tipc: send out RESET immediately when link goes down

When a link is taken down because of a node local event, such as
disabling of a bearer or an interface, we currently leave it to the
peer node to discover the broken communication. The default time for
such failure discovery is 1.5-2 seconds.

If we instead allow the terminating link endpoint to send out a RESET
message at the moment it is reset, we can achieve the impression that
both endpoints are going down instantly. Since this is a very common
scenario, we find it worthwhile to make this small modification.

Apart from letting the link produce the said message, we also have to
ensure that the interface is able to transmit it before TIPC is
detached. We do this by performing the disabling of a bearer in three
steps:

1) Disable reception of TIPC packets from the interface in question.
2) Take down the links, while allowing them so send out a RESET message.
3) Disable transmission of TIPC packets on the interface.

Apart from this, we now have to react on the NETDEV_GOING_DOWN event,
instead of as currently the NEDEV_DOWN event, to ensure that such
transmission is possible during the teardown phase.

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>

1 files changed, 12 insertions, 0 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 8c794c1dd531..737b5980020d 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -1062,6 +1062,18 @@ void tipc_link_build_ack_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, xmitq);
 }
 
+/* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
+ */
+void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
+{
+	int mtyp = RESET_MSG;
+
+	if (l->state == LINK_ESTABLISHING)
+		mtyp = ACTIVATE_MSG;
+
+	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, xmitq);
+}
+
 /* tipc_link_build_nack_msg: prepare link nack message for transmission
  */
 static void tipc_link_build_nack_msg(struct tipc_link *l,