Re: [patch net-next 1/3] net: devlink: allow to change namespaces

[David Miller]

From: Jiri Pirko <j...@resnulli.us>
Date: Sat, 27 Jul 2019 11:44:57 +0200

> +     if ((netns_pid_attr && (netns_fd_attr || netns_id_attr)) ||
> +         (netns_fd_attr && (netns_pid_attr || netns_id_attr)) ||
> +         (netns_id_attr && (netns_pid_attr || netns_fd_attr))) {
> +             NL_SET_ERR_MSG(info->extack, "multiple netns identifying 
> attributes specified");
> +             return ERR_PTR(-EINVAL);
> +     }

How about:

        if (!!a + !!b + !!c > 1) {
        ...

> +
> +     if (netns_pid_attr) {
> +             net = get_net_ns_by_pid(nla_get_u32(netns_pid_attr));
> +     } else if (netns_fd_attr) {
> +             net = get_net_ns_by_fd(nla_get_u32(netns_fd_attr));
> +     } else if (netns_id_attr) {
> +             net = get_net_ns_by_id(sock_net(skb->sk),
> +                                    nla_get_u32(netns_id_attr));
> +             if (!net)
> +                     net = ERR_PTR(-EINVAL);
> +     }
> +     if (IS_ERR(net)) {

I think this is going to be one of those cases where a compiler won't be able
to prove that 'net' is guaranteed to be initialized at this spot.  Please
rearrange this code somehow so that is unlikely to happen.

Thanks.