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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 /* check for outstanding IRQs */
285 if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
286 force_IRQ = 0;
287 dev_dbg(xpc_part, "processing activate IRQs "
288 "received\n");
289 xpc_arch_ops.process_activate_IRQ_rcvd();
290 }
291
292 /* wait for IRQ or timeout */
293 (void)wait_event_interruptible(xpc_activate_IRQ_wq,
294 (time_is_before_eq_jiffies(
295 xpc_hb_check_timeout) ||
296 xpc_activate_IRQ_rcvd > 0 ||
297 xpc_exiting));
298 }
299
300 xpc_stop_hb_beater();
301
302 dev_dbg(xpc_part, "heartbeat checker is exiting\n");
303
304 /* mark this thread as having exited */
305 complete(&xpc_hb_checker_exited);
306 return 0;
307}
308
309/*
310 * This thread will attempt to discover other partitions to activate
311 * based on info provided by SAL. This new thread is short lived and
312 * will exit once discovery is complete.
313 */
314static int
315xpc_initiate_discovery(void *ignore)
316{
317 xpc_discovery();
318
319 dev_dbg(xpc_part, "discovery thread is exiting\n");
320
321 /* mark this thread as having exited */
322 complete(&xpc_discovery_exited);
323 return 0;
324}
325
326/*
327 * The first kthread assigned to a newly activated partition is the one
328 * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
329 * that kthread until the partition is brought down, at which time that kthread
330 * returns back to XPC HB. (The return of that kthread will signify to XPC HB
331 * that XPC has dismantled all communication infrastructure for the associated
332 * partition.) This kthread becomes the channel manager for that partition.
333 *
334 * Each active partition has a channel manager, who, besides connecting and
335 * disconnecting channels, will ensure that each of the partition's connected
336 * channels has the required number of assigned kthreads to get the work done.
337 */
338static void
339xpc_channel_mgr(struct xpc_partition *part)
340{
341 while (part->act_state != XPC_P_AS_DEACTIVATING ||
342 atomic_read(&part->nchannels_active) > 0 ||
343 !xpc_partition_disengaged(part)) {
344
345 xpc_process_sent_chctl_flags(part);
346
347 /*
348 * Wait until we've been requested to activate kthreads or
349 * all of the channel's message queues have been torn down or
350 * a signal is pending.
351 *
352 * The channel_mgr_requests is set to 1 after being awakened,
353 * This is done to prevent the channel mgr from making one pass
354 * through the loop for each request, since he will
355 * be servicing all the requests in one pass. The reason it's
356 * set to 1 instead of 0 is so that other kthreads will know
357 * that the channel mgr is running and won't bother trying to
358 * wake him up.
359 */
360 atomic_dec(&part->channel_mgr_requests);
361 (void)wait_event_interruptible(part->channel_mgr_wq,
362 (atomic_read(&part->channel_mgr_requests) > 0 ||
363 part->chctl.all_flags != 0 ||
364 (part->act_state == XPC_P_AS_DEACTIVATING &&
365 atomic_read(&part->nchannels_active) == 0 &&
366 xpc_partition_disengaged(part))));
367 atomic_set(&part->channel_mgr_requests, 1);
368 }
369}
370
371/*
372 * Guarantee that the kzalloc'd memory is cacheline aligned.
373 */
374void *
375xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
376{
377 /* see if kzalloc will give us cachline aligned memory by default */
378 *base = kzalloc(size, flags);
379 if (*base == NULL)
380 return NULL;
381
382 if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
383 return *base;
384
385 kfree(*base);
386
387 /* nope, we'll have to do it ourselves */
388 *base = kzalloc(size + L1_CACHE_BYTES, flags);
389 if (*base == NULL)
390 return NULL;
391
392 return (void *)L1_CACHE_ALIGN((u64)*base);
393}
394
395/*
396 * Setup the channel structures necessary to support XPartition Communication
397 * between the specified remote partition and the local one.
398 */
399static enum xp_retval
400xpc_setup_ch_structures(struct xpc_partition *part)
401{
402 enum xp_retval ret;
403 int ch_number;
404 struct xpc_channel *ch;
405 short partid = XPC_PARTID(part);
406
407 /*
408 * Allocate all of the channel structures as a contiguous chunk of
409 * memory.
410 */
411 DBUG_ON(part->channels != NULL);
412 part->channels = kcalloc(XPC_MAX_NCHANNELS,
413 sizeof(struct xpc_channel),
414 GFP_KERNEL);
415 if (part->channels == NULL) {
416 dev_err(xpc_chan, "can't get memory for channels\n");
417 return xpNoMemory;
418 }
419
420 /* allocate the remote open and close args */
421
422 part->remote_openclose_args =
423 xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
424 GFP_KERNEL, &part->
425 remote_openclose_args_base);
426 if (part->remote_openclose_args == NULL) {
427 dev_err(xpc_chan, "can't get memory for remote connect args\n");
428 ret = xpNoMemory;
429 goto out_1;
430 }
431
432 part->chctl.all_flags = 0;
433 spin_lock_init(&part->chctl_lock);
434
435 atomic_set(&part->channel_mgr_requests, 1);
436 init_waitqueue_head(&part->channel_mgr_wq);
437
438 part->nchannels = XPC_MAX_NCHANNELS;
439
440 atomic_set(&part->nchannels_active, 0);
441 atomic_set(&part->nchannels_engaged, 0);
442
443 for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
444 ch = &part->channels[ch_number];
445
446 ch->partid = partid;
447 ch->number = ch_number;
448 ch->flags = XPC_C_DISCONNECTED;
449
450 atomic_set(&ch->kthreads_assigned, 0);
451 atomic_set(&ch->kthreads_idle, 0);
452 atomic_set(&ch->kthreads_active, 0);
453
454 atomic_set(&ch->references, 0);
455 atomic_set(&ch->n_to_notify, 0);
456
457 spin_lock_init(&ch->lock);
458 init_completion(&ch->wdisconnect_wait);
459
460 atomic_set(&ch->n_on_msg_allocate_wq, 0);
461 init_waitqueue_head(&ch->msg_allocate_wq);
462 init_waitqueue_head(&ch->idle_wq);
463 }
464
465 ret = xpc_arch_ops.setup_ch_structures(part);
466 if (ret != xpSuccess)
467 goto out_2;
468
469 /*
470 * With the setting of the partition setup_state to XPC_P_SS_SETUP,
471 * we're declaring that this partition is ready to go.
472 */
473 part->setup_state = XPC_P_SS_SETUP;
474
475 return xpSuccess;
476
477 /* setup of ch structures failed */
478out_2:
479 kfree(part->remote_openclose_args_base);
480 part->remote_openclose_args = NULL;
481out_1:
482 kfree(part->channels);
483 part->channels = NULL;
484 return ret;
485}
486
487/*
488 * Teardown the channel structures necessary to support XPartition Communication
489 * between the specified remote partition and the local one.
490 */
491static void
492xpc_teardown_ch_structures(struct xpc_partition *part)
493{
494 DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
495 DBUG_ON(atomic_read(&part->nchannels_active) != 0);
496
497 /*
498 * Make this partition inaccessible to local processes by marking it
499 * as no longer setup. Then wait before proceeding with the teardown
500 * until all existing references cease.
501 */
502 DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
503 part->setup_state = XPC_P_SS_WTEARDOWN;
504
505 wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
506
507 /* now we can begin tearing down the infrastructure */
508
509 xpc_arch_ops.teardown_ch_structures(part);
510
511 kfree(part->remote_openclose_args_base);
512 part->remote_openclose_args = NULL;
513 kfree(part->channels);
514 part->channels = NULL;
515
516 part->setup_state = XPC_P_SS_TORNDOWN;
517}
518
519/*
520 * When XPC HB determines that a partition has come up, it will create a new
521 * kthread and that kthread will call this function to attempt to set up the
522 * basic infrastructure used for Cross Partition Communication with the newly
523 * upped partition.
524 *
525 * The kthread that was created by XPC HB and which setup the XPC
526 * infrastructure will remain assigned to the partition becoming the channel
527 * manager for that partition until the partition is deactivating, at which
528 * time the kthread will teardown the XPC infrastructure and then exit.
