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 <linux/kdebug.h>
  59 #include <asm/sn/intr.h>
  60 #include <asm/sn/sn_sal.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 static int xpc_kdebug_entered;
  87
  88
  89 /* systune related variables for /proc/sys directories */
  90
  91 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
  92 static int xpc_hb_min_interval = 1;
  93 static int xpc_hb_max_interval = 10;
  94
  95 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
  96 static int xpc_hb_check_min_interval = 10;
  97 static int xpc_hb_check_max_interval = 120;
  98
  99 int xpc_disengage_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
 100 static int xpc_disengage_request_min_timelimit = 0;
 101 static int xpc_disengage_request_max_timelimit = 120;
 102
 103 static ctl_table xpc_sys_xpc_hb_dir[] = {
 104         {
 105                 .ctl_name       = CTL_UNNUMBERED,
 106                 .procname       = "hb_interval",
 107                 .data           = &xpc_hb_interval,
 108                 .maxlen         = sizeof(int),
 109                 .mode           = 0644,
 110                 .proc_handler   = &proc_dointvec_minmax,
 111                 .strategy       = &sysctl_intvec,
 112                 .extra1         = &xpc_hb_min_interval,
 113                 .extra2         = &xpc_hb_max_interval
 114         },
 115         {
 116                 .ctl_name       = CTL_UNNUMBERED,
 117                 .procname       = "hb_check_interval",
 118                 .data           = &xpc_hb_check_interval,
 119                 .maxlen         = sizeof(int),
 120                 .mode           = 0644,
 121                 .proc_handler   = &proc_dointvec_minmax,
 122                 .strategy       = &sysctl_intvec,
 123                 .extra1         = &xpc_hb_check_min_interval,
 124                 .extra2         = &xpc_hb_check_max_interval
 125         },
 126         {}
 127 };
 128 static ctl_table xpc_sys_xpc_dir[] = {
 129         {
 130                 .ctl_name       = CTL_UNNUMBERED,
 131                 .procname       = "hb",
 132                 .mode           = 0555,
 133                 .child          = xpc_sys_xpc_hb_dir
 134         },
 135         {
 136                 .ctl_name       = CTL_UNNUMBERED,
 137                 .procname       = "disengage_request_timelimit",
 138                 .data           = &xpc_disengage_request_timelimit,
 139                 .maxlen         = sizeof(int),
 140                 .mode           = 0644,
 141                 .proc_handler   = &proc_dointvec_minmax,
 142                 .strategy       = &sysctl_intvec,
 143                 .extra1         = &xpc_disengage_request_min_timelimit,
 144                 .extra2         = &xpc_disengage_request_max_timelimit
 145         },
 146         {}
 147 };
 148 static ctl_table xpc_sys_dir[] = {
 149         {
 150                 .ctl_name       = CTL_UNNUMBERED,
 151                 .procname       = "xpc",
 152                 .mode           = 0555,
 153                 .child          = xpc_sys_xpc_dir
 154         },
 155         {}
 156 };
 157 static struct ctl_table_header *xpc_sysctl;
 158
 159 /* non-zero if any remote partition disengage request was timed out */
 160 int xpc_disengage_request_timedout;
 161
 162 /* #of IRQs received */
 163 static atomic_t xpc_act_IRQ_rcvd;
 164
 165 /* IRQ handler notifies this wait queue on receipt of an IRQ */
 166 static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
 167
 168 static unsigned long xpc_hb_check_timeout;
 169
 170 /* notification that the xpc_hb_checker thread has exited */
 171 static DECLARE_COMPLETION(xpc_hb_checker_exited);
 172
 173 /* notification that the xpc_discovery thread has exited */
 174 static DECLARE_COMPLETION(xpc_discovery_exited);
 175
 176
 177 static struct timer_list xpc_hb_timer;
 178
 179
 180 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
 181
 182
 183 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
 184 static struct notifier_block xpc_reboot_notifier = {
 185         .notifier_call = xpc_system_reboot,
 186 };
 187
 188 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
 189 static struct notifier_block xpc_die_notifier = {
 190         .notifier_call = xpc_system_die,
 191 };
 192
 193
 194 /*
 195  * Timer function to enforce the timelimit on the partition disengage request.
 196  */
 197 static void
 198 xpc_timeout_partition_disengage_request(unsigned long data)
 199 {
 200         struct xpc_partition *part = (struct xpc_partition *) data;
 201
 202
 203         DBUG_ON(jiffies < part->disengage_request_timeout);
 204
 205         (void) xpc_partition_disengaged(part);
 206
 207         DBUG_ON(part->disengage_request_timeout != 0);
 208         DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
 209 }
 210
 211
 212 /*
 213  * Notify the heartbeat check thread that an IRQ has been received.
 214  */
 215 static irqreturn_t
 216 xpc_act_IRQ_handler(int irq, void *dev_id)
 217 {
 218         atomic_inc(&xpc_act_IRQ_rcvd);
 219         wake_up_interruptible(&xpc_act_IRQ_wq);
 220         return IRQ_HANDLED;
 221 }
 222
 223
 224 /*
 225  * Timer to produce the heartbeat.  The timer structures function is
 226  * already set when this is initially called.  A tunable is used to
 227  * specify when the next timeout should occur.
 228  */
 229 static void
 230 xpc_hb_beater(unsigned long dummy)
 231 {
 232         xpc_vars->heartbeat++;
 233
 234         if (jiffies >= xpc_hb_check_timeout) {
 235                 wake_up_interruptible(&xpc_act_IRQ_wq);
 236         }
 237
 238         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
 239         add_timer(&xpc_hb_timer);
 240 }
 241
 242
 243 /*
 244  * This thread is responsible for nearly all of the partition
 245  * activation/deactivation.
