[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/decnet/dn_route.c b/net/decnet/dn_route.c
index bb73bf16630f..9678b096b844 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1468,7 +1468,7 @@ static int dn_rt_fill_info(struct sk_buff *skb, u32 pid, u32 seq,
         struct dn_route *rt = (struct dn_route *)skb->dst;
         struct rtmsg *r;
         struct nlmsghdr *nlh;
-        unsigned char *b = skb->tail;
+        unsigned char *b = skb_tail_pointer(skb);
         long expires;
 
         nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*r), flags);
@@ -1509,7 +1509,7 @@ static int dn_rt_fill_info(struct sk_buff *skb, u32 pid, u32 seq,
         if (rt->fl.iif)
                 RTA_PUT(skb, RTA_IIF, sizeof(int), &rt->fl.iif);
 
-        nlh->nlmsg_len = skb->tail - b;
+        nlh->nlmsg_len = skb_tail_pointer(skb) - b;
         return skb->len;
 
 nlmsg_failure: