From eb1610b4c273370f491c5e194e5a56e3470d81e8 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Sun, 23 Oct 2016 21:47:26 +0200 Subject: [PATCH] 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: Hans de Goede Signed-off-by: Jacek Anaszewski --- drivers/leds/led-core.c | 14 +++++++------- include/linux/leds.h | 1 + 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index bd6bb4d44f05..ef1360445413 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -66,17 +66,17 @@ static void led_timer_function(unsigned long data) brightness = led_get_brightness(led_cdev); if (!brightness) { /* Time to switch the LED on. */ - brightness = led_cdev->blink_brightness; + 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; + 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; } diff --git a/include/linux/leds.h b/include/linux/leds.h index 21c598b366f8..569cb531094c 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -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; -- 2.20.1