linux-kernel - Re: [PATCH v7 04/16] ACPI: processor: Move checks and availability of acpi

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Date: Thu, 25 Apr 2024 09:20:31 +0800
From: Hanjun Guo <guohanjun@...wei.com>
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 04/16] ACPI: processor: Move checks and availability of
 acpi_processor earlier

On 2024/4/25 1:18, Jonathan Cameron wrote:
> On Tue, 23 Apr 2024 19:53:34 +0800
> Hanjun Guo <guohanjun@...wei.com> wrote:
> 
>>> @@ -232,6 +263,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
>>>    	acpi_status status = AE_OK;
>>>    	static int cpu0_initialized;
>>>    	unsigned long long value;
>>> +	int ret;
>>>    
>>>    	acpi_processor_errata();
>>>    
>>> @@ -316,10 +348,12 @@ 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);
>>> +		ret = acpi_processor_hotadd_init(pr, device);
>>>    
>>>    		if (ret)
>>> -			return ret;
>>> +			goto err;
>>> +	} else {
>>> +		acpi_processor_set_per_cpu(pr, device);
>>>    	}
>>>    
>>>    	/*
>>> @@ -357,6 +391,10 @@ static int acpi_processor_get_info(struct acpi_device *device)
>>>    		arch_fix_phys_package_id(pr->id, value);
>>>    
>>>    	return 0;
>>> +
>>> +err:
>>> +	per_cpu(processors, pr->id) = NULL;
>>
>> ...
>>
>>> +	return ret;
>>>    }
>>>    
>>>    /*
>>> @@ -365,8 +403,6 @@ static int acpi_processor_get_info(struct acpi_device *device)
>>>     * (cpu_data(cpu)) values, like CPU feature flags, family, model, etc.
>>>     * Such things have to be put in and set up by the processor driver's .probe().
>>>     */
>>> -static DEFINE_PER_CPU(void *, processor_device_array);
>>> -
>>>    static int acpi_processor_add(struct acpi_device *device,
>>>    					const struct acpi_device_id *id)
>>>    {
>>> @@ -395,28 +431,6 @@ static int acpi_processor_add(struct acpi_device *device,
>>>    	if (result) /* Processor is not physically present or unavailable */
>>>    		return 0;
>>>    
>>> -	BUG_ON(pr->id >= nr_cpu_ids);
>>> -
>>> -	/*
>>> -	 * Buggy BIOS check.
>>> -	 * ACPI id of processors can be reported wrongly by the BIOS.
>>> -	 * Don't trust it blindly
>>> -	 */
>>> -	if (per_cpu(processor_device_array, pr->id) != NULL &&
>>> -	    per_cpu(processor_device_array, pr->id) != device) {
>>> -		dev_warn(&device->dev,
>>> -			"BIOS reported wrong ACPI id %d for the processor\n",
>>> -			pr->id);
>>> -		/* Give up, but do not abort the namespace scan. */
>>> -		goto err;
>>> -	}
>>> -	/*
>>> -	 * processor_device_array is not cleared on errors to allow buggy BIOS
>>> -	 * checks.
>>> -	 */
>>> -	per_cpu(processor_device_array, pr->id) = device;
>>> -	per_cpu(processors, pr->id) = pr;
>>
>> Nit: seems we need to remove the duplicated
>> per_cpu(processors, pr->id) = NULL; in acpi_processor_add():
>>
>> --- a/drivers/acpi/acpi_processor.c
>> +++ b/drivers/acpi/acpi_processor.c
>> @@ -446,7 +446,6 @@ static int acpi_processor_add(struct acpi_device
>> *device,
>>     err:
>>           free_cpumask_var(pr->throttling.shared_cpu_map);
>>           device->driver_data = NULL;
>> -       per_cpu(processors, pr->id) = NULL;
> 
> I don't follow.  This path is used if processor_get_info() succeeded and
> we later fail.  I don't see where the the duplication is?

It is! Thanks for the clarification.

Thanks
Hanjun