At 2026-01-07 00:49:50, "Sai Krishna Gajula" [off-list ref] wrote:

quoted

-----Original Message-----
From: Slark Xiao <redacted>
Sent: Monday, January 5, 2026 3:50 PM
To: loic.poulain@oss.qualcomm.com; ryazanov.s.a@gmail.com;
johannes@sipsolutions.net; andrew+netdev@lunn.ch;
davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
pabeni@redhat.com; mani@kernel.org
Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org
Subject: [net-next v4 2/8] net: wwan: core: split port creation and
registration

From: Sergey Ryazanov <ryazanov. s. a@ gmail. com> Upcoming GNSS (NMEA)
port type support requires exporting it via the GNSS subsystem. On another
hand, we still need to do basic WWAN core work: find or allocate the WWAN
device, make it the 
From: Sergey Ryazanov <ryazanov.s.a@gmail.com>

Upcoming GNSS (NMEA) port type support requires exporting it via the GNSS
subsystem. On another hand, we still need to do basic WWAN core
work: find or allocate the WWAN device, make it the port parent, etc. To reuse
as much code as possible, split the port creation function into the registration
of a regular WWAN port device, and basic port struct initialization.

To be able to use put_device() uniformly, break the device_register() call into
device_initialize() and device_add() and call device initialization earlier.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---
 drivers/net/wwan/wwan_core.c | 66 ++++++++++++++++++++++--------------
 1 file changed, 40 insertions(+), 26 deletions(-)

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index ade8bbffc93e..edee5ff48f28 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c

@@ -361,7 +361,8 @@ static void wwan_port_destroy(struct device *dev)  {
 	struct wwan_port *port = to_wwan_port(dev);

-	ida_free(&minors, MINOR(port->dev.devt));
+	if (dev->class == &wwan_class)
+		ida_free(&minors, MINOR(dev->devt));
 	mutex_destroy(&port->data_lock);
 	mutex_destroy(&port->ops_lock);
 	kfree(port);

@@ -440,6 +441,41 @@ static int __wwan_port_dev_assign_name(struct

wwan_port *port, const char *fmt)
 	return dev_set_name(&port->dev, "%s", buf);  }

+/* Register a regular WWAN port device (e.g. AT, MBIM, etc.) */ static
+int wwan_port_register_wwan(struct wwan_port *port) {

As per kernel style, braces need to be on next line 
int wwan_port_register_wwan(struct wwan_port *port) 
{
...
}

quoted

+	struct wwan_device *wwandev = to_wwan_dev(port->dev.parent);
+	char namefmt[0x20];
+	int minor, err;
+
+	/* A port is exposed as character device, get a minor */
+	minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1,
GFP_KERNEL);
+	if (minor < 0)
+		return minor;
+
+	port->dev.class = &wwan_class;
+	port->dev.devt = MKDEV(wwan_major, minor);
+
+	/* allocate unique name based on wwan device id, port type and
number */
+	snprintf(namefmt, sizeof(namefmt), "wwan%u%s%%d", wwandev-

quoted

id,

+		 wwan_port_types[port->type].devsuf);
+
+	/* Serialize ports registration */
+	mutex_lock(&wwan_register_lock);
+
+	__wwan_port_dev_assign_name(port, namefmt);
+	err = device_add(&port->dev);
+
+	mutex_unlock(&wwan_register_lock);
+
+	if (err)
+		return err;

Please check, if freeing with ida_free is required before returning err.
if (err) {
   ida_free(&minors, minor);
   return err;
}

Yes, you are right.
And patch 7/8 modifies this file as well. We need to align with that changes
since there are some issues(we still allocates the minor even the cdev is
false). This would lead to the release function can't release the correct
devt.

quoted

+
+	dev_info(&wwandev->dev, "port %s attached\n", dev_name(&port-

quoted

dev));

+
+	return 0;
+}
+
 struct wwan_port *wwan_create_port(struct device *parent,
 				   enum wwan_port_type type,
 				   const struct wwan_port_ops *ops, @@ -
448,8 +484,7 @@ struct wwan_port *wwan_create_port(struct device
*parent,  {
 	struct wwan_device *wwandev;
 	struct wwan_port *port;
-	char namefmt[0x20];
-	int minor, err;
+	int err;

 	if (type > WWAN_PORT_MAX || !ops)
 		return ERR_PTR(-EINVAL);

@@ -461,17 +496,9 @@ struct wwan_port *wwan_create_port(struct device

*parent,
 	if (IS_ERR(wwandev))
 		return ERR_CAST(wwandev);

-	/* A port is exposed as character device, get a minor */
-	minor = ida_alloc_range(&minors, 0, WWAN_MAX_MINORS - 1,
GFP_KERNEL);
-	if (minor < 0) {
-		err = minor;
-		goto error_wwandev_remove;
-	}
-
 	port = kzalloc(sizeof(*port), GFP_KERNEL);
 	if (!port) {
 		err = -ENOMEM;
-		ida_free(&minors, minor);
 		goto error_wwandev_remove;
 	}

@@ -485,27 +512,14 @@ struct wwan_port *wwan_create_port(struct device

*parent,
 	mutex_init(&port->data_lock);

 	port->dev.parent = &wwandev->dev;
-	port->dev.class = &wwan_class;
 	port->dev.type = &wwan_port_dev_type;
-	port->dev.devt = MKDEV(wwan_major, minor);
 	dev_set_drvdata(&port->dev, drvdata);
+	device_initialize(&port->dev);

-	/* allocate unique name based on wwan device id, port type and
number */
-	snprintf(namefmt, sizeof(namefmt), "wwan%u%s%%d", wwandev-

quoted

id,

-		 wwan_port_types[port->type].devsuf);
-
-	/* Serialize ports registration */
-	mutex_lock(&wwan_register_lock);
-
-	__wwan_port_dev_assign_name(port, namefmt);
-	err = device_register(&port->dev);
-
-	mutex_unlock(&wwan_register_lock);
-
+	err = wwan_port_register_wwan(port);
 	if (err)
 		goto error_put_device;

-	dev_info(&wwandev->dev, "port %s attached\n", dev_name(&port-

quoted

dev));

 	return port;

 error_put_device:
--
2.25.1