kernel-ark/drivers/base/bus.c
James Bottomley 34bb61f9dd [PATCH] fix klist semantics for lists which have elements removed on traversal
The problem is that klists claim to provide semantics for safe traversal of
lists which are being modified.  The failure case is when traversal of a
list causes element removal (a fairly common case).  The issue is that
although the list node is refcounted, if it is embedded in an object (which
is universally the case), then the object will be freed regardless of the
klist refcount leading to slab corruption because the klist iterator refers
to the prior element to get the next.

The solution is to make the klist take and release references to the
embedding object meaning that the embedding object won't be released until
the list relinquishes the reference to it.

(akpm: fast-track this because it's needed for the 2.6.13 scsi merge)

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07 18:26:54 -07:00

688 lines
16 KiB
C

/*
* bus.c - bus driver management
*
* Copyright (c) 2002-3 Patrick Mochel
* Copyright (c) 2002-3 Open Source Development Labs
*
* This file is released under the GPLv2
*
*/
#include <linux/config.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/string.h>
#include "base.h"
#include "power/power.h"
#define to_bus_attr(_attr) container_of(_attr, struct bus_attribute, attr)
#define to_bus(obj) container_of(obj, struct bus_type, subsys.kset.kobj)
/*
* sysfs bindings for drivers
*/
#define to_drv_attr(_attr) container_of(_attr, struct driver_attribute, attr)
#define to_driver(obj) container_of(obj, struct device_driver, kobj)
static ssize_t
drv_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
{
struct driver_attribute * drv_attr = to_drv_attr(attr);
struct device_driver * drv = to_driver(kobj);
ssize_t ret = -EIO;
if (drv_attr->show)
ret = drv_attr->show(drv, 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 device_driver * drv = to_driver(kobj);
ssize_t ret = -EIO;
if (drv_attr->store)
ret = drv_attr->store(drv, buf, count);
return ret;
}
static struct sysfs_ops driver_sysfs_ops = {
.show = drv_attr_show,
.store = drv_attr_store,
};
static void driver_release(struct kobject * kobj)
{
struct device_driver * drv = to_driver(kobj);
complete(&drv->unloaded);
}
static struct kobj_type ktype_driver = {
.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 bus_type * bus = to_bus(kobj);
ssize_t ret = 0;
if (bus_attr->show)
ret = bus_attr->show(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 bus_type * bus = to_bus(kobj);
ssize_t ret = 0;
if (bus_attr->store)
ret = bus_attr->store(bus, buf, count);
return ret;
}
static struct sysfs_ops bus_sysfs_ops = {
.show = bus_attr_show,
.store = bus_attr_store,
};
int bus_create_file(struct bus_type * bus, struct bus_attribute * attr)
{
int error;
if (get_bus(bus)) {
error = sysfs_create_file(&bus->subsys.kset.kobj, &attr->attr);
put_bus(bus);
} else
error = -EINVAL;
return error;
}
void bus_remove_file(struct bus_type * bus, struct bus_attribute * attr)
{
if (get_bus(bus)) {
sysfs_remove_file(&bus->subsys.kset.kobj, &attr->attr);
put_bus(bus);
}
}
static struct kobj_type ktype_bus = {
.sysfs_ops = &bus_sysfs_ops,
};
decl_subsys(bus, &ktype_bus, NULL);
/* Manually detach a device from it's associated driver. */
static int driver_helper(struct device *dev, void *data)
{
const char *name = data;
if (strcmp(name, dev->bus_id) == 0)
return 1;
return 0;
}
static ssize_t driver_unbind(struct device_driver *drv,
const char *buf, size_t count)
{
struct bus_type *bus = get_bus(drv->bus);
struct device *dev;
int err = -ENODEV;
dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
if ((dev) &&
(dev->driver == drv)) {
device_release_driver(dev);
err = count;
}
if (err)
return err;
return count;
}
static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
/*
* 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 driver_bind(struct device_driver *drv,
const char *buf, size_t count)
{
struct bus_type *bus = get_bus(drv->bus);
struct device *dev;
int err = -ENODEV;
dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
if ((dev) &&
(dev->driver == NULL)) {
down(&dev->sem);
err = driver_probe_device(drv, dev);
up(&dev->sem);
put_device(dev);
}
if (err)
return err;
return count;
}
static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
static struct device * next_device(struct klist_iter * i)
{
struct klist_node * n = klist_next(i);
return n ? container_of(n, struct device, knode_bus) : NULL;
}
/**
* 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, and increment the reference
* count in the supplied callback.
