io_uring: don't check iopoll if request completes

commit 9b43ef3d52532a0175ed6654618f7db61d390d2e upstream.

IOPOLL request should never return IOU_OK, so the following iopoll
queueing check in io_issue_sqe() after getting IOU_OK doesn't make any
sense as would never turn true. Let's optimise on that and return a bit
earlier. It's also much more resilient to potential bugs from
mischieving iopoll implementations.

Cc:  <stable@vger.kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2f8690e2fa5213a2ff292fac29a7143c036cdd60.1701390926.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 586ac65..b406cc6 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1891,7 +1891,11 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
                        io_req_complete_defer(req);
                else
                        io_req_complete_post(req, issue_flags);
-       } else if (ret != IOU_ISSUE_SKIP_COMPLETE)
+
+               return 0;
+       }
+
+       if (ret != IOU_ISSUE_SKIP_COMPLETE)
                return ret;
 
        /* If the op doesn't have a file, we're not polling for it */