cpufreq: Revert incorrect commit 5800043
Commit 5800043 (cpufreq: convert cpufreq_driver to using RCU) causes
the following call trace to be spit on boot:
BUG: sleeping function called from invalid context at /scratch/rafael/work/linux-pm/mm/slab.c:3179
in_atomic(): 0, irqs_disabled(): 0, pid: 292, name: systemd-udevd
2 locks held by systemd-udevd/292:
#0: (subsys mutex){+.+.+.}, at: [<ffffffff8146851a>] subsys_interface_register+0x4a/0xe0
#1: (rcu_read_lock){.+.+.+}, at: [<ffffffff81538210>] cpufreq_add_dev_interface+0x60/0x5e0
Pid: 292, comm: systemd-udevd Not tainted 3.9.0-rc8+ #323
Call Trace:
[<ffffffff81072c90>] __might_sleep+0x140/0x1f0
[<ffffffff811581c2>] kmem_cache_alloc+0x42/0x2b0
[<ffffffff811e7179>] sysfs_new_dirent+0x59/0x130
[<ffffffff811e63cb>] sysfs_add_file_mode+0x6b/0x110
[<ffffffff81538210>] ? cpufreq_add_dev_interface+0x60/0x5e0
[<ffffffff810a3254>] ? __lock_is_held+0x54/0x80
[<ffffffff811e647d>] sysfs_add_file+0xd/0x10
[<ffffffff811e6541>] sysfs_create_file+0x21/0x30
[<ffffffff81538280>] cpufreq_add_dev_interface+0xd0/0x5e0
[<ffffffff81538210>] ? cpufreq_add_dev_interface+0x60/0x5e0
[<ffffffffa000337f>] ? acpi_processor_get_platform_limit+0x32/0xbb [processor]
[<ffffffffa022f540>] ? do_drv_write+0x70/0x70 [acpi_cpufreq]
[<ffffffff810a3254>] ? __lock_is_held+0x54/0x80
[<ffffffff8106c97e>] ? up_read+0x1e/0x40
[<ffffffff8106e632>] ? __blocking_notifier_call_chain+0x72/0xc0
[<ffffffff81538dbd>] cpufreq_add_dev+0x62d/0xae0
[<ffffffff815389b8>] ? cpufreq_add_dev+0x228/0xae0
[<ffffffff81468569>] subsys_interface_register+0x99/0xe0
[<ffffffffa014d000>] ? 0xffffffffa014cfff
[<ffffffff81535d5d>] cpufreq_register_driver+0x9d/0x200
[<ffffffffa014d000>] ? 0xffffffffa014cfff
[<ffffffffa014d0e9>] acpi_cpufreq_init+0xe9/0x1000 [acpi_cpufreq]
[<ffffffff810002fa>] do_one_initcall+0x11a/0x170
[<ffffffff810b4b87>] load_module+0x1cf7/0x2920
[<ffffffff81322580>] ? ddebug_proc_open+0xb0/0xb0
[<ffffffff816baee0>] ? retint_restore_args+0xe/0xe
[<ffffffff810b5887>] sys_init_module+0xd7/0x120
[<ffffffff816bb6d2>] system_call_fastpath+0x16/0x1b
which is quite obvious, because that commit put (multiple instances
of) sysfs_create_file() under rcu_read_lock()/rcu_read_unlock(),
although sysfs_create_file() may cause memory to be allocated with
GFP_KERNEL and that may sleep, which is not permitted in RCU read
critical section.
Revert the buggy commit altogether along with some changes on top
of it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a6f6595..1b8a48e 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -39,7 +39,7 @@
* level driver of CPUFreq support, and its spinlock. This lock
* also protects the cpufreq_cpu_data array.
