[mirror_ubuntu-artful-kernel.git] / drivers / scsi / device_handler / scsi_dh.c

/*
 * 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)
{
	struct scsi_dh_data *d;

	if (!try_module_get(scsi_dh->module))
		return -EINVAL;

	d = scsi_dh->attach(sdev);
	if (IS_ERR(d)) {
		sdev_printk(KERN_ERR, sdev, "%s: Attach failed (%ld)\n",
			    scsi_dh->name, PTR_ERR(d));
		module_put(scsi_dh->module);
		return PTR_ERR(d);
	}

	d->scsi_dh = scsi_dh;
	d->sdev = sdev;

	spin_lock_irq(sdev->request_queue->queue_lock);
	sdev->scsi_dh_data = d;
	spin_unlock_irq(sdev->request_queue->queue_lock);
	return 0;
}

/*
 * scsi_dh_handler_detach - Detach a device handler from a device
 * @sdev - SCSI device the device handler should be detached from
 */
static void scsi_dh_handler_detach(struct scsi_device *sdev)
{
	struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;
	struct scsi_device_handler *scsi_dh = scsi_dh_data->scsi_dh;

	scsi_dh->detach(sdev);

	spin_lock_irq(sdev->request_queue->queue_lock);
	sdev->scsi_dh_data = NULL;
	spin_unlock_irq(sdev->request_queue->queue_lock);

	sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", scsi_dh->name);
	module_put(scsi_dh->module);
}

/*
 * 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);
			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);
		if (sdev->scsi_dh_data)
			scsi_dh_handler_detach(sdev);
	}
	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);

	if (sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh == scsi_dh)
		scsi_dh_handler_detach(sdev);

	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;

	if (!scsi_dh->attach || !scsi_dh->detach)
		return -EINVAL;

	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)
		return err;

	if (sdev->scsi_dh_data) {
		if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
			err = -EBUSY;
		goto out_put_device;
	}

	err = scsi_dh_handler_attach(sdev, scsi_dh);

out_put_device:
	put_device(&sdev->sdev_gendev);
	return err;
}
EXPORT_SYMBOL_GPL(scsi_dh_attach);

/*
 * 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");
Commit	Line	Data
a6a8d9f8 CS	1	/*
	2	* SCSI device handler infrastruture.
	3	*
	4	* This program is free software; you can redistribute it and/or modify it
	5	* under the terms of the GNU General Public License as published by the
	6	* Free Software Foundation; either version 2 of the License, or (at your
	7	* option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful, but
	10	* WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	12	* General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License along
	15	* with this program; if not, write to the Free Software Foundation, Inc.,
	16	* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
	17	*
	18	* Copyright IBM Corporation, 2007
	19	* Authors:
	20	* Chandra Seetharaman <sekharan@us.ibm.com>
	21	* Mike Anderson <andmike@linux.vnet.ibm.com>
	22	*/
	23
5a0e3ad6	24	#include <linux/slab.h>
acf3368f	25	#include <linux/module.h>
a6a8d9f8 CS	26	#include <scsi/scsi_dh.h>
	27	#include "../scsi_priv.h"
	28
	29	static DEFINE_SPINLOCK(list_lock);
	30	static LIST_HEAD(scsi_dh_list);
	31
	32	static struct scsi_device_handler get_device_handler(const char name)
	33	{
	34	struct scsi_device_handler tmp, found = NULL;
	35
	36	spin_lock(&list_lock);
	37	list_for_each_entry(tmp, &scsi_dh_list, list) {
765cbc6d	38	if (!strncmp(tmp->name, name, strlen(tmp->name))) {
a6a8d9f8 CS	39	found = tmp;
	40	break;
	41	}
	42	}
	43	spin_unlock(&list_lock);
	44	return found;
	45	}
	46
6c3633d0 HR	47	/*
	48	* device_handler_match_function - Match a device handler to a device
	49	* @sdev - SCSI device to be tested
	50	*
	51	* Tests @sdev against the match function of all registered device_handler.
	52	* Returns the found device handler or NULL if not found.
	53	*/
	54	static struct scsi_device_handler *
	55	device_handler_match_function(struct scsi_device *sdev)
	56	{
	57	struct scsi_device_handler tmp_dh, found_dh = NULL;
	58
	59	spin_lock(&list_lock);
	60	list_for_each_entry(tmp_dh, &scsi_dh_list, list) {
	61	if (tmp_dh->match && tmp_dh->match(sdev)) {
	62	found_dh = tmp_dh;
	63	break;
	64	}
	65	}
	66	spin_unlock(&list_lock);
	67	return found_dh;
	68	}
	69
7c32c7a2 HR	70	/*
	71	* device_handler_match - Attach a device handler to a device
	72	* @scsi_dh - The device handler to match against or NULL
	73	* @sdev - SCSI device to be tested against @scsi_dh
	74	*
	75	* Tests @sdev against the device handler @scsi_dh or against
	76	* all registered device_handler if @scsi_dh == NULL.
	77	* Returns the found device handler or NULL if not found.
	78	*/
	79	static struct scsi_device_handler *
	80	device_handler_match(struct scsi_device_handler *scsi_dh,
	81	struct scsi_device *sdev)
	82	{
6c3633d0	83	struct scsi_device_handler *found_dh;
7c32c7a2	84
6c3633d0	85	found_dh = device_handler_match_function(sdev);
7c32c7a2	86
940d7faa PJ	87	if (scsi_dh && found_dh != scsi_dh)
940d7faa PJ	88	found_dh = NULL;
7c32c7a2 HR	89
7c32c7a2 HR	90	return found_dh;
a6a8d9f8 CS	91	}
	92
	93	/*
765cbc6d HR	94	* scsi_dh_handler_attach - Attach a device handler to a device
	95	* @sdev - SCSI device the device handler should attach to
	96	* @scsi_dh - The device handler to attach
	97	*/
	98	static int scsi_dh_handler_attach(struct scsi_device *sdev,
	99	struct scsi_device_handler *scsi_dh)
	100	{
1d520328	101	struct scsi_dh_data *d;
765cbc6d	102
1f12ffa5 CH	103	if (!try_module_get(scsi_dh->module))
1f12ffa5 CH	104	return -EINVAL;
27c888f0	105
1d520328 CH	106	d = scsi_dh->attach(sdev);
	107	if (IS_ERR(d)) {
	108	sdev_printk(KERN_ERR, sdev, "%s: Attach failed (%ld)\n",
	109	scsi_dh->name, PTR_ERR(d));
1f12ffa5	110	module_put(scsi_dh->module);
1d520328	111	return PTR_ERR(d);
6c10db72	112	}
1f12ffa5	113
1d520328	114	d->scsi_dh = scsi_dh;
1d520328 CH	115	d->sdev = sdev;
	116
	117	spin_lock_irq(sdev->request_queue->queue_lock);
	118	sdev->scsi_dh_data = d;
	119	spin_unlock_irq(sdev->request_queue->queue_lock);
	120	return 0;
765cbc6d HR	121	}
765cbc6d HR	122
1bab0de0 CH	123	/*
	124	* scsi_dh_handler_detach - Detach a device handler from a device
	125	* @sdev - SCSI device the device handler should be detached from
	126	*/
	127	static void scsi_dh_handler_detach(struct scsi_device *sdev)
6c10db72	128	{
1bab0de0	129	struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;
27c888f0	130	struct scsi_device_handler *scsi_dh = scsi_dh_data->scsi_dh;
1d520328	131
28072ad5 MC	132	scsi_dh->detach(sdev);
28072ad5 MC	133
1d520328 CH	134	spin_lock_irq(sdev->request_queue->queue_lock);
	135	sdev->scsi_dh_data = NULL;
	136	spin_unlock_irq(sdev->request_queue->queue_lock);
27c888f0	137
1d520328	138	sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", scsi_dh->name);
27c888f0	139	module_put(scsi_dh->module);
6c10db72 CS	140	}
6c10db72 CS	141
4c05ae52 HR	142	/*
	143	* Functions for sysfs attribute 'dh_state'
	144	*/
	145	static ssize_t
	146	store_dh_state(struct device dev, struct device_attribute attr,
	147	const char *buf, size_t count)
	148	{
	149	struct scsi_device *sdev = to_scsi_device(dev);
	150	struct scsi_device_handler *scsi_dh;
	151	int err = -EINVAL;
	152
6bc8d2a0 HR	153	if (sdev->sdev_state == SDEV_CANCEL \|\|
	154	sdev->sdev_state == SDEV_DEL)
	155	return -ENODEV;
	156
4c05ae52 HR	157	if (!sdev->scsi_dh_data) {
	158	/*
	159	* Attach to a device handler
	160	*/
	161	if (!(scsi_dh = get_device_handler(buf)))
	162	return err;
	163	err = scsi_dh_handler_attach(sdev, scsi_dh);
	164	} else {
	165	scsi_dh = sdev->scsi_dh_data->scsi_dh;
	166	if (!strncmp(buf, "detach", 6)) {
	167	/*
	168	* Detach from a device handler
	169	*/
1bab0de0	170	scsi_dh_handler_detach(sdev);
4c05ae52 HR	171	err = 0;
	172	} else if (!strncmp(buf, "activate", 8)) {
	173	/*
	174	* Activate a device handler
	175	*/
	176	if (scsi_dh->activate)
3ae31f6a	177	err = scsi_dh->activate(sdev, NULL, NULL);
4c05ae52 HR	178	else
	179	err = 0;
	180	}
	181	}
	182
	183	return err<0?err:count;
	184	}
	185
	186	static ssize_t
	187	show_dh_state(struct device dev, struct device_attribute attr, char *buf)
	188	{
	189	struct scsi_device *sdev = to_scsi_device(dev);
	190
	191	if (!sdev->scsi_dh_data)
	192	return snprintf(buf, 20, "detached\n");
	193
	194	return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
	195	}
	196
	197	static struct device_attribute scsi_dh_state_attr =
	198	__ATTR(dh_state, S_IRUGO \| S_IWUSR, show_dh_state,
	199	store_dh_state);
	200
	201	/*
	202	* scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
	203	*/
	204	static int scsi_dh_sysfs_attr_add(struct device dev, void data)
	205	{
	206	struct scsi_device *sdev;
	207	int err;
	208
	209	if (!scsi_is_sdev_device(dev))
	210	return 0;
	211
	212	sdev = to_scsi_device(dev);
	213
	214	err = device_create_file(&sdev->sdev_gendev,
	215	&scsi_dh_state_attr);
	216
	217	return 0;
	218	}
	219
	220	/*
	221	* scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
	222	*/
	223	static int scsi_dh_sysfs_attr_remove(struct device dev, void data)
	224	{
	225	struct scsi_device *sdev;
	226
	227	if (!scsi_is_sdev_device(dev))
	228	return 0;
	229
	230	sdev = to_scsi_device(dev);
	231
	232	device_remove_file(&sdev->sdev_gendev,
	233	&scsi_dh_state_attr);
	234
	235	return 0;
	236	}
	237
765cbc6d HR	238	/*
	239	* scsi_dh_notifier - notifier chain callback
	240	*/
	241	static int scsi_dh_notifier(struct notifier_block *nb,
	242	unsigned long action, void *data)
	243	{
	244	struct device *dev = data;
	245	struct scsi_device *sdev;
	246	int err = 0;
7c32c7a2	247	struct scsi_device_handler *devinfo = NULL;
765cbc6d HR	248
	249	if (!scsi_is_sdev_device(dev))
	250	return 0;
	251
	252	sdev = to_scsi_device(dev);
a6a8d9f8	253
765cbc6d	254	if (action == BUS_NOTIFY_ADD_DEVICE) {
5917290c CS	255	err = device_create_file(dev, &scsi_dh_state_attr);
5917290c CS	256	/* don't care about err */
7c32c7a2	257	devinfo = device_handler_match(NULL, sdev);
5917290c CS	258	if (devinfo)
5917290c CS	259	err = scsi_dh_handler_attach(sdev, devinfo);
765cbc6d	260	} else if (action == BUS_NOTIFY_DEL_DEVICE) {
4c05ae52	261	device_remove_file(dev, &scsi_dh_state_attr);
1bab0de0 CH	262	if (sdev->scsi_dh_data)
1bab0de0 CH	263	scsi_dh_handler_detach(sdev);
765cbc6d	264	}
765cbc6d	265	return err;
a6a8d9f8	266	}
a6a8d9f8	267
765cbc6d HR	268	/*
	269	* scsi_dh_notifier_add - Callback for scsi_register_device_handler
	270	*/
	271	static int scsi_dh_notifier_add(struct device dev, void data)
	272	{
	273	struct scsi_device_handler *scsi_dh = data;
	274	struct scsi_device *sdev;
	275
	276	if (!scsi_is_sdev_device(dev))
	277	return 0;
	278
	279	if (!get_device(dev))
	280	return 0;
	281
	282	sdev = to_scsi_device(dev);
	283
	284	if (device_handler_match(scsi_dh, sdev))
	285	scsi_dh_handler_attach(sdev, scsi_dh);
	286
	287	put_device(dev);
	288
	289	return 0;
	290	}
	291
	292	/*
	293	* scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
	294	*/
a6a8d9f8 CS	295	static int scsi_dh_notifier_remove(struct device dev, void data)
	296	{
	297	struct scsi_device_handler *scsi_dh = data;
765cbc6d HR	298	struct scsi_device *sdev;
	299
	300	if (!scsi_is_sdev_device(dev))
	301	return 0;
	302
	303	if (!get_device(dev))
	304	return 0;
	305
	306	sdev = to_scsi_device(dev);
	307
1bab0de0 CH	308	if (sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh == scsi_dh)
1bab0de0 CH	309	scsi_dh_handler_detach(sdev);
765cbc6d HR	310
765cbc6d HR	311	put_device(dev);
a6a8d9f8	312
a6a8d9f8 CS	313	return 0;
	314	}
	315
765cbc6d HR	316	/*
	317	* scsi_register_device_handler - register a device handler personality
	318	* module.
	319	* @scsi_dh - device handler to be registered.
	320	*
	321	* Returns 0 on success, -EBUSY if handler already registered.
	322	*/
	323	int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
	324	{
940d7faa	325
765cbc6d HR	326	if (get_device_handler(scsi_dh->name))
	327	return -EBUSY;
	328
1f12ffa5 CH	329	if (!scsi_dh->attach \|\| !scsi_dh->detach)
	330	return -EINVAL;
	331
765cbc6d HR	332	spin_lock(&list_lock);
	333	list_add(&scsi_dh->list, &scsi_dh_list);
	334	spin_unlock(&list_lock);
940d7faa	335
765cbc6d HR	336	bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
	337	printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
	338
	339	return SCSI_DH_OK;
	340	}
	341	EXPORT_SYMBOL_GPL(scsi_register_device_handler);
	342
a6a8d9f8 CS	343	/*
	344	* scsi_unregister_device_handler - register a device handler personality
	345	* module.
	346	* @scsi_dh - device handler to be unregistered.
	347	*
	348	* Returns 0 on success, -ENODEV if handler not registered.
	349	*/
	350	int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
	351	{
7c32c7a2	352
765cbc6d HR	353	if (!get_device_handler(scsi_dh->name))
765cbc6d HR	354	return -ENODEV;
a6a8d9f8 CS	355
