From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Oliver Neukum To: Marcel Holtmann Subject: Re: [patch]race condition in btusb disconnect() handling Date: Tue, 19 Aug 2008 16:05:40 +0200 Cc: linux-bluetooth@vger.kernel.org, linux-usb@vger.kernel.org References: <200808191423.52657.oliver@neukum.org> <200808191509.00705.oliver@neukum.org> <1219152506.7591.142.camel@violet.holtmann.net> In-Reply-To: <1219152506.7591.142.camel@violet.holtmann.net> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Message-Id: <200808191605.40987.oliver@neukum.org> List-ID: 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 ---- --- 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); }