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Commit eb1610b4 authored by Hans de Goede's avatar Hans de Goede Committed by Jacek Anaszewski
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led: core: Fix blink_brightness setting race 



All 3 of led_timer_func, led_set_brightness and led_set_software_blink
set blink_brightness. If led_timer_func or led_set_software_blink race
with led_set_brightness they may end up overwriting the new
blink_brightness. The new atomic work_flags does not protect against
this as it just protects the flags and not blink_brightness.

This commit introduces a new new_blink_brightness value which gets
set by led_set_brightness and read by led_timer_func on LED on, fixing
this.

Dealing with the new brightness at LED on time, makes the new
brightness apply sooner, which also fixes a led_set_brightness which
happens while a oneshot blink which ends in LED on is running not
getting applied.

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarJacek Anaszewski <j.anaszewski@samsung.com>
parent a9c6ce57

drivers/leds/led-core.c

+7 −7
Original line number Original line Diff line number Diff line
@@ -66,16 +66,16 @@ static void led_timer_function(unsigned long data) 
	brightness = led_get_brightness(led_cdev);

	brightness = led_get_brightness(led_cdev);

	if (!brightness) {

	if (!brightness) {

		/* Time to switch the LED on. */

		/* Time to switch the LED on. */

		if (test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE,

					&led_cdev->work_flags))

			brightness = led_cdev->new_blink_brightness;

		else

			brightness = led_cdev->blink_brightness;

			brightness = led_cdev->blink_brightness;

		delay = led_cdev->blink_delay_on;

		delay = led_cdev->blink_delay_on;

	} else {

	} else {

		/* Store the current brightness value to be able

		/* Store the current brightness value to be able

		 * to restore it when the delay_off period is over.

		 * to restore it when the delay_off period is over.

		 * Do it only if there is no pending blink brightness

		 * change, to avoid overwriting the new value.

		 */

		 */

		if (!test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE,

					&led_cdev->work_flags))

		led_cdev->blink_brightness = brightness;

		led_cdev->blink_brightness = brightness;

		brightness = LED_OFF;

		brightness = LED_OFF;

		delay = led_cdev->blink_delay_off;

		delay = led_cdev->blink_delay_off;
@@ -245,7 +245,7 @@ void led_set_brightness(struct led_classdev *led_cdev, 
		} else {

		} else {

			set_bit(LED_BLINK_BRIGHTNESS_CHANGE,

			set_bit(LED_BLINK_BRIGHTNESS_CHANGE,

				&led_cdev->work_flags);

				&led_cdev->work_flags);

			led_cdev->blink_brightness = brightness;

			led_cdev->new_blink_brightness = brightness;

		}

		}

		return;

		return;

	}

	}

include/linux/leds.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -93,6 +93,7 @@ struct led_classdev { 
	unsigned long		 blink_delay_on, blink_delay_off;

	unsigned long		 blink_delay_on, blink_delay_off;

	struct timer_list	 blink_timer;

	struct timer_list	 blink_timer;

	int			 blink_brightness;

	int			 blink_brightness;

	int			 new_blink_brightness;

	void			(*flash_resume)(struct led_classdev *led_cdev);

	void			(*flash_resume)(struct led_classdev *led_cdev);





	struct work_struct	set_brightness_work;

	struct work_struct	set_brightness_work;