[PATCH net 0/5] sctp: some fixes of prsctp polices

[PATCH net 0/5] sctp: some fixes of prsctp polices

[Xin Long]

This patchset is to improve some codes about prsctp polices, and also
to fix some issues.

Xin Long (5):
  sctp: move sent_count to the memory hole in sctp_chunk
  sctp: reuse sent_count to avoid retransmitted chunks for RTT
    measurements
  sctp: remove prsctp_param from sctp_chunk
  sctp: change to check peer prsctp_capable when using prsctp polices
  sctp: remove the old ttl expires policy

 include/net/sctp/structs.h | 15 +++------------
 net/sctp/chunk.c           | 31 ++++++++++---------------------
 net/sctp/output.c          |  6 ++----
 net/sctp/outqueue.c        | 16 +++++++---------
 net/sctp/sm_make_chunk.c   | 15 ---------------
 5 files changed, 22 insertions(+), 61 deletions(-)

-- 
2.1.0

[PATCH net 1/5] sctp: move sent_count to the memory hole in sctp_chunk

[Xin Long]

Now pahole sctp_chunk, it has 2 memory holes:
   struct sctp_chunk {
	struct list_head           list;
	atomic_t                   refcnt;
	/* XXX 4 bytes hole, try to pack */
	...
	long unsigned int          prsctp_param;
	int                        sent_count;
	/* XXX 4 bytes hole, try to pack */

This patch is to move up sent_count to fill the 1st one and eliminate
the 2nd one.

It's not just another struct compaction, it also fixes the "netperf-
Throughput_Mbps -37.2% regression" issue when overloading the CPU.

Fixes: a6c2f792873a ("sctp: implement prsctp TTL policy")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 include/net/sctp/structs.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index ce93c4b..4f097f5 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -554,6 +554,9 @@ struct sctp_chunk {
 
 	atomic_t refcnt;
 
+	/* How many times this chunk have been sent, for prsctp RTX policy */
+	int sent_count;
+
 	/* This is our link to the per-transport transmitted list.  */
 	struct list_head transmitted_list;
 
@@ -610,9 +613,6 @@ struct sctp_chunk {
 	 */
 	unsigned long prsctp_param;
 
-	/* How many times this chunk have been sent, for prsctp RTX policy */
-	int sent_count;
-
 	/* Which association does this belong to?  */
 	struct sctp_association *asoc;
 
-- 
2.1.0

[PATCH net 2/5] sctp: reuse sent_count to avoid retransmitted chunks for RTT measurements

[Xin Long]

Now sctp uses chunk->resent to record if a chunk is retransmitted, for
RTT measurements with retransmitted DATA chunks. chunk->sent_count was
introduced to record how many times one chunk has been sent for prsctp
RTX policy before. We actually can know if one chunk is retransmitted
by checking chunk->sent_count is greater than 1.

This patch is to remove resent from sctp_chunk and reuse sent_count
to avoid retransmitted chunks for RTT measurements.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 include/net/sctp/structs.h | 1 -
 net/sctp/output.c          | 3 ++-
 net/sctp/outqueue.c        | 4 +---
 3 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 4f097f5..81a5faa 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -647,7 +647,6 @@ struct sctp_chunk {
 #define SCTP_NEED_FRTX 0x1
 #define SCTP_DONT_FRTX 0x2
 	__u16	rtt_in_progress:1,	/* This chunk used for RTT calc? */
-		resent:1,		/* Has this chunk ever been resent. */
 		has_tsn:1,		/* Does this chunk have a TSN yet? */
 		has_ssn:1,		/* Does this chunk have a SSN yet? */
 		singleton:1,		/* Only chunk in the packet? */
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 31b7bc3..483d2ed 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -547,7 +547,8 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 				 * for a given destination transport address.
 				 */
 
-				if (!chunk->resent && !tp->rto_pending) {
+				if (chunk->sent_count == 1 &&
+				    !tp->rto_pending) {
 					chunk->rtt_in_progress = 1;
 					tp->rto_pending = 1;
 				}
diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index 72e54a4..2a629fa 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -536,8 +536,6 @@ void sctp_retransmit_mark(struct sctp_outq *q,
 				transport->rto_pending = 0;
 			}
 
