devlink: don't allow to change net namespace for FW_ACTIVATE reload action

The change on network namespace only makes sense during re-init reload
action. For FW activation it is not applicable. So check if user passed
an ATTR indicating network namespace change request and forbid it.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230213115836.3404039-1-jiri@resnulli.usSigned-off-by: Paolo Abeni <pabeni@redhat.com>

net/devlink/dev.c

@@ -476,6 +476,12 @@ int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
 		dest_net = devlink_netns_get(skb, info);
 		if (IS_ERR(dest_net))
 			return PTR_ERR(dest_net);
+		if (!net_eq(dest_net, devlink_net(devlink)) &&
+		    action != DEVLINK_RELOAD_ACTION_DRIVER_REINIT) {
+			NL_SET_ERR_MSG_MOD(info->extack,
+					   "Changing namespace is only supported for reinit action");
+			return -EOPNOTSUPP;
+		}
 	}
 
 	err = devlink_reload(devlink, dest_net, action, limit, &actions_performed, info->extack);