| From b22988335618046bcfe00734ed739c6f369b66b9 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Wed, 18 Dec 2019 19:53:45 +0300 |
| Subject: io_uring: don't wait when under-submitting |
| |
| From: Pavel Begunkov <asml.silence@gmail.com> |
| |
| [ Upstream commit 7c504e65206a4379ff38fe41d21b32b6c2c3e53e ] |
| |
| There is no reliable way to submit and wait in a single syscall, as |
| io_submit_sqes() may under-consume sqes (in case of an early error). |
| Then it will wait for not-yet-submitted requests, deadlocking the user |
| in most cases. |
| |
| Don't wait/poll if can't submit all sqes |
| |
| Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> |
| Signed-off-by: Jens Axboe <axboe@kernel.dk> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| fs/io_uring.c | 4 ++++ |
| 1 file changed, 4 insertions(+) |
| |
| diff --git a/fs/io_uring.c b/fs/io_uring.c |
| index a60c6315a348..709671faaed6 100644 |
| --- a/fs/io_uring.c |
| +++ b/fs/io_uring.c |
| @@ -3721,6 +3721,9 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, |
| mutex_lock(&ctx->uring_lock); |
| submitted = io_ring_submit(ctx, to_submit); |
| mutex_unlock(&ctx->uring_lock); |
| + |
| + if (submitted != to_submit) |
| + goto out; |
| } |
| if (flags & IORING_ENTER_GETEVENTS) { |
| unsigned nr_events = 0; |
| @@ -3734,6 +3737,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, |
| } |
| } |
| |
| +out: |
| percpu_ref_put(&ctx->refs); |
| out_fput: |
| fdput(f); |
| -- |
| 2.20.1 |
| |
