Merge remote-tracking branch 'moduleh/module.h-split'
[linux-2.6/next.git] / drivers / scsi / device_handler / scsi_dh.c
blob2a6cf73ec92df42e3df7789a9d543363a80ea268
1 /*
2 * SCSI device handler infrastruture.
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.
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.
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.
18 * Copyright IBM Corporation, 2007
19 * Authors:
20 * Chandra Seetharaman <sekharan@us.ibm.com>
21 * Mike Anderson <andmike@linux.vnet.ibm.com>
24 #include <linux/slab.h>
25 #include <linux/module.h>
26 #include <scsi/scsi_dh.h>
27 #include "../scsi_priv.h"
29 static DEFINE_SPINLOCK(list_lock);
30 static LIST_HEAD(scsi_dh_list);
31 static int scsi_dh_list_idx = 1;
33 static struct scsi_device_handler *get_device_handler(const char *name)
35 struct scsi_device_handler *tmp, *found = NULL;
37 spin_lock(&list_lock);
38 list_for_each_entry(tmp, &scsi_dh_list, list) {
39 if (!strncmp(tmp->name, name, strlen(tmp->name))) {
40 found = tmp;
41 break;
44 spin_unlock(&list_lock);
45 return found;
48 static struct scsi_device_handler *get_device_handler_by_idx(int idx)
50 struct scsi_device_handler *tmp, *found = NULL;
52 spin_lock(&list_lock);
53 list_for_each_entry(tmp, &scsi_dh_list, list) {
54 if (tmp->idx == idx) {
55 found = tmp;
56 break;
59 spin_unlock(&list_lock);
60 return found;
64 * device_handler_match_function - Match a device handler to a device
65 * @sdev - SCSI device to be tested
67 * Tests @sdev against the match function of all registered device_handler.
68 * Returns the found device handler or NULL if not found.
70 static struct scsi_device_handler *
71 device_handler_match_function(struct scsi_device *sdev)
73 struct scsi_device_handler *tmp_dh, *found_dh = NULL;
75 spin_lock(&list_lock);
76 list_for_each_entry(tmp_dh, &scsi_dh_list, list) {
77 if (tmp_dh->match && tmp_dh->match(sdev)) {
78 found_dh = tmp_dh;
79 break;
82 spin_unlock(&list_lock);
83 return found_dh;
87 * device_handler_match_devlist - Match a device handler to a device
88 * @sdev - SCSI device to be tested
90 * Tests @sdev against all device_handler registered in the devlist.
91 * Returns the found device handler or NULL if not found.
93 static struct scsi_device_handler *
94 device_handler_match_devlist(struct scsi_device *sdev)
96 int idx;
98 idx = scsi_get_device_flags_keyed(sdev, sdev->vendor, sdev->model,
99 SCSI_DEVINFO_DH);
100 return get_device_handler_by_idx(idx);
104 * device_handler_match - Attach a device handler to a device
105 * @scsi_dh - The device handler to match against or NULL
106 * @sdev - SCSI device to be tested against @scsi_dh
108 * Tests @sdev against the device handler @scsi_dh or against
109 * all registered device_handler if @scsi_dh == NULL.
110 * Returns the found device handler or NULL if not found.
112 static struct scsi_device_handler *
113 device_handler_match(struct scsi_device_handler *scsi_dh,
114 struct scsi_device *sdev)
116 struct scsi_device_handler *found_dh;
118 found_dh = device_handler_match_function(sdev);
119 if (!found_dh)
120 found_dh = device_handler_match_devlist(sdev);
122 if (scsi_dh && found_dh != scsi_dh)
123 found_dh = NULL;
125 return found_dh;
129 * scsi_dh_handler_attach - Attach a device handler to a device
130 * @sdev - SCSI device the device handler should attach to
131 * @scsi_dh - The device handler to attach
133 static int scsi_dh_handler_attach(struct scsi_device *sdev,
134 struct scsi_device_handler *scsi_dh)
136 int err = 0;
138 if (sdev->scsi_dh_data) {
139 if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
140 err = -EBUSY;
141 else
142 kref_get(&sdev->scsi_dh_data->kref);
143 } else if (scsi_dh->attach) {
144 err = scsi_dh->attach(sdev);
145 if (!err) {
146 kref_init(&sdev->scsi_dh_data->kref);
147 sdev->scsi_dh_data->sdev = sdev;
150 return err;
153 static void __detach_handler (struct kref *kref)
155 struct scsi_dh_data *scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
156 scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev);
160 * scsi_dh_handler_detach - Detach a device handler from a device
161 * @sdev - SCSI device the device handler should be detached from
162 * @scsi_dh - Device handler to be detached
164 * Detach from a device handler. If a device handler is specified,
165 * only detach if the currently attached handler matches @scsi_dh.
