[PATCH] dri2: SourceOffloads may be for DRI3 only

[Chris Wilson]

As a DDX may declare offload support without supporting DRI2
(because it is using an alternative acceleration mechanism like DRI3),
when iterating the list of offload_source Screens to find a matching
DRI2 provider we need to check before assuming it is DRI2 capable.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88514
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Ilia Mirkin <imirkin at alum.mit.edu>
Cc: Dave Airlie <airlied at redhat.com>
---
 hw/xfree86/dri2/dri2.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
index 8b94b8f..e048224 100644
--- a/hw/xfree86/dri2/dri2.c
+++ b/hw/xfree86/dri2/dri2.c
@@ -158,6 +158,9 @@ GetScreenPrime(ScreenPtr master, int prime_id)
         DRI2ScreenPtr ds;
 
         ds = DRI2GetScreen(slave);
+        if (ds == NULL)
+            continue;
+
         if (ds->prime_id == prime_id)
             return slave;
     }
-- 
2.1.4