cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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bus.c (30449B)


      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * bus.c - bus driver management
      4 *
      5 * Copyright (c) 2002-3 Patrick Mochel
      6 * Copyright (c) 2002-3 Open Source Development Labs
      7 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
      8 * Copyright (c) 2007 Novell Inc.
      9 */
     10
     11#include <linux/async.h>
     12#include <linux/device/bus.h>
     13#include <linux/device.h>
     14#include <linux/module.h>
     15#include <linux/errno.h>
     16#include <linux/slab.h>
     17#include <linux/init.h>
     18#include <linux/string.h>
     19#include <linux/mutex.h>
     20#include <linux/sysfs.h>
     21#include "base.h"
     22#include "power/power.h"
     23
     24/* /sys/devices/system */
     25static struct kset *system_kset;
     26
     27#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
     28
     29/*
     30 * sysfs bindings for drivers
     31 */
     32
     33#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
     34
     35#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \
     36	struct driver_attribute driver_attr_##_name =		\
     37		__ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)
     38
     39static int __must_check bus_rescan_devices_helper(struct device *dev,
     40						void *data);
     41
     42static struct bus_type *bus_get(struct bus_type *bus)
     43{
     44	if (bus) {
     45		kset_get(&bus->p->subsys);
     46		return bus;
     47	}
     48	return NULL;
     49}
     50
     51static void bus_put(struct bus_type *bus)
     52{
     53	if (bus)
     54		kset_put(&bus->p->subsys);
     55}
     56
     57static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
     58			     char *buf)
     59{
     60	struct driver_attribute *drv_attr = to_drv_attr(attr);
     61	struct driver_private *drv_priv = to_driver(kobj);
     62	ssize_t ret = -EIO;
     63
     64	if (drv_attr->show)
     65		ret = drv_attr->show(drv_priv->driver, buf);
     66	return ret;
     67}
     68
     69static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
     70			      const char *buf, size_t count)
     71{
     72	struct driver_attribute *drv_attr = to_drv_attr(attr);
     73	struct driver_private *drv_priv = to_driver(kobj);
     74	ssize_t ret = -EIO;
     75
     76	if (drv_attr->store)
     77		ret = drv_attr->store(drv_priv->driver, buf, count);
     78	return ret;
     79}
     80
     81static const struct sysfs_ops driver_sysfs_ops = {
     82	.show	= drv_attr_show,
     83	.store	= drv_attr_store,
     84};
     85
     86static void driver_release(struct kobject *kobj)
     87{
     88	struct driver_private *drv_priv = to_driver(kobj);
     89
     90	pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
     91	kfree(drv_priv);
     92}
     93
     94static struct kobj_type driver_ktype = {
     95	.sysfs_ops	= &driver_sysfs_ops,
     96	.release	= driver_release,
     97};
     98
     99/*
    100 * sysfs bindings for buses
    101 */
    102static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
    103			     char *buf)
    104{
    105	struct bus_attribute *bus_attr = to_bus_attr(attr);
    106	struct subsys_private *subsys_priv = to_subsys_private(kobj);
    107	ssize_t ret = 0;
    108
    109	if (bus_attr->show)
    110		ret = bus_attr->show(subsys_priv->bus, buf);
    111	return ret;
    112}
    113
    114static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
    115			      const char *buf, size_t count)
    116{
    117	struct bus_attribute *bus_attr = to_bus_attr(attr);
    118	struct subsys_private *subsys_priv = to_subsys_private(kobj);
    119	ssize_t ret = 0;
    120
    121	if (bus_attr->store)
    122		ret = bus_attr->store(subsys_priv->bus, buf, count);
    123	return ret;
    124}
    125
    126static const struct sysfs_ops bus_sysfs_ops = {
    127	.show	= bus_attr_show,
    128	.store	= bus_attr_store,
    129};
    130
    131int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
    132{
    133	int error;
    134	if (bus_get(bus)) {
    135		error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
    136		bus_put(bus);
    137	} else
    138		error = -EINVAL;
    139	return error;
    140}
    141EXPORT_SYMBOL_GPL(bus_create_file);
    142
    143void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
    144{
    145	if (bus_get(bus)) {
    146		sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
    147		bus_put(bus);
    148	}
    149}
    150EXPORT_SYMBOL_GPL(bus_remove_file);
    151
    152static void bus_release(struct kobject *kobj)
    153{
    154	struct subsys_private *priv = to_subsys_private(kobj);
    155	struct bus_type *bus = priv->bus;
    156
    157	kfree(priv);
    158	bus->p = NULL;
    159}
    160
    161static struct kobj_type bus_ktype = {
    162	.sysfs_ops	= &bus_sysfs_ops,
    163	.release	= bus_release,
    164};
    165
    166static int bus_uevent_filter(struct kobject *kobj)
    167{
    168	const struct kobj_type *ktype = get_ktype(kobj);
    169
    170	if (ktype == &bus_ktype)
    171		return 1;
    172	return 0;
    173}
    174
    175static const struct kset_uevent_ops bus_uevent_ops = {
    176	.filter = bus_uevent_filter,
    177};
    178
    179static struct kset *bus_kset;
    180
    181/* Manually detach a device from its associated driver. */
    182static ssize_t unbind_store(struct device_driver *drv, const char *buf,
    183			    size_t count)
    184{
    185	struct bus_type *bus = bus_get(drv->bus);
    186	struct device *dev;
    187	int err = -ENODEV;
    188
    189	dev = bus_find_device_by_name(bus, NULL, buf);
    190	if (dev && dev->driver == drv) {
    191		device_driver_detach(dev);
    192		err = count;
    193	}
    194	put_device(dev);
    195	bus_put(bus);
    196	return err;
    197}
    198static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);
    199
    200/*
    201 * Manually attach a device to a driver.
