/*
 * net/tipc/name_table.c: TIPC name table code
 *
 * Copyright (c) 2000-2006, 2014-2015, Ericsson AB
 * Copyright (c) 2004-2008, 2010-2014, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <net/sock.h>
#include "core.h"
#include "netlink.h"
#include "name_table.h"
#include "name_distr.h"
#include "subscr.h"
#include "bcast.h"
#include "addr.h"
#include "node.h"
#include <net/genetlink.h>

#define TIPC_NAMETBL_SIZE 1024          /* must be a power of 2 */

/**
 * struct name_info - name sequence publication info
 * @node_list: circular list of publications made by own node
 * @cluster_list: circular list of publications made by own cluster
 * @zone_list: circular list of publications made by own zone
 * @node_list_size: number of entries in "node_list"
 * @cluster_list_size: number of entries in "cluster_list"
 * @zone_list_size: number of entries in "zone_list"
 *
 * Note: The zone list always contains at least one entry, since all
 *       publications of the associated name sequence belong to it.
 *       (The cluster and node lists may be empty.)
 */
struct name_info {
        struct list_head node_list;
        struct list_head cluster_list;
        struct list_head zone_list;
        u32 node_list_size;
        u32 cluster_list_size;
        u32 zone_list_size;
};

/**
 * struct sub_seq - container for all published instances of a name sequence
 * @lower: name sequence lower bound
 * @upper: name sequence upper bound
 * @info: pointer to name sequence publication info
 */
struct sub_seq {
        u32 lower;
        u32 upper;
        struct name_info *info;
};

/**
 * struct name_seq - container for all published instances of a name type
 * @type: 32 bit 'type' value for name sequence
 * @sseq: pointer to dynamically-sized array of sub-sequences of this 'type';
 *        sub-sequences are sorted in ascending order
 * @alloc: number of sub-sequences currently in array
 * @first_free: array index of first unused sub-sequence entry
 * @ns_list: links to adjacent name sequences in hash chain
 * @subscriptions: list of subscriptions for this 'type'
 * @lock: spinlock controlling access to publication lists of all sub-sequences
 * @rcu: RCU callback head used for deferred freeing
 */
struct name_seq {
        u32 type;
        struct sub_seq *sseqs;
        u32 alloc;
        u32 first_free;
        struct hlist_node ns_list;
        struct list_head subscriptions;
        spinlock_t lock;
        struct rcu_head rcu;
};

static int hash(int x)
{
        return x & (TIPC_NAMETBL_SIZE - 1);
}

/**
 * publ_create - create a publication structure
 */
static struct publication *publ_create(u32 type, u32 lower, u32 upper,
                                       u32 scope, u32 node, u32 port_ref,
                                       u32 key)
{
        struct publication *publ = kzalloc(sizeof(*publ), GFP_ATOMIC);
        if (publ == NULL) {
                pr_warn("Publication creation failure, no memory\n");
                return NULL;
        }

        publ->type = type;
        publ->lower = lower;
        publ->upper = upper;
        publ->scope = scope;
        publ->node = node;
        publ->ref = port_ref;
        publ->key = key;
        INIT_LIST_HEAD(&publ->pport_list);
        return publ;
}

/**
 * tipc_subseq_alloc - allocate a specified number of sub-sequence structures
 */
static struct sub_seq *tipc_subseq_alloc(u32 cnt)
{
        return kcalloc(cnt, sizeof(struct sub_seq), GFP_ATOMIC);
}

/**
 * tipc_nameseq_create - create a name sequence structure for the specified 'type'
 *
 * Allocates a single sub-sequence structure and sets it to all 0's.
 */
static struct name_seq *tipc_nameseq_create(u32 type, struct hlist_head *seq_head)
{
        struct name_seq *nseq = kzalloc(sizeof(*nseq), GFP_ATOMIC);
        struct sub_seq *sseq = tipc_subseq_alloc(1);

        if (!nseq || !sseq) {
                pr_warn("Name sequence creation failed, no memory\n");
                kfree(nseq);
                kfree(sseq);
                return NULL;
        }

        spin_lock_init(&nseq->lock);
        nseq->type = type;
        nseq->sseqs = sseq;
        nseq->alloc = 1;
        INIT_HLIST_NODE(&nseq->ns_list);
        INIT_LIST_HEAD(&nseq->subscriptions);
        hlist_add_head_rcu(&nseq->ns_list, seq_head);
        return nseq;
}

/**
 * nameseq_find_subseq - find sub-sequence (if any) matching a name instance
 *
 * Very time-critical, so binary searches through sub-sequence array.
 */
static struct sub_seq *nameseq_find_subseq(struct name_seq *nseq,
                                           u32 instance)
{
        struct sub_seq *sseqs = nseq->sseqs;
        int low = 0;
        int high = nseq->first_free - 1;
        int mid;

        while (low <= high) {
                mid = (low + high) / 2;
                if (instance < sseqs[mid].lower)
                        high = mid - 1;
                else if (instance > sseqs[mid].upper)
                        low = mid + 1;
                else
                        return &sseqs[mid];
        }
        return NULL;
}

/**
 * nameseq_locate_subseq - determine position of name instance in sub-sequence
 *
 * Returns index in sub-sequence array of the entry that contains the specified
 * instance value; if no entry contains that value, returns the position
 * where a new entry for it would be inserted in the array.
 *
 * Note: Similar to binary search code for locating a sub-sequence.
 */
static u32 nameseq_locate_subseq(struct name_seq *nseq, u32 instance)
{
        struct sub_seq *sseqs = nseq->sseqs;
        int low = 0;
        int high = nseq->first_free - 1;
        int mid;

        while (low <= high) {
                mid = (low + high) / 2;
                if (instance < sseqs[mid].lower)
                        high = mid - 1;
                else if (instance > sseqs[mid].upper)
                        low = mid + 1;
                else
                        return mid;
        }
        return low;
}

/**
 * tipc_nameseq_insert_publ
 */
static struct publication *tipc_nameseq_insert_publ(struct net *net,
                                                    struct name_seq *nseq,
                                                    u32 type, u32 lower,
                                                    u32 upper, u32 scope,
                                                    u32 node, u32 port, u32 key)
{
        struct tipc_subscription *s;
        struct tipc_subscription *st;
        struct publication *publ;
        struct sub_seq *sseq;
        struct name_info *info;
        int created_subseq = 0;

        sseq = nameseq_find_subseq(nseq, lower);
        if (sseq) {

                /* Lower end overlaps existing entry => need an exact match */
                if ((sseq->lower != lower) || (sseq->upper != upper)) {
                        return NULL;
                }

                info = sseq->info;

                /* Check if an identical publication already exists */
                list_for_each_entry(publ, &info->zone_list, zone_list) {
                        if ((publ->ref == port) && (publ->key == key) &&
                            (!publ->node || (publ->node == node)))
                                return NULL;
                }
        } else {
                u32 inspos;
                struct sub_seq *freesseq;

                /* Find where lower end should be inserted */
                inspos = nameseq_locate_subseq(nseq, lower);

                /* Fail if upper end overlaps into an existing entry */
                if ((inspos < nseq->first_free) &&
                    (upper >= nseq->sseqs[inspos].lower)) {
                        return NULL;
                }

                /* Ensure there is space for new sub-sequence */
                if (nseq->first_free == nseq->alloc) {
                        struct sub_seq *sseqs = tipc_subseq_alloc(nseq->alloc * 2);

                        if (!sseqs) {
                                pr_warn("Cannot publish {%u,%u,%u}, no memory\n",
                                        type, lower, upper);
                                return NULL;
                        }
                        memcpy(sseqs, nseq->sseqs,
                               nseq->alloc * sizeof(struct sub_seq));
                        kfree(nseq->sseqs);
                        nseq->sseqs = sseqs;
                        nseq->alloc *= 2;
                }

                info = kzalloc(sizeof(*info), GFP_ATOMIC);
                if (!info) {
                        pr_warn("Cannot publish {%u,%u,%u}, no memory\n",
                                type, lower, upper);
                        return NULL;
                }

                INIT_LIST_HEAD(&info->node_list);
                INIT_LIST_HEAD(&info->cluster_list);
                INIT_LIST_HEAD(&info->zone_list);

                /* Insert new sub-sequence */
                sseq = &nseq->sseqs[inspos];
                freesseq = &nseq->sseqs[nseq->first_free];
                memmove(sseq + 1, sseq, (freesseq - sseq) * sizeof(*sseq));
                memset(sseq, 0, sizeof(*sseq));
                nseq->first_free++;
                sseq->lower = lower;
                sseq->upper = upper;
                sseq->info = info;
                created_subseq = 1;
        }

