LCOV - code coverage report
Current view: top level - drivers/cpufreq - cpufreq_governor.c (source / functions) Hit Total Coverage
Test: gcov_data_raspi2_real_modules_combined.info Lines: 124 185 67.0 %
Date: 2020-09-30 20:25:40 Functions: 10 15 66.7 %
Branches: 49 86 57.0 %

           Branch data     Line data    Source code
       1                 :            : // SPDX-License-Identifier: GPL-2.0-only
       2                 :            : /*
       3                 :            :  * drivers/cpufreq/cpufreq_governor.c
       4                 :            :  *
       5                 :            :  * CPUFREQ governors common code
       6                 :            :  *
       7                 :            :  * Copyright    (C) 2001 Russell King
       8                 :            :  *              (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
       9                 :            :  *              (C) 2003 Jun Nakajima <jun.nakajima@intel.com>
      10                 :            :  *              (C) 2009 Alexander Clouter <alex@digriz.org.uk>
      11                 :            :  *              (c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
      12                 :            :  */
      13                 :            : 
      14                 :            : #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      15                 :            : 
      16                 :            : #include <linux/export.h>
      17                 :            : #include <linux/kernel_stat.h>
      18                 :            : #include <linux/slab.h>
      19                 :            : 
      20                 :            : #include "cpufreq_governor.h"
      21                 :            : 
      22                 :            : #define CPUFREQ_DBS_MIN_SAMPLING_INTERVAL       (2 * TICK_NSEC / NSEC_PER_USEC)
      23                 :            : 
      24                 :            : static DEFINE_PER_CPU(struct cpu_dbs_info, cpu_dbs);
      25                 :            : 
      26                 :            : static DEFINE_MUTEX(gov_dbs_data_mutex);
      27                 :            : 
      28                 :            : /* Common sysfs tunables */
      29                 :            : /**
      30                 :            :  * store_sampling_rate - update sampling rate effective immediately if needed.
      31                 :            :  *
      32                 :            :  * If new rate is smaller than the old, simply updating
      33                 :            :  * dbs.sampling_rate might not be appropriate. For example, if the
      34                 :            :  * original sampling_rate was 1 second and the requested new sampling rate is 10
      35                 :            :  * ms because the user needs immediate reaction from ondemand governor, but not
      36                 :            :  * sure if higher frequency will be required or not, then, the governor may
      37                 :            :  * change the sampling rate too late; up to 1 second later. Thus, if we are
      38                 :            :  * reducing the sampling rate, we need to make the new value effective
      39                 :            :  * immediately.
      40                 :            :  *
      41                 :            :  * This must be called with dbs_data->mutex held, otherwise traversing
      42                 :            :  * policy_dbs_list isn't safe.
      43                 :            :  */
      44                 :        207 : ssize_t store_sampling_rate(struct gov_attr_set *attr_set, const char *buf,
      45                 :            :                             size_t count)
      46                 :            : {
      47                 :            :         struct dbs_data *dbs_data = to_dbs_data(attr_set);
      48                 :            :         struct policy_dbs_info *policy_dbs;
      49                 :            :         unsigned int sampling_interval;
      50                 :            :         int ret;
      51                 :            : 
      52                 :        207 :         ret = sscanf(buf, "%u", &sampling_interval);
      53   [ +  -  +  - ]:        207 :         if (ret != 1 || sampling_interval < CPUFREQ_DBS_MIN_SAMPLING_INTERVAL)
      54                 :            :                 return -EINVAL;
      55                 :            : 
      56                 :        207 :         dbs_data->sampling_rate = sampling_interval;
      57                 :            : 
      58                 :            :         /*
      59                 :            :          * We are operating under dbs_data->mutex and so the list and its
      60                 :            :          * entries can't be freed concurrently.
