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>
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index a2a95aa..c412ad0 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -331,29 +331,22 @@
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 @@
/* 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 @@
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 @@
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 @@
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;