1ab9fda87fabaf581fcb5bf6e6151da7b2ca1e27
[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) 2004-2008 Silicon Graphics, Inc.  All Rights Reserved.
7  */
8
9 /*
10  * Cross Partition Communication (XPC) support - standard version.
11  *
12  *      XPC provides a message passing capability that crosses partition
13  *      boundaries. This module is made up of two parts:
14  *
15  *          partition   This part detects the presence/absence of other
16  *                      partitions. It provides a heartbeat and monitors
17  *                      the heartbeats of other partitions.
18  *
19  *          channel     This part manages the channels and sends/receives
20  *                      messages across them to/from other partitions.
21  *
22  *      There are a couple of additional functions residing in XP, which
23  *      provide an interface to XPC for its users.
24  *
25  *
26  *      Caveats:
27  *
28  *        . 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 void *xpc_heartbeating_to_mask;
154
155 /* notification that the xpc_hb_checker thread has exited */
156 static DECLARE_COMPLETION(xpc_hb_checker_exited);
157
158 /* notification that the xpc_discovery thread has exited */
159 static DECLARE_COMPLETION(xpc_discovery_exited);
160
161 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
162
163 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
164 static struct notifier_block xpc_reboot_notifier = {
165         .notifier_call = xpc_system_reboot,
166 };
167
168 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
169 static struct notifier_block xpc_die_notifier = {
170         .notifier_call = xpc_system_die,
171 };
172
173 int (*xpc_setup_partitions_sn) (void);
174 void (*xpc_teardown_partitions_sn) (void);
175 enum xp_retval (*xpc_get_partition_rsvd_page_pa) (void *buf, u64 *cookie,
176                                                   unsigned long *rp_pa,
177                                                   size_t *len);
178 int (*xpc_setup_rsvd_page_sn) (struct xpc_rsvd_page *rp);
179 void (*xpc_heartbeat_init) (void);
180 void (*xpc_heartbeat_exit) (void);
181 void (*xpc_increment_heartbeat) (void);
182 void (*xpc_offline_heartbeat) (void);
183 void (*xpc_online_heartbeat) (void);
184 enum xp_retval (*xpc_get_remote_heartbeat) (struct xpc_partition *part);
185
186 enum xp_retval (*xpc_make_first_contact) (struct xpc_partition *part);
187 void (*xpc_notify_senders_of_disconnect) (struct xpc_channel *ch);
188 u64 (*xpc_get_chctl_all_flags) (struct xpc_partition *part);
189 enum xp_retval (*xpc_setup_msg_structures) (struct xpc_channel *ch);
190 void (*xpc_teardown_msg_structures) (struct xpc_channel *ch);
191 void (*xpc_process_msg_chctl_flags) (struct xpc_partition *part, int ch_number);
192 int (*xpc_n_of_deliverable_payloads) (struct xpc_channel *ch);
193 void *(*xpc_get_deliverable_payload) (struct xpc_channel *ch);
194
195 void (*xpc_request_partition_activation) (struct xpc_rsvd_page *remote_rp,
196                                           unsigned long remote_rp_pa,
197                                           int nasid);
198 void (*xpc_request_partition_reactivation) (struct xpc_partition *part);
199 void (*xpc_request_partition_deactivation) (struct xpc_partition *part);
200 void (*xpc_cancel_partition_deactivation_request) (struct xpc_partition *part);
201
202 void (*xpc_process_activate_IRQ_rcvd) (void);
203 enum xp_retval (*xpc_setup_ch_structures_sn) (struct xpc_partition *part);
204 void (*xpc_teardown_ch_structures_sn) (struct xpc_partition *part);
205
206 void (*xpc_indicate_partition_engaged) (struct xpc_partition *part);
207 int (*xpc_partition_engaged) (short partid);
208 int (*xpc_any_partition_engaged) (void);
209 void (*xpc_indicate_partition_disengaged) (struct xpc_partition *part);
210 void (*xpc_assume_partition_disengaged) (short partid);
211
212 void (*xpc_send_chctl_closerequest) (struct xpc_channel *ch,
213                                      unsigned long *irq_flags);
214 void (*xpc_send_chctl_closereply) (struct xpc_channel *ch,
215                                    unsigned long *irq_flags);
216 void (*xpc_send_chctl_openrequest) (struct xpc_channel *ch,
217                                     unsigned long *irq_flags);
218 void (*xpc_send_chctl_openreply) (struct xpc_channel *ch,
219                                   unsigned long *irq_flags);
220
221 enum xp_retval (*xpc_save_remote_msgqueue_pa) (struct xpc_channel *ch,
222                                                unsigned long msgqueue_pa);
223
224 enum xp_retval (*xpc_send_payload) (struct xpc_channel *ch, u32 flags,
225                                     void *payload, u16 payload_size,
226                                     u8 notify_type, xpc_notify_func func,
227                                     void *key);
228 void (*xpc_received_payload) (struct xpc_channel *ch, void *payload);
229
230 /*
231  * Timer function to enforce the timelimit on the partition disengage.
232  */
233 static void
234 xpc_timeout_partition_disengage(unsigned long data)
235 {
236         struct xpc_partition *part = (struct xpc_partition *)data;
237
238         DBUG_ON(time_is_after_jiffies(part->disengage_timeout));
239
240         (void)xpc_partition_disengaged(part);
241
242         DBUG_ON(part->disengage_timeout != 0);
243         DBUG_ON(xpc_partition_engaged(XPC_PARTID(part)));
244 }
245
246 /*
247  * Timer to produce the heartbeat.  The timer structures function is
248  * already set when this is initially called.  A tunable is used to
249  * specify when the next timeout should occur.
250  */
251 static void
252 xpc_hb_beater(unsigned long dummy)
253 {
254         xpc_increment_heartbeat();
255
256         if (time_is_before_eq_jiffies(xpc_hb_check_timeout))
257                 wake_up_interruptible(&xpc_activate_IRQ_wq);
258
259         xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
260         add_timer(&xpc_hb_timer);
261 }
262
263 static void
264 xpc_start_hb_beater(void)
265 {
266         xpc_heartbeat_init();
267         init_timer(&xpc_hb_timer);
268         xpc_hb_timer.function = xpc_hb_beater;
269         xpc_hb_beater(0);
270 }
271
272 static void
273 xpc_stop_hb_beater(void)
274 {
275         del_timer_sync(&xpc_hb_timer);
276         xpc_heartbeat_exit();
277 }
278
279 /*
280  * At periodic intervals, scan through all active partitions and ensure
281  * their heartbeat is still active.  If not, the partition is deactivated.
282  */
283 static void
284 xpc_check_remote_hb(void)
285 {
286         struct xpc_partition *part;
287         short partid;
288         enum xp_retval ret;
289
290         for (partid = 0; partid < xp_max_npartitions; partid++) {
291
292                 if (xpc_exiting)
293                         break;
294
295                 if (partid == xp_partition_id)
296                         continue;
297
298                 part = &xpc_partitions[partid];
299
300                 if (part->act_state == XPC_P_AS_INACTIVE ||
301                     part->act_state == XPC_P_AS_DEACTIVATING) {
302                         continue;
303                 }
304
305                 ret = xpc_get_remote_heartbeat(part);
306                 if (ret != xpSuccess)
307                         XPC_DEACTIVATE_PARTITION(part, ret);
308         }
309 }
310
311 /*
312  * This thread is responsible for nearly all of the partition
313  * activation/deactivation.
314  */
315 static int
316 xpc_hb_checker(void *ignore)
317 {
318         int force_IRQ = 0;
319
320         /* this thread was marked active by xpc_hb_init() */
321
322         set_cpus_allowed_ptr(current, cpumask_of(XPC_HB_CHECK_CPU));
323
324         /* set our heartbeating to other partitions into motion */
325         xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
326         xpc_start_hb_beater();
327
328         while (!xpc_exiting) {
329
330                 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
331                         "been received\n",
332                         (int)(xpc_hb_check_timeout - jiffies),
333                         xpc_activate_IRQ_rcvd);
334
335                 /* checking of remote heartbeats is skewed by IRQ handling */
336                 if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) {
337                         xpc_hb_check_timeout = jiffies +
338                             (xpc_hb_check_interval * HZ);
339
340                         dev_dbg(xpc_part, "checking remote heartbeats\n");
341                         xpc_check_remote_hb();
342
343                         /*
344                          * On sn2 we need to periodically recheck to ensure no
345                          * IRQ/amo pairs have been missed.
346                          */
347                         if (is_shub())
348                                 force_IRQ = 1;
349                 }
350
351                 /* check for outstanding IRQs */
352                 if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
353                         force_IRQ = 0;
354                         dev_dbg(xpc_part, "processing activate IRQs "
355                                 "received\n");
356                         xpc_process_activate_IRQ_rcvd();
357                 }
358
359                 /* wait for IRQ or timeout */
360                 (void)wait_event_interruptible(xpc_activate_IRQ_wq,
361                                                (time_is_before_eq_jiffies(
362                                                 xpc_hb_check_timeout) ||
363                                                 xpc_activate_IRQ_rcvd > 0 ||
364                                                 xpc_exiting));
365         }
366
367         xpc_stop_hb_beater();
368
369         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
370
371         /* mark this thread as having exited */
372         complete(&xpc_hb_checker_exited);
373         return 0;
374 }
375
376 /*
377  * This thread will attempt to discover other partitions to activate
378  * based on info provided by SAL. This new thread is short lived and
379  * will exit once discovery is complete.
380  */
381 static int
382 xpc_initiate_discovery(void *ignore)
383 {
384         xpc_discovery();
385
386         dev_dbg(xpc_part, "discovery thread is exiting\n");
387
388         /* mark this thread as having exited */
389         complete(&xpc_discovery_exited);
390         return 0;
391 }
392
393 /*
394  * The first kthread assigned to a newly activated partition is the one
395  * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
396  * that kthread until the partition is brought down, at which time that kthread
397  * returns back to XPC HB. (The return of that kthread will signify to XPC HB
398  * that XPC has dismantled all communication infrastructure for the associated
399  * partition.) This kthread becomes the channel manager for that partition.
400  *
401  * Each active partition has a channel manager, who, besides connecting and
402  * disconnecting channels, will ensure that each of the partition's connected
403  * channels has the required number of assigned kthreads to get the work done.
404  */
405 static void
406 xpc_channel_mgr(struct xpc_partition *part)
407 {
408         while (part->act_state != XPC_P_AS_DEACTIVATING ||
409                atomic_read(&part->nchannels_active) > 0 ||
410                !xpc_partition_disengaged(part)) {
411
412                 xpc_process_sent_chctl_flags(part);
413
414                 /*
415                  * Wait until we've been requested to activate kthreads or
416                  * all of the channel's message queues have been torn down or
417                  * a signal is pending.
