cpufreq: Remove cpufreq_governor_lock

We used to drop policy->rwsem just before calling __cpufreq_governor()
in some cases earlier and so it was possible that __cpufreq_governor()
ran concurrently via separate threads for the same policy.

In order to guarantee valid state transitions for governors,
'governor_enabled' was required to be protected using some locking
and cpufreq_governor_lock was added for that.

But now __cpufreq_governor() is always called under policy->rwsem,
and '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>
Tested-by: Juri Lelli <juri.lelli@arm.com>
Tested-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
[ rjw : Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 0 insertions, 8 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 692876892457..bc93272b4a12 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -147,8 +147,6 @@ void cpufreq_update_util(u64 time, unsigned long util, unsigned long max)
         rcu_read_unlock();
 }
 
-DEFINE_MUTEX(cpufreq_governor_lock);
-
 /* Flag to suspend/resume CPUFreq governors */
 static bool cpufreq_suspended;
 
@@ -2015,11 +2013,9 @@ 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;
         }
 
@@ -2028,8 +2024,6 @@ 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) {
@@ -2039,12 +2033,10 @@ 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) ||