#From foo@baz Tue Apr  9 12:12:43 2002
#Date: Thu, 01 Nov 2007 13:31:26 -0700
#To: Greg KH <greg@kroah.com>
#From: Greg Kroah-Hartman <gregkh@suse.de>
#Subject: driver core: remove fields from struct bus_type

DOES NOT BUILD AND IS NOT FULLY TESTED!!!

struct bus_type is static everywhere in the kernel.  This moves the
kobject in the structure out of it, and a bunch of other private only to
the driver core fields are now moved to a private structure.  This lets
us dynamically create the backing kobject properly and gives us the
chance to be able to document to users exactly how to use the struct
bus_type as there are no fields they can improperly access.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>


---
 drivers/base/base.h    |   30 ++++++++++++-
 drivers/base/bus.c     |  110 ++++++++++++++++++++++++++++---------------------
 drivers/base/core.c    |    6 +-
 include/linux/device.h |   12 -----
 4 files changed, 97 insertions(+), 61 deletions(-)

--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -1,6 +1,34 @@
 
-/* initialisation functions */
+/**
+ * struct bus_type_private - structure to hold the private to the driver core portions of the bus_type structure.
+ *
+ * @subsys - the struct kset that defines this bus.  This is the main kobject
+ * @drivers_kset - the list of drivers associated with this bus
+ * @devices_kset - the list of devices associated with this bus
+ * @klist_devices - the klist to iterate over the @devices_kset
+ * @klist_drivers - the klist to iterate over the @drivers_kset
+ * @bus_notifier - the bus notifier list for anything that cares about things
+ * on this bus.
+ * @bus - pointer back to the struct bus_type that this structure is associated
+ * with.
+ *
+ * This structure is the one that is the actual kobject allowing struct
+ * bus_type to be statically allocated safely.  Nothing outside of the driver
+ * core should ever touch these fields.
+ */
+struct bus_type_private {
+	struct kset subsys;
+	struct kset *drivers_kset;
+	struct kset *devices_kset;
+	struct klist klist_devices;
+	struct klist klist_drivers;
+	struct blocking_notifier_head bus_notifier;
+	unsigned int drivers_autoprobe:1;
+	struct bus_type *bus;
+};
+
 
+/* initialisation functions */
 extern int devices_init(void);
 extern int buses_init(void);
 extern int classes_init(void);
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -18,7 +18,7 @@
 #include "power/power.h"
 
 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
-#define to_bus(obj) container_of(obj, struct bus_type, subsys.kobj)
+#define to_bus(obj) container_of(obj, struct bus_type_private, subsys.kobj)
 
 /*
  * sysfs bindings for drivers
@@ -33,13 +33,17 @@ static int __must_check bus_rescan_devic
 
 static struct bus_type *bus_get(struct bus_type *bus)
 {
-	return bus ? container_of(kset_get(&bus->subsys),
-				struct bus_type, subsys) : NULL;
+	if (bus) {
+		kset_get(&bus->p->subsys);
+		return bus;
+	}
+	return NULL;
 }
 
 static void bus_put(struct bus_type *bus)
 {
-	kset_put(&bus->subsys);
+	if (bus)
+		kset_put(&bus->p->subsys);
 }
 
 static ssize_t
@@ -105,11 +109,11 @@ static ssize_t
 bus_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
 {
 	struct bus_attribute * bus_attr = to_bus_attr(attr);
-	struct bus_type * bus = to_bus(kobj);
+	struct bus_type_private *bus_priv = to_bus(kobj);
 	ssize_t ret = 0;
 
 	if (bus_attr->show)
-		ret = bus_attr->show(bus, buf);
+		ret = bus_attr->show(bus_priv->bus, buf);
 	return ret;
 }
 
@@ -118,11 +122,11 @@ bus_attr_store(struct kobject * kobj, st
 	       const char * buf, size_t count)
 {
 	struct bus_attribute * bus_attr = to_bus_attr(attr);
-	struct bus_type * bus = to_bus(kobj);
+	struct bus_type_private *bus_priv = to_bus(kobj);
 	ssize_t ret = 0;
 
 	if (bus_attr->store)
-		ret = bus_attr->store(bus, buf, count);
+		ret = bus_attr->store(bus_priv->bus, buf, count);
 	return ret;
 }
 
