struct fib6_info *rt6_add_dflt_router(struct net *net,
				     const struct in6_addr *gwaddr,
				     struct net_device *dev, unsigned int pref,
				     u32 defrtr_usr_metric)
struct fib6_info *rt6_add_dflt_router(struct net *net,
				     const struct in6_addr *gwaddr,
				     struct net_device *dev, unsigned int pref,
				     u32 defrtr_usr_metric,
				     int lifetime)