[PATCH V2] For for each TSN t being newly acked (Not only cumulatively, but also SELECTIVELY) cacc_saw_newack should be set to 1.

Subsystems: networking [general], sctp protocol, the rest

STALE4673d

2 messages, 2 authors, 2013-10-16 · open the first message on its own page

[PATCH V2] For for each TSN t being newly acked (Not only cumulatively, but also SELECTIVELY) cacc_saw_newack should be set to 1.

From: Chang Xiangzhong <hidden>
Date: 2013-10-15 18:13:36

Signed-off-by: Xiangzhong Chang <redacted>
---
 net/sctp/outqueue.c |   76 ++++++++++++++++++++++++---------------------------
 1 file changed, 35 insertions(+), 41 deletions(-)
diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index 94df758..84ef3b8 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -1357,13 +1357,13 @@ static void sctp_check_transmitted(struct sctp_outq *q,
 
 		tsn = ntohl(tchunk->subh.data_hdr->tsn);
 		if (sctp_acked(sack, tsn)) {
-			/* If this queue is the retransmit queue, the
-			 * retransmit timer has already reclaimed
-			 * the outstanding bytes for this chunk, so only
-			 * count bytes associated with a transport.
-			 */
-			if (transport) {
-				/* If this chunk is being used for RTT
+			if (!tchunk->tsn_gap_acked) {
+				/* If this queue is the retransmit queue, the
+				 * retransmit timer has already reclaimed
+				 * the outstanding bytes for this chunk, so only
+				 * count bytes associated with a transport.
+				 *
+				 * If this chunk is being used for RTT
 				 * measurement, calculate the RTT and update
 				 * the RTO using this value.
 				 *
@@ -1374,28 +1374,44 @@ static void sctp_check_transmitted(struct sctp_outq *q,
 				 * first instance of the packet or a later
 				 * instance).
 				 */
-				if (!tchunk->tsn_gap_acked &&
-				    tchunk->rtt_in_progress) {
+				if (transport && tchunk->rtt_in_progress) {
 					tchunk->rtt_in_progress = 0;
 					rtt = jiffies - tchunk->sent_at;
 					sctp_transport_update_rto(transport,
-								  rtt);
+						rtt);
 				}
-			}
 
-			/* If the chunk hasn't been marked as ACKED,
-			 * mark it and account bytes_acked if the
-			 * chunk had a valid transport (it will not
-			 * have a transport if ASCONF had deleted it
-			 * while DATA was outstanding).
-			 */
-			if (!tchunk->tsn_gap_acked) {
+				/* If the chunk hasn't been marked as ACKED,
+				 * mark it and account bytes_acked if the
+				 * chunk had a valid transport (it will not
+				 * have a transport if ASCONF had deleted it
+				 * while DATA was outstanding).
+				 */
 				tchunk->tsn_gap_acked = 1;
 				*highest_new_tsn_in_sack = tsn;
 				bytes_acked += sctp_data_size(tchunk);
 				if (!tchunk->transport)
 					migrate_bytes += sctp_data_size(tchunk);
 				forward_progress = true;
+
+				/* 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;
 			}
 
 			if (TSN_lte(tsn, sack_ctsn)) {
@@ -1411,30 +1427,8 @@ 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);
+					&q->sacked);
 			} else {
 				/* RFC2960 7.2.4, sctpimpguide-05 2.8.2
 				 * M2) Each time a SACK arrives reporting
-- 
1.7.9.5

Re: [PATCH V2] For for each TSN t being newly acked (Not only cumulatively, but also SELECTIVELY) cacc_saw_newack should be set to 1.

From: Vlad Yasevich <hidden>
Date: 2013-10-16 02:13:15

On 10/15/2013 02:13 PM, Chang Xiangzhong wrote:
Signed-off-by: Xiangzhong Chang <redacted>
Your proposed solution is very nice, but it does 2 things in one
patch.
  1) It fixes the bug
  2) It refactors the code to improve the flow.

While (2) is very nice, it needs a much more careful review.
Can you please split this into 2 patches?  First patch can
make the code look like this:

	if (sctp_acked(sack, tsn)) {
		...
		if (!tchunk->tsn_gap_acked) {
			tchunk->tsn_gap_acked = 1;
			*highest_new_tsn_in_sack = tsn;
			bytes_acked += sctp_data_size(tchunk);
                         if (!tchunk->transport)
				migrate_bytes += sctp_data_size(tchunk);
			forward_progress = true;

			/*
			 * 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:
			...
		}
	}

Then you can file a second patch to improve the flow/refactor the 
function.  You have to be very careful here though and be sure to
run through all the regression tests since you would be modifying
a very critcal part of the code.

Thanks
-vlad
quoted hunk
---
  net/sctp/outqueue.c |   76 ++++++++++++++++++++++++---------------------------
  1 file changed, 35 insertions(+), 41 deletions(-)
diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index 94df758..84ef3b8 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -1357,13 +1357,13 @@ static void sctp_check_transmitted(struct sctp_outq *q,

  		tsn = ntohl(tchunk->subh.data_hdr->tsn);
  		if (sctp_acked(sack, tsn)) {
-			/* If this queue is the retransmit queue, the
-			 * retransmit timer has already reclaimed
-			 * the outstanding bytes for this chunk, so only
-			 * count bytes associated with a transport.
-			 */
-			if (transport) {
-				/* If this chunk is being used for RTT
+			if (!tchunk->tsn_gap_acked) {
+				/* If this queue is the retransmit queue, the
+				 * retransmit timer has already reclaimed
+				 * the outstanding bytes for this chunk, so only
+				 * count bytes associated with a transport.
+				 *
+				 * If this chunk is being used for RTT
  				 * measurement, calculate the RTT and update
  				 * the RTO using this value.
  				 *
@@ -1374,28 +1374,44 @@ static void sctp_check_transmitted(struct sctp_outq *q,
  				 * first instance of the packet or a later
  				 * instance).
  				 */
-				if (!tchunk->tsn_gap_acked &&
-				    tchunk->rtt_in_progress) {
+				if (transport && tchunk->rtt_in_progress) {
  					tchunk->rtt_in_progress = 0;
  					rtt = jiffies - tchunk->sent_at;
  					sctp_transport_update_rto(transport,
-								  rtt);
+						rtt);
  				}
-			}

-			/* If the chunk hasn't been marked as ACKED,
-			 * mark it and account bytes_acked if the
-			 * chunk had a valid transport (it will not
-			 * have a transport if ASCONF had deleted it
-			 * while DATA was outstanding).
-			 */
-			if (!tchunk->tsn_gap_acked) {
+				/* If the chunk hasn't been marked as ACKED,
+				 * mark it and account bytes_acked if the
+				 * chunk had a valid transport (it will not
+				 * have a transport if ASCONF had deleted it
+				 * while DATA was outstanding).
+				 */
  				tchunk->tsn_gap_acked = 1;
  				*highest_new_tsn_in_sack = tsn;
  				bytes_acked += sctp_data_size(tchunk);
  				if (!tchunk->transport)
  					migrate_bytes += sctp_data_size(tchunk);
  				forward_progress = true;
+
+				/* 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;
  			}

  			if (TSN_lte(tsn, sack_ctsn)) {
@@ -1411,30 +1427,8 @@ 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);
+					&q->sacked);
  			} else {
  				/* RFC2960 7.2.4, sctpimpguide-05 2.8.2
  				 * M2) Each time a SACK arrives reporting
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