ctx_lock roundtrip here to
1682 * synchronize with them. In the cancellation case the list_del_init
1683 * itself is not actually needed, but harmless so we keep it in to
1684 * avoid further branches in the fast path.
1686 spin_lock_irq(&ctx->completion_lock);
1687 if (!mask && !READ_ONCE(poll->canceled)) {
1688 add_wait_queue(poll->head, &poll->wait);
1689 spin_unlock_irq(&ctx->completion_lock);
1692 list_del_init(&req->list);
1693 io_poll_complete(ctx, req, mask);
1694 spin_unlock_irq(&ctx->completion_lock);
1696 io_cqring_ev_posted(ctx);
1700 static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1703 struct io_poll_iocb *poll = container_of(wait, struct io_poll_iocb,
1705 struct io_kiocb *req = container_of(poll, struct io_kiocb, poll);
1706 struct io_ring_ctx *ctx = req->ctx;
1707 __poll_t mask = key_to_poll(key);
1708 unsigned long flags;
1710 /* for instances that support it check for an event match first: */
1711 if (mask && !(mask & poll->events))
1714 list_del_init(&poll->wait.entry);
1716 if (mask && spin_trylock_irqsave(&ctx->completion_lock, flags)) {
1717 list_del(&req->list);
1718 io_poll_complete(ctx, req, mask);
1719 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1721 io_cqring_ev_posted(ctx);
1724 io_queue_async_work(ctx, req);
1730 struct io_poll_table {
1731 struct poll_table_struct pt;
1732 struct io_kiocb *req;
1736 static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1737 struct poll_table_struct *p)
1739 struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);
1741 if (unlikely(pt->req->poll.head)) {
1742 pt->error = -EINVAL;
1747 pt->req->poll.head = head;
1748 add_wait_queue(head, &pt->req->poll.wait);
1751 static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
1753 struct io_poll_iocb *poll = &req->poll;
1754 struct io_ring_ctx *ctx = req->ctx;
1755 struct io_poll_table ipt;
1756 bool cancel = false;
1760 if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
1762 if (sqe->addr || sqe->ioprio || sqe->off || sqe->len || sqe->buf_index)
1767 req->submit.sqe = NULL;
1768 INIT_WORK(&req->work, io_poll_complete_work);
1769 events = READ_ONCE(sqe->poll_events);
1770 poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
1774 poll->canceled = false;
1776 ipt.pt._qproc = io_poll_queue_proc;
1777 ipt.pt._key = poll->events;
1779 ipt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1781 /* initialized the list so that we can do list_empty checks */
1782 INIT_LIST_HEAD(&poll->wait.entry);
1783 init_waitqueue_func_entry(&poll->wait, io_poll_wake);
1785 INIT_LIST_HEAD(&req->list);
1787 mask = vfs_poll(poll->file, &ipt.pt) & poll->events;
1789 spin_lock_irq(&ctx->completion_lock);
1790 if (likely(poll->head)) {
1791 spin_lock(&poll->head->lock);
1792 if (unlikely(list_empty(&poll->wait.entry))) {
1798 if (mask || ipt.error)
1799 list_del_init(&poll->wait.entry);
1801 WRITE_ONCE(poll->canceled, true);
1802 else if (!poll->done) /* actually waiting for an event */
1803 list_add_tail(&req->list, &ctx->cancel_list);
1804 spin_unlock(&poll->head->lock);
1806 if (mask) { /* no async, we'd stolen it */
1808 io_poll_complete(ctx, req, mask);
1810 spin_unlock_irq(&ctx->completion_lock);
1813 io_cqring_ev_posted(ctx);
1819 static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
1821 struct io_ring_ctx *ctx;
1822 struct io_kiocb *req;
1823 unsigned long flags;
1825 req = container_of(timer, struct io_kiocb, timeout.timer);
1827 atomic_inc(&ctx->cq_timeouts);
1829 spin_lock_irqsave(&ctx->completion_lock, flags);
1830 list_del(&req->list);
1832 io_cqring_fill_event(ctx, req->user_data, -ETIME);
1833 io_commit_cqring(ctx);
1834 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1836 io_cqring_ev_posted(ctx);
1839 return HRTIMER_NORESTART;
1842 static int io_timeout(struct io_kiocb *req, const struct io_uring_sqe *sqe)
1844 unsigned count, req_dist, tail_index;
1845 struct io_ring_ctx *ctx = req->ctx;
1846 struct list_head *entry;
1849 if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
1851 if (sqe->flags || sqe->ioprio || sqe->buf_index || sqe->timeout_flags ||
1854 if (copy_from_user(&ts, (void __user *) (unsigned long) sqe->addr,
1859 * sqe->off holds how many events that need to occur for this
1860 * timeout event to be satisfied.
1862 count = READ_ONCE(sqe->off);
1866 req->sequence = ctx->cached_sq_head + count - 1;
1867 req->flags |= REQ_F_TIMEOUT;
1870 * Insertion sort, ensuring the first entry in the list is always
1871 * the one we need first.
