[PATCH 4.4 087/312] net_sched: keep backlog updated with qlen

From: Greg Kroah-Hartman
Date: Fri May 08 2020 - 08:40:09 EST


From: WANG Cong <xiyou.wangcong@xxxxxxxxx>

commit a27758ffaf96f89002129eedb2cc172d254099f8 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@xxxxxxxxx>
Fixes: 2ccccf5fb43f ("net_sched: update hierarchical backlog too")
Cc: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
include/net/sch_generic.h | 5 ++++-
net/sched/sch_generic.c | 2 ++
2 files changed, 6 insertions(+), 1 deletion(-)

--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -674,9 +674,11 @@ static inline struct sk_buff *qdisc_peek
/* 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_dequ

if (skb) {
sch->gso_skb = NULL;
+ qdisc_qstats_backlog_dec(sch, skb);
sch->q.qlen--;
} else {
skb = sch->dequeue(sch);
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -49,6 +49,7 @@ static inline int dev_requeue_skb(struct
{
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(struc
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;