[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>

2 files changed, 2 insertions, 2 deletions

diff --git a/net/tipc/config.c b/net/tipc/config.c
index 14789a82de53..c71337a22d33 100644
--- a/net/tipc/config.c
+++ b/net/tipc/config.c
@@ -89,7 +89,7 @@ struct sk_buff *tipc_cfg_reply_alloc(int payload_size)
 int tipc_cfg_append_tlv(struct sk_buff *buf, int tlv_type,
                         void *tlv_data, int tlv_data_size)
 {
-        struct tlv_desc *tlv = (struct tlv_desc *)buf->tail;
+        struct tlv_desc *tlv = (struct tlv_desc *)skb_tail_pointer(buf);
         int new_tlv_space = TLV_SPACE(tlv_data_size);
 
         if (skb_tailroom(buf) < new_tlv_space) {
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index b71739fbe2c6..45832fb75ea4 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1020,7 +1020,7 @@ restart:
 
         if (!err) {
                 buf_crs = (unsigned char *)(TIPC_SKB_CB(buf)->handle);
-                sz = buf->tail - buf_crs;
+                sz = skb_tail_pointer(buf) - buf_crs;
 
                 needed = (buf_len - sz_copied);
                 sz_to_copy = (sz <= needed) ? sz : needed;