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
 157                         kref_get(&sdev->scsi_dh_data->kref);
 158         } else if (scsi_dh->attach) {
 159                 err = scsi_dh->attach(sdev);
 160                 if (!err) {
 161                         kref_init(&sdev->scsi_dh_data->kref);
 162                         sdev->scsi_dh_data->sdev = sdev;
 163                 }
 164         }
 165         return err;
 166 }
 167
 168 static void __detach_handler (struct kref *kref)
 169 {
 170         struct scsi_dh_data *scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
 171         scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev);
 172 }
 173
 174 /*
 175  * scsi_dh_handler_detach - Detach a device handler from a device
 176  * @sdev - SCSI device the device handler should be detached from
 177  * @scsi_dh - Device handler to be detached
 178  *
 179  * Detach from a device handler. If a device handler is specified,
 180  * only detach if the currently attached handler matches @scsi_dh.
 181  */
 182 static void scsi_dh_handler_detach(struct scsi_device *sdev,
 183                                    struct scsi_device_handler *scsi_dh)
 184 {
 185         if (!sdev->scsi_dh_data)
 186                 return;
 187
 188         if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
 189                 return;
 190
 191         if (!scsi_dh)
 192                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 193
 194         if (scsi_dh && scsi_dh->detach)
 195                 kref_put(&sdev->scsi_dh_data->kref, __detach_handler);
 196 }
 197
 198 /*
 199  * Functions for sysfs attribute 'dh_state'
 200  */
 201 static ssize_t
 202 store_dh_state(struct device *dev, struct device_attribute *attr,
 203                const char *buf, size_t count)
 204 {
 205         struct scsi_device *sdev = to_scsi_device(dev);
 206         struct scsi_device_handler *scsi_dh;
 207         int err = -EINVAL;
 208
 209         if (!sdev->scsi_dh_data) {
 210                 /*
 211                  * Attach to a device handler
 212                  */
 213                 if (!(scsi_dh = get_device_handler(buf)))
 214                         return err;
 215                 err = scsi_dh_handler_attach(sdev, scsi_dh);
 216         } else {
 217                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 218                 if (!strncmp(buf, "detach", 6)) {
 219                         /*
 220                          * Detach from a device handler
 221                          */
 222                         scsi_dh_handler_detach(sdev, scsi_dh);
 223                         err = 0;
 224                 } else if (!strncmp(buf, "activate", 8)) {
 225                         /*
 226                          * Activate a device handler
 227                          */
 228                         if (scsi_dh->activate)
 229                                 err = scsi_dh->activate(sdev);
 230                         else
 231                                 err = 0;
 232                 }
 233         }
 234
 235         return err<0?err:count;
 236 }
 237
 238 static ssize_t
 239 show_dh_state(struct device *dev, struct device_attribute *attr, char *buf)
 240 {
 241         struct scsi_device *sdev = to_scsi_device(dev);
 242
 243         if (!sdev->scsi_dh_data)
 244                 return snprintf(buf, 20, "detached\n");
 245
 246         return snprintf(buf, 20, "%s\n", sdev->scsi_dh_data->scsi_dh->name);
 247 }
 248
 249 static struct device_attribute scsi_dh_state_attr =
 250         __ATTR(dh_state, S_IRUGO | S_IWUSR, show_dh_state,
 251                store_dh_state);
 252
 253 /*
 254  * scsi_dh_sysfs_attr_add - Callback for scsi_init_dh
 255  */
 256 static int scsi_dh_sysfs_attr_add(struct device *dev, void *data)
 257 {
 258         struct scsi_device *sdev;
 259         int err;
 260
 261         if (!scsi_is_sdev_device(dev))
 262                 return 0;
 263
 264         sdev = to_scsi_device(dev);
 265
 266         err = device_create_file(&sdev->sdev_gendev,
 267                                  &scsi_dh_state_attr);
 268
 269         return 0;
 270 }
 271
 272 /*
 273  * scsi_dh_sysfs_attr_remove - Callback for scsi_exit_dh
 274  */
 275 static int scsi_dh_sysfs_attr_remove(struct device *dev, void *data)
 276 {
 277         struct scsi_device *sdev;
 278
 279         if (!scsi_is_sdev_device(dev))
 280                 return 0;
 281
 282         sdev = to_scsi_device(dev);
 283
 284         device_remove_file(&sdev->sdev_gendev,
 285                            &scsi_dh_state_attr);
 286
 287         return 0;
 288 }
 289
 290 /*
 291  * scsi_dh_notifier - notifier chain callback
 292  */
 293 static int scsi_dh_notifier(struct notifier_block *nb,
 294                             unsigned long action, void *data)
 295 {
 296         struct device *dev = data;
 297         struct scsi_device *sdev;
 298         int err = 0;
 299         struct scsi_device_handler *devinfo = NULL;
 300
 301         if (!scsi_is_sdev_device(dev))
 302                 return 0;
 303
 304         sdev = to_scsi_device(dev);
 305
 306         if (action == BUS_NOTIFY_ADD_DEVICE) {
 307                 err = device_create_file(dev, &scsi_dh_state_attr);
 308                 /* don't care about err */
 309                 devinfo = device_handler_match(NULL, sdev);
 310                 if (devinfo)
 311                         err = scsi_dh_handler_attach(sdev, devinfo);
 312         } else if (action == BUS_NOTIFY_DEL_DEVICE) {
 313                 device_remove_file(dev, &scsi_dh_state_attr);
 314                 scsi_dh_handler_detach(sdev, NULL);
 315         }
 316         return err;
 317 }
 318
 319 /*
 320  * scsi_dh_notifier_add - Callback for scsi_register_device_handler
 321  */
 322 static int scsi_dh_notifier_add(struct device *dev, void *data)
 323 {
 324         struct scsi_device_handler *scsi_dh = data;
 325         struct scsi_device *sdev;
 326
 327         if (!scsi_is_sdev_device(dev))
 328                 return 0;
 329
 330         if (!get_device(dev))
 331                 return 0;
 332
 333         sdev = to_scsi_device(dev);
 334
 335         if (device_handler_match(scsi_dh, sdev))
 336                 scsi_dh_handler_attach(sdev, scsi_dh);
 337
 338         put_device(dev);
 339
 340         return 0;
 341 }
 342
 343 /*
 344  * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
 345  */
 346 static int scsi_dh_notifier_remove(struct device *dev, void *data)
 347 {
 348         struct scsi_device_handler *scsi_dh = data;
 349         struct scsi_device *sdev;
 350
 351         if (!scsi_is_sdev_device(dev))
 352                 return 0;
 353
 354         if (!get_device(dev))
 355                 return 0;
 356
 357         sdev = to_scsi_device(dev);
 358
 359         scsi_dh_handler_detach(sdev, scsi_dh);
 360
 361         put_device(dev);
 362
 363         return 0;
 364 }
 365
 366 /*
 367  * scsi_register_device_handler - register a device handler personality
 368  *      module.
 369  * @scsi_dh - device handler to be registered.
 370  *
 371  * Returns 0 on success, -EBUSY if handler already registered.
 372  */
 373 int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
 374 {
 375         if (get_device_handler(scsi_dh->name))
 376                 return -EBUSY;
 377
 378         spin_lock(&list_lock);
 379         list_add(&scsi_dh->list, &scsi_dh_list);
 380         spin_unlock(&list_lock);
 381         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
 382         printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
 383
 384         return SCSI_DH_OK;
 385 }
 386 EXPORT_SYMBOL_GPL(scsi_register_device_handler);
 387
 388 /*
 389  * scsi_unregister_device_handler - register a device handler personality
 390  *      module.
 391  * @scsi_dh - device handler to be unregistered.
 392  *
 393  * Returns 0 on success, -ENODEV if handler not registered.
 394  */
 395 int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
 396 {
 397         struct scsi_dh_devinfo_list *tmp, *pos;
 398
 399         if (!get_device_handler(scsi_dh->name))
 400                 return -ENODEV;
 401
 402         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
 403                          scsi_dh_notifier_remove);
 404
 405         spin_lock(&list_lock);
 406         list_del(&scsi_dh->list);
 407         list_for_each_entry_safe(pos, tmp, &scsi_dh_dev_list, node) {
 408                 if (pos->handler == scsi_dh) {
 409                         list_del(&pos->node);
 410                         kfree(pos);
 411                 }
 412         }
 413         spin_unlock(&list_lock);
 414         printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
 415
 416         return SCSI_DH_OK;
 417 }
 418 EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
 419
 420 /*
 421  * scsi_dh_activate - activate the path associated with the scsi_device
 422  *      corresponding to the given request queue.
 423  * @q - Request queue that is associated with the scsi_device to be
 424  *      activated.
 425  */
 426 int scsi_dh_activate(struct request_queue *q)
 427 {
 428         int err = 0;
 429         unsigned long flags;
 430         struct scsi_device *sdev;
 431         struct scsi_device_handler *scsi_dh = NULL;
 432
 433         spin_lock_irqsave(q->queue_lock, flags);
 434         sdev = q->queuedata;
 435         if (!sdev) {
 436                 spin_unlock_irqrestore(q->queue_lock, flags);
 437                 return SCSI_DH_NOSYS;
 438         }
 439
 440         if (sdev->scsi_dh_data)
 441                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 442         if (!scsi_dh || !get_device(&sdev->sdev_gendev))
 443                 err = SCSI_DH_NOSYS;
 444         spin_unlock_irqrestore(q->queue_lock, flags);
 445
 446         if (err)
 447                 return err;
 448
 449         if (scsi_dh->activate)
 450                 err = scsi_dh->activate(sdev);
 451         put_device(&sdev->sdev_gendev);
 452         return err;
 453 }
 454 EXPORT_SYMBOL_GPL(scsi_dh_activate);
 455
 456 /*
 457  * scsi_dh_set_params - set the parameters for the device as per the
 458  *      string specified in params.
