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

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Date: Tue, 20 Feb 2024 08:24:55 +0100
From: Johan Hovold <johan@...nel.org>
To: Markus Elfring <Markus.Elfring@....de>
Cc: 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>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	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 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.

Johan