Re: [PATCH 1/4] driver core: add root_device_register()

Re: [PATCH 1/4] driver core: add root_device_register()

[Cornelia Huck]

On Thu, 11 Dec 2008 16:16:53 +0000,
Mark McLoughlin <markmc@redhat.com> wrote:

> Add support for allocating root device objects which group
> device objects under /sys/devices directories.
> 
> Also add a sysfs 'module' symlink which points to the owner
> of the root device object. This will be used in virtio to
> allow userspace to determine which virtio bus implementation
> a given device is associated with.

I was just hacking up a similar patch :)

> 
> Signed-off-by: Mark McLoughlin <markmc@redhat.com>
> ---
>  drivers/base/core.c    |   88 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/device.h |   11 ++++++
>  2 files changed, 99 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 8c2cc26..db160a2 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1196,6 +1196,94 @@ EXPORT_SYMBOL_GPL(put_device);
>  EXPORT_SYMBOL_GPL(device_create_file);
>  EXPORT_SYMBOL_GPL(device_remove_file);
> 
> +struct root_device
> +{
> +	struct device dev;
> +	struct module *owner;
> +};
> +
> +static void root_device_release(struct device *dev)
> +{
> +	struct root_device *root = container_of(dev, struct root_device, dev);
> +
> +	if (root->owner)
> +		sysfs_remove_link(&root->dev.kobj, "module");

I'd rather remove the link before you unregister.

> +
> +	kfree(root);
> +}
> +
> +/**
> + * __root_device_register - allocate and register a root device
> + * @name: root device name
> + * @owner: owner module of the root device, usually THIS_MODULE
> + *
> + * This function allocates a root device and registers it
> + * using device_register(). In order to free the returned
> + * device, use root_device_unregister().
> + *
> + * Root devices are dummy devices which allow other devices
> + * to be grouped under /sys/devices. Use this function to
> + * allocate a root device and then use it as the parent of
> + * any device which should appear under /sys/devices/{name}
> + *
> + * The /sys/devices/{name} directory will also contain a
> + * 'module' symlink which points to the @owner directory
> + * in sysfs.

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

> + */
> +struct device *__root_device_register(const char *name, struct module *owner)
> +{
> +	struct root_device *root;
> +	int err = -ENOMEM;
> +
> +	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
> +	if (!root)
> +		return ERR_PTR(err);
> +
> +	err = dev_set_name(&root->dev, name);
> +	if (err) {
> +		kfree(root);
> +		return ERR_PTR(err);
> +	}
> +
> +	root->dev.release = root_device_release;
> +
> +	err = device_register(&root->dev);
> +	if (err) {
> +		put_device(&root->dev);
> +		return ERR_PTR(err);
> +	}
> +
> +	if (owner) {
> +		struct module_kobject *mk = &owner->mkobj;
> +
> +		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
> +		if (err) {;

Stray ';'

> +			device_unregister(&root->dev);
> +			return ERR_PTR(err);
> +		}
> +		root->owner = owner;
> +	}
> +
> +	return &root->dev;
> +}
> +EXPORT_SYMBOL_GPL(__root_device_register);
> +
> +/**
> + * root_device_unregister - unregister and free a root device
> + * @root: device going away.
> + *
> + * We simply release @root using device_unregister(). If @root
> + * has a reference count of one, the device will be freed
> + * after it has been unregistered. Otherwise, the structure
> + * will stick around until the final reference is dropped
> + * using put_device().

I don't think you'll need to explain device handling here. How about
this:

root_device_unregister - unregister a root device
@root: device going away

This function unregisters and cleans up a device that was created by
root_device_register().

> + */
> +void root_device_unregister(struct device *root)
> +{

Clean up the symlink here.

> +	device_unregister(root);
> +}
> +EXPORT_SYMBOL_GPL(root_device_unregister);
> +
> 
>  static void device_create_release(struct device *dev)
>  {
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 1a3686d..9e02980 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -483,6 +483,17 @@ extern int device_rename(struct device *dev, char *new_name);
>  extern int device_move(struct device *dev, struct device *new_parent);
> 
>  /*
> + * Root device objects for grouping under /sys/devices
> + */
> +extern struct device *__root_device_register(const char *name,
> +					     struct module *owner);
> +static inline struct device *root_device_register(const char *name)
> +{
> +	return __root_device_register(name, THIS_MODULE);
> +}
> +extern void root_device_unregister(struct device *root);
> +
> +/*
>   * Manual binding of a device to driver. See drivers/base/bus.c
>   * for information on use.
>   */
> -- 
> 1.5.4.3
> 

Re: [PATCH 4/4] s390: remove s390_root_dev_*()

[Cornelia Huck]

(adding cc:s)

On Thu, 11 Dec 2008 16:16:56 +0000,
Mark McLoughlin <markmc@redhat.com> wrote:

> Replace s390_root_dev_register() with root_device_register() etc.

Nice, one more special case generalized :) I'll give it a run.

