Re: [PATCH v2 2/3] mutex: add support for reservation style locks, v2

Peter Zijlstra
2013-04-04T16:46:10Z

On Thu, 2013-04-04 at 15:31 +0200, Daniel Vetter wrote:
> I'm a bit confused about the different classes you're talking about.
> Since
> the ticket queue is currently a global counter there's only one class
> of
> ww_mutexes.

Right, so that's not something that's going to fly.. we need to support
multiple users, including nesting of those. Again, you're adding
something to the generic kernel infrastructure, it had better be usable
:-)

> I guess we could change that once a second user shows up

No, we fix that before it all goes in. I would _so_ hate to find out it
cannot be 'fixed' and be stuck with a half-arsed sync primitive in the
core kernel that's only every usable by the one existent user.

So for now, forget all about TTM, DMA-BUF and other such coolness
except to verify that whatever we end up with does indeed work for the
case you need it for ;-)