[IPV4]: Increase number of possible routing tables to 2^32

Increase the number of possible routing tables to 2^32 by replacing the
fixed sized array of pointers by a hash table and replacing iterations
over all possible table IDs by hash table walking.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_fib.h

@@ -150,6 +150,7 @@ struct fib_result_nl {
 #endif /* CONFIG_IP_ROUTE_MULTIPATH_WRANDOM */
 
 struct fib_table {
+	struct hlist_node tb_hlist;
 	u32		tb_id;
 	unsigned	tb_stamp;
 	int		(*tb_lookup)(struct fib_table *tb, const struct flowi *flp, struct fib_result *res);
@@ -200,29 +201,13 @@ static inline void fib_select_default(const struct flowi *flp, struct fib_result
 }
 
 #else /* CONFIG_IP_MULTIPLE_TABLES */
-#define ip_fib_local_table (fib_tables[RT_TABLE_LOCAL])
-#define ip_fib_main_table (fib_tables[RT_TABLE_MAIN])
+#define ip_fib_local_table fib_get_table(RT_TABLE_LOCAL)
+#define ip_fib_main_table fib_get_table(RT_TABLE_MAIN)
 
-extern struct fib_table * fib_tables[RT_TABLE_MAX+1];
 extern int fib_lookup(struct flowi *flp, struct fib_result *res);
-extern struct fib_table *__fib_new_table(u32 id);
-
-static inline struct fib_table *fib_get_table(u32 id)
-{
-	if (id == 0)
-		id = RT_TABLE_MAIN;
-
-	return fib_tables[id];
-}
-
-static inline struct fib_table *fib_new_table(u32 id)
-{
-	if (id == 0)
-		id = RT_TABLE_MAIN;
-
-	return fib_tables[id] ? : __fib_new_table(id);
-}
 
+extern struct fib_table *fib_new_table(u32 id);
+extern struct fib_table *fib_get_table(u32 id);
 extern void fib_select_default(const struct flowi *flp, struct fib_result *res);
 
 #endif /* CONFIG_IP_MULTIPLE_TABLES */

net/ipv4/fib_frontend.c

@@ -37,6 +37,7 @@
 #include <linux/skbuff.h>
 #include <linux/netlink.h>
 #include <linux/init.h>
+#include <linux/list.h>
 
 #include <net/ip.h>
 #include <net/protocol.h>
@@ -51,48 +52,67 @@
 
 #ifndef CONFIG_IP_MULTIPLE_TABLES
 
-#define RT_TABLE_MIN RT_TABLE_MAIN
-
 struct fib_table *ip_fib_local_table;
 struct fib_table *ip_fib_main_table;
 
-#else
+#define FIB_TABLE_HASHSZ 1
+static struct hlist_head fib_table_hash[FIB_TABLE_HASHSZ];
 
-#define RT_TABLE_MIN 1
+#else
 
-struct fib_table *fib_tables[RT_TABLE_MAX+1];
+#define FIB_TABLE_HASHSZ 256
+static struct hlist_head fib_table_hash[FIB_TABLE_HASHSZ];
 
-struct fib_table *__fib_new_table(u32 id)
+struct fib_table *fib_new_table(u32 id)
 {
 	struct fib_table *tb;
+	unsigned int h;
 
+	if (id == 0)
+		id = RT_TABLE_MAIN;
+	tb = fib_get_table(id);
+	if (tb)
+		return tb;
 	tb = fib_hash_init(id);
 	if (!tb)
 		return NULL;
-	fib_tables[id] = tb;
+	h = id & (FIB_TABLE_HASHSZ - 1);
+	hlist_add_head_rcu(&tb->tb_hlist, &fib_table_hash[h]);
 	return tb;
 }
 
+struct fib_table *fib_get_table(u32 id)
+{
+	struct fib_table *tb;
+	struct hlist_node *node;
+	unsigned int h;
 
+	if (id == 0)
+		id = RT_TABLE_MAIN;
+	h = id & (FIB_TABLE_HASHSZ - 1);
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(tb, node, &fib_table_hash[h], tb_hlist) {
+		if (tb->tb_id == id) {
+			rcu_read_unlock();
+			return tb;
+		}
+	}
+	rcu_read_unlock();
+	return NULL;
+}
 #endif /* CONFIG_IP_MULTIPLE_TABLES */
 
-
 static void fib_flush(void)
 {
 	int flushed = 0;
-#ifdef CONFIG_IP_MULTIPLE_TABLES
 	struct fib_table *tb;
-	u32 id;
+	struct hlist_node *node;
+	unsigned int h;
 
