blob: 68355ef6f84170096b52aee5938a390143841e10 [file] [log] [blame]
/*
* 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) support - standard version.
*
* XPC provides a message passing capability that crosses partition
* boundaries. This module is made up of two parts:
*
* partition This part detects the presence/absence of other
* partitions. It provides a heartbeat and monitors
* the heartbeats of other partitions.
*
* channel This part manages the channels and sends/receives
* messages across them to/from other partitions.
*
* There are a couple of additional functions residing in XP, which
* provide an interface to XPC for its users.
*
*
* Caveats:
*
* . We currently have no way to determine which nasid an IPI came
* from. Thus, xpc_IPI_send() does a remote AMO write followed by
* an IPI. The AMO indicates where data is to be pulled from, so
* after the IPI arrives, the remote partition checks the AMO word.
* The IPI can actually arrive before the AMO however, so other code
* must periodically check for this case. Also, remote AMO operations
* do not reliably time out. Thus we do a remote PIO read solely to
* know whether the remote partition is down and whether we should
* stop sending IPIs to it. This remote PIO read operation is set up
* in a special nofault region so SAL knows to ignore (and cleanup)
* any errors due to the remote AMO write, PIO read, and/or PIO
* write operations.
*
* If/when new hardware solves this IPI problem, we should abandon
* the current approach.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
#include <linux/cache.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/completion.h>
#include <asm/sn/intr.h>
#include <asm/sn/sn_sal.h>
#include <asm/kdebug.h>
#include <asm/uaccess.h>
#include <asm/sn/xpc.h>
/* define two XPC debug device structures to be used with dev_dbg() et al */
struct device_driver xpc_dbg_name = {
.name = "xpc"
};
struct device xpc_part_dbg_subname = {
.bus_id = {0}, /* set to "part" at xpc_init() time */
.driver = &xpc_dbg_name
};
struct device xpc_chan_dbg_subname = {
.bus_id = {0}, /* set to "chan" at xpc_init() time */
.driver = &xpc_dbg_name
};
struct device *xpc_part = &xpc_part_dbg_subname;
struct device *xpc_chan = &xpc_chan_dbg_subname;
static int xpc_kdebug_ignore;
/* systune related variables for /proc/sys directories */
static int xpc_hb_interval = XPC_HB_DEFAULT_INTERVAL;
static int xpc_hb_min_interval = 1;
static int xpc_hb_max_interval = 10;
static int xpc_hb_check_interval = XPC_HB_CHECK_DEFAULT_INTERVAL;
static int xpc_hb_check_min_interval = 10;
static int xpc_hb_check_max_interval = 120;
int xpc_disengage_request_timelimit = XPC_DISENGAGE_REQUEST_DEFAULT_TIMELIMIT;
static int xpc_disengage_request_min_timelimit = 0;
static int xpc_disengage_request_max_timelimit = 120;
static ctl_table xpc_sys_xpc_hb_dir[] = {
{
.ctl_name = CTL_UNNUMBERED,
.procname = "hb_interval",
.data = &xpc_hb_interval,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &xpc_hb_min_interval,
.extra2 = &xpc_hb_max_interval
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "hb_check_interval",
.data = &xpc_hb_check_interval,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &xpc_hb_check_min_interval,
.extra2 = &xpc_hb_check_max_interval
},
{}
};
static ctl_table xpc_sys_xpc_dir[] = {
{
.ctl_name = CTL_UNNUMBERED,
.procname = "hb",
.mode = 0555,
.child = xpc_sys_xpc_hb_dir
},
{
.ctl_name = CTL_UNNUMBERED,
.procname = "disengage_request_timelimit",
.data = &xpc_disengage_request_timelimit,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &xpc_disengage_request_min_timelimit,
.extra2 = &xpc_disengage_request_max_timelimit
},
{}
};
static ctl_table xpc_sys_dir[] = {
{
.ctl_name = CTL_UNNUMBERED,
.procname = "xpc",
.mode = 0555,
.child = xpc_sys_xpc_dir
},
{}
};
static struct ctl_table_header *xpc_sysctl;
/* non-zero if any remote partition disengage request was timed out */
int xpc_disengage_request_timedout;
/* #of IRQs received */
static atomic_t xpc_act_IRQ_rcvd;
/* IRQ handler notifies this wait queue on receipt of an IRQ */
static DECLARE_WAIT_QUEUE_HEAD(xpc_act_IRQ_wq);
static unsigned long xpc_hb_check_timeout;
/* notification that the xpc_hb_checker thread has exited */
static DECLARE_COMPLETION(xpc_hb_checker_exited);
/* notification that the xpc_discovery thread has exited */
static DECLARE_COMPLETION(xpc_discovery_exited);
static struct timer_list xpc_hb_timer;
static void xpc_kthread_waitmsgs(struct xpc_partition *, struct xpc_channel *);
static int xpc_system_reboot(struct notifier_block *, unsigned long, void *);
static struct notifier_block xpc_reboot_notifier = {
.notifier_call = xpc_system_reboot,
};
static int xpc_system_die(struct notifier_block *, unsigned long, void *);
static struct notifier_block xpc_die_notifier = {
.notifier_call = xpc_system_die,
};
/*
* Timer function to enforce the timelimit on the partition disengage request.
