Re: About CPU hot-plug stress test failed in cpufreq driver

[Viresh Kumar <viresh.kumar@linaro.org>]

On 10-12-19, 11:39, Rafael J. Wysocki wrote:
> Index: linux-pm/kernel/sched/cpufreq.c
> ===================================================================
> --- linux-pm.orig/kernel/sched/cpufreq.c
> +++ linux-pm/kernel/sched/cpufreq.c
> @@ -5,6 +5,8 @@
>   * Copyright (C) 2016, Intel Corporation
>   * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>   */
> +#include <linux/cpufreq.h>
> +
>  #include "sched.h"
>  
>  DEFINE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data);
> @@ -57,3 +59,19 @@ void cpufreq_remove_update_util_hook(int
>  	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
>  }
>  EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);
> +
> +/**
> + * cpufreq_this_cpu_can_update - Check if cpufreq policy can be updated.
> + * @policy: cpufreq policy to check.
> + *
> + * Return 'true' if:
> + * - the local and remote CPUs share @policy,
> + * - dvfs_possible_from_any_cpu is set in @policy and the local CPU is not going
> + *   offline (in which it is not expected to run cpufreq updates any more).
> + */
> +bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy)
> +{
> +	return cpumask_test_cpu(smp_processor_id(), policy->cpus) ||
> +		(policy->dvfs_possible_from_any_cpu &&

> +		 rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data)));

I somehow feel that doing this particular check in cpufreq_update_util() maybe
better. Or maybe we can call cpufreq_this_cpu_can_update() itself right from
cpufreq_update_util() instead and remove it from multiple places in the
governors.

-- 
viresh