Re: [RFC][PATCH -v2 1/4] locking/drm/i915: Kill mutex trickery

[Waiman Long]

On 08/25/2016 03:36 PM, Daniel Vetter wrote:
> On Thu, Aug 25, 2016 at 8:37 PM, Peter Zijlstra<peterz@xxxxxxxxxxxxx>  wrote:
> > Poking at lock internals is not cool. Since I'm going to change the
> > implementation this will break, take it out.
> >
> > Cc: Chris Wilson<chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Daniel Vetter<daniel.vetter@xxxxxxxx>
> > Signed-off-by: Peter Zijlstra (Intel)<peterz@xxxxxxxxxxxxx>
> It's horrible, but we die without this in spurious oom. And we haven't
> made much progress in recent years to throw out the locking scheme and
> replace it by something else that doesn't need a recursive mutex.
>
> But initerim I guess we could set our own owner field and check that
> to keep the duct-tape from getting off completely.
> -Daniel

Another alternative is to provide a standard mutex API that returns the 
owner of the lock if there is a real need for this capability. Peeking 
into lock internal is not a good practice.

Cheers,
Longman