cpufreq: Initialize policy before making it available for others to use

Policy must be fully initialized before it is being made available
for use by others. Otherwise cpufreq_cpu_get() would be able to grab
a half initialized policy structure that might not have affected_cpus
(for example) populated. Then, anybody accessing those fields will get
a wrong value and that will lead to unpredictable results.

In order to fix this, do all the necessary initialization before we
make the policy structure available via cpufreq_cpu_get(). That will
guarantee that any code accessing fields of the policy will get
correct data from them.

Reported-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index c4cacab..d662268 100644 (file)
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1109,6 +1109,20 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
                goto err_set_policy_cpu;
        }
 
+       /* related cpus should atleast have policy->cpus */
+       cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);
+
+       /*
+        * affected cpus must always be the one, which are online. We aren't
+        * managing offline cpus here.
+        */
+       cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);
+
+       if (!frozen) {
+               policy->user_policy.min = policy->min;
+               policy->user_policy.max = policy->max;
+       }
+
        write_lock_irqsave(&cpufreq_driver_lock, flags);
        for_each_cpu(j, policy->cpus)
                per_cpu(cpufreq_cpu_data, j) = policy;
@@ -1162,20 +1176,6 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
                }
        }
 
-       /* related cpus should atleast have policy->cpus */
-       cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);
-
-       /*
-        * affected cpus must always be the one, which are online. We aren't
-        * managing offline cpus here.
-        */
-       cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);
-
-       if (!frozen) {
-               policy->user_policy.min = policy->min;
-               policy->user_policy.max = policy->max;
-       }
-
        blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
                                     CPUFREQ_START, policy);