[linux-block.git] / drivers / scsi / scsi_dh.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * SCSI device handler infrastructure.
 *
 * 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);

struct scsi_dh_blist {
	const char *vendor;
	const char *model;
	const char *driver;
};

static const struct scsi_dh_blist scsi_dh_blist[] = {
	{"DGC", "RAID",			"emc" },
	{"DGC", "DISK",			"emc" },
	{"DGC", "VRAID",		"emc" },

	{"COMPAQ", "MSA1000 VOLUME",	"hp_sw" },
	{"COMPAQ", "HSV110",		"hp_sw" },
	{"HP", "HSV100",		"hp_sw"},
	{"DEC", "HSG80",		"hp_sw"},

	{"IBM", "1722",			"rdac", },
	{"IBM", "1724",			"rdac", },
	{"IBM", "1726",			"rdac", },
	{"IBM", "1742",			"rdac", },
	{"IBM", "1745",			"rdac", },
	{"IBM", "1746",			"rdac", },
	{"IBM", "1813",			"rdac", },
	{"IBM", "1814",			"rdac", },
	{"IBM", "1815",			"rdac", },
	{"IBM", "1818",			"rdac", },
	{"IBM", "3526",			"rdac", },
	{"IBM", "3542",			"rdac", },
	{"IBM", "3552",			"rdac", },
	{"SGI", "TP9300",		"rdac", },
	{"SGI", "TP9400",		"rdac", },
	{"SGI", "TP9500",		"rdac", },
	{"SGI", "TP9700",		"rdac", },
	{"SGI", "IS",			"rdac", },
	{"STK", "OPENstorage",		"rdac", },
	{"STK", "FLEXLINE 380",		"rdac", },
	{"STK", "BladeCtlr",		"rdac", },
	{"SUN", "CSM",			"rdac", },
	{"SUN", "LCSM100",		"rdac", },
	{"SUN", "STK6580_6780",		"rdac", },
	{"SUN", "SUN_6180",		"rdac", },
	{"SUN", "ArrayStorage",		"rdac", },
	{"DELL", "MD3",			"rdac", },
	{"NETAPP", "INF-01-00",		"rdac", },
	{"LSI", "INF-01-00",		"rdac", },
	{"ENGENIO", "INF-01-00",	"rdac", },
	{"LENOVO", "DE_Series",		"rdac", },
	{"FUJITSU", "ETERNUS_AHB",	"rdac", },
	{NULL, NULL,			NULL },
};

static const char *
scsi_dh_find_driver(struct scsi_device *sdev)
{
	const struct scsi_dh_blist *b;

	if (scsi_device_tpgs(sdev))
		return "alua";

	for (b = scsi_dh_blist; b->vendor; b++) {
		if (!strncmp(sdev->vendor, b->vendor, strlen(b->vendor)) &&
		    !strncmp(sdev->model, b->model, strlen(b->model))) {
			return b->driver;
		}
	}
	return NULL;
}


static struct scsi_device_handler *__scsi_dh_lookup(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;
}

static struct scsi_device_handler *scsi_dh_lookup(const char *name)
{
	struct scsi_device_handler *dh;

	if (!name || strlen(name) == 0)
		return NULL;

	dh = __scsi_dh_lookup(name);
	if (!dh) {
		request_module("scsi_dh_%s", name);
		dh = __scsi_dh_lookup(name);
	}

	return 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 error, ret = 0;

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

	error = scsi_dh->attach(sdev);
	if (error != SCSI_DH_OK) {
		switch (error) {
		case SCSI_DH_NOMEM:
			ret = -ENOMEM;
			break;
		case SCSI_DH_RES_TEMP_UNAVAIL:
			ret = -EAGAIN;
			break;
		case SCSI_DH_DEV_UNSUPP:
		case SCSI_DH_NOSYS:
			ret = -ENODEV;
			break;
		default:
			ret = -EINVAL;
			break;
		}
		if (ret != -ENODEV)
			sdev_printk(KERN_ERR, sdev, "%s: Attach failed (%d)\n",
				    scsi_dh->name, error);
		module_put(scsi_dh->module);
	} else
		sdev->handler = scsi_dh;

	return ret;
}

/*
 * 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)
{
	sdev->handler->detach(sdev);
	sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", sdev->handler->name);
	module_put(sdev->handler->module);
}

void scsi_dh_add_device(struct scsi_device *sdev)
{
	struct scsi_device_handler *devinfo = NULL;
	const char *drv;

	drv = scsi_dh_find_driver(sdev);
	if (drv)
		devinfo = __scsi_dh_lookup(drv);
	/*
	 * device_handler is optional, so ignore errors
	 * from scsi_dh_handler_attach()
	 */
	if (devinfo)
		(void)scsi_dh_handler_attach(sdev, devinfo);
}

void scsi_dh_release_device(struct scsi_device *sdev)
{
	if (sdev->handler)
		scsi_dh_handler_detach(sdev);
}

/*
 * 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 (__scsi_dh_lookup(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);

	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 (!__scsi_dh_lookup(scsi_dh->name))
		return -ENODEV;

	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)
{
	struct scsi_device *sdev;
	int err = SCSI_DH_NOSYS;

	sdev = scsi_device_from_queue(q);
	if (!sdev) {
		if (fn)
			fn(data, err);
		return err;
	}

	if (!sdev->handler)
		goto out_fn;
	err = SCSI_DH_NOTCONN;
	if (sdev->sdev_state == SDEV_CANCEL ||
	    sdev->sdev_state == SDEV_DEL)
		goto out_fn;

	err = SCSI_DH_DEV_OFFLINED;
	if (sdev->sdev_state == SDEV_OFFLINE)
		goto out_fn;

	if (sdev->handler->activate)
		err = sdev->handler->activate(sdev, fn, data);

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

out_fn:
	if (fn)
		fn(data, err);
	goto out_put_device;
}
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)
{
	struct scsi_device *sdev;
	int err = -SCSI_DH_NOSYS;

	sdev = scsi_device_from_queue(q);
	if (!sdev)
		return err;

	if (sdev->handler && sdev->handler->set_params)
		err = sdev->handler->set_params(sdev, params);
	put_device(&sdev->sdev_gendev);
	return err;
}
EXPORT_SYMBOL_GPL(scsi_dh_set_params);

/*
 * 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)
{
	struct scsi_device *sdev;
	struct scsi_device_handler *scsi_dh;
	int err = 0;

	sdev = scsi_device_from_queue(q);
	if (!sdev)
		return -ENODEV;

	scsi_dh = scsi_dh_lookup(name);
	if (!scsi_dh) {
		err = -EINVAL;
		goto out_put_device;
	}

	if (sdev->handler) {
		if (sdev->handler != 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)
{
	struct scsi_device *sdev;
	const char *handler_name = NULL;

	sdev = scsi_device_from_queue(q);
	if (!sdev)
		return NULL;

	if (sdev->handler)
		handler_name = kstrdup(sdev->handler->name, gfp);
	put_device(&sdev->sdev_gendev);
	return handler_name;
}
EXPORT_SYMBOL_GPL(scsi_dh_attached_handler_name);
Commit	Line	Data
1a59d1b8	1	// SPDX-License-Identifier: GPL-2.0-or-later
a6a8d9f8	2	/*
ae98ddf0	3	* SCSI device handler infrastructure.
a6a8d9f8	4	*
a6a8d9f8 CS	5	* Copyright IBM Corporation, 2007
	6	* Authors:
	7	* Chandra Seetharaman <sekharan@us.ibm.com>
	8	* Mike Anderson <andmike@linux.vnet.ibm.com>
	9	*/
	10
5a0e3ad6	11	#include <linux/slab.h>
acf3368f	12	#include <linux/module.h>
a6a8d9f8	13	#include <scsi/scsi_dh.h>
daaa858b	14	#include "scsi_priv.h"
a6a8d9f8 CS	15
	16	static DEFINE_SPINLOCK(list_lock);
	17	static LIST_HEAD(scsi_dh_list);
	18
d95dbff2 CH	19	struct scsi_dh_blist {
	20	const char *vendor;
	21	const char *model;
	22	const char *driver;
	23	};
	24
	25	static const struct scsi_dh_blist scsi_dh_blist[] = {
0ba43a81 XVP	26	{"DGC", "RAID", "emc" },
	27	{"DGC", "DISK", "emc" },
	28	{"DGC", "VRAID", "emc" },
d95dbff2 CH	29
	30	{"COMPAQ", "MSA1000 VOLUME", "hp_sw" },
	31	{"COMPAQ", "HSV110", "hp_sw" },
	32	{"HP", "HSV100", "hp_sw"},
	33	{"DEC", "HSG80", "hp_sw"},
	34
	35	{"IBM", "1722", "rdac", },
	36	{"IBM", "1724", "rdac", },
	37	{"IBM", "1726", "rdac", },
	38	{"IBM", "1742", "rdac", },
	39	{"IBM", "1745", "rdac", },
	40	{"IBM", "1746", "rdac", },
	41	{"IBM", "1813", "rdac", },
	42	{"IBM", "1814", "rdac", },
	43	{"IBM", "1815", "rdac", },
	44	{"IBM", "1818", "rdac", },
	45	{"IBM", "3526", "rdac", },
4b3aec2b XVP	46	{"IBM", "3542", "rdac", },
4b3aec2b XVP	47	{"IBM", "3552", "rdac", },
37b37d26 XVP	48	{"SGI", "TP9300", "rdac", },
	49	{"SGI", "TP9400", "rdac", },
	50	{"SGI", "TP9500", "rdac", },
	51	{"SGI", "TP9700", "rdac", },
d95dbff2	52	{"SGI", "IS", "rdac", },
4b3aec2b	53	{"STK", "OPENstorage", "rdac", },
d95dbff2	54	{"STK", "FLEXLINE 380", "rdac", },
4b3aec2b	55	{"STK", "BladeCtlr", "rdac", },
d95dbff2 CH	56	{"SUN", "CSM", "rdac", },
	57	{"SUN", "LCSM100", "rdac", },
	58	{"SUN", "STK6580_6780", "rdac", },
	59	{"SUN", "SUN_6180", "rdac", },
	60	{"SUN", "ArrayStorage", "rdac", },
	61	{"DELL", "MD3", "rdac", },
	62	{"NETAPP", "INF-01-00", "rdac", },
	63	{"LSI", "INF-01-00", "rdac", },
	64	{"ENGENIO", "INF-01-00", "rdac", },
1cb1d2c6	65	{"LENOVO", "DE_Series", "rdac", },
e094fd34	66	{"FUJITSU", "ETERNUS_AHB", "rdac", },
d95dbff2 CH	67	{NULL, NULL, NULL },
	68	};
	69
	70	static const char *
	71	scsi_dh_find_driver(struct scsi_device *sdev)
	72	{
	73	const struct scsi_dh_blist *b;
	74
	75	if (scsi_device_tpgs(sdev))
	76	return "alua";
	77
	78	for (b = scsi_dh_blist; b->vendor; b++) {
	79	if (!strncmp(sdev->vendor, b->vendor, strlen(b->vendor)) &&
	80	!strncmp(sdev->model, b->model, strlen(b->model))) {
	81	return b->driver;
	82	}
	83	}
	84	return NULL;
	85	}
	86
	87
566079c8	88	static struct scsi_device_handler __scsi_dh_lookup(const char name)
a6a8d9f8 CS	89	{
	90	struct scsi_device_handler tmp, found = NULL;
	91
	92	spin_lock(&list_lock);
	93	list_for_each_entry(tmp, &scsi_dh_list, list) {
765cbc6d	94	if (!strncmp(tmp->name, name, strlen(tmp->name))) {
a6a8d9f8 CS	95	found = tmp;
	96	break;
	97	}
	98	}
	99	spin_unlock(&list_lock);
	100	return found;
	101	}
	102
566079c8 CH	103	static struct scsi_device_handler scsi_dh_lookup(const char name)
	104	{
	105	struct scsi_device_handler *dh;
	106
2ee5671e JT	107	if (!name \|\| strlen(name) == 0)
	108	return NULL;
	109
566079c8 CH	110	dh = __scsi_dh_lookup(name);
566079c8 CH	111	if (!dh) {
1378889c	112	request_module("scsi_dh_%s", name);
566079c8 CH	113	dh = __scsi_dh_lookup(name);
	114	}
	115
	116	return dh;
	117	}
	118
a6a8d9f8	119	/*
765cbc6d HR	120	* scsi_dh_handler_attach - Attach a device handler to a device
	121	* @sdev - SCSI device the device handler should attach to
	122	* @scsi_dh - The device handler to attach
	123	*/
	124	static int scsi_dh_handler_attach(struct scsi_device *sdev,
	125	struct scsi_device_handler *scsi_dh)
	126	{
2a8f7a03	127	int error, ret = 0;
765cbc6d	128
1f12ffa5 CH	129	if (!try_module_get(scsi_dh->module))
1f12ffa5 CH	130	return -EINVAL;
27c888f0	131
ee14c674	132	error = scsi_dh->attach(sdev);
2a8f7a03 HR	133	if (error != SCSI_DH_OK) {
	134	switch (error) {
	135	case SCSI_DH_NOMEM:
	136	ret = -ENOMEM;
	137	break;
	138	case SCSI_DH_RES_TEMP_UNAVAIL:
	139	ret = -EAGAIN;
	140	break;
2930f817 HR	141	case SCSI_DH_DEV_UNSUPP:
	142	case SCSI_DH_NOSYS:
	143	ret = -ENODEV;
	144	break;
2a8f7a03 HR	145	default:
	146	ret = -EINVAL;
	147	break;
	148	}
2930f817 HR	149	if (ret != -ENODEV)
	150	sdev_printk(KERN_ERR, sdev, "%s: Attach failed (%d)\n",
	151	scsi_dh->name, error);
1f12ffa5	152	module_put(scsi_dh->module);
ee14c674 CH	153	} else
ee14c674 CH	154	sdev->handler = scsi_dh;
1d520328	155
2a8f7a03	156	return ret;
765cbc6d HR	157	}
765cbc6d HR	158
1bab0de0 CH	159	/*
	160	* scsi_dh_handler_detach - Detach a device handler from a device
	161	* @sdev - SCSI device the device handler should be detached from
	162	*/
	163	static void scsi_dh_handler_detach(struct scsi_device *sdev)
6c10db72	164	{
ee14c674 CH	165	sdev->handler->detach(sdev);
	166	sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", sdev->handler->name);
	167	module_put(sdev->handler->module);
6c10db72 CS	168	}
6c10db72 CS	169
2930f817	170	void scsi_dh_add_device(struct scsi_device *sdev)
4c05ae52	171	{
d95dbff2 CH	172	struct scsi_device_handler *devinfo = NULL;
d95dbff2 CH	173	const char *drv;
4c05ae52	174
d95dbff2 CH	175	drv = scsi_dh_find_driver(sdev);
d95dbff2 CH	176	if (drv)
d6a32b98	177	devinfo = __scsi_dh_lookup(drv);
2930f817 HR	178	/*
	179	* device_handler is optional, so ignore errors
	180	* from scsi_dh_handler_attach()
	181	*/
086b91d0	182	if (devinfo)
2930f817	183	(void)scsi_dh_handler_attach(sdev, devinfo);
a6a8d9f8	184	}
a6a8d9f8	185
23695e41	186	void scsi_dh_release_device(struct scsi_device *sdev)
765cbc6d	187	{
ee14c674	188	if (sdev->handler)
1bab0de0	189	scsi_dh_handler_detach(sdev);
23695e41 JN	190	}
23695e41 JN	191
765cbc6d HR	192	/*
	193	* scsi_register_device_handler - register a device handler personality
	194	* module.
