drivers/misc/sgi-xp/xpc_main.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (c) 2004-2009 Silicon Graphics, Inc.  All Rights Reserved.
   7  */
   8
   9 /*
  10  * Cross Partition Communication (XPC) support - standard version.
  11  *
  12  *      XPC provides a message passing capability that crosses partition
  13  *      boundaries. This module is made up of two parts:
  14  *
  15  *          partition   This part detects the presence/absence of other
  16  *                      partitions. It provides a heartbeat and monitors
  17  *                      the heartbeats of other partitions.
  18  *
  19  *          channel     This part manages the channels and sends/receives
  20  *                      messages across them to/from other partitions.
  21  *
  22  *      There are a couple of additional functions residing in XP, which
  23  *      provide an interface to XPC for its users.
  24  *
  25  *
  26  *      Caveats:
  27  *
  28  *        . Currently on sn2, we have no way to determine which nasid an IRQ
  29  *          came from. Thus, xpc_send_IRQ_sn2() does a remote amo write
  30  *          followed by an IPI. The amo indicates where data is to be pulled
  31  *          from, so after the IPI arrives, the remote partition checks the amo
  32  *          word. The IPI can actually arrive before the amo however, so other
  33  *          code must periodically check for this case. Also, remote amo
  34  *          operations do not reliably time out. Thus we do a remote PIO read
  35  *          solely to know whether the remote partition is down and whether we
  36  *          should stop sending IPIs to it. This remote PIO read operation is
  37  *          set up in a special nofault region so SAL knows to ignore (and
  38  *          cleanup) any errors due to the remote amo write, PIO read, and/or
  39  *          PIO write operations.
  40  *
  41  *          If/when new hardware solves this IPI problem, we should abandon
  42  *          the current approach.
  43  *
  44  */
  45
  46 #include <linux/module.h>
  47 #include <linux/slab.h>
  48 #include <linux/sysctl.h>
  49 #include <linux/device.h>
  50 #include <linux/delay.h>
  51 #include <linux/reboot.h>
  52 #include <linux/kdebug.h>
  53 #include <linux/kthread.h>
  54 #include "xpc.h"
  55
  56 #ifdef CONFIG_X86_64
  57 #include <asm/traps.h>
  58 #endif
  59
  60 /* define two XPC debug device structures to be used with dev_dbg() et al */
  61
  62 struct device_driver xpc_dbg_name = {
  63         .name = "xpc"
  64 };
  65
  66 struct device xpc_part_dbg_subname = {
  67         .init_name = "",        /* set to "part" at xpc_init() time */
  68         .driver = &xpc_dbg_name
  69 };
  70
  71 struct device xpc_chan_dbg_subname = {
  72         .init_name = "",        /* set to "chan" at xpc_init() time */
  73         .driver = &xpc_dbg_name
  74 };
  75
  76 struct device *xpc_part = &xpc_part_dbg_subname;
  77 struct device *xpc_chan = &xpc_chan_dbg_subname;
  78
  79 static int xpc_kdebug_ignore;
  80
  81 /* systune related variables for /proc/sys directories */
  82
  83 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
  84 static int xpc_hb_min_interval = 1;
  85 static int xpc_hb_max_interval = 10;
  86
  87 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
  88 static int xpc_hb_check_min_interval = 10;
  89 static int xpc_hb_check_max_interval = 120;
  90
  91 int xpc_disengage_timelimit = XPC_DISENGAGE_DEFAULT_TIMELIMIT;
  92 static int xpc_disengage_min_timelimit; /* = 0 */
  93 static int xpc_disengage_max_timelimit = 120;
  94
  95 static struct ctl_table xpc_sys_xpc_hb_dir[] = {
  96         {
  97          .procname = "hb_interval",
  98          .data = &xpc_hb_interval,
  99          .maxlen = sizeof(int),
 100          .mode = 0644,
 101          .proc_handler = proc_dointvec_minmax,
 102          .extra1 = &xpc_hb_min_interval,
 103          .extra2 = &xpc_hb_max_interval},
 104         {
 105          .procname = "hb_check_interval",
 106          .data = &xpc_hb_check_interval,
 107          .maxlen = sizeof(int),
 108          .mode = 0644,
 109          .proc_handler = proc_dointvec_minmax,
 110          .extra1 = &xpc_hb_check_min_interval,
 111          .extra2 = &xpc_hb_check_max_interval},
 112         {}
 113 };
 114 static struct ctl_table xpc_sys_xpc_dir[] = {
 115         {
 116          .procname = "hb",
 117          .mode = 0555,
 118          .child = xpc_sys_xpc_hb_dir},
 119         {
 120          .procname = "disengage_timelimit",
 121          .data = &xpc_disengage_timelimit,
 122          .maxlen = sizeof(int),
 123          .mode = 0644,
 124          .proc_handler = proc_dointvec_minmax,
 125          .extra1 = &xpc_disengage_min_timelimit,
 126          .extra2 = &xpc_disengage_max_timelimit},
 127         {}
 128 };
 129 static struct ctl_table xpc_sys_dir[] = {
 130         {
 131          .procname = "xpc",
 132          .mode = 0555,
 133          .child = xpc_sys_xpc_dir},
 134         {}
 135 };
 136 static struct ctl_table_header *xpc_sysctl;
 137
 138 /* non-zero if any remote partition disengage was timed out */
 139 int xpc_disengage_timedout;
 140
 141 /* #of activate IRQs received and not yet processed */
 142 int xpc_activate_IRQ_rcvd;
 143 DEFINE_SPINLOCK(xpc_activate_IRQ_rcvd_lock);
 144
 145 /* IRQ handler notifies this wait queue on receipt of an IRQ */
 146 DECLARE_WAIT_QUEUE_HEAD(xpc_activate_IRQ_wq);
 147
 148 static unsigned long xpc_hb_check_timeout;
 149 static struct timer_list xpc_hb_timer;
 150
 151 /* notification that the xpc_hb_checker thread has exited */
 152 static DECLARE_COMPLETION(xpc_hb_checker_exited);
 153
 154 /* notification that the xpc_discovery thread has exited */
 155 static DECLARE_COMPLETION(xpc_discovery_exited);
 156
 157 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
 158
 159 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
 160 static struct notifier_block xpc_reboot_notifier = {
 161         .notifier_call = xpc_system_reboot,
 162 };
 163
 164 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
 165 static struct notifier_block xpc_die_notifier = {
 166         .notifier_call = xpc_system_die,
 167 };
 168
 169 struct xpc_arch_operations xpc_arch_ops;
 170
 171 /*
 172  * Timer function to enforce the timelimit on the partition disengage.
