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 <linux/slab.h>
  25 #include <scsi/scsi_dh.h>
  26 #include "../scsi_priv.h"
  27
  28 struct scsi_dh_devinfo_list {
  29         struct list_head node;
  30         char vendor[9];
  31         char model[17];
  32         struct scsi_device_handler *handler;
  33 };
  34
  35 static DEFINE_SPINLOCK(list_lock);
  36 static LIST_HEAD(scsi_dh_list);
  37 static LIST_HEAD(scsi_dh_dev_list);
  38
  39 static struct scsi_device_handler *get_device_handler(const char *name)
  40 {
  41         struct scsi_device_handler *tmp, *found = NULL;
  42
  43         spin_lock(&list_lock);
  44         list_for_each_entry(tmp, &scsi_dh_list, list) {
  45                 if (!strncmp(tmp->name, name, strlen(tmp->name))) {
  46                         found = tmp;
  47                         break;
  48                 }
  49         }
  50         spin_unlock(&list_lock);
  51         return found;
  52 }
  53
  54
  55 static struct scsi_device_handler *
  56 scsi_dh_cache_lookup(struct scsi_device *sdev)
  57 {
  58         struct scsi_dh_devinfo_list *tmp;
  59         struct scsi_device_handler *found_dh = NULL;
  60
  61         spin_lock(&list_lock);
  62         list_for_each_entry(tmp, &scsi_dh_dev_list, node) {
  63                 if (!strncmp(sdev->vendor, tmp->vendor, strlen(tmp->vendor)) &&
  64                     !strncmp(sdev->model, tmp->model, strlen(tmp->model))) {
  65                         found_dh = tmp->handler;
  66                         break;
  67                 }
  68         }
  69         spin_unlock(&list_lock);
  70
  71         return found_dh;
  72 }
  73
  74 static int scsi_dh_handler_lookup(struct scsi_device_handler *scsi_dh,
  75                                   struct scsi_device *sdev)
  76 {
  77         int i, found = 0;
  78
  79         for(i = 0; scsi_dh->devlist[i].vendor; i++) {
  80                 if (!strncmp(sdev->vendor, scsi_dh->devlist[i].vendor,
  81                              strlen(scsi_dh->devlist[i].vendor)) &&
  82                     !strncmp(sdev->model, scsi_dh->devlist[i].model,
  83                              strlen(scsi_dh->devlist[i].model))) {
  84                         found = 1;
  85                         break;
  86                 }
  87         }
  88         return found;
  89 }
  90
  91 /*
  92  * device_handler_match - Attach a device handler to a device
  93  * @scsi_dh - The device handler to match against or NULL
  94  * @sdev - SCSI device to be tested against @scsi_dh
  95  *
  96  * Tests @sdev against the device handler @scsi_dh or against
  97  * all registered device_handler if @scsi_dh == NULL.
  98  * Returns the found device handler or NULL if not found.
  99  */
 100 static struct scsi_device_handler *
 101 device_handler_match(struct scsi_device_handler *scsi_dh,
 102                      struct scsi_device *sdev)
 103 {
 104         struct scsi_device_handler *found_dh = NULL;
 105         struct scsi_dh_devinfo_list *tmp;
 106
 107         found_dh = scsi_dh_cache_lookup(sdev);
 108         if (found_dh)
 109                 return found_dh;
 110
 111         if (scsi_dh) {
 112                 if (scsi_dh_handler_lookup(scsi_dh, sdev))
 113                         found_dh = scsi_dh;
 114         } else {
 115                 struct scsi_device_handler *tmp_dh;
 116
 117                 spin_lock(&list_lock);
 118                 list_for_each_entry(tmp_dh, &scsi_dh_list, list) {
 119                         if (scsi_dh_handler_lookup(tmp_dh, sdev))
 120                                 found_dh = tmp_dh;
 121                 }
 122                 spin_unlock(&list_lock);
 123         }
 124
 125         if (found_dh) { /* If device is found, add it to the cache */
 126                 tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
 127                 if (tmp) {
 128                         strncpy(tmp->vendor, sdev->vendor, 8);
 129                         strncpy(tmp->model, sdev->model, 16);
 130                         tmp->vendor[8] = '\0';
 131                         tmp->model[16] = '\0';
 132                         tmp->handler = found_dh;
 133                         spin_lock(&list_lock);
 134                         list_add(&tmp->node, &scsi_dh_dev_list);
 135                         spin_unlock(&list_lock);
 136                 } else {
 137                         found_dh = NULL;
 138                 }
 139         }
 140
 141         return found_dh;
 142 }
 143
 144 /*
 145  * scsi_dh_handler_attach - Attach a device handler to a device
 146  * @sdev - SCSI device the device handler should attach to
 147  * @scsi_dh - The device handler to attach
 148  */
 149 static int scsi_dh_handler_attach(struct scsi_device *sdev,
 150                                   struct scsi_device_handler *scsi_dh)
 151 {
 152         int err = 0;
 153
 154         if (sdev->scsi_dh_data) {
 155                 if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
 156                         err = -EBUSY;
 157                 else
 158                         kref_get(&sdev->scsi_dh_data->kref);
 159         } else if (scsi_dh->attach) {
 160                 err = scsi_dh->attach(sdev);
 161                 if (!err) {
 162                         kref_init(&sdev->scsi_dh_data->kref);
 163                         sdev->scsi_dh_data->sdev = sdev;
 164                 }
 165         }
 166         return err;
 167 }
 168
 169 static void __detach_handler (struct kref *kref)
 170 {
 171         struct scsi_dh_data *scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
 172         scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev);
 173 }
 174
 175 /*
 176  * scsi_dh_handler_detach - Detach a device handler from a device
 177  * @sdev - SCSI device the device handler should be detached from
 178  * @scsi_dh - Device handler to be detached
 179  *
 180  * Detach from a device handler. If a device handler is specified,
 181  * only detach if the currently attached handler matches @scsi_dh.