      61                 :            :          */
      62         [ +  + ]:        414 :         list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
      63                 :        207 :                 mutex_lock(&policy_dbs->update_mutex);
      64                 :            :                 /*
      65                 :            :                  * On 32-bit architectures this may race with the
      66                 :            :                  * sample_delay_ns read in dbs_update_util_handler(), but that
      67                 :            :                  * really doesn't matter.  If the read returns a value that's
      68                 :            :                  * too big, the sample will be skipped, but the next invocation
      69                 :            :                  * of dbs_update_util_handler() (when the update has been
      70                 :            :                  * completed) will take a sample.
      71                 :            :                  *
      72                 :            :                  * If this runs in parallel with dbs_work_handler(), we may end
      73                 :            :                  * up overwriting the sample_delay_ns value that it has just
      74                 :            :                  * written, but it will be corrected next time a sample is
      75                 :            :                  * taken, so it shouldn't be significant.
      76                 :            :                  */
      77                 :            :                 gov_update_sample_delay(policy_dbs, 0);
      78                 :        207 :                 mutex_unlock(&policy_dbs->update_mutex);
      79                 :            :         }
      80                 :            : 
      81                 :        207 :         return count;
      82                 :            : }
      83                 :            : EXPORT_SYMBOL_GPL(store_sampling_rate);
      84                 :            : 
      85                 :            : /**
      86                 :            :  * gov_update_cpu_data - Update CPU load data.
      87                 :            :  * @dbs_data: Top-level governor data pointer.
      88                 :            :  *
      89                 :            :  * Update CPU load data for all CPUs in the domain governed by @dbs_data
      90                 :            :  * (that may be a single policy or a bunch of them if governor tunables are
      91                 :            :  * system-wide).
      92                 :            :  *
      93                 :            :  * Call under the @dbs_data mutex.
      94                 :            :  */
      95                 :          0 : void gov_update_cpu_data(struct dbs_data *dbs_data)
      96                 :            : {
      97                 :            :         struct policy_dbs_info *policy_dbs;
      98                 :            : 
      99         [ #  # ]:          0 :         list_for_each_entry(policy_dbs, &dbs_data->attr_set.policy_list, list) {
     100                 :            :                 unsigned int j;
     101                 :            : 
     102         [ #  # ]:          0 :                 for_each_cpu(j, policy_dbs->policy->cpus) {
     103                 :          0 :                         struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
     104                 :            : 
     105                 :          0 :                         j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_update_time,
     106                 :          0 :                                                                   dbs_data->io_is_busy);
     107         [ #  # ]:          0 :                         if (dbs_data->ignore_nice_load)
     108                 :          0 :                                 j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
     109                 :            :                 }
     110                 :            :         }
     111                 :          0 : }
     112                 :            : EXPORT_SYMBOL_GPL(gov_update_cpu_data);
     113                 :            : 
     114                 :     111085 : unsigned int dbs_update(struct cpufreq_policy *policy)
     115                 :            : {
     116                 :     111085 :         struct policy_dbs_info *policy_dbs = policy->governor_data;
     117                 :     111085 :         struct dbs_data *dbs_data = policy_dbs->dbs_data;
     118                 :     111085 :         unsigned int ignore_nice = dbs_data->ignore_nice_load;
     119                 :            :         unsigned int max_load = 0, idle_periods = UINT_MAX;
     120                 :            :         unsigned int sampling_rate, io_busy, j;
     121                 :            : 
     122                 :            :         /*
     123                 :            :          * Sometimes governors may use an additional multiplier to increase
     124                 :            :          * sample delays temporarily.  Apply that multiplier to sampling_rate
     125                 :            :          * so as to keep the wake-up-from-idle detection logic a bit
     126                 :            :          * conservative.
     127                 :            :          */
     128                 :     111085 :         sampling_rate = dbs_data->sampling_rate * policy_dbs->rate_mult;
     129                 :            :         /*
     130                 :            :          * For the purpose of ondemand, waiting for disk IO is an indication
     131                 :            :          * that you're performance critical, and not that the system is actually
     132                 :            :          * idle, so do not add the iowait time to the CPU idle time then.