*/
int bus_for_each_dev(struct bus_type * bus, struct device * start,
void * data, int (*fn)(struct device *, void *))
{
struct klist_iter i;
struct device * dev;
int error = 0;
if (!bus)
return -EINVAL;
klist_iter_init_node(&bus->klist_devices, &i,
(start ? &start->knode_bus : NULL));
while ((dev = next_device(&i)) && !error)
error = fn(dev, data);
klist_iter_exit(&i);
return error;
}
/**
* 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(struct bus_type *bus,
struct device *start, void *data,
int (*match)(struct device *, void *))
{
struct klist_iter i;
struct device *dev;
if (!bus)
return NULL;
klist_iter_init_node(&bus->klist_devices, &i,
(start ? &start->knode_bus : NULL));
while ((dev = next_device(&i)))
if (match(dev, data) && get_device(dev))
break;
klist_iter_exit(&i);
return dev;
}
static struct device_driver * next_driver(struct klist_iter * i)
{
struct klist_node * n = klist_next(i);
return n ? container_of(n, struct device_driver, knode_bus) : 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(struct bus_type * bus, struct device_driver * start,
void * data, int (*fn)(struct device_driver *, void *))
{
struct klist_iter i;
struct device_driver * drv;
int error = 0;
if (!bus)
return -EINVAL;
klist_iter_init_node(&bus->klist_drivers, &i,
start ? &start->knode_bus : NULL);
while ((drv = next_driver(&i)) && !error)
error = fn(drv, data);
klist_iter_exit(&i);
return error;
}
static int device_add_attrs(struct bus_type * bus, struct device * dev)
{
int error = 0;
int i;
if (bus->dev_attrs) {
for (i = 0; attr_name(bus->dev_attrs[i]); i++) {
error = device_create_file(dev,&bus->dev_attrs[i]);
if (error)
goto Err;
}
}
Done:
return error;
Err:
while (--i >= 0)
device_remove_file(dev,&bus->dev_attrs[i]);
goto Done;
}
static void device_remove_attrs(struct bus_type * bus, struct device * dev)
{
int i;
if (bus->dev_attrs) {
for (i = 0; attr_name(bus->dev_attrs[i]); i++)
device_remove_file(dev,&bus->dev_attrs[i]);
}
}
/**
* bus_add_device - add device to bus
* @dev: device being added
*
* - Add the device to its bus's list of devices.
* - Try to attach to driver.
* - Create link to device's physical location.
*/
int bus_add_device(struct device * dev)
{
struct bus_type * bus = get_bus(dev->bus);
int error = 0;
if (bus) {
pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
device_attach(dev);
klist_add_tail(&dev->knode_bus, &bus->klist_devices);
error = device_add_attrs(bus, dev);
if (!error) {
sysfs_create_link(&bus->devices.kobj, &dev->kobj, dev->bus_id);
sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "bus");
}
}
return error;
}
/**
* bus_remove_device - remove device from bus
* @dev: device to be removed
*
* - Remove symlink from bus's directory.
* - Delete device from bus's list.
* - Detach from its driver.
* - Drop reference taken in bus_add_device().
