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
6 * Copyright (c) 2004-2006 Silicon Graphics, Inc. All Rights Reserved.
11 * Cross Partition Communication (XPC) support - standard version.
13 * XPC provides a message passing capability that crosses partition
14 * boundaries. This module is made up of two parts:
16 * partition This part detects the presence/absence of other
17 * partitions. It provides a heartbeat and monitors
18 * the heartbeats of other partitions.
20 * channel This part manages the channels and sends/receives
21 * messages across them to/from other partitions.
23 * There are a couple of additional functions residing in XP, which
24 * provide an interface to XPC for its users.
29 * . We currently have no way to determine which nasid an IPI came
30 * from. Thus, xpc_IPI_send() does a remote AMO write followed by
31 * an IPI. The AMO indicates where data is to be pulled from, so
32 * after the IPI arrives, the remote partition checks the AMO word.
33 * The IPI can actually arrive before the AMO however, so other code
34 * must periodically check for this case. Also, remote AMO operations
35 * do not reliably time out. Thus we do a remote PIO read solely to
36 * know whether the remote partition is down and whether we should
37 * stop sending IPIs to it. This remote PIO read operation is set up
38 * in a special nofault region so SAL knows to ignore (and cleanup)
39 * any errors due to the remote AMO write, PIO read, and/or PIO
42 * If/when new hardware solves this IPI problem, we should abandon
43 * the current approach.
48 #include <linux/kernel.h>
49 #include <linux/module.h>
50 #include <linux/init.h>
51 #include <linux/sched.h>
52 #include <linux/syscalls.h>
53 #include <linux/cache.h>
54 #include <linux/interrupt.h>
55 #include <linux/delay.h>
56 #include <linux/reboot.h>
57 #include <linux/completion.h>
58 #include <asm/sn/intr.h>
59 #include <asm/sn/sn_sal.h>
60 #include <asm/kdebug.h>
61 #include <asm/uaccess.h>
62 #include <asm/sn/xpc.h>
65 /* define two XPC debug device structures to be used with dev_dbg() et al */
67 struct device_driver xpc_dbg_name = {
71 struct device xpc_part_dbg_subname = {
72 .bus_id = {0}, /* set to "part" at xpc_init() time */
73 .driver = &xpc_dbg_name
76 struct device xpc_chan_dbg_subname = {
77 .bus_id = {0}, /* set to "chan" at xpc_init() time */
78 .driver = &xpc_dbg_name
81 struct device *xpc_part = &xpc_part_dbg_subname;
82 struct device *xpc_chan = &xpc_chan_dbg_subname;
85 static int xpc_kdebug_ignore;
88 /* systune related variables for /proc/sys directories */
90 static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
91 static int xpc_hb_min_interval = 1;
92 static int xpc_hb_max_interval = 10;
94 static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
95 static int xpc_hb_check_min_interval = 10;
96 static int xpc_hb_check_max_interval = 120;
98 int xpc_disengage_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
99 static int xpc_disengage_request_min_timelimit = 0;
100 static int xpc_disengage_request_max_timelimit = 120;
102 static ctl_table xpc_sys_xpc_hb_dir[] = {
110 &proc_dointvec_minmax,
113 &xpc_hb_min_interval,
119 &xpc_hb_check_interval,
123 &proc_dointvec_minmax,
126 &xpc_hb_check_min_interval,
127 &xpc_hb_check_max_interval
131 static ctl_table xpc_sys_xpc_dir[] = {
142 "disengage_request_timelimit",
143 &xpc_disengage_request_timelimit,
147 &proc_dointvec_minmax,
150 &xpc_disengage_request_min_timelimit,
151 &xpc_disengage_request_max_timelimit
155 static ctl_table xpc_sys_dir[] = {
166 static struct ctl_table_header *xpc_sysctl;
168 /* non-zero if any remote partition disengage request was timed out */
169 int xpc_disengage_request_timedout;
171 /* #of IRQs received */
172 static atomic_t xpc_act_IRQ_rcvd;
174 /* IRQ handler notifies this wait queue on receipt of an IRQ */
175 static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
177 static unsigned long xpc_hb_check_timeout;
179 /* notification that the xpc_hb_checker thread has exited */
180 static DECLARE_COMPLETION(xpc_hb_checker_exited);
182 /* notification that the xpc_discovery thread has exited */
183 static DECLARE_COMPLETION(xpc_discovery_exited);
186 static struct timer_list xpc_hb_timer;
189 static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
192 static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
193 static struct notifier_block xpc_reboot_notifier = {
194 .notifier_call = xpc_system_reboot,
197 static int xpc_system_die(struct notifier_block *, unsigned long, void *);
198 static struct notifier_block xpc_die_notifier = {
199 .notifier_call = xpc_system_die,
204 * Timer function to enforce the timelimit on the partition disengage request.
