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cpufreq: Add cpufreq_cpu_acquire() and cpufreq_cpu_release() 

It sometimes is necessary to find a cpufreq policy for a given CPU
and acquire its rwsem (for writing) immediately after that, so
introduce cpufreq_cpu_acquire() as a helper for that and the
complementary cpufreq_cpu_release().

Make cpufreq_update_policy() use the new functions.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
This commit is contained in:
Rafael J. Wysocki 2019-03-26 12:16:58 +01:00
parent 5a25e3f7cc
commit 540a375822
1 changed files with 47 additions and 9 deletions
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56
drivers/cpufreq/cpufreq.c
View File

@ -250,6 +250,51 @@ void cpufreq_cpu_put(struct cpufreq_policy *policy)
}
EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
/**
* cpufreq_cpu_release - Unlock a policy and decrement its usage counter.
* @policy: cpufreq policy returned by cpufreq_cpu_acquire().
*/
static void cpufreq_cpu_release(struct cpufreq_policy *policy)
{
if (WARN_ON(!policy))
return;
lockdep_assert_held(&policy->rwsem);
up_write(&policy->rwsem);
cpufreq_cpu_put(policy);
}
/**
* cpufreq_cpu_acquire - Find policy for a CPU, mark it as busy and lock it.
* @cpu: CPU to find the policy for.
*
* Call cpufreq_cpu_get() to get a reference on the cpufreq policy for @cpu and
* if the policy returned by it is not NULL, acquire its rwsem for writing.
* Return the policy if it is active or release it and return NULL otherwise.
*
* The policy returned by this function has to be released with the help of
* cpufreq_cpu_release() in order to release its rwsem and balance its usage
* counter properly.
*/
static struct cpufreq_policy *cpufreq_cpu_acquire(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
if (!policy)
return NULL;
down_write(&policy->rwsem);
if (policy_is_inactive(policy)) {
cpufreq_cpu_release(policy);
return NULL;
}
return policy;
}
/*********************************************************************
* EXTERNALLY AFFECTING FREQUENCY CHANGES *
*********************************************************************/
@ -2337,17 +2382,12 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
*/
void cpufreq_update_policy(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
struct cpufreq_policy *policy = cpufreq_cpu_acquire(cpu);
struct cpufreq_policy new_policy;
if (!policy)
return;
down_write(&policy->rwsem);
if (policy_is_inactive(policy))
goto unlock;
/*
* BIOS might change freq behind our back
* -> ask driver for current freq and notify governors about a change
@ -2364,9 +2404,7 @@ void cpufreq_update_policy(unsigned int cpu)
cpufreq_set_policy(policy, &new_policy);
unlock:
up_write(&policy->rwsem);
cpufreq_cpu_put(policy);
cpufreq_cpu_release(policy);
}
EXPORT_SYMBOL(cpufreq_update_policy);