io_uring: improve poll warning handling

Don't try to complete requests if their refs are broken and we've got
a warning, it's much better to drop them and potentially leaking than
double freeing.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/31edf9f96f05d03ab62c114508a231a2dce434cb.1669821213.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/poll.c

@@ -249,7 +249,7 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
 		if (unlikely(v != 1)) {
 			/* tw should be the owner and so have some refs */
 			if (WARN_ON_ONCE(!(v & IO_POLL_REF_MASK)))
-				return IOU_POLL_DONE;
+				return IOU_POLL_NO_ACTION;
 			if (v & IO_POLL_CANCEL_FLAG)
 				return -ECANCELED;
 			/*