On Wed, Nov 30, 2016 at 05:06:16PM -0600, Michael Roth wrote: > Currently objects specified on the command-line are only partially > cleaned up when 'object_del' is issued in either HMP or QMP: the > object itself is fully finalized, but the QemuOpts are not removed. > This results in the following behavior: > > x86_64-softmmu/qemu-system-x86_64 -monitor stdio \ > -object memory-backend-ram,id=ram1,size=256M > > QEMU 2.7.91 monitor - type 'help' for more information > (qemu) object_del ram1 > (qemu) object_del ram1 > object 'ram1' not found > (qemu) object_add memory-backend-ram,id=ram1,size=256M > Duplicate ID 'ram1' for object > Try "help object_add" for more information > > which can be an issue for use-cases like memory hotplug. > > This happens on the HMP side because hmp_object_add() attempts to > create a temporary QemuOpts entry with ID 'ram1', which ends up > conflicting with the command-line-created entry, since it was never > cleaned up during the previous hmp_object_del() call. > > We address this by adding checks in {qmp,hmp}_object_del to determine > whether an option group entry matching the object's ID is present, > and removing it if it is. > > Note that qmp_object_add() never attempts to create a temporary > QemuOpts entry, so it does not encounter the duplicate ID error, > which is why this isn't generally visible in libvirt. > > Cc: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > Cc: Markus Armbruster <arm...@redhat.com> > Cc: Eric Blake <ebl...@redhat.com> > Cc: Daniel Berrange <berra...@redhat.com> > Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com> > --- > hmp.c | 10 ++++++++++ > qmp.c | 10 ++++++++++ > 2 files changed, 20 insertions(+) > > diff --git a/hmp.c b/hmp.c > index b869617..99b8bf3 100644 > --- a/hmp.c > +++ b/hmp.c > @@ -2072,6 +2072,16 @@ void hmp_object_del(Monitor *mon, const QDict *qdict) > > user_creatable_del(id, &err); > hmp_handle_error(mon, &err); > + > + /* if object was defined on the command-line, remove its corresponding > + * option group entry > + */ > + if (err == NULL) { > + QemuOptsList *opt_group = qemu_find_opts_err("object", &err); > + if (opt_group) { > + qemu_opts_del(qemu_opts_find(opt_group, id)); > + } > + } > } > > void hmp_info_memdev(Monitor *mon, const QDict *qdict) > diff --git a/qmp.c b/qmp.c > index 0028f0b..87c545d 100644 > --- a/qmp.c > +++ b/qmp.c > @@ -686,6 +686,16 @@ void qmp_object_add(const char *type, const char *id, > void qmp_object_del(const char *id, Error **errp) > { > user_creatable_del(id, errp); > + > + /* if object was defined on the command-line, remove its corresponding > + * option group entry > + */ > + if (!(errp && *errp)) { > + QemuOptsList *opt_group = qemu_find_opts_err("object", errp); > + if (opt_group) { > + qemu_opts_del(qemu_opts_find(opt_group, id)); > + } > + } > }
I rather feel like this code ought to be in user_creatable_del(), since all code paths which call user_creatable_del() need to do deal with this scenario. Also I'd like to see a unit test added that exposes this problem and demonstrates the fix - could att it to tests/check-qom-proplist.c Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://entangle-photo.org -o- http://search.cpan.org/~danberr/ :|