linux-kernel - [PATCH v2 3/6] leds: bd2606mvv: fix device child node usage in bd2606mvv

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Message-Id: <20240721-device_for_each_child_node-available-v2-3-f33748fd8b2d@gmail.com>
Date: Sun, 21 Jul 2024 17:19:03 +0200
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, 
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
 Jonathan Cameron <jic23@...nel.org>, Rob Herring <robh@...nel.org>, 
 Daniel Scally <djrscally@...il.com>, 
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
 Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Jean Delvare <jdelvare@...e.com>, Guenter Roeck <linux@...ck-us.net>, 
 Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>, 
 Marcin Wojtas <marcin.s.wojtas@...il.com>, 
 Russell King <linux@...linux.org.uk>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Andreas Kemnade <andreas@...nade.info>
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-hwmon@...r.kernel.org, linux-leds@...r.kernel.org, 
 netdev@...r.kernel.org, Javier Carrasco <javier.carrasco.cruz@...il.com>
Subject: [PATCH v2 3/6] leds: bd2606mvv: fix device child node usage in
 bd2606mvv_probe()

The current implementation accesses the `child` fwnode handle outside of
fwnode_for_each_available_child_node() without incrementing its
refcount. Add the missing call to `fwnode_handle_get(child)`.

The cleanup process where `child` is accessed is not right either
because a single call to `fwnode_handle_put()` is carried out in case of
an error, ignoring unasigned nodes at the point when the error happens.
Keep `child` inside of the first loop, and use the helper pointer that
receives references via `fwnode_handle_get()` to handle the child nodes
within the second loop.

Moreover, the iterated nodes are direct children of the device node,
and the `device_for_each_child_node()` macro accounts for child node
availability. By restricting `child` to live within that loop, the
scoped version of it can be used to simplify the error handling.

`fwnode_for_each_available_child_node()` is meant to access the child
nodes of an fwnode, and therefore not direct child nodes of the device
node.

Use `device_for_each_child_node_scoped()` to indicate device's direct
child nodes.

Fixes: 8325642d2757 ("leds: bd2606mvv: Driver for the Rohm 6 Channel i2c LED driver")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@...il.com>
---
 drivers/leds/leds-bd2606mvv.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/drivers/leds/leds-bd2606mvv.c b/drivers/leds/leds-bd2606mvv.c
index 3fda712d2f80..c1181a35d0f7 100644
--- a/drivers/leds/leds-bd2606mvv.c
+++ b/drivers/leds/leds-bd2606mvv.c
@@ -69,16 +69,14 @@ static const struct regmap_config bd2606mvv_regmap = {

 static int bd2606mvv_probe(struct i2c_client *client)
 {
-	struct fwnode_handle *np, *child;
 	struct device *dev = &client->dev;
 	struct bd2606mvv_priv *priv;
 	struct fwnode_handle *led_fwnodes[BD2606_MAX_LEDS] = { 0 };
 	int active_pairs[BD2606_MAX_LEDS / 2] = { 0 };
 	int err, reg;
-	int i;
+	int i, j;

-	np = dev_fwnode(dev);
-	if (!np)
+	if (!dev_fwnode(dev))
 		return -ENODEV;

 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
@@ -94,20 +92,18 @@ static int bd2606mvv_probe(struct i2c_client *client)

 	i2c_set_clientdata(client, priv);

-	fwnode_for_each_available_child_node(np, child) {
+	device_for_each_child_node_scoped(dev, child) {
 		struct bd2606mvv_led *led;

 		err = fwnode_property_read_u32(child, "reg", &reg);
-		if (err) {
-			fwnode_handle_put(child);
+		if (err)
 			return err;
-		}
-		if (reg < 0 || reg >= BD2606_MAX_LEDS || led_fwnodes[reg]) {
-			fwnode_handle_put(child);
+
+		if (reg < 0 || reg >= BD2606_MAX_LEDS || led_fwnodes[reg])
 			return -EINVAL;
-		}
+
 		led = &priv->leds[reg];
-		led_fwnodes[reg] = child;
+		led_fwnodes[reg] = fwnode_handle_get(child);
 		active_pairs[reg / 2]++;
 		led->priv = priv;
 		led->led_no = reg;
@@ -130,7 +126,8 @@ static int bd2606mvv_probe(struct i2c_client *client)
 						     &priv->leds[i].ldev,
 						     &init_data);
 		if (err < 0) {
-			fwnode_handle_put(child);
+			for (j = i; j < BD2606_MAX_LEDS; j++)
+				fwnode_handle_put(led_fwnodes[j]);
 			return dev_err_probe(dev, err,
 					     "couldn't register LED %s\n",
 					     priv->leds[i].ldev.name);

-- 
2.43.0