167 static void scsi_dh_handler_detach(struct scsi_device *sdev,
168 struct scsi_device_handler *scsi_dh)
170 if (!sdev->scsi_dh_data)
171 return;
173 if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
174 return;
176 if (!scsi_dh)
177 scsi_dh = sdev->scsi_dh_data->scsi_dh;
179 if (scsi_dh && scsi_dh->detach)
180 kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
184 * Functions for sysfs attribute 'dh_state'
186 static ssize_t
187 store_dh_state(struct device *dev, struct device_attribute *attr,
188 const char *buf, size_t count)
190 struct scsi_device *sdev = to_scsi_device(dev);
191 struct scsi_device_handler *scsi_dh;
192 int err = -EINVAL;
194 if (sdev->sdev_state == SDEV_CANCEL ||
195 sdev->sdev_state == SDEV_DEL)
196 return -ENODEV;
198 if (!sdev->scsi_dh_data) {
200 * Attach to a device handler
202 if (!(scsi_dh = get_device_handler(buf)))
203 return err;
204 err = scsi_dh_handler_attach(sdev, scsi_dh);
205 } else {
206 scsi_dh = sdev->scsi_dh_data->scsi_dh;
207 if (!strncmp(buf, "detach", 6)) {
209 * Detach from a device handler
211 scsi_dh_handler_detach(sdev, scsi_dh);
212 err = 0;
213 } else if (!strncmp(buf, "activate", 8)) {
215 * Activate a device handler
217 if (scsi_dh->activate)
218 err = scsi_dh->activate(sdev, NULL, NULL);
219 else
220 err = 0;
224 return err<0?err:count;
227 static ssize_t
228 show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
230 struct scsi_device *sdev = to_scsi_device(dev);
232 if (!sdev->scsi_dh_data)
233 return snprintf(buf, 20, "detached\n");
235 return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
238 static struct device_attribute scsi_dh_state_attr =
239 __ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
240 store_dh_state);
243 * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
245 static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
247 struct scsi_device *sdev;
248 int err;
250 if (!scsi_is_sdev_device(dev))
251 return 0;
253 sdev = to_scsi_device(dev);
255 err = device_create_file(&sdev->sdev_gendev,
256 &scsi_dh_state_attr);
258 return 0;
262 * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
264 static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
266 struct scsi_device *sdev;
268 if (!scsi_is_sdev_device(dev))
269 return 0;
271 sdev = to_scsi_device(dev);
273 device_remove_file(&sdev->sdev_gendev,
274 &scsi_dh_state_attr);
276 return 0;
280 * scsi_dh_notifier - notifier chain callback
282 static int scsi_dh_notifier(struct notifier_block *nb,
283 unsigned long action, void *data)
285 struct device *dev = data;
286 struct scsi_device *sdev;
287 int err = 0;
288 struct scsi_device_handler *devinfo = NULL;
290 if (!scsi_is_sdev_device(dev))
291 return 0;
293 sdev = to_scsi_device(dev);
295 if (action == BUS_NOTIFY_ADD_DEVICE) {
296 err = device_create_file(dev, &scsi_dh_state_attr);
297 /* don't care about err */
298 devinfo = device_handler_match(NULL, sdev);
299 if (devinfo)
300 err = scsi_dh_handler_attach(sdev, devinfo);
301 } else if (action == BUS_NOTIFY_DEL_DEVICE) {
302 device_remove_file(dev, &scsi_dh_state_attr);
303 scsi_dh_handler_detach(sdev, NULL);
305 return err;
309 * scsi_dh_notifier_add - Callback for scsi_register_device_handler
311 static int scsi_dh_notifier_add(struct device *dev, void *data)
313 struct scsi_device_handler *scsi_dh = data;
314 struct scsi_device *sdev;
316 if (!scsi_is_sdev_device(dev))
317 return 0;
319 if (!get_device(dev))
320 return 0;
322 sdev = to_scsi_device(dev);
324 if (device_handler_match(scsi_dh, sdev))
325 scsi_dh_handler_attach(sdev, scsi_dh);
327 put_device(dev);
329 return 0;
333 * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
335 static int scsi_dh_notifier_remove(struct device *dev, void *data)
337 struct scsi_device_handler *scsi_dh = data;
338 struct scsi_device *sdev;
340 if (!scsi_is_sdev_device(dev))
341 return 0;
343 if (!get_device(dev))
344 return 0;
346 sdev = to_scsi_device(dev);
348 scsi_dh_handler_detach(sdev, scsi_dh);
350 put_device(dev);
352 return 0;
356 * scsi_register_device_handler - register a device handler personality
357 * module.
