| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20141222174136.1119.15995.stgit@ahduyck-vm-fedora20>
Date: Mon, 22 Dec 2014 09:41:36 -0800
From: Alexander Duyck <alexander.h.duyck@...hat.com>
To: netdev@...r.kernel.org
Subject: [RFC PATCH 07/17] fib_trie: Optimize fib_table_insert
This patch updates the fib_table_insert function to take advantage of the
changes made to improve the performance of fib_table_lookup. As a result
the code should be smaller and run faster then the original.
Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>
---
net/ipv4/fib_trie.c | 196 ++++++++++++++++++---------------------------------
1 file changed, 71 insertions(+), 125 deletions(-)
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index c182143..969ecf3 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -222,31 +222,6 @@ static inline t_key tkey_extract_bits(t_key a, unsigned int offset, unsigned int
return 0;
}
-static inline int tkey_equals(t_key a, t_key b)
-{
- return a == b;
-}
-
-static inline int tkey_sub_equals(t_key a, int offset, int bits, t_key b)
-{
- if (bits == 0 || offset >= KEYLENGTH)
- return 1;
- bits = bits > KEYLENGTH ? KEYLENGTH : bits;
- return ((a ^ b) << offset) >> (KEYLENGTH - bits) == 0;
-}
-
-static inline int tkey_mismatch(t_key a, int offset, t_key b)
-{
- t_key diff = a ^ b;
- int i = offset;
-
- if (!diff)
- return 0;
- while ((diff << i) >> (KEYLENGTH-1) == 0)
- i++;
- return i;
-}
-
/*
To understand this stuff, an understanding of keys and all their bits is
necessary. Every node in the trie has a key associated with it, but not
@@ -485,6 +460,15 @@ static void tnode_put_child_reorg(struct tnode *tn, int i, struct tnode *n,
rcu_assign_pointer(tn->child[i], n);
}
+static void put_child_root(struct tnode *tp, struct trie *t,
+ t_key key, struct tnode *n)
+{
+ if (tp)
+ put_child(tp, get_index(key, tp), n);
+ else
+ rcu_assign_pointer(t->trie, n);
+}
+
#define MAX_WORK 10
static struct tnode *resize(struct trie *t, struct tnode *tn)
{
@@ -959,138 +943,100 @@ static void trie_rebalance(struct trie *t, struct tnode *tn)
static struct list_head *fib_insert_node(struct trie *t, u32 key, int plen)
{
- int pos, newpos;
- struct tnode *tp = NULL, *tn = NULL;
- struct tnode *n;
- struct tnode *l;
- int missbit;
struct list_head *fa_head = NULL;
+ struct tnode *l, *n, *tp = NULL;
struct leaf_info *li;
- t_key cindex;
- pos = 0;
+ li = leaf_info_new(plen);
+ if (!li)
+ return NULL;
+ fa_head = &li->falh;
+
n = rtnl_dereference(t->trie);
/* If we point to NULL, stop. Either the tree is empty and we should
* just put a new leaf in if, or we have reached an empty child slot,
* and we should just put our new leaf in that.
- * If we point to a T_TNODE, check if it matches our key. Note that
- * a T_TNODE might be skipping any number of bits - its 'pos' need
- * not be the parent's 'pos'+'bits'!
- *
- * If it does match the current key, get pos/bits from it, extract
- * the index from our key, push the T_TNODE and walk the tree.
- *
- * If it doesn't, we have to replace it with a new T_TNODE.
*
- * If we point to a T_LEAF, it might or might not have the same key
- * as we do. If it does, just change the value, update the T_LEAF's
- * value, and return it.
- * If it doesn't, we need to replace it with a T_TNODE.
+ * If we hit a node with a key that does't match then we should stop
+ * and create a new tnode to replace that node and insert ourselves
+ * and the other node into the new tnode.
*/
+ while (n) {
+ unsigned long index = get_index(key, n);
- while (n && IS_TNODE(n)) {
- if (tkey_sub_equals(n->key, pos, n->pos-pos, key)) {
- tp = n;
- pos = n->pos + n->bits;
- n = tnode_get_child(n,
- tkey_extract_bits(key,
- n->pos,
- n->bits));
-
- BUG_ON(n && node_parent(n) != tp);
- } else
+ /* This bit of code is a bit tricky but it combines multiple
+ * checks into a single check. The prefix consists of the
+ * prefix plus zeros for the "bits" in the prefix. The index
+ * is the difference between the key and this value. From
+ * this we can actually derive several pieces of data.
