diff options
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 135 |
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; } |