*/
-static struct cpufreq_driver __rcu *cpufreq_driver;
+static struct cpufreq_driver *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 */
@@ -130,35 +130,27 @@
bool have_governor_per_policy(void)
{
- bool have_governor_per_policy;
- rcu_read_lock();
- have_governor_per_policy =
- rcu_dereference(cpufreq_driver)->have_governor_per_policy;
- rcu_read_unlock();
- return have_governor_per_policy;
+ return cpufreq_driver->have_governor_per_policy;
}
static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
{
struct cpufreq_policy *data;
- struct cpufreq_driver *driver;
unsigned long flags;
if (cpu >= nr_cpu_ids)
goto err_out;
/* get the cpufreq driver */
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
-
- if (!driver)
- goto err_out_unlock;
-
- if (!try_module_get(driver->owner))
- goto err_out_unlock;
-
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;
+
+
/* get the CPU */
data = per_cpu(cpufreq_cpu_data, cpu);
@@ -169,14 +161,12 @@
goto err_out_put_module;
read_unlock_irqrestore(&cpufreq_driver_lock, flags);
- rcu_read_unlock();
return data;
err_out_put_module:
- module_put(driver->owner);
- read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ module_put(cpufreq_driver->owner);
err_out_unlock:
- rcu_read_unlock();
+ read_unlock_irqrestore(&cpufreq_driver_lock, flags);
err_out:
return NULL;
}
@@ -199,9 +189,7 @@
{
if (!sysfs)
kobject_put(&data->kobj);
- rcu_read_lock();
- module_put(rcu_dereference(cpufreq_driver)->owner);
- rcu_read_unlock();
+ module_put(cpufreq_driver->owner);
}
void cpufreq_cpu_put(struct cpufreq_policy *data)
@@ -269,9 +257,7 @@
if (cpufreq_disabled())
return;
- rcu_read_lock();
- freqs->flags = rcu_dereference(cpufreq_driver)->flags;
- rcu_read_unlock();
+ freqs->flags = cpufreq_driver->flags;
pr_debug("notification %u of frequency transition to %u kHz\n",
state, freqs->new);
@@ -282,7 +268,7 @@
* which is not equal to what the cpufreq core thinks is
* "old frequency".
*/
- if (!(freqs->flags & CPUFREQ_CONST_LOOPS)) {
+ if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
if ((policy) && (policy->cpu == freqs->cpu) &&
(policy->cur) && (policy->cur != freqs->old)) {
pr_debug("Warning: CPU frequency is"
@@ -348,21 +334,11 @@
struct cpufreq_governor **governor)
{
int err = -EINVAL;
- struct cpufreq_driver *driver;
- bool has_setpolicy;
- bool has_target;
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
- if (!driver) {
- rcu_read_unlock();
+ if (!cpufreq_driver)
goto out;
- }
- has_setpolicy = driver->setpolicy ? true : false;
- has_target = driver->target ? true : false;
- rcu_read_unlock();
- if (has_setpolicy) {
+ if (cpufreq_driver->setpolicy) {
if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
*policy = CPUFREQ_POLICY_PERFORMANCE;
err = 0;
@@ -371,7 +347,7 @@
*policy = CPUFREQ_POLICY_POWERSAVE;
err = 0;
}
- } else if (has_target) {
+ } else if (cpufreq_driver->target) {
struct cpufreq_governor *t;
mutex_lock(&cpufreq_governor_mutex);
@@ -522,12 +498,7 @@
*/
static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
{
- ssize_t size;
- rcu_read_lock();
- size = scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n",
- rcu_dereference(cpufreq_driver)->name);
- rcu_read_unlock();
- return size;
+ return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n", cpufreq_driver->name);
}
/**
@@ -539,13 +510,10 @@
