bug#67132: closed ([Shepherd] Bogus value from PID file can prevent service from being stopped)

[GNU bug Tracking System]

Your message dated Wed, 22 Nov 2023 11:16:37 +0100
with message-id <87fs0ym6t6.fsf@gnu.org>
and subject line Re: bug#67132: [Shepherd] Bogus value from PID file can 
prevent service from being stopped
has caused the debbugs.gnu.org bug report #67132,
regarding [Shepherd] Bogus value from PID file can prevent service from being 
stopped
to be marked as done.

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67132: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=67132
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> --- Begin Message ---
>
>
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> Subject: 
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> [Shepherd] Bogus value from PID file can prevent service from being stopped
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> Date: 
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> Sun, 12 Nov 2023 18:45:38 +0100
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> User-agent: 
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> Gnus/5.13 (Gnus v5.13)
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>
>
>
> Hi,
>
> ‘terminate-process’ in (shepherd service) assumes that, once it has sent
> SIGKILL to a given PID, it eventually gets a SIGCHLD notification for
> that PID.
>
> Unfortunately there are corner cases where it doesn’t hold.  Take PID 2:
>
> --8<---------------cut here---------------start------------->8---
> $ ps x 2
>   PID TTY      STAT   TIME COMMAND
>     2 ?        S      0:00 [kthreadd]
> --8<---------------cut here---------------end--------------->8---
>
> That’s not a “real” process, so when you (kill 2 SIGKILL), nothing
> happens.  Thus, ‘terminate-process’ never returns; the corresponding
> service stays in “stopping” state and you cannot halt your machine.
>
> You may wonder how we end up calling ‘terminate-process’ with a “bogus”
> PID.  It normally never happens, but it can happen with a combination of
> ‘make-forkexec-constructor’ with #:pid-file and
> ‘least-authority-wrapper’: the PID file of the wrapper may read “2” (the
> PID inside the least-authority PID namespace), so ‘herd stop’ on that
> service will end up doing (kill 2 SIGKILL).
>
> Ludo’.
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#67132: [Shepherd] Bogus value from PID file can prevent service from being stopped
>
>
>
>
> Date: 
>
> Wed, 22 Nov 2023 11:16:37 +0100
>
>
>
>
> User-agent: 
>
> Gnus/5.13 (Gnus v5.13)
>
>
>
>
> Ludovic Courtès <ludo@gnu.org> skribis:
>
> > ‘terminate-process’ in (shepherd service) assumes that, once it has sent
> > SIGKILL to a given PID, it eventually gets a SIGCHLD notification for
> > that PID.
> >
> > Unfortunately there are corner cases where it doesn’t hold.  Take PID 2:
> >
> > $ ps x 2
> >   PID TTY      STAT   TIME COMMAND
> >     2 ?        S      0:00 [kthreadd]
> >
> > That’s not a “real” process, so when you (kill 2 SIGKILL), nothing
> > happens.  Thus, ‘terminate-process’ never returns; the corresponding
> > service stays in “stopping” state and you cannot halt your machine.
>
> Fixed in Shepherd commit cc9c5c029534458ae547d78200b6b51f729654e3.
>
> Ludo’.
>
>
> --- End Message ---