Commit 0bed612b authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

cpufreq: sched: Helpers to add and remove update_util hooks 



Replace the single helper for adding and removing cpufreq utilization
update hooks, cpufreq_set_update_util_data(), with a pair of helpers,
cpufreq_add_update_util_hook() and cpufreq_remove_update_util_hook(),
and modify the users of cpufreq_set_update_util_data() accordingly.

With the new helpers, the code using them doesn't need to worry
about the internals of struct update_util_data and in particular
it doesn't need to worry about populating the func field in it
properly upfront.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent 9fa64d64

drivers/cpufreq/cpufreq_governor.c

+38 −38
Original line number Diff line number Diff line
@@ -258,43 +258,6 @@ unsigned int dbs_update(struct cpufreq_policy *policy) 
}

EXPORT_SYMBOL_GPL(dbs_update);



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_set_update_util_data(cpu, &cdbs->update_util);

	}

}



static inline void gov_clear_update_util(struct cpufreq_policy *policy)

{

	int i;



	for_each_cpu(i, policy->cpus)

		cpufreq_set_update_util_data(i, NULL);



	synchronize_sched();

}



static void gov_cancel_work(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;

}



static void dbs_work_handler(struct work_struct *work)

{

	struct policy_dbs_info *policy_dbs;
@@ -382,6 +345,44 @@ static void dbs_update_util_handler(struct update_util_data *data, u64 time, 
	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_sched();

}



static void gov_cancel_work(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;

}



static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *policy,

						     struct dbs_governor *gov)

{
@@ -404,7 +405,6 @@ static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *poli 
		struct cpu_dbs_info *j_cdbs = &per_cpu(cpu_dbs, j);



		j_cdbs->policy_dbs = policy_dbs;

		j_cdbs->update_util.func = dbs_update_util_handler;

	}

	return policy_dbs;

}

drivers/cpufreq/intel_pstate.c

+3 −4
Original line number Diff line number Diff line
@@ -1107,8 +1107,6 @@ static int intel_pstate_init_cpu(unsigned int cpunum) 


	intel_pstate_busy_pid_reset(cpu);



	cpu->update_util.func = intel_pstate_update_util;



	pr_debug("intel_pstate: controlling: cpu %d\n", cpunum);



	return 0;
@@ -1132,12 +1130,13 @@ static void intel_pstate_set_update_util_hook(unsigned int cpu_num) 


	/* Prevent intel_pstate_update_util() from using stale data. */

	cpu->sample.time = 0;

	cpufreq_set_update_util_data(cpu_num, &cpu->update_util);

	cpufreq_add_update_util_hook(cpu_num, &cpu->update_util,

				     intel_pstate_update_util);

}



static void intel_pstate_clear_update_util_hook(unsigned int cpu)

{

	cpufreq_set_update_util_data(cpu, NULL);

	cpufreq_remove_update_util_hook(cpu);

	synchronize_sched();

}

include/linux/sched.h

+4 −1
Original line number Diff line number Diff line
@@ -3240,7 +3240,10 @@ struct update_util_data { 
		     u64 time, unsigned long util, unsigned long max);

};



void cpufreq_set_update_util_data(int cpu, struct update_util_data *data);

void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,

			void (*func)(struct update_util_data *data, u64 time,

				     unsigned long util, unsigned long max));

void cpufreq_remove_update_util_hook(int cpu);

#endif /* CONFIG_CPU_FREQ */



#endif

kernel/sched/cpufreq.c

+37 −11
Original line number Diff line number Diff line
@@ -14,24 +14,50 @@ 
DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);



/**

 * cpufreq_set_update_util_data - Populate the CPU's update_util_data pointer.

 * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.

 * @cpu: The CPU to set the pointer for.

 * @data: New pointer value.

 * @func: Callback function to set for the CPU.

 *

 * Set and publish the update_util_data pointer for the given CPU.  That pointer

 * points to a struct update_util_data object containing a callback function

 * to call from cpufreq_update_util().  That function will be called from an RCU

 * read-side critical section, so it must not sleep.

 * Set and publish the update_util_data pointer for the given CPU.

 *

 * Callers must use RCU-sched callbacks to free any memory that might be

 * accessed via the old update_util_data pointer or invoke synchronize_sched()

 * right after this function to avoid use-after-free.

 * The update_util_data pointer of @cpu is set to @data and the callback

 * function pointer in the target struct update_util_data is set to @func.

 * That function will be called by cpufreq_update_util() from RCU-sched

 * read-side critical sections, so it must not sleep.  @data will always be

 * passed to it as the first argument which allows the function to get to the

 * target update_util_data structure and its container.

 *

 * The update_util_data pointer of @cpu must be NULL when this function is

 * called or it will WARN() and return with no effect.

 */

void cpufreq_set_update_util_data(int cpu, struct update_util_data *data)

void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,

			void (*func)(struct update_util_data *data, u64 time,

				     unsigned long util, unsigned long max))

{

	if (WARN_ON(data && !data->func))

	if (WARN_ON(!data || !func))

		return;



	if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))

		return;



	data->func = func;

	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);

}

EXPORT_SYMBOL_GPL(cpufreq_set_update_util_data);
 
EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);



/**

 * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.

 * @cpu: The CPU to clear the pointer for.

 *

 * Clear the update_util_data pointer for the given CPU.

 *

 * Callers must use RCU-sched callbacks to free any memory that might be

 * accessed via the old update_util_data pointer or invoke synchronize_sched()

 * right after this function to avoid use-after-free.

 */

void cpufreq_remove_update_util_hook(int cpu)

{

	rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);

}

EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);

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