fib6_new_sernum
WRITE_ONCE(fn->fn_sernum, fib6_new_sernum(net));
__fib6_update_sernum_upto_root(rt, fib6_new_sernum(net));
__fib6_update_sernum_upto_root(rt, fib6_new_sernum(info->nl_net));
int new_sernum = fib6_new_sernum(net);