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SubjectRe: [PATCH] cpuidle: psci: Iterate backwards over list in psci_pd_remove()
On Fri, Feb 25, 2022 at 04:24:20PM +0800, Shawn Guo 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 in a reversely order, so

s/reversely/reversed

> that parent PD gets removed before child's PDs.

s/before/after

Essentially, with this change, the PM domains will be removed in the same
order how they were added.

[ 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

Shawn

>
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> ---
> drivers/cpuidle/cpuidle-psci-domain.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
> index ff2c3f8e4668..ce5c415fb04d 100644
> --- a/drivers/cpuidle/cpuidle-psci-domain.c
> +++ b/drivers/cpuidle/cpuidle-psci-domain.c
> @@ -182,7 +182,8 @@ static void psci_pd_remove(void)
> struct psci_pd_provider *pd_provider, *it;
> struct generic_pm_domain *genpd;
>
> - list_for_each_entry_safe(pd_provider, it, &psci_pd_providers, link) {
> + list_for_each_entry_safe_reverse(pd_provider, it,
> + &psci_pd_providers, link) {
> of_genpd_del_provider(pd_provider->node);
>
> genpd = of_genpd_remove_last(pd_provider->node);
> --
> 2.25.1
>

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