[Qemu-devel] [Regression] hmp: QEMU crash on device_del auto-completion

[Qemu-devel] [Regression] hmp: QEMU crash on device_del auto-completion

[Marcel Apfelbaum]

Hi,

The commits:
 - 6a1fa9f5 (monitor: add del completion for peripheral device) 
 - 66e56b13 (qdev: add qdev_build_hotpluggable_device_list helper)

cause a QEMU crash when trying to use HMP device_del auto-completion.
It can be easily reproduced by:
<qemu-bin> -enable-kvm  ~/images/fedora.qcow2 -monitor stdio -device virtio-net-pci,id=vnet
(qemu) device_del /home/mapfelba/git/upstream/qemu/hw/core/qdev.c:941:qdev_build_hotpluggable_device_list: Object 0x7f6ce04e4fe0 is not an instance of type device
Aborted (core dumped)

The root cause is qdev_build_hotpluggable_device_list going recursively over
all peripherals and their children assuming all are devices. It doesn't work
since PCI devices have at least on child which is a memory region (bus master).

Should we try to fix it for 2.2 or simply revert it?
Thanks,
  Marcel

Re: [Qemu-devel] [Regression] hmp: QEMU crash on device_del auto-completion

[Luiz Capitulino]

On Tue, 25 Nov 2014 16:04:19 +0200
Marcel Apfelbaum <marcel.a@redhat.com> wrote:

> Hi,
> 
> The commits:
>  - 6a1fa9f5 (monitor: add del completion for peripheral device) 
>  - 66e56b13 (qdev: add qdev_build_hotpluggable_device_list helper)
> 
> cause a QEMU crash when trying to use HMP device_del auto-completion.
> It can be easily reproduced by:
> <qemu-bin> -enable-kvm  ~/images/fedora.qcow2 -monitor stdio -device virtio-net-pci,id=vnet
> (qemu) device_del /home/mapfelba/git/upstream/qemu/hw/core/qdev.c:941:qdev_build_hotpluggable_device_list: Object 0x7f6ce04e4fe0 is not an instance of type device
> Aborted (core dumped)
> 
> The root cause is qdev_build_hotpluggable_device_list going recursively over
> all peripherals and their children assuming all are devices. It doesn't work
> since PCI devices have at least on child which is a memory region (bus master).
> 
> Should we try to fix it for 2.2 or simply revert it?

Do you think you can post a patch in the next few days? If you can then
let's try to fix it, otherwise we better revert those commits.

Re: [Qemu-devel] [Regression] hmp: QEMU crash on device_del auto-completion

[Marcel Apfelbaum]

On Tue, 2014-11-25 at 09:12 -0500, Luiz Capitulino wrote:
> On Tue, 25 Nov 2014 16:04:19 +0200
> Marcel Apfelbaum <marcel.a@redhat.com> wrote:
> 
> > Hi,
> > 
> > The commits:
> >  - 6a1fa9f5 (monitor: add del completion for peripheral device) 
> >  - 66e56b13 (qdev: add qdev_build_hotpluggable_device_list helper)
> > 
> > cause a QEMU crash when trying to use HMP device_del auto-completion.
> > It can be easily reproduced by:
> > <qemu-bin> -enable-kvm  ~/images/fedora.qcow2 -monitor stdio -device virtio-net-pci,id=vnet
> > (qemu) device_del /home/mapfelba/git/upstream/qemu/hw/core/qdev.c:941:qdev_build_hotpluggable_device_list: Object 0x7f6ce04e4fe0 is not an instance of type device
> > Aborted (core dumped)
> > 
> > The root cause is qdev_build_hotpluggable_device_list going recursively over
> > all peripherals and their children assuming all are devices. It doesn't work
> > since PCI devices have at least on child which is a memory region (bus master).
> > 
> > Should we try to fix it for 2.2 or simply revert it?
> 
> Do you think you can post a patch in the next few days? If you can then
> let's try to fix it, otherwise we better revert those commits.

I'll try, sure.
Thanks,
Marcel

Re: [Qemu-devel] [Regression] hmp: QEMU crash on device_del auto-completion

[Zhu Guihua]

On Tue, 2014-11-25 at 16:23 +0200, Marcel Apfelbaum wrote:
> On Tue, 2014-11-25 at 09:12 -0500, Luiz Capitulino wrote:
> > On Tue, 25 Nov 2014 16:04:19 +0200
> > Marcel Apfelbaum <marcel.a@redhat.com> wrote:
> > 
> > > Hi,
> > > 
> > > The commits:
> > >  - 6a1fa9f5 (monitor: add del completion for peripheral device) 
> > >  - 66e56b13 (qdev: add qdev_build_hotpluggable_device_list helper)
> > > 
> > > cause a QEMU crash when trying to use HMP device_del auto-completion.
> > > It can be easily reproduced by:
> > > <qemu-bin> -enable-kvm  ~/images/fedora.qcow2 -monitor stdio -device virtio-net-pci,id=vnet
> > > (qemu) device_del /home/mapfelba/git/upstream/qemu/hw/core/qdev.c:941:qdev_build_hotpluggable_device_list: Object 0x7f6ce04e4fe0 is not an instance of type device
> > > Aborted (core dumped)
> > > 
> > > The root cause is qdev_build_hotpluggable_device_list going recursively over
> > > all peripherals and their children assuming all are devices. It doesn't work
> > > since PCI devices have at least on child which is a memory region (bus master).
> > > 
> > > Should we try to fix it for 2.2 or simply revert it?
> > 
> > Do you think you can post a patch in the next few days? If you can then
> > let's try to fix it, otherwise we better revert those commits.
> 
> I'll try, sure.

I'm sorry that my patch causes this bug.
Thanks for your work to fix this.

Regards,
Zhu

> Thanks,
> Marcel
>