/*
* SCSI device handler infrastruture.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright IBM Corporation, 2007
* Authors:
* Chandra Seetharaman <sekharan@us.ibm.com>
* Mike Anderson <andmike@linux.vnet.ibm.com>
*/
#include <linux/slab.h>
#include <linux/module.h>
#include <scsi/scsi_dh.h>
#include "../scsi_priv.h"
static DEFINE_SPINLOCK(list_lock);
static LIST_HEAD(scsi_dh_list);
static struct scsi_device_handler *get_device_handler(const char *name)
{
struct scsi_device_handler *tmp, *found = NULL;
spin_lock(&list_lock);
list_for_each_entry(tmp, &scsi_dh_list, list) {
if (!strncmp(tmp->name, name, strlen(tmp->name))) {
found = tmp;
break;
}
}
spin_unlock(&list_lock);
return found;
}
/*
* device_handler_match_function - Match a device handler to a device
* @sdev - SCSI device to be tested
*
* Tests @sdev against the match function of all registered device_handler.
* Returns the found device handler or NULL if not found.
*/
static struct scsi_device_handler *
device_handler_match_function(struct scsi_device *sdev)
{
struct scsi_device_handler *tmp_dh, *found_dh = NULL;
spin_lock(&list_lock);
list_for_each_entry(tmp_dh, &scsi_dh_list, list) {
if (tmp_dh->match && tmp_dh->match(sdev)) {
found_dh = tmp_dh;
break;
}
}
spin_unlock(&list_lock);
return found_dh;
}
/*
* device_handler_match - Attach a device handler to a device
* @scsi_dh - The device handler to match against or NULL
* @sdev - SCSI device to be tested against @scsi_dh
*
* Tests @sdev against the device handler @scsi_dh or against
* all registered device_handler if @scsi_dh == NULL.
* Returns the found device handler or NULL if not found.
*/
static struct scsi_device_handler *
device_handler_match(struct scsi_device_handler *scsi_dh,
struct scsi_device *sdev)
{
struct scsi_device_handler *found_dh;
found_dh = device_handler_match_function(sdev);
if (scsi_dh && found_dh != scsi_dh)
found_dh = NULL;
return found_dh;
}
/*
* scsi_dh_handler_attach - Attach a device handler to a device
* @sdev - SCSI device the device handler should attach to
* @scsi_dh - The device handler to attach
*/
static int scsi_dh_handler_attach(struct scsi_device *sdev,
struct scsi_device_handler *scsi_dh)
{
int err = 0;
if (sdev->scsi_dh_data) {
if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
err = -EBUSY;
else
kref_get(&sdev->scsi_dh_data->kref);
} else if (scsi_dh->attach) {
err = scsi_dh->attach(sdev);
if (!err) {
kref_init(&sdev->scsi_dh_data->kref);
sdev->scsi_dh_data->sdev = sdev;
}
}
return err;
}
static void __detach_handler (struct kref *kref)
{
struct scsi_dh_data *scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev);
}
/*
* scsi_dh_handler_detach - Detach a device handler from a device
* @sdev - SCSI device the device handler should be detached from
* @scsi_dh - Device handler to be detached
*
* Detach from a device handler. If a device handler is specified,
* only detach if the currently attached handler matches @scsi_dh.
*/
static void scsi_dh_handler_detach(struct scsi_device *sdev,
struct scsi_device_handler *scsi_dh)
{
if (!sdev->scsi_dh_data)
return;
if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
return;
if (!scsi_dh)
scsi_dh = sdev->scsi_dh_data->scsi_dh;
if (scsi_dh && scsi_dh->detach)
kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
}
/*
* Functions for sysfs attribute 'dh_state'
*/
static ssize_t
store_dh_state(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct scsi_device *sdev = to_scsi_device(dev);
struct scsi_device_handler *scsi_dh;
int err = -EINVAL;
if (sdev->sdev_state == SDEV_CANCEL ||
sdev->sdev_state == SDEV_DEL)
return -ENODEV;
if (!sdev->scsi_dh_data) {
/*
* Attach to a device handler
*/
if (!(scsi_dh = get_device_handler(buf)))
return err;
err = scsi_dh_handler_attach(sdev, scsi_dh);
} else {
scsi_dh = sdev->scsi_dh_data->scsi_dh;
if (!strncmp(buf, "detach", 6)) {
/*
* Detach from a device handler
*/
scsi_dh_handler_detach(sdev, scsi_dh);
err = 0;
} else if (!strncmp(buf, "activate", 8)) {
/*
* Activate a device handler
*/
if (scsi_dh->activate)
err = scsi_dh->activate(sdev, NULL, NULL);
else
err = 0;
}
}
return err<0?err:count;
}
static ssize_t
show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
{
struct scsi_device *sdev = to_scsi_device(dev);
if (!sdev->scsi_dh_data)
return snprintf(buf, 20, "detached\n");
return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
}
static struct device_attribute scsi_dh_state_attr =
__ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
store_dh_state);
/*
* scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
*/
static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
{
struct scsi_device *sdev;
int err;
if (!scsi_is_sdev_device(dev))
return 0;
sdev = to_scsi_device(dev);
err = device_create_file(&sdev->sdev_gendev,
&scsi_dh_state_attr);
return 0;
}
/*
* scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
*/
static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
{
struct scsi_device *sdev;
if (!scsi_is_sdev_device(dev))
return 0;
sdev = to_scsi_device(dev);
device_remove_file(&sdev->sdev_gendev,
&scsi_dh_state_attr);
return 0;
}
/*
* scsi_dh_notifier - notifier chain callback
*/
static int scsi_dh_notifier(struct notifier_block *nb,
unsigned long action, void *data)
{
struct device *dev = data;
struct scsi_device *sdev;
int err = 0;
struct scsi_device_handler *devinfo = NULL;
if (!scsi_is_sdev_device(dev))
return 0;
sdev = to_scsi_device(dev);
if (action == BUS_NOTIFY_ADD_DEVICE) {
err = device_create_file(dev, &scsi_dh_state_attr);
/* don't care about err */
devinfo = device_handler_match(NULL, sdev);
if (devinfo)
err = scsi_dh_handler_attach(sdev, devinfo);
} else if (action == BUS_NOTIFY_DEL_DEVICE) {
device_remove_file(dev, &scsi_dh_state_attr);
scsi_dh_handler_detach(sdev, NULL);
}
return err;
}
/*
* scsi_dh_notifier_add - Callback for scsi_register_device_handler
*/
static int scsi_dh_notifier_add(struct device *dev, void *data)
{
struct scsi_device_handler *scsi_dh = data;
struct scsi_device *sdev;
if (!scsi_is_sdev_device(dev))
return 0;
if (!get_device(dev))
return 0;
sdev = to_scsi_device(dev);
if (device_handler_match(scsi_dh, sdev))
scsi_dh_handler_attach(sdev, scsi_dh);
put_device(dev);
return 0;
}
/*
* scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
*/
static int scsi_dh_notifier_remove(struct device *dev, void *data)
{
struct scsi_device_handler *scsi_dh = data;
struct scsi_device *sdev;
if (!scsi_is_sdev_device(dev))
return 0;
if (!get_device(dev))
return 0;
sdev = to_scsi_device(dev);
scsi_dh_handler_detach(sdev, scsi_dh);
put_device(dev);
return 0;
}
/*
* scsi_register_device_handler - register a device handler personality
* module.
* @scsi_dh - device handler to be registered.
*
* Returns 0 on success, -EBUSY if handler already registered.
*/
int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
{
if (get_device_handler(scsi_dh->name))
return -EBUSY;
spin_lock(&list_lock);
list_add(&scsi_dh->list, &scsi_dh_list);
spin_unlock(&list_lock);
bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
return SCSI_DH_OK;
}
EXPORT_SYMBOL_GPL(scsi_register_device_handler);
/*
* scsi_unregister_device_handler - register a device handler personality
* module.
* @scsi_dh - device handler to be unregistered.
*
* Returns 0 on success, -ENODEV if handler not registered.
*/
int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
{
if (!get_device_handler(scsi_dh->name))
return -ENODEV;
bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
scsi_dh_notifier_remove);
spin_lock(&list_lock);
list_del(&scsi_dh->list);
spin_unlock(&list_lock);
printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
return SCSI_DH_OK;
}
EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
/*
* scsi_dh_activate - activate the path associated with the scsi_device
* corresponding to the given request queue.
* Returns immediately without waiting for activation to be completed.
* @q - Request queue that is associated with the scsi_device to be
* activated.
* @fn - Function to be called upon completion of the activation.
* Function fn is called with data (below) and the error code.
* Function fn may be called from the same calling context. So,
* do not hold the lock in the caller which may be needed in fn.
* @data - data passed to the function fn upon completion.
*
*/
int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
{
int err = 0;
unsigned long flags;
struct scsi_device *sdev;
struct scsi_device_handler *scsi_dh = NULL;
struct device *dev = NULL;
spin_lock_irqsave(q->queue_lock, flags);
sdev = q->queuedata;
if (!sdev) {
spin_unlock_irqrestore(q->queue_lock, flags);
err = SCSI_DH_NOSYS;
if (fn)
fn(data, err);
return err;
}
if (sdev->scsi_dh_data)
scsi_dh = sdev->scsi_dh_data->scsi_dh;
dev = get_device(&sdev->sdev_gendev);
if (!scsi_dh || !dev ||
sdev->sdev_state == SDEV_CANCEL ||
sdev->sdev_state == SDEV_DEL)
err = SCSI_DH_NOSYS;
if (sdev->sdev_state == SDEV_OFFLINE)
err = SCSI_DH_DEV_OFFLINED;
spin_unlock_irqrestore(q->queue_lock, flags);
if (err) {
if (fn)
fn(data, err);
goto out;
}
if (scsi_dh->activate)
err = scsi_dh->activate(sdev, fn, data);
out:
put_device(dev);
return err;
}
EXPORT_SYMBOL_GPL(scsi_dh_activate);
/*
* scsi_dh_set_params - set the parameters for the device as per the
* string specified in params.