1873 tail_index = ctx->cached_cq_tail - ctx->rings->sq_dropped;
1874 req_dist = req->sequence - tail_index;
1875 spin_lock_irq(&ctx->completion_lock);
1876 list_for_each_prev(entry, &ctx->timeout_list) {
1877 struct io_kiocb *nxt = list_entry(entry, struct io_kiocb, list);
1880 dist = nxt->sequence - tail_index;
1881 if (req_dist >= dist)
1884 list_add(&req->list, entry);
1885 spin_unlock_irq(&ctx->completion_lock);
1887 hrtimer_init(&req->timeout.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1888 req->timeout.timer.function = io_timeout_fn;
1889 hrtimer_start(&req->timeout.timer, timespec_to_ktime(ts),
1894 static int io_req_defer(struct io_ring_ctx *ctx, struct io_kiocb *req,
1895 const struct io_uring_sqe *sqe)
1897 struct io_uring_sqe *sqe_copy;
1899 if (!io_sequence_defer(ctx, req) && list_empty(&ctx->defer_list))
1902 sqe_copy = kmalloc(sizeof(*sqe_copy), GFP_KERNEL);
1906 spin_lock_irq(&ctx->completion_lock);
1907 if (!io_sequence_defer(ctx, req) && list_empty(&ctx->defer_list)) {
1908 spin_unlock_irq(&ctx->completion_lock);
1913 memcpy(sqe_copy, sqe, sizeof(*sqe_copy));
1914 req->submit.sqe = sqe_copy;
1916 INIT_WORK(&req->work, io_sq_wq_submit_work);
1917 list_add_tail(&req->list, &ctx->defer_list);
1918 spin_unlock_irq(&ctx->completion_lock);
1919 return -EIOCBQUEUED;
1922 static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
1923 const struct sqe_submit *s, bool force_nonblock)
1927 req->user_data = READ_ONCE(s->sqe->user_data);
1929 if (unlikely(s->index >= ctx->sq_entries))
1932 opcode = READ_ONCE(s->sqe->opcode);
1935 ret = io_nop(req, req->user_data);
1937 case IORING_OP_READV:
1938 if (unlikely(s->sqe->buf_index))
1940 ret = io_read(req, s, force_nonblock);
1942 case IORING_OP_WRITEV:
1943 if (unlikely(s->sqe->buf_index))
1945 ret = io_write(req, s, force_nonblock);
1947 case IORING_OP_READ_FIXED:
1948 ret = io_read(req, s, force_nonblock);
1950 case IORING_OP_WRITE_FIXED:
1951 ret = io_write(req, s, force_nonblock);
1953 case IORING_OP_FSYNC:
1954 ret = io_fsync(req, s->sqe, force_nonblock);
1956 case IORING_OP_POLL_ADD:
1957 ret = io_poll_add(req, s->sqe);
1959 case IORING_OP_POLL_REMOVE:
1960 ret = io_poll_remove(req, s->sqe);
1962 case IORING_OP_SYNC_FILE_RANGE:
1963 ret = io_sync_file_range(req, s->sqe, force_nonblock);
1965 case IORING_OP_SENDMSG:
1966 ret = io_sendmsg(req, s->sqe, force_nonblock);
1968 case IORING_OP_RECVMSG:
1969 ret = io_recvmsg(req, s->sqe, force_nonblock);
1971 case IORING_OP_TIMEOUT:
1972 ret = io_timeout(req, s->sqe);
1982 if (ctx->flags & IORING_SETUP_IOPOLL) {
1983 if (req->result == -EAGAIN)
1986 /* workqueue context doesn't hold uring_lock, grab it now */
1988 mutex_lock(&ctx->uring_lock);
1989 io_iopoll_req_issued(req);
1991 mutex_unlock(&ctx->uring_lock);
1997 static struct async_list *io_async_list_from_sqe(struct io_ring_ctx *ctx,
1998 const struct io_uring_sqe *sqe)
2000 switch (sqe->opcode) {
2001 case IORING_OP_READV:
2002 case IORING_OP_READ_FIXED:
2003 return &ctx->pending_async[READ];
2004 case IORING_OP_WRITEV:
2005 case IORING_OP_WRITE_FIXED:
2006 return &ctx->pending_async[WRITE];
2012 static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
2014 u8 opcode = READ_ONCE(sqe->opcode);
2016 return !(opcode == IORING_OP_READ_FIXED ||
2017 opcode == IORING_OP_WRITE_FIXED);
2020 static void io_sq_wq_submit_work(struct work_struct *work)
2022 struct io_kiocb *req = container_of(work, struct io_kiocb, work);
2023 struct io_ring_ctx *ctx = req->ctx;
2024 struct mm_struct *cur_mm = NULL;
2025 struct async_list *async_list;
2026 LIST_HEAD(req_list);
2027 mm_segment_t old_fs;
2030 async_list = io_async_list_from_sqe(ctx, req->submit.sqe);
2033 struct sqe_submit *s = &req->submit;
2034 const struct io_uring_sqe *sqe = s->sqe;
2035 unsigned int flags = req->flags;
2037 /* Ensure we clear previously set non-block flag */
2038 req->rw.ki_flags &= ~IOCB_NOWAIT;
2041 if (io_sqe_needs_user(sqe) && !cur_mm) {
2042 if (!mmget_not_zero(ctx->sqo_mm)) {
2045 cur_mm = ctx->sqo_mm;
2053 s->has_user = cur_mm != NULL;
2054 s->needs_lock = true;
2056 ret = __io_submit_sqe(ctx, req, s, false);
2058 * We can get EAGAIN for polled IO even though
2059 * we're forcing a sync submission from here,
2060 * since we can't wait for request slots on the
2069 /* drop submission reference */
2073 io_cqring_add_event(ctx, sqe->user_data, ret);
2077 /* async context always use a copy of the sqe */
2080 /* req from defer and link list needn't decrease async cnt */
2081 if (flags & (REQ_F_IO_DRAINED | REQ_F_LINK_DONE))
2086 if (!list_empty(&req_list)) {
2087 req = list_first_entry(&req_list, struct io_kiocb,
2089 list_del(&req->list);
2092 if (list_empty(&async_list->list))
2096 spin_lock(&async_list->lock);
2097 if (list_empty(&async_list->list)) {
2098 spin_unlock(&async_list->lock);
2101 list_splice_init(&async_list->list, &req_list);
2102 spin_unlock(&async_list->lock);
2104 req = list_first_entry(&req_list, struct io_kiocb, list);
2105 list_del(&req->list);
2109 * Rare case of racing with a submitter. If we find the count has
2110 * dropped to zero AND we have pending work items, then restart
2111 * the processing. This is a tiny race window.
2114 ret = atomic_dec_return(&async_list->cnt);
2115 while (!ret && !list_empty(&async_list->list)) {
2116 spin_lock(&async_list->lock);
2117 atomic_inc(&async_list->cnt);
2118 list_splice_init(&async_list->list, &req_list);
2119 spin_unlock(&async_list->lock);
2121 if (!list_empty(&req_list)) {
2122 req = list_first_entry(&req_list,
2123 struct io_kiocb, list);
2124 list_del(&req->list);
2127 ret = atomic_dec_return(&async_list->cnt);
2140 * See if we can piggy back onto previously submitted work, that is still
2141 * running. We currently only allow this if the new request is sequential
2142 * to the previous one we punted.
2144 static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
2150 if (!(req->flags & REQ_F_SEQ_PREV))
2152 if (!atomic_read(&list->cnt))
2156 spin_lock(&list->lock);
2157 list_add_tail(&req->list, &list->list);
2159 * Ensure we see a simultaneous modification from io_sq_wq_submit_work()
2162 if (!atomic_read(&list->cnt)) {
2163 list_del_init(&req->list);
2166 spin_unlock(&list->lock);
2170 static bool io_op_needs_file(const struct io_uring_sqe *sqe)
2172 int op = READ_ONCE(sqe->opcode);
2176 case IORING_OP_POLL_REMOVE:
2183 static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
2184 struct io_submit_state *state, struct io_kiocb *req)
2189 flags = READ_ONCE(s->sqe->flags);
2190 fd = READ_ONCE(s->sqe->fd);
2192 if (flags & IOSQE_IO_DRAIN)
2193 req->flags |= REQ_F_IO_DRAIN;
2195 * All io need record the previous position, if LINK vs DARIN,
2196 * it can be used to mark the position of the first IO in the
2199 req->sequence = s->sequence;
2201 if (!io_op_needs_file(s->sqe))
2204 if (flags & IOSQE_FIXED_FILE) {
2205 if (unlikely(!ctx->user_files ||
2206 (unsigned) fd >= ctx->nr_user_files))
2208 req->file = ctx->user_files[fd];
2209 req->flags |= REQ_F_FIXED_FILE;
2211 if (s->needs_fixed_file)
2213 req->file = io_file_get(state, fd);
2214 if (unlikely(!req->file))
2221 static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
2222 struct sqe_submit *s, bool force_nonblock)
2226 ret = __io_submit_sqe(ctx, req, s, force_nonblock);
2227 if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) {
2228 struct io_uring_sqe *sqe_copy;
2230 sqe_copy = kmemdup(s->sqe, sizeof(*sqe_copy), GFP_KERNEL);
2232 struct async_list *list;
2235 memcpy(&req->submit, s, sizeof(*s));
2236 list = io_async_list_from_sqe(ctx, s->sqe);
2237 if (!io_add_to_prev_work(list, req)) {
2239 atomic_inc(&list->cnt);
2240 INIT_WORK(&req->work, io_sq_wq_submit_work);
2241 io_queue_async_work(ctx, req);
2245 * Queued up for async execution, worker will release
2246 * submit reference when the iocb is actually submitted.
2252 /* drop submission reference */
2255 /* and drop final reference, if we failed */
2257 io_cqring_add_event(ctx, req->user_data, ret);
2258 if (req->flags & REQ_F_LINK)
2259 req->flags |= REQ_F_FAIL_LINK;
2266 static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
2267 struct sqe_submit *s, bool force_nonblock)
2271 ret = io_req_defer(ctx, req, s->sqe);
2273 if (ret != -EIOCBQUEUED) {
2275 io_cqring_add_event(ctx, s->sqe->user_data, ret);
2280 return __io_queue_sqe(ctx, req, s, force_nonblock);
2283 static int io_queue_link_head(struct io_ring_ctx *ctx, struct io_kiocb *req,
2284 struct sqe_submit *s, struct io_kiocb *shadow,
2285 bool force_nonblock)
2288 int need_submit = false;
2291 return io_queue_sqe(ctx, req, s, force_nonblock);
2294 * Mark the first IO in link list as DRAIN, let all the following
2295 * IOs enter the defer list. all IO needs to be completed before link
2298 req->flags |= REQ_F_IO_DRAIN;
2299 ret = io_req_defer(ctx, req, s->sqe);
2301 if (ret != -EIOCBQUEUED) {
2303 io_cqring_add_event(ctx, s->sqe->user_data, ret);
2308 * If ret == 0 means that all IOs in front of link io are
2309 * running done. let's queue link head.
2314 /* Insert shadow req to defer_list, blocking next IOs */
2315 spin_lock_irq(&ctx->completion_lock);
2316 list_add_tail(&shadow->list, &ctx->defer_list);
2317 spin_unlock_irq(&ctx->completion_lock);
2320 return __io_queue_sqe(ctx, req, s, force_nonblock);
2325 #define SQE_VALID_FLAGS (IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK)
2327 static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
2328 struct io_submit_state *state, struct io_kiocb **link,
2329 bool force_nonblock)
2331 struct io_uring_sqe *sqe_copy;
2332 struct io_kiocb *req;
2335 /* enforce forwards compatibility on users */
2336 if (unlikely(s->sqe->flags & ~SQE_VALID_FLAGS)) {
2341 req = io_get_req(ctx, state);
2342 if (unlikely(!req)) {
2347 ret = io_req_set_file(ctx, s, state, req);
2348 if (unlikely(ret)) {
2352 io_cqring_add_event(ctx, s->sqe->user_data, ret);
2357 * If we already have a head request, queue this one for async
2358 * submittal once the head completes. If we don't have a head but
2359 * IOSQE_IO_LINK is set in the sqe, start a new head. This one will be
2360 * submitted sync once the chain is complete. If none of those
2361 * conditions are true (normal request), then just queue it.
2364 struct io_kiocb *prev = *link;
2366 sqe_copy = kmemdup(s->sqe, sizeof(*sqe_copy), GFP_KERNEL);
2373 memcpy(&req->submit, s, sizeof(*s));
2374 list_add_tail(&req->list, &prev->link_list);
2375 } else if (s->sqe->flags & IOSQE_IO_LINK) {
2376 req->flags |= REQ_F_LINK;
2378 memcpy(&req->submit, s, sizeof(*s));
2379 INIT_LIST_HEAD(&req->link_list);
2382 io_queue_sqe(ctx, req, s, force_nonblock);
2387 * Batched submission is done, ensure local IO is flushed out.
2389 static void io_submit_state_end(struct io_submit_state *state)
2391 blk_finish_plug(&state->plug);
2393 if (state->free_reqs)
2394 kmem_cache_free_bulk(req_cachep, state->free_reqs,
2395 &state->reqs[state->cur_req]);
2399 * Start submission side cache.
2401 static void io_submit_state_start(struct io_submit_state *state,
2402 struct io_ring_ctx *ctx, unsigned max_ios)
2404 blk_start_plug(&state->plug);
2405 state->free_reqs = 0;
2407 state->ios_left = max_ios;
2410 static void io_commit_sqring(struct io_ring_ctx *ctx)
2412 struct io_rings *rings = ctx->rings;
2414 if (ctx->cached_sq_head != READ_ONCE(rings->sq.head)) {
2416 * Ensure any loads from the SQEs are done at this point,
2417 * since once we write the new head, the application could
2418 * write new data to them.
2420 smp_store_release(&rings->sq.head, ctx->cached_sq_head);
2425 * Fetch an sqe, if one is available. Note that s->sqe will point to memory
2426 * that is mapped by userspace. This means that care needs to be taken to
2427 * ensure that reads are stable, as we cannot rely on userspace always
2428 * being a good citizen. If members of the sqe are validated and then later
2429 * used, it's important that those reads are done through READ_ONCE() to
2430 * prevent a re-load down the line.
2432 static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
2434 struct io_rings *rings = ctx->rings;
2435 u32 *sq_array = ctx->sq_array;
2439 * The cached sq head (or cq tail) serves two purposes:
2441 * 1) allows us to batch the cost of updating the user visible
2443 * 2) allows the kernel side to track the head on its own, even
2444 * though the application is the one updating it.
