dn_table.c

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/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Routing Forwarding Information Base (Routing Tables)
 *
 * Author:      Steve Whitehouse <[email protected]>
 *              Mostly copied from the IPv4 routing code
 *
 *
 * Changes:
 *
 */
#include <linux/string.h>
#include <linux/net.h>
#include <linux/socket.h>
#include <linux/slab.h>
#include <linux/sockios.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/proc_fs.h>
#include <linux/netdevice.h>
#include <linux/timer.h>
#include <linux/spinlock.h>
#include <linux/atomic.h>
#include <asm/uaccess.h>
#include <linux/route.h> /* RTF_xxx */
#include <net/neighbour.h>
#include <net/netlink.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/fib_rules.h>
#include <net/dn.h>
#include <net/dn_route.h>
#include <net/dn_fib.h>
#include <net/dn_neigh.h>
#include <net/dn_dev.h>

struct dn_zone
{
    struct dn_zone      *dz_next;
    struct dn_fib_node  **dz_hash;
    int         dz_nent;
    int         dz_divisor;
    u32         dz_hashmask;
#define DZ_HASHMASK(dz) ((dz)->dz_hashmask)
    int         dz_order;
    __le16          dz_mask;
#define DZ_MASK(dz) ((dz)->dz_mask)
};

struct dn_hash
{
    struct dn_zone  *dh_zones[17];
    struct dn_zone  *dh_zone_list;
};

#define dz_key_0(key)       ((key).datum = 0)

#define for_nexthops(fi) { int nhsel; const struct dn_fib_nh *nh;\
    for(nhsel = 0, nh = (fi)->fib_nh; nhsel < (fi)->fib_nhs; nh++, nhsel++)

#define endfor_nexthops(fi) }

#define DN_MAX_DIVISOR 1024
#define DN_S_ZOMBIE 1
#define DN_S_ACCESSED 2

#define DN_FIB_SCAN(f, fp) \
for( ; ((f) = *(fp)) != NULL; (fp) = &(f)->fn_next)

#define DN_FIB_SCAN_KEY(f, fp, key) \
for( ; ((f) = *(fp)) != NULL && dn_key_eq((f)->fn_key, (key)); (fp) = &(f)->fn_next)

#define RT_TABLE_MIN 1
#define DN_FIB_TABLE_HASHSZ 256
static struct hlist_head dn_fib_table_hash[DN_FIB_TABLE_HASHSZ];
static DEFINE_RWLOCK(dn_fib_tables_lock);

static struct kmem_cache *dn_hash_kmem __read_mostly;
static int dn_fib_hash_zombies;

static inline dn_fib_idx_t dn_hash(dn_fib_key_t key, struct dn_zone *dz)
{
    u16 h = le16_to_cpu(key.datum)>>(16 - dz->dz_order);
    h ^= (h >> 10);
    h ^= (h >> 6);
    h &= DZ_HASHMASK(dz);
    return *(dn_fib_idx_t *)&h;
}

static inline dn_fib_key_t dz_key(__le16 dst, struct dn_zone *dz)
{
    dn_fib_key_t k;
    k.datum = dst & DZ_MASK(dz);
    return k;
}

static inline struct dn_fib_node **dn_chain_p(dn_fib_key_t key, struct dn_zone *dz)
{
    return &dz->dz_hash[dn_hash(key, dz).datum];
}

static inline struct dn_fib_node *dz_chain(dn_fib_key_t key, struct dn_zone *dz)
{
    return dz->dz_hash[dn_hash(key, dz).datum];
}

static inline int dn_key_eq(dn_fib_key_t a, dn_fib_key_t b)
{
    return a.datum == b.datum;
}

static inline int dn_key_leq(dn_fib_key_t a, dn_fib_key_t b)
{
    return a.datum <= b.datum;
}

static inline void dn_rebuild_zone(struct dn_zone *dz,
                   struct dn_fib_node **old_ht,
                   int old_divisor)
{
    struct dn_fib_node *f, **fp, *next;
    int i;

    for(i = 0; i < old_divisor; i++) {
        for(f = old_ht[i]; f; f = next) {
            next = f->fn_next;
            for(fp = dn_chain_p(f->fn_key, dz);
                *fp && dn_key_leq((*fp)->fn_key, f->fn_key);
                fp = &(*fp)->fn_next)
                /* NOTHING */;
            f->fn_next = *fp;
            *fp = f;
        }
    }
}

static void dn_rehash_zone(struct dn_zone *dz)
{
    struct dn_fib_node **ht, **old_ht;
    int old_divisor, new_divisor;
    u32 new_hashmask;

    old_divisor = dz->dz_divisor;

    switch (old_divisor) {
    case 16:
        new_divisor = 256;
        new_hashmask = 0xFF;
        break;
    default:
        printk(KERN_DEBUG "DECnet: dn_rehash_zone: BUG! %d\n",
               old_divisor);
    case 256:
        new_divisor = 1024;
        new_hashmask = 0x3FF;
        break;
    }

    ht = kcalloc(new_divisor, sizeof(struct dn_fib_node*), GFP_KERNEL);
    if (ht == NULL)
        return;

    write_lock_bh(&dn_fib_tables_lock);
    old_ht = dz->dz_hash;
    dz->dz_hash = ht;
    dz->dz_hashmask = new_hashmask;
    dz->dz_divisor = new_divisor;
    dn_rebuild_zone(dz, old_ht, old_divisor);
    write_unlock_bh(&dn_fib_tables_lock);
    kfree(old_ht);
}

static void dn_free_node(struct dn_fib_node *f)
{
    dn_fib_release_info(DN_FIB_INFO(f));
    kmem_cache_free(dn_hash_kmem, f);
}


static struct dn_zone *dn_new_zone(struct dn_hash *table, int z)
{
    int i;
    struct dn_zone *dz = kzalloc(sizeof(struct dn_zone), GFP_KERNEL);
    if (!dz)
        return NULL;

    if (z) {
        dz->dz_divisor = 16;
        dz->dz_hashmask = 0x0F;
    } else {
        dz->dz_divisor = 1;
        dz->dz_hashmask = 0;
    }

    dz->dz_hash = kcalloc(dz->dz_divisor, sizeof(struct dn_fib_node *), GFP_KERNEL);
    if (!dz->dz_hash) {
        kfree(dz);
        return NULL;
    }

    dz->dz_order = z;
    dz->dz_mask = dnet_make_mask(z);

    for(i = z + 1; i <= 16; i++)
        if (table->dh_zones[i])
            break;

    write_lock_bh(&dn_fib_tables_lock);
    if (i>16) {
        dz->dz_next = table->dh_zone_list;
        table->dh_zone_list = dz;
    } else {
        dz->dz_next = table->dh_zones[i]->dz_next;
        table->dh_zones[i]->dz_next = dz;
    }
    table->dh_zones[z] = dz;
    write_unlock_bh(&dn_fib_tables_lock);
    return dz;
}


static int dn_fib_nh_match(struct rtmsg *r, struct nlmsghdr *nlh, struct dn_kern_rta *rta, struct dn_fib_info *fi)
{
    struct rtnexthop *nhp;
    int nhlen;

    if (rta->rta_priority && *rta->rta_priority != fi->fib_priority)
        return 1;

    if (rta->rta_oif || rta->rta_gw) {
        if ((!rta->rta_oif || *rta->rta_oif == fi->fib_nh->nh_oif) &&
            (!rta->rta_gw  || memcmp(rta->rta_gw, &fi->fib_nh->nh_gw, 2) == 0))
            return 0;
        return 1;
    }

    if (rta->rta_mp == NULL)
        return 0;

    nhp = RTA_DATA(rta->rta_mp);
    nhlen = RTA_PAYLOAD(rta->rta_mp);

    for_nexthops(fi) {
        int attrlen = nhlen - sizeof(struct rtnexthop);
        __le16 gw;

        if (attrlen < 0 || (nhlen -= nhp->rtnh_len) < 0)
            return -EINVAL;
        if (nhp->rtnh_ifindex && nhp->rtnh_ifindex != nh->nh_oif)
            return 1;
        if (attrlen) {
            gw = dn_fib_get_attr16(RTNH_DATA(nhp), attrlen, RTA_GATEWAY);

            if (gw && gw != nh->nh_gw)
                return 1;
        }
        nhp = RTNH_NEXT(nhp);
    } endfor_nexthops(fi);

    return 0;
}

static inline size_t dn_fib_nlmsg_size(struct dn_fib_info *fi)
{
    size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
             + nla_total_size(4) /* RTA_TABLE */
             + nla_total_size(2) /* RTA_DST */
             + nla_total_size(4); /* RTA_PRIORITY */

