linux-kernel - Re: [PATCH RESEND] cpuidle: psci: Iterate backwards over list in psci_pd

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Date:   Tue, 7 Mar 2023 14:06:31 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Shawn Guo <shawn.guo@...aro.org>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] cpuidle: psci: Iterate backwards over list in psci_pd_remove()

On Sat, Mar 4, 2023 at 8:41 AM Shawn Guo <shawn.guo@...aro.org> wrote:
>
> In case that psci_pd_init_topology() fails for some reason,
> psci_pd_remove() will be responsible for deleting provider and removing
> genpd from psci_pd_providers list.  There will be a failure when removing
> the cluster PD, because the cpu (child) PDs haven't been removed.
>
> [    0.050232] CPUidle PSCI: init PM domain cpu0
> [    0.050278] CPUidle PSCI: init PM domain cpu1
> [    0.050329] CPUidle PSCI: init PM domain cpu2
> [    0.050370] CPUidle PSCI: init PM domain cpu3
> [    0.050422] CPUidle PSCI: init PM domain cpu-cluster0
> [    0.050475] PM: genpd_remove: unable to remove cpu-cluster0
> [    0.051412] PM: genpd_remove: removed cpu3
> [    0.051449] PM: genpd_remove: removed cpu2
> [    0.051499] PM: genpd_remove: removed cpu1
> [    0.051546] PM: genpd_remove: removed cpu0
>
> Fix the problem by iterating the provider list reversely, so that parent
> PD gets removed after child's PDs like below.
>
> [    0.029052] CPUidle PSCI: init PM domain cpu0
> [    0.029076] CPUidle PSCI: init PM domain cpu1
> [    0.029103] CPUidle PSCI: init PM domain cpu2
> [    0.029124] CPUidle PSCI: init PM domain cpu3
> [    0.029151] CPUidle PSCI: init PM domain cpu-cluster0
> [    0.029647] PM: genpd_remove: removed cpu0
> [    0.029666] PM: genpd_remove: removed cpu1
> [    0.029690] PM: genpd_remove: removed cpu2
> [    0.029714] PM: genpd_remove: removed cpu3
> [    0.029738] PM: genpd_remove: removed cpu-cluster0
>
> Fixes: a65a397f2451 ("cpuidle: psci: Add support for PM domains by using genpd")

So I guess there should be Cc: stable for 5.10 and later?

> Reviewed-by: Sudeep Holla <sudeep.holla@....com>
> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
> Signed-off-by: Shawn Guo <shawn.guo@...aro.org>
> ---
> Hi Rafael,
>
> This is a resend of the patch [1].  Could you help pick it up or let me
> know if there is anything need to be improved, thanks!

Is this regarded as 6.3-rc material, or can it wait for 6.4?