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ipv6: add ipv6_addr_hash() helper 

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/net/addrconf.h
View File

@ -46,7 +46,8 @@ struct prefix_info {
#include <net/if_inet6.h>
#include <net/ipv6.h>
#define IN6_ADDR_HSIZE 16
#define IN6_ADDR_HSIZE_SHIFT 4
#define IN6_ADDR_HSIZE (1 << IN6_ADDR_HSIZE_SHIFT)
extern int addrconf_init(void);
extern void addrconf_cleanup(void);

13
include/net/ipv6.h
View File

@ -419,6 +419,19 @@ static inline bool ipv6_addr_any(const struct in6_addr *a)
#endif
}
static inline u32 ipv6_addr_hash(const struct in6_addr *a)
{
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
const unsigned long *ul = (const unsigned long *)a;
unsigned long x = ul[0] ^ ul[1];
return (u32)(x ^ (x >> 32));
#else
return (__force u32)(a->s6_addr32[0] ^ a->s6_addr32[1] ^
a->s6_addr32[2] ^ a->s6_addr32[3]);
#endif
}
static inline bool ipv6_addr_loopback(const struct in6_addr *a)
{
return (a->s6_addr32[0] | a->s6_addr32[1] |

5
net/core/flow_dissector.c
View File

@ -4,6 +4,7 @@
#include <linux/ipv6.h>
#include <linux/if_vlan.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <linux/if_tunnel.h>
#include <linux/if_pppox.h>
#include <linux/ppp_defs.h>
@ -55,8 +56,8 @@ ipv6:
return false;
ip_proto = iph->nexthdr;
flow->src = iph->saddr.s6_addr32[3];
flow->dst = iph->daddr.s6_addr32[3];
flow->src = (__force __be32)ipv6_addr_hash(&iph->saddr);
flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr);
nhoff += sizeof(struct ipv6hdr);
break;
}

15
net/ipv4/tcp_metrics.c
View File

@ -211,10 +211,7 @@ static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
break;
case AF_INET6:
*(struct in6_addr *)addr.addr.a6 = inet6_rsk(req)->rmt_addr;
hash = ((__force unsigned int) addr.addr.a6[0] ^
(__force unsigned int) addr.addr.a6[1] ^
(__force unsigned int) addr.addr.a6[2] ^
(__force unsigned int) addr.addr.a6[3]);
hash = ipv6_addr_hash(&inet6_rsk(req)->rmt_addr);
break;
default:
return NULL;
@ -251,10 +248,7 @@ static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock
case AF_INET6:
tw6 = inet6_twsk((struct sock *)tw);
*(struct in6_addr *)addr.addr.a6 = tw6->tw_v6_daddr;
hash = ((__force unsigned int) addr.addr.a6[0] ^
(__force unsigned int) addr.addr.a6[1] ^
(__force unsigned int) addr.addr.a6[2] ^
(__force unsigned int) addr.addr.a6[3]);
hash = ipv6_addr_hash(&tw6->tw_v6_daddr);
break;
default:
return NULL;
@ -291,10 +285,7 @@ static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
break;
case AF_INET6:
*(struct in6_addr *)addr.addr.a6 = inet6_sk(sk)->daddr;
hash = ((__force unsigned int) addr.addr.a6[0] ^
(__force unsigned int) addr.addr.a6[1] ^
(__force unsigned int) addr.addr.a6[2] ^
(__force unsigned int) addr.addr.a6[3]);
hash = ipv6_addr_hash(&inet6_sk(sk)->daddr);
break;
default:
return NULL;

