PERFORCE change 167260 for review

[Marko Zec]

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