[IA64-SGI] SGI Altix cross partition functionality [2/3]
This patch contains the communication module (XPC) for cross partition
communication on a partitioned SGI Altix.
Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/sn/kernel/xpc_channel.c b/arch/ia64/sn/kernel/xpc_channel.c
new file mode 100644
index 0000000..0bf6fbc
--- /dev/null
+++ b/arch/ia64/sn/kernel/xpc_channel.c
@@ -0,0 +1,2297 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 2004-2005 Silicon Graphics, Inc. All Rights Reserved.
+ */
+
+
+/*
+ * Cross Partition Communication (XPC) channel support.
+ *
+ * This is the part of XPC that manages the channels and
+ * sends/receives messages across them to/from other partitions.
+ *
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/cache.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <asm/sn/bte.h>
+#include <asm/sn/sn_sal.h>
+#include "xpc.h"
+
+
+/*
+ * Set up the initial values for the XPartition Communication channels.
+ */
+static void
+xpc_initialize_channels(struct xpc_partition *part, partid_t partid)
+{
+ int ch_number;
+ struct xpc_channel *ch;
+
+
+ for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
+ ch = &part->channels[ch_number];
+
+ ch->partid = partid;
+ ch->number = ch_number;
+ ch->flags = XPC_C_DISCONNECTED;
+
+ ch->local_GP = &part->local_GPs[ch_number];
+ ch->local_openclose_args =
+ &part->local_openclose_args[ch_number];
+
+ atomic_set(&ch->kthreads_assigned, 0);
+ atomic_set(&ch->kthreads_idle, 0);
+ atomic_set(&ch->kthreads_active, 0);
+
+ atomic_set(&ch->references, 0);
+ atomic_set(&ch->n_to_notify, 0);
+
+ spin_lock_init(&ch->lock);
+ sema_init(&ch->msg_to_pull_sema, 1); /* mutex */
+
+ atomic_set(&ch->n_on_msg_allocate_wq, 0);
+ init_waitqueue_head(&ch->msg_allocate_wq);
+ init_waitqueue_head(&ch->idle_wq);
+ }
+}
+
+
+/*
+ * Setup the infrastructure necessary to support XPartition Communication
+ * between the specified remote partition and the local one.
+ */
+enum xpc_retval
+xpc_setup_infrastructure(struct xpc_partition *part)
+{
+ int ret;
+ struct timer_list *timer;
+ partid_t partid = XPC_PARTID(part);
+
+
+ /*
+ * Zero out MOST of the entry for this partition. Only the fields
+ * starting with `nchannels' will be zeroed. The preceding fields must
+ * remain `viable' across partition ups and downs, since they may be
+ * referenced during this memset() operation.
+ */
+ memset(&part->nchannels, 0, sizeof(struct xpc_partition) -
+ offsetof(struct xpc_partition, nchannels));
+
+ /*
+ * Allocate all of the channel structures as a contiguous chunk of
+ * memory.
+ */
+ part->channels = kmalloc(sizeof(struct xpc_channel) * XPC_NCHANNELS,
+ GFP_KERNEL);
+ if (part->channels == NULL) {
+ dev_err(xpc_chan, "can't get memory for channels\n");
+ return xpcNoMemory;
+ }
+ memset(part->channels, 0, sizeof(struct xpc_channel) * XPC_NCHANNELS);
+
+ part->nchannels = XPC_NCHANNELS;
+
+
+ /* allocate all the required GET/PUT values */
+
+ part->local_GPs = xpc_kmalloc_cacheline_aligned(XPC_GP_SIZE,
+ GFP_KERNEL, &part->local_GPs_base);
+ if (part->local_GPs == NULL) {
+ kfree(part->channels);
+ part->channels = NULL;
+ dev_err(xpc_chan, "can't get memory for local get/put "
+ "values\n");
+ return xpcNoMemory;
+ }
+ memset(part->local_GPs, 0, XPC_GP_SIZE);
+
+ part->remote_GPs = xpc_kmalloc_cacheline_aligned(XPC_GP_SIZE,
+ GFP_KERNEL, &part->remote_GPs_base);
+ if (part->remote_GPs == NULL) {
+ kfree(part->channels);
+ part->channels = NULL;
+ kfree(part->local_GPs_base);
+ part->local_GPs = NULL;
+ dev_err(xpc_chan, "can't get memory for remote get/put "
+ "values\n");
+ return xpcNoMemory;
+ }
+ memset(part->remote_GPs, 0, XPC_GP_SIZE);
+
+
+ /* allocate all the required open and close args */
+
+ part->local_openclose_args = xpc_kmalloc_cacheline_aligned(
+ XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
+ &part->local_openclose_args_base);
+ if (part->local_openclose_args == NULL) {
+ kfree(part->channels);
+ part->channels = NULL;
+ kfree(part->local_GPs_base);
+ part->local_GPs = NULL;
+ kfree(part->remote_GPs_base);
+ part->remote_GPs = NULL;
+ dev_err(xpc_chan, "can't get memory for local connect args\n");
+ return xpcNoMemory;
+ }
+ memset(part->local_openclose_args, 0, XPC_OPENCLOSE_ARGS_SIZE);
+
+ part->remote_openclose_args = xpc_kmalloc_cacheline_aligned(
+ XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
+ &part->remote_openclose_args_base);
+ if (part->remote_openclose_args == NULL) {
+ kfree(part->channels);
+ part->channels = NULL;
+ kfree(part->local_GPs_base);
+ part->local_GPs = NULL;
+ kfree(part->remote_GPs_base);
+ part->remote_GPs = NULL;
+ kfree(part->local_openclose_args_base);
+ part->local_openclose_args = NULL;
+ dev_err(xpc_chan, "can't get memory for remote connect args\n");
+ return xpcNoMemory;
+ }
+ memset(part->remote_openclose_args, 0, XPC_OPENCLOSE_ARGS_SIZE);
+
+
+ xpc_initialize_channels(part, partid);
+
+ atomic_set(&part->nchannels_active, 0);
+
+
+ /* local_IPI_amo were set to 0 by an earlier memset() */
+
+ /* Initialize this partitions AMO_t structure */
+ part->local_IPI_amo_va = xpc_IPI_init(partid);
+
+ spin_lock_init(&part->IPI_lock);
+
+ atomic_set(&part->channel_mgr_requests, 1);
+ init_waitqueue_head(&part->channel_mgr_wq);
+
+ sprintf(part->IPI_owner, "xpc%02d", partid);
+ ret = request_irq(SGI_XPC_NOTIFY, xpc_notify_IRQ_handler, SA_SHIRQ,
+ part->IPI_owner, (void *) (u64) partid);
+ if (ret != 0) {
+ kfree(part->channels);
+ part->channels = NULL;
+ kfree(part->local_GPs_base);
+ part->local_GPs = NULL;
+ kfree(part->remote_GPs_base);
+ part->remote_GPs = NULL;
+ kfree(part->local_openclose_args_base);
+ part->local_openclose_args = NULL;
+ kfree(part->remote_openclose_args_base);
+ part->remote_openclose_args = NULL;
+ dev_err(xpc_chan, "can't register NOTIFY IRQ handler, "
+ "errno=%d\n", -ret);
+ return xpcLackOfResources;
+ }
+
+ /* Setup a timer to check for dropped IPIs */
+ timer = &part->dropped_IPI_timer;
+ init_timer(timer);
+ timer->function = (void (*)(unsigned long)) xpc_dropped_IPI_check;
+ timer->data = (unsigned long) part;
+ timer->expires = jiffies + XPC_P_DROPPED_IPI_WAIT;
+ add_timer(timer);
+
+ /*
+ * With the setting of the partition setup_state to XPC_P_SETUP, we're
+ * declaring that this partition is ready to go.
+ */
+ (volatile u8) part->setup_state = XPC_P_SETUP;
+
+
+ /*
+ * Setup the per partition specific variables required by the
+ * remote partition to establish channel connections with us.
+ *
+ * The setting of the magic # indicates that these per partition
+ * specific variables are ready to be used.
+ */
+ xpc_vars_part[partid].GPs_pa = __pa(part->local_GPs);
+ xpc_vars_part[partid].openclose_args_pa =
+ __pa(part->local_openclose_args);
+ xpc_vars_part[partid].IPI_amo_pa = __pa(part->local_IPI_amo_va);
+ xpc_vars_part[partid].IPI_nasid = cpuid_to_nasid(smp_processor_id());
+ xpc_vars_part[partid].IPI_phys_cpuid =
+ cpu_physical_id(smp_processor_id());
+ xpc_vars_part[partid].nchannels = part->nchannels;
+ (volatile u64) xpc_vars_part[partid].magic = XPC_VP_MAGIC1;
+
+ return xpcSuccess;
+}
+
+
+/*
+ * Create a wrapper that hides the underlying mechanism for pulling a cacheline
+ * (or multiple cachelines) from a remote partition.
