inspect
atomic_store_relaxed(&afuncs->inspect, funcs->inspect);
atomic_store_relaxed(&afuncs->inspect, NULL);
inspect_func = atomic_load_relaxed(&f->inspect);
.inspect = npfa_icmp_conn,
npf_conn_t * (*inspect)(npf_cache_t *, int);
static ndptr inspect(int, char *);
p = inspect(t, token);