207 xpc_timeout_partition_disengage_request(unsigned long data)
209 struct xpc_partition *part = (struct xpc_partition *) data;
212 DBUG_ON(jiffies < part->disengage_request_timeout);
214 (void) xpc_partition_disengaged(part);
216 DBUG_ON(part->disengage_request_timeout != 0);
217 DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
222 * Notify the heartbeat check thread that an IRQ has been received.
225 xpc_act_IRQ_handler(int irq, void *dev_id)
227 atomic_inc(&xpc_act_IRQ_rcvd);
228 wake_up_interruptible(&xpc_act_IRQ_wq);
234 * Timer to produce the heartbeat. The timer structures function is
235 * already set when this is initially called. A tunable is used to
236 * specify when the next timeout should occur.
239 xpc_hb_beater(unsigned long dummy)
241 xpc_vars->heartbeat++;
243 if (jiffies >= xpc_hb_check_timeout) {
244 wake_up_interruptible(&xpc_act_IRQ_wq);
247 xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
248 add_timer(&xpc_hb_timer);
253 * This thread is responsible for nearly all of the partition
254 * activation/deactivation.
257 xpc_hb_checker(void *ignore)
259 int last_IRQ_count = 0;
264 /* this thread was marked active by xpc_hb_init() */
266 daemonize(XPC_HB_CHECK_THREAD_NAME);
268 set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
270 xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
272 while (!(volatile int) xpc_exiting) {
274 dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
276 (int) (xpc_hb_check_timeout - jiffies),
277 atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
280 /* checking of remote heartbeats is skewed by IRQ handling */
281 if (jiffies >= xpc_hb_check_timeout) {
282 dev_dbg(xpc_part, "checking remote heartbeats\n");
283 xpc_check_remote_hb();
286 * We need to periodically recheck to ensure no
287 * IPI/AMO pairs have been missed. That check
288 * must always reset xpc_hb_check_timeout.
294 /* check for outstanding IRQs */
295 new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
296 if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
299 dev_dbg(xpc_part, "found an IRQ to process; will be "
300 "resetting xpc_hb_check_timeout\n");
302 last_IRQ_count += xpc_identify_act_IRQ_sender();
303 if (last_IRQ_count < new_IRQ_count) {
304 /* retry once to help avoid missing AMO */
305 (void) xpc_identify_act_IRQ_sender();
307 last_IRQ_count = new_IRQ_count;
309 xpc_hb_check_timeout = jiffies +
310 (xpc_hb_check_interval * HZ);
313 /* wait for IRQ or timeout */
314 (void) wait_event_interruptible(xpc_act_IRQ_wq,
315 (last_IRQ_count < atomic_read(&xpc_act_IRQ_rcvd) ||
316 jiffies >= xpc_hb_check_timeout ||
317 (volatile int) xpc_exiting));
320 dev_dbg(xpc_part, "heartbeat checker is exiting\n");
323 /* mark this thread as having exited */
324 complete(&xpc_hb_checker_exited);
330 * This thread will attempt to discover other partitions to activate
331 * based on info provided by SAL. This new thread is short lived and
332 * will exit once discovery is complete.
335 xpc_initiate_discovery(void *ignore)
337 daemonize(XPC_DISCOVERY_THREAD_NAME);
341 dev_dbg(xpc_part, "discovery thread is exiting\n");
343 /* mark this thread as having exited */
344 complete(&xpc_discovery_exited);
350 * Establish first contact with the remote partititon. This involves pulling
351 * the XPC per partition variables from the remote partition and waiting for
352 * the remote partition to pull ours.
354 static enum xpc_retval
355 xpc_make_first_contact(struct xpc_partition *part)
360 while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
361 if (ret != xpcRetry) {
362 XPC_DEACTIVATE_PARTITION(part, ret);
366 dev_dbg(xpc_chan, "waiting to make first contact with "
367 "partition %d\n", XPC_PARTID(part));
369 /* wait a 1/4 of a second or so */
370 (void) msleep_interruptible(250);
372 if (part->act_state == XPC_P_DEACTIVATING) {
377 return xpc_mark_partition_active(part);
382 * The first kthread assigned to a newly activated partition is the one
383 * created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
384 * that kthread until the partition is brought down, at which time that kthread
385 * returns back to XPC HB. (The return of that kthread will signify to XPC HB
386 * that XPC has dismantled all communication infrastructure for the associated
387 * partition.) This kthread becomes the channel manager for that partition.