ssize_t i = 0;
struct cpufreq_governor *t;
- rcu_read_lock();
- if (!rcu_dereference(cpufreq_driver)->target) {
- rcu_read_unlock();
+ if (!cpufreq_driver->target) {
i += sprintf(buf, "performance powersave");
goto out;
}
- rcu_read_unlock();
list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
@@ -623,15 +591,9 @@
static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
{
unsigned int limit;
- int (*bios_limit)(int cpu, unsigned int *limit);
int ret;
-
- rcu_read_lock();
- bios_limit = rcu_dereference(cpufreq_driver)->bios_limit;
- rcu_read_unlock();
-
- if (bios_limit) {
- ret = bios_limit(policy->cpu, &limit);
+ if (cpufreq_driver->bios_limit) {
+ ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
if (!ret)
return sprintf(buf, "%u\n", limit);
}
@@ -774,7 +736,6 @@
{
struct cpufreq_policy new_policy;
struct freq_attr **drv_attr;
- struct cpufreq_driver *driver;
unsigned long flags;
int ret = 0;
unsigned int j;
@@ -786,31 +747,28 @@
return ret;
/* set up files for this cpu device */
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
- drv_attr = driver->attr;
+ drv_attr = cpufreq_driver->attr;
while ((drv_attr) && (*drv_attr)) {
ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
if (ret)
- goto err_out_unlock;
+ goto err_out_kobj_put;
drv_attr++;
}
- if (driver->get) {
+ if (cpufreq_driver->get) {
ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
if (ret)
- goto err_out_unlock;
+ goto err_out_kobj_put;
}
- if (driver->target) {
+ if (cpufreq_driver->target) {
ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
if (ret)
- goto err_out_unlock;
+ goto err_out_kobj_put;
}
- if (driver->bios_limit) {
+ if (cpufreq_driver->bios_limit) {
ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
if (ret)
- goto err_out_unlock;
+ goto err_out_kobj_put;
}
- rcu_read_unlock();
write_lock_irqsave(&cpufreq_driver_lock, flags);
for_each_cpu(j, policy->cpus) {
@@ -833,20 +791,12 @@
policy->user_policy.governor = policy->governor;
if (ret) {
- int (*exit)(struct cpufreq_policy *policy);
-
pr_debug("setting policy failed\n");
- rcu_read_lock();
- exit = rcu_dereference(cpufreq_driver)->exit;
- rcu_read_unlock();
- if (exit)
- exit(policy);
-
+ if (cpufreq_driver->exit)
+ cpufreq_driver->exit(policy);
}
return ret;
-err_out_unlock:
- rcu_read_unlock();
err_out_kobj_put:
kobject_put(&policy->kobj);
wait_for_completion(&policy->kobj_unregister);
@@ -858,16 +808,12 @@
struct device *dev)
{
struct cpufreq_policy *policy;
- int ret = 0, has_target = 0;
+ int ret = 0, has_target = !!cpufreq_driver->target;
unsigned long flags;
policy = cpufreq_cpu_get(sibling);
WARN_ON(!policy);
- rcu_read_lock();
- has_target = !!rcu_dereference(cpufreq_driver)->target;
- rcu_read_unlock();
-
if (has_target)
__cpufreq_governor(policy, CPUFREQ_GOV_STOP);
@@ -911,8 +857,6 @@
unsigned int j, cpu = dev->id;
int ret = -ENOMEM;
struct cpufreq_policy *policy;
- struct cpufreq_driver *driver;
- int (*init)(struct cpufreq_policy *policy);
unsigned long flags;
#ifdef CONFIG_HOTPLUG_CPU
struct cpufreq_governor *gov;
@@ -947,15 +891,10 @@
#endif
#endif
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
- if (!try_module_get(driver->owner)) {
- rcu_read_unlock();
+ if (!try_module_get(cpufreq_driver->owner)) {
ret = -EINVAL;
goto module_out;
}
- init = driver->init;
- rcu_read_unlock();
