Commit ca01359a authored by Patrick Mochel's avatar Patrick Mochel

merge

parents fdea9fc9 0de8c962
......@@ -5,7 +5,9 @@ Patrick Mochel <mochel@osdl.org>
30 October 2002
kobjects
1. kobjects
1.1 Description
struct kobject introduces a simple, intregral datatype and a simple
set of semantics for operating on the device. kobjects are intended to
......@@ -13,8 +15,8 @@ be embedded in larger data structures and replace fields it
duplicates. A set of library functions has been developed to assist in
the manipulation of kobjects.
struct kobject looks like this:
1.2 Defintion
struct kobject {
char name[16];
......@@ -26,21 +28,29 @@ struct kobject {
};
void kobject_init(struct kobject *);
int kobject_add(struct kobject *);
int kobject_register(struct kobject *);
void kobject_del(struct kobject *);
void kobject_cleanup(struct kobject *);
void kobject_unregister(struct kobject *);
struct kobject * kobject_get(struct kobject *);
void kobject_put(struct kobject *);
subsystems
2. subsystems
2.1 Description
struct subsystem is introduced to describe a collection of objects of
a certain type. subsystems are kobjects themselves, though they
contain lists of kobjects that belong to that subsystem. Objects of a
subsystem (the embedder objects in which kobjects live) are all of the
same type. The interface looks like:
same type.
2.2 Definition
struct subsystem {
struct kobject kobj;
......@@ -60,6 +70,95 @@ struct subsystem * subsys_get(struct subsystem * s);
void subsys_put(struct subsystem * s);
3. The Interface
The kobject API provides a symmeticral interface that may be used in
one of two ways: by using the default front-end registration
interface, or by directly using the backend helpers the registration
interface uses.
3.1 Default Usage
The default usage is to use kobjet_register() to add a device to the
object hierarchy, and kobject_unregister() to remove it.
kobject_register() will call kobject_init() and kobject_add()
consecutively. kobject_init() will initialize the object and increment
the reference count of the subsystem the object belongs to. It will
leave the reference count of the object at 1.
kobject_add() will insert it into the object hierarchy and create
a sysfs directory for the object. This will increment the reference
count of the object, leaving it at 2.
kobject_unregister() will call kobject_del() and kobject_put()
consecutively. kobject_del() will remove the object from the hierarchy
and the sysfs directory for the object. It will decrement the
reference count for the object. Assuming there are no other users of
the object, it will be left at 1.
kobject_put() will decrement the reference count of the object, and
when it reaches 0, call kobject_cleanup(). This will happen
immediately if there are no other users of the object.
kobject_cleanup() will call the subsystem's release() method
for the object, and decrement the subsystem's reference count.
Because kobject_unregister() calls kobject_put(), instead of
kobject_cleanup() directly, when an object is unregistered, the
pointer to the object is guaranteed to remain valid until the last
reference to the object has gone away.
Users of objects should call kobject_get() to obtain a reference to
the object that they are using. If the object passed to it is a valid
object (i.e. still present in the system), it will return a pointer to
the object. Otherwise, it will return NULL.
When users are done using an object, they should call kobject_put() to
decrement the reference count on the object. As explained above, when
the reference count for the object reaches 0, kobject_cleanup() will
be called for the object.
3.2 Backend Usage
Users of the kobject infrastructure may use the backend functions
directly. In order to maintain consistency and reduce confusion, users
of the interface should use only the front end registration-oriented
interface, or the backend helpers.
Using the backend helpers allows code to use the kobjects solely for
the reference counting and garbage collection mechanisms, and
optionally adding them to the object hierarchy or exporting them via
sysfs.
To take advantage of this side of the interface, users should call
kobject_init() to initialize the object. As stated above, this will
leave the reference count of the object at 1, and will enable the
subsystem to use the reference count of the object.
