From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932141Ab1EFAYf (ORCPT ); Thu, 5 May 2011 20:24:35 -0400 Received: from kroah.org ([198.145.64.141]:36635 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754089Ab1EFAY3 (ORCPT ); Thu, 5 May 2011 20:24:29 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Thu May 5 17:22:07 2011 Message-Id: <20110506002207.894747486@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Thu, 05 May 2011 17:20:13 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, James Bottomley Subject: [028/143] [SCSI] put stricter guards on queue dead checks In-Reply-To: <20110506002311.GA15354@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let us know. ------------------ From: James Bottomley commit 86cbfb5607d4b81b1a993ff689bbd2addd5d3a9b upstream. SCSI uses request_queue->queuedata == NULL as a signal that the queue is dying. We set this state in the sdev release function. However, this allows a small window where we release the last reference but haven't quite got to this stage yet and so something will try to take a reference in scsi_request_fn and oops. It's very rare, but we had a report here, so we're pushing this as a bug fix The actual fix is to set request_queue->queuedata to NULL in scsi_remove_device() before we drop the reference. This causes correct automatic rejects from scsi_request_fn as people who hold additional references try to submit work and prevents anything from getting a new reference to the sdev that way. Signed-off-by: James Bottomley Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/scsi_sysfs.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -318,14 +318,8 @@ static void scsi_device_dev_release_user kfree(evt); } - if (sdev->request_queue) { - sdev->request_queue->queuedata = NULL; - /* user context needed to free queue */ - scsi_free_queue(sdev->request_queue); - /* temporary expedient, try to catch use of queue lock - * after free of sdev */ - sdev->request_queue = NULL; - } + /* NULL queue means the device can't be used */ + sdev->request_queue = NULL; scsi_target_reap(scsi_target(sdev)); @@ -925,6 +919,12 @@ void __scsi_remove_device(struct scsi_de if (sdev->host->hostt->slave_destroy) sdev->host->hostt->slave_destroy(sdev); transport_destroy_device(dev); + + /* cause the request function to reject all I/O requests */ + sdev->request_queue->queuedata = NULL; + + /* Freeing the queue signals to block that we're done */ + scsi_free_queue(sdev->request_queue); put_device(dev); }