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fib_trie: Fib walk rcu should take a tnode and key instead of a trie and a leaf
This change makes it so that leaf_walk_rcu takes a tnode and a key instead of the trie and a leaf. The main idea behind this is to avoid using the leaf parent pointer as that can have additional overhead in the future as I am trying to reduce the size of a leaf down to 16 bytes on 64b systems and 12b on 32b systems. Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck
David S. Miller
parent
7289e6ddb6
commit
8be33e955c
@ -1485,71 +1485,71 @@ int fib_table_delete(struct fib_table *tb, struct fib_config *cfg)
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return 0;
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}
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/* Scan for the next right leaf starting at node p->child[idx]
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* Since we have back pointer, no recursion necessary.
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*/
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static struct tnode *leaf_walk_rcu(struct tnode *p, struct tnode *c)
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/* Scan for the next leaf starting at the provided key value */
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static struct tnode *leaf_walk_rcu(struct tnode **tn, t_key key)
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{
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do {
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unsigned long idx = c ? idx = get_index(c->key, p) + 1 : 0;
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struct tnode *pn, *n = *tn;
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unsigned long cindex;
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while (idx < tnode_child_length(p)) {
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c = tnode_get_child_rcu(p, idx++);
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if (!c)
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continue;
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/* record parent node for backtracing */
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pn = n;
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cindex = n ? get_index(key, n) : 0;
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if (IS_LEAF(c))
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return c;
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/* this loop is meant to try and find the key in the trie */
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while (n) {
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unsigned long idx = get_index(key, n);
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/* Rescan start scanning in new node */
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p = c;
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idx = 0;
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/* guarantee forward progress on the keys */
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if (IS_LEAF(n) && (n->key >= key))
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goto found;
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if (idx >= (1ul << n->bits))
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break;
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/* record parent and next child index */
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pn = n;
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cindex = idx;
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/* descend into the next child */
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n = tnode_get_child_rcu(pn, cindex++);
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}
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/* this loop will search for the next leaf with a greater key */
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while (pn) {
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/* if we exhausted the parent node we will need to climb */
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if (cindex >= (1ul << pn->bits)) {
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t_key pkey = pn->key;
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pn = node_parent_rcu(pn);
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if (!pn)
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break;
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cindex = get_index(pkey, pn) + 1;
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continue;
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}
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/* Node empty, walk back up to parent */
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c = p;
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} while ((p = node_parent_rcu(c)) != NULL);
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/* grab the next available node */
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n = tnode_get_child_rcu(pn, cindex++);
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if (!n)
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continue;
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/* no need to compare keys since we bumped the index */
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if (IS_LEAF(n))
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goto found;
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/* Rescan start scanning in new node */
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pn = n;
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cindex = 0;
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}
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*tn = pn;
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return NULL; /* Root of trie */
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found:
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/* if we are at the limit for keys just return NULL for the tnode */
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*tn = (n->key == KEY_MAX) ? NULL : pn;
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return n;
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}
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static struct tnode *trie_firstleaf(struct trie *t)
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{
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struct tnode *n = rcu_dereference_rtnl(t->trie);
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if (!n)
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return NULL;
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if (IS_LEAF(n)) /* trie is just a leaf */
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return n;
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return leaf_walk_rcu(n, NULL);
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}
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static struct tnode *trie_nextleaf(struct tnode *l)
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{
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struct tnode *p = node_parent_rcu(l);
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if (!p)
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return NULL; /* trie with just one leaf */
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return leaf_walk_rcu(p, l);
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}
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static struct tnode *trie_leafindex(struct trie *t, int index)
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{
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struct tnode *l = trie_firstleaf(t);
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while (l && index-- > 0)
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l = trie_nextleaf(l);
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return l;
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}
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/*
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* Caller must hold RTNL.
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*/
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/* Caller must hold RTNL. */
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int fib_table_flush(struct fib_table *tb)
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{
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struct trie *t = (struct trie *)tb->tb_data;
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@ -1680,42 +1680,42 @@ static int fn_trie_dump_leaf(struct tnode *l, struct fib_table *tb,
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int fib_table_dump(struct fib_table *tb, struct sk_buff *skb,
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struct netlink_callback *cb)
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{
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struct tnode *l;
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struct trie *t = (struct trie *) tb->tb_data;
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t_key key = cb->args[2];
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int count = cb->args[3];
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rcu_read_lock();
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struct trie *t = (struct trie *)tb->tb_data;
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struct tnode *l, *tp;
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/* Dump starting at last key.
