[dm-devel] [PATCH 19/23] multipathd: move cleanup_{prio, checkers, foreign} to libmultipath_exit

[Martin Wilck]

On Mon, 2020-09-28 at 15:26 -0500, Benjamin Marzinski wrote:
> On Thu, Sep 24, 2020 at 03:40:50PM +0200, mwilck at suse.com wrote:
> > 
> >  /*
> >   * We don't support re-initialization after
> > @@ -65,6 +66,9 @@ int libmultipath_init(void)
> >  static void _libmultipath_exit(void)
> >  {
> >  	libmultipath_exit_called = true;
> > +	cleanup_foreign();
> 
> I don't really feel too strongly about this, but it seems to me that
> there is a difference between the checkers and prioritizers, which
> it seems like most users of libmultipath would want, and the foreign
> code, which doesn't seem that way. libmpathpersist, for instance,
> will use the checkers and prioritizers, but not the foreign code.
> On the other hand, if the caller isn't using the foreign code,
> then grabbing the lock and checking the foreign pointer shouldn't
> take much time.

It would just be a few cycles. I want callers to have to worry about
cleanup as little as possible. All else is error-prone IMO, and
although I agree that the foreign functions are less important than
checkers and prio, I thought it made sense to treat all our "plug-ins"
the same way.

Ideally I'd like to do checker/prio/foreign initialization completely
lazily too, in the sense that callers don't need to worry about calling
init_checkers() etc., either. But this series had to stop at some
point.

Either way, it's not a big issue, so please tell me if you feel
strongly enough about it to ask me to revert the change.

Regards,
Martin