// SPDX-License-Identifier: GPL-2.0/* * bus.c - bus driver management * * Copyright (c) 2002-3 Patrick Mochel * Copyright (c) 2002-3 Open Source Development Labs * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de> * Copyright (c) 2007 Novell Inc. * Copyright (c) 2023 Greg Kroah-Hartman <gregkh@linuxfoundation.org> */ #include <linux/async.h>#include <linux/device/bus.h>#include <linux/device.h>#include <linux/module.h>#include <linux/errno.h>#include <linux/slab.h>#include <linux/init.h>#include <linux/string.h>#include <linux/mutex.h>#include <linux/sysfs.h>#include "base.h"#include "power/power.h" /* /sys/devices/system */static struct kset *system_kset; /* /sys/bus */static struct kset *bus_kset; #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr) /* * sysfs bindings for drivers */ #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr) #define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \ struct driver_attribute driver_attr_##_name = \ __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) static int __must_check bus_rescan_devices_helper(struct device *dev, void *data); /** * bus_to_subsys - Turn a struct bus_type into a struct subsys_private * * @bus: pointer to the struct bus_type to look up * * The driver core internals needs to work on the subsys_private structure, not * the external struct bus_type pointer. This function walks the list of * registered busses in the system and finds the matching one and returns the * internal struct subsys_private that relates to that bus. * * Note, the reference count of the return value is INCREMENTED if it is not * NULL. A call to subsys_put() must be done when finished with the pointer in * order for it to be properly freed. */struct subsys_private *bus_to_subsys(const struct bus_type *bus){ struct subsys_private *sp = NULL; struct kobject *kobj; if (!bus || !bus_kset) return NULL; spin_lock(&bus_kset->list_lock); if (list_empty(&bus_kset->list)) goto done; list_for_each_entry(kobj, &bus_kset->list, entry) { struct kset *kset = container_of(kobj, struct kset, kobj); sp = container_of_const(kset, struct subsys_private, subsys); if (sp->bus == bus) goto done; } sp = NULL;done: sp = subsys_get(sp); spin_unlock(&bus_kset->list_lock); return sp;} static const struct bus_type *bus_get(const struct bus_type *bus){ struct subsys_private *sp = bus_to_subsys(bus); if (sp) return bus; return NULL;} static void bus_put(const struct bus_type *bus){ struct subsys_private *sp = bus_to_subsys(bus); /* two puts are required as the call to bus_to_subsys incremented it again */ subsys_put(sp); subsys_put(sp);} static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr, char *buf){ struct driver_attribute *drv_attr = to_drv_attr(attr); struct driver_private *drv_priv = to_driver(kobj); ssize_t ret = -EIO; if (drv_attr->show) ret = drv_attr->show(drv_priv->driver, buf); return ret;} static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count){ struct driver_attribute *drv_attr = to_drv_attr(attr); struct driver_private *drv_priv = to_driver(kobj); ssize_t ret = -EIO; if (drv_attr->store) ret = drv_attr->store(drv_priv->driver, buf, count); return ret;} static const struct sysfs_ops driver_sysfs_ops = { .show = drv_attr_show, .store = drv_attr_store,}; static void driver_release(struct kobject *kobj){ struct driver_private *drv_priv = to_driver(kobj); pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__); kfree(drv_priv);} static const struct kobj_type driver_ktype = { .sysfs_ops = &driver_sysfs_ops, .release = driver_release,}; /* * sysfs bindings for buses */static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr, char *buf){ struct bus_attribute *bus_attr = to_bus_attr(attr); struct subsys_private *subsys_priv = to_subsys_private(kobj); /* return -EIO for reading a bus attribute without show() */ ssize_t ret = -EIO; if (bus_attr->show) ret = bus_attr->show(subsys_priv->bus, buf); return ret;} static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count){ struct bus_attribute *bus_attr = to_bus_attr(attr); struct subsys_private *subsys_priv = to_subsys_private(kobj); /* return -EIO for writing a bus attribute without store() */ ssize_t ret = -EIO; if (bus_attr->store) ret = bus_attr->store(subsys_priv->bus, buf, count); return ret;} static const struct sysfs_ops bus_sysfs_ops = { .show = bus_attr_show, .store = bus_attr_store,}; int bus_create_file(const struct bus_type *bus, struct bus_attribute *attr){ struct subsys_private *sp = bus_to_subsys(bus); int error; if (!sp) return -EINVAL; error = sysfs_create_file(&sp->subsys.kobj, &attr->attr); subsys_put(sp); return error;}EXPORT_SYMBOL_GPL(bus_create_file); void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr){ struct subsys_private *sp = bus_to_subsys(bus); if (!sp) return; sysfs_remove_file(&sp->subsys.kobj, &attr->attr); subsys_put(sp);}EXPORT_SYMBOL_GPL(bus_remove_file); static void bus_release(struct kobject *kobj){ struct subsys_private *priv = to_subsys_private(kobj); lockdep_unregister_key(&priv->lock_key); kfree(priv);} static const struct kobj_type bus_ktype = { .sysfs_ops = &bus_sysfs_ops, .release = bus_release,}; static int bus_uevent_filter(const struct kobject *kobj){ const struct kobj_type *ktype = get_ktype(kobj); if (ktype == &bus_ktype) return 1; return 0;} static const struct kset_uevent_ops bus_uevent_ops = { .filter = bus_uevent_filter,}; /* Manually detach a device from its associated driver. */static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t count){ const struct bus_type *bus = bus_get(drv->bus); struct device *dev; int err = -ENODEV; dev = bus_find_device_by_name(bus, NULL, buf); if (dev && dev->driver == drv) { device_driver_detach(dev); err = count; } put_device(dev); bus_put(bus); return err;}static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store); /* * Manually attach a device to a driver. * Note: the driver must want to bind to the device, * it is not possible to override the driver's id table. */static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t count){ const struct bus_type *bus = bus_get(drv->bus); struct device *dev; int err = -ENODEV; dev = bus_find_device_by_name(bus, NULL, buf); if (dev && driver_match_device(drv, dev)) { err = device_driver_attach(drv, dev); if (!err) { /* success */ err = count; } } put_device(dev); bus_put(bus); return err;}static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store); static ssize_t drivers_autoprobe_show(const struct bus_type *bus, char *buf){ struct subsys_private *sp = bus_to_subsys(bus); int ret; if (!sp) return -EINVAL; ret = sysfs_emit(buf, "%d\n", sp->drivers_autoprobe); subsys_put(sp); return ret;} static ssize_t drivers_autoprobe_store(const struct bus_type *bus, const char *buf, size_t count){ struct subsys_private *sp = bus_to_subsys(bus); if (!sp) return -EINVAL; if (buf[0] == '0') sp->drivers_autoprobe = 0; else sp->drivers_autoprobe = 1; subsys_put(sp); return count;} static ssize_t drivers_probe_store(const struct bus_type *bus, const char *buf, size_t count){ struct device *dev; int err = -EINVAL; dev = bus_find_device_by_name(bus, NULL, buf); if (!dev) return -ENODEV; if (bus_rescan_devices_helper(dev, NULL) == 0) err = count; put_device(dev); return err;} static struct device *next_device(struct klist_iter *i){ struct klist_node *n = klist_next(i); struct device *dev = NULL; struct device_private *dev_prv; if (n) { dev_prv = to_device_private_bus(n); dev = dev_prv->device; } return dev;} static struct device *prev_device(struct klist_iter *i){ struct klist_node *n = klist_prev(i); struct device *dev = NULL; struct device_private *dev_prv; if (n) { dev_prv = to_device_private_bus(n); dev = dev_prv->device; } return dev;} /** * bus_for_each_dev - device iterator. * @bus: bus type. * @start: device to start iterating from. * @data: data for the callback. * @fn: function to be called for each device. * * Iterate over @bus's list of devices, and call @fn for