Re: [PATCH v7 2/4] power: reset: add reboot mode driver

[Andy Yan]

Hi Krzysztof:

On 2016å04æ06æ 09:00, Krzysztof Kozlowski wrote:
> On 06.04.2016 09:50, Andy Yan wrote:
>
> (...)
>
> > > > +            return -ENOMEM;
> > > > +
> > > > +        info->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
> > > > +        if (of_property_read_u32(np, prop->name, &info->magic)) {
> > > > +            dev_err(dev, "reboot mode %s without magic number\n",
> > > > +                info->mode);
> > > > +            devm_kfree(dev, info);
> > > > +            continue;
> > > > +        }
> > > > +        list_add_tail(&info->list, &reboot->head);
> > > > +    }
> > > > +    of_node_put(np);
> > > If you of_node_put() here, there is no sense in getting it before. I
> > > mentioned of_node_get() only because I am not sure about life-cycle of
> > > nodes in case of DT overlays and you are storing the pointer to string
> > > from DT.
> > >
> > > The doubts I have are concerning only the case of freeing nodes from
> > > overlay.
> > >
> > > I don't know if of_node_get() is needed but of_node_get()+of_node_put()
> > > seems useless.
> >
> >   I am also not sure about it. Maybe just drop of_node_get/put ?
> OK, let's drop both get() and put().
>
> (...)
>
> > > > +
> > > > +static const struct of_device_id syscon_reboot_mode_of_match[] = {
> > > > +    { .compatible = "syscon-reboot-mode" },
> > > > +    {}
> > > > +};
> > > > +
> > > > +static struct platform_driver syscon_reboot_mode_driver = {
> > > > +    .probe = syscon_reboot_mode_probe,
> > > Cleanup needed. What will happen after device unbind? Memory will be
> > > released (devm-*()) but reboot notifier won't thus leading to OOPS on
> > > reboot.
> >      From the kernel_restart_prepare function, the reboot notifier will
> > be called before device_shutdown. Is there any other case the device
> > unbind before reboot notifier
> > called?
> This is a regular module platform driver so unbind can happen any time
> initiated by user, either by unbind command or by module removal. User
> can then re-bind device or not - probably does not matter. Anyway after
> such first unbind, the restart will kaboom instead of do a restart.

    I just need to do clean up in remove?
> Beside that, you always should clean up, regardless of restart or not.
> If you do not want unbind (thus no need of cleanup) then forbid it by
> making it a non-module with suppressed bind.
>
> Best regards,
> Krzysztof