2446 head = ctx->cached_sq_head;
2447 /* make sure SQ entry isn't read before tail */
2448 if (head == smp_load_acquire(&rings->sq.tail))
2451 head = READ_ONCE(sq_array[head & ctx->sq_mask]);
2452 if (head < ctx->sq_entries) {
2454 s->sqe = &ctx->sq_sqes[head];
2455 s->sequence = ctx->cached_sq_head;
2456 ctx->cached_sq_head++;
2460 /* drop invalid entries */
2461 ctx->cached_sq_head++;
2462 rings->sq_dropped++;
2466 static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
2467 unsigned int nr, bool has_user, bool mm_fault)
2469 struct io_submit_state state, *statep = NULL;
2470 struct io_kiocb *link = NULL;
2471 struct io_kiocb *shadow_req = NULL;
2472 bool prev_was_link = false;
2473 int i, submitted = 0;
2475 if (nr > IO_PLUG_THRESHOLD) {
2476 io_submit_state_start(&state, ctx, nr);
2480 for (i = 0; i < nr; i++) {
2482 * If previous wasn't linked and we have a linked command,
2483 * that's the end of the chain. Submit the previous link.
2485 if (!prev_was_link && link) {
2486 io_queue_link_head(ctx, link, &link->submit, shadow_req,
2491 prev_was_link = (sqes[i].sqe->flags & IOSQE_IO_LINK) != 0;
2493 if (link && (sqes[i].sqe->flags & IOSQE_IO_DRAIN)) {
2495 shadow_req = io_get_req(ctx, NULL);
2496 if (unlikely(!shadow_req))
2498 shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
2499 refcount_dec(&shadow_req->refs);
2501 shadow_req->sequence = sqes[i].sequence;
2505 if (unlikely(mm_fault)) {
2506 io_cqring_add_event(ctx, sqes[i].sqe->user_data,
2509 sqes[i].has_user = has_user;
2510 sqes[i].needs_lock = true;
2511 sqes[i].needs_fixed_file = true;
2512 io_submit_sqe(ctx, &sqes[i], statep, &link, true);
2518 io_queue_link_head(ctx, link, &link->submit, shadow_req, true);
2520 io_submit_state_end(&state);
2525 static int io_sq_thread(void *data)
2527 struct sqe_submit sqes[IO_IOPOLL_BATCH];
2528 struct io_ring_ctx *ctx = data;
2529 struct mm_struct *cur_mm = NULL;
2530 mm_segment_t old_fs;
2533 unsigned long timeout;
2535 complete(&ctx->sqo_thread_started);
2540 timeout = inflight = 0;
2541 while (!kthread_should_park()) {
2542 bool all_fixed, mm_fault = false;
2546 unsigned nr_events = 0;
2548 if (ctx->flags & IORING_SETUP_IOPOLL) {
2549 io_iopoll_check(ctx, &nr_events, 0);
2552 * Normal IO, just pretend everything completed.
2553 * We don't have to poll completions for that.
2555 nr_events = inflight;
2558 inflight -= nr_events;
2560 timeout = jiffies + ctx->sq_thread_idle;
2563 if (!io_get_sqring(ctx, &sqes[0])) {
2565 * We're polling. If we're within the defined idle
2566 * period, then let us spin without work before going
2569 if (inflight || !time_after(jiffies, timeout)) {
2575 * Drop cur_mm before scheduling, we can't hold it for
2576 * long periods (or over schedule()). Do this before
2577 * adding ourselves to the waitqueue, as the unuse/drop
2586 prepare_to_wait(&ctx->sqo_wait, &wait,
2587 TASK_INTERRUPTIBLE);
2589 /* Tell userspace we may need a wakeup call */
2590 ctx->rings->sq_flags |= IORING_SQ_NEED_WAKEUP;
2591 /* make sure to read SQ tail after writing flags */
2594 if (!io_get_sqring(ctx, &sqes[0])) {
2595 if (kthread_should_park()) {
2596 finish_wait(&ctx->sqo_wait, &wait);
2599 if (signal_pending(current))
2600 flush_signals(current);
2602 finish_wait(&ctx->sqo_wait, &wait);
2604 ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
2607 finish_wait(&ctx->sqo_wait, &wait);
2609 ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
2615 if (all_fixed && io_sqe_needs_user(sqes[i].sqe))
2619 if (i == ARRAY_SIZE(sqes))
2621 } while (io_get_sqring(ctx, &sqes[i]));
2623 /* Unless all new commands are FIXED regions, grab mm */
2624 if (!all_fixed && !cur_mm) {
2625 mm_fault = !mmget_not_zero(ctx->sqo_mm);
2627 use_mm(ctx->sqo_mm);
2628 cur_mm = ctx->sqo_mm;
2632 inflight += io_submit_sqes(ctx, sqes, i, cur_mm != NULL,
2635 /* Commit SQ ring head once we've consumed all SQEs */
2636 io_commit_sqring(ctx);
2650 static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit,
2651 bool block_for_last)
2653 struct io_submit_state state, *statep = NULL;
2654 struct io_kiocb *link = NULL;
2655 struct io_kiocb *shadow_req = NULL;
2656 bool prev_was_link = false;
2659 if (to_submit > IO_PLUG_THRESHOLD) {
2660 io_submit_state_start(&state, ctx, to_submit);
2664 for (i = 0; i < to_submit; i++) {
2665 bool force_nonblock = true;
2666 struct sqe_submit s;
2668 if (!io_get_sqring(ctx, &s))
2672 * If previous wasn't linked and we have a linked command,
2673 * that's the end of the chain. Submit the previous link.
2675 if (!prev_was_link && link) {
2676 io_queue_link_head(ctx, link, &link->submit, shadow_req,
2681 prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
2683 if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
2685 shadow_req = io_get_req(ctx, NULL);
2686 if (unlikely(!shadow_req))
2688 shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
2689 refcount_dec(&shadow_req->refs);
2691 shadow_req->sequence = s.sequence;
2696 s.needs_lock = false;
2697 s.needs_fixed_file = false;
2701 * The caller will block for events after submit, submit the
2702 * last IO non-blocking. This is either the only IO it's
2703 * submitting, or it already submitted the previous ones. This
2704 * improves performance by avoiding an async punt that we don't
2707 if (block_for_last && submit == to_submit)
2708 force_nonblock = false;
2710 io_submit_sqe(ctx, &s, statep, &link, force_nonblock);
2712 io_commit_sqring(ctx);
2715 io_queue_link_head(ctx, link, &link->submit, shadow_req,
2718 io_submit_state_end(statep);
2724 * Wait until events become available, if we don't already have some. The
2725 * application must reap them itself, as they reside on the shared cq ring.
