From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751663AbdJBA53 (ORCPT ); Sun, 1 Oct 2017 20:57:29 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:41865 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750943AbdJBA51 (ORCPT ); Sun, 1 Oct 2017 20:57:27 -0400 Date: Sun, 1 Oct 2017 17:57:20 -0700 From: Darren Hart To: Greg Kroah-Hartman Cc: Mario Limonciello , Andy Shevchenko , LKML , platform-driver-x86@vger.kernel.org, Andy Lutomirski , quasisec@google.com, pali.rohar@gmail.com, Rafael Wysocki , Matthew Garrett , Christoph Hellwig Subject: Re: [PATCH v3 4/8] platform/x86: wmi: create character devices when requested by drivers Message-ID: <20171002005720.GA10424@fury> References: <17fcf9748e83ede2751a00d8248cb32cbdc610d6.1506571188.git.mario.limonciello@dell.com> <20170930015228.GC13307@fury> <20170930081205.GA22980@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170930081205.GA22980@kroah.com> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 30, 2017 at 10:12:05AM +0200, Greg Kroah-Hartman wrote: > On Fri, Sep 29, 2017 at 06:52:28PM -0700, Darren Hart wrote: > > > > On Wed, Sep 27, 2017 at 11:02:16PM -0500, Mario Limonciello 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. > > > > > > That character device will correspond to this path: > > > /dev/wmi/$driver > > > > > > This policy is selected as one driver may map and use multiple > > > GUIDs and it would be better to only expose a single character > > > device. > > > > > > 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. > > > > > > Signed-off-by: Mario Limonciello > > > --- > > > drivers/platform/x86/wmi.c | 98 +++++++++++++++++++++++++++++++++++++++++++--- > > > include/linux/wmi.h | 1 + > > > 2 files changed, 94 insertions(+), 5 deletions(-) > > > > +Greg, Rafael, Matthew, and Christoph > > > > You each provided feedback regarding the method of exposing WMI methods > > to userspace. This and subsequent patches from Mario lay some of the > > core groundwork. > > > > They implement an implicit whitelist as only drivers requesting the char > > dev will see it created. > > > > https://lkml.org/lkml/2017/9/28/8 > > If you want patchs reviewed, it's best to actually cc: us on the patch > itself :( > Of course. I didn't send the series, but thought you should see it. I could have asked Mario to resend, but I thought a pointer would have made it easy enough to find in your lkml folder, and it would avoid splitting the conversation which resending would inevitably lead to. I pruned this one because Christoph gets upset if I don't. We can wait for v4 I guess. And next time I want to get your take on something someone doesn't Cc you on, I'll just ask them to resend the whole series with you on Cc. -- Darren Hart VMware Open Source Technology Center