[IPV6]: Avoid skb_copy/pskb_copy/skb_realloc_headroom on input
Herbert Xu [Mon, 15 Oct 2007 08:29:10 +0000 (01:29 -0700)]
This patch replaces unnecessary uses of skb_copy by pskb_expand_head
on the IPv6 input path.

This allows us to remove the double pointers later.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/exthdrs.c

index c82d4d4..0ff2bf1 100644 (file)
@@ -234,22 +234,13 @@ static int ipv6_dest_hao(struct sk_buff **skbp, int optoff)
                goto discard;
 
        if (skb_cloned(skb)) {
-               struct sk_buff *skb2 = skb_copy(skb, GFP_ATOMIC);
-               struct inet6_skb_parm *opt2;
-
-               if (skb2 == NULL)
+               if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
                        goto discard;
 
-               opt2 = IP6CB(skb2);
-               memcpy(opt2, opt, sizeof(*opt2));
-
-               kfree_skb(skb);
-
                /* update all variable using below by copied skbuff */
-               *skbp = skb = skb2;
-               hao = (struct ipv6_destopt_hao *)(skb_network_header(skb2) +
+               hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
                                                  optoff);
-               ipv6h = ipv6_hdr(skb2);
+               ipv6h = ipv6_hdr(skb);
        }
 
        if (skb->ip_summed == CHECKSUM_COMPLETE)
@@ -464,18 +455,14 @@ looped_back:
           Do not damage packets queued somewhere.
         */
        if (skb_cloned(skb)) {
-               struct sk_buff *skb2 = skb_copy(skb, GFP_ATOMIC);
                /* the copy is a forwarded packet */
-               if (skb2 == NULL) {
+               if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
                        IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
                                         IPSTATS_MIB_OUTDISCARDS);
                        kfree_skb(skb);
                        return -1;
                }
-               kfree_skb(skb);
-               *skbp = skb = skb2;
-               opt = IP6CB(skb2);
-               hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb2);
+               hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
        }
 
        if (skb->ip_summed == CHECKSUM_COMPLETE)