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>
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 26336cd..bb619d8 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -29,6 +29,7 @@
#include <net/inet_sock.h>
#include <net/sock.h>
#include <net/tcp_states.h>
+#include <net/netns/hash.h>
#include <asm/atomic.h>
#include <asm/byteorder.h>
@@ -204,7 +205,7 @@
static inline int inet_bhashfn(struct net *net,
const __u16 lport, const int bhash_size)
{
- return lport & (bhash_size - 1);
+ return (lport + net_hash_mix(net)) & (bhash_size - 1);
}
extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
@@ -213,7 +214,7 @@
/* These can have wildcards, don't try too hard. */
static inline int inet_lhashfn(struct net *net, const unsigned short num)
{
- return num & (INET_LHTABLE_SIZE - 1);
+ return (num + net_hash_mix(net)) & (INET_LHTABLE_SIZE - 1);
}
static inline int inet_sk_listen_hashfn(const struct sock *sk)