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 10 DEFINE_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 */ 30 void 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 } 43 EXPORT_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 */ 55 void cpufreq_remove_update_util_hook(int cpu) 56 { 57 rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL); 58 } 59 EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook); 60