 459  * @q - Request queue that is associated with the scsi_device for
 460  *      which the parameters to be set.
 461  * @params - parameters in the following format
 462  *      "no_of_params\0param1\0param2\0param3\0...\0"
 463  *      for example, string for 2 parameters with value 10 and 21
 464  *      is specified as "2\010\021\0".
 465  */
 466 int scsi_dh_set_params(struct request_queue *q, const char *params)
 467 {
 468         int err = -SCSI_DH_NOSYS;
 469         unsigned long flags;
 470         struct scsi_device *sdev;
 471         struct scsi_device_handler *scsi_dh = NULL;
 472
 473         spin_lock_irqsave(q->queue_lock, flags);
 474         sdev = q->queuedata;
 475         if (sdev && sdev->scsi_dh_data)
 476                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 477         if (scsi_dh && scsi_dh->set_params && get_device(&sdev->sdev_gendev))
 478                 err = 0;
 479         spin_unlock_irqrestore(q->queue_lock, flags);
 480
 481         if (err)
 482                 return err;
 483         err = scsi_dh->set_params(sdev, params);
 484         put_device(&sdev->sdev_gendev);
 485         return err;
 486 }
 487 EXPORT_SYMBOL_GPL(scsi_dh_set_params);
 488
 489 /*
 490  * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for
 491  *      the given name. FALSE(0) otherwise.
 492  * @name - name of the device handler.
 493  */
 494 int scsi_dh_handler_exist(const char *name)
 495 {
 496         return (get_device_handler(name) != NULL);
 497 }
 498 EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
 499
 500 /*
 501  * scsi_dh_handler_attach - Attach device handler
 502  * @sdev - sdev the handler should be attached to
 503  * @name - name of the handler to attach
 504  */
 505 int scsi_dh_attach(struct request_queue *q, const char *name)
 506 {
 507         unsigned long flags;
 508         struct scsi_device *sdev;
 509         struct scsi_device_handler *scsi_dh;
 510         int err = 0;
 511
 512         scsi_dh = get_device_handler(name);
 513         if (!scsi_dh)
 514                 return -EINVAL;
 515
 516         spin_lock_irqsave(q->queue_lock, flags);
 517         sdev = q->queuedata;
 518         if (!sdev || !get_device(&sdev->sdev_gendev))
 519                 err = -ENODEV;
 520         spin_unlock_irqrestore(q->queue_lock, flags);
 521
 522         if (!err) {
 523                 err = scsi_dh_handler_attach(sdev, scsi_dh);
 524                 put_device(&sdev->sdev_gendev);
 525         }
 526         return err;
 527 }
 528 EXPORT_SYMBOL_GPL(scsi_dh_attach);
 529
 530 /*
 531  * scsi_dh_handler_detach - Detach device handler
 532  * @sdev - sdev the handler should be detached from
 533  *
 534  * This function will detach the device handler only
 535  * if the sdev is not part of the internal list, ie
 536  * if it has been attached manually.
 537  */
 538 void scsi_dh_detach(struct request_queue *q)
 539 {
 540         unsigned long flags;
 541         struct scsi_device *sdev;
 542         struct scsi_device_handler *scsi_dh = NULL;
 543
 544         spin_lock_irqsave(q->queue_lock, flags);
 545         sdev = q->queuedata;
 546         if (!sdev || !get_device(&sdev->sdev_gendev))
 547                 sdev = NULL;
 548         spin_unlock_irqrestore(q->queue_lock, flags);
 549
 550         if (!sdev)
 551                 return;
 552
 553         if (sdev->scsi_dh_data) {
 554                 scsi_dh = sdev->scsi_dh_data->scsi_dh;
 555                 scsi_dh_handler_detach(sdev, scsi_dh);
 556         }
 557         put_device(&sdev->sdev_gendev);
 558 }
 559 EXPORT_SYMBOL_GPL(scsi_dh_detach);
 560
 561 static struct notifier_block scsi_dh_nb = {
 562         .notifier_call = scsi_dh_notifier
 563 };
 564
 565 static int __init scsi_dh_init(void)
 566 {
 567         int r;
 568
 569         r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
 570
 571         if (!r)
 572                 bus_for_each_dev(&scsi_bus_type, NULL, NULL,
 573                                  scsi_dh_sysfs_attr_add);
 574
 575         return r;
 576 }
 577
 578 static void __exit scsi_dh_exit(void)
 579 {
 580         bus_for_each_dev(&scsi_bus_type, NULL, NULL,
 581                          scsi_dh_sysfs_attr_remove);
 582         bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
 583 }
 584
 585 module_init(scsi_dh_init);
 586 module_exit(scsi_dh_exit);
 587
 588 MODULE_DESCRIPTION("SCSI device handler");
 589 MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
 590 MODULE_LICENSE("GPL");