kernel/sched/cpufreq.c

   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  */
  11
  12 #include "sched.h"
  13
  14 DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
  15
  16 /**
  17  * cpufreq_set_update_util_data - Populate the CPU's update_util_data pointer.
  18  * @cpu: The CPU to set the pointer for.
  19  * @data: New pointer value.
  20  *
  21  * Set and publish the update_util_data pointer for the given CPU.  That pointer
  22  * points to a struct update_util_data object containing a callback function
  23  * to call from cpufreq_update_util().  That function will be called from an RCU
  24  * read-side critical section, so it must not sleep.
  25  *
  26  * Callers must use RCU-sched callbacks to free any memory that might be
  27  * accessed via the old update_util_data pointer or invoke synchronize_sched()
  28  * right after this function to avoid use-after-free.
  29  */
  30 void cpufreq_set_update_util_data(int cpu, struct update_util_data *data)
  31 {
  32         if (WARN_ON(data && !data->func))
  33                 return;
  34
  35         rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
  36 }
  37 EXPORT_SYMBOL_GPL(cpufreq_set_update_util_data);