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cpufreq: convert cpufreq_driver to using RCU
We eventually would like to remove the rwlock cpufreq_driver_lock or convert it back to a spinlock and protect the read sections with RCU. The first step in that direction is to make cpufreq_driver use RCU. I don't see an easy wasy to protect the cpufreq_cpu_data structure with RCU, so I am leaving it with the rwlock for now since under certain configs __cpufreq_cpu_get is a hot spot with 256+ cores. [rjw: Subject, changelog, white space] Signed-off-by: Nathan Zimmer <nzimmer@sgi.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Nathan Zimmer
Rafael J. Wysocki
parent
6eb1c37742
commit
5800043b24
@ -39,7 +39,7 @@
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* level driver of CPUFreq support, and its spinlock. This lock
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* also protects the cpufreq_cpu_data array.
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*/
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static struct cpufreq_driver *cpufreq_driver;
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static struct cpufreq_driver __rcu *cpufreq_driver;
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static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
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#ifdef CONFIG_HOTPLUG_CPU
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/* This one keeps track of the previously set governor of a removed CPU */
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@ -130,27 +130,35 @@ static DEFINE_MUTEX(cpufreq_governor_mutex);
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bool have_governor_per_policy(void)
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{
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return cpufreq_driver->have_governor_per_policy;
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bool have_governor_per_policy;
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rcu_read_lock();
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have_governor_per_policy =
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rcu_dereference(cpufreq_driver)->have_governor_per_policy;
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rcu_read_unlock();
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return have_governor_per_policy;
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}
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static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
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{
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struct cpufreq_policy *data;
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struct cpufreq_driver *driver;
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unsigned long flags;
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if (cpu >= nr_cpu_ids)
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goto err_out;
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/* get the cpufreq driver */
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rcu_read_lock();
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driver = rcu_dereference(cpufreq_driver);
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if (!driver)
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goto err_out_unlock;
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if (!try_module_get(driver->owner))
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goto err_out_unlock;
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read_lock_irqsave(&cpufreq_driver_lock, flags);
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if (!cpufreq_driver)
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goto err_out_unlock;
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if (!try_module_get(cpufreq_driver->owner))
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goto err_out_unlock;
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/* get the CPU */
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data = per_cpu(cpufreq_cpu_data, cpu);
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@ -161,12 +169,14 @@ static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
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goto err_out_put_module;
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read_unlock_irqrestore(&cpufreq_driver_lock, flags);
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rcu_read_unlock();
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return data;
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err_out_put_module:
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module_put(cpufreq_driver->owner);
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err_out_unlock:
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module_put(driver->owner);
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read_unlock_irqrestore(&cpufreq_driver_lock, flags);
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err_out_unlock:
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rcu_read_unlock();
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err_out:
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return NULL;
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}
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@ -189,7 +199,9 @@ static void __cpufreq_cpu_put(struct cpufreq_policy *data, bool sysfs)
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{
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if (!sysfs)
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kobject_put(&data->kobj);
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module_put(cpufreq_driver->owner);
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rcu_read_lock();
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module_put(rcu_dereference(cpufreq_driver)->owner);
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rcu_read_unlock();
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}
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void cpufreq_cpu_put(struct cpufreq_policy *data)
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@ -257,7 +269,9 @@ void __cpufreq_notify_transition(struct cpufreq_policy *policy,
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if (cpufreq_disabled())
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return;
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freqs->flags = cpufreq_driver->flags;
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rcu_read_lock();
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freqs->flags = rcu_dereference(cpufreq_driver)->flags;
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rcu_read_unlock();
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pr_debug("notification %u of frequency transition to %u kHz\n",
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state, freqs->new);
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@ -268,7 +282,7 @@ void __cpufreq_notify_transition(struct cpufreq_policy *policy,
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* which is not equal to what the cpufreq core thinks is
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* "old frequency".
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*/
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if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
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if (!(freqs->flags & CPUFREQ_CONST_LOOPS)) {
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if ((policy) && (policy->cpu == freqs->cpu) &&
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(policy->cur) && (policy->cur != freqs->old)) {
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pr_debug("Warning: CPU frequency is"
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@ -334,11 +348,21 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
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struct cpufreq_governor **governor)
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{
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int err = -EINVAL;
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struct cpufreq_driver *driver;
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bool has_setpolicy;
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bool has_target;
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if (!cpufreq_driver)
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rcu_read_lock();
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driver = rcu_dereference(cpufreq_driver);
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if (!driver) {
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rcu_read_unlock();
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goto out;
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}
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has_setpolicy = driver->setpolicy ? true : false;
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has_target = driver->target ? true : false;
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rcu_read_unlock();
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if (cpufreq_driver->setpolicy) {
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if (has_setpolicy) {
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if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
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*policy = CPUFREQ_POLICY_PERFORMANCE;
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err = 0;
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@ -347,7 +371,7 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
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*policy = CPUFREQ_POLICY_POWERSAVE;
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err = 0;
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}
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} else if (cpufreq_driver->target) {
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} else if (has_target) {
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struct cpufreq_governor *t;
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mutex_lock(&cpufreq_governor_mutex);
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@ -498,7 +522,12 @@ static ssize_t store_scaling_governor(struct cpufreq_policy *policy,
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*/
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static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
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{
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return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n", cpufreq_driver->name);
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ssize_t size;
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rcu_read_lock();
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size = scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n",
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rcu_dereference(cpufreq_driver)->name);
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rcu_read_unlock();
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return size;
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}
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/**
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@ -510,10 +539,13 @@ static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
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ssize_t i = 0;
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struct cpufreq_governor *t;
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if (!cpufreq_driver->target) {
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rcu_read_lock();
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if (!rcu_dereference(cpufreq_driver)->target) {
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rcu_read_unlock();
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i += sprintf(buf, "performance powersave");
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goto out;
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}
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rcu_read_unlock();
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list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
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if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
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@ -591,9 +623,15 @@ static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
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static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
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{
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unsigned int limit;
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int (*bios_limit)(int cpu, unsigned int *limit);
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int ret;
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if (cpufreq_driver->bios_limit) {
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ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
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rcu_read_lock();
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bios_limit = rcu_dereference(cpufreq_driver)->bios_limit;
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rcu_read_unlock();
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if (bios_limit) {
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ret = bios_limit(policy->cpu, &limit);
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if (!ret)
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return sprintf(buf, "%u\n", limit);
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}
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@ -736,6 +774,7 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
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{
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struct cpufreq_policy new_policy;
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struct freq_attr **drv_attr;
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struct cpufreq_driver *driver;
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unsigned long flags;
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int ret = 0;
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unsigned int j;
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@ -747,28 +786,31 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
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return ret;
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/* set up files for this cpu device */
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drv_attr = cpufreq_driver->attr;
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rcu_read_lock();
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driver = rcu_dereference(cpufreq_driver);
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drv_attr = driver->attr;
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while ((drv_attr) && (*drv_attr)) {
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ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
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if (ret)
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goto err_out_kobj_put;
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goto err_out_unlock;
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drv_attr++;
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}
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if (cpufreq_driver->get) {
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if (driver->get) {
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ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
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if (ret)
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goto err_out_kobj_put;
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goto err_out_unlock;
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}
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if (cpufreq_driver->target) {
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if (driver->target) {
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ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
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if (ret)
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goto err_out_kobj_put;
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goto err_out_unlock;
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}
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if (cpufreq_driver->bios_limit) {
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if (driver->bios_limit) {
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ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
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if (ret)
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goto err_out_kobj_put;
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goto err_out_unlock;
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}
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rcu_read_unlock();
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write_lock_irqsave(&cpufreq_driver_lock, flags);
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for_each_cpu(j, policy->cpus) {
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@ -791,12 +833,20 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
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policy->user_policy.governor = policy->governor;
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if (ret) {
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int (*exit)(struct cpufreq_policy *policy);
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pr_debug("setting policy failed\n");
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if (cpufreq_driver->exit)
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cpufreq_driver->exit(policy);
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rcu_read_lock();
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exit = rcu_dereference(cpufreq_driver)->exit;
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rcu_read_unlock();
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if (exit)
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exit(policy);
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}
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return ret;
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err_out_unlock:
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rcu_read_unlock();
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err_out_kobj_put:
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kobject_put(&policy->kobj);
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wait_for_completion(&policy->kobj_unregister);
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@ -854,6 +904,8 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
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unsigned int j, cpu = dev->id;
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int ret = -ENOMEM;
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struct cpufreq_policy *policy;
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struct cpufreq_driver *driver;
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int (*init)(struct cpufreq_policy *policy);
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unsigned long flags;
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#ifdef CONFIG_HOTPLUG_CPU
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struct cpufreq_governor *gov;
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@ -888,10 +940,15 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
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#endif
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#endif
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if (!try_module_get(cpufreq_driver->owner)) {
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rcu_read_lock();
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driver = rcu_dereference(cpufreq_driver);
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if (!try_module_get(driver->owner)) {
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rcu_read_unlock();
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ret = -EINVAL;
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goto module_out;
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}
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init = driver->init;
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rcu_read_unlock();
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policy = kzalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
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if (!policy)
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@ -916,7 +973,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
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/* call driver. From then on the cpufreq must be able
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* to accept all calls to ->verify and ->setpolicy for this CPU
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*/
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ret = cpufreq_driver->init(policy);
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ret = init(policy);
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if (ret) {
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pr_debug("initialization failed\n");
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goto err_set_policy_cpu;
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@ -951,7 +1008,9 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
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goto err_out_unregister;
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kobject_uevent(&policy->kobj, KOBJ_ADD);
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module_put(cpufreq_driver->owner);
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rcu_read_lock();
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module_put(rcu_dereference(cpufreq_driver)->owner);
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rcu_read_unlock();
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pr_debug("initialization complete\n");
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return 0;
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@ -973,7 +1032,9 @@ err_free_cpumask:
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err_free_policy:
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kfree(policy);
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nomem_out:
