linux-kernel - Re: [PATCH v2 3/7] ACPI / processor: Introduce invalid_logical

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Date:	Tue, 05 May 2015 14:01:02 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Hanjun Guo <hanjun.guo@...aro.org>
Cc:	Will Deacon <will.deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Sudeep Holla <Sudeep.Holla@....com>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linaro-acpi@...ts.linaro.org
Subject: Re: [PATCH v2 3/7] ACPI / processor: Introduce invalid_logical_cpuid()

On Tuesday, May 05, 2015 10:46:34 AM Hanjun Guo wrote:
> In ACPI processor drivers, we use direct comparisons of cpu logical
> id with -1 which are error prone in case logical cpuid is accidentally
> assinged an error code and prevents us from returning an error-encoding
> cpuid directly in some cases.
> 
> So introduce invalid_logical_cpuid() to identify cpu with invalid
> logical cpu num, then it will be used to replace the direct comparisons
> with -1.
> 
> Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> ---
>  drivers/acpi/acpi_processor.c | 4 ++--
>  drivers/acpi/processor_pdc.c  | 5 +----
>  include/linux/acpi.h          | 5 +++++
>  3 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index 95492d0..62c846b 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -274,7 +274,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
>  		 * Handle UP system running SMP kernel, with no CPU
>  		 * entry in MADT
>  		 */
> -		if ((pr->id == -1) && (num_online_cpus() == 1))
> +		if (invalid_logical_cpuid(pr->id) && (num_online_cpus() == 1))
>  			pr->id = 0;
>  	}
>  
> @@ -283,7 +283,7 @@ static int acpi_processor_get_info(struct acpi_device *device)
>  	 *  less than the max # of CPUs. They should be ignored _iff
>  	 *  they are physically not present.
>  	 */
> -	if (pr->id == -1) {
> +	if (invalid_logical_cpuid(pr->id)) {
>  		int ret = acpi_processor_hotadd_init(pr);
>  		if (ret)
>  			return ret;
> diff --git a/drivers/acpi/processor_pdc.c b/drivers/acpi/processor_pdc.c
> index e5dd808..6dd98d0 100644
> --- a/drivers/acpi/processor_pdc.c
> +++ b/drivers/acpi/processor_pdc.c
> @@ -52,10 +52,7 @@ static bool __init processor_physically_present(acpi_handle handle)
>  	type = (acpi_type == ACPI_TYPE_DEVICE) ? 1 : 0;
>  	cpuid = acpi_get_cpuid(handle, type, acpi_id);
>  
> -	if (cpuid == -1)
> -		return false;
> -
> -	return true;
> +	return invalid_logical_cpuid(cpuid) ? false : true;

What about

	return !invalid_logical_cpuid(cpuid);


>  }
>  
>  static void acpi_set_pdc_bits(u32 *buf)
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index e4da5e3..913b49f 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -158,6 +158,11 @@ typedef u32 phys_cpuid_t;
>  #define PHYS_CPUID_INVALID (phys_cpuid_t)(-1)
>  #endif
>  
> +static inline bool invalid_logical_cpuid(u32 cpuid)
> +{
> +	return (int)cpuid < 0;
> +}
> +
>  #ifdef CONFIG_ACPI_HOTPLUG_CPU
>  /* Arch dependent functions for cpu hotplug support */
>  int acpi_map_cpu(acpi_handle handle, phys_cpuid_t physid, int *pcpu);
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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