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authorViresh Kumar <viresh.kumar@linaro.org>2015-06-10 03:11:45 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-06-10 03:11:45 +0300
commit11e584cfb8a9d2226151fd39bfa74d09e575f72d (patch)
treef33f50ab77df6f5d161820c64415481e5ba0189a /drivers
parent6c1e45917dec5e7c99ba8125fd8cc50f6e482a21 (diff)
downloadlinux-11e584cfb8a9d2226151fd39bfa74d09e575f72d.tar.xz
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 <viresh.kumar@linaro.org> Acked-by: Saravana Kannan <skannan@codeaurora.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/cpufreq/cpufreq.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 5d780ff5a10a..16214dfe78c5 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