From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757541AbaC1CmH (ORCPT ); Thu, 27 Mar 2014 22:42:07 -0400 Received: from mail-qg0-f50.google.com ([209.85.192.50]:41753 "EHLO mail-qg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757514AbaC1Cl2 (ORCPT ); Thu, 27 Mar 2014 22:41:28 -0400 From: Tejun Heo To: lizefan@huawei.com Cc: containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 10/12] cgroup: update subsystem rebind restrictions Date: Thu, 27 Mar 2014 22:40:59 -0400 Message-Id: <1395974461-12735-11-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.8.5.3 In-Reply-To: <1395974461-12735-1-git-send-email-tj@kernel.org> References: <1395974461-12735-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Because the default root couldn't have any non-root csses attached to it, rebinding away from it was always allowed; however, the default hierarchy will soon host the unified hierarchy and have non-root csses so the rebind restrictions need to be updated accordingly. Instead of special casing rebinding from the default hierarchy and then checking whether the source hierarchy has children cgroups, which implies non-root csses for !dfl hierarchies, simply check whether the source hierarchy has non-root csses for the subsystem using css_next_child(). Signed-off-by: Tejun Heo --- kernel/cgroup.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index e714ccf..0c67141 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1051,16 +1051,12 @@ static int rebind_subsystems(struct cgroup_root *dst_root, if (!(ss_mask & (1 << ssid))) continue; - /* if @ss is on the dummy_root, we can always move it */ - if (ss->root == &cgrp_dfl_root) - continue; - - /* if @ss has non-root cgroups attached to it, can't move */ - if (!list_empty(&ss->root->cgrp.children)) + /* if @ss has non-root csses attached to it, can't move */ + if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss))) return -EBUSY; /* can't move between two non-dummy roots either */ - if (dst_root != &cgrp_dfl_root) + if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) return -EBUSY; } -- 1.8.5.3