sch_red: update backlog as well

BugLink: https://bugs.launchpad.net/bugs/1810807

[ Upstream commit d7f4f332 ]

Fixes: 2ccccf5f ("net_sched: update hierarchical backlog too")
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/sched/sch_red.c

@@ -97,6 +97,7 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch)
 
 	ret = qdisc_enqueue(skb, child);
 	if (likely(ret == NET_XMIT_SUCCESS)) {
+		qdisc_qstats_backlog_inc(sch, skb);
 		sch->q.qlen++;
 	} else if (net_xmit_drop_count(ret)) {
 		q->stats.pdrop++;
@@ -118,6 +119,7 @@ static struct sk_buff *red_dequeue(struct Qdisc *sch)
 	skb = child->dequeue(child);
 	if (skb) {
 		qdisc_bstats_update(sch, skb);
+		qdisc_qstats_backlog_dec(sch, skb);
 		sch->q.qlen--;
 	} else {
 		if (!red_is_idling(&q->vars))
@@ -143,6 +145,7 @@ static unsigned int red_drop(struct Qdisc *sch)
 	if (child->ops->drop && (len = child->ops->drop(child)) > 0) {
 		q->stats.other++;
 		qdisc_qstats_drop(sch);
+		sch->qstats.backlog -= len;
 		sch->q.qlen--;
 		return len;
 	}
@@ -158,6 +161,7 @@ static void red_reset(struct Qdisc *sch)
 	struct red_sched_data *q = qdisc_priv(sch);
 
 	qdisc_reset(q->qdisc);
+	sch->qstats.backlog = 0;
 	sch->q.qlen = 0;
 	red_restart(&q->vars);
 }