Re: [PATCH tip/core/rcu 07/13] rcu: Add smp_mb__after_atomic() to sync_exp_work_done()

[Peter Zijlstra]

On Wed, Apr 12, 2017 at 09:55:43AM -0700, Paul E. McKenney wrote:
> However, a little future-proofing is a good thing,
> especially given that smp_mb__before_atomic() is only required to
> provide acquire semantics rather than full ordering.  This commit
> therefore adds smp_mb__after_atomic() after the atomic_long_inc()
> in sync_exp_work_done().

Oh!? As far as I'm away the smp_mb__{before,after}_atomic() really must
provide full MB, no confusion about that.

We have other primitives for acquire/release.