summaryrefslogtreecommitdiffstats
path: root/drivers/scsi/device_handler/scsi_dh.c
blob: e90df9dd3e6525ed0db89c60525428b91ee329a3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
/*
 * 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 <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;
}

static int device_handler_match(struct scsi_device_handler *tmp,
				struct scsi_device *sdev)
{
	int i;

	for(i = 0; tmp->devlist[i].vendor; i++) {
		if (!strncmp(sdev->vendor, tmp->devlist[i].vendor,
			     strlen(tmp->devlist[i].vendor)) &&
		    !strncmp(sdev->model, tmp->devlist[i].model,
			     strlen(tmp->devlist[i].model))) {
			return 1;
		}
	}

	return 0;
}

/*
 * 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 if (scsi_dh->attach)
		err = scsi_dh->attach(sdev);

	return err;
}

/*
 * 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)
		scsi_dh->detach(sdev);
}

/*
 * 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->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);
			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 *tmp, *devinfo = NULL;

	if (!scsi_is_sdev_device(dev))
		return 0;

	sdev = to_scsi_device(dev);

	spin_lock(&list_lock);
	list_for_each_entry(tmp, &scsi_dh_list, list) {
		if (device_handler_match(tmp, sdev)) {
			devinfo = tmp;
			break;
		}
	}
	spin_unlock(&list_lock);

	if (!devinfo)
		goto out;

	if (action == BUS_NOTIFY_ADD_DEVICE) {
		err = scsi_dh_handler_attach(sdev, devinfo);
		if (!err)
			err = device_create_file(dev, &scsi_dh_state_attr);
	} else if (action == BUS_NOTIFY_DEL_DEVICE) {
		device_remove_file(dev, &scsi_dh_state_attr);
		scsi_dh_handler_detach(sdev, NULL);
	}
out:
	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.
 * @q - Request queue that is associated with the scsi_device to be
 *      activated.
 */
int scsi_dh_activate(struct request_queue *q)
{
	int err = 0;
	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 || !get_device(&sdev->sdev_gendev))
		err = SCSI_DH_NOSYS;
	spin_unlock_irqrestore(q->queue_lock, flags);

	if (err)
		return err;

	if (scsi_dh->activate)
		err = scsi_dh->activate(sdev);
	put_device(&sdev->sdev_gendev);
	return err;
}
EXPORT_SYMBOL_GPL(scsi_dh_activate);

/*
 * 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);

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");
OpenPOWER on IntegriCloud