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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 <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_MUTEX_LOCKED(xpc_hb_checker_exited);
 181
 182 /* notification that the xpc_discovery thread has exited */
 183 static DECLARE_MUTEX_LOCKED(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, struct pt_regs *regs)
 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         up(&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         up(&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         pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
 578
 579         DBUG_ON(part->act_state != XPC_P_INACTIVE);
 580
 581         if (pid > 0) {
 582                 part->act_state = XPC_P_ACTIVATION_REQ;
 583                 XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
 584         } else {
 585                 XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
 586         }
 587
 588         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 589 }
 590
 591
 592 /*
 593  * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
 594  * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
 595  * than one partition, we use an AMO_t structure per partition to indicate
 596  * whether a partition has sent an IPI or not.  >>> If it has, then wake up the
 597  * associated kthread to handle it.
 598  *
 599  * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
 600  * running on other partitions.
 601  *
 602  * Noteworthy Arguments:
 603  *
 604  *      irq - Interrupt ReQuest number. NOT USED.
 605  *
 606  *      dev_id - partid of IPI's potential sender.
 607  *
 608  *      regs - processor's context before the processor entered
 609  *             interrupt code. NOT USED.
 610  */
 611 irqreturn_t
 612 xpc_notify_IRQ_handler(int irq, void *dev_id, struct pt_regs *regs)
 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);
 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_CONNECTCALLOUT)) {
 750                         ch->flags |= XPC_C_CONNECTCALLOUT;
 751                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 752
 753                         xpc_connected_callout(ch);
 754
 755                         /*
 756                          * It is possible that while the callout was being
 757                          * made that the remote partition sent some messages.
 758                          * If that is the case, we may need to activate
 759                          * additional kthreads to help deliver them. We only
 760                          * need one less than total #of messages to deliver.
 761                          */
 762                         n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
 763                         if (n_needed > 0 &&
 764                                         !(ch->flags & XPC_C_DISCONNECTING)) {
 765                                 xpc_activate_kthreads(ch, n_needed);
 766                         }
 767                 } else {
 768                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 769                 }
 770
 771                 xpc_kthread_waitmsgs(part, ch);
 772         }
 773
 774         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
 775                 spin_lock_irqsave(&ch->lock, irq_flags);
 776                 if ((ch->flags & XPC_C_CONNECTCALLOUT) &&
 777                                 !(ch->flags & XPC_C_DISCONNECTCALLOUT)) {
 778                         ch->flags |= XPC_C_DISCONNECTCALLOUT;
 779                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 780
 781                         xpc_disconnect_callout(ch, xpcDisconnecting);
 782                 } else {
 783                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 784                 }
 785                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
 786                         xpc_mark_partition_disengaged(part);
 787                         xpc_IPI_send_disengage(part);
 788                 }
 789         }
 790
 791
 792         xpc_msgqueue_deref(ch);
 793
 794         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 795                 partid, ch_number);
 796
 797         xpc_part_deref(part);
 798         return 0;
 799 }
 800
 801
 802 /*
 803  * For each partition that XPC has established communications with, there is
 804  * a minimum of one kernel thread assigned to perform any operation that
 805  * may potentially sleep or block (basically the callouts to the asynchronous
 806  * functions registered via xpc_connect()).
 807  *
 808  * Additional kthreads are created and destroyed by XPC as the workload
 809  * demands.
 810  *
 811  * A kthread is assigned to one of the active channels that exists for a given
 812  * partition.
 813  */
 814 void
 815 xpc_create_kthreads(struct xpc_channel *ch, int needed)
 816 {
 817         unsigned long irq_flags;
 818         pid_t pid;
 819         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
 820         struct xpc_partition *part = &xpc_partitions[ch->partid];
 821
 822
 823         while (needed-- > 0) {
 824
 825                 /*
 826                  * The following is done on behalf of the newly created
 827                  * kthread. That kthread is responsible for doing the
 828                  * counterpart to the following before it exits.
