From patchwork Wed Nov 7 17:15:08 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 1711771 Return-Path: X-Original-To: patchwork-linux-pm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id B88293FC8F for ; Wed, 7 Nov 2012 17:15:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752507Ab2KGRPP (ORCPT ); Wed, 7 Nov 2012 12:15:15 -0500 Received: from mail-pb0-f46.google.com ([209.85.160.46]:64837 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751346Ab2KGRPO (ORCPT ); Wed, 7 Nov 2012 12:15:14 -0500 Received: by mail-pb0-f46.google.com with SMTP id rr4so1350722pbb.19 for ; Wed, 07 Nov 2012 09:15:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=mVRp0a/12nacwouMlEViDqP4DovJyUIZ9acxhgoTxvU=; b=nvnimWhHp0dhdOd24gjaDz+YEf2qUy7Js2WEcrpE42nacLhjc800LZH412fTNV79MP Y4hgGdVVki6idmwFEukof2rWhJrN2ZcClO69XDWIDDCP9uO+ieDilL6p/JquJZeyjjU6 jrNtMzOXxwIwZxZuYu5dd6XaFWYS4YvOiUgPDms/XudcrIfzTfiuxQkCMt/bgKwVlgDz aMIEc/Si0PoBQPA/oUSqaya2W0DoT7QDd/+9WfLizfi8lYXXe/YqU9gvVWLfAdnhoc0u 10FKVv9mluPuW/K9n2nGSZ4kJW6mJNaN7GcxWVPDhSNAvhoeKBElxRyyL1NB35BFoJw1 759A== Received: by 10.68.204.132 with SMTP id ky4mr15369254pbc.164.1352308514026; Wed, 07 Nov 2012 09:15:14 -0800 (PST) Received: from mtj.dyndns.org (50-78-106-165-static.hfc.comcastbusiness.net. [50.78.106.165]) by mx.google.com with ESMTPS id hs1sm14408675pbc.33.2012.11.07.09.15.11 (version=SSLv3 cipher=OTHER); Wed, 07 Nov 2012 09:15:12 -0800 (PST) Date: Wed, 7 Nov 2012 09:15:08 -0800 From: Tejun Heo To: lizefan@huawei.com, mhocko@suse.cz, rjw@sisk.pl Cc: containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, fweisbec@gmail.com, Glauber Costa Subject: [PATCH 1/9 v2] cgroup: add cgroup_subsys->post_create() Message-ID: <20121107171508.GF2660@mtj.dyndns.org> References: <1351931915-1701-1-git-send-email-tj@kernel.org> <1351931915-1701-2-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1351931915-1701-2-git-send-email-tj@kernel.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Currently, there's no way for a controller to find out whether a new cgroup finished all ->create() allocatinos successfully and is considered "live" by cgroup. This becomes a problem later when we add generic descendants walking to cgroup which can be used by controllers as controllers don't have a synchronization point where it can synchronize against new cgroups appearing in such walks. This patch adds ->post_create(). It's called after all ->create() succeeded and the cgroup is linked into the generic cgroup hierarchy. This plays the counterpart of ->pre_destroy(). When used in combination with the to-be-added generic descendant iterators, ->post_create() can be used to implement reliable state inheritance. It will be explained with the descendant iterators. v2: Added a paragraph about its future use w/ descendant iterators per Michal. Signed-off-by: Tejun Heo Acked-by: Michal Hocko Cc: Glauber Costa Reviewed-by: KAMEZAWA Hiroyuki --- If you can explain it better, please be my guest. Thanks. include/linux/cgroup.h | 1 + kernel/cgroup.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -438,6 +438,7 @@ int cgroup_taskset_size(struct cgroup_ta struct cgroup_subsys { struct cgroup_subsys_state *(*create)(struct cgroup *cgrp); + void (*post_create)(struct cgroup *cgrp); void (*pre_destroy)(struct cgroup *cgrp); void (*destroy)(struct cgroup *cgrp); int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset); --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4060,10 +4060,15 @@ static long cgroup_create(struct cgroup if (err < 0) goto err_remove; - /* each css holds a ref to the cgroup's dentry */ - for_each_subsys(root, ss) + for_each_subsys(root, ss) { + /* each css holds a ref to the cgroup's dentry */ dget(dentry); + /* creation succeeded, notify subsystems */ + if (ss->post_create) + ss->post_create(cgrp); + } + /* The cgroup directory was pre-locked for us */ BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex)); @@ -4281,6 +4286,9 @@ static void __init cgroup_init_subsys(st ss->active = 1; + if (ss->post_create) + ss->post_create(&ss->root->top_cgroup); + /* this function shouldn't be used with modular subsystems, since they * need to register a subsys_id, among other things */ BUG_ON(ss->module);