Linux 内核文件系统与设备操作流程分析

Linux 内核文件系统与设备操作流程分析(12)
                //
                // 如果此字符设备结构无效，则从设备对象管理中查找
                //
        kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
        if (!kobj)
            return -ENXIO;
        new = container_of(kobj, struct cdev, kobj);
        spin_lock(&cdev_lock);

                //
                // 再次尝试获得正确的字符设备结构
                //
        p = inode->i_cdev;
        if (!p) {
            inode->i_cdev = p = new;
            inode->i_cindex = idx;
            list_add(&inode->i_devices, &p->list);
            new = NULL;
                //
                // 使用 cdev_get() 函数判断相应设备结构的内核设备对象是否
                // 有效
                //