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
| C RCU+sync+read
|
| (*
| * Result: Never
| *
| * This litmus test demonstrates that after a grace period, an RCU updater always
| * sees all stores done in prior RCU read-side critical sections. Such
| * read-side critical sections would have ended before the grace period ended.
| *
| * This is one implication of the RCU grace-period guarantee, which says (among
| * other things) that an RCU read-side critical section cannot span a grace period.
| *)
|
| {
| int x = 0;
| int y = 0;
| }
|
| P0(int *x, int *y)
| {
| rcu_read_lock();
| WRITE_ONCE(*x, 1);
| WRITE_ONCE(*y, 1);
| rcu_read_unlock();
| }
|
| P1(int *x, int *y)
| {
| int r0;
| int r1;
|
| r0 = READ_ONCE(*x);
| synchronize_rcu();
| r1 = READ_ONCE(*y);
| }
|
| exists (1:r0=1 /\ 1:r1=0)
|
|
