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/*
* Scheduler code and data structures related to cpufreq.
*
* Copyright (C) 2016, Intel Corporation
* Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/cpufreq.h>
#include "sched.h"
DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
/**
* cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
* @cpu: The CPU to set the pointer for.
* @data: New pointer value.
* @func: Callback function to set for the CPU.
*
* Set and publish the update_util_data pointer for the given CPU.
*
* The update_util_data pointer of @cpu is set to @data and the callback
* function pointer in the target struct update_util_data is set to @func.
* That function will be called by cpufreq_update_util() from RCU-sched
* read-side critical sections, so it must not sleep. @data will always be
* passed to it as the first argument which allows the function to get to the
* target update_util_data structure and its container.
*
* The update_util_data pointer of @cpu must be NULL when this function is
* called or it will WARN() and return with no effect.
*/
void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
void (*func)(struct update_util_data *data, u64 time,
unsigned int flags))
{
if (WARN_ON(!data || !func))
return;
if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
return;
data->func = func;
rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
}
EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
/**
* cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
* @cpu: The CPU to clear the pointer for.
*
* Clear the update_util_data pointer for the given CPU.
*
* Callers must use RCU-sched callbacks to free any memory that might be
* accessed via the old update_util_data pointer or invoke synchronize_sched()
* right after this function to avoid use-after-free.
*/
void cpufreq_remove_update_util_hook(int cpu)
{
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 case 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)));
}
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