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* Note: 0.0.0.0/0 (ie default) is first key.
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*/
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if (count == 0)
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l = trie_firstleaf(t);
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else {
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/* Normally, continue from last key, but if that is missing
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* fallback to using slow rescan
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*/
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l = fib_find_node(t, key);
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if (!l)
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l = trie_leafindex(t, count);
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}
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int count = cb->args[2];
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t_key key = cb->args[3];
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while (l) {
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cb->args[2] = l->key;
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rcu_read_lock();
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tp = rcu_dereference_rtnl(t->trie);
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while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
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if (fn_trie_dump_leaf(l, tb, skb, cb) < 0) {
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cb->args[3] = count;
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cb->args[3] = key;
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cb->args[2] = count;
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rcu_read_unlock();
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return -1;
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}
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++count;
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l = trie_nextleaf(l);
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key = l->key + 1;
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memset(&cb->args[4], 0,
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sizeof(cb->args) - 4*sizeof(cb->args[0]));
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/* stop loop if key wrapped back to 0 */
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if (key < l->key)
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break;
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}
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cb->args[3] = count;
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rcu_read_unlock();
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cb->args[3] = key;
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cb->args[2] = count;
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return skb->len;
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}
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@ -2186,31 +2186,46 @@ static const struct file_operations fib_trie_fops = {
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struct fib_route_iter {
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struct seq_net_private p;
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struct trie *main_trie;
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struct fib_table *main_tb;
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struct tnode *tnode;
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loff_t pos;
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t_key key;
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};
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static struct tnode *fib_route_get_idx(struct fib_route_iter *iter, loff_t pos)
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{
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struct tnode *l = NULL;
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struct trie *t = iter->main_trie;
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struct fib_table *tb = iter->main_tb;
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struct tnode *l, **tp = &iter->tnode;
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struct trie *t;
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t_key key;
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/* use cache location of last found key */
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if (iter->pos > 0 && pos >= iter->pos && (l = fib_find_node(t, iter->key)))
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/* use cache location of next-to-find key */
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if (iter->pos > 0 && pos >= iter->pos) {
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pos -= iter->pos;
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else {
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key = iter->key;
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} else {
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t = (struct trie *)tb->tb_data;
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iter->tnode = rcu_dereference_rtnl(t->trie);
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iter->pos = 0;
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l = trie_firstleaf(t);
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key = 0;
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}
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while (l && pos-- > 0) {
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while ((l = leaf_walk_rcu(tp, key)) != NULL) {
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key = l->key + 1;
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iter->pos++;
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l = trie_nextleaf(l);
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if (pos-- <= 0)
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break;
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l = NULL;
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/* handle unlikely case of a key wrap */
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if (!key)
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break;
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}
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if (l)
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iter->key = pos; /* remember it */
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iter->key = key; /* remember it */
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else
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iter->pos = 0; /* forget it */
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@ -2222,37 +2237,46 @@ static void *fib_route_seq_start(struct seq_file *seq, loff_t *pos)
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{
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struct fib_route_iter *iter = seq->private;
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struct fib_table *tb;
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struct trie *t;
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rcu_read_lock();
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tb = fib_get_table(seq_file_net(seq), RT_TABLE_MAIN);
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if (!tb)
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return NULL;
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iter->main_trie = (struct trie *) tb->tb_data;
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if (*pos == 0)
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return SEQ_START_TOKEN;
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else
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return fib_route_get_idx(iter, *pos - 1);
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iter->main_tb = tb;
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if (*pos != 0)
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return fib_route_get_idx(iter, *pos);
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t = (struct trie *)tb->tb_data;
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iter->tnode = rcu_dereference_rtnl(t->trie);
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iter->pos = 0;
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iter->key = 0;
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return SEQ_START_TOKEN;
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}
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static void *fib_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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struct fib_route_iter *iter = seq->private;
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struct tnode *l = v;
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struct tnode *l = NULL;
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t_key key = iter->key;
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++*pos;
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if (v == SEQ_START_TOKEN) {
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iter->pos = 0;
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l = trie_firstleaf(iter->main_trie);
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} else {
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/* only allow key of 0 for start of sequence */
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if ((v == SEQ_START_TOKEN) || key)
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l = leaf_walk_rcu(&iter->tnode, key);
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if (l) {
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iter->key = l->key + 1;
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iter->pos++;
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l = trie_nextleaf(l);
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} else {
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iter->pos = 0;
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}
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if (l)
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iter->key = l->key;
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else
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iter->pos = 0;
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return l;
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}
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