[ Added linux-arch ]
On Mon, 2010-02-01 at 17:29 +0100, Peter Zijlstra wrote:
> On Mon, 2010-02-01 at 11:24 -0500, Steven Rostedt wrote:
> >
> > Doesn't set_bit imply a wmb()? If so couldn't we do:
>
> Nope, that's what we have smp_mb__{before,after}_set_bit() for.
>
> On x86 its a LOCK'ed op, so sure it implies a full membarrier, but not
> in generic.
>
> on x86 we have plenty serializing instructions before and after rq->curr
> is set so none of the crazyness is needed at all. The only thing is !
> x86.
>
So if we go with Linus's approach and make all archs guarantee that
switch_mm() implies a full mb(), then we can simplify the
sys_membarrier() code?
That looks like the best approach.
-- Steve
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