sch_dsmark: update backlog as well

[ Upstream commit bdf17661 ]

Similarly, we need to update backlog too when we update qlen.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: open-code qdisc_qstats_backlog_{inc,dec}()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/sched/sch_dsmark.c

@@ -255,6 +255,7 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 		return err;
 	}
 
+	sch->qstats.backlog += qdisc_pkt_len(skb);
 	sch->q.qlen++;
 
 	return NET_XMIT_SUCCESS;
@@ -277,6 +278,7 @@ static struct sk_buff *dsmark_dequeue(struct Qdisc *sch)
 		return NULL;
 
 	qdisc_bstats_update(sch, skb);
+	sch->qstats.backlog -= qdisc_pkt_len(skb);
 	sch->q.qlen--;
 
 	index = skb->tc_index & (p->indices - 1);
@@ -392,6 +394,7 @@ static void dsmark_reset(struct Qdisc *sch)
 
 	pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
 	qdisc_reset(p->q);
+	sch->qstats.backlog = 0;
 	sch->q.qlen = 0;
 }