Merge tag '20201024-v4-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wtarrea...

[mirror_ubuntu-jammy-kernel.git] / net / tipc / name_table.c

/*
 * net/tipc/name_table.c: TIPC name table code
 *
 * Copyright (c) 2000-2006, 2014-2018, 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 <linux/list_sort.h>
#include <linux/rbtree_augmented.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 "group.h"

/**
 * struct service_range - container for all bindings of a service range
 * @lower: service range lower bound
 * @upper: service range upper bound
 * @tree_node: member of service range RB tree
 * @max: largest 'upper' in this node subtree
 * @local_publ: list of identical publications made from this node
 *   Used by closest_first lookup and multicast lookup algorithm
 * @all_publ: all publications identical to this one, whatever node and scope
 *   Used by round-robin lookup algorithm
 */
struct service_range {
        u32 lower;
        u32 upper;
        struct rb_node tree_node;
        u32 max;
        struct list_head local_publ;
        struct list_head all_publ;
};

/**
 * struct tipc_service - container for all published instances of a service type
 * @type: 32 bit 'type' value for service
 * @publ_cnt: increasing counter for publications in this service
 * @ranges: rb tree containing all service ranges for this service
 * @service_list: links to adjacent name ranges in hash chain
 * @subscriptions: list of subscriptions for this service type
 * @lock: spinlock controlling access to pertaining service ranges/publications
 * @rcu: RCU callback head used for deferred freeing
 */
struct tipc_service {
        u32 type;
        u32 publ_cnt;
        struct rb_root ranges;
        struct hlist_node service_list;
        struct list_head subscriptions;
        spinlock_t lock; /* Covers service range list */
        struct rcu_head rcu;
};

#define service_range_upper(sr) ((sr)->upper)
RB_DECLARE_CALLBACKS_MAX(static, sr_callbacks,
                         struct service_range, tree_node, u32, max,
                         service_range_upper)

#define service_range_entry(rbtree_node)                                \
        (container_of(rbtree_node, struct service_range, tree_node))

#define service_range_overlap(sr, start, end)                           \
        ((sr)->lower <= (end) && (sr)->upper >= (start))

/**
 * service_range_foreach_match - iterate over tipc service rbtree for each
 *                               range match
 * @sr: the service range pointer as a loop cursor
 * @sc: the pointer to tipc service which holds the service range rbtree
 * @start, end: the range (end >= start) for matching
 */
#define service_range_foreach_match(sr, sc, start, end)                 \
        for (sr = service_range_match_first((sc)->ranges.rb_node,       \
                                            start,                      \
                                            end);                       \
             sr;                                                        \
             sr = service_range_match_next(&(sr)->tree_node,            \
                                           start,                       \
                                           end))

/**
 * service_range_match_first - find first service range matching a range
 * @n: the root node of service range rbtree for searching
 * @start, end: the range (end >= start) for matching
 *
 * Return: the leftmost service range node in the rbtree that overlaps the
 * specific range if any. Otherwise, returns NULL.
 */
static struct service_range *service_range_match_first(struct rb_node *n,
                                                       u32 start, u32 end)
{
        struct service_range *sr;
        struct rb_node *l, *r;

        /* Non overlaps in tree at all? */
        if (!n || service_range_entry(n)->max < start)
                return NULL;

        while (n) {
                l = n->rb_left;
                if (l && service_range_entry(l)->max >= start) {
                        /* A leftmost overlap range node must be one in the left
                         * subtree. If not, it has lower > end, then nodes on
                         * the right side cannot satisfy the condition either.
                         */
                        n = l;
                        continue;
                }

                /* No one in the left subtree can match, return if this node is
                 * an overlap i.e. leftmost.
                 */
                sr = service_range_entry(n);
                if (service_range_overlap(sr, start, end))
                        return sr;