418                  *
419                  * The channel_mgr_requests is set to 1 after being awakened,
420                  * This is done to prevent the channel mgr from making one pass
421                  * through the loop for each request, since he will
422                  * be servicing all the requests in one pass. The reason it's
423                  * set to 1 instead of 0 is so that other kthreads will know
424                  * that the channel mgr is running and won't bother trying to
425                  * wake him up.
426                  */
427                 atomic_dec(&part->channel_mgr_requests);
428                 (void)wait_event_interruptible(part->channel_mgr_wq,
429                                 (atomic_read(&part->channel_mgr_requests) > 0 ||
430                                  part->chctl.all_flags != 0 ||
431                                  (part->act_state == XPC_P_AS_DEACTIVATING &&
432                                  atomic_read(&part->nchannels_active) == 0 &&
433                                  xpc_partition_disengaged(part))));
434                 atomic_set(&part->channel_mgr_requests, 1);
435         }
436 }
437
438 /*
439  * Guarantee that the kzalloc'd memory is cacheline aligned.
440  */
441 void *
442 xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
443 {
444         /* see if kzalloc will give us cachline aligned memory by default */
445         *base = kzalloc(size, flags);
446         if (*base == NULL)
447                 return NULL;
448
449         if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
450                 return *base;
451
452         kfree(*base);
453
454         /* nope, we'll have to do it ourselves */
455         *base = kzalloc(size + L1_CACHE_BYTES, flags);
456         if (*base == NULL)
457                 return NULL;
458
459         return (void *)L1_CACHE_ALIGN((u64)*base);
460 }
461
462 /*
463  * Setup the channel structures necessary to support XPartition Communication
464  * between the specified remote partition and the local one.
465  */
466 static enum xp_retval
467 xpc_setup_ch_structures(struct xpc_partition *part)
468 {
469         enum xp_retval ret;
470         int ch_number;
471         struct xpc_channel *ch;
472         short partid = XPC_PARTID(part);
473
474         /*
475          * Allocate all of the channel structures as a contiguous chunk of
476          * memory.
477          */
478         DBUG_ON(part->channels != NULL);
479         part->channels = kzalloc(sizeof(struct xpc_channel) * XPC_MAX_NCHANNELS,
480                                  GFP_KERNEL);
481         if (part->channels == NULL) {
482                 dev_err(xpc_chan, "can't get memory for channels\n");
483                 return xpNoMemory;
484         }
485
486         /* allocate the remote open and close args */
487
488         part->remote_openclose_args =
489             xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
490                                           GFP_KERNEL, &part->
491                                           remote_openclose_args_base);
492         if (part->remote_openclose_args == NULL) {
493                 dev_err(xpc_chan, "can't get memory for remote connect args\n");
494                 ret = xpNoMemory;
495                 goto out_1;
496         }
497
498         part->chctl.all_flags = 0;
499         spin_lock_init(&part->chctl_lock);
500
501         atomic_set(&part->channel_mgr_requests, 1);
502         init_waitqueue_head(&part->channel_mgr_wq);
503
504         part->nchannels = XPC_MAX_NCHANNELS;
505
506         atomic_set(&part->nchannels_active, 0);
507         atomic_set(&part->nchannels_engaged, 0);
508
509         for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
510                 ch = &part->channels[ch_number];
511
512                 ch->partid = partid;
513                 ch->number = ch_number;
514                 ch->flags = XPC_C_DISCONNECTED;
515
516                 atomic_set(&ch->kthreads_assigned, 0);
517                 atomic_set(&ch->kthreads_idle, 0);
518                 atomic_set(&ch->kthreads_active, 0);
519
520                 atomic_set(&ch->references, 0);
521                 atomic_set(&ch->n_to_notify, 0);
522
523                 spin_lock_init(&ch->lock);
524                 init_completion(&ch->wdisconnect_wait);
525
526                 atomic_set(&ch->n_on_msg_allocate_wq, 0);
527                 init_waitqueue_head(&ch->msg_allocate_wq);
528                 init_waitqueue_head(&ch->idle_wq);
529         }
530
531         ret = xpc_setup_ch_structures_sn(part);
532         if (ret != xpSuccess)
533                 goto out_2;
534
535         /*
536          * With the setting of the partition setup_state to XPC_P_SS_SETUP,
537          * we're declaring that this partition is ready to go.
538          */
539         part->setup_state = XPC_P_SS_SETUP;
540
541         return xpSuccess;
542
543         /* setup of ch structures failed */
544 out_2:
545         kfree(part->remote_openclose_args_base);
546         part->remote_openclose_args = NULL;
547 out_1:
548         kfree(part->channels);
549         part->channels = NULL;
550         return ret;
551 }
552
553 /*
554  * Teardown the channel structures necessary to support XPartition Communication
555  * between the specified remote partition and the local one.
556  */
557 static void
558 xpc_teardown_ch_structures(struct xpc_partition *part)
559 {
560         DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
561         DBUG_ON(atomic_read(&part->nchannels_active) != 0);
562
563         /*
564          * Make this partition inaccessible to local processes by marking it
565          * as no longer setup. Then wait before proceeding with the teardown
566          * until all existing references cease.