> 
> Signed-off-by: Mark McLoughlin <markmc@redhat.com>
> ---
>  arch/s390/include/asm/s390_rdev.h |   15 -----------
>  drivers/s390/Makefile             |    2 +-
>  drivers/s390/block/dcssblk.c      |   11 +++----
>  drivers/s390/crypto/ap_bus.c      |    7 ++---
>  drivers/s390/kvm/kvm_virtio.c     |    5 +--
>  drivers/s390/net/cu3088.c         |    7 ++---
>  drivers/s390/net/qeth_core_main.c |    7 ++---
>  drivers/s390/net/qeth_l2_main.c   |    2 -
>  drivers/s390/net/qeth_l3_main.c   |    2 -
>  drivers/s390/s390_rdev.c          |   51 -------------------------------------
>  net/iucv/iucv.c                   |    5 +--
>  11 files changed, 19 insertions(+), 95 deletions(-)
>  delete mode 100644 arch/s390/include/asm/s390_rdev.h
>  delete mode 100644 drivers/s390/s390_rdev.c
> 
> diff --git a/arch/s390/include/asm/s390_rdev.h b/arch/s390/include/asm/s390_rdev.h
> deleted file mode 100644
> index 6fa2044..0000000
> --- a/arch/s390/include/asm/s390_rdev.h
> +++ /dev/null
> @@ -1,15 +0,0 @@
> -/*
> - *  include/asm-s390/ccwdev.h
> - *
> - *    Copyright (C) 2002,2005 IBM Deutschland Entwicklung GmbH, IBM Corporation
> - *    Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
> - *               Carsten Otte  <cotte@de.ibm.com>
> - *
> - *  Interface for s390 root device
> - */
> -
> -#ifndef _S390_RDEV_H_
> -#define _S390_RDEV_H_
> -extern struct device *s390_root_dev_register(const char *);
> -extern void s390_root_dev_unregister(struct device *);
> -#endif /* _S390_RDEV_H_ */
> diff --git a/drivers/s390/Makefile b/drivers/s390/Makefile
> index 4f4e7cf..d0eae59 100644
> --- a/drivers/s390/Makefile
> +++ b/drivers/s390/Makefile
> @@ -4,7 +4,7 @@
> 
>  CFLAGS_sysinfo.o += -Iinclude/math-emu -Iarch/s390/math-emu -w
> 
> -obj-y += s390mach.o sysinfo.o s390_rdev.o
> +obj-y += s390mach.o sysinfo.o
>  obj-y += cio/ block/ char/ crypto/ net/ scsi/ kvm/
> 
>  drivers-y += drivers/s390/built-in.o
> diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
> index 63f26a1..20fca50 100644
> --- a/drivers/s390/block/dcssblk.c
> +++ b/drivers/s390/block/dcssblk.c
> @@ -15,7 +15,6 @@
>  #include <asm/io.h>
>  #include <linux/completion.h>
>  #include <linux/interrupt.h>
> -#include <asm/s390_rdev.h>
> 
>  //#define DCSSBLK_DEBUG		/* Debug messages on/off */
>  #define DCSSBLK_NAME "dcssblk"
> @@ -951,7 +950,7 @@ dcssblk_check_params(void)
>  static void __exit
>  dcssblk_exit(void)
>  {
> -	s390_root_dev_unregister(dcssblk_root_dev);
> +	root_device_unregister(dcssblk_root_dev);
>  	unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
>  }
> 
> @@ -960,22 +959,22 @@ dcssblk_init(void)
>  {
>  	int rc;
> 
> -	dcssblk_root_dev = s390_root_dev_register("dcssblk");
> +	dcssblk_root_dev = root_device_register("dcssblk");
>  	if (IS_ERR(dcssblk_root_dev))
>  		return PTR_ERR(dcssblk_root_dev);
>  	rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
>  	if (rc) {
> -		s390_root_dev_unregister(dcssblk_root_dev);
> +		root_device_unregister(dcssblk_root_dev);
>  		return rc;
>  	}
>  	rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
>  	if (rc) {
> -		s390_root_dev_unregister(dcssblk_root_dev);
> +		root_device_unregister(dcssblk_root_dev);
>  		return rc;
>  	}
>  	rc = register_blkdev(0, DCSSBLK_NAME);
>  	if (rc < 0) {
> -		s390_root_dev_unregister(dcssblk_root_dev);
> +		root_device_unregister(dcssblk_root_dev);
>  		return rc;
>  	}
>  	dcssblk_major = rc;
> diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
> index e3fe683..0689c22 100644
> --- a/drivers/s390/crypto/ap_bus.c
> +++ b/drivers/s390/crypto/ap_bus.c
> @@ -32,7 +32,6 @@
>  #include <linux/notifier.h>
>  #include <linux/kthread.h>
>  #include <linux/mutex.h>
> -#include <asm/s390_rdev.h>
>  #include <asm/reset.h>
>  #include <linux/hrtimer.h>
>  #include <linux/ktime.h>
> @@ -1358,7 +1357,7 @@ int __init ap_module_init(void)
>  	}
> 
>  	/* Create /sys/devices/ap. */
> -	ap_root_device = s390_root_dev_register("ap");
> +	ap_root_device = root_device_register("ap");
>  	rc = IS_ERR(ap_root_device) ? PTR_ERR(ap_root_device) : 0;
>  	if (rc)
>  		goto out_bus;
> @@ -1401,7 +1400,7 @@ out_work:
>  	hrtimer_cancel(&ap_poll_timer);
>  	destroy_workqueue(ap_work_queue);
>  out_root:
> -	s390_root_dev_unregister(ap_root_device);
> +	root_device_unregister(ap_root_device);
>  out_bus:
>  	while (i--)
>  		bus_remove_file(&ap_bus_type, ap_bus_attrs[i]);
> @@ -1432,7 +1431,7 @@ void ap_module_exit(void)
>  	hrtimer_cancel(&ap_poll_timer);
>  	destroy_workqueue(ap_work_queue);
>  	tasklet_kill(&ap_tasklet);
> -	s390_root_dev_unregister(ap_root_device);
> +	root_device_unregister(ap_root_device);
>  	while ((dev = bus_find_device(&ap_bus_type, NULL, NULL,
>  		    __ap_match_all)))
>  	{
> diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
> index c79cf05..db61252 100644
> --- a/drivers/s390/kvm/kvm_virtio.c
> +++ b/drivers/s390/kvm/kvm_virtio.c
> @@ -24,7 +24,6 @@
>  #include <asm/kvm_virtio.h>
>  #include <asm/setup.h>
>  #include <asm/s390_ext.h>
> -#include <asm/s390_rdev.h>
> 
>  #define VIRTIO_SUBCODE_64 0x0D00
> 
> @@ -335,7 +334,7 @@ static int __init kvm_devices_init(void)
>  	if (!MACHINE_IS_KVM)
>  		return -ENODEV;
> 
> -	kvm_root = s390_root_dev_register("kvm_s390");
> +	kvm_root = root_device_register("kvm_s390");
>  	if (IS_ERR(kvm_root)) {
>  		rc = PTR_ERR(kvm_root);
>  		printk(KERN_ERR "Could not register kvm_s390 root device");
