Function lwp_pid_get_locked

components/lwp/lwp_pid.c:219–263

* @brief Allocates a new PID while holding the PID management lock * * @return pid_t The newly allocated PID, or 0 if allocation failed * * @note This function attempts to allocate a new process ID (PID) from either: * 1. The free list (lwp_pid_free_head) if available * 2. The PID array (lwp_pid_ary) if within maximum limits * * It then searches for an unused PID in two r

 *       and current_pid is updated to the new PID.
 */
static pid_t lwp_pid_get_locked(void)
{
    struct lwp_avl_struct *p;
    pid_t pid = 0;

    p = lwp_pid_free_head;
    if (p)
    {
        lwp_pid_free_head = (struct lwp_avl_struct *)p->avl_right;
    }
    else if (lwp_pid_ary_alloced < RT_LWP_MAX_NR)
    {
        p = lwp_pid_ary + lwp_pid_ary_alloced;
        lwp_pid_ary_alloced++;
    }
    if (p)
    {
        int found_noused = 0;

        RT_ASSERT(p->data == RT_NULL);
        for (pid = current_pid + 1; pid < PID_MAX; pid++)
        {
            if (!lwp_avl_find(pid, lwp_pid_root))
            {
                found_noused = 1;
                break;
            }
        }
        if (!found_noused)
        {
            for (pid = 1; pid <= current_pid; pid++)
            {
                if (!lwp_avl_find(pid, lwp_pid_root))
                {
                    found_noused = 1;
                    break;
                }
            }
        }
        p->avl_key = pid;
        lwp_avl_insert(p, &lwp_pid_root);
        current_pid = pid;
    }
    return pid;
}

/**
 * @brief Release a PID back to the free list while holding the PID lock