linux-kernel - Re: [PATCH 08/23] interconnect: qcom: rpm: fix registration race

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Message-ID: <92cbad8e-6e18-4ecf-17a7-3d40a429cad9@linaro.org>
Date:   Fri, 3 Feb 2023 03:53:54 +0100
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Johan Hovold <johan+linaro@...nel.org>,
        Georgi Djakov <djakov@...nel.org>
Cc:     Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Artur Świgoń <a.swigon@...sung.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Jun Nie <jun.nie@...aro.org>,
        Georgi Djakov <georgi.djakov@...aro.org>
Subject: Re: [PATCH 08/23] interconnect: qcom: rpm: fix registration race



On 1.02.2023 11:15, Johan Hovold wrote:
> The current interconnect provider registration interface is inherently
> racy as nodes are not added until the after adding the provider. This
> can specifically cause racing DT lookups to fail.
> 
> Switch to using the new API where the provider is not registered until
> after it has been fully initialised.
> 
> Fixes: 62feb14ee8a3 ("interconnect: qcom: Consolidate interconnect RPM support")
> Fixes: 30c8fa3ec61a ("interconnect: qcom: Add MSM8916 interconnect provider driver")
> Cc: stable@...r.kernel.org	# 5.7
> Cc: Jun Nie <jun.nie@...aro.org>
> Cc: Georgi Djakov <georgi.djakov@...aro.org>
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> ---
Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Konrad
>  drivers/interconnect/qcom/icc-rpm.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
> index da595059cafd..4d0997b210f7 100644
> --- a/drivers/interconnect/qcom/icc-rpm.c
> +++ b/drivers/interconnect/qcom/icc-rpm.c
> @@ -502,7 +502,6 @@ int qnoc_probe(struct platform_device *pdev)
>  	}
>  
>  	provider = &qp->provider;
> -	INIT_LIST_HEAD(&provider->nodes);
>  	provider->dev = dev;
>  	provider->set = qcom_icc_set;
>  	provider->pre_aggregate = qcom_icc_pre_bw_aggregate;
> @@ -510,11 +509,7 @@ int qnoc_probe(struct platform_device *pdev)
>  	provider->xlate_extended = qcom_icc_xlate_extended;
>  	provider->data = data;
>  
> -	ret = icc_provider_add(provider);
> -	if (ret) {
> -		dev_err(dev, "error adding interconnect provider: %d\n", ret);
> -		goto err_disable_clks;
> -	}
> +	icc_provider_init(provider);
>  
>  	for (i = 0; i < num_nodes; i++) {
>  		size_t j;
> @@ -522,7 +517,7 @@ int qnoc_probe(struct platform_device *pdev)
>  		node = icc_node_create(qnodes[i]->id);
>  		if (IS_ERR(node)) {
>  			ret = PTR_ERR(node);
> -			goto err;
> +			goto err_remove_nodes;
>  		}
>  
>  		node->name = qnodes[i]->name;
> @@ -536,19 +531,25 @@ int qnoc_probe(struct platform_device *pdev)
>  	}
>  	data->num_nodes = num_nodes;
>  
> +	ret = icc_provider_register(provider);
> +	if (ret)
> +		goto err_remove_nodes;
> +
>  	platform_set_drvdata(pdev, qp);
>  
>  	/* Populate child NoC devices if any */
>  	if (of_get_child_count(dev->of_node) > 0) {
>  		ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
>  		if (ret)
> -			goto err;
> +			goto err_deregister_provider;
>  	}
>  
>  	return 0;
> -err:
> +
> +err_deregister_provider:
> +	icc_provider_deregister(provider);
> +err_remove_nodes:
>  	icc_nodes_remove(provider);
> -	icc_provider_del(provider);
>  err_disable_clks:
>  	clk_bulk_disable_unprepare(qp->num_clks, qp->bus_clks);
>  
> @@ -560,9 +561,9 @@ int qnoc_remove(struct platform_device *pdev)
>  {
>  	struct qcom_icc_provider *qp = platform_get_drvdata(pdev);
>  
> +	icc_provider_deregister(&qp->provider);
>  	icc_nodes_remove(&qp->provider);
>  	clk_bulk_disable_unprepare(qp->num_clks, qp->bus_clks);
> -	icc_provider_del(&qp->provider);
>  
>  	return 0;
>  }