     133                 :            :          */
     134                 :     111085 :         io_busy = dbs_data->io_is_busy;
     135                 :            : 
     136                 :            :         /* Get Absolute Load */
     137         [ +  + ]:     666510 :         for_each_cpu(j, policy->cpus) {
     138                 :     444340 :                 struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
     139                 :            :                 u64 update_time, cur_idle_time;
     140                 :            :                 unsigned int idle_time, time_elapsed;
     141                 :            :                 unsigned int load;
     142                 :            : 
     143                 :     444340 :                 cur_idle_time = get_cpu_idle_time(j, &update_time, io_busy);
     144                 :            : 
     145                 :     444340 :                 time_elapsed = update_time - j_cdbs->prev_update_time;
     146                 :     444340 :                 j_cdbs->prev_update_time = update_time;
     147                 :            : 
     148                 :     444340 :                 idle_time = cur_idle_time - j_cdbs->prev_cpu_idle;
     149                 :     444340 :                 j_cdbs->prev_cpu_idle = cur_idle_time;
     150                 :            : 
     151         [ -  + ]:     444340 :                 if (ignore_nice) {
     152                 :          0 :                         u64 cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
     153                 :            : 
     154                 :          0 :                         idle_time += div_u64(cur_nice - j_cdbs->prev_cpu_nice, NSEC_PER_USEC);
     155                 :          0 :                         j_cdbs->prev_cpu_nice = cur_nice;
     156                 :            :                 }
     157                 :            : 
     158         [ -  + ]:     444340 :                 if (unlikely(!time_elapsed)) {
     159                 :            :                         /*
     160                 :            :                          * That can only happen when this function is called
     161                 :            :                          * twice in a row with a very short interval between the
     162                 :            :                          * calls, so the previous load value can be used then.
     163                 :            :                          */
     164                 :          0 :                         load = j_cdbs->prev_load;
     165   [ +  +  +  + ]:     444340 :                 } else if (unlikely((int)idle_time > 2 * sampling_rate &&
     166                 :            :                                     j_cdbs->prev_load)) {
     167                 :            :                         /*
     168                 :            :                          * If the CPU had gone completely idle and a task has
     169                 :            :                          * just woken up on this CPU now, it would be unfair to
     170                 :            :                          * calculate 'load' the usual way for this elapsed
     171                 :            :                          * time-window, because it would show near-zero load,
     172                 :            :                          * irrespective of how CPU intensive that task actually
     173                 :            :                          * was. This is undesirable for latency-sensitive bursty
     174                 :            :                          * workloads.
     175                 :            :                          *
     176                 :            :                          * To avoid this, reuse the 'load' from the previous
     177                 :            :                          * time-window and give this task a chance to start with
     178                 :            :                          * a reasonably high CPU frequency. However, that
     179                 :            :                          * shouldn't be over-done, lest we get stuck at a high
     180                 :            :                          * load (high frequency) for too long, even when the
     181                 :            :                          * current system load has actually dropped down, so
     182                 :            :                          * clear prev_load to guarantee that the load will be
     183                 :            :                          * computed again next time.
     184                 :            :                          *
     185                 :            :                          * Detecting this situation is easy: an unusually large
     186                 :            :                          * 'idle_time' (as compared to the sampling rate)
     187                 :            :                          * indicates this scenario.
     188                 :            :                          */
     189                 :            :                         load = j_cdbs->prev_load;
     190                 :        294 :                         j_cdbs->prev_load = 0;
     191                 :            :                 } else {
     192         [ +  + ]:     444046 :                         if (time_elapsed >= idle_time) {
     193                 :     428237 :                                 load = 100 * (time_elapsed - idle_time) / time_elapsed;
     194                 :            :                         } else {
     195                 :            :                                 /*
     196                 :            :                                  * That can happen if idle_time is returned by
     197                 :            :                                  * get_cpu_idle_time_jiffy().  In that case
     198                 :            :                                  * idle_time is roughly equal to the difference
     199                 :            :                                  * between time_elapsed and "busy time" obtained
     200                 :            :                                  * from CPU statistics.  Then, the "busy time"
     201                 :            :                                  * can end up being greater than time_elapsed
     202                 :            :                                  * (for example, if jiffies_64 and the CPU
     203                 :            :                                  * statistics are updated by different CPUs),
     204                 :            :                                  * so idle_time may in fact be negative.  That
     205                 :            :                                  * means, though, that the CPU was busy all
     206                 :            :                                  * the time (on the rough average) during the
     207                 :            :                                  * last sampling interval and 100 can be
     208                 :            :                                  * returned as the load.
