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   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) 2004-2006 Silicon Graphics, Inc.  All Rights Reserved.
   7  */
   8
   9
  10 /*
  11  * Cross Partition Communication (XPC) support - standard version.
  12  *
  13  *      XPC provides a message passing capability that crosses partition
  14  *      boundaries. This module is made up of two parts:
  15  *
  16  *          partition   This part detects the presence/absence of other
  17  *                      partitions. It provides a heartbeat and monitors
  18  *                      the heartbeats of other partitions.
  19  *
  20  *          channel     This part manages the channels and sends/receives
  21  *                      messages across them to/from other partitions.
  22  *
  23  *      There are a couple of additional functions residing in XP, which
  24  *      provide an interface to XPC for its users.
  25  *
  26  *
  27  *      Caveats:
  28  *
  29  *        . We currently have no way to determine which nasid an IPI came
  30  *          from. Thus, xpc_IPI_send() does a remote AMO write followed by
  31  *          an IPI. The AMO indicates where data is to be pulled from, so
  32  *          after the IPI arrives, the remote partition checks the AMO word.
  33  *          The IPI can actually arrive before the AMO however, so other code
  34  *          must periodically check for this case. Also, remote AMO operations
  35  *          do not reliably time out. Thus we do a remote PIO read solely to
  36  *          know whether the remote partition is down and whether we should
  37  *          stop sending IPIs to it. This remote PIO read operation is set up
  38  *          in a special nofault region so SAL knows to ignore (and cleanup)
  39  *          any errors due to the remote AMO write, PIO read, and/or PIO
  40  *          write operations.
  41  *
  42  *          If/when new hardware solves this IPI problem, we should abandon
  43  *          the current approach.
  44  *
  45  */
  46
  47
  48 #include <linux/kernel.h>
  49 #include <linux/module.h>
  50 #include <linux/init.h>
  51 #include <linux/sched.h>
  52 #include <linux/syscalls.h>
  53 #include <linux/cache.h>
  54 #include <linux/interrupt.h>
  55 #include <linux/slab.h>
  56 #include <linux/delay.h>
  57 #include <linux/reboot.h>
  58 #include <linux/completion.h>
  59 #include <asm/sn/intr.h>
  60 #include <asm/sn/sn_sal.h>
  61 #include <asm/kdebug.h>
  62 #include <asm/uaccess.h>
  63 #include <asm/sn/xpc.h>
  64
  65
  66 /* define two XPC debug device structures to be used with dev_dbg() et al */
  67
  68 struct device_driver xpc_dbg_name = {
  69         .name = "xpc"
  70 };
  71
  72 struct device xpc_part_dbg_subname = {
  73         .bus_id = {0},          /* set to "part" at xpc_init() time */
  74         .driver = &xpc_dbg_name
  75 };
  76
  77 struct device xpc_chan_dbg_subname = {
  78         .bus_id = {0},          /* set to "chan" at xpc_init() time */
  79         .driver = &xpc_dbg_name
  80 };
  81
  82 struct device *xpc_part = &xpc_part_dbg_subname;
  83 struct device *xpc_chan = &xpc_chan_dbg_subname;
  84
  85
  86 static int xpc_kdebug_ignore;
  87
  88
  89 /* systune related variables for /proc/sys directories */
  90
  91 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
  92 static int xpc_hb_min_interval = 1;
  93 static int xpc_hb_max_interval = 10;
  94
  95 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
  96 static int xpc_hb_check_min_interval = 10;
  97 static int xpc_hb_check_max_interval = 120;
  98
  99 int xpc_disengage_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
 100 static int xpc_disengage_request_min_timelimit = 0;
 101 static int xpc_disengage_request_max_timelimit = 120;
 102
 103 static ctl_table xpc_sys_xpc_hb_dir[] = {
 104         {
 105                 1,
 106                 "hb_interval",
 107                 &xpc_hb_interval,
 108                 sizeof(int),
 109                 0644,
 110                 NULL,
 111                 &proc_dointvec_minmax,
 112                 &sysctl_intvec,
 113                 NULL,
 114                 &xpc_hb_min_interval,
 115                 &xpc_hb_max_interval
 116         },
 117         {
 118                 2,
 119                 "hb_check_interval",
 120                 &xpc_hb_check_interval,
 121                 sizeof(int),
 122                 0644,
 123                 NULL,
 124                 &proc_dointvec_minmax,
 125                 &sysctl_intvec,
 126                 NULL,
 127                 &xpc_hb_check_min_interval,
 128                 &xpc_hb_check_max_interval
 129         },
 130         {0}
 131 };
 132 static ctl_table xpc_sys_xpc_dir[] = {
 133         {
 134                 1,
 135                 "hb",
 136                 NULL,
 137                 0,
 138                 0555,
 139                 xpc_sys_xpc_hb_dir
 140         },
 141         {
 142                 2,
 143                 "disengage_request_timelimit",
 144                 &xpc_disengage_request_timelimit,
 145                 sizeof(int),
 146                 0644,
 147                 NULL,
 148                 &proc_dointvec_minmax,
 149                 &sysctl_intvec,
 150                 NULL,
 151                 &xpc_disengage_request_min_timelimit,
 152                 &xpc_disengage_request_max_timelimit
 153         },
 154         {0}
 155 };
 156 static ctl_table xpc_sys_dir[] = {
 157         {
 158                 1,
 159                 "xpc",
 160                 NULL,
 161                 0,
 162                 0555,
 163                 xpc_sys_xpc_dir
 164         },
 165         {0}
 166 };
 167 static struct ctl_table_header *xpc_sysctl;
 168
 169 /* non-zero if any remote partition disengage request was timed out */
 170 int xpc_disengage_request_timedout;
 171
 172 /* #of IRQs received */
 173 static atomic_t xpc_act_IRQ_rcvd;
 174
 175 /* IRQ handler notifies this wait queue on receipt of an IRQ */
 176 static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
 177
 178 static unsigned long xpc_hb_check_timeout;
 179
 180 /* notification that the xpc_hb_checker thread has exited */
 181 static DECLARE_COMPLETION(xpc_hb_checker_exited);
 182
 183 /* notification that the xpc_discovery thread has exited */
 184 static DECLARE_COMPLETION(xpc_discovery_exited);
 185
 186
 187 static struct timer_list xpc_hb_timer;
 188
 189
 190 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
 191
 192
 193 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
 194 static struct notifier_block xpc_reboot_notifier = {
 195         .notifier_call = xpc_system_reboot,
 196 };
 197
 198 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
 199 static struct notifier_block xpc_die_notifier = {
 200         .notifier_call = xpc_system_die,
 201 };
 202
 203
 204 /*
 205  * Timer function to enforce the timelimit on the partition disengage request.
