net_sched: keep backlog updated with qlen

BugLink: https://bugs.launchpad.net/bugs/1878232

commit a27758ff upstream.

For gso_skb we only update qlen, backlog should be updated too.

Note, it is correct to just update these stats at one layer,
because the gso_skb is cached there.
Reported-by: Stas Nichiporovich <stasn77@gmail.com>
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

include/net/sch_generic.h

@@ -674,9 +674,11 @@ static inline struct sk_buff *qdisc_peek_dequeued(struct Qdisc *sch)
 	/* we can reuse ->gso_skb because peek isn't called for root qdiscs */
 	if (!sch->gso_skb) {
 		sch->gso_skb = sch->dequeue(sch);
-		if (sch->gso_skb)
+		if (sch->gso_skb) {
 			/* it's still part of the queue */
+			qdisc_qstats_backlog_inc(sch, sch->gso_skb);
 			sch->q.qlen++;
+		}
 	}
 
 	return sch->gso_skb;
@@ -689,6 +691,7 @@ static inline struct sk_buff *qdisc_dequeue_peeked(struct Qdisc *sch)
 
 	if (skb) {
 		sch->gso_skb = NULL;
+		qdisc_qstats_backlog_dec(sch, skb);
 		sch->q.qlen--;
 	} else {
 		skb = sch->dequeue(sch);

net/sched/sch_generic.c

@@ -49,6 +49,7 @@ static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
 {
 	q->gso_skb = skb;
 	q->qstats.requeues++;
+	qdisc_qstats_backlog_inc(q, skb);
 	q->q.qlen++;	/* it's still part of the queue */
 	__netif_schedule(q);
 
@@ -92,6 +93,7 @@ static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate,
 		txq = skb_get_tx_queue(txq->dev, skb);
 		if (!netif_xmit_frozen_or_stopped(txq)) {
 			q->gso_skb = NULL;
+			qdisc_qstats_backlog_dec(q, skb);
 			q->q.qlen--;
 		} else
 			skb = NULL;