policy = kzalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
if (!policy)
@@ -980,7 +919,7 @@
/* call driver. From then on the cpufreq must be able
* to accept all calls to ->verify and ->setpolicy for this CPU
*/
- ret = init(policy);
+ ret = cpufreq_driver->init(policy);
if (ret) {
pr_debug("initialization failed\n");
goto err_set_policy_cpu;
@@ -1015,9 +954,7 @@
goto err_out_unregister;
kobject_uevent(&policy->kobj, KOBJ_ADD);
- rcu_read_lock();
- module_put(rcu_dereference(cpufreq_driver)->owner);
- rcu_read_unlock();
+ module_put(cpufreq_driver->owner);
pr_debug("initialization complete\n");
return 0;
@@ -1039,9 +976,7 @@
err_free_policy:
kfree(policy);
nomem_out:
- rcu_read_lock();
- module_put(rcu_dereference(cpufreq_driver)->owner);
- rcu_read_unlock();
+ module_put(cpufreq_driver->owner);
module_out:
return ret;
}
@@ -1075,12 +1010,9 @@
unsigned int cpu = dev->id, ret, cpus;
unsigned long flags;
struct cpufreq_policy *data;
- struct cpufreq_driver *driver;
struct kobject *kobj;
struct completion *cmp;
struct device *cpu_dev;
- bool has_target;
- int (*exit)(struct cpufreq_policy *policy);
pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
@@ -1096,19 +1028,14 @@
return -EINVAL;
}
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
- has_target = driver->target ? true : false;
- exit = driver->exit;
- if (has_target)
+ if (cpufreq_driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
#ifdef CONFIG_HOTPLUG_CPU
- if (!driver->setpolicy)
+ if (!cpufreq_driver->setpolicy)
strncpy(per_cpu(cpufreq_cpu_governor, cpu),
data->governor->name, CPUFREQ_NAME_LEN);
#endif
- rcu_read_unlock();
WARN_ON(lock_policy_rwsem_write(cpu));
cpus = cpumask_weight(data->cpus);
@@ -1153,7 +1080,7 @@
/* If cpu is last user of policy, free policy */
if (cpus == 1) {
- if (has_target)
+ if (cpufreq_driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT);
lock_policy_rwsem_read(cpu);
@@ -1170,13 +1097,13 @@
wait_for_completion(cmp);
pr_debug("wait complete\n");
- if (exit)
- exit(data);
+ if (cpufreq_driver->exit)
+ cpufreq_driver->exit(data);
free_cpumask_var(data->related_cpus);
free_cpumask_var(data->cpus);
kfree(data);
- } else if (has_target) {
+ } else if (cpufreq_driver->target) {
__cpufreq_governor(data, CPUFREQ_GOV_START);
__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
}
@@ -1250,18 +1177,10 @@
unsigned int cpufreq_quick_get(unsigned int cpu)
{
struct cpufreq_policy *policy;
- struct cpufreq_driver *driver;
- unsigned int (*get)(unsigned int cpu);
unsigned int ret_freq = 0;
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
- if (driver && driver->setpolicy && driver->get) {
- get = driver->get;
- rcu_read_unlock();
- return get(cpu);
- }
- rcu_read_unlock();
+ if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get)
+ return cpufreq_driver->get(cpu);
policy = cpufreq_cpu_get(cpu);
if (policy) {
@@ -1297,26 +1216,15 @@
static unsigned int __cpufreq_get(unsigned int cpu)
{
struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
- struct cpufreq_driver *driver;
- unsigned int (*get)(unsigned int cpu);
unsigned int ret_freq = 0;
- u8 flags;
-
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
- if (!driver->get) {
- rcu_read_unlock();
+ if (!cpufreq_driver->get)
return ret_freq;
- }
- flags = driver->flags;
- get = driver->get;
- rcu_read_unlock();
- ret_freq = get(cpu);
