互斥锁与条件变量实现读写锁----my_pthread_rwlock_destroy

#include "../unipc.h"
#include "pthread_rwlock.h"


int my_pthread_rwlock_destroy(my_pthread_rwlock_t * rw)
{
    if(rw->rw_magic != RW_MAGIC)
        return EINVAL;

    if(rw->rw_nwaitreaders != 0
      || rw->rw_nwaitwriters != 0
      || rw->rw_refcount != 0)
        return EBUSY;
    pthread_mutex_destroy(&rw->rw_mutex);

    pthread_cond_destroy(&rw->rw_condreaders);
    pthread_cond_destroy(&rw->rw_condwriters);

    rw->rw_magic = 0;
    return 0;
}