[PATCH 01/20] mtd: rawnand: txx9ndfmc: Mark driver struct with __refdata to prevent section mismatch warning

[Uwe Kleine-König]

Hello,

[Changed email address for David Woodhouse from intel to infradead]

On Mon, Oct 09, 2023 at 10:43:46AM +0200, Arnd Bergmann wrote:
> On Mon, Oct 9, 2023, at 09:22, Masahiro Yamada wrote:
> > On Mon, Oct 9, 2023 at 5:02 AM Uwe Kleine-König <u.kleine-koenig at pengutronix.de> wrote:
> >>
> >> As described in the added code comment, a reference to .exit.text is ok
> >> for drivers registered via module_platform_driver_probe(). Make this
> >> explicit to prevent a section mismatch warning with
> 
> >
> > We have thousands of module_platform_drivers.
> > I would be scared if they started to add __refdata.
> >
> > I am not sure if this is the right direction.
> 
> For a normal module_platform_driver(), this would indeed be
> wrong, but as Uwe said above there is a special case for
> module_platform_driver_probe(), which implicitly sets the
> drv->driver.suppress_bind_attrs=true flag.
> 
> > In my understanding of the current DT overlay,
> > there is no way to create/remove a platform device dynamically.
> > I do not know if that will happen in the future.
> 
> For drivers without suppress_bind_attrs, you can manually
> unbind the device from a driver, which in case of a loadable
> module ends up calling the .remove callback (this is fine),
> but in a built-in driver this would use a NULL pointer for
> .remove and cause unexpected behavior.

only a slight correction: As not having a remove callback can be fine
and platform_remove() only calls .remove (or .remove_new) when non-NULL
we're not hitting a NULL pointer dereference in the presence of

	.remove = __exit_p(somefunc),

But a problem can arise later if some resource isn't properly freed and
so it might be used at a later point in time which then most likely
oopses.

I didn't double check Arnd's list, but otherwise I agree to his
analysis.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 488 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-mtd/attachments/20231009/61b4225c/attachment.sig>