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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 <linux/cpufreq.h> 9 : : 10 : : #include "sched.h" 11 : : 12 : : DEFINE_PER_CPU(struct update_util_data __rcu *, cpufreq_update_util_data); 13 : : 14 : : /** 15 : : * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer. 16 : : * @cpu: The CPU to set the pointer for. 17 : : * @data: New pointer value. 18 : : * @func: Callback function to set for the CPU. 19 : : * 20 : : * Set and publish the update_util_data pointer for the given CPU. 21 : : * 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. 31 : : */ 32 : 0 : void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data, 33 : : void (*func)(struct update_util_data *data, u64 time, 34 : : unsigned int flags)) 35 : : { 36 [ # # # # ]: 0 : if (WARN_ON(!data || !func)) 37 : : return; 38 : : 39 [ # # # # ]: 0 : if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu))) 40 : : return; 41 : : 42 : 0 : data->func = func; 43 : 0 : rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data); 44 : : } 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 : : * 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() 55 : : * right after this function to avoid use-after-free. 56 : : */ 57 : 0 : void cpufreq_remove_update_util_hook(int cpu) 58 : : { 59 : 0 : rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL); 60 : 0 : } 61 : : EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook); 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 : 0 : bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy) 73 : : { 74 [ # # ]: 0 : return cpumask_test_cpu(smp_processor_id(), policy->cpus) || 75 [ # # # # ]: 0 : (policy->dvfs_possible_from_any_cpu && 76 [ # # ]: 0 : rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data))); 77 : : }