sgi-xpc: prevent false heartbeat failures
[linux-2.6.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/sysctl.h>
48 #include <linux/device.h>
49 #include <linux/delay.h>
50 #include <linux/reboot.h>
51 #include <linux/kdebug.h>
52 #include <linux/kthread.h>
53 #include "xpc.h"
54
55 /* define two XPC debug device structures to be used with dev_dbg() et al */
56
57 struct device_driver xpc_dbg_name = {
58         .name = "xpc"
59 };
60
61 struct device xpc_part_dbg_subname = {
62         .init_name = "",        /* set to "part" at xpc_init() time */
63         .driver = &xpc_dbg_name
64 };
65
66 struct device xpc_chan_dbg_subname = {
67         .init_name = "",        /* set to "chan" at xpc_init() time */
68         .driver = &xpc_dbg_name
69 };
70
71 struct device *xpc_part = &xpc_part_dbg_subname;
72 struct device *xpc_chan = &xpc_chan_dbg_subname;
73
74 static int xpc_kdebug_ignore;
75
76 /* systune related variables for /proc/sys directories */
77
78 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
79 static int xpc_hb_min_interval = 1;
80 static int xpc_hb_max_interval = 10;
81
82 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
83 static int xpc_hb_check_min_interval = 10;
84 static int xpc_hb_check_max_interval = 120;
85
86 int xpc_disengage_timelimit = XPC_DISENGAGE_DEFAULT_TIMELIMIT;
87 static int xpc_disengage_min_timelimit; /* = 0 */
88 static int xpc_disengage_max_timelimit = 120;
89
90 static ctl_table xpc_sys_xpc_hb_dir[] = {
91         {
92          .ctl_name = CTL_UNNUMBERED,
93          .procname = "hb_interval",
94          .data = &xpc_hb_interval,
95          .maxlen = sizeof(int),
96          .mode = 0644,
97          .proc_handler = &proc_dointvec_minmax,
98          .strategy = &sysctl_intvec,
99          .extra1 = &xpc_hb_min_interval,
100          .extra2 = &xpc_hb_max_interval},
101         {
102          .ctl_name = CTL_UNNUMBERED,
103          .procname = "hb_check_interval",
104          .data = &xpc_hb_check_interval,
105          .maxlen = sizeof(int),
106          .mode = 0644,
107          .proc_handler = &proc_dointvec_minmax,
108          .strategy = &sysctl_intvec,
109          .extra1 = &xpc_hb_check_min_interval,
110          .extra2 = &xpc_hb_check_max_interval},
111         {}
112 };
113 static ctl_table xpc_sys_xpc_dir[] = {
114         {
115          .ctl_name = CTL_UNNUMBERED,
116          .procname = "hb",
117          .mode = 0555,
118          .child = xpc_sys_xpc_hb_dir},
119         {
120          .ctl_name = CTL_UNNUMBERED,
121          .procname = "disengage_timelimit",
122          .data = &xpc_disengage_timelimit,
123          .maxlen = sizeof(int),
124          .mode = 0644,
125          .proc_handler = &proc_dointvec_minmax,
126          .strategy = &sysctl_intvec,
127          .extra1 = &xpc_disengage_min_timelimit,
128          .extra2 = &xpc_disengage_max_timelimit},
129         {}
130 };
131 static ctl_table xpc_sys_dir[] = {
132         {
133          .ctl_name = CTL_UNNUMBERED,
134          .procname = "xpc",
135          .mode = 0555,
136          .child = xpc_sys_xpc_dir},
137         {}
138 };
139 static struct ctl_table_header *xpc_sysctl;
140
141 /* non-zero if any remote partition disengage was timed out */
142 int xpc_disengage_timedout;
143
144 /* #of activate IRQs received and not yet processed */
145 int xpc_activate_IRQ_rcvd;
146 DEFINE_SPINLOCK(xpc_activate_IRQ_rcvd_lock);
147
148 /* IRQ handler notifies this wait queue on receipt of an IRQ */
149 DECLARE_WAIT_QUEUE_HEAD(xpc_activate_IRQ_wq);
150
151 static unsigned long xpc_hb_check_timeout;
152 static struct timer_list xpc_hb_timer;
153
154 /* notification that the xpc_hb_checker thread has exited */
155 static DECLARE_COMPLETION(xpc_hb_checker_exited);
156
157 /* notification that the xpc_discovery thread has exited */
158 static DECLARE_COMPLETION(xpc_discovery_exited);
159
160 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
161
162 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
163 static struct notifier_block xpc_reboot_notifier = {
164         .notifier_call = xpc_system_reboot,
165 };
166
167 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
168 static struct notifier_block xpc_die_notifier = {
169         .notifier_call = xpc_system_die,
170 };
171
172 int (*xpc_setup_partitions_sn) (void);
173 void (*xpc_teardown_partitions_sn) (void);
174 enum xp_retval (*xpc_get_partition_rsvd_page_pa) (void *buf, u64 *cookie,
175                                                   unsigned long *rp_pa,
176                                                   size_t *len);
177 int (*xpc_setup_rsvd_page_sn) (struct xpc_rsvd_page *rp);
178
179 void (*xpc_allow_hb) (short partid);
180 void (*xpc_disallow_hb) (short partid);
181 void (*xpc_disallow_all_hbs) (void);
182 void (*xpc_heartbeat_init) (void);
183 void (*xpc_heartbeat_exit) (void);
184 void (*xpc_increment_heartbeat) (void);
185 void (*xpc_offline_heartbeat) (void);
186 void (*xpc_online_heartbeat) (void);
187 enum xp_retval (*xpc_get_remote_heartbeat) (struct xpc_partition *part);
188
189 enum xp_retval (*xpc_make_first_contact) (struct xpc_partition *part);
190 void (*xpc_notify_senders_of_disconnect) (struct xpc_channel *ch);
191 u64 (*xpc_get_chctl_all_flags) (struct xpc_partition *part);
192 enum xp_retval (*xpc_setup_msg_structures) (struct xpc_channel *ch);
193 void (*xpc_teardown_msg_structures) (struct xpc_channel *ch);
194 void (*xpc_process_msg_chctl_flags) (struct xpc_partition *part, int ch_number);
195 int (*xpc_n_of_deliverable_payloads) (struct xpc_channel *ch);
196 void *(*xpc_get_deliverable_payload) (struct xpc_channel *ch);
197
198 void (*xpc_request_partition_activation) (struct xpc_rsvd_page *remote_rp,
199                                           unsigned long remote_rp_pa,
200                                           int nasid);
201 void (*xpc_request_partition_reactivation) (struct xpc_partition *part);
202 void (*xpc_request_partition_deactivation) (struct xpc_partition *part);
203 void (*xpc_cancel_partition_deactivation_request) (struct xpc_partition *part);
204
205 void (*xpc_process_activate_IRQ_rcvd) (void);
206 enum xp_retval (*xpc_setup_ch_structures_sn) (struct xpc_partition *part);
207 void (*xpc_teardown_ch_structures_sn) (struct xpc_partition *part);
208
209 void (*xpc_indicate_partition_engaged) (struct xpc_partition *part);
210 int (*xpc_partition_engaged) (short partid);
211 int (*xpc_any_partition_engaged) (void);
212 void (*xpc_indicate_partition_disengaged) (struct xpc_partition *part);
213 void (*xpc_assume_partition_disengaged) (short partid);
214
215 void (*xpc_send_chctl_closerequest) (struct xpc_channel *ch,
216                                      unsigned long *irq_flags);
217 void (*xpc_send_chctl_closereply) (struct xpc_channel *ch,
218                                    unsigned long *irq_flags);
219 void (*xpc_send_chctl_openrequest) (struct xpc_channel *ch,
220                                     unsigned long *irq_flags);
221 void (*xpc_send_chctl_openreply) (struct xpc_channel *ch,
222                                   unsigned long *irq_flags);
223
224 enum xp_retval (*xpc_save_remote_msgqueue_pa) (struct xpc_channel *ch,
225                                                unsigned long msgqueue_pa);
226
227 enum xp_retval (*xpc_send_payload) (struct xpc_channel *ch, u32 flags,
228                                     void *payload, u16 payload_size,
229                                     u8 notify_type, xpc_notify_func func,
230                                     void *key);
231 void (*xpc_received_payload) (struct xpc_channel *ch, void *payload);
232
233 /*
234  * Timer function to enforce the timelimit on the partition disengage.
235  */
236 static void
237 xpc_timeout_partition_disengage(unsigned long data)
238 {
239         struct xpc_partition *part = (struct xpc_partition *)data;
240
241         DBUG_ON(time_is_after_jiffies(part->disengage_timeout));
242
243         (void)xpc_partition_disengaged(part);
244
245         DBUG_ON(part->disengage_timeout != 0);
246         DBUG_ON(xpc_partition_engaged(XPC_PARTID(part)));
247 }
248
249 /*
250  * Timer to produce the heartbeat.  The timer structures function is
251  * already set when this is initially called.  A tunable is used to
252  * specify when the next timeout should occur.
253  */
254 static void
255 xpc_hb_beater(unsigned long dummy)
256 {
257         xpc_increment_heartbeat();
258
259         if (time_is_before_eq_jiffies(xpc_hb_check_timeout))
260                 wake_up_interruptible(&xpc_activate_IRQ_wq);
261
262         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
263         add_timer(&xpc_hb_timer);
264 }
265
266 static void
267 xpc_start_hb_beater(void)
268 {
269         xpc_heartbeat_init();
270         init_timer(&xpc_hb_timer);
271         xpc_hb_timer.function = xpc_hb_beater;
272         xpc_hb_beater(0);
273 }
274
275 static void
276 xpc_stop_hb_beater(void)
277 {
278         del_timer_sync(&xpc_hb_timer);
279         xpc_heartbeat_exit();
280 }
281
282 /*
283  * At periodic intervals, scan through all active partitions and ensure
284  * their heartbeat is still active.  If not, the partition is deactivated.
285  */
286 static void
287 xpc_check_remote_hb(void)
288 {
289         struct xpc_partition *part;
290         short partid;
291         enum xp_retval ret;
292
293         for (partid = 0; partid < xp_max_npartitions; partid++) {
294
295                 if (xpc_exiting)
296                         break;
297
298                 if (partid == xp_partition_id)
299                         continue;
300
301                 part = &xpc_partitions[partid];
302
303                 if (part->act_state == XPC_P_AS_INACTIVE ||
304                     part->act_state == XPC_P_AS_DEACTIVATING) {
305                         continue;
306                 }
307
308                 ret = xpc_get_remote_heartbeat(part);
309                 if (ret != xpSuccess)
310                         XPC_DEACTIVATE_PARTITION(part, ret);
311         }
312 }
313
314 /*
315  * This thread is responsible for nearly all of the partition
316  * activation/deactivation.
317  */
318 static int
319 xpc_hb_checker(void *ignore)
320 {
321         int force_IRQ = 0;
322
323         /* this thread was marked active by xpc_hb_init() */
324
325         set_cpus_allowed_ptr(current, cpumask_of(XPC_HB_CHECK_CPU));
326
327         /* set our heartbeating to other partitions into motion */
328         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
329         xpc_start_hb_beater();
330
331         while (!xpc_exiting) {
332
333                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
334                         "been received\n",
335                         (int)(xpc_hb_check_timeout - jiffies),
336                         xpc_activate_IRQ_rcvd);
337
338                 /* checking of remote heartbeats is skewed by IRQ handling */
339                 if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) {
340                         xpc_hb_check_timeout = jiffies +
341                             (xpc_hb_check_interval * HZ);
342
343                         dev_dbg(xpc_part, "checking remote heartbeats\n");
344                         xpc_check_remote_hb();
345
346                         /*
347                          * On sn2 we need to periodically recheck to ensure no
348                          * IRQ/amo pairs have been missed.
