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

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Message-ID: <CAJZ5v0hD1qz1RDQpj47fkK4p_q2xSB84kx6bCenj4P6s-n9HsQ@mail.gmail.com>
Date:   Tue, 23 Mar 2021 19:55:12 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Lukasz Luba <lukasz.luba@....com>
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>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Ionela Voinescu <ionela.voinescu@....com>,
        Dietmar Eggemann <Dietmar.Eggemann@....com>
Subject: Re: [PATCH] PM / EM: postpone creating the debugfs dir till fs_initcall

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!