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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * drivers/cpufreq/cpufreq_governor.c
  *
  * CPUFREQ governors common code
  *
  * Copyright    (C) 2001 Russell King
  *      (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
  *      (C) 2003 Jun Nakajima <jun.nakajima@intel.com>
  *      (C) 2009 Alexander Clouter <alex@digriz.org.uk>
  *      (c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/export.h>
 #include <linux/kernel_stat.h>
 #include <linux/slab.h>
 
 #include "cpufreq_governor.h"
 
 #define CPUFREQ_DBS_MIN_SAMPLING_INTERVAL   (2 * TICK_NSEC / NSEC_PER_USEC)
 
 static DEFINE_PER_CPU(struct cpu_dbs_info, cpu_dbs);
 
 static DEFINE_MUTEX(gov_dbs_data_mutex);
 
 /* Common sysfs tunables */
 /*
  * sampling_rate_store - update sampling rate effective immediately if needed.
  *
  * If new rate is smaller than the old, simply updating
  * dbs.sampling_rate might not be appropriate. For example, if the
  * original sampling_rate was 1 second and the requested new sampling rate is 10
  * ms because the user needs immediate reaction from ondemand governor, but not
  * sure if higher frequency will be required or not, then, the governor may
  * change the sampling rate too late; up to 1 second later. Thus, if we are
  * reducing the sampling rate, we need to make the new value effective
  * immediately.
  *
  * This must be called with dbs_data->mutex held, otherwise traversing
  * policy_dbs_list isn't safe.
  */
 ssize_t sampling_rate_store(struct gov_attr_set *attr_set, const char *buf,
                 size_t count)
 {
     struct dbs_data *dbs_data = to_dbs_data(attr_set);
     struct policy_dbs_info *policy_dbs;
     unsigned int sampling_interval;
     int ret;
 
     ret = sscanf(buf, "%u", &sampling_interval);
     if (ret != 1 || sampling_interval < CPUFREQ_DBS_MIN_SAMPLING_INTERVAL)
         return -EINVAL;
 
     dbs_data->sampling_rate = sampling_interval;
 
     /*
      * We are operating under dbs_data->mutex and so the list and its
      * entries can't be freed concurrently.
      */
     list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
         mutex_lock(&policy_dbs->update_mutex);
         /*
          * On 32-bit architectures this may race with the
          * sample_delay_ns read in dbs_update_util_handler(), but that
          * really doesn't matter.  If the read returns a value that's
          * too big, the sample will be skipped, but the next invocation
          * of dbs_update_util_handler() (when the update has been
          * completed) will take a sample.
          *
          * If this runs in parallel with dbs_work_handler(), we may end
          * up overwriting the sample_delay_ns value that it has just
          * written, but it will be corrected next time a sample is
          * taken, so it shouldn't be significant.
          */
         gov_update_sample_delay(policy_dbs, 0);
         mutex_unlock(&policy_dbs->update_mutex);
     }
 
     return count;
 }
 EXPORT_SYMBOL_GPL(sampling_rate_store);
 
 /**
  * gov_update_cpu_data - Update CPU load data.
  * @dbs_data: Top-level governor data pointer.
  *
  * Update CPU load data for all CPUs in the domain governed by @dbs_data
  * (that may be a single policy or a bunch of them if governor tunables are
  * system-wide).
  *
  * Call under the @dbs_data mutex.
  */
 void gov_update_cpu_data(struct dbs_data *dbs_data)
 {
     struct policy_dbs_info *policy_dbs;
 
     list_for_each_entry(policy_dbs, &dbs_data->attr_set.policy_list, list) {
         unsigned int j;
 
         for_each_cpu(j, policy_dbs->policy->cpus) {
             struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
 
             j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_update_time,
                                   dbs_data->io_is_busy);
             if (dbs_data->ignore_nice_load)
                 j_cdbs->prev_cpu_nice = kcpustat_field(&kcpustat_cpu(j), CPUTIME_NICE, j);
         }
     }
 }
 EXPORT_SYMBOL_GPL(gov_update_cpu_data);
 
 unsigned int dbs_update(struct cpufreq_policy *policy)
 {
     struct policy_dbs_info *policy_dbs = policy->governor_data;
     struct dbs_data *dbs_data = policy_dbs->dbs_data;
     unsigned int ignore_nice = dbs_data->ignore_nice_load;
     unsigned int max_load = 0, idle_periods = UINT_MAX;
     unsigned int sampling_rate, io_busy, j;
 
