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) 2004-2009 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 *	  . Currently on sn2, we have no way to determine which nasid an IRQ
  29 *	    came from. Thus, xpc_send_IRQ_sn2() does a remote amo write
  30 *	    followed by an IPI. The amo indicates where data is to be pulled
  31 *	    from, so after the IPI arrives, the remote partition checks the amo
  32 *	    word. The IPI can actually arrive before the amo however, so other
  33 *	    code must periodically check for this case. Also, remote amo
  34 *	    operations do not reliably time out. Thus we do a remote PIO read
  35 *	    solely to know whether the remote partition is down and whether we
  36 *	    should stop sending IPIs to it. This remote PIO read operation is
  37 *	    set up in a special nofault region so SAL knows to ignore (and
  38 *	    cleanup) any errors due to the remote amo write, PIO read, and/or
  39 *	    PIO 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/module.h>
  47#include <linux/slab.h>
  48#include <linux/sysctl.h>
  49#include <linux/device.h>
  50#include <linux/delay.h>
  51#include <linux/reboot.h>
  52#include <linux/kdebug.h>
  53#include <linux/kthread.h>
  54#include "xpc.h"
  55
  56#ifdef CONFIG_X86_64
  57#include <asm/traps.h>
  58#endif
  59
  60/* define two XPC debug device structures to be used with dev_dbg() et al */
  61
  62struct device_driver xpc_dbg_name = {
  63	.name = "xpc"
  64};
  65
  66struct device xpc_part_dbg_subname = {
  67	.init_name = "",	/* set to "part" at xpc_init() time */
  68	.driver = &xpc_dbg_name
  69};
  70
  71struct device xpc_chan_dbg_subname = {
  72	.init_name = "",	/* set to "chan" at xpc_init() time */
  73	.driver = &xpc_dbg_name
  74};
  75
  76struct device *xpc_part = &xpc_part_dbg_subname;
  77struct device *xpc_chan = &xpc_chan_dbg_subname;
  78
  79static int xpc_kdebug_ignore;
  80
  81/* systune related variables for /proc/sys directories */
  82
  83static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
  84static int xpc_hb_min_interval = 1;
  85static int xpc_hb_max_interval = 10;
  86
  87static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
  88static int xpc_hb_check_min_interval = 10;
  89static int xpc_hb_check_max_interval = 120;
  90
  91int xpc_disengage_timelimit = XPC_DISENGAGE_DEFAULT_TIMELIMIT;
  92static int xpc_disengage_min_timelimit;	/* = 0 */
  93static int xpc_disengage_max_timelimit = 120;
  94
  95static struct ctl_table xpc_sys_xpc_hb_dir[] = {
  96	{
  97	 .procname = "hb_interval",
  98	 .data = &xpc_hb_interval,
  99	 .maxlen = sizeof(int),
 100	 .mode = 0644,
 101	 .proc_handler = proc_dointvec_minmax,
 102	 .extra1 = &xpc_hb_min_interval,
 103	 .extra2 = &xpc_hb_max_interval},
 104	{
 105	 .procname = "hb_check_interval",
 106	 .data = &xpc_hb_check_interval,
 107	 .maxlen = sizeof(int),
 108	 .mode = 0644,
 109	 .proc_handler = proc_dointvec_minmax,
 110	 .extra1 = &xpc_hb_check_min_interval,
 111	 .extra2 = &xpc_hb_check_max_interval},
 112	{}
 113};
 114static struct ctl_table xpc_sys_xpc_dir[] = {
 115	{
 116	 .procname = "hb",
 117	 .mode = 0555,
 118	 .child = xpc_sys_xpc_hb_dir},
 119	{
 120	 .procname = "disengage_timelimit",
 121	 .data = &xpc_disengage_timelimit,
 122	 .maxlen = sizeof(int),
 123	 .mode = 0644,
 124	 .proc_handler = proc_dointvec_minmax,
 125	 .extra1 = &xpc_disengage_min_timelimit,
 126	 .extra2 = &xpc_disengage_max_timelimit},
 127	{}
 128};
 129static struct ctl_table xpc_sys_dir[] = {
 130	{
 131	 .procname = "xpc",
 132	 .mode = 0555,
 133	 .child = xpc_sys_xpc_dir},
 134	{}
 135};
 136static struct ctl_table_header *xpc_sysctl;
 137
 138/* non-zero if any remote partition disengage was timed out */
 139int xpc_disengage_timedout;
 140
 141/* #of activate IRQs received and not yet processed */
 142int xpc_activate_IRQ_rcvd;
 143DEFINE_SPINLOCK(xpc_activate_IRQ_rcvd_lock);
 144
 145/* IRQ handler notifies this wait queue on receipt of an IRQ */
 146DECLARE_WAIT_QUEUE_HEAD(xpc_activate_IRQ_wq);
 147
 148static unsigned long xpc_hb_check_timeout;
 149static struct timer_list xpc_hb_timer;
 150
 151/* notification that the xpc_hb_checker thread has exited */
 152static DECLARE_COMPLETION(xpc_hb_checker_exited);
 153
 154/* notification that the xpc_discovery thread has exited */
 155static DECLARE_COMPLETION(xpc_discovery_exited);
 156
 157static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
 158
 159static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
 160static struct notifier_block xpc_reboot_notifier = {
 161	.notifier_call = xpc_system_reboot,
 162};
 163
 164static int xpc_system_die(struct notifier_block *, unsigned long, void *);
 165static struct notifier_block xpc_die_notifier = {
 166	.notifier_call = xpc_system_die,
 167};
 168
 169struct xpc_arch_operations xpc_arch_ops;
 170
 171/*
 172 * Timer function to enforce the timelimit on the partition disengage.
 173 */
 174static void
 175xpc_timeout_partition_disengage(struct timer_list *t)
 176{
 177	struct xpc_partition *part = from_timer(part, t, disengage_timer);
 178
 179	DBUG_ON(time_is_after_jiffies(part->disengage_timeout));
 180
 181	(void)xpc_partition_disengaged(part);
 182
 183	DBUG_ON(part->disengage_timeout != 0);
 184	DBUG_ON(xpc_arch_ops.partition_engaged(XPC_PARTID(part)));
 185}
 186
 187/*
 188 * Timer to produce the heartbeat.  The timer structures function is
 189 * already set when this is initially called.  A tunable is used to
 190 * specify when the next timeout should occur.
 191 */
 192static void
 193xpc_hb_beater(struct timer_list *unused)
 194{
 195	xpc_arch_ops.increment_heartbeat();
 196
 197	if (time_is_before_eq_jiffies(xpc_hb_check_timeout))
 198		wake_up_interruptible(&xpc_activate_IRQ_wq);
 199
 200	xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
 201	add_timer(&xpc_hb_timer);
 202}
 203
 204static void
 205xpc_start_hb_beater(void)
 206{
 207	xpc_arch_ops.heartbeat_init();
 208	timer_setup(&xpc_hb_timer, xpc_hb_beater, 0);
 209	xpc_hb_beater(0);
 210}
 211
 212static void
 213xpc_stop_hb_beater(void)
 214{
 215	del_timer_sync(&xpc_hb_timer);
 216	xpc_arch_ops.heartbeat_exit();
 217}
 218
 219/*
 220 * At periodic intervals, scan through all active partitions and ensure
 221 * their heartbeat is still active.  If not, the partition is deactivated.
 222 */
 223static void
 224xpc_check_remote_hb(void)
 225{
 226	struct xpc_partition *part;
 227	short partid;
 228	enum xp_retval ret;
 229
 230	for (partid = 0; partid < xp_max_npartitions; partid++) {
 231
 232		if (xpc_exiting)
 233			break;
 234
 235		if (partid == xp_partition_id)
 236			continue;
 237
 238		part = &xpc_partitions[partid];
 239
 240		if (part->act_state == XPC_P_AS_INACTIVE ||
 241		    part->act_state == XPC_P_AS_DEACTIVATING) {
 242			continue;
 243		}
 244
 245		ret = xpc_arch_ops.get_remote_heartbeat(part);
 246		if (ret != xpSuccess)
 247			XPC_DEACTIVATE_PARTITION(part, ret);
 248	}
 249}
 250
 251/*
 252 * This thread is responsible for nearly all of the partition
 253 * activation/deactivation.
 254 */
 255static int
 256xpc_hb_checker(void *ignore)
 257{
 258	int force_IRQ = 0;
 259
 260	/* this thread was marked active by xpc_hb_init() */
 261
 262	set_cpus_allowed_ptr(current, cpumask_of(XPC_HB_CHECK_CPU));
 263
 264	/* set our heartbeating to other partitions into motion */
 265	xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
 266	xpc_start_hb_beater();
 267
 268	while (!xpc_exiting) {
 269
 270		dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
 271			"been received\n",
 272			(int)(xpc_hb_check_timeout - jiffies),
 273			xpc_activate_IRQ_rcvd);
 274
 275		/* checking of remote heartbeats is skewed by IRQ handling */
 276		if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) {
 277			xpc_hb_check_timeout = jiffies +
 278			    (xpc_hb_check_interval * HZ);
 279
 280			dev_dbg(xpc_part, "checking remote heartbeats\n");
 281			xpc_check_remote_hb();
 282		}
 283
 284		/* check for outstanding IRQs */
 285		if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
 286			force_IRQ = 0;
 287			dev_dbg(xpc_part, "processing activate IRQs "
 288				"received\n");
 289			xpc_arch_ops.process_activate_IRQ_rcvd();
 290		}
 291
 292		/* wait for IRQ or timeout */
 293		(void)wait_event_interruptible(xpc_activate_IRQ_wq,
 294					       (time_is_before_eq_jiffies(
 295						xpc_hb_check_timeout) ||
 296						xpc_activate_IRQ_rcvd > 0 ||
 297						xpc_exiting));
 298	}
 299
 300	xpc_stop_hb_beater();
 301
 302	dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 303
 304	/* mark this thread as having exited */
 305	complete(&xpc_hb_checker_exited);
 306	return 0;
 307}
 308
 309/*
 310 * This thread will attempt to discover other partitions to activate
 311 * based on info provided by SAL. This new thread is short lived and
 312 * will exit once discovery is complete.
 313 */
 314static int
 315xpc_initiate_discovery(void *ignore)
 316{
 317	xpc_discovery();
 318
 319	dev_dbg(xpc_part, "discovery thread is exiting\n");
 320
 321	/* mark this thread as having exited */
 322	complete(&xpc_discovery_exited);
 323	return 0;
 324}
 325
 326/*
 327 * The first kthread assigned to a newly activated partition is the one
 328 * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
 329 * that kthread until the partition is brought down, at which time that kthread
 330 * returns back to XPC HB. (The return of that kthread will signify to XPC HB
 331 * that XPC has dismantled all communication infrastructure for the associated
 332 * partition.) This kthread becomes the channel manager for that partition.
 333 *
 334 * Each active partition has a channel manager, who, besides connecting and
 335 * disconnecting channels, will ensure that each of the partition's connected
 336 * channels has the required number of assigned kthreads to get the work done.
 337 */
 338static void
 339xpc_channel_mgr(struct xpc_partition *part)
 340{
 341	while (part->act_state != XPC_P_AS_DEACTIVATING ||
 342	       atomic_read(&part->nchannels_active) > 0 ||
 343	       !xpc_partition_disengaged(part)) {
 344
 345		xpc_process_sent_chctl_flags(part);
 346
 347		/*
 348		 * Wait until we've been requested to activate kthreads or
 349		 * all of the channel's message queues have been torn down or
 350		 * a signal is pending.
 351		 *
 352		 * The channel_mgr_requests is set to 1 after being awakened,
 353		 * This is done to prevent the channel mgr from making one pass
 354		 * through the loop for each request, since he will
 355		 * be servicing all the requests in one pass. The reason it's
 356		 * set to 1 instead of 0 is so that other kthreads will know
 357		 * that the channel mgr is running and won't bother trying to
 358		 * wake him up.
 359		 */
 360		atomic_dec(&part->channel_mgr_requests);
 361		(void)wait_event_interruptible(part->channel_mgr_wq,
 362				(atomic_read(&part->channel_mgr_requests) > 0 ||
 363				 part->chctl.all_flags != 0 ||
 364				 (part->act_state == XPC_P_AS_DEACTIVATING &&
 365				 atomic_read(&part->nchannels_active) == 0 &&
 366				 xpc_partition_disengaged(part))));
 367		atomic_set(&part->channel_mgr_requests, 1);
 368	}
 369}
 370
 371/*
 372 * Guarantee that the kzalloc'd memory is cacheline aligned.
 373 */
 374void *
 375xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
 376{
 377	/* see if kzalloc will give us cachline aligned memory by default */
 378	*base = kzalloc(size, flags);
 379	if (*base == NULL)
 380		return NULL;
 381
 382	if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
 383		return *base;
 384
 385	kfree(*base);
 386
 387	/* nope, we'll have to do it ourselves */
 388	*base = kzalloc(size + L1_CACHE_BYTES, flags);
 389	if (*base == NULL)
 390		return NULL;
 391
 392	return (void *)L1_CACHE_ALIGN((u64)*base);
 393}
 394
 395/*
 396 * Setup the channel structures necessary to support XPartition Communication
 397 * between the specified remote partition and the local one.
 398 */
 399static enum xp_retval
 400xpc_setup_ch_structures(struct xpc_partition *part)
 401{
 402	enum xp_retval ret;
 403	int ch_number;
 404	struct xpc_channel *ch;
 405	short partid = XPC_PARTID(part);
 406
 407	/*
 408	 * Allocate all of the channel structures as a contiguous chunk of
 409	 * memory.
 410	 */
 411	DBUG_ON(part->channels != NULL);
 412	part->channels = kcalloc(XPC_MAX_NCHANNELS,
 413				 sizeof(struct xpc_channel),
 414				 GFP_KERNEL);
 415	if (part->channels == NULL) {
 416		dev_err(xpc_chan, "can't get memory for channels\n");
 417		return xpNoMemory;
 418	}
 419
 420	/* allocate the remote open and close args */
 421
 422	part->remote_openclose_args =
 423	    xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
 424					  GFP_KERNEL, &part->
 425					  remote_openclose_args_base);
 426	if (part->remote_openclose_args == NULL) {
 427		dev_err(xpc_chan, "can't get memory for remote connect args\n");
 428		ret = xpNoMemory;
 429		goto out_1;
 430	}
 431
 432	part->chctl.all_flags = 0;
 433	spin_lock_init(&part->chctl_lock);
 434
 435	atomic_set(&part->channel_mgr_requests, 1);
 436	init_waitqueue_head(&part->channel_mgr_wq);
 437
 438	part->nchannels = XPC_MAX_NCHANNELS;
 439
 440	atomic_set(&part->nchannels_active, 0);
 441	atomic_set(&part->nchannels_engaged, 0);
 442
 443	for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 444		ch = &part->channels[ch_number];
 445
 446		ch->partid = partid;
 447		ch->number = ch_number;
 448		ch->flags = XPC_C_DISCONNECTED;
 449
 450		atomic_set(&ch->kthreads_assigned, 0);
 451		atomic_set(&ch->kthreads_idle, 0);
 452		atomic_set(&ch->kthreads_active, 0);
 453
 454		atomic_set(&ch->references, 0);
 455		atomic_set(&ch->n_to_notify, 0);
 456
 457		spin_lock_init(&ch->lock);
 458		init_completion(&ch->wdisconnect_wait);
 459
 460		atomic_set(&ch->n_on_msg_allocate_wq, 0);
 461		init_waitqueue_head(&ch->msg_allocate_wq);
 462		init_waitqueue_head(&ch->idle_wq);
 463	}
 464
 465	ret = xpc_arch_ops.setup_ch_structures(part);
 466	if (ret != xpSuccess)
 467		goto out_2;
 468
 469	/*
 470	 * With the setting of the partition setup_state to XPC_P_SS_SETUP,
 471	 * we're declaring that this partition is ready to go.
 472	 */
 473	part->setup_state = XPC_P_SS_SETUP;
 474
 475	return xpSuccess;
 476
 477	/* setup of ch structures failed */
 478out_2:
 479	kfree(part->remote_openclose_args_base);
 480	part->remote_openclose_args = NULL;
 481out_1:
 482	kfree(part->channels);
 483	part->channels = NULL;
 484	return ret;
 485}
 486
 487/*
 488 * Teardown the channel structures necessary to support XPartition Communication
 489 * between the specified remote partition and the local one.
 490 */
 491static void
 492xpc_teardown_ch_structures(struct xpc_partition *part)
 493{
 494	DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
 495	DBUG_ON(atomic_read(&part->nchannels_active) != 0);
 496
 497	/*
 498	 * Make this partition inaccessible to local processes by marking it
 499	 * as no longer setup. Then wait before proceeding with the teardown
 500	 * until all existing references cease.
