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   1 /*
   2  *  drivers/s390/cio/css.c
   3  *  driver for channel subsystem
   4  *
   5  *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
   6  *                       IBM Corporation
   7  *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
   8  *               Cornelia Huck (cornelia.huck@de.ibm.com)
   9  */
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/device.h>
  13 #include <linux/slab.h>
  14 #include <linux/errno.h>
  15 #include <linux/list.h>
  16
  17 #include "css.h"
  18 #include "cio.h"
  19 #include "cio_debug.h"
  20 #include "ioasm.h"
  21 #include "chsc.h"
  22 #include "device.h"
  23
  24 int need_rescan = 0;
  25 int css_init_done = 0;
  26 static int need_reprobe = 0;
  27 static int max_ssid = 0;
  28
  29 struct channel_subsystem *css[__MAX_CSSID + 1];
  30
  31 int css_characteristics_avail = 0;
  32
  33 inline int
  34 for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
  35 {
  36         struct subchannel_id schid;
  37         int ret;
  38
  39         init_subchannel_id(&schid);
  40         ret = -ENODEV;
  41         do {
  42                 do {
  43                         ret = fn(schid, data);
  44                         if (ret)
  45                                 break;
  46                 } while (schid.sch_no++ < __MAX_SUBCHANNEL);
  47                 schid.sch_no = 0;
  48         } while (schid.ssid++ < max_ssid);
  49         return ret;
  50 }
  51
  52 static struct subchannel *
  53 css_alloc_subchannel(struct subchannel_id schid)
  54 {
  55         struct subchannel *sch;
  56         int ret;
  57
  58         sch = kmalloc (sizeof (*sch), GFP_KERNEL | GFP_DMA);
  59         if (sch == NULL)
  60                 return ERR_PTR(-ENOMEM);
  61         ret = cio_validate_subchannel (sch, schid);
  62         if (ret < 0) {
  63                 kfree(sch);
  64                 return ERR_PTR(ret);
  65         }
  66
  67         if (sch->st != SUBCHANNEL_TYPE_IO) {
  68                 /* For now we ignore all non-io subchannels. */
  69                 kfree(sch);
  70                 return ERR_PTR(-EINVAL);
  71         }
  72
  73         /*
  74          * Set intparm to subchannel address.
  75          * This is fine even on 64bit since the subchannel is always located
  76          * under 2G.
  77          */
  78         sch->schib.pmcw.intparm = (__u32)(unsigned long)sch;
  79         ret = cio_modify(sch);
  80         if (ret) {
  81                 kfree(sch);
  82                 return ERR_PTR(ret);
  83         }
  84         return sch;
  85 }
  86
  87 static void
  88 css_free_subchannel(struct subchannel *sch)
  89 {
  90         if (sch) {
  91                 /* Reset intparm to zeroes. */
  92                 sch->schib.pmcw.intparm = 0;
  93                 cio_modify(sch);
  94                 kfree(sch);
  95         }
  96
  97 }
  98
  99 static void
 100 css_subchannel_release(struct device *dev)
 101 {
 102         struct subchannel *sch;
 103
 104         sch = to_subchannel(dev);
 105         if (!cio_is_console(sch->schid))
 106                 kfree(sch);
 107 }
 108
 109 extern int css_get_ssd_info(struct subchannel *sch);
 110
 111
 112 int css_sch_device_register(struct subchannel *sch)
 113 {
 114         int ret;
 115
 116         mutex_lock(&sch->reg_mutex);
 117         ret = device_register(&sch->dev);
 118         mutex_unlock(&sch->reg_mutex);
 119         return ret;
 120 }
 121
 122 void css_sch_device_unregister(struct subchannel *sch)
 123 {
 124         mutex_lock(&sch->reg_mutex);
 125         device_unregister(&sch->dev);
 126         mutex_unlock(&sch->reg_mutex);
 127 }
 128
 129 static int
 130 css_register_subchannel(struct subchannel *sch)
 131 {
 132         int ret;
 133
 134         /* Initialize the subchannel structure */
 135         sch->dev.parent = &css[0]->device;
 136         sch->dev.bus = &css_bus_type;
 137         sch->dev.release = &css_subchannel_release;
 138
 139         /* make it known to the system */
 140         ret = css_sch_device_register(sch);
 141         if (ret)
 142                 printk (KERN_WARNING "%s: could not register %s\n",
 143                         __func__, sch->dev.bus_id);
