From ba93b3f8e403636b614a4a379f9421bc70dca84f Mon Sep 17 00:00:00 2001
From: Mathias Agopian <mathias@google.com>
Date: Thu, 1 Aug 2013 15:48:40 -0700
Subject: [PATCH] log an error when dequeueBuffer gets a NULL Fence

Bug: 9858745
Change-Id: If35d6a7d770bf0a42d55bc55880a9ddb721fcfd0
---
 libs/gui/BufferQueue.cpp            | 13 +++++++++----
 libs/gui/IGraphicBufferProducer.cpp | 11 ++++-------
 libs/gui/Surface.cpp                | 10 ++++++----
 libs/gui/SurfaceComposerClient.cpp  |  2 +-
 4 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/libs/gui/BufferQueue.cpp b/libs/gui/BufferQueue.cpp
index 45488ff8d..e20ac8679 100644
--- a/libs/gui/BufferQueue.cpp
+++ b/libs/gui/BufferQueue.cpp
@@ -406,6 +406,13 @@ status_t BufferQueue::dequeueBuffer(int *outBuf, sp<Fence>* outFence, bool async
             returnFlags |= IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION;
         }
 
+
+        if (CC_UNLIKELY(mSlots[buf].mFence == NULL)) {
+            ST_LOGE("dequeueBuffer: about to return a NULL fence from mSlot. "
+                    "buf=%d, w=%d, h=%d, format=%d",
+                    buf, buffer->width, buffer->height, buffer->format);
+        }
+
         dpy = mSlots[buf].mEglDisplay;
         eglFence = mSlots[buf].mEglFence;
         *outFence = mSlots[buf].mFence;
@@ -416,11 +423,9 @@ status_t BufferQueue::dequeueBuffer(int *outBuf, sp<Fence>* outFence, bool async
     if (returnFlags & IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION) {
         status_t error;
         sp<GraphicBuffer> graphicBuffer(
-                mGraphicBufferAlloc->createGraphicBuffer(
-                        w, h, format, usage, &error));
+                mGraphicBufferAlloc->createGraphicBuffer(w, h, format, usage, &error));
         if (graphicBuffer == 0) {
-            ST_LOGE("dequeueBuffer: SurfaceComposer::createGraphicBuffer "
-                    "failed");
+            ST_LOGE("dequeueBuffer: SurfaceComposer::createGraphicBuffer failed");
             return error;
         }
 
diff --git a/libs/gui/IGraphicBufferProducer.cpp b/libs/gui/IGraphicBufferProducer.cpp
index 48b28708f..e3d2a20df 100644
--- a/libs/gui/IGraphicBufferProducer.cpp
+++ b/libs/gui/IGraphicBufferProducer.cpp
@@ -94,13 +94,10 @@ public:
             return result;
         }
         *buf = reply.readInt32();
-        bool fenceWasWritten = reply.readInt32();
-        if (fenceWasWritten) {
-            // If the fence was written by the callee, then overwrite the
-            // caller's fence here.  If it wasn't written then don't touch the
-            // caller's fence.
+        bool nonNull = reply.readInt32();
+        if (nonNull) {
             *fence = new Fence();
-            reply.read(*(fence->get()));
+            reply.read(**fence);
         }
         result = reply.readInt32();
         return result;
@@ -209,7 +206,7 @@ status_t BnGraphicBufferProducer::onTransact(
             reply->writeInt32(buf);
             reply->writeInt32(fence != NULL);
             if (fence != NULL) {
-                reply->write(*fence.get());
+                reply->write(*fence);
             }
             reply->writeInt32(result);
             return NO_ERROR;
diff --git a/libs/gui/Surface.cpp b/libs/gui/Surface.cpp
index 998ea8ac8..fdb7d3d93 100644
--- a/libs/gui/Surface.cpp
+++ b/libs/gui/Surface.cpp
@@ -175,8 +175,7 @@ int Surface::setSwapInterval(int interval) {
     return NO_ERROR;
 }
 
-int Surface::dequeueBuffer(android_native_buffer_t** buffer,
-        int* fenceFd) {
+int Surface::dequeueBuffer(android_native_buffer_t** buffer, int* fenceFd) {
     ATRACE_CALL();
     ALOGV("Surface::dequeueBuffer");
     Mutex::Autolock lock(mMutex);
@@ -193,6 +192,10 @@ int Surface::dequeueBuffer(android_native_buffer_t** buffer,
         return result;
     }
     sp<GraphicBuffer>& gbuf(mSlots[buf].buffer);
+
+    // this should never happen
+    ALOGE_IF(fence == NULL, "Surface::dequeueBuffer: received null Fence! buf=%d", buf);
+
     if (result & IGraphicBufferProducer::RELEASE_ALL_BUFFERS) {
         freeAllBuffers();
     }
@@ -200,8 +203,7 @@ int Surface::dequeueBuffer(android_native_buffer_t** buffer,
     if ((result & IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION) || gbuf == 0) {
         result = mGraphicBufferProducer->requestBuffer(buf, &gbuf);
         if (result != NO_ERROR) {
-            ALOGE("dequeueBuffer: IGraphicBufferProducer::requestBuffer failed: %d",
-                    result);
+            ALOGE("dequeueBuffer: IGraphicBufferProducer::requestBuffer failed: %d", result);
             return result;
         }
     }
diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index 94f21b645..bad413883 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -653,7 +653,7 @@ status_t ScreenshotClient::update(const sp<IBinder>& display,
         mHaveBuffer = false;
     }
 
-    status_t err = s->captureScreen(display,cpuConsumer->getBufferQueue(),
+    status_t err = s->captureScreen(display, cpuConsumer->getBufferQueue(),
             reqWidth, reqHeight, minLayerZ, maxLayerZ, true);
 
     if (err == NO_ERROR) {