On Tue, Oct 10, 2017 at 01:50:39PM +0100, Mark Rutland wrote:
> On Tue, Oct 10, 2017 at 05:47:12AM -0700, Paul E. McKenney wrote:
> > On Tue, Oct 10, 2017 at 10:54:14AM +0100, Mark Rutland wrote:
> > > On Mon, Oct 09, 2017 at 12:51:12PM -0700, Paul E. McKenney wrote:
> > > > On Mon, Oct 09, 2017 at 07:28:50PM +0100, Mark Rutland wrote:
> > > > > diff --git
> > > > > a/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/barriers.h
> > > > > b/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/barriers.h
> > > > > index 6687acc..ee4e4f8 100644
> > > > > ---
> > > > > a/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/barriers.h
> > > > > +++
> > > > > b/tools/testing/selftests/rcutorture/formal/srcu-cbmc/src/barriers.h
> > > > > @@ -34,8 +34,9 @@
> > > > > #define rs_smp_mb() do {} while (0)
> > > > > #endif
> > > > >
> > > > > -#define ACCESS_ONCE(x) (*(volatile typeof(x) *) &(x))
> > > > > -#define READ_ONCE(x) ACCESS_ONCE(x)
> > > > > -#define WRITE_ONCE(x, val) (ACCESS_ONCE(x) = (val))
> > > > > +#define __ACCESS_ONCE(x) (*(volatile typeof(x) *) &(x))
> > > > > +#define ACCESS_ONCE(x) __ACCESS_ONCE(x)
> > > > > +#define READ_ONCE(x) __ACCESS_ONCE(x)
> > > > > +#define WRITE_ONCE(x, val) (__ACCESS_ONCE(x) = (val))
> > > >
> > > > How about something like the following?
> > > >
> > > > #define READ_ONCE(x) (*(volatile typeof(x) *) &(x))
> > > > #define WRITE_ONCE(x) ((*(volatile typeof(x) *) &(x)) = (val))
> > >
> > > Sure; folded in and pushed out. :)
> >
> > Thank you!
> >
> > > I've assumed that the ACCESS_ONCE() definition needs to be kept until
> > > that's ripped out treewide. Please shout if that's not the case!
> >
> > You have it right. This case is an exception because this code is
> > used only by RCU, which has long since had ACCESS_ONCE() ripped out.
>
> Sorry; I meant that in this case, I leave this code as:
>
> #define ACCESS_ONCE(x) (*(volatile typeof(x) *) &(x))
> #define READ_ONCE(x) (*(volatile typeof(x) *) &(x))
> #define WRITE_ONCE(x) ((*(volatile typeof(x) *) &(x)) = (val))
>
> ... if you mean that we can drop ACCESS_ONCE() in this case, then I can
> rip that out.
We can drop ACCESS_ONCE() in this case.
Thanx, Paul
