arch/ia64/sn/kernel/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) 2004-2006 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/delay.h>
  56 #include <linux/reboot.h>
  57 #include <linux/completion.h>
  58 #include <asm/sn/intr.h>
  59 #include <asm/sn/sn_sal.h>
  60 #include <asm/kdebug.h>
  61 #include <asm/uaccess.h>
  62 #include <asm/sn/xpc.h>
  63
  64
  65 /* define two XPC debug device structures to be used with dev_dbg() et al */
  66
  67 struct device_driver xpc_dbg_name = {
  68         .name = "xpc"
  69 };
  70
  71 struct device xpc_part_dbg_subname = {
  72         .bus_id = {0},          /* set to "part" at xpc_init() time */
  73         .driver = &xpc_dbg_name
  74 };
  75
  76 struct device xpc_chan_dbg_subname = {
  77         .bus_id = {0},          /* set to "chan" at xpc_init() time */
  78         .driver = &xpc_dbg_name
  79 };
  80
  81 struct device *xpc_part = &xpc_part_dbg_subname;
  82 struct device *xpc_chan = &xpc_chan_dbg_subname;
  83
  84
  85 static int xpc_kdebug_ignore;
  86
  87
  88 /* systune related variables for /proc/sys directories */
  89
  90 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
  91 static int xpc_hb_min_interval = 1;
  92 static int xpc_hb_max_interval = 10;
  93
  94 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
  95 static int xpc_hb_check_min_interval = 10;
  96 static int xpc_hb_check_max_interval = 120;
  97
  98 int xpc_disengage_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
  99 static int xpc_disengage_request_min_timelimit = 0;
 100 static int xpc_disengage_request_max_timelimit = 120;
 101
 102 static ctl_table xpc_sys_xpc_hb_dir[] = {
 103         {
 104                 1,
 105                 "hb_interval",
 106                 &xpc_hb_interval,
 107                 sizeof(int),
 108                 0644,
 109                 NULL,
 110                 &proc_dointvec_minmax,
 111                 &sysctl_intvec,
 112                 NULL,
 113                 &xpc_hb_min_interval,
 114                 &xpc_hb_max_interval
 115         },
 116         {
 117                 2,
 118                 "hb_check_interval",
 119                 &xpc_hb_check_interval,
 120                 sizeof(int),
 121                 0644,
 122                 NULL,
 123                 &proc_dointvec_minmax,
 124                 &sysctl_intvec,
 125                 NULL,
 126                 &xpc_hb_check_min_interval,
 127                 &xpc_hb_check_max_interval
 128         },
 129         {0}
 130 };
 131 static ctl_table xpc_sys_xpc_dir[] = {
 132         {
 133                 1,
 134                 "hb",
 135                 NULL,
 136                 0,
 137                 0555,
 138                 xpc_sys_xpc_hb_dir
 139         },
 140         {
 141                 2,
 142                 "disengage_request_timelimit",
 143                 &xpc_disengage_request_timelimit,
 144                 sizeof(int),
 145                 0644,
 146                 NULL,
 147                 &proc_dointvec_minmax,
 148                 &sysctl_intvec,
 149                 NULL,
 150                 &xpc_disengage_request_min_timelimit,
 151                 &xpc_disengage_request_max_timelimit
 152         },
 153         {0}
 154 };
 155 static ctl_table xpc_sys_dir[] = {
 156         {
 157                 1,
 158                 "xpc",
 159                 NULL,
 160                 0,
 161                 0555,
 162                 xpc_sys_xpc_dir
 163         },
 164         {0}
 165 };
 166 static struct ctl_table_header *xpc_sysctl;
 167
 168 /* non-zero if any remote partition disengage request was timed out */
 169 int xpc_disengage_request_timedout;
 170
 171 /* #of IRQs received */
 172 static atomic_t xpc_act_IRQ_rcvd;
 173
 174 /* IRQ handler notifies this wait queue on receipt of an IRQ */
 175 static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
 176
 177 static unsigned long xpc_hb_check_timeout;
 178
 179 /* notification that the xpc_hb_checker thread has exited */
 180 static DECLARE_COMPLETION(xpc_hb_checker_exited);
 181
 182 /* notification that the xpc_discovery thread has exited */
 183 static DECLARE_COMPLETION(xpc_discovery_exited);
 184
 185
 186 static struct timer_list xpc_hb_timer;
 187
 188
 189 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
 190
 191
 192 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
 193 static struct notifier_block xpc_reboot_notifier = {
 194         .notifier_call = xpc_system_reboot,
 195 };
 196
 197 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
 198 static struct notifier_block xpc_die_notifier = {
 199         .notifier_call = xpc_system_die,
 200 };
 201
 202
 203 /*
 204  * Timer function to enforce the timelimit on the partition disengage request.
 205  */
 206 static void
 207 xpc_timeout_partition_disengage_request(unsigned long data)
 208 {
 209         struct xpc_partition *part = (struct xpc_partition *) data;
 210
 211
 212         DBUG_ON(jiffies < part->disengage_request_timeout);
 213
 214         (void) xpc_partition_disengaged(part);
 215
 216         DBUG_ON(part->disengage_request_timeout != 0);
 217         DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
 218 }
 219
 220
 221 /*
 222  * Notify the heartbeat check thread that an IRQ has been received.
 223  */
 224 static irqreturn_t
 225 xpc_act_IRQ_handler(int irq, void *dev_id)
 226 {
 227         atomic_inc(&xpc_act_IRQ_rcvd);
 228         wake_up_interruptible(&xpc_act_IRQ_wq);
 229         return IRQ_HANDLED;
 230 }
 231
 232
 233 /*
 234  * Timer to produce the heartbeat.  The timer structures function is
 235  * already set when this is initially called.  A tunable is used to
 236  * specify when the next timeout should occur.