 182  */
 183 static void scsi_dh_handler_detach(struct scsi_device *sdev,
 184                                    struct scsi_device_handler *scsi_dh)
 185 {
 186         if (!sdev->scsi_dh_data)
 187                 return;
 188
 189         if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
 190                 return;
 191
 192         if (!scsi_dh)
 193                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 194
 195         if (scsi_dh && scsi_dh->detach)
 196                 kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
 197 }
 198
 199 /*
 200  * Functions for sysfs attribute 'dh_state'
 201  */
 202 static ssize_t
 203 store_dh_state(struct device *dev, struct device_attribute *attr,
 204                const char *buf, size_t count)
 205 {
 206         struct scsi_device *sdev = to_scsi_device(dev);
 207         struct scsi_device_handler *scsi_dh;
 208         int err = -EINVAL;
 209
 210         if (!sdev->scsi_dh_data) {
 211                 /*
 212                  * Attach to a device handler
 213                  */
 214                 if (!(scsi_dh = get_device_handler(buf)))
 215                         return err;
 216                 err = scsi_dh_handler_attach(sdev, scsi_dh);
 217         } else {
 218                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 219                 if (!strncmp(buf, "detach", 6)) {
 220                         /*
 221                          * Detach from a device handler
 222                          */
 223                         scsi_dh_handler_detach(sdev, scsi_dh);
 224                         err = 0;
 225                 } else if (!strncmp(buf, "activate", 8)) {
 226                         /*
 227                          * Activate a device handler
 228                          */
 229                         if (scsi_dh->activate)
 230                                 err = scsi_dh->activate(sdev, NULL, NULL);
 231                         else
 232                                 err = 0;
 233                 }
 234         }
 235
 236         return err<0?err:count;
 237 }
 238
 239 static ssize_t
 240 show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
 241 {
 242         struct scsi_device *sdev = to_scsi_device(dev);
 243
 244         if (!sdev->scsi_dh_data)
 245                 return snprintf(buf, 20, "detached\n");
 246
 247         return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
 248 }
 249
 250 static struct device_attribute scsi_dh_state_attr =
 251         __ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
 252                store_dh_state);
 253
 254 /*
 255  * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
 256  */
 257 static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
 258 {
 259         struct scsi_device *sdev;
 260         int err;
 261
 262         if (!scsi_is_sdev_device(dev))
 263                 return 0;
 264
 265         sdev = to_scsi_device(dev);
 266
 267         err = device_create_file(&sdev->sdev_gendev,
 268                                  &scsi_dh_state_attr);
 269
 270         return 0;
 271 }
 272
 273 /*
 274  * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
 275  */
 276 static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
 277 {
 278         struct scsi_device *sdev;
 279
 280         if (!scsi_is_sdev_device(dev))
 281                 return 0;
 282
 283         sdev = to_scsi_device(dev);
 284
 285         device_remove_file(&sdev->sdev_gendev,
 286                            &scsi_dh_state_attr);
 287
 288         return 0;
 289 }
 290
 291 /*
 292  * scsi_dh_notifier - notifier chain callback
 293  */
 294 static int scsi_dh_notifier(struct notifier_block *nb,
 295                             unsigned long action, void *data)
 296 {
 297         struct device *dev = data;
 298         struct scsi_device *sdev;
 299         int err = 0;
 300         struct scsi_device_handler *devinfo = NULL;
 301
 302         if (!scsi_is_sdev_device(dev))
 303                 return 0;
 304
 305         sdev = to_scsi_device(dev);
 306
 307         if (action == BUS_NOTIFY_ADD_DEVICE) {
 308                 err = device_create_file(dev, &scsi_dh_state_attr);
 309                 /* don't care about err */
 310                 devinfo = device_handler_match(NULL, sdev);
 311                 if (devinfo)
 312                         err = scsi_dh_handler_attach(sdev, devinfo);
 313         } else if (action == BUS_NOTIFY_DEL_DEVICE) {
 314                 device_remove_file(dev, &scsi_dh_state_attr);
 315                 scsi_dh_handler_detach(sdev, NULL);
 316         }
 317         return err;
 318 }
 319
 320 /*
 321  * scsi_dh_notifier_add - Callback for scsi_register_device_handler
 322  */
 323 static int scsi_dh_notifier_add(struct device *dev, void *data)
 324 {
 325         struct scsi_device_handler *scsi_dh = data;
 326         struct scsi_device *sdev;
 327
 328         if (!scsi_is_sdev_device(dev))
 329                 return 0;
 330
 331         if (!get_device(dev))
 332                 return 0;
 333
 334         sdev = to_scsi_device(dev);
 335
 336         if (device_handler_match(scsi_dh, sdev))
 337                 scsi_dh_handler_attach(sdev, scsi_dh);
 338
 339         put_device(dev);
 340
 341         return 0;
 342 }
 343
 344 /*
 345  * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
 346  */
 347 static int scsi_dh_notifier_remove(struct device *dev, void *data)
 348 {
 349         struct scsi_device_handler *scsi_dh = data;
 350         struct scsi_device *sdev;
 351
 352         if (!scsi_is_sdev_device(dev))
 353                 return 0;
 354
 355         if (!get_device(dev))
 356                 return 0;
 357
 358         sdev = to_scsi_device(dev);
 359
 360         scsi_dh_handler_detach(sdev, scsi_dh);
 361
 362         put_device(dev);
 363
 364         return 0;
 365 }
 366
 367 /*
 368  * scsi_register_device_handler - register a device handler personality
 369  *      module.
 370  * @scsi_dh - device handler to be registered.
 371  *
 372  * Returns 0 on success, -EBUSY if handler already registered.
 373  */
 374 int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
 375 {
 376         if (get_device_handler(scsi_dh->name))
 377                 return -EBUSY;
 378
 379         spin_lock(&list_lock);
 380         list_add(&scsi_dh->list, &scsi_dh_list);
 381         spin_unlock(&list_lock);
 382         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
 383         printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
 384
 385         return SCSI_DH_OK;
 386 }
 387 EXPORT_SYMBOL_GPL(scsi_register_device_handler);
 388
 389 /*
 390  * scsi_unregister_device_handler - register a device handler personality
 391  *      module.
 392  * @scsi_dh - device handler to be unregistered.
 393  *
 394  * Returns 0 on success, -ENODEV if handler not registered.
 395  */
 396 int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
 397 {
 398         struct scsi_dh_devinfo_list *tmp, *pos;
 399
 400         if (!get_device_handler(scsi_dh->name))
 401                 return -ENODEV;
 402
 403         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
 404                          scsi_dh_notifier_remove);
 405
 406         spin_lock(&list_lock);
 407         list_del(&scsi_dh->list);
 408         list_for_each_entry_safe(pos, tmp, &scsi_dh_dev_list, node) {
 409                 if (pos->handler == scsi_dh) {
 410                         list_del(&pos->node);
 411                         kfree(pos);
 412                 }
 413         }
 414         spin_unlock(&list_lock);
 415         printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
 416
 417         return SCSI_DH_OK;
 418 }
 419 EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
 420
 421 /*
 422  * scsi_dh_activate - activate the path associated with the scsi_device
 423  *      corresponding to the given request queue.
 424  *     Returns immediately without waiting for activation to be completed.
 425  * @q    - Request queue that is associated with the scsi_device to be
 426  *         activated.
 427  * @fn   - Function to be called upon completion of the activation.
 428  *         Function fn is called with data (below) and the error code.
 429  *         Function fn may be called from the same calling context. So,
 430  *         do not hold the lock in the caller which may be needed in fn.
 431  * @data - data passed to the function fn upon completion.
 432  *
 433  */
 434 int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
 435 {
 436         int err = 0;
 437         unsigned long flags;
 438         struct scsi_device *sdev;
 439         struct scsi_device_handler *scsi_dh = NULL;
 440
 441         spin_lock_irqsave(q->queue_lock, flags);
 442         sdev = q->queuedata;
 443         if (sdev && sdev->scsi_dh_data)
 444                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 445         if (!scsi_dh || !get_device(&sdev->sdev_gendev))
 446                 err = SCSI_DH_NOSYS;
 447         spin_unlock_irqrestore(q->queue_lock, flags);
 448
 449         if (err)
 450                 return err;
 451
 452         if (scsi_dh->activate)
 453                 err = scsi_dh->activate(sdev, fn, data);
 454         put_device(&sdev->sdev_gendev);
 455         return err;
 456 }
 457 EXPORT_SYMBOL_GPL(scsi_dh_activate);
 458
 459 /*
 460  * scsi_dh_set_params - set the parameters for the device as per the
 461  *      string specified in params.
