linux-kernel - blackfin - cmpxchg not atomic ?

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Message-ID: <20070720202807.GA15009@Krystal>
Date:	Fri, 20 Jul 2007 16:28:08 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	tonyko@...eo.ca, robin.getz@...log.com
Cc:	linux-kernel@...r.kernel.org
Subject: blackfin - cmpxchg not atomic ?

Hello,

I am currently passing through each architectures adding a
cmpxchg_local() to each system.h, and I notice that you disable
interrupts in your cmpxchg() implementation, why are you doing so ?
Also, does you assembly stub _really_ modify memory atomically ? If yes,
then there should be no need for disabling interrupts. Else, I see a
major problem with SMP.

I also don't like the comment in asm-blackfin/atomic.h :

 * Generally we do not concern about SMP BFIN systems, so we don't have
 * to deal with that.

I have seen on the blackfin website that you actually sell a board with
SMP. Why aren't you caring about it ?

Mathieu

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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