Re: [PATCH 1/3] of: base: add support to get machine compatible string

[Sudeep Holla]

Hi Sekhar,

On 22/11/16 15:06, Sekhar Nori wrote:
> Hi Sudeep,
>
> On Tuesday 22 November 2016 04:23 PM, Sudeep Holla wrote:
> > On 22/11/16 10:41, Bartosz Golaszewski wrote:
> > > Add a function allowing to retrieve the compatible string of the root
> > > node of the device tree.
> >
> > Rob has queued [1] and it's in -next today. You can reuse that if you
> > are planning to target this for v4.11 or just use open coding in your
> > driver for v4.10 and target this move for v4.11 to avoid cross tree
> > dependencies as I already mentioned in your previous thread.
>
> I dont have your original patch in my mailbox, but I wonder if
> returning a pointer to property string for a node whose reference has
> already been released is safe to do? Probably not an issue for the root
> node, but still feels counter-intuitive.

I am not sure if I understand the issue here. Are you referring a case
where of_root is freed ?

Also I have seen drivers today just using this pointer directly, but
it's better to copy the string(I just saw this done in one case)

> This is the code for reference:
>
> +int of_machine_get_model_name(const char **model)
> +{
> +       int error;
> +
> +       if (!of_node_get(of_root))
> +               return -EINVAL;
> +
> +       error = of_property_read_string(of_root, "model", model);
> +       if (error)
> +               error = of_property_read_string_index(of_root, "compatible",
> +                                                     0, model);
> +       of_node_put(of_root);
> +
> +       return error;
> +}
> +EXPORT_SYMBOL(of_machine_get_model_name);
>
> Thanks,
> Sekhar

--
Regards,
Sudeep