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netem: add limitation to reordered packets 

Fix two netem bugs :

1) When a frame was dropped by tfifo_enqueue(), drop counter
   was incremented twice.

2) When reordering is triggered, we enqueue a packet without
   checking queue limit. This can OOM pretty fast when this
   is repeated enough, since skbs are orphaned, no socket limit
   can help in this situation.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Mark Gordon <msg@google.com>
Cc: Andreas Terzis <aterzis@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2012-07-03 20:55:21 +00:00 committed by David S. Miller
parent b94e52f626
commit 960fb66e52
1 changed files with 15 additions and 27 deletions
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42
net/sched/sch_netem.c
View File

@ -331,29 +331,22 @@ static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sche
return PSCHED_NS2TICKS(ticks);
}
static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
{
struct sk_buff_head *list = &sch->q;
psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
struct sk_buff *skb;
struct sk_buff *skb = skb_peek_tail(list);
if (likely(skb_queue_len(list) < sch->limit)) {
skb = skb_peek_tail(list);
/* Optimize for add at tail */
if (likely(!skb || tnext >= netem_skb_cb(skb)->time_to_send))
return qdisc_enqueue_tail(nskb, sch);
/* Optimize for add at tail */
if (likely(!skb || tnext >= netem_skb_cb(skb)->time_to_send))
return __skb_queue_tail(list, nskb);
skb_queue_reverse_walk(list, skb) {
if (tnext >= netem_skb_cb(skb)->time_to_send)
break;
}
__skb_queue_after(list, skb, nskb);
sch->qstats.backlog += qdisc_pkt_len(nskb);
return NET_XMIT_SUCCESS;
skb_queue_reverse_walk(list, skb) {
if (tnext >= netem_skb_cb(skb)->time_to_send)
break;
}
return qdisc_reshape_fail(nskb, sch);
__skb_queue_after(list, skb, nskb);
}
/*
@ -368,7 +361,6 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
/* We don't fill cb now as skb_unshare() may invalidate it */
struct netem_skb_cb *cb;
struct sk_buff *skb2;
int ret;
int count = 1;
/* Random duplication */
@ -419,6 +411,11 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
}
if (unlikely(skb_queue_len(&sch->q) >= sch->limit))
return qdisc_reshape_fail(skb, sch);
sch->qstats.backlog += qdisc_pkt_len(skb);
cb = netem_skb_cb(skb);
if (q->gap == 0 || /* not doing reordering */
q->counter < q->gap - 1 || /* inside last reordering gap */
@ -450,7 +447,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
cb->time_to_send = now + delay;
++q->counter;
ret = tfifo_enqueue(skb, sch);
tfifo_enqueue(skb, sch);
} else {
/*
* Do re-ordering by putting one out of N packets at the front
@ -460,16 +457,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
q->counter = 0;
__skb_queue_head(&sch->q, skb);
sch->qstats.backlog += qdisc_pkt_len(skb);
sch->qstats.requeues++;
ret = NET_XMIT_SUCCESS;
}
if (ret != NET_XMIT_SUCCESS) {
if (net_xmit_drop_count(ret)) {
sch->qstats.drops++;
return ret;
}
}
return NET_XMIT_SUCCESS;