349                          */
350                         if (is_shub())
351                                 force_IRQ = 1;
352                 }
353
354                 /* check for outstanding IRQs */
355                 if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
356                         force_IRQ = 0;
357                         dev_dbg(xpc_part, "processing activate IRQs "
358                                 "received\n");
359                         xpc_process_activate_IRQ_rcvd();
360                 }
361
362                 /* wait for IRQ or timeout */
363                 (void)wait_event_interruptible(xpc_activate_IRQ_wq,
364                                                (time_is_before_eq_jiffies(
365                                                 xpc_hb_check_timeout) ||
366                                                 xpc_activate_IRQ_rcvd > 0 ||
367                                                 xpc_exiting));
368         }
369
370         xpc_stop_hb_beater();
371
372         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
373
374         /* mark this thread as having exited */
375         complete(&xpc_hb_checker_exited);
376         return 0;
377 }
378
379 /*
380  * This thread will attempt to discover other partitions to activate
381  * based on info provided by SAL. This new thread is short lived and
382  * will exit once discovery is complete.
383  */
384 static int
385 xpc_initiate_discovery(void *ignore)
386 {
387         xpc_discovery();
388
389         dev_dbg(xpc_part, "discovery thread is exiting\n");
390
391         /* mark this thread as having exited */
392         complete(&xpc_discovery_exited);
393         return 0;
394 }
395
396 /*
397  * The first kthread assigned to a newly activated partition is the one
398  * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
399  * that kthread until the partition is brought down, at which time that kthread
400  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
401  * that XPC has dismantled all communication infrastructure for the associated
402  * partition.) This kthread becomes the channel manager for that partition.
403  *
404  * Each active partition has a channel manager, who, besides connecting and
405  * disconnecting channels, will ensure that each of the partition's connected
406  * channels has the required number of assigned kthreads to get the work done.
407  */
408 static void
409 xpc_channel_mgr(struct xpc_partition *part)
410 {
411         while (part->act_state != XPC_P_AS_DEACTIVATING ||
412                atomic_read(&part->nchannels_active) > 0 ||
413                !xpc_partition_disengaged(part)) {
414
415                 xpc_process_sent_chctl_flags(part);
416
417                 /*
418                  * Wait until we've been requested to activate kthreads or
419                  * all of the channel's message queues have been torn down or
420                  * a signal is pending.
421                  *
422                  * The channel_mgr_requests is set to 1 after being awakened,
423                  * This is done to prevent the channel mgr from making one pass
424                  * through the loop for each request, since he will
425                  * be servicing all the requests in one pass. The reason it's
426                  * set to 1 instead of 0 is so that other kthreads will know
427                  * that the channel mgr is running and won't bother trying to
428                  * wake him up.
429                  */
430                 atomic_dec(&part->channel_mgr_requests);
431                 (void)wait_event_interruptible(part->channel_mgr_wq,
432                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
433                                  part->chctl.all_flags != 0 ||
434                                  (part->act_state == XPC_P_AS_DEACTIVATING &&
435                                  atomic_read(&part->nchannels_active) == 0 &&
436                                  xpc_partition_disengaged(part))));
437                 atomic_set(&part->channel_mgr_requests, 1);
438         }
439 }
440
441 /*
442  * Guarantee that the kzalloc'd memory is cacheline aligned.
443  */
444 void *
445 xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
446 {
447         /* see if kzalloc will give us cachline aligned memory by default */
448         *base = kzalloc(size, flags);
449         if (*base == NULL)
450                 return NULL;
451
452         if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
453                 return *base;
454
455         kfree(*base);
456
457         /* nope, we'll have to do it ourselves */
458         *base = kzalloc(size + L1_CACHE_BYTES, flags);
459         if (*base == NULL)
460                 return NULL;
461
462         return (void *)L1_CACHE_ALIGN((u64)*base);
463 }
464
465 /*
466  * Setup the channel structures necessary to support XPartition Communication
467  * between the specified remote partition and the local one.
468  */
469 static enum xp_retval
470 xpc_setup_ch_structures(struct xpc_partition *part)
471 {
472         enum xp_retval ret;
473         int ch_number;
474         struct xpc_channel *ch;
475         short partid = XPC_PARTID(part);
476
477         /*
478          * Allocate all of the channel structures as a contiguous chunk of
479          * memory.
