drivers/s390/char/monreader.c

   1 /*
   2  * drivers/s390/char/monreader.c
   3  *
   4  * Character device driver for reading z/VM *MONITOR service records.
   5  *
   6  * Copyright (C) 2004 IBM Corporation, IBM Deutschland Entwicklung GmbH.
   7  *
   8  * Author: Gerald Schaefer <geraldsc@de.ibm.com>
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/moduleparam.h>
  13 #include <linux/init.h>
  14 #include <linux/errno.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/ctype.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/interrupt.h>
  21 #include <asm/uaccess.h>
  22 #include <asm/ebcdic.h>
  23 #include <asm/extmem.h>
  24 #include <linux/poll.h>
  25 #include "../net/iucv.h"
  26
  27
  28 //#define MON_DEBUG                     /* Debug messages on/off */
  29
  30 #define MON_NAME "monreader"
  31
  32 #define P_INFO(x...)    printk(KERN_INFO MON_NAME " info: " x)
  33 #define P_ERROR(x...)   printk(KERN_ERR MON_NAME " error: " x)
  34 #define P_WARNING(x...) printk(KERN_WARNING MON_NAME " warning: " x)
  35
  36 #ifdef MON_DEBUG
  37 #define P_DEBUG(x...)   printk(KERN_DEBUG MON_NAME " debug: " x)
  38 #else
  39 #define P_DEBUG(x...)   do {} while (0)
  40 #endif
  41
  42 #define MON_COLLECT_SAMPLE 0x80
  43 #define MON_COLLECT_EVENT  0x40
  44 #define MON_SERVICE        "*MONITOR"
  45 #define MON_IN_USE         0x01
  46 #define MON_MSGLIM         255
  47
  48 static char mon_dcss_name[9] = "MONDCSS\0";
  49
  50 struct mon_msg {
  51         u32 pos;
  52         u32 mca_offset;
  53         iucv_MessagePending local_eib;
  54         char msglim_reached;
  55         char replied_msglim;
  56 };
  57
  58 struct mon_private {
  59         u16 pathid;
  60         iucv_handle_t iucv_handle;
  61         struct mon_msg *msg_array[MON_MSGLIM];
  62         unsigned int   write_index;
  63         unsigned int   read_index;
  64         atomic_t msglim_count;
  65         atomic_t read_ready;
  66         atomic_t iucv_connected;
  67         atomic_t iucv_severed;
  68 };
  69
  70 static unsigned long mon_in_use = 0;
  71
  72 static unsigned long mon_dcss_start;
  73 static unsigned long mon_dcss_end;
  74
  75 static DECLARE_WAIT_QUEUE_HEAD(mon_read_wait_queue);
  76 static DECLARE_WAIT_QUEUE_HEAD(mon_conn_wait_queue);
  77
  78 static u8 iucv_host[8] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
  79
  80 static u8 user_data_connect[16] = {
  81         /* Version code, must be 0x01 for shared mode */
  82         0x01,
  83         /* what to collect */
  84         MON_COLLECT_SAMPLE | MON_COLLECT_EVENT,
  85         /* DCSS name in EBCDIC, 8 bytes padded with blanks */
  86         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  87         0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  88 };
  89
  90 static u8 user_data_sever[16] = {
  91         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  92         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
  93 };
  94
  95
  96 /******************************************************************************
  97  *                             helper functions                               *
  98  *****************************************************************************/
  99 /*
 100  * Create the 8 bytes EBCDIC DCSS segment name from
 101  * an ASCII name, incl. padding
 102  */
 103 static inline void
 104 dcss_mkname(char *ascii_name, char *ebcdic_name)
 105 {
 106         int i;
 107
 108         for (i = 0; i < 8; i++) {
 109                 if (ascii_name[i] == '\0')
 110                         break;
 111                 ebcdic_name[i] = toupper(ascii_name[i]);
 112         };
 113         for (; i < 8; i++)
 114                 ebcdic_name[i] = ' ';
 115         ASCEBC(ebcdic_name, 8);
 116 }
 117
 118 /*
 119  * print appropriate error message for segment_load()/segment_type()
 120  * return code
 121  */
 122 static void
 123 mon_segment_warn(int rc, char* seg_name)
 124 {
 125         switch (rc) {
 126         case -ENOENT:
 127                 P_WARNING("cannot load/query segment %s, does not exist\n",
 128                           seg_name);
 129                 break;
