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adaf9fcd RW |
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 | */ | |
adaf9fcd RW |
11 | #include "sched.h" |
12 | ||
13 | DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data); | |
14 | ||
15 | /** | |
0bed612b | 16 | * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer. |
adaf9fcd RW |
17 | * @cpu: The CPU to set the pointer for. |
18 | * @data: New pointer value. | |
0bed612b | 19 | * @func: Callback function to set for the CPU. |
adaf9fcd | 20 | * |
0bed612b | 21 | * Set and publish the update_util_data pointer for the given CPU. |
adaf9fcd | 22 | * |
0bed612b RW |
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. | |
adaf9fcd | 32 | */ |
0bed612b RW |
33 | void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data, |
34 | void (*func)(struct update_util_data *data, u64 time, | |
58919e83 | 35 | unsigned int flags)) |
adaf9fcd | 36 | { |
0bed612b | 37 | if (WARN_ON(!data || !func)) |
adaf9fcd RW |
38 | return; |
39 | ||
0bed612b RW |
40 | if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu))) |
41 | return; | |
42 | ||
43 | data->func = func; | |
adaf9fcd RW |
44 | rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data); |
45 | } | |
0bed612b RW |
46 | EXPORT_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 | */ | |
58 | void cpufreq_remove_update_util_hook(int cpu) | |
59 | { | |
60 | rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL); | |
61 | } | |
62 | EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook); |