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Violators will be prosecuted for from ; Thu, 15 Dec 2016 10:25:16 -0700 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable From: Michael Roth In-Reply-To: <87oa0h2lfz.fsf@dusky.pond.sub.org> References: <1481306681-5760-1-git-send-email-mdroth@linux.vnet.ibm.com> <1481306681-5760-3-git-send-email-mdroth@linux.vnet.ibm.com> <87oa0h2lfz.fsf@dusky.pond.sub.org> Date: Thu, 15 Dec 2016 11:25:07 -0600 Message-Id: <20161215172507.8381.5184@loki> Subject: Re: [Qemu-devel] [PATCH v3 2/2] monitor: fix object_del for command-line-created objects List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: qemu-devel@nongnu.org, qemu-stable@nongnu.org, dgilbert@redhat.com, bharata.rao@gmail.com, david@gibson.dropbear.id.au Quoting Markus Armbruster (2016-12-12 09:53:20) > Michael Roth writes: > = > > 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=3Dram1,size=3D256M > > > > 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=3Dram1,size=3D256M > > 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 a check in user_creatable_del(), which > > is called by both qmp_object_del() and hmp_object_del() to handle > > the actual object cleanup, 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 > > Cc: qemu-stable@nongnu.org > > Signed-off-by: Michael Roth > > Reviewed-by: Daniel P. Berrange > > --- > > qom/object_interfaces.c | 7 +++++++ > > tests/check-qom-proplist.c | 4 ++-- > > 2 files changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c > > index ded4d84..b462a74 100644 > > --- a/qom/object_interfaces.c > > +++ b/qom/object_interfaces.c > > @@ -5,6 +5,7 @@ > > #include "qapi-visit.h" > > #include "qapi/qobject-output-visitor.h" > > #include "qapi/opts-visitor.h" > > +#include "qemu/config-file.h" > > = > > void user_creatable_complete(Object *obj, Error **errp) > > { > > @@ -209,6 +210,12 @@ void user_creatable_del(const char *id, Error **er= rp) > > error_setg(errp, "object '%s' is in use, can not be deleted", = id); > > return; > > } > > + > > + /* if object was defined on the command-line, remove its correspon= ding > > + * option group entry > > + */ > = > Consider adding wings to both ends of multi-line comments. > = > > + qemu_opts_del(qemu_opts_find(qemu_find_opts_err("object", NULL), i= d)); > = > qemu_find_opts_err() can't fail. If it did, qemu_opts_find() would > crash. Okay. > = > Elsewhere, we use qemu_opts_find(qemu_find_opts(NAME)), which would > report an error to stderr / monitor before crashing. Also okay. > = > Perhaps the cleanest (but not the tersest) way to skin this cat: > qemu_opts_find(qemu_find_opts_err(&error_abort)). > = > Your choice. > = > > + > > object_unparent(obj); > > } > > = > > diff --git a/tests/check-qom-proplist.c b/tests/check-qom-proplist.c > > index e3f56ca..c5d4b60 100644 > > --- a/tests/check-qom-proplist.c > > +++ b/tests/check-qom-proplist.c > > @@ -437,9 +437,9 @@ static void test_dummy_createcmdl(void) > > * check for this in user_creatable_del() and remove the QemuOpts = if > > * it is present. > > * > > - * FIXME: add an assert to verify that the QemuOpts is cleaned up > > - * once the corresponding cleanup code is added. > > + * The below check ensures this works as expected. > > */ > > + g_assert(qemu_opts_find(&qemu_object_opts, "dev0") =3D=3D NULL); > = > There's also g_assert_null(), which could result in a more helpful > message when the assertion fails. Your choice. Thanks for the suggestions; I've incorporated all of them into v4. > = > > } > > = > > static void test_dummy_badenum(void) >=20