netdev - Re: [PATCH 02/17] netfilter: nat: remove module reference counting from NAT protocols

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Date:	Mon, 21 Nov 2011 15:59:14 +0100
From:	Patrick McHardy <kaber@...sh.net>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
	ulrich.weber@...hos.com
Subject: Re: [PATCH 02/17] netfilter: nat: remove module reference counting
 from NAT protocols

On 11/21/2011 08:36 AM, Eric Dumazet wrote:
> Le lundi 21 novembre 2011 à 06:45 +0100, kaber@...sh.net a écrit :
>> From: Patrick McHardy<kaber@...sh.net>
>>
>> The only remaining user of NAT protocol module reference counting is NAT
>> ctnetlink support. Since this is a fairly short sequence of code, convert
>> over to use RCU and remove module reference counting.
>>
>> Signed-off-by: Patrick McHardy<kaber@...sh.net>
>> @@ -612,16 +592,18 @@ static int nfnetlink_parse_nat_proto(struct nlattr *attr,
>>   	if (err<  0)
>>   		return err;
>>
>> -	npt = nf_nat_proto_find_get(nf_ct_protonum(ct));
>> +	rcu_read_lock();
>> +	npt = __nf_nat_proto_find(nf_ct_protonum(ct));
>>   	if (npt->nlattr_to_range)
>>   		err = npt->nlattr_to_range(tb, range);
>> -	nf_nat_proto_put(npt);
>> +	rcu_read_unlock();
>>   	return err;
>>   }
> Seems good, but you should explain in changelog why its safe.
>
> (Using rcu also means special action must be taken in the write side,
> here the module removal)

I'll update the changelog for the next submission.

>>
>>   static const struct nla_policy nat_nla_policy[CTA_NAT_MAX+1] = {
>>   	[CTA_NAT_MINIP]		= { .type = NLA_U32 },
>>   	[CTA_NAT_MAXIP]		= { .type = NLA_U32 },
>> +	[CTA_NAT_PROTO]		= { .type = NLA_NESTED },
>>   };
> I just dont understand this part :-

Yeah, it doesn't belong into this patch.

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