 173  */
 174 static void
 175 xpc_timeout_partition_disengage(struct timer_list *t)
 176 {
 177         struct xpc_partition *part = from_timer(part, t, disengage_timer);
 178
 179         DBUG_ON(time_is_after_jiffies(part->disengage_timeout));
 180
 181         (void)xpc_partition_disengaged(part);
 182
 183         DBUG_ON(part->disengage_timeout != 0);
 184         DBUG_ON(xpc_arch_ops.partition_engaged(XPC_PARTID(part)));
 185 }
 186
 187 /*
 188  * Timer to produce the heartbeat.  The timer structures function is
 189  * already set when this is initially called.  A tunable is used to
 190  * specify when the next timeout should occur.
 191  */
 192 static void
 193 xpc_hb_beater(struct timer_list *unused)
 194 {
 195         xpc_arch_ops.increment_heartbeat();
 196
 197         if (time_is_before_eq_jiffies(xpc_hb_check_timeout))
 198                 wake_up_interruptible(&xpc_activate_IRQ_wq);
 199
 200         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
 201         add_timer(&xpc_hb_timer);
 202 }
 203
 204 static void
 205 xpc_start_hb_beater(void)
 206 {
 207         xpc_arch_ops.heartbeat_init();
 208         timer_setup(&xpc_hb_timer, xpc_hb_beater, 0);
 209         xpc_hb_beater(0);
 210 }
 211
 212 static void
 213 xpc_stop_hb_beater(void)
 214 {
 215         del_timer_sync(&xpc_hb_timer);
 216         xpc_arch_ops.heartbeat_exit();
 217 }
 218
 219 /*
 220  * At periodic intervals, scan through all active partitions and ensure
 221  * their heartbeat is still active.  If not, the partition is deactivated.
 222  */
 223 static void
 224 xpc_check_remote_hb(void)
 225 {
 226         struct xpc_partition *part;
 227         short partid;
 228         enum xp_retval ret;
 229
 230         for (partid = 0; partid < xp_max_npartitions; partid++) {
 231
 232                 if (xpc_exiting)
 233                         break;
 234
 235                 if (partid == xp_partition_id)
 236                         continue;
 237
 238                 part = &xpc_partitions[partid];
 239
 240                 if (part->act_state == XPC_P_AS_INACTIVE ||
 241                     part->act_state == XPC_P_AS_DEACTIVATING) {
 242                         continue;
 243                 }
 244
 245                 ret = xpc_arch_ops.get_remote_heartbeat(part);
 246                 if (ret != xpSuccess)
 247                         XPC_DEACTIVATE_PARTITION(part, ret);
 248         }
 249 }
 250
 251 /*
 252  * This thread is responsible for nearly all of the partition
 253  * activation/deactivation.
 254  */
 255 static int
 256 xpc_hb_checker(void *ignore)
 257 {
 258         int force_IRQ = 0;
 259
 260         /* this thread was marked active by xpc_hb_init() */
 261
 262         set_cpus_allowed_ptr(current, cpumask_of(XPC_HB_CHECK_CPU));
 263
 264         /* set our heartbeating to other partitions into motion */
 265         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
 266         xpc_start_hb_beater();
 267
 268         while (!xpc_exiting) {
 269
 270                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
 271                         "been received\n",
 272                         (int)(xpc_hb_check_timeout - jiffies),
 273                         xpc_activate_IRQ_rcvd);
 274
 275                 /* checking of remote heartbeats is skewed by IRQ handling */
 276                 if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) {
 277                         xpc_hb_check_timeout = jiffies +
 278                             (xpc_hb_check_interval * HZ);
 279
 280                         dev_dbg(xpc_part, "checking remote heartbeats\n");
 281                         xpc_check_remote_hb();
 282
 283                         /*
 284                          * On sn2 we need to periodically recheck to ensure no
 285                          * IRQ/amo pairs have been missed.
 286                          */
 287                         if (is_shub())
 288                                 force_IRQ = 1;
 289                 }
 290
 291                 /* check for outstanding IRQs */
 292                 if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
 293                         force_IRQ = 0;
 294                         dev_dbg(xpc_part, "processing activate IRQs "
 295                                 "received\n");
 296                         xpc_arch_ops.process_activate_IRQ_rcvd();
 297                 }
 298
 299                 /* wait for IRQ or timeout */
 300                 (void)wait_event_interruptible(xpc_activate_IRQ_wq,
 301                                                (time_is_before_eq_jiffies(
 302                                                 xpc_hb_check_timeout) ||
 303                                                 xpc_activate_IRQ_rcvd > 0 ||
 304                                                 xpc_exiting));
 305         }
 306
 307         xpc_stop_hb_beater();
 308
 309         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 310
 311         /* mark this thread as having exited */
 312         complete(&xpc_hb_checker_exited);
 313         return 0;
 314 }
 315
 316 /*
 317  * This thread will attempt to discover other partitions to activate
 318  * based on info provided by SAL. This new thread is short lived and
 319  * will exit once discovery is complete.
