Pull xpc-disengage into release branch

4 files changed, 1130 insertions, 368 deletions

diff --git a/arch/ia64/sn/kernel/xpc.h b/arch/ia64/sn/kernel/xpc.h
index d0ee635daf2e..33df1b3758b6 100644
--- a/arch/ia64/sn/kernel/xpc.h
+++ b/arch/ia64/sn/kernel/xpc.h
@@ -57,7 +57,7 @@
 #define XPC_NASID_FROM_W_B(_w, _b) (((_w) * 64 + (_b)) * 2)
 
 #define XPC_HB_DEFAULT_INTERVAL		5	/* incr HB every x secs */
-#define XPC_HB_CHECK_DEFAULT_TIMEOUT	20	/* check HB every x secs */
+#define XPC_HB_CHECK_DEFAULT_INTERVAL	20	/* check HB every x secs */
 
 /* define the process name of HB checker and the CPU it is pinned to */
 #define XPC_HB_CHECK_THREAD_NAME	"xpc_hb"
@@ -67,34 +67,82 @@
 #define XPC_DISCOVERY_THREAD_NAME	"xpc_discovery"
 
 
-#define XPC_HB_ALLOWED(_p, _v)	((_v)->heartbeating_to_mask & (1UL << (_p)))
-#define XPC_ALLOW_HB(_p, _v)	(_v)->heartbeating_to_mask |= (1UL << (_p))
-#define XPC_DISALLOW_HB(_p, _v)	(_v)->heartbeating_to_mask &= (~(1UL << (_p)))
-
-
 /*
- * Reserved Page provided by SAL.
+ * the reserved page
+ *
+ *   SAL reserves one page of memory per partition for XPC. Though a full page
+ *   in length (16384 bytes), its starting address is not page aligned, but it
+ *   is cacheline aligned. The reserved page consists of the following:
+ *
+ *   reserved page header
+ *
+ *     The first cacheline of the reserved page contains the header
+ *     (struct xpc_rsvd_page). Before SAL initialization has completed,
+ *     SAL has set up the following fields of the reserved page header:
+ *     SAL_signature, SAL_version, partid, and nasids_size. The other
+ *     fields are set up by XPC. (xpc_rsvd_page points to the local
+ *     partition's reserved page.)
  *
- * SAL provides one page per partition of reserved memory.  When SAL
- * initialization is complete, SAL_signature, SAL_version, partid,
- * part_nasids, and mach_nasids are set.
+ *   part_nasids mask
+ *   mach_nasids mask
+ *
+ *     SAL also sets up two bitmaps (or masks), one that reflects the actual
+ *     nasids in this partition (part_nasids), and the other that reflects
+ *     the actual nasids in the entire machine (mach_nasids). We're only
+ *     interested in the even numbered nasids (which contain the processors
+ *     and/or memory), so we only need half as many bits to represent the
+ *     nasids. The part_nasids mask is located starting at the first cacheline
+ *     following the reserved page header. The mach_nasids mask follows right
+ *     after the part_nasids mask. The size in bytes of each mask is reflected
+ *     by the reserved page header field 'nasids_size'. (Local partition's
+ *     mask pointers are xpc_part_nasids and xpc_mach_nasids.)
+ *
+ *   vars
+ *   vars part
+ *
+ *     Immediately following the mach_nasids mask are the XPC variables
+ *     required by other partitions. First are those that are generic to all
+ *     partitions (vars), followed on the next available cacheline by those
+ *     which are partition specific (vars part). These are setup by XPC.
+ *     (Local partition's vars pointers are xpc_vars and xpc_vars_part.)
  *
  * Note: Until vars_pa is set, the partition XPC code has not been initialized.
  */
 struct xpc_rsvd_page {
-	u64 SAL_signature;	/* SAL unique signature */
-	u64 SAL_version;	/* SAL specified version */
-	u8 partid;		/* partition ID from SAL */
+	u64 SAL_signature;	/* SAL: unique signature */
+	u64 SAL_version;	/* SAL: version */
+	u8 partid;		/* SAL: partition ID */
 	u8 version;
-	u8 pad[6];		/* pad to u64 align */
+	u8 pad1[6];		/* align to next u64 in cacheline */
 	volatile u64 vars_pa;
-	u64 part_nasids[XP_NASID_MASK_WORDS] ____cacheline_aligned;
-	u64 mach_nasids[XP_NASID_MASK_WORDS] ____cacheline_aligned;
+	struct timespec stamp;	/* time when reserved page was setup by XPC */
+	u64 pad2[9];		/* align to last u64 in cacheline */
+	u64 nasids_size;	/* SAL: size of each nasid mask in bytes */
 };
-#define XPC_RP_VERSION _XPC_VERSION(1,0) /* version 1.0 of the reserved page */
 
-#define XPC_RSVD_PAGE_ALIGNED_SIZE \
-			(L1_CACHE_ALIGN(sizeof(struct xpc_rsvd_page)))
+#define XPC_RP_VERSION _XPC_VERSION(1,1) /* version 1.1 of the reserved page */
+
+#define XPC_SUPPORTS_RP_STAMP(_version) \
+			(_version >= _XPC_VERSION(1,1))
+
+/*
+ * compare stamps - the return value is:
+ *
+ *	< 0,	if stamp1 < stamp2
+ *	= 0,	if stamp1 == stamp2
+ *	> 0,	if stamp1 > stamp2
+ */
+static inline int
+xpc_compare_stamps(struct timespec *stamp1, struct timespec *stamp2)
+{
+	int ret;
+
+
+	if ((ret = stamp1->tv_sec - stamp2->tv_sec) == 0) {
+		ret = stamp1->tv_nsec - stamp2->tv_nsec;
+	}
+	return ret;
+}
 
 
 /*
@@ -121,11 +169,58 @@ struct xpc_vars {
 	u64 vars_part_pa;
 	u64 amos_page_pa;	/* paddr of page of AMOs from MSPEC driver */
 	AMO_t *amos_page;	/* vaddr of page of AMOs from MSPEC driver */
-	AMO_t *act_amos;	/* pointer to the first activation AMO */
 };
-#define XPC_V_VERSION _XPC_VERSION(3,0) /* version 3.0 of the cross vars */
 
-#define XPC_VARS_ALIGNED_SIZE  (L1_CACHE_ALIGN(sizeof(struct xpc_vars)))
+#define XPC_V_VERSION _XPC_VERSION(3,1) /* version 3.1 of the cross vars */
+
+#define XPC_SUPPORTS_DISENGAGE_REQUEST(_version) \
+			(_version >= _XPC_VERSION(3,1))
+
+
+static inline int
+xpc_hb_allowed(partid_t partid, struct xpc_vars *vars)
+{
+	return ((vars->heartbeating_to_mask & (1UL << partid)) != 0);
+}
+
+static inline void
+xpc_allow_hb(partid_t partid, struct xpc_vars *vars)
+{
+	u64 old_mask, new_mask;
+
+	do {
+		old_mask = vars->heartbeating_to_mask;
+		new_mask = (old_mask | (1UL << partid));
+	} while (cmpxchg(&vars->heartbeating_to_mask, old_mask, new_mask) !=
+							old_mask);
+}
+
+static inline void
+xpc_disallow_hb(partid_t partid, struct xpc_vars *vars)
+{
+	u64 old_mask, new_mask;
+
+	do {
+		old_mask = vars->heartbeating_to_mask;
+		new_mask = (old_mask & ~(1UL << partid));
+	} while (cmpxchg(&vars->heartbeating_to_mask, old_mask, new_mask) !=
+							old_mask);
+}
+
+
+/*
+ * The AMOs page consists of a number of AMO variables which are divided into
+ * four groups, The first two groups are used to identify an IRQ's sender.
+ * These two groups consist of 64 and 128 AMO variables respectively. The last
+ * two groups, consisting of just one AMO variable each, are used to identify
+ * the remote partitions that are currently engaged (from the viewpoint of
+ * the XPC running on the remote partition).
+ */
+#define XPC_NOTIFY_IRQ_AMOS	   0
+#define XPC_ACTIVATE_IRQ_AMOS	   (XPC_NOTIFY_IRQ_AMOS + XP_MAX_PARTITIONS)
+#define XPC_ENGAGED_PARTITIONS_AMO (XPC_ACTIVATE_IRQ_AMOS + XP_NASID_MASK_WORDS)
+#define XPC_DISENGAGE_REQUEST_AMO  (XPC_ENGAGED_PARTITIONS_AMO + 1)
+
 
 /*
  * The following structure describes the per partition specific variables.
@@ -165,6 +260,16 @@ struct xpc_vars_part {
 #define XPC_VP_MAGIC2	0x0073726176435058L  /* 'XPCvars\0'L (little endian) */
 
 
+/* the reserved page sizes and offsets */
+
+#define XPC_RP_HEADER_SIZE	L1_CACHE_ALIGN(sizeof(struct xpc_rsvd_page))
+#define XPC_RP_VARS_SIZE 	L1_CACHE_ALIGN(sizeof(struct xpc_vars))
+
+#define XPC_RP_PART_NASIDS(_rp) (u64 *) ((u8 *) _rp + XPC_RP_HEADER_SIZE)
+#define XPC_RP_MACH_NASIDS(_rp) (XPC_RP_PART_NASIDS(_rp) + xp_nasid_mask_words)
+#define XPC_RP_VARS(_rp)	((struct xpc_vars *) XPC_RP_MACH_NASIDS(_rp) + xp_nasid_mask_words)
+#define XPC_RP_VARS_PART(_rp)	(struct xpc_vars_part *) ((u8 *) XPC_RP_VARS(rp) + XPC_RP_VARS_SIZE)
+
 
 /*
  * Functions registered by add_timer() or called by kernel_thread() only
@@ -349,6 +454,9 @@ 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 */
@@ -358,7 +466,7 @@ struct xpc_channel {
 	void *key;			/* pointer to user's key */
 
 	struct semaphore msg_to_pull_sema; /* next msg to pull serialization */
-	struct semaphore teardown_sema;    /* wait for teardown completion */
+	struct semaphore wdisconnect_sema; /* wait for channel disconnect */
 
 	struct xpc_openclose_args *local_openclose_args; /* args passed on */
 					/* opening or closing of channel */
@@ -410,6 +518,8 @@ struct xpc_channel {
 
 #define	XPC_C_DISCONNECTED	0x00002000 /* channel is disconnected */
 #define	XPC_C_DISCONNECTING	0x00004000 /* channel is being disconnected */
+#define	XPC_C_DISCONNECTCALLOUT	0x00008000 /* chan disconnected callout made */
+#define	XPC_C_WDISCONNECT	0x00010000 /* waiting for channel disconnect */
 
