;return res;
}
PTHREAD_TRACE(psynch_mutex_kwqwait, kwq->kw_addr, kwq->kw_inqueue,
kwq->kw_prepost.count, kwq->kw_intr.count);
if (_kwq_use_turnstile(kwq)) {
// pthread mutexes and rwlocks both (at least sometimes) know their
// owner and can use turnstiles. Otherwise, we pass NULL as the
// tstore to the shims so they wait on the global waitq.
tstore = &kwq->kw_turnstile;
}
......
}
再去查看_kwq_use_turnstile的定义，代码还是很诚实的，只有在KSYN_WQTYPE_MTX才会启用turnstile进行优先级反转保护，而读写锁的类型为KSYN_WQTYPE_RWLOCK，这说明读写锁不会使用_kwq_use_turnstile，所以无法避免优先级反转。
#define KSYN_WQTYPE_MTX 0x01
#define KSYN_WQTYPE_CVAR 0x02
#define KSYN_WQTYPE_RWLOCK 0x04
#define KSYN_WQTYPE_SEMA 0x08
static inline bool
_kwq_use_turnstile(ksyn_wait_queue_t kwq)
{
// If we had writer-owner information from the
// rwlock then we could use the turnstile to push on it. For now, only
// plain mutexes use it.
return (_kwq_type(kwq) == KSYN_WQTYPE_MTX);
}
另外在_pthread_find_owner也可以看到，读写锁的owner是0
void
_pthread_find_owner(thread_t thread,
struct stackshot_thread_waitinfo * waitinfo)
{