 320  */
 321 static int
 322 xpc_initiate_discovery(void *ignore)
 323 {
 324         xpc_discovery();
 325
 326         dev_dbg(xpc_part, "discovery thread is exiting\n");
 327
 328         /* mark this thread as having exited */
 329         complete(&xpc_discovery_exited);
 330         return 0;
 331 }
 332
 333 /*
 334  * The first kthread assigned to a newly activated partition is the one
 335  * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
 336  * that kthread until the partition is brought down, at which time that kthread
 337  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
 338  * that XPC has dismantled all communication infrastructure for the associated
 339  * partition.) This kthread becomes the channel manager for that partition.
 340  *
 341  * Each active partition has a channel manager, who, besides connecting and
 342  * disconnecting channels, will ensure that each of the partition's connected
 343  * channels has the required number of assigned kthreads to get the work done.
 344  */
 345 static void
 346 xpc_channel_mgr(struct xpc_partition *part)
 347 {
 348         while (part->act_state != XPC_P_AS_DEACTIVATING ||
 349                atomic_read(&part->nchannels_active) > 0 ||
 350                !xpc_partition_disengaged(part)) {
 351
 352                 xpc_process_sent_chctl_flags(part);
 353
 354                 /*
 355                  * Wait until we've been requested to activate kthreads or
 356                  * all of the channel's message queues have been torn down or
 357                  * a signal is pending.
 358                  *
 359                  * The channel_mgr_requests is set to 1 after being awakened,
 360                  * This is done to prevent the channel mgr from making one pass
 361                  * through the loop for each request, since he will
 362                  * be servicing all the requests in one pass. The reason it's
 363                  * set to 1 instead of 0 is so that other kthreads will know
 364                  * that the channel mgr is running and won't bother trying to
 365                  * wake him up.
 366                  */
 367                 atomic_dec(&part->channel_mgr_requests);
 368                 (void)wait_event_interruptible(part->channel_mgr_wq,
 369                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
 370                                  part->chctl.all_flags != 0 ||
 371                                  (part->act_state == XPC_P_AS_DEACTIVATING &&
 372                                  atomic_read(&part->nchannels_active) == 0 &&
 373                                  xpc_partition_disengaged(part))));
 374                 atomic_set(&part->channel_mgr_requests, 1);
 375         }
 376 }
 377
 378 /*
 379  * Guarantee that the kzalloc'd memory is cacheline aligned.
 380  */
 381 void *
 382 xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
 383 {
 384         /* see if kzalloc will give us cachline aligned memory by default */
 385         *base = kzalloc(size, flags);
 386         if (*base == NULL)
 387                 return NULL;
 388
 389         if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
 390                 return *base;
 391
 392         kfree(*base);
 393
 394         /* nope, we'll have to do it ourselves */
 395         *base = kzalloc(size + L1_CACHE_BYTES, flags);
 396         if (*base == NULL)
 397                 return NULL;
 398
 399         return (void *)L1_CACHE_ALIGN((u64)*base);
 400 }
 401
 402 /*
 403  * Setup the channel structures necessary to support XPartition Communication
 404  * between the specified remote partition and the local one.
 405  */
 406 static enum xp_retval
 407 xpc_setup_ch_structures(struct xpc_partition *part)
 408 {
 409         enum xp_retval ret;
 410         int ch_number;
 411         struct xpc_channel *ch;
 412         short partid = XPC_PARTID(part);
 413
 414         /*
 415          * Allocate all of the channel structures as a contiguous chunk of
 416          * memory.
 417          */
 418         DBUG_ON(part->channels != NULL);
 419         part->channels = kcalloc(XPC_MAX_NCHANNELS,
 420                                  sizeof(struct xpc_channel),
 421                                  GFP_KERNEL);
 422         if (part->channels == NULL) {
 423                 dev_err(xpc_chan, "can't get memory for channels\n");
 424                 return xpNoMemory;
 425         }
 426
 427         /* allocate the remote open and close args */
 428
 429         part->remote_openclose_args =
 430             xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
 431                                           GFP_KERNEL, &part->
 432                                           remote_openclose_args_base);
 433         if (part->remote_openclose_args == NULL) {
 434                 dev_err(xpc_chan, "can't get memory for remote connect args\n");
 435                 ret = xpNoMemory;
 436                 goto out_1;
 437         }
 438
 439         part->chctl.all_flags = 0;
 440         spin_lock_init(&part->chctl_lock);
 441
 442         atomic_set(&part->channel_mgr_requests, 1);
 443         init_waitqueue_head(&part->channel_mgr_wq);
 444
 445         part->nchannels = XPC_MAX_NCHANNELS;
 446
 447         atomic_set(&part->nchannels_active, 0);
 448         atomic_set(&part->nchannels_engaged, 0);
 449
 450         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 451                 ch = &part->channels[ch_number];
 452
 453                 ch->partid = partid;
 454                 ch->number = ch_number;
 455                 ch->flags = XPC_C_DISCONNECTED;
 456
 457                 atomic_set(&ch->kthreads_assigned, 0);
 458                 atomic_set(&ch->kthreads_idle, 0);
 459                 atomic_set(&ch->kthreads_active, 0);
 460
 461                 atomic_set(&ch->references, 0);
 462                 atomic_set(&ch->n_to_notify, 0);
 463
 464                 spin_lock_init(&ch->lock);
 465                 init_completion(&ch->wdisconnect_wait);
 466
 467                 atomic_set(&ch->n_on_msg_allocate_wq, 0);
 468                 init_waitqueue_head(&ch->msg_allocate_wq);
 469                 init_waitqueue_head(&ch->idle_wq);
 470         }
 471
 472         ret = xpc_arch_ops.setup_ch_structures(part);
 473         if (ret != xpSuccess)
 474                 goto out_2;
 475
 476         /*
 477          * With the setting of the partition setup_state to XPC_P_SS_SETUP,
 478          * we're declaring that this partition is ready to go.