@@ -135,7 +139,7 @@ int bus_create_file(struct bus_type * bu
 {
 	int error;
 	if (bus_get(bus)) {
-		error = sysfs_create_file(&bus->subsys.kobj, &attr->attr);
+		error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
 		bus_put(bus);
 	} else
 		error = -EINVAL;
@@ -145,7 +149,7 @@ int bus_create_file(struct bus_type * bu
 void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
 {
 	if (bus_get(bus)) {
-		sysfs_remove_file(&bus->subsys.kobj, &attr->attr);
+		sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
 		bus_put(bus);
 	}
 }
@@ -238,16 +242,16 @@ static DRIVER_ATTR(bind, S_IWUSR, NULL, 
 
 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
 {
-	return sprintf(buf, "%d\n", bus->drivers_autoprobe);
+	return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
 }
 
 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
 				       const char *buf, size_t count)
 {
 	if (buf[0] == '0')
-		bus->drivers_autoprobe = 0;
+		bus->p->drivers_autoprobe = 0;
 	else
-		bus->drivers_autoprobe = 1;
+		bus->p->drivers_autoprobe = 1;
 	return count;
 }
 
@@ -301,7 +305,7 @@ int bus_for_each_dev(struct bus_type * b
 	if (!bus)
 		return -EINVAL;
 
-	klist_iter_init_node(&bus->klist_devices, &i,
+	klist_iter_init_node(&bus->p->klist_devices, &i,
 			     (start ? &start->knode_bus : NULL));
 	while ((dev = next_device(&i)) && !error)
 		error = fn(dev, data);
@@ -334,7 +338,7 @@ struct device * bus_find_device(struct b
 	if (!bus)
 		return NULL;
 
-	klist_iter_init_node(&bus->klist_devices, &i,
+	klist_iter_init_node(&bus->p->klist_devices, &i,
 			     (start ? &start->knode_bus : NULL));
 	while ((dev = next_device(&i)))
 		if (match(dev, data) && get_device(dev))
@@ -380,7 +384,7 @@ int bus_for_each_drv(struct bus_type * b
 	if (!bus)
 		return -EINVAL;
 
-	klist_iter_init_node(&bus->klist_drivers, &i,
+	klist_iter_init_node(&bus->p->klist_drivers, &i,
 			     start ? &start->knode_bus : NULL);
 	while ((drv = next_driver(&i)) && !error)
 		error = fn(drv, data);
@@ -450,12 +454,12 @@ int bus_add_device(struct device * dev)
 		error = device_add_attrs(bus, dev);
 		if (error)
 			goto out_put;
-		error = sysfs_create_link(&bus->devices_kset->kobj,
+		error = sysfs_create_link(&bus->p->devices_kset->kobj,
 						&dev->kobj, dev->bus_id);
 		if (error)
 			goto out_id;
 		error = sysfs_create_link(&dev->kobj,
-				&dev->bus->subsys.kobj, "subsystem");
+				&dev->bus->p->subsys.kobj, "subsystem");
 		if (error)
 			goto out_subsys;
 		error = make_deprecated_bus_links(dev);
@@ -467,7 +471,7 @@ int bus_add_device(struct device * dev)
 out_deprecated:
 	sysfs_remove_link(&dev->kobj, "subsystem");
 out_subsys:
-	sysfs_remove_link(&bus->devices_kset->kobj, dev->bus_id);
+	sysfs_remove_link(&bus->p->devices_kset->kobj, dev->bus_id);
 out_id:
 	device_remove_attrs(bus, dev);
 out_put:
@@ -493,7 +497,7 @@ void bus_attach_device(struct device * d
 			ret = device_attach(dev);
 		WARN_ON(ret < 0);
 		if (ret >= 0)
-			klist_add_tail(&dev->knode_bus, &bus->klist_devices);
+			klist_add_tail(&dev->knode_bus, &bus->p->klist_devices);
 		else
 			dev->is_registered = 0;
 	}
@@ -513,7 +517,7 @@ void bus_remove_device(struct device * d
 	if (dev->bus) {
 		sysfs_remove_link(&dev->kobj, "subsystem");
 		remove_deprecated_bus_links(dev);
-		sysfs_remove_link(&dev->bus->devices_kset->kobj, dev->bus_id);
+		sysfs_remove_link(&dev->bus->p->devices_kset->kobj, dev->bus_id);
 		device_remove_attrs(dev->bus, dev);
 		if (dev->is_registered) {
 			dev->is_registered = 0;
@@ -639,7 +643,7 @@ int bus_add_driver(struct device_driver 
 	error = kobject_set_name(&drv->kobj, "%s", drv->name);
 	if (error)
 		goto out_put_bus;
-	drv->kobj.kset = bus->drivers_kset;
+	drv->kobj.kset = bus->p->drivers_kset;
 	drv->kobj.ktype = &driver_ktype;
 	error = kobject_register(&drv->kobj);
 	if (error)
@@ -650,7 +654,7 @@ int bus_add_driver(struct device_driver 
 		if (error)
 			goto out_unregister;
 	}
-	klist_add_tail(&drv->knode_bus, &bus->klist_drivers);
+	klist_add_tail(&drv->knode_bus, &bus->p->klist_drivers);
 	module_add_driver(drv->owner, drv);
 
 	error = driver_create_file(drv, &driver_attr_uevent);
@@ -829,7 +833,7 @@ static ssize_t bus_uevent_store(struct b
 	enum kobject_action action;
 
 	if (kobject_action_type(buf, count, &action) == 0)
-		kobject_uevent(&bus->subsys.kobj, action);
+		kobject_uevent(&bus->p->subsys.kobj, action);
 	return count;
 }
 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
@@ -845,17 +849,25 @@ static BUS_ATTR(uevent, S_IWUSR, NULL, b
 int bus_register(struct bus_type * bus)
 {
 	int retval;
+	struct bus_type_private *priv;
+
+	priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->bus = bus;
+	bus->p = priv;
 
-	BLOCKING_INIT_NOTIFIER_HEAD(&bus->bus_notifier);
+	BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
 
-	retval = kobject_set_name(&bus->subsys.kobj, "%s", bus->name);
+	retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
 	if (retval)
 		goto out;
 
-	bus->subsys.kobj.kset = bus_kset;
-	bus->subsys.kobj.ktype = &bus_ktype;
+	priv->subsys.kobj.kset = bus_kset;
+	priv->subsys.kobj.ktype = &bus_ktype;
 
-	retval = subsystem_register(&bus->subsys);
+	retval = subsystem_register(&priv->subsys);
 	if (retval)
 		goto out;
 
@@ -863,22 +875,24 @@ int bus_register(struct bus_type * bus)
 	if (retval)
 		goto bus_uevent_fail;
 
-	bus->devices_kset = kset_create_and_register("devices", NULL,
-						     &bus->subsys.kobj, NULL);
-	if (IS_ERR(bus->devices_kset)) {
-		retval = PTR_ERR(bus->devices_kset);
+	priv->devices_kset = kset_create_and_register("devices", NULL,
+						      &priv->subsys.kobj,
+						      NULL);
+	if (IS_ERR(priv->devices_kset)) {
+		retval = PTR_ERR(priv->devices_kset);
 		goto bus_devices_fail;
 	}
 
-	bus->drivers_kset = kset_create_and_register("drivers", NULL,
-						     &bus->subsys.kobj, NULL);
-	if (IS_ERR(bus->drivers_kset)) {
-		retval = PTR_ERR(bus->drivers_kset);
+	priv->drivers_kset = kset_create_and_register("drivers", NULL,
+						      &priv->subsys.kobj,
+						      NULL);
+	if (IS_ERR(priv->drivers_kset)) {
+		retval = PTR_ERR(priv->drivers_kset);
 		goto bus_drivers_fail;
 	}
 