 
 
@@ -422,6 +532,8 @@ struct xpc_partition {
 
 	/* XPC HB infrastructure */
 
+	u8 remote_rp_version;		/* version# of partition's rsvd pg */
+	struct timespec remote_rp_stamp;/* time when rsvd pg was initialized */
 	u64 remote_rp_pa;		/* phys addr of partition's rsvd pg */
 	u64 remote_vars_pa;		/* phys addr of partition's vars */
 	u64 remote_vars_part_pa;	/* phys addr of partition's vars part */
@@ -432,14 +544,18 @@ struct xpc_partition {
 	u32 act_IRQ_rcvd;		/* IRQs since activation */
 	spinlock_t act_lock;		/* protect updating of act_state */
 	u8 act_state;			/* from XPC HB viewpoint */
+	u8 remote_vars_version;		/* version# of partition's vars */
 	enum xpc_retval reason;		/* reason partition is deactivating */
 	int reason_line;		/* line# deactivation initiated from */
 	int reactivate_nasid;		/* nasid in partition to reactivate */
 
+	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 */
 
@@ -454,6 +570,7 @@ struct xpc_partition {
 
 	u8 nchannels;		   /* #of defined channels supported */
 	atomic_t nchannels_active; /* #of channels that are not DISCONNECTED */
+	atomic_t nchannels_engaged;/* #of channels engaged with remote part */
 	struct xpc_channel *channels;/* array of channel structures */
 
 	void *local_GPs_base;	  /* base address of kmalloc'd space */
@@ -518,6 +635,7 @@ struct xpc_partition {
 #define XPC_P_TORNDOWN		0x03	/* infrastructure is torndown */
 
 
+
 /*
  * struct xpc_partition IPI_timer #of seconds to wait before checking for
  * dropped IPIs. These occur whenever an IPI amo write doesn't complete until
@@ -526,6 +644,13 @@ struct xpc_partition {
 #define XPC_P_DROPPED_IPI_WAIT	(0.25 * HZ)
 
 
+/* number of seconds to wait for other partitions to disengage */
+#define XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT	90
+
+/* interval in seconds to print 'waiting disengagement' messages */
+#define XPC_DISENGAGE_PRINTMSG_INTERVAL		10
+
+
 #define XPC_PARTID(_p)	((partid_t) ((_p) - &xpc_partitions[0]))
 
 
@@ -534,24 +659,20 @@ 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 int xpc_hb_interval;
-extern int xpc_hb_check_interval;
 extern struct xpc_vars *xpc_vars;
 extern struct xpc_rsvd_page *xpc_rsvd_page;
 extern struct xpc_vars_part *xpc_vars_part;
@@ -561,6 +682,7 @@ extern struct xpc_rsvd_page *xpc_rsvd_page_init(void);
 extern void xpc_allow_IPI_ops(void);
 extern void xpc_restrict_IPI_ops(void);
 extern int xpc_identify_act_IRQ_sender(void);
+extern int xpc_partition_disengaged(struct xpc_partition *);
 extern enum xpc_retval xpc_mark_partition_active(struct xpc_partition *);
 extern void xpc_mark_partition_inactive(struct xpc_partition *);
 extern void xpc_discovery(void);
@@ -585,8 +707,8 @@ extern void xpc_connected_callout(struct xpc_channel *);
 extern void xpc_deliver_msg(struct xpc_channel *);
 extern void xpc_disconnect_channel(const int, struct xpc_channel *,
 					enum xpc_retval, unsigned long *);
-extern void xpc_disconnected_callout(struct xpc_channel *);
-extern void xpc_partition_down(struct xpc_partition *, enum xpc_retval);
+extern void xpc_disconnecting_callout(struct xpc_channel *);
+extern void xpc_partition_going_down(struct xpc_partition *, enum xpc_retval);
 extern void xpc_teardown_infrastructure(struct xpc_partition *);
 
 
@@ -674,6 +796,157 @@ xpc_part_ref(struct xpc_partition *part)
 
 
 /*
+ * This next set of inlines are used to keep track of when a partition is
+ * potentially engaged in accessing memory belonging to another partition.
+ */
+
+static inline void
+xpc_mark_partition_engaged(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	AMO_t *amo = (AMO_t *) __va(part->remote_amos_page_pa +
+				(XPC_ENGAGED_PARTITIONS_AMO * sizeof(AMO_t)));
+
+
+	local_irq_save(irq_flags);
+
+	/* set bit corresponding to our partid in remote partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64) &amo->variable), FETCHOP_OR,
+						(1UL << sn_partition_id));
+	/*
+	 * We must always use the nofault function regardless of whether we
+	 * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
+	 * didn't, we'd never know that the other partition is down and would
+	 * keep sending IPIs and AMOs to it until the heartbeat times out.
+	 */
+	(void) xp_nofault_PIOR((u64 *) GLOBAL_MMR_ADDR(NASID_GET(&amo->
+				variable), xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+}
+
+static inline void
+xpc_mark_partition_disengaged(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	AMO_t *amo = (AMO_t *) __va(part->remote_amos_page_pa +
+				(XPC_ENGAGED_PARTITIONS_AMO * sizeof(AMO_t)));
+
+
+	local_irq_save(irq_flags);
+
+	/* clear bit corresponding to our partid in remote partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64) &amo->variable), FETCHOP_AND,
+						~(1UL << sn_partition_id));
+	/*
+	 * We must always use the nofault function regardless of whether we
+	 * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
+	 * didn't, we'd never know that the other partition is down and would
+	 * keep sending IPIs and AMOs to it until the heartbeat times out.
+	 */
+	(void) xp_nofault_PIOR((u64 *) GLOBAL_MMR_ADDR(NASID_GET(&amo->
+				variable), xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+}
+
+static inline void
+xpc_request_partition_disengage(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	AMO_t *amo = (AMO_t *) __va(part->remote_amos_page_pa +
+				(XPC_DISENGAGE_REQUEST_AMO * sizeof(AMO_t)));
+
+
+	local_irq_save(irq_flags);
+
+	/* set bit corresponding to our partid in remote partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64) &amo->variable), FETCHOP_OR,
+						(1UL << sn_partition_id));
+	/*
+	 * We must always use the nofault function regardless of whether we
+	 * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
+	 * didn't, we'd never know that the other partition is down and would
+	 * keep sending IPIs and AMOs to it until the heartbeat times out.
+	 */
+	(void) xp_nofault_PIOR((u64 *) GLOBAL_MMR_ADDR(NASID_GET(&amo->
+				variable), xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+}
+
+static inline void
+xpc_cancel_partition_disengage_request(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	AMO_t *amo = (AMO_t *) __va(part->remote_amos_page_pa +
+				(XPC_DISENGAGE_REQUEST_AMO * sizeof(AMO_t)));
+
+
+	local_irq_save(irq_flags);
+
+	/* clear bit corresponding to our partid in remote partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64) &amo->variable), FETCHOP_AND,
+						~(1UL << sn_partition_id));
+	/*
+	 * We must always use the nofault function regardless of whether we
+	 * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
+	 * didn't, we'd never know that the other partition is down and would
+	 * keep sending IPIs and AMOs to it until the heartbeat times out.
+	 */
+	(void) xp_nofault_PIOR((u64 *) GLOBAL_MMR_ADDR(NASID_GET(&amo->
+				variable), xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+}
+
+static inline u64
+xpc_partition_engaged(u64 partid_mask)
+{
+	AMO_t *amo = xpc_vars->amos_page + XPC_ENGAGED_PARTITIONS_AMO;
+
+
+	/* return our partition's AMO variable ANDed with partid_mask */
+	return (FETCHOP_LOAD_OP(TO_AMO((u64) &amo->variable), FETCHOP_LOAD) &
+								partid_mask);
+}
+
+static inline u64
+xpc_partition_disengage_requested(u64 partid_mask)
+{
+	AMO_t *amo = xpc_vars->amos_page + XPC_DISENGAGE_REQUEST_AMO;
+
+
+	/* return our partition's AMO variable ANDed with partid_mask */
+	return (FETCHOP_LOAD_OP(TO_AMO((u64) &amo->variable), FETCHOP_LOAD) &
+								partid_mask);
+}
+
+static inline void
+xpc_clear_partition_engaged(u64 partid_mask)
+{
+	AMO_t *amo = xpc_vars->amos_page + XPC_ENGAGED_PARTITIONS_AMO;
+
+
+	/* clear bit(s) based on partid_mask in our partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64) &amo->variable), FETCHOP_AND,
+								~partid_mask);
+}
+
+static inline void
+xpc_clear_partition_disengage_request(u64 partid_mask)
+{
+	AMO_t *amo = xpc_vars->amos_page + XPC_DISENGAGE_REQUEST_AMO;
+
+
+	/* clear bit(s) based on partid_mask in our partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64) &amo->variable), FETCHOP_AND,
+								~partid_mask);
+}
+
+
+
+/*
  * The following set of macros and inlines are used for the sending and
  * receiving of IPIs (also known as IRQs). There are two flavors of IPIs,
  * one that is associated with partition activity (SGI_XPC_ACTIVATE) and
@@ -722,13 +995,13 @@ xpc_IPI_send(AMO_t *amo, u64 flag, int nasid, int phys_cpuid, int vector)
  * Flag the appropriate AMO variable and send an IPI to the specified node.
  */
 static inline void
-xpc_activate_IRQ_send(u64 amos_page, int from_nasid, int to_nasid,
+xpc_activate_IRQ_send(u64 amos_page_pa, int from_nasid, int to_nasid,
 			int to_phys_cpuid)
 {
 	int w_index = XPC_NASID_W_INDEX(from_nasid);
 	int b_index = XPC_NASID_B_INDEX(from_nasid);
-	AMO_t *amos = (AMO_t *) __va(amos_page +
-					(XP_MAX_PARTITIONS * sizeof(AMO_t)));
+	AMO_t *amos = (AMO_t *) __va(amos_page_pa +
+				(XPC_ACTIVATE_IRQ_AMOS * sizeof(AMO_t)));
 
 
 	(void) xpc_IPI_send(&amos[w_index], (1UL << b_index), to_nasid,
@@ -756,6 +1029,13 @@ xpc_IPI_send_reactivate(struct xpc_partition *part)
 				xpc_vars->act_nasid, xpc_vars->act_phys_cpuid);
 }
 
+static inline void
+xpc_IPI_send_disengage(struct xpc_partition *part)
+{
+	xpc_activate_IRQ_send(part->remote_amos_page_pa, cnodeid_to_nasid(0),
+			part->remote_act_nasid, part->remote_act_phys_cpuid);
+}
+
 
