[IA64-SGI] fixes for XPC disengage and open/close protocol

This patch addresses a few issues with the open/close protocol that
were revealed by the newly added disengage functionality combined
with more extensive testing.

Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

5 files changed, 208 insertions, 90 deletions

diff --git a/arch/ia64/sn/kernel/xpc.h b/arch/ia64/sn/kernel/xpc.h
index 565822ab3d08..ae51d7b4c42e 100644
--- a/arch/ia64/sn/kernel/xpc.h
+++ b/arch/ia64/sn/kernel/xpc.h
@@ -417,6 +417,9 @@ struct xpc_channel {
         atomic_t n_on_msg_allocate_wq;   /* #on msg allocation wait queue */
         wait_queue_head_t msg_allocate_wq; /* msg allocation wait queue */
 
+        u8 delayed_IPI_flags;           /* IPI flags received, but delayed */
+                                        /* action until channel disconnected */
+
         /* queue of msg senders who want to be notified when msg received */
 
         atomic_t n_to_notify;           /* #of msg senders to notify */
@@ -478,7 +481,8 @@ struct xpc_channel {
 
 #define XPC_C_DISCONNECTED      0x00002000 /* channel is disconnected */
 #define XPC_C_DISCONNECTING     0x00004000 /* channel is being disconnected */
-#define XPC_C_WDISCONNECT       0x00008000 /* waiting for channel disconnect */
+#define XPC_C_DISCONNECTCALLOUT 0x00008000 /* chan disconnected callout made */
+#define XPC_C_WDISCONNECT       0x00010000 /* waiting for channel disconnect */
 
 
 
@@ -508,13 +512,13 @@ struct xpc_partition {
         int reason_line;                /* line# deactivation initiated from */
         int reactivate_nasid;           /* nasid in partition to reactivate */
 
-        unsigned long disengage_request_timeout; /* timeout in XPC_TICKS */
+        unsigned long disengage_request_timeout; /* timeout in jiffies */
         struct timer_list disengage_request_timer;
 
 
         /* XPC infrastructure referencing and teardown control */
 
-        volatile u8 setup_state;                        /* infrastructure setup state */
+        volatile u8 setup_state;        /* infrastructure setup state */
         wait_queue_head_t teardown_wq;  /* kthread waiting to teardown infra */
         atomic_t references;            /* #of references to infrastructure */
 
@@ -604,7 +608,7 @@ struct xpc_partition {
 
 
 /* number of seconds to wait for other partitions to disengage */
-#define XPC_DISENGAGE_REQUEST_TIMELIMIT 90
+#define XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT 90
 
 /* interval in seconds to print 'waiting disengagement' messages */
 #define XPC_DISENGAGE_PRINTMSG_INTERVAL         10
@@ -618,20 +622,18 @@ struct xpc_partition {
 extern struct xpc_registration xpc_registrations[];
 
 
-/* >>> found in xpc_main.c only */
+/* found in xpc_main.c */
 extern struct device *xpc_part;
 extern struct device *xpc_chan;
+extern int xpc_disengage_request_timelimit;
 extern irqreturn_t xpc_notify_IRQ_handler(int, void *, struct pt_regs *);
 extern void xpc_dropped_IPI_check(struct xpc_partition *);
+extern void xpc_activate_partition(struct xpc_partition *);
 extern void xpc_activate_kthreads(struct xpc_channel *, int);
 extern void xpc_create_kthreads(struct xpc_channel *, int);
 extern void xpc_disconnect_wait(int);
 
 
-/* found in xpc_main.c and efi-xpc.c */
-extern void xpc_activate_partition(struct xpc_partition *);
-
-
 /* found in xpc_partition.c */
 extern int xpc_exiting;
 extern struct xpc_vars *xpc_vars;
@@ -1077,6 +1079,7 @@ xpc_notify_IRQ_send_local(struct xpc_channel *ch, u8 ipi_flag,
 
 /* given an AMO variable and a channel#, get its associated IPI flags */
 #define XPC_GET_IPI_FLAGS(_amo, _c)     ((u8) (((_amo) >> ((_c) * 8)) & 0xff))
+#define XPC_SET_IPI_FLAGS(_amo, _c, _f) (_amo) |= ((u64) (_f) << ((_c) * 8))
 
