cpufreq: Convert the cpufreq_driver_lock to a rwlock
This eliminates the contention I am seeing in __cpufreq_cpu_get. It also nicely stages the lock to be replaced by the rcu. 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
07961ac7c0
commit
0d1857a1b9
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@ -45,7 +45,7 @@ static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
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/* This one keeps track of the previously set governor of a removed CPU */
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static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
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#endif
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static DEFINE_SPINLOCK(cpufreq_driver_lock);
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static DEFINE_RWLOCK(cpufreq_driver_lock);
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/*
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* cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
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@ -137,7 +137,7 @@ static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
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goto err_out;
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/* get the cpufreq driver */
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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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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@ -155,13 +155,13 @@ static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
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if (!sysfs && !kobject_get(&data->kobj))
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goto err_out_put_module;
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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read_unlock_irqrestore(&cpufreq_driver_lock, flags);
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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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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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read_unlock_irqrestore(&cpufreq_driver_lock, flags);
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err_out:
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return NULL;
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}
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@ -266,9 +266,9 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
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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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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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read_lock_irqsave(&cpufreq_driver_lock, flags);
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policy = per_cpu(cpufreq_cpu_data, freqs->cpu);
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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read_unlock_irqrestore(&cpufreq_driver_lock, flags);
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switch (state) {
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@ -765,12 +765,12 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
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goto err_out_kobj_put;
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}
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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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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per_cpu(cpufreq_cpu_data, j) = policy;
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per_cpu(cpufreq_policy_cpu, j) = policy->cpu;
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}
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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ret = cpufreq_add_dev_symlink(cpu, policy);
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if (ret)
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@ -813,12 +813,12 @@ static int cpufreq_add_policy_cpu(unsigned int cpu, unsigned int sibling,
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lock_policy_rwsem_write(sibling);
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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write_lock_irqsave(&cpufreq_driver_lock, flags);
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cpumask_set_cpu(cpu, policy->cpus);
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per_cpu(cpufreq_policy_cpu, cpu) = policy->cpu;
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per_cpu(cpufreq_cpu_data, cpu) = policy;
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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unlock_policy_rwsem_write(sibling);
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@ -871,15 +871,15 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
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#ifdef CONFIG_HOTPLUG_CPU
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/* Check if this cpu was hot-unplugged earlier and has siblings */
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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read_lock_irqsave(&cpufreq_driver_lock, flags);
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for_each_online_cpu(sibling) {
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struct cpufreq_policy *cp = per_cpu(cpufreq_cpu_data, sibling);
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if (cp && cpumask_test_cpu(cpu, cp->related_cpus)) {
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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read_unlock_irqrestore(&cpufreq_driver_lock, flags);
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return cpufreq_add_policy_cpu(cpu, sibling, dev);
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}
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}
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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read_unlock_irqrestore(&cpufreq_driver_lock, flags);
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#endif
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#endif
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@ -952,10 +952,10 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
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return 0;
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err_out_unregister:
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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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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per_cpu(cpufreq_cpu_data, j) = NULL;
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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kobject_put(&policy->kobj);
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wait_for_completion(&policy->kobj_unregister);
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@ -1008,12 +1008,12 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
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pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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write_lock_irqsave(&cpufreq_driver_lock, flags);
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data = per_cpu(cpufreq_cpu_data, cpu);
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per_cpu(cpufreq_cpu_data, cpu) = NULL;
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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if (!data) {
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pr_debug("%s: No cpu_data found\n", __func__);
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@ -1047,9 +1047,9 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
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WARN_ON(lock_policy_rwsem_write(cpu));
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cpumask_set_cpu(cpu, data->cpus);
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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write_lock_irqsave(&cpufreq_driver_lock, flags);
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per_cpu(cpufreq_cpu_data, cpu) = data;
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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unlock_policy_rwsem_write(cpu);
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@ -1848,13 +1848,13 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
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if (driver_data->setpolicy)
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driver_data->flags |= CPUFREQ_CONST_LOOPS;
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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write_lock_irqsave(&cpufreq_driver_lock, flags);
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if (cpufreq_driver) {
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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return -EBUSY;
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}
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cpufreq_driver = driver_data;
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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ret = subsys_interface_register(&cpufreq_interface);
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if (ret)
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@ -1886,9 +1886,9 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
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err_if_unreg:
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subsys_interface_unregister(&cpufreq_interface);
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err_null_driver:
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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write_lock_irqsave(&cpufreq_driver_lock, flags);
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cpufreq_driver = NULL;
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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return ret;
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}
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EXPORT_SYMBOL_GPL(cpufreq_register_driver);
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@ -1914,9 +1914,9 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
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subsys_interface_unregister(&cpufreq_interface);
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unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
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spin_lock_irqsave(&cpufreq_driver_lock, flags);
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write_lock_irqsave(&cpufreq_driver_lock, flags);
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cpufreq_driver = NULL;
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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write_unlock_irqrestore(&cpufreq_driver_lock, flags);
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return 0;
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}
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