diff options
Diffstat (limited to 'drivers/misc/sgi-xp/xpc_main.c')
| -rw-r--r-- | drivers/misc/sgi-xp/xpc_main.c | 1349 |
1 files changed, 1349 insertions, 0 deletions
diff --git a/drivers/misc/sgi-xp/xpc_main.c b/drivers/misc/sgi-xp/xpc_main.c new file mode 100644 index 000000000..b2c3c22fc --- /dev/null +++ b/drivers/misc/sgi-xp/xpc_main.c @@ -0,0 +1,1349 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * (C) Copyright 2020 Hewlett Packard Enterprise Development LP + * Copyright (c) 2004-2009 Silicon Graphics, Inc. All Rights Reserved. + */ + +/* + * Cross Partition Communication (XPC) support - standard version. + * + * XPC provides a message passing capability that crosses partition + * boundaries. This module is made up of two parts: + * + * partition This part detects the presence/absence of other + * partitions. It provides a heartbeat and monitors + * the heartbeats of other partitions. + * + * channel This part manages the channels and sends/receives + * messages across them to/from other partitions. + * + * There are a couple of additional functions residing in XP, which + * provide an interface to XPC for its users. + * + * + * Caveats: + * + * . Currently on sn2, we have no way to determine which nasid an IRQ + * came from. Thus, xpc_send_IRQ_sn2() does a remote amo write + * followed by an IPI. The amo indicates where data is to be pulled + * from, so after the IPI arrives, the remote partition checks the amo + * word. The IPI can actually arrive before the amo however, so other + * code must periodically check for this case. Also, remote amo + * operations do not reliably time out. Thus we do a remote PIO read + * solely to know whether the remote partition is down and whether we + * should stop sending IPIs to it. This remote PIO read operation is + * set up in a special nofault region so SAL knows to ignore (and + * cleanup) any errors due to the remote amo write, PIO read, and/or + * PIO write operations. + * + * If/when new hardware solves this IPI problem, we should abandon + * the current approach. + * + */ + +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/sysctl.h> +#include <linux/device.h> +#include <linux/delay.h> +#include <linux/reboot.h> +#include <linux/kdebug.h> +#include <linux/kthread.h> +#include "xpc.h" + +#ifdef CONFIG_X86_64 +#include <asm/traps.h> +#endif + +/* define two XPC debug device structures to be used with dev_dbg() et al */ + +static struct device_driver xpc_dbg_name = { + .name = "xpc" +}; + +static struct device xpc_part_dbg_subname = { + .init_name = "", /* set to "part" at xpc_init() time */ + .driver = &xpc_dbg_name +}; + +static struct device xpc_chan_dbg_subname = { + .init_name = "", /* set to "chan" at xpc_init() time */ + .driver = &xpc_dbg_name +}; + +struct device *xpc_part = &xpc_part_dbg_subname; +struct device *xpc_chan = &xpc_chan_dbg_subname; + +static int xpc_kdebug_ignore; + +/* systune related variables for /proc/sys directories */ + +static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL; +static int xpc_hb_min_interval = 1; +static int xpc_hb_max_interval = 10; + +static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL; +static int xpc_hb_check_min_interval = 10; +static int xpc_hb_check_max_interval = 120; + +int xpc_disengage_timelimit = XPC_DISENGAGE_DEFAULT_TIMELIMIT; +static int xpc_disengage_min_timelimit; /* = 0 */ +static int xpc_disengage_max_timelimit = 120; + +static struct ctl_table xpc_sys_xpc_hb_dir[] = { + { + .procname = "hb_interval", + .data = &xpc_hb_interval, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &xpc_hb_min_interval, + .extra2 = &xpc_hb_max_interval}, + { + .procname = "hb_check_interval", + .data = &xpc_hb_check_interval, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &xpc_hb_check_min_interval, + .extra2 = &xpc_hb_check_max_interval}, + {} +}; +static struct ctl_table xpc_sys_xpc_dir[] = { + { + .procname = "hb", + .mode = 0555, + .child = xpc_sys_xpc_hb_dir}, + { + .procname = "disengage_timelimit", + .data = &xpc_disengage_timelimit, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &xpc_disengage_min_timelimit, + .extra2 = &xpc_disengage_max_timelimit}, + {} +}; +static struct ctl_table xpc_sys_dir[] = { + { + .procname = "xpc", + .mode = 0555, + .child = xpc_sys_xpc_dir}, + {} +}; +static struct ctl_table_header *xpc_sysctl; + +/* non-zero if any remote partition disengage was timed out */ +int xpc_disengage_timedout; + +/* #of activate IRQs received and not yet processed */ +int xpc_activate_IRQ_rcvd; +DEFINE_SPINLOCK(xpc_activate_IRQ_rcvd_lock); + +/* IRQ handler notifies this wait queue on receipt of an IRQ */ +DECLARE_WAIT_QUEUE_HEAD(xpc_activate_IRQ_wq); + +static unsigned long xpc_hb_check_timeout; +static struct timer_list xpc_hb_timer; + +/* notification that the xpc_hb_checker thread has exited */ +static DECLARE_COMPLETION(xpc_hb_checker_exited); + +/* notification that the xpc_discovery thread has exited */ +static DECLARE_COMPLETION(xpc_discovery_exited); + +static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *); + +static int xpc_system_reboot(struct notifier_block *, unsigned long, void *); +static struct notifier_block xpc_reboot_notifier = { + .notifier_call = xpc_system_reboot, +}; + +static int xpc_system_die(struct notifier_block *, unsigned long, void *); +static struct notifier_block xpc_die_notifier = { + .notifier_call = xpc_system_die, +}; + +struct xpc_arch_operations xpc_arch_ops; + +/* + * Timer function to enforce the timelimit on the partition disengage. + */ +static void +xpc_timeout_partition_disengage(struct timer_list *t) +{ + struct xpc_partition *part = from_timer(part, t, disengage_timer); + + DBUG_ON(time_is_after_jiffies(part->disengage_timeout)); + + xpc_partition_disengaged_from_timer(part); + + DBUG_ON(part->disengage_timeout != 0); + DBUG_ON(xpc_arch_ops.partition_engaged(XPC_PARTID(part))); +} + +/* + * Timer to produce the heartbeat. The timer structures function is + * already set when this is initially called. A tunable is used to + * specify when the next timeout should occur. + */ +static void +xpc_hb_beater(struct timer_list *unused) +{ + xpc_arch_ops.increment_heartbeat(); + + if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) + wake_up_interruptible(&xpc_activate_IRQ_wq); + + xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ); + add_timer(&xpc_hb_timer); +} + +static void +xpc_start_hb_beater(void) +{ + xpc_arch_ops.heartbeat_init(); + timer_setup(&xpc_hb_timer, xpc_hb_beater, 0); + xpc_hb_beater(NULL); +} + +static void +xpc_stop_hb_beater(void) +{ + del_timer_sync(&xpc_hb_timer); + xpc_arch_ops.heartbeat_exit(); +} + +/* + * At periodic intervals, scan through all active partitions and ensure + * their heartbeat is still active. If not, the partition is deactivated. + */ +static void +xpc_check_remote_hb(void) +{ + struct xpc_partition *part; + short partid; + enum xp_retval ret; + + for (partid = 0; partid < xp_max_npartitions; partid++) { + + if (xpc_exiting) + break; + + if (partid == xp_partition_id) + continue; + + part = &xpc_partitions[partid]; + + if (part->act_state == XPC_P_AS_INACTIVE || + part->act_state == XPC_P_AS_DEACTIVATING) { + continue; + } + + ret = xpc_arch_ops.get_remote_heartbeat(part); + if (ret != xpSuccess) + XPC_DEACTIVATE_PARTITION(part, ret); + } +} + +/* + * This thread is responsible for nearly all of the partition + * activation/deactivation. + */ +static int +xpc_hb_checker(void *ignore) +{ + int force_IRQ = 0; + + /* this thread was marked active by xpc_hb_init() */ + + set_cpus_allowed_ptr(current, cpumask_of(XPC_HB_CHECK_CPU)); + + /* set our heartbeating to other partitions into motion */ + xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ); + xpc_start_hb_beater(); + + while (!xpc_exiting) { + + dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have " + "been received\n", + (int)(xpc_hb_check_timeout - jiffies), + xpc_activate_IRQ_rcvd); + + /* checking of remote heartbeats is skewed by IRQ handling */ + if (time_is_before_eq_jiffies(xpc_hb_check_timeout)) { + xpc_hb_check_timeout = jiffies + + (xpc_hb_check_interval * HZ); + + dev_dbg(xpc_part, "checking remote heartbeats\n"); + xpc_check_remote_hb(); + } + + /* check for outstanding IRQs */ + if (xpc_activate_IRQ_rcvd > 0 || force_IRQ != 0) { + force_IRQ = 0; + dev_dbg(xpc_part, "processing activate IRQs " + "received\n"); + xpc_arch_ops.process_activate_IRQ_rcvd(); + } + + /* wait for IRQ or timeout */ + (void)wait_event_interruptible(xpc_activate_IRQ_wq, + (time_is_before_eq_jiffies( + xpc_hb_check_timeout) || + xpc_activate_IRQ_rcvd > 0 || + xpc_exiting)); + } + + xpc_stop_hb_beater(); + + dev_dbg(xpc_part, "heartbeat checker is exiting\n"); + + /* mark this thread as having exited */ + complete(&xpc_hb_checker_exited); + return 0; +} + +/* + * This thread will attempt to discover other partitions to activate + * based on info provided by SAL. This new thread is short lived and + * will exit once discovery is complete. + */ +static int +xpc_initiate_discovery(void *ignore) +{ + xpc_discovery(); + + dev_dbg(xpc_part, "discovery thread is exiting\n"); + + /* mark this thread as having exited */ + complete(&xpc_discovery_exited); + return 0; +} + +/* + * The