567          */
568         DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
569         part->setup_state = XPC_P_SS_WTEARDOWN;
570
571         wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
572
573         /* now we can begin tearing down the infrastructure */
574
575         xpc_teardown_ch_structures_sn(part);
576
577         kfree(part->remote_openclose_args_base);
578         part->remote_openclose_args = NULL;
579         kfree(part->channels);
580         part->channels = NULL;
581
582         part->setup_state = XPC_P_SS_TORNDOWN;
583 }
584
585 /*
586  * When XPC HB determines that a partition has come up, it will create a new
587  * kthread and that kthread will call this function to attempt to set up the
588  * basic infrastructure used for Cross Partition Communication with the newly
589  * upped partition.
590  *
591  * The kthread that was created by XPC HB and which setup the XPC
592  * infrastructure will remain assigned to the partition becoming the channel
593  * manager for that partition until the partition is deactivating, at which
594  * time the kthread will teardown the XPC infrastructure and then exit.
595  */
596 static int
597 xpc_activating(void *__partid)
598 {
599         short partid = (u64)__partid;
600         struct xpc_partition *part = &xpc_partitions[partid];
601         unsigned long irq_flags;
602
603         DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
604
605         spin_lock_irqsave(&part->act_lock, irq_flags);
606
607         if (part->act_state == XPC_P_AS_DEACTIVATING) {
608                 part->act_state = XPC_P_AS_INACTIVE;
609                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
610                 part->remote_rp_pa = 0;
611                 return 0;
612         }
613
614         /* indicate the thread is activating */
615         DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
616         part->act_state = XPC_P_AS_ACTIVATING;
617
618         XPC_SET_REASON(part, 0, 0);
619         spin_unlock_irqrestore(&part->act_lock, irq_flags);
620
621         dev_dbg(xpc_part, "activating partition %d\n", partid);
622
623         xpc_allow_hb(partid);
624
625         if (xpc_setup_ch_structures(part) == xpSuccess) {
626                 (void)xpc_part_ref(part);       /* this will always succeed */
627
628                 if (xpc_make_first_contact(part) == xpSuccess) {
629                         xpc_mark_partition_active(part);
630                         xpc_channel_mgr(part);
631                         /* won't return until partition is deactivating */
632                 }
633
634                 xpc_part_deref(part);
635                 xpc_teardown_ch_structures(part);
636         }
637
638         xpc_disallow_hb(partid);
639         xpc_mark_partition_inactive(part);
640
641         if (part->reason == xpReactivating) {
642                 /* interrupting ourselves results in activating partition */
643                 xpc_request_partition_reactivation(part);
644         }
645
646         return 0;
647 }
648
649 void
650 xpc_activate_partition(struct xpc_partition *part)
651 {
652         short partid = XPC_PARTID(part);
653         unsigned long irq_flags;
654         struct task_struct *kthread;
655
656         spin_lock_irqsave(&part->act_lock, irq_flags);
657
658         DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
659
660         part->act_state = XPC_P_AS_ACTIVATION_REQ;
661         XPC_SET_REASON(part, xpCloneKThread, __LINE__);
662
663         spin_unlock_irqrestore(&part->act_lock, irq_flags);
664
665         kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
666                               partid);
667         if (IS_ERR(kthread)) {
668                 spin_lock_irqsave(&part->act_lock, irq_flags);
669                 part->act_state = XPC_P_AS_INACTIVE;
670                 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
671                 spin_unlock_irqrestore(&part->act_lock, irq_flags);
672         }
673 }
674
675 void
676 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
677 {
678         int idle = atomic_read(&ch->kthreads_idle);
679         int assigned = atomic_read(&ch->kthreads_assigned);
680         int wakeup;
681
682         DBUG_ON(needed <= 0);
683
684         if (idle > 0) {
685                 wakeup = (needed > idle) ? idle : needed;
686                 needed -= wakeup;
687
688                 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
689                         "channel=%d\n", wakeup, ch->partid, ch->number);
690
691                 /* only wakeup the requested number of kthreads */
692                 wake_up_nr(&ch->idle_wq, wakeup);
693         }
694
695         if (needed <= 0)
696                 return;
697
698         if (needed + assigned > ch->kthreads_assigned_limit) {
699                 needed = ch->kthreads_assigned_limit - assigned;
700                 if (needed <= 0)
701                         return;
702         }
703
704         dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
705                 needed, ch->partid, ch->number);
706
707         xpc_create_kthreads(ch, needed, 0);
708 }
709
710 /*
711  * This function is where XPC's kthreads wait for messages to deliver.
