vsock/virtio: set SOCK_DONE on peer shutdown

Set the SOCK_DONE flag to match the TCP_CLOSING state when a peer has
shut down and there is nothing left to read.

This fixes the following bug:
1) Peer sends SHUTDOWN(RDWR).
2) Socket enters TCP_CLOSING but SOCK_DONE is not set.
3) read() returns -ENOTCONN until close() is called, then returns 0.
Signed-off-by: Stephen Barber <smbarber@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/vmw_vsock/virtio_transport_common.c

@@ -871,8 +871,10 @@ virtio_transport_recv_connected(struct sock *sk,
 		if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SHUTDOWN_SEND)
 			vsk->peer_shutdown |= SEND_SHUTDOWN;
 		if (vsk->peer_shutdown == SHUTDOWN_MASK &&
-		    vsock_stream_has_data(vsk) <= 0)
+		    vsock_stream_has_data(vsk) <= 0) {
+			sock_set_flag(sk, SOCK_DONE);
 			sk->sk_state = TCP_CLOSING;
+		}
 		if (le32_to_cpu(pkt->hdr.flags))
 			sk->sk_state_change(sk);
 		break;