[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>
diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index bb73bf1..9678b09 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -1468,7 +1468,7 @@
struct dn_route *rt = (struct dn_route *)skb->dst;
struct rtmsg *r;
struct nlmsghdr *nlh;
- unsigned char *b = skb->tail;
+ unsigned char *b = skb_tail_pointer(skb);
long expires;
nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*r), flags);
@@ -1509,7 +1509,7 @@
if (rt->fl.iif)
RTA_PUT(skb, RTA_IIF, sizeof(int), &rt->fl.iif);
- nlh->nlmsg_len = skb->tail - b;
+ nlh->nlmsg_len = skb_tail_pointer(skb) - b;
return skb->len;
nlmsg_failure: