From 83b7b17b64b3e42a87f524ac3504be81789ec0fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20=C3=85dahl?= <jadahl@gmail.com>
Date: Fri, 24 Aug 2018 12:56:31 +0200
Subject: [PATCH 19/75] window: Force update monitor on hot plugs

Commit a3da4b8d5bd217c0262fd9361036877d155a300f changed updating of
window monitors to always use take affect when it was done from a
non-user operation. This could cause feed back loops when a non-user
driven operation would trigger the changing of a monitor, which itself
would trigger changing of the monitor again due to a window scale
change.

The reason for the change, was that when the window monitor changed due
to a hot plug, if it didn't actually change, eventually the window
monitor pointer would be pointing to freed memory.

Instead of force updating the monitor on all non-user operations, just
do it on hot plugs. This allows for the feedback loop preventing logic
to still do what its supposed to do, without risking dangling pointers
on hot plugs.

Related: https://gitlab.gnome.org/GNOME/mutter/issues/189
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/192

(cherry picked from commit 8d3e053059cd202e740076caedfc8e3ac149066a)
---
 src/core/window-private.h         | 1 +
 src/core/window.c                 | 4 ++--
 src/wayland/meta-window-wayland.c | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/core/window-private.h b/src/core/window-private.h
index bed2fc7f6..8552829b2 100644
--- a/src/core/window-private.h
+++ b/src/core/window-private.h
@@ -125,6 +125,7 @@ typedef enum _MetaWindowUpdateMonitorFlags
 {
   META_WINDOW_UPDATE_MONITOR_FLAGS_NONE = 0,
   META_WINDOW_UPDATE_MONITOR_FLAGS_USER_OP = 1 << 0,
+  META_WINDOW_UPDATE_MONITOR_FLAGS_FORCE = 1 << 1,
 } MetaWindowUpdateMonitorFlags;
 
 typedef struct _MetaPlacementRule
diff --git a/src/core/window.c b/src/core/window.c
index 5547169d8..d69720a4d 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -3805,7 +3805,7 @@ meta_window_update_for_monitors_changed (MetaWindow *window)
   if (window->override_redirect || window->type == META_WINDOW_DESKTOP)
     {
       meta_window_update_monitor (window,
-                                  META_WINDOW_UPDATE_MONITOR_FLAGS_NONE);
+                                  META_WINDOW_UPDATE_MONITOR_FLAGS_FORCE);
       return;
     }
 
@@ -3841,7 +3841,7 @@ meta_window_update_for_monitors_changed (MetaWindow *window)
   else
     {
       meta_window_update_monitor (window,
-                                  META_WINDOW_UPDATE_MONITOR_FLAGS_NONE);
+                                  META_WINDOW_UPDATE_MONITOR_FLAGS_FORCE);
     }
 }
 
diff --git a/src/wayland/meta-window-wayland.c b/src/wayland/meta-window-wayland.c
index 544c60b5b..e837215de 100644
--- a/src/wayland/meta-window-wayland.c
+++ b/src/wayland/meta-window-wayland.c
@@ -413,7 +413,7 @@ meta_window_wayland_update_main_monitor (MetaWindow                   *window,
       return;
     }
 
-  if (flags & META_WINDOW_UPDATE_MONITOR_FLAGS_USER_OP)
+  if (flags & META_WINDOW_UPDATE_MONITOR_FLAGS_FORCE)
     {
       window->monitor = to;
       return;
-- 
2.21.0