529 */
530static int
531xpc_activating(void *__partid)
532{
533 short partid = (u64)__partid;
534 struct xpc_partition *part = &xpc_partitions[partid];
535 unsigned long irq_flags;
536
537 DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
538
539 spin_lock_irqsave(&part->act_lock, irq_flags);
540
541 if (part->act_state == XPC_P_AS_DEACTIVATING) {
542 part->act_state = XPC_P_AS_INACTIVE;
543 spin_unlock_irqrestore(&part->act_lock, irq_flags);
544 part->remote_rp_pa = 0;
545 return 0;
546 }
547
548 /* indicate the thread is activating */
549 DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
550 part->act_state = XPC_P_AS_ACTIVATING;
551
552 XPC_SET_REASON(part, 0, 0);
553 spin_unlock_irqrestore(&part->act_lock, irq_flags);
554
555 dev_dbg(xpc_part, "activating partition %d\n", partid);
556
557 xpc_arch_ops.allow_hb(partid);
558
559 if (xpc_setup_ch_structures(part) == xpSuccess) {
560 (void)xpc_part_ref(part); /* this will always succeed */
561
562 if (xpc_arch_ops.make_first_contact(part) == xpSuccess) {
563 xpc_mark_partition_active(part);
564 xpc_channel_mgr(part);
565 /* won't return until partition is deactivating */
566 }
567
568 xpc_part_deref(part);
569 xpc_teardown_ch_structures(part);
570 }
571
572 xpc_arch_ops.disallow_hb(partid);
573 xpc_mark_partition_inactive(part);
574
575 if (part->reason == xpReactivating) {
576 /* interrupting ourselves results in activating partition */
577 xpc_arch_ops.request_partition_reactivation(part);
578 }
579
580 return 0;
581}
582
583void
584xpc_activate_partition(struct xpc_partition *part)
585{
586 short partid = XPC_PARTID(part);
587 unsigned long irq_flags;
588 struct task_struct *kthread;
589
590 spin_lock_irqsave(&part->act_lock, irq_flags);
591
592 DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
593
594 part->act_state = XPC_P_AS_ACTIVATION_REQ;
595 XPC_SET_REASON(part, xpCloneKThread, __LINE__);
596
597 spin_unlock_irqrestore(&part->act_lock, irq_flags);
598
599 kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
600 partid);
601 if (IS_ERR(kthread)) {
602 spin_lock_irqsave(&part->act_lock, irq_flags);
603 part->act_state = XPC_P_AS_INACTIVE;
604 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
605 spin_unlock_irqrestore(&part->act_lock, irq_flags);
606 }
607}
608
609void
610xpc_activate_kthreads(struct xpc_channel *ch, int needed)
611{
612 int idle = atomic_read(&ch->kthreads_idle);
613 int assigned = atomic_read(&ch->kthreads_assigned);
614 int wakeup;
615
616 DBUG_ON(needed <= 0);
617
618 if (idle > 0) {
619 wakeup = (needed > idle) ? idle : needed;
620 needed -= wakeup;
621
622 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
623 "channel=%d\n", wakeup, ch->partid, ch->number);
624
625 /* only wakeup the requested number of kthreads */
626 wake_up_nr(&ch->idle_wq, wakeup);
627 }
628
629 if (needed <= 0)
630 return;
631
632 if (needed + assigned > ch->kthreads_assigned_limit) {
633 needed = ch->kthreads_assigned_limit - assigned;
634 if (needed <= 0)
635 return;
636 }
637
638 dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
639 needed, ch->partid, ch->number);
640
641 xpc_create_kthreads(ch, needed, 0);
642}
643
644/*
645 * This function is where XPC's kthreads wait for messages to deliver.
646 */
647static void
648xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
649{
650 int (*n_of_deliverable_payloads) (struct xpc_channel *) =
651 xpc_arch_ops.n_of_deliverable_payloads;
652
653 do {
654 /* deliver messages to their intended recipients */
655
656 while (n_of_deliverable_payloads(ch) > 0 &&
657 !(ch->flags & XPC_C_DISCONNECTING)) {
658 xpc_deliver_payload(ch);
659 }
660
661 if (atomic_inc_return(&ch->kthreads_idle) >
662 ch->kthreads_idle_limit) {
663 /* too many idle kthreads on this channel */
664 atomic_dec(&ch->kthreads_idle);
665 break;
666 }
667
668 dev_dbg(xpc_chan, "idle kthread calling "
669 "wait_event_interruptible_exclusive()\n");
670
671 (void)wait_event_interruptible_exclusive(ch->idle_wq,
672 (n_of_deliverable_payloads(ch) > 0 ||
673 (ch->flags & XPC_C_DISCONNECTING)));
674
675 atomic_dec(&ch->kthreads_idle);
676
677 } while (!(ch->flags & XPC_C_DISCONNECTING));
678}
679
680static int
681xpc_kthread_start(void *args)
682{
683 short partid = XPC_UNPACK_ARG1(args);
684 u16 ch_number = XPC_UNPACK_ARG2(args);
685 struct xpc_partition *part = &xpc_partitions[partid];
686 struct xpc_channel *ch;
687 int n_needed;
688 unsigned long irq_flags;
689 int (*n_of_deliverable_payloads) (struct xpc_channel *) =
690 xpc_arch_ops.n_of_deliverable_payloads;
691
692 dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
693 partid, ch_number);
694
695 ch = &part->channels[ch_number];
696
697 if (!(ch->flags & XPC_C_DISCONNECTING)) {
698
699 /* let registerer know that connection has been established */
700
701 spin_lock_irqsave(&ch->lock, irq_flags);
702 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
703 ch->flags |= XPC_C_CONNECTEDCALLOUT;
704 spin_unlock_irqrestore(&ch->lock, irq_flags);
705
706 xpc_connected_callout(ch);
707
708 spin_lock_irqsave(&ch->lock, irq_flags);
709 ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
710 spin_unlock_irqrestore(&ch->lock, irq_flags);
711
712 /*
713 * It is possible that while the callout was being
714 * made that the remote partition sent some messages.
715 * If that is the case, we may need to activate
716 * additional kthreads to help deliver them. We only
717 * need one less than total #of messages to deliver.
718 */
719 n_needed = n_of_deliverable_payloads(ch) - 1;
720 if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
721 xpc_activate_kthreads(ch, n_needed);
722
723 } else {
724 spin_unlock_irqrestore(&ch->lock, irq_flags);
725 }
726
727 xpc_kthread_waitmsgs(part, ch);
728 }
729
730 /* let registerer know that connection is disconnecting */
731
732 spin_lock_irqsave(&ch->lock, irq_flags);
733 if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
734 !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
735 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
736 spin_unlock_irqrestore(&ch->lock, irq_flags);
737
738 xpc_disconnect_callout(ch, xpDisconnecting);
739
740 spin_lock_irqsave(&ch->lock, irq_flags);
741 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
742 }
743 spin_unlock_irqrestore(&ch->lock, irq_flags);
744
745 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
746 atomic_dec_return(&part->nchannels_engaged) == 0) {
747 xpc_arch_ops.indicate_partition_disengaged(part);
748 }
749
750 xpc_msgqueue_deref(ch);
751
752 dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
753 partid, ch_number);
754
755 xpc_part_deref(part);
756 return 0;
757}
758
759/*
760 * For each partition that XPC has established communications with, there is
761 * a minimum of one kernel thread assigned to perform any operation that
762 * may potentially sleep or block (basically the callouts to the asynchronous
763 * functions registered via xpc_connect()).
764 *
765 * Additional kthreads are created and destroyed by XPC as the workload
766 * demands.
767 *
768 * A kthread is assigned to one of the active channels that exists for a given
769 * partition.
770 */
771void
772xpc_create_kthreads(struct xpc_channel *ch, int needed,
773 int ignore_disconnecting)
774{
775 unsigned long irq_flags;
776 u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
777 struct xpc_partition *part = &xpc_partitions[ch->partid];
778 struct task_struct *kthread;
779 void (*indicate_partition_disengaged) (struct xpc_partition *) =
780 xpc_arch_ops.indicate_partition_disengaged;
781
782 while (needed-- > 0) {
783
784 /*
785 * The following is done on behalf of the newly created
786 * kthread. That kthread is responsible for doing the
787 * counterpart to the following before it exits.
788 */
789 if (ignore_disconnecting) {
790 if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
791 /* kthreads assigned had gone to zero */
792 BUG_ON(!(ch->flags &
793 XPC_C_DISCONNECTINGCALLOUT_MADE));
794 break;
795 }
796
797 } else if (ch->flags & XPC_C_DISCONNECTING) {
798 break;
799
800 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
801 atomic_inc_return(&part->nchannels_engaged) == 1) {
802 xpc_arch_ops.indicate_partition_engaged(part);
803 }
804 (void)xpc_part_ref(part);
805 xpc_msgqueue_ref(ch);
806
807 kthread = kthread_run(xpc_kthread_start, (void *)args,
808 "xpc%02dc%d", ch->partid, ch->number);
809 if (IS_ERR(kthread)) {
810 /* the fork failed */
811
812 /*
813 * NOTE: if (ignore_disconnecting &&
814 * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
815 * then we'll deadlock if all other kthreads assigned
816 * to this channel are blocked in the channel's
817 * registerer, because the only thing that will unblock
818 * them is the xpDisconnecting callout that this
819 * failed kthread_run() would have made.
820 */
821
822 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
823 atomic_dec_return(&part->nchannels_engaged) == 0) {
824 indicate_partition_disengaged(part);
825 }
826 xpc_msgqueue_deref(ch);
827 xpc_part_deref(part);
828
829 if (atomic_read(&ch->kthreads_assigned) <
830 ch->kthreads_idle_limit) {
831 /*
832 * Flag this as an error only if we have an
833 * insufficient #of kthreads for the channel
834 * to function.
