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io_uring: fix io_cqring_events()'s noflush

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commit 59850d226e upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pavel Begunkov 2020-12-06 22:22:45 +00:00 committed by Greg Kroah-Hartman
parent 54677c80ba
commit 821d12a15c
1 changed files with 1 additions and 1 deletions
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2
fs/io_uring.c
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@ -2242,7 +2242,7 @@ 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);