+ * if !(index >> bits)
+ * we know the value is child index
+ * else
+ * we have a mismatch in skip bits and failed
+ */
+ if (index >> n->bits)
break;
- }
-
- /*
- * n ----> NULL, LEAF or TNODE
- *
- * tp is n's (parent) ----> NULL or TNODE
- */
-
- BUG_ON(tp && IS_LEAF(tp));
-
- /* Case 1: n is a leaf. Compare prefixes */
-
- if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key)) {
- li = leaf_info_new(plen);
- if (!li)
- return NULL;
+ /* we have found a leaf. Prefixes have already been compared */
+ if (IS_LEAF(n)) {
+ /* Case 1: n is a leaf, and prefixes match*/
+ insert_leaf_info(&n->list, li);
+ return fa_head;
+ }
- fa_head = &li->falh;
- insert_leaf_info(&n->list, li);
- goto done;
+ tp = n;
+ n = rcu_dereference_rtnl(n->child[index]);
}
- l = leaf_new(key);
-
- if (!l)
- return NULL;
-
- li = leaf_info_new(plen);
- if (!li) {
- node_free(l);
+ l = leaf_new(key);
+ if (!l) {
+ free_leaf_info(li);
return NULL;
}
- fa_head = &li->falh;
insert_leaf_info(&l->list, li);
- if (t->trie && n == NULL) {
- /* Case 2: n is NULL, and will just insert a new leaf */
-
- node_set_parent(l, tp);
-
- cindex = tkey_extract_bits(key, tp->pos, tp->bits);
- put_child(tp, cindex, l);
- } else {
- /* Case 3: n is a LEAF or a TNODE and the key doesn't match. */
- /*
- * Add a new tnode here
- * first tnode need some special handling
- */
+ /* Case 2: n is a LEAF or a TNODE and the key doesn't match.
+ *
+ * Add a new tnode here
+ * first tnode need some special handling
+ * leaves us in position for handling as case 3
+ */
+ if (n) {
+ struct tnode *tn;
+ int newpos;
- if (n) {
- pos = tp ? tp->pos+tp->bits : 0;
- newpos = tkey_mismatch(key, pos, n->key);
- tn = tnode_new(n->key, newpos, 1);
- } else {
- newpos = 0;
- tn = tnode_new(key, newpos, 1); /* First tnode */
- }
+ newpos = KEYLENGTH - __fls(n->key ^ key) - 1;
+ tn = tnode_new(key, newpos, 1);
if (!tn) {
free_leaf_info(li);
node_free(l);
return NULL;
}
- node_set_parent(tn, tp);
-
- missbit = tkey_extract_bits(key, newpos, 1);
- put_child(tn, missbit, l);
- put_child(tn, 1-missbit, n);
+ /* initialize routes out of node */
+ NODE_INIT_PARENT(tn, tp);
+ put_child(tn, get_index(key, tn) ^ 1, n);
- if (tp) {
- cindex = tkey_extract_bits(key, tp->pos, tp->bits);
- put_child(tp, cindex, tn);
- } else {
- rcu_assign_pointer(t->trie, tn);
- }
+ /* start adding routes into the node */
+ put_child_root(tp, t, key, tn);
+ node_set_parent(n, tn);
+ /* parent now has a NULL spot where the leaf can go */
tp = tn;
}
- if (tp && tp->pos + tp->bits > 32)
- pr_warn("fib_trie tp=%p pos=%d, bits=%d, key=%0x plen=%d\n",
- tp, tp->pos, tp->bits, key, plen);
-
- /* Rebalance the trie */
+ /* Case 3: n is NULL, and will just insert a new leaf */
+ if (tp) {
+ NODE_INIT_PARENT(l, tp);
+ put_child(tp, get_index(key, tp), l);
+ trie_rebalance(t, tp);
+ } else {
+ rcu_assign_pointer(t->trie, l);
+ }
- trie_rebalance(t, tp);
-done:
return fa_head;
}
@@ -1466,11 +1412,11 @@ static void trie_leaf_remove(struct trie *t, struct tnode *l)
pr_debug("entering trie_leaf_remove(%p)\n", l);
if (tp) {
- t_key cindex = tkey_extract_bits(l->key, tp->pos, tp->bits);
- put_child(tp, cindex, NULL);
+ put_child(tp, get_index(l->key, tp), NULL);
trie_rebalance(t, tp);
- } else
+ } else {
RCU_INIT_POINTER(t->trie, NULL);
+ }
node_free(l);
}
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists