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

   1C 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
  14P0(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
  22P1(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
  33P2(int *x, int *z)
  34{
  35        int r1;
  36
  37        WRITE_ONCE(*z, 2);
  38        smp_mb();
  39        r1 = READ_ONCE(*x);
  40}
  41
  42exists (1:r0=1 /\ z=2 /\ 2:r1=0)
  43