Merge branches 'for-4.4/upstream-fixes', 'for-4.5/async-suspend', 'for-4.5/container...

[mirror_ubuntu-artful-kernel.git] / drivers / staging / lustre / lnet / lnet / router.c

/*
 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
 *
 * Copyright (c) 2011, 2012, Intel Corporation.
 *
 *   This file is part of Portals
 *   http://sourceforge.net/projects/sandiaportals/
 *
 *   Portals is free software; you can redistribute it and/or
 *   modify it under the terms of version 2 of the GNU General Public
 *   License as published by the Free Software Foundation.
 *
 *   Portals is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with Portals; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#define DEBUG_SUBSYSTEM S_LNET
#include "../../include/linux/lnet/lib-lnet.h"

#define LNET_NRB_TINY_MIN       512     /* min value for each CPT */
#define LNET_NRB_TINY           (LNET_NRB_TINY_MIN * 4)
#define LNET_NRB_SMALL_MIN      4096    /* min value for each CPT */
#define LNET_NRB_SMALL          (LNET_NRB_SMALL_MIN * 4)
#define LNET_NRB_LARGE_MIN      256     /* min value for each CPT */
#define LNET_NRB_LARGE          (LNET_NRB_LARGE_MIN * 4)

static char *forwarding = "";
module_param(forwarding, charp, 0444);
MODULE_PARM_DESC(forwarding, "Explicitly enable/disable forwarding between networks");

static int tiny_router_buffers;
module_param(tiny_router_buffers, int, 0444);
MODULE_PARM_DESC(tiny_router_buffers, "# of 0 payload messages to buffer in the router");
static int small_router_buffers;
module_param(small_router_buffers, int, 0444);
MODULE_PARM_DESC(small_router_buffers, "# of small (1 page) messages to buffer in the router");
static int large_router_buffers;
module_param(large_router_buffers, int, 0444);
MODULE_PARM_DESC(large_router_buffers, "# of large messages to buffer in the router");
static int peer_buffer_credits;
module_param(peer_buffer_credits, int, 0444);
MODULE_PARM_DESC(peer_buffer_credits, "# router buffer credits per peer");

static int auto_down = 1;
module_param(auto_down, int, 0444);
MODULE_PARM_DESC(auto_down, "Automatically mark peers down on comms error");

int
lnet_peer_buffer_credits(lnet_ni_t *ni)
{
        /* NI option overrides LNet default */
        if (ni->ni_peerrtrcredits > 0)
                return ni->ni_peerrtrcredits;
        if (peer_buffer_credits > 0)
                return peer_buffer_credits;

        /* As an approximation, allow this peer the same number of router
         * buffers as it is allowed outstanding sends */
        return ni->ni_peertxcredits;
}

/* forward ref's */
static int lnet_router_checker(void *);

static int check_routers_before_use;
module_param(check_routers_before_use, int, 0444);
MODULE_PARM_DESC(check_routers_before_use, "Assume routers are down and ping them before use");

int avoid_asym_router_failure = 1;
module_param(avoid_asym_router_failure, int, 0644);
MODULE_PARM_DESC(avoid_asym_router_failure, "Avoid asymmetrical router failures (0 to disable)");

static int dead_router_check_interval = 60;
module_param(dead_router_check_interval, int, 0644);
MODULE_PARM_DESC(dead_router_check_interval, "Seconds between dead router health checks (<= 0 to disable)");

static int live_router_check_interval = 60;
module_param(live_router_check_interval, int, 0644);
MODULE_PARM_DESC(live_router_check_interval, "Seconds between live router health checks (<= 0 to disable)");

static int router_ping_timeout = 50;
module_param(router_ping_timeout, int, 0644);
MODULE_PARM_DESC(router_ping_timeout, "Seconds to wait for the reply to a router health query");

int
lnet_peers_start_down(void)
{
        return check_routers_before_use;
}

void
lnet_notify_locked(lnet_peer_t *lp, int notifylnd, int alive,
                   unsigned long when)
{
        if (time_before(when, lp->lp_timestamp)) { /* out of date information */
                CDEBUG(D_NET, "Out of date\n");
                return;
        }

        lp->lp_timestamp = when;                /* update timestamp */
        lp->lp_ping_deadline = 0;              /* disable ping timeout */

        if (lp->lp_alive_count != 0 &&    /* got old news */
            (!lp->lp_alive) == (!alive)) {      /* new date for old news */
                CDEBUG(D_NET, "Old news\n");
                return;
        }

        /* Flag that notification is outstanding */

        lp->lp_alive_count++;
        lp->lp_alive = !(!alive);              /* 1 bit! */
        lp->lp_notify = 1;
        lp->lp_notifylnd |= notifylnd;
        if (lp->lp_alive)
                lp->lp_ping_feats = LNET_PING_FEAT_INVAL; /* reset */

        CDEBUG(D_NET, "set %s %d\n", libcfs_nid2str(lp->lp_nid), alive);
}

static void
lnet_ni_notify_locked(lnet_ni_t *ni, lnet_peer_t *lp)
{
        int alive;
        int notifylnd;

        /* Notify only in 1 thread at any time to ensure ordered notification.
         * NB individual events can be missed; the only guarantee is that you
         * always get the most recent news */

        if (lp->lp_notifying || ni == NULL)
                return;

        lp->lp_notifying = 1;

        while (lp->lp_notify) {
                alive = lp->lp_alive;
                notifylnd = lp->lp_notifylnd;

                lp->lp_notifylnd = 0;
                lp->lp_notify    = 0;

                if (notifylnd && ni->ni_lnd->lnd_notify != NULL) {
                        lnet_net_unlock(lp->lp_cpt);

                        /* A new notification could happen now; I'll handle it
                         * when control returns to me */

                        (ni->ni_lnd->lnd_notify)(ni, lp->lp_nid, alive);

                        lnet_net_lock(lp->lp_cpt);
                }
        }

        lp->lp_notifying = 0;
}

static void
lnet_rtr_addref_locked(lnet_peer_t *lp)
{
        LASSERT(lp->lp_refcount > 0);
        LASSERT(lp->lp_rtr_refcount >= 0);

        /* lnet_net_lock must be exclusively locked */
        lp->lp_rtr_refcount++;
        if (lp->lp_rtr_refcount == 1) {
                struct list_head *pos;

                /* a simple insertion sort */
                list_for_each_prev(pos, &the_lnet.ln_routers) {
                        lnet_peer_t *rtr = list_entry(pos, lnet_peer_t,
                                                          lp_rtr_list);