*/
static void
xpc_timeout_partition_disengage_request(unsigned long data)
{
struct xpc_partition *part = (struct xpc_partition *) data;
DBUG_ON(jiffies < part->disengage_request_timeout);
(void) xpc_partition_disengaged(part);
DBUG_ON(part->disengage_request_timeout != 0);
DBUG_ON(xpc_partition_engaged(1UL << XPC_PARTID(part)) != 0);
}
/*
* Notify the heartbeat check thread that an IRQ has been received.
*/
static irqreturn_t
xpc_act_IRQ_handler(int irq, void *dev_id)
{
atomic_inc(&xpc_act_IRQ_rcvd);
wake_up_interruptible(&xpc_act_IRQ_wq);
return IRQ_HANDLED;
}
/*
* Timer to produce the heartbeat. The timer structures function is
* already set when this is initially called. A tunable is used to
* specify when the next timeout should occur.
*/
static void
xpc_hb_beater(unsigned long dummy)
{
xpc_vars->heartbeat++;
if (jiffies >= xpc_hb_check_timeout) {
wake_up_interruptible(&xpc_act_IRQ_wq);
}
xpc_hb_timer.expires = jiffies + (xpc_hb_interval * HZ);
add_timer(&xpc_hb_timer);
}
/*
* This thread is responsible for nearly all of the partition
* activation/deactivation.
*/
static int
xpc_hb_checker(void *ignore)
{
int last_IRQ_count = 0;
int new_IRQ_count;
int force_IRQ=0;
/* this thread was marked active by xpc_hb_init() */
daemonize(XPC_HB_CHECK_THREAD_NAME);
set_cpus_allowed(current, cpumask_of_cpu(XPC_HB_CHECK_CPU));
xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ);
while (!(volatile int) xpc_exiting) {
dev_dbg(xpc_part, "woke up with %d ticks rem; %d IRQs have "
"been received\n",
(int) (xpc_hb_check_timeout - jiffies),
atomic_read(&xpc_act_IRQ_rcvd) - last_IRQ_count);
/* checking of remote heartbeats is skewed by IRQ handling */
if (jiffies >= xpc_hb_check_timeout) {
dev_dbg(xpc_part, "checking remote heartbeats\n");
xpc_check_remote_hb();
/*
* We need to periodically recheck to ensure no
* IPI/AMO pairs have been missed. That check
* must always reset xpc_hb_check_timeout.
*/
force_IRQ = 1;
}
/* check for outstanding IRQs */
new_IRQ_count = atomic_read(&xpc_act_IRQ_rcvd);
if (last_IRQ_count < new_IRQ_count || force_IRQ != 0) {
force_IRQ = 0;
dev_dbg(xpc_part, "found an IRQ to process; will be "
"resetting xpc_hb_check_timeout\n");
last_IRQ_count += xpc_identify_act_IRQ_sender();
if (last_IRQ_count < new_IRQ_count) {
/* retry once to help avoid missing AMO */
(void) xpc_identify_act_IRQ_sender();
}
last_IRQ_count = new_IRQ_count;
xpc_hb_check_timeout = jiffies +
(xpc_hb_check_interval * HZ);
}
/* wait for IRQ or timeout */
(void) wait_event_interruptible(xpc_act_IRQ_wq,
(last_IRQ_count < atomic_read(&xpc_act_IRQ_rcvd) ||
jiffies >= xpc_hb_check_timeout ||
(volatile int) xpc_exiting));
}
dev_dbg(xpc_part, "heartbeat checker is exiting\n");
/* mark this thread as having exited */
complete(&xpc_hb_checker_exited);
return 0;
}
/*
* This thread will attempt to discover other partitions to activate
* based on info provided by SAL. This new thread is short lived and
* will exit once discovery is complete.
*/
static int
xpc_initiate_discovery(void *ignore)
{
daemonize(XPC_DISCOVERY_THREAD_NAME);
xpc_discovery();
dev_dbg(xpc_part, "discovery thread is exiting\n");
/* mark this thread as having exited */
complete(&xpc_discovery_exited);
return 0;
}
/*
* Establish first contact with the remote partititon. This involves pulling
* the XPC per partition variables from the remote partition and waiting for
* the remote partition to pull ours.
*/
static enum xpc_retval
xpc_make_first_contact(struct xpc_partition *part)
{
enum xpc_retval ret;
while ((ret = xpc_pull_remote_vars_part(part)) != xpcSuccess) {
if (ret != xpcRetry) {
XPC_DEACTIVATE_PARTITION(part, ret);
return ret;
}
dev_dbg(xpc_chan, "waiting to make first contact with "
"partition %d\n", XPC_PARTID(part));
/* wait a 1/4 of a second or so */
(void) msleep_interruptible(250);
if (part->act_state == XPC_P_DEACTIVATING) {
return part->reason;
}
}
return xpc_mark_partition_active(part);
}
/*
* The first kthread assigned to a newly activated partition is the one
* created by XPC HB with which it calls xpc_partition_up(). XPC hangs on to
* that kthread until the partition is brought down, at which time that kthread
* returns back to XPC HB. (The return of that kthread will signify to XPC HB
* that XPC has dismantled all communication infrastructure for the associated
* partition.) This kthread becomes the channel manager for that partition.
*
* Each active partition has a channel manager, who, besides connecting and
* disconnecting channels, will ensure that each of the partition's connected
* channels has the required number of assigned kthreads to get the work done.
*/
static void
xpc_channel_mgr(struct xpc_partition *part)
{
while (part->act_state != XPC_P_DEACTIVATING ||
atomic_read(&part->nchannels_active) > 0 ||
!xpc_partition_disengaged(part)) {
xpc_process_channel_activity(part);
/*
* Wait until we've been requested to activate kthreads or
* all of the channel's message queues have been torn down or
* a signal is pending.
*
* The channel_mgr_requests is set to 1 after being awakened,
* This is done to prevent the channel mgr from making one pass
* through the loop for each request, since he will
* be servicing all the requests in one pass. The reason it's
* set to 1 instead of 0 is so that other kthreads will know
* that the channel mgr is running and won't bother trying to
* wake him up.
*/
atomic_dec(&part->channel_mgr_requests);
(void) wait_event_interruptible(part->channel_mgr_wq,
(atomic_read(&part->channel_mgr_requests) > 0 ||
(volatile u64) part->local_IPI_amo != 0 ||
((volatile u8) part->act_state ==
XPC_P_DEACTIVATING &&
atomic_read(&part->nchannels_active) == 0 &&
xpc_partition_disengaged(part))));
atomic_set(&part->channel_mgr_requests, 1);
// >>> Does it need to wakeup periodically as well? In case we
// >>> miscalculated the #of kthreads to wakeup or create?
}
}
/*
* When XPC HB determines that a partition has come up, it will create a new
* kthread and that kthread will call this function to attempt to set up the
* basic infrastructure used for Cross Partition Communication with the newly
* upped partition.
*
* The kthread that was created by XPC HB and which setup the XPC
* infrastructure will remain assigned to the partition until the partition
* goes down. At which time the kthread will teardown the XPC infrastructure
* and then exit.
*
* XPC HB will put the remote partition's XPC per partition specific variables
* physical address into xpc_partitions[partid].remote_vars_part_pa prior to
* calling xpc_partition_up().
*/
static void
xpc_partition_up(struct xpc_partition *part)
{
DBUG_ON(part->channels != NULL);
dev_dbg(xpc_chan, "activating partition %d\n", XPC_PARTID(part));
if (xpc_setup_infrastructure(part) != xpcSuccess) {
return;
}
/*
* The kthread that XPC HB called us with will become the
* channel manager for this partition. It will not return
* back to XPC HB until the partition's XPC infrastructure
* has been dismantled.
*/
(void) xpc_part_ref(part); /* this will always succeed */
if (xpc_make_first_contact(part) == xpcSuccess) {
xpc_channel_mgr(part);
}
xpc_part_deref(part);
xpc_teardown_infrastructure(part);
}
static int
xpc_activating(void *__partid)
{
partid_t partid = (u64) __partid;
struct xpc_partition *part = &xpc_partitions[partid];
unsigned long irq_flags;
struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
int ret;
DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
spin_lock_irqsave(&part->act_lock, irq_flags);
if (part->act_state == XPC_P_DEACTIVATING) {
part->act_state = XPC_P_INACTIVE;
spin_unlock_irqrestore(&part->act_lock, irq_flags);
part->remote_rp_pa = 0;
return 0;
}
/* indicate the thread is activating */
DBUG_ON(part->act_state != XPC_P_ACTIVATION_REQ);
part->act_state = XPC_P_ACTIVATING;
XPC_SET_REASON(part, 0, 0);
spin_unlock_irqrestore(&part->act_lock, irq_flags);
dev_dbg(xpc_part, "bringing partition %d up\n", partid);
daemonize("xpc%02d", partid);
/*
* This thread needs to run at a realtime priority to prevent a
* significant performance degradation.
*/
ret = sched_setscheduler(current, SCHED_FIFO, &param);
if (ret != 0) {
dev_warn(xpc_part, "unable to set pid %d to a realtime "
"priority, ret=%d\n", current->pid, ret);
}
/* allow this thread and its children to run on any CPU */
set_cpus_allowed(current, CPU_MASK_ALL);
/*
* Register the remote partition's AMOs with SAL so it can handle
* and cleanup errors within that address range should the remote
* partition go down. We don't unregister this range because it is
* difficult to tell when outstanding writes to the remote partition
* are finished and thus when it is safe to unregister. This should
* not result in wasted space in the SAL xp_addr_region table because
* we should get the same page for remote_amos_page_pa after module
* reloads and system reboots.
*/
if (sn_register_xp_addr_region(part->remote_amos_page_pa,
PAGE_SIZE, 1) < 0) {
dev_warn(xpc_part, "xpc_partition_up(%d) failed to register "
"xp_addr region\n", partid);
spin_lock_irqsave(&part->act_lock, irq_flags);
part->act_state = XPC_P_INACTIVE;
XPC_SET_REASON(part, xpcPhysAddrRegFailed, __LINE__);
spin_unlock_irqrestore(&part->act_lock, irq_flags);
part->remote_rp_pa = 0;
return 0;
}
xpc_allow_hb(partid, xpc_vars);
xpc_IPI_send_activated(part);
/*
* xpc_partition_up() holds this thread and marks this partition as
* XPC_P_ACTIVE by calling xpc_hb_mark_active().