 237  */
 238 static void
 239 xpc_hb_beater(unsigned long dummy)
 240 {
 241         xpc_vars->heartbeat++;
 242
 243         if (jiffies >= xpc_hb_check_timeout) {
 244                 wake_up_interruptible(&xpc_act_IRQ_wq);
 245         }
 246
 247         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
 248         add_timer(&xpc_hb_timer);
 249 }
 250
 251
 252 /*
 253  * This thread is responsible for nearly all of the partition
 254  * activation/deactivation.
 255  */
 256 static int
 257 xpc_hb_checker(void *ignore)
 258 {
 259         int last_IRQ_count = 0;
 260         int new_IRQ_count;
 261         int force_IRQ=0;
 262
 263
 264         /* this thread was marked active by xpc_hb_init() */
 265
 266         daemonize(XPC_HB_CHECK_THREAD_NAME);
 267
 268         set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
 269
 270         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
 271
 272         while (!(volatile int) xpc_exiting) {
 273
 274                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
 275                         "been received\n",
 276                         (int) (xpc_hb_check_timeout - jiffies),
 277                         atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
 278
 279
 280                 /* checking of remote heartbeats is skewed by IRQ handling */
 281                 if (jiffies >= xpc_hb_check_timeout) {
 282                         dev_dbg(xpc_part, "checking remote heartbeats\n");
 283                         xpc_check_remote_hb();
 284
 285                         /*
 286                          * We need to periodically recheck to ensure no
 287                          * IPI/AMO pairs have been missed.  That check
 288                          * must always reset xpc_hb_check_timeout.
 289                          */
 290                         force_IRQ = 1;
 291                 }
 292
 293
 294                 /* check for outstanding IRQs */
 295                 new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
 296                 if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
 297                         force_IRQ = 0;
 298
 299                         dev_dbg(xpc_part, "found an IRQ to process; will be "
 300                                 "resetting xpc_hb_check_timeout\n");
 301
 302                         last_IRQ_count += xpc_identify_act_IRQ_sender();
 303                         if (last_IRQ_count < new_IRQ_count) {
 304                                 /* retry once to help avoid missing AMO */
 305                                 (void) xpc_identify_act_IRQ_sender();
 306                         }
 307                         last_IRQ_count = new_IRQ_count;
 308
 309                         xpc_hb_check_timeout = jiffies +
 310                                            (xpc_hb_check_interval * HZ);
 311                 }
 312
 313                 /* wait for IRQ or timeout */
 314                 (void) wait_event_interruptible(xpc_act_IRQ_wq,
 315                             (last_IRQ_count < atomic_read(&xpc_act_IRQ_rcvd) ||
 316                                         jiffies >= xpc_hb_check_timeout ||
 317                                                 (volatile int) xpc_exiting));
 318         }
 319
 320         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 321
 322
 323         /* mark this thread as having exited */
 324         complete(&xpc_hb_checker_exited);
 325         return 0;
 326 }
 327
 328
 329 /*
 330  * This thread will attempt to discover other partitions to activate
 331  * based on info provided by SAL. This new thread is short lived and
 332  * will exit once discovery is complete.
 333  */
 334 static int
 335 xpc_initiate_discovery(void *ignore)
 336 {
 337         daemonize(XPC_DISCOVERY_THREAD_NAME);
 338
 339         xpc_discovery();
 340
 341         dev_dbg(xpc_part, "discovery thread is exiting\n");
 342
 343         /* mark this thread as having exited */
 344         complete(&xpc_discovery_exited);
 345         return 0;
 346 }
 347
 348
 349 /*
 350  * Establish first contact with the remote partititon. This involves pulling
 351  * the XPC per partition variables from the remote partition and waiting for
 352  * the remote partition to pull ours.
 353  */
 354 static enum xpc_retval
 355 xpc_make_first_contact(struct xpc_partition *part)
 356 {
 357         enum xpc_retval ret;
 358
 359
 360         while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
 361                 if (ret != xpcRetry) {
 362                         XPC_DEACTIVATE_PARTITION(part, ret);
 363                         return ret;
 364                 }
 365
 366                 dev_dbg(xpc_chan, "waiting to make first contact with "
 367                         "partition %d\n", XPC_PARTID(part));
 368
 369                 /* wait a 1/4 of a second or so */
 370                 (void) msleep_interruptible(250);
 371
 372                 if (part->act_state == XPC_P_DEACTIVATING) {
 373                         return part->reason;
 374                 }
 375         }
 376
 377         return xpc_mark_partition_active(part);
 378 }
 379
 380
 381 /*
 382  * The first kthread assigned to a newly activated partition is the one
 383  * created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
 384  * that kthread until the partition is brought down, at which time that kthread
 385  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
 386  * that XPC has dismantled all communication infrastructure for the associated
 387  * partition.) This kthread becomes the channel manager for that partition.
 388  *
 389  * Each active partition has a channel manager, who, besides connecting and
 390  * disconnecting channels, will ensure that each of the partition's connected
 391  * channels has the required number of assigned kthreads to get the work done.
 392  */
 393 static void
 394 xpc_channel_mgr(struct xpc_partition *part)
 395 {
 396         while (part->act_state != XPC_P_DEACTIVATING ||
 397                         atomic_read(&part->nchannels_active) > 0 ||
 398                                         !xpc_partition_disengaged(part)) {
 399
 400                 xpc_process_channel_activity(part);
 401
 402
 403                 /*
 404                  * Wait until we've been requested to activate kthreads or
 405                  * all of the channel's message queues have been torn down or
 406                  * a signal is pending.