                /* Ok, try to lookup on the right side */
                r = n->rb_right;
                if (sr->lower <= end &&
                    r && service_range_entry(r)->max >= start) {
                        n = r;
                        continue;
                }
                break;
        }

        return NULL;
}

/**
 * service_range_match_next - find next service range matching a range
 * @n: a node in service range rbtree from which the searching starts
 * @start, end: the range (end >= start) for matching
 *
 * Return: the next service range node to the given node in the rbtree that
 * overlaps the specific range if any. Otherwise, returns NULL.
 */
static struct service_range *service_range_match_next(struct rb_node *n,
                                                      u32 start, u32 end)
{
        struct service_range *sr;
        struct rb_node *p, *r;

        while (n) {
                r = n->rb_right;
                if (r && service_range_entry(r)->max >= start)
                        /* A next overlap range node must be one in the right
                         * subtree. If not, it has lower > end, then any next
                         * successor (- an ancestor) of this node cannot
                         * satisfy the condition either.
                         */
                        return service_range_match_first(r, start, end);

                /* No one in the right subtree can match, go up to find an
                 * ancestor of this node which is parent of a left-hand child.
                 */
                while ((p = rb_parent(n)) && n == p->rb_right)
                        n = p;
                if (!p)
                        break;

                /* Return if this ancestor is an overlap */
                sr = service_range_entry(p);
                if (service_range_overlap(sr, start, end))
                        return sr;

                /* Ok, try to lookup more from this ancestor */
                if (sr->lower <= end) {
                        n = p;
                        continue;
                }
                break;
        }

        return NULL;
}

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

/**
 * tipc_publ_create - create a publication structure
 */
static struct publication *tipc_publ_create(u32 type, u32 lower, u32 upper,
                                            u32 scope, u32 node, u32 port,
                                            u32 key)
{
        struct publication *publ = kzalloc(sizeof(*publ), GFP_ATOMIC);

        if (!publ)
                return NULL;

        publ->type = type;
        publ->lower = lower;
        publ->upper = upper;
        publ->scope = scope;
        publ->node = node;
        publ->port = port;
        publ->key = key;
        INIT_LIST_HEAD(&publ->binding_sock);
        INIT_LIST_HEAD(&publ->binding_node);
        INIT_LIST_HEAD(&publ->local_publ);
        INIT_LIST_HEAD(&publ->all_publ);
        INIT_LIST_HEAD(&publ->list);
        return publ;
}

/**
 * tipc_service_create - create a service structure for the specified 'type'
 *
 * Allocates a single range structure and sets it to all 0's.
 */
static struct tipc_service *tipc_service_create(u32 type, struct hlist_head *hd)
{
        struct tipc_service *service = kzalloc(sizeof(*service), GFP_ATOMIC);

        if (!service) {
                pr_warn("Service creation failed, no memory\n");
                return NULL;
        }

        spin_lock_init(&service->lock);
        service->type = type;
        service->ranges = RB_ROOT;
        INIT_HLIST_NODE(&service->service_list);
        INIT_LIST_HEAD(&service->subscriptions);
        hlist_add_head_rcu(&service->service_list, hd);
        return service;
}

/*  tipc_service_find_range - find service range matching publication parameters
 */
static struct service_range *tipc_service_find_range(struct tipc_service *sc,
                                                     u32 lower, u32 upper)
{
        struct service_range *sr;

        service_range_foreach_match(sr, sc, lower, upper) {
                /* Look for exact match */
                if (sr->lower == lower && sr->upper == upper)
                        return sr;
        }

        return NULL;
}

static struct service_range *tipc_service_create_range(struct tipc_service *sc,
                                                       u32 lower, u32 upper)
{
        struct rb_node **n, *parent = NULL;
        struct service_range *sr;

        n = &sc->ranges.rb_node;
        while (*n) {
                parent = *n;
                sr = service_range_entry(parent);
                if (lower == sr->lower && upper == sr->upper)
                        return sr;
                if (sr->max < upper)
                        sr->max = upper;
                if (lower <= sr->lower)
                        n = &parent->rb_left;
                else
                        n = &parent->rb_right;
        }
        sr = kzalloc(sizeof(*sr), GFP_ATOMIC);
        if (!sr)
                return NULL;
        sr->lower = lower;
        sr->upper = upper;
        sr->max = upper;
        INIT_LIST_HEAD(&sr->local_publ);
        INIT_LIST_HEAD(&sr->all_publ);
        rb_link_node(&sr->tree_node, parent, n);
        rb_insert_augmented(&sr->tree_node, &sc->ranges, &sr_callbacks);
        return sr;
}

