From fa15d8c69238b352cc143cb9d8f2ca4594b94022 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Wed, 10 May 2023 18:22:32 +0200 Subject: leds: Fix set_brightness_delayed() race When a trigger wants to switch from blinking to LED on it needs to call: led_set_brightness(LED_OFF); led_set_brightness(LED_FULL); To first call disables blinking and the second then turns the LED on (the power-supply charging-blink-full-solid triggers do this). These calls happen immediately after each other, so it is possible that set_brightness_delayed() from the first call has not run yet when the led_set_brightness(LED_FULL) call finishes. If this race hits then this is causing problems for both sw- and hw-blinking: For sw-blinking set_brightness_delayed() clears delayed_set_value when LED_BLINK_DISABLE is set causing the led_set_brightness(LED_FULL) call effects to get lost when hitting the race, resulting in the LED turning off instead of on. For hw-blinking if the race hits delayed_set_value has been set to LED_FULL by the time set_brightness_delayed() runs. So led_cdev->brightness_set_blocking() is never called with LED_OFF as argument and the hw-blinking is never disabled leaving the LED blinking instead of on. Fix both issues by adding LED_SET_BRIGHTNESS and LED_SET_BRIGHTNESS_OFF work_flags making this 2 separate actions to be run by set_brightness_delayed(). Signed-off-by: Hans de Goede Reviewed-by: Jacek Anaszewski Tested-by: Yauhen Kharuzhy Link: https://lore.kernel.org/r/20230510162234.291439-3-hdegoede@redhat.com Signed-off-by: Lee Jones --- include/linux/leds.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux') diff --git a/include/linux/leds.h b/include/linux/leds.h index c3dc22d184e2..de813fe96a20 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -124,6 +124,9 @@ struct led_classdev { #define LED_BLINK_INVERT 3 #define LED_BLINK_BRIGHTNESS_CHANGE 4 #define LED_BLINK_DISABLE 5 + /* Brightness off also disables hw-blinking so it is a separate action */ +#define LED_SET_BRIGHTNESS_OFF 6 +#define LED_SET_BRIGHTNESS 7 /* Set LED brightness level * Must not sleep. Use brightness_set_blocking for drivers -- cgit v1.2.3-70-g09d2