2 * bus.c - bus driver management
4 * Copyright (c) 2002-3 Patrick Mochel
5 * Copyright (c) 2002-3 Open Source Development Labs
6 * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
7 * Copyright (c) 2007 Novell Inc.
9 * This file is released under the GPLv2
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>
20 #include "power/power.h"
22 #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
23 #define to_bus(obj) container_of(obj, struct bus_type_private, subsys.kobj)
26 * sysfs bindings for drivers
29 #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
32 static int __must_check bus_rescan_devices_helper(struct device *dev,
35 static struct bus_type *bus_get(struct bus_type *bus)
38 kset_get(&bus->p->subsys);
44 static void bus_put(struct bus_type *bus)
47 kset_put(&bus->p->subsys);
50 static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr,
53 struct driver_attribute *drv_attr = to_drv_attr(attr);
54 struct driver_private *drv_priv = to_driver(kobj);
58 ret = drv_attr->show(drv_priv->driver, buf);
62 static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr,
63 const char *buf, size_t count)
65 struct driver_attribute *drv_attr = to_drv_attr(attr);
66 struct driver_private *drv_priv = to_driver(kobj);
70 ret = drv_attr->store(drv_priv->driver, buf, count);
74 static const struct sysfs_ops driver_sysfs_ops = {
75 .show = drv_attr_show,
76 .store = drv_attr_store,
79 static void driver_release(struct kobject *kobj)
81 struct driver_private *drv_priv = to_driver(kobj);
83 pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__);
87 static struct kobj_type driver_ktype = {
88 .sysfs_ops = &driver_sysfs_ops,
89 .release = driver_release,
93 * sysfs bindings for buses
95 static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
98 struct bus_attribute *bus_attr = to_bus_attr(attr);
99 struct bus_type_private *bus_priv = to_bus(kobj);
103 ret = bus_attr->show(bus_priv->bus, buf);
107 static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
108 const char *buf, size_t count)
110 struct bus_attribute *bus_attr = to_bus_attr(attr);
111 struct bus_type_private *bus_priv = to_bus(kobj);
115 ret = bus_attr->store(bus_priv->bus, buf, count);
119 static const struct sysfs_ops bus_sysfs_ops = {
120 .show = bus_attr_show,
121 .store = bus_attr_store,
124 int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
128 error = sysfs_create_file(&bus->p->subsys.kobj, &attr->attr);
134 EXPORT_SYMBOL_GPL(bus_create_file);
136 void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
139 sysfs_remove_file(&bus->p->subsys.kobj, &attr->attr);
143 EXPORT_SYMBOL_GPL(bus_remove_file);
145 static struct kobj_type bus_ktype = {
146 .sysfs_ops = &bus_sysfs_ops,
149 static int bus_uevent_filter(struct kset *kset, struct kobject *kobj)
151 struct kobj_type *ktype = get_ktype(kobj);
153 if (ktype == &bus_ktype)
158 static const struct kset_uevent_ops bus_uevent_ops = {
159 .filter = bus_uevent_filter,
162 static struct kset *bus_kset;
165 #ifdef CONFIG_HOTPLUG
166 /* Manually detach a device from its associated driver. */
167 static ssize_t driver_unbind(struct device_driver *drv,
168 const char *buf, size_t count)
170 struct bus_type *bus = bus_get(drv->bus);
174 dev = bus_find_device_by_name(bus, NULL, buf);
175 if (dev && dev->driver == drv) {
176 if (dev->parent) /* Needed for USB */
177 device_lock(dev->parent);
178 device_release_driver(dev);
180 device_unlock(dev->parent);
187 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
190 * Manually attach a device to a driver.
191 * Note: the driver must want to bind to the device,
192 * it is not possible to override the driver's id table.
