static noinline void ep_destroy_wakeup_source(struct epitem *epi)
{
	struct wakeup_source *ws = ep_wakeup_source(epi);

	RCU_INIT_POINTER(epi->ws, NULL);

	/*
	 * wait for ep_pm_stay_awake_rcu to finish, synchronize_rcu is
	 * used internally by wakeup_source_remove, too (called by
	 * wakeup_source_unregister), so we cannot use call_rcu
	 */
	synchronize_rcu();
	wakeup_source_unregister(ws);
}
static noinline void ep_destroy_wakeup_source(struct epitem *epi)
{
	struct wakeup_source *ws = ep_wakeup_source(epi);

	RCU_INIT_POINTER(epi->ws, NULL);

	 
	synchronize_rcu();
	wakeup_source_unregister(ws);
}