/* * kobject.c - library routines for handling generic kernel objects * * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org> * * This file is released under the GPLv2. * * * Please see the file Documentation/kobject.txt for critical information * about using the kobject interface. */ #include <linux/kobject.h> #include <linux/string.h> #include <linux/module.h> #include <linux/stat.h> #include <linux/slab.h> /** * populate_dir - populate directory with attributes. * @kobj: object we're working on. * * Most subsystems have a set of default attributes that * are associated with an object that registers with them. * This is a helper called during object registration that * loops through the default attributes of the subsystem * and creates attributes files for them in sysfs. * */ static int populate_dir(struct kobject * kobj) { struct kobj_type * t = get_ktype(kobj); struct attribute * attr; int error = 0; int i; if (t && t->default_attrs) { for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) { if ((error = sysfs_create_file(kobj,attr))) break; } } return error; } static int create_dir(struct kobject * kobj) { int error = 0; if (kobject_name(kobj)) { error = sysfs_create_dir(kobj); if (!error) { if ((error = populate_dir(kobj))) sysfs_remove_dir(kobj); } } return error; } static inline struct kobject * to_kobj(struct list_head * entry) { return container_of(entry,struct kobject,entry); } static int get_kobj_path_length(struct kobject *kobj) { int length = 1; struct kobject * parent = kobj; /* walk up the ancestors until we hit the one pointing to the * root. * Add 1 to strlen for leading '/' of each level. */ do { length += strlen(kobject_name(parent)) + 1; parent = parent->parent; } while (parent); return length; } static void fill_kobj_path(struct kobject *kobj, char *path, int length) { struct kobject * parent; --length; for (parent = kobj; parent; parent = parent->parent) { int cur = strlen(kobject_name(parent)); /* back up enough to print this name with '/' */ length -= cur; strncpy (path + length, kobject_name(parent), cur); *(path + --length) = '/'; } pr_debug("%s: path = '%s'\n",__FUNCTION__,path); } /** * kobject_get_path - generate and return the path associated with a given kobj * and kset pair. The result must be freed by the caller with kfree(). * * @kobj: kobject in question, with which to build the path * @gfp_mask: the allocation type used to allocate the path */ char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask) { char *path; int len; len = get_kobj_path_length(kobj); path = kmalloc(len, gfp_mask); if (!path) return NULL; memset(path, 0x00, len); fill_kobj_path(kobj, path, len); return path; } /** * kobject_init - initialize object. * @kobj: object in question. */ void kobject_init(struct kobject * kobj) { kref_init(&kobj->kref); INIT_LIST_HEAD(&kobj->entry); kobj->kset = kset_get(kobj->kset); } /** * unlink - remove kobject from kset list. * @kobj: kobject. * * Remove the kobject from the kset list and decrement * its parent's refcount. * This is separated out, so we can use it in both * kobject_del() and kobject_add() on error. */ static void unlink(struct kobject * kobj) { if (kobj->kset) { spin_lock(&kobj->kset->list_lock); list_del_init(&kobj->entry); spin_unlock(&kobj->kset->list_lock); } kobject_put(kobj); } /** * kobject_add - add an object to the hierarchy. * @kobj: object. */ int kobject_add(struct kobject * kobj) { int error = 0; struct kobject * parent; if (!(kobj = kobject_get(kobj))) return -ENOENT; if (!kobj->k_name) kobj->k_name = kobj->name; parent = kobject_get(kobj->parent); pr_debug("kobject %s: registering. parent: %s, set: %s\n", kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>", kobj->kset ? kobj->kset->kobj.name : "<NULL>" ); if (kobj->kset) { spin_lock(&kobj->kset->list_lock); if (!parent) parent = kobject_get(&kobj->kset->kobj); list_add_tail(&kobj->entry,&kobj->kset->list); spin_unlock(&kobj->kset->list_lock); } kobj->parent = parent; error = create_dir(kobj); if (error) { /* unlink does the kobject_put() for us */ unlink(kobj); if (parent) kobject_put(parent); } return error; } /** * kobject_register - initialize and add an object. * @kobj: object in question. */ int kobject_register(struct kobject * kobj) { int error = 0; if (kobj) { kobject_init(kobj); error = kobject_add(kobj); if (error) { printk("kobject_register failed for %s (%d)\n", kobject_name(kobj),error); dump_stack(); } else kobject_hotplug(kobj, KOBJ_ADD); } else error = -EINVAL; return error; } /** * kobject_set_name - Set the name of an object * @kobj: object. * @fmt: format string used to build the name * * If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated * string that @kobj->k_name points to. Otherwise, use the static * @kobj->name array. */ int kobject_set_name(struct kobject * kobj, const char * fmt, ...) { int error = 0; int limit = KOBJ_NAME_LEN; int need; va_list args; char * name; /* * First, try the static array */ va_start(args,fmt); need = vsnprintf(kobj->name,limit,fmt,args); va_end(args); if (need < limit) name = kobj->name; else { /* * Need more space? Allocate it and try again */ limit = need + 1; name = kmalloc(limit,GFP_KERNEL); if (!name) { error = -ENOMEM; goto Done; } va_start(args,fmt); need = vsnprintf(name,limit,fmt,args); va_end(args); /* Still? Give up. */ if (need >= limit) { kfree(name); error = -EFAULT; goto Done; } } /* Free the old name, if necessary. */ if (kobj->k_name && kobj->k_name != kobj->name) kfree(kobj->k_name); /* Now, set the new name */ kobj->k_name = name; Done: return error; } EXPORT_SYMBOL(kobject_set_name); /** * kobject_rename - change the name of an object * @kobj: object in question. * @new_name: object's new name */ int kobject_rename(struct kobject * kobj, const char *new_name) { int error = 0; kobj = kobject_get(kobj); if (!kobj) return -EINVAL; error = sysfs_rename_dir(kobj, new_name); kobject_put(kobj); return error; } /** * kobject_del - unlink kobject from hierarchy. * @kobj: object. */ void kobject_del(struct kobject * kobj) { sysfs_remove_dir(kobj); unlink(kobj); } /** * kobject_unregister - remove object from hierarchy and decrement refcount. * @kobj: object going away. */ void kobject_unregister(struct kobject * kobj) { pr_debug("kobject %s: unregistering\n",kobject_name(kobj)); kobject_hotplug(kobj, KOBJ_REMOVE); kobject_del(kobj); kobject_put(kobj); } /** * kobject_get - increment refcount for object. * @kobj: object. */ struct kobject * kobject_get(struct kobject * kobj) { if (kobj) kref_get(&kobj->kref); return kobj; } /** * kobject_cleanup - free kobject resources. * @kobj: object. */ void kobject_cleanup(struct kobject * kobj) { struct kobj_type * t = get_ktype(kobj); struct kset * s = kobj->kset; struct kobject * parent = kobj->parent; pr_debug("kobject %s: cleaning up\n",kobject_name(kobj)); if (kobj->k_name != kobj->name) kfree(kobj->k_name); kobj->k_name = NULL; if (t && t->release) t->release(kobj); if (s) kset_put(s); if (parent) kobject_put(parent); } static void kobject_release(struct kref *kref) { kobject_cleanup(container_of(kref, struct kobject, kref)); } /** * kobject_put - decrement refcount for object. * @kobj: object. * * Decrement the refcount, and if 0, call kobject_cleanup(). */ void kobject_put(struct kobject * kobj) { if (kobj) kref_put(&kobj->kref, kobject_release); } /** * kset_init - initialize a kset for use * @k: kset */ void kset_init(struct kset * k) { kobject_init(&k->kobj); INIT_LIST_HEAD(&k->list); spin_lock_init(&k->list_lock); } /** * kset_add - add a kset object to the hierarchy. * @k: kset. * * Simply, this adds the kset's embedded kobject to the * hierarchy. * We also try to make sure that the kset's embedded kobject * has a parent before it is added. We only care if the embedded * kobject is not part of a kset itself, since kobject_add() * assigns a parent in that case. * If that is the case, and the kset has a controlling subsystem, * then we set the kset's parent to be said subsystem. */ int kset_add(struct kset * k) { if (!k->kobj.parent && !k->kobj.kset && k->subsys) k->kobj.parent = &k->subsys->kset.kobj; return kobject_add(&k->kobj); } /** * kset_register - initialize and add a kset. * @k: kset. */ int kset_register(struct kset * k) { kset_init(k); return kset_add(k); } /** * kset_unregister - remove a kset. * @k: kset. */ void kset_unregister(struct kset * k) { kobject_unregister(&k->kobj); } /** * kset_find_obj - search for object in kset. * @kset: kset we're looking in. * @name: object's name. * * Lock kset via @kset->subsys, and iterate over @kset->list, * looking for a matching kobject. If matching object is found * take a reference and return the object. */ struct kobject * kset_find_obj(struct kset * kset, const char * name) { struct list_head * entry; struct kobject * ret = NULL; spin_lock(&kset->list_lock); list_for_each(entry,&kset->list) { struct kobject * k = to_kobj(entry); if (kobject_name(k) && !strcmp(kobject_name(k),name)) { ret = kobject_get(k); break; } } spin_unlock(&kset->list_lock); return ret; } void subsystem_init(struct subsystem * s) { init_rwsem(&s->rwsem); kset_init(&s->kset); } /** * subsystem_register - register a subsystem. * @s: the subsystem we're registering. * * Once we register the subsystem, we want to make sure that * the kset points back to this subsystem for correct usage of * the rwsem. */ int subsystem_register(struct subsystem * s) { int error; subsystem_init(s); pr_debug("subsystem %s: registering\n",s->kset.kobj.name); if (!(error = kset_add(&s->kset))) { if (!s->kset.subsys) s->kset.subsys = s; } return error; } void subsystem_unregister(struct subsystem * s) { pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name); kset_unregister(&s->kset); } /** * subsystem_create_file - export sysfs attribute file. * @s: subsystem. * @a: subsystem attribute descriptor. */ int subsys_create_file(struct subsystem * s, struct subsys_attribute * a) { int error = 0; if (subsys_get(s)) { error = sysfs_create_file(&s->kset.kobj,&a->attr); subsys_put(s); } return error; } /** * subsystem_remove_file - remove sysfs attribute file. * @s: subsystem. * @a: attribute desciptor. */ void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a) { if (subsys_get(s)) { sysfs_remove_file(&s->kset.kobj,&a->attr); subsys_put(s); } } EXPORT_SYMBOL(kobject_init); EXPORT_SYMBOL(kobject_register); EXPORT_SYMBOL(kobject_unregister); EXPORT_SYMBOL(kobject_get); EXPORT_SYMBOL(kobject_put); EXPORT_SYMBOL(kobject_add); EXPORT_SYMBOL(kobject_del); EXPORT_SYMBOL(kset_register); EXPORT_SYMBOL(kset_unregister); EXPORT_SYMBOL(kset_find_obj); EXPORT_SYMBOL(subsystem_init); EXPORT_SYMBOL(subsystem_register); EXPORT_SYMBOL(subsystem_unregister); EXPORT_SYMBOL(subsys_create_file); EXPORT_SYMBOL(subsys_remove_file);