fib_trie: Fib find node should return parent

This change makes it so that the parent pointer is returned by reference in
fib_find_node.  By doing this I can use it to find the parent node when I
am performing an insertion and I don't have to look for it again in
fib_insert_node.

Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index bf488ce..5d0f145 100644 (file)
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -912,9 +912,9 @@ static void fib_insert_alias(struct tnode *l, struct fib_alias *fa,
 }
 
 /* rcu_read_lock needs to be hold by caller from readside */
-static struct tnode *fib_find_node(struct trie *t, u32 key)
+static struct tnode *fib_find_node(struct trie *t, struct tnode **tn, u32 key)
 {
-       struct tnode *n = rcu_dereference_rtnl(t->trie);
+       struct tnode *pn = NULL, *n = rcu_dereference_rtnl(t->trie);
 
        while (n) {
                unsigned long index = get_index(key, n);
@@ -924,21 +924,30 @@ static struct tnode *fib_find_node(struct trie *t, u32 key)
                 * prefix plus zeros for the bits in the cindex. The index
                 * is the difference between the key and this value.  From
                 * this we can actually derive several pieces of data.
-                *   if (index & (~0ul << bits))
+                *   if (index >= (1ul << bits))
                 *     we have a mismatch in skip bits and failed
                 *   else
                 *     we know the value is cindex
+                *
+                * This check is safe even if bits == KEYLENGTH due to the
+                * fact that we can only allocate a node with 32 bits if a
+                * long is greater than 32 bits.
                 */
-               if (index & (~0ul << n->bits))
-                       return NULL;
+               if (index >= (1ul << n->bits)) {
+                       n = NULL;
+                       break;
+               }
 
                /* we have found a leaf. Prefixes have already been compared */
                if (IS_LEAF(n))
                        break;
 
+               pn = n;
                n = tnode_get_child_rcu(n, index);
        }
 
+       *tn = pn;
+
        return n;
 }
 
@@ -1071,15 +1080,15 @@ static struct tnode *fib_insert_node(struct trie *t, u32 key, int plen)
  */
 int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
 {
-       struct trie *t = (struct trie *) tb->tb_data;
+       struct trie *t = (struct trie *)tb->tb_data;
        struct fib_alias *fa, *new_fa;
+       struct tnode *l, *tp;
        struct fib_info *fi;
        u8 plen = cfg->fc_dst_len;
        u8 slen = KEYLENGTH - plen;
        u8 tos = cfg->fc_tos;
-       u32 key, mask;
+       u32 key;
        int err;
-       struct tnode *l;
 
        if (plen > KEYLENGTH)
                return -EINVAL;
@@ -1088,9 +1097,7 @@ int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
 
        pr_debug("Insert table=%u %08x/%d\n", tb->tb_id, key, plen);
 
-       mask = ntohl(inet_make_mask(plen));
-
-       if (key & ~mask)
+       if ((plen < KEYLENGTH) && (key << plen))
                return -EINVAL;
 
        fi = fib_create_info(cfg);
@@ -1099,7 +1106,7 @@ int fib_table_insert(struct fib_table *tb, struct fib_config *cfg)
                goto err;
        }
 
-       l = fib_find_node(t, key);
+       l = fib_find_node(t, &tp, key);
        fa = l ? fib_find_alias(&l->leaf, slen, tos, fi->fib_priority) : NULL;
 
        /* Now fa, if non-NULL, points to the first fib alias
@@ -1406,22 +1413,21 @@ int fib_table_delete(struct fib_table *tb, struct fib_config *cfg)
 {
        struct trie *t = (struct trie *) tb->tb_data;
        struct fib_alias *fa, *fa_to_delete;
+       struct tnode *l, *tp;
        u8 plen = cfg->fc_dst_len;
-       u8 tos = cfg->fc_tos;
        u8 slen = KEYLENGTH - plen;
-       struct tnode *l;
-       u32 key, mask;
+       u8 tos = cfg->fc_tos;
+       u32 key;
 
        if (plen > KEYLENGTH)
                return -EINVAL;
 
        key = ntohl(cfg->fc_dst);
-       mask = ntohl(inet_make_mask(plen));
 
-       if (key & ~mask)
+       if ((plen < KEYLENGTH) && (key << plen))
                return -EINVAL;
 
-       l = fib_find_node(t, key);
+       l = fib_find_node(t, &tp, key);
        if (!l)
                return -ESRCH;