Re: RFC: localcount_hadref() or localcount_trydarin()

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

> Date: Fri, 9 Jun 2017 16:50:18 +0900
> From: Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>
> 
> I tried using localcount(9) for opencyrpto(9) to avoid detach encryption
> drivers. While I implement that, I want to something to use KASSERT which
> ensure someone have reference or not.
> In addition, localcount_drain() waits forever if someone has had reference.
> So, I want to function which returns in not so long time regardless of
> someone has reference or not. In other words, I want some function like
> mutex_tryenter() for mutex_enter().

This sounds questionable to me.  If there is a reference remaining
that does not drain in a bounded time, that sounds like a bug that
should be addressed some other way.  Can you explain how you want to
use this?  Can you share preliminary diffs to opencrypto code with
localcount that motivate this?