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                 NULL,
 112                 &sysctl_intvec,
 113                 NULL,
 114                 &xpc_hb_min_interval,
 115                 &xpc_hb_max_interval
 116         },
 117         {
 118                 2,
 119                 "hb_check_interval",
 120                 &xpc_hb_check_interval,
 121                 sizeof(int),
 122                 0644,
 123                 NULL,
 124                 &proc_dointvec_minmax,
 125                 NULL,
 126                 &sysctl_intvec,
 127                 NULL,
 128                 &xpc_hb_check_min_interval,
 129                 &xpc_hb_check_max_interval
 130         },
 131         {0}
 132 };
 133 static ctl_table xpc_sys_xpc_dir[] = {
 134         {
 135                 1,
 136                 "hb",
 137                 NULL,
 138                 0,
 139                 0555,
 140                 xpc_sys_xpc_hb_dir
 141         },
 142         {
 143                 2,
 144                 "disengage_request_timelimit",
 145                 &xpc_disengage_request_timelimit,
 146                 sizeof(int),
 147                 0644,
 148                 NULL,
 149                 &proc_dointvec_minmax,
 150                 NULL,
 151                 &sysctl_intvec,
 152                 NULL,
 153                 &xpc_disengage_request_min_timelimit,
 154                 &xpc_disengage_request_max_timelimit
 155         },
 156         {0}
 157 };
 158 static ctl_table xpc_sys_dir[] = {
 159         {
 160                 1,
 161                 "xpc",
 162                 NULL,
 163                 0,
 164                 0555,
 165                 xpc_sys_xpc_dir
 166         },
 167         {0}
 168 };
 169 static struct ctl_table_header *xpc_sysctl;
 170
 171 /* non-zero if any remote partition disengage request was timed out */
 172 int xpc_disengage_request_timedout;
 173
 174 /* #of IRQs received */
 175 static atomic_t xpc_act_IRQ_rcvd;
 176
 177 /* IRQ handler notifies this wait queue on receipt of an IRQ */
 178 static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
 179
 180 static unsigned long xpc_hb_check_timeout;
 181
 182 /* notification that the xpc_hb_checker thread has exited */
 183 static DECLARE_COMPLETION(xpc_hb_checker_exited);
 184
 185 /* notification that the xpc_discovery thread has exited */
 186 static DECLARE_COMPLETION(xpc_discovery_exited);
 187
 188
 189 static struct timer_list xpc_hb_timer;
 190
 191
 192 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
 193
 194
 195 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
 196 static struct notifier_block xpc_reboot_notifier = {
 197         .notifier_call = xpc_system_reboot,
 198 };
 199
 200 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
 201 static struct notifier_block xpc_die_notifier = {
 202         .notifier_call = xpc_system_die,
 203 };
 204
 205
 206 /*
 207  * Timer function to enforce the timelimit on the partition disengage request.
 208  */
 209 static void
 210 xpc_timeout_partition_disengage_request(unsigned long data)
 211 {
 212         struct xpc_partition *part = (struct xpc_partition *) data;
 213
 214
 215         DBUG_ON(jiffies < part->disengage_request_timeout);
 216
 217         (void) xpc_partition_disengaged(part);
 218
 219         DBUG_ON(part->disengage_request_timeout != 0);
 220         DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
 221 }
 222
 223
 224 /*
 225  * Notify the heartbeat check thread that an IRQ has been received.
 226  */
 227 static irqreturn_t
 228 xpc_act_IRQ_handler(int irq, void *dev_id)
 229 {
 230         atomic_inc(&xpc_act_IRQ_rcvd);
 231         wake_up_interruptible(&xpc_act_IRQ_wq);
 232         return IRQ_HANDLED;
 233 }
 234
 235
 236 /*
 237  * Timer to produce the heartbeat.  The timer structures function is
 238  * already set when this is initially called.  A tunable is used to
 239  * specify when the next timeout should occur.
 240  */
 241 static void
 242 xpc_hb_beater(unsigned long dummy)
 243 {
 244         xpc_vars->heartbeat++;
 245
 246         if (jiffies >= xpc_hb_check_timeout) {
 247                 wake_up_interruptible(&xpc_act_IRQ_wq);
 248         }
 249
 250         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
 251         add_timer(&xpc_hb_timer);
 252 }
 253
 254
 255 /*
 256  * This thread is responsible for nearly all of the partition
 257  * activation/deactivation.
 258  */
 259 static int
 260 xpc_hb_checker(void *ignore)
 261 {
 262         int last_IRQ_count = 0;
 263         int new_IRQ_count;
 264         int force_IRQ=0;
 265
 266
 267         /* this thread was marked active by xpc_hb_init() */
 268
 269         daemonize(XPC_HB_CHECK_THREAD_NAME);
 270
 271         set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
 272
 273         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
 274
 275         while (!(volatile int) xpc_exiting) {
 276
 277                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
 278                         "been received\n",
 279                         (int) (xpc_hb_check_timeout - jiffies),
 280                         atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
 281
 282
 283                 /* checking of remote heartbeats is skewed by IRQ handling */
 284                 if (jiffies >= xpc_hb_check_timeout) {
 285                         dev_dbg(xpc_part, "checking remote heartbeats\n");
 286                         xpc_check_remote_hb();
 287
 288                         /*
 289                          * We need to periodically recheck to ensure no
 290                          * IPI/AMO pairs have been missed.  That check
 291                          * must always reset xpc_hb_check_timeout.
 292                          */
 293                         force_IRQ = 1;
 294                 }
 295
 296
 297                 /* check for outstanding IRQs */
 298                 new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
 299                 if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
 300                         force_IRQ = 0;
 301
 302                         dev_dbg(xpc_part, "found an IRQ to process; will be "
 303                                 "resetting xpc_hb_check_timeout\n");
 304
 305                         last_IRQ_count += xpc_identify_act_IRQ_sender();
 306                         if (last_IRQ_count < new_IRQ_count) {
 307                                 /* retry once to help avoid missing AMO */
 308                                 (void) xpc_identify_act_IRQ_sender();
 309                         }
 310                         last_IRQ_count = new_IRQ_count;
 311
 312                         xpc_hb_check_timeout = jiffies +
 313                                            (xpc_hb_check_interval * HZ);
 314                 }
 315
 316                 /* wait for IRQ or timeout */
 317                 (void) wait_event_interruptible(xpc_act_IRQ_wq,
 318                             (last_IRQ_count < atomic_read(&xpc_act_IRQ_rcvd) ||
 319                                         jiffies >= xpc_hb_check_timeout ||
 320                                                 (volatile int) xpc_exiting));
 321         }
 322
 323         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 324
 325
 326         /* mark this thread as having exited */
 327         complete(&xpc_hb_checker_exited);
 328         return 0;
 329 }
 330
 331
 332 /*
 333  * This thread will attempt to discover other partitions to activate
 334  * based on info provided by SAL. This new thread is short lived and
 335  * will exit once discovery is complete.
 336  */
 337 static int
 338 xpc_initiate_discovery(void *ignore)
 339 {
 340         daemonize(XPC_DISCOVERY_THREAD_NAME);
 341
 342         xpc_discovery();
 343
 344         dev_dbg(xpc_part, "discovery thread is exiting\n");
 345
 346         /* mark this thread as having exited */
 347         complete(&xpc_discovery_exited);
 348         return 0;
 349 }
 350
 351
 352 /*
 353  * Establish first contact with the remote partititon. This involves pulling
 354  * the XPC per partition variables from the remote partition and waiting for
 355  * the remote partition to pull ours.
 356  */
 357 static enum xpc_retval
 358 xpc_make_first_contact(struct xpc_partition *part)
 359 {
 360         enum xpc_retval ret;
 361
 362
 363         while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
 364                 if (ret != xpcRetry) {
 365                         XPC_DEACTIVATE_PARTITION(part, ret);
 366                         return ret;
 367                 }
 368
 369                 dev_dbg(xpc_chan, "waiting to make first contact with "
 370                         "partition %d\n", XPC_PARTID(part));
 371
 372                 /* wait a 1/4 of a second or so */
 373                 (void) msleep_interruptible(250);
 374
 375                 if (part->act_state == XPC_P_DEACTIVATING) {
 376                         return part->reason;
 377                 }
 378         }
 379
 380         return xpc_mark_partition_active(part);
 381 }
 382
 383
 384 /*
 385  * The first kthread assigned to a newly activated partition is the one
 386  * created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
 387  * that kthread until the partition is brought down, at which time that kthread
 388  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
 389  * that XPC has dismantled all communication infrastructure for the associated
 390  * partition.) This kthread becomes the channel manager for that partition.
 391  *
 392  * Each active partition has a channel manager, who, besides connecting and
 393  * disconnecting channels, will ensure that each of the partition's connected
 394  * channels has the required number of assigned kthreads to get the work done.
 395  */
 396 static void
 397 xpc_channel_mgr(struct xpc_partition *part)
 398 {
 399         while (part->act_state != XPC_P_DEACTIVATING ||
 400                         atomic_read(&part->nchannels_active) > 0 ||
 401                                         !xpc_partition_disengaged(part)) {
 402
 403                 xpc_process_channel_activity(part);
 404
 405
 406                 /*
 407                  * Wait until we've been requested to activate kthreads or
 408                  * all of the channel's message queues have been torn down or
 409                  * a signal is pending.
 410                  *
 411                  * The channel_mgr_requests is set to 1 after being awakened,
 412                  * This is done to prevent the channel mgr from making one pass
 413                  * through the loop for each request, since he will
 414                  * be servicing all the requests in one pass. The reason it's
 415                  * set to 1 instead of 0 is so that other kthreads will know
 416                  * that the channel mgr is running and won't bother trying to
 417                  * wake him up.
 418                  */
 419                 atomic_dec(&part->channel_mgr_requests);
 420                 (void) wait_event_interruptible(part->channel_mgr_wq,
 421                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
 422                                 (volatile u64) part->local_IPI_amo != 0 ||
 423                                 ((volatile u8) part->act_state ==
 424                                                         XPC_P_DEACTIVATING &&
 425                                 atomic_read(&part->nchannels_active) == 0 &&
 426                                 xpc_partition_disengaged(part))));
 427                 atomic_set(&part->channel_mgr_requests, 1);
 428
 429                 // >>> Does it need to wakeup periodically as well? In case we
 430                 // >>> miscalculated the #of kthreads to wakeup or create?
 431         }
 432 }
 433
 434
 435 /*
 436  * When XPC HB determines that a partition has come up, it will create a new
 437  * kthread and that kthread will call this function to attempt to set up the
 438  * basic infrastructure used for Cross Partition Communication with the newly
 439  * upped partition.
