Change return value of mutex and semaphore handling functions

Changed mutex lock/unlock and semaphore take/give functions to return
an int value instead of void. In addition changed FreeRTOS and
message_handler applications (also FreeRTOS-based) to ignore failure
of xSemaphoreGive on binary semaphores, as it does not affect the
correctness of such applications.

Change-Id: I023c62dc8971488107679f6dd7a5967dec0380a8

1 files changed, 33 insertions, 8 deletions

diff --git a/applications/message_handler/main.cpp b/applications/message_handler/main.cpp
index d478ae6..dde5dc5 100644
--- a/applications/message_handler/main.cpp
+++ b/applications/message_handler/main.cpp
@@ -96,28 +96,53 @@ void *ethosu_mutex_create(void) {
     return xSemaphoreCreateMutex();
 }
 
-void ethosu_mutex_lock(void *mutex) {
+int ethosu_mutex_lock(void *mutex) {
     SemaphoreHandle_t handle = reinterpret_cast<SemaphoreHandle_t>(mutex);
-    xSemaphoreTake(handle, portMAX_DELAY);
+    if (xSemaphoreTake(handle, portMAX_DELAY) != pdTRUE) {
+        printf("Error: Failed to lock mutex.\n");
+        return -1;
+    }
+    return 0;
 }
 
-void ethosu_mutex_unlock(void *mutex) {
+int ethosu_mutex_unlock(void *mutex) {
     SemaphoreHandle_t handle = reinterpret_cast<SemaphoreHandle_t>(mutex);
-    xSemaphoreGive(handle);
+    if (xSemaphoreGive(handle) != pdTRUE) {
+        printf("Error: Failed to unlock mutex.\n");
+        return -1;
+    }
+    return 0;
 }
 
 void *ethosu_semaphore_create(void) {
     return xSemaphoreCreateBinary();
 }
 
-void ethosu_semaphore_take(void *sem) {
+int ethosu_semaphore_take(void *sem) {
     SemaphoreHandle_t handle = reinterpret_cast<SemaphoreHandle_t>(sem);
-    xSemaphoreTake(handle, portMAX_DELAY);
+    if (xSemaphoreTake(handle, portMAX_DELAY) != pdTRUE) {
+        printf("Error: Failed to take semaphore.\n");
+        return -1;
+    }
+    return 0;
 }
 
-void ethosu_semaphore_give(void *sem) {
+int ethosu_semaphore_give(void *sem) {
     SemaphoreHandle_t handle = reinterpret_cast<SemaphoreHandle_t>(sem);
-    xSemaphoreGiveFromISR(handle, NULL);
+    if (xPortIsInsideInterrupt()) {
+        if (xSemaphoreGiveFromISR(handle, NULL) != pdTRUE) {
+            printf("Error: Failed to give semaphore from ISR.\n");
+            return -1;
+        }
+    } else {
+        /* A FreeRTOS binary semaphore is fundamentally a queue that can only hold one item. If the queue is full,
+         * xSemaphoreGive will return a pdFALSE value. Ignoring the return value in here, as a semaphore give failure
+         * does not affect the application correctness. */
+        if (xSemaphoreGive(handle) != pdTRUE) {
+            // do nothing
+        }
+    }
+    return 0;
 }
 }