 479          */
 480         part->setup_state = XPC_P_SS_SETUP;
 481
 482         return xpSuccess;
 483
 484         /* setup of ch structures failed */
 485 out_2:
 486         kfree(part->remote_openclose_args_base);
 487         part->remote_openclose_args = NULL;
 488 out_1:
 489         kfree(part->channels);
 490         part->channels = NULL;
 491         return ret;
 492 }
 493
 494 /*
 495  * Teardown the channel structures necessary to support XPartition Communication
 496  * between the specified remote partition and the local one.
 497  */
 498 static void
 499 xpc_teardown_ch_structures(struct xpc_partition *part)
 500 {
 501         DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
 502         DBUG_ON(atomic_read(&part->nchannels_active) != 0);
 503
 504         /*
 505          * Make this partition inaccessible to local processes by marking it
 506          * as no longer setup. Then wait before proceeding with the teardown
 507          * until all existing references cease.
 508          */
 509         DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
 510         part->setup_state = XPC_P_SS_WTEARDOWN;
 511
 512         wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
 513
 514         /* now we can begin tearing down the infrastructure */
 515
 516         xpc_arch_ops.teardown_ch_structures(part);
 517
 518         kfree(part->remote_openclose_args_base);
 519         part->remote_openclose_args = NULL;
 520         kfree(part->channels);
 521         part->channels = NULL;
 522
 523         part->setup_state = XPC_P_SS_TORNDOWN;
 524 }
 525
 526 /*
 527  * When XPC HB determines that a partition has come up, it will create a new
 528  * kthread and that kthread will call this function to attempt to set up the
 529  * basic infrastructure used for Cross Partition Communication with the newly
 530  * upped partition.
 531  *
 532  * The kthread that was created by XPC HB and which setup the XPC
 533  * infrastructure will remain assigned to the partition becoming the channel
 534  * manager for that partition until the partition is deactivating, at which
 535  * time the kthread will teardown the XPC infrastructure and then exit.
 536  */
 537 static int
 538 xpc_activating(void *__partid)
 539 {
 540         short partid = (u64)__partid;
 541         struct xpc_partition *part = &xpc_partitions[partid];
 542         unsigned long irq_flags;
 543
 544         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
 545
 546         spin_lock_irqsave(&part->act_lock, irq_flags);
 547
 548         if (part->act_state == XPC_P_AS_DEACTIVATING) {
 549                 part->act_state = XPC_P_AS_INACTIVE;
 550                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 551                 part->remote_rp_pa = 0;
 552                 return 0;
 553         }
 554
 555         /* indicate the thread is activating */
 556         DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
 557         part->act_state = XPC_P_AS_ACTIVATING;
 558
 559         XPC_SET_REASON(part, 0, 0);
 560         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 561
 562         dev_dbg(xpc_part, "activating partition %d\n", partid);
 563
 564         xpc_arch_ops.allow_hb(partid);
 565
 566         if (xpc_setup_ch_structures(part) == xpSuccess) {
 567                 (void)xpc_part_ref(part);       /* this will always succeed */
 568
 569                 if (xpc_arch_ops.make_first_contact(part) == xpSuccess) {
 570                         xpc_mark_partition_active(part);
 571                         xpc_channel_mgr(part);
 572                         /* won't return until partition is deactivating */
 573                 }
 574
 575                 xpc_part_deref(part);
 576                 xpc_teardown_ch_structures(part);
 577         }
 578
 579         xpc_arch_ops.disallow_hb(partid);
 580         xpc_mark_partition_inactive(part);
 581
 582         if (part->reason == xpReactivating) {
 583                 /* interrupting ourselves results in activating partition */
 584                 xpc_arch_ops.request_partition_reactivation(part);
 585         }
 586
 587         return 0;
 588 }
 589
 590 void
 591 xpc_activate_partition(struct xpc_partition *part)
 592 {
 593         short partid = XPC_PARTID(part);
 594         unsigned long irq_flags;
 595         struct task_struct *kthread;
 596
 597         spin_lock_irqsave(&part->act_lock, irq_flags);
 598
 599         DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
 600
 601         part->act_state = XPC_P_AS_ACTIVATION_REQ;
 602         XPC_SET_REASON(part, xpCloneKThread, __LINE__);
 603
 604         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 605
 606         kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
 607                               partid);
 608         if (IS_ERR(kthread)) {
 609                 spin_lock_irqsave(&part->act_lock, irq_flags);
 610                 part->act_state = XPC_P_AS_INACTIVE;
 611                 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
 612                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 613         }
 614 }
 615
 616 void
 617 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
 618 {
 619         int idle = atomic_read(&ch->kthreads_idle);
 620         int assigned = atomic_read(&ch->kthreads_assigned);
 621         int wakeup;
 622
 623         DBUG_ON(needed <= 0);
 624
 625         if (idle > 0) {
 626                 wakeup = (needed > idle) ? idle : needed;
 627                 needed -= wakeup;
 628
 629                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
 630                         "channel=%d\n", wakeup, ch->partid, ch->number);
 631
 632                 /* only wakeup the requested number of kthreads */
 633                 wake_up_nr(&ch->idle_wq, wakeup);
 634         }
 635
 636         if (needed <= 0)
 637                 return;
 638
 639         if (needed + assigned > ch->kthreads_assigned_limit) {
 640                 needed = ch->kthreads_assigned_limit - assigned;
 641                 if (needed <= 0)
 642                         return;
 643         }
 644
 645         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
 646                 needed, ch->partid, ch->number);
 647
 648         xpc_create_kthreads(ch, needed, 0);
 649 }
 650
 651 /*
 652  * This function is where XPC's kthreads wait for messages to deliver.
