drivers/misc/sgi-xp/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) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
   7  */
   8
   9 /*
  10  * Cross Partition Communication (XPC) support - standard version.
  11  *
  12  *      XPC provides a message passing capability that crosses partition
  13  *      boundaries. This module is made up of two parts:
  14  *
  15  *          partition   This part detects the presence/absence of other
  16  *                      partitions. It provides a heartbeat and monitors
  17  *                      the heartbeats of other partitions.
  18  *
  19  *          channel     This part manages the channels and sends/receives
  20  *                      messages across them to/from other partitions.
  21  *
  22  *      There are a couple of additional functions residing in XP, which
  23  *      provide an interface to XPC for its users.
  24  *
  25  *
  26  *      Caveats:
  27  *
  28  *        . We currently have no way to determine which nasid an IPI came
  29  *          from. Thus, xpc_IPI_send() does a remote AMO write followed by
  30  *          an IPI. The AMO indicates where data is to be pulled from, so
  31  *          after the IPI arrives, the remote partition checks the AMO word.
  32  *          The IPI can actually arrive before the AMO however, so other code
  33  *          must periodically check for this case. Also, remote AMO operations
  34  *          do not reliably time out. Thus we do a remote PIO read solely to
  35  *          know whether the remote partition is down and whether we should
  36  *          stop sending IPIs to it. This remote PIO read operation is set up
  37  *          in a special nofault region so SAL knows to ignore (and cleanup)
  38  *          any errors due to the remote AMO write, PIO read, and/or PIO
  39  *          write operations.
  40  *
  41  *          If/when new hardware solves this IPI problem, we should abandon
  42  *          the current approach.
  43  *
  44  */
  45
  46 #include <linux/kernel.h>
  47 #include <linux/module.h>
  48 #include <linux/init.h>
  49 #include <linux/sched.h>
  50 #include <linux/syscalls.h>
  51 #include <linux/cache.h>
  52 #include <linux/interrupt.h>
  53 #include <linux/delay.h>
  54 #include <linux/reboot.h>
  55 #include <linux/completion.h>
  56 #include <linux/kdebug.h>
  57 #include <asm/sn/intr.h>
  58 #include <asm/sn/sn_sal.h>
  59 #include <asm/uaccess.h>
  60 #include "xpc.h"
  61
  62 /* define two XPC debug device structures to be used with dev_dbg() et al */
  63
  64 struct device_driver xpc_dbg_name = {
  65         .name = "xpc"
  66 };
  67
  68 struct device xpc_part_dbg_subname = {
  69         .bus_id = {0},          /* set to "part" at xpc_init() time */
  70         .driver = &xpc_dbg_name
  71 };
  72
  73 struct device xpc_chan_dbg_subname = {
  74         .bus_id = {0},          /* set to "chan" at xpc_init() time */
  75         .driver = &xpc_dbg_name
  76 };
  77
  78 struct device *xpc_part = &xpc_part_dbg_subname;
  79 struct device *xpc_chan = &xpc_chan_dbg_subname;
  80
  81 static int xpc_kdebug_ignore;
  82
  83 /* systune related variables for /proc/sys directories */
  84
  85 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
  86 static int xpc_hb_min_interval = 1;
  87 static int xpc_hb_max_interval = 10;
  88
  89 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
  90 static int xpc_hb_check_min_interval = 10;
  91 static int xpc_hb_check_max_interval = 120;
  92
  93 int xpc_disengage_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
  94 static int xpc_disengage_request_min_timelimit = 0;
  95 static int xpc_disengage_request_max_timelimit = 120;
  96
  97 static ctl_table xpc_sys_xpc_hb_dir[] = {
  98         {
  99          .ctl_name = CTL_UNNUMBERED,
 100          .procname = "hb_interval",
 101          .data = &xpc_hb_interval,
 102          .maxlen = sizeof(int),
 103          .mode = 0644,
 104          .proc_handler = &proc_dointvec_minmax,
 105          .strategy = &sysctl_intvec,
 106          .extra1 = &xpc_hb_min_interval,
 107          .extra2 = &xpc_hb_max_interval},
 108         {
 109          .ctl_name = CTL_UNNUMBERED,
 110          .procname = "hb_check_interval",
 111          .data = &xpc_hb_check_interval,
 112          .maxlen = sizeof(int),
 113          .mode = 0644,
 114          .proc_handler = &proc_dointvec_minmax,
 115          .strategy = &sysctl_intvec,
 116          .extra1 = &xpc_hb_check_min_interval,
 117          .extra2 = &xpc_hb_check_max_interval},
 118         {}
 119 };
 120 static ctl_table xpc_sys_xpc_dir[] = {
 121         {
 122          .ctl_name = CTL_UNNUMBERED,
 123          .procname = "hb",
 124          .mode = 0555,
 125          .child = xpc_sys_xpc_hb_dir},
 126         {
 127          .ctl_name = CTL_UNNUMBERED,
 128          .procname = "disengage_request_timelimit",
 129          .data = &xpc_disengage_request_timelimit,
 130          .maxlen = sizeof(int),
 131          .mode = 0644,
 132          .proc_handler = &proc_dointvec_minmax,
 133          .strategy = &sysctl_intvec,
 134          .extra1 = &xpc_disengage_request_min_timelimit,
 135          .extra2 = &xpc_disengage_request_max_timelimit},
 136         {}
 137 };
 138 static ctl_table xpc_sys_dir[] = {
 139         {
 140          .ctl_name = CTL_UNNUMBERED,
 141          .procname = "xpc",
 142          .mode = 0555,
 143          .child = xpc_sys_xpc_dir},
 144         {}
 145 };
 146 static struct ctl_table_header *xpc_sysctl;
 147
 148 /* non-zero if any remote partition disengage request was timed out */
 149 int xpc_disengage_request_timedout;
 150
 151 /* #of IRQs received */
 152 static atomic_t xpc_act_IRQ_rcvd;
 153
 154 /* IRQ handler notifies this wait queue on receipt of an IRQ */
 155 static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
 156
 157 static unsigned long xpc_hb_check_timeout;
 158
 159 /* notification that the xpc_hb_checker thread has exited */
 160 static DECLARE_COMPLETION(xpc_hb_checker_exited);
 161
 162 /* notification that the xpc_discovery thread has exited */
 163 static DECLARE_COMPLETION(xpc_discovery_exited);
 164
 165 static struct timer_list xpc_hb_timer;
 166
 167 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
 168
 169 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
 170 static struct notifier_block xpc_reboot_notifier = {
 171         .notifier_call = xpc_system_reboot,
 172 };
 173
 174 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
 175 static struct notifier_block xpc_die_notifier = {
 176         .notifier_call = xpc_system_die,
 177 };
 178
 179 /*
 180  * Timer function to enforce the timelimit on the partition disengage request.
