arch/ia64/sn/kernel/xpc_main.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (c) 2004-2005 Silicon Graphics, Inc.  All Rights Reserved.
   7  */
   8
   9
  10 /*
  11  * Cross Partition Communication (XPC) support - standard version.
  12  *
  13  *      XPC provides a message passing capability that crosses partition
  14  *      boundaries. This module is made up of two parts:
  15  *
  16  *          partition   This part detects the presence/absence of other
  17  *                      partitions. It provides a heartbeat and monitors
  18  *                      the heartbeats of other partitions.
  19  *
  20  *          channel     This part manages the channels and sends/receives
  21  *                      messages across them to/from other partitions.
  22  *
  23  *      There are a couple of additional functions residing in XP, which
  24  *      provide an interface to XPC for its users.
  25  *
  26  *
  27  *      Caveats:
  28  *
  29  *        . We currently have no way to determine which nasid an IPI came
  30  *          from. Thus, xpc_IPI_send() does a remote AMO write followed by
  31  *          an IPI. The AMO indicates where data is to be pulled from, so
  32  *          after the IPI arrives, the remote partition checks the AMO word.
  33  *          The IPI can actually arrive before the AMO however, so other code
  34  *          must periodically check for this case. Also, remote AMO operations
  35  *          do not reliably time out. Thus we do a remote PIO read solely to
  36  *          know whether the remote partition is down and whether we should
  37  *          stop sending IPIs to it. This remote PIO read operation is set up
  38  *          in a special nofault region so SAL knows to ignore (and cleanup)
  39  *          any errors due to the remote AMO write, PIO read, and/or PIO
  40  *          write operations.
  41  *
  42  *          If/when new hardware solves this IPI problem, we should abandon
  43  *          the current approach.
  44  *
  45  */
  46
  47
  48 #include <linux/kernel.h>
  49 #include <linux/module.h>
  50 #include <linux/init.h>
  51 #include <linux/sched.h>
  52 #include <linux/syscalls.h>
  53 #include <linux/cache.h>
  54 #include <linux/interrupt.h>
  55 #include <linux/slab.h>
  56 #include <linux/delay.h>
  57 #include <linux/reboot.h>
  58 #include <asm/sn/intr.h>
  59 #include <asm/sn/sn_sal.h>
  60 #include <asm/kdebug.h>
  61 #include <asm/uaccess.h>
  62 #include "xpc.h"
  63
  64
  65 /* define two XPC debug device structures to be used with dev_dbg() et al */
  66
  67 struct device_driver xpc_dbg_name = {
  68         .name = "xpc"
  69 };
  70
  71 struct device xpc_part_dbg_subname = {
  72         .bus_id = {0},          /* set to "part" at xpc_init() time */
  73         .driver = &xpc_dbg_name
  74 };
  75
  76 struct device xpc_chan_dbg_subname = {
  77         .bus_id = {0},          /* set to "chan" at xpc_init() time */
  78         .driver = &xpc_dbg_name
  79 };
  80
  81 struct device *xpc_part = &xpc_part_dbg_subname;
  82 struct device *xpc_chan = &xpc_chan_dbg_subname;
  83
  84
  85 /* systune related variables for /proc/sys directories */
  86
  87 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
  88 static int xpc_hb_min_interval = 1;
  89 static int xpc_hb_max_interval = 10;
  90
  91 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
  92 static int xpc_hb_check_min_interval = 10;
  93 static int xpc_hb_check_max_interval = 120;
  94
  95 int xpc_disengage_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
  96 static int xpc_disengage_request_min_timelimit = 0;
  97 static int xpc_disengage_request_max_timelimit = 120;
  98
  99 static ctl_table xpc_sys_xpc_hb_dir[] = {
 100         {
 101                 1,
 102                 "hb_interval",
 103                 &xpc_hb_interval,
 104                 sizeof(int),
 105                 0644,
 106                 NULL,
 107                 &proc_dointvec_minmax,
 108                 &sysctl_intvec,
 109                 NULL,
 110                 &xpc_hb_min_interval,
 111                 &xpc_hb_max_interval
 112         },
 113         {
 114                 2,
 115                 "hb_check_interval",
 116                 &xpc_hb_check_interval,
 117                 sizeof(int),
 118                 0644,
 119                 NULL,
 120                 &proc_dointvec_minmax,
 121                 &sysctl_intvec,
 122                 NULL,
 123                 &xpc_hb_check_min_interval,
 124                 &xpc_hb_check_max_interval
 125         },
 126         {0}
 127 };
 128 static ctl_table xpc_sys_xpc_dir[] = {
 129         {
 130                 1,
 131                 "hb",
 132                 NULL,
 133                 0,
 134                 0555,
 135                 xpc_sys_xpc_hb_dir
 136         },
 137         {
 138                 2,
 139                 "disengage_request_timelimit",
 140                 &xpc_disengage_request_timelimit,
 141                 sizeof(int),
 142                 0644,
 143                 NULL,
 144                 &proc_dointvec_minmax,
 145                 &sysctl_intvec,
 146                 NULL,
 147                 &xpc_disengage_request_min_timelimit,
 148                 &xpc_disengage_request_max_timelimit
 149         },
 150         {0}
 151 };
 152 static ctl_table xpc_sys_dir[] = {
 153         {
 154                 1,
 155                 "xpc",
 156                 NULL,
 157                 0,
 158                 0555,
 159                 xpc_sys_xpc_dir
 160         },
 161         {0}
 162 };
 163 static struct ctl_table_header *xpc_sysctl;
 164
 165
 166 /* #of IRQs received */
 167 static atomic_t xpc_act_IRQ_rcvd;
 168
 169 /* IRQ handler notifies this wait queue on receipt of an IRQ */
 170 static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
 171
 172 static unsigned long xpc_hb_check_timeout;
 173
 174 /* notification that the xpc_hb_checker thread has exited */
 175 static DECLARE_MUTEX_LOCKED(xpc_hb_checker_exited);
 176
 177 /* notification that the xpc_discovery thread has exited */
 178 static DECLARE_MUTEX_LOCKED(xpc_discovery_exited);
 179
 180
 181 static struct timer_list xpc_hb_timer;
 182
 183
 184 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
 185
 186
 187 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
 188 static struct notifier_block xpc_reboot_notifier = {
 189         .notifier_call = xpc_system_reboot,
 190 };
 191
 192 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
 193 static struct notifier_block xpc_die_notifier = {
 194         .notifier_call = xpc_system_die,
 195 };
 196
 197
 198 /*
 199  * Timer function to enforce the timelimit on the partition disengage request.
 200  */
 201 static void
 202 xpc_timeout_partition_disengage_request(unsigned long data)
 203 {
 204         struct xpc_partition *part = (struct xpc_partition *) data;
 205
 206
 207         DBUG_ON(jiffies < part->disengage_request_timeout);
 208
 209         (void) xpc_partition_disengaged(part);
 210
 211         DBUG_ON(part->disengage_request_timeout != 0);
 212         DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
 213 }
 214
 215
 216 /*
 217  * Notify the heartbeat check thread that an IRQ has been received.
 218  */
 219 static irqreturn_t
 220 xpc_act_IRQ_handler(int irq, void *dev_id, struct pt_regs *regs)
 221 {
 222         atomic_inc(&xpc_act_IRQ_rcvd);
 223         wake_up_interruptible(&xpc_act_IRQ_wq);
 224         return IRQ_HANDLED;
 225 }
 226
 227
 228 /*
 229  * Timer to produce the heartbeat.  The timer structures function is
 230  * already set when this is initially called.  A tunable is used to
 231  * specify when the next timeout should occur.
 232  */
 233 static void
 234 xpc_hb_beater(unsigned long dummy)
 235 {
 236         xpc_vars->heartbeat++;
 237
 238         if (jiffies >= xpc_hb_check_timeout) {
 239                 wake_up_interruptible(&xpc_act_IRQ_wq);
 240         }
 241
 242         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
 243         add_timer(&xpc_hb_timer);
 244 }
 245
 246
 247 /*
 248  * This thread is responsible for nearly all of the partition
 249  * activation/deactivation.
 250  */
 251 static int
 252 xpc_hb_checker(void *ignore)
 253 {
 254         int last_IRQ_count = 0;
 255         int new_IRQ_count;
 256         int force_IRQ=0;
 257
 258
 259         /* this thread was marked active by xpc_hb_init() */
 260
 261         daemonize(XPC_HB_CHECK_THREAD_NAME);
 262
 263         set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
 264
 265         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
 266
 267         while (!(volatile int) xpc_exiting) {
 268
 269                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
 270                         "been received\n",
 271                         (int) (xpc_hb_check_timeout - jiffies),
 272                         atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
 273
 274
 275                 /* checking of remote heartbeats is skewed by IRQ handling */
 276                 if (jiffies >= xpc_hb_check_timeout) {
 277                         dev_dbg(xpc_part, "checking remote heartbeats\n");
 278                         xpc_check_remote_hb();
 279
 280                         /*
 281                          * We need to periodically recheck to ensure no
 282                          * IPI/AMO pairs have been missed.  That check
 283                          * must always reset xpc_hb_check_timeout.
 284                          */
 285                         force_IRQ = 1;
 286                 }
 287
 288
 289                 /* check for outstanding IRQs */
 290                 new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
 291                 if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
 292                         force_IRQ = 0;
 293
 294                         dev_dbg(xpc_part, "found an IRQ to process; will be "
 295                                 "resetting xpc_hb_check_timeout\n");
 296
 297                         last_IRQ_count += xpc_identify_act_IRQ_sender();
 298                         if (last_IRQ_count < new_IRQ_count) {
 299                                 /* retry once to help avoid missing AMO */
 300                                 (void) xpc_identify_act_IRQ_sender();
 301                         }
 302                         last_IRQ_count = new_IRQ_count;
 303
 304                         xpc_hb_check_timeout = jiffies +
 305                                            (xpc_hb_check_interval * HZ);
 306                 }
 307
 308                 /* wait for IRQ or timeout */
 309                 (void) wait_event_interruptible(xpc_act_IRQ_wq,
 310                             (last_IRQ_count < atomic_read(&xpc_act_IRQ_rcvd) ||
 311                                         jiffies >= xpc_hb_check_timeout ||
 312                                                 (volatile int) xpc_exiting));
 313         }
 314
 315         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 316
 317
 318         /* mark this thread as having exited */
 319         up(&xpc_hb_checker_exited);
 320         return 0;
 321 }
 322
 323
 324 /*
 325  * This thread will attempt to discover other partitions to activate
 326  * based on info provided by SAL. This new thread is short lived and
 327  * will exit once discovery is complete.
 328  */
 329 static int
 330 xpc_initiate_discovery(void *ignore)
 331 {
 332         daemonize(XPC_DISCOVERY_THREAD_NAME);
 333
 334         xpc_discovery();
 335
 336         dev_dbg(xpc_part, "discovery thread is exiting\n");
 337
 338         /* mark this thread as having exited */
 339         up(&xpc_discovery_exited);
 340         return 0;
 341 }
 342
 343
 344 /*
 345  * Establish first contact with the remote partititon. This involves pulling
 346  * the XPC per partition variables from the remote partition and waiting for
 347  * the remote partition to pull ours.
