linux-kernel - Re: [PATCH] x86/acpi: Fix a warning message in logical CPU IDs allocation

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Date:   Wed, 1 Mar 2017 18:09:34 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     Ingo Molnar <mingo@...nel.org>
CC:     <tglx@...utronix.de>, <hpa@...or.com>, <bp@...en8.de>,
        <wanpeng.li@...mail.com>, <nicstange@...il.com>, <x86@...nel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/acpi: Fix a warning message in logical CPU IDs
 allocation

Hi Ingo,

At 03/01/2017 05:10 PM, Ingo Molnar wrote:
>
> * Dou Liyang <douly.fnst@...fujitsu.com> wrote:
>
>> Current warning message regarded the "nr_cpu_ids - 1" as the limit
>> number of the CPUs. It may be confused us, for example:
>> we have two CPUs, nr_cpu_ids = 2, but the warning message may
>> indicate that we just have 1 CPU, which likes that:
>>     Only 1 processors supported.Processor 2/0x2 and the rest
>>     are ignored.
>>
>> Fix the warning message, replace "nr_cpu_ids - 1" with "nr_cpu_ids".
>> And the warning message can be like that:
>>     APIC: NR_CPUS/possible_cpus limit of 2 reached. Processor 2/0x2
>>     and the rest are ignored.
>>
>> Signed-off-by: Dou Liyang <douly.fnst@...fujitsu.com>
>
> The patch is correct, but the title is wrong (it's 'apic', not 'acpi'), plus the
> changelog is unreadable. Furthermore the changelog does not declare the changing
> of the return code to -EINVAL ...
>
> I fixed all that in the commit below, but please be more careful in the future.
>

Got it! I see, I will be more careful. :)

Thanks,
	Liyang.

> Thanks,
>
> 	Ingo
>
> =======================>
>>>From bb3f0a52630c84807fca9bdd76ac2f5dcec82689 Mon Sep 17 00:00:00 2001
> From: Dou Liyang <douly.fnst@...fujitsu.com>
> Date: Tue, 28 Feb 2017 13:50:52 +0800
> Subject: [PATCH] x86/apic: Fix a warning message in logical CPU IDs allocation
>
> The current warning message in allocate_logical_cpuid() is somewhat confusing:
>
>   Only 1 processors supported.Processor 2/0x2 and the rest are ignored.
>
> As it might imply that there's only one CPU in the system - while what we ran
> into here is a kernel limitation.
>
> Fix the warning message to clarify all that:
>
>   APIC: NR_CPUS/possible_cpus limit of 2 reached. Processor 2/0x2 and the rest are ignored.
>
> ( Also update the error return from -1 to -EINVAL, which is the more
>   canonical return value. )
>
> Signed-off-by: Dou Liyang <douly.fnst@...fujitsu.com>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: bp@...en8.de
> Cc: nicstange@...il.com
> Cc: wanpeng.li@...mail.com
> Link: http://lkml.kernel.org/r/1488261052-25753-1-git-send-email-douly.fnst@cn.fujitsu.com
> Signed-off-by: Ingo Molnar <mingo@...nel.org>
> ---
>  arch/x86/kernel/apic/apic.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index 4261b3282ad9..11088b86e5c7 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -2062,10 +2062,10 @@ static int allocate_logical_cpuid(int apicid)
>
>  	/* Allocate a new cpuid. */
>  	if (nr_logical_cpuids >= nr_cpu_ids) {
> -		WARN_ONCE(1, "Only %d processors supported."
> +		WARN_ONCE(1, "APIC: NR_CPUS/possible_cpus limit of %i reached. "
>  			     "Processor %d/0x%x and the rest are ignored.\n",
> -			     nr_cpu_ids - 1, nr_logical_cpuids, apicid);
> -		return -1;
> +			     nr_cpu_ids, nr_logical_cpuids, apicid);
> +		return -EINVAL;
>  	}
>
>  	cpuid_to_apicid[nr_logical_cpuids] = apicid;
>
>
>