drm/nouveau: replace some open-coded mm_initialised checks

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/core/mm.c

@@ -234,15 +234,18 @@ nouveau_mm_init(struct nouveau_mm *mm, u32 offset, u32 length, u32 block)
 int
 nouveau_mm_fini(struct nouveau_mm *mm)
 {
-	struct nouveau_mm_node *node, *heap =
-		list_first_entry(&mm->nodes, struct nouveau_mm_node, nl_entry);
-	int nodes = 0;
+	if (nouveau_mm_initialised(mm)) {
+		struct nouveau_mm_node *node, *heap =
+			list_first_entry(&mm->nodes, typeof(*heap), nl_entry);
+		int nodes = 0;
+
+		list_for_each_entry(node, &mm->nodes, nl_entry) {
+			if (WARN_ON(nodes++ == mm->heap_nodes))
+				return -EBUSY;
+		}
 
-	list_for_each_entry(node, &mm->nodes, nl_entry) {
-		if (WARN_ON(nodes++ == mm->heap_nodes))
-			return -EBUSY;
+		kfree(heap);
 	}
 
-	kfree(heap);
 	return 0;
 }

drivers/gpu/drm/nouveau/core/include/core/mm.h

@@ -21,6 +21,12 @@ struct nouveau_mm {
 	int heap_nodes;
 };
 
+static inline bool
+nouveau_mm_initialised(struct nouveau_mm *mm)
+{
+	return mm->block_size != 0;
+}
+
 int  nouveau_mm_init(struct nouveau_mm *, u32 offset, u32 length, u32 block);
 int  nouveau_mm_fini(struct nouveau_mm *);
 int  nouveau_mm_head(struct nouveau_mm *, u8 type, u32 size_max, u32 size_min,

drivers/gpu/drm/nouveau/core/subdev/fb/base.c

@@ -85,12 +85,8 @@ nouveau_fb_destroy(struct nouveau_fb *pfb)
 
 	for (i = 0; i < pfb->tile.regions; i++)
 		pfb->tile.fini(pfb, i, &pfb->tile.region[i]);
-
-	if (pfb->tags.block_size)
-		nouveau_mm_fini(&pfb->tags);
-
-	if (pfb->vram.block_size)
-		nouveau_mm_fini(&pfb->vram);
+	nouveau_mm_fini(&pfb->tags);
+	nouveau_mm_fini(&pfb->vram);
 
 	nouveau_subdev_destroy(&pfb->base);
 }