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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Stefan Metzmacher <metze@samba.org>,
        Pavel Begunkov <asml.silence@gmail.com>,
        Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 6.0 846/862] io_uring/net: dont skip notifs for failed requests
Date:   Wed, 19 Oct 2022 10:35:33 +0200
Message-Id: <20221019083327.264626413@linuxfoundation.org>
In-Reply-To: <20221019083249.951566199@linuxfoundation.org>
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From: Pavel Begunkov <asml.silence@gmail.com>

[ upstream commit 6ae91ac9a6aa7d6005c3c6d0f4d263fbab9f377f ]

We currently only add a notification CQE when the send succeded, i.e.
cqe.res >= 0. However, it'd be more robust to do buffer notifications
for failed requests as well in case drivers decide do something fanky.

Always return a buffer notification after initial prep, don't hide it.
This behaviour is better aligned with documentation and the patch also
helps the userspace to respect it.

Cc: stable@vger.kernel.org # 6.0
Suggested-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9c8bead87b2b980fcec441b8faef52188b4a6588.1664292100.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 io_uring/net.c |   22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -879,7 +879,6 @@ void io_send_zc_cleanup(struct io_kiocb
 {
 	struct io_sr_msg *zc = io_kiocb_to_cmd(req, struct io_sr_msg);
 
-	zc->notif->flags |= REQ_F_CQE_SKIP;
 	io_notif_flush(zc->notif);
 	zc->notif = NULL;
 }
@@ -996,7 +995,7 @@ int io_send_zc(struct io_kiocb *req, uns
 	struct msghdr msg;
 	struct iovec iov;
 	struct socket *sock;
-	unsigned msg_flags, cflags;
+	unsigned msg_flags;
 	int ret, min_ret = 0;
 
 	sock = sock_from_file(req->file);
@@ -1064,8 +1063,6 @@ int io_send_zc(struct io_kiocb *req, uns
 			req->flags |= REQ_F_PARTIAL_IO;
 			return io_setup_async_addr(req, addr, issue_flags);
 		}
-		if (ret < 0 && !zc->done_io)
-			zc->notif->flags |= REQ_F_CQE_SKIP;
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
 		req_set_fail(req);
@@ -1078,8 +1075,7 @@ int io_send_zc(struct io_kiocb *req, uns
 
 	io_notif_flush(zc->notif);
 	req->flags &= ~REQ_F_NEED_CLEANUP;
-	cflags = ret >= 0 ? IORING_CQE_F_MORE : 0;
-	io_req_set_res(req, ret, cflags);
+	io_req_set_res(req, ret, IORING_CQE_F_MORE);
 	return IOU_OK;
 }
 
@@ -1096,17 +1092,11 @@ void io_sendrecv_fail(struct io_kiocb *r
 void io_send_zc_fail(struct io_kiocb *req)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
-	int res = req->cqe.res;
 
-	if (req->flags & REQ_F_PARTIAL_IO) {
-		if (req->flags & REQ_F_NEED_CLEANUP) {
-			io_notif_flush(sr->notif);
-			sr->notif = NULL;
-			req->flags &= ~REQ_F_NEED_CLEANUP;
-		}
-		res = sr->done_io;
-	}
-	io_req_set_res(req, res, req->cqe.flags);
+	if (req->flags & REQ_F_PARTIAL_IO)
+		req->cqe.res = sr->done_io;
+	if (req->flags & REQ_F_NEED_CLEANUP)
+		req->cqe.flags |= IORING_CQE_F_MORE;
 }
 
 int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)