Commit a9c6ce57 authored by Hans de Goede's avatar Hans de Goede Committed by Jacek Anaszewski
Browse files

led: core: Use atomic bit-field for the blink-flags 



All the LED_BLINK* flags are accessed read-modify-write from e.g.
led_set_brightness and led_blink_set_oneshot while both
set_brightness_work and the blink_timer may be running.

If these race then the modify step done by one of them may be lost,
switch the LED_BLINK* flags to a new atomic work_flags bit-field
to avoid this race.

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarJacek Anaszewski <j.anaszewski@samsung.com>
parent 8338eab5

drivers/leds/led-class.c

+1 −0
Original line number Diff line number Diff line
@@ -204,6 +204,7 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev) 
		dev_warn(parent, "Led %s renamed to %s due to name collision",

				led_cdev->name, dev_name(led_cdev->dev));



	led_cdev->work_flags = 0;

#ifdef CONFIG_LEDS_TRIGGERS

	init_rwsem(&led_cdev->trigger_lock);

#endif

drivers/leds/led-core.c

+27 −25
Original line number Diff line number Diff line
@@ -53,12 +53,13 @@ static void led_timer_function(unsigned long data) 


	if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {

		led_set_brightness_nosleep(led_cdev, LED_OFF);

		led_cdev->flags &= ~LED_BLINK_SW;

		clear_bit(LED_BLINK_SW, &led_cdev->work_flags);

		return;

	}



	if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {

		led_cdev->flags &=  ~(LED_BLINK_ONESHOT_STOP | LED_BLINK_SW);

	if (test_and_clear_bit(LED_BLINK_ONESHOT_STOP,

			       &led_cdev->work_flags)) {

		clear_bit(LED_BLINK_SW, &led_cdev->work_flags);

		return;

	}
@@ -73,10 +74,9 @@ static void led_timer_function(unsigned long data) 
		 * Do it only if there is no pending blink brightness

		 * change, to avoid overwriting the new value.

		 */

		if (!(led_cdev->flags & LED_BLINK_BRIGHTNESS_CHANGE))

		if (!test_and_clear_bit(LED_BLINK_BRIGHTNESS_CHANGE,

					&led_cdev->work_flags))

			led_cdev->blink_brightness = brightness;

		else

			led_cdev->flags &= ~LED_BLINK_BRIGHTNESS_CHANGE;

		brightness = LED_OFF;

		delay = led_cdev->blink_delay_off;

	}
@@ -87,13 +87,15 @@ static void led_timer_function(unsigned long data) 
	 * the final blink state so that the led is toggled each delay_on +

	 * delay_off milliseconds in worst case.

	 */

	if (led_cdev->flags & LED_BLINK_ONESHOT) {

		if (led_cdev->flags & LED_BLINK_INVERT) {

	if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags)) {

		if (test_bit(LED_BLINK_INVERT, &led_cdev->work_flags)) {

			if (brightness)

				led_cdev->flags |= LED_BLINK_ONESHOT_STOP;

				set_bit(LED_BLINK_ONESHOT_STOP,

					&led_cdev->work_flags);

		} else {

			if (!brightness)

				led_cdev->flags |= LED_BLINK_ONESHOT_STOP;

				set_bit(LED_BLINK_ONESHOT_STOP,

					&led_cdev->work_flags);

		}

	}
@@ -106,10 +108,9 @@ static void set_brightness_delayed(struct work_struct *ws) 
		container_of(ws, struct led_classdev, set_brightness_work);

	int ret = 0;



	if (led_cdev->flags & LED_BLINK_DISABLE) {

	if (test_and_clear_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) {

		led_cdev->delayed_set_value = LED_OFF;

		led_stop_software_blink(led_cdev);

		led_cdev->flags &= ~LED_BLINK_DISABLE;

	}



	ret = __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
@@ -152,7 +153,7 @@ static void led_set_software_blink(struct led_classdev *led_cdev, 
		return;

	}



	led_cdev->flags |= LED_BLINK_SW;

	set_bit(LED_BLINK_SW, &led_cdev->work_flags);

	mod_timer(&led_cdev->blink_timer, jiffies + 1);

}
@@ -161,7 +162,7 @@ static void led_blink_setup(struct led_classdev *led_cdev, 
		     unsigned long *delay_on,

		     unsigned long *delay_off)

