__pthread_mutex_s
struct __pthread_mutex_s;
struct __pthread_mutex_s *dd_lock; /* lock */
pmutex = __malloc(sizeof(struct __pthread_mutex_s));
TAILQ_ENTRY(__pthread_mutex_s) m_qe;
TAILQ_HEAD(, __pthread_mutex_s) mutexq;
struct __pthread_mutex_s;
typedef struct __pthread_mutex_s *pthread_mutex_t;