In general rwlocks are discourged so we are moving it to use the rcu instead.
CC: "Rafael J. Wysocki" <rjw@xxxxxxx>
Signed-off-by: Nathan Zimmer <nzimmer@xxxxxxx>
---
drivers/cpufreq/cpufreq.c | 177 +++++++++++++++++++++++++---------------------
1 file changed, 98 insertions(+), 79 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 13a83a2..5c5b9f4 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -39,13 +39,13 @@
* level driver of CPUFreq support, and its spinlock. This lock
* also protects the cpufreq_cpu_data array.
*/
-static struct cpufreq_driver *cpufreq_driver;
+static struct cpufreq_driver __rcu *cpufreq_driver;
static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
#ifdef CONFIG_HOTPLUG_CPU
/* This one keeps track of the previously set governor of a removed CPU */
static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
#endif
-static DEFINE_RWLOCK(cpufreq_driver_lock);
+static DEFINE_SPINLOCK(cpufreq_driver_lock);
/*
* cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
@@ -143,21 +143,20 @@ static DEFINE_MUTEX(cpufreq_governor_mutex);
static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
{
struct cpufreq_policy *data;
- unsigned long flags;
+ struct cpufreq_driver *driver;
if (cpu >= nr_cpu_ids)
goto err_out;
/* get the cpufreq driver */
- read_lock_irqsave(&cpufreq_driver_lock, flags);
-
- if (!cpufreq_driver)
+ rcu_read_lock();
+ driver = rcu_dereference(cpufreq_driver);
+ if (!driver)
goto err_out_unlock;
- if (!try_module_get(cpufreq_driver->owner))
+ if (!try_module_get(driver->owner))
goto err_out_unlock;
-
/* get the CPU */
data = per_cpu(cpufreq_cpu_data, cpu);
@@ -167,13 +166,13 @@ static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
if (!sysfs && !kobject_get(&data->kobj))
goto err_out_put_module;
- read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ rcu_read_unlock();
return data;
err_out_put_module:
- module_put(cpufreq_driver->owner);
+ module_put(driver->owner);
err_out_unlock:
- read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ rcu_read_unlock();
err_out:
return NULL;
}
@@ -193,7 +192,7 @@ static void __cpufreq_cpu_put(struct cpufreq_policy *data, bool sysfs)
{
if (!sysfs)
kobject_put(&data->kobj);
- module_put(cpufreq_driver->owner);
+ module_put(rcu_dereference(cpufreq_driver)->owner);
}
void cpufreq_cpu_put(struct cpufreq_policy *data)
@@ -261,10 +260,13 @@ static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
{
struct cpufreq_policy *policy;
+ struct cpufreq_driver *driver;
BUG_ON(irqs_disabled());
- freqs->flags = cpufreq_driver->flags;
+ driver = rcu_dereference(cpufreq_driver);
+
+ freqs->flags = driver->flags;
pr_debug("notification %u of frequency transition to %u kHz\n",
state, freqs->new);
@@ -276,7 +278,7 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
* which is not equal to what the cpufreq core thinks is
* "old frequency".
*/
- if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
+ if (!(driver->flags & CPUFREQ_CONST_LOOPS)) {
if ((policy) && (policy->cpu == freqs->cpu) &&
(policy->cur) && (policy->cur != freqs->old)) {
pr_debug("Warning: CPU frequency is"
@@ -329,11 +331,12 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
struct cpufreq_governor **governor)
{
int err = -EINVAL;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
- if (!cpufreq_driver)
+ if (!driver)
goto out;
- if (cpufreq_driver->setpolicy) {
+ if (driver->setpolicy) {
if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
*policy = CPUFREQ_POLICY_PERFORMANCE;
err = 0;
@@ -342,7 +345,7 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
*policy = CPUFREQ_POLICY_POWERSAVE;
err = 0;
}
- } else if (cpufreq_driver->target) {
+ } else if (driver->target) {
struct cpufreq_governor *t;
mutex_lock(&cpufreq_governor_mutex);
@@ -493,7 +496,8 @@ static ssize_t store_scaling_governor(struct cpufreq_policy *policy,
*/
static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
{
- return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n", cpufreq_driver->name);
+ return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n",
+ rcu_dereference(cpufreq_driver)->name);
}
/**
@@ -505,7 +509,7 @@ static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
ssize_t i = 0;
struct cpufreq_governor *t;
- if (!cpufreq_driver->target) {
+ if (!rcu_dereference(cpufreq_driver)->target) {
i += sprintf(buf, "performance powersave");
goto out;
}
