linux-kernel - [PATCH 2/2] regulator: hi655x: Bump parent pmic module use count

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Message-Id: <20170321045341.4833-3-lintonrjeremy@gmail.com>
Date:   Mon, 20 Mar 2017 23:53:41 -0500
From:   Jeremy Linton <lintonrjeremy@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     broonie@...nel.org, lgirdwood@...il.com, puck.chen@...ilicon.com,
        lee.jones@...aro.org, Jeremy Linton <lintonrjeremy@...il.com>
Subject: [PATCH 2/2] regulator: hi655x: Bump parent pmic module use count

The hi655x-regulator driver depends on the parent pmic/mfc
device driver but doesn't increase its use count. This results
in system crashes if the parent module is unloaded while the
regulators are still in use. Add explicit module get/put
calls to keep the parent from being unloaded.

Signed-off-by: Jeremy Linton <lintonrjeremy@...il.com>
---
 drivers/regulator/hi655x-regulator.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/hi655x-regulator.c b/drivers/regulator/hi655x-regulator.c
index aca1846..5a461d4 100644
--- a/drivers/regulator/hi655x-regulator.c
+++ b/drivers/regulator/hi655x-regulator.c
@@ -185,16 +185,29 @@ static int hi655x_regulator_probe(struct platform_device *pdev)
 	struct hi655x_pmic *pmic;
 	struct regulator_config config = { };
 	struct regulator_dev *rdev;
+	struct device *parent = pdev->dev.parent;
 
-	pmic = dev_get_drvdata(pdev->dev.parent);
+	if (!parent) {
+		dev_err(&pdev->dev, "no regulator parent node\n");
+		return -ENODEV;
+	}
+
+	pmic = dev_get_drvdata(parent);
 	if (!pmic) {
 		dev_err(&pdev->dev, "no pmic in the regulator parent node\n");
 		return -ENODEV;
 	}
 
+	if (!try_module_get(parent->driver->owner)) {
+		dev_err(&pdev->dev, "unable to get parent module\n");
+		return -ENODEV;
+	}
+
 	regulator = devm_kzalloc(&pdev->dev, sizeof(*regulator), GFP_KERNEL);
-	if (!regulator)
+	if (!regulator)	{
+		module_put(parent->driver->owner);
 		return -ENOMEM;
+	}
 
 	platform_set_drvdata(pdev, regulator);
 
@@ -214,11 +227,20 @@ static int hi655x_regulator_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int hi655x_regulator_remove(struct platform_device *pdev)
+{
+	struct device *parent = pdev->dev.parent;
+
+	module_put(parent->driver->owner);
+	return 0;
+}
+
 static struct platform_driver hi655x_regulator_driver = {
 	.driver = {
 		.name	= "hi655x-regulator",
 	},
 	.probe	= hi655x_regulator_probe,
+	.remove = hi655x_regulator_remove
 };
 module_platform_driver(hi655x_regulator_driver);
 
-- 
2.10.2