Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus

   1 C Atomic-RMW+mb__after_atomic-is-stronger-than-acquire
   2
   3 (*
   4  * Result: Never
   5  *
   6  * Test that an atomic RMW followed by a smp_mb__after_atomic() is
   7  * stronger than a normal acquire: both the read and write parts of
   8  * the RMW are ordered before the subsequential memory accesses.
   9  *)
  10
  11 {
  12 }
  13
  14 P0(int *x, atomic_t *y)
  15 {
  16         int r0;
  17         int r1;
  18
  19         r0 = READ_ONCE(*x);
  20         smp_rmb();
  21         r1 = atomic_read(y);
  22 }
  23
  24 P1(int *x, atomic_t *y)
  25 {
  26         atomic_inc(y);
  27         smp_mb__after_atomic();
  28         WRITE_ONCE(*x, 1);
  29 }
  30
  31 exists
  32 (0:r0=1 /\ 0:r1=0)