 246  */
 247 static int
 248 xpc_hb_checker(void *ignore)
 249 {
 250         int last_IRQ_count = 0;
 251         int new_IRQ_count;
 252         int force_IRQ=0;
 253
 254
 255         /* this thread was marked active by xpc_hb_init() */
 256
 257         daemonize(XPC_HB_CHECK_THREAD_NAME);
 258
 259         set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
 260
 261         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
 262
 263         while (!(volatile int) xpc_exiting) {
 264
 265                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
 266                         "been received\n",
 267                         (int) (xpc_hb_check_timeout - jiffies),
 268                         atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
 269
 270
 271                 /* checking of remote heartbeats is skewed by IRQ handling */
 272                 if (jiffies >= xpc_hb_check_timeout) {
 273                         dev_dbg(xpc_part, "checking remote heartbeats\n");
 274                         xpc_check_remote_hb();
 275
 276                         /*
 277                          * We need to periodically recheck to ensure no
 278                          * IPI/AMO pairs have been missed.  That check
 279                          * must always reset xpc_hb_check_timeout.
 280                          */
 281                         force_IRQ = 1;
 282                 }
 283
 284
 285                 /* check for outstanding IRQs */
 286                 new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
 287                 if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
 288                         force_IRQ = 0;
 289
 290                         dev_dbg(xpc_part, "found an IRQ to process; will be "
 291                                 "resetting xpc_hb_check_timeout\n");
 292
 293                         last_IRQ_count += xpc_identify_act_IRQ_sender();
 294                         if (last_IRQ_count < new_IRQ_count) {
 295                                 /* retry once to help avoid missing AMO */
 296                                 (void) xpc_identify_act_IRQ_sender();
 297                         }
 298                         last_IRQ_count = new_IRQ_count;
 299
 300                         xpc_hb_check_timeout = jiffies +
 301                                            (xpc_hb_check_interval * HZ);
 302                 }
 303
 304                 /* wait for IRQ or timeout */
 305                 (void) wait_event_interruptible(xpc_act_IRQ_wq,
 306                             (last_IRQ_count < atomic_read(&xpc_act_IRQ_rcvd) ||
 307                                         jiffies >= xpc_hb_check_timeout ||
 308                                                 (volatile int) xpc_exiting));
 309         }
 310
 311         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 312
 313
 314         /* mark this thread as having exited */
 315         complete(&xpc_hb_checker_exited);
 316         return 0;
 317 }
 318
 319
 320 /*
 321  * This thread will attempt to discover other partitions to activate
 322  * based on info provided by SAL. This new thread is short lived and
 323  * will exit once discovery is complete.
 324  */
 325 static int
 326 xpc_initiate_discovery(void *ignore)
 327 {
 328         daemonize(XPC_DISCOVERY_THREAD_NAME);
 329
 330         xpc_discovery();
 331
 332         dev_dbg(xpc_part, "discovery thread is exiting\n");
 333
 334         /* mark this thread as having exited */
 335         complete(&xpc_discovery_exited);
 336         return 0;
 337 }
 338
 339
 340 /*
 341  * Establish first contact with the remote partititon. This involves pulling
 342  * the XPC per partition variables from the remote partition and waiting for
 343  * the remote partition to pull ours.
 344  */
 345 static enum xpc_retval
 346 xpc_make_first_contact(struct xpc_partition *part)
 347 {
 348         enum xpc_retval ret;
 349
 350
 351         while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
 352                 if (ret != xpcRetry) {
 353                         XPC_DEACTIVATE_PARTITION(part, ret);
 354                         return ret;
 355                 }
 356
 357                 dev_dbg(xpc_chan, "waiting to make first contact with "
 358                         "partition %d\n", XPC_PARTID(part));
 359
 360                 /* wait a 1/4 of a second or so */
 361                 (void) msleep_interruptible(250);
 362
 363                 if (part->act_state == XPC_P_DEACTIVATING) {
 364                         return part->reason;
 365                 }
 366         }
 367
 368         return xpc_mark_partition_active(part);
 369 }
 370
 371
 372 /*
 373  * The first kthread assigned to a newly activated partition is the one
 374  * created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
 375  * that kthread until the partition is brought down, at which time that kthread
 376  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
 377  * that XPC has dismantled all communication infrastructure for the associated
 378  * partition.) This kthread becomes the channel manager for that partition.
 379  *
 380  * Each active partition has a channel manager, who, besides connecting and
 381  * disconnecting channels, will ensure that each of the partition's connected
 382  * channels has the required number of assigned kthreads to get the work done.
 383  */
 384 static void
 385 xpc_channel_mgr(struct xpc_partition *part)
 386 {
 387         while (part->act_state != XPC_P_DEACTIVATING ||
 388                         atomic_read(&part->nchannels_active) > 0 ||
 389                                         !xpc_partition_disengaged(part)) {
 390
 391                 xpc_process_channel_activity(part);
 392
 393
 394                 /*
 395                  * Wait until we've been requested to activate kthreads or
 396                  * all of the channel's message queues have been torn down or
 397                  * a signal is pending.
 398                  *
 399                  * The channel_mgr_requests is set to 1 after being awakened,
 400                  * This is done to prevent the channel mgr from making one pass
 401                  * through the loop for each request, since he will
 402                  * be servicing all the requests in one pass. The reason it's
 403                  * set to 1 instead of 0 is so that other kthreads will know
 404                  * that the channel mgr is running and won't bother trying to
 405                  * wake him up.
