3 files changed, 11 insertions, 5 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index d270e8eb3e67..6e2ec0b18948 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -808,7 +808,7 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
                 ret = -ENOMEM;
                 goto nomem_out;
         }
-        if (!alloc_cpumask_var(&policy->related_cpus, GFP_KERNEL)) {
+        if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL)) {
                 free_cpumask_var(policy->cpus);
                 kfree(policy);
                 ret = -ENOMEM;
@@ -1070,11 +1070,11 @@ static int __cpufreq_remove_dev(struct sys_device *sys_dev)
         spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
 #endif
 
+        unlock_policy_rwsem_write(cpu);
+
         if (cpufreq_driver->target)
                 __cpufreq_governor(data, CPUFREQ_GOV_STOP);
 
-        unlock_policy_rwsem_write(cpu);
-
         kobject_put(&data->kobj);
 
         /* we need to make sure that the underlying kobj is actually
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 2ecd95e4ab1a..7a74d175287b 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -91,6 +91,9 @@ static unsigned int dbs_enable;	/* number of CPUs using this policy */
  * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
  * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
  * is recursive for the same process. -Venki
+ * DEADLOCK ALERT! (2) : do_dbs_timer() must not take the dbs_mutex, because it
+ * would deadlock with cancel_delayed_work_sync(), which is needed for proper
+ * raceless workqueue teardown.
  */
 static DEFINE_MUTEX(dbs_mutex);
 
@@ -542,7 +545,7 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 {
         dbs_info->enable = 0;
-        cancel_delayed_work(&dbs_info->work);
+        cancel_delayed_work_sync(&dbs_info->work);
 }
 
 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 338f428a15b7..e741c339df76 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -98,6 +98,9 @@ static unsigned int dbs_enable;	/* number of CPUs using this policy */
  * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
  * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
  * is recursive for the same process. -Venki
+ * DEADLOCK ALERT! (2) : do_dbs_timer() must not take the dbs_mutex, because it
+ * would deadlock with cancel_delayed_work_sync(), which is needed for proper
+ * raceless workqueue teardown.
  */
 static DEFINE_MUTEX(dbs_mutex);
 
@@ -562,7 +565,7 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 {
         dbs_info->enable = 0;
-        cancel_delayed_work(&dbs_info->work);
+        cancel_delayed_work_sync(&dbs_info->work);
 }
 
 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,