-	for (id = RT_TABLE_MAX; id>0; id--) {
-		if ((tb = fib_get_table(id))==NULL)
-			continue;
+	for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
+		hlist_for_each_entry(tb, node, &fib_table_hash[h], tb_hlist)
 			flushed += tb->tb_flush(tb);
 	}
-#else /* CONFIG_IP_MULTIPLE_TABLES */
-	flushed += ip_fib_main_table->tb_flush(ip_fib_main_table);
-	flushed += ip_fib_local_table->tb_flush(ip_fib_local_table);
-#endif /* CONFIG_IP_MULTIPLE_TABLES */
 
 	if (flushed)
 		rt_cache_flush(-1);
@@ -334,29 +354,37 @@ int inet_rtm_newroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 
 int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	u32 t;
-	u32 s_t;
+	unsigned int h, s_h;
+	unsigned int e = 0, s_e;
 	struct fib_table *tb;
+	struct hlist_node *node;
+	int dumped = 0;
 
 	if (NLMSG_PAYLOAD(cb->nlh, 0) >= sizeof(struct rtmsg) &&
 	    ((struct rtmsg*)NLMSG_DATA(cb->nlh))->rtm_flags&RTM_F_CLONED)
 		return ip_rt_dump(skb, cb);
 
-	s_t = cb->args[0];
-	if (s_t == 0)
-		s_t = cb->args[0] = RT_TABLE_MIN;
-
-	for (t=s_t; t<=RT_TABLE_MAX; t++) {
-		if (t < s_t) continue;
-		if (t > s_t)
-			memset(&cb->args[1], 0, sizeof(cb->args)-sizeof(cb->args[0]));
-		if ((tb = fib_get_table(t))==NULL)
-			continue;
+	s_h = cb->args[0];
+	s_e = cb->args[1];
+
+	for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
+		e = 0;
+		hlist_for_each_entry(tb, node, &fib_table_hash[h], tb_hlist) {
+			if (e < s_e)
+				goto next;
+			if (dumped)
+				memset(&cb->args[2], 0, sizeof(cb->args) -
+				                 2 * sizeof(cb->args[0]));
 			if (tb->tb_dump(tb, skb, cb) < 0)
-			break;
+				goto out;
+			dumped = 1;
+next:
+			e++;
 		}
-
-	cb->args[0] = t;
+	}
+out:
+	cb->args[1] = e;
+	cb->args[0] = h;
 
 	return skb->len;
 }
@@ -654,9 +682,15 @@ static struct notifier_block fib_netdev_notifier = {
 
 void __init ip_fib_init(void)
 {
+	unsigned int i;
+
+	for (i = 0; i < FIB_TABLE_HASHSZ; i++)
+		INIT_HLIST_HEAD(&fib_table_hash[i]);
 #ifndef CONFIG_IP_MULTIPLE_TABLES
 	ip_fib_local_table = fib_hash_init(RT_TABLE_LOCAL);
+	hlist_add_head_rcu(&ip_fib_local_table->tb_hlist, &fib_table_hash[0]);
 	ip_fib_main_table  = fib_hash_init(RT_TABLE_MAIN);
+	hlist_add_head_rcu(&ip_fib_main_table->tb_hlist, &fib_table_hash[0]);
 #else
 	fib4_rules_init();
 #endif

net/ipv4/fib_hash.c

@@ -684,7 +684,7 @@ fn_hash_dump_bucket(struct sk_buff *skb, struct netlink_callback *cb,
 	struct fib_node *f;
 	int i, s_i;
 
-	s_i = cb->args[3];
+	s_i = cb->args[4];
 	i = 0;
 	hlist_for_each_entry(f, node, head, fn_hash) {
 		struct fib_alias *fa;
@@ -704,14 +704,14 @@ fn_hash_dump_bucket(struct sk_buff *skb, struct netlink_callback *cb,
 					  fa->fa_tos,
 					  fa->fa_info,
 					  NLM_F_MULTI) < 0) {
-				cb->args[3] = i;
+				cb->args[4] = i;
 				return -1;
 			}
 		next:
 			i++;
 		}
 	}
-	cb->args[3] = i;
+	cb->args[4] = i;
 	return skb->len;
 }
 
@@ -722,21 +722,21 @@ fn_hash_dump_zone(struct sk_buff *skb, struct netlink_callback *cb,
 {
 	int h, s_h;
 
-	s_h = cb->args[2];
+	s_h = cb->args[3];
 	for (h=0; h < fz->fz_divisor; h++) {
 		if (h < s_h) continue;
 		if (h > s_h)
-			memset(&cb->args[3], 0,
-			       sizeof(cb->args) - 3*sizeof(cb->args[0]));
+			memset(&cb->args[4], 0,
+			       sizeof(cb->args) - 4*sizeof(cb->args[0]));
 		if (fz->fz_hash == NULL ||
 		    hlist_empty(&fz->fz_hash[h]))
 			continue;
 		if (fn_hash_dump_bucket(skb, cb, tb, fz, &fz->fz_hash[h])<0) {
-			cb->args[2] = h;
+			cb->args[3] = h;
 			return -1;
 		}
 	}
-	cb->args[2] = h;
+	cb->args[3] = h;
 	return skb->len;
 }
 
