[SK_BUFF]: Convert skb->tail to sk_buff_data_t

So that it is also an offset from skb->head, reduces its size from 8 to 4 bytes
on 64bit architectures, allowing us to combine the 4 bytes hole left by the
layer headers conversion, reducing struct sk_buff size to 256 bytes, i.e. 4
64byte cachelines, and since the sk_buff slab cache is SLAB_HWCACHE_ALIGN...
:-)

Many calculations that previously required that skb->{transport,network,
mac}_header be first converted to a pointer now can be done directly, being
meaningful as offsets or pointers.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 6562e5736e2f..86dc9f693f66 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1069,7 +1069,7 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
                         skb_reset_mac_header(skb2);
 
                         if (skb_network_header(skb2) < skb2->data ||
-                            skb_network_header(skb2) > skb2->tail) {
+                            skb2->network_header > skb2->tail) {
                                 if (net_ratelimit())
                                         printk(KERN_CRIT "protocol %04x is "
                                                "buggy, dev %s\n",
@@ -1175,7 +1175,7 @@ int skb_checksum_help(struct sk_buff *skb)
         BUG_ON(offset > (int)skb->len);
         csum = skb_checksum(skb, offset, skb->len-offset, 0);
 
-        offset = skb->tail - skb_transport_header(skb);
+        offset = skb->tail - skb->transport_header;
         BUG_ON(offset <= 0);
         BUG_ON(skb->csum_offset + 2 > offset);