linux-kernel - [PATCH v2 10/23] interconnect: qcom: rpmh: fix registration race

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Message-Id: <20230306075651.2449-11-johan+linaro@kernel.org>
Date:   Mon,  6 Mar 2023 08:56:38 +0100
From:   Johan Hovold <johan+linaro@...nel.org>
To:     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>,
        "Konrad Dybcio" <konrad.dybcio@...aro.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,
        Johan Hovold <johan+linaro@...nel.org>, stable@...r.kernel.org
Subject: [PATCH v2 10/23] interconnect: qcom: rpmh: fix registration race

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
Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>
Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
---
 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;
 }
-- 
2.39.2