> @@ -344,7 +343,7 @@ static int __init kvm_devices_init(void)
> 
>  	rc = vmem_add_mapping(real_memory_size, PAGE_SIZE);
>  	if (rc) {
> -		s390_root_dev_unregister(kvm_root);
> +		root_device_unregister(kvm_root);
>  		return rc;
>  	}
> 
> diff --git a/drivers/s390/net/cu3088.c b/drivers/s390/net/cu3088.c
> index f4a3237..4838345 100644
> --- a/drivers/s390/net/cu3088.c
> +++ b/drivers/s390/net/cu3088.c
> @@ -25,7 +25,6 @@
>  #include <linux/module.h>
>  #include <linux/err.h>
> 
> -#include <asm/s390_rdev.h>
>  #include <asm/ccwdev.h>
>  #include <asm/ccwgroup.h>
> 
> @@ -120,12 +119,12 @@ cu3088_init (void)
>  {
>  	int rc;
> 
> -	cu3088_root_dev = s390_root_dev_register("cu3088");
> +	cu3088_root_dev = root_device_register("cu3088");
>  	if (IS_ERR(cu3088_root_dev))
>  		return PTR_ERR(cu3088_root_dev);
>  	rc = ccw_driver_register(&cu3088_driver);
>  	if (rc)
> -		s390_root_dev_unregister(cu3088_root_dev);
> +		root_device_unregister(cu3088_root_dev);
> 
>  	return rc;
>  }
> @@ -134,7 +133,7 @@ static void __exit
>  cu3088_exit (void)
>  {
>  	ccw_driver_unregister(&cu3088_driver);
> -	s390_root_dev_unregister(cu3088_root_dev);
> +	root_device_unregister(cu3088_root_dev);
>  }
> 
>  MODULE_DEVICE_TABLE(ccw,cu3088_ids);
> diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
> index 52d2659..ffeb47b 100644
> --- a/drivers/s390/net/qeth_core_main.c
> +++ b/drivers/s390/net/qeth_core_main.c
> @@ -21,7 +21,6 @@
> 
>  #include <asm/ebcdic.h>
>  #include <asm/io.h>
> -#include <asm/s390_rdev.h>
> 
>  #include "qeth_core.h"
>  #include "qeth_core_offl.h"
> @@ -4465,7 +4464,7 @@ static int __init qeth_core_init(void)
>  				&driver_attr_group);
>  	if (rc)
>  		goto driver_err;
> -	qeth_core_root_dev = s390_root_dev_register("qeth");
> +	qeth_core_root_dev = root_device_register("qeth");
>  	rc = IS_ERR(qeth_core_root_dev) ? PTR_ERR(qeth_core_root_dev) : 0;
>  	if (rc)
>  		goto register_err;
> @@ -4479,7 +4478,7 @@ static int __init qeth_core_init(void)
> 
>  	return 0;
>  slab_err:
> -	s390_root_dev_unregister(qeth_core_root_dev);
> +	root_device_unregister(qeth_core_root_dev);
>  register_err:
>  	driver_remove_file(&qeth_core_ccwgroup_driver.driver,
>  			   &driver_attr_group);
> @@ -4496,7 +4495,7 @@ out_err:
> 
>  static void __exit qeth_core_exit(void)
>  {
> -	s390_root_dev_unregister(qeth_core_root_dev);
> +	root_device_unregister(qeth_core_root_dev);
>  	driver_remove_file(&qeth_core_ccwgroup_driver.driver,
>  			   &driver_attr_group);
>  	ccwgroup_driver_unregister(&qeth_core_ccwgroup_driver);
> diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
> index 1b1e803..33c8fe2 100644
> --- a/drivers/s390/net/qeth_l2_main.c
> +++ b/drivers/s390/net/qeth_l2_main.c
> @@ -17,8 +17,6 @@
>  #include <linux/mii.h>
>  #include <linux/ip.h>
> 
> -#include <asm/s390_rdev.h>
> -
>  #include "qeth_core.h"
>  #include "qeth_core_offl.h"
> 
> diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
> index ed59fed..5dd2210 100644
> --- a/drivers/s390/net/qeth_l3_main.c
> +++ b/drivers/s390/net/qeth_l3_main.c
> @@ -23,8 +23,6 @@
>  #include <net/ip.h>
>  #include <net/arp.h>
> 
> -#include <asm/s390_rdev.h>
> -
>  #include "qeth_l3.h"
>  #include "qeth_core_offl.h"
> 
> diff --git a/drivers/s390/s390_rdev.c b/drivers/s390/s390_rdev.c
> deleted file mode 100644
> index 64371c0..0000000
> --- a/drivers/s390/s390_rdev.c
> +++ /dev/null
> @@ -1,51 +0,0 @@
> -/*
> - *  drivers/s390/s390_rdev.c
> - *  s390 root device
> - *
> - *    Copyright (C) 2002, 2005 IBM Deutschland Entwicklung GmbH,
> - *			 IBM Corporation
> - *    Author(s): Cornelia Huck (cornelia.huck@de.ibm.com)
> - *		  Carsten Otte  (cotte@de.ibm.com)
> - */
> -
> -#include <linux/slab.h>
> -#include <linux/err.h>
> -#include <linux/device.h>
> -#include <asm/s390_rdev.h>
> -
> -static void
> -s390_root_dev_release(struct device *dev)
> -{
> -	kfree(dev);
> -}
> -
> -struct device *
> -s390_root_dev_register(const char *name)
> -{
> -	struct device *dev;
> -	int ret;
> -
> -	if (!strlen(name))
> -		return ERR_PTR(-EINVAL);
> -	dev = kzalloc(sizeof(struct device), GFP_KERNEL);
> -	if (!dev)
> -		return ERR_PTR(-ENOMEM);
> -	dev_set_name(dev, name);
> -	dev->release = s390_root_dev_release;
> -	ret = device_register(dev);
> -	if (ret) {
> -		kfree(dev);
> -		return ERR_PTR(ret);
> -	}
> -	return dev;
> -}
> -
> -void
> -s390_root_dev_unregister(struct device *dev)
> -{
> -	if (dev)
> -		device_unregister(dev);
> -}
> -
> -EXPORT_SYMBOL(s390_root_dev_register);
> -EXPORT_SYMBOL(s390_root_dev_unregister);
> diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
> index d7b54b5..6314e1b 100644
> --- a/net/iucv/iucv.c
> +++ b/net/iucv/iucv.c
> @@ -47,7 +47,6 @@
>  #include <asm/ebcdic.h>
>  #include <asm/io.h>
>  #include <asm/s390_ext.h>
> -#include <asm/s390_rdev.h>
>  #include <asm/smp.h>
> 
>  /*
> @@ -1609,7 +1608,7 @@ static int __init iucv_init(void)
>  	rc = register_external_interrupt(0x4000, iucv_external_interrupt);
>  	if (rc)
>  		goto out;
> -	iucv_root = s390_root_dev_register("iucv");
> +	iucv_root = root_device_register("iucv");
>  	if (IS_ERR(iucv_root)) {
>  		rc = PTR_ERR(iucv_root);
>  		goto out_int;
> @@ -1653,7 +1652,7 @@ out_free:
>  		kfree(iucv_irq_data[cpu]);
>  		iucv_irq_data[cpu] = NULL;
>  	}
> -	s390_root_dev_unregister(iucv_root);
> +	root_device_unregister(iucv_root);
>  out_int:
>  	unregister_external_interrupt(0x4000, iucv_external_interrupt);
>  out:
> -- 
> 1.5.4.3
> 


