[BLUETOOTH]: Move children of connection device to NULL before connection down.

The rfcomm tty device will possibly retain even when conn is down, and
sysfs doesn't support zombie device moving, so this patch move the tty
device before conn device is destroyed.

For the bug refered please see :
http://lkml.org/lkml/2007/12/28/87

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bluetooth/hci_sysfs.c

@@ -316,9 +316,26 @@ void hci_conn_add_sysfs(struct hci_conn *conn)
 	schedule_work(&conn->work);
 }
 
+static int __match_tty(struct device *dev, void *data)
+{
+	/* The rfcomm tty device will possibly retain even when conn
+	 * is down, and sysfs doesn't support move zombie device,
+	 * so we should move the device before conn device is destroyed.
+	 * Due to the only child device of hci_conn dev is rfcomm
+	 * tty_dev, here just return 1
+	 */
+	return 1;
+}
+
 static void del_conn(struct work_struct *work)
 {
+	struct device *dev;
 	struct hci_conn *conn = container_of(work, struct hci_conn, work);
+
+	while (dev = device_find_child(&conn->dev, NULL, __match_tty)) {
+		device_move(dev, NULL);
+		put_device(dev);
+	}
 	device_del(&conn->dev);
 	put_device(&conn->dev);
 }

net/bluetooth/rfcomm/tty.c

@@ -696,7 +696,8 @@ static void rfcomm_tty_close(struct tty_struct *tty, struct file *filp)
 	BT_DBG("tty %p dev %p dlc %p opened %d", tty, dev, dev->dlc, dev->opened);
 
 	if (--dev->opened == 0) {
-		device_move(dev->tty_dev, NULL);
+		if (dev->tty_dev->parent)
+			device_move(dev->tty_dev, NULL);
 
 		/* Close DLC and dettach TTY */
 		rfcomm_dlc_close(dev->dlc, 0);