IB: Fix return value in ib_device_register_sysfs()

If kobject_create_and_add() fails and returns NULL, the current code
in ib_device_register_sysfs() does not set ret and hence returns 0.
Set ret to -ENOMEM for this failure, so that the caller knows that
ib_device_register_sysfs() actually failed.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/sysfs.c

@@ -686,8 +686,10 @@ int ib_device_register_sysfs(struct ib_device *device)
 
 	device->ports_parent = kobject_create_and_add("ports",
 					kobject_get(&class_dev->kobj));
-	if (!device->ports_parent)
+	if (!device->ports_parent) {
+		ret = -ENOMEM;
 		goto err_put;
+	}
 
 	if (device->node_type == RDMA_NODE_IB_SWITCH) {
 		ret = add_port(device, 0);