[Mesa-dev] [PATCH 1/3] i965/drm: Fix dereference-before-NULL-check in brw_bo_unmap().

[Kenneth Graunke]

I introduced this when cleaning up this code.  libdrm_intel was fine.
While passing NULL to free() is a common pattern...passing NULL to
unmap seems pretty bad.  You really ought to know whether you have
a buffer or not.  So, we could add an assert.  Not sure whether
that's better.  This takes the defensive plan of bailing early,
which is what libdrm_intel did originally.

CID: 1405006
---
 src/mesa/drivers/dri/i965/brw_bufmgr.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.c b/src/mesa/drivers/dri/i965/brw_bufmgr.c
index 8dda38d1262..fa7bf69a84e 100644
--- a/src/mesa/drivers/dri/i965/brw_bufmgr.c
+++ b/src/mesa/drivers/dri/i965/brw_bufmgr.c
@@ -826,12 +826,12 @@ brw_bo_map_unsynchronized(struct brw_context *brw, struct brw_bo *bo)
 int
 brw_bo_unmap(struct brw_bo *bo)
 {
-   struct brw_bufmgr *bufmgr = bo->bufmgr;
-   int ret = 0;
-
    if (bo == NULL)
       return 0;
 
+   struct brw_bufmgr *bufmgr = bo->bufmgr;
+   int ret = 0;
+
    pthread_mutex_lock(&bufmgr->lock);
 
    if (bo->map_count <= 0) {
-- 
2.12.2