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
20 * Chandra Seetharaman <sekharan@us.ibm.com>
21 * Mike Anderson <andmike@linux.vnet.ibm.com>
24 #include <linux/slab.h>
25 #include <scsi/scsi_dh.h>
26 #include "../scsi_priv.h"
28 static DEFINE_SPINLOCK(list_lock);
29 static LIST_HEAD(scsi_dh_list);
30 static int scsi_dh_list_idx = 1;
32 static struct scsi_device_handler *get_device_handler(const char *name)
34 struct scsi_device_handler *tmp, *found = NULL;
36 spin_lock(&list_lock);
37 list_for_each_entry(tmp, &scsi_dh_list, list) {
38 if (!strncmp(tmp->name, name, strlen(tmp->name))) {
43 spin_unlock(&list_lock);
47 static struct scsi_device_handler *get_device_handler_by_idx(int idx)
49 struct scsi_device_handler *tmp, *found = NULL;
51 spin_lock(&list_lock);
52 list_for_each_entry(tmp, &scsi_dh_list, list) {
53 if (tmp->idx == idx) {
58 spin_unlock(&list_lock);
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
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.
71 static struct scsi_device_handler *
72 device_handler_match(struct scsi_device_handler *scsi_dh,
73 struct scsi_device *sdev)
75 struct scsi_device_handler *found_dh = NULL;
78 idx = scsi_get_device_flags_keyed(sdev, sdev->vendor, sdev->model,
80 found_dh = get_device_handler_by_idx(idx);
82 if (scsi_dh && found_dh != scsi_dh)
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
93 static int scsi_dh_handler_attach(struct scsi_device *sdev,
94 struct scsi_device_handler *scsi_dh)
98 if (sdev->scsi_dh_data) {
99 if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
102 kref_get(&sdev->scsi_dh_data->kref);
103 } else if (scsi_dh->attach) {
104 err = scsi_dh->attach(sdev);
106 kref_init(&sdev->scsi_dh_data->kref);
107 sdev->scsi_dh_data->sdev = sdev;
113 static void __detach_handler (struct kref *kref)
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);
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
124 * Detach from a device handler. If a device handler is specified,
125 * only detach if the currently attached handler matches @scsi_dh.
127 static void scsi_dh_handler_detach(struct scsi_device *sdev,
128 struct scsi_device_handler *scsi_dh)
130 if (!sdev->scsi_dh_data)
133 if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
137 scsi_dh = sdev->scsi_dh_data->scsi_dh;
139 if (scsi_dh && scsi_dh->detach)
140 kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
144 * Functions for sysfs attribute 'dh_state'
147 store_dh_state(struct device *dev, struct device_attribute *attr,
148 const char *buf, size_t count)
150 struct scsi_device *sdev = to_scsi_device(dev);
151 struct scsi_device_handler *scsi_dh;
154 if (!sdev->scsi_dh_data) {
156 * Attach to a device handler
158 if (!(scsi_dh = get_device_handler(buf)))
160 err = scsi_dh_handler_attach(sdev, scsi_dh);
162 scsi_dh = sdev->scsi_dh_data->scsi_dh;
163 if (!strncmp(buf, "detach", 6)) {
165 * Detach from a device handler
167 scsi_dh_handler_detach(sdev, scsi_dh);
169 } else if (!strncmp(buf, "activate", 8)) {
171 * Activate a device handler
173 if (scsi_dh->activate)
174 err = scsi_dh->activate(sdev, NULL, NULL);
180 return err<0?err:count;
184 show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
186 struct scsi_device *sdev = to_scsi_device(dev);
188 if (!sdev->scsi_dh_data)
189 return snprintf(buf, 20, "detached\n");
191 return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
194 static struct device_attribute scsi_dh_state_attr =
195 __ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
199 * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
201 static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
203 struct scsi_device *sdev;
206 if (!scsi_is_sdev_device(dev))
209 sdev = to_scsi_device(dev);
211 err = device_create_file(&sdev->sdev_gendev,
212 &scsi_dh_state_attr);
218 * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
220 static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
222 struct scsi_device *sdev;
224 if (!scsi_is_sdev_device(dev))
227 sdev = to_scsi_device(dev);
229 device_remove_file(&sdev->sdev_gendev,
230 &scsi_dh_state_attr);
236 * scsi_dh_notifier - notifier chain callback
238 static int scsi_dh_notifier(struct notifier_block *nb,
239 unsigned long action, void *data)
241 struct device *dev = data;
242 struct scsi_device *sdev;
244 struct scsi_device_handler *devinfo = NULL;
246 if (!scsi_is_sdev_device(dev))
249 sdev = to_scsi_device(dev);
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);
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);
265 * scsi_dh_notifier_add - Callback for scsi_register_device_handler
267 static int scsi_dh_notifier_add(struct device *dev, void *data)
269 struct scsi_device_handler *scsi_dh = data;
270 struct scsi_device *sdev;
272 if (!scsi_is_sdev_device(dev))
275 if (!get_device(dev))
278 sdev = to_scsi_device(dev);
280 if (device_handler_match(scsi_dh, sdev))
281 scsi_dh_handler_attach(sdev, scsi_dh);
289 * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
291 static int scsi_dh_notifier_remove(struct device *dev, void *data)
293 struct scsi_device_handler *scsi_dh = data;
294 struct scsi_device *sdev;
296 if (!scsi_is_sdev_device(dev))
299 if (!get_device(dev))
302 sdev = to_scsi_device(dev);
304 scsi_dh_handler_detach(sdev, scsi_dh);
312 * scsi_register_device_handler - register a device handler personality
314 * @scsi_dh - device handler to be registered.