{

	if (!(led_cdev->flags & LED_BLINK_ONESHOT) &&

	if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&

	    led_cdev->blink_set &&

	    !led_cdev->blink_set(led_cdev, delay_on, delay_off))

		return;
@@ -188,8 +189,8 @@ void led_blink_set(struct led_classdev *led_cdev, 
{

	del_timer_sync(&led_cdev->blink_timer);



	led_cdev->flags &= ~LED_BLINK_ONESHOT;

	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;

	clear_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);

	clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);



	led_blink_setup(led_cdev, delay_on, delay_off);

}
@@ -200,17 +201,17 @@ void led_blink_set_oneshot(struct led_classdev *led_cdev, 
			   unsigned long *delay_off,

			   int invert)

{

	if ((led_cdev->flags & LED_BLINK_ONESHOT) &&

	if (test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) &&

	     timer_pending(&led_cdev->blink_timer))

		return;



	led_cdev->flags |= LED_BLINK_ONESHOT;

	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;

	set_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags);

	clear_bit(LED_BLINK_ONESHOT_STOP, &led_cdev->work_flags);



	if (invert)

		led_cdev->flags |= LED_BLINK_INVERT;

		set_bit(LED_BLINK_INVERT, &led_cdev->work_flags);

	else

		led_cdev->flags &= ~LED_BLINK_INVERT;

		clear_bit(LED_BLINK_INVERT, &led_cdev->work_flags);



	led_blink_setup(led_cdev, delay_on, delay_off);

}
@@ -221,7 +222,7 @@ void led_stop_software_blink(struct led_classdev *led_cdev) 
	del_timer_sync(&led_cdev->blink_timer);

	led_cdev->blink_delay_on = 0;

	led_cdev->blink_delay_off = 0;

	led_cdev->flags &= ~LED_BLINK_SW;

	clear_bit(LED_BLINK_SW, &led_cdev->work_flags);

}

EXPORT_SYMBOL_GPL(led_stop_software_blink);
@@ -232,17 +233,18 @@ void led_set_brightness(struct led_classdev *led_cdev, 
	 * If software blink is active, delay brightness setting

	 * until the next timer tick.

	 */

	if (led_cdev->flags & LED_BLINK_SW) {

	if (test_bit(LED_BLINK_SW, &led_cdev->work_flags)) {

		/*

		 * If we need to disable soft blinking delegate this to the

		 * work queue task to avoid problems in case we are called

		 * from hard irq context.

		 */

		if (brightness == LED_OFF) {

			led_cdev->flags |= LED_BLINK_DISABLE;

			set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);

			schedule_work(&led_cdev->set_brightness_work);

		} else {

			led_cdev->flags |= LED_BLINK_BRIGHTNESS_CHANGE;

			set_bit(LED_BLINK_BRIGHTNESS_CHANGE,

				&led_cdev->work_flags);

			led_cdev->blink_brightness = brightness;

		}

		return;

include/linux/leds.h

+14 −10
Original line number Diff line number Diff line
@@ -42,16 +42,20 @@ struct led_classdev { 
#define LED_UNREGISTERING	(1 << 1)

	/* Upper 16 bits reflect control information */

#define LED_CORE_SUSPENDRESUME	(1 << 16)

#define LED_BLINK_SW		(1 << 17)

#define LED_BLINK_ONESHOT	(1 << 18)

#define LED_BLINK_ONESHOT_STOP	(1 << 19)

#define LED_BLINK_INVERT	(1 << 20)

#define LED_BLINK_BRIGHTNESS_CHANGE (1 << 21)

#define LED_BLINK_DISABLE	(1 << 22)

#define LED_SYSFS_DISABLE	(1 << 23)

#define LED_DEV_CAP_FLASH	(1 << 24)

#define LED_HW_PLUGGABLE	(1 << 25)

#define LED_PANIC_INDICATOR	(1 << 26)

#define LED_SYSFS_DISABLE	(1 << 17)

#define LED_DEV_CAP_FLASH	(1 << 18)

#define LED_HW_PLUGGABLE	(1 << 19)

#define LED_PANIC_INDICATOR	(1 << 20)



	/* set_brightness_work / blink_timer flags, atomic, private. */

	unsigned long		work_flags;



#define LED_BLINK_SW			0

#define LED_BLINK_ONESHOT		1

#define LED_BLINK_ONESHOT_STOP		2

#define LED_BLINK_INVERT		3

#define LED_BLINK_BRIGHTNESS_CHANGE 	4

#define LED_BLINK_DISABLE		5



	/* Set LED brightness level

	 * Must not sleep. Use brightness_set_blocking for drivers

CRA Git | Maintained and supported by SUSTech CRA and CCSE