linux/drivers/base/class.c
Tejun Heo 58292cbe66 sysfs: make attr namespace interface less convoluted
sysfs ns (namespace) implementation became more convoluted than
necessary while trying to hide ns information from visible interface.
The relatively recent attr ns support is a good example.

* attr ns tag is determined by sysfs_ops->namespace() callback while
  dir tag is determined by kobj_type->namespace().  The placement is
  arbitrary.

* Instead of performing operations with explicit ns tag, the namespace
  callback is routed through sysfs_attr_ns(), sysfs_ops->namespace(),
  class_attr_namespace(), class_attr->namespace().  It's not simpler
  in any sense.  The only thing this convolution does is traversing
  the whole stack backwards.

The namespace callbacks are unncessary because the operations involved
are inherently synchronous.  The information can be provided in in
straight-forward top-down direction and reversing that direction is
unnecessary and against basic design principles.

This backward interface is unnecessarily convoluted and hinders
properly separating out sysfs from driver model / kobject for proper
layering.  This patch updates attr ns support such that

* sysfs_ops->namespace() and class_attr->namespace() are dropped.

* sysfs_{create|remove}_file_ns(), which take explicit @ns param, are
  added and sysfs_{create|remove}_file() are now simple wrappers
  around the ns aware functions.

* ns handling is dropped from sysfs_chmod_file().  Nobody uses it at
  this point.  sysfs_chmod_file_ns() can be added later if necessary.

* Explicit @ns is propagated through class_{create|remove}_file_ns()
  and netdev_class_{create|remove}_file_ns().

* driver/net/bonding which is currently the only user of attr
  namespace is updated to use netdev_class_{create|remove}_file_ns()
  with @bh->net as the ns tag instead of using the namespace callback.

This patch should be an equivalent conversion without any functional
difference.  It makes the code easier to follow, reduces lines of code
a bit and helps proper separation and layering.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kay Sievers <kay@vrfy.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-09-26 14:50:01 -07:00

599 lines
15 KiB
C

/*
* class.c - basic device class management
*
* Copyright (c) 2002-3 Patrick Mochel
* Copyright (c) 2002-3 Open Source Development Labs
* Copyright (c) 2003-2004 Greg Kroah-Hartman
* Copyright (c) 2003-2004 IBM Corp.
*
* This file is released under the GPLv2
*
*/
#include <linux/device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/kdev_t.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/genhd.h>
#include <linux/mutex.h>
#include "base.h"
#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
char *buf)
{
struct class_attribute *class_attr = to_class_attr(attr);
struct subsys_private *cp = to_subsys_private(kobj);
ssize_t ret = -EIO;
if (class_attr->show)
ret = class_attr->show(cp->class, class_attr, buf);
return ret;
}
static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
const char *buf, size_t count)
{
struct class_attribute *class_attr = to_class_attr(attr);
struct subsys_private *cp = to_subsys_private(kobj);
ssize_t ret = -EIO;
if (class_attr->store)
ret = class_attr->store(cp->class, class_attr, buf, count);
return ret;
}
static void class_release(struct kobject *kobj)
{
struct subsys_private *cp = to_subsys_private(kobj);
struct class *class = cp->class;
pr_debug("class '%s': release.\n", class->name);
if (class->class_release)
class->class_release(class);
else
pr_debug("class '%s' does not have a release() function, "
"be careful\n", class->name);
kfree(cp);
}
static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
{
struct subsys_private *cp = to_subsys_private(kobj);
struct class *class = cp->class;
return class->ns_type;
}
static const struct sysfs_ops class_sysfs_ops = {
.show = class_attr_show,
.store = class_attr_store,
};
static struct kobj_type class_ktype = {
.sysfs_ops = &class_sysfs_ops,
.release = class_release,
.child_ns_type = class_child_ns_type,
};
/* Hotplug events for classes go to the class subsys */
static struct kset *class_kset;
int class_create_file_ns(struct class *cls, const struct class_attribute *attr,
const void *ns)
{
int error;
if (cls)
error = sysfs_create_file_ns(&cls->p->subsys.kobj,
&attr->attr, ns);
else
error = -EINVAL;
return error;
}
void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
const void *ns)
{
if (cls)
sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
}
static struct class *class_get(struct class *cls)
{
if (cls)
kset_get(&cls->p->subsys);
return cls;
}
static void class_put(struct class *cls)
{
if (cls)
kset_put(&cls->p->subsys);
}
static int add_class_attrs(struct class *cls)
{
int i;
int error = 0;
if (cls->class_attrs) {
for (i = 0; cls->class_attrs[i].attr.name; i++) {
error = class_create_file(cls, &cls->class_attrs[i]);
if (error)
goto error;
}
}
done:
return error;
error:
while (--i >= 0)
class_remove_file(cls, &cls->class_attrs[i]);
goto done;
}
static void remove_class_attrs(struct class *cls)
{
int i;
if (cls->class_attrs) {
for (i = 0; cls->class_attrs[i].attr.name; i++)
class_remove_file(cls, &cls->class_attrs[i]);
}
}
static void klist_class_dev_get(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_class);
get_device(dev);
}
static void klist_class_dev_put(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_class);
put_device(dev);
}
int __class_register(struct class *cls, struct lock_class_key *key)
{
struct subsys_private *cp;
int error;
pr_debug("device class '%s': registering\n", cls->name);
cp = kzalloc(sizeof(*cp), GFP_KERNEL);
if (!cp)
return -ENOMEM;
klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
INIT_LIST_HEAD(&cp->interfaces);
kset_init(&cp->glue_dirs);
__mutex_init(&cp->mutex, "subsys mutex", key);
error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
if (error) {
kfree(cp);
return error;
}
/* set the default /sys/dev directory for devices of this class */
if (!cls->dev_kobj)
cls->dev_kobj = sysfs_dev_char_kobj;
#if defined(CONFIG_BLOCK)
/* let the block class directory show up in the root of sysfs */
if (!sysfs_deprecated || cls != &block_class)
cp->subsys.kobj.kset = class_kset;
#else
cp->subsys.kobj.kset = class_kset;
#endif
cp->subsys.kobj.ktype = &class_ktype;
cp->class = cls;
cls->p = cp;
error = kset_register(&cp->subsys);
if (error) {
kfree(cp);
return error;
}
error = add_class_attrs(class_get(cls));
class_put(cls);
return error;
}
EXPORT_SYMBOL_GPL(__class_register);
void class_unregister(struct class *cls)
{
pr_debug("device class '%s': unregistering\n", cls->name);
remove_class_attrs(cls);
kset_unregister(&cls->p->subsys);
}
static void class_create_release(struct class *cls)
{
pr_debug("%s called for %s\n", __func__, cls->name);
kfree(cls);
}
/**
* class_create - create a struct class structure
* @owner: pointer to the module that is to "own" this struct class
* @name: pointer to a string for the name of this class.
