kobject.h

Go to the documentation of this file.

// SPDX-License-Identifier: GPL-2.0
/*
 * kobject.h - generic kernel object infrastructure.
 *
 * Copyright (c) 2002-2003 Patrick Mochel
 * Copyright (c) 2002-2003 Open Source Development Labs
 * Copyright (c) 2006-2008 Greg Kroah-Hartman <greg@kroah.com>
 * Copyright (c) 2006-2008 Novell Inc.
 *
 * Please read Documentation/core-api/kobject.rst before using the kobject
 * interface, ESPECIALLY the parts about reference counts and object
 * destructors.
 */
 
#ifndef _KOBJECT_H_
#define _KOBJECT_H_
 
#include <linux/types.h>
#include <linux/list.h>
#include <linux/sysfs.h>
#include <linux/compiler.h>
#include <linux/container_of.h>
#include <linux/spinlock.h>
#include <linux/kref.h>
#include <linux/kobject_ns.h>
#include <linux/wait.h>
#include <linux/atomic.h>
#include <linux/workqueue.h>
#include <linux/uidgid.h>
 
#define UEVENT_HELPER_PATH_LEN      256
#define UEVENT_NUM_ENVP         64  /* number of env pointers */
#define UEVENT_BUFFER_SIZE      2048    /* buffer for the variables */
 
#ifdef CONFIG_UEVENT_HELPER
/* path to the userspace helper executed on an event */
extern char uevent_helper[];
#endif
 
/* counter to tag the uevent, read only except for the kobject core */
extern atomic64_t uevent_seqnum;
 
/*
 * The actions here must match the index to the string array
 * in lib/kobject_uevent.c
 *
 * Do not add new actions here without checking with the driver-core
 * maintainers. Action strings are not meant to express subsystem
 * or device specific properties. In most cases you want to send a
 * kobject_uevent_env(kobj, KOBJ_CHANGE, env) with additional event
 * specific variables added to the event environment.
 */
enum kobject_action {
    KOBJ_ADD,
    KOBJ_REMOVE,
    KOBJ_CHANGE,
    KOBJ_MOVE,
    KOBJ_ONLINE,
    KOBJ_OFFLINE,
    KOBJ_BIND,
    KOBJ_UNBIND,
};
 
struct kobject {
    const char      *name;
    struct list_head    entry;
    struct kobject      *parent;
    struct kset     *kset;
    const struct kobj_type  *ktype;
    struct kernfs_node  *sd; /* sysfs directory entry */
    struct kref     kref;
 
    unsigned int state_initialized:1;
    unsigned int state_in_sysfs:1;
    unsigned int state_add_uevent_sent:1;
    unsigned int state_remove_uevent_sent:1;
    unsigned int uevent_suppress:1;
 
#ifdef CONFIG_DEBUG_KOBJECT_RELEASE
    struct delayed_work release;
#endif
};
 
__printf(2, 3) int kobject_set_name(struct kobject *kobj, const char *name, ...);
__printf(2, 0) int kobject_set_name_vargs(struct kobject *kobj, const char *fmt, va_list vargs);
 
#define kobject_name(kobj) (((const struct kobject *)(const void *)(kobj))->name)
 
void kobject_init(struct kobject *kobj, const struct kobj_type *ktype);
__printf(3, 4) __must_check int kobject_add(struct kobject *kobj,
                        struct kobject *parent,
                        const char *fmt, ...);
__printf(4, 5) __must_check int kobject_init_and_add(struct kobject *kobj,
                             const struct kobj_type *ktype,
                             struct kobject *parent,
                             const char *fmt, ...);
 
void kobject_del(struct kobject *kobj);
 
struct kobject * __must_check kobject_create_and_add(const char *name, struct kobject *parent);
 
int __must_check kobject_rename(struct kobject *, const char *new_name);
int __must_check kobject_move(struct kobject *, struct kobject *);
 
struct kobject *kobject_get(struct kobject *kobj);
struct kobject * __must_check kobject_get_unless_zero(struct kobject *kobj);
void kobject_put(struct kobject *kobj);
 
const struct ns_common *kobject_namespace(const struct kobject *kobj);
void kobject_get_ownership(const struct kobject *kobj, kuid_t *uid, kgid_t *gid);
char *kobject_get_path(const void *kobj, gfp_t flag);
 
struct kobj_type {
    void (*release)(struct kobject *kobj);
    const struct sysfs_ops *sysfs_ops;
    const struct attribute_group **default_groups;
    const struct kobj_ns_type_operations *(*child_ns_type)(const struct kobject *kobj);
    const struct ns_common *(*namespace)(const struct kobject *kobj);
    void (*get_ownership)(const struct kobject *kobj, kuid_t *uid, kgid_t *gid);
};
 
struct kobj_uevent_env {
    char *argv[3];
    char *envp[UEVENT_NUM_ENVP];
    int envp_idx;
    char buf[UEVENT_BUFFER_SIZE];
    int buflen;
};
 
struct kset_uevent_ops {
    int (* const filter)(const struct kobject *kobj);
    const char *(* const name)(const struct kobject *kobj);
    int (* const uevent)(const struct kobject *kobj, struct kobj_uevent_env *env);
};
 
struct kobj_attribute {
    struct attribute attr;
    ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr,
            char *buf);
    ssize_t (*store)(struct kobject *kobj, struct kobj_attribute *attr,
             const char *buf, size_t count);
};
 
extern const struct sysfs_ops kobj_sysfs_ops;
 
struct sock;
 
struct kset {
    struct list_head list;
    spinlock_t list_lock;
    struct kobject kobj;
    const struct kset_uevent_ops *uevent_ops;
} __randomize_layout;
 
void kset_init(struct kset *kset);
int __must_check kset_register(struct kset *kset);
void kset_unregister(struct kset *kset);
struct kset * __must_check kset_create_and_add(const char *name, const struct kset_uevent_ops *u,
                           struct kobject *parent_kobj);
 
static inline struct kset *to_kset(struct kobject *kobj)
{
    return kobj ? container_of(kobj, struct kset, kobj) : NULL;
}
 
static inline struct kset *kset_get(struct kset *k)
{
    return k ? to_kset(kobject_get(&k->kobj)) : NULL;
}
 
static inline void kset_put(struct kset *k)
{
    kobject_put(&k->kobj);
}
 
static inline const struct kobj_type *get_ktype(const struct kobject *kobj)
{
    return kobj->ktype;
}
 
struct kobject *kset_find_obj(struct kset *, const char *);
 
/* The global /sys/kernel/ kobject for people to chain off of */
extern struct kobject *kernel_kobj;
/* The global /sys/kernel/mm/ kobject for people to chain off of */
extern struct kobject *mm_kobj;
/* The global /sys/hypervisor/ kobject for people to chain off of */
extern struct kobject *hypervisor_kobj;
/* The global /sys/power/ kobject for people to chain off of */
extern struct kobject *power_kobj;
/* The global /sys/firmware/ kobject for people to chain off of */
extern struct kobject *firmware_kobj;
 
/*
 * kobject_uevent() -- a macro, deliberately.
 *
 * mainline has a function here, and DCL's DCL/linux_cdev_shim.c:151 still
 * defines one (the no-op body a udev notification would need). It cannot stay
 * a *declaration*, because virtio_console.c:1654 calls it as
 *
 *     kobject_uevent(&port->dev->kobj, KOBJ_CHANGE);
 *
 * and `port->dev->kobj` is a member that does not exist: <linux/fs.h>'s
 * struct device -- the one file this tree must not edit -- carries `kobj_name`
 * at offset 0 (the slot mainline's kobj.name occupies) and no `kobj`. A macro
 * whose parameters never appear in its replacement list never parses them, so
 * the whole invocation is replaced before the parser sees `->kobj`. Same
 * idiom as spin_lock(l) in <linux/spinlock.h>:36.
 *
 * The two definitions have to agree about not existing: this replaces the
 * declaration rather than being added beside it, because a declaration that
 * survives would still type-check `&port->dev->kobj` in any translation unit
 * that happened to include this header before <linux/sysfs.h>. And the
 * behaviour is unchanged -- the shim's body is empty. DCL has no udev, so the
 * event had nowhere to go either way.
 *
 * kobject_uevent_env() joined it when drm_drv.c:599
 *
 *     return kobject_uevent_env(&dev->primary->kdev->kobj, KOBJ_CHANGE, envp);
 *
 * became the first caller: same absent member, and this one uses the
 * return value, so the macro answers (0) -- "event delivered", the answer
 * that keeps drm_dev_wedged_event() on its success path.
 */
#define kobject_uevent(kobj, action)  ((void)0)
#define kobject_uevent_env(kobj, action, envp)  (0)
int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count);
 
__printf(2, 3)
int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...);
 
#endif /* _KOBJECT_H_ */