linux-kernel - Re: [PATCH] drm/display: hdmi-cec-helper: Fix adapter unregistration

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Message-ID: <ueibew6g6shgvu3gjwlvrbh2zlaqmablud74yzkwv3zsr55jw7@ydt27epp3miq>
Date: Fri, 4 Jul 2025 00:31:42 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
Cc: 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>,
        kernel@...labora.com, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/display: hdmi-cec-helper: Fix adapter unregistration

On Thu, Jul 03, 2025 at 11:05:45PM +0300, Cristian Ciocaltea wrote:
> Attempting to reload a kernel module of an HDMI driver making use of the
> new CEC helpers revealed a resource deallocation issue, i.e. the entries
> in /dev/cec* keep growing.
> 
> Moreover, after a couple of tries the kernel crashes and the whole
> system freezes:
> 
> [   47.515950] Unable to handle kernel paging request at virtual address 0020072007200778
> [...]
> [   47.521707] Internal error: Oops: 0000000096000004 [#1]  SMP
> [...]
> [   47.537597] Call trace:
> [   47.537815]  klist_next+0x20/0x1b8 (P)
> [   47.538152]  device_reorder_to_tail+0x74/0x120
> [   47.538548]  device_reorder_to_tail+0x6c/0x120
> [   47.538944]  device_pm_move_to_tail+0x78/0xd0
> [   47.539334]  deferred_probe_work_func+0x9c/0x110
> [   47.539747]  process_one_work+0x328/0x638
> [   47.540108]  worker_thread+0x264/0x390
> [   47.540445]  kthread+0x20c/0x230
> [   47.540735]  ret_from_fork+0x10/0x20
> 
> Do a proper cleanup by calling cec_unregister_adapter() instead of
> cec_delete_adapter() in the managed release action handler.
> 
> Fixes: 8b1a8f8b2002 ("drm/display: add CEC helpers code")
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
> ---
>  drivers/gpu/drm/display/drm_hdmi_cec_helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>


-- 
With best wishes
Dmitry