From: Andreas Schwab <schwab@suse.de>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Chuck Ebbert <76306.1226@compuserve.com>,
       linux-kernel <linux-kernel@vger.kernel.org>, Andi Kleen <ak@suse.de>,
       Andrew Morton <akpm@osdl.org>, Ingo Molnar <mingo@redhat.com>,
       Linus Torvalds <torvalds@osdl.org>
Subject: Re: set_bit() is broken on i386?
References: <200601201955_MC3-1-B649-DCF5@compuserve.com>
	<1137806107.8691.25.camel@lade.trondhjem.org>
Date: Sat, 21 Jan 2006 02:49:53 +0100
In-Reply-To: <1137806107.8691.25.camel@lade.trondhjem.org> (Trond Myklebust's
	message of "Fri, 20 Jan 2006 20:15:07 -0500")
Message-ID: <jek6cu73jy.fsf@sykes.suse.de>
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Trond Myklebust <trond.myklebust@fys.uio.no> writes:

> On Fri, 2006-01-20 at 19:53 -0500, Chuck Ebbert wrote:
>
>> #define ADDR (*(volatile long *) addr)
>> static inline void set_bit(int nr, volatile unsigned long * addr)
>> {
>> 	__asm__ __volatile__( "lock ; "
>> 		"btsl %1,%0"
>> 		:"=m" (ADDR)
>> 		:"Ir" (nr));
>> }
>
> The asm needs a memory clobber in order to avoid reordering with the
> assignment to b[1]:

Check out 2.6.16-rc1, this has already been fixed.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstra?e 5, 90409 N?rnberg, Germany
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