linux-kernel - Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is suspended

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Message-ID: <20160321121736.GH8413@pali>
Date:	Mon, 21 Mar 2016 13:17:36 +0100
From:	Pali Rohár <pali.rohar@...il.com>
To:	Gabriele Mazzotta <gabriele.mzt@...il.com>
Cc:	dvhart@...radead.org, Jared_Dominguez@...l.com,
	platform-driver-x86@...r.kernel.org, rjw@...ysocki.net,
	alex.hung@...onical.com, arvidjaar@...il.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] dell-rbtn: Ignore ACPI notifications if device is
 suspended

On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote:
> +#ifdef CONFIG_PM_SLEEP
> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context)
> +{
> +	struct rbtn_data *rbtn_data = context;
> +
> +	rbtn_data->suspended = false;
> +}
> +
> +static int rbtn_suspend(struct device *dev)
> +{
> +	struct acpi_device *device = to_acpi_device(dev);
> +	struct rbtn_data *rbtn_data = acpi_driver_data(device);
> +
> +	rbtn_data->suspended = true;
> +
> +	return 0;
> +}
> +
> +static int rbtn_resume(struct device *dev)
> +{
> +	struct acpi_device *device = to_acpi_device(dev);
> +	struct rbtn_data *rbtn_data = acpi_driver_data(device);
> +	acpi_status status;
> +
> +	/*
> +	 * Clear the flag only after we received the extra
> +	 * ACPI notification.
> +	 */
> +	status = acpi_os_execute(OSL_NOTIFY_HANDLER,
> +			 rbtn_acpi_clear_flag, rbtn_data);
> +	if (ACPI_FAILURE(status))
> +		rbtn_data->suspended = false;

I case when acpi_os_execute success it calls rbtn_acpi_clear_flag,
right? And that will set suspended to false. When acpi_os_execute fails,
then it set suspended too to false... Then whole acpi_os_execute doing
just "barrier" after which suspended flag can be set to false. So I
think rbtn_acpi_clear_flag function is not needed here.

Cannot you pass NULL or empty function pointer as callback? Or what was
reason to do that flag clearing at "two places"?

> +	return 0;
> +}
> +#endif

-- 
Pali Rohár
pali.rohar@...il.com