+ *
+ * src must be a cacheline aligned physical address on the remote partition.
+ * dst must be a cacheline aligned virtual address on this partition.
+ * cnt must be an cacheline sized
+ */
+static enum xpc_retval
+xpc_pull_remote_cachelines(struct xpc_partition *part, void *dst,
+ const void *src, size_t cnt)
+{
+ bte_result_t bte_ret;
+
+
+ DBUG_ON((u64) src != L1_CACHE_ALIGN((u64) src));
+ DBUG_ON((u64) dst != L1_CACHE_ALIGN((u64) dst));
+ DBUG_ON(cnt != L1_CACHE_ALIGN(cnt));
+
+ if (part->act_state == XPC_P_DEACTIVATING) {
+ return part->reason;
+ }
+
+ bte_ret = xp_bte_copy((u64) src, (u64) ia64_tpa((u64) dst),
+ (u64) cnt, (BTE_NORMAL | BTE_WACQUIRE), NULL);
+ if (bte_ret == BTE_SUCCESS) {
+ return xpcSuccess;
+ }
+
+ dev_dbg(xpc_chan, "xp_bte_copy() from partition %d failed, ret=%d\n",
+ XPC_PARTID(part), bte_ret);
+
+ return xpc_map_bte_errors(bte_ret);
+}
+
+
+/*
+ * Pull the remote per partititon specific variables from the specified
+ * partition.
+ */
+enum xpc_retval
+xpc_pull_remote_vars_part(struct xpc_partition *part)
+{
+ u8 buffer[L1_CACHE_BYTES * 2];
+ struct xpc_vars_part *pulled_entry_cacheline =
+ (struct xpc_vars_part *) L1_CACHE_ALIGN((u64) buffer);
+ struct xpc_vars_part *pulled_entry;
+ u64 remote_entry_cacheline_pa, remote_entry_pa;
+ partid_t partid = XPC_PARTID(part);
+ enum xpc_retval ret;
+
+
+ /* pull the cacheline that contains the variables we're interested in */
+
+ DBUG_ON(part->remote_vars_part_pa !=
+ L1_CACHE_ALIGN(part->remote_vars_part_pa));
+ DBUG_ON(sizeof(struct xpc_vars_part) != L1_CACHE_BYTES / 2);
+
+ remote_entry_pa = part->remote_vars_part_pa +
+ sn_partition_id * sizeof(struct xpc_vars_part);
+
+ remote_entry_cacheline_pa = (remote_entry_pa & ~(L1_CACHE_BYTES - 1));
+
+ pulled_entry = (struct xpc_vars_part *) ((u64) pulled_entry_cacheline +
+ (remote_entry_pa & (L1_CACHE_BYTES - 1)));
+
+ ret = xpc_pull_remote_cachelines(part, pulled_entry_cacheline,
+ (void *) remote_entry_cacheline_pa,
+ L1_CACHE_BYTES);
+ if (ret != xpcSuccess) {
+ dev_dbg(xpc_chan, "failed to pull XPC vars_part from "
+ "partition %d, ret=%d\n", partid, ret);
+ return ret;
+ }
+
+
+ /* see if they've been set up yet */
+
+ if (pulled_entry->magic != XPC_VP_MAGIC1 &&
+ pulled_entry->magic != XPC_VP_MAGIC2) {
+
+ if (pulled_entry->magic != 0) {
+ dev_dbg(xpc_chan, "partition %d's XPC vars_part for "
+ "partition %d has bad magic value (=0x%lx)\n",
+ partid, sn_partition_id, pulled_entry->magic);
+ return xpcBadMagic;
+ }
+
+ /* they've not been initialized yet */
+ return xpcRetry;
+ }
+
+ if (xpc_vars_part[partid].magic == XPC_VP_MAGIC1) {
+
+ /* validate the variables */
+
+ if (pulled_entry->GPs_pa == 0 ||
+ pulled_entry->openclose_args_pa == 0 ||
+ pulled_entry->IPI_amo_pa == 0) {
+
+ dev_err(xpc_chan, "partition %d's XPC vars_part for "
+ "partition %d are not valid\n", partid,
+ sn_partition_id);
+ return xpcInvalidAddress;
+ }
+
+ /* the variables we imported look to be valid */
+
+ part->remote_GPs_pa = pulled_entry->GPs_pa;
+ part->remote_openclose_args_pa =
+ pulled_entry->openclose_args_pa;
+ part->remote_IPI_amo_va =
+ (AMO_t *) __va(pulled_entry->IPI_amo_pa);
+ part->remote_IPI_nasid = pulled_entry->IPI_nasid;
+ part->remote_IPI_phys_cpuid = pulled_entry->IPI_phys_cpuid;
+
+ if (part->nchannels > pulled_entry->nchannels) {
+ part->nchannels = pulled_entry->nchannels;
+ }
+
+ /* let the other side know that we've pulled their variables */
+
+ (volatile u64) xpc_vars_part[partid].magic = XPC_VP_MAGIC2;
+ }
+
+ if (pulled_entry->magic == XPC_VP_MAGIC1) {
+ return xpcRetry;
+ }
+
+ return xpcSuccess;
+}
+
+
+/*
+ * Get the IPI flags and pull the openclose args and/or remote GPs as needed.
+ */
+static u64
+xpc_get_IPI_flags(struct xpc_partition *part)
+{
+ unsigned long irq_flags;
+ u64 IPI_amo;
+ enum xpc_retval ret;
+
+
+ /*
+ * See if there are any IPI flags to be handled.
+ */
+
+ spin_lock_irqsave(&part->IPI_lock, irq_flags);
+ if ((IPI_amo = part->local_IPI_amo) != 0) {
+ part->local_IPI_amo = 0;
+ }
+ spin_unlock_irqrestore(&part->IPI_lock, irq_flags);
+
+
+ if (XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(IPI_amo)) {
+ ret = xpc_pull_remote_cachelines(part,
+ part->remote_openclose_args,
+ (void *) part->remote_openclose_args_pa,
+ XPC_OPENCLOSE_ARGS_SIZE);
+ if (ret != xpcSuccess) {
+ XPC_DEACTIVATE_PARTITION(part, ret);
+
+ dev_dbg(xpc_chan, "failed to pull openclose args from "
+ "partition %d, ret=%d\n", XPC_PARTID(part),
+ ret);
+
+ /* don't bother processing IPIs anymore */
+ IPI_amo = 0;
+ }
+ }
+
+ if (XPC_ANY_MSG_IPI_FLAGS_SET(IPI_amo)) {
+ ret = xpc_pull_remote_cachelines(part, part->remote_GPs,
+ (void *) part->remote_GPs_pa,
+ XPC_GP_SIZE);
+ if (ret != xpcSuccess) {
+ XPC_DEACTIVATE_PARTITION(part, ret);
+
+ dev_dbg(xpc_chan, "failed to pull GPs from partition "
+ "%d, ret=%d\n", XPC_PARTID(part), ret);
+
+ /* don't bother processing IPIs anymore */
+ IPI_amo = 0;
+ }
+ }
+
+ return IPI_amo;
+}
+
+
+/*
+ * Allocate the local message queue and the notify queue.
+ */
+static enum xpc_retval
+xpc_allocate_local_msgqueue(struct xpc_channel *ch)
+{
+ unsigned long irq_flags;
+ int nentries;
+ size_t nbytes;
+
+
+ // >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
+ // >>> iterations of the for-loop, bail if set?
+
+ // >>> should we impose a minumum #of entries? like 4 or 8?
+ for (nentries = ch->local_nentries; nentries > 0; nentries--) {
+
+ nbytes = nentries * ch->msg_size;
+ ch->local_msgqueue = xpc_kmalloc_cacheline_aligned(nbytes,
+ (GFP_KERNEL | GFP_DMA),
+ &ch->local_msgqueue_base);
+ if (ch->local_msgqueue == NULL) {
+ continue;
+ }
+ memset(ch->local_msgqueue, 0, nbytes);
+
+ nbytes = nentries * sizeof(struct xpc_notify);
+ ch->notify_queue = kmalloc(nbytes, (GFP_KERNEL | GFP_DMA));
+ if (ch->notify_queue == NULL) {
+ kfree(ch->local_msgqueue_base);
+ ch->local_msgqueue = NULL;
+ continue;
+ }
+ memset(ch->notify_queue, 0, nbytes);
+
+ spin_lock_irqsave(&ch->lock, irq_flags);
+ if (nentries < ch->local_nentries) {
+ dev_dbg(xpc_chan, "nentries=%d local_nentries=%d, "
+ "partid=%d, channel=%d\n", nentries,
+ ch->local_nentries, ch->partid, ch->number);
+
+ ch->local_nentries = nentries;
+ }
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ return xpcSuccess;
+ }
+
+ dev_dbg(xpc_chan, "can't get memory for local message queue and notify "
+ "queue, partid=%d, channel=%d\n", ch->partid, ch->number);
+ return xpcNoMemory;
+}
+
+
+/*
+ * Allocate the cached remote message queue.
