Commit 14b5d6dd authored by Florian Fainelli's avatar Florian Fainelli Committed by Richard Purdie
Browse files

leds: Fix race between LED device uevent and actual attributes creation 



If we were to dynamically register/unregister leds and have udev or other
daemons handle the leds class uevents, we would be notified of the adding of a
new LED and if the daemon immediately tries to open one of the attributes of
the led device, it would fail with a "no such file or directory" error since
this the attributes are not yet created. Fix this by switching attributes to be
class-wide, such that the driver core will register these attributes with
device_add_attrs and then emit the kobject_uevent ADD signal.

Signed-off-by: default avatarFainelli <ffainelli@freebox.fr>
Signed-off-by: default avatarRichard Purdie <rpurdie@linux.intel.com>
parent 0493a4ff

drivers/leds/led-class.c

+8 −32
Original line number Diff line number Diff line
@@ -72,11 +72,14 @@ static ssize_t led_max_brightness_show(struct device *dev, 
	return sprintf(buf, "%u\n", led_cdev->max_brightness);

}



static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store);

static DEVICE_ATTR(max_brightness, 0444, led_max_brightness_show, NULL);

static struct device_attribute led_class_attrs[] = {

	__ATTR(brightness, 0644, led_brightness_show, led_brightness_store),

	__ATTR(max_brightness, 0644, led_max_brightness_show, NULL),

#ifdef CONFIG_LEDS_TRIGGERS

static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);

	__ATTR(trigger, 0644, led_trigger_show, led_trigger_store),

#endif

	__ATTR_NULL,

};



/**

 * led_classdev_suspend - suspend an led_classdev.
@@ -127,18 +130,11 @@ static int led_resume(struct device *dev) 
 */

int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)

{

	int rc;



	led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,

				      "%s", led_cdev->name);

	if (IS_ERR(led_cdev->dev))

		return PTR_ERR(led_cdev->dev);



	/* register the attributes */

	rc = device_create_file(led_cdev->dev, &dev_attr_brightness);

	if (rc)

		goto err_out;



#ifdef CONFIG_LEDS_TRIGGERS

	init_rwsem(&led_cdev->trigger_lock);

#endif
@@ -150,17 +146,9 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev) 
	if (!led_cdev->max_brightness)

		led_cdev->max_brightness = LED_FULL;



	rc = device_create_file(led_cdev->dev, &dev_attr_max_brightness);

	if (rc)

		goto err_out_attr_max;



	led_update_brightness(led_cdev);



#ifdef CONFIG_LEDS_TRIGGERS

	rc = device_create_file(led_cdev->dev, &dev_attr_trigger);

	if (rc)

		goto err_out_led_list;



	led_trigger_set_default(led_cdev);

#endif
@@ -168,18 +156,8 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev) 
			led_cdev->name);



	return 0;



#ifdef CONFIG_LEDS_TRIGGERS

err_out_led_list:

	device_remove_file(led_cdev->dev, &dev_attr_max_brightness);

#endif

err_out_attr_max:

	device_remove_file(led_cdev->dev, &dev_attr_brightness);

	list_del(&led_cdev->node);

err_out:

	device_unregister(led_cdev->dev);

	return rc;

}



EXPORT_SYMBOL_GPL(led_classdev_register);



/**
@@ -190,10 +168,7 @@ EXPORT_SYMBOL_GPL(led_classdev_register); 
 */

void led_classdev_unregister(struct led_classdev *led_cdev)

{

	device_remove_file(led_cdev->dev, &dev_attr_max_brightness);

	device_remove_file(led_cdev->dev, &dev_attr_brightness);

#ifdef CONFIG_LEDS_TRIGGERS

	device_remove_file(led_cdev->dev, &dev_attr_trigger);

	down_write(&led_cdev->trigger_lock);

	if (led_cdev->trigger)

		led_trigger_set(led_cdev, NULL);
@@ -215,6 +190,7 @@ static int __init leds_init(void) 
		return PTR_ERR(leds_class);

	leds_class->suspend = led_suspend;

	leds_class->resume = led_resume;

	leds_class->dev_attrs = led_class_attrs;

	return 0;

}

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