Linux kernel 之 kobject

总听有人说 Linux kernel 拥有一团无比巨大看似杂乱无章其实有迹可循的链表，今天参考一下其他大牛的相关资料记录一下。

kset 结构体

    151 /**

    152  * struct kset - a set of kobjects of a specific type, belonging to a specific subsystem.

    153  *

    154  * A kset defines a group of kobjects.  They can be individually

    155  * different "types" but overall these kobjects all want to be grouped

    156  * together and operated on in the same manner.  ksets are used to

    157  * define the attribute callbacks and other common events that happen to

    158  * a kobject.

    159  *

    160  * @list: the list of all kobjects for this kset

    161  * @list_lock: a lock for iterating over the kobjects

    162  * @kobj: the embedded kobject for this kset (recursion, isn't it fun...)

    163  * @uevent_ops: the set of uevent operations for this kset.  These are

    164  * called whenever a kobject has something happen to it so that the kset

    165  * can add new environment variables, or filter out the uevents if so

    166  * desired.

    167  */

    168 struct kset {

    169     struct list_head list;       // 这里边包含了这个 kset 所有的 kobject

    170     spinlock_t list_lock;

    171     struct kobject kobj;         // 一个嵌入在里面的kobject

    172     const struct kset_uevent_ops *uevent_ops;     // 里面包含热拔插事件发生时的响应操作

    173 };

* #### kobject 结构体

    //  include/linux/kobject.h

     63 struct kobject {

     64     const char      *name;       // 名字

     65     struct list_head    entry;   // 连接到 kset 建立层次结构

     66     struct kobject      *parent;  // 上一个节点

     67     struct kset     *kset;        // 指向所属的 kset

     68     struct kobj_type    *ktype;   // 指向所属的 ktype

     69     struct kernfs_node  *sd; /* sysfs directory entry */     //  文件系统内的sysfs 的node

     70     struct kref     kref;         // 引用计数

     71 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE

     72     struct delayed_work release;

     73 #endif

     74     unsigned int state_initialized:1;     //  初始化状态，只占 1 个位的空间，应用了位域

     75     unsigned int state_in_sysfs:1;

     76     unsigned int state_add_uevent_sent:1;

     77     unsigned int state_remove_uevent_sent:1;

     78     unsigned int uevent_suppress:1;

     79 };

* #### kobj_type 结构体

    116 struct kobj_type {

    117     void (*release)(struct kobject *kobj);

    118     const struct sysfs_ops *sysfs_ops;

    119     struct attribute **default_attrs;

    120     const struct kobj_ns_type_operations *(*child_ns_type)(struct kobject *kobj);

    121     const void *(*namespace)(struct kobject *kobj);

    122 };

* #### kobject_init - initialize a kobject structure ：初始化

    // lib/kobject.c

    // 318  * This function will properly initialize a kobject such that it can then

    // 319  * be passed to the kobject_add() call.   等下还有kobject_add()

    // 321  * After this function is called, the kobject MUST be cleaned up by a call

    // 322  * to kobject_put(), not by a call to kfree directly to ensure that all of

    // 323  * the memory is cleaned up properly.      必须用 kobject_put 去释放，而不是 kfree

     325 void kobject_init(struct kobject *kobj, struct kobj_type *ktype)

     326 {

     327     char *err_str;

     328

     329     if (!kobj) {

     330         err_str = "invalid kobject pointer!";

     331         goto error;

     332     }

     333     if (!ktype) {

     334         err_str = "must have a ktype to be initialized properly!\n";

     335         goto error;

     336     }

     337     if (kobj->state_initialized) {

     338         /* do not error out as sometimes we can recover */

     339         printk(KERN_ERR "kobject (%p): tried to init an initialized "

     340                "object, something is seriously wrong.\n", kobj);

     341         dump_stack();

     342     }

     343

     344     kobject_init_internal(kobj);       // 初始化有关的成员

     345     kobj->ktype = ktype;

     346     return;

     347

     348 error:

     349     printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);

     350     dump_stack();

     351 }

     352 EXPORT_SYMBOL(kobject_init);

    // kobject_init_internal 一些属性的初始化

     187 static void kobject_init_internal(struct kobject *kobj)

     188 {

     189     if (!kobj)

     190         return;

     191     kref_init(&kobj->kref);     // 设置计数为1

     192     INIT_LIST_HEAD(&kobj->entry);

     193     kobj->state_in_sysfs = 0;

     194     kobj->state_add_uevent_sent = 0;

     195     kobj->state_remove_uevent_sent = 0;

     196     kobj->state_initialized = 1;        // 设置初始化状态

* #### 通过总线注册函数解析 kset , kobjectd , ktype 这些结构体的关系。

    // drivers/base/bus.c

    // 这里先将 两个变量作为全局变量

      25 /* /sys/devices/system */

      26 static struct kset *system_kset;

     178 static struct kset *bus_kset;

    // 入口函数

    1278 int __init buses_init(void)

    1279 {            // kset 创建和添加  , 名字为"bus"  "bus事件操作" “父project 为空”

    1280     bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);

    1281     if (!bus_kset)

    1282         return -ENOMEM;

    1283

    1284     system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);

    1285     if (!system_kset)

    1286         return -ENOMEM;

    1287

    1288     return 0;

    1289 }

    // kset_create_and_add

    // 头文件 include/linux/kobject.h

    178 extern struct kset * __must_check kset_create_and_add(const char *name,

    179                         const struct kset_uevent_ops *u,

    180                         struct kobject *parent_kobj);   

    // 源代码  lib/kobject.c

     936 struct kset *kset_create_and_add(const char *name,

     937                  const struct kset_uevent_ops *uevent_ops,

     938                  struct kobject *parent_kobj)

     939 {

     940     struct kset *kset;

     941     int error;

     942                   // 名字为"bus" ，申请一段空间并初始化相关kset 属性

     943     kset = kset_create(name, uevent_ops, parent_kobj);

     944     if (!kset)

     945         return NULL;

     946     error = kset_register(kset);  // 注册

     947     if (error) {

     948         kfree(kset);

     949         return NULL;

     950     }

     951     return kset;

     952 }

    //  lib/kobject.c

    //  kset_register

     809 int kset_register(struct kset *k)

     810 {

     811     int err;

     812

     813     if (!k)

     814         return -EINVAL;

     815     // 初始化

     816     kset_init(k);

     817     err = kobject_add_internal(&k->kobj);   // 接下

     818     if (err)

     819         return err;

     820     kobject_uevent(&k->kobj, KOBJ_ADD);

     821     return 0;

     822 }

     823 EXPORT_SYMBOL(kset_register);

    // kset 初始化

     767 void kset_init(struct kset *k)

     768 {   // 这个在上面已经跟过了

      // 最主要是初始化了 state_initialized = 1

     769     kobject_init_internal(&k->kobj);

     770     INIT_LIST_HEAD(&k->list); // 设置为链表头

     771     spin_lock_init(&k->list_lock);

     772 }

    // kobject_add_internal

     200 static int kobject_add_internal(struct kobject *kobj)

     201 {

     202     int error = 0;

     203     struct kobject *parent;

     204

     205     if (!kobj)

     206         return -ENOENT;

     207

     208     if (!kobj->name || !kobj->name[0]) {

     209         WARN(1, "kobject: (%p): attempted to be registered with empty "

     210              "name!\n", kobj);

     211         return -EINVAL;

     212     }

     213

     214     parent = kobject_get(kobj->parent);

     215

     216     /* join kset if set, use it as parent if we do not already have one */

     217     if (kobj->kset) {

     218         if (!parent)

     219             parent = kobject_get(&kobj->kset->kobj);

     220         kobj_kset_join(kobj);

     221         kobj->parent = parent;

     222     }

巴特西

Linux kernel 之 kobject

总听有人说 Linux kernel 拥有一团无比巨大看似杂乱无章其实有迹可循的链表，今天参考一下其他大牛的相关资料记录一下。

kset 结构体

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