1 files changed, 31 insertions, 79 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 87ed83a..6c9cbb9 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -53,47 +53,6 @@ static inline bool has_target(void)
 }
 
 /*
- * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
- * all cpufreq/hotplug/workqueue/etc related lock issues.
- *
- * The rules for this semaphore:
- * - Any routine that wants to read from the policy structure will
- *   do a down_read on this semaphore.
- * - Any routine that will write to the policy structure and/or may take away
- *   the policy altogether (eg. CPU hotplug), will hold this lock in write
- *   mode before doing so.
- *
- * Additional rules:
- * - Governor routines that can be called in cpufreq hotplug path should not
- *   take this sem as top level hotplug notifier handler takes this.
- * - Lock should not be held across
- *     __cpufreq_governor(data, CPUFREQ_GOV_STOP);
- */
-static DEFINE_PER_CPU(struct rw_semaphore, cpu_policy_rwsem);
-
-#define lock_policy_rwsem(mode, cpu)					\
-static void lock_policy_rwsem_##mode(int cpu)				\
-{									\
-	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);	\
-	BUG_ON(!policy);						\
-	down_##mode(&per_cpu(cpu_policy_rwsem, policy->cpu));		\
-}
-
-lock_policy_rwsem(read, cpu);
-lock_policy_rwsem(write, cpu);
-
-#define unlock_policy_rwsem(mode, cpu)					\
-static void unlock_policy_rwsem_##mode(int cpu)				\
-{									\
-	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);	\
-	BUG_ON(!policy);						\
-	up_##mode(&per_cpu(cpu_policy_rwsem, policy->cpu));		\
-}
-
-unlock_policy_rwsem(read, cpu);
-unlock_policy_rwsem(write, cpu);
-
-/*
  * rwsem to guarantee that cpufreq driver module doesn't unload during critical
  * sections
  */
@@ -688,14 +647,14 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
 	if (!down_read_trylock(&cpufreq_rwsem))
 		return -EINVAL;
 
-	lock_policy_rwsem_read(policy->cpu);
+	down_read(&policy->rwsem);
 
 	if (fattr->show)
 		ret = fattr->show(policy, buf);
 	else
 		ret = -EIO;
 
-	unlock_policy_rwsem_read(policy->cpu);
+	up_read(&policy->rwsem);
 	up_read(&cpufreq_rwsem);
 
 	return ret;
@@ -716,14 +675,14 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
 	if (!down_read_trylock(&cpufreq_rwsem))
 		goto unlock;
 
-	lock_policy_rwsem_write(policy->cpu);
+	down_write(&policy->rwsem);
 
 	if (fattr->store)
 		ret = fattr->store(policy, buf, count);
 	else
 		ret = -EIO;
 
-	unlock_policy_rwsem_write(policy->cpu);
+	up_write(&policy->rwsem);
 
 	up_read(&cpufreq_rwsem);
 unlock:
@@ -900,7 +859,7 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy,
 		}
 	}
 
-	lock_policy_rwsem_write(policy->cpu);
+	down_write(&policy->rwsem);
 
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 
@@ -908,7 +867,7 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy,
 	per_cpu(cpufreq_cpu_data, cpu) = policy;
 	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
-	unlock_policy_rwsem_write(policy->cpu);
+	up_write(&policy->rwsem);
 
 	if (has_target()) {
 		if ((ret = __cpufreq_governor(policy, CPUFREQ_GOV_START)) ||
@@ -955,6 +914,8 @@ static struct cpufreq_policy *cpufreq_policy_alloc(void)
 		goto err_free_cpumask;
 
 	INIT_LIST_HEAD(&policy->policy_list);
+	init_rwsem(&policy->rwsem);
+
 	return policy;
 
 err_free_cpumask:
@@ -977,19 +938,12 @@ static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
 	if (WARN_ON(cpu == policy->cpu))
 		return;
 
-	/*
-	 * Take direct locks as lock_policy_rwsem_write wouldn't work here.
-	 * Also lock for last cpu is enough here as contention will happen only
-	 * after policy->cpu is changed and after it is changed, other threads
-	 * will try to acquire lock for new cpu. And policy is already updated
-	 * by then.
-	 */
-	down_write(&per_cpu(cpu_policy_rwsem, policy->cpu));
+	down_write(&policy->rwsem);
 
 	policy->last_cpu = policy->cpu;
 	policy->cpu = cpu;
 
-	up_write(&per_cpu(cpu_policy_rwsem, policy->last_cpu));
+	up_write(&policy->rwsem);
 
 	cpufreq_frequency_table_update_policy_cpu(policy);
 	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
@@ -1181,9 +1135,9 @@ static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *policy,
 	if (ret) {
 		pr_err("%s: Failed to move kobj: %d", __func__, ret);
 
-		lock_policy_rwsem_write(old_cpu);
+		down_write(&policy->rwsem);
 		cpumask_set_cpu(old_cpu, policy->cpus);
-		unlock_policy_rwsem_write(old_cpu);
+		up_write(&policy->rwsem);
 
 		ret = sysfs_create_link(&cpu_dev->kobj, &policy->kobj,
 					"cpufreq");
@@ -1234,9 +1188,9 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
 			policy->governor->name, CPUFREQ_NAME_LEN);
 #endif
 
-	lock_policy_rwsem_read(cpu);
+	down_read(&policy->rwsem);
 	cpus = cpumask_weight(policy->cpus);
-	unlock_policy_rwsem_read(cpu);
+	up_read(&policy->rwsem);
 
 	if (cpu != policy->cpu) {
 		if (!frozen)
@@ -1276,12 +1230,12 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
 		return -EINVAL;
 	}
 
-	lock_policy_rwsem_write(cpu);
+	down_write(&policy->rwsem);
 	cpus = cpumask_weight(policy->cpus);
 
 	if (cpus > 1)
 		cpumask_clear_cpu(cpu, policy->cpus);
-	unlock_policy_rwsem_write(cpu);
+	up_write(&policy->rwsem);
 
 	/* If cpu is last user of policy, free policy */
 	if (cpus == 1) {
@@ -1296,10 +1250,10 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
 		}
 
 		if (!frozen) {
-			lock_policy_rwsem_read(cpu);
+			down_read(&policy->rwsem);
 			kobj = &policy->kobj;
 			cmp = &policy->kobj_unregister;
-			unlock_policy_rwsem_read(cpu);
+			up_read(&policy->rwsem);
 			kobject_put(kobj);
 
 			/*
@@ -1479,19 +1433,22 @@ static unsigned int __cpufreq_get(unsigned int cpu)
  */
 unsigned int cpufreq_get(unsigned int cpu)
 {
+	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
 	unsigned int ret_freq = 0;
 
 	if (cpufreq_disabled() || !cpufreq_driver)
 		return -ENOENT;
 
+	BUG_ON(!policy);
+
 	if (!down_read_trylock(&cpufreq_rwsem))
 		return 0;
 
-	lock_policy_rwsem_read(cpu);
+	down_read(&policy->rwsem);
 
 	ret_freq = __cpufreq_get(cpu);
 
-	unlock_policy_rwsem_read(cpu);
+	up_read(&policy->rwsem);
 	up_read(&cpufreq_rwsem);
 
 	return ret_freq;
@@ -1744,11 +1701,11 @@ int cpufreq_driver_target(struct cpufreq_policy *policy,
 {
 	int ret = -EINVAL;
 
-	lock_policy_rwsem_write(policy->cpu);
+	down_write(&policy->rwsem);
 
 	ret = __cpufreq_driver_target(policy, target_freq, relation);
 
-	unlock_policy_rwsem_write(policy->cpu);
+	up_write(&policy->rwsem);
 
 	return ret;
 }
@@ -1979,10 +1936,10 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
 			/* end old governor */
 			if (policy->governor) {
 				__cpufreq_governor(policy, CPUFREQ_GOV_STOP);
-				unlock_policy_rwsem_write(new_policy->cpu);
+				up_write(&policy->rwsem);
 				__cpufreq_governor(policy,
 						CPUFREQ_GOV_POLICY_EXIT);
-				lock_policy_rwsem_write(new_policy->cpu);
+				down_write(&policy->rwsem);
 			}
 
 			/* start new governor */
@@ -1991,10 +1948,10 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
 				if (!__cpufreq_governor(policy, CPUFREQ_GOV_START)) {
 					failed = 0;
 				} else {
-					unlock_policy_rwsem_write(new_policy->cpu);
+					up_write(&policy->rwsem);
 					__cpufreq_governor(policy,
 							CPUFREQ_GOV_POLICY_EXIT);
-					lock_policy_rwsem_write(new_policy->cpu);
+					down_write(&policy->rwsem);
 				}
 			}
 
@@ -2040,7 +1997,7 @@ int cpufreq_update_policy(unsigned int cpu)
 		goto no_policy;
 	}
 
-	lock_policy_rwsem_write(cpu);
+	down_write(&policy->rwsem);
 
 	pr_debug("updating policy for CPU %u\n", cpu);
 	memcpy(&new_policy, policy, sizeof(*policy));
@@ -2067,7 +2024,7 @@ int cpufreq_update_policy(unsigned int cpu)
 
 	ret = cpufreq_set_policy(policy, &new_policy);
 
-	unlock_policy_rwsem_write(cpu);
+	up_write(&policy->rwsem);
 
 	cpufreq_cpu_put(policy);
 no_policy:
@@ -2225,14 +2182,9 @@ EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
 
 static int __init cpufreq_core_init(void)
 {
-	int cpu;
-
 	if (cpufreq_disabled())
 		return -ENODEV;
 
-	for_each_possible_cpu(cpu)
-		init_rwsem(&per_cpu(cpu_policy_rwsem, cpu));
-
 	cpufreq_global_kobject = kobject_create();
 	BUG_ON(!cpufreq_global_kobject);
 	register_syscore_ops(&cpufreq_syscore_ops);