本文主要是介绍Linux设备模型-5-kobj_attribute练习，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
在上一篇文章中，我们分析了怎样创建自定义对象，对象类型及自定义对象的属性等。下面就是其实现的全部代码：
#include <linux/device.h> /* 包含内核对象模型的数据结构的定义及辅助函数 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h> /* 包含 kcalloc(),kzalloc()函数等 */MODULE_AUTHOR("Tupelo Shen");
MODULE_LICENSE("Dual BSD/GPL");/** 定义container_of的简便方法*/
#define to_my_kobj(data) container_of(data, struct my_kobj, kobj)/** 自定义内核对象结构*/
struct my_kobj {int val;struct kobject kobj;
};// 自定义属性
struct my_attribute {struct attribute attr;ssize_t (*show)(struct my_kobj *obj, struct my_attribute *attr, char *buf);ssize_t (*store)(struct my_kobj *obj, struct my_attribute *attr,const char *buf, size_t count);
};/* * 分别为name和val两个属性定义自己的show/store函数。* name这个属性是只读的，只要为它定义show即可*/
ssize_t name_show(struct my_kobj *obj, struct my_attribute *attr, char *buffer)
{return sprintf(buffer, "%s\n", kobject_name(&obj->kobj));
}
ssize_t val_show(struct my_kobj *obj, struct my_attribute *attr, char *buffer)
{return sprintf(buffer, "%d\n", obj->val);
}
ssize_t val_store(struct my_kobj *obj, struct my_attribute *attr,const char *buffer, size_t size)
{sscanf(buffer, "%d", &obj->val);return size;
}/** 定义name和val属性*/
struct my_attribute name_attribute = __ATTR(name, 0444, name_show, NULL);
struct my_attribute val_attribute = __ATTR(val, 0666, val_show, val_store);struct attribute *my_attrs[] = {&name_attribute.attr,&val_attribute.attr,NULL,
};/** 用户空间调用读写函数时的属性显示和存储函数*/
static ssize_t my_attr_show(struct kobject *kobj, struct attribute *attr, char *buffer)
{struct my_attribute *my_attr;ssize_t ret = -EIO;my_attr = container_of(attr, struct my_attribute, attr);if(my_attr->show)ret = my_attr->show(container_of(kobj,struct my_kobj, kobj), my_attr, buffer);return ret;
}static ssize_t my_attr_store(struct kobject *kobj, struct attribute *attr, const char *buffer, size_t size)
{struct my_attribute *my_attr;ssize_t ret = -EIO;my_attr = container_of(attr, struct my_attribute, attr);if(my_attr->store)ret = my_attr->store(container_of(kobj, struct my_kobj, kobj), my_attr, buffer, size);return ret;
}struct sysfs_ops my_sysfsops = {.show = my_attr_show,.store = my_attr_store,
};struct attribute_group my_group = {.name = "mygroup",.attrs = my_attrs,
}; /** 定义两个内核对象，它们的层次结构如下： ** mykobj/* |-- mygroup* | |-- name* | `-- val* |-- name* `-- val*/
struct my_kobj *obj;
struct kobj_type my_type;void obj_release(struct kobject *kobj)
{struct my_kobj *my_kobj_free = to_my_kobj(kobj);printk(KERN_INFO "my_kobj_release\n");kfree(my_kobj_free);
}/** 初始化内核对象，完成创建并添加*/
static int __init my_kobj_init(void)
{int retval = 0;printk(KERN_INFO "mykobj_init\n");obj = (struct my_kobj *)kzalloc(sizeof(struct my_kobj), GFP_KERNEL);if (!obj) {return -ENOMEM;}obj->val = 1; my_type.release = obj_release;// my_type.default_attrs = my_attrs;my_type.sysfs_ops = &my_sysfsops;// 父节点-在这儿为/sys/kernel/kobject_init_and_add(&obj->kobj, &my_type, kernel_kobj, "mykobj");// 创建多个属性文件name和valretval = sysfs_create_files(&obj->kobj,(const struct attribute **)my_attrs);if (retval){printk(KERN_INFO "create obj attribute failed!\n");kobject_put(&obj->kobj);return retval;}// 对于一个给定的对象，创建属性组retval = sysfs_create_group(&obj->kobj, &my_group);if (retval) {printk(KERN_INFO "create obj attribute group failed!\n");}return retval;
}static void __exit my_kobj_exit(void)
{printk(KERN_INFO "mykobj_exit\n");kobject_del(&obj->kobj);kobject_put(&obj->kobj);return;
}module_init(my_kobj_init);
module_exit(my_kobj_exit);
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