drm_hwcomposer: Reference count NvImporter buffers

Instead of directly freeing buffers from the NvImporter
release callback, use reference counting to ensure that
we:
    (a) don't free the buffer while NvGralloc is still using it
    (b) don't free the buffer while HWC is still using it

Before this patch, we weren't satisifying (b). This would
cause us to free a buffer before and while it was on the
screen.

Change-Id: I6bbc541c72df4d5f12a8734de2f2e68168b73a07
Signed-off-by: Sean Paul <seanpaul@chromium.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/nvimporter.h b/nvimporter.h
index e3bdd1c..a07f577 100644
--- a/nvimporter.h
+++ b/nvimporter.h
@@ -20,6 +20,8 @@
 #include "drmresources.h"
 #include "importer.h"
 
+#include <stdatomic.h>
+
 #include <hardware/gralloc.h>
 
 namespace android {
@@ -38,9 +40,10 @@ class NvImporter : public Importer {
   typedef struct NvBuffer {
     NvImporter *importer;
     hwc_drm_bo_t bo;
+    atomic_int ref;
   } NvBuffer_t;
 
-  static void ReleaseBufferCallback(void *nv_buffer);
+  static void NvGrallocRelease(void *nv_buffer);
   void ReleaseBufferImpl(hwc_drm_bo_t *bo);
 
   NvBuffer_t *GrallocGetNvBuffer(buffer_handle_t handle);