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Date: Mon, 29 Jun 2026 06:35:48 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: WenTao Liang <vulab@iscas.ac.cn>
Cc: maarten.lankhorst@linux.intel.com, mripard@kernel.org,
	tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch,
	kees@kernel.org, dmitry.baryshkov@oss.qualcomm.com,
	tomi.valkeinen@ideasonboard.com, mcanal@igalia.com,
	suraj.kandpal@intel.com, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2] drm/display: fix MST branch device refcount leak on
 DPCD write failure
Message-ID: <2026062906-bonding-pointless-f53d@gregkh>
References: <20260628133344.46188-1-vulab@iscas.ac.cn>
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In-Reply-To: <20260628133344.46188-1-vulab@iscas.ac.cn>

On Sun, Jun 28, 2026 at 09:33:44PM +0800, WenTao Liang wrote:
> drm_dp_add_mst_branch_device initializes mstb with refcount 1, and
> drm_dp_mst_topology_get_mstb increments it to 2. When
> drm_dp_dpcd_write_byte fails, out_unlock performs only one
> drm_dp_mst_topology_put_mstb, leaving the other reference stored in
> mgr->mst_primary. Since MST was not successfully enabled, no disable path
> will clean it up.
> 
> Suggested-by: Greg KH <gregkh@linuxfoundation.org>

I did?  Where did I do that?

> Fixes: 7a3cbf590e63 ("drm/mst: Some style improvements in drm_dp_mst_topology_mgr_set_mst()")
> Cc: stable@vger.kernel.org
> Signed-off-by: WenTao Liang <vulab@iscas.ac.cn>

Again, you need to document the tools you used to find/fix this with
assisted-by, right?  Please read our documentation for when you use
LLMs.

thanks,

greg k-h