From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754134AbaIPVKI (ORCPT ); Tue, 16 Sep 2014 17:10:08 -0400 Received: from mail-wg0-f41.google.com ([74.125.82.41]:58191 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753429AbaIPVKF (ORCPT ); Tue, 16 Sep 2014 17:10:05 -0400 Date: Tue, 16 Sep 2014 23:10:01 +0200 From: Frans Klaver To: Darren Hart Cc: Greg Kroah-Hartman , Corentin Chary , Rafael Wysocki , acpi4asus-user , platform-driver-x86 , linux-kernel@vger.kernel.org, linux-acpi , "H. Peter Anvin" Subject: Re: [PATCH 10/13] eeepc-laptop: compare proper return values in get_cpufv Message-ID: <20140916211001.GA23674@gmail.com> References: <1410563212-31565-1-git-send-email-fransklaver@gmail.com> <1410563212-31565-11-git-send-email-fransklaver@gmail.com> <20140915214902.GB64909@vmdeb7> <20140915215125.GA21435@kroah.com> <20140915215527.GC7867@gmail.com> <20140916205247.GA6856@vmdeb7> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20140916205247.GA6856@vmdeb7> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 16, 2014 at 01:52:47PM -0700, Darren Hart wrote: > On Tue, Sep 16, 2014 at 01:54:25PM +0200, Frans Klaver wrote: > > On Mon, Sep 15, 2014 at 11:55 PM, Frans Klaver wrote: > > > On Mon, Sep 15, 2014 at 02:51:25PM -0700, Greg Kroah-Hartman wrote: > > >> On Mon, Sep 15, 2014 at 02:49:02PM -0700, Darren Hart wrote: > > >> > > > >> > This patch is fine as is. However, Greg has supported propogating the error code > > >> > through to the sysfs interface (if I understand him correctly on an earlier post > > >> > to this list). This would require an addition change to this patch would > > >> > propogated the get_cpufv error code in show_available_cpuv(), show_cpuv(), and > > >> > store_cpuv(). As it is, we return -ENODEV on any failure, where an ACPI call > > >> > error should probably return -ENXIO as I understand it. > > >> > > >> I really have no idea at this point in time what to recommend. How > > >> about just stick with what is happening today so that: > > >> > > >> > However, there was a rather famous change in error code handling in which pulse > > >> > audio broke and Linus was very upset with one of his maintainers. > > >> > > >> That doesn't happen :) > > > > > > So if I interpret that correctly, we're dropping the last patch > > > (ENODEV -> ENXIO) from the series? That's fine by me. As mentioned > > > earlier, I already saw something else break because I returned ENXIO > > > instead of ENODEV. > > > > > > Maybe it's a good idea to try and document the expected behavior > > > somewhere, if even Greg isn't sure what to do. > > > > For good measure: > > > > v2 will not change the return values at the sysfs interface, meaning > > we will always return -ENODEV on error. I am going to try to keep as > > much internal functions propagating errors as possible though, unless > > someone strongly disagrees. > > > > Thanks, > > Frans > > I cornered Linus today and asked about this specifically. The policy is this: > > Don't change the sysfs return codes without good reason. A good reason could be > a real bug or problem with the return codes. It could also be to consolidate > error handling which makes things more uniform, etc. > > If this results in broken userspace, the maintainer will revert the change. Alright, that is basically what I was expecting it to be. As it happens, this also means that we'll have to decide what to do about returning -EIO/-ENODEV/rv in show_sys_acpi and store_sys_acpi. The latter was changed by Paul Bolle's "eeepc-laptop: simplify parse_arg()". The return value of these functions is propagated to the sysfs interface. > This is probably a good thing to add to sysfs-rules.txt. I'll prepare a patch. Agreed. While I was removing the patches changing the sysfs error behavior, I also noticed that eeepc-laptop.c doesn't really seem to handle errors uniformly. In some cases the callers of get_acpi and set_acpi don't even seem to consider that these functions may return an error code (e.g. eeepc_hotk_thaw()). I'd fix those in a new series though. Frans