pkt_sched: sch_qfq: do not allow virtual time to jump if an aggregate is in service

By definition of (the algorithm of) QFQ+, the system virtual time must
be pushed up only if there is no 'eligible' aggregate, i.e. no
aggregate that would have started to be served also in the ideal
system emulated by QFQ+.  QFQ+ serves only eligible aggregates, hence
the aggregate currently in service is eligible.  As a consequence, to
decide whether there is no eligible aggregate, QFQ+ must also check
whether there is no aggregate in service.

Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Reviewed-by: Fabio Checconi <fchecconi@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index c34af93ddfe2816a0b47f42a3c592b452c185205..6b7ce803d07c4b79581eeea2cf0d825ee056c57e 100644 (file)
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c
@@ -1279,7 +1279,8 @@ static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
                /* group was surely ineligible, remove */
                __clear_bit(grp->index, &q->bitmaps[IR]);
                __clear_bit(grp->index, &q->bitmaps[IB]);
-       } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V))
+       } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V) &&
+                  q->in_serv_agg == NULL)
                q->V = roundedS;
 
        grp->S = roundedS;