389 * Each active partition has a channel manager, who, besides connecting and
390 * disconnecting channels, will ensure that each of the partition's connected
391 * channels has the required number of assigned kthreads to get the work done.
394 xpc_channel_mgr(struct xpc_partition *part)
396 while (part->act_state != XPC_P_DEACTIVATING ||
397 atomic_read(&part->nchannels_active) > 0 ||
398 !xpc_partition_disengaged(part)) {
400 xpc_process_channel_activity(part);
404 * Wait until we've been requested to activate kthreads or
405 * all of the channel's message queues have been torn down or
406 * a signal is pending.
408 * The channel_mgr_requests is set to 1 after being awakened,
409 * This is done to prevent the channel mgr from making one pass
410 * through the loop for each request, since he will
411 * be servicing all the requests in one pass. The reason it's
412 * set to 1 instead of 0 is so that other kthreads will know
413 * that the channel mgr is running and won't bother trying to
416 atomic_dec(&part->channel_mgr_requests);
417 (void) wait_event_interruptible(part->channel_mgr_wq,
418 (atomic_read(&part->channel_mgr_requests) > 0 ||
419 (volatile u64) part->local_IPI_amo != 0 ||
420 ((volatile u8) part->act_state ==
421 XPC_P_DEACTIVATING &&
422 atomic_read(&part->nchannels_active) == 0 &&
423 xpc_partition_disengaged(part))));
424 atomic_set(&part->channel_mgr_requests, 1);
426 // >>> Does it need to wakeup periodically as well? In case we
427 // >>> miscalculated the #of kthreads to wakeup or create?
433 * When XPC HB determines that a partition has come up, it will create a new
434 * kthread and that kthread will call this function to attempt to set up the
435 * basic infrastructure used for Cross Partition Communication with the newly
438 * The kthread that was created by XPC HB and which setup the XPC
439 * infrastructure will remain assigned to the partition until the partition
440 * goes down. At which time the kthread will teardown the XPC infrastructure
443 * XPC HB will put the remote partition's XPC per partition specific variables
444 * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
445 * calling xpc_partition_up().
448 xpc_partition_up(struct xpc_partition *part)
450 DBUG_ON(part->channels != NULL);
452 dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
454 if (xpc_setup_infrastructure(part) != xpcSuccess) {
459 * The kthread that XPC HB called us with will become the
460 * channel manager for this partition. It will not return
461 * back to XPC HB until the partition's XPC infrastructure
462 * has been dismantled.
465 (void) xpc_part_ref(part); /* this will always succeed */
467 if (xpc_make_first_contact(part) == xpcSuccess) {
468 xpc_channel_mgr(part);
471 xpc_part_deref(part);
473 xpc_teardown_infrastructure(part);
478 xpc_activating(void *__partid)
480 partid_t partid = (u64) __partid;
481 struct xpc_partition *part = &xpc_partitions[partid];
482 unsigned long irq_flags;
483 struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
487 DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
489 spin_lock_irqsave(&part->act_lock, irq_flags);
491 if (part->act_state == XPC_P_DEACTIVATING) {
492 part->act_state = XPC_P_INACTIVE;
493 spin_unlock_irqrestore(&part->act_lock, irq_flags);
494 part->remote_rp_pa = 0;
498 /* indicate the thread is activating */
499 DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
500 part->act_state = XPC_P_ACTIVATING;
502 XPC_SET_REASON(part, 0, 0);
503 spin_unlock_irqrestore(&part->act_lock, irq_flags);
505 dev_dbg(xpc_part, "bringing partition %d up\n", partid);
507 daemonize("xpc%02d", partid);
510 * This thread needs to run at a realtime priority to prevent a
511 * significant performance degradation.
513 ret = sched_setscheduler(current, SCHED_FIFO, ¶m);
515 dev_warn(xpc_part, "unable to set pid %d to a realtime "
516 "priority, ret=%d\n", current->pid, ret);
519 /* allow this thread and its children to run on any CPU */
520 set_cpus_allowed(current, CPU_MASK_ALL);
523 * Register the remote partition's AMOs with SAL so it can handle
524 * and cleanup errors within that address range should the remote
525 * partition go down. We don't unregister this range because it is
526 * difficult to tell when outstanding writes to the remote partition
527 * are finished and thus when it is safe to unregister. This should
528 * not result in wasted space in the SAL xp_addr_region table because
529 * we should get the same page for remote_amos_page_pa after module
530 * reloads and system reboots.
