diff options
Diffstat (limited to 'drivers/cpufreq/cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 258 |
1 files changed, 180 insertions, 78 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index a45cc89..f52facc 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -41,8 +41,67 @@ static struct cpufreq_driver *cpufreq_driver; static struct cpufreq_policy *cpufreq_cpu_data[NR_CPUS]; static DEFINE_SPINLOCK(cpufreq_driver_lock); +/* + * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure + * all cpufreq/hotplug/workqueue/etc related lock issues. + * + * The rules for this semaphore: + * - Any routine that wants to read from the policy structure will + * do a down_read on this semaphore. + * - Any routine that will write to the policy structure and/or may take away + * the policy altogether (eg. CPU hotplug), will hold this lock in write + * mode before doing so. + * + * Additional rules: + * - All holders of the lock should check to make sure that the CPU they + * are concerned with are online after they get the lock. + * - Governor routines that can be called in cpufreq hotplug path should not + * take this sem as top level hotplug notifier handler takes this. + */ +static DEFINE_PER_CPU(int, policy_cpu); +static DEFINE_PER_CPU(struct rw_semaphore, cpu_policy_rwsem); + +#define lock_policy_rwsem(mode, cpu) \ +int lock_policy_rwsem_##mode \ +(int cpu) \ +{ \ + int policy_cpu = per_cpu(policy_cpu, cpu); \ + BUG_ON(policy_cpu == -1); \ + down_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu)); \ + if (unlikely(!cpu_online(cpu))) { \ + up_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu)); \ + return -1; \ + } \ + \ + return 0; \ +} + +lock_policy_rwsem(read, cpu); +EXPORT_SYMBOL_GPL(lock_policy_rwsem_read); + +lock_policy_rwsem(write, cpu); +EXPORT_SYMBOL_GPL(lock_policy_rwsem_write); + +void unlock_policy_rwsem_read(int cpu) +{ + int policy_cpu = per_cpu(policy_cpu, cpu); + BUG_ON(policy_cpu == -1); + up_read(&per_cpu(cpu_policy_rwsem, policy_cpu)); +} +EXPORT_SYMBOL_GPL(unlock_policy_rwsem_read); + +void unlock_policy_rwsem_write(int cpu) +{ + int policy_cpu = per_cpu(policy_cpu, cpu); + BUG_ON(policy_cpu == -1); + up_write(&per_cpu(cpu_policy_rwsem, policy_cpu)); +} +EXPORT_SYMBOL_GPL(unlock_policy_rwsem_write); + + /* internal prototypes */ static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event); +static unsigned int __cpufreq_get(unsigned int cpu); static void handle_update(struct work_struct *work); /** @@ -415,12 +474,8 @@ static ssize_t store_##file_name \ if (ret != 1) \ return -EINVAL; \ \ - lock_cpu_hotplug(); \ - mutex_lock(&policy->lock); \ ret = __cpufreq_set_policy(policy, &new_policy); \ policy->user_policy.object = policy->object; \ - mutex_unlock(&policy->lock); \ - unlock_cpu_hotplug(); \ \ return ret ? ret : count; \ } @@ -434,7 +489,7 @@ store_one(scaling_max_freq,max); static ssize_t show_cpuinfo_cur_freq (struct cpufreq_policy * policy, char *buf) { - unsigned int cur_freq = cpufreq_get(policy->cpu); + unsigned int cur_freq = __cpufreq_get(policy->cpu); if (!cur_freq) return sprintf(buf, "<unknown>"); return sprintf(buf, "%u\n", cur_freq); @@ -479,18 +534,12 @@ static ssize_t store_scaling_governor (struct cpufreq_policy * policy, &new_policy.governor)) return -EINVAL; - lock_cpu_hotplug(); - /* Do not use cpufreq_set_policy here or the user_policy.max will be wrongly overridden */ - mutex_lock(&policy->lock); ret = __cpufreq_set_policy(policy, &new_policy); policy->user_policy.policy = policy->policy; policy->user_policy.governor = policy->governor; - mutex_unlock(&policy->lock); - - unlock_cpu_hotplug(); if (ret) return ret; @@ -595,11 +644,17 @@ static ssize_t show(struct kobject * kobj, struct attribute * attr ,char * buf) policy = cpufreq_cpu_get(policy->cpu); if (!policy) return -EINVAL; + + if (lock_policy_rwsem_read(policy->cpu) < 0) + return -EINVAL; + if (fattr->show) ret = fattr->show(policy, buf); else ret = -EIO; + unlock_policy_rwsem_read(policy->cpu); + cpufreq_cpu_put(policy); return ret; } @@ -613,11 +668,17 @@ static ssize_t store(struct kobject * kobj, struct attribute * attr, policy = cpufreq_cpu_get(policy->cpu); if (!policy) return -EINVAL; + + if (lock_policy_rwsem_write(policy->cpu) < 0) + return -EINVAL; + if (fattr->store) ret = fattr->store(policy, buf, count); else ret = -EIO; + unlock_policy_rwsem_write(policy->cpu); + cpufreq_cpu_put(policy); return ret; } @@ -691,8 +752,10 @@ static int cpufreq_add_dev (struct sys_device * sys_dev) policy->cpu = cpu; policy->cpus = cpumask_of_cpu(cpu); - mutex_init(&policy->lock); - mutex_lock(&policy->lock); + /* Initially set CPU itself as the policy_cpu */ + per_cpu(policy_cpu, cpu) = cpu; + lock_policy_rwsem_write(cpu); + init_completion(&policy->kobj_unregister); INIT_WORK(&policy->update, handle_update); @@ -702,7 +765,7 @@ static int cpufreq_add_dev (struct sys_device * sys_dev) ret = cpufreq_driver->init(policy); if (ret) { dprintk("initialization failed\n"); - mutex_unlock(&policy->lock); + unlock_policy_rwsem_write(cpu); goto err_out; } @@ -716,6 +779,14 @@ static int cpufreq_add_dev (struct sys_device * sys_dev) */ managed_policy = cpufreq_cpu_get(j); if (unlikely(managed_policy)) { + + /* Set proper policy_cpu */ + unlock_policy_rwsem_write(cpu); + per_cpu(policy_cpu, cpu) = managed_policy->cpu; + + if (lock_policy_rwsem_write(cpu) < 0) + goto err_out_driver_exit; + spin_lock_irqsave(&cpufreq_driver_lock, flags); managed_policy->cpus = policy->cpus; cpufreq_cpu_data[cpu] = managed_policy; @@ -726,13 +797,13 @@ static int cpufreq_add_dev (struct sys_device * sys_dev) &managed_policy->kobj, "cpufreq"); if (ret) { - mutex_unlock(&policy->lock); + unlock_policy_rwsem_write(cpu); goto err_out_driver_exit; } cpufreq_debug_enable_ratelimit(); - mutex_unlock(&policy->lock); ret = 0; + unlock_policy_rwsem_write(cpu); goto err_out_driver_exit; /* call driver->exit() */ } } @@ -746,7 +817,7 @@ static int cpufreq_add_dev (struct sys_device * sys_dev) ret = kobject_register(&policy->kobj); if (ret) { - mutex_unlock(&policy->lock); + unlock_policy_rwsem_write(cpu); goto err_out_driver_exit; } /* set up files for this cpu device */ @@ -761,8 +832,10 @@ static int cpufreq_add_dev (struct sys_device * sys_dev) sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr); spin_lock_irqsave(&cpufreq_driver_lock, flags); - for_each_cpu_mask(j, policy->cpus) + for_each_cpu_mask(j, policy->cpus) { cpufreq_cpu_data[j] = policy; + per_cpu(policy_cpu, j) = policy->cpu; + } spin_unlock_irqrestore(&cpufreq_driver_lock, flags); /* symlink affected CPUs */ @@ -778,14 +851,14 @@ static int cpufreq_add_dev (struct sys_device * sys_dev) ret = sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj, "cpufreq"); if (ret) { - mutex_unlock(&policy->lock); + unlock_policy_rwsem_write(cpu); goto err_out_unregister; } } policy->governor = NULL; /* to assure that the starting sequence is * run in cpufreq_set_policy */ - mutex_unlock(&policy->lock); + unlock_policy_rwsem_write(cpu); /* set default policy */ ret = cpufreq_set_policy(&new_policy); @@ -826,11 +899,13 @@ module_out: /** - * cpufreq_remove_dev - remove a CPU device + * __cpufreq_remove_dev - remove a CPU device * * Removes the cpufreq interface for a CPU device. + * Caller should already have policy_rwsem in write mode for this CPU. + * This routine frees the rwsem before returning. */ -static int cpufreq_remove_dev (struct sys_device * sys_dev) +static int __cpufreq_remove_dev (struct sys_device * sys_dev) { unsigned int cpu = sys_dev->id; unsigned long flags; @@ -849,6 +924,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev) if (!data) { spin_unlock_irqrestore(&cpufreq_driver_lock, flags); cpufreq_debug_enable_ratelimit(); + unlock_policy_rwsem_write(cpu); return -EINVAL; } cpufreq_cpu_data[cpu] = NULL; @@ -865,6 +941,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev) sysfs_remove_link(&sys_dev->kobj, "cpufreq"); cpufreq_cpu_put(data); cpufreq_debug_enable_ratelimit(); + unlock_policy_rwsem_write(cpu); return 0; } #endif @@ -873,6 +950,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev) if (!kobject_get(&data->kobj)) { spin_unlock_irqrestore(&cpufreq_driver_lock, flags); cpufreq_debug_enable_ratelimit(); + unlock_policy_rwsem_write(cpu); return -EFAULT; } @@ -906,10 +984,10 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev) spin_unlock_irqrestore(&cpufreq_driver_lock, flags); #endif - mutex_lock(&data->lock); if (cpufreq_driver->target) __cpufreq_governor(data, CPUFREQ_GOV_STOP); - mutex_unlock(&data->lock); + + unlock_policy_rwsem_write(cpu); kobject_unregister(&data->kobj); @@ -933,6 +1011,18 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev) } +static int cpufreq_remove_dev (struct sys_device * sys_dev) +{ + unsigned int cpu = sys_dev->id; + int retval; + if (unlikely(lock_policy_rwsem_write(cpu))) + BUG(); + + retval = __cpufreq_remove_dev(sys_dev); + return retval; +} + + static void handle_update(struct work_struct *work) { struct cpufreq_policy *policy = @@ -980,9 +1070,12 @@ unsigned int cpufreq_quick_get(unsigned int cpu) unsigned int ret_freq = 0; if (policy) { - mutex_lock(&policy->lock); + if (unlikely(lock_policy_rwsem_read(cpu))) + return ret_freq; + ret_freq = policy->cur; - mutex_unlock(&policy->lock); + + unlock_policy_rwsem_read(cpu); cpufreq_cpu_put(policy); } @@ -991,24 +1084,13 @@ unsigned int cpufreq_quick_get(unsigned int cpu) EXPORT_SYMBOL(cpufreq_quick_get); -/** - * cpufreq_get - get the current CPU frequency (in kHz) - * @cpu: CPU number - * - * Get the CPU current (static) CPU frequency - */ -unsigned int cpufreq_get(unsigned int cpu) +static unsigned int __cpufreq_get(unsigned int cpu) { - struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); + struct cpufreq_policy *policy = cpufreq_cpu_data[cpu]; unsigned int ret_freq = 0; - if (!policy) - return 0; - if (!cpufreq_driver->get) - goto out; - - mutex_lock(&policy->lock); + return (ret_freq); ret_freq = cpufreq_driver->get(cpu); @@ -1022,11 +1104,33 @@ unsigned int cpufreq_get(unsigned int cpu) } } - mutex_unlock(&policy->lock); + return (ret_freq); +} -out: - cpufreq_cpu_put(policy); +/** + * cpufreq_get - get the current CPU frequency (in kHz) + * @cpu: CPU number + * + * Get the CPU current (static) CPU frequency + */ +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 (unlikely(lock_policy_rwsem_read(cpu))) + goto out_policy; + + ret_freq = __cpufreq_get(cpu); + unlock_policy_rwsem_read(cpu); + +out_policy: + cpufreq_cpu_put(policy); +out: return (ret_freq); } EXPORT_SYMBOL(cpufreq_get); @@ -1278,7 +1382,6 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier); *********************************************************************/ -/* Must be called with lock_cpu_hotplug held */ int __cpufreq_driver_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) @@ -1304,20 +1407,19 @@ int cpufreq_driver_target(struct cpufreq_policy *policy, if (!policy) return -EINVAL; - lock_cpu_hotplug(); - mutex_lock(&policy->lock); + if (unlikely(lock_policy_rwsem_write(policy->cpu))) + return -EINVAL; ret = __cpufreq_driver_target(policy, target_freq, relation); - mutex_unlock(&policy->lock); - unlock_cpu_hotplug(); + unlock_policy_rwsem_write(policy->cpu); cpufreq_cpu_put(policy); return ret; } EXPORT_SYMBOL_GPL(cpufreq_driver_target); -int cpufreq_driver_getavg(struct cpufreq_policy *policy) +int __cpufreq_driver_getavg(struct cpufreq_policy *policy) { int ret = 0; @@ -1325,20 +1427,15 @@ int cpufreq_driver_getavg(struct cpufreq_policy *policy) if (!policy) return -EINVAL; - mutex_lock(&policy->lock); - if (cpu_online(policy->cpu) && cpufreq_driver->getavg) ret = cpufreq_driver->getavg(policy->cpu); - mutex_unlock(&policy->lock); - cpufreq_cpu_put(policy); return ret; } -EXPORT_SYMBOL_GPL(cpufreq_driver_getavg); +EXPORT_SYMBOL_GPL(__cpufreq_driver_getavg); /* - * Locking: Must be called with the lock_cpu_hotplug() lock held * when "event" is CPUFREQ_GOV_LIMITS */ @@ -1420,9 +1517,7 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu) if (!cpu_policy) return -EINVAL; - mutex_lock(&cpu_policy->lock); memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy)); - mutex_unlock(&cpu_policy->lock); cpufreq_cpu_put(cpu_policy); return 0; @@ -1433,7 +1528,6 @@ EXPORT_SYMBOL(cpufreq_get_policy); /* * data : current policy. * policy : policy to be set. - * Locking: Must be called with the lock_cpu_hotplug() lock held */ static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_policy *policy) @@ -1539,10 +1633,9 @@ int cpufreq_set_policy(struct cpufreq_policy *policy) if (!data) return -EINVAL; - lock_cpu_hotplug(); + if (unlikely(lock_policy_rwsem_write(policy->cpu))) + return -EINVAL; - /* lock this CPU */ - mutex_lock(&data->lock); ret = __cpufreq_set_policy(data, policy); data->user_policy.min = data->min; @@ -1550,9 +1643,8 @@ int cpufreq_set_policy(struct cpufreq_policy *policy) data->user_policy.policy = data->policy; data->user_policy.governor = data->governor; - mutex_unlock(&data->lock); + unlock_policy_rwsem_write(policy->cpu); - unlock_cpu_hotplug(); cpufreq_cpu_put(data); return ret; @@ -1576,8 +1668,8 @@ int cpufreq_update_policy(unsigned int cpu) if (!data) return -ENODEV; - lock_cpu_hotplug(); - mutex_lock(&data->lock); + if (unlikely(lock_policy_rwsem_write(cpu))) + return -EINVAL; dprintk("updating policy for CPU %u\n", cpu); memcpy(&policy, data, sizeof(struct cpufreq_policy)); @@ -1602,8 +1694,8 @@ int cpufreq_update_policy(unsigned int cpu) ret = __cpufreq_set_policy(data, &policy); - mutex_unlock(&data->lock); - unlock_cpu_hotplug(); + unlock_policy_rwsem_write(cpu); + cpufreq_cpu_put(data); return ret; } @@ -1613,31 +1705,28 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { unsigned int cpu = (unsigned long)hcpu; - struct cpufreq_policy *policy; struct sys_device *sys_dev; + struct cpufreq_policy *policy; sys_dev = get_cpu_sysdev(cpu); - if (sys_dev) { switch (action) { case CPU_ONLINE: cpufreq_add_dev(sys_dev); break; case CPU_DOWN_PREPARE: - /* - * We attempt to put this cpu in lowest frequency - * possible before going down. This will permit - * hardware-managed P-State to switch other related - * threads to min or higher speeds if possible. - */ + if (unlikely(lock_policy_rwsem_write(cpu))) + BUG(); + policy = cpufreq_cpu_data[cpu]; if (policy) { - cpufreq_driver_target(policy, policy->min, + __cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_H); } + __cpufreq_remove_dev(sys_dev); break; - case CPU_DEAD: - cpufreq_remove_dev(sys_dev); + case CPU_DOWN_FAILED: + cpufreq_add_dev(sys_dev); break; } } @@ -1751,3 +1840,16 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver) return 0; } EXPORT_SYMBOL_GPL(cpufreq_unregister_driver); + +static int __init cpufreq_core_init(void) +{ + int cpu; + + for_each_possible_cpu(cpu) { + per_cpu(policy_cpu, cpu) = -1; + init_rwsem(&per_cpu(cpu_policy_rwsem, cpu)); + } + return 0; +} + +core_initcall(cpufreq_core_init); |