Re: [PATCH] xen/domain: make shutdown state explicit

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

Hi Michal,

Thank you for the review.

On Thu, Mar 19, 2026 at 12:09 PM Orzel, Michal <michal.orzel@xxxxxxx> wrote:
>
>
>
> On 19/03/2026 00:25, Mykola Kvach wrote:
> > From: Mykola Kvach <mykola_kvach@xxxxxxxx>
> >
> > The domain shutdown flow currently overloads is_shutting_down and
> > is_shut_down to represent multiple phases of the shutdown lifecycle,
> > while some users treat is_shutting_down as a broader "domain is no
> > longer normal" condition.
> >
> > Make the shutdown lifecycle explicit by introducing
> > enum domain_shutdown_state and converting the existing users to helper
> > predicates describing whether shutdown is in progress, complete, or
> > active.
> >
> > At the same time, make domain_resume() validate its input state and
> > return an error to its callers. Resume is now accepted only from the
> > fully shut down state.
> Also, you limit it now to SHUTDOWN_suspend or SHUTDOWN_soft_reset. Ideally you
> should explain why i.e. resuming from crash/poweroff/reboot is semantically
> meaningless.

That makes sense. Looking at the existing flow more closely, the
suspend and soft-reset cases are not symmetric.

For suspend, the intended semantics are explicit and long-standing:
the public SCHEDOP_shutdown documentation describes special resume
semantics only for SHUTDOWN_suspend, libxl documents resume for a
suspended domain, and xc_domain_resume has long rejected domains
which are not shut down with SHUTDOWN_suspend.

Soft reset is different. The toolstack may choose soft-reset as the
action for other shutdown reasons too, e.g. on_reboot=soft-reset.
In that case the domain reaches the soft-reset path with
shutdown_code still set to SHUTDOWN_reboot, and only afterwards the
toolstack decides to perform a soft reset. So the new validation in
domain_resume() is too strict for the existing soft-reset flow.

Given that, I agree the checks should not be there in the current
form.

I'll drop the checks in the next version.

Best regards,
Mykola

>
> >
> > This removes the implicit coupling between unrelated users of
> > is_shutting_down and makes the shutdown/resume state transitions
> > self-describing.
> >
> > Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
> > Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
> This is mostly a mechanical change. I verified that correct helpers are used 
> in
> place of old flags.
> Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
>
> ~Michal
>