194 static ssize_t driver_bind(struct device_driver *drv,
195 const char *buf, size_t count)
197 struct bus_type *bus = bus_get(drv->bus);
201 dev = bus_find_device_by_name(bus, NULL, buf);
202 if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
203 if (dev->parent) /* Needed for USB */
204 device_lock(dev->parent);
206 err = driver_probe_device(drv, dev);
209 device_unlock(dev->parent);
214 } else if (err == 0) {
215 /* driver didn't accept device */
223 static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
225 static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
227 return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
230 static ssize_t store_drivers_autoprobe(struct bus_type *bus,
231 const char *buf, size_t count)
234 bus->p->drivers_autoprobe = 0;
236 bus->p->drivers_autoprobe = 1;
240 static ssize_t store_drivers_probe(struct bus_type *bus,
241 const char *buf, size_t count)
245 dev = bus_find_device_by_name(bus, NULL, buf);
248 if (bus_rescan_devices_helper(dev, NULL) != 0)
254 static struct device *next_device(struct klist_iter *i)
256 struct klist_node *n = klist_next(i);
257 struct device *dev = NULL;
258 struct device_private *dev_prv;
261 dev_prv = to_device_private_bus(n);
262 dev = dev_prv->device;
268 * bus_for_each_dev - device iterator.
270 * @start: device to start iterating from.
271 * @data: data for the callback.
272 * @fn: function to be called for each device.
274 * Iterate over @bus's list of devices, and call @fn for each,
275 * passing it @data. If @start is not NULL, we use that device to
276 * begin iterating from.
278 * We check the return of @fn each time. If it returns anything
279 * other than 0, we break out and return that value.
281 * NOTE: The device that returns a non-zero value is not retained
282 * in any way, nor is its refcount incremented. If the caller needs
283 * to retain this data, it should do so, and increment the reference
284 * count in the supplied callback.
286 int bus_for_each_dev(struct bus_type *bus, struct device *start,
287 void *data, int (*fn)(struct device *, void *))
296 klist_iter_init_node(&bus->p->klist_devices, &i,
297 (start ? &start->p->knode_bus : NULL));
298 while ((dev = next_device(&i)) && !error)
299 error = fn(dev, data);
303 EXPORT_SYMBOL_GPL(bus_for_each_dev);
306 * bus_find_device - device iterator for locating a particular device.
308 * @start: Device to begin with
309 * @data: Data to pass to match function
310 * @match: Callback function to check device
312 * This is similar to the bus_for_each_dev() function above, but it
313 * returns a reference to a device that is 'found' for later use, as
314 * determined by the @match callback.
316 * The callback should return 0 if the device doesn't match and non-zero
317 * if it does. If the callback returns non-zero, this function will
318 * return to the caller and not iterate over any more devices.
320 struct device *bus_find_device(struct bus_type *bus,
321 struct device *start, void *data,
322 int (*match)(struct device *dev, void *data))
330 klist_iter_init_node(&bus->p->klist_devices, &i,
331 (start ? &start->p->knode_bus : NULL));
332 while ((dev = next_device(&i)))
333 if (match(dev, data) && get_device(dev))
338 EXPORT_SYMBOL_GPL(bus_find_device);
340 static int match_name(struct device *dev, void *data)
342 const char *name = data;
344 return sysfs_streq(name, dev_name(dev));
348 * bus_find_device_by_name - device iterator for locating a particular device of a specific name
350 * @start: Device to begin with
351 * @name: name of the device to match
353 * This is similar to the bus_find_device() function above, but it handles
354 * searching by a name automatically, no need to write another strcmp matching
357 struct device *bus_find_device_by_name(struct bus_type *bus,
358 struct device *start, const char *name)
360 return bus_find_device(bus, start, (void *)name, match_name);
362 EXPORT_SYMBOL_GPL(bus_find_device_by_name);
364 static struct device_driver *next_driver(struct klist_iter *i)
366 struct klist_node *n = klist_next(i);
367 struct driver_private *drv_priv;
370 drv_priv = container_of(n, struct driver_private, knode_bus);
371 return drv_priv->driver;
377 * bus_for_each_drv - driver iterator
378 * @bus: bus we're dealing with.
379 * @start: driver to start iterating on.
380 * @data: data to pass to the callback.
381 * @fn: function to call for each driver.
383 * This is nearly identical to the device iterator above.