480          */
481         DBUG_ON(part->channels != NULL);
482         part->channels = kzalloc(sizeof(struct xpc_channel) * XPC_MAX_NCHANNELS,
483                                  GFP_KERNEL);
484         if (part->channels == NULL) {
485                 dev_err(xpc_chan, "can't get memory for channels\n");
486                 return xpNoMemory;
487         }
488
489         /* allocate the remote open and close args */
490
491         part->remote_openclose_args =
492             xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
493                                           GFP_KERNEL, &part->
494                                           remote_openclose_args_base);
495         if (part->remote_openclose_args == NULL) {
496                 dev_err(xpc_chan, "can't get memory for remote connect args\n");
497                 ret = xpNoMemory;
498                 goto out_1;
499         }
500
501         part->chctl.all_flags = 0;
502         spin_lock_init(&part->chctl_lock);
503
504         atomic_set(&part->channel_mgr_requests, 1);
505         init_waitqueue_head(&part->channel_mgr_wq);
506
507         part->nchannels = XPC_MAX_NCHANNELS;
508
509         atomic_set(&part->nchannels_active, 0);
510         atomic_set(&part->nchannels_engaged, 0);
511
512         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
513                 ch = &part->channels[ch_number];
514
515                 ch->partid = partid;
516                 ch->number = ch_number;
517                 ch->flags = XPC_C_DISCONNECTED;
518
519                 atomic_set(&ch->kthreads_assigned, 0);
520                 atomic_set(&ch->kthreads_idle, 0);
521                 atomic_set(&ch->kthreads_active, 0);
522
523                 atomic_set(&ch->references, 0);
524                 atomic_set(&ch->n_to_notify, 0);
525
526                 spin_lock_init(&ch->lock);
527                 init_completion(&ch->wdisconnect_wait);
528
529                 atomic_set(&ch->n_on_msg_allocate_wq, 0);
530                 init_waitqueue_head(&ch->msg_allocate_wq);
531                 init_waitqueue_head(&ch->idle_wq);
532         }
533
534         ret = xpc_setup_ch_structures_sn(part);
535         if (ret != xpSuccess)
536                 goto out_2;
537
538         /*
539          * With the setting of the partition setup_state to XPC_P_SS_SETUP,
540          * we're declaring that this partition is ready to go.
541          */
542         part->setup_state = XPC_P_SS_SETUP;
543
544         return xpSuccess;
545
546         /* setup of ch structures failed */
547 out_2:
548         kfree(part->remote_openclose_args_base);
549         part->remote_openclose_args = NULL;
550 out_1:
551         kfree(part->channels);
552         part->channels = NULL;
553         return ret;
554 }
555
556 /*
557  * Teardown the channel structures necessary to support XPartition Communication
558  * between the specified remote partition and the local one.
559  */
560 static void
561 xpc_teardown_ch_structures(struct xpc_partition *part)
562 {
563         DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
564         DBUG_ON(atomic_read(&part->nchannels_active) != 0);
565
566         /*
567          * Make this partition inaccessible to local processes by marking it
568          * as no longer setup. Then wait before proceeding with the teardown
569          * until all existing references cease.
570          */
571         DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
572         part->setup_state = XPC_P_SS_WTEARDOWN;
573
574         wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
575
576         /* now we can begin tearing down the infrastructure */
577
578         xpc_teardown_ch_structures_sn(part);
579
580         kfree(part->remote_openclose_args_base);
581         part->remote_openclose_args = NULL;
582         kfree(part->channels);
583         part->channels = NULL;
584
585         part->setup_state = XPC_P_SS_TORNDOWN;
586 }
587
588 /*
589  * When XPC HB determines that a partition has come up, it will create a new
590  * kthread and that kthread will call this function to attempt to set up the
591  * basic infrastructure used for Cross Partition Communication with the newly
592  * upped partition.
593  *
594  * The kthread that was created by XPC HB and which setup the XPC
595  * infrastructure will remain assigned to the partition becoming the channel
596  * manager for that partition until the partition is deactivating, at which
597  * time the kthread will teardown the XPC infrastructure and then exit.
598  */
599 static int
600 xpc_activating(void *__partid)
601 {
602         short partid = (u64)__partid;
603         struct xpc_partition *part = &xpc_partitions[partid];
604         unsigned long irq_flags;
605
606         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
607
608         spin_lock_irqsave(&part->act_lock, irq_flags);
609
610         if (part->act_state == XPC_P_AS_DEACTIVATING) {
611                 part->act_state = XPC_P_AS_INACTIVE;
612                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
613                 part->remote_rp_pa = 0;
614                 return 0;
615         }
616
617         /* indicate the thread is activating */
618         DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
619         part->act_state = XPC_P_AS_ACTIVATING;
620
621         XPC_SET_REASON(part, 0, 0);
622         spin_unlock_irqrestore(&part->act_lock, irq_flags);
623
624         dev_dbg(xpc_part, "activating partition %d\n", partid);
625
626         xpc_allow_hb(partid);
627
628         if (xpc_setup_ch_structures(part) == xpSuccess) {
629                 (void)xpc_part_ref(part);       /* this will always succeed */
630
631                 if (xpc_make_first_contact(part) == xpSuccess) {
632                         xpc_mark_partition_active(part);
633                         xpc_channel_mgr(part);
634                         /* won't return until partition is deactivating */
635                 }
636
637                 xpc_part_deref(part);
638                 xpc_teardown_ch_structures(part);
639         }
640
641         xpc_disallow_hb(partid);
642         xpc_mark_partition_inactive(part);
643
644         if (part->reason == xpReactivating) {
645                 /* interrupting ourselves results in activating partition */
646                 xpc_request_partition_reactivation(part);
647         }
648
649         return 0;
650 }
651
652 void
653 xpc_activate_partition(struct xpc_partition *part)
654 {
655         short partid = XPC_PARTID(part);
656         unsigned long irq_flags;
657         struct task_struct *kthread;
658
659         spin_lock_irqsave(&part->act_lock, irq_flags);
660
661         DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
662
663         part->act_state = XPC_P_AS_ACTIVATION_REQ;
664         XPC_SET_REASON(part, xpCloneKThread, __LINE__);
665
666         spin_unlock_irqrestore(&part->act_lock, irq_flags);
667
668         kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
669                               partid);
670         if (IS_ERR(kthread)) {
671                 spin_lock_irqsave(&part->act_lock, irq_flags);
672                 part->act_state = XPC_P_AS_INACTIVE;
673                 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
674                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
675         }
676 }
677
678 void
679 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
680 {
681         int idle = atomic_read(&ch->kthreads_idle);
682         int assigned = atomic_read(&ch->kthreads_assigned);
683         int wakeup;
684
685         DBUG_ON(needed <= 0);
686
687         if (idle > 0) {
688                 wakeup = (needed > idle) ? idle : needed;
689                 needed -= wakeup;
690
691                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
692                         "channel=%d\n", wakeup, ch->partid, ch->number);
693
694                 /* only wakeup the requested number of kthreads */
695                 wake_up_nr(&ch->idle_wq, wakeup);
696         }
697
698         if (needed <= 0)
699                 return;
700
701         if (needed + assigned > ch->kthreads_assigned_limit) {
702                 needed = ch->kthreads_assigned_limit - assigned;
703                 if (needed <= 0)
704                         return;
705         }
706
707         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
708                 needed, ch->partid, ch->number);
709
710         xpc_create_kthreads(ch, needed, 0);
711 }
712
713 /*
714  * This function is where XPC's kthreads wait for messages to deliver.
