linux-kernel - Re: [PATCH] serial: core: Revert port

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Date:   Wed, 9 Aug 2023 08:26:50 +0300
From:   Tony Lindgren <tony@...mide.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        Dhruva Gole <d-gole@...com>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        John Ogness <john.ogness@...utronix.de>,
        Johan Hovold <johan@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
        Guenter Roeck <groeck7@...il.com>
Subject: Re: [PATCH] serial: core: Revert port_id use

Hi,

* Guenter Roeck <linux@...ck-us.net> [230806 13:19]:
> On Sun, Aug 06, 2023 at 09:20:50AM +0300, Tony Lindgren wrote:
> > Guenter reports boot issues with duplicate sysfs entries for multiport
> > drivers. Let's go back to using port->line for now to fix the regression.
> > 
> > With this change, the serial core port device names are not correct for the
> > hardware specific 8250 single port drivers, but that's a cosmetic issue for
> > now.
> > 
> > Fixes: d962de6ae51f ("serial: core: Fix serial core port id to not use port->line")
> > Reported-by: Guenter Roeck <groeck7@...il.com>
> > Signed-off-by: Tony Lindgren <tony@...mide.com>
> 
> Tested-by: Guenter Roeck <linux@...ck-us.net>

Thanks for testing.

Guenter, care to also test the patch below on top of this fix and
see if things still behave for you?

I'll send a proper patch assuming things test fine.

Regagrds,

Tony

8< --------------------
diff --git a/drivers/tty/serial/serial_base.h b/drivers/tty/serial/serial_base.h
--- a/drivers/tty/serial/serial_base.h
+++ b/drivers/tty/serial/serial_base.h
@@ -16,6 +16,7 @@ struct device;
 
 struct serial_ctrl_device {
 	struct device dev;
+	struct ida ida;
 };
 
 struct serial_port_device {
diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
--- a/drivers/tty/serial/serial_base_bus.c
+++ b/drivers/tty/serial/serial_base_bus.c
@@ -10,6 +10,7 @@
 
 #include <linux/container_of.h>
 #include <linux/device.h>
+#include <linux/idr.h>
 #include <linux/module.h>
 #include <linux/serial_core.h>
 #include <linux/slab.h>
@@ -112,6 +113,8 @@ struct serial_ctrl_device *serial_base_ctrl_add(struct uart_port *port,
 	if (!ctrl_dev)
 		return ERR_PTR(-ENOMEM);
 
+	ida_init(&ctrl_dev->ida);
+
 	err = serial_base_device_init(port, &ctrl_dev->dev,
 				      parent, &serial_ctrl_type,
 				      serial_base_ctrl_release,
@@ -142,16 +145,31 @@ struct serial_port_device *serial_base_port_add(struct uart_port *port,
 						struct serial_ctrl_device *ctrl_dev)
 {
 	struct serial_port_device *port_dev;
+	unsigned int min = 0, max = ~0U;
 	int err;
 
 	port_dev = kzalloc(sizeof(*port_dev), GFP_KERNEL);
 	if (!port_dev)
 		return ERR_PTR(-ENOMEM);
 
+	/* Device driver specified port_id vs automatic assignment? */
+	if (port->port_id) {
+		min = port->port_id;
+		max = port->port_id;
+	}
+
+	err = ida_alloc_range(&ctrl_dev->ida, min, max, GFP_KERNEL);
+	if (err < 0) {
+		kfree(port_dev);
+		return ERR_PTR(err);
+	}
+
+	port->port_id = err;
+
 	err = serial_base_device_init(port, &port_dev->dev,
 				      &ctrl_dev->dev, &serial_port_type,
 				      serial_base_port_release,
-				      port->ctrl_id, port->line);
+				      port->ctrl_id, port->port_id);
 	if (err)
 		goto err_put_device;
 
@@ -165,16 +183,24 @@ struct serial_port_device *serial_base_port_add(struct uart_port *port,
 
 err_put_device:
 	put_device(&port_dev->dev);
+	ida_free(&ctrl_dev->ida, port->port_id);
 
 	return ERR_PTR(err);
 }
 
 void serial_base_port_device_remove(struct serial_port_device *port_dev)
 {
+	struct serial_ctrl_device *ctrl_dev;
+	struct device *parent;
+
 	if (!port_dev)
 		return;
 
+	parent = port_dev->dev.parent;
+	ctrl_dev = to_serial_base_ctrl_device(parent);
+
 	device_del(&port_dev->dev);
+	ida_free(&ctrl_dev->ida, port_dev->port->port_id);
 	put_device(&port_dev->dev);
 }
 
-- 
2.41.0