1#include <pthread.h>
2#include <stdio.h>
3#include <stddef.h>
4#include <unistd.h>
5
6pthread_mutex_t Mtx;
7int Global;
8
9void *Thread1(void *x) {
10  pthread_mutex_init(&Mtx, 0);
11  pthread_mutex_lock(&Mtx);
12  Global = 42;
13  pthread_mutex_unlock(&Mtx);
14  return NULL;
15}
16
17void *Thread2(void *x) {
18  usleep(1000000);
19  pthread_mutex_lock(&Mtx);
20  Global = 43;
21  pthread_mutex_unlock(&Mtx);
22  return NULL;
23}
24
25int main() {
26  pthread_t t[2];
27  pthread_create(&t[0], NULL, Thread1, NULL);
28  pthread_create(&t[1], NULL, Thread2, NULL);
29  pthread_join(t[0], NULL);
30  pthread_join(t[1], NULL);
31  pthread_mutex_destroy(&Mtx);
32  return 0;
33}
34
35// CHECK:      WARNING: ThreadSanitizer: data race
36// CHECK-NEXT:   Read of size 1 at {{.*}} by thread 2:
37// CHECK-NEXT:     #0 pthread_mutex_lock
38// CHECK-NEXT:     #1 Thread2{{.*}} {{.*}}race_on_mutex.c:19{{(:3)?}} ({{.*}})
39// CHECK:        Previous write of size 1 at {{.*}} by thread 1:
40// CHECK-NEXT:     #0 pthread_mutex_init {{.*}} ({{.*}})
41// CHECK-NEXT:     #1 Thread1{{.*}} {{.*}}race_on_mutex.c:10{{(:3)?}} ({{.*}})
42