    /* space for nested metrics */
    payload += nla_total_size((RTAX_MAX * nla_total_size(4)));

    if (fi->fib_nhs) {
        /* Also handles the special case fib_nhs == 1 */

        /* each nexthop is packed in an attribute */
        size_t nhsize = nla_total_size(sizeof(struct rtnexthop));

        /* may contain a gateway attribute */
        nhsize += nla_total_size(4);

        /* all nexthops are packed in a nested attribute */
        payload += nla_total_size(fi->fib_nhs * nhsize);
    }

    return payload;
}

static int dn_fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
            u32 tb_id, u8 type, u8 scope, void *dst, int dst_len,
            struct dn_fib_info *fi, unsigned int flags)
{
    struct rtmsg *rtm;
    struct nlmsghdr *nlh;

    nlh = nlmsg_put(skb, portid, seq, event, sizeof(*rtm), flags);
    if (!nlh)
        return -EMSGSIZE;

    rtm = nlmsg_data(nlh);
    rtm->rtm_family = AF_DECnet;
    rtm->rtm_dst_len = dst_len;
    rtm->rtm_src_len = 0;
    rtm->rtm_tos = 0;
    rtm->rtm_table = tb_id;
    rtm->rtm_flags = fi->fib_flags;
    rtm->rtm_scope = scope;
    rtm->rtm_type  = type;
    rtm->rtm_protocol = fi->fib_protocol;

    if (nla_put_u32(skb, RTA_TABLE, tb_id) < 0)
        goto errout;

    if (rtm->rtm_dst_len &&
        nla_put(skb, RTA_DST, 2, dst) < 0)
        goto errout;

    if (fi->fib_priority &&
        nla_put_u32(skb, RTA_PRIORITY, fi->fib_priority) < 0)
        goto errout;

    if (rtnetlink_put_metrics(skb, fi->fib_metrics) < 0)
        goto errout;

    if (fi->fib_nhs == 1) {
        if (fi->fib_nh->nh_gw &&
            nla_put_le16(skb, RTA_GATEWAY, fi->fib_nh->nh_gw) < 0)
            goto errout;

        if (fi->fib_nh->nh_oif &&
            nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif) < 0)
            goto errout;
    }

    if (fi->fib_nhs > 1) {
        struct rtnexthop *nhp;
        struct nlattr *mp_head;

        if (!(mp_head = nla_nest_start(skb, RTA_MULTIPATH)))
            goto errout;

        for_nexthops(fi) {
            if (!(nhp = nla_reserve_nohdr(skb, sizeof(*nhp))))
                goto errout;

            nhp->rtnh_flags = nh->nh_flags & 0xFF;
            nhp->rtnh_hops = nh->nh_weight - 1;
            nhp->rtnh_ifindex = nh->nh_oif;

            if (nh->nh_gw &&
                nla_put_le16(skb, RTA_GATEWAY, nh->nh_gw) < 0)
                goto errout;

            nhp->rtnh_len = skb_tail_pointer(skb) - (unsigned char *)nhp;
        } endfor_nexthops(fi);

        nla_nest_end(skb, mp_head);
    }

    return nlmsg_end(skb, nlh);

errout:
    nlmsg_cancel(skb, nlh);
    return -EMSGSIZE;
}


static void dn_rtmsg_fib(int event, struct dn_fib_node *f, int z, u32 tb_id,
            struct nlmsghdr *nlh, struct netlink_skb_parms *req)
{
    struct sk_buff *skb;
    u32 portid = req ? req->portid : 0;
    int err = -ENOBUFS;

    skb = nlmsg_new(dn_fib_nlmsg_size(DN_FIB_INFO(f)), GFP_KERNEL);
    if (skb == NULL)
        goto errout;

