From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932261AbaEIVQK (ORCPT ); Fri, 9 May 2014 17:16:10 -0400 Received: from mail-qg0-f42.google.com ([209.85.192.42]:61151 "EHLO mail-qg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757664AbaEIVNp (ORCPT ); Fri, 9 May 2014 17:13:45 -0400 From: Tejun Heo To: lizefan@huawei.com Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 4/9] cgroup: move check_for_release(parent) call to the end of cgroup_destroy_locked() Date: Fri, 9 May 2014 17:13:30 -0400 Message-Id: <1399670015-23463-5-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1399670015-23463-1-git-send-email-tj@kernel.org> References: <1399670015-23463-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, check_for_release() on the parent of a destroyed cgroup is invoked from cgroup_destroy_css_killed(). This is because this is where the destroyed cgroup can be removed from the parent's children list. check_for_release() tests the emptiness of the list directly, so invoking it before removing the cgroup from the list makes it think that the parent still has children even when it no longer does. This patch updates check_for_release() to use cgroup_has_live_children() instead of directly testing ->children emptiness and moves check_for_release(parent) earlier to the end of cgroup_destroy_locked(). As cgroup_has_live_children() ignores cgroups marked DEAD, check_for_release() functions correctly as long as it's called after asserting DEAD. This makes release notification slightly more timely and more importantly enables further simplification of cgroup destruction path. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index d369f19..45149b7 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4541,6 +4541,9 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) */ kernfs_remove(cgrp->kn); + set_bit(CGRP_RELEASABLE, &cgrp->parent->flags); + check_for_release(cgrp->parent); + return 0; }; @@ -4555,17 +4558,12 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) */ static void cgroup_destroy_css_killed(struct cgroup *cgrp) { - struct cgroup *parent = cgrp->parent; - lockdep_assert_held(&cgroup_mutex); /* delete this cgroup from parent->children */ list_del_rcu(&cgrp->sibling); cgroup_put(cgrp); - - set_bit(CGRP_RELEASABLE, &parent->flags); - check_for_release(parent); } static int cgroup_rmdir(struct kernfs_node *kn) @@ -5005,7 +5003,7 @@ void cgroup_exit(struct task_struct *tsk) static void check_for_release(struct cgroup *cgrp) { if (cgroup_is_releasable(cgrp) && - list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) { + list_empty(&cgrp->cset_links) && !cgroup_has_live_children(cgrp)) { /* * Control Group is currently removeable. If it's not * already queued for a userspace notification, queue -- 1.9.0