Re: [patch]race condition in btusb disconnect() handling

[Oliver Neukum <oliver@neukum.org>]

Am Dienstag 19 August 2008 15:28:26 schrieb Marcel Holtmann:
> > First you release the interface, then you unregister the hci.
> 
> Putting it after hci_unregister_dev is an issue. The unregister will
> call __hci_dev_put and then in return will call the destruct callback
> which will free the data pointer.
> 
> So either we use hci_dev_hold or make sure that disconnect can only
> disable the SCO interface. That comes directly with the first comment
> from you.

Here is a new version. I am afraid normal hci_dev_hold would fail if
the disconnect happens because the btusb module is being unloaded.

	Regards
		Oliver

Signed-off-by: Oliver Neukum <oneukum@suse.de>

----

--- linux-2.6.27-rc3/drivers/bluetooth/btusb.c.marcel	2008-08-19 10:21:51.000000000 +0200
+++ linux-2.6.27-rc3/drivers/bluetooth/btusb.c	2008-08-19 15:50:06.000000000 +0200
@@ -169,6 +169,7 @@ static struct usb_device_id blacklist_ta
 struct btusb_data {
 	struct hci_dev       *hdev;
 	struct usb_device    *udev;
+	struct usb_interface *acl;
 	struct usb_interface *isoc;
 
 	spinlock_t lock;
@@ -523,6 +524,14 @@ static int btusb_open(struct hci_dev *hd
 	return err;
 }
 
+static void btusb_stop_traffic(struct btusb_data *data)
+{
+	usb_kill_anchored_urbs(&data->intr_anchor);
+	usb_kill_anchored_urbs(&data->bulk_anchor);
+	usb_kill_anchored_urbs(&data->isoc_anchor);
+	usb_kill_anchored_urbs(&data->tx_anchor);
+}
+
 static int btusb_close(struct hci_dev *hdev)
 {
 	struct btusb_data *data = hdev->driver_data;
@@ -535,13 +544,9 @@ static int btusb_close(struct hci_dev *h
 	flush_work(&data->work);
 
 	clear_bit(BTUSB_ISOC_RUNNING, &data->flags);
-	usb_kill_anchored_urbs(&data->intr_anchor);
-
 	clear_bit(BTUSB_BULK_RUNNING, &data->flags);
-	usb_kill_anchored_urbs(&data->bulk_anchor);
-
 	clear_bit(BTUSB_INTR_RUNNING, &data->flags);
-	usb_kill_anchored_urbs(&data->intr_anchor);
+	btusb_stop_traffic(data);
 
 	return 0;
 }
@@ -822,6 +827,7 @@ static int btusb_probe(struct usb_interf
 	}
 
 	data->udev = interface_to_usbdev(intf);
+	data->acl = intf;
 
 	spin_lock_init(&data->lock);
 
@@ -890,7 +896,7 @@ static int btusb_probe(struct usb_interf
 
 	if (data->isoc) {
 		err = usb_driver_claim_interface(&btusb_driver,
-							data->isoc, NULL);
+							data->isoc, data);
 		if (err < 0) {
 			hci_free_dev(hdev);
 			kfree(data);
@@ -922,13 +928,23 @@ static void btusb_disconnect(struct usb_
 
 	hdev = data->hdev;
 
-	if (data->isoc)
-		usb_driver_release_interface(&btusb_driver, data->isoc);
+	/* make sure we have a reference */
+	__hci_dev_hold(hdev);
 
-	usb_set_intfdata(intf, NULL);
+	usb_set_intfdata(data->acl, NULL);
+	if (data->isoc)
+		usb_set_intfdata(data->isoc, NULL);
 
+	/* unregister before releasing any interface */
 	hci_unregister_dev(hdev);
 
+	if (intf == data->isoc)
+		usb_driver_release_interface(&btusb_driver, data->acl);
+	else if (data->isoc)
+		usb_driver_release_interface(&btusb_driver, data->isoc);
+
+	/* release the reference */
+	__hci_dev_put(hdev);
 	hci_free_dev(hdev);
 }