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Commit 3f9120b0 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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driver core: prevent deferred probe with platform_driver_probe 



Prevent drivers relying on platform_driver_probe from requesting
deferred probing in order to avoid further futile probe attempts (either
the driver has been unregistered or its probe function has been set to
platform_drv_probe_fail when probing is retried).

Note that several platform drivers currently return subsystem errors
from probe and that these can include -EPROBE_DEFER (e.g. if a gpio
request fails).

Add a warning to platform_drv_probe that can be used to catch drivers
that inadvertently request probe deferral while using
platform_driver_probe.

Signed-off-by: default avatarJohan Hovold <jhovold@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent eee03164

drivers/base/platform.c

+13 −4
Original line number Diff line number Diff line
@@ -488,6 +488,11 @@ static int platform_drv_probe(struct device *_dev) 
	if (ret && ACPI_HANDLE(_dev))

		acpi_dev_pm_detach(_dev, true);



	if (drv->prevent_deferred_probe && ret == -EPROBE_DEFER) {

		dev_warn(_dev, "probe deferral not supported\n");

		ret = -ENXIO;

	}



	return ret;

}
@@ -553,8 +558,7 @@ EXPORT_SYMBOL_GPL(platform_driver_unregister); 
/**

 * platform_driver_probe - register driver for non-hotpluggable device

 * @drv: platform driver structure

 * @probe: the driver probe routine, probably from an __init section,

 *         must not return -EPROBE_DEFER.

 * @probe: the driver probe routine, probably from an __init section

 *

 * Use this instead of platform_driver_register() when you know the device

 * is not hotpluggable and has already been registered, and you want to
@@ -565,8 +569,7 @@ EXPORT_SYMBOL_GPL(platform_driver_unregister); 
 * into system-on-chip processors, where the controller devices have been

 * configured as part of board setup.

 *

 * This is incompatible with deferred probing so probe() must not

 * return -EPROBE_DEFER.

 * Note that this is incompatible with deferred probing.

 *

 * Returns zero if the driver registered and bound to a device, else returns

 * a negative error code and with the driver not registered.
@@ -576,6 +579,12 @@ int __init_or_module platform_driver_probe(struct platform_driver *drv, 
{

	int retval, code;



	/*

	 * Prevent driver from requesting probe deferral to avoid further

	 * futile probe attempts.

	 */

	drv->prevent_deferred_probe = true;



	/* make sure driver won't have bind/unbind attributes */

	drv->driver.suppress_bind_attrs = true;

include/linux/platform_device.h

+1 −0
Original line number Diff line number Diff line
@@ -178,6 +178,7 @@ struct platform_driver { 
	int (*resume)(struct platform_device *);

	struct device_driver driver;

	const struct platform_device_id *id_table;

	bool prevent_deferred_probe;

};



#define to_platform_driver(drv)	(container_of((drv), struct platform_driver, \