*/
(void) xpc_partition_up(part);
xpc_disallow_hb(partid, xpc_vars);
xpc_mark_partition_inactive(part);
if (part->reason == xpcReactivating) {
/* interrupting ourselves results in activating partition */
xpc_IPI_send_reactivate(part);
}
return 0;
}
void
xpc_activate_partition(struct xpc_partition *part)
{
partid_t partid = XPC_PARTID(part);
unsigned long irq_flags;
pid_t pid;
spin_lock_irqsave(&part->act_lock, irq_flags);
DBUG_ON(part->act_state != XPC_P_INACTIVE);
part->act_state = XPC_P_ACTIVATION_REQ;
XPC_SET_REASON(part, xpcCloneKThread, __LINE__);
spin_unlock_irqrestore(&part->act_lock, irq_flags);
pid = kernel_thread(xpc_activating, (void *) ((u64) partid), 0);
if (unlikely(pid <= 0)) {
spin_lock_irqsave(&part->act_lock, irq_flags);
part->act_state = XPC_P_INACTIVE;
XPC_SET_REASON(part, xpcCloneKThreadFailed, __LINE__);
spin_unlock_irqrestore(&part->act_lock, irq_flags);
}
}
/*
* Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
* partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
* than one partition, we use an AMO_t structure per partition to indicate
* whether a partition has sent an IPI or not. >>> If it has, then wake up the
* associated kthread to handle it.
*
* All SGI_XPC_NOTIFY IRQs received by XPC are the result of IPIs sent by XPC
* running on other partitions.
*
* Noteworthy Arguments:
*
* irq - Interrupt ReQuest number. NOT USED.
*
* dev_id - partid of IPI's potential sender.
*/
irqreturn_t
xpc_notify_IRQ_handler(int irq, void *dev_id)
{
partid_t partid = (partid_t) (u64) dev_id;
struct xpc_partition *part = &xpc_partitions[partid];
DBUG_ON(partid <= 0 || partid >= XP_MAX_PARTITIONS);
if (xpc_part_ref(part)) {
xpc_check_for_channel_activity(part);
xpc_part_deref(part);
}
return IRQ_HANDLED;
}
/*
* Check to see if xpc_notify_IRQ_handler() dropped any IPIs on the floor
* because the write to their associated IPI amo completed after the IRQ/IPI
* was received.
*/
void
xpc_dropped_IPI_check(struct xpc_partition *part)
{
if (xpc_part_ref(part)) {
xpc_check_for_channel_activity(part);
part->dropped_IPI_timer.expires = jiffies +
XPC_P_DROPPED_IPI_WAIT;
add_timer(&part->dropped_IPI_timer);
xpc_part_deref(part);
}
}
void
xpc_activate_kthreads(struct xpc_channel *ch, int needed)
{
int idle = atomic_read(&ch->kthreads_idle);
int assigned = atomic_read(&ch->kthreads_assigned);
int wakeup;
DBUG_ON(needed <= 0);
if (idle > 0) {
wakeup = (needed > idle) ? idle : needed;
needed -= wakeup;
dev_dbg(xpc_chan, "wakeup %d idle kthreads, partid=%d, "
"channel=%d\n", wakeup, ch->partid, ch->number);
/* only wakeup the requested number of kthreads */
wake_up_nr(&ch->idle_wq, wakeup);
}
if (needed <= 0) {
return;
}
if (needed + assigned > ch->kthreads_assigned_limit) {
needed = ch->kthreads_assigned_limit - assigned;
// >>>should never be less than 0
if (needed <= 0) {
return;
}
}
dev_dbg(xpc_chan, "create %d new kthreads, partid=%d, channel=%d\n",
needed, ch->partid, ch->number);
xpc_create_kthreads(ch, needed, 0);
}
/*
* This function is where XPC's kthreads wait for messages to deliver.
*/
static void
xpc_kthread_waitmsgs(struct xpc_partition *part, struct xpc_channel *ch)
{
do {
/* deliver messages to their intended recipients */
while ((volatile s64) ch->w_local_GP.get <
(volatile s64) ch->w_remote_GP.put &&
!((volatile u32) ch->flags &
XPC_C_DISCONNECTING)) {
xpc_deliver_msg(ch);
}
if (atomic_inc_return(&ch->kthreads_idle) >
ch->kthreads_idle_limit) {
/* too many idle kthreads on this channel */
atomic_dec(&ch->kthreads_idle);
break;
}
dev_dbg(xpc_chan, "idle kthread calling "
"wait_event_interruptible_exclusive()\n");
(void) wait_event_interruptible_exclusive(ch->idle_wq,
((volatile s64) ch->w_local_GP.get <
(volatile s64) ch->w_remote_GP.put ||
((volatile u32) ch->flags &
XPC_C_DISCONNECTING)));
atomic_dec(&ch->kthreads_idle);
} while (!((volatile u32) ch->flags & XPC_C_DISCONNECTING));
}
static int
xpc_daemonize_kthread(void *args)
{
partid_t partid = XPC_UNPACK_ARG1(args);
u16 ch_number = XPC_UNPACK_ARG2(args);
struct xpc_partition *part = &xpc_partitions[partid];
struct xpc_channel *ch;
int n_needed;
unsigned long irq_flags;
daemonize("xpc%02dc%d", partid, ch_number);
dev_dbg(xpc_chan, "kthread starting, partid=%d, channel=%d\n",
partid, ch_number);
ch = &part->channels[ch_number];
if (!(ch->flags & XPC_C_DISCONNECTING)) {
/* let registerer know that connection has been established */
spin_lock_irqsave(&ch->lock, irq_flags);
if (!(ch->flags & XPC_C_CONNECTEDCALLOUT)) {
ch->flags |= XPC_C_CONNECTEDCALLOUT;
spin_unlock_irqrestore(&ch->lock, irq_flags);
xpc_connected_callout(ch);
spin_lock_irqsave(&ch->lock, irq_flags);
ch->flags |= XPC_C_CONNECTEDCALLOUT_MADE;
spin_unlock_irqrestore(&ch->lock, irq_flags);
/*
* It is possible that while the callout was being
* made that the remote partition sent some messages.
