From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752460AbZHRX6n (ORCPT ); Tue, 18 Aug 2009 19:58:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752513AbZHRX6m (ORCPT ); Tue, 18 Aug 2009 19:58:42 -0400 Received: from smtp-out.google.com ([216.239.45.13]:10541 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752497AbZHRX6k (ORCPT ); Tue, 18 Aug 2009 19:58:40 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=from:subject:to:cc:date:message-id:in-reply-to:references: user-agent:mime-version:content-type: content-transfer-encoding:x-system-of-record; b=Chbh9tiHmcrEFFT2moBl6JZP4tp392uFGgcBxK3FGsDjEYgcdBDGinwrgKYQNbTUW 6HucpO1NcQ6o9J2S0t7kg== From: Paul Menage Subject: [PATCH 5/8] Changes css_set freeing mechanism to be under RCU To: akpm@linux-foundation.org, bblum@andrew.cmu.edu, lizf@cn.fujitsu.com Cc: linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org Date: Tue, 18 Aug 2009 16:58:32 -0700 Message-ID: <20090818235832.22531.96610.stgit@menage.mtv.corp.google.com> In-Reply-To: <20090818235059.22531.42618.stgit@menage.mtv.corp.google.com> References: <20090818235059.22531.42618.stgit@menage.mtv.corp.google.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ben Blum Changes css_set freeing mechanism to be under RCU This is a prepatch for making the procs file writable. In order to free the old css_sets for each task to be moved as they're being moved, the freeing mechanism must be RCU-protected, or else we would have to have a call to synchronize_rcu() for each task before freeing its old css_set. Signed-off-by: Ben Blum Signed-off-by: Paul Menage --- include/linux/cgroup.h | 3 +++ kernel/cgroup.c | 8 +++++++- 2 files changed, 10 insertions(+), 1 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 88e8634..3ac78a2 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -260,6 +260,9 @@ struct css_set { * during subsystem registration (at boot time). */ struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; + + /* For RCU-protected deletion */ + struct rcu_head rcu_head; }; /* diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 7e2b285..9f9e154 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -267,6 +267,12 @@ static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) return &css_set_table[index]; } +static void free_css_set_rcu(struct rcu_head *obj) +{ + struct css_set *cg = container_of(obj, struct css_set, rcu_head); + kfree(cg); +} + /* We don't maintain the lists running through each css_set to its * task until after the first call to cgroup_iter_start(). This * reduces the fork()/exit() overhead for people who have cgroups @@ -310,7 +316,7 @@ static void __put_css_set(struct css_set *cg, int taskexit) } write_unlock(&css_set_lock); - kfree(cg); + call_rcu(&cg->rcu_head, free_css_set_rcu); } /*