linux-kernel - Re: [PATCH v7 03/16] ACPI: processor: Drop duplicated check on

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Date: Tue, 23 Apr 2024 14:49:13 +0800
From: Hanjun Guo <guohanjun@...wei.com>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>, Thomas Gleixner
	<tglx@...utronix.de>, Peter Zijlstra <peterz@...radead.org>,
	<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>,
	<kvmarm@...ts.linux.dev>, <x86@...nel.org>, Russell King
	<linux@...linux.org.uk>, "Rafael J . Wysocki" <rafael@...nel.org>, Miguel
 Luis <miguel.luis@...cle.com>, James Morse <james.morse@....com>, Salil Mehta
	<salil.mehta@...wei.com>, Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>
CC: Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave
 Hansen <dave.hansen@...ux.intel.com>, <linuxarm@...wei.com>,
	<justin.he@....com>, <jianyong.wu@....com>
Subject: Re: [PATCH v7 03/16] ACPI: processor: Drop duplicated check on _STA
 (enabled + present)

On 2024/4/18 21:53, Jonathan Cameron wrote:
> The ACPI bus scan will only result in acpi_processor_add() being called
> if _STA has already been checked and the result is that the
> processor is enabled and present.  Hence drop this additional check.
> 
> Suggested-by: Rafael J. Wysocki <rafael@...nel.org>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> 
> ---
> v7: No change
> v6: New patch to drop this unnecessary code. Now I think we only
>      need to explicitly read STA to print a warning in the ARM64
>      arch_unregister_cpu() path where we want to know if the
>      present bit has been unset as well.
> ---
>   drivers/acpi/acpi_processor.c | 6 ------
>   1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index 7fc924aeeed0..ba0a6f0ac841 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -186,17 +186,11 @@ static void __init acpi_pcc_cpufreq_init(void) {}
>   #ifdef CONFIG_ACPI_HOTPLUG_CPU
>   static int acpi_processor_hotadd_init(struct acpi_processor *pr)
>   {
> -	unsigned long long sta;
> -	acpi_status status;
>   	int ret;
>   
>   	if (invalid_phys_cpuid(pr->phys_id))
>   		return -ENODEV;
>   
> -	status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta);
> -	if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_PRESENT))
> -		return -ENODEV;
> -
>   	cpu_maps_update_begin();
>   	cpus_write_lock();

Since the status bits were checked before acpi_processor_add() being
called, do we need to remove the if (!acpi_device_is_enabled(device))
check in acpi_processor_add() as well?

Thanks
Hanjun