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 4096
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 offset
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 and the application controls tail.
102 * Bitmask to apply to head and tail offsets (constant, equals
106 /* Ring size (constant, power of 2) */
109 * Number of invalid entries dropped by the kernel due to
110 * invalid index stored in array
112 * Written by the kernel, shouldn't be modified by the
113 * application (i.e. get number of "new events" by comparing to
116 * After a new SQ head value was read by the application this
117 * counter includes all submissions that were dropped reaching
118 * the new SQ head (and possibly more).
124 * Written by the kernel, shouldn't be modified by the
127 * The application needs a full memory barrier before checking
128 * for IORING_SQ_NEED_WAKEUP after updating the sq tail.
132 * Ring buffer of indices into array of io_uring_sqe, which is
133 * mmapped by the application using the IORING_OFF_SQES offset.
135 * This indirection could e.g. be used to assign fixed
136 * io_uring_sqe entries to operations and only submit them to
137 * the queue when needed.
139 * The kernel modifies neither the indices array nor the entries
146 * This data is shared with the application through the mmap at offset
147 * IORING_OFF_CQ_RING.
149 * The offsets to the member fields are published through struct
150 * io_cqring_offsets when calling io_uring_setup.
154 * Head and tail offsets into the ring; the offsets need to be
155 * masked to get valid indices.
157 * The application controls head and the kernel tail.
161 * Bitmask to apply to head and tail offsets (constant, equals
165 /* Ring size (constant, power of 2) */
168 * Number of completion events lost because the queue was full;
169 * this should be avoided by the application by making sure
170 * there are not more requests pending thatn there is space in
171 * the completion queue.
173 * Written by the kernel, shouldn't be modified by the
174 * application (i.e. get number of "new events" by comparing to
177 * As completion events come in out of order this counter is not
178 * ordered with any other data.
182 * Ring buffer of completion events.
184 * The kernel writes completion events fresh every time they are
185 * produced, so the application is allowed to modify pending
188 struct io_uring_cqe cqes
[];
191 struct io_mapped_ubuf
{
194 struct bio_vec
*bvec
;
195 unsigned int nr_bvecs
;
201 struct list_head list
;
210 struct percpu_ref refs
;
211 } ____cacheline_aligned_in_smp
;
219 struct io_sq_ring
*sq_ring
;
220 unsigned cached_sq_head
;
223 unsigned sq_thread_idle
;
224 struct io_uring_sqe
*sq_sqes
;
225 } ____cacheline_aligned_in_smp
;
228 struct workqueue_struct
*sqo_wq
;
229 struct task_struct
*sqo_thread
; /* if using sq thread polling */
230 struct mm_struct
*sqo_mm
;
231 wait_queue_head_t sqo_wait
;
236 struct io_cq_ring
*cq_ring
;
237 unsigned cached_cq_tail
;
240 struct wait_queue_head cq_wait
;
241 struct fasync_struct
*cq_fasync
;
242 } ____cacheline_aligned_in_smp
;
245 * If used, fixed file set. Writers must ensure that ->refs is dead,
246 * readers must ensure that ->refs is alive as long as the file* is
247 * used. Only updated through io_uring_register(2).
249 struct file
**user_files
;
250 unsigned nr_user_files
;
252 /* if used, fixed mapped user buffers */
253 unsigned nr_user_bufs
;
254 struct io_mapped_ubuf
*user_bufs
;
256 struct user_struct
*user
;
258 struct completion ctx_done
;
261 struct mutex uring_lock
;
262 wait_queue_head_t wait
;
263 } ____cacheline_aligned_in_smp
;
266 spinlock_t completion_lock
;
267 bool poll_multi_file
;
269 * ->poll_list is protected by the ctx->uring_lock for
270 * io_uring instances that don't use IORING_SETUP_SQPOLL.
271 * For SQPOLL, only the single threaded io_sq_thread() will
272 * manipulate the list, hence no extra locking is needed there.
274 struct list_head poll_list
;
275 struct list_head cancel_list
;
276 } ____cacheline_aligned_in_smp
;
278 struct async_list pending_async
[2];
280 #if defined(CONFIG_UNIX)
281 struct socket
*ring_sock
;
286 const struct io_uring_sqe
*sqe
;
287 unsigned short index
;
290 bool needs_fixed_file
;
294 * First field must be the file pointer in all the
295 * iocb unions! See also 'struct kiocb' in <linux/fs.h>
297 struct io_poll_iocb
{
299 struct wait_queue_head
*head
;
303 struct wait_queue_entry wait
;
307 * NOTE! Each of the iocb union members has the file pointer
308 * as the first entry in their struct definition. So you can
309 * access the file pointer through any of the sub-structs,
310 * or directly as just 'ki_filp' in this struct.
316 struct io_poll_iocb poll
;
319 struct sqe_submit submit
;
321 struct io_ring_ctx
*ctx
;
322 struct list_head list
;
325 #define REQ_F_NOWAIT 1 /* must not punt to workers */
326 #define REQ_F_IOPOLL_COMPLETED 2 /* polled IO has completed */
327 #define REQ_F_FIXED_FILE 4 /* ctx owns file */
328 #define REQ_F_SEQ_PREV 8 /* sequential with previous */
329 #define REQ_F_PREPPED 16 /* prep already done */
333 struct work_struct work
;
336 #define IO_PLUG_THRESHOLD 2
337 #define IO_IOPOLL_BATCH 8
339 struct io_submit_state
{
340 struct blk_plug plug
;
343 * io_kiocb alloc cache
345 void *reqs
[IO_IOPOLL_BATCH
];
346 unsigned int free_reqs
;
347 unsigned int cur_req
;
350 * File reference cache
354 unsigned int has_refs
;
355 unsigned int used_refs
;
356 unsigned int ios_left
;
359 static struct kmem_cache
*req_cachep
;
361 static const struct file_operations io_uring_fops
;
363 struct sock
*io_uring_get_socket(struct file
*file
)
365 #if defined(CONFIG_UNIX)
366 if (file
->f_op
== &io_uring_fops
) {
367 struct io_ring_ctx
*ctx
= file
->private_data
;
369 return ctx
->ring_sock
->sk
;
374 EXPORT_SYMBOL(io_uring_get_socket
);
376 static void io_ring_ctx_ref_free(struct percpu_ref
*ref
)
378 struct io_ring_ctx
*ctx
= container_of(ref
, struct io_ring_ctx
, refs
);
380 complete(&ctx
->ctx_done
);
383 static struct io_ring_ctx
*io_ring_ctx_alloc(struct io_uring_params
*p
)
385 struct io_ring_ctx
*ctx
;
388 ctx
= kzalloc(sizeof(*ctx
), GFP_KERNEL
);
392 if (percpu_ref_init(&ctx
->refs
, io_ring_ctx_ref_free
, 0, GFP_KERNEL
)) {
397 ctx
->flags
= p
->flags
;
398 init_waitqueue_head(&ctx
->cq_wait
);
399 init_completion(&ctx
->ctx_done
);
400 mutex_init(&ctx
->uring_lock
);
401 init_waitqueue_head(&ctx
->wait
);
402 for (i
= 0; i
< ARRAY_SIZE(ctx
->pending_async
); i
++) {
403 spin_lock_init(&ctx
->pending_async
[i
].lock
);
404 INIT_LIST_HEAD(&ctx
->pending_async
[i
].list
);
405 atomic_set(&ctx
->pending_async
[i
].cnt
, 0);
407 spin_lock_init(&ctx
->completion_lock
);
408 INIT_LIST_HEAD(&ctx
->poll_list
);
409 INIT_LIST_HEAD(&ctx
->cancel_list
);
413 static void io_commit_cqring(struct io_ring_ctx
*ctx
)
415 struct io_cq_ring
*ring
= ctx
->cq_ring
;
417 if (ctx
->cached_cq_tail
!= READ_ONCE(ring
->r
.tail
)) {
418 /* order cqe stores with ring update */
419 smp_store_release(&ring
->r
.tail
, ctx
->cached_cq_tail
);
421 if (wq_has_sleeper(&ctx
->cq_wait
)) {
422 wake_up_interruptible(&ctx
->cq_wait
);
423 kill_fasync(&ctx
->cq_fasync
, SIGIO
, POLL_IN
);
428 static struct io_uring_cqe
*io_get_cqring(struct io_ring_ctx
*ctx
)
430 struct io_cq_ring
*ring
= ctx
->cq_ring
;
433 tail
= ctx
->cached_cq_tail
;
435 * writes to the cq entry need to come after reading head; the
436 * control dependency is enough as we're using WRITE_ONCE to
439 if (tail
- READ_ONCE(ring
->r
.head
) == ring
->ring_entries
)
442 ctx
->cached_cq_tail
++;
443 return &ring
->cqes
[tail
& ctx
->cq_mask
];
446 static void io_cqring_fill_event(struct io_ring_ctx
*ctx
, u64 ki_user_data
,
447 long res
, unsigned ev_flags
)
449 struct io_uring_cqe
*cqe
;
452 * If we can't get a cq entry, userspace overflowed the
453 * submission (by quite a lot). Increment the overflow count in
456 cqe
= io_get_cqring(ctx
);
458 WRITE_ONCE(cqe
->user_data
, ki_user_data
);
459 WRITE_ONCE(cqe
->res
, res
);
460 WRITE_ONCE(cqe
->flags
, ev_flags
);
462 unsigned overflow
= READ_ONCE(ctx
->cq_ring
->overflow
);
464 WRITE_ONCE(ctx
->cq_ring
->overflow
, overflow
+ 1);
468 static void io_cqring_ev_posted(struct io_ring_ctx
*ctx
)
470 if (waitqueue_active(&ctx
->wait
))
472 if (waitqueue_active(&ctx
->sqo_wait
))
473 wake_up(&ctx
->sqo_wait
);
476 static void io_cqring_add_event(struct io_ring_ctx
*ctx
, u64 user_data
,
477 long res
, unsigned ev_flags
)
481 spin_lock_irqsave(&ctx
->completion_lock
, flags
);
482 io_cqring_fill_event(ctx
, user_data
, res
, ev_flags
);
483 io_commit_cqring(ctx
);
484 spin_unlock_irqrestore(&ctx
->completion_lock
, flags
);
486 io_cqring_ev_posted(ctx
);
489 static void io_ring_drop_ctx_refs(struct io_ring_ctx
*ctx
, unsigned refs
)
491 percpu_ref_put_many(&ctx
->refs
, refs
);
493 if (waitqueue_active(&ctx
->wait
))
497 static struct io_kiocb
*io_get_req(struct io_ring_ctx
*ctx
,
498 struct io_submit_state
*state
)
500 gfp_t gfp
= GFP_KERNEL
| __GFP_NOWARN
;
501 struct io_kiocb
*req
;
503 if (!percpu_ref_tryget(&ctx
->refs
))
507 req
= kmem_cache_alloc(req_cachep
, gfp
);
510 } else if (!state
->free_reqs
) {
514 sz
= min_t(size_t, state
->ios_left
, ARRAY_SIZE(state
->reqs
));
515 ret
= kmem_cache_alloc_bulk(req_cachep
, gfp
, sz
, state
->reqs
);
518 * Bulk alloc is all-or-nothing. If we fail to get a batch,
519 * retry single alloc to be on the safe side.
