redonkable/alistair23-linux
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fib_trie: Optimize fib_find_node

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This patch makes use of the same features I made use of for
fib_table_lookup to streamline fib_find_node.  The resultant code should be
smaller and run faster than the original.

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 2014-12-31 10:56:00 -08:00 committed by David S. Miller
parent 9f9e636d4f
commit 939afb0657
1 changed files with 21 additions and 15 deletions
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36
net/ipv4/fib_trie.c
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@ -892,28 +892,34 @@ static void insert_leaf_info(struct hlist_head *head, struct leaf_info *new)
}
/* rcu_read_lock needs to be hold by caller from readside */
static struct tnode *fib_find_node(struct trie *t, u32 key)
{
struct tnode *n = rcu_dereference_rtnl(t->trie);
int pos = 0;
while (n && IS_TNODE(n)) {
if (tkey_sub_equals(n->key, pos, n->pos-pos, key)) {
pos = n->pos + n->bits;
n = tnode_get_child_rcu(n,
tkey_extract_bits(key,
n->pos,
n->bits));
} else
while (n) {
unsigned long index = get_index(key, n);
/* 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 cindex. 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 cindex
* else
* we have a mismatch in skip bits and failed
*/
if (index >> n->bits)
return NULL;
/* we have found a leaf. Prefixes have already been compared */
if (IS_LEAF(n))
break;
n = rcu_dereference_rtnl(n->child[index]);
}
/* Case we have found a leaf. Compare prefixes */
if (n != NULL && IS_LEAF(n) && tkey_equals(key, n->key))
return n;
return NULL;
return n;
}
static void trie_rebalance(struct trie *t, struct tnode *tn)