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| author |   Pavel Machek <pavel@ucw.cz> | 2019-04-29 17:22:59 +0200 |
|---|---|---|
| committer |   Jacek Anaszewski <jacek.anaszewski@gmail.com> | 2019-05-02 22:54:51 +0200 |
| commit | 0db37915d912e8dc6588f25da76d3ed36718d92f (patch) | |
| tree | 38722b37751981f868085562a6426b3d222abb4c /drivers/leds | |
| parent | ALSA: line6: Avoid polluting led_* namespace (diff) | |
| download | linux-dev-0db37915d912e8dc6588f25da76d3ed36718d92f.tar.xz linux-dev-0db37915d912e8dc6588f25da76d3ed36718d92f.zip | |
leds: avoid races with workqueue
There are races between "main" thread and workqueue. They manifest
themselves on Thinkpad X60:
This should result in LED blinking, but it turns it off instead:
root@amd:/data/pavel# cd /sys/class/leds/tpacpi\:\:power
root@amd:/sys/class/leds/tpacpi::power# echo timer > trigger
root@amd:/sys/class/leds/tpacpi::power# echo timer > trigger
It should be possible to transition from blinking to solid on by echo
0 > brightness; echo 1 > brightness... but that does not work, either,
if done too quickly.
Synchronization of the workqueue fixes both.
Fixes: 1afcadfcd184 ("leds: core: Use set_brightness_work for the blocking op")
Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Diffstat (limited to 'drivers/leds')
| -rw-r--r-- | drivers/leds/led-class.c | 1 | ||||
| -rw-r--r-- | drivers/leds/led-core.c | 5 |
2 files changed, 6 insertions, 0 deletions
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 3c7e3487b373..85848c5da705 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -57,6 +57,7 @@ static ssize_t brightness_store(struct device *dev, if (state == LED_OFF) led_trigger_remove(led_cdev); led_set_brightness(led_cdev, state); + flush_work(&led_cdev->set_brightness_work); ret = size; unlock: diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c index e3da7c03da1b..e9ae7f87ab90 100644 --- a/drivers/leds/led-core.c +++ b/drivers/leds/led-core.c @@ -164,6 +164,11 @@ static void led_blink_setup(struct led_classdev *led_cdev, unsigned long *delay_on, unsigned long *delay_off) { + /* + * 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); if (!test_bit(LED_BLINK_ONESHOT, &led_cdev->work_flags) && led_cdev->blink_set && !led_cdev->blink_set(led_cdev, delay_on, delay_off)) |