sch_qfq: keep backlog updated with qlen

Reported-by: Stas Nichiporovich <stasn77@gmail.com>
Fixes: 2ccccf5fb43f ("net_sched: update hierarchical backlog too")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_qfq.c

@@ -1153,6 +1153,7 @@ static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
 	if (!skb)
 		return NULL;
 
+	qdisc_qstats_backlog_dec(sch, skb);
 	sch->q.qlen--;
 	qdisc_bstats_update(sch, skb);
 
@@ -1256,6 +1257,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 	}
 
 	bstats_update(&cl->bstats, skb);
+	qdisc_qstats_backlog_inc(sch, skb);
 	++sch->q.qlen;
 
 	agg = cl->agg;
@@ -1476,6 +1478,7 @@ static void qfq_reset_qdisc(struct Qdisc *sch)
 			qdisc_reset(cl->qdisc);
 		}
 	}
+	sch->qstats.backlog = 0;
 	sch->q.qlen = 0;
 }