When the life of the object is ending, the kobject_put() should be
called to decrement the reference count of the object. Just like
above, this will call kobject_cleanup() when the reference count
reaches 0, and release() method of the object's subsystem will be
called.
During the lifetime of the object, kobject_add() and kobject_del() may
be called to add the object to the hierarchy and export it via
sysfs. kobject_del() must always be called if kobject_add() has
previously been called. Care should be taken to ensure kobject_del()
is called before the final kobject_put() is called, though not doing
so will not cause catastrophe, only confusion when reading the source
code. Fatal results are avoided by having kobject_add() increment the
reference count of the object, for kobject_del() to decrement.
3.3 Summary
Using either interface, users should obtain the same results. The
registration interface does the same actions as the backend interface,
though it guarantees that initialization and addition, and deletion
and cleanup, happen consecutively.
Familial Relations
......@@ -134,21 +233,3 @@ object that registers with them. A subsystem definition may contain a
NULL-terminated array of attributes that will be exported when an
object is registered with the subsystem.
Reference Counting
All objects contain reference counts. All functions accessing objects
should increment the reference count until they are finished, and
decrement the reference count. When an object is initialized, it
receives a reference count of 1. When a device is unregistered, the
reference is decremented. When the reference counts reaches 0, the
subsystem's ->release() callback for that object type (remember
subsystems control only one type of device each) is called; and the
reference counts of the kobject's subsystem and parent are
decremented.
The ->release() callback is the opportunity for the subsystem to free
memory allocated for the object. It is the notification that
absolutely no one is using the structure any more (and can't acquire a
reference to it), so it is safe to free it.
......@@ -19,6 +19,9 @@ extern void bus_remove_driver(struct device_driver *);
extern int devclass_add_device(struct device *);
extern void devclass_remove_device(struct device *);
extern int devclass_add_driver(struct device_driver *);
extern void devclass_remove_driver(struct device_driver *);
extern int interface_add(struct device_class *, struct device *);
extern void interface_remove(struct device_class *, struct device *);
......
......@@ -7,7 +7,7 @@
*
*/
#define DEBUG 0
#undef DEBUG
#include <linux/device.h>
#include <linux/module.h>
......
......@@ -5,7 +5,7 @@
* 2002 Open Source Development Lab
*/
#define DEBUG 0
#undef DEBUG
#include <linux/device.h>
#include <linux/err.h>
......@@ -134,7 +134,7 @@ int device_add(struct device *dev)
devclass_add_device(dev);
register_done:
if (error) {
up(&device_sem);
down(&device_sem);
list_del_init(&dev->g_list);
list_del_init(&dev->node);
up(&device_sem);
......
......@@ -48,7 +48,7 @@ int __init register_cpu(struct cpu *cpu, int num, struct node *root)
static int __init register_cpu_type(void)
{
driver_register(&cpu_driver);
return devclass_register(&cpu_devclass);
devclass_register(&cpu_devclass);
return driver_register(&cpu_driver);
}
postcore_initcall(register_cpu_type);
......@@ -3,7 +3,7 @@
*
*/
#define DEBUG 0
#undef DEBUG
#include <linux/device.h>
#include <linux/module.h>
......@@ -118,6 +118,7 @@ int driver_register(struct device_driver * drv)
INIT_LIST_HEAD(&drv->devices);
drv->present = 1;
bus_add_driver(drv);
devclass_add_driver(drv);
put_driver(drv);
return 0;
}
......@@ -128,6 +129,9 @@ void driver_unregister(struct device_driver * drv)
drv->present = 0;
spin_unlock(&device_lock);
pr_debug("driver %s:%s: unregistering\n",drv->bus->name,drv->name);
bus_remove_driver(drv);
devclass_remove_driver(drv);
kobject_unregister(&drv->kobj);
put_driver(drv);
}
......
......@@ -5,7 +5,7 @@
* 2002 Open Source Development Lab
*/
#define DEBUG 0
#undef DEBUG
#include <linux/device.h>
#include <linux/module.h>
......
