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

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Message-ID: <CAMhUBj=66_snYzC09DxEy8r0EwOQSGeJAtQ37y51SUWXKcWh=w@mail.gmail.com>
Date:   Thu, 7 Apr 2022 18:53:56 +0800
From:   Zheyu Ma <zheyuma97@...il.com>
To:     Armin Wolf <W_Armin@....de>
Cc:     jdelvare@...e.com, linux@...ck-us.net, linux-hwmon@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] hwmon: (adt7470) Fix warning on module removal

On Thu, Apr 7, 2022 at 6:13 PM Armin Wolf <W_Armin@....de> 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>
> ---
>  drivers/hwmon/adt7470.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> 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;
> --
> 2.30.2
>

Tested-by: Zheyu Ma <zheyuma97@...il.com>

Thanks,
Zheyu Ma