                        if (rtr->lp_nid < lp->lp_nid)
                                break;
                }

                list_add(&lp->lp_rtr_list, pos);
                /* addref for the_lnet.ln_routers */
                lnet_peer_addref_locked(lp);
                the_lnet.ln_routers_version++;
        }
}

static void
lnet_rtr_decref_locked(lnet_peer_t *lp)
{
        LASSERT(lp->lp_refcount > 0);
        LASSERT(lp->lp_rtr_refcount > 0);

        /* lnet_net_lock must be exclusively locked */
        lp->lp_rtr_refcount--;
        if (lp->lp_rtr_refcount == 0) {
                LASSERT(list_empty(&lp->lp_routes));

                if (lp->lp_rcd != NULL) {
                        list_add(&lp->lp_rcd->rcd_list,
                                     &the_lnet.ln_rcd_deathrow);
                        lp->lp_rcd = NULL;
                }

                list_del(&lp->lp_rtr_list);
                /* decref for the_lnet.ln_routers */
                lnet_peer_decref_locked(lp);
                the_lnet.ln_routers_version++;
        }
}

lnet_remotenet_t *
lnet_find_net_locked(__u32 net)
{
        lnet_remotenet_t *rnet;
        struct list_head *tmp;
        struct list_head *rn_list;

        LASSERT(!the_lnet.ln_shutdown);

        rn_list = lnet_net2rnethash(net);
        list_for_each(tmp, rn_list) {
                rnet = list_entry(tmp, lnet_remotenet_t, lrn_list);

                if (rnet->lrn_net == net)
                        return rnet;
        }
        return NULL;
}

static void lnet_shuffle_seed(void)
{
        static int seeded;
        __u32 lnd_type, seed[2];
        struct timespec64 ts;
        lnet_ni_t *ni;
        struct list_head *tmp;

        if (seeded)
                return;

        cfs_get_random_bytes(seed, sizeof(seed));

        /* Nodes with small feet have little entropy
         * the NID for this node gives the most entropy in the low bits */
        list_for_each(tmp, &the_lnet.ln_nis) {
                ni = list_entry(tmp, lnet_ni_t, ni_list);
                lnd_type = LNET_NETTYP(LNET_NIDNET(ni->ni_nid));

                if (lnd_type != LOLND)
                        seed[0] ^= (LNET_NIDADDR(ni->ni_nid) | lnd_type);
        }

        ktime_get_ts64(&ts);
        cfs_srand(ts.tv_sec ^ seed[0], ts.tv_nsec ^ seed[1]);
        seeded = 1;
}

/* NB expects LNET_LOCK held */
static void
lnet_add_route_to_rnet(lnet_remotenet_t *rnet, lnet_route_t *route)
{
        unsigned int len = 0;
        unsigned int offset = 0;
        struct list_head *e;

        lnet_shuffle_seed();

        list_for_each(e, &rnet->lrn_routes) {
                len++;
        }

        /* len+1 positions to add a new entry, also prevents division by 0 */
        offset = cfs_rand() % (len + 1);
        list_for_each(e, &rnet->lrn_routes) {
                if (offset == 0)
                        break;
                offset--;
        }
        list_add(&route->lr_list, e);
        list_add(&route->lr_gwlist, &route->lr_gateway->lp_routes);

        the_lnet.ln_remote_nets_version++;
        lnet_rtr_addref_locked(route->lr_gateway);
}

int
lnet_add_route(__u32 net, unsigned int hops, lnet_nid_t gateway,
               unsigned int priority)
{
        struct list_head *e;
        lnet_remotenet_t *rnet;
        lnet_remotenet_t *rnet2;
        lnet_route_t *route;
        lnet_ni_t *ni;
        int add_route;
        int rc;

        CDEBUG(D_NET, "Add route: net %s hops %u priority %u gw %s\n",
               libcfs_net2str(net), hops, priority, libcfs_nid2str(gateway));

        if (gateway == LNET_NID_ANY ||
            LNET_NETTYP(LNET_NIDNET(gateway)) == LOLND ||
            net == LNET_NIDNET(LNET_NID_ANY) ||
            LNET_NETTYP(net) == LOLND ||
            LNET_NIDNET(gateway) == net ||
            hops < 1 || hops > 255)
                return -EINVAL;

        if (lnet_islocalnet(net))              /* it's a local network */
                return 0;                      /* ignore the route entry */

        /* Assume net, route, all new */
        LIBCFS_ALLOC(route, sizeof(*route));
        LIBCFS_ALLOC(rnet, sizeof(*rnet));
        if (route == NULL || rnet == NULL) {
                CERROR("Out of memory creating route %s %d %s\n",
                       libcfs_net2str(net), hops, libcfs_nid2str(gateway));
                if (route != NULL)
                        LIBCFS_FREE(route, sizeof(*route));
                if (rnet != NULL)
                        LIBCFS_FREE(rnet, sizeof(*rnet));
                return -ENOMEM;
        }

        INIT_LIST_HEAD(&rnet->lrn_routes);
        rnet->lrn_net = net;
        route->lr_hops = hops;
        route->lr_net = net;
        route->lr_priority = priority;

        lnet_net_lock(LNET_LOCK_EX);

        rc = lnet_nid2peer_locked(&route->lr_gateway, gateway, LNET_LOCK_EX);
        if (rc != 0) {
                lnet_net_unlock(LNET_LOCK_EX);

                LIBCFS_FREE(route, sizeof(*route));
                LIBCFS_FREE(rnet, sizeof(*rnet));

                if (rc == -EHOSTUNREACH) /* gateway is not on a local net */
                        return 0;       /* ignore the route entry */
                CERROR("Error %d creating route %s %d %s\n", rc,
                       libcfs_net2str(net), hops,
                       libcfs_nid2str(gateway));

                return rc;
        }

        LASSERT(!the_lnet.ln_shutdown);

        rnet2 = lnet_find_net_locked(net);
        if (rnet2 == NULL) {
                /* new network */
                list_add_tail(&rnet->lrn_list, lnet_net2rnethash(net));
                rnet2 = rnet;
        }

        /* Search for a duplicate route (it's a NOOP if it is) */
        add_route = 1;
        list_for_each(e, &rnet2->lrn_routes) {
                lnet_route_t *route2 = list_entry(e, lnet_route_t, lr_list);

                if (route2->lr_gateway == route->lr_gateway) {
                        add_route = 0;
                        break;
                }

                /* our lookups must be true */
                LASSERT(route2->lr_gateway->lp_nid != gateway);
        }

        if (add_route) {
                lnet_peer_addref_locked(route->lr_gateway); /* +1 for notify */
                lnet_add_route_to_rnet(rnet2, route);

                ni = route->lr_gateway->lp_ni;
                lnet_net_unlock(LNET_LOCK_EX);

                /* XXX Assume alive */
                if (ni->ni_lnd->lnd_notify != NULL)
                        (ni->ni_lnd->lnd_notify)(ni, gateway, 1);

                lnet_net_lock(LNET_LOCK_EX);
        }

        /* -1 for notify or !add_route */
        lnet_peer_decref_locked(route->lr_gateway);
        lnet_net_unlock(LNET_LOCK_EX);

        if (!add_route)
                LIBCFS_FREE(route, sizeof(*route));

        if (rnet != rnet2)
                LIBCFS_FREE(rnet, sizeof(*rnet));

        return 0;
}

int
lnet_check_routes(void)
{
        lnet_remotenet_t *rnet;
        lnet_route_t *route;
        lnet_route_t *route2;
        struct list_head *e1;
        struct list_head *e2;
        int cpt;
        struct list_head *rn_list;
        int i;

        cpt = lnet_net_lock_current();

        for (i = 0; i < LNET_REMOTE_NETS_HASH_SIZE; i++) {
                rn_list = &the_lnet.ln_remote_nets_hash[i];
                list_for_each(e1, rn_list) {
                        rnet = list_entry(e1, lnet_remotenet_t, lrn_list);

                        route2 = NULL;
                        list_for_each(e2, &rnet->lrn_routes) {
                                lnet_nid_t nid1;
                                lnet_nid_t nid2;
                                int net;

                                route = list_entry(e2, lnet_route_t,
                                                       lr_list);

                                if (route2 == NULL) {
                                        route2 = route;
                                        continue;
                                }

                                if (route->lr_gateway->lp_ni ==
                                    route2->lr_gateway->lp_ni)
                                        continue;

                                nid1 = route->lr_gateway->lp_nid;
                                nid2 = route2->lr_gateway->lp_nid;
                                net = rnet->lrn_net;

                                lnet_net_unlock(cpt);

                                CERROR("Routes to %s via %s and %s not supported\n",
                                       libcfs_net2str(net),
                                       libcfs_nid2str(nid1),
                                       libcfs_nid2str(nid2));
                                return -EINVAL;
                        }
                }
        }

        lnet_net_unlock(cpt);
        return 0;
}

int
lnet_del_route(__u32 net, lnet_nid_t gw_nid)
{
        struct lnet_peer *gateway;
        lnet_remotenet_t *rnet;
        lnet_route_t *route;
        struct list_head *e1;
        struct list_head *e2;
        int rc = -ENOENT;
        struct list_head *rn_list;
        int idx = 0;

        CDEBUG(D_NET, "Del route: net %s : gw %s\n",
               libcfs_net2str(net), libcfs_nid2str(gw_nid));

        /* NB Caller may specify either all routes via the given gateway
         * or a specific route entry actual NIDs) */

        lnet_net_lock(LNET_LOCK_EX);
        if (net == LNET_NIDNET(LNET_NID_ANY))
                rn_list = &the_lnet.ln_remote_nets_hash[0];
        else
                rn_list = lnet_net2rnethash(net);

 again:
        list_for_each(e1, rn_list) {
                rnet = list_entry(e1, lnet_remotenet_t, lrn_list);

                if (!(net == LNET_NIDNET(LNET_NID_ANY) ||
                        net == rnet->lrn_net))
                        continue;

                list_for_each(e2, &rnet->lrn_routes) {
                        route = list_entry(e2, lnet_route_t, lr_list);

                        gateway = route->lr_gateway;
                        if (!(gw_nid == LNET_NID_ANY ||
                              gw_nid == gateway->lp_nid))
                                continue;

                        list_del(&route->lr_list);
                        list_del(&route->lr_gwlist);
                        the_lnet.ln_remote_nets_version++;

                        if (list_empty(&rnet->lrn_routes))
                                list_del(&rnet->lrn_list);
                        else
                                rnet = NULL;

                        lnet_rtr_decref_locked(gateway);
                        lnet_peer_decref_locked(gateway);

                        lnet_net_unlock(LNET_LOCK_EX);

                        LIBCFS_FREE(route, sizeof(*route));

                        if (rnet != NULL)
                                LIBCFS_FREE(rnet, sizeof(*rnet));

                        rc = 0;
                        lnet_net_lock(LNET_LOCK_EX);
                        goto again;
                }
        }

        if (net == LNET_NIDNET(LNET_NID_ANY) &&
            ++idx < LNET_REMOTE_NETS_HASH_SIZE) {
                rn_list = &the_lnet.ln_remote_nets_hash[idx];
                goto again;
        }
        lnet_net_unlock(LNET_LOCK_EX);

        return rc;
}

void
lnet_destroy_routes(void)
{
        lnet_del_route(LNET_NIDNET(LNET_NID_ANY), LNET_NID_ANY);
}

int
lnet_get_route(int idx, __u32 *net, __u32 *hops,
               lnet_nid_t *gateway, __u32 *alive, __u32 *priority)
{
        struct list_head *e1;
        struct list_head *e2;
        lnet_remotenet_t *rnet;
        lnet_route_t *route;
        int cpt;
        int i;
        struct list_head *rn_list;

        cpt = lnet_net_lock_current();

        for (i = 0; i < LNET_REMOTE_NETS_HASH_SIZE; i++) {
                rn_list = &the_lnet.ln_remote_nets_hash[i];
                list_for_each(e1, rn_list) {
                        rnet = list_entry(e1, lnet_remotenet_t, lrn_list);

                        list_for_each(e2, &rnet->lrn_routes) {
                                route = list_entry(e2, lnet_route_t,
                                                       lr_list);

                                if (idx-- == 0) {
                                        *net      = rnet->lrn_net;
                                        *hops     = route->lr_hops;
                                        *priority = route->lr_priority;
                                        *gateway  = route->lr_gateway->lp_nid;
                                        *alive    = route->lr_gateway->lp_alive;
                                        lnet_net_unlock(cpt);
                                        return 0;
                                }
                        }
                }
        }

        lnet_net_unlock(cpt);
        return -ENOENT;
}

void
lnet_swap_pinginfo(lnet_ping_info_t *info)
{
        int i;
        lnet_ni_status_t *stat;

        __swab32s(&info->pi_magic);
        __swab32s(&info->pi_features);
        __swab32s(&info->pi_pid);
        __swab32s(&info->pi_nnis);
        for (i = 0; i < info->pi_nnis && i < LNET_MAX_RTR_NIS; i++) {
                stat = &info->pi_ni[i];
                __swab64s(&stat->ns_nid);
                __swab32s(&stat->ns_status);
        }
}

/**
 * parse router-checker pinginfo, record number of down NIs for remote
 * networks on that router.
 */
static void
lnet_parse_rc_info(lnet_rc_data_t *rcd)
{
        lnet_ping_info_t *info = rcd->rcd_pinginfo;
        struct lnet_peer *gw = rcd->rcd_gateway;
        lnet_route_t *rtr;

        if (!gw->lp_alive)
                return;

        if (info->pi_magic == __swab32(LNET_PROTO_PING_MAGIC))
                lnet_swap_pinginfo(info);

        /* NB always racing with network! */
        if (info->pi_magic != LNET_PROTO_PING_MAGIC) {
                CDEBUG(D_NET, "%s: Unexpected magic %08x\n",
                       libcfs_nid2str(gw->lp_nid), info->pi_magic);
                gw->lp_ping_feats = LNET_PING_FEAT_INVAL;
                return;
        }

        gw->lp_ping_feats = info->pi_features;
        if ((gw->lp_ping_feats & LNET_PING_FEAT_MASK) == 0) {
                CDEBUG(D_NET, "%s: Unexpected features 0x%x\n",
                       libcfs_nid2str(gw->lp_nid), gw->lp_ping_feats);
                return; /* nothing I can understand */
        }

        if ((gw->lp_ping_feats & LNET_PING_FEAT_NI_STATUS) == 0)
                return; /* can't carry NI status info */

        list_for_each_entry(rtr, &gw->lp_routes, lr_gwlist) {
                int ptl_status = LNET_NI_STATUS_INVALID;
                int down = 0;
                int up = 0;
                int i;

                for (i = 0; i < info->pi_nnis && i < LNET_MAX_RTR_NIS; i++) {
                        lnet_ni_status_t *stat = &info->pi_ni[i];
                        lnet_nid_t nid = stat->ns_nid;

                        if (nid == LNET_NID_ANY) {
                                CDEBUG(D_NET, "%s: unexpected LNET_NID_ANY\n",
                                       libcfs_nid2str(gw->lp_nid));
                                gw->lp_ping_feats = LNET_PING_FEAT_INVAL;
                                return;
                        }

                        if (LNET_NETTYP(LNET_NIDNET(nid)) == LOLND)
                                continue;

                        if (stat->ns_status == LNET_NI_STATUS_DOWN) {
                                if (LNET_NETTYP(LNET_NIDNET(nid)) != PTLLND)
                                        down++;
                                else if (ptl_status != LNET_NI_STATUS_UP)
                                        ptl_status = LNET_NI_STATUS_DOWN;
                                continue;
                        }

                        if (stat->ns_status == LNET_NI_STATUS_UP) {
                                if (LNET_NIDNET(nid) == rtr->lr_net) {
                                        up = 1;
                                        break;
                                }
                                /* ptl NIs are considered down only when
                                 * they're all down */
                                if (LNET_NETTYP(LNET_NIDNET(nid)) == PTLLND)
                                        ptl_status = LNET_NI_STATUS_UP;
                                continue;
                        }

                        CDEBUG(D_NET, "%s: Unexpected status 0x%x\n",
                               libcfs_nid2str(gw->lp_nid), stat->ns_status);
                        gw->lp_ping_feats = LNET_PING_FEAT_INVAL;
                        return;
                }

                if (up) { /* ignore downed NIs if NI for dest network is up */
                        rtr->lr_downis = 0;
                        continue;
                }
                rtr->lr_downis = down + (ptl_status == LNET_NI_STATUS_DOWN);
        }
}

static void
lnet_router_checker_event(lnet_event_t *event)
{
        lnet_rc_data_t *rcd = event->md.user_ptr;
        struct lnet_peer *lp;

        LASSERT(rcd != NULL);

        if (event->unlinked) {
                LNetInvalidateHandle(&rcd->rcd_mdh);
                return;
        }

        LASSERT(event->type == LNET_EVENT_SEND ||
                event->type == LNET_EVENT_REPLY);

        lp = rcd->rcd_gateway;
        LASSERT(lp != NULL);

         /* NB: it's called with holding lnet_res_lock, we have a few
          * places need to hold both locks at the same time, please take
          * care of lock ordering */
        lnet_net_lock(lp->lp_cpt);
        if (!lnet_isrouter(lp) || lp->lp_rcd != rcd) {
                /* ignore if no longer a router or rcd is replaced */
                goto out;
        }

        if (event->type == LNET_EVENT_SEND) {
                lp->lp_ping_notsent = 0;
                if (event->status == 0)
                        goto out;
        }

        /* LNET_EVENT_REPLY */
        /* A successful REPLY means the router is up.  If _any_ comms
         * to the router fail I assume it's down (this will happen if
         * we ping alive routers to try to detect router death before
         * apps get burned). */

        lnet_notify_locked(lp, 1, (event->status == 0), cfs_time_current());
        /* The router checker will wake up very shortly and do the
         * actual notification.
         * XXX If 'lp' stops being a router before then, it will still
         * have the notification pending!!! */

        if (avoid_asym_router_failure && event->status == 0)
                lnet_parse_rc_info(rcd);

 out:
        lnet_net_unlock(lp->lp_cpt);
}

static void
lnet_wait_known_routerstate(void)
{
        lnet_peer_t *rtr;
        struct list_head *entry;
        int all_known;

        LASSERT(the_lnet.ln_rc_state == LNET_RC_STATE_RUNNING);

        for (;;) {
                int cpt = lnet_net_lock_current();

                all_known = 1;
                list_for_each(entry, &the_lnet.ln_routers) {
                        rtr = list_entry(entry, lnet_peer_t, lp_rtr_list);

                        if (rtr->lp_alive_count == 0) {
                                all_known = 0;
                                break;
                        }
                }

                lnet_net_unlock(cpt);

                if (all_known)
                        return;

                set_current_state(TASK_UNINTERRUPTIBLE);
                schedule_timeout(cfs_time_seconds(1));
        }
}

void
lnet_router_ni_update_locked(lnet_peer_t *gw, __u32 net)
{
        lnet_route_t *rte;

        if ((gw->lp_ping_feats & LNET_PING_FEAT_NI_STATUS) != 0) {
                list_for_each_entry(rte, &gw->lp_routes, lr_gwlist) {
                        if (rte->lr_net == net) {
                                rte->lr_downis = 0;
                                break;
                        }
                }
        }
}

static void
lnet_update_ni_status_locked(void)
{
        lnet_ni_t *ni;
        time64_t now;
        int timeout;

