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Commit ee88415c authored by venkatesh.pallipadi@intel.com's avatar venkatesh.pallipadi@intel.com Committed by Dave Jones
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[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: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
parent 5a75c828

drivers/cpufreq/cpufreq_conservative.c

+13 −21
Original line number Diff line number Diff line
@@ -63,7 +63,12 @@ struct cpu_dbs_info_s { 
	unsigned int down_skip;

	unsigned int requested_freq;

	int cpu;

	unsigned int enable:1;

	/*

	 * percpu mutex that serializes governor limit change with

	 * do_dbs_timer invocation. We do not want do_dbs_timer to run

	 * when user is changing the governor or limits.

	 */

	struct mutex timer_mutex;

};

static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
@@ -71,9 +76,7 @@ static unsigned int dbs_enable; /* number of CPUs using this policy */ 


/*

 * dbs_mutex protects data in dbs_tuners_ins from concurrent changes on

 * different CPUs. It protects dbs_enable in governor start/stop. It also

 * serializes governor limit_change with do_dbs_timer. We do not want

 * do_dbs_timer to run when user is changing the governor or limits.

 * different CPUs. It protects dbs_enable in governor start/stop.

 */

static DEFINE_MUTEX(dbs_mutex);
@@ -138,9 +141,6 @@ dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 


	struct cpufreq_policy *policy;



	if (!this_dbs_info->enable)

		return 0;



	policy = this_dbs_info->cur_policy;



	/*
@@ -483,17 +483,12 @@ static void do_dbs_timer(struct work_struct *work) 


	delay -= jiffies % delay;



	mutex_lock(&dbs_mutex);



	if (!dbs_info->enable) {

		mutex_unlock(&dbs_mutex);

		return;

	}

	mutex_lock(&dbs_info->timer_mutex);



	dbs_check_cpu(dbs_info);



	queue_delayed_work_on(cpu, kconservative_wq, &dbs_info->work, delay);

	mutex_unlock(&dbs_mutex);

	mutex_unlock(&dbs_info->timer_mutex);

}



static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
@@ -502,7 +497,6 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info) 
	int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);

	delay -= jiffies % delay;



	dbs_info->enable = 1;

	INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);

	queue_delayed_work_on(dbs_info->cpu, kconservative_wq, &dbs_info->work,

				delay);
@@ -510,7 +504,6 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info) 


static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)

{

	dbs_info->enable = 0;

	cancel_delayed_work_sync(&dbs_info->work);

}
@@ -529,9 +522,6 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
		if ((!cpu_online(cpu)) || (!policy->cur))

			return -EINVAL;



		if (this_dbs_info->enable) /* Already enabled */

			break;



		mutex_lock(&dbs_mutex);



		rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
@@ -555,6 +545,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
		this_dbs_info->down_skip = 0;

		this_dbs_info->requested_freq = policy->cur;



		mutex_init(&this_dbs_info->timer_mutex);

		dbs_enable++;

		/*

		 * Start the timerschedule work, when this governor
@@ -596,6 +587,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
		mutex_lock(&dbs_mutex);

		sysfs_remove_group(&policy->kobj, &dbs_attr_group);

		dbs_enable--;

		mutex_destroy(&this_dbs_info->timer_mutex);



		/*

		 * Stop the timerschedule work, when this governor
@@ -611,7 +603,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
		break;



	case CPUFREQ_GOV_LIMITS:

		mutex_lock(&dbs_mutex);

		mutex_lock(&this_dbs_info->timer_mutex);

		if (policy->max < this_dbs_info->cur_policy->cur)

			__cpufreq_driver_target(

					this_dbs_info->cur_policy,
@@ -620,7 +612,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
			__cpufreq_driver_target(

					this_dbs_info->cur_policy,

					policy->min, CPUFREQ_RELATION_L);

		mutex_unlock(&dbs_mutex);

		mutex_unlock(&this_dbs_info->timer_mutex);



		break;

	}