-	klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);
-	klist_init(&bus->klist_drivers, NULL, NULL);
+	klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
+	klist_init(&priv->klist_drivers, NULL, NULL);
 
 	bus->drivers_autoprobe = 1;
 	retval = add_probe_files(bus);
@@ -895,13 +909,14 @@ int bus_register(struct bus_type * bus)
 bus_attrs_fail:
 	remove_probe_files(bus);
 bus_probe_files_fail:
-	kset_unregister(bus->drivers_kset);
+	kset_unregister(bus->p->drivers_kset);
 bus_drivers_fail:
-	kset_unregister(bus->devices_kset);
+	kset_unregister(bus->p->devices_kset);
 bus_devices_fail:
 	bus_remove_file(bus, &bus_attr_uevent);
 bus_uevent_fail:
-	subsystem_unregister(&bus->subsys);
+	subsystem_unregister(&bus->p->subsys);
+	kfree(bus->p);
 out:
 	return retval;
 }
@@ -918,21 +933,22 @@ void bus_unregister(struct bus_type * bu
 	pr_debug("bus %s: unregistering\n", bus->name);
 	bus_remove_attrs(bus);
 	remove_probe_files(bus);
-	kset_unregister(bus->drivers_kset);
-	kset_unregister(bus->devices_kset);
+	kset_unregister(bus->p->drivers_kset);
+	kset_unregister(bus->p->devices_kset);
 	bus_remove_file(bus, &bus_attr_uevent);
-	subsystem_unregister(&bus->subsys);
+	subsystem_unregister(&bus->p->subsys);
+	kfree(bus->p);
 }
 
 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
 {
-	return blocking_notifier_chain_register(&bus->bus_notifier, nb);
+	return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
 }
 EXPORT_SYMBOL_GPL(bus_register_notifier);
 
 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
 {
-	return blocking_notifier_chain_unregister(&bus->bus_notifier, nb);
+	return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
 }
 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
 
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -762,7 +762,7 @@ int device_add(struct device *dev)
 
 	/* notify clients of device entry (new way) */
 	if (dev->bus)
-		blocking_notifier_call_chain(&dev->bus->bus_notifier,
+		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_ADD_DEVICE, dev);
 
 	error = device_create_file(dev, &uevent_attr);
@@ -811,7 +811,7 @@ int device_add(struct device *dev)
 	device_pm_remove(dev);
  PMError:
 	if (dev->bus)
-		blocking_notifier_call_chain(&dev->bus->bus_notifier,
+		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_DEL_DEVICE, dev);
 	device_remove_attrs(dev);
  AttrsError:
@@ -990,7 +990,7 @@ void device_del(struct device * dev)
 	if (platform_notify_remove)
 		platform_notify_remove(dev);
 	if (dev->bus)
-		blocking_notifier_call_chain(&dev->bus->bus_notifier,
+		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_DEL_DEVICE, dev);
 	device_pm_remove(dev);
 	kobject_uevent(&dev->kobj, KOBJ_REMOVE);
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -35,6 +35,7 @@ struct device_driver;
 struct class;
 struct class_device;
 struct bus_type;
+struct bus_type_private;
 
 struct bus_attribute {
 	struct attribute	attr;
@@ -51,15 +52,6 @@ extern void bus_remove_file(struct bus_t
 
 struct bus_type {
 	const char		* name;
-
-	struct kset		subsys;
-	struct kset		*drivers_kset;
-	struct kset		*devices_kset;
-	struct klist		klist_devices;
-	struct klist		klist_drivers;
-
-	struct blocking_notifier_head bus_notifier;
-
 	struct bus_attribute	* bus_attrs;
 	struct device_attribute	* dev_attrs;
 	struct driver_attribute	* drv_attrs;
@@ -75,7 +67,7 @@ struct bus_type {
 	int (*resume_early)(struct device * dev);
 	int (*resume)(struct device * dev);
 
-	unsigned int drivers_autoprobe:1;
+	struct bus_type_private *p;
 };
 
 extern int __must_check bus_register(struct bus_type * bus);