    202 * Note: the driver must want to bind to the device,
    203 * it is not possible to override the driver's id table.
    204 */
    205static ssize_t bind_store(struct device_driver *drv, const char *buf,
    206			  size_t count)
    207{
    208	struct bus_type *bus = bus_get(drv->bus);
    209	struct device *dev;
    210	int err = -ENODEV;
    211
    212	dev = bus_find_device_by_name(bus, NULL, buf);
    213	if (dev && driver_match_device(drv, dev)) {
    214		err = device_driver_attach(drv, dev);
    215		if (!err) {
    216			/* success */
    217			err = count;
    218		}
    219	}
    220	put_device(dev);
    221	bus_put(bus);
    222	return err;
    223}
    224static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);
    225
    226static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
    227{
    228	return sysfs_emit(buf, "%d\n", bus->p->drivers_autoprobe);
    229}
    230
    231static ssize_t drivers_autoprobe_store(struct bus_type *bus,
    232				       const char *buf, size_t count)
    233{
    234	if (buf[0] == '0')
    235		bus->p->drivers_autoprobe = 0;
    236	else
    237		bus->p->drivers_autoprobe = 1;
    238	return count;
    239}
    240
    241static ssize_t drivers_probe_store(struct bus_type *bus,
    242				   const char *buf, size_t count)
    243{
    244	struct device *dev;
    245	int err = -EINVAL;
    246
    247	dev = bus_find_device_by_name(bus, NULL, buf);
    248	if (!dev)
    249		return -ENODEV;
    250	if (bus_rescan_devices_helper(dev, NULL) == 0)
    251		err = count;
    252	put_device(dev);
    253	return err;
    254}
    255
    256static struct device *next_device(struct klist_iter *i)
    257{
    258	struct klist_node *n = klist_next(i);
    259	struct device *dev = NULL;
    260	struct device_private *dev_prv;
    261
    262	if (n) {
    263		dev_prv = to_device_private_bus(n);
    264		dev = dev_prv->device;
    265	}
    266	return dev;
    267}
    268
    269/**
    270 * bus_for_each_dev - device iterator.
    271 * @bus: bus type.
    272 * @start: device to start iterating from.
    273 * @data: data for the callback.
    274 * @fn: function to be called for each device.
    275 *
    276 * Iterate over @bus's list of devices, and call @fn for each,
    277 * passing it @data. If @start is not NULL, we use that device to
    278 * begin iterating from.
    279 *
    280 * We check the return of @fn each time. If it returns anything
    281 * other than 0, we break out and return that value.
    282 *
    283 * NOTE: The device that returns a non-zero value is not retained
    284 * in any way, nor is its refcount incremented. If the caller needs
    285 * to retain this data, it should do so, and increment the reference
    286 * count in the supplied callback.
    287 */
    288int bus_for_each_dev(struct bus_type *bus, struct device *start,
    289		     void *data, int (*fn)(struct device *, void *))
    290{
    291	struct klist_iter i;
    292	struct device *dev;
    293	int error = 0;
    294
    295	if (!bus || !bus->p)
    296		return -EINVAL;
    297
    298	klist_iter_init_node(&bus->p->klist_devices, &i,
    299			     (start ? &start->p->knode_bus : NULL));
    300	while (!error && (dev = next_device(&i)))
    301		error = fn(dev, data);
    302	klist_iter_exit(&i);
    303	return error;
    304}
    305EXPORT_SYMBOL_GPL(bus_for_each_dev);
    306
    307/**
    308 * bus_find_device - device iterator for locating a particular device.
    309 * @bus: bus type
    310 * @start: Device to begin with
    311 * @data: Data to pass to match function
    312 * @match: Callback function to check device
    313 *
    314 * This is similar to the bus_for_each_dev() function above, but it
    315 * returns a reference to a device that is 'found' for later use, as
    316 * determined by the @match callback.
    317 *
    318 * The callback should return 0 if the device doesn't match and non-zero
    319 * if it does.  If the callback returns non-zero, this function will
    320 * return to the caller and not iterate over any more devices.