-- 
Cornelia Huck
Linux for zSeries Developer
Tel.: +49-7031-16-4837, Mail: cornelia.huck@de.ibm.com

Re: [PATCH 4/4] s390: remove s390_root_dev_*()

[Cornelia Huck]

On Thu, 11 Dec 2008 18:00:25 +0100,
Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> On Thu, 11 Dec 2008 16:16:56 +0000,
> Mark McLoughlin <markmc@redhat.com> wrote:
> 
> > Replace s390_root_dev_register() with root_device_register() etc.
> 
> Nice, one more special case generalized :) I'll give it a run.

You missed one occurrence in iucv (see below); with that patch applied,
everything seems to work as expected, both for root devices created by
built-ins and by modules.

---
 net/iucv/iucv.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-2.6.orig/net/iucv/iucv.c
+++ linux-2.6/net/iucv/iucv.c
@@ -1682,7 +1682,7 @@ static void __exit iucv_exit(void)
 		kfree(iucv_irq_data[cpu]);
 		iucv_irq_data[cpu] = NULL;
 	}
-	s390_root_dev_unregister(iucv_root);
+	root_device_unregister(iucv_root);
 	bus_unregister(&iucv_bus);
 	unregister_external_interrupt(0x4000, iucv_external_interrupt);
 }

Re: [PATCH 4/4] s390: remove s390_root_dev_*()

[Mark McLoughlin]

On Fri, 2008-12-12 at 10:29 +0100, Cornelia Huck wrote:
> On Thu, 11 Dec 2008 18:00:25 +0100,
> Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> > On Thu, 11 Dec 2008 16:16:56 +0000,
> > Mark McLoughlin <markmc@redhat.com> wrote:
> > 
> > > Replace s390_root_dev_register() with root_device_register() etc.
> > 
> > Nice, one more special case generalized :) I'll give it a run.
> 
> You missed one occurrence in iucv (see below);

Oops.

>  with that patch applied,
> everything seems to work as expected, both for root devices created by
> built-ins and by modules.

Thanks,
Mark.

From: Mark McLoughlin <markmc@redhat.com>
Subject: [PATCH] s390: remove s390_root_dev_*()

Replace s390_root_dev_register() with root_device_register() etc.

[Includes fix from Cornelia Huck]

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
---
 arch/s390/include/asm/s390_rdev.h |   15 -----------
 drivers/s390/Makefile             |    2 +-
 drivers/s390/block/dcssblk.c      |   11 +++----
 drivers/s390/crypto/ap_bus.c      |    7 ++---
 drivers/s390/kvm/kvm_virtio.c     |    5 +--
 drivers/s390/net/cu3088.c         |    7 ++---
 drivers/s390/net/qeth_core_main.c |    7 ++---
 drivers/s390/net/qeth_l2_main.c   |    2 -
 drivers/s390/net/qeth_l3_main.c   |    2 -
 drivers/s390/s390_rdev.c          |   51 -------------------------------------
 net/iucv/iucv.c                   |    7 ++---
 11 files changed, 20 insertions(+), 96 deletions(-)
 delete mode 100644 arch/s390/include/asm/s390_rdev.h
 delete mode 100644 drivers/s390/s390_rdev.c

diff --git a/arch/s390/include/asm/s390_rdev.h b/arch/s390/include/asm/s390_rdev.h
deleted file mode 100644
index 6fa2044..0000000
--- a/arch/s390/include/asm/s390_rdev.h
+++ /dev/null
@@ -1,15 +0,0 @@
-/*
- *  include/asm-s390/ccwdev.h
- *
- *    Copyright (C) 2002,2005 IBM Deutschland Entwicklung GmbH, IBM Corporation
- *    Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
- *               Carsten Otte  <cotte@de.ibm.com>
- *
- *  Interface for s390 root device
- */
-
-#ifndef _S390_RDEV_H_
-#define _S390_RDEV_H_
-extern struct device *s390_root_dev_register(const char *);
-extern void s390_root_dev_unregister(struct device *);
-#endif /* _S390_RDEV_H_ */
diff --git a/drivers/s390/Makefile b/drivers/s390/Makefile
index 4f4e7cf..d0eae59 100644
--- a/drivers/s390/Makefile
+++ b/drivers/s390/Makefile
@@ -4,7 +4,7 @@
 
 CFLAGS_sysinfo.o += -Iinclude/math-emu -Iarch/s390/math-emu -w
 
-obj-y += s390mach.o sysinfo.o s390_rdev.o
+obj-y += s390mach.o sysinfo.o
 obj-y += cio/ block/ char/ crypto/ net/ scsi/ kvm/
 
 drivers-y += drivers/s390/built-in.o
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 63f26a1..20fca50 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -15,7 +15,6 @@
 #include <asm/io.h>
 #include <linux/completion.h>
 #include <linux/interrupt.h>
-#include <asm/s390_rdev.h>
 
 //#define DCSSBLK_DEBUG		/* Debug messages on/off */
 #define DCSSBLK_NAME "dcssblk"
@@ -951,7 +950,7 @@ dcssblk_check_params(void)
 static void __exit
 dcssblk_exit(void)
 {
-	s390_root_dev_unregister(dcssblk_root_dev);
+	root_device_unregister(dcssblk_root_dev);
 	unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
 }
 
@@ -960,22 +959,22 @@ dcssblk_init(void)
 {
 	int rc;
 
-	dcssblk_root_dev = s390_root_dev_register("dcssblk");
+	dcssblk_root_dev = root_device_register("dcssblk");
 	if (IS_ERR(dcssblk_root_dev))
 		return PTR_ERR(dcssblk_root_dev);
 	rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
 	if (rc) {
-		s390_root_dev_unregister(dcssblk_root_dev);
+		root_device_unregister(dcssblk_root_dev);
 		return rc;
 	}
 	rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
 	if (rc) {
-		s390_root_dev_unregister(dcssblk_root_dev);
+		root_device_unregister(dcssblk_root_dev);
 		return rc;
 	}
 	rc = register_blkdev(0, DCSSBLK_NAME);
 	if (rc < 0) {
-		s390_root_dev_unregister(dcssblk_root_dev);
+		root_device_unregister(dcssblk_root_dev);
 		return rc;
 	}
 	dcssblk_major = rc;
diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index e3fe683..0689c22 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -32,7 +32,6 @@
 #include <linux/notifier.h>
 #include <linux/kthread.h>
 #include <linux/mutex.h>
-#include <asm/s390_rdev.h>
 #include <asm/reset.h>
 #include <linux/hrtimer.h>
 #include <linux/ktime.h>
@@ -1358,7 +1357,7 @@ int __init ap_module_init(void)
 	}
 
