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igmp: avoid two atomic ops in igmp_rcv()

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

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-06-07 03:17:10 +00:00 committed by David S. Miller
parent 66018506e1
commit 9a57a9d291
1 changed files with 4 additions and 6 deletions
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10
net/ipv4/igmp.c
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@ -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); read_unlock(&in_dev->mc_list_lock);
} }
/* called in rcu_read_lock() section */
int igmp_rcv(struct sk_buff *skb) int igmp_rcv(struct sk_buff *skb)
{ {
/* This basically follows the spec line by line -- see RFC1112 */ /* This basically follows the spec line by line -- see RFC1112 */
struct igmphdr *ih; 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; int len = skb->len;
if (in_dev == NULL) if (in_dev == NULL)
goto drop; goto drop;
if (!pskb_may_pull(skb, sizeof(struct igmphdr))) if (!pskb_may_pull(skb, sizeof(struct igmphdr)))
goto drop_ref; goto drop;
switch (skb->ip_summed) { switch (skb->ip_summed) {
case CHECKSUM_COMPLETE: case CHECKSUM_COMPLETE:
@ -937,7 +938,7 @@ int igmp_rcv(struct sk_buff *skb)
case CHECKSUM_NONE: case CHECKSUM_NONE:
skb->csum = 0; skb->csum = 0;
if (__skb_checksum_complete(skb)) if (__skb_checksum_complete(skb))
goto drop_ref; goto drop;
} }
ih = igmp_hdr(skb); ih = igmp_hdr(skb);
@ -957,7 +958,6 @@ int igmp_rcv(struct sk_buff *skb)
break; break;
case IGMP_PIM: case IGMP_PIM:
#ifdef CONFIG_IP_PIMSM_V1 #ifdef CONFIG_IP_PIMSM_V1
in_dev_put(in_dev);
return pim_rcv_v1(skb); return pim_rcv_v1(skb);
#endif #endif
case IGMPV3_HOST_MEMBERSHIP_REPORT: case IGMPV3_HOST_MEMBERSHIP_REPORT:
@ -971,8 +971,6 @@ int igmp_rcv(struct sk_buff *skb)
break; break;
} }
drop_ref:
in_dev_put(in_dev);
drop: drop:
kfree_skb(skb); kfree_skb(skb);
return 0; return 0;