Loading...
Note: File does not exist in v4.6.
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
24#include <linux/slab.h>
25#include <scsi/scsi_dh.h>
26#include "../scsi_priv.h"
27
28static DEFINE_SPINLOCK(list_lock);
29static LIST_HEAD(scsi_dh_list);
30static int scsi_dh_list_idx = 1;
31
32static 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) {
38 if (!strncmp(tmp->name, name, strlen(tmp->name))) {
39 found = tmp;
40 break;
41 }
42 }
43 spin_unlock(&list_lock);
44 return found;
45}
46
47static struct scsi_device_handler *get_device_handler_by_idx(int idx)
48{
49 struct scsi_device_handler *tmp, *found = NULL;
50
51 spin_lock(&list_lock);
52 list_for_each_entry(tmp, &scsi_dh_list, list) {
53 if (tmp->idx == idx) {
54 found = tmp;
55 break;
56 }
57 }
58 spin_unlock(&list_lock);
59 return found;
60}
61
62/*
63 * device_handler_match - Attach a device handler to a device
64 * @scsi_dh - The device handler to match against or NULL
65 * @sdev - SCSI device to be tested against @scsi_dh
66 *
67 * Tests @sdev against the device handler @scsi_dh or against
68 * all registered device_handler if @scsi_dh == NULL.
69 * Returns the found device handler or NULL if not found.
70 */
71static struct scsi_device_handler *
72device_handler_match(struct scsi_device_handler *scsi_dh,
73 struct scsi_device *sdev)
74{
75 struct scsi_device_handler *found_dh = NULL;
76 int idx;
77
78 idx = scsi_get_device_flags_keyed(sdev, sdev->vendor, sdev->model,
79 SCSI_DEVINFO_DH);
80 found_dh = get_device_handler_by_idx(idx);
81
82 if (scsi_dh && found_dh != scsi_dh)
83 found_dh = NULL;
84
85 return found_dh;
86}
87
88/*
89 * scsi_dh_handler_attach - Attach a device handler to a device
90 * @sdev - SCSI device the device handler should attach to
91 * @scsi_dh - The device handler to attach
92 */
93static int scsi_dh_handler_attach(struct scsi_device *sdev,
94 struct scsi_device_handler *scsi_dh)
95{
96 int err = 0;
97
98 if (sdev->scsi_dh_data) {
99 if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
100 err = -EBUSY;
101 else
102 kref_get(&sdev->scsi_dh_data->kref);
103 } else if (scsi_dh->attach) {
104 err = scsi_dh->attach(sdev);
105 if (!err) {
106 kref_init(&sdev->scsi_dh_data->kref);
107 sdev->scsi_dh_data->sdev = sdev;
108 }
109 }
110 return err;
111}
112
113static void __detach_handler (struct kref *kref)
114{
115 struct scsi_dh_data *scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
116 scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev);
117}
118
119/*
120 * scsi_dh_handler_detach - Detach a device handler from a device
121 * @sdev - SCSI device the device handler should be detached from
122 * @scsi_dh - Device handler to be detached
123 *
124 * Detach from a device handler. If a device handler is specified,
125 * only detach if the currently attached handler matches @scsi_dh.