 181  */
 182 static void
 183 xpc_timeout_partition_disengage_request(unsigned long data)
 184 {
 185         struct xpc_partition *part = (struct xpc_partition *)data;
 186
 187         DBUG_ON(time_before(jiffies, part->disengage_request_timeout));
 188
 189         (void)xpc_partition_disengaged(part);
 190
 191         DBUG_ON(part->disengage_request_timeout != 0);
 192         DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
 193 }
 194
 195 /*
 196  * Notify the heartbeat check thread that an IRQ has been received.
 197  */
 198 static irqreturn_t
 199 xpc_act_IRQ_handler(int irq, void *dev_id)
 200 {
 201         atomic_inc(&xpc_act_IRQ_rcvd);
 202         wake_up_interruptible(&xpc_act_IRQ_wq);
 203         return IRQ_HANDLED;
 204 }
 205
 206 /*
 207  * Timer to produce the heartbeat.  The timer structures function is
 208  * already set when this is initially called.  A tunable is used to
 209  * specify when the next timeout should occur.
 210  */
 211 static void
 212 xpc_hb_beater(unsigned long dummy)
 213 {
 214         xpc_vars->heartbeat++;
 215
 216         if (time_after_eq(jiffies, xpc_hb_check_timeout)) {
 217                 wake_up_interruptible(&xpc_act_IRQ_wq);
 218         }
 219
 220         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
 221         add_timer(&xpc_hb_timer);
 222 }
 223
 224 /*
 225  * This thread is responsible for nearly all of the partition
 226  * activation/deactivation.
 227  */
 228 static int
 229 xpc_hb_checker(void *ignore)
 230 {
 231         int last_IRQ_count = 0;
 232         int new_IRQ_count;
 233         int force_IRQ = 0;
 234
 235         /* this thread was marked active by xpc_hb_init() */
 236
 237         daemonize(XPC_HB_CHECK_THREAD_NAME);
 238
 239         set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
 240
 241         /* set our heartbeating to other partitions into motion */
 242         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
 243         xpc_hb_beater(0);
 244
 245         while (!(volatile int)xpc_exiting) {
 246
 247                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
 248                         "been received\n",
 249                         (int)(xpc_hb_check_timeout - jiffies),
 250                         atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
 251
 252                 /* checking of remote heartbeats is skewed by IRQ handling */
 253                 if (time_after_eq(jiffies, xpc_hb_check_timeout)) {
 254                         dev_dbg(xpc_part, "checking remote heartbeats\n");
 255                         xpc_check_remote_hb();
 256
 257                         /*
 258                          * We need to periodically recheck to ensure no
 259                          * IPI/AMO pairs have been missed.  That check
 260                          * must always reset xpc_hb_check_timeout.
 261                          */
 262                         force_IRQ = 1;
 263                 }
 264
 265                 /* check for outstanding IRQs */
 266                 new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
 267                 if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
 268                         force_IRQ = 0;
 269
 270                         dev_dbg(xpc_part, "found an IRQ to process; will be "
 271                                 "resetting xpc_hb_check_timeout\n");
 272
 273                         last_IRQ_count += xpc_identify_act_IRQ_sender();
 274                         if (last_IRQ_count < new_IRQ_count) {
 275                                 /* retry once to help avoid missing AMO */
 276                                 (void)xpc_identify_act_IRQ_sender();
 277                         }
 278                         last_IRQ_count = new_IRQ_count;
 279
 280                         xpc_hb_check_timeout = jiffies +
 281                             (xpc_hb_check_interval * HZ);
 282                 }
 283
 284                 /* wait for IRQ or timeout */
 285                 (void)wait_event_interruptible(xpc_act_IRQ_wq,
 286                                                (last_IRQ_count <
 287                                                 atomic_read(&xpc_act_IRQ_rcvd)
 288                                                 || time_after_eq(jiffies,
 289                                                         xpc_hb_check_timeout) ||
 290                                                 (volatile int)xpc_exiting));
 291         }
 292
 293         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 294
 295         /* mark this thread as having exited */
 296         complete(&xpc_hb_checker_exited);
 297         return 0;
 298 }
 299
 300 /*
 301  * This thread will attempt to discover other partitions to activate
 302  * based on info provided by SAL. This new thread is short lived and
 303  * will exit once discovery is complete.
 304  */
 305 static int
 306 xpc_initiate_discovery(void *ignore)
 307 {
 308         daemonize(XPC_DISCOVERY_THREAD_NAME);
 309
 310         xpc_discovery();
 311
 312         dev_dbg(xpc_part, "discovery thread is exiting\n");
 313
 314         /* mark this thread as having exited */
 315         complete(&xpc_discovery_exited);
 316         return 0;
 317 }
 318
 319 /*
 320  * Establish first contact with the remote partititon. This involves pulling
 321  * the XPC per partition variables from the remote partition and waiting for
 322  * the remote partition to pull ours.
