linux-kernel - Re: [stable] The SMP alternatives code breaks exception fixup?

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Date:	Thu, 7 Feb 2008 13:16:04 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Greg KH <greg@...ah.com>
cc:	Chuck Ebbert <cebbert@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Gerd Hoffmann <kraxel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Stable Team <stable@...nel.org>
Subject: Re: [stable] The SMP alternatives code breaks exception fixup?

On Wed, 6 Feb 2008, Greg KH wrote:

> On Tue, Jan 22, 2008 at 03:19:33PM -0500, Chuck Ebbert wrote:
> > On 01/22/2008 07:35 AM, Thomas Gleixner wrote:
> > > 
> > > That's a long standing bug in both the PI futex and the standard futex
> > > code. Needs to go to stable as well.
> > > 
> > 
> > Here's the 2.6.23 version:
> > 
> > 
> > Subject: x86: fix missing exception entry for SMP alternatives in futex macros
> > From: Thomas Gleixner <tglx@...utronix.de>
> 
> I don't see this in Linus's tree, am I just missing it?  Do you have a
> git commit id?

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=9d55b9923a1b7ea8193b8875c57ec940dc2ff027
 
I did a simpler version by just replacing LOCK_PREFIX with lock. The
reason is, that we would need a separate implementation for
__futex_atomic_op1() as well, due to:

case FUTEX_OP_ADD:
	__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,

And it's not really worth the trouble.

Backport to 2.6.24 and 2.6.23 attached.

Thanks,
	tglx
View attachment "futex-2-6-23.patch" of type "TEXT/PLAIN" (2973 bytes)

View attachment "futex-2-6-24.patch" of type "TEXT/PLAIN" (2913 bytes)