162306a36Sopenharmony_ciC MP+fencewmbonceonce+fencermbonceonce
262306a36Sopenharmony_ci
362306a36Sopenharmony_ci(*
462306a36Sopenharmony_ci * Result: Never
562306a36Sopenharmony_ci *
662306a36Sopenharmony_ci * This litmus test demonstrates that smp_wmb() and smp_rmb() provide
762306a36Sopenharmony_ci * sufficient ordering for the message-passing pattern.  However, it
862306a36Sopenharmony_ci * is usually better to use smp_store_release() and smp_load_acquire().
962306a36Sopenharmony_ci *)
1062306a36Sopenharmony_ci
1162306a36Sopenharmony_ci{}
1262306a36Sopenharmony_ci
1362306a36Sopenharmony_ciP0(int *buf, int *flag) // Producer
1462306a36Sopenharmony_ci{
1562306a36Sopenharmony_ci	WRITE_ONCE(*buf, 1);
1662306a36Sopenharmony_ci	smp_wmb();
1762306a36Sopenharmony_ci	WRITE_ONCE(*flag, 1);
1862306a36Sopenharmony_ci}
1962306a36Sopenharmony_ci
2062306a36Sopenharmony_ciP1(int *buf, int *flag) // Consumer
2162306a36Sopenharmony_ci{
2262306a36Sopenharmony_ci	int r0;
2362306a36Sopenharmony_ci	int r1;
2462306a36Sopenharmony_ci
2562306a36Sopenharmony_ci	r0 = READ_ONCE(*flag);
2662306a36Sopenharmony_ci	smp_rmb();
2762306a36Sopenharmony_ci	r1 = READ_ONCE(*buf);
2862306a36Sopenharmony_ci}
2962306a36Sopenharmony_ci
3062306a36Sopenharmony_ciexists (1:r0=1 /\ 1:r1=0) (* Bad outcome. *)
31