From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761473Ab3BNQqq (ORCPT ); Thu, 14 Feb 2013 11:46:46 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:44237 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755903Ab3BNQqo (ORCPT ); Thu, 14 Feb 2013 11:46:44 -0500 From: Jerry Snitselaar To: linux-kernel@vger.kernel.org Cc: cgroups@vger.kernel.org, serge.hallyn@canonical.com, tj@kernel.org, aris@redhat.com Subject: [PATCH] device_cgroup: don't grab mutex in rcu callback Date: Thu, 14 Feb 2013 09:46:03 -0700 Message-Id: <1360860363-2879-1-git-send-email-jerry.snitselaar@oracle.com> X-Mailer: git-send-email 1.8.1.1.293.gfe73786 X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit 103a197 "security/device_cgroup: lock assert fails in dev_exception_clean()" grabs devcgroup_mutex to fix assert failure, but mutex can't be grabbed in rcu callback. Since there shouldn't be any other references when css_free is called, mutex isn't needed for list cleanup in devcgroup_css_free(). Signed-off-by: Jerry Snitselaar Acked-by: Tejun Heo Acked-by: Aristeu Rozanski --- security/device_cgroup.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/security/device_cgroup.c b/security/device_cgroup.c index d794abc..1c69e38 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -159,6 +159,16 @@ static void dev_exception_rm(struct dev_cgroup *dev_cgroup, } } +static void __dev_exception_clean(struct dev_cgroup *dev_cgroup) +{ + struct dev_exception_item *ex, *tmp; + + list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) { + list_del_rcu(&ex->list); + kfree_rcu(ex, rcu); + } +} + /** * dev_exception_clean - frees all entries of the exception list * @dev_cgroup: dev_cgroup with the exception list to be cleaned @@ -167,14 +177,9 @@ static void dev_exception_rm(struct dev_cgroup *dev_cgroup, */ static void dev_exception_clean(struct dev_cgroup *dev_cgroup) { - struct dev_exception_item *ex, *tmp; - lockdep_assert_held(&devcgroup_mutex); - list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) { - list_del_rcu(&ex->list); - kfree_rcu(ex, rcu); - } + __dev_exception_clean(dev_cgroup); } /* @@ -215,9 +220,7 @@ static void devcgroup_css_free(struct cgroup *cgroup) struct dev_cgroup *dev_cgroup; dev_cgroup = cgroup_to_devcgroup(cgroup); - mutex_lock(&devcgroup_mutex); - dev_exception_clean(dev_cgroup); - mutex_unlock(&devcgroup_mutex); + __dev_exception_clean(dev_cgroup); kfree(dev_cgroup); } -- 1.8.1.1.293.gfe73786