/* TAGS: c threads */ /* Testcase from Threader's distribution. For details see: http://www.model.in.tum.de/~popeea/research/threader */ #include #include int flag1 = 0, flag2 = 0; // boolean flags int turn; // integer variable to hold the ID of the thread whose turn is it int x; // boolean variable to test mutual exclusion void *thr1(void *arg) { flag1 = 1; while (flag2 >= 1) { if (turn != 0) { flag1 = 0; while (turn != 0) {}; flag1 = 1; } } // begin: critical section x = 0; assert(x<=0); // end: critical section turn = 1; flag1 = 0; return 0; } void *thr2(void *arg) { flag2 = 1; while (flag1 >= 1) { if (turn != 1) { flag2 = 0; while (turn != 1) {}; flag2 = 1; } } // begin: critical section x = 1; assert(x>=1); // end: critical section turn = 1; flag2 = 0; return 0; } int main() { pthread_t t1, t2; turn = __vm_choose(2); pthread_create(&t1, 0, thr1, 0); pthread_create(&t2, 0, thr2, 0); pthread_join(t1, 0); pthread_join(t2, 0); return 0; }