     209                 :            :                                  */
     210         [ +  - ]:      15809 :                                 load = (int)idle_time < 0 ? 100 : 0;
     211                 :            :                         }
     212                 :     444046 :                         j_cdbs->prev_load = load;
     213                 :            :                 }
     214                 :            : 
     215         [ +  + ]:     444340 :                 if (unlikely((int)idle_time > 2 * sampling_rate)) {
     216                 :       2151 :                         unsigned int periods = idle_time / sampling_rate;
     217                 :            : 
     218         [ +  + ]:       2151 :                         if (periods < idle_periods)
     219                 :            :                                 idle_periods = periods;
     220                 :            :                 }
     221                 :            : 
     222         [ +  + ]:     444340 :                 if (load > max_load)
     223                 :            :                         max_load = load;
     224                 :            :         }
     225                 :            : 
     226                 :     111085 :         policy_dbs->idle_periods = idle_periods;
     227                 :            : 
     228                 :     111085 :         return max_load;
     229                 :            : }
     230                 :            : EXPORT_SYMBOL_GPL(dbs_update);
     231                 :            : 
     232                 :     111085 : static void dbs_work_handler(struct work_struct *work)
     233                 :            : {
     234                 :            :         struct policy_dbs_info *policy_dbs;
     235                 :            :         struct cpufreq_policy *policy;
     236                 :            :         struct dbs_governor *gov;
     237                 :            : 
     238                 :            :         policy_dbs = container_of(work, struct policy_dbs_info, work);
     239                 :     111085 :         policy = policy_dbs->policy;
     240                 :            :         gov = dbs_governor_of(policy);
     241                 :            : 
     242                 :            :         /*
     243                 :            :          * Make sure cpufreq_governor_limits() isn't evaluating load or the
     244                 :            :          * ondemand governor isn't updating the sampling rate in parallel.
     245                 :            :          */
     246                 :     111085 :         mutex_lock(&policy_dbs->update_mutex);
     247                 :     111085 :         gov_update_sample_delay(policy_dbs, gov->gov_dbs_update(policy));
     248                 :     111085 :         mutex_unlock(&policy_dbs->update_mutex);
     249                 :            : 
     250                 :            :         /* Allow the utilization update handler to queue up more work. */
     251                 :            :         atomic_set(&policy_dbs->work_count, 0);
     252                 :            :         /*
     253                 :            :          * If the update below is reordered with respect to the sample delay
     254                 :            :          * modification, the utilization update handler may end up using a stale
     255                 :            :          * sample delay value.
     256                 :            :          */
     257                 :     111085 :         smp_wmb();
     258                 :     111085 :         policy_dbs->work_in_progress = false;
     259                 :     111085 : }
     260                 :            : 
     261                 :     111085 : static void dbs_irq_work(struct irq_work *irq_work)
     262                 :            : {
     263                 :            :         struct policy_dbs_info *policy_dbs;
     264                 :            : 
     265                 :            :         policy_dbs = container_of(irq_work, struct policy_dbs_info, irq_work);
     266                 :     111085 :         schedule_work_on(smp_processor_id(), &policy_dbs->work);
     267                 :     111085 : }
     268                 :            : 
     269                 :   15631174 : static void dbs_update_util_handler(struct update_util_data *data, u64 time,
     270                 :            :                                     unsigned int flags)
     271                 :            : {
     272                 :            :         struct cpu_dbs_info *cdbs = container_of(data, struct cpu_dbs_info, update_util);
     273                 :   15631174 :         struct policy_dbs_info *policy_dbs = cdbs->policy_dbs;
     274                 :            :         u64 delta_ns, lst;
     275                 :            : 
     276         [ +  + ]:   15631174 :         if (!cpufreq_this_cpu_can_update(policy_dbs->policy))
     277                 :            :                 return;
     278                 :            : 
     279                 :            :         /*
     280                 :            :          * The work may not be allowed to be queued up right now.
