From cf4e9e5ce2d0a709eb7fd8b84fd70bf44a25bb8c Mon Sep 17 00:00:00 2001
From: Matthias Grundmann <grundmann.matthias@gmail.com>
Date: Wed, 10 May 2017 16:04:02 -0700
Subject: [PATCH] Update matrix.cpp

Fix race condition in getDefaultAllocator and setDefaultAllocator interaction / not threadsafe currently
---
 modules/core/src/matrix.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/modules/core/src/matrix.cpp b/modules/core/src/matrix.cpp
index 50a0856843..b02613e837 100644
--- a/modules/core/src/matrix.cpp
+++ b/modules/core/src/matrix.cpp
@@ -222,7 +222,7 @@ public:
 };
 namespace
 {
-    MatAllocator* g_matAllocator = NULL;
+    MatAllocator* volatile g_matAllocator = NULL;
 }
 
 
@@ -230,7 +230,11 @@ MatAllocator* Mat::getDefaultAllocator()
 {
     if (g_matAllocator == NULL)
     {
-        g_matAllocator = getStdAllocator();
+        cv::AutoLock lock(cv::getInitializationMutex());
+        if (g_matAllocator == NULL)
+        {
+            g_matAllocator = getStdAllocator();
+        }
     }
     return g_matAllocator;
 }