[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, 7 insertions, 7 deletions

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 5c6ffdb77d2d..84231baf77d1 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -323,7 +323,7 @@ tcf_fill_node(struct sk_buff *skb, struct tcf_proto *tp, unsigned long fh,
 {
         struct tcmsg *tcm;
         struct nlmsghdr  *nlh;
-        unsigned char    *b = skb->tail;
+        unsigned char *b = skb_tail_pointer(skb);
 
         nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*tcm), flags);
         tcm = NLMSG_DATA(nlh);
@@ -340,7 +340,7 @@ tcf_fill_node(struct sk_buff *skb, struct tcf_proto *tp, unsigned long fh,
                 if (tp->ops->dump && tp->ops->dump(tp, fh, skb, tcm) < 0)
                         goto rtattr_failure;
         }
-        nlh->nlmsg_len = skb->tail - b;
+        nlh->nlmsg_len = skb_tail_pointer(skb) - b;
         return skb->len;
 
 nlmsg_failure:
@@ -563,30 +563,30 @@ tcf_exts_dump(struct sk_buff *skb, struct tcf_exts *exts,
                  * to work with both old and new modes of entering
                  * tc data even if iproute2  was newer - jhs
                  */
-                struct rtattr * p_rta = (struct rtattr*) skb->tail;
+                struct rtattr *p_rta = (struct rtattr *)skb_tail_pointer(skb);
 
                 if (exts->action->type != TCA_OLD_COMPAT) {
                         RTA_PUT(skb, map->action, 0, NULL);
                         if (tcf_action_dump(skb, exts->action, 0, 0) < 0)
                                 goto rtattr_failure;
-                        p_rta->rta_len = skb->tail - (u8*)p_rta;
+                        p_rta->rta_len = skb_tail_pointer(skb) - (u8 *)p_rta;
                 } else if (map->police) {
                         RTA_PUT(skb, map->police, 0, NULL);
                         if (tcf_action_dump_old(skb, exts->action, 0, 0) < 0)
                                 goto rtattr_failure;
-                        p_rta->rta_len = skb->tail - (u8*)p_rta;
+                        p_rta->rta_len = skb_tail_pointer(skb) - (u8 *)p_rta;
                 }
         }
 #elif defined CONFIG_NET_CLS_POLICE
         if (map->police && exts->police) {
-                struct rtattr * p_rta = (struct rtattr*) skb->tail;
+                struct rtattr *p_rta = (struct rtattr *)skb_tail_pointer(skb);
 
                 RTA_PUT(skb, map->police, 0, NULL);
 
                 if (tcf_police_dump(skb, exts->police) < 0)
                         goto rtattr_failure;
 
-                p_rta->rta_len = skb->tail - (u8*)p_rta;
+                p_rta->rta_len = skb_tail_pointer(skb) - (u8 *)p_rta;
         }
 #endif
         return 0;