1/** Cause a race inside code protected by a reader lock.
2 */
3
4
5/* Needed for older glibc's (2.3 and older, at least) who don't
6   otherwise "know" about pthread_rwlock_anything or about
7   PTHREAD_MUTEX_RECURSIVE (amongst things). */
8
9#define _GNU_SOURCE 1
10
11#include <pthread.h>
12#include <stdio.h>
13#include <unistd.h>
14
15
16
17static pthread_rwlock_t s_rwlock;
18static int s_racy;
19
20static void sleep_ms(const int ms)
21{
22  struct timespec delay = { ms / 1000, (ms % 1000) * 1000 * 1000 };
23  nanosleep(&delay, 0);
24}
25
26static void* thread_func(void* arg)
27{
28  pthread_rwlock_rdlock(&s_rwlock);
29  s_racy++;
30  pthread_rwlock_unlock(&s_rwlock);
31  sleep_ms(100);
32  return 0;
33}
34
35int main(int argc, char** argv)
36{
37  pthread_t thread1;
38  pthread_t thread2;
39
40#if 0
41
42  VALGRIND_DO_CLIENT_REQUEST_STMT(VG_USERREQ__DRD_TRACE_ADDR,
43                                  &s_racy, 0, 0, 0, 0);
44#endif
45
46  pthread_rwlock_init(&s_rwlock, 0);
47  pthread_create(&thread1, 0, thread_func, 0);
48  pthread_create(&thread2, 0, thread_func, 0);
49  pthread_join(thread1, 0);
50  pthread_join(thread2, 0);
51  pthread_rwlock_destroy(&s_rwlock);
52
53  fprintf(stderr, "Result: %d\n", s_racy);
54
55  return 0;
56}
57