bool kill_device(struct device *dev)
{
	/*
	 * Require the device lock and set the "dead" flag to guarantee that
	 * the update behavior is consistent with the other bitfields near
	 * it and that we cannot have an asynchronous probe routine trying
	 * to run while we are tearing out the bus/class/sysfs from
	 * underneath the device.
	 */
	lockdep_assert_held(&dev->mutex);

	if (dev->p->dead)
		return false;
	dev->p->dead = true;
	return true;
}
bool kill_device(struct device *dev)
{
	 
	lockdep_assert_held(&dev->mutex);

	if (dev->p->dead)
		return false;
	dev->p->dead = true;
	return true;
}