 /*
  * IPIs associated with SGI_XPC_NOTIFY IRQ.
@@ -836,6 +1116,7 @@ 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)
@@ -903,17 +1184,18 @@ xpc_IPI_send_local_msgrequest(struct xpc_channel *ch)
  * cacheable mapping for the entire region. This will prevent speculative
  * reading of cached copies of our lines from being issued which will cause
  * a PI FSB Protocol error to be generated by the SHUB. For XPC, we need 64
- * (XP_MAX_PARTITIONS) AMO variables for message notification (xpc_main.c)
- * and an additional 16 AMO variables for partition activation (xpc_hb.c).
+ * AMO variables (based on XP_MAX_PARTITIONS) for message notification and an
+ * additional 128 AMO variables (based on XP_NASID_MASK_WORDS) for partition
+ * activation and 2 AMO variables for partition deactivation.
  */
 static inline AMO_t *
-xpc_IPI_init(partid_t partid)
+xpc_IPI_init(int index)
 {
-	AMO_t *part_amo = xpc_vars->amos_page + partid;
+	AMO_t *amo = xpc_vars->amos_page + index;
 
 
-	xpc_IPI_receive(part_amo);
-	return part_amo;
+	(void) xpc_IPI_receive(amo);	/* clear AMO variable */
+	return amo;
 }
 
 
diff --git a/arch/ia64/sn/kernel/xpc_channel.c b/arch/ia64/sn/kernel/xpc_channel.c
index 94698bea7be0..abf4fc2a87bb 100644
--- a/arch/ia64/sn/kernel/xpc_channel.c
+++ b/arch/ia64/sn/kernel/xpc_channel.c
@@ -57,6 +57,7 @@ xpc_initialize_channels(struct xpc_partition *part, partid_t partid)
 
 		spin_lock_init(&ch->lock);
 		sema_init(&ch->msg_to_pull_sema, 1);	/* mutex */
+		sema_init(&ch->wdisconnect_sema, 0);	/* event wait */
 
 		atomic_set(&ch->n_on_msg_allocate_wq, 0);
 		init_waitqueue_head(&ch->msg_allocate_wq);
@@ -166,6 +167,7 @@ xpc_setup_infrastructure(struct xpc_partition *part)
 	xpc_initialize_channels(part, partid);
 
 	atomic_set(&part->nchannels_active, 0);
+	atomic_set(&part->nchannels_engaged, 0);
 
 
 	/* local_IPI_amo were set to 0 by an earlier memset() */
@@ -555,8 +557,6 @@ xpc_allocate_msgqueues(struct xpc_channel *ch)
 		sema_init(&ch->notify_queue[i].sema, 0);
 	}
 
-	sema_init(&ch->teardown_sema, 0);	/* event wait */
-
 	spin_lock_irqsave(&ch->lock, irq_flags);
 	ch->flags |= XPC_C_SETUP;
 	spin_unlock_irqrestore(&ch->lock, irq_flags);
@@ -626,6 +626,55 @@ xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
 
 
 /*
+ * Notify those who wanted to be notified upon delivery of their message.
+ */
+static void
+xpc_notify_senders(struct xpc_channel *ch, enum xpc_retval reason, s64 put)
+{
+	struct xpc_notify *notify;
+	u8 notify_type;
+	s64 get = ch->w_remote_GP.get - 1;
+
+
+	while (++get < put && atomic_read(&ch->n_to_notify) > 0) {
+
+		notify = &ch->notify_queue[get % ch->local_nentries];
+
+		/*
+		 * See if the notify entry indicates it was associated with
+		 * a message who's sender wants to be notified. It is possible
+		 * that it is, but someone else is doing or has done the
+		 * notification.
+		 */
+		notify_type = notify->type;
+		if (notify_type == 0 ||
+				cmpxchg(&notify->type, notify_type, 0) !=
+								notify_type) {
+			continue;
+		}
+
+		DBUG_ON(notify_type != XPC_N_CALL);
+
+		atomic_dec(&ch->n_to_notify);
+
+		if (notify->func != NULL) {
+			dev_dbg(xpc_chan, "notify->func() called, notify=0x%p, "
+				"msg_number=%ld, partid=%d, channel=%d\n",
+				(void *) notify, get, ch->partid, ch->number);
+
+			notify->func(reason, ch->partid, ch->number,
+								notify->key);
+
+			dev_dbg(xpc_chan, "notify->func() returned, "
+				"notify=0x%p, msg_number=%ld, partid=%d, "
+				"channel=%d\n", (void *) notify, get,
+				ch->partid, ch->number);
+		}
+	}
+}
+
+
+/*
  * Free up message queues and other stuff that were allocated for the specified
  * channel.
  *
@@ -669,9 +718,6 @@ xpc_free_msgqueues(struct xpc_channel *ch)
 		ch->remote_msgqueue = NULL;
 		kfree(ch->notify_queue);
 		ch->notify_queue = NULL;
-
-		/* in case someone is waiting for the teardown to complete */
-		up(&ch->teardown_sema);
 	}
 }
 
@@ -683,7 +729,7 @@ static void
 xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
 {
 	struct xpc_partition *part = &xpc_partitions[ch->partid];
-	u32 ch_flags = ch->flags;
+	u32 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);
 
 
 	DBUG_ON(!spin_is_locked(&ch->lock));
@@ -701,12 +747,13 @@ xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
 	}
 	DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
 
-	/* it's now safe to free the channel's message queues */
-
-	xpc_free_msgqueues(ch);
-	DBUG_ON(ch->flags & XPC_C_SETUP);
+	if (part->act_state == XPC_P_DEACTIVATING) {
+		/* can't proceed until the other side disengages from us */
+		if (xpc_partition_engaged(1UL << ch->partid)) {
+			return;
+		}
 
-	if (part->act_state != XPC_P_DEACTIVATING) {
+	} else {
 
 		/* as long as the other side is up do the full protocol */
 
@@ -724,16 +771,42 @@ xpc_process_disconnect(struct xpc_channel *ch, unsigned long *irq_flags)
 		}
 	}
 
+	/* wake those waiting for notify completion */
+	if (atomic_read(&ch->n_to_notify) > 0) {
+		/* >>> we do callout while holding ch->lock */
+		xpc_notify_senders(ch, ch->reason, ch->w_local_GP.put);
+	}
+
 	/* both sides are disconnected now */
 
-	ch->flags = XPC_C_DISCONNECTED;	/* clear all flags, but this one */
+	/* it's now safe to free the channel's message queues */
+	xpc_free_msgqueues(ch);
+
+	/* mark disconnected, clear all other flags except XPC_C_WDISCONNECT */
+	ch->flags = (XPC_C_DISCONNECTED | (ch->flags & XPC_C_WDISCONNECT));
 
 	atomic_dec(&part->nchannels_active);
 
-	if (ch_flags & XPC_C_WASCONNECTED) {
+	if (channel_was_connected) {
 		dev_info(xpc_chan, "channel %d to partition %d disconnected, "
 			"reason=%d\n", ch->number, ch->partid, ch->reason);
 	}
+
+	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;
+	}
 }
 
 
@@ -754,6 +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) {
 
@@ -764,7 +850,7 @@ xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
 		/*
 		 * If RCLOSEREQUEST is set, we're probably waiting for
 		 * RCLOSEREPLY. We should find it and a ROPENREQUEST packed
-		 * with this RCLOSEQREUQEST in the IPI_flags.
+		 * with this RCLOSEREQUEST in the IPI_flags.
 		 */
 
 		if (ch->flags & XPC_C_RCLOSEREQUEST) {
@@ -779,14 +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;
 			}
@@ -816,9 +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);
 	}
 
 
@@ -834,7 +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;
 
@@ -852,8 +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) ||
-					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;
 		}
@@ -867,8 +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;
@@ -906,7 +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);
 
@@ -960,8 +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)) {
@@ -1040,55 +1166,6 @@ xpc_connect_channel(struct xpc_channel *ch)
 
 
 /*
- * Notify those who wanted to be notified upon delivery of their message.
- */
-static void
-xpc_notify_senders(struct xpc_channel *ch, enum xpc_retval reason, s64 put)
-{
-	struct xpc_notify *notify;
-	u8 notify_type;
-	s64 get = ch->w_remote_GP.get - 1;
-
-
-	while (++get < put && atomic_read(&ch->n_to_notify) > 0) {
-
-		notify = &ch->notify_queue[get % ch->local_nentries];
-
-		/*
-		 * See if the notify entry indicates it was associated with
-		 * a message who's sender wants to be notified. It is possible
-		 * that it is, but someone else is doing or has done the
-		 * notification.
-		 */
-		notify_type = notify->type;
-		if (notify_type == 0 ||
-				cmpxchg(&notify->type, notify_type, 0) !=
-								notify_type) {
-			continue;
-		}
-
-		DBUG_ON(notify_type != XPC_N_CALL);
-
-		atomic_dec(&ch->n_to_notify);
-
-		if (notify->func != NULL) {
-			dev_dbg(xpc_chan, "notify->func() called, notify=0x%p, "
-				"msg_number=%ld, partid=%d, channel=%d\n",
-				(void *) notify, get, ch->partid, ch->number);
-
-			notify->func(reason, ch->partid, ch->number,
-								notify->key);
-
-			dev_dbg(xpc_chan, "notify->func() returned, "
-				"notify=0x%p, msg_number=%ld, partid=%d, "
-				"channel=%d\n", (void *) notify, get,
-				ch->partid, ch->number);
-		}
-	}
-}
-
-
-/*
  * Clear some of the msg flags in the local message queue.
  */
 static inline void
@@ -1240,6 +1317,7 @@ xpc_process_channel_activity(struct xpc_partition *part)
 	u64 IPI_amo, IPI_flags;
 	struct xpc_channel *ch;
 	int ch_number;
+	u32 ch_flags;
 
 
 	IPI_amo = xpc_get_IPI_flags(part);
@@ -1266,8 +1344,9 @@ xpc_process_channel_activity(struct xpc_partition *part)
 			xpc_process_openclose_IPI(part, ch_number, IPI_flags);
 		}
 
+		ch_flags = ch->flags;	/* need an atomic snapshot of flags */
 
-		if (ch->flags & XPC_C_DISCONNECTING) {
+		if (ch_flags & XPC_C_DISCONNECTING) {
 			spin_lock_irqsave(&ch->lock, irq_flags);
 			xpc_process_disconnect(ch, &irq_flags);
 			spin_unlock_irqrestore(&ch->lock, irq_flags);
@@ -1278,9 +1357,9 @@ xpc_process_channel_activity(struct xpc_partition *part)
 			continue;
 		}
 