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module_put(cpufreq_driver->owner);
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rcu_read_lock();
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module_put(rcu_dereference(cpufreq_driver)->owner);
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rcu_read_unlock();
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module_out:
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return ret;
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}
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@ -1007,9 +1068,12 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
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unsigned int cpu = dev->id, ret, cpus;
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unsigned long flags;
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struct cpufreq_policy *data;
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struct cpufreq_driver *driver;
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struct kobject *kobj;
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struct completion *cmp;
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struct device *cpu_dev;
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bool has_target;
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int (*exit)(struct cpufreq_policy *policy);
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pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
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@ -1025,14 +1089,19 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
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return -EINVAL;
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}
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if (cpufreq_driver->target)
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rcu_read_lock();
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driver = rcu_dereference(cpufreq_driver);
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has_target = driver->target ? true : false;
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exit = driver->exit;
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if (has_target)
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__cpufreq_governor(data, CPUFREQ_GOV_STOP);
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#ifdef CONFIG_HOTPLUG_CPU
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if (!cpufreq_driver->setpolicy)
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if (!driver->setpolicy)
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strncpy(per_cpu(cpufreq_cpu_governor, cpu),
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data->governor->name, CPUFREQ_NAME_LEN);
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#endif
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rcu_read_unlock();
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WARN_ON(lock_policy_rwsem_write(cpu));
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cpus = cpumask_weight(data->cpus);
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@ -1091,13 +1160,13 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
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wait_for_completion(cmp);
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pr_debug("wait complete\n");
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if (cpufreq_driver->exit)
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cpufreq_driver->exit(data);
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if (exit)
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exit(data);
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free_cpumask_var(data->related_cpus);
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free_cpumask_var(data->cpus);
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kfree(data);
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} else if (cpufreq_driver->target) {
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} else if (has_target) {
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__cpufreq_governor(data, CPUFREQ_GOV_START);
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__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
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}
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@ -1171,10 +1240,18 @@ static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq,
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unsigned int cpufreq_quick_get(unsigned int cpu)
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{
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struct cpufreq_policy *policy;
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struct cpufreq_driver *driver;
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unsigned int (*get)(unsigned int cpu);
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unsigned int ret_freq = 0;
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if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get)
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return cpufreq_driver->get(cpu);
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rcu_read_lock();
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driver = rcu_dereference(cpufreq_driver);
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if (driver && driver->setpolicy && driver->get) {
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get = driver->get;
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rcu_read_unlock();
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return get(cpu);
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}
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rcu_read_unlock();
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policy = cpufreq_cpu_get(cpu);
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if (policy) {
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@ -1210,15 +1287,26 @@ EXPORT_SYMBOL(cpufreq_quick_get_max);
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static unsigned int __cpufreq_get(unsigned int cpu)
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{
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struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
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struct cpufreq_driver *driver;
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unsigned int (*get)(unsigned int cpu);
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unsigned int ret_freq = 0;
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u8 flags;
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if (!cpufreq_driver->get)
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rcu_read_lock();
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driver = rcu_dereference(cpufreq_driver);
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if (!driver->get) {
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rcu_read_unlock();
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return ret_freq;
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}
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flags = driver->flags;
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get = driver->get;
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rcu_read_unlock();
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ret_freq = cpufreq_driver->get(cpu);
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ret_freq = get(cpu);
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if (ret_freq && policy->cur &&
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!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
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!(flags & CPUFREQ_CONST_LOOPS)) {
