Function rt_sem_release

src/ipc.c:696–742

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

 *           If the return value is any other values, it means that the semaphore release failed.
 */
rt_err_t rt_sem_release(rt_sem_t sem)
{
    rt_base_t level;
    rt_bool_t need_schedule;

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

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

    need_schedule = RT_FALSE;

    level = rt_spin_lock_irqsave(&(sem->spinlock));

    LOG_D("thread %s releases sem:%s, which value is: %d",
          rt_thread_self()->parent.name,
          sem->parent.parent.name,
          sem->value);

    if (!rt_list_isempty(&sem->parent.suspend_thread))
    {
        /* resume the suspended thread */
        rt_susp_list_dequeue(&(sem->parent.suspend_thread), RT_EOK);
        need_schedule = RT_TRUE;
    }
    else
    {
        if(sem->value < sem->max_value)
        {
            sem->value ++; /* increase value */
        }
        else
        {
            rt_spin_unlock_irqrestore(&(sem->spinlock), level);
            return -RT_EFULL; /* value overflowed */
        }
    }

    rt_spin_unlock_irqrestore(&(sem->spinlock), level);

    /* resume a thread, re-schedule */
    if (need_schedule == RT_TRUE)
        rt_schedule();

    return RT_EOK;
}
RTM_EXPORT(rt_sem_release);