        /* Insert a publication */
        publ = publ_create(type, lower, upper, scope, node, port, key);
        if (!publ)
                return NULL;

        list_add(&publ->zone_list, &info->zone_list);
        info->zone_list_size++;

        if (in_own_cluster(net, node)) {
                list_add(&publ->cluster_list, &info->cluster_list);
                info->cluster_list_size++;
        }

        if (in_own_node(net, node)) {
                list_add(&publ->node_list, &info->node_list);
                info->node_list_size++;
        }

        /* Any subscriptions waiting for notification?  */
        list_for_each_entry_safe(s, st, &nseq->subscriptions, nameseq_list) {
                tipc_subscrp_report_overlap(s, publ->lower, publ->upper,
                                            TIPC_PUBLISHED, publ->ref,
                                            publ->node, created_subseq);
        }
        return publ;
}

/**
 * tipc_nameseq_remove_publ
 *
 * NOTE: There may be cases where TIPC is asked to remove a publication
 * that is not in the name table.  For example, if another node issues a
 * publication for a name sequence that overlaps an existing name sequence
 * the publication will not be recorded, which means the publication won't
 * be found when the name sequence is later withdrawn by that node.
 * A failed withdraw request simply returns a failure indication and lets the
 * caller issue any error or warning messages associated with such a problem.
 */
static struct publication *tipc_nameseq_remove_publ(struct net *net,
                                                    struct name_seq *nseq,
                                                    u32 inst, u32 node,
                                                    u32 ref, u32 key)
{
        struct publication *publ;
        struct sub_seq *sseq = nameseq_find_subseq(nseq, inst);
        struct name_info *info;
        struct sub_seq *free;
        struct tipc_subscription *s, *st;
        int removed_subseq = 0;

        if (!sseq)
                return NULL;

        info = sseq->info;

        /* Locate publication, if it exists */
        list_for_each_entry(publ, &info->zone_list, zone_list) {
                if ((publ->key == key) && (publ->ref == ref) &&
                    (!publ->node || (publ->node == node)))
                        goto found;
        }
        return NULL;

found:
        /* Remove publication from zone scope list */
        list_del(&publ->zone_list);
        info->zone_list_size--;

        /* Remove publication from cluster scope list, if present */
        if (in_own_cluster(net, node)) {
                list_del(&publ->cluster_list);
                info->cluster_list_size--;
        }

        /* Remove publication from node scope list, if present */
        if (in_own_node(net, node)) {
                list_del(&publ->node_list);
                info->node_list_size--;
        }

        /* Contract subseq list if no more publications for that subseq */
        if (list_empty(&info->zone_list)) {
                kfree(info);
                free = &nseq->sseqs[nseq->first_free--];
                memmove(sseq, sseq + 1, (free - (sseq + 1)) * sizeof(*sseq));
                removed_subseq = 1;
        }

        /* Notify any waiting subscriptions */
        list_for_each_entry_safe(s, st, &nseq->subscriptions, nameseq_list) {
                tipc_subscrp_report_overlap(s, publ->lower, publ->upper,
                                            TIPC_WITHDRAWN, publ->ref,
                                            publ->node, removed_subseq);
        }

        return publ;
}

/**
 * tipc_nameseq_subscribe - attach a subscription, and issue
 * the prescribed number of events if there is any sub-
 * sequence overlapping with the requested sequence
 */
static void tipc_nameseq_subscribe(struct name_seq *nseq,
                                   struct tipc_subscription *s)
{
        struct sub_seq *sseq = nseq->sseqs;
        struct tipc_name_seq ns;

        tipc_subscrp_convert_seq(&s->evt.s.seq, s->swap, &ns);

        tipc_subscrp_get(s);
        list_add(&s->nameseq_list, &nseq->subscriptions);

        if (!sseq)
                return;

        while (sseq != &nseq->sseqs[nseq->first_free]) {
                if (tipc_subscrp_check_overlap(&ns, sseq->lower, sseq->upper)) {
                        struct publication *crs;
                        struct name_info *info = sseq->info;
                        int must_report = 1;

                        list_for_each_entry(crs, &info->zone_list, zone_list) {
                                tipc_subscrp_report_overlap(s, sseq->lower,
                                                            sseq->upper,
                                                            TIPC_PUBLISHED,
                                                            crs->ref, crs->node,
                                                            must_report);
                                must_report = 0;
                        }
                }
                sseq++;
        }
}

static struct name_seq *nametbl_find_seq(struct net *net, u32 type)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct hlist_head *seq_head;
        struct name_seq *ns;

        seq_head = &tn->nametbl->seq_hlist[hash(type)];
        hlist_for_each_entry_rcu(ns, seq_head, ns_list) {
                if (ns->type == type)
                        return ns;
        }

        return NULL;
};

struct publication *tipc_nametbl_insert_publ(struct net *net, u32 type,
                                             u32 lower, u32 upper, u32 scope,
                                             u32 node, u32 port, u32 key)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct publication *publ;
        struct name_seq *seq = nametbl_find_seq(net, type);
        int index = hash(type);

        if ((scope < TIPC_ZONE_SCOPE) || (scope > TIPC_NODE_SCOPE) ||
            (lower > upper)) {
                pr_debug("Failed to publish illegal {%u,%u,%u} with scope %u\n",
                         type, lower, upper, scope);
                return NULL;
        }

        if (!seq)
                seq = tipc_nameseq_create(type, &tn->nametbl->seq_hlist[index]);
        if (!seq)
                return NULL;

        spin_lock_bh(&seq->lock);
        publ = tipc_nameseq_insert_publ(net, seq, type, lower, upper,
                                        scope, node, port, key);
        spin_unlock_bh(&seq->lock);
        return publ;
}

struct publication *tipc_nametbl_remove_publ(struct net *net, u32 type,
                                             u32 lower, u32 node, u32 ref,
                                             u32 key)
{
        struct publication *publ;
        struct name_seq *seq = nametbl_find_seq(net, type);

        if (!seq)
                return NULL;

        spin_lock_bh(&seq->lock);
        publ = tipc_nameseq_remove_publ(net, seq, lower, node, ref, key);
        if (!seq->first_free && list_empty(&seq->subscriptions)) {
                hlist_del_init_rcu(&seq->ns_list);
                kfree(seq->sseqs);
                spin_unlock_bh(&seq->lock);
                kfree_rcu(seq, rcu);
                return publ;
        }
        spin_unlock_bh(&seq->lock);
        return publ;
}

/**
 * tipc_nametbl_translate - perform name translation
 *
 * On entry, 'destnode' is the search domain used during translation.
 *
 * On exit:
 * - if name translation is deferred to another node/cluster/zone,
 *   leaves 'destnode' unchanged (will be non-zero) and returns 0
 * - if name translation is attempted and succeeds, sets 'destnode'
 *   to publishing node and returns port reference (will be non-zero)
 * - if name translation is attempted and fails, sets 'destnode' to 0
 *   and returns 0
 */
u32 tipc_nametbl_translate(struct net *net, u32 type, u32 instance,
                           u32 *destnode)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct sub_seq *sseq;
        struct name_info *info;
        struct publication *publ;
        struct name_seq *seq;
        u32 ref = 0;
        u32 node = 0;

        if (!tipc_in_scope(*destnode, tn->own_addr))
                return 0;

        rcu_read_lock();
        seq = nametbl_find_seq(net, type);
        if (unlikely(!seq))
                goto not_found;
        spin_lock_bh(&seq->lock);
        sseq = nameseq_find_subseq(seq, instance);
        if (unlikely(!sseq))
                goto no_match;
        info = sseq->info;

        /* Closest-First Algorithm */
        if (likely(!*destnode)) {
                if (!list_empty(&info->node_list)) {
                        publ = list_first_entry(&info->node_list,
                                                struct publication,
                                                node_list);
                        list_move_tail(&publ->node_list,
                                       &info->node_list);
                } else if (!list_empty(&info->cluster_list)) {
                        publ = list_first_entry(&info->cluster_list,
                                                struct publication,
                                                cluster_list);
                        list_move_tail(&publ->cluster_list,
                                       &info->cluster_list);
                } else {
                        publ = list_first_entry(&info->zone_list,
                                                struct publication,
                                                zone_list);
                        list_move_tail(&publ->zone_list,
                                       &info->zone_list);
                }
        }

        /* Round-Robin Algorithm */
        else if (*destnode == tn->own_addr) {
                if (list_empty(&info->node_list))
                        goto no_match;
                publ = list_first_entry(&info->node_list, struct publication,
                                        node_list);
                list_move_tail(&publ->node_list, &info->node_list);
        } else if (in_own_cluster_exact(net, *destnode)) {
                if (list_empty(&info->cluster_list))
                        goto no_match;
                publ = list_first_entry(&info->cluster_list, struct publication,
                                        cluster_list);
                list_move_tail(&publ->cluster_list, &info->cluster_list);
        } else {
                publ = list_first_entry(&info->zone_list, struct publication,
                                        zone_list);
                list_move_tail(&publ->zone_list, &info->zone_list);
        }

        ref = publ->ref;
        node = publ->node;
no_match:
        spin_unlock_bh(&seq->lock);
not_found:
        rcu_read_unlock();
        *destnode = node;
        return ref;
}

/**
 * tipc_nametbl_mc_translate - find multicast destinations
 *
 * Creates list of all local ports that overlap the given multicast address;
 * also determines if any off-node ports overlap.
 *
 * Note: Publications with a scope narrower than 'limit' are ignored.
 * (i.e. local node-scope publications mustn't receive messages arriving
 * from another node, even if the multcast link brought it here)
 *
 * Returns non-zero if any off-node ports overlap
 */
int tipc_nametbl_mc_translate(struct net *net, u32 type, u32 lower, u32 upper,
                              u32 limit, struct list_head *dports)
{
        struct name_seq *seq;
        struct sub_seq *sseq;
        struct sub_seq *sseq_stop;
        struct name_info *info;
        int res = 0;

        rcu_read_lock();
        seq = nametbl_find_seq(net, type);
        if (!seq)
                goto exit;

        spin_lock_bh(&seq->lock);
        sseq = seq->sseqs + nameseq_locate_subseq(seq, lower);
        sseq_stop = seq->sseqs + seq->first_free;
        for (; sseq != sseq_stop; sseq++) {
                struct publication *publ;

                if (sseq->lower > upper)
                        break;

                info = sseq->info;
                list_for_each_entry(publ, &info->node_list, node_list) {
                        if (publ->scope <= limit)
                                u32_push(dports, publ->ref);
                }

                if (info->cluster_list_size != info->node_list_size)
                        res = 1;
        }
        spin_unlock_bh(&seq->lock);
exit:
        rcu_read_unlock();
        return res;
}

/* tipc_nametbl_lookup_dst_nodes - find broadcast destination nodes
 * - Creates list of nodes that overlap the given multicast address
 * - Determines if any node local ports overlap
 */
void tipc_nametbl_lookup_dst_nodes(struct net *net, u32 type, u32 lower,
                                   u32 upper, u32 domain,
                                   struct tipc_nlist *nodes)
{
        struct sub_seq *sseq, *stop;
        struct publication *publ;
        struct name_info *info;
        struct name_seq *seq;

        rcu_read_lock();
        seq = nametbl_find_seq(net, type);
        if (!seq)
                goto exit;

        spin_lock_bh(&seq->lock);
        sseq = seq->sseqs + nameseq_locate_subseq(seq, lower);
        stop = seq->sseqs + seq->first_free;
        for (; sseq->lower <= upper && sseq != stop; sseq++) {
                info = sseq->info;
                list_for_each_entry(publ, &info->zone_list, zone_list) {
                        if (tipc_in_scope(domain, publ->node))
                                tipc_nlist_add(nodes, publ->node);
                }
        }
        spin_unlock_bh(&seq->lock);
exit:
        rcu_read_unlock();
}

/*
 * tipc_nametbl_publish - add name publication to network name tables
 */
struct publication *tipc_nametbl_publish(struct net *net, u32 type, u32 lower,
                                         u32 upper, u32 scope, u32 port_ref,
                                         u32 key)
{
        struct publication *publ;
        struct sk_buff *buf = NULL;
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        spin_lock_bh(&tn->nametbl_lock);
        if (tn->nametbl->local_publ_count >= TIPC_MAX_PUBLICATIONS) {
                pr_warn("Publication failed, local publication limit reached (%u)\n",
                        TIPC_MAX_PUBLICATIONS);
                spin_unlock_bh(&tn->nametbl_lock);
                return NULL;
        }

        publ = tipc_nametbl_insert_publ(net, type, lower, upper, scope,
                                        tn->own_addr, port_ref, key);
        if (likely(publ)) {
                tn->nametbl->local_publ_count++;
                buf = tipc_named_publish(net, publ);
                /* Any pending external events? */
                tipc_named_process_backlog(net);
        }
        spin_unlock_bh(&tn->nametbl_lock);