 406                  */
 407                 atomic_dec(&part->channel_mgr_requests);
 408                 (void) wait_event_interruptible(part->channel_mgr_wq,
 409                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
 410                                 (volatile u64) part->local_IPI_amo != 0 ||
 411                                 ((volatile u8) part->act_state ==
 412                                                         XPC_P_DEACTIVATING &&
 413                                 atomic_read(&part->nchannels_active) == 0 &&
 414                                 xpc_partition_disengaged(part))));
 415                 atomic_set(&part->channel_mgr_requests, 1);
 416
 417                 // >>> Does it need to wakeup periodically as well? In case we
 418                 // >>> miscalculated the #of kthreads to wakeup or create?
 419         }
 420 }
 421
 422
 423 /*
 424  * When XPC HB determines that a partition has come up, it will create a new
 425  * kthread and that kthread will call this function to attempt to set up the
 426  * basic infrastructure used for Cross Partition Communication with the newly
 427  * upped partition.
 428  *
 429  * The kthread that was created by XPC HB and which setup the XPC
 430  * infrastructure will remain assigned to the partition until the partition
 431  * goes down. At which time the kthread will teardown the XPC infrastructure
 432  * and then exit.
 433  *
 434  * XPC HB will put the remote partition's XPC per partition specific variables
 435  * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
 436  * calling xpc_partition_up().
 437  */
 438 static void
 439 xpc_partition_up(struct xpc_partition *part)
 440 {
 441         DBUG_ON(part->channels != NULL);
 442
 443         dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
 444
 445         if (xpc_setup_infrastructure(part) != xpcSuccess) {
 446                 return;
 447         }
 448
 449         /*
 450          * The kthread that XPC HB called us with will become the
 451          * channel manager for this partition. It will not return
 452          * back to XPC HB until the partition's XPC infrastructure
 453          * has been dismantled.
 454          */
 455
 456         (void) xpc_part_ref(part);      /* this will always succeed */
 457
 458         if (xpc_make_first_contact(part) == xpcSuccess) {
 459                 xpc_channel_mgr(part);
 460         }
 461
 462         xpc_part_deref(part);
 463
 464         xpc_teardown_infrastructure(part);
 465 }
 466
 467
 468 static int
 469 xpc_activating(void *__partid)
 470 {
 471         partid_t partid = (u64) __partid;
 472         struct xpc_partition *part = &xpc_partitions[partid];
 473         unsigned long irq_flags;
 474         struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 475         int ret;
 476
 477
 478         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 479
 480         spin_lock_irqsave(&part->act_lock, irq_flags);
 481
 482         if (part->act_state == XPC_P_DEACTIVATING) {
 483                 part->act_state = XPC_P_INACTIVE;
 484                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 485                 part->remote_rp_pa = 0;
 486                 return 0;
 487         }
 488
 489         /* indicate the thread is activating */
 490         DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
 491         part->act_state = XPC_P_ACTIVATING;
 492
 493         XPC_SET_REASON(part, 0, 0);
 494         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 495
 496         dev_dbg(xpc_part, "bringing partition %d up\n", partid);
 497
 498         daemonize("xpc%02d", partid);
 499
 500         /*
 501          * This thread needs to run at a realtime priority to prevent a
 502          * significant performance degradation.
 503          */
 504         ret = sched_setscheduler(current, SCHED_FIFO, &param);
 505         if (ret != 0) {
 506                 dev_warn(xpc_part, "unable to set pid %d to a realtime "
 507                         "priority, ret=%d\n", current->pid, ret);
 508         }
 509
 510         /* allow this thread and its children to run on any CPU */
 511         set_cpus_allowed(current, CPU_MASK_ALL);
 512
 513         /*
 514          * Register the remote partition's AMOs with SAL so it can handle
 515          * and cleanup errors within that address range should the remote
 516          * partition go down. We don't unregister this range because it is
 517          * difficult to tell when outstanding writes to the remote partition
 518          * are finished and thus when it is safe to unregister. This should
 519          * not result in wasted space in the SAL xp_addr_region table because
 520          * we should get the same page for remote_amos_page_pa after module
 521          * reloads and system reboots.
 522          */
 523         if (sn_register_xp_addr_region(part->remote_amos_page_pa,
 524                                                         PAGE_SIZE, 1) < 0) {
 525                 dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
 526                         "xp_addr region\n", partid);
 527
 528                 spin_lock_irqsave(&part->act_lock, irq_flags);
 529                 part->act_state = XPC_P_INACTIVE;
 530                 XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
 531                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 532                 part->remote_rp_pa = 0;
 533                 return 0;
 534         }
 535
 536         xpc_allow_hb(partid, xpc_vars);
 537         xpc_IPI_send_activated(part);
 538
 539
 540         /*
 541          * xpc_partition_up() holds this thread and marks this partition as
 542          * XPC_P_ACTIVE by calling xpc_hb_mark_active().