* If that is the case, we may need to activate
* additional kthreads to help deliver them. We only
* need one less than total #of messages to deliver.
*/
n_needed = ch->w_remote_GP.put - ch->w_local_GP.get - 1;
if (n_needed > 0 &&
!(ch->flags & XPC_C_DISCONNECTING)) {
xpc_activate_kthreads(ch, n_needed);
}
} else {
spin_unlock_irqrestore(&ch->lock, irq_flags);
}
xpc_kthread_waitmsgs(part, ch);
}
/* let registerer know that connection is disconnecting */
spin_lock_irqsave(&ch->lock, irq_flags);
if ((ch->flags & XPC_C_CONNECTEDCALLOUT_MADE) &&
!(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) {
ch->flags |= XPC_C_DISCONNECTINGCALLOUT;
spin_unlock_irqrestore(&ch->lock, irq_flags);
xpc_disconnect_callout(ch, xpcDisconnecting);
spin_lock_irqsave(&ch->lock, irq_flags);
ch->flags |= XPC_C_DISCONNECTINGCALLOUT_MADE;
}
spin_unlock_irqrestore(&ch->lock, irq_flags);
if (atomic_dec_return(&ch->kthreads_assigned) == 0) {
if (atomic_dec_return(&part->nchannels_engaged) == 0) {
xpc_mark_partition_disengaged(part);
xpc_IPI_send_disengage(part);
}
}
xpc_msgqueue_deref(ch);
dev_dbg(xpc_chan, "kthread exiting, partid=%d, channel=%d\n",
partid, ch_number);
xpc_part_deref(part);
return 0;
}
/*
* For each partition that XPC has established communications with, there is
* a minimum of one kernel thread assigned to perform any operation that
* may potentially sleep or block (basically the callouts to the asynchronous
* functions registered via xpc_connect()).
*
* Additional kthreads are created and destroyed by XPC as the workload
* demands.
*
* A kthread is assigned to one of the active channels that exists for a given
* partition.
*/
void
xpc_create_kthreads(struct xpc_channel *ch, int needed,
int ignore_disconnecting)
{
unsigned long irq_flags;
pid_t pid;
u64 args = XPC_PACK_ARGS(ch->partid, ch->number);
struct xpc_partition *part = &xpc_partitions[ch->partid];
while (needed-- > 0) {
/*
* The following is done on behalf of the newly created
* kthread. That kthread is responsible for doing the
* counterpart to the following before it exits.
*/
if (ignore_disconnecting) {
if (!atomic_inc_not_zero(&ch->kthreads_assigned)) {
/* kthreads assigned had gone to zero */
BUG_ON(!(ch->flags &
XPC_C_DISCONNECTINGCALLOUT_MADE));
break;
}
} else if (ch->flags & XPC_C_DISCONNECTING) {
break;
} else if (atomic_inc_return(&ch->kthreads_assigned) == 1) {
if (atomic_inc_return(&part->nchannels_engaged) == 1)
xpc_mark_partition_engaged(part);
}
(void) xpc_part_ref(part);
xpc_msgqueue_ref(ch);
pid = kernel_thread(xpc_daemonize_kthread, (void *) args, 0);
if (pid < 0) {
/* the fork failed */
/*
* NOTE: if (ignore_disconnecting &&
* !(ch->flags & XPC_C_DISCONNECTINGCALLOUT)) is true,
* then we'll deadlock if all other kthreads assigned
* to this channel are blocked in the channel's
* registerer, because the only thing that will unblock
* them is the xpcDisconnecting callout that this
* failed kernel_thread would have made.
*/
if (atomic_dec_return(&ch->kthreads_assigned) == 0 &&
atomic_dec_return(&part->nchannels_engaged) == 0) {
xpc_mark_partition_disengaged(part);
xpc_IPI_send_disengage(part);
}
xpc_msgqueue_deref(ch);
xpc_part_deref(part);
if (atomic_read(&ch->kthreads_assigned) <
ch->kthreads_idle_limit) {
/*
* Flag this as an error only if we have an
* insufficient #of kthreads for the channel
* to function.
*/
spin_lock_irqsave(&ch->lock, irq_flags);
XPC_DISCONNECT_CHANNEL(ch, xpcLackOfResources,
&irq_flags);
spin_unlock_irqrestore(&ch->lock, irq_flags);
}
break;
}
ch->kthreads_created++; // >>> temporary debug only!!!