 440  *
 441  * The kthread that was created by XPC HB and which setup the XPC
 442  * infrastructure will remain assigned to the partition until the partition
 443  * goes down. At which time the kthread will teardown the XPC infrastructure
 444  * and then exit.
 445  *
 446  * XPC HB will put the remote partition's XPC per partition specific variables
 447  * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
 448  * calling xpc_partition_up().
 449  */
 450 static void
 451 xpc_partition_up(struct xpc_partition *part)
 452 {
 453         DBUG_ON(part->channels != NULL);
 454
 455         dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
 456
 457         if (xpc_setup_infrastructure(part) != xpcSuccess) {
 458                 return;
 459         }
 460
 461         /*
 462          * The kthread that XPC HB called us with will become the
 463          * channel manager for this partition. It will not return
 464          * back to XPC HB until the partition's XPC infrastructure
 465          * has been dismantled.
 466          */
 467
 468         (void) xpc_part_ref(part);      /* this will always succeed */
 469
 470         if (xpc_make_first_contact(part) == xpcSuccess) {
 471                 xpc_channel_mgr(part);
 472         }
 473
 474         xpc_part_deref(part);
 475
 476         xpc_teardown_infrastructure(part);
 477 }
 478
 479
 480 static int
 481 xpc_activating(void *__partid)
 482 {
 483         partid_t partid = (u64) __partid;
 484         struct xpc_partition *part = &xpc_partitions[partid];
 485         unsigned long irq_flags;
 486         struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 487         int ret;
 488
 489
 490         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 491
 492         spin_lock_irqsave(&part->act_lock, irq_flags);
 493
 494         if (part->act_state == XPC_P_DEACTIVATING) {
 495                 part->act_state = XPC_P_INACTIVE;
 496                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 497                 part->remote_rp_pa = 0;
 498                 return 0;
 499         }
 500
 501         /* indicate the thread is activating */
 502         DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
 503         part->act_state = XPC_P_ACTIVATING;
 504
 505         XPC_SET_REASON(part, 0, 0);
 506         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 507
 508         dev_dbg(xpc_part, "bringing partition %d up\n", partid);
 509
 510         daemonize("xpc%02d", partid);
 511
 512         /*
 513          * This thread needs to run at a realtime priority to prevent a
 514          * significant performance degradation.
 515          */
 516         ret = sched_setscheduler(current, SCHED_FIFO, &param);
 517         if (ret != 0) {
 518                 dev_warn(xpc_part, "unable to set pid %d to a realtime "
 519                         "priority, ret=%d\n", current->pid, ret);
 520         }
 521
 522         /* allow this thread and its children to run on any CPU */
 523         set_cpus_allowed(current, CPU_MASK_ALL);
 524
 525         /*
 526          * Register the remote partition's AMOs with SAL so it can handle
 527          * and cleanup errors within that address range should the remote
 528          * partition go down. We don't unregister this range because it is
 529          * difficult to tell when outstanding writes to the remote partition
 530          * are finished and thus when it is safe to unregister. This should
 531          * not result in wasted space in the SAL xp_addr_region table because
 532          * we should get the same page for remote_amos_page_pa after module
 533          * reloads and system reboots.
 534          */
 535         if (sn_register_xp_addr_region(part->remote_amos_page_pa,
 536                                                         PAGE_SIZE, 1) < 0) {
 537                 dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
 538                         "xp_addr region\n", partid);
 539
 540                 spin_lock_irqsave(&part->act_lock, irq_flags);
 541                 part->act_state = XPC_P_INACTIVE;
 542                 XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
 543                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 544                 part->remote_rp_pa = 0;
 545                 return 0;
 546         }
 547
 548         xpc_allow_hb(partid, xpc_vars);
 549         xpc_IPI_send_activated(part);
 550
 551
 552         /*
 553          * xpc_partition_up() holds this thread and marks this partition as
 554          * XPC_P_ACTIVE by calling xpc_hb_mark_active().
 555          */
 556         (void) xpc_partition_up(part);
 557
 558         xpc_disallow_hb(partid, xpc_vars);
 559         xpc_mark_partition_inactive(part);
 560
 561         if (part->reason == xpcReactivating) {
 562                 /* interrupting ourselves results in activating partition */
 563                 xpc_IPI_send_reactivate(part);
 564         }
 565
 566         return 0;
 567 }
 568
 569
 570 void
 571 xpc_activate_partition(struct xpc_partition *part)
 572 {
 573         partid_t partid = XPC_PARTID(part);
 574         unsigned long irq_flags;
 575         pid_t pid;
 576
 577
 578         spin_lock_irqsave(&part->act_lock, irq_flags);
 579
 580         DBUG_ON(part->act_state != XPC_P_INACTIVE);
 581
 582         part->act_state = XPC_P_ACTIVATION_REQ;
 583         XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
 584
 585         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 586
 587         pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
 588
 589         if (unlikely(pid <= 0)) {
 590                 spin_lock_irqsave(&part->act_lock, irq_flags);
 591                 part->act_state = XPC_P_INACTIVE;
 592                 XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
 593                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 594         }
 595 }
 596
 597
 598 /*
 599  * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
 600  * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
 601  * than one partition, we use an AMO_t structure per partition to indicate
 602  * whether a partition has sent an IPI or not.  >>> If it has, then wake up the
 603  * associated kthread to handle it.
 604  *
 605  * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
 606  * running on other partitions.
 607  *
 608  * Noteworthy Arguments:
 609  *
 610  *      irq - Interrupt ReQuest number. NOT USED.
