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authorHans de Goede <hdegoede@redhat.com>2016-10-23 21:47:26 +0200
committerJacek Anaszewski <j.anaszewski@samsung.com>2016-11-22 12:07:05 +0100
commiteb1610b4c273370f491c5e194e5a56e3470d81e8 (patch)
treeae3eaaea3b20831c561e6897f936da2f1c7652b5 /drivers/leds/led-core.c
parenta9c6ce57ec2f136d08141e8220a0ffaca216f7b0 (diff)
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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 <hdegoede@redhat.com> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Diffstat (limited to 'drivers/leds/led-core.c')
-rw-r--r--drivers/leds/led-core.c14
1 files changed, 7 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;
}