@@ -589,8 +593,10 @@ static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
{
unsigned int limit;
int ret;
- if (cpufreq_driver->bios_limit) {
- ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
+
+ if (driver->bios_limit) {
+ ret = driver->bios_limit(policy->cpu, &limit);
if (!ret)
return sprintf(buf, "%u\n", limit);
}
@@ -711,6 +717,7 @@ static int cpufreq_add_dev_policy(unsigned int cpu,
struct device *dev)
{
int ret = 0;
+ struct cpufreq_driver *driver;
#ifdef CONFIG_SMP
unsigned long flags;
unsigned int j;
@@ -724,6 +731,7 @@ static int cpufreq_add_dev_policy(unsigned int cpu,
policy->governor->name, cpu);
}
#endif
+ driver = rcu_dereference(cpufreq_driver);
for_each_cpu(j, policy->cpus) {
struct cpufreq_policy *managed_policy;
@@ -745,16 +753,16 @@ static int cpufreq_add_dev_policy(unsigned int cpu,
if (lock_policy_rwsem_write(cpu) < 0) {
/* Should not go through policy unlock path */
- if (cpufreq_driver->exit)
- cpufreq_driver->exit(policy);
+ if (driver->exit)
+ driver->exit(policy);
cpufreq_cpu_put(managed_policy);
return -EBUSY;
}
- write_lock_irqsave(&cpufreq_driver_lock, flags);
+ spin_lock_irqsave(&cpufreq_driver_lock, flags);
cpumask_copy(managed_policy->cpus, policy->cpus);
per_cpu(cpufreq_cpu_data, cpu) = managed_policy;
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
pr_debug("CPU already managed, adding link\n");
ret = sysfs_create_link(&dev->kobj,
@@ -767,8 +775,8 @@ static int cpufreq_add_dev_policy(unsigned int cpu,
* Call driver->exit() because only the cpu parent of
* the kobj needed to call init().
*/
- if (cpufreq_driver->exit)
- cpufreq_driver->exit(policy);
+ if (driver->exit)
+ driver->exit(policy);
if (!ret)
return 1;
@@ -819,6 +827,7 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
unsigned long flags;
int ret = 0;
unsigned int j;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
/* prepare interface data */
ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
@@ -827,37 +836,37 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
return ret;
/* set up files for this cpu device */
- drv_attr = cpufreq_driver->attr;
+ drv_attr = driver->attr;
while ((drv_attr) && (*drv_attr)) {
ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
if (ret)
goto err_out_kobj_put;
drv_attr++;
}
- if (cpufreq_driver->get) {
+ if (driver->get) {
ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
if (ret)
goto err_out_kobj_put;
}
- if (cpufreq_driver->target) {
+ if (driver->target) {
ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
if (ret)
goto err_out_kobj_put;
}
- if (cpufreq_driver->bios_limit) {
+ if (driver->bios_limit) {
ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
if (ret)
goto err_out_kobj_put;
}
- write_lock_irqsave(&cpufreq_driver_lock, flags);
+ spin_lock_irqsave(&cpufreq_driver_lock, flags);
for_each_cpu(j, policy->cpus) {
if (!cpu_online(j))
continue;
per_cpu(cpufreq_cpu_data, j) = policy;
per_cpu(cpufreq_policy_cpu, j) = policy->cpu;
}
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
ret = cpufreq_add_dev_symlink(cpu, policy);
if (ret)
@@ -874,8 +883,8 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
if (ret) {
pr_debug("setting policy failed\n");
- if (cpufreq_driver->exit)
- cpufreq_driver->exit(policy);
+ if (driver->exit)
+ driver->exit(policy);
}
return ret;
@@ -905,6 +914,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
#ifdef CONFIG_HOTPLUG_CPU
int sibling;
#endif
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
if (cpu_is_offline(cpu))
return 0;
@@ -921,7 +931,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
}
#endif
- if (!try_module_get(cpufreq_driver->owner)) {
+ if (!try_module_get(driver->owner)) {
ret = -EINVAL;
goto module_out;
}
@@ -965,7 +975,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
/* call driver. From then on the cpufreq must be able
* to accept all calls to ->verify and ->setpolicy for this CPU
*/
- ret = cpufreq_driver->init(policy);
+ ret = driver->init(policy);
if (ret) {
pr_debug("initialization failed\n");
goto err_unlock_policy;
@@ -992,17 +1002,17 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
unlock_policy_rwsem_write(cpu);
kobject_uevent(&policy->kobj, KOBJ_ADD);
- module_put(cpufreq_driver->owner);
+ module_put(driver->owner);
pr_debug("initialization complete\n");
return 0;
err_out_unregister:
- write_lock_irqsave(&cpufreq_driver_lock, flags);
+ spin_lock_irqsave(&cpufreq_driver_lock, flags);
for_each_cpu(j, policy->cpus)
per_cpu(cpufreq_cpu_data, j) = NULL;
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
kobject_put(&policy->kobj);
wait_for_completion(&policy->kobj_unregister);
@@ -1015,7 +1025,7 @@ err_free_cpumask:
err_free_policy:
kfree(policy);
nomem_out:
- module_put(cpufreq_driver->owner);
+ module_put(driver->owner);
module_out:
return ret;
}
@@ -1039,14 +1049,15 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
struct device *cpu_dev;
unsigned int j;
#endif
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
pr_debug("unregistering CPU %u\n", cpu);
- write_lock_irqsave(&cpufreq_driver_lock, flags);
+ spin_lock_irqsave(&cpufreq_driver_lock, flags);
data = per_cpu(cpufreq_cpu_data, cpu);
if (!data) {
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
unlock_policy_rwsem_write(cpu);
return -EINVAL;
}
@@ -1060,7 +1071,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
if (unlikely(cpu != data->cpu)) {
pr_debug("removing link\n");
cpumask_clear_cpu(cpu, data->cpus);
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
kobj = &dev->kobj;
cpufreq_cpu_put(data);
unlock_policy_rwsem_write(cpu);
@@ -1089,7 +1100,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
}
}
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
if (unlikely(cpumask_weight(data->cpus) > 1)) {
for_each_cpu(j, data->cpus) {
@@ -1109,10 +1120,10 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
}
}
#else
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
#endif
- if (cpufreq_driver->target)
+ if (driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
kobj = &data->kobj;
@@ -1129,8 +1140,8 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
pr_debug("wait complete\n");
lock_policy_rwsem_write(cpu);
- if (cpufreq_driver->exit)
- cpufreq_driver->exit(data);
+ if (driver->exit)
+ driver->exit(data);
unlock_policy_rwsem_write(cpu);
#ifdef CONFIG_HOTPLUG_CPU
@@ -1253,14 +1264,15 @@ static unsigned int __cpufreq_get(unsigned int cpu)
{
struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
unsigned int ret_freq = 0;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
- if (!cpufreq_driver->get)
+ if (!driver->get)
return ret_freq;
- ret_freq = cpufreq_driver->get(cpu);
+ ret_freq = driver->get(cpu);
if (ret_freq && policy->cur &&
- !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
+ !(driver->flags & CPUFREQ_CONST_LOOPS)) {
/* verify no discrepancy between actual and
saved value exists */
if (unlikely(ret_freq != policy->cur)) {
@@ -1320,6 +1332,7 @@ static int cpufreq_bp_suspend(void)
int cpu = smp_processor_id();
struct cpufreq_policy *cpu_policy;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
pr_debug("suspending cpu %u\n", cpu);
@@ -1328,8 +1341,8 @@ static int cpufreq_bp_suspend(void)
if (!cpu_policy)
return 0;
- if (cpufreq_driver->suspend) {
- ret = cpufreq_driver->suspend(cpu_policy);
+ if (driver->suspend) {
+ ret = driver->suspend(cpu_policy);
if (ret)
printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
"step on CPU %u\n", cpu_policy->cpu);
@@ -1358,6 +1371,7 @@ static void cpufreq_bp_resume(void)
int cpu = smp_processor_id();
struct cpufreq_policy *cpu_policy;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
pr_debug("resuming cpu %u\n", cpu);
@@ -1366,8 +1380,8 @@ static void cpufreq_bp_resume(void)
if (!cpu_policy)
return;
- if (cpufreq_driver->resume) {
- ret = cpufreq_driver->resume(cpu_policy);
+ if (driver->resume) {
+ ret = driver->resume(cpu_policy);
if (ret) {
printk(KERN_ERR "cpufreq: resume failed in ->resume "
"step on CPU %u\n", cpu_policy->cpu);
@@ -1471,6 +1485,7 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
{
int retval = -EINVAL;
unsigned int old_target_freq = target_freq;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
if (cpufreq_disabled())
return -ENODEV;
@@ -1487,8 +1502,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
if (target_freq == policy->cur)
return 0;
- if (cpu_online(policy->cpu) && cpufreq_driver->target)
- retval = cpufreq_driver->target(policy, target_freq, relation);
+ if (cpu_online(policy->cpu) && driver->target)
+ retval = driver->target(policy, target_freq, relation);
return retval;
}
@@ -1521,15 +1536,16 @@ EXPORT_SYMBOL_GPL(cpufreq_driver_target);
int __cpufreq_driver_getavg(struct cpufreq_policy *policy, unsigned int cpu)
{
int ret = 0;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
