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Message-ID: <b8f430c1-c30f-191f-18c6-f750fa6ba476@redhat.com>
Date:   Mon, 18 Sep 2023 15:50:09 +1000
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Subject: Re: [RFC PATCH v2 20/35] ACPI: Rename acpi_processor_hotadd_init and
 remove pre-processor guards
Content-Language: en-US
To:     Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
        James Morse <james.morse@arm.com>
Cc:     linux-pm@vger.kernel.org, loongarch@lists.linux.dev,
        linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-riscv@lists.infradead.org, kvmarm@lists.linux.dev,
        x86@kernel.org, Salil Mehta <salil.mehta@huawei.com>,
        Russell King <linux@armlinux.org.uk>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        jianyong.wu@arm.com, justin.he@arm.com
References: <20230913163823.7880-1-james.morse@arm.com>
 <20230913163823.7880-21-james.morse@arm.com>
 <20230914151720.00007105@Huawei.com>
From:   Gavin Shan <gshan@redhat.com>
In-Reply-To: <20230914151720.00007105@Huawei.com>
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On 9/15/23 00:17, Jonathan Cameron wrote:
> On Wed, 13 Sep 2023 16:38:08 +0000
> James Morse <james.morse@arm.com> 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@arm.com>
>> ---
>>   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