+ */
+static enum xpc_retval
+xpc_allocate_remote_msgqueue(struct xpc_channel *ch)
+{
+ unsigned long irq_flags;
+ int nentries;
+ size_t nbytes;
+
+
+ DBUG_ON(ch->remote_nentries <= 0);
+
+ // >>> may want to check for ch->flags & XPC_C_DISCONNECTING between
+ // >>> iterations of the for-loop, bail if set?
+
+ // >>> should we impose a minumum #of entries? like 4 or 8?
+ for (nentries = ch->remote_nentries; nentries > 0; nentries--) {
+
+ nbytes = nentries * ch->msg_size;
+ ch->remote_msgqueue = xpc_kmalloc_cacheline_aligned(nbytes,
+ (GFP_KERNEL | GFP_DMA),
+ &ch->remote_msgqueue_base);
+ if (ch->remote_msgqueue == NULL) {
+ continue;
+ }
+ memset(ch->remote_msgqueue, 0, nbytes);
+
+ spin_lock_irqsave(&ch->lock, irq_flags);
+ if (nentries < ch->remote_nentries) {
+ dev_dbg(xpc_chan, "nentries=%d remote_nentries=%d, "
+ "partid=%d, channel=%d\n", nentries,
+ ch->remote_nentries, ch->partid, ch->number);
+
+ ch->remote_nentries = nentries;
+ }
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ return xpcSuccess;
+ }
+
+ dev_dbg(xpc_chan, "can't get memory for cached remote message queue, "
+ "partid=%d, channel=%d\n", ch->partid, ch->number);
+ return xpcNoMemory;
+}
+
+
+/*
+ * Allocate message queues and other stuff associated with a channel.
+ *
+ * Note: Assumes all of the channel sizes are filled in.
+ */
+static enum xpc_retval
+xpc_allocate_msgqueues(struct xpc_channel *ch)
+{
+ unsigned long irq_flags;
+ int i;
+ enum xpc_retval ret;
+
+
+ DBUG_ON(ch->flags & XPC_C_SETUP);
+
+ if ((ret = xpc_allocate_local_msgqueue(ch)) != xpcSuccess) {
+ return ret;
+ }
+
+ if ((ret = xpc_allocate_remote_msgqueue(ch)) != xpcSuccess) {
+ kfree(ch->local_msgqueue_base);
+ ch->local_msgqueue = NULL;
+ kfree(ch->notify_queue);
+ ch->notify_queue = NULL;
+ return ret;
+ }
+
+ for (i = 0; i < ch->local_nentries; i++) {
+ /* use a semaphore as an event wait queue */
+ 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);
+
+ return xpcSuccess;
+}
+
+
+/*
+ * Process a connect message from a remote partition.
+ *
+ * Note: xpc_process_connect() is expecting to be called with the
+ * spin_lock_irqsave held and will leave it locked upon return.
+ */
+static void
+xpc_process_connect(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+ enum xpc_retval ret;
+
+
+ DBUG_ON(!spin_is_locked(&ch->lock));
+
+ if (!(ch->flags & XPC_C_OPENREQUEST) ||
+ !(ch->flags & XPC_C_ROPENREQUEST)) {
+ /* nothing more to do for now */
+ return;
+ }
+ DBUG_ON(!(ch->flags & XPC_C_CONNECTING));
+
+ if (!(ch->flags & XPC_C_SETUP)) {
+ spin_unlock_irqrestore(&ch->lock, *irq_flags);
+ ret = xpc_allocate_msgqueues(ch);
+ spin_lock_irqsave(&ch->lock, *irq_flags);
+
+ if (ret != xpcSuccess) {
+ XPC_DISCONNECT_CHANNEL(ch, ret, irq_flags);
+ }
+ if (ch->flags & (XPC_C_CONNECTED | XPC_C_DISCONNECTING)) {
+ return;
+ }
+
+ DBUG_ON(!(ch->flags & XPC_C_SETUP));
+ DBUG_ON(ch->local_msgqueue == NULL);
+ DBUG_ON(ch->remote_msgqueue == NULL);
+ }
+
+ if (!(ch->flags & XPC_C_OPENREPLY)) {
+ ch->flags |= XPC_C_OPENREPLY;
+ xpc_IPI_send_openreply(ch, irq_flags);
+ }
+
+ if (!(ch->flags & XPC_C_ROPENREPLY)) {
+ return;
+ }
+
+ DBUG_ON(ch->remote_msgqueue_pa == 0);
+
+ ch->flags = (XPC_C_CONNECTED | XPC_C_SETUP); /* clear all else */
+
+ dev_info(xpc_chan, "channel %d to partition %d connected\n",
+ ch->number, ch->partid);
+
+ spin_unlock_irqrestore(&ch->lock, *irq_flags);
+ xpc_create_kthreads(ch, 1);
+ spin_lock_irqsave(&ch->lock, *irq_flags);
+}
+
+
+/*
+ * Free up message queues and other stuff that were allocated for the specified
+ * channel.
+ *
+ * Note: ch->reason and ch->reason_line are left set for debugging purposes,
+ * they're cleared when XPC_C_DISCONNECTED is cleared.
+ */
+static void
+xpc_free_msgqueues(struct xpc_channel *ch)
+{
+ DBUG_ON(!spin_is_locked(&ch->lock));
+ DBUG_ON(atomic_read(&ch->n_to_notify) != 0);
+
+ ch->remote_msgqueue_pa = 0;
+ ch->func = NULL;
+ ch->key = NULL;
+ ch->msg_size = 0;
+ ch->local_nentries = 0;
+ ch->remote_nentries = 0;
+ ch->kthreads_assigned_limit = 0;
+ ch->kthreads_idle_limit = 0;
+
+ ch->local_GP->get = 0;
+ ch->local_GP->put = 0;
+ ch->remote_GP.get = 0;
+ ch->remote_GP.put = 0;
+ ch->w_local_GP.get = 0;
+ ch->w_local_GP.put = 0;
+ ch->w_remote_GP.get = 0;
+ ch->w_remote_GP.put = 0;
+ ch->next_msg_to_pull = 0;
+
+ if (ch->flags & XPC_C_SETUP) {
+ ch->flags &= ~XPC_C_SETUP;
+
+ dev_dbg(xpc_chan, "ch->flags=0x%x, partid=%d, channel=%d\n",
+ ch->flags, ch->partid, ch->number);
+
+ kfree(ch->local_msgqueue_base);
+ ch->local_msgqueue = NULL;
+ kfree(ch->remote_msgqueue_base);
+ 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);
+ }
+}
+
+
+/*
+ * spin_lock_irqsave() is expected to be held on entry.
+ */
+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;
+
+
+ DBUG_ON(!spin_is_locked(&ch->lock));
+
+ if (!(ch->flags & XPC_C_DISCONNECTING)) {
+ return;
+ }
+
+ DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
+
+ /* make sure all activity has settled down first */
+
+ if (atomic_read(&ch->references) > 0) {
+ return;
+ }
+ 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) {
+
+ /* as long as the other side is up do the full protocol */
+
+ if (!(ch->flags & XPC_C_RCLOSEREQUEST)) {
+ return;
+ }
+
+ if (!(ch->flags & XPC_C_CLOSEREPLY)) {
+ ch->flags |= XPC_C_CLOSEREPLY;
+ xpc_IPI_send_closereply(ch, irq_flags);
+ }
+
+ if (!(ch->flags & XPC_C_RCLOSEREPLY)) {
+ return;
+ }
+ }
+
+ /* both sides are disconnected now */
+
+ ch->flags = XPC_C_DISCONNECTED; /* clear all flags, but this one */
+
+ atomic_dec(&part->nchannels_active);
+
+ if (ch_flags & XPC_C_WASCONNECTED) {
+ dev_info(xpc_chan, "channel %d to partition %d disconnected, "
+ "reason=%d\n", ch->number, ch->partid, ch->reason);
+ }
+}
+
+
+/*
+ * Process a change in the channel's remote connection state.
+ */
+static void
+xpc_process_openclose_IPI(struct xpc_partition *part, int ch_number,
+ u8 IPI_flags)
+{
+ unsigned long irq_flags;
+ struct xpc_openclose_args *args =
+ &part->remote_openclose_args[ch_number];
+ struct xpc_channel *ch = &part->channels[ch_number];
+ enum xpc_retval reason;
+
+
+
+ spin_lock_irqsave(&ch->lock, irq_flags);
+
+
+ if (IPI_flags & XPC_IPI_CLOSEREQUEST) {
+
+ dev_dbg(xpc_chan, "XPC_IPI_CLOSEREQUEST (reason=%d) received "
+ "from partid=%d, channel=%d\n", args->reason,
+ ch->partid, 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.
