linux-kernel - Re: [PATCH] led/ledtrig-heartbeat: Convert timers to use

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Date:   Fri, 6 Oct 2017 22:18:47 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Cc:     Richard Purdie <rpurdie@...ys.net>, Pavel Machek <pavel@....cz>,
        Zhang Bo <bo.zhang@....com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Ingo Molnar <mingo@...nel.org>, linux-leds@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] led/ledtrig-heartbeat: Convert timers to use

Hi Kees,

Thanks for the patch.

On 10/05/2017 02:49 AM, Kees Cook wrote:
> Instead of using .data directly, convert to from_timer. Since the
> trigger_data is allocated separately, the led_cdev must be explicitly
> tracked for the callback.
> 
> Cc: Richard Purdie <rpurdie@...ys.net>
> Cc: Jacek Anaszewski <jacek.anaszewski@...il.com>
> Cc: Pavel Machek <pavel@....cz>
> Cc: Zhang Bo <bo.zhang@....com>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: linux-leds@...r.kernel.org
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
> This requires commit 686fef928bba ("timer: Prepare to change timer
> callback argument type") in v4.14-rc3, but should be otherwise
> stand-alone.
> ---
>  drivers/leds/trigger/ledtrig-heartbeat.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/leds/trigger/ledtrig-heartbeat.c b/drivers/leds/trigger/ledtrig-heartbeat.c
> index e95ea65380c8..f0896de410b8 100644
> --- a/drivers/leds/trigger/ledtrig-heartbeat.c
> +++ b/drivers/leds/trigger/ledtrig-heartbeat.c
> @@ -25,19 +25,23 @@
>  static int panic_heartbeats;
>  
>  struct heartbeat_trig_data {
> +	struct led_classdev *led_cdev;
>  	unsigned int phase;
>  	unsigned int period;
>  	struct timer_list timer;
>  	unsigned int invert;
>  };
>  
> -static void led_heartbeat_function(unsigned long data)
> +static void led_heartbeat_function(struct timer_list *t)
>  {
> -	struct led_classdev *led_cdev = (struct led_classdev *) data;
> -	struct heartbeat_trig_data *heartbeat_data = led_cdev->trigger_data;
> +	struct heartbeat_trig_data *heartbeat_data =
> +		from_timer(heartbeat_data, t, timer);
> +	struct led_classdev *led_cdev;
>  	unsigned long brightness = LED_OFF;
>  	unsigned long delay = 0;
>  
> +	led_cdev = heartbeat_data->led_cdev;
> +
>  	if (unlikely(panic_heartbeats)) {
>  		led_set_brightness_nosleep(led_cdev, LED_OFF);
>  		return;
> @@ -127,18 +131,18 @@ static void heartbeat_trig_activate(struct led_classdev *led_cdev)
>  		return;
>  
>  	led_cdev->trigger_data = heartbeat_data;
> +	heartbeat_data->led_cdev = led_cdev;
>  	rc = device_create_file(led_cdev->dev, &dev_attr_invert);
>  	if (rc) {
>  		kfree(led_cdev->trigger_data);
>  		return;
>  	}
>  
> -	setup_timer(&heartbeat_data->timer,
> -		    led_heartbeat_function, (unsigned long) led_cdev);
> +	timer_setup(&heartbeat_data->timer, led_heartbeat_function, 0);
>  	heartbeat_data->phase = 0;
>  	if (!led_cdev->blink_brightness)
>  		led_cdev->blink_brightness = led_cdev->max_brightness;
> -	led_heartbeat_function(heartbeat_data->timer.data);
> +	led_heartbeat_function(&heartbeat_data->timer);
>  	set_bit(LED_BLINK_SW, &led_cdev->work_flags);
>  	led_cdev->activated = true;
>  }
> 

It seems that the patch title is somewhat incomplete, so I amended
it as follows:

s/to use/to use timer_setup()/

and applied to the for-next branch of linux-leds.git after rebasing
it onto 4.14-rc3.

-- 
Best regards,
Jacek Anaszewski