 144         else
 145                 css_get_ssd_info(sch);
 146         return ret;
 147 }
 148
 149 int
 150 css_probe_device(struct subchannel_id schid)
 151 {
 152         int ret;
 153         struct subchannel *sch;
 154
 155         sch = css_alloc_subchannel(schid);
 156         if (IS_ERR(sch))
 157                 return PTR_ERR(sch);
 158         ret = css_register_subchannel(sch);
 159         if (ret)
 160                 css_free_subchannel(sch);
 161         return ret;
 162 }
 163
 164 static int
 165 check_subchannel(struct device * dev, void * data)
 166 {
 167         struct subchannel *sch;
 168         struct subchannel_id *schid = data;
 169
 170         sch = to_subchannel(dev);
 171         return schid_equal(&sch->schid, schid);
 172 }
 173
 174 struct subchannel *
 175 get_subchannel_by_schid(struct subchannel_id schid)
 176 {
 177         struct device *dev;
 178
 179         dev = bus_find_device(&css_bus_type, NULL,
 180                               &schid, check_subchannel);
 181
 182         return dev ? to_subchannel(dev) : NULL;
 183 }
 184
 185 static inline int css_get_subchannel_status(struct subchannel *sch)
 186 {
 187         struct schib schib;
 188
 189         if (stsch(sch->schid, &schib) || !schib.pmcw.dnv)
 190                 return CIO_GONE;
 191         if (sch->schib.pmcw.dnv && (schib.pmcw.dev != sch->schib.pmcw.dev))
 192                 return CIO_REVALIDATE;
 193         if (!sch->lpm)
 194                 return CIO_NO_PATH;
 195         return CIO_OPER;
 196 }
 197
 198 static int css_evaluate_known_subchannel(struct subchannel *sch, int slow)
 199 {
 200         int event, ret, disc;
 201         unsigned long flags;
 202         enum { NONE, UNREGISTER, UNREGISTER_PROBE, REPROBE } action;
 203
 204         spin_lock_irqsave(&sch->lock, flags);
 205         disc = device_is_disconnected(sch);
 206         if (disc && slow) {
 207                 /* Disconnected devices are evaluated directly only.*/
 208                 spin_unlock_irqrestore(&sch->lock, flags);
 209                 return 0;
 210         }
 211         /* No interrupt after machine check - kill pending timers. */
 212         device_kill_pending_timer(sch);
 213         if (!disc && !slow) {
 214                 /* Non-disconnected devices are evaluated on the slow path. */
 215                 spin_unlock_irqrestore(&sch->lock, flags);
 216                 return -EAGAIN;
 217         }
 218         event = css_get_subchannel_status(sch);
 219         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, %s, %s path.\n",
 220                       sch->schid.ssid, sch->schid.sch_no, event,
 221                       disc ? "disconnected" : "normal",
 222                       slow ? "slow" : "fast");
 223         /* Analyze subchannel status. */
 224         action = NONE;
 225         switch (event) {
 226         case CIO_NO_PATH:
 227                 if (disc) {
 228                         /* Check if paths have become available. */
 229                         action = REPROBE;
 230                         break;
 231                 }
 232                 /* fall through */
 233         case CIO_GONE:
 234                 /* Prevent unwanted effects when opening lock. */
 235                 cio_disable_subchannel(sch);
 236                 device_set_disconnected(sch);
 237                 /* Ask driver what to do with device. */
 238                 action = UNREGISTER;
 239                 if (sch->driver && sch->driver->notify) {
 240                         spin_unlock_irqrestore(&sch->lock, flags);
 241                         ret = sch->driver->notify(&sch->dev, event);
 242                         spin_lock_irqsave(&sch->lock, flags);
 243                         if (ret)
 244                                 action = NONE;
 245                 }
 246                 break;
 247         case CIO_REVALIDATE:
 248                 /* Device will be removed, so no notify necessary. */
 249                 if (disc)
 250                         /* Reprobe because immediate unregister might block. */
 251                         action = REPROBE;
 252                 else
 253                         action = UNREGISTER_PROBE;
