# Re: \[PATCH\] firmware: arm\_scmi: Make scmi core independent of transport type

- From: Viresh Kumar \<viresh.kumar@linaro.org\>
- Date: 2020-01-09 09:16:19 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2020/01/5825322
- Thread: https://ratatoskr.run/linux-arm-kernel/2019/11/5791595/t.md

```text
On 09-01-20, 09:18, Arnd Bergmann wrote:
> > +static int mailbox_chan_free(int id, void *p, void *data)
> > +{
> > +       struct scmi_chan_info *cinfo = p;
> > +       struct scmi_mailbox *smbox = cinfo->transport_info;
> > +
> > +       if (!IS_ERR_OR_NULL(smbox->chan)) {
> > +               mbox_free_channel(smbox->chan);
> > +               cinfo->transport_info = NULL;
> > +               smbox->chan = NULL;
> > +               smbox->cinfo = NULL;
> > +       }
> 
> There is something wrong if smbox->chan can be be one of
> three things (a valid pointer, a NULL pointer, or an error value).
> 
> I see this is a preexisting problem, but please add a patch to
> make it consistently use either NULL pointers or error codes
> and remove all instances of IS_ERR_OR_NULL() from this
> subsystem.

This isn't a subsystem problem actually. mbox_request_channel() never
returns NULL on error.

@Sudeep, do we really need the IS_ERR_OR_NULL() check in
scmi_mbox_free_channel() helper ? Or can it just be IS_ERR() ?

-- 
viresh

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