835 */
836 spin_lock_irqsave(&ch->lock, irq_flags);
837 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
838 &irq_flags);
839 spin_unlock_irqrestore(&ch->lock, irq_flags);
840 }
841 break;
842 }
843 }
844}
845
846void
847xpc_disconnect_wait(int ch_number)
848{
849 unsigned long irq_flags;
850 short partid;
851 struct xpc_partition *part;
852 struct xpc_channel *ch;
853 int wakeup_channel_mgr;
854
855 /* now wait for all callouts to the caller's function to cease */
856 for (partid = 0; partid < xp_max_npartitions; partid++) {
857 part = &xpc_partitions[partid];
858
859 if (!xpc_part_ref(part))
860 continue;
861
862 ch = &part->channels[ch_number];
863
864 if (!(ch->flags & XPC_C_WDISCONNECT)) {
865 xpc_part_deref(part);
866 continue;
867 }
868
869 wait_for_completion(&ch->wdisconnect_wait);
870
871 spin_lock_irqsave(&ch->lock, irq_flags);
872 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
873 wakeup_channel_mgr = 0;
874
875 if (ch->delayed_chctl_flags) {
876 if (part->act_state != XPC_P_AS_DEACTIVATING) {
877 spin_lock(&part->chctl_lock);
878 part->chctl.flags[ch->number] |=
879 ch->delayed_chctl_flags;
880 spin_unlock(&part->chctl_lock);
881 wakeup_channel_mgr = 1;
882 }
883 ch->delayed_chctl_flags = 0;
884 }
885
886 ch->flags &= ~XPC_C_WDISCONNECT;
887 spin_unlock_irqrestore(&ch->lock, irq_flags);
888
889 if (wakeup_channel_mgr)
890 xpc_wakeup_channel_mgr(part);
891
892 xpc_part_deref(part);
893 }
894}
895
896static int
897xpc_setup_partitions(void)
898{
899 short partid;
900 struct xpc_partition *part;
901
902 xpc_partitions = kcalloc(xp_max_npartitions,
903 sizeof(struct xpc_partition),
904 GFP_KERNEL);
905 if (xpc_partitions == NULL) {
906 dev_err(xpc_part, "can't get memory for partition structure\n");
907 return -ENOMEM;
908 }
909
910 /*
911 * The first few fields of each entry of xpc_partitions[] need to
912 * be initialized now so that calls to xpc_connect() and
913 * xpc_disconnect() can be made prior to the activation of any remote
914 * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
915 * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
916 * PARTITION HAS BEEN ACTIVATED.
917 */
918 for (partid = 0; partid < xp_max_npartitions; partid++) {
919 part = &xpc_partitions[partid];
920
921 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
922
923 part->activate_IRQ_rcvd = 0;
924 spin_lock_init(&part->act_lock);
925 part->act_state = XPC_P_AS_INACTIVE;
926 XPC_SET_REASON(part, 0, 0);
927
928 timer_setup(&part->disengage_timer,
929 xpc_timeout_partition_disengage, 0);
930
931 part->setup_state = XPC_P_SS_UNSET;
932 init_waitqueue_head(&part->teardown_wq);
933 atomic_set(&part->references, 0);
934 }
935
936 return xpc_arch_ops.setup_partitions();
937}
938
939static void
940xpc_teardown_partitions(void)
941{
942 xpc_arch_ops.teardown_partitions();
943 kfree(xpc_partitions);
944}
945
946static void
947xpc_do_exit(enum xp_retval reason)
948{
949 short partid;
950 int active_part_count, printed_waiting_msg = 0;
951 struct xpc_partition *part;
952 unsigned long printmsg_time, disengage_timeout = 0;
953
954 /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
955 DBUG_ON(xpc_exiting == 1);
956
957 /*
958 * Let the heartbeat checker thread and the discovery thread
959 * (if one is running) know that they should exit. Also wake up
960 * the heartbeat checker thread in case it's sleeping.
961 */
962 xpc_exiting = 1;
963 wake_up_interruptible(&xpc_activate_IRQ_wq);
964
965 /* wait for the discovery thread to exit */
966 wait_for_completion(&xpc_discovery_exited);
967
968 /* wait for the heartbeat checker thread to exit */
969 wait_for_completion(&xpc_hb_checker_exited);
970
971 /* sleep for a 1/3 of a second or so */
972 (void)msleep_interruptible(300);
973
974 /* wait for all partitions to become inactive */
975
976 printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
977 xpc_disengage_timedout = 0;
978
979 do {
980 active_part_count = 0;
981
982 for (partid = 0; partid < xp_max_npartitions; partid++) {
983 part = &xpc_partitions[partid];
984
985 if (xpc_partition_disengaged(part) &&
986 part->act_state == XPC_P_AS_INACTIVE) {
987 continue;
988 }
989
990 active_part_count++;
991
992 XPC_DEACTIVATE_PARTITION(part, reason);
993
994 if (part->disengage_timeout > disengage_timeout)
995 disengage_timeout = part->disengage_timeout;
996 }
997
998 if (xpc_arch_ops.any_partition_engaged()) {
999 if (time_is_before_jiffies(printmsg_time)) {
1000 dev_info(xpc_part, "waiting for remote "
1001 "partitions to deactivate, timeout in "
1002 "%ld seconds\n", (disengage_timeout -
1003 jiffies) / HZ);
1004 printmsg_time = jiffies +
1005 (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1006 printed_waiting_msg = 1;
1007 }
1008
1009 } else if (active_part_count > 0) {
1010 if (printed_waiting_msg) {
1011 dev_info(xpc_part, "waiting for local partition"
1012 " to deactivate\n");
1013 printed_waiting_msg = 0;
1014 }
1015
1016 } else {
1017 if (!xpc_disengage_timedout) {
1018 dev_info(xpc_part, "all partitions have "
1019 "deactivated\n");
1020 }
1021 break;
1022 }
1023
1024 /* sleep for a 1/3 of a second or so */
1025 (void)msleep_interruptible(300);
1026
1027 } while (1);
1028
1029 DBUG_ON(xpc_arch_ops.any_partition_engaged());
1030
1031 xpc_teardown_rsvd_page();
1032
1033 if (reason == xpUnloading) {
1034 (void)unregister_die_notifier(&xpc_die_notifier);
1035 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1036 }
1037
1038 /* clear the interface to XPC's functions */
1039 xpc_clear_interface();
1040
1041 if (xpc_sysctl)
1042 unregister_sysctl_table(xpc_sysctl);
1043
1044 xpc_teardown_partitions();
1045
1046 if (is_uv())
1047 xpc_exit_uv();
1048}
1049
1050/*
1051 * This function is called when the system is being rebooted.
1052 */
1053static int
1054xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1055{
1056 enum xp_retval reason;
1057
1058 switch (event) {
1059 case SYS_RESTART:
1060 reason = xpSystemReboot;
1061 break;
1062 case SYS_HALT:
1063 reason = xpSystemHalt;
1064 break;
1065 case SYS_POWER_OFF:
1066 reason = xpSystemPoweroff;
1067 break;
1068 default:
1069 reason = xpSystemGoingDown;
1070 }
1071
1072 xpc_do_exit(reason);
1073 return NOTIFY_DONE;
1074}
1075
1076/* Used to only allow one cpu to complete disconnect */
1077static unsigned int xpc_die_disconnecting;
1078
1079/*
1080 * Notify other partitions to deactivate from us by first disengaging from all
1081 * references to our memory.
1082 */
1083static void
1084xpc_die_deactivate(void)
1085{
1086 struct xpc_partition *part;
1087 short partid;
1088 int any_engaged;
1089 long keep_waiting;
1090 long wait_to_print;
1091
1092 if (cmpxchg(&xpc_die_disconnecting, 0, 1))
1093 return;
1094
1095 /* keep xpc_hb_checker thread from doing anything (just in case) */
1096 xpc_exiting = 1;
1097
1098 xpc_arch_ops.disallow_all_hbs(); /*indicate we're deactivated */
1099
1100 for (partid = 0; partid < xp_max_npartitions; partid++) {
1101 part = &xpc_partitions[partid];
1102
1103 if (xpc_arch_ops.partition_engaged(partid) ||
1104 part->act_state != XPC_P_AS_INACTIVE) {
1105 xpc_arch_ops.request_partition_deactivation(part);
1106 xpc_arch_ops.indicate_partition_disengaged(part);
1107 }
1108 }
1109
1110 /*
1111 * Though we requested that all other partitions deactivate from us,
1112 * we only wait until they've all disengaged or we've reached the
1113 * defined timelimit.
1114 *
1115 * Given that one iteration through the following while-loop takes
1116 * approximately 200 microseconds, calculate the #of loops to take
1117 * before bailing and the #of loops before printing a waiting message.
1118 */
1119 keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1120 wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1121
1122 while (1) {
1123 any_engaged = xpc_arch_ops.any_partition_engaged();
1124 if (!any_engaged) {
1125 dev_info(xpc_part, "all partitions have deactivated\n");
1126 break;
1127 }
1128
1129 if (!keep_waiting--) {
1130 for (partid = 0; partid < xp_max_npartitions;
1131 partid++) {
1132 if (xpc_arch_ops.partition_engaged(partid)) {
1133 dev_info(xpc_part, "deactivate from "
1134 "remote partition %d timed "
1135 "out\n", partid);
1136 }
1137 }
1138 break;
1139 }
1140
1141 if (!wait_to_print--) {
1142 dev_info(xpc_part, "waiting for remote partitions to "
1143 "deactivate, timeout in %ld seconds\n",
1144 keep_waiting / (1000 * 5));
1145 wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1146 1000 * 5;
1147 }
1148
1149 udelay(200);
1150 }
1151}
1152
1153/*
1154 * This function is called when the system is being restarted or halted due
1155 * to some sort of system failure. If this is the case we need to notify the
1156 * other partitions to disengage from all references to our memory.
1157 * This function can also be called when our heartbeater could be offlined
1158 * for a time. In this case we need to notify other partitions to not worry
1159 * about the lack of a heartbeat.
