[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, 3 insertions, 0 deletions

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index d0d6e595a78c..459cda258a5c 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -393,6 +393,7 @@ static int sfq_change(struct Qdisc *sch, struct rtattr *opt)
 {
         struct sfq_sched_data *q = qdisc_priv(sch);
         struct tc_sfq_qopt *ctl = RTA_DATA(opt);
+        unsigned int qlen;
 
         if (opt->rta_len < RTA_LENGTH(sizeof(*ctl)))
                 return -EINVAL;
@@ -403,8 +404,10 @@ static int sfq_change(struct Qdisc *sch, struct rtattr *opt)
         if (ctl->limit)
                 q->limit = min_t(u32, ctl->limit, SFQ_DEPTH);
 
+        qlen = sch->q.qlen;
         while (sch->q.qlen >= q->limit-1)
                 sfq_drop(sch);
+        qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen);
 
         del_timer(&q->perturb_timer);
         if (q->perturb_period) {