[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, 1 insertions, 1 deletions

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index a9d3ad5bc80f..68a632b372ec 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -229,7 +229,7 @@ __nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq, int type, int len, int flags)
                   (cb)->nlh->nlmsg_seq, type, len, flags)
 
 #define NLMSG_END(skb, nlh) \
-({      (nlh)->nlmsg_len = (skb)->tail - (unsigned char *) (nlh); \
+({      (nlh)->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)(nlh); \
         (skb)->len; })
 
 #define NLMSG_CANCEL(skb, nlh) \