drivers/scsi/device_handler/scsi_dh.c

   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 <scsi/scsi_dh.h>
  25 #include "../scsi_priv.h"
  26
  27 struct scsi_dh_devinfo_list {
  28         struct list_head node;
  29         char vendor[9];
  30         char model[17];
  31         struct scsi_device_handler *handler;
  32 };
  33
  34 static DEFINE_SPINLOCK(list_lock);
  35 static LIST_HEAD(scsi_dh_list);
  36 static LIST_HEAD(scsi_dh_dev_list);
  37
  38 static struct scsi_device_handler *get_device_handler(const char *name)
  39 {
  40         struct scsi_device_handler *tmp, *found = NULL;
  41
  42         spin_lock(&list_lock);
  43         list_for_each_entry(tmp, &scsi_dh_list, list) {
  44                 if (!strncmp(tmp->name, name, strlen(tmp->name))) {
  45                         found = tmp;
  46                         break;
  47                 }
  48         }
  49         spin_unlock(&list_lock);
  50         return found;
  51 }
  52
  53
  54 static struct scsi_device_handler *
  55 scsi_dh_cache_lookup(struct scsi_device *sdev)
  56 {
  57         struct scsi_dh_devinfo_list *tmp;
  58         struct scsi_device_handler *found_dh = NULL;
  59
  60         spin_lock(&list_lock);
  61         list_for_each_entry(tmp, &scsi_dh_dev_list, node) {
  62                 if (!strncmp(sdev->vendor, tmp->vendor, strlen(tmp->vendor)) &&
  63                     !strncmp(sdev->model, tmp->model, strlen(tmp->model))) {
  64                         found_dh = tmp->handler;
  65                         break;
  66                 }
  67         }
  68         spin_unlock(&list_lock);
  69
  70         return found_dh;
  71 }
  72
  73 static int scsi_dh_handler_lookup(struct scsi_device_handler *scsi_dh,
  74                                   struct scsi_device *sdev)
  75 {
  76         int i, found = 0;
  77
  78         for(i = 0; scsi_dh->devlist[i].vendor; i++) {
  79                 if (!strncmp(sdev->vendor, scsi_dh->devlist[i].vendor,
  80                              strlen(scsi_dh->devlist[i].vendor)) &&
  81                     !strncmp(sdev->model, scsi_dh->devlist[i].model,
  82                              strlen(scsi_dh->devlist[i].model))) {
  83                         found = 1;
  84                         break;
  85                 }
  86         }
  87         return found;
  88 }
  89
  90 /*
  91  * device_handler_match - Attach a device handler to a device
  92  * @scsi_dh - The device handler to match against or NULL
  93  * @sdev - SCSI device to be tested against @scsi_dh
  94  *
  95  * Tests @sdev against the device handler @scsi_dh or against
  96  * all registered device_handler if @scsi_dh == NULL.
  97  * Returns the found device handler or NULL if not found.
  98  */
  99 static struct scsi_device_handler *
 100 device_handler_match(struct scsi_device_handler *scsi_dh,
 101                      struct scsi_device *sdev)
 102 {
 103         struct scsi_device_handler *found_dh = NULL;
 104         struct scsi_dh_devinfo_list *tmp;
 105
 106         found_dh = scsi_dh_cache_lookup(sdev);
 107         if (found_dh)
 108                 return found_dh;
 109
 110         if (scsi_dh) {
 111                 if (scsi_dh_handler_lookup(scsi_dh, sdev))
 112                         found_dh = scsi_dh;
 113         } else {
 114                 struct scsi_device_handler *tmp_dh;
 115
 116                 spin_lock(&list_lock);
 117                 list_for_each_entry(tmp_dh, &scsi_dh_list, list) {
 118                         if (scsi_dh_handler_lookup(tmp_dh, sdev))
 119                                 found_dh = tmp_dh;
 120                 }
 121                 spin_unlock(&list_lock);
 122         }
 123
 124         if (found_dh) { /* If device is found, add it to the cache */
 125                 tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
 126                 if (tmp) {
 127                         strncpy(tmp->vendor, sdev->vendor, 8);
 128                         strncpy(tmp->model, sdev->model, 16);
 129                         tmp->vendor[8] = '\0';
 130                         tmp->model[16] = '\0';
 131                         tmp->handler = found_dh;
 132                         spin_lock(&list_lock);
 133                         list_add(&tmp->node, &scsi_dh_dev_list);
 134                         spin_unlock(&list_lock);
 135                 } else {
 136                         found_dh = NULL;
 137                 }
 138         }
 139
 140         return found_dh;
 141 }
 142
 143 /*
 144  * scsi_dh_handler_attach - Attach a device handler to a device
 145  * @sdev - SCSI device the device handler should attach to
 146  * @scsi_dh - The device handler to attach
 147  */
 148 static int scsi_dh_handler_attach(struct scsi_device *sdev,
 149                                   struct scsi_device_handler *scsi_dh)
 150 {
 151         int err = 0;
 152
 153         if (sdev->scsi_dh_data) {
 154                 if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
 155                         err = -EBUSY;
 156         } else if (scsi_dh->attach)
 157                 err = scsi_dh->attach(sdev);
 158
 159         return err;
 160 }
 161
 162 /*
 163  * scsi_dh_handler_detach - Detach a device handler from a device
 164  * @sdev - SCSI device the device handler should be detached from
 165  * @scsi_dh - Device handler to be detached
 166  *
 167  * Detach from a device handler. If a device handler is specified,
 168  * only detach if the currently attached handler matches @scsi_dh.
