[NETFILTER]: Do not copy skb in skb_make_writable

Now that all callers of netfilter can guarantee that the skb is not shared,
we no longer have to copy the skb in skb_make_writable.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/nf_nat_helper.c b/net/ipv4/netfilter/nf_nat_helper.c
index 93d8a0a..6e81f76 100644
--- a/net/ipv4/netfilter/nf_nat_helper.c
+++ b/net/ipv4/netfilter/nf_nat_helper.c
@@ -152,7 +152,7 @@
 	struct tcphdr *tcph;
 	int oldlen, datalen;
 
-	if (!skb_make_writable(pskb, (*pskb)->len))
+	if (!skb_make_writable(*pskb, (*pskb)->len))
 		return 0;
 
 	if (rep_len > match_len &&
@@ -234,7 +234,7 @@
 			       match_offset + match_len)
 		return 0;
 
-	if (!skb_make_writable(pskb, (*pskb)->len))
+	if (!skb_make_writable(*pskb, (*pskb)->len))
 		return 0;
 
 	if (rep_len > match_len &&
@@ -341,7 +341,7 @@
 	optoff = ip_hdrlen(*pskb) + sizeof(struct tcphdr);
 	optend = ip_hdrlen(*pskb) + tcph->doff * 4;
 
-	if (!skb_make_writable(pskb, optend))
+	if (!skb_make_writable(*pskb, optend))
 		return 0;
 
 	dir = CTINFO2DIR(ctinfo);
@@ -390,7 +390,7 @@
 	this_way = &nat->seq[dir];
 	other_way = &nat->seq[!dir];
 
-	if (!skb_make_writable(pskb, ip_hdrlen(*pskb) + sizeof(*tcph)))
+	if (!skb_make_writable(*pskb, ip_hdrlen(*pskb) + sizeof(*tcph)))
 		return 0;
 
 	tcph = (void *)(*pskb)->data + ip_hdrlen(*pskb);