715  */
716 static void
717 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
718 {
719         do {
720                 /* deliver messages to their intended recipients */
721
722                 while (xpc_n_of_deliverable_payloads(ch) > 0 &&
723                        !(ch->flags & XPC_C_DISCONNECTING)) {
724                         xpc_deliver_payload(ch);
725                 }
726
727                 if (atomic_inc_return(&ch->kthreads_idle) >
728                     ch->kthreads_idle_limit) {
729                         /* too many idle kthreads on this channel */
730                         atomic_dec(&ch->kthreads_idle);
731                         break;
732                 }
733
734                 dev_dbg(xpc_chan, "idle kthread calling "
735                         "wait_event_interruptible_exclusive()\n");
736
737                 (void)wait_event_interruptible_exclusive(ch->idle_wq,
738                                 (xpc_n_of_deliverable_payloads(ch) > 0 ||
739                                  (ch->flags & XPC_C_DISCONNECTING)));
740
741                 atomic_dec(&ch->kthreads_idle);
742
743         } while (!(ch->flags & XPC_C_DISCONNECTING));
744 }
745
746 static int
747 xpc_kthread_start(void *args)
748 {
749         short partid = XPC_UNPACK_ARG1(args);
750         u16 ch_number = XPC_UNPACK_ARG2(args);
751         struct xpc_partition *part = &xpc_partitions[partid];
752         struct xpc_channel *ch;
753         int n_needed;
754         unsigned long irq_flags;
755
756         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
757                 partid, ch_number);
758
759         ch = &part->channels[ch_number];
760
761         if (!(ch->flags & XPC_C_DISCONNECTING)) {
762
763                 /* let registerer know that connection has been established */
764
765                 spin_lock_irqsave(&ch->lock, irq_flags);
766                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
767                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
768                         spin_unlock_irqrestore(&ch->lock, irq_flags);
769
770                         xpc_connected_callout(ch);
771
772                         spin_lock_irqsave(&ch->lock, irq_flags);
773                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
774                         spin_unlock_irqrestore(&ch->lock, irq_flags);
775
776                         /*
777                          * It is possible that while the callout was being
778                          * made that the remote partition sent some messages.
779                          * If that is the case, we may need to activate
780                          * additional kthreads to help deliver them. We only
781                          * need one less than total #of messages to deliver.
782                          */
783                         n_needed = xpc_n_of_deliverable_payloads(ch) - 1;
784                         if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
785                                 xpc_activate_kthreads(ch, n_needed);
786
787                 } else {
788                         spin_unlock_irqrestore(&ch->lock, irq_flags);
789                 }
790
791                 xpc_kthread_waitmsgs(part, ch);
792         }
793
794         /* let registerer know that connection is disconnecting */
795
796         spin_lock_irqsave(&ch->lock, irq_flags);
797         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
798             !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
799                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
800                 spin_unlock_irqrestore(&ch->lock, irq_flags);
801
802                 xpc_disconnect_callout(ch, xpDisconnecting);
803
804                 spin_lock_irqsave(&ch->lock, irq_flags);
805                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
806         }
807         spin_unlock_irqrestore(&ch->lock, irq_flags);
808
809         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
810             atomic_dec_return(&part->nchannels_engaged) == 0) {
811                 xpc_indicate_partition_disengaged(part);
812         }
813
814         xpc_msgqueue_deref(ch);
815
816         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
817                 partid, ch_number);
818
819         xpc_part_deref(part);
820         return 0;
821 }
822
823 /*
824  * For each partition that XPC has established communications with, there is
825  * a minimum of one kernel thread assigned to perform any operation that
826  * may potentially sleep or block (basically the callouts to the asynchronous
827  * functions registered via xpc_connect()).
828  *
829  * Additional kthreads are created and destroyed by XPC as the workload
830  * demands.
831  *
832  * A kthread is assigned to one of the active channels that exists for a given
833  * partition.
834  */
835 void
836 xpc_create_kthreads(struct xpc_channel *ch, int needed,
837                     int ignore_disconnecting)
838 {
839         unsigned long irq_flags;
840         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
841         struct xpc_partition *part = &xpc_partitions[ch->partid];
842         struct task_struct *kthread;
843
844         while (needed-- > 0) {
845
846                 /*
847                  * The following is done on behalf of the newly created
848                  * kthread. That kthread is responsible for doing the
849                  * counterpart to the following before it exits.
850                  */
851                 if (ignore_disconnecting) {
852                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
853                                 /* kthreads assigned had gone to zero */
854                                 BUG_ON(!(ch->flags &
855                                          XPC_C_DISCONNECTINGCALLOUT_MADE));
856                                 break;
857                         }
858
859                 } else if (ch->flags & XPC_C_DISCONNECTING) {
860                         break;
861
862                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
863                            atomic_inc_return(&part->nchannels_engaged) == 1) {
864                                 xpc_indicate_partition_engaged(part);
865                 }
866                 (void)xpc_part_ref(part);
867                 xpc_msgqueue_ref(ch);
868
869                 kthread = kthread_run(xpc_kthread_start, (void *)args,
870                                       "xpc%02dc%d", ch->partid, ch->number);
871                 if (IS_ERR(kthread)) {
872                         /* the fork failed */
873
874                         /*
875                          * NOTE: if (ignore_disconnecting &&
876                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
877                          * then we'll deadlock if all other kthreads assigned
878                          * to this channel are blocked in the channel's
879                          * registerer, because the only thing that will unblock
880                          * them is the xpDisconnecting callout that this
881                          * failed kthread_run() would have made.
