PERFORCE change 167260 for review

[Julian Elischer]

Marko Zec wrote:
> 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,


AND for example:
in ./netinet/in_proto.c
VNET_DOMAIN_SET(inet);
includes
VNET_SYSINIT   ##### --> called for every vnet as created ####
    calls
vnet_domain_init()
    calls
domain_init()
    calls
protosw_init()
    which includes
              if (pr->pr_init)
                 (*pr->pr_init)();

so, robert is calling the init routine from each protocol
not the modevent.



> 
>>> 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
>