linux-kernel - Re: [PATCH 1/6] drm/bridge: aux-hpd: fix OF node leaks

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Message-ID: <4938592e-3f7c-c1ae-dce3-fd1ca363296@inria.fr>
Date: Tue, 20 Feb 2024 13:56:32 +0100 (CET)
From: Julia Lawall <julia.lawall@...ia.fr>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
cc: Johan Hovold <johan@...nel.org>, Markus Elfring <Markus.Elfring@....de>, 
    Johan Hovold <johan+linaro@...nel.org>, freedreno@...ts.freedesktop.org, 
    dri-devel@...ts.freedesktop.org, linux-phy@...ts.infradead.org, 
    linux-arm-msm@...r.kernel.org, kernel-janitors@...r.kernel.org, 
    Andrzej Hajda <andrzej.hajda@...el.com>, 
    Bjorn Andersson <andersson@...nel.org>, Daniel Vetter <daniel@...ll.ch>, 
    David Airlie <airlied@...il.com>, 
    Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
    Maxime Ripard <mripard@...nel.org>, 
    Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
    Thomas Zimmermann <tzimmermann@...e.de>, Vinod Koul <vkoul@...nel.org>, 
    LKML <linux-kernel@...r.kernel.org>, 
    Abhinav Kumar <quic_abhinavk@...cinc.com>, 
    Jernej Skrabec <jernej.skrabec@...il.com>, Jonas Karlman <jonas@...boo.se>, 
    Kishon Vijay Abraham I <kishon@...nel.org>, 
    Konrad Dybcio <konrad.dybcio@...aro.org>, 
    Kuogee Hsieh <quic_khsieh@...cinc.com>, 
    Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
    Rob Clark <robdclark@...il.com>
Subject: Re: [PATCH 1/6] drm/bridge: aux-hpd: fix OF node leaks



On Tue, 20 Feb 2024, Dmitry Baryshkov wrote:

> On Tue, 20 Feb 2024 at 13:52, Julia Lawall <julia.lawall@...ia.fr> wrote:
> >
> >
> >
> > On Tue, 20 Feb 2024, Johan Hovold wrote:
> >
> > > On Mon, Feb 19, 2024 at 06:48:30PM +0100, Markus Elfring wrote:
> > > > > The two device node references taken during allocation need to be
> > > > > dropped when the auxiliary device is freed.
> > > > …
> > > > > +++ b/drivers/gpu/drm/bridge/aux-hpd-bridge.c
> > > > …
> > > > > @@ -74,6 +75,8 @@ struct device *drm_dp_hpd_bridge_register(struct device *parent,
> > > > >
> > > > >   ret = auxiliary_device_init(adev);
> > > > >   if (ret) {
> > > > > +         of_node_put(adev->dev.platform_data);
> > > > > +         of_node_put(adev->dev.of_node);
> > > > >           ida_free(&drm_aux_hpd_bridge_ida, adev->id);
> > > > >           kfree(adev);
> > > > >           return ERR_PTR(ret);
> > > >
> > > > The last two statements are also used in a previous if branch.
> > > > https://elixir.bootlin.com/linux/v6.8-rc5/source/drivers/gpu/drm/bridge/aux-hpd-bridge.c#L63
> > > >
> > > > How do you think about to avoid such a bit of duplicate source code
> > > > by adding a label here?
> > >
> > > No, the current code is fine and what you are suggesting is in any case
> > > unrelated to this fix.
> > >
> > > If this function ever grows a third error path like that, I too would
> > > consider it however.
> >
> > I guess these of_node_puts can all go away shortly with cleanup anyway?
>
> I'm not sure about it. Those are long-living variables, so they are
> not a subject of cleanup.h, are they?

OK, I didn't look at this code in detail, but cleanup would just call
of_node_put, not actually free the data.

julia