linux-kernel - Re: [PATCH v2 2/5] iio:accel:kxcjk-1013: rearrange iio trigger get and register

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Date:   Tue, 24 May 2022 21:49:32 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Dmitry Rokosov <DDRokosov@...rdevices.ru>
Cc:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "jic23@...nel.org" <jic23@...nel.org>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "lorenzo.bianconi83@...il.com" <lorenzo.bianconi83@...il.com>,
        "srinivas.pandruvada@...ux.intel.com" 
        <srinivas.pandruvada@...ux.intel.com>,
        "teodora.baluta@...el.com" <teodora.baluta@...el.com>,
        "narcisaanamaria12@...il.com" <narcisaanamaria12@...il.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        kernel <kernel@...rdevices.ru>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/5] iio:accel:kxcjk-1013: rearrange iio trigger get
 and register

On Tue, May 24, 2022 at 8:14 PM Dmitry Rokosov <DDRokosov@...rdevices.ru> wrote:
>
> IIO trigger interface function iio_trigger_get() should be called after
> iio_trigger_register() (or its devm analogue) strictly, because of
> iio_trigger_get() acquires module refcnt based on the trigger->owner
> pointer, which is initialized inside iio_trigger_register() to
> THIS_MODULE.
> If this call order is wrong, the next iio_trigger_put() (from sysfs
> callback or "delete module" path) will dereference "default" module
> refcnt, which is incorrect behaviour.

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Fixes: c1288b833881 ("iio: accel: kxcjk-1013: Increment ref counter for indio_dev->trig")
> Signed-off-by: Dmitry Rokosov <ddrokosov@...rdevices.ru>
> ---
>  drivers/iio/accel/kxcjk-1013.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c
> index ac74cdcd2bc8..748b35c2f0c3 100644
> --- a/drivers/iio/accel/kxcjk-1013.c
> +++ b/drivers/iio/accel/kxcjk-1013.c
> @@ -1554,12 +1554,12 @@ static int kxcjk1013_probe(struct i2c_client *client,
>
>                 data->dready_trig->ops = &kxcjk1013_trigger_ops;
>                 iio_trigger_set_drvdata(data->dready_trig, indio_dev);
> -               indio_dev->trig = data->dready_trig;
> -               iio_trigger_get(indio_dev->trig);
>                 ret = iio_trigger_register(data->dready_trig);
>                 if (ret)
>                         goto err_poweroff;
>
> +               indio_dev->trig = iio_trigger_get(data->dready_trig);
> +
>                 data->motion_trig->ops = &kxcjk1013_trigger_ops;
>                 iio_trigger_set_drvdata(data->motion_trig, indio_dev);
>                 ret = iio_trigger_register(data->motion_trig);
> --
> 2.36.0



-- 
With Best Regards,
Andy Shevchenko