netdev - Re: [PATCH for 2.6.33] conntrack: restrict runtime hashsize modifications

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Date:	Fri, 05 Feb 2010 11:19:08 +0100
From:	Patrick McHardy <kaber@...sh.net>
To:	Jon Masters <jonathan@...masters.org>
CC:	Alexey Dobriyan <adobriyan@...il.com>, davem@...emloft.net,
	eric.dumazet@...il.com, netdev@...r.kernel.org,
	netfilter-devel@...r.kernel.org
Subject: Re: [PATCH for 2.6.33] conntrack: restrict runtime hashsize modifications

Jon Masters wrote:
> On Fri, 2010-02-05 at 11:00 +0100, Patrick McHardy wrote:
>>>> How about this (so far untested) patch? The htable_size is moved into
>>>> the per-namespace struct and initialized from the current (global)
>>>> value of nf_conntrack_htable_size. Changes through sysfs are still
>>>> permitted, but only affect the init namespace and newly created ones.
>>> No matter what we do, it's a hack!
>>>
>>>> Additionally I removed reinitializing the hash random value when
>>>> changing the hash size since that also requires to rehash in all
>>>> namespaces.
>>> I'm not fond of this, because we're not even closely going to allow changing
>>> hashtable size per-netns. As such having actual per-netns hashtable size
>>> just slows down everything.
>> Actually it doesn't seem like much more work to allow changing
>> table size, the main problem is that sysfs module parameters
>> don't seem to fit into the network namespace model at all.
> 
> That was the reason I initially suggested we need a better way to expose
> netns topology through sysfs, which I still think is a good idea. How
> about this...it's dangerous as it is right now to leave things global. I
> suggest leaving the existing sysfs module parameter that only actually
> touches the init_net ct and get the rest fixed up, then adding support
> for exposing the topology better in sysfs and tweaking per-ns bits.
> 
> But maybe you want to fix it all at the same time.

No, right now I only want to fix the remaining bugs. I'll leave
everything else to the netns people.
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