 543          */
 544         (void) xpc_partition_up(part);
 545
 546         xpc_disallow_hb(partid, xpc_vars);
 547         xpc_mark_partition_inactive(part);
 548
 549         if (part->reason == xpcReactivating) {
 550                 /* interrupting ourselves results in activating partition */
 551                 xpc_IPI_send_reactivate(part);
 552         }
 553
 554         return 0;
 555 }
 556
 557
 558 void
 559 xpc_activate_partition(struct xpc_partition *part)
 560 {
 561         partid_t partid = XPC_PARTID(part);
 562         unsigned long irq_flags;
 563         pid_t pid;
 564
 565
 566         spin_lock_irqsave(&part->act_lock, irq_flags);
 567
 568         DBUG_ON(part->act_state != XPC_P_INACTIVE);
 569
 570         part->act_state = XPC_P_ACTIVATION_REQ;
 571         XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
 572
 573         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 574
 575         pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
 576
 577         if (unlikely(pid <= 0)) {
 578                 spin_lock_irqsave(&part->act_lock, irq_flags);
 579                 part->act_state = XPC_P_INACTIVE;
 580                 XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
 581                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 582         }
 583 }
 584
 585
 586 /*
 587  * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
 588  * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
 589  * than one partition, we use an AMO_t structure per partition to indicate
 590  * whether a partition has sent an IPI or not.  >>> If it has, then wake up the
 591  * associated kthread to handle it.
 592  *
 593  * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
 594  * running on other partitions.
 595  *
 596  * Noteworthy Arguments:
 597  *
 598  *      irq - Interrupt ReQuest number. NOT USED.
 599  *
 600  *      dev_id - partid of IPI's potential sender.
 601  */
 602 irqreturn_t
 603 xpc_notify_IRQ_handler(int irq, void *dev_id)
 604 {
 605         partid_t partid = (partid_t) (u64) dev_id;
 606         struct xpc_partition *part = &xpc_partitions[partid];
 607
 608
 609         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 610
 611         if (xpc_part_ref(part)) {
 612                 xpc_check_for_channel_activity(part);
 613
 614                 xpc_part_deref(part);
 615         }
 616         return IRQ_HANDLED;
 617 }
 618
 619
 620 /*
 621  * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
 622  * because the write to their associated IPI amo completed after the IRQ/IPI
 623  * was received.
 624  */
 625 void
 626 xpc_dropped_IPI_check(struct xpc_partition *part)
 627 {
 628         if (xpc_part_ref(part)) {
 629                 xpc_check_for_channel_activity(part);
 630
 631                 part->dropped_IPI_timer.expires = jiffies +
 632                                                         XPC_P_DROPPED_IPI_WAIT;
 633                 add_timer(&part->dropped_IPI_timer);
 634                 xpc_part_deref(part);
 635         }
 636 }
 637
 638
 639 void
 640 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
 641 {
 642         int idle = atomic_read(&ch->kthreads_idle);
 643         int assigned = atomic_read(&ch->kthreads_assigned);
 644         int wakeup;
 645
 646
 647         DBUG_ON(needed <= 0);
 648
 649         if (idle > 0) {
 650                 wakeup = (needed > idle) ? idle : needed;
 651                 needed -= wakeup;
 652
 653                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
 654                         "channel=%d\n", wakeup, ch->partid, ch->number);
 655
 656                 /* only wakeup the requested number of kthreads */
 657                 wake_up_nr(&ch->idle_wq, wakeup);
 658         }
 659
 660         if (needed <= 0) {
 661                 return;
 662         }
 663
 664         if (needed + assigned > ch->kthreads_assigned_limit) {
 665                 needed = ch->kthreads_assigned_limit - assigned;
 666                 // >>>should never be less than 0
 667                 if (needed <= 0) {
 668                         return;
 669                 }
 670         }
 671
 672         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
 673                 needed, ch->partid, ch->number);
 674
 675         xpc_create_kthreads(ch, needed, 0);
 676 }
 677
 678
 679 /*
 680  * This function is where XPC's kthreads wait for messages to deliver.
 681  */
 682 static void
 683 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
 684 {
 685         do {
 686                 /* deliver messages to their intended recipients */
 687
 688                 while ((volatile s64) ch->w_local_GP.get <
 689                                 (volatile s64) ch->w_remote_GP.put &&
 690                                         !((volatile u32) ch->flags &
 691                                                 XPC_C_DISCONNECTING)) {
 692                         xpc_deliver_msg(ch);
 693                 }
 694
 695                 if (atomic_inc_return(&ch->kthreads_idle) >
 696                                                 ch->kthreads_idle_limit) {
 697                         /* too many idle kthreads on this channel */
 698                         atomic_dec(&ch->kthreads_idle);
 699                         break;
 700                 }
 701
 702                 dev_dbg(xpc_chan, "idle kthread calling "
 703                         "wait_event_interruptible_exclusive()\n");
 704
 705                 (void) wait_event_interruptible_exclusive(ch->idle_wq,
 706                                 ((volatile s64) ch->w_local_GP.get <
 707                                         (volatile s64) ch->w_remote_GP.put ||
 708                                 ((volatile u32) ch->flags &
 709                                                 XPC_C_DISCONNECTING)));
 710
 711                 atomic_dec(&ch->kthreads_idle);
 712
 713         } while (!((volatile u32) ch->flags & XPC_C_DISCONNECTING));
 714 }
 715
 716
 717 static int
 718 xpc_daemonize_kthread(void *args)
 719 {
 720         partid_t partid = XPC_UNPACK_ARG1(args);
 721         u16 ch_number = XPC_UNPACK_ARG2(args);
 722         struct xpc_partition *part = &xpc_partitions[partid];
 723         struct xpc_channel *ch;
 724         int n_needed;
 725         unsigned long irq_flags;
 726
 727
 728         daemonize("xpc%02dc%d", partid, ch_number);
 729
 730         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
 731                 partid, ch_number);
 732
 733         ch = &part->channels[ch_number];
 734
 735         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 736
 737                 /* let registerer know that connection has been established */
 738
 739                 spin_lock_irqsave(&ch->lock, irq_flags);
 740                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
 741                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
 742                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 743
 744                         xpc_connected_callout(ch);
 745
 746                         spin_lock_irqsave(&ch->lock, irq_flags);
 747                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
 748                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 749
 750                         /*
 751                          * It is possible that while the callout was being
 752                          * made that the remote partition sent some messages.