2727 static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
2728 const sigset_t __user *sig, size_t sigsz)
2730 struct io_rings *rings = ctx->rings;
2731 unsigned nr_timeouts;
2734 if (io_cqring_events(rings) >= min_events)
2738 #ifdef CONFIG_COMPAT
2739 if (in_compat_syscall())
2740 ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
2744 ret = set_user_sigmask(sig, sigsz);
2750 nr_timeouts = atomic_read(&ctx->cq_timeouts);
2752 * Return if we have enough events, or if a timeout occured since
2753 * we started waiting. For timeouts, we always want to return to
2756 ret = wait_event_interruptible(ctx->wait,
2757 io_cqring_events(rings) >= min_events ||
2758 atomic_read(&ctx->cq_timeouts) != nr_timeouts);
2759 restore_saved_sigmask_unless(ret == -ERESTARTSYS);
2760 if (ret == -ERESTARTSYS)
2763 return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
2766 static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
2768 #if defined(CONFIG_UNIX)
2769 if (ctx->ring_sock) {
2770 struct sock *sock = ctx->ring_sock->sk;
2771 struct sk_buff *skb;
2773 while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
2779 for (i = 0; i < ctx->nr_user_files; i++)
2780 fput(ctx->user_files[i]);
2784 static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
2786 if (!ctx->user_files)
2789 __io_sqe_files_unregister(ctx);
2790 kfree(ctx->user_files);
2791 ctx->user_files = NULL;
2792 ctx->nr_user_files = 0;
2796 static void io_sq_thread_stop(struct io_ring_ctx *ctx)
2798 if (ctx->sqo_thread) {
2799 wait_for_completion(&ctx->sqo_thread_started);
2801 * The park is a bit of a work-around, without it we get
2802 * warning spews on shutdown with SQPOLL set and affinity
2803 * set to a single CPU.
2805 kthread_park(ctx->sqo_thread);
2806 kthread_stop(ctx->sqo_thread);
2807 ctx->sqo_thread = NULL;
2811 static void io_finish_async(struct io_ring_ctx *ctx)
2815 io_sq_thread_stop(ctx);
2817 for (i = 0; i < ARRAY_SIZE(ctx->sqo_wq); i++) {
2818 if (ctx->sqo_wq[i]) {
2819 destroy_workqueue(ctx->sqo_wq[i]);
2820 ctx->sqo_wq[i] = NULL;
2825 #if defined(CONFIG_UNIX)
2826 static void io_destruct_skb(struct sk_buff *skb)
2828 struct io_ring_ctx *ctx = skb->sk->sk_user_data;
2830 io_finish_async(ctx);
2831 unix_destruct_scm(skb);
2835 * Ensure the UNIX gc is aware of our file set, so we are certain that
2836 * the io_uring can be safely unregistered on process exit, even if we have
2837 * loops in the file referencing.
2839 static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
2841 struct sock *sk = ctx->ring_sock->sk;
2842 struct scm_fp_list *fpl;
2843 struct sk_buff *skb;
2846 if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
2847 unsigned long inflight = ctx->user->unix_inflight + nr;
2849 if (inflight > task_rlimit(current, RLIMIT_NOFILE))
2853 fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
2857 skb = alloc_skb(0, GFP_KERNEL);
2864 skb->destructor = io_destruct_skb;
2866 fpl->user = get_uid(ctx->user);
2867 for (i = 0; i < nr; i++) {
2868 fpl->fp[i] = get_file(ctx->user_files[i + offset]);
2869 unix_inflight(fpl->user, fpl->fp[i]);
2872 fpl->max = fpl->count = nr;
2873 UNIXCB(skb).fp = fpl;
2874 refcount_add(skb->truesize, &sk->sk_wmem_alloc);
2875 skb_queue_head(&sk->sk_receive_queue, skb);
2877 for (i = 0; i < nr; i++)
2884 * If UNIX sockets are enabled, fd passing can cause a reference cycle which
2885 * causes regular reference counting to break down. We rely on the UNIX
2886 * garbage collection to take care of this problem for us.
2888 static int io_sqe_files_scm(struct io_ring_ctx *ctx)
2890 unsigned left, total;
2894 left = ctx->nr_user_files;
2896 unsigned this_files = min_t(unsigned, left, SCM_MAX_FD);
2898 ret = __io_sqe_files_scm(ctx, this_files, total);
2902 total += this_files;
2908 while (total < ctx->nr_user_files) {
2909 fput(ctx->user_files[total]);
2916 static int io_sqe_files_scm(struct io_ring_ctx *ctx)
2922 static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
2925 __s32 __user *fds = (__s32 __user *) arg;
2929 if (ctx->user_files)
2933 if (nr_args > IORING_MAX_FIXED_FILES)
2936 ctx->user_files = kcalloc(nr_args, sizeof(struct file *), GFP_KERNEL);
2937 if (!ctx->user_files)
2940 for (i = 0; i < nr_args; i++) {
2942 if (copy_from_user(&fd, &fds[i], sizeof(fd)))
2945 ctx->user_files[i] = fget(fd);
2948 if (!ctx->user_files[i])
2951 * Don't allow io_uring instances to be registered. If UNIX
2952 * isn't enabled, then this causes a reference cycle and this
2953 * instance can never get freed. If UNIX is enabled we'll
2954 * handle it just fine, but there's still no point in allowing
2955 * a ring fd as it doesn't support regular read/write anyway.
2957 if (ctx->user_files[i]->f_op == &io_uring_fops) {
2958 fput(ctx->user_files[i]);
2961 ctx->nr_user_files++;
2966 for (i = 0; i < ctx->nr_user_files; i++)
2967 fput(ctx->user_files[i]);
2969 kfree(ctx->user_files);
2970 ctx->user_files = NULL;
2971 ctx->nr_user_files = 0;
2975 ret = io_sqe_files_scm(ctx);
2977 io_sqe_files_unregister(ctx);
2982 static int io_sq_offload_start(struct io_ring_ctx *ctx,
2983 struct io_uring_params *p)
2987 init_waitqueue_head(&ctx->sqo_wait);
2988 mmgrab(current->mm);
2989 ctx->sqo_mm = current->mm;
2991 if (ctx->flags & IORING_SETUP_SQPOLL) {
2993 if (!capable(CAP_SYS_ADMIN))
2996 ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
2997 if (!ctx->sq_thread_idle)
2998 ctx->sq_thread_idle = HZ;
3000 if (p->flags & IORING_SETUP_SQ_AFF) {
3001 int cpu = p->sq_thread_cpu;
3004 if (cpu >= nr_cpu_ids)
3006 if (!cpu_online(cpu))
3009 ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread,
3013 ctx->sqo_thread = kthread_create(io_sq_thread, ctx,
3016 if (IS_ERR(ctx->sqo_thread)) {
3017 ret = PTR_ERR(ctx->sqo_thread);
3018 ctx->sqo_thread = NULL;
3021 wake_up_process(ctx->sqo_thread);
3022 } else if (p->flags & IORING_SETUP_SQ_AFF) {
3023 /* Can't have SQ_AFF without SQPOLL */
3028 /* Do QD, or 2 * CPUS, whatever is smallest */
3029 ctx->sqo_wq[0] = alloc_workqueue("io_ring-wq",
3030 WQ_UNBOUND | WQ_FREEZABLE,
3031 min(ctx->sq_entries - 1, 2 * num_online_cpus()));
3032 if (!ctx->sqo_wq[0]) {
3038 * This is for buffered writes, where we want to limit the parallelism
3039 * due to file locking in file systems. As "normal" buffered writes
3040 * should parellelize on writeout quite nicely, limit us to having 2
3041 * pending. This avoids massive contention on the inode when doing
3042 * buffered async writes.