 206  */
 207 static void
 208 xpc_timeout_partition_disengage_request(unsigned long data)
 209 {
 210         struct xpc_partition *part = (struct xpc_partition *) data;
 211
 212
 213         DBUG_ON(jiffies < part->disengage_request_timeout);
 214
 215         (void) xpc_partition_disengaged(part);
 216
 217         DBUG_ON(part->disengage_request_timeout != 0);
 218         DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
 219 }
 220
 221
 222 /*
 223  * Notify the heartbeat check thread that an IRQ has been received.
 224  */
 225 static irqreturn_t
 226 xpc_act_IRQ_handler(int irq, void *dev_id, struct pt_regs *regs)
 227 {
 228         atomic_inc(&xpc_act_IRQ_rcvd);
 229         wake_up_interruptible(&xpc_act_IRQ_wq);
 230         return IRQ_HANDLED;
 231 }
 232
 233
 234 /*
 235  * Timer to produce the heartbeat.  The timer structures function is
 236  * already set when this is initially called.  A tunable is used to
 237  * specify when the next timeout should occur.
 238  */
 239 static void
 240 xpc_hb_beater(unsigned long dummy)
 241 {
 242         xpc_vars->heartbeat++;
 243
 244         if (jiffies >= xpc_hb_check_timeout) {
 245                 wake_up_interruptible(&xpc_act_IRQ_wq);
 246         }
 247
 248         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
 249         add_timer(&xpc_hb_timer);
 250 }
 251
 252
 253 /*
 254  * This thread is responsible for nearly all of the partition
 255  * activation/deactivation.
 256  */
 257 static int
 258 xpc_hb_checker(void *ignore)
 259 {
 260         int last_IRQ_count = 0;
 261         int new_IRQ_count;
 262         int force_IRQ=0;
 263
 264
 265         /* this thread was marked active by xpc_hb_init() */
 266
 267         daemonize(XPC_HB_CHECK_THREAD_NAME);
 268
 269         set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
 270
 271         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
 272
 273         while (!(volatile int) xpc_exiting) {
 274
 275                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
 276                         "been received\n",
 277                         (int) (xpc_hb_check_timeout - jiffies),
 278                         atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
 279
 280
 281                 /* checking of remote heartbeats is skewed by IRQ handling */
 282                 if (jiffies >= xpc_hb_check_timeout) {
 283                         dev_dbg(xpc_part, "checking remote heartbeats\n");
 284                         xpc_check_remote_hb();
 285
 286                         /*
 287                          * We need to periodically recheck to ensure no
 288                          * IPI/AMO pairs have been missed.  That check
 289                          * must always reset xpc_hb_check_timeout.
 290                          */
 291                         force_IRQ = 1;
 292                 }
 293
 294
 295                 /* check for outstanding IRQs */
 296                 new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
 297                 if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
 298                         force_IRQ = 0;
 299
 300                         dev_dbg(xpc_part, "found an IRQ to process; will be "
 301                                 "resetting xpc_hb_check_timeout\n");
 302
 303                         last_IRQ_count += xpc_identify_act_IRQ_sender();
 304                         if (last_IRQ_count < new_IRQ_count) {
 305                                 /* retry once to help avoid missing AMO */
 306                                 (void) xpc_identify_act_IRQ_sender();
 307                         }
 308                         last_IRQ_count = new_IRQ_count;
 309
 310                         xpc_hb_check_timeout = jiffies +
 311                                            (xpc_hb_check_interval * HZ);
 312                 }
 313
 314                 /* wait for IRQ or timeout */
 315                 (void) wait_event_interruptible(xpc_act_IRQ_wq,
 316                             (last_IRQ_count < atomic_read(&xpc_act_IRQ_rcvd) ||
 317                                         jiffies >= xpc_hb_check_timeout ||
 318                                                 (volatile int) xpc_exiting));
 319         }
 320
 321         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 322
 323
 324         /* mark this thread as having exited */
 325         complete(&xpc_hb_checker_exited);
 326         return 0;
 327 }
 328
 329
 330 /*
 331  * This thread will attempt to discover other partitions to activate
 332  * based on info provided by SAL. This new thread is short lived and
 333  * will exit once discovery is complete.
 334  */
 335 static int
 336 xpc_initiate_discovery(void *ignore)
 337 {
 338         daemonize(XPC_DISCOVERY_THREAD_NAME);
 339
 340         xpc_discovery();
 341
 342         dev_dbg(xpc_part, "discovery thread is exiting\n");
 343
 344         /* mark this thread as having exited */
 345         complete(&xpc_discovery_exited);
 346         return 0;
 347 }
 348
 349
 350 /*
 351  * Establish first contact with the remote partititon. This involves pulling
 352  * the XPC per partition variables from the remote partition and waiting for
 353  * the remote partition to pull ours.
 354  */
 355 static enum xpc_retval
 356 xpc_make_first_contact(struct xpc_partition *part)
 357 {
 358         enum xpc_retval ret;
 359
 360
 361         while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
 362                 if (ret != xpcRetry) {
 363                         XPC_DEACTIVATE_PARTITION(part, ret);
 364                         return ret;
 365                 }
 366
 367                 dev_dbg(xpc_chan, "waiting to make first contact with "
 368                         "partition %d\n", XPC_PARTID(part));
 369
 370                 /* wait a 1/4 of a second or so */
 371                 (void) msleep_interruptible(250);
 372
 373                 if (part->act_state == XPC_P_DEACTIVATING) {
 374                         return part->reason;
 375                 }
 376         }
 377
 378         return xpc_mark_partition_active(part);
 379 }
 380
 381
 382 /*
 383  * The first kthread assigned to a newly activated partition is the one
 384  * created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
 385  * that kthread until the partition is brought down, at which time that kthread
 386  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
 387  * that XPC has dismantled all communication infrastructure for the associated
 388  * partition.) This kthread becomes the channel manager for that partition.
 389  *
 390  * Each active partition has a channel manager, who, besides connecting and
 391  * disconnecting channels, will ensure that each of the partition's connected
 392  * channels has the required number of assigned kthreads to get the work done.
 393  */
 394 static void
 395 xpc_channel_mgr(struct xpc_partition *part)
 396 {
 397         while (part->act_state != XPC_P_DEACTIVATING ||
 398                         atomic_read(&part->nchannels_active) > 0 ||
 399                                         !xpc_partition_disengaged(part)) {
 400
 401                 xpc_process_channel_activity(part);
 402
 403
 404                 /*
 405                  * Wait until we've been requested to activate kthreads or
 406                  * all of the channel's message queues have been torn down or
 407                  * a signal is pending.
 408                  *
 409                  * The channel_mgr_requests is set to 1 after being awakened,
 410                  * This is done to prevent the channel mgr from making one pass
 411                  * through the loop for each request, since he will
 412                  * be servicing all the requests in one pass. The reason it's
 413                  * set to 1 instead of 0 is so that other kthreads will know
 414                  * that the channel mgr is running and won't bother trying to
 415                  * wake him up.
 416                  */
 417                 atomic_dec(&part->channel_mgr_requests);
 418                 (void) wait_event_interruptible(part->channel_mgr_wq,
 419                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
 420                                 (volatile u64) part->local_IPI_amo != 0 ||
 421                                 ((volatile u8) part->act_state ==
 422                                                         XPC_P_DEACTIVATING &&
 423                                 atomic_read(&part->nchannels_active) == 0 &&
 424                                 xpc_partition_disengaged(part))));
 425                 atomic_set(&part->channel_mgr_requests, 1);
 426
 427                 // >>> Does it need to wakeup periodically as well? In case we
 428                 // >>> miscalculated the #of kthreads to wakeup or create?
 429         }
 430 }
 431
 432
 433 /*
 434  * When XPC HB determines that a partition has come up, it will create a new
 435  * kthread and that kthread will call this function to attempt to set up the
 436  * basic infrastructure used for Cross Partition Communication with the newly
 437  * upped partition.
 438  *
 439  * The kthread that was created by XPC HB and which setup the XPC
 440  * infrastructure will remain assigned to the partition until the partition
 441  * goes down. At which time the kthread will teardown the XPC infrastructure
 442  * and then exit.
 443  *
 444  * XPC HB will put the remote partition's XPC per partition specific variables
 445  * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
 446  * calling xpc_partition_up().
 447  */
 448 static void
 449 xpc_partition_up(struct xpc_partition *part)
 450 {
 451         DBUG_ON(part->channels != NULL);
 452
 453         dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
 454
 455         if (xpc_setup_infrastructure(part) != xpcSuccess) {
 456                 return;
 457         }
 458
 459         /*
 460          * The kthread that XPC HB called us with will become the
 461          * channel manager for this partition. It will not return
 462          * back to XPC HB until the partition's XPC infrastructure
 463          * has been dismantled.
 464          */
 465
 466         (void) xpc_part_ref(part);      /* this will always succeed */
 467
 468         if (xpc_make_first_contact(part) == xpcSuccess) {
 469                 xpc_channel_mgr(part);
 470         }
 471
 472         xpc_part_deref(part);
 473
 474         xpc_teardown_infrastructure(part);
 475 }
 476
 477
 478 static int
 479 xpc_activating(void *__partid)
 480 {
 481         partid_t partid = (u64) __partid;
 482         struct xpc_partition *part = &xpc_partitions[partid];
 483         unsigned long irq_flags;
 484         struct sched_param param = { sched_priority: MAX_RT_PRIO - 1 };
 485         int ret;
 486
 487
 488         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 489
 490         spin_lock_irqsave(&part->act_lock, irq_flags);
 491
 492         if (part->act_state == XPC_P_DEACTIVATING) {
 493                 part->act_state = XPC_P_INACTIVE;
 494                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 495                 part->remote_rp_pa = 0;
 496                 return 0;
 497         }
 498
 499         /* indicate the thread is activating */
 500         DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
 501         part->act_state = XPC_P_ACTIVATING;
 502
 503         XPC_SET_REASON(part, 0, 0);
 504         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 505
 506         dev_dbg(xpc_part, "bringing partition %d up\n", partid);
 507
 508         daemonize("xpc%02d", partid);
 509
 510         /*
 511          * This thread needs to run at a realtime priority to prevent a
 512          * significant performance degradation.
 513          */
 514         ret = sched_setscheduler(current, SCHED_FIFO, &param);
 515         if (ret != 0) {
 516                 dev_warn(xpc_part, "unable to set pid %d to a realtime "
 517                         "priority, ret=%d\n", current->pid, ret);
 518         }
 519
 520         /* allow this thread and its children to run on any CPU */
 521         set_cpus_allowed(current, CPU_MASK_ALL);
 522
 523         /*
 524          * Register the remote partition's AMOs with SAL so it can handle
 525          * and cleanup errors within that address range should the remote
 526          * partition go down. We don't unregister this range because it is
 527          * difficult to tell when outstanding writes to the remote partition
 528          * are finished and thus when it is safe to unregister. This should
 529          * not result in wasted space in the SAL xp_addr_region table because
 530          * we should get the same page for remote_amos_page_pa after module
 531          * reloads and system reboots.
