sctp: fix identification of new acks for SFR-CACC

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>

1 files changed, 23 insertions, 25 deletions

diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index f211b3db6a35..dee7cbd54831 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -1457,7 +1457,7 @@ static void sctp_check_transmitted(struct sctp_outq *q,
                          * 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.
@@ -1469,14 +1469,34 @@ static void sctp_check_transmitted(struct sctp_outq *q,
                                  * first instance of the packet or a later
                                  * instance).
                                  */
-                                if (!tchunk->tsn_gap_acked &&
-                                    !sctp_chunk_retransmitted(tchunk) &&
+                                if (!sctp_chunk_retransmitted(tchunk) &&
                                     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,
@@ -1508,28 +1528,6 @@ static void sctp_check_transmitted(struct sctp_outq *q,
                                 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 {