From 3dcceb506b427b42927c33fc44f23f5ce7bdd106 Mon Sep 17 00:00:00 2001
From: hujianwei <hujianwei@localhost.localdomain>
Date: Sun, 6 Nov 2022 05:09:57 +0000
Subject: [PATCH] Fix subsurface commit behavior

* subsurface.c (EarlyCommit): Clear pending_commit after merging
cached state.
* tests/subsurface_test.c (test_single_step): Add test that
found this problem.
---
 subsurface.c            | 13 +++++++++----
 tests/subsurface_test.c | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/subsurface.c b/subsurface.c
index 734410b..7e779be 100644
--- a/subsurface.c
+++ b/subsurface.c
@@ -592,10 +592,15 @@ EarlyCommit (Surface *surface, Role *role)
       return False;
     }
   else if (subsurface->pending_commit)
-    /* There is still pending state.  Merge the state into the surface
-       first, before SubcompositorUpdate is called by
-       InternalCommit.  */
-    XLSurfaceMergeCachedState (surface);
+    {
+      /* There is still cached state.  Merge the state into the
+	 surface first, before SubcompositorUpdate is called by
+	 InternalCommit.  */
+      XLSurfaceMergeCachedState (surface);
+
+      /* As the state is merged, there is no more cached state.  */
+      subsurface->pending_commit = False;
+    }
 
   return True;
 }
diff --git a/tests/subsurface_test.c b/tests/subsurface_test.c
index 0e68d27..6d8c0dc 100644
--- a/tests/subsurface_test.c
+++ b/tests/subsurface_test.c
@@ -685,6 +685,24 @@ test_single_step (enum test_kind kind)
 				       WL_OUTPUT_TRANSFORM_90);
       wait_frame_callback (subsurfaces[8]->surface);
       sleep_or_verify ();
+
+      /* Now, attach subsurface_1.png in subsurfaces[7].  Nothing
+	 should be displayed.  */
+      wl_surface_attach (subsurfaces[7]->surface, subsurface_1_png,
+			 0, 0);
+      wl_surface_damage (subsurfaces[7]->surface, 0, 0, 256, 256);
+      wl_surface_commit (subsurfaces[7]->surface);
+
+      /* Also move the subsurface a little.  */
+      wl_subsurface_set_position (subsurfaces[7]->subsurface, 100, 100);
+
+      wait_frame_callback (wayland_surface);
+      sleep_or_verify ();
+
+      /* Commit subsurfaces[6].  As it is now desynchronous,
+	 subsurface_1.png should be displayed.  */
+      wait_frame_callback (subsurfaces[6]->surface);
+      sleep_or_verify ();
       break;
     }