 501	 */
 502	DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
 503	part->setup_state = XPC_P_SS_WTEARDOWN;
 504
 505	wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
 506
 507	/* now we can begin tearing down the infrastructure */
 508
 509	xpc_arch_ops.teardown_ch_structures(part);
 510
 511	kfree(part->remote_openclose_args_base);
 512	part->remote_openclose_args = NULL;
 513	kfree(part->channels);
 514	part->channels = NULL;
 515
 516	part->setup_state = XPC_P_SS_TORNDOWN;
 517}
 518
 519/*
 520 * When XPC HB determines that a partition has come up, it will create a new
 521 * kthread and that kthread will call this function to attempt to set up the
 522 * basic infrastructure used for Cross Partition Communication with the newly
 523 * upped partition.
 524 *
 525 * The kthread that was created by XPC HB and which setup the XPC
 526 * infrastructure will remain assigned to the partition becoming the channel
 527 * manager for that partition until the partition is deactivating, at which
 528 * time the kthread will teardown the XPC infrastructure and then exit.
 529 */
 530static int
 531xpc_activating(void *__partid)
 532{
 533	short partid = (u64)__partid;
 534	struct xpc_partition *part = &xpc_partitions[partid];
 535	unsigned long irq_flags;
 536
 537	DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
 538
 539	spin_lock_irqsave(&part->act_lock, irq_flags);
 540
 541	if (part->act_state == XPC_P_AS_DEACTIVATING) {
 542		part->act_state = XPC_P_AS_INACTIVE;
 543		spin_unlock_irqrestore(&part->act_lock, irq_flags);
 544		part->remote_rp_pa = 0;
 545		return 0;
 546	}
 547
 548	/* indicate the thread is activating */
 549	DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
 550	part->act_state = XPC_P_AS_ACTIVATING;
 551
 552	XPC_SET_REASON(part, 0, 0);
 553	spin_unlock_irqrestore(&part->act_lock, irq_flags);
 554
 555	dev_dbg(xpc_part, "activating partition %d\n", partid);
 556
 557	xpc_arch_ops.allow_hb(partid);
 558
 559	if (xpc_setup_ch_structures(part) == xpSuccess) {
 560		(void)xpc_part_ref(part);	/* this will always succeed */
 561
 562		if (xpc_arch_ops.make_first_contact(part) == xpSuccess) {
 563			xpc_mark_partition_active(part);
 564			xpc_channel_mgr(part);
 565			/* won't return until partition is deactivating */
 566		}
 567
 568		xpc_part_deref(part);
 569		xpc_teardown_ch_structures(part);
 570	}
 571
 572	xpc_arch_ops.disallow_hb(partid);
 573	xpc_mark_partition_inactive(part);
 574
 575	if (part->reason == xpReactivating) {
 576		/* interrupting ourselves results in activating partition */
 577		xpc_arch_ops.request_partition_reactivation(part);
 578	}
 579
 580	return 0;
 581}
 582
 583void
 584xpc_activate_partition(struct xpc_partition *part)
 585{
 586	short partid = XPC_PARTID(part);
 587	unsigned long irq_flags;
 588	struct task_struct *kthread;
 589
 590	spin_lock_irqsave(&part->act_lock, irq_flags);
 591
 592	DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
 593
 594	part->act_state = XPC_P_AS_ACTIVATION_REQ;
 595	XPC_SET_REASON(part, xpCloneKThread, __LINE__);
 596
 597	spin_unlock_irqrestore(&part->act_lock, irq_flags);
 598
 599	kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
 600			      partid);
 601	if (IS_ERR(kthread)) {
 602		spin_lock_irqsave(&part->act_lock, irq_flags);
 603		part->act_state = XPC_P_AS_INACTIVE;
 604		XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
 605		spin_unlock_irqrestore(&part->act_lock, irq_flags);
 606	}
 607}
 608
 609void
 610xpc_activate_kthreads(struct xpc_channel *ch, int needed)
 611{
 612	int idle = atomic_read(&ch->kthreads_idle);
 613	int assigned = atomic_read(&ch->kthreads_assigned);
 614	int wakeup;
 615
 616	DBUG_ON(needed <= 0);
 617
 618	if (idle > 0) {
 619		wakeup = (needed > idle) ? idle : needed;
 620		needed -= wakeup;
 621
 622		dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
 623			"channel=%d\n", wakeup, ch->partid, ch->number);
 624
 625		/* only wakeup the requested number of kthreads */
 626		wake_up_nr(&ch->idle_wq, wakeup);
 627	}
 628
 629	if (needed <= 0)
 630		return;
 631
 632	if (needed + assigned > ch->kthreads_assigned_limit) {
 633		needed = ch->kthreads_assigned_limit - assigned;
 634		if (needed <= 0)
 635			return;
 636	}
 637
 638	dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
 639		needed, ch->partid, ch->number);
 640
 641	xpc_create_kthreads(ch, needed, 0);
 642}
 643
 644/*
 645 * This function is where XPC's kthreads wait for messages to deliver.