    321 */
    322struct device *bus_find_device(struct bus_type *bus,
    323			       struct device *start, const void *data,
    324			       int (*match)(struct device *dev, const void *data))
    325{
    326	struct klist_iter i;
    327	struct device *dev;
    328
    329	if (!bus || !bus->p)
    330		return NULL;
    331
    332	klist_iter_init_node(&bus->p->klist_devices, &i,
    333			     (start ? &start->p->knode_bus : NULL));
    334	while ((dev = next_device(&i)))
    335		if (match(dev, data) && get_device(dev))
    336			break;
    337	klist_iter_exit(&i);
    338	return dev;
    339}
    340EXPORT_SYMBOL_GPL(bus_find_device);
    341
    342/**
    343 * subsys_find_device_by_id - find a device with a specific enumeration number
    344 * @subsys: subsystem
    345 * @id: index 'id' in struct device
    346 * @hint: device to check first
    347 *
    348 * Check the hint's next object and if it is a match return it directly,
    349 * otherwise, fall back to a full list search. Either way a reference for
    350 * the returned object is taken.
    351 */
    352struct device *subsys_find_device_by_id(struct bus_type *subsys, unsigned int id,
    353					struct device *hint)
    354{
    355	struct klist_iter i;
    356	struct device *dev;
    357
    358	if (!subsys)
    359		return NULL;
    360
    361	if (hint) {
    362		klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
    363		dev = next_device(&i);
    364		if (dev && dev->id == id && get_device(dev)) {
    365			klist_iter_exit(&i);
    366			return dev;
    367		}
    368		klist_iter_exit(&i);
    369	}
    370
    371	klist_iter_init_node(&subsys->p->klist_devices, &i, NULL);
    372	while ((dev = next_device(&i))) {
    373		if (dev->id == id && get_device(dev)) {
    374			klist_iter_exit(&i);
    375			return dev;
    376		}
    377	}
    378	klist_iter_exit(&i);
    379	return NULL;
    380}
    381EXPORT_SYMBOL_GPL(subsys_find_device_by_id);
    382
    383static struct device_driver *next_driver(struct klist_iter *i)
    384{
    385	struct klist_node *n = klist_next(i);
    386	struct driver_private *drv_priv;
    387
    388	if (n) {
    389		drv_priv = container_of(n, struct driver_private, knode_bus);
    390		return drv_priv->driver;
    391	}
    392	return NULL;
    393}
    394
    395/**
    396 * bus_for_each_drv - driver iterator
    397 * @bus: bus we're dealing with.
    398 * @start: driver to start iterating on.
    399 * @data: data to pass to the callback.
    400 * @fn: function to call for each driver.
    401 *
    402 * This is nearly identical to the device iterator above.
    403 * We iterate over each driver that belongs to @bus, and call
    404 * @fn for each. If @fn returns anything but 0, we break out
    405 * and return it. If @start is not NULL, we use it as the head
    406 * of the list.
    407 *
    408 * NOTE: we don't return the driver that returns a non-zero
    409 * value, nor do we leave the reference count incremented for that
    410 * driver. If the caller needs to know that info, it must set it
    411 * in the callback. It must also be sure to increment the refcount
    412 * so it doesn't disappear before returning to the caller.
    413 */
    414int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
    415		     void *data, int (*fn)(struct device_driver *, void *))
    416{
    417	struct klist_iter i;
    418	struct device_driver *drv;
    419	int error = 0;
    420
    421	if (!bus)
    422		return -EINVAL;
    423
    424	klist_iter_init_node(&bus->p->klist_drivers, &i,
    425			     start ? &start->p->knode_bus : NULL);
    426	while ((drv = next_driver(&i)) && !error)
    427		error = fn(drv, data);
    428	klist_iter_exit(&i);
    429	return error;
    430}
    431EXPORT_SYMBOL_GPL(bus_for_each_drv);
    432
    433/**
    434 * bus_add_device - add device to bus
    435 * @dev: device being added
    436 *
    437 * - Add device's bus attributes.
    438 * - Create links to device's bus.
    439 * - Add the device to its bus's list of devices.
    440 */
    441int bus_add_device(struct device *dev)
    442{
    443	struct bus_type *bus = bus_get(dev->bus);
    444	int error = 0;
    445
    446	if (bus) {
    447		pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
    448		error = device_add_groups(dev, bus->dev_groups);
    449		if (error)
    450			goto out_put;
    451		error = sysfs_create_link(&bus->p->devices_kset->kobj,
    452						&dev->kobj, dev_name(dev));
    453		if (error)
    454			goto out_groups;
    455		error = sysfs_create_link(&dev->kobj,
    456				&dev->bus->p->subsys.kobj, "subsystem");
    457		if (error)
    458			goto out_subsys;
    459		klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
    460	}
    461	return 0;
    462
    463out_subsys:
    464	sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
    465out_groups:
    466	device_remove_groups(dev, bus->dev_groups);
    467out_put:
    468	bus_put(dev->bus);
    469	return error;
    470}
    471
    472/**
    473 * bus_probe_device - probe drivers for a new device
    474 * @dev: device to probe
    475 *
    476 * - Automatically probe for a driver if the bus allows it.
