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cpufreq: sched: Helpers to add and remove update_util hooks

Browse source 
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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Rafael J. Wysocki 2016-04-02 01:08:43 +02:00
parent 9fa64d6424
commit 0bed612be6
4 changed files with 82 additions and 54 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

76
drivers/cpufreq/cpufreq_governor.c
View file

@ -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;
}

7
drivers/cpufreq/intel_pstate.c
View file

@ -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();
}

5
include/linux/sched.h
View file

@ -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

48
kernel/sched/cpufreq.c
View file

@ -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.
*
* 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_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 || !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_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_set_update_util_data(int cpu, struct update_util_data *data)
void cpufreq_remove_update_util_hook(int cpu)
{
if (WARN_ON(data && !data->func))
return;
rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
}
EXPORT_SYMBOL_GPL(cpufreq_set_update_util_data);
EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);