From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46237) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aK7mw-0001ZL-0N for qemu-devel@nongnu.org; Fri, 15 Jan 2016 12:03:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aK7ms-00039O-Pv for qemu-devel@nongnu.org; Fri, 15 Jan 2016 12:03:49 -0500 Received: from mx2.suse.de ([195.135.220.15]:39889) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aK7ms-00038L-Cm for qemu-devel@nongnu.org; Fri, 15 Jan 2016 12:03:46 -0500 References: <1445253099-16894-1-git-send-email-pbonzini@redhat.com> <87ziytehr2.fsf@blackfin.pond.sub.org> <563B4629.10903@suse.de> <563B49C1.9080305@redhat.com> <87a8qswr33.fsf@blackfin.pond.sub.org> From: =?UTF-8?Q?Andreas_F=c3=a4rber?= Message-ID: <5699266B.7080209@suse.de> Date: Fri, 15 Jan 2016 18:03:39 +0100 MIME-Version: 1.0 In-Reply-To: <87a8qswr33.fsf@blackfin.pond.sub.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] qdev: free qemu-opts when the QOM path goes away List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org, Markus Armbruster , "Michael S. Tsirkin" Am 05.11.2015 um 13:47 schrieb Markus Armbruster: > Paolo Bonzini writes: >> On 05/11/2015 13:06, Andreas F=C3=A4rber wrote: >>>> 1. Wouldn't it be cleaner to delete dev-opts *before* sending >>>> DEVICE_DELETED? Like this: >>>> >>>> +++ b/hw/core/qdev.c >>>> @@ -1244,6 +1244,9 @@ static void device_unparent(Object *obj) >>>> dev->parent_bus =3D NULL; >>>> } >>>> >>>> + qemu_opts_del(dev->opts); >>>> + dev->opts =3D NULL; >>>> + >>>> /* Only send event if the device had been completely realiz= ed */ >>>> if (dev->pending_deleted_event) { >>>> gchar *path =3D object_get_canonical_path(OBJECT(dev)); >>> >>> To me this proposal sounds sane, but I did not get to tracing the cod= e >>> flow here. Paolo, which approach do you prefer and why? >> >> It doesn't really matter, because the BQL is being held here. >> >> On the other hand, if the opts are deleted in finalize, there is an >> arbitrary delay because finalize is typically called after a >> synchronize_rcu period. >> >>>>> 2. If the device is a block device, then unplugging it also deletes= its >>>>> backend (ugly wart we keep for backward compatibility; *not* for >>>>> blockdev-add, though). This backend also has a QemuOpts. It ge= ts >>>>> deleted in drive_info_del(). Just like device_finalize(), it ru= ns >>>>> within object_unref(), i.e. after DEVICE_DELETED is sent. Same = race, >>>>> different ID, or am I missing something? >>>>> >>>>> See also https://bugzilla.redhat.com/show_bug.cgi?id=3D1256044 >>> >>> If we can leave this patch decoupled from block layer and decide soon= ish >>> on the desired approach, I'd be happy to include it in my upcoming >>> qom-devices pull. >> >> I agree with you, the block layer bug is separate. >=20 > Related, but clearly separate. Mentioning it in the commit message > would be nice, though. Paolo, pong: I gathered that I should queue the original patch without Markus's proposed change, correct? And do you want to add some sentence to the commit message as requested by Markus? Regards, Andreas --=20 SUSE Linux GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany GF: Felix Imend=C3=B6rffer, Jane Smithard, Graham Norton; HRB 21284 (AG N= =C3=BCrnberg)