include/linux/kobject.h

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * kobject.h - generic kernel object infrastructure.
   4  *
   5  * Copyright (c) 2002-2003 Patrick Mochel
   6  * Copyright (c) 2002-2003 Open Source Development Labs
   7  * Copyright (c) 2006-2008 Greg Kroah-Hartman <greg@kroah.com>
   8  * Copyright (c) 2006-2008 Novell Inc.
   9  *
  10  * Please read Documentation/kobject.txt before using the kobject
  11  * interface, ESPECIALLY the parts about reference counts and object
  12  * destructors.
  13  */
  14
  15 #ifndef _KOBJECT_H_
  16 #define _KOBJECT_H_
  17
  18 #include <linux/types.h>
  19 #include <linux/list.h>
  20 #include <linux/sysfs.h>
  21 #include <linux/compiler.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/kref.h>
  24 #include <linux/kobject_ns.h>
  25 #include <linux/kernel.h>
  26 #include <linux/wait.h>
  27 #include <linux/atomic.h>
  28 #include <linux/workqueue.h>
  29 #include <linux/uidgid.h>
  30
  31 #define UEVENT_HELPER_PATH_LEN          256
  32 #define UEVENT_NUM_ENVP                 32      /* number of env pointers */
  33 #define UEVENT_BUFFER_SIZE              2048    /* buffer for the variables */
  34
  35 #ifdef CONFIG_UEVENT_HELPER
  36 /* path to the userspace helper executed on an event */
  37 extern char uevent_helper[];
  38 #endif
  39
  40 /* counter to tag the uevent, read only except for the kobject core */
  41 extern u64 uevent_seqnum;
  42
  43 /*
  44  * The actions here must match the index to the string array
  45  * in lib/kobject_uevent.c
  46  *
  47  * Do not add new actions here without checking with the driver-core
  48  * maintainers. Action strings are not meant to express subsystem
  49  * or device specific properties. In most cases you want to send a
  50  * kobject_uevent_env(kobj, KOBJ_CHANGE, env) with additional event
  51  * specific variables added to the event environment.
  52  */
  53 enum kobject_action {
  54         KOBJ_ADD,
  55         KOBJ_REMOVE,
  56         KOBJ_CHANGE,
  57         KOBJ_MOVE,
  58         KOBJ_ONLINE,
  59         KOBJ_OFFLINE,
  60         KOBJ_BIND,
  61         KOBJ_UNBIND,
  62         KOBJ_MAX
  63 };
  64
  65 struct kobject {
  66         const char              *name;
  67         struct list_head        entry;
  68         struct kobject          *parent;
  69         struct kset             *kset;
  70         struct kobj_type        *ktype;
  71         struct kernfs_node      *sd; /* sysfs directory entry */
  72         struct kref             kref;
  73 #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
  74         struct delayed_work     release;
  75 #endif
  76         unsigned int state_initialized:1;
  77         unsigned int state_in_sysfs:1;
  78         unsigned int state_add_uevent_sent:1;
  79         unsigned int state_remove_uevent_sent:1;
  80         unsigned int uevent_suppress:1;
  81 };
  82
  83 extern __printf(2, 3)
  84 int kobject_set_name(struct kobject *kobj, const char *name, ...);
  85 extern __printf(2, 0)
  86 int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
  87                            va_list vargs);
  88
  89 static inline const char *kobject_name(const struct kobject *kobj)
  90 {
  91         return kobj->name;
  92 }
  93
  94 extern void kobject_init(struct kobject *kobj, struct kobj_type *ktype);
  95 extern __printf(3, 4) __must_check
  96 int kobject_add(struct kobject *kobj, struct kobject *parent,
  97                 const char *fmt, ...);
  98 extern __printf(4, 5) __must_check
  99 int kobject_init_and_add(struct kobject *kobj,
 100                          struct kobj_type *ktype, struct kobject *parent,
 101                          const char *fmt, ...);
 102
 103 extern void kobject_del(struct kobject *kobj);
 104
 105 extern struct kobject * __must_check kobject_create(void);
 106 extern struct kobject * __must_check kobject_create_and_add(const char *name,
 107                                                 struct kobject *parent);
 108
 109 extern int __must_check kobject_rename(struct kobject *, const char *new_name);
 110 extern int __must_check kobject_move(struct kobject *, struct kobject *);
 111
 112 extern struct kobject *kobject_get(struct kobject *kobj);
 113 extern struct kobject * __must_check kobject_get_unless_zero(
 114                                                 struct kobject *kobj);
 115 extern void kobject_put(struct kobject *kobj);
 116
 117 extern const void *kobject_namespace(struct kobject *kobj);
 118 extern void kobject_get_ownership(struct kobject *kobj,
 119                                   kuid_t *uid, kgid_t *gid);
 120 extern char *kobject_get_path(struct kobject *kobj, gfp_t flag);
 121
 122 /**
 123  * kobject_has_children - Returns whether a kobject has children.