-			chunk->resent = 1;
-
 			/* Move the chunk to the retransmit queue. The chunks
 			 * on the retransmit queue are always kept in order.
 			 */
@@ -1467,7 +1465,7 @@ static void sctp_check_transmitted(struct sctp_outq *q,
 				 * instance).
 				 */
 				if (!tchunk->tsn_gap_acked &&
-				    !tchunk->resent &&
+				    tchunk->sent_count == 1 &&
 				    tchunk->rtt_in_progress) {
 					tchunk->rtt_in_progress = 0;
 					rtt = jiffies - tchunk->sent_at;
-- 
2.1.0

[PATCH net 3/5] sctp: remove prsctp_param from sctp_chunk

[Xin Long]

Now sctp uses chunk->prsctp_param to save the prsctp param for all the
prsctp polices, we didn't need to introduce prsctp_param to sctp_chunk.
We can just use chunk->sinfo.sinfo_timetolive for RTX and BUF polices,
and reuse msg->expires_at for TTL policy, as the prsctp polices and old
expires policy are mutual exclusive.

This patch is to remove prsctp_param from sctp_chunk, and reuse msg's
expires_at for TTL and chunk's sinfo.sinfo_timetolive for RTX and BUF
polices.

Note that sctp can't use chunk's sinfo.sinfo_timetolive for TTL policy,
as it needs a u64 variables to save the expires_at time.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 include/net/sctp/structs.h |  7 -------
 net/sctp/chunk.c           |  9 +++++++--
 net/sctp/outqueue.c        |  4 ++--
 net/sctp/sm_make_chunk.c   | 15 ---------------
 4 files changed, 9 insertions(+), 26 deletions(-)

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 81a5faa..ed74ba0 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -606,13 +606,6 @@ struct sctp_chunk {
 	/* This needs to be recoverable for SCTP_SEND_FAILED events. */
 	struct sctp_sndrcvinfo sinfo;
 
-	/* We use this field to record param for prsctp policies,
-	 * for TTL policy, it is the time_to_drop of this chunk,
-	 * for RTX policy, it is the max_sent_count of this chunk,
-	 * for PRIO policy, it is the priority of this chunk.
-	 */
-	unsigned long prsctp_param;
-
 	/* Which association does this belong to?  */
 	struct sctp_association *asoc;
 
diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
index a55e547..14990e2 100644
--- a/net/sctp/chunk.c
+++ b/net/sctp/chunk.c
@@ -179,6 +179,11 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 			 msg, msg->expires_at, jiffies);
 	}
 
+	if (asoc->prsctp_enable &&
+	    SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags))
+		msg->expires_at =
+			jiffies + msecs_to_jiffies(sinfo->sinfo_timetolive);
+
 	/* This is the biggest possible DATA chunk that can fit into
 	 * the packet
 	 */
@@ -349,14 +354,14 @@ int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 	}
 
 	if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
-	    time_after(jiffies, chunk->prsctp_param)) {
+	    time_after(jiffies, chunk->msg->expires_at)) {
 		if (chunk->sent_count)
 			chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
 		else
 			chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
 		return 1;
 	} else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&
-		   chunk->sent_count > chunk->prsctp_param) {
+		   chunk->sent_count > chunk->sinfo.sinfo_timetolive) {
 		chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
 		return 1;
 	}
diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index 2a629fa..df6bb59 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -383,7 +383,7 @@ static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
 
 	list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
 		if (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
-		    chk->prsctp_param <= sinfo->sinfo_timetolive)
+		    chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive)
 			continue;
 
 		list_del_init(&chk->transmitted_list);
@@ -418,7 +418,7 @@ static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
 
 	list_for_each_entry_safe(chk, temp, queue, list) {
 		if (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
-		    chk->prsctp_param <= sinfo->sinfo_timetolive)
+		    chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive)
 			continue;
 
 		list_del_init(&chk->list);
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 8c77b87..46ffecc 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -706,20 +706,6 @@ nodata:
 	return retval;
 }
 