 646 */
 647static void
 648xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
 649{
 650	int (*n_of_deliverable_payloads) (struct xpc_channel *) =
 651		xpc_arch_ops.n_of_deliverable_payloads;
 652
 653	do {
 654		/* deliver messages to their intended recipients */
 655
 656		while (n_of_deliverable_payloads(ch) > 0 &&
 657		       !(ch->flags & XPC_C_DISCONNECTING)) {
 658			xpc_deliver_payload(ch);
 659		}
 660
 661		if (atomic_inc_return(&ch->kthreads_idle) >
 662		    ch->kthreads_idle_limit) {
 663			/* too many idle kthreads on this channel */
 664			atomic_dec(&ch->kthreads_idle);
 665			break;
 666		}
 667
 668		dev_dbg(xpc_chan, "idle kthread calling "
 669			"wait_event_interruptible_exclusive()\n");
 670
 671		(void)wait_event_interruptible_exclusive(ch->idle_wq,
 672				(n_of_deliverable_payloads(ch) > 0 ||
 673				 (ch->flags & XPC_C_DISCONNECTING)));
 674
 675		atomic_dec(&ch->kthreads_idle);
 676
 677	} while (!(ch->flags & XPC_C_DISCONNECTING));
 678}
 679
 680static int
 681xpc_kthread_start(void *args)
 682{
 683	short partid = XPC_UNPACK_ARG1(args);
 684	u16 ch_number = XPC_UNPACK_ARG2(args);
 685	struct xpc_partition *part = &xpc_partitions[partid];
 686	struct xpc_channel *ch;
 687	int n_needed;
 688	unsigned long irq_flags;
 689	int (*n_of_deliverable_payloads) (struct xpc_channel *) =
 690		xpc_arch_ops.n_of_deliverable_payloads;
 691
 692	dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
 693		partid, ch_number);
 694
 695	ch = &part->channels[ch_number];
 696
 697	if (!(ch->flags & XPC_C_DISCONNECTING)) {
 698
 699		/* let registerer know that connection has been established */
 700
 701		spin_lock_irqsave(&ch->lock, irq_flags);
 702		if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
 703			ch->flags |= XPC_C_CONNECTEDCALLOUT;
 704			spin_unlock_irqrestore(&ch->lock, irq_flags);
 705
 706			xpc_connected_callout(ch);
 707
 708			spin_lock_irqsave(&ch->lock, irq_flags);
 709			ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
 710			spin_unlock_irqrestore(&ch->lock, irq_flags);
 711
 712			/*
 713			 * It is possible that while the callout was being
 714			 * made that the remote partition sent some messages.
 715			 * If that is the case, we may need to activate
 716			 * additional kthreads to help deliver them. We only
 717			 * need one less than total #of messages to deliver.
 718			 */
 719			n_needed = n_of_deliverable_payloads(ch) - 1;
 720			if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
 721				xpc_activate_kthreads(ch, n_needed);
 722
 723		} else {
 724			spin_unlock_irqrestore(&ch->lock, irq_flags);
 725		}
 726
 727		xpc_kthread_waitmsgs(part, ch);
 728	}
 729
 730	/* let registerer know that connection is disconnecting */
 731
 732	spin_lock_irqsave(&ch->lock, irq_flags);
 733	if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
 734	    !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
 735		ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
 736		spin_unlock_irqrestore(&ch->lock, irq_flags);
 737
 738		xpc_disconnect_callout(ch, xpDisconnecting);
 739
 740		spin_lock_irqsave(&ch->lock, irq_flags);
 741		ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
 742	}
 743	spin_unlock_irqrestore(&ch->lock, irq_flags);
 744
 745	if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 746	    atomic_dec_return(&part->nchannels_engaged) == 0) {
 747		xpc_arch_ops.indicate_partition_disengaged(part);
 748	}
 749
 750	xpc_msgqueue_deref(ch);
 751
 752	dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 753		partid, ch_number);
 754
 755	xpc_part_deref(part);
 756	return 0;
 757}
 758
 759/*
 760 * For each partition that XPC has established communications with, there is
 761 * a minimum of one kernel thread assigned to perform any operation that
 762 * may potentially sleep or block (basically the callouts to the asynchronous
 763 * functions registered via xpc_connect()).
 764 *
 765 * Additional kthreads are created and destroyed by XPC as the workload
 766 * demands.
 767 *
 768 * A kthread is assigned to one of the active channels that exists for a given
 769 * partition.
 770 */
 771void
 772xpc_create_kthreads(struct xpc_channel *ch, int needed,
 773		    int ignore_disconnecting)
 774{
 775	unsigned long irq_flags;
 776	u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
 777	struct xpc_partition *part = &xpc_partitions[ch->partid];
 778	struct task_struct *kthread;
 779	void (*indicate_partition_disengaged) (struct xpc_partition *) =
 780		xpc_arch_ops.indicate_partition_disengaged;
 781
 782	while (needed-- > 0) {
 783
 784		/*
 785		 * The following is done on behalf of the newly created
 786		 * kthread. That kthread is responsible for doing the
 787		 * counterpart to the following before it exits.
 788		 */
 789		if (ignore_disconnecting) {
 790			if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
 791				/* kthreads assigned had gone to zero */
 792				BUG_ON(!(ch->flags &
 793					 XPC_C_DISCONNECTINGCALLOUT_MADE));
 794				break;
 795			}
 796
 797		} else if (ch->flags & XPC_C_DISCONNECTING) {
 798			break;
 799
 800		} else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
 801			   atomic_inc_return(&part->nchannels_engaged) == 1) {
 802			xpc_arch_ops.indicate_partition_engaged(part);
 803		}
 804		(void)xpc_part_ref(part);
 805		xpc_msgqueue_ref(ch);
 806
 807		kthread = kthread_run(xpc_kthread_start, (void *)args,
 808				      "xpc%02dc%d", ch->partid, ch->number);
 809		if (IS_ERR(kthread)) {
 810			/* the fork failed */
 811
 812			/*
 813			 * NOTE: if (ignore_disconnecting &&
 814			 * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
 815			 * then we'll deadlock if all other kthreads assigned
 816			 * to this channel are blocked in the channel's
 817			 * registerer, because the only thing that will unblock
 818			 * them is the xpDisconnecting callout that this
 819			 * failed kthread_run() would have made.
