From 1901fb2604fbcd53201f38725182ea807581159e Mon Sep 17 00:00:00 2001
From: Kay Sievers <kay.sievers@novell.com>
Date: Sat, 7 Oct 2006 21:55:55 +0200
Subject: [PATCH] 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 <kay.sievers@novell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 drivers/base/dd.c | 98 +++++++++++++++++++++++++++++------------------
 1 file changed, 60 insertions(+), 38 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 9c88b1e34bc3..510e7884975f 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -26,6 +26,50 @@
 #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.
@@ -42,32 +86,8 @@
  */
 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 {
@@ -90,30 +110,32 @@ static int really_probe(void *void_data)
 		 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.
@@ -289,7 +311,7 @@ static void __device_release_driver(struct device * dev)
 	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);