	195	* @scsi_dh - device handler to be registered.
	196	*
	197	* Returns 0 on success, -EBUSY if handler already registered.
	198	*/
	199	int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
	200	{
566079c8	201	if (__scsi_dh_lookup(scsi_dh->name))
765cbc6d HR	202	return -EBUSY;
765cbc6d HR	203
1f12ffa5 CH	204	if (!scsi_dh->attach \|\| !scsi_dh->detach)
	205	return -EINVAL;
	206
765cbc6d HR	207	spin_lock(&list_lock);
	208	list_add(&scsi_dh->list, &scsi_dh_list);
	209	spin_unlock(&list_lock);
940d7faa	210
765cbc6d HR	211	printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
	212
	213	return SCSI_DH_OK;
	214	}
	215	EXPORT_SYMBOL_GPL(scsi_register_device_handler);
	216
a6a8d9f8 CS	217	/*
	218	* scsi_unregister_device_handler - register a device handler personality
	219	* module.
	220	* @scsi_dh - device handler to be unregistered.
	221	*
	222	* Returns 0 on success, -ENODEV if handler not registered.
	223	*/
	224	int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
	225	{
566079c8	226	if (!__scsi_dh_lookup(scsi_dh->name))
765cbc6d	227	return -ENODEV;
a6a8d9f8	228
a6a8d9f8 CS	229	spin_lock(&list_lock);
	230	list_del(&scsi_dh->list);
	231	spin_unlock(&list_lock);
765cbc6d	232	printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
a6a8d9f8	233
765cbc6d	234	return SCSI_DH_OK;
a6a8d9f8 CS	235	}
	236	EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
	237
	238	/*
	239	* scsi_dh_activate - activate the path associated with the scsi_device
	240	* corresponding to the given request queue.
3ae31f6a CS	241	* Returns immediately without waiting for activation to be completed.
	242	* @q - Request queue that is associated with the scsi_device to be
	243	* activated.
	244	* @fn - Function to be called upon completion of the activation.
	245	* Function fn is called with data (below) and the error code.
	246	* Function fn may be called from the same calling context. So,
	247	* do not hold the lock in the caller which may be needed in fn.
	248	* @data - data passed to the function fn upon completion.
	249	*
a6a8d9f8	250	*/
3ae31f6a	251	int scsi_dh_activate(struct request_queue q, activate_complete fn, void data)
a6a8d9f8	252	{
a6a8d9f8	253	struct scsi_device *sdev;
e959ed9a	254	int err = SCSI_DH_NOSYS;
a6a8d9f8	255
857de6e0	256	sdev = scsi_device_from_queue(q);
a18a920c	257	if (!sdev) {
a18a920c MB	258	if (fn)
	259	fn(data, err);
	260	return err;
	261	}
	262
e959ed9a CH	263	if (!sdev->handler)
e959ed9a CH	264	goto out_fn;
710105fd	265	err = SCSI_DH_NOTCONN;
e959ed9a	266	if (sdev->sdev_state == SDEV_CANCEL \|\|
db422318	267	sdev->sdev_state == SDEV_DEL)
e959ed9a	268	goto out_fn;
a6a8d9f8	269
e959ed9a CH	270	err = SCSI_DH_DEV_OFFLINED;
	271	if (sdev->sdev_state == SDEV_OFFLINE)
	272	goto out_fn;
a6a8d9f8	273
ee14c674 CH	274	if (sdev->handler->activate)
ee14c674 CH	275	err = sdev->handler->activate(sdev, fn, data);
e959ed9a CH	276
	277	out_put_device:
	278	put_device(&sdev->sdev_gendev);
a6a8d9f8	279	return err;
e959ed9a CH	280
	281	out_fn:
	282	if (fn)
	283	fn(data, err);
	284	goto out_put_device;
a6a8d9f8 CS	285	}
