Fix Thread::start() and general_block_device test's thread allocation/deallocation

rtos/include/rtos/Thread.h

@@ -131,7 +131,8 @@ class Thread : private mbed::NonCopyable<Thread> {
 
     /** Starts a thread executing the specified function.
       @param   task           function to be executed by this thread.
-      @return  status code that indicates the execution status of the function.
+      @return  status code that indicates the execution status of the function,
+               or osErrorNoMemory if stack allocation failed.
       @note a thread can only be started once
 
       @note You cannot call this function ISR context.

rtos/source/Thread.cpp

@@ -81,8 +81,11 @@ osStatus Thread::start(mbed::Callback<void()> task)
     }
 
     if (_attr.stack_mem == nullptr) {
-        _attr.stack_mem = new uint32_t[_attr.stack_size / sizeof(uint32_t)];
-        MBED_ASSERT(_attr.stack_mem != nullptr);
+        _attr.stack_mem = new (std::nothrow) uint32_t[_attr.stack_size / sizeof(uint32_t)];
+        if (_attr.stack_mem == nullptr) {
+            _mutex.unlock();
+            return osErrorNoMemory;
+        }
     }
 
     //Fill the stack with a magic word for maximum usage checking

storage/blockdevice/tests/TESTS/blockdevice/general_block_device/main.cpp

@@ -421,40 +421,35 @@ void test_multi_threads()
 
     osStatus threadStatus;
     int i_ind, j_ind;
-    char *dummy;
 
-    rtos::Thread **bd_thread = new (std::nothrow) rtos::Thread*[TEST_NUM_OF_THREADS];
-    TEST_SKIP_UNLESS_MESSAGE((*bd_thread) != NULL, "not enough heap to run test.");
-    memset(bd_thread, 0, TEST_NUM_OF_THREADS * sizeof(rtos::Thread *));
+    rtos::Thread *bd_thread[TEST_NUM_OF_THREADS] {};
 
     for (i_ind = 0; i_ind < TEST_NUM_OF_THREADS; i_ind++) {
 
         bd_thread[i_ind] = new (std::nothrow) rtos::Thread((osPriority_t)((int)osPriorityNormal), TEST_THREAD_STACK_SIZE);
-        dummy = new (std::nothrow) char[TEST_THREAD_STACK_SIZE];
 
-        if (!bd_thread[i_ind] || !dummy) {
-            utest_printf("Not enough heap to run Thread  %d !\n", i_ind + 1);
+        if (!bd_thread[i_ind]) {
+            utest_printf("Not enough heap to create Thread %d\n", i_ind + 1);
             break;
         }
-        delete[] dummy;
 
         threadStatus = bd_thread[i_ind]->start(callback(test_thread_job));
-        if (threadStatus != 0) {
-            utest_printf("Thread %d Start Failed!\n", i_ind + 1);
+        if (threadStatus == osErrorNoMemory) {
+            utest_printf("Not enough heap to start Thread %d\n", i_ind + 1);
+        } else if (threadStatus != osOK) {
+            utest_printf("Thread %d failed to start: %d\n", i_ind + 1, threadStatus);
             break;
         }
     }
 
+    // Join threads that successfully started
     for (j_ind = 0; j_ind < i_ind; j_ind++) {
         bd_thread[j_ind]->join();
     }
 
-    if (bd_thread) {
-        for (j_ind = 0; j_ind < i_ind; j_ind++) {
-            delete bd_thread[j_ind];
-        }
-
-        delete[] bd_thread;
+    // Delete all threads, even those that failed to start
+    for (j_ind = 0; j_ind < TEST_NUM_OF_THREADS; j_ind++) {
+        delete bd_thread[j_ind];
     }
 }
 #endif