Re: [Qemu-devel] [PATCH v4] qdev: DEVICE_DELETED event

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Mar 08, 2013 at 07:36:28AM -0600, Anthony Liguori wrote:
> Markus Armbruster <armbru@redhat.com> writes:
> 
> > "Michael S. Tsirkin" <mst@redhat.com> writes:
> >
> >> On Thu, Mar 07, 2013 at 08:57:52PM +0100, Markus Armbruster wrote:
> >>> "Michael S. Tsirkin" <mst@redhat.com> writes:
> >>> 
> >>> > libvirt has a long-standing bug: when removing the device,
> >>> > it can request removal but does not know when the
> >>> > removal completes. Add an event so we can fix this in a robust way.
> >>> >
> >>> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> >>> 
> >>> Speaking as the acting QMP maintainer, just to avoid misunderstandings:
> >>> there's disagreement on the event's design, namely when it should fire,
> >>> and how it should name the device.  I don't want the discussion
> >>> preempted by a commit.
> >>
> >> Yes, you are asking for more functionality, but can I add this in a
> >> follow-up commit please?  I prefer this patch as is, as it can be
> >> backported to stable branches and downstreams.  Upstream a follow up
> >> patch can add fields and more triggers which won't apply to any
> >> downstreams.
> >
> > If you want to address my review comments in a separate patch, go right
> > ahead.  Please post both together as a series, for coherent review and
> > to simplify patch tracking.
> >
> > I'm asking for two things:
> >
> > 1. Event member path.  Fair to call this "more functionality".  I agree
> >    that backporting it to pre-QOM versions isn't practical.
> >
> > 2. Sane event trigger condition: on any device deletion, not just when
> >    the device happens to have a qdev ID.  This isn't "more", it's
> >    "different".
> 
> Ack.
> 
> Regards,
> 
> Anthony Liguori


So how does one get the path that you require?

ERROR:qom/object.c:1011:object_get_canonical_path: assertion failed: (prop != NULL)

Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7fffeffff700 (LWP 29475)]
0x00007ffff587d8a5 in raise () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install SDL-1.2.14-2.el6.x86_64 glib2-2.22.5-6.el6.x86_64 glibc-2.12-1.80.el6_3.3.x86_64 libX11-1.3-2.el6.x86_64 libXau-1.0.5-1.el6.x86_64 libpng-1.2.48-1.el6_2.x86_64 libxcb-1.5-1.el6.x86_64 ncurses-libs-5.7-3.20090208.el6.x86_64 pixman-0.18.4-1.el6_0.1.x86_64 zlib-1.2.3-27.el6.x86_64
(gdb) where
#0  0x00007ffff587d8a5 in raise () from /lib64/libc.so.6
#1  0x00007ffff587f085 in abort () from /lib64/libc.so.6
#2  0x00007ffff737ca7f in g_assertion_message () from /lib64/libglib-2.0.so.0
#3  0x00007ffff737d020 in g_assertion_message_expr () from /lib64/libglib-2.0.so.0
#4  0x00007ffff7deef76 in object_get_canonical_path (obj=0x7ffff8f1a010) at qom/object.c:1011
#5  0x00007ffff7d7abcd in device_unparent (obj=0x7ffff8f1a010) at hw/qdev.c:785
#6  0x00007ffff7dee30f in object_unparent (obj=0x7ffff8f1a010) at qom/object.c:370
#7  0x00007ffff7d093b0 in acpi_piix_eject_slot (s=0x7ffff8ed6bd0, slots=<value optimized out>)
    at hw/acpi_piix4.c:306
#8  0x00007ffff7e7ae20 in access_with_adjusted_size (addr=8, value=0x7fffefffec88, size=4, 
    access_size_min=<value optimized out>, access_size_max=<value optimized out>, access=
    0x7ffff7e7c590 <memory_region_write_accessor>, opaque=0x7ffff8ed73d8)
    at /home/mst/scm/qemu/memory.c:364
#9  0x00007ffff7e7b44b in memory_region_iorange_write (iorange=<value optimized out>, 
    offset=<value optimized out>, width=<value optimized out>, data=128)
    at /home/mst/scm/qemu/memory.c:439
#10 0x00007ffff7e7a39c in kvm_handle_io (env=0x7ffff8d27a80)
    at /home/mst/scm/qemu/kvm-all.c:1432
#11 kvm_cpu_exec (env=0x7ffff8d27a80) at /home/mst/scm/qemu/kvm-all.c:1581
#12 0x00007ffff7e28971 in qemu_kvm_cpu_thread_fn (arg=0x7ffff8d27a80)
    at /home/mst/scm/qemu/cpus.c:759
#13 0x00007ffff681f851 in start_thread () from /lib64/libpthread.so.0
#14 0x00007ffff59326dd in clone () from /lib64/libc.so.6
(gdb) frame 4
#4  0x00007ffff7deef76 in object_get_canonical_path (obj=0x7ffff8f1a010) at qom/object.c:1011
1011            g_assert(prop != NULL);
(gdb) p obj
$1 = (Object *) 0x7ffff8f1a010
(gdb) p (DeviceState*)obj
$2 = (DeviceState *) 0x7ffff8f1a010
(gdb) p $2
$3 = (DeviceState *) 0x7ffff8f1a010
(gdb) p *$2
$4 = {parent_obj = {class = 0x7ffff8ede8f0, free = 0x7ffff735f5b0 <g_free>, properties = {
      tqh_first = 0x7ffff8eec8a0, tqh_last = 0x7ffff8f1dc00}, ref = 1, parent = 
    0x7ffff8c81d00}, id = 0x7ffff8ba6710 "bah", realized = true, opts = 0x7ffff8ba66c0, 
  hotplugged = 0, parent_bus = 0x0, num_gpio_out = 0, gpio_out = 0x0, num_gpio_in = 0, 
  gpio_in = 0x0, child_bus = {lh_first = 0x0}, num_child_bus = 0, instance_id_alias = -1, 
  alias_required_for_version = 0}
(gdb) 
$5 = {parent_obj = {class = 0x7ffff8ede8f0, free = 0x7ffff735f5b0 <g_free>, properties = {
      tqh_first = 0x7ffff8eec8a0, tqh_last = 0x7ffff8f1dc00}, ref = 1, parent = 
    0x7ffff8c81d00}, id = 0x7ffff8ba6710 "bah", realized = true, opts = 0x7ffff8ba66c0, 
  hotplugged = 0, parent_bus = 0x0, num_gpio_out = 0, gpio_out = 0x0, num_gpio_in = 0, 
  gpio_in = 0x0, child_bus = {lh_first = 0x0}, num_child_bus = 0, instance_id_alias = -1, 
  alias_required_for_version = 0}
(gdb) 
$6 = {parent_obj = {class = 0x7ffff8ede8f0, free = 0x7ffff735f5b0 <g_free>, properties = {
      tqh_first = 0x7ffff8eec8a0, tqh_last = 0x7ffff8f1dc00}, ref = 1, parent = 
    0x7ffff8c81d00}, id = 0x7ffff8ba6710 "bah", realized = true, opts = 0x7ffff8ba66c0, 
  hotplugged = 0, parent_bus = 0x0, num_gpio_out = 0, gpio_out = 0x0, num_gpio_in = 0, 
  gpio_in = 0x0, child_bus = {lh_first = 0x0}, num_child_bus = 0, instance_id_alias = -1, 
  alias_required_for_version = 0}

-- 
MST