Re: [PATCH] amba: make amba_bustype constant

Andy Shevchenko
2024-08-26T10:40:24Z

On Mon, Aug 26, 2024 at 06:08:11PM +0800, Kunwu Chan wrote:
> On 2024/8/23 21:48, Andy Shevchenko wrote:
> > On Fri, Aug 23, 2024 at 02:42:03PM +0800, Kunwu Chan wrote:

...

> > > -extern struct bus_type amba_bustype;
> > > +extern const struct bus_type amba_bustype;
> > Can we actually hide this from the outside, i.e. make it static in the C file,
> > and introduce the dev_is_amba() helper instead?
> >
> > P.S. You may look at the PNP bus case (some of the latest patches there)
>
> I found it problematic in the process of making changes.
>
> There have some usage of amba_bustype outside the AMBA code ,i.e:
> https://elixir.bootlin.com/linux/v6.10.4/source/drivers/iommu/iommu.c#L155
>
> So, If we make the amba_bustype inside the AMBA code, the outside cannot
> access.

Yes, that's the idea.

> If only internal access is allowed, it will compile and report an error, how
> should I modify it next, and any suggestions?

Make it patch series:
1) patch that introduces exported function called dev_is_amba() (1 patch);
2) convert user-by-user (N patches);
3) hide the bus type and make it constant.

--
With Best Regards,
Andy Shevchenko