systemd acceptance, packaging guidelines (was Re: systemd and changes)

[Miloslav Trmač]

Lennart Poettering píše v St 25. 08. 2010 v 02:52 +0200: 
> On Tue, 24.08.10 20:14, Matt McCutchen (matt at mattmccutchen.net) wrote:
> > On Tue, 2010-08-24 at 23:31 +0200, Lennart Poettering wrote:
> > > On Tue, 24.08.10 16:38, Bill Nottingham (notting at redhat.com) wrote:
> > > > Lennart Poettering (mzerqung at 0pointer.de) said: 
> > > > > > - init shall support a mechanism to re-exec itself to not cause dirty
> > > > > >   inodes on shutdown; initscripts will use this method on shutdown.
> > > > > 
> > > > > This is bad. While we support this just fine I think it is a really bad
> > > > > idea to reexec init at shutdown. What's the point of this, can you elaborate on
> > > > > this? This smells to me as a workaround for brokeness in older init
> > > > > systems, and I don't see a reason why reexecing itself would be
> > > > > necessary for systemd.
> > > > 
> > > > If the libraries or binaries used by systemd are replaced during runtime,
> > > > and it is not re-executed on shutdown, the filesystem will have busy inodes
> > > > on shutdown. (If you'd like to take the filesystem semantics up with the
> > > > kernel, feel free to tilt at that windmill.)
<snip> 
> Well, what me still puzzles is this: the reexec is done asynchronously,
> via signals. Shouldn't this be done synchronously at least to make
> sure the daemon really is reexec'ed when we try to remount r/o?
The traditional solution is to reexec not on shutdown, but immediately
after init upgrade (which also frees the inodes early); this can still
race with shutdown in theory, but is probably good enough in practice.
Mirek