linux-kernel - [Patch] Driver core: Cleanup get_device_parent() in device_add() and device

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Message-ID: <20080121160944.1170bc12@gondolin.boeblingen.de.ibm.com>
Date:	Mon, 21 Jan 2008 16:09:44 +0100
From:	Cornelia Huck <cornelia.huck@...ibm.com>
To:	"Greg KH" <greg@...ah.com>
Cc:	"Dave Young" <hidave.darkstar@...il.com>,
	"Gabor Gombas" <gombasg@...aki.hu>, "Tejun Heo" <htejun@...il.com>,
	"Al Viro" <viro@...iv.linux.org.uk>, linux-kernel@...r.kernel.org,
	bluez-devel@...ts.sf.net, kay.sievers@...y.org,
	"Marcel Holtmann" <marcel@...tmann.org>, davem@...emloft.net
Subject: [Patch] Driver core: Cleanup get_device_parent() in device_add()
 and device_move().

Make setup_parent() void as get_device_parent() will always return
either a valid kobject or NULL.
Introduce cleanup_glue_dir() to drop reference grabbed on "glue"
directory by get_device_parent(). Use it for cleanup in device_move()
and device_add() on errors.

This should fix the refcounting problem reported in
http://marc.info/?l=linux-kernel&m=120052487909200&w=2

Signed-off-by: Cornelia Huck <cornelia.huck@...ibm.com>

---
 drivers/base/core.c |   29 ++++++++++++++---------------
 1 files changed, 14 insertions(+), 15 deletions(-)

--- linux-2.6.orig/drivers/base/core.c
+++ linux-2.6/drivers/base/core.c
@@ -553,6 +553,8 @@ static struct kobject *get_device_parent
 }
 
 static inline void cleanup_device_parent(struct device *dev) {}
+static inline void cleanup_glue_dir(struct device *dev,
+				    struct kobject *glue_dir) {}
 #else
 static struct kobject *virtual_device_parent(struct device *dev)
 {
@@ -617,27 +619,27 @@ static struct kobject *get_device_parent
 	return NULL;
 }
 
-static void cleanup_device_parent(struct device *dev)
+static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
 {
-	struct kobject *glue_dir = dev->kobj.parent;
-
 	/* see if we live in a "glue" directory */
 	if (!dev->class || glue_dir->kset != &dev->class->class_dirs)
 		return;
 
 	kobject_put(glue_dir);
 }
+
+static void cleanup_device_parent(struct device *dev)
+{
+	cleanup_glue_dir(dev, dev->kobj.parent);
+}
 #endif
 
-static int setup_parent(struct device *dev, struct device *parent)
+static void setup_parent(struct device *dev, struct device *parent)
 {
 	struct kobject *kobj;
 	kobj = get_device_parent(dev, parent);
-	if (IS_ERR(kobj))
-		return PTR_ERR(kobj);
 	if (kobj)
 		dev->kobj.parent = kobj;
-	return 0;
 }
 
 static int device_add_class_symlinks(struct device *dev)
@@ -785,9 +787,7 @@ int device_add(struct device *dev)
 	pr_debug("device: '%s': %s\n", dev->bus_id, __FUNCTION__);
 
 	parent = get_device(dev->parent);
-	error = setup_parent(dev, parent);
-	if (error)
-		goto Error;
+	setup_parent(dev, parent);
 
 	/* first, register with generic layer. */
 	error = kobject_add(&dev->kobj, dev->kobj.parent, "%s", dev->bus_id);
@@ -865,6 +865,7 @@ int device_add(struct device *dev)
 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
 	kobject_del(&dev->kobj);
  Error:
+	cleanup_device_parent(dev);
 	if (parent)
 		put_device(parent);
 	goto Done;
@@ -1345,15 +1346,12 @@ int device_move(struct device *dev, stru
 
 	new_parent = get_device(new_parent);
 	new_parent_kobj = get_device_parent (dev, new_parent);
-	if (IS_ERR(new_parent_kobj)) {
-		error = PTR_ERR(new_parent_kobj);
-		put_device(new_parent);
-		goto out;
-	}
+
 	pr_debug("device: '%s': %s: moving to '%s'\n", dev->bus_id,
 		 __FUNCTION__, new_parent ? new_parent->bus_id : "<NULL>");
 	error = kobject_move(&dev->kobj, new_parent_kobj);
 	if (error) {
+		cleanup_glue_dir(dev, new_parent_kobj);
 		put_device(new_parent);
 		goto out;
 	}
@@ -1376,6 +1374,7 @@ int device_move(struct device *dev, stru
 				klist_add_tail(&dev->knode_parent,
 					       &old_parent->klist_children);
 		}
+		cleanup_glue_dir(dev, new_parent_kobj);
 		put_device(new_parent);
 		goto out;
 	}
--
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