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) |