Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756893AbZAPDBW (ORCPT ); Thu, 15 Jan 2009 22:01:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751913AbZAPDBN (ORCPT ); Thu, 15 Jan 2009 22:01:13 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:51118 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751486AbZAPDBM (ORCPT ); Thu, 15 Jan 2009 22:01:12 -0500 Date: Fri, 16 Jan 2009 12:00:01 +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: Re: [PATCH 2/4] cgroup:add css_is_populated Message-Id: <20090116120001.f37e1895.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090115192712.33b533c3.kamezawa.hiroyu@jp.fujitsu.com> References: <20090115192120.9956911b.kamezawa.hiroyu@jp.fujitsu.com> <20090115192712.33b533c3.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: 2765 Lines: 81 Li-san, If you don't like this, could you give me an idea for "How to check cgroup is fully ready or not" ? BTW, why "we have a half filled direcotory - oh well" is allowed.... Thanks, -Kame On Thu, 15 Jan 2009 19:27:12 +0900 KAMEZAWA Hiroyuki wrote: > 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/ > -- 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/