repost fix for a real prime issue

[Daniel Vetter]

On Wed, Apr 10, 2013 at 10:56:42AM +1000, Dave Airlie wrote:
> Please don't bikeshed this with requirements to fix problems that
> are there now anyways. This is the simplest patch to fix an obvious
> problem, it doesn't fix all the other problems.
> 
> I should have merged this months ago, but people keep wanting a
> superpatch to fix everything.

Imo same review on the semantics of the patch itself still applies:

http://lists.freedesktop.org/archives/dri-devel/2012-December/032374.html

Two main things:
- I think the dma_buf reference attached to gem handles should be dropped
  in drm_gem_object_handle_free instead of drm_gem_handle_delete.
- I still have no idea what the drm_prime_lookup_buf_handle check in
  handle_to_fd is for ...

Note that the locking review was in a 2nd mail:

http://lists.freedesktop.org/archives/dri-devel/2012-December/032376.html

Imo this is an issue with this very patch since this patch also adds the
dma_buf reference on exported objects while a handle is open.

So I don't think my original review asked for a superpatch to fix all the
issues with currently have, but only for a correct one implementing the
handle holds ref on exported obj logic ;-)

I'll try to pimp the self import testcase we have a bit to exercise these
corner cases.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch