cpufreq: Abort show()/store() for half-initialized policies

If policy initialization fails after the sysfs files are created,
there is a possibility to end up running show()/store() callbacks
for half-initialized policies, which may have unpredictable
outcomes.

Abort show()/store() in such a case by making sure the policy is active.

Also dectivate the policy on such failures.

Signed-off-by: Schspa Shi <schspa@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1f6667ce43bdd304f9bfb0cc2720c43a7390d1c1..f75197b924ef2754101c810d939df9582ef40d7c 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -948,13 +948,14 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
 {
        struct cpufreq_policy *policy = to_policy(kobj);
        struct freq_attr *fattr = to_attr(attr);
-       ssize_t ret;
+       ssize_t ret = -EBUSY;
 
        if (!fattr->show)
                return -EIO;
 
        down_read(&policy->rwsem);
-       ret = fattr->show(policy, buf);
+       if (likely(!policy_is_inactive(policy)))
+               ret = fattr->show(policy, buf);
        up_read(&policy->rwsem);
 
        return ret;
@@ -965,7 +966,7 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
 {
        struct cpufreq_policy *policy = to_policy(kobj);
        struct freq_attr *fattr = to_attr(attr);
-       ssize_t ret = -EINVAL;
+       ssize_t ret = -EBUSY;
 
        if (!fattr->store)
                return -EIO;
@@ -979,7 +980,8 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
 
        if (cpu_online(policy->cpu)) {
                down_write(&policy->rwsem);
-               ret = fattr->store(policy, buf, count);
+               if (likely(!policy_is_inactive(policy)))
+                       ret = fattr->store(policy, buf, count);
                up_write(&policy->rwsem);
        }
 
@@ -1535,6 +1537,7 @@ out_destroy_policy:
        for_each_cpu(j, policy->real_cpus)
                remove_cpu_dev_symlink(policy, j, get_cpu_device(j));
 
+       cpumask_clear(policy->cpus);
        up_write(&policy->rwsem);
 
 out_offline_policy: