netdev - Re: [PATCH] VSOCK: do not disconnect socket when peer has shutdown SEND only

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Date:	Thu, 5 May 2016 19:23:45 +0100
From:	Stefan Hajnoczi <stefanha@...hat.com>
To:	Ian Campbell <ian.campbell@...ker.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Claudio Imbrenda <imbrenda@...ux.vnet.ibm.com>,
	Andy King <acking@...are.com>,
	Dmitry Torokhov <dtor@...are.com>,
	Jorgen Hansen <jhansen@...are.com>,
	Adit Ranadive <aditr@...are.com>
Subject: Re: [PATCH] VSOCK: do not disconnect socket when peer has shutdown
 SEND only

On Wed, May 04, 2016 at 02:21:53PM +0100, Ian Campbell wrote:
> 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.

Seems fine to me.

> 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
> ---
>  net/vmw_vsock/af_vsock.c | 21 +--------------------
>  1 file changed, 1 insertion(+), 20 deletions(-)
> 
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 1e5f5ed..7a25150 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -1789,27 +1789,8 @@ vsock_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
>  	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:
>  	release_sock(sk);
> -- 
> 2.8.1
> 

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