532 if (sn_register_xp_addr_region(part->remote_amos_page_pa,
534 dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
535 "xp_addr region\n", partid);
537 spin_lock_irqsave(&part->act_lock, irq_flags);
538 part->act_state = XPC_P_INACTIVE;
539 XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
540 spin_unlock_irqrestore(&part->act_lock, irq_flags);
541 part->remote_rp_pa = 0;
545 xpc_allow_hb(partid, xpc_vars);
546 xpc_IPI_send_activated(part);
550 * xpc_partition_up() holds this thread and marks this partition as
551 * XPC_P_ACTIVE by calling xpc_hb_mark_active().
553 (void) xpc_partition_up(part);
555 xpc_disallow_hb(partid, xpc_vars);
556 xpc_mark_partition_inactive(part);
558 if (part->reason == xpcReactivating) {
559 /* interrupting ourselves results in activating partition */
560 xpc_IPI_send_reactivate(part);
568 xpc_activate_partition(struct xpc_partition *part)
570 partid_t partid = XPC_PARTID(part);
571 unsigned long irq_flags;
575 spin_lock_irqsave(&part->act_lock, irq_flags);
577 DBUG_ON(part->act_state != XPC_P_INACTIVE);
579 part->act_state = XPC_P_ACTIVATION_REQ;
580 XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
582 spin_unlock_irqrestore(&part->act_lock, irq_flags);
584 pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
586 if (unlikely(pid <= 0)) {
587 spin_lock_irqsave(&part->act_lock, irq_flags);
588 part->act_state = XPC_P_INACTIVE;
589 XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
590 spin_unlock_irqrestore(&part->act_lock, irq_flags);
596 * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
597 * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
598 * than one partition, we use an AMO_t structure per partition to indicate
599 * whether a partition has sent an IPI or not. >>> If it has, then wake up the
600 * associated kthread to handle it.
602 * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
603 * running on other partitions.
605 * Noteworthy Arguments:
607 * irq - Interrupt ReQuest number. NOT USED.
609 * dev_id - partid of IPI's potential sender.
612 xpc_notify_IRQ_handler(int irq, void *dev_id)
614 partid_t partid = (partid_t) (u64) dev_id;
615 struct xpc_partition *part = &xpc_partitions[partid];
618 DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
620 if (xpc_part_ref(part)) {
621 xpc_check_for_channel_activity(part);
623 xpc_part_deref(part);
630 * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
631 * because the write to their associated IPI amo completed after the IRQ/IPI
635 xpc_dropped_IPI_check(struct xpc_partition *part)
637 if (xpc_part_ref(part)) {
638 xpc_check_for_channel_activity(part);
640 part->dropped_IPI_timer.expires = jiffies +
641 XPC_P_DROPPED_IPI_WAIT;
642 add_timer(&part->dropped_IPI_timer);
643 xpc_part_deref(part);
649 xpc_activate_kthreads(struct xpc_channel *ch, int needed)
651 int idle = atomic_read(&ch->kthreads_idle);
652 int assigned = atomic_read(&ch->kthreads_assigned);
656 DBUG_ON(needed <= 0);
659 wakeup = (needed > idle) ? idle : needed;
662 dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
663 "channel=%d\n", wakeup, ch->partid, ch->number);
665 /* only wakeup the requested number of kthreads */
666 wake_up_nr(&ch->idle_wq, wakeup);
673 if (needed + assigned > ch->kthreads_assigned_limit) {
674 needed = ch->kthreads_assigned_limit - assigned;
675 // >>>should never be less than 0
681 dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
682 needed, ch->partid, ch->number);
684 xpc_create_kthreads(ch, needed, 0);
689 * This function is where XPC's kthreads wait for messages to deliver.