}
}
void
xpc_disconnect_wait(int ch_number)
{
unsigned long irq_flags;
partid_t partid;
struct xpc_partition *part;
struct xpc_channel *ch;
int wakeup_channel_mgr;
/* now wait for all callouts to the caller's function to cease */
for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
part = &xpc_partitions[partid];
if (!xpc_part_ref(part)) {
continue;
}
ch = &part->channels[ch_number];
if (!(ch->flags & XPC_C_WDISCONNECT)) {
xpc_part_deref(part);
continue;
}
wait_for_completion(&ch->wdisconnect_wait);
spin_lock_irqsave(&ch->lock, irq_flags);
DBUG_ON(!(ch->flags & XPC_C_DISCONNECTED));
wakeup_channel_mgr = 0;
if (ch->delayed_IPI_flags) {
if (part->act_state != XPC_P_DEACTIVATING) {
spin_lock(&part->IPI_lock);
XPC_SET_IPI_FLAGS(part->local_IPI_amo,
ch->number, ch->delayed_IPI_flags);
spin_unlock(&part->IPI_lock);
wakeup_channel_mgr = 1;
}
ch->delayed_IPI_flags = 0;
}
ch->flags &= ~XPC_C_WDISCONNECT;
spin_unlock_irqrestore(&ch->lock, irq_flags);
if (wakeup_channel_mgr) {
xpc_wakeup_channel_mgr(part);
}
xpc_part_deref(part);
}
}
static void
xpc_do_exit(enum xpc_retval reason)
{
partid_t partid;
int active_part_count, printed_waiting_msg = 0;
struct xpc_partition *part;
unsigned long printmsg_time, disengage_request_timeout = 0;
/* a 'rmmod XPC' and a 'reboot' cannot both end up here together */
DBUG_ON(xpc_exiting == 1);
/*
* Let the heartbeat checker thread and the discovery thread
* (if one is running) know that they should exit. Also wake up
* the heartbeat checker thread in case it's sleeping.
*/
xpc_exiting = 1;
wake_up_interruptible(&xpc_act_IRQ_wq);
/* ignore all incoming interrupts */
free_irq(SGI_XPC_ACTIVATE, NULL);
/* wait for the discovery thread to exit */
wait_for_completion(&xpc_discovery_exited);
/* wait for the heartbeat checker thread to exit */
wait_for_completion(&xpc_hb_checker_exited);
/* sleep for a 1/3 of a second or so */
(void) msleep_interruptible(300);
/* wait for all partitions to become inactive */
printmsg_time = jiffies + (XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
xpc_disengage_request_timedout = 0;
do {
active_part_count = 0;
for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
part = &xpc_partitions[partid];
if (xpc_partition_disengaged(part) &&
part->act_state == XPC_P_INACTIVE) {
continue;
}
active_part_count++;
XPC_DEACTIVATE_PARTITION(part, reason);
if (part->disengage_request_timeout >
disengage_request_timeout) {
disengage_request_timeout =
part->disengage_request_timeout;
}
}
if (xpc_partition_engaged(-1UL)) {
if (time_after(jiffies, printmsg_time)) {
dev_info(xpc_part, "waiting for remote "
"partitions to disengage, timeout in "
"%ld seconds\n",
(disengage_request_timeout - jiffies)
/ HZ);
printmsg_time = jiffies +
(XPC_DISENGAGE_PRINTMSG_INTERVAL * HZ);
printed_waiting_msg = 1;
}
} else if (active_part_count > 0) {
if (printed_waiting_msg) {
dev_info(xpc_part, "waiting for local partition"
" to disengage\n");
printed_waiting_msg = 0;
}
} else {
if (!xpc_disengage_request_timedout) {
dev_info(xpc_part, "all partitions have "
"disengaged\n");
}
break;
}
/* sleep for a 1/3 of a second or so */
(void) msleep_interruptible(300);
} while (1);
DBUG_ON(xpc_partition_engaged(-1UL));
/* indicate to others that our reserved page is uninitialized */
xpc_rsvd_page->vars_pa = 0;
/* now it's time to eliminate our heartbeat */
del_timer_sync(&xpc_hb_timer);
DBUG_ON(xpc_vars->heartbeating_to_mask != 0);
if (reason == xpcUnloading) {
/* take ourselves off of the reboot_notifier_list */
(void) unregister_reboot_notifier(&xpc_reboot_notifier);
/* take ourselves off of the die_notifier list */
(void) unregister_die_notifier(&xpc_die_notifier);
}
/* close down protections for IPI operations */
xpc_restrict_IPI_ops();
/* clear the interface to XPC's functions */
xpc_clear_interface();
if (xpc_sysctl) {
unregister_sysctl_table(xpc_sysctl);
}
kfree(xpc_remote_copy_buffer_base);
}
/*
* This function is called when the system is being rebooted.
*/
static int
xpc_system_reboot(struct notifier_block *nb, unsigned long event, void *unused)
{
enum xpc_retval reason;
switch (event) {
case SYS_RESTART:
reason = xpcSystemReboot;
break;
case SYS_HALT:
reason = xpcSystemHalt;
break;
case SYS_POWER_OFF:
reason = xpcSystemPoweroff;
break;
default:
reason = xpcSystemGoingDown;
}
xpc_do_exit(reason);
return NOTIFY_DONE;
}
/*
* Notify other partitions to disengage from all references to our memory.
