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

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Date:	Fri, 05 Feb 2010 05:12:41 -0500
From:	Jon Masters <jonathan@...masters.org>
To:	Patrick McHardy <kaber@...sh.net>
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

On Fri, 2010-02-05 at 11:03 +0100, Patrick McHardy wrote:
> Jon Masters wrote:
> > On Thu, 2010-02-04 at 18:04 +0100, Patrick McHardy wrote:
> >>> How about alternatively moving nf_conntrack_hsize into the
> >>> per-namespace struct? It doesn't look more complicated or
> >>> intrusive and would allow to still change the init_net
> >>> hashsize. Also seems less hackish :)
> >> 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.
> > 
> > I moved the random seed into the per-ns context aswell. I think that's
> > better than having a global one, and you don't need to rehash all.
> 
> That's another possibility. But we don't loose anything by not
> reseeding during resize. It also shouldn't be possible to determine
> the seed from userspace in a namespace, so there's no real need
> to use seperate values.

Right, the risk there is hypothetical at best. But there's little lost
in putting it in per-ns and then you can rehash and truly make them
independent, which I think is really what netns is all about.

Jon.


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