/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program 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 version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lnet/lnet/peer.c
 */

#define DEBUG_SUBSYSTEM S_LNET

#include "../../include/linux/lnet/lib-lnet.h"
#include "../../include/linux/lnet/lib-dlc.h"

int
lnet_peer_tables_create(void)
{
        struct lnet_peer_table *ptable;
        struct list_head *hash;
        int i;
        int j;

        the_lnet.ln_peer_tables = cfs_percpt_alloc(lnet_cpt_table(),
                                                   sizeof(*ptable));
        if (!the_lnet.ln_peer_tables) {
                CERROR("Failed to allocate cpu-partition peer tables\n");
                return -ENOMEM;
        }

        cfs_percpt_for_each(ptable, i, the_lnet.ln_peer_tables) {
                INIT_LIST_HEAD(&ptable->pt_deathrow);

                LIBCFS_CPT_ALLOC(hash, lnet_cpt_table(), i,
                                 LNET_PEER_HASH_SIZE * sizeof(*hash));
                if (!hash) {
                        CERROR("Failed to create peer hash table\n");
                        lnet_peer_tables_destroy();
                        return -ENOMEM;
                }

                for (j = 0; j < LNET_PEER_HASH_SIZE; j++)
                        INIT_LIST_HEAD(&hash[j]);
                ptable->pt_hash = hash; /* sign of initialization */
        }

        return 0;
}

void
lnet_peer_tables_destroy(void)
{
        struct lnet_peer_table *ptable;
        struct list_head *hash;
        int i;
        int j;

        if (!the_lnet.ln_peer_tables)
                return;

        cfs_percpt_for_each(ptable, i, the_lnet.ln_peer_tables) {
                hash = ptable->pt_hash;
                if (!hash) /* not initialized */
                        break;

                LASSERT(list_empty(&ptable->pt_deathrow));

                ptable->pt_hash = NULL;
                for (j = 0; j < LNET_PEER_HASH_SIZE; j++)
                        LASSERT(list_empty(&hash[j]));

                LIBCFS_FREE(hash, LNET_PEER_HASH_SIZE * sizeof(*hash));
        }

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

static void
lnet_peer_table_cleanup_locked(struct lnet_ni *ni,
                               struct lnet_peer_table *ptable)
{
        int i;
        struct lnet_peer *lp;
        struct lnet_peer *tmp;

        for (i = 0; i < LNET_PEER_HASH_SIZE; i++) {
                list_for_each_entry_safe(lp, tmp, &ptable->pt_hash[i],
                                         lp_hashlist) {
                        if (ni && ni != lp->lp_ni)
                                continue;
                        list_del_init(&lp->lp_hashlist);
                        /* Lose hash table's ref */
                        ptable->pt_zombies++;
                        lnet_peer_decref_locked(lp);
                }
        }
}

static void
lnet_peer_table_deathrow_wait_locked(struct lnet_peer_table *ptable,
                                     int cpt_locked)
{
        int i;

        for (i = 3; ptable->pt_zombies; i++) {
                lnet_net_unlock(cpt_locked);

                if (is_power_of_2(i)) {
                        CDEBUG(D_WARNING,
                               "Waiting for %d zombies on peer table\n",
                               ptable->pt_zombies);
                }
                set_current_state(TASK_UNINTERRUPTIBLE);
                schedule_timeout(cfs_time_seconds(1) >> 1);
                lnet_net_lock(cpt_locked);
        }
}

static void
lnet_peer_table_del_rtrs_locked(struct lnet_ni *ni,
                                struct lnet_peer_table *ptable,
                                int cpt_locked)
{
        struct lnet_peer *lp;
        struct lnet_peer *tmp;
        lnet_nid_t lp_nid;
        int i;

        for (i = 0; i < LNET_PEER_HASH_SIZE; i++) {
                list_for_each_entry_safe(lp, tmp, &ptable->pt_hash[i],
                                         lp_hashlist) {
                        if (ni != lp->lp_ni)
                                continue;

                        if (!lp->lp_rtr_refcount)
                                continue;

                        lp_nid = lp->lp_nid;

                        lnet_net_unlock(cpt_locked);
                        lnet_del_route(LNET_NIDNET(LNET_NID_ANY), lp_nid);
                        lnet_net_lock(cpt_locked);
                }
        }
}

void
lnet_peer_tables_cleanup(struct lnet_ni *ni)
{
        struct lnet_peer_table *ptable;
        struct list_head deathrow;
        struct lnet_peer *lp;
        struct lnet_peer *temp;
        int i;

        INIT_LIST_HEAD(&deathrow);

        LASSERT(the_lnet.ln_shutdown || ni);
        /*
         * If just deleting the peers for a NI, get rid of any routes these
         * peers are gateways for.
         */
        cfs_percpt_for_each(ptable, i, the_lnet.ln_peer_tables) {
                lnet_net_lock(i);
                lnet_peer_table_del_rtrs_locked(ni, ptable, i);
                lnet_net_unlock(i);
        }