 753                          * If that is the case, we may need to activate
 754                          * additional kthreads to help deliver them. We only
 755                          * need one less than total #of messages to deliver.
 756                          */
 757                         n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
 758                         if (n_needed > 0 &&
 759                                         !(ch->flags & XPC_C_DISCONNECTING)) {
 760                                 xpc_activate_kthreads(ch, n_needed);
 761                         }
 762                 } else {
 763                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 764                 }
 765
 766                 xpc_kthread_waitmsgs(part, ch);
 767         }
 768
 769         /* let registerer know that connection is disconnecting */
 770
 771         spin_lock_irqsave(&ch->lock, irq_flags);
 772         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 773                         !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 774                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
 775                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 776
 777                 xpc_disconnect_callout(ch, xpcDisconnecting);
 778
 779                 spin_lock_irqsave(&ch->lock, irq_flags);
 780                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
 781         }
 782         spin_unlock_irqrestore(&ch->lock, irq_flags);
 783
 784         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
 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         xpc_msgqueue_deref(ch);
 792
 793         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 794                 partid, ch_number);
 795
 796         xpc_part_deref(part);
 797         return 0;
 798 }
 799
 800
 801 /*
 802  * For each partition that XPC has established communications with, there is
 803  * a minimum of one kernel thread assigned to perform any operation that
 804  * may potentially sleep or block (basically the callouts to the asynchronous
 805  * functions registered via xpc_connect()).
 806  *
 807  * Additional kthreads are created and destroyed by XPC as the workload
 808  * demands.
 809  *
 810  * A kthread is assigned to one of the active channels that exists for a given
 811  * partition.
 812  */
 813 void
 814 xpc_create_kthreads(struct xpc_channel *ch, int needed,
 815                         int ignore_disconnecting)
 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                 if (ignore_disconnecting) {
 831                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
 832                                 /* kthreads assigned had gone to zero */
 833                                 BUG_ON(!(ch->flags &
 834                                         XPC_C_DISCONNECTINGCALLOUT_MADE));
 835                                 break;
 836                         }
 837
 838                 } else if (ch->flags & XPC_C_DISCONNECTING) {
 839                         break;
 840
 841                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1) {
 842                         if (atomic_inc_return(&part->nchannels_engaged) == 1)
 843                                 xpc_mark_partition_engaged(part);
 844                 }
 845                 (void) xpc_part_ref(part);
 846                 xpc_msgqueue_ref(ch);
 847
 848                 pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
 849                 if (pid < 0) {
 850                         /* the fork failed */
 851
 852                         /*
 853                          * NOTE: if (ignore_disconnecting &&
 854                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
 855                          * then we'll deadlock if all other kthreads assigned
 856                          * to this channel are blocked in the channel's
 857                          * registerer, because the only thing that will unblock
 858                          * them is the xpcDisconnecting callout that this
 859                          * failed kernel_thread would have made.
 860                          */
 861
 862                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 863                             atomic_dec_return(&part->nchannels_engaged) == 0) {
 864                                 xpc_mark_partition_disengaged(part);
 865                                 xpc_IPI_send_disengage(part);
 866                         }
 867                         xpc_msgqueue_deref(ch);
 868                         xpc_part_deref(part);
 869
 870                         if (atomic_read(&ch->kthreads_assigned) <
 871                                                 ch->kthreads_idle_limit) {
 872                                 /*
 873                                  * Flag this as an error only if we have an
 874                                  * insufficient #of kthreads for the channel
 875                                  * to function.
 876                                  */
 877                                 spin_lock_irqsave(&ch->lock, irq_flags);
 878                                 XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
 879                                                                 &irq_flags);
 880                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 881                         }
 882                         break;
 883                 }
 884
 885                 ch->kthreads_created++; // >>> temporary debug only!!!
 886         }
 887 }
 888
 889
 890 void
 891 xpc_disconnect_wait(int ch_number)
 892 {
 893         unsigned long irq_flags;
 894         partid_t partid;
 895         struct xpc_partition *part;
 896         struct xpc_channel *ch;
 897         int wakeup_channel_mgr;
 898
 899
 900         /* now wait for all callouts to the caller's function to cease */
 901         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 902                 part = &xpc_partitions[partid];
 903
 904                 if (!xpc_part_ref(part)) {
 905                         continue;
 906                 }
 907
 908                 ch = &part->channels[ch_number];
 909
 910                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
 911                         xpc_part_deref(part);
 912                         continue;
 913                 }
 914
 915                 wait_for_completion(&ch->wdisconnect_wait);
 916
 917                 spin_lock_irqsave(&ch->lock, irq_flags);
 918                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 919                 wakeup_channel_mgr = 0;
 920
 921                 if (ch->delayed_IPI_flags) {
 922                         if (part->act_state != XPC_P_DEACTIVATING) {
 923                                 spin_lock(&part->IPI_lock);
 924                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 925                                         ch->number, ch->delayed_IPI_flags);
 926                                 spin_unlock(&part->IPI_lock);
 927                                 wakeup_channel_mgr = 1;
 928                         }
 929                         ch->delayed_IPI_flags = 0;
 930                 }
 931
 932                 ch->flags &= ~XPC_C_WDISCONNECT;
 933                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 934
 935                 if (wakeup_channel_mgr) {
 936                         xpc_wakeup_channel_mgr(part);
 937                 }
 938
 939                 xpc_part_deref(part);
 940         }
 941 }
 942
 943
 944 static void
 945 xpc_do_exit(enum xpc_retval reason)
 946 {
 947         partid_t partid;
 948         int active_part_count, printed_waiting_msg = 0;
 949         struct xpc_partition *part;
 950         unsigned long printmsg_time, disengage_request_timeout = 0;
 951
 952
 953         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 954         DBUG_ON(xpc_exiting == 1);
 955
 956         /*
 957          * Let the heartbeat checker thread and the discovery thread
 958          * (if one is running) know that they should exit. Also wake up
 959          * the heartbeat checker thread in case it's sleeping.
