Re: rfc: udev should be able to re-exec itself

On Sat, Jun 2, 2012 at 1:45 AM, William Hubbs <w.d.hubbs <at> gmail.com> wrote:
> currently udev does not have a way to restart itself. This would be a
> useful feature, because we could then use this command when we upgrade
> or downgrade udev on user's systems so that the most current version of
> udev is always running.
>
> One of gentoo's developers did suggest a patch quite a while back, but
> some how it got lost in the shuffel. This patch will not apply now, but
> it gives the impression that something like this could be added very
> easily [1].
>
> Thoughts anyone?

We do not want daemons to re-execute themselves. It's far more
complicated than usually expected, and in most cases it should be
avoided.

The problem of interruption-free upgrades is in most cases solved with
systemd's socket activation. But I don't think any distribution uses
that possibility when they upgrade udev today, but they easily could,
all the things are there to make it work.

Udev should not re-execute itself, but stopped, installed, and
restarted. If you want fancy upgrade setups, use an init system that
supports that properly while keeping things simple, and which allows
interruption-free restarts by keeping the sockets open.

Don't hack up daemons with half-baken things; it's *really* hard to get right.

Thanks,