diff options
Diffstat (limited to 'Documentation/kobject.txt')
| -rw-r--r-- | Documentation/kobject.txt | 178 |
1 files changed, 59 insertions, 119 deletions
diff --git a/Documentation/kobject.txt b/Documentation/kobject.txt index e44855513b3..8ee49ee7c96 100644 --- a/Documentation/kobject.txt +++ b/Documentation/kobject.txt @@ -27,7 +27,6 @@ in detail, and briefly here: - kobjects a simple object. - kset a set of objects of a certain type. - ktype a set of helpers for objects of a common type. -- subsystem a controlling object for a number of ksets. The kobject infrastructure maintains a close relationship with the @@ -54,13 +53,15 @@ embedded in larger data structures and replace fields they duplicate. 1.2 Definition struct kobject { + const char * k_name; char name[KOBJ_NAME_LEN]; - atomic_t refcount; + struct kref kref; struct list_head entry; struct kobject * parent; struct kset * kset; struct kobj_type * ktype; - struct dentry * dentry; + struct sysfs_dirent * sd; + wait_queue_head_t poll; }; void kobject_init(struct kobject *); @@ -137,8 +138,7 @@ If a kobject does not have a parent when it is registered, its parent becomes its dominant kset. If a kobject does not have a parent nor a dominant kset, its directory -is created at the top-level of the sysfs partition. This should only -happen for kobjects that are embedded in a struct subsystem. +is created at the top-level of the sysfs partition. @@ -150,10 +150,10 @@ A kset is a set of kobjects that are embedded in the same type. struct kset { - struct subsystem * subsys; struct kobj_type * ktype; struct list_head list; struct kobject kobj; + struct kset_uevent_ops * uevent_ops; }; @@ -169,8 +169,7 @@ struct kobject * kset_find_obj(struct kset *, char *); The type that the kobjects are embedded in is described by the ktype -pointer. The subsystem that the kobject belongs to is pointed to by the -subsys pointer. +pointer. A kset contains a kobject itself, meaning that it may be registered in the kobject hierarchy and exported via sysfs. More importantly, the @@ -209,6 +208,58 @@ the hierarchy. kset_find_obj() may be used to locate a kobject with a particular name. The kobject, if found, is returned. +There are also some helper functions which names point to the formerly +existing "struct subsystem", whose functions have been taken over by +ksets. + + +decl_subsys(name,type,uevent_ops) + +Declares a kset named '<name>_subsys' of type <type> with +uevent_ops <uevent_ops>. For example, + +decl_subsys(devices, &ktype_device, &device_uevent_ops); + +is equivalent to doing: + +struct kset devices_subsys = { + .kobj = { + .name = "devices", + }, + .ktype = &ktype_devices, + .uevent_ops = &device_uevent_ops, +}; + + +The objects that are registered with a subsystem that use the +subsystem's default list must have their kset ptr set properly. These +objects may have embedded kobjects or ksets. The +following helpers make setting the kset easier: + + +kobj_set_kset_s(obj,subsys) + +- Assumes that obj->kobj exists, and is a struct kobject. +- Sets the kset of that kobject to the kset <subsys>. + + +kset_set_kset_s(obj,subsys) + +- Assumes that obj->kset exists, and is a struct kset. +- Sets the kset of the embedded kobject to the kset <subsys>. + +subsys_set_kset(obj,subsys) + +- Assumes obj->subsys exists, and is a struct subsystem. +- Sets obj->subsys.kset.kobj.kset to the subsystem's embedded kset. + +void subsystem_init(struct kset *s); +int subsystem_register(struct kset *s); +void subsystem_unregister(struct kset *s); +struct kset *subsys_get(struct kset *s); +void kset_put(struct kset *s); + +These are just wrappers around the respective kset_* functions. 2.3 sysfs @@ -254,114 +305,3 @@ Instances of struct kobj_type are not registered; only referenced by the kset. A kobj_type may be referenced by an arbitrary number of ksets, as there may be disparate sets of identical objects. - - -4. subsystems - -4.1 Description - -A subsystem represents a significant entity of code that maintains an -arbitrary number of sets of objects of various types. Since the number -of ksets and the type of objects they contain are variable, a -generic representation of a subsystem is minimal. - - -struct subsystem { - struct kset kset; - struct rw_semaphore rwsem; -}; - -int subsystem_register(struct subsystem *); -void subsystem_unregister(struct subsystem *); - -struct subsystem * subsys_get(struct subsystem * s); -void subsys_put(struct subsystem * s); - - -A subsystem contains an embedded kset so: - -- It can be represented in the object hierarchy via the kset's - embedded kobject. - -- It can maintain a default list of objects of one type. - -Additional ksets may attach to the subsystem simply by referencing the -subsystem before they are registered. (This one-way reference means -that there is no way to determine the ksets that are attached to the -subsystem.) - -All ksets that are attached to a subsystem share the subsystem's R/W -semaphore. - - -4.2 subsystem Programming Interface. - -The subsystem programming interface is simple and does not offer the -flexibility that the kset and kobject programming interfaces do. They -may be registered and unregistered, as well as reference counted. Each -call forwards the calls to their embedded ksets (which forward the -calls to their embedded kobjects). - - -4.3 Helpers - -A number of macros are available to make dealing with subsystems and -their embedded objects easier. - - -decl_subsys(name,type) - -Declares a subsystem named '<name>_subsys', with an embedded kset of -type <type>. For example, - -decl_subsys(devices,&ktype_devices); - -is equivalent to doing: - -struct subsystem device_subsys = { - .kset = { - .kobj = { - .name = "devices", - }, - .ktype = &ktype_devices, - } -}; - - -The objects that are registered with a subsystem that use the -subsystem's default list must have their kset ptr set properly. These -objects may have embedded kobjects, ksets, or other subsystems. The -following helpers make setting the kset easier: - - -kobj_set_kset_s(obj,subsys) - -- Assumes that obj->kobj exists, and is a struct kobject. -- Sets the kset of that kobject to the subsystem's embedded kset. - - -kset_set_kset_s(obj,subsys) - -- Assumes that obj->kset exists, and is a struct kset. -- Sets the kset of the embedded kobject to the subsystem's - embedded kset. - -subsys_set_kset(obj,subsys) - -- Assumes obj->subsys exists, and is a struct subsystem. -- Sets obj->subsys.kset.kobj.kset to the subsystem's embedded kset. - - -4.4 sysfs - -subsystems are represented in sysfs via their embedded kobjects. They -follow the same rules as previously mentioned with no exceptions. They -typically receive a top-level directory in sysfs, except when their -embedded kobject is part of another kset, or the parent of the -embedded kobject is explicitly set. - -Note that the subsystem's embedded kset must be 'attached' to the -subsystem itself in order to use its rwsem. This is done after -kset_add() has been called. (Not before, because kset_add() uses its -subsystem for a default parent if it doesn't already have one). - |