Re: [PATCH 2/4] PCI: kirin: Don't put .remove callback in .exit.text section

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Oct 03, 2023 at 10:23:30PM +0200, Uwe Kleine-König wrote:
> On Tue, Oct 03, 2023 at 12:15:24PM +0200, Uwe Kleine-König wrote:
> > On Mon, Oct 02, 2023 at 05:12:18PM -0500, Bjorn Helgaas wrote:
> > > On Sun, Oct 01, 2023 at 07:02:52PM +0200, Uwe Kleine-König wrote:
> > > > With CONFIG_PCIE_KIRIN=y and kirin_pcie_remove() marked with __exit, the
> > > > function is discarded from the driver. In this case a bound device can
> > > > still get unbound, e.g via sysfs. Then no cleanup code is run resulting
> > > > in resource leaks or worse.
> > > 
> > > kirin_pcie_driver sets .suppress_bind_attrs = true.
> > > 
> > > Doesn't that mean that we can't unbind a device via sysfs in this
> > > case?
> > 
> > Oh indeed, that's something I missed.
> >  
> > > I don't expect modpost to know about .suppress_bind_attrs, so maybe we
> > > should remove the __exit annotation even if it would be safe to keep
> > > it in this case.  It's a tiny function anyway.
> > 
> > the right thing to do then is something like:
> > https://lore.kernel.org/linux-rtc/20231002080529.2535610-7-u.kleine-koenig@pengutronix.de
> > 
> > And then it would be consequent to also switch to
> > module_platform_driver_probe and move .probe to __init. Or drop
> > .suppress_bind_attrs and keep/put .probe() and .remove() in .text.
> 
> The other three patches in this series don't suffer from this oversight
> and so are (from my POV) ready to go in.

Agreed.  My first impression was that this would be v6.7 material, but
based on
https://lore.kernel.org/linux-kbuild/CAK7LNATyRg6Hc-fnTETERj-tdMFGaBDt0Fyhy9+jKCzAvzQ6Pg@mail.gmail.com/,
I guess that modpost change must be headed for v6.6?

And while I haven't seen problem reports, branching into the weeds
because of a sysfs "remove" would be a pretty bad outcome, so I can
see a case for v6.6 and stable tags as well.  Is that your thought
process, too?

> If you tell me, which option you prefer for the kirin driver, I'll
> follow up with a matching patch. (If you don't know, my preference would
> be to drop .suppress_bind_attrs and move .probe() and .remove() to
> .text.)

I agree, dropping .suppress_bind_attrs would be desirable, although I
would hope for some kind of assurance that it's not there because of
an issue with removal or something.

Bjorn