Xorg segfaults on i915gm during intel_drv.so init

[Michal Suchanek]

Hello,

maybe this patch would work (to git before reverting).

Can you try on the system where X crashes on startup?

I suspect that under some circumstances the damage destroy is
attempted when screen is not fully initialized, and the X server
crashes while calculating screenDrawable.

Alternatively, this could be wrapped in the damage_registered part but
that would mean that the only way to determine that the screen
structure is in usable state is by checking damage_registered.

Thanks

Michal
-------------- next part --------------
diff --git a/hw/xfree86/modes/xf86Rotate.c b/hw/xfree86/modes/xf86Rotate.c
index f9602fa..74e572f 100644
--- a/hw/xfree86/modes/xf86Rotate.c
+++ b/hw/xfree86/modes/xf86Rotate.c
@@ -272,7 +272,7 @@ xf86RotateDestroy(xf86CrtcPtr crtc)
     ScrnInfoPtr pScrn = crtc->scrn;
     ScreenPtr pScreen = pScrn->pScreen;
     xf86CrtcConfigPtr xf86_config = XF86_CRTC_CONFIG_PTR(pScrn);
-    DrawablePtr screenDrawable = &pScreen->root->drawable;
+    DrawablePtr screenDrawable = NULL;
     int c;
 
     /* Free memory from rotation */
@@ -290,10 +290,12 @@ xf86RotateDestroy(xf86CrtcPtr crtc)
     /*
      * Clean up damage structures when no crtcs are rotated
      */
+    if (pScreen && pScreen->root)
+        screenDrawable = &pScreen->root->drawable;
     if (screenDrawable && xf86_config->rotation_damage) {
         /* Free damage structure */
         if (xf86_config->rotation_damage_registered) {
-            DamageUnregister(&pScreen->root->drawable,
+            DamageUnregister(screenDrawable,
                              xf86_config->rotation_damage);
             xf86_config->rotation_damage_registered = FALSE;
             DisableLimitedSchedulingLatency();