public inbox for netdev@vger.kernel.org 
 help / color / mirror / Atom feed

From: Li Zefan <lizf@cn•fujitsu.com>
To: Paul Menage <menage@google•com>
Cc: Grzegorz Nosek <root@localdomain•pl>,
	containers@lists•osdl.org, netdev@vger•kernel.org
Subject: Re: [Devel] Re: [RFC][PATCH] IP address restricting cgroup subsystem
Date: Mon, 12 Jan 2009 10:20:16 +0800	[thread overview]
Message-ID: <496AA8E0.2070002@cn.fujitsu.com> (raw)
In-Reply-To: <6599ad830901100814g5faeb611v7a36eed987c103ff@mail.gmail.com>

Paul Menage wrote:
> On Fri, Jan 9, 2009 at 8:50 PM, Li Zefan <lizf@cn•fujitsu.com> wrote:
>>> For checking the "children" list, you can just lock
>>> ipaddr_subsys.hierarchy_mutex.
>>>
>> Unfortunately hierarchy_mutex can't be used here, since hierarchy_mutex
>> doesn't protect subsys's create() method, and the create() will access
>> parent cgroup's data.
>>
> 
> But that can be solved by putting a spinlock in the ipaddr_cgroup
> structure and taking it in the write handler (and the connect/bind
> handlers, which should also be using RCU), and taking the parent
> structure's lock before copying from it in the create callback. No
> need for something as heavy as cgroup_lock().
> 

Still won't work. :(

================
lock(ipaddr_subsys.hierarchy_mutex);

if (list_empty(&cgrp->children) &&
    parent->ipv4_addr == INADDR_ANY)
						create()
						  parent->spin_lock();
						  cgrp->ipv4_addr = parent->ipv4_addr;
						  parent->spin_unlock();
	ipcgroup->spin_lock();
	ipcgroup->ipv4_addr = new_addr;
	ipcgroup->spin_unlock();

unlock(ipaddr_subsys.hierarchy_mutex);
						list_add(&cgrp->sibling, &cgrp->parent->children);
================

And neither can it work to hold hierarchy_mutex in subsys's create().

I think the only way to make hierarchy_mutex works for this issue is:

@@ -2403,16 +2403,18 @@ static long cgroup_create(struct cgroup *parent, struct
        if (notify_on_release(parent))
                set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);

+       cgroup_lock_hierarchy(root);
+
        for_each_subsys(root, ss) {
                struct cgroup_subsys_state *css = ss->create(ss, cgrp);
                if (IS_ERR(css)) {
+                       cgroup_unlock_hierarchy(root);
                        err = PTR_ERR(css);
                        goto err_destroy;
                }
                init_cgroup_css(css, ss, cgrp);
        }

-       cgroup_lock_hierarchy(root);
        list_add(&cgrp->sibling, &cgrp->parent->children);
        cgroup_unlock_hierarchy(root);
        root->number_of_cgroups++;

next prev parent reply	other threads:[~2009-01-12  2:21 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20090106230554.GB25228@eskarina.localdomain.pl>
     [not found] ` <20090106230554.GB25228-IaEwMO9oKu/77SC2UrCW1JJg/dWx8T/9@public.gmane.org>
2009-01-07  6:01   ` [RFC][PATCH] IP address restricting cgroup subsystem Li Zefan
     [not found]     ` <49644526.8030205-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2009-01-07  7:38       ` Grzegorz Nosek
2009-01-07  8:36         ` Li Zefan
2009-01-07  9:16           ` Grzegorz Nosek
2009-01-07  9:33             ` Li Zefan
2009-01-07  9:37               ` Grzegorz Nosek
2009-01-09 21:38               ` [Devel] " Paul Menage
2009-01-10  4:50                 ` Li Zefan
2009-01-10 16:14                   ` Paul Menage
2009-01-12  2:20                     ` Li Zefan [this message]
2009-01-14  2:07                       ` Paul Menage
2009-01-14  2:47                         ` Li Zefan
2009-01-14  2:50                           ` Paul Menage

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=496AA8E0.2070002@cn.fujitsu.com \
    --to=lizf@cn$(echo .)fujitsu.com \
    --cc=containers@lists$(echo .)osdl.org \
    --cc=menage@google$(echo .)com \
    --cc=netdev@vger$(echo .)kernel.org \
    --cc=root@localdomain$(echo .)pl \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox