android_kernel_motorola_sm6225/drivers/s390/cio/ccwgroup.c
Cornelia Huck 1a908c735a [S390] cio: Fix ungroup vs. machine check race in ccwgroup.
There are two ways for a ccwgroup device to be unregistered:
Via the ungroup attribute, or when on of the slave devices is killed
by a machine check. As we have to unregister the ccwgroup device
via a callback, we'll now have to check whether it hasn't been
already unregistered because of a machine check.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-01-26 14:11:04 +01:00

512 lines
12 KiB
C

/*
* drivers/s390/cio/ccwgroup.c
* bus driver for ccwgroup
*
* Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
* IBM Corporation
* Author(s): Arnd Bergmann (arndb@de.ibm.com)
* Cornelia Huck (cornelia.huck@de.ibm.com)
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/ctype.h>
#include <linux/dcache.h>
#include <asm/semaphore.h>
#include <asm/ccwdev.h>
#include <asm/ccwgroup.h>
/* In Linux 2.4, we had a channel device layer called "chandev"
* that did all sorts of obscure stuff for networking devices.
* This is another driver that serves as a replacement for just
* one of its functions, namely the translation of single subchannels
* to devices that use multiple subchannels.
*/
/* a device matches a driver if all its slave devices match the same
* entry of the driver */
static int
ccwgroup_bus_match (struct device * dev, struct device_driver * drv)
{
struct ccwgroup_device *gdev;
struct ccwgroup_driver *gdrv;
gdev = to_ccwgroupdev(dev);
gdrv = to_ccwgroupdrv(drv);
if (gdev->creator_id == gdrv->driver_id)
return 1;
return 0;
}
static int
ccwgroup_uevent (struct device *dev, struct kobj_uevent_env *env)
{
/* TODO */
return 0;
}
static struct bus_type ccwgroup_bus_type;
static void
__ccwgroup_remove_symlinks(struct ccwgroup_device *gdev)
{
int i;
char str[8];
for (i = 0; i < gdev->count; i++) {
sprintf(str, "cdev%d", i);
sysfs_remove_link(&gdev->dev.kobj, str);
sysfs_remove_link(&gdev->cdev[i]->dev.kobj, "group_device");
}
}
/*
* Provide an 'ungroup' attribute so the user can remove group devices no
* longer needed or accidentially created. Saves memory :)
*/
static void ccwgroup_ungroup_callback(struct device *dev)
{
struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
mutex_lock(&gdev->reg_mutex);
if (device_is_registered(&gdev->dev)) {
__ccwgroup_remove_symlinks(gdev);
device_unregister(dev);
}
mutex_unlock(&gdev->reg_mutex);
}
static ssize_t
ccwgroup_ungroup_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
struct ccwgroup_device *gdev;
int rc;
gdev = to_ccwgroupdev(dev);
if (gdev->state != CCWGROUP_OFFLINE)
return -EINVAL;
/* Note that we cannot unregister the device from one of its
* attribute methods, so we have to use this roundabout approach.
*/
rc = device_schedule_callback(dev, ccwgroup_ungroup_callback);
if (rc)
count = rc;
return count;
}
static DEVICE_ATTR(ungroup, 0200, NULL, ccwgroup_ungroup_store);
static void
ccwgroup_release (struct device *dev)
{
struct ccwgroup_device *gdev;
int i;
gdev = to_ccwgroupdev(dev);
for (i = 0; i < gdev->count; i++) {
dev_set_drvdata(&gdev->cdev[i]->dev, NULL);
put_device(&gdev->cdev[i]->dev);
}
kfree(gdev);
}
static int
__ccwgroup_create_symlinks(struct ccwgroup_device *gdev)
{
char str[8];
int i, rc;
for (i = 0; i < gdev->count; i++) {
rc = sysfs_create_link(&gdev->cdev[i]->dev.kobj, &gdev->dev.kobj,
"group_device");
if (rc) {
for (--i; i >= 0; i--)
sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
"group_device");
return rc;
}
}
for (i = 0; i < gdev->count; i++) {
sprintf(str, "cdev%d", i);
rc = sysfs_create_link(&gdev->dev.kobj, &gdev->cdev[i]->dev.kobj,
str);
if (rc) {
for (--i; i >= 0; i--) {
sprintf(str, "cdev%d", i);
sysfs_remove_link(&gdev->dev.kobj, str);
}
for (i = 0; i < gdev->count; i++)
sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
"group_device");
return rc;
}
}
return 0;
}
/**
* ccwgroup_create() - create and register a ccw group device
* @root: parent device for the new device
* @creator_id: identifier of creating driver
* @cdrv: ccw driver of slave devices
* @argc: number of slave devices
* @argv: bus ids of slave devices
*
* Create and register a new ccw group device as a child of @root. Slave
* devices are obtained from the list of bus ids given in @argv[] and must all
* belong to @cdrv.
* Returns:
* %0 on success and an error code on failure.
* Context:
* non-atomic
*/
int ccwgroup_create(struct device *root, unsigned int creator_id,
struct ccw_driver *cdrv, int argc, char *argv[])
{
struct ccwgroup_device *gdev;
int i;
int rc;
if (argc > 256) /* disallow dumb users */
return -EINVAL;
gdev = kzalloc(sizeof(*gdev) + argc*sizeof(gdev->cdev[0]), GFP_KERNEL);
if (!gdev)
return -ENOMEM;
atomic_set(&gdev->onoff, 0);
mutex_init(&gdev->reg_mutex);
mutex_lock(&gdev->reg_mutex);
for (i = 0; i < argc; i++) {
gdev->cdev[i] = get_ccwdev_by_busid(cdrv, argv[i]);
/* all devices have to be of the same type in
* order to be grouped */
if (!gdev->cdev[i]
|| gdev->cdev[i]->id.driver_info !=
gdev->cdev[0]->id.driver_info) {
rc = -EINVAL;
goto error;
}
/* Don't allow a device to belong to more than one group. */
if (dev_get_drvdata(&gdev->cdev[i]->dev)) {
rc = -EINVAL;
goto error;
}
dev_set_drvdata(&gdev->cdev[i]->dev, gdev);
}
gdev->creator_id = creator_id;
gdev->count = argc;
gdev->dev.bus = &ccwgroup_bus_type;
gdev->dev.parent = root;
gdev->dev.release = ccwgroup_release;
snprintf (gdev->dev.bus_id, BUS_ID_SIZE, "%s",
gdev->cdev[0]->dev.bus_id);
rc = device_register(&gdev->dev);
if (rc)
goto error;
get_device(&gdev->dev);
rc = device_create_file(&gdev->dev, &dev_attr_ungroup);
if (rc) {
device_unregister(&gdev->dev);
goto error;
}
rc = __ccwgroup_create_symlinks(gdev);
if (!rc) {
mutex_unlock(&gdev->reg_mutex);
put_device(&gdev->dev);
return 0;
}
device_remove_file(&gdev->dev, &dev_attr_ungroup);
device_unregister(&gdev->dev);
error:
for (i = 0; i < argc; i++)
if (gdev->cdev[i]) {
if (dev_get_drvdata(&gdev->cdev[i]->dev) == gdev)
dev_set_drvdata(&gdev->cdev[i]->dev, NULL);
put_device(&gdev->cdev[i]->dev);
}
mutex_unlock(&gdev->reg_mutex);
put_device(&gdev->dev);
return rc;
}
static int __init
init_ccwgroup (void)
{
return bus_register (&ccwgroup_bus_type);
}
static void __exit
cleanup_ccwgroup (void)
{
bus_unregister (&ccwgroup_bus_type);
}
module_init(init_ccwgroup);
module_exit(cleanup_ccwgroup);
/************************** driver stuff ******************************/
static int
ccwgroup_set_online(struct ccwgroup_device *gdev)
{
struct ccwgroup_driver *gdrv;
int ret;
if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
return -EAGAIN;
if (gdev->state == CCWGROUP_ONLINE) {
ret = 0;
goto out;
}
if (!gdev->dev.driver) {
ret = -EINVAL;
goto out;
}
gdrv = to_ccwgroupdrv (gdev->dev.driver);
if ((ret = gdrv->set_online ? gdrv->set_online(gdev) : 0))
goto out;
gdev->state = CCWGROUP_ONLINE;
out:
atomic_set(&gdev->onoff, 0);
return ret;
}
static int
ccwgroup_set_offline(struct ccwgroup_device *gdev)
{
struct ccwgroup_driver *gdrv;
int ret;
if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
return -EAGAIN;
if (gdev->state == CCWGROUP_OFFLINE) {
ret = 0;
goto out;
}
if (!gdev->dev.driver) {
ret = -EINVAL;
goto out;
}
gdrv = to_ccwgroupdrv (gdev->dev.driver);
if ((ret = gdrv->set_offline ? gdrv->set_offline(gdev) : 0))
goto out;
gdev->state = CCWGROUP_OFFLINE;
out:
atomic_set(&gdev->onoff, 0);
return ret;
}
static ssize_t
ccwgroup_online_store (struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
struct ccwgroup_device *gdev;
struct ccwgroup_driver *gdrv;
unsigned int value;
int ret;
gdev = to_ccwgroupdev(dev);
if (!dev->driver)
return count;
gdrv = to_ccwgroupdrv (gdev->dev.driver);
if (!try_module_get(gdrv->owner))
return -EINVAL;
value = simple_strtoul(buf, NULL, 0);
ret = count;
if (value == 1)
ccwgroup_set_online(gdev);
else if (value == 0)
ccwgroup_set_offline(gdev);
else
ret = -EINVAL;
module_put(gdrv->owner);
return ret;
}
static ssize_t
ccwgroup_online_show (struct device *dev, struct device_attribute *attr, char *buf)
{
int online;
online = (to_ccwgroupdev(dev)->state == CCWGROUP_ONLINE);
return sprintf(buf, online ? "1\n" : "0\n");
}
static DEVICE_ATTR(online, 0644, ccwgroup_online_show, ccwgroup_online_store);
static int
ccwgroup_probe (struct device *dev)
{
struct ccwgroup_device *gdev;
struct ccwgroup_driver *gdrv;
int ret;
gdev = to_ccwgroupdev(dev);
gdrv = to_ccwgroupdrv(dev->driver);
if ((ret = device_create_file(dev, &dev_attr_online)))
return ret;
ret = gdrv->probe ? gdrv->probe(gdev) : -ENODEV;
if (ret)
device_remove_file(dev, &dev_attr_online);
return ret;
}
static int
ccwgroup_remove (struct device *dev)
{
struct ccwgroup_device *gdev;
struct ccwgroup_driver *gdrv;
gdev = to_ccwgroupdev(dev);
gdrv = to_ccwgroupdrv(dev->driver);
device_remove_file(dev, &dev_attr_online);
if (gdrv && gdrv->remove)
gdrv->remove(gdev);
return 0;
}
static struct bus_type ccwgroup_bus_type = {
.name = "ccwgroup",
.match = ccwgroup_bus_match,
.uevent = ccwgroup_uevent,
.probe = ccwgroup_probe,
.remove = ccwgroup_remove,
};
/**
* ccwgroup_driver_register() - register a ccw group driver
* @cdriver: driver to be registered
*
* This function is mainly a wrapper around driver_register().
*/
int ccwgroup_driver_register(struct ccwgroup_driver *cdriver)
{
/* register our new driver with the core */
cdriver->driver.bus = &ccwgroup_bus_type;
cdriver->driver.name = cdriver->name;
cdriver->driver.owner = cdriver->owner;
return driver_register(&cdriver->driver);
}
static int
__ccwgroup_match_all(struct device *dev, void *data)
{
return 1;
}
/**
* ccwgroup_driver_unregister() - deregister a ccw group driver
* @cdriver: driver to be deregistered
*
* This function is mainly a wrapper around driver_unregister().
*/
void ccwgroup_driver_unregister(struct ccwgroup_driver *cdriver)
{
struct device *dev;
/* We don't want ccwgroup devices to live longer than their driver. */
get_driver(&cdriver->driver);
while ((dev = driver_find_device(&cdriver->driver, NULL, NULL,
__ccwgroup_match_all))) {
struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
mutex_lock(&gdev->reg_mutex);
__ccwgroup_remove_symlinks(gdev);
device_unregister(dev);
mutex_unlock(&gdev->reg_mutex);
put_device(dev);
}
put_driver(&cdriver->driver);
driver_unregister(&cdriver->driver);
}
/**
* ccwgroup_probe_ccwdev() - probe function for slave devices
* @cdev: ccw device to be probed
*
* This is a dummy probe function for ccw devices that are slave devices in
* a ccw group device.
* Returns:
* always %0
*/
int ccwgroup_probe_ccwdev(struct ccw_device *cdev)
{
return 0;
}
static struct ccwgroup_device *
__ccwgroup_get_gdev_by_cdev(struct ccw_device *cdev)
{
struct ccwgroup_device *gdev;
gdev = dev_get_drvdata(&cdev->dev);
if (gdev) {
if (get_device(&gdev->dev)) {
mutex_lock(&gdev->reg_mutex);
if (device_is_registered(&gdev->dev))
return gdev;
mutex_unlock(&gdev->reg_mutex);
put_device(&gdev->dev);
}
return NULL;
}
return NULL;
}
/**
* ccwgroup_remove_ccwdev() - remove function for slave devices
* @cdev: ccw device to be removed
*
* This is a remove function for ccw devices that are slave devices in a ccw
* group device. It sets the ccw device offline and also deregisters the
* embedding ccw group device.
*/
void ccwgroup_remove_ccwdev(struct ccw_device *cdev)
{
struct ccwgroup_device *gdev;
/* Ignore offlining errors, device is gone anyway. */
ccw_device_set_offline(cdev);
/* If one of its devices is gone, the whole group is done for. */
gdev = __ccwgroup_get_gdev_by_cdev(cdev);
if (gdev) {
__ccwgroup_remove_symlinks(gdev);
device_unregister(&gdev->dev);
mutex_unlock(&gdev->reg_mutex);
put_device(&gdev->dev);
}
}
MODULE_LICENSE("GPL");
EXPORT_SYMBOL(ccwgroup_driver_register);
EXPORT_SYMBOL(ccwgroup_driver_unregister);
EXPORT_SYMBOL(ccwgroup_create);
EXPORT_SYMBOL(ccwgroup_probe_ccwdev);
EXPORT_SYMBOL(ccwgroup_remove_ccwdev);