882                          */
883
884                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
885                             atomic_dec_return(&part->nchannels_engaged) == 0) {
886                                 xpc_indicate_partition_disengaged(part);
887                         }
888                         xpc_msgqueue_deref(ch);
889                         xpc_part_deref(part);
890
891                         if (atomic_read(&ch->kthreads_assigned) <
892                             ch->kthreads_idle_limit) {
893                                 /*
894                                  * Flag this as an error only if we have an
895                                  * insufficient #of kthreads for the channel
896                                  * to function.
897                                  */
898                                 spin_lock_irqsave(&ch->lock, irq_flags);
899                                 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
900                                                        &irq_flags);
901                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
902                         }
903                         break;
904                 }
905         }
906 }
907
908 void
909 xpc_disconnect_wait(int ch_number)
910 {
911         unsigned long irq_flags;
912         short partid;
913         struct xpc_partition *part;
914         struct xpc_channel *ch;
915         int wakeup_channel_mgr;
916
917         /* now wait for all callouts to the caller's function to cease */
918         for (partid = 0; partid < xp_max_npartitions; partid++) {
919                 part = &xpc_partitions[partid];
920
921                 if (!xpc_part_ref(part))
922                         continue;
923
924                 ch = &part->channels[ch_number];
925
926                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
927                         xpc_part_deref(part);
928                         continue;
929                 }
930
931                 wait_for_completion(&ch->wdisconnect_wait);
932
933                 spin_lock_irqsave(&ch->lock, irq_flags);
934                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
935                 wakeup_channel_mgr = 0;
936
937                 if (ch->delayed_chctl_flags) {
938                         if (part->act_state != XPC_P_AS_DEACTIVATING) {
939                                 spin_lock(&part->chctl_lock);
940                                 part->chctl.flags[ch->number] |=
941                                     ch->delayed_chctl_flags;
942                                 spin_unlock(&part->chctl_lock);
943                                 wakeup_channel_mgr = 1;
944                         }
945                         ch->delayed_chctl_flags = 0;
946                 }
947
948                 ch->flags &= ~XPC_C_WDISCONNECT;
949                 spin_unlock_irqrestore(&ch->lock, irq_flags);
950
951                 if (wakeup_channel_mgr)
952                         xpc_wakeup_channel_mgr(part);
953
954                 xpc_part_deref(part);
955         }
956 }
957
958 static int
959 xpc_setup_partitions(void)
960 {
961         short partid;
962         struct xpc_partition *part;
963
964         xpc_partitions = kzalloc(sizeof(struct xpc_partition) *
965                                  xp_max_npartitions, GFP_KERNEL);
966         if (xpc_partitions == NULL) {
967                 dev_err(xpc_part, "can't get memory for partition structure\n");
968                 return -ENOMEM;
969         }
970
971         /*
972          * The first few fields of each entry of xpc_partitions[] need to
973          * be initialized now so that calls to xpc_connect() and
974          * xpc_disconnect() can be made prior to the activation of any remote
975          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
976          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
977          * PARTITION HAS BEEN ACTIVATED.
978          */
979         for (partid = 0; partid < xp_max_npartitions; partid++) {
980                 part = &xpc_partitions[partid];
981
982                 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
983
984                 part->activate_IRQ_rcvd = 0;
985                 spin_lock_init(&part->act_lock);
986                 part->act_state = XPC_P_AS_INACTIVE;
987                 XPC_SET_REASON(part, 0, 0);
988
989                 init_timer(&part->disengage_timer);
990                 part->disengage_timer.function =
991                     xpc_timeout_partition_disengage;
992                 part->disengage_timer.data = (unsigned long)part;
993
994                 part->setup_state = XPC_P_SS_UNSET;
995                 init_waitqueue_head(&part->teardown_wq);
996                 atomic_set(&part->references, 0);
997         }
998
999         return xpc_setup_partitions_sn();
1000 }
1001
1002 static void
1003 xpc_teardown_partitions(void)
1004 {
1005         xpc_teardown_partitions_sn();
1006         kfree(xpc_partitions);
1007 }
1008
1009 static void
1010 xpc_do_exit(enum xp_retval reason)
1011 {
1012         short partid;
1013         int active_part_count, printed_waiting_msg = 0;
1014         struct xpc_partition *part;
1015         unsigned long printmsg_time, disengage_timeout = 0;
1016
1017         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
1018         DBUG_ON(xpc_exiting == 1);
1019
1020         /*
1021          * Let the heartbeat checker thread and the discovery thread
1022          * (if one is running) know that they should exit. Also wake up
1023          * the heartbeat checker thread in case it's sleeping.