-		if (!(ch->flags & XPC_C_CONNECTED)) {
-			if (!(ch->flags & XPC_C_OPENREQUEST)) {
-				DBUG_ON(ch->flags & XPC_C_SETUP);
+		if (!(ch_flags & XPC_C_CONNECTED)) {
+			if (!(ch_flags & XPC_C_OPENREQUEST)) {
+				DBUG_ON(ch_flags & XPC_C_SETUP);
 				(void) xpc_connect_channel(ch);
 			} else {
 				spin_lock_irqsave(&ch->lock, irq_flags);
@@ -1305,8 +1384,8 @@ xpc_process_channel_activity(struct xpc_partition *part)
 
 
 /*
- * XPC's heartbeat code calls this function to inform XPC that a partition has
- * gone down.  XPC responds by tearing down the XPartition Communication
+ * XPC's heartbeat code calls this function to inform XPC that a partition is
+ * going down.  XPC responds by tearing down the XPartition Communication
  * infrastructure used for the just downed partition.
  *
  * XPC's heartbeat code will never call this function and xpc_partition_up()
@@ -1314,7 +1393,7 @@ xpc_process_channel_activity(struct xpc_partition *part)
  * at the same time.
  */
 void
-xpc_partition_down(struct xpc_partition *part, enum xpc_retval reason)
+xpc_partition_going_down(struct xpc_partition *part, enum xpc_retval reason)
 {
 	unsigned long irq_flags;
 	int ch_number;
@@ -1330,12 +1409,11 @@ xpc_partition_down(struct xpc_partition *part, enum xpc_retval reason)
 	}
 
 
-	/* disconnect all channels associated with the downed partition */
+	/* disconnect channels associated with the partition going down */
 
 	for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
 		ch = &part->channels[ch_number];
 
-
 		xpc_msgqueue_ref(ch);
 		spin_lock_irqsave(&ch->lock, irq_flags);
 
@@ -1370,6 +1448,7 @@ xpc_teardown_infrastructure(struct xpc_partition *part)
 	 * this partition.
 	 */
 
+	DBUG_ON(atomic_read(&part->nchannels_engaged) != 0);
 	DBUG_ON(atomic_read(&part->nchannels_active) != 0);
 	DBUG_ON(part->setup_state != XPC_P_SETUP);
 	part->setup_state = XPC_P_WTEARDOWN;
@@ -1428,19 +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);
 		}
 	}
@@ -1450,9 +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) {
@@ -1465,10 +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);
 }
 
 
@@ -1506,8 +1570,12 @@ xpc_initiate_disconnect(int ch_number)
 
 			spin_lock_irqsave(&ch->lock, irq_flags);
 
-			XPC_DISCONNECT_CHANNEL(ch, xpcUnregistering,
+			if (!(ch->flags & XPC_C_DISCONNECTED)) {
+				ch->flags |= XPC_C_WDISCONNECT;
+
+				XPC_DISCONNECT_CHANNEL(ch, xpcUnregistering,
 								&irq_flags);
+			}
 
 			spin_unlock_irqrestore(&ch->lock, irq_flags);
 
@@ -1523,8 +1591,9 @@ xpc_initiate_disconnect(int ch_number)
 /*
  * To disconnect a channel, and reflect it back to all who may be waiting.
  *
- * >>> An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
- * >>> xpc_free_msgqueues().
+ * An OPEN is not allowed until XPC_C_DISCONNECTING is cleared by
+ * xpc_process_disconnect(), and if set, XPC_C_WDISCONNECT is cleared by
+ * xpc_disconnect_wait().
  *
  * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
  */
@@ -1532,7 +1601,7 @@ void
 xpc_disconnect_channel(const int line, struct xpc_channel *ch,
 			enum xpc_retval reason, unsigned long *irq_flags)
 {
-	u32 flags;
+	u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);
 
 
 	DBUG_ON(!spin_is_locked(&ch->lock));
@@ -1547,61 +1616,53 @@ xpc_disconnect_channel(const int line, struct xpc_channel *ch,
 
 	XPC_SET_REASON(ch, reason, line);
 
-	flags = ch->flags;
+	ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
 	/* some of these may not have been set */
 	ch->flags &= ~(XPC_C_OPENREQUEST | XPC_C_OPENREPLY |
 			XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
 			XPC_C_CONNECTING | XPC_C_CONNECTED);
 
-	ch->flags |= (XPC_C_CLOSEREQUEST | XPC_C_DISCONNECTING);
 	xpc_IPI_send_closerequest(ch, irq_flags);
 
-	if (flags & XPC_C_CONNECTED) {
+	if (channel_was_connected) {
 		ch->flags |= XPC_C_WASCONNECTED;
 	}
 
+	spin_unlock_irqrestore(&ch->lock, *irq_flags);
+
+	/* wake all idle kthreads so they can exit */
 	if (atomic_read(&ch->kthreads_idle) > 0) {
-		/* wake all idle kthreads so they can exit */
 		wake_up_all(&ch->idle_wq);
 	}
 
-	spin_unlock_irqrestore(&ch->lock, *irq_flags);
-
-
 	/* wake those waiting to allocate an entry from the local msg queue */
-
 	if (atomic_read(&ch->n_on_msg_allocate_wq) > 0) {
 		wake_up(&ch->msg_allocate_wq);
 	}
 
-	/* wake those waiting for notify completion */
-
-	if (atomic_read(&ch->n_to_notify) > 0) {
-		xpc_notify_senders(ch, reason, ch->w_local_GP.put);
-	}
-
 	spin_lock_irqsave(&ch->lock, *irq_flags);
 }
 
 
 void
-xpc_disconnected_callout(struct xpc_channel *ch)
+xpc_disconnecting_callout(struct xpc_channel *ch)
 {
 	/*
-	 * Let the channel's registerer know that the channel is now
+	 * Let the channel's registerer know that the channel is being
 	 * disconnected. We don't want to do this if the registerer was never
-	 * informed of a connection being made, unless the disconnect was for
-	 * abnormal reasons.
+	 * informed of a connection being made.
 	 */
 
 	if (ch->func != NULL) {
-		dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
-			"channel=%d\n", ch->reason, ch->partid, ch->number);
+		dev_dbg(xpc_chan, "ch->func() called, reason=xpcDisconnecting,"
+			" partid=%d, channel=%d\n", ch->partid, ch->number);
 
-		ch->func(ch->reason, ch->partid, ch->number, NULL, ch->key);
+		ch->func(xpcDisconnecting, ch->partid, ch->number, NULL,
+								ch->key);
 
-		dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
-			"channel=%d\n", ch->reason, ch->partid, ch->number);
+		dev_dbg(xpc_chan, "ch->func() returned, reason="
+			"xpcDisconnecting, partid=%d, channel=%d\n",
+			ch->partid, ch->number);
 	}
 }
 
@@ -1848,7 +1909,7 @@ xpc_send_msg(struct xpc_channel *ch, struct xpc_msg *msg, u8 notify_type,
 			xpc_notify_func func, void *key)
 {
 	enum xpc_retval ret = xpcSuccess;
-	struct xpc_notify *notify = NULL;   // >>> to keep the compiler happy!!
+	struct xpc_notify *notify = notify;
 	s64 put, msg_number = msg->number;
 
 
diff --git a/arch/ia64/sn/kernel/xpc_main.c b/arch/ia64/sn/kernel/xpc_main.c
index ed7c21586e98..cece3c7c69be 100644
--- a/arch/ia64/sn/kernel/xpc_main.c
+++ b/arch/ia64/sn/kernel/xpc_main.c
@@ -54,6 +54,7 @@
 #include <linux/interrupt.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
+#include <linux/reboot.h>
 #include <asm/sn/intr.h>
 #include <asm/sn/sn_sal.h>
 #include <asm/uaccess.h>
@@ -82,11 +83,17 @@ 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_interval = XPC_HB_DEFAULT_INTERVAL;
+static int xpc_hb_min_interval = 1;
+static int xpc_hb_max_interval = 10;
 
-static int xpc_hb_check_min = 10;
-static int xpc_hb_check_max = 120;
+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[] = {
 	{
@@ -99,7 +106,8 @@ static ctl_table xpc_sys_xpc_hb_dir[] = {
 		&proc_dointvec_minmax,
 		&sysctl_intvec,
 		NULL,
-		&xpc_hb_min, &xpc_hb_max
+		&xpc_hb_min_interval,
+		&xpc_hb_max_interval
 	},
 	{
 		2,
@@ -111,7 +119,8 @@ static ctl_table xpc_sys_xpc_hb_dir[] = {
 		&proc_dointvec_minmax,
 		&sysctl_intvec,
 		NULL,
-		&xpc_hb_check_min, &xpc_hb_check_max
+		&xpc_hb_check_min_interval,
+		&xpc_hb_check_max_interval
 	},
 	{0}
 };
@@ -124,6 +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[] = {
@@ -148,10 +170,10 @@ static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
 
 static unsigned long xpc_hb_check_timeout;
 
-/* xpc_hb_checker thread exited notification */
+/* notification that the xpc_hb_checker thread has exited */
 static DECLARE_MUTEX_LOCKED(xpc_hb_checker_exited);
 
-/* xpc_discovery thread exited notification */
+/* notification that the xpc_discovery thread has exited */
 static DECLARE_MUTEX_LOCKED(xpc_discovery_exited);
 
 
@@ -161,6 +183,30 @@ static struct timer_list xpc_hb_timer;
 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,
+};
+
+
+/*
+ * Timer function to enforce the timelimit on the partition disengage request.
+ */
+static void
+xpc_timeout_partition_disengage_request(unsigned long data)
+{
+	struct xpc_partition *part = (struct xpc_partition *) data;
+
+
+	DBUG_ON(jiffies < part->disengage_request_timeout);
+
+	(void) xpc_partition_disengaged(part);
+
+	DBUG_ON(part->disengage_request_timeout != 0);
+	DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
+}
+
+
 /*
  * Notify the heartbeat check thread that an IRQ has been received.
  */
@@ -214,12 +260,6 @@ xpc_hb_checker(void *ignore)
 
 	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),
@@ -240,6 +280,7 @@ xpc_hb_checker(void *ignore)
 		}
 
 
+		/* check for outstanding IRQs */
 		new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
 		if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
 			force_IRQ = 0;
@@ -257,12 +298,18 @@ xpc_hb_checker(void *ignore)
 			xpc_hb_check_timeout = jiffies +
 					   (xpc_hb_check_interval * HZ);
 		}
+
+		/* 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, "heartbeat checker is exiting\n");
 
 
-	/* mark this thread as inactive */
+	/* mark this thread as having exited */
 	up(&xpc_hb_checker_exited);
 	return 0;
 }
@@ -282,7 +329,7 @@ xpc_initiate_discovery(void *ignore)
 
 	dev_dbg(xpc_part, "discovery thread is exiting\n");
 
