From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757455Ab3BRW02 (ORCPT ); Mon, 18 Feb 2013 17:26:28 -0500 Received: from mail-da0-f48.google.com ([209.85.210.48]:38160 "EHLO mail-da0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757272Ab3BRW0Y (ORCPT ); Mon, 18 Feb 2013 17:26:24 -0500 Date: Mon, 18 Feb 2013 14:26:18 -0800 From: Greg KH To: Borislav Petkov , Mauro Carvalho Chehab , 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: <20130218222618.GA21818@kroah.com> References: <20130218155215.GB2663@arwen.pp.htv.fi> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130218221306.GA21493@pd.tnic> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 18, 2013 at 11:13:06PM +0100, Borislav Petkov wrote: > On Mon, Feb 18, 2013 at 01:54:34PM -0800, Greg KH wrote: > > Because sysfs is "one value per file" the lack of a file showing up > > shouldn't cause any userspace tools any problems, that is why we did > > things this way. > > > > But, of course, userspace programmers do know how to mess things up... > > How about what I proposed earlier to Felipe: > > -- > diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c > index 0ca1ca71157f..d2eef76d1d46 100644 > --- a/drivers/edac/edac_mc_sysfs.c > +++ b/drivers/edac/edac_mc_sysfs.c > @@ -704,7 +704,7 @@ static ssize_t mci_sdram_scrub_rate_show(struct device *dev, > int bandwidth = 0; > > if (!mci->get_sdram_scrub_rate) > - return -ENODEV; > + return sprintf(data, "N/A"); > > bandwidth = mci->get_sdram_scrub_rate(mci); > if (bandwidth < 0) { > > -- > > Would that hurt the sysfs policy? In this case we *can* read the file > and it correctly tells us that scrub rate reading is not supported > instead of having a number there. > > Hmm. 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? thanks, greg k-h