io_uring: fix async accept on O_NONBLOCK sockets

commit a73825ba70c93e1eb39a845bb3d9885a787f8ffe upstream.

Do not set REQ_F_NOWAIT if the socket is non blocking. When enabled this
causes the accept to immediately post a CQE with EAGAIN, which means you
cannot perform an accept SQE on a NONBLOCK socket asynchronously.

By removing the flag if there is no pending accept then poll is armed as
usual and when a connection comes in the CQE is posted.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220324143435.2875844-1-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 997a726..e1e15d4 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -5272,9 +5272,6 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags)
        struct file *file;
        int ret, fd;
 
-       if (req->file->f_flags & O_NONBLOCK)
-               req->flags |= REQ_F_NOWAIT;
-
        if (!fixed) {
                fd = __get_unused_fd_flags(accept->flags, accept->nofile);
                if (unlikely(fd < 0))
@@ -5286,6 +5283,8 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags)
                if (!fixed)
                        put_unused_fd(fd);
                ret = PTR_ERR(file);
+               /* safe to retry */
+               req->flags |= REQ_F_PARTIAL_IO;
                if (ret == -EAGAIN && force_nonblock)
                        return -EAGAIN;
                if (ret == -ERESTARTSYS)