 323  */
 324 static enum xpc_retval
 325 xpc_make_first_contact(struct xpc_partition *part)
 326 {
 327         enum xpc_retval ret;
 328
 329         while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
 330                 if (ret != xpcRetry) {
 331                         XPC_DEACTIVATE_PARTITION(part, ret);
 332                         return ret;
 333                 }
 334
 335                 dev_dbg(xpc_chan, "waiting to make first contact with "
 336                         "partition %d\n", XPC_PARTID(part));
 337
 338                 /* wait a 1/4 of a second or so */
 339                 (void)msleep_interruptible(250);
 340
 341                 if (part->act_state == XPC_P_DEACTIVATING) {
 342                         return part->reason;
 343                 }
 344         }
 345
 346         return xpc_mark_partition_active(part);
 347 }
 348
 349 /*
 350  * The first kthread assigned to a newly activated partition is the one
 351  * created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
 352  * that kthread until the partition is brought down, at which time that kthread
 353  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
 354  * that XPC has dismantled all communication infrastructure for the associated
 355  * partition.) This kthread becomes the channel manager for that partition.
 356  *
 357  * Each active partition has a channel manager, who, besides connecting and
 358  * disconnecting channels, will ensure that each of the partition's connected
 359  * channels has the required number of assigned kthreads to get the work done.
 360  */
 361 static void
 362 xpc_channel_mgr(struct xpc_partition *part)
 363 {
 364         while (part->act_state != XPC_P_DEACTIVATING ||
 365                atomic_read(&part->nchannels_active) > 0 ||
 366                !xpc_partition_disengaged(part)) {
 367
 368                 xpc_process_channel_activity(part);
 369
 370                 /*
 371                  * Wait until we've been requested to activate kthreads or
 372                  * all of the channel's message queues have been torn down or
 373                  * a signal is pending.
 374                  *
 375                  * The channel_mgr_requests is set to 1 after being awakened,
 376                  * This is done to prevent the channel mgr from making one pass
 377                  * through the loop for each request, since he will
 378                  * be servicing all the requests in one pass. The reason it's
 379                  * set to 1 instead of 0 is so that other kthreads will know
 380                  * that the channel mgr is running and won't bother trying to
 381                  * wake him up.
 382                  */
 383                 atomic_dec(&part->channel_mgr_requests);
 384                 (void)wait_event_interruptible(part->channel_mgr_wq,
 385                                                (atomic_read
 386                                                 (&part->channel_mgr_requests) >
 387                                                 0 ||
 388                                                 (volatile u64)part->
 389                                                 local_IPI_amo != 0 ||
 390                                                 ((volatile u8)part->act_state ==
 391                                                  XPC_P_DEACTIVATING &&
 392                                                  atomic_read(&part->
 393                                                              nchannels_active)
 394                                                  == 0 &&
 395                                                  xpc_partition_disengaged
 396                                                  (part))));
 397                 atomic_set(&part->channel_mgr_requests, 1);
 398
 399                 // >>> Does it need to wakeup periodically as well? In case we
 400                 // >>> miscalculated the #of kthreads to wakeup or create?
 401         }
 402 }
 403
 404 /*
 405  * When XPC HB determines that a partition has come up, it will create a new
 406  * kthread and that kthread will call this function to attempt to set up the
 407  * basic infrastructure used for Cross Partition Communication with the newly
 408  * upped partition.
 409  *
 410  * The kthread that was created by XPC HB and which setup the XPC
 411  * infrastructure will remain assigned to the partition until the partition
 412  * goes down. At which time the kthread will teardown the XPC infrastructure
 413  * and then exit.
 414  *
 415  * XPC HB will put the remote partition's XPC per partition specific variables
 416  * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
 417  * calling xpc_partition_up().
 418  */
 419 static void
 420 xpc_partition_up(struct xpc_partition *part)
 421 {
 422         DBUG_ON(part->channels != NULL);
 423
 424         dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
 425
 426         if (xpc_setup_infrastructure(part) != xpcSuccess) {
 427                 return;
 428         }
 429
 430         /*
 431          * The kthread that XPC HB called us with will become the
 432          * channel manager for this partition. It will not return
 433          * back to XPC HB until the partition's XPC infrastructure
 434          * has been dismantled.
 435          */
 436
 437         (void)xpc_part_ref(part);       /* this will always succeed */
 438
 439         if (xpc_make_first_contact(part) == xpcSuccess) {
 440                 xpc_channel_mgr(part);
 441         }
 442
 443         xpc_part_deref(part);
 444
 445         xpc_teardown_infrastructure(part);
 446 }
 447
 448 static int
 449 xpc_activating(void *__partid)
 450 {
 451         partid_t partid = (u64)__partid;
 452         struct xpc_partition *part = &xpc_partitions[partid];
 453         unsigned long irq_flags;
 454         struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1 };
 455         int ret;
 456
 457         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 458
 459         spin_lock_irqsave(&part->act_lock, irq_flags);
 460
 461         if (part->act_state == XPC_P_DEACTIVATING) {
 462                 part->act_state = XPC_P_INACTIVE;
 463                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 464                 part->remote_rp_pa = 0;
 465                 return 0;
 466         }
 467
 468         /* indicate the thread is activating */
 469         DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
 470         part->act_state = XPC_P_ACTIVATING;
 471
 472         XPC_SET_REASON(part, 0, 0);
 473         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 474
 475         dev_dbg(xpc_part, "bringing partition %d up\n", partid);
 476
 477         daemonize("xpc%02d", partid);
 478
 479         /*
 480          * This thread needs to run at a realtime priority to prevent a
 481          * significant performance degradation.
 482          */
 483         ret = sched_setscheduler(current, SCHED_FIFO, &param);
 484         if (ret != 0) {
 485                 dev_warn(xpc_part, "unable to set pid %d to a realtime "
 486                          "priority, ret=%d\n", current->pid, ret);
 487         }
 488
 489         /* allow this thread and its children to run on any CPU */
 490         set_cpus_allowed(current, CPU_MASK_ALL);
 491
 492         /*
 493          * Register the remote partition's AMOs with SAL so it can handle
 494          * and cleanup errors within that address range should the remote
 495          * partition go down. We don't unregister this range because it is
 496          * difficult to tell when outstanding writes to the remote partition
 497          * are finished and thus when it is safe to unregister. This should
 498          * not result in wasted space in the SAL xp_addr_region table because
 499          * we should get the same page for remote_amos_page_pa after module
 500          * reloads and system reboots.
 501          */
 502         if (sn_register_xp_addr_region(part->remote_amos_page_pa,
 503                                        PAGE_SIZE, 1) < 0) {
 504                 dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
 505                          "xp_addr region\n", partid);
 506
 507                 spin_lock_irqsave(&part->act_lock, irq_flags);
 508                 part->act_state = XPC_P_INACTIVE;
 509                 XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
 510                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 511                 part->remote_rp_pa = 0;
 512                 return 0;
 513         }
 514
 515         xpc_allow_hb(partid, xpc_vars);
 516         xpc_IPI_send_activated(part);
 517
 518         /*
 519          * xpc_partition_up() holds this thread and marks this partition as
 520          * XPC_P_ACTIVE by calling xpc_hb_mark_active().
 521          */
 522         (void)xpc_partition_up(part);
 523
 524         xpc_disallow_hb(partid, xpc_vars);
 525         xpc_mark_partition_inactive(part);
 526
 527         if (part->reason == xpcReactivating) {
 528                 /* interrupting ourselves results in activating partition */
 529                 xpc_IPI_send_reactivate(part);
 530         }
 531
 532         return 0;
 533 }
 534
 535 void
 536 xpc_activate_partition(struct xpc_partition *part)
 537 {
 538         partid_t partid = XPC_PARTID(part);
 539         unsigned long irq_flags;
 540         pid_t pid;
 541
 542         spin_lock_irqsave(&part->act_lock, irq_flags);
 543
 544         DBUG_ON(part->act_state != XPC_P_INACTIVE);
 545
 546         part->act_state = XPC_P_ACTIVATION_REQ;
 547         XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
 548
 549         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 550
 551         pid = kernel_thread(xpc_activating, (void *)((u64)partid), 0);
 552
 553         if (unlikely(pid <= 0)) {
 554                 spin_lock_irqsave(&part->act_lock, irq_flags);
 555                 part->act_state = XPC_P_INACTIVE;
 556                 XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
 557                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 558         }
 559 }
 560
 561 /*
 562  * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
 563  * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
 564  * than one partition, we use an AMO_t structure per partition to indicate
 565  * whether a partition has sent an IPI or not.  >>> If it has, then wake up the
 566  * associated kthread to handle it.
 567  *
 568  * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
 569  * running on other partitions.
 570  *
 571  * Noteworthy Arguments:
 572  *
 573  *      irq - Interrupt ReQuest number. NOT USED.
 574  *
 575  *      dev_id - partid of IPI's potential sender.
 576  */
 577 irqreturn_t
 578 xpc_notify_IRQ_handler(int irq, void *dev_id)
 579 {
 580         partid_t partid = (partid_t) (u64)dev_id;
 581         struct xpc_partition *part = &xpc_partitions[partid];
 582
 583         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 584
 585         if (xpc_part_ref(part)) {
 586                 xpc_check_for_channel_activity(part);
 587
 588                 xpc_part_deref(part);
 589         }
 590         return IRQ_HANDLED;
 591 }
 592
 593 /*
 594  * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
 595  * because the write to their associated IPI amo completed after the IRQ/IPI
 596  * was received.
 597  */
 598 void
 599 xpc_dropped_IPI_check(struct xpc_partition *part)
 600 {
 601         if (xpc_part_ref(part)) {
 602                 xpc_check_for_channel_activity(part);
 603
 604                 part->dropped_IPI_timer.expires = jiffies +
 605                     XPC_P_DROPPED_IPI_WAIT;
 606                 add_timer(&part->dropped_IPI_timer);
 607                 xpc_part_deref(part);
 608         }
 609 }
 610
 611 void
 612 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
 613 {
 614         int idle = atomic_read(&ch->kthreads_idle);
 615         int assigned = atomic_read(&ch->kthreads_assigned);
 616         int wakeup;
 617
 618         DBUG_ON(needed <= 0);
 619
 620         if (idle > 0) {
 621                 wakeup = (needed > idle) ? idle : needed;
 622                 needed -= wakeup;
 623
 624                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
 625                         "channel=%d\n", wakeup, ch->partid, ch->number);
 626
 627                 /* only wakeup the requested number of kthreads */
 628                 wake_up_nr(&ch->idle_wq, wakeup);
 629         }
 630
 631         if (needed <= 0) {
 632                 return;
 633         }
 634
 635         if (needed + assigned > ch->kthreads_assigned_limit) {
 636                 needed = ch->kthreads_assigned_limit - assigned;
 637                 // >>>should never be less than 0
 638                 if (needed <= 0) {
 639                         return;
 640                 }
 641         }
 642
 643         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
 644                 needed, ch->partid, ch->number);
 645
 646         xpc_create_kthreads(ch, needed, 0);
 647 }
 648
 649 /*
 650  * This function is where XPC's kthreads wait for messages to deliver.