        /*
         * Start the process of moving the applicable peers to
         * deathrow.
         */
        cfs_percpt_for_each(ptable, i, the_lnet.ln_peer_tables) {
                lnet_net_lock(i);
                lnet_peer_table_cleanup_locked(ni, ptable);
                lnet_net_unlock(i);
        }

        /* Cleanup all entries on deathrow. */
        cfs_percpt_for_each(ptable, i, the_lnet.ln_peer_tables) {
                lnet_net_lock(i);
                lnet_peer_table_deathrow_wait_locked(ptable, i);
                list_splice_init(&ptable->pt_deathrow, &deathrow);
                lnet_net_unlock(i);
        }

        list_for_each_entry_safe(lp, temp, &deathrow, lp_hashlist) {
                list_del(&lp->lp_hashlist);
                LIBCFS_FREE(lp, sizeof(*lp));
        }
}

void
lnet_destroy_peer_locked(struct lnet_peer *lp)
{
        struct lnet_peer_table *ptable;

        LASSERT(!lp->lp_refcount);
        LASSERT(!lp->lp_rtr_refcount);
        LASSERT(list_empty(&lp->lp_txq));
        LASSERT(list_empty(&lp->lp_hashlist));
        LASSERT(!lp->lp_txqnob);

        ptable = the_lnet.ln_peer_tables[lp->lp_cpt];
        LASSERT(ptable->pt_number > 0);
        ptable->pt_number--;

        lnet_ni_decref_locked(lp->lp_ni, lp->lp_cpt);
        lp->lp_ni = NULL;

        list_add(&lp->lp_hashlist, &ptable->pt_deathrow);
        LASSERT(ptable->pt_zombies > 0);
        ptable->pt_zombies--;
}

struct lnet_peer *
lnet_find_peer_locked(struct lnet_peer_table *ptable, lnet_nid_t nid)
{
        struct list_head *peers;
        struct lnet_peer *lp;

        LASSERT(!the_lnet.ln_shutdown);

        peers = &ptable->pt_hash[lnet_nid2peerhash(nid)];
        list_for_each_entry(lp, peers, lp_hashlist) {
                if (lp->lp_nid == nid) {
                        lnet_peer_addref_locked(lp);
                        return lp;
                }
        }

        return NULL;
}

int
lnet_nid2peer_locked(struct lnet_peer **lpp, lnet_nid_t nid, int cpt)
{
        struct lnet_peer_table *ptable;
        struct lnet_peer *lp = NULL;
        struct lnet_peer *lp2;
        int cpt2;
        int rc = 0;

        *lpp = NULL;
        if (the_lnet.ln_shutdown) /* it's shutting down */
                return -ESHUTDOWN;

        /* cpt can be LNET_LOCK_EX if it's called from router functions */
        cpt2 = cpt != LNET_LOCK_EX ? cpt : lnet_cpt_of_nid_locked(nid);

        ptable = the_lnet.ln_peer_tables[cpt2];
        lp = lnet_find_peer_locked(ptable, nid);
        if (lp) {
                *lpp = lp;
                return 0;
        }

        if (!list_empty(&ptable->pt_deathrow)) {
                lp = list_entry(ptable->pt_deathrow.next,
                                struct lnet_peer, lp_hashlist);
                list_del(&lp->lp_hashlist);
        }

        /*
         * take extra refcount in case another thread has shutdown LNet
         * and destroyed locks and peer-table before I finish the allocation
         */
        ptable->pt_number++;
        lnet_net_unlock(cpt);

        if (lp)
                memset(lp, 0, sizeof(*lp));
        else
                LIBCFS_CPT_ALLOC(lp, lnet_cpt_table(), cpt2, sizeof(*lp));

        if (!lp) {
                rc = -ENOMEM;
                lnet_net_lock(cpt);
                goto out;
        }

        INIT_LIST_HEAD(&lp->lp_txq);
        INIT_LIST_HEAD(&lp->lp_rtrq);
        INIT_LIST_HEAD(&lp->lp_routes);

        lp->lp_notify = 0;
        lp->lp_notifylnd = 0;
        lp->lp_notifying = 0;
        lp->lp_alive_count = 0;
        lp->lp_timestamp = 0;
        lp->lp_alive = !lnet_peers_start_down(); /* 1 bit!! */
        lp->lp_last_alive = cfs_time_current(); /* assumes alive */
        lp->lp_last_query = 0; /* haven't asked NI yet */
        lp->lp_ping_timestamp = 0;
        lp->lp_ping_feats = LNET_PING_FEAT_INVAL;
        lp->lp_nid = nid;
        lp->lp_cpt = cpt2;
        lp->lp_refcount = 2;    /* 1 for caller; 1 for hash */
        lp->lp_rtr_refcount = 0;

