From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762353AbcALLRh (ORCPT ); Tue, 12 Jan 2016 06:17:37 -0500 Received: from mail-pa0-f49.google.com ([209.85.220.49]:36123 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751943AbcALLRd (ORCPT ); Tue, 12 Jan 2016 06:17:33 -0500 Date: Tue, 12 Jan 2016 16:47:29 +0530 From: Viresh Kumar To: Juri Lelli Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, peterz@infradead.org, rjw@rjwysocki.net, mturquette@baylibre.com, steve.muckle@linaro.org, vincent.guittot@linaro.org, morten.rasmussen@arm.com, dietmar.eggemann@arm.com Subject: Re: [RFC PATCH 17/19] cpufreq: stop checking for cpufreq_driver being present in cpufreq_cpu_get Message-ID: <20160112111729.GI1084@ubuntu> References: <1452533760-13787-1-git-send-email-juri.lelli@arm.com> <1452533760-13787-18-git-send-email-juri.lelli@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1452533760-13787-18-git-send-email-juri.lelli@arm.com> 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 11-01-16, 17:35, Juri Lelli wrote: > After cpufreq_driver_lock() is acquired in cpufreq_cpu_get() we are sure > we can't race with cpufreq_policy_free() (which is in the path that ends > up removing cpufreq_driver). We can thus safely remove check for > cpufreq_driver being present (which is a leftover from commit > 6eed9404ab3c ("cpufreq: Use rwsem for protecting critical sections")). > > Cc: "Rafael J. Wysocki" > Cc: Viresh Kumar > Signed-off-by: Juri Lelli > --- > drivers/cpufreq/cpufreq.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 797bfae..6c9bef7 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -282,15 +282,15 @@ struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu) > if (WARN_ON(cpu >= nr_cpu_ids)) > return NULL; > > - /* get the cpufreq driver */ > read_lock_irqsave(&cpufreq_driver_lock, flags); > > - if (cpufreq_driver) { > - /* get the CPU */ > - policy = cpufreq_cpu_get_raw(cpu); > - if (policy) > - kobject_get(&policy->kobj); > - } > + /* > + * If we get a policy, cpufreq_policy_free() didn't > + * yet run. > + */ > + policy = cpufreq_cpu_get_raw(cpu); > + if (policy) > + kobject_get(&policy->kobj); > > read_unlock_irqrestore(&cpufreq_driver_lock, flags); Acked-by: Viresh Kumar -- viresh