[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, 5 insertions, 5 deletions

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index f76c20c0a109..c687388a8cb6 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1110,7 +1110,7 @@ static int htb_init(struct Qdisc *sch, struct rtattr *opt)
 static int htb_dump(struct Qdisc *sch, struct sk_buff *skb)
 {
         struct htb_sched *q = qdisc_priv(sch);
-        unsigned char *b = skb->tail;
+        unsigned char *b = skb_tail_pointer(skb);
         struct rtattr *rta;
         struct tc_htb_glob gopt;
         spin_lock_bh(&sch->dev->queue_lock);
@@ -1123,12 +1123,12 @@ static int htb_dump(struct Qdisc *sch, struct sk_buff *skb)
         rta = (struct rtattr *)b;
         RTA_PUT(skb, TCA_OPTIONS, 0, NULL);
         RTA_PUT(skb, TCA_HTB_INIT, sizeof(gopt), &gopt);
-        rta->rta_len = skb->tail - b;
+        rta->rta_len = skb_tail_pointer(skb) - b;
         spin_unlock_bh(&sch->dev->queue_lock);
         return skb->len;
 rtattr_failure:
         spin_unlock_bh(&sch->dev->queue_lock);
-        skb_trim(skb, skb->tail - skb->data);
+        skb_trim(skb, skb_tail_pointer(skb) - skb->data);
         return -1;
 }
 
@@ -1136,7 +1136,7 @@ static int htb_dump_class(struct Qdisc *sch, unsigned long arg,
                           struct sk_buff *skb, struct tcmsg *tcm)
 {
         struct htb_class *cl = (struct htb_class *)arg;
-        unsigned char *b = skb->tail;
+        unsigned char *b = skb_tail_pointer(skb);
         struct rtattr *rta;
         struct tc_htb_opt opt;
 
@@ -1159,7 +1159,7 @@ static int htb_dump_class(struct Qdisc *sch, unsigned long arg,
         opt.prio = cl->un.leaf.prio;
         opt.level = cl->level;
         RTA_PUT(skb, TCA_HTB_PARMS, sizeof(opt), &opt);
-        rta->rta_len = skb->tail - b;
+        rta->rta_len = skb_tail_pointer(skb) - b;
         spin_unlock_bh(&sch->dev->queue_lock);
         return skb->len;
 rtattr_failure: