From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755541Ab0JVILN (ORCPT ); Fri, 22 Oct 2010 04:11:13 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:56931 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755325Ab0JVILK (ORCPT ); Fri, 22 Oct 2010 04:11:10 -0400 Message-ID: <4CC14756.5010504@cn.fujitsu.com> Date: Fri, 22 Oct 2010 16:12:06 +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: "akpm >> Andrew Morton" CC: Paul Menage , Stephane Eranian , LKML , containers@lists.linux-foundation.org Subject: [PATCH 6/7] cgroups: Warn if a bindable subsystem calls css_get() References: <4CC146A4.9090505@cn.fujitsu.com> In-Reply-To: <4CC146A4.9090505@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 For now bindable subsystems should not use css_get/put(), so warn on this misuse. Signed-off-by: Li Zefan --- include/linux/cgroup.h | 7 +++++-- kernel/cgroup.c | 3 +++ 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 1e4e1df..10e4e02 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -80,13 +80,15 @@ struct cgroup_subsys_state { /* bits in struct cgroup_subsys_state flags field */ enum { - CSS_ROOT, /* This CSS is the root of the subsystem */ - CSS_REMOVED, /* This CSS is dead */ + CSS_ROOT, /* This CSS is the root of the subsystem */ + CSS_REMOVED, /* This CSS is dead */ + CSS_NO_GET, /* Forbid calling css_get/put() */ }; /* Caller must verify that the css is not for root cgroup */ static inline void __css_get(struct cgroup_subsys_state *css, int count) { + BUG_ON(test_bit(CSS_NO_GET, &css->flags)); atomic_add(count, &css->refcnt); } @@ -119,6 +121,7 @@ static inline bool css_tryget(struct cgroup_subsys_state *css) { if (test_bit(CSS_ROOT, &css->flags)) return true; + BUG_ON(test_bit(CSS_NO_GET, &css->flags)); while (!atomic_inc_not_zero(&css->refcnt)) { if (test_bit(CSS_REMOVED, &css->flags)) return false; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 12c1f7c..88e265d 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -936,6 +936,9 @@ static void init_cgroup_css(struct cgroup_subsys_state *css, css->cgroup = cgrp; atomic_set(&css->refcnt, 1); css->flags = 0; + /* For now, a bindable subsystem should not call css_get/put(). */ + if (ss->can_bind) + set_bit(CSS_NO_GET, &css->flags); css->id = NULL; if (cgrp == dummytop) set_bit(CSS_ROOT, &css->flags); -- 1.7.0.1