    477 */
    478void bus_probe_device(struct device *dev)
    479{
    480	struct bus_type *bus = dev->bus;
    481	struct subsys_interface *sif;
    482
    483	if (!bus)
    484		return;
    485
    486	if (bus->p->drivers_autoprobe)
    487		device_initial_probe(dev);
    488
    489	mutex_lock(&bus->p->mutex);
    490	list_for_each_entry(sif, &bus->p->interfaces, node)
    491		if (sif->add_dev)
    492			sif->add_dev(dev, sif);
    493	mutex_unlock(&bus->p->mutex);
    494}
    495
    496/**
    497 * bus_remove_device - remove device from bus
    498 * @dev: device to be removed
    499 *
    500 * - Remove device from all interfaces.
    501 * - Remove symlink from bus' directory.
    502 * - Delete device from bus's list.
    503 * - Detach from its driver.
    504 * - Drop reference taken in bus_add_device().
    505 */
    506void bus_remove_device(struct device *dev)
    507{
    508	struct bus_type *bus = dev->bus;
    509	struct subsys_interface *sif;
    510
    511	if (!bus)
    512		return;
    513
    514	mutex_lock(&bus->p->mutex);
    515	list_for_each_entry(sif, &bus->p->interfaces, node)
    516		if (sif->remove_dev)
    517			sif->remove_dev(dev, sif);
    518	mutex_unlock(&bus->p->mutex);
    519
    520	sysfs_remove_link(&dev->kobj, "subsystem");
    521	sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
    522			  dev_name(dev));
    523	device_remove_groups(dev, dev->bus->dev_groups);
    524	if (klist_node_attached(&dev->p->knode_bus))
    525		klist_del(&dev->p->knode_bus);
    526
    527	pr_debug("bus: '%s': remove device %s\n",
    528		 dev->bus->name, dev_name(dev));
    529	device_release_driver(dev);
    530	bus_put(dev->bus);
    531}
    532
    533static int __must_check add_bind_files(struct device_driver *drv)
    534{
    535	int ret;
    536
    537	ret = driver_create_file(drv, &driver_attr_unbind);
    538	if (ret == 0) {
    539		ret = driver_create_file(drv, &driver_attr_bind);
    540		if (ret)
    541			driver_remove_file(drv, &driver_attr_unbind);
    542	}
    543	return ret;
    544}
    545
    546static void remove_bind_files(struct device_driver *drv)
    547{
    548	driver_remove_file(drv, &driver_attr_bind);
    549	driver_remove_file(drv, &driver_attr_unbind);
    550}
    551
    552static BUS_ATTR_WO(drivers_probe);
    553static BUS_ATTR_RW(drivers_autoprobe);
    554
    555static int add_probe_files(struct bus_type *bus)
    556{
    557	int retval;
    558
    559	retval = bus_create_file(bus, &bus_attr_drivers_probe);
    560	if (retval)
    561		goto out;
    562
    563	retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
    564	if (retval)
    565		bus_remove_file(bus, &bus_attr_drivers_probe);
    566out:
    567	return retval;
    568}
    569
    570static void remove_probe_files(struct bus_type *bus)
    571{
    572	bus_remove_file(bus, &bus_attr_drivers_autoprobe);
    573	bus_remove_file(bus, &bus_attr_drivers_probe);
    574}
    575
    576static ssize_t uevent_store(struct device_driver *drv, const char *buf,
    577			    size_t count)
    578{
    579	int rc;
    580
    581	rc = kobject_synth_uevent(&drv->p->kobj, buf, count);
    582	return rc ? rc : count;
    583}
    584static DRIVER_ATTR_WO(uevent);
    585
    586/**
    587 * bus_add_driver - Add a driver to the bus.
    588 * @drv: driver.
    589 */
    590int bus_add_driver(struct device_driver *drv)
    591{
    592	struct bus_type *bus;
    593	struct driver_private *priv;
    594	int error = 0;
    595
    596	bus = bus_get(drv->bus);
    597	if (!bus)
    598		return -EINVAL;
    599
    600	pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
    601
    602	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    603	if (!priv) {
    604		error = -ENOMEM;
    605		goto out_put_bus;
    606	}
    607	klist_init(&priv->klist_devices, NULL, NULL);
    608	priv->driver = drv;
    609	drv->p = priv;
    610	priv->kobj.kset = bus->p->drivers_kset;
    611	error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
    612				     "%s", drv->name);
    613	if (error)
    614		goto out_unregister;
    615
    616	klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
    617	if (drv->bus->p->drivers_autoprobe) {
    618		error = driver_attach(drv);
    619		if (error)
    620			goto out_del_list;
    621	}
    622	module_add_driver(drv->owner, drv);
    623
    624	error = driver_create_file(drv, &driver_attr_uevent);
    625	if (error) {
    626		printk(KERN_ERR "%s: uevent attr (%s) failed\n",
    627			__func__, drv->name);
    628	}
    629	error = driver_add_groups(drv, bus->drv_groups);
    630	if (error) {
    631		/* How the hell do we get out of this pickle? Give up */
    632		printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
    633			__func__, drv->name);
    634	}
    635
    636	if (!drv->suppress_bind_attrs) {
    637		error = add_bind_files(drv);
    638		if (error) {
    639			/* Ditto */
    640			printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
    641				__func__, drv->name);
    642		}
    643	}
    644
    645	return 0;
    646
    647out_del_list:
    648	klist_del(&priv->knode_bus);
    649out_unregister:
    650	kobject_put(&priv->kobj);
    651	/* drv->p is freed in driver_release()  */
    652	drv->p = NULL;
    653out_put_bus:
    654	bus_put(bus);
    655	return error;
    656}
    657
    658/**
    659 * bus_remove_driver - delete driver from bus's knowledge.
    660 * @drv: driver.
    661 *
    662 * Detach the driver from the devices it controls, and remove
    663 * it from its bus's list of drivers. Finally, we drop the reference
    664 * to the bus we took in bus_add_driver().
    665 */
    666void bus_remove_driver(struct device_driver *drv)
    667{
    668	if (!drv->bus)
    669		return;
    670
    671	if (!drv->suppress_bind_attrs)
    672		remove_bind_files(drv);
    673	driver_remove_groups(drv, drv->bus->drv_groups);
    674	driver_remove_file(drv, &driver_attr_uevent);
    675	klist_remove(&drv->p->knode_bus);
    676	pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
    677	driver_detach(drv);
    678	module_remove_driver(drv);
    679	kobject_put(&drv->p->kobj);
    680	bus_put(drv->bus);
    681}
    682
    683/* Helper for bus_rescan_devices's iter */
    684static int __must_check bus_rescan_devices_helper(struct device *dev,
    685						  void *data)
    686{
    687	int ret = 0;
    688
    689	if (!dev->driver) {
    690		if (dev->parent && dev->bus->need_parent_lock)
    691			device_lock(dev->parent);
    692		ret = device_attach(dev);
    693		if (dev->parent && dev->bus->need_parent_lock)
    694			device_unlock(dev->parent);
    695	}
    696	return ret < 0 ? ret : 0;
    697}
    698
    699/**
    700 * bus_rescan_devices - rescan devices on the bus for possible drivers
    701 * @bus: the bus to scan.
    702 *
    703 * This function will look for devices on the bus with no driver
    704 * attached and rescan it against existing drivers to see if it matches
    705 * any by calling device_attach() for the unbound devices.
    706 */
    707int bus_rescan_devices(struct bus_type *bus)
    708{
    709	return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
    710}
    711EXPORT_SYMBOL_GPL(bus_rescan_devices);
    712
    713/**
    714 * device_reprobe - remove driver for a device and probe for a new driver
    715 * @dev: the device to reprobe
    716 *
    717 * This function detaches the attached driver (if any) for the given
    718 * device and restarts the driver probing process.  It is intended
    719 * to use if probing criteria changed during a devices lifetime and
    720 * driver attachment should change accordingly.
    721 */
    722int device_reprobe(struct device *dev)
    723{
    724	if (dev->driver)
    725		device_driver_detach(dev);
    726	return bus_rescan_devices_helper(dev, NULL);
    727}
    728EXPORT_SYMBOL_GPL(device_reprobe);
    729
    730static int bus_add_groups(struct bus_type *bus,
    731			  const struct attribute_group **groups)
    732{
    733	return sysfs_create_groups(&bus->p->subsys.kobj, groups);
    734}
    735
    736static void bus_remove_groups(struct bus_type *bus,
    737			      const struct attribute_group **groups)
    738{
    739	sysfs_remove_groups(&bus->p->subsys.kobj, groups);
    740}
    741
    742static void klist_devices_get(struct klist_node *n)
    743{
    744	struct device_private *dev_prv = to_device_private_bus(n);
    745	struct device *dev = dev_prv->device;
    746
    747	get_device(dev);
    748}
    749
    750static void klist_devices_put(struct klist_node *n)
    751{
    752	struct device_private *dev_prv = to_device_private_bus(n);
    753	struct device *dev = dev_prv->device;
    754
    755	put_device(dev);
    756}
    757
    758static ssize_t bus_uevent_store(struct bus_type *bus,
    759				const char *buf, size_t count)
    760{
    761	int rc;
    762
    763	rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
    764	return rc ? rc : count;
    765}
    766/*
    767 * "open code" the old BUS_ATTR() macro here.  We want to use BUS_ATTR_WO()
    768 * here, but can not use it as earlier in the file we have
    769 * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
    770 * function name.