each, * passing it @data. If @start is not NULL, we use that device to * begin iterating from. * * We check the return of @fn each time. If it returns anything * other than 0, we break out and return that value. * * NOTE: The device that returns a non-zero value is not retained * in any way, nor is its refcount incremented. If the caller needs * to retain this data, it should do so, and increment the reference * count in the supplied callback. */int bus_for_each_dev(const struct bus_type *bus, struct device *start, void *data, device_iter_t fn){ struct subsys_private *sp = bus_to_subsys(bus); struct klist_iter i; struct device *dev; int error = 0; if (!sp) return -EINVAL; klist_iter_init_node(&sp->klist_devices, &i, (start ? &start->p->knode_bus : NULL)); while (!error && (dev = next_device(&i))) error = fn(dev, data); klist_iter_exit(&i); subsys_put(sp); return error;}EXPORT_SYMBOL_GPL(bus_for_each_dev); /** * bus_find_device - device iterator for locating a particular device. * @bus: bus type * @start: Device to begin with * @data: Data to pass to match function * @match: Callback function to check device * * This is similar to the bus_for_each_dev() function above, but it * returns a reference to a device that is 'found' for later use, as * determined by the @match callback. * * The callback should return 0 if the device doesn't match and non-zero * if it does. If the callback returns non-zero, this function will * return to the caller and not iterate over any more devices. */struct device *bus_find_device(const struct bus_type *bus, struct device *start, const void *data, device_match_t match){ struct subsys_private *sp = bus_to_subsys(bus); struct klist_iter i; struct device *dev; if (!sp) return NULL; klist_iter_init_node(&sp->klist_devices, &i, (start ? &start->p->knode_bus : NULL)); while ((dev = next_device(&i))) { if (match(dev, data)) { get_device(dev); break; } } klist_iter_exit(&i); subsys_put(sp); return dev;}EXPORT_SYMBOL_GPL(bus_find_device); struct device *bus_find_device_reverse(const struct bus_type *bus, struct device *start, const void *data, device_match_t match){ struct subsys_private *sp = bus_to_subsys(bus); struct klist_iter i; struct device *dev; if (!sp) return NULL; klist_iter_init_node(&sp->klist_devices, &i, (start ? &start->p->knode_bus : NULL)); while ((dev = prev_device(&i))) { if (match(dev, data)) { get_device(dev); break; } } klist_iter_exit(&i); subsys_put(sp); return dev;}EXPORT_SYMBOL_GPL(bus_find_device_reverse); static struct device_driver *next_driver(struct klist_iter *i){ struct klist_node *n = klist_next(i); struct driver_private *drv_priv; if (n) { drv_priv = container_of(n, struct driver_private, knode_bus); return drv_priv->driver; } return NULL;} /** * bus_for_each_drv - driver iterator * @bus: bus we're dealing with. * @start: driver to start iterating on. * @data: data to pass to the callback. * @fn: function to call for each driver. * * This is nearly identical to the device iterator above. * We iterate over each driver that belongs to @bus, and call * @fn for each. If @fn returns anything but 0, we break out * and return it. If @start is not NULL, we use it as the head * of the list. * * NOTE: we don't return the driver that returns a non-zero * value, nor do we leave the reference count incremented for that * driver. If the caller needs to know that info, it must set it * in the callback. It must also be sure to increment the refcount * so it doesn't disappear before returning to the caller. */int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start, void *data, int (*fn)(struct device_driver *, void *)){ struct subsys_private *sp = bus_to_subsys(bus); struct klist_iter i; struct device_driver *drv; int error = 0; if (!sp) return -EINVAL; klist_iter_init_node(&sp->klist_drivers, &i, start ? &start->p->knode_bus : NULL); while ((drv = next_driver(&i)) && !error) error = fn(drv, data);Lines 1–500 of 1489. Load more
