Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 078/109] netem: add limitation to reordered packets | Date | Tue, 7 Aug 2012 15:35:37 -0700 |
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From: Greg KH <gregkh@linuxfoundation.org>
3.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
[ Upstream commit 960fb66e520a405dde39ff883f17ff2669c13d85 ]
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/sched/sch_netem.c | 42 +++++++++++++++--------------------------- 1 file changed, 15 insertions(+), 27 deletions(-)
--- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -329,29 +329,22 @@ static psched_time_t packet_len_2_sched_ 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); - - skb_queue_reverse_walk(list, skb) { - if (tnext >= netem_skb_cb(skb)->time_to_send) - break; - } + /* Optimize for add at tail */ + if (likely(!skb || tnext >= netem_skb_cb(skb)->time_to_send)) + return __skb_queue_tail(list, nskb); - __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); } /* @@ -366,7 +359,6 @@ static int netem_enqueue(struct sk_buff /* 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 */ @@ -414,6 +406,11 @@ static int netem_enqueue(struct sk_buff 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 */ @@ -445,7 +442,7 @@ static int netem_enqueue(struct sk_buff 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 @@ -455,16 +452,7 @@ static int netem_enqueue(struct sk_buff 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;
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