From f587d71f3c91f9ddcc4cdbe8a0f9ce59590d9db2 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 11 Dec 2014 08:53:54 +0000
Subject: [PATCH] sna: Catch NULL RandR screen private

If Xinerama is enabled, than RandR12 will be silently disabled. Be
careful not to dereference the rrScrPiv when it doesn't exist.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87207
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 src/sna/sna_driver.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/sna/sna_driver.c b/src/sna/sna_driver.c
index d4accebf..8a3599c7 100644
--- a/src/sna/sna_driver.c
+++ b/src/sna/sna_driver.c
@@ -1075,8 +1075,10 @@ sna_mode_init(struct sna *sna, ScreenPtr screen)
 
 	/* Wrap RR queries to catch pending MST topology changes */
 	rp = rrGetScrPriv(screen);
-	sna->mode.rrGetInfo = rp->rrGetInfo;
-	rp->rrGetInfo = sna_randr_getinfo;
+	if (rp) {
+		sna->mode.rrGetInfo = rp->rrGetInfo;
+		rp->rrGetInfo = sna_randr_getinfo;
+	}
 
 	return TRUE;
 }