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Commit 9a57a9d2 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

igmp: avoid two atomic ops in igmp_rcv() 



in_dev_get() -> __in_dev_get_rcu() in a rcu protected function.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 66018506

net/ipv4/igmp.c

+4 −6
Original line number Diff line number Diff line
@@ -916,18 +916,19 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb, 
	read_unlock(&in_dev->mc_list_lock);

}



/* called in rcu_read_lock() section */

int igmp_rcv(struct sk_buff *skb)

{

	/* This basically follows the spec line by line -- see RFC1112 */

	struct igmphdr *ih;

	struct in_device *in_dev = in_dev_get(skb->dev);

	struct in_device *in_dev = __in_dev_get_rcu(skb->dev);

	int len = skb->len;



	if (in_dev == NULL)

		goto drop;



	if (!pskb_may_pull(skb, sizeof(struct igmphdr)))

		goto drop_ref;

		goto drop;



	switch (skb->ip_summed) {

	case CHECKSUM_COMPLETE:
@@ -937,7 +938,7 @@ int igmp_rcv(struct sk_buff *skb) 
	case CHECKSUM_NONE:

		skb->csum = 0;

		if (__skb_checksum_complete(skb))

			goto drop_ref;

			goto drop;

	}



	ih = igmp_hdr(skb);
@@ -957,7 +958,6 @@ int igmp_rcv(struct sk_buff *skb) 
		break;

	case IGMP_PIM:

#ifdef CONFIG_IP_PIMSM_V1

		in_dev_put(in_dev);

		return pim_rcv_v1(skb);

#endif

	case IGMPV3_HOST_MEMBERSHIP_REPORT:
@@ -971,8 +971,6 @@ int igmp_rcv(struct sk_buff *skb) 
		break;

	}



drop_ref:

	in_dev_put(in_dev);

drop:

	kfree_skb(skb);

	return 0;