netdev - Re: [patch 0/6] netfilter: ctnetlink allocation improvement

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Date:	Tue, 17 Mar 2009 11:24:51 +0100
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	Patrick McHardy <kaber@...sh.net>
CC:	Holger Eitzenberger <holger@...zenberger.org>,
	David Miller <davem@...emloft.net>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [patch 0/6] netfilter: ctnetlink allocation improvement

Hi Patrick,

Patrick McHardy wrote:
> These patches look almost perfect, there's just one minor thing
> that should be fixed from my perspective (from patch 4):
> 
>> +    l3proto = nf_ct_l3proto_find_get(tuple->src.l3num);
>> +    len += l3proto->nla_size;
>> +    nf_ct_l3proto_put(l3proto);
>> +
>> +    l4proto = nf_ct_l4proto_find_get(tuple->src.l3num,
>> tuple->dst.protonum);
>> +    len += l4proto->nla_size;
>> +    nf_ct_l4proto_put(l4proto);
>> +
>> +    return alloc_skb(len, gfp);
> 
> Its preferrable not to use module reference counting during packet
> processing, the protocols can be accessed safely using RCU. I thought
> I had fixed all those areas, but I now notice that ctnetlink is full
> of similar spots and takes and drops module references quite
> excessively. So just leave it as it is I guess, this should be fully
> fixed anyways.

Indeed, there are still a couple of module reference spots. We only
remove them from the event delivery path.

> I'll wait a few hours for others to comment before applying your
> patches.

Hm, it seems that our patches follows two different principles. AFAICS,
Holger calculates an approximate message size to avoid trimming, while I
calculate the exact message size.

-- 
"Los honestos son inadaptados sociales" -- Les Luthiers
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