[Intel-gfx] [PATCH] drm/i915/fbdev: Check for existence of ifbdev->vma before operations

[Chris Wilson]

Quoting Tvrtko Ursulin (2017-07-04 10:59:29)
> 
> On 22/06/2017 17:02, Chris Wilson wrote:
> > Commit fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer
> > flushes") adds a dependency to ifbdev->vma when flushing the framebufer,
> > but the checks are only against the existence of the ifbdev->fb and not
> > against ifbdev->vma. This leaves a window of opportunity where we may
> > try to operate on the fbdev prior to it being probed (thanks to
> > asynchronous booting).
> 
> How about changing the intelfb_alloc to not write the fb to ifbdev but 
> instead return it to the caller, so intelfb_create could then set the 
> ifbdev->fb and ifbdev->vma atomically under the mutex?

Midlayer mishap.
-Chris