From 4f328d8388980604330f0ea1d28ae5734983d648 Mon Sep 17 00:00:00 2001
From: peng xiao <hisenxpress@gmail.com>
Date: Fri, 12 Apr 2013 15:43:33 +0800
Subject: [PATCH] Fix a potential bug of ocl::CannyBuf.

The program would crash if release is called twice.
---
 modules/ocl/src/canny.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/modules/ocl/src/canny.cpp b/modules/ocl/src/canny.cpp
index 4219af1ca2..e06d29904e 100644
--- a/modules/ocl/src/canny.cpp
+++ b/modules/ocl/src/canny.cpp
@@ -112,7 +112,11 @@ void cv::ocl::CannyBuf::release()
     mapBuf.release();
     trackBuf1.release();
     trackBuf2.release();
-    openCLFree(counter);
+    if(counter)
+    {
+        openCLFree(counter);
+        counter = NULL;
+    }
 }
 
 namespace cv