manager: make "nmcli net off" wait for deactivations

The current behavior of "nmcli networking off" is that it starts
disconnecting the devices, but doesn't wait for them to actually
come down.

That is not too helpful: the user never knows when the network is
actually disconnected.

Some users, notably the NetworkManager-CI test suite, seem to expect the
devices are all disconnected after the command finishes. Even worse,
it immediately proceeds activating the connections:

    @ovs_cloned_mac_set_on_iface
    ...
    * Execute "nmcli networking off && nmcli networking on"

This results in pure utter chaos. In particular, the slave connections
sometimes refuse to activate after "nmcli networking on", because the
master connections are still getting disconnected in response to
preceding "nmcli networking off".

Let's make Enable(FALSE) and Sleep(TRUE) block until none of the devices
are expected to go down.

Note that this makes those call also return when Enable(TRUE) and
Sleep(FALSE) is issued in meanwhile. Therefore a return from
Enable(FALSE) doesn't necessarily imply the networking is disabled.
This is a feature, not a bug -- the actual manager state is available in
the "state" property.

Fixes-test: @ovs_cloned_mac_set_on_iface

src/core/nm-manager.c

@@ -213,6 +213,10 @@ typedef struct {
 
     unsigned connectivity_check_enabled_last : 2;
 
+    /* List of GDBusMethodInvocation of in progress Sleep() and Enable()
+     * calls. They return only if all in-flight deactivations finished. */
+    GSList *sleep_invocations;
+
     guint delete_volatile_connection_idle_id;
     CList delete_volatile_connection_lst_head;
 } NMManagerPrivate;
@@ -6361,6 +6365,22 @@ done:
     g_clear_object(&subject);
 }
 
+static void
+sleep_devices_check_empty(NMManager *self)
+{
+    NMManagerPrivate      *priv = NM_MANAGER_GET_PRIVATE(self);
+    GDBusMethodInvocation *invocation;
+
+    if (g_hash_table_size(priv->sleep_devices) > 0)
+        return;
+
+    while (priv->sleep_invocations) {
+        invocation = priv->sleep_invocations->data;
+        g_dbus_method_invocation_return_value(invocation, NULL);
+        priv->sleep_invocations = g_slist_remove(priv->sleep_invocations, invocation);
+    }
+}
+
 static gboolean
 sleep_devices_add(NMManager *self, NMDevice *device, gboolean suspending)
 {
@@ -6403,6 +6423,9 @@ sleep_devices_remove(NMManager *self, NMDevice *device)
     g_signal_handlers_disconnect_by_func(device, device_sleep_cb, self);
     g_hash_table_remove(priv->sleep_devices, device);
     g_object_unref(device);
+
+    sleep_devices_check_empty(self);
+
     return TRUE;
 }
 
@@ -6414,9 +6437,6 @@ sleep_devices_clear(NMManager *self)
     NMSleepMonitorInhibitorHandle *handle;
     GHashTableIter                 iter;
 
-    if (!priv->sleep_devices)
-        return;
-
     g_hash_table_iter_init(&iter, priv->sleep_devices);
     while (g_hash_table_iter_next(&iter, (gpointer *) &device, (gpointer *) &handle)) {
         g_signal_handlers_disconnect_by_func(device, device_sleep_cb, self);
@@ -6425,6 +6445,8 @@ sleep_devices_clear(NMManager *self)
         g_object_unref(device);
         g_hash_table_iter_remove(&iter);
     }
+
+    sleep_devices_check_empty(self);
 }
 
 static void
@@ -6653,7 +6675,10 @@ impl_manager_sleep(NMDBusObject                      *obj,
                             TRUE,
                             subject,
                             NULL);
-    g_dbus_method_invocation_return_value(invocation, NULL);
+
+    priv->sleep_invocations = g_slist_prepend(priv->sleep_invocations, invocation);
+    sleep_devices_check_empty(self);
+
     return;
 }
 
@@ -6693,10 +6718,11 @@ _internal_enable(NMManager *self, gboolean enable)
 static void
 enable_net_done_cb(NMAuthChain *chain, GDBusMethodInvocation *context, gpointer user_data)
 {
-    NMManager       *self = NM_MANAGER(user_data);
-    NMAuthCallResult result;
-    gboolean         enable;
-    NMAuthSubject   *subject;
+    NMManager        *self = NM_MANAGER(user_data);
+    NMManagerPrivate *priv = NM_MANAGER_GET_PRIVATE(self);
+    NMAuthCallResult  result;
+    gboolean          enable;
+    NMAuthSubject    *subject;
 
     nm_assert(G_IS_DBUS_METHOD_INVOCATION(context));
 
@@ -6721,8 +6747,10 @@ enable_net_done_cb(NMAuthChain *chain, GDBusMethodInvocation *context, gpointer
     }
 
     _internal_enable(self, enable);
-    g_dbus_method_invocation_return_value(context, NULL);
     nm_audit_log_control_op(NM_AUDIT_OP_NET_CONTROL, enable ? "on" : "off", TRUE, subject, NULL);
+
+    priv->sleep_invocations = g_slist_prepend(priv->sleep_invocations, context);
+    sleep_devices_check_empty(self);
 }
 
 static void
@@ -8336,8 +8364,10 @@ dispose(GObject *object)
 
     g_clear_object(&priv->vpn_manager);
 
-    sleep_devices_clear(self);
-    nm_clear_pointer(&priv->sleep_devices, g_hash_table_unref);
+    if (priv->sleep_devices) {
+        sleep_devices_clear(self);
+        nm_clear_pointer(&priv->sleep_devices, g_hash_table_unref);
+    }
 
     if (priv->sleep_monitor) {
         g_signal_handlers_disconnect_by_func(priv->sleep_monitor, sleeping_cb, self);