Fix fenced Present freezes without disabling asynchronous rendering

debian/patches/0005-present-disarm-wait-fence-before-re-execution.patch

@@ -0,0 +1,33 @@
+From: KiralyCraft <alexucu@gmail.com>
+Subject: present: disarm the wait-fence callback before re-execution
+
+A fence notification is one-shot, but re_execute() can leave the Present
+request alive while it waits for its target MSC. Clear the callback before
+re-entering the execution path. If that path must wait again, it installs
+a new callback itself.
+
+This is required when the Sync trigger walker restarts after a callback:
+otherwise a still-live request can be called repeatedly in the same scan.
+It also prevents a later trigger of a reused fence from executing the old
+request again.
+
+The same callback-lifetime correction is used by Termux:X11:
+https://github.com/KiralyCraft/termux-x11/commit/fc534e514d7ad4851d0aca3357495816260e4549
+---
+ present/present_execute.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/present/present_execute.c b/present/present_execute.c
+--- a/present/present_execute.c
++++ b/present/present_execute.c
+@@ -38,6 +38,10 @@ present_wait_fence_triggered(void *param)
+     ScreenPtr               screen = vblank->screen;
+     present_screen_priv_ptr screen_priv = present_screen_priv(screen);
+
++    /* Re-execution may keep this request alive until its target MSC.
++     * Disarm this notification; a new wait will install a new callback. */
++    present_fence_set_callback(vblank->wait_fence, NULL, NULL);
++
+     screen_priv->re_execute(vblank);
+ }
+

debian/patches/0006-miext-sync-restart-trigger-scan-after-callback.patch

@@ -0,0 +1,49 @@
+From: Olivier Fourdan <ofourdan@redhat.com>
+Subject: miext/sync: restart the trigger scan after a callback
+Origin: upstream, https://gitlab.freedesktop.org/xorg/xserver/-/commit/f19ab94ba9c891d801231654267556dc7f32b5e0
+
+Backport upstream's trigger-list lifetime correction. A callback can remove
+other entries as well as its own entry, so saving the next pointer before
+calling it is not sufficient. Restart from the current list head instead.
+
+Apply after the Present one-shot callback correction, so a request that
+survives re-execution cannot keep firing in the restart scan.
+
+Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
+Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
+---
+ miext/sync/misync.c | 18 ++++++++++++------
+ 1 file changed, 12 insertions(+), 6 deletions(-)
+
+diff --git a/miext/sync/misync.c b/miext/sync/misync.c
+--- a/miext/sync/misync.c
++++ b/miext/sync/misync.c
+@@ -131,16 +131,22 @@ miSyncDestroyFence(SyncFence * pFence)
+ void
+ miSyncTriggerFence(SyncFence * pFence)
+ {
+-    SyncTriggerList *ptl, *pNext;
++    SyncTriggerList *ptl;
++    Bool triggered;
+
+     pFence->funcs.SetTriggered(pFence);
+
+     /* run through triggers to see if any fired */
+-    for (ptl = pFence->sync.pTriglist; ptl; ptl = pNext) {
+-        pNext = ptl->next;
+-        if ((*ptl->pTrigger->CheckTrigger) (ptl->pTrigger, 0))
+-            (*ptl->pTrigger->TriggerFired) (ptl->pTrigger);
+-    }
++    do {
++        triggered = FALSE;
++        for (ptl = pFence->sync.pTriglist; ptl; ptl = ptl->next) {
++            if ((*ptl->pTrigger->CheckTrigger) (ptl->pTrigger, 0)) {
++                (*ptl->pTrigger->TriggerFired) (ptl->pTrigger);
++                triggered = TRUE;
++                break;
++            }
++        }
++    } while (triggered);
+ }
+
+ SyncScreenFuncsPtr

debian/patches/0007-xwayland-present-do-not-rewait-after-copy.patch

@@ -0,0 +1,37 @@
+From: KiralyCraft <alexucu@gmail.com>
+Subject: xwayland: do not reacquire a copied Present pixmap
+
+After a COPY Present, Idle permits the client to reuse the source pixmap
+and reset its wait fence for a later frame. The old request may still be
+queued for its delayed Complete notification. Re-executing that request
+must not wait for the source again, because that now belongs to a different
+presentation.
+
+Waiting a second time can overwrite blocking_event with the old copied
+request. That request subsequently completes without draining blocked_queue,
+leaving newer requests blocked indefinitely.
+
+Only perform acquisition before the copy. The first wait, asynchronous
+render fences, and delayed completion scheduling are unchanged.
+---
+ hw/xwayland/xwayland-present.c | 8 ++++++--
+ 1 file changed, 6 insertions(+), 2 deletions(-)
+
+diff --git a/hw/xwayland/xwayland-present.c b/hw/xwayland/xwayland-present.c
+--- a/hw/xwayland/xwayland-present.c
++++ b/hw/xwayland/xwayland-present.c
+@@ -1048,8 +1048,12 @@ xwl_present_execute(present_vblank_ptr vblank, uint64_t ust, uint64_t crtc_msc)
+     }
+
+ retry:
+-    if (present_execute_wait(vblank, crtc_msc) ||
+-        xwl_present_wait_acquire_fence_avail(xwl_screen, vblank)) {
++    /* The source pixmap is already idle after a copy. Its wait fence may
++     * have been reset for a later Present, so do not acquire it again just
++     * to send this request's delayed completion notification. */
++    if (!event->copy_executed &&
++        (present_execute_wait(vblank, crtc_msc) ||
++         xwl_present_wait_acquire_fence_avail(xwl_screen, vblank))) {
+         if (!notify_only)
+             /* block execution of subsequent requests until this request is ready */
+             xwl_present_window->blocking_event = event->vblank.event_id;

debian/patches/series

@@ -2,3 +2,6 @@
 0002-xwayland-glamor-add-KGSL-surfaceless-backend-path.patch
 0003-xwayland-dri3-support-KGSL-surfaceless-client-render.patch
 0004-xwayland-scope-KGSL-frame-callback-recovery-per-window.patch
+0005-present-disarm-wait-fence-before-re-execution.patch
+0006-miext-sync-restart-trigger-scan-after-callback.patch
+0007-xwayland-present-do-not-rewait-after-copy.patch