[IPV6]: Avoid skb_copy/pskb_copy/skb_realloc_headroom on input

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>

1 files changed, 5 insertions, 18 deletions

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index c82d4d49f71f..0ff2bf12ecd1 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -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)