Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6

direct expression of inheritance, so other techniques - such as structure

embedding - must be used.

So, for example, the UIO code has a structure that defines the memory

region associated with a uio device:

(As an aside, for those familiar with the kernel linked list implementation,

this is analogous as to how "list_head" structs are rarely useful on

their own, but are invariably found embedded in the larger objects of

interest.)

struct uio_mem {

So, for example, the UIO code in drivers/uio/uio.c has a structure that

defines the memory region associated with a uio device:

    struct uio_map {

	struct kobject kobj;

	unsigned long addr;

	unsigned long size;

	int memtype;

	void __iomem *internal_addr;

	struct uio_mem *mem;

    };

If you have a struct uio_mem structure, finding its embedded kobject is

If you have a struct uio_map structure, finding its embedded kobject is

just a matter of using the kobj member.  Code that works with kobjects will

often have the opposite problem, however: given a struct kobject pointer,

what is the pointer to the containing structure?  You must avoid tricks

    container_of(pointer, type, member)

where pointer is the pointer to the embedded kobject, type is the type of

the containing structure, and member is the name of the structure field to

which pointer points.  The return value from container_of() is a pointer to

the given type. So, for example, a pointer "kp" to a struct kobject

embedded within a struct uio_mem could be converted to a pointer to the

containing uio_mem structure with:

where:

  * "pointer" is the pointer to the embedded kobject,

  * "type" is the type of the containing structure, and

  * "member" is the name of the structure field to which "pointer" points.

The return value from container_of() is a pointer to the corresponding

container type. So, for example, a pointer "kp" to a struct kobject

embedded *within* a struct uio_map could be converted to a pointer to the

*containing* uio_map structure with:

    struct uio_map *u_map = container_of(kp, struct uio_map, kobj);

For convenience, programmers often define a simple macro for "back-casting"

kobject pointers to the containing type.  Exactly this happens in the

earlier drivers/uio/uio.c, as you can see here:

    struct uio_map {

        struct kobject kobj;

        struct uio_mem *mem;

    };

    #define to_map(map) container_of(map, struct uio_map, kobj)

    struct uio_mem *u_mem = container_of(kp, struct uio_mem, kobj);

where the macro argument "map" is a pointer to the struct kobject in

question.  That macro is subsequently invoked with:

Programmers often define a simple macro for "back-casting" kobject pointers

to the containing type.

    struct uio_map *map = to_map(kobj);

Initialization of kobjects

Example code to copy from

For a more complete example of using ksets and kobjects properly, see the

sample/kobject/kset-example.c code.

example programs samples/kobject/{kobject-example.c,kset-example.c},

which will be built as loadable modules if you select CONFIG_SAMPLE_KOBJECT.

 * 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().

 */

 * 'module' symlink which points to the @owner directory

 * in sysfs.

 *

 * Returns &struct device pointer on success, or ERR_PTR() on error.

 *

 * Note: You probably want to use root_device_register().

 */

struct device *__root_device_register(const char *name, struct module *owner)

 * Any further sysfs files that might be required can be created using this

 * pointer.

 *

 * Returns &struct device pointer on success, or ERR_PTR() on error.

 *

 * Note: the struct class passed to this function must have previously

 * been created with a call to class_create().

 */

 * Any further sysfs files that might be required can be created using this

 * pointer.

 *

 * Returns &struct device pointer on success, or ERR_PTR() on error.

 *

 * Note: the struct class passed to this function must have previously

 * been created with a call to class_create().

 */

}

#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE

static ssize_t cpu_probe_store(struct sys_device *dev,

				struct sysdev_attribute *attr,

static ssize_t cpu_probe_store(struct sysdev_class *class,

			       struct sysdev_class_attribute *attr,

			       const char *buf,

			       size_t count)

{

	return arch_cpu_probe(buf, count);

}

static ssize_t cpu_release_store(struct sys_device *dev,

				struct sysdev_attribute *attr,

static ssize_t cpu_release_store(struct sysdev_class *class,

				 struct sysdev_class_attribute *attr,

				 const char *buf,

				 size_t count)

{

	return arch_cpu_release(buf, count);

}

static SYSDEV_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);

static SYSDEV_ATTR(release, S_IWUSR, NULL, cpu_release_store);

static SYSDEV_CLASS_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);

static SYSDEV_CLASS_ATTR(release, S_IWUSR, NULL, cpu_release_store);

#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */

#else /* ... !CONFIG_HOTPLUG_CPU */

/**

 * firmware_timeout_store - set number of seconds to wait for firmware

 * @class: device class pointer

 * @attr: device attribute pointer

 * @buf: buffer to scan for timeout value

 * @count: number of bytes in @buf

 *

	fw_priv = dev_get_drvdata(f_dev);

	fw_priv->fw = fw;

	sysfs_bin_attr_init(&fw_priv->attr_data);

	retval = sysfs_create_bin_file(&f_dev->kobj, &fw_priv->attr_data);

	if (retval) {

		dev_err(device, "%s: sysfs_create_bin_file failed\n", __func__);