 348  */
 349 static enum xpc_retval
 350 xpc_make_first_contact(struct xpc_partition *part)
 351 {
 352         enum xpc_retval ret;
 353
 354
 355         while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
 356                 if (ret != xpcRetry) {
 357                         XPC_DEACTIVATE_PARTITION(part, ret);
 358                         return ret;
 359                 }
 360
 361                 dev_dbg(xpc_chan, "waiting to make first contact with "
 362                         "partition %d\n", XPC_PARTID(part));
 363
 364                 /* wait a 1/4 of a second or so */
 365                 (void) msleep_interruptible(250);
 366
 367                 if (part->act_state == XPC_P_DEACTIVATING) {
 368                         return part->reason;
 369                 }
 370         }
 371
 372         return xpc_mark_partition_active(part);
 373 }
 374
 375
 376 /*
 377  * The first kthread assigned to a newly activated partition is the one
 378  * created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
 379  * that kthread until the partition is brought down, at which time that kthread
 380  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
 381  * that XPC has dismantled all communication infrastructure for the associated
 382  * partition.) This kthread becomes the channel manager for that partition.
 383  *
 384  * Each active partition has a channel manager, who, besides connecting and
 385  * disconnecting channels, will ensure that each of the partition's connected
 386  * channels has the required number of assigned kthreads to get the work done.
 387  */
 388 static void
 389 xpc_channel_mgr(struct xpc_partition *part)
 390 {
 391         while (part->act_state != XPC_P_DEACTIVATING ||
 392                         atomic_read(&part->nchannels_active) > 0 ||
 393                                         !xpc_partition_disengaged(part)) {
 394
 395                 xpc_process_channel_activity(part);
 396
 397
 398                 /*
 399                  * Wait until we've been requested to activate kthreads or
 400                  * all of the channel's message queues have been torn down or
 401                  * a signal is pending.
 402                  *
 403                  * The channel_mgr_requests is set to 1 after being awakened,
 404                  * This is done to prevent the channel mgr from making one pass
 405                  * through the loop for each request, since he will
 406                  * be servicing all the requests in one pass. The reason it's
 407                  * set to 1 instead of 0 is so that other kthreads will know
 408                  * that the channel mgr is running and won't bother trying to
 409                  * wake him up.
 410                  */
 411                 atomic_dec(&part->channel_mgr_requests);
 412                 (void) wait_event_interruptible(part->channel_mgr_wq,
 413                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
 414                                 (volatile u64) part->local_IPI_amo != 0 ||
 415                                 ((volatile u8) part->act_state ==
 416                                                         XPC_P_DEACTIVATING &&
 417                                 atomic_read(&part->nchannels_active) == 0 &&
 418                                 xpc_partition_disengaged(part))));
 419                 atomic_set(&part->channel_mgr_requests, 1);
 420
 421                 // >>> Does it need to wakeup periodically as well? In case we
 422                 // >>> miscalculated the #of kthreads to wakeup or create?
 423         }
 424 }
 425
 426
 427 /*
 428  * When XPC HB determines that a partition has come up, it will create a new
 429  * kthread and that kthread will call this function to attempt to set up the
 430  * basic infrastructure used for Cross Partition Communication with the newly
 431  * upped partition.
 432  *
 433  * The kthread that was created by XPC HB and which setup the XPC
 434  * infrastructure will remain assigned to the partition until the partition
 435  * goes down. At which time the kthread will teardown the XPC infrastructure
 436  * and then exit.
 437  *
 438  * XPC HB will put the remote partition's XPC per partition specific variables
 439  * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
 440  * calling xpc_partition_up().
 441  */
 442 static void
 443 xpc_partition_up(struct xpc_partition *part)
 444 {
 445         DBUG_ON(part->channels != NULL);
 446
 447         dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
 448
 449         if (xpc_setup_infrastructure(part) != xpcSuccess) {
 450                 return;
 451         }
 452
 453         /*
 454          * The kthread that XPC HB called us with will become the
 455          * channel manager for this partition. It will not return
 456          * back to XPC HB until the partition's XPC infrastructure
 457          * has been dismantled.
 458          */
 459
 460         (void) xpc_part_ref(part);      /* this will always succeed */
 461
 462         if (xpc_make_first_contact(part) == xpcSuccess) {
 463                 xpc_channel_mgr(part);
 464         }
 465
 466         xpc_part_deref(part);
 467
 468         xpc_teardown_infrastructure(part);
 469 }
 470
 471
 472 static int
 473 xpc_activating(void *__partid)
 474 {
 475         partid_t partid = (u64) __partid;
 476         struct xpc_partition *part = &xpc_partitions[partid];
 477         unsigned long irq_flags;
 478         struct sched_param param = { sched_priority: MAX_RT_PRIO - 1 };
 479         int ret;
 480
 481
 482         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 483
 484         spin_lock_irqsave(&part->act_lock, irq_flags);
 485
 486         if (part->act_state == XPC_P_DEACTIVATING) {
 487                 part->act_state = XPC_P_INACTIVE;
 488                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 489                 part->remote_rp_pa = 0;
 490                 return 0;
 491         }
 492
 493         /* indicate the thread is activating */
 494         DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
 495         part->act_state = XPC_P_ACTIVATING;
 496
 497         XPC_SET_REASON(part, 0, 0);
 498         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 499
 500         dev_dbg(xpc_part, "bringing partition %d up\n", partid);
 501
 502         daemonize("xpc%02d", partid);
 503
 504         /*
 505          * This thread needs to run at a realtime priority to prevent a
 506          * significant performance degradation.
 507          */
 508         ret = sched_setscheduler(current, SCHED_FIFO, &param);
 509         if (ret != 0) {
 510                 dev_warn(xpc_part, "unable to set pid %d to a realtime "
 511                         "priority, ret=%d\n", current->pid, ret);
 512         }
 513
 514         /* allow this thread and its children to run on any CPU */
 515         set_cpus_allowed(current, CPU_MASK_ALL);
 516
 517         /*
 518          * Register the remote partition's AMOs with SAL so it can handle
 519          * and cleanup errors within that address range should the remote
 520          * partition go down. We don't unregister this range because it is
 521          * difficult to tell when outstanding writes to the remote partition
 522          * are finished and thus when it is safe to unregister. This should
 523          * not result in wasted space in the SAL xp_addr_region table because
 524          * we should get the same page for remote_amos_page_pa after module
 525          * reloads and system reboots.
 526          */
 527         if (sn_register_xp_addr_region(part->remote_amos_page_pa,
 528                                                         PAGE_SIZE, 1) < 0) {
 529                 dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
 530                         "xp_addr region\n", partid);
 531
 532                 spin_lock_irqsave(&part->act_lock, irq_flags);
 533                 part->act_state = XPC_P_INACTIVE;
 534                 XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
 535                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
 536                 part->remote_rp_pa = 0;
 537                 return 0;
 538         }
 539
 540         xpc_allow_hb(partid, xpc_vars);
 541         xpc_IPI_send_activated(part);
 542
 543
 544         /*
 545          * xpc_partition_up() holds this thread and marks this partition as
 546          * XPC_P_ACTIVE by calling xpc_hb_mark_active().
 547          */
 548         (void) xpc_partition_up(part);
 549
 550         xpc_disallow_hb(partid, xpc_vars);
 551         xpc_mark_partition_inactive(part);
 552
 553         if (part->reason == xpcReactivating) {
 554                 /* interrupting ourselves results in activating partition */
 555                 xpc_IPI_send_reactivate(part);
 556         }
 557
 558         return 0;
 559 }
 560
 561
 562 void
 563 xpc_activate_partition(struct xpc_partition *part)
 564 {
 565         partid_t partid = XPC_PARTID(part);
 566         unsigned long irq_flags;
 567         pid_t pid;
 568
 569
 570         spin_lock_irqsave(&part->act_lock, irq_flags);
 571
 572         pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
 573
 574         DBUG_ON(part->act_state != XPC_P_INACTIVE);
 575
 576         if (pid > 0) {
 577                 part->act_state = XPC_P_ACTIVATION_REQ;
 578                 XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
 579         } else {
 580                 XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
 581         }
 582
 583         spin_unlock_irqrestore(&part->act_lock, irq_flags);
 584 }
 585
 586
 587 /*
 588  * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
 589  * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
 590  * than one partition, we use an AMO_t structure per partition to indicate
 591  * whether a partition has sent an IPI or not.  >>> If it has, then wake up the
 592  * associated kthread to handle it.
 593  *
 594  * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
 595  * running on other partitions.
 596  *
 597  * Noteworthy Arguments:
 598  *
 599  *      irq - Interrupt ReQuest number. NOT USED.
 600  *
 601  *      dev_id - partid of IPI's potential sender.
 602  *
 603  *      regs - processor's context before the processor entered
 604  *             interrupt code. NOT USED.
 605  */
 606 irqreturn_t
 607 xpc_notify_IRQ_handler(int irq, void *dev_id, struct pt_regs *regs)
 608 {
 609         partid_t partid = (partid_t) (u64) dev_id;
 610         struct xpc_partition *part = &xpc_partitions[partid];
 611
 612
 613         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
 614
 615         if (xpc_part_ref(part)) {
 616                 xpc_check_for_channel_activity(part);
 617
 618                 xpc_part_deref(part);
 619         }
 620         return IRQ_HANDLED;
 621 }
 622
 623
 624 /*
 625  * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
 626  * because the write to their associated IPI amo completed after the IRQ/IPI
 627  * was received.
 628  */
 629 void
 630 xpc_dropped_IPI_check(struct xpc_partition *part)
 631 {
 632         if (xpc_part_ref(part)) {
 633                 xpc_check_for_channel_activity(part);
 634
 635                 part->dropped_IPI_timer.expires = jiffies +
 636                                                         XPC_P_DROPPED_IPI_WAIT;
 637                 add_timer(&part->dropped_IPI_timer);
 638                 xpc_part_deref(part);
 639         }
 640 }
 641
 642
 643 void
 644 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
 645 {
 646         int idle = atomic_read(&ch->kthreads_idle);
 647         int assigned = atomic_read(&ch->kthreads_assigned);
 648         int wakeup;
 649
 650
 651         DBUG_ON(needed <= 0);
 652
 653         if (idle > 0) {
 654                 wakeup = (needed > idle) ? idle : needed;
 655                 needed -= wakeup;
 656
 657                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
 658                         "channel=%d\n", wakeup, ch->partid, ch->number);
 659
 660                 /* only wakeup the requested number of kthreads */
 661                 wake_up_nr(&ch->idle_wq, wakeup);
 662         }
 663
 664         if (needed <= 0) {
 665                 return;
 666         }
 667
 668         if (needed + assigned > ch->kthreads_assigned_limit) {
 669                 needed = ch->kthreads_assigned_limit - assigned;
 670                 // >>>should never be less than 0
 671                 if (needed <= 0) {
 672                         return;
 673                 }
 674         }
 675
 676         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
 677                 needed, ch->partid, ch->number);
 678
 679         xpc_create_kthreads(ch, needed);
 680 }
 681
 682
 683 /*
 684  * This function is where XPC's kthreads wait for messages to deliver.
 685  */
 686 static void
 687 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
 688 {
 689         do {
 690                 /* deliver messages to their intended recipients */
 691
 692                 while ((volatile s64) ch->w_local_GP.get <
 693                                 (volatile s64) ch->w_remote_GP.put &&
 694                                         !((volatile u32) ch->flags &
 695                                                 XPC_C_DISCONNECTING)) {
 696                         xpc_deliver_msg(ch);
 697                 }
 698
 699                 if (atomic_inc_return(&ch->kthreads_idle) >
 700                                                 ch->kthreads_idle_limit) {
 701                         /* too many idle kthreads on this channel */
 702                         atomic_dec(&ch->kthreads_idle);
 703                         break;
 704                 }
 705
 706                 dev_dbg(xpc_chan, "idle kthread calling "
 707                         "wait_event_interruptible_exclusive()\n");
 708
 709                 (void) wait_event_interruptible_exclusive(ch->idle_wq,
 710                                 ((volatile s64) ch->w_local_GP.get <
 711                                         (volatile s64) ch->w_remote_GP.put ||
 712                                 ((volatile u32) ch->flags &
 713                                                 XPC_C_DISCONNECTING)));
 714
 715                 atomic_dec(&ch->kthreads_idle);
 716
 717         } while (!((volatile u32) ch->flags & XPC_C_DISCONNECTING));
 718 }
 719
 720
 721 static int
 722 xpc_daemonize_kthread(void *args)
 723 {
 724         partid_t partid = XPC_UNPACK_ARG1(args);
 725         u16 ch_number = XPC_UNPACK_ARG2(args);
 726         struct xpc_partition *part = &xpc_partitions[partid];
 727         struct xpc_channel *ch;
 728         int n_needed;
 729         unsigned long irq_flags;
 730
 731
 732         daemonize("xpc%02dc%d", partid, ch_number);
 733
 734         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
 735                 partid, ch_number);
 736
 737         ch = &part->channels[ch_number];
 738
 739         if (!(ch->flags & XPC_C_DISCONNECTING)) {
 740
 741                 /* let registerer know that connection has been established */
 742
 743                 spin_lock_irqsave(&ch->lock, irq_flags);
 744                 if (!(ch->flags & XPC_C_CONNECTCALLOUT)) {
 745                         ch->flags |= XPC_C_CONNECTCALLOUT;
 746                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 747
 748                         xpc_connected_callout(ch);
 749
 750                         /*
 751                          * It is possible that while the callout was being
 752                          * made that the remote partition sent some messages.
 753                          * If that is the case, we may need to activate
 754                          * additional kthreads to help deliver them. We only
 755                          * need one less than total #of messages to deliver.
 756                          */
 757                         n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
 758                         if (n_needed > 0 &&
 759                                         !(ch->flags & XPC_C_DISCONNECTING)) {
 760                                 xpc_activate_kthreads(ch, n_needed);
 761                         }
 762                 } else {
 763                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 764                 }
 765
 766                 xpc_kthread_waitmsgs(part, ch);
 767         }
 768
 769         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
 770                 spin_lock_irqsave(&ch->lock, irq_flags);
 771                 if ((ch->flags & XPC_C_CONNECTCALLOUT) &&
 772                                 !(ch->flags & XPC_C_DISCONNECTCALLOUT)) {
 773                         ch->flags |= XPC_C_DISCONNECTCALLOUT;
 774                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 775
 776                         xpc_disconnecting_callout(ch);
 777                 } else {
 778                         spin_unlock_irqrestore(&ch->lock, irq_flags);
 779                 }
 780                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
 781                         xpc_mark_partition_disengaged(part);
 782                         xpc_IPI_send_disengage(part);
 783                 }
 784         }
 785
 786
 787         xpc_msgqueue_deref(ch);
 788
 789         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
 790                 partid, ch_number);
 791
 792         xpc_part_deref(part);
 793         return 0;
 794 }
 795
 796
 797 /*
 798  * For each partition that XPC has established communications with, there is
 799  * a minimum of one kernel thread assigned to perform any operation that
 800  * may potentially sleep or block (basically the callouts to the asynchronous
 801  * functions registered via xpc_connect()).
 802  *
 803  * Additional kthreads are created and destroyed by XPC as the workload
 804  * demands.
 805  *
 806  * A kthread is assigned to one of the active channels that exists for a given
 807  * partition.
 808  */
 809 void
 810 xpc_create_kthreads(struct xpc_channel *ch, int needed)
 811 {
 812         unsigned long irq_flags;
 813         pid_t pid;
 814         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
 815         struct xpc_partition *part = &xpc_partitions[ch->partid];
 816
 817
 818         while (needed-- > 0) {
 819
 820                 /*
 821                  * The following is done on behalf of the newly created
 822                  * kthread. That kthread is responsible for doing the
 823                  * counterpart to the following before it exits.