        if (buf)
                tipc_node_broadcast(net, buf);
        return publ;
}

/**
 * tipc_nametbl_withdraw - withdraw name publication from network name tables
 */
int tipc_nametbl_withdraw(struct net *net, u32 type, u32 lower, u32 ref,
                          u32 key)
{
        struct publication *publ;
        struct sk_buff *skb = NULL;
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        spin_lock_bh(&tn->nametbl_lock);
        publ = tipc_nametbl_remove_publ(net, type, lower, tn->own_addr,
                                        ref, key);
        if (likely(publ)) {
                tn->nametbl->local_publ_count--;
                skb = tipc_named_withdraw(net, publ);
                /* Any pending external events? */
                tipc_named_process_backlog(net);
                list_del_init(&publ->pport_list);
                kfree_rcu(publ, rcu);
        } else {
                pr_err("Unable to remove local publication\n"
                       "(type=%u, lower=%u, ref=%u, key=%u)\n",
                       type, lower, ref, key);
        }
        spin_unlock_bh(&tn->nametbl_lock);

        if (skb) {
                tipc_node_broadcast(net, skb);
                return 1;
        }
        return 0;
}

/**
 * tipc_nametbl_subscribe - add a subscription object to the name table
 */
void tipc_nametbl_subscribe(struct tipc_subscription *s)
{
        struct tipc_net *tn = net_generic(s->net, tipc_net_id);
        u32 type = tipc_subscrp_convert_seq_type(s->evt.s.seq.type, s->swap);
        int index = hash(type);
        struct name_seq *seq;
        struct tipc_name_seq ns;

        spin_lock_bh(&tn->nametbl_lock);
        seq = nametbl_find_seq(s->net, type);
        if (!seq)
                seq = tipc_nameseq_create(type, &tn->nametbl->seq_hlist[index]);
        if (seq) {
                spin_lock_bh(&seq->lock);
                tipc_nameseq_subscribe(seq, s);
                spin_unlock_bh(&seq->lock);
        } else {
                tipc_subscrp_convert_seq(&s->evt.s.seq, s->swap, &ns);
                pr_warn("Failed to create subscription for {%u,%u,%u}\n",
                        ns.type, ns.lower, ns.upper);
        }
        spin_unlock_bh(&tn->nametbl_lock);
}

/**
 * tipc_nametbl_unsubscribe - remove a subscription object from name table
 */
void tipc_nametbl_unsubscribe(struct tipc_subscription *s)
{
        struct tipc_net *tn = net_generic(s->net, tipc_net_id);
        struct name_seq *seq;
        u32 type = tipc_subscrp_convert_seq_type(s->evt.s.seq.type, s->swap);

        spin_lock_bh(&tn->nametbl_lock);
        seq = nametbl_find_seq(s->net, type);
        if (seq != NULL) {
                spin_lock_bh(&seq->lock);
                list_del_init(&s->nameseq_list);
                tipc_subscrp_put(s);
                if (!seq->first_free && list_empty(&seq->subscriptions)) {
                        hlist_del_init_rcu(&seq->ns_list);
                        kfree(seq->sseqs);
                        spin_unlock_bh(&seq->lock);
                        kfree_rcu(seq, rcu);
                } else {
                        spin_unlock_bh(&seq->lock);
                }
        }
        spin_unlock_bh(&tn->nametbl_lock);
}

int tipc_nametbl_init(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct name_table *tipc_nametbl;
        int i;

        tipc_nametbl = kzalloc(sizeof(*tipc_nametbl), GFP_ATOMIC);
        if (!tipc_nametbl)
                return -ENOMEM;

        for (i = 0; i < TIPC_NAMETBL_SIZE; i++)
                INIT_HLIST_HEAD(&tipc_nametbl->seq_hlist[i]);

        INIT_LIST_HEAD(&tipc_nametbl->publ_list[TIPC_ZONE_SCOPE]);
        INIT_LIST_HEAD(&tipc_nametbl->publ_list[TIPC_CLUSTER_SCOPE]);
        INIT_LIST_HEAD(&tipc_nametbl->publ_list[TIPC_NODE_SCOPE]);
        tn->nametbl = tipc_nametbl;
        spin_lock_init(&tn->nametbl_lock);
        return 0;
}

