[Nouveau] [PATCH 1/3] drm/nouveau: fix vblank interrupt being called before event is setup

[Maarten Lankhorst]

Op 30-07-13 04:42, Ben Skeggs schreef:
> On Tue, Jul 23, 2013 at 11:43 PM, Maarten Lankhorst
> <maarten.lankhorst at canonical.com> wrote:
>> Sort of fixes mmiotrace for me again, I could sear I sent a similar patch before
>> the rework to event interface, so I guess it got reintroduced.
> I don't know how/why you think this fixes anything.  The interrupt
> handler can't possibly be called until after priv->base.vblank has
> been initialised...
>
> Seriously, go look, the subdev interrupt handler pointer isn't filled
> in (and can't be) until after nouveau_disp_create() has been called,
> and nouveau_disp_create() initialises priv->base.vblank before it
> returns...
>
There's also a disp_dtor function right above it and without a smp_wmb
the writes could still be reordered in the constructor. O:-) A spinlock would
be needed to make sure that no interrupt is in process if you set intr to null
before destroying vblank event, though.

I can probably try to get the oops again indicating that priv->base.vblank was null in the interrupt handler if you want,
iirc it happened reliably during mmiotracing.

~Maarten