Re: [PATCH v2] hisi_lpc: Use acpi_dev_for_each_child()

[John Garry]

On 30/06/2022 13:48, Rafael J. Wysocki wrote:
> On Wed, Jun 29, 2022 at 3:47 PM Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > Instead of walking the list of children of an ACPI device directly,
> > use acpi_dev_for_each_child() to carry out an action for all of
> > the given ACPI device's children.
> >
> > This will help to eliminate the children list head from struct
> > acpi_device as it is redundant and it is used in questionable ways
> > in some places (in particular, locking is needed for walking the
> > list pointed to it safely, but it is often missing).
>
> I've overlooked another usage of the children list in hisi_lpc, in
> hisi_lpc_acpi_probe(), and eliminating that one is a bit more
> complicated.
>
> So please scratch this one and I will send a v3 when 0-day tells me
> that it builds.

Hi Rafael,

If it makes things simpler then I can just fix the driver so that we 
can't unload it. Let me know if that suits better.

Cheers

> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> > Acked-by: John Garry <john.garry@xxxxxxxxxx>
> > ---
> >
> > -> v2:
> >     * Drop unused local variable (John).
> >     * Add ACK from John.
> >
> > ---
> >   drivers/bus/hisi_lpc.c |   14 ++++++++------
> >   1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > Index: linux-pm/drivers/bus/hisi_lpc.c
> > ===================================================================
> > --- linux-pm.orig/drivers/bus/hisi_lpc.c
> > +++ linux-pm/drivers/bus/hisi_lpc.c
> > @@ -471,6 +471,12 @@ static int hisi_lpc_acpi_remove_subdev(s
> >          return 0;
> >   }
> >
> > +static int hisi_lpc_acpi_clear_enumerated(struct acpi_device *adev, void *not_used)
> > +{
> > +       acpi_device_clear_enumerated(adev);
> > +       return 0;
> > +}
> > +
> >   struct hisi_lpc_acpi_cell {
> >          const char *hid;
> >          const char *name;
> > @@ -480,13 +486,9 @@ struct hisi_lpc_acpi_cell {
> >
> >   static void hisi_lpc_acpi_remove(struct device *hostdev)
> >   {
> > -       struct acpi_device *adev = ACPI_COMPANION(hostdev);
> > -       struct acpi_device *child;
> > -
> >          device_for_each_child(hostdev, NULL, hisi_lpc_acpi_remove_subdev);
> > -
> > -       list_for_each_entry(child, &adev->children, node)
> > -               acpi_device_clear_enumerated(child);
> > +       acpi_dev_for_each_child(ACPI_COMPANION(hostdev),
> > +                               hisi_lpc_acpi_clear_enumerated, NULL);
> >   }
> >
> >   /*
> .