linux-kernel - [PATCH 1/5] uio: Simplify the lifetime logic of struct uio

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Date:	Sun, 26 Sep 2010 15:46:56 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Greg KH <greg@...ah.com>
Cc:	Greg KH <gregkh@...e.de>, "Hans J. Koch" <hjk@...utronix.de>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 1/5] uio: Simplify the lifetime logic of struct uio_device.


Embed struct device into struct uio_device, and use
the refcounting and the release method of struct device
to control struct uio_device.

This allows device_create and device_destroy to be replaced
with the more standard device_register and device_unregister,
and allows the struct device reference count to act as a
reference count on struct idev as well.

Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
---
 drivers/uio/uio.c |   42 ++++++++++++++++++++++++++++--------------
 1 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 6285afb..565559c 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -30,7 +30,7 @@
 
 struct uio_device {
 	struct module		*owner;
-	struct device		*dev;
+	struct device		device;
 	int			minor;
 	atomic_t		event;
 	struct fasync_struct	*async_queue;
@@ -279,7 +279,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
 		if (!map_found) {
 			map_found = 1;
 			idev->map_dir = kobject_create_and_add("maps",
-							&idev->dev->kobj);
+							&idev->device.kobj);
 			if (!idev->map_dir)
 				goto err_map;
 		}
@@ -304,7 +304,7 @@ static int uio_dev_add_attributes(struct uio_device *idev)
 		if (!portio_found) {
 			portio_found = 1;
 			idev->portio_dir = kobject_create_and_add("portio",
-							&idev->dev->kobj);
+							&idev->device.kobj);
 			if (!idev->portio_dir)
 				goto err_portio;
 		}
@@ -339,7 +339,7 @@ err_map:
 		kobject_put(&map->kobj);
 	}
 	kobject_put(idev->map_dir);
-	dev_err(idev->dev, "error creating sysfs files (%d)\n", ret);
+	dev_err(&idev->device, "error creating sysfs files (%d)\n", ret);
 	return ret;
 }
 
@@ -789,6 +789,13 @@ static void release_uio_class(void)
 	uio_major_cleanup();
 }
 
+static void uio_device_release(struct device *dev)
+{
+	struct uio_device *idev = dev_get_drvdata(dev);
+
+	kfree(idev);
+}
+
 /**
  * uio_register_device - register a new userspace IO device
  * @owner:	module that creates the new device
@@ -824,14 +831,19 @@ int __uio_register_device(struct module *owner,
 	if (ret)
 		goto err_get_minor;
 
-	idev->dev = device_create(&uio_class, parent,
-				  MKDEV(uio_major, idev->minor), idev,
-				  "uio%d", idev->minor);
-	if (IS_ERR(idev->dev)) {
-		printk(KERN_ERR "UIO: device register failed\n");
-		ret = PTR_ERR(idev->dev);
+	idev->device.devt = MKDEV(uio_major, idev->minor);
+	idev->device.class = &uio_class;
+	idev->device.parent = parent;
+	idev->device.release = uio_device_release;
+	dev_set_drvdata(&idev->device, idev);
+
+	ret = kobject_set_name(&idev->device.kobj, "uio%d", idev->minor);
+	if (ret)
+		goto err_device_create;
+
+	ret = device_register(&idev->device);
+	if (ret)
 		goto err_device_create;
-	}
 
 	ret = uio_dev_add_attributes(idev);
 	if (ret)
@@ -851,7 +863,10 @@ int __uio_register_device(struct module *owner,
 err_request_irq:
 	uio_dev_del_attributes(idev);
 err_uio_dev_add_attributes:
-	device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
+	uio_free_minor(idev);
+	device_unregister(&idev->device);
+	return ret;
+
 err_device_create:
 	uio_free_minor(idev);
 err_get_minor:
@@ -882,8 +897,7 @@ void uio_unregister_device(struct uio_info *info)
 
 	uio_dev_del_attributes(idev);
 
-	device_destroy(&uio_class, MKDEV(uio_major, idev->minor));
-	kfree(idev);
+	device_unregister(&idev->device);
 
 	return;
 }
-- 
1.7.2.2

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