tools/memory-model/litmus-tests/Z6.0+pooncelock+poonceLock+pombonce.litmus

   1 C Z6.0+pooncelock+poonceLock+pombonce
   2
   3 (*
   4  * Result: Never
   5  *
   6  * This litmus test demonstrates how smp_mb__after_spinlock() may be
   7  * used to ensure that accesses in different critical sections for a
   8  * given lock running on different CPUs are nevertheless seen in order
   9  * by CPUs not holding that lock.
  10  *)
  11
  12 {}
  13
  14 P0(int *x, int *y, spinlock_t *mylock)
  15 {
  16         spin_lock(mylock);
  17         WRITE_ONCE(*x, 1);
  18         WRITE_ONCE(*y, 1);
  19         spin_unlock(mylock);
  20 }
  21
  22 P1(int *y, int *z, spinlock_t *mylock)
  23 {
  24         int r0;
  25
  26         spin_lock(mylock);
  27         smp_mb__after_spinlock();
  28         r0 = READ_ONCE(*y);
  29         WRITE_ONCE(*z, 1);
  30         spin_unlock(mylock);
  31 }
  32
  33 P2(int *x, int *z)
  34 {
  35         int r1;
  36
  37         WRITE_ONCE(*z, 2);
  38         smp_mb();
  39         r1 = READ_ONCE(*x);
  40 }
  41
  42 exists (1:r0=1 /\ z=2 /\ 2:r1=0)