+ */
+
+ if (ch->flags & XPC_C_RCLOSEREQUEST) {
+ DBUG_ON(!(ch->flags & XPC_C_DISCONNECTING));
+ DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
+ DBUG_ON(!(ch->flags & XPC_C_CLOSEREPLY));
+ DBUG_ON(ch->flags & XPC_C_RCLOSEREPLY);
+
+ DBUG_ON(!(IPI_flags & XPC_IPI_CLOSEREPLY));
+ IPI_flags &= ~XPC_IPI_CLOSEREPLY;
+ ch->flags |= XPC_C_RCLOSEREPLY;
+
+ /* both sides have finished disconnecting */
+ xpc_process_disconnect(ch, &irq_flags);
+ }
+
+ if (ch->flags & XPC_C_DISCONNECTED) {
+ // >>> explain this section
+
+ if (!(IPI_flags & XPC_IPI_OPENREQUEST)) {
+ DBUG_ON(part->act_state !=
+ XPC_P_DEACTIVATING);
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ return;
+ }
+
+ XPC_SET_REASON(ch, 0, 0);
+ ch->flags &= ~XPC_C_DISCONNECTED;
+
+ atomic_inc(&part->nchannels_active);
+ ch->flags |= (XPC_C_CONNECTING | XPC_C_ROPENREQUEST);
+ }
+
+ IPI_flags &= ~(XPC_IPI_OPENREQUEST | XPC_IPI_OPENREPLY);
+
+ /*
+ * The meaningful CLOSEREQUEST connection state fields are:
+ * reason = reason connection is to be closed
+ */
+
+ ch->flags |= XPC_C_RCLOSEREQUEST;
+
+ if (!(ch->flags & XPC_C_DISCONNECTING)) {
+ reason = args->reason;
+ if (reason <= xpcSuccess || reason > xpcUnknownReason) {
+ reason = xpcUnknownReason;
+ } else if (reason == xpcUnregistering) {
+ reason = xpcOtherUnregistering;
+ }
+
+ XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
+ } else {
+ xpc_process_disconnect(ch, &irq_flags);
+ }
+ }
+
+
+ if (IPI_flags & XPC_IPI_CLOSEREPLY) {
+
+ dev_dbg(xpc_chan, "XPC_IPI_CLOSEREPLY received from partid=%d,"
+ " channel=%d\n", ch->partid, ch->number);
+
+ if (ch->flags & XPC_C_DISCONNECTED) {
+ DBUG_ON(part->act_state != XPC_P_DEACTIVATING);
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ return;
+ }
+
+ DBUG_ON(!(ch->flags & XPC_C_CLOSEREQUEST));
+ DBUG_ON(!(ch->flags & XPC_C_RCLOSEREQUEST));
+
+ ch->flags |= XPC_C_RCLOSEREPLY;
+
+ if (ch->flags & XPC_C_CLOSEREPLY) {
+ /* both sides have finished disconnecting */
+ xpc_process_disconnect(ch, &irq_flags);
+ }
+ }
+
+
+ if (IPI_flags & XPC_IPI_OPENREQUEST) {
+
+ dev_dbg(xpc_chan, "XPC_IPI_OPENREQUEST (msg_size=%d, "
+ "local_nentries=%d) received from partid=%d, "
+ "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) {
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ return;
+ }
+ DBUG_ON(!(ch->flags & (XPC_C_DISCONNECTED |
+ XPC_C_OPENREQUEST)));
+ DBUG_ON(ch->flags & (XPC_C_ROPENREQUEST | XPC_C_ROPENREPLY |
+ XPC_C_OPENREPLY | XPC_C_CONNECTED));
+
+ /*
+ * The meaningful OPENREQUEST connection state fields are:
+ * 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);
+
+ ch->flags |= (XPC_C_ROPENREQUEST | XPC_C_CONNECTING);
+ ch->remote_nentries = args->local_nentries;
+
+
+ if (ch->flags & XPC_C_OPENREQUEST) {
+ if (args->msg_size != ch->msg_size) {
+ XPC_DISCONNECT_CHANNEL(ch, xpcUnequalMsgSizes,
+ &irq_flags);
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ return;
+ }
+ } else {
+ ch->msg_size = args->msg_size;
+
+ XPC_SET_REASON(ch, 0, 0);
+ ch->flags &= ~XPC_C_DISCONNECTED;
+
+ atomic_inc(&part->nchannels_active);
+ }
+
+ xpc_process_connect(ch, &irq_flags);
+ }
+
+
+ if (IPI_flags & XPC_IPI_OPENREPLY) {
+
+ dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY (local_msgqueue_pa=0x%lx, "
+ "local_nentries=%d, remote_nentries=%d) received from "
+ "partid=%d, channel=%d\n", args->local_msgqueue_pa,
+ args->local_nentries, args->remote_nentries,
+ ch->partid, ch->number);
+
+ if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ return;
+ }
+ DBUG_ON(!(ch->flags & XPC_C_OPENREQUEST));
+ DBUG_ON(!(ch->flags & XPC_C_ROPENREQUEST));
+ DBUG_ON(ch->flags & XPC_C_CONNECTED);
+
+ /*
+ * The meaningful OPENREPLY connection state fields are:
+ * local_msgqueue_pa = physical address of remote
+ * partition's local_msgqueue
+ * local_nentries = remote partition's local_nentries
+ * remote_nentries = remote partition's remote_nentries
+ */
+ DBUG_ON(args->local_msgqueue_pa == 0);
+ DBUG_ON(args->local_nentries == 0);
+ DBUG_ON(args->remote_nentries == 0);
+
+ ch->flags |= XPC_C_ROPENREPLY;
+ ch->remote_msgqueue_pa = args->local_msgqueue_pa;
+
+ if (args->local_nentries < ch->remote_nentries) {
+ dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY: new "
+ "remote_nentries=%d, old remote_nentries=%d, "
+ "partid=%d, channel=%d\n",
+ args->local_nentries, ch->remote_nentries,
+ ch->partid, ch->number);
+
+ ch->remote_nentries = args->local_nentries;
+ }
+ if (args->remote_nentries < ch->local_nentries) {
+ dev_dbg(xpc_chan, "XPC_IPI_OPENREPLY: new "
+ "local_nentries=%d, old local_nentries=%d, "
+ "partid=%d, channel=%d\n",
+ args->remote_nentries, ch->local_nentries,
+ ch->partid, ch->number);
+
+ ch->local_nentries = args->remote_nentries;
+ }
+
+ xpc_process_connect(ch, &irq_flags);
+ }
+
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+}
+
+
+/*
+ * Attempt to establish a channel connection to a remote partition.
+ */
+static enum xpc_retval
+xpc_connect_channel(struct xpc_channel *ch)
+{
+ unsigned long irq_flags;
+ struct xpc_registration *registration = &xpc_registrations[ch->number];
+
+
+ if (down_interruptible(®istration->sema) != 0) {
+ return xpcInterrupted;
+ }
+
+ if (!XPC_CHANNEL_REGISTERED(ch->number)) {
+ up(®istration->sema);
+ return xpcUnregistered;
+ }
+
+ spin_lock_irqsave(&ch->lock, irq_flags);
+
+ DBUG_ON(ch->flags & XPC_C_CONNECTED);
+ DBUG_ON(ch->flags & XPC_C_OPENREQUEST);
+
+ if (ch->flags & XPC_C_DISCONNECTING) {
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ up(®istration->sema);
+ return ch->reason;
+ }
+
+
+ /* add info from the channel connect registration to the channel */
+
+ ch->kthreads_assigned_limit = registration->assigned_limit;
+ ch->kthreads_idle_limit = registration->idle_limit;
+ DBUG_ON(atomic_read(&ch->kthreads_assigned) != 0);
+ DBUG_ON(atomic_read(&ch->kthreads_idle) != 0);
+ DBUG_ON(atomic_read(&ch->kthreads_active) != 0);
+
+ ch->func = registration->func;
+ DBUG_ON(registration->func == NULL);
+ ch->key = registration->key;
+
+ ch->local_nentries = registration->nentries;
+
+ if (ch->flags & XPC_C_ROPENREQUEST) {
+ if (registration->msg_size != ch->msg_size) {
+ /* the local and remote sides aren't the same */
+
+ /*
+ * Because XPC_DISCONNECT_CHANNEL() can block we're
+ * forced to up the registration sema before we unlock
+ * the channel lock. But that's okay here because we're
+ * done with the part that required the registration
+ * sema. XPC_DISCONNECT_CHANNEL() requires that the
+ * channel lock be locked and will unlock and relock
+ * the channel lock as needed.