*/
static void
xpc_die_disengage(void)
{
struct xpc_partition *part;
partid_t partid;
unsigned long engaged;
long time, printmsg_time, disengage_request_timeout;
/* keep xpc_hb_checker thread from doing anything (just in case) */
xpc_exiting = 1;
xpc_vars->heartbeating_to_mask = 0; /* indicate we're deactivated */
for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
part = &xpc_partitions[partid];
if (!XPC_SUPPORTS_DISENGAGE_REQUEST(part->
remote_vars_version)) {
/* just in case it was left set by an earlier XPC */
xpc_clear_partition_engaged(1UL << partid);
continue;
}
if (xpc_partition_engaged(1UL << partid) ||
part->act_state != XPC_P_INACTIVE) {
xpc_request_partition_disengage(part);
xpc_mark_partition_disengaged(part);
xpc_IPI_send_disengage(part);
}
}
time = rtc_time();
printmsg_time = time +
(XPC_DISENGAGE_PRINTMSG_INTERVAL * sn_rtc_cycles_per_second);
disengage_request_timeout = time +
(xpc_disengage_request_timelimit * sn_rtc_cycles_per_second);
/* wait for all other partitions to disengage from us */
while (1) {
engaged = xpc_partition_engaged(-1UL);
if (!engaged) {
dev_info(xpc_part, "all partitions have disengaged\n");
break;
}
time = rtc_time();
if (time >= disengage_request_timeout) {
for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
if (engaged & (1UL << partid)) {
dev_info(xpc_part, "disengage from "
"remote partition %d timed "
"out\n", partid);
}
}
break;
}
if (time >= printmsg_time) {
dev_info(xpc_part, "waiting for remote partitions to "
"disengage, timeout in %ld seconds\n",
(disengage_request_timeout - time) /
sn_rtc_cycles_per_second);
printmsg_time = time +
(XPC_DISENGAGE_PRINTMSG_INTERVAL *
sn_rtc_cycles_per_second);
}
}
}
/*
* This function is called when the system is being restarted or halted due
* to some sort of system failure. If this is the case we need to notify the
* other partitions to disengage from all references to our memory.
* This function can also be called when our heartbeater could be offlined
* for a time. In this case we need to notify other partitions to not worry
* about the lack of a heartbeat.
*/
static int
xpc_system_die(struct notifier_block *nb, unsigned long event, void *unused)
{
switch (event) {
case DIE_MACHINE_RESTART:
case DIE_MACHINE_HALT:
xpc_die_disengage();
break;
case DIE_KDEBUG_ENTER:
/* Should lack of heartbeat be ignored by other partitions? */
if (!xpc_kdebug_ignore) {
break;
}
/* fall through */
case DIE_MCA_MONARCH_ENTER:
case DIE_INIT_MONARCH_ENTER:
xpc_vars->heartbeat++;
xpc_vars->heartbeat_offline = 1;
break;
case DIE_KDEBUG_LEAVE:
/* Is lack of heartbeat being ignored by other partitions? */
if (!xpc_kdebug_ignore) {
break;
}
/* fall through */
case DIE_MCA_MONARCH_LEAVE:
case DIE_INIT_MONARCH_LEAVE:
xpc_vars->heartbeat++;
xpc_vars->heartbeat_offline = 0;
break;
}
return NOTIFY_DONE;
}
int __init
xpc_init(void)
{
int ret;
partid_t partid;
struct xpc_partition *part;
pid_t pid;
size_t buf_size;
if (!ia64_platform_is("sn2")) {
return -ENODEV;
}
buf_size = max(XPC_RP_VARS_SIZE,
XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES);
xpc_remote_copy_buffer = xpc_kmalloc_cacheline_aligned(buf_size,
GFP_KERNEL, &xpc_remote_copy_buffer_base);
if (xpc_remote_copy_buffer == NULL)
return -ENOMEM;
snprintf(xpc_part->bus_id, BUS_ID_SIZE, "part");
snprintf(xpc_chan->bus_id, BUS_ID_SIZE, "chan");
xpc_sysctl = register_sysctl_table(xpc_sys_dir);
/*
* The first few fields of each entry of xpc_partitions[] need to
* be initialized now so that calls to xpc_connect() and
* xpc_disconnect() can be made prior to the activation of any remote
* partition. NOTE THAT NONE OF THE OTHER FIELDS BELONGING TO THESE
* ENTRIES ARE MEANINGFUL UNTIL AFTER AN ENTRY'S CORRESPONDING
* PARTITION HAS BEEN ACTIVATED.
*/
for (partid = 1; partid < XP_MAX_PARTITIONS; partid++) {
part = &xpc_partitions[partid];
DBUG_ON((u64) part != L1_CACHE_ALIGN((u64) part));
part->act_IRQ_rcvd = 0;
spin_lock_init(&part->act_lock);
part->act_state = XPC_P_INACTIVE;
XPC_SET_REASON(part, 0, 0);
init_timer(&part->disengage_request_timer);
part->disengage_request_timer.function =
xpc_timeout_partition_disengage_request;
part->disengage_request_timer.data = (unsigned long) part;
part->setup_state = XPC_P_UNSET;
init_waitqueue_head(&part->teardown_wq);
atomic_set(&part->references, 0);
}
/*
* Open up protections for IPI operations (and AMO operations on
* Shub 1.1 systems).