384 * We iterate over each driver that belongs to @bus, and call
385 * @fn for each. If @fn returns anything but 0, we break out
386 * and return it. If @start is not NULL, we use it as the head
389 * NOTE: we don't return the driver that returns a non-zero
390 * value, nor do we leave the reference count incremented for that
391 * driver. If the caller needs to know that info, it must set it
392 * in the callback. It must also be sure to increment the refcount
393 * so it doesn't disappear before returning to the caller.
395 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
396 void *data, int (*fn)(struct device_driver *, void *))
399 struct device_driver *drv;
405 klist_iter_init_node(&bus->p->klist_drivers, &i,
406 start ? &start->p->knode_bus : NULL);
407 while ((drv = next_driver(&i)) && !error)
408 error = fn(drv, data);
412 EXPORT_SYMBOL_GPL(bus_for_each_drv);
414 static int device_add_attrs(struct bus_type *bus, struct device *dev)
422 for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
423 error = device_create_file(dev, &bus->dev_attrs[i]);
426 device_remove_file(dev, &bus->dev_attrs[i]);
433 static void device_remove_attrs(struct bus_type *bus, struct device *dev)
437 if (bus->dev_attrs) {
438 for (i = 0; attr_name(bus->dev_attrs[i]); i++)
439 device_remove_file(dev, &bus->dev_attrs[i]);
443 #ifdef CONFIG_SYSFS_DEPRECATED
444 static int make_deprecated_bus_links(struct device *dev)
446 return sysfs_create_link(&dev->kobj,
447 &dev->bus->p->subsys.kobj, "bus");
450 static void remove_deprecated_bus_links(struct device *dev)
452 sysfs_remove_link(&dev->kobj, "bus");
455 static inline int make_deprecated_bus_links(struct device *dev) { return 0; }
456 static inline void remove_deprecated_bus_links(struct device *dev) { }
460 * bus_add_device - add device to bus
461 * @dev: device being added
463 * - Add device's bus attributes.
464 * - Create links to device's bus.
465 * - Add the device to its bus's list of devices.
467 int bus_add_device(struct device *dev)
469 struct bus_type *bus = bus_get(dev->bus);
473 pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
474 error = device_add_attrs(bus, dev);
477 error = sysfs_create_link(&bus->p->devices_kset->kobj,
478 &dev->kobj, dev_name(dev));
481 error = sysfs_create_link(&dev->kobj,
482 &dev->bus->p->subsys.kobj, "subsystem");
485 error = make_deprecated_bus_links(dev);
488 klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
493 sysfs_remove_link(&dev->kobj, "subsystem");
495 sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
497 device_remove_attrs(bus, dev);
504 * bus_probe_device - probe drivers for a new device
505 * @dev: device to probe
507 * - Automatically probe for a driver if the bus allows it.
509 void bus_probe_device(struct device *dev)
511 struct bus_type *bus = dev->bus;
514 if (bus && bus->p->drivers_autoprobe) {
515 ret = device_attach(dev);
521 * bus_remove_device - remove device from bus
522 * @dev: device to be removed
524 * - Remove symlink from bus's directory.
525 * - Delete device from bus's list.
526 * - Detach from its driver.
527 * - Drop reference taken in bus_add_device().
529 void bus_remove_device(struct device *dev)
532 sysfs_remove_link(&dev->kobj, "subsystem");
533 remove_deprecated_bus_links(dev);
534 sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
536 device_remove_attrs(dev->bus, dev);
537 if (klist_node_attached(&dev->p->knode_bus))
538 klist_del(&dev->p->knode_bus);
540 pr_debug("bus: '%s': remove device %s\n",
541 dev->bus->name, dev_name(dev));
542 device_release_driver(dev);
547 static int driver_add_attrs(struct bus_type *bus, struct device_driver *drv)
552 if (bus->drv_attrs) {
553 for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
554 error = driver_create_file(drv, &bus->drv_attrs[i]);
563 driver_remove_file(drv, &bus->drv_attrs[i]);
567 static void driver_remove_attrs(struct bus_type *bus,
568 struct device_driver *drv)
572 if (bus->drv_attrs) {
573 for (i = 0; attr_name(bus->drv_attrs[i]); i++)
574 driver_remove_file(drv, &bus->drv_attrs[i]);
578 #ifdef CONFIG_HOTPLUG
580 * Thanks to drivers making their tables __devinit, we can't allow manual
581 * bind and unbind from userspace unless CONFIG_HOTPLUG is enabled.
