From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751621AbcBEIeW (ORCPT ); Fri, 5 Feb 2016 03:34:22 -0500 Received: from mx2.suse.de ([195.135.220.15]:51258 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750789AbcBEIeQ (ORCPT ); Fri, 5 Feb 2016 03:34:16 -0500 Date: Fri, 5 Feb 2016 09:34:13 +0100 From: Johannes Thumshirn To: Tyrel Datwyler Cc: Tyrel Datwyler , martin.petersen@oracle.com, linux-scsi@vger.kernel.org, JBottomley@odin.com, linux-kernel@vger.kernel.org, hare@suse.de, brking@linux.vnet.ibm.com, nfont@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 5/6] ibmvscsi: Remove unsupported host config MAD and sysfs interface Message-ID: <20160205083413.GF27969@c203.arch.suse.de> References: <1454542114-1797-1-git-send-email-tyreld@linux.vnet.ibm.com> <1454542114-1797-6-git-send-email-tyreld@linux.vnet.ibm.com> <20160204080317.GT27969@c203.arch.suse.de> <56B38EE7.6060102@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <56B38EE7.6060102@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 04, 2016 at 09:48:23AM -0800, Tyrel Datwyler wrote: > On 02/04/2016 12:03 AM, Johannes Thumshirn wrote: > > On Wed, Feb 03, 2016 at 05:28:33PM -0600, Tyrel Datwyler wrote: > >> A VIOSRP_HOST_CONFIG_TYPE management datagram (MAD) has existed in > >> the code for some time. From what information I've gathered from > >> Brian King this was likely implemented on the host side in a SLES 9 > >> based VIOS, which is no longer supported anywhere. Further, it is > >> not defined in PAPR or supported by any AIX based VIOS. > >> > >> Treating as bit rot and removing the sysfs interface and associated > >> host config code accordingly. > > > > Doesn't removing a sysfs interface potentially break userspace code? > > > > In the general case yes, but I feel in this case no. First, Reading from > this config attribute of a vscsi host adapter always returns nothing. > Second, any userspace code using this attribute better be checking for > the existence of config. Just a quick look for > /sys/class/scsi_host/host*/config under other host adapters on my system > I find that attribute doesn't exist for any of them. > > If there is truly enough concern that somebody may actually be accessing > this useless attribute from userspace then we can still strip out the > unsupported code, but leave the attribute and return nothing directly > from the show function. Which is what I kinda prefer. Slowly deprecate and phase out, but don't break userspace. You never know who is writing some obscure piece of code relaying on some sysfs attribute. Thanks, Johannes -- Johannes Thumshirn Storage jthumshirn@suse.de +49 911 74053 689 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg) Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850