Example to demonstrate race condition and how CriticalSectionLock API helps in resolving that.

Revision:
0:36e8acd8e607
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Oct 20 19:50:07 2017 +0000
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2016-2016, ARM Limited, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "rtos/Thread.h"
+#include "mbed.h"
+#include "rtos/rtos_idle.h"
+#include "platform/mbed_critical.h"
+
+#define  USE_CRITICAL_SECTION_LOCK      1   // Set 0 to see race condition
+// Note: Might require few runs to see race condition
+
+#define THREAD_CNT  8
+
+int32_t value = 100000;
+volatile int32_t count = 0;
+
+void increment(void) {
+    for (int i = 0; i < value; i++) {
+#if (USE_CRITICAL_SECTION_LOCK == 1)
+        CriticalSectionLock  lock;
+#endif
+        count += 1;
+    }
+}
+
+int get_count(void) {
+    if (count == (value * THREAD_CNT)) {
+        printf("No Race condition\n");
+    } else {
+        printf("Race condition\n");
+    }
+    return count;
+}
+
+int main()
+{
+    Thread counter_thread[THREAD_CNT];    
+
+    for (int i = 0; i < THREAD_CNT; i++) {
+        counter_thread[i].start(callback(increment));
+    }
+    
+    // Wait for the threads to finish
+    for (int i = 0; i < THREAD_CNT; i++) {
+        counter_thread[i].join();
+    }    
+    printf ("Counter = %d\n", get_count());
+}