diff options
Diffstat (limited to 'drivers/misc/sgi-xp/xpc_main.c')
| -rw-r--r-- | drivers/misc/sgi-xp/xpc_main.c | 1431 |
1 files changed, 1431 insertions, 0 deletions
diff --git a/drivers/misc/sgi-xp/xpc_main.c b/drivers/misc/sgi-xp/xpc_main.c new file mode 100644 index 000000000000..bdb2cf1fcbcc --- /dev/null +++ b/drivers/misc/sgi-xp/xpc_main.c @@ -0,0 +1,1431 @@ +/* + * 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) 2004-2008 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 <linux/kdebug.h> +#include <asm/sn/intr.h> +#include <asm/sn/sn_sal.h> +#include <asm/uaccess.h> +#include "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(time_before(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 (time_after_eq(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)); + + /* set our heartbeating to other partitions into motion */ + xpc_hb_check_timeout = jiffies + (xpc_hb_check_interval * HZ); + xpc_hb_beater(0); + + 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 (time_after_eq(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) || + time_after_eq(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, ¶m); + 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 */ + ret = register_die_notifier(&xpc_die_notifier); + if (ret != 0) { + dev_warn(xpc_part, "can't register die notifier\n"); + } + + init_timer(&xpc_hb_timer); + xpc_hb_timer.function = xpc_hb_beater; + + /* + * 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."); + |