1160 */
1161static int
1162xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args)
1163{
1164#ifdef CONFIG_IA64 /* !!! temporary kludge */
1165 switch (event) {
1166 case DIE_MACHINE_RESTART:
1167 case DIE_MACHINE_HALT:
1168 xpc_die_deactivate();
1169 break;
1170
1171 case DIE_KDEBUG_ENTER:
1172 /* Should lack of heartbeat be ignored by other partitions? */
1173 if (!xpc_kdebug_ignore)
1174 break;
1175
1176 /* fall through */
1177 case DIE_MCA_MONARCH_ENTER:
1178 case DIE_INIT_MONARCH_ENTER:
1179 xpc_arch_ops.offline_heartbeat();
1180 break;
1181
1182 case DIE_KDEBUG_LEAVE:
1183 /* Is lack of heartbeat being ignored by other partitions? */
1184 if (!xpc_kdebug_ignore)
1185 break;
1186
1187 /* fall through */
1188 case DIE_MCA_MONARCH_LEAVE:
1189 case DIE_INIT_MONARCH_LEAVE:
1190 xpc_arch_ops.online_heartbeat();
1191 break;
1192 }
1193#else
1194 struct die_args *die_args = _die_args;
1195
1196 switch (event) {
1197 case DIE_TRAP:
1198 if (die_args->trapnr == X86_TRAP_DF)
1199 xpc_die_deactivate();
1200
1201 if (((die_args->trapnr == X86_TRAP_MF) ||
1202 (die_args->trapnr == X86_TRAP_XF)) &&
1203 !user_mode(die_args->regs))
1204 xpc_die_deactivate();
1205
1206 break;
1207 case DIE_INT3:
1208 case DIE_DEBUG:
1209 break;
1210 case DIE_OOPS:
1211 case DIE_GPF:
1212 default:
1213 xpc_die_deactivate();
1214 }
1215#endif
1216
1217 return NOTIFY_DONE;
1218}
1219
1220int __init
1221xpc_init(void)
1222{
1223 int ret;
1224 struct task_struct *kthread;
1225
1226 dev_set_name(xpc_part, "part");
1227 dev_set_name(xpc_chan, "chan");
1228
1229 if (is_uv()) {
1230 ret = xpc_init_uv();
1231
1232 } else {
1233 ret = -ENODEV;
1234 }
1235
1236 if (ret != 0)
1237 return ret;
1238
1239 ret = xpc_setup_partitions();
1240 if (ret != 0) {
1241 dev_err(xpc_part, "can't get memory for partition structure\n");
1242 goto out_1;
1243 }
1244
1245 xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1246
1247 /*
1248 * Fill the partition reserved page with the information needed by
1249 * other partitions to discover we are alive and establish initial
1250 * communications.
1251 */
1252 ret = xpc_setup_rsvd_page();
1253 if (ret != 0) {
1254 dev_err(xpc_part, "can't setup our reserved page\n");
1255 goto out_2;
1256 }
1257
1258 /* add ourselves to the reboot_notifier_list */
1259 ret = register_reboot_notifier(&xpc_reboot_notifier);
1260 if (ret != 0)
1261 dev_warn(xpc_part, "can't register reboot notifier\n");
1262
1263 /* add ourselves to the die_notifier list */
1264 ret = register_die_notifier(&xpc_die_notifier);
1265 if (ret != 0)
1266 dev_warn(xpc_part, "can't register die notifier\n");
1267
1268 /*
1269 * The real work-horse behind xpc. This processes incoming
1270 * interrupts and monitors remote heartbeats.
1271 */
1272 kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1273 if (IS_ERR(kthread)) {
1274 dev_err(xpc_part, "failed while forking hb check thread\n");
1275 ret = -EBUSY;
1276 goto out_3;
1277 }
1278
1279 /*
1280 * Startup a thread that will attempt to discover other partitions to
1281 * activate based on info provided by SAL. This new thread is short
1282 * lived and will exit once discovery is complete.
1283 */
1284 kthread = kthread_run(xpc_initiate_discovery, NULL,
1285 XPC_DISCOVERY_THREAD_NAME);
1286 if (IS_ERR(kthread)) {
1287 dev_err(xpc_part, "failed while forking discovery thread\n");
1288
1289 /* mark this new thread as a non-starter */
1290 complete(&xpc_discovery_exited);
1291
1292 xpc_do_exit(xpUnloading);
1293 return -EBUSY;
1294 }
1295
1296 /* set the interface to point at XPC's functions */
1297 xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1298 xpc_initiate_send, xpc_initiate_send_notify,
1299 xpc_initiate_received, xpc_initiate_partid_to_nasids);
1300
1301 return 0;
1302
1303 /* initialization was not successful */
1304out_3:
1305 xpc_teardown_rsvd_page();
1306
1307 (void)unregister_die_notifier(&xpc_die_notifier);
1308 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1309out_2:
1310 if (xpc_sysctl)
1311 unregister_sysctl_table(xpc_sysctl);
1312
1313 xpc_teardown_partitions();
1314out_1:
1315 if (is_uv())
1316 xpc_exit_uv();
1317 return ret;
1318}
1319
1320module_init(xpc_init);
1321
1322void __exit
1323xpc_exit(void)
1324{
1325 xpc_do_exit(xpUnloading);
1326}
1327
1328module_exit(xpc_exit);
1329
1330MODULE_AUTHOR("Silicon Graphics, Inc.");
1331MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1332MODULE_LICENSE("GPL");
1333
1334module_param(xpc_hb_interval, int, 0);
1335MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1336 "heartbeat increments.");
1337
1338module_param(xpc_hb_check_interval, int, 0);
1339MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1340 "heartbeat checks.");
1341
1342module_param(xpc_disengage_timelimit, int, 0);
1343MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1344 "for disengage to complete.");
1345
1346module_param(xpc_kdebug_ignore, int, 0);
1347MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1348 "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 * (C) Copyright 2020 Hewlett Packard Enterprise Development LP
7 * Copyright (c) 2004-2009 Silicon Graphics, Inc. All Rights Reserved.
8 */
9
10/*
11 * Cross Partition Communication (XPC) support - standard version.
12 *
13 * XPC provides a message passing capability that crosses partition
14 * boundaries. This module is made up of two parts:
15 *
16 * partition This part detects the presence/absence of other
17 * partitions. It provides a heartbeat and monitors
18 * the heartbeats of other partitions.
19 *
20 * channel This part manages the channels and sends/receives
21 * messages across them to/from other partitions.
22 *
23 * There are a couple of additional functions residing in XP, which
24 * provide an interface to XPC for its users.
25 *
26 *
27 * Caveats:
28 *
29 * . Currently on sn2, we have no way to determine which nasid an IRQ
30 * came from. Thus, xpc_send_IRQ_sn2() does a remote amo write
31 * followed by an IPI. The amo indicates where data is to be pulled
32 * from, so after the IPI arrives, the remote partition checks the amo
33 * word. The IPI can actually arrive before the amo however, so other
34 * code must periodically check for this case. Also, remote amo
35 * operations do not reliably time out. Thus we do a remote PIO read
36 * solely to know whether the remote partition is down and whether we
37 * should stop sending IPIs to it. This remote PIO read operation is
38 * set up in a special nofault region so SAL knows to ignore (and
39 * cleanup) any errors due to the remote amo write, PIO read, and/or
40 * PIO write operations.
41 *
42 * If/when new hardware solves this IPI problem, we should abandon
43 * the current approach.
44 *
45 */
46
47#include <linux/module.h>
48#include <linux/slab.h>
49#include <linux/sysctl.h>
50#include <linux/device.h>
51#include <linux/delay.h>
52#include <linux/reboot.h>
53#include <linux/kdebug.h>
54#include <linux/kthread.h>
55#include "xpc.h"
56
57#ifdef CONFIG_X86_64
58#include <asm/traps.h>
59#endif
60
61/* define two XPC debug device structures to be used with dev_dbg() et al */
62
63static struct device_driver xpc_dbg_name = {
64 .name = "xpc"
65};
66
67static struct device xpc_part_dbg_subname = {
68 .init_name = "", /* set to "part" at xpc_init() time */
69 .driver = &xpc_dbg_name
70};
71
72static struct device xpc_chan_dbg_subname = {
73 .init_name = "", /* set to "chan" at xpc_init() time */
74 .driver = &xpc_dbg_name
75};
76
77struct device *xpc_part = &xpc_part_dbg_subname;
78struct device *xpc_chan = &xpc_chan_dbg_subname;
79
80static int xpc_kdebug_ignore;
81
82/* systune related variables for /proc/sys directories */
83
84static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
85static int xpc_hb_min_interval = 1;
86static int xpc_hb_max_interval = 10;
87
88static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
89static int xpc_hb_check_min_interval = 10;
90static int xpc_hb_check_max_interval = 120;
91
92int xpc_disengage_timelimit = XPC_DISENGAGE_DEFAULT_TIMELIMIT;
93static int xpc_disengage_min_timelimit; /* = 0 */
94static int xpc_disengage_max_timelimit = 120;
95
96static struct ctl_table xpc_sys_xpc_hb_dir[] = {
97 {
98 .procname = "hb_interval",
99 .data = &xpc_hb_interval,
100 .maxlen = sizeof(int),
101 .mode = 0644,
102 .proc_handler = proc_dointvec_minmax,
103 .extra1 = &xpc_hb_min_interval,
104 .extra2 = &xpc_hb_max_interval},
105 {
106 .procname = "hb_check_interval",
107 .data = &xpc_hb_check_interval,
108 .maxlen = sizeof(int),
109 .mode = 0644,
110 .proc_handler = proc_dointvec_minmax,
111 .extra1 = &xpc_hb_check_min_interval,
112 .extra2 = &xpc_hb_check_max_interval},
113 {}
114};
115static struct ctl_table xpc_sys_xpc_dir[] = {
116 {
117 .procname = "hb",
118 .mode = 0555,
119 .child = xpc_sys_xpc_hb_dir},
120 {
121 .procname = "disengage_timelimit",
122 .data = &xpc_disengage_timelimit,
123 .maxlen = sizeof(int),
124 .mode = 0644,
125 .proc_handler = proc_dointvec_minmax,
126 .extra1 = &xpc_disengage_min_timelimit,
127 .extra2 = &xpc_disengage_max_timelimit},
128 {}
129};
130static struct ctl_table xpc_sys_dir[] = {
131 {
132 .procname = "xpc",
133 .mode = 0555,
134 .child = xpc_sys_xpc_dir},
135 {}
136};
137static struct ctl_table_header *xpc_sysctl;
138
139/* non-zero if any remote partition disengage was timed out */
140int xpc_disengage_timedout;
141
142/* #of activate IRQs received and not yet processed */
143int xpc_activate_IRQ_rcvd;
144DEFINE_SPINLOCK(xpc_activate_IRQ_rcvd_lock);
145
146/* IRQ handler notifies this wait queue on receipt of an IRQ */
147DECLARE_WAIT_QUEUE_HEAD(xpc_activate_IRQ_wq);
148
149static unsigned long xpc_hb_check_timeout;
150static struct timer_list xpc_hb_timer;
151
152/* notification that the xpc_hb_checker thread has exited */
153static DECLARE_COMPLETION(xpc_hb_checker_exited);
154
155/* notification that the xpc_discovery thread has exited */
156static DECLARE_COMPLETION(xpc_discovery_exited);
157
158static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
159
160static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
161static struct notifier_block xpc_reboot_notifier = {
162 .notifier_call = xpc_system_reboot,
163};
164
165static int xpc_system_die(struct notifier_block *, unsigned long, void *);
166static struct notifier_block xpc_die_notifier = {
167 .notifier_call = xpc_system_die,
168};
169
170struct xpc_arch_operations xpc_arch_ops;
171
172/*
173 * Timer function to enforce the timelimit on the partition disengage.
