mirror of https://github.com/hak5/openwrt-owl.git
207 lines
6.0 KiB
Diff
207 lines
6.0 KiB
Diff
From: Alexander Duyck <alexander.h.duyck@redhat.com>
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Date: Thu, 22 Jan 2015 15:51:26 -0800
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Subject: [PATCH] fib_trie: Add collapse() and should_collapse() to resize
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This patch really does two things.
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First it pulls the logic for determining if we should collapse one node out
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of the tree and the actual code doing the collapse into a separate pair of
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functions. This helps to make the changes to these areas more readable.
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Second it encodes the upper 32b of the empty_children value onto the
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full_children value in the case of bits == KEYLENGTH. By doing this we are
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able to handle the case of a 32b node where empty_children would appear to
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be 0 when it was actually 1ul << 32.
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Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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--- a/net/ipv4/fib_trie.c
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+++ b/net/ipv4/fib_trie.c
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@@ -83,7 +83,8 @@
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#define MAX_STAT_DEPTH 32
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-#define KEYLENGTH (8*sizeof(t_key))
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+#define KEYLENGTH (8*sizeof(t_key))
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+#define KEY_MAX ((t_key)~0)
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typedef unsigned int t_key;
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@@ -102,8 +103,8 @@ struct tnode {
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union {
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/* The fields in this struct are valid if bits > 0 (TNODE) */
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struct {
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- unsigned int full_children; /* KEYLENGTH bits needed */
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- unsigned int empty_children; /* KEYLENGTH bits needed */
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+ t_key empty_children; /* KEYLENGTH bits needed */
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+ t_key full_children; /* KEYLENGTH bits needed */
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struct tnode __rcu *child[0];
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};
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/* This list pointer if valid if bits == 0 (LEAF) */
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@@ -302,6 +303,16 @@ static struct tnode *tnode_alloc(size_t
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return vzalloc(size);
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}
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+static inline void empty_child_inc(struct tnode *n)
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+{
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+ ++n->empty_children ? : ++n->full_children;
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+}
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+
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+static inline void empty_child_dec(struct tnode *n)
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+{
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+ n->empty_children-- ? : n->full_children--;
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+}
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+
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static struct tnode *leaf_new(t_key key)
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{
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struct tnode *l = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
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@@ -335,7 +346,7 @@ static struct leaf_info *leaf_info_new(i
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static struct tnode *tnode_new(t_key key, int pos, int bits)
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{
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- size_t sz = offsetof(struct tnode, child[1 << bits]);
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+ size_t sz = offsetof(struct tnode, child[1ul << bits]);
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struct tnode *tn = tnode_alloc(sz);
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unsigned int shift = pos + bits;
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@@ -348,8 +359,10 @@ static struct tnode *tnode_new(t_key key
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tn->pos = pos;
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tn->bits = bits;
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tn->key = (shift < KEYLENGTH) ? (key >> shift) << shift : 0;
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- tn->full_children = 0;
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- tn->empty_children = 1<<bits;
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+ if (bits == KEYLENGTH)
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+ tn->full_children = 1;
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+ else
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+ tn->empty_children = 1ul << bits;
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}
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pr_debug("AT %p s=%zu %zu\n", tn, sizeof(struct tnode),
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@@ -375,11 +388,11 @@ static void put_child(struct tnode *tn,
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BUG_ON(i >= tnode_child_length(tn));
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- /* update emptyChildren */
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+ /* update emptyChildren, overflow into fullChildren */
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if (n == NULL && chi != NULL)
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- tn->empty_children++;
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- else if (n != NULL && chi == NULL)
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- tn->empty_children--;
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+ empty_child_inc(tn);
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+ if (n != NULL && chi == NULL)
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+ empty_child_dec(tn);
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/* update fullChildren */
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wasfull = tnode_full(tn, chi);
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@@ -630,6 +643,24 @@ static int halve(struct trie *t, struct
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return 0;
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}
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+static void collapse(struct trie *t, struct tnode *oldtnode)
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+{
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+ struct tnode *n, *tp;
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+ unsigned long i;
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+
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+ /* scan the tnode looking for that one child that might still exist */
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+ for (n = NULL, i = tnode_child_length(oldtnode); !n && i;)
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+ n = tnode_get_child(oldtnode, --i);
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+
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+ /* compress one level */
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+ tp = node_parent(oldtnode);
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+ put_child_root(tp, t, oldtnode->key, n);
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+ node_set_parent(n, tp);
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+
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+ /* drop dead node */
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+ node_free(oldtnode);
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+}
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+
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static unsigned char update_suffix(struct tnode *tn)
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{
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unsigned char slen = tn->pos;
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@@ -729,10 +760,12 @@ static bool should_inflate(const struct
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/* Keep root node larger */
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threshold *= tp ? inflate_threshold : inflate_threshold_root;
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- used += tn->full_children;
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used -= tn->empty_children;
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+ used += tn->full_children;
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- return tn->pos && ((50 * used) >= threshold);
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+ /* if bits == KEYLENGTH then pos = 0, and will fail below */
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+
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+ return (used > 1) && tn->pos && ((50 * used) >= threshold);
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}
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static bool should_halve(const struct tnode *tp, const struct tnode *tn)
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@@ -744,13 +777,29 @@ static bool should_halve(const struct tn
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threshold *= tp ? halve_threshold : halve_threshold_root;
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used -= tn->empty_children;
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- return (tn->bits > 1) && ((100 * used) < threshold);
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+ /* if bits == KEYLENGTH then used = 100% on wrap, and will fail below */
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+
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+ return (used > 1) && (tn->bits > 1) && ((100 * used) < threshold);
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+}
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+
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+static bool should_collapse(const struct tnode *tn)
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+{
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+ unsigned long used = tnode_child_length(tn);
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+
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+ used -= tn->empty_children;
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+
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+ /* account for bits == KEYLENGTH case */
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+ if ((tn->bits == KEYLENGTH) && tn->full_children)
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+ used -= KEY_MAX;
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+
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+ /* One child or none, time to drop us from the trie */
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+ return used < 2;
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}
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#define MAX_WORK 10
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static void resize(struct trie *t, struct tnode *tn)
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{
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- struct tnode *tp = node_parent(tn), *n = NULL;
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+ struct tnode *tp = node_parent(tn);
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struct tnode __rcu **cptr;
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int max_work = MAX_WORK;
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@@ -764,14 +813,6 @@ static void resize(struct trie *t, struc
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cptr = tp ? &tp->child[get_index(tn->key, tp)] : &t->trie;
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BUG_ON(tn != rtnl_dereference(*cptr));
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- /* No children */
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- if (tn->empty_children > (tnode_child_length(tn) - 1))
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- goto no_children;
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-
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- /* One child */
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- if (tn->empty_children == (tnode_child_length(tn) - 1))
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- goto one_child;
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-
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/* Double as long as the resulting node has a number of
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* nonempty nodes that are above the threshold.
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*/
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@@ -807,19 +848,8 @@ static void resize(struct trie *t, struc
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}
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/* Only one child remains */
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- if (tn->empty_children == (tnode_child_length(tn) - 1)) {
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- unsigned long i;
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-one_child:
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- for (i = tnode_child_length(tn); !n && i;)
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- n = tnode_get_child(tn, --i);
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-no_children:
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- /* compress one level */
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- put_child_root(tp, t, tn->key, n);
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- node_set_parent(n, tp);
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-
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- /* drop dead node */
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- tnode_free_init(tn);
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- tnode_free(tn);
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+ if (should_collapse(tn)) {
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+ collapse(t, tn);
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return;
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}
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