583 static int __must_check add_bind_files(struct device_driver *drv)
587 ret = driver_create_file(drv, &driver_attr_unbind);
589 ret = driver_create_file(drv, &driver_attr_bind);
591 driver_remove_file(drv, &driver_attr_unbind);
596 static void remove_bind_files(struct device_driver *drv)
598 driver_remove_file(drv, &driver_attr_bind);
599 driver_remove_file(drv, &driver_attr_unbind);
602 static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
603 static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
604 show_drivers_autoprobe, store_drivers_autoprobe);
606 static int add_probe_files(struct bus_type *bus)
610 retval = bus_create_file(bus, &bus_attr_drivers_probe);
614 retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);
616 bus_remove_file(bus, &bus_attr_drivers_probe);
621 static void remove_probe_files(struct bus_type *bus)
623 bus_remove_file(bus, &bus_attr_drivers_autoprobe);
624 bus_remove_file(bus, &bus_attr_drivers_probe);
627 static inline int add_bind_files(struct device_driver *drv) { return 0; }
628 static inline void remove_bind_files(struct device_driver *drv) {}
629 static inline int add_probe_files(struct bus_type *bus) { return 0; }
630 static inline void remove_probe_files(struct bus_type *bus) {}
633 static ssize_t driver_uevent_store(struct device_driver *drv,
634 const char *buf, size_t count)
636 enum kobject_action action;
638 if (kobject_action_type(buf, count, &action) == 0)
639 kobject_uevent(&drv->p->kobj, action);
642 static DRIVER_ATTR(uevent, S_IWUSR, NULL, driver_uevent_store);
645 * bus_add_driver - Add a driver to the bus.
648 int bus_add_driver(struct device_driver *drv)
650 struct bus_type *bus;
651 struct driver_private *priv;
654 bus = bus_get(drv->bus);
658 pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
660 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
665 klist_init(&priv->klist_devices, NULL, NULL);
668 priv->kobj.kset = bus->p->drivers_kset;
669 error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
674 if (drv->bus->p->drivers_autoprobe) {
675 error = driver_attach(drv);
679 klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
680 module_add_driver(drv->owner, drv);
682 error = driver_create_file(drv, &driver_attr_uevent);
684 printk(KERN_ERR "%s: uevent attr (%s) failed\n",
685 __func__, drv->name);
687 error = driver_add_attrs(bus, drv);
689 /* How the hell do we get out of this pickle? Give up */
690 printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n",
691 __func__, drv->name);
694 if (!drv->suppress_bind_attrs) {
695 error = add_bind_files(drv);
698 printk(KERN_ERR "%s: add_bind_files(%s) failed\n",
699 __func__, drv->name);
703 kobject_uevent(&priv->kobj, KOBJ_ADD);
707 kobject_put(&priv->kobj);
716 * bus_remove_driver - delete driver from bus's knowledge.
719 * Detach the driver from the devices it controls, and remove
720 * it from its bus's list of drivers. Finally, we drop the reference
721 * to the bus we took in bus_add_driver().
723 void bus_remove_driver(struct device_driver *drv)
728 if (!drv->suppress_bind_attrs)
729 remove_bind_files(drv);
730 driver_remove_attrs(drv->bus, drv);
731 driver_remove_file(drv, &driver_attr_uevent);
732 klist_remove(&drv->p->knode_bus);
733 pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
735 module_remove_driver(drv);
736 kobject_put(&drv->p->kobj);
740 /* Helper for bus_rescan_devices's iter */
741 static int __must_check bus_rescan_devices_helper(struct device *dev,
747 if (dev->parent) /* Needed for USB */
748 device_lock(dev->parent);
749 ret = device_attach(dev);
751 device_unlock(dev->parent);
753 return ret < 0 ? ret : 0;
757 * bus_rescan_devices - rescan devices on the bus for possible drivers
758 * @bus: the bus to scan.