     /*
      * Sometimes governors may use an additional multiplier to increase
      * sample delays temporarily.  Apply that multiplier to sampling_rate
      * so as to keep the wake-up-from-idle detection logic a bit
      * conservative.
      */
     sampling_rate = dbs_data->sampling_rate * policy_dbs->rate_mult;
     /*
      * For the purpose of ondemand, waiting for disk IO is an indication
      * that you're performance critical, and not that the system is actually
      * idle, so do not add the iowait time to the CPU idle time then.
      */
     io_busy = dbs_data->io_is_busy;
 
     /* Get Absolute Load */
     for_each_cpu(j, policy->cpus) {
         struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
         u64 update_time, cur_idle_time;
         unsigned int idle_time, time_elapsed;
         unsigned int load;
 
         cur_idle_time = get_cpu_idle_time(j, &update_time, io_busy);
 
         time_elapsed = update_time - j_cdbs->prev_update_time;
         j_cdbs->prev_update_time = update_time;
 
         idle_time = cur_idle_time - j_cdbs->prev_cpu_idle;
         j_cdbs->prev_cpu_idle = cur_idle_time;
 
         if (ignore_nice) {
             u64 cur_nice = kcpustat_field(&kcpustat_cpu(j), CPUTIME_NICE, j);
 
             idle_time += div_u64(cur_nice - j_cdbs->prev_cpu_nice, NSEC_PER_USEC);
             j_cdbs->prev_cpu_nice = cur_nice;
         }
 
         if (unlikely(!time_elapsed)) {
             /*
              * That can only happen when this function is called
              * twice in a row with a very short interval between the
              * calls, so the previous load value can be used then.
              */
             load = j_cdbs->prev_load;
         } else if (unlikely((int)idle_time > 2 * sampling_rate &&
                     j_cdbs->prev_load)) {
             /*
              * If the CPU had gone completely idle and a task has
              * just woken up on this CPU now, it would be unfair to
              * calculate 'load' the usual way for this elapsed
              * time-window, because it would show near-zero load,
              * irrespective of how CPU intensive that task actually
              * was. This is undesirable for latency-sensitive bursty
              * workloads.
              *
              * To avoid this, reuse the 'load' from the previous
              * time-window and give this task a chance to start with
              * a reasonably high CPU frequency. However, that
              * shouldn't be over-done, lest we get stuck at a high
              * load (high frequency) for too long, even when the
              * current system load has actually dropped down, so
              * clear prev_load to guarantee that the load will be
              * computed again next time.
              *
              * Detecting this situation is easy: an unusually large
              * 'idle_time' (as compared to the sampling rate)
              * indicates this scenario.
              */
             load = j_cdbs->prev_load;
             j_cdbs->prev_load = 0;
         } else {
             if (time_elapsed >= idle_time) {
                 load = 100 * (time_elapsed - idle_time) / time_elapsed;
             } else {
                 /*
                  * That can happen if idle_time is returned by
                  * get_cpu_idle_time_jiffy().  In that case
                  * idle_time is roughly equal to the difference
                  * between time_elapsed and "busy time" obtained
                  * from CPU statistics.  Then, the "busy time"
                  * can end up being greater than time_elapsed
                  * (for example, if jiffies_64 and the CPU
                  * statistics are updated by different CPUs),
                  * so idle_time may in fact be negative.  That
                  * means, though, that the CPU was busy all
                  * the time (on the rough average) during the
                  * last sampling interval and 100 can be
                  * returned as the load.
                  */
                 load = (int)idle_time < 0 ? 100 : 0;
             }
             j_cdbs->prev_load = load;
         }
 
