driver core: Introduce device_move(): move a device to a new parent.

Provide a function device_move() to move a device to a new parent device. Add
auxilliary functions kobject_move() and sysfs_move_dir().
kobject_move() generates a new uevent of type KOBJ_MOVE, containing the
previous path (DEVPATH_OLD) in addition to the usual values. For this, a new
interface kobject_uevent_env() is created that allows to add further
environmental data to the uevent at the kobject layer.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

lib/kobject.c

@@ -310,6 +310,56 @@ int kobject_rename(struct kobject * kobj, const char *new_name)
 	return error;
 }
 
+/**
+ *	kobject_move - move object to another parent
+ *	@kobj:	object in question.
+ *	@new_parent: object's new parent
+ */
+
+int kobject_move(struct kobject *kobj, struct kobject *new_parent)
+{
+	int error;
+	struct kobject *old_parent;
+	const char *devpath = NULL;
+	char *devpath_string = NULL;
+	char *envp[2];
+
+	kobj = kobject_get(kobj);
+	if (!kobj)
+		return -EINVAL;
+	new_parent = kobject_get(new_parent);
+	if (!new_parent) {
+		error = -EINVAL;
+		goto out;
+	}
+	/* old object path */
+	devpath = kobject_get_path(kobj, GFP_KERNEL);
+	if (!devpath) {
+		error = -ENOMEM;
+		goto out;
+	}
+	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
+	if (!devpath_string) {
+		error = -ENOMEM;
+		goto out;
+	}
+	sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
+	envp[0] = devpath_string;
+	envp[1] = NULL;
+	error = sysfs_move_dir(kobj, new_parent);
+	if (error)
+		goto out;
+	old_parent = kobj->parent;
+	kobj->parent = new_parent;
+	kobject_put(old_parent);
+	kobject_uevent_env(kobj, KOBJ_MOVE, envp);
+out:
+	kobject_put(kobj);
+	kfree(devpath_string);
+	kfree(devpath);
+	return error;
+}
+
 /**
  *	kobject_del - unlink kobject from hierarchy.
  * 	@kobj:	object.

lib/kobject_uevent.c

@@ -50,18 +50,22 @@ static char *action_to_string(enum kobject_action action)
 		return "offline";
 	case KOBJ_ONLINE:
 		return "online";
+	case KOBJ_MOVE:
+		return "move";
 	default:
 		return NULL;
 	}
 }
 
 /**
- * kobject_uevent - notify userspace by ending an uevent
+ * kobject_uevent_env - send an uevent with environmental data
  *
- * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
+ * @action: action that is happening (usually KOBJ_MOVE)
  * @kobj: struct kobject that the action is happening to
+ * @envp_ext: pointer to environmental data
  */
-void kobject_uevent(struct kobject *kobj, enum kobject_action action)
+void kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
+			char *envp_ext[])
 {
 	char **envp;
 	char *buffer;
@@ -76,6 +80,7 @@ void kobject_uevent(struct kobject *kobj, enum kobject_action action)
 	char *seq_buff;
 	int i = 0;
 	int retval;
+	int j;
 
 	pr_debug("%s\n", __FUNCTION__);
 
@@ -134,7 +139,8 @@ void kobject_uevent(struct kobject *kobj, enum kobject_action action)
 	scratch += sprintf (scratch, "DEVPATH=%s", devpath) + 1;
 	envp [i++] = scratch;
 	scratch += sprintf(scratch, "SUBSYSTEM=%s", subsystem) + 1;
-
+	for (j = 0; envp_ext && envp_ext[j]; j++)
+		envp[i++] = envp_ext[j];
 	/* just reserve the space, overwrite it after kset call has returned */
 	envp[i++] = seq_buff = scratch;
 	scratch += strlen("SEQNUM=18446744073709551616") + 1;
@@ -200,6 +206,20 @@ exit:
 	kfree(envp);
 	return;
 }
+
+EXPORT_SYMBOL_GPL(kobject_uevent_env);
+
+/**
+ * kobject_uevent - notify userspace by ending an uevent
+ *
+ * @action: action that is happening (usually KOBJ_ADD and KOBJ_REMOVE)
+ * @kobj: struct kobject that the action is happening to
+ */
+void kobject_uevent(struct kobject *kobj, enum kobject_action action)
+{
+	kobject_uevent_env(kobj, action, NULL);
+}
+
 EXPORT_SYMBOL_GPL(kobject_uevent);
 
 /**