From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759546AbXKABwS (ORCPT ); Wed, 31 Oct 2007 21:52:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753432AbXKABwJ (ORCPT ); Wed, 31 Oct 2007 21:52:09 -0400 Received: from einhorn.in-berlin.de ([192.109.42.8]:58856 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752080AbXKABwH (ORCPT ); Wed, 31 Oct 2007 21:52:07 -0400 X-Envelope-From: stefanr@s5r6.in-berlin.de Date: Thu, 1 Nov 2007 02:51:44 +0100 (CET) From: Stefan Richter Subject: [PATCH] firewire: fw-sbp2: enforce read order of device generation and node ID To: linux1394-devel@lists.sourceforge.net cc: linux-kernel@vger.kernel.org, =?iso-8859-1?Q?Kristian_H=F8gsberg?= In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=us-ascii Content-Disposition: INLINE Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Two fixes: - There was a small window where a login or reconnect job could use an already updated card generation with an outdated node ID. We better use the fw_device.generation here, not the fw_card.generation. - Insert a memory barrier to ensure that the device generation is read before the node ID. This is to guarantee that the generation is not newer than the node ID. A small optimization: - The target's and initiator's node IDs can be obtained from fw_device and fw_card. Dereferencing their underlying topology objects is not necessary. Signed-off-by: Stefan Richter --- drivers/firewire/fw-sbp2.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) Index: linux/drivers/firewire/fw-sbp2.c =================================================================== --- linux.orig/drivers/firewire/fw-sbp2.c +++ linux/drivers/firewire/fw-sbp2.c @@ -643,9 +643,10 @@ static void sbp2_login(struct work_struc struct sbp2_login_response response; int generation, node_id, local_node_id; - generation = device->card->generation; - node_id = device->node->node_id; - local_node_id = device->card->local_node->node_id; + generation = device->generation; + rmb(); + node_id = device->node_id; + local_node_id = device->card->node_id; if (sbp2_send_management_orb(lu, node_id, generation, SBP2_LOGIN_REQUEST, lu->lun, &response) < 0) { @@ -900,9 +901,10 @@ static void sbp2_reconnect(struct work_s struct fw_device *device = fw_device(unit->device.parent); int generation, node_id, local_node_id; - generation = device->card->generation; - node_id = device->node->node_id; - local_node_id = device->card->local_node->node_id; + generation = device->generation; + rmb(); + node_id = device->node_id; + local_node_id = device->card->node_id; if (sbp2_send_management_orb(lu, node_id, generation, SBP2_RECONNECT_REQUEST, -- Stefan Richter -=====-=-=== =-== ----= http://arcgraph.de/sr/