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