// SPDX-License-Identifier: GPL-2.0 /* * bus.c - bus driver management * * Copyright (c) 2002-3 Patrick Mochel * Copyright (c) 2002-3 Open Source Development Labs * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de> * Copyright (c) 2007 Novell Inc. * Copyright (c) 2023 Greg Kroah-Hartman <gregkh@linuxfoundation.org> */ #include <linux/async.h> #include <linux/device/bus.h> #include <linux/device.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/slab.h> #include <linux/init.h> #include <linux/string.h> #include <linux/mutex.h> #include <linux/sysfs.h> #include "base.h" #include "power/power.h" /* /sys/devices/system */ static struct kset *system_kset; /* /sys/bus */ static struct kset *bus_kset; #define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr) /* * sysfs bindings for drivers */ #define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr) #define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \ struct driver_attribute driver_attr_##_name = \ __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) static int __must_check bus_rescan_devices_helper(struct device *dev, void *data); /** * bus_to_subsys - Turn a struct bus_type into a struct subsys_private * * @bus: pointer to the struct bus_type to look up * * The driver core internals needs to work on the subsys_private structure, not * the external struct bus_type pointer. This function walks the list of * registered busses in the system and finds the matching one and returns the * internal struct subsys_private that relates to that bus. * * Note, the reference count of the return value is INCREMENTED if it is not * NULL. A call to subsys_put() must be done when finished with the pointer in * order for it to be properly freed. */ struct subsys_private *bus_to_subsys(const struct bus_type *bus) { struct subsys_private *sp = NULL; struct kobject *kobj; if (!bus || !bus_kset) return NULL; spin_lock(&bus_kset->list_lock); if (list_empty(&bus_kset->list)) goto done; list_for_each_entry(kobj, &bus_kset->list, entry) { struct kset *kset = container_of(kobj, struct kset, kobj); sp = container_of_const(kset, struct subsys_private, subsys); if (sp->bus == bus) goto done; } sp = NULL; done: sp = subsys_get(sp); spin_unlock(&bus_kset->list_lock); return sp; } static const struct bus_type *bus_get(const struct bus_type *bus) { struct subsys_private *sp = bus_to_subsys(bus); if (sp) return bus; return NULL; } static void bus_put(const struct bus_type *bus) { struct subsys_private *sp = bus_to_subsys(bus); /* two puts are required as the call to bus_to_subsys incremented it again */ subsys_put(sp); subsys_put(sp); } static ssize_t drv_attr_show(struct kobject *kobj, struct attribute *attr, char *buf) { struct driver_attribute *drv_attr = to_drv_attr(attr); struct driver_private *drv_priv = to_driver(kobj); ssize_t ret = -EIO; if (drv_attr->show) ret = drv_attr->show(drv_priv->driver, buf); return ret; } static ssize_t drv_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count) { struct driver_attribute *drv_attr = to_drv_attr(attr); struct driver_private *drv_priv = to_driver(kobj); ssize_t ret = -EIO; if (drv_attr->store) ret = drv_attr->store(drv_priv->driver, buf, count); return ret; } static const struct sysfs_ops driver_sysfs_ops = { .show = drv_attr_show, .store = drv_attr_store, }; static void driver_release(struct kobject *kobj) { struct driver_private *drv_priv = to_driver(kobj); pr_debug("driver: '%s': %s\n", kobject_name(kobj), __func__); kfree(drv_priv); } static const struct kobj_type driver_ktype = { .sysfs_ops = &driver_sysfs_ops, .release = driver_release, }; /* * sysfs bindings for buses */ static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr, char *buf) { struct bus_attribute *bus_attr = to_bus_attr(attr); struct subsys_private *subsys_priv = to_subsys_private(kobj); /* return -EIO for reading a bus attribute without show() */ ssize_t ret = -EIO; if (bus_attr->show) ret = bus_attr->show(subsys_priv->bus, buf); return