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Date: Wed, 24 Jul 2013 10:25:26 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: rjw@...k.pl, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, cpufreq@...r.kernel.org,
kyungmin.park@...sung.com, myungjoo.ham@...sung.com,
Lists linaro-kernel <linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH 1/3 v6] cpufreq: Add debugfs directory for cpufreq
Hi Viresh,
On 07/22/2013 07:11 PM, Viresh Kumar wrote:
> On 18 July 2013 16:47, Chanwoo Choi <cw00.choi@...sung.com> wrote:
>> +#ifdef CONFIG_CPU_FREQ_STAT
>> +/* The cpufreq_debugfs is used to create debugfs root directory for CPUFreq. */
>> +static struct dentry *cpufreq_debugfs;
>> +
>> +static int cpufreq_create_debugfs_dir(struct cpufreq_policy *policy,
>> + struct device *dev)
>> +{
>> + char name[CPUFREQ_NAME_LEN];
>> + unsigned int cpus, size, idx;
>> +
>> + if (!cpufreq_debugfs)
>> + return -EINVAL;
>> +
>> + cpus = cpumask_weight(policy->cpus);
>
> I remember I told you not to use policy->cpus for this purpose?? But
> related_cpus.
You're right. I'll use policy->related_cpus instead of policy->cpus.
>
>> + idx = cpus > 1 ? policy->cpu : 0;
>
>> + policy->cpu_debugfs[idx] = debugfs_create_dir(name, cpufreq_debugfs);
>
> This is broken. A policy may contain cpus 9,10 only.. You will allocate array
> for 2 cpus and try to access cpu_debugfs[9] :)
Right, I'll consider other method to resolve issue related to index of array.
>
>> + if (!policy->cpu_debugfs[idx]) {
>> + pr_err("creating debugfs directory failed\n");
>> + return -ENODEV;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int cpufreq_create_debugfs_symlink(struct cpufreq_policy *policy,
>> + unsigned int src_cpu,
>> + unsigned int dest_cpu)
>
> Only use policy and cpu for which symlink has to be created as param
> to this routine. And create link to policy->cpu.
>
OK, I'll simplify function prototype(cpufreq_create_debugfs_symlink) by removing
unnecessary parameter.
>> +{
>> + char symlink_name[CPUFREQ_NAME_LEN];
>> + char target_name[CPUFREQ_NAME_LEN];
>> +
>> + if (!cpufreq_debugfs)
>> + return -EINVAL;
>> +
>> + if (!policy->cpu_debugfs[src_cpu])
>> + return -EINVAL;
>> +
>> + sprintf(symlink_name, "cpu%d", dest_cpu);
>> + sprintf(target_name, "./cpu%d", src_cpu);
>> + policy->cpu_debugfs[dest_cpu] = debugfs_create_symlink(
>> + symlink_name,
>> + cpufreq_debugfs,
>> + target_name);
>> + if (!policy->cpu_debugfs[dest_cpu]) {
>> + pr_err("creating debugfs symlink failed\n");
>> + return -ENODEV;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void cpufreq_remove_debugfs_dir(struct cpufreq_policy *policy,
>> + unsigned int cpu)
>> +{
>> + unsigned int idx = cpumask_weight(policy->cpus) > 1 ? cpu : 0;
>> +
>> + if (!policy->cpu_debugfs[idx])
>> + return;
>> +
>> + debugfs_remove_recursive(policy->cpu_debugfs[idx]);
>
> Whey do we need recursive here? And what exactly does recursive will
> do?
>
If cpu is last user of policy, __cpufreq_remove_dev() have to remove debugfs directory
and child file/directory of root debugfs directory. So, I used debugfs_remove_recursive() function.
>> +}
>> +
>
> same problem here too.