* @key: the lock_class_key for this class; used by mutex lock debugging
*
* This is used to create a struct class pointer that can then be used
* in calls to device_create().
*
* Returns &struct class pointer on success, or ERR_PTR() on error.
*
* Note, the pointer created here is to be destroyed when finished by
* making a call to class_destroy().
*/
struct class *__class_create(struct module *owner, const char *name,
struct lock_class_key *key)
{
struct class *cls;
int retval;
cls = kzalloc(sizeof(*cls), GFP_KERNEL);
if (!cls) {
retval = -ENOMEM;
goto error;
}
cls->name = name;
cls->owner = owner;
cls->class_release = class_create_release;
retval = __class_register(cls, key);
if (retval)
goto error;
return cls;
error:
kfree(cls);
return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(__class_create);
/**
* class_destroy - destroys a struct class structure
* @cls: pointer to the struct class that is to be destroyed
*
* Note, the pointer to be destroyed must have been created with a call
* to class_create().
*/
void class_destroy(struct class *cls)
{
if ((cls == NULL) || (IS_ERR(cls)))
return;
class_unregister(cls);
}
/**
* class_dev_iter_init - initialize class device iterator
* @iter: class iterator to initialize
* @class: the class we wanna iterate over
* @start: the device to start iterating from, if any
* @type: device_type of the devices to iterate over, NULL for all
*
* Initialize class iterator @iter such that it iterates over devices
* of @class. If @start is set, the list iteration will start there,
* otherwise if it is NULL, the iteration starts at the beginning of
* the list.
*/
void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
struct device *start, const struct device_type *type)
{
struct klist_node *start_knode = NULL;
if (start)
start_knode = &start->knode_class;
klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
iter->type = type;
}
EXPORT_SYMBOL_GPL(class_dev_iter_init);
/**
* class_dev_iter_next - iterate to the next device
* @iter: class iterator to proceed
*
* Proceed @iter to the next device and return it. Returns NULL if
* iteration is complete.
*
* The returned device is referenced and won't be released till
* iterator is proceed to the next device or exited. The caller is
* free to do whatever it wants to do with the device including
* calling back into class code.
*/
struct device *class_dev_iter_next(struct class_dev_iter *iter)
{
struct klist_node *knode;
struct device *dev;
while (1) {
knode = klist_next(&iter->ki);
if (!knode)
return NULL;
dev = container_of(knode, struct device, knode_class);
if (!iter->type || iter->type == dev->type)
return dev;
}
}
EXPORT_SYMBOL_GPL(class_dev_iter_next);
/**
* class_dev_iter_exit - finish iteration
* @iter: class iterator to finish
*
* Finish an iteration. Always call this function after iteration is
* complete whether the iteration ran till the end or not.
*/
void class_dev_iter_exit(struct class_dev_iter *iter)
{
klist_iter_exit(&iter->ki);
}
EXPORT_SYMBOL_GPL(class_dev_iter_exit);
/**
* class_for_each_device - device iterator
* @class: the class we're iterating
* @start: the device to start with in the list, if any.
* @data: data for the callback
* @fn: function to be called for each device
*
* Iterate over @class's list of devices, and call @fn for each,
* passing it @data. If @start is set, the list iteration will start
* there, otherwise if it is NULL, the iteration starts at the
* beginning of the list.
*
* We check the return of @fn each time. If it returns anything
* other than 0, we break out and return that value.
*
* @fn is allowed to do anything including calling back into class
* code. There's no locking restriction.
*/
int class_for_each_device(struct class *class, struct device *start,
void *data, int (*fn)(struct device *, void *))
{
struct class_dev_iter iter;
struct device *dev;
int error = 0;
if (!class)
return -EINVAL;
if (!class->p) {
WARN(1, "%s called for class '%s' before it was initialized",
__func__, class->name);
return -EINVAL;
}
class_dev_iter_init(&iter, class, start, NULL);
while ((dev = class_dev_iter_next(&iter))) {
error = fn(dev, data);
if (error)
break;
}
class_dev_iter_exit(&iter);
return error;
}
EXPORT_SYMBOL_GPL(class_for_each_device);
/**
* class_find_device - device iterator for locating a particular device
* @class: the class we're iterating
* @start: Device to begin with
* @data: data for the match function
* @match: function to check device
*
* This is similar to the class_for_each_dev() function above, but it
* returns a reference to a device that is 'found' for later use, as
* determined by the @match callback.
*
* The callback should return 0 if the device doesn't match and non-zero