 #define XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(_amo) ((_amo) & 0x0f0f0f0f0f0f0f0f)
 #define XPC_ANY_MSG_IPI_FLAGS_SET(_amo)       ((_amo) & 0x1010101010101010)
diff --git a/arch/ia64/sn/kernel/xpc_channel.c b/arch/ia64/sn/kernel/xpc_channel.c
index 195ac1b8e262..abf4fc2a87bb 100644
--- a/arch/ia64/sn/kernel/xpc_channel.c
+++ b/arch/ia64/sn/kernel/xpc_channel.c
@@ -792,11 +792,20 @@ xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
                         "reason=%d\n", ch->number, ch->partid, ch->reason);
         }
 
-        /* wake the thread that is waiting for this channel to disconnect */
         if (ch->flags & XPC_C_WDISCONNECT) {
                 spin_unlock_irqrestore(&ch->lock, *irq_flags);
                 up(&ch->wdisconnect_sema);
                 spin_lock_irqsave(&ch->lock, *irq_flags);
+
+        } else if (ch->delayed_IPI_flags) {
+                if (part->act_state != XPC_P_DEACTIVATING) {
+                        /* time to take action on any delayed IPI flags */
+                        spin_lock(&part->IPI_lock);
+                        XPC_SET_IPI_FLAGS(part->local_IPI_amo, ch->number,
+                                                        ch->delayed_IPI_flags);
+                        spin_unlock(&part->IPI_lock);
+                }
+                ch->delayed_IPI_flags = 0;
         }
 }
 
@@ -818,6 +827,19 @@ xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
 
         spin_lock_irqsave(&ch->lock, irq_flags);
 
+again:
+
+        if ((ch->flags & XPC_C_DISCONNECTED) &&
+                                        (ch->flags & XPC_C_WDISCONNECT)) {
+                /*
+                 * Delay processing IPI flags until thread waiting disconnect
+                 * has had a chance to see that the channel is disconnected.
+                 */
+                ch->delayed_IPI_flags |= IPI_flags;
+                spin_unlock_irqrestore(&ch->lock, irq_flags);
+                return;
+        }
+
 
         if (IPI_flags & XPC_IPI_CLOSEREQUEST) {
 
@@ -843,14 +865,22 @@ xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
 
                         /* both sides have finished disconnecting */
                         xpc_process_disconnect(ch, &irq_flags);
+                        DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
+                        goto again;
                 }
 
                 if (ch->flags & XPC_C_DISCONNECTED) {
-                        // >>> explain this section
-
                         if (!(IPI_flags & XPC_IPI_OPENREQUEST)) {
-                                DBUG_ON(part->act_state !=
-                                                        XPC_P_DEACTIVATING);
+                                if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo,
+                                         ch_number) & XPC_IPI_OPENREQUEST)) {
+
+                                        DBUG_ON(ch->delayed_IPI_flags != 0);
+                                        spin_lock(&part->IPI_lock);
+                                        XPC_SET_IPI_FLAGS(part->local_IPI_amo,
+                                                        ch_number,
+                                                        XPC_IPI_CLOSEREQUEST);
+                                        spin_unlock(&part->IPI_lock);
+                                }
                                 spin_unlock_irqrestore(&ch->lock, irq_flags);
                                 return;
                         }
@@ -880,9 +910,13 @@ xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
                         }
 
                         XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
-                } else {
-                        xpc_process_disconnect(ch, &irq_flags);
+
+                        DBUG_ON(IPI_flags & XPC_IPI_CLOSEREPLY);
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+                        return;
                 }
+
+                xpc_process_disconnect(ch, &irq_flags);
         }
 
 
@@ -898,7 +932,20 @@ xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
                 }
 
                 DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
-                DBUG_ON(!(ch->flags & XPC_C_RCLOSEREQUEST));
+
+                if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
+                        if ((XPC_GET_IPI_FLAGS(part->local_IPI_amo, ch_number)
+                                                & XPC_IPI_CLOSEREQUEST)) {
+
+                                DBUG_ON(ch->delayed_IPI_flags != 0);
+                                spin_lock(&part->IPI_lock);
+                                XPC_SET_IPI_FLAGS(part->local_IPI_amo,
+                                                ch_number, XPC_IPI_CLOSEREPLY);
+                                spin_unlock(&part->IPI_lock);
+                        }
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+                        return;
+                }
 
                 ch->flags |= XPC_C_RCLOSEREPLY;
 
@@ -916,8 +963,14 @@ xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
                         "channel=%d\n", args->msg_size, args->local_nentries,
                         ch->partid, ch->number);
 
-                if ((ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) ||
-                                        part->act_state == XPC_P_DEACTIVATING) {
+                if (part->act_state == XPC_P_DEACTIVATING ||
+                                        (ch->flags & XPC_C_ROPENREQUEST)) {
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+                        return;
+                }
+
+                if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_WDISCONNECT)) {
+                        ch->delayed_IPI_flags |= XPC_IPI_OPENREQUEST;
                         spin_unlock_irqrestore(&ch->lock, irq_flags);
                         return;
                 }
@@ -931,8 +984,11 @@ xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
                  *      msg_size = size of channel's messages in bytes
                  *      local_nentries = remote partition's local_nentries
                  */
-                DBUG_ON(args->msg_size == 0);
-                DBUG_ON(args->local_nentries == 0);
+                if (args->msg_size == 0 || args->local_nentries == 0) {
+                        /* assume OPENREQUEST was delayed by mistake */
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+                        return;
+                }
 
                 ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
                 ch->remote_nentries = args->local_nentries;
@@ -970,7 +1026,13 @@ xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
                         spin_unlock_irqrestore(&ch->lock, irq_flags);
                         return;
                 }
-                DBUG_ON(!(ch->flags & XPC_C_OPENREQUEST));
+                if (!(ch->flags & XPC_C_OPENREQUEST)) {
+                        XPC_DISCONNECT_CHANNEL(ch, xpcOpenCloseError,
+                                                                &irq_flags);
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+                        return;
+                }
+
                 DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
                 DBUG_ON(ch->flags & XPC_C_CONNECTED);
 
@@ -1024,8 +1086,8 @@ xpc_connect_channel(struct xpc_channel *ch)
         struct xpc_registration *registration = &xpc_registrations[ch->number];
 
 
-        if (down_interruptible(&registration->sema) != 0) {
-                return xpcInterrupted;
+        if (down_trylock(&registration->sema) != 0) {
+                return xpcRetry;
         }
 
         if (!XPC_CHANNEL_REGISTERED(ch->number)) {
@@ -1445,19 +1507,11 @@ xpc_initiate_connect(int ch_number)
                 if (xpc_part_ref(part)) {
                         ch = &part->channels[ch_number];
 
-                        if (!(ch->flags & XPC_C_DISCONNECTING)) {
-                                DBUG_ON(ch->flags & XPC_C_OPENREQUEST);
-                                DBUG_ON(ch->flags & XPC_C_CONNECTED);
-                                DBUG_ON(ch->flags & XPC_C_SETUP);
-
-                                /*
-                                 * Initiate the establishment of a connection
-                                 * on the newly registered channel to the
-                                 * remote partition.
-                                 */
-                                xpc_wakeup_channel_mgr(part);
-                        }
-
+                        /*
+                         * Initiate the establishment of a connection on the
+                         * newly registered channel to the remote partition.
+                         */
+                        xpc_wakeup_channel_mgr(part);
                         xpc_part_deref(part);
                 }
         }
@@ -1467,9 +1521,6 @@ xpc_initiate_connect(int ch_number)
 void
 xpc_connected_callout(struct xpc_channel *ch)
 {
-        unsigned long irq_flags;
-
-
         /* let the registerer know that a connection has been established */
 
         if (ch->func != NULL) {
@@ -1482,10 +1533,6 @@ xpc_connected_callout(struct xpc_channel *ch)
                 dev_dbg(xpc_chan, "ch->func() returned, reason=xpcConnected, "
                         "partid=%d, channel=%d\n", ch->partid, ch->number);
         }
-
-        spin_lock_irqsave(&ch->lock, irq_flags);
-        ch->flags |= XPC_C_CONNECTCALLOUT;
-        spin_unlock_irqrestore(&ch->lock, irq_flags);
 }
 