 	/* Create /sys/devices/ap. */
-	ap_root_device = s390_root_dev_register("ap");
+	ap_root_device = root_device_register("ap");
 	rc = IS_ERR(ap_root_device) ? PTR_ERR(ap_root_device) : 0;
 	if (rc)
 		goto out_bus;
@@ -1401,7 +1400,7 @@ out_work:
 	hrtimer_cancel(&ap_poll_timer);
 	destroy_workqueue(ap_work_queue);
 out_root:
-	s390_root_dev_unregister(ap_root_device);
+	root_device_unregister(ap_root_device);
 out_bus:
 	while (i--)
 		bus_remove_file(&ap_bus_type, ap_bus_attrs[i]);
@@ -1432,7 +1431,7 @@ void ap_module_exit(void)
 	hrtimer_cancel(&ap_poll_timer);
 	destroy_workqueue(ap_work_queue);
 	tasklet_kill(&ap_tasklet);
-	s390_root_dev_unregister(ap_root_device);
+	root_device_unregister(ap_root_device);
 	while ((dev = bus_find_device(&ap_bus_type, NULL, NULL,
 		    __ap_match_all)))
 	{
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index c79cf05..db61252 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -24,7 +24,6 @@
 #include <asm/kvm_virtio.h>
 #include <asm/setup.h>
 #include <asm/s390_ext.h>
-#include <asm/s390_rdev.h>
 
 #define VIRTIO_SUBCODE_64 0x0D00
 
@@ -335,7 +334,7 @@ static int __init kvm_devices_init(void)
 	if (!MACHINE_IS_KVM)
 		return -ENODEV;
 
-	kvm_root = s390_root_dev_register("kvm_s390");
+	kvm_root = root_device_register("kvm_s390");
 	if (IS_ERR(kvm_root)) {
 		rc = PTR_ERR(kvm_root);
 		printk(KERN_ERR "Could not register kvm_s390 root device");
@@ -344,7 +343,7 @@ static int __init kvm_devices_init(void)
 
 	rc = vmem_add_mapping(real_memory_size, PAGE_SIZE);
 	if (rc) {
-		s390_root_dev_unregister(kvm_root);
+		root_device_unregister(kvm_root);
 		return rc;
 	}
 
diff --git a/drivers/s390/net/cu3088.c b/drivers/s390/net/cu3088.c
index f4a3237..4838345 100644
--- a/drivers/s390/net/cu3088.c
+++ b/drivers/s390/net/cu3088.c
@@ -25,7 +25,6 @@
 #include <linux/module.h>
 #include <linux/err.h>
 
-#include <asm/s390_rdev.h>
 #include <asm/ccwdev.h>
 #include <asm/ccwgroup.h>
 
@@ -120,12 +119,12 @@ cu3088_init (void)
 {
 	int rc;
 
-	cu3088_root_dev = s390_root_dev_register("cu3088");
+	cu3088_root_dev = root_device_register("cu3088");
 	if (IS_ERR(cu3088_root_dev))
 		return PTR_ERR(cu3088_root_dev);
 	rc = ccw_driver_register(&cu3088_driver);
 	if (rc)
-		s390_root_dev_unregister(cu3088_root_dev);
+		root_device_unregister(cu3088_root_dev);
 
 	return rc;
 }
@@ -134,7 +133,7 @@ static void __exit
 cu3088_exit (void)
 {
 	ccw_driver_unregister(&cu3088_driver);
-	s390_root_dev_unregister(cu3088_root_dev);
+	root_device_unregister(cu3088_root_dev);
 }
 
 MODULE_DEVICE_TABLE(ccw,cu3088_ids);
diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 52d2659..ffeb47b 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -21,7 +21,6 @@
 
 #include <asm/ebcdic.h>
 #include <asm/io.h>
-#include <asm/s390_rdev.h>
 
 #include "qeth_core.h"
 #include "qeth_core_offl.h"
@@ -4465,7 +4464,7 @@ static int __init qeth_core_init(void)
 				&driver_attr_group);
 	if (rc)
 		goto driver_err;
-	qeth_core_root_dev = s390_root_dev_register("qeth");
+	qeth_core_root_dev = root_device_register("qeth");
 	rc = IS_ERR(qeth_core_root_dev) ? PTR_ERR(qeth_core_root_dev) : 0;
 	if (rc)
 		goto register_err;
@@ -4479,7 +4478,7 @@ static int __init qeth_core_init(void)
 
 	return 0;
 slab_err:
-	s390_root_dev_unregister(qeth_core_root_dev);
+	root_device_unregister(qeth_core_root_dev);
 register_err:
 	driver_remove_file(&qeth_core_ccwgroup_driver.driver,
 			   &driver_attr_group);
@@ -4496,7 +4495,7 @@ out_err:
 
 static void __exit qeth_core_exit(void)
 {
-	s390_root_dev_unregister(qeth_core_root_dev);
+	root_device_unregister(qeth_core_root_dev);
 	driver_remove_file(&qeth_core_ccwgroup_driver.driver,
 			   &driver_attr_group);
 	ccwgroup_driver_unregister(&qeth_core_ccwgroup_driver);
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index 1b1e803..33c8fe2 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -17,8 +17,6 @@
 #include <linux/mii.h>
 #include <linux/ip.h>
 
-#include <asm/s390_rdev.h>
-
 #include "qeth_core.h"
 #include "qeth_core_offl.h"
 
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index ed59fed..5dd2210 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -23,8 +23,6 @@
 #include <net/ip.h>
 #include <net/arp.h>
 
-#include <asm/s390_rdev.h>
-
 #include "qeth_l3.h"
 #include "qeth_core_offl.h"
 
diff --git a/drivers/s390/s390_rdev.c b/drivers/s390/s390_rdev.c
deleted file mode 100644
index 64371c0..0000000
--- a/drivers/s390/s390_rdev.c
+++ /dev/null
@@ -1,51 +0,0 @@
-/*
- *  drivers/s390/s390_rdev.c
- *  s390 root device
- *
- *    Copyright (C) 2002, 2005 IBM Deutschland Entwicklung GmbH,
- *			 IBM Corporation
- *    Author(s): Cornelia Huck (cornelia.huck@de.ibm.com)
- *		  Carsten Otte  (cotte@de.ibm.com)
- */
-
-#include <linux/slab.h>
-#include <linux/err.h>
-#include <linux/device.h>
-#include <asm/s390_rdev.h>
-
-static void
-s390_root_dev_release(struct device *dev)
-{
-	kfree(dev);
-}
-
-struct device *
-s390_root_dev_register(const char *name)
-{
-	struct device *dev;
-	int ret;
-
-	if (!strlen(name))
-		return ERR_PTR(-EINVAL);
-	dev = kzalloc(sizeof(struct device), GFP_KERNEL);
-	if (!dev)
-		return ERR_PTR(-ENOMEM);
-	dev_set_name(dev, name);
-	dev->release = s390_root_dev_release;
-	ret = device_register(dev);
-	if (ret) {
-		kfree(dev);
-		return ERR_PTR(ret);
-	}
-	return dev;
-}
-
-void
-s390_root_dev_unregister(struct device *dev)
-{
-	if (dev)
-		device_unregister(dev);
-}
-
-EXPORT_SYMBOL(s390_root_dev_register);
-EXPORT_SYMBOL(s390_root_dev_unregister);
diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
index d7b54b5..22bb67e 100644
--- a/net/iucv/iucv.c
+++ b/net/iucv/iucv.c
@@ -47,7 +47,6 @@
 #include <asm/ebcdic.h>
 #include <asm/io.h>
 #include <asm/s390_ext.h>
-#include <asm/s390_rdev.h>
 #include <asm/smp.h>
 