first kthread assigned to a newly activated partition is the one + * created by XPC HB with which it calls xpc_activating(). XPC hangs on to + * that kthread until the partition is brought down, at which time that kthread + * returns back to XPC HB. (The return of that kthread will signify to XPC HB + * that XPC has dismantled all communication infrastructure for the associated + * partition.) This kthread becomes the channel manager for that partition. + * + * Each active partition has a channel manager, who, besides connecting and + * disconnecting channels, will ensure that each of the partition's connected + * channels has the required number of assigned kthreads to get the work done. + */ +static void +xpc_channel_mgr(struct xpc_partition *part) +{ + while (part->act_state != XPC_P_AS_DEACTIVATING || + atomic_read(&part->nchannels_active) > 0 || + !xpc_partition_disengaged(part)) { + + xpc_process_sent_chctl_flags(part); + + /* + * Wait until we've been requested to activate kthreads or + * all of the channel's message queues have been torn down or + * a signal is pending. + * + * The channel_mgr_requests is set to 1 after being awakened, + * This is done to prevent the channel mgr from making one pass + * through the loop for each request, since he will + * be servicing all the requests in one pass. The reason it's + * set to 1 instead of 0 is so that other kthreads will know + * that the channel mgr is running and won't bother trying to + * wake him up. + */ + atomic_dec(&part->channel_mgr_requests); + (void)wait_event_interruptible(part->channel_mgr_wq, + (atomic_read(&part->channel_mgr_requests) > 0 || + part->chctl.all_flags != 0 || + (part->act_state == XPC_P_AS_DEACTIVATING && + atomic_read(&part->nchannels_active) == 0 && + xpc_partition_disengaged(part)))); + atomic_set(&part->channel_mgr_requests, 1); + } +} + +/* + * Guarantee that the kzalloc'd memory is cacheline aligned. + */ +void * +xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base) +{ + /* see if kzalloc will give us cachline aligned memory by default */ + *base = kzalloc(size, flags); + if (*base == NULL) + return NULL; + + if ((u64)*base == L1_CACHE_ALIGN((u64)*base)) + return *base; + + kfree(*base); + + /* nope, we'll have to do it ourselves */ + *base = kzalloc(size + L1_CACHE_BYTES, flags); + if (*base == NULL) + return NULL; + + return (void *)L1_CACHE_ALIGN((u64)*base); +} + +/* + * Setup the channel structures necessary to support XPartition Communication + * between the specified remote partition and the local one. + */ +static enum xp_retval +xpc_setup_ch_structures(struct xpc_partition *part) +{ + enum xp_retval ret; + int ch_number; + struct xpc_channel *ch; + short partid = XPC_PARTID(part); + + /* + * Allocate all of the channel structures as a contiguous chunk of + * memory. + */ + DBUG_ON(part->channels != NULL); + part->channels = kcalloc(XPC_MAX_NCHANNELS, + sizeof(struct xpc_channel), + GFP_KERNEL); + if (part->channels == NULL) { + dev_err(xpc_chan, "can't get memory for channels\n"); + return xpNoMemory; + } + + /* allocate the remote open and close args */ + + part->remote_openclose_args = + xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE, + GFP_KERNEL, &part-> + remote_openclose_args_base); + if (part->remote_openclose_args == NULL) { + dev_err(xpc_chan, "can't get memory for remote connect args\n"); + ret = xpNoMemory; + goto out_1; + } + + part->chctl.all_flags = 0; + spin_lock_init(&part->chctl_lock); + + atomic_set(&part->channel_mgr_requests, 1); + init_waitqueue_head(&part->channel_mgr_wq); + + part->nchannels = XPC_MAX_NCHANNELS; + + atomic_set(&part->nchannels_active, 0); + atomic_set(&part->nchannels_engaged, 0); + + for (ch_number = 0; ch_number < part->nchannels; ch_number++) { + ch = &part->channels[ch_number]; + + ch->partid = partid; + ch->number = ch_number; + ch->flags = XPC_C_DISCONNECTED; + + atomic_set(&ch->kthreads_assigned, 0); + atomic_set(&ch->kthreads_idle, 0); + atomic_set(&ch->kthreads_active, 0); + + atomic_set(&ch->references, 0); + atomic_set(&ch->n_to_notify, 0); + + spin_lock_init(&ch->lock); + init_completion(&ch->wdisconnect_wait); + + atomic_set(&ch->n_on_msg_allocate_wq, 0); + init_waitqueue_head(&ch->msg_allocate_wq); + init_waitqueue_head(&ch->idle_wq); + } + + ret = xpc_arch_ops.setup_ch_structures(part); + if (ret != xpSuccess) + goto out_2; + + /* + * With the setting of the partition setup_state to XPC_P_SS_SETUP, + * we're declaring that this partition is ready to go. + */ + part->setup_state = XPC_P_SS_SETUP; + + return xpSuccess; + + /* setup of ch structures failed */ +out_2: + kfree(part->remote_openclose_args_base); + part->remote_openclose_args = NULL; +out_1: + kfree(part->channels); + part->channels = NULL; + return ret; +} + +/* + * Teardown the channel structures necessary to support XPartition Communication + * between the specified remote partition and the local one. + */ +static void +xpc_teardown_ch_structures(struct xpc_partition *part) +{ + DBUG_ON(atomic_read(&part->nchannels_engaged) != 0); + DBUG_ON(atomic_read(&part->nchannels_active) != 0); + + /* + * Make this partition inaccessible to local processes by marking it + * as no longer setup. Then wait before proceeding with the teardown + * until all existing references cease. + */ + DBUG_ON(part->setup_state != XPC_P_SS_SETUP); + part->setup_state = XPC_P_SS_WTEARDOWN; + + wait_event(part->teardown_wq, (atomic_read(&part->references) == 0)); + + /* now we can begin tearing down the infrastructure */ + + xpc_arch_ops.teardown_ch_structures(part); + + kfree(part->remote_openclose_args_base); + part->remote_openclose_args = NULL; + kfree(part->channels); + part->channels = NULL; + + part->setup_state = XPC_P_SS_TORNDOWN; +} + +/* + * When XPC HB determines that a partition has come up, it will create a new + * kthread and that kthread will call this function to attempt to set up the + * basic infrastructure used for Cross Partition Communication with the newly + * upped partition. + * + * The kthread that was created by XPC HB and which setup the XPC + * infrastructure will remain assigned to the partition becoming the channel + * manager for that partition until the partition is deactivating, at which + * time the kthread will teardown the XPC infrastructure and then exit. + */ +static int +xpc_activating(void *__partid) +{ + short partid = (u64)__partid; + struct xpc_partition *part = &xpc_partitions[partid]; + unsigned long irq_flags; + + DBUG_ON(partid < 0 || partid >= xp_max_npartitions); + + spin_lock_irqsave(&part->act_lock, irq_flags); + + if (part->act_state == XPC_P_AS_DEACTIVATING) { + part->act_state = XPC_P_AS_INACTIVE; + spin_unlock_irqrestore(&part->act_lock, irq_flags); + part->remote_rp_pa = 0; + return 0; + } + + /* indicate the thread is activating */ + DBUG_ON(part->act_state != XPC_P_AS_ACTIVATION_REQ); + part->act_state = XPC_P_AS_ACTIVATING; + + XPC_SET_REASON(part, 0, 0); + spin_unlock_irqrestore(&part->act_lock, irq_flags); + + dev_dbg(xpc_part, "activating partition %d\n", partid); + + xpc_arch_ops.allow_hb(partid); + + if (xpc_setup_ch_structures(part) == xpSuccess) { + (void)xpc_part_ref(part); /* this will always succeed */ + + if (xpc_arch_ops.make_first_contact(part) == xpSuccess) { + xpc_mark_partition_active(part); + xpc_channel_mgr(part); + /* won't return until partition is deactivating */ + } + + xpc_part_deref(part); + xpc_teardown_ch_structures(part); + } + + xpc_arch_ops.disallow_hb(partid); + xpc_mark_partition_inactive(part); + + if (part->reason == xpReactivating) { + /* interrupting ourselves results in activating partition */ + xpc_arch_ops.request_partition_reactivation(part); + } + + return 0; +} + +void +xpc_activate_partition(struct xpc_partition *part) +{ + short partid = XPC_PARTID(part); + unsigned long irq_flags; + struct task_struct *kthread; + + spin_lock_irqsave(&part->act_lock, irq_flags); + + DBUG_ON(part->act_state != XPC_P_AS_INACTIVE); + + part->act_state = XPC_P_AS_ACTIVATION_REQ; + XPC_SET_REASON(part, xpCloneKThread, __LINE__); + + spin_unlock_irqrestore(&part->act_lock, irq_flags); + + kthread = kthread_run(xpc_activating, (void *)((u64)partid), "xpc%02d", + partid); + if (IS_ERR(kthread)) { + spin_lock_irqsave(&part->act_lock, irq_flags); + part->act_state = XPC_P_AS_INACTIVE; + XPC_SET_REASON(part, xpCloneKThreadFailed, __LINE__); + spin_unlock_irqrestore(&part->act_lock, irq_flags); + } +} + +void +xpc_activate_kthreads(struct xpc_channel *ch, int needed) +{ + int idle = atomic_read(&ch->kthreads_idle); + int assigned = atomic_read(&ch->kthreads_assigned); + int wakeup; + + DBUG_ON(needed <= 0); + + if (idle > 0) { + wakeup = (needed > idle) ? idle : needed; + needed -= wakeup; + + dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, " + "channel=%d\n", wakeup, ch->partid, ch->number); + + /* only wakeup the requested number of kthreads */ + wake_up_nr(&ch->idle_wq, wakeup); + } + + if (needed <= 0) + return; + + if (needed + assigned > ch->kthreads_assigned_limit) { + needed = ch->kthreads_assigned_limit - assigned; + if (needed <= 0) + return; + } + + dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n", + needed, ch->partid, ch->number); + + xpc_create_kthreads(ch, needed, 0); +} + +/* + * This function is where XPC's kthreads wait for messages to deliver. + */ +static void +xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch) +{ + int (*n_of_deliverable_payloads) (struct xpc_channel *) = + xpc_arch_ops.n_of_deliverable_payloads; + + do { + /* deliver messages to their intended recipients */ + + while (n_of_deliverable_payloads(ch) > 0 && + !(ch->flags & XPC_C_DISCONNECTING)) { + xpc_deliver_payload(ch); + } + + if (atomic_inc_return(&ch->kthreads_idle) > + ch->kthreads_idle_limit) { + /* too many idle kthreads on this channel */ + atomic_dec(&ch->kthreads_idle); + break; + } + + dev_dbg(xpc_chan, "idle kthread calling " + "wait_event_interruptible_exclusive()\n"); + + (void)wait_event_interruptible_exclusive(ch->idle_wq, + (n_of_deliverable_payloads(ch) > 0 || + (ch->flags & XPC_C_DISCONNECTING))); + + atomic_dec(&ch->kthreads_idle); + + } while (!(ch->flags & XPC_C_DISCONNECTING)); +} + +static int +xpc_kthread_start(void *args) +{ + short partid = XPC_UNPACK_ARG1(args); + u16 ch_number = XPC_UNPACK_ARG2(args); + struct xpc_partition *part = &xpc_partitions[partid]; + struct xpc_channel *ch; + int n_needed; + unsigned long irq_flags; + int (*n_of_deliverable_payloads) (struct xpc_channel *) = + xpc_arch_ops.n_of_deliverable_payloads; + + dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n", + partid, ch_number); + + ch = &part->channels[ch_number]; + + if (!(ch->flags & XPC_C_DISCONNECTING)) { + + /* let registerer know that connection has been established */ + + spin_lock_irqsave(&ch->lock, irq_flags); + if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) { + ch->flags |= XPC_C_CONNECTEDCALLOUT; + spin_unlock_irqrestore(&ch->lock, irq_flags); + + xpc_connected_callout(ch); + + spin_lock_irqsave(&ch->lock, irq_flags); + ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE; + spin_unlock_irqrestore(&ch->lock, irq_flags); + + /* + * It is possible that while the callout was being + * made that the remote partition sent some messages. + * If that is the case, we may need to activate + * additional kthreads to help deliver them. We only + * need one less than total #of messages to deliver. + */ + n_needed = n_of_deliverable_payloads(ch) - 1; + if (n_needed > 0 && !(ch->flags & XPC_C_DISCONNECTING)) + xpc_activate_kthreads(ch, n_needed); + + } else { + spin_unlock_irqrestore(&ch->lock, irq_flags); + } + + xpc_kthread_waitmsgs(part, ch); + } + + /* let registerer know that connection is disconnecting */ + + spin_lock_irqsave(&ch->lock, irq_flags); + if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) && + !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) { + ch->flags |= XPC_C_DISCONNECTINGCALLOUT; + spin_unlock_irqrestore(&ch->lock, irq_flags); + + xpc_disconnect_callout(ch, xpDisconnecting); + + spin_lock_irqsave(&ch->lock, irq_flags); + ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE; + } + spin_unlock_irqrestore(&ch->lock, irq_flags); + + if (atomic_dec_return(&ch->kthreads_assigned) == 0 && + atomic_dec_return(&part->nchannels_engaged) == 0) { + xpc_arch_ops.indicate_partition_disengaged(part); + } + + xpc_msgqueue_deref(ch); + + dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n", + partid, ch_number); + + xpc_part_deref(part); + return 0; +} + +/* + * For each partition that XPC has established communications with, there is + * a minimum of one kernel thread assigned to perform any operation that + * may potentially sleep or block (basically the callouts to the asynchronous + * functions registered via xpc_connect()). + * + * Additional kthreads are created and destroyed by XPC as the workload + * demands. + * + * A kthread is assigned to one of the active channels that exists for a given + * partition. + */ +void +xpc_create_kthreads(struct xpc_channel *ch, int needed, + int ignore_disconnecting) +{ + unsigned long irq_flags; + u64 args = XPC_PACK_ARGS(ch->partid, ch->number); + struct xpc_partition *part = &xpc_partitions[ch->partid]; + struct task_struct *kthread; + void (*indicate_partition_disengaged) (struct xpc_partition *) = + xpc_arch_ops.indicate_partition_disengaged; + + while (needed-- > 0) { + + /* + * The following is done on behalf of the newly created + * kthread. That kthread is responsible for doing the + * counterpart to the following before it exits. + */ + if (ignore_disconnecting) { + if (!atomic_inc_not_zero(&ch->kthreads_assigned)) { + /* kthreads assigned had gone to zero */ + BUG_ON(!(ch->flags & + XPC_C_DISCONNECTINGCALLOUT_MADE)); + break; + } + + } else if (ch->flags & XPC_C_DISCONNECTING) { + break; + + } else if (atomic_inc_return(&ch->kthreads_assigned) == 1 && + atomic_inc_return(&part->nchannels_engaged) == 1) { + xpc_arch_ops.indicate_partition_engaged(part); + } + (void)xpc_part_ref(part); + xpc_msgqueue_ref(ch); + + kthread = kthread_run(xpc_kthread_start, (void *)args, + "xpc%02dc%d", ch->partid, ch->number); + if (IS_ERR(kthread)) { + /* the fork failed */ + + /* + * NOTE: if (ignore_disconnecting && + * !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true, + * then we'll deadlock if all other kthreads assigned + * to this channel are blocked in the channel's + * registerer, because the only thing that will unblock + * them is the xpDisconnecting callout that this + * failed kthread_run() would have made. + */ + + if (atomic_dec_return(&ch->kthreads_assigned) == 0 && + atomic_dec_return(&part->nchannels_engaged) == 0) { + indicate_partition_disengaged(part); + } + xpc_msgqueue_deref(ch); + xpc_part_deref(part); + + if (atomic_read(&ch->kthreads_assigned) < + ch->kthreads_idle_limit) { + /* + * Flag this as an error only if we have an + * insufficient #of kthreads for the channel + * to function. + */ + spin_lock_irqsave(&ch->lock, irq_flags); + XPC_DISCONNECT_CHANNEL(ch, xpLackOfResources, + &irq_flags); + spin_unlock_irqrestore(&ch->lock, irq_flags); + } + break; + } + } +} + +void +xpc_disconnect_wait(int ch_number) +{ + unsigned long irq_flags; + short partid; + struct xpc_partition *part; + struct xpc_channel *ch; + int wakeup_channel_mgr; + + /* now wait for all callouts to the caller's function to cease */ + for (partid = 0; partid < xp_max_npartitions; partid++) { + part = &xpc_partitions[partid]; + + if (!xpc_part_ref(part)) + continue; + + ch = &part->channels[ch_number]; + + if (!(ch->flags & XPC_C_WDISCONNECT)) { + xpc_part_deref(part); + continue; + } + + wait_for_completion(&ch->wdisconnect_wait); + + spin_lock_irqsave(&ch->lock, irq_flags); + DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED)); + wakeup_channel_mgr = 0; + + if (ch->delayed_chctl_flags) { + if (part->act_state != XPC_P_AS_DEACTIVATING) { + spin_lock(&part->chctl_lock); + part->chctl.flags[ch->number] |= + ch->delayed_chctl_flags; + spin_unlock(&part->chctl_lock); + wakeup_channel_mgr = 1; + } + ch->delayed_chctl_flags = 0; + } + + ch->flags &= ~XPC_C_WDISCONNECT; + spin_unlock_irqrestore(&ch->lock, irq_flags); + + if (wakeup_channel_mgr) + xpc_wakeup_channel_mgr(part); + + xpc_part_deref(part); + } +} + +static int +xpc_setup_partitions(void) +{ + short partid; + struct xpc_partition *part; + + xpc_partitions = kcalloc(xp_max_npartitions, + sizeof(struct xpc_partition), + GFP_KERNEL); + if (xpc_partitions == NULL) { + dev_err(xpc_part, "can't get memory for partition structure\n"); + return -ENOMEM; + } + + /* + * The first few fields of each entry of xpc_partitions[] need to + * be initialized now so that calls to xpc_connect() and + * xpc_disconnect() can be made prior to the activation of any remote + * partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE + * ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING + * PARTITION HAS BEEN ACTIVATED. + */ + for (partid = 0; partid < xp_max_npartitions; partid++) { + part = &xpc_partitions[partid]; + + DBUG_ON((u64)part != L1_CACHE_ALIGN((u64)part)); + + part->activate_IRQ_rcvd = 0; + spin_lock_init(&part->act_lock); + part->act_state = XPC_P_AS_INACTIVE; + XPC_SET_REASON(part, 0, 0); + + timer_setup(&part->disengage_timer, + xpc_timeout_partition_disengage, 0); + + part->setup_state = XPC_P_SS_UNSET; + init_waitqueue_head(&part->teardown_wq); + atomic_set(&part->references, 0); + } + + return xpc_arch_ops.setup_partitions(); +} + +static void +xpc_teardown_partitions(void) +{ + xpc_arch_ops.teardown_partitions(); + kfree(xpc_partitions); +} + +static void +xpc_do_exit(enum xp_retval reason) +{ + short partid; + int active_part_count, printed_waiting_msg = 0; + struct xpc_partition *part; + unsigned long printmsg_time, disengage_timeout = 0; + + /* a 'rmmod XPC' and a 'reboot' cannot both end up here together */ + DBUG_ON(xpc_exiting == 1); + + /* + * Let the heartbeat checker thread and the discovery thread + * (if one is running) know that they should exit. Also wake up + * the heartbeat checker thread in case it's sleeping. + */ + xpc_exiting = 1; + wake_up_interruptible(&xpc_activate_IRQ_wq); + + /* wait for the discovery thread to exit */ + wait_for_completion(&xpc_discovery_exited); + + /* wait for the heartbeat checker thread to exit */ + wait_for_completion(&xpc_hb_checker_exited); + + /* sleep for a 1/3 of a second or so */ + (void)msleep_interruptible(300); + + /* wait