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authorPavel Machek <pavel@ucw.cz>2019-04-29 17:22:59 +0200
committerJacek Anaszewski <jacek.anaszewski@gmail.com>2019-05-02 22:54:51 +0200
commit0db37915d912e8dc6588f25da76d3ed36718d92f (patch)
tree38722b37751981f868085562a6426b3d222abb4c
parentALSA: line6: Avoid polluting led_* namespace (diff)
downloadlinux-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>
-rw-r--r--drivers/leds/led-class.c1
-rw-r--r--drivers/leds/led-core.c5
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))