/**
 * tipc_purge_publications - remove all publications for a given type
 *
 * tipc_nametbl_lock must be held when calling this function
 */
static void tipc_purge_publications(struct net *net, struct name_seq *seq)
{
        struct publication *publ, *safe;
        struct sub_seq *sseq;
        struct name_info *info;

        spin_lock_bh(&seq->lock);
        sseq = seq->sseqs;
        info = sseq->info;
        list_for_each_entry_safe(publ, safe, &info->zone_list, zone_list) {
                tipc_nameseq_remove_publ(net, seq, publ->lower, publ->node,
                                         publ->ref, publ->key);
                kfree_rcu(publ, rcu);
        }
        hlist_del_init_rcu(&seq->ns_list);
        kfree(seq->sseqs);
        spin_unlock_bh(&seq->lock);

        kfree_rcu(seq, rcu);
}

void tipc_nametbl_stop(struct net *net)
{
        u32 i;
        struct name_seq *seq;
        struct hlist_head *seq_head;
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct name_table *tipc_nametbl = tn->nametbl;

        /* Verify name table is empty and purge any lingering
         * publications, then release the name table
         */
        spin_lock_bh(&tn->nametbl_lock);
        for (i = 0; i < TIPC_NAMETBL_SIZE; i++) {
                if (hlist_empty(&tipc_nametbl->seq_hlist[i]))
                        continue;
                seq_head = &tipc_nametbl->seq_hlist[i];
                hlist_for_each_entry_rcu(seq, seq_head, ns_list) {
                        tipc_purge_publications(net, seq);
                }
        }
        spin_unlock_bh(&tn->nametbl_lock);

        synchronize_net();
        kfree(tipc_nametbl);

}

static int __tipc_nl_add_nametable_publ(struct tipc_nl_msg *msg,
                                        struct name_seq *seq,
                                        struct sub_seq *sseq, u32 *last_publ)
{
        void *hdr;
        struct nlattr *attrs;
        struct nlattr *publ;
        struct publication *p;

        if (*last_publ) {
                list_for_each_entry(p, &sseq->info->zone_list, zone_list)
                        if (p->key == *last_publ)
                                break;
                if (p->key != *last_publ)
                        return -EPIPE;
        } else {
                p = list_first_entry(&sseq->info->zone_list, struct publication,
                                     zone_list);
        }

        list_for_each_entry_from(p, &sseq->info->zone_list, zone_list) {
                *last_publ = p->key;

                hdr = genlmsg_put(msg->skb, msg->portid, msg->seq,
                                  &tipc_genl_family, NLM_F_MULTI,
                                  TIPC_NL_NAME_TABLE_GET);
                if (!hdr)
                        return -EMSGSIZE;

                attrs = nla_nest_start(msg->skb, TIPC_NLA_NAME_TABLE);
                if (!attrs)
                        goto msg_full;

                publ = nla_nest_start(msg->skb, TIPC_NLA_NAME_TABLE_PUBL);
                if (!publ)
                        goto attr_msg_full;

                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_TYPE, seq->type))
                        goto publ_msg_full;
                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_LOWER, sseq->lower))
                        goto publ_msg_full;
                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_UPPER, sseq->upper))
                        goto publ_msg_full;
                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_SCOPE, p->scope))
                        goto publ_msg_full;
                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_NODE, p->node))
                        goto publ_msg_full;
                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_REF, p->ref))
                        goto publ_msg_full;
                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_KEY, p->key))
                        goto publ_msg_full;

                nla_nest_end(msg->skb, publ);
                nla_nest_end(msg->skb, attrs);
                genlmsg_end(msg->skb, hdr);
        }
        *last_publ = 0;

        return 0;

publ_msg_full:
        nla_nest_cancel(msg->skb, publ);
attr_msg_full:
        nla_nest_cancel(msg->skb, attrs);
msg_full:
        genlmsg_cancel(msg->skb, hdr);

        return -EMSGSIZE;
}

static int __tipc_nl_subseq_list(struct tipc_nl_msg *msg, struct name_seq *seq,
                                 u32 *last_lower, u32 *last_publ)
{
        struct sub_seq *sseq;
        struct sub_seq *sseq_start;
        int err;

        if (*last_lower) {
                sseq_start = nameseq_find_subseq(seq, *last_lower);
                if (!sseq_start)
                        return -EPIPE;
        } else {
                sseq_start = seq->sseqs;
        }

