driver model: simplify device/driver binding.

- move list walking and matching to bus.c (since it's a function of the bus driver)
- do specialized walks of the bus's lists when binding; no more callbacks being passed
  to bus_for_each_*.
- take rwsem when adding and removing both devices and drivers. lists of each are now
  fully protected by that rwsem. It's also taken before we walk each list.
- move calls of device_{de,at}tach() to bus_{add,remove}_device() and calls of 
  driver_{de,at}tach() to bus_{add,remove}_driver().

drivers/base/base.h

@@ -20,6 +20,9 @@ extern void device_remove_dir(struct device * dev);
 extern int bus_make_dir(struct bus_type * bus);
 extern void bus_remove_dir(struct bus_type * bus);
 
+extern int bus_add_driver(struct device_driver *);
+extern void bus_remove_driver(struct device_driver *);
+
 extern int driver_make_dir(struct device_driver * drv);
 extern void driver_remove_dir(struct device_driver * drv);
 
@@ -48,9 +51,6 @@ extern int interface_add(struct device_class *, struct device *);
 extern void interface_remove(struct device_class *, struct device *);
 
 
-extern int driver_attach(struct device_driver * drv);
-extern void driver_detach(struct device_driver * drv);
-
 #ifdef CONFIG_HOTPLUG
 extern int dev_hotplug(struct device *dev, const char *action);
 #else

drivers/base/bus.c

@@ -94,6 +94,104 @@ int bus_for_each_drv(struct bus_type * bus, void * data,
 	return error;
 }
 
+static void attach(struct device * dev)
+{
+	pr_debug("bound device '%s' to driver '%s'\n",
+		 dev->bus_id,dev->driver->name);
+	list_add_tail(&dev->driver_list,&dev->driver->devices);
+}
+
+static int bus_match(struct device * dev, struct device_driver * drv)
+{
+	int error = 0;
+	if (dev->bus->match(dev,drv)) {
+		dev->driver = drv;
+		if (drv->probe) {
+			if (!(error = drv->probe(dev)))
+				attach(dev);
+			else
+				dev->driver = NULL;
+		}
+	}
+	return error;
+}
+
+static int device_attach(struct device * dev)
+{
+	struct bus_type * bus = dev->bus;
+	struct list_head * entry;
+	int error = 0;
+
+	if (dev->driver) {
+		attach(dev);
+		return 0;
+	}
+
+	if (!bus->match)
+		return 0;
+
+	list_for_each(entry,&bus->drivers) {
+		struct device_driver * drv = 
+			get_driver(container_of(entry,struct device_driver,bus_list));
+		if (!drv)
+			continue;
+		error = bus_match(dev,drv);
+		put_driver(drv);
+		if (!error)
+			break;
+	}
+	return error;
+}
+
+static int driver_attach(struct device_driver * drv)
+{
+	struct bus_type * bus = drv->bus;
+	struct list_head * entry;
+	int error = 0;
+
+	if (!bus->match)
+		return 0;
+
+	list_for_each(entry,&bus->devices) {
+		struct device * dev = container_of(entry,struct device,bus_list);
+		if (get_device(dev)) {
+			if (!bus_match(dev,drv) && dev->driver)
+				devclass_add_device(dev);
+			put_device(dev);
+		}
+	}
+	return error;
+}
+
+static void detach(struct device * dev, struct device_driver * drv)
+{
+	if (drv) {
+		list_del_init(&dev->driver_list);
+		devclass_remove_device(dev);
+		if (drv->remove)
+			drv->remove(dev);
+		dev->driver = NULL;
+	}
+}
+
+static void device_detach(struct device * dev)
+{
+	detach(dev,dev->driver);
+}
+
+static void driver_detach(struct device_driver * drv)
+{
+	struct list_head * entry;
+	list_for_each(entry,&drv->devices) {
+		struct device * dev = container_of(entry,struct device,driver_list);
+		if (get_device(dev)) {
+			detach(dev,drv);
+			put_device(dev);
+		}
+	}
+	
+}
+
 /**
  * bus_add_device - add device to bus
  * @dev:	device being added
@@ -105,11 +203,12 @@ int bus_for_each_drv(struct bus_type * bus, void * data,
  */
 int bus_add_device(struct device * dev)
 {
-	if (dev->bus) {
+	struct bus_type * bus = get_bus(dev->bus);
+	if (bus) {
 		down_write(&dev->bus->rwsem);
-		pr_debug("registering %s with bus '%s'\n",dev->bus_id,dev->bus->name);
-		get_bus(dev->bus);
+		pr_debug("bus %s: add device %s\n",bus->name,dev->bus_id);
 		list_add_tail(&dev->bus_list,&dev->bus->devices);
+		device_attach(dev);
 		up_write(&dev->bus->rwsem);
 		device_bus_link(dev);
 	}
@@ -127,13 +226,40 @@ void bus_remove_device(struct device * dev)
 {
 	if (dev->bus) {
 		down_write(&dev->bus->rwsem);
-		list_del_init(&dev->bus_list);
+		pr_debug("bus %s: remove device %s\n",dev->bus->name,dev->bus_id);
 		device_remove_symlink(&dev->bus->device_dir,dev->bus_id);
+		device_detach(dev);
+		list_del_init(&dev->bus_list);
 		up_write(&dev->bus->rwsem);
 		put_bus(dev->bus);
 	}
 }
 
+int bus_add_driver(struct device_driver * drv)
+{
+	struct bus_type * bus = get_bus(drv->bus);
+	if (bus) {
+		down_write(&bus->rwsem);
+		pr_debug("bus %s: add driver %s\n",bus->name,drv->name);
+		list_add_tail(&drv->bus_list,&bus->drivers);
+		driver_attach(drv);
+		up_write(&bus->rwsem);
+		driver_make_dir(drv);
+	}
+	return 0;
+}
+
+void bus_remove_driver(struct device_driver * drv)
+{
+	if (drv->bus) {
+		down_write(&drv->bus->rwsem);
+		pr_debug("bus %s: remove driver %s\n",drv->bus->name,drv->name);
+		driver_detach(drv);
+		list_del_init(&drv->bus_list);
+		up_write(&drv->bus->rwsem);
+	}
+}
+
 struct bus_type * get_bus(struct bus_type * bus)
 {
 	struct bus_type * ret = bus;

drivers/base/core.c

@@ -23,132 +23,6 @@ spinlock_t device_lock = SPIN_LOCK_UNLOCKED;
 
 #define to_dev(node) container_of(node,struct device,driver_list)
 
-static int probe(struct device * dev, struct device_driver * drv)
-{
-	dev->driver = drv;
-	return drv->probe ? drv->probe(dev) : 0;
-}
-
-static void attach(struct device * dev)
-{
-	spin_lock(&device_lock);
-	list_add_tail(&dev->driver_list,&dev->driver->devices);
-	spin_unlock(&device_lock);
-	devclass_add_device(dev);
-}
-
-/**
- * found_match - do actual binding of device to driver
- * @dev:	device 
- * @drv:	driver
- *
- * We're here because the bus's match callback returned success for this 
- * pair. We call the driver's probe callback to verify they're really a
- * match made in heaven.
- *
- * In the future, we may want to notify userspace of the binding. (But, 
- * we might not want to do it here).
- * 
- * We may also want to create a symlink in the driver's directory to the 
- * device's physical directory.
- */
-static int found_match(struct device * dev, struct device_driver * drv)
-{
-	int error = 0;
-
-	if (!(error = probe(dev,get_driver(drv)))) {
-		pr_debug("bound device '%s' to driver '%s'\n",
-			 dev->bus_id,drv->name);
-		attach(dev);
-	} else {
-		put_driver(drv);
-		dev->driver = NULL;
-	}
-	return error;
-}
-
-/**
- * device_attach - try to associated device with a driver
- * @drv:	current driver to try
- * @data:	device in disguise
- *
- * This function is used as a callback to bus_for_each_drv.
- * It calls the bus's match callback to check if the driver supports
- * the device. If so, it calls the found_match() function above to 
- * take care of all the details.
- */
-static int do_device_attach(struct device_driver * drv, void * data)
-{
-	struct device * dev = (struct device *)data;
-	int error = 0;
-
-	if (drv->bus->match && drv->bus->match(dev,drv))
-		error = found_match(dev,drv);
-	return error;
-}
-
-static int device_attach(struct device * dev)
-{
-	int error = 0;
-	if (!dev->driver) {
-		if (dev->bus)
-			error = bus_for_each_drv(dev->bus,dev,do_device_attach);
-	} else
-		attach(dev);
-	return error;
-}
-
-static void device_detach(struct device * dev)
-{
-	struct device_driver * drv = dev->driver;
-
-	if (drv) {
-		devclass_remove_device(dev);
-		if (drv && drv->remove)
-			drv->remove(dev);
-		dev->driver = NULL;
-	}
-}
-
-static int do_driver_attach(struct device * dev, void * data)
-{
-	struct device_driver * drv = (struct device_driver *)data;
-	int error = 0;
-
-	if (!dev->driver) {
-		if (dev->bus->match && dev->bus->match(dev,drv))
-			error = found_match(dev,drv);
-	}
-	return error;
-}
-
-int driver_attach(struct device_driver * drv)
-{
-	return bus_for_each_dev(drv->bus,drv,do_driver_attach);
-}
-
-void driver_detach(struct device_driver * drv)
-{
-	struct list_head * node;
-	struct device * prev = NULL;
-
-	spin_lock(&device_lock);
-	list_for_each(node,&drv->devices) {
-		struct device * dev = get_device_locked(to_dev(node));
-		if (dev) {
-			if (prev)
-				list_del_init(&prev->driver_list);
-			spin_unlock(&device_lock);
-			device_detach(dev);
-			if (prev)
-				put_device(prev);
-			prev = dev;
-			spin_lock(&device_lock);
-		}
-	}
-	spin_unlock(&device_lock);
-}
-
 int device_add(struct device *dev)
 {
 	int error;
@@ -173,9 +47,6 @@ int device_add(struct device *dev)
 
 	bus_add_device(dev);
 
-	/* bind to driver */
-	device_attach(dev);
-
 	/* notify platform of device entry */
 	if (platform_notify)
 		platform_notify(dev);
@@ -183,6 +54,7 @@ int device_add(struct device *dev)
 	/* notify userspace of device entry */
 	dev_hotplug(dev, "add");
 
+	devclass_add_device(dev);
  register_done:
 	if (error) {
 		spin_lock(&device_lock);
@@ -284,7 +156,6 @@ void device_del(struct device * dev)
 	/* notify userspace that this device is about to disappear */
 	dev_hotplug (dev, "remove");
 
-	device_detach(dev);
 	bus_remove_device(dev);
 
 	/* remove the driverfs directory */

drivers/base/driver.c

@@ -66,11 +66,9 @@ void put_driver(struct device_driver * drv)
 	struct bus_type * bus = drv->bus;
 	if (!atomic_dec_and_lock(&drv->refcount,&device_lock))
 		return;
-	list_del_init(&drv->bus_list);
 	spin_unlock(&device_lock);
 	BUG_ON(drv->present);
-	driver_detach(drv);
-	driver_remove_dir(drv);
+	bus_remove_driver(drv);
 	if (drv->release)
 		drv->release(drv);
 	put_bus(bus);
@@ -94,11 +92,7 @@ int driver_register(struct device_driver * drv)
 	rwlock_init(&drv->lock);
 	INIT_LIST_HEAD(&drv->devices);
 	drv->present = 1;
-	spin_lock(&device_lock);
-	list_add(&drv->bus_list,&drv->bus->drivers);
-	spin_unlock(&device_lock);
-	driver_make_dir(drv);
-	driver_attach(drv);
+	bus_add_driver(drv);
 	put_driver(drv);
 	return 0;
 }