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leds: core: Fix race condition for software blink

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led_set_brightness() function: Change handling of software blink to
avoid race conditions when stopping blink and setting brightness.

Triggers may call led_set_brightness(LED_OFF),
led_set_brightness(LED_FULL) in quick succession to disable blinking and
turn the LED on. If the delayed work task has not yet disabled blinking
by the time the second call occurs, then the brightness also needs to be
changed in the delayed work task.

Signed-off-by: Craig McQueen <craig@mcqueen.au>
Link: https://patch.msgid.link/20260423113638.2079302-1-craig@mcqueen.au
Signed-off-by: Lee Jones <lee@kernel.org>
This commit is contained in:
Craig McQueen
2026-04-23 21:36:38 +10:00
committed by Lee Jones
parent 6ebff754c4
commit f92135f100
1 changed files with 20 additions and 13 deletions
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33
drivers/leds/led-core.c
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@@ -303,24 +303,31 @@ EXPORT_SYMBOL_GPL(led_stop_software_blink);
void led_set_brightness(struct led_classdev *led_cdev, unsigned int brightness)
{
/*
* If software blink is active, delay brightness setting
* until the next timer tick.
*/
if (test_bit(LED_BLINK_SW, &led_cdev->work_flags)) {
if (brightness) {
/*
* If software blink disable is pending, also queue brightness setting.
* If software blink is active, delay brightness setting
* until the next timer tick.
*/
if (test_bit(LED_SET_BRIGHTNESS, &led_cdev->work_flags) ||
test_bit(LED_BLINK_DISABLE, &led_cdev->work_flags)) {
led_cdev->delayed_set_value = brightness;
set_bit(LED_SET_BRIGHTNESS, &led_cdev->work_flags);
queue_work(led_cdev->wq, &led_cdev->set_brightness_work);
return;
} else if (test_bit(LED_BLINK_SW, &led_cdev->work_flags)) {
led_cdev->new_blink_brightness = brightness;
set_bit(LED_BLINK_BRIGHTNESS_CHANGE, &led_cdev->work_flags);
return;
}
} else 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) {
set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);
queue_work(led_cdev->wq, &led_cdev->set_brightness_work);
} else {
set_bit(LED_BLINK_BRIGHTNESS_CHANGE,
&led_cdev->work_flags);
led_cdev->new_blink_brightness = brightness;
}
set_bit(LED_BLINK_DISABLE, &led_cdev->work_flags);
queue_work(led_cdev->wq, &led_cdev->set_brightness_work);
return;
}