[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 ee66c5ca80c6..acddad08850f 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;
 }