tipc: use message to abort connections when losing contact to node

In the current implementation, each 'struct tipc_node' instance keeps
a linked list of those ports/sockets that are connected to the node
represented by that struct. The purpose of this is to let the node
object know which sockets to alert when it loses contact with its peer
node, i.e., which sockets need to have their connections aborted.

This entails an unwanted direct reference from the node structure
back to the port/socket structure, and a need to grab port_lock
when we have to make an upcall to the port. We want to get rid of
this unecessary BH entry point into the socket, and also eliminate
its use of port_lock.

In this commit, we instead let the node struct keep list of "connected
socket" structs, which each represents a connected socket, but is
allocated independently by the node at the moment of connection. If
the node loses contact with its peer node, the list is traversed, and
a "connection abort" message is created for each entry in the list. The
message is sent to it respective connected socket using the ordinary
data path, and the receiving socket aborts its connections upon reception
of the message.

This enables us to get rid of the direct reference from 'struct node' to
´struct port', and another unwanted BH access point to the latter.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/net/tipc/node.h b/net/tipc/node.h
index 2ebf9e8b50fd..522d6f3157b3 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -117,6 +117,7 @@ struct tipc_node {
         u32 signature;
         struct list_head nsub;
         struct sk_buff_head waiting_sks;
+        struct list_head conn_sks;
         struct rcu_head rcu;
 };
 
@@ -135,6 +136,8 @@ struct sk_buff *tipc_node_get_links(const void *req_tlv_area, int req_tlv_space)
 struct sk_buff *tipc_node_get_nodes(const void *req_tlv_area, int req_tlv_space);
 int tipc_node_get_linkname(u32 bearer_id, u32 node, char *linkname, size_t len);
 void tipc_node_unlock(struct tipc_node *node);
+int tipc_node_add_conn(u32 dnode, u32 port, u32 peer_port);
+void tipc_node_remove_conn(u32 dnode, u32 port);
 
 static inline void tipc_node_lock(struct tipc_node *node)
 {