 130         case -ENOSYS:
 131                 P_WARNING("cannot load/query segment %s, not running on VM\n",
 132                           seg_name);
 133                 break;
 134         case -EIO:
 135                 P_WARNING("cannot load/query segment %s, hardware error\n",
 136                           seg_name);
 137                 break;
 138         case -ENOTSUPP:
 139                 P_WARNING("cannot load/query segment %s, is a multi-part "
 140                           "segment\n", seg_name);
 141                 break;
 142         case -ENOSPC:
 143                 P_WARNING("cannot load/query segment %s, overlaps with "
 144                           "storage\n", seg_name);
 145                 break;
 146         case -EBUSY:
 147                 P_WARNING("cannot load/query segment %s, overlaps with "
 148                           "already loaded dcss\n", seg_name);
 149                 break;
 150         case -EPERM:
 151                 P_WARNING("cannot load/query segment %s, already loaded in "
 152                           "incompatible mode\n", seg_name);
 153                 break;
 154         case -ENOMEM:
 155                 P_WARNING("cannot load/query segment %s, out of memory\n",
 156                           seg_name);
 157                 break;
 158         case -ERANGE:
 159                 P_WARNING("cannot load/query segment %s, exceeds kernel "
 160                           "mapping range\n", seg_name);
 161                 break;
 162         default:
 163                 P_WARNING("cannot load/query segment %s, return value %i\n",
 164                           seg_name, rc);
 165                 break;
 166         }
 167 }
 168
 169 static inline unsigned long
 170 mon_mca_start(struct mon_msg *monmsg)
 171 {
 172         return monmsg->local_eib.ln1msg1.iprmmsg1_u32;
 173 }
 174
 175 static inline unsigned long
 176 mon_mca_end(struct mon_msg *monmsg)
 177 {
 178         return monmsg->local_eib.ln1msg2.ipbfln1f;
 179 }
 180
 181 static inline u8
 182 mon_mca_type(struct mon_msg *monmsg, u8 index)
 183 {
 184         return *((u8 *) mon_mca_start(monmsg) + monmsg->mca_offset + index);
 185 }
 186
 187 static inline u32
 188 mon_mca_size(struct mon_msg *monmsg)
 189 {
 190         return mon_mca_end(monmsg) - mon_mca_start(monmsg) + 1;
 191 }
 192
 193 static inline u32
 194 mon_rec_start(struct mon_msg *monmsg)
 195 {
 196         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 4));
 197 }
 198
 199 static inline u32
 200 mon_rec_end(struct mon_msg *monmsg)
 201 {
 202         return *((u32 *) (mon_mca_start(monmsg) + monmsg->mca_offset + 8));
 203 }
 204
 205 static inline int
 206 mon_check_mca(struct mon_msg *monmsg)
 207 {
 208         if ((mon_rec_end(monmsg) <= mon_rec_start(monmsg)) ||
 209             (mon_rec_start(monmsg) < mon_dcss_start) ||
 210             (mon_rec_end(monmsg) > mon_dcss_end) ||
 211             (mon_mca_type(monmsg, 0) == 0) ||
 212             (mon_mca_size(monmsg) % 12 != 0) ||
 213             (mon_mca_end(monmsg) <= mon_mca_start(monmsg)) ||
 214             (mon_mca_end(monmsg) > mon_dcss_end) ||
 215             (mon_mca_start(monmsg) < mon_dcss_start) ||
 216             ((mon_mca_type(monmsg, 1) == 0) && (mon_mca_type(monmsg, 2) == 0)))
 217         {
 218                 P_DEBUG("READ, IGNORED INVALID MCA\n\n");
 219                 return -EINVAL;
 220         }
 221         return 0;
 222 }
 223
 224 static inline int
 225 mon_send_reply(struct mon_msg *monmsg, struct mon_private *monpriv)
 226 {
 227         u8 prmmsg[8];
 228         int rc;
 229
 230         P_DEBUG("read, REPLY: pathid = 0x%04X, msgid = 0x%08X, trgcls = "
 231                 "0x%08X\n\n",
 232                 monmsg->local_eib.ippathid, monmsg->local_eib.ipmsgid,
 233                 monmsg->local_eib.iptrgcls);
 234         rc = iucv_reply_prmmsg(monmsg->local_eib.ippathid,
 235                                 monmsg->local_eib.ipmsgid,
 236                                 monmsg->local_eib.iptrgcls,
 237                                 0, prmmsg);
 238         atomic_dec(&monpriv->msglim_count);
 239         if (likely(!monmsg->msglim_reached)) {