 611  *
 612  *      dev_id - partid of IPI's potential sender.
 613  */
 614 irqreturn_t
 615 xpc_notify_IRQ_handler(int irq, void *dev_id)
 616 {
 617         partid_t partid = (partid_t) (u64) dev_id;
 618         struct xpc_partition *part = &xpc_partitions[partid];
 619
 620
 621         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 622
 623         if (xpc_part_ref(part)) {
 624                 xpc_check_for_channel_activity(part);
 625
 626                 xpc_part_deref(part);
 627         }
 628         return IRQ_HANDLED;
 629 }
 630
 631
 632 /*
 633  * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
 634  * because the write to their associated IPI amo completed after the IRQ/IPI
 635  * was received.
 636  */
 637 void
 638 xpc_dropped_IPI_check(struct xpc_partition *part)
 639 {
 640         if (xpc_part_ref(part)) {
 641                 xpc_check_for_channel_activity(part);
 642
 643                 part->dropped_IPI_timer.expires = jiffies +
 644                                                         XPC_P_DROPPED_IPI_WAIT;
 645                 add_timer(&part->dropped_IPI_timer);
 646                 xpc_part_deref(part);
 647         }
 648 }
 649
 650
 651 void
 652 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
 653 {
 654         int idle = atomic_read(&ch->kthreads_idle);
 655         int assigned = atomic_read(&ch->kthreads_assigned);
 656         int wakeup;
 657
 658
 659         DBUG_ON(needed <= 0);
 660
 661         if (idle > 0) {
 662                 wakeup = (needed > idle) ? idle : needed;
 663                 needed -= wakeup;
 664
 665                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
 666                         "channel=%d\n", wakeup, ch->partid, ch->number);
 667
 668                 /* only wakeup the requested number of kthreads */
 669                 wake_up_nr(&ch->idle_wq, wakeup);
 670         }
 671
 672         if (needed <= 0) {
 673                 return;
 674         }
 675
 676         if (needed + assigned > ch->kthreads_assigned_limit) {
 677                 needed = ch->kthreads_assigned_limit - assigned;
 678                 // >>>should never be less than 0
 679                 if (needed <= 0) {
 680                         return;
 681                 }
 682         }
 683
 684         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
 685                 needed, ch->partid, ch->number);
 686
 687         xpc_create_kthreads(ch, needed, 0);
 688 }
 689
 690
 691 /*
 692  * This function is where XPC's kthreads wait for messages to deliver.
 693  */
 694 static void
 695 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
 696 {
 697         do {
 698                 /* deliver messages to their intended recipients */
 699
 700                 while ((volatile s64) ch->w_local_GP.get <
 701                                 (volatile s64) ch->w_remote_GP.put &&
 702                                         !((volatile u32) ch->flags &
 703                                                 XPC_C_DISCONNECTING)) {
 704                         xpc_deliver_msg(ch);
 705                 }
 706
 707                 if (atomic_inc_return(&ch->kthreads_idle) >
 708                                                 ch->kthreads_idle_limit) {
 709                         /* too many idle kthreads on this channel */
 710                         atomic_dec(&ch->kthreads_idle);
 711                         break;
 712                 }
 713
 714                 dev_dbg(xpc_chan, "idle kthread calling "
 715                         "wait_event_interruptible_exclusive()\n");
 716
 717                 (void) wait_event_interruptible_exclusive(ch->idle_wq,
 718                                 ((volatile s64) ch->w_local_GP.get <
 719                                         (volatile s64) ch->w_remote_GP.put ||
 720                                 ((volatile u32) ch->flags &
 721                                                 XPC_C_DISCONNECTING)));
 722
 723                 atomic_dec(&ch->kthreads_idle);
 724
 725         } while (!((volatile u32) ch->flags & XPC_C_DISCONNECTING));
 726 }
 727
 728
 729 static int
 730 xpc_daemonize_kthread(void *args)
 731 {
 732         partid_t partid = XPC_UNPACK_ARG1(args);
 733         u16 ch_number = XPC_UNPACK_ARG2(args);
 734         struct xpc_partition *part = &xpc_partitions[partid];
 735         struct xpc_channel *ch;
 736         int n_needed;
 737         unsigned long irq_flags;
 738
 739
 740         daemonize("xpc%02dc%d", partid, ch_number);
 741
 742         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
 743                 partid, ch_number);
 744
 745         ch = &part->channels[ch_number];
 746
 747         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 748
 749                 /* let registerer know that connection has been established */
 750
 751                 spin_lock_irqsave(&ch->lock, irq_flags);
 752                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
 753                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
 754                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 755
 756                         xpc_connected_callout(ch);
 757
 758                         spin_lock_irqsave(&ch->lock, irq_flags);
 759                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
 760                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 761
 762                         /*
 763                          * It is possible that while the callout was being
 764                          * made that the remote partition sent some messages.
 765                          * If that is the case, we may need to activate
 766                          * additional kthreads to help deliver them. We only
 767                          * need one less than total #of messages to deliver.
