tipc: guarantee delivery of UP event before first broadcast
The following scenario is possible:
- A user joins a group, and immediately sends out a broadcast message
to its members.
- The broadcast message, following a different data path than the
initial JOIN message sent out during the joining procedure, arrives
to a receiver before the latter..
- The receiver drops the message, since it is not ready to accept any
messages until the JOIN has arrived.
We avoid this by treating group protocol JOIN messages like unicast
messages.
- We let them pass through the recipient's multicast input queue, just
like ordinary unicasts.
- We force the first following broadacst to be sent as replicated
unicast and being acknowledged by the recipient before accepting
any more broadcast transmissions.
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index b1f1c3c..2bbab4f 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -2762,6 +2762,10 @@ static int tipc_sk_join(struct tipc_sock *tsk, struct tipc_group_req *mreq)
rc = tipc_sk_publish(tsk, mreq->scope, &seq);
if (rc)
tipc_group_delete(net, grp);
+
+ /* Eliminate any risk that a broadcast overtakes the sent JOIN */
+ tsk->mc_method.rcast = true;
+ tsk->mc_method.mandatory = true;
return rc;
}