 820			 */
 821
 822			if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 823			    atomic_dec_return(&part->nchannels_engaged) == 0) {
 824				indicate_partition_disengaged(part);
 825			}
 826			xpc_msgqueue_deref(ch);
 827			xpc_part_deref(part);
 828
 829			if (atomic_read(&ch->kthreads_assigned) <
 830			    ch->kthreads_idle_limit) {
 831				/*
 832				 * Flag this as an error only if we have an
 833				 * insufficient #of kthreads for the channel
 834				 * to function.
 835				 */
 836				spin_lock_irqsave(&ch->lock, irq_flags);
 837				XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
 838						       &irq_flags);
 839				spin_unlock_irqrestore(&ch->lock, irq_flags);
 840			}
 841			break;
 842		}
 843	}
 844}
 845
 846void
 847xpc_disconnect_wait(int ch_number)
 848{
 849	unsigned long irq_flags;
 850	short partid;
 851	struct xpc_partition *part;
 852	struct xpc_channel *ch;
 853	int wakeup_channel_mgr;
 854
 855	/* now wait for all callouts to the caller's function to cease */
 856	for (partid = 0; partid < xp_max_npartitions; partid++) {
 857		part = &xpc_partitions[partid];
 858
 859		if (!xpc_part_ref(part))
 860			continue;
 861
 862		ch = &part->channels[ch_number];
 863
 864		if (!(ch->flags & XPC_C_WDISCONNECT)) {
 865			xpc_part_deref(part);
 866			continue;
 867		}
 868
 869		wait_for_completion(&ch->wdisconnect_wait);
 870
 871		spin_lock_irqsave(&ch->lock, irq_flags);
 872		DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 873		wakeup_channel_mgr = 0;
 874
 875		if (ch->delayed_chctl_flags) {
 876			if (part->act_state != XPC_P_AS_DEACTIVATING) {
 877				spin_lock(&part->chctl_lock);
 878				part->chctl.flags[ch->number] |=
 879				    ch->delayed_chctl_flags;
 880				spin_unlock(&part->chctl_lock);
 881				wakeup_channel_mgr = 1;
 882			}
 883			ch->delayed_chctl_flags = 0;
 884		}
 885
 886		ch->flags &= ~XPC_C_WDISCONNECT;
 887		spin_unlock_irqrestore(&ch->lock, irq_flags);
 888
 889		if (wakeup_channel_mgr)
 890			xpc_wakeup_channel_mgr(part);
 891
 892		xpc_part_deref(part);
 893	}
 894}
 895
 896static int
 897xpc_setup_partitions(void)
 898{
 899	short partid;
 900	struct xpc_partition *part;
 901
 902	xpc_partitions = kcalloc(xp_max_npartitions,
 903				 sizeof(struct xpc_partition),
 904				 GFP_KERNEL);
 905	if (xpc_partitions == NULL) {
 906		dev_err(xpc_part, "can't get memory for partition structure\n");
 907		return -ENOMEM;
 908	}
 909
 910	/*
 911	 * The first few fields of each entry of xpc_partitions[] need to
 912	 * be initialized now so that calls to xpc_connect() and
 913	 * xpc_disconnect() can be made prior to the activation of any remote
 914	 * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
 915	 * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
 916	 * PARTITION HAS BEEN ACTIVATED.
 917	 */
 918	for (partid = 0; partid < xp_max_npartitions; partid++) {
 919		part = &xpc_partitions[partid];
 920
 921		DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
 922
 923		part->activate_IRQ_rcvd = 0;
 924		spin_lock_init(&part->act_lock);
 925		part->act_state = XPC_P_AS_INACTIVE;
 926		XPC_SET_REASON(part, 0, 0);
 927
 928		timer_setup(&part->disengage_timer,
 929			    xpc_timeout_partition_disengage, 0);
 930
 931		part->setup_state = XPC_P_SS_UNSET;
 932		init_waitqueue_head(&part->teardown_wq);
 933		atomic_set(&part->references, 0);
 934	}
 935
 936	return xpc_arch_ops.setup_partitions();
 937}
 938
 939static void
 940xpc_teardown_partitions(void)
 941{
 942	xpc_arch_ops.teardown_partitions();
 943	kfree(xpc_partitions);
 944}
 945
 946static void
 947xpc_do_exit(enum xp_retval reason)
 948{
 949	short partid;
 950	int active_part_count, printed_waiting_msg = 0;
 951	struct xpc_partition *part;
 952	unsigned long printmsg_time, disengage_timeout = 0;
 953
 954	/* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 955	DBUG_ON(xpc_exiting == 1);
 956
 957	/*
 958	 * Let the heartbeat checker thread and the discovery thread
 959	 * (if one is running) know that they should exit. Also wake up
 960	 * the heartbeat checker thread in case it's sleeping.
 961	 */
 962	xpc_exiting = 1;
 963	wake_up_interruptible(&xpc_activate_IRQ_wq);
 964
 965	/* wait for the discovery thread to exit */
 966	wait_for_completion(&xpc_discovery_exited);
 967
 968	/* wait for the heartbeat checker thread to exit */
 969	wait_for_completion(&xpc_hb_checker_exited);
 970
 971	/* sleep for a 1/3 of a second or so */
 972	(void)msleep_interruptible(300);
 973
 974	/* wait for all partitions to become inactive */
 975
 976	printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
 977	xpc_disengage_timedout = 0;
 978
 979	do {
 980		active_part_count = 0;
 981
 982		for (partid = 0; partid < xp_max_npartitions; partid++) {
 983			part = &xpc_partitions[partid];
 984
 985			if (xpc_partition_disengaged(part) &&
 986			    part->act_state == XPC_P_AS_INACTIVE) {
 987				continue;
 988			}
 989
 990			active_part_count++;
 991
 992			XPC_DEACTIVATE_PARTITION(part, reason);
 993
 994			if (part->disengage_timeout > disengage_timeout)
 995				disengage_timeout = part->disengage_timeout;
 996		}
 997
 998		if (xpc_arch_ops.any_partition_engaged()) {
 999			if (time_is_before_jiffies(printmsg_time)) {
1000				dev_info(xpc_part, "waiting for remote "
1001					 "partitions to deactivate, timeout in "
1002					 "%ld seconds\n", (disengage_timeout -
1003					 jiffies) / HZ);
1004				printmsg_time = jiffies +
1005				    (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1006				printed_waiting_msg = 1;
1007			}
1008
1009		} else if (active_part_count > 0) {
1010			if (printed_waiting_msg) {
1011				dev_info(xpc_part, "waiting for local partition"
1012					 " to deactivate\n");
1013				printed_waiting_msg = 0;
1014			}
1015
1016		} else {
1017			if (!xpc_disengage_timedout) {
1018				dev_info(xpc_part, "all partitions have "
1019					 "deactivated\n");
1020			}
1021			break;
1022		}
1023
1024		/* sleep for a 1/3 of a second or so */
1025		(void)msleep_interruptible(300);
1026
1027	} while (1);
1028
1029	DBUG_ON(xpc_arch_ops.any_partition_engaged());
1030
1031	xpc_teardown_rsvd_page();
1032
1033	if (reason == xpUnloading) {
1034		(void)unregister_die_notifier(&xpc_die_notifier);
1035		(void)unregister_reboot_notifier(&xpc_reboot_notifier);
1036	}
1037
1038	/* clear the interface to XPC's functions */
1039	xpc_clear_interface();
1040
1041	if (xpc_sysctl)
1042		unregister_sysctl_table(xpc_sysctl);
1043
1044	xpc_teardown_partitions();
1045
1046	if (is_uv())
1047		xpc_exit_uv();
1048}
1049
1050/*
1051 * This function is called when the system is being rebooted.
1052 */
1053static int
1054xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1055{
1056	enum xp_retval reason;
1057
1058	switch (event) {
1059	case SYS_RESTART:
1060		reason = xpSystemReboot;
1061		break;
1062	case SYS_HALT:
1063		reason = xpSystemHalt;
1064		break;
1065	case SYS_POWER_OFF:
1066		reason = xpSystemPoweroff;
1067		break;
1068	default:
1069		reason = xpSystemGoingDown;
1070	}
1071
1072	xpc_do_exit(reason);
1073	return NOTIFY_DONE;
1074}
1075
1076/* Used to only allow one cpu to complete disconnect */
1077static unsigned int xpc_die_disconnecting;
1078
1079/*
1080 * Notify other partitions to deactivate from us by first disengaging from all
1081 * references to our memory.
1082 */
1083static void
1084xpc_die_deactivate(void)
1085{
1086	struct xpc_partition *part;
1087	short partid;
1088	int any_engaged;
1089	long keep_waiting;
1090	long wait_to_print;
1091
1092	if (cmpxchg(&xpc_die_disconnecting, 0, 1))
1093		return;
1094
1095	/* keep xpc_hb_checker thread from doing anything (just in case) */
1096	xpc_exiting = 1;
1097
1098	xpc_arch_ops.disallow_all_hbs();   /*indicate we're deactivated */
1099
1100	for (partid = 0; partid < xp_max_npartitions; partid++) {
1101		part = &xpc_partitions[partid];
1102
1103		if (xpc_arch_ops.partition_engaged(partid) ||
1104		    part->act_state != XPC_P_AS_INACTIVE) {
1105			xpc_arch_ops.request_partition_deactivation(part);
1106			xpc_arch_ops.indicate_partition_disengaged(part);
1107		}
1108	}
1109
1110	/*
1111	 * Though we requested that all other partitions deactivate from us,
1112	 * we only wait until they've all disengaged or we've reached the
1113	 * defined timelimit.
1114	 *
1115	 * Given that one iteration through the following while-loop takes
1116	 * approximately 200 microseconds, calculate the #of loops to take
1117	 * before bailing and the #of loops before printing a waiting message.
1118	 */
1119	keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1120	wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1121
1122	while (1) {
1123		any_engaged = xpc_arch_ops.any_partition_engaged();
1124		if (!any_engaged) {
1125			dev_info(xpc_part, "all partitions have deactivated\n");
1126			break;
1127		}
1128
1129		if (!keep_waiting--) {
1130			for (partid = 0; partid < xp_max_npartitions;
1131			     partid++) {
1132				if (xpc_arch_ops.partition_engaged(partid)) {
1133					dev_info(xpc_part, "deactivate from "
1134						 "remote partition %d timed "
1135						 "out\n", partid);
1136				}
1137			}
1138			break;
1139		}
1140
1141		if (!wait_to_print--) {
1142			dev_info(xpc_part, "waiting for remote partitions to "
1143				 "deactivate, timeout in %ld seconds\n",
1144				 keep_waiting / (1000 * 5));
1145			wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1146			    1000 * 5;
1147		}
1148
1149		udelay(200);
1150	}
1151}
1152
1153/*
1154 * This function is called when the system is being restarted or halted due
1155 * to some sort of system failure. If this is the case we need to notify the
1156 * other partitions to disengage from all references to our memory.
1157 * This function can also be called when our heartbeater could be offlined
1158 * for a time. In this case we need to notify other partitions to not worry
1159 * about the lack of a heartbeat.