 
diff --git a/arch/ia64/sn/kernel/xpc_main.c b/arch/ia64/sn/kernel/xpc_main.c
index feece200b3c3..db349c6d4c58 100644
--- a/arch/ia64/sn/kernel/xpc_main.c
+++ b/arch/ia64/sn/kernel/xpc_main.c
@@ -91,6 +91,10 @@ 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_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
+static int xpc_disengage_request_min_timelimit = 0;
+static int xpc_disengage_request_max_timelimit = 120;
+
 static ctl_table xpc_sys_xpc_hb_dir[] = {
         {
                 1,
@@ -129,6 +133,19 @@ static ctl_table xpc_sys_xpc_dir[] = {
                 0555,
                 xpc_sys_xpc_hb_dir
         },
+        {
+                2,
+                "disengage_request_timelimit",
+                &xpc_disengage_request_timelimit,
+                sizeof(int),
+                0644,
+                NULL,
+                &proc_dointvec_minmax,
+                &sysctl_intvec,
+                NULL,
+                &xpc_disengage_request_min_timelimit,
+                &xpc_disengage_request_max_timelimit
+        },
         {0}
 };
 static ctl_table xpc_sys_dir[] = {
@@ -153,11 +170,11 @@ static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
 
 static unsigned long xpc_hb_check_timeout;
 
-/* used as an indication of when the xpc_hb_checker thread is inactive */
-static DECLARE_MUTEX_LOCKED(xpc_hb_checker_inactive);
+/* notification that the xpc_hb_checker thread has exited */
+static DECLARE_MUTEX_LOCKED(xpc_hb_checker_exited);
 
-/* used as an indication of when the xpc_discovery thread is inactive */
-static DECLARE_MUTEX_LOCKED(xpc_discovery_inactive);
+/* notification that the xpc_discovery thread has exited */
+static DECLARE_MUTEX_LOCKED(xpc_discovery_exited);
 
 
 static struct timer_list xpc_hb_timer;
@@ -181,7 +198,7 @@ xpc_timeout_partition_disengage_request(unsigned long data)
         struct xpc_partition *part = (struct xpc_partition *) data;
 
 
-        DBUG_ON(XPC_TICKS < part->disengage_request_timeout);
+        DBUG_ON(jiffies < part->disengage_request_timeout);
 
         (void) xpc_partition_disengaged(part);
 
@@ -292,8 +309,8 @@ xpc_hb_checker(void *ignore)
         dev_dbg(xpc_part, "heartbeat checker is exiting\n");
 
 
-        /* mark this thread as inactive */
-        up(&xpc_hb_checker_inactive);
+        /* mark this thread as having exited */
+        up(&xpc_hb_checker_exited);
         return 0;
 }
 
@@ -312,8 +329,8 @@ xpc_initiate_discovery(void *ignore)
 
         dev_dbg(xpc_part, "discovery thread is exiting\n");
 
-        /* mark this thread as inactive */
-        up(&xpc_discovery_inactive);
+        /* mark this thread as having exited */
+        up(&xpc_discovery_exited);
         return 0;
 }
 
@@ -703,6 +720,7 @@ xpc_daemonize_kthread(void *args)
         struct xpc_partition *part = &xpc_partitions[partid];
         struct xpc_channel *ch;
         int n_needed;
+        unsigned long irq_flags;
 
 
         daemonize("xpc%02dc%d", partid, ch_number);
@@ -713,11 +731,14 @@ xpc_daemonize_kthread(void *args)
         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) {
+                spin_lock_irqsave(&ch->lock, irq_flags);
+                if (!(ch->flags & XPC_C_CONNECTCALLOUT)) {
+                        ch->flags |= XPC_C_CONNECTCALLOUT;
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+
                         xpc_connected_callout(ch);
 
