[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/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 50dc5edb7752..fdb6eb13cbcb 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -785,7 +785,7 @@ static inline struct sk_buff *netlink_trim(struct sk_buff *skb,
 
         skb_orphan(skb);
 
-        delta = skb->end - skb->tail;
+        delta = skb->end - skb_tail_pointer(skb);
         if (delta * 2 < skb->truesize)
                 return skb;