linux-kernel - Re: [PATCH v2] iio: adc: mxs-lradc: fix the order of two cleanup operations

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Date:   Sun, 23 Apr 2023 11:40:43 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Jiakai Luo <jkluo@...t.edu.cn>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Lee Jones <lee.jones@...aro.org>, Marek Vasut <marex@...x.de>,
        Ksenija Stanojevic <ksenija.stanojevic@...il.com>,
        hust-os-kernel-patches@...glegroups.com, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: adc: mxs-lradc: fix the order of two cleanup
 operations

On Sat, 22 Apr 2023 06:34:06 -0700
Jiakai Luo <jkluo@...t.edu.cn> wrote:

> Smatch reports:
> drivers/iio/adc/mxs-lradc-adc.c:766 mxs_lradc_adc_probe() warn:
> missing unwind goto?
> 
> the order of three init operation:
> 1.mxs_lradc_adc_trigger_init
> 2.iio_triggered_buffer_setup
> 3.mxs_lradc_adc_hw_init
> 
> thus, the order of three cleanup operation should be:
> 1.mxs_lradc_adc_hw_stop
> 2.iio_triggered_buffer_cleanup
> 3.mxs_lradc_adc_trigger_remove
> 
> we exchange the order of two cleanup operations,
> introducing the following differences:
> 1.if mxs_lradc_adc_trigger_init fails, returns directly;
> 2.if trigger_init succeeds but iio_triggered_buffer_setup fails,
> goto err_trig and remove the trigger.
> 
> In addition, we also reorder the unwind that goes on in the
> remove() callback to match the new ordering.
> 
> Fixes: 6dd112b9f85e ("iio: adc: mxs-lradc: Add support for ADC driver")
> Signed-off-by: Jiakai Luo <jkluo@...t.edu.cn>
> Reviewed-by: Dongliang Mu <dzm91@...t.edu.cn>

Applied to the fixes-togreg branch of iio.git and marked for backporting to
stable. At this stage I'll probably wait until around rc1 to send out a pull
request with this in.  

Thanks,

Jonathan

> ---
> The issue is found by static analysis and remains untested.
> ---
>  drivers/iio/adc/mxs-lradc-adc.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iio/adc/mxs-lradc-adc.c b/drivers/iio/adc/mxs-lradc-adc.c
> index bca79a93cbe4..85882509b7d9 100644
> --- a/drivers/iio/adc/mxs-lradc-adc.c
> +++ b/drivers/iio/adc/mxs-lradc-adc.c
> @@ -757,13 +757,13 @@ static int mxs_lradc_adc_probe(struct platform_device *pdev)
>  
>  	ret = mxs_lradc_adc_trigger_init(iio);
>  	if (ret)
> -		goto err_trig;
> +		return ret;
>  
>  	ret = iio_triggered_buffer_setup(iio, &iio_pollfunc_store_time,
>  					 &mxs_lradc_adc_trigger_handler,
>  					 &mxs_lradc_adc_buffer_ops);
>  	if (ret)
> -		return ret;
> +		goto err_trig;
>  
>  	adc->vref_mv = mxs_lradc_adc_vref_mv[lradc->soc];
>  
> @@ -801,9 +801,9 @@ static int mxs_lradc_adc_probe(struct platform_device *pdev)
>  
>  err_dev:
>  	mxs_lradc_adc_hw_stop(adc);
> -	mxs_lradc_adc_trigger_remove(iio);
> -err_trig:
>  	iio_triggered_buffer_cleanup(iio);
> +err_trig:
> +	mxs_lradc_adc_trigger_remove(iio);
>  	return ret;
>  }
>  
> @@ -814,8 +814,8 @@ static int mxs_lradc_adc_remove(struct platform_device *pdev)
>  
>  	iio_device_unregister(iio);
>  	mxs_lradc_adc_hw_stop(adc);
> -	mxs_lradc_adc_trigger_remove(iio);
>  	iio_triggered_buffer_cleanup(iio);
> +	mxs_lradc_adc_trigger_remove(iio);
> 
>  	return 0;
>  }