Commit 9a6d1ac assumed that 'qom-type' could be removed from QemuOpts
with no ill effects.  However, this command line proves otherwise:

$ ./x86_64-softmmu/qemu-system-x86_64 -nodefaults -nographic -qmp stdio \
  -object rng-random,filename=/dev/urandom,id=rng0 \
  -device virtio-rng-pci,rng=rng0
qemu-system-x86_64: -object rng-random,filename=/dev/urandom,id=rng0: Parameter 'qom-type' is missing

Fix the regression by restoring qom-type in opts after its temporary
removal that was needed for the duration of user_creatable_add_opts().

Reported-by: Richard W. M. Jones <rjones@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 qom/object_interfaces.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
index 9c271ad..d4253a8 100644
--- a/qom/object_interfaces.c
+++ b/qom/object_interfaces.c
@@ -122,6 +122,7 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error **errp)
     }
     if (!id) {
         error_setg(errp, QERR_MISSING_PARAMETER, "id");
+        qemu_opt_set(opts, "qom-type", type, &error_abort);
         g_free(type);
         return NULL;
     }
@@ -134,6 +135,7 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error **errp)
     visit_free(v);

     qemu_opts_set_id(opts, (char *) id);
+    qemu_opt_set(opts, "qom-type", type, &error_abort);
     g_free(type);
     QDECREF(pdict);
     return obj;
-- 
2.9.3

On Thu, Mar 23, 2017 at 11:03:15AM -0500, Eric Blake wrote:
> Commit 9a6d1ac assumed that 'qom-type' could be removed from QemuOpts
> with no ill effects.  However, this command line proves otherwise:
> 
> $ ./x86_64-softmmu/qemu-system-x86_64 -nodefaults -nographic -qmp stdio \
>   -object rng-random,filename=/dev/urandom,id=rng0 \
>   -device virtio-rng-pci,rng=rng0
> qemu-system-x86_64: -object rng-random,filename=/dev/urandom,id=rng0: Parameter 'qom-type' is missing
> 
> Fix the regression by restoring qom-type in opts after its temporary
> removal that was needed for the duration of user_creatable_add_opts().
> 
> Reported-by: Richard W. M. Jones <rjones@redhat.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  qom/object_interfaces.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
> index 9c271ad..d4253a8 100644
> --- a/qom/object_interfaces.c
> +++ b/qom/object_interfaces.c
> @@ -122,6 +122,7 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error **errp)
>      }
>      if (!id) {
>          error_setg(errp, QERR_MISSING_PARAMETER, "id");
> +        qemu_opt_set(opts, "qom-type", type, &error_abort);
>          g_free(type);
>          return NULL;
>      }
> @@ -134,6 +135,7 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error **errp)
>      visit_free(v);
> 
>      qemu_opts_set_id(opts, (char *) id);
> +    qemu_opt_set(opts, "qom-type", type, &error_abort);
>      g_free(type);
>      QDECREF(pdict);
>      return obj;

Thanks Eric.  Yes, this fixes the problem I observed before
with libguestfs.

Tested-by: Richard W.M. Jones <rjones@redhat.com>

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://people.redhat.com/~rjones/virt-df/

On 03/23/17 17:03, Eric Blake wrote:
> Commit 9a6d1ac assumed that 'qom-type' could be removed from QemuOpts
> with no ill effects.  However, this command line proves otherwise:
> 
> $ ./x86_64-softmmu/qemu-system-x86_64 -nodefaults -nographic -qmp stdio \
>   -object rng-random,filename=/dev/urandom,id=rng0 \
>   -device virtio-rng-pci,rng=rng0
> qemu-system-x86_64: -object rng-random,filename=/dev/urandom,id=rng0: Parameter 'qom-type' is missing
> 
> Fix the regression by restoring qom-type in opts after its temporary
> removal that was needed for the duration of user_creatable_add_opts().
> 
> Reported-by: Richard W. M. Jones <rjones@redhat.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  qom/object_interfaces.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/qom/object_interfaces.c b/qom/object_interfaces.c
> index 9c271ad..d4253a8 100644
> --- a/qom/object_interfaces.c
> +++ b/qom/object_interfaces.c
> @@ -122,6 +122,7 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error **errp)
>      }
>      if (!id) {
>          error_setg(errp, QERR_MISSING_PARAMETER, "id");
> +        qemu_opt_set(opts, "qom-type", type, &error_abort);
>          g_free(type);
>          return NULL;
>      }
> @@ -134,6 +135,7 @@ Object *user_creatable_add_opts(QemuOpts *opts, Error **errp)
>      visit_free(v);
> 
>      qemu_opts_set_id(opts, (char *) id);
> +    qemu_opt_set(opts, "qom-type", type, &error_abort);
>      g_free(type);
>      QDECREF(pdict);
>      return obj;
> 

Tested-by: Laszlo Ersek <lersek@redhat.com>