 240                 monmsg->pos = 0;
 241                 monmsg->mca_offset = 0;
 242                 monpriv->read_index = (monpriv->read_index + 1) %
 243                                       MON_MSGLIM;
 244                 atomic_dec(&monpriv->read_ready);
 245         } else
 246                 monmsg->replied_msglim = 1;
 247         if (rc) {
 248                 P_ERROR("read, IUCV reply failed with rc = %i\n\n", rc);
 249                 return -EIO;
 250         }
 251         return 0;
 252 }
 253
 254 static inline struct mon_private *
 255 mon_alloc_mem(void)
 256 {
 257         int i,j;
 258         struct mon_private *monpriv;
 259
 260         monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
 261         if (!monpriv) {
 262                 P_ERROR("no memory for monpriv\n");
 263                 return NULL;
 264         }
 265         for (i = 0; i < MON_MSGLIM; i++) {
 266                 monpriv->msg_array[i] = kzalloc(sizeof(struct mon_msg),
 267                                                     GFP_KERNEL);
 268                 if (!monpriv->msg_array[i]) {
 269                         P_ERROR("open, no memory for msg_array\n");
 270                         for (j = 0; j < i; j++)
 271                                 kfree(monpriv->msg_array[j]);
 272                         return NULL;
 273                 }
 274         }
 275         return monpriv;
 276 }
 277
 278 static inline void
 279 mon_read_debug(struct mon_msg *monmsg, struct mon_private *monpriv)
 280 {
 281 #ifdef MON_DEBUG
 282         u8 msg_type[2], mca_type;
 283         unsigned long records_len;
 284
 285         records_len = mon_rec_end(monmsg) - mon_rec_start(monmsg) + 1;
 286
 287         memcpy(msg_type, &monmsg->local_eib.iptrgcls, 2);
 288         EBCASC(msg_type, 2);
 289         mca_type = mon_mca_type(monmsg, 0);
 290         EBCASC(&mca_type, 1);
 291
 292         P_DEBUG("read, mon_read_index = %i, mon_write_index = %i\n",
 293                 monpriv->read_index, monpriv->write_index);
 294         P_DEBUG("read, pathid = 0x%04X, msgid = 0x%08X, trgcls = 0x%08X\n",
 295                 monmsg->local_eib.ippathid, monmsg->local_eib.ipmsgid,
 296                 monmsg->local_eib.iptrgcls);
 297         P_DEBUG("read, msg_type = '%c%c', mca_type = '%c' / 0x%X / 0x%X\n",
 298                 msg_type[0], msg_type[1], mca_type ? mca_type : 'X',
 299                 mon_mca_type(monmsg, 1), mon_mca_type(monmsg, 2));
 300         P_DEBUG("read, MCA: start = 0x%lX, end = 0x%lX\n",
 301                 mon_mca_start(monmsg), mon_mca_end(monmsg));
 302         P_DEBUG("read, REC: start = 0x%X, end = 0x%X, len = %lu\n\n",
 303                 mon_rec_start(monmsg), mon_rec_end(monmsg), records_len);
 304         if (mon_mca_size(monmsg) > 12)
 305                 P_DEBUG("READ, MORE THAN ONE MCA\n\n");
 306 #endif
 307 }
 308
 309 static inline void
 310 mon_next_mca(struct mon_msg *monmsg)
 311 {
 312         if (likely((mon_mca_size(monmsg) - monmsg->mca_offset) == 12))
 313                 return;
 314         P_DEBUG("READ, NEXT MCA\n\n");
 315         monmsg->mca_offset += 12;
 316         monmsg->pos = 0;
 317 }
 318
 319 static inline struct mon_msg *
 320 mon_next_message(struct mon_private *monpriv)
 321 {
 322         struct mon_msg *monmsg;
 323
 324         if (!atomic_read(&monpriv->read_ready))
 325                 return NULL;
 326         monmsg = monpriv->msg_array[monpriv->read_index];
 327         if (unlikely(monmsg->replied_msglim)) {
 328                 monmsg->replied_msglim = 0;
 329                 monmsg->msglim_reached = 0;
 330                 monmsg->pos = 0;
 331                 monmsg->mca_offset = 0;
 332                 P_WARNING("read, message limit reached\n");
 333                 monpriv->read_index = (monpriv->read_index + 1) %
 334                                       MON_MSGLIM;
 335                 atomic_dec(&monpriv->read_ready);
 336                 return ERR_PTR(-EOVERFLOW);
 337         }
 338         return monmsg;
 339 }
 340
 341
 342 /******************************************************************************