 960          */
 961         xpc_exiting = 1;
 962         wake_up_interruptible(&xpc_act_IRQ_wq);
 963
 964         /* ignore all incoming interrupts */
 965         free_irq(SGI_XPC_ACTIVATE, NULL);
 966
 967         /* wait for the discovery thread to exit */
 968         wait_for_completion(&xpc_discovery_exited);
 969
 970         /* wait for the heartbeat checker thread to exit */
 971         wait_for_completion(&xpc_hb_checker_exited);
 972
 973
 974         /* sleep for a 1/3 of a second or so */
 975         (void) msleep_interruptible(300);
 976
 977
 978         /* wait for all partitions to become inactive */
 979
 980         printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 981         xpc_disengage_request_timedout = 0;
 982
 983         do {
 984                 active_part_count = 0;
 985
 986                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 987                         part = &xpc_partitions[partid];
 988
 989                         if (xpc_partition_disengaged(part) &&
 990                                         part->act_state == XPC_P_INACTIVE) {
 991                                 continue;
 992                         }
 993
 994                         active_part_count++;
 995
 996                         XPC_DEACTIVATE_PARTITION(part, reason);
 997
 998                         if (part->disengage_request_timeout >
 999                                                 disengage_request_timeout) {
1000                                 disengage_request_timeout =
1001                                                 part->disengage_request_timeout;
1002                         }
1003                 }
1004
1005                 if (xpc_partition_engaged(-1UL)) {
1006                         if (time_after(jiffies, printmsg_time)) {
1007                                 dev_info(xpc_part, "waiting for remote "
1008                                         "partitions to disengage, timeout in "
1009                                         "%ld seconds\n",
1010                                         (disengage_request_timeout - jiffies)
1011                                                                         / HZ);
1012                                 printmsg_time = jiffies +
1013                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
1014                                 printed_waiting_msg = 1;
1015                         }
1016
1017                 } else if (active_part_count > 0) {
1018                         if (printed_waiting_msg) {
1019                                 dev_info(xpc_part, "waiting for local partition"
1020                                         " to disengage\n");
1021                                 printed_waiting_msg = 0;
1022                         }
1023
1024                 } else {
1025                         if (!xpc_disengage_request_timedout) {
1026                                 dev_info(xpc_part, "all partitions have "
1027                                         "disengaged\n");
1028                         }
1029                         break;
1030                 }
1031
1032                 /* sleep for a 1/3 of a second or so */
1033                 (void) msleep_interruptible(300);
1034
1035         } while (1);
1036
1037         DBUG_ON(xpc_partition_engaged(-1UL));
1038
1039
1040         /* indicate to others that our reserved page is uninitialized */
1041         xpc_rsvd_page->vars_pa = 0;
1042
1043         /* now it's time to eliminate our heartbeat */
1044         del_timer_sync(&xpc_hb_timer);
1045         DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
1046
1047         if (reason == xpcUnloading) {
1048                 /* take ourselves off of the reboot_notifier_list */
1049                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1050
1051                 /* take ourselves off of the die_notifier list */
1052                 (void) unregister_die_notifier(&xpc_die_notifier);
1053         }
1054
1055         /* close down protections for IPI operations */
1056         xpc_restrict_IPI_ops();
1057
1058
1059         /* clear the interface to XPC's functions */
1060         xpc_clear_interface();
1061
1062         if (xpc_sysctl) {
1063                 unregister_sysctl_table(xpc_sysctl);
1064         }
1065
1066         kfree(xpc_remote_copy_buffer_base);
1067 }
1068
1069
1070 /*
1071  * This function is called when the system is being rebooted.
1072  */
1073 static int
1074 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1075 {
1076         enum xpc_retval reason;
1077
1078
1079         switch (event) {
1080         case SYS_RESTART:
1081                 reason = xpcSystemReboot;
1082                 break;
1083         case SYS_HALT:
1084                 reason = xpcSystemHalt;
1085                 break;
1086         case SYS_POWER_OFF:
1087                 reason = xpcSystemPoweroff;
1088                 break;
1089         default:
1090                 reason = xpcSystemGoingDown;
1091         }
1092
1093         xpc_do_exit(reason);
1094         return NOTIFY_DONE;
1095 }
1096
1097
1098 /*
1099  * Notify other partitions to disengage from all references to our memory.
