GNU Linux-libre 4.4.284-gnu1
[releases.git] / 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) 2004-2009 Silicon Graphics, Inc.  All Rights Reserved.
7  */
8
9 /*
10  * Cross Partition Communication (XPC) support - standard version.
11  *
12  *      XPC provides a message passing capability that crosses partition
13  *      boundaries. This module is made up of two parts:
14  *
15  *          partition   This part detects the presence/absence of other
16  *                      partitions. It provides a heartbeat and monitors
17  *                      the heartbeats of other partitions.
18  *
19  *          channel     This part manages the channels and sends/receives
20  *                      messages across them to/from other partitions.
21  *
22  *      There are a couple of additional functions residing in XP, which
23  *      provide an interface to XPC for its users.
24  *
25  *
26  *      Caveats:
27  *
28  *        . Currently on sn2, we have no way to determine which nasid an IRQ
29  *          came from. Thus, xpc_send_IRQ_sn2() does a remote amo write
30  *          followed by an IPI. The amo indicates where data is to be pulled
31  *          from, so after the IPI arrives, the remote partition checks the amo
32  *          word. The IPI can actually arrive before the amo however, so other
33  *          code must periodically check for this case. Also, remote amo
34  *          operations do not reliably time out. Thus we do a remote PIO read
35  *          solely to know whether the remote partition is down and whether we
36  *          should stop sending IPIs to it. This remote PIO read operation is
37  *          set up in a special nofault region so SAL knows to ignore (and
38  *          cleanup) any errors due to the remote amo write, PIO read, and/or
39  *          PIO write operations.
40  *
41  *          If/when new hardware solves this IPI problem, we should abandon
42  *          the current approach.
43  *
44  */
45
46 #include <linux/module.h>
47 #include <linux/slab.h>
48 #include <linux/sysctl.h>
49 #include <linux/device.h>
50 #include <linux/delay.h>
51 #include <linux/reboot.h>
52 #include <linux/kdebug.h>
53 #include <linux/kthread.h>
54 #include "xpc.h"
55
56 #ifdef CONFIG_X86_64
57 #include <asm/traps.h>
58 #endif
59
60 /* define two XPC debug device structures to be used with dev_dbg() et al */
61
62 struct device_driver xpc_dbg_name = {
63         .name = "xpc"
64 };
65
66 struct device xpc_part_dbg_subname = {
67         .init_name = "",        /* set to "part" at xpc_init() time */
68         .driver = &xpc_dbg_name
69 };
70
71 struct device xpc_chan_dbg_subname = {
72         .init_name = "",        /* set to "chan" at xpc_init() time */
73         .driver = &xpc_dbg_name
74 };
75
76 struct device *xpc_part = &xpc_part_dbg_subname;
77 struct device *xpc_chan = &xpc_chan_dbg_subname;
78
79 static int xpc_kdebug_ignore;
80
81 /* systune related variables for /proc/sys directories */
82
83 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
84 static int xpc_hb_min_interval = 1;
85 static int xpc_hb_max_interval = 10;
86
87 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
88 static int xpc_hb_check_min_interval = 10;
89 static int xpc_hb_check_max_interval = 120;
90
91 int xpc_disengage_timelimit = XPC_DISENGAGE_DEFAULT_TIMELIMIT;
92 static int xpc_disengage_min_timelimit; /* = 0 */
93 static int xpc_disengage_max_timelimit = 120;
94
95 static struct ctl_table xpc_sys_xpc_hb_dir[] = {
96         {
97          .procname = "hb_interval",
98          .data = &xpc_hb_interval,
99          .maxlen = sizeof(int),
100          .mode = 0644,
101          .proc_handler = proc_dointvec_minmax,
102          .extra1 = &xpc_hb_min_interval,
103          .extra2 = &xpc_hb_max_interval},
104         {
105          .procname = "hb_check_interval",
106          .data = &xpc_hb_check_interval,
107          .maxlen = sizeof(int),
108          .mode = 0644,
109          .proc_handler = proc_dointvec_minmax,
110          .extra1 = &xpc_hb_check_min_interval,
111          .extra2 = &xpc_hb_check_max_interval},
112         {}
113 };
114 static struct ctl_table xpc_sys_xpc_dir[] = {
115         {
116          .procname = "hb",
117          .mode = 0555,
118          .child = xpc_sys_xpc_hb_dir},
119         {
120          .procname = "disengage_timelimit",
121          .data = &xpc_disengage_timelimit,
122          .maxlen = sizeof(int),
123          .mode = 0644,
124          .proc_handler = proc_dointvec_minmax,
125          .extra1 = &xpc_disengage_min_timelimit,
126          .extra2 = &xpc_disengage_max_timelimit},
127         {}
128 };
129 static struct ctl_table xpc_sys_dir[] = {
130         {
131          .procname = "xpc",
132          .mode = 0555,
133          .child = xpc_sys_xpc_dir},
134         {}
135 };
136 static struct ctl_table_header *xpc_sysctl;
137
138 /* non-zero if any remote partition disengage was timed out */
139 int xpc_disengage_timedout;
140
141 /* #of activate IRQs received and not yet processed */
142 int xpc_activate_IRQ_rcvd;
143 DEFINE_SPINLOCK(xpc_activate_IRQ_rcvd_lock);
144
145 /* IRQ handler notifies this wait queue on receipt of an IRQ */
146 DECLARE_WAIT_QUEUE_HEAD(xpc_activate_IRQ_wq);
147
148 static unsigned long xpc_hb_check_timeout;
149 static struct timer_list xpc_hb_timer;
150
151 /* notification that the xpc_hb_checker thread has exited */
152 static DECLARE_COMPLETION(xpc_hb_checker_exited);
153
154 /* notification that the xpc_discovery thread has exited */
155 static DECLARE_COMPLETION(xpc_discovery_exited);
156
157 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
158
159 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
160 static struct notifier_block xpc_reboot_notifier = {
161         .notifier_call = xpc_system_reboot,
162 };
163
164 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
165 static struct notifier_block xpc_die_notifier = {
166         .notifier_call = xpc_system_die,
167 };
168
169 struct xpc_arch_operations xpc_arch_ops;
170
171 /*
172  * Timer function to enforce the timelimit on the partition disengage.
173  */
174 static void
175 xpc_timeout_partition_disengage(unsigned long data)
176 {
177         struct xpc_partition *part = (struct xpc_partition *)data;
178
179         DBUG_ON(time_is_after_jiffies(part->disengage_timeout));
180
181         (void)xpc_partition_disengaged(part);
182
183         DBUG_ON(part->disengage_timeout != 0);
184         DBUG_ON(xpc_arch_ops.partition_engaged(XPC_PARTID(part)));
185 }
186
187 /*
188  * Timer to produce the heartbeat.  The timer structures function is
189  * already set when this is initially called.  A tunable is used to
190  * specify when the next timeout should occur.
191  */
192 static void
193 xpc_hb_beater(unsigned long dummy)
194 {
195         xpc_arch_ops.increment_heartbeat();
196
197         if (time_is_before_eq_jiffies(xpc_hb_check_timeout))
198                 wake_up_interruptible(&xpc_activate_IRQ_wq);
199
200         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
201         add_timer(&xpc_hb_timer);
202 }
203
204 static void
205 xpc_start_hb_beater(void)
206 {
207         xpc_arch_ops.heartbeat_init();
208         init_timer(&xpc_hb_timer);
209         xpc_hb_timer.function = xpc_hb_beater;
210         xpc_hb_beater(0);
211 }
212
213 static void
214 xpc_stop_hb_beater(void)
215 {
216         del_timer_sync(&xpc_hb_timer);
217         xpc_arch_ops.heartbeat_exit();
218 }
219
220 /*
221  * At periodic intervals, scan through all active partitions and ensure
222  * their heartbeat is still active.  If not, the partition is deactivated.
223  */
224 static void
225 xpc_check_remote_hb(void)
226 {
227         struct xpc_partition *part;
228         short partid;
229         enum xp_retval ret;
230
231         for (partid = 0; partid < xp_max_npartitions; partid++) {
232
233                 if (xpc_exiting)
234                         break;
235
236                 if (partid == xp_partition_id)
237                         continue;
238
239                 part = &xpc_partitions[partid];
240
241                 if (part->act_state == XPC_P_AS_INACTIVE ||
242                     part->act_state == XPC_P_AS_DEACTIVATING) {
243                         continue;
244                 }
245
246                 ret = xpc_arch_ops.get_remote_heartbeat(part);
247                 if (ret != xpSuccess)
248                         XPC_DEACTIVATE_PARTITION(part, ret);
249         }
250 }
251
252 /*
253  * This thread is responsible for nearly all of the partition
254  * activation/deactivation.
255  */
256 static int
257 xpc_hb_checker(void *ignore)
258 {
259         int force_IRQ = 0;
260
261         /* this thread was marked active by xpc_hb_init() */
262
263         set_cpus_allowed_ptr(current, cpumask_of(XPC_HB_CHECK_CPU));
264
265         /* set our heartbeating to other partitions into motion */
266         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
267         xpc_start_hb_beater();
268
269         while (!xpc_exiting) {
270
271                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
272                         "been received\n",
273                         (int)(xpc_hb_check_timeout - jiffies),
274                         xpc_activate_IRQ_rcvd);
275
276                 /* checking of remote heartbeats is skewed by IRQ handling */
277                 if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) {
278                         xpc_hb_check_timeout = jiffies +
279                             (xpc_hb_check_interval * HZ);
280
281                         dev_dbg(xpc_part, "checking remote heartbeats\n");
282                         xpc_check_remote_hb();
283
284                         /*
285                          * On sn2 we need to periodically recheck to ensure no
286                          * IRQ/amo pairs have been missed.
287                          */
288                         if (is_shub())
289                                 force_IRQ = 1;
290                 }
291
292                 /* check for outstanding IRQs */
293                 if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
294                         force_IRQ = 0;
295                         dev_dbg(xpc_part, "processing activate IRQs "
296                                 "received\n");
297                         xpc_arch_ops.process_activate_IRQ_rcvd();
298                 }
299
300                 /* wait for IRQ or timeout */
301                 (void)wait_event_interruptible(xpc_activate_IRQ_wq,
302                                                (time_is_before_eq_jiffies(
303                                                 xpc_hb_check_timeout) ||
304                                                 xpc_activate_IRQ_rcvd > 0 ||
305                                                 xpc_exiting));
306         }
307
308         xpc_stop_hb_beater();
309
310         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
311
312         /* mark this thread as having exited */
313         complete(&xpc_hb_checker_exited);
314         return 0;
315 }
316
317 /*
318  * This thread will attempt to discover other partitions to activate
319  * based on info provided by SAL. This new thread is short lived and
320  * will exit once discovery is complete.
321  */
322 static int
323 xpc_initiate_discovery(void *ignore)
324 {
325         xpc_discovery();
326
327         dev_dbg(xpc_part, "discovery thread is exiting\n");
328
329         /* mark this thread as having exited */
330         complete(&xpc_discovery_exited);
331         return 0;
332 }
333
334 /*
335  * The first kthread assigned to a newly activated partition is the one
336  * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
337  * that kthread until the partition is brought down, at which time that kthread
338  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
339  * that XPC has dismantled all communication infrastructure for the associated
340  * partition.) This kthread becomes the channel manager for that partition.