	286	EXPORT_SYMBOL_GPL(scsi_dh_activate);
	287
18ee70c9 CS	288	/*
	289	* scsi_dh_set_params - set the parameters for the device as per the
	290	* string specified in params.
	291	* @q - Request queue that is associated with the scsi_device for
	292	* which the parameters to be set.
	293	* @params - parameters in the following format
	294	* "no_of_params\0param1\0param2\0param3\0...\0"
	295	* for example, string for 2 parameters with value 10 and 21
	296	* is specified as "2\010\021\0".
	297	*/
	298	int scsi_dh_set_params(struct request_queue q, const char params)
	299	{
18ee70c9	300	struct scsi_device *sdev;
e959ed9a	301	int err = -SCSI_DH_NOSYS;
18ee70c9	302
857de6e0	303	sdev = scsi_device_from_queue(q);
e959ed9a	304	if (!sdev)
18ee70c9	305	return err;
e959ed9a CH	306
	307	if (sdev->handler && sdev->handler->set_params)
	308	err = sdev->handler->set_params(sdev, params);
18ee70c9 CS	309	put_device(&sdev->sdev_gendev);
	310	return err;
	311	}
	312	EXPORT_SYMBOL_GPL(scsi_dh_set_params);
	313
ae11b1b3	314	/*
2a9ab40f	315	* scsi_dh_attach - Attach device handler
7e8a74b1 MS	316	* @q - Request queue that is associated with the scsi_device
7e8a74b1 MS	317	* the handler should be attached to
ae11b1b3 HR	318	* @name - name of the handler to attach
	319	*/
	320	int scsi_dh_attach(struct request_queue q, const char name)
	321	{
ae11b1b3 HR	322	struct scsi_device *sdev;
	323	struct scsi_device_handler *scsi_dh;
	324	int err = 0;
	325
857de6e0	326	sdev = scsi_device_from_queue(q);
e959ed9a CH	327	if (!sdev)
e959ed9a CH	328	return -ENODEV;
ae11b1b3	329
e959ed9a CH	330	scsi_dh = scsi_dh_lookup(name);
	331	if (!scsi_dh) {
	332	err = -EINVAL;
	333	goto out_put_device;
	334	}
ae11b1b3	335
ee14c674 CH	336	if (sdev->handler) {
ee14c674 CH	337	if (sdev->handler != scsi_dh)
1bab0de0 CH	338	err = -EBUSY;
1bab0de0 CH	339	goto out_put_device;
ae11b1b3	340	}
1bab0de0 CH	341
	342	err = scsi_dh_handler_attach(sdev, scsi_dh);
	343
	344	out_put_device:
ae11b1b3	345	put_device(&sdev->sdev_gendev);
1bab0de0	346	return err;
ae11b1b3	347	}
1bab0de0	348	EXPORT_SYMBOL_GPL(scsi_dh_attach);
ae11b1b3	349
7e8a74b1 MS	350	/*
	351	* scsi_dh_attached_handler_name - Get attached device handler's name
	352	* @q - Request queue that is associated with the scsi_device
	353	* that may have a device handler attached
	354	* @gfp - the GFP mask used in the kmalloc() call when allocating memory
	355	*
	356	* Returns name of attached handler, NULL if no handler is attached.
	357	* Caller must take care to free the returned string.
	358	*/
	359	const char scsi_dh_attached_handler_name(struct request_queue q, gfp_t gfp)
	360	{
7e8a74b1 MS	361	struct scsi_device *sdev;
	362	const char *handler_name = NULL;
	363
857de6e0	364	sdev = scsi_device_from_queue(q);
7e8a74b1 MS	365	if (!sdev)
	366	return NULL;
	367
ee14c674 CH	368	if (sdev->handler)
ee14c674 CH	369	handler_name = kstrdup(sdev->handler->name, gfp);
7e8a74b1 MS	370	put_device(&sdev->sdev_gendev);
	371	return handler_name;
	372	}
	373	EXPORT_SYMBOL_GPL(scsi_dh_attached_handler_name);