 124  * @kobj: the object to test
 125  *
 126  * This will return whether a kobject has other kobjects as children.
 127  *
 128  * It does NOT account for the presence of attribute files, only sub
 129  * directories. It also assumes there is no concurrent addition or
 130  * removal of such children, and thus relies on external locking.
 131  */
 132 static inline bool kobject_has_children(struct kobject *kobj)
 133 {
 134         WARN_ON_ONCE(kref_read(&kobj->kref) == 0);
 135
 136         return kobj->sd && kobj->sd->dir.subdirs;
 137 }
 138
 139 struct kobj_type {
 140         void (*release)(struct kobject *kobj);
 141         const struct sysfs_ops *sysfs_ops;
 142         struct attribute **default_attrs;
 143         const struct kobj_ns_type_operations *(*child_ns_type)(struct kobject *kobj);
 144         const void *(*namespace)(struct kobject *kobj);
 145         void (*get_ownership)(struct kobject *kobj, kuid_t *uid, kgid_t *gid);
 146 };
 147
 148 struct kobj_uevent_env {
 149         char *argv[3];
 150         char *envp[UEVENT_NUM_ENVP];
 151         int envp_idx;
 152         char buf[UEVENT_BUFFER_SIZE];
 153         int buflen;
 154 };
 155
 156 struct kset_uevent_ops {
 157         int (* const filter)(struct kset *kset, struct kobject *kobj);
 158         const char *(* const name)(struct kset *kset, struct kobject *kobj);
 159         int (* const uevent)(struct kset *kset, struct kobject *kobj,
 160                       struct kobj_uevent_env *env);
 161 };
 162
 163 struct kobj_attribute {
 164         struct attribute attr;
 165         ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr,
 166                         char *buf);
 167         ssize_t (*store)(struct kobject *kobj, struct kobj_attribute *attr,
 168                          const char *buf, size_t count);
 169 };
 170
 171 extern const struct sysfs_ops kobj_sysfs_ops;
 172
 173 struct sock;
 174
 175 /**
 176  * struct kset - a set of kobjects of a specific type, belonging to a specific subsystem.
 177  *
 178  * A kset defines a group of kobjects.  They can be individually
 179  * different "types" but overall these kobjects all want to be grouped
 180  * together and operated on in the same manner.  ksets are used to
 181  * define the attribute callbacks and other common events that happen to
 182  * a kobject.
 183  *
 184  * @list: the list of all kobjects for this kset
 185  * @list_lock: a lock for iterating over the kobjects
 186  * @kobj: the embedded kobject for this kset (recursion, isn't it fun...)
 187  * @uevent_ops: the set of uevent operations for this kset.  These are
 188  * called whenever a kobject has something happen to it so that the kset
 189  * can add new environment variables, or filter out the uevents if so
 190  * desired.
 191  */
 192 struct kset {
 193         struct list_head list;
 194         spinlock_t list_lock;
 195         struct kobject kobj;
 196         const struct kset_uevent_ops *uevent_ops;
 197 } __randomize_layout;
 198
 199 extern void kset_init(struct kset *kset);
 200 extern int __must_check kset_register(struct kset *kset);
 201 extern void kset_unregister(struct kset *kset);
 202 extern struct kset * __must_check kset_create_and_add(const char *name,
 203                                                 const struct kset_uevent_ops *u,
 204                                                 struct kobject *parent_kobj);
 205
 206 static inline struct kset *to_kset(struct kobject *kobj)
 207 {
 208         return kobj ? container_of(kobj, struct kset, kobj) : NULL;
 209 }
 210
 211 static inline struct kset *kset_get(struct kset *k)
 212 {
 213         return k ? to_kset(kobject_get(&k->kobj)) : NULL;
 214 }
 215
 216 static inline void kset_put(struct kset *k)
 217 {
 218         kobject_put(&k->kobj);
 219 }
 220
 221 static inline struct kobj_type *get_ktype(struct kobject *kobj)
 222 {
 223         return kobj->ktype;
 224 }
 225
 226 extern struct kobject *kset_find_obj(struct kset *, const char *);
 227
 228 /* The global /sys/kernel/ kobject for people to chain off of */
 229 extern struct kobject *kernel_kobj;
 230 /* The global /sys/kernel/mm/ kobject for people to chain off of */
 231 extern struct kobject *mm_kobj;
 232 /* The global /sys/hypervisor/ kobject for people to chain off of */
 233 extern struct kobject *hypervisor_kobj;
 234 /* The global /sys/power/ kobject for people to chain off of */
 235 extern struct kobject *power_kobj;
 236 /* The global /sys/firmware/ kobject for people to chain off of */
 237 extern struct kobject *firmware_kobj;
 238
 239 int kobject_uevent(struct kobject *kobj, enum kobject_action action);
 240 int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
 241                         char *envp[]);
 242 int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count);
 243
 244 __printf(2, 3)
 245 int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...);
 246
 247 #endif /* _KOBJECT_H_ */