358 * @scsi_dh - device handler to be registered.
360 * Returns 0 on success, -EBUSY if handler already registered.
362 int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
364 int i;
366 if (get_device_handler(scsi_dh->name))
367 return -EBUSY;
369 spin_lock(&list_lock);
370 scsi_dh->idx = scsi_dh_list_idx++;
371 list_add(&scsi_dh->list, &scsi_dh_list);
372 spin_unlock(&list_lock);
374 for (i = 0; scsi_dh->devlist && scsi_dh->devlist[i].vendor; i++) {
375 scsi_dev_info_list_add_keyed(0,
376 scsi_dh->devlist[i].vendor,
377 scsi_dh->devlist[i].model,
378 NULL,
379 scsi_dh->idx,
380 SCSI_DEVINFO_DH);
383 bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
384 printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
386 return SCSI_DH_OK;
388 EXPORT_SYMBOL_GPL(scsi_register_device_handler);
391 * scsi_unregister_device_handler - register a device handler personality
392 * module.
393 * @scsi_dh - device handler to be unregistered.
395 * Returns 0 on success, -ENODEV if handler not registered.
397 int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
399 int i;
401 if (!get_device_handler(scsi_dh->name))
402 return -ENODEV;
404 bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
405 scsi_dh_notifier_remove);
407 for (i = 0; scsi_dh->devlist && scsi_dh->devlist[i].vendor; i++) {
408 scsi_dev_info_list_del_keyed(scsi_dh->devlist[i].vendor,
409 scsi_dh->devlist[i].model,
410 SCSI_DEVINFO_DH);
413 spin_lock(&list_lock);
414 list_del(&scsi_dh->list);
415 spin_unlock(&list_lock);
416 printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
418 return SCSI_DH_OK;
420 EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
423 * scsi_dh_activate - activate the path associated with the scsi_device
424 * corresponding to the given request queue.
425 * Returns immediately without waiting for activation to be completed.
426 * @q - Request queue that is associated with the scsi_device to be
427 * activated.
428 * @fn - Function to be called upon completion of the activation.
429 * Function fn is called with data (below) and the error code.
430 * Function fn may be called from the same calling context. So,
431 * do not hold the lock in the caller which may be needed in fn.
432 * @data - data passed to the function fn upon completion.
435 int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
437 int err = 0;
438 unsigned long flags;
439 struct scsi_device *sdev;
440 struct scsi_device_handler *scsi_dh = NULL;
441 struct device *dev = NULL;
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 dev = get_device(&sdev->sdev_gendev);
448 if (!scsi_dh || !dev ||
449 sdev->sdev_state == SDEV_CANCEL ||
450 sdev->sdev_state == SDEV_DEL)
451 err = SCSI_DH_NOSYS;
452 if (sdev->sdev_state == SDEV_OFFLINE)
453 err = SCSI_DH_DEV_OFFLINED;
454 spin_unlock_irqrestore(q->queue_lock, flags);
456 if (err) {
457 if (fn)
458 fn(data, err);
459 goto out;
462 if (scsi_dh->activate)
463 err = scsi_dh->activate(sdev, fn, data);
464 out:
465 put_device(dev);
466 return err;
468 EXPORT_SYMBOL_GPL(scsi_dh_activate);
471 * scsi_dh_set_params - set the parameters for the device as per the
472 * string specified in params.