712  */
713 static void
714 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
715 {
716         do {
717                 /* deliver messages to their intended recipients */
718
719                 while (xpc_n_of_deliverable_payloads(ch) > 0 &&
720                        !(ch->flags & XPC_C_DISCONNECTING)) {
721                         xpc_deliver_payload(ch);
722                 }
723
724                 if (atomic_inc_return(&ch->kthreads_idle) >
725                     ch->kthreads_idle_limit) {
726                         /* too many idle kthreads on this channel */
727                         atomic_dec(&ch->kthreads_idle);
728                         break;
729                 }
730
731                 dev_dbg(xpc_chan, "idle kthread calling "
732                         "wait_event_interruptible_exclusive()\n");
733
734                 (void)wait_event_interruptible_exclusive(ch->idle_wq,
735                                 (xpc_n_of_deliverable_payloads(ch) > 0 ||
736                                  (ch->flags & XPC_C_DISCONNECTING)));
737
738                 atomic_dec(&ch->kthreads_idle);
739
740         } while (!(ch->flags & XPC_C_DISCONNECTING));
741 }
742
743 static int
744 xpc_kthread_start(void *args)
745 {
746         short partid = XPC_UNPACK_ARG1(args);
747         u16 ch_number = XPC_UNPACK_ARG2(args);
748         struct xpc_partition *part = &xpc_partitions[partid];
749         struct xpc_channel *ch;
750         int n_needed;
751         unsigned long irq_flags;
752
753         dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
754                 partid, ch_number);
755
756         ch = &part->channels[ch_number];
757
758         if (!(ch->flags & XPC_C_DISCONNECTING)) {
759
760                 /* let registerer know that connection has been established */
761
762                 spin_lock_irqsave(&ch->lock, irq_flags);
763                 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
764                         ch->flags |= XPC_C_CONNECTEDCALLOUT;
765                         spin_unlock_irqrestore(&ch->lock, irq_flags);
766
767                         xpc_connected_callout(ch);
768
769                         spin_lock_irqsave(&ch->lock, irq_flags);
770                         ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
771                         spin_unlock_irqrestore(&ch->lock, irq_flags);
772
773                         /*
774                          * It is possible that while the callout was being
775                          * made that the remote partition sent some messages.
776                          * If that is the case, we may need to activate
777                          * additional kthreads to help deliver them. We only
778                          * need one less than total #of messages to deliver.
779                          */
780                         n_needed = xpc_n_of_deliverable_payloads(ch) - 1;
781                         if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
782                                 xpc_activate_kthreads(ch, n_needed);
783
784                 } else {
785                         spin_unlock_irqrestore(&ch->lock, irq_flags);
786                 }
787
788                 xpc_kthread_waitmsgs(part, ch);
789         }
790
791         /* let registerer know that connection is disconnecting */
792
793         spin_lock_irqsave(&ch->lock, irq_flags);
794         if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
795             !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
796                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
797                 spin_unlock_irqrestore(&ch->lock, irq_flags);
798
799                 xpc_disconnect_callout(ch, xpDisconnecting);
800
801                 spin_lock_irqsave(&ch->lock, irq_flags);
802                 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
803         }
804         spin_unlock_irqrestore(&ch->lock, irq_flags);
805
806         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
807             atomic_dec_return(&part->nchannels_engaged) == 0) {
808                 xpc_indicate_partition_disengaged(part);
809         }
810
811         xpc_msgqueue_deref(ch);
812
813         dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
814                 partid, ch_number);
815
816         xpc_part_deref(part);
817         return 0;
818 }
819
820 /*
821  * For each partition that XPC has established communications with, there is
822  * a minimum of one kernel thread assigned to perform any operation that
823  * may potentially sleep or block (basically the callouts to the asynchronous
824  * functions registered via xpc_connect()).
825  *
826  * Additional kthreads are created and destroyed by XPC as the workload
827  * demands.
828  *
829  * A kthread is assigned to one of the active channels that exists for a given
830  * partition.
831  */
832 void
833 xpc_create_kthreads(struct xpc_channel *ch, int needed,
834                     int ignore_disconnecting)
835 {
836         unsigned long irq_flags;
837         u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
838         struct xpc_partition *part = &xpc_partitions[ch->partid];
839         struct task_struct *kthread;
840
841         while (needed-- > 0) {
842
843                 /*
844                  * The following is done on behalf of the newly created
845                  * kthread. That kthread is responsible for doing the
846                  * counterpart to the following before it exits.
847                  */
848                 if (ignore_disconnecting) {
849                         if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
850                                 /* kthreads assigned had gone to zero */
851                                 BUG_ON(!(ch->flags &
852                                          XPC_C_DISCONNECTINGCALLOUT_MADE));
853                                 break;
854                         }
855
856                 } else if (ch->flags & XPC_C_DISCONNECTING) {
857                         break;
858
859                 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
860                            atomic_inc_return(&part->nchannels_engaged) == 1) {
861                                 xpc_indicate_partition_engaged(part);
862                 }
863                 (void)xpc_part_ref(part);
864                 xpc_msgqueue_ref(ch);
865
866                 kthread = kthread_run(xpc_kthread_start, (void *)args,
867                                       "xpc%02dc%d", ch->partid, ch->number);
868                 if (IS_ERR(kthread)) {
869                         /* the fork failed */
870
871                         /*
872                          * NOTE: if (ignore_disconnecting &&
873                          * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
874                          * then we'll deadlock if all other kthreads assigned
875                          * to this channel are blocked in the channel's
876                          * registerer, because the only thing that will unblock
877                          * them is the xpDisconnecting callout that this
878                          * failed kthread_run() would have made.
879                          */
880
881                         if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
882                             atomic_dec_return(&part->nchannels_engaged) == 0) {
883                                 xpc_indicate_partition_disengaged(part);
884                         }
885                         xpc_msgqueue_deref(ch);
886                         xpc_part_deref(part);
887
888                         if (atomic_read(&ch->kthreads_assigned) <
889                             ch->kthreads_idle_limit) {
890                                 /*
891                                  * Flag this as an error only if we have an
892                                  * insufficient #of kthreads for the channel
893                                  * to function.
