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 17 static pthread_rwlock_t s_rwlock; 18 static int s_racy; 19 20 static void sleep_ms(const int ms) 21 { 22 struct timespec delay = { ms / 1000, (ms % 1000) * 1000 * 1000 }; 23 nanosleep(&delay, 0); 24 } 25 26 static 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 35 int 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
