| C MP+fencewmbonceonce+fencermbonceonce |
| |
| (* |
| * Result: Never |
| * |
| * This litmus test demonstrates that smp_wmb() and smp_rmb() provide |
| * sufficient ordering for the message-passing pattern. However, it |
| * is usually better to use smp_store_release() and smp_load_acquire(). |
| *) |
| |
| {} |
| |
| P0(int *buf, int *flag) // Producer |
| { |
| WRITE_ONCE(*buf, 1); |
| smp_wmb(); |
| WRITE_ONCE(*flag, 1); |
| } |
| |
| P1(int *buf, int *flag) // Consumer |
| { |
| int r0; |
| int r1; |
| |
| r0 = READ_ONCE(*flag); |
| smp_rmb(); |
| r1 = READ_ONCE(*buf); |
| } |
| |
| exists (1:r0=1 /\ 1:r1=0) (* Bad outcome. *) |
