const char *dev_driver_string(const struct device *dev)
{
	struct device_driver *drv;

	/* dev->driver can change to NULL underneath us because of unbinding,
	 * so be careful about accessing it.  dev->bus and dev->class should
	 * never change once they are set, so they don't need special care.
	 */
	drv = READ_ONCE(dev->driver);
	return drv ? drv->name :
			(dev->bus ? dev->bus->name :
			(dev->class ? dev->class->name : ""));
}
const char *dev_driver_string(const struct device *dev)
{
	struct device_driver *drv;

	 
	drv = READ_ONCE(dev->driver);
	return drv ? drv->name :
			(dev->bus ? dev->bus->name :
			(dev->class ? dev->class->name : ""));
}