cpufreq: Simplify __cpufreq_remove_dev()
__cpufreq_remove_dev() is called on multiple occasions: cpufreq_driver unregister and cpu removals. Current implementation of this routine is overly complex without much need. If the cpu to be removed is the policy->cpu, we remove the policy first and add all other cpus again from policy->cpus and then finally call __cpufreq_remove_dev() again to remove the cpu to be deleted. Haahhhh.. There exist a simple solution to removal of a cpu: - Simply use the old policy structure - update its fields like: policy->cpu, etc. - notify any users of cpufreq, which depend on changing policy->cpu Hence this patch, which tries to implement the above theory. It is tested well by myself on ARM big.LITTLE TC2 SoC, which has 5 cores (2 A15 and 3 A7). Both A15's share same struct policy and all A7's share same policy structure. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Tested-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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@ -1036,6 +1036,25 @@ module_out:
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return ret;
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}
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static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
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{
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int j;
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policy->last_cpu = policy->cpu;
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policy->cpu = cpu;
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for_each_cpu(j, policy->cpus) {
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if (!cpu_online(j))
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continue;
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per_cpu(cpufreq_policy_cpu, j) = cpu;
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}
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#ifdef CONFIG_CPU_FREQ_TABLE
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cpufreq_frequency_table_update_policy_cpu(policy);
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#endif
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blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
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CPUFREQ_UPDATE_POLICY_CPU, policy);
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}
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/**
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* __cpufreq_remove_dev - remove a CPU device
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@ -1046,132 +1065,92 @@ module_out:
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*/
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static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
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{
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unsigned int cpu = dev->id;
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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 kobject *kobj;
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struct completion *cmp;
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#ifdef CONFIG_SMP
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struct device *cpu_dev;
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unsigned int j;
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#endif
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pr_debug("unregistering CPU %u\n", cpu);
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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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data = per_cpu(cpufreq_cpu_data, cpu);
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if (!data) {
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pr_debug("%s: No cpu_data found\n", __func__);
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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unlock_policy_rwsem_write(cpu);
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return -EINVAL;
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}
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per_cpu(cpufreq_cpu_data, cpu) = NULL;
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#ifdef CONFIG_SMP
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/* if this isn't the CPU which is the parent of the kobj, we
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* only need to unlink, put and exit
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*/
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if (unlikely(cpu != data->cpu)) {
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pr_debug("removing link\n");
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if (cpufreq_driver->target)
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__cpufreq_governor(data, CPUFREQ_GOV_STOP);
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cpumask_clear_cpu(cpu, data->cpus);
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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__cpufreq_governor(data, CPUFREQ_GOV_START);
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__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
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kobj = &dev->kobj;
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cpufreq_cpu_put(data);
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unlock_policy_rwsem_write(cpu);
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sysfs_remove_link(kobj, "cpufreq");
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return 0;
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}
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#endif
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#ifdef CONFIG_SMP
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#ifdef CONFIG_HOTPLUG_CPU
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strncpy(per_cpu(cpufreq_cpu_governor, cpu), data->governor->name,
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CPUFREQ_NAME_LEN);
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#endif
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/* if we have other CPUs still registered, we need to unlink them,
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* or else wait_for_completion below will lock up. Clean the
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* per_cpu(cpufreq_cpu_data) while holding the lock, and remove
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* the sysfs links afterwards.