    771 */
    772static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
    773						     bus_uevent_store);
    774
    775/**
    776 * bus_register - register a driver-core subsystem
    777 * @bus: bus to register
    778 *
    779 * Once we have that, we register the bus with the kobject
    780 * infrastructure, then register the children subsystems it has:
    781 * the devices and drivers that belong to the subsystem.
    782 */
    783int bus_register(struct bus_type *bus)
    784{
    785	int retval;
    786	struct subsys_private *priv;
    787	struct lock_class_key *key = &bus->lock_key;
    788
    789	priv = kzalloc(sizeof(struct subsys_private), GFP_KERNEL);
    790	if (!priv)
    791		return -ENOMEM;
    792
    793	priv->bus = bus;
    794	bus->p = priv;
    795
    796	BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
    797
    798	retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
    799	if (retval)
    800		goto out;
    801
    802	priv->subsys.kobj.kset = bus_kset;
    803	priv->subsys.kobj.ktype = &bus_ktype;
    804	priv->drivers_autoprobe = 1;
    805
    806	retval = kset_register(&priv->subsys);
    807	if (retval)
    808		goto out;
    809
    810	retval = bus_create_file(bus, &bus_attr_uevent);
    811	if (retval)
    812		goto bus_uevent_fail;
    813
    814	priv->devices_kset = kset_create_and_add("devices", NULL,
    815						 &priv->subsys.kobj);
    816	if (!priv->devices_kset) {
    817		retval = -ENOMEM;
    818		goto bus_devices_fail;
    819	}
    820
    821	priv->drivers_kset = kset_create_and_add("drivers", NULL,
    822						 &priv->subsys.kobj);
    823	if (!priv->drivers_kset) {
    824		retval = -ENOMEM;
    825		goto bus_drivers_fail;
    826	}
    827
    828	INIT_LIST_HEAD(&priv->interfaces);
    829	__mutex_init(&priv->mutex, "subsys mutex", key);
    830	klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
    831	klist_init(&priv->klist_drivers, NULL, NULL);
    832
    833	retval = add_probe_files(bus);
    834	if (retval)
    835		goto bus_probe_files_fail;
    836
    837	retval = bus_add_groups(bus, bus->bus_groups);
    838	if (retval)
    839		goto bus_groups_fail;
    840
    841	pr_debug("bus: '%s': registered\n", bus->name);
    842	return 0;
    843
    844bus_groups_fail:
    845	remove_probe_files(bus);
    846bus_probe_files_fail:
    847	kset_unregister(bus->p->drivers_kset);
    848bus_drivers_fail:
    849	kset_unregister(bus->p->devices_kset);
    850bus_devices_fail:
    851	bus_remove_file(bus, &bus_attr_uevent);
    852bus_uevent_fail:
    853	kset_unregister(&bus->p->subsys);
    854out:
    855	kfree(bus->p);
    856	bus->p = NULL;
    857	return retval;
    858}
    859EXPORT_SYMBOL_GPL(bus_register);
    860
    861/**
    862 * bus_unregister - remove a bus from the system
    863 * @bus: bus.
    864 *
    865 * Unregister the child subsystems and the bus itself.
    866 * Finally, we call bus_put() to release the refcount
    867 */
    868void bus_unregister(struct bus_type *bus)
    869{
    870	pr_debug("bus: '%s': unregistering\n", bus->name);
    871	if (bus->dev_root)
    872		device_unregister(bus->dev_root);
    873	bus_remove_groups(bus, bus->bus_groups);
    874	remove_probe_files(bus);
    875	kset_unregister(bus->p->drivers_kset);
    876	kset_unregister(bus->p->devices_kset);
    877	bus_remove_file(bus, &bus_attr_uevent);
    878	kset_unregister(&bus->p->subsys);
    879}
    880EXPORT_SYMBOL_GPL(bus_unregister);
    881
    882int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
    883{
    884	return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
    885}
    886EXPORT_SYMBOL_GPL(bus_register_notifier);
    887
    888int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
    889{
    890	return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
    891}
    892EXPORT_SYMBOL_GPL(bus_unregister_notifier);
    893
    894struct kset *bus_get_kset(struct bus_type *bus)
    895{
    896	return &bus->p->subsys;
    897}
    898EXPORT_SYMBOL_GPL(bus_get_kset);
    899
    900struct klist *bus_get_device_klist(struct bus_type *bus)
    901{
    902	return &bus->p->klist_devices;
    903}
    904EXPORT_SYMBOL_GPL(bus_get_device_klist);
    905
    906/*
    907 * Yes, this forcibly breaks the klist abstraction temporarily.  It
    908 * just wants to sort the klist, not change reference counts and
    909 * take/drop locks rapidly in the process.  It does all this while
    910 * holding the lock for the list, so objects can't otherwise be
    911 * added/removed while we're swizzling.