 824                  */
 825                 (void) xpc_part_ref(part);
 826                 xpc_msgqueue_ref(ch);
 827                 if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
 828                     atomic_inc_return(&part->nchannels_engaged) == 1) {
 829                         xpc_mark_partition_engaged(part);
 830                 }
 831
 832                 pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
 833                 if (pid < 0) {
 834                         /* the fork failed */
 835                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
 836                             atomic_dec_return(&part->nchannels_engaged) == 0) {
 837                                 xpc_mark_partition_disengaged(part);
 838                                 xpc_IPI_send_disengage(part);
 839                         }
 840                         xpc_msgqueue_deref(ch);
 841                         xpc_part_deref(part);
 842
 843                         if (atomic_read(&ch->kthreads_assigned) <
 844                                                 ch->kthreads_idle_limit) {
 845                                 /*
 846                                  * Flag this as an error only if we have an
 847                                  * insufficient #of kthreads for the channel
 848                                  * to function.
 849                                  *
 850                                  * No xpc_msgqueue_ref() is needed here since
 851                                  * the channel mgr is doing this.
 852                                  */
 853                                 spin_lock_irqsave(&ch->lock, irq_flags);
 854                                 XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
 855                                                                 &irq_flags);
 856                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 857                         }
 858                         break;
 859                 }
 860
 861                 ch->kthreads_created++; // >>> temporary debug only!!!
 862         }
 863 }
 864
 865
 866 void
 867 xpc_disconnect_wait(int ch_number)
 868 {
 869         unsigned long irq_flags;
 870         partid_t partid;
 871         struct xpc_partition *part;
 872         struct xpc_channel *ch;
 873         int wakeup_channel_mgr;
 874
 875
 876         /* now wait for all callouts to the caller's function to cease */
 877         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 878                 part = &xpc_partitions[partid];
 879
 880                 if (!xpc_part_ref(part)) {
 881                         continue;
 882                 }
 883
 884                 ch = &part->channels[ch_number];
 885
 886                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
 887                         xpc_part_deref(part);
 888                         continue;
 889                 }
 890
 891                 (void) down(&ch->wdisconnect_sema);
 892
 893                 spin_lock_irqsave(&ch->lock, irq_flags);
 894                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
 895                 wakeup_channel_mgr = 0;
 896
 897                 if (ch->delayed_IPI_flags) {
 898                         if (part->act_state != XPC_P_DEACTIVATING) {
 899                                 spin_lock(&part->IPI_lock);
 900                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
 901                                         ch->number, ch->delayed_IPI_flags);
 902                                 spin_unlock(&part->IPI_lock);
 903                                 wakeup_channel_mgr = 1;
 904                         }
 905                         ch->delayed_IPI_flags = 0;
 906                 }
 907
 908                 ch->flags &= ~XPC_C_WDISCONNECT;
 909                 spin_unlock_irqrestore(&ch->lock, irq_flags);
 910
 911                 if (wakeup_channel_mgr) {
 912                         xpc_wakeup_channel_mgr(part);
 913                 }
 914
 915                 xpc_part_deref(part);
 916         }
 917 }
 918
 919
 920 static void
 921 xpc_do_exit(enum xpc_retval reason)
 922 {
 923         partid_t partid;
 924         int active_part_count;
 925         struct xpc_partition *part;
 926         unsigned long printmsg_time;
 927
 928
 929         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
 930         DBUG_ON(xpc_exiting == 1);
 931
 932         /*
 933          * Let the heartbeat checker thread and the discovery thread
 934          * (if one is running) know that they should exit. Also wake up
 935          * the heartbeat checker thread in case it's sleeping.
 936          */
 937         xpc_exiting = 1;
 938         wake_up_interruptible(&xpc_act_IRQ_wq);
 939
 940         /* ignore all incoming interrupts */
 941         free_irq(SGI_XPC_ACTIVATE, NULL);
 942
 943         /* wait for the discovery thread to exit */
 944         down(&xpc_discovery_exited);
 945
 946         /* wait for the heartbeat checker thread to exit */
 947         down(&xpc_hb_checker_exited);
 948
 949
 950         /* sleep for a 1/3 of a second or so */
 951         (void) msleep_interruptible(300);
 952
 953
 954         /* wait for all partitions to become inactive */
 955
 956         printmsg_time = jiffies;
 957
 958         do {
 959                 active_part_count = 0;
 960
 961                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
 962                         part = &xpc_partitions[partid];
 963
 964                         if (xpc_partition_disengaged(part) &&
 965                                         part->act_state == XPC_P_INACTIVE) {
 966                                 continue;
 967                         }
 968
 969                         active_part_count++;
 970
 971                         XPC_DEACTIVATE_PARTITION(part, reason);
 972                 }
 973
 974                 if (active_part_count == 0) {
 975                         break;
 976                 }
 977
 978                 if (jiffies >= printmsg_time) {
 979                         dev_info(xpc_part, "waiting for partitions to "
 980                                 "deactivate/disengage, active count=%d, remote "
 981                                 "engaged=0x%lx\n", active_part_count,
 982                                 xpc_partition_engaged(1UL << partid));
 983
 984                         printmsg_time = jiffies +
 985                                         (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
 986                 }
 987
 988                 /* sleep for a 1/3 of a second or so */
 989                 (void) msleep_interruptible(300);
 990
 991         } while (1);
 992
 993         DBUG_ON(xpc_partition_engaged(-1UL));
 994
 995
 996         /* indicate to others that our reserved page is uninitialized */
 997         xpc_rsvd_page->vars_pa = 0;
 998
 999         /* now it's time to eliminate our heartbeat */
1000         del_timer_sync(&xpc_hb_timer);
1001         DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
1002
1003         /* take ourselves off of the reboot_notifier_list */
1004         (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1005
1006         /* take ourselves off of the die_notifier list */
1007         (void) unregister_die_notifier(&xpc_die_notifier);
1008
1009         /* close down protections for IPI operations */
1010         xpc_restrict_IPI_ops();
1011
1012
1013         /* clear the interface to XPC's functions */
1014         xpc_clear_interface();
1015
1016         if (xpc_sysctl) {
1017                 unregister_sysctl_table(xpc_sysctl);
1018         }
1019 }
1020
1021
1022 /*
1023  * Called when the system is about to be either restarted or halted.