760 * This function will look for devices on the bus with no driver
761 * attached and rescan it against existing drivers to see if it matches
762 * any by calling device_attach() for the unbound devices.
764 int bus_rescan_devices(struct bus_type *bus)
766 return bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
768 EXPORT_SYMBOL_GPL(bus_rescan_devices);
771 * device_reprobe - remove driver for a device and probe for a new driver
772 * @dev: the device to reprobe
774 * This function detaches the attached driver (if any) for the given
775 * device and restarts the driver probing process. It is intended
776 * to use if probing criteria changed during a devices lifetime and
777 * driver attachment should change accordingly.
779 int device_reprobe(struct device *dev)
782 if (dev->parent) /* Needed for USB */
783 device_lock(dev->parent);
784 device_release_driver(dev);
786 device_unlock(dev->parent);
788 return bus_rescan_devices_helper(dev, NULL);
790 EXPORT_SYMBOL_GPL(device_reprobe);
793 * find_bus - locate bus by name.
794 * @name: name of bus.
796 * Call kset_find_obj() to iterate over list of buses to
797 * find a bus by name. Return bus if found.
799 * Note that kset_find_obj increments bus' reference count.
802 struct bus_type *find_bus(char *name)
804 struct kobject *k = kset_find_obj(bus_kset, name);
805 return k ? to_bus(k) : NULL;
811 * bus_add_attrs - Add default attributes for this bus.
812 * @bus: Bus that has just been registered.
815 static int bus_add_attrs(struct bus_type *bus)
820 if (bus->bus_attrs) {
821 for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
822 error = bus_create_file(bus, &bus->bus_attrs[i]);
831 bus_remove_file(bus, &bus->bus_attrs[i]);
835 static void bus_remove_attrs(struct bus_type *bus)
839 if (bus->bus_attrs) {
840 for (i = 0; attr_name(bus->bus_attrs[i]); i++)
841 bus_remove_file(bus, &bus->bus_attrs[i]);
845 static void klist_devices_get(struct klist_node *n)
847 struct device_private *dev_prv = to_device_private_bus(n);
848 struct device *dev = dev_prv->device;
853 static void klist_devices_put(struct klist_node *n)
855 struct device_private *dev_prv = to_device_private_bus(n);
856 struct device *dev = dev_prv->device;
861 static ssize_t bus_uevent_store(struct bus_type *bus,
862 const char *buf, size_t count)
864 enum kobject_action action;
866 if (kobject_action_type(buf, count, &action) == 0)
867 kobject_uevent(&bus->p->subsys.kobj, action);
870 static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
873 * bus_register - register a bus with the system.
876 * Once we have that, we registered the bus with the kobject
877 * infrastructure, then register the children subsystems it has:
878 * the devices and drivers that belong to the bus.
880 int bus_register(struct bus_type *bus)
883 struct bus_type_private *priv;
885 priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);
892 BLOCKING_INIT_NOTIFIER_HEAD(&priv->bus_notifier);
894 retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);
898 priv->subsys.kobj.kset = bus_kset;
899 priv->subsys.kobj.ktype = &bus_ktype;
900 priv->drivers_autoprobe = 1;
902 retval = kset_register(&priv->subsys);
906 retval = bus_create_file(bus, &bus_attr_uevent);
908 goto bus_uevent_fail;
910 priv->devices_kset = kset_create_and_add("devices", NULL,
912 if (!priv->devices_kset) {
914 goto bus_devices_fail;
917 priv->drivers_kset = kset_create_and_add("drivers", NULL,
919 if (!priv->drivers_kset) {
921 goto bus_drivers_fail;
924 klist_init(&priv->klist_devices, klist_devices_get, klist_devices_put);
925 klist_init(&priv->klist_drivers, NULL, NULL);
927 retval = add_probe_files(bus);
929 goto bus_probe_files_fail;
931 retval = bus_add_attrs(bus);
935 pr_debug("bus: '%s': registered\n", bus->name);
939 remove_probe_files(bus);
940 bus_probe_files_fail:
941 kset_unregister(bus->p->drivers_kset);
943 kset_unregister(bus->p->devices_kset);
945 bus_remove_file(bus, &bus_attr_uevent);
947 kset_unregister(&bus->p->subsys);
953 EXPORT_SYMBOL_GPL(bus_register);
956 * bus_unregister - remove a bus from the system
959 * Unregister the child subsystems and the bus itself.