341  *
342  * Each active partition has a channel manager, who, besides connecting and
343  * disconnecting channels, will ensure that each of the partition's connected
344  * channels has the required number of assigned kthreads to get the work done.
345  */
346 static void
347 xpc_channel_mgr(struct xpc_partition *part)
348 {
349         while (part->act_state != XPC_P_AS_DEACTIVATING ||
350                atomic_read(&part->nchannels_active) > 0 ||
351                !xpc_partition_disengaged(part)) {
352
353                 xpc_process_sent_chctl_flags(part);
354
355                 /*
356                  * Wait until we've been requested to activate kthreads or
357                  * all of the channel's message queues have been torn down or
358                  * a signal is pending.
359                  *
360                  * The channel_mgr_requests is set to 1 after being awakened,
361                  * This is done to prevent the channel mgr from making one pass
362                  * through the loop for each request, since he will
363                  * be servicing all the requests in one pass. The reason it's
364                  * set to 1 instead of 0 is so that other kthreads will know
365                  * that the channel mgr is running and won't bother trying to
366                  * wake him up.
367                  */
368                 atomic_dec(&part->channel_mgr_requests);
369                 (void)wait_event_interruptible(part->channel_mgr_wq,
370                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
371                                  part->chctl.all_flags != 0 ||
372                                  (part->act_state == XPC_P_AS_DEACTIVATING &&
373                                  atomic_read(&part->nchannels_active) == 0 &&
374                                  xpc_partition_disengaged(part))));
375                 atomic_set(&part->channel_mgr_requests, 1);
376         }
377 }
378
379 /*
380  * Guarantee that the kzalloc'd memory is cacheline aligned.
381  */
382 void *
383 xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
384 {
385         /* see if kzalloc will give us cachline aligned memory by default */
386         *base = kzalloc(size, flags);
387         if (*base == NULL)
388                 return NULL;
389
390         if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
391                 return *base;
392
393         kfree(*base);
394
395         /* nope, we'll have to do it ourselves */
396         *base = kzalloc(size + L1_CACHE_BYTES, flags);
397         if (*base == NULL)
398                 return NULL;
399
400         return (void *)L1_CACHE_ALIGN((u64)*base);
401 }
402
403 /*
404  * Setup the channel structures necessary to support XPartition Communication
405  * between the specified remote partition and the local one.
406  */
407 static enum xp_retval
408 xpc_setup_ch_structures(struct xpc_partition *part)
409 {
410         enum xp_retval ret;
411         int ch_number;
412         struct xpc_channel *ch;
413         short partid = XPC_PARTID(part);
414
415         /*
416          * Allocate all of the channel structures as a contiguous chunk of
417          * memory.
418          */
419         DBUG_ON(part->channels != NULL);
420         part->channels = kzalloc(sizeof(struct xpc_channel) * XPC_MAX_NCHANNELS,
421                                  GFP_KERNEL);
422         if (part->channels == NULL) {
423                 dev_err(xpc_chan, "can't get memory for channels\n");
424                 return xpNoMemory;
425         }
426
427         /* allocate the remote open and close args */
428
429         part->remote_openclose_args =
430             xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
431                                           GFP_KERNEL, &part->
432                                           remote_openclose_args_base);
433         if (part->remote_openclose_args == NULL) {
434                 dev_err(xpc_chan, "can't get memory for remote connect args\n");
435                 ret = xpNoMemory;
436                 goto out_1;
437         }
438
439         part->chctl.all_flags = 0;
440         spin_lock_init(&part->chctl_lock);
441
442         atomic_set(&part->channel_mgr_requests, 1);
443         init_waitqueue_head(&part->channel_mgr_wq);
444
445         part->nchannels = XPC_MAX_NCHANNELS;
446
447         atomic_set(&part->nchannels_active, 0);
448         atomic_set(&part->nchannels_engaged, 0);
449
450         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
451                 ch = &part->channels[ch_number];
452
453                 ch->partid = partid;
454                 ch->number = ch_number;
455                 ch->flags = XPC_C_DISCONNECTED;
456
457                 atomic_set(&ch->kthreads_assigned, 0);
458                 atomic_set(&ch->kthreads_idle, 0);
459                 atomic_set(&ch->kthreads_active, 0);
460
461                 atomic_set(&ch->references, 0);
462                 atomic_set(&ch->n_to_notify, 0);
463
464                 spin_lock_init(&ch->lock);
465                 init_completion(&ch->wdisconnect_wait);
466
467                 atomic_set(&ch->n_on_msg_allocate_wq, 0);
468                 init_waitqueue_head(&ch->msg_allocate_wq);
469                 init_waitqueue_head(&ch->idle_wq);
470         }
471
472         ret = xpc_arch_ops.setup_ch_structures(part);
473         if (ret != xpSuccess)
474                 goto out_2;
475
476         /*
477          * With the setting of the partition setup_state to XPC_P_SS_SETUP,
478          * we're declaring that this partition is ready to go.
479          */
480         part->setup_state = XPC_P_SS_SETUP;
481
482         return xpSuccess;
483
484         /* setup of ch structures failed */
485 out_2:
486         kfree(part->remote_openclose_args_base);
487         part->remote_openclose_args = NULL;
488 out_1:
489         kfree(part->channels);
490         part->channels = NULL;
491         return ret;
492 }
493
494 /*
495  * Teardown the channel structures necessary to support XPartition Communication
496  * between the specified remote partition and the local one.
497  */
498 static void
499 xpc_teardown_ch_structures(struct xpc_partition *part)
500 {
501         DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
502         DBUG_ON(atomic_read(&part->nchannels_active) != 0);
503
504         /*
505          * Make this partition inaccessible to local processes by marking it
506          * as no longer setup. Then wait before proceeding with the teardown
507          * until all existing references cease.
508          */
509         DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
510         part->setup_state = XPC_P_SS_WTEARDOWN;
511
512         wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
513
514         /* now we can begin tearing down the infrastructure */
515
516         xpc_arch_ops.teardown_ch_structures(part);
517
518         kfree(part->remote_openclose_args_base);
519         part->remote_openclose_args = NULL;
520         kfree(part->channels);
521         part->channels = NULL;
522
523         part->setup_state = XPC_P_SS_TORNDOWN;
524 }
525
526 /*
527  * When XPC HB determines that a partition has come up, it will create a new
528  * kthread and that kthread will call this function to attempt to set up the
529  * basic infrastructure used for Cross Partition Communication with the newly
530  * upped partition.
531  *
532  * The kthread that was created by XPC HB and which setup the XPC
533  * infrastructure will remain assigned to the partition becoming the channel
534  * manager for that partition until the partition is deactivating, at which
535  * time the kthread will teardown the XPC infrastructure and then exit.
536  */
537 static int
538 xpc_activating(void *__partid)
539 {
540         short partid = (u64)__partid;
541         struct xpc_partition *part = &xpc_partitions[partid];
542         unsigned long irq_flags;
543
544         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
545
546         spin_lock_irqsave(&part->act_lock, irq_flags);
547
548         if (part->act_state == XPC_P_AS_DEACTIVATING) {
549                 part->act_state = XPC_P_AS_INACTIVE;
550                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
551                 part->remote_rp_pa = 0;
552                 return 0;
553         }
554
555         /* indicate the thread is activating */
556         DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
557         part->act_state = XPC_P_AS_ACTIVATING;
558
559         XPC_SET_REASON(part, 0, 0);
560         spin_unlock_irqrestore(&part->act_lock, irq_flags);
561
562         dev_dbg(xpc_part, "activating partition %d\n", partid);
563
564         xpc_arch_ops.allow_hb(partid);
565
566         if (xpc_setup_ch_structures(part) == xpSuccess) {
567                 (void)xpc_part_ref(part);       /* this will always succeed */
568
569                 if (xpc_arch_ops.make_first_contact(part) == xpSuccess) {
570                         xpc_mark_partition_active(part);
571                         xpc_channel_mgr(part);
572                         /* won't return until partition is deactivating */
573                 }
574
575                 xpc_part_deref(part);
576                 xpc_teardown_ch_structures(part);
577         }
578
579         xpc_arch_ops.disallow_hb(partid);
580         xpc_mark_partition_inactive(part);
581
582         if (part->reason == xpReactivating) {
583                 /* interrupting ourselves results in activating partition */
584                 xpc_arch_ops.request_partition_reactivation(part);
585         }
586
587         return 0;
588 }
589
590 void
591 xpc_activate_partition(struct xpc_partition *part)
592 {
593         short partid = XPC_PARTID(part);
594         unsigned long irq_flags;
595         struct task_struct *kthread;
596
597         spin_lock_irqsave(&part->act_lock, irq_flags);
598
599         DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
600
601         part->act_state = XPC_P_AS_ACTIVATION_REQ;
602         XPC_SET_REASON(part, xpCloneKThread, __LINE__);
603
604         spin_unlock_irqrestore(&part->act_lock, irq_flags);
605
606         kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
607                               partid);
608         if (IS_ERR(kthread)) {
609                 spin_lock_irqsave(&part->act_lock, irq_flags);
610                 part->act_state = XPC_P_AS_INACTIVE;
611                 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
612                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
613         }
614 }
615
616 void
617 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
618 {
619         int idle = atomic_read(&ch->kthreads_idle);
620         int assigned = atomic_read(&ch->kthreads_assigned);
621         int wakeup;
622
623         DBUG_ON(needed <= 0);
624
625         if (idle > 0) {
626                 wakeup = (needed > idle) ? idle : needed;
627                 needed -= wakeup;
628
629                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
630                         "channel=%d\n", wakeup, ch->partid, ch->number);
631
632                 /* only wakeup the requested number of kthreads */
633                 wake_up_nr(&ch->idle_wq, wakeup);
634         }
635
636         if (needed <= 0)
637                 return;
638
639         if (needed + assigned > ch->kthreads_assigned_limit) {
640                 needed = ch->kthreads_assigned_limit - assigned;
641                 if (needed <= 0)
642                         return;
643         }
644
645         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
646                 needed, ch->partid, ch->number);
647
648         xpc_create_kthreads(ch, needed, 0);
649 }
650
651 /*
652  * This function is where XPC's kthreads wait for messages to deliver.
