From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753889AbcAGWbZ (ORCPT ); Thu, 7 Jan 2016 17:31:25 -0500 Received: from mail-yk0-f182.google.com ([209.85.160.182]:34663 "EHLO mail-yk0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753460AbcAGWaD (ORCPT ); Thu, 7 Jan 2016 17:30:03 -0500 From: Tejun Heo To: lizefan@huawei.com, hannes@cmpxchg.org, a.p.zijlstra@chello.nl, mingo@redhat.com, acme@kernel.org Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, kernel-team@fb.com, Tejun Heo Subject: [PATCH 4/6] cgroup: use ->subtree_control when testing no internal process rule Date: Thu, 7 Jan 2016 17:29:48 -0500 Message-Id: <1452205790-21331-5-git-send-email-tj@kernel.org> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1452205790-21331-1-git-send-email-tj@kernel.org> References: <1452205790-21331-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org No internal process rule is enforced by cgroup_migrate_prepare_dst() during process migration. It tests whether the target cgroup's ->child_subsys_mask is zero which is different from "subtree_control" write path which tests ->subtree_control. This hasn't mattered because up until now, both ->child_subsys_mask and ->subtree_control are zero or non-zero at the same time. However, with the planned addition of implicit controllers, this will no longer be true. This patch prepares for the change by making cgorup_migrate_prepare_dst() test ->subtree_control instead. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 8a92043..8bc83fd 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2512,11 +2512,11 @@ static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, lockdep_assert_held(&cgroup_mutex); /* - * Except for the root, child_subsys_mask must be zero for a cgroup + * Except for the root, subtree_control must be zero for a cgroup * with tasks so that child cgroups don't compete against tasks. */ if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) && - dst_cgrp->child_subsys_mask) + dst_cgrp->subtree_control) return -EBUSY; /* look up the dst cset for each src cset and link it to src */ -- 2.5.0