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422 lines
12 KiB
422 lines
12 KiB
![]()
10 years ago
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From: Alexander Duyck <alexander.h.duyck@redhat.com>
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Date: Wed, 31 Dec 2014 10:55:35 -0800
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Subject: [PATCH] fib_trie: Make leaf and tnode more uniform
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This change makes some fundamental changes to the way leaves and tnodes are
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constructed. The big differences are:
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1. Leaves now populate pos and bits indicating their full key size.
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2. Trie nodes now mask out their lower bits to be consistent with the leaf
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3. Both structures have been reordered so that rt_trie_node now consisists
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of a much larger region including the pos, bits, and rcu portions of
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the tnode structure.
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On 32b systems this will result in the leaf being 4B larger as the pos and
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bits values were added to a hole created by the key as it was only 4B in
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length.
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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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@@ -87,24 +87,38 @@
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typedef unsigned int t_key;
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-#define T_TNODE 0
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-#define T_LEAF 1
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-#define NODE_TYPE_MASK 0x1UL
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-#define NODE_TYPE(node) ((node)->parent & NODE_TYPE_MASK)
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+#define IS_TNODE(n) ((n)->bits)
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+#define IS_LEAF(n) (!(n)->bits)
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-#define IS_TNODE(n) (!(n->parent & T_LEAF))
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-#define IS_LEAF(n) (n->parent & T_LEAF)
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+struct tnode {
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+ t_key key;
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+ unsigned char bits; /* 2log(KEYLENGTH) bits needed */
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+ unsigned char pos; /* 2log(KEYLENGTH) bits needed */
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+ struct tnode __rcu *parent;
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+ union {
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+ struct rcu_head rcu;
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+ struct tnode *tnode_free;
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+ };
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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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+ struct rt_trie_node __rcu *child[0];
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+};
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struct rt_trie_node {
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- unsigned long parent;
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t_key key;
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+ unsigned char bits;
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+ unsigned char pos;
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+ struct tnode __rcu *parent;
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+ struct rcu_head rcu;
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};
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struct leaf {
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- unsigned long parent;
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t_key key;
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- struct hlist_head list;
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+ unsigned char bits;
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+ unsigned char pos;
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+ struct tnode __rcu *parent;
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struct rcu_head rcu;
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+ struct hlist_head list;
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};
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struct leaf_info {
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@@ -115,20 +129,6 @@ struct leaf_info {
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struct rcu_head rcu;
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};
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-struct tnode {
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- unsigned long parent;
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- t_key key;
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- unsigned char pos; /* 2log(KEYLENGTH) bits needed */
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- unsigned char bits; /* 2log(KEYLENGTH) bits needed */
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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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- union {
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- struct rcu_head rcu;
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- struct tnode *tnode_free;
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- };
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- struct rt_trie_node __rcu *child[0];
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-};
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-
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#ifdef CONFIG_IP_FIB_TRIE_STATS
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struct trie_use_stats {
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unsigned int gets;
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@@ -176,38 +176,27 @@ static const int sync_pages = 128;
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static struct kmem_cache *fn_alias_kmem __read_mostly;
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static struct kmem_cache *trie_leaf_kmem __read_mostly;
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-/*
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- * caller must hold RTNL
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- */
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-static inline struct tnode *node_parent(const struct rt_trie_node *node)
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-{
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- unsigned long parent;
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+/* caller must hold RTNL */
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+#define node_parent(n) rtnl_dereference((n)->parent)
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- parent = rcu_dereference_index_check(node->parent, lockdep_rtnl_is_held());
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+/* caller must hold RCU read lock or RTNL */
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+#define node_parent_rcu(n) rcu_dereference_rtnl((n)->parent)
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- return (struct tnode *)(parent & ~NODE_TYPE_MASK);
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-}
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-
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-/*
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- * caller must hold RCU read lock or RTNL
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- */
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-static inline struct tnode *node_parent_rcu(const struct rt_trie_node *node)
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+/* wrapper for rcu_assign_pointer */
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+static inline void node_set_parent(struct rt_trie_node *node, struct tnode *ptr)
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{
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- unsigned long parent;
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-
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- parent = rcu_dereference_index_check(node->parent, rcu_read_lock_held() ||
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- lockdep_rtnl_is_held());
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-
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- return (struct tnode *)(parent & ~NODE_TYPE_MASK);
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+ if (node)
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+ rcu_assign_pointer(node->parent, ptr);
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}
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-/* Same as rcu_assign_pointer
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- * but that macro() assumes that value is a pointer.
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+#define NODE_INIT_PARENT(n, p) RCU_INIT_POINTER((n)->parent, p)
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+
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+/* This provides us with the number of children in this node, in the case of a
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+ * leaf this will return 0 meaning none of the children are accessible.
