freertos: Fixes deadlock in pthread_once for init_routines calling pthread_once

components/pthread/pthread.c

@@ -72,7 +72,7 @@ static int IRAM_ATTR pthread_mutex_lock_internal(esp_pthread_mutex_t *mux, TickT
 esp_err_t esp_pthread_init(void)
 {
     vListInitialise((List_t *)&s_threads_list);
-    s_once_mux = xSemaphoreCreateMutex();
+    s_once_mux = xSemaphoreCreateRecursiveMutex();
     if (s_once_mux == NULL) {
         return ESP_ERR_NO_MEM;
     }
@@ -377,7 +377,9 @@ int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
     TaskHandle_t cur_task = xTaskGetCurrentTaskHandle();
     // do not take mutex if OS is not running yet
     if (xTaskGetSchedulerState() == taskSCHEDULER_NOT_STARTED ||
-            !cur_task || xSemaphoreTake(s_once_mux, portMAX_DELAY) == pdTRUE)
+            // init_routine can call pthread_once for another objects, so use recursive mutex
+            // FIXME: behaviour is undefined if init_routine calls pthread_once for the same object in the current context
+            !cur_task || xSemaphoreTakeRecursive(s_once_mux, portMAX_DELAY) == pdTRUE)
     {
         if (!once_control->init_executed) {
             ESP_LOGV(TAG, "%s: call init_routine %p", __FUNCTION__, once_control);
@@ -385,7 +387,7 @@ int pthread_once(pthread_once_t *once_control, void (*init_routine)(void))
             once_control->init_executed = 1;
         }
         if (cur_task) {
-            xSemaphoreGive(s_once_mux);
+            xSemaphoreGiveRecursive(s_once_mux);
         }
     }
     else

components/pthread/test/test_pthread_cxx.cpp

@@ -2,6 +2,8 @@
 #include <sstream>
 #include <thread>
 #include <mutex>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
 #include "unity.h"
 
 #if __GTHREADS && __GTHREADS_CXX0X
@@ -61,7 +63,7 @@ static void thread_main()
     }
 }
 
-TEST_CASE("pthread CXX", "[pthread]")
+TEST_CASE("pthread C++", "[pthread]")
 {
     global_sp.reset(new int(1));
 
@@ -85,16 +87,32 @@ TEST_CASE("pthread CXX", "[pthread]")
     }
 }
 
-static void task_test_sandbox(void *ignore) {
+static void task_test_sandbox(void *arg)
+{
+    bool *running = (bool *)arg;
+
     ESP_LOGI(TAG, "About to create a string stream");
     std::stringstream ss;
     ESP_LOGI(TAG, "About to write to string stream");
     ss << "Hello World!";
+    ESP_LOGI(TAG, "About to extract from stringstream");
+    ESP_LOGI(TAG, "Text: %s", ss.str().c_str());
+
+    if (running) {
+        *running = false;
+        vTaskDelete(NULL);
+    }
 }
 
-TEST_CASE("pthread CXX 2", "[pthread]")
+TEST_CASE("pthread mix C/C++", "[pthread]")
 {
+    bool running = true;
+
     std::thread t1(task_test_sandbox, (void *)NULL);
+    xTaskCreatePinnedToCore((TaskFunction_t)&task_test_sandbox, "task_test_sandbox", 2048, &running, 5, NULL, 0);
+    while (running) {
+        vTaskDelay(1);
+    }
     if (t1.joinable()) {
         std::cout << "Join thread " << std::hex << t1.get_id() << std::endl;
         t1.join();