[RFC PATCH 02/19] cpufreq: merge governor lock and mutex

From: Juri Lelli
Date: Mon Jan 11 2016 - 12:37:24 EST


From: Michael Turquette <mturquette@xxxxxxxxxxxx>

Commit 95731ebb114c ("cpufreq: Fix governor start/stop race condition")
introduced cpufreq_governor_lock. This was actually overkilling, as the
same can be achieved by using the existing cpufreq_governor_mutex.
Removing cpufreq_governor_lock cleans things up and makes deadlocks less
likely to happen.

Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Signed-off-by: Michael Turquette <mturquette@xxxxxxxxxxxx>
---
drivers/cpufreq/cpufreq.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 7bdd845..0802705 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -102,7 +102,7 @@ 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);
-static DEFINE_MUTEX(cpufreq_governor_lock);
+static DEFINE_MUTEX(cpufreq_governor_mutex);

/* Flag to suspend/resume CPUFreq governors */
static bool cpufreq_suspended;
@@ -146,7 +146,6 @@ void disable_cpufreq(void)
{
off = 1;
}
-static DEFINE_MUTEX(cpufreq_governor_mutex);

bool have_governor_per_policy(void)
{
@@ -1963,11 +1962,11 @@ 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);
+ mutex_lock(&cpufreq_governor_mutex);
if ((policy->governor_enabled && event == CPUFREQ_GOV_START)
|| (!policy->governor_enabled
&& (event == CPUFREQ_GOV_LIMITS || event == CPUFREQ_GOV_STOP))) {
- mutex_unlock(&cpufreq_governor_lock);
+ mutex_unlock(&cpufreq_governor_mutex);
return -EBUSY;
}

@@ -1976,7 +1975,7 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
else if (event == CPUFREQ_GOV_START)
policy->governor_enabled = true;

- mutex_unlock(&cpufreq_governor_lock);
+ mutex_unlock(&cpufreq_governor_mutex);

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

@@ -1987,12 +1986,12 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
policy->governor->initialized--;
} else {
/* Restore original values */
- mutex_lock(&cpufreq_governor_lock);
+ mutex_lock(&cpufreq_governor_mutex);
if (event == CPUFREQ_GOV_STOP)
policy->governor_enabled = true;
else if (event == CPUFREQ_GOV_START)
policy->governor_enabled = false;
- mutex_unlock(&cpufreq_governor_lock);
+ mutex_unlock(&cpufreq_governor_mutex);
}

if (((event == CPUFREQ_GOV_POLICY_INIT) && ret) ||
--
2.2.2