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sctp: allow delivering notifications after receiving SHUTDOWN

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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@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2016-07-30 14:09:09 +08:00 committed by David S. Miller
parent 1aa25ec227
commit a0fc6843f9
1 changed files with 3 additions and 1 deletions
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4
net/sctp/ulpqueue.c
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@ -204,7 +204,9 @@ int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
/* If the socket is just going to throw this away, do not
* even try to deliver it.
*/
if (sock_flag(sk, SOCK_DEAD) || (sk->sk_shutdown & RCV_SHUTDOWN))
if (sk->sk_shutdown & RCV_SHUTDOWN &&
(sk->sk_shutdown & SEND_SHUTDOWN ||
!sctp_ulpevent_is_notification(event)))
goto out_free;
if (!sctp_ulpevent_is_notification(event)) {