894                                  */
895                                 spin_lock_irqsave(&ch->lock, irq_flags);
896                                 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
897                                                        &irq_flags);
898                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
899                         }
900                         break;
901                 }
902         }
903 }
904
905 void
906 xpc_disconnect_wait(int ch_number)
907 {
908         unsigned long irq_flags;
909         short partid;
910         struct xpc_partition *part;
911         struct xpc_channel *ch;
912         int wakeup_channel_mgr;
913
914         /* now wait for all callouts to the caller's function to cease */
915         for (partid = 0; partid < xp_max_npartitions; partid++) {
916                 part = &xpc_partitions[partid];
917
918                 if (!xpc_part_ref(part))
919                         continue;
920
921                 ch = &part->channels[ch_number];
922
923                 if (!(ch->flags & XPC_C_WDISCONNECT)) {
924                         xpc_part_deref(part);
925                         continue;
926                 }
927
928                 wait_for_completion(&ch->wdisconnect_wait);
929
930                 spin_lock_irqsave(&ch->lock, irq_flags);
931                 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
932                 wakeup_channel_mgr = 0;
933
934                 if (ch->delayed_chctl_flags) {
935                         if (part->act_state != XPC_P_AS_DEACTIVATING) {
936                                 spin_lock(&part->chctl_lock);
937                                 part->chctl.flags[ch->number] |=
938                                     ch->delayed_chctl_flags;
939                                 spin_unlock(&part->chctl_lock);
940                                 wakeup_channel_mgr = 1;
941                         }
942                         ch->delayed_chctl_flags = 0;
943                 }
944
945                 ch->flags &= ~XPC_C_WDISCONNECT;
946                 spin_unlock_irqrestore(&ch->lock, irq_flags);
947
948                 if (wakeup_channel_mgr)
949                         xpc_wakeup_channel_mgr(part);
950
951                 xpc_part_deref(part);
952         }
953 }
954
955 static int
956 xpc_setup_partitions(void)
957 {
958         short partid;
959         struct xpc_partition *part;
960
961         xpc_partitions = kzalloc(sizeof(struct xpc_partition) *
962                                  xp_max_npartitions, GFP_KERNEL);
963         if (xpc_partitions == NULL) {
964                 dev_err(xpc_part, "can't get memory for partition structure\n");
965                 return -ENOMEM;
966         }
967
968         /*
969          * The first few fields of each entry of xpc_partitions[] need to
970          * be initialized now so that calls to xpc_connect() and
971          * xpc_disconnect() can be made prior to the activation of any remote
972          * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
973          * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
974          * PARTITION HAS BEEN ACTIVATED.
975          */
976         for (partid = 0; partid < xp_max_npartitions; partid++) {
977                 part = &xpc_partitions[partid];
978
979                 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
980
981                 part->activate_IRQ_rcvd = 0;
982                 spin_lock_init(&part->act_lock);
983                 part->act_state = XPC_P_AS_INACTIVE;
984                 XPC_SET_REASON(part, 0, 0);
985
986                 init_timer(&part->disengage_timer);
987                 part->disengage_timer.function =
988                     xpc_timeout_partition_disengage;
989                 part->disengage_timer.data = (unsigned long)part;
990
991                 part->setup_state = XPC_P_SS_UNSET;
992                 init_waitqueue_head(&part->teardown_wq);
993                 atomic_set(&part->references, 0);
994         }
995
996         return xpc_setup_partitions_sn();
997 }
998
999 static void
1000 xpc_teardown_partitions(void)
1001 {
1002         xpc_teardown_partitions_sn();
1003         kfree(xpc_partitions);
1004 }
1005
1006 static void
1007 xpc_do_exit(enum xp_retval reason)
1008 {
1009         short partid;
1010         int active_part_count, printed_waiting_msg = 0;
1011         struct xpc_partition *part;
1012         unsigned long printmsg_time, disengage_timeout = 0;
1013
1014         /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
1015         DBUG_ON(xpc_exiting == 1);
1016
1017         /*
1018          * Let the heartbeat checker thread and the discovery thread
1019          * (if one is running) know that they should exit. Also wake up
1020          * the heartbeat checker thread in case it's sleeping.
1021          */
1022         xpc_exiting = 1;
1023         wake_up_interruptible(&xpc_activate_IRQ_wq);
1024
1025         /* wait for the discovery thread to exit */
1026         wait_for_completion(&xpc_discovery_exited);
1027
1028         /* wait for the heartbeat checker thread to exit */
1029         wait_for_completion(&xpc_hb_checker_exited);
1030
1031         /* sleep for a 1/3 of a second or so */
1032         (void)msleep_interruptible(300);
1033
1034         /* wait for all partitions to become inactive */
1035
1036         printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1037         xpc_disengage_timedout = 0;
1038
1039         do {
1040                 active_part_count = 0;
1041
1042                 for (partid = 0; partid < xp_max_npartitions; partid++) {
1043                         part = &xpc_partitions[partid];
1044
1045                         if (xpc_partition_disengaged(part) &&
1046                             part->act_state == XPC_P_AS_INACTIVE) {
1047                                 continue;
1048                         }
1049
1050                         active_part_count++;
1051
1052                         XPC_DEACTIVATE_PARTITION(part, reason);
1053
1054                         if (part->disengage_timeout > disengage_timeout)
1055                                 disengage_timeout = part->disengage_timeout;
1056                 }
1057
1058                 if (xpc_any_partition_engaged()) {
1059                         if (time_is_before_jiffies(printmsg_time)) {
1060                                 dev_info(xpc_part, "waiting for remote "
1061                                          "partitions to deactivate, timeout in "
1062                                          "%ld seconds\n", (disengage_timeout -
1063                                          jiffies) / HZ);
1064                                 printmsg_time = jiffies +
1065                                     (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1066                                 printed_waiting_msg = 1;
1067                         }
1068
1069                 } else if (active_part_count > 0) {
1070                         if (printed_waiting_msg) {
1071                                 dev_info(xpc_part, "waiting for local partition"
1072                                          " to deactivate\n");
1073                                 printed_waiting_msg = 0;
1074                         }
1075
1076                 } else {
1077                         if (!xpc_disengage_timedout) {
1078                                 dev_info(xpc_part, "all partitions have "
1079                                          "deactivated\n");
1080                         }
1081                         break;
1082                 }
1083
1084                 /* sleep for a 1/3 of a second or so */
1085                 (void)msleep_interruptible(300);
1086
1087         } while (1);
1088
1089         DBUG_ON(xpc_any_partition_engaged());
1090         DBUG_ON(xpc_any_hbs_allowed() != 0);
1091
1092         xpc_teardown_rsvd_page();
1093
1094         if (reason == xpUnloading) {
1095                 (void)unregister_die_notifier(&xpc_die_notifier);
1096                 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1097         }
1098
1099         /* clear the interface to XPC's functions */
1100         xpc_clear_interface();
1101
1102         if (xpc_sysctl)
1103                 unregister_sysctl_table(xpc_sysctl);
1104
1105         xpc_teardown_partitions();
1106
1107         if (is_shub())
1108                 xpc_exit_sn2();
1109         else if (is_uv())
1110                 xpc_exit_uv();
1111 }
1112
1113 /*
1114  * This function is called when the system is being rebooted.