521 if (unlikely(ret
<= 0)) {
522 state
->reqs
[0] = kmem_cache_alloc(req_cachep
, gfp
);
527 state
->free_reqs
= ret
- 1;
529 req
= state
->reqs
[0];
531 req
= state
->reqs
[state
->cur_req
];
538 /* one is dropped after submission, the other at completion */
539 refcount_set(&req
->refs
, 2);
542 io_ring_drop_ctx_refs(ctx
, 1);
546 static void io_free_req_many(struct io_ring_ctx
*ctx
, void **reqs
, int *nr
)
549 kmem_cache_free_bulk(req_cachep
, *nr
, reqs
);
550 io_ring_drop_ctx_refs(ctx
, *nr
);
555 static void io_free_req(struct io_kiocb
*req
)
557 if (req
->file
&& !(req
->flags
& REQ_F_FIXED_FILE
))
559 io_ring_drop_ctx_refs(req
->ctx
, 1);
560 kmem_cache_free(req_cachep
, req
);
563 static void io_put_req(struct io_kiocb
*req
)
565 if (refcount_dec_and_test(&req
->refs
))
570 * Find and free completed poll iocbs
572 static void io_iopoll_complete(struct io_ring_ctx
*ctx
, unsigned int *nr_events
,
573 struct list_head
*done
)
575 void *reqs
[IO_IOPOLL_BATCH
];
576 struct io_kiocb
*req
;
580 while (!list_empty(done
)) {
581 req
= list_first_entry(done
, struct io_kiocb
, list
);
582 list_del(&req
->list
);
584 io_cqring_fill_event(ctx
, req
->user_data
, req
->error
, 0);
587 if (refcount_dec_and_test(&req
->refs
)) {
588 /* If we're not using fixed files, we have to pair the
589 * completion part with the file put. Use regular
590 * completions for those, only batch free for fixed
593 if (req
->flags
& REQ_F_FIXED_FILE
) {
594 reqs
[to_free
++] = req
;
595 if (to_free
== ARRAY_SIZE(reqs
))
596 io_free_req_many(ctx
, reqs
, &to_free
);
603 io_commit_cqring(ctx
);
604 io_free_req_many(ctx
, reqs
, &to_free
);
607 static int io_do_iopoll(struct io_ring_ctx
*ctx
, unsigned int *nr_events
,
610 struct io_kiocb
*req
, *tmp
;
616 * Only spin for completions if we don't have multiple devices hanging
617 * off our complete list, and we're under the requested amount.
619 spin
= !ctx
->poll_multi_file
&& *nr_events
< min
;
622 list_for_each_entry_safe(req
, tmp
, &ctx
->poll_list
, list
) {
623 struct kiocb
*kiocb
= &req
->rw
;
626 * Move completed entries to our local list. If we find a
627 * request that requires polling, break out and complete
628 * the done list first, if we have entries there.
630 if (req
->flags
& REQ_F_IOPOLL_COMPLETED
) {
631 list_move_tail(&req
->list
, &done
);
634 if (!list_empty(&done
))
637 ret
= kiocb
->ki_filp
->f_op
->iopoll(kiocb
, spin
);
646 if (!list_empty(&done
))
647 io_iopoll_complete(ctx
, nr_events
, &done
);
653 * Poll for a mininum of 'min' events. Note that if min == 0 we consider that a
654 * non-spinning poll check - we'll still enter the driver poll loop, but only
655 * as a non-spinning completion check.
657 static int io_iopoll_getevents(struct io_ring_ctx
*ctx
, unsigned int *nr_events
,
660 while (!list_empty(&ctx
->poll_list
)) {
663 ret
= io_do_iopoll(ctx
, nr_events
, min
);
666 if (!min
|| *nr_events
>= min
)
674 * We can't just wait for polled events to come to us, we have to actively
675 * find and complete them.
677 static void io_iopoll_reap_events(struct io_ring_ctx
*ctx
)
679 if (!(ctx
->flags
& IORING_SETUP_IOPOLL
))
682 mutex_lock(&ctx
->uring_lock
);
683 while (!list_empty(&ctx
->poll_list
)) {
684 unsigned int nr_events
= 0;
686 io_iopoll_getevents(ctx
, &nr_events
, 1);
688 mutex_unlock(&ctx
->uring_lock
);
691 static int io_iopoll_check(struct io_ring_ctx
*ctx
, unsigned *nr_events
,
699 if (*nr_events
< min
)
700 tmin
= min
- *nr_events
;
702 ret
= io_iopoll_getevents(ctx
, nr_events
, tmin
);
706 } while (min
&& !*nr_events
&& !need_resched());
711 static void kiocb_end_write(struct kiocb
*kiocb
)
713 if (kiocb
->ki_flags
& IOCB_WRITE
) {
714 struct inode
*inode
= file_inode(kiocb
->ki_filp
);
717 * Tell lockdep we inherited freeze protection from submission
720 if (S_ISREG(inode
->i_mode
))
721 __sb_writers_acquired(inode
->i_sb
, SB_FREEZE_WRITE
);
722 file_end_write(kiocb
->ki_filp
);
726 static void io_complete_rw(struct kiocb
*kiocb
, long res
, long res2
)
728 struct io_kiocb
*req
= container_of(kiocb
, struct io_kiocb
, rw
);
730 kiocb_end_write(kiocb
);
732 io_cqring_add_event(req
->ctx
, req
->user_data
, res
, 0);
736 static void io_complete_rw_iopoll(struct kiocb
*kiocb
, long res
, long res2
)
738 struct io_kiocb
*req
= container_of(kiocb
, struct io_kiocb
, rw
);
740 kiocb_end_write(kiocb
);
744 req
->flags
|= REQ_F_IOPOLL_COMPLETED
;
748 * After the iocb has been issued, it's safe to be found on the poll list.
749 * Adding the kiocb to the list AFTER submission ensures that we don't
750 * find it from a io_iopoll_getevents() thread before the issuer is done
751 * accessing the kiocb cookie.
753 static void io_iopoll_req_issued(struct io_kiocb
*req
)
755 struct io_ring_ctx
*ctx
= req
->ctx
;
758 * Track whether we have multiple files in our lists. This will impact
759 * how we do polling eventually, not spinning if we're on potentially
762 if (list_empty(&ctx
->poll_list
)) {
763 ctx
->poll_multi_file
= false;
764 } else if (!ctx
->poll_multi_file
) {
765 struct io_kiocb
*list_req
;
767 list_req
= list_first_entry(&ctx
->poll_list
, struct io_kiocb
,
769 if (list_req
->rw
.ki_filp
!= req
->rw
.ki_filp
)
770 ctx
->poll_multi_file
= true;
774 * For fast devices, IO may have already completed. If it has, add
775 * it to the front so we find it first.
777 if (req
->flags
& REQ_F_IOPOLL_COMPLETED
)
778 list_add(&req
->list
, &ctx
->poll_list
);
780 list_add_tail(&req
->list
, &ctx
->poll_list
);
783 static void io_file_put(struct io_submit_state
*state
)
786 int diff
= state
->has_refs
- state
->used_refs
;
789 fput_many(state
->file
, diff
);
795 * Get as many references to a file as we have IOs left in this submission,
796 * assuming most submissions are for one file, or at least that each file
797 * has more than one submission.
799 static struct file
*io_file_get(struct io_submit_state
*state
, int fd
)
805 if (state
->fd
== fd
) {
812 state
->file
= fget_many(fd
, state
->ios_left
);
817 state
->has_refs
= state
->ios_left
;
818 state
->used_refs
= 1;
824 * If we tracked the file through the SCM inflight mechanism, we could support
825 * any file. For now, just ensure that anything potentially problematic is done
828 static bool io_file_supports_async(struct file
*file
)
830 umode_t mode
= file_inode(file
)->i_mode
;
832 if (S_ISBLK(mode
) || S_ISCHR(mode
))
834 if (S_ISREG(mode
) && file
->f_op
!= &io_uring_fops
)
840 static int io_prep_rw(struct io_kiocb
*req
, const struct sqe_submit
*s
,
843 const struct io_uring_sqe
*sqe
= s
->sqe
;
844 struct io_ring_ctx
*ctx
= req
->ctx
;
845 struct kiocb
*kiocb
= &req
->rw
;
851 /* For -EAGAIN retry, everything is already prepped */
852 if (req
->flags
& REQ_F_PREPPED
)
855 if (force_nonblock
&& !io_file_supports_async(req
->file
))
856 force_nonblock
= false;
858 kiocb
->ki_pos
= READ_ONCE(sqe
->off
);
859 kiocb
->ki_flags
= iocb_flags(kiocb
->ki_filp
);
860 kiocb
->ki_hint
= ki_hint_validate(file_write_hint(kiocb
->ki_filp
));
862 ioprio
= READ_ONCE(sqe
->ioprio
);
864 ret
= ioprio_check_cap(ioprio
);
868 kiocb
->ki_ioprio
= ioprio
;
870 kiocb
->ki_ioprio
= get_current_ioprio();
872 ret
= kiocb_set_rw_flags(kiocb
, READ_ONCE(sqe
->rw_flags
));
876 /* don't allow async punt if RWF_NOWAIT was requested */
877 if (kiocb
->ki_flags
& IOCB_NOWAIT
)
878 req
->flags
|= REQ_F_NOWAIT
;
881 kiocb
->ki_flags
|= IOCB_NOWAIT
;
883 if (ctx
->flags
& IORING_SETUP_IOPOLL
) {
884 if (!(kiocb
->ki_flags
& IOCB_DIRECT
) ||
885 !kiocb
->ki_filp
->f_op
->iopoll
)
889 kiocb
->ki_flags
|= IOCB_HIPRI
;
890 kiocb
->ki_complete
= io_complete_rw_iopoll
;
892 if (kiocb
->ki_flags
& IOCB_HIPRI
)
894 kiocb
->ki_complete
= io_complete_rw
;
896 req
->flags
|= REQ_F_PREPPED
;
900 static inline void io_rw_done(struct kiocb
*kiocb
, ssize_t ret
)
906 case -ERESTARTNOINTR
:
907 case -ERESTARTNOHAND
:
908 case -ERESTART_RESTARTBLOCK
:
910 * We can't just restart the syscall, since previously
911 * submitted sqes may already be in progress. Just fail this
917 kiocb
->ki_complete(kiocb
, ret
, 0);
921 static int io_import_fixed(struct io_ring_ctx
*ctx
, int rw
,
922 const struct io_uring_sqe
*sqe
,
923 struct iov_iter
*iter
)
925 size_t len
= READ_ONCE(sqe
->len
);
926 struct io_mapped_ubuf
*imu
;
927 unsigned index
, buf_index
;
931 /* attempt to use fixed buffers without having provided iovecs */
932 if (unlikely(!ctx
->user_bufs
))
935 buf_index
= READ_ONCE(sqe
->buf_index
);
936 if (unlikely(buf_index
>= ctx
->nr_user_bufs
))
939 index
= array_index_nospec(buf_index
, ctx
->nr_user_bufs
);
940 imu
= &ctx
->user_bufs
[index
];
941 buf_addr
= READ_ONCE(sqe
->addr
);
944 if (buf_addr
+ len
< buf_addr
)
946 /* not inside the mapped region */
947 if (buf_addr
< imu
->ubuf
|| buf_addr
+ len
> imu
->ubuf
+ imu
->len
)
951 * May not be a start of buffer, set size appropriately
952 * and advance us to the beginning.