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/* verify no discrepancy between actual and
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saved value exists */
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if (unlikely(ret_freq != policy->cur)) {
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@ -1274,6 +1362,7 @@ static struct subsys_interface cpufreq_interface = {
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*/
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static int cpufreq_bp_suspend(void)
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{
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int (*suspend)(struct cpufreq_policy *policy);
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int ret = 0;
|
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int cpu = smp_processor_id();
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@ -1286,8 +1375,11 @@ static int cpufreq_bp_suspend(void)
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if (!cpu_policy)
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return 0;
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if (cpufreq_driver->suspend) {
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ret = cpufreq_driver->suspend(cpu_policy);
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rcu_read_lock();
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suspend = rcu_dereference(cpufreq_driver)->suspend;
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rcu_read_unlock();
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if (suspend) {
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ret = suspend(cpu_policy);
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if (ret)
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printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
|
||||
"step on CPU %u\n", cpu_policy->cpu);
|
||||
@ -1313,6 +1405,7 @@ static int cpufreq_bp_suspend(void)
|
||||
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;
|
||||
@ -1324,8 +1417,12 @@ static void cpufreq_bp_resume(void)
|
||||
if (!cpu_policy)
|
||||
return;
|
||||
|
||||
if (cpufreq_driver->resume) {
|
||||
ret = cpufreq_driver->resume(cpu_policy);
|
||||
rcu_read_lock();
|
||||
resume = rcu_dereference(cpufreq_driver)->resume;
|
||||
rcu_read_unlock();
|
||||
|
||||
if (resume) {
|
||||
ret = resume(cpu_policy);
|
||||
if (ret) {
|
||||
printk(KERN_ERR "cpufreq: resume failed in ->resume "
|
||||
"step on CPU %u\n", cpu_policy->cpu);
|
||||
@ -1352,10 +1449,14 @@ static struct syscore_ops cpufreq_syscore_ops = {
|
||||
*/
|
||||
const char *cpufreq_get_current_driver(void)
|
||||
{
|
||||
if (cpufreq_driver)
|
||||
return cpufreq_driver->name;
|
||||
|
||||
return NULL;
|
||||
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;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(cpufreq_get_current_driver);
|
||||
|
||||
@ -1449,6 +1550,9 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
|
||||
{
|
||||
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;
|
||||
@ -1465,8 +1569,11 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
|
||||
if (target_freq == policy->cur)
|
||||
return 0;
|
||||
|
||||
if (cpufreq_driver->target)
|
||||
retval = cpufreq_driver->target(policy, target_freq, relation);
|
||||
rcu_read_lock();
|
||||
target = rcu_dereference(cpufreq_driver)->target;
|
||||
rcu_read_unlock();
|
||||
if (target)
|
||||
retval = target(policy, target_freq, relation);
|
||||
|
||||
return retval;
|
||||
}
|
||||
@ -1499,18 +1606,24 @@ EXPORT_SYMBOL_GPL(cpufreq_driver_target);
|
||||
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;
|
||||
|
||||
if (!cpufreq_driver->getavg)
|
||||
rcu_read_lock();
|
||||
getavg = rcu_dereference(cpufreq_driver)->getavg;
|
||||
rcu_read_unlock();
|
||||
|
||||
if (!getavg)
|
||||
return 0;
|
||||
|
||||
policy = cpufreq_cpu_get(policy->cpu);
|
||||
if (!policy)
|
||||
return -EINVAL;
|
||||
|
||||
ret = cpufreq_driver->getavg(policy, cpu);
|
||||
ret = getavg(policy, cpu);
|
||||
|
||||
cpufreq_cpu_put(policy);
|
||||
return ret;
|
||||
@ -1668,6 +1781,9 @@ static int __cpufreq_set_policy(struct cpufreq_policy *data,
|
||||
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);
|
||||
@ -1681,7 +1797,13 @@ static int __cpufreq_set_policy(struct cpufreq_policy *data,
|
||||
}
|
||||
|
||||
/* verify the cpu speed can be set within this limit */
|
||||
ret = cpufreq_driver->verify(policy);
|
||||
rcu_read_lock();
|
||||
driver = rcu_dereference(cpufreq_driver);
|
||||
verify = driver->verify;
|
||||
setpolicy = driver->setpolicy;
|
||||
rcu_read_unlock();
|
||||
|
||||
ret = verify(policy);
|
||||
if (ret)
|
||||
goto error_out;
|
||||
|
||||
@ -1695,7 +1817,7 @@ 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 = verify(policy);
|
||||
if (ret)
|
||||
goto error_out;
|
||||
|
||||
@ -1709,10 +1831,10 @@ 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 (setpolicy) {
|
||||
data->policy = policy->policy;
|
||||
pr_debug("setting range\n");
|
||||
ret = cpufreq_driver->setpolicy(policy);
|
||||
ret = setpolicy(policy);
|
||||
} else {
|
||||
if (policy->governor != data->governor) {
|
||||
/* save old, working values */
|
||||
@ -1772,6 +1894,11 @@ int cpufreq_update_policy(unsigned int cpu)
|
||||
{
|
||||
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) {
|
||||
@ -1793,13 +1920,18 @@ 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);
|
||||
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 (!data->cur) {
|
||||
pr_debug("Driver did not initialize current freq");
|
||||
data->cur = policy.cur;
|
||||
} else {
|
||||
if (data->cur != policy.cur && cpufreq_driver->target)
|
||||
if (data->cur != policy.cur && target)
|
||||
cpufreq_out_of_sync(cpu, data->cur,
|
||||
policy.cur);
|
||||
}
|
||||
@ -1878,18 +2010,19 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
|
||||
driver_data->flags |= CPUFREQ_CONST_LOOPS;
|
||||
|
||||
write_lock_irqsave(&cpufreq_driver_lock, flags);
|
||||
if (cpufreq_driver) {
|
||||
if (rcu_access_pointer(cpufreq_driver)) {
|
||||
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
|
||||
return -EBUSY;
|
||||
}
|
||||
cpufreq_driver = driver_data;
|
||||
rcu_assign_pointer(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 (!(cpufreq_driver->flags & CPUFREQ_STICKY)) {
|
||||
if (!(driver_data->flags & CPUFREQ_STICKY)) {
|
||||
int i;
|
||||
ret = -ENODEV;
|
||||
|
||||
@ -1916,8 +2049,9 @@ err_if_unreg:
|
||||
subsys_interface_unregister(&cpufreq_interface);
|
||||
err_null_driver:
|
||||
write_lock_irqsave(&cpufreq_driver_lock, flags);
|
||||
cpufreq_driver = NULL;
|
||||
rcu_assign_pointer(cpufreq_driver, NULL);
|
||||
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
|
||||
synchronize_rcu();
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(cpufreq_register_driver);
|
||||
@ -1934,9 +2068,15 @@ EXPORT_SYMBOL_GPL(cpufreq_register_driver);
|
||||
int cpufreq_unregister_driver(struct cpufreq_driver *driver)
|
||||
{
|
||||
unsigned long flags;
|
||||
struct cpufreq_driver *old_driver;
|
||||
|
||||
if (!cpufreq_driver || (driver != cpufreq_driver))
|
||||
rcu_read_lock();
|
||||
old_driver = rcu_access_pointer(cpufreq_driver);
|
||||
if (!old_driver || (driver != old_driver)) {
|
||||
rcu_read_unlock();
|
||||
return -EINVAL;
|
||||
}
|
||||
rcu_read_unlock();
|
||||
|
||||
pr_debug("unregistering driver %s\n", driver->name);
|
||||
|
||||
@ -1944,8 +2084,9 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
|
||||
unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
|
||||
|
||||
write_lock_irqsave(&cpufreq_driver_lock, flags);
|
||||
cpufreq_driver = NULL;
|
||||
rcu_assign_pointer(cpufreq_driver, NULL);
|
||||
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
|
||||
synchronize_rcu();
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user