         if (unlikely((int)idle_time > 2 * sampling_rate)) {
             unsigned int periods = idle_time / sampling_rate;
 
             if (periods < idle_periods)
                 idle_periods = periods;
         }
 
         if (load > max_load)
             max_load = load;
     }
 
     policy_dbs->idle_periods = idle_periods;
 
     return max_load;
 }
 EXPORT_SYMBOL_GPL(dbs_update);
 
 static void dbs_work_handler(struct work_struct *work)
 {
     struct policy_dbs_info *policy_dbs;
     struct cpufreq_policy *policy;
     struct dbs_governor *gov;
 
     policy_dbs = container_of(work, struct policy_dbs_info, work);
     policy = policy_dbs->policy;
     gov = dbs_governor_of(policy);
 
     /*
      * Make sure cpufreq_governor_limits() isn't evaluating load or the
      * ondemand governor isn't updating the sampling rate in parallel.
      */
     mutex_lock(&policy_dbs->update_mutex);
     gov_update_sample_delay(policy_dbs, gov->gov_dbs_update(policy));
     mutex_unlock(&policy_dbs->update_mutex);
 
     /* Allow the utilization update handler to queue up more work. */
     atomic_set(&policy_dbs->work_count, 0);
     /*
      * If the update below is reordered with respect to the sample delay
      * modification, the utilization update handler may end up using a stale
      * sample delay value.
      */
     smp_wmb();
     policy_dbs->work_in_progress = false;
 }
 
 static void dbs_irq_work(struct irq_work *irq_work)
 {
     struct policy_dbs_info *policy_dbs;
 
     policy_dbs = container_of(irq_work, struct policy_dbs_info, irq_work);
     schedule_work_on(smp_processor_id(), &policy_dbs->work);
 }
 
 static void dbs_update_util_handler(struct update_util_data *data, u64 time,
                     unsigned int flags)
 {
     struct cpu_dbs_info *cdbs = container_of(data, struct cpu_dbs_info, update_util);
     struct policy_dbs_info *policy_dbs = cdbs->policy_dbs;
     u64 delta_ns, lst;
 
     if (!cpufreq_this_cpu_can_update(policy_dbs->policy))
         return;
 
     /*
      * The work may not be allowed to be queued up right now.
      * Possible reasons:
      * - Work has already been queued up or is in progress.
      * - It is too early (too little time from the previous sample).
      */
     if (policy_dbs->work_in_progress)
         return;
 
     /*
      * If the reads below are reordered before the check above, the value
      * of sample_delay_ns used in the computation may be stale.
      */
     smp_rmb();
     lst = READ_ONCE(policy_dbs->last_sample_time);
     delta_ns = time - lst;
     if ((s64)delta_ns < policy_dbs->sample_delay_ns)
         return;
 
     /*
      * If the policy is not shared, the irq_work may be queued up right away
      * at this point.  Otherwise, we need to ensure that only one of the
      * CPUs sharing the policy will do that.
      */
     if (policy_dbs->is_shared) {
         if (!atomic_add_unless(&policy_dbs->work_count, 1, 1))
             return;
 
         /*
          * If another CPU updated last_sample_time in the meantime, we
          * shouldn't be here, so clear the work counter and bail out.
          */
         if (unlikely(lst != READ_ONCE(policy_dbs->last_sample_time))) {
             atomic_set(&policy_dbs->work_count, 0);
             return;
         }
     }
 
     policy_dbs->last_sample_time = time;
     policy_dbs->work_in_progress = true;
     irq_work_queue(&policy_dbs->irq_work);
 }
 
 static void gov_set_update_util(struct policy_dbs_info *policy_dbs,
                 unsigned int delay_us)
 {
     struct cpufreq_policy *policy = policy_dbs->policy;
     int cpu;
 
     gov_update_sample_delay(policy_dbs, delay_us);
     policy_dbs->last_sample_time = 0;
 
     for_each_cpu(cpu, policy->cpus) {
         struct cpu_dbs_info *cdbs = &per_cpu(cpu_dbs, cpu);
 
         cpufreq_add_update_util_hook(cpu, &cdbs->update_util,
                          dbs_update_util_handler);
     }
 }
 
 static inline void gov_clear_update_util(struct cpufreq_policy *policy)
 {
     int i;
 
     for_each_cpu(i, policy->cpus)
         cpufreq_remove_update_util_hook(i);
 
     synchronize_rcu();
 }
 
 static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *policy,
                              struct dbs_governor *gov)
 {
     struct policy_dbs_info *policy_dbs;
     int j;
 