for all partitions to become inactive */ + + printmsg_time = jiffies + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ); + xpc_disengage_timedout = 0; + + do { + active_part_count = 0; + + for (partid = 0; partid < xp_max_npartitions; partid++) { + part = &xpc_partitions[partid]; + + if (xpc_partition_disengaged(part) && + part->act_state == XPC_P_AS_INACTIVE) { + continue; + } + + active_part_count++; + + XPC_DEACTIVATE_PARTITION(part, reason); + + if (part->disengage_timeout > disengage_timeout) + disengage_timeout = part->disengage_timeout; + } + + if (xpc_arch_ops.any_partition_engaged()) { + if (time_is_before_jiffies(printmsg_time)) { + dev_info(xpc_part, "waiting for remote " + "partitions to deactivate, timeout in " + "%ld seconds\n", (disengage_timeout - + jiffies) / HZ); + printmsg_time = jiffies + + (XPC_DEACTIVATE_PRINTMSG_INTERVAL * HZ); + printed_waiting_msg = 1; + } + + } else if (active_part_count > 0) { + if (printed_waiting_msg) { + dev_info(xpc_part, "waiting for local partition" + " to deactivate\n"); + printed_waiting_msg = 0; + } + + } else { + if (!xpc_disengage_timedout) { + dev_info(xpc_part, "all partitions have " + "deactivated\n"); + } + break; + } + + /* sleep for a 1/3 of a second or so */ + (void)msleep_interruptible(300); + + } while (1); + + DBUG_ON(xpc_arch_ops.any_partition_engaged()); + + xpc_teardown_rsvd_page(); + + if (reason == xpUnloading) { + (void)unregister_die_notifier(&xpc_die_notifier); + (void)unregister_reboot_notifier(&xpc_reboot_notifier); + } + + /* clear the interface to XPC's functions */ + xpc_clear_interface(); + + if (xpc_sysctl) + unregister_sysctl_table(xpc_sysctl); + + xpc_teardown_partitions(); + + if (is_uv_system()) + xpc_exit_uv(); +} + +/* + * This function is called when the system is being rebooted. + */ +static int +xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused) +{ + enum xp_retval reason; + + switch (event) { + case SYS_RESTART: + reason = xpSystemReboot; + break; + case SYS_HALT: + reason = xpSystemHalt; + break; + case SYS_POWER_OFF: + reason = xpSystemPoweroff; + break; + default: + reason = xpSystemGoingDown; + } + + xpc_do_exit(reason); + return NOTIFY_DONE; +} + +/* Used to only allow one cpu to complete disconnect */ +static unsigned int xpc_die_disconnecting; + +/* + * Notify other partitions to deactivate from us by first disengaging from all + * references to our memory. + */ +static void +xpc_die_deactivate(void) +{ + struct xpc_partition *part; + short partid; + int any_engaged; + long keep_waiting; + long wait_to_print; + + if (cmpxchg(&xpc_die_disconnecting, 0, 1)) + return; + + /* keep xpc_hb_checker thread from doing anything (just in case) */ + xpc_exiting = 1; + + xpc_arch_ops.disallow_all_hbs(); /*indicate we're deactivated */ + + for (partid = 0; partid < xp_max_npartitions; partid++) { + part = &xpc_partitions[partid]; + + if (xpc_arch_ops.partition_engaged(partid) || + part->act_state != XPC_P_AS_INACTIVE) { + xpc_arch_ops.request_partition_deactivation(part); + xpc_arch_ops.indicate_partition_disengaged(part); + } + } + + /* + * Though we requested that all other partitions deactivate from us, + * we only wait until they've all disengaged or we've reached the + * defined timelimit. + * + * Given that one iteration through the following while-loop takes + * approximately 200 microseconds, calculate the #of loops to take + * before bailing and the #of loops before printing a waiting message. + */ + keep_waiting = xpc_disengage_timelimit * 1000 * 5; + wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * 1000 * 5; + + while (1) { + any_engaged = xpc_arch_ops.any_partition_engaged(); + if (!any_engaged) { + dev_info(xpc_part, "all partitions have deactivated\n"); + break; + } + + if (!keep_waiting--) { + for (partid = 0; partid < xp_max_npartitions; + partid++) { + if (xpc_arch_ops.partition_engaged(partid)) { + dev_info(xpc_part, "deactivate from " + "remote partition %d timed " + "out\n", partid); + } + } + break; + } + + if (!wait_to_print--) { + dev_info(xpc_part, "waiting for remote partitions to " + "deactivate, timeout in %ld seconds\n", + keep_waiting / (1000 * 5)); + wait_to_print = XPC_DEACTIVATE_PRINTMSG_INTERVAL * + 1000 * 5; + } + + udelay(200); + } +} + +/* + * This function is called when the system is being restarted or halted due + * to some sort of system failure. If this is the case we need to notify the + * other partitions to disengage from all references to our memory. + * This function can also be called when our heartbeater could be offlined + * for a time. In this case we need to notify other partitions to not worry + * about the lack of a heartbeat. + */ +static int +xpc_system_die(struct notifier_block *nb, unsigned long event, void *_die_args) +{ +#ifdef CONFIG_IA64 /* !!! temporary kludge */ + switch (event) { + case DIE_MACHINE_RESTART: + case DIE_MACHINE_HALT: + xpc_die_deactivate(); + break; + + case DIE_KDEBUG_ENTER: + /* Should lack of heartbeat be ignored by other partitions? */ + if (!xpc_kdebug_ignore) + break; + + fallthrough; + case DIE_MCA_MONARCH_ENTER: + case DIE_INIT_MONARCH_ENTER: + xpc_arch_ops.offline_heartbeat(); + break; + + case DIE_KDEBUG_LEAVE: + /* Is lack of heartbeat being ignored by other partitions? */ + if (!xpc_kdebug_ignore) + break; + + fallthrough; + case DIE_MCA_MONARCH_LEAVE: + case DIE_INIT_MONARCH_LEAVE: + xpc_arch_ops.online_heartbeat(); + break; + } +#else + struct die_args *die_args = _die_args; + + switch (event) { + case DIE_TRAP: + if (die_args->trapnr == X86_TRAP_DF) + xpc_die_deactivate(); + + if (((die_args->trapnr == X86_TRAP_MF) || + (die_args->trapnr == X86_TRAP_XF)) && + !user_mode(die_args->regs)) + xpc_die_deactivate(); + + break; + case DIE_INT3: + case DIE_DEBUG: + break; + case DIE_OOPS: + case DIE_GPF: + default: + xpc_die_deactivate(); + } +#endif + + return NOTIFY_DONE; +} + +static int __init +xpc_init(void) +{ + int ret; + struct task_struct *kthread; + + dev_set_name(xpc_part, "part"); + dev_set_name(xpc_chan, "chan"); + + if (is_uv_system()) { + ret = xpc_init_uv(); + + } else { + ret = -ENODEV; + } + + if (ret != 0) + return ret; + + ret = xpc_setup_partitions(); + if (ret != 0) { + dev_err(xpc_part, "can't get memory for partition structure\n"); + goto out_1; + } + + xpc_sysctl = register_sysctl_table(xpc_sys_dir); + + /* + * Fill the partition reserved page with the information needed by + * other partitions to discover we are alive and establish initial + * communications. + */ + ret = xpc_setup_rsvd_page(); + if (ret != 0) { + dev_err(xpc_part, "can't setup our reserved page\n"); + goto out_2; + } + + /* add ourselves to the reboot_notifier_list */ + ret = register_reboot_notifier(&xpc_reboot_notifier); + if (ret != 0) + dev_warn(xpc_part, "can't register reboot notifier\n"); + + /* add ourselves to the die_notifier list */ + ret = register_die_notifier(&xpc_die_notifier); + if (ret != 0) + dev_warn(xpc_part, "can't register die notifier\n"); + + /* + * The real work-horse behind xpc. This processes incoming + * interrupts and monitors remote heartbeats. + */ + kthread = kthread_run(xpc_hb_checker, NULL, XPC_HB_CHECK_THREAD_NAME); + if (IS_ERR(kthread)) { + dev_err(xpc_part, "failed while forking hb check thread\n"); + ret = -EBUSY; + goto out_3; + } + + /* + * Startup a thread that will attempt to discover other partitions to + * activate based on info provided by SAL. This new thread is short + * lived and will exit once discovery is complete. + */ + kthread = kthread_run(xpc_initiate_discovery, NULL, + XPC_DISCOVERY_THREAD_NAME); + if (IS_ERR(kthread)) { + dev_err(xpc_part, "failed while forking discovery thread\n"); + + /* mark this new thread as a non-starter */ + complete(&xpc_discovery_exited); + + xpc_do_exit(xpUnloading); + return -EBUSY; + } + + /* set the interface to point at XPC's functions */ + xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect, + xpc_initiate_send, xpc_initiate_send_notify, + xpc_initiate_received, xpc_initiate_partid_to_nasids); + + return 0; + + /* initialization was not successful */ +out_3: + xpc_teardown_rsvd_page(); + + (void)unregister_die_notifier(&xpc_die_notifier); + (void)unregister_reboot_notifier(&xpc_reboot_notifier); +out_2: + if (xpc_sysctl) + unregister_sysctl_table(xpc_sysctl); + + xpc_teardown_partitions(); +out_1: + if (is_uv_system()) + xpc_exit_uv(); + return ret; +} + +module_init(xpc_init); + +static void __exit +xpc_exit(void) +{ + xpc_do_exit(xpUnloading); +} + +module_exit(xpc_exit); + +MODULE_AUTHOR("Silicon Graphics, Inc."); +MODULE_DESCRIPTION("Cross Partition Communication (XPC) support"); +MODULE_LICENSE("GPL"); + +module_param(xpc_hb_interval, int, 0); +MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between " + "heartbeat increments."); + +module_param(xpc_hb_check_interval, int, 0); +MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between " + "heartbeat checks."); + +module_param(xpc_disengage_timelimit, int, 0); +MODULE_PARM_DESC(xpc_disengage_timelimit, "Number of seconds to wait " + "for disengage to complete."); + +module_param(xpc_kdebug_ignore, int, 0); +MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by " + "other partitions when dropping into kdebug."); |