netdev - Re: [PATCH net] sctp: allow delivering notifications after receiving SHUTDOWN

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Message-Id: <20160730.220703.417829793602387422.davem@davemloft.net>
Date:	Sat, 30 Jul 2016 22:07:03 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	lucien.xin@...il.com
Cc:	netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
	marcelo.leitner@...il.com, vyasevich@...il.com,
	daniel@...earbox.net
Subject: Re: [PATCH net] sctp: allow delivering notifications after
 receiving SHUTDOWN

From: Xin Long <lucien.xin@...il.com>
Date: Sat, 30 Jul 2016 14:09:09 +0800

> Prior to this patch, once sctp received SHUTDOWN or shutdown with RD,
> sk->sk_shutdown would be set with RCV_SHUTDOWN, and all events would
> be dropped in sctp_ulpq_tail_event(). It would cause:
> 
> 1. some notifications couldn't be received by users. like
>    SCTP_SHUTDOWN_COMP generated by sctp_sf_do_4_C().
> 
> 2. sctp would also never trigger sk_data_ready when the association
>    was closed, making it harder to identify the end of the association
>    by calling recvmsg() and getting an EOF. It was not convenient for
>    kernel users.
> 
> The check here should be stopping delivering DATA chunks after receiving
> SHUTDOWN, and stopping delivering ANY chunks after sctp_close().
> 
> So this patch is to allow notifications to enqueue into receive queue
> even if sk->sk_shutdown is set to RCV_SHUTDOWN in sctp_ulpq_tail_event,
> but if sk->sk_shutdown == RCV_SHUTDOWN | SEND_SHUTDOWN, it drops all
> events.
> 
> Signed-off-by: Xin Long <lucien.xin@...il.com>

Applied.