Re: [patch] Real-Time Preemption, -RT-2.6.12-rc1-V0.7.41-07

[Herbert Xu]

On Wed, Mar 23, 2005 at 08:38:11PM +1100, Herbert Xu wrote:
>
> > ok. It's enough to put a barrier into the else branch here, because the
> > atomic op in the main brain is a barrier by itself.
> 
> Since the else branch is only taken when rcu_read_lock_nesting > 0, do
> we need the barrier at all?

Actually, since atomic_inc isn't a barrier, we do need that mb.
However, it should only be necessary in the main branch and we
can use smp_mb__after_atomic_inc which is optimised away on a
number of architectures (i386 in particular).

Cheers,
-- 
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