linux-kernel - Re: [PATCH v4 4/7] ACPI: button: Use input_device

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Date:   Wed, 24 Jun 2020 22:24:46 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Andrzej Pietrasiewicz <andrzej.p@...labora.com>
Cc:     linux-pm@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-input@...r.kernel.org,
        linux-tegra@...r.kernel.org, patches@...nsource.cirrus.com,
        ibm-acpi-devel@...ts.sourceforge.net,
        platform-driver-x86@...r.kernel.org,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        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>,
        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>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Sylvain Lemieux <slemieux.tyco@...il.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Barry Song <baohua@...nel.org>,
        Michael Hennerich <michael.hennerich@...log.com>,
        Nick Dyer <nick@...anahar.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Ferruh Yigit <fery@...ress.com>,
        Sangwon Jee <jeesw@...fas.com>,
        Peter Hutterer <peter.hutterer@...hat.com>,
        Henrique de Moraes Holschuh <ibm-acpi@....eng.br>,
        kernel@...labora.com
Subject: Re: [PATCH v4 4/7] ACPI: button: Use input_device_enabled() helper

On Mon, Jun 08, 2020 at 01:22:08PM +0200, Andrzej Pietrasiewicz wrote:
> A new helper is available, so use it.
> 
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@...labora.com>
> ---
>  drivers/acpi/button.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/button.c b/drivers/acpi/button.c
> index ff7ab291f678..4deb2b48d03c 100644
> --- a/drivers/acpi/button.c
> +++ b/drivers/acpi/button.c
> @@ -411,7 +411,7 @@ static void acpi_button_notify(struct acpi_device *device, u32 event)
>  		input = button->input;
>  		if (button->type == ACPI_BUTTON_TYPE_LID) {
>  			mutex_lock(&button->input->mutex);
> -			users = button->input->users;
> +			users = input_device_enabled(button->input);
>  			mutex_unlock(&button->input->mutex);
>  			if (users)

This chunk (pre-patch) is really wrong. 'users' value is obsolete and
can not be trusted the moment we unlocked the mutex. "if" needs to be
inside critical section.

>  				acpi_lid_update_state(device, true);
> @@ -460,7 +460,7 @@ static int acpi_button_resume(struct device *dev)
>  
>  	button->suspended = false;
>  	mutex_lock(&input->mutex);
> -	if (button->type == ACPI_BUTTON_TYPE_LID && input->users) {
> +	if (button->type == ACPI_BUTTON_TYPE_LID && input_device_enabled(input)) {
>  		button->last_state = !!acpi_lid_evaluate_state(device);
>  		button->last_time = ktime_get();
>  		acpi_lid_initialize_state(device);
> -- 
> 2.17.1
> 

Thanks.

-- 
Dmitry