From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH v2 12/12] cpufreq: governor: Narrow down the dbs_data_mutex coverage Date: Fri, 19 Feb 2016 08:08:14 +0530 Message-ID: <20160219023814.GD16983@vireshk-i7> References: <2938006.67J0esUvOA@vostro.rjw.lan> <8616971.q0P8tF6lFz@vostro.rjw.lan> <20160218062040.GR2610@vireshk-i7> <2559441.qfMQ0Nj7fb@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pa0-f49.google.com ([209.85.220.49]:34007 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1947901AbcBSCi2 (ORCPT ); Thu, 18 Feb 2016 21:38:28 -0500 Received: by mail-pa0-f49.google.com with SMTP id fy10so41683854pac.1 for ; Thu, 18 Feb 2016 18:38:28 -0800 (PST) Content-Disposition: inline In-Reply-To: <2559441.qfMQ0Nj7fb@vostro.rjw.lan> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Rafael J. Wysocki" Cc: Linux PM list , Linux Kernel Mailing List On 18-02-16, 18:58, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > Subject: [PATCH] cpufreq: governor: Narrow down the dbs_data_mutex coverage > > Since cpufreq_governor_dbs() is now always called with policy->rwsem > held, it cannot be executed twice in parallel for the same policy. > Thus it is not necessary to hold dbs_data_mutex around the invocations > of cpufreq_governor_start/stop/limits() from it as those functions > never modify any data that can be shared between different policies. > > However, cpufreq_governor_dbs() may be executed twice in parallal > for different policies using the same gov->gdbs_data object and > dbs_data_mutex is still necessary to protect that object against > concurrent updates. > > For this reason, narrow down the dbs_data_mutex locking to > cpufreq_governor_init/exit() where it is needed and rename the > mutex to gov_dbs_data_mutex to reflect its purpose. > > Signed-off-by: Rafael J. Wysocki > --- > drivers/cpufreq/cpufreq_governor.c | 46 ++++++++++++++++++------------------- > 1 file changed, 23 insertions(+), 23 deletions(-) Acked-by: Viresh Kumar -- viresh