316 * Returns 0 on success, -EBUSY if handler already registered.
318 int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
322 if (get_device_handler(scsi_dh->name))
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);
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,
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);
344 EXPORT_SYMBOL_GPL(scsi_register_device_handler);
347 * scsi_unregister_device_handler - register a device handler personality
349 * @scsi_dh - device handler to be unregistered.
351 * Returns 0 on success, -ENODEV if handler not registered.
353 int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
357 if (!get_device_handler(scsi_dh->name))
360 bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
361 scsi_dh_notifier_remove);
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,
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);
376 EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
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
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.
391 int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
395 struct scsi_device *sdev;
396 struct scsi_device_handler *scsi_dh = NULL;
398 spin_lock_irqsave(q->queue_lock, flags);
400 if (sdev && sdev->scsi_dh_data)
401 scsi_dh = sdev->scsi_dh_data->scsi_dh;
402 if (!scsi_dh || !get_device(&sdev->sdev_gendev) ||
403 sdev->sdev_state == SDEV_CANCEL ||
404 sdev->sdev_state == SDEV_DEL)
406 if (sdev->sdev_state == SDEV_OFFLINE)
407 err = SCSI_DH_DEV_OFFLINED;
408 spin_unlock_irqrestore(q->queue_lock, flags);
416 if (scsi_dh->activate)
417 err = scsi_dh->activate(sdev, fn, data);
418 put_device(&sdev->sdev_gendev);
421 EXPORT_SYMBOL_GPL(scsi_dh_activate);
424 * scsi_dh_set_params - set the parameters for the device as per the
425 * string specified in params.
426 * @q - Request queue that is associated with the scsi_device for
427 * which the parameters to be set.
428 * @params - parameters in the following format
429 * "no_of_params\0param1\0param2\0param3\0...\0"
430 * for example, string for 2 parameters with value 10 and 21
431 * is specified as "2\010\021\0".
433 int scsi_dh_set_params(struct request_queue *q, const char *params)
435 int err = -SCSI_DH_NOSYS;
437 struct scsi_device *sdev;
438 struct scsi_device_handler *scsi_dh = NULL;
440 spin_lock_irqsave(q->queue_lock, flags);
442 if (sdev && sdev->scsi_dh_data)
443 scsi_dh = sdev->scsi_dh_data->scsi_dh;
444 if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
446 spin_unlock_irqrestore(q->queue_lock, flags);
450 err = scsi_dh->set_params(sdev, params);
451 put_device(&sdev->sdev_gendev);
454 EXPORT_SYMBOL_GPL(scsi_dh_set_params);
457 * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
458 * the given name. FALSE(0) otherwise.
459 * @name - name of the device handler.
461 int scsi_dh_handler_exist(const char *name)
463 return (get_device_handler(name) != NULL);
465 EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
468 * scsi_dh_handler_attach - Attach device handler
469 * @sdev - sdev the handler should be attached to
470 * @name - name of the handler to attach
472 int scsi_dh_attach(struct request_queue *q, const char *name)
475 struct scsi_device *sdev;
476 struct scsi_device_handler *scsi_dh;
479 scsi_dh = get_device_handler(name);
483 spin_lock_irqsave(q->queue_lock, flags);
485 if (!sdev || !get_device(&sdev->sdev_gendev))
487 spin_unlock_irqrestore(q->queue_lock, flags);
490 err = scsi_dh_handler_attach(sdev, scsi_dh);
491 put_device(&sdev->sdev_gendev);
495 EXPORT_SYMBOL_GPL(scsi_dh_attach);
498 * scsi_dh_handler_detach - Detach device handler
499 * @sdev - sdev the handler should be detached from
501 * This function will detach the device handler only
502 * if the sdev is not part of the internal list, ie
503 * if it has been attached manually.
505 void scsi_dh_detach(struct request_queue *q)
508 struct scsi_device *sdev;
509 struct scsi_device_handler *scsi_dh = NULL;
511 spin_lock_irqsave(q->queue_lock, flags);
513 if (!sdev || !get_device(&sdev->sdev_gendev))
515 spin_unlock_irqrestore(q->queue_lock, flags);
520 if (sdev->scsi_dh_data) {
521 scsi_dh = sdev->scsi_dh_data->scsi_dh;
522 scsi_dh_handler_detach(sdev, scsi_dh);
524 put_device(&sdev->sdev_gendev);
526 EXPORT_SYMBOL_GPL(scsi_dh_detach);
528 static struct notifier_block scsi_dh_nb = {
529 .notifier_call = scsi_dh_notifier
532 static int __init scsi_dh_init(void)
536 r = scsi_dev_info_add_list(SCSI_DEVINFO_DH, "SCSI Device Handler");
540 r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
543 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
544 scsi_dh_sysfs_attr_add);
549 static void __exit scsi_dh_exit(void)
551 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
552 scsi_dh_sysfs_attr_remove);
553 bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
554 scsi_dev_info_remove_list(SCSI_DEVINFO_DH);
557 module_init(scsi_dh_init);
558 module_exit(scsi_dh_exit);
560 MODULE_DESCRIPTION("SCSI device handler");
561 MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
562 MODULE_LICENSE("GPL");