[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_atm.c b/net/sched/sch_atm.c
index baca8743c12b..1d7bb1632138 100644
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -631,7 +631,7 @@ static int atm_tc_dump_class(struct Qdisc *sch, unsigned long cl,
 {
         struct atm_qdisc_data *p = PRIV(sch);
         struct atm_flow_data *flow = (struct atm_flow_data *) cl;
-        unsigned char *b = skb->tail;
+        unsigned char *b = skb_tail_pointer(skb);
         struct rtattr *rta;
 
         DPRINTK("atm_tc_dump_class(sch %p,[qdisc %p],flow %p,skb %p,tcm %p)\n",
@@ -661,7 +661,7 @@ static int atm_tc_dump_class(struct Qdisc *sch, unsigned long cl,
 
                 RTA_PUT(skb,TCA_ATM_EXCESS,sizeof(zero),&zero);
         }
-        rta->rta_len = skb->tail-b;
+        rta->rta_len = skb_tail_pointer(skb) - b;
         return skb->len;
 
 rtattr_failure: