c 递归锁(重入锁) pthread_cond_wait 死锁

//1 thread

pthread_mutex_lock(&mutex);

pthread_mutex_lock(&mutex);

pthread_cond_wait(&cond, &mutex);

pthread_mutex_unlock(&mutex);

pthread_mutex_unlock(&mutex);

//2 thread

pthread_mutex_lock(&mutex);

pthread_cond_signal(&mutex);

pthread_mutex_unlock(&mutex);

//3 init

pthread_mutexattr_t attr;

pthread_mutexattr_init(&attr);

pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);

pthread_mutex_init(&mutex, &attr);

先执行1 thread,然后执行2 thread,会发现在锁定1 thread后，进行pthread_cond_wait操作后，会导致死锁

猜想，应该是pthread_cond_wait只会解锁一层mutex,最后还有一层锁定状态，导致死锁状态

另还有文档说明不要使用pthread_cond_wait在递归锁(重入锁)中