Re: [PATCH RESEND v10 5/8] ACPI: Centralize acpi_get_cpu_uid() declaration in include/linux/acpi.h

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Build breakage when CONFIG_ACPI is disabled due to missing acpi_get_cpu_uid() stub.
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--- Patch [5]: [PATCH RESEND v10 5/8] ACPI: Centralize acpi_get_cpu_uid() declaration in include/linux/acpi.h ---
commit f99931b839a856d11d22796fd0c23424af139915
Author: Chengwen Feng <fengchengwen@huawei.com>

ACPI: Centralize acpi_get_cpu_uid() declaration in include/linux/acpi.h

This commit centralizes the acpi_get_cpu_uid() declaration into the global
scope in include/linux/acpi.h and removes the architecture-specific
declarations. This unifies the interface and eliminates duplicate prototypes.

> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index fbf0c3a65f598..f7e50e9cfb224 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
[ ... ]
> @@ -323,6 +323,17 @@ int acpi_unmap_cpu(int cpu);
>  
>  acpi_handle acpi_get_processor_handle(int cpu);
>  
> +/**
> + * acpi_get_cpu_uid() - Get ACPI Processor UID of from MADT table
> + * @cpu: Logical CPU number (0-based)
> + * @uid: Pointer to store ACPI Processor UID
> + *
> + * Return: 0 on success (ACPI Processor ID stored in *uid);
> + *         -EINVAL if CPU number is invalid or out of range;
> + *         -ENODEV if ACPI Processor UID for the CPU is not found.
> + */
> +int acpi_get_cpu_uid(unsigned int cpu, u32 *uid);
> +

[Severity: Low]
Does this cause a build failure when CONFIG_ACPI is disabled? The declaration
is added here, but it appears there is no static inline stub provided in the
!CONFIG_ACPI section of the header.

Callers outside of ACPI-specific code seem to use this function
unconditionally. For example, in arch/x86/xen/enlighten_hvm.c within
xen_cpu_up_prepare_hvm():

    if (acpi_get_cpu_uid(cpu, &cpu_uid) == 0)

Without a static inline stub returning an error code (like -ENODEV) when
CONFIG_ACPI is not set, does compiling x86 with CONFIG_XEN_PVHVM enabled and
CONFIG_ACPI disabled result in an implicit function declaration and undefined
reference linker error?

>  #ifdef CONFIG_ACPI_HOTPLUG_IOAPIC
>  int acpi_get_ioapic_id(acpi_handle handle, u32 gsi_base, u64 *phys_addr);
>  #endif

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Sashiko AI review · https://sashiko.dev/#/patchset/20260401081640.26875-1-fengchengwen@huawei.com?part=5