174 */
175static void
176xpc_timeout_partition_disengage(struct timer_list *t)
177{
178 struct xpc_partition *part = from_timer(part, t, disengage_timer);
179
180 DBUG_ON(time_is_after_jiffies(part->disengage_timeout));
181
182 xpc_partition_disengaged_from_timer(part);
183
184 DBUG_ON(part->disengage_timeout != 0);
185 DBUG_ON(xpc_arch_ops.partition_engaged(XPC_PARTID(part)));
186}
187
188/*
189 * Timer to produce the heartbeat. The timer structures function is
190 * already set when this is initially called. A tunable is used to
191 * specify when the next timeout should occur.
192 */
193static void
194xpc_hb_beater(struct timer_list *unused)
195{
196 xpc_arch_ops.increment_heartbeat();
197
198 if (time_is_before_eq_jiffies(xpc_hb_check_timeout))
199 wake_up_interruptible(&xpc_activate_IRQ_wq);
200
201 xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
202 add_timer(&xpc_hb_timer);
203}
204
205static void
206xpc_start_hb_beater(void)
207{
208 xpc_arch_ops.heartbeat_init();
209 timer_setup(&xpc_hb_timer, xpc_hb_beater, 0);
210 xpc_hb_beater(NULL);
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 /* check for outstanding IRQs */
286 if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) {
287 force_IRQ = 0;
288 dev_dbg(xpc_part, "processing activate IRQs "
289 "received\n");
290 xpc_arch_ops.process_activate_IRQ_rcvd();
291 }
292
293 /* wait for IRQ or timeout */
294 (void)wait_event_interruptible(xpc_activate_IRQ_wq,
295 (time_is_before_eq_jiffies(
296 xpc_hb_check_timeout) ||
297 xpc_activate_IRQ_rcvd > 0 ||
298 xpc_exiting));
299 }
300
301 xpc_stop_hb_beater();
302
303 dev_dbg(xpc_part, "heartbeat checker is exiting\n");
304
305 /* mark this thread as having exited */
306 complete(&xpc_hb_checker_exited);
307 return 0;
308}
309
310/*
311 * This thread will attempt to discover other partitions to activate
312 * based on info provided by SAL. This new thread is short lived and
313 * will exit once discovery is complete.
314 */
315static int
316xpc_initiate_discovery(void *ignore)
317{
318 xpc_discovery();
319
320 dev_dbg(xpc_part, "discovery thread is exiting\n");
321
322 /* mark this thread as having exited */
323 complete(&xpc_discovery_exited);
324 return 0;
325}
326
327/*
328 * The first kthread assigned to a newly activated partition is the one
329 * created by XPC HB with which it calls xpc_activating(). XPC hangs on to
330 * that kthread until the partition is brought down, at which time that kthread
331 * returns back to XPC HB. (The return of that kthread will signify to XPC HB
332 * that XPC has dismantled all communication infrastructure for the associated
333 * partition.) This kthread becomes the channel manager for that partition.
334 *
335 * Each active partition has a channel manager, who, besides connecting and
336 * disconnecting channels, will ensure that each of the partition's connected
337 * channels has the required number of assigned kthreads to get the work done.
338 */
339static void
340xpc_channel_mgr(struct xpc_partition *part)
341{
342 while (part->act_state != XPC_P_AS_DEACTIVATING ||
343 atomic_read(&part->nchannels_active) > 0 ||
344 !xpc_partition_disengaged(part)) {
345
346 xpc_process_sent_chctl_flags(part);
347
348 /*
349 * Wait until we've been requested to activate kthreads or
350 * all of the channel's message queues have been torn down or
351 * a signal is pending.
352 *
353 * The channel_mgr_requests is set to 1 after being awakened,
354 * This is done to prevent the channel mgr from making one pass
355 * through the loop for each request, since he will
356 * be servicing all the requests in one pass. The reason it's
357 * set to 1 instead of 0 is so that other kthreads will know
358 * that the channel mgr is running and won't bother trying to
359 * wake him up.
360 */
361 atomic_dec(&part->channel_mgr_requests);
362 (void)wait_event_interruptible(part->channel_mgr_wq,
363 (atomic_read(&part->channel_mgr_requests) > 0 ||
364 part->chctl.all_flags != 0 ||
365 (part->act_state == XPC_P_AS_DEACTIVATING &&
366 atomic_read(&part->nchannels_active) == 0 &&
367 xpc_partition_disengaged(part))));
368 atomic_set(&part->channel_mgr_requests, 1);
369 }
370}
371
372/*
373 * Guarantee that the kzalloc'd memory is cacheline aligned.
374 */
375void *
376xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
377{
378 /* see if kzalloc will give us cachline aligned memory by default */
379 *base = kzalloc(size, flags);
380 if (*base == NULL)
381 return NULL;
382
383 if ((u64)*base == L1_CACHE_ALIGN((u64)*base))
384 return *base;
385
386 kfree(*base);
387
388 /* nope, we'll have to do it ourselves */
389 *base = kzalloc(size + L1_CACHE_BYTES, flags);
390 if (*base == NULL)
391 return NULL;
392
393 return (void *)L1_CACHE_ALIGN((u64)*base);
394}
395
396/*
397 * Setup the channel structures necessary to support XPartition Communication
398 * between the specified remote partition and the local one.
399 */
400static enum xp_retval
401xpc_setup_ch_structures(struct xpc_partition *part)
402{
403 enum xp_retval ret;
404 int ch_number;
405 struct xpc_channel *ch;
406 short partid = XPC_PARTID(part);
407
408 /*
409 * Allocate all of the channel structures as a contiguous chunk of
410 * memory.
411 */
412 DBUG_ON(part->channels != NULL);
413 part->channels = kcalloc(XPC_MAX_NCHANNELS,
414 sizeof(struct xpc_channel),
415 GFP_KERNEL);
416 if (part->channels == NULL) {
417 dev_err(xpc_chan, "can't get memory for channels\n");
418 return xpNoMemory;
419 }
420
421 /* allocate the remote open and close args */
422
423 part->remote_openclose_args =
424 xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
425 GFP_KERNEL, &part->
426 remote_openclose_args_base);
427 if (part->remote_openclose_args == NULL) {
428 dev_err(xpc_chan, "can't get memory for remote connect args\n");
429 ret = xpNoMemory;
430 goto out_1;
431 }
432
433 part->chctl.all_flags = 0;
434 spin_lock_init(&part->chctl_lock);
435
436 atomic_set(&part->channel_mgr_requests, 1);
437 init_waitqueue_head(&part->channel_mgr_wq);
438
439 part->nchannels = XPC_MAX_NCHANNELS;
440
441 atomic_set(&part->nchannels_active, 0);
442 atomic_set(&part->nchannels_engaged, 0);
443
444 for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
445 ch = &part->channels[ch_number];
446
447 ch->partid = partid;
448 ch->number = ch_number;
449 ch->flags = XPC_C_DISCONNECTED;
450
451 atomic_set(&ch->kthreads_assigned, 0);
452 atomic_set(&ch->kthreads_idle, 0);
453 atomic_set(&ch->kthreads_active, 0);
454
455 atomic_set(&ch->references, 0);
456 atomic_set(&ch->n_to_notify, 0);
457
458 spin_lock_init(&ch->lock);
459 init_completion(&ch->wdisconnect_wait);
460
461 atomic_set(&ch->n_on_msg_allocate_wq, 0);
462 init_waitqueue_head(&ch->msg_allocate_wq);
463 init_waitqueue_head(&ch->idle_wq);
464 }
465
466 ret = xpc_arch_ops.setup_ch_structures(part);
467 if (ret != xpSuccess)
468 goto out_2;
469
470 /*
471 * With the setting of the partition setup_state to XPC_P_SS_SETUP,
472 * we're declaring that this partition is ready to go.
473 */
474 part->setup_state = XPC_P_SS_SETUP;
475
476 return xpSuccess;
477
478 /* setup of ch structures failed */
479out_2:
480 kfree(part->remote_openclose_args_base);
481 part->remote_openclose_args = NULL;
482out_1:
483 kfree(part->channels);
484 part->channels = NULL;
485 return ret;
486}
487
488/*
489 * Teardown the channel structures necessary to support XPartition Communication
490 * between the specified remote partition and the local one.
491 */
492static void
493xpc_teardown_ch_structures(struct xpc_partition *part)
494{
495 DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
496 DBUG_ON(atomic_read(&part->nchannels_active) != 0);
497
498 /*
499 * Make this partition inaccessible to local processes by marking it
500 * as no longer setup. Then wait before proceeding with the teardown
501 * until all existing references cease.
502 */
503 DBUG_ON(part->setup_state != XPC_P_SS_SETUP);
504 part->setup_state = XPC_P_SS_WTEARDOWN;
505
506 wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
507
508 /* now we can begin tearing down the infrastructure */
509
510 xpc_arch_ops.teardown_ch_structures(part);
511
512 kfree(part->remote_openclose_args_base);
513 part->remote_openclose_args = NULL;
514 kfree(part->channels);
515 part->channels = NULL;
516
517 part->setup_state = XPC_P_SS_TORNDOWN;
518}
519
520/*
521 * When XPC HB determines that a partition has come up, it will create a new
522 * kthread and that kthread will call this function to attempt to set up the
523 * basic infrastructure used for Cross Partition Communication with the newly
524 * upped partition.
525 *
526 * The kthread that was created by XPC HB and which setup the XPC
527 * infrastructure will remain assigned to the partition becoming the channel
528 * manager for that partition until the partition is deactivating, at which
529 * time the kthread will teardown the XPC infrastructure and then exit.
530 */
531static int
532xpc_activating(void *__partid)
533{
534 short partid = (u64)__partid;
535 struct xpc_partition *part = &xpc_partitions[partid];
536 unsigned long irq_flags;
537
538 DBUG_ON(partid < 0 || partid >= xp_max_npartitions);
539
540 spin_lock_irqsave(&part->act_lock, irq_flags);
541
542 if (part->act_state == XPC_P_AS_DEACTIVATING) {
543 part->act_state = XPC_P_AS_INACTIVE;
544 spin_unlock_irqrestore(&part->act_lock, irq_flags);
545 part->remote_rp_pa = 0;
546 return 0;
547 }
548
549 /* indicate the thread is activating */
550 DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ);
551 part->act_state = XPC_P_AS_ACTIVATING;
552
553 XPC_SET_REASON(part, 0, 0);
554 spin_unlock_irqrestore(&part->act_lock, irq_flags);
555
556 dev_dbg(xpc_part, "activating partition %d\n", partid);
557
558 xpc_arch_ops.allow_hb(partid);
559
560 if (xpc_setup_ch_structures(part) == xpSuccess) {
561 (void)xpc_part_ref(part); /* this will always succeed */
562
563 if (xpc_arch_ops.make_first_contact(part) == xpSuccess) {
564 xpc_mark_partition_active(part);
565 xpc_channel_mgr(part);
566 /* won't return until partition is deactivating */
567 }
568
569 xpc_part_deref(part);
570 xpc_teardown_ch_structures(part);
571 }
572
573 xpc_arch_ops.disallow_hb(partid);
574 xpc_mark_partition_inactive(part);
575
576 if (part->reason == xpReactivating) {
577 /* interrupting ourselves results in activating partition */
578 xpc_arch_ops.request_partition_reactivation(part);
579 }
580
581 return 0;
582}
583
584void
585xpc_activate_partition(struct xpc_partition *part)
586{
587 short partid = XPC_PARTID(part);
588 unsigned long irq_flags;
589 struct task_struct *kthread;
590
591 spin_lock_irqsave(&part->act_lock, irq_flags);
592
593 DBUG_ON(part->act_state != XPC_P_AS_INACTIVE);
594
595 part->act_state = XPC_P_AS_ACTIVATION_REQ;
596 XPC_SET_REASON(part, xpCloneKThread, __LINE__);
597
598 spin_unlock_irqrestore(&part->act_lock, irq_flags);
599
600 kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d",
601 partid);
602 if (IS_ERR(kthread)) {
603 spin_lock_irqsave(&part->act_lock, irq_flags);
604 part->act_state = XPC_P_AS_INACTIVE;
605 XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__);
606 spin_unlock_irqrestore(&part->act_lock, irq_flags);
607 }
608}
609
610void
611xpc_activate_kthreads(struct xpc_channel *ch, int needed)
612{
613 int idle = atomic_read(&ch->kthreads_idle);
614 int assigned = atomic_read(&ch->kthreads_assigned);
615 int wakeup;
616
617 DBUG_ON(needed <= 0);
618
619 if (idle > 0) {
620 wakeup = (needed > idle) ? idle : needed;
621 needed -= wakeup;
622
623 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
624 "channel=%d\n", wakeup, ch->partid, ch->number);
625
626 /* only wakeup the requested number of kthreads */
627 wake_up_nr(&ch->idle_wq, wakeup);
628 }
629
630 if (needed <= 0)
631 return;
632
633 if (needed + assigned > ch->kthreads_assigned_limit) {
634 needed = ch->kthreads_assigned_limit - assigned;
635 if (needed <= 0)
636 return;
637 }
638
639 dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
640 needed, ch->partid, ch->number);
641
642 xpc_create_kthreads(ch, needed, 0);
643}
644
645/*
646 * This function is where XPC's kthreads wait for messages to deliver.
647 */
648static void
649xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
650{
651 int (*n_of_deliverable_payloads) (struct xpc_channel *) =
652 xpc_arch_ops.n_of_deliverable_payloads;
653
654 do {
655 /* deliver messages to their intended recipients */
656
657 while (n_of_deliverable_payloads(ch) > 0 &&
658 !(ch->flags & XPC_C_DISCONNECTING)) {
659 xpc_deliver_payload(ch);
660 }
661
662 if (atomic_inc_return(&ch->kthreads_idle) >
663 ch->kthreads_idle_limit) {
664 /* too many idle kthreads on this channel */
665 atomic_dec(&ch->kthreads_idle);
666 break;
667 }
668
669 dev_dbg(xpc_chan, "idle kthread calling "
670 "wait_event_interruptible_exclusive()\n");
671
672 (void)wait_event_interruptible_exclusive(ch->idle_wq,
673 (n_of_deliverable_payloads(ch) > 0 ||
674 (ch->flags & XPC_C_DISCONNECTING)));
675
676 atomic_dec(&ch->kthreads_idle);
677
678 } while (!(ch->flags & XPC_C_DISCONNECTING));
679}
680
681static int
682xpc_kthread_start(void *args)
683{
684 short partid = XPC_UNPACK_ARG1(args);
685 u16 ch_number = XPC_UNPACK_ARG2(args);
686 struct xpc_partition *part = &xpc_partitions[partid];
687 struct xpc_channel *ch;
688 int n_needed;
689 unsigned long irq_flags;
690 int (*n_of_deliverable_payloads) (struct xpc_channel *) =
691 xpc_arch_ops.n_of_deliverable_payloads;
692
693 dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
694 partid, ch_number);
695
696 ch = &part->channels[ch_number];
697
698 if (!(ch->flags & XPC_C_DISCONNECTING)) {
699
700 /* let registerer know that connection has been established */
701
702 spin_lock_irqsave(&ch->lock, irq_flags);
703 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
704 ch->flags |= XPC_C_CONNECTEDCALLOUT;
705 spin_unlock_irqrestore(&ch->lock, irq_flags);
706
707 xpc_connected_callout(ch);
708
709 spin_lock_irqsave(&ch->lock, irq_flags);
710 ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
711 spin_unlock_irqrestore(&ch->lock, irq_flags);
712
713 /*
714 * It is possible that while the callout was being
715 * made that the remote partition sent some messages.
716 * If that is the case, we may need to activate
717 * additional kthreads to help deliver them. We only
718 * need one less than total #of messages to deliver.
719 */
720 n_needed = n_of_deliverable_payloads(ch) - 1;
721 if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING))
722 xpc_activate_kthreads(ch, n_needed);
723
724 } else {
725 spin_unlock_irqrestore(&ch->lock, irq_flags);
726 }
727
728 xpc_kthread_waitmsgs(part, ch);
729 }
730
731 /* let registerer know that connection is disconnecting */
732
733 spin_lock_irqsave(&ch->lock, irq_flags);
734 if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
735 !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
736 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
737 spin_unlock_irqrestore(&ch->lock, irq_flags);
738
739 xpc_disconnect_callout(ch, xpDisconnecting);
740
741 spin_lock_irqsave(&ch->lock, irq_flags);
742 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
743 }
744 spin_unlock_irqrestore(&ch->lock, irq_flags);
745
746 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
747 atomic_dec_return(&part->nchannels_engaged) == 0) {
748 xpc_arch_ops.indicate_partition_disengaged(part);
749 }
750
751 xpc_msgqueue_deref(ch);
752
753 dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
754 partid, ch_number);
755
756 xpc_part_deref(part);
757 return 0;
758}
759
760/*
761 * For each partition that XPC has established communications with, there is
762 * a minimum of one kernel thread assigned to perform any operation that
763 * may potentially sleep or block (basically the callouts to the asynchronous
764 * functions registered via xpc_connect()).