*/
void bus_remove_device(struct device * dev)
{
if (dev->bus) {
sysfs_remove_link(&dev->kobj, "bus");
sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
device_remove_attrs(dev->bus, dev);
klist_remove(&dev->knode_bus);
pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
device_release_driver(dev);
put_bus(dev->bus);
}
}
static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)
{
int error = 0;
int i;
if (bus->drv_attrs) {
for (i = 0; attr_name(bus->drv_attrs[i]); i++) {
error = driver_create_file(drv, &bus->drv_attrs[i]);
if (error)
goto Err;
}
}
Done:
return error;
Err:
while (--i >= 0)
driver_remove_file(drv, &bus->drv_attrs[i]);
goto Done;
}
static void driver_remove_attrs(struct bus_type * bus, struct device_driver * drv)
{
int i;
if (bus->drv_attrs) {
for (i = 0; attr_name(bus->drv_attrs[i]); i++)
driver_remove_file(drv, &bus->drv_attrs[i]);
}
}
/**
* bus_add_driver - Add a driver to the bus.
* @drv: driver.
*
*/
int bus_add_driver(struct device_driver * drv)
{
struct bus_type * bus = get_bus(drv->bus);
int error = 0;
if (bus) {
pr_debug("bus %s: add driver %s\n", bus->name, drv->name);
error = kobject_set_name(&drv->kobj, "%s", drv->name);
if (error) {
put_bus(bus);
return error;
}
drv->kobj.kset = &bus->drivers;
if ((error = kobject_register(&drv->kobj))) {
put_bus(bus);
return error;
}
driver_attach(drv);
klist_add_tail(&drv->knode_bus, &bus->klist_drivers);
module_add_driver(drv->owner, drv);
driver_add_attrs(bus, drv);
driver_create_file(drv, &driver_attr_unbind);
driver_create_file(drv, &driver_attr_bind);
}
return error;
}
/**
* bus_remove_driver - delete driver from bus's knowledge.
* @drv: driver.
*
* Detach the driver from the devices it controls, and remove
* it from its bus's list of drivers. Finally, we drop the reference
* to the bus we took in bus_add_driver().
*/
void bus_remove_driver(struct device_driver * drv)
{
if (drv->bus) {
driver_remove_file(drv, &driver_attr_bind);
driver_remove_file(drv, &driver_attr_unbind);
driver_remove_attrs(drv->bus, drv);
klist_remove(&drv->knode_bus);
pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
driver_detach(drv);
module_remove_driver(drv);
kobject_unregister(&drv->kobj);
put_bus(drv->bus);
}
}
/* Helper for bus_rescan_devices's iter */
static int bus_rescan_devices_helper(struct device *dev, void *data)
{
if (!dev->driver)
device_attach(dev);
return 0;
}
/**
* bus_rescan_devices - rescan devices on the bus for possible drivers
* @bus: the bus to scan.
*
* This function will look for devices on the bus with no driver
* attached and rescan it against existing drivers to see if it matches
* any by calling device_attach() for the unbound devices.
*/
void bus_rescan_devices(struct bus_type * bus)
{
bus_for_each_dev(bus, NULL, NULL, bus_rescan_devices_helper);
}
struct bus_type * get_bus(struct bus_type * bus)
{
return bus ? container_of(subsys_get(&bus->subsys), struct bus_type, subsys) : NULL;
}
void put_bus(struct bus_type * bus)
{
subsys_put(&bus->subsys);
}
/**
* find_bus - locate bus by name.
* @name: name of bus.
*
* Call kset_find_obj() to iterate over list of buses to
* find a bus by name. Return bus if found.
*
* Note that kset_find_obj increments bus' reference count.
*/
struct bus_type * find_bus(char * name)
{
struct kobject * k = kset_find_obj(&bus_subsys.kset, name);
return k ? to_bus(k) : NULL;
}
/**
* bus_add_attrs - Add default attributes for this bus.
* @bus: Bus that has just been registered.
*/
static int bus_add_attrs(struct bus_type * bus)
{
int error = 0;
int i;
if (bus->bus_attrs) {
for (i = 0; attr_name(bus->bus_attrs[i]); i++) {
if ((error = bus_create_file(bus,&bus->bus_attrs[i])))
goto Err;
}
}
Done:
return error;
Err:
while (--i >= 0)
bus_remove_file(bus,&bus->bus_attrs[i]);
goto Done;
}
static void bus_remove_attrs(struct bus_type * bus)
{
int i;
if (bus->bus_attrs) {
for (i = 0; attr_name(bus->bus_attrs[i]); i++)
bus_remove_file(bus,&bus->bus_attrs[i]);
}
}
static void klist_devices_get(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_bus);
get_device(dev);
}
static void klist_devices_put(struct klist_node *n)
{
struct device *dev = container_of(n, struct device, knode_bus);
put_device(dev);
}
static void klist_drivers_get(struct klist_node *n)
{
struct device_driver *drv = container_of(n, struct device_driver,
knode_bus);
get_driver(drv);
}
static void klist_drivers_put(struct klist_node *n)
{
struct device_driver *drv = container_of(n, struct device_driver,
knode_bus);
put_driver(drv);
}
/**
* bus_register - register a bus with the system.
* @bus: bus.
*
* Once we have that, we registered the bus with the kobject
* infrastructure, then register the children subsystems it has:
* the devices and drivers that belong to the bus.
*/
int bus_register(struct bus_type * bus)
{
int retval;
retval = kobject_set_name(&bus->subsys.kset.kobj, "%s", bus->name);
if (retval)
goto out;
subsys_set_kset(bus, bus_subsys);
retval = subsystem_register(&bus->subsys);
if (retval)
goto out;
kobject_set_name(&bus->devices.kobj, "devices");
bus->devices.subsys = &bus->subsys;
retval = kset_register(&bus->devices);
if (retval)
goto bus_devices_fail;
kobject_set_name(&bus->drivers.kobj, "drivers");
bus->drivers.subsys = &bus->subsys;
bus->drivers.ktype = &ktype_driver;
retval = kset_register(&bus->drivers);
if (retval)
goto bus_drivers_fail;
klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);
klist_init(&bus->klist_drivers, klist_drivers_get, klist_drivers_put);
bus_add_attrs(bus);
pr_debug("bus type '%s' registered\n", bus->name);
return 0;
bus_drivers_fail:
kset_unregister(&bus->devices);
bus_devices_fail:
subsystem_unregister(&bus->subsys);
out:
return retval;
}
/**
* bus_unregister - remove a bus from the system
* @bus: bus.
*
* Unregister the child subsystems and the bus itself.
* Finally, we call put_bus() to release the refcount
*/
void bus_unregister(struct bus_type * bus)
{
pr_debug("bus %s: unregistering\n", bus->name);
bus_remove_attrs(bus);
kset_unregister(&bus->drivers);
kset_unregister(&bus->devices);
subsystem_unregister(&bus->subsys);
}
int __init buses_init(void)
{
return subsystem_register(&bus_subsys);
}
EXPORT_SYMBOL_GPL(bus_for_each_dev);
EXPORT_SYMBOL_GPL(bus_find_device);
EXPORT_SYMBOL_GPL(bus_for_each_drv);
EXPORT_SYMBOL_GPL(bus_add_device);
EXPORT_SYMBOL_GPL(bus_remove_device);
EXPORT_SYMBOL_GPL(bus_register);
EXPORT_SYMBOL_GPL(bus_unregister);
EXPORT_SYMBOL_GPL(bus_rescan_devices);
EXPORT_SYMBOL_GPL(get_bus);
EXPORT_SYMBOL_GPL(put_bus);
EXPORT_SYMBOL_GPL(find_bus);
EXPORT_SYMBOL_GPL(bus_create_file);
EXPORT_SYMBOL_GPL(bus_remove_file);