- if (!(cpu_online(cpu) && cpufreq_driver->getavg))
+ if (!(cpu_online(cpu) && driver->getavg))
return 0;
policy = cpufreq_cpu_get(policy->cpu);
if (!policy)
return -EINVAL;
- ret = cpufreq_driver->getavg(policy, cpu);
+ ret = driver->getavg(policy, cpu);
cpufreq_cpu_put(policy);
return ret;
@@ -1679,6 +1695,7 @@ static int __cpufreq_set_policy(struct cpufreq_policy *data,
struct cpufreq_policy *policy)
{
int ret = 0;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
pr_debug("setting new policy for CPU %u: %u - %u kHz\n", policy->cpu,
policy->min, policy->max);
@@ -1692,7 +1709,7 @@ static int __cpufreq_set_policy(struct cpufreq_policy *data,
}
/* verify the cpu speed can be set within this limit */
- ret = cpufreq_driver->verify(policy);
+ ret = driver->verify(policy);
if (ret)
goto error_out;
@@ -1706,7 +1723,7 @@ static int __cpufreq_set_policy(struct cpufreq_policy *data,
/* verify the cpu speed can be set within this limit,
which might be different to the first one */
- ret = cpufreq_driver->verify(policy);
+ ret = driver->verify(policy);
if (ret)
goto error_out;
@@ -1720,10 +1737,10 @@ static int __cpufreq_set_policy(struct cpufreq_policy *data,
pr_debug("new min and max freqs are %u - %u kHz\n",
data->min, data->max);
- if (cpufreq_driver->setpolicy) {
+ if (driver->setpolicy) {
data->policy = policy->policy;
pr_debug("setting range\n");
- ret = cpufreq_driver->setpolicy(policy);
+ ret = driver->setpolicy(policy);
} else {
if (policy->governor != data->governor) {
/* save old, working values */
@@ -1771,6 +1788,7 @@ int cpufreq_update_policy(unsigned int cpu)
struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
struct cpufreq_policy policy;
int ret;
+ struct cpufreq_driver *driver = rcu_dereference(cpufreq_driver);
if (!data) {
ret = -ENODEV;
@@ -1791,8 +1809,8 @@ int cpufreq_update_policy(unsigned int cpu)
/* BIOS might change freq behind our back
-> ask driver for current freq and notify governors about a change */
- if (cpufreq_driver->get) {
- policy.cur = cpufreq_driver->get(cpu);
+ if (driver->get) {
+ policy.cur = driver->get(cpu);
if (!data->cur) {
pr_debug("Driver did not initialize current freq");
data->cur = policy.cur;
@@ -1878,19 +1896,19 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
if (driver_data->setpolicy)
driver_data->flags |= CPUFREQ_CONST_LOOPS;
- write_lock_irqsave(&cpufreq_driver_lock, flags);
- if (cpufreq_driver) {
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_lock_irqsave(&cpufreq_driver_lock, flags);
+ if (rcu_dereference(cpufreq_driver)) {
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
return -EBUSY;
}
- cpufreq_driver = driver_data;
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ rcu_assign_pointer(cpufreq_driver, driver_data);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
ret = subsys_interface_register(&cpufreq_interface);
if (ret)
goto err_null_driver;
- if (!(cpufreq_driver->flags & CPUFREQ_STICKY)) {
+ if (!(rcu_dereference(cpufreq_driver)->flags & CPUFREQ_STICKY)) {
int i;
ret = -ENODEV;
@@ -1916,9 +1934,9 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
err_if_unreg:
subsys_interface_unregister(&cpufreq_interface);
err_null_driver:
- write_lock_irqsave(&cpufreq_driver_lock, flags);
- cpufreq_driver = NULL;
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_lock_irqsave(&cpufreq_driver_lock, flags);
+ rcu_assign_pointer(cpufreq_driver, NULL);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(cpufreq_register_driver);
@@ -1935,8 +1953,9 @@ EXPORT_SYMBOL_GPL(cpufreq_register_driver);
int cpufreq_unregister_driver(struct cpufreq_driver *driver)
{
unsigned long flags;
+ struct cpufreq_driver *old_driver = rcu_dereference(cpufreq_driver);
- if (!cpufreq_driver || (driver != cpufreq_driver))
+ if (!old_driver || (driver != old_driver))
return -EINVAL;
pr_debug("unregistering driver %s\n", driver->name);
@@ -1944,9 +1963,9 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
subsys_interface_unregister(&cpufreq_interface);
unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
- write_lock_irqsave(&cpufreq_driver_lock, flags);
- cpufreq_driver = NULL;
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ spin_lock_irqsave(&cpufreq_driver_lock, flags);
+ rcu_assign_pointer(cpufreq_driver, NULL);
+ spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
return 0;
}
--
1.8.0.1
--
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