From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751946AbcBDFKD (ORCPT ); Thu, 4 Feb 2016 00:10:03 -0500 Received: from mail-pf0-f175.google.com ([209.85.192.175]:34430 "EHLO mail-pf0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751133AbcBDFJ7 (ORCPT ); Thu, 4 Feb 2016 00:09:59 -0500 Date: Thu, 4 Feb 2016 10:39:54 +0530 From: Viresh Kumar To: "Rafael J. Wysocki" Cc: Linux PM list , Linux Kernel Mailing List , Srinivas Pandruvada , Juri Lelli , Steve Muckle , Saravana Kannan Subject: Re: [PATCH 2/11] cpufreq: governor: Use common mutex for dbs_data protection Message-ID: <20160204050954.GU3469@vireshk> References: <3705929.bslqXH980s@vostro.rjw.lan> <1529283.0IedZktI9q@vostro.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1529283.0IedZktI9q@vostro.rjw.lan> 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 04-02-16, 00:16, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > Every governor relying on the common code in cpufreq_governor.c > has to provide its own mutex in struct common_dbs_data. However, > those mutexes are never used at the same time Why do you think so? I thought they can always be used in parallel. Consider 2 or more policies, one can have ondemand as the governor, whereas other one can have conservative. If CPUs go online/offline or if governors are switching in parallel, then cpufreq_governor_dbs() can very much run in parallel for ondemand and conservative. Or am I missing something here ? -- viresh