 651  */
 652 static void
 653 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
 654 {
 655         do {
 656                 /* deliver messages to their intended recipients */
 657
 658                 while ((volatile s64)ch->w_local_GP.get <
 659                        (volatile s64)ch->w_remote_GP.put &&
 660                        !((volatile u32)ch->flags & XPC_C_DISCONNECTING)) {
 661                         xpc_deliver_msg(ch);
 662                 }
 663
 664                 if (atomic_inc_return(&ch->kthreads_idle) >
 665                     ch->kthreads_idle_limit) {
 666                         /* too many idle kthreads on this channel */
 667                         atomic_dec(&ch->kthreads_idle);
 668                         break;
 669                 }
 670
 671                 dev_dbg(xpc_chan, "idle kthread calling "
 672                         "wait_event_interruptible_exclusive()\n");
 673
 674                 (void)wait_event_interruptible_exclusive(ch->idle_wq,
 675                                                          ((volatile s64)ch->
 676                                                           w_local_GP.get <
 677                                                           (volatile s64)ch->
 678                                                           w_remote_GP.put ||
 679                                                           ((volatile u32)ch->
 680                                                            flags &
 681                                                            XPC_C_DISCONNECTING)));
 682
 683                 atomic_dec(&ch->kthreads_idle);
 684
 685         } while (!((volatile u32)ch->flags & XPC_C_DISCONNECTING));
 686 }
 687
 688 static int
 689 xpc_daemonize_kthread(void *args)
 690 {
 691         partid_t partid = XPC_UNPACK_ARG1(args);
 692         u16 ch_number = XPC_UNPACK_ARG2(args);
 693         struct xpc_partition *part = &xpc_partitions[partid];
 694         struct xpc_channel *ch;
 695         int n_needed;
 696         unsigned long irq_flags;
 697
 698         daemonize("xpc%02dc%d", partid, ch_number);
 699
 700         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
 701                 partid, ch_number);
 702
 703         ch = &part->channels[ch_number];
 704
 705         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 706
 707                 /* let registerer know that connection has been established */
 708
 709                 spin_lock_irqsave(&ch->lock, irq_flags);
 710                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
 711                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
 712                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 713
 714                         xpc_connected_callout(ch);
 715
 716                         spin_lock_irqsave(&ch->lock, irq_flags);
 717                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
 718                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 719
 720                         /*
 721                          * It is possible that while the callout was being
 722                          * made that the remote partition sent some messages.
 723                          * If that is the case, we may need to activate
 724                          * additional kthreads to help deliver them. We only
 725                          * need one less than total #of messages to deliver.
 726                          */
 727                         n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
 728                         if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING)) {
 729                                 xpc_activate_kthreads(ch, n_needed);
 730                         }
 731                 } else {
 732                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 733                 }
 734
 735                 xpc_kthread_waitmsgs(part, ch);
 736         }
 737
 738         /* let registerer know that connection is disconnecting */
 739
 740         spin_lock_irqsave(&ch->lock, irq_flags);
 741         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 742             !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 743                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
 744                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 745
 746                 xpc_disconnect_callout(ch, xpcDisconnecting);
 747
 748                 spin_lock_irqsave(&ch->lock, irq_flags);
 749                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
 750         }
 751         spin_unlock_irqrestore(&ch->lock, irq_flags);
 752
 753         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
 754                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
 755                         xpc_mark_partition_disengaged(part);
 756                         xpc_IPI_send_disengage(part);
 757                 }
 758         }
 759
 760         xpc_msgqueue_deref(ch);
 761
 762         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 763                 partid, ch_number);
 764
 765         xpc_part_deref(part);
 766         return 0;
 767 }
 768
 769 /*
 770  * For each partition that XPC has established communications with, there is
 771  * a minimum of one kernel thread assigned to perform any operation that
 772  * may potentially sleep or block (basically the callouts to the asynchronous
 773  * functions registered via xpc_connect()).
 774  *
 775  * Additional kthreads are created and destroyed by XPC as the workload
 776  * demands.
 777  *
 778  * A kthread is assigned to one of the active channels that exists for a given
 779  * partition.
 780  */
 781 void
 782 xpc_create_kthreads(struct xpc_channel *ch, int needed,
 783                     int ignore_disconnecting)
 784 {
 785         unsigned long irq_flags;
 786         pid_t pid;
 787         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
 788         struct xpc_partition *part = &xpc_partitions[ch->partid];
 789
 790         while (needed-- > 0) {
 791
 792                 /*
 793                  * The following is done on behalf of the newly created
 794                  * kthread. That kthread is responsible for doing the
 795                  * counterpart to the following before it exits.
 796                  */
 797                 if (ignore_disconnecting) {
 798                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
 799                                 /* kthreads assigned had gone to zero */
 800                                 BUG_ON(!(ch->flags &
 801                                          XPC_C_DISCONNECTINGCALLOUT_MADE));
 802                                 break;
 803                         }
 804
 805                 } else if (ch->flags & XPC_C_DISCONNECTING) {
 806                         break;
 807
 808                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1) {
 809                         if (atomic_inc_return(&part->nchannels_engaged) == 1)
 810                                 xpc_mark_partition_engaged(part);
 811                 }
 812                 (void)xpc_part_ref(part);
 813                 xpc_msgqueue_ref(ch);
 814
 815                 pid = kernel_thread(xpc_daemonize_kthread, (void *)args, 0);
 816                 if (pid < 0) {
 817                         /* the fork failed */
 818
 819                         /*
 820                          * NOTE: if (ignore_disconnecting &&
 821                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
 822                          * then we'll deadlock if all other kthreads assigned
 823                          * to this channel are blocked in the channel's
 824                          * registerer, because the only thing that will unblock
 825                          * them is the xpcDisconnecting callout that this
 826                          * failed kernel_thread would have made.
 827                          */
 828
 829                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 830                             atomic_dec_return(&part->nchannels_engaged) == 0) {
 831                                 xpc_mark_partition_disengaged(part);
 832                                 xpc_IPI_send_disengage(part);
 833                         }
 834                         xpc_msgqueue_deref(ch);
 835                         xpc_part_deref(part);
 836
 837                         if (atomic_read(&ch->kthreads_assigned) <
 838                             ch->kthreads_idle_limit) {
 839                                 /*
 840                                  * Flag this as an error only if we have an
 841                                  * insufficient #of kthreads for the channel
 842                                  * to function.