* if it does. If the callback returns non-zero, this function will
* return to the caller and not iterate over any more devices.
*
* Note, you will need to drop the reference with put_device() after use.
*
* @fn is allowed to do anything including calling back into class
* code. There's no locking restriction.
*/
struct device *class_find_device(struct class *class, struct device *start,
const void *data,
int (*match)(struct device *, const void *))
{
struct class_dev_iter iter;
struct device *dev;
if (!class)
return NULL;
if (!class->p) {
WARN(1, "%s called for class '%s' before it was initialized",
__func__, class->name);
return NULL;
}
class_dev_iter_init(&iter, class, start, NULL);
while ((dev = class_dev_iter_next(&iter))) {
if (match(dev, data)) {
get_device(dev);
break;
}
}
class_dev_iter_exit(&iter);
return dev;
}
EXPORT_SYMBOL_GPL(class_find_device);
int class_interface_register(struct class_interface *class_intf)
{
struct class *parent;
struct class_dev_iter iter;
struct device *dev;
if (!class_intf || !class_intf->class)
return -ENODEV;
parent = class_get(class_intf->class);
if (!parent)
return -EINVAL;
mutex_lock(&parent->p->mutex);
list_add_tail(&class_intf->node, &parent->p->interfaces);
if (class_intf->add_dev) {
class_dev_iter_init(&iter, parent, NULL, NULL);
while ((dev = class_dev_iter_next(&iter)))
class_intf->add_dev(dev, class_intf);
class_dev_iter_exit(&iter);
}
mutex_unlock(&parent->p->mutex);
return 0;
}
void class_interface_unregister(struct class_interface *class_intf)
{
struct class *parent = class_intf->class;
struct class_dev_iter iter;
struct device *dev;
if (!parent)
return;
mutex_lock(&parent->p->mutex);
list_del_init(&class_intf->node);
if (class_intf->remove_dev) {
class_dev_iter_init(&iter, parent, NULL, NULL);
while ((dev = class_dev_iter_next(&iter)))
class_intf->remove_dev(dev, class_intf);
class_dev_iter_exit(&iter);
}
mutex_unlock(&parent->p->mutex);
class_put(parent);
}
ssize_t show_class_attr_string(struct class *class,
struct class_attribute *attr, char *buf)
{
struct class_attribute_string *cs;
cs = container_of(attr, struct class_attribute_string, attr);
return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
}
EXPORT_SYMBOL_GPL(show_class_attr_string);
struct class_compat {
struct kobject *kobj;
};
/**
* class_compat_register - register a compatibility class
* @name: the name of the class
*
* Compatibility class are meant as a temporary user-space compatibility
* workaround when converting a family of class devices to a bus devices.
*/
struct class_compat *class_compat_register(const char *name)
{
struct class_compat *cls;
cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
if (!cls)
return NULL;
cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
if (!cls->kobj) {
kfree(cls);
return NULL;
}
return cls;
}
EXPORT_SYMBOL_GPL(class_compat_register);
/**
* class_compat_unregister - unregister a compatibility class
* @cls: the class to unregister
*/
void class_compat_unregister(struct class_compat *cls)
{
kobject_put(cls->kobj);
kfree(cls);
}
EXPORT_SYMBOL_GPL(class_compat_unregister);
/**
* class_compat_create_link - create a compatibility class device link to
* a bus device
* @cls: the compatibility class
* @dev: the target bus device
* @device_link: an optional device to which a "device" link should be created
*/
int class_compat_create_link(struct class_compat *cls, struct device *dev,
struct device *device_link)
{
int error;
error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
if (error)
return error;
/*
* Optionally add a "device" link (typically to the parent), as a
* class device would have one and we want to provide as much
* backwards compatibility as possible.
*/
if (device_link) {
error = sysfs_create_link(&dev->kobj, &device_link->kobj,
"device");
if (error)
sysfs_remove_link(cls->kobj, dev_name(dev));
}
return error;
}
EXPORT_SYMBOL_GPL(class_compat_create_link);
/**
* class_compat_remove_link - remove a compatibility class device link to
* a bus device
* @cls: the compatibility class
* @dev: the target bus device
* @device_link: an optional device to which a "device" link was previously
* created
*/
void class_compat_remove_link(struct class_compat *cls, struct device *dev,
struct device *device_link)
{
if (device_link)
sysfs_remove_link(&dev->kobj, "device");
sysfs_remove_link(cls->kobj, dev_name(dev));
}
EXPORT_SYMBOL_GPL(class_compat_remove_link);
int __init classes_init(void)
{
class_kset = kset_create_and_add("class", NULL, NULL);
if (!class_kset)
return -ENOMEM;
return 0;
}
EXPORT_SYMBOL_GPL(class_create_file_ns);
EXPORT_SYMBOL_GPL(class_remove_file_ns);
EXPORT_SYMBOL_GPL(class_unregister);
EXPORT_SYMBOL_GPL(class_destroy);
EXPORT_SYMBOL_GPL(class_interface_register);
EXPORT_SYMBOL_GPL(class_interface_unregister);