drm/nouveau: allow nouveau_fence_ref() to be a noop

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

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -98,12 +98,7 @@ nv10_bo_put_tile_region(struct drm_device *dev, struct nouveau_drm_tile *tile,
 
 	if (tile) {
 		spin_lock(&drm->tile.lock);
-		if (fence) {
-			/* Mark it as pending. */
-			tile->fence = fence;
-			nouveau_fence_ref(fence);
-		}
-
+		tile->fence = nouveau_fence_ref(fence);
 		tile->used = false;
 		spin_unlock(&drm->tile.lock);
 	}
@@ -1462,14 +1457,12 @@ nouveau_ttm_tt_unpopulate(struct ttm_tt *ttm)
 void
 nouveau_bo_fence(struct nouveau_bo *nvbo, struct nouveau_fence *fence)
 {
+	struct nouveau_fence *new_fence = nouveau_fence_ref(fence);
 	struct nouveau_fence *old_fence = NULL;
 
-	if (likely(fence))
-		nouveau_fence_ref(fence);
-
 	spin_lock(&nvbo->bo.bdev->fence_lock);
 	old_fence = nvbo->bo.sync_obj;
-	nvbo->bo.sync_obj = fence;
+	nvbo->bo.sync_obj = new_fence;
 	spin_unlock(&nvbo->bo.bdev->fence_lock);
 
 	nouveau_fence_unref(&old_fence);

drivers/gpu/drm/nouveau/nouveau_fence.c

@@ -306,6 +306,7 @@ nouveau_fence_unref(struct nouveau_fence **pfence)
 struct nouveau_fence *
 nouveau_fence_ref(struct nouveau_fence *fence)
 {
+	if (fence)
 		kref_get(&fence->kref);
 	return fence;
 }

drivers/gpu/drm/nouveau/nouveau_gem.c

@@ -106,7 +106,6 @@ nouveau_gem_object_unmap(struct nouveau_bo *nvbo, struct nouveau_vma *vma)
 
 	if (mapped) {
 		spin_lock(&nvbo->bo.bdev->fence_lock);
-		if (nvbo->bo.sync_obj)
 		fence = nouveau_fence_ref(nvbo->bo.sync_obj);
 		spin_unlock(&nvbo->bo.bdev->fence_lock);
 	}
@@ -438,7 +437,6 @@ validate_sync(struct nouveau_channel *chan, struct nouveau_bo *nvbo)
 	int ret = 0;
 
 	spin_lock(&nvbo->bo.bdev->fence_lock);
-	if (nvbo->bo.sync_obj)
 	fence = nouveau_fence_ref(nvbo->bo.sync_obj);
 	spin_unlock(&nvbo->bo.bdev->fence_lock);