[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, 2 insertions, 2 deletions

diff --git a/net/sctp/input.c b/net/sctp/input.c
index 1ff47b18724a..18b97eedc1fa 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -612,7 +612,7 @@ int sctp_rcv_ootb(struct sk_buff *skb)
                         break;
 
                 ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
-                if (ch_end > skb->tail)
+                if (ch_end > skb_tail_pointer(skb))
                         break;
 
                 /* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
@@ -644,7 +644,7 @@ int sctp_rcv_ootb(struct sk_buff *skb)
                 }
 
                 ch = (sctp_chunkhdr_t *) ch_end;
-        } while (ch_end < skb->tail);
+        } while (ch_end < skb_tail_pointer(skb));
 
         return 0;