Commit 59850d22 authored Dec 06, 2020 by Pavel Begunkov Committed by Jens Axboe Dec 09, 2020

io_uring: fix io_cqring_events()'s noflush



Checking !list_empty(&ctx->cq_overflow_list) around noflush in
io_cqring_events() is racy, because if it fails but a request overflowed
just after that, io_cqring_overflow_flush() still will be called.

Remove the second check, it shouldn't be a problem for performance,
because there is cq_check_overflow bit check just above.

Cc: <stable@vger.kernel.org> # 5.5+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 634578f8

fs/io_uring.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2329,7 +2329,7 @@ static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush)
		* we wake up the task, and the next invocation will flush the
		* entries. We cannot safely to it from here.
		*/
		if (noflush && !list_empty(&ctx->cq_overflow_list))
		if (noflush)
		return -1U;

		io_cqring_overflow_flush(ctx, false, NULL, NULL);

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