 169  */
 170 static void scsi_dh_handler_detach(struct scsi_device *sdev,
 171                                    struct scsi_device_handler *scsi_dh)
 172 {
 173         if (!sdev->scsi_dh_data)
 174                 return;
 175
 176         if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
 177                 return;
 178
 179         if (!scsi_dh)
 180                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 181
 182         if (scsi_dh && scsi_dh->detach)
 183                 scsi_dh->detach(sdev);
 184 }
 185
 186 /*
 187  * Functions for sysfs attribute 'dh_state'
 188  */
 189 static ssize_t
 190 store_dh_state(struct device *dev, struct device_attribute *attr,
 191                const char *buf, size_t count)
 192 {
 193         struct scsi_device *sdev = to_scsi_device(dev);
 194         struct scsi_device_handler *scsi_dh;
 195         int err = -EINVAL;
 196
 197         if (!sdev->scsi_dh_data) {
 198                 /*
 199                  * Attach to a device handler
 200                  */
 201                 if (!(scsi_dh = get_device_handler(buf)))
 202                         return err;
 203                 err = scsi_dh_handler_attach(sdev, scsi_dh);
 204         } else {
 205                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 206                 if (!strncmp(buf, "detach", 6)) {
 207                         /*
 208                          * Detach from a device handler
 209                          */
 210                         scsi_dh_handler_detach(sdev, scsi_dh);
 211                         err = 0;
 212                 } else if (!strncmp(buf, "activate", 8)) {
 213                         /*
 214                          * Activate a device handler
 215                          */
 216                         if (scsi_dh->activate)
 217                                 err = scsi_dh->activate(sdev);
 218                         else
 219                                 err = 0;
 220                 }
 221         }
 222
 223         return err<0?err:count;
 224 }
 225
 226 static ssize_t
 227 show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
 228 {
 229         struct scsi_device *sdev = to_scsi_device(dev);
 230
 231         if (!sdev->scsi_dh_data)
 232                 return snprintf(buf, 20, "detached\n");
 233
 234         return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
 235 }
 236
 237 static struct device_attribute scsi_dh_state_attr =
 238         __ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
 239                store_dh_state);
 240
 241 /*
 242  * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
 243  */
 244 static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
 245 {
 246         struct scsi_device *sdev;
 247         int err;
 248
 249         if (!scsi_is_sdev_device(dev))
 250                 return 0;
 251
 252         sdev = to_scsi_device(dev);
 253
 254         err = device_create_file(&sdev->sdev_gendev,
 255                                  &scsi_dh_state_attr);
 256
 257         return 0;
 258 }
 259
 260 /*
 261  * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
 262  */
 263 static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
 264 {
 265         struct scsi_device *sdev;
 266
 267         if (!scsi_is_sdev_device(dev))
 268                 return 0;
 269
 270         sdev = to_scsi_device(dev);
 271
 272         device_remove_file(&sdev->sdev_gendev,
 273                            &scsi_dh_state_attr);
 274
 275         return 0;
 276 }
 277
 278 /*
 279  * scsi_dh_notifier - notifier chain callback
 280  */
 281 static int scsi_dh_notifier(struct notifier_block *nb,
 282                             unsigned long action, void *data)
 283 {
 284         struct device *dev = data;
 285         struct scsi_device *sdev;
 286         int err = 0;
 287         struct scsi_device_handler *devinfo = NULL;
 288
 289         if (!scsi_is_sdev_device(dev))
 290                 return 0;
 291
 292         sdev = to_scsi_device(dev);
