[PATCHv3,net-next] sctp: sctp should change socket state when shutdown is received

Now sctp doesn't change socket state upon shutdown reception. It changes
just the assoc state, even though it's a TCP-style socket.

For some cases, if we really need to check sk->sk_state, it's necessary to
fix this issue, at least when we use ss or netstat to dump, we can get a
more exact information.

As an improvement, we will change sk->sk_state when we change asoc->state
to SHUTDOWN_RECEIVED, and also do it in sctp_shutdown to keep consistent with
sctp_close.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/sctp/sm_sideeffect.c | 4 +++-
 net/sctp/socket.c        | 7 +++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

On Thu, Jun 09, 2016 at 07:22:16PM +0800, Xin Long wrote:
> Now sctp doesn't change socket state upon shutdown reception. It changes
> just the assoc state, even though it's a TCP-style socket.
> 
> For some cases, if we really need to check sk->sk_state, it's necessary to
> fix this issue, at least when we use ss or netstat to dump, we can get a
> more exact information.
> 
> As an improvement, we will change sk->sk_state when we change asoc->state
> to SHUTDOWN_RECEIVED, and also do it in sctp_shutdown to keep consistent with
> sctp_close.
> 
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
> ---
>  net/sctp/sm_sideeffect.c | 4 +++-
>  net/sctp/socket.c        | 7 +++++--
>  2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
> index aa37122..12d4519 100644
> --- a/net/sctp/sm_sideeffect.c
> +++ b/net/sctp/sm_sideeffect.c
> @@ -806,8 +806,10 @@ static void sctp_cmd_new_state(sctp_cmd_seq_t *cmds,
>  
>  		/* Set the RCV_SHUTDOWN flag when a SHUTDOWN is received. */
>  		if (sctp_state(asoc, SHUTDOWN_RECEIVED) &&
> -		    sctp_sstate(sk, ESTABLISHED))
> +		    sctp_sstate(sk, ESTABLISHED)) {
> +			sk->sk_state = SCTP_SS_CLOSING;
>  			sk->sk_shutdown |= RCV_SHUTDOWN;
> +		}
>  	}
>  
>  	if (sctp_state(asoc, COOKIE_WAIT)) {
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 67154b8..80d860a 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -4193,6 +4193,7 @@ static void sctp_shutdown(struct sock *sk, int how)
>  		return;
>  
>  	if (how & SEND_SHUTDOWN) {
> +		sk->sk_state = SCTP_SS_CLOSING;
>  		ep = sctp_sk(sk)->ep;
>  		if (!list_empty(&ep->asocs)) {
>  			asoc = list_entry(ep->asocs.next,
> @@ -7564,10 +7565,12 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
>  	/* If the association on the newsk is already closed before accept()
>  	 * is called, set RCV_SHUTDOWN flag.
>  	 */
> -	if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP))
> +	if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP)) {
> +		newsk->sk_state = SCTP_SS_CLOSING;
>  		newsk->sk_shutdown |= RCV_SHUTDOWN;
> +	} else
> +		newsk->sk_state = SCTP_SS_ESTABLISHED;
>  
> -	newsk->sk_state = SCTP_SS_ESTABLISHED;
>  	release_sock(newsk);
>  }
>  

checkpatch is giving a warning here:
WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
#85: 
to SHUTDOWN_RECEIVED, and also do it in sctp_shutdown to keep consistent with

CHECK: braces {} should be used on all arms of this statement
#127: FILE: net/sctp/socket.c:7568:
+	if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP)) {
[...]
+	} else

Other than that changes LGTM, but please fix this. Thanks

  Marcelo

Hello.

On 6/9/2016 2:22 PM, Xin Long wrote:

> Now sctp doesn't change socket state upon shutdown reception. It changes
> just the assoc state, even though it's a TCP-style socket.
>
> For some cases, if we really need to check sk->sk_state, it's necessary to
> fix this issue, at least when we use ss or netstat to dump, we can get a
> more exact information.
>
> As an improvement, we will change sk->sk_state when we change asoc->state
> to SHUTDOWN_RECEIVED, and also do it in sctp_shutdown to keep consistent with
> sctp_close.
>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
[...]
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 67154b8..80d860a 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
[...]
> @@ -7564,10 +7565,12 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
>  	/* If the association on the newsk is already closed before accept()
>  	 * is called, set RCV_SHUTDOWN flag.
>  	 */
> -	if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP))
> +	if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP)) {
> +		newsk->sk_state = SCTP_SS_CLOSING;
>  		newsk->sk_shutdown |= RCV_SHUTDOWN;
> +	} else
> +		newsk->sk_state = SCTP_SS_ESTABLISHED;

    CodingStyle: all arms of the *if* statment should use {} if at least one 
arm uses {}.

MBR, Sergei