[PATCH v2] leds: core: avoid error message when a USB LED device is unplugged

[PATCH v2] leds: core: avoid error message when a USB LED device is unplugged

[Heiner Kallweit]

When a USB LED device is unplugged the remove call chain calls
led_classdev_unregister which tries to switch the LED off.
As the device has been removed already this results in a ENODEV
error message in dmesg.
Avoid this error message by ignoring ENODEV in calls from
led_classdev_unregister if the LED device is flagged as pluggable.

Therefore a new flag LED_HW_PLUGGABLE was introduced which should be set by
all LED drivers handling pluggable LED devices (mainly USB LED devices).

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- rebased
---
 drivers/leds/led-class.c | 2 ++
 drivers/leds/led-core.c  | 5 ++++-
 include/linux/leds.h     | 2 ++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 14139c3..aa84e5b 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -245,6 +245,8 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
 	up_write(&led_cdev->trigger_lock);
 #endif
 
+	led_cdev->flags |= LED_UNREGISTERING;
+
 	/* Stop blinking */
 	led_stop_software_blink(led_cdev);
 
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 19e1e60..ad684b6 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -98,7 +98,10 @@ static void set_brightness_delayed(struct work_struct *ws)
 						led_cdev->delayed_set_value);
 	else
 		ret = -ENOTSUPP;
-	if (ret < 0)
+	if (ret < 0 &&
+	    /* LED HW might have been unplugged, therefore don't warn */
+	    !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
+	    (led_cdev->flags & LED_HW_PLUGGABLE)))
 		dev_err(led_cdev->dev,
 			"Setting an LED's brightness failed (%d)\n", ret);
 }
diff --git a/include/linux/leds.h b/include/linux/leds.h
index e3470e7..f203a8f 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -39,6 +39,7 @@ struct led_classdev {
 
 	/* Lower 16 bits reflect status */
 #define LED_SUSPENDED		(1 << 0)
+#define LED_UNREGISTERING	(1 << 1)
 	/* Upper 16 bits reflect control information */
 #define LED_CORE_SUSPENDRESUME	(1 << 16)
 #define LED_BLINK_ONESHOT	(1 << 17)
@@ -48,6 +49,7 @@ struct led_classdev {
 #define LED_BLINK_DISABLE	(1 << 21)
 #define LED_SYSFS_DISABLE	(1 << 22)
 #define LED_DEV_CAP_FLASH	(1 << 23)
+#define LED_HW_PLUGGABLE	(1 << 24)
 
 	/* Set LED brightness level
 	 * Must not sleep. Use brightness_set_blocking for drivers
-- 
2.7.0

Re: [PATCH v2] leds: core: avoid error message when a USB LED device is unplugged

[Jacek Anaszewski]

On 01/22/2016 09:43 PM, Heiner Kallweit wrote:
> When a USB LED device is unplugged the remove call chain calls
> led_classdev_unregister which tries to switch the LED off.
> As the device has been removed already this results in a ENODEV
> error message in dmesg.
> Avoid this error message by ignoring ENODEV in calls from
> led_classdev_unregister if the LED device is flagged as pluggable.
>
> Therefore a new flag LED_HW_PLUGGABLE was introduced which should be set by
> all LED drivers handling pluggable LED devices (mainly USB LED devices).
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> v2:
> - rebased
> ---
>   drivers/leds/led-class.c | 2 ++
>   drivers/leds/led-core.c  | 5 ++++-
>   include/linux/leds.h     | 2 ++
>   3 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 14139c3..aa84e5b 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -245,6 +245,8 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
>   	up_write(&led_cdev->trigger_lock);
>   #endif
>
> +	led_cdev->flags |= LED_UNREGISTERING;
> +
>   	/* Stop blinking */
>   	led_stop_software_blink(led_cdev);
>
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index 19e1e60..ad684b6 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -98,7 +98,10 @@ static void set_brightness_delayed(struct work_struct *ws)
>   						led_cdev->delayed_set_value);
>   	else
>   		ret = -ENOTSUPP;
> -	if (ret < 0)
> +	if (ret < 0 &&
> +	    /* LED HW might have been unplugged, therefore don't warn */
> +	    !(ret == -ENODEV && (led_cdev->flags & LED_UNREGISTERING) &&
> +	    (led_cdev->flags & LED_HW_PLUGGABLE)))
>   		dev_err(led_cdev->dev,
>   			"Setting an LED's brightness failed (%d)\n", ret);
>   }
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index e3470e7..f203a8f 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -39,6 +39,7 @@ struct led_classdev {
>
>   	/* Lower 16 bits reflect status */
>   #define LED_SUSPENDED		(1 << 0)
> +#define LED_UNREGISTERING	(1 << 1)
>   	/* Upper 16 bits reflect control information */
>   #define LED_CORE_SUSPENDRESUME	(1 << 16)
>   #define LED_BLINK_ONESHOT	(1 << 17)
> @@ -48,6 +49,7 @@ struct led_classdev {
>   #define LED_BLINK_DISABLE	(1 << 21)
>   #define LED_SYSFS_DISABLE	(1 << 22)
>   #define LED_DEV_CAP_FLASH	(1 << 23)
> +#define LED_HW_PLUGGABLE	(1 << 24)
>
>   	/* Set LED brightness level
>   	 * Must not sleep. Use brightness_set_blocking for drivers
>

Applied to devel branch, thanks.

-- 
Best Regards,
Jacek Anaszewski