 843                                  */
 844                                 spin_lock_irqsave(&ch->lock, irq_flags);
 845                                 XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
 846                                                        &irq_flags);
 847                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 848                         }
 849                         break;
 850                 }
 851
 852                 ch->kthreads_created++; // >>> temporary debug only!!!
 853         }
 854 }
 855
 856 void
 857 xpc_disconnect_wait(int ch_number)
 858 {
 859         unsigned long irq_flags;
 860         partid_t partid;
 861         struct xpc_partition *part;
 862         struct xpc_channel *ch;
 863         int wakeup_channel_mgr;
 864
 865         /* now wait for all callouts to the caller's function to cease */
 866         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 867                 part = &xpc_partitions[partid];
 868
 869                 if (!xpc_part_ref(part)) {
 870                         continue;
 871                 }
 872
 873                 ch = &part->channels[ch_number];
 874
 875                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
 876                         xpc_part_deref(part);
 877                         continue;
 878                 }
 879
 880                 wait_for_completion(&ch->wdisconnect_wait);
 881
 882                 spin_lock_irqsave(&ch->lock, irq_flags);
 883                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 884                 wakeup_channel_mgr = 0;
 885
 886                 if (ch->delayed_IPI_flags) {
 887                         if (part->act_state != XPC_P_DEACTIVATING) {
 888                                 spin_lock(&part->IPI_lock);
 889                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 890                                                   ch->number,
 891                                                   ch->delayed_IPI_flags);
 892                                 spin_unlock(&part->IPI_lock);
 893                                 wakeup_channel_mgr = 1;
 894                         }
 895                         ch->delayed_IPI_flags = 0;
 896                 }
 897
 898                 ch->flags &= ~XPC_C_WDISCONNECT;
 899                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 900
 901                 if (wakeup_channel_mgr) {
 902                         xpc_wakeup_channel_mgr(part);
 903                 }
 904
 905                 xpc_part_deref(part);
 906         }
 907 }
 908
 909 static void
 910 xpc_do_exit(enum xpc_retval reason)
 911 {
 912         partid_t partid;
 913         int active_part_count, printed_waiting_msg = 0;
 914         struct xpc_partition *part;
 915         unsigned long printmsg_time, disengage_request_timeout = 0;
 916
 917         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 918         DBUG_ON(xpc_exiting == 1);
 919
 920         /*
 921          * Let the heartbeat checker thread and the discovery thread
 922          * (if one is running) know that they should exit. Also wake up
 923          * the heartbeat checker thread in case it's sleeping.
 924          */
 925         xpc_exiting = 1;
 926         wake_up_interruptible(&xpc_act_IRQ_wq);
 927
 928         /* ignore all incoming interrupts */
 929         free_irq(SGI_XPC_ACTIVATE, NULL);
 930
 931         /* wait for the discovery thread to exit */
 932         wait_for_completion(&xpc_discovery_exited);
 933
 934         /* wait for the heartbeat checker thread to exit */
 935         wait_for_completion(&xpc_hb_checker_exited);
 936
 937         /* sleep for a 1/3 of a second or so */
 938         (void)msleep_interruptible(300);
 939
 940         /* wait for all partitions to become inactive */
 941
 942         printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 943         xpc_disengage_request_timedout = 0;
 944
 945         do {
 946                 active_part_count = 0;
 947
 948                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 949                         part = &xpc_partitions[partid];
 950
 951                         if (xpc_partition_disengaged(part) &&
 952                             part->act_state == XPC_P_INACTIVE) {
 953                                 continue;
 954                         }
 955
 956                         active_part_count++;
 957
 958                         XPC_DEACTIVATE_PARTITION(part, reason);
 959
 960                         if (part->disengage_request_timeout >
 961                             disengage_request_timeout) {
 962                                 disengage_request_timeout =
 963                                     part->disengage_request_timeout;
 964                         }
 965                 }
 966
 967                 if (xpc_partition_engaged(-1UL)) {
 968                         if (time_after(jiffies, printmsg_time)) {
 969                                 dev_info(xpc_part, "waiting for remote "
 970                                          "partitions to disengage, timeout in "
 971                                          "%ld seconds\n",
 972                                          (disengage_request_timeout - jiffies)
 973                                          / HZ);
 974                                 printmsg_time = jiffies +
 975                                     (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 976                                 printed_waiting_msg = 1;
 977                         }
 978
 979                 } else if (active_part_count > 0) {
 980                         if (printed_waiting_msg) {
 981                                 dev_info(xpc_part, "waiting for local partition"
 982                                          " to disengage\n");
 983                                 printed_waiting_msg = 0;
 984                         }
 985
 986                 } else {
 987                         if (!xpc_disengage_request_timedout) {
 988                                 dev_info(xpc_part, "all partitions have "
 989                                          "disengaged\n");
 990                         }
 991                         break;
 992                 }
 993
 994                 /* sleep for a 1/3 of a second or so */
 995                 (void)msleep_interruptible(300);
 996
 997         } while (1);
 998
 999         DBUG_ON(xpc_partition_engaged(-1UL));
1000
1001         /* indicate to others that our reserved page is uninitialized */
1002         xpc_rsvd_page->vars_pa = 0;
1003
1004         /* now it's time to eliminate our heartbeat */
1005         del_timer_sync(&xpc_hb_timer);
1006         DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
1007
1008         if (reason == xpcUnloading) {
1009                 /* take ourselves off of the reboot_notifier_list */
1010                 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1011
1012                 /* take ourselves off of the die_notifier list */
1013                 (void)unregister_die_notifier(&xpc_die_notifier);
1014         }
1015
1016         /* close down protections for IPI operations */
1017         xpc_restrict_IPI_ops();
1018
1019         /* clear the interface to XPC's functions */
1020         xpc_clear_interface();
1021
1022         if (xpc_sysctl) {
1023                 unregister_sysctl_table(xpc_sysctl);
1024         }
1025
1026         kfree(xpc_remote_copy_buffer_base);
1027 }
1028
1029 /*
1030  * This function is called when the system is being rebooted.
