Commit 40b3880d authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

driver core: platform: simplify __platform_driver_probe() 

__platform_driver_probe() pokes around in some bus and driver private
lists and locks in a way that is not needed at all.  The code only wants
to know if a device was bound to the driver that was registered, so walk
all devices on the bus to see if there was a match.  If there is not a
match, return an error.  This is the same logic as was originally
present, but just done in a simpler and more obvious way that is not a
layering violation.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230131082459.301603-2-gregkh@linuxfoundation.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b4ce0bf7

drivers/base/platform.c

+15 −11
Original line number Diff line number Diff line
@@ -883,6 +883,13 @@ static int platform_probe_fail(struct platform_device *pdev) 
	return -ENXIO;

}



static int is_bound_to_driver(struct device *dev, void *driver)

{

	if (dev->driver == driver)

		return 1;

	return 0;

}



/**

 * __platform_driver_probe - register driver for non-hotpluggable device

 * @drv: platform driver structure
@@ -936,20 +943,17 @@ int __init_or_module __platform_driver_probe(struct platform_driver *drv, 
	if (retval)

		return retval;



	/*

	 * Fixup that section violation, being paranoid about code scanning

	 * the list of drivers in order to probe new devices.  Check to see

	 * if the probe was successful, and make sure any forced probes of

	 * new devices fail.

	 */

	spin_lock(&drv->driver.bus->p->klist_drivers.k_lock);

	/* Force all new probes of this driver to fail */

	drv->probe = platform_probe_fail;

	if (list_empty(&drv->driver.p->klist_devices.k_list))

		retval = -ENODEV;

	spin_unlock(&drv->driver.bus->p->klist_drivers.k_lock);



	if (retval)

	/* Walk all platform devices and see if any actually bound to this driver.

	 * If not, return an error as the device should have done so by now.

	 */

	if (!bus_for_each_dev(&platform_bus_type, NULL, &drv->driver, is_bound_to_driver)) {

		retval = -ENODEV;

		platform_driver_unregister(drv);

	}



	return retval;

}

EXPORT_SYMBOL_GPL(__platform_driver_probe);