653  */
654 static void
655 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
656 {
657         int (*n_of_deliverable_payloads) (struct xpc_channel *) =
658                 xpc_arch_ops.n_of_deliverable_payloads;
659
660         do {
661                 /* deliver messages to their intended recipients */
662
663                 while (n_of_deliverable_payloads(ch) > 0 &&
664                        !(ch->flags & XPC_C_DISCONNECTING)) {
665                         xpc_deliver_payload(ch);
666                 }
667
668                 if (atomic_inc_return(&ch->kthreads_idle) >
669                     ch->kthreads_idle_limit) {
670                         /* too many idle kthreads on this channel */
671                         atomic_dec(&ch->kthreads_idle);
672                         break;
673                 }
674
675                 dev_dbg(xpc_chan, "idle kthread calling "
676                         "wait_event_interruptible_exclusive()\n");
677
678                 (void)wait_event_interruptible_exclusive(ch->idle_wq,
679                                 (n_of_deliverable_payloads(ch) > 0 ||
680                                  (ch->flags & XPC_C_DISCONNECTING)));
681
682                 atomic_dec(&ch->kthreads_idle);
683
684         } while (!(ch->flags & XPC_C_DISCONNECTING));
685 }
686
687 static int
688 xpc_kthread_start(void *args)
689 {
690         short partid = XPC_UNPACK_ARG1(args);
691         u16 ch_number = XPC_UNPACK_ARG2(args);
692         struct xpc_partition *part = &xpc_partitions[partid];
693         struct xpc_channel *ch;
694         int n_needed;
695         unsigned long irq_flags;
696         int (*n_of_deliverable_payloads) (struct xpc_channel *) =
697                 xpc_arch_ops.n_of_deliverable_payloads;
698
699         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
700                 partid, ch_number);
701
702         ch = &part->channels[ch_number];
703
704         if (!(ch->flags & XPC_C_DISCONNECTING)) {
705
706                 /* let registerer know that connection has been established */
707
708                 spin_lock_irqsave(&ch->lock, irq_flags);
709                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
710                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
711                         spin_unlock_irqrestore(&ch->lock, irq_flags);
712
713                         xpc_connected_callout(ch);
714
715                         spin_lock_irqsave(&ch->lock, irq_flags);
716                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
717                         spin_unlock_irqrestore(&ch->lock, irq_flags);
718
719                         /*
720                          * It is possible that while the callout was being
721                          * made that the remote partition sent some messages.
722                          * If that is the case, we may need to activate
723                          * additional kthreads to help deliver them. We only
724                          * need one less than total #of messages to deliver.
725                          */
726                         n_needed = n_of_deliverable_payloads(ch) - 1;
727                         if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
728                                 xpc_activate_kthreads(ch, n_needed);
729
730                 } else {
731                         spin_unlock_irqrestore(&ch->lock, irq_flags);
732                 }
733
734                 xpc_kthread_waitmsgs(part, ch);
735         }
736
737         /* let registerer know that connection is disconnecting */
738
739         spin_lock_irqsave(&ch->lock, irq_flags);
740         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
741             !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
742                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
743                 spin_unlock_irqrestore(&ch->lock, irq_flags);
744
745                 xpc_disconnect_callout(ch, xpDisconnecting);
746
747                 spin_lock_irqsave(&ch->lock, irq_flags);
748                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
749         }
750         spin_unlock_irqrestore(&ch->lock, irq_flags);
751
752         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
753             atomic_dec_return(&part->nchannels_engaged) == 0) {
754                 xpc_arch_ops.indicate_partition_disengaged(part);
755         }
756
757         xpc_msgqueue_deref(ch);
758
759         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
760                 partid, ch_number);
761
762         xpc_part_deref(part);
763         return 0;
764 }
765
766 /*
767  * For each partition that XPC has established communications with, there is
768  * a minimum of one kernel thread assigned to perform any operation that
769  * may potentially sleep or block (basically the callouts to the asynchronous
770  * functions registered via xpc_connect()).
771  *
772  * Additional kthreads are created and destroyed by XPC as the workload
773  * demands.
774  *
775  * A kthread is assigned to one of the active channels that exists for a given
776  * partition.
777  */
778 void
779 xpc_create_kthreads(struct xpc_channel *ch, int needed,
780                     int ignore_disconnecting)
781 {
782         unsigned long irq_flags;
783         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
784         struct xpc_partition *part = &xpc_partitions[ch->partid];
785         struct task_struct *kthread;
786         void (*indicate_partition_disengaged) (struct xpc_partition *) =
787                 xpc_arch_ops.indicate_partition_disengaged;
788
789         while (needed-- > 0) {
790
791                 /*
792                  * The following is done on behalf of the newly created
793                  * kthread. That kthread is responsible for doing the
794                  * counterpart to the following before it exits.
795                  */
796                 if (ignore_disconnecting) {
797                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
798                                 /* kthreads assigned had gone to zero */
799                                 BUG_ON(!(ch->flags &
800                                          XPC_C_DISCONNECTINGCALLOUT_MADE));
801                                 break;
802                         }
803
804                 } else if (ch->flags & XPC_C_DISCONNECTING) {
805                         break;
806
807                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
808                            atomic_inc_return(&part->nchannels_engaged) == 1) {
809                         xpc_arch_ops.indicate_partition_engaged(part);
810                 }
811                 (void)xpc_part_ref(part);
812                 xpc_msgqueue_ref(ch);
813
814                 kthread = kthread_run(xpc_kthread_start, (void *)args,
815                                       "xpc%02dc%d", ch->partid, ch->number);
816                 if (IS_ERR(kthread)) {
817                         /* the fork failed */
818
819                         /*
820                          * NOTE: if (ignore_disconnecting &&
821                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
822                          * then we'll deadlock if all other kthreads assigned
823                          * to this channel are blocked in the channel's
824                          * registerer, because the only thing that will unblock
825                          * them is the xpDisconnecting callout that this
826                          * failed kthread_run() would have made.
827                          */
828
829                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
830                             atomic_dec_return(&part->nchannels_engaged) == 0) {
831                                 indicate_partition_disengaged(part);
832                         }
833                         xpc_msgqueue_deref(ch);
834                         xpc_part_deref(part);
835
836                         if (atomic_read(&ch->kthreads_assigned) <
837                             ch->kthreads_idle_limit) {
838                                 /*
839                                  * Flag this as an error only if we have an
840                                  * insufficient #of kthreads for the channel
841                                  * to function.
842                                  */
843                                 spin_lock_irqsave(&ch->lock, irq_flags);
844                                 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
845                                                        &irq_flags);
846                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
847                         }
848                         break;
849                 }
850         }
851 }
852
853 void
854 xpc_disconnect_wait(int ch_number)
855 {
856         unsigned long irq_flags;
857         short partid;
858         struct xpc_partition *part;
859         struct xpc_channel *ch;
860         int wakeup_channel_mgr;
861
862         /* now wait for all callouts to the caller's function to cease */
863         for (partid = 0; partid < xp_max_npartitions; partid++) {
864                 part = &xpc_partitions[partid];
865
866                 if (!xpc_part_ref(part))
867                         continue;
868
869                 ch = &part->channels[ch_number];
870
871                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
872                         xpc_part_deref(part);
873                         continue;
874                 }
875
876                 wait_for_completion(&ch->wdisconnect_wait);
877
878                 spin_lock_irqsave(&ch->lock, irq_flags);
879                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
880                 wakeup_channel_mgr = 0;
881
882                 if (ch->delayed_chctl_flags) {
883                         if (part->act_state != XPC_P_AS_DEACTIVATING) {
884                                 spin_lock(&part->chctl_lock);
885                                 part->chctl.flags[ch->number] |=
886                                     ch->delayed_chctl_flags;
887                                 spin_unlock(&part->chctl_lock);
888                                 wakeup_channel_mgr = 1;
889                         }
890                         ch->delayed_chctl_flags = 0;
891                 }
892
893                 ch->flags &= ~XPC_C_WDISCONNECT;
894                 spin_unlock_irqrestore(&ch->lock, irq_flags);
895
896                 if (wakeup_channel_mgr)
897                         xpc_wakeup_channel_mgr(part);
898
899                 xpc_part_deref(part);
900         }
901 }
902
903 static int
904 xpc_setup_partitions(void)
905 {
906         short partid;
907         struct xpc_partition *part;
908
909         xpc_partitions = kzalloc(sizeof(struct xpc_partition) *
910                                  xp_max_npartitions, GFP_KERNEL);
911         if (xpc_partitions == NULL) {
912                 dev_err(xpc_part, "can't get memory for partition structure\n");
913                 return -ENOMEM;
914         }
915
916         /*
917          * The first few fields of each entry of xpc_partitions[] need to
918          * be initialized now so that calls to xpc_connect() and
919          * xpc_disconnect() can be made prior to the activation of any remote
920          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
921          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
922          * PARTITION HAS BEEN ACTIVATED.
923          */
924         for (partid = 0; partid < xp_max_npartitions; partid++) {
925                 part = &xpc_partitions[partid];
926
927                 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
928
929                 part->activate_IRQ_rcvd = 0;
930                 spin_lock_init(&part->act_lock);
931                 part->act_state = XPC_P_AS_INACTIVE;
932                 XPC_SET_REASON(part, 0, 0);
933
934                 init_timer(&part->disengage_timer);
935                 part->disengage_timer.function =
936                     xpc_timeout_partition_disengage;
937                 part->disengage_timer.data = (unsigned long)part;
938
939                 part->setup_state = XPC_P_SS_UNSET;
940                 init_waitqueue_head(&part->teardown_wq);
941                 atomic_set(&part->references, 0);
942         }
943
944         return xpc_arch_ops.setup_partitions();
945 }
946
947 static void
948 xpc_teardown_partitions(void)
949 {
950         xpc_arch_ops.teardown_partitions();
951         kfree(xpc_partitions);
952 }
953
954 static void
955 xpc_do_exit(enum xp_retval reason)
956 {
957         short partid;
958         int active_part_count, printed_waiting_msg = 0;
959         struct xpc_partition *part;
960         unsigned long printmsg_time, disengage_timeout = 0;
961
962         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
963         DBUG_ON(xpc_exiting == 1);
964
965         /*
966          * Let the heartbeat checker thread and the discovery thread
967          * (if one is running) know that they should exit. Also wake up
968          * the heartbeat checker thread in case it's sleeping.
969          */
970         xpc_exiting = 1;
971         wake_up_interruptible(&xpc_activate_IRQ_wq);
972
973         /* wait for the discovery thread to exit */
974         wait_for_completion(&xpc_discovery_exited);
975
976         /* wait for the heartbeat checker thread to exit */
977         wait_for_completion(&xpc_hb_checker_exited);
978
979         /* sleep for a 1/3 of a second or so */
980         (void)msleep_interruptible(300);
981
982         /* wait for all partitions to become inactive */
983
984         printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
985         xpc_disengage_timedout = 0;
986
987         do {
988                 active_part_count = 0;
989
990                 for (partid = 0; partid < xp_max_npartitions; partid++) {
991                         part = &xpc_partitions[partid];
992
993                         if (xpc_partition_disengaged(part) &&
994                             part->act_state == XPC_P_AS_INACTIVE) {
995                                 continue;
996                         }
997
998                         active_part_count++;
999
1000                         XPC_DEACTIVATE_PARTITION(part, reason);
1001
1002                         if (part->disengage_timeout > disengage_timeout)
1003                                 disengage_timeout = part->disengage_timeout;
1004                 }
1005
1006                 if (xpc_arch_ops.any_partition_engaged()) {
1007                         if (time_is_before_jiffies(printmsg_time)) {
1008                                 dev_info(xpc_part, "waiting for remote "
1009                                          "partitions to deactivate, timeout in "
1010                                          "%ld seconds\n", (disengage_timeout -
1011                                          jiffies) / HZ);
1012                                 printmsg_time = jiffies +
1013                                     (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1014                                 printed_waiting_msg = 1;
1015                         }
1016
1017                 } else if (active_part_count > 0) {
1018                         if (printed_waiting_msg) {
1019                                 dev_info(xpc_part, "waiting for local partition"
1020                                          " to deactivate\n");
1021                                 printed_waiting_msg = 0;
1022                         }
1023
1024                 } else {
1025                         if (!xpc_disengage_timedout) {
1026                                 dev_info(xpc_part, "all partitions have "
1027                                          "deactivated\n");
1028                         }
1029                         break;
1030                 }
1031
1032                 /* sleep for a 1/3 of a second or so */
1033                 (void)msleep_interruptible(300);
1034
1035         } while (1);
1036
1037         DBUG_ON(xpc_arch_ops.any_partition_engaged());
1038
1039         xpc_teardown_rsvd_page();
1040
1041         if (reason == xpUnloading) {
1042                 (void)unregister_die_notifier(&xpc_die_notifier);
1043                 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1044         }
1045
1046         /* clear the interface to XPC's functions */
1047         xpc_clear_interface();
1048
1049         if (xpc_sysctl)
1050                 unregister_sysctl_table(xpc_sysctl);
1051
1052         xpc_teardown_partitions();
1053
1054         if (is_shub())
1055                 xpc_exit_sn2();
1056         else if (is_uv())
1057                 xpc_exit_uv();
1058 }
1059
1060 /*
1061  * This function is called when the system is being rebooted.