1031  */
1032 static int
1033 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1034 {
1035         enum xpc_retval reason;
1036
1037         switch (event) {
1038         case SYS_RESTART:
1039                 reason = xpcSystemReboot;
1040                 break;
1041         case SYS_HALT:
1042                 reason = xpcSystemHalt;
1043                 break;
1044         case SYS_POWER_OFF:
1045                 reason = xpcSystemPoweroff;
1046                 break;
1047         default:
1048                 reason = xpcSystemGoingDown;
1049         }
1050
1051         xpc_do_exit(reason);
1052         return NOTIFY_DONE;
1053 }
1054
1055 /*
1056  * Notify other partitions to disengage from all references to our memory.
1057  */
1058 static void
1059 xpc_die_disengage(void)
1060 {
1061         struct xpc_partition *part;
1062         partid_t partid;
1063         unsigned long engaged;
1064         long time, printmsg_time, disengage_request_timeout;
1065
1066         /* keep xpc_hb_checker thread from doing anything (just in case) */
1067         xpc_exiting = 1;
1068
1069         xpc_vars->heartbeating_to_mask = 0;     /* indicate we're deactivated */
1070
1071         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1072                 part = &xpc_partitions[partid];
1073
1074                 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
1075
1076                         /* just in case it was left set by an earlier XPC */
1077                         xpc_clear_partition_engaged(1UL << partid);
1078                         continue;
1079                 }
1080
1081                 if (xpc_partition_engaged(1UL << partid) ||
1082                     part->act_state != XPC_P_INACTIVE) {
1083                         xpc_request_partition_disengage(part);
1084                         xpc_mark_partition_disengaged(part);
1085                         xpc_IPI_send_disengage(part);
1086                 }
1087         }
1088
1089         time = rtc_time();
1090         printmsg_time = time +
1091             (XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
1092         disengage_request_timeout = time +
1093             (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1094
1095         /* wait for all other partitions to disengage from us */
1096
1097         while (1) {
1098                 engaged = xpc_partition_engaged(-1UL);
1099                 if (!engaged) {
1100                         dev_info(xpc_part, "all partitions have disengaged\n");
1101                         break;
1102                 }
1103
1104                 time = rtc_time();
1105                 if (time >= disengage_request_timeout) {
1106                         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1107                                 if (engaged & (1UL << partid)) {
1108                                         dev_info(xpc_part, "disengage from "
1109                                                  "remote partition %d timed "
1110                                                  "out\n", partid);
1111                                 }
1112                         }
1113                         break;
1114                 }
1115
1116                 if (time >= printmsg_time) {
1117                         dev_info(xpc_part, "waiting for remote partitions to "
1118                                  "disengage, timeout in %ld seconds\n",
1119                                  (disengage_request_timeout - time) /
1120                                  sn_rtc_cycles_per_second);
1121                         printmsg_time = time +
1122                             (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1123                              sn_rtc_cycles_per_second);
1124                 }
1125         }
1126 }
1127
1128 /*
1129  * This function is called when the system is being restarted or halted due
1130  * to some sort of system failure. If this is the case we need to notify the
1131  * other partitions to disengage from all references to our memory.
1132  * This function can also be called when our heartbeater could be offlined
1133  * for a time. In this case we need to notify other partitions to not worry
1134  * about the lack of a heartbeat.
1135  */
1136 static int
1137 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1138 {
1139         switch (event) {
1140         case DIE_MACHINE_RESTART:
1141         case DIE_MACHINE_HALT:
1142                 xpc_die_disengage();
1143                 break;
1144
1145         case DIE_KDEBUG_ENTER:
1146                 /* Should lack of heartbeat be ignored by other partitions? */
1147                 if (!xpc_kdebug_ignore) {
1148                         break;
1149                 }
1150                 /* fall through */
1151         case DIE_MCA_MONARCH_ENTER:
1152         case DIE_INIT_MONARCH_ENTER:
1153                 xpc_vars->heartbeat++;
1154                 xpc_vars->heartbeat_offline = 1;
1155                 break;
1156
1157         case DIE_KDEBUG_LEAVE:
1158                 /* Is lack of heartbeat being ignored by other partitions? */
1159                 if (!xpc_kdebug_ignore) {
1160                         break;
1161                 }
1162                 /* fall through */
1163         case DIE_MCA_MONARCH_LEAVE:
1164         case DIE_INIT_MONARCH_LEAVE:
1165                 xpc_vars->heartbeat++;
1166                 xpc_vars->heartbeat_offline = 0;
1167                 break;
1168         }
1169
1170         return NOTIFY_DONE;
1171 }
1172
1173 int __init
1174 xpc_init(void)
1175 {
1176         int ret;
1177         partid_t partid;
1178         struct xpc_partition *part;
1179         pid_t pid;
1180         size_t buf_size;
1181
1182         if (!ia64_platform_is("sn2")) {
1183                 return -ENODEV;
1184         }
1185
1186         buf_size = max(XPC_RP_VARS_SIZE,
1187                        XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES);
1188         xpc_remote_copy_buffer = xpc_kmalloc_cacheline_aligned(buf_size,
1189                                                                GFP_KERNEL,
1190                                                                &xpc_remote_copy_buffer_base);
1191         if (xpc_remote_copy_buffer == NULL)
1192                 return -ENOMEM;
1193
1194         snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1195         snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1196
1197         xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1198
1199         /*
1200          * The first few fields of each entry of xpc_partitions[] need to
1201          * be initialized now so that calls to xpc_connect() and
1202          * xpc_disconnect() can be made prior to the activation of any remote
1203          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1204          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1205          * PARTITION HAS BEEN ACTIVATED.
