Re: [Qemu-devel] [PATCH] hmp: fix regression of HMP device_del auto-completion

[Marcel Apfelbaum <marcel.a@redhat.com>]

On Wed, 2014-11-26 at 13:05 -0500, Luiz Capitulino wrote:
> On Wed, 26 Nov 2014 13:50:01 +0200
> Marcel Apfelbaum <marcel.a@redhat.com> wrote:
> 
> > 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).
> > 
> > Solved by observing that all devices appear as direct children of
> > /machine/peripheral container. No need of going recursively
> > over all the children.
> > 
> > Signed-off-by: Marcel Apfelbaum <marcel.a@redhat.com>
> 
> Peter, can you apply this patch directly to master to avoid me a pull
> request? Maybe it's a good idea to wait until tomorrow for more
> reviewers though.
Yes, another review would be welcomed, especially a QOM reviewer.
 
> 
> Marcel, thanks a lot for taking care of this!
No problem, glad to do it.

I forgot to add:
Reported-by: Gal Hammer <ghammer@redhat.com>

Thanks,
Marcel
> 
> > ---
> >  hw/core/qdev.c         | 12 ++++++++++--
> >  include/hw/qdev-core.h |  2 +-
> >  monitor.c              | 11 ++++-------
> >  3 files changed, 15 insertions(+), 10 deletions(-)
> > 
> > diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> > index 413b413..35fd00d 100644
> > --- a/hw/core/qdev.c
> > +++ b/hw/core/qdev.c
> > @@ -935,7 +935,7 @@ void qdev_alias_all_properties(DeviceState *target, Object *source)
> >      } while (class != object_class_by_name(TYPE_DEVICE));
> >  }
> >  
> > -int qdev_build_hotpluggable_device_list(Object *obj, void *opaque)
> > +static int qdev_add_hotpluggable_device(Object *obj, void *opaque)
> >  {
> >      GSList **list = opaque;
> >      DeviceState *dev = DEVICE(obj);
> > @@ -944,10 +944,18 @@ int qdev_build_hotpluggable_device_list(Object *obj, void *opaque)
> >          *list = g_slist_append(*list, dev);
> >      }
> >  
> > -    object_child_foreach(obj, qdev_build_hotpluggable_device_list, opaque);
> >      return 0;
> >  }
> >  
> > +GSList *qdev_build_hotpluggable_device_list(Object *peripheral)
> > +{
> > +    GSList *list = NULL;
> > +
> > +    object_child_foreach(peripheral, qdev_add_hotpluggable_device, &list);
> > +
> > +    return list;
> > +}
> > +
> >  static bool device_get_realized(Object *obj, Error **errp)
> >  {
> >      DeviceState *dev = DEVICE(obj);
> > diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> > index d3a2940..589bbe7 100644
> > --- a/include/hw/qdev-core.h
> > +++ b/include/hw/qdev-core.h
> > @@ -365,7 +365,7 @@ extern int qdev_hotplug;
> >  
> >  char *qdev_get_dev_path(DeviceState *dev);
> >  
> > -int qdev_build_hotpluggable_device_list(Object *obj, void *opaque);
> > +GSList *qdev_build_hotpluggable_device_list(Object *peripheral);
> >  
> >  void qbus_set_hotplug_handler(BusState *bus, DeviceState *handler,
> >                                Error **errp);
> > diff --git a/monitor.c b/monitor.c
> > index fa00594..f1031a1 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -4321,17 +4321,14 @@ void object_add_completion(ReadLineState *rs, int nb_args, const char *str)
> >  static void peripheral_device_del_completion(ReadLineState *rs,
> >                                               const char *str, size_t len)
> >  {
> > -    Object *peripheral;
> > -    GSList *list = NULL, *item;
> > +    Object *peripheral = container_get(qdev_get_machine(), "/peripheral");
> > +    GSList *list, *item;
> >  
> > -    peripheral = object_resolve_path("/machine/peripheral/", NULL);
> > -    if (peripheral == NULL) {
> > +    list = qdev_build_hotpluggable_device_list(peripheral);
> > +    if (!list) {
> >          return;
> >      }
> >  
> > -    object_child_foreach(peripheral, qdev_build_hotpluggable_device_list,
> > -                         &list);
> > -
> >      for (item = list; item; item = g_slist_next(item)) {
> >          DeviceState *dev = item->data;
> >  
>