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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-02-21 00:53:06 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-03-09 14:41:10 +0100
commit1112e9d83e5cd153b35dfbb52721f8b3d3163016 (patch)
treee338d4ce1f73bd198d05492f57046d1e0903773f
parentcpufreq: governor: Make dbs_data_mutex static (diff)
downloadlinux-1112e9d83e5cd153b35dfbb52721f8b3d3163016.tar.xz
linux-1112e9d83e5cd153b35dfbb52721f8b3d3163016.zip
cpufreq: governor: Narrow down the dbs_data_mutex coverage
Since cpufreq_governor_dbs() is now always called with policy->rwsem held, it cannot be executed twice in parallel for the same policy. Thus it is not necessary to hold dbs_data_mutex around the invocations of cpufreq_governor_start/stop/limits() from it as those functions never modify any data that can be shared between different policies. However, cpufreq_governor_dbs() may be executed twice in parallal for different policies using the same gov->gdbs_data object and dbs_data_mutex is still necessary to protect that object against concurrent updates. For this reason, narrow down the dbs_data_mutex locking to cpufreq_governor_init/exit() where it is needed and rename the mutex to gov_dbs_data_mutex to reflect its purpose. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
-rw-r--r--drivers/cpufreq/cpufreq_governor.c46
1 files changed, 23 insertions, 23 deletions
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 4f0bd482b59e..542c9caf8815 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -24,7 +24,7 @@
static DEFINE_PER_CPU(struct cpu_dbs_info, cpu_dbs);
-static DEFINE_MUTEX(dbs_data_mutex);
+static DEFINE_MUTEX(gov_dbs_data_mutex);
/* Common sysfs tunables */
/**
@@ -421,10 +421,10 @@ static void free_policy_dbs_info(struct policy_dbs_info *policy_dbs,
static int cpufreq_governor_init(struct cpufreq_policy *policy)
{
struct dbs_governor *gov = dbs_governor_of(policy);
- struct dbs_data *dbs_data = gov->gdbs_data;
+ struct dbs_data *dbs_data;
struct policy_dbs_info *policy_dbs;
unsigned int latency;
- int ret;
+ int ret = 0;
/* State should be equivalent to EXIT */
if (policy->governor_data)
@@ -434,6 +434,10 @@ static int cpufreq_governor_init(struct cpufreq_policy *policy)
if (!policy_dbs)
return -ENOMEM;
+ /* Protect gov->gdbs_data against concurrent updates. */
+ mutex_lock(&gov_dbs_data_mutex);
+
+ dbs_data = gov->gdbs_data;
if (dbs_data) {
if (WARN_ON(have_governor_per_policy())) {
ret = -EINVAL;
@@ -446,8 +450,7 @@ static int cpufreq_governor_init(struct cpufreq_policy *policy)
dbs_data->usage_count++;
list_add(&policy_dbs->list, &dbs_data->policy_dbs_list);
mutex_unlock(&dbs_data->mutex);
-
- return 0;
+ goto out;
}
dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
@@ -488,7 +491,7 @@ static int cpufreq_governor_init(struct cpufreq_policy *policy)
get_governor_parent_kobj(policy),
"%s", gov->gov.name);
if (!ret)
- return 0;
+ goto out;
/* Failure, so roll back. */
pr_err("cpufreq: Governor initialization failed (dbs_data kobject init error %d)\n", ret);
@@ -502,6 +505,9 @@ static int cpufreq_governor_init(struct cpufreq_policy *policy)
free_policy_dbs_info:
free_policy_dbs_info(policy_dbs, gov);
+
+out:
+ mutex_unlock(&gov_dbs_data_mutex);
return ret;
}
@@ -512,6 +518,9 @@ static int cpufreq_governor_exit(struct cpufreq_policy *policy)
struct dbs_data *dbs_data = policy_dbs->dbs_data;
int count;
+ /* Protect gov->gdbs_data against concurrent updates. */
+ mutex_lock(&gov_dbs_data_mutex);
+
mutex_lock(&dbs_data->mutex);
list_del(&policy_dbs->list);
count = --dbs_data->usage_count;
@@ -533,6 +542,8 @@ static int cpufreq_governor_exit(struct cpufreq_policy *policy)
}
free_policy_dbs_info(policy_dbs, gov);
+
+ mutex_unlock(&gov_dbs_data_mutex);
return 0;
}
@@ -599,31 +610,20 @@ static int cpufreq_governor_limits(struct cpufreq_policy *policy)
int cpufreq_governor_dbs(struct cpufreq_policy *policy, unsigned int event)
{
- int ret = -EINVAL;
-
- /* Lock governor to block concurrent initialization of governor */
- mutex_lock(&dbs_data_mutex);
-
if (event == CPUFREQ_GOV_POLICY_INIT) {
- ret = cpufreq_governor_init(policy);
+ return cpufreq_governor_init(policy);
} else if (policy->governor_data) {
switch (event) {
case CPUFREQ_GOV_POLICY_EXIT:
- ret = cpufreq_governor_exit(policy);
- break;
+ return cpufreq_governor_exit(policy);
case CPUFREQ_GOV_START:
- ret = cpufreq_governor_start(policy);
- break;
+ return cpufreq_governor_start(policy);
case CPUFREQ_GOV_STOP:
- ret = cpufreq_governor_stop(policy);
- break;
+ return cpufreq_governor_stop(policy);
case CPUFREQ_GOV_LIMITS:
- ret = cpufreq_governor_limits(policy);
- break;
+ return cpufreq_governor_limits(policy);
}
}
-
- mutex_unlock(&dbs_data_mutex);
- return ret;
+ return -EINVAL;
}
EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);