 829                  */
 830                 (void) xpc_part_ref(part);
 831                 xpc_msgqueue_ref(ch);
 832                 if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
 833                     atomic_inc_return(&part->nchannels_engaged) == 1) {
 834                         xpc_mark_partition_engaged(part);
 835                 }
 836
 837                 pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
 838                 if (pid < 0) {
 839                         /* the fork failed */
 840                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 841                             atomic_dec_return(&part->nchannels_engaged) == 0) {
 842                                 xpc_mark_partition_disengaged(part);
 843                                 xpc_IPI_send_disengage(part);
 844                         }
 845                         xpc_msgqueue_deref(ch);
 846                         xpc_part_deref(part);
 847
 848                         if (atomic_read(&ch->kthreads_assigned) <
 849                                                 ch->kthreads_idle_limit) {
 850                                 /*
 851                                  * Flag this as an error only if we have an
 852                                  * insufficient #of kthreads for the channel
 853                                  * to function.
 854                                  *
 855                                  * No xpc_msgqueue_ref() is needed here since
 856                                  * the channel mgr is doing this.
 857                                  */
 858                                 spin_lock_irqsave(&ch->lock, irq_flags);
 859                                 XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
 860                                                                 &irq_flags);
 861                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 862                         }
 863                         break;
 864                 }
 865
 866                 ch->kthreads_created++; // >>> temporary debug only!!!
 867         }
 868 }
 869
 870
 871 void
 872 xpc_disconnect_wait(int ch_number)
 873 {
 874         unsigned long irq_flags;
 875         partid_t partid;
 876         struct xpc_partition *part;
 877         struct xpc_channel *ch;
 878         int wakeup_channel_mgr;
 879
 880
 881         /* now wait for all callouts to the caller's function to cease */
 882         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 883                 part = &xpc_partitions[partid];
 884
 885                 if (!xpc_part_ref(part)) {
 886                         continue;
 887                 }
 888
 889                 ch = &part->channels[ch_number];
 890
 891                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
 892                         xpc_part_deref(part);
 893                         continue;
 894                 }
 895
 896                 (void) down(&ch->wdisconnect_sema);
 897
 898                 spin_lock_irqsave(&ch->lock, irq_flags);
 899                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 900                 wakeup_channel_mgr = 0;
 901
 902                 if (ch->delayed_IPI_flags) {
 903                         if (part->act_state != XPC_P_DEACTIVATING) {
 904                                 spin_lock(&part->IPI_lock);
 905                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 906                                         ch->number, ch->delayed_IPI_flags);
 907                                 spin_unlock(&part->IPI_lock);
 908                                 wakeup_channel_mgr = 1;
 909                         }
 910                         ch->delayed_IPI_flags = 0;
 911                 }
 912
 913                 ch->flags &= ~XPC_C_WDISCONNECT;
 914                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 915
 916                 if (wakeup_channel_mgr) {
 917                         xpc_wakeup_channel_mgr(part);
 918                 }
 919
 920                 xpc_part_deref(part);
 921         }
 922 }
 923
 924
 925 static void
 926 xpc_do_exit(enum xpc_retval reason)
 927 {
 928         partid_t partid;
 929         int active_part_count, printed_waiting_msg = 0;
 930         struct xpc_partition *part;
 931         unsigned long printmsg_time, disengage_request_timeout = 0;
 932
 933
 934         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 935         DBUG_ON(xpc_exiting == 1);
 936
 937         /*
 938          * Let the heartbeat checker thread and the discovery thread
 939          * (if one is running) know that they should exit. Also wake up
 940          * the heartbeat checker thread in case it's sleeping.
