linux-kernel - Re: amd_mce.c redundant if check?

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Date:	Wed, 20 Aug 2014 20:57:55 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Adam Duskett <aduskett@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: amd_mce.c redundant if check?

On Wed, Aug 20, 2014 at 11:18:21AM -0600, Adam Duskett wrote:
> I have recently come upon this section of code in
> arch/x86/kernel/cpu/mcheck/mce_amd.c that seems to be a redundant
> unnecessary if check.
> 
> 
> From line 170 - 176:
> 
> if (tr->set_lvt_off) {
> if (lvt_off_valid(tr->b, tr->lvt_off, lo, hi)) {
> /* set new lvt offset */
> hi &= ~MASK_LVTOFF_HI;
> hi |= tr->lvt_off << 20;
> }
> }
> 
> 
> This seems like it's not actually doing anything because it's setting
> the same value that the bit-field already has to itself.

Are you sure?

Just try to find out what MASK_LVTOFF_HI is and then do the operations
with a pen and paper to check whether something else actually happens.

-- 
Regards/Gruss,
    Boris.

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