iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

cpufreq: Fix broken usage of governor->owner's refcount

Browse Source 
The cpufreq governor owner refcount usage is broken.  We should only
increment that refcount when a CPUFREQ_GOV_POLICY_INIT event has come
and it should only be decremented if CPUFREQ_GOV_POLICY_EXIT has come.

Currently, there can be situations where the governor is in use, but
we have allowed it to be unloaded which may result in undefined
behavior.  Let's fix it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Viresh Kumar 2013-08-06 22:53:10 +05:30 committed by Rafael J. Wysocki
parent eb608521f1
commit fe492f3f03
1 changed files with 7 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/cpufreq/cpufreq.c
View File

@ -1709,8 +1709,9 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
}
}
if (!try_module_get(policy->governor->owner))
return -EINVAL;
if (event == CPUFREQ_GOV_POLICY_INIT)
if (!try_module_get(policy->governor->owner))
return -EINVAL;
pr_debug("__cpufreq_governor for CPU %u, event %u\n",
policy->cpu, event);
@ -1719,6 +1720,8 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
if ((!policy->governor_enabled && (event == CPUFREQ_GOV_STOP)) ||
(policy->governor_enabled && (event == CPUFREQ_GOV_START))) {
mutex_unlock(&cpufreq_governor_lock);
if (event == CPUFREQ_GOV_POLICY_INIT)
module_put(policy->governor->owner);
return -EBUSY;
}
@ -1746,11 +1749,8 @@ static int __cpufreq_governor(struct cpufreq_policy *policy,
mutex_unlock(&cpufreq_governor_lock);
}
/* we keep one module reference alive for
each CPU governed by this CPU */
if ((event != CPUFREQ_GOV_START) || ret)
module_put(policy->governor->owner);
if ((event == CPUFREQ_GOV_STOP) && !ret)
if (((event == CPUFREQ_GOV_POLICY_INIT) && ret) ||
((event == CPUFREQ_GOV_POLICY_EXIT) && !ret))
module_put(policy->governor->owner);
return ret;