linux-kernel - Re: [PATCH] PM / EM: postpone creating the debugfs dir till fs

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Message-ID: <e263e10c-f8ba-a4d4-9f84-142bc87da161@arm.com>
Date:   Wed, 24 Mar 2021 09:39:20 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Ionela Voinescu <ionela.voinescu@....com>,
        Dietmar Eggemann <Dietmar.Eggemann@....com>
Subject: Re: [PATCH] PM / EM: postpone creating the debugfs dir till
 fs_initcall



On 3/23/21 6:55 PM, Rafael J. Wysocki wrote:
> On Tue, Mar 23, 2021 at 4:57 PM Lukasz Luba <lukasz.luba@....com> wrote:
>>
>>
>>
>> On 3/23/21 3:26 PM, Greg KH wrote:
>>> On Tue, Mar 23, 2021 at 02:56:08PM +0000, Lukasz Luba wrote:
>>>> The debugfs directory '/sys/kernel/debug/energy_model' is needed before
>>>> the Energy Model registration can happen. With the recent change in
>>>> debugfs subsystem it's not allowed to create this directory at early stage
>>>> (core_initcall). Thus creating this directory would fail.
>>>> Postpone the creation of the EM debug dir to later stage: fs_initcall.
>>>> It should be safe since all clients: CPUFreq drivers, Devfreq drivers will
>>>> be initialized in later stages.
>>>> The custom debug log below prints the time of creation the EM debug dir at
>>>> fs_initcall and successful registration of EMs at later stages.
>>>>
>>>> [    1.505717] energy_model: creating rootdir
>>>> [    3.698307] cpu cpu0: EM: created perf domain
>>>> [    3.709022] cpu cpu1: EM: created perf domain
>>>>
>>>> fixes: 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized")
>>>> Reported-by: Ionela Voinescu <ionela.voinescu@....com>
>>>> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
>>>> ---
>>>> Hi Rafael,
>>>>
>>>> Please take this patch into your PM v5.12 fixes. The change described in
>>>> the patch above landed in v5.12-rc1. Some of our EAS/EM tests are failing.
>>>
>>> Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>>>
>>
>> Thank you Greg!
> 
> Applied as 5.12-rc material, thanks!
> 

Thank you Rafael!

Regards,
Lukasz