960 * Finally, we call bus_put() to release the refcount
962 void bus_unregister(struct bus_type *bus)
964 pr_debug("bus: '%s': unregistering\n", bus->name);
965 bus_remove_attrs(bus);
966 remove_probe_files(bus);
967 kset_unregister(bus->p->drivers_kset);
968 kset_unregister(bus->p->devices_kset);
969 bus_remove_file(bus, &bus_attr_uevent);
970 kset_unregister(&bus->p->subsys);
974 EXPORT_SYMBOL_GPL(bus_unregister);
976 int bus_register_notifier(struct bus_type *bus, struct notifier_block *nb)
978 return blocking_notifier_chain_register(&bus->p->bus_notifier, nb);
980 EXPORT_SYMBOL_GPL(bus_register_notifier);
982 int bus_unregister_notifier(struct bus_type *bus, struct notifier_block *nb)
984 return blocking_notifier_chain_unregister(&bus->p->bus_notifier, nb);
986 EXPORT_SYMBOL_GPL(bus_unregister_notifier);
988 struct kset *bus_get_kset(struct bus_type *bus)
990 return &bus->p->subsys;
992 EXPORT_SYMBOL_GPL(bus_get_kset);
994 struct klist *bus_get_device_klist(struct bus_type *bus)
996 return &bus->p->klist_devices;
998 EXPORT_SYMBOL_GPL(bus_get_device_klist);
1001 * Yes, this forcably breaks the klist abstraction temporarily. It
1002 * just wants to sort the klist, not change reference counts and
1003 * take/drop locks rapidly in the process. It does all this while
1004 * holding the lock for the list, so objects can't otherwise be
1005 * added/removed while we're swizzling.
1007 static void device_insertion_sort_klist(struct device *a, struct list_head *list,
1008 int (*compare)(const struct device *a,
1009 const struct device *b))
1011 struct list_head *pos;
1012 struct klist_node *n;
1013 struct device_private *dev_prv;
1016 list_for_each(pos, list) {
1017 n = container_of(pos, struct klist_node, n_node);
1018 dev_prv = to_device_private_bus(n);
1019 b = dev_prv->device;
1020 if (compare(a, b) <= 0) {
1021 list_move_tail(&a->p->knode_bus.n_node,
1022 &b->p->knode_bus.n_node);
1026 list_move_tail(&a->p->knode_bus.n_node, list);
1029 void bus_sort_breadthfirst(struct bus_type *bus,
1030 int (*compare)(const struct device *a,
1031 const struct device *b))
1033 LIST_HEAD(sorted_devices);
1034 struct list_head *pos, *tmp;
1035 struct klist_node *n;
1036 struct device_private *dev_prv;
1038 struct klist *device_klist;
1040 device_klist = bus_get_device_klist(bus);
1042 spin_lock(&device_klist->k_lock);
1043 list_for_each_safe(pos, tmp, &device_klist->k_list) {
1044 n = container_of(pos, struct klist_node, n_node);
1045 dev_prv = to_device_private_bus(n);
1046 dev = dev_prv->device;
1047 device_insertion_sort_klist(dev, &sorted_devices, compare);
1049 list_splice(&sorted_devices, &device_klist->k_list);
1050 spin_unlock(&device_klist->k_lock);
1052 EXPORT_SYMBOL_GPL(bus_sort_breadthfirst);
1054 int __init buses_init(void)
1056 bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);