Re: [PATCH v2 3/5] cpuidle: psci: Do not suspend topology CPUs on PREEMPT_RT

[Sebastian Andrzej Siewior]

On 2022-12-19 16:15:01 [+0100], Krzysztof Kozlowski wrote:
> diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
> index 57bc3e3ae391..9d971cc4b12b 100644
> --- a/drivers/cpuidle/cpuidle-psci.c
> +++ b/drivers/cpuidle/cpuidle-psci.c
> @@ -72,7 +72,7 @@ static int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
>  	ct_irq_enter_irqson();
>  	if (s2idle)
>  		dev_pm_genpd_suspend(pd_dev);
> -	else
> +	else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
>  		pm_runtime_put_sync_suspend(pd_dev);

So based on the commit description you run into a sleeping lock in
pm_runtime_put_sync_suspend() while the CPU is in an IRQ-off region.
Why is it okay to skip it on PREEMPT_RT?

>  	ct_irq_exit_irqson();
>  

Sebastian