tipc: send out join messages as soon as new member is discovered

When a socket is joining a group, we look up in the binding table to
find if there are already other members of the group present. This is
used for being able to return EAGAIN instead of EHOSTUNREACH if the
user proceeds directly to a send attempt.

However, the information in the binding table can be used to directly
set the created member in state MBR_PUBLISHED and send a JOIN message
to the peer, instead of waiting for a topology PUBLISH event to do this.
When there are many members in a group, the propagation time for such
events can be significant, and we can save time during the join
operation if we use the initial lookup result fully.

In this commit, we eliminate the member state MBR_DISCOVERED which has
been the result of the initial lookup, and do instead go directly to
MBR_PUBLISHED, which initiates the setup.

After this change, the tipc_member FSM looks as follows:

     +-----------+
---->| PUBLISHED |-----------------------------------------------+
PUB- +-----------+                                 LEAVE/WITHRAW |
LISH       |JOIN                                                 |
           |     +-------------------------------------------+   |
           |     |                            LEAVE/WITHDRAW |   |
           |     |                +------------+             |   |
           |     |   +----------->|  PENDING   |---------+   |   |
           |     |   |msg/maxactv +-+---+------+  LEAVE/ |   |   |
           |     |   |              |   |       WITHDRAW |   |   |
           |     |   |   +----------+   |                |   |   |
           |     |   |   |revert/maxactv|                |   |   |
           |     |   |   V              V                V   V   V
           |   +----------+  msg  +------------+       +-----------+
           +-->|  JOINED  |------>|   ACTIVE   |------>|  LEAVING  |--->
           |   +----------+       +--- -+------+ LEAVE/+-----------+DOWN
           |        A   A               |      WITHDRAW A   A    A   EVT
           |        |   |               |RECLAIM        |   |    |
           |        |   |REMIT          V               |   |    |
           |        |   |== adv   +------------+        |   |    |
           |        |   +---------| RECLAIMING |--------+   |    |
           |        |             +-----+------+  LEAVE/    |    |
           |        |                   |REMIT   WITHDRAW   |    |
           |        |                   |< adv              |    |
           |        |msg/               V            LEAVE/ |    |
           |        |adv==ADV_IDLE+------------+   WITHDRAW |    |
           |        +-------------|  REMITTED  |------------+    |
           |                      +------------+                 |
           |PUBLISH                                              |
JOIN +-----------+                                LEAVE/WITHDRAW |
---->|  JOINING  |-----------------------------------------------+
     +-----------+

Acked-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, 3 insertions, 1 deletions

diff --git a/net/tipc/group.h b/net/tipc/group.h
index 5ffffd0121a2..dee79477d499 100644
--- a/net/tipc/group.h
+++ b/net/tipc/group.h
@@ -44,8 +44,10 @@ struct tipc_msg;
 
 struct tipc_group *tipc_group_create(struct net *net, u32 portid,
 				     struct tipc_group_req *mreq);
+void tipc_group_join(struct net *net, struct tipc_group *grp, int *sk_rcv_buf);
 void tipc_group_delete(struct net *net, struct tipc_group *grp);
-void tipc_group_add_member(struct tipc_group *grp, u32 node, u32 port);
+void tipc_group_add_member(struct tipc_group *grp, u32 node,
+			   u32 port, u32 instance);
 struct tipc_nlist *tipc_group_dests(struct tipc_group *grp);
 void tipc_group_self(struct tipc_group *grp, struct tipc_name_seq *seq,
 		     int *scope);