-	/* mark this thread as inactive */
+	/* mark this thread as having exited */
 	up(&xpc_discovery_exited);
 	return 0;
 }
@@ -309,7 +356,7 @@ xpc_make_first_contact(struct xpc_partition *part)
 			"partition %d\n", XPC_PARTID(part));
 
 		/* wait a 1/4 of a second or so */
-		msleep_interruptible(250);
+		(void) msleep_interruptible(250);
 
 		if (part->act_state == XPC_P_DEACTIVATING) {
 			return part->reason;
@@ -336,7 +383,8 @@ static void
 xpc_channel_mgr(struct xpc_partition *part)
 {
 	while (part->act_state != XPC_P_DEACTIVATING ||
-				atomic_read(&part->nchannels_active) > 0) {
+			atomic_read(&part->nchannels_active) > 0 ||
+					!xpc_partition_disengaged(part)) {
 
 		xpc_process_channel_activity(part);
 
@@ -360,7 +408,8 @@ xpc_channel_mgr(struct xpc_partition *part)
 				(volatile u64) part->local_IPI_amo != 0 ||
 				((volatile u8) part->act_state ==
 							XPC_P_DEACTIVATING &&
-				atomic_read(&part->nchannels_active) == 0)));
+				atomic_read(&part->nchannels_active) == 0 &&
+				xpc_partition_disengaged(part))));
 		atomic_set(&part->channel_mgr_requests, 1);
 
 		// >>> Does it need to wakeup periodically as well? In case we
@@ -482,7 +531,7 @@ xpc_activating(void *__partid)
 		return 0;
 	}
 
-	XPC_ALLOW_HB(partid, xpc_vars);
+	xpc_allow_hb(partid, xpc_vars);
 	xpc_IPI_send_activated(part);
 
 
@@ -492,6 +541,7 @@ xpc_activating(void *__partid)
 	 */
 	(void) xpc_partition_up(part);
 
+	xpc_disallow_hb(partid, xpc_vars);
 	xpc_mark_partition_inactive(part);
 
 	if (part->reason == xpcReactivating) {
@@ -670,6 +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);
@@ -680,11 +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);
 
 			/*
@@ -699,16 +753,28 @@ 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 &&
-			((ch->flags & XPC_C_CONNECTCALLOUT) ||
-				(ch->reason != xpcUnregistering &&
-					ch->reason != xpcOtherUnregistering))) {
-		xpc_disconnected_callout(ch);
+	if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
+		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);
+			xpc_IPI_send_disengage(part);
+		}
 	}
 
 
@@ -740,12 +806,33 @@ 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);
+	struct xpc_partition *part = &xpc_partitions[ch->partid];
 
 
 	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) {
@@ -765,14 +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(&xpc_partitions[ch->partid]);
-		xpc_msgqueue_ref(ch);
-		atomic_inc(&ch->kthreads_assigned);
 		ch->kthreads_created++;	// >>> temporary debug only!!!
 	}
 }
@@ -781,87 +860,142 @@ xpc_create_kthreads(struct xpc_channel *ch, int needed)
 void
 xpc_disconnect_wait(int ch_number)
 {
+	unsigned long irq_flags;
 	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;
+		}
 
-// >>> 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);
-			}
+		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);
 	}
 }
 
 
 static void
-xpc_do_exit(void)
+xpc_do_exit(enum xpc_retval reason)
 {
 	partid_t partid;
 	int active_part_count;
 	struct xpc_partition *part;
+	unsigned long printmsg_time;
 
 
-	/* 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);
+	/* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
+	DBUG_ON(xpc_exiting == 1);
 
 	/*
-	 * 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.
+	 * 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_act_IRQ_wq);
 
-	/* wait for the heartbeat checker thread to mark itself inactive */
-	down(&xpc_hb_checker_exited);
+	/* ignore all incoming interrupts */
+	free_irq(SGI_XPC_ACTIVATE, NULL);
 
-	/* wait for the discovery thread to mark itself inactive */
+	/* wait for the discovery thread to exit */
 	down(&xpc_discovery_exited);
 
+	/* wait for the heartbeat checker thread to exit */
+	down(&xpc_hb_checker_exited);
 
-	msleep_interruptible(300);
+
+	/* sleep for a 1/3 of a second or so */
+	(void) msleep_interruptible(300);
 
 
 	/* wait for all partitions to become inactive */
 
+	printmsg_time = jiffies;
+
 	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 (xpc_partition_disengaged(part) &&
+					part->act_state == XPC_P_INACTIVE) {
+				continue;
 			}
+
+			active_part_count++;
+
+			XPC_DEACTIVATE_PARTITION(part, reason);
 		}
 
-		if (active_part_count)
-			msleep_interruptible(300);
-	} while (active_part_count > 0);
+		if (active_part_count == 0) {
+			break;
+		}
 
+		if (jiffies >= printmsg_time) {
+			dev_info(xpc_part, "waiting for partitions to "
+				"deactivate/disengage, active count=%d, remote "
+				"engaged=0x%lx\n", active_part_count,
+				xpc_partition_engaged(1UL << partid));
+
+			printmsg_time = jiffies +
+					(XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
+		}
+
+		/* sleep for a 1/3 of a second or so */
+		(void) msleep_interruptible(300);
+
+	} while (1);
+
+	DBUG_ON(xpc_partition_engaged(-1UL));
+
+
+	/* indicate to others that our reserved page is uninitialized */
+	xpc_rsvd_page->vars_pa = 0;
+
+	/* now it's time to eliminate our heartbeat */
+	del_timer_sync(&xpc_hb_timer);
+	DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
+
+	/* take ourselves off of the reboot_notifier_list */
+	(void) unregister_reboot_notifier(&xpc_reboot_notifier);
 
 	/* close down protections for IPI operations */
 	xpc_restrict_IPI_ops();
@@ -876,6 +1010,34 @@ xpc_do_exit(void)
 }
 
 
+/*
+ * 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 xpc_retval reason;
+
+
+	switch (event) {
+	case SYS_RESTART:
+		reason = xpcSystemReboot;
+		break;
+	case SYS_HALT:
+		reason = xpcSystemHalt;
+		break;
+	case SYS_POWER_OFF:
+		reason = xpcSystemPoweroff;
+		break;
+	default:
+		reason = xpcSystemGoingDown;
+	}
+
+	xpc_do_exit(reason);
+	return NOTIFY_DONE;
+}
+
+
 int __init
 xpc_init(void)
 {
@@ -891,11 +1053,11 @@ xpc_init(void)
 
 	/*
 	 * 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.
+	 * various portions of a partition's reserved page. Its size is based
+	 * on the size of the reserved page header and part_nasids mask. So we
+	 * need to ensure that the other items will fit as well.
 	 */
-	if (XPC_VARS_ALIGNED_SIZE > XPC_RSVD_PAGE_ALIGNED_SIZE) {
+	if (XPC_RP_VARS_SIZE > XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES) {
 		dev_err(xpc_part, "xpc_remote_copy_buffer is not big enough\n");
 		return -EPERM;
 	}
@@ -924,6 +1086,12 @@ xpc_init(void)
 		spin_lock_init(&part->act_lock);
 		part->act_state = XPC_P_INACTIVE;
 		XPC_SET_REASON(part, 0, 0);
+
+		init_timer(&part->disengage_request_timer);
+		part->disengage_request_timer.function =
+				xpc_timeout_partition_disengage_request;
+		part->disengage_request_timer.data = (unsigned long) part;
+
 		part->setup_state = XPC_P_UNSET;
 		init_waitqueue_head(&part->teardown_wq);
 		atomic_set(&part->references, 0);
@@ -980,6 +1148,13 @@ xpc_init(void)
 	}
 
 
+	/* 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");
+	}
+
+
 	/*
 	 * Set the beating to other partitions into motion.  This is
 	 * the last requirement for other partitions' discovery to
@@ -1001,6 +1176,9 @@ xpc_init(void)
 		/* indicate to others that our reserved page is uninitialized */
 		xpc_rsvd_page->vars_pa = 0;
 
+		/* take ourselves off of the reboot_notifier_list */
+		(void) unregister_reboot_notifier(&xpc_reboot_notifier);
+
 		del_timer_sync(&xpc_hb_timer);
 		free_irq(SGI_XPC_ACTIVATE, NULL);
 		xpc_restrict_IPI_ops();
@@ -1024,7 +1202,7 @@ xpc_init(void)
 		/* mark this new thread as a non-starter */
 		up(&xpc_discovery_exited);
 
-		xpc_do_exit();
+		xpc_do_exit(xpcUnloading);
 		return -EBUSY;
 	}
 
@@ -1043,7 +1221,7 @@ module_init(xpc_init);
 void __exit
 xpc_exit(void)
 {
-	xpc_do_exit();
+	xpc_do_exit(xpcUnloading);
 }
 module_exit(xpc_exit);
 
@@ -1060,3 +1238,7 @@ 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 72ef330fb784..581e113d2d37 100644
--- a/arch/ia64/sn/kernel/xpc_partition.c
+++ b/arch/ia64/sn/kernel/xpc_partition.c
@@ -47,13 +47,16 @@ static u64 xpc_sh2_IPI_access3;
 u64 xpc_prot_vec[MAX_NUMNODES];
 
 
-/* this partition's reserved page */
+/* this partition's reserved page pointers */
 struct xpc_rsvd_page *xpc_rsvd_page;
-
-/* this partition's XPC variables (within the reserved page) */
+static u64 *xpc_part_nasids;
+static u64 *xpc_mach_nasids;
 struct xpc_vars *xpc_vars;
 struct xpc_vars_part *xpc_vars_part;
 
+static int xp_nasid_mask_bytes;	/* actual size in bytes of nasid mask */
+static int xp_nasid_mask_words;	/* actual size in words of nasid mask */
+
 
 /*
  * For performance reasons, each entry of xpc_partitions[] is cacheline
@@ -65,20 +68,16 @@ struct xpc_partition xpc_partitions[XP_MAX_PARTITIONS + 1];
 
 
 /*
- * Generic buffer used to store a local copy of the remote partitions
- * reserved page or XPC variables.
+ * Generic buffer used to store a local copy of portions of a remote
+ * partition's reserved page (either its header and part_nasids mask,
+ * or its vars).
  *
  * xpc_discovery runs only once and is a seperate thread that is
  * very likely going to be processing in parallel with receiving
  * interrupts.
  */
-char ____cacheline_aligned
-		xpc_remote_copy_buffer[XPC_RSVD_PAGE_ALIGNED_SIZE];
-
-
-/* systune related variables */
-int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
-int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_TIMEOUT;
+char ____cacheline_aligned xpc_remote_copy_buffer[XPC_RP_HEADER_SIZE +
+							XP_NASID_MASK_BYTES];
 
 
 /*
@@ -86,13 +85,16 @@ int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_TIMEOUT;
  * for that nasid. This function returns 0 on any error.
  */
 static u64
-xpc_get_rsvd_page_pa(int nasid, u64 buf, u64 buf_size)
+xpc_get_rsvd_page_pa(int nasid)
 {
 	bte_result_t bte_res;
 	s64 status;
 	u64 cookie = 0;
 	u64 rp_pa = nasid;	/* seed with nasid */
 	u64 len = 0;
+	u64 buf = buf;
+	u64 buf_len = 0;
+	void *buf_base = NULL;
 
 
 	while (1) {
@@ -108,13 +110,22 @@ xpc_get_rsvd_page_pa(int nasid, u64 buf, u64 buf_size)
 			break;
 		}
 
-		if (len > buf_size) {
-			dev_err(xpc_part, "len (=0x%016lx) > buf_size\n", len);
-			status = SALRET_ERROR;
-			break;
+		if (L1_CACHE_ALIGN(len) > buf_len) {
+			if (buf_base != NULL) {
+				kfree(buf_base);
+			}
+			buf_len = L1_CACHE_ALIGN(len);
+			buf = (u64) xpc_kmalloc_cacheline_aligned(buf_len,
+							GFP_KERNEL, &buf_base);
+			if (buf_base == NULL) {
+				dev_err(xpc_part, "unable to kmalloc "
+					"len=0x%016lx\n", buf_len);
+				status = SALRET_ERROR;
+				break;
+			}
 		}
 
-		bte_res = xp_bte_copy(rp_pa, ia64_tpa(buf), buf_size,
+		bte_res = xp_bte_copy(rp_pa, ia64_tpa(buf), buf_len,
 					(BTE_NOTIFY | BTE_WACQUIRE), NULL);
 		if (bte_res != BTE_SUCCESS) {
 			dev_dbg(xpc_part, "xp_bte_copy failed %i\n", bte_res);
@@ -123,6 +134,10 @@ xpc_get_rsvd_page_pa(int nasid, u64 buf, u64 buf_size)
 		}
 	}
 
+	if (buf_base != NULL) {
+		kfree(buf_base);
+	}
+
 	if (status != SALRET_OK) {
 		rp_pa = 0;
 	}
@@ -141,15 +156,15 @@ xpc_rsvd_page_init(void)
 {
 	struct xpc_rsvd_page *rp;
 	AMO_t *amos_page;
-	u64 rp_pa, next_cl, nasid_array = 0;
+	u64 rp_pa, nasid_array = 0;
 	int i, ret;
 
 
 	/* get the local reserved page's address */
 
-	rp_pa = xpc_get_rsvd_page_pa(cnodeid_to_nasid(0),
-					(u64) xpc_remote_copy_buffer,
-						XPC_RSVD_PAGE_ALIGNED_SIZE);
+	preempt_disable();
+	rp_pa = xpc_get_rsvd_page_pa(cpuid_to_nasid(smp_processor_id()));
+	preempt_enable();
 	if (rp_pa == 0) {
 		dev_err(xpc_part, "SAL failed to locate the reserved page\n");
 		return NULL;
@@ -164,12 +179,19 @@ xpc_rsvd_page_init(void)
 
 	rp->version = XPC_RP_VERSION;
 
-	/*
-	 * Place the XPC variables on the cache line following the
-	 * reserved page structure.
-	 */
-	next_cl = (u64) rp + XPC_RSVD_PAGE_ALIGNED_SIZE;
-	xpc_vars = (struct xpc_vars *) next_cl;
+	/* establish the actual sizes of the nasid masks */
+	if (rp->SAL_version == 1) {
+		/* SAL_version 1 didn't set the nasids_size field */
+		rp->nasids_size = 128;
+	}
+	xp_nasid_mask_bytes = rp->nasids_size;
+	xp_nasid_mask_words = xp_nasid_mask_bytes / 8;
+
+	/* setup the pointers to the various items in the reserved page */
+	xpc_part_nasids = XPC_RP_PART_NASIDS(rp);
+	xpc_mach_nasids = XPC_RP_MACH_NASIDS(rp);
+	xpc_vars = XPC_RP_VARS(rp);
+	xpc_vars_part = XPC_RP_VARS_PART(rp);
 
 	/*
 	 * Before clearing xpc_vars, see if a page of AMOs had been previously
@@ -221,33 +243,32 @@ xpc_rsvd_page_init(void)
 		amos_page = (AMO_t *) TO_AMO((u64) amos_page);
 	}
 
+	/* clear xpc_vars */
 	memset(xpc_vars, 0, sizeof(struct xpc_vars));
 
-	/*
-	 * Place the XPC per partition specific variables on the cache line
-	 * following the XPC variables structure.
-	 */
-	next_cl += XPC_VARS_ALIGNED_SIZE;
-	memset((u64 *) next_cl, 0, sizeof(struct xpc_vars_part) *
-							XP_MAX_PARTITIONS);
-	xpc_vars_part = (struct xpc_vars_part *) next_cl;
-	xpc_vars->vars_part_pa = __pa(next_cl);
-
 	xpc_vars->version = XPC_V_VERSION;
 	xpc_vars->act_nasid = cpuid_to_nasid(0);
 	xpc_vars->act_phys_cpuid = cpu_physical_id(0);
+	xpc_vars->vars_part_pa = __pa(xpc_vars_part);
+	xpc_vars->amos_page_pa = ia64_tpa((u64) amos_page);
 	xpc_vars->amos_page = amos_page;  /* save for next load of XPC */
 
 
-	/*
-	 * Initialize the activation related AMO variables.
-	 */
-	xpc_vars->act_amos = xpc_IPI_init(XP_MAX_PARTITIONS);
-	for (i = 1; i < XP_NASID_MASK_WORDS; i++) {
-		xpc_IPI_init(i + XP_MAX_PARTITIONS);
+	/* clear xpc_vars_part */
+	memset((u64 *) xpc_vars_part, 0, sizeof(struct xpc_vars_part) *
+							XP_MAX_PARTITIONS);
+
+	/* initialize the activate IRQ related AMO variables */
+	for (i = 0; i < xp_nasid_mask_words; i++) {
+		(void) xpc_IPI_init(XPC_ACTIVATE_IRQ_AMOS + i);
 	}
-	/* export AMO page's physical address to other partitions */
-	xpc_vars->amos_page_pa = ia64_tpa((u64) xpc_vars->amos_page);
+
+	/* initialize the engaged remote partitions related AMO variables */
+	(void) xpc_IPI_init(XPC_ENGAGED_PARTITIONS_AMO);
+	(void) xpc_IPI_init(XPC_DISENGAGE_REQUEST_AMO);
+
+	/* timestamp of when reserved page was setup by XPC */
+	rp->stamp = CURRENT_TIME;
 
 	/*
 	 * This signifies to the remote partition that our reserved
@@ -387,6 +408,11 @@ xpc_check_remote_hb(void)
 	remote_vars = (struct xpc_vars *) xpc_remote_copy_buffer;
 
 	for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
+
+		if (xpc_exiting) {
+			break;
+		}
+
 		if (partid == sn_partition_id) {
 			continue;
 		}
@@ -401,7 +427,7 @@ xpc_check_remote_hb(void)
 		/* pull the remote_hb cache line */
 		bres = xp_bte_copy(part->remote_vars_pa,
 					ia64_tpa((u64) remote_vars),
-					XPC_VARS_ALIGNED_SIZE,
+					XPC_RP_VARS_SIZE,
 					(BTE_NOTIFY | BTE_WACQUIRE), NULL);
 		if (bres != BTE_SUCCESS) {
 			XPC_DEACTIVATE_PARTITION(part,
@@ -417,7 +443,7 @@ xpc_check_remote_hb(void)
 
 		if (((remote_vars->heartbeat == part->last_heartbeat) &&
 			(remote_vars->kdb_status == 0)) ||
-			     !XPC_HB_ALLOWED(sn_partition_id, remote_vars)) {
+			     !xpc_hb_allowed(sn_partition_id, remote_vars)) {
 
 			XPC_DEACTIVATE_PARTITION(part, xpcNoHeartbeat);
 			continue;
@@ -429,31 +455,31 @@ xpc_check_remote_hb(void)
 
 
 /*
- * Get a copy of the remote partition's rsvd page.
+ * Get a copy of a portion of the remote partition's rsvd page.
  *
  * remote_rp points to a buffer that is cacheline aligned for BTE copies and
- * assumed to be of size XPC_RSVD_PAGE_ALIGNED_SIZE.
+ * is large enough to contain a copy of their reserved page header and
+ * part_nasids mask.
  */
 static enum xpc_retval
 xpc_get_remote_rp(int nasid, u64 *discovered_nasids,
-		struct xpc_rsvd_page *remote_rp, u64 *remote_rsvd_page_pa)
+		struct xpc_rsvd_page *remote_rp, u64 *remote_rp_pa)
 {
 	int bres, i;
 
 
 	/* get the reserved page's physical address */
 
-	*remote_rsvd_page_pa = xpc_get_rsvd_page_pa(nasid, (u64) remote_rp,
-						XPC_RSVD_PAGE_ALIGNED_SIZE);
-	if (*remote_rsvd_page_pa == 0) {
+	*remote_rp_pa = xpc_get_rsvd_page_pa(nasid);
+	if (*remote_rp_pa == 0) {
 		return xpcNoRsvdPageAddr;
 	}
 
 
-	/* pull over the reserved page structure */
+	/* pull over the reserved page header and part_nasids mask */
 
-	bres = xp_bte_copy(*remote_rsvd_page_pa, ia64_tpa((u64) remote_rp),
-				XPC_RSVD_PAGE_ALIGNED_SIZE,
+	bres = xp_bte_copy(*remote_rp_pa, ia64_tpa((u64) remote_rp),
+				XPC_RP_HEADER_SIZE + xp_nasid_mask_bytes,
 				(BTE_NOTIFY | BTE_WACQUIRE), NULL);
 	if (bres != BTE_SUCCESS) {
 		return xpc_map_bte_errors(bres);
@@ -461,8 +487,11 @@ xpc_get_remote_rp(int nasid, u64 *discovered_nasids,
 
 
 	if (discovered_nasids != NULL) {
-		for (i = 0; i < XP_NASID_MASK_WORDS; i++) {
-			discovered_nasids[i] |= remote_rp->part_nasids[i];
+		u64 *remote_part_nasids = XPC_RP_PART_NASIDS(remote_rp);
+
+
+		for (i = 0; i < xp_nasid_mask_words; i++) {
+			discovered_nasids[i] |= remote_part_nasids[i];
 		}
 	}
 
@@ -489,10 +518,10 @@ xpc_get_remote_rp(int nasid, u64 *discovered_nasids,
 
 
 /*
- * Get a copy of the remote partition's XPC variables.
+ * Get a copy of the remote partition's XPC variables from the reserved page.
  *
  * remote_vars points to a buffer that is cacheline aligned for BTE copies and
- * assumed to be of size XPC_VARS_ALIGNED_SIZE.
+ * assumed to be of size XPC_RP_VARS_SIZE.
  */
 static enum xpc_retval
 xpc_get_remote_vars(u64 remote_vars_pa, struct xpc_vars *remote_vars)
@@ -508,7 +537,7 @@ xpc_get_remote_vars(u64 remote_vars_pa, struct xpc_vars *remote_vars)
 	/* pull over the cross partition variables */
 
 	bres = xp_bte_copy(remote_vars_pa, ia64_tpa((u64) remote_vars),
-				XPC_VARS_ALIGNED_SIZE,
+				XPC_RP_VARS_SIZE,
 				(BTE_NOTIFY | BTE_WACQUIRE), NULL);
 	if (bres != BTE_SUCCESS) {
 		return xpc_map_bte_errors(bres);
@@ -524,7 +553,56 @@ xpc_get_remote_vars(u64 remote_vars_pa, struct xpc_vars *remote_vars)
 
 
 /*
- * Prior code has determine the nasid which generated an IPI.  Inspect
+ * Update the remote partition's info.
+ */
+static void
+xpc_update_partition_info(struct xpc_partition *part, u8 remote_rp_version,
+		struct timespec *remote_rp_stamp, u64 remote_rp_pa,
+		u64 remote_vars_pa, struct xpc_vars *remote_vars)
+{
+	part->remote_rp_version = remote_rp_version;
+	dev_dbg(xpc_part, "  remote_rp_version = 0x%016lx\n",
+		part->remote_rp_version);
+
+	part->remote_rp_stamp = *remote_rp_stamp;
+	dev_dbg(xpc_part, "  remote_rp_stamp (tv_sec = 0x%lx tv_nsec = 0x%lx\n",
+		part->remote_rp_stamp.tv_sec, part->remote_rp_stamp.tv_nsec);
+
+	part->remote_rp_pa = remote_rp_pa;
+	dev_dbg(xpc_part, "  remote_rp_pa = 0x%016lx\n", part->remote_rp_pa);
+
+	part->remote_vars_pa = remote_vars_pa;
+	dev_dbg(xpc_part, "  remote_vars_pa = 0x%016lx\n",
+		part->remote_vars_pa);
+
+	part->last_heartbeat = remote_vars->heartbeat;
+	dev_dbg(xpc_part, "  last_heartbeat = 0x%016lx\n",
+		part->last_heartbeat);
+
+	part->remote_vars_part_pa = remote_vars->vars_part_pa;
+	dev_dbg(xpc_part, "  remote_vars_part_pa = 0x%016lx\n",
+		part->remote_vars_part_pa);
+
+	part->remote_act_nasid = remote_vars->act_nasid;
+	dev_dbg(xpc_part, "  remote_act_nasid = 0x%x\n",
+		part->remote_act_nasid);
+
+	part->remote_act_phys_cpuid = remote_vars->act_phys_cpuid;
+	dev_dbg(xpc_part, "  remote_act_phys_cpuid = 0x%x\n",
+		part->remote_act_phys_cpuid);
+
+	part->remote_amos_page_pa = remote_vars->amos_page_pa;
+	dev_dbg(xpc_part, "  remote_amos_page_pa = 0x%lx\n",
+		part->remote_amos_page_pa);
+
+	part->remote_vars_version = remote_vars->version;
+	dev_dbg(xpc_part, "  remote_vars_version = 0x%x\n",
+		part->remote_vars_version);
+}
+
+
+/*
+ * Prior code has determined the nasid which generated an IPI.  Inspect
  * that nasid to determine if its partition needs to be activated or
  * deactivated.
  *
@@ -542,8 +620,12 @@ xpc_identify_act_IRQ_req(int nasid)
 {
 	struct xpc_rsvd_page *remote_rp;
 	struct xpc_vars *remote_vars;
-	u64 remote_rsvd_page_pa;
+	u64 remote_rp_pa;
 	u64 remote_vars_pa;
+	int remote_rp_version;
+	int reactivate = 0;
+	int stamp_diff;
+	struct timespec remote_rp_stamp = { 0, 0 };
 	partid_t partid;
 	struct xpc_partition *part;
 	enum xpc_retval ret;
@@ -553,7 +635,7 @@ xpc_identify_act_IRQ_req(int nasid)
 
 	remote_rp = (struct xpc_rsvd_page *) xpc_remote_copy_buffer;
 
-	ret = xpc_get_remote_rp(nasid, NULL, remote_rp, &remote_rsvd_page_pa);
+	ret = xpc_get_remote_rp(nasid, NULL, remote_rp, &remote_rp_pa);
 	if (ret != xpcSuccess) {
 		dev_warn(xpc_part, "unable to get reserved page from nasid %d, "
 			"which sent interrupt, reason=%d\n", nasid, ret);
@@ -561,6 +643,10 @@ xpc_identify_act_IRQ_req(int nasid)
 	}
 
 	remote_vars_pa = remote_rp->vars_pa;
+	remote_rp_version = remote_rp->version;
+	if (XPC_SUPPORTS_RP_STAMP(remote_rp_version)) {
+		remote_rp_stamp = remote_rp->stamp;
+	}
 	partid = remote_rp->partid;
 	part = &xpc_partitions[partid];
 
@@ -586,44 +672,117 @@ xpc_identify_act_IRQ_req(int nasid)
 		"%ld:0x%lx\n", (int) nasid, (int) partid, part->act_IRQ_rcvd,
 		remote_vars->heartbeat, remote_vars->heartbeating_to_mask);
 
+	if (xpc_partition_disengaged(part) &&
+					part->act_state == XPC_P_INACTIVE) {
 
-	if (part->act_state == XPC_P_INACTIVE) {
+		xpc_update_partition_info(part, remote_rp_version,
+					&remote_rp_stamp, remote_rp_pa,
+					remote_vars_pa, remote_vars);
 
-		part->remote_rp_pa = remote_rsvd_page_pa;
-		dev_dbg(xpc_part, "  remote_rp_pa = 0x%016lx\n",
-			part->remote_rp_pa);
+		if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
+			if (xpc_partition_disengage_requested(1UL << partid)) {
+				/*
+				 * Other side is waiting on us to disengage,
+				 * even though we already have.
+				 */
+				return;
+			}
+		} else {
+			/* other side doesn't support disengage requests */
+			xpc_clear_partition_disengage_request(1UL << partid);
+		}
 
-		part->remote_vars_pa = remote_vars_pa;
-		dev_dbg(xpc_part, "  remote_vars_pa = 0x%016lx\n",
-			part->remote_vars_pa);
+		xpc_activate_partition(part);
+		return;
+	}
 
-		part->last_heartbeat = remote_vars->heartbeat;
-		dev_dbg(xpc_part, "  last_heartbeat = 0x%016lx\n",
-			part->last_heartbeat);
+	DBUG_ON(part->remote_rp_version == 0);
+	DBUG_ON(part->remote_vars_version == 0);
+
+	if (!XPC_SUPPORTS_RP_STAMP(part->remote_rp_version)) {
+		DBUG_ON(XPC_SUPPORTS_DISENGAGE_REQUEST(part->
+							remote_vars_version));
+
+		if (!XPC_SUPPORTS_RP_STAMP(remote_rp_version)) {
+			DBUG_ON(XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->
+								version));
+			/* see if the other side rebooted */
+			if (part->remote_amos_page_pa ==
+				remote_vars->amos_page_pa &&
+					xpc_hb_allowed(sn_partition_id,
+								remote_vars)) {
+				/* doesn't look that way, so ignore the IPI */
+				return;
+			}
+		}
 
-		part->remote_vars_part_pa = remote_vars->vars_part_pa;
-		dev_dbg(xpc_part, "  remote_vars_part_pa = 0x%016lx\n",
-			part->remote_vars_part_pa);
+		/*
+		 * Other side rebooted and previous XPC didn't support the
+		 * disengage request, so we don't need to do anything special.
+		 */
 
-		part->remote_act_nasid = remote_vars->act_nasid;
-		dev_dbg(xpc_part, "  remote_act_nasid = 0x%x\n",
-			part->remote_act_nasid);
+		xpc_update_partition_info(part, remote_rp_version,
+						&remote_rp_stamp, remote_rp_pa,
+						remote_vars_pa, remote_vars);
+		part->reactivate_nasid = nasid;
+		XPC_DEACTIVATE_PARTITION(part, xpcReactivating);
+		return;
+	}
 
-		part->remote_act_phys_cpuid = remote_vars->act_phys_cpuid;
-		dev_dbg(xpc_part, "  remote_act_phys_cpuid = 0x%x\n",
-			part->remote_act_phys_cpuid);
+	DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version));
 
-		part->remote_amos_page_pa = remote_vars->amos_page_pa;
-		dev_dbg(xpc_part, "  remote_amos_page_pa = 0x%lx\n",
-			part->remote_amos_page_pa);
+	if (!XPC_SUPPORTS_RP_STAMP(remote_rp_version)) {
+		DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->version));
 
-		xpc_activate_partition(part);
+		/*
+		 * Other side rebooted and previous XPC did support the
+		 * disengage request, but the new one doesn't.
+		 */
+
+		xpc_clear_partition_engaged(1UL << partid);
+		xpc_clear_partition_disengage_request(1UL << partid);
 
-	} else if (part->remote_amos_page_pa != remote_vars->amos_page_pa ||
-			!XPC_HB_ALLOWED(sn_partition_id, remote_vars)) {
+		xpc_update_partition_info(part, remote_rp_version,
+						&remote_rp_stamp, remote_rp_pa,
+						remote_vars_pa, remote_vars);
+		reactivate = 1;
+
+	} else {
+		DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->version));
 
