Re: domain_add(xxx) after domainfinalize...

On Sat, Aug 2, 2014 at 10:01 PM, John-Mark Gurney <jmg_at_funkthat.com> wrote:

> Svatopluk Kraus wrote this message on Sat, Aug 02, 2014 at 21:27 +0200:
> > On Sat, Aug 2, 2014 at 8:32 PM, John-Mark Gurney <jmg_at_funkthat.com>
> wrote:
> >
> > > Svatopluk Kraus wrote this message on Sat, Aug 02, 2014 at 15:20 +0200:
> > > > Well, I did not look at network stack for long time, so the following
> > > > things could be obsolete now, but at least:
> > > >
> > > > (1) There is some room left in mbuf header on its allocation, so
> > > protocols
> > > > (link) headers can be added in the front of data without need of
> > > > reallocation or data copying. The size of the room is evaluated from
> all
> > > > domains at boot time.
> > > >
> > > > (2) All network address masks are shared among domains and protocols
> in
> > > > mask radix tree. The tree is created with particular key size, which
> is
> > > > again evaluated from all domains as maximal size of all known
> addresses.
> > > >
> > > > So, if new domain added after these evaluations does not break both
> them
> > > > and some other things, there is no problem. Otherwise, some warnings
> are
> > > > always nice if things go bad.
> > >
> > > But would anyone who sees these issues know that this is the problem?
> > > And what would they do, report the problem?  We'd say, yeh, we know,
> > > but do you hit this every day?  Nope, ok, we won't fix it...
> > >
> > > > Maybe some function which examine new domain and say there is no
> risk to
> > > > add it would be nice.
> > >
> > > I agree...  These things should have been done in the first place, but
> > > clearly this warning wasn't enough to cause anyone to fix it.. :)
> >
> > You are right, but the warning is remainder that there is something
> > unresolved. Remove the warning and forget, imho, it's not well.
>
> Sorry, nine years[1] of the warning existing yet no fix clearly
> demonstrates that it's already been forgoten, otherwise it would have
> been fixed by now..
>
> Also, a bug report or XXX comment is enough IMO, and will probably
> receive the same amount of attention over the next nine years...
>
> [1] https://svnweb.freebsd.org/changeset/base/138239
>
>


I agree that the warning is pointless stres for anyone but network domain
developer. And such developer knows if he/she is careful enough to ignore
it. However, I still remember time when I was starting with FreeBSD kernel
development. So much things one should be aware of. In those time, any
however small glue, which could help, was appreciated. So, put the warning
under INVARIANTS or something like that as FreeBSD is open source and
without rookies will die. And no one wants to make kernel development
harder than it is.

Svata



>  --
>   John-Mark Gurney                              Voice: +1 415 225 5579
>
>      "All that I will do, has been done, All that I have, has not."
>