linux-kernel - Re: [PATCH 10/23] interconnect: qcom: rpmh: fix registration race

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Message-ID: <26f87cbe-58f8-e74a-3dd3-2f27cb092791@linaro.org>
Date:   Fri, 3 Feb 2023 03:55:21 +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
Subject: Re: [PATCH 10/23] interconnect: qcom: rpmh: 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: 976daac4a1c5 ("interconnect: qcom: Consolidate interconnect RPMh support")
> Cc: stable@...r.kernel.org      # 5.7
> Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> ---
Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Konrad
>  drivers/interconnect/qcom/icc-rpmh.c | 25 +++++++++++++++----------
>  1 file changed, 15 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/interconnect/qcom/icc-rpmh.c b/drivers/interconnect/qcom/icc-rpmh.c
> index 5168bbf3d92f..fdb5e58e408b 100644
> --- a/drivers/interconnect/qcom/icc-rpmh.c
> +++ b/drivers/interconnect/qcom/icc-rpmh.c
> @@ -192,9 +192,10 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev)
>  	provider->pre_aggregate = qcom_icc_pre_aggregate;
>  	provider->aggregate = qcom_icc_aggregate;
>  	provider->xlate_extended = qcom_icc_xlate_extended;
> -	INIT_LIST_HEAD(&provider->nodes);
>  	provider->data = data;
>  
> +	icc_provider_init(provider);
> +
>  	qp->dev = dev;
>  	qp->bcms = desc->bcms;
>  	qp->num_bcms = desc->num_bcms;
> @@ -203,10 +204,6 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev)
>  	if (IS_ERR(qp->voter))
>  		return PTR_ERR(qp->voter);
>  
> -	ret = icc_provider_add(provider);
> -	if (ret)
> -		return ret;
> -
>  	for (i = 0; i < qp->num_bcms; i++)
>  		qcom_icc_bcm_init(qp->bcms[i], dev);
>  
> @@ -218,7 +215,7 @@ int qcom_icc_rpmh_probe(struct platform_device *pdev)
>  		node = icc_node_create(qn->id);
>  		if (IS_ERR(node)) {
>  			ret = PTR_ERR(node);
> -			goto err;
> +			goto err_remove_nodes;
>  		}
>  
>  		node->name = qn->name;
> @@ -232,19 +229,27 @@ int qcom_icc_rpmh_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);
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(qcom_icc_rpmh_probe);
> @@ -253,8 +258,8 @@ int qcom_icc_rpmh_remove(struct platform_device *pdev)
>  {
>  	struct qcom_icc_provider *qp = platform_get_drvdata(pdev);
>  
> +	icc_provider_deregister(&qp->provider);
>  	icc_nodes_remove(&qp->provider);
> -	icc_provider_del(&qp->provider);
>  
>  	return 0;
>  }