The ``opened=on`` option in the command line or QMP ``object-add`` either had
no effect (if ``opened`` was the last option) or caused errors.  The property
is therefore useless and was deprecated in 6.0; make it read-only now.

Based-on: <20220509101907.212687-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 backends/rng.c                  | 18 ++----------------
 docs/about/deprecated.rst       |  9 ---------
 docs/about/removed-features.rst |  7 +++++++
 3 files changed, 9 insertions(+), 25 deletions(-)

diff --git a/backends/rng.c b/backends/rng.c
index 3757b04485..6c7bf64426 100644
--- a/backends/rng.c
+++ b/backends/rng.c
@@ -48,24 +48,10 @@ static bool rng_backend_prop_get_opened(Object *obj, Error **errp)
 
 static void rng_backend_complete(UserCreatable *uc, Error **errp)
 {
-    object_property_set_bool(OBJECT(uc), "opened", true, errp);
-}
-
-static void rng_backend_prop_set_opened(Object *obj, bool value, Error **errp)
-{
-    RngBackend *s = RNG_BACKEND(obj);
+    RngBackend *s = RNG_BACKEND(uc);
     RngBackendClass *k = RNG_BACKEND_GET_CLASS(s);
     Error *local_err = NULL;
 
-    if (value == s->opened) {
-        return;
-    }
-
-    if (!value && s->opened) {
-        error_setg(errp, QERR_PERMISSION_DENIED);
-        return;
-    }
-
     if (k->opened) {
         k->opened(s, &local_err);
         if (local_err) {
@@ -122,7 +108,7 @@ static void rng_backend_class_init(ObjectClass *oc, void *data)
 
     object_class_property_add_bool(oc, "opened",
                                    rng_backend_prop_get_opened,
-                                   rng_backend_prop_set_opened);
+                                   NULL);
 }
 
 static const TypeInfo rng_backend_info = {
diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index 2feb0c506c..25bc92dc65 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -90,15 +90,6 @@ the process listing. This is replaced by the new ``password-secret``
 option which lets the password be securely provided on the command
 line using a ``secret`` object instance.
 
-``opened`` property of ``rng-*`` objects (since 6.0)
-''''''''''''''''''''''''''''''''''''''''''''''''''''
-
-The only effect of specifying ``opened=on`` in the command line or QMP
-``object-add`` is that the device is opened immediately, possibly before all
-other options have been processed.  This will either have no effect (if
-``opened`` was the last option) or cause errors.  The property is therefore
-useless and should not be specified.
-
 ``-display sdl,window_close=...`` (since 6.1)
 '''''''''''''''''''''''''''''''''''''''''''''
 
diff --git a/docs/about/removed-features.rst b/docs/about/removed-features.rst
index 2032608314..715b5f4f4d 100644
--- a/docs/about/removed-features.rst
+++ b/docs/about/removed-features.rst
@@ -749,6 +749,13 @@ no effect (if ``loaded`` was the last option) or caused options to be
 effectively ignored as if they were not given.  The property is therefore
 useless and should simply be removed.
 
+``opened`` property of ``rng-*`` objects (removed in 7.1)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The ``opened=on`` option in the command line or QMP ``object-add`` either had
+no effect (if ``opened`` was the last option) or caused errors.  The property
+is therefore useless and should not be specified.
+
 Block devices
 -------------
 
-- 
2.35.1