 532          */
 533         if (sn_register_xp_addr_region(part->remote_amos_page_pa,
 534                                                         PAGE_SIZE, 1) < 0) {
 535                 dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
 536                         "xp_addr region\n", partid);
 537
 538                 spin_lock_irqsave(&part->act_lock, irq_flags);
 539                 part->act_state = XPC_P_INACTIVE;
 540                 XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
 541                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 542                 part->remote_rp_pa = 0;
 543                 return 0;
 544         }
 545
 546         xpc_allow_hb(partid, xpc_vars);
 547         xpc_IPI_send_activated(part);
 548
 549
 550         /*
 551          * xpc_partition_up() holds this thread and marks this partition as
 552          * XPC_P_ACTIVE by calling xpc_hb_mark_active().
 553          */
 554         (void) xpc_partition_up(part);
 555
 556         xpc_disallow_hb(partid, xpc_vars);
 557         xpc_mark_partition_inactive(part);
 558
 559         if (part->reason == xpcReactivating) {
 560                 /* interrupting ourselves results in activating partition */
 561                 xpc_IPI_send_reactivate(part);
 562         }
 563
 564         return 0;
 565 }
 566
 567
 568 void
 569 xpc_activate_partition(struct xpc_partition *part)
 570 {
 571         partid_t partid = XPC_PARTID(part);
 572         unsigned long irq_flags;
 573         pid_t pid;
 574
 575
 576         spin_lock_irqsave(&part->act_lock, irq_flags);
 577
 578         DBUG_ON(part->act_state != XPC_P_INACTIVE);
 579
 580         part->act_state = XPC_P_ACTIVATION_REQ;
 581         XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
 582
 583         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 584
 585         pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
 586
 587         if (unlikely(pid <= 0)) {
 588                 spin_lock_irqsave(&part->act_lock, irq_flags);
 589                 part->act_state = XPC_P_INACTIVE;
 590                 XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
 591                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 592         }
 593 }
 594
 595
 596 /*
 597  * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
 598  * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
 599  * than one partition, we use an AMO_t structure per partition to indicate
 600  * whether a partition has sent an IPI or not.  >>> If it has, then wake up the
 601  * associated kthread to handle it.
 602  *
 603  * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
 604  * running on other partitions.
 605  *
 606  * Noteworthy Arguments:
 607  *
 608  *      irq - Interrupt ReQuest number. NOT USED.
 609  *
 610  *      dev_id - partid of IPI's potential sender.
 611  *
 612  *      regs - processor's context before the processor entered
 613  *             interrupt code. NOT USED.
 614  */
 615 irqreturn_t
 616 xpc_notify_IRQ_handler(int irq, void *dev_id, struct pt_regs *regs)
 617 {
 618         partid_t partid = (partid_t) (u64) dev_id;
 619         struct xpc_partition *part = &xpc_partitions[partid];
 620
 621
 622         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 623
 624         if (xpc_part_ref(part)) {
 625                 xpc_check_for_channel_activity(part);
 626
 627                 xpc_part_deref(part);
 628         }
 629         return IRQ_HANDLED;
 630 }
 631
 632
 633 /*
 634  * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
 635  * because the write to their associated IPI amo completed after the IRQ/IPI
 636  * was received.
 637  */
 638 void
 639 xpc_dropped_IPI_check(struct xpc_partition *part)
 640 {
 641         if (xpc_part_ref(part)) {
 642                 xpc_check_for_channel_activity(part);
 643
 644                 part->dropped_IPI_timer.expires = jiffies +
 645                                                         XPC_P_DROPPED_IPI_WAIT;
 646                 add_timer(&part->dropped_IPI_timer);
 647                 xpc_part_deref(part);
 648         }
 649 }
 650
 651
 652 void
 653 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
 654 {
 655         int idle = atomic_read(&ch->kthreads_idle);
 656         int assigned = atomic_read(&ch->kthreads_assigned);
 657         int wakeup;
 658
 659
 660         DBUG_ON(needed <= 0);
 661
 662         if (idle > 0) {
 663                 wakeup = (needed > idle) ? idle : needed;
 664                 needed -= wakeup;
 665
 666                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
 667                         "channel=%d\n", wakeup, ch->partid, ch->number);
 668
 669                 /* only wakeup the requested number of kthreads */
 670                 wake_up_nr(&ch->idle_wq, wakeup);
 671         }
 672
 673         if (needed <= 0) {
 674                 return;
 675         }
 676
 677         if (needed + assigned > ch->kthreads_assigned_limit) {
 678                 needed = ch->kthreads_assigned_limit - assigned;
 679                 // >>>should never be less than 0
 680                 if (needed <= 0) {
 681                         return;
 682                 }
 683         }
 684
 685         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
 686                 needed, ch->partid, ch->number);
 687
 688         xpc_create_kthreads(ch, needed);
 689 }
 690
 691
 692 /*
 693  * This function is where XPC's kthreads wait for messages to deliver.
 694  */
 695 static void
 696 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
 697 {
 698         do {
 699                 /* deliver messages to their intended recipients */
 700
 701                 while ((volatile s64) ch->w_local_GP.get <
 702                                 (volatile s64) ch->w_remote_GP.put &&
 703                                         !((volatile u32) ch->flags &
 704                                                 XPC_C_DISCONNECTING)) {
 705                         xpc_deliver_msg(ch);
 706                 }
 707
 708                 if (atomic_inc_return(&ch->kthreads_idle) >
 709                                                 ch->kthreads_idle_limit) {
 710                         /* too many idle kthreads on this channel */
 711                         atomic_dec(&ch->kthreads_idle);
 712                         break;
 713                 }
 714
 715                 dev_dbg(xpc_chan, "idle kthread calling "
 716                         "wait_event_interruptible_exclusive()\n");
 717
 718                 (void) wait_event_interruptible_exclusive(ch->idle_wq,
 719                                 ((volatile s64) ch->w_local_GP.get <
 720                                         (volatile s64) ch->w_remote_GP.put ||
 721                                 ((volatile u32) ch->flags &
 722                                                 XPC_C_DISCONNECTING)));
 723
 724                 atomic_dec(&ch->kthreads_idle);
 725
 726         } while (!((volatile u32) ch->flags & XPC_C_DISCONNECTING));
 727 }
 728
 729
 730 static int
 731 xpc_daemonize_kthread(void *args)
 732 {
 733         partid_t partid = XPC_UNPACK_ARG1(args);
 734         u16 ch_number = XPC_UNPACK_ARG2(args);
 735         struct xpc_partition *part = &xpc_partitions[partid];
 736         struct xpc_channel *ch;
 737         int n_needed;
 738         unsigned long irq_flags;
 739
 740
 741         daemonize("xpc%02dc%d", partid, ch_number);
 742
 743         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
 744                 partid, ch_number);
 745
 746         ch = &part->channels[ch_number];
 747
 748         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 749
 750                 /* let registerer know that connection has been established */
 751
 752                 spin_lock_irqsave(&ch->lock, irq_flags);
 753                 if (!(ch->flags & XPC_C_CONNECTCALLOUT)) {
 754                         ch->flags |= XPC_C_CONNECTCALLOUT;
 755                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 756
 757                         xpc_connected_callout(ch);
 758
 759                         /*
 760                          * It is possible that while the callout was being
 761                          * made that the remote partition sent some messages.
 762                          * If that is the case, we may need to activate
 763                          * additional kthreads to help deliver them. We only
 764                          * need one less than total #of messages to deliver.
 765                          */
 766                         n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
 767                         if (n_needed > 0 &&
 768                                         !(ch->flags & XPC_C_DISCONNECTING)) {
 769                                 xpc_activate_kthreads(ch, n_needed);
 770                         }
 771                 } else {
 772                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 773                 }
 774
 775                 xpc_kthread_waitmsgs(part, ch);
 776         }
 777
 778         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
 779                 spin_lock_irqsave(&ch->lock, irq_flags);
 780                 if ((ch->flags & XPC_C_CONNECTCALLOUT) &&
 781                                 !(ch->flags & XPC_C_DISCONNECTCALLOUT)) {
 782                         ch->flags |= XPC_C_DISCONNECTCALLOUT;
 783                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 784
 785                         xpc_disconnect_callout(ch, xpcDisconnecting);
 786                 } else {
 787                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 788                 }
 789                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
 790                         xpc_mark_partition_disengaged(part);
 791                         xpc_IPI_send_disengage(part);
 792                 }
 793         }
 794
 795
 796         xpc_msgqueue_deref(ch);
 797
 798         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 799                 partid, ch_number);
 800
 801         xpc_part_deref(part);
 802         return 0;
 803 }
 804
 805
 806 /*
 807  * For each partition that XPC has established communications with, there is
 808  * a minimum of one kernel thread assigned to perform any operation that
 809  * may potentially sleep or block (basically the callouts to the asynchronous
 810  * functions registered via xpc_connect()).
 811  *
 812  * Additional kthreads are created and destroyed by XPC as the workload
 813  * demands.
 814  *
 815  * A kthread is assigned to one of the active channels that exists for a given
 816  * partition.
 817  */
 818 void
 819 xpc_create_kthreads(struct xpc_channel *ch, int needed)
 820 {
 821         unsigned long irq_flags;
 822         pid_t pid;
 823         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
 824         struct xpc_partition *part = &xpc_partitions[ch->partid];
 825
 826
 827         while (needed-- > 0) {
 828
 829                 /*
 830                  * The following is done on behalf of the newly created
 831                  * kthread. That kthread is responsible for doing the
 832                  * counterpart to the following before it exits.
 833                  */
 834                 (void) xpc_part_ref(part);
 835                 xpc_msgqueue_ref(ch);
 836                 if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
 837                     atomic_inc_return(&part->nchannels_engaged) == 1) {
 838                         xpc_mark_partition_engaged(part);
 839                 }
 840
 841                 pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
 842                 if (pid < 0) {
 843                         /* the fork failed */
 844                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 845                             atomic_dec_return(&part->nchannels_engaged) == 0) {
 846                                 xpc_mark_partition_disengaged(part);
 847                                 xpc_IPI_send_disengage(part);
 848                         }
 849                         xpc_msgqueue_deref(ch);
 850                         xpc_part_deref(part);
 851
 852                         if (atomic_read(&ch->kthreads_assigned) <
 853                                                 ch->kthreads_idle_limit) {
 854                                 /*
 855                                  * Flag this as an error only if we have an
 856                                  * insufficient #of kthreads for the channel
 857                                  * to function.
 858                                  *
 859                                  * No xpc_msgqueue_ref() is needed here since
 860                                  * the channel mgr is doing this.
 861                                  */
 862                                 spin_lock_irqsave(&ch->lock, irq_flags);
 863                                 XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
 864                                                                 &irq_flags);
 865                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 866                         }
 867                         break;
 868                 }
 869
 870                 ch->kthreads_created++; // >>> temporary debug only!!!
 871         }
 872 }
 873
 874
 875 void
 876 xpc_disconnect_wait(int ch_number)
 877 {
 878         unsigned long irq_flags;
 879         partid_t partid;
 880         struct xpc_partition *part;
 881         struct xpc_channel *ch;
 882         int wakeup_channel_mgr;
 883
 884
 885         /* now wait for all callouts to the caller's function to cease */
 886         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 887                 part = &xpc_partitions[partid];
 888
 889                 if (!xpc_part_ref(part)) {
 890                         continue;
 891                 }
 892
 893                 ch = &part->channels[ch_number];
 894
 895                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
 896                         xpc_part_deref(part);
 897                         continue;
 898                 }
 899
 900                 wait_for_completion(&ch->wdisconnect_wait);
 901
 902                 spin_lock_irqsave(&ch->lock, irq_flags);
 903                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 904                 wakeup_channel_mgr = 0;
 905
 906                 if (ch->delayed_IPI_flags) {
 907                         if (part->act_state != XPC_P_DEACTIVATING) {
 908                                 spin_lock(&part->IPI_lock);
 909                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 910                                         ch->number, ch->delayed_IPI_flags);
 911                                 spin_unlock(&part->IPI_lock);
 912                                 wakeup_channel_mgr = 1;
 913                         }
 914                         ch->delayed_IPI_flags = 0;
 915                 }
 916
 917                 ch->flags &= ~XPC_C_WDISCONNECT;
 918                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 919
 920                 if (wakeup_channel_mgr) {
 921                         xpc_wakeup_channel_mgr(part);
 922                 }
 923
 924                 xpc_part_deref(part);
 925         }
 926 }
 927
 928
 929 static void
 930 xpc_do_exit(enum xpc_retval reason)
 931 {
 932         partid_t partid;
 933         int active_part_count, printed_waiting_msg = 0;
 934         struct xpc_partition *part;
 935         unsigned long printmsg_time, disengage_request_timeout = 0;
 936
 937
 938         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 939         DBUG_ON(xpc_exiting == 1);
 940
 941         /*
 942          * Let the heartbeat checker thread and the discovery thread
 943          * (if one is running) know that they should exit. Also wake up
 944          * the heartbeat checker thread in case it's sleeping.
 945          */
 946         xpc_exiting = 1;
 947         wake_up_interruptible(&xpc_act_IRQ_wq);
 948
 949         /* ignore all incoming interrupts */
 950         free_irq(SGI_XPC_ACTIVATE, NULL);
 951
 952         /* wait for the discovery thread to exit */
 953         wait_for_completion(&xpc_discovery_exited);
 954
 955         /* wait for the heartbeat checker thread to exit */
 956         wait_for_completion(&xpc_hb_checker_exited);
 957
 958
 959         /* sleep for a 1/3 of a second or so */
 960         (void) msleep_interruptible(300);
 961
 962
 963         /* wait for all partitions to become inactive */
 964
 965         printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 966         xpc_disengage_request_timedout = 0;
 967
 968         do {
 969                 active_part_count = 0;
 970
 971                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 972                         part = &xpc_partitions[partid];
 973
 974                         if (xpc_partition_disengaged(part) &&
 975                                         part->act_state == XPC_P_INACTIVE) {
 976                                 continue;
 977                         }
 978
 979                         active_part_count++;
 980
 981                         XPC_DEACTIVATE_PARTITION(part, reason);
 982
 983                         if (part->disengage_request_timeout >
 984                                                 disengage_request_timeout) {
 985                                 disengage_request_timeout =
 986                                                 part->disengage_request_timeout;
 987                         }
 988                 }
 989
 990                 if (xpc_partition_engaged(-1UL)) {
 991                         if (time_after(jiffies, printmsg_time)) {
 992                                 dev_info(xpc_part, "waiting for remote "
 993                                         "partitions to disengage, timeout in "
 994                                         "%ld seconds\n",
 995                                         (disengage_request_timeout - jiffies)
 996                                                                         / HZ);
 997                                 printmsg_time = jiffies +
 998                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 999                                 printed_waiting_msg = 1;
1000                         }
1001
1002                 } else if (active_part_count > 0) {
1003                         if (printed_waiting_msg) {
1004                                 dev_info(xpc_part, "waiting for local partition"
1005                                         " to disengage\n");
1006                                 printed_waiting_msg = 0;
1007                         }
1008
1009                 } else {
1010                         if (!xpc_disengage_request_timedout) {
1011                                 dev_info(xpc_part, "all partitions have "
1012                                         "disengaged\n");
1013                         }
1014                         break;
1015                 }
1016
1017                 /* sleep for a 1/3 of a second or so */
1018                 (void) msleep_interruptible(300);
1019
1020         } while (1);
1021
1022         DBUG_ON(xpc_partition_engaged(-1UL));
1023
1024
1025         /* indicate to others that our reserved page is uninitialized */
1026         xpc_rsvd_page->vars_pa = 0;
1027
1028         /* now it's time to eliminate our heartbeat */
1029         del_timer_sync(&xpc_hb_timer);
1030         DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
1031
1032         if (reason == xpcUnloading) {
1033                 /* take ourselves off of the reboot_notifier_list */
1034                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1035
1036                 /* take ourselves off of the die_notifier list */
1037                 (void) unregister_die_notifier(&xpc_die_notifier);
1038         }
1039
1040         /* close down protections for IPI operations */
1041         xpc_restrict_IPI_ops();
1042
1043
1044         /* clear the interface to XPC's functions */
1045         xpc_clear_interface();
1046
1047         if (xpc_sysctl) {
1048                 unregister_sysctl_table(xpc_sysctl);
1049         }
1050 }
1051
1052
1053 /*
1054  * This function is called when the system is being rebooted.
1055  */
1056 static int
1057 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1058 {
1059         enum xpc_retval reason;
1060
1061
1062         switch (event) {
1063         case SYS_RESTART:
1064                 reason = xpcSystemReboot;
1065                 break;
1066         case SYS_HALT:
1067                 reason = xpcSystemHalt;
1068                 break;
1069         case SYS_POWER_OFF:
1070                 reason = xpcSystemPoweroff;
1071                 break;
1072         default:
1073                 reason = xpcSystemGoingDown;
1074         }
1075
1076         xpc_do_exit(reason);
1077         return NOTIFY_DONE;
1078 }
1079
1080
1081 /*
1082  * Notify other partitions to disengage from all references to our memory.
1083  */
1084 static void
1085 xpc_die_disengage(void)
1086 {
1087         struct xpc_partition *part;
1088         partid_t partid;
1089         unsigned long engaged;
1090         long time, printmsg_time, disengage_request_timeout;
1091
1092
1093         /* keep xpc_hb_checker thread from doing anything (just in case) */
1094         xpc_exiting = 1;
1095
1096         xpc_vars->heartbeating_to_mask = 0;  /* indicate we're deactivated */
1097
1098         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1099                 part = &xpc_partitions[partid];
1100
1101                 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
1102                                                         remote_vars_version)) {
1103
1104                         /* just in case it was left set by an earlier XPC */
1105                         xpc_clear_partition_engaged(1UL << partid);
1106                         continue;
1107                 }
1108
1109                 if (xpc_partition_engaged(1UL << partid) ||
1110                                         part->act_state != XPC_P_INACTIVE) {
1111                         xpc_request_partition_disengage(part);
1112                         xpc_mark_partition_disengaged(part);
1113                         xpc_IPI_send_disengage(part);
1114                 }
1115         }
1116
1117         time = rtc_time();
1118         printmsg_time = time +
1119                 (XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
1120         disengage_request_timeout = time +
1121                 (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1122
1123         /* wait for all other partitions to disengage from us */
1124
1125         while (1) {
1126                 engaged = xpc_partition_engaged(-1UL);
1127                 if (!engaged) {
1128                         dev_info(xpc_part, "all partitions have disengaged\n");
1129                         break;
1130                 }
1131
1132                 time = rtc_time();
1133                 if (time >= disengage_request_timeout) {
1134                         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1135                                 if (engaged & (1UL << partid)) {
1136                                         dev_info(xpc_part, "disengage from "
1137                                                 "remote partition %d timed "
1138                                                 "out\n", partid);
1139                                 }
1140                         }
1141                         break;
1142                 }
1143
1144                 if (time >= printmsg_time) {
1145                         dev_info(xpc_part, "waiting for remote partitions to "
1146                                 "disengage, timeout in %ld seconds\n",
1147                                 (disengage_request_timeout - time) /
1148                                                 sn_rtc_cycles_per_second);
1149                         printmsg_time = time +
1150                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1151                                                 sn_rtc_cycles_per_second);
1152                 }
1153         }
1154 }
1155
1156
1157 /*
1158  * This function is called when the system is being restarted or halted due
1159  * to some sort of system failure. If this is the case we need to notify the
1160  * other partitions to disengage from all references to our memory.
1161  * This function can also be called when our heartbeater could be offlined
1162  * for a time. In this case we need to notify other partitions to not worry
1163  * about the lack of a heartbeat.
1164  */
1165 static int
1166 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1167 {
1168         switch (event) {
1169         case DIE_MACHINE_RESTART:
1170         case DIE_MACHINE_HALT:
1171                 xpc_die_disengage();
1172                 break;
1173
1174         case DIE_KDEBUG_ENTER:
1175                 /* Should lack of heartbeat be ignored by other partitions? */
1176                 if (!xpc_kdebug_ignore) {
1177                         break;
1178                 }
1179                 /* fall through */
1180         case DIE_MCA_MONARCH_ENTER:
1181         case DIE_INIT_MONARCH_ENTER:
1182                 xpc_vars->heartbeat++;
1183                 xpc_vars->heartbeat_offline = 1;
1184                 break;
1185
1186         case DIE_KDEBUG_LEAVE:
1187                 /* Is lack of heartbeat being ignored by other partitions? */
1188                 if (!xpc_kdebug_ignore) {
1189                         break;
1190                 }
1191                 /* fall through */
1192         case DIE_MCA_MONARCH_LEAVE:
1193         case DIE_INIT_MONARCH_LEAVE:
1194                 xpc_vars->heartbeat++;
1195                 xpc_vars->heartbeat_offline = 0;
1196                 break;
1197         }
1198
1199         return NOTIFY_DONE;
1200 }
1201
1202
1203 int __init
1204 xpc_init(void)
1205 {
1206         int ret;
1207         partid_t partid;
1208         struct xpc_partition *part;
1209         pid_t pid;
1210
1211
1212         if (!ia64_platform_is("sn2")) {
1213                 return -ENODEV;
1214         }
1215
1216         /*
1217          * xpc_remote_copy_buffer is used as a temporary buffer for bte_copy'ng
1218          * various portions of a partition's reserved page. Its size is based
1219          * on the size of the reserved page header and part_nasids mask. So we
1220          * need to ensure that the other items will fit as well.
1221          */
1222         if (XPC_RP_VARS_SIZE > XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES) {
1223                 dev_err(xpc_part, "xpc_remote_copy_buffer is not big enough\n");
1224                 return -EPERM;
1225         }
1226         DBUG_ON((u64) xpc_remote_copy_buffer !=
1227                                 L1_CACHE_ALIGN((u64) xpc_remote_copy_buffer));
1228
1229         snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1230         snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1231
1232         xpc_sysctl = register_sysctl_table(xpc_sys_dir, 1);
1233
1234         /*
1235          * The first few fields of each entry of xpc_partitions[] need to
1236          * be initialized now so that calls to xpc_connect() and
1237          * xpc_disconnect() can be made prior to the activation of any remote
1238          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1239          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1240          * PARTITION HAS BEEN ACTIVATED.
