1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Scheduler code and data structures related to cpufreq.
 4 *
 5 * Copyright (C) 2016, Intel Corporation
 6 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 7 */
 8#include "sched.h"
 9
10DEFINE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data);
11
12/**
13 * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
14 * @cpu: The CPU to set the pointer for.
15 * @data: New pointer value.
16 * @func: Callback function to set for the CPU.
17 *
18 * Set and publish the update_util_data pointer for the given CPU.
19 *
20 * The update_util_data pointer of @cpu is set to @data and the callback
21 * function pointer in the target struct update_util_data is set to @func.
22 * That function will be called by cpufreq_update_util() from RCU-sched
23 * read-side critical sections, so it must not sleep.  @data will always be
24 * passed to it as the first argument which allows the function to get to the
25 * target update_util_data structure and its container.
26 *
27 * The update_util_data pointer of @cpu must be NULL when this function is
28 * called or it will WARN() and return with no effect.
29 */
30void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
31			void (*func)(struct update_util_data *data, u64 time,
32				     unsigned int flags))
33{
34	if (WARN_ON(!data || !func))
35		return;
36
37	if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
38		return;
39
40	data->func = func;
41	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
42}
43EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
44
45/**
46 * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
47 * @cpu: The CPU to clear the pointer for.
48 *
49 * Clear the update_util_data pointer for the given CPU.
50 *
51 * Callers must use RCU callbacks to free any memory that might be
52 * accessed via the old update_util_data pointer or invoke synchronize_rcu()
53 * right after this function to avoid use-after-free.
54 */
55void cpufreq_remove_update_util_hook(int cpu)
56{
57	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
58}
59EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Scheduler code and data structures related to cpufreq.
 4 *
 5 * Copyright (C) 2016, Intel Corporation
 6 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 7 */
 
 8
 9DEFINE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data);
10
11/**
12 * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
13 * @cpu: The CPU to set the pointer for.
14 * @data: New pointer value.
15 * @func: Callback function to set for the CPU.
16 *
17 * Set and publish the update_util_data pointer for the given CPU.
18 *
19 * The update_util_data pointer of @cpu is set to @data and the callback
20 * function pointer in the target struct update_util_data is set to @func.
21 * That function will be called by cpufreq_update_util() from RCU-sched
22 * read-side critical sections, so it must not sleep.  @data will always be
23 * passed to it as the first argument which allows the function to get to the
24 * target update_util_data structure and its container.
25 *
26 * The update_util_data pointer of @cpu must be NULL when this function is
27 * called or it will WARN() and return with no effect.
28 */
29void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
30			void (*func)(struct update_util_data *data, u64 time,
31				     unsigned int flags))
32{
33	if (WARN_ON(!data || !func))
34		return;
35
36	if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
37		return;
38
39	data->func = func;
40	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
41}
42EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
43
44/**
45 * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
46 * @cpu: The CPU to clear the pointer for.
47 *
48 * Clear the update_util_data pointer for the given CPU.
49 *
50 * Callers must use RCU callbacks to free any memory that might be
51 * accessed via the old update_util_data pointer or invoke synchronize_rcu()
52 * right after this function to avoid use-after-free.
53 */
54void cpufreq_remove_update_util_hook(int cpu)
55{
56	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
57}
58EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);
59
60/**
61 * cpufreq_this_cpu_can_update - Check if cpufreq policy can be updated.
62 * @policy: cpufreq policy to check.
63 *
64 * Return 'true' if:
65 * - the local and remote CPUs share @policy,
66 * - dvfs_possible_from_any_cpu is set in @policy and the local CPU is not going
67 *   offline (in which case it is not expected to run cpufreq updates any more).
68 */
69bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy)
70{
71	return cpumask_test_cpu(smp_processor_id(), policy->cpus) ||
72		(policy->dvfs_possible_from_any_cpu &&
73		 rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data)));
74}