     281                 :            :          * Possible reasons:
     282                 :            :          * - Work has already been queued up or is in progress.
     283                 :            :          * - It is too early (too little time from the previous sample).
     284                 :            :          */
     285         [ +  + ]:   15644416 :         if (policy_dbs->work_in_progress)
     286                 :            :                 return;
     287                 :            : 
     288                 :            :         /*
     289                 :            :          * If the reads below are reordered before the check above, the value
     290                 :            :          * of sample_delay_ns used in the computation may be stale.
     291                 :            :          */
     292                 :   15407823 :         smp_rmb();
     293                 :            :         lst = READ_ONCE(policy_dbs->last_sample_time);
     294                 :   15359311 :         delta_ns = time - lst;
     295         [ +  + ]:   15359311 :         if ((s64)delta_ns < policy_dbs->sample_delay_ns)
     296                 :            :                 return;
     297                 :            : 
     298                 :            :         /*
     299                 :            :          * If the policy is not shared, the irq_work may be queued up right away
     300                 :            :          * at this point.  Otherwise, we need to ensure that only one of the
     301                 :            :          * CPUs sharing the policy will do that.
     302                 :            :          */
     303         [ +  + ]:     116616 :         if (policy_dbs->is_shared) {
     304         [ +  + ]:     231245 :                 if (!atomic_add_unless(&policy_dbs->work_count, 1, 1))
     305                 :            :                         return;
     306                 :            : 
     307                 :            :                 /*
     308                 :            :                  * If another CPU updated last_sample_time in the meantime, we
     309                 :            :                  * shouldn't be here, so clear the work counter and bail out.
     310                 :            :                  */
     311         [ -  + ]:     111085 :                 if (unlikely(lst != READ_ONCE(policy_dbs->last_sample_time))) {
     312                 :            :                         atomic_set(&policy_dbs->work_count, 0);
     313                 :          0 :                         return;
     314                 :            :                 }
     315                 :            :         }
     316                 :            : 
     317                 :     112488 :         policy_dbs->last_sample_time = time;
     318                 :     112488 :         policy_dbs->work_in_progress = true;
     319                 :     112488 :         irq_work_queue(&policy_dbs->irq_work);
     320                 :            : }
     321                 :            : 
     322                 :        207 : static void gov_set_update_util(struct policy_dbs_info *policy_dbs,
     323                 :            :                                 unsigned int delay_us)
     324                 :            : {
     325                 :        207 :         struct cpufreq_policy *policy = policy_dbs->policy;
     326                 :            :         int cpu;
     327                 :            : 
     328                 :            :         gov_update_sample_delay(policy_dbs, delay_us);
     329                 :        207 :         policy_dbs->last_sample_time = 0;
     330                 :            : 
     331         [ +  + ]:       1242 :         for_each_cpu(cpu, policy->cpus) {
     332                 :        828 :                 struct cpu_dbs_info *cdbs = &per_cpu(cpu_dbs, cpu);
     333                 :            : 
     334                 :        828 :                 cpufreq_add_update_util_hook(cpu, &cdbs->update_util,
     335                 :            :                                              dbs_update_util_handler);
     336                 :            :         }
     337                 :        207 : }
     338                 :            : 
     339                 :          0 : static inline void gov_clear_update_util(struct cpufreq_policy *policy)
     340                 :            : {
     341                 :            :         int i;
     342                 :            : 
     343         [ #  # ]:          0 :         for_each_cpu(i, policy->cpus)
     344                 :          0 :                 cpufreq_remove_update_util_hook(i);
     345                 :            : 
     346                 :          0 :         synchronize_rcu();
     347                 :          0 : }
     348                 :            : 
     349                 :        207 : static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *policy,
     350                 :            :                                                      struct dbs_governor *gov)
     351                 :            : {
     352                 :            :         struct policy_dbs_info *policy_dbs;
     353                 :            :         int j;
     354                 :            : 
     355                 :            :         /* Allocate memory for per-policy governor data. */
     356                 :        207 :         policy_dbs = gov->alloc();
     357         [ +  - ]:        207 :         if (!policy_dbs)