     /* Allocate memory for per-policy governor data. */
     policy_dbs = gov->alloc();
     if (!policy_dbs)
         return NULL;
 
     policy_dbs->policy = policy;
     mutex_init(&policy_dbs->update_mutex);
     atomic_set(&policy_dbs->work_count, 0);
     init_irq_work(&policy_dbs->irq_work, dbs_irq_work);
     INIT_WORK(&policy_dbs->work, dbs_work_handler);
 
     /* Set policy_dbs for all CPUs, online+offline */
     for_each_cpu(j, policy->related_cpus) {
         struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
 
         j_cdbs->policy_dbs = policy_dbs;
     }
     return policy_dbs;
 }
 
 static void free_policy_dbs_info(struct policy_dbs_info *policy_dbs,
                  struct dbs_governor *gov)
 {
     int j;
 
     mutex_destroy(&policy_dbs->update_mutex);
 
     for_each_cpu(j, policy_dbs->policy->related_cpus) {
         struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
 
         j_cdbs->policy_dbs = NULL;
         j_cdbs->update_util.func = NULL;
     }
     gov->free(policy_dbs);
 }
 
 static void cpufreq_dbs_data_release(struct kobject *kobj)
 {
     struct dbs_data *dbs_data = to_dbs_data(to_gov_attr_set(kobj));
     struct dbs_governor *gov = dbs_data->gov;
 
     gov->exit(dbs_data);
     kfree(dbs_data);
 }
 
 int cpufreq_dbs_governor_init(struct cpufreq_policy *policy)
 {
     struct dbs_governor *gov = dbs_governor_of(policy);
     struct dbs_data *dbs_data;
     struct policy_dbs_info *policy_dbs;
     int ret = 0;
 
     /* State should be equivalent to EXIT */
     if (policy->governor_data)
         return -EBUSY;
 
     policy_dbs = alloc_policy_dbs_info(policy, gov);
     if (!policy_dbs)
         return -ENOMEM;
 
     /* Protect gov->gdbs_data against concurrent updates. */
     mutex_lock(&gov_dbs_data_mutex);
 
     dbs_data = gov->gdbs_data;
     if (dbs_data) {
         if (WARN_ON(have_governor_per_policy())) {
             ret = -EINVAL;
             goto free_policy_dbs_info;
         }
         policy_dbs->dbs_data = dbs_data;
         policy->governor_data = policy_dbs;
 
         gov_attr_set_get(&dbs_data->attr_set, &policy_dbs->list);
         goto out;
     }
 
     dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
     if (!dbs_data) {
         ret = -ENOMEM;
         goto free_policy_dbs_info;
     }
 
     dbs_data->gov = gov;
     gov_attr_set_init(&dbs_data->attr_set, &policy_dbs->list);
 
     ret = gov->init(dbs_data);
     if (ret)
         goto free_policy_dbs_info;
 
     /*
      * The sampling interval should not be less than the transition latency
      * of the CPU and it also cannot be too small for dbs_update() to work
      * correctly.
      */
     dbs_data->sampling_rate = max_t(unsigned int,
                     CPUFREQ_DBS_MIN_SAMPLING_INTERVAL,
                     cpufreq_policy_transition_delay_us(policy));
 
     if (!have_governor_per_policy())
         gov->gdbs_data = dbs_data;
 
     policy_dbs->dbs_data = dbs_data;
     policy->governor_data = policy_dbs;
 
     gov->kobj_type.sysfs_ops = &governor_sysfs_ops;
     gov->kobj_type.release = cpufreq_dbs_data_release;
     ret = kobject_init_and_add(&dbs_data->attr_set.kobj, &gov->kobj_type,
                    get_governor_parent_kobj(policy),
                    "%s", gov->gov.name);
     if (!ret)
         goto out;
 
     /* Failure, so roll back. */
     pr_err("initialization failed (dbs_data kobject init error %d)\n", ret);
 
     kobject_put(&dbs_data->attr_set.kobj);
 
     policy->governor_data = NULL;
 
     if (!have_governor_per_policy())
         gov->gdbs_data = NULL;
     gov->exit(dbs_data);
     kfree(dbs_data);
 
 free_policy_dbs_info:
     free_policy_dbs_info(policy_dbs, gov);
 
 out:
     mutex_unlock(&gov_dbs_data_mutex);
     return ret;
 }
 EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_init);
 
 void cpufreq_dbs_governor_exit(struct cpufreq_policy *policy)
 {
     struct dbs_governor *gov = dbs_governor_of(policy);
     struct policy_dbs_info *policy_dbs = policy->governor_data;
     struct dbs_data *dbs_data = policy_dbs->dbs_data;
     unsigned int count;
 
     /* Protect gov->gdbs_data against concurrent updates. */
     mutex_lock(&gov_dbs_data_mutex);
 
     count = gov_attr_set_put(&dbs_data->attr_set, &policy_dbs->list);
 
     policy->governor_data = NULL;
 
     if (!count && !have_governor_per_policy())
         gov->gdbs_data = NULL;
 
     free_policy_dbs_info(policy_dbs, gov);
 
     mutex_unlock(&gov_dbs_data_mutex);
 }
 EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_exit);
 
 int cpufreq_dbs_governor_start(struct cpufreq_policy *policy)
 {
     struct dbs_governor *gov = dbs_governor_of(policy);
     struct policy_dbs_info *policy_dbs = policy->governor_data;
     struct dbs_data *dbs_data = policy_dbs->dbs_data;
     unsigned int sampling_rate, ignore_nice, j;
     unsigned int io_busy;
 
     if (!policy->cur)
         return -EINVAL;
 
     policy_dbs->is_shared = policy_is_shared(policy);
     policy_dbs->rate_mult = 1;
 
     sampling_rate = dbs_data->sampling_rate;
     ignore_nice = dbs_data->ignore_nice_load;
     io_busy = dbs_data->io_is_busy;
 
     for_each_cpu(j, policy->cpus) {
         struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
 
         j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_update_time, io_busy);
         /*
          * Make the first invocation of dbs_update() compute the load.
          */
         j_cdbs->prev_load = 0;
 
         if (ignore_nice)
             j_cdbs->prev_cpu_nice = kcpustat_field(&kcpustat_cpu(j), CPUTIME_NICE, j);
     }
 
     gov->start(policy);
 
     gov_set_update_util(policy_dbs, sampling_rate);
     return 0;
 }
 EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_start);
 
 void cpufreq_dbs_governor_stop(struct cpufreq_policy *policy)
 {
     struct policy_dbs_info *policy_dbs = policy->governor_data;
 
     gov_clear_update_util(policy_dbs->policy);
     irq_work_sync(&policy_dbs->irq_work);
     cancel_work_sync(&policy_dbs->work);
     atomic_set(&policy_dbs->work_count, 0);
     policy_dbs->work_in_progress = false;
 }
 EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop);
 
 void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy)
 {
     struct policy_dbs_info *policy_dbs;
 
     /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit() */
     mutex_lock(&gov_dbs_data_mutex);
     policy_dbs = policy->governor_data;
     if (!policy_dbs)
         goto out;
 
     mutex_lock(&policy_dbs->update_mutex);
     cpufreq_policy_apply_limits(policy);
     gov_update_sample_delay(policy_dbs, 0);
     mutex_unlock(&policy_dbs->update_mutex);
 
 out:
     mutex_unlock(&gov_dbs_data_mutex);
 }
 EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);

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