Commit 6869c4d8 authored by Harald Welte's avatar Harald Welte Committed by David S. Miller
Browse files

[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: default avatarHarald Welte <laforge@netfilter.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bf3a46aa

include/linux/netfilter.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -21,10 +21,13 @@ 
#define NF_STOP 5

#define NF_STOP 5

#define NF_MAX_VERDICT NF_STOP

#define NF_MAX_VERDICT NF_STOP





/* only for userspace compatibility */

#ifndef __KERNEL__

/* Generic cache responses from hook functions.

/* Generic cache responses from hook functions.

   <= 0x2000 is used for protocol-flags. */

   <= 0x2000 is used for protocol-flags. */

#define NFC_UNKNOWN 0x4000

#define NFC_UNKNOWN 0x4000

#define NFC_ALTERED 0x8000

#define NFC_ALTERED 0x8000

#endif





#ifdef __KERNEL__

#ifdef __KERNEL__

#include <linux/config.h>

#include <linux/config.h>

include/linux/netfilter_decnet.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -9,6 +9,8 @@ 




#include <linux/netfilter.h>

#include <linux/netfilter.h>





/* only for userspace compatibility */

#ifndef __KERNEL__

/* IP Cache bits. */

/* IP Cache bits. */

/* Src IP address. */

/* Src IP address. */

#define NFC_DN_SRC		0x0001

#define NFC_DN_SRC		0x0001
@@ -18,6 +20,7 @@ 
#define NFC_DN_IF_IN		0x0004

#define NFC_DN_IF_IN		0x0004

/* Output device. */

/* Output device. */

#define NFC_DN_IF_OUT		0x0008

#define NFC_DN_IF_OUT		0x0008

#endif /* ! __KERNEL__ */





/* DECnet Hooks */

/* DECnet Hooks */

/* After promisc drops, checksum checks. */

/* After promisc drops, checksum checks. */

include/linux/netfilter_ipv4.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -8,6 +8,8 @@ 
#include <linux/config.h>

#include <linux/config.h>

#include <linux/netfilter.h>

#include <linux/netfilter.h>





/* only for userspace compatibility */

#ifndef __KERNEL__

/* IP Cache bits. */

/* IP Cache bits. */

/* Src IP address. */

/* Src IP address. */

#define NFC_IP_SRC		0x0001

#define NFC_IP_SRC		0x0001
@@ -35,6 +37,7 @@ 
#define NFC_IP_DST_PT		0x0400

#define NFC_IP_DST_PT		0x0400

/* Something else about the proto */

/* Something else about the proto */

#define NFC_IP_PROTO_UNKNOWN	0x2000

#define NFC_IP_PROTO_UNKNOWN	0x2000

#endif /* ! __KERNEL__ */





/* IP Hooks */

/* IP Hooks */

/* After promisc drops, checksum checks. */

/* After promisc drops, checksum checks. */

include/linux/netfilter_ipv6.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -10,6 +10,8 @@ 




#include <linux/netfilter.h>

#include <linux/netfilter.h>





/* only for userspace compatibility */

#ifndef __KERNEL__

/* IP Cache bits. */

/* IP Cache bits. */

/* Src IP address. */

/* Src IP address. */

#define NFC_IP6_SRC              0x0001

#define NFC_IP6_SRC              0x0001
@@ -38,6 +40,7 @@ 
#define NFC_IP6_DST_PT           0x0400

#define NFC_IP6_DST_PT           0x0400

/* Something else about the proto */

/* Something else about the proto */

#define NFC_IP6_PROTO_UNKNOWN    0x2000

#define NFC_IP6_PROTO_UNKNOWN    0x2000

#endif /* ! __KERNEL__ */









/* IP6 Hooks */

/* IP6 Hooks */

include/linux/skbuff.h

+5 −5
Original line number Original line Diff line number Diff line
@@ -190,7 +190,6 @@ struct skb_shared_info { 
 *	@end: End pointer

 *	@end: End pointer

 *	@destructor: Destruct function

 *	@destructor: Destruct function

 *	@nfmark: Can be used for communication between hooks

 *	@nfmark: Can be used for communication between hooks

 *	@nfcache: Cache info

 *	@nfct: Associated connection, if any

 *	@nfct: Associated connection, if any

 *	@nfctinfo: Relationship of this skb to the connection

 *	@nfctinfo: Relationship of this skb to the connection

 *	@nf_bridge: Saved data about a bridged frame - see br_netfilter.c

 *	@nf_bridge: Saved data about a bridged frame - see br_netfilter.c
@@ -252,17 +251,18 @@ struct sk_buff { 
	__u8			local_df:1,

	__u8			local_df:1,

				cloned:1,

				cloned:1,

				ip_summed:2,

				ip_summed:2,

				nohdr:1;

				nohdr:1,

				/* 3 bits spare */

				nfctinfo:3;

	__u8			pkt_type;

	__u8			pkt_type;

	__be16			protocol;

	__be16			protocol;





	void			(*destructor)(struct sk_buff *skb);

	void			(*destructor)(struct sk_buff *skb);

#ifdef CONFIG_NETFILTER

#ifdef CONFIG_NETFILTER

	__u32			nfmark;

	__u32			nfmark;

	__u32			nfcache;

	__u32			nfctinfo;

	struct nf_conntrack	*nfct;

	struct nf_conntrack	*nfct;

#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)

	__u8			ipvs_property:1;

#endif

#ifdef CONFIG_BRIDGE_NETFILTER

#ifdef CONFIG_BRIDGE_NETFILTER

	struct nf_bridge_info	*nf_bridge;

	struct nf_bridge_info	*nf_bridge;

#endif

#endif

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