| Message ID | 1481055300-14239-2-git-send-email-mdroth@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
On Tue, Dec 06, 2016 at 02:14:59PM -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 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" <dgilbert@redhat.com> > Cc: Markus Armbruster <armbru@redhat.com> > Cc: Eric Blake <eblake@redhat.com> > Cc: Daniel Berrange <berrange@redhat.com> > Cc: qemu-stable@nongnu.org > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> > --- > qom/object_interfaces.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c > index ded4d84..23849f9 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) > { > @@ -197,6 +198,7 @@ void user_creatable_del(const char *id, Error **errp) > { > Object *container; > Object *obj; > + QemuOptsList *opt_group; > > container = object_get_objects_root(); > obj = object_resolve_path_component(container, id); > @@ -209,6 +211,15 @@ void user_creatable_del(const char *id, Error **errp) > error_setg(errp, "object '%s' is in use, can not be deleted", id); > return; > } > + > + /* if object was defined on the command-line, remove its corresponding > + * option group entry > + */ > + opt_group = qemu_find_opts_err("object", NULL); > + if (opt_group) { > + qemu_opts_del(qemu_opts_find(opt_group, id)); > + } > + > object_unparent(obj); > } Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Regards, Daniel
Michael Roth <mdroth@linux.vnet.ibm.com> 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=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 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" <dgilbert@redhat.com> > Cc: Markus Armbruster <armbru@redhat.com> > Cc: Eric Blake <eblake@redhat.com> > Cc: Daniel Berrange <berrange@redhat.com> > Cc: qemu-stable@nongnu.org > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> > --- > qom/object_interfaces.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c > index ded4d84..23849f9 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) > { > @@ -197,6 +198,7 @@ void user_creatable_del(const char *id, Error **errp) > { > Object *container; > Object *obj; > + QemuOptsList *opt_group; > > container = object_get_objects_root(); > obj = object_resolve_path_component(container, id); > @@ -209,6 +211,15 @@ void user_creatable_del(const char *id, Error **errp) > error_setg(errp, "object '%s' is in use, can not be deleted", id); > return; > } > + > + /* if object was defined on the command-line, remove its corresponding > + * option group entry > + */ > + opt_group = qemu_find_opts_err("object", NULL); > + if (opt_group) { How can opt_group ever be null? For what it's worth, we assume it can't in hmp_object_add() and main(). > + qemu_opts_del(qemu_opts_find(opt_group, id)); > + } > + > object_unparent(obj); > }
Quoting Markus Armbruster (2016-12-07 04:36:20) > Michael Roth <mdroth@linux.vnet.ibm.com> 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=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 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" <dgilbert@redhat.com> > > Cc: Markus Armbruster <armbru@redhat.com> > > Cc: Eric Blake <eblake@redhat.com> > > Cc: Daniel Berrange <berrange@redhat.com> > > Cc: qemu-stable@nongnu.org > > Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> > > --- > > qom/object_interfaces.c | 11 +++++++++++ > > 1 file changed, 11 insertions(+) > > > > diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c > > index ded4d84..23849f9 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) > > { > > @@ -197,6 +198,7 @@ void user_creatable_del(const char *id, Error **errp) > > { > > Object *container; > > Object *obj; > > + QemuOptsList *opt_group; > > > > container = object_get_objects_root(); > > obj = object_resolve_path_component(container, id); > > @@ -209,6 +211,15 @@ void user_creatable_del(const char *id, Error **errp) > > error_setg(errp, "object '%s' is in use, can not be deleted", id); > > return; > > } > > + > > + /* if object was defined on the command-line, remove its corresponding > > + * option group entry > > + */ > > + opt_group = qemu_find_opts_err("object", NULL); > > + if (opt_group) { > > How can opt_group ever be null? > > For what it's worth, we assume it can't in hmp_object_add() and main(). I was trying to avoid as many assumptions as possible since user_creatable_complete() is kind of reaching out of it's scope here. If we ever changed the behavior on the parsing side this could result in a segfault that might slip through if this particular scenario isn't specifically tested. However, that's less of a concern now thanks to the unit tests that Daniel suggested which would catch this breakage. So that kind of handles my concerns. Will change it for v3. > > > + qemu_opts_del(qemu_opts_find(opt_group, id)); > > + } > > + > > object_unparent(obj); > > } >
diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c index ded4d84..23849f9 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) { @@ -197,6 +198,7 @@ void user_creatable_del(const char *id, Error **errp) { Object *container; Object *obj; + QemuOptsList *opt_group; container = object_get_objects_root(); obj = object_resolve_path_component(container, id); @@ -209,6 +211,15 @@ void user_creatable_del(const char *id, Error **errp) error_setg(errp, "object '%s' is in use, can not be deleted", id); return; } + + /* if object was defined on the command-line, remove its corresponding + * option group entry + */ + opt_group = qemu_find_opts_err("object", NULL); + if (opt_group) { + qemu_opts_del(qemu_opts_find(opt_group, id)); + } + object_unparent(obj); }
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 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" <dgilbert@redhat.com> Cc: Markus Armbruster <armbru@redhat.com> Cc: Eric Blake <eblake@redhat.com> Cc: Daniel Berrange <berrange@redhat.com> Cc: qemu-stable@nongnu.org Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> --- qom/object_interfaces.c | 11 +++++++++++ 1 file changed, 11 insertions(+)