692 xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
695 /* deliver messages to their intended recipients */
697 while ((volatile s64) ch->w_local_GP.get <
698 (volatile s64) ch->w_remote_GP.put &&
699 !((volatile u32) ch->flags &
700 XPC_C_DISCONNECTING)) {
704 if (atomic_inc_return(&ch->kthreads_idle) >
705 ch->kthreads_idle_limit) {
706 /* too many idle kthreads on this channel */
707 atomic_dec(&ch->kthreads_idle);
711 dev_dbg(xpc_chan, "idle kthread calling "
712 "wait_event_interruptible_exclusive()\n");
714 (void) wait_event_interruptible_exclusive(ch->idle_wq,
715 ((volatile s64) ch->w_local_GP.get <
716 (volatile s64) ch->w_remote_GP.put ||
717 ((volatile u32) ch->flags &
718 XPC_C_DISCONNECTING)));
720 atomic_dec(&ch->kthreads_idle);
722 } while (!((volatile u32) ch->flags & XPC_C_DISCONNECTING));
727 xpc_daemonize_kthread(void *args)
729 partid_t partid = XPC_UNPACK_ARG1(args);
730 u16 ch_number = XPC_UNPACK_ARG2(args);
731 struct xpc_partition *part = &xpc_partitions[partid];
732 struct xpc_channel *ch;
734 unsigned long irq_flags;
737 daemonize("xpc%02dc%d", partid, ch_number);
739 dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
742 ch = &part->channels[ch_number];
744 if (!(ch->flags & XPC_C_DISCONNECTING)) {
746 /* let registerer know that connection has been established */
748 spin_lock_irqsave(&ch->lock, irq_flags);
749 if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
750 ch->flags |= XPC_C_CONNECTEDCALLOUT;
751 spin_unlock_irqrestore(&ch->lock, irq_flags);
753 xpc_connected_callout(ch);
755 spin_lock_irqsave(&ch->lock, irq_flags);
756 ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
757 spin_unlock_irqrestore(&ch->lock, irq_flags);
760 * It is possible that while the callout was being
761 * made that the remote partition sent some messages.
762 * If that is the case, we may need to activate
763 * additional kthreads to help deliver them. We only
764 * need one less than total #of messages to deliver.
766 n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
768 !(ch->flags & XPC_C_DISCONNECTING)) {
769 xpc_activate_kthreads(ch, n_needed);
772 spin_unlock_irqrestore(&ch->lock, irq_flags);
775 xpc_kthread_waitmsgs(part, ch);
778 /* let registerer know that connection is disconnecting */
780 spin_lock_irqsave(&ch->lock, irq_flags);
781 if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
782 !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
783 ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
784 spin_unlock_irqrestore(&ch->lock, irq_flags);
786 xpc_disconnect_callout(ch, xpcDisconnecting);
788 spin_lock_irqsave(&ch->lock, irq_flags);
789 ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
791 spin_unlock_irqrestore(&ch->lock, irq_flags);
793 if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
794 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
795 xpc_mark_partition_disengaged(part);
796 xpc_IPI_send_disengage(part);
800 xpc_msgqueue_deref(ch);
802 dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
805 xpc_part_deref(part);
811 * For each partition that XPC has established communications with, there is
812 * a minimum of one kernel thread assigned to perform any operation that
813 * may potentially sleep or block (basically the callouts to the asynchronous
814 * functions registered via xpc_connect()).
816 * Additional kthreads are created and destroyed by XPC as the workload
819 * A kthread is assigned to one of the active channels that exists for a given
823 xpc_create_kthreads(struct xpc_channel *ch, int needed,
824 int ignore_disconnecting)
826 unsigned long irq_flags;
828 u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
829 struct xpc_partition *part = &xpc_partitions[ch->partid];
832 while (needed-- > 0) {
835 * The following is done on behalf of the newly created
836 * kthread. That kthread is responsible for doing the
837 * counterpart to the following before it exits.
839 if (ignore_disconnecting) {
840 if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
841 /* kthreads assigned had gone to zero */
843 XPC_C_DISCONNECTINGCALLOUT_MADE));
847 } else if (ch->flags & XPC_C_DISCONNECTING) {
850 } else if (atomic_inc_return(&ch->kthreads_assigned) == 1) {
851 if (atomic_inc_return(&part->nchannels_engaged) == 1)
852 xpc_mark_partition_engaged(part);
854 (void) xpc_part_ref(part);
855 xpc_msgqueue_ref(ch);
857 pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
859 /* the fork failed */
862 * NOTE: if (ignore_disconnecting &&
863 * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
864 * then we'll deadlock if all other kthreads assigned
865 * to this channel are blocked in the channel's
866 * registerer, because the only thing that will unblock
867 * them is the xpcDisconnecting callout that this
868 * failed kernel_thread would have made.
871 if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
872 atomic_dec_return(&part->nchannels_engaged) == 0) {
873 xpc_mark_partition_disengaged(part);
874 xpc_IPI_send_disengage(part);
876 xpc_msgqueue_deref(ch);
877 xpc_part_deref(part);
879 if (atomic_read(&ch->kthreads_assigned) <
880 ch->kthreads_idle_limit) {
882 * Flag this as an error only if we have an
883 * insufficient #of kthreads for the channel
886 spin_lock_irqsave(&ch->lock, irq_flags);
887 XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
889 spin_unlock_irqrestore(&ch->lock, irq_flags);
894 ch->kthreads_created++; // >>> temporary debug only!!!