     358                 :            :                 return NULL;
     359                 :            : 
     360                 :        207 :         policy_dbs->policy = policy;
     361                 :        207 :         mutex_init(&policy_dbs->update_mutex);
     362                 :            :         atomic_set(&policy_dbs->work_count, 0);
     363                 :            :         init_irq_work(&policy_dbs->irq_work, dbs_irq_work);
     364                 :        414 :         INIT_WORK(&policy_dbs->work, dbs_work_handler);
     365                 :            : 
     366                 :            :         /* Set policy_dbs for all CPUs, online+offline */
     367         [ +  + ]:       1242 :         for_each_cpu(j, policy->related_cpus) {
     368                 :        828 :                 struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
     369                 :            : 
     370                 :        828 :                 j_cdbs->policy_dbs = policy_dbs;
     371                 :            :         }
     372                 :            :         return policy_dbs;
     373                 :            : }
     374                 :            : 
     375                 :          0 : static void free_policy_dbs_info(struct policy_dbs_info *policy_dbs,
     376                 :            :                                  struct dbs_governor *gov)
     377                 :            : {
     378                 :            :         int j;
     379                 :            : 
     380                 :            :         mutex_destroy(&policy_dbs->update_mutex);
     381                 :            : 
     382         [ #  # ]:          0 :         for_each_cpu(j, policy_dbs->policy->related_cpus) {
     383                 :          0 :                 struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
     384                 :            : 
     385                 :          0 :                 j_cdbs->policy_dbs = NULL;
     386                 :          0 :                 j_cdbs->update_util.func = NULL;
     387                 :            :         }
     388                 :          0 :         gov->free(policy_dbs);
     389                 :          0 : }
     390                 :            : 
     391                 :        207 : int cpufreq_dbs_governor_init(struct cpufreq_policy *policy)
     392                 :            : {
     393                 :            :         struct dbs_governor *gov = dbs_governor_of(policy);
     394                 :            :         struct dbs_data *dbs_data;
     395                 :            :         struct policy_dbs_info *policy_dbs;
     396                 :            :         int ret = 0;
     397                 :            : 
     398                 :            :         /* State should be equivalent to EXIT */
     399         [ +  - ]:        207 :         if (policy->governor_data)
     400                 :            :                 return -EBUSY;
     401                 :            : 
     402                 :        207 :         policy_dbs = alloc_policy_dbs_info(policy, gov);
     403         [ +  - ]:        207 :         if (!policy_dbs)
     404                 :            :                 return -ENOMEM;
     405                 :            : 
     406                 :            :         /* Protect gov->gdbs_data against concurrent updates. */
     407                 :        207 :         mutex_lock(&gov_dbs_data_mutex);
     408                 :            : 
     409                 :        207 :         dbs_data = gov->gdbs_data;
     410         [ -  + ]:        207 :         if (dbs_data) {
     411   [ #  #  #  # ]:          0 :                 if (WARN_ON(have_governor_per_policy())) {
     412                 :            :                         ret = -EINVAL;
     413                 :            :                         goto free_policy_dbs_info;
     414                 :            :                 }
     415                 :          0 :                 policy_dbs->dbs_data = dbs_data;
     416                 :          0 :                 policy->governor_data = policy_dbs;
     417                 :            : 
     418                 :          0 :                 gov_attr_set_get(&dbs_data->attr_set, &policy_dbs->list);
     419                 :          0 :                 goto out;
     420                 :            :         }
     421                 :            : 
     422                 :        207 :         dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
     423         [ +  - ]:        207 :         if (!dbs_data) {
     424                 :            :                 ret = -ENOMEM;
     425                 :            :                 goto free_policy_dbs_info;
     426                 :            :         }
     427                 :            : 
     428                 :        207 :         gov_attr_set_init(&dbs_data->attr_set, &policy_dbs->list);
     429                 :            : 
     430                 :        207 :         ret = gov->init(dbs_data);
     431         [ +  - ]:        207 :         if (ret)
     432                 :            :                 goto free_policy_dbs_info;
     433                 :            : 
     434                 :            :         /*
     435                 :            :          * The sampling interval should not be less than the transition latency
     436                 :            :          * of the CPU and it also cannot be too small for dbs_update() to work
     437                 :            :          * correctly.
