[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/sched/cls_basic.c b/net/sched/cls_basic.c
index 4a91f082a81d..800ec2ac326b 100644
--- a/net/sched/cls_basic.c
+++ b/net/sched/cls_basic.c
@@ -245,7 +245,7 @@ static int basic_dump(struct tcf_proto *tp, unsigned long fh,
                       struct sk_buff *skb, struct tcmsg *t)
 {
         struct basic_filter *f = (struct basic_filter *) fh;
-        unsigned char *b = skb->tail;
+        unsigned char *b = skb_tail_pointer(skb);
         struct rtattr *rta;
 
         if (f == NULL)
@@ -263,7 +263,7 @@ static int basic_dump(struct tcf_proto *tp, unsigned long fh,
             tcf_em_tree_dump(skb, &f->ematches, TCA_BASIC_EMATCHES) < 0)
                 goto rtattr_failure;
 
-        rta->rta_len = (skb->tail - b);
+        rta->rta_len = skb_tail_pointer(skb) - b;
         return skb->len;
 
 rtattr_failure: