From d3a9985f101aa45972eafe943e68eef70efc5e3d Mon Sep 17 00:00:00 2001
From: Siu Chi Chan <siuchi.chan@amd.com>
Date: Sat, 2 Jun 2018 17:55:37 -0400
Subject: [PATCH 1/2] callback handler: don't need to wait for the thread to
 become ready

---
 src/hip_stream.cpp | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/src/hip_stream.cpp b/src/hip_stream.cpp
index d9c227b6ac..4170e33d63 100644
--- a/src/hip_stream.cpp
+++ b/src/hip_stream.cpp
@@ -201,14 +201,5 @@ hipError_t hipStreamAddCallback(hipStream_t stream, hipStreamCallback_t callback
     ihipStreamCallback_t* cb = new ihipStreamCallback_t(stream, callback, userData);
     std::thread(ihipStreamCallbackHandler, cb).detach();
 
-    // Wait for thread to be ready
-    cb->_mtx.lock();
-    while (cb->_ready != true) {
-        cb->_mtx.unlock();
-        std::this_thread::sleep_for(std::chrono::milliseconds(10));
-        cb->_mtx.lock();
-    }
-    cb->_mtx.unlock();
-
     return ihipLogStatus(e);
 }

From a1f3b587fb6c29b3217e2d3baac00448dc208f83 Mon Sep 17 00:00:00 2001
From: Siu Chi Chan <siuchi.chan@amd.com>
Date: Mon, 4 Jun 2018 17:29:04 -0400
Subject: [PATCH 2/2] remove the _ready flag in ihipStreamCallback_t and the
 mutex that protects it.

---
 src/hip_hcc.cpp        | 4 ----
 src/hip_hcc_internal.h | 3 ---
 2 files changed, 7 deletions(-)

diff --git a/src/hip_hcc.cpp b/src/hip_hcc.cpp
index 9856dc1905..538a9039bf 100644
--- a/src/hip_hcc.cpp
+++ b/src/hip_hcc.cpp
@@ -1445,10 +1445,6 @@ hipError_t ihipStreamSynchronize(hipStream_t stream) {
 void ihipStreamCallbackHandler(ihipStreamCallback_t* cb) {
     hipError_t e = hipSuccess;
 
-    // Notify hipStreamAddCallback that callback handler thread is active
-    std::lock_guard<std::mutex> guard(cb->_mtx);
-    cb->_ready = true;
-
     // Synchronize stream
     tprintf(DB_SYNC, "ihipStreamCallbackHandler wait on stream %s\n",
             ToString(cb->_stream).c_str());
diff --git a/src/hip_hcc_internal.h b/src/hip_hcc_internal.h
index ce8041ef63..4008df1574 100644
--- a/src/hip_hcc_internal.h
+++ b/src/hip_hcc_internal.h
@@ -620,13 +620,10 @@ class ihipStreamCallback_t {
    public:
     ihipStreamCallback_t(hipStream_t stream, hipStreamCallback_t callback, void* userData)
         : _stream(stream), _callback(callback), _userData(userData) {
-        _ready = false;
     };
     hipStream_t _stream;
     hipStreamCallback_t _callback;
     void* _userData;
-    std::mutex _mtx;
-    bool _ready;
 };