 941          */
 942         xpc_exiting = 1;
 943         wake_up_interruptible(&xpc_act_IRQ_wq);
 944
 945         /* ignore all incoming interrupts */
 946         free_irq(SGI_XPC_ACTIVATE, NULL);
 947
 948         /* wait for the discovery thread to exit */
 949         down(&xpc_discovery_exited);
 950
 951         /* wait for the heartbeat checker thread to exit */
 952         down(&xpc_hb_checker_exited);
 953
 954
 955         /* sleep for a 1/3 of a second or so */
 956         (void) msleep_interruptible(300);
 957
 958
 959         /* wait for all partitions to become inactive */
 960
 961         printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 962         xpc_disengage_request_timedout = 0;
 963
 964         do {
 965                 active_part_count = 0;
 966
 967                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 968                         part = &xpc_partitions[partid];
 969
 970                         if (xpc_partition_disengaged(part) &&
 971                                         part->act_state == XPC_P_INACTIVE) {
 972                                 continue;
 973                         }
 974
 975                         active_part_count++;
 976
 977                         XPC_DEACTIVATE_PARTITION(part, reason);
 978
 979                         if (part->disengage_request_timeout >
 980                                                 disengage_request_timeout) {
 981                                 disengage_request_timeout =
 982                                                 part->disengage_request_timeout;
 983                         }
 984                 }
 985
 986                 if (xpc_partition_engaged(-1UL)) {
 987                         if (time_after(jiffies, printmsg_time)) {
 988                                 dev_info(xpc_part, "waiting for remote "
 989                                         "partitions to disengage, timeout in "
 990                                         "%ld seconds\n",
 991                                         (disengage_request_timeout - jiffies)
 992                                                                         / HZ);
 993                                 printmsg_time = jiffies +
 994                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 995                                 printed_waiting_msg = 1;
 996                         }
 997
 998                 } else if (active_part_count > 0) {
 999                         if (printed_waiting_msg) {
1000                                 dev_info(xpc_part, "waiting for local partition"
1001                                         " to disengage\n");
1002                                 printed_waiting_msg = 0;
1003                         }
1004
1005                 } else {
1006                         if (!xpc_disengage_request_timedout) {
1007                                 dev_info(xpc_part, "all partitions have "
1008                                         "disengaged\n");
1009                         }
1010                         break;
1011                 }
1012
1013                 /* sleep for a 1/3 of a second or so */
1014                 (void) msleep_interruptible(300);
1015
1016         } while (1);
1017
1018         DBUG_ON(xpc_partition_engaged(-1UL));
1019
1020
1021         /* indicate to others that our reserved page is uninitialized */
1022         xpc_rsvd_page->vars_pa = 0;
1023
1024         /* now it's time to eliminate our heartbeat */
1025         del_timer_sync(&xpc_hb_timer);
1026         DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
1027
1028         if (reason == xpcUnloading) {
1029                 /* take ourselves off of the reboot_notifier_list */
1030                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1031
1032                 /* take ourselves off of the die_notifier list */
1033                 (void) unregister_die_notifier(&xpc_die_notifier);
1034         }
1035
1036         /* close down protections for IPI operations */
1037         xpc_restrict_IPI_ops();
1038
1039
1040         /* clear the interface to XPC's functions */
1041         xpc_clear_interface();
1042
1043         if (xpc_sysctl) {
1044                 unregister_sysctl_table(xpc_sysctl);
1045         }
1046 }
1047
1048
1049 /*
1050  * This function is called when the system is being rebooted.
1051  */
1052 static int
1053 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1054 {
1055         enum xpc_retval reason;
1056
1057
1058         switch (event) {
1059         case SYS_RESTART:
1060                 reason = xpcSystemReboot;
1061                 break;
1062         case SYS_HALT:
1063                 reason = xpcSystemHalt;
1064                 break;
1065         case SYS_POWER_OFF:
1066                 reason = xpcSystemPoweroff;
1067                 break;
1068         default:
1069                 reason = xpcSystemGoingDown;
1070         }
1071
1072         xpc_do_exit(reason);
1073         return NOTIFY_DONE;
1074 }
1075
1076
1077 /*
1078  * Notify other partitions to disengage from all references to our memory.