 768                          */
 769                         n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
 770                         if (n_needed > 0 &&
 771                                         !(ch->flags & XPC_C_DISCONNECTING)) {
 772                                 xpc_activate_kthreads(ch, n_needed);
 773                         }
 774                 } else {
 775                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 776                 }
 777
 778                 xpc_kthread_waitmsgs(part, ch);
 779         }
 780
 781         /* let registerer know that connection is disconnecting */
 782
 783         spin_lock_irqsave(&ch->lock, irq_flags);
 784         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 785                         !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 786                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
 787                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 788
 789                 xpc_disconnect_callout(ch, xpcDisconnecting);
 790
 791                 spin_lock_irqsave(&ch->lock, irq_flags);
 792                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
 793         }
 794         spin_unlock_irqrestore(&ch->lock, irq_flags);
 795
 796         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
 797                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
 798                         xpc_mark_partition_disengaged(part);
 799                         xpc_IPI_send_disengage(part);
 800                 }
 801         }
 802
 803         xpc_msgqueue_deref(ch);
 804
 805         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 806                 partid, ch_number);
 807
 808         xpc_part_deref(part);
 809         return 0;
 810 }
 811
 812
 813 /*
 814  * For each partition that XPC has established communications with, there is
 815  * a minimum of one kernel thread assigned to perform any operation that
 816  * may potentially sleep or block (basically the callouts to the asynchronous
 817  * functions registered via xpc_connect()).
 818  *
 819  * Additional kthreads are created and destroyed by XPC as the workload
 820  * demands.
 821  *
 822  * A kthread is assigned to one of the active channels that exists for a given
 823  * partition.
 824  */
 825 void
 826 xpc_create_kthreads(struct xpc_channel *ch, int needed,
 827                         int ignore_disconnecting)
 828 {
 829         unsigned long irq_flags;
 830         pid_t pid;
 831         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
 832         struct xpc_partition *part = &xpc_partitions[ch->partid];
 833
 834
 835         while (needed-- > 0) {
 836
 837                 /*
 838                  * The following is done on behalf of the newly created
 839                  * kthread. That kthread is responsible for doing the
 840                  * counterpart to the following before it exits.
 841                  */
 842                 if (ignore_disconnecting) {
 843                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
 844                                 /* kthreads assigned had gone to zero */
 845                                 BUG_ON(!(ch->flags &
 846                                         XPC_C_DISCONNECTINGCALLOUT_MADE));
 847                                 break;
 848                         }
 849
 850                 } else if (ch->flags & XPC_C_DISCONNECTING) {
 851                         break;
 852
 853                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1) {
 854                         if (atomic_inc_return(&part->nchannels_engaged) == 1)
 855                                 xpc_mark_partition_engaged(part);
 856                 }
 857                 (void) xpc_part_ref(part);
 858                 xpc_msgqueue_ref(ch);
 859
 860                 pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
 861                 if (pid < 0) {
 862                         /* the fork failed */
 863
 864                         /*
 865                          * NOTE: if (ignore_disconnecting &&
 866                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
 867                          * then we'll deadlock if all other kthreads assigned
 868                          * to this channel are blocked in the channel's
 869                          * registerer, because the only thing that will unblock
 870                          * them is the xpcDisconnecting callout that this
 871                          * failed kernel_thread would have made.
 872                          */
 873
 874                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 875                             atomic_dec_return(&part->nchannels_engaged) == 0) {
 876                                 xpc_mark_partition_disengaged(part);
 877                                 xpc_IPI_send_disengage(part);
 878                         }
 879                         xpc_msgqueue_deref(ch);
 880                         xpc_part_deref(part);
 881
 882                         if (atomic_read(&ch->kthreads_assigned) <
 883                                                 ch->kthreads_idle_limit) {
 884                                 /*
 885                                  * Flag this as an error only if we have an
 886                                  * insufficient #of kthreads for the channel
 887                                  * to function.
 888                                  */
 889                                 spin_lock_irqsave(&ch->lock, irq_flags);
 890                                 XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
 891                                                                 &irq_flags);
 892                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 893                         }
 894                         break;
 895                 }
 896
 897                 ch->kthreads_created++; // >>> temporary debug only!!!
 898         }
 899 }
 900
 901
 902 void
 903 xpc_disconnect_wait(int ch_number)
 904 {
 905         unsigned long irq_flags;
 906         partid_t partid;
 907         struct xpc_partition *part;
 908         struct xpc_channel *ch;
 909         int wakeup_channel_mgr;
 910
 911
 912         /* now wait for all callouts to the caller's function to cease */
 913         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 914                 part = &xpc_partitions[partid];
 915
 916                 if (!xpc_part_ref(part)) {
 917                         continue;
 918                 }
 919
 920                 ch = &part->channels[ch_number];
 921
 922                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
 923                         xpc_part_deref(part);
 924                         continue;
 925                 }
 926
 927                 wait_for_completion(&ch->wdisconnect_wait);
 928
 929                 spin_lock_irqsave(&ch->lock, irq_flags);
 930                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 931                 wakeup_channel_mgr = 0;
 932
 933                 if (ch->delayed_IPI_flags) {
 934                         if (part->act_state != XPC_P_DEACTIVATING) {
 935                                 spin_lock(&part->IPI_lock);
 936                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 937                                         ch->number, ch->delayed_IPI_flags);
 938                                 spin_unlock(&part->IPI_lock);
 939                                 wakeup_channel_mgr = 1;
 940                         }
 941                         ch->delayed_IPI_flags = 0;
 942                 }
 943
 944                 ch->flags &= ~XPC_C_WDISCONNECT;
 945                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 946
 947                 if (wakeup_channel_mgr) {
 948                         xpc_wakeup_channel_mgr(part);
 949                 }
 950
 951                 xpc_part_deref(part);
 952         }
 953 }
 954
 955
 956 static void
 957 xpc_do_exit(enum xpc_retval reason)
 958 {
 959         partid_t partid;
 960         int active_part_count, printed_waiting_msg = 0;
 961         struct xpc_partition *part;
 962         unsigned long printmsg_time, disengage_request_timeout = 0;
 963
 964
 965         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 966         DBUG_ON(xpc_exiting == 1);
 967
 968         /*
 969          * Let the heartbeat checker thread and the discovery thread
 970          * (if one is running) know that they should exit. Also wake up
 971          * the heartbeat checker thread in case it's sleeping.
