CPUHP_AP_IDLE_DEAD
BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
st->state = CPUHP_AP_IDLE_DEAD;
[CPUHP_AP_IDLE_DEAD] = {
return CPUHP_AP_IDLE_DEAD <= state && state < CPUHP_AP_ONLINE;