    912 */
    913static void device_insertion_sort_klist(struct device *a, struct list_head *list,
    914					int (*compare)(const struct device *a,
    915							const struct device *b))
    916{
    917	struct klist_node *n;
    918	struct device_private *dev_prv;
    919	struct device *b;
    920
    921	list_for_each_entry(n, list, n_node) {
    922		dev_prv = to_device_private_bus(n);
    923		b = dev_prv->device;
    924		if (compare(a, b) <= 0) {
    925			list_move_tail(&a->p->knode_bus.n_node,
    926				       &b->p->knode_bus.n_node);
    927			return;
    928		}
    929	}
    930	list_move_tail(&a->p->knode_bus.n_node, list);
    931}
    932
    933void bus_sort_breadthfirst(struct bus_type *bus,
    934			   int (*compare)(const struct device *a,
    935					  const struct device *b))
    936{
    937	LIST_HEAD(sorted_devices);
    938	struct klist_node *n, *tmp;
    939	struct device_private *dev_prv;
    940	struct device *dev;
    941	struct klist *device_klist;
    942
    943	device_klist = bus_get_device_klist(bus);
    944
    945	spin_lock(&device_klist->k_lock);
    946	list_for_each_entry_safe(n, tmp, &device_klist->k_list, n_node) {
    947		dev_prv = to_device_private_bus(n);
    948		dev = dev_prv->device;
    949		device_insertion_sort_klist(dev, &sorted_devices, compare);
    950	}
    951	list_splice(&sorted_devices, &device_klist->k_list);
    952	spin_unlock(&device_klist->k_lock);
    953}
    954EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
    955
    956/**
    957 * subsys_dev_iter_init - initialize subsys device iterator
    958 * @iter: subsys iterator to initialize
    959 * @subsys: the subsys we wanna iterate over
    960 * @start: the device to start iterating from, if any
    961 * @type: device_type of the devices to iterate over, NULL for all
    962 *
    963 * Initialize subsys iterator @iter such that it iterates over devices
    964 * of @subsys.  If @start is set, the list iteration will start there,
    965 * otherwise if it is NULL, the iteration starts at the beginning of
    966 * the list.
    967 */
    968void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
    969			  struct device *start, const struct device_type *type)
    970{
    971	struct klist_node *start_knode = NULL;
    972
    973	if (start)
    974		start_knode = &start->p->knode_bus;
    975	klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
    976	iter->type = type;
    977}
    978EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
    979
    980/**
    981 * subsys_dev_iter_next - iterate to the next device
    982 * @iter: subsys iterator to proceed
    983 *
    984 * Proceed @iter to the next device and return it.  Returns NULL if
    985 * iteration is complete.
    986 *
    987 * The returned device is referenced and won't be released till
    988 * iterator is proceed to the next device or exited.  The caller is
    989 * free to do whatever it wants to do with the device including
    990 * calling back into subsys code.
    991 */
    992struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter)
    993{
    994	struct klist_node *knode;
    995	struct device *dev;
    996
    997	for (;;) {
    998		knode = klist_next(&iter->ki);
    999		if (!knode)
   1000			return NULL;
   1001		dev = to_device_private_bus(knode)->device;
   1002		if (!iter->type || iter->type == dev->type)
   1003			return dev;
   1004	}
   1005}
   1006EXPORT_SYMBOL_GPL(subsys_dev_iter_next);
   1007
   1008/**
   1009 * subsys_dev_iter_exit - finish iteration
   1010 * @iter: subsys iterator to finish
   1011 *
   1012 * Finish an iteration.  Always call this function after iteration is
   1013 * complete whether the iteration ran till the end or not.
