led: core: Fix blink_brightness setting race (eb1610b4) · Commits · 戴 / test

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:

Hans de Goede <hdegoede@redhat.com> Signed-off-by:

Jacek Anaszewski <j.anaszewski@samsung.com>

drivers/leds/led-core.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -66,16 +66,16 @@ static void led_timer_function(unsigned long data)
		brightness = led_get_brightness(led_cdev);
		if (!brightness) {
		/* 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;
		delay = led_cdev->blink_delay_on;
		} else {
		/* Store the current brightness value to be able
		* 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;
		brightness = LED_OFF;
		delay = led_cdev->blink_delay_off;
		@@ -245,7 +245,7 @@ void led_set_brightness(struct led_classdev *led_cdev,
		} else {
		set_bit(LED_BLINK_BRIGHTNESS_CHANGE,
		&led_cdev->work_flags);
		led_cdev->blink_brightness = brightness;
		led_cdev->new_blink_brightness = brightness;
		}
		return;
		}

include/linux/leds.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -93,6 +93,7 @@ struct led_classdev {
		unsigned long blink_delay_on, blink_delay_off;
		struct timer_list blink_timer;
		int blink_brightness;
		int new_blink_brightness;
		void (flash_resume)(struct led_classdev led_cdev);

		struct work_struct set_brightness_work;

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