[PATCH] avoid a potential endless loop.

[Xiang, Haihao]

Previously it is possible that creating rotation data, then cleaning
up and creating again so that pScreen->BlockHandler and
xf86_config->BlockHandler all point to xf86RotateBlockHandler.
See bug #19343.
---
 hw/xfree86/modes/xf86Rotate.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/hw/xfree86/modes/xf86Rotate.c b/hw/xfree86/modes/xf86Rotate.c
index 8e03c6c..21b7aff 100644
--- a/hw/xfree86/modes/xf86Rotate.c
+++ b/hw/xfree86/modes/xf86Rotate.c
@@ -291,6 +291,8 @@ xf86RotateBlockHandler(int screenNum, pointer blockData,
 	/* Re-wrap if rotation is still happening */
 	xf86_config->BlockHandler = pScreen->BlockHandler;
 	pScreen->BlockHandler = xf86RotateBlockHandler;
+    } else {
+	xf86_config->BlockHandler = NULL;
     }
 }
 
@@ -477,8 +479,10 @@ xf86CrtcRotate (xf86CrtcPtr crtc)
 		goto bail2;
 	    
 	    /* Wrap block handler */
-	    xf86_config->BlockHandler = pScreen->BlockHandler;
-	    pScreen->BlockHandler = xf86RotateBlockHandler;
+	    if (!xf86_config->BlockHandler) {
+		xf86_config->BlockHandler = pScreen->BlockHandler;
+		pScreen->BlockHandler = xf86RotateBlockHandler;
+	    }
 	}
 #ifdef RANDR_12_INTERFACE
 	if (transform)
-- 
1.5.4.3