-static void sctp_set_prsctp_policy(struct sctp_chunk *chunk,
-				   const struct sctp_sndrcvinfo *sinfo)
-{
-	if (!chunk->asoc->prsctp_enable)
-		return;
-
-	if (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags))
-		chunk->prsctp_param =
-			jiffies + msecs_to_jiffies(sinfo->sinfo_timetolive);
-	else if (SCTP_PR_RTX_ENABLED(sinfo->sinfo_flags) ||
-		 SCTP_PR_PRIO_ENABLED(sinfo->sinfo_flags))
-		chunk->prsctp_param = sinfo->sinfo_timetolive;
-}
-
 /* Make a DATA chunk for the given association from the provided
  * parameters.  However, do not populate the data payload.
  */
@@ -753,7 +739,6 @@ struct sctp_chunk *sctp_make_datafrag_empty(struct sctp_association *asoc,
 
 	retval->subh.data_hdr = sctp_addto_chunk(retval, sizeof(dp), &dp);
 	memcpy(&retval->sinfo, sinfo, sizeof(struct sctp_sndrcvinfo));
-	sctp_set_prsctp_policy(retval, sinfo);
 
 nodata:
 	return retval;
-- 
2.1.0

[PATCH net 4/5] sctp: change to check peer prsctp_capable when using prsctp polices

[Xin Long]

Now before using prsctp polices, sctp uses asoc->prsctp_enable to
check if prsctp is enabled. However asoc->prsctp_enable is set only
means local host support prsctp, sctp should not abandon packet if
peer host doesn't enable prsctp.

So this patch is to use asoc->peer.prsctp_capable to check if prsctp
is enabled on both side, instead of asoc->prsctp_enable, as asoc's
peer.prsctp_capable is set only when local and peer both enable prsctp.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/sctp/chunk.c    | 4 ++--
 net/sctp/outqueue.c | 8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
index 14990e2..0a3dbec 100644
--- a/net/sctp/chunk.c
+++ b/net/sctp/chunk.c
@@ -179,7 +179,7 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 			 msg, msg->expires_at, jiffies);
 	}
 
-	if (asoc->prsctp_enable &&
+	if (asoc->peer.prsctp_capable &&
 	    SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags))
 		msg->expires_at =
 			jiffies + msecs_to_jiffies(sinfo->sinfo_timetolive);
@@ -340,7 +340,7 @@ errout:
 /* Check whether this message has expired. */
 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 {
-	if (!chunk->asoc->prsctp_enable ||
+	if (!chunk->asoc->peer.prsctp_capable ||
 	    !SCTP_PR_POLICY(chunk->sinfo.sinfo_flags)) {
 		struct sctp_datamsg *msg = chunk->msg;
 
diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index df6bb59..a549363 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -326,7 +326,7 @@ int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
 
 			sctp_chunk_hold(chunk);
 			sctp_outq_tail_data(q, chunk);
-			if (chunk->asoc->prsctp_enable &&
+			if (chunk->asoc->peer.prsctp_capable &&
 			    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
 				chunk->asoc->sent_cnt_removable++;
 			if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
@@ -442,7 +442,7 @@ void sctp_prsctp_prune(struct sctp_association *asoc,
 {
 	struct sctp_transport *transport;
 
-	if (!asoc->prsctp_enable || !asoc->sent_cnt_removable)
+	if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
 		return;
 
 	msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
@@ -1053,7 +1053,7 @@ static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
 
 				/* Mark as failed send. */
 				sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
-				if (asoc->prsctp_enable &&
+				if (asoc->peer.prsctp_capable &&
 				    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
 					asoc->sent_cnt_removable--;
 				sctp_chunk_free(chunk);
@@ -1345,7 +1345,7 @@ int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
 		tsn = ntohl(tchunk->subh.data_hdr->tsn);
 		if (TSN_lte(tsn, ctsn)) {
 			list_del_init(&tchunk->transmitted_list);
-			if (asoc->prsctp_enable &&
+			if (asoc->peer.prsctp_capable &&
 			    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
 				asoc->sent_cnt_removable--;
 			sctp_chunk_free(tchunk);
-- 
2.1.0

[PATCH net 5/5] sctp: remove the old ttl expires policy

[Xin Long]

The prsctp polices include ttl expires policy already, we should remove
the old ttl expires codes, and just adjust the new polices' codes to be
compatible with the old one for users.

