Re: [PATCH 09/12] platform/x86: wmi: create character devices when requested by drivers

From: Andy Shevchenko
Date: Thu Sep 21 2017 - 12:46:37 EST

On Thu, Sep 21, 2017 at 4:57 PM, Mario Limonciello
<mario.limonciello@xxxxxxxx> wrote:
> For WMI operations that are only Set or Query read or write sysfs
> attributes created by WMI vendor drivers make sense.
> For other WMI operations that are run on Method, there needs to be a
> way to guarantee to userspace that the results from the method call
> belong to the data request to the method call. Sysfs attributes don't
> work well in this scenario because two userspace processes may be
> competing at reading/writing an attribute and step on each other's
> data.
> When a WMI vendor driver declares a set of functions in a
> file_operations object the WMI bus driver will create a character
> device that maps to those file operations.
> The WMI vendor drivers will be responsible for managing access to
> this character device and proper locking on it.
> When a WMI vendor driver is unloaded the WMI bus driver will clean
> up the character device.

> @@ -44,12 +44,17 @@
> #include <linux/platform_device.h>
> #include <linux/wmi.h>
> #include <linux/uuid.h>
> +#include <linux/cdev.h>
> +#include <linux/idr.h>

Keep alphabetical ordering.

With Best Regards,
Andy Shevchenko