   1014 */
   1015void subsys_dev_iter_exit(struct subsys_dev_iter *iter)
   1016{
   1017	klist_iter_exit(&iter->ki);
   1018}
   1019EXPORT_SYMBOL_GPL(subsys_dev_iter_exit);
   1020
   1021int subsys_interface_register(struct subsys_interface *sif)
   1022{
   1023	struct bus_type *subsys;
   1024	struct subsys_dev_iter iter;
   1025	struct device *dev;
   1026
   1027	if (!sif || !sif->subsys)
   1028		return -ENODEV;
   1029
   1030	subsys = bus_get(sif->subsys);
   1031	if (!subsys)
   1032		return -EINVAL;
   1033
   1034	mutex_lock(&subsys->p->mutex);
   1035	list_add_tail(&sif->node, &subsys->p->interfaces);
   1036	if (sif->add_dev) {
   1037		subsys_dev_iter_init(&iter, subsys, NULL, NULL);
   1038		while ((dev = subsys_dev_iter_next(&iter)))
   1039			sif->add_dev(dev, sif);
   1040		subsys_dev_iter_exit(&iter);
   1041	}
   1042	mutex_unlock(&subsys->p->mutex);
   1043
   1044	return 0;
   1045}
   1046EXPORT_SYMBOL_GPL(subsys_interface_register);
   1047
   1048void subsys_interface_unregister(struct subsys_interface *sif)
   1049{
   1050	struct bus_type *subsys;
   1051	struct subsys_dev_iter iter;
   1052	struct device *dev;
   1053
   1054	if (!sif || !sif->subsys)
   1055		return;
   1056
   1057	subsys = sif->subsys;
   1058
   1059	mutex_lock(&subsys->p->mutex);
   1060	list_del_init(&sif->node);
   1061	if (sif->remove_dev) {
   1062		subsys_dev_iter_init(&iter, subsys, NULL, NULL);
   1063		while ((dev = subsys_dev_iter_next(&iter)))
   1064			sif->remove_dev(dev, sif);
   1065		subsys_dev_iter_exit(&iter);
   1066	}
   1067	mutex_unlock(&subsys->p->mutex);
   1068
   1069	bus_put(subsys);
   1070}
   1071EXPORT_SYMBOL_GPL(subsys_interface_unregister);
   1072
   1073static void system_root_device_release(struct device *dev)
   1074{
   1075	kfree(dev);
   1076}
   1077
   1078static int subsys_register(struct bus_type *subsys,
   1079			   const struct attribute_group **groups,
   1080			   struct kobject *parent_of_root)
   1081{
   1082	struct device *dev;
   1083	int err;
   1084
   1085	err = bus_register(subsys);
   1086	if (err < 0)
   1087		return err;
   1088
   1089	dev = kzalloc(sizeof(struct device), GFP_KERNEL);
   1090	if (!dev) {
   1091		err = -ENOMEM;
   1092		goto err_dev;
   1093	}
   1094
   1095	err = dev_set_name(dev, "%s", subsys->name);
   1096	if (err < 0)
   1097		goto err_name;
   1098
   1099	dev->kobj.parent = parent_of_root;
   1100	dev->groups = groups;
   1101	dev->release = system_root_device_release;
   1102
   1103	err = device_register(dev);
   1104	if (err < 0)
   1105		goto err_dev_reg;
   1106
   1107	subsys->dev_root = dev;
   1108	return 0;
   1109
   1110err_dev_reg:
   1111	put_device(dev);
   1112	dev = NULL;
   1113err_name:
   1114	kfree(dev);
   1115err_dev:
   1116	bus_unregister(subsys);
   1117	return err;
   1118}
   1119
   1120/**
   1121 * subsys_system_register - register a subsystem at /sys/devices/system/
   1122 * @subsys: system subsystem
   1123 * @groups: default attributes for the root device
   1124 *
   1125 * All 'system' subsystems have a /sys/devices/system/<name> root device
   1126 * with the name of the subsystem. The root device can carry subsystem-
   1127 * wide attributes. All registered devices are below this single root
   1128 * device and are named after the subsystem with a simple enumeration
   1129 * number appended. The registered devices are not explicitly named;
   1130 * only 'id' in the device needs to be set.
   1131 *
   1132 * Do not use this interface for anything new, it exists for compatibility
   1133 * with bad ideas only. New subsystems should use plain subsystems; and
   1134 * add the subsystem-wide attributes should be added to the subsystem
   1135 * directory itself and not some create fake root-device placed in
   1136 * /sys/devices/system/<name>.
   1137 */
   1138int subsys_system_register(struct bus_type *subsys,
   1139			   const struct attribute_group **groups)
   1140{
   1141	return subsys_register(subsys, groups, &system_kset->kobj);
   1142}
   1143EXPORT_SYMBOL_GPL(subsys_system_register);
   1144
   1145/**
   1146 * subsys_virtual_register - register a subsystem at /sys/devices/virtual/
   1147 * @subsys: virtual subsystem
   1148 * @groups: default attributes for the root device
   1149 *
   1150 * All 'virtual' subsystems have a /sys/devices/system/<name> root device
   1151 * with the name of the subystem.  The root device can carry subsystem-wide
   1152 * attributes.  All registered devices are below this single root device.
   1153 * There's no restriction on device naming.  This is for kernel software
   1154 * constructs which need sysfs interface.
   1155 */
   1156int subsys_virtual_register(struct bus_type *subsys,
   1157			    const struct attribute_group **groups)
   1158{
   1159	struct kobject *virtual_dir;
   1160
   1161	virtual_dir = virtual_device_parent(NULL);
   1162	if (!virtual_dir)
   1163		return -ENOMEM;
   1164
   1165	return subsys_register(subsys, groups, virtual_dir);
   1166}
   1167EXPORT_SYMBOL_GPL(subsys_virtual_register);
   1168
   1169int __init buses_init(void)
   1170{
   1171	bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);
   1172	if (!bus_kset)
   1173		return -ENOMEM;
   1174
   1175	system_kset = kset_create_and_add("system", NULL, &devices_kset->kobj);
   1176	if (!system_kset)
   1177		return -ENOMEM;
   1178
   1179	return 0;
   1180}