[Intel-gfx] [PATCH] drm/i915: hold ref on flip object until it completes

[Jesse Barnes]

On Wed, 10 Feb 2010 17:39:44 -0800
Eric Anholt <eric at anholt.net> wrote:

> On Wed, 10 Feb 2010 15:09:44 -0800, Jesse Barnes
> <jbarnes at virtuousgeek.org> wrote:
> > On Wed, 10 Feb 2010 15:07:26 -0800
> > Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> > 
> > > On Wed, 10 Feb 2010 23:07:06 +0000
> > > Owain Ainsworth <zerooa at googlemail.com> wrote:
> > > 
> > > > On Wed, Feb 10, 2010 at 02:55:56PM -0800, Jesse Barnes wrote:
> > > > > This will prevent things from falling over if the user frees
> > > > > the flip buffer before we complete the flip, since we'll hold
> > > > > an internal reference.
> > > > > 
> > > > > Reported-by: Kristian H??gsberg <krh at bitplanet.net>
> > > > > Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> > > > > 
> > > > > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > > > > b/drivers/gpu/drm/i915/intel_display.c index 2476fb4..372a2f5
> > > > > 100644 --- a/drivers/gpu/drm/i915/intel_display.c
> > > > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > > > @@ -4039,6 +4039,9 @@ void intel_finish_page_flip(struct
> > > > > drm_device *dev, int pipe)
> > > > > atomic_dec_and_test(&obj_priv->pending_flip))
> > > > > DRM_WAKEUP(&dev_priv->pending_flip_queue);
> > > > > schedule_work(&work->work); +
> > > > > +	/* Drop the flip ref we took when the ioctl was
> > > > > called */
> > > > > +	drm_gem_object_unreference(work->pending_flip_obj);
> > > > >  }
> > > > 
> > > > two problems:
> > > > 1) not holdin struct mutex ((this is in interrupt context).
> > > > 2) you're doing that from interrupt context. stuff like the
> > > > unref, the possible free and unbind should not happen here.
> > > 
> > > Arg you're right.  I need to move this to the work handler.
> > 
> > So ignore the last one.  This one is less buggy.
> 
> OK, so apparently obvious isn't good enough.  You can all see how much
> I'm actually reviewing patches.
> 
> Rebased this one in instead.

Thanks, sorry for the first one, I should have caught that too.

-- 
Jesse Barnes, Intel Open Source Technology Center