[NETFILTER]: reduce netfilter sk_buff enlargement

As discussed at netconf'05, we're trying to save every bit in sk_buff.
The patch below makes sk_buff 8 bytes smaller.  I did some basic
testing on my notebook and it seems to work.

The only real in-tree user of nfcache was IPVS, who only needs a
single bit.  Unfortunately I couldn't find some other free bit in
sk_buff to stuff that bit into, so I introduced a separate field for
them.  Maybe the IPVS guys can resolve that to further save space.

Initially I wanted to shrink pkt_type to three bits (PACKET_HOST and
alike are only 6 values defined), but unfortunately the bluetooth code
overloads pkt_type :(

The conntrack-event-api (out-of-tree) uses nfcache, but Rusty just
came up with a way how to do it without any skb fields, so it's safe
to remove it.

- remove all never-implemented 'nfcache' code
- don't have ipvs code abuse 'nfcache' field. currently get's their own
  compile-conditional skb->ipvs_property field.  IPVS maintainers can
  decide to move this bit elswhere, but nfcache needs to die.
- remove skb->nfcache field to save 4 bytes
- move skb->nfctinfo into three unused bits to save further 4 bytes

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 2 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7eab867ede59..096991cb09d9 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -361,7 +361,6 @@ struct sk_buff *skb_clone(struct sk_buff *skb, unsigned int __nocast gfp_mask)
         n->destructor = NULL;
 #ifdef CONFIG_NETFILTER
         C(nfmark);
-        C(nfcache);
         C(nfct);
         nf_conntrack_get(skb->nfct);
         C(nfctinfo);
@@ -424,7 +423,6 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
         new->destructor = NULL;
 #ifdef CONFIG_NETFILTER
         new->nfmark     = old->nfmark;
-        new->nfcache    = old->nfcache;
         new->nfct       = old->nfct;
         nf_conntrack_get(old->nfct);
         new->nfctinfo   = old->nfctinfo;