1100  */
1101 static void
1102 xpc_die_disengage(void)
1103 {
1104         struct xpc_partition *part;
1105         partid_t partid;
1106         unsigned long engaged;
1107         long time, printmsg_time, disengage_request_timeout;
1108
1109
1110         /* keep xpc_hb_checker thread from doing anything (just in case) */
1111         xpc_exiting = 1;
1112
1113         xpc_vars->heartbeating_to_mask = 0;  /* indicate we're deactivated */
1114
1115         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1116                 part = &xpc_partitions[partid];
1117
1118                 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
1119                                                         remote_vars_version)) {
1120
1121                         /* just in case it was left set by an earlier XPC */
1122                         xpc_clear_partition_engaged(1UL << partid);
1123                         continue;
1124                 }
1125
1126                 if (xpc_partition_engaged(1UL << partid) ||
1127                                         part->act_state != XPC_P_INACTIVE) {
1128                         xpc_request_partition_disengage(part);
1129                         xpc_mark_partition_disengaged(part);
1130                         xpc_IPI_send_disengage(part);
1131                 }
1132         }
1133
1134         time = rtc_time();
1135         printmsg_time = time +
1136                 (XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
1137         disengage_request_timeout = time +
1138                 (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1139
1140         /* wait for all other partitions to disengage from us */
1141
1142         while (1) {
1143                 engaged = xpc_partition_engaged(-1UL);
1144                 if (!engaged) {
1145                         dev_info(xpc_part, "all partitions have disengaged\n");
1146                         break;
1147                 }
1148
1149                 time = rtc_time();
1150                 if (time >= disengage_request_timeout) {
1151                         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1152                                 if (engaged & (1UL << partid)) {
1153                                         dev_info(xpc_part, "disengage from "
1154                                                 "remote partition %d timed "
1155                                                 "out\n", partid);
1156                                 }
1157                         }
1158                         break;
1159                 }
1160
1161                 if (time >= printmsg_time) {
1162                         dev_info(xpc_part, "waiting for remote partitions to "
1163                                 "disengage, timeout in %ld seconds\n",
1164                                 (disengage_request_timeout - time) /
1165                                                 sn_rtc_cycles_per_second);
1166                         printmsg_time = time +
1167                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1168                                                 sn_rtc_cycles_per_second);
1169                 }
1170         }
1171 }
1172
1173
1174 /*
1175  * This function is called when the system is being restarted or halted due
1176  * to some sort of system failure. If this is the case we need to notify the
1177  * other partitions to disengage from all references to our memory.
1178  * This function can also be called when our heartbeater could be offlined
1179  * for a time. In this case we need to notify other partitions to not worry
1180  * about the lack of a heartbeat.
1181  */
1182 static int
1183 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1184 {
1185         switch (event) {
1186         case DIE_MACHINE_RESTART:
1187         case DIE_MACHINE_HALT:
1188                 xpc_die_disengage();
1189                 break;
1190
1191         case DIE_KDEBUG_ENTER:
1192                 xpc_kdebug_entered = 1;
1193
1194                 /* Should lack of heartbeat be ignored by other partitions? */
1195                 if (!xpc_kdebug_ignore) {
1196                         break;
1197                 }
1198                 /* fall through */
1199         case DIE_MCA_MONARCH_ENTER:
1200         case DIE_INIT_MONARCH_ENTER:
1201                 xpc_vars->heartbeat++;
1202                 xpc_vars->heartbeat_offline = 1;
1203                 break;
1204
1205         case DIE_KDEBUG_LEAVE:
1206                 xpc_kdebug_entered = 0;
1207
1208                 /* Is lack of heartbeat being ignored by other partitions? */
1209                 if (!xpc_kdebug_ignore) {
1210                         break;
1211                 }
1212                 /* fall through */
1213         case DIE_MCA_MONARCH_LEAVE:
1214         case DIE_INIT_MONARCH_LEAVE:
1215                 xpc_vars->heartbeat++;
1216                 xpc_vars->heartbeat_offline = 0;
1217                 break;
1218         }
1219
1220         return NOTIFY_DONE;
1221 }
1222
1223
1224 int
1225 xpc_kdebug_force_disengage(void)
1226 {
1227         if (!xpc_kdebug_entered) {
1228                 /* not being called from kdebug */
1229                 return 1;
1230         }
1231
1232         xpc_vars->heartbeat_offline = 0;
1233         xpc_die_disengage();
1234         return 0;
1235 }
1236 EXPORT_SYMBOL_GPL(xpc_kdebug_force_disengage);
1237
1238
1239 int __init
1240 xpc_init(void)
1241 {
1242         int ret;
1243         partid_t partid;
1244         struct xpc_partition *part;
1245         pid_t pid;
1246         size_t buf_size;
1247
1248
1249         if (!ia64_platform_is("sn2")) {
1250                 return -ENODEV;
1251         }
1252
1253
1254         buf_size = max(XPC_RP_VARS_SIZE,
1255                                 XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES);
1256         xpc_remote_copy_buffer = xpc_kmalloc_cacheline_aligned(buf_size,
1257                                      GFP_KERNEL, &xpc_remote_copy_buffer_base);
1258         if (xpc_remote_copy_buffer == NULL)
1259                 return -ENOMEM;
1260
1261         snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1262         snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1263
1264         xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1265
1266         /*
1267          * The first few fields of each entry of xpc_partitions[] need to
1268          * be initialized now so that calls to xpc_connect() and
1269          * xpc_disconnect() can be made prior to the activation of any remote
1270          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1271          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1272          * PARTITION HAS BEEN ACTIVATED.
1273          */
1274         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1275                 part = &xpc_partitions[partid];
1276
1277                 DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
1278
1279                 part->act_IRQ_rcvd = 0;
1280                 spin_lock_init(&part->act_lock);
1281                 part->act_state = XPC_P_INACTIVE;
1282                 XPC_SET_REASON(part, 0, 0);
1283
1284                 init_timer(&part->disengage_request_timer);
1285                 part->disengage_request_timer.function =
1286                                 xpc_timeout_partition_disengage_request;
1287                 part->disengage_request_timer.data = (unsigned long) part;
1288
1289                 part->setup_state = XPC_P_UNSET;
1290                 init_waitqueue_head(&part->teardown_wq);
1291                 atomic_set(&part->references, 0);
1292         }
1293
1294         /*
1295          * Open up protections for IPI operations (and AMO operations on
1296          * Shub 1.1 systems).
