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SubjectRE: Bitops source problem
Date
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Yes, indeed none of the atomic bit operations functions has LOCK_PREFIX in my version of Linux kernel.

Regards,
Pravin


-----Original Message-----
From: linux-kernel-owner@vger.kernel.org
[mailto:linux-kernel-owner@vger.kernel.org]On Behalf Of Roland Dreier
Sent: Thursday, January 17, 2008 12:15 PM
To: Pravin Nanaware
Cc: John Hubbard; LKML
Subject: Re: Bitops source problem


> Then, I think there is a problem with the function written below which is meant to be atomic.
>
> static __inline__ void change_bit(int nr, volatile void * addr)
> {
> __asm__ __volatile__(
> "btcl %1,%0"
> :"=m" (ADDR)
> :"Ir" (nr));
> }

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));
}

- R.


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