static struct publication *tipc_service_insert_publ(struct net *net,
                                                    struct tipc_service *sc,
                                                    u32 type, u32 lower,
                                                    u32 upper, u32 scope,
                                                    u32 node, u32 port,
                                                    u32 key)
{
        struct tipc_subscription *sub, *tmp;
        struct service_range *sr;
        struct publication *p;
        bool first = false;

        sr = tipc_service_create_range(sc, lower, upper);
        if (!sr)
                goto  err;

        first = list_empty(&sr->all_publ);

        /* Return if the publication already exists */
        list_for_each_entry(p, &sr->all_publ, all_publ) {
                if (p->key == key && (!p->node || p->node == node))
                        return NULL;
        }

        /* Create and insert publication */
        p = tipc_publ_create(type, lower, upper, scope, node, port, key);
        if (!p)
                goto err;
        /* Suppose there shouldn't be a huge gap btw publs i.e. >INT_MAX */
        p->id = sc->publ_cnt++;
        if (in_own_node(net, node))
                list_add(&p->local_publ, &sr->local_publ);
        list_add(&p->all_publ, &sr->all_publ);

        /* Any subscriptions waiting for notification?  */
        list_for_each_entry_safe(sub, tmp, &sc->subscriptions, service_list) {
                tipc_sub_report_overlap(sub, p->lower, p->upper, TIPC_PUBLISHED,
                                        p->port, p->node, p->scope, first);
        }
        return p;
err:
        pr_warn("Failed to bind to %u,%u,%u, no memory\n", type, lower, upper);
        return NULL;
}

/**
 * tipc_service_remove_publ - remove a publication from a service
 */
static struct publication *tipc_service_remove_publ(struct service_range *sr,
                                                    u32 node, u32 key)
{
        struct publication *p;

        list_for_each_entry(p, &sr->all_publ, all_publ) {
                if (p->key != key || (node && node != p->node))
                        continue;
                list_del(&p->all_publ);
                list_del(&p->local_publ);
                return p;
        }
        return NULL;
}

/**
 * Code reused: time_after32() for the same purpose
 */
#define publication_after(pa, pb) time_after32((pa)->id, (pb)->id)
static int tipc_publ_sort(void *priv, struct list_head *a,
                          struct list_head *b)
{
        struct publication *pa, *pb;

        pa = container_of(a, struct publication, list);
        pb = container_of(b, struct publication, list);
        return publication_after(pa, pb);
}

/**
 * tipc_service_subscribe - attach a subscription, and optionally
 * issue the prescribed number of events if there is any service
 * range overlapping with the requested range
 */
static void tipc_service_subscribe(struct tipc_service *service,
                                   struct tipc_subscription *sub)
{
        struct tipc_subscr *sb = &sub->evt.s;
        struct publication *p, *first, *tmp;
        struct list_head publ_list;
        struct service_range *sr;
        struct tipc_name_seq ns;
        u32 filter;

        ns.type = tipc_sub_read(sb, seq.type);
        ns.lower = tipc_sub_read(sb, seq.lower);
        ns.upper = tipc_sub_read(sb, seq.upper);
        filter = tipc_sub_read(sb, filter);

        tipc_sub_get(sub);
        list_add(&sub->service_list, &service->subscriptions);

        if (filter & TIPC_SUB_NO_STATUS)
                return;

        INIT_LIST_HEAD(&publ_list);
        service_range_foreach_match(sr, service, ns.lower, ns.upper) {
                first = NULL;
                list_for_each_entry(p, &sr->all_publ, all_publ) {
                        if (filter & TIPC_SUB_PORTS)
                                list_add_tail(&p->list, &publ_list);
                        else if (!first || publication_after(first, p))
                                /* Pick this range's *first* publication */
                                first = p;
                }
                if (first)
                        list_add_tail(&first->list, &publ_list);
        }

        /* Sort the publications before reporting */
        list_sort(NULL, &publ_list, tipc_publ_sort);
        list_for_each_entry_safe(p, tmp, &publ_list, list) {
                tipc_sub_report_overlap(sub, p->lower, p->upper,
                                        TIPC_PUBLISHED, p->port, p->node,
                                        p->scope, true);
                list_del_init(&p->list);
        }
}

static struct tipc_service *tipc_service_find(struct net *net, u32 type)
{
        struct name_table *nt = tipc_name_table(net);
        struct hlist_head *service_head;
        struct tipc_service *service;

        service_head = &nt->services[hash(type)];
        hlist_for_each_entry_rcu(service, service_head, service_list) {
                if (service->type == type)
                        return service;
        }
        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 name_table *nt = tipc_name_table(net);
        struct tipc_service *sc;
        struct publication *p;

        if (scope > TIPC_NODE_SCOPE || lower > upper) {
                pr_debug("Failed to bind illegal {%u,%u,%u} with scope %u\n",
                         type, lower, upper, scope);
                return NULL;
        }
        sc = tipc_service_find(net, type);
        if (!sc)
                sc = tipc_service_create(type, &nt->services[hash(type)]);
        if (!sc)
                return NULL;

        spin_lock_bh(&sc->lock);
        p = tipc_service_insert_publ(net, sc, type, lower, upper,
                                     scope, node, port, key);
        spin_unlock_bh(&sc->lock);
        return p;
}

struct publication *tipc_nametbl_remove_publ(struct net *net, u32 type,
                                             u32 lower, u32 upper,
                                             u32 node, u32 key)
{
        struct tipc_service *sc = tipc_service_find(net, type);
        struct tipc_subscription *sub, *tmp;
        struct service_range *sr = NULL;
        struct publication *p = NULL;
        bool last;

        if (!sc)
                return NULL;

        spin_lock_bh(&sc->lock);
        sr = tipc_service_find_range(sc, lower, upper);
        if (!sr)
                goto exit;
        p = tipc_service_remove_publ(sr, node, key);
        if (!p)
                goto exit;

        /* Notify any waiting subscriptions */
        last = list_empty(&sr->all_publ);
        list_for_each_entry_safe(sub, tmp, &sc->subscriptions, service_list) {
                tipc_sub_report_overlap(sub, lower, upper, TIPC_WITHDRAWN,
                                        p->port, node, p->scope, last);
        }

        /* Remove service range item if this was its last publication */
        if (list_empty(&sr->all_publ)) {
                rb_erase_augmented(&sr->tree_node, &sc->ranges, &sr_callbacks);
                kfree(sr);
        }

        /* Delete service item if this no more publications and subscriptions */
        if (RB_EMPTY_ROOT(&sc->ranges) && list_empty(&sc->subscriptions)) {
                hlist_del_init_rcu(&sc->service_list);
                kfree_rcu(sc, rcu);
        }
exit:
        spin_unlock_bh(&sc->lock);
        return p;
}

/**
 * tipc_nametbl_translate - perform service instance to socket translation
 *
 * On entry, 'dnode' is the search domain used during translation.
 *
 * On exit:
 * - if translation is deferred to another node, leave 'dnode' unchanged and
 *   return 0
 * - if translation is attempted and succeeds, set 'dnode' to the publishing
 *   node and return the published (non-zero) port number
 * - if translation is attempted and fails, set 'dnode' to 0 and return 0
 *
 * Note that for legacy users (node configured with Z.C.N address format) the
 * 'closest-first' lookup algorithm must be maintained, i.e., if dnode is 0
 * we must look in the local binding list first
 */
u32 tipc_nametbl_translate(struct net *net, u32 type, u32 instance, u32 *dnode)
{
        struct tipc_net *tn = tipc_net(net);
        bool legacy = tn->legacy_addr_format;
        u32 self = tipc_own_addr(net);
        struct service_range *sr;
        struct tipc_service *sc;
        struct list_head *list;
        struct publication *p;
        u32 port = 0;
        u32 node = 0;

        if (!tipc_in_scope(legacy, *dnode, self))
                return 0;

        rcu_read_lock();
        sc = tipc_service_find(net, type);
        if (unlikely(!sc))
                goto exit;

        spin_lock_bh(&sc->lock);
        service_range_foreach_match(sr, sc, instance, instance) {
                /* Select lookup algo: local, closest-first or round-robin */
                if (*dnode == self) {
                        list = &sr->local_publ;
                        if (list_empty(list))
                                continue;
                        p = list_first_entry(list, struct publication,
                                             local_publ);
                        list_move_tail(&p->local_publ, &sr->local_publ);
                } else if (legacy && !*dnode && !list_empty(&sr->local_publ)) {
                        list = &sr->local_publ;
                        p = list_first_entry(list, struct publication,
                                             local_publ);
                        list_move_tail(&p->local_publ, &sr->local_publ);
                } else {
                        list = &sr->all_publ;
                        p = list_first_entry(list, struct publication,
                                             all_publ);
                        list_move_tail(&p->all_publ, &sr->all_publ);
                }
                port = p->port;
                node = p->node;
                /* Todo: as for legacy, pick the first matching range only, a
                 * "true" round-robin will be performed as needed.
                 */
                break;
        }
        spin_unlock_bh(&sc->lock);

exit:
        rcu_read_unlock();
        *dnode = node;
        return port;
}

bool tipc_nametbl_lookup(struct net *net, u32 type, u32 instance, u32 scope,
                         struct list_head *dsts, int *dstcnt, u32 exclude,
                         bool all)
{
        u32 self = tipc_own_addr(net);
        struct service_range *sr;
        struct tipc_service *sc;
        struct publication *p;

        *dstcnt = 0;
        rcu_read_lock();
        sc = tipc_service_find(net, type);
        if (unlikely(!sc))
                goto exit;

        spin_lock_bh(&sc->lock);

        /* Todo: a full search i.e. service_range_foreach_match() instead? */
        sr = service_range_match_first(sc->ranges.rb_node, instance, instance);
        if (!sr)
                goto no_match;

        list_for_each_entry(p, &sr->all_publ, all_publ) {
                if (p->scope != scope)
                        continue;
                if (p->port == exclude && p->node == self)
                        continue;
                tipc_dest_push(dsts, p->node, p->port);
                (*dstcnt)++;
                if (all)
                        continue;
                list_move_tail(&p->all_publ, &sr->all_publ);
                break;
        }
no_match:
        spin_unlock_bh(&sc->lock);
exit:
        rcu_read_unlock();
        return !list_empty(dsts);
}

void tipc_nametbl_mc_lookup(struct net *net, u32 type, u32 lower, u32 upper,
                            u32 scope, bool exact, struct list_head *dports)
{
        struct service_range *sr;
        struct tipc_service *sc;
        struct publication *p;

        rcu_read_lock();
        sc = tipc_service_find(net, type);
        if (!sc)
                goto exit;

        spin_lock_bh(&sc->lock);
        service_range_foreach_match(sr, sc, lower, upper) {
                list_for_each_entry(p, &sr->local_publ, local_publ) {
                        if (p->scope == scope || (!exact && p->scope < scope))
                                tipc_dest_push(dports, 0, p->port);
                }
        }
        spin_unlock_bh(&sc->lock);
exit:
        rcu_read_unlock();
}

/* tipc_nametbl_lookup_dst_nodes - find broadcast destination nodes
 * - Creates list of nodes that overlap the given multicast address
 * - Determines if any node local destinations overlap
 */
void tipc_nametbl_lookup_dst_nodes(struct net *net, u32 type, u32 lower,
                                   u32 upper, struct tipc_nlist *nodes)
{
        struct service_range *sr;
        struct tipc_service *sc;
        struct publication *p;

        rcu_read_lock();
        sc = tipc_service_find(net, type);
        if (!sc)
                goto exit;

        spin_lock_bh(&sc->lock);
        service_range_foreach_match(sr, sc, lower, upper) {
                list_for_each_entry(p, &sr->all_publ, all_publ) {
                        tipc_nlist_add(nodes, p->node);
                }
        }
        spin_unlock_bh(&sc->lock);
exit:
        rcu_read_unlock();
}