*/
xpc_allow_IPI_ops();
/*
* Interrupts being processed will increment this atomic variable and
* awaken the heartbeat thread which will process the interrupts.
*/
atomic_set(&xpc_act_IRQ_rcvd, 0);
/*
* This is safe to do before the xpc_hb_checker thread has started
* because the handler releases a wait queue. If an interrupt is
* received before the thread is waiting, it will not go to sleep,
* but rather immediately process the interrupt.
*/
ret = request_irq(SGI_XPC_ACTIVATE, xpc_act_IRQ_handler, 0,
"xpc hb", NULL);
if (ret != 0) {
dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
"errno=%d\n", -ret);
xpc_restrict_IPI_ops();
if (xpc_sysctl) {
unregister_sysctl_table(xpc_sysctl);
}
kfree(xpc_remote_copy_buffer_base);
return -EBUSY;
}
/*
* Fill the partition reserved page with the information needed by
* other partitions to discover we are alive and establish initial
* communications.
*/
xpc_rsvd_page = xpc_rsvd_page_init();
if (xpc_rsvd_page == NULL) {
dev_err(xpc_part, "could not setup our reserved page\n");
free_irq(SGI_XPC_ACTIVATE, NULL);
xpc_restrict_IPI_ops();
if (xpc_sysctl) {
unregister_sysctl_table(xpc_sysctl);
}
kfree(xpc_remote_copy_buffer_base);
return -EBUSY;
}
/* add ourselves to the reboot_notifier_list */
ret = register_reboot_notifier(&xpc_reboot_notifier);
if (ret != 0) {
dev_warn(xpc_part, "can't register reboot notifier\n");
}
/* add ourselves to the die_notifier list (i.e., ia64die_chain) */
ret = register_die_notifier(&xpc_die_notifier);
if (ret != 0) {
dev_warn(xpc_part, "can't register die notifier\n");
}
/*
* Set the beating to other partitions into motion. This is
* the last requirement for other partitions' discovery to
* initiate communications with us.
*/
init_timer(&xpc_hb_timer);
xpc_hb_timer.function = xpc_hb_beater;
xpc_hb_beater(0);
/*
* The real work-horse behind xpc. This processes incoming
* interrupts and monitors remote heartbeats.
*/
pid = kernel_thread(xpc_hb_checker, NULL, 0);
if (pid < 0) {
dev_err(xpc_part, "failed while forking hb check thread\n");
/* indicate to others that our reserved page is uninitialized */
xpc_rsvd_page->vars_pa = 0;
/* take ourselves off of the reboot_notifier_list */
(void) unregister_reboot_notifier(&xpc_reboot_notifier);
/* take ourselves off of the die_notifier list */
(void) unregister_die_notifier(&xpc_die_notifier);
del_timer_sync(&xpc_hb_timer);
free_irq(SGI_XPC_ACTIVATE, NULL);
xpc_restrict_IPI_ops();
if (xpc_sysctl) {
unregister_sysctl_table(xpc_sysctl);
}
kfree(xpc_remote_copy_buffer_base);
return -EBUSY;
}
/*
* Startup a thread that will attempt to discover other partitions to
* activate based on info provided by SAL. This new thread is short
* lived and will exit once discovery is complete.
*/
pid = kernel_thread(xpc_initiate_discovery, NULL, 0);
if (pid < 0) {
dev_err(xpc_part, "failed while forking discovery thread\n");
/* mark this new thread as a non-starter */
complete(&xpc_discovery_exited);
xpc_do_exit(xpcUnloading);
return -EBUSY;
}
/* set the interface to point at XPC's functions */
xpc_set_interface(xpc_initiate_connect, xpc_initiate_disconnect,
xpc_initiate_allocate, xpc_initiate_send,
xpc_initiate_send_notify, xpc_initiate_received,
xpc_initiate_partid_to_nasids);
return 0;
}
module_init(xpc_init);
void __exit
xpc_exit(void)
{
xpc_do_exit(xpcUnloading);
}
module_exit(xpc_exit);
MODULE_AUTHOR("Silicon Graphics, Inc.");
MODULE_DESCRIPTION("Cross Partition Communication (XPC) support");
MODULE_LICENSE("GPL");
module_param(xpc_hb_interval, int, 0);
MODULE_PARM_DESC(xpc_hb_interval, "Number of seconds between "
"heartbeat increments.");
module_param(xpc_hb_check_interval, int, 0);
MODULE_PARM_DESC(xpc_hb_check_interval, "Number of seconds between "
"heartbeat checks.");
module_param(xpc_disengage_request_timelimit, int, 0);
MODULE_PARM_DESC(xpc_disengage_request_timelimit, "Number of seconds to wait "
"for disengage request to complete.");
module_param(xpc_kdebug_ignore, int, 0);
MODULE_PARM_DESC(xpc_kdebug_ignore, "Should lack of heartbeat be ignored by "
"other partitions when dropping into kdebug.");