This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
Home Products Support Community News


Re: [Xen-devel] "kobject add failed"

To: "Petersson, Mats" <Mats.Petersson@xxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] "kobject add failed"
From: Keir Fraser <keir@xxxxxxxxxxxxx>
Date: Thu, 03 May 2007 18:26:41 +0100
Delivery-date: Thu, 03 May 2007 10:31:21 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <907625E08839C4409CE5768403633E0B018E1CC4@xxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AceNmT0esnMamshHQgCftANOeSweVQACJPy4AAAGsIAAAMJU7AAAcFqwAABf97A=
Thread-topic: [Xen-devel] "kobject add failed"
User-agent: Microsoft-Entourage/

On 3/5/07 18:19, "Petersson, Mats" <Mats.Petersson@xxxxxxx> wrote:

>> However, the invocation of tun_set_iff() is wrapped in
>> rtnl_lock()/unlock()
>> so should be concurrency safe. Still, this is where I would
>> concentrate my
>> search if I were you.
> Indeed, the tun_set_iff() is protected by rtnl_lock/unlock()... Any
> reason to believe that doesn't work?

Your crash report. :-)

However tun_set_iff() is not in the oops backtrace... Perhaps I'm wrong
about which ioctl is being executed, or the path taken through the Linux

However, it definitely does look like a lack of locking around picking a
device name and registering it. I'm fairly confident that this will turn out
to be the problem. You might want to add some tracing to the kernel to find
out what paths you take during qemu-dm startup (this might cause the race
not to happen any more, but you can remove the tracing once you know which
functions you should be staring at).

 -- Keir

Xen-devel mailing list