diff mbox series

[5.10,510/717] io_uring: fix io_cqring_events()s noflush

Message ID 20201228125045.395675197@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Dec. 28, 2020, 12:48 p.m. UTC 
From: Pavel Begunkov <asml.silence@gmail.com>

commit 59850d226e4907a6f37c1d2fe5ba97546a8691a4 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>

---
 fs/io_uring.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2242,7 +2242,7 @@  static unsigned io_cqring_events(struct
 		 * 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);