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    SubjectRe: [PATCH] net: sctp: set chunk->tsn_gap_acked at the end of cycle

    On 11/22/2013 03:27 PM, Vlad Yasevich wrote:
    > On 11/22/2013 02:49 AM, Chang Xiangzhong wrote:
    >> tsn_gap_acked is an important state flag in chunk, which indicates if the
    >> chunk has been acked in gap reports before.
    > Actually, this bit indicates simply that the chunk has been acked. It
    > doesn't state whether it's been acked in a gap report or via cumulative tsn.
    Thanks for pointing this out. Sorry for not having made that clear.
    >
    >> SFR-CACC algorithm depends on this
    >> variable. So set this at the end of each iteration, otherwise the SFR-CACC
    >> algorithm would never be toggled.
    >>
    >> Signed-off-by: Chang Xiangzhong <changxiangzhong@gmail.com>
    >> ---
    >> net/sctp/outqueue.c | 3 ++-
    >> 1 file changed, 2 insertions(+), 1 deletion(-)
    >>
    >> diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
    >> index 1b494fa..bff828c 100644
    >> --- a/net/sctp/outqueue.c
    >> +++ b/net/sctp/outqueue.c
    >> @@ -1396,7 +1396,6 @@ static void sctp_check_transmitted(struct sctp_outq *q,
    >> * while DATA was outstanding).
    >> */
    >> if (!tchunk->tsn_gap_acked) {
    >> - tchunk->tsn_gap_acked = 1;
    >> if (TSN_lt(*highest_new_tsn_in_sack, tsn))
    >> *highest_new_tsn_in_sack = tsn;
    >> bytes_acked += sctp_data_size(tchunk);
    >> @@ -1460,6 +1459,8 @@ static void sctp_check_transmitted(struct sctp_outq *q,
    >> */
    >> list_add_tail(lchunk, &tlist);
    >> }
    >> +
    >> + tchunk->tsn_gap_acked = 1;
    > The current code will set the state if it hasn't been set yet. Why is
    > this needed?
    Because in line 1420 ~ 1440 The SFR-CACC algorithms use tsn_gap_acked.
    That "if block" would never be triggered because the varaiable's been
    set. That's why I move the "state changing sentence" to the end of the
    iteration.
    > Now there is an issue with tracking highest_new_tsn_in_sack. The spec
    > is a little vague on this, but the highest_new_tsn_in_sack only supposed
    > to track tsns that have not been resent. If a tsn has been reneged, and
    > then sent again, it is not considered 'new' thus should not count
    > toward highest_new_tsn_in_sack. We currently do not track this right.
    I'll try to figure this out.
    > -vlad
    >
    > -vlad
    >
    >> } else {
    >> if (tchunk->tsn_gap_acked) {
    >> pr_debug("%s: receiver reneged on data TSN:0x%x\n",
    >>



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