netdev - Re: [PATCHv3] sctp: ABORT if receive, reassmbly, or reodering queue is not empty while closing socket

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Message-ID: <4E1733CF.5090004@hp.com>
Date:	Fri, 08 Jul 2011 12:43:59 -0400
From:	Vladislav Yasevich <vladislav.yasevich@...com>
To:	netdev@...r.kernel.org, davem@...emloft.net,
	Wei Yongjun <yjwei@...fujitsu.com>,
	Sridhar Samudrala <sri@...ibm.com>, linux-sctp@...r.kernel.org
Subject: Re: [PATCHv3] sctp: ABORT if receive, reassmbly, or reodering queue
 is not empty while closing socket

On 07/08/2011 10:37 AM, Thomas Graf wrote:
> Trigger user ABORT if application closes a socket which has data
> queued on the socket receive queue or chunks waiting on the
> reassembly or ordering queue as this would imply data being lost
> which defeats the point of a graceful shutdown.
> 
> This behavior is already practiced in TCP.
> 
> We do not check the input queue because that would mean to parse
> all chunks on it to look for unacknowledged data which seems too
> much of an effort. Control chunks or duplicated chunks may also
> be in the input queue and should not be stopping a graceful
> shutdown.
> 
> Signed-off-by: Thomas Graf <tgraf@...radead.org>

Acked-by: Vlad Yasevich <vladislav.yasevich@...com>

-vlad

> 
> diff --git a/include/net/sctp/ulpevent.h b/include/net/sctp/ulpevent.h
> index 99b027b..ca4693b 100644
> --- a/include/net/sctp/ulpevent.h
> +++ b/include/net/sctp/ulpevent.h
> @@ -80,7 +80,7 @@ static inline struct sctp_ulpevent *sctp_skb2event(struct sk_buff *skb)
>  
>  void sctp_ulpevent_free(struct sctp_ulpevent *);
>  int sctp_ulpevent_is_notification(const struct sctp_ulpevent *);
> -void sctp_queue_purge_ulpevents(struct sk_buff_head *list);
> +unsigned int sctp_queue_purge_ulpevents(struct sk_buff_head *list);
>  
>  struct sctp_ulpevent *sctp_ulpevent_make_assoc_change(
>  	const struct sctp_association *asoc,
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 08c6238..d3ccf79 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -1384,6 +1384,7 @@ SCTP_STATIC void sctp_close(struct sock *sk, long timeout)
>  	struct sctp_endpoint *ep;
>  	struct sctp_association *asoc;
>  	struct list_head *pos, *temp;
> +	unsigned int data_was_unread;
>  
>  	SCTP_DEBUG_PRINTK("sctp_close(sk: 0x%p, timeout:%ld)\n", sk, timeout);
>  
> @@ -1393,6 +1394,10 @@ SCTP_STATIC void sctp_close(struct sock *sk, long timeout)
>  
>  	ep = sctp_sk(sk)->ep;
>  
> +	/* Clean up any skbs sitting on the receive queue.  */
> +	data_was_unread = sctp_queue_purge_ulpevents(&sk->sk_receive_queue);
> +	data_was_unread += sctp_queue_purge_ulpevents(&sctp_sk(sk)->pd_lobby);
> +
>  	/* Walk all associations on an endpoint.  */
>  	list_for_each_safe(pos, temp, &ep->asocs) {
>  		asoc = list_entry(pos, struct sctp_association, asocs);
> @@ -1410,7 +1415,9 @@ SCTP_STATIC void sctp_close(struct sock *sk, long timeout)
>  			}
>  		}
>  
> -		if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
> +		if (data_was_unread || !skb_queue_empty(&asoc->ulpq.lobby) ||
> +		    !skb_queue_empty(&asoc->ulpq.reasm) ||
> +		    (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime)) {
>  			struct sctp_chunk *chunk;
>  
>  			chunk = sctp_make_abort_user(asoc, NULL, 0);
> @@ -1420,10 +1427,6 @@ SCTP_STATIC void sctp_close(struct sock *sk, long timeout)
>  			sctp_primitive_SHUTDOWN(asoc, NULL);
>  	}
>  
> -	/* Clean up any skbs sitting on the receive queue.  */
> -	sctp_queue_purge_ulpevents(&sk->sk_receive_queue);
> -	sctp_queue_purge_ulpevents(&sctp_sk(sk)->pd_lobby);
> -
>  	/* On a TCP-style socket, block for at most linger_time if set. */
>  	if (sctp_style(sk, TCP) && timeout)
>  		sctp_wait_for_close(sk, timeout);
> diff --git a/net/sctp/ulpevent.c b/net/sctp/ulpevent.c
> index e70e5fc..8a84017 100644
> --- a/net/sctp/ulpevent.c
> +++ b/net/sctp/ulpevent.c
> @@ -1081,9 +1081,19 @@ void sctp_ulpevent_free(struct sctp_ulpevent *event)
>  }
>  
>  /* Purge the skb lists holding ulpevents. */
> -void sctp_queue_purge_ulpevents(struct sk_buff_head *list)
> +unsigned int sctp_queue_purge_ulpevents(struct sk_buff_head *list)
>  {
>  	struct sk_buff *skb;
> -	while ((skb = skb_dequeue(list)) != NULL)
> -		sctp_ulpevent_free(sctp_skb2event(skb));
> +	unsigned int data_unread = 0;
> +
> +	while ((skb = skb_dequeue(list)) != NULL) {
> +		struct sctp_ulpevent *event = sctp_skb2event(skb);
> +
> +		if (!sctp_ulpevent_is_notification(event))
> +			data_unread += skb->len;
> +
> +		sctp_ulpevent_free(event);
> +	}
> +
> +	return data_unread;
>  }
> 

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