41 lines
658 B
Plaintext
41 lines
658 B
Plaintext
C Z6.0+pooncelock+pooncelock+pombonce
|
|
|
|
(*
|
|
* Result: Sometimes
|
|
*
|
|
* This example demonstrates that a pair of accesses made by different
|
|
* processes each while holding a given lock will not necessarily be
|
|
* seen as ordered by a third process not holding that lock.
|
|
*)
|
|
|
|
{}
|
|
|
|
P0(int *x, int *y, spinlock_t *mylock)
|
|
{
|
|
spin_lock(mylock);
|
|
WRITE_ONCE(*x, 1);
|
|
WRITE_ONCE(*y, 1);
|
|
spin_unlock(mylock);
|
|
}
|
|
|
|
P1(int *y, int *z, spinlock_t *mylock)
|
|
{
|
|
int r0;
|
|
|
|
spin_lock(mylock);
|
|
r0 = READ_ONCE(*y);
|
|
WRITE_ONCE(*z, 1);
|
|
spin_unlock(mylock);
|
|
}
|
|
|
|
P2(int *x, int *z)
|
|
{
|
|
int r1;
|
|
|
|
WRITE_ONCE(*z, 2);
|
|
smp_mb();
|
|
r1 = READ_ONCE(*x);
|
|
}
|
|
|
|
exists (1:r0=1 /\ z=2 /\ 2:r1=0)
|