[IPV6] introduce lightweight IPv6 address comparison function.

It is not optimal to use ipv6_addr_cmp() for simple address
comparison, which checks if two addresses are equal.
Based on idea from Dave Craig <dwcraig@qualcomm.com>.
Signed-off-by: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>

include/net/ipv6.h

@@ -296,6 +296,15 @@ static inline void ipv6_addr_set(struct in6_addr *addr,
 }
 #endif
 
+static inline int ipv6_addr_equal(const struct in6_addr *a1,
+				  const struct in6_addr *a2)
+{
+	return (a1->s6_addr32[0] == a2->s6_addr32[0] &&
+		a1->s6_addr32[1] == a2->s6_addr32[1] &&
+		a1->s6_addr32[2] == a2->s6_addr32[2] &&
+		a1->s6_addr32[3] == a2->s6_addr32[3]);
+}
+
 static inline int ipv6_addr_any(const struct in6_addr *a)
 {
 	return ((a->s6_addr32[0] | a->s6_addr32[1] |