From 6d8133e41e3e2c2f2bc65e22675a4c68a8539ac8 Mon Sep 17 00:00:00 2001
From: Randy Li <ayaka@soulik.info>
Date: Thu, 29 Oct 2020 06:13:05 +0000
Subject: [PATCH] waylandsink: release frame callback when destroyed

We would use a frame callback from the surface to indicate
that last buffer is rendered, but when we destroy the surface
and that callback is not back yet, it may cause the wayland event
queue crash.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1729>
---
 ext/wayland/gstwaylandsink.c | 2 ++
 ext/wayland/wlwindow.c       | 4 ++++
 ext/wayland/wlwindow.h       | 1 +
 3 files changed, 7 insertions(+)

diff --git a/ext/wayland/gstwaylandsink.c b/ext/wayland/gstwaylandsink.c
index 8c6fdd0e71..47192df466 100644
--- a/ext/wayland/gstwaylandsink.c
+++ b/ext/wayland/gstwaylandsink.c
@@ -637,6 +637,7 @@ frame_redraw_callback (void *data, struct wl_callback *callback, uint32_t time)
 
   g_mutex_lock (&sink->render_lock);
   sink->redraw_pending = FALSE;
+  sink->window->callback = NULL;
   g_mutex_unlock (&sink->render_lock);
 
   wl_callback_destroy (callback);
@@ -660,6 +661,7 @@ render_last_buffer (GstWaylandSink * sink, gboolean redraw)
 
   sink->redraw_pending = TRUE;
   callback = wl_surface_frame (surface);
+  sink->window->callback = callback;
   wl_callback_add_listener (callback, &frame_callback_listener, sink);
 
   if (G_UNLIKELY (sink->video_info_changed && !redraw)) {
diff --git a/ext/wayland/wlwindow.c b/ext/wayland/wlwindow.c
index 0cf85aa625..3fdf0273bd 100644
--- a/ext/wayland/wlwindow.c
+++ b/ext/wayland/wlwindow.c
@@ -157,6 +157,9 @@ gst_wl_window_finalize (GObject * gobject)
 {
   GstWlWindow *self = GST_WL_WINDOW (gobject);
 
+  if (self->callback)
+    wl_callback_destroy (self->callback);
+
   if (self->wl_shell_surface)
     wl_shell_surface_destroy (self->wl_shell_surface);
 
@@ -197,6 +200,7 @@ gst_wl_window_new_internal (GstWlDisplay * display, GMutex * render_lock)
   window->render_lock = render_lock;
   g_cond_init (&window->configure_cond);
 
+  window->callback = NULL;
   window->area_surface = wl_compositor_create_surface (display->compositor);
   window->video_surface = wl_compositor_create_surface (display->compositor);
 
diff --git a/ext/wayland/wlwindow.h b/ext/wayland/wlwindow.h
index c3f0172166..cecbda6649 100644
--- a/ext/wayland/wlwindow.h
+++ b/ext/wayland/wlwindow.h
@@ -55,6 +55,7 @@ struct _GstWlWindow
   struct wl_shell_surface *wl_shell_surface;
   struct xdg_surface *xdg_surface;
   struct xdg_toplevel *xdg_toplevel;
+  struct wl_callback *callback;
   gboolean configured;
   GCond configure_cond;
   GMutex configure_mutex;