netdev - [PATCH] VSOCK: set POLLOUT | POLLWRNORM for TCP

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Date:   Fri, 26 Jan 2018 11:48:25 +0000
From:   Stefan Hajnoczi <stefanha@...hat.com>
To:     netdev@...r.kernel.org
Cc:     Dexuan Cui <decui@...rosoft.com>,
        Jorgen Hansen <jhansen@...are.com>,
        Stefan Hajnoczi <stefanha@...hat.com>
Subject: [PATCH] VSOCK: set POLLOUT | POLLWRNORM for TCP_CLOSING

select(2) with wfds but no rfds must return when the socket is shut down
by the peer.  This way userspace notices socket activity and gets -EPIPE
from the next write(2).

Currently select(2) does not return for virtio-vsock when a SEND+RCV
shutdown packet is received.  This is because vsock_poll() only sets
POLLOUT | POLLWRNORM for TCP_CLOSE, not the TCP_CLOSING state that the
socket is in when the shutdown is received.

Signed-off-by: Stefan Hajnoczi <stefanha@...hat.com>
---
 net/vmw_vsock/af_vsock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 5d28abf87fbf..c9473d698525 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -951,7 +951,7 @@ static unsigned int vsock_poll(struct file *file, struct socket *sock,
 		 * POLLOUT|POLLWRNORM when peer is closed and nothing to read,
 		 * but local send is not shutdown.
 		 */
-		if (sk->sk_state == TCP_CLOSE) {
+		if (sk->sk_state == TCP_CLOSE || sk->sk_state == TCP_CLOSING) {
 			if (!(sk->sk_shutdown & SEND_SHUTDOWN))
 				mask |= POLLOUT | POLLWRNORM;
 
-- 
2.14.3