1024          */
1025         xpc_exiting = 1;
1026         wake_up_interruptible(&xpc_activate_IRQ_wq);
1027
1028         /* wait for the discovery thread to exit */
1029         wait_for_completion(&xpc_discovery_exited);
1030
1031         /* wait for the heartbeat checker thread to exit */
1032         wait_for_completion(&xpc_hb_checker_exited);
1033
1034         /* sleep for a 1/3 of a second or so */
1035         (void)msleep_interruptible(300);
1036
1037         /* wait for all partitions to become inactive */
1038
1039         printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1040         xpc_disengage_timedout = 0;
1041
1042         do {
1043                 active_part_count = 0;
1044
1045                 for (partid = 0; partid < xp_max_npartitions; partid++) {
1046                         part = &xpc_partitions[partid];
1047
1048                         if (xpc_partition_disengaged(part) &&
1049                             part->act_state == XPC_P_AS_INACTIVE) {
1050                                 continue;
1051                         }
1052
1053                         active_part_count++;
1054
1055                         XPC_DEACTIVATE_PARTITION(part, reason);
1056
1057                         if (part->disengage_timeout > disengage_timeout)
1058                                 disengage_timeout = part->disengage_timeout;
1059                 }
1060
1061                 if (xpc_any_partition_engaged()) {
1062                         if (time_is_before_jiffies(printmsg_time)) {
1063                                 dev_info(xpc_part, "waiting for remote "
1064                                          "partitions to deactivate, timeout in "
1065                                          "%ld seconds\n", (disengage_timeout -
1066                                          jiffies) / HZ);
1067                                 printmsg_time = jiffies +
1068                                     (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1069                                 printed_waiting_msg = 1;
1070                         }
1071
1072                 } else if (active_part_count > 0) {
1073                         if (printed_waiting_msg) {
1074                                 dev_info(xpc_part, "waiting for local partition"
1075                                          " to deactivate\n");
1076                                 printed_waiting_msg = 0;
1077                         }
1078
1079                 } else {
1080                         if (!xpc_disengage_timedout) {
1081                                 dev_info(xpc_part, "all partitions have "
1082                                          "deactivated\n");
1083                         }
1084                         break;
1085                 }
1086
1087                 /* sleep for a 1/3 of a second or so */
1088                 (void)msleep_interruptible(300);
1089
1090         } while (1);
1091
1092         DBUG_ON(xpc_any_partition_engaged());
1093
1094         xpc_teardown_rsvd_page();
1095
1096         if (reason == xpUnloading) {
1097                 (void)unregister_die_notifier(&xpc_die_notifier);
1098                 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1099         }
1100
1101         /* clear the interface to XPC's functions */
1102         xpc_clear_interface();
1103
1104         if (xpc_sysctl)
1105                 unregister_sysctl_table(xpc_sysctl);
1106
1107         xpc_teardown_partitions();
1108
1109         if (is_shub())
1110                 xpc_exit_sn2();
1111         else if (is_uv())
1112                 xpc_exit_uv();
1113 }
1114
1115 /*
1116  * This function is called when the system is being rebooted.
1117  */
1118 static int
1119 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1120 {
1121         enum xp_retval reason;
1122
1123         switch (event) {
1124         case SYS_RESTART:
1125                 reason = xpSystemReboot;
1126                 break;
1127         case SYS_HALT:
1128                 reason = xpSystemHalt;
1129                 break;
1130         case SYS_POWER_OFF:
1131                 reason = xpSystemPoweroff;
1132                 break;
1133         default:
1134                 reason = xpSystemGoingDown;
1135         }
1136
1137         xpc_do_exit(reason);
1138         return NOTIFY_DONE;
1139 }
1140
1141 /*
1142  * Notify other partitions to deactivate from us by first disengaging from all
1143  * references to our memory.
1144  */
1145 static void
1146 xpc_die_deactivate(void)
1147 {
1148         struct xpc_partition *part;
1149         short partid;
1150         int any_engaged;
1151         long keep_waiting;
1152         long wait_to_print;
1153
1154         /* keep xpc_hb_checker thread from doing anything (just in case) */
1155         xpc_exiting = 1;
1156
1157         xpc_disallow_all_hbs(); /*indicate we're deactivated */
1158
1159         for (partid = 0; partid < xp_max_npartitions; partid++) {
1160                 part = &xpc_partitions[partid];
1161
1162                 if (xpc_partition_engaged(partid) ||
1163                     part->act_state != XPC_P_AS_INACTIVE) {
1164                         xpc_request_partition_deactivation(part);
1165                         xpc_indicate_partition_disengaged(part);
1166                 }
1167         }
1168
1169         /*
1170          * Though we requested that all other partitions deactivate from us,
1171          * we only wait until they've all disengaged or we've reached the
1172          * defined timelimit.
1173          *
1174          * Given that one iteration through the following while-loop takes
1175          * approximately 200 microseconds, calculate the #of loops to take
1176          * before bailing and the #of loops before printing a waiting message.
1177          */
1178         keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1179         wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1180
1181         while (1) {
1182                 any_engaged = xpc_any_partition_engaged();
1183                 if (!any_engaged) {
1184                         dev_info(xpc_part, "all partitions have deactivated\n");
1185                         break;
1186                 }
1187
1188                 if (!keep_waiting--) {
1189                         for (partid = 0; partid < xp_max_npartitions;
1190                              partid++) {
1191                                 if (xpc_partition_engaged(partid)) {
1192                                         dev_info(xpc_part, "deactivate from "
1193                                                  "remote partition %d timed "
1194                                                  "out\n", partid);
1195                                 }
1196                         }
1197                         break;
1198                 }
1199
1200                 if (!wait_to_print--) {
1201                         dev_info(xpc_part, "waiting for remote partitions to "
1202                                  "deactivate, timeout in %ld seconds\n",
1203                                  keep_waiting / (1000 * 5));
1204                         wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1205                             1000 * 5;
1206                 }
1207
1208                 udelay(200);
1209         }
1210 }
1211
1212 /*
1213  * This function is called when the system is being restarted or halted due
1214  * to some sort of system failure. If this is the case we need to notify the
1215  * other partitions to disengage from all references to our memory.
1216  * This function can also be called when our heartbeater could be offlined
1217  * for a time. In this case we need to notify other partitions to not worry
1218  * about the lack of a heartbeat.
