drm/amdgpu: fix error handling in amdgpu_cs_user_fence_chunk

Slowly leaking memory one page at a time :)
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c

@@ -40,6 +40,7 @@ static int amdgpu_cs_user_fence_chunk(struct amdgpu_cs_parser *p,
 {
 	struct drm_gem_object *gobj;
 	unsigned long size;
+	int r;
 
 	gobj = drm_gem_object_lookup(p->filp, data->handle);
 	if (gobj == NULL)
@@ -51,20 +52,26 @@ static int amdgpu_cs_user_fence_chunk(struct amdgpu_cs_parser *p,
 	p->uf_entry.tv.shared = true;
 	p->uf_entry.user_pages = NULL;
 
-	size = amdgpu_bo_size(p->uf_entry.robj);
-	if (size != PAGE_SIZE || (data->offset + 8) > size)
-		return -EINVAL;
-
-	*offset = data->offset;
-
 	drm_gem_object_put_unlocked(gobj);
 
+	size = amdgpu_bo_size(p->uf_entry.robj);
+	if (size != PAGE_SIZE || (data->offset + 8) > size) {
+		r = -EINVAL;
+		goto error_unref;
+	}
+
 	if (amdgpu_ttm_tt_get_usermm(p->uf_entry.robj->tbo.ttm)) {
-		amdgpu_bo_unref(&p->uf_entry.robj);
-		return -EINVAL;
+		r = -EINVAL;
+		goto error_unref;
 	}
 
+	*offset = data->offset;
+
 	return 0;
+
+error_unref:
+	amdgpu_bo_unref(&p->uf_entry.robj);
+	return r;
 }
 
 static int amdgpu_cs_bo_handles_chunk(struct amdgpu_cs_parser *p,