1
2 /* I don't think this is a very good test .. all this
3 sleepery is highly confusing. */
4
5 /* test child thread inheriting data */
6
7 #include <stdio.h>
8 #include <pthread.h>
9 #include <unistd.h>
10
11 static volatile int shared[2];
12
t1(void * v)13 static void *t1(void *v)
14 {
15 volatile int *ip = (int *)v;
16 if (0) printf("ta W\n");
17 *ip += 44;
18 *ip *= 2;
19 sleep(1);
20 return 0;
21 }
22
t2(void * v)23 static void *t2(void *v)
24 {
25 volatile int *ip = (int *)v;
26 sleep(2);
27 if (0) printf("tb W\n");
28 *ip += 88;
29 *ip *= 3;
30 sleep(1);
31 return 0;
32 }
33
main(void)34 int main(void)
35 {
36 pthread_t a, b;
37 volatile int ret = 0;
38
39 sleep(0);
40
41 shared[0] = 22;
42 shared[1] = 77;
43
44 pthread_create(&a, NULL, t1, (void *)&shared[0]);
45 // a steals shared[0] from root thread, so is excl(a)
46 pthread_create(&b, NULL, t2, (void *)&shared[1]);
47 // b steals shared[1] from root thread, so is excl(b)
48
49 pthread_join(a, NULL);
50 // b's stuff (shared[1]) still belongs to b, so is excl(b)
51
52 // ret is excl(root), and shared[0] is re-acquired as excl(root)
53 // since a joined to root
54 if (0) printf("r R1\n");
55 ret += shared[0]; /* no error - a is finished */
56
57 // but shared[1] is excl(b); hence we're reading excl(b)
58 // without a lock and without a dependency edge
59 if (0) printf("r R2\n");
60 ret += shared[1]; /* expect error - b has not finished,
61 so we can't touch shared[1] yet */
62
63 pthread_join(b, NULL);
64
65
66 return ret;
67 }
68