954 offset
= buf_addr
- imu
->ubuf
;
955 iov_iter_bvec(iter
, rw
, imu
->bvec
, imu
->nr_bvecs
, offset
+ len
);
957 iov_iter_advance(iter
, offset
);
959 /* don't drop a reference to these pages */
960 iter
->type
|= ITER_BVEC_FLAG_NO_REF
;
964 static int io_import_iovec(struct io_ring_ctx
*ctx
, int rw
,
965 const struct sqe_submit
*s
, struct iovec
**iovec
,
966 struct iov_iter
*iter
)
968 const struct io_uring_sqe
*sqe
= s
->sqe
;
969 void __user
*buf
= u64_to_user_ptr(READ_ONCE(sqe
->addr
));
970 size_t sqe_len
= READ_ONCE(sqe
->len
);
974 * We're reading ->opcode for the second time, but the first read
975 * doesn't care whether it's _FIXED or not, so it doesn't matter
976 * whether ->opcode changes concurrently. The first read does care
977 * about whether it is a READ or a WRITE, so we don't trust this read
978 * for that purpose and instead let the caller pass in the read/write
981 opcode
= READ_ONCE(sqe
->opcode
);
982 if (opcode
== IORING_OP_READ_FIXED
||
983 opcode
== IORING_OP_WRITE_FIXED
) {
984 int ret
= io_import_fixed(ctx
, rw
, sqe
, iter
);
994 return compat_import_iovec(rw
, buf
, sqe_len
, UIO_FASTIOV
,
998 return import_iovec(rw
, buf
, sqe_len
, UIO_FASTIOV
, iovec
, iter
);
1002 * Make a note of the last file/offset/direction we punted to async
1003 * context. We'll use this information to see if we can piggy back a
1004 * sequential request onto the previous one, if it's still hasn't been
1005 * completed by the async worker.
1007 static void io_async_list_note(int rw
, struct io_kiocb
*req
, size_t len
)
1009 struct async_list
*async_list
= &req
->ctx
->pending_async
[rw
];
1010 struct kiocb
*kiocb
= &req
->rw
;
1011 struct file
*filp
= kiocb
->ki_filp
;
1012 off_t io_end
= kiocb
->ki_pos
+ len
;
1014 if (filp
== async_list
->file
&& kiocb
->ki_pos
== async_list
->io_end
) {
1015 unsigned long max_pages
;
1017 /* Use 8x RA size as a decent limiter for both reads/writes */
1018 max_pages
= filp
->f_ra
.ra_pages
;
1020 max_pages
= VM_READAHEAD_PAGES
;
1023 /* If max pages are exceeded, reset the state */
1025 if (async_list
->io_pages
+ len
<= max_pages
) {
1026 req
->flags
|= REQ_F_SEQ_PREV
;
1027 async_list
->io_pages
+= len
;
1030 async_list
->io_pages
= 0;
1034 /* New file? Reset state. */
1035 if (async_list
->file
!= filp
) {
1036 async_list
->io_pages
= 0;
1037 async_list
->file
= filp
;
1039 async_list
->io_end
= io_end
;
1042 static int io_read(struct io_kiocb
*req
, const struct sqe_submit
*s
,
1043 bool force_nonblock
)
1045 struct iovec inline_vecs
[UIO_FASTIOV
], *iovec
= inline_vecs
;
1046 struct kiocb
*kiocb
= &req
->rw
;
1047 struct iov_iter iter
;
1052 ret
= io_prep_rw(req
, s
, force_nonblock
);
1055 file
= kiocb
->ki_filp
;
1057 if (unlikely(!(file
->f_mode
& FMODE_READ
)))
1059 if (unlikely(!file
->f_op
->read_iter
))
1062 ret
= io_import_iovec(req
->ctx
, READ
, s
, &iovec
, &iter
);
1066 iov_count
= iov_iter_count(&iter
);
1067 ret
= rw_verify_area(READ
, file
, &kiocb
->ki_pos
, iov_count
);
1071 /* Catch -EAGAIN return for forced non-blocking submission */
1072 ret2
= call_read_iter(file
, kiocb
, &iter
);
1073 if (!force_nonblock
|| ret2
!= -EAGAIN
) {
1074 io_rw_done(kiocb
, ret2
);
1077 * If ->needs_lock is true, we're already in async
1081 io_async_list_note(READ
, req
, iov_count
);
1089 static int io_write(struct io_kiocb
*req
, const struct sqe_submit
*s
,
1090 bool force_nonblock
)
1092 struct iovec inline_vecs
[UIO_FASTIOV
], *iovec
= inline_vecs
;
1093 struct kiocb
*kiocb
= &req
->rw
;
1094 struct iov_iter iter
;
1099 ret
= io_prep_rw(req
, s
, force_nonblock
);
1103 file
= kiocb
->ki_filp
;
1104 if (unlikely(!(file
->f_mode
& FMODE_WRITE
)))
1106 if (unlikely(!file
->f_op
->write_iter
))
1109 ret
= io_import_iovec(req
->ctx
, WRITE
, s
, &iovec
, &iter
);
1113 iov_count
= iov_iter_count(&iter
);
1116 if (force_nonblock
&& !(kiocb
->ki_flags
& IOCB_DIRECT
)) {
1117 /* If ->needs_lock is true, we're already in async context. */
1119 io_async_list_note(WRITE
, req
, iov_count
);
1123 ret
= rw_verify_area(WRITE
, file
, &kiocb
->ki_pos
, iov_count
);
1128 * Open-code file_start_write here to grab freeze protection,
1129 * which will be released by another thread in
1130 * io_complete_rw(). Fool lockdep by telling it the lock got
1131 * released so that it doesn't complain about the held lock when
1132 * we return to userspace.
1134 if (S_ISREG(file_inode(file
)->i_mode
)) {
1135 __sb_start_write(file_inode(file
)->i_sb
,
1136 SB_FREEZE_WRITE
, true);
1137 __sb_writers_release(file_inode(file
)->i_sb
,
1140 kiocb
->ki_flags
|= IOCB_WRITE
;
1142 ret2
= call_write_iter(file
, kiocb
, &iter
);
1143 if (!force_nonblock
|| ret2
!= -EAGAIN
) {
1144 io_rw_done(kiocb
, ret2
);
1147 * If ->needs_lock is true, we're already in async
1151 io_async_list_note(WRITE
, req
, iov_count
);
1161 * IORING_OP_NOP just posts a completion event, nothing else.
1163 static int io_nop(struct io_kiocb
*req
, u64 user_data
)
1165 struct io_ring_ctx
*ctx
= req
->ctx
;
1168 if (unlikely(ctx
->flags
& IORING_SETUP_IOPOLL
))
1171 io_cqring_add_event(ctx
, user_data
, err
, 0);
1176 static int io_prep_fsync(struct io_kiocb
*req
, const struct io_uring_sqe
*sqe
)
1178 struct io_ring_ctx
*ctx
= req
->ctx
;
1182 /* Prep already done (EAGAIN retry) */
1183 if (req
->flags
& REQ_F_PREPPED
)
1186 if (unlikely(ctx
->flags
& IORING_SETUP_IOPOLL
))
1188 if (unlikely(sqe
->addr
|| sqe
->ioprio
|| sqe
->buf_index
))
1191 req
->flags
|= REQ_F_PREPPED
;
1195 static int io_fsync(struct io_kiocb
*req
, const struct io_uring_sqe
*sqe
,
1196 bool force_nonblock
)
1198 loff_t sqe_off
= READ_ONCE(sqe
->off
);
1199 loff_t sqe_len
= READ_ONCE(sqe
->len
);
1200 loff_t end
= sqe_off
+ sqe_len
;
1201 unsigned fsync_flags
;
1204 fsync_flags
= READ_ONCE(sqe
->fsync_flags
);
1205 if (unlikely(fsync_flags
& ~IORING_FSYNC_DATASYNC
))
1208 ret
= io_prep_fsync(req
, sqe
);
1212 /* fsync always requires a blocking context */
1216 ret
= vfs_fsync_range(req
->rw
.ki_filp
, sqe_off
,
1217 end
> 0 ? end
: LLONG_MAX
,
1218 fsync_flags
& IORING_FSYNC_DATASYNC
);
1220 io_cqring_add_event(req
->ctx
, sqe
->user_data
, ret
, 0);
1225 static void io_poll_remove_one(struct io_kiocb
*req
)
1227 struct io_poll_iocb
*poll
= &req
->poll
;
1229 spin_lock(&poll
->head
->lock
);
1230 WRITE_ONCE(poll
->canceled
, true);
1231 if (!list_empty(&poll
->wait
.entry
)) {
1232 list_del_init(&poll
->wait
.entry
);
1233 queue_work(req
->ctx
->sqo_wq
, &req
->work
);
1235 spin_unlock(&poll
->head
->lock
);
1237 list_del_init(&req
->list
);
1240 static void io_poll_remove_all(struct io_ring_ctx
*ctx
)
1242 struct io_kiocb
*req
;
1244 spin_lock_irq(&ctx
->completion_lock
);
1245 while (!list_empty(&ctx
->cancel_list
)) {
1246 req
= list_first_entry(&ctx
->cancel_list
, struct io_kiocb
,list
);
1247 io_poll_remove_one(req
);
1249 spin_unlock_irq(&ctx
->completion_lock
);
1253 * Find a running poll command that matches one specified in sqe->addr,
1254 * and remove it if found.
