netdev - [PATCH 3.16 316/370] VSOCK: do not disconnect socket when peer has shutdown SEND only

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Date:   Fri, 10 Mar 2017 11:46:23 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Adit Ranadive" <aditr@...are.com>,
        "Dmitry Torokhov" <dtor@...are.com>,
        "Stefan Hajnoczi" <stefanha@...hat.com>,
        "Jorgen Hansen" <jhansen@...are.com>,
        "David S. Miller" <davem@...emloft.net>,
        "Claudio Imbrenda" <imbrenda@...ux.vnet.ibm.com>,
        "Ian Campbell" <ian.campbell@...ker.com>, netdev@...r.kernel.org,
        "Andy King" <acking@...are.com>
Subject: [PATCH 3.16 316/370] VSOCK: do not disconnect socket when peer
 has shutdown  SEND only

3.16.42-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ian Campbell <ian.campbell@...ker.com>

[ Upstream commit dedc58e067d8c379a15a8a183c5db318201295bb ]

The peer may be expecting a reply having sent a request and then done a
shutdown(SHUT_WR), so tearing down the whole socket at this point seems
wrong and breaks for me with a client which does a SHUT_WR.

Looking at other socket family's stream_recvmsg callbacks doing a shutdown
here does not seem to be the norm and removing it does not seem to have
had any adverse effects that I can see.

I'm using Stefan's RFC virtio transport patches, I'm unsure of the impact
on the vmci transport.

Signed-off-by: Ian Campbell <ian.campbell@...ker.com>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Stefan Hajnoczi <stefanha@...hat.com>
Cc: Claudio Imbrenda <imbrenda@...ux.vnet.ibm.com>
Cc: Andy King <acking@...are.com>
Cc: Dmitry Torokhov <dtor@...are.com>
Cc: Jorgen Hansen <jhansen@...are.com>
Cc: Adit Ranadive <aditr@...are.com>
Cc: netdev@...r.kernel.org
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/vmw_vsock/af_vsock.c | 21 +--------------------
 1 file changed, 1 insertion(+), 20 deletions(-)

--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1796,27 +1796,8 @@ vsock_stream_recvmsg(struct kiocb *kiocb
 	else if (sk->sk_shutdown & RCV_SHUTDOWN)
 		err = 0;
 
-	if (copied > 0) {
-		/* We only do these additional bookkeeping/notification steps
-		 * if we actually copied something out of the queue pair
-		 * instead of just peeking ahead.
-		 */
-
-		if (!(flags & MSG_PEEK)) {
-			/* If the other side has shutdown for sending and there
-			 * is nothing more to read, then modify the socket
-			 * state.
-			 */
-			if (vsk->peer_shutdown & SEND_SHUTDOWN) {
-				if (vsock_stream_has_data(vsk) <= 0) {
-					sk->sk_state = SS_UNCONNECTED;
-					sock_set_flag(sk, SOCK_DONE);
-					sk->sk_state_change(sk);
-				}
-			}
-		}
+	if (copied > 0)
 		err = copied;
-	}
 
 out_wait:
 	finish_wait(sk_sleep(sk), &wait);