/* tipc_nametbl_build_group - build list of communication group members
 */
void tipc_nametbl_build_group(struct net *net, struct tipc_group *grp,
                              u32 type, u32 scope)
{
        struct service_range *sr;
        struct tipc_service *sc;
        struct publication *p;
        struct rb_node *n;

        rcu_read_lock();
        sc = tipc_service_find(net, type);
        if (!sc)
                goto exit;

        spin_lock_bh(&sc->lock);
        for (n = rb_first(&sc->ranges); n; n = rb_next(n)) {
                sr = container_of(n, struct service_range, tree_node);
                list_for_each_entry(p, &sr->all_publ, all_publ) {
                        if (p->scope != scope)
                                continue;
                        tipc_group_add_member(grp, p->node, p->port, p->lower);
                }
        }
        spin_unlock_bh(&sc->lock);
exit:
        rcu_read_unlock();
}

/* tipc_nametbl_publish - add service binding to name table
 */
struct publication *tipc_nametbl_publish(struct net *net, u32 type, u32 lower,
                                         u32 upper, u32 scope, u32 port,
                                         u32 key)
{
        struct name_table *nt = tipc_name_table(net);
        struct tipc_net *tn = tipc_net(net);
        struct publication *p = NULL;
        struct sk_buff *skb = NULL;
        u32 rc_dests;

        spin_lock_bh(&tn->nametbl_lock);

        if (nt->local_publ_count >= TIPC_MAX_PUBL) {
                pr_warn("Bind failed, max limit %u reached\n", TIPC_MAX_PUBL);
                goto exit;
        }

        p = tipc_nametbl_insert_publ(net, type, lower, upper, scope,
                                     tipc_own_addr(net), port, key);
        if (p) {
                nt->local_publ_count++;
                skb = tipc_named_publish(net, p);
        }
        rc_dests = nt->rc_dests;
exit:
        spin_unlock_bh(&tn->nametbl_lock);

        if (skb)
                tipc_node_broadcast(net, skb, rc_dests);
        return p;

}

/**
 * tipc_nametbl_withdraw - withdraw a service binding
 */
int tipc_nametbl_withdraw(struct net *net, u32 type, u32 lower,
                          u32 upper, u32 key)
{
        struct name_table *nt = tipc_name_table(net);
        struct tipc_net *tn = tipc_net(net);
        u32 self = tipc_own_addr(net);
        struct sk_buff *skb = NULL;
        struct publication *p;
        u32 rc_dests;

        spin_lock_bh(&tn->nametbl_lock);

        p = tipc_nametbl_remove_publ(net, type, lower, upper, self, key);
        if (p) {
                nt->local_publ_count--;
                skb = tipc_named_withdraw(net, p);
                list_del_init(&p->binding_sock);
                kfree_rcu(p, rcu);
        } else {
                pr_err("Failed to remove local publication {%u,%u,%u}/%u\n",
                       type, lower, upper, key);
        }
        rc_dests = nt->rc_dests;
        spin_unlock_bh(&tn->nametbl_lock);

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

/**
 * tipc_nametbl_subscribe - add a subscription object to the name table
 */
bool tipc_nametbl_subscribe(struct tipc_subscription *sub)
{
        struct name_table *nt = tipc_name_table(sub->net);
        struct tipc_net *tn = tipc_net(sub->net);
        struct tipc_subscr *s = &sub->evt.s;
        u32 type = tipc_sub_read(s, seq.type);
        struct tipc_service *sc;
        bool res = true;

        spin_lock_bh(&tn->nametbl_lock);
        sc = tipc_service_find(sub->net, type);
        if (!sc)
                sc = tipc_service_create(type, &nt->services[hash(type)]);
        if (sc) {
                spin_lock_bh(&sc->lock);
                tipc_service_subscribe(sc, sub);
                spin_unlock_bh(&sc->lock);
        } else {
                pr_warn("Failed to subscribe for {%u,%u,%u}\n", type,
                        tipc_sub_read(s, seq.lower),
                        tipc_sub_read(s, seq.upper));
                res = false;
        }
        spin_unlock_bh(&tn->nametbl_lock);
        return res;
}

