igmp: avoid two atomic ops in igmp_rcv()
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>
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 250cb5e..3294f54 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -916,18 +916,19 @@
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 @@
case CHECKSUM_NONE:
skb->csum = 0;
if (__skb_checksum_complete(skb))
- goto drop_ref;
+ goto drop;
}
ih = igmp_hdr(skb);
@@ -957,7 +958,6 @@
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 @@
break;
}
-drop_ref:
- in_dev_put(in_dev);
drop:
kfree_skb(skb);
return 0;