ret; } static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count) { struct bus_attribute *bus_attr = to_bus_attr(attr); struct subsys_private *subsys_priv = to_subsys_private(kobj); /* return -EIO for writing a bus attribute without store() */ ssize_t ret = -EIO; if (bus_attr->store) ret = bus_attr->store(subsys_priv->bus, buf, count); return ret; } static const struct sysfs_ops bus_sysfs_ops = { .show = bus_attr_show, .store = bus_attr_store, }; int bus_create_file(const struct bus_type *bus, struct bus_attribute *attr) { struct subsys_private *sp = bus_to_subsys(bus); int error; if (!sp) return -EINVAL; error = sysfs_create_file(&sp->subsys.kobj, &attr->attr); subsys_put(sp); return error; } EXPORT_SYMBOL_GPL(bus_create_file); void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr) { struct subsys_private *sp = bus_to_subsys(bus); if (!sp) return; sysfs_remove_file(&sp->subsys.kobj, &attr->attr); subsys_put(sp); } EXPORT_SYMBOL_GPL(bus_remove_file); static void bus_release(struct kobject *kobj) { struct subsys_private *priv = to_subsys_private(kobj); lockdep_unregister_key(&priv->lock_key); kfree(priv); } static const struct kobj_type bus_ktype = { .sysfs_ops = &bus_sysfs_ops, .release = bus_release, }; static int bus_uevent_filter(const struct kobject *kobj) { const struct kobj_type *ktype = get_ktype(kobj); if (ktype == &bus_ktype) return 1; return 0; } static const struct kset_uevent_ops bus_uevent_ops = { .filter = bus_uevent_filter, }; /* Manually detach a device from its associated driver. */ static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t count) { const struct bus_type *bus = bus_get(drv->bus); struct device *dev; int err = -ENODEV; dev = bus_find_device_by_name(bus, NULL, buf); if (dev && dev->driver == drv) { device_driver_detach(dev); err = count; } put_device(dev); bus_put(bus); return err; } static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store); /* * Manually attach a device to a driver. * Note: the driver must want to bind to the device, * it is not possible to override the driver's id table. */ static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t count) { const struct bus_type *bus = bus_get(drv->bus); struct device *dev; int err = -ENODEV; dev = bus_find_device_by_name(bus, NULL, buf); if (dev && driver_match_device(drv, dev)) { err = device_driver_attach(drv, dev); if (!err) { /* success */ err = count; } } put_device(dev); bus_put(bus); return err; } static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store); static ssize_t drivers_autoprobe_show(const struct bus_type *bus, char *buf) { struct subsys_private *sp = bus_to_subsys(bus); int ret; if (!sp) return -EINVAL; ret = sysfs_emit(buf, "%d\n", sp->drivers_autoprobe); subsys_put(sp); return ret; } static ssize_t drivers_autoprobe_store(const struct bus_type *bus, const char *buf, size_t count) { struct subsys_private *sp = bus_to_subsys(bus); if (!sp) return -EINVAL; if (buf[0] == '0') sp->drivers_autoprobe = 0; else sp->drivers_autoprobe = 1; subsys_put(sp); return count; } static ssize_t drivers_probe_store(const struct bus_type *bus, const char *buf, size_t count) { struct device *dev; int err = -EINVAL; dev = bus_find_device_by_name(bus, NULL, buf); if (!dev) return -ENODEV; if (bus_rescan_devices_helper(dev, NULL) == 0) err = count; put_device(dev); return err; } static struct device *next_device(struct klist_iter *i) { struct klist_node *n = klist_next(i); struct device *dev = NULL; struct device_private *dev_prv; if (n) { dev_prv = to_device_private_bus(n); dev = dev_prv->device; } return dev; } static struct device *prev_device(struct klist_iter *i) { struct klist_node *n = klist_prev(i); struct device *dev = NULL; struct device_private *dev_prv; if (n) { dev_prv = to_device_private_bus(n); dev = dev_prv->device; } return dev; } /** * bus_for_each_dev - device iterator. * @bus: bus type. * @start: device to start iterating from. * @data: data for the callback. * @fn: function to be called for each device. * * Iterate