C S+fencewmbonceonce+poacquireonce (* * Result: Never * * Can a smp_wmb(), instead of a release, and an acquire order a prior * store against a subsequent store? *) {} P0(int *x, int *y) { WRITE_ONCE(*x, 2); smp_wmb(); WRITE_ONCE(*y, 1); } P1(int *x, int *y) { int r0; r0 = smp_load_acquire(y); WRITE_ONCE(*x, 1); } exists (x=2 /\ 1:r0=1)