                         /*
@@ -732,14 +753,23 @@ xpc_daemonize_kthread(void *args)
                                         !(ch->flags & XPC_C_DISCONNECTING)) {
                                 xpc_activate_kthreads(ch, n_needed);
                         }
+                } else {
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
                 }
 
                 xpc_kthread_waitmsgs(part, ch);
         }
 
         if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
-                if (ch->flags & XPC_C_CONNECTCALLOUT) {
+                spin_lock_irqsave(&ch->lock, irq_flags);
+                if ((ch->flags & XPC_C_CONNECTCALLOUT) &&
+                                !(ch->flags & XPC_C_DISCONNECTCALLOUT)) {
+                        ch->flags |= XPC_C_DISCONNECTCALLOUT;
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
+
                         xpc_disconnecting_callout(ch);
+                } else {
+                        spin_unlock_irqrestore(&ch->lock, irq_flags);
                 }
                 if (atomic_dec_return(&part->nchannels_engaged) == 0) {
                         xpc_mark_partition_disengaged(part);
@@ -780,9 +810,29 @@ xpc_create_kthreads(struct xpc_channel *ch, int needed)
 
 
         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.
+                 */
+                (void) xpc_part_ref(part);
+                xpc_msgqueue_ref(ch);
+                if (atomic_inc_return(&ch->kthreads_assigned) == 1 &&
+                    atomic_inc_return(&part->nchannels_engaged) == 1) {
+                        xpc_mark_partition_engaged(part);
+                }
+
                 pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
                 if (pid < 0) {
                         /* the fork failed */
+                        if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
+                            atomic_dec_return(&part->nchannels_engaged) == 0) {
+                                xpc_mark_partition_disengaged(part);
+                                xpc_IPI_send_disengage(part);
+                        }
+                        xpc_msgqueue_deref(ch);
+                        xpc_part_deref(part);
 
                         if (atomic_read(&ch->kthreads_assigned) <
                                                 ch->kthreads_idle_limit) {
@@ -802,18 +852,6 @@ xpc_create_kthreads(struct xpc_channel *ch, int needed)
                         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(part);
-                xpc_msgqueue_ref(ch);
-                if (atomic_inc_return(&ch->kthreads_assigned) == 1) {
-                        if (atomic_inc_return(&part->nchannels_engaged) == 1) {
-                                xpc_mark_partition_engaged(part);
-                        }
-                }
                 ch->kthreads_created++; // >>> temporary debug only!!!
         }
 }
@@ -826,26 +864,49 @@ xpc_disconnect_wait(int ch_number)
         partid_t 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 = 1; partid < XP_MAX_PARTITIONS; partid++) {
                 part = &xpc_partitions[partid];
 
-                if (xpc_part_ref(part)) {
-                        ch = &part->channels[ch_number];
+                if (!xpc_part_ref(part)) {
+                        continue;
+                }
 
-                        if (ch->flags & XPC_C_WDISCONNECT) {
-                                if (!(ch->flags & XPC_C_DISCONNECTED)) {
-                                        (void) down(&ch->wdisconnect_sema);
-                                }
-                                spin_lock_irqsave(&ch->lock, irq_flags);
-                                ch->flags &= ~XPC_C_WDISCONNECT;
-                                spin_unlock_irqrestore(&ch->lock, irq_flags);
-                        }
+                ch = &part->channels[ch_number];
 
+                if (!(ch->flags & XPC_C_WDISCONNECT)) {
                         xpc_part_deref(part);
+                        continue;
                 }
+
+                (void) down(&ch->wdisconnect_sema);
+
+                spin_lock_irqsave(&ch->lock, irq_flags);
+                DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
+                wakeup_channel_mgr = 0;
+
+                if (ch->delayed_IPI_flags) {
+                        if (part->act_state != XPC_P_DEACTIVATING) {
+                                spin_lock(&part->IPI_lock);
+                                XPC_SET_IPI_FLAGS(part->local_IPI_amo,
+                                        ch->number, ch->delayed_IPI_flags);
+                                spin_unlock(&part->IPI_lock);
+                                wakeup_channel_mgr = 1;
+                        }
+                        ch->delayed_IPI_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);
         }
 }
 
@@ -873,11 +934,11 @@ xpc_do_exit(enum xpc_retval reason)
         /* ignore all incoming interrupts */
         free_irq(SGI_XPC_ACTIVATE, NULL);
 
-        /* wait for the discovery thread to mark itself inactive */
-        down(&xpc_discovery_inactive);
+        /* wait for the discovery thread to exit */
+        down(&xpc_discovery_exited);
 
-        /* wait for the heartbeat checker thread to mark itself inactive */
-        down(&xpc_hb_checker_inactive);
+        /* wait for the heartbeat checker thread to exit */
+        down(&xpc_hb_checker_exited);
 
 
         /* sleep for a 1/3 of a second or so */
@@ -893,6 +954,7 @@ xpc_do_exit(enum xpc_retval reason)
 
                 for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
                         part = &xpc_partitions[partid];
+
                         if (xpc_partition_disengaged(part) &&
                                         part->act_state == XPC_P_INACTIVE) {
                                 continue;
@@ -930,7 +992,7 @@ xpc_do_exit(enum xpc_retval reason)
 
         /* now it's time to eliminate our heartbeat */
         del_timer_sync(&xpc_hb_timer);
-        DBUG_ON(xpc_vars->heartbeating_to_mask == 0);
+        DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
 
         /* take ourselves off of the reboot_notifier_list */
         (void) unregister_reboot_notifier(&xpc_reboot_notifier);
@@ -1134,7 +1196,7 @@ xpc_init(void)
                 dev_err(xpc_part, "failed while forking discovery thread\n");
 
                 /* mark this new thread as a non-starter */
-                up(&xpc_discovery_inactive);
+                up(&xpc_discovery_exited);
 
                 xpc_do_exit(xpcUnloading);
                 return -EBUSY;
@@ -1172,3 +1234,7 @@ 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_request_timelimit, int, 0);
+MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
+                "for disengage request to complete.");
+
diff --git a/arch/ia64/sn/kernel/xpc_partition.c b/arch/ia64/sn/kernel/xpc_partition.c
index 79a0fc4c860c..958488f55699 100644
--- a/arch/ia64/sn/kernel/xpc_partition.c
+++ b/arch/ia64/sn/kernel/xpc_partition.c
@@ -578,7 +578,7 @@ xpc_update_partition_info(struct xpc_partition *part, u8 remote_rp_version,
 
 
 /*
- * Prior code has determine the nasid which generated an IPI.  Inspect
+ * Prior code has determined the nasid which generated an IPI.  Inspect
  * that nasid to determine if its partition needs to be activated or
  * deactivated.
  *
@@ -942,14 +942,14 @@ xpc_deactivate_partition(const int line, struct xpc_partition *part,
 
                 /* set a timelimit on the disengage request */
                 part->disengage_request_timeout = jiffies +
-                                        (XPC_DISENGAGE_REQUEST_TIMELIMIT * HZ);
+                                        (xpc_disengage_request_timelimit * HZ);
                 part->disengage_request_timer.expires =
                                         part->disengage_request_timeout;
                 add_timer(&part->disengage_request_timer);
         }
 
-        dev_dbg(xpc_part, "bringing partition %d down, reason = %d\n", partid,
-                reason);
+        dev_dbg(xpc_part, "bringing partition %d down, reason = %d\n",
+                XPC_PARTID(part), reason);
 
         xpc_partition_going_down(part, reason);
 }
diff --git a/include/asm-ia64/sn/xp.h b/include/asm-ia64/sn/xp.h
index f3052a54932b..30312be31206 100644
--- a/include/asm-ia64/sn/xp.h
+++ b/include/asm-ia64/sn/xp.h
@@ -225,7 +225,9 @@ enum xpc_retval {
 
         xpcDisconnecting,       /* 49: channel disconnecting (closing) */
 
-        xpcUnknownReason        /* 50: unknown reason -- must be last in list */
+        xpcOpenCloseError,      /* 50: channel open/close protocol error */
+
+        xpcUnknownReason        /* 51: unknown reason -- must be last in list */
 };
 
 
@@ -350,7 +352,7 @@ typedef void (*xpc_notify_func)(enum xpc_retval reason, partid_t partid,
  *
  * The 'func' field points to the function to call when aynchronous
  * notification is required for such events as: a connection established/lost,
- * or an incomming message received, or an error condition encountered. A
+ * or an incoming message received, or an error condition encountered. A
  * non-NULL 'func' field indicates that there is an active registration for
  * the channel.
  */