From patchwork Sat Jan 26 04:42:22 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zefan Li X-Patchwork-Id: 215885 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id E84BF2C007E for ; Sat, 26 Jan 2013 15:42:36 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751086Ab3AZEme (ORCPT ); Fri, 25 Jan 2013 23:42:34 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:38987 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750907Ab3AZEmd (ORCPT ); Fri, 25 Jan 2013 23:42:33 -0500 Received: from 172.24.2.119 (EHLO szxeml211-edg.china.huawei.com) ([172.24.2.119]) by szxrg02-dlp.huawei.com (MOS 4.3.4-GA FastPath queued) with ESMTP id AWF36204; Sat, 26 Jan 2013 12:42:30 +0800 (CST) Received: from SZXEML410-HUB.china.huawei.com (10.82.67.137) by szxeml211-edg.china.huawei.com (172.24.2.182) with Microsoft SMTP Server (TLS) id 14.1.323.7; Sat, 26 Jan 2013 12:42:22 +0800 Received: from [10.135.68.215] (10.135.68.215) by smtpscn.huawei.com (10.82.67.137) with Microsoft SMTP Server (TLS) id 14.1.323.7; Sat, 26 Jan 2013 12:42:23 +0800 Message-ID: <51035EAE.5090004@huawei.com> Date: Sat, 26 Jan 2013 12:42:22 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130107 Thunderbird/17.0.2 MIME-Version: 1.0 To: David Miller CC: , Gao feng , John Fastabend , Neil Horman Subject: [PATCH 3.4.y 3/3] net: netprio: fix cgrp create and write priomap race References: <51035E4F.6030508@huawei.com> In-Reply-To: <51035E4F.6030508@huawei.com> X-Originating-IP: [10.135.68.215] X-CFilter-Loop: Reflected Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: John Fastabend commit 476ad154f3b41dd7d9a08a2f641e28388abc2fd1 upstream. A race exists where creating cgroups and also updating the priomap may result in losing a priomap update. This is because priomap writers are not protected by rtnl_lock. Move priority writer into rtnl_lock()/rtnl_unlock(). CC: Neil Horman Reported-by: Al Viro Signed-off-by: John Fastabend Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Li Zefan --- net/core/netprio_cgroup.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/net/core/netprio_cgroup.c b/net/core/netprio_cgroup.c index dca347e..eb07ea9 100644 --- a/net/core/netprio_cgroup.c +++ b/net/core/netprio_cgroup.c @@ -112,12 +112,10 @@ static int write_update_netdev_table(struct net_device *dev) u32 max_len; struct netprio_map *map; - rtnl_lock(); max_len = atomic_read(&max_prioidx) + 1; map = rtnl_dereference(dev->priomap); if (!map || map->priomap_len < max_len) ret = extend_netdev_table(dev, max_len); - rtnl_unlock(); return ret; } @@ -267,17 +265,17 @@ static int write_priomap(struct cgroup *cgrp, struct cftype *cft, if (!dev) goto out_free_devname; + rtnl_lock(); ret = write_update_netdev_table(dev); if (ret < 0) goto out_put_dev; - rcu_read_lock(); - map = rcu_dereference(dev->priomap); + map = rtnl_dereference(dev->priomap); if (map) map->priomap[prioidx] = priority; - rcu_read_unlock(); out_put_dev: + rtnl_unlock(); dev_put(dev); out_free_devname: