Re: [PATCH] PM / wakeup: Allocate class wakeup_class statically

Rafael J. Wysocki
2026-04-03T10:45:59Z

On Thu, Apr 2, 2026 at 3:05 PM Heiner Kallweit <hkallweit1@gmail.com> wrote:
>
> On 01.04.2026 19:32, Rafael J. Wysocki wrote:
> > On Wed, Apr 1, 2026 at 5:45 PM Heiner Kallweit <hkallweit1@gmail.com> wrote:
> >>
> >> On 01.04.2026 16:19, Rafael J. Wysocki wrote:
> >>> On Sun, Mar 29, 2026 at 6:14 PM Heiner Kallweit <hkallweit1@gmail.com> wrote:
> >>>>
> >>>> Allocating wakeup_class statically avoids a little runtime overhead.
> >>>> Define groups and device release function as part of the class, so that
> >>>> we don't have to repeat this for each class device.
> >>>> Whilst at it, constify wakeup_source_attrs[].
> >>>>
> >>>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> >>>
> >>> Can you please have a look at this and let me know what you think:
> >>>
> >>> https://sashiko.dev/#/patchset/0fe1b679-ab28-4505-b0db-14e7ac3ba749%40gmail.com
> >>>
> >> Interesting finding! I think the diagnosis is right.
> >>
> >> But: I would say the current behavior isn't a nice solution as well:
> >
> > It is not fantastic, but it doesn't have this issue.
> >
> >> wakeup_source_device_create() does: dev->class = wakeup_class;
> >> I think no reader will expect that wakeup_class may be NULL here due to
> >> initcall ordering. In addition this behavior results in such early
> >> wakeup sources not being shown in sysfs.
> >
> > They are registered too early to show up in sysfs, but they can work regardless.
> >
> > I think that it's just pointless to call device_register() for a given
> > wakeup source if wakeup_class has not been registered yet.
> >
> >> But I'm not sure whether registering class "wakeup" (and registering
> >> classes in general) would be possible early enough (core_initcall,
> >> or even pure_initcall).
> >
> > driver_init() is called before do_initcalls() is do_basic_setup(), so
> > class registration should work for all initcall levels AFAICS.
> >
> When testing the current code on my system, autosleep is the first wakeup
> source, registered in a core_initcall, and it's not shown in sysfs.
> Same result when class wakeup is registered in a core_initcall
> (instead of postcore_initcall). Registering class wakeup in a pure_initcall
> works and fixes the issue. So, would this be an acceptable solution for the
> discussed issue?

I don't see why not.