 293
 294         if (action == BUS_NOTIFY_ADD_DEVICE) {
 295                 devinfo = device_handler_match(NULL, sdev);
 296                 if (!devinfo)
 297                         goto out;
 298
 299                 err = scsi_dh_handler_attach(sdev, devinfo);
 300                 if (!err)
 301                         err = device_create_file(dev, &scsi_dh_state_attr);
 302         } else if (action == BUS_NOTIFY_DEL_DEVICE) {
 303                 device_remove_file(dev, &scsi_dh_state_attr);
 304                 scsi_dh_handler_detach(sdev, NULL);
 305         }
 306 out:
 307         return err;
 308 }
 309
 310 /*
 311  * scsi_dh_notifier_add - Callback for scsi_register_device_handler
 312  */
 313 static int scsi_dh_notifier_add(struct device *dev, void *data)
 314 {
 315         struct scsi_device_handler *scsi_dh = data;
 316         struct scsi_device *sdev;
 317
 318         if (!scsi_is_sdev_device(dev))
 319                 return 0;
 320
 321         if (!get_device(dev))
 322                 return 0;
 323
 324         sdev = to_scsi_device(dev);
 325
 326         if (device_handler_match(scsi_dh, sdev))
 327                 scsi_dh_handler_attach(sdev, scsi_dh);
 328
 329         put_device(dev);
 330
 331         return 0;
 332 }
 333
 334 /*
 335  * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
 336  */
 337 static int scsi_dh_notifier_remove(struct device *dev, void *data)
 338 {
 339         struct scsi_device_handler *scsi_dh = data;
 340         struct scsi_device *sdev;
 341
 342         if (!scsi_is_sdev_device(dev))
 343                 return 0;
 344
 345         if (!get_device(dev))
 346                 return 0;
 347
 348         sdev = to_scsi_device(dev);
 349
 350         scsi_dh_handler_detach(sdev, scsi_dh);
 351
 352         put_device(dev);
 353
 354         return 0;
 355 }
 356
 357 /*
 358  * scsi_register_device_handler - register a device handler personality
 359  *      module.
 360  * @scsi_dh - device handler to be registered.
 361  *
 362  * Returns 0 on success, -EBUSY if handler already registered.
 363  */
 364 int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
 365 {
 366         if (get_device_handler(scsi_dh->name))
 367                 return -EBUSY;
 368
 369         spin_lock(&list_lock);
 370         list_add(&scsi_dh->list, &scsi_dh_list);
 371         spin_unlock(&list_lock);
 372         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
 373         printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
 374
 375         return SCSI_DH_OK;
 376 }
 377 EXPORT_SYMBOL_GPL(scsi_register_device_handler);
 378
 379 /*
 380  * scsi_unregister_device_handler - register a device handler personality
 381  *      module.
 382  * @scsi_dh - device handler to be unregistered.
 383  *
 384  * Returns 0 on success, -ENODEV if handler not registered.
 385  */
 386 int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
 387 {
 388         struct scsi_dh_devinfo_list *tmp, *pos;
 389
 390         if (!get_device_handler(scsi_dh->name))
 391                 return -ENODEV;
 392
 393         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
 394                          scsi_dh_notifier_remove);
 395
 396         spin_lock(&list_lock);
 397         list_del(&scsi_dh->list);
 398         list_for_each_entry_safe(pos, tmp, &scsi_dh_dev_list, node) {
 399                 if (pos->handler == scsi_dh) {
 400                         list_del(&pos->node);
 401                         kfree(pos);
 402                 }
 403         }
 404         spin_unlock(&list_lock);
 405         printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
 406
 407         return SCSI_DH_OK;
 408 }
 409 EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
 410
 411 /*
 412  * scsi_dh_activate - activate the path associated with the scsi_device
 413  *      corresponding to the given request queue.
 414  * @q - Request queue that is associated with the scsi_device to be
 415  *      activated.