126 */
127static void scsi_dh_handler_detach(struct scsi_device *sdev,
128 struct scsi_device_handler *scsi_dh)
129{
130 if (!sdev->scsi_dh_data)
131 return;
132
133 if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
134 return;
135
136 if (!scsi_dh)
137 scsi_dh = sdev->scsi_dh_data->scsi_dh;
138
139 if (scsi_dh && scsi_dh->detach)
140 kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
141}
142
143/*
144 * Functions for sysfs attribute 'dh_state'
145 */
146static ssize_t
147store_dh_state(struct device *dev, struct device_attribute *attr,
148 const char *buf, size_t count)
149{
150 struct scsi_device *sdev = to_scsi_device(dev);
151 struct scsi_device_handler *scsi_dh;
152 int err = -EINVAL;
153
154 if (!sdev->scsi_dh_data) {
155 /*
156 * Attach to a device handler
157 */
158 if (!(scsi_dh = get_device_handler(buf)))
159 return err;
160 err = scsi_dh_handler_attach(sdev, scsi_dh);
161 } else {
162 scsi_dh = sdev->scsi_dh_data->scsi_dh;
163 if (!strncmp(buf, "detach", 6)) {
164 /*
165 * Detach from a device handler
166 */
167 scsi_dh_handler_detach(sdev, scsi_dh);
168 err = 0;
169 } else if (!strncmp(buf, "activate", 8)) {
170 /*
171 * Activate a device handler
172 */
173 if (scsi_dh->activate)
174 err = scsi_dh->activate(sdev, NULL, NULL);
175 else
176 err = 0;
177 }
178 }
179
180 return err<0?err:count;
181}
182
183static ssize_t
184show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
185{
186 struct scsi_device *sdev = to_scsi_device(dev);
187
188 if (!sdev->scsi_dh_data)
189 return snprintf(buf, 20, "detached\n");
190
191 return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
192}
193
194static struct device_attribute scsi_dh_state_attr =
195 __ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
196 store_dh_state);
197
198/*
199 * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
200 */
201static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
202{
203 struct scsi_device *sdev;
204 int err;
205
206 if (!scsi_is_sdev_device(dev))
207 return 0;
208
209 sdev = to_scsi_device(dev);
210
211 err = device_create_file(&sdev->sdev_gendev,
212 &scsi_dh_state_attr);
213
214 return 0;
215}
216
217/*
218 * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
219 */
220static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
221{
222 struct scsi_device *sdev;
223
224 if (!scsi_is_sdev_device(dev))
225 return 0;
226
227 sdev = to_scsi_device(dev);
228
229 device_remove_file(&sdev->sdev_gendev,
230 &scsi_dh_state_attr);
231
232 return 0;
233}
234
235/*
236 * scsi_dh_notifier - notifier chain callback
237 */
238static int scsi_dh_notifier(struct notifier_block *nb,
239 unsigned long action, void *data)
240{
241 struct device *dev = data;
242 struct scsi_device *sdev;
243 int err = 0;
244 struct scsi_device_handler *devinfo = NULL;
245
246 if (!scsi_is_sdev_device(dev))
247 return 0;
248
249 sdev = to_scsi_device(dev);
250
251 if (action == BUS_NOTIFY_ADD_DEVICE) {
252 err = device_create_file(dev, &scsi_dh_state_attr);
253 /* don't care about err */
254 devinfo = device_handler_match(NULL, sdev);
255 if (devinfo)
256 err = scsi_dh_handler_attach(sdev, devinfo);
257 } else if (action == BUS_NOTIFY_DEL_DEVICE) {
258 device_remove_file(dev, &scsi_dh_state_attr);
259 scsi_dh_handler_detach(sdev, NULL);
260 }
261 return err;
262}
263
264/*
265 * scsi_dh_notifier_add - Callback for scsi_register_device_handler
266 */
267static int scsi_dh_notifier_add(struct device *dev, void *data)
268{
269 struct scsi_device_handler *scsi_dh = data;
270 struct scsi_device *sdev;
271
272 if (!scsi_is_sdev_device(dev))
273 return 0;
274
275 if (!get_device(dev))
276 return 0;
277
278 sdev = to_scsi_device(dev);
279
280 if (device_handler_match(scsi_dh, sdev))
281 scsi_dh_handler_attach(sdev, scsi_dh);
282
283 put_device(dev);
284
285 return 0;
286}
287
288/*
289 * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
290 */
291static int scsi_dh_notifier_remove(struct device *dev, void *data)
292{
293 struct scsi_device_handler *scsi_dh = data;
294 struct scsi_device *sdev;
295
296 if (!scsi_is_sdev_device(dev))
297 return 0;
298
299 if (!get_device(dev))
300 return 0;
301
302 sdev = to_scsi_device(dev);
303
304 scsi_dh_handler_detach(sdev, scsi_dh);
305
306 put_device(dev);
307
308 return 0;
309}
310
311/*
312 * scsi_register_device_handler - register a device handler personality
313 * module.