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*/
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-static inline void node_set_parent(struct rt_trie_node *node, struct tnode *ptr)
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+static inline int tnode_child_length(const struct tnode *tn)
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{
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- smp_wmb();
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- node->parent = (unsigned long)ptr | NODE_TYPE(node);
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+ return (1ul << tn->bits) & ~(1ul);
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}
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/*
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@@ -215,7 +204,7 @@ static inline void node_set_parent(struc
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*/
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static inline struct rt_trie_node *tnode_get_child(const struct tnode *tn, unsigned int i)
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{
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- BUG_ON(i >= 1U << tn->bits);
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+ BUG_ON(i >= tnode_child_length(tn));
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return rtnl_dereference(tn->child[i]);
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}
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@@ -225,16 +214,11 @@ static inline struct rt_trie_node *tnode
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*/
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static inline struct rt_trie_node *tnode_get_child_rcu(const struct tnode *tn, unsigned int i)
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{
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- BUG_ON(i >= 1U << tn->bits);
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+ BUG_ON(i >= tnode_child_length(tn));
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return rcu_dereference_rtnl(tn->child[i]);
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}
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-static inline int tnode_child_length(const struct tnode *tn)
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-{
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- return 1 << tn->bits;
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-}
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-
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static inline t_key mask_pfx(t_key k, unsigned int l)
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{
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return (l == 0) ? 0 : k >> (KEYLENGTH-l) << (KEYLENGTH-l);
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@@ -336,11 +320,6 @@ static inline int tkey_mismatch(t_key a,
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*/
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-static inline void check_tnode(const struct tnode *tn)
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-{
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- WARN_ON(tn && tn->pos+tn->bits > 32);
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-}
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-
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static const int halve_threshold = 25;
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static const int inflate_threshold = 50;
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static const int halve_threshold_root = 15;
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@@ -426,11 +405,20 @@ static void tnode_free_flush(void)
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}
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}
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-static struct leaf *leaf_new(void)
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+static struct leaf *leaf_new(t_key key)
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{
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struct leaf *l = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
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if (l) {
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- l->parent = T_LEAF;
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+ l->parent = NULL;
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+ /* set key and pos to reflect full key value
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+ * any trailing zeros in the key should be ignored
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+ * as the nodes are searched
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+ */
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+ l->key = key;
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+ l->pos = KEYLENGTH;
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+ /* set bits to 0 indicating we are not a tnode */
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+ l->bits = 0;
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+
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INIT_HLIST_HEAD(&l->list);
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}
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return l;
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@@ -451,12 +439,16 @@ static struct tnode *tnode_new(t_key key
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{
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size_t sz = sizeof(struct tnode) + (sizeof(struct rt_trie_node *) << bits);
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struct tnode *tn = tnode_alloc(sz);
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+ unsigned int shift = pos + bits;
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+
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+ /* verify bits and pos their msb bits clear and values are valid */
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+ BUG_ON(!bits || (shift > KEYLENGTH));
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if (tn) {
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- tn->parent = T_TNODE;
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+ tn->parent = NULL;
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tn->pos = pos;
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tn->bits = bits;
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- tn->key = key;
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+ tn->key = mask_pfx(key, pos);
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tn->full_children = 0;
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tn->empty_children = 1<<bits;
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}
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@@ -473,10 +465,7 @@ static struct tnode *tnode_new(t_key key
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static inline int tnode_full(const struct tnode *tn, const struct rt_trie_node *n)
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{
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- if (n == NULL || IS_LEAF(n))
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- return 0;
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-
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- return ((struct tnode *) n)->pos == tn->pos + tn->bits;
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+ return n && IS_TNODE(n) && (n->pos == (tn->pos + tn->bits));
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}
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static inline void put_child(struct tnode *tn, int i,
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@@ -514,8 +503,7 @@ static void tnode_put_child_reorg(struct
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else if (!wasfull && isfull)
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tn->full_children++;
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- if (n)
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- node_set_parent(n, tn);
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+ node_set_parent(n, tn);
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rcu_assign_pointer(tn->child[i], n);
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}
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@@ -523,7 +511,7 @@ static void tnode_put_child_reorg(struct
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#define MAX_WORK 10
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static struct rt_trie_node *resize(struct trie *t, struct tnode *tn)
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{
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- int i;
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+ struct rt_trie_node *n = NULL;
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struct tnode *old_tn;
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int inflate_threshold_use;
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int halve_threshold_use;
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@@ -536,12 +524,11 @@ static struct rt_trie_node *resize(struc
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tn, inflate_threshold, halve_threshold);
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/* No children */
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- if (tn->empty_children == tnode_child_length(tn)) {
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- tnode_free_safe(tn);
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- return NULL;
