This fix has been proposed originally by Vlad Yasevich. He says:
When SCTP makes forward progress (receives a SACK that acks new chunks,
renegs, or answeres 0-window probes) or when HB-ACK arrives, mark
the route as confirmed so we don't unnecessarily send NUD probes.
Having a simple SCTP client/server that exchange data chunks every 1sec,
without this patch ARP requests are sent periodically every 40-60sec.
With this fix applied, an ARP request is only done once right at the
"session" beginning. Also, when clearing the related ARP cache entry
manually during the session, a new request is correctly done. I have
only "backported" this to net-next and tested that it works, so full
credit goes to Vlad.
Signed-off-by: Vlad Yasevich <vyasevich@xxxxxxxxx>
Signed-off-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
---
Applies to net-next.
net/sctp/outqueue.c | 9 +++++++++
net/sctp/sm_sideeffect.c | 6 ++++++
2 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index cb80a8e..ef9e2bb 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -1334,6 +1334,7 @@ static void sctp_check_transmitted(struct sctp_outq *q,
__u8 restart_timer = 0;
int bytes_acked = 0;
int migrate_bytes = 0;
+ bool forward_progress = false;
sack_ctsn = ntohl(sack->cum_tsn_ack);
@@ -1400,6 +1401,7 @@ static void sctp_check_transmitted(struct sctp_outq *q,
bytes_acked += sctp_data_size(tchunk);
if (!tchunk->transport)
migrate_bytes += sctp_data_size(tchunk);
+ forward_progress = true;
}
if (TSN_lte(tsn, sack_ctsn)) {
@@ -1413,6 +1415,7 @@ static void sctp_check_transmitted(struct sctp_outq *q,
* current RTO.
*/
restart_timer = 1;
+ forward_progress = true;
if (!tchunk->tsn_gap_acked) {
/*
@@ -1503,6 +1506,7 @@ static void sctp_check_transmitted(struct sctp_outq *q,
*/
transport->error_count = 0;
transport->asoc->overall_error_count = 0;
+ forward_progress = true;
/*
* While in SHUTDOWN PENDING, we may have started
@@ -1576,6 +1580,11 @@ static void sctp_check_transmitted(struct sctp_outq *q,
jiffies + transport->rto))
sctp_transport_hold(transport);
}
+
+ if (forward_progress) {
+ if (transport->dst)
+ dst_confirm(transport->dst);
+ }
}
list_splice(&tlist, transmitted_queue);
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index cf6f845..9da6885 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -730,6 +730,12 @@ static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
SCTP_HEARTBEAT_SUCCESS);
+ /* HB-ACK was received for a the proper HB. Consider this
+ * forward progress.
+ */
+ if (t->dst)
+ dst_confirm(t->dst);
+
/* The receiver of the HEARTBEAT ACK should also perform an
* RTT measurement for that destination transport address
* using the time value carried in the HEARTBEAT ACK chunk.
--
1.7.1
--
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