From 7b06e468b37164eeaa18fc32cba801de0eee4eb1 Mon Sep 17 00:00:00 2001
From: Olivier Fourdan <ofourdan@redhat.com>
Date: Tue, 4 May 2021 10:56:38 +0200
Subject: [PATCH xserver 19/27] xwayland/eglstream: Do not always increment
 pixmap refcnt on commit
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Currently, the EGLstream backend would increment the pixmap refcount for
each commit, and decrease that refcount on the wl_buffer release
callback.

But that's relying on the compositor sending us a release callback for
each commit, otherwise the pixmap refcount will keep increasing and the
pixmap will be leaked.

So instead, increment the refcount on the pixmap only when we have not
received a release notification for the wl_buffer, to avoid increasing
the pixmap refcount more than once without a corresponding release
event.

This way, if the pixmap is still in use when released on the X11 side,
the EGL stream will be kept until the compositor releases it.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Suggested-by: Michel Dänzer <mdaenzer@redhat.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
(cherry picked from commit d85bfa6ab7495281516f3a4b05dc1ff0b2c4bf91)
---
 hw/xwayland/xwayland-glamor-eglstream.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/hw/xwayland/xwayland-glamor-eglstream.c b/hw/xwayland/xwayland-glamor-eglstream.c
index 6721acfe8..64f4e31f5 100644
--- a/hw/xwayland/xwayland-glamor-eglstream.c
+++ b/hw/xwayland/xwayland-glamor-eglstream.c
@@ -89,6 +89,7 @@ struct xwl_pixmap {
     struct xwl_screen *xwl_screen;
     struct wl_buffer *buffer;
     struct xwl_eglstream_pending_stream *pending_stream;
+    Bool wait_for_buffer_release;
 
     /* XWL_PIXMAP_EGLSTREAM. */
     EGLStreamKHR stream;
@@ -577,8 +578,16 @@ xwl_eglstream_queue_pending_stream(WindowPtr window, PixmapPtr pixmap)
 static void
 xwl_eglstream_buffer_release_callback(void *data)
 {
-    /* drop the reference we took in post_damage, freeing if necessary */
-    dixDestroyPixmap(data, 0);
+    PixmapPtr pixmap = data;
+    struct xwl_pixmap *xwl_pixmap = xwl_pixmap_get(pixmap);
+
+    assert(xwl_pixmap);
+
+    if (xwl_pixmap->wait_for_buffer_release) {
+        xwl_pixmap->wait_for_buffer_release = FALSE;
+        /* drop the reference we took in the ready callback, freeing if necessary */
+        dixDestroyPixmap(pixmap, 0);
+    }
 }
 
 static const struct wl_buffer_listener xwl_eglstream_buffer_release_listener = {
@@ -606,6 +615,7 @@ xwl_eglstream_create_pixmap_and_stream(struct xwl_screen *xwl_screen,
 
     xwl_glamor_egl_make_current(xwl_screen);
 
+    xwl_pixmap->wait_for_buffer_release = FALSE;
     xwl_pixmap->xwl_screen = xwl_screen;
     xwl_pixmap->surface = EGL_NO_SURFACE;
     xwl_pixmap->stream = eglCreateStreamKHR(xwl_screen->egl_display, NULL);
@@ -762,8 +772,11 @@ xwl_glamor_eglstream_post_damage(struct xwl_window *xwl_window,
         goto out;
     }
 
-    /* hang onto the pixmap until the compositor has released it */
-    pixmap->refcnt++;
+    if (!xwl_pixmap->wait_for_buffer_release) {
+        /* hang onto the pixmap until the compositor has released it */
+        pixmap->refcnt++;
+        xwl_pixmap->wait_for_buffer_release = TRUE;
+    }
 
 out:
     /* Restore previous state */
-- 
2.31.1