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net_sched: fix pfifo_head_drop behavior vs backlog 

When the qdisc is full, we drop a packet at the head of the queue,
queue the current skb and return NET_XMIT_CN

Now we track backlog on upper qdiscs, we need to call
qdisc_tree_reduce_backlog(), even if the qlen did not change.

Fixes: 2ccccf5fb4 ("net_sched: update hierarchical backlog too")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-06-12 20:01:25 -07:00 committed by David S. Miller
parent 881d0327db
commit 6c0d54f189
1 changed files with 4 additions and 0 deletions
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4
net/sched/sch_fifo.c
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@ -37,14 +37,18 @@ static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch)
static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
unsigned int prev_backlog;
if (likely(skb_queue_len(&sch->q) < sch->limit))
return qdisc_enqueue_tail(skb, sch);
prev_backlog = sch->qstats.backlog;
/* queue full, remove one skb to fulfill the limit */
__qdisc_queue_drop_head(sch, &sch->q);
qdisc_qstats_drop(sch);
qdisc_enqueue_tail(skb, sch);
qdisc_tree_reduce_backlog(sch, 0, prev_backlog - sch->qstats.backlog);
return NET_XMIT_CN;
}