From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751566AbdJCJXe (ORCPT ); Tue, 3 Oct 2017 05:23:34 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:33153 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751190AbdJCJXc (ORCPT ); Tue, 3 Oct 2017 05:23:32 -0400 X-ME-Sender: X-Sasl-enc: XmaRf2dUGWh8BsE3XgB/6PwYchQtPpB2H0no4Dy+yLri 1507022612 Date: Tue, 3 Oct 2017 11:23:42 +0200 From: Greg KH To: Mario Limonciello Cc: dvhart@infradead.org, Andy Shevchenko , LKML , platform-driver-x86@vger.kernel.org, Andy Lutomirski , quasisec@google.com, pali.rohar@gmail.com Subject: Re: [PATCH v3 4/8] platform/x86: wmi: create character devices when requested by drivers Message-ID: <20171003092342.GB13295@kroah.com> References: <17fcf9748e83ede2751a00d8248cb32cbdc610d6.1506571188.git.mario.limonciello@dell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <17fcf9748e83ede2751a00d8248cb32cbdc610d6.1506571188.git.mario.limonciello@dell.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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(-) > > diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c > index 4d73a87c2ddf..17399df87948 100644 > --- a/drivers/platform/x86/wmi.c > +++ b/drivers/platform/x86/wmi.c > @@ -34,7 +34,9 @@ > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > #include > +#include > #include > +#include > #include > #include > #include > @@ -50,6 +52,9 @@ MODULE_AUTHOR("Carlos Corbacho"); > MODULE_DESCRIPTION("ACPI-WMI Mapping Driver"); > MODULE_LICENSE("GPL"); > > +#define WMI_MAX_DEVS MINORMASK > +static DEFINE_IDR(wmi_idr); You never free the idr's memory when you unload the module :(