    err = dn_fib_dump_info(skb, portid, nlh->nlmsg_seq, event, tb_id,
                   f->fn_type, f->fn_scope, &f->fn_key, z,
                   DN_FIB_INFO(f), 0);
    if (err < 0) {
        /* -EMSGSIZE implies BUG in dn_fib_nlmsg_size() */
        WARN_ON(err == -EMSGSIZE);
        kfree_skb(skb);
        goto errout;
    }
    rtnl_notify(skb, &init_net, portid, RTNLGRP_DECnet_ROUTE, nlh, GFP_KERNEL);
    return;
errout:
    if (err < 0)
        rtnl_set_sk_err(&init_net, RTNLGRP_DECnet_ROUTE, err);
}

static __inline__ int dn_hash_dump_bucket(struct sk_buff *skb,
                struct netlink_callback *cb,
                struct dn_fib_table *tb,
                struct dn_zone *dz,
                struct dn_fib_node *f)
{
    int i, s_i;

    s_i = cb->args[4];
    for(i = 0; f; i++, f = f->fn_next) {
        if (i < s_i)
            continue;
        if (f->fn_state & DN_S_ZOMBIE)
            continue;
        if (dn_fib_dump_info(skb, NETLINK_CB(cb->skb).portid,
                cb->nlh->nlmsg_seq,
                RTM_NEWROUTE,
                tb->n,
                (f->fn_state & DN_S_ZOMBIE) ? 0 : f->fn_type,
                f->fn_scope, &f->fn_key, dz->dz_order,
                f->fn_info, NLM_F_MULTI) < 0) {
            cb->args[4] = i;
            return -1;
        }
    }
    cb->args[4] = i;
    return skb->len;
}

static __inline__ int dn_hash_dump_zone(struct sk_buff *skb,
                struct netlink_callback *cb,
                struct dn_fib_table *tb,
                struct dn_zone *dz)
{
    int h, s_h;

    s_h = cb->args[3];
    for(h = 0; h < dz->dz_divisor; h++) {
        if (h < s_h)
            continue;
        if (h > s_h)
            memset(&cb->args[4], 0, sizeof(cb->args) - 4*sizeof(cb->args[0]));
        if (dz->dz_hash == NULL || dz->dz_hash[h] == NULL)
            continue;
        if (dn_hash_dump_bucket(skb, cb, tb, dz, dz->dz_hash[h]) < 0) {
            cb->args[3] = h;
            return -1;
        }
    }
    cb->args[3] = h;
    return skb->len;
}

static int dn_fib_table_dump(struct dn_fib_table *tb, struct sk_buff *skb,
                struct netlink_callback *cb)
{
    int m, s_m;
    struct dn_zone *dz;
    struct dn_hash *table = (struct dn_hash *)tb->data;

    s_m = cb->args[2];
    read_lock(&dn_fib_tables_lock);
    for(dz = table->dh_zone_list, m = 0; dz; dz = dz->dz_next, m++) {
        if (m < s_m)
            continue;
        if (m > s_m)
            memset(&cb->args[3], 0, sizeof(cb->args) - 3*sizeof(cb->args[0]));

        if (dn_hash_dump_zone(skb, cb, tb, dz) < 0) {
            cb->args[2] = m;
            read_unlock(&dn_fib_tables_lock);
            return -1;
        }
    }
    read_unlock(&dn_fib_tables_lock);
    cb->args[2] = m;

    return skb->len;
}

int dn_fib_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
    struct net *net = sock_net(skb->sk);
    unsigned int h, s_h;
    unsigned int e = 0, s_e;
    struct dn_fib_table *tb;
    struct hlist_node *node;
    int dumped = 0;

    if (!net_eq(net, &init_net))
        return 0;

    if (NLMSG_PAYLOAD(cb->nlh, 0) >= sizeof(struct rtmsg) &&
        ((struct rtmsg *)nlmsg_data(cb->nlh))->rtm_flags&RTM_F_CLONED)
            return dn_cache_dump(skb, cb);

    s_h = cb->args[0];
    s_e = cb->args[1];

    for (h = s_h; h < DN_FIB_TABLE_HASHSZ; h++, s_h = 0) {
        e = 0;
        hlist_for_each_entry(tb, node, &dn_fib_table_hash[h], hlist) {
            if (e < s_e)
                goto next;
            if (dumped)
                memset(&cb->args[2], 0, sizeof(cb->args) -
                         2 * sizeof(cb->args[0]));
            if (tb->dump(tb, skb, cb) < 0)
                goto out;
            dumped = 1;
next:
            e++;
        }
    }
out:
    cb->args[1] = e;
    cb->args[0] = h;

