Re: FAILED: patch "[PATCH] drm/msm: fix OF child-node lookup" failed to apply to 4.14-stable tree

[Johan Hovold <johan@kernel.org>]

On Mon, Nov 19, 2018 at 03:07:37PM +0100, Greg Kroah-Hartman wrote:
> 
> The patch below does not apply to the 4.14-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

This one also depends on

	36156f9241cb ("of: add helper to lookup compatible child node")

Johan

> ------------------ original commit in Linus's tree ------------------
> 
> From f9a7082327e26f54067a49cac2316d31e0cc8ba7 Mon Sep 17 00:00:00 2001
> From: Johan Hovold <johan@kernel.org>
> Date: Mon, 27 Aug 2018 10:21:47 +0200
> Subject: [PATCH] drm/msm: fix OF child-node lookup
> 
> Use the new of_get_compatible_child() helper to lookup the legacy
> pwrlevels child node instead of using of_find_compatible_node(), which
> searches the entire tree from a given start node and thus can return an
> unrelated (i.e.  non-child) node.
> 
> This also addresses a potential use-after-free (e.g. after probe
> deferral) as the tree-wide helper drops a reference to its first
> argument (i.e. the probed device's node).
> 
> While at it, also fix the related child-node reference leak.
> 
> Fixes: e2af8b6b0ca1 ("drm/msm: gpu: Use OPP tables if we can")
> Cc: stable <stable@vger.kernel.org>     # 4.12
> Cc: Jordan Crouse <jcrouse@codeaurora.org>
> Cc: Rob Clark <robdclark@gmail.com>
> Cc: David Airlie <airlied@linux.ie>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> Signed-off-by: Rob Herring <robh@kernel.org>
> 
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index da1363a0c54d..93d70f4a2154 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -633,8 +633,7 @@ static int adreno_get_legacy_pwrlevels(struct device *dev)
>  	struct device_node *child, *node;
>  	int ret;
>  
> -	node = of_find_compatible_node(dev->of_node, NULL,
> -		"qcom,gpu-pwrlevels");
> +	node = of_get_compatible_child(dev->of_node, "qcom,gpu-pwrlevels");
>  	if (!node) {
>  		dev_err(dev, "Could not find the GPU powerlevels\n");
>  		return -ENXIO;
> @@ -655,6 +654,8 @@ static int adreno_get_legacy_pwrlevels(struct device *dev)
>  			dev_pm_opp_add(dev, val, 0);
>  	}
>  
> +	of_node_put(node);
> +
>  	return 0;
>  }
>  
>