From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Chuck Ebbert <76306.1226@compuserve.com>
Cc: 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?
Date: Fri, 20 Jan 2006 20:15:07 -0500 [thread overview]
Message-ID: <1137806107.8691.25.camel@lade.trondhjem.org> (raw)
In-Reply-To: <200601201955_MC3-1-B649-DCF5@compuserve.com>
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]:
static inline void set_bit(int nr, volatile unsigned long * addr)
{
__asm__ __volatile__( "lock ; "
"btsl %1,%0"
:"=m" (ADDR)
:"Ir" (nr)
: "memory");
}
This works consistently correctly for me.
Cheers,
Trond
next prev parent reply other threads:[~2006-01-21 1:15 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-21 0:53 Chuck Ebbert
2006-01-21 1:15 ` Trond Myklebust [this message]
2006-01-21 1:49 ` Andreas Schwab
2006-01-21 2:38 ` Andrew Morton
2006-01-21 19:26 ` Trond Myklebust
2006-01-21 1:32 ` Valdis.Kletnieks
2006-01-21 2:01 ` Grzegorz Kulewski
2006-01-21 1:48 ` Andrew Morton
2006-01-21 1:38 Kenny Simpson
2006-01-21 1:46 Kenny Simpson
2006-01-21 2:07 Kenny Simpson
2006-01-21 7:43 Chuck Ebbert
2006-01-21 20:49 Chuck Ebbert
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