> -----Original Message----- > From: Andy Shevchenko [mailto:andy.shevchenko@xxxxxxxxx] > Sent: Thursday, September 21, 2017 11:47 AM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Cc: dvhart@xxxxxxxxxxxxx; LKML <linux-kernel@xxxxxxxxxxxxxxx>; Platform Driver > <platform-driver-x86@xxxxxxxxxxxxxxx>; quasisec@xxxxxxxxxx; Pali Rohár > <pali.rohar@xxxxxxxxx> > Subject: Re: [PATCH 09/12] platform/x86: wmi: create character devices when > requested by drivers > > 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. > The existing list wasn't in alphabetical order. I'll submit a patch in v2 earlier in the series to sort and then put them in the right place for my patch.
