--- /dev/null
+/*
+ * 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.
+ *
+ * Copyright (c) 2004-2005 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:
+ *
+ * . We currently have no way to determine which nasid an IPI came
+ * from. Thus, xpc_IPI_send() 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/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include <linux/cache.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <asm/sn/intr.h>
+#include <asm/sn/sn_sal.h>
+#include <asm/uaccess.h>
+#include "xpc.h"
+
+
+/* define two XPC debug device structures to be used with dev_dbg() et al */
+
+struct device_driver xpc_dbg_name = {
+ .name = "xpc"
+};
+
+struct device xpc_part_dbg_subname = {
+ .bus_id = {0}, /* set to "part" at xpc_init() time */
+ .driver = &xpc_dbg_name
+};
+
+struct device xpc_chan_dbg_subname = {
+ .bus_id = {0}, /* 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;
+
+
+/* systune related variables for /proc/sys directories */
+
+static int xpc_hb_min = 1;
+static int xpc_hb_max = 10;
+
+static int xpc_hb_check_min = 10;
+static int xpc_hb_check_max = 120;
+
+static ctl_table xpc_sys_xpc_hb_dir[] = {
+ {
+ 1,
+ "hb_interval",
+ &xpc_hb_interval,
+ sizeof(int),
+ 0644,
+ NULL,
+ &proc_dointvec_minmax,
+ &sysctl_intvec,
+ NULL,
+ &xpc_hb_min, &xpc_hb_max
+ },
+ {
+ 2,
+ "hb_check_interval",
+ &xpc_hb_check_interval,
+ sizeof(int),
+ 0644,
+ NULL,
+ &proc_dointvec_minmax,
+ &sysctl_intvec,
+ NULL,
+ &xpc_hb_check_min, &xpc_hb_check_max
+ },
+ {0}
+};
+static ctl_table xpc_sys_xpc_dir[] = {
+ {
+ 1,
+ "hb",
+ NULL,
+ 0,
+ 0555,
+ xpc_sys_xpc_hb_dir
+ },
+ {0}
+};
+static ctl_table xpc_sys_dir[] = {
+ {
+ 1,
+ "xpc",
+ NULL,
+ 0,
+ 0555,
+ xpc_sys_xpc_dir
+ },
+ {0}
+};
+static struct ctl_table_header *xpc_sysctl;
+
+
+/* #of IRQs received */
+static atomic_t xpc_act_IRQ_rcvd;
+
+/* IRQ handler notifies this wait queue on receipt of an IRQ */
+static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
+
+static unsigned long xpc_hb_check_timeout;
+
+/* xpc_hb_checker thread exited notification */
+static DECLARE_MUTEX_LOCKED(xpc_hb_checker_exited);
+
+/* xpc_discovery thread exited notification */
+static DECLARE_MUTEX_LOCKED(xpc_discovery_exited);
+
+
+static struct timer_list xpc_hb_timer;
+
+
+static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
+
+
+/*
+ * Notify the heartbeat check thread that an IRQ has been received.
+ */
+static irqreturn_t
+xpc_act_IRQ_handler(int irq, void *dev_id, struct pt_regs *regs)
+{
+ atomic_inc(&xpc_act_IRQ_rcvd);
+ wake_up_interruptible(&xpc_act_IRQ_wq);
+ return IRQ_HANDLED;
+}
+
+
+/*
+ * 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(unsigned long dummy)
+{
+ xpc_vars->heartbeat++;
+
+ if (jiffies >= xpc_hb_check_timeout) {
+ wake_up_interruptible(&xpc_act_IRQ_wq);
+ }
+
+ xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
+ add_timer(&xpc_hb_timer);
+}
+
+
+/*
+ * This thread is responsible for nearly all of the partition
+ * activation/deactivation.
