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.

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 
> ---
>  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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[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 
---
 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