linux-kernel - [PATCH 1/4] regulator: qcom_spmi: Fix warning Bad of_node

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Date:   Mon, 16 Jul 2018 13:35:22 +0200
From:   Niklas Cassel <niklas.cassel@...aro.org>
To:     broonie@...nel.org, Liam Girdwood <lgirdwood@...il.com>
Cc:     linux-arm-msm@...r.kernel.org,
        Niklas Cassel <niklas.cassel@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] regulator: qcom_spmi: Fix warning Bad of_node_put()

For of_find_node_by_name(), you typically pass what the previous call
returned. Therefore, of_find_node_by_name() increases the refcount of
the returned node, and decreases the refcount of the node passed as the
first argument.

However, in this case we don't pass what the previous call returned,
so we have to increase the refcount of the first argument to compensate.

Also add a missing of_node_put() for the returned value, since this was
previously being leaked.

OF: ERROR: Bad of_node_put() on /soc/qcom,spmi@...f000/pmic@...egulators
CPU: 1 PID: 1 Comm: swapper/0 Tainted: G        W         4.18.0-rc4-00223-gefd7b360b70e #12
Hardware name: Qualcomm Technologies, Inc. DB820c (DT)
Call trace:
 dump_backtrace+0x0/0x1a8
 show_stack+0x14/0x20
 dump_stack+0x90/0xb4
 of_node_release+0x74/0x78
 kobject_put+0x90/0x1f0
 of_node_put+0x14/0x20
 of_find_node_by_name+0x80/0xd8
 qcom_spmi_regulator_probe+0x30c/0x508

Fixes: 0caecaa87202 ("regulator: qcom_spmi: Add support for SAW")
Signed-off-by: Niklas Cassel <niklas.cassel@...aro.org>
---
 drivers/regulator/qcom_spmi-regulator.c | 42 ++++++++++++++++++-------
 1 file changed, 30 insertions(+), 12 deletions(-)

diff --git a/drivers/regulator/qcom_spmi-regulator.c b/drivers/regulator/qcom_spmi-regulator.c
index 9817f1a75342..8b921b1b1df5 100644
--- a/drivers/regulator/qcom_spmi-regulator.c
+++ b/drivers/regulator/qcom_spmi-regulator.c
@@ -1752,7 +1752,8 @@ static int qcom_spmi_regulator_probe(struct platform_device *pdev)
 	const char *name;
 	struct device *dev = &pdev->dev;
 	struct device_node *node = pdev->dev.of_node;
-	struct device_node *syscon;
+	struct device_node *syscon, *reg_node;
+	struct property *reg_prop;
 	int ret, lenp;
 	struct list_head *vreg_list;
 
@@ -1780,10 +1781,18 @@ static int qcom_spmi_regulator_probe(struct platform_device *pdev)
 
 	for (reg = match->data; reg->name; reg++) {
 
-		if (saw_regmap && \
-		    of_find_property(of_find_node_by_name(node, reg->name), \
-				     "qcom,saw-slave", &lenp)) {
-			continue;
+		if (saw_regmap) {
+			/*
+			 * Compensate for of_node_put() in
+			 * of_find_node_by_name()
+			 */
+			of_node_get(node);
+			reg_node = of_find_node_by_name(node, reg->name);
+			reg_prop = of_find_property(reg_node, "qcom,saw-slave",
+						    &lenp);
+			of_node_put(reg_node);
+			if (reg_prop)
+				continue;
 		}
 
 		vreg = devm_kzalloc(dev, sizeof(*vreg), GFP_KERNEL);
@@ -1816,13 +1825,22 @@ static int qcom_spmi_regulator_probe(struct platform_device *pdev)
 		if (ret)
 			continue;
 
-		if (saw_regmap && \
-		    of_find_property(of_find_node_by_name(node, reg->name), \
-				     "qcom,saw-leader", &lenp)) {
-			spmi_saw_ops = *(vreg->desc.ops);
-			spmi_saw_ops.set_voltage_sel = \
-				spmi_regulator_saw_set_voltage;
-			vreg->desc.ops = &spmi_saw_ops;
+		if (saw_regmap) {
+			/*
+			 * Compensate for of_node_put() in
+			 * of_find_node_by_name()
+			 */
+			of_node_get(node);
+			reg_node = of_find_node_by_name(node, reg->name);
+			reg_prop = of_find_property(reg_node, "qcom,saw-leader",
+						    &lenp);
+			of_node_put(reg_node);
+			if (reg_prop) {
+				spmi_saw_ops = *(vreg->desc.ops);
+				spmi_saw_ops.set_voltage_sel =
+					spmi_regulator_saw_set_voltage;
+				vreg->desc.ops = &spmi_saw_ops;
+			}
 		}
 
 		config.dev = dev;
-- 
2.17.1