Function rt_mutex_release

src/ipc.c:1591–1717

* @brief This function will release a mutex. If there is thread suspended on the mutex, the thread will be resumed. * * @note If there are threads suspended on this mutex, the first thread in the list of this mutex object * will be resumed, and a thread scheduling (rt_schedule) will be executed. * If no threads are suspended on this mutex, the count value mutex->valu

 *           If the return value is any other values, it means that the mutex release failed.
 */
rt_err_t rt_mutex_release(rt_mutex_t mutex)
{
    rt_sched_lock_level_t slvl;
    struct rt_thread *thread;
    rt_bool_t need_schedule;

    /* parameter check */
    RT_ASSERT(mutex != RT_NULL);
    RT_ASSERT(rt_object_get_type(&mutex->parent.parent) == RT_Object_Class_Mutex);

    need_schedule = RT_FALSE;

    /* only thread could release mutex because we need test the ownership */
    RT_DEBUG_IN_THREAD_CONTEXT;

    /* get current thread */
    thread = rt_thread_self();

    rt_spin_lock(&(mutex->spinlock));

    LOG_D("mutex_release:current thread %s, hold: %d",
          thread->parent.name, mutex->hold);

    RT_OBJECT_HOOK_CALL(rt_object_put_hook, (&(mutex->parent.parent)));

    /* mutex only can be released by owner */
    if (thread != mutex->owner)
    {
        thread->error = -RT_ERROR;
        rt_spin_unlock(&(mutex->spinlock));

        return -RT_ERROR;
    }

    /* decrease hold */
    mutex->hold --;
    /* if no hold */
    if (mutex->hold == 0)
    {
        rt_sched_lock(&slvl);

        /* remove mutex from thread's taken list */
        rt_list_remove(&mutex->taken_list);

        /* whether change the thread priority */
        need_schedule = _check_and_update_prio(thread, mutex);

        /* wakeup suspended thread */
        if (!rt_list_isempty(&mutex->parent.suspend_thread))
        {
            struct rt_thread *next_thread;
            do
            {
                /* get the first suspended thread */
                next_thread = RT_THREAD_LIST_NODE_ENTRY(mutex->parent.suspend_thread.next);

                RT_ASSERT(rt_sched_thread_is_suspended(next_thread));