when shutdown hangs, automatically show some helpful information

[Code7R]

Hi,

this is a repost of https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=792761 , see there for details. And for demonstration, see https://www.unix-ag.uni-kl.de/~bloch/part2.m4v .

Short summary: AFAICS currently the user only one proper way to debug an endless loop on shutdown time, and this also needs to be set up before and also opens a security hole. So that's not a proper solution for randomly appearing problems on a production system.

What I imagine is something like following:

• after 10 seconds of pointless trying, start displaying more details (like full unit name of the hanging processes)
• after 20 seconds display even more details
• after 30 seconds, show the user a message that he can interrupt something somehow. Maybe kill a random hanging task pressing Ctrl-Alt-Del or something (I don't have the expert knowledge here).

And the last thing it should do is reacting to CAD by starting and stopping some unrelated units, that looks totally wrong.

[poettering]

Note that there's already a logic in place to expedite shutdown if you press C-A-D more than 7x within 2s.

But yeah, we might want to show information about the hanging shutdown automatically, too.