[Intel-gfx] [PATCH v4 07/12] drm/i915: GEM operations need to be done under the big lock

[Daniel Vetter]

On Thu, Feb 11, 2016 at 10:13:30AM +0000, Chris Wilson wrote:
> On Tue, Feb 02, 2016 at 02:46:19PM +0000, Tvrtko Ursulin wrote:
> > From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > 
> > VMA creation and GEM list management need the big lock.
> > 
> > v2:
> > 
> > Mutex unlock ended on the wrong path somehow. (0-day, Julia Lawall)
> > 
> > Not to mention drm_gem_object_unreference was there in existing
> > code with no mutex held.
> > 
> > v3:
> > 
> > Some callers of i915_gem_object_create_stolen_for_preallocated
> > already hold the lock so move the mutex into the other caller
> > as well.
> > 
> > v4:
> > 
> > Changed to lockdep_assert_held. (Chris Wilson)
> > 
> > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> 
> Also
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> :)
> 
> Daniel, what did you think of having a config option to turn
> lockdep_assert_held into WARN_ON(!mutex_is_locked()) when lockdep is not
> fully-enabled?

I like, and kinda would even go as far as making it the default. But that
might upset some performance concious folks, so Kconfig seems fine. Cany
you please submit that to a wider audience? Then we'd never have to have
this discussion again ;-)

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch