Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6] / drivers / misc / sgi-xp / xpc_main.c
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (c) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
7  */
8
9 /*
10  * Cross Partition Communication (XPC) support - standard version.
11  *
12  *      XPC provides a message passing capability that crosses partition
13  *      boundaries. This module is made up of two parts:
14  *
15  *          partition   This part detects the presence/absence of other
16  *                      partitions. It provides a heartbeat and monitors
17  *                      the heartbeats of other partitions.
18  *
19  *          channel     This part manages the channels and sends/receives
20  *                      messages across them to/from other partitions.
21  *
22  *      There are a couple of additional functions residing in XP, which
23  *      provide an interface to XPC for its users.
24  *
25  *
26  *      Caveats:
27  *
28  *        . We currently have no way to determine which nasid an IPI came
29  *          from. Thus, xpc_IPI_send() does a remote AMO write followed by
30  *          an IPI. The AMO indicates where data is to be pulled from, so
31  *          after the IPI arrives, the remote partition checks the AMO word.
32  *          The IPI can actually arrive before the AMO however, so other code
33  *          must periodically check for this case. Also, remote AMO operations
34  *          do not reliably time out. Thus we do a remote PIO read solely to
35  *          know whether the remote partition is down and whether we should
36  *          stop sending IPIs to it. This remote PIO read operation is set up
37  *          in a special nofault region so SAL knows to ignore (and cleanup)
38  *          any errors due to the remote AMO write, PIO read, and/or PIO
39  *          write operations.
40  *
41  *          If/when new hardware solves this IPI problem, we should abandon
42  *          the current approach.
43  *
44  */
45
46 #include <linux/kernel.h>
47 #include <linux/module.h>
48 #include <linux/init.h>
49 #include <linux/cache.h>
50 #include <linux/interrupt.h>
51 #include <linux/delay.h>
52 #include <linux/reboot.h>
53 #include <linux/completion.h>
54 #include <linux/kdebug.h>
55 #include <linux/kthread.h>
56 #include <linux/uaccess.h>
57 #include <asm/sn/intr.h>
58 #include <asm/sn/sn_sal.h>
59 #include "xpc.h"
60
61 /* define two XPC debug device structures to be used with dev_dbg() et al */
62
63 struct device_driver xpc_dbg_name = {
64         .name = "xpc"
65 };
66
67 struct device xpc_part_dbg_subname = {
68         .bus_id = {0},          /* set to "part" at xpc_init() time */
69         .driver = &xpc_dbg_name
70 };
71
72 struct device xpc_chan_dbg_subname = {
73         .bus_id = {0},          /* set to "chan" at xpc_init() time */
74         .driver = &xpc_dbg_name
75 };
76
77 struct device *xpc_part = &xpc_part_dbg_subname;
78 struct device *xpc_chan = &xpc_chan_dbg_subname;
79
80 static int xpc_kdebug_ignore;
81
82 /* systune related variables for /proc/sys directories */
83
84 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
85 static int xpc_hb_min_interval = 1;
86 static int xpc_hb_max_interval = 10;
87
88 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
89 static int xpc_hb_check_min_interval = 10;
90 static int xpc_hb_check_max_interval = 120;
91
92 int xpc_disengage_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
93 static int xpc_disengage_request_min_timelimit; /* = 0 */
94 static int xpc_disengage_request_max_timelimit = 120;
95
96 static ctl_table xpc_sys_xpc_hb_dir[] = {
97         {
98          .ctl_name = CTL_UNNUMBERED,
99          .procname = "hb_interval",
100          .data = &xpc_hb_interval,
101          .maxlen = sizeof(int),
102          .mode = 0644,
103          .proc_handler = &proc_dointvec_minmax,
104          .strategy = &sysctl_intvec,
105          .extra1 = &xpc_hb_min_interval,
106          .extra2 = &xpc_hb_max_interval},
107         {
108          .ctl_name = CTL_UNNUMBERED,
109          .procname = "hb_check_interval",
110          .data = &xpc_hb_check_interval,
111          .maxlen = sizeof(int),
112          .mode = 0644,
113          .proc_handler = &proc_dointvec_minmax,
114          .strategy = &sysctl_intvec,
115          .extra1 = &xpc_hb_check_min_interval,
116          .extra2 = &xpc_hb_check_max_interval},
117         {}
118 };
119 static ctl_table xpc_sys_xpc_dir[] = {
120         {
121          .ctl_name = CTL_UNNUMBERED,
122          .procname = "hb",
123          .mode = 0555,
124          .child = xpc_sys_xpc_hb_dir},
125         {
126          .ctl_name = CTL_UNNUMBERED,
127          .procname = "disengage_request_timelimit",
128          .data = &xpc_disengage_request_timelimit,
129          .maxlen = sizeof(int),
130          .mode = 0644,
131          .proc_handler = &proc_dointvec_minmax,
132          .strategy = &sysctl_intvec,
133          .extra1 = &xpc_disengage_request_min_timelimit,
134          .extra2 = &xpc_disengage_request_max_timelimit},
135         {}
136 };
137 static ctl_table xpc_sys_dir[] = {
138         {
139          .ctl_name = CTL_UNNUMBERED,
140          .procname = "xpc",
141          .mode = 0555,
142          .child = xpc_sys_xpc_dir},
143         {}
144 };
145 static struct ctl_table_header *xpc_sysctl;
146
147 /* non-zero if any remote partition disengage request was timed out */
148 int xpc_disengage_request_timedout;
149
150 /* #of IRQs received */
151 static atomic_t xpc_act_IRQ_rcvd;
152
153 /* IRQ handler notifies this wait queue on receipt of an IRQ */
154 static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
155
156 static unsigned long xpc_hb_check_timeout;
157
158 /* notification that the xpc_hb_checker thread has exited */
159 static DECLARE_COMPLETION(xpc_hb_checker_exited);
160
161 /* notification that the xpc_discovery thread has exited */
162 static DECLARE_COMPLETION(xpc_discovery_exited);
163
164 static struct timer_list xpc_hb_timer;
165
166 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
167
168 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
169 static struct notifier_block xpc_reboot_notifier = {
170         .notifier_call = xpc_system_reboot,
171 };
172
173 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
174 static struct notifier_block xpc_die_notifier = {
175         .notifier_call = xpc_system_die,
176 };
177
178 /*
179  * Timer function to enforce the timelimit on the partition disengage request.
180  */
181 static void
182 xpc_timeout_partition_disengage_request(unsigned long data)
183 {
184         struct xpc_partition *part = (struct xpc_partition *)data;
185
186         DBUG_ON(time_before(jiffies, part->disengage_request_timeout));
187
188         (void)xpc_partition_disengaged(part);
189
190         DBUG_ON(part->disengage_request_timeout != 0);
191         DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
192 }
193
194 /*
195  * Notify the heartbeat check thread that an IRQ has been received.
196  */
197 static irqreturn_t
198 xpc_act_IRQ_handler(int irq, void *dev_id)
199 {
200         atomic_inc(&xpc_act_IRQ_rcvd);
201         wake_up_interruptible(&xpc_act_IRQ_wq);
202         return IRQ_HANDLED;
203 }
204
205 /*
206  * Timer to produce the heartbeat.  The timer structures function is
207  * already set when this is initially called.  A tunable is used to
208  * specify when the next timeout should occur.
209  */
210 static void
211 xpc_hb_beater(unsigned long dummy)
212 {
213         xpc_vars->heartbeat++;
214
215         if (time_after_eq(jiffies, xpc_hb_check_timeout))
216                 wake_up_interruptible(&xpc_act_IRQ_wq);
217
218         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
219         add_timer(&xpc_hb_timer);
220 }
221
222 /*
223  * This thread is responsible for nearly all of the partition
224  * activation/deactivation.
225  */
226 static int
227 xpc_hb_checker(void *ignore)
228 {
229         int last_IRQ_count = 0;
230         int new_IRQ_count;
231         int force_IRQ = 0;
232         cpumask_of_cpu_ptr(cpumask, XPC_HB_CHECK_CPU);
233
234         /* this thread was marked active by xpc_hb_init() */
235
236         set_cpus_allowed_ptr(current, cpumask);
237
238         /* set our heartbeating to other partitions into motion */
239         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
240         xpc_hb_beater(0);
241
242         while (!xpc_exiting) {
243
244                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
245                         "been received\n",
246                         (int)(xpc_hb_check_timeout - jiffies),
247                         atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
248
249                 /* checking of remote heartbeats is skewed by IRQ handling */
250                 if (time_after_eq(jiffies, xpc_hb_check_timeout)) {
251                         dev_dbg(xpc_part, "checking remote heartbeats\n");
252                         xpc_check_remote_hb();
253
254                         /*
255                          * We need to periodically recheck to ensure no
256                          * IPI/AMO pairs have been missed.  That check
257                          * must always reset xpc_hb_check_timeout.
258                          */
259                         force_IRQ = 1;
260                 }
261
262                 /* check for outstanding IRQs */
263                 new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
264                 if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
265                         force_IRQ = 0;
266
267                         dev_dbg(xpc_part, "found an IRQ to process; will be "
268                                 "resetting xpc_hb_check_timeout\n");
269
270                         last_IRQ_count += xpc_identify_act_IRQ_sender();
271                         if (last_IRQ_count < new_IRQ_count) {
272                                 /* retry once to help avoid missing AMO */
273                                 (void)xpc_identify_act_IRQ_sender();
274                         }
275                         last_IRQ_count = new_IRQ_count;
276
277                         xpc_hb_check_timeout = jiffies +
278                             (xpc_hb_check_interval * HZ);
279                 }
280
281                 /* wait for IRQ or timeout */
282                 (void)wait_event_interruptible(xpc_act_IRQ_wq,
283                                                (last_IRQ_count <
284                                                 atomic_read(&xpc_act_IRQ_rcvd)
285                                                 || time_after_eq(jiffies,
286                                                         xpc_hb_check_timeout) ||
287                                                 xpc_exiting));
288         }
289
290         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
291
292         /* mark this thread as having exited */
293         complete(&xpc_hb_checker_exited);
294         return 0;
295 }
296
297 /*
298  * This thread will attempt to discover other partitions to activate
299  * based on info provided by SAL. This new thread is short lived and
300  * will exit once discovery is complete.
301  */
302 static int
303 xpc_initiate_discovery(void *ignore)
304 {
305         xpc_discovery();
306
307         dev_dbg(xpc_part, "discovery thread is exiting\n");
308
309         /* mark this thread as having exited */
310         complete(&xpc_discovery_exited);
311         return 0;
312 }
313
314 /*
315  * Establish first contact with the remote partititon. This involves pulling
316  * the XPC per partition variables from the remote partition and waiting for
317  * the remote partition to pull ours.
318  */
319 static enum xp_retval
320 xpc_make_first_contact(struct xpc_partition *part)
321 {
322         enum xp_retval ret;
323
324         while ((ret = xpc_pull_remote_vars_part(part)) != xpSuccess) {
325                 if (ret != xpRetry) {
326                         XPC_DEACTIVATE_PARTITION(part, ret);
327                         return ret;
328                 }
329
330                 dev_dbg(xpc_chan, "waiting to make first contact with "
331                         "partition %d\n", XPC_PARTID(part));
332
333                 /* wait a 1/4 of a second or so */
334                 (void)msleep_interruptible(250);
335
336                 if (part->act_state == XPC_P_DEACTIVATING)
337                         return part->reason;
338         }
339
340         return xpc_mark_partition_active(part);
341 }
342
343 /*
344  * The first kthread assigned to a newly activated partition is the one
345  * created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
346  * that kthread until the partition is brought down, at which time that kthread
347  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
348  * that XPC has dismantled all communication infrastructure for the associated
349  * partition.) This kthread becomes the channel manager for that partition.
350  *
351  * Each active partition has a channel manager, who, besides connecting and
352  * disconnecting channels, will ensure that each of the partition's connected
353  * channels has the required number of assigned kthreads to get the work done.
354  */
355 static void
356 xpc_channel_mgr(struct xpc_partition *part)
357 {
358         while (part->act_state != XPC_P_DEACTIVATING ||
359                atomic_read(&part->nchannels_active) > 0 ||
360                !xpc_partition_disengaged(part)) {
361
362                 xpc_process_channel_activity(part);
363
364                 /*
365                  * Wait until we've been requested to activate kthreads or
366                  * all of the channel's message queues have been torn down or
367                  * a signal is pending.
368                  *
369                  * The channel_mgr_requests is set to 1 after being awakened,
370                  * This is done to prevent the channel mgr from making one pass
371                  * through the loop for each request, since he will
372                  * be servicing all the requests in one pass. The reason it's
373                  * set to 1 instead of 0 is so that other kthreads will know
374                  * that the channel mgr is running and won't bother trying to
375                  * wake him up.
376                  */
377                 atomic_dec(&part->channel_mgr_requests);
378                 (void)wait_event_interruptible(part->channel_mgr_wq,
379                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
380                                  part->local_IPI_amo != 0 ||
381                                  (part->act_state == XPC_P_DEACTIVATING &&
382                                  atomic_read(&part->nchannels_active) == 0 &&
383                                  xpc_partition_disengaged(part))));
384                 atomic_set(&part->channel_mgr_requests, 1);
385         }
386 }
387
388 /*
389  * When XPC HB determines that a partition has come up, it will create a new
390  * kthread and that kthread will call this function to attempt to set up the
391  * basic infrastructure used for Cross Partition Communication with the newly
392  * upped partition.
393  *
394  * The kthread that was created by XPC HB and which setup the XPC
395  * infrastructure will remain assigned to the partition until the partition
396  * goes down. At which time the kthread will teardown the XPC infrastructure
397  * and then exit.
398  *
399  * XPC HB will put the remote partition's XPC per partition specific variables
400  * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
401  * calling xpc_partition_up().
402  */
403 static void
404 xpc_partition_up(struct xpc_partition *part)
405 {
406         DBUG_ON(part->channels != NULL);
407
408         dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
409
410         if (xpc_setup_infrastructure(part) != xpSuccess)
411                 return;
412
413         /*
414          * The kthread that XPC HB called us with will become the
415          * channel manager for this partition. It will not return
416          * back to XPC HB until the partition's XPC infrastructure
417          * has been dismantled.
418          */
419
420         (void)xpc_part_ref(part);       /* this will always succeed */
421
422         if (xpc_make_first_contact(part) == xpSuccess)
423                 xpc_channel_mgr(part);
424
425         xpc_part_deref(part);
426
427         xpc_teardown_infrastructure(part);
428 }
429
430 static int
431 xpc_activating(void *__partid)
432 {
433         short partid = (u64)__partid;
434         struct xpc_partition *part = &xpc_partitions[partid];
435         unsigned long irq_flags;
436
437         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
438
439         spin_lock_irqsave(&part->act_lock, irq_flags);
440
441         if (part->act_state == XPC_P_DEACTIVATING) {
442                 part->act_state = XPC_P_INACTIVE;
443                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
444                 part->remote_rp_pa = 0;
445                 return 0;
446         }
447
448         /* indicate the thread is activating */
449         DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
450         part->act_state = XPC_P_ACTIVATING;
451
452         XPC_SET_REASON(part, 0, 0);
453         spin_unlock_irqrestore(&part->act_lock, irq_flags);
454
455         dev_dbg(xpc_part, "bringing partition %d up\n", partid);
456
457         /*
458          * Register the remote partition's AMOs with SAL so it can handle
459          * and cleanup errors within that address range should the remote
460          * partition go down. We don't unregister this range because it is
461          * difficult to tell when outstanding writes to the remote partition
462          * are finished and thus when it is safe to unregister. This should
463          * not result in wasted space in the SAL xp_addr_region table because
464          * we should get the same page for remote_amos_page_pa after module
465          * reloads and system reboots.
466          */
467         if (sn_register_xp_addr_region(part->remote_amos_page_pa,
468                                        PAGE_SIZE, 1) < 0) {
469                 dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
470                          "xp_addr region\n", partid);
471
472                 spin_lock_irqsave(&part->act_lock, irq_flags);
473                 part->act_state = XPC_P_INACTIVE;
474                 XPC_SET_REASON(part, xpPhysAddrRegFailed, __LINE__);
475                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
476                 part->remote_rp_pa = 0;
477                 return 0;
478         }
479
480         xpc_allow_hb(partid, xpc_vars);
481         xpc_IPI_send_activated(part);
482
483         /*
484          * xpc_partition_up() holds this thread and marks this partition as
485          * XPC_P_ACTIVE by calling xpc_hb_mark_active().
486          */
487         (void)xpc_partition_up(part);
488
489         xpc_disallow_hb(partid, xpc_vars);
490         xpc_mark_partition_inactive(part);
491
492         if (part->reason == xpReactivating) {
493                 /* interrupting ourselves results in activating partition */
494                 xpc_IPI_send_reactivate(part);
495         }
496
497         return 0;
498 }
499
500 void
501 xpc_activate_partition(struct xpc_partition *part)
502 {
503         short partid = XPC_PARTID(part);
504         unsigned long irq_flags;
505         struct task_struct *kthread;
506
507         spin_lock_irqsave(&part->act_lock, irq_flags);
508
509         DBUG_ON(part->act_state != XPC_P_INACTIVE);
510
511         part->act_state = XPC_P_ACTIVATION_REQ;
512         XPC_SET_REASON(part, xpCloneKThread, __LINE__);
513
514         spin_unlock_irqrestore(&part->act_lock, irq_flags);
515
516         kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
517                               partid);
518         if (IS_ERR(kthread)) {
519                 spin_lock_irqsave(&part->act_lock, irq_flags);
520                 part->act_state = XPC_P_INACTIVE;
521                 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
522                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
523         }
524 }
525
526 /*
527  * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
528  * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
529  * than one partition, we use an AMO_t structure per partition to indicate
530  * whether a partition has sent an IPI or not.  If it has, then wake up the
531  * associated kthread to handle it.
532  *
533  * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
534  * running on other partitions.
535  *
536  * Noteworthy Arguments:
537  *
538  *      irq - Interrupt ReQuest number. NOT USED.
539  *
540  *      dev_id - partid of IPI's potential sender.
541  */
542 irqreturn_t
543 xpc_notify_IRQ_handler(int irq, void *dev_id)
544 {
545         short partid = (short)(u64)dev_id;
546         struct xpc_partition *part = &xpc_partitions[partid];
547
548         DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
549
550         if (xpc_part_ref(part)) {
551                 xpc_check_for_channel_activity(part);
552
553                 xpc_part_deref(part);
554         }
555         return IRQ_HANDLED;
556 }
557
558 /*
559  * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
560  * because the write to their associated IPI amo completed after the IRQ/IPI
561  * was received.
562  */
563 void
564 xpc_dropped_IPI_check(struct xpc_partition *part)
565 {
566         if (xpc_part_ref(part)) {
567                 xpc_check_for_channel_activity(part);
568
569                 part->dropped_IPI_timer.expires = jiffies +
570                     XPC_P_DROPPED_IPI_WAIT;
571                 add_timer(&part->dropped_IPI_timer);
572                 xpc_part_deref(part);
573         }
574 }
575
576 void
577 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
578 {
579         int idle = atomic_read(&ch->kthreads_idle);
580         int assigned = atomic_read(&ch->kthreads_assigned);
581         int wakeup;
582
583         DBUG_ON(needed <= 0);
584
585         if (idle > 0) {
586                 wakeup = (needed > idle) ? idle : needed;
587                 needed -= wakeup;
588
589                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
590                         "channel=%d\n", wakeup, ch->partid, ch->number);
591
592                 /* only wakeup the requested number of kthreads */
593                 wake_up_nr(&ch->idle_wq, wakeup);
594         }
595
596         if (needed <= 0)
597                 return;
598
599         if (needed + assigned > ch->kthreads_assigned_limit) {
600                 needed = ch->kthreads_assigned_limit - assigned;
601                 if (needed <= 0)
602                         return;
603         }
604
605         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
606                 needed, ch->partid, ch->number);
607
608         xpc_create_kthreads(ch, needed, 0);
609 }
610
611 /*
612  * This function is where XPC's kthreads wait for messages to deliver.
613  */
614 static void
615 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
616 {
617         do {
618                 /* deliver messages to their intended recipients */
619
620                 while (ch->w_local_GP.get < ch->w_remote_GP.put &&
621                        !(ch->flags & XPC_C_DISCONNECTING)) {
622                         xpc_deliver_msg(ch);
623                 }
624
625                 if (atomic_inc_return(&ch->kthreads_idle) >
626                     ch->kthreads_idle_limit) {
627                         /* too many idle kthreads on this channel */
628                         atomic_dec(&ch->kthreads_idle);
629                         break;
630                 }
631
632                 dev_dbg(xpc_chan, "idle kthread calling "
633                         "wait_event_interruptible_exclusive()\n");
634
635                 (void)wait_event_interruptible_exclusive(ch->idle_wq,
636                                 (ch->w_local_GP.get < ch->w_remote_GP.put ||
637                                  (ch->flags & XPC_C_DISCONNECTING)));
638
639                 atomic_dec(&ch->kthreads_idle);
640
641         } while (!(ch->flags & XPC_C_DISCONNECTING));
642 }
643
644 static int
645 xpc_kthread_start(void *args)
646 {
647         short partid = XPC_UNPACK_ARG1(args);
648         u16 ch_number = XPC_UNPACK_ARG2(args);
649         struct xpc_partition *part = &xpc_partitions[partid];
650         struct xpc_channel *ch;
651         int n_needed;
652         unsigned long irq_flags;
653
654         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
655                 partid, ch_number);
656
657         ch = &part->channels[ch_number];
658
659         if (!(ch->flags & XPC_C_DISCONNECTING)) {
660
661                 /* let registerer know that connection has been established */
662
663                 spin_lock_irqsave(&ch->lock, irq_flags);
664                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
665                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
666                         spin_unlock_irqrestore(&ch->lock, irq_flags);
667
668                         xpc_connected_callout(ch);
669
670                         spin_lock_irqsave(&ch->lock, irq_flags);
671                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
672                         spin_unlock_irqrestore(&ch->lock, irq_flags);
673
674                         /*
675                          * It is possible that while the callout was being
676                          * made that the remote partition sent some messages.
677                          * If that is the case, we may need to activate
678                          * additional kthreads to help deliver them. We only
679                          * need one less than total #of messages to deliver.
680                          */
681                         n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
682                         if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
683                                 xpc_activate_kthreads(ch, n_needed);
684
685                 } else {
686                         spin_unlock_irqrestore(&ch->lock, irq_flags);
687                 }
688
689                 xpc_kthread_waitmsgs(part, ch);
690         }
691
692         /* let registerer know that connection is disconnecting */
693
694         spin_lock_irqsave(&ch->lock, irq_flags);
695         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
696             !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
697                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
698                 spin_unlock_irqrestore(&ch->lock, irq_flags);
699
700                 xpc_disconnect_callout(ch, xpDisconnecting);
701
702                 spin_lock_irqsave(&ch->lock, irq_flags);
703                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
704         }
705         spin_unlock_irqrestore(&ch->lock, irq_flags);
706
707         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
708                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
709                         xpc_mark_partition_disengaged(part);
710                         xpc_IPI_send_disengage(part);
711                 }
712         }
713
714         xpc_msgqueue_deref(ch);
715
716         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
717                 partid, ch_number);
718
719         xpc_part_deref(part);
720         return 0;
721 }
722
723 /*
724  * For each partition that XPC has established communications with, there is
725  * a minimum of one kernel thread assigned to perform any operation that
726  * may potentially sleep or block (basically the callouts to the asynchronous
727  * functions registered via xpc_connect()).
728  *
729  * Additional kthreads are created and destroyed by XPC as the workload
730  * demands.
731  *
732  * A kthread is assigned to one of the active channels that exists for a given
733  * partition.
734  */
735 void
736 xpc_create_kthreads(struct xpc_channel *ch, int needed,
737                     int ignore_disconnecting)
738 {
739         unsigned long irq_flags;
740         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
741         struct xpc_partition *part = &xpc_partitions[ch->partid];
742         struct task_struct *kthread;
743
744         while (needed-- > 0) {
745
746                 /*
747                  * The following is done on behalf of the newly created
748                  * kthread. That kthread is responsible for doing the
749                  * counterpart to the following before it exits.
750                  */
751                 if (ignore_disconnecting) {
752                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
753                                 /* kthreads assigned had gone to zero */
754                                 BUG_ON(!(ch->flags &
755                                          XPC_C_DISCONNECTINGCALLOUT_MADE));
756                                 break;
757                         }
758
759                 } else if (ch->flags & XPC_C_DISCONNECTING) {
760                         break;
761
762                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1) {
763                         if (atomic_inc_return(&part->nchannels_engaged) == 1)
764                                 xpc_mark_partition_engaged(part);
765                 }
766                 (void)xpc_part_ref(part);
767                 xpc_msgqueue_ref(ch);
768
769                 kthread = kthread_run(xpc_kthread_start, (void *)args,
770                                       "xpc%02dc%d", ch->partid, ch->number);
771                 if (IS_ERR(kthread)) {
772                         /* the fork failed */
773
774                         /*
775                          * NOTE: if (ignore_disconnecting &&
776                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
777                          * then we'll deadlock if all other kthreads assigned
778                          * to this channel are blocked in the channel's
779                          * registerer, because the only thing that will unblock
780                          * them is the xpDisconnecting callout that this
781                          * failed kthread_run() would have made.
782                          */
783
784                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
785                             atomic_dec_return(&part->nchannels_engaged) == 0) {
786                                 xpc_mark_partition_disengaged(part);
787                                 xpc_IPI_send_disengage(part);
788                         }
789                         xpc_msgqueue_deref(ch);
790                         xpc_part_deref(part);
791
792                         if (atomic_read(&ch->kthreads_assigned) <
793                             ch->kthreads_idle_limit) {
794                                 /*
795                                  * Flag this as an error only if we have an
796                                  * insufficient #of kthreads for the channel
797                                  * to function.
798                                  */
799                                 spin_lock_irqsave(&ch->lock, irq_flags);
800                                 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
801                                                        &irq_flags);
802                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
803                         }
804                         break;
805                 }
806         }
807 }
808
809 void
810 xpc_disconnect_wait(int ch_number)
811 {
812         unsigned long irq_flags;
813         short partid;
814         struct xpc_partition *part;
815         struct xpc_channel *ch;
816         int wakeup_channel_mgr;
817
818         /* now wait for all callouts to the caller's function to cease */
819         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
820                 part = &xpc_partitions[partid];
821
822                 if (!xpc_part_ref(part))
823                         continue;
824
825                 ch = &part->channels[ch_number];
826
827                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
828                         xpc_part_deref(part);
829                         continue;
830                 }
831
832                 wait_for_completion(&ch->wdisconnect_wait);
833
834                 spin_lock_irqsave(&ch->lock, irq_flags);
835                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
836                 wakeup_channel_mgr = 0;
837
838                 if (ch->delayed_IPI_flags) {
839                         if (part->act_state != XPC_P_DEACTIVATING) {
840                                 spin_lock(&part->IPI_lock);
841                                 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
842                                                   ch->number,
843                                                   ch->delayed_IPI_flags);
844                                 spin_unlock(&part->IPI_lock);
845                                 wakeup_channel_mgr = 1;
846                         }
847                         ch->delayed_IPI_flags = 0;
848                 }
849
850                 ch->flags &= ~XPC_C_WDISCONNECT;
851                 spin_unlock_irqrestore(&ch->lock, irq_flags);
852
853                 if (wakeup_channel_mgr)
854                         xpc_wakeup_channel_mgr(part);
855
856                 xpc_part_deref(part);
857         }
858 }
859
860 static void
861 xpc_do_exit(enum xp_retval reason)
862 {
863         short partid;
864         int active_part_count, printed_waiting_msg = 0;
865         struct xpc_partition *part;
866         unsigned long printmsg_time, disengage_request_timeout = 0;
867
868         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
869         DBUG_ON(xpc_exiting == 1);
870
871         /*
872          * Let the heartbeat checker thread and the discovery thread
873          * (if one is running) know that they should exit. Also wake up
874          * the heartbeat checker thread in case it's sleeping.
875          */
876         xpc_exiting = 1;
877         wake_up_interruptible(&xpc_act_IRQ_wq);
878
879         /* ignore all incoming interrupts */
880         free_irq(SGI_XPC_ACTIVATE, NULL);
881
882         /* wait for the discovery thread to exit */
883         wait_for_completion(&xpc_discovery_exited);
884
885         /* wait for the heartbeat checker thread to exit */
886         wait_for_completion(&xpc_hb_checker_exited);
887
888         /* sleep for a 1/3 of a second or so */
889         (void)msleep_interruptible(300);
890
891         /* wait for all partitions to become inactive */
892
893         printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
894         xpc_disengage_request_timedout = 0;
895
896         do {
897                 active_part_count = 0;
898
899                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
900                         part = &xpc_partitions[partid];
901
902                         if (xpc_partition_disengaged(part) &&
903                             part->act_state == XPC_P_INACTIVE) {
904                                 continue;
905                         }
906
907                         active_part_count++;
908
909                         XPC_DEACTIVATE_PARTITION(part, reason);
910
911                         if (part->disengage_request_timeout >
912                             disengage_request_timeout) {
913                                 disengage_request_timeout =
914                                     part->disengage_request_timeout;
915                         }
916                 }
917
918                 if (xpc_partition_engaged(-1UL)) {
919                         if (time_after(jiffies, printmsg_time)) {
920                                 dev_info(xpc_part, "waiting for remote "
921                                          "partitions to disengage, timeout in "
922                                          "%ld seconds\n",
923                                          (disengage_request_timeout - jiffies)
924                                          / HZ);
925                                 printmsg_time = jiffies +
926                                     (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
927                                 printed_waiting_msg = 1;
928                         }
929
930                 } else if (active_part_count > 0) {
931                         if (printed_waiting_msg) {
932                                 dev_info(xpc_part, "waiting for local partition"
933                                          " to disengage\n");
934                                 printed_waiting_msg = 0;
935                         }
936
937                 } else {
938                         if (!xpc_disengage_request_timedout) {
939                                 dev_info(xpc_part, "all partitions have "
940                                          "disengaged\n");
941                         }
942                         break;
943                 }
944
945                 /* sleep for a 1/3 of a second or so */
946                 (void)msleep_interruptible(300);
947
948         } while (1);
949
950         DBUG_ON(xpc_partition_engaged(-1UL));
951
952         /* indicate to others that our reserved page is uninitialized */
953         xpc_rsvd_page->vars_pa = 0;
954
955         /* now it's time to eliminate our heartbeat */
956         del_timer_sync(&xpc_hb_timer);
957         DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
958
959         if (reason == xpUnloading) {
960                 /* take ourselves off of the reboot_notifier_list */
961                 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
962
963                 /* take ourselves off of the die_notifier list */
964                 (void)unregister_die_notifier(&xpc_die_notifier);
965         }
966
967         /* close down protections for IPI operations */
968         xpc_restrict_IPI_ops();
969
970         /* clear the interface to XPC's functions */
971         xpc_clear_interface();
972
973         if (xpc_sysctl)
974                 unregister_sysctl_table(xpc_sysctl);
975
976         kfree(xpc_remote_copy_buffer_base);
977 }
978
979 /*
980  * This function is called when the system is being rebooted.
981  */
982 static int
983 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
984 {
985         enum xp_retval reason;
986
987         switch (event) {
988         case SYS_RESTART:
989                 reason = xpSystemReboot;
990                 break;
991         case SYS_HALT:
992                 reason = xpSystemHalt;
993                 break;
994         case SYS_POWER_OFF:
995                 reason = xpSystemPoweroff;
996                 break;
997         default:
998                 reason = xpSystemGoingDown;
999         }
1000
1001         xpc_do_exit(reason);
1002         return NOTIFY_DONE;
1003 }
1004
1005 /*
1006  * Notify other partitions to disengage from all references to our memory.
1007  */
1008 static void
1009 xpc_die_disengage(void)
1010 {
1011         struct xpc_partition *part;
1012         short partid;
1013         unsigned long engaged;
1014         long time, printmsg_time, disengage_request_timeout;
1015
1016         /* keep xpc_hb_checker thread from doing anything (just in case) */
1017         xpc_exiting = 1;
1018
1019         xpc_vars->heartbeating_to_mask = 0;     /* indicate we're deactivated */
1020
1021         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1022                 part = &xpc_partitions[partid];
1023
1024                 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
1025                     remote_vars_version)) {
1026
1027                         /* just in case it was left set by an earlier XPC */
1028                         xpc_clear_partition_engaged(1UL << partid);
1029                         continue;
1030                 }
1031
1032                 if (xpc_partition_engaged(1UL << partid) ||
1033                     part->act_state != XPC_P_INACTIVE) {
1034                         xpc_request_partition_disengage(part);
1035                         xpc_mark_partition_disengaged(part);
1036                         xpc_IPI_send_disengage(part);
1037                 }
1038         }
1039
1040         time = rtc_time();
1041         printmsg_time = time +
1042             (XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
1043         disengage_request_timeout = time +
1044             (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1045
1046         /* wait for all other partitions to disengage from us */
1047
1048         while (1) {
1049                 engaged = xpc_partition_engaged(-1UL);
1050                 if (!engaged) {
1051                         dev_info(xpc_part, "all partitions have disengaged\n");
1052                         break;
1053                 }
1054
1055                 time = rtc_time();
1056                 if (time >= disengage_request_timeout) {
1057                         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1058                                 if (engaged & (1UL << partid)) {
1059                                         dev_info(xpc_part, "disengage from "
1060                                                  "remote partition %d timed "
1061                                                  "out\n", partid);
1062                                 }
1063                         }
1064                         break;
1065                 }
1066
1067                 if (time >= printmsg_time) {
1068                         dev_info(xpc_part, "waiting for remote partitions to "
1069                                  "disengage, timeout in %ld seconds\n",
1070                                  (disengage_request_timeout - time) /
1071                                  sn_rtc_cycles_per_second);
1072                         printmsg_time = time +
1073                             (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1074                              sn_rtc_cycles_per_second);
1075                 }
1076         }
1077 }
1078
1079 /*
1080  * This function is called when the system is being restarted or halted due
1081  * to some sort of system failure. If this is the case we need to notify the
1082  * other partitions to disengage from all references to our memory.
1083  * This function can also be called when our heartbeater could be offlined
1084  * for a time. In this case we need to notify other partitions to not worry
1085  * about the lack of a heartbeat.
1086  */
1087 static int
1088 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1089 {
1090         switch (event) {
1091         case DIE_MACHINE_RESTART:
1092         case DIE_MACHINE_HALT:
1093                 xpc_die_disengage();
1094                 break;
1095
1096         case DIE_KDEBUG_ENTER:
1097                 /* Should lack of heartbeat be ignored by other partitions? */
1098                 if (!xpc_kdebug_ignore)
1099                         break;
1100
1101                 /* fall through */
1102         case DIE_MCA_MONARCH_ENTER:
1103         case DIE_INIT_MONARCH_ENTER:
1104                 xpc_vars->heartbeat++;
1105                 xpc_vars->heartbeat_offline = 1;
1106                 break;
1107
1108         case DIE_KDEBUG_LEAVE:
1109                 /* Is lack of heartbeat being ignored by other partitions? */
1110                 if (!xpc_kdebug_ignore)
1111                         break;
1112
1113                 /* fall through */
1114         case DIE_MCA_MONARCH_LEAVE:
1115         case DIE_INIT_MONARCH_LEAVE:
1116                 xpc_vars->heartbeat++;
1117                 xpc_vars->heartbeat_offline = 0;
1118                 break;
1119         }
1120
1121         return NOTIFY_DONE;
1122 }
1123
1124 int __init
1125 xpc_init(void)
1126 {
1127         int ret;
1128         short partid;
1129         struct xpc_partition *part;
1130         struct task_struct *kthread;
1131         size_t buf_size;
1132
1133         if (!ia64_platform_is("sn2"))
1134                 return -ENODEV;
1135
1136         buf_size = max(XPC_RP_VARS_SIZE,
1137                        XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES);
1138         xpc_remote_copy_buffer = xpc_kmalloc_cacheline_aligned(buf_size,
1139                                                                GFP_KERNEL,
1140                                                   &xpc_remote_copy_buffer_base);
1141         if (xpc_remote_copy_buffer == NULL)
1142                 return -ENOMEM;
1143
1144         snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1145         snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1146
1147         xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1148
1149         /*
1150          * The first few fields of each entry of xpc_partitions[] need to
1151          * be initialized now so that calls to xpc_connect() and
1152          * xpc_disconnect() can be made prior to the activation of any remote
1153          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1154          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1155          * PARTITION HAS BEEN ACTIVATED.
1156          */
1157         for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1158                 part = &xpc_partitions[partid];
1159
1160                 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
1161
1162                 part->act_IRQ_rcvd = 0;
1163                 spin_lock_init(&part->act_lock);
1164                 part->act_state = XPC_P_INACTIVE;
1165                 XPC_SET_REASON(part, 0, 0);
1166
1167                 init_timer(&part->disengage_request_timer);
1168                 part->disengage_request_timer.function =
1169                     xpc_timeout_partition_disengage_request;
1170                 part->disengage_request_timer.data = (unsigned long)part;
1171
1172                 part->setup_state = XPC_P_UNSET;
1173                 init_waitqueue_head(&part->teardown_wq);
1174                 atomic_set(&part->references, 0);
1175         }
1176
1177         /*
1178          * Open up protections for IPI operations (and AMO operations on
1179          * Shub 1.1 systems).
1180          */
1181         xpc_allow_IPI_ops();
1182
1183         /*
1184          * Interrupts being processed will increment this atomic variable and
1185          * awaken the heartbeat thread which will process the interrupts.
1186          */
1187         atomic_set(&xpc_act_IRQ_rcvd, 0);
1188
1189         /*
1190          * This is safe to do before the xpc_hb_checker thread has started
1191          * because the handler releases a wait queue.  If an interrupt is
1192          * received before the thread is waiting, it will not go to sleep,
1193          * but rather immediately process the interrupt.
1194          */
1195         ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1196                           "xpc hb", NULL);
1197         if (ret != 0) {
1198                 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1199                         "errno=%d\n", -ret);
1200
1201                 xpc_restrict_IPI_ops();
1202
1203                 if (xpc_sysctl)
1204                         unregister_sysctl_table(xpc_sysctl);
1205
1206                 kfree(xpc_remote_copy_buffer_base);
1207                 return -EBUSY;
1208         }
1209
1210         /*
1211          * Fill the partition reserved page with the information needed by
1212          * other partitions to discover we are alive and establish initial
1213          * communications.
1214          */
1215         xpc_rsvd_page = xpc_rsvd_page_init();
1216         if (xpc_rsvd_page == NULL) {
1217                 dev_err(xpc_part, "could not setup our reserved page\n");
1218
1219                 free_irq(SGI_XPC_ACTIVATE, NULL);
1220                 xpc_restrict_IPI_ops();
1221
1222                 if (xpc_sysctl)
1223                         unregister_sysctl_table(xpc_sysctl);
1224
1225                 kfree(xpc_remote_copy_buffer_base);
1226                 return -EBUSY;
1227         }
1228
1229         /* add ourselves to the reboot_notifier_list */
1230         ret = register_reboot_notifier(&xpc_reboot_notifier);
1231         if (ret != 0)
1232                 dev_warn(xpc_part, "can't register reboot notifier\n");
1233
1234         /* add ourselves to the die_notifier list */
1235         ret = register_die_notifier(&xpc_die_notifier);
1236         if (ret != 0)
1237                 dev_warn(xpc_part, "can't register die notifier\n");
1238
1239         init_timer(&xpc_hb_timer);
1240         xpc_hb_timer.function = xpc_hb_beater;
1241
1242         /*
1243          * The real work-horse behind xpc.  This processes incoming
1244          * interrupts and monitors remote heartbeats.
1245          */
1246         kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1247         if (IS_ERR(kthread)) {
1248                 dev_err(xpc_part, "failed while forking hb check thread\n");
1249
1250                 /* indicate to others that our reserved page is uninitialized */
1251                 xpc_rsvd_page->vars_pa = 0;
1252
1253                 /* take ourselves off of the reboot_notifier_list */
1254                 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1255
1256                 /* take ourselves off of the die_notifier list */
1257                 (void)unregister_die_notifier(&xpc_die_notifier);
1258
1259                 del_timer_sync(&xpc_hb_timer);
1260                 free_irq(SGI_XPC_ACTIVATE, NULL);
1261                 xpc_restrict_IPI_ops();
1262
1263                 if (xpc_sysctl)
1264                         unregister_sysctl_table(xpc_sysctl);
1265
1266                 kfree(xpc_remote_copy_buffer_base);
1267                 return -EBUSY;
1268         }
1269
1270         /*
1271          * Startup a thread that will attempt to discover other partitions to
1272          * activate based on info provided by SAL. This new thread is short
1273          * lived and will exit once discovery is complete.
1274          */
1275         kthread = kthread_run(xpc_initiate_discovery, NULL,
1276                               XPC_DISCOVERY_THREAD_NAME);
1277         if (IS_ERR(kthread)) {
1278                 dev_err(xpc_part, "failed while forking discovery thread\n");
1279
1280                 /* mark this new thread as a non-starter */
1281                 complete(&xpc_discovery_exited);
1282
1283                 xpc_do_exit(xpUnloading);
1284                 return -EBUSY;
1285         }
1286
1287         /* set the interface to point at XPC's functions */
1288         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1289                           xpc_initiate_allocate, xpc_initiate_send,
1290                           xpc_initiate_send_notify, xpc_initiate_received,
1291                           xpc_initiate_partid_to_nasids);
1292
1293         return 0;
1294 }
1295
1296 module_init(xpc_init);
1297
1298 void __exit
1299 xpc_exit(void)
1300 {
1301         xpc_do_exit(xpUnloading);
1302 }
1303
1304 module_exit(xpc_exit);
1305
1306 MODULE_AUTHOR("Silicon Graphics, Inc.");
1307 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1308 MODULE_LICENSE("GPL");
1309
1310 module_param(xpc_hb_interval, int, 0);
1311 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1312                  "heartbeat increments.");
1313
1314 module_param(xpc_hb_check_interval, int, 0);
1315 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1316                  "heartbeat checks.");
1317
1318 module_param(xpc_disengage_request_timelimit, int, 0);
1319 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1320                  "for disengage request to complete.");
1321
1322 module_param(xpc_kdebug_ignore, int, 0);
1323 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1324                  "other partitions when dropping into kdebug.");