1219  */
1220 static int
1221 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1222 {
1223 #ifdef CONFIG_IA64              /* !!! temporary kludge */
1224         switch (event) {
1225         case DIE_MACHINE_RESTART:
1226         case DIE_MACHINE_HALT:
1227                 xpc_die_deactivate();
1228                 break;
1229
1230         case DIE_KDEBUG_ENTER:
1231                 /* Should lack of heartbeat be ignored by other partitions? */
1232                 if (!xpc_kdebug_ignore)
1233                         break;
1234
1235                 /* fall through */
1236         case DIE_MCA_MONARCH_ENTER:
1237         case DIE_INIT_MONARCH_ENTER:
1238                 xpc_offline_heartbeat();
1239                 break;
1240
1241         case DIE_KDEBUG_LEAVE:
1242                 /* Is lack of heartbeat being ignored by other partitions? */
1243                 if (!xpc_kdebug_ignore)
1244                         break;
1245
1246                 /* fall through */
1247         case DIE_MCA_MONARCH_LEAVE:
1248         case DIE_INIT_MONARCH_LEAVE:
1249                 xpc_online_heartbeat();
1250                 break;
1251         }
1252 #else
1253         xpc_die_deactivate();
1254 #endif
1255
1256         return NOTIFY_DONE;
1257 }
1258
1259 int __init
1260 xpc_init(void)
1261 {
1262         int ret;
1263         struct task_struct *kthread;
1264
1265         dev_set_name(xpc_part, "part");
1266         dev_set_name(xpc_chan, "chan");
1267
1268         if (is_shub()) {
1269                 /*
1270                  * The ia64-sn2 architecture supports at most 64 partitions.
1271                  * And the inability to unregister remote amos restricts us
1272                  * further to only support exactly 64 partitions on this
1273                  * architecture, no less.
1274                  */
1275                 if (xp_max_npartitions != 64) {
1276                         dev_err(xpc_part, "max #of partitions not set to 64\n");
1277                         ret = -EINVAL;
1278                 } else {
1279                         ret = xpc_init_sn2();
1280                 }
1281
1282         } else if (is_uv()) {
1283                 ret = xpc_init_uv();
1284
1285         } else {
1286                 ret = -ENODEV;
1287         }
1288
1289         if (ret != 0)
1290                 return ret;
1291
1292         ret = xpc_setup_partitions();
1293         if (ret != 0) {
1294                 dev_err(xpc_part, "can't get memory for partition structure\n");
1295                 goto out_1;
1296         }
1297
1298         xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1299
1300         /*
1301          * Fill the partition reserved page with the information needed by
1302          * other partitions to discover we are alive and establish initial
1303          * communications.
1304          */
1305         ret = xpc_setup_rsvd_page();
1306         if (ret != 0) {
1307                 dev_err(xpc_part, "can't setup our reserved page\n");
1308                 goto out_2;
1309         }
1310
1311         /* add ourselves to the reboot_notifier_list */
1312         ret = register_reboot_notifier(&xpc_reboot_notifier);
1313         if (ret != 0)
1314                 dev_warn(xpc_part, "can't register reboot notifier\n");
1315
1316         /* add ourselves to the die_notifier list */
1317         ret = register_die_notifier(&xpc_die_notifier);
1318         if (ret != 0)
1319                 dev_warn(xpc_part, "can't register die notifier\n");
1320
1321         /*
1322          * The real work-horse behind xpc.  This processes incoming
1323          * interrupts and monitors remote heartbeats.
1324          */
1325         kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1326         if (IS_ERR(kthread)) {
1327                 dev_err(xpc_part, "failed while forking hb check thread\n");
1328                 ret = -EBUSY;
1329                 goto out_3;
1330         }
1331
1332         /*
1333          * Startup a thread that will attempt to discover other partitions to
1334          * activate based on info provided by SAL. This new thread is short
1335          * lived and will exit once discovery is complete.
1336          */
1337         kthread = kthread_run(xpc_initiate_discovery, NULL,
1338                               XPC_DISCOVERY_THREAD_NAME);
1339         if (IS_ERR(kthread)) {
1340                 dev_err(xpc_part, "failed while forking discovery thread\n");
1341
1342                 /* mark this new thread as a non-starter */
1343                 complete(&xpc_discovery_exited);
1344
1345                 xpc_do_exit(xpUnloading);
1346                 return -EBUSY;
1347         }
1348
1349         /* set the interface to point at XPC's functions */
1350         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1351                           xpc_initiate_send, xpc_initiate_send_notify,
1352                           xpc_initiate_received, xpc_initiate_partid_to_nasids);
1353
1354         return 0;
1355
1356         /* initialization was not successful */
1357 out_3:
1358         xpc_teardown_rsvd_page();
1359
1360         (void)unregister_die_notifier(&xpc_die_notifier);
1361         (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1362 out_2:
1363         if (xpc_sysctl)
1364                 unregister_sysctl_table(xpc_sysctl);
1365
1366         xpc_teardown_partitions();
1367 out_1:
1368         if (is_shub())
1369                 xpc_exit_sn2();
1370         else if (is_uv())
1371                 xpc_exit_uv();
1372         return ret;
1373 }
1374
1375 module_init(xpc_init);
1376
1377 void __exit
1378 xpc_exit(void)
1379 {
1380         xpc_do_exit(xpUnloading);
1381 }
1382
1383 module_exit(xpc_exit);
1384
1385 MODULE_AUTHOR("Silicon Graphics, Inc.");
1386 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1387 MODULE_LICENSE("GPL");
1388
1389 module_param(xpc_hb_interval, int, 0);
1390 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1391                  "heartbeat increments.");
1392
1393 module_param(xpc_hb_check_interval, int, 0);
1394 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1395                  "heartbeat checks.");
1396
1397 module_param(xpc_disengage_timelimit, int, 0);
1398 MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1399                  "for disengage to complete.");
1400
1401 module_param(xpc_kdebug_ignore, int, 0);
1402 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1403                  "other partitions when dropping into kdebug.");