 407                  *
 408                  * The channel_mgr_requests is set to 1 after being awakened,
 409                  * This is done to prevent the channel mgr from making one pass
 410                  * through the loop for each request, since he will
 411                  * be servicing all the requests in one pass. The reason it's
 412                  * set to 1 instead of 0 is so that other kthreads will know
 413                  * that the channel mgr is running and won't bother trying to
 414                  * wake him up.
 415                  */
 416                 atomic_dec(&part->channel_mgr_requests);
 417                 (void) wait_event_interruptible(part->channel_mgr_wq,
 418                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
 419                                 (volatile u64) part->local_IPI_amo != 0 ||
 420                                 ((volatile u8) part->act_state ==
 421                                                         XPC_P_DEACTIVATING &&
 422                                 atomic_read(&part->nchannels_active) == 0 &&
 423                                 xpc_partition_disengaged(part))));
 424                 atomic_set(&part->channel_mgr_requests, 1);
 425
 426                 // >>> Does it need to wakeup periodically as well? In case we
 427                 // >>> miscalculated the #of kthreads to wakeup or create?
 428         }
 429 }
 430
 431
 432 /*
 433  * When XPC HB determines that a partition has come up, it will create a new
 434  * kthread and that kthread will call this function to attempt to set up the
 435  * basic infrastructure used for Cross Partition Communication with the newly
 436  * upped partition.
 437  *
 438  * The kthread that was created by XPC HB and which setup the XPC
 439  * infrastructure will remain assigned to the partition until the partition
 440  * goes down. At which time the kthread will teardown the XPC infrastructure
 441  * and then exit.
 442  *
 443  * XPC HB will put the remote partition's XPC per partition specific variables
 444  * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
 445  * calling xpc_partition_up().
 446  */
 447 static void
 448 xpc_partition_up(struct xpc_partition *part)
 449 {
 450         DBUG_ON(part->channels != NULL);
 451
 452         dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
 453
 454         if (xpc_setup_infrastructure(part) != xpcSuccess) {
 455                 return;
 456         }
 457
 458         /*
 459          * The kthread that XPC HB called us with will become the
 460          * channel manager for this partition. It will not return
 461          * back to XPC HB until the partition's XPC infrastructure
 462          * has been dismantled.
 463          */
 464
 465         (void) xpc_part_ref(part);      /* this will always succeed */
 466
 467         if (xpc_make_first_contact(part) == xpcSuccess) {
 468                 xpc_channel_mgr(part);
 469         }
 470
 471         xpc_part_deref(part);
 472
 473         xpc_teardown_infrastructure(part);
 474 }
 475
 476
 477 static int
 478 xpc_activating(void *__partid)
 479 {
 480         partid_t partid = (u64) __partid;
 481         struct xpc_partition *part = &xpc_partitions[partid];
 482         unsigned long irq_flags;
 483         struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 484         int ret;
 485
 486
 487         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 488
 489         spin_lock_irqsave(&part->act_lock, irq_flags);
 490
 491         if (part->act_state == XPC_P_DEACTIVATING) {
 492                 part->act_state = XPC_P_INACTIVE;
 493                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 494                 part->remote_rp_pa = 0;
 495                 return 0;
 496         }
 497
 498         /* indicate the thread is activating */
 499         DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
 500         part->act_state = XPC_P_ACTIVATING;
 501
 502         XPC_SET_REASON(part, 0, 0);
 503         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 504
 505         dev_dbg(xpc_part, "bringing partition %d up\n", partid);
 506
 507         daemonize("xpc%02d", partid);
 508
 509         /*
 510          * This thread needs to run at a realtime priority to prevent a
 511          * significant performance degradation.
 512          */
 513         ret = sched_setscheduler(current, SCHED_FIFO, &param);
 514         if (ret != 0) {
 515                 dev_warn(xpc_part, "unable to set pid %d to a realtime "
 516                         "priority, ret=%d\n", current->pid, ret);
 517         }
 518
 519         /* allow this thread and its children to run on any CPU */
 520         set_cpus_allowed(current, CPU_MASK_ALL);
 521
 522         /*
 523          * Register the remote partition's AMOs with SAL so it can handle
 524          * and cleanup errors within that address range should the remote
 525          * partition go down. We don't unregister this range because it is
 526          * difficult to tell when outstanding writes to the remote partition
 527          * are finished and thus when it is safe to unregister. This should
 528          * not result in wasted space in the SAL xp_addr_region table because
 529          * we should get the same page for remote_amos_page_pa after module
 530          * reloads and system reboots.
 531          */
 532         if (sn_register_xp_addr_region(part->remote_amos_page_pa,
 533                                                         PAGE_SIZE, 1) < 0) {
 534                 dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
 535                         "xp_addr region\n", partid);
 536
 537                 spin_lock_irqsave(&part->act_lock, irq_flags);
 538                 part->act_state = XPC_P_INACTIVE;
 539                 XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
 540                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 541                 part->remote_rp_pa = 0;
 542                 return 0;
 543         }
 544
 545         xpc_allow_hb(partid, xpc_vars);
 546         xpc_IPI_send_activated(part);
 547
 548
 549         /*
 550          * xpc_partition_up() holds this thread and marks this partition as
 551          * XPC_P_ACTIVE by calling xpc_hb_mark_active().
 552          */
 553         (void) xpc_partition_up(part);
 554
 555         xpc_disallow_hb(partid, xpc_vars);
 556         xpc_mark_partition_inactive(part);
 557
 558         if (part->reason == xpcReactivating) {
 559                 /* interrupting ourselves results in activating partition */
 560                 xpc_IPI_send_reactivate(part);
 561         }
 562
 563         return 0;
 564 }
 565
 566
 567 void
 568 xpc_activate_partition(struct xpc_partition *part)
 569 {
 570         partid_t partid = XPC_PARTID(part);
 571         unsigned long irq_flags;
 572         pid_t pid;
 573
 574
 575         spin_lock_irqsave(&part->act_lock, irq_flags);
 576
 577         DBUG_ON(part->act_state != XPC_P_INACTIVE);
 578
 579         part->act_state = XPC_P_ACTIVATION_REQ;
 580         XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
 581
 582         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 583
 584         pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
 585
 586         if (unlikely(pid <= 0)) {
 587                 spin_lock_irqsave(&part->act_lock, irq_flags);
 588                 part->act_state = XPC_P_INACTIVE;
 589                 XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
 590                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 591         }
 592 }
 593
 594
 595 /*
 596  * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
 597  * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
 598  * than one partition, we use an AMO_t structure per partition to indicate
 599  * whether a partition has sent an IPI or not.  >>> If it has, then wake up the
 600  * associated kthread to handle it.
 601  *
 602  * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
 603  * running on other partitions.
 604  *
 605  * Noteworthy Arguments:
 606  *
 607  *      irq - Interrupt ReQuest number. NOT USED.
 608  *
 609  *      dev_id - partid of IPI's potential sender.
 610  */
 611 irqreturn_t
 612 xpc_notify_IRQ_handler(int irq, void *dev_id)
 613 {
 614         partid_t partid = (partid_t) (u64) dev_id;
 615         struct xpc_partition *part = &xpc_partitions[partid];
 616
 617
 618         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 619
 620         if (xpc_part_ref(part)) {
 621                 xpc_check_for_channel_activity(part);
 622
 623                 xpc_part_deref(part);
 624         }
 625         return IRQ_HANDLED;
 626 }
 627
 628
 629 /*
 630  * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
 631  * because the write to their associated IPI amo completed after the IRQ/IPI
 632  * was received.
 633  */
 634 void
 635 xpc_dropped_IPI_check(struct xpc_partition *part)
 636 {
 637         if (xpc_part_ref(part)) {
 638                 xpc_check_for_channel_activity(part);
 639
 640                 part->dropped_IPI_timer.expires = jiffies +
 641                                                         XPC_P_DROPPED_IPI_WAIT;
 642                 add_timer(&part->dropped_IPI_timer);
 643                 xpc_part_deref(part);
 644         }
 645 }
 646
 647
 648 void
 649 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
 650 {
 651         int idle = atomic_read(&ch->kthreads_idle);
 652         int assigned = atomic_read(&ch->kthreads_assigned);
 653         int wakeup;
 654
 655
 656         DBUG_ON(needed <= 0);
 657
 658         if (idle > 0) {
 659                 wakeup = (needed > idle) ? idle : needed;
 660                 needed -= wakeup;
 661
 662                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
 663                         "channel=%d\n", wakeup, ch->partid, ch->number);
 664
 665                 /* only wakeup the requested number of kthreads */
 666                 wake_up_nr(&ch->idle_wq, wakeup);
 667         }
 668
 669         if (needed <= 0) {
 670                 return;
 671         }
 672
 673         if (needed + assigned > ch->kthreads_assigned_limit) {
 674                 needed = ch->kthreads_assigned_limit - assigned;
 675                 // >>>should never be less than 0
 676                 if (needed <= 0) {
 677                         return;
 678                 }
 679         }
 680
 681         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
 682                 needed, ch->partid, ch->number);
 683
 684         xpc_create_kthreads(ch, needed, 0);
 685 }
 686
 687
 688 /*
 689  * This function is where XPC's kthreads wait for messages to deliver.
 690  */
 691 static void
 692 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
 693 {
 694         do {
 695                 /* deliver messages to their intended recipients */
 696
 697                 while ((volatile s64) ch->w_local_GP.get <
 698                                 (volatile s64) ch->w_remote_GP.put &&
 699                                         !((volatile u32) ch->flags &
 700                                                 XPC_C_DISCONNECTING)) {
 701                         xpc_deliver_msg(ch);
 702                 }
 703
 704                 if (atomic_inc_return(&ch->kthreads_idle) >
 705                                                 ch->kthreads_idle_limit) {
 706                         /* too many idle kthreads on this channel */
 707                         atomic_dec(&ch->kthreads_idle);
 708                         break;
 709                 }
 710
 711                 dev_dbg(xpc_chan, "idle kthread calling "
 712                         "wait_event_interruptible_exclusive()\n");
 713
 714                 (void) wait_event_interruptible_exclusive(ch->idle_wq,
 715                                 ((volatile s64) ch->w_local_GP.get <
 716                                         (volatile s64) ch->w_remote_GP.put ||
 717                                 ((volatile u32) ch->flags &
 718                                                 XPC_C_DISCONNECTING)));
 719
 720                 atomic_dec(&ch->kthreads_idle);
 721
 722         } while (!((volatile u32) ch->flags & XPC_C_DISCONNECTING));
 723 }
 724
 725
 726 static int
 727 xpc_daemonize_kthread(void *args)
 728 {
 729         partid_t partid = XPC_UNPACK_ARG1(args);
 730         u16 ch_number = XPC_UNPACK_ARG2(args);
 731         struct xpc_partition *part = &xpc_partitions[partid];
 732         struct xpc_channel *ch;
 733         int n_needed;
 734         unsigned long irq_flags;
 735
 736
 737         daemonize("xpc%02dc%d", partid, ch_number);
 738
 739         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
 740                 partid, ch_number);
 741
 742         ch = &part->channels[ch_number];
 743
 744         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 745
 746                 /* let registerer know that connection has been established */
 747
 748                 spin_lock_irqsave(&ch->lock, irq_flags);
 749                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
 750                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
 751                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 752
 753                         xpc_connected_callout(ch);
 754
 755                         spin_lock_irqsave(&ch->lock, irq_flags);
 756                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
 757                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 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         /* let registerer know that connection is disconnecting */
 779
 780         spin_lock_irqsave(&ch->lock, irq_flags);
 781         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 782                         !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 783                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
 784                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 785
 786                 xpc_disconnect_callout(ch, xpcDisconnecting);
 787
 788                 spin_lock_irqsave(&ch->lock, irq_flags);
 789                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
 790         }
 791         spin_unlock_irqrestore(&ch->lock, irq_flags);
 792
 793         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
 794                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
 795                         xpc_mark_partition_disengaged(part);
 796                         xpc_IPI_send_disengage(part);
 797                 }
 798         }
 799
 800         xpc_msgqueue_deref(ch);
 801
 802         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 803                 partid, ch_number);
 804
 805         xpc_part_deref(part);
 806         return 0;
 807 }
 808
 809
 810 /*
 811  * For each partition that XPC has established communications with, there is
 812  * a minimum of one kernel thread assigned to perform any operation that
 813  * may potentially sleep or block (basically the callouts to the asynchronous
 814  * functions registered via xpc_connect()).
 815  *
 816  * Additional kthreads are created and destroyed by XPC as the workload
 817  * demands.
 818  *
 819  * A kthread is assigned to one of the active channels that exists for a given
 820  * partition.
 821  */
 822 void
 823 xpc_create_kthreads(struct xpc_channel *ch, int needed,
 824                         int ignore_disconnecting)
 825 {
 826         unsigned long irq_flags;
 827         pid_t pid;
 828         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
 829         struct xpc_partition *part = &xpc_partitions[ch->partid];
 830
 831
 832         while (needed-- > 0) {
 833
 834                 /*
 835                  * The following is done on behalf of the newly created
 836                  * kthread. That kthread is responsible for doing the
 837                  * counterpart to the following before it exits.
 838                  */
 839                 if (ignore_disconnecting) {
 840                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
 841                                 /* kthreads assigned had gone to zero */
 842                                 BUG_ON(!(ch->flags &
 843                                         XPC_C_DISCONNECTINGCALLOUT_MADE));
 844                                 break;
 845                         }
 846
 847                 } else if (ch->flags & XPC_C_DISCONNECTING) {
 848                         break;
 849
 850                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1) {
 851                         if (atomic_inc_return(&part->nchannels_engaged) == 1)
 852                                 xpc_mark_partition_engaged(part);
 853                 }
 854                 (void) xpc_part_ref(part);
 855                 xpc_msgqueue_ref(ch);
 856
 857                 pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
 858                 if (pid < 0) {
 859                         /* the fork failed */
 860
 861                         /*
 862                          * NOTE: if (ignore_disconnecting &&
 863                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
 864                          * then we'll deadlock if all other kthreads assigned
 865                          * to this channel are blocked in the channel's
 866                          * registerer, because the only thing that will unblock
 867                          * them is the xpcDisconnecting callout that this
 868                          * failed kernel_thread would have made.
 869                          */
 870
 871                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 872                             atomic_dec_return(&part->nchannels_engaged) == 0) {
 873                                 xpc_mark_partition_disengaged(part);
 874                                 xpc_IPI_send_disengage(part);
 875                         }
 876                         xpc_msgqueue_deref(ch);
 877                         xpc_part_deref(part);
 878
 879                         if (atomic_read(&ch->kthreads_assigned) <
 880                                                 ch->kthreads_idle_limit) {
 881                                 /*
 882                                  * Flag this as an error only if we have an
 883                                  * insufficient #of kthreads for the channel
 884                                  * to function.
 885                                  */
 886                                 spin_lock_irqsave(&ch->lock, irq_flags);
 887                                 XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
 888                                                                 &irq_flags);
 889                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 890                         }
 891                         break;
 892                 }
 893
 894                 ch->kthreads_created++; // >>> temporary debug only!!!
 895         }
 896 }
 897
 898
 899 void
 900 xpc_disconnect_wait(int ch_number)
 901 {
 902         unsigned long irq_flags;
 903         partid_t partid;
 904         struct xpc_partition *part;
 905         struct xpc_channel *ch;
 906         int wakeup_channel_mgr;
 907
 908
 909         /* now wait for all callouts to the caller's function to cease */
 910         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 911                 part = &xpc_partitions[partid];
 912
 913                 if (!xpc_part_ref(part)) {
 914                         continue;
 915                 }
 916
 917                 ch = &part->channels[ch_number];
 918
 919                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
 920                         xpc_part_deref(part);
 921                         continue;
 922                 }
 923
 924                 wait_for_completion(&ch->wdisconnect_wait);
 925
 926                 spin_lock_irqsave(&ch->lock, irq_flags);
 927                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 928                 wakeup_channel_mgr = 0;
 929
 930                 if (ch->delayed_IPI_flags) {
 931                         if (part->act_state != XPC_P_DEACTIVATING) {
 932                                 spin_lock(&part->IPI_lock);
 933                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 934                                         ch->number, ch->delayed_IPI_flags);
 935                                 spin_unlock(&part->IPI_lock);
 936                                 wakeup_channel_mgr = 1;
 937                         }
 938                         ch->delayed_IPI_flags = 0;
 939                 }
 940
 941                 ch->flags &= ~XPC_C_WDISCONNECT;
 942                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 943
 944                 if (wakeup_channel_mgr) {
 945                         xpc_wakeup_channel_mgr(part);
 946                 }
 947
 948                 xpc_part_deref(part);
 949         }
 950 }
 951
 952
 953 static void
 954 xpc_do_exit(enum xpc_retval reason)
 955 {
 956         partid_t partid;
 957         int active_part_count, printed_waiting_msg = 0;
 958         struct xpc_partition *part;
 959         unsigned long printmsg_time, disengage_request_timeout = 0;
 960
 961
 962         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 963         DBUG_ON(xpc_exiting == 1);
 964
 965         /*
 966          * Let the heartbeat checker thread and the discovery thread
 967          * (if one is running) know that they should exit. Also wake up
 968          * the heartbeat checker thread in case it's sleeping.
