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fib_trie: Optimize fib_table_insert

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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@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2014-12-31 10:56:06 -08:00 committed by David S. Miller
parent 939afb0657
commit 836a0123c9
1 changed files with 79 additions and 133 deletions
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212
net/ipv4/fib_trie.c
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@ -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
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;
fa_head = &li->falh;
insert_leaf_info(&n->list, li);
goto done;
}
l = leaf_new(key);
if (!l)
return NULL;
li = leaf_info_new(plen);
if (!li) {
node_free(l);
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
/* 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;
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 */
/* 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;
}
tp = n;
n = rcu_dereference_rtnl(n->child[index]);
}
l = leaf_new(key);
if (!l) {
free_leaf_info(li);
return NULL;
}
insert_leaf_info(&l->list, li);
/* 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;
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);
/* initialize routes out of node */
NODE_INIT_PARENT(tn, tp);
put_child(tn, get_index(key, tn) ^ 1, n);
missbit = tkey_extract_bits(key, newpos, 1);
put_child(tn, missbit, l);
put_child(tn, 1-missbit, 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);
/* 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);
}
/* Rebalance the trie */
trie_rebalance(t, tp);
done:
return fa_head;
}
@ -1470,11 +1416,11 @@ 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);
}