linux-kernel - Re: [PATCH v2] iio: adc: exynos: do not rely on 'users' counter in ISR

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Message-ID: <20201006193907.GA30199@qmqm.qmqm.pl>
Date:   Tue, 6 Oct 2020 21:39:07 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     dmitry.torokhov@...il.com
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Andrzej Pietrasiewicz <andrzej.p@...labora.com>,
        linux-iio@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] iio: adc: exynos: do not rely on 'users' counter in
 ISR

On Mon, Oct 05, 2020 at 09:12:14PM -0700, dmitry.torokhov@...il.com wrote:
> The order in which 'users' counter is decremented vs calling drivers'
> close() method is implementation specific, and we should not rely on
> it. Let's introduce driver private flag and use it to signal ISR
> to exit when device is being closed.
> 
> This has a side-effect of fixing issue of accessing inut->users
> outside of input->mutex protection.
[...]

Reviewed-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
(after with a fix mentioned below)

> --- a/drivers/iio/adc/exynos_adc.c
> +++ b/drivers/iio/adc/exynos_adc.c
[...]
> @@ -712,6 +715,7 @@ static int exynos_adc_ts_open(struct input_dev *dev)
>  {
>  	struct exynos_adc *info = input_get_drvdata(dev);
>  
> +	WRITE_ONCE(info->ts_enabled, true);
>  	enable_irq(info->tsirq);
>  
>  	return 0;
> @@ -721,6 +725,7 @@ static void exynos_adc_ts_close(struct input_dev *dev)
>  {
>  	struct exynos_adc *info = input_get_drvdata(dev);
>  
> +	WRITE_ONCE(info->ts_enabled, true);
>  	disable_irq(info->tsirq);

Shouldn't 'true' be 'false' here?

Best Regards,
Michał Mirosław