1062  */
1063 static int
1064 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1065 {
1066         enum xp_retval reason;
1067
1068         switch (event) {
1069         case SYS_RESTART:
1070                 reason = xpSystemReboot;
1071                 break;
1072         case SYS_HALT:
1073                 reason = xpSystemHalt;
1074                 break;
1075         case SYS_POWER_OFF:
1076                 reason = xpSystemPoweroff;
1077                 break;
1078         default:
1079                 reason = xpSystemGoingDown;
1080         }
1081
1082         xpc_do_exit(reason);
1083         return NOTIFY_DONE;
1084 }
1085
1086 /* Used to only allow one cpu to complete disconnect */
1087 static unsigned int xpc_die_disconnecting;
1088
1089 /*
1090  * Notify other partitions to deactivate from us by first disengaging from all
1091  * references to our memory.
1092  */
1093 static void
1094 xpc_die_deactivate(void)
1095 {
1096         struct xpc_partition *part;
1097         short partid;
1098         int any_engaged;
1099         long keep_waiting;
1100         long wait_to_print;
1101
1102         if (cmpxchg(&xpc_die_disconnecting, 0, 1))
1103                 return;
1104
1105         /* keep xpc_hb_checker thread from doing anything (just in case) */
1106         xpc_exiting = 1;
1107
1108         xpc_arch_ops.disallow_all_hbs();   /*indicate we're deactivated */
1109
1110         for (partid = 0; partid < xp_max_npartitions; partid++) {
1111                 part = &xpc_partitions[partid];
1112
1113                 if (xpc_arch_ops.partition_engaged(partid) ||
1114                     part->act_state != XPC_P_AS_INACTIVE) {
1115                         xpc_arch_ops.request_partition_deactivation(part);
1116                         xpc_arch_ops.indicate_partition_disengaged(part);
1117                 }
1118         }
1119
1120         /*
1121          * Though we requested that all other partitions deactivate from us,
1122          * we only wait until they've all disengaged or we've reached the
1123          * defined timelimit.
1124          *
1125          * Given that one iteration through the following while-loop takes
1126          * approximately 200 microseconds, calculate the #of loops to take
1127          * before bailing and the #of loops before printing a waiting message.
1128          */
1129         keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1130         wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1131
1132         while (1) {
1133                 any_engaged = xpc_arch_ops.any_partition_engaged();
1134                 if (!any_engaged) {
1135                         dev_info(xpc_part, "all partitions have deactivated\n");
1136                         break;
1137                 }
1138
1139                 if (!keep_waiting--) {
1140                         for (partid = 0; partid < xp_max_npartitions;
1141                              partid++) {
1142                                 if (xpc_arch_ops.partition_engaged(partid)) {
1143                                         dev_info(xpc_part, "deactivate from "
1144                                                  "remote partition %d timed "
1145                                                  "out\n", partid);
1146                                 }
1147                         }
1148                         break;
1149                 }
1150
1151                 if (!wait_to_print--) {
1152                         dev_info(xpc_part, "waiting for remote partitions to "
1153                                  "deactivate, timeout in %ld seconds\n",
1154                                  keep_waiting / (1000 * 5));
1155                         wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1156                             1000 * 5;
1157                 }
1158
1159                 udelay(200);
1160         }
1161 }
1162
1163 /*
1164  * This function is called when the system is being restarted or halted due
1165  * to some sort of system failure. If this is the case we need to notify the
1166  * other partitions to disengage from all references to our memory.
1167  * This function can also be called when our heartbeater could be offlined
1168  * for a time. In this case we need to notify other partitions to not worry
1169  * about the lack of a heartbeat.
