From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751476AbdFZRGS (ORCPT ); Mon, 26 Jun 2017 13:06:18 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:38763 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751101AbdFZRGO (ORCPT ); Mon, 26 Jun 2017 13:06:14 -0400 Date: Mon, 26 Jun 2017 10:06:11 -0700 From: Guenter Roeck To: Sudip Mukherjee Cc: Jean Delvare , linux-kernel@vger.kernel.org, Fenghua Yu , linux-hwmon@vger.kernel.org Subject: Re: userspace regression with hwmon Message-ID: <20170626170611.GC20491@roeck-us.net> References: <20170626143320.GA1976@sudip-tp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170626143320.GA1976@sudip-tp> User-Agent: Mutt/1.5.24 (2015-08-30) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: guenter@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 26, 2017 at 03:33:20PM +0100, Sudip Mukherjee wrote: > Hi Guenter, Jean, > > The patch d72d19c26c41 ("hwmon: (coretemp) Convert to use > devm_hwmon_device_register_with_groups") has changed the location of the > sysfs nodes from /sys/devices/platform/coretemp.0/ to > /sys/devices/platform/coretemp.0/hwmon/hwmon0/ and that has broken > some of our usespace applications when we have updated the kernel from > v3.8 to v4.4. For now I am reverting that said patch in our production > kernel (based on v4.4) but that is not an elegant solution. > Do you have any other reports like this? I am sure changing the paths > upstream will now break some other userspace. So, what can be an elegant > solution to our problem? or do we always need to carry an out-of-tree > patch for our production kernel? > The problem only occurs if attributes are accessed using the raw path, and if user space does not take into account that attributes may reside in the hwmon directory (/sys/class/hwmon/hwmonX) _or_ in the device directory (/sys/class/hwmon/hwmonX/device). There is no guarantee that the raw path doesn't change from release to release; that is what the symlinks are for. Actually, I have seen the raw platform device path change over time, so I am surprised that this never affected you. You might consider using libsensors to access the attributes. Thanks, Guenter