1256 static int io_poll_remove(struct io_kiocb
*req
, const struct io_uring_sqe
*sqe
)
1258 struct io_ring_ctx
*ctx
= req
->ctx
;
1259 struct io_kiocb
*poll_req
, *next
;
1262 if (unlikely(req
->ctx
->flags
& IORING_SETUP_IOPOLL
))
1264 if (sqe
->ioprio
|| sqe
->off
|| sqe
->len
|| sqe
->buf_index
||
1268 spin_lock_irq(&ctx
->completion_lock
);
1269 list_for_each_entry_safe(poll_req
, next
, &ctx
->cancel_list
, list
) {
1270 if (READ_ONCE(sqe
->addr
) == poll_req
->user_data
) {
1271 io_poll_remove_one(poll_req
);
1276 spin_unlock_irq(&ctx
->completion_lock
);
1278 io_cqring_add_event(req
->ctx
, sqe
->user_data
, ret
, 0);
1283 static void io_poll_complete(struct io_ring_ctx
*ctx
, struct io_kiocb
*req
,
1286 req
->poll
.done
= true;
1287 io_cqring_fill_event(ctx
, req
->user_data
, mangle_poll(mask
), 0);
1288 io_commit_cqring(ctx
);
1291 static void io_poll_complete_work(struct work_struct
*work
)
1293 struct io_kiocb
*req
= container_of(work
, struct io_kiocb
, work
);
1294 struct io_poll_iocb
*poll
= &req
->poll
;
1295 struct poll_table_struct pt
= { ._key
= poll
->events
};
1296 struct io_ring_ctx
*ctx
= req
->ctx
;
1299 if (!READ_ONCE(poll
->canceled
))
1300 mask
= vfs_poll(poll
->file
, &pt
) & poll
->events
;
1303 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1304 * calling ->ki_cancel. We need the ctx_lock roundtrip here to
1305 * synchronize with them. In the cancellation case the list_del_init
1306 * itself is not actually needed, but harmless so we keep it in to
1307 * avoid further branches in the fast path.
1309 spin_lock_irq(&ctx
->completion_lock
);
1310 if (!mask
&& !READ_ONCE(poll
->canceled
)) {
1311 add_wait_queue(poll
->head
, &poll
->wait
);
1312 spin_unlock_irq(&ctx
->completion_lock
);
1315 list_del_init(&req
->list
);
1316 io_poll_complete(ctx
, req
, mask
);
1317 spin_unlock_irq(&ctx
->completion_lock
);
1319 io_cqring_ev_posted(ctx
);
1323 static int io_poll_wake(struct wait_queue_entry
*wait
, unsigned mode
, int sync
,
1326 struct io_poll_iocb
*poll
= container_of(wait
, struct io_poll_iocb
,
1328 struct io_kiocb
*req
= container_of(poll
, struct io_kiocb
, poll
);
1329 struct io_ring_ctx
*ctx
= req
->ctx
;
1330 __poll_t mask
= key_to_poll(key
);
1331 unsigned long flags
;
1333 /* for instances that support it check for an event match first: */
1334 if (mask
&& !(mask
& poll
->events
))
1337 list_del_init(&poll
->wait
.entry
);
1339 if (mask
&& spin_trylock_irqsave(&ctx
->completion_lock
, flags
)) {
1340 list_del(&req
->list
);
1341 io_poll_complete(ctx
, req
, mask
);
1342 spin_unlock_irqrestore(&ctx
->completion_lock
, flags
);
1344 io_cqring_ev_posted(ctx
);
1347 queue_work(ctx
->sqo_wq
, &req
->work
);
1353 struct io_poll_table
{
1354 struct poll_table_struct pt
;
1355 struct io_kiocb
*req
;
1359 static void io_poll_queue_proc(struct file
*file
, struct wait_queue_head
*head
,
1360 struct poll_table_struct
*p
)
1362 struct io_poll_table
*pt
= container_of(p
, struct io_poll_table
, pt
);
1364 if (unlikely(pt
->req
->poll
.head
)) {
1365 pt
->error
= -EINVAL
;
1370 pt
->req
->poll
.head
= head
;
1371 add_wait_queue(head
, &pt
->req
->poll
.wait
);
1374 static int io_poll_add(struct io_kiocb
*req
, const struct io_uring_sqe
*sqe
)
1376 struct io_poll_iocb
*poll
= &req
->poll
;
1377 struct io_ring_ctx
*ctx
= req
->ctx
;
1378 struct io_poll_table ipt
;
1379 bool cancel
= false;
1383 if (unlikely(req
->ctx
->flags
& IORING_SETUP_IOPOLL
))
1385 if (sqe
->addr
|| sqe
->ioprio
|| sqe
->off
|| sqe
->len
|| sqe
->buf_index
)
1390 INIT_WORK(&req
->work
, io_poll_complete_work
);
1391 events
= READ_ONCE(sqe
->poll_events
);
1392 poll
->events
= demangle_poll(events
) | EPOLLERR
| EPOLLHUP
;
1396 poll
->canceled
= false;
1398 ipt
.pt
._qproc
= io_poll_queue_proc
;
1399 ipt
.pt
._key
= poll
->events
;
1401 ipt
.error
= -EINVAL
; /* same as no support for IOCB_CMD_POLL */
1403 /* initialized the list so that we can do list_empty checks */
1404 INIT_LIST_HEAD(&poll
->wait
.entry
);
1405 init_waitqueue_func_entry(&poll
->wait
, io_poll_wake
);
1407 mask
= vfs_poll(poll
->file
, &ipt
.pt
) & poll
->events
;
1409 spin_lock_irq(&ctx
->completion_lock
);
1410 if (likely(poll
->head
)) {
1411 spin_lock(&poll
->head
->lock
);
1412 if (unlikely(list_empty(&poll
->wait
.entry
))) {
1418 if (mask
|| ipt
.error
)
1419 list_del_init(&poll
->wait
.entry
);
1421 WRITE_ONCE(poll
->canceled
, true);
1422 else if (!poll
->done
) /* actually waiting for an event */
1423 list_add_tail(&req
->list
, &ctx
->cancel_list
);
1424 spin_unlock(&poll
->head
->lock
);
1426 if (mask
) { /* no async, we'd stolen it */
1427 req
->error
= mangle_poll(mask
);
1429 io_poll_complete(ctx
, req
, mask
);
1431 spin_unlock_irq(&ctx
->completion_lock
);
1434 io_cqring_ev_posted(ctx
);
1440 static int __io_submit_sqe(struct io_ring_ctx
*ctx
, struct io_kiocb
*req
,
1441 const struct sqe_submit
*s
, bool force_nonblock
)
1445 if (unlikely(s
->index
>= ctx
->sq_entries
))
1447 req
->user_data
= READ_ONCE(s
->sqe
->user_data
);
1449 opcode
= READ_ONCE(s
->sqe
->opcode
);
1452 ret
= io_nop(req
, req
->user_data
);
1454 case IORING_OP_READV
:
1455 if (unlikely(s
->sqe
->buf_index
))
1457 ret
= io_read(req
, s
, force_nonblock
);
1459 case IORING_OP_WRITEV
:
1460 if (unlikely(s
->sqe
->buf_index
))
1462 ret
= io_write(req
, s
, force_nonblock
);
1464 case IORING_OP_READ_FIXED
:
1465 ret
= io_read(req
, s
, force_nonblock
);
1467 case IORING_OP_WRITE_FIXED
:
1468 ret
= io_write(req
, s
, force_nonblock
);
1470 case IORING_OP_FSYNC
:
1471 ret
= io_fsync(req
, s
->sqe
, force_nonblock
);
1473 case IORING_OP_POLL_ADD
:
1474 ret
= io_poll_add(req
, s
->sqe
);
1476 case IORING_OP_POLL_REMOVE
:
1477 ret
= io_poll_remove(req
, s
->sqe
);
1487 if (ctx
->flags
& IORING_SETUP_IOPOLL
) {
1488 if (req
->error
== -EAGAIN
)
1491 /* workqueue context doesn't hold uring_lock, grab it now */
1493 mutex_lock(&ctx
->uring_lock
);
1494 io_iopoll_req_issued(req
);
1496 mutex_unlock(&ctx
->uring_lock
);
1502 static struct async_list
*io_async_list_from_sqe(struct io_ring_ctx
*ctx
,
1503 const struct io_uring_sqe
*sqe
)
1505 switch (sqe
->opcode
) {
1506 case IORING_OP_READV
:
1507 case IORING_OP_READ_FIXED
:
1508 return &ctx
->pending_async
[READ
];
1509 case IORING_OP_WRITEV
:
1510 case IORING_OP_WRITE_FIXED
:
1511 return &ctx
->pending_async
[WRITE
];
1517 static inline bool io_sqe_needs_user(const struct io_uring_sqe
*sqe
)
1519 u8 opcode
= READ_ONCE(sqe
->opcode
);
1521 return !(opcode
== IORING_OP_READ_FIXED
||
1522 opcode
== IORING_OP_WRITE_FIXED
);
1525 static void io_sq_wq_submit_work(struct work_struct
*work
)
1527 struct io_kiocb
*req
= container_of(work
, struct io_kiocb
, work
);
1528 struct io_ring_ctx
*ctx
= req
->ctx
;
1529 struct mm_struct
*cur_mm
= NULL
;
1530 struct async_list
*async_list
;
1531 LIST_HEAD(req_list
);
1532 mm_segment_t old_fs
;
1535 async_list
= io_async_list_from_sqe(ctx
, req
->submit
.sqe
);
1538 struct sqe_submit
*s
= &req
->submit
;
1539 const struct io_uring_sqe
*sqe
= s
->sqe
;
1541 /* Ensure we clear previously set non-block flag */
1542 req
->rw
.ki_flags
&= ~IOCB_NOWAIT
;
1545 if (io_sqe_needs_user(sqe
) && !cur_mm
) {
1546 if (!mmget_not_zero(ctx
->sqo_mm
)) {
1549 cur_mm
= ctx
->sqo_mm
;
1557 s
->has_user
= cur_mm
!= NULL
;
1558 s
->needs_lock
= true;
1560 ret
= __io_submit_sqe(ctx
, req
, s
, false);
1562 * We can get EAGAIN for polled IO even though
1563 * we're forcing a sync submission from here,
1564 * since we can't wait for request slots on the
1573 /* drop submission reference */
1577 io_cqring_add_event(ctx
, sqe
->user_data
, ret
, 0);
1581 /* async context always use a copy of the sqe */
1586 if (!list_empty(&req_list
)) {
1587 req
= list_first_entry(&req_list
, struct io_kiocb
,
1589 list_del(&req
->list
);
1592 if (list_empty(&async_list
->list
))
1596 spin_lock(&async_list
->lock
);
1597 if (list_empty(&async_list
->list
)) {
1598 spin_unlock(&async_list
->lock
);
1601 list_splice_init(&async_list
->list
, &req_list
);
1602 spin_unlock(&async_list
->lock
);
1604 req
= list_first_entry(&req_list
, struct io_kiocb
, list
);
1605 list_del(&req
->list
);
1609 * Rare case of racing with a submitter. If we find the count has
1610 * dropped to zero AND we have pending work items, then restart
1611 * the processing. This is a tiny race window.