@@ -746,21 +746,21 @@ static int fn_hash_dump(struct fib_table *tb, struct sk_buff *skb, struct netlin
 	struct fn_zone *fz;
 	struct fn_hash *table = (struct fn_hash*)tb->tb_data;
 
-	s_m = cb->args[1];
+	s_m = cb->args[2];
 	read_lock(&fib_hash_lock);
 	for (fz = table->fn_zone_list, m=0; fz; fz = fz->fz_next, m++) {
 		if (m < s_m) continue;
 		if (m > s_m)
-			memset(&cb->args[2], 0,
-			       sizeof(cb->args) - 2*sizeof(cb->args[0]));
+			memset(&cb->args[3], 0,
+			       sizeof(cb->args) - 3*sizeof(cb->args[0]));
 		if (fn_hash_dump_zone(skb, cb, tb, fz) < 0) {
-			cb->args[1] = m;
+			cb->args[2] = m;
 			read_unlock(&fib_hash_lock);
 			return -1;
 		}
 	}
 	read_unlock(&fib_hash_lock);
-	cb->args[1] = m;
+	cb->args[2] = m;
 	return skb->len;
 }
 

net/ipv4/fib_rules.c

@@ -172,8 +172,8 @@ static struct fib_table *fib_empty_table(void)
 	u32 id;
 
 	for (id = 1; id <= RT_TABLE_MAX; id++)
-		if (fib_tables[id] == NULL)
-			return __fib_new_table(id);
+		if (fib_get_table(id) == NULL)
+			return fib_new_table(id);
 	return NULL;
 }
 

net/ipv4/fib_trie.c

@@ -1848,7 +1848,7 @@ static int fn_trie_dump_fa(t_key key, int plen, struct list_head *fah, struct fi
 
 	u32 xkey = htonl(key);
 
-	s_i = cb->args[3];
+	s_i = cb->args[4];
 	i = 0;
 
 	/* rcu_read_lock is hold by caller */
@@ -1870,12 +1870,12 @@ static int fn_trie_dump_fa(t_key key, int plen, struct list_head *fah, struct fi
 				  plen,
 				  fa->fa_tos,
 				  fa->fa_info, 0) < 0) {
-			cb->args[3] = i;
+			cb->args[4] = i;
 			return -1;
 		}
 		i++;
 	}
-	cb->args[3] = i;
+	cb->args[4] = i;
 	return skb->len;
 }
 
@@ -1886,14 +1886,14 @@ static int fn_trie_dump_plen(struct trie *t, int plen, struct fib_table *tb, str
 	struct list_head *fa_head;
 	struct leaf *l = NULL;
 
-	s_h = cb->args[2];
+	s_h = cb->args[3];
 
 	for (h = 0; (l = nextleaf(t, l)) != NULL; h++) {
 		if (h < s_h)
 			continue;
 		if (h > s_h)
-			memset(&cb->args[3], 0,
-			       sizeof(cb->args) - 3*sizeof(cb->args[0]));
+			memset(&cb->args[4], 0,
+			       sizeof(cb->args) - 4*sizeof(cb->args[0]));
 
 		fa_head = get_fa_head(l, plen);
 
@@ -1904,11 +1904,11 @@ static int fn_trie_dump_plen(struct trie *t, int plen, struct fib_table *tb, str
 			continue;
 
 		if (fn_trie_dump_fa(l->key, plen, fa_head, tb, skb, cb)<0) {
-			cb->args[2] = h;
+			cb->args[3] = h;
 			return -1;
 		}
 	}
-	cb->args[2] = h;
+	cb->args[3] = h;
 	return skb->len;
 }
 
@@ -1917,23 +1917,23 @@ static int fn_trie_dump(struct fib_table *tb, struct sk_buff *skb, struct netlin
 	int m, s_m;
 	struct trie *t = (struct trie *) tb->tb_data;
 
-	s_m = cb->args[1];
+	s_m = cb->args[2];
 
 	rcu_read_lock();
 	for (m = 0; m <= 32; m++) {
 		if (m < s_m)
 			continue;
 		if (m > s_m)
-			memset(&cb->args[2], 0,
-				sizeof(cb->args) - 2*sizeof(cb->args[0]));
+			memset(&cb->args[3], 0,
+				sizeof(cb->args) - 3*sizeof(cb->args[0]));
 
 		if (fn_trie_dump_plen(t, 32-m, tb, skb, cb)<0) {
-			cb->args[1] = m;
+			cb->args[2] = m;
 			goto out;
 		}
 	}
 	rcu_read_unlock();
-	cb->args[1] = m;
+	cb->args[2] = m;
 	return skb->len;
 out:
 	rcu_read_unlock();