linux-kernel - Re: [PATCH] x86: Issue a warning if number of present CPUs > maxcpus and CONFIG

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Message-ID: <20140216171159.GB25047@pd.tnic>
Date:	Sun, 16 Feb 2014 18:11:59 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Petr Tesarik <ptesarik@...e.cz>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Jan Beulich <jbeulich@...e.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Issue a warning if number of present CPUs > maxcpus
 and CONFIG_HOTPLUG=n

On Sat, Feb 15, 2014 at 03:02:23PM +0100, Petr Tesarik wrote:
> Note that the check against i (value passed as maxcpus, but at least 1)
> is repeated further down, including the warning, but since possible is
> already clamped to max_cpus at that time, it is never printed. In fact,
> for the non-hotplug case, the warning about exceeding maxcpus is only
> ever printed if "possible_cpus" was also specified on the command line.
> 
> I strongly believe that such limitation was unintentional.
> 
> I also changed the message slightly -- the kernel parameter name is
> maxcpus, not max_cpus.
> 
> Signed-off-by: Petr Tesarik <ptesarik@...e.cz>
> ---
>  arch/x86/kernel/smpboot.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index a32da80..376b6c6 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1226,9 +1226,6 @@ __init void prefill_possible_map(void)
>  #ifdef CONFIG_HOTPLUG_CPU
>  		if (setup_max_cpus)
>  			possible += disabled_cpus;
> -#else
> -		if (possible > i)
> -			possible = i;

Hmm, ok, this function is not the easiest to parse and provided I'm not
missing some corner case, the cleanup makes sense to me.

Acked-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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