a6a8d9f8 CS	356	bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
765cbc6d HR	357	scsi_dh_notifier_remove);
765cbc6d HR	358
a6a8d9f8 CS	359	spin_lock(&list_lock);
	360	list_del(&scsi_dh->list);
	361	spin_unlock(&list_lock);
765cbc6d	362	printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
a6a8d9f8	363
765cbc6d	364	return SCSI_DH_OK;
a6a8d9f8 CS	365	}
	366	EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
	367
	368	/*
	369	* scsi_dh_activate - activate the path associated with the scsi_device
	370	* corresponding to the given request queue.
3ae31f6a CS	371	* Returns immediately without waiting for activation to be completed.
	372	* @q - Request queue that is associated with the scsi_device to be
	373	* activated.
	374	* @fn - Function to be called upon completion of the activation.
	375	* Function fn is called with data (below) and the error code.
	376	* Function fn may be called from the same calling context. So,
	377	* do not hold the lock in the caller which may be needed in fn.
	378	* @data - data passed to the function fn upon completion.
	379	*
a6a8d9f8	380	*/
3ae31f6a	381	int scsi_dh_activate(struct request_queue q, activate_complete fn, void data)
a6a8d9f8 CS	382	{
	383	int err = 0;
	384	unsigned long flags;
	385	struct scsi_device *sdev;
	386	struct scsi_device_handler *scsi_dh = NULL;
0b839357	387	struct device *dev = NULL;
a6a8d9f8 CS	388
	389	spin_lock_irqsave(q->queue_lock, flags);
	390	sdev = q->queuedata;
a18a920c MB	391	if (!sdev) {
	392	spin_unlock_irqrestore(q->queue_lock, flags);
	393	err = SCSI_DH_NOSYS;
	394	if (fn)
	395	fn(data, err);
	396	return err;
	397	}
	398
	399	if (sdev->scsi_dh_data)
a6a8d9f8	400	scsi_dh = sdev->scsi_dh_data->scsi_dh;
0b839357 MS	401	dev = get_device(&sdev->sdev_gendev);
0b839357 MS	402	if (!scsi_dh \|\| !dev \|\|
db422318 MH	403	sdev->sdev_state == SDEV_CANCEL \|\|
db422318 MH	404	sdev->sdev_state == SDEV_DEL)
a6a8d9f8	405	err = SCSI_DH_NOSYS;
db422318 MH	406	if (sdev->sdev_state == SDEV_OFFLINE)
db422318 MH	407	err = SCSI_DH_DEV_OFFLINED;
a6a8d9f8 CS	408	spin_unlock_irqrestore(q->queue_lock, flags);
a6a8d9f8 CS	409
db422318 MH	410	if (err) {
	411	if (fn)
	412	fn(data, err);
0b839357	413	goto out;
db422318	414	}
a6a8d9f8 CS	415
a6a8d9f8 CS	416	if (scsi_dh->activate)
3ae31f6a	417	err = scsi_dh->activate(sdev, fn, data);
0b839357 MS	418	out:
0b839357 MS	419	put_device(dev);
a6a8d9f8 CS	420	return err;
	421	}
	422	EXPORT_SYMBOL_GPL(scsi_dh_activate);
	423
18ee70c9 CS	424	/*
	425	* scsi_dh_set_params - set the parameters for the device as per the
	426	* string specified in params.
	427	* @q - Request queue that is associated with the scsi_device for
	428	* which the parameters to be set.
	429	* @params - parameters in the following format
	430	* "no_of_params\0param1\0param2\0param3\0...\0"
	431	* for example, string for 2 parameters with value 10 and 21
	432	* is specified as "2\010\021\0".
	433	*/
	434	int scsi_dh_set_params(struct request_queue q, const char params)
	435	{
	436	int err = -SCSI_DH_NOSYS;
	437	unsigned long flags;
	438	struct scsi_device *sdev;
	439	struct scsi_device_handler *scsi_dh = NULL;
	440
	441	spin_lock_irqsave(q->queue_lock, flags);
	442	sdev = q->queuedata;
	443	if (sdev && sdev->scsi_dh_data)
	444	scsi_dh = sdev->scsi_dh_data->scsi_dh;
	445	if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
	446	err = 0;
	447	spin_unlock_irqrestore(q->queue_lock, flags);
	448
	449	if (err)
	450	return err;
	451	err = scsi_dh->set_params(sdev, params);
	452	put_device(&sdev->sdev_gendev);
	453	return err;
	454	}