1614 ret
= atomic_dec_return(&async_list
->cnt
);
1615 while (!ret
&& !list_empty(&async_list
->list
)) {
1616 spin_lock(&async_list
->lock
);
1617 atomic_inc(&async_list
->cnt
);
1618 list_splice_init(&async_list
->list
, &req_list
);
1619 spin_unlock(&async_list
->lock
);
1621 if (!list_empty(&req_list
)) {
1622 req
= list_first_entry(&req_list
,
1623 struct io_kiocb
, list
);
1624 list_del(&req
->list
);
1627 ret
= atomic_dec_return(&async_list
->cnt
);
1639 * See if we can piggy back onto previously submitted work, that is still
1640 * running. We currently only allow this if the new request is sequential
1641 * to the previous one we punted.
1643 static bool io_add_to_prev_work(struct async_list
*list
, struct io_kiocb
*req
)
1649 if (!(req
->flags
& REQ_F_SEQ_PREV
))
1651 if (!atomic_read(&list
->cnt
))
1655 spin_lock(&list
->lock
);
1656 list_add_tail(&req
->list
, &list
->list
);
1657 if (!atomic_read(&list
->cnt
)) {
1658 list_del_init(&req
->list
);
1661 spin_unlock(&list
->lock
);
1665 static bool io_op_needs_file(const struct io_uring_sqe
*sqe
)
1667 int op
= READ_ONCE(sqe
->opcode
);
1671 case IORING_OP_POLL_REMOVE
:
1678 static int io_req_set_file(struct io_ring_ctx
*ctx
, const struct sqe_submit
*s
,
1679 struct io_submit_state
*state
, struct io_kiocb
*req
)
1684 flags
= READ_ONCE(s
->sqe
->flags
);
1685 fd
= READ_ONCE(s
->sqe
->fd
);
1687 if (!io_op_needs_file(s
->sqe
)) {
1692 if (flags
& IOSQE_FIXED_FILE
) {
1693 if (unlikely(!ctx
->user_files
||
1694 (unsigned) fd
>= ctx
->nr_user_files
))
1696 req
->file
= ctx
->user_files
[fd
];
1697 req
->flags
|= REQ_F_FIXED_FILE
;
1699 if (s
->needs_fixed_file
)
1701 req
->file
= io_file_get(state
, fd
);
1702 if (unlikely(!req
->file
))
1709 static int io_submit_sqe(struct io_ring_ctx
*ctx
, struct sqe_submit
*s
,
1710 struct io_submit_state
*state
)
1712 struct io_kiocb
*req
;
1715 /* enforce forwards compatibility on users */
1716 if (unlikely(s
->sqe
->flags
& ~IOSQE_FIXED_FILE
))
1719 req
= io_get_req(ctx
, state
);
1723 ret
= io_req_set_file(ctx
, s
, state
, req
);
1727 ret
= __io_submit_sqe(ctx
, req
, s
, true);
1728 if (ret
== -EAGAIN
&& !(req
->flags
& REQ_F_NOWAIT
)) {
1729 struct io_uring_sqe
*sqe_copy
;
1731 sqe_copy
= kmalloc(sizeof(*sqe_copy
), GFP_KERNEL
);
1733 struct async_list
*list
;
1735 memcpy(sqe_copy
, s
->sqe
, sizeof(*sqe_copy
));
1738 memcpy(&req
->submit
, s
, sizeof(*s
));
1739 list
= io_async_list_from_sqe(ctx
, s
->sqe
);
1740 if (!io_add_to_prev_work(list
, req
)) {
1742 atomic_inc(&list
->cnt
);
1743 INIT_WORK(&req
->work
, io_sq_wq_submit_work
);
1744 queue_work(ctx
->sqo_wq
, &req
->work
);
1748 * Queued up for async execution, worker will release
1749 * submit reference when the iocb is actually
1757 /* drop submission reference */
1760 /* and drop final reference, if we failed */
1768 * Batched submission is done, ensure local IO is flushed out.
1770 static void io_submit_state_end(struct io_submit_state
*state
)
1772 blk_finish_plug(&state
->plug
);
1774 if (state
->free_reqs
)
1775 kmem_cache_free_bulk(req_cachep
, state
->free_reqs
,
1776 &state
->reqs
[state
->cur_req
]);
1780 * Start submission side cache.
1782 static void io_submit_state_start(struct io_submit_state
*state
,
1783 struct io_ring_ctx
*ctx
, unsigned max_ios
)
1785 blk_start_plug(&state
->plug
);
1786 state
->free_reqs
= 0;
1788 state
->ios_left
= max_ios
;
1791 static void io_commit_sqring(struct io_ring_ctx
*ctx
)
1793 struct io_sq_ring
*ring
= ctx
->sq_ring
;
1795 if (ctx
->cached_sq_head
!= READ_ONCE(ring
->r
.head
)) {
1797 * Ensure any loads from the SQEs are done at this point,
1798 * since once we write the new head, the application could
1799 * write new data to them.
1801 smp_store_release(&ring
->r
.head
, ctx
->cached_sq_head
);
1806 * Fetch an sqe, if one is available. Note that s->sqe will point to memory
1807 * that is mapped by userspace. This means that care needs to be taken to
1808 * ensure that reads are stable, as we cannot rely on userspace always
1809 * being a good citizen. If members of the sqe are validated and then later
1810 * used, it's important that those reads are done through READ_ONCE() to
1811 * prevent a re-load down the line.
1813 static bool io_get_sqring(struct io_ring_ctx
*ctx
, struct sqe_submit
*s
)
1815 struct io_sq_ring
*ring
= ctx
->sq_ring
;
1819 * The cached sq head (or cq tail) serves two purposes:
1821 * 1) allows us to batch the cost of updating the user visible
1823 * 2) allows the kernel side to track the head on its own, even
1824 * though the application is the one updating it.
1826 head
= ctx
->cached_sq_head
;
1827 /* make sure SQ entry isn't read before tail */
1828 if (head
== smp_load_acquire(&ring
->r
.tail
))
1831 head
= READ_ONCE(ring
->array
[head
& ctx
->sq_mask
]);
1832 if (head
< ctx
->sq_entries
) {
1834 s
->sqe
= &ctx
->sq_sqes
[head
];
1835 ctx
->cached_sq_head
++;
1839 /* drop invalid entries */
1840 ctx
->cached_sq_head
++;
1845 static int io_submit_sqes(struct io_ring_ctx
*ctx
, struct sqe_submit
*sqes
,
1846 unsigned int nr
, bool has_user
, bool mm_fault
)
1848 struct io_submit_state state
, *statep
= NULL
;
1849 int ret
, i
, submitted
= 0;
1851 if (nr
> IO_PLUG_THRESHOLD
) {
1852 io_submit_state_start(&state
, ctx
, nr
);
1856 for (i
= 0; i
< nr
; i
++) {
1857 if (unlikely(mm_fault
)) {
1860 sqes
[i
].has_user
= has_user
;
1861 sqes
[i
].needs_lock
= true;
1862 sqes
[i
].needs_fixed_file
= true;
1863 ret
= io_submit_sqe(ctx
, &sqes
[i
], statep
);
1870 io_cqring_add_event(ctx
, sqes
[i
].sqe
->user_data
, ret
, 0);
1874 io_submit_state_end(&state
);
1879 static int io_sq_thread(void *data
)
1881 struct sqe_submit sqes
[IO_IOPOLL_BATCH
];
1882 struct io_ring_ctx
*ctx
= data
;
1883 struct mm_struct
*cur_mm
= NULL
;
1884 mm_segment_t old_fs
;
1887 unsigned long timeout
;
1892 timeout
= inflight
= 0;
1893 while (!kthread_should_stop() && !ctx
->sqo_stop
) {
1894 bool all_fixed
, mm_fault
= false;
1898 unsigned nr_events
= 0;
1900 if (ctx
->flags
& IORING_SETUP_IOPOLL
) {
1902 * We disallow the app entering submit/complete
1903 * with polling, but we still need to lock the
1904 * ring to prevent racing with polled issue
1905 * that got punted to a workqueue.
1907 mutex_lock(&ctx
->uring_lock
);
1908 io_iopoll_check(ctx
, &nr_events
, 0);
1909 mutex_unlock(&ctx
->uring_lock
);
1912 * Normal IO, just pretend everything completed.
1913 * We don't have to poll completions for that.
