[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/drivers/net/wan/hdlc_fr.c b/drivers/net/wan/hdlc_fr.c
index b747228..aeb2789 100644
--- a/drivers/net/wan/hdlc_fr.c
+++ b/drivers/net/wan/hdlc_fr.c
@@ -533,7 +533,7 @@
skb->protocol = __constant_htons(NLPID_CCITT_ANSI_LMI);
fr_hard_header(&skb, LMI_CCITT_ANSI_DLCI);
}
- data = skb->tail;
+ data = skb_tail_pointer(skb);
data[i++] = LMI_CALLREF;
data[i++] = dce ? LMI_STATUS : LMI_STATUS_ENQUIRY;
if (lmi == LMI_ANSI)