This patch is to remove all the old expires codes, and if prsctp polices
are not set, it will still set msg's expires_at and check the expires in
sctp_check_abandoned.

Note that asoc->prsctp_enable is set by default, so users can't feel any
difference even if they use the old expires api in userspace.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 include/net/sctp/structs.h |  1 -
 net/sctp/chunk.c           | 32 ++++++++------------------------
 net/sctp/output.c          |  3 ---
 3 files changed, 8 insertions(+), 28 deletions(-)

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index ed74ba0..a4a18f1 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -530,7 +530,6 @@ struct sctp_datamsg {
 	/* Did the messenge fail to send? */
 	int send_error;
 	u8 send_failed:1,
-	   can_abandon:1,   /* can chunks from this message can be abandoned. */
 	   can_delay;	    /* should this message be Nagle delayed */
 };
 
diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
index 0a3dbec..8d366fc 100644
--- a/net/sctp/chunk.c
+++ b/net/sctp/chunk.c
@@ -52,7 +52,6 @@ static void sctp_datamsg_init(struct sctp_datamsg *msg)
 	atomic_set(&msg->refcnt, 1);
 	msg->send_failed = 0;
 	msg->send_error = 0;
-	msg->can_abandon = 0;
 	msg->can_delay = 1;
 	msg->expires_at = 0;
 	INIT_LIST_HEAD(&msg->chunks);
@@ -169,20 +168,11 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
 	/* Note: Calculate this outside of the loop, so that all fragments
 	 * have the same expiration.
 	 */
-	if (sinfo->sinfo_timetolive) {
-		/* sinfo_timetolive is in milliseconds */
+	if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive &&
+	    (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) ||
+	     !SCTP_PR_POLICY(sinfo->sinfo_flags)))
 		msg->expires_at = jiffies +
 				    msecs_to_jiffies(sinfo->sinfo_timetolive);
-		msg->can_abandon = 1;
-
-		pr_debug("%s: msg:%p expires_at:%ld jiffies:%ld\n", __func__,
-			 msg, msg->expires_at, jiffies);
-	}
-
-	if (asoc->peer.prsctp_capable &&
-	    SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags))
-		msg->expires_at =
-			jiffies + msecs_to_jiffies(sinfo->sinfo_timetolive);
 
 	/* This is the biggest possible DATA chunk that can fit into
 	 * the packet
@@ -340,18 +330,8 @@ errout:
 /* Check whether this message has expired. */
 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 {
-	if (!chunk->asoc->peer.prsctp_capable ||
-	    !SCTP_PR_POLICY(chunk->sinfo.sinfo_flags)) {
-		struct sctp_datamsg *msg = chunk->msg;
-
-		if (!msg->can_abandon)
-			return 0;
-
-		if (time_after(jiffies, msg->expires_at))
-			return 1;
-
+	if (!chunk->asoc->peer.prsctp_capable)
 		return 0;
-	}
 
 	if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
 	    time_after(jiffies, chunk->msg->expires_at)) {
@@ -364,6 +344,10 @@ int sctp_chunk_abandoned(struct sctp_chunk *chunk)
 		   chunk->sent_count > chunk->sinfo.sinfo_timetolive) {
 		chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
 		return 1;
+	} else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) &&
+		   chunk->msg->expires_at &&
+		   time_after(jiffies, chunk->msg->expires_at)) {
+		return 1;
 	}
 	/* PRIO policy is processed by sendmsg, not here */
 
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 483d2ed..e50079d 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -868,9 +868,6 @@ static void sctp_packet_append_data(struct sctp_packet *packet,
 		rwnd = 0;
 
 	asoc->peer.rwnd = rwnd;
-	/* Has been accepted for transmission. */
-	if (!asoc->peer.prsctp_capable)
-		chunk->msg->can_abandon = 0;
 	sctp_chunk_assign_tsn(chunk);
 	sctp_chunk_assign_ssn(chunk);
 }
-- 
2.1.0

Re: [PATCH net 2/5] sctp: reuse sent_count to avoid retransmitted chunks for RTT measurements

[Neil Horman]

On Mon, Sep 26, 2016 at 05:47:51PM +0800, Xin Long wrote:
> Now sctp uses chunk->resent to record if a chunk is retransmitted, for
> RTT measurements with retransmitted DATA chunks. chunk->sent_count was
> introduced to record how many times one chunk has been sent for prsctp
> RTX policy before. We actually can know if one chunk is retransmitted
> by checking chunk->sent_count is greater than 1.
> 
> This patch is to remove resent from sctp_chunk and reuse sent_count
> to avoid retransmitted chunks for RTT measurements.
> 
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
> ---
>  include/net/sctp/structs.h | 1 -
>  net/sctp/output.c          | 3 ++-
>  net/sctp/outqueue.c        | 4 +---
>  3 files changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> index 4f097f5..81a5faa 100644
> --- a/include/net/sctp/structs.h
> +++ b/include/net/sctp/structs.h
> @@ -647,7 +647,6 @@ struct sctp_chunk {
>  #define SCTP_NEED_FRTX 0x1
>  #define SCTP_DONT_FRTX 0x2
>  	__u16	rtt_in_progress:1,	/* This chunk used for RTT calc? */
> -		resent:1,		/* Has this chunk ever been resent. */
>  		has_tsn:1,		/* Does this chunk have a TSN yet? */
>  		has_ssn:1,		/* Does this chunk have a SSN yet? */
>  		singleton:1,		/* Only chunk in the packet? */
> diff --git a/net/sctp/output.c b/net/sctp/output.c
> index 31b7bc3..483d2ed 100644
> --- a/net/sctp/output.c
> +++ b/net/sctp/output.c
> @@ -547,7 +547,8 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
>  				 * for a given destination transport address.
>  				 */
>  
> -				if (!chunk->resent && !tp->rto_pending) {
> +				if (chunk->sent_count == 1 &&
> +				    !tp->rto_pending) {
>  					chunk->rtt_in_progress = 1;
>  					tp->rto_pending = 1;
>  				}
> diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
> index 72e54a4..2a629fa 100644
> --- a/net/sctp/outqueue.c
> +++ b/net/sctp/outqueue.c
> @@ -536,8 +536,6 @@ void sctp_retransmit_mark(struct sctp_outq *q,
>  				transport->rto_pending = 0;
>  			}
>  
> -			chunk->resent = 1;
> -
>  			/* Move the chunk to the retransmit queue. The chunks
>  			 * on the retransmit queue are always kept in order.
>  			 */
> @@ -1467,7 +1465,7 @@ static void sctp_check_transmitted(struct sctp_outq *q,
>  				 * instance).
>  				 */
>  				if (!tchunk->tsn_gap_acked &&
> -				    !tchunk->resent &&
> +				    tchunk->sent_count == 1 &&
>  				    tchunk->rtt_in_progress) {
>  					tchunk->rtt_in_progress = 0;
>  					rtt = jiffies - tchunk->sent_at;
> -- 
> 2.1.0
> 

Maybe wrap this in a macro?  i.e.:
#define chunk_retransmitted(chunk) (chunk->sent_count > 1)

For readability?


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Re: [PATCH net 2/5] sctp: reuse sent_count to avoid retransmitted chunks for RTT measurements

[Xin Long]

>
> Maybe wrap this in a macro?  i.e.:
> #define chunk_retransmitted(chunk) (chunk->sent_count > 1)
>
> For readability?
>
That's a nice suggestion.
chunk->sent_count == 1 is confusing there for reading.
will improve it in v2.

Thanks.