From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261262AbVDINje (ORCPT ); Sat, 9 Apr 2005 09:39:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261316AbVDINjb (ORCPT ); Sat, 9 Apr 2005 09:39:31 -0400 Received: from coyote.holtmann.net ([217.160.111.169]:25495 "EHLO mail.holtmann.net") by vger.kernel.org with ESMTP id S261262AbVDINjW (ORCPT ); Sat, 9 Apr 2005 09:39:22 -0400 Subject: Re: [2.4] "Fix" introduced in 2.4.27pre2 for bluetooth hci_usb race causes kernel hang From: Marcel Holtmann To: Tomas =?ISO-8859-1?Q?=D6gren?= Cc: linux-kernel@vger.kernel.org In-Reply-To: <20050408195632.GA17621@shaka.acc.umu.se> References: <20050408195632.GA17621@shaka.acc.umu.se> Content-Type: multipart/mixed; boundary="=-/Hbxu+bezTzViuhP479G" Date: Sat, 09 Apr 2005 15:39:15 +0200 Message-Id: <1113053955.9783.57.camel@pegasus> Mime-Version: 1.0 X-Mailer: Evolution 2.2.1.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --=-/Hbxu+bezTzViuhP479G Content-Type: text/plain Content-Transfer-Encoding: 7bit Hi Tomas, > I have noticed a problem with a race condition fix introduced in > 2.4.27-pre2 that causes the kernel to hang when disconnecting a > Bluetooth USB dongle or doing 'hciconfig hci0 down'. No message is > printed, the kernel just doesn't respond anymore. > > Seen in Changelog: > Marcel Holtmann: > o [Bluetooth] Fix race in RX complete routine of the USB drivers > > Reversing the following patch to hci_usb_rx_complete() makes 2.4.27-pre2 > up until 2.4.30 happy and does not hang when removing the dongle > anymore. (bfusb.c has the same patch applied) > > 2.6.11.7 does not show the same problem, but has similar code to the > "fixed" (that hangs) code in 2.4, so the real problem is probably > somewhere else. does the attached patch makes any difference? Regards Marcel --=-/Hbxu+bezTzViuhP479G Content-Disposition: attachment; filename=patch Content-Type: text/plain; name=patch; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit ===== drivers/bluetooth/hci_usb.c 1.23 vs edited ===== --- 1.23/drivers/bluetooth/hci_usb.c 2004-07-31 13:02:43 +02:00 +++ edited/drivers/bluetooth/hci_usb.c 2005-04-09 15:37:12 +02:00 @@ -398,12 +398,12 @@ BT_DBG("%s", hdev->name); + /* Synchronize with completion handlers */ write_lock_irqsave(&husb->completion_lock, flags); - + write_unlock_irqrestore(&husb->completion_lock, flags); + hci_usb_unlink_urbs(husb); hci_usb_flush(hdev); - - write_unlock_irqrestore(&husb->completion_lock, flags); MOD_DEC_USE_COUNT; return 0; --=-/Hbxu+bezTzViuhP479G--