[IPSEC]: Set skb->data to payload in x->mode->output

This patch changes the calling convention so that on entry from
x->mode->output and before entry into x->type->output skb->data
will point to the payload instead of the IP header.

This is essentially a redistribution of skb_push/skb_pull calls
with the aim of minimising them on the common path of tunnel +
ESP.

It'll also let us use the same calling convention between IPv4
and IPv6 with the next patch.

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

1 files changed, 2 insertions, 4 deletions

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 1af332df72d9..0f5e8387ccb4 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -28,9 +28,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
         int alen;
         int nfrags;
 
-        /* Strip IP+ESP header. */
-        __skb_pull(skb, skb_transport_offset(skb));
-        /* Now skb is pure payload to encrypt */
+        /* skb is pure payload to encrypt */
 
         err = -ENOMEM;
 
@@ -60,7 +58,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
         tail[clen - skb->len - 2] = (clen - skb->len) - 2;
         pskb_put(skb, trailer, clen - skb->len);
 
-        __skb_push(skb, -skb_network_offset(skb));
+        skb_push(skb, -skb_network_offset(skb));
         top_iph = ip_hdr(skb);
         esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
                                      top_iph->ihl * 4);