 343  *                               IUCV handler                                 *
 344  *****************************************************************************/
 345 static void
 346 mon_iucv_ConnectionComplete(iucv_ConnectionComplete *eib, void *pgm_data)
 347 {
 348         struct mon_private *monpriv = (struct mon_private *) pgm_data;
 349
 350         P_DEBUG("IUCV connection completed\n");
 351         P_DEBUG("IUCV ACCEPT (from *MONITOR): Version = 0x%02X, Event = "
 352                 "0x%02X, Sample = 0x%02X\n",
 353                 eib->ipuser[0], eib->ipuser[1], eib->ipuser[2]);
 354         atomic_set(&monpriv->iucv_connected, 1);
 355         wake_up(&mon_conn_wait_queue);
 356 }
 357
 358 static void
 359 mon_iucv_ConnectionSevered(iucv_ConnectionSevered *eib, void *pgm_data)
 360 {
 361         struct mon_private *monpriv = (struct mon_private *) pgm_data;
 362
 363         P_ERROR("IUCV connection severed with rc = 0x%X\n",
 364                 (u8) eib->ipuser[0]);
 365         atomic_set(&monpriv->iucv_severed, 1);
 366         wake_up(&mon_conn_wait_queue);
 367         wake_up_interruptible(&mon_read_wait_queue);
 368 }
 369
 370 static void
 371 mon_iucv_MessagePending(iucv_MessagePending *eib, void *pgm_data)
 372 {
 373         struct mon_private *monpriv = (struct mon_private *) pgm_data;
 374
 375         P_DEBUG("IUCV message pending\n");
 376         memcpy(&monpriv->msg_array[monpriv->write_index]->local_eib, eib,
 377                sizeof(iucv_MessagePending));
 378         if (atomic_inc_return(&monpriv->msglim_count) == MON_MSGLIM) {
 379                 P_WARNING("IUCV message pending, message limit (%i) reached\n",
 380                           MON_MSGLIM);
 381                 monpriv->msg_array[monpriv->write_index]->msglim_reached = 1;
 382         }
 383         monpriv->write_index = (monpriv->write_index + 1) % MON_MSGLIM;
 384         atomic_inc(&monpriv->read_ready);
 385         wake_up_interruptible(&mon_read_wait_queue);
 386 }
 387
 388 static iucv_interrupt_ops_t mon_iucvops = {
 389         .ConnectionComplete = mon_iucv_ConnectionComplete,
 390         .ConnectionSevered  = mon_iucv_ConnectionSevered,
 391         .MessagePending     = mon_iucv_MessagePending,
 392 };
 393
 394 /******************************************************************************
 395  *                               file operations                              *
 396  *****************************************************************************/
 397 static int
 398 mon_open(struct inode *inode, struct file *filp)
 399 {
 400         int rc, i;
 401         struct mon_private *monpriv;
 402
 403         /*
 404          * only one user allowed
 405          */
 406         if (test_and_set_bit(MON_IN_USE, &mon_in_use))
 407                 return -EBUSY;
 408
 409         monpriv = mon_alloc_mem();
 410         if (!monpriv)
 411                 return -ENOMEM;
 412
 413         /*
 414          * Register with IUCV and connect to *MONITOR service
 415          */
 416         monpriv->iucv_handle = iucv_register_program("my_monreader    ",
 417                                                         MON_SERVICE,
 418                                                         NULL,
 419                                                         &mon_iucvops,
 420                                                         monpriv);
 421         if (!monpriv->iucv_handle) {
 422                 P_ERROR("failed to register with iucv driver\n");
 423                 rc = -EIO;
 424                 goto out_error;
 425         }
 426         P_INFO("open, registered with IUCV\n");
 427
 428         rc = iucv_connect(&monpriv->pathid, MON_MSGLIM, user_data_connect,
 429                           MON_SERVICE, iucv_host, IPRMDATA, NULL, NULL,
 430                           monpriv->iucv_handle, NULL);
 431         if (rc) {
 432                 P_ERROR("iucv connection to *MONITOR failed with "
 433                         "IPUSER SEVER code = %i\n", rc);
 434                 rc = -EIO;
 435                 goto out_unregister;
 436         }
 437         /*
 438          * Wait for connection confirmation
 439          */
 440         wait_event(mon_conn_wait_queue,
 441                    atomic_read(&monpriv->iucv_connected) ||
 442                    atomic_read(&monpriv->iucv_severed));
 443         if (atomic_read(&monpriv->iucv_severed)) {
 444                 atomic_set(&monpriv->iucv_severed, 0);
 445                 atomic_set(&monpriv->iucv_connected, 0);
 446                 rc = -EIO;
 447                 goto out_unregister;
 448         }
 449         P_INFO("open, established connection to *MONITOR service\n\n");
 450         filp->private_data = monpriv;
 451         return nonseekable_open(inode, filp);
 452
 453 out_unregister:
 454         iucv_unregister_program(monpriv->iucv_handle);
 455 out_error:
 456         for (i = 0; i < MON_MSGLIM; i++)
 457                 kfree(monpriv->msg_array[i]);
 458         kfree(monpriv);
 459         clear_bit(MON_IN_USE, &mon_in_use);
 460         return rc;
 461 }
 462
 463 static int
 464 mon_close(struct inode *inode, struct file *filp)
 465 {
 466         int rc, i;
 467         struct mon_private *monpriv = filp->private_data;
 468
 469         /*
 470          * Close IUCV connection and unregister
 471          */
 472         rc = iucv_sever(monpriv->pathid, user_data_sever);
 473         if (rc)
 474                 P_ERROR("close, iucv_sever failed with rc = %i\n", rc);
 475         else
 476                 P_INFO("close, terminated connection to *MONITOR service\n");
 477
 478         rc = iucv_unregister_program(monpriv->iucv_handle);
 479         if (rc)
 480                 P_ERROR("close, iucv_unregister failed with rc = %i\n", rc);
 481         else
 482                 P_INFO("close, unregistered with IUCV\n");
 483
 484         atomic_set(&monpriv->iucv_severed, 0);
 485         atomic_set(&monpriv->iucv_connected, 0);
 486         atomic_set(&monpriv->read_ready, 0);
 487         atomic_set(&monpriv->msglim_count, 0);
 488         monpriv->write_index  = 0;
 489         monpriv->read_index   = 0;
 490
 491         for (i = 0; i < MON_MSGLIM; i++)
 492                 kfree(monpriv->msg_array[i]);
 493         kfree(monpriv);
 494         clear_bit(MON_IN_USE, &mon_in_use);
 495         return 0;
 496 }
 497
 498 static ssize_t
 499 mon_read(struct file *filp, char __user *data, size_t count, loff_t *ppos)
 500 {
 501         struct mon_private *monpriv = filp->private_data;
 502         struct mon_msg *monmsg;
 503         int ret;
 504         u32 mce_start;
 505
 506         monmsg = mon_next_message(monpriv);
 507         if (IS_ERR(monmsg))
 508                 return PTR_ERR(monmsg);
 509
 510         if (!monmsg) {
 511                 if (filp->f_flags & O_NONBLOCK)
 512                         return -EAGAIN;
 513                 ret = wait_event_interruptible(mon_read_wait_queue,
 514                                         atomic_read(&monpriv->read_ready) ||
 515                                         atomic_read(&monpriv->iucv_severed));
 516                 if (ret)
 517                         return ret;
 518                 if (unlikely(atomic_read(&monpriv->iucv_severed)))
 519                         return -EIO;
 520                 monmsg = monpriv->msg_array[monpriv->read_index];
 521         }
 522
 523         if (!monmsg->pos) {
 524                 monmsg->pos = mon_mca_start(monmsg) + monmsg->mca_offset;
 525                 mon_read_debug(monmsg, monpriv);
 526         }
 527         if (mon_check_mca(monmsg))
 528                 goto reply;
 529
 530         /* read monitor control element (12 bytes) first */
 531         mce_start = mon_mca_start(monmsg) + monmsg->mca_offset;
 532         if ((monmsg->pos >= mce_start) && (monmsg->pos < mce_start + 12)) {
 533                 count = min(count, (size_t) mce_start + 12 - monmsg->pos);
 534                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 535                                    count);
 536                 if (ret)
 537                         return -EFAULT;
 538                 monmsg->pos += count;
 539                 if (monmsg->pos == mce_start + 12)
 540                         monmsg->pos = mon_rec_start(monmsg);
