[PATCH net v2] sctp: donot reset the overall_error_count in SHUTDOWN_RECEIVE state

commit f8d960524 fix the 0 peer.rwnd issue in SHUTDOWN_PENDING state through
not reseting the overall_error_count when receive a heartbeat, but the same
issue also exists in SHUTDOWN_RECEIVE state.

so we change the condition to state < SCTP_STATE_SHUTDOWN_PENDING to reset the
overall_error_count when receive a heartbeat, which can avoid the issue happen
in SCTP_STATE_SHUTDOWN_RECEIVE.

as to SCTP_STATE_SHUTDOWN_ACK_SENT and SCTP_STATE_SHUTDOWN_SENT state, with
this patch, it will not be affected by the heartbeat, cause these two states
have been taken charge of by t2 timer.

Fixes: f8d960524 ("sctp: Enforce retransmission limit during shutdown")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/sctp/sm_sideeffect.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index fef2acd..85e6f03 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c

@@ -702,7 +702,7 @@ static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
 	 * outstanding data and rely on the retransmission limit be reached
 	 * to shutdown the association.
 	 */
-	if (t->asoc->state != SCTP_STATE_SHUTDOWN_PENDING)
+	if (t->asoc->state < SCTP_STATE_SHUTDOWN_PENDING)
 		t->asoc->overall_error_count = 0;
 
 	/* Clear the hb_sent flag to signal that we had a good

-- 
2.1.0

From: Xin Long <lucien.xin@gmail.com>
Date: Sun, 23 Aug 2015 19:30:15 +0800

Vlad et al., please review.

On 08/23/2015 07:30 AM, Xin Long wrote:

commit f8d960524 fix the 0 peer.rwnd issue in SHUTDOWN_PENDING state through
not reseting the overall_error_count when receive a heartbeat, but the same
issue also exists in SHUTDOWN_RECEIVE state.

so we change the condition to state < SCTP_STATE_SHUTDOWN_PENDING to reset the
overall_error_count when receive a heartbeat, which can avoid the issue happen
in SCTP_STATE_SHUTDOWN_RECEIVE.

as to SCTP_STATE_SHUTDOWN_ACK_SENT and SCTP_STATE_SHUTDOWN_SENT state, with
this patch, it will not be affected by the heartbeat, cause these two states
have been taken charge of by t2 timer.

Fixes: f8d960524 ("sctp: Enforce retransmission limit during shutdown")
Signed-off-by: Xin Long <lucien.xin@gmail.com>

The code is OK, but the change log could use some help.

How is this for the explanation:

Commit f8d960524 ("sctp: Enforce retransmission limit during shutdown") fixed a
problem with excessive retransmissions in the SHUTDOWN_PENDING by not resetting
the association overall_error_count.  This allowed the association to better
enforce assoc.max_retrans limit.

However, the same issue still exists when the association is in SHUTDOWN_RECEIVED
state.  In this state, HB-ACKs will continue to reset the overall_error_count
for the association would extend the lifetime of association unnecessarily.

This patch solves this by resetting the overall_error_count whenever the current
state is small then SCTP_STATE_SHUTDOWN_PENDING.  As a small side-effect, we
end up also handling SCTP_STATE_SHUTDOWN_ACK_SENT and SCTP_STATE_SHUTDOWN_SENT
states, but they are not really impacted because we disable Heartbeats in those
states.


Thanks
-vlad