 254                 break;
 255         case CIO_OPER:
 256                 if (disc)
 257                         /* Get device operational again. */
 258                         action = REPROBE;
 259                 break;
 260         }
 261         /* Perform action. */
 262         ret = 0;
 263         switch (action) {
 264         case UNREGISTER:
 265         case UNREGISTER_PROBE:
 266                 /* Unregister device (will use subchannel lock). */
 267                 spin_unlock_irqrestore(&sch->lock, flags);
 268                 css_sch_device_unregister(sch);
 269                 spin_lock_irqsave(&sch->lock, flags);
 270
 271                 /* Reset intparm to zeroes. */
 272                 sch->schib.pmcw.intparm = 0;
 273                 cio_modify(sch);
 274                 break;
 275         case REPROBE:
 276                 device_trigger_reprobe(sch);
 277                 break;
 278         default:
 279                 break;
 280         }
 281         spin_unlock_irqrestore(&sch->lock, flags);
 282         /* Probe if necessary. */
 283         if (action == UNREGISTER_PROBE)
 284                 ret = css_probe_device(sch->schid);
 285
 286         return ret;
 287 }
 288
 289 static int css_evaluate_new_subchannel(struct subchannel_id schid, int slow)
 290 {
 291         struct schib schib;
 292
 293         if (!slow) {
 294                 /* Will be done on the slow path. */
 295                 return -EAGAIN;
 296         }
 297         if (stsch(schid, &schib) || !schib.pmcw.dnv) {
 298                 /* Unusable - ignore. */
 299                 return 0;
 300         }
 301         CIO_MSG_EVENT(4, "Evaluating schid 0.%x.%04x, event %d, unknown, "
 302                          "slow path.\n", schid.ssid, schid.sch_no, CIO_OPER);
 303
 304         return css_probe_device(schid);
 305 }
 306
 307 static int css_evaluate_subchannel(struct subchannel_id schid, int slow)
 308 {
 309         struct subchannel *sch;
 310         int ret;
 311
 312         sch = get_subchannel_by_schid(schid);
 313         if (sch) {
 314                 ret = css_evaluate_known_subchannel(sch, slow);
 315                 put_device(&sch->dev);
 316         } else
 317                 ret = css_evaluate_new_subchannel(schid, slow);
 318
 319         return ret;
 320 }
 321
 322 static int
 323 css_rescan_devices(struct subchannel_id schid, void *data)
 324 {
 325         return css_evaluate_subchannel(schid, 1);
 326 }
 327
 328 struct slow_subchannel {
 329         struct list_head slow_list;
 330         struct subchannel_id schid;
 331 };
 332
 333 static LIST_HEAD(slow_subchannels_head);
 334 static DEFINE_SPINLOCK(slow_subchannel_lock);
 335
 336 static void
 337 css_trigger_slow_path(void)
 338 {
 339         CIO_TRACE_EVENT(4, "slowpath");
 340
 341         if (need_rescan) {
 342                 need_rescan = 0;
 343                 for_each_subchannel(css_rescan_devices, NULL);
 344                 return;
 345         }
 346
 347         spin_lock_irq(&slow_subchannel_lock);
 348         while (!list_empty(&slow_subchannels_head)) {
 349                 struct slow_subchannel *slow_sch =
 350                         list_entry(slow_subchannels_head.next,
 351                                    struct slow_subchannel, slow_list);
 352
 353                 list_del_init(slow_subchannels_head.next);
 354                 spin_unlock_irq(&slow_subchannel_lock);
 355                 css_evaluate_subchannel(slow_sch->schid, 1);
 356                 spin_lock_irq(&slow_subchannel_lock);
 357                 kfree(slow_sch);
 358         }
 359         spin_unlock_irq(&slow_subchannel_lock);
 360 }
 361
 362 typedef void (*workfunc)(void *);
 363 DECLARE_WORK(slow_path_work, (workfunc)css_trigger_slow_path, NULL);
 364 struct workqueue_struct *slow_path_wq;
 365
 366 /* Reprobe subchannel if unregistered. */
 367 static int reprobe_subchannel(struct subchannel_id schid, void *data)
 368 {
 369         struct subchannel *sch;
 370         int ret;
 371
 372         CIO_DEBUG(KERN_INFO, 6, "cio: reprobe 0.%x.%04x\n",
 373                   schid.ssid, schid.sch_no);
 374         if (need_reprobe)
 375                 return -EAGAIN;
 376
 377         sch = get_subchannel_by_schid(schid);
 378         if (sch) {
 379                 /* Already known. */
 380                 put_device(&sch->dev);
 381                 return 0;
 382         }
 383
 384         ret = css_probe_device(schid);
 385         switch (ret) {
 386         case 0:
 387                 break;
 388         case -ENXIO:
 389         case -ENOMEM:
 390                 /* These should abort looping */
 391                 break;
 392         default:
 393                 ret = 0;
 394         }
 395
 396         return ret;
 397 }
 398
 399 /* Work function used to reprobe all unregistered subchannels. */
 400 static void reprobe_all(void *data)
 401 {
 402         int ret;
 403
 404         CIO_MSG_EVENT(2, "reprobe start\n");
 405
 406         need_reprobe = 0;
 407         /* Make sure initial subchannel scan is done. */
 408         wait_event(ccw_device_init_wq,
 409                    atomic_read(&ccw_device_init_count) == 0);
 410         ret = for_each_subchannel(reprobe_subchannel, NULL);
 411
 412         CIO_MSG_EVENT(2, "reprobe done (rc=%d, need_reprobe=%d)\n", ret,
 413                       need_reprobe);
 414 }
 415
 416 DECLARE_WORK(css_reprobe_work, reprobe_all, NULL);
 417
 418 /* Schedule reprobing of all unregistered subchannels. */
 419 void css_schedule_reprobe(void)
 420 {
 421         need_reprobe = 1;
 422         queue_work(ccw_device_work, &css_reprobe_work);
 423 }
 424
 425 EXPORT_SYMBOL_GPL(css_schedule_reprobe);
 426
 427 /*
 428  * Rescan for new devices. FIXME: This is slow.
 429  * This function is called when we have lost CRWs due to overflows and we have
 430  * to do subchannel housekeeping.
 431  */
 432 void
 433 css_reiterate_subchannels(void)
 434 {
 435         css_clear_subchannel_slow_list();
 436         need_rescan = 1;
 437 }
 438
 439 /*
 440  * Called from the machine check handler for subchannel report words.
 441  */
 442 int
 443 css_process_crw(int rsid1, int rsid2)
 444 {
 445         int ret;
 446         struct subchannel_id mchk_schid;
 447
 448         CIO_CRW_EVENT(2, "source is subchannel %04X, subsystem id %x\n",
 449                       rsid1, rsid2);
 450
 451         if (need_rescan)
 452                 /* We need to iterate all subchannels anyway. */
 453                 return -EAGAIN;
 454
 455         init_subchannel_id(&mchk_schid);
 456         mchk_schid.sch_no = rsid1;
 457         if (rsid2 != 0)
 458                 mchk_schid.ssid = (rsid2 >> 8) & 3;
 459
 460         /*
 461          * Since we are always presented with IPI in the CRW, we have to
 462          * use stsch() to find out if the subchannel in question has come
 463          * or gone.
 464          */
 465         ret = css_evaluate_subchannel(mchk_schid, 0);
 466         if (ret == -EAGAIN) {
 467                 if (css_enqueue_subchannel_slow(mchk_schid)) {
 468                         css_clear_subchannel_slow_list();
 469                         need_rescan = 1;
 470                 }
 471         }
 472         return ret;
 473 }
 474
 475 static int __init
 476 __init_channel_subsystem(struct subchannel_id schid, void *data)
 477 {
 478         struct subchannel *sch;
 479         int ret;
 480
 481         if (cio_is_console(schid))
 482                 sch = cio_get_console_subchannel();
 483         else {
 484                 sch = css_alloc_subchannel(schid);
 485                 if (IS_ERR(sch))
 486                         ret = PTR_ERR(sch);
 487                 else
 488                         ret = 0;
 489                 switch (ret) {
 490                 case 0:
 491                         break;
 492                 case -ENOMEM:
 493                         panic("Out of memory in init_channel_subsystem\n");
 494                 /* -ENXIO: no more subchannels. */
 495                 case -ENXIO:
 496                         return ret;
 497                 /* -EIO: this subchannel set not supported. */
 498                 case -EIO:
 499                         return ret;
 500                 default:
 501                         return 0;
 502                 }
 503         }
 504         /*
 505          * We register ALL valid subchannels in ioinfo, even those
 506          * that have been present before init_channel_subsystem.
 507          * These subchannels can't have been registered yet (kmalloc
 508          * not working) so we do it now. This is true e.g. for the
 509          * console subchannel.
 510          */
 511         css_register_subchannel(sch);
 512         return 0;
 513 }
 514
 515 static void __init
 516 css_generate_pgid(struct channel_subsystem *css, u32 tod_high)
 517 {
 518         if (css_characteristics_avail && css_general_characteristics.mcss) {
 519                 css->global_pgid.pgid_high.ext_cssid.version = 0x80;
 520                 css->global_pgid.pgid_high.ext_cssid.cssid = css->cssid;
 521         } else {
 522 #ifdef CONFIG_SMP
 523                 css->global_pgid.pgid_high.cpu_addr = hard_smp_processor_id();
 524 #else
 525                 css->global_pgid.pgid_high.cpu_addr = 0;
 526 #endif
 527         }
 528         css->global_pgid.cpu_id = ((cpuid_t *) __LC_CPUID)->ident;
 529         css->global_pgid.cpu_model = ((cpuid_t *) __LC_CPUID)->machine;
 530         css->global_pgid.tod_high = tod_high;
 531
 532 }
 533
 534 static void
 535 channel_subsystem_release(struct device *dev)
 536 {
 537         struct channel_subsystem *css;
 538
 539         css = to_css(dev);
 540         mutex_destroy(&css->mutex);
 541         kfree(css);
 542 }
 543
 544 static ssize_t
 545 css_cm_enable_show(struct device *dev, struct device_attribute *attr,
 546                    char *buf)
 547 {
 548         struct channel_subsystem *css = to_css(dev);
 549
 550         if (!css)
 551                 return 0;
 552         return sprintf(buf, "%x\n", css->cm_enabled);
 553 }
 554
 555 static ssize_t
 556 css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 557                     const char *buf, size_t count)
 558 {
 559         struct channel_subsystem *css = to_css(dev);
 560         int ret;
 561
 562         switch (buf[0]) {
 563         case '0':
 564                 ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 565                 break;
 566         case '1':
 567                 ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 568                 break;
 569         default:
 570                 ret = -EINVAL;
 571         }
 572         return ret < 0 ? ret : count;
 573 }
 574
 575 static DEVICE_ATTR(cm_enable, 0644, css_cm_enable_show, css_cm_enable_store);
 576
 577 static inline void __init
 578 setup_css(int nr)
 579 {
 580         u32 tod_high;
 581
 582         memset(css[nr], 0, sizeof(struct channel_subsystem));
 583         mutex_init(&css[nr]->mutex);
 584         css[nr]->valid = 1;
 585         css[nr]->cssid = nr;
 586         sprintf(css[nr]->device.bus_id, "css%x", nr);
 587         css[nr]->device.release = channel_subsystem_release;
 588         tod_high = (u32) (get_clock() >> 32);
 589         css_generate_pgid(css[nr], tod_high);
 590 }
 591
 592 /*
 593  * Now that the driver core is running, we can setup our channel subsystem.
 594  * The struct subchannel's are created during probing (except for the
 595  * static console subchannel).