1079  */
1080 static void
1081 xpc_die_disengage(void)
1082 {
1083         struct xpc_partition *part;
1084         partid_t partid;
1085         unsigned long engaged;
1086         long time, printmsg_time, disengage_request_timeout;
1087
1088
1089         /* keep xpc_hb_checker thread from doing anything (just in case) */
1090         xpc_exiting = 1;
1091
1092         xpc_vars->heartbeating_to_mask = 0;  /* indicate we're deactivated */
1093
1094         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1095                 part = &xpc_partitions[partid];
1096
1097                 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
1098                                                         remote_vars_version)) {
1099
1100                         /* just in case it was left set by an earlier XPC */
1101                         xpc_clear_partition_engaged(1UL << partid);
1102                         continue;
1103                 }
1104
1105                 if (xpc_partition_engaged(1UL << partid) ||
1106                                         part->act_state != XPC_P_INACTIVE) {
1107                         xpc_request_partition_disengage(part);
1108                         xpc_mark_partition_disengaged(part);
1109                         xpc_IPI_send_disengage(part);
1110                 }
1111         }
1112
1113         time = rtc_time();
1114         printmsg_time = time +
1115                 (XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
1116         disengage_request_timeout = time +
1117                 (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1118
1119         /* wait for all other partitions to disengage from us */
1120
1121         while (1) {
1122                 engaged = xpc_partition_engaged(-1UL);
1123                 if (!engaged) {
1124                         dev_info(xpc_part, "all partitions have disengaged\n");
1125                         break;
1126                 }
1127
1128                 time = rtc_time();
1129                 if (time >= disengage_request_timeout) {
1130                         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1131                                 if (engaged & (1UL << partid)) {
1132                                         dev_info(xpc_part, "disengage from "
1133                                                 "remote partition %d timed "
1134                                                 "out\n", partid);
1135                                 }
1136                         }
1137                         break;
1138                 }
1139
1140                 if (time >= printmsg_time) {
1141                         dev_info(xpc_part, "waiting for remote partitions to "
1142                                 "disengage, timeout in %ld seconds\n",
1143                                 (disengage_request_timeout - time) /
1144                                                 sn_rtc_cycles_per_second);
1145                         printmsg_time = time +
1146                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1147                                                 sn_rtc_cycles_per_second);
1148                 }
1149         }
1150 }
1151
1152
1153 /*
1154  * This function is called when the system is being restarted or halted due
1155  * to some sort of system failure. If this is the case we need to notify the
1156  * other partitions to disengage from all references to our memory.
1157  * This function can also be called when our heartbeater could be offlined
1158  * for a time. In this case we need to notify other partitions to not worry
1159  * about the lack of a heartbeat.
1160  */
1161 static int
1162 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1163 {
1164         switch (event) {
1165         case DIE_MACHINE_RESTART:
1166         case DIE_MACHINE_HALT:
1167                 xpc_die_disengage();
1168                 break;
1169
1170         case DIE_KDEBUG_ENTER:
1171                 /* Should lack of heartbeat be ignored by other partitions? */
1172                 if (!xpc_kdebug_ignore) {
1173                         break;
1174                 }
1175                 /* fall through */
1176         case DIE_MCA_MONARCH_ENTER:
1177         case DIE_INIT_MONARCH_ENTER:
1178                 xpc_vars->heartbeat++;
1179                 xpc_vars->heartbeat_offline = 1;
1180                 break;
1181
1182         case DIE_KDEBUG_LEAVE:
1183                 /* Is lack of heartbeat being ignored by other partitions? */
1184                 if (!xpc_kdebug_ignore) {
1185                         break;
1186                 }
1187                 /* fall through */
1188         case DIE_MCA_MONARCH_LEAVE:
1189         case DIE_INIT_MONARCH_LEAVE:
1190                 xpc_vars->heartbeat++;
1191                 xpc_vars->heartbeat_offline = 0;
1192                 break;
1193         }
1194
1195         return NOTIFY_DONE;
1196 }
1197
1198
1199 int __init
1200 xpc_init(void)
1201 {
1202         int ret;
1203         partid_t partid;
1204         struct xpc_partition *part;
1205         pid_t pid;
1206
1207
1208         if (!ia64_platform_is("sn2")) {
1209                 return -ENODEV;
1210         }
1211
1212         /*
1213          * xpc_remote_copy_buffer is used as a temporary buffer for bte_copy'ng
1214          * various portions of a partition's reserved page. Its size is based
1215          * on the size of the reserved page header and part_nasids mask. So we
1216          * need to ensure that the other items will fit as well.
1217          */
1218         if (XPC_RP_VARS_SIZE > XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES) {
1219                 dev_err(xpc_part, "xpc_remote_copy_buffer is not big enough\n");
1220                 return -EPERM;
1221         }
1222         DBUG_ON((u64) xpc_remote_copy_buffer !=
1223                                 L1_CACHE_ALIGN((u64) xpc_remote_copy_buffer));
1224
1225         snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1226         snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1227
1228         xpc_sysctl = register_sysctl_table(xpc_sys_dir, 1);
1229
1230         /*
1231          * The first few fields of each entry of xpc_partitions[] need to
1232          * be initialized now so that calls to xpc_connect() and
1233          * xpc_disconnect() can be made prior to the activation of any remote
1234          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1235          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1236          * PARTITION HAS BEEN ACTIVATED.
1237          */
1238         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1239                 part = &xpc_partitions[partid];
1240
1241                 DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
1242
1243                 part->act_IRQ_rcvd = 0;
1244                 spin_lock_init(&part->act_lock);
1245                 part->act_state = XPC_P_INACTIVE;
1246                 XPC_SET_REASON(part, 0, 0);
1247
1248                 init_timer(&part->disengage_request_timer);
1249                 part->disengage_request_timer.function =
1250                                 xpc_timeout_partition_disengage_request;
1251                 part->disengage_request_timer.data = (unsigned long) part;
1252
1253                 part->setup_state = XPC_P_UNSET;
1254                 init_waitqueue_head(&part->teardown_wq);
1255                 atomic_set(&part->references, 0);
1256         }
1257
1258         /*
1259          * Open up protections for IPI operations (and AMO operations on
1260          * Shub 1.1 systems).
1261          */
1262         xpc_allow_IPI_ops();
1263
1264         /*
1265          * Interrupts being processed will increment this atomic variable and
1266          * awaken the heartbeat thread which will process the interrupts.
1267          */
1268         atomic_set(&xpc_act_IRQ_rcvd, 0);
1269
1270         /*
1271          * This is safe to do before the xpc_hb_checker thread has started
1272          * because the handler releases a wait queue.  If an interrupt is
1273          * received before the thread is waiting, it will not go to sleep,
1274          * but rather immediately process the interrupt.
1275          */
1276         ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1277                                                         "xpc hb", NULL);
1278         if (ret != 0) {
1279                 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1280                         "errno=%d\n", -ret);
1281
1282                 xpc_restrict_IPI_ops();
1283
1284                 if (xpc_sysctl) {
1285                         unregister_sysctl_table(xpc_sysctl);
1286                 }
1287                 return -EBUSY;
1288         }
1289
1290         /*
1291          * Fill the partition reserved page with the information needed by
1292          * other partitions to discover we are alive and establish initial
1293          * communications.