/**
 * tipc_nametbl_unsubscribe - remove a subscription object from name table
 */
void tipc_nametbl_unsubscribe(struct tipc_subscription *sub)
{
        struct tipc_net *tn = tipc_net(sub->net);
        struct tipc_subscr *s = &sub->evt.s;
        u32 type = tipc_sub_read(s, seq.type);
        struct tipc_service *sc;

        spin_lock_bh(&tn->nametbl_lock);
        sc = tipc_service_find(sub->net, type);
        if (!sc)
                goto exit;

        spin_lock_bh(&sc->lock);
        list_del_init(&sub->service_list);
        tipc_sub_put(sub);

        /* Delete service item if no more publications and subscriptions */
        if (RB_EMPTY_ROOT(&sc->ranges) && list_empty(&sc->subscriptions)) {
                hlist_del_init_rcu(&sc->service_list);
                kfree_rcu(sc, rcu);
        }
        spin_unlock_bh(&sc->lock);
exit:
        spin_unlock_bh(&tn->nametbl_lock);
}

int tipc_nametbl_init(struct net *net)
{
        struct tipc_net *tn = tipc_net(net);
        struct name_table *nt;
        int i;

        nt = kzalloc(sizeof(*nt), GFP_KERNEL);
        if (!nt)
                return -ENOMEM;

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

        INIT_LIST_HEAD(&nt->node_scope);
        INIT_LIST_HEAD(&nt->cluster_scope);
        rwlock_init(&nt->cluster_scope_lock);
        tn->nametbl = nt;
        spin_lock_init(&tn->nametbl_lock);
        return 0;
}

/**
 *  tipc_service_delete - purge all publications for a service and delete it
 */
static void tipc_service_delete(struct net *net, struct tipc_service *sc)
{
        struct service_range *sr, *tmpr;
        struct publication *p, *tmp;

        spin_lock_bh(&sc->lock);
        rbtree_postorder_for_each_entry_safe(sr, tmpr, &sc->ranges, tree_node) {
                list_for_each_entry_safe(p, tmp, &sr->all_publ, all_publ) {
                        tipc_service_remove_publ(sr, p->node, p->key);
                        kfree_rcu(p, rcu);
                }
                rb_erase_augmented(&sr->tree_node, &sc->ranges, &sr_callbacks);
                kfree(sr);
        }
        hlist_del_init_rcu(&sc->service_list);
        spin_unlock_bh(&sc->lock);
        kfree_rcu(sc, rcu);
}

void tipc_nametbl_stop(struct net *net)
{
        struct name_table *nt = tipc_name_table(net);
        struct tipc_net *tn = tipc_net(net);
        struct hlist_head *service_head;
        struct tipc_service *service;
        u32 i;

        /* 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(&nt->services[i]))
                        continue;
                service_head = &nt->services[i];
                hlist_for_each_entry_rcu(service, service_head, service_list) {
                        tipc_service_delete(net, service);
                }
        }
        spin_unlock_bh(&tn->nametbl_lock);

        synchronize_net();
        kfree(nt);
}

static int __tipc_nl_add_nametable_publ(struct tipc_nl_msg *msg,
                                        struct tipc_service *service,
                                        struct service_range *sr,
                                        u32 *last_key)
{
        struct publication *p;
        struct nlattr *attrs;
        struct nlattr *b;
        void *hdr;

        if (*last_key) {
                list_for_each_entry(p, &sr->all_publ, all_publ)
                        if (p->key == *last_key)
                                break;
                if (p->key != *last_key)
                        return -EPIPE;
        } else {
                p = list_first_entry(&sr->all_publ,
                                     struct publication,
                                     all_publ);
        }

        list_for_each_entry_from(p, &sr->all_publ, all_publ) {
                *last_key = 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_noflag(msg->skb, TIPC_NLA_NAME_TABLE);
                if (!attrs)
                        goto msg_full;

                b = nla_nest_start_noflag(msg->skb, TIPC_NLA_NAME_TABLE_PUBL);
                if (!b)
                        goto attr_msg_full;

