[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, 1 deletions

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 8372f8b8f0cd..d38cbba92a4d 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -450,7 +450,8 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
          */
         iph = ip_hdr(skb_in);
 
-        if ((u8 *)iph < skb_in->head || (u8 *)(iph + 1) > skb_in->tail)
+        if ((u8 *)iph < skb_in->head ||
+            (skb_in->network_header + sizeof(*iph)) > skb_in->tail)
                 goto out;
 
         /*