Re: Bug#1115317: Technical Committee resolution on /var/lock and systemd

[Josh Triplett <josh@joshtriplett.org>]

Helmut Grohne wrote:
> Also keep in mind that we cannot just move packages from /var/lock based
> locking to flock() based locking one at a time. If two different
> packages compete about a device and they use different locking schemes,
> they'll both think they had exclusive access. Going for flock()
> practically needs to be a flag-day transition where all packages are
> updated at roughly the same time.

I think it would be possible to make this incremental in two steps:

- First, port everything using `/var/lock` or `/run/lock` to lock
  something that has an obvious `flock` target (e.g. a serial device),
  one-by-one, to use `flock` *and*` a lockfile, silently ignoring
  permission errors iff it successfully acquired the `flock`.

- Second, when everything has been ported *and* we've been through some
  transition period (using package dependencies in Debian and allowing
  some time for third-party sotware), we let software start deleting the
  lockfile code.