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linux/arch/ia64/sn/kernel/xpc_channel.c
Dean Nelson a460ef8d0a [IA64] fix possible XPC deadlock when disconnecting 
This patch eliminates a potential deadlock that is possible when XPC
disconnects a channel to a partition that has gone down. This deadlock will
occur if at least one of the kthreads created by XPC for the purpose of making
callouts to the channel's registerer is detained in the registerer and will
not be returning back to XPC until some registerer request occurs on the now
downed partition. The potential for a deadlock is removed by ensuring that
there always is a kthread available to make the channel disconnecting callout
to the registerer.

Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2006-12-12 11:48:53 -08:00

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/*
* 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) 2004-2006 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/mutex.h>
#include <linux/completion.h>
#include <asm/sn/bte.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/xpc.h>
/*
* Guarantee that the kzalloc'd memory is cacheline aligned.
*/
static void *
xpc_kzalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
{
/* see if kzalloc will give us cachline aligned memory by default */
*base = kzalloc(size, flags);
if (*base == NULL) {
return NULL;
}
if ((u64) *base == L1_CACHE_ALIGN((u64) *base)) {
return *base;
}
kfree(*base);
/* nope, we'll have to do it ourselves */
*base = kzalloc(size + L1_CACHE_BYTES, flags);
if (*base == NULL) {
return NULL;
}
return (void *) L1_CACHE_ALIGN((u64) *base);
}
/*
* 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);
mutex_init(&ch->msg_to_pull_mutex);
init_completion(&ch->wdisconnect_wait);
atomic_set(&ch->n_on_msg_allocate_wq, 0);
init_waitqueue_head(&ch->msg_allocate_wq);
init_waitqueue_head(&ch->idle_wq);
}
}
/*
* 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, cpuid;
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 = kzalloc(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;
}
part->nchannels = XPC_NCHANNELS;
/* allocate all the required GET/PUT values */
part->local_GPs = xpc_kzalloc_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;
}
part->remote_GPs = xpc_kzalloc_cacheline_aligned(XPC_GP_SIZE,
GFP_KERNEL, &part->remote_GPs_base);
if (part->remote_GPs == NULL) {
dev_err(xpc_chan, "can't get memory for remote get/put "
"values\n");
kfree(part->local_GPs_base);
part->local_GPs = NULL;
kfree(part->channels);
part->channels = NULL;
return xpcNoMemory;
}
/* allocate all the required open and close args */
part->local_openclose_args = xpc_kzalloc_cacheline_aligned(
XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
&part->local_openclose_args_base);
if (part->local_openclose_args == NULL) {
dev_err(xpc_chan, "can't get memory for local connect args\n");
kfree(part->remote_GPs_base);
part->remote_GPs = NULL;
kfree(part->local_GPs_base);
part->local_GPs = NULL;
kfree(part->channels);
part->channels = NULL;
return xpcNoMemory;
}
part->remote_openclose_args = xpc_kzalloc_cacheline_aligned(
XPC_OPENCLOSE_ARGS_SIZE, GFP_KERNEL,
&part->remote_openclose_args_base);
if (part->remote_openclose_args == NULL) {
dev_err(xpc_chan, "can't get memory for remote connect args\n");
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;
return xpcNoMemory;
}
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() */
/* 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, IRQF_SHARED,
part->IPI_owner, (void *) (u64) partid);
if (ret != 0) {
dev_err(xpc_chan, "can't register NOTIFY IRQ handler, "
"errno=%d\n", -ret);
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;
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.
*/
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);
cpuid = raw_smp_processor_id(); /* any CPU in this partition will do */
xpc_vars_part[partid].IPI_nasid = cpuid_to_nasid(cpuid);
xpc_vars_part[partid].IPI_phys_cpuid = cpu_physical_id(cpuid);
xpc_vars_part[partid].nchannels = part->nchannels;
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) 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 */
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_kzalloc_cacheline_aligned(nbytes,
GFP_KERNEL,
&ch->local_msgqueue_base);
if (ch->local_msgqueue == NULL) {
continue;
}
nbytes = nentries * sizeof(struct xpc_notify);
ch->notify_queue = kzalloc(nbytes, GFP_KERNEL);
if (ch->notify_queue == NULL) {
kfree(ch->local_msgqueue_base);
ch->local_msgqueue = NULL;
continue;
}
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_kzalloc_cacheline_aligned(nbytes,
GFP_KERNEL,
&ch->remote_msgqueue_base);
if (ch->remote_msgqueue == NULL) {
continue;
}
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;
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;
}
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, 0);
spin_lock_irqsave(&ch->lock, *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.
*
* 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;
}
}
/*
* 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 channel_was_connected = (ch->flags & XPC_C_WASCONNECTED);
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->kthreads_assigned) > 0 ||
atomic_read(&ch->references) > 0) {
return;
}
DBUG_ON((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
!(ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE));
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;
}
} else {
/* 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;
}
}
/* 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 */
if (ch->flags & XPC_C_DISCONNECTINGCALLOUT_MADE) {
spin_unlock_irqrestore(&ch->lock, *irq_flags);
xpc_disconnect_callout(ch, xpcDisconnected);
spin_lock_irqsave(&ch->lock, *irq_flags);
}
/* 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 (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) {
/* we won't lose the CPU since we're holding ch->lock */
complete(&ch->wdisconnect_wait);
} 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;
}
}
/*
* 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);
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) {
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 RCLOSEREQUEST 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);
DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
goto again;
}
if (ch->flags & XPC_C_DISCONNECTED) {
if (!(IPI_flags & XPC_IPI_OPENREQUEST)) {
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;
}
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);
DBUG_ON(IPI_flags & XPC_IPI_CLOSEREPLY);
spin_unlock_irqrestore(&ch->lock, irq_flags);
return;
}
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));
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;
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 (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;
}
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
*/
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;
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;
}
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);
/*
* 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 (mutex_trylock(&registration->mutex) == 0) {
return xpcRetry;
}
if (!XPC_CHANNEL_REGISTERED(ch->number)) {
mutex_unlock(&registration->mutex);
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);
mutex_unlock(&registration->mutex);
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.
*/
mutex_unlock(&registration->mutex);
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);
}
mutex_unlock(&registration->mutex);
/* 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;
}
/*
* 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);
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);
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_CONNECTEDCALLOUT_MADE) {
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;
u32 ch_flags;
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);
}
ch_flags = ch->flags; /* need an atomic snapshot of 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 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()
* at the same time. Nor will it ever make multiple calls to either function
* at the same time.
*/
void
xpc_partition_going_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 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);
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_engaged) != 0);
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];
/*
* 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)
{
/* 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);
}
}
/*
* 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);
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);
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_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.
*/
void
xpc_disconnect_channel(const int line, struct xpc_channel *ch,
enum xpc_retval reason, unsigned long *irq_flags)
{
u32 channel_was_connected = (ch->flags & XPC_C_CONNECTED);
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);
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);
xpc_IPI_send_closerequest(ch, irq_flags);
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_up_all(&ch->idle_wq);
} else if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
!(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
/* start a kthread that will do the xpcDisconnecting callout */
xpc_create_kthreads(ch, 1, 1);
}
/* 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);
}
spin_lock_irqsave(&ch->lock, *irq_flags);
}
void
xpc_disconnect_callout(struct xpc_channel *ch, enum xpc_retval reason)
{
/*
* 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.
*/
if (ch->func != NULL) {
dev_dbg(xpc_chan, "ch->func() called, reason=%d, partid=%d, "
"channel=%d\n", reason, ch->partid, ch->number);
ch->func(reason, ch->partid, ch->number, NULL, ch->key);
dev_dbg(xpc_chan, "ch->func() returned, reason=%d, partid=%d, "
"channel=%d\n", 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 = NULL;
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 = notify;
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;
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(&notify->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 (mutex_lock_interruptible(&ch->msg_to_pull_mutex) != 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);
mutex_unlock(&ch->msg_to_pull_mutex);
return NULL;
}
mb(); /* >>> this may not be needed, we're not sure */
ch->next_msg_to_pull += nmsgs;
}
mutex_unlock(&ch->msg_to_pull_mutex);
/* 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);
}
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