ui/dbus: fix filtering all update messages

Filtering pending messages when a new scanout is given shouldn't discard
pending cursor changes, for example.

Since filtering happens in a different thread, use atomic set/get.

Fixes: fa88b85dea ("ui/dbus: filter out pending messages when scanout")

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-ID: <20241008125028.1177932-6-marcandre.lureau@redhat.com>
(cherry picked from commit cf59889781297a5618f1735a5f31402caa806b42)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

ui/dbus-listener.c

@@ -26,6 +26,7 @@
 #include "qapi/error.h"
 #include "sysemu/sysemu.h"
 #include "dbus.h"
+#include "glib.h"
 #ifdef G_OS_UNIX
 #include <gio/gunixfdlist.h>
 #endif
@@ -85,7 +86,7 @@ struct _DBusDisplayListener {
 #endif
 
     guint dbus_filter;
-    guint32 out_serial_to_discard;
+    guint32 display_serial_to_discard;
 };
 
 G_DEFINE_TYPE(DBusDisplayListener, dbus_display_listener, G_TYPE_OBJECT)
@@ -93,10 +94,12 @@ G_DEFINE_TYPE(DBusDisplayListener, dbus_display_listener, G_TYPE_OBJECT)
 static void dbus_gfx_update(DisplayChangeListener *dcl,
                             int x, int y, int w, int h);
 
-static void ddl_discard_pending_messages(DBusDisplayListener *ddl)
+static void ddl_discard_display_messages(DBusDisplayListener *ddl)
 {
-    ddl->out_serial_to_discard = g_dbus_connection_get_last_serial(
+    guint32 serial = g_dbus_connection_get_last_serial(
         g_dbus_proxy_get_connection(G_DBUS_PROXY(ddl->proxy)));
+
+    g_atomic_int_set(&ddl->display_serial_to_discard, serial);
 }
 
 #ifdef CONFIG_OPENGL
@@ -290,7 +293,7 @@ static void dbus_scanout_dmabuf(DisplayChangeListener *dcl,
         return;
     }
 
-    ddl_discard_pending_messages(ddl);
+    ddl_discard_display_messages(ddl);
 
     width = qemu_dmabuf_get_width(dmabuf);
     height = qemu_dmabuf_get_height(dmabuf);
@@ -338,7 +341,7 @@ static bool dbus_scanout_map(DBusDisplayListener *ddl)
         return false;
     }
 
-    ddl_discard_pending_messages(ddl);
+    ddl_discard_display_messages(ddl);
 
     if (!qemu_dbus_display1_listener_win32_map_call_scanout_map_sync(
             ddl->map_proxy,
@@ -401,7 +404,7 @@ dbus_scanout_share_d3d_texture(
         return false;
     }
 
-    ddl_discard_pending_messages(ddl);
+    ddl_discard_display_messages(ddl);
 
     qemu_dbus_display1_listener_win32_d3d11_call_scanout_texture2d(
         ddl->d3d11_proxy,
@@ -659,7 +662,7 @@ static void ddl_scanout(DBusDisplayListener *ddl)
         surface_stride(ddl->ds) * surface_height(ddl->ds), TRUE,
         (GDestroyNotify)pixman_image_unref, pixman_image_ref(ddl->ds->image));
 
-    ddl_discard_pending_messages(ddl);
+    ddl_discard_display_messages(ddl);
 
     qemu_dbus_display1_listener_call_scanout(
         ddl->proxy, surface_width(ddl->ds), surface_height(ddl->ds),
@@ -992,17 +995,35 @@ dbus_filter(GDBusConnection *connection,
             gpointer         user_data)
 {
     DBusDisplayListener *ddl = DBUS_DISPLAY_LISTENER(user_data);
-    guint32 serial;
+    guint32 serial, discard_serial;
 
     if (incoming) {
         return message;
     }
 
     serial = g_dbus_message_get_serial(message);
-    if (serial <= ddl->out_serial_to_discard) {
-        trace_dbus_filter(serial, ddl->out_serial_to_discard);
-        g_object_unref(message);
-        return NULL;
+
+    discard_serial = g_atomic_int_get(&ddl->display_serial_to_discard);
+    if (serial <= discard_serial) {
+        const char *member = g_dbus_message_get_member(message);
+        static const char *const display_messages[] = {
+            "Scanout",
+            "Update",
+#ifdef CONFIG_GBM
+            "ScanoutDMABUF",
+            "UpdateDMABUF",
+#endif
+            "ScanoutMap",
+            "UpdateMap",
+            "Disable",
+            NULL,
+        };
+
+        if (g_strv_contains(display_messages, member)) {
+            trace_dbus_filter(serial, discard_serial);
+            g_object_unref(message);
+            return NULL;
+        }
     }
 
     return message;