Re: [PATCH net-next 2/4] netns: add support of NETNSA_TARGET_NSID

[David Ahern <dsahern@gmail.com>]

On 11/21/18 4:01 AM, Nicolas Dichtel wrote:
>  static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
>  {
> -	struct net *net = sock_net(skb->sk);
>  	struct rtnl_net_dump_cb net_cb = {
> -		.net = net,
> +		.tgt_net = sock_net(skb->sk),
>  		.skb = skb,
>  		.cb = cb,
>  		.idx = 0,
>  		.s_idx = cb->args[0],
>  	};
> +	int err = 0;
>  
> -	if (cb->strict_check &&
> -	    nlmsg_attrlen(cb->nlh, sizeof(struct rtgenmsg))) {
> -			NL_SET_ERR_MSG(cb->extack, "Unknown data in network namespace id dump request");
> -			return -EINVAL;
> +	if (cb->strict_check) {
> +		err = rtnl_valid_dump_net_req(cb->nlh, skb->sk, &net_cb, cb);
> +		if (err < 0)
> +			goto end;
>  	}
>  
> -	spin_lock_bh(&net->nsid_lock);
> -	idr_for_each(&net->netns_ids, rtnl_net_dumpid_one, &net_cb);
> -	spin_unlock_bh(&net->nsid_lock);
> +	spin_lock_bh(&net_cb.tgt_net->nsid_lock);
> +	idr_for_each(&net_cb.tgt_net->netns_ids, rtnl_net_dumpid_one, &net_cb);
> +	spin_unlock_bh(&net_cb.tgt_net->nsid_lock);
>  
>  	cb->args[0] = net_cb.idx;
> -	return skb->len;
> +end:
> +	if (net_cb.ref_net)
> +		put_net(net_cb.tgt_net);

That is going to lead to confusion -- you check that ref_net is set put
do a put on tgt_net.  Other places using a target namespace use the nsid
as the key to whether a put_net is needed.


> +	return err < 0 ? err : skb->len;
>  }
>  
>  static void rtnl_net_notifyid(struct net *net, int cmd, int id)
>