[PATCH 3/4] intel: make bo_unreference() thread safe

[Lionel Landwerlin]

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
---
 intel/intel_bufmgr_gem.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index 1e2dd77..bf6745d 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -1157,7 +1157,8 @@ static void drm_intel_gem_bo_unreference(drm_intel_bo *bo)
 	drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *) bo;
 
 	assert(atomic_read(&bo_gem->refcount) > 0);
-	if (atomic_dec_and_test(&bo_gem->refcount)) {
+
+	if (atomic_add_unless(&bo_gem->refcount, -1, 1)) {
 		drm_intel_bufmgr_gem *bufmgr_gem =
 		    (drm_intel_bufmgr_gem *) bo->bufmgr;
 		struct timespec time;
@@ -1165,8 +1166,12 @@ static void drm_intel_gem_bo_unreference(drm_intel_bo *bo)
 		clock_gettime(CLOCK_MONOTONIC, &time);
 
 		pthread_mutex_lock(&bufmgr_gem->lock);
-		drm_intel_gem_bo_unreference_final(bo, time.tv_sec);
-		drm_intel_gem_cleanup_bo_cache(bufmgr_gem, time.tv_sec);
+
+		if (atomic_dec_and_test(&bo_gem->refcount)) {
+			drm_intel_gem_bo_unreference_final(bo, time.tv_sec);
+			drm_intel_gem_cleanup_bo_cache(bufmgr_gem, time.tv_sec);
+		}
+
 		pthread_mutex_unlock(&bufmgr_gem->lock);
 	}
 }
-- 
2.0.1