1024  */
1025 static void
1026 xpc_die_disengage(void)
1027 {
1028         struct xpc_partition *part;
1029         partid_t partid;
1030         unsigned long engaged;
1031         long time, print_time, disengage_request_timeout;
1032
1033
1034         /* keep xpc_hb_checker thread from doing anything (just in case) */
1035         xpc_exiting = 1;
1036
1037         xpc_vars->heartbeating_to_mask = 0;  /* indicate we're deactivated */
1038
1039         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1040                 part = &xpc_partitions[partid];
1041
1042                 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
1043                                                         remote_vars_version)) {
1044
1045                         /* just in case it was left set by an earlier XPC */
1046                         xpc_clear_partition_engaged(1UL << partid);
1047                         continue;
1048                 }
1049
1050                 if (xpc_partition_engaged(1UL << partid) ||
1051                                         part->act_state != XPC_P_INACTIVE) {
1052                         xpc_request_partition_disengage(part);
1053                         xpc_mark_partition_disengaged(part);
1054                         xpc_IPI_send_disengage(part);
1055                 }
1056         }
1057
1058         print_time = rtc_time();
1059         disengage_request_timeout = print_time +
1060                 (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1061
1062         /* wait for all other partitions to disengage from us */
1063
1064         while ((engaged = xpc_partition_engaged(-1UL)) &&
1065                         (time = rtc_time()) < disengage_request_timeout) {
1066
1067                 if (time >= print_time) {
1068                         dev_info(xpc_part, "waiting for remote partitions to "
1069                                 "disengage, engaged=0x%lx\n", engaged);
1070                         print_time = time + (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1071                                                 sn_rtc_cycles_per_second);
1072                 }
1073         }
1074         dev_info(xpc_part, "finished waiting for remote partitions to "
1075                                 "disengage, engaged=0x%lx\n", engaged);
1076 }
1077
1078
1079 /*
1080  * This function is called when the system is being rebooted.
1081  */
1082 static int
1083 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1084 {
1085         enum xpc_retval reason;
1086
1087
1088         switch (event) {
1089         case SYS_RESTART:
1090                 reason = xpcSystemReboot;
1091                 break;
1092         case SYS_HALT:
1093                 reason = xpcSystemHalt;
1094                 break;
1095         case SYS_POWER_OFF:
1096                 reason = xpcSystemPoweroff;
1097                 break;
1098         default:
1099                 reason = xpcSystemGoingDown;
1100         }
1101
1102         xpc_do_exit(reason);
1103         return NOTIFY_DONE;
1104 }
1105
1106
1107 /*
1108  * This function is called when the system is being rebooted.
1109  */
1110 static int
1111 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1112 {
1113         switch (event) {
1114         case DIE_MACHINE_RESTART:
1115         case DIE_MACHINE_HALT:
1116                 xpc_die_disengage();
1117                 break;
1118         case DIE_MCA_MONARCH_ENTER:
1119         case DIE_INIT_MONARCH_ENTER:
1120                 xpc_vars->heartbeat++;
1121                 xpc_vars->heartbeat_offline = 1;
1122                 break;
1123         case DIE_MCA_MONARCH_LEAVE:
1124         case DIE_INIT_MONARCH_LEAVE:
1125                 xpc_vars->heartbeat++;
1126                 xpc_vars->heartbeat_offline = 0;
1127                 break;
1128         }
1129
1130         return NOTIFY_DONE;
1131 }
1132
1133
1134 int __init
1135 xpc_init(void)
1136 {
1137         int ret;
1138         partid_t partid;
1139         struct xpc_partition *part;
1140         pid_t pid;
1141
1142
1143         if (!ia64_platform_is("sn2")) {
1144                 return -ENODEV;
1145         }
1146
1147         /*
1148          * xpc_remote_copy_buffer is used as a temporary buffer for bte_copy'ng
1149          * various portions of a partition's reserved page. Its size is based
1150          * on the size of the reserved page header and part_nasids mask. So we
1151          * need to ensure that the other items will fit as well.
1152          */
1153         if (XPC_RP_VARS_SIZE > XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES) {
1154                 dev_err(xpc_part, "xpc_remote_copy_buffer is not big enough\n");
1155                 return -EPERM;
1156         }
1157         DBUG_ON((u64) xpc_remote_copy_buffer !=
1158                                 L1_CACHE_ALIGN((u64) xpc_remote_copy_buffer));
1159
1160         snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1161         snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1162
1163         xpc_sysctl = register_sysctl_table(xpc_sys_dir, 1);
1164
1165         /*
1166          * The first few fields of each entry of xpc_partitions[] need to
1167          * be initialized now so that calls to xpc_connect() and
1168          * xpc_disconnect() can be made prior to the activation of any remote
1169          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1170          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1171          * PARTITION HAS BEEN ACTIVATED.