+ ret_freq = cpufreq_driver->get(cpu);
if (ret_freq && policy->cur &&
- !(flags & CPUFREQ_CONST_LOOPS)) {
+ !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
/* verify no discrepancy between actual and
saved value exists */
if (unlikely(ret_freq != policy->cur)) {
@@ -1372,7 +1280,6 @@
*/
static int cpufreq_bp_suspend(void)
{
- int (*suspend)(struct cpufreq_policy *policy);
int ret = 0;
int cpu = smp_processor_id();
@@ -1385,11 +1292,8 @@
if (!cpu_policy)
return 0;
- rcu_read_lock();
- suspend = rcu_dereference(cpufreq_driver)->suspend;
- rcu_read_unlock();
- if (suspend) {
- ret = suspend(cpu_policy);
+ if (cpufreq_driver->suspend) {
+ ret = cpufreq_driver->suspend(cpu_policy);
if (ret)
printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
"step on CPU %u\n", cpu_policy->cpu);
@@ -1415,7 +1319,6 @@
static void cpufreq_bp_resume(void)
{
int ret = 0;
- int (*resume)(struct cpufreq_policy *policy);
int cpu = smp_processor_id();
struct cpufreq_policy *cpu_policy;
@@ -1427,12 +1330,8 @@
if (!cpu_policy)
return;
- rcu_read_lock();
- resume = rcu_dereference(cpufreq_driver)->resume;
- rcu_read_unlock();
-
- if (resume) {
- ret = resume(cpu_policy);
+ if (cpufreq_driver->resume) {
+ ret = cpufreq_driver->resume(cpu_policy);
if (ret) {
printk(KERN_ERR "cpufreq: resume failed in ->resume "
"step on CPU %u\n", cpu_policy->cpu);
@@ -1459,14 +1358,10 @@
*/
const char *cpufreq_get_current_driver(void)
{
- struct cpufreq_driver *driver;
- const char *name = NULL;
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
- if (driver)
- name = driver->name;
- rcu_read_unlock();
- return name;
+ if (cpufreq_driver)
+ return cpufreq_driver->name;
+
+ return NULL;
}
EXPORT_SYMBOL_GPL(cpufreq_get_current_driver);
@@ -1560,9 +1455,6 @@
{
int retval = -EINVAL;
unsigned int old_target_freq = target_freq;
- int (*target)(struct cpufreq_policy *policy,
- unsigned int target_freq,
- unsigned int relation);
if (cpufreq_disabled())
return -ENODEV;
@@ -1579,11 +1471,8 @@
if (target_freq == policy->cur)
return 0;
- rcu_read_lock();
- target = rcu_dereference(cpufreq_driver)->target;
- rcu_read_unlock();
- if (target)
- retval = target(policy, target_freq, relation);
+ if (cpufreq_driver->target)
+ retval = cpufreq_driver->target(policy, target_freq, relation);
return retval;
}
@@ -1616,24 +1505,18 @@
int __cpufreq_driver_getavg(struct cpufreq_policy *policy, unsigned int cpu)
{
int ret = 0;
- unsigned int (*getavg)(struct cpufreq_policy *policy,
- unsigned int cpu);
if (cpufreq_disabled())
return ret;
- rcu_read_lock();
- getavg = rcu_dereference(cpufreq_driver)->getavg;
- rcu_read_unlock();
-
- if (!getavg)
+ if (!cpufreq_driver->getavg)
return 0;
policy = cpufreq_cpu_get(policy->cpu);
if (!policy)
return -EINVAL;
- ret = getavg(policy, cpu);
+ ret = cpufreq_driver->getavg(policy, cpu);
cpufreq_cpu_put(policy);
return ret;
@@ -1791,9 +1674,6 @@
struct cpufreq_policy *policy)
{
int ret = 0, failed = 1;
- struct cpufreq_driver *driver;
- int (*verify)(struct cpufreq_policy *policy);
- int (*setpolicy)(struct cpufreq_policy *policy);
pr_debug("setting new policy for CPU %u: %u - %u kHz\n", policy->cpu,
policy->min, policy->max);
@@ -1807,13 +1687,7 @@
}
/* verify the cpu speed can be set within this limit */
- rcu_read_lock();
- driver = rcu_dereference(cpufreq_driver);
- verify = driver->verify;
