[PATCH] netem: fix dequeue

[PATCH] netem: fix dequeue

[Eric Dumazet]

commit 50612537e9 (netem: fix classful handling) added two errors in
netem_dequeue() 

1) After checking skb at the head of tfifo queue for time constraints,
   it dequeues tail skb, thus adding unwanted reordering.

2) qdisc stats are updated twice per packet
   (one when packet dequeued from tfifo, once when delivered)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
 net/sched/sch_netem.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index e83d61c..5da548f 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -501,9 +501,8 @@ tfifo_dequeue:
 
 		/* if more time remaining? */
 		if (cb->time_to_send <= psched_get_time()) {
-			skb = qdisc_dequeue_tail(sch);
-			if (unlikely(!skb))
-				goto qdisc_dequeue;
+			__skb_unlink(skb, &sch->q);
+			sch->qstats.backlog -= qdisc_pkt_len(skb);
 
 #ifdef CONFIG_NET_CLS_ACT
 			/*
@@ -539,7 +538,6 @@ deliver:
 		qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
 	}
 
-qdisc_dequeue:
 	if (q->qdisc) {
 		skb = q->qdisc->ops->dequeue(q->qdisc);
 		if (skb)

Re: [PATCH] netem: fix dequeue

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 16 Feb 2012 07:28:25 +0100

> commit 50612537e9 (netem: fix classful handling) added two errors in
> netem_dequeue() 
> 
> 1) After checking skb at the head of tfifo queue for time constraints,
>    it dequeues tail skb, thus adding unwanted reordering.
> 
> 2) qdisc stats are updated twice per packet
>    (one when packet dequeued from tfifo, once when delivered)
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied.