Re: [Qemu-devel] weird qdev error

[Anthony Liguori <anthony@codemonkey.ws>]

On 02/12/2012 11:57 AM, Michael S. Tsirkin wrote:
> On Sun, Feb 12, 2012 at 11:38:24AM -0600, Anthony Liguori wrote:
>> From: Anthony Liguori<aliguori@us.ibm.com>
>> Date: Sun, 12 Feb 2012 11:36:24 -0600
>> Subject: [PATCH] device_add: don't add a /peripheral link until init is complete
>>
>> Otherwise we end up with a dangling reference which causes qdev_free() to fail.
>>
>> Reported-by: Michael Tsirkin<mst@redhat.com>
>> Signed-off-by: Anthony Liguori<aliguori@us.ibm.com>
>
> This handles the option parsing but what about hotplug
> failures (when bus->hotplug returns an error)?

Sorry, I don't follow.

The assert you reported was that object_free() noted a reference count of !0 
which indicates something else was holding the reference to the object.  In this 
case, it was the child link in /peripheral.

By delaying creating the link in /peripheral, we eliminate the problem completely.

BTW, the explicit calls to do_pci_unregister are redundant.  finalize() will be 
called during cleanup which means exit() will be invoked (which already calls 
do_pci_unregister).  I'm not sure why this isn't failing more aggressively but 
it looks clearly wrong to me.

Regards,

Anthony Liguori