From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759426Ab2GLWgj (ORCPT ); Thu, 12 Jul 2012 18:36:39 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:45444 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759416Ab2GLWge (ORCPT ); Thu, 12 Jul 2012 18:36:34 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg KH , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Hiroaki SHIMODA , Tom Herbert , Eric Dumazet , Denys Fedoryshchenko , Eric Dumazet , "David S. Miller" Subject: [ 018/187] bql: Avoid possible inconsistent calculation. Date: Thu, 12 Jul 2012 15:32:54 -0700 Message-Id: <20120712191523.944857458@linuxfoundation.org> X-Mailer: git-send-email 1.7.10.1.362.g242cab3 In-Reply-To: <20120712191522.742634173@linuxfoundation.org> References: <20120712192421.GA28926@kroah.com> <20120712191522.742634173@linuxfoundation.org> User-Agent: quilt/0.60-20.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg KH 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hiroaki SHIMODA [ Upstream commit 914bec1011a25f65cdc94988a6f974bfb9a3c10d ] dql->num_queued could change while processing dql_completed(). To provide consistent calculation, added an on stack variable. Signed-off-by: Hiroaki SHIMODA Cc: Tom Herbert Cc: Eric Dumazet Cc: Denys Fedoryshchenko Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- lib/dynamic_queue_limits.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) --- a/lib/dynamic_queue_limits.c +++ b/lib/dynamic_queue_limits.c @@ -17,16 +17,18 @@ void dql_completed(struct dql *dql, unsigned int count) { unsigned int inprogress, prev_inprogress, limit; - unsigned int ovlimit, completed; + unsigned int ovlimit, completed, num_queued; bool all_prev_completed; + num_queued = ACCESS_ONCE(dql->num_queued); + /* Can't complete more than what's in queue */ - BUG_ON(count > dql->num_queued - dql->num_completed); + BUG_ON(count > num_queued - dql->num_completed); completed = dql->num_completed + count; limit = dql->limit; - ovlimit = POSDIFF(dql->num_queued - dql->num_completed, limit); - inprogress = dql->num_queued - completed; + ovlimit = POSDIFF(num_queued - dql->num_completed, limit); + inprogress = num_queued - completed; prev_inprogress = dql->prev_num_queued - dql->num_completed; all_prev_completed = AFTER_EQ(completed, dql->prev_num_queued); @@ -106,7 +108,7 @@ void dql_completed(struct dql *dql, unsi dql->prev_ovlimit = ovlimit; dql->prev_last_obj_cnt = dql->last_obj_cnt; dql->num_completed = completed; - dql->prev_num_queued = dql->num_queued; + dql->prev_num_queued = num_queued; } EXPORT_SYMBOL(dql_completed);