[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, 1 insertions, 6 deletions

diff --git a/net/ipv4/netfilter/ip_conntrack_core.c b/net/ipv4/netfilter/ip_conntrack_core.c
index a7f0c821a9b202..04c3414361d405 100644
--- a/net/ipv4/netfilter/ip_conntrack_core.c
+++ b/net/ipv4/netfilter/ip_conntrack_core.c
@@ -625,9 +625,6 @@ unsigned int ip_conntrack_in(unsigned int hooknum,
 		return NF_DROP;
 	}
 
-	/* FIXME: Do this right please. --RR */
-	(*pskb)->nfcache |= NFC_UNKNOWN;
-
 /* Doesn't cover locally-generated broadcast, so not worth it. */
 #if 0
 	/* Ignore broadcast: no `connection'. */
@@ -943,10 +940,8 @@ ip_ct_gather_frags(struct sk_buff *skb, u_int32_t user)
 	skb = ip_defrag(skb, user);
 	local_bh_enable();
 
-	if (skb) {
+	if (skb)
 		ip_send_check(skb->nh.iph);
-		skb->nfcache |= NFC_ALTERED;
-	}
 	return skb;
 }