1294          */
1295         xpc_rsvd_page = xpc_rsvd_page_init();
1296         if (xpc_rsvd_page == NULL) {
1297                 dev_err(xpc_part, "could not setup our reserved page\n");
1298
1299                 free_irq(SGI_XPC_ACTIVATE, NULL);
1300                 xpc_restrict_IPI_ops();
1301
1302                 if (xpc_sysctl) {
1303                         unregister_sysctl_table(xpc_sysctl);
1304                 }
1305                 return -EBUSY;
1306         }
1307
1308
1309         /* add ourselves to the reboot_notifier_list */
1310         ret = register_reboot_notifier(&xpc_reboot_notifier);
1311         if (ret != 0) {
1312                 dev_warn(xpc_part, "can't register reboot notifier\n");
1313         }
1314
1315         /* add ourselves to the die_notifier list (i.e., ia64die_chain) */
1316         ret = register_die_notifier(&xpc_die_notifier);
1317         if (ret != 0) {
1318                 dev_warn(xpc_part, "can't register die notifier\n");
1319         }
1320
1321
1322         /*
1323          * Set the beating to other partitions into motion.  This is
1324          * the last requirement for other partitions' discovery to
1325          * initiate communications with us.
1326          */
1327         init_timer(&xpc_hb_timer);
1328         xpc_hb_timer.function = xpc_hb_beater;
1329         xpc_hb_beater(0);
1330
1331
1332         /*
1333          * The real work-horse behind xpc.  This processes incoming
1334          * interrupts and monitors remote heartbeats.
1335          */
1336         pid = kernel_thread(xpc_hb_checker, NULL, 0);
1337         if (pid < 0) {
1338                 dev_err(xpc_part, "failed while forking hb check thread\n");
1339
1340                 /* indicate to others that our reserved page is uninitialized */
1341                 xpc_rsvd_page->vars_pa = 0;
1342
1343                 /* take ourselves off of the reboot_notifier_list */
1344                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1345
1346                 /* take ourselves off of the die_notifier list */
1347                 (void) unregister_die_notifier(&xpc_die_notifier);
1348
1349                 del_timer_sync(&xpc_hb_timer);
1350                 free_irq(SGI_XPC_ACTIVATE, NULL);
1351                 xpc_restrict_IPI_ops();
1352
1353                 if (xpc_sysctl) {
1354                         unregister_sysctl_table(xpc_sysctl);
1355                 }
1356                 return -EBUSY;
1357         }
1358
1359
1360         /*
1361          * Startup a thread that will attempt to discover other partitions to
1362          * activate based on info provided by SAL. This new thread is short
1363          * lived and will exit once discovery is complete.
1364          */
1365         pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
1366         if (pid < 0) {
1367                 dev_err(xpc_part, "failed while forking discovery thread\n");
1368
1369                 /* mark this new thread as a non-starter */
1370                 up(&xpc_discovery_exited);
1371
1372                 xpc_do_exit(xpcUnloading);
1373                 return -EBUSY;
1374         }
1375
1376
1377         /* set the interface to point at XPC's functions */
1378         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1379                           xpc_initiate_allocate, xpc_initiate_send,
1380                           xpc_initiate_send_notify, xpc_initiate_received,
1381                           xpc_initiate_partid_to_nasids);
1382
1383         return 0;
1384 }
1385 module_init(xpc_init);
1386
1387
1388 void __exit
1389 xpc_exit(void)
1390 {
1391         xpc_do_exit(xpcUnloading);
1392 }
1393 module_exit(xpc_exit);
1394
1395
1396 MODULE_AUTHOR("Silicon Graphics, Inc.");
1397 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1398 MODULE_LICENSE("GPL");
1399
1400 module_param(xpc_hb_interval, int, 0);
1401 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1402                 "heartbeat increments.");
1403
1404 module_param(xpc_hb_check_interval, int, 0);
1405 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1406                 "heartbeat checks.");
1407
1408 module_param(xpc_disengage_request_timelimit, int, 0);
1409 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1410                 "for disengage request to complete.");
1411
1412 module_param(xpc_kdebug_ignore, int, 0);
1413 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1414                 "other partitions when dropping into kdebug.");
1415