linux-next/include/net/netns/hash.h

#ifndef __NET_NS_HASH_H__
#define __NET_NS_HASH_H__

#include <asm/cache.h>

struct net;

static inline u32 net_hash_mix(const struct net *net)
{
#ifdef CONFIG_NET_NS
	/*
	 * shift this right to eliminate bits, that are
	 * always zeroed
	 */

	return (u32)(((unsigned long)net) >> L1_CACHE_SHIFT);
#else
	return 0;
#endif
}
#endif
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> 2008-06-17 08:14:11 +08:00			`#ifndef __NET_NS_HASH_H__`
			`#define __NET_NS_HASH_H__`

			`#include <asm/cache.h>`

			`struct net;`

netns: constify net_hash_mix() and various callers const qualifiers ease code review by making clear which objects are not written in a function. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 2015-03-19 05:05:33 +08:00			`static inline u32 net_hash_mix(const struct net *net)`
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> 2008-06-17 08:14:11 +08:00			`{`
			`#ifdef CONFIG_NET_NS`
			`/*`
			`* shift this right to eliminate bits, that are`
			`* always zeroed`
			`*/`

netns: constify net_hash_mix() and various callers const qualifiers ease code review by making clear which objects are not written in a function. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> 2015-03-19 05:05:33 +08:00			`return (u32)(((unsigned long)net) >> L1_CACHE_SHIFT);`
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> 2008-06-17 08:14:11 +08:00			`#else`
			`return 0;`
			`#endif`
			`}`
			`#endif`