......@@ -10,7 +10,7 @@
*
*/
#define DEBUG 0
#undef DEBUG
#include <linux/device.h>
#include <linux/slab.h>
......
......@@ -2,7 +2,7 @@
* intf.c - class-specific interface management
*/
#define DEBUG 1
#undef DEBUG
#include <linux/device.h>
#include <linux/module.h>
......@@ -37,7 +37,7 @@ int interface_register(struct device_interface * intf)
struct device_class * cls = intf->devclass;
if (cls) {
pr_debug("register interface '%s' with class '%s\n",
pr_debug("register interface '%s' with class '%s'\n",
intf->name,cls->name);
kobject_init(&intf->kobj);
strncpy(intf->kobj.name,intf->name,KOBJ_NAME_LEN);
......
......@@ -8,7 +8,7 @@
*
*/
#define DEBUG 0
#undef DEBUG
#include <linux/device.h>
#include <linux/module.h>
......
......@@ -10,7 +10,7 @@
* add themselves as children of the system bus.
*/
#define DEBUG 1
#undef DEBUG
#include <linux/device.h>
#include <linux/err.h>
......
......@@ -23,6 +23,8 @@
* Please see Documentation/filesystems/sysfs.txt for more information.
*/
#undef DEBUG
#include <linux/list.h>
#include <linux/init.h>
#include <linux/pagemap.h>
......@@ -173,17 +175,11 @@ static ssize_t
sysfs_read_file(struct file *file, char *buf, size_t count, loff_t *ppos)
{
struct attribute * attr = file->f_dentry->d_fsdata;
struct sysfs_ops * ops = NULL;
struct kobject * kobj;
struct sysfs_ops * ops = file->private_data;
struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
unsigned char *page;
ssize_t retval = 0;
kobj = file->f_dentry->d_parent->d_fsdata;
if (kobj && kobj->subsys)
ops = kobj->subsys->sysfs_ops;
if (!ops || !ops->show)
return 0;
if (count > PAGE_SIZE)
count = PAGE_SIZE;
......@@ -234,16 +230,11 @@ static ssize_t
sysfs_write_file(struct file *file, const char *buf, size_t count, loff_t *ppos)
{
struct attribute * attr = file->f_dentry->d_fsdata;
struct sysfs_ops * ops = NULL;
struct kobject * kobj;
struct sysfs_ops * ops = file->private_data;
struct kobject * kobj = file->f_dentry->d_parent->d_fsdata;
ssize_t retval = 0;
char * page;
kobj = file->f_dentry->d_parent->d_fsdata;
if (kobj && kobj->subsys)
ops = kobj->subsys->sysfs_ops;
if (!ops || !ops->store)
return -EINVAL;
page = (char *)__get_free_page(GFP_KERNEL);
if (!page)
......@@ -275,21 +266,72 @@ sysfs_write_file(struct file *file, const char *buf, size_t count, loff_t *ppos)
return retval;
}
static int sysfs_open_file(struct inode * inode, struct file * filp)
static int check_perm(struct inode * inode, struct file * file)
{
struct kobject * kobj;
struct kobject * kobj = kobject_get(file->f_dentry->d_parent->d_fsdata);
struct attribute * attr = file->f_dentry->d_fsdata;
struct sysfs_ops * ops = NULL;
int error = 0;
kobj = filp->f_dentry->d_parent->d_fsdata;
if ((kobj = kobject_get(kobj))) {
struct attribute * attr = filp->f_dentry->d_fsdata;
if (!attr)
error = -EINVAL;
} else
if (!kobj || !attr)
goto Einval;
if (kobj->subsys)
ops = kobj->subsys->sysfs_ops;
/* No sysfs operations, either from having no subsystem,
* or the subsystem have no operations.
*/
if (!ops)
goto Eaccess;
/* File needs write support.
* The inode's perms must say it's ok,
* and we must have a store method.
*/
if (file->f_mode & FMODE_WRITE) {
if (!(inode->i_mode & S_IWUGO))
goto Eperm;
if (!ops->store)
goto Eaccess;
}
/* File needs read support.
* The inode's perms must say it's ok, and we there
* must be a show method for it.
*/
if (file->f_mode & FMODE_READ) {
if (!(inode->i_mode & S_IRUGO))
goto Eperm;
if (!ops->show)
goto Eaccess;
}
/* No error? Great, store the ops in file->private_data
* for easy access in the read/write functions.
*/
file->private_data = ops;
goto Done;
Einval:
error = -EINVAL;
goto Done;
Eaccess:
error = -EACCES;
goto Done;
Eperm:
error = -EPERM;
Done:
return error;
}
static int sysfs_open_file(struct inode * inode, struct file * filp)
{
return check_perm(inode,filp);
}
static int sysfs_release(struct inode * inode, struct file * filp)
{
struct kobject * kobj = filp->f_dentry->d_parent->d_fsdata;
......
......@@ -24,6 +24,10 @@ struct kobject {
};
extern void kobject_init(struct kobject *);
extern void kobject_cleanup(struct kobject *);
extern int kobject_add(struct kobject *);
extern void kobject_del(struct kobject *);
extern int kobject_register(struct kobject *);
extern void kobject_unregister(struct kobject *);
......
......@@ -2,15 +2,17 @@
* kobject.c - library routines for handling generic kernel objects
*/
#define DEBUG 0
#undef DEBUG
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/module.h>
#include <linux/stat.h>
static spinlock_t kobj_lock = SPIN_LOCK_UNLOCKED;
/**
* kobject_populate_dir - populate directory with attributes.
* populate_dir - populate directory with attributes.
* @kobj: object we're working on.
*
* Most subsystems have a set of default attributes that
......@@ -21,7 +23,7 @@
*
*/
static int kobject_populate_dir(struct kobject * kobj)
static int populate_dir(struct kobject * kobj)
{
struct subsystem * s = kobj->subsys;
struct attribute * attr;
......@@ -37,6 +39,20 @@ static int kobject_populate_dir(struct kobject * kobj)
return error;
}
static int create_dir(struct kobject * kobj)
{
int error = 0;
if (strlen(kobj->name)) {
error = sysfs_create_dir(kobj);
if (!error) {
if ((error = populate_dir(kobj)))
sysfs_remove_dir(kobj);
}
}
return error;
}
/**
* kobject_init - initialize object.
* @kobj: object in question.
......@@ -46,70 +62,88 @@ void kobject_init(struct kobject * kobj)
{
atomic_set(&kobj->refcount,1);
INIT_LIST_HEAD(&kobj->entry);
kobj->subsys = subsys_get(kobj->subsys);
}
/**
* kobject_register - register an object.
* @kobj: object in question.
*
* For now, fill in the replicated fields in the object's
* directory entry, and create a dir in sysfs.
* This stuff should go away in the future, as we move
* more implicit things to sysfs.
* kobject_add - add an object to the hierarchy.
* @kobj: object.
*/
int kobject_register(struct kobject * kobj)
int kobject_add(struct kobject * kobj)
{
int error = 0;
struct subsystem * s = subsys_get(kobj->subsys);
struct subsystem * s = kobj->subsys;
struct kobject * parent = kobject_get(kobj->parent);
pr_debug("kobject %s: registering\n",kobj->name);
if (parent)
pr_debug(" parent is %s\n",parent->name);
if (!(kobj = kobject_get(kobj)))
return -ENOENT;
pr_debug("kobject %s: registering. parent: %s, subsys: %s\n",
kobj->name, parent ? parent->name : "<NULL>",
kobj->subsys ? kobj->subsys->kobj.name : "<NULL>" );
if (s) {
down_write(&s->rwsem);
if (parent)
list_add_tail(&kobj->entry,&parent->entry);
else {
list_add_tail(&kobj->entry,&s->list);
kobj->parent = &s->kobj;
kobj->parent = kobject_get(&s->kobj);
}
up_write(&s->rwsem);
}
if (strlen(kobj->name)) {
error = sysfs_create_dir(kobj);
if (!error) {
error = kobject_populate_dir(kobj);
error = create_dir(kobj);
if (error && kobj->parent)
kobject_put(kobj->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)
sysfs_remove_dir(kobj);
}
}
kobject_cleanup(kobj);
} else
error = -EINVAL;
return error;
}
/**
* kobject_unregister - unlink an object.
