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.
Signed-off-by: Henry Willard <henry.will...@oracle.com>
---
drivers/cpufreq/cpufreq_governor.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/cpufreq_governor.c
b/drivers/cpufreq/cpufreq_governor.c
index 1d50e97d49f1..43416ee55849 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -555,12 +555,20 @@ void cpufreq_dbs_governor_stop(struct cpufreq_policy
*policy)
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);
--
1.8.3.1