        for (sseq = sseq_start; sseq != &seq->sseqs[seq->first_free]; sseq++) {
                err = __tipc_nl_add_nametable_publ(msg, seq, sseq, last_publ);
                if (err) {
                        *last_lower = sseq->lower;
                        return err;
                }
        }
        *last_lower = 0;

        return 0;
}

static int tipc_nl_seq_list(struct net *net, struct tipc_nl_msg *msg,
                            u32 *last_type, u32 *last_lower, u32 *last_publ)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct hlist_head *seq_head;
        struct name_seq *seq = NULL;
        int err;
        int i;

        if (*last_type)
                i = hash(*last_type);
        else
                i = 0;

        for (; i < TIPC_NAMETBL_SIZE; i++) {
                seq_head = &tn->nametbl->seq_hlist[i];

                if (*last_type) {
                        seq = nametbl_find_seq(net, *last_type);
                        if (!seq)
                                return -EPIPE;
                } else {
                        hlist_for_each_entry_rcu(seq, seq_head, ns_list)
                                break;
                        if (!seq)
                                continue;

                }

                hlist_for_each_entry_from_rcu(seq, ns_list) {
                        spin_lock_bh(&seq->lock);
                        err = __tipc_nl_subseq_list(msg, seq, last_lower,
                                                    last_publ);

                        if (err) {
                                *last_type = seq->type;
                                spin_unlock_bh(&seq->lock);
                                return err;
                        }
                        spin_unlock_bh(&seq->lock);
                }
                *last_type = 0;
        }
        return 0;
}

int tipc_nl_name_table_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
        int err;
        int done = cb->args[3];
        u32 last_type = cb->args[0];
        u32 last_lower = cb->args[1];
        u32 last_publ = cb->args[2];
        struct net *net = sock_net(skb->sk);
        struct tipc_nl_msg msg;

        if (done)
                return 0;

        msg.skb = skb;
        msg.portid = NETLINK_CB(cb->skb).portid;
        msg.seq = cb->nlh->nlmsg_seq;

        rcu_read_lock();
        err = tipc_nl_seq_list(net, &msg, &last_type, &last_lower, &last_publ);
        if (!err) {
                done = 1;
        } else if (err != -EMSGSIZE) {
                /* We never set seq or call nl_dump_check_consistent() this
                 * means that setting prev_seq here will cause the consistence
                 * check to fail in the netlink callback handler. Resulting in
                 * the NLMSG_DONE message having the NLM_F_DUMP_INTR flag set if
                 * we got an error.
                 */
                cb->prev_seq = 1;
        }
        rcu_read_unlock();

        cb->args[0] = last_type;
        cb->args[1] = last_lower;
        cb->args[2] = last_publ;
        cb->args[3] = done;

        return skb->len;
}

bool u32_find(struct list_head *l, u32 value)
{
        struct u32_item *item;

        list_for_each_entry(item, l, list) {
                if (item->value == value)
                        return true;
        }
        return false;
}

bool u32_push(struct list_head *l, u32 value)
{
        struct u32_item *item;

        list_for_each_entry(item, l, list) {
                if (item->value == value)
                        return false;
        }
        item = kmalloc(sizeof(*item), GFP_ATOMIC);
        if (unlikely(!item))
                return false;

        item->value = value;
        list_add(&item->list, l);
        return true;
}

u32 u32_pop(struct list_head *l)
{
        struct u32_item *item;
        u32 value = 0;

        if (list_empty(l))
                return 0;
        item = list_first_entry(l, typeof(*item), list);
        value = item->value;
        list_del(&item->list);
        kfree(item);
        return value;
}

bool u32_del(struct list_head *l, u32 value)
{
        struct u32_item *item, *tmp;

        list_for_each_entry_safe(item, tmp, l, list) {
                if (item->value != value)
                        continue;
                list_del(&item->list);
                kfree(item);
                return true;
        }
        return false;
}

void u32_list_purge(struct list_head *l)
{
        struct u32_item *item, *tmp;

        list_for_each_entry_safe(item, tmp, l, list) {
                list_del(&item->list);
                kfree(item);
        }
}

int u32_list_len(struct list_head *l)
{
        struct u32_item *item;
        int i = 0;

        list_for_each_entry(item, l, list) {
                i++;
        }
        return i;
}