linux-kernel - Re: [PATCH] hwmon: (adt7470) Fix warning on module removal

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Date:   Fri, 8 Apr 2022 08:38:35 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Armin Wolf <W_Armin@....de>
Cc:     zheyuma97@...il.com, jdelvare@...e.com,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (adt7470) Fix warning on module removal

On Thu, Apr 07, 2022 at 12:13:12PM +0200, Armin Wolf wrote:
> When removing the adt7470 module, a warning might be printed:
> 
> do not call blocking ops when !TASK_RUNNING; state=1
> set at [<ffffffffa006052b>] adt7470_update_thread+0x7b/0x130 [adt7470]
> 
> This happens because adt7470_update_thread() can leave the kthread in
> TASK_INTERRUPTIBLE state when the kthread is being stopped before
> the call of set_current_state(). Since kthread_exit() might sleep in
> exit_signals(), the warning is printed.
> Fix that by using schedule_timeout_interruptible() and removing
> the call of set_current_state().
> This causes TASK_INTERRUPTIBLE to be set after kthread_should_stop()
> which might cause the kthread to exit.
> 
> Compile-tested only.
> 
> Reported-by: Zheyu Ma <zheyuma97@...il.com>
> Fixes: 93cacfd41f82 (hwmon: (adt7470) Allow faster removal)
> Signed-off-by: Armin Wolf <W_Armin@....de>
> Tested-by: Zheyu Ma <zheyuma97@...il.com>

Applied.

Thanks,
Guenter

> ---
>  drivers/hwmon/adt7470.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --
> 2.30.2
> 
> diff --git a/drivers/hwmon/adt7470.c b/drivers/hwmon/adt7470.c
> index fb6d14d213a1..c67cd037a93f 100644
> --- a/drivers/hwmon/adt7470.c
> +++ b/drivers/hwmon/adt7470.c
> @@ -19,6 +19,7 @@
>  #include <linux/log2.h>
>  #include <linux/kthread.h>
>  #include <linux/regmap.h>
> +#include <linux/sched.h>
>  #include <linux/slab.h>
>  #include <linux/util_macros.h>
> 
> @@ -294,11 +295,10 @@ static int adt7470_update_thread(void *p)
>  		adt7470_read_temperatures(data);
>  		mutex_unlock(&data->lock);
> 
> -		set_current_state(TASK_INTERRUPTIBLE);
>  		if (kthread_should_stop())
>  			break;
> 
> -		schedule_timeout(msecs_to_jiffies(data->auto_update_interval));
> +		schedule_timeout_interruptible(msecs_to_jiffies(data->auto_update_interval));
>  	}
> 
>  	return 0;