Re: [PATCH] leds: lp50xx: Fix an error handling path in 'lp50xx_probe_dt()'

Heikki Krogerus
2020-11-25T12:17:03Z

On Wed, Nov 25, 2020 at 11:46:29AM +0100, Pavel Machek wrote:
> Hi!
>
> > > > > I have been trying to teach Smatch to understand reference counting so
> > > > > it can discover these kinds of bugs automatically.
> > > > >
> > > > > I don't know how software_node_get_next_child() can work when it doesn't
> > > > > call kobject_get(). This sort of bug would have been caught in testing
> > > > > because it affects the success path so I must be reading the code wrong.
> > > > >
> > > >
> > > > I had the same reading of the code and thought that I was missing something
> > > > somewhere.
> > > >
> > > > There is the same question about 'acpi_get_next_subnode' which is also a
> > > > '.get_next_child_node' function, without any ref counting, if I'm correct.
> > > >
> > >
> > > Yeah, but there aren't any ->get/put() ops for the acpi_get_next_subnode()
> > > stuff so it's not a problem. (Presumably there is some other sort of
> > > refcounting policy there).
> >
> > OK, so I guess we need to make software_node_get_next_child()
> > mimic the behaviour of of_get_next_available_child(), and not
> > acpi_get_next_subnode(). Does the attached patch work?
>
> Does not sound unreasonable. Did it get solved, somehow?

Has anybody tested my patch?

thanks,

--
heikki