diff options
| author | Vlad Yasevich <vladislav.yasevich@hp.com> | 2009-02-13 08:33:43 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-02-16 00:03:10 -0800 |
| commit | faee47cdbfe8d74a1573c2f81ea6dbb08d735be6 (patch) | |
| tree | 6a95e8f91087cd3d584fc89f9bc06355d371d82a /net/sctp/sm_sideeffect.c | |
| parent | 4458f04c02a46c679a90ef71f866a415c192deb4 (diff) | |
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>
Diffstat (limited to 'net/sctp/sm_sideeffect.c')
| -rw-r--r-- | net/sctp/sm_sideeffect.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c index e1d6076b4f5..0146cfb1f18 100644 --- a/net/sctp/sm_sideeffect.c +++ b/net/sctp/sm_sideeffect.c @@ -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. */ |