leds: triggers: Flush pending brightness before activating trigger

The race fixed in timer_trig_activate() between a blocking
set_brightness() call and trigger->activate() can affect any trigger.
So move the call to flush_work() into led_trigger_set() where it can
avoid the race for all triggers.

Fixes: 0db37915d912 ("leds: avoid races with workqueue")
Fixes: 8c0f693c6eff ("leds: avoid flush_work in atomic context")
Cc: stable@vger.kernel.org
Tested-by: Dustin L. Howett <dustin@howett.net>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20240613-led-trigger-flush-v2-1-f4f970799d77@weissschuh.net
Signed-off-by: Lee Jones <lee@kernel.org>

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 59deadb8633589b32631d1deb8ae88988d75bbb1..78eb20093b2c10643e26cea3517acf5a58df423d 100644 (file)
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -201,6 +201,12 @@ int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
                 */
                synchronize_rcu();
 
+               /*
+                * If "set brightness to 0" is pending in workqueue,
+                * we don't want that to be reordered after ->activate()
+                */
+               flush_work(&led_cdev->set_brightness_work);
+
                ret = 0;
                if (trig->activate)
                        ret = trig->activate(led_cdev);

diff --git a/drivers/leds/trigger/ledtrig-timer.c b/drivers/leds/trigger/ledtrig-timer.c
index b4688d1d9d2b2455bdca44e1823530f5811961e8..1d213c999d40a51f72a700ee77e79c13fcfe1e84 100644 (file)
--- a/drivers/leds/trigger/ledtrig-timer.c
+++ b/drivers/leds/trigger/ledtrig-timer.c
@@ -110,11 +110,6 @@ static int timer_trig_activate(struct led_classdev *led_cdev)
                led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
        }
 
-       /*
-        * If "set brightness to 0" is pending in workqueue, we don't
-        * want that to be reordered after blink_set()
-        */
-       flush_work(&led_cdev->set_brightness_work);
        led_blink_set(led_cdev, &led_cdev->blink_delay_on,
                      &led_cdev->blink_delay_off);