765 *
766 * Additional kthreads are created and destroyed by XPC as the workload
767 * demands.
768 *
769 * A kthread is assigned to one of the active channels that exists for a given
770 * partition.
771 */
772void
773xpc_create_kthreads(struct xpc_channel *ch, int needed,
774 int ignore_disconnecting)
775{
776 unsigned long irq_flags;
777 u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
778 struct xpc_partition *part = &xpc_partitions[ch->partid];
779 struct task_struct *kthread;
780 void (*indicate_partition_disengaged) (struct xpc_partition *) =
781 xpc_arch_ops.indicate_partition_disengaged;
782
783 while (needed-- > 0) {
784
785 /*
786 * The following is done on behalf of the newly created
787 * kthread. That kthread is responsible for doing the
788 * counterpart to the following before it exits.
789 */
790 if (ignore_disconnecting) {
791 if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
792 /* kthreads assigned had gone to zero */
793 BUG_ON(!(ch->flags &
794 XPC_C_DISCONNECTINGCALLOUT_MADE));
795 break;
796 }
797
798 } else if (ch->flags & XPC_C_DISCONNECTING) {
799 break;
800
801 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
802 atomic_inc_return(&part->nchannels_engaged) == 1) {
803 xpc_arch_ops.indicate_partition_engaged(part);
804 }
805 (void)xpc_part_ref(part);
806 xpc_msgqueue_ref(ch);
807
808 kthread = kthread_run(xpc_kthread_start, (void *)args,
809 "xpc%02dc%d", ch->partid, ch->number);
810 if (IS_ERR(kthread)) {
811 /* the fork failed */
812
813 /*
814 * NOTE: if (ignore_disconnecting &&
815 * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
816 * then we'll deadlock if all other kthreads assigned
817 * to this channel are blocked in the channel's
818 * registerer, because the only thing that will unblock
819 * them is the xpDisconnecting callout that this
820 * failed kthread_run() would have made.
821 */
822
823 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
824 atomic_dec_return(&part->nchannels_engaged) == 0) {
825 indicate_partition_disengaged(part);
826 }
827 xpc_msgqueue_deref(ch);
828 xpc_part_deref(part);
829
830 if (atomic_read(&ch->kthreads_assigned) <
831 ch->kthreads_idle_limit) {
832 /*
833 * Flag this as an error only if we have an
834 * insufficient #of kthreads for the channel
835 * to function.
836 */
837 spin_lock_irqsave(&ch->lock, irq_flags);
838 XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources,
839 &irq_flags);
840 spin_unlock_irqrestore(&ch->lock, irq_flags);
841 }
842 break;
843 }
844 }
845}
846
847void
848xpc_disconnect_wait(int ch_number)
849{
850 unsigned long irq_flags;
851 short partid;
852 struct xpc_partition *part;
853 struct xpc_channel *ch;
854 int wakeup_channel_mgr;
855
856 /* now wait for all callouts to the caller's function to cease */
857 for (partid = 0; partid < xp_max_npartitions; partid++) {
858 part = &xpc_partitions[partid];
859
860 if (!xpc_part_ref(part))
861 continue;
862
863 ch = &part->channels[ch_number];
864
865 if (!(ch->flags & XPC_C_WDISCONNECT)) {
866 xpc_part_deref(part);
867 continue;
868 }
869
870 wait_for_completion(&ch->wdisconnect_wait);
871
872 spin_lock_irqsave(&ch->lock, irq_flags);
873 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
874 wakeup_channel_mgr = 0;
875
876 if (ch->delayed_chctl_flags) {
877 if (part->act_state != XPC_P_AS_DEACTIVATING) {
878 spin_lock(&part->chctl_lock);
879 part->chctl.flags[ch->number] |=
880 ch->delayed_chctl_flags;
881 spin_unlock(&part->chctl_lock);
882 wakeup_channel_mgr = 1;
883 }
884 ch->delayed_chctl_flags = 0;
885 }
886
887 ch->flags &= ~XPC_C_WDISCONNECT;
888 spin_unlock_irqrestore(&ch->lock, irq_flags);
889
890 if (wakeup_channel_mgr)
891 xpc_wakeup_channel_mgr(part);
892
893 xpc_part_deref(part);
894 }
895}
896
897static int
898xpc_setup_partitions(void)
899{
900 short partid;
901 struct xpc_partition *part;
902
903 xpc_partitions = kcalloc(xp_max_npartitions,
904 sizeof(struct xpc_partition),
905 GFP_KERNEL);
906 if (xpc_partitions == NULL) {
907 dev_err(xpc_part, "can't get memory for partition structure\n");
908 return -ENOMEM;
909 }
910
911 /*
912 * The first few fields of each entry of xpc_partitions[] need to
913 * be initialized now so that calls to xpc_connect() and
914 * xpc_disconnect() can be made prior to the activation of any remote
915 * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
916 * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
917 * PARTITION HAS BEEN ACTIVATED.
918 */
919 for (partid = 0; partid < xp_max_npartitions; partid++) {
920 part = &xpc_partitions[partid];
921
922 DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part));
923
924 part->activate_IRQ_rcvd = 0;
925 spin_lock_init(&part->act_lock);
926 part->act_state = XPC_P_AS_INACTIVE;
927 XPC_SET_REASON(part, 0, 0);
928
929 timer_setup(&part->disengage_timer,
930 xpc_timeout_partition_disengage, 0);
931
932 part->setup_state = XPC_P_SS_UNSET;
933 init_waitqueue_head(&part->teardown_wq);
934 atomic_set(&part->references, 0);
935 }
936
937 return xpc_arch_ops.setup_partitions();
938}
939
940static void
941xpc_teardown_partitions(void)
942{
943 xpc_arch_ops.teardown_partitions();
944 kfree(xpc_partitions);
945}
946
947static void
948xpc_do_exit(enum xp_retval reason)
949{
950 short partid;
951 int active_part_count, printed_waiting_msg = 0;
952 struct xpc_partition *part;
953 unsigned long printmsg_time, disengage_timeout = 0;
954
955 /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
956 DBUG_ON(xpc_exiting == 1);
957
958 /*
959 * Let the heartbeat checker thread and the discovery thread
960 * (if one is running) know that they should exit. Also wake up
961 * the heartbeat checker thread in case it's sleeping.
962 */
963 xpc_exiting = 1;
964 wake_up_interruptible(&xpc_activate_IRQ_wq);
965
966 /* wait for the discovery thread to exit */
967 wait_for_completion(&xpc_discovery_exited);
968
969 /* wait for the heartbeat checker thread to exit */
970 wait_for_completion(&xpc_hb_checker_exited);
971
972 /* sleep for a 1/3 of a second or so */
973 (void)msleep_interruptible(300);
974
975 /* wait for all partitions to become inactive */
976
977 printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
978 xpc_disengage_timedout = 0;
979
980 do {
981 active_part_count = 0;
982
983 for (partid = 0; partid < xp_max_npartitions; partid++) {
984 part = &xpc_partitions[partid];
985
986 if (xpc_partition_disengaged(part) &&
987 part->act_state == XPC_P_AS_INACTIVE) {
988 continue;
989 }
990
991 active_part_count++;
992
993 XPC_DEACTIVATE_PARTITION(part, reason);
994
995 if (part->disengage_timeout > disengage_timeout)
996 disengage_timeout = part->disengage_timeout;
997 }
998
999 if (xpc_arch_ops.any_partition_engaged()) {
1000 if (time_is_before_jiffies(printmsg_time)) {
1001 dev_info(xpc_part, "waiting for remote "
1002 "partitions to deactivate, timeout in "
1003 "%ld seconds\n", (disengage_timeout -
1004 jiffies) / HZ);
1005 printmsg_time = jiffies +
1006 (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ);
1007 printed_waiting_msg = 1;
1008 }
1009
1010 } else if (active_part_count > 0) {
1011 if (printed_waiting_msg) {
1012 dev_info(xpc_part, "waiting for local partition"
1013 " to deactivate\n");
1014 printed_waiting_msg = 0;
1015 }
1016
1017 } else {
1018 if (!xpc_disengage_timedout) {
1019 dev_info(xpc_part, "all partitions have "
1020 "deactivated\n");
1021 }
1022 break;
1023 }
1024
1025 /* sleep for a 1/3 of a second or so */
1026 (void)msleep_interruptible(300);
1027
1028 } while (1);
1029
1030 DBUG_ON(xpc_arch_ops.any_partition_engaged());
1031
1032 xpc_teardown_rsvd_page();
1033
1034 if (reason == xpUnloading) {
1035 (void)unregister_die_notifier(&xpc_die_notifier);
1036 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1037 }
1038
1039 /* clear the interface to XPC's functions */
1040 xpc_clear_interface();
1041
1042 if (xpc_sysctl)
1043 unregister_sysctl_table(xpc_sysctl);
1044
1045 xpc_teardown_partitions();
1046
1047 if (is_uv_system())
1048 xpc_exit_uv();
1049}
1050
1051/*
1052 * This function is called when the system is being rebooted.
