[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, 4 deletions

diff --git a/include/net/inet_ecn.h b/include/net/inet_ecn.h
index 06a2c69a89e5..de8399a79774 100644
--- a/include/net/inet_ecn.h
+++ b/include/net/inet_ecn.h
@@ -114,14 +114,12 @@ static inline int INET_ECN_set_ce(struct sk_buff *skb)
 {
         switch (skb->protocol) {
         case __constant_htons(ETH_P_IP):
-                if (skb_network_header(skb) + sizeof(struct iphdr) <=
-                    skb->tail)
+                if (skb->network_header + sizeof(struct iphdr) <= skb->tail)
                         return IP_ECN_set_ce(ip_hdr(skb));
                 break;
 
         case __constant_htons(ETH_P_IPV6):
-                if (skb_network_header(skb) + sizeof(struct ipv6hdr) <=
-                    skb->tail)
+                if (skb->network_header + sizeof(struct ipv6hdr) <= skb->tail)
                         return IP6_ECN_set_ce(ipv6_hdr(skb));
                 break;
         }