1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
| 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)
|
|
