Re: [PATCH 2/2] cpufreq: Specify default governor on command line

From: Viresh Kumar
Date: Tue Jun 16 2020 - 00:31:50 EST


On 15-06-20, 17:55, Quentin Perret wrote:
> +static void cpufreq_get_default_governor(void)
> +{
> + default_governor = cpufreq_parse_governor(cpufreq_param_governor);
> + if (!default_governor) {
> + if (*cpufreq_param_governor)
> + pr_warn("Failed to find %s\n", cpufreq_param_governor);
> + default_governor = cpufreq_default_governor();

A module_get() never happened for this case and so maybe a
module_put() should never get called.

> + }
> +}
> +
> +static void cpufreq_put_default_governor(void)
> +{
> + if (!default_governor)
> + return;
> + module_put(default_governor->owner);
> + default_governor = NULL;
> +}
> +
> static int cpufreq_init_governor(struct cpufreq_policy *policy)
> {
> int ret;
> @@ -2701,6 +2721,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
>
> if (driver_data->setpolicy)
> driver_data->flags |= CPUFREQ_CONST_LOOPS;
> + else
> + cpufreq_get_default_governor();
>
> if (cpufreq_boost_supported()) {
> ret = create_boost_sysfs_file();
> @@ -2769,6 +2791,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
> subsys_interface_unregister(&cpufreq_interface);
> remove_boost_sysfs_file();
> cpuhp_remove_state_nocalls_cpuslocked(hp_online);
> + cpufreq_put_default_governor();
>
> write_lock_irqsave(&cpufreq_driver_lock, flags);
>
> @@ -2792,4 +2815,5 @@ static int __init cpufreq_core_init(void)
> return 0;
> }

And since this is a per boot thing, there is perhaps no need of doing
these at driver register/unregister, I would rather do it at:
cpufreq_core_init() time itself and so we will never need to run
cpufreq_put_default_governor() and so can be removed.

And another thing I am not able to understand (despite you commenting
about that in the commit log) is what happens if the default governor
chosen is built as a module ?

--
viresh