linux-kernel - Re: [PATCH 4/5] regulator: of: add missing of_node

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Message-ID: <alpine.DEB.2.10.1510121439440.2652@hadrien>
Date:	Mon, 12 Oct 2015 14:44:31 +0200 (CEST)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
cc:	Liam Girdwood <lgirdwood@...il.com>,
	kernel-janitors@...r.kernel.org, Mark Brown <broonie@...nel.org>,
	linux-kernel@...r.kernel.org,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Andrew Lunn <andrew@...n.ch>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Jason Cooper <jason@...edaemon.net>
Subject: Re: [PATCH 4/5] regulator: of: add missing of_node_put



On Mon, 12 Oct 2015, Krzysztof Kozlowski wrote:

> 2015-10-10 21:30 GMT+09:00 Julia Lawall <Julia.Lawall@...6.fr>:
> >
> > for_each_child_of_node performs an of_node_get on each iteration, so
> > a break out of the loop requires an of_node_put.
> >
> > The semantic patch that fixes this problem is as follows
> > (http://coccinelle.lip6.fr):
> >
> > // <smpl>
> > @@
> > expression root,e;
> > local idexpression child;
> > @@
> >
> >  for_each_child_of_node(root, child) {
> >    ... when != of_node_put(child)
> >        when != e = child
> > (
> >    return child;
> > |
> > +  of_node_put(child);
> > ?  return ...;
> > )
> >    ...
> >  }
> > // </smpl>
> >
> > Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>
> >
> > ---
> >  drivers/regulator/of_regulator.c |    1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/regulator/of_regulator.c b/drivers/regulator/of_regulator.c
> > index 499e437..f9d77b4 100644
> > --- a/drivers/regulator/of_regulator.c
> > +++ b/drivers/regulator/of_regulator.c
> > @@ -274,6 +274,7 @@ int of_regulator_match(struct device *dev, struct device_node *node,
> >                                 dev_err(dev,
> >                                         "failed to parse DT for regulator %s\n",
> >                                         child->name);
> > +                               of_node_put(child);
>
> This looks good.
>
> >                                 return -EINVAL;
> >                         }
> >                         match->of_node = of_node_get(child);
>
> But what about 'break' few lines below? The reference from last
> of_get_next_child() should be also dropped because... or we should
> remove this of_node_get() call.

Actually, the break is OK.  It's on the inner for loop, not the
for_each_child_of_node loop.  The for_each_child_of_node will still
decrement the reference count in the normal way.

julia

> How about fixing also usage of for_each_available_child_of_node() in
> regulator_of_get_init_data()?
>
> Best regards,
> Krzysztof
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