io_uring: transform send/recvmsg() -ERESTARTSYS to -EINTR

We should never return -ERESTARTSYS to userspace, transform it into
-EINTR.

Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1917,6 +1917,8 @@ static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		ret = fn(sock, msg, flags);
 		if (force_nonblock && ret == -EAGAIN)
 			return ret;
+		if (ret == -ERESTARTSYS)
+			ret = -EINTR;
 	}
 
 	io_cqring_add_event(req, ret);