ip_mtu_from_fib_result  518 include/net/ip_fib.h u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr);
ip_mtu_from_fib_result 4689 net/core/filter.c 		mtu = ip_mtu_from_fib_result(&res, params->ipv4_dst);