 416  */
 417 int scsi_dh_activate(struct request_queue *q)
 418 {
 419         int err = 0;
 420         unsigned long flags;
 421         struct scsi_device *sdev;
 422         struct scsi_device_handler *scsi_dh = NULL;
 423
 424         spin_lock_irqsave(q->queue_lock, flags);
 425         sdev = q->queuedata;
 426         if (sdev && sdev->scsi_dh_data)
 427                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 428         if (!scsi_dh || !get_device(&sdev->sdev_gendev))
 429                 err = SCSI_DH_NOSYS;
 430         spin_unlock_irqrestore(q->queue_lock, flags);
 431
 432         if (err)
 433                 return err;
 434
 435         if (scsi_dh->activate)
 436                 err = scsi_dh->activate(sdev);
 437         put_device(&sdev->sdev_gendev);
 438         return err;
 439 }
 440 EXPORT_SYMBOL_GPL(scsi_dh_activate);
 441
 442 /*
 443  * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
 444  *      the given name. FALSE(0) otherwise.
 445  * @name - name of the device handler.
 446  */
 447 int scsi_dh_handler_exist(const char *name)
 448 {
 449         return (get_device_handler(name) != NULL);
 450 }
 451 EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
 452
 453 /*
 454  * scsi_dh_handler_attach - Attach device handler
 455  * @sdev - sdev the handler should be attached to
 456  * @name - name of the handler to attach
 457  */
 458 int scsi_dh_attach(struct request_queue *q, const char *name)
 459 {
 460         unsigned long flags;
 461         struct scsi_device *sdev;
 462         struct scsi_device_handler *scsi_dh;
 463         int err = 0;
 464
 465         scsi_dh = get_device_handler(name);
 466         if (!scsi_dh)
 467                 return -EINVAL;
 468
 469         spin_lock_irqsave(q->queue_lock, flags);
 470         sdev = q->queuedata;
 471         if (!sdev || !get_device(&sdev->sdev_gendev))
 472                 err = -ENODEV;
 473         spin_unlock_irqrestore(q->queue_lock, flags);
 474
 475         if (!err) {
 476                 err = scsi_dh_handler_attach(sdev, scsi_dh);
 477
 478                 put_device(&sdev->sdev_gendev);
 479         }
 480         return err;
 481 }
 482 EXPORT_SYMBOL_GPL(scsi_dh_attach);
 483
 484 /*
 485  * scsi_dh_handler_detach - Detach device handler
 486  * @sdev - sdev the handler should be detached from
 487  *
 488  * This function will detach the device handler only
 489  * if the sdev is not part of the internal list, ie
 490  * if it has been attached manually.
 491  */
 492 void scsi_dh_detach(struct request_queue *q)
 493 {
 494         unsigned long flags;
 495         struct scsi_device *sdev;
 496         struct scsi_device_handler *scsi_dh = NULL;
 497
 498         spin_lock_irqsave(q->queue_lock, flags);
 499         sdev = q->queuedata;
 500         if (!sdev || !get_device(&sdev->sdev_gendev))
 501                 sdev = NULL;
 502         spin_unlock_irqrestore(q->queue_lock, flags);
 503
 504         if (!sdev)
 505                 return;
 506
 507         if (sdev->scsi_dh_data) {
 508                 /* if sdev is not on internal list, detach */
 509                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 510                 if (!device_handler_match(scsi_dh, sdev))
 511                         scsi_dh_handler_detach(sdev, scsi_dh);
 512         }
 513         put_device(&sdev->sdev_gendev);
 514 }
 515 EXPORT_SYMBOL_GPL(scsi_dh_detach);
 516
 517 static struct notifier_block scsi_dh_nb = {
 518         .notifier_call = scsi_dh_notifier
 519 };
 520
 521 static int __init scsi_dh_init(void)
 522 {
 523         int r;
 524
 525         r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
 526
 527         if (!r)
 528                 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
 529                                  scsi_dh_sysfs_attr_add);
 530
 531         return r;
 532 }
 533
 534 static void __exit scsi_dh_exit(void)
 535 {
 536         bus_for_each_dev(&scsi_bus_type, NULL, NULL,
 537                          scsi_dh_sysfs_attr_remove);
 538         bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
 539 }
 540
 541 module_init(scsi_dh_init);
 542 module_exit(scsi_dh_exit);
 543
 544 MODULE_DESCRIPTION("SCSI device handler");
 545 MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
 546 MODULE_LICENSE("GPL");