 596  */
 597 static int __init
 598 init_channel_subsystem (void)
 599 {
 600         int ret, i;
 601
 602         if (chsc_determine_css_characteristics() == 0)
 603                 css_characteristics_avail = 1;
 604
 605         if ((ret = bus_register(&css_bus_type)))
 606                 goto out;
 607
 608         /* Try to enable MSS. */
 609         ret = chsc_enable_facility(CHSC_SDA_OC_MSS);
 610         switch (ret) {
 611         case 0: /* Success. */
 612                 max_ssid = __MAX_SSID;
 613                 break;
 614         case -ENOMEM:
 615                 goto out_bus;
 616         default:
 617                 max_ssid = 0;
 618         }
 619         /* Setup css structure. */
 620         for (i = 0; i <= __MAX_CSSID; i++) {
 621                 css[i] = kmalloc(sizeof(struct channel_subsystem), GFP_KERNEL);
 622                 if (!css[i]) {
 623                         ret = -ENOMEM;
 624                         goto out_unregister;
 625                 }
 626                 setup_css(i);
 627                 ret = device_register(&css[i]->device);
 628                 if (ret)
 629                         goto out_free;
 630                 if (css_characteristics_avail &&
 631                     css_chsc_characteristics.secm) {
 632                         ret = device_create_file(&css[i]->device,
 633                                                  &dev_attr_cm_enable);
 634                         if (ret)
 635                                 goto out_device;
 636                 }
 637         }
 638         css_init_done = 1;
 639
 640         ctl_set_bit(6, 28);
 641
 642         for_each_subchannel(__init_channel_subsystem, NULL);
 643         return 0;
 644 out_device:
 645         device_unregister(&css[i]->device);
 646 out_free:
 647         kfree(css[i]);
 648 out_unregister:
 649         while (i > 0) {
 650                 i--;
 651                 if (css_characteristics_avail && css_chsc_characteristics.secm)
 652                         device_remove_file(&css[i]->device,
 653                                            &dev_attr_cm_enable);
 654                 device_unregister(&css[i]->device);
 655         }
 656 out_bus:
 657         bus_unregister(&css_bus_type);
 658 out:
 659         return ret;
 660 }
 661
 662 /*
 663  * find a driver for a subchannel. They identify by the subchannel
 664  * type with the exception that the console subchannel driver has its own
 665  * subchannel type although the device is an i/o subchannel
 666  */
 667 static int
 668 css_bus_match (struct device *dev, struct device_driver *drv)
 669 {
 670         struct subchannel *sch = container_of (dev, struct subchannel, dev);
 671         struct css_driver *driver = container_of (drv, struct css_driver, drv);
 672
 673         if (sch->st == driver->subchannel_type)
 674                 return 1;
 675
 676         return 0;
 677 }
 678
 679 static int
 680 css_probe (struct device *dev)
 681 {
 682         struct subchannel *sch;
 683
 684         sch = to_subchannel(dev);
 685         sch->driver = container_of (dev->driver, struct css_driver, drv);
 686         return (sch->driver->probe ? sch->driver->probe(sch) : 0);
 687 }
 688
 689 static int
 690 css_remove (struct device *dev)
 691 {
 692         struct subchannel *sch;
 693
 694         sch = to_subchannel(dev);
 695         return (sch->driver->remove ? sch->driver->remove(sch) : 0);
 696 }
 697
 698 static void
 699 css_shutdown (struct device *dev)
 700 {
 701         struct subchannel *sch;
 702
 703         sch = to_subchannel(dev);
 704         if (sch->driver->shutdown)
 705                 sch->driver->shutdown(sch);
 706 }
 707
 708 struct bus_type css_bus_type = {
 709         .name     = "css",
 710         .match    = css_bus_match,
 711         .probe    = css_probe,
 712         .remove   = css_remove,
 713         .shutdown = css_shutdown,
 714 };
 715
 716 subsys_initcall(init_channel_subsystem);
 717
 718 int
 719 css_enqueue_subchannel_slow(struct subchannel_id schid)
 720 {
 721         struct slow_subchannel *new_slow_sch;
 722         unsigned long flags;
 723
 724         new_slow_sch = kzalloc(sizeof(struct slow_subchannel), GFP_ATOMIC);
 725         if (!new_slow_sch)
 726                 return -ENOMEM;
 727         new_slow_sch->schid = schid;
 728         spin_lock_irqsave(&slow_subchannel_lock, flags);
 729         list_add_tail(&new_slow_sch->slow_list, &slow_subchannels_head);
 730         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 731         return 0;
 732 }
 733
 734 void
 735 css_clear_subchannel_slow_list(void)
 736 {
 737         unsigned long flags;
 738
 739         spin_lock_irqsave(&slow_subchannel_lock, flags);
 740         while (!list_empty(&slow_subchannels_head)) {
 741                 struct slow_subchannel *slow_sch =
 742                         list_entry(slow_subchannels_head.next,
 743                                    struct slow_subchannel, slow_list);
 744
 745                 list_del_init(slow_subchannels_head.next);
 746                 kfree(slow_sch);
 747         }
 748         spin_unlock_irqrestore(&slow_subchannel_lock, flags);
 749 }
 750
 751
 752
 753 int
 754 css_slow_subchannels_exist(void)
 755 {
 756         return (!list_empty(&slow_subchannels_head));
 757 }
 758
 759 MODULE_LICENSE("GPL");
 760 EXPORT_SYMBOL(css_bus_type);
 761 EXPORT_SYMBOL_GPL(css_characteristics_avail);