* @q - Request queue that is associated with the scsi_device for
* which the parameters to be set.
* @params - parameters in the following format
* "no_of_params\0param1\0param2\0param3\0...\0"
* for example, string for 2 parameters with value 10 and 21
* is specified as "2\010\021\0".
*/
int scsi_dh_set_params(struct request_queue *q, const char *params)
{
int err = -SCSI_DH_NOSYS;
unsigned long flags;
struct scsi_device *sdev;
struct scsi_device_handler *scsi_dh = NULL;
spin_lock_irqsave(q->queue_lock, flags);
sdev = q->queuedata;
if (sdev && sdev->scsi_dh_data)
scsi_dh = sdev->scsi_dh_data->scsi_dh;
if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
err = 0;
spin_unlock_irqrestore(q->queue_lock, flags);
if (err)
return err;
err = scsi_dh->set_params(sdev, params);
put_device(&sdev->sdev_gendev);
return err;
}
EXPORT_SYMBOL_GPL(scsi_dh_set_params);
/*
* scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
* the given name. FALSE(0) otherwise.
* @name - name of the device handler.
*/
int scsi_dh_handler_exist(const char *name)
{
return (get_device_handler(name) != NULL);
}
EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
/*
* scsi_dh_attach - Attach device handler
* @q - Request queue that is associated with the scsi_device
* the handler should be attached to
* @name - name of the handler to attach
*/
int scsi_dh_attach(struct request_queue *q, const char *name)
{
unsigned long flags;
struct scsi_device *sdev;
struct scsi_device_handler *scsi_dh;
int err = 0;
scsi_dh = get_device_handler(name);
if (!scsi_dh)
return -EINVAL;
spin_lock_irqsave(q->queue_lock, flags);
sdev = q->queuedata;
if (!sdev || !get_device(&sdev->sdev_gendev))
err = -ENODEV;
spin_unlock_irqrestore(q->queue_lock, flags);
if (!err) {
err = scsi_dh_handler_attach(sdev, scsi_dh);
put_device(&sdev->sdev_gendev);
}
return err;
}
EXPORT_SYMBOL_GPL(scsi_dh_attach);
/*
* scsi_dh_detach - Detach device handler
* @q - Request queue that is associated with the scsi_device
* the handler should be detached from
*
* This function will detach the device handler only
* if the sdev is not part of the internal list, ie
* if it has been attached manually.
*/
void scsi_dh_detach(struct request_queue *q)
{
unsigned long flags;
struct scsi_device *sdev;
struct scsi_device_handler *scsi_dh = NULL;
spin_lock_irqsave(q->queue_lock, flags);
sdev = q->queuedata;
if (!sdev || !get_device(&sdev->sdev_gendev))
sdev = NULL;
spin_unlock_irqrestore(q->queue_lock, flags);
if (!sdev)
return;
if (sdev->scsi_dh_data) {
scsi_dh = sdev->scsi_dh_data->scsi_dh;
scsi_dh_handler_detach(sdev, scsi_dh);
}
put_device(&sdev->sdev_gendev);
}
EXPORT_SYMBOL_GPL(scsi_dh_detach);
/*
* scsi_dh_attached_handler_name - Get attached device handler's name
* @q - Request queue that is associated with the scsi_device
* that may have a device handler attached
* @gfp - the GFP mask used in the kmalloc() call when allocating memory
*
* Returns name of attached handler, NULL if no handler is attached.
* Caller must take care to free the returned string.
*/
const char *scsi_dh_attached_handler_name(struct request_queue *q, gfp_t gfp)
{
unsigned long flags;
struct scsi_device *sdev;
const char *handler_name = NULL;
spin_lock_irqsave(q->queue_lock, flags);
sdev = q->queuedata;
if (!sdev || !get_device(&sdev->sdev_gendev))
sdev = NULL;
spin_unlock_irqrestore(q->queue_lock, flags);
if (!sdev)
return NULL;
if (sdev->scsi_dh_data)
handler_name = kstrdup(sdev->scsi_dh_data->scsi_dh->name, gfp);
put_device(&sdev->sdev_gendev);
return handler_name;
}
EXPORT_SYMBOL_GPL(scsi_dh_attached_handler_name);
static struct notifier_block scsi_dh_nb = {
.notifier_call = scsi_dh_notifier
};
static int __init scsi_dh_init(void)
{
int r;
r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
if (!r)
bus_for_each_dev(&scsi_bus_type, NULL, NULL,
scsi_dh_sysfs_attr_add);
return r;
}
static void __exit scsi_dh_exit(void)
{
bus_for_each_dev(&scsi_bus_type, NULL, NULL,
scsi_dh_sysfs_attr_remove);
bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
}
module_init(scsi_dh_init);
module_exit(scsi_dh_exit);
MODULE_DESCRIPTION("SCSI device handler");
MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
MODULE_LICENSE("GPL");
