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Tue, 16 Jun 2020 02:54:40 -0700 (PDT) Date: Tue, 16 Jun 2020 15:24:38 +0530 From: Viresh Kumar To: Quentin Perret Cc: rjw@rjwysocki.net, rafael@kernel.org, arnd@arndb.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, kernel-team@android.com, tkjos@google.com, adharmap@codeaurora.org Subject: Re: [PATCH 2/2] cpufreq: Specify default governor on command line Message-ID: <20200616095438.v7wywhfq5ealvyih@vireshk-i7> References: <20200615165554.228063-1-qperret@google.com> <20200615165554.228063-3-qperret@google.com> <20200616043143.obk5k3rv737j5dnd@vireshk-i7> <20200616083107.GA122049@google.com> <20200616092759.rjnk3lef4tedfust@vireshk-i7> <20200616094802.GA139416@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200616094802.GA139416@google.com> User-Agent: NeoMutt/20180716-391-311a52 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16-06-20, 10:48, Quentin Perret wrote: > ---8<--- > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 0f05caedc320..a9219404e07f 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -2340,6 +2340,11 @@ int cpufreq_register_governor(struct cpufreq_governor *governor) > list_add(&governor->governor_list, &cpufreq_governor_list); > } > > + if (!strncasecmp(cpufreq_param_governor, governor->name, CPUFREQ_NAME_LEN)) > + default_governor = governor; > + else if (!default_governor && cpufreq_default_governor() == governor) > + default_governor = cpufreq_default_governor(); Instead of the else part here, maybe just do this from cpufreq_core_init() only once, and so we will always have default_governor set. > + > mutex_unlock(&cpufreq_governor_mutex); > return err; > } > @@ -2368,6 +2373,8 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor) > > mutex_lock(&cpufreq_governor_mutex); > list_del(&governor->governor_list); > + if (governor == default_governor) > + default_governor = cpufreq_default_governor(); > mutex_unlock(&cpufreq_governor_mutex); > } > EXPORT_SYMBOL_GPL(cpufreq_unregister_governor); > --->8--- > > should do the trick. That removes the unnecessary reference count, and > feels like a good place to hook things -- that is how cpuidle does it > too IIRC. > > I'll double check the locking/synchronization, but that shouldn't be too > bad (famous last words). > > Cheers, > Quentin -- viresh