pthread_mutex_reltimedlock_np() Syntax

int  pthread_mutex_reltimedlock_np(pthread_mutex_t *restrict mutex, 
          const struct timespec *restrict rel_timeout);

#include <pthread.h>
#include <time.h>

pthread_mutex_t mutex;
timestruct_t rel_timeout;
int ret;

ret = pthread_mutex_reltimedlock_np(&mutex,  &rel_timeout);