                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_TYPE, service->type))
                        goto publ_msg_full;
                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_LOWER, sr->lower))
                        goto publ_msg_full;
                if (nla_put_u32(msg->skb, TIPC_NLA_PUBL_UPPER, sr->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->port))
                        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, b);
                nla_nest_end(msg->skb, attrs);
                genlmsg_end(msg->skb, hdr);
        }
        *last_key = 0;

        return 0;

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

        return -EMSGSIZE;
}

static int __tipc_nl_service_range_list(struct tipc_nl_msg *msg,
                                        struct tipc_service *sc,
                                        u32 *last_lower, u32 *last_key)
{
        struct service_range *sr;
        struct rb_node *n;
        int err;

        for (n = rb_first(&sc->ranges); n; n = rb_next(n)) {
                sr = container_of(n, struct service_range, tree_node);
                if (sr->lower < *last_lower)
                        continue;
                err = __tipc_nl_add_nametable_publ(msg, sc, sr, last_key);
                if (err) {
                        *last_lower = sr->lower;
                        return err;
                }
        }
        *last_lower = 0;
        return 0;
}

static int tipc_nl_service_list(struct net *net, struct tipc_nl_msg *msg,
                                u32 *last_type, u32 *last_lower, u32 *last_key)
{
        struct tipc_net *tn = tipc_net(net);
        struct tipc_service *service = NULL;
        struct hlist_head *head;
        int err;
        int i;

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

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

                if (*last_type ||
                    (!i && *last_key && (*last_lower == *last_key))) {
                        service = tipc_service_find(net, *last_type);
                        if (!service)
                                return -EPIPE;
                } else {
                        hlist_for_each_entry_rcu(service, head, service_list)
                                break;
                        if (!service)
                                continue;
                }

                hlist_for_each_entry_from_rcu(service, service_list) {
                        spin_lock_bh(&service->lock);
                        err = __tipc_nl_service_range_list(msg, service,
                                                           last_lower,
                                                           last_key);

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

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

        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_service_list(net, &msg, &last_type,
                                   &last_lower, &last_key);
        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_key;
        cb->args[3] = done;

        return skb->len;
}

struct tipc_dest *tipc_dest_find(struct list_head *l, u32 node, u32 port)
{
        struct tipc_dest *dst;

        list_for_each_entry(dst, l, list) {
                if (dst->node == node && dst->port == port)
                        return dst;
        }
        return NULL;
}

bool tipc_dest_push(struct list_head *l, u32 node, u32 port)
{
        struct tipc_dest *dst;

        if (tipc_dest_find(l, node, port))
                return false;

        dst = kmalloc(sizeof(*dst), GFP_ATOMIC);
        if (unlikely(!dst))
                return false;
        dst->node = node;
        dst->port = port;
        list_add(&dst->list, l);
        return true;
}

bool tipc_dest_pop(struct list_head *l, u32 *node, u32 *port)
{
        struct tipc_dest *dst;

        if (list_empty(l))
                return false;
        dst = list_first_entry(l, typeof(*dst), list);
        if (port)
                *port = dst->port;
        if (node)
                *node = dst->node;
        list_del(&dst->list);
        kfree(dst);
        return true;
}

bool tipc_dest_del(struct list_head *l, u32 node, u32 port)
{
        struct tipc_dest *dst;

        dst = tipc_dest_find(l, node, port);
        if (!dst)
                return false;
        list_del(&dst->list);
        kfree(dst);
        return true;
}

void tipc_dest_list_purge(struct list_head *l)
{
        struct tipc_dest *dst, *tmp;

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

int tipc_dest_list_len(struct list_head *l)
{
        struct tipc_dest *dst;
        int i = 0;

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