[Intel-gfx] [PATCH 2/4] drm/i915: Support for creating Stolen memory backed objects

[Ankitprasad Sharma]

On Tue, 2015-09-15 at 10:49 +0100, Chris Wilson wrote:
> On Tue, Sep 15, 2015 at 02:03:25PM +0530, ankitprasad.r.sharma at intel.com wrote:
> >  i915_gem_create(struct drm_file *file,
> >  		struct drm_device *dev,
> >  		uint64_t size,
> > +		uint32_t flags,
> >  		uint32_t *handle_p)
> >  {
> >  	struct drm_i915_gem_object *obj;
> > @@ -385,8 +386,31 @@ i915_gem_create(struct drm_file *file,
> >  	if (size == 0)
> >  		return -EINVAL;
> >  
> > +	if (flags & __I915_CREATE_UNKNOWN_FLAGS)
> > +		return -EINVAL;
> > +
> >  	/* Allocate the new object */
> > -	obj = i915_gem_alloc_object(dev, size);
> > +	if (flags & I915_CREATE_PLACEMENT_STOLEN) {
> > +		mutex_lock(&dev->struct_mutex);
> > +		obj = i915_gem_object_create_stolen(dev, size);
> > +		if (!obj) {
> > +			mutex_unlock(&dev->struct_mutex);
> > +			return -ENOMEM;
> 
> Note that you should change the i915_gem_object_create_stolen() to
> report the precise error, as with the eviction support we may trigger
> EINTR. Also ENOSPC will be preferrable for requesting a larger stolen
> object than the available space (to help distinguish between true oom).
> -Chris
I would prefer to do this as a separate patch, as this might require a
restructuring of the gem_stolen.c to some extent, something like this:

@@ -465,29 +467,29 @@ i915_gem_object_create_stolen(struct drm_device
*dev, u64 size)
 	int ret;
 
 	if (!drm_mm_initialized(&dev_priv->mm.stolen))
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	DRM_DEBUG_KMS("creating stolen object: size=%llx\n", size);
 	if (size == 0)
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
 	if (!stolen)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	ret = i915_gem_stolen_insert_node(dev_priv, stolen, size, 4096);
 	if (ret) {
 		kfree(stolen);
-		return NULL;
+		return ERR_PTR(-ENOSPC);
 	}
 
 	obj = _i915_gem_object_create_stolen(dev, stolen);
-	if (obj)
+	if (!IS_ERR(obj))
 		return obj;
 
 	i915_gem_stolen_remove_node(dev_priv, stolen);
 	kfree(stolen);
-	return NULL;
+	return obj;
 }
 

Thanks,
Ankit