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authorVlad Yasevich <vladislav.yasevich@hp.com>2009-02-13 08:33:43 +0000
committerDavid S. Miller <davem@davemloft.net>2009-02-16 00:03:10 -0800
commitfaee47cdbfe8d74a1573c2f81ea6dbb08d735be6 (patch)
tree6a95e8f91087cd3d584fc89f9bc06355d371d82a
parent4458f04c02a46c679a90ef71f866a415c192deb4 (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>
-rw-r--r--include/net/sctp/structs.h2
-rw-r--r--net/sctp/sm_sideeffect.c17
-rw-r--r--net/sctp/transport.c2
3 files changed, 19 insertions, 2 deletions
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 9f70d54fcefc..23f08fe1d50a 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -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;
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index e1d6076b4f59..0146cfb1f182 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. */
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index e745c118f239..5c29b14ee9af 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -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 */