Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763382AbZAOK2j (ORCPT ); Thu, 15 Jan 2009 05:28:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763615AbZAOK2V (ORCPT ); Thu, 15 Jan 2009 05:28:21 -0500 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:58930 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760283AbZAOK2U (ORCPT ); Thu, 15 Jan 2009 05:28:20 -0500 Date: Thu, 15 Jan 2009 19:27:12 +0900 From: KAMEZAWA Hiroyuki To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "menage@google.com" , "lizf@cn.fujitsu.com" , "balbir@linux.vnet.ibm.com" , "nishimura@mxp.nes.nec.co.jp" , "akpm@linux-foundation.org" Subject: [PATCH 2/4] cgroup:add css_is_populated Message-Id: <20090115192712.33b533c3.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090115192120.9956911b.kamezawa.hiroyu@jp.fujitsu.com> References: <20090115192120.9956911b.kamezawa.hiroyu@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2104 Lines: 61 From: KAMEZAWA Hiroyuki cgroup creation is done in several stages. After allocated and linked to cgroup's hierarchy tree, all necessary control files are created. When using CSS_ID, scanning cgroups without cgrouo_lock(), status of cgroup is important. At removal of cgroup/css, css_tryget() works fine and we can write a safe code. At creation, we need some flag to show "This cgroup is not ready yet" This patch adds CSS_POPULATED flag. Signed-off-by: KAMEZAWA Hiroyuki --- Index: mmotm-2.6.29-Jan14/include/linux/cgroup.h =================================================================== --- mmotm-2.6.29-Jan14.orig/include/linux/cgroup.h +++ mmotm-2.6.29-Jan14/include/linux/cgroup.h @@ -69,6 +69,7 @@ struct cgroup_subsys_state { enum { CSS_ROOT, /* This CSS is the root of the subsystem */ CSS_REMOVED, /* This CSS is dead */ + CSS_POPULATED, /* This CSS finished all initialization */ }; /* @@ -90,6 +91,11 @@ static inline bool css_is_removed(struct return test_bit(CSS_REMOVED, &css->flags); } +static inline bool css_is_populated(struct cgroup_subsys_state *css) +{ + return test_bit(CSS_POPULATED, &css->flags); +} + /* * Call css_tryget() to take a reference on a css if your existing * (known-valid) reference isn't already ref-counted. Returns false if Index: mmotm-2.6.29-Jan14/kernel/cgroup.c =================================================================== --- mmotm-2.6.29-Jan14.orig/kernel/cgroup.c +++ mmotm-2.6.29-Jan14/kernel/cgroup.c @@ -2326,8 +2326,10 @@ static int cgroup_populate_dir(struct cg } for_each_subsys(cgrp->root, ss) { + struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; if (ss->populate && (err = ss->populate(ss, cgrp)) < 0) return err; + set_bit(CSS_POPULATED, &css->flags); } return 0; -- 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/