From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mauro Carvalho Chehab Subject: Re: SYSFS "errors" Date: Tue, 19 Feb 2013 09:16:10 -0300 Message-ID: <20130219091610.2b746a30@redhat.com> References: <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> <20130219070310.2cadad7a@redhat.com> <20130219101121.GJ23197@arwen.pp.htv.fi> <20130219081149.46972f56@redhat.com> <20130219114345.GA26623@pd.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: balbi@ti.com, 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 To: Borislav Petkov Return-path: In-Reply-To: <20130219114345.GA26623@pd.tnic> Sender: linux-pm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Em Tue, 19 Feb 2013 12:43:46 +0100 Borislav Petkov escreveu: > On Tue, Feb 19, 2013 at 08:11:49AM -0300, Mauro Carvalho Chehab wrote= : > > > > I remember I saw some discussions about it in the past at blues= moke ML, > > > > saying that -ENODEV is the expected behavior when this is not s= upported. > > > >=20 > > > > Changing from -ENODEV to "N/A" will break anything that would b= e relying > > > > on the previous behavior. So, I think that such change will for= sure break > > > > userspace. > > > >=20 > > > > If we're willing to change it, not creating the "sdram_scrub_ra= te" sysfs=20 > > > > node is less likely to affect userspace. >=20 > This will break scripts which assume this file's presence implicitly. If are there any script like that, then yes. > [ =E2=80=A6 ] >=20 > > @@ -1017,6 +1010,14 @@ int edac_create_sysfs_mci_device(struct mem_= ctl_info *mci) > > return err; > > } > > =20 > > + if (mci->set_sdram_scrub_rate && mci->get_sdram_scrub_rate) { >=20 > This will break cpc925_edac.c because it defines a > ->get_sdram_scrub_rate but not a ->set_sdram_scrub_rate. True. Patch below fixes it. > I think a maybe better fix would be to figure out the sysfs file > permissions based on the presence of the two functions and *then* add > the attribute. >=20 > This way, the only visible change to userspace is the corrected sysfs > file permissions. I'm not sure if is there a way to pass fs permissions to something simi= lar to device_create_file(). On both cases, an error will happen at open: - if file doesn't exist (this approach), it will return -ENOENT; - if file is opened with wrong permissions, open will return -EPERM. However, if the file is not created, readdir() won't show the file. So, if userspace first seeks for the sdram_scrub_rate, it won't fail. That makes the logic below a little safer, IMO. [PATCH EDAC] 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 diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.= c index 9c58da6..29b66a2 100644 --- a/drivers/edac/edac_mc_sysfs.c +++ b/drivers/edac/edac_mc_sysfs.c @@ -7,7 +7,7 @@ * * Written Doug Thompson www.softwarebitmaker.co= m * - * (c) 2012 - Mauro Carvalho Chehab + * (c) 2012-2013 - Mauro Carvalho Chehab * The entire API were re-written, and ported to use struct device * */ @@ -882,7 +882,6 @@ static struct attribute *mci_attrs[] =3D { &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 }; @@ -1017,6 +1016,14 @@ int edac_create_sysfs_mci_device(struct mem_ctl_= info *mci) return err; } =20 + if (mci->set_sdram_scrub_rate || mci->get_sdram_scrub_rate) { + err =3D 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 */ @@ -1061,6 +1068,7 @@ fail: continue; device_unregister(&dimm->dev); } +fail2: device_unregister(&mci->dev); bus_unregister(&mci->bus); kfree(mci->bus.name);