+ */
+ up(®istration->sema);
+ XPC_DISCONNECT_CHANNEL(ch, xpcUnequalMsgSizes,
+ &irq_flags);
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ return xpcUnequalMsgSizes;
+ }
+ } else {
+ ch->msg_size = registration->msg_size;
+
+ XPC_SET_REASON(ch, 0, 0);
+ ch->flags &= ~XPC_C_DISCONNECTED;
+
+ atomic_inc(&xpc_partitions[ch->partid].nchannels_active);
+ }
+
+ up(®istration->sema);
+
+
+ /* initiate the connection */
+
+ ch->flags |= (XPC_C_OPENREQUEST | XPC_C_CONNECTING);
+ xpc_IPI_send_openrequest(ch, &irq_flags);
+
+ xpc_process_connect(ch, &irq_flags);
+
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+
+ return xpcSuccess;
+}
+
+
+/*
+ * 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(¬ify->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
+xpc_clear_local_msgqueue_flags(struct xpc_channel *ch)
+{
+ struct xpc_msg *msg;
+ s64 get;
+
+
+ get = ch->w_remote_GP.get;
+ do {
+ msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
+ (get % ch->local_nentries) * ch->msg_size);
+ msg->flags = 0;
+ } while (++get < (volatile s64) ch->remote_GP.get);
+}
+
+
+/*
+ * Clear some of the msg flags in the remote message queue.
+ */
+static inline void
+xpc_clear_remote_msgqueue_flags(struct xpc_channel *ch)
+{
+ struct xpc_msg *msg;
+ s64 put;
+
+
+ put = ch->w_remote_GP.put;
+ do {
+ msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
+ (put % ch->remote_nentries) * ch->msg_size);
+ msg->flags = 0;
+ } while (++put < (volatile s64) ch->remote_GP.put);
+}
+
+
+static void
+xpc_process_msg_IPI(struct xpc_partition *part, int ch_number)
+{
+ struct xpc_channel *ch = &part->channels[ch_number];
+ int nmsgs_sent;
+
+
+ ch->remote_GP = part->remote_GPs[ch_number];
+
+
+ /* See what, if anything, has changed for each connected channel */
+
+ xpc_msgqueue_ref(ch);
+
+ if (ch->w_remote_GP.get == ch->remote_GP.get &&
+ ch->w_remote_GP.put == ch->remote_GP.put) {
+ /* nothing changed since GPs were last pulled */
+ xpc_msgqueue_deref(ch);
+ return;
+ }
+
+ if (!(ch->flags & XPC_C_CONNECTED)){
+ xpc_msgqueue_deref(ch);
+ return;
+ }
+
+
+ /*
+ * First check to see if messages recently sent by us have been
+ * received by the other side. (The remote GET value will have
+ * changed since we last looked at it.)
+ */
+
+ if (ch->w_remote_GP.get != ch->remote_GP.get) {
+
+ /*
+ * We need to notify any senders that want to be notified
+ * that their sent messages have been received by their
+ * intended recipients. We need to do this before updating
+ * w_remote_GP.get so that we don't allocate the same message
+ * queue entries prematurely (see xpc_allocate_msg()).
+ */
+ if (atomic_read(&ch->n_to_notify) > 0) {
+ /*
+ * Notify senders that messages sent have been
+ * received and delivered by the other side.
+ */
+ xpc_notify_senders(ch, xpcMsgDelivered,
+ ch->remote_GP.get);
+ }
+
+ /*
+ * Clear msg->flags in previously sent messages, so that
+ * they're ready for xpc_allocate_msg().
+ */
+ xpc_clear_local_msgqueue_flags(ch);
+
+ (volatile s64) ch->w_remote_GP.get = ch->remote_GP.get;
+
+ dev_dbg(xpc_chan, "w_remote_GP.get changed to %ld, partid=%d, "
+ "channel=%d\n", ch->w_remote_GP.get, ch->partid,
+ ch->number);
+
+ /*
+ * If anyone was waiting for message queue entries to become
+ * available, wake them up.
+ */
+ if (atomic_read(&ch->n_on_msg_allocate_wq) > 0) {
+ wake_up(&ch->msg_allocate_wq);
+ }
+ }
+
+
+ /*
+ * Now check for newly sent messages by the other side. (The remote
+ * PUT value will have changed since we last looked at it.)
+ */
+
+ if (ch->w_remote_GP.put != ch->remote_GP.put) {
+ /*
+ * Clear msg->flags in previously received messages, so that
+ * they're ready for xpc_get_deliverable_msg().
+ */
+ xpc_clear_remote_msgqueue_flags(ch);
+
+ (volatile s64) ch->w_remote_GP.put = ch->remote_GP.put;
+
+ dev_dbg(xpc_chan, "w_remote_GP.put changed to %ld, partid=%d, "
+ "channel=%d\n", ch->w_remote_GP.put, ch->partid,
+ ch->number);
+
+ nmsgs_sent = ch->w_remote_GP.put - ch->w_local_GP.get;
+ if (nmsgs_sent > 0) {
+ dev_dbg(xpc_chan, "msgs waiting to be copied and "
+ "delivered=%d, partid=%d, channel=%d\n",
+ nmsgs_sent, ch->partid, ch->number);
+
+ if (ch->flags & XPC_C_CONNECTCALLOUT) {
+ xpc_activate_kthreads(ch, nmsgs_sent);
+ }
+ }
+ }
+
+ xpc_msgqueue_deref(ch);
+}
+
+
+void
+xpc_process_channel_activity(struct xpc_partition *part)
+{
+ unsigned long irq_flags;
+ u64 IPI_amo, IPI_flags;
+ struct xpc_channel *ch;
+ int ch_number;
+
+
+ IPI_amo = xpc_get_IPI_flags(part);
+
+ /*
+ * Initiate channel connections for registered channels.
+ *
+ * For each connected channel that has pending messages activate idle
+ * kthreads and/or create new kthreads as needed.
+ */
+
+ for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
+ ch = &part->channels[ch_number];
+
+
+ /*
+ * Process any open or close related IPI flags, and then deal
+ * with connecting or disconnecting the channel as required.
+ */
+
+ IPI_flags = XPC_GET_IPI_FLAGS(IPI_amo, ch_number);
+
+ if (XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(IPI_flags)) {
+ xpc_process_openclose_IPI(part, ch_number, IPI_flags);
+ }
+
+
+ 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);
+ continue;
+ }
+
+ if (part->act_state == XPC_P_DEACTIVATING) {
+ continue;
+ }
+
+ 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);
+ xpc_process_connect(ch, &irq_flags);
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ }
+ continue;
+ }
+
+
+ /*
+ * Process any message related IPI flags, this may involve the
+ * activation of kthreads to deliver any pending messages sent
+ * from the other partition.
+ */
+
+ if (XPC_ANY_MSG_IPI_FLAGS_SET(IPI_flags)) {
+ xpc_process_msg_IPI(part, ch_number);
+ }
+ }
+}
+
+
+/*
+ * XPC's heartbeat code calls this function to inform XPC that a partition has
+ * gone 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()
+ * at the same time. Nor will it ever make multiple calls to either function
+ * at the same time.
+ */
+void
+xpc_partition_down(struct xpc_partition *part, enum xpc_retval reason)
+{
+ unsigned long irq_flags;
+ int ch_number;
+ struct xpc_channel *ch;
+
+
+ dev_dbg(xpc_chan, "deactivating partition %d, reason=%d\n",
+ XPC_PARTID(part), reason);
+
+ if (!xpc_part_ref(part)) {
+ /* infrastructure for this partition isn't currently set up */
+ return;
+ }
+
+
+ /* disconnect all channels associated with the downed partition */
+
+ 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);
+
+ XPC_DISCONNECT_CHANNEL(ch, reason, &irq_flags);
+
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+ xpc_msgqueue_deref(ch);
+ }
+
+ xpc_wakeup_channel_mgr(part);
+
+ xpc_part_deref(part);
+}
+
+
+/*
+ * Teardown the infrastructure necessary to support XPartition Communication
+ * between the specified remote partition and the local one.
+ */
+void
+xpc_teardown_infrastructure(struct xpc_partition *part)
+{
+ partid_t partid = XPC_PARTID(part);
+
+
+ /*
+ * We start off by making this partition inaccessible to local
+ * processes by marking it as no longer setup. Then we make it
+ * inaccessible to remote processes by clearing the XPC per partition
+ * specific variable's magic # (which indicates that these variables
+ * are no longer valid) and by ignoring all XPC notify IPIs sent to
+ * this partition.
+ */
+
+ DBUG_ON(atomic_read(&part->nchannels_active) != 0);
+ DBUG_ON(part->setup_state != XPC_P_SETUP);
+ part->setup_state = XPC_P_WTEARDOWN;
+
+ xpc_vars_part[partid].magic = 0;
+
+
+ free_irq(SGI_XPC_NOTIFY, (void *) (u64) partid);
+
+
+ /*
+ * Before proceding with the teardown we have to wait until all
+ * existing references cease.
+ */
+ wait_event(part->teardown_wq, (atomic_read(&part->references) == 0));
+
+
+ /* now we can begin tearing down the infrastructure */
+
+ part->setup_state = XPC_P_TORNDOWN;
+
+ /* in case we've still got outstanding timers registered... */
+ del_timer_sync(&part->dropped_IPI_timer);
+
+ kfree(part->remote_openclose_args_base);
+ part->remote_openclose_args = NULL;
+ kfree(part->local_openclose_args_base);
+ part->local_openclose_args = NULL;
+ kfree(part->remote_GPs_base);
+ part->remote_GPs = NULL;
+ kfree(part->local_GPs_base);
+ part->local_GPs = NULL;
+ kfree(part->channels);
+ part->channels = NULL;
+ part->local_IPI_amo_va = NULL;
+}
+
+
+/*
+ * Called by XP at the time of channel connection registration to cause
+ * XPC to establish connections to all currently active partitions.
+ */
+void
+xpc_initiate_connect(int ch_number)
+{
+ partid_t partid;
+ struct xpc_partition *part;
+ struct xpc_channel *ch;
+
+
+ DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);
+
+ for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
+ part = &xpc_partitions[partid];
+
+ 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);
+ }
+
+ xpc_part_deref(part);
+ }
+ }
+}
+
+
+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) {
+ dev_dbg(xpc_chan, "ch->func() called, reason=xpcConnected, "
+ "partid=%d, channel=%d\n", ch->partid, ch->number);
+
+ ch->func(xpcConnected, ch->partid, ch->number,
+ (void *) (u64) ch->local_nentries, ch->key);
+
+ 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);
+}
+
+
+/*
+ * Called by XP at the time of channel connection unregistration to cause
+ * XPC to teardown all current connections for the specified channel.
+ *
+ * Before returning xpc_initiate_disconnect() will wait until all connections
+ * on the specified channel have been closed/torndown. So the caller can be
+ * assured that they will not be receiving any more callouts from XPC to the
+ * function they registered via xpc_connect().
+ *
+ * Arguments:
+ *
+ * ch_number - channel # to unregister.
+ */
+void
+xpc_initiate_disconnect(int ch_number)
+{
+ unsigned long irq_flags;
+ partid_t partid;
+ struct xpc_partition *part;
+ struct xpc_channel *ch;
+
+
+ DBUG_ON(ch_number < 0 || ch_number >= XPC_NCHANNELS);
+
+ /* initiate the channel disconnect for every active partition */
+ for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
+ part = &xpc_partitions[partid];
+
+ if (xpc_part_ref(part)) {
+ ch = &part->channels[ch_number];
+ xpc_msgqueue_ref(ch);
+
+ spin_lock_irqsave(&ch->lock, irq_flags);
+
+ XPC_DISCONNECT_CHANNEL(ch, xpcUnregistering,
+ &irq_flags);
+
+ spin_unlock_irqrestore(&ch->lock, irq_flags);
+
+ xpc_msgqueue_deref(ch);
+ xpc_part_deref(part);
+ }
+ }
+
+ xpc_disconnect_wait(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().
+ *
+ * THE CHANNEL IS TO BE LOCKED BY THE CALLER AND WILL REMAIN LOCKED UPON RETURN.
+ */
+void
+xpc_disconnect_channel(const int line, struct xpc_channel *ch,
+ enum xpc_retval reason, unsigned long *irq_flags)
+{
+ u32 flags;
+
+
+ DBUG_ON(!spin_is_locked(&ch->lock));
+
+ if (ch->flags & (XPC_C_DISCONNECTING | XPC_C_DISCONNECTED)) {
+ return;
+ }
+ DBUG_ON(!(ch->flags & (XPC_C_CONNECTING | XPC_C_CONNECTED)));
+
+ dev_dbg(xpc_chan, "reason=%d, line=%d, partid=%d, channel=%d\n",
+ reason, line, ch->partid, ch->number);
+
+ XPC_SET_REASON(ch, reason, line);
+
+ flags = ch->flags;
+ /* 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) {
+ ch->flags |= XPC_C_WASCONNECTED;
+ }
+
+ 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)
+{
+ /*
+ * Let the channel's registerer know that the channel is now
+ * 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.
+ */
+
+ if (ch->func != NULL) {
+ dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
+ "channel=%d\n", ch->reason, ch->partid, ch->number);
+
+ ch->func(ch->reason, 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);
+ }
+}
+
+
+/*
+ * Wait for a message entry to become available for the specified channel,
+ * but don't wait any longer than 1 jiffy.
+ */
+static enum xpc_retval
+xpc_allocate_msg_wait(struct xpc_channel *ch)
+{
+ enum xpc_retval ret;
+
+
+ if (ch->flags & XPC_C_DISCONNECTING) {
+ DBUG_ON(ch->reason == xpcInterrupted); // >>> Is this true?
+ return ch->reason;
+ }
+
+ atomic_inc(&ch->n_on_msg_allocate_wq);
+ ret = interruptible_sleep_on_timeout(&ch->msg_allocate_wq, 1);
+ atomic_dec(&ch->n_on_msg_allocate_wq);
+
+ if (ch->flags & XPC_C_DISCONNECTING) {
+ ret = ch->reason;
+ DBUG_ON(ch->reason == xpcInterrupted); // >>> Is this true?
+ } else if (ret == 0) {
+ ret = xpcTimeout;
+ } else {
+ ret = xpcInterrupted;
+ }
+
+ return ret;
+}
+
+
+/*
+ * Allocate an entry for a message from the message queue associated with the
+ * specified channel.
+ */
+static enum xpc_retval
+xpc_allocate_msg(struct xpc_channel *ch, u32 flags,
+ struct xpc_msg **address_of_msg)
+{
+ struct xpc_msg *msg;
+ enum xpc_retval ret;
+ s64 put;
+
+
+ /* this reference will be dropped in xpc_send_msg() */
+ xpc_msgqueue_ref(ch);
+
+ if (ch->flags & XPC_C_DISCONNECTING) {
+ xpc_msgqueue_deref(ch);
+ return ch->reason;
+ }
+ if (!(ch->flags & XPC_C_CONNECTED)) {
+ xpc_msgqueue_deref(ch);
+ return xpcNotConnected;
+ }
+
+
+ /*
+ * Get the next available message entry from the local message queue.
+ * If none are available, we'll make sure that we grab the latest
+ * GP values.
+ */
+ ret = xpcTimeout;
+
+ while (1) {
+
+ put = (volatile s64) ch->w_local_GP.put;
+ if (put - (volatile s64) ch->w_remote_GP.get <
+ ch->local_nentries) {
+
+ /* There are available message entries. We need to try
+ * to secure one for ourselves. We'll do this by trying
+ * to increment w_local_GP.put as long as someone else
+ * doesn't beat us to it. If they do, we'll have to
+ * try again.
+ */
+ if (cmpxchg(&ch->w_local_GP.put, put, put + 1) ==
+ put) {
+ /* we got the entry referenced by put */
+ break;
+ }
+ continue; /* try again */
+ }
+
+
+ /*
+ * There aren't any available msg entries at this time.
+ *
+ * In waiting for a message entry to become available,
+ * we set a timeout in case the other side is not
+ * sending completion IPIs. This lets us fake an IPI
+ * that will cause the IPI handler to fetch the latest
+ * GP values as if an IPI was sent by the other side.
+ */
+ if (ret == xpcTimeout) {
+ xpc_IPI_send_local_msgrequest(ch);
+ }
+
+ if (flags & XPC_NOWAIT) {
+ xpc_msgqueue_deref(ch);
+ return xpcNoWait;
+ }
+
+ ret = xpc_allocate_msg_wait(ch);
+ if (ret != xpcInterrupted && ret != xpcTimeout) {
+ xpc_msgqueue_deref(ch);
+ return ret;
+ }
+ }
+
+
+ /* get the message's address and initialize it */
+ msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
+ (put % ch->local_nentries) * ch->msg_size);
+
+
+ DBUG_ON(msg->flags != 0);
+ msg->number = put;
+
+ dev_dbg(xpc_chan, "w_local_GP.put changed to %ld; msg=0x%p, "
+ "msg_number=%ld, partid=%d, channel=%d\n", put + 1,
+ (void *) msg, msg->number, ch->partid, ch->number);
+
+ *address_of_msg = msg;
+
+ return xpcSuccess;
+}
+
+
+/*
+ * Allocate an entry for a message from the message queue associated with the
+ * specified channel. NOTE that this routine can sleep waiting for a message
+ * entry to become available. To not sleep, pass in the XPC_NOWAIT flag.
+ *
+ * Arguments:
+ *
+ * partid - ID of partition to which the channel is connected.
+ * ch_number - channel #.
+ * flags - see xpc.h for valid flags.
+ * payload - address of the allocated payload area pointer (filled in on
+ * return) in which the user-defined message is constructed.
+ */
+enum xpc_retval
+xpc_initiate_allocate(partid_t partid, int ch_number, u32 flags, void **payload)
+{
+ struct xpc_partition *part = &xpc_partitions[partid];
+ enum xpc_retval ret = xpcUnknownReason;
+ struct xpc_msg *msg;
+
+
+ DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
+ DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
+
+ *payload = NULL;
+
+ if (xpc_part_ref(part)) {
+ ret = xpc_allocate_msg(&part->channels[ch_number], flags, &msg);
+ xpc_part_deref(part);
+
+ if (msg != NULL) {
+ *payload = &msg->payload;
+ }
+ }
+
+ return ret;
+}
+
+
+/*
+ * Now we actually send the messages that are ready to be sent by advancing
+ * the local message queue's Put value and then send an IPI to the recipient
+ * partition.
+ */
+static void
+xpc_send_msgs(struct xpc_channel *ch, s64 initial_put)
+{
+ struct xpc_msg *msg;
+ s64 put = initial_put + 1;
+ int send_IPI = 0;
+
+
+ while (1) {
+
+ while (1) {
+ if (put == (volatile s64) ch->w_local_GP.put) {
+ break;
+ }
+
+ msg = (struct xpc_msg *) ((u64) ch->local_msgqueue +
+ (put % ch->local_nentries) * ch->msg_size);
+
+ if (!(msg->flags & XPC_M_READY)) {
+ break;
+ }
+
+ put++;
+ }
+
+ if (put == initial_put) {
+ /* nothing's changed */
+ break;
+ }
+
+ if (cmpxchg_rel(&ch->local_GP->put, initial_put, put) !=
+ initial_put) {
+ /* someone else beat us to it */
+ DBUG_ON((volatile s64) ch->local_GP->put < initial_put);
+ break;
+ }
+
+ /* we just set the new value of local_GP->put */
+
+ dev_dbg(xpc_chan, "local_GP->put changed to %ld, partid=%d, "
+ "channel=%d\n", put, ch->partid, ch->number);
+
+ send_IPI = 1;
+
+ /*
+ * We need to ensure that the message referenced by
+ * local_GP->put is not XPC_M_READY or that local_GP->put
+ * equals w_local_GP.put, so we'll go have a look.
+ */
+ initial_put = put;
+ }
+
+ if (send_IPI) {
+ xpc_IPI_send_msgrequest(ch);
+ }
+}
+
+
+/*
+ * Common code that does the actual sending of the message by advancing the
+ * local message queue's Put value and sends an IPI to the partition the
+ * message is being sent to.
+ */
+static enum xpc_retval
+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!!
+ s64 put, msg_number = msg->number;
+
+
+ DBUG_ON(notify_type == XPC_N_CALL && func == NULL);
+ DBUG_ON((((u64) msg - (u64) ch->local_msgqueue) / ch->msg_size) !=
+ msg_number % ch->local_nentries);
+ DBUG_ON(msg->flags & XPC_M_READY);
+
+ if (ch->flags & XPC_C_DISCONNECTING) {
+ /* drop the reference grabbed in xpc_allocate_msg() */
+ xpc_msgqueue_deref(ch);
+ return ch->reason;
+ }
+
+ if (notify_type != 0) {
+ /*
+ * Tell the remote side to send an ACK interrupt when the
+ * message has been delivered.
+ */
+ msg->flags |= XPC_M_INTERRUPT;
+
+ atomic_inc(&ch->n_to_notify);
+
+ notify = &ch->notify_queue[msg_number % ch->local_nentries];
+ notify->func = func;
+ notify->key = key;
+ (volatile u8) notify->type = notify_type;
+
+ // >>> is a mb() needed here?
+
+ if (ch->flags & XPC_C_DISCONNECTING) {
+ /*
+ * An error occurred between our last error check and
+ * this one. We will try to clear the type field from
+ * the notify entry. If we succeed then
+ * xpc_disconnect_channel() didn't already process
+ * the notify entry.
+ */
+ if (cmpxchg(¬ify->type, notify_type, 0) ==
+ notify_type) {
+ atomic_dec(&ch->n_to_notify);
+ ret = ch->reason;
+ }
+
+ /* drop the reference grabbed in xpc_allocate_msg() */
+ xpc_msgqueue_deref(ch);
+ return ret;
+ }
+ }
+
+ msg->flags |= XPC_M_READY;
+
+ /*
+ * The preceding store of msg->flags must occur before the following
+ * load of ch->local_GP->put.
+ */
+ mb();
+
+ /* see if the message is next in line to be sent, if so send it */
+
+ put = ch->local_GP->put;
+ if (put == msg_number) {
+ xpc_send_msgs(ch, put);
+ }
+
+ /* drop the reference grabbed in xpc_allocate_msg() */
+ xpc_msgqueue_deref(ch);
+ return ret;
+}
+
+
+/*
+ * Send a message previously allocated using xpc_initiate_allocate() on the
+ * specified channel connected to the specified partition.
+ *
+ * This routine will not wait for the message to be received, nor will
+ * notification be given when it does happen. Once this routine has returned
+ * the message entry allocated via xpc_initiate_allocate() is no longer
+ * accessable to the caller.
+ *
+ * This routine, although called by users, does not call xpc_part_ref() to
+ * ensure that the partition infrastructure is in place. It relies on the
+ * fact that we called xpc_msgqueue_ref() in xpc_allocate_msg().
+ *
+ * Arguments:
+ *
+ * partid - ID of partition to which the channel is connected.
+ * ch_number - channel # to send message on.
+ * payload - pointer to the payload area allocated via
+ * xpc_initiate_allocate().
+ */
+enum xpc_retval
+xpc_initiate_send(partid_t partid, int ch_number, void *payload)
+{
+ struct xpc_partition *part = &xpc_partitions[partid];
+ struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
+ enum xpc_retval ret;
+
+
+ dev_dbg(xpc_chan, "msg=0x%p, partid=%d, channel=%d\n", (void *) msg,
+ partid, ch_number);
+
+ DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
+ DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
+ DBUG_ON(msg == NULL);
+
+ ret = xpc_send_msg(&part->channels[ch_number], msg, 0, NULL, NULL);
+
+ return ret;
+}
+
+
+/*
+ * Send a message previously allocated using xpc_initiate_allocate on the
+ * specified channel connected to the specified partition.
+ *
+ * This routine will not wait for the message to be sent. Once this routine
+ * has returned the message entry allocated via xpc_initiate_allocate() is no
+ * longer accessable to the caller.
+ *
+ * Once the remote end of the channel has received the message, the function
+ * passed as an argument to xpc_initiate_send_notify() will be called. This
+ * allows the sender to free up or re-use any buffers referenced by the
+ * message, but does NOT mean the message has been processed at the remote
+ * end by a receiver.
+ *
+ * If this routine returns an error, the caller's function will NOT be called.
+ *
+ * This routine, although called by users, does not call xpc_part_ref() to
+ * ensure that the partition infrastructure is in place. It relies on the
+ * fact that we called xpc_msgqueue_ref() in xpc_allocate_msg().
+ *
+ * Arguments:
+ *
+ * partid - ID of partition to which the channel is connected.
+ * ch_number - channel # to send message on.
+ * payload - pointer to the payload area allocated via
+ * xpc_initiate_allocate().
+ * func - function to call with asynchronous notification of message
+ * receipt. THIS FUNCTION MUST BE NON-BLOCKING.
+ * key - user-defined key to be passed to the function when it's called.