1160 */
1161static int
1162xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args)
1163{
1164#ifdef CONFIG_IA64		/* !!! temporary kludge */
1165	switch (event) {
1166	case DIE_MACHINE_RESTART:
1167	case DIE_MACHINE_HALT:
1168		xpc_die_deactivate();
1169		break;
1170
1171	case DIE_KDEBUG_ENTER:
1172		/* Should lack of heartbeat be ignored by other partitions? */
1173		if (!xpc_kdebug_ignore)
1174			break;
1175
1176		/* fall through */
1177	case DIE_MCA_MONARCH_ENTER:
1178	case DIE_INIT_MONARCH_ENTER:
1179		xpc_arch_ops.offline_heartbeat();
1180		break;
1181
1182	case DIE_KDEBUG_LEAVE:
1183		/* Is lack of heartbeat being ignored by other partitions? */
1184		if (!xpc_kdebug_ignore)
1185			break;
1186
1187		/* fall through */
1188	case DIE_MCA_MONARCH_LEAVE:
1189	case DIE_INIT_MONARCH_LEAVE:
1190		xpc_arch_ops.online_heartbeat();
1191		break;
1192	}
1193#else
1194	struct die_args *die_args = _die_args;
1195
1196	switch (event) {
1197	case DIE_TRAP:
1198		if (die_args->trapnr == X86_TRAP_DF)
1199			xpc_die_deactivate();
1200
1201		if (((die_args->trapnr == X86_TRAP_MF) ||
1202		     (die_args->trapnr == X86_TRAP_XF)) &&
1203		    !user_mode(die_args->regs))
1204			xpc_die_deactivate();
1205
1206		break;
1207	case DIE_INT3:
1208	case DIE_DEBUG:
1209		break;
1210	case DIE_OOPS:
1211	case DIE_GPF:
1212	default:
1213		xpc_die_deactivate();
1214	}
1215#endif
1216
1217	return NOTIFY_DONE;
1218}
1219
1220int __init
1221xpc_init(void)
1222{
1223	int ret;
1224	struct task_struct *kthread;
1225
1226	dev_set_name(xpc_part, "part");
1227	dev_set_name(xpc_chan, "chan");
1228
1229	if (is_uv()) {
1230		ret = xpc_init_uv();
1231
1232	} else {
1233		ret = -ENODEV;
1234	}
1235
1236	if (ret != 0)
1237		return ret;
1238
1239	ret = xpc_setup_partitions();
1240	if (ret != 0) {
1241		dev_err(xpc_part, "can't get memory for partition structure\n");
1242		goto out_1;
1243	}
1244
1245	xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1246
1247	/*
1248	 * Fill the partition reserved page with the information needed by
1249	 * other partitions to discover we are alive and establish initial
1250	 * communications.
1251	 */
1252	ret = xpc_setup_rsvd_page();
1253	if (ret != 0) {
1254		dev_err(xpc_part, "can't setup our reserved page\n");
1255		goto out_2;
1256	}
1257
1258	/* add ourselves to the reboot_notifier_list */
1259	ret = register_reboot_notifier(&xpc_reboot_notifier);
1260	if (ret != 0)
1261		dev_warn(xpc_part, "can't register reboot notifier\n");
1262
1263	/* add ourselves to the die_notifier list */
1264	ret = register_die_notifier(&xpc_die_notifier);
1265	if (ret != 0)
1266		dev_warn(xpc_part, "can't register die notifier\n");
1267
1268	/*
1269	 * The real work-horse behind xpc.  This processes incoming
1270	 * interrupts and monitors remote heartbeats.
1271	 */
1272	kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1273	if (IS_ERR(kthread)) {
1274		dev_err(xpc_part, "failed while forking hb check thread\n");
1275		ret = -EBUSY;
1276		goto out_3;
1277	}
1278
1279	/*
1280	 * Startup a thread that will attempt to discover other partitions to
1281	 * activate based on info provided by SAL. This new thread is short
1282	 * lived and will exit once discovery is complete.
1283	 */
1284	kthread = kthread_run(xpc_initiate_discovery, NULL,
1285			      XPC_DISCOVERY_THREAD_NAME);
1286	if (IS_ERR(kthread)) {
1287		dev_err(xpc_part, "failed while forking discovery thread\n");
1288
1289		/* mark this new thread as a non-starter */
1290		complete(&xpc_discovery_exited);
1291
1292		xpc_do_exit(xpUnloading);
1293		return -EBUSY;
1294	}
1295
1296	/* set the interface to point at XPC's functions */
1297	xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1298			  xpc_initiate_send, xpc_initiate_send_notify,
1299			  xpc_initiate_received, xpc_initiate_partid_to_nasids);
1300
1301	return 0;
1302
1303	/* initialization was not successful */
1304out_3:
1305	xpc_teardown_rsvd_page();
1306
1307	(void)unregister_die_notifier(&xpc_die_notifier);
1308	(void)unregister_reboot_notifier(&xpc_reboot_notifier);
1309out_2:
1310	if (xpc_sysctl)
1311		unregister_sysctl_table(xpc_sysctl);
1312
1313	xpc_teardown_partitions();
1314out_1:
1315	if (is_uv())
1316		xpc_exit_uv();
1317	return ret;
1318}
1319
1320module_init(xpc_init);
1321
1322void __exit
1323xpc_exit(void)
1324{
1325	xpc_do_exit(xpUnloading);
1326}
1327
1328module_exit(xpc_exit);
1329
1330MODULE_AUTHOR("Silicon Graphics, Inc.");
1331MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1332MODULE_LICENSE("GPL");
1333
1334module_param(xpc_hb_interval, int, 0);
1335MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1336		 "heartbeat increments.");
1337
1338module_param(xpc_hb_check_interval, int, 0);
1339MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1340		 "heartbeat checks.");
1341
1342module_param(xpc_disengage_timelimit, int, 0);
1343MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1344		 "for disengage to complete.");
1345
1346module_param(xpc_kdebug_ignore, int, 0);
1347MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1348		 "other partitions when dropping into kdebug.");