1170  */
1171 static int
1172 xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args)
1173 {
1174 #ifdef CONFIG_IA64              /* !!! temporary kludge */
1175         switch (event) {
1176         case DIE_MACHINE_RESTART:
1177         case DIE_MACHINE_HALT:
1178                 xpc_die_deactivate();
1179                 break;
1180
1181         case DIE_KDEBUG_ENTER:
1182                 /* Should lack of heartbeat be ignored by other partitions? */
1183                 if (!xpc_kdebug_ignore)
1184                         break;
1185
1186                 /* fall through */
1187         case DIE_MCA_MONARCH_ENTER:
1188         case DIE_INIT_MONARCH_ENTER:
1189                 xpc_arch_ops.offline_heartbeat();
1190                 break;
1191
1192         case DIE_KDEBUG_LEAVE:
1193                 /* Is lack of heartbeat being ignored by other partitions? */
1194                 if (!xpc_kdebug_ignore)
1195                         break;
1196
1197                 /* fall through */
1198         case DIE_MCA_MONARCH_LEAVE:
1199         case DIE_INIT_MONARCH_LEAVE:
1200                 xpc_arch_ops.online_heartbeat();
1201                 break;
1202         }
1203 #else
1204         struct die_args *die_args = _die_args;
1205
1206         switch (event) {
1207         case DIE_TRAP:
1208                 if (die_args->trapnr == X86_TRAP_DF)
1209                         xpc_die_deactivate();
1210
1211                 if (((die_args->trapnr == X86_TRAP_MF) ||
1212                      (die_args->trapnr == X86_TRAP_XF)) &&
1213                     !user_mode(die_args->regs))
1214                         xpc_die_deactivate();
1215
1216                 break;
1217         case DIE_INT3:
1218         case DIE_DEBUG:
1219                 break;
1220         case DIE_OOPS:
1221         case DIE_GPF:
1222         default:
1223                 xpc_die_deactivate();
1224         }
1225 #endif
1226
1227         return NOTIFY_DONE;
1228 }
1229
1230 int __init
1231 xpc_init(void)
1232 {
1233         int ret;
1234         struct task_struct *kthread;
1235
1236         dev_set_name(xpc_part, "part");
1237         dev_set_name(xpc_chan, "chan");
1238
1239         if (is_shub()) {
1240                 /*
1241                  * The ia64-sn2 architecture supports at most 64 partitions.
1242                  * And the inability to unregister remote amos restricts us
1243                  * further to only support exactly 64 partitions on this
1244                  * architecture, no less.
1245                  */
1246                 if (xp_max_npartitions != 64) {
1247                         dev_err(xpc_part, "max #of partitions not set to 64\n");
1248                         ret = -EINVAL;
1249                 } else {
1250                         ret = xpc_init_sn2();
1251                 }
1252
1253         } else if (is_uv()) {
1254                 ret = xpc_init_uv();
1255
1256         } else {
1257                 ret = -ENODEV;
1258         }
1259
1260         if (ret != 0)
1261                 return ret;
1262
1263         ret = xpc_setup_partitions();
1264         if (ret != 0) {
1265                 dev_err(xpc_part, "can't get memory for partition structure\n");
1266                 goto out_1;
1267         }
1268
1269         xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1270
1271         /*
1272          * Fill the partition reserved page with the information needed by
1273          * other partitions to discover we are alive and establish initial
1274          * communications.
1275          */
1276         ret = xpc_setup_rsvd_page();
1277         if (ret != 0) {
1278                 dev_err(xpc_part, "can't setup our reserved page\n");
1279                 goto out_2;
1280         }
1281
1282         /* add ourselves to the reboot_notifier_list */
1283         ret = register_reboot_notifier(&xpc_reboot_notifier);
1284         if (ret != 0)
1285                 dev_warn(xpc_part, "can't register reboot notifier\n");
1286
1287         /* add ourselves to the die_notifier list */
1288         ret = register_die_notifier(&xpc_die_notifier);
1289         if (ret != 0)
1290                 dev_warn(xpc_part, "can't register die notifier\n");
1291
1292         /*
1293          * The real work-horse behind xpc.  This processes incoming
1294          * interrupts and monitors remote heartbeats.
1295          */
1296         kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1297         if (IS_ERR(kthread)) {
1298                 dev_err(xpc_part, "failed while forking hb check thread\n");
1299                 ret = -EBUSY;
1300                 goto out_3;
1301         }
1302
1303         /*
1304          * Startup a thread that will attempt to discover other partitions to
1305          * activate based on info provided by SAL. This new thread is short
1306          * lived and will exit once discovery is complete.
1307          */
1308         kthread = kthread_run(xpc_initiate_discovery, NULL,
1309                               XPC_DISCOVERY_THREAD_NAME);
1310         if (IS_ERR(kthread)) {
1311                 dev_err(xpc_part, "failed while forking discovery thread\n");
1312
1313                 /* mark this new thread as a non-starter */
1314                 complete(&xpc_discovery_exited);
1315
1316                 xpc_do_exit(xpUnloading);
1317                 return -EBUSY;
1318         }
1319
1320         /* set the interface to point at XPC's functions */
1321         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1322                           xpc_initiate_send, xpc_initiate_send_notify,
1323                           xpc_initiate_received, xpc_initiate_partid_to_nasids);
1324
1325         return 0;
1326
1327         /* initialization was not successful */
1328 out_3:
1329         xpc_teardown_rsvd_page();
1330
1331         (void)unregister_die_notifier(&xpc_die_notifier);
1332         (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1333 out_2:
1334         if (xpc_sysctl)
1335                 unregister_sysctl_table(xpc_sysctl);
1336
1337         xpc_teardown_partitions();
1338 out_1:
1339         if (is_shub())
1340                 xpc_exit_sn2();
1341         else if (is_uv())
1342                 xpc_exit_uv();
1343         return ret;
1344 }
1345
1346 module_init(xpc_init);
1347
1348 void __exit
1349 xpc_exit(void)
1350 {
1351         xpc_do_exit(xpUnloading);
1352 }
1353
1354 module_exit(xpc_exit);
1355
1356 MODULE_AUTHOR("Silicon Graphics, Inc.");
1357 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1358 MODULE_LICENSE("GPL");
1359
1360 module_param(xpc_hb_interval, int, 0);
1361 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1362                  "heartbeat increments.");
1363
1364 module_param(xpc_hb_check_interval, int, 0);
1365 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1366                  "heartbeat checks.");
1367
1368 module_param(xpc_disengage_timelimit, int, 0);
1369 MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1370                  "for disengage to complete.");
1371
1372 module_param(xpc_kdebug_ignore, int, 0);
1373 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1374                  "other partitions when dropping into kdebug.");