 541                 goto out_copy;
 542         }
 543
 544         /* read records */
 545         if (monmsg->pos <= mon_rec_end(monmsg)) {
 546                 count = min(count, (size_t) mon_rec_end(monmsg) - monmsg->pos
 547                                             + 1);
 548                 ret = copy_to_user(data, (void *) (unsigned long) monmsg->pos,
 549                                    count);
 550                 if (ret)
 551                         return -EFAULT;
 552                 monmsg->pos += count;
 553                 if (monmsg->pos > mon_rec_end(monmsg))
 554                         mon_next_mca(monmsg);
 555                 goto out_copy;
 556         }
 557 reply:
 558         ret = mon_send_reply(monmsg, monpriv);
 559         return ret;
 560
 561 out_copy:
 562         *ppos += count;
 563         return count;
 564 }
 565
 566 static unsigned int
 567 mon_poll(struct file *filp, struct poll_table_struct *p)
 568 {
 569         struct mon_private *monpriv = filp->private_data;
 570
 571         poll_wait(filp, &mon_read_wait_queue, p);
 572         if (unlikely(atomic_read(&monpriv->iucv_severed)))
 573                 return POLLERR;
 574         if (atomic_read(&monpriv->read_ready))
 575                 return POLLIN | POLLRDNORM;
 576         return 0;
 577 }
 578
 579 static struct file_operations mon_fops = {
 580         .owner   = THIS_MODULE,
 581         .open    = &mon_open,
 582         .release = &mon_close,
 583         .read    = &mon_read,
 584         .poll    = &mon_poll,
 585 };
 586
 587 static struct miscdevice mon_dev = {
 588         .name       = "monreader",
 589         .devfs_name = "monreader",
 590         .fops       = &mon_fops,
 591         .minor      = MISC_DYNAMIC_MINOR,
 592 };
 593
 594 /******************************************************************************
 595  *                              module init/exit                              *
 596  *****************************************************************************/
 597 static int __init
 598 mon_init(void)
 599 {
 600         int rc;
 601
 602         if (!MACHINE_IS_VM) {
 603                 P_ERROR("not running under z/VM, driver not loaded\n");
 604                 return -ENODEV;
 605         }
 606
 607         rc = segment_type(mon_dcss_name);
 608         if (rc < 0) {
 609                 mon_segment_warn(rc, mon_dcss_name);
 610                 return rc;
 611         }
 612         if (rc != SEG_TYPE_SC) {
 613                 P_ERROR("segment %s has unsupported type, should be SC\n",
 614                         mon_dcss_name);
 615                 return -EINVAL;
 616         }
 617
 618         rc = segment_load(mon_dcss_name, SEGMENT_SHARED,
 619                           &mon_dcss_start, &mon_dcss_end);
 620         if (rc < 0) {
 621                 mon_segment_warn(rc, mon_dcss_name);
 622                 return -EINVAL;
 623         }
 624         dcss_mkname(mon_dcss_name, &user_data_connect[8]);
 625
 626         rc = misc_register(&mon_dev);
 627         if (rc < 0 ) {
 628                 P_ERROR("misc_register failed, rc = %i\n", rc);
 629                 goto out;
 630         }
 631         P_INFO("Loaded segment %s from %p to %p, size = %lu Byte\n",
 632                 mon_dcss_name, (void *) mon_dcss_start, (void *) mon_dcss_end,
 633                 mon_dcss_end - mon_dcss_start + 1);
 634         return 0;
 635
 636 out:
 637         segment_unload(mon_dcss_name);
 638         return rc;
 639 }
 640
 641 static void __exit
 642 mon_exit(void)
 643 {
 644         segment_unload(mon_dcss_name);
 645         WARN_ON(misc_deregister(&mon_dev) != 0);
 646         return;
 647 }
 648
 649
 650 module_init(mon_init);
 651 module_exit(mon_exit);
 652
 653 module_param_string(mondcss, mon_dcss_name, 9, 0444);
 654 MODULE_PARM_DESC(mondcss, "Name of DCSS segment to be used for *MONITOR "
 655                  "service, max. 8 chars. Default is MONDCSS");
 656
 657 MODULE_AUTHOR("Gerald Schaefer <geraldsc@de.ibm.com>");
 658 MODULE_DESCRIPTION("Character device driver for reading z/VM "
 659                    "monitor service records.");
 660 MODULE_LICENSE("GPL");