 462  * @q - Request queue that is associated with the scsi_device for
 463  *      which the parameters to be set.
 464  * @params - parameters in the following format
 465  *      "no_of_params\0param1\0param2\0param3\0...\0"
 466  *      for example, string for 2 parameters with value 10 and 21
 467  *      is specified as "2\010\021\0".
 468  */
 469 int scsi_dh_set_params(struct request_queue *q, const char *params)
 470 {
 471         int err = -SCSI_DH_NOSYS;
 472         unsigned long flags;
 473         struct scsi_device *sdev;
 474         struct scsi_device_handler *scsi_dh = NULL;
 475
 476         spin_lock_irqsave(q->queue_lock, flags);
 477         sdev = q->queuedata;
 478         if (sdev && sdev->scsi_dh_data)
 479                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 480         if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
 481                 err = 0;
 482         spin_unlock_irqrestore(q->queue_lock, flags);
 483
 484         if (err)
 485                 return err;
 486         err = scsi_dh->set_params(sdev, params);
 487         put_device(&sdev->sdev_gendev);
 488         return err;
 489 }
 490 EXPORT_SYMBOL_GPL(scsi_dh_set_params);
 491
 492 /*
 493  * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
 494  *      the given name. FALSE(0) otherwise.
 495  * @name - name of the device handler.
 496  */
 497 int scsi_dh_handler_exist(const char *name)
 498 {
 499         return (get_device_handler(name) != NULL);
 500 }
 501 EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
 502
 503 /*
 504  * scsi_dh_handler_attach - Attach device handler
 505  * @sdev - sdev the handler should be attached to
 506  * @name - name of the handler to attach
 507  */
 508 int scsi_dh_attach(struct request_queue *q, const char *name)
 509 {
 510         unsigned long flags;
 511         struct scsi_device *sdev;
 512         struct scsi_device_handler *scsi_dh;
 513         int err = 0;
 514
 515         scsi_dh = get_device_handler(name);
 516         if (!scsi_dh)
 517                 return -EINVAL;
 518
 519         spin_lock_irqsave(q->queue_lock, flags);
 520         sdev = q->queuedata;
 521         if (!sdev || !get_device(&sdev->sdev_gendev))
 522                 err = -ENODEV;
 523         spin_unlock_irqrestore(q->queue_lock, flags);
 524
 525         if (!err) {
 526                 err = scsi_dh_handler_attach(sdev, scsi_dh);
 527                 put_device(&sdev->sdev_gendev);
 528         }
 529         return err;
 530 }
 531 EXPORT_SYMBOL_GPL(scsi_dh_attach);
 532
 533 /*
 534  * scsi_dh_handler_detach - Detach device handler
 535  * @sdev - sdev the handler should be detached from
 536  *
 537  * This function will detach the device handler only
 538  * if the sdev is not part of the internal list, ie
 539  * if it has been attached manually.
 540  */
 541 void scsi_dh_detach(struct request_queue *q)
 542 {
 543         unsigned long flags;
 544         struct scsi_device *sdev;
 545         struct scsi_device_handler *scsi_dh = NULL;
 546
 547         spin_lock_irqsave(q->queue_lock, flags);
 548         sdev = q->queuedata;
 549         if (!sdev || !get_device(&sdev->sdev_gendev))
 550                 sdev = NULL;
 551         spin_unlock_irqrestore(q->queue_lock, flags);
 552
 553         if (!sdev)
 554                 return;
 555
 556         if (sdev->scsi_dh_data) {
 557                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 558                 scsi_dh_handler_detach(sdev, scsi_dh);
 559         }
 560         put_device(&sdev->sdev_gendev);
 561 }
 562 EXPORT_SYMBOL_GPL(scsi_dh_detach);
 563
 564 static struct notifier_block scsi_dh_nb = {
 565         .notifier_call = scsi_dh_notifier
 566 };
 567
 568 static int __init scsi_dh_init(void)
 569 {
 570         int r;
 571
 572         r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
 573
 574         if (!r)
 575                 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
 576                                  scsi_dh_sysfs_attr_add);
 577
 578         return r;
 579 }
 580
 581 static void __exit scsi_dh_exit(void)
 582 {
 583         bus_for_each_dev(&scsi_bus_type, NULL, NULL,
 584                          scsi_dh_sysfs_attr_remove);
 585         bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
 586 }
 587
 588 module_init(scsi_dh_init);
 589 module_exit(scsi_dh_exit);
 590
 591 MODULE_DESCRIPTION("SCSI device handler");
 592 MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
 593 MODULE_LICENSE("GPL");