From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH nf-next] netns: add and use net_ns_barrier Date: Wed, 14 Jun 2017 09:20:25 -0500 Message-ID: <87wp8eabx2.fsf@xmission.com> References: <20170530093812.10712-1-fw@strlen.de> <87y3tcj3n7.fsf@xmission.com> <20170601085259.GA6067@breakpoint.cc> <20170613061656.GF18283@breakpoint.cc> <20170614084147.GC31030@salvia> Mime-Version: 1.0 Content-Type: text/plain Cc: Cong Wang , Florian Westphal , netfilter-devel@vger.kernel.org, Linux Kernel Network Developers To: Pablo Neira Ayuso Return-path: In-Reply-To: <20170614084147.GC31030@salvia> (Pablo Neira Ayuso's message of "Wed, 14 Jun 2017 10:41:47 +0200") Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Pablo Neira Ayuso 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 wrote: >> > Cong Wang wrote: >> >> On Thu, Jun 1, 2017 at 1:52 AM, Florian Westphal 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" 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