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From: Nick Piggin <npiggin@suse.de>
To: Scott Wood <scottwood@freescale.com>
Cc: linux-arch@vger.kernel.org, linuxppc-dev@ozlabs.org,
	Ingo Molnar <mingo@elte.hu>,
	paulus@samba.org
Subject: Re: [patch] powerpc: implement optimised mutex fastpaths
Date: Tue, 14 Oct 2008 09:06:22 +0200	[thread overview]
Message-ID: <20081014070621.GA2681@wotan.suse.de> (raw)
In-Reply-To: <20081013162020.GC19080@ld0162-tx32.am.freescale.net>

On Mon, Oct 13, 2008 at 11:20:20AM -0500, Scott Wood wrote:
> On Mon, Oct 13, 2008 at 11:15:47AM -0500, Scott Wood wrote:
> > On Sun, Oct 12, 2008 at 07:47:32AM +0200, Nick Piggin wrote:
> > > +static inline int __mutex_cmpxchg_lock(atomic_t *v, int old, int new)
> > > +{
> > > +	int t;
> > > +
> > > +	__asm__ __volatile__ (
> > > +"1:	lwarx	%0,0,%1		# mutex trylock\n\
> > > +	cmpw	0,%0,%2\n\
> > > +	bne-	2f\n"
> > > +	PPC405_ERR77(0,%1)
> > > +"	stwcx.	%3,0,%1\n\
> > > +	bne-	1b"
> > > +	ISYNC_ON_SMP
> > > +	"\n\
> > > +2:"
> > > +	: "=&r" (t)
> > > +	: "r" (&v->counter), "r" (old), "r" (new)
> > > +	: "cc", "memory");
> > 
> > This will break if the compiler picks r0 for &v->counter.  Use "b" as the
> > constraint, or better yet do "lwarx %0, %y1", with a "Z" (v->counter)
> > constraint.
> 
> Sorry, had a morning brain-fart there -- you're not using the base
> register.

OK no problem. Do you think it looks OK? Thanks for reviewing...

  reply	other threads:[~2008-10-14  7:06 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-12  5:46 [patch] mutex: optimise generic mutex implementations Nick Piggin
2008-10-12  5:47 ` [patch] powerpc: implement optimised mutex fastpaths Nick Piggin
2008-10-13  1:18   ` Nick Piggin
2008-11-06  4:09     ` Paul Mackerras
2008-11-06  5:06       ` Nick Piggin
2008-10-13 16:15   ` Scott Wood
2008-10-13 16:20     ` Scott Wood
2008-10-14  7:06       ` Nick Piggin [this message]
2008-10-14  8:35 ` [patch] mutex: optimise generic mutex implementations Benjamin Herrenschmidt
2008-10-22 15:59 ` Ingo Molnar
2008-10-23  4:43   ` Benjamin Herrenschmidt
2008-10-23  7:02     ` Nick Piggin
2008-10-22 16:24 ` David Howells

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