Date: Thu, 13 Aug 2009 00:52:11 +0200 From: Marko Zec <zec@freebsd.org> To: Julian Elischer <julian@elischer.org> Cc: Perforce Change Reviews <perforce@freebsd.org>, Robert Watson <rwatson@freebsd.org> Subject: Re: PERFORCE change 167260 for review Message-ID: <200908130052.11423.zec@freebsd.org> In-Reply-To: <4A8345E1.1070301@elischer.org> References: <200908122108.n7CL8uhJ058398@repoman.freebsd.org> <200908130034.57133.zec@freebsd.org> <4A8345E1.1070301@elischer.org>
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On Thursday 13 August 2009 00:44:49 Julian Elischer wrote: > 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. hmm: tpx32% pwd /u/marko/svn/head/sys tpx32% fgrep -R .pr_init netinet netinet6 netipsec|fgrep -v .svn netinet/ip_divert.c: .pr_init = div_init, netinet/in_proto.c: .pr_init = ip_init, netinet/in_proto.c: .pr_init = udp_init, netinet/in_proto.c: .pr_init = tcp_init, netinet/in_proto.c: .pr_init = sctp_init, netinet/in_proto.c: .pr_init = icmp_init, netinet/in_proto.c: .pr_init = encap_init, netinet/in_proto.c: .pr_init = encap_init, netinet/in_proto.c: .pr_init = encap_init, netinet/in_proto.c: .pr_init = encap_init, netinet/in_proto.c: .pr_init = encap_init, netinet/in_proto.c: .pr_init = rip_init, netinet6/in6_proto.c: .pr_init = ip6_init, netinet6/in6_proto.c: .pr_init = tcp_init, netinet6/in6_proto.c: .pr_init = icmp6_init, netinet6/in6_proto.c: .pr_init = encap_init, netinet6/in6_proto.c: .pr_init = encap_init, netinet6/ip6_mroute.c: .pr_init = pim6_init, netipsec/keysock.c: .pr_init = raw_init, > > 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 Then we shouldn't attempt to do it. Marko > > 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
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