linux-kernel - Re: [PATCH] drm: sti: fix device leaks at component probe

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Message-ID: <aQTtlvoe96Odq96A@thinkstation>
Date: Fri, 31 Oct 2025 18:10:46 +0100
From: Raphaël Gallais-Pou <rgallaispou@...il.com>
To: Johan Hovold <johan@...nel.org>
Cc: Alain Volmat <alain.volmat@...s.st.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org,
	Benjamin Gaignard <benjamin.gaignard@...labora.com>
Subject: Re: [PATCH] drm: sti: fix device leaks at component probe

Hi Johan, 

For some reason this thread went through my filters, sorry.

Le Mon, Sep 22, 2025 at 02:20:12PM +0200, Johan Hovold a écrit :
> Make sure to drop the references taken to the vtg devices by
> of_find_device_by_node() when looking up their driver data during
> component probe.

Markus suggested “Prevent device leak in of_vtg_find()” as commit
summary.

> 
> Note that holding a reference to a platform device does not prevent its
> driver data from going away so there is no point in keeping the
> reference after the lookup helper returns.
> 
> Fixes: cc6b741c6f63 ("drm: sti: remove useless fields from vtg structure")
> Cc: stable@...r.kernel.org	# 4.16
> Cc: Benjamin Gaignard <benjamin.gaignard@...labora.com>
> Signed-off-by: Johan Hovold <johan@...nel.org>
> ---
>  drivers/gpu/drm/sti/sti_vtg.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/sti/sti_vtg.c b/drivers/gpu/drm/sti/sti_vtg.c
> index ee81691b3203..ce6bc7e7b135 100644
> --- a/drivers/gpu/drm/sti/sti_vtg.c
> +++ b/drivers/gpu/drm/sti/sti_vtg.c
> @@ -143,12 +143,17 @@ struct sti_vtg {
>  struct sti_vtg *of_vtg_find(struct device_node *np)
>  {
>  	struct platform_device *pdev;
> +	struct sti_vtg *vtg;
>  
>  	pdev = of_find_device_by_node(np);
>  	if (!pdev)
>  		return NULL;
>  
> -	return (struct sti_vtg *)platform_get_drvdata(pdev);
> +	vtg = platform_get_drvdata(pdev);
> +
> +	put_device(&pdev->dev);

I would prefer of_node_put() instead, which does the same basically, but
at least it is more obviously linked to of_find_device_by_node().

Best regards,
Raphaël
> +
> +	return vtg;
>  }
>  
>  static void vtg_reset(struct sti_vtg *vtg)
> -- 
> 2.49.1
>