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patches: add traced mutter touch-cancel patches

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Two local-test variants for mutter!5375: the NULL-check fix with
g_message traces, and Jonas Ådahl's proposal to forget a cancelled
touch sequence. They log which path cancelled the touch, to answer
how a resize reaches touch_can_grab_surface() with no focus surface.
Not applied yet; desktop.nix still uses mutter-touch-cancelled-grab.

Assisted-by: Claude:opus-5-5
This commit is contained in:
Sergei Poljanski 2026-10-20 12:10:06 +04:00
commit ebc58d2b2a
Signed by: asxpi
GPG key ID: 4F8851660FA4121B
2 changed files with 156 additions and 0 deletions
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54
patches/mutter-touch-cancel-trace.patch Normal file
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@ -0,0 +1,54 @@
From: asxpi <asxpi@narayana.im>
Subject: [PATCH] wayland/touch: Don't crash on grab requests for cancelled touches (traced)
The same NULL check as mutter-touch-cancelled-grab.patch (mutter!5375):
a touch cancelled while the finger is still down keeps its
MetaWaylandTouchInfo with focus_surface NULL (deliberately, since !5057),
and a grab request with its serial must be refused rather than crash in
touch_can_grab_surface().
LOCAL TEST ONLY: three g_message lines say which path cancelled the touch
(CLUTTER_TOUCH_CANCEL or the seat's focus change) and when a grab for a
cancelled touch was refused, to answer the open question on !5375 of how a
resize reaches touch_can_grab_surface() with no focus surface.
Upstream: https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/5375
---
--- a/src/wayland/meta-wayland-touch.c
+++ b/src/wayland/meta-wayland-touch.c
@@ -524,6 +524,7 @@
break;
case CLUTTER_TOUCH_CANCEL:
+ g_message ("touch-trace: cancel via CLUTTER_TOUCH_CANCEL");
meta_wayland_touch_cancel (touch);
break;
@@ -656,6 +657,13 @@
{
MetaWaylandSurface *subsurface;
+ /* Cleared by meta_wayland_touch_cancel() while the touch is still down */
+ if (!touch_info->focus_surface)
+ {
+ g_message ("touch-trace: grab refused for a cancelled touch");
+ return FALSE;
+ }
+
if (touch_info->focus_surface->surface == surface)
return TRUE;
--- a/src/wayland/meta-wayland-seat.c
+++ b/src/wayland/meta-wayland-seat.c
@@ -259,7 +259,10 @@
sequence = clutter_sprite_get_sequence (CLUTTER_SPRITE (focus));
if (surface != meta_wayland_touch_get_focus_surface (seat->touch, sequence))
- meta_wayland_touch_cancel (seat->touch);
+ {
+ g_message ("touch-trace: cancel via seat focus change");
+ meta_wayland_touch_cancel (seat->touch);
+ }
break;
}