[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/sch_netem.c b/net/sched/sch_netem.c
index 915f82a2cc3d..2a9b1e429ff8 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -583,7 +583,7 @@ static void netem_destroy(struct Qdisc *sch)
 static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
         const struct netem_sched_data *q = qdisc_priv(sch);
-        unsigned char    *b = skb->tail;
+        unsigned char *b = skb_tail_pointer(skb);
         struct rtattr *rta = (struct rtattr *) b;
         struct tc_netem_qopt qopt;
         struct tc_netem_corr cor;
@@ -611,7 +611,7 @@ static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
         corrupt.correlation = q->corrupt_cor.rho;
         RTA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
 
-        rta->rta_len = skb->tail - b;
+        rta->rta_len = skb_tail_pointer(skb) - b;
 
         return skb->len;