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*/
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if (unlikely(cpumask_weight(data->cpus) > 1)) {
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for_each_cpu(j, data->cpus) {
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if (j == cpu)
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continue;
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per_cpu(cpufreq_cpu_data, j) = NULL;
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}
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}
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per_cpu(cpufreq_cpu_data, cpu) = NULL;
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cpus = cpumask_weight(data->cpus);
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cpumask_clear_cpu(cpu, data->cpus);
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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if (unlikely(cpumask_weight(data->cpus) > 1)) {
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for_each_cpu(j, data->cpus) {
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if (j == cpu)
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continue;
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pr_debug("removing link for cpu %u\n", j);
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#ifdef CONFIG_HOTPLUG_CPU
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strncpy(per_cpu(cpufreq_cpu_governor, j),
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data->governor->name, CPUFREQ_NAME_LEN);
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#endif
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cpu_dev = get_cpu_device(j);
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kobj = &cpu_dev->kobj;
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unlock_policy_rwsem_write(cpu);
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sysfs_remove_link(kobj, "cpufreq");
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lock_policy_rwsem_write(cpu);
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cpufreq_cpu_put(data);
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}
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}
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#else
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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#endif
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if (cpufreq_driver->target)
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__cpufreq_governor(data, CPUFREQ_GOV_STOP);
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kobj = &data->kobj;
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cmp = &data->kobj_unregister;
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unlock_policy_rwsem_write(cpu);
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kobject_put(kobj);
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/* we need to make sure that the underlying kobj is actually
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* not referenced anymore by anybody before we proceed with
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* unloading.
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*/
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pr_debug("waiting for dropping of refcount\n");
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wait_for_completion(cmp);
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pr_debug("wait complete\n");
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lock_policy_rwsem_write(cpu);
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if (cpufreq_driver->exit)
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cpufreq_driver->exit(data);
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unlock_policy_rwsem_write(cpu);
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#ifdef CONFIG_HOTPLUG_CPU
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/* when the CPU which is the parent of the kobj is hotplugged
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* offline, check for siblings, and create cpufreq sysfs interface
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* and symlinks
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*/
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if (unlikely(cpumask_weight(data->cpus) > 1)) {
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if (unlikely((cpu == data->cpu) && (cpus > 1))) {
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/* first sibling now owns the new sysfs dir */
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cpumask_clear_cpu(cpu, data->cpus);
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cpufreq_add_dev(get_cpu_device(cpumask_first(data->cpus)), NULL);
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cpu_dev = get_cpu_device(cpumask_first(data->cpus));
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sysfs_remove_link(&cpu_dev->kobj, "cpufreq");
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ret = kobject_move(&data->kobj, &cpu_dev->kobj);
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if (ret) {
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pr_err("%s: Failed to move kobj: %d", __func__, ret);
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cpumask_set_cpu(cpu, data->cpus);
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ret = sysfs_create_link(&cpu_dev->kobj, &data->kobj,
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"cpufreq");
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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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unlock_policy_rwsem_write(cpu);
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return -EINVAL;
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}
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/* finally remove our own symlink */
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lock_policy_rwsem_write(cpu);
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__cpufreq_remove_dev(dev, sif);
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update_policy_cpu(data, cpu_dev->id);
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pr_debug("%s: policy Kobject moved to cpu: %d from: %d\n",
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__func__, cpu_dev->id, cpu);
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}
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#endif
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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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spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
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pr_debug("%s: removing link, cpu: %d\n", __func__, cpu);
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cpufreq_cpu_put(data);
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unlock_policy_rwsem_write(cpu);
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sysfs_remove_link(&dev->kobj, "cpufreq");
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/* If cpu is last user of policy, free policy */
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if (cpus == 1) {
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lock_policy_rwsem_write(cpu);
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kobj = &data->kobj;
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cmp = &data->kobj_unregister;
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unlock_policy_rwsem_write(cpu);
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kobject_put(kobj);
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/* we need to make sure that the underlying kobj is actually
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* not referenced anymore by anybody before we proceed with
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* unloading.
