neigh: remove dynamic neigh table registration support

Currently there are only three neigh tables in the whole kernel:
arp table, ndisc table and decnet neigh table. What's more,
we don't support registering multiple tables per family.
Therefore we can just make these tables statically built-in.

Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index dedfb18..eb070b3 100644 (file)
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -220,6 +220,13 @@ struct neigh_table {
        struct pneigh_entry     **phash_buckets;
 };
 
+enum {
+       NEIGH_ARP_TABLE = 0,
+       NEIGH_ND_TABLE = 1,
+       NEIGH_DN_TABLE = 2,
+       NEIGH_NR_TABLES,
+};
+
 static inline int neigh_parms_family(struct neigh_parms *p)
 {
        return p->tbl->family;
@@ -240,8 +247,8 @@ static inline void *neighbour_priv(const struct neighbour *n)
 #define NEIGH_UPDATE_F_ISROUTER                        0x40000000
 #define NEIGH_UPDATE_F_ADMIN                   0x80000000
 
-void neigh_table_init(struct neigh_table *tbl);
-int neigh_table_clear(struct neigh_table *tbl);
+void neigh_table_init(int index, struct neigh_table *tbl);
+int neigh_table_clear(int index, struct neigh_table *tbl);
 struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey,
                               struct net_device *dev);
 struct neighbour *neigh_lookup_nodev(struct neigh_table *tbl, struct net *net,

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index edd0411..8e38f17 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -56,7 +56,6 @@ static void __neigh_notify(struct neighbour *n, int type, int flags);
 static void neigh_update_notify(struct neighbour *neigh);
 static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
 
-static struct neigh_table *neigh_tables;
 #ifdef CONFIG_PROC_FS
 static const struct file_operations neigh_stat_seq_fops;
 #endif
@@ -87,13 +86,8 @@ static const struct file_operations neigh_stat_seq_fops;
    the most complicated procedure, which we allow is dev->hard_header.
    It is supposed, that dev->hard_header is simplistic and does
    not make callbacks to neighbour tables.
-
-   The last lock is neigh_tbl_lock. It is pure SMP lock, protecting
-   list of neighbour tables. This list is used only in process context,
  */
 
-static DEFINE_RWLOCK(neigh_tbl_lock);
-
 static int neigh_blackhole(struct neighbour *neigh, struct sk_buff *skb)
 {
        kfree_skb(skb);
@@ -1520,7 +1514,9 @@ static void neigh_parms_destroy(struct neigh_parms *parms)
 
 static struct lock_class_key neigh_table_proxy_queue_class;
 
-static void neigh_table_init_no_netlink(struct neigh_table *tbl)
+static struct neigh_table *neigh_tables[NEIGH_NR_TABLES] __read_mostly;
+
+void neigh_table_init(int index, struct neigh_table *tbl)
 {
        unsigned long now = jiffies;
        unsigned long phsize;
@@ -1566,34 +1562,14 @@ static void neigh_table_init_no_netlink(struct neigh_table *tbl)
 
        tbl->last_flush = now;
        tbl->last_rand  = now + tbl->parms.reachable_time * 20;
-}
-
-void neigh_table_init(struct neigh_table *tbl)
-{
-       struct neigh_table *tmp;
 
-       neigh_table_init_no_netlink(tbl);
-       write_lock(&neigh_tbl_lock);
-       for (tmp = neigh_tables; tmp; tmp = tmp->next) {
-               if (tmp->family == tbl->family)
-                       break;
-       }
-       tbl->next       = neigh_tables;
-       neigh_tables    = tbl;
-       write_unlock(&neigh_tbl_lock);
-
-       if (unlikely(tmp)) {
-               pr_err("Registering multiple tables for family %d\n",
-                      tbl->family);
-               dump_stack();
-       }
+       neigh_tables[index] = tbl;
 }
 EXPORT_SYMBOL(neigh_table_init);
 
-int neigh_table_clear(struct neigh_table *tbl)
+int neigh_table_clear(int index, struct neigh_table *tbl)
 {
-       struct neigh_table **tp;
-
+       neigh_tables[index] = NULL;
        /* It is not clean... Fix it to unload IPv6 module safely */
        cancel_delayed_work_sync(&tbl->gc_work);
        del_timer_sync(&tbl->proxy_timer);
@@ -1601,14 +1577,6 @@ int neigh_table_clear(struct neigh_table *tbl)
        neigh_ifdown(tbl, NULL);
        if (atomic_read(&tbl->entries))
                pr_crit("neighbour leakage\n");
-       write_lock(&neigh_tbl_lock);
-       for (tp = &neigh_tables; *tp; tp = &(*tp)->next) {
-               if (*tp == tbl) {
-                       *tp = tbl->next;
-                       break;
-               }
-       }
-       write_unlock(&neigh_tbl_lock);
 
        call_rcu(&rcu_dereference_protected(tbl->nht, 1)->rcu,
                 neigh_hash_free_rcu);
@@ -1626,12 +1594,32 @@ int neigh_table_clear(struct neigh_table *tbl)
 }
 EXPORT_SYMBOL(neigh_table_clear);
 
+static struct neigh_table *neigh_find_table(int family)
+{
+       struct neigh_table *tbl = NULL;
+
+       switch (family) {
+       case AF_INET:
+               tbl = neigh_tables[NEIGH_ARP_TABLE];
+               break;
+       case AF_INET6:
+               tbl = neigh_tables[NEIGH_ND_TABLE];
+               break;
+       case AF_DECnet:
+               tbl = neigh_tables[NEIGH_DN_TABLE];
+               break;
+       }
+
+       return tbl;
+}
+
 static int neigh_delete(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
        struct net *net = sock_net(skb->sk);
        struct ndmsg *ndm;
        struct nlattr *dst_attr;
        struct neigh_table *tbl;
+       struct neighbour *neigh;
        struct net_device *dev = NULL;
        int err = -EINVAL;
 
@@ -1652,39 +1640,31 @@ static int neigh_delete(struct sk_buff *skb, struct nlmsghdr *nlh)
                }
        }
 
-       read_lock(&neigh_tbl_lock);
-       for (tbl = neigh_tables; tbl; tbl = tbl->next) {
-               struct neighbour *neigh;
-
-               if (tbl->family != ndm->ndm_family)
-                       continue;
-               read_unlock(&neigh_tbl_lock);
-
-               if (nla_len(dst_attr) < tbl->key_len)
-                       goto out;
+       tbl = neigh_find_table(ndm->ndm_family);
+       if (tbl == NULL)
+               return -EAFNOSUPPORT;
 
-               if (ndm->ndm_flags & NTF_PROXY) {
-                       err = pneigh_delete(tbl, net, nla_data(dst_attr), dev);
-                       goto out;
-               }
+       if (nla_len(dst_attr) < tbl->key_len)
+               goto out;
 
-               if (dev == NULL)
-                       goto out;
+       if (ndm->ndm_flags & NTF_PROXY) {
+               err = pneigh_delete(tbl, net, nla_data(dst_attr), dev);
+               goto out;
+       }
 
-               neigh = neigh_lookup(tbl, nla_data(dst_attr), dev);
-               if (neigh == NULL) {
-                       err = -ENOENT;
-                       goto out;
-               }
+       if (dev == NULL)
+               goto out;
 
-               err = neigh_update(neigh, NULL, NUD_FAILED,
-                                  NEIGH_UPDATE_F_OVERRIDE |
-                                  NEIGH_UPDATE_F_ADMIN);
-               neigh_release(neigh);
+       neigh = neigh_lookup(tbl, nla_data(dst_attr), dev);
+       if (neigh == NULL) {
+               err = -ENOENT;
                goto out;
        }
-       read_unlock(&neigh_tbl_lock);
-       err = -EAFNOSUPPORT;
+
+       err = neigh_update(neigh, NULL, NUD_FAILED,
+                          NEIGH_UPDATE_F_OVERRIDE |
+                          NEIGH_UPDATE_F_ADMIN);
+       neigh_release(neigh);
 
 out:
        return err;
@@ -1692,11 +1672,14 @@ out:
 
 static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
+       int flags = NEIGH_UPDATE_F_ADMIN | NEIGH_UPDATE_F_OVERRIDE;
        struct net *net = sock_net(skb->sk);
        struct ndmsg *ndm;
        struct nlattr *tb[NDA_MAX+1];
        struct neigh_table *tbl;
        struct net_device *dev = NULL;
+       struct neighbour *neigh;
+       void *dst, *lladdr;
        int err;
 
        ASSERT_RTNL();
@@ -1720,70 +1703,60 @@ static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh)
                        goto out;
        }
 
-       read_lock(&neigh_tbl_lock);
-       for (tbl = neigh_tables; tbl; tbl = tbl->next) {
-               int flags = NEIGH_UPDATE_F_ADMIN | NEIGH_UPDATE_F_OVERRIDE;
-               struct neighbour *neigh;
-               void *dst, *lladdr;
+       tbl = neigh_find_table(ndm->ndm_family);
+       if (tbl == NULL)
+               return -EAFNOSUPPORT;
 
-               if (tbl->family != ndm->ndm_family)
-                       continue;
-               read_unlock(&neigh_tbl_lock);
+       if (nla_len(tb[NDA_DST]) < tbl->key_len)
+               goto out;
+       dst = nla_data(tb[NDA_DST]);
+       lladdr = tb[NDA_LLADDR] ? nla_data(tb[NDA_LLADDR]) : NULL;
 
-               if (nla_len(tb[NDA_DST]) < tbl->key_len)
-                       goto out;
-               dst = nla_data(tb[NDA_DST]);
-               lladdr = tb[NDA_LLADDR] ? nla_data(tb[NDA_LLADDR]) : NULL;
+       if (ndm->ndm_flags & NTF_PROXY) {
+               struct pneigh_entry *pn;
+
+               err = -ENOBUFS;
+               pn = pneigh_lookup(tbl, net, dst, dev, 1);
+               if (pn) {
+                       pn->flags = ndm->ndm_flags;
+                       err = 0;
+               }
+               goto out;
+       }
 
-               if (ndm->ndm_flags & NTF_PROXY) {
-                       struct pneigh_entry *pn;
+       if (dev == NULL)
+               goto out;
 
-                       err = -ENOBUFS;
-                       pn = pneigh_lookup(tbl, net, dst, dev, 1);
-                       if (pn) {
-                               pn->flags = ndm->ndm_flags;
-                               err = 0;
-                       }
+       neigh = neigh_lookup(tbl, dst, dev);
+       if (neigh == NULL) {
+               if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
+                       err = -ENOENT;
                        goto out;
                }
 
-               if (dev == NULL)
+               neigh = __neigh_lookup_errno(tbl, dst, dev);
+               if (IS_ERR(neigh)) {
+                       err = PTR_ERR(neigh);
+                       goto out;
+               }
+       } else {
+               if (nlh->nlmsg_flags & NLM_F_EXCL) {
+                       err = -EEXIST;
+                       neigh_release(neigh);
                        goto out;
-
-               neigh = neigh_lookup(tbl, dst, dev);
-               if (neigh == NULL) {
-                       if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
-                               err = -ENOENT;
-                               goto out;
-                       }
-
-                       neigh = __neigh_lookup_errno(tbl, dst, dev);
-                       if (IS_ERR(neigh)) {
-                               err = PTR_ERR(neigh);
-                               goto out;
-                       }
-               } else {
-                       if (nlh->nlmsg_flags & NLM_F_EXCL) {
-                               err = -EEXIST;
-                               neigh_release(neigh);
-                               goto out;
-                       }
-
-                       if (!(nlh->nlmsg_flags & NLM_F_REPLACE))
-                               flags &= ~NEIGH_UPDATE_F_OVERRIDE;
                }
 
-               if (ndm->ndm_flags & NTF_USE) {
-                       neigh_event_send(neigh, NULL);
-                       err = 0;
-               } else
-                       err = neigh_update(neigh, lladdr, ndm->ndm_state, flags);
-               neigh_release(neigh);
-               goto out;
+               if (!(nlh->nlmsg_flags & NLM_F_REPLACE))
+                       flags &= ~NEIGH_UPDATE_F_OVERRIDE;
        }
 
-       read_unlock(&neigh_tbl_lock);
-       err = -EAFNOSUPPORT;
+       if (ndm->ndm_flags & NTF_USE) {
+               neigh_event_send(neigh, NULL);
+               err = 0;
+       } else
+               err = neigh_update(neigh, lladdr, ndm->ndm_state, flags);
+       neigh_release(neigh);
+
 out:
        return err;
 }
@@ -1982,7 +1955,8 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh)
        struct neigh_table *tbl;
        struct ndtmsg *ndtmsg;
        struct nlattr *tb[NDTA_MAX+1];
-       int err;
+       bool found = false;
+       int err, tidx;
 
        err = nlmsg_parse(nlh, sizeof(*ndtmsg), tb, NDTA_MAX,
                          nl_neightbl_policy);
@@ -1995,19 +1969,21 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh)
        }
 
        ndtmsg = nlmsg_data(nlh);
-       read_lock(&neigh_tbl_lock);
-       for (tbl = neigh_tables; tbl; tbl = tbl->next) {
+
+       for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) {
+               tbl = neigh_tables[tidx];
+               if (!tbl)
+                       continue;
                if (ndtmsg->ndtm_family && tbl->family != ndtmsg->ndtm_family)
                        continue;
-
-               if (nla_strcmp(tb[NDTA_NAME], tbl->id) == 0)
+               if (nla_strcmp(tb[NDTA_NAME], tbl->id) == 0) {
+                       found = true;
                        break;
+               }
        }
 
-       if (tbl == NULL) {
-               err = -ENOENT;
-               goto errout_locked;
-       }
+       if (!found)
+               return -ENOENT;
 
        /*
         * We acquire tbl->lock to be nice to the periodic timers and
@@ -2118,8 +2094,6 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh)
 
 errout_tbl_lock:
        write_unlock_bh(&tbl->lock);
-errout_locked:
-       read_unlock(&neigh_tbl_lock);
 errout:
        return err;
 }
@@ -2134,10 +2108,13 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
 
        family = ((struct rtgenmsg *) nlmsg_data(cb->nlh))->rtgen_family;
 
-       read_lock(&neigh_tbl_lock);
-       for (tbl = neigh_tables, tidx = 0; tbl; tbl = tbl->next, tidx++) {
+       for (tidx = 0; tidx < NEIGH_NR_TABLES; tidx++) {
                struct neigh_parms *p;
 
+               tbl = neigh_tables[tidx];
+               if (!tbl)
+                       continue;
+
                if (tidx < tbl_skip || (family && tbl->family != family))
                        continue;
 
@@ -2168,7 +2145,6 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
                neigh_skip = 0;
        }
 out:
-       read_unlock(&neigh_tbl_lock);
        cb->args[0] = tidx;
        cb->args[1] = nidx;
 
@@ -2351,7 +2327,6 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
        int proxy = 0;
        int err;
 
-       read_lock(&neigh_tbl_lock);
        family = ((struct rtgenmsg *) nlmsg_data(cb->nlh))->rtgen_family;
 
        /* check for full ndmsg structure presence, family member is
@@ -2363,8 +2338,11 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
 
        s_t = cb->args[0];
 
-       for (tbl = neigh_tables, t = 0; tbl;
-            tbl = tbl->next, t++) {
+       for (t = 0; t < NEIGH_NR_TABLES; t++) {
+               tbl = neigh_tables[t];
+
+               if (!tbl)
+                       continue;
                if (t < s_t || (family && tbl->family != family))
                        continue;
                if (t > s_t)
@@ -2377,7 +2355,6 @@ static int neigh_dump_info(struct sk_buff *skb, struct netlink_callback *cb)
                if (err < 0)
                        break;
        }
-       read_unlock(&neigh_tbl_lock);
 
        cb->args[0] = t;
        return skb->len;

diff --git a/net/decnet/dn_neigh.c b/net/decnet/dn_neigh.c
index c8121ce..7ca7c31 100644 (file)
--- a/net/decnet/dn_neigh.c
+++ b/net/decnet/dn_neigh.c
@@ -591,7 +591,7 @@ static const struct file_operations dn_neigh_seq_fops = {
 
 void __init dn_neigh_init(void)
 {
-       neigh_table_init(&dn_neigh_table);
+       neigh_table_init(NEIGH_DN_TABLE, &dn_neigh_table);
        proc_create("decnet_neigh", S_IRUGO, init_net.proc_net,
                    &dn_neigh_seq_fops);
 }
@@ -599,5 +599,5 @@ void __init dn_neigh_init(void)
 void __exit dn_neigh_cleanup(void)
 {
        remove_proc_entry("decnet_neigh", init_net.proc_net);
-       neigh_table_clear(&dn_neigh_table);
+       neigh_table_clear(NEIGH_DN_TABLE, &dn_neigh_table);
 }

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 16acb59..205e147 100644 (file)
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1292,7 +1292,7 @@ static int arp_proc_init(void);
 
 void __init arp_init(void)
 {
-       neigh_table_init(&arp_tbl);
+       neigh_table_init(NEIGH_ARP_TABLE, &arp_tbl);
 
        dev_add_pack(&arp_packet_type);
        arp_proc_init();

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 4cb45c1..2c9f6bf 100644 (file)
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1763,7 +1763,7 @@ int __init ndisc_init(void)
        /*
         * Initialize the neighbour table
         */
-       neigh_table_init(&nd_tbl);
+       neigh_table_init(NEIGH_ND_TABLE, &nd_tbl);
 
 #ifdef CONFIG_SYSCTL
        err = neigh_sysctl_register(NULL, &nd_tbl.parms,
@@ -1796,6 +1796,6 @@ void ndisc_cleanup(void)
 #ifdef CONFIG_SYSCTL
        neigh_sysctl_unregister(&nd_tbl.parms);
 #endif
-       neigh_table_clear(&nd_tbl);
+       neigh_table_clear(NEIGH_ND_TABLE, &nd_tbl);
        unregister_pernet_subsys(&ndisc_net_ops);
 }