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authorViresh Kumar <viresh.kumar@linaro.org>2013-08-06 22:53:10 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-08-10 03:24:47 +0200
commitfe492f3f0332e23cc6ca4913e5a2ed78e1888902 (patch)
tree0e87539040aabaf02babc0edc49fbb27610b0e3b /drivers/cpufreq/cpufreq.c
parenteb608521f1e25a8c14295b6d9a3853c3cd8c6cf8 (diff)
cpufreq: Fix broken usage of governor->owner's refcount
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>
Diffstat (limited to 'drivers/cpufreq/cpufreq.c')
-rw-r--r--drivers/cpufreq/cpufreq.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 37af929746a..f149e14f77c 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -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;