900 xpc_disconnect_wait(int ch_number)
902 unsigned long irq_flags;
904 struct xpc_partition *part;
905 struct xpc_channel *ch;
906 int wakeup_channel_mgr;
909 /* now wait for all callouts to the caller's function to cease */
910 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
911 part = &xpc_partitions[partid];
913 if (!xpc_part_ref(part)) {
917 ch = &part->channels[ch_number];
919 if (!(ch->flags & XPC_C_WDISCONNECT)) {
920 xpc_part_deref(part);
924 wait_for_completion(&ch->wdisconnect_wait);
926 spin_lock_irqsave(&ch->lock, irq_flags);
927 DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
928 wakeup_channel_mgr = 0;
930 if (ch->delayed_IPI_flags) {
931 if (part->act_state != XPC_P_DEACTIVATING) {
932 spin_lock(&part->IPI_lock);
933 XPC_SET_IPI_FLAGS(part->local_IPI_amo,
934 ch->number, ch->delayed_IPI_flags);
935 spin_unlock(&part->IPI_lock);
936 wakeup_channel_mgr = 1;
938 ch->delayed_IPI_flags = 0;
941 ch->flags &= ~XPC_C_WDISCONNECT;
942 spin_unlock_irqrestore(&ch->lock, irq_flags);
944 if (wakeup_channel_mgr) {
945 xpc_wakeup_channel_mgr(part);
948 xpc_part_deref(part);
954 xpc_do_exit(enum xpc_retval reason)
957 int active_part_count, printed_waiting_msg = 0;
958 struct xpc_partition *part;
959 unsigned long printmsg_time, disengage_request_timeout = 0;
962 /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
963 DBUG_ON(xpc_exiting == 1);
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.
971 wake_up_interruptible(&xpc_act_IRQ_wq);
973 /* ignore all incoming interrupts */
974 free_irq(SGI_XPC_ACTIVATE, NULL);
976 /* wait for the discovery thread to exit */
977 wait_for_completion(&xpc_discovery_exited);
979 /* wait for the heartbeat checker thread to exit */
980 wait_for_completion(&xpc_hb_checker_exited);
983 /* sleep for a 1/3 of a second or so */
984 (void) msleep_interruptible(300);
987 /* wait for all partitions to become inactive */
989 printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
990 xpc_disengage_request_timedout = 0;
993 active_part_count = 0;
995 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
996 part = &xpc_partitions[partid];
998 if (xpc_partition_disengaged(part) &&
999 part->act_state == XPC_P_INACTIVE) {
1003 active_part_count++;
1005 XPC_DEACTIVATE_PARTITION(part, reason);
1007 if (part->disengage_request_timeout >
1008 disengage_request_timeout) {
1009 disengage_request_timeout =
1010 part->disengage_request_timeout;
1014 if (xpc_partition_engaged(-1UL)) {
1015 if (time_after(jiffies, printmsg_time)) {
1016 dev_info(xpc_part, "waiting for remote "
1017 "partitions to disengage, timeout in "
1019 (disengage_request_timeout - jiffies)
1021 printmsg_time = jiffies +
1022 (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
1023 printed_waiting_msg = 1;
1026 } else if (active_part_count > 0) {
1027 if (printed_waiting_msg) {
1028 dev_info(xpc_part, "waiting for local partition"
1030 printed_waiting_msg = 0;
1034 if (!xpc_disengage_request_timedout) {
1035 dev_info(xpc_part, "all partitions have "
1041 /* sleep for a 1/3 of a second or so */
1042 (void) msleep_interruptible(300);
1046 DBUG_ON(xpc_partition_engaged(-1UL));
1049 /* indicate to others that our reserved page is uninitialized */
1050 xpc_rsvd_page->vars_pa = 0;
1052 /* now it's time to eliminate our heartbeat */
1053 del_timer_sync(&xpc_hb_timer);
1054 DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
1056 if (reason == xpcUnloading) {
1057 /* take ourselves off of the reboot_notifier_list */
1058 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1060 /* take ourselves off of the die_notifier list */
1061 (void) unregister_die_notifier(&xpc_die_notifier);
1064 /* close down protections for IPI operations */
1065 xpc_restrict_IPI_ops();
1068 /* clear the interface to XPC's functions */
1069 xpc_clear_interface();
1072 unregister_sysctl_table(xpc_sysctl);
1075 kfree(xpc_remote_copy_buffer_base);
1080 * This function is called when the system is being rebooted.
