linux-kernel - Re: [PATCH 1/4] regulator: qcom_spmi: Fix warning Bad of_node

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Message-ID: <20180716132931.GA866@centauri.lan>
Date:   Mon, 16 Jul 2018 15:29:31 +0200
From:   Niklas Cassel <niklas.cassel@...aro.org>
To:     Johan Hovold <johan@...nel.org>
Cc:     broonie@...nel.org, Liam Girdwood <lgirdwood@...il.com>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] regulator: qcom_spmi: Fix warning Bad of_node_put()

On Mon, Jul 16, 2018 at 02:01:34PM +0200, Johan Hovold wrote:
> Hi Niklas,
> 
> On Mon, Jul 16, 2018 at 01:35:22PM +0200, Niklas Cassel wrote:
> > For of_find_node_by_name(), you typically pass what the previous call
> > returned. Therefore, of_find_node_by_name() increases the refcount of
> > the returned node, and decreases the refcount of the node passed as the
> > first argument.
> > 
> > However, in this case we don't pass what the previous call returned,
> > so we have to increase the refcount of the first argument to compensate.
> 
> I don't think this is the right fix. of_find_node_by_name() should
> generally not be used by drivers in the first place as it searches the
> entire tree and can end up matching an entirely unrelated node.
> 
> I haven't looked at the device-tree binding in question, but you
> probably want to use something like of_get_child_by_name() instead.
> 

Hello Johan,

of_find_node_by_name() will only search the whole tree if the
first argument is NULL, which isn't the case here.

However, of_get_child_by_name() is indeed better suited here.
Will send out a v2.

Thank you for your feedback, it is much appreciated :)

Kind regards,
Niklas