Re: [RFC PATCH v2 20/35] ACPI: Rename acpi_processor_hotadd_init and remove pre-processor guards

[Gavin Shan <gshan@xxxxxxxxxx>]

On 9/15/23 00:17, Jonathan Cameron wrote:
> On Wed, 13 Sep 2023 16:38:08 +0000
> James Morse <james.morse@xxxxxxx> wrote:
>
> > acpi_processor_hotadd_init() will make a CPU present by mapping it
> > based on its hardware id.
> >
> > 'hotadd_init' is ambiguous once there are two different behaviours
> > for cpu hotplug. This is for toggling the _STA present bit. Subsequent
> > patches will add support for toggling the _STA enabled bit, named
> > acpi_processor_make_enabled().
> >
> > Rename it acpi_processor_make_present() to make it clear this is
> > for CPUs that were not previously present.
> >
> > Expose the function prototypes it uses to allow the preprocessor
> > guards to be removed. The IS_ENABLED() check will let the compiler
> > dead-code elimination pass remove this if it isn't going to be
> > used.
> >
> > Signed-off-by: James Morse <james.morse@xxxxxxx>
> > ---
> >   drivers/acpi/acpi_processor.c | 14 +++++---------
> >   include/linux/acpi.h          |  2 --
> >   2 files changed, 5 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> > index 75257fae10e7..22a15a614f95 100644
> > --- a/drivers/acpi/acpi_processor.c
> > +++ b/drivers/acpi/acpi_processor.c
> > @@ -182,13 +182,15 @@ static void __init acpi_pcc_cpufreq_init(void) {}
> >   #endif /* CONFIG_X86 */
> >   
> >   /* Initialization */
> > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
> > -static int acpi_processor_hotadd_init(struct acpi_processor *pr)
> > +static int acpi_processor_make_present(struct acpi_processor *pr)
> >   {
> >   	unsigned long long sta;
> >   	acpi_status status;
> >   	int ret;
> >   
> > +	if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))
> > +		return -ENODEV;
> > +
> >   	if (invalid_phys_cpuid(pr->phys_id))
> >   		return -ENODEV;
> >   
> > @@ -222,12 +224,6 @@ static int acpi_processor_hotadd_init(struct acpi_processor *pr)
> >   	cpu_maps_update_done();
> >   	return ret;
> >   }
> > -#else
> > -static inline int acpi_processor_hotadd_init(struct acpi_processor *pr)
> > -{
> > -	return -ENODEV;
> > -}
> > -#endif /* CONFIG_ACPI_HOTPLUG_PRESENT_CPU */
> >   
> >   static int acpi_processor_get_info(struct acpi_device *device)
> >   {
> > @@ -335,7 +331,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
> >   	 *  because cpuid <-> apicid mapping is persistent now.
> >   	 */
> >   	if (invalid_logical_cpuid(pr->id) || !cpu_present(pr->id)) {
> > -		int ret = acpi_processor_hotadd_init(pr);
> > +		int ret = acpi_processor_make_present(pr);
> >   
> >   		if (ret)
> >   			return ret;
> > diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> > index 651dd43976a9..b7ab85857bb7 100644
> > --- a/include/linux/acpi.h
> > +++ b/include/linux/acpi.h
> > @@ -316,12 +316,10 @@ static inline int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
> >   }
> >   #endif
> >   
> > -#ifdef CONFIG_ACPI_HOTPLUG_PRESENT_CPU
> >   /* Arch dependent functions for cpu hotplug support */
> >   int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, u32 acpi_id,
> >   		 int *pcpu);
> >   int acpi_unmap_cpu(int cpu);
>
> I've lost track somewhat but I think the definitions of these are still under ifdefs
> which is messy if nothing else and might cause build issues.

Yup, it's not safe to use 'if (!IS_ENABLED(CONFIG_ACPI_HOTPLUG_PRESENT_CPU))' in
acpi_processor_make_present() until the ifdefs are removed for those two functions
in individual architectures.

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

Thanks,
Gavin