Date: Thu, 17 Jan 2008 15:59:24 +0900
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Roland Dreier <rdreier@cisco.com>
Subject: Re: Bitops source problem
Cc: kosaki.motohiro@jp.fujitsu.com,
       "Pravin Nanaware" <p.nanaware@nihilent.com>,
       "John Hubbard" <john.hubbard@gmail.com>,
       "LKML" <linux-kernel@vger.kernel.org>
In-Reply-To: <adamyr5x86k.fsf@cisco.com>
References: <1145971D427D7F43B0DBDAE22221C4B502CCE22D@nipns00a210.FPS.NIHILENT.COM> <adamyr5x86k.fsf@cisco.com>
Message-Id: <20080117155723.11DC.KOSAKI.MOTOHIRO@jp.fujitsu.com>
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Hi

> If that is indeed the source of your change_bit function then there is
> a problem.  However in my kernel tree there is a LOCK_PREFIX in the
> definition of the atomic version.  I don't have your exact source tree
> handy, but on a local RHEL4 system, the LOCK_PREFIX is still there:
> 
> static inline void change_bit(int nr, volatile unsigned long * addr)
> {
>         __asm__ __volatile__( LOCK_PREFIX
>                 "btcl %1,%0"
>                 :"=m" (ADDR)
>                 :"Ir" (nr));
> }

2.6.24-rc6-mm1 have LOCK_PREFIX too :)


static inline void change_bit(int nr, volatile void *addr)
{
        asm volatile(LOCK_PREFIX "btc %1,%0"
                     : ADDR : "Ir" (nr));
}

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