 /*
@@ -1609,7 +1608,7 @@ static int __init iucv_init(void)
 	rc = register_external_interrupt(0x4000, iucv_external_interrupt);
 	if (rc)
 		goto out;
-	iucv_root = s390_root_dev_register("iucv");
+	iucv_root = root_device_register("iucv");
 	if (IS_ERR(iucv_root)) {
 		rc = PTR_ERR(iucv_root);
 		goto out_int;
@@ -1653,7 +1652,7 @@ out_free:
 		kfree(iucv_irq_data[cpu]);
 		iucv_irq_data[cpu] = NULL;
 	}
-	s390_root_dev_unregister(iucv_root);
+	root_device_unregister(iucv_root);
 out_int:
 	unregister_external_interrupt(0x4000, iucv_external_interrupt);
 out:
@@ -1683,7 +1682,7 @@ static void __exit iucv_exit(void)
 		kfree(iucv_irq_data[cpu]);
 		iucv_irq_data[cpu] = NULL;
 	}
-	s390_root_dev_unregister(iucv_root);
+	root_device_unregister(iucv_root);
 	bus_unregister(&iucv_bus);
 	unregister_external_interrupt(0x4000, iucv_external_interrupt);
 }
-- 
1.6.0.3

Re: [PATCH 4/4] s390: remove s390_root_dev_*()

[Martin Schwidefsky]

On Fri, 2008-12-12 at 09:35 +0000, Mark McLoughlin wrote:
> From: Mark McLoughlin <markmc@redhat.com>
> Subject: [PATCH] s390: remove s390_root_dev_*()
> 
> Replace s390_root_dev_register() with root_device_register() etc.
> 
> [Includes fix from Cornelia Huck]
> 
> Signed-off-by: Mark McLoughlin <markmc@redhat.com>

I can carry the patch in my patch queue. Thanks.

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.

Re: [PATCH 4/4] s390: remove s390_root_dev_*()

[Cornelia Huck]

On Fri, 12 Dec 2008 09:35:46 +0000,
Mark McLoughlin <markmc@redhat.com> wrote:

> From: Mark McLoughlin <markmc@redhat.com>
> Subject: [PATCH] s390: remove s390_root_dev_*()
> 
> Replace s390_root_dev_register() with root_device_register() etc.
> 
> [Includes fix from Cornelia Huck]
> 
> Signed-off-by: Mark McLoughlin <markmc@redhat.com>

Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>

Re: [PATCH 4/4] s390: remove s390_root_dev_*()

[Martin Schwidefsky]

On Fri, 2008-12-12 at 10:45 +0100, Martin Schwidefsky wrote:
> On Fri, 2008-12-12 at 09:35 +0000, Mark McLoughlin wrote:
> > From: Mark McLoughlin <markmc@redhat.com>
> > Subject: [PATCH] s390: remove s390_root_dev_*()
> > 
> > Replace s390_root_dev_register() with root_device_register() etc.
> > 
> > [Includes fix from Cornelia Huck]
> > 
> > Signed-off-by: Mark McLoughlin <markmc@redhat.com>
> 
> I can carry the patch in my patch queue. Thanks.

Oops, this depends on another patch. If the other patch is missing it
doesn't compile.. So I better not add that patch to my queue. It should
be sent together with the patch it depends on.

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.

Re: [PATCH 4/4] s390: remove s390_root_dev_*()

[Greg KH]

On Fri, Dec 12, 2008 at 09:35:46AM +0000, Mark McLoughlin wrote:
> On Fri, 2008-12-12 at 10:29 +0100, Cornelia Huck wrote:
> > On Thu, 11 Dec 2008 18:00:25 +0100,
> > Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> > > On Thu, 11 Dec 2008 16:16:56 +0000,
> > > Mark McLoughlin <markmc@redhat.com> wrote:
> > > 
> > > > Replace s390_root_dev_register() with root_device_register() etc.
> > > 
> > > Nice, one more special case generalized :) I'll give it a run.
> > 
> > You missed one occurrence in iucv (see below);
> 
> Oops.
> 
> >  with that patch applied,
> > everything seems to work as expected, both for root devices created by
> > built-ins and by modules.
> 
> Thanks,
> Mark.
> 
> From: Mark McLoughlin <markmc@redhat.com>
> Subject: [PATCH] s390: remove s390_root_dev_*()
> 
> Replace s390_root_dev_register() with root_device_register() etc.

Can you resend this whole series, I see lots of replacements in this
thread and it would be good to know exactly what I should be
reviewing/applying.

thanks,

greg k-h

Re: [PATCH 2/4] virtio: do not statically allocate root device

[Rusty Russell]

On Monday 15 December 2008 23:28:27 Mark McLoughlin wrote:
> We shouldn't be statically allocating the root device object,
> so dynamically allocate it using root_device_register()
> instead.

This and 3/4 which would normally go through me:

Acked-by: Rusty Russell <rusty@rustcorp.com.au>

Thanks Greg,
Rusty.

Re: [PATCH 1/4] driver core: add root_device_register()

[Mark McLoughlin]

Add support for allocating root device objects which group
device objects under /sys/devices directories.

Also add a sysfs 'module' symlink which points to the owner
of the root device object. This symlink will be used in virtio
to allow userspace to determine which virtio bus implementation
a given device is associated with.

