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synclink_gt use dynamic tty device registration

PATCH In review Paul Fulghum 2 participants 3 messages May 2, 2007 – May 3, 2007 Char and misc drivers

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#0 lore raw

PATCH 1/1 synclink_gt use dynamic tty device registration

Change synclink_gt driver to use dynamic tty device registration.

drivers/char/synclink_gt.c +18 -16
@@ -3415,6 +3415,9 @@ static void device_init(int adapter_num,
 			}
 		}
 	}
+
+	for (i=0; i < port_count; ++i)
+		tty_register_device(serial_driver, port_array[i]->line, &(port_array[i]->pdev->dev));
 }
 
 static int __devinit init_one(struct pci_dev *dev,
@@ -3466,6 +3469,8 @@ static void slgt_cleanup(void)
 	printk("unload %s %s\n", driver_name, driver_version);
 
 	if (serial_driver) {
+		for (info=slgt_device_list ; info != NULL ; info=info->next_device)
+			tty_unregister_device(serial_driver, info->line);
 		if ((rc = tty_unregister_driver(serial_driver)))
 			DBGERR(("tty_unregister_driver error=%d\n", rc));
 		put_tty_driver(serial_driver);
@@ -3506,23 +3511,10 @@ static int __init slgt_init(void)
 
  	printk("%s %s\n", driver_name, driver_version);
 
-	slgt_device_count = 0;
-	if ((rc = pci_register_driver(&pci_driver)) < 0) {
-		printk("%s pci_register_driver error=%d\n", driver_name, rc);
-		return rc;
-	}
-	pci_registered = 1;
-
-	if (!slgt_device_list) {
-		printk("%s no devices found\n",driver_name);
-		pci_unregister_driver(&pci_driver);
-		return -ENODEV;
-	}
-
 	serial_driver = alloc_tty_driver(MAX_DEVICES);
 	if (!serial_driver) {
-		rc = -ENOMEM;
-		goto error;
+		printk("%s can't allocate tty driver\n", driver_name);
+		return -ENOMEM;
 	}
 
 	/* Initialize the tty_driver structure */
@@ -3539,7 +3531,7 @@ static int __init slgt_init(void)
 		B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 	serial_driver->init_termios.c_ispeed = 9600;
 	serial_driver->init_termios.c_ospeed = 9600;
-	serial_driver->flags = TTY_DRIVER_REAL_RAW;
+	serial_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 	tty_set_operations(serial_driver, &ops);
 	if ((rc = tty_register_driver(serial_driver)) < 0) {
 		DBGERR(("%s can't register serial driver\n", driver_name));
@@ -3552,6 +3544,16 @@ static int __init slgt_init(void)
 		driver_name, driver_version,
 		serial_driver->major);
 
+	slgt_device_count = 0;
+	if ((rc = pci_register_driver(&pci_driver)) < 0) {
+		printk("%s pci_register_driver error=%d\n", driver_name, rc);
+		goto error;
+	}
+	pci_registered = 1;
+
+	if (!slgt_device_list)
+		printk("%s no devices found\n",driver_name);
+
 	return 0;
 
 error:
#1 lore raw

Review

Quoted 11 lines · On Wed, 02 May 2007 11:17:33 -0500 Paul Fulghum <[email protected]> wrote:

Change synclink_gt driver to use dynamic tty device registration.

...

(quoted diff) +5 -0
+	for (i=0; i < port_count; ++i)
+		tty_register_device(serial_driver, port_array[i]->line, &(port_array[i]->pdev->dev));
...
+		for (info=slgt_device_list ; info != NULL ; info=info->next_device)
+			tty_unregister_device(serial_driver, info->line);
...
+	if ((rc = pci_register_driver(&pci_driver)) < 0) {

hm, not a big fan of kernel coding style, I see.

What's going to happen here if tty_register_device() fails?

#2 lore raw
Quoted 6 lines · Andrew Morton
Quoted 4 lines · On Wed, 02 May 2007 11:17:33 -0500 Paul Fulghum <[email protected]> wrote:

Change synclink_gt driver to use dynamic tty device registration.

...

Quoted 9 lines

Review

Quoted 7 lines
(quoted diff) +5 -0
+	for (i=0; i < port_count; ++i)
+		tty_register_device(serial_driver, port_array[i]->line, &(port_array[i]->pdev->dev));
...
+		for (info=slgt_device_list ; info != NULL ; info=info->next_device)
+			tty_unregister_device(serial_driver, info->line);
...
+	if ((rc = pci_register_driver(&pci_driver)) < 0) {

hm, not a big fan of kernel coding style, I see.

It varies. If this idiom bothers you, I can split it into 2 lines.

Quoted 1 line

What's going to happen here if tty_register_device() fails?

Then the device will not be accessible as a tty device. It may still be accessible as a network device.
On driver unload, tty_unregister_device() does nothing because the device was never created.

In this case, tracking the return value does not change anything. I could add a printk on error to better inform the user that the kernel's plumbing went south.

Signature · 2 lines
Paul Fulghum
Microgate Systems, Ltd