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

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Message-ID: <e1667898-9189-bb32-0510-4c9d22aaf8cb@6wind.com>
Date:   Wed, 21 Nov 2018 21:58:42 +0100
From:   Nicolas Dichtel <nicolas.dichtel@...nd.com>
To:     David Ahern <dsahern@...il.com>, davem@...emloft.net
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next 2/4] netns: add support of NETNSA_TARGET_NSID

Le 21/11/2018 à 19:05, David Ahern a écrit :
> 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.
The target-nsid is not stored in net_cb (not needed). ref_net is set only if
tgt_net comes from TARGET_NSID. I can add a comment.