over @bus's list of devices, and call @fn for each, * passing it @data. If @start is not NULL, we use that device to * begin iterating from. * * We check the return of @fn each time. If it returns anything * other than 0, we break out and return that value. * * NOTE: The device that returns a non-zero value is not retained * in any way, nor is its refcount incremented. If the caller needs * to retain this data, it should do so, and increment the reference * count in the supplied callback. */ int bus_for_each_dev(const struct bus_type *bus, struct device *start, void *data, device_iter_t fn) { struct subsys_private *sp = bus_to_subsys(bus); struct klist_iter i; struct device *dev; int error = 0; if (!sp) return -EINVAL; klist_iter_init_node(&sp->klist_devices, &i, (start ? &start->p->knode_bus : NULL)); while (!error && (dev = next_device(&i))) error = fn(dev, data); klist_iter_exit(&i); subsys_put(sp); return error; } EXPORT_SYMBOL_GPL(bus_for_each_dev); /** * bus_find_device - device iterator for locating a particular device. * @bus: bus type * @start: Device to begin with * @data: Data to pass to match function * @match: Callback function to check device * * This is similar to the bus_for_each_dev() function above, but it * returns a reference to a device that is 'found' for later use, as * determined by the @match callback. * * The callback should return 0 if the device doesn't match and non-zero * if it does. If the callback returns non-zero, this function will * return to the caller and not iterate over any more devices. */ struct device *bus_find_device(const struct bus_type *bus, struct device *start, const void *data, device_match_t match) { struct subsys_private *sp = bus_to_subsys(bus); struct klist_iter i; struct device *dev; if (!sp) return NULL; klist_iter_init_node(&sp->klist_devices, &i, (start ? &start->p->knode_bus : NULL)); while ((dev = next_device(&i))) { if (match(dev, data)) { get_device(dev); break; } } klist_iter_exit(&i); subsys_put(sp); return dev; } EXPORT_SYMBOL_GPL(bus_find_device); struct device *bus_find_device_reverse(const struct bus_type *bus, struct device *start, const void *data, device_match_t match) { struct subsys_private *sp = bus_to_subsys(bus); struct klist_iter i; struct device *dev; if (!sp) return NULL; klist_iter_init_node(&sp->klist_devices, &i, (start ? &start->p->knode_bus : NULL)); while ((dev = prev_device(&i))) { if (match(dev, data)) { get_device(dev); break; } } klist_iter_exit(&i); subsys_put(sp); return dev; } EXPORT_SYMBOL_GPL(bus_find_device_reverse); static struct device_driver *next_driver(struct klist_iter *i) { struct klist_node *n = klist_next(i); struct driver_private *drv_priv; if (n) { drv_priv = container_of(n, struct driver_private, knode_bus); return drv_priv->driver; } return NULL; } /** * bus_for_each_drv - driver iterator * @bus: bus we're dealing with. * @start: driver to start iterating on. * @data: data to pass to the callback. * @fn: function to call for each driver. * * This is nearly identical to the device iterator above. * We iterate over each driver that belongs to @bus, and call * @fn for each. If @fn returns anything but 0, we break out * and return it. If @start is not NULL, we use it as the head * of the list. * * NOTE: we don't return the driver that returns a non-zero * value, nor do we leave the reference count incremented for that * driver. If the caller needs to know that info, it must set it * in the callback. It must also be sure to increment the refcount * so it doesn't disappear before returning to the caller. */ int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start, void *data, int (*fn)(struct device_driver *, void *)) { struct subsys_private *sp = bus_to_subsys(bus); struct klist_iter i; struct device_driver *drv; int error = 0; if (!sp) return -EINVAL; klist_iter_init_node(&sp->klist_drivers, &i, start ? &start->p->knode_bus : NULL); while ((drv = next_driver(&i)) && !error) error = fn(drv, data);