linux-kernel - Re: [PATCH 4/6] x86/cpufreq: use cpumask

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Message-ID: <alpine.LFD.2.01.0906090842120.6847@localhost.localdomain>
Date:	Tue, 9 Jun 2009 08:46:44 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Rusty Russell <rusty@...tcorp.com.au>
cc:	Yinghai Lu <yinghai@...nel.org>, Avi Kivity <avi@...hat.com>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dave Jones <davej@...hat.com>, cpufreq@...r.kernel.org
Subject: Re: [PATCH 4/6] x86/cpufreq: use cpumask_copy instead of =

On Tue, 9 Jun 2009, Rusty Russell wrote:
>  
>  	for_each_online_cpu(i) {
> -		if (check_supported_cpu(i))
> +		if (work_on_cpu(i, check_supported_cpu, NULL) == 0)
>  			supported_cpus++;

Please STOP USING THAT HORRIBLE "work_on_cpu()" crap.

Is there any reason you do that? We've had to fix up the fallout from that 
kind of crazy crap several times.

Just use a regular IPI. Use "smp_call_function_[single|many]()" instead.

See for example commit 01599fca6758d2cd133e78f87426fc851c9ea725, where 
another "work_on_cpu()" thing was broken.

I don't understand why you guys keep on using that _known_ bad function. 
The whole point of "work_on_cpu()" is for big, slow, and rare things. Not 
as a random "let's make that CPU do this".

So stop it. 

			Linus
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