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@de.ibm.com>
Cc: Dave Young <hidave.darkstar@gmail.com>
Cc: Gabor Gombas <gombasg@sztaki.hu>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: David Miller <davem@davemloft.net>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 14 insertions, 15 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index d5d542db96fd..f09dde3b1e27 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -552,6 +552,8 @@ static struct kobject *get_device_parent(struct device *dev,
 }
 
 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)
 {
@@ -616,27 +618,27 @@ static struct kobject *get_device_parent(struct device *dev,
         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)
@@ -784,9 +786,7 @@ 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);
@@ -864,6 +864,7 @@ 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;
@@ -1344,15 +1345,12 @@ int device_move(struct device *dev, struct device *new_parent)
 
         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;
         }
@@ -1375,6 +1373,7 @@ int device_move(struct device *dev, struct device *new_parent)
                                 klist_add_tail(&dev->knode_parent,
                                                &old_parent->klist_children);
                 }
+                cleanup_glue_dir(dev, new_parent_kobj);
                 put_device(new_parent);
                 goto out;
         }