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authorPavel Emelyanov <xemul@openvz.org>2008-06-16 17:14:11 -0700
committerDavid S. Miller <davem@davemloft.net>2008-06-16 17:14:11 -0700
commit0b4419162aa6c4204843f3a13b48d9ab821d3167 (patch)
tree1c475a8f59b7fce528eb97c6709b25145c110c33 /include/net/netns/hash.h
parent33de014c63646f69f36f3673e3b4676f931dc878 (diff)
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>
Diffstat (limited to 'include/net/netns/hash.h')
-rw-r--r--include/net/netns/hash.h21
1 files changed, 21 insertions, 0 deletions
diff --git a/include/net/netns/hash.h b/include/net/netns/hash.h
new file mode 100644
index 00000000000..548d78f2cc4
--- /dev/null
+++ b/include/net/netns/hash.h
@@ -0,0 +1,21 @@
+#ifndef __NET_NS_HASH_H__
+#define __NET_NS_HASH_H__
+
+#include <asm/cache.h>
+
+struct net;
+
+static inline unsigned net_hash_mix(struct net *net)
+{
+#ifdef CONFIG_NET_NS
+ /*
+ * shift this right to eliminate bits, that are
+ * always zeroed
+ */
+
+ return (unsigned)(((unsigned long)net) >> L1_CACHE_SHIFT);
+#else
+ return 0;
+#endif
+}
+#endif