netdev - [PATCH net-next] fq_codel: fix memory limitation drift

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Date:	Sun, 15 May 2016 18:16:38 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	Jesper Dangaard Brouer <brouer@...hat.com>,
	Dave Täht <dave.taht@...il.com>,
	netdev <netdev@...r.kernel.org>, moeller0 <moeller0@....de>
Subject: [PATCH net-next] fq_codel: fix memory limitation drift

From: Eric Dumazet <edumazet@...gle.com>

memory_usage must be decreased in dequeue_func(), not in
fq_codel_dequeue(), otherwise packets dropped by Codel algo
are missing this decrease.

Also we need to clear memory_usage in fq_codel_reset()

Fixes: 95b58430abe7 ("fq_codel: add memory limitation per queue")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/sched/sch_fq_codel.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index bb8bd9314629..6883a8971562 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -262,6 +262,7 @@ static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx)
 	if (flow->head) {
 		skb = dequeue_head(flow);
 		q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
+		q->memory_usage -= skb->truesize;
 		sch->q.qlen--;
 		sch->qstats.backlog -= qdisc_pkt_len(skb);
 	}
@@ -318,7 +319,6 @@ begin:
 			list_del_init(&flow->flowchain);
 		goto begin;
 	}
-	q->memory_usage -= skb->truesize;
 	qdisc_bstats_update(sch, skb);
 	flow->deficit -= qdisc_pkt_len(skb);
 	/* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
@@ -355,6 +355,7 @@ static void fq_codel_reset(struct Qdisc *sch)
 	}
 	memset(q->backlogs, 0, q->flows_cnt * sizeof(u32));
 	sch->q.qlen = 0;
+	q->memory_usage = 0;
 }
 
 static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = {