linux-kernel - Re: [PATCH v7 05/16] ACPI: processor: Add acpi_get_processor

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Date: Mon, 22 Apr 2024 20:59:38 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: 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>, 
	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 05/16] ACPI: processor: Add acpi_get_processor_handle() helper

On Thu, Apr 18, 2024 at 3:56 PM Jonathan Cameron
<Jonathan.Cameron@...wei.com> wrote:
>
> If CONFIG_ACPI_PROCESSOR provide a helper to retrieve the
> acpi_handle for a given CPU allowing access to methods
> in DSDT.
>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
> v7: No change
> v6: New patch
> ---
>  drivers/acpi/acpi_processor.c | 10 ++++++++++
>  include/linux/acpi.h          |  7 +++++++
>  2 files changed, 17 insertions(+)
>
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index ac7ddb30f10e..127ae8dcb787 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -35,6 +35,16 @@ EXPORT_PER_CPU_SYMBOL(processors);
>  struct acpi_processor_errata errata __read_mostly;
>  EXPORT_SYMBOL_GPL(errata);
>
> +acpi_handle acpi_get_processor_handle(int cpu)
> +{
> +       acpi_handle handle = NULL;

The local var looks redundant.

> +       struct acpi_processor *pr = per_cpu(processors, cpu);;
> +
> +       if (pr)
> +               handle = pr->handle;
> +
> +       return handle;

struct acpi_processor *pr;

pr = per_cpu(processors, cpu);
if (pr)
        return pr->handle;

return NULL;


> +}
>  static int acpi_processor_errata_piix4(struct pci_dev *dev)
>  {
>         u8 value1 = 0;
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 34829f2c517a..9844a3f9c4e5 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -309,6 +309,8 @@ int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id,
>  int acpi_unmap_cpu(int cpu);
>  #endif /* CONFIG_ACPI_HOTPLUG_CPU */
>
> +acpi_handle acpi_get_processor_handle(int cpu);
> +
>  #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
>  int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
>  #endif
> @@ -1077,6 +1079,11 @@ static inline bool acpi_sleep_state_supported(u8 sleep_state)
>         return false;
>  }
>
> +static inline acpi_handle acpi_get_processor_handle(int cpu)
> +{
> +       return NULL;
> +}
> +
>  #endif /* !CONFIG_ACPI */
>
>  extern void arch_post_acpi_subsys_init(void);
> --