xfrm: optimize ipv4 selector matching

Current addr_match() is errh, under-optimized.

Compiler doesn't know that memcmp() branch doesn't trigger for IPv4.
Also, pass addresses by value -- they fit into register.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index b203e14d26b7..4de7ed9016d9 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -827,6 +827,14 @@ static inline bool addr_match(const void *token1, const void *token2,
         return true;
 }
 
+static inline bool addr4_match(__be32 a1, __be32 a2, u8 prefixlen)
+{
+        /* C99 6.5.7 (3): u32 << 32 is undefined behaviour */
+        if (prefixlen == 0)
+                return true;
+        return !((a1 ^ a2) & htonl(0xFFFFFFFFu << (32 - prefixlen)));
+}
+
 static __inline__
 __be16 xfrm_flowi_sport(const struct flowi *fl, const union flowi_uli *uli)
 {