From 11e584cfb8a9d2226151fd39bfa74d09e575f72d Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 10 Jun 2015 02:11:45 +0200 Subject: [PATCH] cpufreq: Don't allow updating inactive policies from sysfs Later commits would change the way policies are managed today. Policies wouldn't be freed on cpu hotplug (currently they aren't freed only for suspend), and while the CPU is offline, the sysfs cpufreq files would still be present. User may accidentally try to update the sysfs files in following directory: '/sys/devices/system/cpu/cpuX/cpufreq/'. And that would result in undefined behavior as policy wouldn't be active then. Apart from updating the store() routine, we also update __cpufreq_get() which can call cpufreq_out_of_sync(). The later routine tries to update policy->cur and starts notifying kernel about it. Signed-off-by: Viresh Kumar Acked-by: Saravana Kannan Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 5d780ff..16214df 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -875,11 +875,18 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr, down_write(&policy->rwsem); + /* Updating inactive policies is invalid, so avoid doing that. */ + if (unlikely(policy_is_inactive(policy))) { + ret = -EBUSY; + goto unlock_policy_rwsem; + } + if (fattr->store) ret = fattr->store(policy, buf, count); else ret = -EIO; +unlock_policy_rwsem: up_write(&policy->rwsem); up_read(&cpufreq_rwsem); @@ -1610,6 +1617,10 @@ static unsigned int __cpufreq_get(struct cpufreq_policy *policy) ret_freq = cpufreq_driver->get(policy->cpu); + /* Updating inactive policies is invalid, so avoid doing that. */ + if (unlikely(policy_is_inactive(policy))) + return ret_freq; + if (ret_freq && policy->cur && !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) { /* verify no discrepancy between actual and -- 2.7.4