linux-kernel - Re: [PATCH v2] leds: core: Flush scheduled work for system suspend

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Message-ID: <a5a931e5-771d-3356-89c2-b0e49f74161c@gmail.com>
Date:   Thu, 2 Jul 2020 22:50:58 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>, pavel@....cz
Cc:     anthony.wong@...onical.com, Dan Murphy <dmurphy@...com>,
        "open list:LED SUBSYSTEM" <linux-leds@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] leds: core: Flush scheduled work for system suspend

Hi Kai-Heng,

Thank you for the update.

On 7/2/20 7:45 AM, Kai-Heng Feng wrote:
> Sometimes LED won't be turned off by LED_CORE_SUSPENDRESUME flag upon
> system suspend.
> 
> led_set_brightness_nopm() uses schedule_work() to set LED brightness.
> However, there's no guarantee that the scheduled work gets executed
> because no one flushes the work.
> 
> So flush the scheduled work to make sure LED gets turned off.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v2:
>   - Use flush_work() instead.
> 
>   drivers/leds/led-class.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index 3363a6551a70..cc3929f858b6 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -173,6 +173,7 @@ void led_classdev_suspend(struct led_classdev *led_cdev)
>   {
>   	led_cdev->flags |= LED_SUSPENDED;
>   	led_set_brightness_nopm(led_cdev, 0);
> +	flush_work(&led_cdev->set_brightness_work);
>   }
>   EXPORT_SYMBOL_GPL(led_classdev_suspend);
>   
> 

Acked-by: Jacek Anaszewski <jacek.anaszewski@...il.com>

Pavel, this needs to go to stable as well, so let's add the tag:

Fixes: 81fe8e5b73e3 ("leds: core: Add led_set_brightness_nosleep{nopm} 
functions")

-- 
Best regards,
Jacek Anaszewski