drm/nouveau/prime: Extend DMA reservation object lock

Prior to commit 019cbd4a ("drm/nouveau: Initialize GEM object before
TTM object"), the reservation object was locked across all of the buffer
object creation.

After splitting nouveau_bo_new() into separate nouveau_bo_alloc() and
nouveau_bo_init() functions, the reservation object is passed to the
latter, so the lock needs to be held across that function as well.

Fixes: 019cbd4a ("drm/nouveau: Initialize GEM object before TTM object")
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_prime.c

@@ -60,6 +60,7 @@ struct drm_gem_object *nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 							 struct sg_table *sg)
 {
 	struct nouveau_drm *drm = nouveau_drm(dev);
+	struct drm_gem_object *obj;
 	struct nouveau_bo *nvbo;
 	struct dma_resv *robj = attach->dmabuf->resv;
 	u64 size = attach->dmabuf->size;
@@ -71,9 +72,10 @@ struct drm_gem_object *nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 
 	dma_resv_lock(robj, NULL);
 	nvbo = nouveau_bo_alloc(&drm->client, &size, &align, flags, 0, 0);
-	dma_resv_unlock(robj);
-	if (IS_ERR(nvbo))
-		return ERR_CAST(nvbo);
+	if (IS_ERR(nvbo)) {
+		obj = ERR_CAST(nvbo);
+		goto unlock;
+	}
 
 	nvbo->valid_domains = NOUVEAU_GEM_DOMAIN_GART;
 
@@ -82,16 +84,22 @@ struct drm_gem_object *nouveau_gem_prime_import_sg_table(struct drm_device *dev,
 	ret = drm_gem_object_init(dev, &nvbo->bo.base, size);
 	if (ret) {
 		nouveau_bo_ref(NULL, &nvbo);
-		return ERR_PTR(-ENOMEM);
+		obj = ERR_PTR(-ENOMEM);
+		goto unlock;
 	}
 
 	ret = nouveau_bo_init(nvbo, size, align, flags, sg, robj);
 	if (ret) {
 		nouveau_bo_ref(NULL, &nvbo);
-		return ERR_PTR(ret);
+		obj = ERR_PTR(ret);
+		goto unlock;
 	}
 
-	return &nvbo->bo.base;
+	obj = &nvbo->bo.base;
+
+unlock:
+	dma_resv_unlock(robj);
+	return obj;
 }
 
 int nouveau_gem_prime_pin(struct drm_gem_object *obj)