Function _rt_mutex_take

src/ipc.c:1327–1537

* @brief This function will take a mutex, if the mutex is unavailable, the thread shall wait for * the mutex up to a specified time. * * @note When this function is called, the count value of the mutex->value will decrease 1 until it is equal to 0. * When the mutex->value is 0, it means that the mutex is unavailable. At this time, it will suspend the * thr

 * @warning  This function can ONLY be called in the thread context. It MUST NOT BE called in interrupt context.
 */
static rt_err_t _rt_mutex_take(rt_mutex_t mutex, rt_int32_t timeout, int suspend_flag)
{
    struct rt_thread *thread;
    rt_err_t ret;

    /* this function must not be used in interrupt even if time = 0 */
    /* current context checking */
    RT_DEBUG_SCHEDULER_AVAILABLE(RT_TRUE);

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

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

    rt_spin_lock(&(mutex->spinlock));

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

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

    /* reset thread error */
    thread->error = RT_EOK;

    if (mutex->owner == thread)
    {
        if (mutex->hold < RT_MUTEX_HOLD_MAX)
        {
            /* it's the same thread */
            mutex->hold ++;
        }
        else
        {
            rt_spin_unlock(&(mutex->spinlock));
            return -RT_EFULL; /* value overflowed */
        }
    }
    else
    {
        /* whether the mutex has owner thread. */
        if (mutex->owner == RT_NULL)
        {
            /* set mutex owner and original priority */
            mutex->owner    = thread;
            mutex->priority = 0xff;
            mutex->hold     = 1;

            if (mutex->ceiling_priority != 0xFF)
            {
                /* set the priority of thread to the ceiling priority */
                if (mutex->ceiling_priority < rt_sched_thread_get_curr_prio(mutex->owner))
                    _thread_update_priority(mutex->owner, mutex->ceiling_priority, suspend_flag);
            }

            /* insert mutex to thread's taken object list */
            rt_list_insert_after(&thread->taken_object_list, &mutex->taken_list);