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linux-2.6/include/net/netns/hash.h
Pavel Emelyanov 0b4419162a 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: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-16 17:14:11 -07:00

22 lines
336 B
C

#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