1241          */
1242         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1243                 part = &xpc_partitions[partid];
1244
1245                 DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
1246
1247                 part->act_IRQ_rcvd = 0;
1248                 spin_lock_init(&part->act_lock);
1249                 part->act_state = XPC_P_INACTIVE;
1250                 XPC_SET_REASON(part, 0, 0);
1251
1252                 init_timer(&part->disengage_request_timer);
1253                 part->disengage_request_timer.function =
1254                                 xpc_timeout_partition_disengage_request;
1255                 part->disengage_request_timer.data = (unsigned long) part;
1256
1257                 part->setup_state = XPC_P_UNSET;
1258                 init_waitqueue_head(&part->teardown_wq);
1259                 atomic_set(&part->references, 0);
1260         }
1261
1262         /*
1263          * Open up protections for IPI operations (and AMO operations on
1264          * Shub 1.1 systems).
1265          */
1266         xpc_allow_IPI_ops();
1267
1268         /*
1269          * Interrupts being processed will increment this atomic variable and
1270          * awaken the heartbeat thread which will process the interrupts.
1271          */
1272         atomic_set(&xpc_act_IRQ_rcvd, 0);
1273
1274         /*
1275          * This is safe to do before the xpc_hb_checker thread has started
1276          * because the handler releases a wait queue.  If an interrupt is
1277          * received before the thread is waiting, it will not go to sleep,
1278          * but rather immediately process the interrupt.
1279          */
1280         ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1281                                                         "xpc hb", NULL);
1282         if (ret != 0) {
1283                 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1284                         "errno=%d\n", -ret);
1285
1286                 xpc_restrict_IPI_ops();
1287
1288                 if (xpc_sysctl) {
1289                         unregister_sysctl_table(xpc_sysctl);
1290                 }
1291                 return -EBUSY;
1292         }
1293
1294         /*
1295          * Fill the partition reserved page with the information needed by
1296          * other partitions to discover we are alive and establish initial
1297          * communications.
1298          */
1299         xpc_rsvd_page = xpc_rsvd_page_init();
1300         if (xpc_rsvd_page == NULL) {
1301                 dev_err(xpc_part, "could not setup our reserved page\n");
1302
1303                 free_irq(SGI_XPC_ACTIVATE, NULL);
1304                 xpc_restrict_IPI_ops();
1305
1306                 if (xpc_sysctl) {
1307                         unregister_sysctl_table(xpc_sysctl);
1308                 }
1309                 return -EBUSY;
1310         }
1311
1312
1313         /* add ourselves to the reboot_notifier_list */
1314         ret = register_reboot_notifier(&xpc_reboot_notifier);
1315         if (ret != 0) {
1316                 dev_warn(xpc_part, "can't register reboot notifier\n");
1317         }
1318
1319         /* add ourselves to the die_notifier list (i.e., ia64die_chain) */
1320         ret = register_die_notifier(&xpc_die_notifier);
1321         if (ret != 0) {
1322                 dev_warn(xpc_part, "can't register die notifier\n");
1323         }
1324
1325
1326         /*
1327          * Set the beating to other partitions into motion.  This is
1328          * the last requirement for other partitions' discovery to
1329          * initiate communications with us.
1330          */
1331         init_timer(&xpc_hb_timer);
1332         xpc_hb_timer.function = xpc_hb_beater;
1333         xpc_hb_beater(0);
1334
1335
1336         /*
1337          * The real work-horse behind xpc.  This processes incoming
1338          * interrupts and monitors remote heartbeats.
1339          */
1340         pid = kernel_thread(xpc_hb_checker, NULL, 0);
1341         if (pid < 0) {
1342                 dev_err(xpc_part, "failed while forking hb check thread\n");
1343
1344                 /* indicate to others that our reserved page is uninitialized */
1345                 xpc_rsvd_page->vars_pa = 0;
1346
1347                 /* take ourselves off of the reboot_notifier_list */
1348                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1349
1350                 /* take ourselves off of the die_notifier list */
1351                 (void) unregister_die_notifier(&xpc_die_notifier);
1352
1353                 del_timer_sync(&xpc_hb_timer);
1354                 free_irq(SGI_XPC_ACTIVATE, NULL);
1355                 xpc_restrict_IPI_ops();
1356
1357                 if (xpc_sysctl) {
1358                         unregister_sysctl_table(xpc_sysctl);
1359                 }
1360                 return -EBUSY;
1361         }
1362
1363
1364         /*
1365          * Startup a thread that will attempt to discover other partitions to
1366          * activate based on info provided by SAL. This new thread is short
1367          * lived and will exit once discovery is complete.
1368          */
1369         pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
1370         if (pid < 0) {
1371                 dev_err(xpc_part, "failed while forking discovery thread\n");
1372
1373                 /* mark this new thread as a non-starter */
1374                 complete(&xpc_discovery_exited);
1375
1376                 xpc_do_exit(xpcUnloading);
1377                 return -EBUSY;
1378         }
1379
1380
1381         /* set the interface to point at XPC's functions */
1382         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1383                           xpc_initiate_allocate, xpc_initiate_send,
1384                           xpc_initiate_send_notify, xpc_initiate_received,
1385                           xpc_initiate_partid_to_nasids);
1386
1387         return 0;
1388 }
1389 module_init(xpc_init);
1390
1391
1392 void __exit
1393 xpc_exit(void)
1394 {
1395         xpc_do_exit(xpcUnloading);
1396 }
1397 module_exit(xpc_exit);
1398
1399
1400 MODULE_AUTHOR("Silicon Graphics, Inc.");
1401 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1402 MODULE_LICENSE("GPL");
1403
1404 module_param(xpc_hb_interval, int, 0);
1405 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1406                 "heartbeat increments.");
1407
1408 module_param(xpc_hb_check_interval, int, 0);
1409 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1410                 "heartbeat checks.");
1411
1412 module_param(xpc_disengage_request_timelimit, int, 0);
1413 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1414                 "for disengage request to complete.");
1415
1416 module_param(xpc_kdebug_ignore, int, 0);
1417 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1418                 "other partitions when dropping into kdebug.");
1419