[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_fw.c b/net/sched/cls_fw.c
index 5dbb9d451f73..f5f355852a87 100644
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -348,7 +348,7 @@ static int fw_dump(struct tcf_proto *tp, unsigned long fh,
 {
         struct fw_head *head = (struct fw_head *)tp->root;
         struct fw_filter *f = (struct fw_filter*)fh;
-        unsigned char    *b = skb->tail;
+        unsigned char *b = skb_tail_pointer(skb);
         struct rtattr *rta;
 
         if (f == NULL)
@@ -374,7 +374,7 @@ static int fw_dump(struct tcf_proto *tp, unsigned long fh,
         if (tcf_exts_dump(skb, &f->exts, &fw_ext_map) < 0)
                 goto rtattr_failure;
 
-        rta->rta_len = skb->tail - b;
+        rta->rta_len = skb_tail_pointer(skb) - b;
 
         if (tcf_exts_dump_stats(skb, &f->exts, &fw_ext_map) < 0)
                 goto rtattr_failure;