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, 7 insertions, 4 deletions

diff --git a/net/tipc/node.c b/net/tipc/node.c
index c7fdf3dec92c..52308498f208 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -582,10 +582,10 @@ void tipc_node_unlock(struct tipc_node *node)
         namedq = node->namedq;
         publ_list = &node->publ_list;
 
-        node->action_flags &= ~(TIPC_MSG_EVT | TIPC_NOTIFY_NODE_DOWN |
-                                TIPC_NOTIFY_NODE_UP | TIPC_NOTIFY_LINK_UP |
-                                TIPC_NOTIFY_LINK_DOWN |
-                                TIPC_WAKEUP_BCAST_USERS |
+        node->action_flags &= ~(TIPC_MSG_EVT |
+                                TIPC_NOTIFY_NODE_DOWN | TIPC_NOTIFY_NODE_UP |
+                                TIPC_NOTIFY_LINK_DOWN | TIPC_NOTIFY_LINK_UP |
+                                TIPC_WAKEUP_BCAST_USERS | TIPC_BCAST_MSG_EVT |
                                 TIPC_NAMED_MSG_EVT);
 
         spin_unlock_bh(&node->lock);
@@ -612,6 +612,9 @@ void tipc_node_unlock(struct tipc_node *node)
 
         if (flags & TIPC_NAMED_MSG_EVT)
                 tipc_named_rcv(net, namedq);
+
+        if (flags & TIPC_BCAST_MSG_EVT)
+                tipc_bclink_input(net);
 }
 
 /* Caller should hold node lock for the passed node */