Re: [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends()

[Paul E. McKenney]

On Wed, Oct 11, 2017 at 01:21:03PM +0100, David Howells wrote:
> Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> 
> > Will Deacon has proposed adding smp_read_barrier_depends() to READ_ONCE(),
> > which would mean that quite a few instances of smp_read_barrier_depends()
> > would become redundant.
> 
> It's not clear from you description where the barrier is added in relation to
> the read: before, after or both?

After, similar to lockless_dereference().  Of course, there is not
really a barrier except for on Alpha.

							Thanx, Paul