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*/
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pr_debug("waiting for dropping of refcount\n");
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wait_for_completion(cmp);
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pr_debug("wait complete\n");
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lock_policy_rwsem_write(cpu);
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if (cpufreq_driver->exit)
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cpufreq_driver->exit(data);
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unlock_policy_rwsem_write(cpu);
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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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__cpufreq_governor(data, CPUFREQ_GOV_START);
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__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
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}
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return 0;
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}
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@ -170,11 +170,13 @@ static int freq_table_get_index(struct cpufreq_stats *stat, unsigned int freq)
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static void cpufreq_stats_free_table(unsigned int cpu)
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{
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struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, cpu);
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if (stat) {
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pr_debug("%s: Free stat table\n", __func__);
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kfree(stat->time_in_state);
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kfree(stat);
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per_cpu(cpufreq_stats_table, cpu) = NULL;
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}
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per_cpu(cpufreq_stats_table, cpu) = NULL;
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}
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/* must be called early in the CPU removal sequence (before
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@ -183,8 +185,10 @@ static void cpufreq_stats_free_table(unsigned int cpu)
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static void cpufreq_stats_free_sysfs(unsigned int cpu)
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{
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struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
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if (policy && policy->cpu == cpu)
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if (policy && (cpumask_weight(policy->cpus) == 1)) {
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pr_debug("%s: Free sysfs stat\n", __func__);
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sysfs_remove_group(&policy->kobj, &stats_attr_group);
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}
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if (policy)
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cpufreq_cpu_put(policy);
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}
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return ret;
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}
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static void cpufreq_stats_update_policy_cpu(struct cpufreq_policy *policy)
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{
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struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table,
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policy->last_cpu);
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pr_debug("Updating stats_table for new_cpu %u from last_cpu %u\n",
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policy->cpu, policy->last_cpu);
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per_cpu(cpufreq_stats_table, policy->cpu) = per_cpu(cpufreq_stats_table,
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policy->last_cpu);
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per_cpu(cpufreq_stats_table, policy->last_cpu) = NULL;
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stat->cpu = policy->cpu;
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}
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static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
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unsigned long val, void *data)
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{
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struct cpufreq_policy *policy = data;
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struct cpufreq_frequency_table *table;
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unsigned int cpu = policy->cpu;
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if (val == CPUFREQ_UPDATE_POLICY_CPU) {
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cpufreq_stats_update_policy_cpu(policy);
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return 0;
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}
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if (val != CPUFREQ_NOTIFY)
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return 0;
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table = cpufreq_frequency_get_table(cpu);
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@ -227,6 +227,15 @@ void cpufreq_frequency_table_put_attr(unsigned int cpu)
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}
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EXPORT_SYMBOL_GPL(cpufreq_frequency_table_put_attr);
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void cpufreq_frequency_table_update_policy_cpu(struct cpufreq_policy *policy)
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{
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pr_debug("Updating show_table for new_cpu %u from last_cpu %u\n",
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policy->cpu, policy->last_cpu);
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per_cpu(cpufreq_show_table, policy->cpu) = per_cpu(cpufreq_show_table,
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policy->last_cpu);
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per_cpu(cpufreq_show_table, policy->last_cpu) = NULL;
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}
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struct cpufreq_frequency_table *cpufreq_frequency_get_table(unsigned int cpu)
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{
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return per_cpu(cpufreq_show_table, cpu);
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@ -93,7 +93,9 @@ struct cpufreq_policy {
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cpumask_var_t related_cpus; /* CPUs with any coordination */
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unsigned int shared_type; /* ANY or ALL affected CPUs
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should set cpufreq */
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unsigned int cpu; /* cpu nr of registered CPU */
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unsigned int cpu; /* cpu nr of CPU managing this policy */
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unsigned int last_cpu; /* cpu nr of previous CPU that managed
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* this policy */
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struct cpufreq_cpuinfo cpuinfo;/* see above */
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unsigned int min; /* in kHz */
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struct completion kobj_unregister;
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};
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#define CPUFREQ_ADJUST (0)
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#define CPUFREQ_INCOMPATIBLE (1)
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#define CPUFREQ_NOTIFY (2)
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#define CPUFREQ_START (3)
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#define CPUFREQ_ADJUST (0)
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#define CPUFREQ_INCOMPATIBLE (1)
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#define CPUFREQ_NOTIFY (2)
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#define CPUFREQ_START (3)
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#define CPUFREQ_UPDATE_POLICY_CPU (4)
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#define CPUFREQ_SHARED_TYPE_NONE (0) /* None */
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#define CPUFREQ_SHARED_TYPE_HW (1) /* HW does needed coordination */
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void cpufreq_frequency_table_get_attr(struct cpufreq_frequency_table *table,
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unsigned int cpu);
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void cpufreq_frequency_table_update_policy_cpu(struct cpufreq_policy *policy);
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void cpufreq_frequency_table_put_attr(unsigned int cpu);
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#endif /* _LINUX_CPUFREQ_H */
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