core: simplify mutex initializer

core/include/mutex.h

@@ -44,14 +44,22 @@ typedef struct mutex_t {
 } mutex_t;
 
 /**
- * @brief Initializes a mutex object.
- *
- * @param[out] mutex    pre-allocated mutex structure, must not be NULL.
- *
- * @return  Always returns 1, always succeeds.
+ * @brief Static initializer for mutex_t.
+ * @details This initializer is preferrable to mutex_init().
  */
-int mutex_init(mutex_t *mutex);
+#define MUTEX_INIT { 0, QUEUE_NODE_INIT }
 
+/**
+ * @brief Initializes a mutex object.
+ * @details For intialization of variables use MUTEX_INIT instead.
+ *          Only use the function call for dynamically allocated mutexes.
+ * @param[out] mutex    pre-allocated mutex structure, must not be NULL.
+ */
+static inline void mutex_init(mutex_t *mutex)
+{
+    mutex_t empty_mutex = MUTEX_INIT;
+    *mutex = empty_mutex;
+}
 
 /**
  * @brief Tries to get a mutex, non-blocking.

core/include/queue.h

@@ -20,6 +20,7 @@
 #ifndef __QUEUE_H
 #define __QUEUE_H
 
+#include <stddef.h>
 #include <stdint.h>
 #include <inttypes.h>
 
@@ -41,6 +42,11 @@ typedef struct queue_node_t {
     uint32_t priority;          /**< queue node priority */
 } queue_node_t;
 
+/**
+ * @brief Static initializer for queue_node_t.
+ */
+#define QUEUE_NODE_INIT { NULL, 0, 0 }
+
 /**
  * @brief attach `new_obj` to the tail of the queue (identified
  * `root`)

core/mutex.c

@@ -35,15 +35,6 @@
 
 static void mutex_wait(struct mutex_t *mutex);
 
-void mutex_init(struct mutex_t *mutex)
-{
-    mutex->val = 0;
-
-    mutex->queue.priority = 0;
-    mutex->queue.data = 0;
-    mutex->queue.next = NULL;
-}
-
 int mutex_trylock(struct mutex_t *mutex)
 {
     DEBUG("%s: trylocking to get mutex. val: %u\n", sched_active_thread->name, mutex->val);