sewardj | b411202 | 2007-11-09 22:49:28 +0000 | [diff] [blame] | 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 | |
| 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 | |
| 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 | |
| 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 | } |