1 // SPDX-License-Identifier: GPL-2.0 <<
2 /* 1 /*
3 * Scheduler code and data structures related 2 * Scheduler code and data structures related to cpufreq.
4 * 3 *
5 * Copyright (C) 2016, Intel Corporation 4 * Copyright (C) 2016, Intel Corporation
6 * Author: Rafael J. Wysocki <rafael.j.wysocki 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.
7 */ 10 */
>> 11 #include <linux/cpufreq.h>
>> 12
>> 13 #include "sched.h"
8 14
9 DEFINE_PER_CPU(struct update_util_data __rcu * !! 15 DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
10 16
11 /** 17 /**
12 * cpufreq_add_update_util_hook - Populate the 18 * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
13 * @cpu: The CPU to set the pointer for. 19 * @cpu: The CPU to set the pointer for.
14 * @data: New pointer value. 20 * @data: New pointer value.
15 * @func: Callback function to set for the CPU 21 * @func: Callback function to set for the CPU.
16 * 22 *
17 * Set and publish the update_util_data pointe 23 * Set and publish the update_util_data pointer for the given CPU.
18 * 24 *
19 * The update_util_data pointer of @cpu is set 25 * The update_util_data pointer of @cpu is set to @data and the callback
20 * function pointer in the target struct updat 26 * function pointer in the target struct update_util_data is set to @func.
21 * That function will be called by cpufreq_upd 27 * That function will be called by cpufreq_update_util() from RCU-sched
22 * read-side critical sections, so it must not 28 * read-side critical sections, so it must not sleep. @data will always be
23 * passed to it as the first argument which al 29 * passed to it as the first argument which allows the function to get to the
24 * target update_util_data structure and its c 30 * target update_util_data structure and its container.
25 * 31 *
26 * The update_util_data pointer of @cpu must b 32 * The update_util_data pointer of @cpu must be NULL when this function is
27 * called or it will WARN() and return with no 33 * called or it will WARN() and return with no effect.
28 */ 34 */
29 void cpufreq_add_update_util_hook(int cpu, str 35 void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
30 void (*func)(struct up 36 void (*func)(struct update_util_data *data, u64 time,
31 unsigned 37 unsigned int flags))
32 { 38 {
33 if (WARN_ON(!data || !func)) 39 if (WARN_ON(!data || !func))
34 return; 40 return;
35 41
36 if (WARN_ON(per_cpu(cpufreq_update_uti 42 if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
37 return; 43 return;
38 44
39 data->func = func; 45 data->func = func;
40 rcu_assign_pointer(per_cpu(cpufreq_upd 46 rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
41 } 47 }
42 EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook 48 EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
43 49
44 /** 50 /**
45 * cpufreq_remove_update_util_hook - Clear the 51 * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
46 * @cpu: The CPU to clear the pointer for. 52 * @cpu: The CPU to clear the pointer for.
47 * 53 *
48 * Clear the update_util_data pointer for the 54 * Clear the update_util_data pointer for the given CPU.
49 * 55 *
50 * Callers must use RCU callbacks to free any !! 56 * Callers must use RCU-sched callbacks to free any memory that might be
51 * accessed via the old update_util_data point !! 57 * accessed via the old update_util_data pointer or invoke synchronize_sched()
52 * right after this function to avoid use-afte 58 * right after this function to avoid use-after-free.
53 */ 59 */
54 void cpufreq_remove_update_util_hook(int cpu) 60 void cpufreq_remove_update_util_hook(int cpu)
55 { 61 {
56 rcu_assign_pointer(per_cpu(cpufreq_upd 62 rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
57 } 63 }
58 EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_h 64 EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);
59 65
60 /** 66 /**
61 * cpufreq_this_cpu_can_update - Check if cpuf 67 * cpufreq_this_cpu_can_update - Check if cpufreq policy can be updated.
62 * @policy: cpufreq policy to check. 68 * @policy: cpufreq policy to check.
63 * 69 *
64 * Return 'true' if: 70 * Return 'true' if:
65 * - the local and remote CPUs share @policy, 71 * - the local and remote CPUs share @policy,
66 * - dvfs_possible_from_any_cpu is set in @pol 72 * - 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 73 * offline (in which case it is not expected to run cpufreq updates any more).
68 */ 74 */
69 bool cpufreq_this_cpu_can_update(struct cpufre 75 bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy)
70 { 76 {
71 return cpumask_test_cpu(smp_processor_ 77 return cpumask_test_cpu(smp_processor_id(), policy->cpus) ||
72 (policy->dvfs_possible_from_an 78 (policy->dvfs_possible_from_any_cpu &&
73 rcu_dereference_sched(*this_c 79 rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data)));
74 } 80 }
75 81
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