- setpolicy = driver->setpolicy;
- rcu_read_unlock();
-
- ret = verify(policy);
+ ret = cpufreq_driver->verify(policy);
if (ret)
goto error_out;
@@ -1827,7 +1701,7 @@
/* verify the cpu speed can be set within this limit,
which might be different to the first one */
- ret = verify(policy);
+ ret = cpufreq_driver->verify(policy);
if (ret)
goto error_out;
@@ -1841,10 +1715,10 @@
pr_debug("new min and max freqs are %u - %u kHz\n",
data->min, data->max);
- if (setpolicy) {
+ if (cpufreq_driver->setpolicy) {
data->policy = policy->policy;
pr_debug("setting range\n");
- ret = setpolicy(policy);
+ ret = cpufreq_driver->setpolicy(policy);
} else {
if (policy->governor != data->governor) {
/* save old, working values */
@@ -1904,11 +1778,6 @@
{
struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
struct cpufreq_policy policy;
- struct cpufreq_driver *driver;
- unsigned int (*get)(unsigned int cpu);
- int (*target)(struct cpufreq_policy *policy,
- unsigned int target_freq,
- unsigned int relation);
int ret;
if (!data) {
@@ -1930,18 +1799,13 @@
/* BIOS might change freq behind our back
-> ask driver for current freq and notify governors about a change */
- rcu_read_lock();
- driver = rcu_access_pointer(cpufreq_driver);
- get = driver->get;
- target = driver->target;
- rcu_read_unlock();
- if (get) {
- policy.cur = get(cpu);
+ if (cpufreq_driver->get) {
+ policy.cur = cpufreq_driver->get(cpu);
if (!data->cur) {
pr_debug("Driver did not initialize current freq");
data->cur = policy.cur;
} else {
- if (data->cur != policy.cur && target)
+ if (data->cur != policy.cur && cpufreq_driver->target)
cpufreq_out_of_sync(cpu, data->cur,
policy.cur);
}
@@ -2020,19 +1884,18 @@
driver_data->flags |= CPUFREQ_CONST_LOOPS;
write_lock_irqsave(&cpufreq_driver_lock, flags);
- if (rcu_access_pointer(cpufreq_driver)) {
+ if (cpufreq_driver) {
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
return -EBUSY;
}
- rcu_assign_pointer(cpufreq_driver, driver_data);
+ cpufreq_driver = driver_data;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
- synchronize_rcu();
ret = subsys_interface_register(&cpufreq_interface);
if (ret)
goto err_null_driver;
- if (!(driver_data->flags & CPUFREQ_STICKY)) {
+ if (!(cpufreq_driver->flags & CPUFREQ_STICKY)) {
int i;
ret = -ENODEV;
@@ -2059,9 +1922,8 @@
subsys_interface_unregister(&cpufreq_interface);
err_null_driver:
write_lock_irqsave(&cpufreq_driver_lock, flags);
- rcu_assign_pointer(cpufreq_driver, NULL);
+ cpufreq_driver = NULL;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
- synchronize_rcu();
return ret;
}
EXPORT_SYMBOL_GPL(cpufreq_register_driver);
@@ -2078,15 +1940,9 @@
int cpufreq_unregister_driver(struct cpufreq_driver *driver)
{
unsigned long flags;
- struct cpufreq_driver *old_driver;
- rcu_read_lock();
- old_driver = rcu_access_pointer(cpufreq_driver);
- if (!old_driver || (driver != old_driver)) {
- rcu_read_unlock();
+ if (!cpufreq_driver || (driver != cpufreq_driver))
return -EINVAL;
- }
- rcu_read_unlock();
pr_debug("unregistering driver %s\n", driver->name);
@@ -2094,9 +1950,8 @@
unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
write_lock_irqsave(&cpufreq_driver_lock, flags);
- rcu_assign_pointer(cpufreq_driver, NULL);
+ cpufreq_driver = NULL;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
- synchronize_rcu();
return 0;
}