tipc: Convert node object array to a hash table

Replaces the dynamically allocated array of pointers to the cluster's
node objects with a static hash table. Hash collisions are resolved
using chaining, with a typical hash chain having only a single node,
to avoid degrading performance during processing of incoming packets.
The conversion to a hash table reduces the memory requirements for
TIPC's node table to approximately the same size it had prior to
the previous commit.

In addition to the hash table itself, TIPC now also maintains a
linked list for the node objects, sorted by ascending network address.
This list allows TIPC to continue sending responses to user space
applications that request node and link information in sorted order.
The list also improves performance when name table update messages are
sent by making it easier to identify the nodes that must be notified.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

1 files changed, 43 insertions, 27 deletions

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 64976f2..22aeb2b 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -44,9 +44,31 @@ static void node_established_contact(struct tipc_node *n_ptr);
 
 static DEFINE_SPINLOCK(node_create_lock);
 
+static struct hlist_head node_htable[NODE_HTABLE_SIZE];
+LIST_HEAD(tipc_node_list);
+static u32 tipc_num_nodes;
 u32 tipc_own_tag;
 
 /**
+ * tipc_node_find - locate specified node object, if it exists
+ */
+
+struct tipc_node *tipc_node_find(u32 addr)
+{
+	struct tipc_node *node;
+	struct hlist_node *pos;
+
+	if (unlikely(!in_own_cluster(addr)))
+		return NULL;
+
+	hlist_for_each_entry(node, pos, &node_htable[tipc_hashfn(addr)], hash) {
+		if (node->addr == addr)
+			return node;
+	}
+	return NULL;
+}
+
+/**
  * tipc_node_create - create neighboring node
  *
  * Currently, this routine is called by neighbor discovery code, which holds
@@ -58,8 +80,7 @@ u32 tipc_own_tag;
 
 struct tipc_node *tipc_node_create(u32 addr)
 {
-	struct tipc_node *n_ptr;
-	u32 n_num;
+	struct tipc_node *n_ptr, *temp_node;
 
 	spin_lock_bh(&node_create_lock);
 
@@ -78,12 +99,19 @@ struct tipc_node *tipc_node_create(u32 addr)
 
 	n_ptr->addr = addr;
 	spin_lock_init(&n_ptr->lock);
+	INIT_HLIST_NODE(&n_ptr->hash);
+	INIT_LIST_HEAD(&n_ptr->list);
 	INIT_LIST_HEAD(&n_ptr->nsub);
 
-	n_num = tipc_node(addr);
-	tipc_nodes[n_num] = n_ptr;
-	if (n_num > tipc_highest_node)
-		tipc_highest_node = n_num;
+	hlist_add_head(&n_ptr->hash, &node_htable[tipc_hashfn(addr)]);
+
+	list_for_each_entry(temp_node, &tipc_node_list, list) {
+		if (n_ptr->addr < temp_node->addr)
+			break;
+	}
+	list_add_tail(&n_ptr->list, &temp_node->list);
+
+	tipc_num_nodes++;
 
 	spin_unlock_bh(&node_create_lock);
 	return n_ptr;
@@ -91,18 +119,11 @@ struct tipc_node *tipc_node_create(u32 addr)
 
 void tipc_node_delete(struct tipc_node *n_ptr)
 {
-	u32 n_num;
-
-	if (!n_ptr)
-		return;
-
-	n_num = tipc_node(n_ptr->addr);
-	tipc_nodes[n_num] = NULL;
+	list_del(&n_ptr->list);
+	hlist_del(&n_ptr->hash);
 	kfree(n_ptr);
 
-	while (!tipc_nodes[tipc_highest_node])
-		if (--tipc_highest_node == 0)
-			break;
+	tipc_num_nodes--;
 }
 
 
@@ -379,7 +400,6 @@ struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
 	struct tipc_node *n_ptr;
 	struct tipc_node_info node_info;
 	u32 payload_size;
-	u32 n_num;
 
 	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
 		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
@@ -390,15 +410,14 @@ struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
 						   " (network address)");
 
 	read_lock_bh(&tipc_net_lock);
-	if (!tipc_nodes) {
+	if (!tipc_num_nodes) {
 		read_unlock_bh(&tipc_net_lock);
 		return tipc_cfg_reply_none();
 	}
 
 	/* For now, get space for all other nodes */
 
-	payload_size = TLV_SPACE(sizeof(node_info)) *
-		(tipc_highest_node - 1);
+	payload_size = TLV_SPACE(sizeof(node_info)) * tipc_num_nodes;
 	if (payload_size > 32768u) {
 		read_unlock_bh(&tipc_net_lock);
 		return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
@@ -412,9 +431,8 @@ struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space)
 
 	/* Add TLVs for all nodes in scope */
 
-	for (n_num = 1; n_num <= tipc_highest_node; n_num++) {
-		n_ptr = tipc_nodes[n_num];
-		if (!n_ptr || !tipc_in_scope(domain, n_ptr->addr))
+	list_for_each_entry(n_ptr, &tipc_node_list, list) {
+		if (!tipc_in_scope(domain, n_ptr->addr))
 			continue;
 		node_info.addr = htonl(n_ptr->addr);
 		node_info.up = htonl(tipc_node_is_up(n_ptr));
@@ -433,7 +451,6 @@ struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
 	struct tipc_node *n_ptr;
 	struct tipc_link_info link_info;
 	u32 payload_size;
-	u32 n_num;
 
 	if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_NET_ADDR))
 		return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
@@ -472,11 +489,10 @@ struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
 
 	/* Add TLVs for any other links in scope */
 
-	for (n_num = 1; n_num <= tipc_highest_node; n_num++) {
+	list_for_each_entry(n_ptr, &tipc_node_list, list) {
 		u32 i;
 
-		n_ptr = tipc_nodes[n_num];
-		if (!n_ptr || !tipc_in_scope(domain, n_ptr->addr))
+		if (!tipc_in_scope(domain, n_ptr->addr))
 			continue;
 		tipc_node_lock(n_ptr);
 		for (i = 0; i < MAX_BEARERS; i++) {