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[NET_SCHED]: Fix endless loops (part 5): netem/tbf/hfsc ->requeue failures 

When peeking at the next packet in a child qdisc by calling dequeue/requeue,
the upper qdisc qlen counter may get out of sync in case the requeue fails.
The qdisc and the child qdisc both have their counter decremented, but since
no packet is given to the upper qdisc it won't decrement its counter itself.

requeue should not fail, so this is mostly for "correctness".

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Patrick McHardy 2006-11-29 17:37:42 -08:00 committed by David S. Miller
parent 256d61b87b
commit e488eafcc5
3 changed files with 3 additions and 5 deletions
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1
net/sched/sch_hfsc.c
View File

@ -946,6 +946,7 @@ qdisc_peek_len(struct Qdisc *sch)
if (unlikely(sch->ops->requeue(skb, sch) != NET_XMIT_SUCCESS)) {
if (net_ratelimit())
printk("qdisc_peek_len: failed to requeue\n");
qdisc_tree_decrease_qlen(sch, 1);
return 0;
}
return len;

5
net/sched/sch_netem.c
View File

@ -287,13 +287,10 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
psched_tdiff_t delay = PSCHED_TDIFF(cb->time_to_send, now);
if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
qdisc_tree_decrease_qlen(q->qdisc, 1);
sch->qstats.drops++;
/* After this qlen is confused */
printk(KERN_ERR "netem: queue discpline %s could not requeue\n",
q->qdisc->ops->id);
sch->q.qlen--;
}
mod_timer(&q->timer, jiffies + PSCHED_US2JIFFIE(delay));

2
net/sched/sch_tbf.c
View File

@ -250,7 +250,7 @@ static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
/* When requeue fails skb is dropped */
sch->q.qlen--;
qdisc_tree_decrease_qlen(q->qdisc, 1);
sch->qstats.drops++;
}