1297          */
1298         xpc_allow_IPI_ops();
1299
1300         /*
1301          * Interrupts being processed will increment this atomic variable and
1302          * awaken the heartbeat thread which will process the interrupts.
1303          */
1304         atomic_set(&xpc_act_IRQ_rcvd, 0);
1305
1306         /*
1307          * This is safe to do before the xpc_hb_checker thread has started
1308          * because the handler releases a wait queue.  If an interrupt is
1309          * received before the thread is waiting, it will not go to sleep,
1310          * but rather immediately process the interrupt.
1311          */
1312         ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1313                                                         "xpc hb", NULL);
1314         if (ret != 0) {
1315                 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1316                         "errno=%d\n", -ret);
1317
1318                 xpc_restrict_IPI_ops();
1319
1320                 if (xpc_sysctl) {
1321                         unregister_sysctl_table(xpc_sysctl);
1322                 }
1323
1324                 kfree(xpc_remote_copy_buffer_base);
1325                 return -EBUSY;
1326         }
1327
1328         /*
1329          * Fill the partition reserved page with the information needed by
1330          * other partitions to discover we are alive and establish initial
1331          * communications.
1332          */
1333         xpc_rsvd_page = xpc_rsvd_page_init();
1334         if (xpc_rsvd_page == NULL) {
1335                 dev_err(xpc_part, "could not setup our reserved page\n");
1336
1337                 free_irq(SGI_XPC_ACTIVATE, NULL);
1338                 xpc_restrict_IPI_ops();
1339
1340                 if (xpc_sysctl) {
1341                         unregister_sysctl_table(xpc_sysctl);
1342                 }
1343
1344                 kfree(xpc_remote_copy_buffer_base);
1345                 return -EBUSY;
1346         }
1347
1348
1349         /* add ourselves to the reboot_notifier_list */
1350         ret = register_reboot_notifier(&xpc_reboot_notifier);
1351         if (ret != 0) {
1352                 dev_warn(xpc_part, "can't register reboot notifier\n");
1353         }
1354
1355         /* add ourselves to the die_notifier list */
1356         ret = register_die_notifier(&xpc_die_notifier);
1357         if (ret != 0) {
1358                 dev_warn(xpc_part, "can't register die notifier\n");
1359         }
1360
1361
1362         /*
1363          * Set the beating to other partitions into motion.  This is
1364          * the last requirement for other partitions' discovery to
1365          * initiate communications with us.
1366          */
1367         init_timer(&xpc_hb_timer);
1368         xpc_hb_timer.function = xpc_hb_beater;
1369         xpc_hb_beater(0);
1370
1371
1372         /*
1373          * The real work-horse behind xpc.  This processes incoming
1374          * interrupts and monitors remote heartbeats.
1375          */
1376         pid = kernel_thread(xpc_hb_checker, NULL, 0);
1377         if (pid < 0) {
1378                 dev_err(xpc_part, "failed while forking hb check thread\n");
1379
1380                 /* indicate to others that our reserved page is uninitialized */
1381                 xpc_rsvd_page->vars_pa = 0;
1382
1383                 /* take ourselves off of the reboot_notifier_list */
1384                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1385
1386                 /* take ourselves off of the die_notifier list */
1387                 (void) unregister_die_notifier(&xpc_die_notifier);
1388
1389                 del_timer_sync(&xpc_hb_timer);
1390                 free_irq(SGI_XPC_ACTIVATE, NULL);
1391                 xpc_restrict_IPI_ops();
1392
1393                 if (xpc_sysctl) {
1394                         unregister_sysctl_table(xpc_sysctl);
1395                 }
1396
1397                 kfree(xpc_remote_copy_buffer_base);
1398                 return -EBUSY;
1399         }
1400
1401
1402         /*
1403          * Startup a thread that will attempt to discover other partitions to
1404          * activate based on info provided by SAL. This new thread is short
1405          * lived and will exit once discovery is complete.
1406          */
1407         pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
1408         if (pid < 0) {
1409                 dev_err(xpc_part, "failed while forking discovery thread\n");
1410
1411                 /* mark this new thread as a non-starter */
1412                 complete(&xpc_discovery_exited);
1413
1414                 xpc_do_exit(xpcUnloading);
1415                 return -EBUSY;
1416         }
1417
1418
1419         /* set the interface to point at XPC's functions */
1420         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1421                           xpc_initiate_allocate, xpc_initiate_send,
1422                           xpc_initiate_send_notify, xpc_initiate_received,
1423                           xpc_initiate_partid_to_nasids);
1424
1425         return 0;
1426 }
1427 module_init(xpc_init);
1428
1429
1430 void __exit
1431 xpc_exit(void)
1432 {
1433         xpc_do_exit(xpcUnloading);
1434 }
1435 module_exit(xpc_exit);
1436
1437
1438 MODULE_AUTHOR("Silicon Graphics, Inc.");
1439 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1440 MODULE_LICENSE("GPL");
1441
1442 module_param(xpc_hb_interval, int, 0);
1443 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1444                 "heartbeat increments.");
1445
1446 module_param(xpc_hb_check_interval, int, 0);
1447 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1448                 "heartbeat checks.");
1449
1450 module_param(xpc_disengage_request_timelimit, int, 0);
1451 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1452                 "for disengage request to complete.");
1453
1454 module_param(xpc_kdebug_ignore, int, 0);
1455 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1456                 "other partitions when dropping into kdebug.");
1457