linux-kernel - Re: [PATCH] leds: lp50xx: Fix an error handling path in 'lp50xx_probe

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Message-ID: <faa49efc-5ba5-b6bd-b486-2f7c4611219b@wanadoo.fr>
Date:   Wed, 23 Sep 2020 20:49:56 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     pavel@....cz, dmurphy@...com, jacek.anaszewski@...il.com,
        linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] leds: lp50xx: Fix an error handling path in
 'lp50xx_probe_dt()'

Le 23/09/2020 à 15:35, Dan Carpenter a écrit :
> I've added Heikki Krogerus to the CC list because my question is mostly
> about commit 59abd83672f7 ("drivers: base: Introducing software nodes to
> the firmware node framework").
> 
> 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.

CJ