     438                 :            :          */
     439                 :        207 :         dbs_data->sampling_rate = max_t(unsigned int,
     440                 :            :                                         CPUFREQ_DBS_MIN_SAMPLING_INTERVAL,
     441                 :            :                                         cpufreq_policy_transition_delay_us(policy));
     442                 :            : 
     443         [ +  - ]:        207 :         if (!have_governor_per_policy())
     444                 :        207 :                 gov->gdbs_data = dbs_data;
     445                 :            : 
     446                 :        207 :         policy_dbs->dbs_data = dbs_data;
     447                 :        207 :         policy->governor_data = policy_dbs;
     448                 :            : 
     449                 :        207 :         gov->kobj_type.sysfs_ops = &governor_sysfs_ops;
     450                 :        414 :         ret = kobject_init_and_add(&dbs_data->attr_set.kobj, &gov->kobj_type,
     451                 :            :                                    get_governor_parent_kobj(policy),
     452                 :        207 :                                    "%s", gov->gov.name);
     453         [ -  + ]:        207 :         if (!ret)
     454                 :            :                 goto out;
     455                 :            : 
     456                 :            :         /* Failure, so roll back. */
     457                 :          0 :         pr_err("initialization failed (dbs_data kobject init error %d)\n", ret);
     458                 :            : 
     459                 :          0 :         kobject_put(&dbs_data->attr_set.kobj);
     460                 :            : 
     461                 :          0 :         policy->governor_data = NULL;
     462                 :            : 
     463         [ #  # ]:          0 :         if (!have_governor_per_policy())
     464                 :          0 :                 gov->gdbs_data = NULL;
     465                 :          0 :         gov->exit(dbs_data);
     466                 :          0 :         kfree(dbs_data);
     467                 :            : 
     468                 :            : free_policy_dbs_info:
     469                 :          0 :         free_policy_dbs_info(policy_dbs, gov);
     470                 :            : 
     471                 :            : out:
     472                 :        207 :         mutex_unlock(&gov_dbs_data_mutex);
     473                 :        207 :         return ret;
     474                 :            : }
     475                 :            : EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_init);
     476                 :            : 
     477                 :          0 : void cpufreq_dbs_governor_exit(struct cpufreq_policy *policy)
     478                 :            : {
     479                 :            :         struct dbs_governor *gov = dbs_governor_of(policy);
     480                 :          0 :         struct policy_dbs_info *policy_dbs = policy->governor_data;
     481                 :          0 :         struct dbs_data *dbs_data = policy_dbs->dbs_data;
     482                 :            :         unsigned int count;
     483                 :            : 
     484                 :            :         /* Protect gov->gdbs_data against concurrent updates. */
     485                 :          0 :         mutex_lock(&gov_dbs_data_mutex);
     486                 :            : 
     487                 :          0 :         count = gov_attr_set_put(&dbs_data->attr_set, &policy_dbs->list);
     488                 :            : 
     489                 :          0 :         policy->governor_data = NULL;
     490                 :            : 
     491         [ #  # ]:          0 :         if (!count) {
     492         [ #  # ]:          0 :                 if (!have_governor_per_policy())
     493                 :          0 :                         gov->gdbs_data = NULL;
     494                 :            : 
     495                 :          0 :                 gov->exit(dbs_data);
     496                 :          0 :                 kfree(dbs_data);
     497                 :            :         }
     498                 :            : 
     499                 :          0 :         free_policy_dbs_info(policy_dbs, gov);
     500                 :            : 
     501                 :          0 :         mutex_unlock(&gov_dbs_data_mutex);
     502                 :          0 : }
     503                 :            : EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_exit);
     504                 :            : 
     505                 :        207 : int cpufreq_dbs_governor_start(struct cpufreq_policy *policy)
     506                 :            : {
