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108c35a9 | 1 | // SPDX-License-Identifier: GPL-2.0 |
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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> | |
adaf9fcd | 7 | */ |
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8 | #include <linux/cpufreq.h> |
9 | ||
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10 | #include "sched.h" |
11 | ||
b10abd0a | 12 | DEFINE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data); |
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13 | |
14 | /** | |
0bed612b | 15 | * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer. |
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16 | * @cpu: The CPU to set the pointer for. |
17 | * @data: New pointer value. | |
0bed612b | 18 | * @func: Callback function to set for the CPU. |
adaf9fcd | 19 | * |
0bed612b | 20 | * Set and publish the update_util_data pointer for the given CPU. |
adaf9fcd | 21 | * |
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22 | * The update_util_data pointer of @cpu is set to @data and the callback |
23 | * function pointer in the target struct update_util_data is set to @func. | |
24 | * That function will be called by cpufreq_update_util() from RCU-sched | |
25 | * read-side critical sections, so it must not sleep. @data will always be | |
26 | * passed to it as the first argument which allows the function to get to the | |
27 | * target update_util_data structure and its container. | |
28 | * | |
29 | * The update_util_data pointer of @cpu must be NULL when this function is | |
30 | * called or it will WARN() and return with no effect. | |
adaf9fcd | 31 | */ |
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32 | void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data, |
33 | void (*func)(struct update_util_data *data, u64 time, | |
58919e83 | 34 | unsigned int flags)) |
adaf9fcd | 35 | { |
0bed612b | 36 | if (WARN_ON(!data || !func)) |
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37 | return; |
38 | ||
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39 | if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu))) |
40 | return; | |
41 | ||
42 | data->func = func; | |
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43 | rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data); |
44 | } | |
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45 | EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook); |
46 | ||
47 | /** | |
48 | * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer. | |
49 | * @cpu: The CPU to clear the pointer for. | |
50 | * | |
51 | * Clear the update_util_data pointer for the given CPU. | |
52 | * | |
b290ebcf PM |
53 | * Callers must use RCU callbacks to free any memory that might be |
54 | * accessed via the old update_util_data pointer or invoke synchronize_rcu() | |
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55 | * right after this function to avoid use-after-free. |
56 | */ | |
57 | void cpufreq_remove_update_util_hook(int cpu) | |
58 | { | |
59 | rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL); | |
60 | } | |
61 | EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook); | |
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62 | |
63 | /** | |
64 | * cpufreq_this_cpu_can_update - Check if cpufreq policy can be updated. | |
65 | * @policy: cpufreq policy to check. | |
66 | * | |
67 | * Return 'true' if: | |
68 | * - the local and remote CPUs share @policy, | |
69 | * - dvfs_possible_from_any_cpu is set in @policy and the local CPU is not going | |
70 | * offline (in which case it is not expected to run cpufreq updates any more). | |
71 | */ | |
72 | bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy) | |
73 | { | |
74 | return cpumask_test_cpu(smp_processor_id(), policy->cpus) || | |
75 | (policy->dvfs_possible_from_any_cpu && | |
76 | rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data))); | |
77 | } |