From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756552Ab0LHAs2 (ORCPT ); Tue, 7 Dec 2010 19:48:28 -0500 Received: from kroah.org ([198.145.64.141]:58768 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756444Ab0LHAs0 (ORCPT ); Tue, 7 Dec 2010 19:48:26 -0500 X-Mailbox-Line: From gregkh@clark.site Tue Dec 7 16:44:36 2010 Message-Id: <20101208004436.833626647@clark.site> User-Agent: quilt/0.48-11.2 Date: Tue, 07 Dec 2010 16:45:11 -0800 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, Robin Holt , Jack Steiner , Ingo Molnar Subject: [125/127] x86: uv: XPC receive message reuse triggers invalid BUG_ON() In-Reply-To: <20101208004456.GA23578@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: Robin Holt commit 046d6c563b1c6226bbf0f84e5b2413ad8ab921a1 upstream. This was a difficult bug to trip. XPC was in the middle of sending an acknowledgement for a received message. In xpc_received_payload_uv(): . ret = xpc_send_gru_msg(ch->sn.uv.cached_notify_gru_mq_desc, msg, sizeof(struct xpc_notify_mq_msghdr_uv)); if (ret != xpSuccess) XPC_DEACTIVATE_PARTITION(&xpc_partitions[ch->partid], ret); msg->hdr.msg_slot_number += ch->remote_nentries; at the point in xpc_send_gru_msg() where the hardware has dispatched the acknowledgement, the remote side is able to reuse the message structure and send a message with a different slot number. This problem is made worse by interrupts. The adjustment of msg_slot_number and the BUG_ON in xpc_handle_notify_mq_msg_uv() which verifies the msg_slot_number is consistent are only used for debug purposes. Since a fix for this that preserves the debug functionality would either have to infringe upon the payload or allocate another structure just for debug, I decided to remove it entirely. Signed-off-by: Robin Holt Cc: Jack Steiner Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/misc/sgi-xp/xpc_uv.c | 3 --- 1 file changed, 3 deletions(-) --- a/drivers/misc/sgi-xp/xpc_uv.c +++ b/drivers/misc/sgi-xp/xpc_uv.c @@ -1441,7 +1441,6 @@ xpc_handle_notify_mq_msg_uv(struct xpc_p msg_slot = ch_uv->recv_msg_slots + (msg->hdr.msg_slot_number % ch->remote_nentries) * ch->entry_size; - BUG_ON(msg->hdr.msg_slot_number != msg_slot->hdr.msg_slot_number); BUG_ON(msg_slot->hdr.size != 0); memcpy(msg_slot, msg, msg->hdr.size); @@ -1665,8 +1664,6 @@ xpc_received_payload_uv(struct xpc_chann sizeof(struct xpc_notify_mq_msghdr_uv)); if (ret != xpSuccess) XPC_DEACTIVATE_PARTITION(&xpc_partitions[ch->partid], ret); - - msg->hdr.msg_slot_number += ch->remote_nentries; } static struct xpc_arch_operations xpc_arch_ops_uv = {