Merge branch 'ovs_hash'

Francesco Fusco says:

====================
ovs: introduce arch-specific fast hashing improvements

From: Daniel Borkmann <dborkman@redhat.com>

We are introducing a fast hash function (see patch1) that can be
used in the context of OpenVSwitch to reduce the hashing footprint
(patch2). For details, please see individual patches!

v1->v2:
 - Make hash generic and place it under lib
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 36 insertions, 0 deletions

diff --git a/include/linux/hash.h b/include/linux/hash.h
index f09a0ae4d858..bd1754c7ecef 100644
--- a/include/linux/hash.h
+++ b/include/linux/hash.h
@@ -15,6 +15,7 @@
  */
 
 #include <asm/types.h>
+#include <asm/hash.h>
 #include <linux/compiler.h>
 
 /* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
@@ -78,4 +79,39 @@ static inline u32 hash32_ptr(const void *ptr)
 #endif
 	return (u32)val;
 }
+
+struct fast_hash_ops {
+	u32 (*hash)(const void *data, u32 len, u32 seed);
+	u32 (*hash2)(const u32 *data, u32 len, u32 seed);
+};
+
+/**
+ *	arch_fast_hash - Caclulates a hash over a given buffer that can have
+ *			 arbitrary size. This function will eventually use an
+ *			 architecture-optimized hashing implementation if
+ *			 available, and trades off distribution for speed.
+ *
+ *	@data: buffer to hash
+ *	@len: length of buffer in bytes
+ *	@seed: start seed
+ *
+ *	Returns 32bit hash.
+ */
+extern u32 arch_fast_hash(const void *data, u32 len, u32 seed);
+
+/**
+ *	arch_fast_hash2 - Caclulates a hash over a given buffer that has a
+ *			  size that is of a multiple of 32bit words. This
+ *			  function will eventually use an architecture-
+ *			  optimized hashing implementation if available,
+ *			  and trades off distribution for speed.
+ *
+ *	@data: buffer to hash (must be 32bit padded)
+ *	@len: number of 32bit words
+ *	@seed: start seed
+ *
+ *	Returns 32bit hash.
+ */
+extern u32 arch_fast_hash2(const u32 *data, u32 len, u32 seed);
+
 #endif /* _LINUX_HASH_H */