21
net/ipv6/addrconf.c
View File

@ -63,6 +63,7 @@
#include <linux/delay.h>
#include <linux/notifier.h>
#include <linux/string.h>
#include <linux/hash.h>
#include <net/net_namespace.h>
#include <net/sock.h>
@ -579,15 +580,9 @@ ipv6_link_dev_addr(struct inet6_dev *idev, struct inet6_ifaddr *ifp)
list_add_tail(&ifp->if_list, p);
}
static u32 ipv6_addr_hash(const struct in6_addr *addr)
static u32 inet6_addr_hash(const struct in6_addr *addr)
{
/*
* We perform the hash function over the last 64 bits of the address
* This will include the IEEE address token on links that support it.
*/
return jhash_2words((__force u32)addr->s6_addr32[2],
(__force u32)addr->s6_addr32[3], 0)
& (IN6_ADDR_HSIZE - 1);
return hash_32(ipv6_addr_hash(addr), IN6_ADDR_HSIZE_SHIFT);
}
/* On success it returns ifp with increased reference count */
@ -662,7 +657,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, int pfxlen,
in6_ifa_hold(ifa);
/* Add to big hash table */
hash = ipv6_addr_hash(addr);
hash = inet6_addr_hash(addr);
hlist_add_head_rcu(&ifa->addr_lst, &inet6_addr_lst[hash]);
spin_unlock(&addrconf_hash_lock);
@ -1270,7 +1265,7 @@ int ipv6_chk_addr(struct net *net, const struct in6_addr *addr,
{
struct inet6_ifaddr *ifp;
struct hlist_node *node;
unsigned int hash = ipv6_addr_hash(addr);
unsigned int hash = inet6_addr_hash(addr);
rcu_read_lock_bh();
hlist_for_each_entry_rcu(ifp, node, &inet6_addr_lst[hash], addr_lst) {
@ -1293,7 +1288,7 @@ EXPORT_SYMBOL(ipv6_chk_addr);
static bool ipv6_chk_same_addr(struct net *net, const struct in6_addr *addr,
struct net_device *dev)
{
unsigned int hash = ipv6_addr_hash(addr);
unsigned int hash = inet6_addr_hash(addr);
struct inet6_ifaddr *ifp;
struct hlist_node *node;
@ -1336,7 +1331,7 @@ struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net, const struct in6_addr *add
struct net_device *dev, int strict)
{
struct inet6_ifaddr *ifp, *result = NULL;
unsigned int hash = ipv6_addr_hash(addr);
unsigned int hash = inet6_addr_hash(addr);
struct hlist_node *node;
rcu_read_lock_bh();
@ -3223,7 +3218,7 @@ int ipv6_chk_home_addr(struct net *net, const struct in6_addr *addr)
int ret = 0;
struct inet6_ifaddr *ifp = NULL;
struct hlist_node *n;
unsigned int hash = ipv6_addr_hash(addr);
unsigned int hash = inet6_addr_hash(addr);
rcu_read_lock_bh();
hlist_for_each_entry_rcu_bh(ifp, n, &inet6_addr_lst[hash], addr_lst) {

20
net/ipv6/ip6_tunnel.c
View File

@ -40,6 +40,7 @@
#include <linux/rtnetlink.h>
#include <linux/netfilter_ipv6.h>
#include <linux/slab.h>
#include <linux/hash.h>
#include <asm/uaccess.h>
#include <linux/atomic.h>
@ -70,11 +71,15 @@ MODULE_ALIAS_NETDEV("ip6tnl0");
#define IPV6_TCLASS_MASK (IPV6_FLOWINFO_MASK & ~IPV6_FLOWLABEL_MASK)
#define IPV6_TCLASS_SHIFT 20
#define HASH_SIZE 32
#define HASH_SIZE_SHIFT 5
#define HASH_SIZE (1 << HASH_SIZE_SHIFT)
#define HASH(addr) ((__force u32)((addr)->s6_addr32[0] ^ (addr)->s6_addr32[1] ^ \
(addr)->s6_addr32[2] ^ (addr)->s6_addr32[3]) & \
(HASH_SIZE - 1))
static u32 HASH(const struct in6_addr *addr1, const struct in6_addr *addr2)
{
u32 hash = ipv6_addr_hash(addr1) ^ ipv6_addr_hash(addr2);
return hash_32(hash, HASH_SIZE_SHIFT);
}
static int ip6_tnl_dev_init(struct net_device *dev);
static void ip6_tnl_dev_setup(struct net_device *dev);
@ -166,12 +171,11 @@ static inline void ip6_tnl_dst_store(struct ip6_tnl *t, struct dst_entry *dst)
static struct ip6_tnl *
ip6_tnl_lookup(struct net *net, const struct in6_addr *remote, const struct in6_addr *local)
{
unsigned int h0 = HASH(remote);
unsigned int h1 = HASH(local);
unsigned int hash = HASH(remote, local);
struct ip6_tnl *t;
struct ip6_tnl_net *ip6n = net_generic(net, ip6_tnl_net_id);
for_each_ip6_tunnel_rcu(ip6n->tnls_r_l[h0 ^ h1]) {
for_each_ip6_tunnel_rcu(ip6n->tnls_r_l[hash]) {
if (ipv6_addr_equal(local, &t->parms.laddr) &&
ipv6_addr_equal(remote, &t->parms.raddr) &&
(t->dev->flags & IFF_UP))
@ -205,7 +209,7 @@ ip6_tnl_bucket(struct ip6_tnl_net *ip6n, const struct ip6_tnl_parm *p)
if (!ipv6_addr_any(remote) || !ipv6_addr_any(local)) {
prio = 1;
h = HASH(remote) ^ HASH(local);
h = HASH(remote, local);
}
return &ip6n->tnls[prio][h];
}

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);