[RFT] remove skb_linearize from igmp.c

[Stephen Hemminger <shemminger@xxxxxxxx>]

This patch gets rid of the deprecated skb_linearize call in IGMP by
using pskb_may_pull like ip_input does.

Could someone who actually receives IGMP packets test this?

diff -Nru a/net/ipv4/igmp.c b/net/ipv4/igmp.c
--- a/net/ipv4/igmp.c   Mon Jun 23 11:59:56 2003
+++ b/net/ipv4/igmp.c   Mon Jun 23 11:59:56 2003
@@ -838,28 +838,19 @@
 int igmp_rcv(struct sk_buff *skb)
 {
        /* This basically follows the spec line by line -- see RFC1112 */
-       struct igmphdr *ih = skb->h.igmph;
+       struct igmphdr *ih;
        struct in_device *in_dev = in_dev_get(skb->dev);
        int len = skb->len;
 
-       if (in_dev==NULL) {
-               kfree_skb(skb);
-               return 0;
-       }
-
-       if (skb_is_nonlinear(skb)) {
-               if (skb_linearize(skb, GFP_ATOMIC) != 0) {
-                       kfree_skb(skb);
-                       return -ENOMEM;
-               }
-               ih = skb->h.igmph;
-       }
+       if (in_dev==NULL) 
+               goto out;
 
-       if (len < sizeof(struct igmphdr) || ip_compute_csum((void *)ih, len)) {
-               in_dev_put(in_dev);
-               kfree_skb(skb);
-               return 0;
-       }
+       if (!pskb_may_pull(skb, sizeof(struct igmphdr)))
+               goto drop;
+       
+       ih = skb->h.igmph;
+       if (ip_compute_csum((void *)ih, len)) 
+               goto drop;
 
        switch (ih->type) {
        case IGMP_HOST_MEMBERSHIP_QUERY:
@@ -887,7 +878,9 @@
        default:
                NETDEBUG(printk(KERN_DEBUG "New IGMP type=%d, why we do not 
know about it?\n", ih->type));
        }
+ drop:
        in_dev_put(in_dev);
+ out:
        kfree_skb(skb);
        return 0;
 }