    return skb->len;
}

static int dn_fib_table_insert(struct dn_fib_table *tb, struct rtmsg *r, struct dn_kern_rta *rta, struct nlmsghdr *n, struct netlink_skb_parms *req)
{
    struct dn_hash *table = (struct dn_hash *)tb->data;
    struct dn_fib_node *new_f, *f, **fp, **del_fp;
    struct dn_zone *dz;
    struct dn_fib_info *fi;
    int z = r->rtm_dst_len;
    int type = r->rtm_type;
    dn_fib_key_t key;
    int err;

    if (z > 16)
        return -EINVAL;

    dz = table->dh_zones[z];
    if (!dz && !(dz = dn_new_zone(table, z)))
        return -ENOBUFS;

    dz_key_0(key);
    if (rta->rta_dst) {
        __le16 dst;
        memcpy(&dst, rta->rta_dst, 2);
        if (dst & ~DZ_MASK(dz))
            return -EINVAL;
        key = dz_key(dst, dz);
    }

    if ((fi = dn_fib_create_info(r, rta, n, &err)) == NULL)
        return err;

    if (dz->dz_nent > (dz->dz_divisor << 2) &&
            dz->dz_divisor > DN_MAX_DIVISOR &&
            (z==16 || (1<<z) > dz->dz_divisor))
        dn_rehash_zone(dz);

    fp = dn_chain_p(key, dz);

    DN_FIB_SCAN(f, fp) {
        if (dn_key_leq(key, f->fn_key))
            break;
    }

    del_fp = NULL;

    if (f && (f->fn_state & DN_S_ZOMBIE) &&
            dn_key_eq(f->fn_key, key)) {
        del_fp = fp;
        fp = &f->fn_next;
        f = *fp;
        goto create;
    }

    DN_FIB_SCAN_KEY(f, fp, key) {
        if (fi->fib_priority <= DN_FIB_INFO(f)->fib_priority)
            break;
    }

    if (f && dn_key_eq(f->fn_key, key) &&
            fi->fib_priority == DN_FIB_INFO(f)->fib_priority) {
        struct dn_fib_node **ins_fp;

        err = -EEXIST;
        if (n->nlmsg_flags & NLM_F_EXCL)
            goto out;

        if (n->nlmsg_flags & NLM_F_REPLACE) {
            del_fp = fp;
            fp = &f->fn_next;
            f = *fp;
            goto replace;
        }

        ins_fp = fp;
        err = -EEXIST;

        DN_FIB_SCAN_KEY(f, fp, key) {
            if (fi->fib_priority != DN_FIB_INFO(f)->fib_priority)
                break;
            if (f->fn_type == type &&
                f->fn_scope == r->rtm_scope &&
                DN_FIB_INFO(f) == fi)
                goto out;
        }

        if (!(n->nlmsg_flags & NLM_F_APPEND)) {
            fp = ins_fp;
            f = *fp;
        }
    }

create:
    err = -ENOENT;
    if (!(n->nlmsg_flags & NLM_F_CREATE))
        goto out;

replace:
    err = -ENOBUFS;
    new_f = kmem_cache_zalloc(dn_hash_kmem, GFP_KERNEL);
    if (new_f == NULL)
        goto out;

    new_f->fn_key = key;
    new_f->fn_type = type;
    new_f->fn_scope = r->rtm_scope;
    DN_FIB_INFO(new_f) = fi;

    new_f->fn_next = f;
    write_lock_bh(&dn_fib_tables_lock);
    *fp = new_f;
    write_unlock_bh(&dn_fib_tables_lock);
    dz->dz_nent++;

    if (del_fp) {
        f = *del_fp;
        write_lock_bh(&dn_fib_tables_lock);
        *del_fp = f->fn_next;
        write_unlock_bh(&dn_fib_tables_lock);

        if (!(f->fn_state & DN_S_ZOMBIE))
            dn_rtmsg_fib(RTM_DELROUTE, f, z, tb->n, n, req);
        if (f->fn_state & DN_S_ACCESSED)
            dn_rt_cache_flush(-1);
        dn_free_node(f);
        dz->dz_nent--;
    } else {
        dn_rt_cache_flush(-1);
    }