 653  */
 654 static void
 655 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
 656 {
 657         int (*n_of_deliverable_payloads) (struct xpc_channel *) =
 658                 xpc_arch_ops.n_of_deliverable_payloads;
 659
 660         do {
 661                 /* deliver messages to their intended recipients */
 662
 663                 while (n_of_deliverable_payloads(ch) > 0 &&
 664                        !(ch->flags & XPC_C_DISCONNECTING)) {
 665                         xpc_deliver_payload(ch);
 666                 }
 667
 668                 if (atomic_inc_return(&ch->kthreads_idle) >
 669                     ch->kthreads_idle_limit) {
 670                         /* too many idle kthreads on this channel */
 671                         atomic_dec(&ch->kthreads_idle);
 672                         break;
 673                 }
 674
 675                 dev_dbg(xpc_chan, "idle kthread calling "
 676                         "wait_event_interruptible_exclusive()\n");
 677
 678                 (void)wait_event_interruptible_exclusive(ch->idle_wq,
 679                                 (n_of_deliverable_payloads(ch) > 0 ||
 680                                  (ch->flags & XPC_C_DISCONNECTING)));
 681
 682                 atomic_dec(&ch->kthreads_idle);
 683
 684         } while (!(ch->flags & XPC_C_DISCONNECTING));
 685 }
 686
 687 static int
 688 xpc_kthread_start(void *args)
 689 {
 690         short partid = XPC_UNPACK_ARG1(args);
 691         u16 ch_number = XPC_UNPACK_ARG2(args);
 692         struct xpc_partition *part = &xpc_partitions[partid];
 693         struct xpc_channel *ch;
 694         int n_needed;
 695         unsigned long irq_flags;
 696         int (*n_of_deliverable_payloads) (struct xpc_channel *) =
 697                 xpc_arch_ops.n_of_deliverable_payloads;
 698
 699         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
 700                 partid, ch_number);
 701
 702         ch = &part->channels[ch_number];
 703
 704         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 705
 706                 /* let registerer know that connection has been established */
 707
 708                 spin_lock_irqsave(&ch->lock, irq_flags);
 709                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
 710                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
 711                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 712
 713                         xpc_connected_callout(ch);
 714
 715                         spin_lock_irqsave(&ch->lock, irq_flags);
 716                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
 717                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 718
 719                         /*
 720                          * It is possible that while the callout was being
 721                          * made that the remote partition sent some messages.
 722                          * If that is the case, we may need to activate
 723                          * additional kthreads to help deliver them. We only
 724                          * need one less than total #of messages to deliver.
 725                          */
 726                         n_needed = n_of_deliverable_payloads(ch) - 1;
 727                         if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
 728                                 xpc_activate_kthreads(ch, n_needed);
 729
 730                 } else {
 731                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 732                 }
 733
 734                 xpc_kthread_waitmsgs(part, ch);
 735         }
 736
 737         /* let registerer know that connection is disconnecting */
 738
 739         spin_lock_irqsave(&ch->lock, irq_flags);
 740         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 741             !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 742                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
 743                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 744
 745                 xpc_disconnect_callout(ch, xpDisconnecting);
 746
 747                 spin_lock_irqsave(&ch->lock, irq_flags);
 748                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
 749         }
 750         spin_unlock_irqrestore(&ch->lock, irq_flags);
 751
 752         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 753             atomic_dec_return(&part->nchannels_engaged) == 0) {
 754                 xpc_arch_ops.indicate_partition_disengaged(part);
 755         }
 756
 757         xpc_msgqueue_deref(ch);
 758
 759         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 760                 partid, ch_number);
 761
 762         xpc_part_deref(part);
 763         return 0;
 764 }
 765
 766 /*
 767  * For each partition that XPC has established communications with, there is
 768  * a minimum of one kernel thread assigned to perform any operation that
 769  * may potentially sleep or block (basically the callouts to the asynchronous
 770  * functions registered via xpc_connect()).
 771  *
 772  * Additional kthreads are created and destroyed by XPC as the workload
 773  * demands.
 774  *
 775  * A kthread is assigned to one of the active channels that exists for a given
 776  * partition.
 777  */
 778 void
 779 xpc_create_kthreads(struct xpc_channel *ch, int needed,
 780                     int ignore_disconnecting)
 781 {
 782         unsigned long irq_flags;
 783         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
 784         struct xpc_partition *part = &xpc_partitions[ch->partid];
 785         struct task_struct *kthread;
 786         void (*indicate_partition_disengaged) (struct xpc_partition *) =
 787                 xpc_arch_ops.indicate_partition_disengaged;
 788
 789         while (needed-- > 0) {
 790
 791                 /*
 792                  * The following is done on behalf of the newly created
 793                  * kthread. That kthread is responsible for doing the
 794                  * counterpart to the following before it exits.
 795                  */
 796                 if (ignore_disconnecting) {
 797                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
 798                                 /* kthreads assigned had gone to zero */
 799                                 BUG_ON(!(ch->flags &
 800                                          XPC_C_DISCONNECTINGCALLOUT_MADE));
 801                                 break;
 802                         }
 803
 804                 } else if (ch->flags & XPC_C_DISCONNECTING) {
 805                         break;
 806
 807                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
 808                            atomic_inc_return(&part->nchannels_engaged) == 1) {
 809                         xpc_arch_ops.indicate_partition_engaged(part);
 810                 }
 811                 (void)xpc_part_ref(part);
 812                 xpc_msgqueue_ref(ch);
 813
 814                 kthread = kthread_run(xpc_kthread_start, (void *)args,
 815                                       "xpc%02dc%d", ch->partid, ch->number);
 816                 if (IS_ERR(kthread)) {
 817                         /* the fork failed */
 818
 819                         /*
 820                          * NOTE: if (ignore_disconnecting &&
 821                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
 822                          * then we'll deadlock if all other kthreads assigned
 823                          * to this channel are blocked in the channel's
 824                          * registerer, because the only thing that will unblock
 825                          * them is the xpDisconnecting callout that this
 826                          * failed kthread_run() would have made.
 827                          */
 828
 829                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 830                             atomic_dec_return(&part->nchannels_engaged) == 0) {
 831                                 indicate_partition_disengaged(part);
 832                         }
 833                         xpc_msgqueue_deref(ch);
 834                         xpc_part_deref(part);
 835
 836                         if (atomic_read(&ch->kthreads_assigned) <
 837                             ch->kthreads_idle_limit) {
 838                                 /*
 839                                  * Flag this as an error only if we have an
 840                                  * insufficient #of kthreads for the channel
 841                                  * to function.
 842                                  */
 843                                 spin_lock_irqsave(&ch->lock, irq_flags);
 844                                 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
 845                                                        &irq_flags);
 846                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 847                         }
 848                         break;
 849                 }
 850         }
 851 }
 852
 853 void
 854 xpc_disconnect_wait(int ch_number)
 855 {
 856         unsigned long irq_flags;
 857         short partid;
 858         struct xpc_partition *part;
 859         struct xpc_channel *ch;
 860         int wakeup_channel_mgr;
 861
 862         /* now wait for all callouts to the caller's function to cease */
 863         for (partid = 0; partid < xp_max_npartitions; partid++) {
 864                 part = &xpc_partitions[partid];
 865
 866                 if (!xpc_part_ref(part))
 867                         continue;
 868
 869                 ch = &part->channels[ch_number];
 870
 871                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
 872                         xpc_part_deref(part);
 873                         continue;
 874                 }
 875
 876                 wait_for_completion(&ch->wdisconnect_wait);
 877
 878                 spin_lock_irqsave(&ch->lock, irq_flags);
 879                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 880                 wakeup_channel_mgr = 0;
 881
 882                 if (ch->delayed_chctl_flags) {
 883                         if (part->act_state != XPC_P_AS_DEACTIVATING) {
 884                                 spin_lock(&part->chctl_lock);
 885                                 part->chctl.flags[ch->number] |=
 886                                     ch->delayed_chctl_flags;
 887                                 spin_unlock(&part->chctl_lock);
 888                                 wakeup_channel_mgr = 1;
 889                         }
 890                         ch->delayed_chctl_flags = 0;
 891                 }
 892
 893                 ch->flags &= ~XPC_C_WDISCONNECT;
 894                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 895
 896                 if (wakeup_channel_mgr)
 897                         xpc_wakeup_channel_mgr(part);
 898
 899                 xpc_part_deref(part);
 900         }
 901 }
 902
 903 static int
 904 xpc_setup_partitions(void)
 905 {
 906         short partid;
 907         struct xpc_partition *part;
 908
 909         xpc_partitions = kcalloc(xp_max_npartitions,
 910                                  sizeof(struct xpc_partition),
 911                                  GFP_KERNEL);
 912         if (xpc_partitions == NULL) {
 913                 dev_err(xpc_part, "can't get memory for partition structure\n");
 914                 return -ENOMEM;
 915         }
 916
 917         /*
 918          * The first few fields of each entry of xpc_partitions[] need to
 919          * be initialized now so that calls to xpc_connect() and
 920          * xpc_disconnect() can be made prior to the activation of any remote
 921          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
 922          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
 923          * PARTITION HAS BEEN ACTIVATED.
 924          */
 925         for (partid = 0; partid < xp_max_npartitions; partid++) {
 926                 part = &xpc_partitions[partid];
 927
 928                 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
 929
 930                 part->activate_IRQ_rcvd = 0;
 931                 spin_lock_init(&part->act_lock);
 932                 part->act_state = XPC_P_AS_INACTIVE;
 933                 XPC_SET_REASON(part, 0, 0);
 934
 935                 timer_setup(&part->disengage_timer,
 936                             xpc_timeout_partition_disengage, 0);
 937
 938                 part->setup_state = XPC_P_SS_UNSET;
 939                 init_waitqueue_head(&part->teardown_wq);
 940                 atomic_set(&part->references, 0);
 941         }
 942
 943         return xpc_arch_ops.setup_partitions();
 944 }
 945
 946 static void
 947 xpc_teardown_partitions(void)
 948 {
 949         xpc_arch_ops.teardown_partitions();
 950         kfree(xpc_partitions);
 951 }
 952
 953 static void
 954 xpc_do_exit(enum xp_retval reason)
 955 {
 956         short partid;
 957         int active_part_count, printed_waiting_msg = 0;
 958         struct xpc_partition *part;
 959         unsigned long printmsg_time, disengage_timeout = 0;
 960
 961         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 962         DBUG_ON(xpc_exiting == 1);
 963
 964         /*
 965          * Let the heartbeat checker thread and the discovery thread
 966          * (if one is running) know that they should exit. Also wake up
 967          * the heartbeat checker thread in case it's sleeping.
 968          */
 969         xpc_exiting = 1;
 970         wake_up_interruptible(&xpc_activate_IRQ_wq);
 971
 972         /* wait for the discovery thread to exit */
 973         wait_for_completion(&xpc_discovery_exited);
 974
 975         /* wait for the heartbeat checker thread to exit */
 976         wait_for_completion(&xpc_hb_checker_exited);
 977
 978         /* sleep for a 1/3 of a second or so */
 979         (void)msleep_interruptible(300);
 980
 981         /* wait for all partitions to become inactive */
 982
 983         printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
 984         xpc_disengage_timedout = 0;
 985
 986         do {
 987                 active_part_count = 0;
 988
 989                 for (partid = 0; partid < xp_max_npartitions; partid++) {
 990                         part = &xpc_partitions[partid];
 991
 992                         if (xpc_partition_disengaged(part) &&
 993                             part->act_state == XPC_P_AS_INACTIVE) {
 994                                 continue;
 995                         }
 996
 997                         active_part_count++;
 998
 999                         XPC_DEACTIVATE_PARTITION(part, reason);
1000
1001                         if (part->disengage_timeout > disengage_timeout)
1002                                 disengage_timeout = part->disengage_timeout;
1003                 }
1004
1005                 if (xpc_arch_ops.any_partition_engaged()) {
1006                         if (time_is_before_jiffies(printmsg_time)) {
1007                                 dev_info(xpc_part, "waiting for remote "
1008                                          "partitions to deactivate, timeout in "
1009                                          "%ld seconds\n", (disengage_timeout -
1010                                          jiffies) / HZ);
1011                                 printmsg_time = jiffies +
1012                                     (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1013                                 printed_waiting_msg = 1;
1014                         }
1015
1016                 } else if (active_part_count > 0) {
1017                         if (printed_waiting_msg) {
1018                                 dev_info(xpc_part, "waiting for local partition"
1019                                          " to deactivate\n");
1020                                 printed_waiting_msg = 0;
1021                         }
1022
1023                 } else {
1024                         if (!xpc_disengage_timedout) {
1025                                 dev_info(xpc_part, "all partitions have "
1026                                          "deactivated\n");
1027                         }
1028                         break;
1029                 }
1030
1031                 /* sleep for a 1/3 of a second or so */
1032                 (void)msleep_interruptible(300);
1033
1034         } while (1);
1035
1036         DBUG_ON(xpc_arch_ops.any_partition_engaged());
1037
1038         xpc_teardown_rsvd_page();
1039
1040         if (reason == xpUnloading) {
1041                 (void)unregister_die_notifier(&xpc_die_notifier);
1042                 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1043         }
1044
1045         /* clear the interface to XPC's functions */
1046         xpc_clear_interface();
1047
1048         if (xpc_sysctl)
1049                 unregister_sysctl_table(xpc_sysctl);
1050
1051         xpc_teardown_partitions();
1052
1053         if (is_shub())
1054                 xpc_exit_sn2();
1055         else if (is_uv())
1056                 xpc_exit_uv();
1057 }
1058
1059 /*
1060  * This function is called when the system is being rebooted.
