Re: [PATCH RFD] alternative kobject release wait mechanism

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Fri, 20 Apr 2007 14:27:06 +0900,
Tejun Heo <htejun@gmail.com> wrote:

> Hello, Alan.
> 
> Alan Stern wrote:
> > This doesn't solve a related problem: a subsystem wants to register
> > devices and to provide a set of mutually-exclusive services to the
> > devices' drivers.  The mutual exclusion has to be provided by a mutex or
> > something similar, and the drivers need a way to unbind even while waiting
> > to acquire the mutex.
> 
> I don't really follow why the drivers need a way to unbind even while
> waiting to acquire the mutex.  Care to enlighten me?

I guess when the driver is just being ripped out or an unbind has been
triggered or similar.

> Yeah, exactly.  My argument is that that impedance matching between
> lifetime rules must happen at some place and it's better if we can do in
> the higher layer where we can afford more effort and thus complexity.
> We're currently pushing that down to each drivers and not too many are
> getting it right.  I think it's just unrealistic to expect every and
> each driver subsystems to get it right, so some overhead at higher layer
> is acceptable and we can definitely afford much more optimization at
> higher layer.

I agree. It isn't easy to get this right, so just we should just solve
that once for all drivers.