[ovs-dev] [PATCH] Setting miss_send_len on receiving NXT_SET_ASYNC_CONFIG message.

[Mehak Mahajan]

For the service controllers to receive any asynchronous messages, the
miss_send_len must be set to a non-zero value (refer to DESIGN).  On
receiving the NXT_SET_ASYNC_CONFIG message, the miss_send_len is set
to the default value unless it is set to a non-zero value earlier by
the OFPT_SET_CONFIG message.

Signed-off-by: Mehak Mahajan <mmahajan at nicira.com>
---
 DESIGN                        |   10 ++++++++--
 include/openflow/nicira-ext.h |    3 +++
 ofproto/ofproto.c             |    4 ++++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/DESIGN b/DESIGN
index f9345d1..a3a62b2 100644
--- a/DESIGN
+++ b/DESIGN
@@ -17,8 +17,14 @@ given controller receives OpenFlow asynchronous messages.  This
 section describes how all of these features interact.
 
 First, a service controller never receives any asynchronous messages
-unless it explicitly configures a miss_send_len greater than zero with
-an OFPT_SET_CONFIG message.
+unless it changes its miss_send_len from the service controller
+default of zero in one of the following ways:
+
+    - Sending an OFPT_SET_CONFIG message with nonzero miss_send_len.
+
+    - Sending any NXT_SET_ASYNC_CONFIG message: as a side effect, this
+      message changes the miss_send_len to
+      OFP_DEFAULT_MISS_SEND_LEN (128) for service controllers.
 
 Second, OFPT_FLOW_REMOVED and NXT_FLOW_REMOVED messages are generated
 only if the flow that was removed had the OFPFF_SEND_FLOW_REM flag
diff --git a/include/openflow/nicira-ext.h b/include/openflow/nicira-ext.h
index 2f46311..72cbb24 100644
--- a/include/openflow/nicira-ext.h
+++ b/include/openflow/nicira-ext.h
@@ -305,6 +305,9 @@ enum nx_role {
  * with value 1<<2 == 4 in port_status_mask[1] determines whether the
  * controller will receive OFPT_PORT_STATUS messages with reason OFPPR_MODIFY
  * (value 2) when the controller has a "slave" role.
+ *
+ * As a side effect, for service controllers, this message changes the
+ * miss_send_len from default of zero to OFP_DEFAULT_MISS_SEND_LEN (128).
  */
 struct nx_async_config {
     struct nicira_header nxh;
diff --git a/ofproto/ofproto.c b/ofproto/ofproto.c
index 38430ab..c413402 100644
--- a/ofproto/ofproto.c
+++ b/ofproto/ofproto.c
@@ -3315,6 +3315,10 @@ handle_nxt_set_async_config(struct ofconn *ofconn, const struct ofp_header *oh)
     slave[OAM_FLOW_REMOVED] = ntohl(msg->flow_removed_mask[1]);
 
     ofconn_set_async_config(ofconn, master, slave);
+    if ((ofconn_get_type(ofconn) == OFCONN_SERVICE) &&
+        !ofconn_get_miss_send_len(ofconn)) {
+        ofconn_set_miss_send_len(ofconn, OFP_DEFAULT_MISS_SEND_LEN);
+    }
 
     return 0;
 }
-- 
1.7.2.5