        LASSERT(the_lnet.ln_routing);

        timeout = router_ping_timeout +
                  max(live_router_check_interval, dead_router_check_interval);

        now = ktime_get_real_seconds();
        list_for_each_entry(ni, &the_lnet.ln_nis, ni_list) {
                if (ni->ni_lnd->lnd_type == LOLND)
                        continue;

                if (now < ni->ni_last_alive + timeout)
                        continue;

                lnet_ni_lock(ni);
                /* re-check with lock */
                if (now < ni->ni_last_alive + timeout) {
                        lnet_ni_unlock(ni);
                        continue;
                }

                LASSERT(ni->ni_status != NULL);

                if (ni->ni_status->ns_status != LNET_NI_STATUS_DOWN) {
                        CDEBUG(D_NET, "NI(%s:%d) status changed to down\n",
                               libcfs_nid2str(ni->ni_nid), timeout);
                        /* NB: so far, this is the only place to set
                         * NI status to "down" */
                        ni->ni_status->ns_status = LNET_NI_STATUS_DOWN;
                }
                lnet_ni_unlock(ni);
        }
}

static void
lnet_destroy_rc_data(lnet_rc_data_t *rcd)
{
        LASSERT(list_empty(&rcd->rcd_list));
        /* detached from network */
        LASSERT(LNetHandleIsInvalid(rcd->rcd_mdh));

        if (rcd->rcd_gateway != NULL) {
                int cpt = rcd->rcd_gateway->lp_cpt;

                lnet_net_lock(cpt);
                lnet_peer_decref_locked(rcd->rcd_gateway);
                lnet_net_unlock(cpt);
        }

        if (rcd->rcd_pinginfo != NULL)
                LIBCFS_FREE(rcd->rcd_pinginfo, LNET_PINGINFO_SIZE);

        LIBCFS_FREE(rcd, sizeof(*rcd));
}

static lnet_rc_data_t *
lnet_create_rc_data_locked(lnet_peer_t *gateway)
{
        lnet_rc_data_t *rcd = NULL;
        lnet_ping_info_t *pi;
        int rc;
        int i;

        lnet_net_unlock(gateway->lp_cpt);

        LIBCFS_ALLOC(rcd, sizeof(*rcd));
        if (rcd == NULL)
                goto out;

        LNetInvalidateHandle(&rcd->rcd_mdh);
        INIT_LIST_HEAD(&rcd->rcd_list);

        LIBCFS_ALLOC(pi, LNET_PINGINFO_SIZE);
        if (pi == NULL)
                goto out;

        for (i = 0; i < LNET_MAX_RTR_NIS; i++) {
                pi->pi_ni[i].ns_nid = LNET_NID_ANY;
                pi->pi_ni[i].ns_status = LNET_NI_STATUS_INVALID;
        }
        rcd->rcd_pinginfo = pi;

        LASSERT(!LNetHandleIsInvalid(the_lnet.ln_rc_eqh));
        rc = LNetMDBind((lnet_md_t){.start     = pi,
                                    .user_ptr  = rcd,
                                    .length    = LNET_PINGINFO_SIZE,
                                    .threshold = LNET_MD_THRESH_INF,
                                    .options   = LNET_MD_TRUNCATE,
                                    .eq_handle = the_lnet.ln_rc_eqh},
                        LNET_UNLINK,
                        &rcd->rcd_mdh);
        if (rc < 0) {
                CERROR("Can't bind MD: %d\n", rc);
                goto out;
        }
        LASSERT(rc == 0);

        lnet_net_lock(gateway->lp_cpt);
        /* router table changed or someone has created rcd for this gateway */
        if (!lnet_isrouter(gateway) || gateway->lp_rcd != NULL) {
                lnet_net_unlock(gateway->lp_cpt);
                goto out;
        }

        lnet_peer_addref_locked(gateway);
        rcd->rcd_gateway = gateway;
        gateway->lp_rcd = rcd;
        gateway->lp_ping_notsent = 0;

        return rcd;

 out:
        if (rcd != NULL) {
                if (!LNetHandleIsInvalid(rcd->rcd_mdh)) {
                        rc = LNetMDUnlink(rcd->rcd_mdh);
                        LASSERT(rc == 0);
                }
                lnet_destroy_rc_data(rcd);
        }

        lnet_net_lock(gateway->lp_cpt);
        return gateway->lp_rcd;
}

static int
lnet_router_check_interval(lnet_peer_t *rtr)
{
        int secs;

        secs = rtr->lp_alive ? live_router_check_interval :
                               dead_router_check_interval;
        if (secs < 0)
                secs = 0;

        return secs;
}

static void
lnet_ping_router_locked(lnet_peer_t *rtr)
{
        lnet_rc_data_t *rcd = NULL;
        unsigned long now = cfs_time_current();
        int secs;

        lnet_peer_addref_locked(rtr);

        if (rtr->lp_ping_deadline != 0 && /* ping timed out? */
            cfs_time_after(now, rtr->lp_ping_deadline))
                lnet_notify_locked(rtr, 1, 0, now);

        /* Run any outstanding notifications */
        lnet_ni_notify_locked(rtr->lp_ni, rtr);

        if (!lnet_isrouter(rtr) ||
            the_lnet.ln_rc_state != LNET_RC_STATE_RUNNING) {
                /* router table changed or router checker is shutting down */
                lnet_peer_decref_locked(rtr);
                return;
        }

        rcd = rtr->lp_rcd != NULL ?
              rtr->lp_rcd : lnet_create_rc_data_locked(rtr);

        if (rcd == NULL)
                return;

        secs = lnet_router_check_interval(rtr);

