From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755368AbaHYLfU (ORCPT ); Mon, 25 Aug 2014 07:35:20 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:46158 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752496AbaHYLfR (ORCPT ); Mon, 25 Aug 2014 07:35:17 -0400 X-IronPort-AV: E=Sophos;i="5.04,397,1406563200"; d="scan'208";a="35035870" Message-ID: <53FB1F36.8010307@cn.fujitsu.com> Date: Mon, 25 Aug 2014 19:34:14 +0800 From: Dongsheng Yang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: , CC: , , Dongsheng Yang Subject: Re: [PATCH] cgroup: Introduce cgroup_detach_task(). References: <1408966096-2209-1-git-send-email-yangds.fnst@cn.fujitsu.com> In-Reply-To: <1408966096-2209-1-git-send-email-yangds.fnst@cn.fujitsu.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.226.66] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry for the noise, :(. This patch is not a correct version. Please ignore it and I have sent a v2 for it. Thanx On 08/25/2014 07:28 PM, Dongsheng Yang wrote: > Currently, the only method to detach a task from a cgroup is moving > it to others. It looks not natrual to me. > > Inspired by cgroup_subtree_control_write(), this patch introduce allow > user to at-detach a process to/from a cgroup by echo "+/-pid" to > cgroup.procs. In addition, we keep the old method to allow user > echo "pid" without "+/-" to cgroup.procs as a attaching behavior. > > Signed-off-by: Dongsheng Yang > --- > kernel/cgroup.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 60 insertions(+), 2 deletions(-) > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index 7dc8788..11ef4ac 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -2348,6 +2348,43 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp, > return ret; > } > > +/** > + * cgroup_detach_task - detach a task or a whole threadgroup to a cgroup > + * @src_cgrp: the cgroup to detach from > + * @leader: the task or the leader of the threadgroup to be attached > + * @threadgroup: attach the whole threadgroup? > + * > + * Call holding cgroup_mutex and threadgroup_lock of @leader. > + */ > +static int cgroup_detach_task(struct cgroup *src_cgrp __maybe_unused, > + struct task_struct *leader, bool threadgroup) > +{ > + LIST_HEAD(preloaded_csets); > + struct task_struct *task; > + int ret; > + > + /* look up all src csets */ > + down_read(&css_set_rwsem); > + rcu_read_lock(); > + task = leader; > + do { > + cgroup_migrate_add_src(task_css_set(task), &cgrp_dfl_root.cgrp, > + &preloaded_csets); > + if (!threadgroup) > + break; > + } while_each_thread(leader, task); > + rcu_read_unlock(); > + up_read(&css_set_rwsem); > + > + /* prepare dst csets and commit */ > + ret = cgroup_migrate_prepare_dst(&cgrp_dfl_root.cgrp, &preloaded_csets); > + if (!ret) > + ret = cgroup_migrate(&cgrp_dfl_root.cgrp, leader, threadgroup); > + > + cgroup_migrate_finish(&preloaded_csets); > + return ret; > +} > + > /* > * Find the task_struct of the task to attach by vpid and pass it along to the > * function to attach either it or all tasks in its threadgroup. Will lock > @@ -2361,8 +2398,26 @@ static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, > struct cgroup *cgrp; > pid_t pid; > int ret; > + bool attach; > > - if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) > + /* > + * Parse input - space separated list of subsystem names prefixed > + * with either + or -. > + */ > + buf = strstrip(buf); > + if (*buf == '+') { > + attach = true; > + buf++; > + } else if (*buf == '-') { > + attach = false; > + buf++; > + } else { > + if (!isdigit(*buf)) > + return -EINVAL; > + attach = true; > + } > + > + if (kstrtoint(buf, 0, &pid) || pid < 0) > return -EINVAL; > > cgrp = cgroup_kn_lock_live(of->kn); > @@ -2426,7 +2481,10 @@ retry_find_task: > } > } > > - ret = cgroup_attach_task(cgrp, tsk, threadgroup); > + if (attach) > + ret = cgroup_attach_task(cgrp, tsk, threadgroup); > + else > + ret = cgroup_detach_task(cgrp, tsk, threadgroup); > > threadgroup_unlock(tsk); >