wlserver: Add naive locking to try to see if that fixes hangs for good.

Change the wl event loop to busy-wait for now as that's easiest to make
unlock periodically.

src/steamcompmgr.c

@@ -1416,6 +1416,8 @@ static void
 handle_wl_surface_id(Display *dpy, win *w, long surfaceID)
 {
 	struct wlr_surface *surface = NULL;
+	
+	wlserver_lock();
 
 	struct wl_resource *resource = wl_client_get_object(wlserver.wlr.xwayland->client, surfaceID);
 	if (resource) {
@@ -1424,14 +1426,18 @@ handle_wl_surface_id(Display *dpy, win *w, long surfaceID)
 	else
 	{
 		fprintf (stderr, "wayland surface for window not found, implement pending list for late surface notification\n");
+		wlserver_unlock();
 		return;
 	}
 	
 	if (!wlr_surface_set_role(surface, &xwayland_surface_role, w, NULL, 0))
 	{
 		fprintf (stderr, "Failed to set xwayland surface role");
+		wlserver_unlock();
 		return;
 	}
+	
+	wlserver_unlock();
 		
 	w->wlrsurface = surface;
 }
@@ -1587,7 +1593,9 @@ void check_new_wayland_res(void)
 					// Acknowledge previous one, seems we can get hangs if we don't.
 					struct timespec now;
 					clock_gettime(CLOCK_MONOTONIC, &now);
+					wlserver_lock();
 					wlr_surface_send_frame_done(w->wlrsurface, &now);
+					wlserver_unlock();
 				}
 				
 				w->committed = True;
@@ -2056,7 +2064,9 @@ steamcompmgr_main (int argc, char **argv)
 				if ( w->wlrsurface && w->committed == True )
 				{
 					// Acknowledge commit once.
+					wlserver_lock();
 					wlr_surface_send_frame_done(w->wlrsurface, &now);
+					wlserver_unlock();
 					
 					w->committed = False;
 				}

src/wlserver.c

@@ -3,6 +3,7 @@
 #include <signal.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <pthread.h>
 
 #include <wayland-server-core.h>
 #include <wlr/backend.h>
@@ -164,9 +165,31 @@ int wlserver_init(int argc, char **argv, Bool bIsNested) {
 	return 0;
 }
 
+pthread_mutex_t waylock = PTHREAD_MUTEX_INITIALIZER;
+
+void wlserver_lock(void)
+{
+	pthread_mutex_lock(&waylock);
+}
+
+void wlserver_unlock(void)
+{
+	pthread_mutex_unlock(&waylock);
+}
+
 int wlserver_run(void)
 {
-	wl_display_run(wlserver.wl_display);
+	while ( 1 )
+	{
+		wlserver_lock();
+		wl_display_flush_clients(wlserver.wl_display);
+		int ret = wl_event_loop_dispatch(wlserver.wl_event_loop, 0);
+		wlserver_unlock();
+		if (ret < 0) {
+			break;
+		}
+	}
+
 	// We need to shutdown Xwayland before disconnecting all clients, otherwise
 	// wlroots will restart it automatically.
 	wlr_xwayland_destroy(wlserver.wlr.xwayland);

src/wlserver.h

@@ -46,6 +46,9 @@ int wlserver_run(void);
 
 void nudge_steamcompmgr(void);
 
+void wlserver_lock(void);
+void wlserver_unlock(void);
+
 #ifndef C_SIDE
 }
 #endif