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ipv6: add ipv6_addr_hash() helper

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Introduce ipv6_addr_hash() helper doing a XOR on all bits
of an IPv6 address, with an optimized x86_64 version.

Use it in flow dissector, as suggested by Andrew McGregor,
to reduce hash collision probabilities in fq_codel (and other
users of flow dissector)

Use it in ip6_tunnel.c and use more bit shuffling, as suggested
by David Laight, as existing hash was ignoring most of them.

Use it in sunrpc and use more bit shuffling, using hash_32().

Use it in net/ipv6/addrconf.c, using hash_32() as well.

As a cleanup, use it in net/ipv4/tcp_metrics.c

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrew McGregor <andrewmcgr@gmail.com>
Cc: Dave Taht <dave.taht@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2012-07-18 08:11:12 +00:00 • committed by David S. Miller
parent dc9059512c
commit ddbe503203
7 changed files with 45 additions and 54 deletions
Download patch file Download diff file Expand all files Collapse all files

22
net/sunrpc/svcauth_unix.c
View file

@ -104,23 +104,9 @@ static void ip_map_put(struct kref *kref)
kfree(im);
}
#if IP_HASHBITS == 8
/* hash_long on a 64 bit machine is currently REALLY BAD for
* IP addresses in reverse-endian (i.e. on a little-endian machine).
* So use a trivial but reliable hash instead
*/
static inline int hash_ip(__be32 ip)
static inline int hash_ip6(const struct in6_addr *ip)
{
int hash = (__force u32)ip ^ ((__force u32)ip>>16);
return (hash ^ (hash>>8)) & 0xff;
}
#endif
static inline int hash_ip6(struct in6_addr ip)
{
return (hash_ip(ip.s6_addr32[0]) ^
hash_ip(ip.s6_addr32[1]) ^
hash_ip(ip.s6_addr32[2]) ^
hash_ip(ip.s6_addr32[3]));
return hash_32(ipv6_addr_hash(ip), IP_HASHBITS);
}
static int ip_map_match(struct cache_head *corig, struct cache_head *cnew)
{
@ -301,7 +287,7 @@ static struct ip_map *__ip_map_lookup(struct cache_detail *cd, char *class,
ip.m_addr = *addr;
ch = sunrpc_cache_lookup(cd, &ip.h,
hash_str(class, IP_HASHBITS) ^
hash_ip6(*addr));
hash_ip6(addr));
if (ch)
return container_of(ch, struct ip_map, h);
@ -331,7 +317,7 @@ static int __ip_map_update(struct cache_detail *cd, struct ip_map *ipm,
ip.h.expiry_time = expiry;
ch = sunrpc_cache_update(cd, &ip.h, &ipm->h,
hash_str(ipm->m_class, IP_HASHBITS) ^
hash_ip6(ipm->m_addr));
hash_ip6(&ipm->m_addr));
if (!ch)
return -ENOMEM;
cache_put(ch, cd);