Created attachment 114829 system bus: do not allow stopping the system dbus-daemon
There is nothing that prevents D-Bus from stopping very early, way earlier than all of the Type=dbus services. There is an attempt to prevent that as systemd implies "After=dbus.socket" for Type=dbus units, but that doesn't save us: you can't re-start D-Bus after shutting it down and expect things to just work, as it loses all of its state. Putting dbus.service Before basic.target was considered and rejected, because it's a recipe for cyclic dependencies: as soon as dbus.service wants to be After anything that is After basic.target (e.g. NIS and other user databases, or remote filesystems) you get a cycle. dbus-daemon does not need to start early, it only needs to stop late. systemd has a final killing spree before it unmounts the file systems, which should be sufficient to avoid dbus-daemon preventing a separate /usr from being unmounted; this does not consider KillMode. dbus-daemon doesn't need to do anything special during shutdown, so it's OK that it survives until then. Based on a suggestion from Michael Biebl and Martin Pitt. --- How's this? I made the stop command be "echo" instead of "true" so that it leaves a hint in systemctl status if someone tries to stop it by hand. Unfortunately, "systemctl restart dbus" (which was never supported either) will now start a second dbus-daemon in parallel with the first, and in my testing, the second one will get all new connections. Any ideas for how to avoid that? Perhaps it would be better to make the stop command exit nonzero? ... but then we'd log scary messages during a normal shutdown, which is no better really. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1438612 Title: remote file systems hang on shutdown, D-BUS stops too early To manage notifications about this bug go to: https://bugs.launchpad.net/dbus/+bug/1438612/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
