linux-kernel - Re: [RFC PATCH v2 17/35] ACPI: processor: Register all CPUs from acpi_processor_get

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Message-ID: <2d0e2fd7-5a6e-04ef-578d-713d8e14c30c@redhat.com>
Date:   Mon, 18 Sep 2023 15:19:01 +1000
From:   Gavin Shan <gshan@...hat.com>
To:     James Morse <james.morse@....com>, linux-pm@...r.kernel.org,
        loongarch@...ts.linux.dev, linux-acpi@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, kvmarm@...ts.linux.dev
Cc:     x86@...nel.org, Salil Mehta <salil.mehta@...wei.com>,
        Russell King <linux@...linux.org.uk>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        jianyong.wu@....com, justin.he@....com
Subject: Re: [RFC PATCH v2 17/35] ACPI: processor: Register all CPUs from
 acpi_processor_get_info()


On 9/14/23 02:38, James Morse wrote:
> To allow ACPI to skip the call to arch_register_cpu() when the _STA
> value indicates the CPU can't be brought online right now, move the
> arch_register_cpu() call into acpi_processor_get_info().
> 
> Systems can still be booted with 'acpi=off', or not include an
> ACPI description at all. For these, the CPUs continue to be
> registered by cpu_dev_register_generic().
> 
> This moves the CPU register logic back to a subsys_initcall(),
> while the memory nodes will have been registered earlier.
> 
> Signed-off-by: James Morse <james.morse@....com>
> ---
>   drivers/acpi/acpi_processor.c | 13 +++++++++++++
>   drivers/base/cpu.c            |  2 +-
>   2 files changed, 14 insertions(+), 1 deletion(-)
> 

With the following nits addressed:

Reviewed-by: Gavin Shan <gshan@...hat.com>

> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index a01e315aa16a..867782bc50b0 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -313,6 +313,19 @@ static int acpi_processor_get_info(struct acpi_device *device)
>   			cpufreq_add_device("acpi-cpufreq");
>   	}
>   
> +	/*
> +	 * Register CPUs that are present.
> +	 * Use get_cpu_device() to skip duplicate CPU descriptions from
> +	 * firmware.
> +	 */
> +	if (!invalid_logical_cpuid(pr->id) && cpu_present(pr->id) &&
> +	    !get_cpu_device(pr->id)) {
> +		int ret = arch_register_cpu(pr->id);
> +
> +		if (ret)
> +			return ret;
> +	}
> +

The multiple lines of comments could be combined a bit:

	/*
	 * Register CPUs that are present. get_cpu_device() is used to
	 * skip duplicate CPU description from firmware.
          */

>   	/*
>   	 *  Extra Processor objects may be enumerated on MP systems with
>   	 *  less than the max # of CPUs. They should be ignored _iff
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index d31c936f0955..677f963e02ce 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -537,7 +537,7 @@ static void __init cpu_dev_register_generic(void)
>   {
>   	int i, ret;
>   
> -	if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES))
> +	if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES) || !acpi_disabled)
>   		return;
>   
>   	for_each_present_cpu(i) {

Some comments may be worthy, to explain why we need "!acpi_disabled" here.

Thanks,
Gavin