Re: [PATCH 1/3 v6] cpufreq: Add debugfs directory for cpufreq

[Chanwoo Choi]

On 07/24/2013 02:05 PM, Viresh Kumar wrote:
> On 24 July 2013 06:55, Chanwoo Choi <cw00.choi@xxxxxxxxxxx> wrote:
>> On 07/22/2013 07:11 PM, Viresh Kumar wrote:
>>> On 18 July 2013 16:47, Chanwoo Choi <cw00.choi@xxxxxxxxxxx> wrote:
> 
>>>> +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.
> 
> You are calling this routine even when we aren't at the last cpu of a policy.
> And so, eventually you are calling this routine for a link you have created.

I'll call proper debugfs_remove*() function according to type of debugfs pointer.
- if cpu is last user of policy, call debugfs_remove_recursive()
- else, call debugfs_remove().

> 
> Have you actually tested your code? What kind of platform? What is cpu
> topology ?? And what exactly you tested..

I tested quad-core EXYNOS4412 SoC based on Cortex-A9 with Tizen platform.
It is opereated on this environment but as you commnet, this test and environment
isn't enough to verify this patchset.
- Testcase1 : Change cpufreq governor on runtime
- Testcase2 : Turn on/off CPU state on runtme

> 
> We are already on v6 and this patch still looks like the v1.. It still has lots
> of basic mistakes, which I don't expect so later in the series..
> 
> Its very difficult for me to review the same patchset again and again.. So,
> normally people might not review it well after v3-v4 and just trust the sender..
> But I am nowhere close to getting that.. And so discouraged to review it..
> 

I'm so sorry about this and thanks for previous your review sincerely.

> Please review/test it well on multiple kind of systems if possible. Test on
> your intel laptop and see if it has multiple policy structures with
> multiple cpus
> in it.. cpuX/cpufreq/related_cpus gives you all cpus that share policy
> structure.

As you comment, I'll modify/test this patchset on various system with enough testcase
and resend this patchset after a thorough review.


> 
>>>> +}
>>>> +
>>>
>>> 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.
> 
> haven't answered this.

The debugfs entry of 'old_cpu' include child debugfs file(e.g., load_table)
If cpu is last user of policy and core call __cpufre_remove_dev() to remove last cpu,
core call cpufreq_move_debugfs_dir(). I have to move the data of debugfs directory/file and
child data for 'old_cpu' to debugfs directory for 'new_cpu'.

If I remove earlier dentry of 'old_cpu', I can't get the child debugfs dir/file.
So I didn't remove the earlier dentry of 'old_cpu'.

> 
>>>> +       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().
> 
> Go through earlier comments about this.. you are still wrong.. You need to
> run over cpus that are in this policy.. i.e. policy->cpus.
> 

OK.

>>>> +               if (new_cpu == j)
>>>> +                       continue;
>>>> +
> 
>>>> @@ -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()(?
> 
> No you don't need that routine. Or in other words there isn't any exit
> for cpufreq core and so this directory must not be removed.
> 

I understood on your previous comment as You said that I had to remove 'cpufreq' debugfs directory
when cpufreq isn't used.

If the core execute cpufreq_create_debugfs() in cpufreq_core_init(),
don't I need to remove 'cpufreq' debugfs directory without cpufreq_core_exit()?

Thanks,
Chanwoo Choi
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