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Date: Tue, 22 Jan 2008 15:37:39 -0800
From: Stephen Hemminger <shemminger@...ux-foundation.org>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: [IPV4 6/9] fib_trie: iterator recode
Remove the complex loop structure of nextleaf() andreplace it with a
simpler tree walker. This improves the performance and is much
cleaner.
Signed-off-by: Stephen Hemminger <shemminger@...tta.com>
--- a/net/ipv4/fib_trie.c 2008-01-22 09:52:46.000000000 -0800
+++ b/net/ipv4/fib_trie.c 2008-01-22 12:58:59.000000000 -0800
@@ -1708,64 +1708,65 @@ static int trie_flush_leaf(struct trie *
return found;
}
-/* rcu_read_lock needs to be hold by caller from readside */
-
-static struct leaf *nextleaf(struct trie *t, struct leaf *thisleaf)
+/*
+ * Scan for the next right leaf starting at node p->child[idx]
+ * Since we have back pointer, no recursion necessary.
+ */
+static struct leaf *leaf_walk_rcu(struct tnode *p, struct node *c)
{
- struct node *c = (struct node *) thisleaf;
- struct tnode *p;
- int idx;
- struct node *trie = rcu_dereference(t->trie);
-
- if (c == NULL) {
- if (trie == NULL)
- return NULL;
-
- if (IS_LEAF(trie)) /* trie w. just a leaf */
- return (struct leaf *) trie;
-
- p = (struct tnode *)trie; /* Start */
- } else
- p = node_parent_rcu(c);
+ do {
+ t_key idx;
- while (p) {
- int pos, last;
-
- /* Find the next child of the parent */
if (c)
- pos = 1 + tkey_extract_bits(c->key, p->pos, p->bits);
+ idx = tkey_extract_bits(c->key, p->pos, p->bits) + 1;
else
- pos = 0;
-
- last = 1 << p->bits;
- for (idx = pos; idx < last ; idx++) {
- c = rcu_dereference(p->child[idx]);
+ idx = 0;
+ while (idx < 1u << p->bits) {
+ c = tnode_get_child_rcu(p, idx++);
if (!c)
continue;
- /* Decend if tnode */
- while (IS_TNODE(c)) {
- p = (struct tnode *) c;
- idx = 0;
-
- /* Rightmost non-NULL branch */
- if (p && IS_TNODE(p))
- while (!(c = rcu_dereference(p->child[idx]))
- && idx < (1<<p->bits)) idx++;
-
- /* Done with this tnode? */
- if (idx >= (1 << p->bits) || !c)
- goto up;
+ if (IS_LEAF(c)) {
+ prefetch(p->child[idx]);
+ return (struct leaf *) c;
}
- return (struct leaf *) c;
+
+ /* Rescan start scanning in new node */
+ p = (struct tnode *) c;
+ idx = 0;
}
-up:
- /* No more children go up one step */
+
+ /* Node empty, walk back up to parent */
c = (struct node *) p;
- p = node_parent_rcu(c);
- }
- return NULL; /* Ready. Root of trie */
+ } while ( (p = node_parent_rcu(c)) != NULL);
+
+ return NULL; /* Root of trie */
+}
+
+
+static struct leaf *trie_firstleaf(struct trie *t)
+{
+ struct tnode *n = (struct tnode *) rcu_dereference(t->trie);
+
+ if (!n)
+ return NULL;
+
+ if (IS_LEAF(n)) /* trie is just a leaf */
+ return (struct leaf *) n;
+
+ return leaf_walk_rcu(n, NULL);
+}
+
+static struct leaf *trie_nextleaf(struct leaf *l)
+{
+ struct node *c = (struct node *) l;
+ struct tnode *p = node_parent(c);
+
+ if (!p)
+ return NULL; /* trie with just one leaf */
+
+ return leaf_walk_rcu(p, c);
}
/*
@@ -1775,9 +1776,9 @@ static int fn_trie_flush(struct fib_tabl
{
struct trie *t = (struct trie *) tb->tb_data;
struct leaf *ll = NULL, *l = NULL;
- int found = 0, h;
+ int found = 0;
- for (h = 0; (l = nextleaf(t, l)) != NULL; h++) {
+ for (l = trie_firstleaf(t); l; l = trie_nextleaf(l)) {
found += trie_flush_leaf(t, l);
if (ll && hlist_empty(&ll->list))
@@ -1884,7 +1885,6 @@ static int fn_trie_dump_fa(t_key key, in
i++;
continue;
}
- BUG_ON(!fa->fa_info);
if (fib_dump_info(skb, NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq,
@@ -1913,8 +1913,9 @@ static int fn_trie_dump_plen(struct trie
struct leaf *l = NULL;
s_h = cb->args[3];
+ h = 0;
- for (h = 0; (l = nextleaf(t, l)) != NULL; h++) {
+ for (l = trie_firstleaf(t); l != NULL; h++, l = trie_nextleaf(l)) {
if (h < s_h)
continue;
if (h > s_h)
--
Stephen Hemminger <stephen.hemminger@...tta.com>
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