[NET_SCHED]: Fix endless loops (part 2): "simple" qdiscs

Convert the "simple" qdiscs to use qdisc_tree_decrease_qlen() where
necessary:

- all graft operations
- destruction of old child qdiscs in prio, red and tbf change operation
- purging of queue in sfq change operation

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index ee66c5ca80c..acddad08850 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -229,8 +229,10 @@ static int red_change(struct Qdisc *sch, struct rtattr *opt)
 	sch_tree_lock(sch);
 	q->flags = ctl->flags;
 	q->limit = ctl->limit;
-	if (child)
+	if (child) {
+		qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
 		qdisc_destroy(xchg(&q->qdisc, child));
+	}
 
 	red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
 				 ctl->Plog, ctl->Scell_log,
@@ -308,8 +310,8 @@ static int red_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
 
 	sch_tree_lock(sch);
 	*old = xchg(&q->qdisc, new);
+	qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
 	qdisc_reset(*old);
-	sch->q.qlen = 0;
 	sch_tree_unlock(sch);
 	return 0;
 }