From: Tejun Heo <tj@kernel.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: axboe@kernel.dk, ctalbott@google.com, rni@google.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/11] blkcg: let blkio_group point to blkio_cgroup directly
Date: Thu, 2 Feb 2012 12:33:52 -0800 [thread overview]
Message-ID: <20120202203352.GG19837@google.com> (raw)
In-Reply-To: <20120202200318.GB1723@redhat.com>
Hello,
On Thu, Feb 02, 2012 at 03:03:18PM -0500, Vivek Goyal wrote:
> > +static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
> > +{
> > + struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
> > +
> > if (blkcg != &blkio_root_cgroup)
> > kfree(blkcg);
>
> What makes sure that all the blkg are gone and they have dropped their
> reference to blkcg? IIUC, pre-destroy will just make sure to decouple
> blkg from request queue as well as blkcg list and also drop joint cgroup
> and request queue reference.
>
> But there could well be some IO queued in the group which might have
> its own reference and will be dropped later when IO completes. So at
> the time of blkiocg_destroy() it is not guranteed that there are
> no reference holders to blkcg?
Yeah, and that would wait till all css refs held by blkgs are gone,
right?
--
tejun
next prev parent reply other threads:[~2012-02-02 20:33 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-01 21:19 [PATCHSET] blkcg: unify blkgs for different policies Tejun Heo
2012-02-01 21:19 ` [PATCH 01/11] blkcg: let blkio_group point to blkio_cgroup directly Tejun Heo
2012-02-02 20:03 ` Vivek Goyal
2012-02-02 20:33 ` Tejun Heo [this message]
2012-02-02 20:55 ` Vivek Goyal
2012-02-01 21:19 ` [PATCH 02/11] block: relocate elevator initialized test from blk_cleanup_queue() to blk_drain_queue() Tejun Heo
2012-02-02 20:20 ` Vivek Goyal
2012-02-02 20:35 ` Tejun Heo
2012-02-02 20:37 ` Vivek Goyal
2012-02-02 20:38 ` Tejun Heo
2012-02-01 21:19 ` [PATCH 03/11] blkcg: add blkcg_{init|drain|exit}_queue() Tejun Heo
2012-02-01 21:19 ` [PATCH 04/11] blkcg: clear all request_queues on blkcg policy [un]registrations Tejun Heo
2012-02-01 21:19 ` [PATCH 05/11] blkcg: let blkcg core handle policy private data allocation Tejun Heo
2012-02-01 21:19 ` [PATCH 06/11] blkcg: move refcnt to blkcg core Tejun Heo
2012-02-02 22:07 ` Vivek Goyal
2012-02-02 22:11 ` Tejun Heo
2012-02-01 21:19 ` [PATCH 07/11] blkcg: make blkg->pd an array and move configuration and stats into it Tejun Heo
2012-02-01 21:19 ` [PATCH 08/11] blkcg: don't use blkg->plid in stat related functions Tejun Heo
2012-02-01 21:19 ` [PATCH 09/11] blkcg: move per-queue blkg list heads and counters to queue and blkg Tejun Heo
2012-02-02 22:47 ` Vivek Goyal
2012-02-02 22:47 ` Tejun Heo
2012-02-01 21:19 ` [PATCH 10/11] blkcg: let blkcg core manage per-queue blkg list and counter Tejun Heo
2012-02-01 21:19 ` [PATCH 11/11] blkcg: unify blkg's for blkcg policies Tejun Heo
2012-02-02 0:37 ` [PATCH UPDATED " Tejun Heo
2012-02-03 19:41 ` Vivek Goyal
2012-02-03 20:59 ` Tejun Heo
2012-02-03 21:44 ` Vivek Goyal
2012-02-03 21:47 ` Tejun Heo
2012-02-03 21:53 ` Vivek Goyal
2012-02-03 22:14 ` Tejun Heo
2012-02-03 22:23 ` Vivek Goyal
2012-02-03 22:28 ` Tejun Heo
2012-02-03 21:06 ` Vivek Goyal
2012-02-03 21:09 ` Tejun Heo
2012-02-03 21:10 ` Tejun Heo
2012-02-14 1:33 ` [PATCH UPDATED2 " Tejun Heo
2012-02-15 17:02 ` Vivek Goyal
2012-02-16 22:42 ` Tejun Heo
2012-02-02 19:29 ` [PATCHSET] blkcg: unify blkgs for different policies Vivek Goyal
2012-02-02 20:36 ` Tejun Heo
2012-02-02 20:43 ` Vivek Goyal
2012-02-02 20:59 ` Tejun Heo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120202203352.GG19837@google.com \
--to=tj@kernel.org \
--cc=axboe@kernel.dk \
--cc=ctalbott@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rni@google.com \
--cc=vgoyal@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.