Re: [Qemu-devel] weird qdev error

[Anthony Liguori <anthony@codemonkey.ws>]

On 02/12/2012 02:15 PM, Michael S. Tsirkin wrote:
> On Sun, Feb 12, 2012 at 02:04:29PM -0600, Anthony Liguori wrote:
>> 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.
>
> Th other problem was internal in pci which calls ->hostplug
> during initialization. This doesn't seem affected?
> But I didn't try, maybe I misundertand.

Yeah, from qdev's perspective it's all just init failing.  hotplug is entirely a 
PCI concept.

>
>> 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
>
> Me too. Want to try to drop them?

Yeah, I'll make this a two patch series.

Regards,

Anthony Liguori

>