[Includes suggestions from Cornelia Huck]

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
---
 drivers/base/core.c    |   87 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/device.h |   11 ++++++
 2 files changed, 98 insertions(+), 0 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 8c2cc26..20e5825 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1196,6 +1196,93 @@ EXPORT_SYMBOL_GPL(put_device);
 EXPORT_SYMBOL_GPL(device_create_file);
 EXPORT_SYMBOL_GPL(device_remove_file);
 
+struct root_device
+{
+	struct device dev;
+	struct module *owner;
+};
+
+static void root_device_release(struct device *dev)
+{
+	kfree(dev);
+}
+
+/**
+ * __root_device_register - allocate and register a root device
+ * @name: root device name
+ * @owner: owner module of the root device, usually THIS_MODULE
+ *
+ * This function allocates a root device and registers it
+ * using device_register(). In order to free the returned
+ * device, use root_device_unregister().
+ *
+ * Root devices are dummy devices which allow other devices
+ * to be grouped under /sys/devices. Use this function to
+ * allocate a root device and then use it as the parent of
+ * any device which should appear under /sys/devices/{name}
+ *
+ * The /sys/devices/{name} directory will also contain a
+ * 'module' symlink which points to the @owner directory
+ * in sysfs.
+ *
+ * Note: You probably want to use root_device_register().
+ */
+struct device *__root_device_register(const char *name, struct module *owner)
+{
+	struct root_device *root;
+	int err = -ENOMEM;
+
+	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
+	if (!root)
+		return ERR_PTR(err);
+
+	err = dev_set_name(&root->dev, name);
+	if (err) {
+		kfree(root);
+		return ERR_PTR(err);
+	}
+
+	root->dev.release = root_device_release;
+
+	err = device_register(&root->dev);
+	if (err) {
+		put_device(&root->dev);
+		return ERR_PTR(err);
+	}
+
+	if (owner) {
+		struct module_kobject *mk = &owner->mkobj;
+
+		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
+		if (err) {
+			device_unregister(&root->dev);
+			return ERR_PTR(err);
+		}
+		root->owner = owner;
+	}
+
+	return &root->dev;
+}
+EXPORT_SYMBOL_GPL(__root_device_register);
+
+/**
+ * root_device_unregister - unregister and free a root device
+ * @root: device going away.
+ *
+ * This function unregisters and cleans up a device that was created by
+ * root_device_register().
+ */
+void root_device_unregister(struct device *dev)
+{
+	struct root_device *root = container_of(dev, struct root_device, dev);
+
+	if (root->owner)
+		sysfs_remove_link(&root->dev.kobj, "module");
+
+	device_unregister(dev);
+}
+EXPORT_SYMBOL_GPL(root_device_unregister);
+
 
 static void device_create_release(struct device *dev)
 {
diff --git a/include/linux/device.h b/include/linux/device.h
index 1a3686d..9e02980 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -483,6 +483,17 @@ extern int device_rename(struct device *dev, char *new_name);
 extern int device_move(struct device *dev, struct device *new_parent);
 
 /*
+ * Root device objects for grouping under /sys/devices
+ */
+extern struct device *__root_device_register(const char *name,
+					     struct module *owner);
+static inline struct device *root_device_register(const char *name)
+{
+	return __root_device_register(name, THIS_MODULE);
+}
+extern void root_device_unregister(struct device *root);
+
+/*
  * Manual binding of a device to driver. See drivers/base/bus.c
  * for information on use.
  */
-- 
1.5.4.3

Re: [PATCH 1/4] driver core: add root_device_register()

[Cornelia Huck]

On Thu, 11 Dec 2008 18:23:27 +0000,
Mark McLoughlin <markmc@redhat.com> wrote:

> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 8c2cc26..20e5825 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1196,6 +1196,93 @@ EXPORT_SYMBOL_GPL(put_device);
>  EXPORT_SYMBOL_GPL(device_create_file);
>  EXPORT_SYMBOL_GPL(device_remove_file);
> 
> +struct root_device
> +{
> +	struct device dev;
> +	struct module *owner;
> +};
> +
> +static void root_device_release(struct device *dev)
> +{

You need to get the root device here and free that.

> +	kfree(dev);
> +}

Re: [PATCH 1/4] driver core: add root_device_register()

[Mark McLoughlin]

On Fri, 2008-12-12 at 09:42 +0100, Cornelia Huck wrote:
> On Thu, 11 Dec 2008 18:23:27 +0000,
> Mark McLoughlin <markmc@redhat.com> wrote:
> 
> > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > index 8c2cc26..20e5825 100644
> > --- a/drivers/base/core.c
> > +++ b/drivers/base/core.c
> > @@ -1196,6 +1196,93 @@ EXPORT_SYMBOL_GPL(put_device);
> >  EXPORT_SYMBOL_GPL(device_create_file);
> >  EXPORT_SYMBOL_GPL(device_remove_file);
> > 
> > +struct root_device
> > +{
> > +	struct device dev;
> > +	struct module *owner;
> > +};
> > +
> > +static void root_device_release(struct device *dev)
> > +{
> 
> You need to get the root device here and free that.
> 
> > +	kfree(dev);
> > +}

Yeah, I just figured it was a little overkill given the structure
definition is three lines away. Here it is, though.

Cheers,
Mark.

From: Mark McLoughlin <markmc@redhat.com>
Subject: [PATCH] driver core: add root_device_register()

Add support for allocating root device objects which group
device objects under /sys/devices directories.

Also add a sysfs 'module' symlink which points to the owner
of the root device object. This symlink will be used in virtio
to allow userspace to determine which virtio bus implementation
a given device is associated with.

[Includes suggestions from Cornelia Huck]

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
---
 drivers/base/core.c    |   89 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/device.h |   11 ++++++
 2 files changed, 100 insertions(+), 0 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 8c2cc26..05320af 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1196,6 +1196,95 @@ EXPORT_SYMBOL_GPL(put_device);
 EXPORT_SYMBOL_GPL(device_create_file);
 EXPORT_SYMBOL_GPL(device_remove_file);
 
+struct root_device
+{
+	struct device dev;
+	struct module *owner;
+};
+
+#define to_root_device(dev) container_of(dev, struct root_device, dev)
+
+static void root_device_release(struct device *dev)
+{
+	kfree(to_root_device(dev));
+}
+
+/**
+ * __root_device_register - allocate and register a root device
+ * @name: root device name
+ * @owner: owner module of the root device, usually THIS_MODULE
+ *
+ * This function allocates a root device and registers it
+ * using device_register(). In order to free the returned
+ * device, use root_device_unregister().
+ *
+ * Root devices are dummy devices which allow other devices
+ * to be grouped under /sys/devices. Use this function to
+ * allocate a root device and then use it as the parent of
+ * any device which should appear under /sys/devices/{name}
+ *
+ * The /sys/devices/{name} directory will also contain a
+ * 'module' symlink which points to the @owner directory
+ * in sysfs.
+ *
+ * Note: You probably want to use root_device_register().
+ */
+struct device *__root_device_register(const char *name, struct module *owner)
+{
+	struct root_device *root;
+	int err = -ENOMEM;
+
+	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
+	if (!root)
+		return ERR_PTR(err);
+
+	err = dev_set_name(&root->dev, name);
+	if (err) {
+		kfree(root);
+		return ERR_PTR(err);
+	}
+
+	root->dev.release = root_device_release;
+
+	err = device_register(&root->dev);
+	if (err) {
+		put_device(&root->dev);
+		return ERR_PTR(err);
+	}
+
+	if (owner) {
+		struct module_kobject *mk = &owner->mkobj;
+
+		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
+		if (err) {
+			device_unregister(&root->dev);
+			return ERR_PTR(err);
+		}
+		root->owner = owner;
+	}
+
+	return &root->dev;
+}
+EXPORT_SYMBOL_GPL(__root_device_register);
+
+/**
+ * root_device_unregister - unregister and free a root device
+ * @root: device going away.
+ *
+ * This function unregisters and cleans up a device that was created by
+ * root_device_register().
+ */
+void root_device_unregister(struct device *dev)
+{
+	struct root_device *root = to_root_device(dev);
+
+	if (root->owner)
+		sysfs_remove_link(&root->dev.kobj, "module");
+
+	device_unregister(dev);
+}
+EXPORT_SYMBOL_GPL(root_device_unregister);
+
 
 static void device_create_release(struct device *dev)
 {
diff --git a/include/linux/device.h b/include/linux/device.h
index 1a3686d..9e02980 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -483,6 +483,17 @@ extern int device_rename(struct device *dev, char *new_name);
 extern int device_move(struct device *dev, struct device *new_parent);
 
 /*
+ * Root device objects for grouping under /sys/devices
+ */
+extern struct device *__root_device_register(const char *name,
+					     struct module *owner);
+static inline struct device *root_device_register(const char *name)
+{
+	return __root_device_register(name, THIS_MODULE);
+}
+extern void root_device_unregister(struct device *root);
+
+/*
  * Manual binding of a device to driver. See drivers/base/bus.c
  * for information on use.
  */
-- 
1.6.0.3

Re: [PATCH 1/4] driver core: add root_device_register()

[Cornelia Huck]

On Fri, 12 Dec 2008 08:56:49 +0000,
Mark McLoughlin <markmc@redhat.com> wrote:

> Yeah, I just figured it was a little overkill given the structure
> definition is three lines away. Here it is, though.

As you use it twice, I think it makes the code more readable.

> 
> Cheers,
> Mark.
> 
> From: Mark McLoughlin <markmc@redhat.com>
> Subject: [PATCH] driver core: add root_device_register()
> 
> Add support for allocating root device objects which group
> device objects under /sys/devices directories.
> 
> Also add a sysfs 'module' symlink which points to the owner
> of the root device object. This symlink will be used in virtio
> to allow userspace to determine which virtio bus implementation
> a given device is associated with.
> 
> [Includes suggestions from Cornelia Huck]
> 
> Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>

> ---
>  drivers/base/core.c    |   89 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/device.h |   11 ++++++
>  2 files changed, 100 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 8c2cc26..05320af 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1196,6 +1196,95 @@ EXPORT_SYMBOL_GPL(put_device);
>  EXPORT_SYMBOL_GPL(device_create_file);
>  EXPORT_SYMBOL_GPL(device_remove_file);
> 
> +struct root_device
> +{
> +	struct device dev;
> +	struct module *owner;
> +};
> +
> +#define to_root_device(dev) container_of(dev, struct root_device, dev)
> +
> +static void root_device_release(struct device *dev)
> +{
> +	kfree(to_root_device(dev));
> +}
> +
> +/**
> + * __root_device_register - allocate and register a root device
> + * @name: root device name
> + * @owner: owner module of the root device, usually THIS_MODULE
> + *
> + * This function allocates a root device and registers it
> + * using device_register(). In order to free the returned
> + * device, use root_device_unregister().
> + *
> + * Root devices are dummy devices which allow other devices
> + * to be grouped under /sys/devices. Use this function to
> + * allocate a root device and then use it as the parent of
> + * any device which should appear under /sys/devices/{name}
> + *
> + * The /sys/devices/{name} directory will also contain a
> + * 'module' symlink which points to the @owner directory
> + * in sysfs.
> + *
> + * Note: You probably want to use root_device_register().
> + */
> +struct device *__root_device_register(const char *name, struct module *owner)
> +{
> +	struct root_device *root;
> +	int err = -ENOMEM;
> +
> +	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
> +	if (!root)
> +		return ERR_PTR(err);
> +
> +	err = dev_set_name(&root->dev, name);
> +	if (err) {
> +		kfree(root);
> +		return ERR_PTR(err);
> +	}
> +
> +	root->dev.release = root_device_release;
> +
> +	err = device_register(&root->dev);
> +	if (err) {
> +		put_device(&root->dev);
> +		return ERR_PTR(err);
> +	}
> +
> +	if (owner) {
> +		struct module_kobject *mk = &owner->mkobj;
> +
> +		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
> +		if (err) {
> +			device_unregister(&root->dev);
> +			return ERR_PTR(err);
> +		}
> +		root->owner = owner;
> +	}
> +
> +	return &root->dev;
> +}
> +EXPORT_SYMBOL_GPL(__root_device_register);
> +
> +/**
> + * root_device_unregister - unregister and free a root device
> + * @root: device going away.
> + *
> + * This function unregisters and cleans up a device that was created by
> + * root_device_register().
> + */
> +void root_device_unregister(struct device *dev)
> +{
> +	struct root_device *root = to_root_device(dev);
> +
> +	if (root->owner)
> +		sysfs_remove_link(&root->dev.kobj, "module");
> +
> +	device_unregister(dev);
> +}
> +EXPORT_SYMBOL_GPL(root_device_unregister);
> +
> 
>  static void device_create_release(struct device *dev)
>  {
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 1a3686d..9e02980 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -483,6 +483,17 @@ extern int device_rename(struct device *dev, char *new_name);
>  extern int device_move(struct device *dev, struct device *new_parent);
> 
>  /*
> + * Root device objects for grouping under /sys/devices
> + */
> +extern struct device *__root_device_register(const char *name,
> +					     struct module *owner);
> +static inline struct device *root_device_register(const char *name)
> +{
> +	return __root_device_register(name, THIS_MODULE);
> +}
> +extern void root_device_unregister(struct device *root);
> +
> +/*
>   * Manual binding of a device to driver. See drivers/base/bus.c
>   * for information on use.
>   */
> -- 
> 1.6.0.3
>