473 * @q - Request queue that is associated with the scsi_device for
474 * which the parameters to be set.
475 * @params - parameters in the following format
476 * "no_of_params\0param1\0param2\0param3\0...\0"
477 * for example, string for 2 parameters with value 10 and 21
478 * is specified as "2\010\021\0".
480 int scsi_dh_set_params(struct request_queue *q, const char *params)
482 int err = -SCSI_DH_NOSYS;
483 unsigned long flags;
484 struct scsi_device *sdev;
485 struct scsi_device_handler *scsi_dh = NULL;
487 spin_lock_irqsave(q->queue_lock, flags);
488 sdev = q->queuedata;
489 if (sdev && sdev->scsi_dh_data)
490 scsi_dh = sdev->scsi_dh_data->scsi_dh;
491 if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
492 err = 0;
493 spin_unlock_irqrestore(q->queue_lock, flags);
495 if (err)
496 return err;
497 err = scsi_dh->set_params(sdev, params);
498 put_device(&sdev->sdev_gendev);
499 return err;
501 EXPORT_SYMBOL_GPL(scsi_dh_set_params);
504 * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
505 * the given name. FALSE(0) otherwise.
506 * @name - name of the device handler.
508 int scsi_dh_handler_exist(const char *name)
510 return (get_device_handler(name) != NULL);
512 EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
515 * scsi_dh_attach - Attach device handler
516 * @sdev - sdev the handler should be attached to
517 * @name - name of the handler to attach
519 int scsi_dh_attach(struct request_queue *q, const char *name)
521 unsigned long flags;
522 struct scsi_device *sdev;
523 struct scsi_device_handler *scsi_dh;
524 int err = 0;
526 scsi_dh = get_device_handler(name);
527 if (!scsi_dh)
528 return -EINVAL;
530 spin_lock_irqsave(q->queue_lock, flags);
531 sdev = q->queuedata;
532 if (!sdev || !get_device(&sdev->sdev_gendev))
533 err = -ENODEV;
534 spin_unlock_irqrestore(q->queue_lock, flags);
536 if (!err) {
537 err = scsi_dh_handler_attach(sdev, scsi_dh);
538 put_device(&sdev->sdev_gendev);
540 return err;
542 EXPORT_SYMBOL_GPL(scsi_dh_attach);
545 * scsi_dh_detach - Detach device handler
546 * @sdev - sdev the handler should be detached from
548 * This function will detach the device handler only
549 * if the sdev is not part of the internal list, ie
550 * if it has been attached manually.
552 void scsi_dh_detach(struct request_queue *q)
554 unsigned long flags;
555 struct scsi_device *sdev;
556 struct scsi_device_handler *scsi_dh = NULL;
558 spin_lock_irqsave(q->queue_lock, flags);
559 sdev = q->queuedata;
560 if (!sdev || !get_device(&sdev->sdev_gendev))
561 sdev = NULL;
562 spin_unlock_irqrestore(q->queue_lock, flags);
564 if (!sdev)
565 return;
567 if (sdev->scsi_dh_data) {
568 scsi_dh = sdev->scsi_dh_data->scsi_dh;
569 scsi_dh_handler_detach(sdev, scsi_dh);
571 put_device(&sdev->sdev_gendev);
573 EXPORT_SYMBOL_GPL(scsi_dh_detach);
575 static struct notifier_block scsi_dh_nb = {
576 .notifier_call = scsi_dh_notifier
579 static int __init scsi_dh_init(void)
581 int r;
583 r = scsi_dev_info_add_list(SCSI_DEVINFO_DH, "SCSI Device Handler");
584 if (r)
585 return r;
587 r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
589 if (!r)
590 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
591 scsi_dh_sysfs_attr_add);
593 return r;
596 static void __exit scsi_dh_exit(void)
598 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
599 scsi_dh_sysfs_attr_remove);
600 bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
601 scsi_dev_info_remove_list(SCSI_DEVINFO_DH);
604 module_init(scsi_dh_init);
605 module_exit(scsi_dh_exit);
607 MODULE_DESCRIPTION("SCSI device handler");
608 MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
609 MODULE_LICENSE("GPL");