+ */
+enum xpc_retval
+xpc_initiate_send_notify(partid_t partid, int ch_number, void *payload,
+ xpc_notify_func func, void *key)
+{
+ struct xpc_partition *part = &xpc_partitions[partid];
+ struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
+ enum xpc_retval ret;
+
+
+ dev_dbg(xpc_chan, "msg=0x%p, partid=%d, channel=%d\n", (void *) msg,
+ partid, ch_number);
+
+ DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
+ DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
+ DBUG_ON(msg == NULL);
+ DBUG_ON(func == NULL);
+
+ ret = xpc_send_msg(&part->channels[ch_number], msg, XPC_N_CALL,
+ func, key);
+ return ret;
+}
+
+
+static struct xpc_msg *
+xpc_pull_remote_msg(struct xpc_channel *ch, s64 get)
+{
+ struct xpc_partition *part = &xpc_partitions[ch->partid];
+ struct xpc_msg *remote_msg, *msg;
+ u32 msg_index, nmsgs;
+ u64 msg_offset;
+ enum xpc_retval ret;
+
+
+ if (down_interruptible(&ch->msg_to_pull_sema) != 0) {
+ /* we were interrupted by a signal */
+ return NULL;
+ }
+
+ while (get >= ch->next_msg_to_pull) {
+
+ /* pull as many messages as are ready and able to be pulled */
+
+ msg_index = ch->next_msg_to_pull % ch->remote_nentries;
+
+ DBUG_ON(ch->next_msg_to_pull >=
+ (volatile s64) ch->w_remote_GP.put);
+ nmsgs = (volatile s64) ch->w_remote_GP.put -
+ ch->next_msg_to_pull;
+ if (msg_index + nmsgs > ch->remote_nentries) {
+ /* ignore the ones that wrap the msg queue for now */
+ nmsgs = ch->remote_nentries - msg_index;
+ }
+
+ msg_offset = msg_index * ch->msg_size;
+ msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
+ msg_offset);
+ remote_msg = (struct xpc_msg *) (ch->remote_msgqueue_pa +
+ msg_offset);
+
+ if ((ret = xpc_pull_remote_cachelines(part, msg, remote_msg,
+ nmsgs * ch->msg_size)) != xpcSuccess) {
+
+ dev_dbg(xpc_chan, "failed to pull %d msgs starting with"
+ " msg %ld from partition %d, channel=%d, "
+ "ret=%d\n", nmsgs, ch->next_msg_to_pull,
+ ch->partid, ch->number, ret);
+
+ XPC_DEACTIVATE_PARTITION(part, ret);
+
+ up(&ch->msg_to_pull_sema);
+ return NULL;
+ }
+
+ mb(); /* >>> this may not be needed, we're not sure */
+
+ ch->next_msg_to_pull += nmsgs;
+ }
+
+ up(&ch->msg_to_pull_sema);
+
+ /* return the message we were looking for */
+ msg_offset = (get % ch->remote_nentries) * ch->msg_size;
+ msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue + msg_offset);
+
+ return msg;
+}
+
+
+/*
+ * Get a message to be delivered.
+ */
+static struct xpc_msg *
+xpc_get_deliverable_msg(struct xpc_channel *ch)
+{
+ struct xpc_msg *msg = NULL;
+ s64 get;
+
+
+ do {
+ if ((volatile u32) ch->flags & XPC_C_DISCONNECTING) {
+ break;
+ }
+
+ get = (volatile s64) ch->w_local_GP.get;
+ if (get == (volatile s64) ch->w_remote_GP.put) {
+ break;
+ }
+
+ /* There are messages waiting to be pulled and delivered.
+ * We need to try to secure one for ourselves. We'll do this
+ * by trying to increment w_local_GP.get and hope that no one
+ * else beats us to it. If they do, we'll we'll simply have
+ * to try again for the next one.
+ */
+
+ if (cmpxchg(&ch->w_local_GP.get, get, get + 1) == get) {
+ /* we got the entry referenced by get */
+
+ dev_dbg(xpc_chan, "w_local_GP.get changed to %ld, "
+ "partid=%d, channel=%d\n", get + 1,
+ ch->partid, ch->number);
+
+ /* pull the message from the remote partition */
+
+ msg = xpc_pull_remote_msg(ch, get);
+
+ DBUG_ON(msg != NULL && msg->number != get);
+ DBUG_ON(msg != NULL && (msg->flags & XPC_M_DONE));
+ DBUG_ON(msg != NULL && !(msg->flags & XPC_M_READY));
+
+ break;
+ }
+
+ } while (1);
+
+ return msg;
+}
+
+
+/*
+ * Deliver a message to its intended recipient.
+ */
+void
+xpc_deliver_msg(struct xpc_channel *ch)
+{
+ struct xpc_msg *msg;
+
+
+ if ((msg = xpc_get_deliverable_msg(ch)) != NULL) {
+
+ /*
+ * This ref is taken to protect the payload itself from being
+ * freed before the user is finished with it, which the user
+ * indicates by calling xpc_initiate_received().
+ */
+ xpc_msgqueue_ref(ch);
+
+ atomic_inc(&ch->kthreads_active);
+
+ if (ch->func != NULL) {
+ dev_dbg(xpc_chan, "ch->func() called, msg=0x%p, "
+ "msg_number=%ld, partid=%d, channel=%d\n",
+ (void *) msg, msg->number, ch->partid,
+ ch->number);
+
+ /* deliver the message to its intended recipient */
+ ch->func(xpcMsgReceived, ch->partid, ch->number,
+ &msg->payload, ch->key);
+
+ dev_dbg(xpc_chan, "ch->func() returned, msg=0x%p, "
+ "msg_number=%ld, partid=%d, channel=%d\n",
+ (void *) msg, msg->number, ch->partid,
+ ch->number);
+ }
+
+ atomic_dec(&ch->kthreads_active);
+ }
+}
+
+
+/*
+ * Now we actually acknowledge the messages that have been delivered and ack'd
+ * by advancing the cached remote message queue's Get value and if requested
+ * send an IPI to the message sender's partition.
+ */
+static void
+xpc_acknowledge_msgs(struct xpc_channel *ch, s64 initial_get, u8 msg_flags)
+{
+ struct xpc_msg *msg;
+ s64 get = initial_get + 1;
+ int send_IPI = 0;
+
+
+ while (1) {
+
+ while (1) {
+ if (get == (volatile s64) ch->w_local_GP.get) {
+ break;
+ }
+
+ msg = (struct xpc_msg *) ((u64) ch->remote_msgqueue +
+ (get % ch->remote_nentries) * ch->msg_size);
+
+ if (!(msg->flags & XPC_M_DONE)) {
+ break;
+ }
+
+ msg_flags |= msg->flags;
+ get++;
+ }
+
+ if (get == initial_get) {
+ /* nothing's changed */
+ break;
+ }
+
+ if (cmpxchg_rel(&ch->local_GP->get, initial_get, get) !=
+ initial_get) {
+ /* someone else beat us to it */
+ DBUG_ON((volatile s64) ch->local_GP->get <=
+ initial_get);
+ break;
+ }
+
+ /* we just set the new value of local_GP->get */
+
+ dev_dbg(xpc_chan, "local_GP->get changed to %ld, partid=%d, "
+ "channel=%d\n", get, ch->partid, ch->number);
+
+ send_IPI = (msg_flags & XPC_M_INTERRUPT);
+
+ /*
+ * We need to ensure that the message referenced by
+ * local_GP->get is not XPC_M_DONE or that local_GP->get
+ * equals w_local_GP.get, so we'll go have a look.
+ */
+ initial_get = get;
+ }
+
+ if (send_IPI) {
+ xpc_IPI_send_msgrequest(ch);
+ }
+}
+
+
+/*
+ * Acknowledge receipt of a delivered message.
+ *
+ * If a message has XPC_M_INTERRUPT set, send an interrupt to the partition
+ * that sent the message.
+ *
+ * This function, although called by users, does not call xpc_part_ref() to
+ * ensure that the partition infrastructure is in place. It relies on the
+ * fact that we called xpc_msgqueue_ref() in xpc_deliver_msg().
+ *
+ * Arguments:
+ *
+ * partid - ID of partition to which the channel is connected.
+ * ch_number - channel # message received on.
+ * payload - pointer to the payload area allocated via
+ * xpc_initiate_allocate().
+ */
+void
+xpc_initiate_received(partid_t partid, int ch_number, void *payload)
+{
+ struct xpc_partition *part = &xpc_partitions[partid];
+ struct xpc_channel *ch;
+ struct xpc_msg *msg = XPC_MSG_ADDRESS(payload);
+ s64 get, msg_number = msg->number;
+
+
+ DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
+ DBUG_ON(ch_number < 0 || ch_number >= part->nchannels);
+
+ ch = &part->channels[ch_number];
+
+ dev_dbg(xpc_chan, "msg=0x%p, msg_number=%ld, partid=%d, channel=%d\n",
+ (void *) msg, msg_number, ch->partid, ch->number);
+
+ DBUG_ON((((u64) msg - (u64) ch->remote_msgqueue) / ch->msg_size) !=
+ msg_number % ch->remote_nentries);
+ DBUG_ON(msg->flags & XPC_M_DONE);
+
+ msg->flags |= XPC_M_DONE;
+
+ /*
+ * The preceding store of msg->flags must occur before the following
+ * load of ch->local_GP->get.
+ */
+ mb();
+
+ /*
+ * See if this message is next in line to be acknowledged as having
+ * been delivered.
+ */
+ get = ch->local_GP->get;
+ if (get == msg_number) {
+ xpc_acknowledge_msgs(ch, get, msg->flags);
+ }
+
+ /* the call to xpc_msgqueue_ref() was done by xpc_deliver_msg() */
+ xpc_msgqueue_deref(ch);
+}
+