1115  */
1116 static int
1117 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1118 {
1119         enum xp_retval reason;
1120
1121         switch (event) {
1122         case SYS_RESTART:
1123                 reason = xpSystemReboot;
1124                 break;
1125         case SYS_HALT:
1126                 reason = xpSystemHalt;
1127                 break;
1128         case SYS_POWER_OFF:
1129                 reason = xpSystemPoweroff;
1130                 break;
1131         default:
1132                 reason = xpSystemGoingDown;
1133         }
1134
1135         xpc_do_exit(reason);
1136         return NOTIFY_DONE;
1137 }
1138
1139 /*
1140  * Notify other partitions to deactivate from us by first disengaging from all
1141  * references to our memory.
1142  */
1143 static void
1144 xpc_die_deactivate(void)
1145 {
1146         struct xpc_partition *part;
1147         short partid;
1148         int any_engaged;
1149         long keep_waiting;
1150         long wait_to_print;
1151
1152         /* keep xpc_hb_checker thread from doing anything (just in case) */
1153         xpc_exiting = 1;
1154
1155         xpc_disallow_all_hbs(); /*indicate we're deactivated */
1156
1157         for (partid = 0; partid < xp_max_npartitions; partid++) {
1158                 part = &xpc_partitions[partid];
1159
1160                 if (xpc_partition_engaged(partid) ||
1161                     part->act_state != XPC_P_AS_INACTIVE) {
1162                         xpc_request_partition_deactivation(part);
1163                         xpc_indicate_partition_disengaged(part);
1164                 }
1165         }
1166
1167         /*
1168          * Though we requested that all other partitions deactivate from us,
1169          * we only wait until they've all disengaged or we've reached the
1170          * defined timelimit.
1171          *
1172          * Given that one iteration through the following while-loop takes
1173          * approximately 200 microseconds, calculate the #of loops to take
1174          * before bailing and the #of loops before printing a waiting message.
1175          */
1176         keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1177         wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1178
1179         while (1) {
1180                 any_engaged = xpc_any_partition_engaged();
1181                 if (!any_engaged) {
1182                         dev_info(xpc_part, "all partitions have deactivated\n");
1183                         break;
1184                 }
1185
1186                 if (!keep_waiting--) {
1187                         for (partid = 0; partid < xp_max_npartitions;
1188                              partid++) {
1189                                 if (xpc_partition_engaged(partid)) {
1190                                         dev_info(xpc_part, "deactivate from "
1191                                                  "remote partition %d timed "
1192                                                  "out\n", partid);
1193                                 }
1194                         }
1195                         break;
1196                 }
1197
1198                 if (!wait_to_print--) {
1199                         dev_info(xpc_part, "waiting for remote partitions to "
1200                                  "deactivate, timeout in %ld seconds\n",
1201                                  keep_waiting / (1000 * 5));
1202                         wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1203                             1000 * 5;
1204                 }
1205
1206                 udelay(200);
1207         }
1208 }
1209
1210 /*
1211  * This function is called when the system is being restarted or halted due
1212  * to some sort of system failure. If this is the case we need to notify the
1213  * other partitions to disengage from all references to our memory.
1214  * This function can also be called when our heartbeater could be offlined
1215  * for a time. In this case we need to notify other partitions to not worry
1216  * about the lack of a heartbeat.
