Warnings in DRM code when removing/unbinding a driver

[Gerd Hoffmann]

  Hi,

> >   Like I said, for most drivers
> > > you can pretty much assume that their unload sequence has been broken
> > > since forever. It's not often tested, and especially the hotunbind
> > > from a device (as opposed to driver unload) stuff wasn't even possible
> > > to get right until just recently.
> >
> > Do you think it's worth trying to fix this for 5.5 and earlier, or just
> > switch to the device-managed interface for 5.6 and forget about 5.5 and
> > earlier?
> 
> I suspect it's going to be quite some trickery to fix this properly
> and everywhere, even for just one driver. Lots of drm drivers
> unfortunately use anti-patterns with wrong lifetimes (e.g. you can't
> use devm_kmalloc for anything that hangs of a drm_device, like
> plane/crtc/connector). Except when it's for a real hotunpluggable
> device (usb) we've never bothered backporting these fixes. Too much
> broken stuff unfortunately.

While being at it:  How would a driver cleanup properly cleanup gem
objects created by userspace on hotunbind?  Specifically a gem object
pinned to vram?

cheers,
  Gerd