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Date: Tue, 15 Oct 2013 22:13:06 -0400
From: Vlad Yasevich <vyasevich@...il.com>
To: Chang Xiangzhong <changxiangzhong@...il.com>
CC: nhorman@...driver.com, davem@...emloft.net,
linux-sctp@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: 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.
On 10/15/2013 02:13 PM, Chang Xiangzhong wrote:
> Signed-off-by: Xiangzhong Chang <changxiangzhong@...il.com>
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
> ---
> 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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