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Commit ddbe5032 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarAndrew 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: default avatarDavid S. Miller <davem@davemloft.net>
parent dc905951

include/net/addrconf.h

+2 −1
Original line number Diff line number Diff line
@@ -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);

include/net/ipv6.h

+13 −0
Original line number Diff line number Diff line
@@ -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] |

net/core/flow_dissector.c

+3 −2
Original line number Diff line number Diff line
@@ -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 @@ bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow) 
			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;

	}

net/ipv4/tcp_metrics.c

+3 −12
Original line number Diff line number Diff line
@@ -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;

net/ipv6/addrconf.c

+8 −13
Original line number Diff line number Diff line
@@ -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) {