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Message-ID: <alpine.LFD.2.01.0909301320300.6996@localhost.localdomain>
Date: Wed, 30 Sep 2009 13:20:58 -0700 (PDT)
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Eric Dumazet <eric.dumazet@...il.com>
cc: Ingo Molnar <mingo@...e.hu>,
Arjan van de Ven <arjan@...radead.org>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Thomas Gleixner <tglx@...utronix.de>,
John Stultz <johnstul@...ibm.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: Linux 2.6.32-rc1
On Wed, 30 Sep 2009, Eric Dumazet wrote:
> > +#define cmpxchg64(ptr, o, n) \
> > +({ \
> > + __typeof__(*(ptr)) __ret; \
> > + __typeof__(*(ptr)) __old = (o); \
> > + __typeof__(*(ptr)) __new = (n); \
> > + alternative_io("call cmpxchg8b_emu", \
> > + "lock; cmpxchg8b (%%esi)" , \
> > + X86_FEATURE_CX8, \
> > + "=A" (__ret), \
> > + "S" ((ptr)), "0" (__old), \
> > + "b" ((unsigned int)__new), \
> > + "c" ((unsigned int)(__new>>32))); \
>
> probably a "memory" clobber is needed, alternative_io() doesnt provide it.
Yeah, good catch.
Linus
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