Commit 6c0d54f1 authored Jun 12, 2016 by Eric Dumazet Committed by David S. Miller Jun 14, 2016

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: 2ccccf5f ("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>

parent 881d0327

net/sched/sch_fifo.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}

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