        CDEBUG(D_NET,
               "rtr %s %d: deadline %lu ping_notsent %d alive %d alive_count %d lp_ping_timestamp %lu\n",
               libcfs_nid2str(rtr->lp_nid), secs,
               rtr->lp_ping_deadline, rtr->lp_ping_notsent,
               rtr->lp_alive, rtr->lp_alive_count, rtr->lp_ping_timestamp);

        if (secs != 0 && !rtr->lp_ping_notsent &&
            cfs_time_after(now, cfs_time_add(rtr->lp_ping_timestamp,
                                             cfs_time_seconds(secs)))) {
                int rc;
                lnet_process_id_t id;
                lnet_handle_md_t mdh;

                id.nid = rtr->lp_nid;
                id.pid = LUSTRE_SRV_LNET_PID;
                CDEBUG(D_NET, "Check: %s\n", libcfs_id2str(id));

                rtr->lp_ping_notsent   = 1;
                rtr->lp_ping_timestamp = now;

                mdh = rcd->rcd_mdh;

                if (rtr->lp_ping_deadline == 0) {
                        rtr->lp_ping_deadline =
                                cfs_time_shift(router_ping_timeout);
                }

                lnet_net_unlock(rtr->lp_cpt);

                rc = LNetGet(LNET_NID_ANY, mdh, id, LNET_RESERVED_PORTAL,
                             LNET_PROTO_PING_MATCHBITS, 0);

                lnet_net_lock(rtr->lp_cpt);
                if (rc != 0)
                        rtr->lp_ping_notsent = 0; /* no event pending */
        }

        lnet_peer_decref_locked(rtr);
}

int
lnet_router_checker_start(void)
{
        int rc;
        int eqsz;

        LASSERT(the_lnet.ln_rc_state == LNET_RC_STATE_SHUTDOWN);

        if (check_routers_before_use &&
            dead_router_check_interval <= 0) {
                LCONSOLE_ERROR_MSG(0x10a, "'dead_router_check_interval' must be set if 'check_routers_before_use' is set\n");
                return -EINVAL;
        }

        if (!the_lnet.ln_routing &&
            live_router_check_interval <= 0 &&
            dead_router_check_interval <= 0)
                return 0;

        sema_init(&the_lnet.ln_rc_signal, 0);
        /* EQ size doesn't matter; the callback is guaranteed to get every
         * event */
        eqsz = 0;
        rc = LNetEQAlloc(eqsz, lnet_router_checker_event,
                         &the_lnet.ln_rc_eqh);
        if (rc != 0) {
                CERROR("Can't allocate EQ(%d): %d\n", eqsz, rc);
                return -ENOMEM;
        }

        the_lnet.ln_rc_state = LNET_RC_STATE_RUNNING;
        rc = PTR_ERR(kthread_run(lnet_router_checker,
                                 NULL, "router_checker"));
        if (IS_ERR_VALUE(rc)) {
                CERROR("Can't start router checker thread: %d\n", rc);
                /* block until event callback signals exit */
                down(&the_lnet.ln_rc_signal);
                rc = LNetEQFree(the_lnet.ln_rc_eqh);
                LASSERT(rc == 0);
                the_lnet.ln_rc_state = LNET_RC_STATE_SHUTDOWN;
                return -ENOMEM;
        }

        if (check_routers_before_use) {
                /* Note that a helpful side-effect of pinging all known routers
                 * at startup is that it makes them drop stale connections they
                 * may have to a previous instance of me. */
                lnet_wait_known_routerstate();
        }

        return 0;
}

void
lnet_router_checker_stop(void)
{
        int rc;

        if (the_lnet.ln_rc_state == LNET_RC_STATE_SHUTDOWN)
                return;

        LASSERT(the_lnet.ln_rc_state == LNET_RC_STATE_RUNNING);
        the_lnet.ln_rc_state = LNET_RC_STATE_STOPPING;

        /* block until event callback signals exit */
        down(&the_lnet.ln_rc_signal);
        LASSERT(the_lnet.ln_rc_state == LNET_RC_STATE_SHUTDOWN);

        rc = LNetEQFree(the_lnet.ln_rc_eqh);
        LASSERT(rc == 0);
}

static void
lnet_prune_rc_data(int wait_unlink)
{
        lnet_rc_data_t *rcd;
        lnet_rc_data_t *tmp;
        lnet_peer_t *lp;
        struct list_head head;
        int i = 2;

        if (likely(the_lnet.ln_rc_state == LNET_RC_STATE_RUNNING &&
                   list_empty(&the_lnet.ln_rcd_deathrow) &&
                   list_empty(&the_lnet.ln_rcd_zombie)))
                return;

        INIT_LIST_HEAD(&head);

        lnet_net_lock(LNET_LOCK_EX);

        if (the_lnet.ln_rc_state != LNET_RC_STATE_RUNNING) {
                /* router checker is stopping, prune all */
                list_for_each_entry(lp, &the_lnet.ln_routers,
                                        lp_rtr_list) {
                        if (lp->lp_rcd == NULL)
                                continue;

                        LASSERT(list_empty(&lp->lp_rcd->rcd_list));
                        list_add(&lp->lp_rcd->rcd_list,
                                     &the_lnet.ln_rcd_deathrow);
                        lp->lp_rcd = NULL;
                }
        }

        /* unlink all RCDs on deathrow list */
        list_splice_init(&the_lnet.ln_rcd_deathrow, &head);

        if (!list_empty(&head)) {
                lnet_net_unlock(LNET_LOCK_EX);

                list_for_each_entry(rcd, &head, rcd_list)
                        LNetMDUnlink(rcd->rcd_mdh);

                lnet_net_lock(LNET_LOCK_EX);
        }

        list_splice_init(&head, &the_lnet.ln_rcd_zombie);

        /* release all zombie RCDs */
        while (!list_empty(&the_lnet.ln_rcd_zombie)) {
                list_for_each_entry_safe(rcd, tmp, &the_lnet.ln_rcd_zombie,
                                             rcd_list) {
                        if (LNetHandleIsInvalid(rcd->rcd_mdh))
                                list_move(&rcd->rcd_list, &head);
                }

                wait_unlink = wait_unlink &&
                              !list_empty(&the_lnet.ln_rcd_zombie);

                lnet_net_unlock(LNET_LOCK_EX);

                while (!list_empty(&head)) {
                        rcd = list_entry(head.next,
                                             lnet_rc_data_t, rcd_list);
                        list_del_init(&rcd->rcd_list);
                        lnet_destroy_rc_data(rcd);
                }

                if (!wait_unlink)
                        return;

                i++;
                CDEBUG(((i & (-i)) == i) ? D_WARNING : D_NET,
                       "Waiting for rc buffers to unlink\n");
                set_current_state(TASK_UNINTERRUPTIBLE);
                schedule_timeout(cfs_time_seconds(1) / 4);

                lnet_net_lock(LNET_LOCK_EX);
        }

        lnet_net_unlock(LNET_LOCK_EX);
}

static int
lnet_router_checker(void *arg)
{
        lnet_peer_t *rtr;
        struct list_head *entry;

        cfs_block_allsigs();

        LASSERT(the_lnet.ln_rc_state == LNET_RC_STATE_RUNNING);

        while (the_lnet.ln_rc_state == LNET_RC_STATE_RUNNING) {
                __u64 version;
                int cpt;
                int cpt2;

                cpt = lnet_net_lock_current();
rescan:
                version = the_lnet.ln_routers_version;

                list_for_each(entry, &the_lnet.ln_routers) {
                        rtr = list_entry(entry, lnet_peer_t, lp_rtr_list);

                        cpt2 = lnet_cpt_of_nid_locked(rtr->lp_nid);
                        if (cpt != cpt2) {
                                lnet_net_unlock(cpt);
                                cpt = cpt2;
                                lnet_net_lock(cpt);
                                /* the routers list has changed */
                                if (version != the_lnet.ln_routers_version)
                                        goto rescan;
                        }

                        lnet_ping_router_locked(rtr);

                        /* NB dropped lock */
                        if (version != the_lnet.ln_routers_version) {
                                /* the routers list has changed */
                                goto rescan;
                        }
                }

                if (the_lnet.ln_routing)
                        lnet_update_ni_status_locked();

                lnet_net_unlock(cpt);

                lnet_prune_rc_data(0); /* don't wait for UNLINK */

                /* Call schedule_timeout() here always adds 1 to load average
                 * because kernel counts # active tasks as nr_running
                 * + nr_uninterruptible. */
                set_current_state(TASK_INTERRUPTIBLE);
                schedule_timeout(cfs_time_seconds(1));
        }

        LASSERT(the_lnet.ln_rc_state == LNET_RC_STATE_STOPPING);

        lnet_prune_rc_data(1); /* wait for UNLINK */

        the_lnet.ln_rc_state = LNET_RC_STATE_SHUTDOWN;
        up(&the_lnet.ln_rc_signal);
        /* The unlink event callback will signal final completion */
        return 0;
}

static void
lnet_destroy_rtrbuf(lnet_rtrbuf_t *rb, int npages)
{
        int sz = offsetof(lnet_rtrbuf_t, rb_kiov[npages]);

        while (--npages >= 0)
                __free_page(rb->rb_kiov[npages].kiov_page);

        LIBCFS_FREE(rb, sz);
}

static lnet_rtrbuf_t *
lnet_new_rtrbuf(lnet_rtrbufpool_t *rbp, int cpt)
{
        int npages = rbp->rbp_npages;
        int sz = offsetof(lnet_rtrbuf_t, rb_kiov[npages]);
        struct page *page;
        lnet_rtrbuf_t *rb;
        int i;

        LIBCFS_CPT_ALLOC(rb, lnet_cpt_table(), cpt, sz);
        if (rb == NULL)
                return NULL;

        rb->rb_pool = rbp;

        for (i = 0; i < npages; i++) {
                page = alloc_pages_node(
                                cfs_cpt_spread_node(lnet_cpt_table(), cpt),
                                GFP_KERNEL | __GFP_ZERO, 0);
                if (page == NULL) {
                        while (--i >= 0)
                                __free_page(rb->rb_kiov[i].kiov_page);

                        LIBCFS_FREE(rb, sz);
                        return NULL;
                }

                rb->rb_kiov[i].kiov_len = PAGE_CACHE_SIZE;
                rb->rb_kiov[i].kiov_offset = 0;
                rb->rb_kiov[i].kiov_page = page;
        }

        return rb;
}

static void
lnet_rtrpool_free_bufs(lnet_rtrbufpool_t *rbp)
{
        int npages = rbp->rbp_npages;
        int nbuffers = 0;
        lnet_rtrbuf_t *rb;

        if (rbp->rbp_nbuffers == 0) /* not initialized or already freed */
                return;

        LASSERT(list_empty(&rbp->rbp_msgs));
        LASSERT(rbp->rbp_credits == rbp->rbp_nbuffers);

        while (!list_empty(&rbp->rbp_bufs)) {
                LASSERT(rbp->rbp_credits > 0);

                rb = list_entry(rbp->rbp_bufs.next,
                                    lnet_rtrbuf_t, rb_list);
                list_del(&rb->rb_list);
                lnet_destroy_rtrbuf(rb, npages);
                nbuffers++;
        }

        LASSERT(rbp->rbp_nbuffers == nbuffers);
        LASSERT(rbp->rbp_credits == nbuffers);

        rbp->rbp_nbuffers = rbp->rbp_credits = 0;
}

static int
lnet_rtrpool_alloc_bufs(lnet_rtrbufpool_t *rbp, int nbufs, int cpt)
{
        lnet_rtrbuf_t *rb;
        int i;

        if (rbp->rbp_nbuffers != 0) {
                LASSERT(rbp->rbp_nbuffers == nbufs);
                return 0;
        }

        for (i = 0; i < nbufs; i++) {
                rb = lnet_new_rtrbuf(rbp, cpt);

                if (rb == NULL) {
                        CERROR("Failed to allocate %d router bufs of %d pages\n",
                               nbufs, rbp->rbp_npages);
                        return -ENOMEM;
                }

                rbp->rbp_nbuffers++;
                rbp->rbp_credits++;
                rbp->rbp_mincredits++;
                list_add(&rb->rb_list, &rbp->rbp_bufs);

                /* No allocation "under fire" */
                /* Otherwise we'd need code to schedule blocked msgs etc */
                LASSERT(!the_lnet.ln_routing);
        }

        LASSERT(rbp->rbp_credits == nbufs);
        return 0;
}

static void
lnet_rtrpool_init(lnet_rtrbufpool_t *rbp, int npages)
{
        INIT_LIST_HEAD(&rbp->rbp_msgs);
        INIT_LIST_HEAD(&rbp->rbp_bufs);

        rbp->rbp_npages = npages;
        rbp->rbp_credits = 0;
        rbp->rbp_mincredits = 0;
}

void
lnet_rtrpools_free(void)
{
        lnet_rtrbufpool_t *rtrp;
        int i;

        if (the_lnet.ln_rtrpools == NULL) /* uninitialized or freed */
                return;

        cfs_percpt_for_each(rtrp, i, the_lnet.ln_rtrpools) {
                lnet_rtrpool_free_bufs(&rtrp[0]);
                lnet_rtrpool_free_bufs(&rtrp[1]);
                lnet_rtrpool_free_bufs(&rtrp[2]);
        }

        cfs_percpt_free(the_lnet.ln_rtrpools);
        the_lnet.ln_rtrpools = NULL;
}

static int
lnet_nrb_tiny_calculate(int npages)
{
        int nrbs = LNET_NRB_TINY;