1061  */
1062 static int
1063 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1064 {
1065         enum xp_retval reason;
1066
1067         switch (event) {
1068         case SYS_RESTART:
1069                 reason = xpSystemReboot;
1070                 break;
1071         case SYS_HALT:
1072                 reason = xpSystemHalt;
1073                 break;
1074         case SYS_POWER_OFF:
1075                 reason = xpSystemPoweroff;
1076                 break;
1077         default:
1078                 reason = xpSystemGoingDown;
1079         }
1080
1081         xpc_do_exit(reason);
1082         return NOTIFY_DONE;
1083 }
1084
1085 /* Used to only allow one cpu to complete disconnect */
1086 static unsigned int xpc_die_disconnecting;
1087
1088 /*
1089  * Notify other partitions to deactivate from us by first disengaging from all
1090  * references to our memory.
1091  */
1092 static void
1093 xpc_die_deactivate(void)
1094 {
1095         struct xpc_partition *part;
1096         short partid;
1097         int any_engaged;
1098         long keep_waiting;
1099         long wait_to_print;
1100
1101         if (cmpxchg(&xpc_die_disconnecting, 0, 1))
1102                 return;
1103
1104         /* keep xpc_hb_checker thread from doing anything (just in case) */
1105         xpc_exiting = 1;
1106
1107         xpc_arch_ops.disallow_all_hbs();   /*indicate we're deactivated */
1108
1109         for (partid = 0; partid < xp_max_npartitions; partid++) {
1110                 part = &xpc_partitions[partid];
1111
1112                 if (xpc_arch_ops.partition_engaged(partid) ||
1113                     part->act_state != XPC_P_AS_INACTIVE) {
1114                         xpc_arch_ops.request_partition_deactivation(part);
1115                         xpc_arch_ops.indicate_partition_disengaged(part);
1116                 }
1117         }
1118
1119         /*
1120          * Though we requested that all other partitions deactivate from us,
1121          * we only wait until they've all disengaged or we've reached the
1122          * defined timelimit.
1123          *
1124          * Given that one iteration through the following while-loop takes
1125          * approximately 200 microseconds, calculate the #of loops to take
1126          * before bailing and the #of loops before printing a waiting message.
1127          */
1128         keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1129         wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1130
1131         while (1) {
1132                 any_engaged = xpc_arch_ops.any_partition_engaged();
1133                 if (!any_engaged) {
1134                         dev_info(xpc_part, "all partitions have deactivated\n");
1135                         break;
1136                 }
1137
1138                 if (!keep_waiting--) {
1139                         for (partid = 0; partid < xp_max_npartitions;
1140                              partid++) {
1141                                 if (xpc_arch_ops.partition_engaged(partid)) {
1142                                         dev_info(xpc_part, "deactivate from "
1143                                                  "remote partition %d timed "
1144                                                  "out\n", partid);
1145                                 }
1146                         }
1147                         break;
1148                 }
1149
1150                 if (!wait_to_print--) {
1151                         dev_info(xpc_part, "waiting for remote partitions to "
1152                                  "deactivate, timeout in %ld seconds\n",
1153                                  keep_waiting / (1000 * 5));
1154                         wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1155                             1000 * 5;
1156                 }
1157
1158                 udelay(200);
1159         }
1160 }
1161
1162 /*
1163  * This function is called when the system is being restarted or halted due
1164  * to some sort of system failure. If this is the case we need to notify the
1165  * other partitions to disengage from all references to our memory.
1166  * This function can also be called when our heartbeater could be offlined
1167  * for a time. In this case we need to notify other partitions to not worry
1168  * about the lack of a heartbeat.
1169  */
1170 static int
1171 xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args)
1172 {
1173 #ifdef CONFIG_IA64              /* !!! temporary kludge */
1174         switch (event) {
1175         case DIE_MACHINE_RESTART:
1176         case DIE_MACHINE_HALT:
1177                 xpc_die_deactivate();
1178                 break;
1179
1180         case DIE_KDEBUG_ENTER:
1181                 /* Should lack of heartbeat be ignored by other partitions? */
1182                 if (!xpc_kdebug_ignore)
1183                         break;
1184
1185                 /* fall through */
1186         case DIE_MCA_MONARCH_ENTER:
1187         case DIE_INIT_MONARCH_ENTER:
1188                 xpc_arch_ops.offline_heartbeat();
1189                 break;
1190
1191         case DIE_KDEBUG_LEAVE:
1192                 /* Is lack of heartbeat being ignored by other partitions? */
1193                 if (!xpc_kdebug_ignore)
1194                         break;
1195
1196                 /* fall through */
1197         case DIE_MCA_MONARCH_LEAVE:
1198         case DIE_INIT_MONARCH_LEAVE:
1199                 xpc_arch_ops.online_heartbeat();
1200                 break;
1201         }
1202 #else
1203         struct die_args *die_args = _die_args;
1204
1205         switch (event) {
1206         case DIE_TRAP:
1207                 if (die_args->trapnr == X86_TRAP_DF)
1208                         xpc_die_deactivate();
1209
1210                 if (((die_args->trapnr == X86_TRAP_MF) ||
1211                      (die_args->trapnr == X86_TRAP_XF)) &&
1212                     !user_mode(die_args->regs))
1213                         xpc_die_deactivate();
1214
1215                 break;
1216         case DIE_INT3:
1217         case DIE_DEBUG:
1218                 break;
1219         case DIE_OOPS:
1220         case DIE_GPF:
1221         default:
1222                 xpc_die_deactivate();
1223         }
1224 #endif
1225
1226         return NOTIFY_DONE;
1227 }
1228
1229 int __init
1230 xpc_init(void)
1231 {
1232         int ret;
1233         struct task_struct *kthread;
1234
1235         dev_set_name(xpc_part, "part");
1236         dev_set_name(xpc_chan, "chan");
1237
1238         if (is_shub()) {
1239                 /*
1240                  * The ia64-sn2 architecture supports at most 64 partitions.
1241                  * And the inability to unregister remote amos restricts us
1242                  * further to only support exactly 64 partitions on this
1243                  * architecture, no less.
1244                  */
1245                 if (xp_max_npartitions != 64) {
1246                         dev_err(xpc_part, "max #of partitions not set to 64\n");
1247                         ret = -EINVAL;
1248                 } else {
1249                         ret = xpc_init_sn2();
1250                 }
1251
1252         } else if (is_uv()) {
1253                 ret = xpc_init_uv();
1254
1255         } else {
1256                 ret = -ENODEV;
1257         }
1258
1259         if (ret != 0)
1260                 return ret;
1261
1262         ret = xpc_setup_partitions();
1263         if (ret != 0) {
1264                 dev_err(xpc_part, "can't get memory for partition structure\n");
1265                 goto out_1;
1266         }
1267
1268         xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1269
1270         /*
1271          * Fill the partition reserved page with the information needed by
1272          * other partitions to discover we are alive and establish initial
1273          * communications.
1274          */
1275         ret = xpc_setup_rsvd_page();
1276         if (ret != 0) {
1277                 dev_err(xpc_part, "can't setup our reserved page\n");
1278                 goto out_2;
1279         }
1280
1281         /* add ourselves to the reboot_notifier_list */
1282         ret = register_reboot_notifier(&xpc_reboot_notifier);
1283         if (ret != 0)
1284                 dev_warn(xpc_part, "can't register reboot notifier\n");
1285
1286         /* add ourselves to the die_notifier list */
1287         ret = register_die_notifier(&xpc_die_notifier);
1288         if (ret != 0)
1289                 dev_warn(xpc_part, "can't register die notifier\n");
1290
1291         /*
1292          * The real work-horse behind xpc.  This processes incoming
1293          * interrupts and monitors remote heartbeats.
1294          */
1295         kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1296         if (IS_ERR(kthread)) {
1297                 dev_err(xpc_part, "failed while forking hb check thread\n");
1298                 ret = -EBUSY;
1299                 goto out_3;
1300         }
1301
1302         /*
1303          * Startup a thread that will attempt to discover other partitions to
1304          * activate based on info provided by SAL. This new thread is short
1305          * lived and will exit once discovery is complete.
1306          */
1307         kthread = kthread_run(xpc_initiate_discovery, NULL,
1308                               XPC_DISCOVERY_THREAD_NAME);
1309         if (IS_ERR(kthread)) {
1310                 dev_err(xpc_part, "failed while forking discovery thread\n");
1311
1312                 /* mark this new thread as a non-starter */
1313                 complete(&xpc_discovery_exited);
1314
1315                 xpc_do_exit(xpUnloading);
1316                 return -EBUSY;
1317         }
1318
1319         /* set the interface to point at XPC's functions */
1320         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1321                           xpc_initiate_send, xpc_initiate_send_notify,
1322                           xpc_initiate_received, xpc_initiate_partid_to_nasids);
1323
1324         return 0;
1325
1326         /* initialization was not successful */
1327 out_3:
1328         xpc_teardown_rsvd_page();
1329
1330         (void)unregister_die_notifier(&xpc_die_notifier);
1331         (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1332 out_2:
1333         if (xpc_sysctl)
1334                 unregister_sysctl_table(xpc_sysctl);
1335
1336         xpc_teardown_partitions();
1337 out_1:
1338         if (is_shub())
1339                 xpc_exit_sn2();
1340         else if (is_uv())
1341                 xpc_exit_uv();
1342         return ret;
1343 }
1344
1345 module_init(xpc_init);
1346
1347 void __exit
1348 xpc_exit(void)
1349 {
1350         xpc_do_exit(xpUnloading);
1351 }
1352
1353 module_exit(xpc_exit);
1354
1355 MODULE_AUTHOR("Silicon Graphics, Inc.");
1356 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1357 MODULE_LICENSE("GPL");
1358
1359 module_param(xpc_hb_interval, int, 0);
1360 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1361                  "heartbeat increments.");
1362
1363 module_param(xpc_hb_check_interval, int, 0);
1364 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1365                  "heartbeat checks.");
1366
1367 module_param(xpc_disengage_timelimit, int, 0);
1368 MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1369                  "for disengage to complete.");
1370
1371 module_param(xpc_kdebug_ignore, int, 0);
1372 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1373                  "other partitions when dropping into kdebug.");