+#ifdef CONFIG_NETFILTER
+extern unsigned int nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
+ unsigned int dataoff, u_int8_t protocol);
+
+extern int ipv6_netfilter_init(void);
+extern void ipv6_netfilter_fini(void);
+#else /* CONFIG_NETFILTER */
+static inline int ipv6_netfilter_init(void) { return 0; }
+static inline void ipv6_netfilter_fini(void) { return; }
+#endif /* CONFIG_NETFILTER */
+