From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754735AbbGYNAM (ORCPT ); Sat, 25 Jul 2015 09:00:12 -0400 Received: from mail-pa0-f44.google.com ([209.85.220.44]:34092 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753297AbbGYNAJ (ORCPT ); Sat, 25 Jul 2015 09:00:09 -0400 Date: Sat, 25 Jul 2015 18:30:02 +0530 From: Viresh Kumar To: "Rafael J. Wysocki" Cc: Linux PM list , Linux Kernel Mailing List , Russell King Subject: Re: [PATCH v2] cpufreq: Avoid attempts to create duplicate symbolic links Message-ID: <20150725130002.GC1691@linux> References: <1660815.CyKx9SEI9c@vostro.rjw.lan> <20150724140943.GC16336@linux> <1509688.KKhdi8M36y@vostro.rjw.lan> <11080992.c5Q5Du7n5n@vostro.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <11080992.c5Q5Du7n5n@vostro.rjw.lan> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25-07-15, 00:17, Rafael J. Wysocki wrote: > To avoid that warning, use the observation that cpufreq doesn't > need to care about CPUs that have never been online. I have concerns over the very philosophy behind the patch and so wanted to discuss more on that. It will be really confusing to have a scenario where: - we have a four related CPUs: 0-3. - 0-1 are online and have /sys/devices/system/cpu/cpuX/cpufreq directory - 2 is offline but was once online and so still has a directory - 3 never came online after the cpufreq driver is registered (we need to think about cpufreq driver being a module here, its possible CPU was online earlier) and so it doesn't have a directory. How will the user distinguish between cpu 3 and 4, both being offline and user may not know one of them was never online. And the related CPUs of 0-2 will include CPU 3 as well.. I think, we just moved into the wrong direction. We have a valid policy for CPU4, with all valid data. Why not show it up in sysfs? So, what we discussed over IRC earlier was, cpufreq shouldn't care about CPUs, which are offline and that don't have a policy allocated for them. So if all the CPUs of a policy never came online after the driver is registered, we shouldn't care about them. I think, for know your earlier version of the patch was just fine, with the improvements I suggested. And we should go ahead with solution like what I gave, the diff of that was quite big for an rc fix and so I said your patch looks better. -- viresh