linux-kernel - Re: [PATCH 3/3] EDAC: carve out AMD MCE decoding logic

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Date:	Fri, 2 Oct 2009 20:47:14 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Borislav Petkov <borislav.petkov@....com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Borislav Petkov <petkovbb@...glemail.com>,
	Andi Kleen <andi@...stfloor.org>, x86@...nel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] EDAC: carve out AMD MCE decoding logic


* Borislav Petkov <borislav.petkov@....com> wrote:

> On Fri, Oct 02, 2009 at 03:39:54PM +0200, Ingo Molnar wrote:
> > I suspect this is fine currently because no two EDAC modules should be 
> > active at the same time. A followup cleanup patch would be nice 
> > nevertheless that uses a notifier chain here with proper 
> > register/unregister locking.
> 
> Please do elaborate for I can't seem to follow.
> 
> AFAICT, we are going to have max one MCE decoder at any one time so no 
> need to notify it.
> 
> The x86_mce_decode_callback assignment probably needs locking just to 
> be on the safe side. We can do a
> 
> mce_set_decode_callback(void (*f)(struct mce*m))
> 
> helper which falls back to default_decode_mce() whenever its being 
> passed a NULL for *f using proper locking...
> 
> I'm pretty sure I'm missing something though...

No, the locking was all that i meant. Using atomic_notifier would solve 
that. Make the default decoder low-prio, that way there's no need to do 
the callback save/restore sequence either.

	Ingo
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