[CPUFREQ] Cleanup locking in conservative governor
Redesign the locking inside conservative driver. Make dbs_mutex handle all the global state changes inside the driver and invent a new percpu mutex to serialize percpu timer and frequency limit change. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Dave Jones <davej@redhat.com>
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@ -63,7 +63,12 @@ struct cpu_dbs_info_s {
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unsigned int down_skip;
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unsigned int requested_freq;
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int cpu;
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unsigned int enable:1;
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/*
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* percpu mutex that serializes governor limit change with
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* do_dbs_timer invocation. We do not want do_dbs_timer to run
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* when user is changing the governor or limits.
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*/
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struct mutex timer_mutex;
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};
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static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
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@ -71,9 +76,7 @@ static unsigned int dbs_enable; /* number of CPUs using this policy */
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/*
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* dbs_mutex protects data in dbs_tuners_ins from concurrent changes on
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* different CPUs. It protects dbs_enable in governor start/stop. It also
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* serializes governor limit_change with do_dbs_timer. We do not want
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* do_dbs_timer to run when user is changing the governor or limits.
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* different CPUs. It protects dbs_enable in governor start/stop.
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*/
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static DEFINE_MUTEX(dbs_mutex);
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@ -138,9 +141,6 @@ dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
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struct cpufreq_policy *policy;
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if (!this_dbs_info->enable)
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return 0;
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policy = this_dbs_info->cur_policy;
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/*
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@ -483,17 +483,12 @@ static void do_dbs_timer(struct work_struct *work)
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delay -= jiffies % delay;
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mutex_lock(&dbs_mutex);
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if (!dbs_info->enable) {
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mutex_unlock(&dbs_mutex);
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return;
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}
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mutex_lock(&dbs_info->timer_mutex);
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dbs_check_cpu(dbs_info);
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queue_delayed_work_on(cpu, kconservative_wq, &dbs_info->work, delay);
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mutex_unlock(&dbs_mutex);
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mutex_unlock(&dbs_info->timer_mutex);
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}
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static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
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@ -502,7 +497,6 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
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int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
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delay -= jiffies % delay;
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dbs_info->enable = 1;
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INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
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queue_delayed_work_on(dbs_info->cpu, kconservative_wq, &dbs_info->work,
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delay);
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@ -510,7 +504,6 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
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static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
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{
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dbs_info->enable = 0;
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cancel_delayed_work_sync(&dbs_info->work);
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}
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@ -529,9 +522,6 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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if ((!cpu_online(cpu)) || (!policy->cur))
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return -EINVAL;
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if (this_dbs_info->enable) /* Already enabled */
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break;
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mutex_lock(&dbs_mutex);
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rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
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@ -555,6 +545,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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this_dbs_info->down_skip = 0;
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this_dbs_info->requested_freq = policy->cur;
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mutex_init(&this_dbs_info->timer_mutex);
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dbs_enable++;
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/*
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* Start the timerschedule work, when this governor
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@ -596,6 +587,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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mutex_lock(&dbs_mutex);
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sysfs_remove_group(&policy->kobj, &dbs_attr_group);
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dbs_enable--;
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mutex_destroy(&this_dbs_info->timer_mutex);
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/*
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* Stop the timerschedule work, when this governor
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@ -611,7 +603,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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break;
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case CPUFREQ_GOV_LIMITS:
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mutex_lock(&dbs_mutex);
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mutex_lock(&this_dbs_info->timer_mutex);
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if (policy->max < this_dbs_info->cur_policy->cur)
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__cpufreq_driver_target(
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this_dbs_info->cur_policy,
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@ -620,7 +612,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
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__cpufreq_driver_target(
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this_dbs_info->cur_policy,
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policy->min, CPUFREQ_RELATION_L);
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mutex_unlock(&dbs_mutex);
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mutex_unlock(&this_dbs_info->timer_mutex);
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break;
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}
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