From af12a9e4d223b9a7783edd370e8b2f7c198a22bd Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@mev.co.uk>
Date: Wed, 24 Mar 2010 11:53:09 +0000
Subject: [PATCH] The 'open' method in struct comedi_device_struct now returns
 0 on success and a negative errno on failure.  The 'open' method must clean
 up after itself on failure as the 'close' method won't be called.  A failure
 causes the 'open' file operation for the comedi device to fail.

The dt9812 and serial2002 drivers now make use of the ability to return
an error.
---
 comedi/comedi_fops.c        | 9 ++++++++-
 comedi/drivers/dt9812.c     | 6 +++++-
 comedi/drivers/jr3_pci.c    | 3 ++-
 comedi/drivers/serial2002.c | 9 ++++++---
 include/linux/comedidev.h   | 2 +-
 5 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/comedi/comedi_fops.c b/comedi/comedi_fops.c
index 19295728..9a5e0ea2 100644
--- a/comedi/comedi_fops.c
+++ b/comedi/comedi_fops.c
@@ -1837,7 +1837,14 @@ ok:
 	}
 
 	if (dev->attached && dev->use_count == 0 && dev->open) {
-		dev->open(dev);
+		int rc = dev->open(dev);
+
+		if (rc < 0) {
+			module_put(dev->driver->module);
+			module_put(THIS_MODULE);
+			mutex_unlock(&dev->mutex);
+			return rc;
+		}
 	}
 
 	dev->use_count++;
diff --git a/comedi/drivers/dt9812.c b/comedi/drivers/dt9812.c
index 8afb9cb9..7d69a161 100644
--- a/comedi/drivers/dt9812.c
+++ b/comedi/drivers/dt9812.c
@@ -685,8 +685,10 @@ static struct usb_driver dt9812_usb_driver = {
  * Comedi functions
  */
 
-static void dt9812_comedi_open(comedi_device * dev)
+static int dt9812_comedi_open(comedi_device * dev)
 {
+	int result = -ENODEV;
+
 	down(&devpriv->slot->mutex);
 	if (devpriv->slot->usb) {
 		// We have an attached device, fill in current range info
@@ -729,8 +731,10 @@ static void dt9812_comedi_open(comedi_device * dev)
 			}
 			break;
 		}
+		result = 0;
 	}
 	up(&devpriv->slot->mutex);
+	return result;
 }
 
 static int dt9812_di_rinsn(comedi_device * dev, comedi_subdevice * s,
diff --git a/comedi/drivers/jr3_pci.c b/comedi/drivers/jr3_pci.c
index 0482a3fb..220e585c 100644
--- a/comedi/drivers/jr3_pci.c
+++ b/comedi/drivers/jr3_pci.c
@@ -372,7 +372,7 @@ static int jr3_pci_ai_insn_read(comedi_device * dev, comedi_subdevice * s,
 	return result;
 }
 
-static void jr3_pci_open(comedi_device * dev)
+static int jr3_pci_open(comedi_device * dev)
 {
 	int i;
 	jr3_pci_dev_private *devpriv = dev->private;
@@ -387,6 +387,7 @@ static void jr3_pci_open(comedi_device * dev)
 				p->channel_no);
 		}
 	}
+	return 0;
 }
 
 int read_idm_word(const u8 * data, size_t size, int *pos, unsigned int *val)
diff --git a/comedi/drivers/serial2002.c b/comedi/drivers/serial2002.c
index b0e285e8..974f0a1c 100644
--- a/comedi/drivers/serial2002.c
+++ b/comedi/drivers/serial2002.c
@@ -390,15 +390,16 @@ static void serial_write(struct file *f, struct serial_data data)
 	}
 }
 
-static void serial_2002_open(comedi_device * dev)
+static int serial_2002_open(comedi_device * dev)
 {
+	int result;
 	char port[20];
 
 	sprintf(port, "/dev/ttyS%d", devpriv->port);
 	devpriv->tty = filp_open(port, 0, O_RDWR);
 	if (IS_ERR(devpriv->tty)) {
-		printk("serial_2002: file open error = %ld\n",
-			PTR_ERR(devpriv->tty));
+		result = (int)PTR_ERR(devpriv->tty);
+		printk("serial_2002: file open error = %d\n", result);
 	} else {
 		typedef struct {
 			short int kind;
@@ -651,7 +652,9 @@ static void serial_2002_open(comedi_device * dev)
 				}
 			}
 		}
+		result = 0;
 	}
+	return result;
 }
 
 static void serial_2002_close(comedi_device * dev)
diff --git a/include/linux/comedidev.h b/include/linux/comedidev.h
index b8db1380..6672d6e3 100644
--- a/include/linux/comedidev.h
+++ b/include/linux/comedidev.h
@@ -286,7 +286,7 @@ struct comedi_device_struct {
 
 	struct fasync_struct *async_queue;
 
-	void (*open) (comedi_device * dev);
+	int (*open) (comedi_device * dev);
 	void (*close) (comedi_device * dev);
 };
 
-- 
2.26.2