1915 nr_events
= inflight
;
1918 inflight
-= nr_events
;
1920 timeout
= jiffies
+ ctx
->sq_thread_idle
;
1923 if (!io_get_sqring(ctx
, &sqes
[0])) {
1925 * We're polling. If we're within the defined idle
1926 * period, then let us spin without work before going
1929 if (inflight
|| !time_after(jiffies
, timeout
)) {
1935 * Drop cur_mm before scheduling, we can't hold it for
1936 * long periods (or over schedule()). Do this before
1937 * adding ourselves to the waitqueue, as the unuse/drop
1946 prepare_to_wait(&ctx
->sqo_wait
, &wait
,
1947 TASK_INTERRUPTIBLE
);
1949 /* Tell userspace we may need a wakeup call */
1950 ctx
->sq_ring
->flags
|= IORING_SQ_NEED_WAKEUP
;
1951 /* make sure to read SQ tail after writing flags */
1954 if (!io_get_sqring(ctx
, &sqes
[0])) {
1955 if (kthread_should_stop()) {
1956 finish_wait(&ctx
->sqo_wait
, &wait
);
1959 if (signal_pending(current
))
1960 flush_signals(current
);
1962 finish_wait(&ctx
->sqo_wait
, &wait
);
1964 ctx
->sq_ring
->flags
&= ~IORING_SQ_NEED_WAKEUP
;
1967 finish_wait(&ctx
->sqo_wait
, &wait
);
1969 ctx
->sq_ring
->flags
&= ~IORING_SQ_NEED_WAKEUP
;
1975 if (all_fixed
&& io_sqe_needs_user(sqes
[i
].sqe
))
1979 if (i
== ARRAY_SIZE(sqes
))
1981 } while (io_get_sqring(ctx
, &sqes
[i
]));
1983 /* Unless all new commands are FIXED regions, grab mm */
1984 if (!all_fixed
&& !cur_mm
) {
1985 mm_fault
= !mmget_not_zero(ctx
->sqo_mm
);
1987 use_mm(ctx
->sqo_mm
);
1988 cur_mm
= ctx
->sqo_mm
;
1992 inflight
+= io_submit_sqes(ctx
, sqes
, i
, cur_mm
!= NULL
,
1995 /* Commit SQ ring head once we've consumed all SQEs */
1996 io_commit_sqring(ctx
);
2005 if (kthread_should_park())
2011 static int io_ring_submit(struct io_ring_ctx
*ctx
, unsigned int to_submit
)
2013 struct io_submit_state state
, *statep
= NULL
;
2016 if (to_submit
> IO_PLUG_THRESHOLD
) {
2017 io_submit_state_start(&state
, ctx
, to_submit
);
2021 for (i
= 0; i
< to_submit
; i
++) {
2022 struct sqe_submit s
;
2025 if (!io_get_sqring(ctx
, &s
))
2029 s
.needs_lock
= false;
2030 s
.needs_fixed_file
= false;
2033 ret
= io_submit_sqe(ctx
, &s
, statep
);
2035 io_cqring_add_event(ctx
, s
.sqe
->user_data
, ret
, 0);
2037 io_commit_sqring(ctx
);
2040 io_submit_state_end(statep
);
2045 static unsigned io_cqring_events(struct io_cq_ring
*ring
)
2047 return READ_ONCE(ring
->r
.tail
) - READ_ONCE(ring
->r
.head
);
2051 * Wait until events become available, if we don't already have some. The
2052 * application must reap them itself, as they reside on the shared cq ring.
2054 static int io_cqring_wait(struct io_ring_ctx
*ctx
, int min_events
,
2055 const sigset_t __user
*sig
, size_t sigsz
)
2057 struct io_cq_ring
*ring
= ctx
->cq_ring
;
2058 sigset_t ksigmask
, sigsaved
;
2062 /* See comment at the top of this file */
2064 if (io_cqring_events(ring
) >= min_events
)
2068 #ifdef CONFIG_COMPAT
2069 if (in_compat_syscall())
2070 ret
= set_compat_user_sigmask((const compat_sigset_t __user
*)sig
,
2071 &ksigmask
, &sigsaved
, sigsz
);
2074 ret
= set_user_sigmask(sig
, &ksigmask
,
2082 prepare_to_wait(&ctx
->wait
, &wait
, TASK_INTERRUPTIBLE
);
2085 /* See comment at the top of this file */
2087 if (io_cqring_events(ring
) >= min_events
)
2093 if (signal_pending(current
))
2097 finish_wait(&ctx
->wait
, &wait
);
2100 restore_user_sigmask(sig
, &sigsaved
);
2102 return READ_ONCE(ring
->r
.head
) == READ_ONCE(ring
->r
.tail
) ? ret
: 0;
2105 static void __io_sqe_files_unregister(struct io_ring_ctx
*ctx
)
2107 #if defined(CONFIG_UNIX)
2108 if (ctx
->ring_sock
) {
2109 struct sock
*sock
= ctx
->ring_sock
->sk
;
2110 struct sk_buff
*skb
;
2112 while ((skb
= skb_dequeue(&sock
->sk_receive_queue
)) != NULL
)
2118 for (i
= 0; i
< ctx
->nr_user_files
; i
++)
2119 fput(ctx
->user_files
[i
]);
2123 static int io_sqe_files_unregister(struct io_ring_ctx
*ctx
)
2125 if (!ctx
->user_files
)
2128 __io_sqe_files_unregister(ctx
);
2129 kfree(ctx
->user_files
);
2130 ctx
->user_files
= NULL
;
2131 ctx
->nr_user_files
= 0;
2135 static void io_sq_thread_stop(struct io_ring_ctx
*ctx
)
2137 if (ctx
->sqo_thread
) {
2140 kthread_park(ctx
->sqo_thread
);
2141 kthread_stop(ctx
->sqo_thread
);
2142 ctx
->sqo_thread
= NULL
;
2146 static void io_finish_async(struct io_ring_ctx
*ctx
)
2148 io_sq_thread_stop(ctx
);
2151 destroy_workqueue(ctx
->sqo_wq
);
2156 #if defined(CONFIG_UNIX)
2157 static void io_destruct_skb(struct sk_buff
*skb
)
2159 struct io_ring_ctx
*ctx
= skb
->sk
->sk_user_data
;
2161 io_finish_async(ctx
);
2162 unix_destruct_scm(skb
);
2166 * Ensure the UNIX gc is aware of our file set, so we are certain that
2167 * the io_uring can be safely unregistered on process exit, even if we have
2168 * loops in the file referencing.
2170 static int __io_sqe_files_scm(struct io_ring_ctx
*ctx
, int nr
, int offset
)
2172 struct sock
*sk
= ctx
->ring_sock
->sk
;
2173 struct scm_fp_list
*fpl
;
2174 struct sk_buff
*skb
;
2177 if (!capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
)) {
2178 unsigned long inflight
= ctx
->user
->unix_inflight
+ nr
;
2180 if (inflight
> task_rlimit(current
, RLIMIT_NOFILE
))
2184 fpl
= kzalloc(sizeof(*fpl
), GFP_KERNEL
);
2188 skb
= alloc_skb(0, GFP_KERNEL
);
2195 skb
->destructor
= io_destruct_skb
;
2197 fpl
->user
= get_uid(ctx
->user
);
2198 for (i
= 0; i
< nr
; i
++) {
2199 fpl
->fp
[i
] = get_file(ctx
->user_files
[i
+ offset
]);
2200 unix_inflight(fpl
->user
, fpl
->fp
[i
]);
2203 fpl
->max
= fpl
->count
= nr
;
2204 UNIXCB(skb
).fp
= fpl
;
2205 refcount_add(skb
->truesize
, &sk
->sk_wmem_alloc
);
2206 skb_queue_head(&sk
->sk_receive_queue
, skb
);
2208 for (i
= 0; i
< nr
; i
++)
2215 * If UNIX sockets are enabled, fd passing can cause a reference cycle which
2216 * causes regular reference counting to break down. We rely on the UNIX
2217 * garbage collection to take care of this problem for us.
2219 static int io_sqe_files_scm(struct io_ring_ctx
*ctx
)
2221 unsigned left
, total
;
2225 left
= ctx
->nr_user_files
;
2227 unsigned this_files
= min_t(unsigned, left
, SCM_MAX_FD
);
2230 ret
= __io_sqe_files_scm(ctx
, this_files
, total
);
2234 total
+= this_files
;
2240 while (total
< ctx
->nr_user_files
) {
2241 fput(ctx
->user_files
[total
]);
2248 static int io_sqe_files_scm(struct io_ring_ctx
*ctx
)
2254 static int io_sqe_files_register(struct io_ring_ctx
*ctx
, void __user
*arg
,
2257 __s32 __user
*fds
= (__s32 __user
*) arg
;
2261 if (ctx
->user_files
)
2265 if (nr_args
> IORING_MAX_FIXED_FILES
)
2268 ctx
->user_files
= kcalloc(nr_args
, sizeof(struct file
*), GFP_KERNEL
);
2269 if (!ctx
->user_files
)
2272 for (i
= 0; i
< nr_args
; i
++) {
2274 if (copy_from_user(&fd
, &fds
[i
], sizeof(fd
)))
2277 ctx
->user_files
[i
] = fget(fd
);
2280 if (!ctx
->user_files
[i
])
2283 * Don't allow io_uring instances to be registered. If UNIX
2284 * isn't enabled, then this causes a reference cycle and this
2285 * instance can never get freed. If UNIX is enabled we'll
2286 * handle it just fine, but there's still no point in allowing
2287 * a ring fd as it doesn't support regular read/write anyway.
