linux-kernel - Re: [PATCH 1/2] i386: mce cleanup part1: functional change

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Message-ID: <20071009160605.GC13205@amd.com>
Date:	Tue, 9 Oct 2007 18:06:05 +0200
From:	"Joerg Roedel" <joerg.roedel@....com>
To:	"Oleg Verych" <olecom@...wer.upol.cz>
cc:	"Andi Kleen" <andi@...stfloor.org>,
	"Christoph Egger" <Christoph.Egger@....com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] i386: mce cleanup part1: functional change

On Tue, Oct 09, 2007 at 06:04:48PM +0200, Oleg Verych wrote:
> * Tue,  9 Oct 2007 14:49:55 +0200
> 
> []
> > @@ -33,9 +33,20 @@ void fastcall (*machine_check_vector)(struct pt_regs *, long error_code) = unexp
> >  /* This has to be run for each processor */
> >  void mcheck_init(struct cpuinfo_x86 *c)
> >  {
> > +	uint32_t mca, mce;
> > +
> >  	if (mce_disabled==1)
> >  		return;
> >  
> > +	mca = cpu_has(c, X86_FEATURE_MCA);
> > +	mce = cpu_has(c, X86_FEATURE_MCE);
> > +
> > +	if (!mca || !mce) {
> > +		printk(KERN_INFO "CPU%i: No machine check support available\n",
> > +			smp_processor_id());
> > +		return;
> > +	}
> > +
> 
> cpu_has() returns int,
> but would it be better to have something like
> 
>   	if (!mce_disabled &&
> 	    !(c->x86_capability & (X86_FEATURE_MCA | X86_FEATURE_MCE)) {
> 		printk(KERN_INFO "CPU%i: No machine check support available\n",
> 			smp_processor_id());

This looks complicated and is harder to read. Its exactly the purpose of the
cpu_has() macro to avoid such constructs.

> 		return;
> 	} else
> 		return;

Return unconditionaly here?

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