camera: prevent possible deadlock scenario

Hold scope of returnFrame lock for just the calculation
of refCount. Otherwise, we could have a scenario where
endImageCapture and stopRecording could cause a deadlock
competing for mReturnFrameLock and mLock. Issue arises
mainly because endImageCapture is signalled from
fillThisBuffer which stopRecording will need to get into.

Make sure mEventQ has a message before calling get() since
read on the pipe will block with notifyEvent holding mLock.

Change-Id: I3a125711632fa311fd794e300cd5008321a84c40
Signed-off-by: Tyler Luu <tluu@ti.com>

2 files changed, 7 insertions, 4 deletions

diff --git a/camera/AppCallbackNotifier.cpp b/camera/AppCallbackNotifier.cpp
index 77b0556..aa41141 100644
--- a/camera/AppCallbackNotifier.cpp
+++ b/camera/AppCallbackNotifier.cpp
@@ -311,8 +311,12 @@ void AppCallbackNotifier::notifyEvent()
     TIUTILS::Message msg;
     LOG_FUNCTION_NAME;
     {
-    Mutex::Autolock lock(mLock);
-    mEventQ.get(&msg);
+        Mutex::Autolock lock(mLock);
+        if(!mEventQ.isEmpty()) {
+            mEventQ.get(&msg);
+        } else {
+            return;
+        }
     }
     bool ret = true;
     CameraHalEvent *evt = NULL;
diff --git a/camera/BaseCameraAdapter.cpp b/camera/BaseCameraAdapter.cpp
index 69291af..ec75232 100644
--- a/camera/BaseCameraAdapter.cpp
+++ b/camera/BaseCameraAdapter.cpp
@@ -258,8 +258,6 @@ void BaseCameraAdapter::returnFrame(void* frameBuf, CameraFrame::FrameType frame
     size_t subscriberCount = 0;
     int refCount = -1;
 
-    Mutex::Autolock lock(mReturnFrameLock);
-
     if ( NULL == frameBuf )
         {
         CAMHAL_LOGEA("Invalid frameBuf");
@@ -268,6 +266,7 @@ void BaseCameraAdapter::returnFrame(void* frameBuf, CameraFrame::FrameType frame
 
     if ( NO_ERROR == res)
         {
+        Mutex::Autolock lock(mReturnFrameLock);
 
         refCount = getFrameRefCount(frameBuf,  frameType);