        if (tiny_router_buffers < 0) {
                LCONSOLE_ERROR_MSG(0x10c,
                                   "tiny_router_buffers=%d invalid when routing enabled\n",
                                   tiny_router_buffers);
                return -1;
        }

        if (tiny_router_buffers > 0)
                nrbs = tiny_router_buffers;

        nrbs /= LNET_CPT_NUMBER;
        return max(nrbs, LNET_NRB_TINY_MIN);
}

static int
lnet_nrb_small_calculate(int npages)
{
        int nrbs = LNET_NRB_SMALL;

        if (small_router_buffers < 0) {
                LCONSOLE_ERROR_MSG(0x10c,
                                   "small_router_buffers=%d invalid when routing enabled\n",
                                   small_router_buffers);
                return -1;
        }

        if (small_router_buffers > 0)
                nrbs = small_router_buffers;

        nrbs /= LNET_CPT_NUMBER;
        return max(nrbs, LNET_NRB_SMALL_MIN);
}

static int
lnet_nrb_large_calculate(int npages)
{
        int nrbs = LNET_NRB_LARGE;

        if (large_router_buffers < 0) {
                LCONSOLE_ERROR_MSG(0x10c,
                                   "large_router_buffers=%d invalid when routing enabled\n",
                                   large_router_buffers);
                return -1;
        }

        if (large_router_buffers > 0)
                nrbs = large_router_buffers;

        nrbs /= LNET_CPT_NUMBER;
        return max(nrbs, LNET_NRB_LARGE_MIN);
}

int
lnet_rtrpools_alloc(int im_a_router)
{
        lnet_rtrbufpool_t *rtrp;
        int large_pages;
        int small_pages = 1;
        int nrb_tiny;
        int nrb_small;
        int nrb_large;
        int rc;
        int i;

        large_pages = (LNET_MTU + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

        if (!strcmp(forwarding, "")) {
                /* not set either way */
                if (!im_a_router)
                        return 0;
        } else if (!strcmp(forwarding, "disabled")) {
                /* explicitly disabled */
                return 0;
        } else if (!strcmp(forwarding, "enabled")) {
                /* explicitly enabled */
        } else {
                LCONSOLE_ERROR_MSG(0x10b, "'forwarding' not set to either 'enabled' or 'disabled'\n");
                return -EINVAL;
        }

        nrb_tiny = lnet_nrb_tiny_calculate(0);
        if (nrb_tiny < 0)
                return -EINVAL;

        nrb_small = lnet_nrb_small_calculate(small_pages);
        if (nrb_small < 0)
                return -EINVAL;

        nrb_large = lnet_nrb_large_calculate(large_pages);
        if (nrb_large < 0)
                return -EINVAL;

        the_lnet.ln_rtrpools = cfs_percpt_alloc(lnet_cpt_table(),
                                                LNET_NRBPOOLS *
                                                sizeof(lnet_rtrbufpool_t));
        if (the_lnet.ln_rtrpools == NULL) {
                LCONSOLE_ERROR_MSG(0x10c,
                                   "Failed to initialize router buffe pool\n");
                return -ENOMEM;
        }

        cfs_percpt_for_each(rtrp, i, the_lnet.ln_rtrpools) {
                lnet_rtrpool_init(&rtrp[0], 0);
                rc = lnet_rtrpool_alloc_bufs(&rtrp[0], nrb_tiny, i);
                if (rc != 0)
                        goto failed;

                lnet_rtrpool_init(&rtrp[1], small_pages);
                rc = lnet_rtrpool_alloc_bufs(&rtrp[1], nrb_small, i);
                if (rc != 0)
                        goto failed;

                lnet_rtrpool_init(&rtrp[2], large_pages);
                rc = lnet_rtrpool_alloc_bufs(&rtrp[2], nrb_large, i);
                if (rc != 0)
                        goto failed;
        }

        lnet_net_lock(LNET_LOCK_EX);
        the_lnet.ln_routing = 1;
        lnet_net_unlock(LNET_LOCK_EX);

        return 0;

 failed:
        lnet_rtrpools_free();
        return rc;
}

int
lnet_notify(lnet_ni_t *ni, lnet_nid_t nid, int alive, unsigned long when)
{
        struct lnet_peer *lp = NULL;
        unsigned long now = cfs_time_current();
        int cpt = lnet_cpt_of_nid(nid);

        LASSERT(!in_interrupt());

        CDEBUG(D_NET, "%s notifying %s: %s\n",
                (ni == NULL) ? "userspace" : libcfs_nid2str(ni->ni_nid),
                libcfs_nid2str(nid),
                alive ? "up" : "down");

        if (ni != NULL &&
            LNET_NIDNET(ni->ni_nid) != LNET_NIDNET(nid)) {
                CWARN("Ignoring notification of %s %s by %s (different net)\n",
                        libcfs_nid2str(nid), alive ? "birth" : "death",
                        libcfs_nid2str(ni->ni_nid));
                return -EINVAL;
        }

        /* can't do predictions... */
        if (cfs_time_after(when, now)) {
                CWARN("Ignoring prediction from %s of %s %s %ld seconds in the future\n",
                      (ni == NULL) ? "userspace" : libcfs_nid2str(ni->ni_nid),
                      libcfs_nid2str(nid), alive ? "up" : "down",
                      cfs_duration_sec(cfs_time_sub(when, now)));
                return -EINVAL;
        }

        if (ni != NULL && !alive &&          /* LND telling me she's down */
            !auto_down) {                      /* auto-down disabled */
                CDEBUG(D_NET, "Auto-down disabled\n");
                return 0;
        }

        lnet_net_lock(cpt);

        if (the_lnet.ln_shutdown) {
                lnet_net_unlock(cpt);
                return -ESHUTDOWN;
        }

        lp = lnet_find_peer_locked(the_lnet.ln_peer_tables[cpt], nid);
        if (lp == NULL) {
                /* nid not found */
                lnet_net_unlock(cpt);
                CDEBUG(D_NET, "%s not found\n", libcfs_nid2str(nid));
                return 0;
        }

        /* We can't fully trust LND on reporting exact peer last_alive
         * if he notifies us about dead peer. For example ksocklnd can
         * call us with when == _time_when_the_node_was_booted_ if
         * no connections were successfully established */
        if (ni != NULL && !alive && when < lp->lp_last_alive)
                when = lp->lp_last_alive;

        lnet_notify_locked(lp, ni == NULL, alive, when);

        lnet_ni_notify_locked(ni, lp);

        lnet_peer_decref_locked(lp);

        lnet_net_unlock(cpt);
        return 0;
}
EXPORT_SYMBOL(lnet_notify);