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

Herbert Xu
2005-03-23T09:51:05Z

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,
--
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt