From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [RFC][PATCH] cpufreq: Do not hold driver module references for additional policy CPUs Date: Thu, 01 Aug 2013 21:21:35 +0200 Message-ID: <7752148.JjTSgAt1Xy@vostro.rjw.lan> References: <2362640.pUofnXyzOi@vostro.rjw.lan> <1656801.jLHjvytfNU@vostro.rjw.lan> <51FAB083.5050900@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <51FAB083.5050900@linux.vnet.ibm.com> Sender: linux-pm-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: "Srivatsa S. Bhat" Cc: Viresh Kumar , Linux PM list , LKML , cpufreq@vger.kernel.org, Lists linaro-kernel On Friday, August 02, 2013 12:31:23 AM Srivatsa S. Bhat wrote: > On 08/02/2013 12:31 AM, Rafael J. Wysocki wrote: > > On Thursday, August 01, 2013 11:36:49 PM Srivatsa S. Bhat wrote: > >> Its the cpufreq_cpu_get() hidden away in cpufreq_add_dev_symlink(). With > >> that taken care of, everything should be OK. Then we can change the > >> synchronization part to avoid using refcounts. > > > > So I actually don't see why cpufreq_add_dev_symlink() needs to call > > cpufreq_cpu_get() at all, since the policy refcount is already 1 at the > > point it is called and the bumping up of the driver module refcount is > > pointless. > > > > Hmm, yes, it seems so. > > > However, if I change that I also need to change the piece of code that > > calls the complementary cpufreq_cpu_put() and I kind of cannot find it. > > > > ... I guess that's because you are looking at the code with your patch > applied (and your patch removed that _put()) ;-) No, it's not that one. That one was complementary to the cpufreq_cpu_get() done by cpufreq_add_policy_cpu() before my patch. Since my patch changes cpufreq_add_policy_cpu() to call cpufreq_cpu_put() before returning and bump up the policy refcount with kobject_get(), the one in __cpufreq_remove_dev() is changed into kobject_put() (correctly, IMO). What gives? Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.