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Message-ID: <059e0a81-3c0a-1c8f-90f0-a836da1204f5@quicinc.com>
Date:   Fri, 10 Jun 2022 16:20:07 -0700
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Subject: Re: [PATCH] drm/msm/mdp4: Fix refcount leak in mdp4_modeset_init_intf
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To:     Miaoqian Lin <linmq006@gmail.com>, Rob Clark <robdclark@gmail.com>,
        "Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>,
        Sean Paul <sean@poorly.run>, "David Airlie" <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Stephen Boyd <swboyd@chromium.org>,
        David Heidelberg <david@ixit.cz>,
        Guo Zhengkui <guozhengkui@vivo.com>,
        Xu Wang <vulab@iscas.ac.cn>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Rob Herring <robh@kernel.org>, <linux-arm-msm@vger.kernel.org>,
        <dri-devel@lists.freedesktop.org>,
        <freedreno@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
References: <20220607110841.53889-1-linmq006@gmail.com>
From:   Abhinav Kumar <quic_abhinavk@quicinc.com>
In-Reply-To: <20220607110841.53889-1-linmq006@gmail.com>
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On 6/7/2022 4:08 AM, Miaoqian Lin wrote:
> of_graph_get_remote_node() returns remote device node pointer with
> refcount incremented, we should use of_node_put() on it
> when not need anymore.
> Add missing of_node_put() to avoid refcount leak.
> 
> Fixes: 86418f90a4c1 ("drm: convert drivers to use of_graph_get_remote_node")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
> ---
>   drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 2 ++
>   1 file changed, 2 insertions(+)
> 

This patch itself looks fine and will cover the cases when there was an 
error and we did not release the refcount.

But, even in the normal cases I am not finding where we are releasing 
the refcount for the panel_node.

I dont see a of_node_put() on mdp4_lcdc_encoder->panel_node.

Am i missing something?

> diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> index fb48c8c19ec3..17cb1fc78379 100644
> --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> @@ -216,6 +216,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>   		encoder = mdp4_lcdc_encoder_init(dev, panel_node);
>   		if (IS_ERR(encoder)) {
>   			DRM_DEV_ERROR(dev->dev, "failed to construct LCDC encoder\n");
> +			of_node_put(panel_node);
>   			return PTR_ERR(encoder);
>   		}
>   
> @@ -225,6 +226,7 @@ static int mdp4_modeset_init_intf(struct mdp4_kms *mdp4_kms,
>   		connector = mdp4_lvds_connector_init(dev, panel_node, encoder);
>   		if (IS_ERR(connector)) {
>   			DRM_DEV_ERROR(dev->dev, "failed to initialize LVDS connector\n");
> +			of_node_put(panel_node);
>   			return PTR_ERR(connector);
>   		}
>