From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43591) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cCQZ9-0007kZ-Go for qemu-devel@nongnu.org; Thu, 01 Dec 2016 07:34:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cCQZ5-0005QX-Ma for qemu-devel@nongnu.org; Thu, 01 Dec 2016 07:34:19 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41954) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cCQZ5-0005Pl-EZ for qemu-devel@nongnu.org; Thu, 01 Dec 2016 07:34:15 -0500 Date: Thu, 1 Dec 2016 12:34:10 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20161201123409.GA6700@work-vm> References: <1480547176-19349-1-git-send-email-mdroth@linux.vnet.ibm.com> <20161201092407.GB9191@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161201092407.GB9191@redhat.com> Subject: Re: [Qemu-devel] [PATCH] monitor: fix object_del for command-line-created objects List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: Michael Roth , qemu-devel@nongnu.org, Markus Armbruster , Eric Blake * Daniel P. Berrange (berrange@redhat.com) wrote: > 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" > > Cc: Markus Armbruster > > Cc: Eric Blake > > Cc: Daniel Berrange > > Signed-off-by: Michael Roth > > --- > > 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. Yes that seems cleaner; the cleanup that's being done is not the result of either of the monitor's actions. Dave > 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/ :| -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK