Function rt_mutex_drop_thread

src/ipc.c:1079–1141

* @brief drop a thread from the suspend list of mutex * * @param mutex is a pointer to a mutex object. * @param thread is the thread should be dropped from mutex. */

 * @param thread is the thread should be dropped from mutex.
 */
void rt_mutex_drop_thread(rt_mutex_t mutex, rt_thread_t thread)
{
    rt_uint8_t priority;
    rt_bool_t need_update = RT_FALSE;
    rt_sched_lock_level_t slvl;

    /* parameter check */
    RT_DEBUG_IN_THREAD_CONTEXT;
    RT_ASSERT(mutex != RT_NULL);
    RT_ASSERT(thread != RT_NULL);

    rt_spin_lock(&(mutex->spinlock));

    RT_ASSERT(thread->pending_object == &mutex->parent.parent);

    rt_sched_lock(&slvl);

    /* detach from suspended list */
    rt_list_remove(&RT_THREAD_LIST_NODE(thread));

    /**
     * Should change the priority of mutex owner thread
     * Note: After current thread is detached from mutex pending list, there is
     *       a chance that the mutex owner has been released the mutex. Which
     *       means mutex->owner can be NULL at this point. If that happened,
     *       it had already reset its priority. So it's okay to skip
     */
    if (mutex->owner && rt_sched_thread_get_curr_prio(mutex->owner) ==
                            rt_sched_thread_get_curr_prio(thread))
    {
        need_update = RT_TRUE;
    }

    /* update the priority of mutex */
    if (!rt_list_isempty(&mutex->parent.suspend_thread))
    {
        /* more thread suspended in the list */
        struct rt_thread *th;

        th = RT_THREAD_LIST_NODE_ENTRY(mutex->parent.suspend_thread.next);
        /* update the priority of mutex */
        mutex->priority = rt_sched_thread_get_curr_prio(th);
    }
    else
    {
        /* set mutex priority to maximal priority */
        mutex->priority = 0xff;
    }

    /* try to change the priority of mutex owner thread */
    if (need_update)
    {
        /* get the maximal priority of mutex in thread */
        priority = _thread_get_mutex_priority(mutex->owner);
        if (priority != rt_sched_thread_get_curr_prio(mutex->owner))
        {
            _thread_update_priority(mutex->owner, priority, RT_UNINTERRUPTIBLE);
        }