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- }
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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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+ 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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@@ -607,11 +594,9 @@ static struct rt_trie_node *resize(struc
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*
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*/
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- check_tnode(tn);
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-
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/* Keep root node larger */
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- if (!node_parent((struct rt_trie_node *)tn)) {
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+ if (!node_parent(tn)) {
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inflate_threshold_use = inflate_threshold_root;
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halve_threshold_use = halve_threshold_root;
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} else {
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@@ -637,8 +622,6 @@ static struct rt_trie_node *resize(struc
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}
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}
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- check_tnode(tn);
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-
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/* Return if at least one inflate is run */
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if (max_work != MAX_WORK)
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return (struct rt_trie_node *) tn;
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@@ -666,21 +649,16 @@ static struct rt_trie_node *resize(struc
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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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+ 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 = 0; i < tnode_child_length(tn); i++) {
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- struct rt_trie_node *n;
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-
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- n = rtnl_dereference(tn->child[i]);
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- if (!n)
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- continue;
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-
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- /* compress one level */
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-
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- node_set_parent(n, NULL);
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- tnode_free_safe(tn);
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- return n;
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- }
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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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+ node_set_parent(n, NULL);
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+ tnode_free_safe(tn);
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+ return n;
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}
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return (struct rt_trie_node *) tn;
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}
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@@ -760,8 +738,7 @@ static struct tnode *inflate(struct trie
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/* A leaf or an internal node with skipped bits */
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- if (IS_LEAF(node) || ((struct tnode *) node)->pos >
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- tn->pos + tn->bits - 1) {
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+ if (IS_LEAF(node) || (node->pos > (tn->pos + tn->bits - 1))) {
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put_child(tn,
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tkey_extract_bits(node->key, oldtnode->pos, oldtnode->bits + 1),
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node);
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@@ -958,11 +935,9 @@ fib_find_node(struct trie *t, u32 key)
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pos = 0;
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n = rcu_dereference_rtnl(t->trie);
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- while (n != NULL && NODE_TYPE(n) == T_TNODE) {
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+ while (n && IS_TNODE(n)) {
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tn = (struct tnode *) n;
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- check_tnode(tn);
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-
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if (tkey_sub_equals(tn->key, pos, tn->pos-pos, key)) {
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pos = tn->pos + tn->bits;
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n = tnode_get_child_rcu(tn,
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@@ -988,7 +963,7 @@ static void trie_rebalance(struct trie *
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key = tn->key;
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- while (tn != NULL && (tp = node_parent((struct rt_trie_node *)tn)) != NULL) {
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+ while (tn != NULL && (tp = node_parent(tn)) != NULL) {
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cindex = tkey_extract_bits(key, tp->pos, tp->bits);
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wasfull = tnode_full(tp, tnode_get_child(tp, cindex));
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tn = (struct tnode *)resize(t, tn);
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@@ -996,7 +971,7 @@ static void trie_rebalance(struct trie *
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tnode_put_child_reorg(tp, cindex,
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(struct rt_trie_node *)tn, wasfull);
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- tp = node_parent((struct rt_trie_node *) tn);
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+ tp = node_parent(tn);
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if (!tp)
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rcu_assign_pointer(t->trie, (struct rt_trie_node *)tn);
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@@ -1048,11 +1023,9 @@ static struct list_head *fib_insert_node
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* If it doesn't, we need to replace it with a T_TNODE.
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*/
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- while (n != NULL && NODE_TYPE(n) == T_TNODE) {
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+ while (n && IS_TNODE(n)) {
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tn = (struct tnode *) n;
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- check_tnode(tn);
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-
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if (tkey_sub_equals(tn->key, pos, tn->pos-pos, key)) {
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tp = tn;
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pos = tn->pos + tn->bits;
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@@ -1087,12 +1060,11 @@ static struct list_head *fib_insert_node
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insert_leaf_info(&l->list, li);
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goto done;
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}
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- l = leaf_new();
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+ l = leaf_new(key);
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if (!l)
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return NULL;
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- l->key = key;
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li = leaf_info_new(plen);
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if (!li) {
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@@ -1569,7 +1541,7 @@ backtrace:
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if (chopped_off <= pn->bits) {
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cindex &= ~(1 << (chopped_off-1));
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} else {
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- struct tnode *parent = node_parent_rcu((struct rt_trie_node *) pn);
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+ struct tnode *parent = node_parent_rcu(pn);
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||
|
if (!parent)
|
||
|
goto failed;
|
||
|
|
||
|
@@ -1597,7 +1569,7 @@ EXPORT_SYMBOL_GPL(fib_table_lookup);
|
||
|
*/
|
||
|
static void trie_leaf_remove(struct trie *t, struct leaf *l)
|
||
|
{
|
||
|
- struct tnode *tp = node_parent((struct rt_trie_node *) l);
|
||
|
+ struct tnode *tp = node_parent(l);
|
||
|
|
||
|
pr_debug("entering trie_leaf_remove(%p)\n", l);
|
||
|
|
||
![]()
10 years ago
|
@@ -2374,7 +2346,7 @@ static int fib_trie_seq_show(struct seq_
|
||
![]()
10 years ago
|
|
||
|
if (IS_TNODE(n)) {
|
||
|
struct tnode *tn = (struct tnode *) n;
|
||
|
- __be32 prf = htonl(mask_pfx(tn->key, tn->pos));
|
||
|
+ __be32 prf = htonl(tn->key);
|
||
|
|
||
|
seq_indent(seq, iter->depth-1);
|
||
|
seq_printf(seq, " +-- %pI4/%d %d %d %d\n",
|