From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zefan Subject: Re: [PATCH 1/5 V3] cgroup: remove redundate get/put of old css_set from migrate Date: Wed, 21 Dec 2011 09:10:45 +0800 Message-ID: <4EF13215.905@cn.fujitsu.com> References: <1324422873-31001-1-git-send-email-msb@chromium.org> <1324422873-31001-2-git-send-email-msb@chromium.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1324422873-31001-2-git-send-email-msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Mandeep Singh Baines Cc: Tejun Heo , LKML , Frederic Weisbecker , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, KAMEZAWA Hiroyuki , Oleg Nesterov , Andrew Morton , Paul Menage Mandeep Singh Baines wrote: > Changes in V3: > * Fixed to put error in retval (thanks Frederic Weisbecker) > * https://lkml.org/lkml/2011/12/20/255 > Changes in V2: > * Updated commit message as per Tejun's feedback: > * https://lkml.org/lkml/2011/12/19/289 > > -- >8 -- (snip) > > We can now assume that the css_set reference held by the task > will not go away for an exiting task. PF_EXITING state can be > trusted throughout migration by checking it after locking > threadgroup. > > While at it, renamed css_set_check_fetched to css_set_fetched. > !css_set_fetched() seems to read better than > !css_set_check_fetched(). > > Signed-off-by: Mandeep Singh Baines > Cc: Tejun Heo > Cc: Li Zefan > Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org > Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > Cc: KAMEZAWA Hiroyuki > Cc: Frederic Weisbecker > Cc: Oleg Nesterov > Cc: Andrew Morton > Cc: Paul Menage > --- > kernel/cgroup.c | 25 ++++++------------------- > 1 files changed, 6 insertions(+), 19 deletions(-) > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index bc3caff..4166066 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -1856,7 +1856,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, > */ > task_lock(tsk); The comments above this line of code should be updated accordingly. > oldcg = tsk->cgroups; > - get_css_set(oldcg); > task_unlock(tsk); > > /* locate or allocate a new css_set for this task. */ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753995Ab1LUBIi (ORCPT ); Tue, 20 Dec 2011 20:08:38 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:59452 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753978Ab1LUBIh (ORCPT ); Tue, 20 Dec 2011 20:08:37 -0500 Message-ID: <4EF13215.905@cn.fujitsu.com> Date: Wed, 21 Dec 2011 09:10:45 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc14 Thunderbird/3.1.4 MIME-Version: 1.0 To: Mandeep Singh Baines CC: Tejun Heo , LKML , Frederic Weisbecker , containers@lists.linux-foundation.org, cgroups@vger.kernel.org, KAMEZAWA Hiroyuki , Oleg Nesterov , Andrew Morton , Paul Menage Subject: Re: [PATCH 1/5 V3] cgroup: remove redundate get/put of old css_set from migrate References: <1324422873-31001-1-git-send-email-msb@chromium.org> <1324422873-31001-2-git-send-email-msb@chromium.org> In-Reply-To: <1324422873-31001-2-git-send-email-msb@chromium.org> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-12-21 09:07:53, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-12-21 09:07:54, Serialize complete at 2011-12-21 09:07:54 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mandeep Singh Baines wrote: > Changes in V3: > * Fixed to put error in retval (thanks Frederic Weisbecker) > * https://lkml.org/lkml/2011/12/20/255 > Changes in V2: > * Updated commit message as per Tejun's feedback: > * https://lkml.org/lkml/2011/12/19/289 > > -- >8 -- (snip) > > We can now assume that the css_set reference held by the task > will not go away for an exiting task. PF_EXITING state can be > trusted throughout migration by checking it after locking > threadgroup. > > While at it, renamed css_set_check_fetched to css_set_fetched. > !css_set_fetched() seems to read better than > !css_set_check_fetched(). > > Signed-off-by: Mandeep Singh Baines > Cc: Tejun Heo > Cc: Li Zefan > Cc: containers@lists.linux-foundation.org > Cc: cgroups@vger.kernel.org > Cc: KAMEZAWA Hiroyuki > Cc: Frederic Weisbecker > Cc: Oleg Nesterov > Cc: Andrew Morton > Cc: Paul Menage > --- > kernel/cgroup.c | 25 ++++++------------------- > 1 files changed, 6 insertions(+), 19 deletions(-) > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index bc3caff..4166066 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -1856,7 +1856,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, > */ > task_lock(tsk); The comments above this line of code should be updated accordingly. > oldcg = tsk->cgroups; > - get_css_set(oldcg); > task_unlock(tsk); > > /* locate or allocate a new css_set for this task. */