Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753723Ab0DVJam (ORCPT ); Thu, 22 Apr 2010 05:30:42 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:52078 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752684Ab0DVJal (ORCPT ); Thu, 22 Apr 2010 05:30:41 -0400 Message-ID: <4BD017AC.1020209@cn.fujitsu.com> Date: Thu, 22 Apr 2010 17:32:28 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Thunderbird/3.0b2 MIME-Version: 1.0 To: LKML CC: "containers@lists.osdl.org" , "Paul E. McKenney" , Paul Menage , Andrew Morton , Jens Axboe , Vivek Goyal , Gui Jianfeng Subject: [PATCH 5/5] blk-cgroup: Fix an RCU warning in blkiocg_create() References: <4BD016F4.8060108@cn.fujitsu.com> In-Reply-To: <4BD016F4.8060108@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1454 Lines: 50 with CONFIG_PROVE_RCU=y, a warning can be triggered: # mount -t cgroup -o blkio xxx /mnt # mkdir /mnt/subgroup ... kernel/cgroup.c:4442 invoked rcu_dereference_check() without protection! ... To fix this, we avoid caling css_depth() here, which is a bit simpler than the original code. Signed-off-by: Li Zefan --- block/blk-cgroup.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 5fe03de..2cc682b 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -286,16 +286,16 @@ done: static struct cgroup_subsys_state * blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup) { - struct blkio_cgroup *blkcg, *parent_blkcg; + struct blkio_cgroup *blkcg; + struct cgroup *parent = cgroup->parent; - if (!cgroup->parent) { + if (!parent) { blkcg = &blkio_root_cgroup; goto done; } /* Currently we do not support hierarchy deeper than two level (0,1) */ - parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent); - if (css_depth(&parent_blkcg->css) > 0) + if (parent != cgroup->top_cgroup) return ERR_PTR(-EINVAL); blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); -- 1.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/