tipc: Add monitoring of number of nodes discovered by bearer

Augments TIPC's discovery object to track the number of neighboring nodes
having an active link to the associated bearer.

This means tipc_disc_update_link_req() becomes either one of:

       tipc_disc_add_dest()
or:
       tipc_disc_remove_dest()

depending on the code flow direction of things.
Signed-off-by: Allan Stephens <Allan.Stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

net/tipc/bearer.c

@@ -344,15 +344,15 @@ struct sk_buff *tipc_bearer_get_names(void)
 void tipc_bearer_add_dest(struct tipc_bearer *b_ptr, u32 dest)
 {
 	tipc_nmap_add(&b_ptr->nodes, dest);
-	tipc_disc_update_link_req(b_ptr->link_req);
 	tipc_bcbearer_sort();
+	tipc_disc_add_dest(b_ptr->link_req);
 }
 
 void tipc_bearer_remove_dest(struct tipc_bearer *b_ptr, u32 dest)
 {
 	tipc_nmap_remove(&b_ptr->nodes, dest);
-	tipc_disc_update_link_req(b_ptr->link_req);
 	tipc_bcbearer_sort();
+	tipc_disc_remove_dest(b_ptr->link_req);
 }
 
 /*

net/tipc/discover.c

@@ -53,6 +53,7 @@
  * @bearer: bearer issuing requests
  * @dest: destination address for request messages
  * @domain: network domain to which links can be established
+ * @num_nodes: number of nodes currently discovered (i.e. with an active link)
  * @buf: request message to be (repeatedly) sent
  * @timer: timer governing period between requests
  * @timer_intv: current interval between requests (in ms)
@@ -61,6 +62,7 @@ struct link_req {
 	struct tipc_bearer *bearer;
 	struct tipc_media_addr dest;
 	u32 domain;
+	int num_nodes;
 	struct sk_buff *buf;
 	struct timer_list timer;
 	unsigned int timer_intv;
@@ -216,15 +218,12 @@ void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr)
 }
 
 /**
- * tipc_disc_update_link_req - update frequency of periodic link setup requests
+ * disc_update - update frequency of periodic link setup requests
  * @req: ptr to link request structure
  */
 
-void tipc_disc_update_link_req(struct link_req *req)
+static void disc_update(struct link_req *req)
 {
-	if (!req)
-		return;
-
 	if (req->timer_intv == TIPC_LINK_REQ_SLOW) {
 		if (!req->bearer->nodes.count) {
 			req->timer_intv = TIPC_LINK_REQ_FAST;
@@ -240,6 +239,28 @@ void tipc_disc_update_link_req(struct link_req *req)
 	}
 }
 
+/**
+ * tipc_disc_add_dest - increment set of discovered nodes
+ * @req: ptr to link request structure
+ */
+
+void tipc_disc_add_dest(struct link_req *req)
+{
+	req->num_nodes++;
+	disc_update(req);
+}
+
+/**
+ * tipc_disc_remove_dest - decrement set of discovered nodes
+ * @req: ptr to link request structure
+ */
+
+void tipc_disc_remove_dest(struct link_req *req)
+{
+	req->num_nodes--;
+	disc_update(req);
+}
+
 /**
  * disc_send_msg - send link setup request message
  * @req: ptr to link request structure
@@ -307,6 +328,7 @@ int tipc_disc_create(struct tipc_bearer *b_ptr,
 	memcpy(&req->dest, dest, sizeof(*dest));
 	req->bearer = b_ptr;
 	req->domain = dest_domain;
+	req->num_nodes = 0;
 	req->timer_intv = TIPC_LINK_REQ_INIT;
 	k_init_timer(&req->timer, (Handler)disc_timeout, (unsigned long)req);
 	k_start_timer(&req->timer, req->timer_intv);

net/tipc/discover.h

@@ -42,7 +42,8 @@ struct link_req;
 int tipc_disc_create(struct tipc_bearer *b_ptr, struct tipc_media_addr *dest,
 		     u32 dest_domain);
 void tipc_disc_delete(struct link_req *req);
-void tipc_disc_update_link_req(struct link_req *req);
+void tipc_disc_add_dest(struct link_req *req);
+void tipc_disc_remove_dest(struct link_req *req);
 void tipc_disc_recv_msg(struct sk_buff *buf, struct tipc_bearer *b_ptr);
 
 #endif