3044 ctx->sqo_wq[1] = alloc_workqueue("io_ring-write-wq",
3045 WQ_UNBOUND | WQ_FREEZABLE, 2);
3046 if (!ctx->sqo_wq[1]) {
3053 io_finish_async(ctx);
3054 mmdrop(ctx->sqo_mm);
3059 static void io_unaccount_mem(struct user_struct *user, unsigned long nr_pages)
3061 atomic_long_sub(nr_pages, &user->locked_vm);
3064 static int io_account_mem(struct user_struct *user, unsigned long nr_pages)
3066 unsigned long page_limit, cur_pages, new_pages;
3068 /* Don't allow more pages than we can safely lock */
3069 page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
3072 cur_pages = atomic_long_read(&user->locked_vm);
3073 new_pages = cur_pages + nr_pages;
3074 if (new_pages > page_limit)
3076 } while (atomic_long_cmpxchg(&user->locked_vm, cur_pages,
3077 new_pages) != cur_pages);
3082 static void io_mem_free(void *ptr)
3089 page = virt_to_head_page(ptr);
3090 if (put_page_testzero(page))
3091 free_compound_page(page);
3094 static void *io_mem_alloc(size_t size)
3096 gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP |
3099 return (void *) __get_free_pages(gfp_flags, get_order(size));
3102 static unsigned long rings_size(unsigned sq_entries, unsigned cq_entries,
3105 struct io_rings *rings;
3106 size_t off, sq_array_size;
3108 off = struct_size(rings, cqes, cq_entries);
3109 if (off == SIZE_MAX)
3113 off = ALIGN(off, SMP_CACHE_BYTES);
3118 sq_array_size = array_size(sizeof(u32), sq_entries);
3119 if (sq_array_size == SIZE_MAX)
3122 if (check_add_overflow(off, sq_array_size, &off))
3131 static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries)
3135 pages = (size_t)1 << get_order(
3136 rings_size(sq_entries, cq_entries, NULL));
3137 pages += (size_t)1 << get_order(
3138 array_size(sizeof(struct io_uring_sqe), sq_entries));
3143 static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
3147 if (!ctx->user_bufs)
3150 for (i = 0; i < ctx->nr_user_bufs; i++) {
3151 struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
3153 for (j = 0; j < imu->nr_bvecs; j++)
3154 put_user_page(imu->bvec[j].bv_page);
3156 if (ctx->account_mem)
3157 io_unaccount_mem(ctx->user, imu->nr_bvecs);
3162 kfree(ctx->user_bufs);
3163 ctx->user_bufs = NULL;
3164 ctx->nr_user_bufs = 0;
3168 static int io_copy_iov(struct io_ring_ctx *ctx, struct iovec *dst,
3169 void __user *arg, unsigned index)
3171 struct iovec __user *src;
3173 #ifdef CONFIG_COMPAT
3175 struct compat_iovec __user *ciovs;
3176 struct compat_iovec ciov;
3178 ciovs = (struct compat_iovec __user *) arg;
3179 if (copy_from_user(&ciov, &ciovs[index], sizeof(ciov)))
3182 dst->iov_base = (void __user *) (unsigned long) ciov.iov_base;
3183 dst->iov_len = ciov.iov_len;
3187 src = (struct iovec __user *) arg;
3188 if (copy_from_user(dst, &src[index], sizeof(*dst)))
3193 static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
3196 struct vm_area_struct **vmas = NULL;
3197 struct page **pages = NULL;
3198 int i, j, got_pages = 0;
3203 if (!nr_args || nr_args > UIO_MAXIOV)
3206 ctx->user_bufs = kcalloc(nr_args, sizeof(struct io_mapped_ubuf),
3208 if (!ctx->user_bufs)
3211 for (i = 0; i < nr_args; i++) {
3212 struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
3213 unsigned long off, start, end, ubuf;
3218 ret = io_copy_iov(ctx, &iov, arg, i);
3223 * Don't impose further limits on the size and buffer
3224 * constraints here, we'll -EINVAL later when IO is
3225 * submitted if they are wrong.
