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

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Date: Wed, 24 Apr 2024 18:18:57 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Hanjun Guo <guohanjun@...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 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?


>    err_free_pr:
>          kfree(pr);
>          return result;
> 
> Thanks
> Hanjun