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From: Frederic Weisbecker <fweisbec@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Paul Menage <paul@paulmenage.org>, Li Zefan <lizf@cn.fujitsu.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Aditya Kali <adityakali@google.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Kay Sievers <kay.sievers@vrfy.org>,
	Tim Hockin <thockin@hockin.org>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 06/12] cgroups: Add res counter common ancestor searching
Date: Fri, 9 Sep 2011 14:31:29 +0200	[thread overview]
Message-ID: <20110909123123.GA14072@somewhere.redhat.com> (raw)
In-Reply-To: <20110906152129.c6136981.akpm@linux-foundation.org>

On Tue, Sep 06, 2011 at 03:21:29PM -0700, Andrew Morton wrote:
> On Tue,  6 Sep 2011 02:13:00 +0200
> Frederic Weisbecker <fweisbec@gmail.com> wrote:
> 
> > +struct res_counter *
> > +res_counter_common_ancestor(struct res_counter *r1, struct res_counter *r2)
> > +{
> > +	struct res_counter *iter;
> > +
> > +	while (r1) {
> > +		iter = r2;
> > +		while (iter) {
> > +			if (iter == r1)
> > +				return iter;
> > +			iter = iter->parent;
> > +		}
> > +
> > +		r1 = r1->parent;
> > +	}
> > +
> > +	return NULL;
> > +}
> 
> cgroup_mutex, one assumes?

No, a cgroup can't move to other parents, they remain stable
as long as they have children (if I understood correctly).
So this mirrors to res_counters.

In fact res counters is just a library, pretty much like
lists, except they are only used by cgroups for now, so it's up
to the caller to guarantee the stability of its objects.

But yeah the documentation for this function is missing. I'm
adding some comments in the file.

  reply	other threads:[~2011-09-09 12:31 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-06  0:12 [PATCH 00/12 v4][RESEND] cgroups: Task counter subsystem Frederic Weisbecker
2011-09-06  0:12 ` [PATCH 01/12] cgroups: Add res_counter_write_u64() API Frederic Weisbecker
2011-09-06  0:12 ` [PATCH 02/12] cgroups: New resource counter inheritance API Frederic Weisbecker
2011-09-06 22:17   ` Andrew Morton
2011-09-08 13:25     ` Frederic Weisbecker
2011-09-06  0:12 ` [PATCH 03/12] cgroups: Add previous cgroup in can_attach_task/attach_task callbacks Frederic Weisbecker
2011-09-06  0:12 ` [PATCH 04/12] cgroups: New cancel_attach_task subsystem callback Frederic Weisbecker
2011-09-06  0:12 ` [PATCH 05/12] cgroups: Ability to stop res charge propagation on bounded ancestor Frederic Weisbecker
2011-09-06  0:13 ` [PATCH 06/12] cgroups: Add res counter common ancestor searching Frederic Weisbecker
2011-09-06 22:21   ` Andrew Morton
2011-09-09 12:31     ` Frederic Weisbecker [this message]
2011-09-06  0:13 ` [PATCH 07/12] res_counter: Allow charge failure pointer to be null Frederic Weisbecker
2011-09-06  0:13 ` [PATCH 08/12] cgroups: Pull up res counter charge failure interpretation to caller Frederic Weisbecker
2011-09-06 22:26   ` Andrew Morton
2011-09-09 13:33     ` Frederic Weisbecker
2011-09-09 15:17       ` Andrew Morton
2011-09-06  0:13 ` [PATCH 09/12] cgroups: Add a task counter subsystem Frederic Weisbecker
2011-09-06 22:40   ` Andrew Morton
2011-09-13 15:13     ` Frederic Weisbecker
2011-09-06  0:13 ` [PATCH 10/12] cgroups: Add documentation for " Frederic Weisbecker
2011-09-06 22:41   ` Andrew Morton
2011-09-13 17:35     ` Frederic Weisbecker
2011-09-06  0:13 ` [RFC PATCH 11/12] cgroups: Allow subsystems to cancel a fork Frederic Weisbecker
2011-09-15 21:09   ` Andrew Morton
2011-10-01 15:29     ` Frederic Weisbecker
2011-09-06  0:13 ` [RFC PATCH 12/12] cgroups: Convert task counter to use the subsys fork callback Frederic Weisbecker

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