//device_create的定义如下

struct device *device_create(struct class *class, struct device *parent,

                 dev_t devt, void *drvdata, const char *fmt, ...)

{

    va_list vargs;

    struct device *dev;

    va_start(vargs, fmt);

    dev = device_create_vargs(class, parent, devt, drvdata, fmt, vargs);

    va_end(vargs);

    return dev;

}

//device_create_vargs的定义如下

struct device *device_create_vargs(struct class *class, struct device *parent,

                   dev_t devt, void *drvdata, const char *fmt,

                   va_list args)

{

    struct device *dev = NULL;

    int retval = -ENODEV;

    if (class == NULL || IS_ERR(class))

        goto error;

    dev = kzalloc(sizeof(*dev), GFP_KERNEL);

    if (!dev) {

        retval = -ENOMEM;

        goto error;

    }

    dev->devt = devt;

    dev->class = class;

    dev->parent = parent;

    dev->release = device_create_release;

    dev_set_drvdata(dev, drvdata);

    retval = kobject_set_name_vargs(&dev->kobj, fmt, args);

    if (retval)

        goto error;

    retval = device_register(dev);

    if (retval)

        goto error;

    return dev;

error:

    put_device(dev);

    return ERR_PTR(retval);

}