From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757270AbaIOVzf (ORCPT ); Mon, 15 Sep 2014 17:55:35 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:32993 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755726AbaIOVzc (ORCPT ); Mon, 15 Sep 2014 17:55:32 -0400 Date: Mon, 15 Sep 2014 23:55:28 +0200 From: Frans Klaver To: Greg Kroah-Hartman Cc: Darren Hart , Corentin Chary , Rafael Wysocki , acpi4asus-user@lists.sourceforge.net, platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, "H. Peter Anvin" Subject: Re: [PATCH 10/13] eeepc-laptop: compare proper return values in get_cpufv Message-ID: <20140915215527.GC7867@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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20140915215125.GA21435@kroah.com> 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 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: > > On Sat, Sep 13, 2014 at 01:06:49AM +0200, Frans Klaver wrote: > > > In get_cpufv the return value of get_acpi is stored in the cpufv struct. > > > Right before this value is checked for errors, it is and'ed with 0xff. > > > This means c->cur can never be less than zero. Besides that, the actual > > > error value is ignored. > > > > > > c->num is also and'ed with 0xff, which means we can ignore values below > > > zero. > > > > > > Check the result of get_acpi() right away. While at it, propagate the > > > error if we got one. > > > > > > Signed-off-by: Frans Klaver > > > --- > > > drivers/platform/x86/eeepc-laptop.c | 5 ++++- > > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c > > > index 47488d3..828db56 100644 > > > --- a/drivers/platform/x86/eeepc-laptop.c > > > +++ b/drivers/platform/x86/eeepc-laptop.c > > > @@ -332,9 +332,12 @@ struct eeepc_cpufv { > > > static int get_cpufv(struct eeepc_laptop *eeepc, struct eeepc_cpufv *c) > > > { > > > c->cur = get_acpi(eeepc, CM_ASL_CPUFV); > > > + if (c->cur < 0) > > > + return c->cur; > > > + > > > c->num = (c->cur >> 8) & 0xff; > > > c->cur &= 0xff; > > > - if (c->cur < 0 || c->num <= 0 || c->num > 12) > > > + if (c->num == 0 || c->num > 12) > > > return -ENODEV; > > > return 0; > > > > 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. Thanks, Frans