Commit 7c504e65 authored Dec 18, 2019 by Pavel Begunkov Committed by Jens Axboe Dec 18, 2019

io_uring: don't wait when under-submitting



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>

parent e781573e

fs/io_uring.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -5135,6 +5135,9 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
		submitted = io_submit_sqes(ctx, to_submit, f.file, fd,
		&cur_mm, false);
		mutex_unlock(&ctx->uring_lock);

		if (submitted != to_submit)
		goto out;
		}
		if (flags & IORING_ENTER_GETEVENTS) {
		unsigned nr_events = 0;
		@@ -5148,6 +5151,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
		}
		}

		out:
		percpu_ref_put(&ctx->refs);
		out_fput:
		fdput(f);

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