314 * @scsi_dh - device handler to be registered.
315 *
316 * Returns 0 on success, -EBUSY if handler already registered.
317 */
318int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
319{
320 int i;
321
322 if (get_device_handler(scsi_dh->name))
323 return -EBUSY;
324
325 spin_lock(&list_lock);
326 scsi_dh->idx = scsi_dh_list_idx++;
327 list_add(&scsi_dh->list, &scsi_dh_list);
328 spin_unlock(&list_lock);
329
330 for (i = 0; scsi_dh->devlist[i].vendor; i++) {
331 scsi_dev_info_list_add_keyed(0,
332 scsi_dh->devlist[i].vendor,
333 scsi_dh->devlist[i].model,
334 NULL,
335 scsi_dh->idx,
336 SCSI_DEVINFO_DH);
337 }
338
339 bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
340 printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
341
342 return SCSI_DH_OK;
343}
344EXPORT_SYMBOL_GPL(scsi_register_device_handler);
345
346/*
347 * scsi_unregister_device_handler - register a device handler personality
348 * module.
349 * @scsi_dh - device handler to be unregistered.
350 *
351 * Returns 0 on success, -ENODEV if handler not registered.
352 */
353int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
354{
355 int i;
356
357 if (!get_device_handler(scsi_dh->name))
358 return -ENODEV;
359
360 bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
361 scsi_dh_notifier_remove);
362
363 for (i = 0; scsi_dh->devlist[i].vendor; i++) {
364 scsi_dev_info_list_del_keyed(scsi_dh->devlist[i].vendor,
365 scsi_dh->devlist[i].model,
366 SCSI_DEVINFO_DH);
367 }
368
369 spin_lock(&list_lock);
370 list_del(&scsi_dh->list);
371 spin_unlock(&list_lock);
372 printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
373
374 return SCSI_DH_OK;
375}
376EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
377
378/*
379 * scsi_dh_activate - activate the path associated with the scsi_device
380 * corresponding to the given request queue.
381 * Returns immediately without waiting for activation to be completed.
382 * @q - Request queue that is associated with the scsi_device to be
383 * activated.
384 * @fn - Function to be called upon completion of the activation.
385 * Function fn is called with data (below) and the error code.
386 * Function fn may be called from the same calling context. So,
387 * do not hold the lock in the caller which may be needed in fn.
388 * @data - data passed to the function fn upon completion.
389 *
390 */
391int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
392{
393 int err = 0;
394 unsigned long flags;
395 struct scsi_device *sdev;
396 struct scsi_device_handler *scsi_dh = NULL;
397 struct device *dev = NULL;
398
399 spin_lock_irqsave(q->queue_lock, flags);
400 sdev = q->queuedata;
401 if (sdev && sdev->scsi_dh_data)
402 scsi_dh = sdev->scsi_dh_data->scsi_dh;
403 dev = get_device(&sdev->sdev_gendev);
404 if (!scsi_dh || !dev ||
405 sdev->sdev_state == SDEV_CANCEL ||
406 sdev->sdev_state == SDEV_DEL)
407 err = SCSI_DH_NOSYS;
408 if (sdev->sdev_state == SDEV_OFFLINE)
409 err = SCSI_DH_DEV_OFFLINED;
410 spin_unlock_irqrestore(q->queue_lock, flags);
411
412 if (err) {
413 if (fn)
414 fn(data, err);
415 goto out;
416 }
417
418 if (scsi_dh->activate)
419 err = scsi_dh->activate(sdev, fn, data);
420out:
421 put_device(dev);
422 return err;
423}
424EXPORT_SYMBOL_GPL(scsi_dh_activate);
425
426/*
427 * scsi_dh_set_params - set the parameters for the device as per the
428 * string specified in params.
429 * @q - Request queue that is associated with the scsi_device for
430 * which the parameters to be set.
431 * @params - parameters in the following format
432 * "no_of_params\0param1\0param2\0param3\0...\0"
433 * for example, string for 2 parameters with value 10 and 21
434 * is specified as "2\010\021\0".
435 */
436int scsi_dh_set_params(struct request_queue *q, const char *params)
437{
438 int err = -SCSI_DH_NOSYS;
439 unsigned long flags;
440 struct scsi_device *sdev;
441 struct scsi_device_handler *scsi_dh = NULL;
442
443 spin_lock_irqsave(q->queue_lock, flags);
444 sdev = q->queuedata;
445 if (sdev && sdev->scsi_dh_data)
446 scsi_dh = sdev->scsi_dh_data->scsi_dh;
447 if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
448 err = 0;
449 spin_unlock_irqrestore(q->queue_lock, flags);
450
451 if (err)
452 return err;
453 err = scsi_dh->set_params(sdev, params);
454 put_device(&sdev->sdev_gendev);
455 return err;
456}
457EXPORT_SYMBOL_GPL(scsi_dh_set_params);
458
459/*
460 * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
461 * the given name. FALSE(0) otherwise.
462 * @name - name of the device handler.
463 */
464int scsi_dh_handler_exist(const char *name)
465{
466 return (get_device_handler(name) != NULL);
467}
468EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
469
470/*
471 * scsi_dh_handler_attach - Attach device handler
472 * @sdev - sdev the handler should be attached to
473 * @name - name of the handler to attach
474 */
475int scsi_dh_attach(struct request_queue *q, const char *name)
476{
477 unsigned long flags;
478 struct scsi_device *sdev;
479 struct scsi_device_handler *scsi_dh;
480 int err = 0;
481
482 scsi_dh = get_device_handler(name);
483 if (!scsi_dh)
484 return -EINVAL;
485
486 spin_lock_irqsave(q->queue_lock, flags);
487 sdev = q->queuedata;
488 if (!sdev || !get_device(&sdev->sdev_gendev))
489 err = -ENODEV;
490 spin_unlock_irqrestore(q->queue_lock, flags);
491
492 if (!err) {
493 err = scsi_dh_handler_attach(sdev, scsi_dh);
494 put_device(&sdev->sdev_gendev);
495 }
496 return err;
497}
498EXPORT_SYMBOL_GPL(scsi_dh_attach);
499
500/*
501 * scsi_dh_handler_detach - Detach device handler
502 * @sdev - sdev the handler should be detached from
503 *
504 * This function will detach the device handler only
505 * if the sdev is not part of the internal list, ie
506 * if it has been attached manually.
507 */
508void scsi_dh_detach(struct request_queue *q)
509{
510 unsigned long flags;
511 struct scsi_device *sdev;
512 struct scsi_device_handler *scsi_dh = NULL;
513
514 spin_lock_irqsave(q->queue_lock, flags);
515 sdev = q->queuedata;
516 if (!sdev || !get_device(&sdev->sdev_gendev))
517 sdev = NULL;
518 spin_unlock_irqrestore(q->queue_lock, flags);
519
520 if (!sdev)
521 return;
522
523 if (sdev->scsi_dh_data) {
524 scsi_dh = sdev->scsi_dh_data->scsi_dh;
525 scsi_dh_handler_detach(sdev, scsi_dh);
526 }
527 put_device(&sdev->sdev_gendev);
528}
529EXPORT_SYMBOL_GPL(scsi_dh_detach);
530
531static struct notifier_block scsi_dh_nb = {
532 .notifier_call = scsi_dh_notifier
533};
534
535static int __init scsi_dh_init(void)
536{
537 int r;
538
539 r = scsi_dev_info_add_list(SCSI_DEVINFO_DH, "SCSI Device Handler");
540 if (r)
541 return r;
542
543 r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
544
545 if (!r)
546 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
547 scsi_dh_sysfs_attr_add);
548
549 return r;
550}
551
552static void __exit scsi_dh_exit(void)
553{
554 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
555 scsi_dh_sysfs_attr_remove);
556 bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
557 scsi_dev_info_remove_list(SCSI_DEVINFO_DH);
558}
559
560module_init(scsi_dh_init);
561module_exit(scsi_dh_exit);
562
563MODULE_DESCRIPTION("SCSI device handler");
564MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
565MODULE_LICENSE("GPL");