tipc: eliminate race condition at multicast reception

In a previous commit in this series we resolved a race problem during
unicast message reception.

Here, we resolve the same problem at multicast reception. We apply the
same technique: an input queue serializing the delivery of arriving
buffers. The main difference is that here we do it in two steps.
First, the broadcast link feeds arriving buffers into the tail of an
arrival queue, which head is consumed at the socket level, and where
destination lookup is performed. Second, if the lookup is successful,
the resulting buffer clones are fed into a second queue, the input
queue. This queue is consumed at reception in the socket just like
in the unicast case. Both queues are protected by the same lock, -the
one of the input queue.

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, 5 insertions, 2 deletions

diff --git a/net/tipc/node.h b/net/tipc/node.h
index c2b0fcf4042b..20ec13f9bede 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -1,7 +1,7 @@
 /*
  * net/tipc/node.h: Include file for TIPC node management routines
  *
- * Copyright (c) 2000-2006, 2014, Ericsson AB
+ * Copyright (c) 2000-2006, 2014-2015, Ericsson AB
  * Copyright (c) 2005, 2010-2014, Wind River Systems
  * All rights reserved.
  *
@@ -63,7 +63,8 @@ enum {
 	TIPC_WAKEUP_BCAST_USERS		= (1 << 5),
 	TIPC_NOTIFY_LINK_UP		= (1 << 6),
 	TIPC_NOTIFY_LINK_DOWN		= (1 << 7),
-	TIPC_NAMED_MSG_EVT		= (1 << 8)
+	TIPC_NAMED_MSG_EVT		= (1 << 8),
+	TIPC_BCAST_MSG_EVT		= (1 << 9)
 };
 
 /**
@@ -74,6 +75,7 @@ enum {
  * @oos_state: state tracker for handling OOS b'cast messages
  * @deferred_queue: deferred queue saved OOS b'cast message received from node
  * @reasm_buf: broadcast reassembly queue head from node
+ * @inputq_map: bitmap indicating which inqueues should be kicked
  * @recv_permitted: true if node is allowed to receive b'cast messages
  */
 struct tipc_node_bclink {
@@ -84,6 +86,7 @@ struct tipc_node_bclink {
 	u32 deferred_size;
 	struct sk_buff_head deferred_queue;
 	struct sk_buff *reasm_buf;
+	int inputq_map;
 	bool recv_permitted;
 };