 972          */
 973         xpc_exiting = 1;
 974         wake_up_interruptible(&xpc_act_IRQ_wq);
 975
 976         /* ignore all incoming interrupts */
 977         free_irq(SGI_XPC_ACTIVATE, NULL);
 978
 979         /* wait for the discovery thread to exit */
 980         wait_for_completion(&xpc_discovery_exited);
 981
 982         /* wait for the heartbeat checker thread to exit */
 983         wait_for_completion(&xpc_hb_checker_exited);
 984
 985
 986         /* sleep for a 1/3 of a second or so */
 987         (void) msleep_interruptible(300);
 988
 989
 990         /* wait for all partitions to become inactive */
 991
 992         printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 993         xpc_disengage_request_timedout = 0;
 994
 995         do {
 996                 active_part_count = 0;
 997
 998                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 999                         part = &xpc_partitions[partid];
1000
1001                         if (xpc_partition_disengaged(part) &&
1002                                         part->act_state == XPC_P_INACTIVE) {
1003                                 continue;
1004                         }
1005
1006                         active_part_count++;
1007
1008                         XPC_DEACTIVATE_PARTITION(part, reason);
1009
1010                         if (part->disengage_request_timeout >
1011                                                 disengage_request_timeout) {
1012                                 disengage_request_timeout =
1013                                                 part->disengage_request_timeout;
1014                         }
1015                 }
1016
1017                 if (xpc_partition_engaged(-1UL)) {
1018                         if (time_after(jiffies, printmsg_time)) {
1019                                 dev_info(xpc_part, "waiting for remote "
1020                                         "partitions to disengage, timeout in "
1021                                         "%ld seconds\n",
1022                                         (disengage_request_timeout - jiffies)
1023                                                                         / HZ);
1024                                 printmsg_time = jiffies +
1025                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
1026                                 printed_waiting_msg = 1;
1027                         }
1028
1029                 } else if (active_part_count > 0) {
1030                         if (printed_waiting_msg) {
1031                                 dev_info(xpc_part, "waiting for local partition"
1032                                         " to disengage\n");
1033                                 printed_waiting_msg = 0;
1034                         }
1035
1036                 } else {
1037                         if (!xpc_disengage_request_timedout) {
1038                                 dev_info(xpc_part, "all partitions have "
1039                                         "disengaged\n");
1040                         }
1041                         break;
1042                 }
1043
1044                 /* sleep for a 1/3 of a second or so */
1045                 (void) msleep_interruptible(300);
1046
1047         } while (1);
1048
1049         DBUG_ON(xpc_partition_engaged(-1UL));
1050
1051
1052         /* indicate to others that our reserved page is uninitialized */
1053         xpc_rsvd_page->vars_pa = 0;
1054
1055         /* now it's time to eliminate our heartbeat */
1056         del_timer_sync(&xpc_hb_timer);
1057         DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
1058
1059         if (reason == xpcUnloading) {
1060                 /* take ourselves off of the reboot_notifier_list */
1061                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1062
1063                 /* take ourselves off of the die_notifier list */
1064                 (void) unregister_die_notifier(&xpc_die_notifier);
1065         }
1066
1067         /* close down protections for IPI operations */
1068         xpc_restrict_IPI_ops();
1069
1070
1071         /* clear the interface to XPC's functions */
1072         xpc_clear_interface();
1073
1074         if (xpc_sysctl) {
1075                 unregister_sysctl_table(xpc_sysctl);
1076         }
1077
1078         kfree(xpc_remote_copy_buffer_base);
1079 }
1080
1081
1082 /*
1083  * This function is called when the system is being rebooted.
1084  */
1085 static int
1086 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1087 {
1088         enum xpc_retval reason;
1089
1090
1091         switch (event) {
1092         case SYS_RESTART:
1093                 reason = xpcSystemReboot;
1094                 break;
1095         case SYS_HALT:
1096                 reason = xpcSystemHalt;
1097                 break;
1098         case SYS_POWER_OFF:
1099                 reason = xpcSystemPoweroff;
1100                 break;
1101         default:
1102                 reason = xpcSystemGoingDown;
1103         }
1104
1105         xpc_do_exit(reason);
1106         return NOTIFY_DONE;
1107 }
1108
1109
1110 /*
1111  * Notify other partitions to disengage from all references to our memory.
