Commit 0b441916 authored by Pavel Emelyanov's avatar Pavel Emelyanov Committed by David S. Miller
Browse files

netns: introduce the net_hash_mix "salt" for hashes 



There are many possible ways to add this "salt", thus I made this
patch to be the last in the series to change it if required.

Currently I propose to use the struct net pointer itself as this 
salt, but since this pointer is most often cache-line aligned, shift 
this right to eliminate the bits, that are most often zeroed.

After this, simply add this mix to prepared hashfn-s.

For CONFIG_NET_NS=n case this salt is 0 and no changes in hashfn
appear.

Signed-off-by: default avatarPavel Emelyanov <xemul@openvz.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 33de014c

include/linux/udp.h

+2 −1
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ struct udphdr { 
#ifdef __KERNEL__

#include <net/inet_sock.h>

#include <linux/skbuff.h>

#include <net/netns/hash.h>



static inline struct udphdr *udp_hdr(const struct sk_buff *skb)

{
@@ -48,7 +49,7 @@ static inline struct udphdr *udp_hdr(const struct sk_buff *skb) 


static inline int udp_hashfn(struct net *net, const unsigned num)

{

	return num & (UDP_HTABLE_SIZE - 1);

	return (num + net_hash_mix(net)) & (UDP_HTABLE_SIZE - 1);

}



struct udp_sock {

include/net/inet6_hashtables.h

+2 −1
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <net/inet_sock.h>



#include <net/ipv6.h>

#include <net/netns/hash.h>



struct inet_hashinfo;
@@ -36,7 +37,7 @@ static inline unsigned int inet6_ehashfn(struct net *net, 


	return jhash_3words((__force u32)laddr->s6_addr32[3],

			    (__force u32)faddr->s6_addr32[3],

			    ports, inet_ehash_secret);

			    ports, inet_ehash_secret + net_hash_mix(net));

}



static inline int inet6_sk_ehashfn(const struct sock *sk)

include/net/inet_hashtables.h

+3 −2
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <net/inet_sock.h>

#include <net/sock.h>

#include <net/tcp_states.h>

#include <net/netns/hash.h>



#include <asm/atomic.h>

#include <asm/byteorder.h>
@@ -204,7 +205,7 @@ extern void inet_bind_bucket_destroy(struct kmem_cache *cachep, 
static inline int inet_bhashfn(struct net *net,

		const __u16 lport, const int bhash_size)

{

	return lport & (bhash_size - 1);

	return (lport + net_hash_mix(net)) & (bhash_size - 1);

}



extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
@@ -213,7 +214,7 @@ extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, 
/* These can have wildcards, don't try too hard. */

static inline int inet_lhashfn(struct net *net, const unsigned short num)

{

	return num & (INET_LHTABLE_SIZE - 1);

	return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);

}



static inline int inet_sk_listen_hashfn(const struct sock *sk)

include/net/inet_sock.h

+2 −1
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <net/sock.h>

#include <net/request_sock.h>

#include <net/route.h>

#include <net/netns/hash.h>



/** struct ip_options - IP Options

 *
@@ -178,7 +179,7 @@ static inline unsigned int inet_ehashfn(struct net *net, 
	return jhash_3words((__force __u32) laddr,

			    (__force __u32) faddr,

			    ((__u32) lport) << 16 | (__force __u32)fport,

			    inet_ehash_secret);

			    inet_ehash_secret + net_hash_mix(net));

}



static inline int inet_sk_ehashfn(const struct sock *sk)

include/net/netns/hash.h

0 → 100644
+21 −0
Original line number Diff line number Diff line 
#ifndef __NET_NS_HASH_H__

#define __NET_NS_HASH_H__



#include <asm/cache.h>



struct net;



static inline unsigned net_hash_mix(struct net *net)

{

#ifdef CONFIG_NET_NS

	/*

	 * shift this right to eliminate bits, that are

	 * always zeroed

	 */



	return (unsigned)(((unsigned long)net) >> L1_CACHE_SHIFT);

#else

	return 0;

#endif

}

#endif

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