DEVICE_ATTR_RW 宏 解析

static DEVICE_ATTR_RW(test);

#define DEVICE_ATTR_RW(_name) \
struct device_attribute dev_attr_##_name = __ATTR_RW(_name)

struct device_attribute dev_attr_(test) = __ATTR_RW(test);

#define __ATTR_RW(_name) __ATTR(_name, (S_IWUSR | S_IRUGO), _name##_show, _name##_store)

struct device_attribute dev_attr_(test) = __ATTR(test, (S_IWUSR | S_IRUGO),test_show, test_store)

#define __ATTR(_name, _mode, _show, _store) {
.attr = {.name = __stringify(_name),
.mode = VERIFY_OCTAL_PERMISSIONS(_mode) },
.show = _show,
.store = _store,
}

struct device_attribute dev_attr_(test) = {
.attr = {.name = __stringify(test),
.mode = VERIFY_OCTAL_PERMISSIONS((S_IWUSR | S_IRUGO)) },
.show = test_show,
.store = test_store,
}

最终这个宏 static DEVICE_ATTR_RW(test); 生成以下：

struct device_attribute dev_attr_(test) = {
.attr = {.name = __stringify(test),
.mode = VERIFY_OCTAL_PERMISSIONS((S_IWUSR | S_IRUGO)) },
.show = test_show,
.store = test_store,
}