[systemd-devel] Allow stop jobs to be killed during shutdown

[Tom Gundersen]

On Mon, Jan 27, 2014 at 7:43 AM, Zbigniew Jędrzejewski-Szmek
<zbyszek at in.waw.pl> wrote:
> On Sun, Jan 26, 2014 at 09:16:13PM +0400, Andrey Borzenkov wrote:
>> В Sun, 26 Jan 2014 17:23:54 +0100
>> Tom Gundersen <teg at jklm.no> пишет:
>>
>> >
>> > >> Unfortunately, setting KillMode=process is not allowed:
>> > >>
>> > >> Jan 26 17:12:30 linux-1a7f systemd[1]: user at 0.service has PAM enabled. Kill mode must be set to 'control-group'. Refusing.
>> > >>
>> > >> Probably user at .service should be exempt from this rule. It is supposed
>> > >> to handle all services started by it itself, it *is* service manager
>> > >> after all?
>> >
>> > I don't think we want any processes to survive the exit of
>> > user at .service, so KillMode=process feels wrong. However, isn't the
>> > problem that we are going into the "kill control-group" mode too soon,
>> > before user at .serivce has had a chance of cleaning itself up
>> > gracefully?
>> >
>>
>> Yes.
>>
>> > > I rebuilt systemd without this restriction, set KillMode=process for
>> > > user at .service and this fixed things here.
>> > >
>> > > So there are two problems associated with user instance.
>> > >
>> > > 1. Using KillMode=control-group is wrong. Each service managed by user
>> > > instance has own requirements how it is stopped. Just sending everything
>> > > SIGTERM without even trying service ExecStop first is obviously
>> > > incorrect.
>> >
>> > I guess what we want is to first send SIGTERM only to the systemd
>> > --user process, and only after a timeout start sending SIGTERM to all
>> > the processes in the control group? I.e., wouldn't a ExecStop entry in
>> > user at .service give us the required timeout?
>> >
>>
>> Does not work. systemd sends SIGTERM as soon as ExecStop finished.
> Looks like we need a setting like SendKillSignalTo=main-pid|all|control-pid.
> Or something like that.
>
> Also the TimeoutStopSec on user at .service should be probably increased
> to 10 min or so.
>
>> I believe someone already mentioned this problem. In general, we cannot
>> assume that ExecStop is synchronous. It may just signal main process to
>> exit. systemd should wait until $MAINPID exits (or timeout) before
>> continuing further processing.
> ExecStop is required to be synchronous, i.e. the service should be stopped
> when it returns. /bin/kill is not going to work here.

Good point, I had missed that (I assumed there was a timeout). So
something like a synchronous "systemctl --user stop" should do it, no?

-t