1053 */
1054static int
1055xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1056{
1057 enum xp_retval reason;
1058
1059 switch (event) {
1060 case SYS_RESTART:
1061 reason = xpSystemReboot;
1062 break;
1063 case SYS_HALT:
1064 reason = xpSystemHalt;
1065 break;
1066 case SYS_POWER_OFF:
1067 reason = xpSystemPoweroff;
1068 break;
1069 default:
1070 reason = xpSystemGoingDown;
1071 }
1072
1073 xpc_do_exit(reason);
1074 return NOTIFY_DONE;
1075}
1076
1077/* Used to only allow one cpu to complete disconnect */
1078static unsigned int xpc_die_disconnecting;
1079
1080/*
1081 * Notify other partitions to deactivate from us by first disengaging from all
1082 * references to our memory.
1083 */
1084static void
1085xpc_die_deactivate(void)
1086{
1087 struct xpc_partition *part;
1088 short partid;
1089 int any_engaged;
1090 long keep_waiting;
1091 long wait_to_print;
1092
1093 if (cmpxchg(&xpc_die_disconnecting, 0, 1))
1094 return;
1095
1096 /* keep xpc_hb_checker thread from doing anything (just in case) */
1097 xpc_exiting = 1;
1098
1099 xpc_arch_ops.disallow_all_hbs(); /*indicate we're deactivated */
1100
1101 for (partid = 0; partid < xp_max_npartitions; partid++) {
1102 part = &xpc_partitions[partid];
1103
1104 if (xpc_arch_ops.partition_engaged(partid) ||
1105 part->act_state != XPC_P_AS_INACTIVE) {
1106 xpc_arch_ops.request_partition_deactivation(part);
1107 xpc_arch_ops.indicate_partition_disengaged(part);
1108 }
1109 }
1110
1111 /*
1112 * Though we requested that all other partitions deactivate from us,
1113 * we only wait until they've all disengaged or we've reached the
1114 * defined timelimit.
1115 *
1116 * Given that one iteration through the following while-loop takes
1117 * approximately 200 microseconds, calculate the #of loops to take
1118 * before bailing and the #of loops before printing a waiting message.
1119 */
1120 keep_waiting = xpc_disengage_timelimit * 1000 * 5;
1121 wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5;
1122
1123 while (1) {
1124 any_engaged = xpc_arch_ops.any_partition_engaged();
1125 if (!any_engaged) {
1126 dev_info(xpc_part, "all partitions have deactivated\n");
1127 break;
1128 }
1129
1130 if (!keep_waiting--) {
1131 for (partid = 0; partid < xp_max_npartitions;
1132 partid++) {
1133 if (xpc_arch_ops.partition_engaged(partid)) {
1134 dev_info(xpc_part, "deactivate from "
1135 "remote partition %d timed "
1136 "out\n", partid);
1137 }
1138 }
1139 break;
1140 }
1141
1142 if (!wait_to_print--) {
1143 dev_info(xpc_part, "waiting for remote partitions to "
1144 "deactivate, timeout in %ld seconds\n",
1145 keep_waiting / (1000 * 5));
1146 wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL *
1147 1000 * 5;
1148 }
1149
1150 udelay(200);
1151 }
1152}
1153
1154/*
1155 * This function is called when the system is being restarted or halted due
1156 * to some sort of system failure. If this is the case we need to notify the
1157 * other partitions to disengage from all references to our memory.
1158 * This function can also be called when our heartbeater could be offlined
1159 * for a time. In this case we need to notify other partitions to not worry
1160 * about the lack of a heartbeat.
1161 */
1162static int
1163xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args)
1164{
1165#ifdef CONFIG_IA64 /* !!! temporary kludge */
1166 switch (event) {
1167 case DIE_MACHINE_RESTART:
1168 case DIE_MACHINE_HALT:
1169 xpc_die_deactivate();
1170 break;
1171
1172 case DIE_KDEBUG_ENTER:
1173 /* Should lack of heartbeat be ignored by other partitions? */
1174 if (!xpc_kdebug_ignore)
1175 break;
1176
1177 fallthrough;
1178 case DIE_MCA_MONARCH_ENTER:
1179 case DIE_INIT_MONARCH_ENTER:
1180 xpc_arch_ops.offline_heartbeat();
1181 break;
1182
1183 case DIE_KDEBUG_LEAVE:
1184 /* Is lack of heartbeat being ignored by other partitions? */
1185 if (!xpc_kdebug_ignore)
1186 break;
1187
1188 fallthrough;
1189 case DIE_MCA_MONARCH_LEAVE:
1190 case DIE_INIT_MONARCH_LEAVE:
1191 xpc_arch_ops.online_heartbeat();
1192 break;
1193 }
1194#else
1195 struct die_args *die_args = _die_args;
1196
1197 switch (event) {
1198 case DIE_TRAP:
1199 if (die_args->trapnr == X86_TRAP_DF)
1200 xpc_die_deactivate();
1201
1202 if (((die_args->trapnr == X86_TRAP_MF) ||
1203 (die_args->trapnr == X86_TRAP_XF)) &&
1204 !user_mode(die_args->regs))
1205 xpc_die_deactivate();
1206
1207 break;
1208 case DIE_INT3:
1209 case DIE_DEBUG:
1210 break;
1211 case DIE_OOPS:
1212 case DIE_GPF:
1213 default:
1214 xpc_die_deactivate();
1215 }
1216#endif
1217
1218 return NOTIFY_DONE;
1219}
1220
1221static int __init
1222xpc_init(void)
1223{
1224 int ret;
1225 struct task_struct *kthread;
1226
1227 dev_set_name(xpc_part, "part");
1228 dev_set_name(xpc_chan, "chan");
1229
1230 if (is_uv_system()) {
1231 ret = xpc_init_uv();
1232
1233 } else {
1234 ret = -ENODEV;
1235 }
1236
1237 if (ret != 0)
1238 return ret;
1239
1240 ret = xpc_setup_partitions();
1241 if (ret != 0) {
1242 dev_err(xpc_part, "can't get memory for partition structure\n");
1243 goto out_1;
1244 }
1245
1246 xpc_sysctl = register_sysctl_table(xpc_sys_dir);
1247
1248 /*
1249 * Fill the partition reserved page with the information needed by
1250 * other partitions to discover we are alive and establish initial
1251 * communications.
1252 */
1253 ret = xpc_setup_rsvd_page();
1254 if (ret != 0) {
1255 dev_err(xpc_part, "can't setup our reserved page\n");
1256 goto out_2;
1257 }
1258
1259 /* add ourselves to the reboot_notifier_list */
1260 ret = register_reboot_notifier(&xpc_reboot_notifier);
1261 if (ret != 0)
1262 dev_warn(xpc_part, "can't register reboot notifier\n");
1263
1264 /* add ourselves to the die_notifier list */
1265 ret = register_die_notifier(&xpc_die_notifier);
1266 if (ret != 0)
1267 dev_warn(xpc_part, "can't register die notifier\n");
1268
1269 /*
1270 * The real work-horse behind xpc. This processes incoming
1271 * interrupts and monitors remote heartbeats.
1272 */
1273 kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME);
1274 if (IS_ERR(kthread)) {
1275 dev_err(xpc_part, "failed while forking hb check thread\n");
1276 ret = -EBUSY;
1277 goto out_3;
1278 }
1279
1280 /*
1281 * Startup a thread that will attempt to discover other partitions to
1282 * activate based on info provided by SAL. This new thread is short
1283 * lived and will exit once discovery is complete.
1284 */
1285 kthread = kthread_run(xpc_initiate_discovery, NULL,
1286 XPC_DISCOVERY_THREAD_NAME);
1287 if (IS_ERR(kthread)) {
1288 dev_err(xpc_part, "failed while forking discovery thread\n");
1289
1290 /* mark this new thread as a non-starter */
1291 complete(&xpc_discovery_exited);
1292
1293 xpc_do_exit(xpUnloading);
1294 return -EBUSY;
1295 }
1296
1297 /* set the interface to point at XPC's functions */
1298 xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1299 xpc_initiate_send, xpc_initiate_send_notify,
1300 xpc_initiate_received, xpc_initiate_partid_to_nasids);
1301
1302 return 0;
1303
1304 /* initialization was not successful */
1305out_3:
1306 xpc_teardown_rsvd_page();
1307
1308 (void)unregister_die_notifier(&xpc_die_notifier);
1309 (void)unregister_reboot_notifier(&xpc_reboot_notifier);
1310out_2:
1311 if (xpc_sysctl)
1312 unregister_sysctl_table(xpc_sysctl);
1313
1314 xpc_teardown_partitions();
1315out_1:
1316 if (is_uv_system())
1317 xpc_exit_uv();
1318 return ret;
1319}
1320
1321module_init(xpc_init);
1322
1323static void __exit
1324xpc_exit(void)
1325{
1326 xpc_do_exit(xpUnloading);
1327}
1328
1329module_exit(xpc_exit);
1330
1331MODULE_AUTHOR("Silicon Graphics, Inc.");
1332MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1333MODULE_LICENSE("GPL");
1334
1335module_param(xpc_hb_interval, int, 0);
1336MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1337 "heartbeat increments.");
1338
1339module_param(xpc_hb_check_interval, int, 0);
1340MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1341 "heartbeat checks.");
1342
1343module_param(xpc_disengage_timelimit, int, 0);
1344MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait "
1345 "for disengage to complete.");
1346
1347module_param(xpc_kdebug_ignore, int, 0);
1348MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1349 "other partitions when dropping into kdebug.");