linux-kernel - Re: [PATCH 2/6] cgroup: improve old cgroup handling in cgroup_attach

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 25 Aug 2011 01:51:39 -0700
From:	Paul Menage <paul@...lmenage.org>
To:	Tejun Heo <tj@...nel.org>
Cc:	rjw@...k.pl, lizf@...fujitsu.com,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org
Subject: Re: [PATCH 2/6] cgroup: improve old cgroup handling in cgroup_attach_proc()

On Tue, Aug 23, 2011 at 3:19 PM, Tejun Heo <tj@...nel.org> wrote:
> cgroup_attach_proc() behaves differently from cgroup_attach_task() in
> the following aspects.
>
> * All hooks are invoked even if no task is actually being moved.
>
> * ->can_attach_task() is called for all tasks in the group whether the
>  new cgrp is different from the current cgrp or not; however,
>  ->attach_task() is skipped if new equals new.  This makes the calls
>  asymmetric.
>
> This patch improves old cgroup handling in cgroup_attach_proc() by
> looking up the current cgroup at the head, recording it in the flex
> array along with the task itself, and using it to remove the above two
> differences.  This will also ease further changes.

While I'm all in favour of making things more consistent, do we need
such a big change?

In particular, making the group flex-array entries contain both a task
and a cgroup appears to be only necessary in order to skip tasks where
new_cgroup == old_cgroup. Can't we get the same effect by simply
leaving all such tasks out of the flex-array in the first place?

Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/