>> +static void cpufreq_move_debugfs_dir(struct cpufreq_policy *policy,
>> + unsigned int new_cpu)
>> +{
>> + struct dentry *old_entry, *new_entry;
>> + char new_dir_name[CPUFREQ_NAME_LEN];
>> + unsigned int j, old_cpu = policy->cpu;
>> +
>> + if (!policy->cpu_debugfs[new_cpu])
>> + return;
>> +
>> + /*
>> + * Remove symbolic link of debugfs directory except for debugfs
>> + * directory of old_cpu.
>> + */
>> + for_each_present_cpu(j) {
>> + if (old_cpu == j)
>> + continue;
>> +
>> + debugfs_remove(policy->cpu_debugfs[j]);
>
> Why you need this? We aren't removing the earlier dentry at all here.
>
>> + }
>> +
>> + /*
>> + * Change debugfs directory name from as following:
>> + * - old debugfs dir name : /sys/kernel/debugfs/cpufreq/cpu${old_cpu}
>> + * - new debugfs dir name : /sys/kernel/debugfs/cpufreq/cpu${new_cpu}
>> + */
>> + sprintf(new_dir_name, "cpu%d", new_cpu);
>> + old_entry = policy->cpu_debugfs[old_cpu];
>> + new_entry = debugfs_rename(cpufreq_debugfs, old_entry,
>> + cpufreq_debugfs, new_dir_name);
>
> This routine returns old_entry only.. and so you can simply create a
> single routine with name dentry.
I used 'new_entry' variable to improve readability to distinguish between old_entry and new_entry.
But, as your comment, I'll simplify this statement to remove unnecessary code.
>
>> + if (!new_entry) {
>> + pr_err("changing debugfs directory name failed\n");
>> + goto err_rename;
>> + }
>> +
>> + policy->cpu_debugfs[new_cpu] = new_entry;
>> + policy->cpu_debugfs[old_cpu] = NULL;
>> +
>> + /* Create again symbolic link of debugfs directory */
>> + for_each_present_cpu(j) {
>
> present_cpu?? We discussed this before.. You will break multi cluster
> systems.
My mistake. I'll use for_each_cpu() macro instead of for_each_present_cpu().
>
>> + if (new_cpu == j)
>> + continue;
>> +
>> + cpufreq_create_debugfs_symlink(policy, new_cpu, j);
>> + }
>> +
>> + return;
>> +
>> +err_rename:
>> + for_each_present_cpu(j) {
>> + if (old_cpu == j)
>> + continue;
>> +
>> + cpufreq_create_debugfs_symlink(policy, old_cpu, j);
>> + }
>> +}
>> +
>> +static int cpufreq_create_debugfs(void)
>> +{
>> + cpufreq_debugfs = debugfs_create_dir("cpufreq", NULL);
>> + if (!cpufreq_debugfs) {
>> + pr_err("creating debugfs root failed\n");
>> + return -ENODEV;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void cpufreq_remove_debugfs(void)
>> +{
>> + if (cpufreq_debugfs)
>> + debugfs_remove_recursive(cpufreq_debugfs);
>> +}
>> +#else
>> +static int cpufreq_create_debugfs_dir(struct cpufreq_policy *policy,
>> + struct device *dev) { return 0; }
>> +static int cpufreq_create_debugfs_symlink(struct cpufreq_policy *policy,
>> + unsigned int src_cpu,
>> + unsigned int dest_cpu) { return 0;}
>> +static void cpufreq_remove_debugfs_dir(struct cpufreq_policy *policy,
>> + unsigned int cpu) { }
>> +static void cpufreq_move_debugfs_dir(struct cpufreq_policy *policy,
>> + unsigned int new_cpu) { }
>> +static int cpufreq_create_debugfs(void) { return 0; }
>> +static void cpufreq_remove_debugfs(void) { }
>
> make all above #else part routines inline.
OK.
