LXR linux/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus

   1C SB+fencembonceonces
   2
   3(*
   4 * Result: Never
   5 *
   6 * This litmus test demonstrates that full memory barriers suffice to
   7 * order the store-buffering pattern, where each process writes to the
   8 * variable that the preceding process reads.  (Locking and RCU can also
   9 * suffice, but not much else.)
  10 *)
  11
  12{}
  13
  14P0(int *x, int *y)
  15{
  16        int r0;
  17
  18        WRITE_ONCE(*x, 1);
  19        smp_mb();
  20        r0 = READ_ONCE(*y);
  21}
  22
  23P1(int *x, int *y)
  24{
  25        int r0;
  26
  27        WRITE_ONCE(*y, 1);
  28        smp_mb();
  29        r0 = READ_ONCE(*x);
  30}
  31
  32exists (0:r0=0 /\ 1:r0=0)
  33