linux-kernel - Re: [PATCH v3] gpu: cdns-mhdp8546: fix call balance of mhdp->clk handling routines

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Message-ID: <kwrxxcjgjqvkwapfb7hrytf32ike3wqptjkr7mm3m4rz56xifi@ahbrdjt4cytk>
Date: Fri, 14 Feb 2025 18:02:35 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Vitalii Mordan <mordan@...ras.ru>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.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>, 
	Sui Jingfeng <sui.jingfeng@...ux.dev>, Aleksandr Mishin <amishin@...rgos.ru>, 
	Al Viro <viro@...iv.linux.org.uk>, Tomi Valkeinen <tomi.valkeinen@...com>, 
	Jyri Sarha <jsarha@...com>, Quentin Schulz <quentin.schulz@...e-electrons.com>, 
	Swapnil Jakhade <sjakhade@...ence.com>, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	Fedor Pchelkin <pchelkin@...ras.ru>, Alexey Khoroshilov <khoroshilov@...ras.ru>, 
	Vadim Mutilin <mutilin@...ras.ru>, lvc-project@...uxtesting.org
Subject: Re: [PATCH v3] gpu: cdns-mhdp8546: fix call balance of mhdp->clk
 handling routines

On Fri, Feb 14, 2025 at 06:46:32PM +0300, Vitalii Mordan wrote:
> If the clock mhdp->clk was not enabled in cdns_mhdp_probe(), it should not
> be disabled in any path.
> 
> The return value of clk_prepare_enable() is not checked. If mhdp->clk was
> not enabled, it may be disabled in the error path of cdns_mhdp_probe()
> (e.g., if cdns_mhdp_load_firmware() fails) or in cdns_mhdp_remove() after
> a successful cdns_mhdp_probe() call.
> 
> Use the devm_clk_get_enabled() helper function to ensure proper call
> balance for mhdp->clk.
> 
> Found by Linux Verification Center (linuxtesting.org) with Klever.
> 
> Fixes: fb43aa0acdfd ("drm: bridge: Add support for Cadence MHDP8546 DPI/DP bridge")
> Signed-off-by: Vitalii Mordan <mordan@...ras.ru>
> ---
> v2: Use devm_clk_get_enabled() helper function, as per Dmitry Baryshkov's
> request.
> v3: Describe the paths that lead to unbalanced clock handling routines,
> as requested by Dmitry Baryshkov
> 
>  drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

-- 
With best wishes
Dmitry