1/*
 2 * Scheduler code and data structures related to cpufreq.
 3 *
 4 * Copyright (C) 2016, Intel Corporation
 5 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 6 *
 7 * This program is free software; you can redistribute it and/or modify
 8 * it under the terms of the GNU General Public License version 2 as
 9 * published by the Free Software Foundation.
10 */
11#include "sched.h"
12
13DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
14
15/**
16 * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
17 * @cpu: The CPU to set the pointer for.
18 * @data: New pointer value.
19 * @func: Callback function to set for the CPU.
20 *
21 * Set and publish the update_util_data pointer for the given CPU.
22 *
23 * The update_util_data pointer of @cpu is set to @data and the callback
24 * function pointer in the target struct update_util_data is set to @func.
25 * That function will be called by cpufreq_update_util() from RCU-sched
26 * read-side critical sections, so it must not sleep.  @data will always be
27 * passed to it as the first argument which allows the function to get to the
28 * target update_util_data structure and its container.
29 *
30 * The update_util_data pointer of @cpu must be NULL when this function is
31 * called or it will WARN() and return with no effect.
32 */
33void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
34			void (*func)(struct update_util_data *data, u64 time,
35				     unsigned int flags))
36{
37	if (WARN_ON(!data || !func))
38		return;
39
40	if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
41		return;
42
43	data->func = func;
44	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
45}
46EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
47
48/**
49 * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
50 * @cpu: The CPU to clear the pointer for.
51 *
52 * Clear the update_util_data pointer for the given CPU.
53 *
54 * Callers must use RCU-sched callbacks to free any memory that might be
55 * accessed via the old update_util_data pointer or invoke synchronize_sched()
56 * right after this function to avoid use-after-free.
57 */
58void cpufreq_remove_update_util_hook(int cpu)
59{
60	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
61}
62EXPORT_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#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);