1206          */
1207         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1208                 part = &xpc_partitions[partid];
1209
1210                 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
1211
1212                 part->act_IRQ_rcvd = 0;
1213                 spin_lock_init(&part->act_lock);
1214                 part->act_state = XPC_P_INACTIVE;
1215                 XPC_SET_REASON(part, 0, 0);
1216
1217                 init_timer(&part->disengage_request_timer);
1218                 part->disengage_request_timer.function =
1219                     xpc_timeout_partition_disengage_request;
1220                 part->disengage_request_timer.data = (unsigned long)part;
1221
1222                 part->setup_state = XPC_P_UNSET;
1223                 init_waitqueue_head(&part->teardown_wq);
1224                 atomic_set(&part->references, 0);
1225         }
1226
1227         /*
1228          * Open up protections for IPI operations (and AMO operations on
1229          * Shub 1.1 systems).
1230          */
1231         xpc_allow_IPI_ops();
1232
1233         /*
1234          * Interrupts being processed will increment this atomic variable and
1235          * awaken the heartbeat thread which will process the interrupts.
1236          */
1237         atomic_set(&xpc_act_IRQ_rcvd, 0);
1238
1239         /*
1240          * This is safe to do before the xpc_hb_checker thread has started
1241          * because the handler releases a wait queue.  If an interrupt is
1242          * received before the thread is waiting, it will not go to sleep,
1243          * but rather immediately process the interrupt.
1244          */
1245         ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1246                           "xpc hb", NULL);
1247         if (ret != 0) {
1248                 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1249                         "errno=%d\n", -ret);
1250
1251                 xpc_restrict_IPI_ops();
1252
1253                 if (xpc_sysctl) {
1254                         unregister_sysctl_table(xpc_sysctl);
1255                 }
1256
1257                 kfree(xpc_remote_copy_buffer_base);
1258                 return -EBUSY;
1259         }
1260
1261         /*
1262          * Fill the partition reserved page with the information needed by
1263          * other partitions to discover we are alive and establish initial
1264          * communications.
1265          */
1266         xpc_rsvd_page = xpc_rsvd_page_init();
1267         if (xpc_rsvd_page == NULL) {
1268                 dev_err(xpc_part, "could not setup our reserved page\n");
1269
1270                 free_irq(SGI_XPC_ACTIVATE, NULL);
1271                 xpc_restrict_IPI_ops();
1272
1273                 if (xpc_sysctl) {
1274                         unregister_sysctl_table(xpc_sysctl);
1275                 }
1276
1277                 kfree(xpc_remote_copy_buffer_base);
1278                 return -EBUSY;
1279         }
1280
1281         /* add ourselves to the reboot_notifier_list */
1282         ret = register_reboot_notifier(&xpc_reboot_notifier);
1283         if (ret != 0) {
1284                 dev_warn(xpc_part, "can't register reboot notifier\n");
1285         }
1286
1287         /* add ourselves to the die_notifier list */
1288         ret = register_die_notifier(&xpc_die_notifier);
1289         if (ret != 0) {
1290                 dev_warn(xpc_part, "can't register die notifier\n");
1291         }
1292
1293         init_timer(&xpc_hb_timer);
1294         xpc_hb_timer.function = xpc_hb_beater;
1295
1296         /*
1297          * The real work-horse behind xpc.  This processes incoming
1298          * interrupts and monitors remote heartbeats.
1299          */
1300         pid = kernel_thread(xpc_hb_checker, NULL, 0);
1301         if (pid < 0) {
1302                 dev_err(xpc_part, "failed while forking hb check thread\n");
1303
1304                 /* indicate to others that our reserved page is uninitialized */
1305                 xpc_rsvd_page->vars_pa = 0;
1306
1307                 /* take ourselves off of the reboot_notifier_list */
1308                 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1309
1310                 /* take ourselves off of the die_notifier list */
1311                 (void)unregister_die_notifier(&xpc_die_notifier);
1312
1313                 del_timer_sync(&xpc_hb_timer);
1314                 free_irq(SGI_XPC_ACTIVATE, NULL);
1315                 xpc_restrict_IPI_ops();
1316
1317                 if (xpc_sysctl) {
1318                         unregister_sysctl_table(xpc_sysctl);
1319                 }
1320
1321                 kfree(xpc_remote_copy_buffer_base);
1322                 return -EBUSY;
1323         }
1324
1325         /*
1326          * Startup a thread that will attempt to discover other partitions to
1327          * activate based on info provided by SAL. This new thread is short
1328          * lived and will exit once discovery is complete.
1329          */
1330         pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
1331         if (pid < 0) {
1332                 dev_err(xpc_part, "failed while forking discovery thread\n");
1333
1334                 /* mark this new thread as a non-starter */
1335                 complete(&xpc_discovery_exited);
1336
1337                 xpc_do_exit(xpcUnloading);
1338                 return -EBUSY;
1339         }
1340
1341         /* set the interface to point at XPC's functions */
1342         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1343                           xpc_initiate_allocate, xpc_initiate_send,
1344                           xpc_initiate_send_notify, xpc_initiate_received,
1345                           xpc_initiate_partid_to_nasids);
1346
1347         return 0;
1348 }
1349
1350 module_init(xpc_init);
1351
1352 void __exit
1353 xpc_exit(void)
1354 {
1355         xpc_do_exit(xpcUnloading);
1356 }
1357
1358 module_exit(xpc_exit);
1359
1360 MODULE_AUTHOR("Silicon Graphics, Inc.");
1361 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1362 MODULE_LICENSE("GPL");
1363
1364 module_param(xpc_hb_interval, int, 0);
1365 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1366                  "heartbeat increments.");
1367
1368 module_param(xpc_hb_check_interval, int, 0);
1369 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1370                  "heartbeat checks.");
1371
1372 module_param(xpc_disengage_request_timelimit, int, 0);
1373 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1374                  "for disengage request to complete.");
1375
1376 module_param(xpc_kdebug_ignore, int, 0);
1377 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1378                  "other partitions when dropping into kdebug.");