[PATCH 1/6] hash: Introduce ptr_hash_mix routine
From: Pavel Emelyanov <hidden>
Date: 2012-08-06 14:13:53
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
This one is used to make a salt out of a pointer to be mixed to some hash function later. Idea and implementation are proposed by Eric Dumazet. Signed-off-by: Pavel Emelyanov <redacted> --- include/linux/hash.h | 10 ++++++++++ include/net/netns/hash.h | 9 ++------- 2 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/include/linux/hash.h b/include/linux/hash.h
index b80506b..1bd0ab1 100644
--- a/include/linux/hash.h
+++ b/include/linux/hash.h@@ -14,6 +14,7 @@ * machines where multiplications are slow. */ +#include <linux/cache.h> #include <asm/types.h> /* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
@@ -67,4 +68,13 @@ static inline unsigned long hash_ptr(const void *ptr, unsigned int bits) { return hash_long((unsigned long)ptr, bits); } + +static inline u32 ptr_hash_mix(const void *ptr) +{ +#if BITS_PER_LONG == 32 + return (u32)(unsigned long)ptr; +#else + return (u32)((unsigned long)ptr >> L1_CACHE_SHIFT); +#endif +} #endif /* _LINUX_HASH_H */
diff --git a/include/net/netns/hash.h b/include/net/netns/hash.h
index c06ac58..bcdabe0 100644
--- a/include/net/netns/hash.h
+++ b/include/net/netns/hash.h@@ -1,19 +1,14 @@ #ifndef __NET_NS_HASH_H__ #define __NET_NS_HASH_H__ -#include <asm/cache.h> +#include <linux/hash.h> struct net; static inline unsigned int 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); + return ptr_hash_mix(net); #else return 0; #endif
--
1.7.6.5