From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932949Ab3BSOQE (ORCPT ); Tue, 19 Feb 2013 09:16:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56895 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758334Ab3BSOQB (ORCPT ); Tue, 19 Feb 2013 09:16:01 -0500 Date: Tue, 19 Feb 2013 11:14:40 -0300 From: Mauro Carvalho Chehab To: Hannes Reinecke Cc: Borislav Petkov , Felipe Balbi , Greg KH , 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: <20130219111440.2b4b2e95@redhat.com> In-Reply-To: <512384EF.9020602@suse.de> References: <20130219101121.GJ23197@arwen.pp.htv.fi> <20130219081149.46972f56@redhat.com> <20130219114345.GA26623@pd.tnic> <20130219091610.2b746a30@redhat.com> <20130219123502.GD26623@pd.tnic> <20130219094640.2abf1a66@redhat.com> <20130219130626.GE26623@pd.tnic> <20130219131500.GW23197@arwen.pp.htv.fi> <20130219132853.GG26623@pd.tnic> <20130219133809.GA4390@arwen.pp.htv.fi> <20130219135056.GH26623@pd.tnic> <512384EF.9020602@suse.de> 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 Tue, 19 Feb 2013 14:58:07 +0100 Hannes Reinecke escreveu: > On 02/19/2013 02:50 PM, Borislav Petkov wrote: > > On Tue, Feb 19, 2013 at 03:38:09PM +0200, Felipe Balbi wrote: > >> because changing the permission will cause the same issue: > > > > Actually, I take that back. Mauro's patch will already create the file > > anyway: > > > > if (mci->set_sdram_scrub_rate || mci->get_sdram_scrub_rate) > > > > Adjusting the permissions is simply the last missing piece to this patch > > to make the interface to userspace 100% coherent. > > > > -- > > From: Mauro Carvalho Chehab > > Date: Tue, 19 Feb 2013 09:16:10 -0300 > > Subject: [PATCH] EDAC: only create sdram_scrub_rate where supported > > > > Currently, sdram_scrub_rate sysfs node is created even if the device > > doesn't support get/set the scub rate. Change the logic to only > > create this device node when the operation is supported. > > > > If only read or only write is supported, it will keep returning -ENODEV > > just like before. > > > > Reported-by: Felipe Balbi > > Signed-off-by: Mauro Carvalho Chehab > > --- > > drivers/edac/edac_mc_sysfs.c | 21 +++++++++++++++++++-- > > 1 file changed, 19 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c > > index 0ca1ca71157f..5a788e60ff67 100644 > > --- a/drivers/edac/edac_mc_sysfs.c > > +++ b/drivers/edac/edac_mc_sysfs.c > > @@ -7,7 +7,7 @@ > > * > > * Written Doug Thompson www.softwarebitmaker.com > > * > > - * (c) 2012 - Mauro Carvalho Chehab > > + * (c) 2012-2013 - Mauro Carvalho Chehab > > * The entire API were re-written, and ported to use struct device > > * > > */ > > @@ -878,7 +878,6 @@ static struct attribute *mci_attrs[] = { > > &dev_attr_ce_noinfo_count.attr, > > &dev_attr_ue_count.attr, > > &dev_attr_ce_count.attr, > > - &dev_attr_sdram_scrub_rate.attr, > > &dev_attr_max_location.attr, > > NULL > > }; > > @@ -1012,6 +1011,23 @@ int edac_create_sysfs_mci_device(struct mem_ctl_info *mci) > > return err; > > } > > > > + if (mci->set_sdram_scrub_rate || mci->get_sdram_scrub_rate) { > > + umode_t mode = 0; > > + > > + if (mci->get_sdram_scrub_rate) > > + mode = S_IRUGO; > > + > > + if (mci->set_sdram_scrub_rate) > > + mode |= S_IWUSR; > > + > > + dev_attr_sdram_scrub_rate.attr.mode = mode; > > + > > + err = device_create_file(&mci->dev, &dev_attr_sdram_scrub_rate); > > + if (err) { > > + edac_dbg(1, "failure: create sdram_scrub_rate\n"); > > + goto fail2; > > + } > > + } > > /* > > * Create the dimm/rank devices > > */ > > @@ -1056,6 +1072,7 @@ fail: > > continue; > > device_unregister(&dimm->dev); > > } > > +fail2: > > device_unregister(&mci->dev); > > bus_unregister(&mci->bus); > > kfree(mci->bus.name); > > > And of course you all know that creating sysfs attributes via > 'device_create_file' opens all sort of funny race conditions, > especially when checking these attributes from udev ... Yes, we know that, but this subsystem has already lots of other attributes created via device_create_file(). It used to be a lot worse than that, as, on a very recent past (before Kernel 3.5), those attributes were created via sysfs_create_file(). There's not much that can be done to avoid it on this subsystem. > > Please consider adding a default attribute which return '-EINVAL' or > somesuch when the function pointers are not set. > But _not_ adding it via device_create_file(). That's evil. This thread started with Felipe's complain about it returning -ENOSYS ;) when this feature is not supported. Regards, Mauro