Problem with new Xorg, radeon & compiz/Kwin revisited

[matt]

A while back, I was having a strange issue with the new Xorg and compiz.
In a nutshell, closing certain windows caused Xorg to exit on nasty
signals. At the same time, a few users with Radeon cards were having
issues with Kwin disabling opengl for no apparent reason.

After some research, I had posted a patch seen in a debian mailing list
as a possible solution, and it did indeed solve the immediate problem of
crashing Xorg (and later I found out Kwin worked with OpenGL effects
when the patch is applied).

It was requested I file a PR but first investigate what issues such a
patch might cause. I'm glad I waited, because there are a few. The
medicine is a little worse than the disease. First, with Compiz & Xfce4,
if X was told to shutdown while the previously affected programs
(xfce4-terminal running under compiz & xfce4 was obvious), the machine
would immediately reboot. This is obviously not good. So usually I would
only logout after closing all windows (except Xfce4-panel and the root
window). This would work, and the machine could be shut down from the TTY.

Recently, I installed KDE4. I was so impressed that I was trying to use
it as my "daily desktop". OpenGL Kwin was working fine. However,
engaging the screen lock would reboot the machine, as well as the
machine occasionally spontaneously rebooting. This was much worse than
the above issue.

The patch had one other odd effect, which was that Dri2 was disabled for
some reason.

I reverted the patch to xorg-server I had been running, and now Kwin
will not start OpenGL mode, because it can't find an ARGBGLX visual. If
Kwin is started alone, OpenGL suprisingly works. Xfce4+compiz crashes
Xorg as before, however Dri2 is now enabled. The signal is a segfault at
0x0. AIGLX on/off have no effect.

Here was the patch (I applied it manually looking at the file, the
offsets are wrong for us):

diff --git a/glx/glxdri.c b/glx/glxdri.c
index 326f539..f6ef784 100644
--- a/glx/glxdri.c
+++ b/glx/glxdri.c
@@ -230,7 +230,7 @@ __glXDRIdrawableDestroy(__GLXdrawable *drawable)

      /* If the X window was destroyed, the dri DestroyWindow hook will
       * aready have taken care of this, so only call if pDraw isn't
NULL. */
-    if (drawable->pDraw != NULL) {
+    if (drawable->pDraw != NULL&& drawable->pDraw->type ==
DRAWABLE_WINDOW) {
      screen = (__GLXDRIscreen *) glxGetScreen(drawable->pDraw->pScreen);
(*screen->core->destroyDrawable)(private->driDrawable);

It seems like this shouldn't be having as much effect as it does. I can
only guess the reboots are from memory problems resulting from lingering
drawables? I can't explain the Dri2 interaction, nor can I explain
Kwin's behavior (fairly new to KDE, last time I used it was last century
:) ).

For what it's worth, my driver is xf86-video-ati on a Radeon HD4650.
I'm thoroughly confused by this problem and I'd welcome some help trying
to solve the bug. Anyone else seeing problems with RV710 radeons and
OpenGL compositing?

Matt