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Commit 960fb66e authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric 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: default avatarDavid S. Miller <davem@davemloft.net>
parent b94e52f6

net/sched/sch_netem.c

+15 −27
Original line number Original line Diff line number Diff line
@@ -331,17 +331,15 @@ static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sche 
	return PSCHED_NS2TICKS(ticks);

	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;

	struct sk_buff_head *list = &sch->q;

	psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;

	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 */

	/* Optimize for add at tail */

	if (likely(!skb || tnext >= netem_skb_cb(skb)->time_to_send))

	if (likely(!skb || tnext >= netem_skb_cb(skb)->time_to_send))

			return qdisc_enqueue_tail(nskb, sch);

		return __skb_queue_tail(list, nskb);





	skb_queue_reverse_walk(list, skb) {

	skb_queue_reverse_walk(list, skb) {

		if (tnext >= netem_skb_cb(skb)->time_to_send)

		if (tnext >= netem_skb_cb(skb)->time_to_send)
@@ -349,11 +347,6 @@ static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch) 
	}

	}





	__skb_queue_after(list, skb, nskb);

	__skb_queue_after(list, skb, nskb);

		sch->qstats.backlog += qdisc_pkt_len(nskb);

		return NET_XMIT_SUCCESS;

	}



	return qdisc_reshape_fail(nskb, sch);

}

}





/*

/*
@@ -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 */

	/* We don't fill cb now as skb_unshare() may invalidate it */

	struct netem_skb_cb *cb;

	struct netem_skb_cb *cb;

	struct sk_buff *skb2;

	struct sk_buff *skb2;

	int ret;

	int count = 1;

	int count = 1;





	/* Random duplication */

	/* 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);

		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);

	cb = netem_skb_cb(skb);

	if (q->gap == 0 ||		/* not doing reordering */

	if (q->gap == 0 ||		/* not doing reordering */

	    q->counter < q->gap - 1 ||	/* inside last reordering gap */

	    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;

		cb->time_to_send = now + delay;

		++q->counter;

		++q->counter;

		ret = tfifo_enqueue(skb, sch);

		tfifo_enqueue(skb, sch);

	} else {

	} else {

		/*

		/*

		 * Do re-ordering by putting one out of N packets at the front

		 * 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;

		q->counter = 0;





		__skb_queue_head(&sch->q, skb);

		__skb_queue_head(&sch->q, skb);

		sch->qstats.backlog += qdisc_pkt_len(skb);

		sch->qstats.requeues++;

		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;

	return NET_XMIT_SUCCESS;