Re: [PATCH] drm/i915: fix up error cleanup in i915_gem_object_bind_to_gtt

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Jul 22, 2013 at 01:12:30PM -0700, Ben Widawsky wrote:
> On Mon, Jul 22, 2013 at 12:12:38PM +0200, Daniel Vetter wrote:
> > This has been broken in
> > 
> > commit 2f63315692b1d3c055972ad33fc7168ae908b97b
> > Author: Ben Widawsky <ben@bwidawsk.net>
> > Date:   Wed Jul 17 12:19:03 2013 -0700
> > 
> >     drm/i915: Create VMAs
> > 
> > which resulted in an OOPS the first time around we've hit -ENOSPC.
> > 
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67156
> > Cc: Imre Deak <imre.deak@intel.com>
> > Cc: Ben Widawsky <ben@bwidawsk.net>
> > Tested-by: meng <mengmeng.meng@intel.com>
> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > ---
> >  drivers/gpu/drm/i915/i915_gem.c | 14 ++++++++------
> >  1 file changed, 8 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> > index cfa6588..c87a6ec 100644
> > --- a/drivers/gpu/drm/i915/i915_gem.c
> > +++ b/drivers/gpu/drm/i915/i915_gem.c
> > @@ -3121,8 +3121,8 @@ i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
> >  
> >  	vma = i915_gem_vma_create(obj, &dev_priv->gtt.base);
> >  	if (IS_ERR(vma)) {
> > -		i915_gem_object_unpin_pages(obj);
> > -		return PTR_ERR(vma);
> > +		ret = PTR_ERR(vma);
> > +		goto err_unpin;
> >  	}
> 
> Adding the extra goto here seems pointless to me.

Like explained on irc, that's just to have a nice OCD reverse err_foo:
label stacking at the end of the function.

> 
> >  
> >  search_free:
> > @@ -3138,17 +3138,17 @@ search_free:
> >  		if (ret == 0)
> >  			goto search_free;
> >  
> > -		goto err_out;
> > +		goto err_free_vma;
> >  	}
> 
> My preference would be to exit early in drm_mm_remove_node() if the node
> isn't allocated. I think at least we should add a WARN to
> drm_mm_remove_node if the node->allocated == 0.

Hm, good idea. I'll create a quick patch.

> >  	if (WARN_ON(!i915_gem_valid_gtt_space(dev, &vma->node,
> >  					      obj->cache_level))) {
> >  		ret = -EINVAL;
> > -		goto err_out;
> > +		goto err_remove_node;
> >  	}
> >  
> >  	ret = i915_gem_gtt_prepare_object(obj);
> >  	if (ret)
> > -		goto err_out;
> > +		goto err_remove_node;
> >  
> >  	list_move_tail(&obj->global_list, &dev_priv->mm.bound_list);
> >  	list_add_tail(&obj->mm_list, &vm->inactive_list);
> > @@ -3167,9 +3167,11 @@ search_free:
> >  	i915_gem_verify_gtt(dev);
> >  	return 0;
> >  
> > -err_out:
> > +err_remove_node:
> >  	drm_mm_remove_node(&vma->node);
> > +err_free_vma:
> >  	i915_gem_vma_destroy(vma);
> > +err_unpin:
> >  	i915_gem_object_unpin_pages(obj);
> >  	return ret;
> >  }
> 
> Reviewed-by: Ben Widawsky <ben@bwidawsk.net>

Queued for -next, thanks for the review.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch