1#include <stdio.h> 2#include <pthread.h> 3 4pthread_mutex_t a = PTHREAD_MUTEX_INITIALIZER; 5pthread_mutex_t b = PTHREAD_MUTEX_INITIALIZER; 6pthread_barrier_t bar; 7 8void *ba_lock(void *arg) 9{ 10 int ret, i; 11 12 pthread_mutex_lock(&b); 13 14 if (pthread_barrier_wait(&bar) == PTHREAD_BARRIER_SERIAL_THREAD) 15 pthread_barrier_destroy(&bar); 16 17 pthread_mutex_lock(&a); 18 19 pthread_mutex_unlock(&a); 20 pthread_mutex_unlock(&b); 21} 22 23int main(void) 24{ 25 pthread_t t; 26 27 pthread_barrier_init(&bar, NULL, 2); 28 29 if (pthread_create(&t, NULL, ba_lock, NULL)) { 30 fprintf(stderr, "pthread_create() failed\n"); 31 return 1; 32 } 33 pthread_mutex_lock(&a); 34 35 if (pthread_barrier_wait(&bar) == PTHREAD_BARRIER_SERIAL_THREAD) 36 pthread_barrier_destroy(&bar); 37 38 pthread_mutex_lock(&b); 39 40 pthread_mutex_unlock(&b); 41 pthread_mutex_unlock(&a); 42 43 pthread_join(t, NULL); 44 45 return 0; 46} 47