Refactor NimBLEUtils::taskWait to check notification value before blocking.

Instead of incrementing the notificatin value via `xTaskNotifyGive` this will now set a specific bit in the task notification value
which will be tested before blocking a task. This will prevent a task from blocking indefinitely if the event that calls `taskRelease`
occurs before entering the blocked state.

* Adds a config setting for the bit to set in the task notification value.

Author: h2zero

src/NimBLEUtils.cpp

@@ -27,6 +27,10 @@
 # include <stdlib.h>
 # include <climits>
 
+# if defined INC_FREERTOS_H
+constexpr uint32_t TASK_BLOCK_BIT = (1 << CONFIG_NIMBLE_CPP_FREERTOS_TASK_BLOCK_BIT);
+# endif
+
 static const char* LOG_TAG = "NimBLEUtils";
 
 /**
@@ -44,12 +48,14 @@ bool NimBLEUtils::taskWait(const NimBLETaskData& taskData, uint32_t timeout) {
     }
 
 # if defined INC_FREERTOS_H
+    uint32_t notificationValue;
+    xTaskNotifyWait(0, TASK_BLOCK_BIT, &notificationValue, 0);
+    if (notificationValue & TASK_BLOCK_BIT) {
+        return true;
+    }
+
     taskData.m_pHandle = xTaskGetCurrentTaskHandle();
-#  ifdef ulTaskNotifyValueClear
-    // Clear the task notification value to ensure we block
-    ulTaskNotifyValueClear(static_cast<TaskHandle_t>(taskData.m_pHandle), ULONG_MAX);
-#  endif
-    return ulTaskNotifyTake(pdTRUE, ticks) == pdTRUE;
+    return xTaskNotifyWait(0, TASK_BLOCK_BIT, nullptr, ticks) == pdTRUE;
 
 # else
     ble_npl_sem     sem;
@@ -73,10 +79,10 @@ bool NimBLEUtils::taskWait(const NimBLETaskData& taskData, uint32_t timeout) {
  * @param [in] flags A return value to set in the task data structure.
  */
 void NimBLEUtils::taskRelease(const NimBLETaskData& taskData, int flags) {
+    taskData.m_flags = flags;
     if (taskData.m_pHandle != nullptr) {
-        taskData.m_flags = flags;
 # if defined INC_FREERTOS_H
-        xTaskNotifyGive(static_cast<TaskHandle_t>(taskData.m_pHandle));
+        xTaskNotify(static_cast<TaskHandle_t>(taskData.m_pHandle), TASK_BLOCK_BIT, eSetBits);
 # else
         ble_npl_sem_release(static_cast<ble_npl_sem*>(taskData.m_pHandle));
 # endif

src/nimconfig.h

@@ -148,6 +148,13 @@
  */
 // #define CONFIG_NIMBLE_STACK_USE_MEM_POOLS 1
 
+/**
+ * @brief Un-comment to change the bit used to block tasks during BLE operations
+ * that call NimBLEUtils::taskWait. This should be different than any other
+ * task notification flag used in the system.
+ */
+// #define CONFIG_NIMBLE_CPP_FREERTOS_TASK_BLOCK_BIT 31
+
 /**********************************
  End Arduino user-config
 **********************************/
@@ -350,6 +357,10 @@
 #define CONFIG_NIMBLE_CPP_DEBUG_ASSERT_ENABLED 0
 #endif
 
+#ifndef CONFIG_NIMBLE_CPP_FREERTOS_TASK_BLOCK_BIT
+#define CONFIG_NIMBLE_CPP_FREERTOS_TASK_BLOCK_BIT 31
+#endif
+
 #if CONFIG_NIMBLE_CPP_DEBUG_ASSERT_ENABLED && !defined NDEBUG
 void nimble_cpp_assert(const char *file, unsigned line) __attribute((weak, noreturn));
 # define NIMBLE_ATT_VAL_FILE  (__builtin_strrchr(__FILE__, '/') ? \