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sctp: Fix the RTO-doubling on idle-link heartbeats 

SCTP incorrectly doubles rto ever time a Hearbeat chunk
is generated.   However RFC 4960 states:

   On an idle destination address that is allowed to heartbeat, it is
   recommended that a HEARTBEAT chunk is sent once per RTO of that
   destination address plus the protocol parameter 'HB.interval', with
   jittering of +/- 50% of the RTO value, and exponential backoff of the
   RTO if the previous HEARTBEAT is unanswered.

Essentially, of if the heartbean is unacknowledged, do we double the RTO.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vlad Yasevich 2009-02-13 08:33:43 +00:00 committed by David S. Miller
parent 4458f04c02
commit faee47cdbf
3 changed files with 19 additions and 2 deletions
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2
include/net/sctp/structs.h
View File

@ -910,8 +910,10 @@ struct sctp_transport {
* should be set. Every time the RTT
* calculation completes (i.e. the DATA chunk
* is SACK'd) clear this flag.
* hb_sent : a flag that signals that we have a pending heartbeat.
*/
__u8 rto_pending;
__u8 hb_sent;
/* Flag to track the current fast recovery state */
__u8 fast_recovery;

17
net/sctp/sm_sideeffect.c
View File

@ -461,9 +461,15 @@ static void sctp_do_8_2_transport_strike(struct sctp_association *asoc,
* expires, set RTO <- RTO * 2 ("back off the timer"). The
* maximum value discussed in rule C7 above (RTO.max) may be
* used to provide an upper bound to this doubling operation.
*
* Special Case: the first HB doesn't trigger exponential backoff.
* The first unacknowleged HB triggers it. We do this with a flag
* that indicates that we have an outstanding HB.
*/
transport->last_rto = transport->rto;
transport->rto = min((transport->rto * 2), transport->asoc->rto_max);
if (transport->hb_sent) {
transport->last_rto = transport->rto;
transport->rto = min((transport->rto * 2), transport->asoc->rto_max);
}
}
/* Worker routine to handle INIT command failure. */
@ -621,6 +627,11 @@ static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
t->error_count = 0;
t->asoc->overall_error_count = 0;
/* Clear the hb_sent flag to signal that we had a good
* acknowledgement.
*/
t->hb_sent = 0;
/* Mark the destination transport address as active if it is not so
* marked.
*/
@ -657,6 +668,8 @@ static void sctp_cmd_transport_reset(sctp_cmd_seq_t *cmds,
/* Mark one strike against a transport. */
sctp_do_8_2_transport_strike(asoc, t);
t->hb_sent = 1;
}
/* Helper function to process the process SACK command. */

2
net/sctp/transport.c
View File

@ -79,6 +79,7 @@ static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer,
peer->rttvar = 0;
peer->srtt = 0;
peer->rto_pending = 0;
peer->hb_sent = 0;
peer->fast_recovery = 0;
peer->last_time_heard = jiffies;
@ -608,6 +609,7 @@ void sctp_transport_reset(struct sctp_transport *t)
t->flight_size = 0;
t->error_count = 0;
t->rto_pending = 0;
t->hb_sent = 0;
t->fast_recovery = 0;
/* Initialize the state information for SFR-CACC */