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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: Fainelli <ffainelli@freebox.fr> Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
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parent
0493a4ff10
commit
14b5d6dd40
1 changed files with 8 additions and 32 deletions
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@ -72,11 +72,14 @@ static ssize_t led_max_brightness_show(struct device *dev,
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return sprintf(buf, "%u\n", led_cdev->max_brightness);
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}
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static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store);
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static DEVICE_ATTR(max_brightness, 0444, led_max_brightness_show, NULL);
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static struct device_attribute led_class_attrs[] = {
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__ATTR(brightness, 0644, led_brightness_show, led_brightness_store),
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__ATTR(max_brightness, 0644, led_max_brightness_show, NULL),
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#ifdef CONFIG_LEDS_TRIGGERS
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static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
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__ATTR(trigger, 0644, led_trigger_show, led_trigger_store),
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#endif
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__ATTR_NULL,
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};
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/**
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* led_classdev_suspend - suspend an led_classdev.
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@ -127,18 +130,11 @@ static int led_resume(struct device *dev)
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*/
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int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
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{
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int rc;
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led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
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"%s", led_cdev->name);
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if (IS_ERR(led_cdev->dev))
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return PTR_ERR(led_cdev->dev);
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/* register the attributes */
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rc = device_create_file(led_cdev->dev, &dev_attr_brightness);
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if (rc)
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goto err_out;
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#ifdef CONFIG_LEDS_TRIGGERS
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init_rwsem(&led_cdev->trigger_lock);
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#endif
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@ -150,17 +146,9 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
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if (!led_cdev->max_brightness)
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led_cdev->max_brightness = LED_FULL;
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rc = device_create_file(led_cdev->dev, &dev_attr_max_brightness);
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if (rc)
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goto err_out_attr_max;
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led_update_brightness(led_cdev);
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#ifdef CONFIG_LEDS_TRIGGERS
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rc = device_create_file(led_cdev->dev, &dev_attr_trigger);
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if (rc)
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goto err_out_led_list;
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led_trigger_set_default(led_cdev);
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#endif
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@ -168,18 +156,8 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
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led_cdev->name);
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return 0;
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#ifdef CONFIG_LEDS_TRIGGERS
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err_out_led_list:
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device_remove_file(led_cdev->dev, &dev_attr_max_brightness);
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#endif
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err_out_attr_max:
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device_remove_file(led_cdev->dev, &dev_attr_brightness);
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list_del(&led_cdev->node);
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err_out:
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device_unregister(led_cdev->dev);
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return rc;
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}
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EXPORT_SYMBOL_GPL(led_classdev_register);
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/**
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@ -190,10 +168,7 @@ EXPORT_SYMBOL_GPL(led_classdev_register);
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*/
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void led_classdev_unregister(struct led_classdev *led_cdev)
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{
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device_remove_file(led_cdev->dev, &dev_attr_max_brightness);
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device_remove_file(led_cdev->dev, &dev_attr_brightness);
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#ifdef CONFIG_LEDS_TRIGGERS
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device_remove_file(led_cdev->dev, &dev_attr_trigger);
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down_write(&led_cdev->trigger_lock);
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if (led_cdev->trigger)
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led_trigger_set(led_cdev, NULL);
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@ -215,6 +190,7 @@ static int __init leds_init(void)
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return PTR_ERR(leds_class);
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leds_class->suspend = led_suspend;
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leds_class->resume = led_resume;
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leds_class->dev_attrs = led_class_attrs;
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return 0;
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}
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