/*
   * 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 <SteveW@ACM.org>
   *              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
  ",
  		       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 pid, 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;

  	unsigned char *b = skb_tail_pointer(skb);

  
  	nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*rtm), flags);
  	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;

  	RTA_PUT_U32(skb, RTA_TABLE, tb_id);

  	rtm->rtm_flags = fi->fib_flags;
  	rtm->rtm_scope = scope;

  	rtm->rtm_type  = type;

  	if (rtm->rtm_dst_len)
  		RTA_PUT(skb, RTA_DST, 2, dst);
  	rtm->rtm_protocol = fi->fib_protocol;
  	if (fi->fib_priority)
  		RTA_PUT(skb, RTA_PRIORITY, 4, &fi->fib_priority);

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

  	if (fi->fib_nhs == 1) {
  		if (fi->fib_nh->nh_gw)
  			RTA_PUT(skb, RTA_GATEWAY, 2, &fi->fib_nh->nh_gw);
  		if (fi->fib_nh->nh_oif)
  			RTA_PUT(skb, RTA_OIF, sizeof(int), &fi->fib_nh->nh_oif);
  	}
  	if (fi->fib_nhs > 1) {
  		struct rtnexthop *nhp;
  		struct rtattr *mp_head;
  		if (skb_tailroom(skb) <= RTA_SPACE(0))
  			goto rtattr_failure;
  		mp_head = (struct rtattr *)skb_put(skb, RTA_SPACE(0));
  
  		for_nexthops(fi) {
  			if (skb_tailroom(skb) < RTA_ALIGN(RTA_ALIGN(sizeof(*nhp)) + 4))
  				goto rtattr_failure;
  			nhp = (struct rtnexthop *)skb_put(skb, RTA_ALIGN(sizeof(*nhp)));
  			nhp->rtnh_flags = nh->nh_flags & 0xFF;
  			nhp->rtnh_hops = nh->nh_weight - 1;
  			nhp->rtnh_ifindex = nh->nh_oif;
  			if (nh->nh_gw)
  				RTA_PUT(skb, RTA_GATEWAY, 2, &nh->nh_gw);

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

  		} endfor_nexthops(fi);
  		mp_head->rta_type = RTA_MULTIPATH;

  		mp_head->rta_len = skb_tail_pointer(skb) - (u8 *)mp_head;

  	}

  	nlh->nlmsg_len = skb_tail_pointer(skb) - b;

  	return skb->len;

  
  
  nlmsg_failure:
  rtattr_failure:

  	nlmsg_trim(skb, b);

  	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 pid = req ? req->pid : 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, pid, 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, pid, 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).pid,

  				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_ratelimit()) {
  		printk(KERN_DEBUG "DECnet: BUG! Attempt to create routing table from interrupt
  ");
  		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);

  }