1172          */
1173         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1174                 part = &xpc_partitions[partid];
1175
1176                 DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
1177
1178                 part->act_IRQ_rcvd = 0;
1179                 spin_lock_init(&part->act_lock);
1180                 part->act_state = XPC_P_INACTIVE;
1181                 XPC_SET_REASON(part, 0, 0);
1182
1183                 init_timer(&part->disengage_request_timer);
1184                 part->disengage_request_timer.function =
1185                                 xpc_timeout_partition_disengage_request;
1186                 part->disengage_request_timer.data = (unsigned long) part;
1187
1188                 part->setup_state = XPC_P_UNSET;
1189                 init_waitqueue_head(&part->teardown_wq);
1190                 atomic_set(&part->references, 0);
1191         }
1192
1193         /*
1194          * Open up protections for IPI operations (and AMO operations on
1195          * Shub 1.1 systems).
1196          */
1197         xpc_allow_IPI_ops();
1198
1199         /*
1200          * Interrupts being processed will increment this atomic variable and
1201          * awaken the heartbeat thread which will process the interrupts.
1202          */
1203         atomic_set(&xpc_act_IRQ_rcvd, 0);
1204
1205         /*
1206          * This is safe to do before the xpc_hb_checker thread has started
1207          * because the handler releases a wait queue.  If an interrupt is
1208          * received before the thread is waiting, it will not go to sleep,
1209          * but rather immediately process the interrupt.
1210          */
1211         ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1212                                                         "xpc hb", NULL);
1213         if (ret != 0) {
1214                 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1215                         "errno=%d\n", -ret);
1216
1217                 xpc_restrict_IPI_ops();
1218
1219                 if (xpc_sysctl) {
1220                         unregister_sysctl_table(xpc_sysctl);
1221                 }
1222                 return -EBUSY;
1223         }
1224
1225         /*
1226          * Fill the partition reserved page with the information needed by
1227          * other partitions to discover we are alive and establish initial
1228          * communications.
1229          */
1230         xpc_rsvd_page = xpc_rsvd_page_init();
1231         if (xpc_rsvd_page == NULL) {
1232                 dev_err(xpc_part, "could not setup our reserved page\n");
1233
1234                 free_irq(SGI_XPC_ACTIVATE, NULL);
1235                 xpc_restrict_IPI_ops();
1236
1237                 if (xpc_sysctl) {
1238                         unregister_sysctl_table(xpc_sysctl);
1239                 }
1240                 return -EBUSY;
1241         }
1242
1243
1244         /* add ourselves to the reboot_notifier_list */
1245         ret = register_reboot_notifier(&xpc_reboot_notifier);
1246         if (ret != 0) {
1247                 dev_warn(xpc_part, "can't register reboot notifier\n");
1248         }
1249
1250         /* add ourselves to the die_notifier list (i.e., ia64die_chain) */
1251         ret = register_die_notifier(&xpc_die_notifier);
1252         if (ret != 0) {
1253                 dev_warn(xpc_part, "can't register die notifier\n");
1254         }
1255
1256
1257         /*
1258          * Set the beating to other partitions into motion.  This is
1259          * the last requirement for other partitions' discovery to
1260          * initiate communications with us.
1261          */
1262         init_timer(&xpc_hb_timer);
1263         xpc_hb_timer.function = xpc_hb_beater;
1264         xpc_hb_beater(0);
1265
1266
1267         /*
1268          * The real work-horse behind xpc.  This processes incoming
1269          * interrupts and monitors remote heartbeats.
1270          */
1271         pid = kernel_thread(xpc_hb_checker, NULL, 0);
1272         if (pid < 0) {
1273                 dev_err(xpc_part, "failed while forking hb check thread\n");
1274
1275                 /* indicate to others that our reserved page is uninitialized */
1276                 xpc_rsvd_page->vars_pa = 0;
1277
1278                 /* take ourselves off of the reboot_notifier_list */
1279                 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1280
1281                 /* take ourselves off of the die_notifier list */
1282                 (void) unregister_die_notifier(&xpc_die_notifier);
1283
1284                 del_timer_sync(&xpc_hb_timer);
1285                 free_irq(SGI_XPC_ACTIVATE, NULL);
1286                 xpc_restrict_IPI_ops();
1287
1288                 if (xpc_sysctl) {
1289                         unregister_sysctl_table(xpc_sysctl);
1290                 }
1291                 return -EBUSY;
1292         }
1293
1294
1295         /*
1296          * Startup a thread that will attempt to discover other partitions to
1297          * activate based on info provided by SAL. This new thread is short
1298          * lived and will exit once discovery is complete.
1299          */
1300         pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
1301         if (pid < 0) {
1302                 dev_err(xpc_part, "failed while forking discovery thread\n");
1303
1304                 /* mark this new thread as a non-starter */
1305                 up(&xpc_discovery_exited);
1306
1307                 xpc_do_exit(xpcUnloading);
1308                 return -EBUSY;
1309         }
1310
1311
1312         /* set the interface to point at XPC's functions */
1313         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1314                           xpc_initiate_allocate, xpc_initiate_send,
1315                           xpc_initiate_send_notify, xpc_initiate_received,
1316                           xpc_initiate_partid_to_nasids);
1317
1318         return 0;
1319 }
1320 module_init(xpc_init);
1321
1322
1323 void __exit
1324 xpc_exit(void)
1325 {
1326         xpc_do_exit(xpcUnloading);
1327 }
1328 module_exit(xpc_exit);
1329
1330
1331 MODULE_AUTHOR("Silicon Graphics, Inc.");
1332 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1333 MODULE_LICENSE("GPL");
1334
1335 module_param(xpc_hb_interval, int, 0);
1336 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1337                 "heartbeat increments.");
1338
1339 module_param(xpc_hb_check_interval, int, 0);
1340 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1341                 "heartbeat checks.");
1342
1343 module_param(xpc_disengage_request_timelimit, int, 0);
1344 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1345                 "for disengage request to complete.");
1346