        lnet_net_lock(cpt);

        if (the_lnet.ln_shutdown) {
                rc = -ESHUTDOWN;
                goto out;
        }

        lp2 = lnet_find_peer_locked(ptable, nid);
        if (lp2) {
                *lpp = lp2;
                goto out;
        }

        lp->lp_ni = lnet_net2ni_locked(LNET_NIDNET(nid), cpt2);
        if (!lp->lp_ni) {
                rc = -EHOSTUNREACH;
                goto out;
        }

        lp->lp_txcredits = lp->lp_ni->ni_peertxcredits;
        lp->lp_mintxcredits = lp->lp_ni->ni_peertxcredits;
        lp->lp_rtrcredits = lnet_peer_buffer_credits(lp->lp_ni);
        lp->lp_minrtrcredits = lnet_peer_buffer_credits(lp->lp_ni);

        list_add_tail(&lp->lp_hashlist,
                      &ptable->pt_hash[lnet_nid2peerhash(nid)]);
        ptable->pt_version++;
        *lpp = lp;

        return 0;
out:
        if (lp)
                list_add(&lp->lp_hashlist, &ptable->pt_deathrow);
        ptable->pt_number--;
        return rc;
}

void
lnet_debug_peer(lnet_nid_t nid)
{
        char *aliveness = "NA";
        struct lnet_peer *lp;
        int rc;
        int cpt;

        cpt = lnet_cpt_of_nid(nid);
        lnet_net_lock(cpt);

        rc = lnet_nid2peer_locked(&lp, nid, cpt);
        if (rc) {
                lnet_net_unlock(cpt);
                CDEBUG(D_WARNING, "No peer %s\n", libcfs_nid2str(nid));
                return;
        }

        if (lnet_isrouter(lp) || lnet_peer_aliveness_enabled(lp))
                aliveness = lp->lp_alive ? "up" : "down";

        CDEBUG(D_WARNING, "%-24s %4d %5s %5d %5d %5d %5d %5d %ld\n",
               libcfs_nid2str(lp->lp_nid), lp->lp_refcount,
               aliveness, lp->lp_ni->ni_peertxcredits,
               lp->lp_rtrcredits, lp->lp_minrtrcredits,
               lp->lp_txcredits, lp->lp_mintxcredits, lp->lp_txqnob);

        lnet_peer_decref_locked(lp);

        lnet_net_unlock(cpt);
}

int
lnet_get_peer_info(__u32 peer_index, __u64 *nid,
                   char aliveness[LNET_MAX_STR_LEN],
                   __u32 *cpt_iter, __u32 *refcount,
                   __u32 *ni_peer_tx_credits, __u32 *peer_tx_credits,
                   __u32 *peer_rtr_credits, __u32 *peer_min_rtr_credits,
                   __u32 *peer_tx_qnob)
{
        struct lnet_peer_table *peer_table;
        struct lnet_peer *lp;
        bool found = false;
        int lncpt, j;

        /* get the number of CPTs */
        lncpt = cfs_percpt_number(the_lnet.ln_peer_tables);

        /*
         * if the cpt number to be examined is >= the number of cpts in
         * the system then indicate that there are no more cpts to examin
         */
        if (*cpt_iter >= lncpt)
                return -ENOENT;

        /* get the current table */
        peer_table = the_lnet.ln_peer_tables[*cpt_iter];
        /* if the ptable is NULL then there are no more cpts to examine */
        if (!peer_table)
                return -ENOENT;

        lnet_net_lock(*cpt_iter);

        for (j = 0; j < LNET_PEER_HASH_SIZE && !found; j++) {
                struct list_head *peers = &peer_table->pt_hash[j];

                list_for_each_entry(lp, peers, lp_hashlist) {
                        if (peer_index-- > 0)
                                continue;

                        snprintf(aliveness, LNET_MAX_STR_LEN, "NA");
                        if (lnet_isrouter(lp) ||
                            lnet_peer_aliveness_enabled(lp))
                                snprintf(aliveness, LNET_MAX_STR_LEN,
                                         lp->lp_alive ? "up" : "down");

                        *nid = lp->lp_nid;
                        *refcount = lp->lp_refcount;
                        *ni_peer_tx_credits = lp->lp_ni->ni_peertxcredits;
                        *peer_tx_credits = lp->lp_txcredits;
                        *peer_rtr_credits = lp->lp_rtrcredits;
                        *peer_min_rtr_credits = lp->lp_mintxcredits;
                        *peer_tx_qnob = lp->lp_txqnob;

                        found = true;
                }
        }
        lnet_net_unlock(*cpt_iter);

        *cpt_iter = lncpt;

        return found ? 0 : -ENOENT;
}