[BRIDGE]: faster compare for link local addresses

Use logic operations rather than memcmp() to compare destination
address with link local multicast addresses.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 35b94f9..a260679 100644 (file)
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -112,7 +112,11 @@ static int br_handle_local_finish(struct sk_buff *skb)
  */
 static inline int is_link_local(const unsigned char *dest)
 {
-       return memcmp(dest, br_group_address, 5) == 0 && (dest[5] & 0xf0) == 0;
+       const u16 *a = (const u16 *) dest;
+       static const u16 *const b = (const u16 *const ) br_group_address;
+       static const u16 m = __constant_cpu_to_be16(0xfff0);
+
+       return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
 }
 
 /*