On Tue, 03.02.15 23:03, Michael Biebl (mbi...@gmail.com) wrote: > > While I just made this scenario up I think it's actually quite > > realistic, and I think it's a valid thing for admins to do.... > > Well, we could easily check if DefaultDependencies=yes in this case. > Actually, this is already what we do for the boot case. [1] > > So even with your made-up example, it would work. > > >> The thing is, you have to be extra careful to never, ever call a > >> restart/reload from such hook scripts. If those are triggered via > >> service or systemctl on a native or SysV script doesn't make a > >> difference. > > > > It is completely fine to enqueue restarts and reloads from hook > > scripts. However the emphasis is on *enqueue*. The issue is that you > > block on it, you shouldn't do that. > > > > On Fedora, iscsi is reloaded from an NM callout. If you ask me that's > > frickin' ugly, but it *is* supported as long as iscsi's reload is > > queued asynchronously instead of requested synchronously. In Fedora, > > the logic to make this async sits on the client side of things, it's > > not enforced by the engine in PID 1. > > > > The same really applies to Debian too... > > > >> It's simply to easy to cause a dead lock this way, and I think systemd > >> should try much harder to avoid such situations. > > > > Well, it would be great if we could solve the halting problem. But we > > can't. > > > > I mean, I am all ears regarding adding deadlock detection code. But I > > am really not convinced that breaking the engine for *everybody* just > > because *some* clients are weird is an option. > > Calling it "breaking the engine for everybody" is hyperbole. > > That said, do you have better ideas how we could avoid having systemd > easily being dead-locked on shutdown? > I'm all for solving it in a nicer way. But simply throwing the hands > in the air and saying, not our problem, doesn't help.
I made a clear recommendation: whenever commands are converted from sysv operations into systemctl operations, then add --no-block or --job-mode=ignore-deps to the systemctl command line, after checking that you are in startup or shutdown mode. Why wouldn't that suffice? Lennart -- Lennart Poettering, Red Hat _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
