162306a36Sopenharmony_ciC R+fencembonceonces
262306a36Sopenharmony_ci
362306a36Sopenharmony_ci(*
462306a36Sopenharmony_ci * Result: Never
562306a36Sopenharmony_ci *
662306a36Sopenharmony_ci * This is the fully ordered (via smp_mb()) version of one of the classic
762306a36Sopenharmony_ci * counterintuitive litmus tests that illustrates the effects of store
862306a36Sopenharmony_ci * propagation delays.  Note that weakening either of the barriers would
962306a36Sopenharmony_ci * cause the resulting test to be allowed.
1062306a36Sopenharmony_ci *)
1162306a36Sopenharmony_ci
1262306a36Sopenharmony_ci{}
1362306a36Sopenharmony_ci
1462306a36Sopenharmony_ciP0(int *x, int *y)
1562306a36Sopenharmony_ci{
1662306a36Sopenharmony_ci	WRITE_ONCE(*x, 1);
1762306a36Sopenharmony_ci	smp_mb();
1862306a36Sopenharmony_ci	WRITE_ONCE(*y, 1);
1962306a36Sopenharmony_ci}
2062306a36Sopenharmony_ci
2162306a36Sopenharmony_ciP1(int *x, int *y)
2262306a36Sopenharmony_ci{
2362306a36Sopenharmony_ci	int r0;
2462306a36Sopenharmony_ci
2562306a36Sopenharmony_ci	WRITE_ONCE(*y, 2);
2662306a36Sopenharmony_ci	smp_mb();
2762306a36Sopenharmony_ci	r0 = READ_ONCE(*x);
2862306a36Sopenharmony_ci}
2962306a36Sopenharmony_ci
3062306a36Sopenharmony_ciexists (y=2 /\ 1:r0=0)
31