    dn_rtmsg_fib(RTM_NEWROUTE, new_f, z, tb->n, n, req);

    return 0;
out:
    dn_fib_release_info(fi);
    return err;
}


static int dn_fib_table_delete(struct dn_fib_table *tb, struct rtmsg *r, struct dn_kern_rta *rta, struct nlmsghdr *n, struct netlink_skb_parms *req)
{
    struct dn_hash *table = (struct dn_hash*)tb->data;
    struct dn_fib_node **fp, **del_fp, *f;
    int z = r->rtm_dst_len;
    struct dn_zone *dz;
    dn_fib_key_t key;
    int matched;


    if (z > 16)
        return -EINVAL;

    if ((dz = table->dh_zones[z]) == NULL)
        return -ESRCH;

    dz_key_0(key);
    if (rta->rta_dst) {
        __le16 dst;
        memcpy(&dst, rta->rta_dst, 2);
        if (dst & ~DZ_MASK(dz))
            return -EINVAL;
        key = dz_key(dst, dz);
    }

    fp = dn_chain_p(key, dz);

    DN_FIB_SCAN(f, fp) {
        if (dn_key_eq(f->fn_key, key))
            break;
        if (dn_key_leq(key, f->fn_key))
            return -ESRCH;
    }

    matched = 0;
    del_fp = NULL;
    DN_FIB_SCAN_KEY(f, fp, key) {
        struct dn_fib_info *fi = DN_FIB_INFO(f);

        if (f->fn_state & DN_S_ZOMBIE)
            return -ESRCH;

        matched++;

        if (del_fp == NULL &&
                (!r->rtm_type || f->fn_type == r->rtm_type) &&
                (r->rtm_scope == RT_SCOPE_NOWHERE || f->fn_scope == r->rtm_scope) &&
                (!r->rtm_protocol ||
                    fi->fib_protocol == r->rtm_protocol) &&
                dn_fib_nh_match(r, n, rta, fi) == 0)
            del_fp = fp;
    }

    if (del_fp) {
        f = *del_fp;
        dn_rtmsg_fib(RTM_DELROUTE, f, z, tb->n, n, req);

        if (matched != 1) {
            write_lock_bh(&dn_fib_tables_lock);
            *del_fp = f->fn_next;
            write_unlock_bh(&dn_fib_tables_lock);

            if (f->fn_state & DN_S_ACCESSED)
                dn_rt_cache_flush(-1);
            dn_free_node(f);
            dz->dz_nent--;
        } else {
            f->fn_state |= DN_S_ZOMBIE;
            if (f->fn_state & DN_S_ACCESSED) {
                f->fn_state &= ~DN_S_ACCESSED;
                dn_rt_cache_flush(-1);
            }
            if (++dn_fib_hash_zombies > 128)
                dn_fib_flush();
        }

        return 0;
    }

    return -ESRCH;
}

static inline int dn_flush_list(struct dn_fib_node **fp, int z, struct dn_hash *table)
{
    int found = 0;
    struct dn_fib_node *f;

    while((f = *fp) != NULL) {
        struct dn_fib_info *fi = DN_FIB_INFO(f);

        if (fi && ((f->fn_state & DN_S_ZOMBIE) || (fi->fib_flags & RTNH_F_DEAD))) {
            write_lock_bh(&dn_fib_tables_lock);
            *fp = f->fn_next;
            write_unlock_bh(&dn_fib_tables_lock);

            dn_free_node(f);
            found++;
            continue;
        }
        fp = &f->fn_next;
    }

    return found;
}

static int dn_fib_table_flush(struct dn_fib_table *tb)
{
    struct dn_hash *table = (struct dn_hash *)tb->data;
    struct dn_zone *dz;
    int found = 0;

    dn_fib_hash_zombies = 0;
    for(dz = table->dh_zone_list; dz; dz = dz->dz_next) {
        int i;
        int tmp = 0;
        for(i = dz->dz_divisor-1; i >= 0; i--)
            tmp += dn_flush_list(&dz->dz_hash[i], dz->dz_order, table);
        dz->dz_nent -= tmp;
        found += tmp;
    }

    return found;
}

static int dn_fib_table_lookup(struct dn_fib_table *tb, const struct flowidn *flp, struct dn_fib_res *res)
{
    int err;
    struct dn_zone *dz;
    struct dn_hash *t = (struct dn_hash *)tb->data;

    read_lock(&dn_fib_tables_lock);
    for(dz = t->dh_zone_list; dz; dz = dz->dz_next) {
        struct dn_fib_node *f;
        dn_fib_key_t k = dz_key(flp->daddr, dz);

        for(f = dz_chain(k, dz); f; f = f->fn_next) {
            if (!dn_key_eq(k, f->fn_key)) {
                if (dn_key_leq(k, f->fn_key))
                    break;
                else
                    continue;
            }

            f->fn_state |= DN_S_ACCESSED;

            if (f->fn_state&DN_S_ZOMBIE)
                continue;

            if (f->fn_scope < flp->flowidn_scope)
                continue;

            err = dn_fib_semantic_match(f->fn_type, DN_FIB_INFO(f), flp, res);

            if (err == 0) {
                res->type = f->fn_type;
                res->scope = f->fn_scope;
                res->prefixlen = dz->dz_order;
                goto out;
            }
            if (err < 0)
                goto out;
        }
    }
    err = 1;
out:
    read_unlock(&dn_fib_tables_lock);
    return err;
}


struct dn_fib_table *dn_fib_get_table(u32 n, int create)
{
    struct dn_fib_table *t;
    struct hlist_node *node;
    unsigned int h;

    if (n < RT_TABLE_MIN)
        return NULL;

    if (n > RT_TABLE_MAX)
        return NULL;

    h = n & (DN_FIB_TABLE_HASHSZ - 1);
    rcu_read_lock();
    hlist_for_each_entry_rcu(t, node, &dn_fib_table_hash[h], hlist) {
        if (t->n == n) {
            rcu_read_unlock();
            return t;
        }
    }
    rcu_read_unlock();

    if (!create)
        return NULL;

    if (in_interrupt()) {
        net_dbg_ratelimited("DECnet: BUG! Attempt to create routing table from interrupt\n");
        return NULL;
    }

    t = kzalloc(sizeof(struct dn_fib_table) + sizeof(struct dn_hash),
            GFP_KERNEL);
    if (t == NULL)
        return NULL;

    t->n = n;
    t->insert = dn_fib_table_insert;
    t->delete = dn_fib_table_delete;
    t->lookup = dn_fib_table_lookup;
    t->flush  = dn_fib_table_flush;
    t->dump = dn_fib_table_dump;
    hlist_add_head_rcu(&t->hlist, &dn_fib_table_hash[h]);

    return t;
}

struct dn_fib_table *dn_fib_empty_table(void)
{
    u32 id;

    for(id = RT_TABLE_MIN; id <= RT_TABLE_MAX; id++)
        if (dn_fib_get_table(id, 0) == NULL)
            return dn_fib_get_table(id, 1);
    return NULL;
}

void dn_fib_flush(void)
{
    int flushed = 0;
    struct dn_fib_table *tb;
    struct hlist_node *node;
    unsigned int h;

    for (h = 0; h < DN_FIB_TABLE_HASHSZ; h++) {
        hlist_for_each_entry(tb, node, &dn_fib_table_hash[h], hlist)
            flushed += tb->flush(tb);
    }

    if (flushed)
        dn_rt_cache_flush(-1);
}

void __init dn_fib_table_init(void)
{
    dn_hash_kmem = kmem_cache_create("dn_fib_info_cache",
                    sizeof(struct dn_fib_info),
                    0, SLAB_HWCACHE_ALIGN,
                    NULL);
}

void __exit dn_fib_table_cleanup(void)
{
    struct dn_fib_table *t;
    struct hlist_node *node, *next;
    unsigned int h;

    write_lock(&dn_fib_tables_lock);
    for (h = 0; h < DN_FIB_TABLE_HASHSZ; h++) {
        hlist_for_each_entry_safe(t, node, next, &dn_fib_table_hash[h],
                      hlist) {
            hlist_del(&t->hlist);
            kfree(t);
        }
    }
    write_unlock(&dn_fib_tables_lock);
}