linux-kernel - Re: [PATCH] netfilter: per netns nf_conntrack

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Message-ID: <20100203195153.GA5576@x200>
Date:	Wed, 3 Feb 2010 21:51:53 +0200
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	Jon Masters <jonathan@...masters.org>
Cc:	Patrick McHardy <kaber@...sh.net>,
	Eric Dumazet <eric.dumazet@...il.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	netfilter-devel <netfilter-devel@...r.kernel.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH] netfilter: per netns nf_conntrack_cachep

On Wed, Feb 03, 2010 at 02:43:47PM -0500, Jon Masters wrote:
> On Wed, 2010-02-03 at 21:09 +0200, Alexey Dobriyan wrote:
> > On Wed, Feb 03, 2010 at 01:38:09PM -0500, Jon Masters wrote:
> > > *). Per namespace hashsize tracking. Existing code corrupts hashtables
> > > if the global size is changed when there is more than one netns
> > 
> > I think, no.
> > Changing hash size will change hashsize for all netns, current and future.
> 
> Nope. Look at the logic in nf_conntrack_set_hashsize where you iterate
> over init_net.ct.hash but don't touch other namespaces. So then you go
> setting nf_conntrack_htable_size and will deference that in accessing
> other per-namespace hashtables using the wrong size information.

> > > I also think it is necessary to expose net namespace layout
> > 
> > Not necessary. Why?
> 
> How am I as a sysadmin supposed to figure out which net namespaces exist
> on my system, and as a developer, supposed to debug these situations?

We don't expose many relations to userspace, and it's generally fine.

As a developer you fire a debugger and look at net_namespace_list.
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