2289 if (ctx
->user_files
[i
]->f_op
== &io_uring_fops
) {
2290 fput(ctx
->user_files
[i
]);
2293 ctx
->nr_user_files
++;
2298 for (i
= 0; i
< ctx
->nr_user_files
; i
++)
2299 fput(ctx
->user_files
[i
]);
2301 kfree(ctx
->user_files
);
2302 ctx
->user_files
= NULL
;
2303 ctx
->nr_user_files
= 0;
2307 ret
= io_sqe_files_scm(ctx
);
2309 io_sqe_files_unregister(ctx
);
2314 static int io_sq_offload_start(struct io_ring_ctx
*ctx
,
2315 struct io_uring_params
*p
)
2319 init_waitqueue_head(&ctx
->sqo_wait
);
2320 mmgrab(current
->mm
);
2321 ctx
->sqo_mm
= current
->mm
;
2323 if (ctx
->flags
& IORING_SETUP_SQPOLL
) {
2325 if (!capable(CAP_SYS_ADMIN
))
2328 ctx
->sq_thread_idle
= msecs_to_jiffies(p
->sq_thread_idle
);
2329 if (!ctx
->sq_thread_idle
)
2330 ctx
->sq_thread_idle
= HZ
;
2332 if (p
->flags
& IORING_SETUP_SQ_AFF
) {
2333 int cpu
= array_index_nospec(p
->sq_thread_cpu
,
2337 if (!cpu_possible(cpu
))
2340 ctx
->sqo_thread
= kthread_create_on_cpu(io_sq_thread
,
2344 ctx
->sqo_thread
= kthread_create(io_sq_thread
, ctx
,
2347 if (IS_ERR(ctx
->sqo_thread
)) {
2348 ret
= PTR_ERR(ctx
->sqo_thread
);
2349 ctx
->sqo_thread
= NULL
;
2352 wake_up_process(ctx
->sqo_thread
);
2353 } else if (p
->flags
& IORING_SETUP_SQ_AFF
) {
2354 /* Can't have SQ_AFF without SQPOLL */
2359 /* Do QD, or 2 * CPUS, whatever is smallest */
2360 ctx
->sqo_wq
= alloc_workqueue("io_ring-wq", WQ_UNBOUND
| WQ_FREEZABLE
,
2361 min(ctx
->sq_entries
- 1, 2 * num_online_cpus()));
2369 io_sq_thread_stop(ctx
);
2370 mmdrop(ctx
->sqo_mm
);
2375 static void io_unaccount_mem(struct user_struct
*user
, unsigned long nr_pages
)
2377 atomic_long_sub(nr_pages
, &user
->locked_vm
);
2380 static int io_account_mem(struct user_struct
*user
, unsigned long nr_pages
)
2382 unsigned long page_limit
, cur_pages
, new_pages
;
2384 /* Don't allow more pages than we can safely lock */
2385 page_limit
= rlimit(RLIMIT_MEMLOCK
) >> PAGE_SHIFT
;
2388 cur_pages
= atomic_long_read(&user
->locked_vm
);
2389 new_pages
= cur_pages
+ nr_pages
;
2390 if (new_pages
> page_limit
)
2392 } while (atomic_long_cmpxchg(&user
->locked_vm
, cur_pages
,
2393 new_pages
) != cur_pages
);
2398 static void io_mem_free(void *ptr
)
2405 page
= virt_to_head_page(ptr
);
2406 if (put_page_testzero(page
))
2407 free_compound_page(page
);
2410 static void *io_mem_alloc(size_t size
)
2412 gfp_t gfp_flags
= GFP_KERNEL
| __GFP_ZERO
| __GFP_NOWARN
| __GFP_COMP
|
2415 return (void *) __get_free_pages(gfp_flags
, get_order(size
));
2418 static unsigned long ring_pages(unsigned sq_entries
, unsigned cq_entries
)
2420 struct io_sq_ring
*sq_ring
;
2421 struct io_cq_ring
*cq_ring
;
2424 bytes
= struct_size(sq_ring
, array
, sq_entries
);
2425 bytes
+= array_size(sizeof(struct io_uring_sqe
), sq_entries
);
2426 bytes
+= struct_size(cq_ring
, cqes
, cq_entries
);
2428 return (bytes
+ PAGE_SIZE
- 1) / PAGE_SIZE
;
2431 static int io_sqe_buffer_unregister(struct io_ring_ctx
*ctx
)
2435 if (!ctx
->user_bufs
)
2438 for (i
= 0; i
< ctx
->nr_user_bufs
; i
++) {
2439 struct io_mapped_ubuf
*imu
= &ctx
->user_bufs
[i
];
2441 for (j
= 0; j
< imu
->nr_bvecs
; j
++)
2442 put_page(imu
->bvec
[j
].bv_page
);
2444 if (ctx
->account_mem
)
2445 io_unaccount_mem(ctx
->user
, imu
->nr_bvecs
);
2450 kfree(ctx
->user_bufs
);
2451 ctx
->user_bufs
= NULL
;
2452 ctx
->nr_user_bufs
= 0;
2456 static int io_copy_iov(struct io_ring_ctx
*ctx
, struct iovec
*dst
,
2457 void __user
*arg
, unsigned index
)
2459 struct iovec __user
*src
;
2461 #ifdef CONFIG_COMPAT
2463 struct compat_iovec __user
*ciovs
;
2464 struct compat_iovec ciov
;
2466 ciovs
= (struct compat_iovec __user
*) arg
;
2467 if (copy_from_user(&ciov
, &ciovs
[index
], sizeof(ciov
)))
2470 dst
->iov_base
= (void __user
*) (unsigned long) ciov
.iov_base
;
2471 dst
->iov_len
= ciov
.iov_len
;
2475 src
= (struct iovec __user
*) arg
;
2476 if (copy_from_user(dst
, &src
[index
], sizeof(*dst
)))
2481 static int io_sqe_buffer_register(struct io_ring_ctx
*ctx
, void __user
*arg
,
2484 struct vm_area_struct
**vmas
= NULL
;
2485 struct page
**pages
= NULL
;
2486 int i
, j
, got_pages
= 0;
2491 if (!nr_args
|| nr_args
> UIO_MAXIOV
)
2494 ctx
->user_bufs
= kcalloc(nr_args
, sizeof(struct io_mapped_ubuf
),
2496 if (!ctx
->user_bufs
)
2499 for (i
= 0; i
< nr_args
; i
++) {
2500 struct io_mapped_ubuf
*imu
= &ctx
->user_bufs
[i
];
2501 unsigned long off
, start
, end
, ubuf
;
2506 ret
= io_copy_iov(ctx
, &iov
, arg
, i
);
2511 * Don't impose further limits on the size and buffer
2512 * constraints here, we'll -EINVAL later when IO is
2513 * submitted if they are wrong.
2516 if (!iov
.iov_base
|| !iov
.iov_len
)
2519 /* arbitrary limit, but we need something */
2520 if (iov
.iov_len
> SZ_1G
)
2523 ubuf
= (unsigned long) iov
.iov_base
;
2524 end
= (ubuf
+ iov
.iov_len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
2525 start
= ubuf
>> PAGE_SHIFT
;
2526 nr_pages
= end
- start
;
2528 if (ctx
->account_mem
) {
2529 ret
= io_account_mem(ctx
->user
, nr_pages
);
2535 if (!pages
|| nr_pages
> got_pages
) {
2538 pages
= kvmalloc_array(nr_pages
, sizeof(struct page
*),
2540 vmas
= kvmalloc_array(nr_pages
,
2541 sizeof(struct vm_area_struct
*),
2543 if (!pages
|| !vmas
) {
2545 if (ctx
->account_mem
)
2546 io_unaccount_mem(ctx
->user
, nr_pages
);
2549 got_pages
= nr_pages
;
2552 imu
->bvec
= kvmalloc_array(nr_pages
, sizeof(struct bio_vec
),
2556 if (ctx
->account_mem
)
2557 io_unaccount_mem(ctx
->user
, nr_pages
);
2562 down_read(¤t
->mm
->mmap_sem
);
2563 pret
= get_user_pages_longterm(ubuf
, nr_pages
, FOLL_WRITE
,
2565 if (pret
== nr_pages
) {
2566 /* don't support file backed memory */
2567 for (j
= 0; j
< nr_pages
; j
++) {
2568 struct vm_area_struct
*vma
= vmas
[j
];
2571 !is_file_hugepages(vma
->vm_file
)) {
2577 ret
= pret
< 0 ? pret
: -EFAULT
;
2579 up_read(¤t
->mm
->mmap_sem
);
2582 * if we did partial map, or found file backed vmas,
2583 * release any pages we did get
2586 for (j
= 0; j
< pret
; j
++)
2589 if (ctx
->account_mem
)
2590 io_unaccount_mem(ctx
->user
, nr_pages
);
2595 off
= ubuf
& ~PAGE_MASK
;
2597 for (j
= 0; j
< nr_pages
; j
++) {
2600 vec_len
= min_t(size_t, size
, PAGE_SIZE
- off
);
2601 imu
->bvec
[j
].bv_page
= pages
[j
];
2602 imu
->bvec
[j
].bv_len
= vec_len
;
2603 imu
->bvec
[j
].bv_offset
= off
;
2607 /* store original address for later verification */
2609 imu
->len
= iov
.iov_len
;
2610 imu
->nr_bvecs
= nr_pages
;
2612 ctx
->nr_user_bufs
++;
2620 io_sqe_buffer_unregister(ctx
);
2624 static void io_ring_ctx_free(struct io_ring_ctx
*ctx
)
2626 io_finish_async(ctx
);
2628 mmdrop(ctx
->sqo_mm
);
2630 io_iopoll_reap_events(ctx
);
2631 io_sqe_buffer_unregister(ctx
);
2632 io_sqe_files_unregister(ctx
);
2634 #if defined(CONFIG_UNIX)
2636 sock_release(ctx
->ring_sock
);
2639 io_mem_free(ctx
->sq_ring
);
2640 io_mem_free(ctx
->sq_sqes
);
2641 io_mem_free(ctx
->cq_ring
);
2643 percpu_ref_exit(&ctx
->refs
);
2644 if (ctx
->account_mem
)
2645 io_unaccount_mem(ctx
->user
,
2646 ring_pages(ctx
->sq_entries
, ctx
->cq_entries
));
2647 free_uid(ctx
->user
);
2651 static __poll_t
io_uring_poll(struct file
*file
, poll_table
*wait
)
2653 struct io_ring_ctx
*ctx
= file
->private_data
;
2656 poll_wait(file
, &ctx
->cq_wait
, wait
);
2658 * synchronizes with barrier from wq_has_sleeper call in
2662 if (READ_ONCE(ctx
->sq_ring
->r
.tail
) - ctx
->cached_sq_head
!=
2663 ctx
->sq_ring
->ring_entries
)
2664 mask
|= EPOLLOUT
| EPOLLWRNORM
;
2665 if (READ_ONCE(ctx
->cq_ring
->r
.head
) != ctx
->cached_cq_tail
)
2666 mask
|= EPOLLIN
| EPOLLRDNORM
;
2671 static int io_uring_fasync(int fd
, struct file
*file
, int on
)
2673 struct io_ring_ctx
*ctx
= file
->private_data
;
2675 return fasync_helper(fd
, file
, on
, &ctx
->cq_fasync
);
2678 static void io_ring_ctx_wait_and_kill(struct io_ring_ctx
*ctx
)
2680 mutex_lock(&ctx
->uring_lock
);
2681 percpu_ref_kill(&ctx
->refs
);
2682 mutex_unlock(&ctx
->uring_lock
);
2684 io_poll_remove_all(ctx
);
2685 io_iopoll_reap_events(ctx
);
2686 wait_for_completion(&ctx
->ctx_done
);
2687 io_ring_ctx_free(ctx
);
2690 static int io_uring_release(struct inode
*inode
, struct file
*file
)
2692 struct io_ring_ctx
*ctx
= file
->private_data
;
2694 file
->private_data
= NULL
;
2695 io_ring_ctx_wait_and_kill(ctx
);
2699 static int io_uring_mmap(struct file
*file
, struct vm_area_struct
*vma
)
2701 loff_t offset
= (loff_t
) vma
->vm_pgoff
<< PAGE_SHIFT
;
2702 unsigned long sz
= vma
->vm_end
- vma
->vm_start
;
2703 struct io_ring_ctx
*ctx
= file
->private_data
;
2709 case IORING_OFF_SQ_RING
:
2712 case IORING_OFF_SQES
:
2715 case IORING_OFF_CQ_RING
:
2722 page
= virt_to_head_page(ptr
);
2723 if (sz
> (PAGE_SIZE
<< compound_order(page
)))
2726 pfn
= virt_to_phys(ptr
) >> PAGE_SHIFT
;
2727 return remap_pfn_range(vma
, vma
->vm_start
, pfn
, sz
, vma
->vm_page_prot
);
2730 SYSCALL_DEFINE6(io_uring_enter
, unsigned int, fd
, u32
, to_submit
,
2731 u32
, min_complete
, u32
, flags
, const sigset_t __user
*, sig
,
2734 struct io_ring_ctx
*ctx
;
2739 if (flags
& ~(IORING_ENTER_GETEVENTS
| IORING_ENTER_SQ_WAKEUP
))
2747 if (f
.file
->f_op
!= &io_uring_fops
)
2751 ctx
= f
.file
->private_data
;
2752 if (!percpu_ref_tryget(&ctx
->refs
))
2756 * For SQ polling, the thread will do all submissions and completions.
