Re: XDP socket rings, and LKMM litmus tests

Björn Töpel
2021-03-02T22:37:53Z

On Tue, 2 Mar 2021 at 21:04, Paul E. McKenney <paulmck@kernel.org> wrote:
>

[...]

>
> And if the answer is "yes", how about this one?
>

With the == to != change in P1, this is OK!

> P0(int *prod, int *cons, int *data)
> {
> int p;
>
> p = READ_ONCE(*prod);
> if (p == READ_ONCE(*cons)) {

...and now d==1 is not a valid state anymore according to herd. If
think I need some input here! :-D

> WRITE_ONCE(*data, 1);
> smp_wmb();
> WRITE_ONCE(*prod, p ^ 1);
> }
> }
>
> P1(int *prod, int *cons, int *data)
> {
> int c;
> int d = -1;
>
> c = READ_ONCE(*cons);
> if (READ_ONCE(*prod) == c) {
> smp_rmb();
> d = READ_ONCE(*data);
> smp_mb();
> WRITE_ONCE(*cons, c ^ 1);
> }
> }
>

[...]

Björn