     507                 :            :         struct dbs_governor *gov = dbs_governor_of(policy);
     508                 :        207 :         struct policy_dbs_info *policy_dbs = policy->governor_data;
     509                 :        207 :         struct dbs_data *dbs_data = policy_dbs->dbs_data;
     510                 :            :         unsigned int sampling_rate, ignore_nice, j;
     511                 :            :         unsigned int io_busy;
     512                 :            : 
     513         [ +  - ]:        207 :         if (!policy->cur)
     514                 :            :                 return -EINVAL;
     515                 :            : 
     516                 :        207 :         policy_dbs->is_shared = policy_is_shared(policy);
     517                 :        207 :         policy_dbs->rate_mult = 1;
     518                 :            : 
     519                 :        207 :         sampling_rate = dbs_data->sampling_rate;
     520                 :        207 :         ignore_nice = dbs_data->ignore_nice_load;
     521                 :        207 :         io_busy = dbs_data->io_is_busy;
     522                 :            : 
     523         [ +  + ]:       1242 :         for_each_cpu(j, policy->cpus) {
     524                 :        828 :                 struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);
     525                 :            : 
     526                 :        828 :                 j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_update_time, io_busy);
     527                 :            :                 /*
     528                 :            :                  * Make the first invocation of dbs_update() compute the load.
     529                 :            :                  */
     530                 :        828 :                 j_cdbs->prev_load = 0;
     531                 :            : 
     532         [ -  + ]:        828 :                 if (ignore_nice)
     533                 :          0 :                         j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
     534                 :            :         }
     535                 :            : 
     536                 :        207 :         gov->start(policy);
     537                 :            : 
     538                 :        207 :         gov_set_update_util(policy_dbs, sampling_rate);
     539                 :        207 :         return 0;
     540                 :            : }
     541                 :            : EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_start);
     542                 :            : 
     543                 :          0 : void cpufreq_dbs_governor_stop(struct cpufreq_policy *policy)
     544                 :            : {
     545                 :          0 :         struct policy_dbs_info *policy_dbs = policy->governor_data;
     546                 :            : 
     547                 :          0 :         gov_clear_update_util(policy_dbs->policy);
     548                 :          0 :         irq_work_sync(&policy_dbs->irq_work);
     549                 :          0 :         cancel_work_sync(&policy_dbs->work);
     550                 :            :         atomic_set(&policy_dbs->work_count, 0);
     551                 :          0 :         policy_dbs->work_in_progress = false;
     552                 :          0 : }
     553                 :            : EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop);
     554                 :            : 
     555                 :        207 : void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy)
     556                 :            : {
     557                 :            :         struct policy_dbs_info *policy_dbs;
     558                 :            : 
     559                 :            :         /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit() */
     560                 :        207 :         mutex_lock(&gov_dbs_data_mutex);
     561                 :        207 :         policy_dbs = policy->governor_data;
     562         [ +  - ]:        207 :         if (!policy_dbs)
     563                 :            :                 goto out;
     564                 :            : 
     565                 :        207 :         mutex_lock(&policy_dbs->update_mutex);
     566                 :        207 :         cpufreq_policy_apply_limits(policy);
     567                 :            :         gov_update_sample_delay(policy_dbs, 0);
     568                 :        207 :         mutex_unlock(&policy_dbs->update_mutex);
     569                 :            : 
     570                 :            : out:
     571                 :        207 :         mutex_unlock(&gov_dbs_data_mutex);
     572                 :        207 : }
     573                 :            : EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);

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