diff mbox

[V2,7/7] cpufreq: Remove cpufreq_governor_lock

Message ID 20160204064304.GA3469@vireshk
State New
Headers show

Commit Message

Viresh Kumar Feb. 4, 2016, 6:43 a.m. UTC 
On 03-02-16, 19:32, Viresh Kumar wrote:
> We used to drop policy->rwsem just before calling __cpufreq_governor()

> in some cases earlier and so it was possible that __cpufreq_governor()

> runs concurrently via separate threads.

> 

> In order to guarantee valid state transitions for governors,

> 'governor_enabled' was required to be protected using some locking and

> we created cpufreq_governor_lock for that.

> 

> But now, __cpufreq_governor() is always called from within policy->rwsem

> held and so 'governor_enabled' is protected against races even without

> cpufreq_governor_lock.

> 

> Get rid of the extra lock now.

> 

> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

> ---

>  drivers/cpufreq/cpufreq.c | 7 -------

>  1 file changed, 7 deletions(-)

> 

> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c

> index 4fc3889ca7c9..7bc8a5ed97e5 100644

> --- a/drivers/cpufreq/cpufreq.c

> +++ b/drivers/cpufreq/cpufreq.c

> @@ -102,7 +102,6 @@ static LIST_HEAD(cpufreq_governor_list);

>  static struct cpufreq_driver *cpufreq_driver;

>  static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);

>  static DEFINE_RWLOCK(cpufreq_driver_lock);

> -DEFINE_MUTEX(cpufreq_governor_lock);

>  

>  /* Flag to suspend/resume CPUFreq governors */

>  static bool cpufreq_suspended;

> @@ -1963,11 +1962,9 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,

>  

>  	pr_debug("%s: for CPU %u, event %u\n", __func__, policy->cpu, event);

>  

> -	mutex_lock(&cpufreq_governor_lock);

>  	if ((policy->governor_enabled && event == CPUFREQ_GOV_START)

>  	    || (!policy->governor_enabled

>  	    && (event == CPUFREQ_GOV_LIMITS || event == CPUFREQ_GOV_STOP))) {

> -		mutex_unlock(&cpufreq_governor_lock);

>  		return -EBUSY;

>  	}

>  

> @@ -1976,8 +1973,6 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,

>  	else if (event == CPUFREQ_GOV_START)

>  		policy->governor_enabled = true;

>  

> -	mutex_unlock(&cpufreq_governor_lock);

> -

>  	ret = policy->governor->governor(policy, event);

>  

>  	if (!ret) {

> @@ -1987,12 +1982,10 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,

>  			policy->governor->initialized--;

>  	} else {

>  		/* Restore original values */

> -		mutex_lock(&cpufreq_governor_lock);

>  		if (event == CPUFREQ_GOV_STOP)

>  			policy->governor_enabled = true;

>  		else if (event == CPUFREQ_GOV_START)

>  			policy->governor_enabled = false;

> -		mutex_unlock(&cpufreq_governor_lock);

>  	}

>  

>  	if (((event == CPUFREQ_GOV_POLICY_INIT) && ret) ||


+ minor cleanup:


-- 
viresh
diff mbox

Patch

diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index ed328a39c4ac..7bed63e14e7d 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -214,7 +214,6 @@  static inline int delay_for_sampling_rate(unsigned int sampling_rate)
        return delay;
 }
 
-extern struct mutex cpufreq_governor_lock;
 extern const struct sysfs_ops governor_sysfs_ops;
 
 void gov_add_timers(struct cpufreq_policy *policy, unsigned int delay);