1112  */
1113 static void
1114 xpc_die_disengage(void)
1115 {
1116         struct xpc_partition *part;
1117         partid_t partid;
1118         unsigned long engaged;
1119         long time, printmsg_time, disengage_request_timeout;
1120
1121
1122         /* keep xpc_hb_checker thread from doing anything (just in case) */
1123         xpc_exiting = 1;
1124
1125         xpc_vars->heartbeating_to_mask = 0;  /* indicate we're deactivated */
1126
1127         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1128                 part = &xpc_partitions[partid];
1129
1130                 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
1131                                                         remote_vars_version)) {
1132
1133                         /* just in case it was left set by an earlier XPC */
1134                         xpc_clear_partition_engaged(1UL << partid);
1135                         continue;
1136                 }
1137
1138                 if (xpc_partition_engaged(1UL << partid) ||
1139                                         part->act_state != XPC_P_INACTIVE) {
1140                         xpc_request_partition_disengage(part);
1141                         xpc_mark_partition_disengaged(part);
1142                         xpc_IPI_send_disengage(part);
1143                 }
1144         }
1145
1146         time = rtc_time();
1147         printmsg_time = time +
1148                 (XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
1149         disengage_request_timeout = time +
1150                 (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1151
1152         /* wait for all other partitions to disengage from us */
1153
1154         while (1) {
1155                 engaged = xpc_partition_engaged(-1UL);
1156                 if (!engaged) {
1157                         dev_info(xpc_part, "all partitions have disengaged\n");
1158                         break;
1159                 }
1160
1161                 time = rtc_time();
1162                 if (time >= disengage_request_timeout) {
1163                         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1164                                 if (engaged & (1UL << partid)) {
1165                                         dev_info(xpc_part, "disengage from "
1166                                                 "remote partition %d timed "
1167                                                 "out\n", partid);
1168                                 }
1169                         }
1170                         break;
1171                 }
1172
1173                 if (time >= printmsg_time) {
1174                         dev_info(xpc_part, "waiting for remote partitions to "
1175                                 "disengage, timeout in %ld seconds\n",
1176                                 (disengage_request_timeout - time) /
1177                                                 sn_rtc_cycles_per_second);
1178                         printmsg_time = time +
1179                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1180                                                 sn_rtc_cycles_per_second);
1181                 }
1182         }
1183 }
1184
1185
1186 /*
1187  * This function is called when the system is being restarted or halted due
1188  * to some sort of system failure. If this is the case we need to notify the
1189  * other partitions to disengage from all references to our memory.
1190  * This function can also be called when our heartbeater could be offlined
1191  * for a time. In this case we need to notify other partitions to not worry
1192  * about the lack of a heartbeat.
1193  */
1194 static int
1195 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1196 {
1197         switch (event) {
1198         case DIE_MACHINE_RESTART:
1199         case DIE_MACHINE_HALT:
1200                 xpc_die_disengage();
1201                 break;
1202
1203         case DIE_KDEBUG_ENTER:
1204                 /* Should lack of heartbeat be ignored by other partitions? */
1205                 if (!xpc_kdebug_ignore) {
1206                         break;
1207                 }
1208                 /* fall through */
1209         case DIE_MCA_MONARCH_ENTER:
1210         case DIE_INIT_MONARCH_ENTER:
1211                 xpc_vars->heartbeat++;
1212                 xpc_vars->heartbeat_offline = 1;
1213                 break;
1214
1215         case DIE_KDEBUG_LEAVE:
1216                 /* Is lack of heartbeat being ignored by other partitions? */
1217                 if (!xpc_kdebug_ignore) {
1218                         break;
1219                 }
1220                 /* fall through */
1221         case DIE_MCA_MONARCH_LEAVE:
1222         case DIE_INIT_MONARCH_LEAVE:
1223                 xpc_vars->heartbeat++;
1224                 xpc_vars->heartbeat_offline = 0;
1225                 break;
1226         }
1227
1228         return NOTIFY_DONE;
1229 }
1230
1231
1232 int __init
1233 xpc_init(void)
1234 {
1235         int ret;
1236         partid_t partid;
1237         struct xpc_partition *part;
1238         pid_t pid;
1239         size_t buf_size;
1240
1241
1242         if (!ia64_platform_is("sn2")) {
1243                 return -ENODEV;
1244         }
1245
1246
1247         buf_size = max(XPC_RP_VARS_SIZE,
1248                                 XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES);
1249         xpc_remote_copy_buffer = xpc_kmalloc_cacheline_aligned(buf_size,
1250                                      GFP_KERNEL, &xpc_remote_copy_buffer_base);
1251         if (xpc_remote_copy_buffer == NULL)
1252                 return -ENOMEM;
1253
1254         snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1255         snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1256
1257         xpc_sysctl = register_sysctl_table(xpc_sys_dir, 1);
1258
1259         /*
1260          * The first few fields of each entry of xpc_partitions[] need to
1261          * be initialized now so that calls to xpc_connect() and
1262          * xpc_disconnect() can be made prior to the activation of any remote
1263          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1264          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1265          * PARTITION HAS BEEN ACTIVATED.
1266          */
1267         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1268                 part = &xpc_partitions[partid];
1269
1270                 DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
1271
1272                 part->act_IRQ_rcvd = 0;
1273                 spin_lock_init(&part->act_lock);
1274                 part->act_state = XPC_P_INACTIVE;
1275                 XPC_SET_REASON(part, 0, 0);
1276
1277                 init_timer(&part->disengage_request_timer);
1278                 part->disengage_request_timer.function =
1279                                 xpc_timeout_partition_disengage_request;
1280                 part->disengage_request_timer.data = (unsigned long) part;
1281
1282                 part->setup_state = XPC_P_UNSET;
1283                 init_waitqueue_head(&part->teardown_wq);
1284                 atomic_set(&part->references, 0);
1285         }
1286
1287         /*
1288          * Open up protections for IPI operations (and AMO operations on
1289          * Shub 1.1 systems).
1290          */
1291         xpc_allow_IPI_ops();
1292
1293         /*
1294          * Interrupts being processed will increment this atomic variable and
1295          * awaken the heartbeat thread which will process the interrupts.
1296          */
1297         atomic_set(&xpc_act_IRQ_rcvd, 0);
1298
1299         /*
1300          * This is safe to do before the xpc_hb_checker thread has started
1301          * because the handler releases a wait queue.  If an interrupt is
1302          * received before the thread is waiting, it will not go to sleep,
1303          * but rather immediately process the interrupt.
1304          */
1305         ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1306                                                         "xpc hb", NULL);
1307         if (ret != 0) {
1308                 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1309                         "errno=%d\n", -ret);
1310
1311                 xpc_restrict_IPI_ops();
1312
1313                 if (xpc_sysctl) {
1314                         unregister_sysctl_table(xpc_sysctl);
1315                 }
1316
1317                 kfree(xpc_remote_copy_buffer_base);
1318                 return -EBUSY;
1319         }
1320
1321         /*
1322          * Fill the partition reserved page with the information needed by
1323          * other partitions to discover we are alive and establish initial
1324          * communications.
1325          */
1326         xpc_rsvd_page = xpc_rsvd_page_init();
1327         if (xpc_rsvd_page == NULL) {
1328                 dev_err(xpc_part, "could not setup our reserved page\n");
1329
1330                 free_irq(SGI_XPC_ACTIVATE, NULL);
1331                 xpc_restrict_IPI_ops();
1332
1333                 if (xpc_sysctl) {
1334                         unregister_sysctl_table(xpc_sysctl);
1335                 }
1336
1337                 kfree(xpc_remote_copy_buffer_base);
1338                 return -EBUSY;
1339         }
1340
1341
1342         /* add ourselves to the reboot_notifier_list */
1343         ret = register_reboot_notifier(&xpc_reboot_notifier);
1344         if (ret != 0) {
1345                 dev_warn(xpc_part, "can't register reboot notifier\n");
1346         }
1347
1348         /* add ourselves to the die_notifier list (i.e., ia64die_chain) */
1349         ret = register_die_notifier(&xpc_die_notifier);
1350         if (ret != 0) {
1351                 dev_warn(xpc_part, "can't register die notifier\n");
1352         }
1353
1354
1355         /*
1356          * Set the beating to other partitions into motion.  This is
1357          * the last requirement for other partitions' discovery to
1358          * initiate communications with us.
1359          */
1360         init_timer(&xpc_hb_timer);
1361         xpc_hb_timer.function = xpc_hb_beater;
1362         xpc_hb_beater(0);
1363
1364
1365         /*
1366          * The real work-horse behind xpc.  This processes incoming
1367          * interrupts and monitors remote heartbeats.
1368          */
1369         pid = kernel_thread(xpc_hb_checker, NULL, 0);
1370         if (pid < 0) {
1371                 dev_err(xpc_part, "failed while forking hb check thread\n");
1372
1373                 /* indicate to others that our reserved page is uninitialized */
1374                 xpc_rsvd_page->vars_pa = 0;
1375
1376                 /* take ourselves off of the reboot_notifier_list */
1377                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1378
1379                 /* take ourselves off of the die_notifier list */
1380                 (void) unregister_die_notifier(&xpc_die_notifier);
1381
1382                 del_timer_sync(&xpc_hb_timer);
1383                 free_irq(SGI_XPC_ACTIVATE, NULL);
1384                 xpc_restrict_IPI_ops();
1385
1386                 if (xpc_sysctl) {
1387                         unregister_sysctl_table(xpc_sysctl);
1388                 }
1389
1390                 kfree(xpc_remote_copy_buffer_base);
1391                 return -EBUSY;
1392         }
1393
1394
1395         /*
1396          * Startup a thread that will attempt to discover other partitions to
1397          * activate based on info provided by SAL. This new thread is short
1398          * lived and will exit once discovery is complete.
1399          */
1400         pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
1401         if (pid < 0) {
1402                 dev_err(xpc_part, "failed while forking discovery thread\n");
1403
1404                 /* mark this new thread as a non-starter */
1405                 complete(&xpc_discovery_exited);
1406
1407                 xpc_do_exit(xpcUnloading);
1408                 return -EBUSY;
1409         }
1410
1411
1412         /* set the interface to point at XPC's functions */
1413         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1414                           xpc_initiate_allocate, xpc_initiate_send,
1415                           xpc_initiate_send_notify, xpc_initiate_received,
1416                           xpc_initiate_partid_to_nasids);
1417
1418         return 0;
1419 }
1420 module_init(xpc_init);
1421
1422
1423 void __exit
1424 xpc_exit(void)
1425 {
1426         xpc_do_exit(xpcUnloading);
1427 }
1428 module_exit(xpc_exit);
1429
1430
1431 MODULE_AUTHOR("Silicon Graphics, Inc.");
1432 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1433 MODULE_LICENSE("GPL");
1434
1435 module_param(xpc_hb_interval, int, 0);
1436 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1437                 "heartbeat increments.");
1438
1439 module_param(xpc_hb_check_interval, int, 0);
1440 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1441                 "heartbeat checks.");
1442
1443 module_param(xpc_disengage_request_timelimit, int, 0);
1444 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1445                 "for disengage request to complete.");
1446
1447 module_param(xpc_kdebug_ignore, int, 0);
1448 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1449                 "other partitions when dropping into kdebug.");
1450