	455	EXPORT_SYMBOL_GPL(scsi_dh_set_params);
	456
a6a8d9f8 CS	457	/*
	458	* scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
	459	* the given name. FALSE(0) otherwise.
	460	* @name - name of the device handler.
	461	*/
	462	int scsi_dh_handler_exist(const char *name)
	463	{
	464	return (get_device_handler(name) != NULL);
	465	}
	466	EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
	467
ae11b1b3	468	/*
2a9ab40f	469	* scsi_dh_attach - Attach device handler
7e8a74b1 MS	470	* @q - Request queue that is associated with the scsi_device
7e8a74b1 MS	471	* the handler should be attached to
ae11b1b3 HR	472	* @name - name of the handler to attach
	473	*/
	474	int scsi_dh_attach(struct request_queue q, const char name)
	475	{
	476	unsigned long flags;
	477	struct scsi_device *sdev;
	478	struct scsi_device_handler *scsi_dh;
	479	int err = 0;
	480
	481	scsi_dh = get_device_handler(name);
	482	if (!scsi_dh)
	483	return -EINVAL;
	484
	485	spin_lock_irqsave(q->queue_lock, flags);
	486	sdev = q->queuedata;
	487	if (!sdev \|\| !get_device(&sdev->sdev_gendev))
	488	err = -ENODEV;
	489	spin_unlock_irqrestore(q->queue_lock, flags);
	490
1bab0de0 CH	491	if (err)
1bab0de0 CH	492	return err;
ae11b1b3 HR	493
ae11b1b3 HR	494	if (sdev->scsi_dh_data) {
1bab0de0 CH	495	if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
	496	err = -EBUSY;
	497	goto out_put_device;
ae11b1b3	498	}
1bab0de0 CH	499
	500	err = scsi_dh_handler_attach(sdev, scsi_dh);
	501
	502	out_put_device:
ae11b1b3	503	put_device(&sdev->sdev_gendev);
1bab0de0	504	return err;
ae11b1b3	505	}
1bab0de0	506	EXPORT_SYMBOL_GPL(scsi_dh_attach);
ae11b1b3	507
7e8a74b1 MS	508	/*
	509	* scsi_dh_attached_handler_name - Get attached device handler's name
	510	* @q - Request queue that is associated with the scsi_device
	511	* that may have a device handler attached
	512	* @gfp - the GFP mask used in the kmalloc() call when allocating memory
	513	*
	514	* Returns name of attached handler, NULL if no handler is attached.
	515	* Caller must take care to free the returned string.
	516	*/
	517	const char scsi_dh_attached_handler_name(struct request_queue q, gfp_t gfp)
	518	{
	519	unsigned long flags;
	520	struct scsi_device *sdev;
	521	const char *handler_name = NULL;
	522
	523	spin_lock_irqsave(q->queue_lock, flags);
	524	sdev = q->queuedata;
	525	if (!sdev \|\| !get_device(&sdev->sdev_gendev))
	526	sdev = NULL;
	527	spin_unlock_irqrestore(q->queue_lock, flags);
	528
	529	if (!sdev)
	530	return NULL;
	531
	532	if (sdev->scsi_dh_data)
	533	handler_name = kstrdup(sdev->scsi_dh_data->scsi_dh->name, gfp);
	534
	535	put_device(&sdev->sdev_gendev);
	536	return handler_name;
	537	}
	538	EXPORT_SYMBOL_GPL(scsi_dh_attached_handler_name);
	539
765cbc6d HR	540	static struct notifier_block scsi_dh_nb = {
	541	.notifier_call = scsi_dh_notifier
	542	};
	543
	544	static int __init scsi_dh_init(void)
	545	{
	546	int r;
	547
	548	r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
	549
4c05ae52 HR	550	if (!r)
	551	bus_for_each_dev(&scsi_bus_type, NULL, NULL,
	552	scsi_dh_sysfs_attr_add);
	553
765cbc6d HR	554	return r;
	555	}
	556
	557	static void __exit scsi_dh_exit(void)
	558	{
4c05ae52 HR	559	bus_for_each_dev(&scsi_bus_type, NULL, NULL,
4c05ae52 HR	560	scsi_dh_sysfs_attr_remove);
765cbc6d HR	561	bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
	562	}
	563
	564	module_init(scsi_dh_init);
	565	module_exit(scsi_dh_exit);
	566
a6a8d9f8 CS	567	MODULE_DESCRIPTION("SCSI device handler");
	568	MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
	569	MODULE_LICENSE("GPL");