>
>> +#endif
>> +
>> /* symlink affected CPUs */
>> static int cpufreq_add_dev_symlink(unsigned int cpu,
>> struct cpufreq_policy *policy)
>> @@ -726,6 +885,8 @@ static int cpufreq_add_dev_symlink(unsigned int cpu,
>> cpufreq_cpu_put(managed_policy);
>> return ret;
>> }
>> +
>> + cpufreq_create_debugfs_symlink(policy, cpu, j);
>> }
>> return ret;
>> }
>> @@ -777,6 +938,9 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
>> }
>> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>>
>> + /* prepare interface data for debugfs */
>> + cpufreq_create_debugfs_dir(policy, dev);
>> +
>> ret = cpufreq_add_dev_symlink(cpu, policy);
>> if (ret)
>> goto err_out_kobj_put;
>> @@ -839,6 +1003,8 @@ static int cpufreq_add_policy_cpu(unsigned int cpu, unsigned int sibling,
>> return ret;
>> }
>>
>> + cpufreq_create_debugfs_symlink(policy, sibling, cpu);
>> +
>> return 0;
>> }
>> #endif
>> @@ -1046,6 +1212,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
>>
>> if (cpu != data->cpu) {
>> sysfs_remove_link(&dev->kobj, "cpufreq");
>> + cpufreq_remove_debugfs_dir(data, cpu);
>> } else if (cpus > 1) {
>> /* first sibling now owns the new sysfs dir */
>> cpu_dev = get_cpu_device(cpumask_first(data->cpus));
>> @@ -1068,6 +1235,8 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
>> return -EINVAL;
>> }
>>
>> + cpufreq_move_debugfs_dir(data, cpu_dev->id);
>> +
>> WARN_ON(lock_policy_rwsem_write(cpu));
>> update_policy_cpu(data, cpu_dev->id);
>> unlock_policy_rwsem_write(cpu);
>> @@ -1089,6 +1258,8 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
>> unlock_policy_rwsem_read(cpu);
>> kobject_put(kobj);
>>
>> + cpufreq_remove_debugfs_dir(data, cpu);
>> +
>> /* we need to make sure that the underlying kobj is actually
>> * not referenced anymore by anybody before we proceed with
>> * unloading.
>> @@ -1894,6 +2065,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
>> cpufreq_driver = driver_data;
>> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>>
>> + cpufreq_create_debugfs();
>
> Why you moved this to register_driver? It was fine at cpufreq_core_init()
If we moved this to cpufreq_core_int(), I have to create cpufreq_core_exit().
Do you agree about creating cpufreq_core_exit()(?
>
>> ret = subsys_interface_register(&cpufreq_interface);
>> if (ret)
>> goto err_null_driver;
>> @@ -1918,12 +2091,14 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
>> }
>>
>> register_hotcpu_notifier(&cpufreq_cpu_notifier);
>> +
>
> unrelated change.
OK, I'll remove it.
>
>> pr_debug("driver %s up and running\n", driver_data->name);
>>
>> return 0;
>> err_if_unreg:
>> subsys_interface_unregister(&cpufreq_interface);
>> err_null_driver:
>> + cpufreq_remove_debugfs();
>> write_lock_irqsave(&cpufreq_driver_lock, flags);
>> cpufreq_driver = NULL;
>> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>> @@ -1949,6 +2124,8 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
>>
>> pr_debug("unregistering driver %s\n", driver->name);
>>
>> + cpufreq_remove_debugfs();
>
> And so you don't need this.
>
>> subsys_interface_unregister(&cpufreq_interface);
>> unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
>>
>> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
>> index 037d36a..825f379 100644
>> --- a/include/linux/cpufreq.h
>> +++ b/include/linux/cpufreq.h
>> @@ -115,6 +115,7 @@ struct cpufreq_policy {
>>
>> struct kobject kobj;
>> struct completion kobj_unregister;
>> + struct dentry **cpu_debugfs;
>> };
>>
>> #define CPUFREQ_ADJUST (0)
>> --
>> 1.8.0
>>
>
Thanks for your comment.
Best Regards,
Chanwoo Choi
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