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Date: Wed, 14 Jun 2017 09:20:25 -0500 From: ebiederm@...ssion.com (Eric W. Biederman) To: Pablo Neira Ayuso <pablo@...filter.org> Cc: Cong Wang <xiyou.wangcong@...il.com>, Florian Westphal <fw@...len.de>, netfilter-devel@...r.kernel.org, Linux Kernel Network Developers <netdev@...r.kernel.org> Subject: Re: [PATCH nf-next] netns: add and use net_ns_barrier Pablo Neira Ayuso <pablo@...filter.org> writes: > Hi! > > On Tue, Jun 13, 2017 at 09:35:20AM -0700, Cong Wang wrote: >> On Mon, Jun 12, 2017 at 11:16 PM, Florian Westphal <fw@...len.de> wrote: >> > Cong Wang <xiyou.wangcong@...il.com> wrote: >> >> On Thu, Jun 1, 2017 at 1:52 AM, Florian Westphal <fw@...len.de> wrote: >> >> > Joe described it nicely, problem is that after unload we may have >> >> > conntracks that still have a nf_conn_help extension attached that >> >> > has a pointer to a structure that resided in the (unloaded) module. >> >> >> >> Why not hold a refcnt for its module? >> > >> > That would work as well. >> > >> > I'm not sure its nice to disallow rmmod of helper modules if they are >> > used by a connection however. >> >> I am _not_ suggesting to disallow rmmod. >> >> > >> > Right now you can "rmmod nf_conntrack_foo" at any time and this should >> > work just fine without first having to flush affected conntracks >> > manually. >> >> My point is that since netns wq could invoke code of that module, >> why it doesn't hold a refcnt of that module? >> >> I am not familiar with netfilter code base so not sure if that is >> hard to do or not, but it looks more elegant than this barrier. > > Florian has added a new native interface to integrate helpers into > nftables in a much better way than we do now, that allows much more > fine grain configuration. This new interface bumps refcounts on > helpers as you suggest. > > However, we still have to sort of keep the existing behaviour around, > people has been relying on this rmmod feature to globally disable > helpers. It's very old thing indeed and as you can see, very sparse > grain for the netns era... But still I think we need this. > > So I'm inclined to take this, and keep an eye to deprecate this > behaviour in a several years ahead once. Probably we can get rid of > this barrier at some point. Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com> If it works I don't have any problems with the code and it sounds like it works. My apologies for the delay. There is an email black hole between Forian and myself and I missed his replies. Which gave me a very distored picture of the conversation. Eric
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