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authorHenry Willard <henry.willard@oracle.com>2018-08-15 03:01:02 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-08-17 00:03:29 +0300
commit2a3eb51e30b9ac66fe1b75877627a7e4aaeca24a (patch)
tree82ebe04aa0d83961db2354dd77e6d9c56a589849 /drivers/cpufreq
parentb018fc9800557bd14a40d69501e19c340eb2c521 (diff)
downloadlinux-2a3eb51e30b9ac66fe1b75877627a7e4aaeca24a.tar.xz
cpufreq: governor: Avoid accessing invalid governor_data
If cppc_cpufreq.ko is deleted at the same time that tuned-adm is changing profiles, there is a small chance that a race can occur between cpufreq_dbs_governor_exit() and cpufreq_dbs_governor_limits() resulting in a system failure when the latter tries to use policy->governor_data that has been freed by the former. This patch uses gov_dbs_data_mutex to synchronize access. Fixes: e788892ba3cc (cpufreq: governor: Get rid of governor events) Signed-off-by: Henry Willard <henry.willard@oracle.com> [ rjw: Subject, minor white space adjustment ] Cc: 4.8+ <stable@vger.kernel.org> # 4.8+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/cpufreq_governor.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 1d50e97d49f1..6d53f7d9fc7a 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -555,12 +555,20 @@ EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_stop);
void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy)
{
- struct policy_dbs_info *policy_dbs = policy->governor_data;
+ struct policy_dbs_info *policy_dbs;
+
+ /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit() */
+ mutex_lock(&gov_dbs_data_mutex);
+ policy_dbs = policy->governor_data;
+ if (!policy_dbs)
+ goto out;
mutex_lock(&policy_dbs->update_mutex);
cpufreq_policy_apply_limits(policy);
gov_update_sample_delay(policy_dbs, 0);
-
mutex_unlock(&policy_dbs->update_mutex);
+
+out:
+ mutex_unlock(&gov_dbs_data_mutex);
}
EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);