* @kobj: object going away.
*
* The device has been told to be removed, but may
* not necessarily be disappearing from the kernel.
* So, we remove the directory and decrement the refcount
* that we set with kobject_register().
*
* Eventually (maybe now), the refcount will hit 0, and
* put_device() will clean the device up.
* kobject_del - unlink kobject from hierarchy.
* @kobj: object.
*/
void kobject_unregister(struct kobject * kobj)
void kobject_del(struct kobject * kobj)
{
pr_debug("kobject %s: unregistering\n",kobj->name);
sysfs_remove_dir(kobj);
if (kobj->subsys) {
down_write(&kobj->subsys->rwsem);
list_del_init(&kobj->entry);
up_write(&kobj->subsys->rwsem);
}
if (kobj->parent)
kobject_put(kobj->parent);
kobject_put(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",kobj->name);
kobject_del(kobj);
kobject_put(kobj);
}
......@@ -121,45 +155,48 @@ void kobject_unregister(struct kobject * kobj)
struct kobject * kobject_get(struct kobject * kobj)
{
struct kobject * ret = kobj;
spin_lock(&kobj_lock);
if (kobj && atomic_read(&kobj->refcount) > 0)
atomic_inc(&kobj->refcount);
else
ret = NULL;
spin_unlock(&kobj_lock);
return ret;
}
/**
* kobject_put - decrement refcount for object.
* kobject_cleanup - free kobject resources.
* @kobj: object.
*
* Decrement the refcount, and check if 0. If it is, then
* we're gonna need to clean it up, and decrement the refcount
* of its parent.
*
* @kobj->parent could point to its subsystem, which we also
* want to decrement the reference count for. We always dec
* the refcount for the parent, but only do so for the subsystem
* if it points to a different place than the parent.
*/
void kobject_put(struct kobject * kobj)
void kobject_cleanup(struct kobject * kobj)
{
struct kobject * parent = kobj->parent;
struct subsystem * s = kobj->subsys;
if (!atomic_dec_and_test(&kobj->refcount))
return;
pr_debug("kobject %s: cleaning up\n",kobj->name);
if (s) {
down_write(&s->rwsem);
list_del_init(&kobj->entry);
if (s->release)
s->release(kobj);
if (&s->kobj != parent)
up_write(&s->rwsem);
subsys_put(s);
}
}
if (parent)
kobject_put(parent);
/**
* kobject_put - decrement refcount for object.
* @kobj: object.
*
* Decrement the refcount, and if 0, call kobject_cleanup().
*/
void kobject_put(struct kobject * kobj)
{
if (!atomic_dec_and_lock(&kobj->refcount, &kobj_lock))
return;
spin_unlock(&kobj_lock);
kobject_cleanup(kobj);
}
......@@ -180,9 +217,8 @@ int subsystem_register(struct subsystem * s)
subsystem_init(s);
if (s->parent)
s->kobj.parent = &s->parent->kobj;
pr_debug("subsystem %s: registering\n",s->kobj.name);
if (s->parent)
pr_debug(" parent is %s\n",s->parent->kobj.name);
pr_debug("subsystem %s: registering, parent: %s\n",
s->kobj.name,s->parent ? s->parent->kobj.name : "<none>");
return kobject_register(&s->kobj);
}
......
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