linux-kernel - Re: [PATCH] phy: ti: j721e-wiz: Fix device_node leak in wiz_get_lane_phy

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Message-ID: <CAN4SLj2isLi3Hd4Zp7QV+PtYQPLzafo9DiD1Vza6+zLqq90u6Q@mail.gmail.com>
Date: Thu, 12 Feb 2026 02:47:35 +0800
From: Felix Gu <ustc.gu@...il.com>
To: Vladimir Oltean <olteanv@...il.com>
Cc: Vinod Koul <vkoul@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Kishon Vijay Abraham I <kishon@...nel.org>, Jyri Sarha <jsarha@...com>, linux-phy@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] phy: ti: j721e-wiz: Fix device_node leak in wiz_get_lane_phy_types()

On Wed, Feb 11, 2026 at 4:30 AM Vladimir Oltean <olteanv@...il.com> wrote:
>
> Hi Felix,
>
> On Wed, Feb 11, 2026 at 02:14:11AM +0800, Felix Gu wrote:
> > The 'serdes' device_node is obtained using of_get_child_by_name(),
> > which increments the reference count. However, it is never put,
> > leading to a memory leak.
> >
> > Use the __free(device_node) attribute to automatically decrement
> > the reference count when the 'serdes' variable goes out of scope.
> >
> > Fixes: 7ae14cf581f2 ("phy: ti: j721e-wiz: Implement DisplayPort mode to the wiz driver")
> > Signed-off-by: Felix Gu <ustc.gu@...il.com>
> > ---
> >  drivers/phy/ti/phy-j721e-wiz.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/phy/ti/phy-j721e-wiz.c b/drivers/phy/ti/phy-j721e-wiz.c
> > index 12a19bf2875c..904541e9138e 100644
> > --- a/drivers/phy/ti/phy-j721e-wiz.c
> > +++ b/drivers/phy/ti/phy-j721e-wiz.c
> > @@ -1407,9 +1407,8 @@ MODULE_DEVICE_TABLE(of, wiz_id_table);
> >
> >  static int wiz_get_lane_phy_types(struct device *dev, struct wiz *wiz)
> >  {
> > -     struct device_node *serdes;
> > -
> > -     serdes = of_get_child_by_name(dev->of_node, "serdes");
> > +     struct device_node *serdes __free(device_node) =
> > +             of_get_child_by_name(dev->of_node, "serdes");
> >       if (!serdes) {
> >               dev_err(dev, "%s: Getting \"serdes\"-node failed\n", __func__);
> >               return -EINVAL;
> >
> > ---
> > base-commit: 193579fe01389bc21aff0051d13f24e8ea95b47d
> > change-id: 20260204-wiz-9a67604a034f
> >
> > Best regards,
> > --
> > Felix Gu <ustc.gu@...il.com>
> >
> >
>
> You are fixing a bug from 2020 (v5.8) with functionality introduced in 2023,
> creating avoidable headache for backporters (the oldest supported LTS is
> 5.10, where the cleanup API does not exist). Could we reimplement this
> the "normal" of_node_put() way?
>
> I realize this is not netdev, but this piece of advice from
> Documentation/process/maintainer-netdev.rst regarding use in drivers
> seems common sense and relevant here:
>
>   Low level cleanup constructs (such as ``__free()``) can be used when building
>   APIs and helpers, especially scoped iterators. However, direct use of
>   ``__free()`` within networking core and drivers is discouraged.
>   Similar guidance applies to declaring variables mid-function.
Hi Vladimir,
I will fix it in V2.
Thanks,
Felix