2757 * Just return the requested submit count, and wake the thread if
2760 if (ctx
->flags
& IORING_SETUP_SQPOLL
) {
2761 if (flags
& IORING_ENTER_SQ_WAKEUP
)
2762 wake_up(&ctx
->sqo_wait
);
2763 submitted
= to_submit
;
2769 to_submit
= min(to_submit
, ctx
->sq_entries
);
2771 mutex_lock(&ctx
->uring_lock
);
2772 submitted
= io_ring_submit(ctx
, to_submit
);
2773 mutex_unlock(&ctx
->uring_lock
);
2775 if (flags
& IORING_ENTER_GETEVENTS
) {
2776 unsigned nr_events
= 0;
2778 min_complete
= min(min_complete
, ctx
->cq_entries
);
2780 if (ctx
->flags
& IORING_SETUP_IOPOLL
) {
2781 mutex_lock(&ctx
->uring_lock
);
2782 ret
= io_iopoll_check(ctx
, &nr_events
, min_complete
);
2783 mutex_unlock(&ctx
->uring_lock
);
2785 ret
= io_cqring_wait(ctx
, min_complete
, sig
, sigsz
);
2790 io_ring_drop_ctx_refs(ctx
, 1);
2793 return submitted
? submitted
: ret
;
2796 static const struct file_operations io_uring_fops
= {
2797 .release
= io_uring_release
,
2798 .mmap
= io_uring_mmap
,
2799 .poll
= io_uring_poll
,
2800 .fasync
= io_uring_fasync
,
2803 static int io_allocate_scq_urings(struct io_ring_ctx
*ctx
,
2804 struct io_uring_params
*p
)
2806 struct io_sq_ring
*sq_ring
;
2807 struct io_cq_ring
*cq_ring
;
2810 sq_ring
= io_mem_alloc(struct_size(sq_ring
, array
, p
->sq_entries
));
2814 ctx
->sq_ring
= sq_ring
;
2815 sq_ring
->ring_mask
= p
->sq_entries
- 1;
2816 sq_ring
->ring_entries
= p
->sq_entries
;
2817 ctx
->sq_mask
= sq_ring
->ring_mask
;
2818 ctx
->sq_entries
= sq_ring
->ring_entries
;
2820 size
= array_size(sizeof(struct io_uring_sqe
), p
->sq_entries
);
2821 if (size
== SIZE_MAX
)
2824 ctx
->sq_sqes
= io_mem_alloc(size
);
2828 cq_ring
= io_mem_alloc(struct_size(cq_ring
, cqes
, p
->cq_entries
));
2832 ctx
->cq_ring
= cq_ring
;
2833 cq_ring
->ring_mask
= p
->cq_entries
- 1;
2834 cq_ring
->ring_entries
= p
->cq_entries
;
2835 ctx
->cq_mask
= cq_ring
->ring_mask
;
2836 ctx
->cq_entries
= cq_ring
->ring_entries
;
2841 * Allocate an anonymous fd, this is what constitutes the application
2842 * visible backing of an io_uring instance. The application mmaps this
2843 * fd to gain access to the SQ/CQ ring details. If UNIX sockets are enabled,
2844 * we have to tie this fd to a socket for file garbage collection purposes.
2846 static int io_uring_get_fd(struct io_ring_ctx
*ctx
)
2851 #if defined(CONFIG_UNIX)
2852 ret
= sock_create_kern(&init_net
, PF_UNIX
, SOCK_RAW
, IPPROTO_IP
,
2858 ret
= get_unused_fd_flags(O_RDWR
| O_CLOEXEC
);
2862 file
= anon_inode_getfile("[io_uring]", &io_uring_fops
, ctx
,
2863 O_RDWR
| O_CLOEXEC
);
2866 ret
= PTR_ERR(file
);
2870 #if defined(CONFIG_UNIX)
2871 ctx
->ring_sock
->file
= file
;
2872 ctx
->ring_sock
->sk
->sk_user_data
= ctx
;
2874 fd_install(ret
, file
);
2877 #if defined(CONFIG_UNIX)
2878 sock_release(ctx
->ring_sock
);
2879 ctx
->ring_sock
= NULL
;
2884 static int io_uring_create(unsigned entries
, struct io_uring_params
*p
)
2886 struct user_struct
*user
= NULL
;
2887 struct io_ring_ctx
*ctx
;
2891 if (!entries
|| entries
> IORING_MAX_ENTRIES
)
2895 * Use twice as many entries for the CQ ring. It's possible for the
2896 * application to drive a higher depth than the size of the SQ ring,
2897 * since the sqes are only used at submission time. This allows for
2898 * some flexibility in overcommitting a bit.
2900 p
->sq_entries
= roundup_pow_of_two(entries
);
2901 p
->cq_entries
= 2 * p
->sq_entries
;
2903 user
= get_uid(current_user());
2904 account_mem
= !capable(CAP_IPC_LOCK
);
2907 ret
= io_account_mem(user
,
2908 ring_pages(p
->sq_entries
, p
->cq_entries
));
2915 ctx
= io_ring_ctx_alloc(p
);
2918 io_unaccount_mem(user
, ring_pages(p
->sq_entries
,
2923 ctx
->compat
= in_compat_syscall();
2924 ctx
->account_mem
= account_mem
;
2927 ret
= io_allocate_scq_urings(ctx
, p
);
2931 ret
= io_sq_offload_start(ctx
, p
);
2935 ret
= io_uring_get_fd(ctx
);
2939 memset(&p
->sq_off
, 0, sizeof(p
->sq_off
));
2940 p
->sq_off
.head
= offsetof(struct io_sq_ring
, r
.head
);
2941 p
->sq_off
.tail
= offsetof(struct io_sq_ring
, r
.tail
);
2942 p
->sq_off
.ring_mask
= offsetof(struct io_sq_ring
, ring_mask
);
2943 p
->sq_off
.ring_entries
= offsetof(struct io_sq_ring
, ring_entries
);
2944 p
->sq_off
.flags
= offsetof(struct io_sq_ring
, flags
);
2945 p
->sq_off
.dropped
= offsetof(struct io_sq_ring
, dropped
);
2946 p
->sq_off
.array
= offsetof(struct io_sq_ring
, array
);
2948 memset(&p
->cq_off
, 0, sizeof(p
->cq_off
));
2949 p
->cq_off
.head
= offsetof(struct io_cq_ring
, r
.head
);
2950 p
->cq_off
.tail
= offsetof(struct io_cq_ring
, r
.tail
);
2951 p
->cq_off
.ring_mask
= offsetof(struct io_cq_ring
, ring_mask
);
2952 p
->cq_off
.ring_entries
= offsetof(struct io_cq_ring
, ring_entries
);
2953 p
->cq_off
.overflow
= offsetof(struct io_cq_ring
, overflow
);
2954 p
->cq_off
.cqes
= offsetof(struct io_cq_ring
, cqes
);
2957 io_ring_ctx_wait_and_kill(ctx
);
2962 * Sets up an aio uring context, and returns the fd. Applications asks for a
2963 * ring size, we return the actual sq/cq ring sizes (among other things) in the
2964 * params structure passed in.
2966 static long io_uring_setup(u32 entries
, struct io_uring_params __user
*params
)
2968 struct io_uring_params p
;
2972 if (copy_from_user(&p
, params
, sizeof(p
)))
2974 for (i
= 0; i
< ARRAY_SIZE(p
.resv
); i
++) {
2979 if (p
.flags
& ~(IORING_SETUP_IOPOLL
| IORING_SETUP_SQPOLL
|
2980 IORING_SETUP_SQ_AFF
))
2983 ret
= io_uring_create(entries
, &p
);
2987 if (copy_to_user(params
, &p
, sizeof(p
)))
2993 SYSCALL_DEFINE2(io_uring_setup
, u32
, entries
,
2994 struct io_uring_params __user
*, params
)
2996 return io_uring_setup(entries
, params
);
2999 static int __io_uring_register(struct io_ring_ctx
*ctx
, unsigned opcode
,
3000 void __user
*arg
, unsigned nr_args
)
3001 __releases(ctx
->uring_lock
)
3002 __acquires(ctx
->uring_lock
)
3007 * We're inside the ring mutex, if the ref is already dying, then
3008 * someone else killed the ctx or is already going through
3009 * io_uring_register().
3011 if (percpu_ref_is_dying(&ctx
->refs
))
3014 percpu_ref_kill(&ctx
->refs
);
3017 * Drop uring mutex before waiting for references to exit. If another
3018 * thread is currently inside io_uring_enter() it might need to grab
3019 * the uring_lock to make progress. If we hold it here across the drain
3020 * wait, then we can deadlock. It's safe to drop the mutex here, since
3021 * no new references will come in after we've killed the percpu ref.
3023 mutex_unlock(&ctx
->uring_lock
);
3024 wait_for_completion(&ctx
->ctx_done
);
3025 mutex_lock(&ctx
->uring_lock
);
3028 case IORING_REGISTER_BUFFERS
:
3029 ret
= io_sqe_buffer_register(ctx
, arg
, nr_args
);
3031 case IORING_UNREGISTER_BUFFERS
:
3035 ret
= io_sqe_buffer_unregister(ctx
);
3037 case IORING_REGISTER_FILES
:
3038 ret
= io_sqe_files_register(ctx
, arg
, nr_args
);
3040 case IORING_UNREGISTER_FILES
:
3044 ret
= io_sqe_files_unregister(ctx
);
3051 /* bring the ctx back to life */
3052 reinit_completion(&ctx
->ctx_done
);
3053 percpu_ref_reinit(&ctx
->refs
);
3057 SYSCALL_DEFINE4(io_uring_register
, unsigned int, fd
, unsigned int, opcode
,
3058 void __user
*, arg
, unsigned int, nr_args
)
3060 struct io_ring_ctx
*ctx
;
3069 if (f
.file
->f_op
!= &io_uring_fops
)
3072 ctx
= f
.file
->private_data
;
3074 mutex_lock(&ctx
->uring_lock
);
3075 ret
= __io_uring_register(ctx
, opcode
, arg
, nr_args
);
3076 mutex_unlock(&ctx
->uring_lock
);
3082 static int __init
io_uring_init(void)
3084 req_cachep
= KMEM_CACHE(io_kiocb
, SLAB_HWCACHE_ALIGN
| SLAB_PANIC
);
3087 __initcall(io_uring_init
);