3228 if (!iov.iov_base || !iov.iov_len)
3231 /* arbitrary limit, but we need something */
3232 if (iov.iov_len > SZ_1G)
3235 ubuf = (unsigned long) iov.iov_base;
3236 end = (ubuf + iov.iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
3237 start = ubuf >> PAGE_SHIFT;
3238 nr_pages = end - start;
3240 if (ctx->account_mem) {
3241 ret = io_account_mem(ctx->user, nr_pages);
3247 if (!pages || nr_pages > got_pages) {
3250 pages = kvmalloc_array(nr_pages, sizeof(struct page *),
3252 vmas = kvmalloc_array(nr_pages,
3253 sizeof(struct vm_area_struct *),
3255 if (!pages || !vmas) {
3257 if (ctx->account_mem)
3258 io_unaccount_mem(ctx->user, nr_pages);
3261 got_pages = nr_pages;
3264 imu->bvec = kvmalloc_array(nr_pages, sizeof(struct bio_vec),
3268 if (ctx->account_mem)
3269 io_unaccount_mem(ctx->user, nr_pages);
3274 down_read(¤t->mm->mmap_sem);
3275 pret = get_user_pages(ubuf, nr_pages,
3276 FOLL_WRITE | FOLL_LONGTERM,
3278 if (pret == nr_pages) {
3279 /* don't support file backed memory */
3280 for (j = 0; j < nr_pages; j++) {
3281 struct vm_area_struct *vma = vmas[j];
3284 !is_file_hugepages(vma->vm_file)) {
3290 ret = pret < 0 ? pret : -EFAULT;
3292 up_read(¤t->mm->mmap_sem);
3295 * if we did partial map, or found file backed vmas,
3296 * release any pages we did get
3299 put_user_pages(pages, pret);
3300 if (ctx->account_mem)
3301 io_unaccount_mem(ctx->user, nr_pages);
3306 off = ubuf & ~PAGE_MASK;
3308 for (j = 0; j < nr_pages; j++) {
3311 vec_len = min_t(size_t, size, PAGE_SIZE - off);
3312 imu->bvec[j].bv_page = pages[j];
3313 imu->bvec[j].bv_len = vec_len;
3314 imu->bvec[j].bv_offset = off;
3318 /* store original address for later verification */
3320 imu->len = iov.iov_len;
3321 imu->nr_bvecs = nr_pages;
3323 ctx->nr_user_bufs++;
3331 io_sqe_buffer_unregister(ctx);
3335 static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg)
3337 __s32 __user *fds = arg;
3343 if (copy_from_user(&fd, fds, sizeof(*fds)))
3346 ctx->cq_ev_fd = eventfd_ctx_fdget(fd);
3347 if (IS_ERR(ctx->cq_ev_fd)) {
3348 int ret = PTR_ERR(ctx->cq_ev_fd);
3349 ctx->cq_ev_fd = NULL;
3356 static int io_eventfd_unregister(struct io_ring_ctx *ctx)
3358 if (ctx->cq_ev_fd) {
3359 eventfd_ctx_put(ctx->cq_ev_fd);
3360 ctx->cq_ev_fd = NULL;
3367 static void io_ring_ctx_free(struct io_ring_ctx *ctx)
3369 io_finish_async(ctx);
3371 mmdrop(ctx->sqo_mm);
3373 io_iopoll_reap_events(ctx);
3374 io_sqe_buffer_unregister(ctx);
3375 io_sqe_files_unregister(ctx);
3376 io_eventfd_unregister(ctx);
3378 #if defined(CONFIG_UNIX)
3379 if (ctx->ring_sock) {
3380 ctx->ring_sock->file = NULL; /* so that iput() is called */
3381 sock_release(ctx->ring_sock);
3385 io_mem_free(ctx->rings);
3386 io_mem_free(ctx->sq_sqes);
3388 percpu_ref_exit(&ctx->refs);
3389 if (ctx->account_mem)
3390 io_unaccount_mem(ctx->user,
3391 ring_pages(ctx->sq_entries, ctx->cq_entries));
3392 free_uid(ctx->user);
3396 static __poll_t io_uring_poll(struct file *file, poll_table *wait)
3398 struct io_ring_ctx *ctx = file->private_data;
3401 poll_wait(file, &ctx->cq_wait, wait);
3403 * synchronizes with barrier from wq_has_sleeper call in
3407 if (READ_ONCE(ctx->rings->sq.tail) - ctx->cached_sq_head !=
3408 ctx->rings->sq_ring_entries)
3409 mask |= EPOLLOUT | EPOLLWRNORM;
3410 if (READ_ONCE(ctx->rings->sq.head) != ctx->cached_cq_tail)
3411 mask |= EPOLLIN | EPOLLRDNORM;
3416 static int io_uring_fasync(int fd, struct file *file, int on)
3418 struct io_ring_ctx *ctx = file->private_data;
3420 return fasync_helper(fd, file, on, &ctx->cq_fasync);
3423 static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
3425 mutex_lock(&ctx->uring_lock);
3426 percpu_ref_kill(&ctx->refs);
3427 mutex_unlock(&ctx->uring_lock);
3429 io_kill_timeouts(ctx);
3430 io_poll_remove_all(ctx);
3431 io_iopoll_reap_events(ctx);
3432 wait_for_completion(&ctx->ctx_done);
3433 io_ring_ctx_free(ctx);
3436 static int io_uring_release(struct inode *inode, struct file *file)
3438 struct io_ring_ctx *ctx = file->private_data;
3440 file->private_data = NULL;
3441 io_ring_ctx_wait_and_kill(ctx);
3445 static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
3447 loff_t offset = (loff_t) vma->vm_pgoff << PAGE_SHIFT;
3448 unsigned long sz = vma->vm_end - vma->vm_start;
3449 struct io_ring_ctx *ctx = file->private_data;
3455 case IORING_OFF_SQ_RING:
3456 case IORING_OFF_CQ_RING:
3459 case IORING_OFF_SQES:
3466 page = virt_to_head_page(ptr);
3467 if (sz > (PAGE_SIZE << compound_order(page)))
3470 pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
3471 return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
3474 SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
3475 u32, min_complete, u32, flags, const sigset_t __user *, sig,
3478 struct io_ring_ctx *ctx;
3483 if (flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP))
3491 if (f.file->f_op != &io_uring_fops)
3495 ctx = f.file->private_data;
3496 if (!percpu_ref_tryget(&ctx->refs))
3500 * For SQ polling, the thread will do all submissions and completions.
3501 * Just return the requested submit count, and wake the thread if
3505 if (ctx->flags & IORING_SETUP_SQPOLL) {
3506 if (flags & IORING_ENTER_SQ_WAKEUP)
3507 wake_up(&ctx->sqo_wait);
3508 submitted = to_submit;
3509 } else if (to_submit) {
3510 bool block_for_last = false;
3512 to_submit = min(to_submit, ctx->sq_entries);
3515 * Allow last submission to block in a series, IFF the caller
3516 * asked to wait for events and we don't currently have
3517 * enough. This potentially avoids an async punt.
3519 if (to_submit == min_complete &&
3520 io_cqring_events(ctx->rings) < min_complete)
3521 block_for_last = true;
3523 mutex_lock(&ctx->uring_lock);
3524 submitted = io_ring_submit(ctx, to_submit, block_for_last);
3525 mutex_unlock(&ctx->uring_lock);
3527 if (flags & IORING_ENTER_GETEVENTS) {
3528 unsigned nr_events = 0;
3530 min_complete = min(min_complete, ctx->cq_entries);
3532 if (ctx->flags & IORING_SETUP_IOPOLL) {
3533 ret = io_iopoll_check(ctx, &nr_events, min_complete);
3535 ret = io_cqring_wait(ctx, min_complete, sig, sigsz);
3539 io_ring_drop_ctx_refs(ctx, 1);
3542 return submitted ? submitted : ret;
3545 static const struct file_operations io_uring_fops = {
3546 .release = io_uring_release,
3547 .mmap = io_uring_mmap,
3548 .poll = io_uring_poll,
3549 .fasync = io_uring_fasync,
3552 static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
3553 struct io_uring_params *p)
3555 struct io_rings *rings;
3556 size_t size, sq_array_offset;
3558 size = rings_size(p->sq_entries, p->cq_entries, &sq_array_offset);
3559 if (size == SIZE_MAX)
3562 rings = io_mem_alloc(size);
3567 ctx->sq_array = (u32 *)((char *)rings + sq_array_offset);
3568 rings->sq_ring_mask = p->sq_entries - 1;
3569 rings->cq_ring_mask = p->cq_entries - 1;
3570 rings->sq_ring_entries = p->sq_entries;
3571 rings->cq_ring_entries = p->cq_entries;
3572 ctx->sq_mask = rings->sq_ring_mask;
3573 ctx->cq_mask = rings->cq_ring_mask;
3574 ctx->sq_entries = rings->sq_ring_entries;
3575 ctx->cq_entries = rings->cq_ring_entries;
3577 size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
3578 if (size == SIZE_MAX)
3581 ctx->sq_sqes = io_mem_alloc(size);
3589 * Allocate an anonymous fd, this is what constitutes the application
3590 * visible backing of an io_uring instance. The application mmaps this
3591 * fd to gain access to the SQ/CQ ring details. If UNIX sockets are enabled,
3592 * we have to tie this fd to a socket for file garbage collection purposes.
