xlib: Destroy the fallback damage along with the fallback surface

Whenever we discard the fallback surface, we need to destroy the
associated damage tracking, so move this into the common discard
routine.

This should fix the issue when trying to flush the fallback before
the user modifies any foreign Drawables. The current code issued the
flush and then explicitly discard the fallback, but unless it was idle
at the time of the flush the associated damage would not have also been
destroyed. Asserts followed.

References: https://bugs.freedesktop.org/show_bug.cgi?id=54657
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 5 insertions, 8 deletions

diff --git a/src/cairo-xlib-surface.c b/src/cairo-xlib-surface.c
index 58576b822..718f4e731 100644
--- a/src/cairo-xlib-surface.c
+++ b/src/cairo-xlib-surface.c
@@ -370,8 +370,10 @@ _cairo_xlib_surface_discard_shm (cairo_xlib_surface_t *surface)
 
     cairo_surface_finish (surface->shm);
     cairo_surface_destroy (surface->shm);
-
     surface->shm = NULL;
+
+    _cairo_damage_destroy (surface->base.damage);
+    surface->base.damage = NULL;
 }
 
 static cairo_status_t
@@ -1447,13 +1449,8 @@ _cairo_xlib_surface_flush (void *abstract_surface,
 	return status;
 
     surface->fallback >>= 1;
-    if (surface->shm && _cairo_xlib_shm_surface_is_idle (surface->shm)) {
-	cairo_surface_destroy (surface->shm);
-	surface->shm = NULL;
-
-	_cairo_damage_destroy (surface->base.damage);
-	surface->base.damage = NULL;
-    }
+    if (surface->shm && _cairo_xlib_shm_surface_is_idle (surface->shm))
+	_cairo_xlib_surface_discard_shm (surface);
 
     return CAIRO_STATUS_SUCCESS;
 }