+		stamp_diff = xpc_compare_stamps(&part->remote_rp_stamp,
+							&remote_rp_stamp);
+		if (stamp_diff != 0) {
+			DBUG_ON(stamp_diff >= 0);
+
+			/*
+			 * Other side rebooted and the previous XPC did support
+			 * the disengage request, as does the new one.
+			 */
+
+			DBUG_ON(xpc_partition_engaged(1UL << partid));
+			DBUG_ON(xpc_partition_disengage_requested(1UL <<
+								partid));
+
+			xpc_update_partition_info(part, remote_rp_version,
+						&remote_rp_stamp, remote_rp_pa,
+						remote_vars_pa, remote_vars);
+			reactivate = 1;
+		}
+	}
+
+	if (!xpc_partition_disengaged(part)) {
+		/* still waiting on other side to disengage from us */
+		return;
+	}
+
+	if (reactivate) {
 		part->reactivate_nasid = nasid;
 		XPC_DEACTIVATE_PARTITION(part, xpcReactivating);
+
+	} else if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version) &&
+			xpc_partition_disengage_requested(1UL << partid)) {
+		XPC_DEACTIVATE_PARTITION(part, xpcOtherGoingDown);
 	}
 }
 
@@ -643,14 +802,17 @@ xpc_identify_act_IRQ_sender(void)
 	u64 nasid;			/* remote nasid */
 	int n_IRQs_detected = 0;
 	AMO_t *act_amos;
-	struct xpc_rsvd_page *rp = (struct xpc_rsvd_page *) xpc_rsvd_page;
 
 
-	act_amos = xpc_vars->act_amos;
+	act_amos = xpc_vars->amos_page + XPC_ACTIVATE_IRQ_AMOS;
 
 
 	/* scan through act AMO variable looking for non-zero entries */
-	for (word = 0; word < XP_NASID_MASK_WORDS; word++) {
+	for (word = 0; word < xp_nasid_mask_words; word++) {
+
+		if (xpc_exiting) {
+			break;
+		}
 
 		nasid_mask = xpc_IPI_receive(&act_amos[word]);
 		if (nasid_mask == 0) {
@@ -668,7 +830,7 @@ xpc_identify_act_IRQ_sender(void)
 		 * remote nasid in our reserved pages machine mask.
 		 * This is used in the event of module reload.
 		 */
-		rp->mach_nasids[word] |= nasid_mask;
+		xpc_mach_nasids[word] |= nasid_mask;
 
 
 		/* locate the nasid(s) which sent interrupts */
@@ -688,6 +850,55 @@ xpc_identify_act_IRQ_sender(void)
 
 
 /*
+ * See if the other side has responded to a partition disengage request
+ * from us.
+ */
+int
+xpc_partition_disengaged(struct xpc_partition *part)
+{
+	partid_t partid = XPC_PARTID(part);
+	int disengaged;
+
+
+	disengaged = (xpc_partition_engaged(1UL << partid) == 0);
+	if (part->disengage_request_timeout) {
+		if (!disengaged) {
+			if (jiffies < part->disengage_request_timeout) {
+				/* timelimit hasn't been reached yet */
+				return 0;
+			}
+
+			/*
+			 * Other side hasn't responded to our disengage
+			 * request in a timely fashion, so assume it's dead.
+			 */
+
+			xpc_clear_partition_engaged(1UL << partid);
+			disengaged = 1;
+		}
+		part->disengage_request_timeout = 0;
+
+		/* cancel the timer function, provided it's not us */
+		if (!in_interrupt()) {
+			del_singleshot_timer_sync(&part->
+						      disengage_request_timer);
+		}
+
+		DBUG_ON(part->act_state != XPC_P_DEACTIVATING &&
+					part->act_state != XPC_P_INACTIVE);
+		if (part->act_state != XPC_P_INACTIVE) {
+			xpc_wakeup_channel_mgr(part);
+		}
+
+		if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
+			xpc_cancel_partition_disengage_request(part);
+		}
+	}
+	return disengaged;
+}
+
+
+/*
  * Mark specified partition as active.
  */
 enum xpc_retval
@@ -721,7 +932,6 @@ xpc_deactivate_partition(const int line, struct xpc_partition *part,
 				enum xpc_retval reason)
 {
 	unsigned long irq_flags;
-	partid_t partid = XPC_PARTID(part);
 
 
 	spin_lock_irqsave(&part->act_lock, irq_flags);
@@ -749,17 +959,27 @@ xpc_deactivate_partition(const int line, struct xpc_partition *part,
 
 	spin_unlock_irqrestore(&part->act_lock, irq_flags);
 
-	XPC_DISALLOW_HB(partid, xpc_vars);
+	if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
+		xpc_request_partition_disengage(part);
+		xpc_IPI_send_disengage(part);
 
-	dev_dbg(xpc_part, "bringing partition %d down, reason = %d\n", partid,
-		reason);
+		/* set a timelimit on the disengage request */
+		part->disengage_request_timeout = jiffies +
+					(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",
+		XPC_PARTID(part), reason);
 
-	xpc_partition_down(part, reason);
+	xpc_partition_going_down(part, reason);
 }
 
 
 /*
- * Mark specified partition as active.
+ * Mark specified partition as inactive.
  */
 void
 xpc_mark_partition_inactive(struct xpc_partition *part)
@@ -792,9 +1012,10 @@ xpc_discovery(void)
 	void *remote_rp_base;
 	struct xpc_rsvd_page *remote_rp;
 	struct xpc_vars *remote_vars;
-	u64 remote_rsvd_page_pa;
+	u64 remote_rp_pa;
 	u64 remote_vars_pa;
 	int region;
+	int region_size;
 	int max_regions;
 	int nasid;
 	struct xpc_rsvd_page *rp;
@@ -804,7 +1025,8 @@ xpc_discovery(void)
 	enum xpc_retval ret;
 
 
-	remote_rp = xpc_kmalloc_cacheline_aligned(XPC_RSVD_PAGE_ALIGNED_SIZE,
+	remote_rp = xpc_kmalloc_cacheline_aligned(XPC_RP_HEADER_SIZE +
+						xp_nasid_mask_bytes,
 						GFP_KERNEL, &remote_rp_base);
 	if (remote_rp == NULL) {
 		return;
@@ -812,13 +1034,13 @@ xpc_discovery(void)
 	remote_vars = (struct xpc_vars *) remote_rp;
 
 
-	discovered_nasids = kmalloc(sizeof(u64) * XP_NASID_MASK_WORDS,
+	discovered_nasids = kmalloc(sizeof(u64) * xp_nasid_mask_words,
 							GFP_KERNEL);
 	if (discovered_nasids == NULL) {
 		kfree(remote_rp_base);
 		return;
 	}
-	memset(discovered_nasids, 0, sizeof(u64) * XP_NASID_MASK_WORDS);
+	memset(discovered_nasids, 0, sizeof(u64) * xp_nasid_mask_words);
 
 	rp = (struct xpc_rsvd_page *) xpc_rsvd_page;
 
@@ -827,11 +1049,19 @@ xpc_discovery(void)
 	 * nodes that can comprise an access protection grouping. The access
 	 * protection is in regards to memory, IOI and IPI.
 	 */
-//>>> move the next two #defines into either include/asm-ia64/sn/arch.h or
-//>>> include/asm-ia64/sn/addrs.h
-#define SH1_MAX_REGIONS		64
-#define SH2_MAX_REGIONS		256
-	max_regions = is_shub2() ? SH2_MAX_REGIONS : SH1_MAX_REGIONS;
+	max_regions = 64;
+	region_size = sn_region_size;
+
+	switch (region_size) {
+	case 128:
+		max_regions *= 2;
+	case 64:
+		max_regions *= 2;
+	case 32:
+		max_regions *= 2;
+		region_size = 16;
+		DBUG_ON(!is_shub2());
+	}
 
 	for (region = 0; region < max_regions; region++) {
 
@@ -841,8 +1071,8 @@ xpc_discovery(void)
 
 		dev_dbg(xpc_part, "searching region %d\n", region);
 
-		for (nasid = (region * sn_region_size * 2);
-		     nasid < ((region + 1) * sn_region_size * 2);
+		for (nasid = (region * region_size * 2);
+		     nasid < ((region + 1) * region_size * 2);
 		     nasid += 2) {
 
 			if ((volatile int) xpc_exiting) {
@@ -852,14 +1082,14 @@ xpc_discovery(void)
 			dev_dbg(xpc_part, "checking nasid %d\n", nasid);
 
 
-			if (XPC_NASID_IN_ARRAY(nasid, rp->part_nasids)) {
+			if (XPC_NASID_IN_ARRAY(nasid, xpc_part_nasids)) {
 				dev_dbg(xpc_part, "PROM indicates Nasid %d is "
 					"part of the local partition; skipping "
 					"region\n", nasid);
 				break;
 			}
 
-			if (!(XPC_NASID_IN_ARRAY(nasid, rp->mach_nasids))) {
+			if (!(XPC_NASID_IN_ARRAY(nasid, xpc_mach_nasids))) {
 				dev_dbg(xpc_part, "PROM indicates Nasid %d was "
 					"not on Numa-Link network at reset\n",
 					nasid);
@@ -877,7 +1107,7 @@ xpc_discovery(void)
 			/* pull over the reserved page structure */
 
 			ret = xpc_get_remote_rp(nasid, discovered_nasids,
-					      remote_rp, &remote_rsvd_page_pa);
+					      remote_rp, &remote_rp_pa);
 			if (ret != xpcSuccess) {
 				dev_dbg(xpc_part, "unable to get reserved page "
 					"from nasid %d, reason=%d\n", nasid,
@@ -948,6 +1178,13 @@ xpc_discovery(void)
 				remote_vars->act_nasid,
 				remote_vars->act_phys_cpuid);
 
+			if (XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->
+								version)) {
+				part->remote_amos_page_pa =
+						remote_vars->amos_page_pa;
+				xpc_mark_partition_disengaged(part);
+				xpc_cancel_partition_disengage_request(part);
+			}
 			xpc_IPI_send_activate(remote_vars);
 		}
 	}
@@ -974,12 +1211,12 @@ xpc_initiate_partid_to_nasids(partid_t partid, void *nasid_mask)
 		return xpcPartitionDown;
 	}
 
-	part_nasid_pa = part->remote_rp_pa +
-		(u64) &((struct xpc_rsvd_page *) 0)->part_nasids;
+	memset(nasid_mask, 0, XP_NASID_MASK_BYTES);
+
+	part_nasid_pa = (u64) XPC_RP_PART_NASIDS(part->remote_rp_pa);
 
 	bte_res = xp_bte_copy(part_nasid_pa, ia64_tpa((u64) nasid_mask),
-				L1_CACHE_ALIGN(XP_NASID_MASK_BYTES),
-				(BTE_NOTIFY | BTE_WACQUIRE), NULL);
+			xp_nasid_mask_bytes, (BTE_NOTIFY | BTE_WACQUIRE), NULL);
 
 	return xpc_map_bte_errors(bte_res);
 }