[PATCH 3.16 028/366] sctp: fix identification of new acks for SFR-CACC

Ben Hutchings
2018-11-11T20:41:03Z

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

commit 51446780fc33e45cb790c05a7fa2c5bf7e8bc53b upstream.

It's currently written as:

if (!tchunk->tsn_gap_acked) { [1]
tchunk->tsn_gap_acked = 1;
...
}

if (TSN_lte(tsn, sack_ctsn)) {
if (!tchunk->tsn_gap_acked) {
/* SFR-CACC processing */
...
}
}

Which causes the SFR-CACC processing on ack reception to never process,
as tchunk->tsn_gap_acked is always true by then. Block [1] was
moved to that position by the commit marked below.

This patch fixes it by doing SFR-CACC processing earlier, before
tsn_gap_acked is set to true.

Fixes: 31b02e154940 ("sctp: Failover transmitted list on transport delete")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/sctp/outqueue.c | 48 ++++++++++++++++++++++-----------------------
1 file changed, 23 insertions(+), 25 deletions(-)

--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -1346,7 +1346,7 @@ static void sctp_check_transmitted(struc
* the outstanding bytes for this chunk, so only
* count bytes associated with a transport.
*/
- if (transport) {
+ if (transport && !tchunk->tsn_gap_acked) {
/* If this chunk is being used for RTT
* measurement, calculate the RTT and update
* the RTO using this value.
@@ -1358,14 +1358,34 @@ static void sctp_check_transmitted(struc
* first instance of the packet or a later
* instance).
*/
- if (!tchunk->tsn_gap_acked &&
- !tchunk->resent &&
+ if (!tchunk->resent &&
tchunk->rtt_in_progress) {
tchunk->rtt_in_progress = 0;
rtt = jiffies - tchunk->sent_at;
sctp_transport_update_rto(transport,
rtt);
}
+
+ if (TSN_lte(tsn, sack_ctsn)) {
+ /*
+ * SFR-CACC algorithm:
+ * 2) If the SACK contains gap acks
+ * and the flag CHANGEOVER_ACTIVE is
+ * set the receiver of the SACK MUST
+ * take the following action:
+ *
+ * B) For each TSN t being acked that
+ * has not been acked in any SACK so
+ * far, set cacc_saw_newack to 1 for
+ * the destination that the TSN was
+ * sent to.
+ */
+ if (sack->num_gap_ack_blocks &&
+ q->asoc->peer.primary_path->cacc.
+ changeover_active)
+ transport->cacc.cacc_saw_newack
+ = 1;
+ }
}

/* If the chunk hasn't been marked as ACKED,
@@ -1397,28 +1417,6 @@ static void sctp_check_transmitted(struc
restart_timer = 1;
forward_progress = true;

- if (!tchunk->tsn_gap_acked) {
- /*
- * SFR-CACC algorithm:
- * 2) If the SACK contains gap acks
- * and the flag CHANGEOVER_ACTIVE is
- * set the receiver of the SACK MUST
- * take the following action:
- *
- * B) For each TSN t being acked that
- * has not been acked in any SACK so
- * far, set cacc_saw_newack to 1 for
- * the destination that the TSN was
- * sent to.
- */
- if (transport &&
- sack->num_gap_ack_blocks &&
- q->asoc->peer.primary_path->cacc.
- changeover_active)
- transport->cacc.cacc_saw_newack
- = 1;
- }
-
list_add_tail(&tchunk->transmitted_list,
&q->sacked);
} else {