ipv6 address comparison

Hi, My module uses ipv6_addr_cmp() from <linux/ipv6.h>. <linux/ipv6.h> static inline int ipv6_addr_cmp(const struct in6_addr *a1, const struct in6_addr *a2) { return memcmp(a1, a2, sizeof(struct in6_addr)); } I've included <linux/ipv6.h>. But when i try to build the module i get following error: net/netfilter/xt_ipaddr.c:81: error: implicit declaration of function ‘ipv6_addr_cmp’ Although before the call to ipv6_addr_cmp, i have a casting to struct ipv6hdr *iph. So the definitions from ipv6.h should be available to my module. cheers. aft