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

[Chang]

On 11/22/2013 11:48 PM, Vlad Yasevich wrote:
> On 11/22/2013 02:24 PM, Chang wrote:
> > 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@xxxxxxxxx>
> > > > ---
> > > >    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.
> So the solution that's been proposed before is to move the CACC block up
> and merge it with the !tsn_gap_acked block.  This requires additional
> change though to only mark highest_new_tsn if the chunk has not been
> retransmitted (which you've added in a prior patch).
>
> -vlad
Yeah, I've mixed that up with a prior patch. How was the previous patch? 
Was it approved?
-chang
> > > -vlad
> > >
> > > -vlad
> > >
> > > >            } else {
> > > >                if (tchunk->tsn_gap_acked) {
> > > >                    pr_debug("%s: receiver reneged on data TSN:0x%x\n",

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