From c6bc52cb6663138d1273447cb7661fa6e958f539 Mon Sep 17 00:00:00 2001
From: Dave Airlie <airlied@redhat.com>
Date: Mon, 21 Jun 2010 14:08:50 +1000
Subject: [PATCH] dri2: avoid crash with old dri drivers.
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I built latest server and copied over a mesa 7.8 dri2 driver to use with it,
and it crashed in here starting compiz. Looks like we need to validate the
flush extension is registered before calling invalidate.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Michel Dänzer <michel@daenzer.net>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
---
 glx/glxdri2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/glx/glxdri2.c b/glx/glxdri2.c
index 177c73ca2..970a51ae3 100644
--- a/glx/glxdri2.c
+++ b/glx/glxdri2.c
@@ -435,7 +435,8 @@ __glXDRIinvalidateBuffers(DrawablePtr pDraw, void *priv)
     __GLXDRIdrawable *private = priv;
     __GLXDRIscreen *screen = private->screen;
 
-    (*screen->flush->invalidate)(private->driDrawable);
+    if (screen->flush)
+	(*screen->flush->invalidate)(private->driDrawable);
 #endif
 }