netns: introduce the net_hash_mix "salt" for hashes

There are many possible ways to add this "salt", thus I made this
patch to be the last in the series to change it if required.

Currently I propose to use the struct net pointer itself as this 
salt, but since this pointer is most often cache-line aligned, shift 
this right to eliminate the bits, that are most often zeroed.

After this, simply add this mix to prepared hashfn-s.

For CONFIG_NET_NS=n case this salt is 0 and no changes in hashfn
appear.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
index 72f13a9928e4..e48989f04c24 100644
--- a/include/net/inet6_hashtables.h
+++ b/include/net/inet6_hashtables.h
@@ -24,6 +24,7 @@
 #include <net/inet_sock.h>
 
 #include <net/ipv6.h>
+#include <net/netns/hash.h>
 
 struct inet_hashinfo;
 
@@ -36,7 +37,7 @@ static inline unsigned int inet6_ehashfn(struct net *net,
 
         return jhash_3words((__force u32)laddr->s6_addr32[3],
                             (__force u32)faddr->s6_addr32[3],
-                            ports, inet_ehash_secret);
+                            ports, inet_ehash_secret + net_hash_mix(net));
 }
 
 static inline int inet6_sk_ehashfn(const struct sock *sk)