Re: [PATCH [RT] 05/14] rearrange rt_spin_lock sleep

From: Ingo Molnar
Date: Fri Feb 22 2008 - 08:36:23 EST



* Gregory Haskins <gregory.haskins.ml@xxxxxxxxx> wrote:

> My assumption is that the xchg() (inside update_current()) acts as an
> effective wmb(). If xchg() does not have this property, then this
> code is broken and patch 6/14 should also add a:

xchg() is a strong implicit memory barrier, it implies smp_mb().
(historic sidenote: it was the very first SMP primitive we had in
Linux.)

Ingo
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