From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758587Ab3BSKDr (ORCPT ); Tue, 19 Feb 2013 05:03:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:11786 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757478Ab3BSKDn (ORCPT ); Tue, 19 Feb 2013 05:03:43 -0500 Date: Tue, 19 Feb 2013 07:03:10 -0300 From: Mauro Carvalho Chehab To: Borislav Petkov Cc: Greg KH , balbi@ti.com, Linux Kernel Mailing List , Steven Rostedt , Frederic Weisbecker , Ingo Molnar , JBottomley@parallels.com, linux-scsi@vger.kernel.org, davem@davemloft.net, netdev@vger.kernel.org, Doug Thompson , linux-edac@vger.kernel.org, rjw@sisk.pl, linux-pm@vger.kernel.org Subject: Re: SYSFS "errors" Message-ID: <20130219070310.2cadad7a@redhat.com> In-Reply-To: <20130218224405.GB21493@pd.tnic> References: <20130218171334.GA31329@kroah.com> <20130218172700.GH2663@arwen.pp.htv.fi> <20130218174916.GA2070@kroah.com> <20130218184633.GC10755@arwen.pp.htv.fi> <20130218164638.7cb53baa@redhat.com> <20130218200542.GB20137@arwen.pp.htv.fi> <20130218184742.5a4c3c06@redhat.com> <20130218215434.GB16794@kroah.com> <20130218221306.GA21493@pd.tnic> <20130218222618.GA21818@kroah.com> <20130218224405.GB21493@pd.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Mon, 18 Feb 2013 23:44:05 +0100 Borislav Petkov escreveu: > On Mon, Feb 18, 2013 at 02:26:18PM -0800, Greg KH wrote: > > I don't know, it depends on if userspace can handle this properly or > > not. What tools rely on this sysfs file? WHat happens when they get a > > non-number in the file? The thing with "sdram_scrub_rate" is that this is not supported by any userspace application I know. I suspect that this is used by userspace scripts. So, we'll never know in advance what behavior those scripts would expect. > > I'm not aware of any, frankly speaking. > > If there are any, those tools should be able to handle the -ENODEV > they get. Now, if this gets changed this way, the read would succeed > but they'll have to parse the returned value and see that it is not an > integer. > > So I don't know either. > > But my gut feeling says to stay concervative and not touch this code - > we don't know what uses it and how much we would break by "fixing" it. > The current situation is not that big of a deal IMVHO and I'd be willing > to accept the small inconcistency versus possibly breaking userspace. I remember I saw some discussions about it in the past at bluesmoke ML, saying that -ENODEV is the expected behavior when this is not supported. Changing from -ENODEV to "N/A" will break anything that would be relying on the previous behavior. So, I think that such change will for sure break userspace. If we're willing to change it, not creating the "sdram_scrub_rate" sysfs node is less likely to affect userspace. Regards, Mauro