drm: pre allocate node for create_block

For an upcoming patch where we introduce the i915 VMA, it's ideal to
have the drm_mm_node as part of the VMA struct (ie. it's pre-allocated).
Part of the conversion to VMAs is to kill off obj->gtt_space. Doing this
will break a bunch of code, but amongst them are 2 callers of
drm_mm_create_block(), both related to stolen memory.

It also allows us to embed the drm_mm_node into the object currently
which provides a nice transition over to the new code.

v2: Reordered to do before ripping out obj->gtt_offset.
Some minor cleanups made available because of reordering.

v3: s/continue/break on failed stolen node allocation (David)
Set obj->gtt_space on failed node allocation (David)
Only unref stolen (fix double free) on failed create_stolen (David)
Free node, and NULL it in failed create_stolen (David)
Add back accidentally removed newline (David)

CC: <dri-devel@lists.freedesktop.org>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Acked-by: David Airlie <airlied@linux.ie>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_mm.c

@@ -147,12 +147,10 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node,
 	}
 }
 
-struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
-					unsigned long start,
-					unsigned long size,
-					bool atomic)
+int drm_mm_create_block(struct drm_mm *mm, struct drm_mm_node *node,
+			unsigned long start, unsigned long size)
 {
-	struct drm_mm_node *hole, *node;
+	struct drm_mm_node *hole;
 	unsigned long end = start + size;
 	unsigned long hole_start;
 	unsigned long hole_end;
@@ -161,10 +159,6 @@ struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
 		if (hole_start > start || hole_end < end)
 			continue;
 
-		node = drm_mm_kmalloc(mm, atomic);
-		if (unlikely(node == NULL))
-			return NULL;
-
 		node->start = start;
 		node->size = size;
 		node->mm = mm;
@@ -184,11 +178,11 @@ struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
 			node->hole_follows = 1;
 		}
 
-		return node;
+		return 0;
 	}
 
 	WARN(1, "no hole found for block 0x%lx + 0x%lx\n", start, size);
-	return NULL;
+	return -ENOSPC;
 }
 EXPORT_SYMBOL(drm_mm_create_block);
 

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -629,14 +629,26 @@ void i915_gem_setup_global_gtt(struct drm_device *dev,
 
 	/* Mark any preallocated objects as occupied */
 	list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
+		int ret;
 		DRM_DEBUG_KMS("reserving preallocated space: %x + %zx\n",
 			      obj->gtt_offset, obj->base.size);
 
 		BUG_ON(obj->gtt_space != I915_GTT_RESERVED);
-		obj->gtt_space = drm_mm_create_block(&dev_priv->mm.gtt_space,
+		obj->gtt_space = kzalloc(sizeof(*obj->gtt_space), GFP_KERNEL);
+		if (!obj->gtt_space) {
+			DRM_ERROR("Failed to preserve object at offset %x\n",
+				  obj->gtt_offset);
+			continue;
+		}
+		ret = drm_mm_create_block(&dev_priv->mm.gtt_space,
+					  obj->gtt_space,
 					  obj->gtt_offset,
-						     obj->base.size,
-						     false);
+					  obj->base.size);
+		if (ret) {
+			DRM_DEBUG_KMS("Reservation failed\n");
+			kfree(obj->gtt_space);
+			obj->gtt_space = NULL;
+		}
 		obj->has_global_gtt_mapping = 1;
 	}
 

drivers/gpu/drm/i915/i915_gem_stolen.c

@@ -330,6 +330,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_object *obj;
 	struct drm_mm_node *stolen;
+	int ret;
 
 	if (dev_priv->mm.stolen_base == 0)
 		return NULL;
@@ -344,11 +345,15 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	if (WARN_ON(size == 0))
 		return NULL;
 
-	stolen = drm_mm_create_block(&dev_priv->mm.stolen,
-				     stolen_offset, size,
-				     false);
-	if (stolen == NULL) {
+	stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
+	if (!stolen)
+		return NULL;
+
+	ret = drm_mm_create_block(&dev_priv->mm.stolen, stolen, stolen_offset,
+				  size);
+	if (ret) {
 		DRM_DEBUG_KMS("failed to allocate stolen space\n");
+		kfree(stolen);
 		return NULL;
 	}
 
@@ -369,13 +374,18 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	 * later.
 	 */
 	if (drm_mm_initialized(&dev_priv->mm.gtt_space)) {
-		obj->gtt_space = drm_mm_create_block(&dev_priv->mm.gtt_space,
-						     gtt_offset, size,
-						     false);
-		if (obj->gtt_space == NULL) {
+		obj->gtt_space = kzalloc(sizeof(*obj->gtt_space), GFP_KERNEL);
+		if (!obj->gtt_space) {
+			DRM_DEBUG_KMS("-ENOMEM stolen GTT space\n");
+			goto unref_out;
+		}
+
+		ret = drm_mm_create_block(&dev_priv->mm.gtt_space,
+					  obj->gtt_space,
+					  gtt_offset, size);
+		if (ret) {
 			DRM_DEBUG_KMS("failed to allocate stolen GTT space\n");
-			drm_gem_object_unreference(&obj->base);
-			return NULL;
+			goto free_out;
 		}
 	} else
 		obj->gtt_space = I915_GTT_RESERVED;
@@ -387,6 +397,13 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	list_add_tail(&obj->mm_list, &dev_priv->mm.inactive_list);
 
 	return obj;
+
+free_out:
+	kfree(obj->gtt_space);
+	obj->gtt_space = NULL;
+unref_out:
+	drm_gem_object_unreference(&obj->base);
+	return NULL;
 }
 
 void

include/drm/drm_mm.h

@@ -138,10 +138,10 @@ static inline unsigned long drm_mm_hole_node_end(struct drm_mm_node *hole_node)
 /*
  * Basic range manager support (drm_mm.c)
  */
-extern struct drm_mm_node *drm_mm_create_block(struct drm_mm *mm,
+extern int drm_mm_create_block(struct drm_mm *mm,
+			       struct drm_mm_node *node,
 			       unsigned long start,
-					       unsigned long size,
-					       bool atomic);
+			       unsigned long size);
 extern struct drm_mm_node *drm_mm_get_block_generic(struct drm_mm_node *node,
 						    unsigned long size,
 						    unsigned alignment,
@@ -155,6 +155,7 @@ extern struct drm_mm_node *drm_mm_get_block_range_generic(
 						unsigned long start,
 						unsigned long end,
 						int atomic);
+
 static inline struct drm_mm_node *drm_mm_get_block(struct drm_mm_node *parent,
 						   unsigned long size,
 						   unsigned alignment)