+ */
+static int
+xpc_hb_checker(void *ignore)
+{
+ int last_IRQ_count = 0;
+ int new_IRQ_count;
+ int force_IRQ=0;
+
+
+ /* this thread was marked active by xpc_hb_init() */
+
+ daemonize(XPC_HB_CHECK_THREAD_NAME);
+
+ set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
+
+ xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
+
+ while (!(volatile int) xpc_exiting) {
+
+ /* wait for IRQ or timeout */
+ (void) wait_event_interruptible(xpc_act_IRQ_wq,
+ (last_IRQ_count < atomic_read(&xpc_act_IRQ_rcvd) ||
+ jiffies >= xpc_hb_check_timeout ||
+ (volatile int) xpc_exiting));
+
+ dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
+ "been received\n",
+ (int) (xpc_hb_check_timeout - jiffies),
+ atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
+
+
+ /* checking of remote heartbeats is skewed by IRQ handling */
+ if (jiffies >= xpc_hb_check_timeout) {
+ dev_dbg(xpc_part, "checking remote heartbeats\n");
+ xpc_check_remote_hb();
+
+ /*
+ * We need to periodically recheck to ensure no
+ * IPI/AMO pairs have been missed. That check
+ * must always reset xpc_hb_check_timeout.
+ */
+ force_IRQ = 1;
+ }
+
+
+ new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
+ if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
+ force_IRQ = 0;
+
+ dev_dbg(xpc_part, "found an IRQ to process; will be "
+ "resetting xpc_hb_check_timeout\n");
+
+ last_IRQ_count += xpc_identify_act_IRQ_sender();
+ if (last_IRQ_count < new_IRQ_count) {
+ /* retry once to help avoid missing AMO */
+ (void) xpc_identify_act_IRQ_sender();
+ }
+ last_IRQ_count = new_IRQ_count;
+
+ xpc_hb_check_timeout = jiffies +
+ (xpc_hb_check_interval * HZ);
+ }
+ }
+
+ dev_dbg(xpc_part, "heartbeat checker is exiting\n");
+
+
+ /* mark this thread as inactive */
+ up(&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)
+{
+ daemonize(XPC_DISCOVERY_THREAD_NAME);
+
+ xpc_discovery();
+
+ dev_dbg(xpc_part, "discovery thread is exiting\n");
+
+ /* mark this thread as inactive */
+ up(&xpc_discovery_exited);
+ return 0;
+}
+
+
+/*
+ * Establish first contact with the remote partititon. This involves pulling
+ * the XPC per partition variables from the remote partition and waiting for
+ * the remote partition to pull ours.
+ */
+static enum xpc_retval
+xpc_make_first_contact(struct xpc_partition *part)
+{
+ enum xpc_retval ret;
+
+
+ while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
+ if (ret != xpcRetry) {
+ XPC_DEACTIVATE_PARTITION(part, ret);
+ return ret;
+ }
+
+ dev_dbg(xpc_chan, "waiting to make first contact with "
+ "partition %d\n", XPC_PARTID(part));
+
+ /* wait a 1/4 of a second or so */
+ set_current_state(TASK_INTERRUPTIBLE);
+ (void) schedule_timeout(0.25 * HZ);
+
+ if (part->act_state == XPC_P_DEACTIVATING) {
+ return part->reason;
+ }
+ }
+
+ return xpc_mark_partition_active(part);
+}
+
+
+/*
+ * The first kthread assigned to a newly activated partition is the one
+ * created by XPC HB with which it calls xpc_partition_up(). 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_DEACTIVATING ||
+ atomic_read(&part->nchannels_active) > 0) {
+
+ xpc_process_channel_activity(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 ||
+ (volatile u64) part->local_IPI_amo != 0 ||
+ ((volatile u8) part->act_state ==
+ XPC_P_DEACTIVATING &&
+ atomic_read(&part->nchannels_active) == 0)));
+ atomic_set(&part->channel_mgr_requests, 1);
+
+ // >>> Does it need to wakeup periodically as well? In case we
+ // >>> miscalculated the #of kthreads to wakeup or create?
+ }
+}
+
+
+/*
+ * 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 until the partition
+ * goes down. At which time the kthread will teardown the XPC infrastructure
+ * and then exit.
+ *
+ * XPC HB will put the remote partition's XPC per partition specific variables
+ * physical address into xpc_partitions[partid].remote_vars_part_pa prior to
+ * calling xpc_partition_up().
+ */
+static void
+xpc_partition_up(struct xpc_partition *part)
+{
+ DBUG_ON(part->channels != NULL);
+
+ dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
+
+ if (xpc_setup_infrastructure(part) != xpcSuccess) {
+ return;
+ }
+
+ /*
+ * The kthread that XPC HB called us with will become the
+ * channel manager for this partition. It will not return
+ * back to XPC HB until the partition's XPC infrastructure
+ * has been dismantled.
+ */
+
+ (void) xpc_part_ref(part); /* this will always succeed */
+
+ if (xpc_make_first_contact(part) == xpcSuccess) {
+ xpc_channel_mgr(part);
+ }
+
+ xpc_part_deref(part);
+
+ xpc_teardown_infrastructure(part);
+}
+
+
+static int
+xpc_activating(void *__partid)
+{
+ partid_t partid = (u64) __partid;
+ struct xpc_partition *part = &xpc_partitions[partid];
+ unsigned long irq_flags;
+ struct sched_param param = { sched_priority: MAX_USER_RT_PRIO - 1 };
+ int ret;
+
+
+ DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
+
+ spin_lock_irqsave(&part->act_lock, irq_flags);
+
+ if (part->act_state == XPC_P_DEACTIVATING) {
+ part->act_state = XPC_P_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_ACTIVATION_REQ);
+ part->act_state = XPC_P_ACTIVATING;
+
+ XPC_SET_REASON(part, 0, 0);
+ spin_unlock_irqrestore(&part->act_lock, irq_flags);
+
+ dev_dbg(xpc_part, "bringing partition %d up\n", partid);
+
+ daemonize("xpc%02d", partid);
+
+ /*
+ * This thread needs to run at a realtime priority to prevent a
+ * significant performance degradation.
+ */
+ ret = sched_setscheduler(current, SCHED_FIFO, ¶m);
+ if (ret != 0) {
+ dev_warn(xpc_part, "unable to set pid %d to a realtime "
+ "priority, ret=%d\n", current->pid, ret);
+ }
+
+ /* allow this thread and its children to run on any CPU */
+ set_cpus_allowed(current, CPU_MASK_ALL);
+
+ /*
+ * Register the remote partition's AMOs with SAL so it can handle
+ * and cleanup errors within that address range should the remote
+ * partition go down. We don't unregister this range because it is
+ * difficult to tell when outstanding writes to the remote partition
+ * are finished and thus when it is safe to unregister. This should
+ * not result in wasted space in the SAL xp_addr_region table because
+ * we should get the same page for remote_amos_page_pa after module
+ * reloads and system reboots.
+ */
+ if (sn_register_xp_addr_region(part->remote_amos_page_pa,
+ PAGE_SIZE, 1) < 0) {
+ dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
+ "xp_addr region\n", partid);
+
+ spin_lock_irqsave(&part->act_lock, irq_flags);
+ part->act_state = XPC_P_INACTIVE;
+ XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
+ spin_unlock_irqrestore(&part->act_lock, irq_flags);
+ part->remote_rp_pa = 0;
+ return 0;
+ }
+
+ XPC_ALLOW_HB(partid, xpc_vars);
+ xpc_IPI_send_activated(part);
+
+
+ /*
+ * xpc_partition_up() holds this thread and marks this partition as
+ * XPC_P_ACTIVE by calling xpc_hb_mark_active().
+ */
+ (void) xpc_partition_up(part);
+
+ xpc_mark_partition_inactive(part);
+
+ if (part->reason == xpcReactivating) {
+ /* interrupting ourselves results in activating partition */
+ xpc_IPI_send_reactivate(part);
+ }
+
+ return 0;
+}
+
+
+void
+xpc_activate_partition(struct xpc_partition *part)
+{
+ partid_t partid = XPC_PARTID(part);
+ unsigned long irq_flags;
+ pid_t pid;
+
+
+ spin_lock_irqsave(&part->act_lock, irq_flags);
+
+ pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
+
+ DBUG_ON(part->act_state != XPC_P_INACTIVE);
+
+ if (pid > 0) {
+ part->act_state = XPC_P_ACTIVATION_REQ;
+ XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
+ } else {
+ XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
+ }
+
+ spin_unlock_irqrestore(&part->act_lock, irq_flags);
+}
+
+
+/*
+ * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
+ * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
+ * than one partition, we use an AMO_t structure per partition to indicate
+ * whether a partition has sent an IPI or not. >>> If it has, then wake up the
+ * associated kthread to handle it.
+ *
+ * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
+ * running on other partitions.
+ *
+ * Noteworthy Arguments:
+ *
+ * irq - Interrupt ReQuest number. NOT USED.
+ *
+ * dev_id - partid of IPI's potential sender.
+ *
+ * regs - processor's context before the processor entered
+ * interrupt code. NOT USED.
+ */
+irqreturn_t
+xpc_notify_IRQ_handler(int irq, void *dev_id, struct pt_regs *regs)
+{
+ partid_t partid = (partid_t) (u64) dev_id;
+ struct xpc_partition *part = &xpc_partitions[partid];
+
+
+ DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
+
+ if (xpc_part_ref(part)) {
+ xpc_check_for_channel_activity(part);
+
+ xpc_part_deref(part);
+ }
+ return IRQ_HANDLED;
+}
+
+
+/*
+ * Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
+ * because the write to their associated IPI amo completed after the IRQ/IPI
+ * was received.
+ */
+void
+xpc_dropped_IPI_check(struct xpc_partition *part)
+{
+ if (xpc_part_ref(part)) {
+ xpc_check_for_channel_activity(part);
+
+ part->dropped_IPI_timer.expires = jiffies +
+ XPC_P_DROPPED_IPI_WAIT;
+ add_timer(&part->dropped_IPI_timer);
+ xpc_part_deref(part);
+ }
+}
+
+
+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;
+ // >>>should never be less than 0
+ 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);
+}
+
+
+/*
+ * 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)
+{
+ do {
+ /* deliver messages to their intended recipients */
+
+ while ((volatile s64) ch->w_local_GP.get <
+ (volatile s64) ch->w_remote_GP.put &&
+ !((volatile u32) ch->flags &
+ XPC_C_DISCONNECTING)) {
+ xpc_deliver_msg(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,
+ ((volatile s64) ch->w_local_GP.get <
+ (volatile s64) ch->w_remote_GP.put ||
+ ((volatile u32) ch->flags &
+ XPC_C_DISCONNECTING)));
+
+ atomic_dec(&ch->kthreads_idle);
+
+ } while (!((volatile u32) ch->flags & XPC_C_DISCONNECTING));
+}
+
+
+static int
+xpc_daemonize_kthread(void *args)
+{
+ partid_t 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;
+
+
+ daemonize("xpc%02dc%d", partid, ch_number);
+
+ 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)) {
+ DBUG_ON(!(ch->flags & XPC_C_CONNECTED));
+
+ /* let registerer know that connection has been established */
+
+ if (atomic_read(&ch->kthreads_assigned) == 1) {
+ xpc_connected_callout(ch);
+
+ /*
+ * 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 = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
+ if (n_needed > 0 &&
+ !(ch->flags & XPC_C_DISCONNECTING)) {
+ xpc_activate_kthreads(ch, n_needed);
+ }
+ }
+
+ xpc_kthread_waitmsgs(part, ch);
+ }
+
+ if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
+ ((ch->flags & XPC_C_CONNECTCALLOUT) ||
+ (ch->reason != xpcUnregistering &&
+ ch->reason != xpcOtherUnregistering))) {
+ xpc_disconnected_callout(ch);
+ }
+
+
+ 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)
+{
+ unsigned long irq_flags;
+ pid_t pid;
+ u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
+
+
+ while (needed-- > 0) {
+ pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
+ if (pid < 0) {
+ /* the fork failed */
+
+ 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.
+ *
+ * No xpc_msgqueue_ref() is needed here since
+ * the channel mgr is doing this.
+ */
+ spin_lock_irqsave(&ch->lock, irq_flags);
+ XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
+ &irq_flags);
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ }
+ break;
+ }
+
+ /*
+ * 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.
+ */
+ (void) xpc_part_ref(&xpc_partitions[ch->partid]);
+ xpc_msgqueue_ref(ch);
+ atomic_inc(&ch->kthreads_assigned);
+ ch->kthreads_created++; // >>> temporary debug only!!!
+ }
+}
+
+
+void
+xpc_disconnect_wait(int ch_number)
+{
+ partid_t partid;
+ struct xpc_partition *part;
+ struct xpc_channel *ch;
+
+
+ /* now wait for all callouts to the caller's function to cease */
+ for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
+ part = &xpc_partitions[partid];
+
+ if (xpc_part_ref(part)) {
+ ch = &part->channels[ch_number];
+
+// >>> how do we keep from falling into the window between our check and going
+// >>> down and coming back up where sema is re-inited?
+ if (ch->flags & XPC_C_SETUP) {
+ (void) down(&ch->teardown_sema);
+ }
+
+ xpc_part_deref(part);
+ }
+ }
+}
+
+
+static void
+xpc_do_exit(void)
+{
+ partid_t partid;
+ int active_part_count;
+ struct xpc_partition *part;
+
+
+ /* now it's time to eliminate our heartbeat */
+ del_timer_sync(&xpc_hb_timer);
+ xpc_vars->heartbeating_to_mask = 0;
+
+ /* indicate to others that our reserved page is uninitialized */
+ xpc_rsvd_page->vars_pa = 0;
+
+ /*
+ * Ignore all incoming interrupts. Without interupts the heartbeat
+ * checker won't activate any new partitions that may come up.
+ */
+ free_irq(SGI_XPC_ACTIVATE, NULL);
+
+ /*
+ * Cause the heartbeat checker and the discovery threads to exit.
+ * We don't want them attempting to activate new partitions as we
+ * try to deactivate the existing ones.
+ */
+ xpc_exiting = 1;
+ wake_up_interruptible(&xpc_act_IRQ_wq);
+
+ /* wait for the heartbeat checker thread to mark itself inactive */
+ down(&xpc_hb_checker_exited);
+
+ /* wait for the discovery thread to mark itself inactive */
+ down(&xpc_discovery_exited);
+
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(0.3 * HZ);
+ set_current_state(TASK_RUNNING);
+
+
+ /* wait for all partitions to become inactive */
+
+ do {
+ active_part_count = 0;
+
+ for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
+ part = &xpc_partitions[partid];
+ if (part->act_state != XPC_P_INACTIVE) {
+ active_part_count++;
+
+ XPC_DEACTIVATE_PARTITION(part, xpcUnloading);
+ }
+ }
+
+ if (active_part_count) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(0.3 * HZ);
+ set_current_state(TASK_RUNNING);
+ }
+
+ } while (active_part_count > 0);
+
+
+ /* close down protections for IPI operations */
+ xpc_restrict_IPI_ops();
+
+
+ /* clear the interface to XPC's functions */
+ xpc_clear_interface();
+
+ if (xpc_sysctl) {
+ unregister_sysctl_table(xpc_sysctl);
+ }
+}
+
+
+int __init
+xpc_init(void)
+{
+ int ret;
+ partid_t partid;
+ struct xpc_partition *part;
+ pid_t pid;
+
+
+ /*
+ * xpc_remote_copy_buffer is used as a temporary buffer for bte_copy'ng
+ * both a partition's reserved page and its XPC variables. Its size was
+ * based on the size of a reserved page. So we need to ensure that the
+ * XPC variables will fit as well.
+ */
+ if (XPC_VARS_ALIGNED_SIZE > XPC_RSVD_PAGE_ALIGNED_SIZE) {
+ dev_err(xpc_part, "xpc_remote_copy_buffer is not big enough\n");
+ return -EPERM;
+ }
+ DBUG_ON((u64) xpc_remote_copy_buffer !=
+ L1_CACHE_ALIGN((u64) xpc_remote_copy_buffer));
+
+ snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
+ snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
+
+ xpc_sysctl = register_sysctl_table(xpc_sys_dir, 1);
+
+ /*
+ * 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 = 1; partid < XP_MAX_PARTITIONS; partid++) {
+ part = &xpc_partitions[partid];
+
+ DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
+
+ part->act_IRQ_rcvd = 0;
+ spin_lock_init(&part->act_lock);
+ part->act_state = XPC_P_INACTIVE;
+ XPC_SET_REASON(part, 0, 0);
+ part->setup_state = XPC_P_UNSET;
+ init_waitqueue_head(&part->teardown_wq);
+ atomic_set(&part->references, 0);
+ }
+
+ /*
+ * Open up protections for IPI operations (and AMO operations on
+ * Shub 1.1 systems).
+ */
+ xpc_allow_IPI_ops();
+
+ /*
+ * Interrupts being processed will increment this atomic variable and
+ * awaken the heartbeat thread which will process the interrupts.
+ */
+ atomic_set(&xpc_act_IRQ_rcvd, 0);
+
+ /*
+ * This is safe to do before the xpc_hb_checker thread has started
+ * because the handler releases a wait queue. If an interrupt is
+ * received before the thread is waiting, it will not go to sleep,
+ * but rather immediately process the interrupt.
+ */
+ ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
+ "xpc hb", NULL);
+ if (ret != 0) {
+ dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
+ "errno=%d\n", -ret);
+
+ xpc_restrict_IPI_ops();
+
+ if (xpc_sysctl) {
+ unregister_sysctl_table(xpc_sysctl);
+ }
+ return -EBUSY;
+ }
+
+ /*
+ * Fill the partition reserved page with the information needed by
+ * other partitions to discover we are alive and establish initial
+ * communications.
+ */
+ xpc_rsvd_page = xpc_rsvd_page_init();
+ if (xpc_rsvd_page == NULL) {
+ dev_err(xpc_part, "could not setup our reserved page\n");
+
+ free_irq(SGI_XPC_ACTIVATE, NULL);
+ xpc_restrict_IPI_ops();
+
+ if (xpc_sysctl) {
+ unregister_sysctl_table(xpc_sysctl);
+ }
+ return -EBUSY;
+ }
+
+
+ /*
+ * Set the beating to other partitions into motion. This is
+ * the last requirement for other partitions' discovery to
+ * initiate communications with us.
+ */
+ init_timer(&xpc_hb_timer);
+ xpc_hb_timer.function = xpc_hb_beater;
+ xpc_hb_beater(0);
+
+
+ /*
+ * The real work-horse behind xpc. This processes incoming
+ * interrupts and monitors remote heartbeats.
+ */
+ pid = kernel_thread(xpc_hb_checker, NULL, 0);
+ if (pid < 0) {
+ dev_err(xpc_part, "failed while forking hb check thread\n");
+
+ /* indicate to others that our reserved page is uninitialized */
+ xpc_rsvd_page->vars_pa = 0;
+
+ del_timer_sync(&xpc_hb_timer);
+ free_irq(SGI_XPC_ACTIVATE, NULL);
+ xpc_restrict_IPI_ops();
+
+ if (xpc_sysctl) {
+ unregister_sysctl_table(xpc_sysctl);
+ }
+ return -EBUSY;
+ }
+
+
+ /*
+ * 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.
+ */
+ pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
+ if (pid < 0) {
+ dev_err(xpc_part, "failed while forking discovery thread\n");
+
+ /* mark this new thread as a non-starter */
+ up(&xpc_discovery_exited);
+
+ xpc_do_exit();
+ return -EBUSY;
+ }
+
+
+ /* set the interface to point at XPC's functions */
+ xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
+ xpc_initiate_allocate, xpc_initiate_send,
+ xpc_initiate_send_notify, xpc_initiate_received,
+ xpc_initiate_partid_to_nasids);
+
+ return 0;
+}
+module_init(xpc_init);
+
+
+void __exit
+xpc_exit(void)
+{
+ xpc_do_exit();
+}
+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.");
+
git://git.onelab.eu / linux-2.6.git / blobdiff