 969          */
 970         xpc_exiting = 1;
 971         wake_up_interruptible(&xpc_act_IRQ_wq);
 972
 973         /* ignore all incoming interrupts */
 974         free_irq(SGI_XPC_ACTIVATE, NULL);
 975
 976         /* wait for the discovery thread to exit */
 977         wait_for_completion(&xpc_discovery_exited);
 978
 979         /* wait for the heartbeat checker thread to exit */
 980         wait_for_completion(&xpc_hb_checker_exited);
 981
 982
 983         /* sleep for a 1/3 of a second or so */
 984         (void) msleep_interruptible(300);
 985
 986
 987         /* wait for all partitions to become inactive */
 988
 989         printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 990         xpc_disengage_request_timedout = 0;
 991
 992         do {
 993                 active_part_count = 0;
 994
 995                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 996                         part = &xpc_partitions[partid];
 997
 998                         if (xpc_partition_disengaged(part) &&
 999                                         part->act_state == XPC_P_INACTIVE) {
1000                                 continue;
1001                         }
1002
1003                         active_part_count++;
1004
1005                         XPC_DEACTIVATE_PARTITION(part, reason);
1006
1007                         if (part->disengage_request_timeout >
1008                                                 disengage_request_timeout) {
1009                                 disengage_request_timeout =
1010                                                 part->disengage_request_timeout;
1011                         }
1012                 }
1013
1014                 if (xpc_partition_engaged(-1UL)) {
1015                         if (time_after(jiffies, printmsg_time)) {
1016                                 dev_info(xpc_part, "waiting for remote "
1017                                         "partitions to disengage, timeout in "
1018                                         "%ld seconds\n",
1019                                         (disengage_request_timeout - jiffies)
1020                                                                         / HZ);
1021                                 printmsg_time = jiffies +
1022                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
1023                                 printed_waiting_msg = 1;
1024                         }
1025
1026                 } else if (active_part_count > 0) {
1027                         if (printed_waiting_msg) {
1028                                 dev_info(xpc_part, "waiting for local partition"
1029                                         " to disengage\n");
1030                                 printed_waiting_msg = 0;
1031                         }
1032
1033                 } else {
1034                         if (!xpc_disengage_request_timedout) {
1035                                 dev_info(xpc_part, "all partitions have "
1036                                         "disengaged\n");
1037                         }
1038                         break;
1039                 }
1040
1041                 /* sleep for a 1/3 of a second or so */
1042                 (void) msleep_interruptible(300);
1043
1044         } while (1);
1045
1046         DBUG_ON(xpc_partition_engaged(-1UL));
1047
1048
1049         /* indicate to others that our reserved page is uninitialized */
1050         xpc_rsvd_page->vars_pa = 0;
1051
1052         /* now it's time to eliminate our heartbeat */
1053         del_timer_sync(&xpc_hb_timer);
1054         DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
1055
1056         if (reason == xpcUnloading) {
1057                 /* take ourselves off of the reboot_notifier_list */
1058                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1059
1060                 /* take ourselves off of the die_notifier list */
1061                 (void) unregister_die_notifier(&xpc_die_notifier);
1062         }
1063
1064         /* close down protections for IPI operations */
1065         xpc_restrict_IPI_ops();
1066
1067
1068         /* clear the interface to XPC's functions */
1069         xpc_clear_interface();
1070
1071         if (xpc_sysctl) {
1072                 unregister_sysctl_table(xpc_sysctl);
1073         }
1074
1075         kfree(xpc_remote_copy_buffer_base);
1076 }
1077
1078
1079 /*
1080  * This function is called when the system is being rebooted.
1081  */
1082 static int
1083 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1084 {
1085         enum xpc_retval reason;
1086
1087
1088         switch (event) {
1089         case SYS_RESTART:
1090                 reason = xpcSystemReboot;
1091                 break;
1092         case SYS_HALT:
1093                 reason = xpcSystemHalt;
1094                 break;
1095         case SYS_POWER_OFF:
1096                 reason = xpcSystemPoweroff;
1097                 break;
1098         default:
1099                 reason = xpcSystemGoingDown;
1100         }
1101
1102         xpc_do_exit(reason);
1103         return NOTIFY_DONE;
1104 }
1105
1106
1107 /*
1108  * Notify other partitions to disengage from all references to our memory.
1109  */
1110 static void
1111 xpc_die_disengage(void)
1112 {
1113         struct xpc_partition *part;
1114         partid_t partid;
1115         unsigned long engaged;
1116         long time, printmsg_time, disengage_request_timeout;
1117
1118
1119         /* keep xpc_hb_checker thread from doing anything (just in case) */
1120         xpc_exiting = 1;
1121
1122         xpc_vars->heartbeating_to_mask = 0;  /* indicate we're deactivated */
1123
1124         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1125                 part = &xpc_partitions[partid];
1126
1127                 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
1128                                                         remote_vars_version)) {
1129
1130                         /* just in case it was left set by an earlier XPC */
1131                         xpc_clear_partition_engaged(1UL << partid);
1132                         continue;
1133                 }
1134
1135                 if (xpc_partition_engaged(1UL << partid) ||
1136                                         part->act_state != XPC_P_INACTIVE) {
1137                         xpc_request_partition_disengage(part);
1138                         xpc_mark_partition_disengaged(part);
1139                         xpc_IPI_send_disengage(part);
1140                 }
1141         }
1142
1143         time = rtc_time();
1144         printmsg_time = time +
1145                 (XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
1146         disengage_request_timeout = time +
1147                 (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1148
1149         /* wait for all other partitions to disengage from us */
1150
1151         while (1) {
1152                 engaged = xpc_partition_engaged(-1UL);
1153                 if (!engaged) {
1154                         dev_info(xpc_part, "all partitions have disengaged\n");
1155                         break;
1156                 }
1157
1158                 time = rtc_time();
1159                 if (time >= disengage_request_timeout) {
1160                         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1161                                 if (engaged & (1UL << partid)) {
1162                                         dev_info(xpc_part, "disengage from "
1163                                                 "remote partition %d timed "
1164                                                 "out\n", partid);
1165                                 }
1166                         }
1167                         break;
1168                 }
1169
1170                 if (time >= printmsg_time) {
1171                         dev_info(xpc_part, "waiting for remote partitions to "
1172                                 "disengage, timeout in %ld seconds\n",
1173                                 (disengage_request_timeout - time) /
1174                                                 sn_rtc_cycles_per_second);
1175                         printmsg_time = time +
1176                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1177                                                 sn_rtc_cycles_per_second);
1178                 }
1179         }
1180 }
1181
1182
1183 /*
1184  * This function is called when the system is being restarted or halted due
1185  * to some sort of system failure. If this is the case we need to notify the
1186  * other partitions to disengage from all references to our memory.
1187  * This function can also be called when our heartbeater could be offlined
1188  * for a time. In this case we need to notify other partitions to not worry
1189  * about the lack of a heartbeat.
1190  */
1191 static int
1192 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1193 {
1194         switch (event) {
1195         case DIE_MACHINE_RESTART:
1196         case DIE_MACHINE_HALT:
1197                 xpc_die_disengage();
1198                 break;
1199
1200         case DIE_KDEBUG_ENTER:
1201                 /* Should lack of heartbeat be ignored by other partitions? */
1202                 if (!xpc_kdebug_ignore) {
1203                         break;
1204                 }
1205                 /* fall through */
1206         case DIE_MCA_MONARCH_ENTER:
1207         case DIE_INIT_MONARCH_ENTER:
1208                 xpc_vars->heartbeat++;
1209                 xpc_vars->heartbeat_offline = 1;
1210                 break;
1211
1212         case DIE_KDEBUG_LEAVE:
1213                 /* Is lack of heartbeat being ignored by other partitions? */
1214                 if (!xpc_kdebug_ignore) {
1215                         break;
1216                 }
1217                 /* fall through */
1218         case DIE_MCA_MONARCH_LEAVE:
1219         case DIE_INIT_MONARCH_LEAVE:
1220                 xpc_vars->heartbeat++;
1221                 xpc_vars->heartbeat_offline = 0;
1222                 break;
1223         }
1224
1225         return NOTIFY_DONE;
1226 }
1227
1228
1229 int __init
1230 xpc_init(void)
1231 {
1232         int ret;
1233         partid_t partid;
1234         struct xpc_partition *part;
1235         pid_t pid;
1236         size_t buf_size;
1237
1238
1239         if (!ia64_platform_is("sn2")) {
1240                 return -ENODEV;
1241         }
1242
1243
1244         buf_size = max(XPC_RP_VARS_SIZE,
1245                                 XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES);
1246         xpc_remote_copy_buffer = xpc_kmalloc_cacheline_aligned(buf_size,
1247                                      GFP_KERNEL, &xpc_remote_copy_buffer_base);
1248         if (xpc_remote_copy_buffer == NULL)
1249                 return -ENOMEM;
1250
1251         snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1252         snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1253
1254         xpc_sysctl = register_sysctl_table(xpc_sys_dir, 1);
1255
1256         /*
1257          * The first few fields of each entry of xpc_partitions[] need to
1258          * be initialized now so that calls to xpc_connect() and
1259          * xpc_disconnect() can be made prior to the activation of any remote
1260          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1261          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1262          * PARTITION HAS BEEN ACTIVATED.
1263          */
1264         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1265                 part = &xpc_partitions[partid];
1266
1267                 DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
1268
1269                 part->act_IRQ_rcvd = 0;
1270                 spin_lock_init(&part->act_lock);
1271                 part->act_state = XPC_P_INACTIVE;
1272                 XPC_SET_REASON(part, 0, 0);
1273
1274                 init_timer(&part->disengage_request_timer);
1275                 part->disengage_request_timer.function =
1276                                 xpc_timeout_partition_disengage_request;
1277                 part->disengage_request_timer.data = (unsigned long) part;
1278
1279                 part->setup_state = XPC_P_UNSET;
1280                 init_waitqueue_head(&part->teardown_wq);
1281                 atomic_set(&part->references, 0);
1282         }
1283
1284         /*
1285          * Open up protections for IPI operations (and AMO operations on
1286          * Shub 1.1 systems).
1287          */
1288         xpc_allow_IPI_ops();
1289
1290         /*
1291          * Interrupts being processed will increment this atomic variable and
1292          * awaken the heartbeat thread which will process the interrupts.
1293          */
1294         atomic_set(&xpc_act_IRQ_rcvd, 0);
1295
1296         /*
1297          * This is safe to do before the xpc_hb_checker thread has started
1298          * because the handler releases a wait queue.  If an interrupt is
1299          * received before the thread is waiting, it will not go to sleep,
1300          * but rather immediately process the interrupt.
1301          */
1302         ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1303                                                         "xpc hb", NULL);
1304         if (ret != 0) {
1305                 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1306                         "errno=%d\n", -ret);
1307
1308                 xpc_restrict_IPI_ops();
1309
1310                 if (xpc_sysctl) {
1311                         unregister_sysctl_table(xpc_sysctl);
1312                 }
1313
1314                 kfree(xpc_remote_copy_buffer_base);
1315                 return -EBUSY;
1316         }
1317
1318         /*
1319          * Fill the partition reserved page with the information needed by
1320          * other partitions to discover we are alive and establish initial
1321          * communications.
1322          */
1323         xpc_rsvd_page = xpc_rsvd_page_init();
1324         if (xpc_rsvd_page == NULL) {
1325                 dev_err(xpc_part, "could not setup our reserved page\n");
1326
1327                 free_irq(SGI_XPC_ACTIVATE, NULL);
1328                 xpc_restrict_IPI_ops();
1329
1330                 if (xpc_sysctl) {
1331                         unregister_sysctl_table(xpc_sysctl);
1332                 }
1333
1334                 kfree(xpc_remote_copy_buffer_base);
1335                 return -EBUSY;
1336         }
1337
1338
1339         /* add ourselves to the reboot_notifier_list */
1340         ret = register_reboot_notifier(&xpc_reboot_notifier);
1341         if (ret != 0) {
1342                 dev_warn(xpc_part, "can't register reboot notifier\n");
1343         }
1344
1345         /* add ourselves to the die_notifier list (i.e., ia64die_chain) */
1346         ret = register_die_notifier(&xpc_die_notifier);
1347         if (ret != 0) {
1348                 dev_warn(xpc_part, "can't register die notifier\n");
1349         }
1350
1351
1352         /*
1353          * Set the beating to other partitions into motion.  This is
1354          * the last requirement for other partitions' discovery to
1355          * initiate communications with us.
1356          */
1357         init_timer(&xpc_hb_timer);
1358         xpc_hb_timer.function = xpc_hb_beater;
1359         xpc_hb_beater(0);
1360
1361
1362         /*
1363          * The real work-horse behind xpc.  This processes incoming
1364          * interrupts and monitors remote heartbeats.
1365          */
1366         pid = kernel_thread(xpc_hb_checker, NULL, 0);
1367         if (pid < 0) {
1368                 dev_err(xpc_part, "failed while forking hb check thread\n");
1369
1370                 /* indicate to others that our reserved page is uninitialized */
1371                 xpc_rsvd_page->vars_pa = 0;
1372
1373                 /* take ourselves off of the reboot_notifier_list */
1374                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1375
1376                 /* take ourselves off of the die_notifier list */
1377                 (void) unregister_die_notifier(&xpc_die_notifier);
1378
1379                 del_timer_sync(&xpc_hb_timer);
1380                 free_irq(SGI_XPC_ACTIVATE, NULL);
1381                 xpc_restrict_IPI_ops();
1382
1383                 if (xpc_sysctl) {
1384                         unregister_sysctl_table(xpc_sysctl);
1385                 }
1386
1387                 kfree(xpc_remote_copy_buffer_base);
1388                 return -EBUSY;
1389         }
1390
1391
1392         /*
1393          * Startup a thread that will attempt to discover other partitions to
1394          * activate based on info provided by SAL. This new thread is short
1395          * lived and will exit once discovery is complete.
1396          */
1397         pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
1398         if (pid < 0) {
1399                 dev_err(xpc_part, "failed while forking discovery thread\n");
1400
1401                 /* mark this new thread as a non-starter */
1402                 complete(&xpc_discovery_exited);
1403
1404                 xpc_do_exit(xpcUnloading);
1405                 return -EBUSY;
1406         }
1407
1408
1409         /* set the interface to point at XPC's functions */
1410         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1411                           xpc_initiate_allocate, xpc_initiate_send,
1412                           xpc_initiate_send_notify, xpc_initiate_received,
1413                           xpc_initiate_partid_to_nasids);
1414
1415         return 0;
1416 }
1417 module_init(xpc_init);
1418
1419
1420 void __exit
1421 xpc_exit(void)
1422 {
1423         xpc_do_exit(xpcUnloading);
1424 }
1425 module_exit(xpc_exit);
1426
1427
1428 MODULE_AUTHOR("Silicon Graphics, Inc.");
1429 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1430 MODULE_LICENSE("GPL");
1431
1432 module_param(xpc_hb_interval, int, 0);
1433 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1434                 "heartbeat increments.");
1435
1436 module_param(xpc_hb_check_interval, int, 0);
1437 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1438                 "heartbeat checks.");
1439
1440 module_param(xpc_disengage_request_timelimit, int, 0);
1441 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1442                 "for disengage request to complete.");
1443
1444 module_param(xpc_kdebug_ignore, int, 0);
1445 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1446                 "other partitions when dropping into kdebug.");
1447