1083 xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
1085 enum xpc_retval reason;
1090 reason = xpcSystemReboot;
1093 reason = xpcSystemHalt;
1096 reason = xpcSystemPoweroff;
1099 reason = xpcSystemGoingDown;
1102 xpc_do_exit(reason);
1108 * Notify other partitions to disengage from all references to our memory.
1111 xpc_die_disengage(void)
1113 struct xpc_partition *part;
1115 unsigned long engaged;
1116 long time, printmsg_time, disengage_request_timeout;
1119 /* keep xpc_hb_checker thread from doing anything (just in case) */
1122 xpc_vars->heartbeating_to_mask = 0; /* indicate we're deactivated */
1124 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1125 part = &xpc_partitions[partid];
1127 if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
1128 remote_vars_version)) {
1130 /* just in case it was left set by an earlier XPC */
1131 xpc_clear_partition_engaged(1UL << partid);
1135 if (xpc_partition_engaged(1UL << partid) ||
1136 part->act_state != XPC_P_INACTIVE) {
1137 xpc_request_partition_disengage(part);
1138 xpc_mark_partition_disengaged(part);
1139 xpc_IPI_send_disengage(part);
1144 printmsg_time = time +
1145 (XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
1146 disengage_request_timeout = time +
1147 (xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
1149 /* wait for all other partitions to disengage from us */
1152 engaged = xpc_partition_engaged(-1UL);
1154 dev_info(xpc_part, "all partitions have disengaged\n");
1159 if (time >= disengage_request_timeout) {
1160 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1161 if (engaged & (1UL << partid)) {
1162 dev_info(xpc_part, "disengage from "
1163 "remote partition %d timed "
1170 if (time >= printmsg_time) {
1171 dev_info(xpc_part, "waiting for remote partitions to "
1172 "disengage, timeout in %ld seconds\n",
1173 (disengage_request_timeout - time) /
1174 sn_rtc_cycles_per_second);
1175 printmsg_time = time +
1176 (XPC_DISENGAGE_PRINTMSG_INTERVAL *
1177 sn_rtc_cycles_per_second);
1184 * This function is called when the system is being restarted or halted due
1185 * to some sort of system failure. If this is the case we need to notify the
1186 * other partitions to disengage from all references to our memory.
1187 * This function can also be called when our heartbeater could be offlined
1188 * for a time. In this case we need to notify other partitions to not worry
1189 * about the lack of a heartbeat.
1192 xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
1195 case DIE_MACHINE_RESTART:
1196 case DIE_MACHINE_HALT:
1197 xpc_die_disengage();
1200 case DIE_KDEBUG_ENTER:
1201 /* Should lack of heartbeat be ignored by other partitions? */
1202 if (!xpc_kdebug_ignore) {
1206 case DIE_MCA_MONARCH_ENTER:
1207 case DIE_INIT_MONARCH_ENTER:
1208 xpc_vars->heartbeat++;
1209 xpc_vars->heartbeat_offline = 1;
1212 case DIE_KDEBUG_LEAVE:
1213 /* Is lack of heartbeat being ignored by other partitions? */
1214 if (!xpc_kdebug_ignore) {
1218 case DIE_MCA_MONARCH_LEAVE:
1219 case DIE_INIT_MONARCH_LEAVE:
1220 xpc_vars->heartbeat++;
1221 xpc_vars->heartbeat_offline = 0;
1234 struct xpc_partition *part;
1239 if (!ia64_platform_is("sn2")) {
1244 buf_size = max(XPC_RP_VARS_SIZE,
1245 XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES);
1246 xpc_remote_copy_buffer = xpc_kmalloc_cacheline_aligned(buf_size,
1247 GFP_KERNEL, &xpc_remote_copy_buffer_base);
1248 if (xpc_remote_copy_buffer == NULL)
1251 snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
1252 snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
1254 xpc_sysctl = register_sysctl_table(xpc_sys_dir, 1);
1257 * The first few fields of each entry of xpc_partitions[] need to
1258 * be initialized now so that calls to xpc_connect() and
1259 * xpc_disconnect() can be made prior to the activation of any remote
1260 * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
1261 * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
1262 * PARTITION HAS BEEN ACTIVATED.
1264 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
1265 part = &xpc_partitions[partid];
1267 DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
1269 part->act_IRQ_rcvd = 0;
1270 spin_lock_init(&part->act_lock);
1271 part->act_state = XPC_P_INACTIVE;
1272 XPC_SET_REASON(part, 0, 0);
1274 init_timer(&part->disengage_request_timer);
1275 part->disengage_request_timer.function =
1276 xpc_timeout_partition_disengage_request;
1277 part->disengage_request_timer.data = (unsigned long) part;
1279 part->setup_state = XPC_P_UNSET;
1280 init_waitqueue_head(&part->teardown_wq);
1281 atomic_set(&part->references, 0);
1285 * Open up protections for IPI operations (and AMO operations on
1286 * Shub 1.1 systems).
