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

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Message-Id: <20230201101559.15529-9-johan+linaro@kernel.org>
Date:   Wed,  1 Feb 2023 11:15:44 +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,
        Jun Nie <jun.nie@...aro.org>,
        Georgi Djakov <georgi.djakov@...aro.org>
Subject: [PATCH 08/23] interconnect: qcom: rpm: 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: 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>
---
 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;
 }
-- 
2.39.1