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-rw-r--r--drivers/cpufreq/cpufreq.c135
1 files changed, 57 insertions, 78 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index f149e14f77c7..c9bbfeef92e3 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -91,6 +91,12 @@ static void unlock_policy_rwsem_##mode(int cpu) \
unlock_policy_rwsem(read, cpu);
unlock_policy_rwsem(write, cpu);
+/*
+ * rwsem to guarantee that cpufreq driver module doesn't unload during critical
+ * sections
+ */
+static DECLARE_RWSEM(cpufreq_rwsem);
+
/* internal prototypes */
static int __cpufreq_governor(struct cpufreq_policy *policy,
unsigned int event);
@@ -178,78 +184,46 @@ u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy)
}
EXPORT_SYMBOL_GPL(get_cpu_idle_time);
-static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
+struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
{
- struct cpufreq_policy *policy;
+ struct cpufreq_policy *policy = NULL;
unsigned long flags;
- if (cpu >= nr_cpu_ids)
- goto err_out;
+ if (cpufreq_disabled() || (cpu >= nr_cpu_ids))
+ return NULL;
+
+ if (!down_read_trylock(&cpufreq_rwsem))
+ return NULL;
/* get the cpufreq driver */
read_lock_irqsave(&cpufreq_driver_lock, flags);
- if (!cpufreq_driver)
- goto err_out_unlock;
-
- if (!try_module_get(cpufreq_driver->owner))
- goto err_out_unlock;
+ if (cpufreq_driver) {
+ /* get the CPU */
+ policy = per_cpu(cpufreq_cpu_data, cpu);
+ if (policy)
+ kobject_get(&policy->kobj);
+ }
- /* get the CPU */
- policy = per_cpu(cpufreq_cpu_data, cpu);
+ read_unlock_irqrestore(&cpufreq_driver_lock, flags);
if (!policy)
- goto err_out_put_module;
-
- if (!sysfs && !kobject_get(&policy->kobj))
- goto err_out_put_module;
+ up_read(&cpufreq_rwsem);
- read_unlock_irqrestore(&cpufreq_driver_lock, flags);
return policy;
-
-err_out_put_module:
- module_put(cpufreq_driver->owner);
-err_out_unlock:
- read_unlock_irqrestore(&cpufreq_driver_lock, flags);
-err_out:
- return NULL;
-}
-
-struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
-{
- if (cpufreq_disabled())
- return NULL;
-
- return __cpufreq_cpu_get(cpu, false);
}
EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
-static struct cpufreq_policy *cpufreq_cpu_get_sysfs(unsigned int cpu)
-{
- return __cpufreq_cpu_get(cpu, true);
-}
-
-static void __cpufreq_cpu_put(struct cpufreq_policy *policy, bool sysfs)
-{
- if (!sysfs)
- kobject_put(&policy->kobj);
- module_put(cpufreq_driver->owner);
-}
-
void cpufreq_cpu_put(struct cpufreq_policy *policy)
{
if (cpufreq_disabled())
return;
- __cpufreq_cpu_put(policy, false);
+ kobject_put(&policy->kobj);
+ up_read(&cpufreq_rwsem);
}
EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
-static void cpufreq_cpu_put_sysfs(struct cpufreq_policy *policy)
-{
- __cpufreq_cpu_put(policy, true);
-}
-
/*********************************************************************
* EXTERNALLY AFFECTING FREQUENCY CHANGES *
*********************************************************************/
@@ -694,12 +668,12 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
struct cpufreq_policy *policy = to_policy(kobj);
struct freq_attr *fattr = to_attr(attr);
ssize_t ret = -EINVAL;
- policy = cpufreq_cpu_get_sysfs(policy->cpu);
- if (!policy)
- goto no_policy;
+
+ if (!down_read_trylock(&cpufreq_rwsem))
+ goto exit;
if (lock_policy_rwsem_read(policy->cpu) < 0)
- goto fail;
+ goto up_read;
if (fattr->show)
ret = fattr->show(policy, buf);
@@ -707,9 +681,10 @@ static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
ret = -EIO;
unlock_policy_rwsem_read(policy->cpu);
-fail:
- cpufreq_cpu_put_sysfs(policy);
-no_policy:
+
+up_read:
+ up_read(&cpufreq_rwsem);
+exit:
return ret;
}
@@ -719,12 +694,12 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
struct cpufreq_policy *policy = to_policy(kobj);
struct freq_attr *fattr = to_attr(attr);
ssize_t ret = -EINVAL;
- policy = cpufreq_cpu_get_sysfs(policy->cpu);
- if (!policy)
- goto no_policy;
+
+ if (!down_read_trylock(&cpufreq_rwsem))
+ goto exit;
if (lock_policy_rwsem_write(policy->cpu) < 0)
- goto fail;
+ goto up_read;
if (fattr->store)
ret = fattr->store(policy, buf, count);
@@ -732,9 +707,10 @@ static ssize_t store(struct kobject *kobj, struct attribute *attr,
ret = -EIO;
unlock_policy_rwsem_write(policy->cpu);
-fail:
- cpufreq_cpu_put_sysfs(policy);
-no_policy:
+
+up_read:
+ up_read(&cpufreq_rwsem);
+exit:
return ret;
}
@@ -1003,25 +979,24 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
return 0;
}
+ if (!down_read_trylock(&cpufreq_rwsem))
+ return 0;
+
#ifdef CONFIG_HOTPLUG_CPU
/* Check if this cpu was hot-unplugged earlier and has siblings */
read_lock_irqsave(&cpufreq_driver_lock, flags);
list_for_each_entry(tpolicy, &cpufreq_policy_list, policy_list) {
if (cpumask_test_cpu(cpu, tpolicy->related_cpus)) {
read_unlock_irqrestore(&cpufreq_driver_lock, flags);
- return cpufreq_add_policy_cpu(tpolicy, cpu, dev,
- frozen);
+ ret = cpufreq_add_policy_cpu(tpolicy, cpu, dev, frozen);
+ up_read(&cpufreq_rwsem);
+ return ret;
}
}
read_unlock_irqrestore(&cpufreq_driver_lock, flags);
#endif
#endif
- if (!try_module_get(cpufreq_driver->owner)) {
- ret = -EINVAL;
- goto module_out;
- }
-
if (frozen)
/* Restore the saved policy when doing light-weight init */
policy = cpufreq_policy_restore(cpu);
@@ -1094,7 +1069,8 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
cpufreq_init_policy(policy);
kobject_uevent(&policy->kobj, KOBJ_ADD);
- module_put(cpufreq_driver->owner);
+ up_read(&cpufreq_rwsem);
+
pr_debug("initialization complete\n");
return 0;
@@ -1112,8 +1088,8 @@ err_set_policy_cpu:
per_cpu(cpufreq_policy_cpu, cpu) = -1;
cpufreq_policy_free(policy);
nomem_out:
- module_put(cpufreq_driver->owner);
-module_out:
+ up_read(&cpufreq_rwsem);
+
return ret;
}
@@ -1425,10 +1401,9 @@ static unsigned int __cpufreq_get(unsigned int cpu)
unsigned int cpufreq_get(unsigned int cpu)
{
unsigned int ret_freq = 0;
- struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
- if (!policy)
- goto out;
+ if (!down_read_trylock(&cpufreq_rwsem))
+ return 0;
if (unlikely(lock_policy_rwsem_read(cpu)))
goto out_policy;
@@ -1438,8 +1413,8 @@ unsigned int cpufreq_get(unsigned int cpu)
unlock_policy_rwsem_read(cpu);
out_policy:
- cpufreq_cpu_put(policy);
-out:
+ up_read(&cpufreq_rwsem);
+
return ret_freq;
}
EXPORT_SYMBOL(cpufreq_get);
@@ -2132,9 +2107,13 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
subsys_interface_unregister(&cpufreq_interface);
unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
+ down_write(&cpufreq_rwsem);
write_lock_irqsave(&cpufreq_driver_lock, flags);
+
cpufreq_driver = NULL;
+
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ up_write(&cpufreq_rwsem);
return 0;
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-29 19:26:38 +0000