1288 xpc_allow_IPI_ops();
1291 * Interrupts being processed will increment this atomic variable and
1292 * awaken the heartbeat thread which will process the interrupts.
1294 atomic_set(&xpc_act_IRQ_rcvd, 0);
1297 * This is safe to do before the xpc_hb_checker thread has started
1298 * because the handler releases a wait queue. If an interrupt is
1299 * received before the thread is waiting, it will not go to sleep,
1300 * but rather immediately process the interrupt.
1302 ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
1305 dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
1306 "errno=%d\n", -ret);
1308 xpc_restrict_IPI_ops();
1311 unregister_sysctl_table(xpc_sysctl);
1314 kfree(xpc_remote_copy_buffer_base);
1319 * Fill the partition reserved page with the information needed by
1320 * other partitions to discover we are alive and establish initial
1323 xpc_rsvd_page = xpc_rsvd_page_init();
1324 if (xpc_rsvd_page == NULL) {
1325 dev_err(xpc_part, "could not setup our reserved page\n");
1327 free_irq(SGI_XPC_ACTIVATE, NULL);
1328 xpc_restrict_IPI_ops();
1331 unregister_sysctl_table(xpc_sysctl);
1334 kfree(xpc_remote_copy_buffer_base);
1339 /* add ourselves to the reboot_notifier_list */
1340 ret = register_reboot_notifier(&xpc_reboot_notifier);
1342 dev_warn(xpc_part, "can't register reboot notifier\n");
1345 /* add ourselves to the die_notifier list (i.e., ia64die_chain) */
1346 ret = register_die_notifier(&xpc_die_notifier);
1348 dev_warn(xpc_part, "can't register die notifier\n");
1353 * Set the beating to other partitions into motion. This is
1354 * the last requirement for other partitions' discovery to
1355 * initiate communications with us.
1357 init_timer(&xpc_hb_timer);
1358 xpc_hb_timer.function = xpc_hb_beater;
1363 * The real work-horse behind xpc. This processes incoming
1364 * interrupts and monitors remote heartbeats.
1366 pid = kernel_thread(xpc_hb_checker, NULL, 0);
1368 dev_err(xpc_part, "failed while forking hb check thread\n");
1370 /* indicate to others that our reserved page is uninitialized */
1371 xpc_rsvd_page->vars_pa = 0;
1373 /* take ourselves off of the reboot_notifier_list */
1374 (void) unregister_reboot_notifier(&xpc_reboot_notifier);
1376 /* take ourselves off of the die_notifier list */
1377 (void) unregister_die_notifier(&xpc_die_notifier);
1379 del_timer_sync(&xpc_hb_timer);
1380 free_irq(SGI_XPC_ACTIVATE, NULL);
1381 xpc_restrict_IPI_ops();
1384 unregister_sysctl_table(xpc_sysctl);
1387 kfree(xpc_remote_copy_buffer_base);
1393 * Startup a thread that will attempt to discover other partitions to
1394 * activate based on info provided by SAL. This new thread is short
1395 * lived and will exit once discovery is complete.
1397 pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
1399 dev_err(xpc_part, "failed while forking discovery thread\n");
1401 /* mark this new thread as a non-starter */
1402 complete(&xpc_discovery_exited);
1404 xpc_do_exit(xpcUnloading);
1409 /* set the interface to point at XPC's functions */
1410 xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
1411 xpc_initiate_allocate, xpc_initiate_send,
1412 xpc_initiate_send_notify, xpc_initiate_received,
1413 xpc_initiate_partid_to_nasids);
1417 module_init(xpc_init);
1423 xpc_do_exit(xpcUnloading);
1425 module_exit(xpc_exit);
1428 MODULE_AUTHOR("Silicon Graphics, Inc.");
1429 MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
1430 MODULE_LICENSE("GPL");
1432 module_param(xpc_hb_interval, int, 0);
1433 MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
1434 "heartbeat increments.");
1436 module_param(xpc_hb_check_interval, int, 0);
1437 MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
1438 "heartbeat checks.");
1440 module_param(xpc_disengage_request_timelimit, int, 0);
1441 MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
1442 "for disengage request to complete.");
1444 module_param(xpc_kdebug_ignore, int, 0);
1445 MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
1446 "other partitions when dropping into kdebug.");