Re: [Xen-devel] [PATCH 03/44] hibernate: Call have_kernel_poweroff instead of checking pm_power_off

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On 10/09/2014 03:32 AM, Pavel Machek wrote:
> On Mon 2014-10-06 22:28:05, Guenter Roeck wrote:
> > Poweroff handlers may now be installed with register_poweroff_handler.
> > Use the new API function have_kernel_poweroff to determine if a poweroff
> > handler has been installed.
> >
> > Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
> > Cc: Pavel Machek <pavel@xxxxxx>
> > Cc: Len Brown <len.brown@xxxxxxxxx>
> > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > ---
> >   kernel/power/hibernate.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> > index a9dfa79..20353c5 100644
> > --- a/kernel/power/hibernate.c
> > +++ b/kernel/power/hibernate.c
> > @@ -602,7 +602,7 @@ static void power_down(void)
> >         case HIBERNATION_PLATFORM:
> >                 hibernation_platform_enter();
> >         case HIBERNATION_SHUTDOWN:
> > -               if (pm_power_off)
> > +               if (have_kernel_poweroff())
> >                         kernel_power_off();
> >                 break;
> poweroff -> power_off.
As mentioned in my other reply, that was on purpose to distinguish
existing functions from poweroff handler functions.

> But if you are playing with this, anyway... does it make sense to
> introduce kernel_power_off() that just works, no need to check
> have_..?
>                                                                         Pavel
I am trying not to change existing behavior.

kernel_power_off is an existing function which does some cleanup
before calling machine_power_off which in turn calls do_kernel_poweroff
(or currently pm_power_off and may do some other machine specific stuff.

Sure, poweroff handling could be unified further. We could decide to
enter an endless loop if machine_power_off() returns, or we could decide
to dump a warning or panic in this case. But that is all separate from
the issue I am trying to solve here, which is to provide a capability to
register more than one poweroff handler. It would also not be that simple,
since some architectures call machine_power_off() directly from various
places.

Guenter


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