From owner-p4-projects@FreeBSD.ORG Wed Aug 12 22:44:51 2009 Return-Path: Delivered-To: p4-projects@freebsd.org Received: by hub.freebsd.org (Postfix, from userid 32767) id 799181065677; Wed, 12 Aug 2009 22:44:51 +0000 (UTC) Delivered-To: perforce@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1FF361065673 for ; Wed, 12 Aug 2009 22:44:51 +0000 (UTC) (envelope-from julian@elischer.org) Received: from outQ.internet-mail-service.net (outq.internet-mail-service.net [216.240.47.240]) by mx1.freebsd.org (Postfix) with ESMTP id 05FCC8FC3F for ; Wed, 12 Aug 2009 22:44:50 +0000 (UTC) Received: from idiom.com (mx0.idiom.com [216.240.32.160]) by out.internet-mail-service.net (Postfix) with ESMTP id C0C2DB15FD; Wed, 12 Aug 2009 15:44:50 -0700 (PDT) X-Client-Authorized: MaGic Cook1e X-Client-Authorized: MaGic Cook1e X-Client-Authorized: MaGic Cook1e Received: from julian-mac.elischer.org (home.elischer.org [216.240.48.38]) by idiom.com (Postfix) with ESMTP id 126372D6018; Wed, 12 Aug 2009 15:44:49 -0700 (PDT) Message-ID: <4A8345E1.1070301@elischer.org> Date: Wed, 12 Aug 2009 15:44:49 -0700 From: Julian Elischer User-Agent: Thunderbird 2.0.0.22 (Macintosh/20090605) MIME-Version: 1.0 To: Marko Zec References: <200908122108.n7CL8uhJ058398@repoman.freebsd.org> <4A833B16.2040301@elischer.org> <200908130034.57133.zec@freebsd.org> In-Reply-To: <200908130034.57133.zec@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Perforce Change Reviews , Robert Watson Subject: Re: PERFORCE change 167260 for review X-BeenThere: p4-projects@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: p4 projects tree changes List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 12 Aug 2009 22:44:52 -0000 Marko Zec wrote: > On Wednesday 12 August 2009 23:58:46 Julian Elischer wrote: >> Marko Zec wrote: > ... >>> @@ -710,22 +715,36 @@ >>> .pr_input = div_input, >>> .pr_ctlinput = div_ctlinput, >>> .pr_ctloutput = ip_ctloutput, >>> - .pr_init = NULL, >>> + .pr_init = div_init, >>> .pr_usrreqs = &div_usrreqs >> If you are going to make pr_init() called for every vnet then >> pr_destroy should be as well. But in fact that is not really safe. >> (either of them) >> >> The trouble is that we can not guarantee that other protocols can >> handle being called multiple times in their init and destroy methods. >> Especially 3rd party protocols. >> >> We need to ensure only protocols that have been converted to run >> with multiple vnets are ever called with multiple vnets. >> >> for this reason the only safe way to do this is via the VNET_SYSINIT >> and VNET_SYSUNINIT calls. > > That would mean you would have to convert most if not all of the existing > things that hang off of protosw-s in netinet, netinet6 etc. to use > VNET_SYSINT / VNET_SYSUNIT instead of protosw->pr_init(). So the short > answer is no. robert has done just that. > > I cannot recall that we ever discussed or planned to be able to mix > virtualized with non-virtualized protocols in the same kernel. That would be > a horrible mess, and I cannot even imagine having say a multi-instance INET > with a single-instance INET6 kernel, shared among all the vnets. To start > with, how would you decide that you're not allowed to process an IPv6 packet > received on the wire in a non-default vnet in such an environment? Do we > have the infrastructure in place necessary for preventing doing say a > ifconfig lo0 ::1 in a non-default vnet in such an hypotetical setup? The > answer is no. > I agree that it is horrible and we have not said that it will all work > VNET_SYSINIT is nice, but proper special-casing changes required to support > single-instance protocols to work only with vnet0 and not with the other > protocols are simply not there, and I hope will never be, because I fear they > would be highly intrusive, difficult to verify and maintain, and probably > also have an impact on performance. > > A proper solution for the issue you are raising could be something that would > prevent modules assuming our stack is compiled as single-instance to be > kldloaded if the kernel was actually built with multi-instance stack support. > I think Robert (cc-ed) had some ideas on how to accomplish this by having > such modules depend on a magic global variable (say __no_vnet_support) to be > available. > > All the current "base" protocols are already using pr_init() in multi-instance > mode in options VIMAGE case. So I see no reason for ip_divert not being > allowed to leverage on the same mechanism. > > Re. pr_destroy(), you're right, patch already submitted to p4... > > Marko