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, 2 insertions, 2 deletions

diff --git a/net/tipc/socket.h b/net/tipc/socket.h
index 95b015909ac1..8be0da7df8fc 100644
--- a/net/tipc/socket.h
+++ b/net/tipc/socket.h
@@ -42,7 +42,6 @@
 #define TIPC_FLOWCTRL_WIN        (TIPC_CONNACK_INTV * 2)
 #define TIPC_CONN_OVERLOAD_LIMIT ((TIPC_FLOWCTRL_WIN * 2 + 1) * \
 				  SKB_TRUESIZE(TIPC_MAX_USER_MSG_SIZE))
-
 int tipc_socket_init(void);
 void tipc_socket_stop(void);
 int tipc_sock_create_local(struct net *net, int type, struct socket **res);
@@ -51,7 +50,8 @@ int tipc_sock_accept_local(struct socket *sock, struct socket **newsock,
 			   int flags);
 int tipc_sk_rcv(struct net *net, struct sk_buff_head *inputq);
 struct sk_buff *tipc_sk_socks_show(struct net *net);
-void tipc_sk_mcast_rcv(struct net *net, struct sk_buff *buf);
+void tipc_sk_mcast_rcv(struct net *net, struct sk_buff_head *arrvq,
+		       struct sk_buff_head *inputq);
 void tipc_sk_reinit(struct net *net);
 int tipc_sk_rht_init(struct net *net);
 void tipc_sk_rht_destroy(struct net *net);