3594 static int io_uring_get_fd(struct io_ring_ctx *ctx)
3599 #if defined(CONFIG_UNIX)
3600 ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
3606 ret = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
3610 file = anon_inode_getfile("[io_uring]", &io_uring_fops, ctx,
3611 O_RDWR | O_CLOEXEC);
3614 ret = PTR_ERR(file);
3618 #if defined(CONFIG_UNIX)
3619 ctx->ring_sock->file = file;
3620 ctx->ring_sock->sk->sk_user_data = ctx;
3622 fd_install(ret, file);
3625 #if defined(CONFIG_UNIX)
3626 sock_release(ctx->ring_sock);
3627 ctx->ring_sock = NULL;
3632 static int io_uring_create(unsigned entries, struct io_uring_params *p)
3634 struct user_struct *user = NULL;
3635 struct io_ring_ctx *ctx;
3639 if (!entries || entries > IORING_MAX_ENTRIES)
3643 * Use twice as many entries for the CQ ring. It's possible for the
3644 * application to drive a higher depth than the size of the SQ ring,
3645 * since the sqes are only used at submission time. This allows for
3646 * some flexibility in overcommitting a bit.
3648 p->sq_entries = roundup_pow_of_two(entries);
3649 p->cq_entries = 2 * p->sq_entries;
3651 user = get_uid(current_user());
3652 account_mem = !capable(CAP_IPC_LOCK);
3655 ret = io_account_mem(user,
3656 ring_pages(p->sq_entries, p->cq_entries));
3663 ctx = io_ring_ctx_alloc(p);
3666 io_unaccount_mem(user, ring_pages(p->sq_entries,
3671 ctx->compat = in_compat_syscall();
3672 ctx->account_mem = account_mem;
3675 ret = io_allocate_scq_urings(ctx, p);
3679 ret = io_sq_offload_start(ctx, p);
3683 ret = io_uring_get_fd(ctx);
3687 memset(&p->sq_off, 0, sizeof(p->sq_off));
3688 p->sq_off.head = offsetof(struct io_rings, sq.head);
3689 p->sq_off.tail = offsetof(struct io_rings, sq.tail);
3690 p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
3691 p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
3692 p->sq_off.flags = offsetof(struct io_rings, sq_flags);
3693 p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
3694 p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
3696 memset(&p->cq_off, 0, sizeof(p->cq_off));
3697 p->cq_off.head = offsetof(struct io_rings, cq.head);
3698 p->cq_off.tail = offsetof(struct io_rings, cq.tail);
3699 p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
3700 p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
3701 p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
3702 p->cq_off.cqes = offsetof(struct io_rings, cqes);
3704 p->features = IORING_FEAT_SINGLE_MMAP;
3707 io_ring_ctx_wait_and_kill(ctx);
3712 * Sets up an aio uring context, and returns the fd. Applications asks for a
3713 * ring size, we return the actual sq/cq ring sizes (among other things) in the
3714 * params structure passed in.
3716 static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
3718 struct io_uring_params p;
3722 if (copy_from_user(&p, params, sizeof(p)))
3724 for (i = 0; i < ARRAY_SIZE(p.resv); i++) {
3729 if (p.flags & ~(IORING_SETUP_IOPOLL | IORING_SETUP_SQPOLL |
3730 IORING_SETUP_SQ_AFF))
3733 ret = io_uring_create(entries, &p);
3737 if (copy_to_user(params, &p, sizeof(p)))
3743 SYSCALL_DEFINE2(io_uring_setup, u32, entries,
3744 struct io_uring_params __user *, params)
3746 return io_uring_setup(entries, params);
3749 static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
3750 void __user *arg, unsigned nr_args)
3751 __releases(ctx->uring_lock)
3752 __acquires(ctx->uring_lock)
3757 * We're inside the ring mutex, if the ref is already dying, then
3758 * someone else killed the ctx or is already going through
3759 * io_uring_register().
3761 if (percpu_ref_is_dying(&ctx->refs))
3764 percpu_ref_kill(&ctx->refs);
3767 * Drop uring mutex before waiting for references to exit. If another
3768 * thread is currently inside io_uring_enter() it might need to grab
3769 * the uring_lock to make progress. If we hold it here across the drain
3770 * wait, then we can deadlock. It's safe to drop the mutex here, since
3771 * no new references will come in after we've killed the percpu ref.
3773 mutex_unlock(&ctx->uring_lock);
3774 wait_for_completion(&ctx->ctx_done);
3775 mutex_lock(&ctx->uring_lock);
3778 case IORING_REGISTER_BUFFERS:
3779 ret = io_sqe_buffer_register(ctx, arg, nr_args);
3781 case IORING_UNREGISTER_BUFFERS:
3785 ret = io_sqe_buffer_unregister(ctx);
3787 case IORING_REGISTER_FILES:
3788 ret = io_sqe_files_register(ctx, arg, nr_args);
3790 case IORING_UNREGISTER_FILES:
3794 ret = io_sqe_files_unregister(ctx);
3796 case IORING_REGISTER_EVENTFD:
3800 ret = io_eventfd_register(ctx, arg);
3802 case IORING_UNREGISTER_EVENTFD:
3806 ret = io_eventfd_unregister(ctx);
3813 /* bring the ctx back to life */
3814 reinit_completion(&ctx->ctx_done);
3815 percpu_ref_reinit(&ctx->refs);
3819 SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
3820 void __user *, arg, unsigned int, nr_args)
3822 struct io_ring_ctx *ctx;
3831 if (f.file->f_op != &io_uring_fops)
3834 ctx = f.file->private_data;
3836 mutex_lock(&ctx->uring_lock);
3837 ret = __io_uring_register(ctx, opcode, arg, nr_args);
3838 mutex_unlock(&ctx->uring_lock);
3844 static int __init io_uring_init(void)
3846 req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
3849 __initcall(io_uring_init);