Re: [Qemu-devel] "object_delete: assertion failed: (obj->ref == 0)" deleting usb-storage from monitor

[Peter Maydell]

On 4 July 2012 14:51, Peter Maydell <address@hidden> wrote:
> On 2 July 2012 18:28, Peter Maydell <address@hidden> wrote:
>> If you create a usb-storage device on the qemu command line
>> and then try to delete it via the monitor, QEMU asserts:
>>
>> $ dd if=/dev/zero bs=4096 count=1024 of=usb.img
>> $ ./i386-softmmu/qemu-system-i386 -clock unix -monitor stdio -usb
>> -drive if=none,file=usb.img,id=myusb  -device
>> usb-storage,id=myusb,drive=myusb,removable=on
>> QEMU 1.1.50 monitor - type 'help' for more information
>> (qemu) device_del myusb
>> **
>> ERROR:qom/object.c:408:object_delete: assertion failed: (obj->ref == 0)
>> Aborted
>
> Further investigation shows that this is happening because
> device_finalize (at #19 in this backtrace) tries to free the
> 'usb-storage' device; it handles child buses (which in this
> case is the SCSI bus the usb-storage module's disk is hanging
> off) by (via qbus_finalize()) freeing all the devices on the
> bus. Unfortunately the "scsi-disk" object still has a nonzero
> refcount, and so we assert.
>
> The stray reference to the object is coming from qdev_init():
>         object_property_add_child(container_get(qdev_get_machine(),
>                                                 "/unattached"),
>                                   name, OBJECT(dev), NULL);
>
> ...what should be unreffing this reference when the qdev object
> is deleted?

Just a note that this assert() still happens in current
git master...

-- PMM