tipc: simplify socket multicast reception

The structure 'tipc_port_list' is used to collect port numbers
representing multicast destination socket on a receiving node.
The list is not based on a standard linked list, and is in reality
optimized for the uncommon case that there are more than one
multicast destinations per node. This makes the list handling
unecessarily complex, and as a consequence, even the socket
multicast reception becomes more complex.

In this commit, we replace 'tipc_port_list' with a new 'struct
tipc_plist', which is based on a standard list. We give the new
list stack (push/pop) semantics, someting that simplifies
the implementation of the function tipc_sk_mcast_rcv().

Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 41 insertions, 3 deletions

diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c
index ce09b86..18a3d44 100644
--- a/net/tipc/name_table.c
+++ b/net/tipc/name_table.c
@@ -1,7 +1,7 @@
 /*
  * net/tipc/name_table.c: TIPC name table code
  *
- * Copyright (c) 2000-2006, 2014, Ericsson AB
+ * Copyright (c) 2000-2006, 2014-2015, Ericsson AB
  * Copyright (c) 2004-2008, 2010-2014, Wind River Systems
  * All rights reserved.
  *
@@ -618,7 +618,7 @@ not_found:
  * Returns non-zero if any off-node ports overlap
  */
 int tipc_nametbl_mc_translate(struct net *net, u32 type, u32 lower, u32 upper,
-			      u32 limit, struct tipc_port_list *dports)
+			      u32 limit, struct tipc_plist *dports)
 {
 	struct name_seq *seq;
 	struct sub_seq *sseq;
@@ -643,7 +643,7 @@ int tipc_nametbl_mc_translate(struct net *net, u32 type, u32 lower, u32 upper,
 		info = sseq->info;
 		list_for_each_entry(publ, &info->node_list, node_list) {
 			if (publ->scope <= limit)
-				tipc_port_list_add(dports, publ->ref);
+				tipc_plist_push(dports, publ->ref);
 		}
 
 		if (info->cluster_list_size != info->node_list_size)
@@ -1212,3 +1212,41 @@ int tipc_nl_name_table_dump(struct sk_buff *skb, struct netlink_callback *cb)
 
 	return skb->len;
 }
+
+void tipc_plist_push(struct tipc_plist *pl, u32 port)
+{
+	struct tipc_plist *nl;
+
+	if (likely(!pl->port)) {
+		pl->port = port;
+		return;
+	}
+	if (pl->port == port)
+		return;
+	list_for_each_entry(nl, &pl->list, list) {
+		if (nl->port == port)
+			return;
+	}
+	nl = kmalloc(sizeof(*nl), GFP_ATOMIC);
+	if (nl) {
+		nl->port = port;
+		list_add(&nl->list, &pl->list);
+	}
+}
+
+u32 tipc_plist_pop(struct tipc_plist *pl)
+{
+	struct tipc_plist *nl;
+	u32 port = 0;
+
+	if (likely(list_empty(&pl->list))) {
+		port = pl->port;
+		pl->port = 0;
+		return port;
+	}
+	nl = list_first_entry(&pl->list, typeof(*nl), list);
+	port = nl->port;
+	list_del(&nl->list);
+	kfree(nl);
+	return port;
+}