Driver core: fix "driver" symlink timing

Create the "driver" link before the child device may be created by
the probing logic. This makes it possible for userspace (udev), to
determine the driver property of the parent device, at the time the
child device is created.

Signed-off-by: Kay Sievers <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/base/dd.c

···
 #define to_drv(node) container_of(node, struct device_driver, kobj.entry)
 
 
+static void driver_bound(struct device *dev)
+{
+	if (klist_node_attached(&dev->knode_driver)) {
+		printk(KERN_WARNING "%s: device %s already bound\n",
+			__FUNCTION__, kobject_name(&dev->kobj));
+		return;
+	}
+
+	pr_debug("bound device '%s' to driver '%s'\n",
+		 dev->bus_id, dev->driver->name);
+
+	if (dev->bus)
+		blocking_notifier_call_chain(&dev->bus->bus_notifier,
+					     BUS_NOTIFY_BOUND_DRIVER, dev);
+
+	klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
+}
+
+static int driver_sysfs_add(struct device *dev)
+{
+	int ret;
+
+	ret = sysfs_create_link(&dev->driver->kobj, &dev->kobj,
+			  kobject_name(&dev->kobj));
+	if (ret == 0) {
+		ret = sysfs_create_link(&dev->kobj, &dev->driver->kobj,
+					"driver");
+		if (ret)
+			sysfs_remove_link(&dev->driver->kobj,
+					kobject_name(&dev->kobj));
+	}
+	return ret;
+}
+
+static void driver_sysfs_remove(struct device *dev)
+{
+	struct device_driver *drv = dev->driver;
+
+	if (drv) {
+		sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
+		sysfs_remove_link(&dev->kobj, "driver");
+	}
+}
+
 /**
  *	device_bind_driver - bind a driver to one device.
  *	@dev:	device.
···
  */
 int device_bind_driver(struct device *dev)
 {
-	int ret;
-
-	if (klist_node_attached(&dev->knode_driver)) {
-		printk(KERN_WARNING "%s: device %s already bound\n",
-			__FUNCTION__, kobject_name(&dev->kobj));
-		return 0;
-	}
-
-	pr_debug("bound device '%s' to driver '%s'\n",
-		 dev->bus_id, dev->driver->name);
-
-	if (dev->bus)
-		blocking_notifier_call_chain(&dev->bus->bus_notifier,
-					     BUS_NOTIFY_BOUND_DRIVER, dev);
-
-	klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
-	ret = sysfs_create_link(&dev->driver->kobj, &dev->kobj,
-			  kobject_name(&dev->kobj));
-	if (ret == 0) {
-		ret = sysfs_create_link(&dev->kobj, &dev->driver->kobj,
-					"driver");
-		if (ret)
-			sysfs_remove_link(&dev->driver->kobj,
-					kobject_name(&dev->kobj));
-	}
-	return ret;
+	driver_bound(dev);
+	return driver_sysfs_add(dev);
 }
 
 struct stupid_thread_structure {
···
 		 drv->bus->name, drv->name, dev->bus_id);
 
 	dev->driver = drv;
+	if (driver_sysfs_add(dev)) {
+		printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
+			__FUNCTION__, dev->bus_id);
+		goto probe_failed;
+	}
+
 	if (dev->bus->probe) {
 		ret = dev->bus->probe(dev);
-		if (ret) {
-			dev->driver = NULL;
+		if (ret)
 			goto probe_failed;
-		}
 	} else if (drv->probe) {
 		ret = drv->probe(dev);
-		if (ret) {
-			dev->driver = NULL;
+		if (ret)
 			goto probe_failed;
-		}
 	}
-	if (device_bind_driver(dev)) {
-		printk(KERN_ERR "%s: device_bind_driver(%s) failed\n",
-			__FUNCTION__, dev->bus_id);
-		/* How does undo a ->probe?  We're screwed. */
-	}
+
+	driver_bound(dev);
 	ret = 1;
 	pr_debug("%s: Bound Device %s to Driver %s\n",
 		 drv->bus->name, dev->bus_id, drv->name);
 	goto done;
 
 probe_failed:
+	driver_sysfs_remove(dev);
+	dev->driver = NULL;
+
 	if (ret == -ENODEV || ret == -ENXIO) {
 		/* Driver matched, but didn't support device
 		 * or device not found.
···
 	drv = dev->driver;
 	if (drv) {
 		get_driver(drv);
-		sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
+		driver_sysfs_remove(dev);
 		sysfs_remove_link(&dev->kobj, "driver");
 		klist_remove(&dev->knode_driver);