[root@tiny4412 mnt]# ls -R /sys/sysfs_demo//sys/sysfs_demo/:node_one      node_two      sysfs_demo_2/sys/sysfs_demo/sysfs_demo_2:node_four   node_three

  1 #define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__  2   3 #include <linux/init.h>  4 #include <linux/module.h>  5 #include <linux/kobject.h>  6 #include <linux/device.h>  7   8 static struct kobject *k_obj = NULL;  9 static struct kobject *k_obj_2 = NULL; 10  11 static char node_one_buf[20] = {0}; 12  13 static ssize_t sysfs_demo_show_node_one(struct kobject *kobj, struct kobj_attribute *attr, char * buf) 14 { 15     pr_info("enter, node: %s\n", attr->attr.name); 16     return sprintf(buf, "%s: %s\n", attr->attr.name, node_one_buf); 17 } 18  19 static ssize_t sysfs_demo_store_node_one(struct kobject *kobj, struct kobj_attribute *attr, const char * buf, size_t n) 20 { 21     pr_info("enter, node: %s\n", attr->attr.name); 22  23     sprintf(node_one_buf, "%s", buf); 24  25     return n; 26 } 27  28 static struct kobj_attribute node_one_attribute = 29     __ATTR(node_one, S_IWUSR|S_IRUGO, sysfs_demo_show_node_one, sysfs_demo_store_node_one); 30  31 static ssize_t sysfs_demo_show_node_two(struct kobject *kobj, struct kobj_attribute *attr, char * buf) 32 { 33  34     return sprintf(buf, "%s\n", attr->attr.name); 35 } 36  37 static struct kobj_attribute node_two_attribute = 38     __ATTR(node_two, S_IWUSR|S_IRUGO, sysfs_demo_show_node_two, NULL); 39  40 static struct attribute *sysfs_demo_attributes[] = { 41     &node_one_attribute.attr, 42     &node_two_attribute.attr, 43     NULL 44 }; 45  46 static const struct attribute_group sysfs_demo_attr_group = { 47     .attrs = sysfs_demo_attributes, 48 }; 49  50 static char node_three_buf[20] = {0}; 51  52 static ssize_t sysfs_demo_show_node_three(struct kobject *kobj, struct kobj_attribute *attr, char * buf) 53 { 54     pr_info("enter, node: %s\n", attr->attr.name); 55     return sprintf(buf, "%s: %s\n", attr->attr.name, node_three_buf); 56 } 57  58 static ssize_t sysfs_demo_store_node_three(struct kobject *kobj, struct kobj_attribute *attr, const char * buf, size_t n) 59 { 60     pr_info("enter, node: %s\n", attr->attr.name); 61  62     sprintf(node_three_buf, "%s", buf); 63  64     return n; 65 } 66  67 static struct kobj_attribute node_three_attribute = 68     __ATTR(node_three, S_IWUSR|S_IRUGO, sysfs_demo_show_node_three, sysfs_demo_store_node_three); 69  70 static ssize_t sysfs_demo_show_node_four(struct kobject *kobj, struct kobj_attribute *attr, char * buf) 71 { 72  73     return sprintf(buf, "%s\n", attr->attr.name); 74 } 75  76 static struct kobj_attribute node_four_attribute = 77     __ATTR(node_four, S_IWUSR|S_IRUGO, sysfs_demo_show_node_four, NULL); 78  79 static struct attribute *sysfs_demo2_attributes[] = { 80     &node_three_attribute.attr, 81     &node_four_attribute.attr, 82     NULL 83 }; 84  85 static const struct attribute_group sysfs_demo2_attr_group = { 86     .attrs = sysfs_demo2_attributes, 87 }; 88  89 static int __init sysfs_demo_init(void) 90 { 91     if ((k_obj = kobject_create_and_add("sysfs_demo", NULL)) == NULL ) { 92         pr_err("sysfs_demo sys node create error \n"); 93         goto out; 94     } 95  96     if(sysfs_create_group(k_obj, &sysfs_demo_attr_group) ) { 97         pr_err("sysfs_create_group failed\n"); 98         goto out2; 99     }100 101     if ((k_obj_2 = kobject_create_and_add("sysfs_demo_2", k_obj)) == NULL ) {102         pr_err("hwinfo sys node create error \n");103         goto out3;104     }105 106     if(sysfs_create_group(k_obj_2, &sysfs_demo2_attr_group) ) {107         pr_err("sysfs_create_group failed\n");108         goto out4;109     }110 111     pr_info("enter.\n");112     return 0;113 out4:114     kobject_put(k_obj_2);115 out3:116     sysfs_remove_group(k_obj, &sysfs_demo_attr_group);117 out2:118     kobject_put(k_obj);119 out:120     return -1;121 }122 module_init(sysfs_demo_init);123 124 static void __exit sysfs_demo_exit(void)125 {126     pr_info("enter.\n");127 128     if (k_obj) {129         sysfs_remove_group(k_obj, &sysfs_demo_attr_group);130         if (k_obj_2) {131             sysfs_remove_group(k_obj_2, &sysfs_demo2_attr_group);132             kobject_put(k_obj_2);133         }134         kobject_put(k_obj);135     }136 137 }138 module_exit(sysfs_demo_exit);139 140 MODULE_LICENSE("GPL");