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>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index f2b801c4b55..089a09d001d 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -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);