From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751985AbdI0SzT (ORCPT ); Wed, 27 Sep 2017 14:55:19 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:45387 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751467AbdI0SzR (ORCPT ); Wed, 27 Sep 2017 14:55:17 -0400 Date: Wed, 27 Sep 2017 11:55:14 -0700 From: Darren Hart To: Andy Shevchenko , Andy Lutomirski Cc: Mario Limonciello , Pali =?iso-8859-1?Q?Roh=E1r?= , "linux-kernel@vger.kernel.org" , Platform Driver , quasisec@google.com Subject: Re: [PATCH 06/12] platform/x86: dell-wmi-smbios: Add a sysfs interface for SMBIOS tokens Message-ID: <20170927185514.GN23572@fury> References: <1342f21a4f2c9af86d3033a9af9d9a4d05d27106.1505999739.git.mario.limonciello@dell.com> <20170925162333.GL22190@pali> <20170927165051.GE23572@fury> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Wed, Sep 27, 2017 at 09:31:47PM +0300, Andy Shevchenko wrote: > On Wed, Sep 27, 2017 at 9:27 PM, wrote: > > >> > > > Darren, Andy, any comments? I'm not quite sure if such API is suitable > >> > > > for long term in kernel. > >> > > > >> > > I would try to avoid sysfs interfaces for some particular devices. > >> > > Besides we are creating a character device. Would it be suitable there? > >> > > >> > If the character device having 2 different ioctls for different needs is > >> > acceptable I'm happy to adjust the series to do this instead. > >> > >> One piece of feedback I had re the char device was to see if we could avoid the > >> need for the IOCTL altogether, I'd like to have that discussion before we add > >> another. > > > > My original design was sysfs files for everything but it was raised by several folks > > that you run into the potential of two userspace processes stomping on each > > other's data when they run the ACPI call. That's why I need to have a mutex to > > protect and make sure that userspace calls get the right results. > > > > >> > > > Basically tokens are list of tuples with > >> > > > possibility to active them, right? > >> > > > > >> > > >> > I didn't add a way to activate them through this, it was only for > >> > reading purpose. Activating them should be possible through the > >> > SMBIOS calling interface though. > >> > > >> > >> These are read-only as I understood it, and only with the right privileges. > >> Sysfs seemed appropriate for this to me. > > > > Andy S was against having this data as another sysfs file. From a userspace > > perspective I think it's simpler to just parse a sysfs file with read only static > > data as root. With the current ioctl based solution it requires userspace to run > > an ioctl to determine how many tokens exist, then allocate a chunk of memory > > big enough to hold all the token data and then run another ioctl to get all the tokens. > > > > Andy S, given this change between v1 and v2 what do you feel is better? > > I have no strong opinion on this. That's why I recommended to listen to Andy L. +Andy Lutomirski Andy L, any preference on your part regarding exporting these tokens via sysfs or through an additional IOCTL in the chardev? -- Darren Hart VMware Open Source Technology Center