1217  */
1218 static int
1219 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1220 {
1221 #ifdef CONFIG_IA64              /* !!! temporary kludge */
1222         switch (event) {
1223         case DIE_MACHINE_RESTART:
1224         case DIE_MACHINE_HALT:
1225                 xpc_die_deactivate();
1226                 break;
1227
1228         case DIE_KDEBUG_ENTER:
1229                 /* Should lack of heartbeat be ignored by other partitions? */
1230                 if (!xpc_kdebug_ignore)
1231                         break;
1232
1233                 /* fall through */
1234         case DIE_MCA_MONARCH_ENTER:
1235         case DIE_INIT_MONARCH_ENTER:
1236                 xpc_offline_heartbeat();
1237                 break;
1238
1239         case DIE_KDEBUG_LEAVE:
1240                 /* Is lack of heartbeat being ignored by other partitions? */
1241                 if (!xpc_kdebug_ignore)
1242                         break;
1243
1244                 /* fall through */
1245         case DIE_MCA_MONARCH_LEAVE:
1246         case DIE_INIT_MONARCH_LEAVE:
1247                 xpc_online_heartbeat();
1248                 break;
1249         }
1250 #else
1251         xpc_die_deactivate();
1252 #endif
1253
1254         return NOTIFY_DONE;
1255 }
1256
1257 int __init
1258 xpc_init(void)
1259 {
1260         int ret;
1261         struct task_struct *kthread;
1262
1263         dev_set_name(xpc_part, "part");
1264         dev_set_name(xpc_chan, "chan");
1265
1266         if (is_shub()) {
1267                 /*
1268                  * The ia64-sn2 architecture supports at most 64 partitions.
1269                  * And the inability to unregister remote amos restricts us
1270                  * further to only support exactly 64 partitions on this
1271                  * architecture, no less.
1272                  */
1273                 if (xp_max_npartitions != 64) {
1274                         dev_err(xpc_part, "max #of partitions not set to 64\n");
1275                         ret = -EINVAL;
1276                 } else {
1277                         ret = xpc_init_sn2();
1278                 }
1279
1280         } else if (is_uv()) {
1281                 ret = xpc_init_uv();
1282
1283         } else {
1284                 ret = -ENODEV;
1285         }
1286
1287         if (ret != 0)
1288                 return ret;
1289
1290         ret = xpc_setup_partitions();
1291         if (ret != 0) {
1292                 dev_err(xpc_part, "can't get memory for partition structure\n");
1293                 goto out_1;
1294         }
1295
1296         xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1297
1298         /*
1299          * Fill the partition reserved page with the information needed by
1300          * other partitions to discover we are alive and establish initial
1301          * communications.
1302          */
1303         ret = xpc_setup_rsvd_page();
1304         if (ret != 0) {
1305                 dev_err(xpc_part, "can't setup our reserved page\n");
1306                 goto out_2;
1307         }
1308
1309         /* add ourselves to the reboot_notifier_list */
1310         ret = register_reboot_notifier(&xpc_reboot_notifier);
1311         if (ret != 0)
1312                 dev_warn(xpc_part, "can't register reboot notifier\n");
1313
1314         /* add ourselves to the die_notifier list */
1315         ret = register_die_notifier(&xpc_die_notifier);
1316         if (ret != 0)
1317                 dev_warn(xpc_part, "can't register die notifier\n");
1318
1319         /*
1320          * The real work-horse behind xpc.  This processes incoming
1321          * interrupts and monitors remote heartbeats.
1322          */
1323         kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1324         if (IS_ERR(kthread)) {
1325                 dev_err(xpc_part, "failed while forking hb check thread\n");
1326                 ret = -EBUSY;
1327                 goto out_3;
1328         }
1329
1330         /*
1331          * Startup a thread that will attempt to discover other partitions to
1332          * activate based on info provided by SAL. This new thread is short
1333          * lived and will exit once discovery is complete.
1334          */
1335         kthread = kthread_run(xpc_initiate_discovery, NULL,
1336                               XPC_DISCOVERY_THREAD_NAME);
1337         if (IS_ERR(kthread)) {
1338                 dev_err(xpc_part, "failed while forking discovery thread\n");
1339
1340                 /* mark this new thread as a non-starter */
1341                 complete(&xpc_discovery_exited);
1342
1343                 xpc_do_exit(xpUnloading);
1344                 return -EBUSY;
1345         }
1346
1347         /* set the interface to point at XPC's functions */
1348         xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1349                           xpc_initiate_send, xpc_initiate_send_notify,
1350                           xpc_initiate_received, xpc_initiate_partid_to_nasids);
1351
1352         return 0;
1353
1354         /* initialization was not successful */
1355 out_3:
1356         xpc_teardown_rsvd_page();
1357
1358         (void)unregister_die_notifier(&xpc_die_notifier);
1359         (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1360 out_2:
1361         if (xpc_sysctl)
1362                 unregister_sysctl_table(xpc_sysctl);
1363
1364         xpc_teardown_partitions();
1365 out_1:
1366         if (is_shub())
1367                 xpc_exit_sn2();
1368         else if (is_uv())
1369                 xpc_exit_uv();
1370         return ret;
1371 }
1372
1373 module_init(xpc_init);
1374
1375 void __exit
1376 xpc_exit(void)
1377 {
1378         xpc_do_exit(xpUnloading);
1379 }
1380
1381 module_exit(xpc_exit);
1382
1383 MODULE_AUTHOR("Silicon Graphics, Inc.");
1384 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1385 MODULE_LICENSE("GPL");
1386
1387 module_param(xpc_hb_interval, int, 0);
1388 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1389                  "heartbeat increments.");
1390
1391 module_param(xpc_hb_check_interval, int, 0);
1392 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1393                  "heartbeat checks.");
1394
1395 module_param(xpc_disengage_timelimit, int, 0);
1396 MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1397                  "for disengage to complete.");
1398
1399 module_param(xpc_kdebug_ignore, int, 0);
1400 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1401                  "other partitions when dropping into kdebug.");