Merge branch 'fib_trie_table_merge_fixes'

Alexander Duyck says:

====================
fib_trie: Minor fixes for table merge

This patch set addresses two issues reported with the tables merged, the
first is a NULL pointer dereference, and the other is to remove a WARN_ON
and set the ordering for aliases from different tables with the same slen
values.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/fib_frontend.c

@@ -156,9 +156,12 @@ int fib_unmerge(struct net *net)
 {
 	struct fib_table *old, *new;
 
+	/* attempt to fetch local table if it has been allocated */
 	old = fib_get_table(net, RT_TABLE_LOCAL);
-	new = fib_trie_unmerge(old);
+	if (!old)
+		return 0;
 
+	new = fib_trie_unmerge(old);
 	if (!new)
 		return -ENOMEM;
 

net/ipv4/fib_trie.c

@@ -950,7 +950,7 @@ static struct key_vector *fib_find_node(struct trie *t,
  * priority less than or equal to PRIO.
  */
 static struct fib_alias *fib_find_alias(struct hlist_head *fah, u8 slen,
-					u8 tos, u32 prio)
+					u8 tos, u32 prio, u32 tb_id)
 {
 	struct fib_alias *fa;
 
@@ -962,6 +962,10 @@ static struct fib_alias *fib_find_alias(struct hlist_head *fah, u8 slen,
 			continue;
 		if (fa->fa_slen != slen)
 			break;
+		if (fa->tb_id > tb_id)
+			continue;
+		if (fa->tb_id != tb_id)
+			break;
 		if (fa->fa_tos > tos)
 			continue;
 		if (fa->fa_info->fib_priority >= prio || fa->fa_tos < tos)
@@ -1041,6 +1045,9 @@ static int fib_insert_alias(struct trie *t, struct key_vector *tp,
 		hlist_for_each_entry(last, &l->leaf, fa_list) {
 			if (new->fa_slen < last->fa_slen)
 				break;
+			if ((new->fa_slen == last->fa_slen) &&
+			    (new->tb_id > last->tb_id))
+				break;
 			fa = last;
 		}
 
@@ -1089,7 +1096,8 @@ int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
 	}
 
 	l = fib_find_node(t, &tp, key);
-	fa = l ? fib_find_alias(&l->leaf, slen, tos, fi->fib_priority) : NULL;
+	fa = l ? fib_find_alias(&l->leaf, slen, tos, fi->fib_priority,
+				tb->tb_id) : NULL;
 
 	/* Now fa, if non-NULL, points to the first fib alias
 	 * with the same keys [prefix,tos,priority], if such key already
@@ -1116,13 +1124,12 @@ int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
 		fa_match = NULL;
 		fa_first = fa;
 		hlist_for_each_entry_from(fa, fa_list) {
-			if ((fa->fa_slen != slen) || (fa->fa_tos != tos))
+			if ((fa->fa_slen != slen) ||
+			    (fa->tb_id != tb->tb_id) ||
+			    (fa->fa_tos != tos))
 				break;
 			if (fa->fa_info->fib_priority != fi->fib_priority)
 				break;
-			/* duplicate entry from another table */
-			if (WARN_ON(fa->tb_id != tb->tb_id))
-				continue;
 			if (fa->fa_type == cfg->fc_type &&
 			    fa->fa_info == fi) {
 				fa_match = fa;
@@ -1474,7 +1481,7 @@ int fib_table_delete(struct fib_table *tb, struct fib_config *cfg)
 	if (!l)
 		return -ESRCH;
 
-	fa = fib_find_alias(&l->leaf, slen, tos, 0);
+	fa = fib_find_alias(&l->leaf, slen, tos, 0, tb->tb_id);
 	if (!fa)
 		return -ESRCH;
 
@@ -1484,12 +1491,11 @@ int fib_table_delete(struct fib_table *tb, struct fib_config *cfg)
 	hlist_for_each_entry_from(fa, fa_list) {
 		struct fib_info *fi = fa->fa_info;
 
-		if ((fa->fa_slen != slen) || (fa->fa_tos != tos))
+		if ((fa->fa_slen != slen) ||
+		    (fa->tb_id != tb->tb_id) ||
+		    (fa->fa_tos != tos))
 			break;
 
-		if (fa->tb_id != tb->tb_id)
-			continue;
-
 		if ((!cfg->fc_type || fa->fa_type == cfg->fc_type) &&
 		    (cfg->fc_scope == RT_SCOPE_NOWHERE ||
 		     fa->fa_info->fib_scope == cfg->fc_scope) &&