From: Andi Kleen <ak@muc.de>
To: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: vojtech@suse.cz, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] atomic_cmpxchg return type error
Date: 1 Dec 2006 00:23:54 +0100
Date: Fri, 1 Dec 2006 00:23:54 +0100 [thread overview]
Message-ID: <20061130232354.GA12359@muc.de> (raw)
In-Reply-To: <20061130211705.GA12987@Krystal>
On Thu, Nov 30, 2006 at 04:17:06PM -0500, Mathieu Desnoyers wrote:
> Hi,
>
> I just noticed that a atomic_cmpxchg, that would be given an atomic64_t
> parameter, would cast the return value as a (int). In the typical use of this
> primitive, the result would be that the 32 MSB would be lost when comparing
> against the original value. It also affects atomic_add_unless. Note that there
> is no atomic64_cmpxchg nor atomic64_add_unless, which might make things a
> little clearer.
Normally you're supposed to only use atomic64_* with atomic64_t
While it works for most by accident on x86 to just use atomic_*
with atomic64_t it's not portable to other architectures.
If you want to use those with atomic64_t suitable macros would need
to be added on all architectures.
-Andi
prev parent reply other threads:[~2006-11-30 23:23 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-30 21:17 [PATCH] atomic_cmpxchg return type error Mathieu Desnoyers
2006-11-30 23:23 ` Andi Kleen [this message]
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